Preparation method of aramid-based graphene conductive composite electromagnetic shielding material

Abstract

The invention discloses a preparation method of an aramid-based graphene conductive composite electromagnetic shielding material, and relates to the technical field of composite aramid paper, and the preparation method comprises the following preparation steps: step 1, preparing graphene oxide; 2, graphene oxide is poured into deionized water, and a graphene oxide solution with the concentration being 0.1 mg / mL to 1 mg / mL is prepared; and step 3, preparing the graphene oxide aramid paper composite material by using a layer-by-layer self-assembly method. According to the preparation method of the aramid-based graphene conductive composite electromagnetic shielding material, graphene oxide is used as a precursor and a supporting carrier for synthesizing a graphene-based composite material, functionalization is easy, controllability is high, and in the compounding process with materials such as high-molecular polymers, a large specific surface area can be provided, an attached material can be effectively dispersed, and agglomeration is prevented; meanwhile, due to introduction of oxygen-containing groups, graphene oxide has chemical stability, surface modification active sites are provided for synthesis of graphene-based / graphene oxide-based aramid paper, and the specific surface area of the graphene-based / graphene oxide-based aramid paper is enlarged.

Description

Technical Field

[0001] The invention relates to the technical field of composite aramid paper, in particular to a method for preparing an aramid-based graphene conductive composite electromagnetic shielding material. Background Art

[0002] The Chinese patent with the publication number CN108486949A discloses a method for preparing a multi-layer composite aramid paper, wherein the aramid paper comprises two or more fiber layers, and comprises the following steps: mixing each fiber layer with the required pulp and short-cut fibers respectively, and the length and fineness of the short-cut fibers in the fibers are different to form papermaking pulp; using a multi-layer headstock box to flow out the pulp of different fiber layers respectively, and forming on the net; the wet paper web is compounded in sequence according to each fiber layer, and the paper is pressed and dried by a vacuum pressing roller; the paper is heated; a second rolling is performed, and then the rough paper is obtained after high-temperature drying; finally, the rough paper is calendered at high temperature to obtain the finished fiber paper. The preparation method of the multi-layer composite aramid paper of the invention can control the fiber distribution of the fiber paper sheet, has high molding uniformity, high mechanical strength, good surface calendering performance, and smooth surface. However, the conductive performance of the composite aramid paper prepared by the above-mentioned prior art scheme needs to be further improved; for this reason, the present invention provides a preparation method of an aramid-based graphene conductive composite electromagnetic shielding material to solve the above-mentioned problem. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method for preparing an aramid-based graphene conductive composite electromagnetic shielding material, which solves the problems mentioned in the above background technology.

[0004] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for preparing an aramid-based graphene conductive composite electromagnetic shielding material, comprising the following preparation steps:

[0005] Step 1, preparing graphene oxide;

[0006] Step 2: pouring graphene oxide into deionized water to prepare a graphene oxide solution with a concentration of 0.1-1 mg / mL;

[0007] Step 3: Prepare graphene oxide aramid paper composite material using layer-by-layer self-assembly method, the specific operation is as follows:

[0008] (1) One piece is 60g / cm 2 The composite aramid paper is sequentially immersed in a cationic surfactant for 22-24 hours, and then immersed in a graphene oxide solution for 22-24 hours as an assembly cycle. After completing the preset number of assembly cycles, a sheet with a weight of 60g / cm 2The composite aramid paper and the assembled composite material are placed in a cationic surfactant and soaked for 22-24 hours to obtain the composite paper;

[0009] (2) The composite paper is further processed to obtain an aramid-based graphene conductive composite electromagnetic shielding material.

[0010] Preferably, the treatment method in (2) comprises: heating the composite paper to 200-350° C. in a vacuum or nitrogen environment and reducing it for 1-3 hours.

[0011] Preferably, the treatment method in (2) comprises: soaking the composite paper in hydroiodic acid at 70-90° C. for 1-3 hours, then neutralizing it in a sodium hydroxide solution, and finally washing and drying it.

[0012] Preferably, in step three (1), the cationic surfactant is selected from a cationic polyacrylamide and a polyvinyl pyrrolidone aqueous solution.

[0013] Preferably, in step 1, the preparation method of graphene oxide is:

[0014] Ⅰ. Pour 1-2.5g of natural graphite into 17-30mL of acidic solution;

[0015] Ⅱ. Add 6-10g potassium permanganate in small amounts and stir in an ice water bath for 50-60 minutes;

[0016] III. After heating to 45-55°C, keep warm for 10-12 hours;

[0017] IV. Pour the reaction product into ice water at 0-2°C and add hydrogen peroxide under stirring until the solution turns golden yellow;

[0018] V. Filter, and then wash the product with 3%-5% by volume dilute hydrochloric acid and distilled water until the pH value is 6.8-7;

[0019] VI. Pour the washed product into deionized water, ultrasonically treat for 6.5-8 hours, and then place in a vacuum drying oven at 50-60° C. and dry for 30-50 minutes to obtain graphene oxide.

[0020] Preferably, in said Ⅰ, the acid solution is a mixed solution of concentrated H2SO4 and H3PO4, and the volume ratio of concentrated H2SO4 to H3PO4 is (8-9):1.

[0021] Preferably, in step 3 (1), the preparation method of the composite aramid paper is:

[0022] S1, pouring 2-5 g of aramid nanofibers into 200 mL of deionized water to prepare an aramid nanofiber suspension;

[0023] S2, pour 3.5-6.5g of aramid pulp into 200mL of deionized water, and deflocculate in a fiber deflocculant for 20-30min to prepare an aramid pulp suspension;

[0024] S3, mixing the aramid nanofiber suspension and the aramid pulp suspension, stirring them fully for 10-12 hours, and then placing them in a vacuum drying oven for degassing for 1.5-2 hours;

[0025] S4. Use a circulating water vacuum pump to filter it into a semi-dry state and take it out. Place it in a vacuum drying oven at 60-65°C with the four corners clamped and flattened to dry for 40-48 hours, and then use a flat vulcanizer to press it for 20-30 minutes to obtain the composite aramid paper.

[0026] Preferably, the temperature of the plate vulcanizer is 200-220° C., and the pressure is 15.6-16.2 MPa.

[0027] Preferably, the preparation method of the aramid nanofiber is:

[0028] S11, cutting the para-aramid into fibers with a length of 8-10 cm, soaking them in acetone for 20-24 hours and then drying them;

[0029] S12, pour 1-1.5 g of aramid fiber and 1-1.5 g of potassium tert-butoxide into 480-510 mL of a mixed solvent, and stir magnetically for 40-48 hours to obtain a solution A;

[0030] S13, adding deionized water of the same volume to solution A, and stirring at a speed of 600-800 r / min for 20-35 min;

[0031] S14, vacuum filtering the solution, washing the solid with acetone for 3-5 times and drying it to obtain aramid nanofibers.

[0032] Preferably, in S12, the mixed solvent is a mixed solution of dimethyl sulfoxide and methanol, and the volume ratio thereof is (485-500):1.

[0033] Beneficial Effects

[0034] The present invention provides a method for preparing an aramid-based graphene conductive composite electromagnetic shielding material. Compared with the prior art, the method has the following beneficial effects:

[0035] (1) The preparation method of the aramid-based graphene conductive composite electromagnetic shielding material uses graphene oxide as a precursor and supporting carrier for synthesizing graphene-based composite materials, which is easy to functionalize and has high controllability. In the process of compounding with materials such as high molecular polymers, it can provide a large specific surface area, effectively disperse the attached materials, and prevent agglomeration; at the same time, the introduction of oxygen-containing groups not only makes the graphene oxide chemically stable, but also provides surface modification active sites for synthesizing graphene-based / graphene oxide-based aramid paper and expands its specific surface area. Through the conjugated large π bond force between the two-dimensional nanocomposite material and the aramid amide polymer chain segment, and by utilizing the synergistic effect of the composite material, the conductive performance and electromagnetic shielding performance of the material are improved.

[0036] (2) The preparation method of the aramid-based graphene conductive composite electromagnetic shielding material is to fill the pores in the aramid pulp suspension with an aramid nanofiber suspension to achieve bonding between adjacent fibers, enhance the reflection of electromagnetic waves on the surface of the material, reduce the gaps and defects between the fibers, and make the porosity of the composite paper smaller and the pore distribution more uniform. After being composited with graphene, the absorption effect of the electromagnetic waves inside the material is increased; while strengthening the composite material, there are more polar units such as amide, amino and carboxyl on the surface of the nano-aramid fiber, which can significantly improve the conductivity and thermal stability of the composite paper, and there is a hydrogen bond between these polar units and the aramid pulp suspension, so that the aramid pulp matrix and the aramid nanofibers have a strong bonding effect, thereby improving the mechanical properties of the composite paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a comparison chart of the thermal stability test provided by the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the technical scheme, the preparation method of aramid nanofiber is as follows: cut para-aramid into fibers with a length of 10 cm, soak them in acetone for 24 hours and then dry them; pour 1.5 g of aramid and 1.5 g of potassium tert-butoxide into 510 mL of a mixed solution of dimethyl sulfoxide and methanol with a volume ratio of 500:1, and stir them magnetically for 48 hours to obtain solution A; add deionized water with the same volume as solution A, and stir at a speed of 800 r / min for 30 minutes; vacuum filter the solution, wash the solid with acetone 4 times and then dry it to obtain aramid nanofiber.

[0040] Example 1

[0041] A method for preparing an aramid-based graphene conductive composite electromagnetic shielding material comprises the following preparation steps:

[0042] Step 1, preparation of graphene oxide: pour 1g of natural graphite into 17mL of a mixed solution of concentrated H2SO4 and H3PO4 with a volume ratio of 8:1; add 6g of potassium permanganate in small amounts and multiple times, and stir in an ice water bath for 50min; after heating to 45°C, keep the reaction for 10h; pour the reaction product into 0°C ice water, and add hydrogen peroxide under stirring until the color of the solution turns golden yellow; filter, and then use 3% volume fraction of dilute hydrochloric acid and distilled water to wash the product until its pH value is 6.8; pour the washed product into deionized water, ultrasonically treat for 6.5h, and then place it in a vacuum drying oven at 50°C for 30min to obtain graphene oxide;

[0043] Step 2: Pour graphene oxide into deionized water to prepare a graphene oxide solution with a concentration of 0.1 mg / mL;

[0044] Step 3: Prepare graphene oxide aramid paper composite material using layer-by-layer self-assembly method, the specific operation is as follows:

[0045] (1) One piece is 60g / cm 2 The composite aramid paper was immersed in cationic polyacrylamide for 22 hours, and then immersed in graphene oxide solution for 22 hours as an assembly cycle. After completing 7 assembly cycles, a sheet with a weight of 60g / cm 2 The composite aramid paper and the assembled composite material are placed in a cationic surfactant and soaked for 22-24 hours to obtain the composite paper;

[0046] (2) In a vacuum or nitrogen environment, the composite paper is heated to 200° C. and reduced for 1 hour to obtain an aramid-based graphene conductive composite electromagnetic shielding material.

[0047] The preparation method of the composite aramid paper is as follows: pour 2 g of aramid nanofiber into 200 mL of deionized water to prepare an aramid nanofiber suspension; pour 3.5 g of aramid pulp into 200 mL of deionized water, and deflate in a fiber deflagrator for 20 minutes to prepare an aramid pulp suspension; mix the aramid nanofiber suspension and the aramid pulp suspension, stir them fully for 10 hours, and then place them in a vacuum drying oven for degassing for 1.5 hours; use a circulating water vacuum pump to filter them into a semi-dry state, take them out, and place them in a vacuum drying oven at 60°C with the four corners clamped and flattened for 40 hours, and then press them for 20 minutes using a flat vulcanizer at a temperature of 200°C and a pressure of 15.6 MPa to obtain the composite aramid paper.

[0048] Example 2

[0049] A method for preparing an aramid-based graphene conductive composite electromagnetic shielding material comprises the following preparation steps:

[0050] Step 1, preparation of graphene oxide: pour 1.5g of natural graphite into 18mL of a mixed solution of concentrated H2SO4 and H3PO4 with a volume ratio of 8.5:1; add 8g of potassium permanganate in small amounts and multiple times, and stir in an ice water bath for 55min; after heating to 50°C, keep warm for 11h; pour the reaction product into 1°C ice water, and add hydrogen peroxide under stirring until the color of the solution turns golden yellow; filter, and then use 4% volume fraction of dilute hydrochloric acid and distilled water to wash the product until its pH value is 6.9; pour the washed product into deionized water, ultrasonically treat for 7h, and place it in a vacuum drying oven at 55°C for 40min to obtain graphene oxide;

[0051] Step 2: Pour graphene oxide into deionized water to prepare a graphene oxide solution with a concentration of 0.5 mg / mL;

[0052] Step 3: Prepare graphene oxide aramid paper composite material using layer-by-layer self-assembly method, the specific operation is as follows:

[0053] (1) One piece is 60g / cm 2 The composite aramid paper was immersed in a cationic surfactant for 23 hours, and then immersed in a graphene oxide solution for 23 hours as an assembly cycle. After completing 5 assembly cycles, a sheet with a weight of 60 g / cm 2 The composite aramid paper and the assembled composite material are placed in a cationic surfactant and soaked for 22-24 hours to obtain the composite paper;

[0054] (2) The composite paper is immersed in hydroiodic acid at 80° C. for 2 h, then neutralized in a sodium hydroxide solution, and finally washed and dried to obtain an aramid-based graphene conductive composite electromagnetic shielding material.

[0055] The preparation method of the composite aramid paper is as follows: 3 g of aramid nanofiber is poured into 200 mL of deionized water to prepare an aramid nanofiber suspension; 4.5 g of aramid pulp is poured into 200 mL of deionized water, and is deflated in a fiber deflagrator for 25 minutes to prepare an aramid pulp suspension; the aramid nanofiber suspension and the aramid pulp suspension are mixed and stirred for 11 hours, and then placed in a vacuum drying oven for degassing for 1.8 hours; the semi-dry state is filtered out using a circulating water vacuum pump, and the mixture is placed in a vacuum drying oven at 62°C with the four corners clamped and flattened for 44 hours, and then pressed for 25 minutes using a flat vulcanizer at a temperature of 210°C and a pressure of 15.8 MPa to obtain the composite aramid paper.

[0056] Example 3

[0057] A method for preparing an aramid-based graphene conductive composite electromagnetic shielding material comprises the following preparation steps:

[0058] Step 1, preparation of graphene oxide: pour 2.5g of natural graphite into 30mL of a mixed solution of concentrated H2SO4 and H3PO4 with a volume ratio of 9:1; add 10g of potassium permanganate in small amounts and multiple times, and stir in an ice water bath for 60min; after heating to 55°C, keep warm for 12h; pour the reaction product into 2°C ice water, and add hydrogen peroxide under stirring until the color of the solution turns golden yellow; filter, and then use 5% volume fraction of dilute hydrochloric acid and distilled water to wash the product until its pH value is 7; pour the washed product into deionized water, ultrasonically treat for 8h, and then place it in a vacuum drying oven at 60°C for 50min to obtain graphene oxide;

[0059] Step 2: Pour graphene oxide into deionized water to prepare a graphene oxide solution with a concentration of 1 mg / mL;

[0060] Step 3: Prepare graphene oxide aramid paper composite material using layer-by-layer self-assembly method, the specific operation is as follows:

[0061] (1) One piece is 60g / cm 2 The composite aramid paper was immersed in a polyvinyl pyrrolidone aqueous solution for 24 hours, and then immersed in a graphene oxide solution for 24 hours as an assembly cycle. After completing three assembly cycles, a sheet with a weight of 60 g / cm 2 The composite aramid paper and the assembled composite material are placed together in a cationic surfactant and immersed for 24 hours to obtain the composite paper; (2) the composite paper is placed in 90°C hydroiodic acid and immersed for 3 hours, and then neutralized in a sodium hydroxide solution, and finally washed and dried to obtain the aramid-based graphene conductive composite electromagnetic shielding material.

[0062] The preparation method of the composite aramid paper is as follows: pour 5 g of aramid nanofiber into 200 mL of deionized water to prepare an aramid nanofiber suspension; pour 6.5 g of aramid pulp into 200 mL of deionized water, and deflate in a fiber deflagrator for 30 minutes to prepare an aramid pulp suspension; mix the aramid nanofiber suspension and the aramid pulp suspension, stir them fully for 12 hours, and then place them in a vacuum drying oven for degassing for 2 hours; use a circulating water vacuum pump to filter them into a semi-dry state, take them out, and place them in a vacuum drying oven at 65°C with the four corners clamped and flattened for 48 hours, and then use a flat vulcanizer at a temperature of 220°C and a pressure of 16.2 MPa to press for 30 minutes to obtain the composite aramid paper.

[0063] Comparative Example 1

[0064] Compared with Example 1, the difference is that no aramid nanofiber suspension is added during the preparation of the composite aramid paper; the rest remains unchanged.

[0065] Comparative Example 2

[0066] Compared with Example 1, the difference is that the composite paper is not further processed; the rest remains unchanged.

[0067] Comparative Example 3

[0068] Compared with Example 1, graphene oxide is not added during the preparation process of the composite aramid paper; the rest remains unchanged.

[0069] Mechanical properties test: According to GB / T 12914 standard, the tensile strength and elongation at break of the sample were measured using a paper tensile strength tester.

[0070] Electrical performance test: Tested according to GB / T 1408.1.

[0071] Resistivity test: Tested according to GB / T 10581-2006 standard.

[0072] Electromagnetic shielding effectiveness: tested according to GJB 6190-2008 standard, the data in the table are tested under 10GHz conditions.

[0073]

[0074] Thermal stability test: The composite paper was tested in N2 atmosphere at a temperature of 25-950°C and a heating rate of 10°C / min. Figure 1 As shown: compared with comparative examples 1-3, the thermal weight loss rate of the composite aramid paper prepared in examples 1-3 is slower and its thermal stability is better.

[0075] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0076] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0077] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an aramid-based graphene conductive composite electromagnetic shielding material, characterized in that: The method comprises the following preparation steps: Step 1, preparing graphene oxide; Step 2: pouring graphene oxide into deionized water to prepare a graphene oxide solution with a concentration of 0.1-1 mg / mL; Step 3: Prepare graphene oxide aramid paper composite material using layer-by-layer self-assembly method, the specific operation is as follows: (1) One piece is 60g / cm 2 The composite aramid paper is sequentially immersed in a cationic surfactant for 22-24 hours, and then immersed in a graphene oxide solution for 22-24 hours as an assembly cycle. After completing the preset number of assembly cycles, a sheet with a weight of 60g / cm 2 The composite aramid paper and the assembled composite material are placed in a cationic surfactant and soaked for 22-24 hours to obtain the composite paper; (2) the composite paper is further treated to obtain the aramid-based graphene conductive composite electromagnetic shielding material.

2. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 1, characterized in that: The treatment method in (2) includes: heating the composite paper to 200-350° C. in a vacuum or nitrogen environment and reducing it for 1-3 hours.

3. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 1, characterized in that: The treatment method in (2) comprises: soaking the composite paper in hydroiodic acid at 70-90° C. for 1-3 hours, then neutralizing it in a sodium hydroxide solution, and finally washing and drying it.

4. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 1, characterized in that: In step 3 (1), the cationic surfactant is selected from a cationic polyacrylamide and a polyvinyl pyrrolidone aqueous solution.

5. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 1, characterized in that: In the step 1, the preparation method of graphene oxide is: Ⅰ. Pour 1-2.5g of natural graphite into 17-30mL of acidic solution; Ⅱ. Add 6-10g potassium permanganate in small amounts and stir in an ice water bath for 50-60 minutes; III. After heating to 45-55°C, keep warm for 10-12 hours; IV. Pour the reaction product into ice water at 0-2°C and add hydrogen peroxide under stirring until the solution turns golden yellow; V. Filter, and then wash the product with 3%-5% by volume dilute hydrochloric acid and distilled water until the pH value is 6.8-7; VI. Pour the washed product into deionized water, ultrasonically treat for 6.5-8 hours, and then place in a vacuum drying oven at 50-60° C. and dry for 30-50 minutes to obtain graphene oxide.

6. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 5, characterized in that: In said Ⅰ, the acid solution is a mixed solution of concentrated H2SO4 and H3PO4, and the volume ratio of concentrated H2SO4 to H3PO4 is (8-9):

1.

7. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 1, characterized in that: In step 3 (1), the preparation method of the composite aramid paper is: S1, pouring 2-5 g of aramid nanofibers into 200 mL of deionized water to prepare an aramid nanofiber suspension; S2, pour 3.5-6.5g of aramid pulp into 200mL of deionized water, and deflocculate in a fiber deflocculant for 20-30min to prepare an aramid pulp suspension; S3, mixing the aramid nanofiber suspension and the aramid pulp suspension, stirring them fully for 10-12 hours, and then placing them in a vacuum drying oven for degassing for 1.5-2 hours; S4. Use a circulating water vacuum pump to filter it into a semi-dry state and take it out. Place it in a vacuum drying oven at 60-65°C with the four corners clamped and flattened to dry for 40-48 hours, and then use a flat vulcanizer to press it for 20-30 minutes to obtain the composite aramid paper.

8. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 7, characterized in that: The temperature of the flat vulcanizing press is 200-220° C., and the pressure is 15.6-16.2 MPa.

9. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 7, characterized in that: The preparation method of the aramid nanofiber is: S11, cutting the para-aramid into fibers with a length of 8-10 cm, soaking them in acetone for 20-24 hours and then drying them; S12, pour 1-1.5 g of aramid fiber and 1-1.5 g of potassium tert-butoxide into 480-510 mL of a mixed solvent, and stir magnetically for 40-48 hours to obtain a solution A; S13, adding deionized water of the same volume to solution A, and stirring at a speed of 600-800 r / min for 20-35 min; S14, vacuum filtering the solution, washing the solid with acetone for 3-5 times and drying it to obtain aramid nanofibers.

10. The method for preparing an aramid-based graphene conductive composite electromagnetic shielding material according to claim 9, characterized in that: In the S12, the mixed solvent is a mixed solution of dimethyl sulfoxide and methanol, and the volume ratio thereof is (485-500):1.

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