A method for preparing a modified reduced graphene oxide / polyaniline / silicone resin composite coating

Abstract

This invention, belonging to the field of protective materials, discloses a method for preparing a modified reduced graphene oxide / polyaniline / organic silicone resin composite coating. The coating is primarily composed of modified reduced graphene oxide, polyaniline, and an organosilicone resin matrix. By synergistically applying modified graphene (MGP) and polyaniline (PANI) materials, and leveraging the strong bonding interaction between the two heterogeneous interfaces, the composite coating exhibits excellent mechanical properties and electromagnetic shielding effectiveness. Furthermore, the preparation method is simple to operate and can be applied over large areas. The resulting coating has a smooth and evenly distributed surface, making it suitable for large-scale application.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of protective materials, and relates to a preparation method of a modified reduced graphene oxide / polyaniline / silicone resin composite coating. BACKGROUND

[0002] The shielding of electromagnetic field mainly utilizes the reflection, absorption and multiple reflection effects of a shielding body on electromagnetic waves to weaken the electromagnetic field. Polyaniline (PANI) is a conductive polymer compound and has special electrical and optical properties. The electrical activity of polyaniline is derived from the P electron conjugated structure in the molecular chain: with the expansion of the P electron system in the molecular chain, the P bonding state and the P* antibonding state form the valence band and the conduction band respectively, and this non-local P electron conjugated structure can form P-type and N-type conductive states through doping. After certain treatment, various devices and materials with special functions can be prepared, such as anti-static and electromagnetic shielding materials, but polyaniline has the shortcomings of insufficient mechanical strength and the like.

[0003] Graphene is a new type of carbon material and has the characteristics of high electrical conductivity, large dielectric constant, large dielectric loss of electromagnetic energy and the like. In addition, the elastic modulus of graphene can reach 1100 GPa, the breaking strength can reach 130 GPa, and graphene has excellent mechanical properties. More importantly, graphene is easy to be compounded with other materials and has high processability.

[0004] The invention patent with the patent number CN114292590A discloses a graphene oxide modified silicone resin coating and a preparation method and application thereof. The present application is different from the invention patent in the selection of materials, the preparation method and the application technical field of the composite coating material. The present application uses modified reduced graphene oxide and polyaniline in cooperation, and uses silicone resin as a bonding agent, and is mainly used for electromagnetic shielding material application.

[0005] The invention patent with the patent number CN101987908A discloses a preparation method of a graphene-epoxy resin composite material. The present application is different from the invention patent in the selection of materials, the preparation method and the application technical field of the composite coating material. The present application uses modified reduced graphene oxide and polyaniline in cooperation, and uses silicone resin as a bonding agent, and is mainly used for electromagnetic shielding material application. SUMMARY

[0006] The modified graphene MGP is applied in cooperation with the polyaniline PANI material, on one hand, there is a strong bonding effect between the effective MGP / PANI heterojunction, which improves the mechanical properties of the PANI material, on the other hand, the heterostructure increases the multiple reflection effect of electromagnetic waves, so that the MGP / PANI composite coating has more excellent electromagnetic shielding performance, and in addition, the silicone resin with good heat resistance and corrosion resistance is used as the binder, and finally through the complementary advantages of different materials, an electromagnetic shielding coating material with excellent electromagnetic shielding performance and mechanical strength is obtained.

[0007] A modified reduced graphene oxide / polyaniline / silicone resin composite coating, and a preparation method thereof.

[0008] A preparation method of a modified reduced graphene oxide / polyaniline / silicone resin composite coating, which is carried out according to the following steps:

[0009] High-quality reduced graphene oxide is prepared, and the used reduced graphene oxide is required to be composed of graphene sheets in micron scale and to be capable of achieving sufficient exfoliation of the sheets.

[0010] Under the condition of N2 protection, metal Li is added to the amine organic molecule in a certain proportion, and is fully stirred at room temperature to form a light yellow solution; the prepared reduced graphene oxide is added to the above solution, and is fully stirred at 30-50 DEG C for 12-24 h to obtain a black suspension, which is then centrifuged and washed with ethanol and deionized water for 3-5 times to obtain a black solid, which is then dispersed in deionized water and freeze-dried to obtain the modified reduced graphene oxide, and the freezing temperature is-40 to-60 DEG C.

[0011] The modified reduced graphene oxide powder and the polyaniline are added to a beaker in a certain mass fraction, and are ultrasonically dispersed, the ultrasonic frequency is 53 KHz, the tank temperature is room temperature, and the dispersion time is 10-20 min; the silicone resin is poured into the dispersed beaker, and a stirrer and a metal stirring paddle are used to stir and disperse the paint, the stirring rate is 800±50 rpm / min, and the stirring time is 4 h.

[0012] The curing agent is added before coating, and is stirred with a glass rod for not less than 5 min. The amount of the curing agent is 1-10 g (allowable deviation ± 1.0 g) per 100 g of the resin, the paint with the added curing agent should be used up within 2 h, and the coated substrate is a metal plate with a clean surface.

[0013] Preferably, in step two, the amine organic molecule is one of ethylenediamine and diethylenetriamine.

[0014] Preferably, in step two, the mass ratio of Li to the amine organic molecule is 1:1.5-2.5.

[0015] Preferably, in step two, the mass ratio of the added reduced graphene oxide to the solution obtained in step two is 1mg:1mL.

[0016] Preferably, in step three, the modified reduced graphene oxide powder and polyaniline are added into the beaker according to a certain mass fraction, and the mass ratio of the modified reduced graphene oxide to polyaniline is 1:(2-4).

[0017] Preferably, in step three, the mass ratio of the modified reduced graphene oxide powder and polyaniline to the silicone resin is 1:(9-50).

[0018] Preferably, in step four, the curing agent is an isocyanate curing agent.

[0019] Preferably, in step four, the coating process is brushing or rolling.

[0020] Preferably, in step four, the metal plate is one of a clean-surfaced aluminum alloy, a magnesium alloy, or a steel plate.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The present application provides a preparation method of an electromagnetic shielding modified graphene composite coating, which has a simple preparation process and flow, high hardness and modulus, and excellent electromagnetic shielding performance.

[0023] The above beneficial effects will be described below in combination with specific examples. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a microstructure diagram of high-quality reduced graphene oxide;

[0025] Figure 2 is a modified reduced graphene oxide / polyaniline / silicone resin composite coating. DETAILED DESCRIPTION

[0026] In order to better understand the content of the present application, the present application will be further described below in combination with specific implementation examples. The following examples are implemented based on the technology of the present application, combined with detailed implementation modes and operation steps, but the protection scope of the present application is not limited to the following examples. Unless otherwise specified, the experimental methods used in the present application are conventional methods, and the experimental apparatus, materials, reagents, etc. used can be obtained from commercial channels. Example 1

[0027] (1) Weigh 80 mg of high-quality reduced graphene oxide and observe its microstructure to check whether its microscopic layer structure is completely peeled off, that is, the number of graphene layer stacking layers. After observation, the reduced graphene oxide used in this study was peeled off into one or more layers (2-4 layers), the layer outline is clearly visible, and the layer diameter is about 20-30 μm ( Figure 1 ), indicating that the graphene meets subsequent needs.

[0028] (2) Under N2 protection, 50 mg of metallic Li was added to 80 mL of diethylenetriamine and stirred thoroughly at room temperature until it turned light yellow to form a solution; 80 mg of reduced graphene oxide was added to the above solution and stirred thoroughly at 30-50 °C for 12-24 h to obtain a black suspension, which was then centrifuged and washed 3-5 times with ethanol and deionized water to obtain graphene solid. The black solid was then dispersed in deionized water and freeze-dried to obtain the modified reduced graphene oxide at a freezing temperature of -50 °C;

[0029] (3) Weigh 1.5 g of modified reduced graphene oxide powder and 3 g of polyaniline into a beaker and perform ultrasonic dispersion. The ultrasonic frequency is 53 kHz, the temperature in the tank is room temperature, and the dispersion time is 10 min. Pour 50 g of methylphenyl polysiloxane resin into the dispersed beaker and use a stirrer and a metal stirring paddle to stir and disperse the paint. The stirring rate is 800 ± 50 rpm / min and the stirring time is 4 h.

[0030] (4) Before coating, 4g of isocyanate curing agent was added and stirred with a glass rod for 10 minutes. The prepared modified graphene composite material was then prepared into a coating film using the paint film scraping method in GB / T 1727-1992. The coating substrate was 1060Al and the film thickness was 200μm. After curing in a blast drying oven at a temperature of 120℃ for 30 minutes, a coating sample with a smooth surface and uniform distribution was obtained ( Figure 2 ).

[0031] (5) The hardness and modulus of the prepared coating were measured. The results showed that the modulus of the coating prepared by the present invention was 4.82 GPa and the hardness was 195 MPa. The prepared composite coating had good mechanical strength. The electromagnetic shielding effect test of the composite coating showed that in the X-band, the electromagnetic shielding test effect reached 32.3 dB, which showed excellent electromagnetic shielding effectiveness.

[0032] The above description is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a modified reduced graphene oxide / polyaniline / silicone resin composite coating, characterized in that: Follow these steps: (1) Prepare high-quality reduced graphene oxide, which is required to be composed of graphene sheets at the micron level and be able to fully exfoliate the sheets; (2) Under the protection of N2, metallic Li is added to the amine organic molecule at a mass ratio of 1:1.5-2.5, and the solution is formed by stirring at room temperature until it turns light yellow; the prepared reduced graphene oxide is added to the above solution, and the mass ratio of the added reduced graphene oxide to the light yellow solution is 1 mg:1 mL, and the solution is stirred at 30-50 ° C for 12-24 h to obtain a black suspension, which is then centrifuged and washed 3-5 times with ethanol and deionized water to obtain a black solid, which is then dispersed in deionized water and freeze-dried to obtain modified reduced graphene oxide, and the freezing temperature is -40 to -60 ° C; (3) Add the modified reduced graphene oxide powder and polyaniline in a mass ratio of 1:(2-4) into a beaker and perform ultrasonic dispersion. The ultrasonic frequency is 53KHz, the temperature in the tank is room temperature, and the dispersion time is 10-20min. Pour the silicone resin into the dispersed beaker. The mass ratio of the modified reduced graphene oxide powder and polyaniline to the silicone resin is 1:(9-50). Use a stirrer and a metal stirring paddle to stir and disperse the paint. The stirring rate is 800±50rpm / min and the stirring time is 4h. (4) Add isocyanate curing agent before coating and stir with a glass rod for no less than 5 minutes. The amount of curing agent is 1-10g for every 100g of resin. The paint with isocyanate curing agent should be used up within 2 hours. The coated substrate is a metal plate with a clean surface.

2. The method for preparing the modified reduced graphene oxide / polyaniline / silicone resin composite coating according to claim 1, characterized in that ,The coating process in step (4) is brush coating or roller coating.

3. The method for preparing the modified reduced graphene oxide / polyaniline / silicone resin composite coating according to claim 1, characterized in that ,The metal plate described in step (4) is one of aluminum alloy plate, magnesium alloy plate or steel plate.

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