阅读说明：本技术 一种对位芳纶与聚醚酰亚胺共混浆料及其制备方法、对位芳纶涂层隔膜 (Para-aramid and polyetherimide blend slurry, preparation method thereof and para-aramid coating diaphragm ) 是由 袁海朝 徐锋 李腾 苏碧海 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种对位芳纶与聚醚酰亚胺共混浆料及其制备方法、对位芳纶涂层隔膜。其制备方法中,通过合成对位芳纶时提高添加氯化钙的量让游离的钙离子跟氯离子占据对位芳纶中的氢和氧的位置来消除对位芳纶纳米纤维之间的氢键,然后利用聚丁二醇来阻断对位芳纶分子之间的连接,控制大分子之间的聚合,使对位芳纶浆料形成高分散不易变质的浆料,然后添加经过溶解后的聚醚酰亚胺溶液,让高分散型的对位芳纶纳米纤维均匀的吸附在聚醚酰亚胺分子链当中,当浆料萃取固化时,聚醚酰亚胺分子会因造孔剂的脱离,形成多孔网撑起对位芳纶纳米纤维的骨架,使整体隔膜产生耐高温,高孔隙率的涂层隔膜。(The invention discloses para-aramid and polyetherimide blend slurry, a preparation method thereof and a para-aramid coating diaphragm. In the preparation method, the amount of added calcium chloride is increased when para-aramid is synthesized, free calcium ions and chloride ions occupy positions of hydrogen and oxygen in para-aramid to eliminate hydrogen bonds between para-aramid nano fibers, then polybutylene glycol is used for blocking connection between para-aramid molecules, polymerization between macromolecules is controlled, the para-aramid slurry is made into highly-dispersed slurry which is not easy to deteriorate, then dissolved polyetherimide solution is added, the highly-dispersed para-aramid nano fibers are uniformly adsorbed in a polyetherimide molecular chain, when the slurry is extracted and solidified, the polyetherimide molecules can be separated due to pore-forming agents to form a porous net to support a skeleton of the para-aramid nano fibers, and the whole membrane is made into a coating membrane with high temperature resistance and high porosity.)

1. A preparation method of para-aramid and polyetherimide blend slurry is characterized by comprising the following steps: the method comprises the following steps:

step 1: adding calcium chloride into N-methylpyrrolidone, heating and stirring until the calcium chloride is completely dissolved to obtain a first mixed solution;

step 2: cooling the first mixed solution obtained in the step (1) to room temperature, adding polytetramethylene glycol into the first mixed solution, uniformly stirring, adding gas-phase nano ceramic particles, uniformly stirring, and sanding to obtain a second mixed solution;

and step 3: under the protection of inert gas, cooling the second mixed solution obtained in the step (2) to 10-15 ℃, then adding p-phenylenediamine into the second mixed solution, and stirring to completely dissolve the p-phenylenediamine to obtain a third mixed solution; cooling the third mixed solution to-2-0 deg.C, adding terephthaloyl chloride, stirring at-2-0 deg.C for 10-15min, and recovering to room temperature and stirring for 15-20min to obtain a fourth mixed solution;

and 4, step 4: adding a dimethyl carbonate pore-forming agent into the fourth mixed solution obtained in the step (3), and uniformly stirring to obtain a fifth mixed solution;

and 5: adding the polyetherimide particles into N-methyl pyrrolidone, heating and stirring until the polyetherimide particles are completely dissolved to obtain a sixth mixed solution;

step 6: and (4) mixing the fifth mixed solution obtained in the step (4) with the sixth mixed solution obtained in the step (5), and uniformly stirring to obtain the para-aramid and polyetherimide blended slurry.

2. The method of claim 1, wherein: in the step 1, the ratio of the calcium chloride to the N-methyl pyrrolidone is (8-15) in parts by mass: (85-92).

3. The method of claim 1, wherein: in the step 2, the ratio of the first mixed solution to the polytetramethylene glycol to the gas-phase nano ceramic particles is (87-92): (3-5): (3-10).

4. The method of claim 1, wherein: in the step 3, the molar ratio of the p-phenylenediamine to the terephthaloyl chloride is 1: 1;

the mass part of the second mixed solution and the total mass part of the p-phenylenediamine and the terephthaloyl chloride are (93-95): (5-7).

5. The method of claim 1, wherein: in the step 4, the ratio of the fourth mixed solution to the dimethyl carbonate is (93-95) in parts by mass: (5-7).

6. The method of claim 1, wherein: in the step 5, the ratio of the polyetherimide particles to the N-methylpyrrolidone is (10-20) in parts by mass: (80-90).

7. The method of claim 1, wherein: in the step 6, the ratio of the fifth mixed solution to the sixth mixed solution is (70-80) in parts by mass: (20-30).

8. A para-aramid and polyetherimide blend slurry prepared using the preparation method of any one of claims 1 to 7.

9. A para-aramid coated separator comprising a base film and a coating layer formed of the para-aramid and polyetherimide blend slurry of claim 8 coated on one or both sides of the base film.

10. The para-aramid coated membrane according to claim 9, wherein the coating is roll-coated with an anilox roll, and the slurry coated on the base film is subjected to extraction curing by using an extraction curing liquid.

Technical Field

The invention relates to the technical field of lithium battery diaphragms, in particular to para-aramid and polyetherimide blend slurry, a preparation method thereof and a para-aramid coating diaphragm.

Background

Although the para-aramid coating has high temperature resistance, the molecular weight of the para-aramid coating has great influence on the coating of the diaphragm, the proper molecular weight is difficult to grasp in the synthesis process, the temperature resistance and the binding power are reduced when the molecular weight is too small, and the molecular weight is easy to solidify and deteriorate when the molecular weight is too large, so that a method for controlling the molecular weight is needed in the synthesis process.

The adsorption capacity between the para-aramid fibers is very strong, the para-aramid fibers are coated on the surface of the diaphragm and are easily bonded together, so that the porosity of the diaphragm is very small, and a special framework structure is needed to separate and support the nanofibers, so that the nanofibers have enough pore diameters on the diaphragm.

Disclosure of Invention

The invention aims to provide a preparation method of para-aramid and polyetherimide blend slurry aiming at the technical defect that the porosity of a membrane is reduced due to a para-aramid coating in the prior art.

The invention also aims to provide the para-aramid and polyetherimide blending slurry prepared by the preparation method.

The invention also aims to provide the para-aramid coated membrane.

The technical scheme adopted for realizing the purpose of the invention is as follows:

a preparation method of para-aramid and polyetherimide blend slurry comprises the following steps:

step 1: adding calcium chloride into N-methylpyrrolidone (NMP), heating and stirring until the calcium chloride is completely dissolved to obtain a first mixed solution;

wherein the mass ratio of the calcium chloride to the NMP is (8-15): (85-92);

heating at 60-80 deg.C, and stirring for 40-80 min;

step 2: cooling the first mixed solution obtained in the step (1) to room temperature, adding polytetramethylene glycol into the first mixed solution, uniformly stirring, adding gas-phase nano ceramic particles, uniformly stirring, and sanding to obtain a second mixed solution;

wherein the mass ratio of the first mixed solution to the polytetramethylene glycol to the gas-phase nano ceramic particles is (87-92): (3-5): (3-10);

the sanding time is 15-20min, and the sanding rotating speed is 800-;

and step 3: under the protection of inert gas, cooling the second mixed solution obtained in the step (2) to 10-15 ℃, then adding p-phenylenediamine into the second mixed solution, and stirring to completely dissolve the p-phenylenediamine to obtain a third mixed solution; cooling the third mixed solution to-2-0 deg.C, adding terephthaloyl chloride, stirring at-2-0 deg.C for 10-15min, and recovering to room temperature and stirring for 15-20min to obtain a fourth mixed solution;

wherein the molar ratio of p-phenylenediamine to terephthaloyl chloride is 1: 1;

the mass of the second mixed solution and the ratio of the total mass of the p-phenylenediamine to the terephthaloyl chloride are (93-95): (5-7);

and 4, step 4: adding a dimethyl carbonate pore-forming agent into the fourth mixed solution obtained in the step (3), and uniformly stirring to obtain a fifth mixed solution;

wherein the mass ratio of the fourth mixed solution to the dimethyl carbonate is (93-95): (5-7);

the stirring revolution speed is 35-40r/min, and the rotation speed is 1000-;

and 5: adding the polyetherimide particles into NMP, and stirring at 60-80 ℃ until the polyetherimide particles are completely dissolved to obtain a sixth mixed solution;

wherein the mass ratio of the polyetherimide particles to the NMP is (10-20): (80-90);

step 6: mixing the fifth mixed solution obtained in the step 4 and the sixth mixed solution obtained in the step 5, and uniformly stirring to obtain para-aramid and polyetherimide blended slurry;

wherein the mass ratio of the fifth mixed solution to the sixth mixed solution is (70-80): (20-30).

In another aspect of the invention, the para-aramid and polyetherimide blending slurry prepared by the preparation method is used.

In another aspect of the present invention, a para-aramid coated membrane includes a base film and a coating layer formed of a blend slurry of para-aramid and polyetherimide coated on one or both sides of the base film. The coating mode is anilox roller coating, and the slurry coated on the base film is subjected to extraction curing by using an extraction curing solution.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the para-aramid and polyetherimide blending slurry provided by the invention, the amount of calcium chloride is large, free calcium ions and chloride ions occupy positions of hydrogen and oxygen in para-aramid to eliminate hydrogen bonds between para-aramid nano fibers, and then polybutylene glycol is used for blocking connection between para-aramid molecules and controlling polymerization between macromolecules, so that the para-aramid slurry forms a slurry which is highly dispersed and is not easy to deteriorate, thereby avoiding reduction of porosity of a membrane and further avoiding increase of a ventilation value.

2. According to the para-aramid and polyetherimide blending slurry provided by the invention, the dissolved polyetherimide is added, so that the high-dispersion para-aramid nano-fiber is uniformly adsorbed in a polyetherimide molecular chain, and when the slurry is extracted and cured, the polyetherimide molecules can be separated due to the pore-forming agent to form a porous net to support the skeleton of the para-aramid nano-fiber, so that the whole membrane can generate a high-temperature-resistant and high-porosity coating membrane.

3. The para-aramid coating diaphragm provided by the invention has good air permeability and heat resistance.

Drawings

FIG. 1 is an electron microscope image of a para-aramid coated membrane formed by coating a para-aramid and polyetherimide blend slurry prepared in example 1;

fig. 2 is an electron microscope image of a para-aramid coated membrane formed by coating the para-aramid and polyetherimide blend slurry prepared in the comparative example 1.

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 para-aramid and polyetherimide blend slurry comprises the following steps:

step 1: adding 8 parts by mass of calcium chloride into 92 parts by mass of N-methylpyrrolidone (NMP), heating to 60 ℃ by using a stirring jacket, and stirring for 60min until the calcium chloride is completely dissolved to obtain a first mixed solution;

step 2: cooling the first mixed solution obtained in the step 1 to room temperature, adding polytetramethylene glycol into the first mixed solution, uniformly stirring by a paddle type stirrer for 5min, closing rotation, wherein the revolution speed of the paddle type stirrer is 35r/min (the stirrer in the stirrer is in a paddle type, generally large, slow and called revolution, a paddle type stirring blade is provided with a small dispersion disc, and can rotate along with the stirrer in the revolution process, and the rotation speed is high and called rotation), adding gas phase nano ceramic particles, uniformly stirring, wherein the revolution speed is 40r/min, the rotation speed is 2000r/min, the stirring time is 30min, and finally adding a rod pin type nano sand mill for sanding, wherein the sanding rotation speed is 900r/min, and the sanding time is 15 min; the ratio of the first mixed solution to the polytetramethylene glycol to the gas-phase nano ceramic particles is 87:3:10 in parts by mass.

And step 3: introducing nitrogen into the reaction kettle for protection, cooling the second mixed solution obtained in the step (2) to 10 ℃, then adding p-phenylenediamine into the second mixed solution, and stirring for 15min to completely dissolve the p-phenylenediamine to obtain a third mixed solution; cooling the third mixed solution to-2 ℃, adding terephthaloyl chloride, stirring at-2 ℃ for 10min, then returning to room temperature and continuing stirring for 15min to obtain a fourth mixed solution; the molar ratio of the p-phenylenediamine to the terephthaloyl chloride is 1: 1; the ratio of the mass of the second mixed solution to the total mass of the p-phenylenediamine and the terephthaloyl chloride is 93: 7.

and 4, step 4: adding a dimethyl carbonate pore-forming agent into the fourth mixed solution obtained in the step (3), and uniformly stirring the mixture by using a paddle stirrer to obtain a fifth mixed solution; the stirring time is 30min, the revolution speed of the paddle type stirrer is 35r/min, the rotation speed is 1000r/min, and the mass ratio of the fourth mixed solution to the dimethyl carbonate is 95: 5.

And 5: adding polyetherimide particles into N-methyl pyrrolidone, heating and stirring at 60 ℃ until the polyetherimide particles are completely dissolved to obtain a sixth mixed solution; the mass ratio of the polyetherimide particles to the N-methylpyrrolidone is 10: 90;

step 6: mixing the fifth mixed solution obtained in the step 4 and the sixth mixed solution obtained in the step 5, and uniformly stirring to obtain para-aramid and polyetherimide blended slurry, wherein the stirring time is 30 min; the mass ratio of the fifth mixed solution to the sixth mixed solution was 70: 30.

A para-aramid coated membrane comprises a PE base membrane with the thickness of 12 mu m and a coating formed by the para-aramid and polyetherimide blended slurry coated on two sides of the base membrane. Wherein the coating mode is anilox roller coating

Comparative example 1

Comparative example 1 the fifth mixed solution obtained in step 4, which does not include step 5 and step 6 as compared to example 1, was used as a para-aramid pulp.

Example 2

A preparation method of para-aramid and polyetherimide blend slurry comprises the following steps:

step 1: adding 11 parts by mass of calcium chloride into 89 parts by mass of N-methylpyrrolidone (NMP), heating to 70 ℃ by using a stirring jacket, and stirring for 60min until the calcium chloride is completely dissolved to obtain a first mixed solution;

step 2: cooling the first mixed solution obtained in the step 1 to room temperature, adding polytetramethylene glycol into the first mixed solution, uniformly stirring the mixture by a paddle type stirrer for 7min, closing rotation, keeping the revolution speed at 35r/min, adding gas-phase nano ceramic particles, uniformly stirring the mixture, keeping the revolution speed at 40r/min, keeping the rotation speed at 2000r/min, keeping the stirring time at 35min, and finally adding the mixture into a rod pin type nano sand mill for sanding, wherein the sanding speed is set to 900r/min, and the sanding time is 17 min; the ratio of the first mixed solution to the polytetramethylene glycol to the gas-phase nano ceramic particles is 90:4:6 in parts by mass.

And step 3: introducing nitrogen into the reaction kettle for protection, cooling the second mixed solution obtained in the step (2) to 12 ℃, then adding p-phenylenediamine into the second mixed solution, and stirring for 17min to completely dissolve the p-phenylenediamine to obtain a third mixed solution; cooling the third mixed solution to-1 ℃, adding terephthaloyl chloride, stirring at-2 ℃ for 13min, then returning to room temperature and continuing stirring for 17min to obtain a fourth mixed solution; the molar ratio of the p-phenylenediamine to the terephthaloyl chloride is 1: 1; the ratio of the mass parts of the second mixed solution to the total mass parts of the p-phenylenediamine and the terephthaloyl dichloride is 94: 6.

And 4, step 4: adding a dimethyl carbonate pore-forming agent into the fourth mixed solution obtained in the step (3), and uniformly stirring to obtain a fifth mixed solution; the stirring time is 30min, the revolution speed is 37r/min, the rotation speed is 1300r/min, and the ratio of the fourth mixed solution to the dimethyl carbonate is 94:6 according to the parts by weight.

And 5: adding polyetherimide particles into N-methyl pyrrolidone, heating and stirring at 80 ℃ until the polyetherimide particles are completely dissolved to obtain a sixth mixed solution; the mass ratio of the polyetherimide to the N-methylpyrrolidone is 15: 85;

step 6: mixing the fifth mixed solution obtained in the step 4 and the sixth mixed solution obtained in the step 5, and uniformly stirring to obtain para-aramid and polyetherimide blended slurry, wherein the stirring time is 30 min; the ratio of the fifth mixed solution to the sixth mixed solution is 75:25 in parts by mass.

Example 3

A preparation method of para-aramid and polyetherimide blend slurry comprises the following steps:

step 1: adding 15 parts by mass of calcium chloride into 85 parts by mass of N-methylpyrrolidone (NMP), heating to 80 ℃ by using a stirring jacket, and stirring until the calcium chloride is completely dissolved to obtain a first mixed solution;

step 2: cooling the first mixed solution obtained in the step 1 to room temperature, then adding polytetramethylene glycol into the first mixed solution and uniformly stirring, wherein the stirring time is 10min, the rotation is closed, the revolution speed is 35r/min, then adding gas-phase nano ceramic particles and uniformly stirring, the stirring revolution speed is 40r/min, the rotation speed is 2000r/min, the stirring time is 40min, and finally adding the mixture into a pin type nano sand mill for sanding, wherein the sanding speed is set to 900r/min, and the sanding time is 20 min; the ratio of the first mixed solution to the polytetramethylene glycol to the gas-phase nano ceramic particles is 92:5:3 in parts by mass.

And step 3: introducing nitrogen into the reaction kettle for protection, cooling the second mixed solution obtained in the step (2) to 15 ℃, then adding p-phenylenediamine into the second mixed solution, and stirring for 20min to completely dissolve the p-phenylenediamine to obtain a third mixed solution; cooling the third mixed solution to 0 ℃, adding terephthaloyl chloride, stirring at-2 ℃ for 15min, then returning to room temperature and continuing stirring for 20min to obtain a fourth mixed solution; the molar ratio of the p-phenylenediamine to the terephthaloyl chloride is 1: 1; the ratio of the mass portion of the second mixed solution to the total mass portion of the p-phenylenediamine and the terephthaloyl chloride is 95: 5.

And 4, step 4: adding a dimethyl carbonate pore-forming agent into the fourth mixed solution obtained in the step (3), and uniformly stirring to obtain a fifth mixed solution; the stirring time is 30min, the stirring revolution speed is 40r/min, the rotation speed is 1500r/min, and the ratio of the fourth mixed solution to the dimethyl carbonate is 93:7 according to the parts by weight.

And 5: adding polyetherimide particles into N-methyl pyrrolidone, heating and stirring at 80 ℃ until the polyetherimide particles are completely dissolved to obtain a sixth mixed solution; the mass ratio of the polyetherimide to the N-methylpyrrolidone is 20: 80;

step 6: mixing the fifth mixed solution obtained in the step 4 and the sixth mixed solution obtained in the step 5, and uniformly stirring to obtain para-aramid and polyetherimide blended slurry, wherein the stirring time is 30 min; the ratio of the fifth mixed solution to the sixth mixed solution is 80:20 in parts by mass.

Comparative example 2

Comparative example 2 is different from example 3 in that the mass ratio of calcium chloride and N-methylpyrrolidone in step 1 is 3: 97. The other steps are identical to example 3.

Example 4

A p-aramid coated membrane comprising a PE base film having a thickness of 12 μm and the above-mentioned p-aramid and polyetherimide blend slurry of examples 1 to 3 coated on both sides of the base film and the p-aramid slurry prepared in comparative examples 1 to 2. The coating mode is anilox roller coating, and the slurry coated on the base film is subjected to extraction curing by using an extraction curing liquid.

The extraction tank is divided into 10 small tanks, a diaphragm penetrates through each tank up and down, the tank depth is about one meter, the first three tanks adopt extraction liquid with different proportions, the extraction solidification liquid is mixed solution of deionized water and NMP, the mass ratio of the NMP to the water in the first tank is 5:1, the mass ratio of the NMP to the water in the second tank is 1:1, the mass ratio of the NMP to the water in the third tank is 2:3, the process is extracted by three coagulation baths with different concentrations, and the other tanks are washed by the deionized water.

Polyetherimide and para-aramid are all dissolved in solvent NMP, when the slurry passes through water, because the solvent can be more easily dissolved in water, the solvent in the slurry is taken away by the water, because the solvent is lacked in the slurry, the polymer in the slurry can be solidified and bonded on the diaphragm, and the aperture is too small for preventing the slurry from being solidified too fast, so that the solvent is added in the water before extraction to slow down the solidification, and the whole process is called as a solidification bath.

The coating parameters were: unwinding tension 32N; the extraction tension is 18N; the tension of the drying tunnel is 6N; winding tension is 2N; the speed ratio of the anilox roller is adjusted to 140%; the feeding speed is kept to be liquid return; the oven temperature averaged 50 ℃.

FIG. 1 is an electron microscope image of a para-aramid coated membrane formed by coating a para-aramid and polyetherimide blend slurry prepared in example 1; fig. 2 is an electron microscope image of a para-aramid coated membrane formed by coating the slurry prepared in comparative example 1. As can be seen from FIG. 1, the para-aramid nanofibers are completely dispersed, uniformly dispersed on the polyetherimide skeleton, and have high porosity. While in figure 2 the porosity is reduced because the lack of polyetherimide backbone results in complete bonding of the aramid fibers together. The reason is that the dissolved polyetherimide solution is added, the high-dispersion para-aramid nano-fiber is uniformly adsorbed in a polyetherimide molecular chain, and when slurry is extracted and cured, polyetherimide molecules are separated from a pore-forming agent to form a porous net to support a skeleton of the para-aramid nano-fiber, so that the whole diaphragm generates a high-temperature-resistant and high-porosity coating diaphragm.

The para-aramid coating membrane performance parameters formed by the para-aramid and polyetherimide blend slurry prepared in examples 1-3 and the para-aramid slurry prepared in comparative examples 1 and 2 are shown in the following table:

as can be seen from the above table, the air permeability and the heat shrinkage performance of the para-aramid coated membrane prepared from the para-aramid and polyetherimide blend slurry prepared in examples 1 to 3 are significantly improved compared to those of the para-aramid coated membrane prepared from the slurry prepared in comparative examples 1 to 2.

Compared with the para-aramid coated membrane formed by coating the para-aramid and polyetherimide blended slurry prepared in the embodiment 3, the para-aramid coated membrane formed by coating the slurry prepared in the comparative example 2 has the advantages that the air permeability is increased in reply, and the heat shrinkage rate is remarkably increased, mainly because the calcium chloride is added in the embodiment 3 in a large amount, free calcium ions and chloride ions occupy the positions of hydrogen and oxygen in para-aramid to eliminate hydrogen bonds between para-aramid nano fibers, and then the polybutylene glycol is used for blocking the connection between para-aramid molecules, and the polymerization between macromolecules is controlled, so that the para-aramid slurry is formed into highly-dispersed slurry which is not easy to deteriorate, the porosity of the membrane is prevented from being reduced, and the air permeability is prevented from being increased.

The para-aramid and polyetherimide blend slurry of the present invention was prepared with process parameter adjustments according to the present disclosure and exhibited substantially the same properties as in 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.