Waterborne epoxy high-thermal-conductivity graphene coating as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of graphene coatings, and particularly relates to a waterborne epoxy high-thermal-conductivity graphene coating as well as a preparation method and application thereof. The coating comprises a component A and a component B, wherein the component A comprises the following components in percentage by mass: water-borne epoxy resin; a defoaming agent; a dispersant; titanium dioxide; graphene; a silane coupling agent; a special antirust filler; performing stone milling to obtain powder; compounding ferrotitanium powder; expansion microbeads; organic bentonite; a leveling agent; deionized water; and the component B is a water-free dilutable amine curing agent. According to the invention, the problem of dispersion stability in a system is solved, and the coating has excellent thermal conductivity, excellent corrosion resistance, good electrical conductivity and good physical and mechanical properties. The production cost is low, and the comprehensive performance is obviously improved. The coating can be used for surface coating of heat exchangers and solar protection plates, and provides excellent high-heat-conduction protection and excellent utilization rate of heat-conduction converted heat energy.

Description

Technical Field

[0001] This invention belongs to the field of graphene coating technology, specifically relating to a water-based epoxy high thermal conductivity graphene coating, its preparation method, and its application. Background Technology

[0002] Waterborne epoxy anticorrosion paints are favored by many users in anticorrosion engineering projects due to their outstanding anticorrosion performance, wide compatibility, and reasonable price. With the development of modern industry, the emergence of new industrial sectors, and the construction of many modern projects, higher demands are being placed on the environmental resistance and service life of waterborne epoxy resin anticorrosion coatings. Improving the long-term anticorrosion performance of waterborne epoxy anticorrosion paints is a key focus of their efforts.

[0003] Graphene, the world's thinnest anti-corrosion material, can be used for metal protection. It is currently the thinnest and strongest material in the world, with a thermal conductivity higher than carbon nanotubes and diamond. Its electron mobility at room temperature is also higher than that of carbon nanotubes or silicon crystals, and its resistivity is lower than that of copper or silver, making it the material with the lowest resistivity in the world. Research on graphene's applications in corrosion protection has attracted the attention of researchers worldwide. Numerous studies have shown that graphene's extremely large specific surface area, excellent barrier properties, high chemical stability, and good electrical conductivity significantly enhance the overall performance of anti-corrosion coatings. These properties include improved adhesion to the substrate, enhanced wear resistance and corrosion resistance, while also being environmentally friendly, safe, and free of secondary pollution.

[0004] Graphene's unique structural properties give it advantages in both physical and electrochemical corrosion protection. The layered, interlaced structure of graphene forms a labyrinthine shielding structure within the coating, effectively inhibiting the wetting, penetration, and diffusion of corrosive media and improving the coating's physical barrier properties. Simultaneously, due to its small size effect, graphene can fill defects in the coating, reducing porosity, enhancing density, and further delaying or preventing corrosive agents from penetrating the substrate surface. The interlayer lubrication of graphene layers, combined with its sheet-like structure, divides the coating into numerous small sections, effectively reducing internal stress and dissipating fracture energy, thereby improving the coating's flexibility, impact resistance, and wear resistance. Furthermore, graphene's conjugated structure gives it high electron mobility, exhibiting excellent electrical conductivity. Its sheet-like structure also ensures good electrochemical contact between coating layers, forming a conductive network and providing superior electrochemical protection. Therefore, the composite material made by combining graphene and waterborne epoxy resin has the advantages of both and has good application value in environmental protection and other aspects.

[0005] Chinese invention patent application number 202111504985.8 discloses "a graphene-modified waterborne epoxy anticorrosive coating and its preparation method," comprising two components, A and B, in a mass ratio of (3-5):1. Component A, by weight, consists of: 30-45 parts waterborne epoxy resin, 1-2 parts graphene slurry, 45-60 parts waterborne pigment, 0.5-3 parts additives, and 0.1-2 parts water. Component B, by weight, consists of: 15-20 parts waterborne epoxy curing agent, 1-3 parts co-solvent, and 1-4 parts water. The waterborne epoxy resin includes Huntsman's 3961-1 waterborne epoxy resin emulsion. However, this patent focuses on improving anticorrosive performance without addressing the optimization of high thermal conductivity, failing to achieve a dual synergistic enhancement of thermal conductivity and anticorrosiveness. This results in limited overall thermal protection performance, unable to meet the needs of high thermal conductivity applications such as heat exchangers and solar panels. Summary of the Invention

[0006] The purpose of this invention is to solve the industry problems of insufficient long-term anti-corrosion performance and poor thermal conductivity of existing waterborne epoxy anti-corrosion paints, as well as the difficulty in stable dispersion and easy agglomeration of high thermal conductivity fillers (such as graphene) in high solid content waterborne epoxy systems, which affect the density of the coating and the long-term anti-corrosion effect. The invention provides a waterborne epoxy graphene coating that has excellent thermal conductivity, ultra-long corrosion resistance and good stability.

[0007] To achieve the above objectives, the present invention provides a water-based epoxy high thermal conductivity graphene coating, comprising component A and component B; wherein, component A comprises the following by mass percentage: 45% waterborne epoxy resin; Defoamer 0.1%; Dispersant 1%; Titanium dioxide 10%; Graphene 0.5-1.5%; Silane coupling agent 1-2%; Special rust-preventive filler 8-10%; Stone-ground powder 5%; Composite iron-titanium powder 10%; Expanded microbeads 2-4%; Organic bentonite 0.4%; Leveling agent 0.5%; Deionized water 12.5-14.5%; Component B is an anhydrous diluent amine curing agent.

[0008] Preferably, the defoamer is an organosilicon defoamer, such as BYK-024 or Tego-825; the dispersant is a polyether polymeric dispersant, such as BYK-190 or Tego-750W; and the leveling agent is a polyether-modified polydimethylsiloxane leveling agent, such as BYK-333 or Tego-450.

[0009] Preferably, the expanded microspheres have a particle size of 5-50 μm.

[0010] Preferably, the graphene is modified with a silane coupling agent.

[0011] This invention also provides a method for preparing a waterborne epoxy high thermal conductivity graphene coating, comprising the following steps: S1. Graphene and silane coupling agent are mixed at a mass ratio of 1:(1-2) and modified to obtain modified graphene. S2. Mix waterborne epoxy resin, defoamer, dispersant, titanium dioxide, modified graphene, special rust-preventive filler, stone mill powder, composite iron-titanium powder, expanded microspheres, organic bentonite, leveling agent and deionized water, and disperse at high speed to obtain component A; S3. Mix component A and component B at a mass ratio of 4:1 to obtain a water-based epoxy high thermal conductivity graphene coating.

[0012] Preferably, the modification process in step S1 is as follows: first, graphene is dispersed in 50 times its mass of ethanol or water at a volume ratio of 1:1, and ultrasonically treated for 30 minutes at a power of 800W; then, a silane coupling agent is added, and the mixture is mechanically stirred at 500rpm in a 60°C water bath for 2 hours; after the reaction is completed, the mixture is centrifuged, washed three times with deionized water, and dried in a vacuum drying oven at 80°C for 6 hours to obtain modified graphene.

[0013] Preferably, step S2 specifically involves: adding deionized water, dispersant, and half the amount of defoamer to the waterborne epoxy resin under low-speed stirring at 400 rpm, and stirring for 10 minutes; then sequentially adding titanium dioxide, special rust-preventive filler, stone mill powder, composite iron-titanium powder, and organic bentonite, increasing the speed to 1200 rpm, and dispersing for 20 minutes; finally adding the modified graphene, expanded microspheres, leveling agent, and the remaining defoamer obtained in step S1, dispersing at high speed at 1500 rpm for 35 minutes, and grinding with a sand mill to a fineness ≤60 μm to obtain component A.

[0014] The present invention also provides an application of waterborne epoxy high thermal conductivity graphene coating in heat exchangers or solar panel protection.

[0015] Preferably, the specific steps are as follows: after the water-based epoxy high thermal conductivity graphene coating has been cured for 15 minutes, it is applied to the surface of the substrate by brushing, rolling or spraying, and cured at room temperature for ≤4 hours for surface dryness and ≤24 hours for actual dryness, or baked at 80°C for 30 minutes to fully cure, thus forming a coating.

[0016] Compared with the prior art, the advantages of this invention are: This invention utilizes silane coupling agents to surface modify graphene, effectively solving its dispersion stability problem within the system. Through scientific compounding with specific components such as composite iron-titanium powder and expanded microspheres, a synergistic effect is achieved. This coating exhibits excellent thermal conductivity (≥1.5 W / (m·K)), outstanding corrosion resistance (salt spray resistance ≥1000h), good electrical conductivity, and physical and mechanical properties. Using high-performance graphene as the key functional material results in lower production costs and significantly improved overall performance. It can be used for surface coating of heat exchangers and solar panels, providing superior thermal conductivity protection and excellent thermal energy conversion efficiency. Detailed Implementation

[0017] The terms used in this invention, unless otherwise stated, generally have the meanings commonly understood by those skilled in the art.

[0018] In the following embodiments, various processes and methods not described in detail are conventional methods known in the art.

[0019] The reagents used in the following examples were obtained through common commercial channels. Experimental procedures and conditions not specified are in accordance with conventional procedures and conditions in the art.

[0020] The specific implementation of the present invention will be described below with reference to the embodiments.

[0021] Example 1 The components of Example 1 provided by this invention are shown in Table 1 below, wherein the defoamer is BYK-024, the dispersant is BYK-190, and the leveling agent is BYK-333. Table 1 Component A Percentage of mass (%) Waterborne epoxy resin 45 Defoamer (BYK-024) 0.1 Dispersant (BYK-190) 1 Titanium dioxide 10 graphene 0.5 Silane coupling agent (KH-560) 1 Special rust-preventive filler (zinc phosphate) 10 stone mill powder 5 Composite iron-titanium powder 10 Expanded microspheres (particle size 20μm) 2 Organic bentonite 0.4 Leveling agent (BYK-333) 0.5 Deionized water 14.5 Component B Parts by weight (relative to 100 parts of component A) Anhydrous diluent amine curing agent (Cardolite 2556) 25 Example 2 The components of Example 2 provided by this invention are shown in Table 2 below, wherein the defoamer is Tego-825, the dispersant is Tego-750W, and the leveling agent is Tego-450. Table 2 Component A Percentage of mass (%) Waterborne epoxy resin 45 Defoamer (Tego-825) 0.1 Dispersant (Tego-750W) 1 Titanium dioxide 10 graphene 1 Silane coupling agent (KH-560) 1.5 Special rust-preventive filler (aluminum tripolyphosphate) 9 stone mill powder 5 Composite iron-titanium powder 10 Expanded microspheres (30μm particle size) 3 Organic bentonite 0.4 Leveling agent (Tego-450) 0.5 Deionized water 13.5 Component B Parts by weight (relative to 100 parts of component A) Anhydrous diluent amine curing agent (Cardolite 2556) 25 Example 3 The components of Example 3 provided by the present invention are shown in Table 3 below, wherein the defoamer is BYK-024, the dispersant is BYK-190, and the leveling agent is BYK-333.

[0022] Table 3 Component A Percentage of mass (%) Waterborne epoxy resin 45 Defoamer (BYK-024) 0.1 Dispersant (BYK-190) 1 Titanium dioxide 10 graphene 1.5 Silane coupling agent (KH-560) 2 Special rust-preventive filler (zinc phosphate) 8 stone mill powder 5 Composite iron-titanium powder 10 Expanded microspheres (particle size 40μm) 4 Organic bentonite 0.4 Leveling agent (BYK-333) 0.5 Deionized water 12.5 Component B Parts by weight (relative to 100 parts of component A) Anhydrous diluent amine curing agent (Cardolite 2556) 25 Experimental examples and effect comparison The coatings obtained in Examples 1-3 above were subjected to performance tests with the following comparative examples, and the results are shown in Table 4.

[0023] Comparative Example 1: Ordinary water-based epoxy anti-corrosion coating without graphene and composite iron-titanium powder.

[0024] Comparative Example 2: Contains 1% graphene, but has not been modified with silane coupling agent.

[0025] Comparative Example 3: Contains 1% modified graphene, but does not contain composite iron-titanium powder.

[0026] Test method: Thermal conductivity: laser flare method; Salt spray resistance: ASTM B117 standard; Adhesion: Pull-off adhesion tester; Impact resistance: GB / T 1732-1993; Paint film appearance: visual inspection.

[0027] Table 4: Performance Comparison Test Results Test Project Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Thermal conductivity [W / (m·K)] 0.2 0.8 0.9 1.3 1.5 1.6 Salt spray resistance (h) 300 400 450 900 1000 1000 Adhesion (MPa) 3.5 4.0 4.2 4.8 5.0 4.9 Impact resistance (cm) 40 45 45 50 50 50 Paint film appearance smooth There are particles smooth Smooth Smooth Smooth This invention modifies the surface of graphene using a silane coupling agent, thus solving the problem of graphene dispersion stability in high solids systems. According to the data in the table, the thermal conductivity of the coating of this invention can reach 1.6 W / (m·K), the salt spray resistance can reach 1000h, the adhesion is above 4.5MPa, and the impact resistance is 50cm.

[0028] The above is a detailed description of the embodiments, which is intended to enable those skilled in the art to correctly understand and use the present invention. Any improvements or modifications to technical solutions obtained by those skilled in the art based on the present invention and on the existing technology, without innovative effort but only through analysis, analogy, or limited enumeration, should be within the scope of protection defined by the claims.

Claims

1. A water-based epoxy high thermal conductivity graphene coating, characterized in that, It includes component A and component B; wherein, component A comprises, by mass percentage, the following: 45% waterborne epoxy resin; Defoamer 0.1%; Dispersant 1%; Titanium dioxide 10%; Graphene 0.5-1.5%; Silane coupling agent 1-2%; Special rust-preventive filler 8-10%; Stone-ground powder 5%; Composite iron-titanium powder 10%; Expanded microbeads 2-4%; Organic bentonite 0.4%; Leveling agent 0.5%; Deionized water 12.5-14.5%; Component B is an anhydrous diluent amine curing agent.

2. The water-based epoxy high thermal conductivity graphene coating as described in claim 1, characterized in that, The defoamer is an organosilicon defoamer; the dispersant is a polyether polymeric dispersant; and the leveling agent is a polyether-modified polydimethylsiloxane leveling agent.

3. The waterborne epoxy high thermal conductivity graphene coating as described in claim 1, characterized in that, The expanded microspheres have a particle size of 5-50 μm.

4. The water-based epoxy high thermal conductivity graphene coating as described in claim 1, characterized in that, The graphene was modified with a silane coupling agent.

5. A method for preparing a waterborne epoxy high thermal conductivity graphene coating as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Graphene and silane coupling agent are mixed at a mass ratio of 1:(1-2) and modified to obtain modified graphene. S2. Waterborne epoxy resin, defoamer, dispersant, titanium dioxide, modified graphene, special rust-preventive filler, stone mill powder, composite iron-titanium powder, expanded microspheres, organic bentonite, leveling agent and deionized water are mixed and dispersed and ground at high speed to obtain component A; S3. Mix component A and component B at a mass ratio of 4:1 to obtain a water-based epoxy high thermal conductivity graphene coating.

6. The method for preparing a waterborne epoxy high thermal conductivity graphene coating as described in claim 5, characterized in that, The specific process of modification in step S1 is as follows: First, graphene is dispersed in 50 times its mass of ethanol or water and mixed at a volume ratio of 1:

1. After ultrasonic treatment, a silane coupling agent is added, and the mixture is stirred and reacted under heating conditions. After the reaction is completed, the graphene is obtained by centrifugation, washing and drying.

7. The method for preparing a waterborne epoxy high thermal conductivity graphene coating as described in claim 5, characterized in that, Step S2 specifically involves: adding deionized water, dispersant, and half the amount of defoamer to the waterborne epoxy resin under low-speed stirring, and stirring to mix; then adding titanium dioxide, special anti-rust filler, stone mill powder, composite iron-titanium powder, and organic bentonite in sequence, and stirring and dispersing at medium speed; finally adding the modified graphene, expanded microspheres, leveling agent, and the remaining defoamer obtained in step S1, stirring and dispersing at high speed, and grinding with a sand mill to a fineness ≤60μm to obtain component A.

8. The method for preparing a waterborne epoxy high thermal conductivity graphene coating as described in claim 7, characterized in that, The stirring speed is 400 rpm for 10 minutes at low speed; 1200 rpm for 20 minutes at medium speed; and 1500 rpm for 35 minutes at high speed.

9. The application of a waterborne epoxy high thermal conductivity graphene coating as described in any one of claims 1-4 in a heat exchanger or solar panel.

10. The application of the waterborne epoxy high thermal conductivity graphene coating as described in claim 9, characterized in that, The specific steps are as follows: after the water-based epoxy high thermal conductivity graphene coating has been cured for 15 minutes, it is applied to the substrate surface by brushing, rolling or spraying. The surface drying time is ≤4 hours and the actual drying time is ≤24 hours at room temperature, or it is baked at 80℃ for 30 minutes to fully cure and form a coating.