GRAPHENE ANTI-CORROSION COATING

Abstract

A graphene anti-corrosion coating is described that comprises an epoxy resin and graphene subjected to surface modification, where the addition amount of the graphene is 0.01-0.2 wt % of the total mass of coating solid. By performing surface treatment on the graphene, the dispersity of the graphene in the coating is improved, and the compactness of the coating is enhanced.

Claims

1. A graphene anti-corrosion coating, comprising an epoxy resin and graphene, wherein the graphene is modified by a surface treating agent, and the addition amount of the graphene is 0.01-0.2 wt % of the total mass of coating solid.

2. The graphene anti-corrosion coating according to claim 1, wherein the addition amount of the graphene is 0.01-0.05 wt % of the total mass of the coating solid.

3. The graphene anti-corrosion coating according to claim 1, wherein an atomic ratio of oxygen element to carbon element (O/C ratio) in the graphene is 0.05-0.40.

4. The graphene anti-corrosion coating according to claim 1, wherein an atomic ratio of nitrogen element to carbon element (N/C ratio) in the graphene is 0.01-0.05.

5. The graphene anti-corrosion coating according to claim 1, wherein the thickness of the graphene is 2-12 nm.

6. The graphene anti-corrosion coating according to claim 1, wherein the surface treating agent is one or more of arylaminos, pyrazolones, and catechols.

7. The graphene anti-corrosion coating according to claim 1, wherein the surface treating agent is one or more selected from the group consisting of o-chloroaniline, p-chloroaniline, o-toluidine, acetanilide, 2-aminobenzylamine, p-methoxyaniline, 2-nitroaniline, 2-phenylethylamine hydrochloride, 4,4′-diaminodiphenylmethane, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone, bispyrazolone, picric acid, 1-phenyl-3-methyl-5-pyrazolone, catechol borane, pyrocatechol violet, 3,5-di-tert-butyl-1,2-benzenediol, 4-nitrocatechol, and dopamine hydrochloride.

8. The graphene anti-corrosion coating according to claim 1, wherein the surface treating agent is one or more selected from the group consisting of 2-aminobenzylamine, 2-phenethylamine hydrochloride, 4,4′-diaminodiphenylmethane, bispyrazolone, and dopamine hydrochloride.

9. The graphene anti-corrosion coating according to claim 1, wherein the glossiness of a paint film of the coating is 3 or less.

10. The graphene anti-corrosion coating according to claim 1, wherein the oxygen transmission rate of the paint film of the coating is 0.35 g/m.sup.2.Math.h or less.

Description

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0038] The present invention will be further described by the following Embodiments, but these embodiments are only for illustration and are not intended to define the scope of the present invention.

[0039] 1. Raw Materials

[0040] (1) Epoxy Resin

[0041] One or more of epoxy resins E-51, E-44, E-20, E-12, E-06 is/are used as a substrate of a coating.

[0042] (2) Modified Graphene

[0043] In the present invention, the method of preparing graphene may be as described below, but is not limited thereto. The modified graphene used in the present invention can be obtained by surface treatment of graphene obtained by a chemical reduction method. The commonly used graphene is mainly divided into three categories: CVD graphene, physically exfoliated graphene, and chemically exfoliated graphene. The CVD graphene may be made into a single layer, but there are no functional groups on the surface. Therefore, it is difficult to perform surface treatment, resulting in poor dispersity. Meanwhile, the CVD graphene is not suitable for large-scale applications because of high cost. The physically exfoliated graphene is simple in preparation method, but is difficult to be thin, and has the properties close to natural graphite. The surface of chemically exfoliated graphene contains functional groups, may be subjected to surface treatment as required, and may also be made to be very thin. Therefore, the chemically exfoliated graphene is selected in this experiment. Graphite oxide as a raw material is self-made from natural graphite by Hummers method. The natural graphite was purchased from Qingdao Haida Graphite Co., Ltd., and the model is LC-180. The thickness of graphite oxide is finely adjusted by controlling the addition amount of an oxidant during the oxidation process; and the diameter and size distribution of the graphite oxide are adjusted by the micronization treatment at the later stage of the reaction. The micronization processing here refers to ultrasounds and various processing methods with micronization processing functions. The resulting graphite oxide is treated with a surface treating agent, and the surface treatment is carried out at normal temperature and normal pressure. After 3 hours of reaction, modified graphite oxide is obtained. A reducing agent is used to reduce the modified graphite oxide to obtain modified graphene (slurry, a concentration of 2%), the reduction is carried out at normal temperature and pressure, and the reaction time is 1.5 hours.

[0044] Different surface treating agents and reducing agents are used to obtain modified graphene with different parameters, and the performances are shown in Table 1 below. D50/D90 is measured by a volume reference mode of particle size distribution test, the thickness is measured by an atomic force microscope (AFM), and an O/C ratio and a N/C ratio are measured by X-ray photoelectron spectroscopy (XPS).

TABLE-US-00001 TABLE 1 List of modified graphene (slurry, a concentration of 2%) Size D50 Thickness D90/ O/C N/C Reducing No. (μm) (nm) D50 ratio ratio Surface treating agent agent 1 5 5 1.3 0.1 0.015 Dipyrazolone Hydrazine hydrate 2 20 10 1.1 0.1 0.015 2-phenylethylamine Hydroiodic hydrochloride acid vapor 3 10 3 1.4 0.1 0.015 4,4'-Diaminodiphenylmethane Sodium dithionite 4 30 12 1.5 0.1 0.015 Dopamine Thermal hydrochloride reduction 5 15 9 1.3 0.1 0.015 Bis (3-methyl-1-phenyl-5- Sodium pyrazolone) dithionite 6 1 3 1.3 0.1 0.015 3-(2,3- Sodium Glyoxypropoxy)propyltrimethoxy dithionite silane (KH-560) 7 1 3 1.3 0.1 0.015 2-Aminobenzylamine Sodium dithionite 8 1 3 1.3 0.04 0.015 2-Aminobenzylamine Sodium dithionite 9 1 3 1.3 0.17 0.015 2-Aminobenzylamine Sodium dithionite 10 1 3 1.3 0.19 0.015 2-Aminobenzylamine Sodium dithionite 11 1 3 1.3 0.25 0.015 2-Aminobenzylamine Sodium dithionite 12 1 3 1.3 0.4 0.015 2-Aminobenzylamine Sodium dithionite 13 1 3 1.3 0.5 0.015 2-Aminobenzylamine Sodium dithionite 14 1 3 1.3 0.1 0.005 2-Aminobenzylamine Sodium dithionite 15 1 3 1.3 0.1 0.01 2-Aminobenzylamine Sodium dithionite 16 1 3 1.3 0.1 0.03 2-Aminobenzylamine Sodium dithionite 17 1 3 1.3 0.1 0.05 2-Aminobenzylamine Sodium dithionite 18 1 3 1.3 0.1 0.07 2-Aminobenzylamine Sodium dithionite 19 1 3 1.3 0.1 0.16 2-Aminobenzylamine Sodium dithionite 20 1 1.5 1.3 0.1 0.015 2-Aminobenzylamine Sodium dithionite 21 1 2 1.3 0.1 0.015 2-Aminobenzylamine Sodium dithionite 22 1 5 1.3 0.1 0.015 2-Aminobenzylamine Sodium dithionite 23 1 10 1.3 0.1 0.015 2-Aminobenzylamine Sodium dithionite 24 1 12 1.3 0.1 0.015 2-Aminobenzylamine Sodium dithionite 25 1 15 1.3 0.1 0.015 2-Aminobenzylamine Sodium dithionite

[0045] 2-Aminobenzylamine: Sinopharm Chemical Reagent Co., Ltd., used directly.

[0046] Bispyrazolone: Sinopharm Chemical Reagent Co., Ltd., used directly.

[0047] Dopamine hydrochloride: Sinopharm Chemical Reagent Co., Ltd., used directly.

[0048] 2-phenylethylamine hydrochloride: Sinopharm Chemical Reagent Co., Ltd., used directly.

[0049] 4,4′-Diaminodiphenylmethane: Shanghai Aladdin Reagent Co., Ltd., used directly.

[0050] Bis(3-methyl-1-phenyl-5-pyrazolone): Shanghai Aladdin Reagent Co., Ltd., used directly.

[0051] 3-(2,3-Glyoxypropoxy)propyltrimethoxysilane (KH-560): Shanghai Aladdin Reagent Co., Ltd., used directly.

[0052] (3) Reducing Agent

[0053] Sodium dithionite: Sinopharm Chemical Reagent Co., Ltd., used directly.

[0054] Hydrazine hydrate: Sinopharm Chemical Reagent Co., Ltd., used directly.

[0055] Hydroiodic acid: Sinopharm Chemical Reagent Co., Ltd., used directly.

[0056] (4) Other additives: bentonite, barite, iron oxide red, zinc powder, Sinopharm Chemical Reagent Co., Ltd., used directly; a dispersant (silicate dispersant: DISPERBYK-103), a defoamer (organosilicone defoamer: BYK-015), a wetting agent (polyester modified organosilicone wetting agent: DISPERBYK-142), an anti-flash rust agent (organic zinc chelate anti-flash rust agent: FA-179), all purchased from Kunshan Daiquan Fine Chemical & Technology Co., Ltd., used directly.

[0057] 2. Measuring Methods of Related Properties in the Embodiments and Comparative Examples of the Present Invention are as Follows:

[0058] A. Content of graphene in a graphene anti-corrosion coating: calculated by the following formula:

[00001]$\begin{array}{c}\mathrm{content}\mathrm{of}\mathrm{graphene}\\ \mathrm{in}\mathrm{coating}\end{array}=\frac{\mathrm{addition}\mathrm{amount}\mathrm{of}\mathrm{graphene}\mathrm{in}\mathrm{coating}}{\mathrm{total}\mathrm{mass}\mathrm{of}\mathrm{coating}\mathrm{solid}}\times 100\%$

[0059] B. Thickness of a graphene coating layer: paint film thickness gauge (TIME TT220, China)

[0060] Test method: after the thickness gauge is reset to zero, a dried paint film sample is put under a probe of an instrument for measurement. Different areas on the paint film sample are selected to be measured for 10 times, and an average value is then taken.

[0061] C. Bond energy binding: infrared spectrum analysis (SHIMADZU AIM-9000, Japan)

[0062] Test method: a Fourier transform infrared spectrometer is used to test the dried coating, and whether functional groups and chemical bonds appear or disappear are determined according to characteristic absorption peaks in an infrared spectrum.

[0063] D. Flexibility: bending tester (LEPU FA-YZQ-II, China)

[0064] Test method: the coating is applied on a steel plate; after a paint film is dried, the bending tester is opened completely, shaft rods of different diameters are selected and inserted into a sample plate, so that the coating faces a seat plate. The instrument is closed at a steady speed within 1-2 s, and a test plate is bent by 1800 around the axis. The flexibility of the paint film is expressed by the smallest shaft rod diameter that does not cause the paint film to crack.

[0065] E. Impact resistance: impact tester (DALAI QCJ-120, China)

[0066] Test method: the dried paint film is placed under the impact tester, a heavy hammer drops with a fixed mass on the test board, and the impact resistance of the paint film is expressed by the maximum height that does not cause damage to the paint film.

[0067] F. Resistivity: Resistivity tester (DESCO EMI19787, USA)

[0068] Test method: the coating is applied onto an insulator material (such as PET), and after the coating is dried into a paint film, the surface resistance of the coating is tested by the resistivity tester.

[0069] G. Glossiness: glossiness meter (SPEEDRE SDR600, China)

[0070] Test method: the glossiness of the coating is measured based on the surface reflection of light relative to a polished glass reference standard. The amount of light reflected on the surface depends on the angle of incidence and the properties of the surface. The glossiness is classified as matte, semi-gloss or high gloss. In order to determine the most suitable measurement angle, the measurement starts with a glossiness meter set at an incident angle of 90°. If the test result is 10-70, the coating layer is called a “semi-gloss” coating layer and should be measured at an angle of 60°. If the test result is less than 10, the product is called a “low-gloss” product and should be measured at an angle of 85°. If the test result is larger than 70, the product is called a “high-gloss” product and should be measured at an angle of 20°.

[0071] H. Oxygen transmission rate: gas penetration tester (Labthink CLASSIC 216, China)

[0072] Test method: the coating is made into a film, and the gas permeability test is performed on the gas penetration tester by using a differential pressure method according to the JIS K7126-A standard. The coating film to be tested is fixed in the middle of a test chamber to divide the chamber into an upper chamber and a lower chamber with a constant pressure difference between them. Gas molecules will penetrate the sample from the high-pressure chamber into the low-pressure chamber, the change in pressure in the low-pressure chamber is then monitored, and the gas transmission rate is calculated by the system.

[0073] I. Salt spray resistance: neutral salt spray test box (HAIDA HD-E808-120, China)

[0074] Test method: the coating is applied to the steel plate that has been sandblasted, according to the national standard GB/T 1771-2007; and after the coating is dried, the surface is scratched and continuously tested in the neutral salt spray test box. The salt spray resistance of the coating is indicated by a time when the coating blisters and peels off, or the scratch or rust exceed 2 mm.

Embodiment 1

[0075] 13 g of curing agent is weighed, added with 20 g of water, 0.1 g of wetting agent and 0.2 g of dispersant, and then stirred;

[0076] after stirring for 20 minutes, 0.1 g of dispersant, 0.1 g of defoamer, and 0.3 g of bentonite are added to the system, and continuously stirred for 15 minutes;

[0077] 7 g of talcum powder is added, stirred for 5 minutes, added with 4 g of barite, 7 g of iron oxide red and 0.2 g of defoamer, and then stirred for 15 minutes.

[0078] 0.2 g of anti-flash rust agent is added, stirred and dispersed for 15 minutes.

[0079] 0.03 g of modified graphene is added and dispersed for 20 minutes;

[0080] 215.2 g of zinc powder and 40 g of water are added to ensure the wetting of the system;

[0081] 60 g of epoxy resin is added and dispersed for 15 minutes.

[0082] In order to ensure the dispersity, a homogenizer is used to disperse for 10 minutes to obtain a graphene anti-corrosion coating.

[0083] After the system is filtered with a 200-mesh filter screen, the finished coating is sprayed on a sandblasted steel plate, and various performances of the coating are then tested. The specific performances are shown in Table 2-1.

Comparative Example 1

[0084] Except that the modified graphene is not added, the same operations as in Embodiment 1 are performed to obtain the graphene anti-corrosion coating shown in Table 2-1.

Comparative Example 2

[0085] In addition to changing the modified graphene to graphene without surface treatment, the same operations as in Embodiment 1 are performed to obtain the graphene anti-corrosion coating shown in Table 2-1.

Embodiments 2-6, Comparative Examples 3-5

[0086] The content of the modified graphene of the coating in Embodiment 1 is changed as shown in Table 2-1 and Table 2-2, and the same operations as in Embodiment 1 are performed to obtain the graphene anti-corrosion coatings shown in Table 2-1 and Table 2-2.

Embodiments 7-24

[0087] Except that the content of the modified graphene in Embodiment 1 is changed as shown in Table 3-1, Table 3-2 and Table 3-3, the same operations as in Embodiment 1 are performed to obtain the graphene anti-corrosion coatings shown in Table 3-1, Table 3-2 and Table 3-3.

Embodiments 25-30

[0088] Except that the content of the modified graphene in Embodiment 1 is changed as shown in Table 4, the same operations as in Embodiment 1 are performed to obtain the graphene anti-corrosion coating shown in Table 4.

TABLE-US-00002 TABLE 2-1 Comparative Comparative Comparative Embodiment 1 example 1 example 2 example 3 Embodiment 2 Embodiment 3 Modified 7 None None 7 7 7 graphene (No.) Surface 2- / / / / 2- 2- 2- treating Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine agent O/C ratio 0.1 0.1 0.1 0.1 0.1 N/C ratio 0.015 0 0.015 0.015 0.015 Sheet 1 1 1 1 1 diameter D50 (μm) Thickness (nm) 3 3 3 3 3 Epoxy resin E-44 E-44 E-44 E-44 E-44 E-44 Addition 0.01 0 0.01 0.008 0.02 0.03 amount of graphene (wt %) Thickness of 60 60 60 60 60 60 paint film of coating (μm) Addition 70 70 70 70 70 70 amount of zinc powder (wt %) C-N bonding Yes No No Yes Yes Yes interaction Characteristic Yes No No Yes Yes Yes peaks appearing at 1000- 1300 cm.sup.−1 in infrared spectrum Toughness of 1 2 2 1 1 1 paint film (mm) Impact 75 50 55 65 75 75 resistance of paint film (kg .Math. cm) Resistivity 3 × 10.sup.6 1 × 10.sup.11 1 × 10.sup.10 1 × 10.sup.7 1 × 10.sup.6 7 × 10.sup.5 (Ωm) Glossiness 1.3 40 23 6.3 1.1 1 Oxygen 0.35 7.37 5.22 4.48 0.29 0.27 transmission rate (g/m.sup.2 .Math. h) Salt spray 2590 780 900 1320 2600 2650 resistance time (h)

TABLE-US-00003 TABLE 2-2 Comparative Comparative Embodiment 4 Embodiment 5 Embodiment 6 example 4 example 5 Modified graphene (No.) 7 7 7 7 7 Surface treating agent 2-Aminobenzylamine 2-Aminobenzylamine 2-Aminobenzylamine 2-Aminobenzylamine 2-Aminobenzylamine O/C ratio 0.1 0.1 0.1 0.1 0.1 N/C ratio 0.015 0.015 0 0.015 0.015 Sheet diameter D50 (μm) 1 1 1 1 1 Epoxy resin E-44 E-44 E-44 E-44 E-44 Thickness (nm) 3 3 3 3 3 Addition amount of graphene 0.05 0.1 0.2 0.5 1 (wt %) Thickness of paint film 60 60 60 60 60 of coating (μm) Addition amount of zinc 70 70 70 70 70 powder (wt %) C—N bonding interaction Yes Yes Yes Yes Yes Characteristic peaks Yes Yes Yes Yes Yes appearing at 1000-1300 cm.sup.−1 in infrared spectrum Toughness of paint film 1 1 1 1 2 (mm) Impact resistance of paint 75 70 70 50 40 film (kg .Math. cm) Resistivity (Ωm) 2 × 10.sup.5 1 × 10.sup.5 6 × 10.sup.4 2 × 10.sup.4 5 × 10.sup.3 Glossiness 0.5 4.3 6.6 18 27 Oxygen transmission rate 0.12 3.01 3.75 10.44 102.54 (g/m.sup.2 .Math. h) Salt spray resistance time 2960 1630 1460 660 100 (h)

[0089] As shown in Table 2-1 and Table 2-2, it can be seen in combination with Embodiments 1-6 and Comparative Examples 1-5 that within a certain range, the addition of the modified graphene can greatly improve the performances of the coating. If this range is exceeded, the graphene content is too high, such that the graphene is prone to agglomeration, which reduces the dispersity of the graphene in the coating. At this time, the agglomeration may cause local defects in the coating, so the large amount of graphene will reduce the performances of the coating. When modified graphene is added to the coating, the impact resistance and toughness are promoted, combination bonds are formed, the oxygen transmission rate and glossiness decrease, and the salt spray resistance time increases, that is, the overall performance is improved.

TABLE-US-00004 TABLE 3-1 Embodiment 7 Embodiment 8 Embodiment 9 Embodiment 10 Embodiment 11 Embodiment 12 Modified 8 9 10 11 12 13 graphene (No.) Surface 2- 2- 2- 2- 2- 2- treating Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine agent O/C ratio 0.04 0.11 0.19 0.25 0.4 0.5 N/C ratio 0.015 0.015 0.015 0.015 0.015 0.015 Sheet 1 1 1 1 1 1 diameter D50 (μm) Thickness (nm) 3 3 3 3 3 3 Epoxy resin E-44 E-44 E-44 E-44 E-44 E-44 Addition 0.01 0.01 0.01 0.01 0.01 0.01 amount of graphene (wt %) Thickness of 60 60 60 60 60 60 paint film of coating (μm) Addition 70 70 70 70 70 70 amount of zinc powder (wt %) C-N bonding Yes Yes Yes Yes Yes Yes interaction Characteristic Yes Yes Yes Yes Yes Yes peaks appearing at 1000- 1300 cm.sup.−1 in infrared spectrum Toughness of 1 1 1 1 1 1 paint film (mm) Impact 70 75 75 75 75 70 resistance of paint film (kg .Math. cm) Resistivity 1 × 10.sup.6 5 × 10.sup.6 7 × 10.sup.6 9 × 10.sup.6 1 × 10.sup.7 7 × 10.sup.7 (Ωm) Glossiness 2.9 0.5 0.7 0.9 1.1 2.9 Oxygen 1.18 0.15 0.21 0.23 0.27 1.26 transmission rate (g/m.sup.2 .Math. h) Salt spray 1900 2850 2780 2760 2660 1800 resistance time (h)

TABLE-US-00005 TABLE 3-2 Embodiment 13 Embodiment 14 Embodiment 15 Embodiment 16 Embodiment 17 Embodiment 18 Modified 14 15 16 17 18 19 graphene (No.) Surface 2- 2- 2- 2- 2- 2- treating Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine agent O/C ratio 0.1 0.1 0.1 0.1 0.1 0.1 N/C ratio 0.005 0.01 0.03 0.05 0.07 0.16 Sheet 1 1 1 1 1 1 diameter D50 (μm) Thickness (nm) 3 3 3 3 3 3 Epoxy resin E-44 E-44 E-44 E-44 E-44 E-44 Addition 0.01 0.01 0.01 0.01 0.01 0.01 amount of graphene (wt %) Thickness of 60 60 60 60 60 60 paint film of coating (μm) Addition 70 70 70 70 70 70 amount of zinc powder (wt %) C-N bonding Yes Yes Yes Yes Yes Yes interaction Characteristic Yes Yes Yes Yes Yes Yes peaks appearing at 1000- 1300 cm.sup.−1 in infrared spectrum Toughness of 1 1 1 1 1 1 paint film (mm) Impact 70 70 75 70 70 65 resistance of paint film (kg .Math. cm) Resistivity 8 × 10.sup.5 2 × 10.sup.6 6 × 10.sup.6 7 × 10.sup.6 9 × 10.sup.7 7 × 10.sup.8 (Ωm) Glossiness 2.9 2.1 0.6 1.7 3 5.4 Oxygen 1.25 0.89 0.18 0.77 1.93 3.81 transmission rate (g/m.sup.2 .Math. h) Salt spray 1820 2200 2810 2400 1560 1420 resistance time (h)

TABLE-US-00006 TABLE 3-3 Embodiment 19 Embodiment 20 Embodiment 21 Embodiment 22 Embodiment 23 Embodiment 24 Modified 20 21 22 23 24 25 graphene (No.) Surface 2- 2- 2- 2- 2- 2- treating Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine Aminobenzylamine agent O/C ratio 0.1 0.1 0.1 0.1 0.1 0.1 N/C ratio 0.015 0.015 0.015 0.015 0.015 0.015 Sheet 1 1 1 1 1 1 diameter D50 (μm) Thickness (nm) 1.5 2 5 10 12 15 Epoxy resin E-44 E-44 E-44 E-44 E-44 E-44 Addition 0.01 0.01 0.01 0.01 0.01 0.01 amount of graphene (wt %) Thickness of 60 60 60 60 60 60 paint film of coating (μm) Addition 70 70 70 70 70 70 amount of zinc powder (wt %) C-N bonding Yes Yes Yes Yes Yes Yes interaction Characteristic Yes Yes Yes Yes Yes Yes peaks appearing at 1000- 1300 cm.sup.−1 in infrared spectrum Toughness of 1 1 1 1 1 1 paint film (mm) Impact 70 75 75 75 75 70 resistance of paint film (kg .Math. cm) Resistivity 4 × 10.sup.5 7 × 10.sup.5 6 × 10.sup.6 8 × 10.sup.6 2 × 10.sup.7 3 × 10.sup.8 (Ωm) Glossiness 2.2 0.6 1.5 1.9 2.3 2.4 Oxygen 0.95 0.16 0.38 0.54 0.81 1.03 transmission rate (g/m.sup.2 .Math. h) Salt spray 2130 2830 2550 2470 2250 2080 resistance time (h)

[0090] As shown in Table 2-1, Table 2-2, Table 3-1, Table 3-2, and Table 3-3, in combination with Embodiments 1, 7-12, the lower the 0/C ratio within a certain range, the higher the conductivity of the modified graphene, and the higher the overall conductivity of the coating, which facilitates increasing the utilization rate of zinc powder and prolonging the anti-corrosion time. In combination with Embodiments 1, 13-18, it can be seen that within a certain range, the N/C ratio is high, which indicates that a grafting rate of the surface treating agent is relatively high, the dispersity of the graphene will be relatively better, and the overall performance of the graphene coating is also relatively good.

TABLE-US-00007 TABLE 4 Embodiment 25 Embodiment 26 Embodiment 27 Embodiment 28 Embodiment 29 Embodiment 30 Modified 1 2 3 4 5 6 graphene (No.) Surface Dipyrazolone 2- 4,4′- Dopamine Bis (3-methyl-1- 3-(2,3- treating phenylethylamine Diaminodiphenylme hydrochloride phenyl-5- Glyoxypropoxy) pro agent hydrochloride thane pyrazolone) pyltrimethoxysilane (KH-560) O/C ratio 0.1 0.1 0.1 0.1 0.1 0.1 N/C ratio 0.015 0 0.015 0.015 0.015 0 Sheet 5 20 10 30 15 1 diameter D50 (μm) Thickness (nm) 5 10 3 12 9 3 Epoxy resin E-44 E-20 E-51 E-12 E-06 E-51 Addition 0.01 0.01 0.01 0.01 0.01 0.01 amount of graphene (wt %) Thickness of 60 60 60 60 60 60 paint film of coating (μm) Addition 70 70 70 70 70 70 amount of zinc powder (wt %) C-N bonding Yes Yes Yes Yes Yes No interaction Characteristic Yes Yes Yes Yes Yes No peaks appearing at 1000- 1300 cm.sup.−1 in infrared spectrum Toughness of 1 1 1 1 1 1 paint film (mm) Impact 70 75 75 70 70 65 resistance of paint film (kg .Math. cm) Resistivity 3 × 10.sup.6 7 × 10.sup.6 8 × 10.sup.6 2 × 10.sup.7 9 × 10.sup.6 3 × 10.sup.8 (Ωm) Glossiness 2.4 2.1 1 2.3 2.7 4.2 Oxygen 0.84 0.74 0.24 0.8 1.06 3.21 transmission rate (g/m.sup.2 .Math. h) Salt spray 2300 2430 2700 2360 2050 1490 resistance time (h)

[0091] As shown in Table 2-1, Table 2-2 and Table 4, in combination with Embodiments 1, 25-30 and Comparative Example 2, arylaminos, pyrazolones, and catechols are used as the surface treating agents to treat graphene oxides with different physical parameters, and modified graphene obtained by reduction by means of different methods can improve the performances of the coating, and the improvement effect is more obvious than that of graphene without surface treatment.