Preparation method of graphene conductive cloth black shielding film with anti-corrosion function

Abstract

The invention relates to the technical field of electromagnetic shielding materials, in particular to a preparation method of a graphene conductive cloth black shielding film with an anti-corrosion function, and the graphene conductive cloth black shielding film comprises a conductive cloth substrate and a composite metal coating deposited on the surface of the conductive cloth substrate, the composite metal plating layer is coated with a two-way glue solution, the surface of the composite metal plating layer is coated with the two-way glue solution, the surface of the two-way glue solution is coated with the graphene outer layer in a dip-coating mode, the surface of the graphene outer layer is coated with the self-repairing coating, and the super-hydrophobic coating is sprayed to the surface of the self-repairing coating. The adhesive force between the graphene and the substrate is remarkably improved, and the problem of interlayer stripping of a traditional material is solved; and protection of a metal coating is facilitated, a sandwich structure is formed to be combined with the self-repairing corrosion inhibition coating, triple protection of metal blocking, graphene shielding and corrosion inhibitor release is formed, and the corrosion rate of the coating is reduced by 90% or above.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electromagnetic shielding materials, in particular to a preparation method of a graphene conductive cloth black shielding film with corrosion resistance. BACKGROUND

[0002] In the current development of material science and electronic technology, the combination material of graphene and a conductive cloth substrate has broad application prospects in many fields, such as electromagnetic shielding of electronic equipment, corrosion-resistant materials in the field of aerospace, and protective coatings in marine engineering. At present, the common conductive cloth substrate is mainly a nickel or copper fiber cloth, and the combination mode of graphene and the conductive cloth substrate is mainly physical adsorption. However, this combination mode has obvious defects. When subjected to harsh environments such as water vapor and salt spray for a long time, interlayer peeling between the two is prone to occur. For example, the graphene film prepared by the traditional padding method is placed in a 5% NaCl solution for 72 hours, and the graphene shedding area can reach 40%, so that the corrosion protection effect is almost lost. Once interlayer peeling occurs, the corrosion medium can directly contact the substrate metal plating layer, thereby causing a series of subsequent corrosion problems.

[0003] From the characteristics of the conductive cloth substrate itself, the nickel or copper plating layer on the surface has poor stability in complex environments. In a sulfur-containing environment, the nickel plating layer will undergo an electrochemical reaction to generate a loose NiS corrosion layer. This loose structure cannot effectively block the further intrusion of external corrosion medium, making the corrosion situation even worse. In a high humidity environment, the copper plating layer will form Cu2(OH)2CO3, which is the familiar green copper. The presence of green copper not only destroys the original conductive network on the surface of the conductive cloth, but also accelerates the corrosion process of the substrate, greatly reducing the service life and performance of the conductive cloth.

[0004] Looking at the existing shielding film, its protection mechanism mainly depends on the single-layer barrier effect of graphene. However, this single protection mode has a fatal weakness. When graphene layer has defects such as microcracks during processing, the corrosion medium will quickly penetrate the substrate along these defects. Due to the lack of other effective synergistic protection mechanisms, once the corrosion medium contacts the substrate, localized corrosion will spread at an extremely fast speed, thereby causing serious damage to the performance of the entire material.

[0005] In summary, the current combination material of graphene and a conductive cloth substrate has many problems to be solved in terms of corrosion resistance, stability and protection mechanism, and it is of great practical significance and market demand to develop a new material or preparation method that can effectively solve the above problems. SUMMARY

[0006] The present application is to overcome the above-mentioned deficiencies, and aims to provide a technical solution to solve the above problems.

[0007] The preparation method of the graphene conductive cloth black shielding film with corrosion resistance function comprises a conductive cloth substrate, a composite metal plating layer deposited on the surface of the conductive cloth substrate, a two-way adjusting layer coated on the surface of the composite metal plating layer, a graphene outer layer immersed on the surface of the two-way adjusting layer, a self-repairing coating coated on the surface of the graphene outer layer, and a super-hydrophobic coating sprayed on the surface of the self-repairing coating, and comprises the following steps: Step 1, conductive cloth substrate pretreatment, immerse the conductive cloth substrate in a hydrochloric acid solution with a mass fraction of 4%-8% for 35-45 minutes, then wash it with deionized water until it is neutral, dry it, and then introduce active groups on the surface of the substrate; Step 2, deposit a composite metal plating layer, use electrochemical plating process to deposit a 5-8 μm thick nickel layer and a 2-3 μm thick copper layer on the surface of the conductive cloth substrate pretreated in step 1, forming a composite metal plating layer with a double-layer combination of nickel and copper; Step 3, intermediate layer coating, mix modified bentonite, potassium titanate whiskers, and polyurethane resin to prepare an adjusting agent, and coat the two-way adjusting layer on the surface of the conductive cloth substrate with the composite metal plating layer; Step 4, graphene surface modification, disperse graphene in a sodium dodecyl sulfate solution, add lanthanum sulfate and carboxymethyl cellulose to form a negatively charged graphene adjusting solution, and then introduce nano-hydroxyapatite to enhance the interface synergistic effect, and obtain a modified graphene layer; Step 5, graphene coating treatment, attach the modified graphene to the surface coated with the two-way adjusting layer by immersion coating to form a 0.5-1 μm thick graphene outer layer; Step 6, self-repairing coating coating: disperse urea-formaldehyde resin microcapsules loaded with benzotriazole or 2-mercaptobenzothiazole in water-based acrylic resin, and coat them on the surface of the graphene outer layer to form a 5-8 μm thick self-repairing coating, so that the whole forms a shielding film preliminary product; Step 7, super-hydrophobic surface treatment, mix polytetrafluoroethylene emulsion and nano-silicon dioxide, add perfluorooctyltrimethoxysilane as a hydrophobic modifier, and use spray pyrolysis technology to deposit a 1-2 μm thick super-hydrophobic coating on the surface of the shielding film preliminary product, with a water contact angle ≥150°; Step 8, pore sealing treatment, after the super-hydrophobic surface treatment in step 7, use a 5% concentration, pH=4-5 methyltrimethoxysilane hydrolysis solution for immersion treatment to seal the inter-fiber pores and enhance the surface hydrophobicity, and obtain a graphene conductive cloth black shielding film product with corrosion resistance function.

[0008] Preferably, the preparation method of the two-way adjusting layer in step 3 comprises: Step 3.1, immerse bentonite with a mass fraction of 3.5% in yttrium nitrate solution for infiltration treatment, dry it, and then mix it with potassium titanate whiskers with a particle size of 75 mesh to prepare a bentonite adjusting agent; Step 3.2, adding silane coupling agent and organic alcohol amine to carry out multi-stage blending treatment to form whisker modifier; Step 3.3, mixing the whisker modifier with bentonite modifier and polyurethane resin to obtain the adjusted bidirectional glue liquid as the bidirectional adjustment layer.

[0009] Preferably, the urea-formaldehyde resin microcapsules in step 6 are prepared by dissolving benzotriazole or 2-mercaptobenzothiazole in an organic solvent, adding urea-formaldehyde resin monomers, and then in-situ polymerization to prepare the urea-formaldehyde resin microcapsules; the microcapsules break when the coating scratch depth is greater than or equal to 5 microns, releasing the corrosion inhibitor to form a protective film, forming a protective film on the metal surface to inhibit corrosion expansion.

[0010] Preferably, the spray pyrolysis process parameters of the super-hydrophobic coating in step 7 are: nozzle temperature 150 DEG C, substrate temperature 80 DEG C, coating thickness 1-2 microns, water contact angle greater than or equal to 150 DEG, and rolling angle less than 5 DEG.

[0011] Preferably, the parameters of the pore sealing treatment in step 8 are: MTMS hydrolysis liquid concentration 5%, pH=4-5, immersion time 10-15 minutes, and liquid permeability of the treated material less than or equal to 1 microliter / cm square·min.

[0012] Preferably, the conductive cloth substrate is a nickel / copper plated fiber cloth, the thickness of the nickel plating layer is 5-8 microns, the thickness of the copper plating layer is 2-3 microns, and the surface resistivity of the conductive cloth is less than or equal to 0.1 ohm / sq.

[0013] Compared with the prior art, the beneficial effects of the present application are: Through the synergistic effect of hydrochloric acid pretreatment, adjustment of bidirectional glue liquid and amination of graphene, the adhesion of graphene to the substrate is significantly improved, solving the problem of interlayer peeling of traditional materials; it is beneficial to the protection of metal plating layer, forming a sandwich structure combined with a self-repairing corrosion-resistant coating, forming a triple protection of "metal barrier plus graphene shielding plus corrosion inhibitor release", reducing the corrosion rate of the plating layer by more than 90%; the combination of super-hydrophobic anti-permeation treatment and pore sealing treatment realizes the dual effect of super-hydrophobicity with a contact angle greater than or equal to 150 DEG and anti-permeation, and the service life in a salt spray environment is extended by several times or more.

[0014] Additional aspects and advantages of the application will be in part apparent and in part pointed out hereinafter in the description. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only only some embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without creative work based on the embodiments in the present application shall fall within the protection scope of the present application.

[0016] Figure 1 is a structural schematic diagram of a graphene conductive cloth black shielding film of the present application. Figure 2 is a process flow chart of the present application.

[0017] The reference signs and names in the drawings are as follows: Conductive cloth substrate 10, composite metal plating layer 20, bidirectional adjustment layer 30, graphene outer layer 40, self-repairing coating 50, super-hydrophobic coating 60. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present application.

[0019]

Embodiment 1

[0020]

Example 2

Example 3

[0021] In summary, the above three examples all include the preparation method of conductive cloth substrate 10 pretreatment, composite metal plating layer 20 deposition, bidirectional adjusting layer 30 coating, graphene surface modification and coating, self-repairing coating 50 coating, super-hydrophobic surface treatment and pore sealing treatment; in terms of conductive cloth substrate 10, nickel-plated or copper fiber cloth meeting the preferred parameters is selected; the bidirectional adjusting layer 30 is prepared by using the preferred modified bentonite and potassium titanate whisker composite system and specific blending steps; the self-repairing coating 50 is prepared by using the preferred in-situ polymerization method to prepare urea-formaldehyde resin microcapsules; the super-hydrophobic surface treatment strictly implements the preferred spray pyrolysis process parameters; the pore sealing treatment also uses the preferred MTMS hydrolysis solution concentration, pH value and immersion time; from the performance, the shielding film prepared in each example can have no obvious corrosion in a 5% NaCl solution continuous spray for 1000 hours in a salt spray test, and the performance is significantly improved compared with traditional products; electrochemical test shows that the charge transfer resistance is greatly improved, and the corrosion current density is reduced by more than 83%; flexibility test shows that it can bear repeated bending with radius 5 mm for 100,000 times and the shielding efficiency retention rate is >95%, and the graphene layer has no peeling off; therefore, the preparation method realizes excellent corrosion resistance, conductivity and mechanical properties of the shielding film through the synergistic effect of each link.

[0022] It is apparent for a person skilled in the art that the present application is not limited to the details of the above described exemplary embodiments, but that it can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the application being defined by the appended claims rather than the above description, and all changes coming within the meaning and equivalency range of the claims are intended to be embraced therein.

Claims

1. A method for preparing a graphene conductive cloth black shielding film with anti-corrosion function, characterized in that, The application relates to a graphene conductive cloth black shielding film, which comprises a conductive cloth substrate (10), a composite metal plating layer (20) deposited on the surface of the conductive cloth substrate (10), a bidirectional adjusting layer (30) coated on the surface of the composite metal plating layer (20), a graphene outer layer (40) immersed on the surface of the bidirectional adjusting layer (30), a self-repairing coating (50) coated on the surface of the graphene outer layer (40), and a super-hydrophobic coating (60) sprayed on the surface of the self-repairing coating (50). Step 1: the conductive cloth substrate (10) is pretreated, the conductive cloth substrate (10) is immersed in a hydrochloric acid solution with a mass fraction of 4%-8% for 35-45 minutes, then the conductive cloth substrate (10) is washed with deionized water until neutral, and the substrate surface is dried to introduce active groups; Step 2: the composite metal plating layer (20) is deposited, an electrochemical plating process is adopted to sequentially deposit a 5-8-micron-thick nickel layer and a 2-3-micron-thick copper layer on the surface of the conductive cloth substrate (10) pretreated in step 1, so as to form a composite metal plating layer (20) combined by the nickel and copper double layers; Step 3: the intermediate layer is coated, modified bentonite, potassium titanate whiskers and polyurethane resin are mixed to prepare an adjusting agent, and the bidirectional adjusting layer (30) is coated on the surface of the conductive cloth substrate (10) provided with the composite metal plating layer (20); Step 4: the graphene surface is modified, the graphene is dispersed in a sodium dodecyl sulfate solution, lanthanum sulfate and carboxymethyl cellulose are added to form a graphene adjusting liquid with negative charges, and nano-hydroxyapatite is introduced to enhance the interface synergistic effect, so as to obtain a modified graphene layer; Step 5: the graphene is coated, the modified graphene is attached to the surface coated with the bidirectional adjusting layer (30) in a manner of immersion coating, so as to form a 0.5-1-micron-thick graphene outer layer (40); Step 6: the self-repairing coating (50) is coated, urea-formaldehyde resin microcapsules loaded with benzotriazole or 2-mercaptobenzothiazole are dispersed in water-based acrylic resin, and the self-repairing coating (50) with a thickness of 5-8 microns is coated on the surface of the graphene outer layer (40), so that the whole forms a shielding film preliminary product; Step 7: the super-hydrophobic surface is treated, polytetrafluoroethylene emulsion and nano-silicon dioxide are mixed, perfluorooctyltrimethoxysilane is added as a hydrophobic modifier, and a 1-2-micron-thick super-hydrophobic coating (60) is deposited on the surface of the shielding film preliminary product by using a spray pyrolysis technology, and the water contact angle of the super-hydrophobic coating (60) is greater than or equal to 150 degrees; Step 8: the pore sealing treatment is performed, after the super-hydrophobic surface treatment in step 7, a hydrolysis solution of methyltrimethoxysilane with a concentration of 5% and a pH value of 4-5 is used for immersion treatment, so as to seal the pores between fibers and enhance the surface hydrophobicity, and finally a graphene conductive cloth black shielding film product with an anti-corrosion function is prepared.

2. The method of claim 1, wherein the graphene conductive cloth black shielding film having an anti-corrosion function is prepared by the steps of: coating a graphene conductive cloth with a graphene solution; drying the graphene conductive cloth; and coating the graphene conductive cloth with a black shielding film solution. The preparation method of the bidirectional adjusting layer (30) in step 3 comprises the following steps: Step 3.1: bentonite with a mass fraction of 3.5% is soaked in a yttrium nitrate solution for infiltration treatment, and then is mixed with potassium titanate whiskers with a particle size of 75 mesh to prepare a bentonite adjusting agent; Step 3.2: a silane coupling agent and an organic alcohol amine are added for multistage adjusting treatment to form a whisker modifier. Step 3.3, whiskers modifier mixed with bentonite modifier, polyurethane resin, to adjust the two-way glue liquid as two-way adjustment layer (30).

3. The method of claim 1, wherein the graphene conductive cloth black shielding film having an anti-corrosion function is prepared by the steps of: preparing a graphene conductive cloth black shielding film; and coating the graphene conductive cloth black shielding film with a coating solution containing a corrosion inhibitor. The urea-formaldehyde resin microcapsules of step 6 are prepared by dissolving benzotriazole or 2-mercaptobenzothiazole in an organic solvent and adding urea-formaldehyde resin monomers for in-situ polymerization; the microcapsules rupture when the coating scratch depth is ≥5 μm, releasing corrosion inhibitors to form a protective film, forming a protective film on the metal surface to inhibit corrosion propagation.

4. The method of claim 1, wherein the graphene conductive cloth black shielding film having an anti-corrosion function is prepared by the steps of: preparing a graphene conductive cloth black shielding film; and coating the graphene conductive cloth black shielding film with a coating solution containing a corrosion inhibitor. The spray pyrolysis process parameters of the super-hydrophobic coating (60) in step 7 are: nozzle temperature 150℃, substrate temperature 80℃, coating thickness 1-2 μm, water contact angle ≥150°, and rolling angle <5°.

5. The method of claim 1, wherein the graphene conductive cloth black shielding film having an anti-corrosion function is prepared by the steps of: preparing a graphene conductive cloth black shielding film; and coating the graphene conductive cloth black shielding film with a coating solution containing a corrosion inhibitor. The parameters for the pore sealing treatment in step 8 are: MTMS hydrolysis liquid concentration 5%, pH=4-5, immersion time 10-15 minutes, and the liquid permeability of the treated material ≤1 μL / cm²・min.

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