CN118418564B - Preparation method of pre-oxidized fiber short-fiber long-fiber mixed needled felt for flow cell electrode - Google Patents

Abstract

The invention belongs to the technical field of carbon fibers, and relates to a preparation method of a pre-oxidized fiber and staple fiber mixed needled felt for a flow battery electrode, wherein double bonds in 3- (3-quinoline) acrylic acid and allyldimethoxy silane form new Si-C bonds through hydrosilylation reaction to generate stable organosilicon compounds; the lithium complex and the antimony complex can form coordination bonds with quinoline ring or other functional groups such as carboxyl, ether group and the like through the metal center of the lithium complex and the antimony complex, so that the stability and the activity of the treating agent are enhanced; the needled carbon fiber preform prepared by the method has the advantages that the density of the middle layer is higher than that of the upper surface layer and the lower surface layer, when the whole preform is loaded, the middle layer plays a role in improving the strength of the variable-density preform, and the upper surface layer and the lower surface layer are small in density, good in toughness, easy to stretch and difficult to break.

Description

Preparation method of pre-oxidized short-filament and long-filament mixed needle felt for flow battery electrodes

Technical Field

The invention relates to the technical field of carbon fiber, in particular to a method for preparing a pre-oxidized short-filament and long-filament mixed needle-punched felt for liquid flow battery electrodes.

Background Art

Carbon fiber needle-punched composite materials have simple processes, strong designability and low cost. They have excellent properties such as high specific strength and high specific modulus. They can be used to manufacture irregular thermal protection components such as the leading edge of the wings of hypersonic aircraft, solid rocket engine nozzles, and aircraft brakes.

The Chinese patent application with publication number CN114654824A discloses a continuous transition layer structure fiber preform and a preparation method thereof, comprising: preparing continuous long carbon fibers and chopped carbon fibers respectively; preparing chopped carbon fiber mesh tires using chopped carbon fibers as raw materials; using ordinary continuous long carbon fibers and stretched continuous long carbon fibers to prepare ordinary continuous long carbon fiber cloth and stretched continuous long carbon fiber cloth respectively; using three types of structural units to form a continuous transition layer structure, and the structural units are symmetrically distributed along the center line of the thickness; and performing composite needling on the continuous transition layer structure from both sides to form a formed product of the continuous transition layer structure.

The Chinese patent with the authorization announcement number CN111593478B discloses a method for preparing asphalt-based general-purpose carbon fiber needle-punched felt, comprising the following steps: 1) preparing asphalt-based general-purpose carbon fiber filaments for standby use; 2) feeding the asphalt-based general-purpose carbon fiber filaments prepared in 1) into an opening machine through a feeding roller to prepare first-level asphalt-based general-purpose carbon fiber staples; 3) sending the first-level asphalt-based general-purpose carbon fiber staples prepared in 2) to a cotton box by wind, and preparing second-level asphalt-based general-purpose carbon fiber staples through the action of a conveying nail curtain; 4) sending the second-level asphalt-based general-purpose carbon fiber staples prepared in 3) to a cotton drop box, so that the second-level asphalt-based general-purpose carbon fiber staples are evenly laid on the cotton conveying curtain, and then placed in a net-forming box, and then evenly laid on the net-forming curtain, and under the action of a pre-needling machine, a pre-needled felt is prepared; 5) subjecting the pre-needled felt prepared in 4) to a multi-stage needle-punching treatment, and then trimming and winding.

The Chinese patent application with publication number CN116373398A discloses a carbon fiber needle-punched preform and its preparation method. A preparation method of a carbon fiber needle-punched preform includes the following steps: step 1, preparing carbon fiber plain cloth and carbon fiber mesh; step 2, after the turning layer unit layer is paved with a layer of carbon fiber plain cloth, it is fixed obliquely with 12K carbon fiber, and then covered with the mesh and needle-punched; step 3, after the finished layer unit layer is paved with a layer of carbon fiber plain cloth, it is fixed obliquely with 12K carbon fiber, and then hoop-wound with 12K carbon fiber, and finally covered with the mesh and needle-punched; step 4, the turning layer is obtained by stacking the turning layer unit layers in sequence through needle-punching, and the finished layer is obtained by stacking the finished layer unit layers in sequence through needle-punching, and the turning layer and the finished layer are needle-punched to obtain a carbon fiber needle-punched preform.

However, when the preform structure of carbon fiber needle felt prepared by the prior art is subjected to the CVI deposition process to prepare C/C composite materials, a bottleneck effect is easily generated, the densification speed is slow in the later stage, the surface layer of the preform is deposited quickly, and a hard shell is easily formed, which forms closed pores inside the preform. Therefore, after a certain period of deposition, the deposition needs to be interrupted to perform surface machining to eliminate this defect, resulting in a long preparation cycle and high cost.

Summary of the invention

The present invention provides a method for preparing a mixed needle-punched felt of pre-oxidized short filaments and long filaments for liquid flow battery electrodes, which is used to overcome at least one technical defect in the above-mentioned background technology.

According to one aspect of the present invention, a method for preparing a mixed needle-punched felt of pre-oxidized short and long filaments for a flow battery electrode is provided, and the operating steps are as follows:

S1: Cut the long carbon fiber into short carbon fibers of 5-8 cm, spray water and treatment agent on the short carbon fibers, the treatment agent is added in an amount of 0.08-0.7% by weight of the short carbon fibers, and the water is added in an amount of 5-8% by weight of the short carbon fibers, and dry at 40-60°C for 30-60 hours; take out and open the short carbon fibers with an opener, lay the short carbon fibers into a web; comb the short carbon fibers into a web layer; and comb the long carbon fibers into a non-wefted cloth layer;

S2: The upper and lower surface layers are made of thinner non-woven fabric layers and thicker mesh layers, which are overlapped alternately. The mesh layers and non-woven fabric layers are repeatedly needled with a barbed needle;

S3: The inner layer is made of a thicker non-woven fabric layer and a thinner mesh layer, which are overlapped alternately. The mesh layer and the non-woven fabric layer are repeatedly needled with a barbed needle.

S4: Then the surface and inner layers are repeatedly acupunctured.

Furthermore, the surface density of the short carbon fiber web layer is 100-200 g/m ² .

Furthermore, the surface density of the long carbon fiber non-woven fabric layer is 200-500 g/m ² .

Furthermore, the weight proportion of the long carbon fiber non-woven fabric in the surface layer is 30-50%.

Furthermore, the weight proportion of the long carbon fiber non-woven fabric in the inner layer is 60-80%.

Furthermore, the acupuncture density is 60-100 needles/cm ² .

Furthermore, the surface layer density is 0.4-0.5 g/cm ³ , and the inner layer density is 0.6-0.7 g/cm ³ .

According to one aspect of the present invention, a method for preparing the treating agent is provided:

H1: Take 0.02-0.5 parts of 3-(3-quinoline) acrylic acid, mix with 12-15 parts of allyldimethoxysilane and 100-120 parts of tetrahydrofuran, and react the mixture at 50-60° C. for 30-80 minutes to ensure sufficient reaction;

H2: adding 3-8 parts of diethylene glycol monoallyl ether to the above reaction mixture and adding 2-5 parts of chloroplatinic acid as a catalyst;

H3: Subsequently, 0.005-0.02 parts of lithium acrylate as a stabilizer and 0.003-0.05 parts of acrylate diphenyl antimony as a reaction regulator are added to the mixture to ensure the stability of the reaction process and the quality of the product; the mixture is continuously stirred at 50-60°C for a reaction time of 100-140 minutes; tetrahydrofuran is removed by reduced pressure distillation to obtain a treating agent.

The reaction mechanism of the technical solution of the present invention is:

1. Hydrosilylation reaction:

The double bond in 3-(3-quinoline) acrylic acid reacts with allyldimethoxysilane to form a new Si-C bond through a hydrosilylation reaction to generate a stable organosilicon compound;

2. Coordination effect:

Lithium complexes and antimony complexes can form coordination bonds with quinoline rings or other functional groups such as carboxyl groups, ether groups, etc. through their metal centers, thereby enhancing the stability and activity of the treating agent.

Compared with the prior art, the present invention has the following beneficial effects:

1. Improve the pore sealing problem on the surface of preform:

The quinoline-containing treating agent can effectively fill and cover the tiny pores on the surface of the preform through its macrocyclic structure and electronic properties, preventing further closure and helping to maintain the porosity and permeability of the material;

2. Improve product density and uniformity:

The treating agent containing diethylene glycol monoallyl ether can help other components to be evenly distributed in the material through its good solubility and wettability, reduce agglomeration and uneven distribution, and thus improve the density and overall uniformity of the product; lithium complexes and antimony complexes can enhance the interaction between the treating agent and the preform through their unique chemical properties and structures, and further improve the uniformity and density of the material;

3. The needle-punched carbon fiber preform with low surface density and high inner layer density prepared by the present invention is conducive to the deposition of reaction gas from the inside to the outside of the preform in the subsequent deposition process, which can effectively solve the problem that the pores on the surface of the preform are easily closed, not only ensuring the high density and uniformity of the product, but also shortening the preparation cycle and thus reducing the production cost;

4. The needle-punched carbon fiber preform prepared by the present invention has a middle layer density greater than that of the upper and lower surface layers. When the entire preform is under load, the middle layer plays a role in improving the strength of the variable density preform. The upper and lower surface preforms have a small density, good toughness, are easier to stretch, and are not easy to break.

DETAILED DESCRIPTION

In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description in conjunction with embodiments and comparative examples:

The actual density of the preforms was tested and compared by the drainage method; the bending mechanical properties of the preforms were tested and compared by the 3385H universal mechanical strength tester.

Example 1: A method for preparing a mixed needle-punched felt of pre-oxidized short and long filaments for a flow battery electrode, wherein the steps are as follows:

S1: Cut the long carbon fiber into 5cm short carbon fiber, spray water and treatment agent on the short carbon fiber, the treatment agent is added in an amount of 0.08% by weight of the short carbon fiber, and the water is added in an amount of 5% by weight of the short carbon fiber, and dry at 40°C for 30h; take out and open it with an opener, lay the short carbon fiber into a mesh; comb the short carbon fiber into a mesh layer; comb the long carbon fiber into a non-weft cloth layer;

S2: The upper and lower surface layers are made of thinner non-woven fabric layers and thicker mesh layers, which are overlapped alternately. The mesh layers and non-woven fabric layers are repeatedly needled with a barbed needle;

S3: The inner layer is made of a thicker non-woven fabric layer and a thinner mesh layer, which are overlapped alternately. The mesh layer and the non-woven fabric layer are repeatedly needled with a barbed needle.

S4: Then the surface and inner layers are repeatedly acupunctured.

The surface density of the short carbon fiber web layer is 100 g/m ² .

The surface density of the long carbon fiber non-woven fabric layer is 200 g/m ² .

The weight proportion of the long carbon fiber non-woven fabric in the surface layer is 30%.

The weight proportion of the long carbon fiber non-woven fabric in the inner layer is 60%.

The needle punching density is 60 needles/cm ² .

The surface layer density is 0.4 g/cm ³ , and the inner layer density is 0.6 g/cm ³ .

The preparation method of the treating agent is:

H1: 0.02 g of 3-(3-quinoline)acrylic acid was mixed with 12 g of allyldimethoxysilane and 100 g of tetrahydrofuran, and the mixture was reacted at 50° C. for 30 minutes to ensure sufficient reaction;

H2: 3 g of diethylene glycol monoallyl ether was added to the above reaction mixture, and 2 g of chloroplatinic acid was added as a catalyst;

H3: Subsequently, 0.005 g of lithium acrylate as a stabilizer and 0.003 g of acrylated diphenyl antimony as a reaction regulator were added to the mixture to ensure the stability of the reaction process and the quality of the product; the mixture was continuously stirred at 50°C for 100 minutes; tetrahydrofuran was removed by reduced pressure distillation to obtain a treating agent.

Example 2: A method for preparing a mixed needle-punched felt of pre-oxidized short and long filaments for a flow battery electrode, wherein the steps are as follows:

S1: Cut the long carbon fiber into 6cm short carbon fiber, spray water and treatment agent on the short carbon fiber, the treatment agent is added in an amount of 0.2% by weight of the short carbon fiber, and the water is added in an amount of 6% by weight of the short carbon fiber, and dry at 45°C for 40h; take out and open it with an opener, lay the short carbon fiber into a mesh; comb the short carbon fiber into a mesh layer; comb the long carbon fiber into a non-weft cloth layer;

S2: The upper and lower surface layers are made of thinner non-woven fabric layers and thicker mesh layers, which are overlapped alternately. The mesh layers and non-woven fabric layers are repeatedly needled with a barbed needle;

S3: The inner layer is made of a thicker non-woven fabric layer and a thinner mesh layer, which are overlapped alternately. The mesh layer and the non-woven fabric layer are repeatedly needled with a barbed needle.

S4: Then the surface and inner layers are repeatedly acupunctured.

The surface density of the short carbon fiber web layer is 140 g/m ² .

The surface density of the long carbon fiber non-woven fabric layer is 300 g/m ² .

The weight proportion of the long carbon fiber non-woven fabric in the surface layer is 35%.

The weight proportion of the long carbon fiber non-woven fabric in the inner layer is 65%.

The needle punching density is 70 needles/cm ² .

The surface layer density is 0.4 g/cm ³ , and the inner layer density is 0.6 g/cm ³ .

The preparation method of the treating agent is:

H1: 0.2 g of 3-(3-quinoline)acrylic acid was mixed with 13 g of allyldimethoxysilane and 105 g of tetrahydrofuran, and the mixture was reacted at 55° C. for 50 minutes to ensure sufficient reaction;

H2: 4 g of diethylene glycol monoallyl ether was added to the above reaction mixture, and 3 g of chloroplatinic acid was added as a catalyst;

H3: Subsequently, 0.01 g of lithium acrylate as a stabilizer and 0.02 g of acrylated antimony diphenyl as a reaction regulator were added to the mixture to ensure the stability of the reaction process and the quality of the product; the mixture was continuously stirred at 55°C for 110 minutes; tetrahydrofuran was removed by reduced pressure distillation to obtain a treating agent.

Example 3: A method for preparing a mixed needle-punched felt of pre-oxidized short and long filaments for a flow battery electrode, wherein the steps are as follows:

S1: Cut the long carbon fiber into 7 cm short carbon fiber, spray water and treatment agent on the short carbon fiber, the treatment agent is added in an amount of 0.5% by weight of the short carbon fiber, and the water is added in an amount of 7% by weight of the short carbon fiber, and dry at 55°C for 50 hours; take out and open it with an opener, and lay the short carbon fiber into a mesh; comb the short carbon fiber into a mesh layer; comb the long carbon fiber into a non-weft cloth layer;

S2: The upper and lower surface layers are made of thinner non-woven fabric layers and thicker mesh layers, which are overlapped alternately. The mesh layers and non-woven fabric layers are repeatedly needled with a barbed needle;

S3: The inner layer is made of a thicker non-woven fabric layer and a thinner mesh layer, which are overlapped alternately. The mesh layer and the non-woven fabric layer are repeatedly needled with a barbed needle.

S4: Then the surface and inner layers are repeatedly acupunctured.

The surface density of the short carbon fiber web layer is 180 g/m ² .

The surface density of the long carbon fiber non-woven fabric layer is 400 g/m ² .

The weight proportion of the long carbon fiber non-woven fabric in the surface layer is 45%.

The weight proportion of the long carbon fiber non-woven fabric in the inner layer is 75%.

The needle punching density is 90 needles/cm ² .

The surface layer density is 0.5 g/cm ³ , and the inner layer density is 0.7 g/cm ³ .

The preparation method of the treating agent is:

H1: 0.4 g of 3-(3-quinoline)acrylic acid was mixed with 14 g of allyldimethoxysilane and 115 g of tetrahydrofuran, and the mixture was reacted at 55° C. for 70 minutes to ensure sufficient reaction;

H2: 7 g of diethylene glycol monoallyl ether was added to the above reaction mixture, and 4 g of chloroplatinic acid was added as a catalyst;

H3: Subsequently, 0.015 g of lithium acrylate as a stabilizer and 0.04 g of acrylated diphenyl antimony as a reaction regulator were added to the mixture to ensure the stability of the reaction process and the quality of the product; the mixture was continuously stirred at 55°C for 130 minutes; tetrahydrofuran was removed by reduced pressure distillation to obtain a treating agent.

Example 4: A method for preparing a mixed needle-punched felt of pre-oxidized short and long filaments for a flow battery electrode, wherein the steps are as follows:

S1: Cut the long carbon fiber into 8cm short carbon fiber, spray water and treatment agent on the short carbon fiber, the treatment agent is added in an amount of 0.7% by weight of the short carbon fiber, and the water is added in an amount of 8% by weight of the short carbon fiber, and dry at 60°C for 60h; take out and open it with an opener, lay the short carbon fiber into a web; comb the short carbon fiber into a web layer; comb the long carbon fiber into a non-weft cloth layer;

S2: The upper and lower surface layers are made of thinner non-woven fabric layers and thicker mesh layers, which are overlapped alternately. The mesh layers and non-woven fabric layers are repeatedly needled with a barbed needle;

S3: The inner layer is made of a thicker non-woven fabric layer and a thinner mesh layer, which are overlapped alternately. The mesh layer and the non-woven fabric layer are repeatedly needled with a barbed needle.

S4: Then the surface and inner layers are repeatedly acupunctured.

The surface density of the short carbon fiber web layer is 200 g/m ² .

The surface density of the long carbon fiber non-woven fabric layer is 500 g/m ² .

The weight proportion of the long carbon fiber non-woven fabric in the surface layer is 50%.

The weight proportion of the long carbon fiber non-woven fabric in the inner layer is 80%.

The needle punching density is 100 needles/cm ² .

The surface layer density is 0.5 g/cm ³ , and the inner layer density is 0.7 g/cm ³ .

The preparation method of the treating agent is:

H1: 0.5 g of 3-(3-quinoline)acrylic acid was mixed with 15 g of allyldimethoxysilane and 120 g of tetrahydrofuran, and the mixture was reacted at 60° C. for 80 minutes to ensure sufficient reaction;

H2: 8 g of diethylene glycol monoallyl ether was added to the above reaction mixture, and 5 g of chloroplatinic acid was added as a catalyst;

H3: Subsequently, 0.02 g of lithium acrylate as a stabilizer and 0.05 g of acrylated diphenyl antimony as a reaction regulator were added to the mixture to ensure the stability of the reaction process and the quality of the product; the mixture was continuously stirred at 60°C for 140 minutes; tetrahydrofuran was removed by reduced pressure distillation to obtain a treating agent.

Comparative Example 1: For comparison, no treatment agent was added in this example, and the rest was the same as in Example 1.

Comparative Example 2: For comparison, allyldimethoxysilane was not added in this example, and the other conditions were the same as those in Example 1.

Comparative Example 3: For comparison, in this example, 3-(3-quinoline)acrylic acid was not added, and the rest was the same as in Example 1.

Table 1: Test results of various embodiments and comparative examples

Through the data analysis of the above embodiments and comparative examples, the treating agent prepared by the present invention can effectively improve the uniformity and density of the material; at the same time, it can improve the toughness of the material and make it less likely to break.

Finally, it should be noted that the specific embodiments described herein are merely examples of the present invention, and are not intended to limit the implementation methods of the present invention. Those skilled in the art of the present invention may make various modifications or additions to the specific embodiments described, or replace them in a similar manner. It is not necessary and impossible to provide all examples of all implementation methods here. However, these obvious changes or modifications derived from the essential spirit of the present invention still fall within the scope of protection of the present invention, and interpreting them as any additional limitation is contrary to the spirit of the present invention.

Claims (5)

1. The preparation method of the pre-oxidized fiber and staple fiber mixed needled felt for the flow cell electrode is characterized by comprising the following steps of: the operation steps are as follows:

s1: cutting long carbon fibers into short carbon fibers with the length of 5-8cm, spraying water and a treating agent on the short carbon fibers, wherein the adding amount of the treating agent is 0.08-0.7% by weight of the short carbon fibers, the adding amount of the water is 5-8% by weight of the short carbon fibers, and drying at 40-60 ℃ for 30-60h; taking out and opening by an opener, and paving the short carbon fibers into a net tire; carding the short carbon fibers into a net tire layer; carding long carbon fibers into a non-woven cloth layer;

S2: the upper surface layer and the lower surface layer are alternately overlapped by adopting a thinner non-woven fabric layer and a thicker net tire layer, and the net tire layer and the non-woven fabric layer are repeatedly needled by using a needling needle with a barb;

S3: the inner layer adopts a thicker non-woven fabric layer and a thinner net tire layer, which are overlapped alternately, and the net tire layer and the non-woven fabric layer are needled repeatedly by a needling needle with a barb;

s4: then repeatedly needling the surface layer and the inner layer;

The long carbon fiber laid cloth accounts for 30-50% of the weight of the surface layer;

the long carbon fiber laid fabric accounts for 60-80% of the weight of the inner layer;

the preparation method of the treating agent comprises the following steps:

H1: taking 0.02-0.5 part of 3- (3-quinoline) acrylic acid according to parts by weight, mixing with 12-15 parts of allyldimethoxy silane and 100-120 parts of tetrahydrofuran, reacting the mixture at 50-60 ℃ for 30-80 minutes to ensure full reaction;

H2: adding 3-8 parts of diethylene glycol monoallyl ether into the mixture, and adding 2-5 parts of chloroplatinic acid as a catalyst;

And H3: then adding 0.005-0.02 part of lithium acrylate as a stabilizer and 0.003-0.05 part of oxydiphenyl antimony acrylate as a reaction regulator into the mixture to ensure the stability of the reaction process and the quality of the product; stirring the mixture continuously at 50-60 ℃ for a reaction time of 100-140 minutes; tetrahydrofuran was removed by distillation under reduced pressure to obtain a treating agent.

2. The method for preparing the pre-oxidized fiber and staple fiber mixed needled felt for the flow cell electrode, which is characterized in that: the surface density of the chopped carbon fiber net tire layer is 100-200g/m ².

3. The method for preparing the pre-oxidized fiber and staple fiber mixed needled felt for the flow cell electrode, which is characterized in that: the surface density of the long carbon fiber laid fabric layer is 200-500g/m ².

4. The method for preparing the pre-oxidized fiber and staple fiber mixed needled felt for the flow cell electrode, which is characterized in that: the needling density is 60-100 needles/cm ².

5. The method for preparing the pre-oxidized fiber and staple fiber mixed needled felt for the flow cell electrode, which is characterized in that: the density of the surface layer is 0.4-0.5g/cm ³, and the density of the inner layer is 0.6-0.7g/cm ³.