Conductive coatings, their preparation methods and applications

Abstract

This invention relates to the field of conductive materials technology, specifically to a conductive coating and its preparation method and application. The conductive coating comprises: a carbon-based conductive material, a dispersant, additives, a solvent, and a resin; the dispersant includes at least one block polyether dispersant, which has the structure shown in formula (1): wherein the ratio of m to n is 0.3-3:1; the weight-average molecular weight of the block polyether dispersant does not exceed 2000 g / mol; R has the structure shown in formula (2), wherein R1 is a C1-C10 alkylene group, and R2, R3, and R4 are each independently selected from C1-C3 alkyl groups. This invention, through the compounding of carbon-based conductive material, dispersant, and other components, greatly improves the conductivity, stability, adhesion, hydrophobicity, and anti-corrosion performance of the coating, and the coating film exhibits good bonding with the substrate.

Description

Technical Field

[0001] This invention relates to the field of conductive materials technology, specifically to a conductive coating, its preparation method, and its application. Background Technology

[0002] In recent years, with the rapid development of modern science and technology, conductive coatings, as a new type of special functional coating, have been widely used in fields such as power transmission equipment, petrochemicals, electronics, and aerospace. Conductive coatings can eliminate static charges in the substrate and conduct current, while forming a protective layer on the substrate surface, effectively blocking corrosive media from damaging the substrate. They have good conductivity, corrosion resistance, electromagnetic shielding, and adhesion, and are considered an important direction for the development of powder coatings, possessing broad market prospects.

[0003] Conductive coatings are classified into intrinsic and doped types based on their conductivity mechanism. Intrinsic conductive coatings use conductive polymers as the basic film-forming material, requiring no additional conductive fillers such as polyaniline, polyacetylene, and polypyrrole. However, the limited variety of these materials, along with their difficulty in purification and application, restricts their application. Doped conductive coatings use non-conductive polymers as the film-forming resin and are filled with highly conductive materials to create a conductive coating. The filler is a key factor determining the performance of the conductive coating system. Currently, conductive fillers are mainly classified into three types: carbon-based, metal-based, and metal oxide-based, with carbon-based materials being the most widely used.

[0004] There are precedents for preparing functional coatings by adding other effective components to carbon-based materials. CN109206961A discloses a graphene conductive and thermally conductive coating and its preparation method, comprising 1-10 parts graphene, 2-5 parts carbon nanotubes, 2-5 parts sodium silicate, 1-3 parts paint oil, 1-3 parts tung oil, 0.3-1.5 parts maleic anhydride, 3-5 parts dispersant, 1-3 parts acrylic resin, 0.05-0.5 parts composite drying agent, 1-3 parts coupling agent, 0.2-1 parts silica, 0.2-1 parts composite additive, 0.5-2 parts modified cellulose, 1.5-2 parts zeolite powder, 1-8 parts thermally conductive metal powder, and 40-60 parts ethanol. However, the coatings prepared so far often suffer from poor dispersibility and the floating of carbon-based materials, resulting in voids and unevenness on the coating surface, which can lead to coating failure in severe cases.

[0005] Therefore, it is particularly important to develop a coating product with excellent conductivity and stability, and to promote the application of highly conductive carbon-based conductive coatings. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of poor conductivity and poor dispersibility in existing coatings, and to provide a conductive coating, its preparation method, and its application. By compounding carbon-based conductive materials, dispersants, and other components, the conductivity, stability, adhesion, hydrophobicity, and anti-corrosion properties of the coating are greatly improved, and the coating film exhibits good bonding with the substrate.

[0007] To achieve the above objectives, a first aspect of the present invention provides a conductive coating comprising: a carbon-based conductive material, a dispersant, an additive, a solvent, and a resin;

[0008] The dispersant comprises at least one of block polyether dispersants, the block polyether dispersant having the structure shown in formula (1):

[0009]

[0010] Wherein, the ratio of m to n is 0.3-3∶1; the weight-average molecular weight of the block polyether dispersant does not exceed 2000 g / mol;

[0011] R has the structure shown in equation (2).

[0012]

[0013] R1 is selected from -(CH2). x1 -、-CH2-CH(CH3)-(CH2) x2 -, -CH2-C(CH3)2-(CH2) x3 -、-CH(CH3)-(CH2) x4 -、-C(CH3)2-(CH2) x5 -、-C(CH3)(CH2CH3)-(CH2) x6 -or -C(CH3)(C3H7)-(CH2) x7 - where x1-x7 are each independently selected from 0, 1, 2, 3 or 4; R2, R3, R4 are each independently selected from C1-C3 alkyl groups.

[0014] A second aspect of the present invention provides a method for preparing the conductive coating of the present invention, wherein the method includes:

[0015] (1) Mix carbon-based conductive material, water, and dispersant, and grind to obtain a slurry;

[0016] (2) Mix the slurry with resin and additives and stir to obtain the coating.

[0017] A third aspect of the present invention provides an application of the conductive coating described herein in screen printing.

[0018] Through the above technical solution, the conductive coating of the present invention solves the problem of carbon-based conductive material floating by compounding carbon-based conductive material, dispersant and other components, and has a better effect; it greatly improves the conductivity, stability, adhesion, hydrophobicity and anti-corrosion performance of the coating, and the coating has a better bonding effect with the substrate after film formation.

[0019] The preparation process of the conductive coating of the present invention, including the grinding and stirring processes, exhibits the characteristics of simple process conditions and ease of large-scale production. Attached Figure Description

[0020] Figure 1 This is the 1H NMR spectrum of dispersant A1 in Example 1;

[0021] Figure 2 This is the carbon NMR spectrum of dispersant A1 in Example 1;

[0022] Figure 3 This is the two-dimensional hydrocarbon NMR HMBC spectrum of dispersant A1 in Example 1;

[0023] Figure 4 This is the total particle flow chromatogram of dispersant A1 in Example 1;

[0024] Figure 5 This is a scanning electron microscope image of the highly conductive carbon-based material in Example 1;

[0025] Figure 6 This is a digital photograph of the highly conductive carbon-based conductive coating prepared in Example 1;

[0026] Figure 7 This is a scanning electron microscope image of the highly conductive carbon-based conductive coating prepared in Example 1. Detailed Implementation

[0027] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0028] The first aspect of the present invention provides a conductive coating comprising: a carbon-based conductive material, a dispersant, an additive, a solvent, and a resin;

[0029] The dispersant comprises at least one of block polyether dispersants, the block polyether dispersant having the structure shown in formula (1):

[0030]

[0031] Wherein, the ratio of m to n is 0.3-3:1; the weight-average molecular weight of the block polyether dispersant does not exceed 2000 g / mol;

[0032] R has the structure shown in equation (2).

[0033]

[0034] R1 is selected from -(CH2). x1 -、-CH2-CH(CH3)-(CH2) x2 -, -CH2-C(CH3)2-(CH2) x3 -、-CH(CH3)-(CH2) x4 -、-C(CH3)2-(CH2) x5 -、-C(CH3)(CH2CH3)-(CH2) x6 -or -C(CH3)(C3H7)-(CH2) x7 - where x1-x7 are each independently selected from 0, 1, 2, 3 or 4;

[0035] R2, R3, and R4 are each independently selected from C1-C3 alkyl groups.

[0036] In the block polyether dispersant provided by the present invention, RO- is a starting end group introduced into the polymer structure by the polyether initiator, which sequentially connects ethylene oxide block and propylene oxide block. The other end of the polymer main chain is capped with a propylene oxide block and the end is a hydroxyl group.

[0037] In this invention, R2, R3, and R4 are each independently selected from C1-C3 alkyl groups, wherein the alkyl group can be a straight-chain or branched alkyl group, including but not limited to methyl, ethyl, n-propyl, or isopropyl, and more preferably, R2, R3, and R4 are all methyl.

[0038] According to a preferred embodiment of the present invention, R is selected from -CH2CH2CH(CH3)CH2C(CH3)2CH3, -C(CH2CH3)(CH2CH2CH3)CH3, -CH2CH2C(CH3)2CH2CH3 or -C(CH3)2CH2CH3; preferably -CH2CH2CH(CH3)CH2C(CH3)2CH3.

[0039] According to a preferred embodiment of the present invention, the ratio of m to n is 0.5-2:1.

[0040] According to a preferred embodiment of the present invention, m is 1-14, preferably 3-9; n is 1-14, preferably 3-9.

[0041] In this invention, the degree of polymerization is obtained by NMR analysis.

[0042] According to a preferred embodiment of the present invention, the weight-average molecular weight of the block polyether dispersant is 450-1500 g / mol.

[0043] In this invention, the molecular weight is obtained by gas chromatography-mass spectrometry analysis.

[0044] In this invention, the surface tension reduction effect of the dispersant is determined by the surface tension of the aqueous solution of the dispersant. According to a preferred embodiment of the invention, the block polyether is mixed with water to obtain an aqueous solution with a mass concentration of 0.1%, wherein the static surface tension of the aqueous solution is 23-40 mN / m, preferably 25-30 mN / m; and the dynamic surface tension of the aqueous solution is 25-42 mN / m, preferably 27-40 mN / m.

[0045] In this invention, the static surface tension is obtained by testing with a static surface tension meter, and the dynamic surface tension is obtained by testing with a dynamic surface tension meter.

[0046] According to a preferred embodiment of the present invention, the contact angle of the dispersant with the solid silicon wafer is less than 80°, preferably 20-50°. The solid silicon wafer is a commercially available monocrystalline silicon wafer, and the contact angle is measured using a contact angle measuring instrument.

[0047] According to a preferred embodiment of the present invention, the block polyether dispersant is selected from at least one of (CH3)3CCH2CH(CH3)CH2CH2O(C2H4O)3(C3H6O)3H, CH3(CH2CH2CH3)(CH2CH3)CO(C2H4O)3(C3H6O)6H, CH3CH2C(CH3)2CH2CH2O(C2H4O)8(C3H6O)4H, and CH3CH2(CH3)2CO(C2H4O)4(C3H6O)8H, preferably (CH3)3CCH2CH(CH3)CH2CH2O(C2H4O)3(C3H6O)3H.

[0048] This invention provides a method for preparing the block polyether dispersant, comprising the following steps:

[0049] (1) In the presence of a catalyst, under the conditions of the first polymerization reaction, the initiator and ethylene oxide are brought into contact to carry out the first polymerization reaction;

[0050] (2) Under the conditions of the second polymerization reaction, the product obtained from the first polymerization reaction is subjected to a second polymerization reaction with propylene oxide;

[0051] Wherein, the molar ratio of ethylene oxide to initiator is 30-200:1, and the molar ratio of ethylene oxide to propylene oxide is 0.3-3:1;

[0052] The initiator has the structure shown in formula (3).

[0053]

[0054] Wherein, R1 is a C1-C10 alkylene group, and R2, R3, and R4 are each independently selected from C1-C3 alkyl groups.

[0055] It should be noted that in the preparation method of the present invention, the order of the first polymerization reaction and the second polymerization reaction is significantly affected by the product structure and performance. In the first polymerization reaction, ethylene oxide can undergo ring-opening polymerization with the initiator to obtain a first block copolymer containing ethylene oxide blocks. Then, the first block copolymer is subjected to a second polymerization reaction with propylene oxide to obtain a dispersant with a block polyether structure as shown in formula (1).

[0056] According to a preferred embodiment of the present invention, R1 is selected from -(CH2). x1 -、-CH2-CH(CH3)-(CH2) x2 -, -CH2-C(CH3)2-(CH2) x3 -、-CH(CH3)-(CH2) x4 -、-C(CH3)2-(CH2) x5 -、-C(CH3)(CH2CH3)-(CH2) x6 -or -C(CH3)(C3H7)-(CH2) x7 - where x1-x7 are each independently selected from 0, 1, 2, 3 or 4.

[0057] In this invention, R2, R3, and R4 are each independently selected from C1-C3 alkyl groups, wherein the alkyl group can be a straight-chain or branched alkyl group, including but not limited to methyl, ethyl, n-propyl, or isopropyl, and more preferably, R2, R3, and R4 are methyl.

[0058] According to a preferred embodiment of the present invention, the initiator is selected from at least one of 3,5,5-trimethyl-1-hexanol, 2,3,3-trimethyl-2-butanol, 2,2-dimethyl-1-propanol, 3,3-dimethyl-1-butanol, 2,3-dimethyl-3-pentanol, 2-methyl-2-butanol, and 3,3-dimethyl-1-pentanol, preferably 3,5,5-trimethyl-1-hexanol and / or 2,3,3-trimethyl-2-butanol.

[0059] According to a preferred embodiment of the present invention, the molar ratio of ethylene oxide to the initiator is 50-150:1, such as typical but not limiting ratios like 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 110:1, 120:1, 130:1, 140:1, and 150:1. A molar ratio of ethylene oxide to the initiator within the above-mentioned preferred range is beneficial for obtaining ethylene oxide with a suitable degree of polymerization and improving the dispersion effect of the dispersant.

[0060] According to a preferred embodiment of the present invention, the molar ratio of ethylene oxide to propylene oxide is 0.5-2:1. It is understood that the amounts of each component are sufficient to ensure that the resulting dispersant has the desired composition of its structural units.

[0061] In this invention, the selection range of the catalyst is relatively wide; any catalyst capable of catalyzing the ring-opening polymerization of ethylene oxide and propylene oxide can be used. It can be selected from conventional alkali metal or alkaline earth metal catalysts well known to those skilled in the art. Preferably, the catalyst is selected from at least one of potassium hydroxide, sodium hydroxide, barium hydroxide, and calcium acetate, with potassium hydroxide and / or sodium hydroxide being more preferred. Using the above-mentioned preferred catalyst helps to reduce production costs.

[0062] According to a preferred embodiment of the present invention, the amount of catalyst used is 2-6 wt% of the total amount of ethylene oxide and propylene oxide, preferably 2.5-4 wt%.

[0063] According to a preferred embodiment of the present invention, the first polymerization reaction conditions include: a reaction temperature of 110-160°C, preferably 120-150°C; a reaction pressure of 0-0.4 MPa, preferably 0.2-0.4 MPa; and a reaction time of 10-60 min, preferably 30-40 min.

[0064] According to a preferred embodiment of the present invention, the second polymerization reaction conditions include: a reaction temperature of 110-160°C, preferably 130-150°C; a reaction pressure of 0-0.4 MPa, preferably 0.2-0.4 MPa; and a reaction time of 10-60 min, preferably 20-30 min.

[0065] In this invention, it is understood that during the first or second polymerization reaction, as the reaction proceeds, the pressure in the reaction system gradually decreases, and the temperature in the reaction system increases due to the exothermic reaction, as long as the pressure and temperature during the reaction process meet the above-mentioned pressure and temperature range.

[0066] In this invention, the first polymerization reaction and the second polymerization reaction can be carried out using conventional operating methods and reactors in the art, and this invention does not have any particular limitations. Preferably, the first polymerization reaction and the second polymerization reaction are carried out in a high-temperature and high-pressure reactor.

[0067] According to a preferred embodiment of the present invention, the first polymerization reaction includes: first, adding a catalyst and an initiator into a reactor, removing oxygen and drawing a vacuum, then adjusting to the first polymerization reaction conditions, and then adding ethylene oxide to carry out the first polymerization reaction.

[0068] According to a preferred embodiment of the present invention, the deoxygenation operation can be carried out using conventional methods in the art, such as introducing an inert gas into the reactor for displacement. Preferably, the inert gas is nitrogen.

[0069] In this invention, the deoxygenation and vacuuming steps can optionally be repeated. Preferably, the deoxygenation and vacuuming steps are repeated at least twice.

[0070] According to a preferred embodiment of the present invention, the first polymerization reaction and the second polymerization reaction are each carried out independently under stirring conditions, wherein the stirring rate is each independently 1500-3000 rpm, preferably 1800-2500 rpm.

[0071] According to a preferred embodiment of the present invention, the preparation method further includes: sequentially subjecting the product of the second polymerization reaction to impurity removal, neutralization, adsorption, and filtration to obtain the dispersant. The impurity removal, neutralization, adsorption, and filtration can be performed using conventional operations in the art, and the present invention does not have any special requirements for them. For example, unreacted monomers and small molecules in the system can be removed by vacuuming.

[0072] In this invention, resin is a substance used in coatings to provide adhesion and facilitate coating curing. Its main function is to adhere carbon-based materials to the surface to be coated, forming a robust coating layer; this achieves conductivity while protecting the carbon-based materials from environmental influences and mechanical damage.

[0073] In this invention, the additives have multiple functions, including improving the fluidity of the coating, increasing adhesion, and improving durability. Their effects can vary depending on the specific formulation and coating requirements.

[0074] According to a preferred embodiment of the present invention, the conductive coating comprises, by weight: 1-10 parts by weight of carbon-based material, 0.01-2 parts by weight of dispersant, 0.01-4 parts by weight of resin, 0.01-1 parts by weight of additives, and 10-100 parts by weight of solvent.

[0075] In this invention, the range of resins that can be selected is relatively wide, as long as they have good adhesion and stability. According to a preferred embodiment of this invention, the resin is selected from at least one of polyurethane resin, acrylic resin, epoxy resin and polyether resin, preferably epoxy resin.

[0076] In this invention, the range of types of additives that can be selected is relatively wide, as long as they can improve the dispersibility and process performance of the coating. According to a preferred embodiment of this invention, the additive is selected from C2-C3 polyols. Preferably, the additive is selected from at least one of ethylene glycol, 1,2-propanediol, 1,3-propanediol and glycerol, and preferably ethylene glycol.

[0077] In this invention, the range of types of carbon-based conductive materials that can be selected is relatively wide. According to a preferred embodiment of this invention, the carbon-based conductive material is selected from at least one of conductive carbon black, graphene, and carbon nanotubes.

[0078] According to a preferred embodiment of the present invention, the carbon-based conductive material has a D50 < 2 μm. The D50 (median particle size) is obtained by measuring the particle size using a Malvern nanoparticle size analyzer.

[0079] According to a preferred embodiment of the present invention, the carbon-based conductive material has a carbon content of 99% or greater.

[0080] According to a preferred embodiment of the present invention, the conductivity is greater than or equal to 600 S / cm.

[0081] In this invention, the conductivity is obtained by pressure-based testing.

[0082] According to a preferred embodiment of the present invention, the carbon-based conductive material is graphene.

[0083] According to a preferred embodiment of the present invention, the graphene is selected from powdered graphene, which has a three-dimensional structure and is an accumulation of graphene sheets. The properties of the powdered graphene are as follows: it has D and G peaks in the Raman spectrum, ID / IG is below 0.10, and electrical conductivity is 600-5000 S / cm.

[0084] According to a preferred embodiment of the present invention, the ID / IG ratio in the Raman spectrum of the powdered graphene is 0.01-0.10, more preferably 0.03-0.10.

[0085] According to a preferred embodiment of the present invention, the graphene sheet has 110 layers and a thickness of 0.5-3.0 nm.

[0086] According to a preferred embodiment of the present invention, the powdered graphene has a three-dimensional cage-like structure, and preferably, the powdered graphene is an accumulation of petal-shaped graphene sheets.

[0087] According to a preferred embodiment of the present invention, the carbon content of the powdered graphene is ≥99.90%, preferably 99.90% or 99.95%, based on the mass of the powdered graphene.

[0088] According to a preferred embodiment of the present invention, the oxygen content of the powdered graphene is below 300 ppm, based on the mass of the powdered graphene.

[0089] In this invention, the carbon and oxygen content in graphene is obtained by elemental analysis.

[0090] According to a preferred embodiment of the present invention, the specific surface area of ​​the powdered graphene is 50300 m². 2 / g, preferably 100250m 2 / g.

[0091] According to a preferred embodiment of the present invention, the tap density of the powdered graphene is 0.02-0.04 g / cm³. 3 .

[0092] According to a preferred embodiment of the present invention, the electrical conductivity of the powdered graphene is 1500-4000 S / cm, preferably 2000-3500 S / cm.

[0093] According to a preferred embodiment of the present invention, the solvent is water.

[0094] A second aspect of the present invention provides a method for preparing the conductive coating of the present invention, wherein the method includes:

[0095] (1) Mix carbon-based conductive material, water, and dispersant, and grind to obtain a slurry;

[0096] (2) Mix the slurry with resin and additives and stir to obtain the coating.

[0097] According to a preferred embodiment of the present invention, in step (1), the carbon-based conductive material is ground to make D50 < 2 μm.

[0098] According to a preferred embodiment of the present invention, in step (2), the stirring speed is 1500-2000 rpm and the stirring time is 10-30 min.

[0099] A third aspect of the present invention provides an application of the conductive coating described herein in screen printing.

[0100] The present invention will be described in detail below through embodiments.

[0101] Static surface tension is obtained by measuring static surface tension, while dynamic surface tension is obtained by measuring dynamic surface tension.

[0102] The paint film testing method is as follows:

[0103] Volume resistivity experiment: The prepared highly conductive carbon-based conductive coating was applied to a PET film, and the conductivity of the coating after curing and drying was tested using a volume resistivity tester.

[0104] Preparation Example 1

[0105] (1) Add 1g of 3,5,5-trimethyl-1-hexanol and 2g of potassium hydroxide to a high-temperature and high-pressure reactor, and seal the reactor. Before heating, purge and replace with nitrogen gas, then evacuate. Repeat this process at least twice. Start stirring and heat to 125°C. Add 40g of ethylene oxide to carry out the first polymerization reaction (the molar ratio of ethylene oxide to initiator is approximately 130:1). Control the reaction temperature at 140-150°C and the reaction pressure at 0.3-0.4 MPa. Continue stirring for 40 minutes until the pressure drops to 0 MPa.

[0106] (2) Heat the high-temperature and high-pressure reactor to 125°C, add 40g of propylene oxide to carry out the second polymerization reaction (the molar ratio of ethylene oxide to propylene oxide is 1.32:1), control the reaction temperature at 140-150°C, and control the reaction pressure at 0.3-0.4MPa. Stir for 30min to reduce the pressure to 0MPa.

[0107] (3) Turn on the vacuum pump and maintain it for 20 minutes to remove unreacted monomers and small molecules from the system. After the temperature of the reactor drops below 50°C, remove potassium hydroxide through neutralization, adsorption, and filtration to obtain dispersant A1.

[0108] The obtained dispersant A1 was analyzed by carbon NMR and hydrogen NMR spectra and identified as a block polyether dispersant containing the following structural composition. The hydrogen NMR spectrum of dispersant A1 is shown below. Figure 1 As shown, the carbon NMR spectrum of dispersant A1 is as follows: Figure 2 As shown;

[0109] like Figure 3 The two-dimensional carbon-hydrogen correlation spectrum of the nuclear magnetic resonance HMBC shown can be seen to have three carbon signals related to the hydrogen of the terminal hydroxyl group, proving that the terminal hydroxyl group comes from the propylene oxide block.

[0110]

[0111] Where m = 3, n = 3, m:n = 1, the total particle flow chromatogram of dispersant A1 is as follows: Figure 4 As shown, the molecular weight of the dispersant was measured to be 480 g / mol.

[0112] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 28.93 mN / m; the dynamic surface tension is 35.06 mN / m.

[0113] The contact angle of the dispersant on a commercially available monocrystalline silicon wafer was tested using a contact angle meter. The contact angle of dispersant A1 on the solid silicon wafer was 25.5°.

[0114] Preparation Example 2

[0115] (1) Add 1g of CH3(CH2CH2CH3)(CH2CH3)COH and 2g of potassium hydroxide to a high-temperature and high-pressure reactor, and seal the reactor. Before heating, purge and replace with nitrogen gas, then evacuate. Repeat this process at least twice. Start stirring and heat to 125℃. Add 40g of ethylene oxide to carry out the first polymerization reaction (the molar ratio of ethylene oxide to initiator is approximately 105:1). Control the reaction temperature at 130-140℃ and the reaction pressure below 0.3-0.4MPa. After the pressure drops, continue stirring for 30min until the pressure drops to 0MPa.

[0116] (2) Heat the high-temperature and high-pressure reactor to 130°C, add 100g of propylene oxide to carry out the second polymerization reaction (the molar ratio of ethylene oxide to propylene oxide is 0.53:1), control the reaction temperature at 140-150°C, and control the reaction pressure at 0.3-0.4MPa. Stir continuously for 20min until the pressure drops to 0MPa.

[0117] (3) Turn on the vacuum pump and maintain it for 20 minutes to remove unreacted monomers and small molecules from the system. After the temperature of the reactor drops to below 50°C, remove potassium hydroxide by neutralization, adsorption, and filtration to obtain dispersant A2, with the structure shown in formula (1), where R is -C(CH2CH3)(CH2CH2CH3)CH3, m:n=0.5:1, m=3, n=6, and M=596g / mol.

[0118] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 29.54 mN / m; the dynamic surface tension is 38.76 mN / m.

[0119] The contact angle of the dispersant on a commercially available monocrystalline silicon wafer was tested using a contact angle meter. The contact angle of dispersant A2 on the solid silicon wafer was 31.2°.

[0120] Preparation Example 3

[0121] (1) Add 1g of CH3CH2(CH3)2COH and 2g of potassium hydroxide to a high-temperature and high-pressure reactor, and seal the reactor. Before heating, purge and replace with nitrogen gas, then evacuate. Repeat this process at least twice. Start stirring and heat to 125℃. Add 80g of ethylene oxide to carry out the first polymerization reaction (the molar ratio of ethylene oxide to initiator is approximately 159.8:1). Control the reaction temperature at 120-130℃ and the reaction pressure at 0.4-0.5MPa. Continue stirring for 60min until the pressure drops to 0MPa.

[0122] (2) Heat the high-temperature and high-pressure reactor to 130°C, add 100g of propylene oxide to carry out the second polymerization reaction (the molar ratio of ethylene oxide to propylene oxide is 1.05:1), control the reaction temperature at 140-150°C, and control the reaction pressure at 0.3-0.4MPa. After the pressure drops, continue stirring for 20min until the pressure drops to 0MPa.

[0123] (3) Turn on the vacuum pump and keep it for 20 minutes to remove unreacted monomers and small molecules from the system. After the temperature of the reactor drops to below 50°C, remove potassium hydroxide by neutralization, adsorption and filtration to obtain dispersant A3, with the structure shown in formula (1), where R is -C(CH3)2CH2CH3, m:n=1:2, m=4, n=8, M=671g / mol;

[0124] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 28.98 mN / m; the dynamic surface tension is 36.74 mN / m.

[0125] The contact angle of the dispersant on a commercially available monocrystalline silicon wafer was tested using a contact angle meter. The contact angle of dispersant A3 on the solid silicon wafer was 41.9°.

[0126] Preparation Example 4

[0127] Following the method of Example 1, except that the amount of ethylene oxide added was 200g and the amount of propylene oxide added was 220g (the molar ratio of ethylene oxide to propylene oxide was 1.2:1), dispersant A4 was prepared with the structure shown in formula (1), wherein R is -CH2CH2CH(CH3)CH2C(CH3)3, m:n = 0.93:1, m = 13, n = 14, and M = 1528g / mol.

[0128] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 32.52 mN / m; the dynamic surface tension is 41.21 mN / m.

[0129] The contact angle of the dispersant on a commercially available monocrystalline silicon wafer was tested using a contact angle meter. The contact angle of dispersant A4 on the solid silicon wafer was 45.1°.

[0130] Preparation Example 5

[0131] The method is the same as in Example 1, except that the amount of 3,5,5-trimethyl-1-hexanol used is 6.5 g, and the molar ratio of ethylene oxide to the initiator is approximately 20:1.

[0132] Dispersant A5 was prepared with the structure shown in formula (1), wherein R is -CH2CH2CH(CH3)CH2C(CH3)3, m:n = 0.6:1, m = 2, n = 3, and M = 400 g / mol.

[0133] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 35.21 mN / m; the dynamic surface tension is 45.56 mN / m.

[0134] The contact angle of the dispersant on commercial monocrystalline silicon wafers was tested using a contact angle meter. The contact angle of dispersant A5 on the solid silicon wafer was 47.5°.

[0135] Preparation Example 6

[0136] (1) Add 1g of CH3CH2C(CH3)2CH2CH2OH and 2g of potassium hydroxide to a high-temperature and high-pressure reactor, and seal the reactor. Before heating, purge and replace with nitrogen gas, then evacuate. Repeat this process at least twice. Start stirring and heat to 125℃. Add 80g of ethylene oxide to carry out the first polymerization reaction (the molar ratio of ethylene oxide to initiator is approximately 211:1). Control the reaction temperature at 140-150℃ and the reaction pressure at 0.3-0.4MPa. Continue stirring for 40min until the pressure drops to 0MPa.

[0137] (2) Heat the high-temperature and high-pressure reactor to 125°C, add 40g of propylene oxide to carry out the second polymerization reaction (the molar ratio of ethylene oxide to propylene oxide is 2.64:1), control the reaction temperature at 140-150°C, and control the reaction pressure at 0.3-0.4MPa. Stir for 30min to reduce the pressure to 0MPa.

[0138] (3) Turn on the vacuum pump and maintain it for 20 minutes to remove unreacted monomers and small molecules from the system. After the temperature of the reactor drops below 50°C, remove potassium hydroxide through neutralization, adsorption, and filtration to obtain dispersant A6.

[0139] The structure is shown in formula (1), where R is -CH2CH2C(CH3)2CH2CH3, m:n = 2:1, m = 8, n = 4, and M = 700 g / mol.

[0140] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 30.77 mN / m; the dynamic surface tension is 40.23 mN / m.

[0141] The contact angle of the dispersant on a commercially available monocrystalline silicon wafer was tested using a contact angle meter. The contact angle of dispersant A4 on the solid silicon wafer was 37.7°.

[0142] Example 1

[0143] 1) Mix 8 parts of conductive graphene (99.9% carbon content, conductivity 634 S / cm, ID / IG = 0.56), 50 parts of water, and 0.05 parts of dispersant A1 until they are uniformly mixed. Add the mixed material to a grinder and grind until D50 < 2 μm to obtain a slurry.

[0144] 2) Add 0.08 parts of epoxy resin and 0.15 parts of ethylene glycol to the slurry and stir in a mixer; adjust the mixer speed to 1800 rpm and stir for 20 minutes to obtain the conductive coating.

[0145] The scanning electron microscope image of the highly conductive graphene in Example 1 is shown below. Figure 5 .

[0146] Digital photos of conductive coatings can be found Figure 6 This indicates that the carbon-based conductive material is uniformly dispersed and does not float.

[0147] Scanning electron microscope image of conductive coating is shown below Figure 7 This indicates that the graphene is evenly dispersed and forms a conductive network.

[0148] The adhesion test result of the conductive coating film is grade 1. The volume resistivity of the conductive coating is 0.5 Ω·m. The film hardness of the conductive coating is 2H.

[0149] Example 2

[0150] 1) Mix 7 parts of conductive graphene (99.2% carbon content, 945 S / cm conductivity, ID / IG = 0.46), 50 parts of water, and 0.05 parts of dispersant A2 until they are uniformly mixed. Add the mixed material to a grinder and grind until D50 < 2 μm to obtain a slurry.

[0151] 2) Add 0.5 parts of polyurethane resin and 0.5 parts of 1,2-propanediol to the slurry and stir in a mixer; adjust the mixer speed to 1700 rpm and stir for 25 minutes to obtain the conductive coating. In the conductive coating, the carbon-based conductive material is uniformly dispersed and there is no floating phenomenon.

[0152] The adhesion test result of the conductive coating film is level 2. The volume resistivity of the conductive coating is 0.3 Ω·m. The film hardness of the conductive coating is 3H.

[0153] Example 3

[0154] 1) Mix 4 parts of conductive graphene (99.7% carbon content, 1358 S / m conductivity, ID / IG = 0.46), 10 parts of water, and 0.01 parts of dispersant A3 until they are uniformly mixed. Add the mixed material to a grinder and grind until D50 < 2 μm to obtain a slurry.

[0155] 2) Add 4 parts of acrylic resin and 0.05 parts of 1,3-propanediol to the slurry and stir in a mixer; adjust the mixer speed to 1800 rpm and stir for 30 minutes to obtain the conductive coating. In the conductive coating, the carbon-based conductive material is evenly dispersed and there is no floating phenomenon.

[0156] The adhesion test result of the conductive coating film is level 2. The volume resistivity of the conductive coating is 0.2 Ω·m. The film hardness of the conductive coating film is 6H.

[0157] Example 4

[0158] 1) Mix 2 parts of conductive graphene (99.2% carbon content, 945 S / cm conductivity, ID / IG = 0.46), 50 parts of water, and 1 part of dispersant A6 until they are initially homogeneous; then grind the initially mixed material in a grinder until D50 < 2 μm to obtain a slurry.

[0159] 2) Add 0.5 parts of polyurethane resin and 1 part of glycerol to the slurry, and stir in a mixer; adjust the mixer speed to 1700 rpm and stir for 25 minutes to obtain the conductive coating. In the conductive coating, the carbon-based conductive material is evenly dispersed and there is no floating phenomenon.

[0160] The adhesion test result of the conductive coating film is level 2. The volume resistivity of the conductive coating is 0.4 Ω·m. The film hardness of the conductive coating film is 4H.

[0161] Example 5

[0162] The method of Example 1 was followed, except that the dispersant was A4, and all other conditions were the same as in Example 1. In the prepared conductive coating, the carbon-based conductive material was uniformly dispersed without any floating phenomenon.

[0163] The adhesion test result of the prepared conductive coating film was grade 3. The volume resistivity of the conductive coating was 1 Ω·m. The film hardness of the conductive coating was 2H.

[0164] Example 6

[0165] The method of Example 1 was followed, except that the dispersant was A5, and the other conditions were the same as in Example 1. In the prepared conductive coating, the carbon-based conductive material was uniformly dispersed without any floating phenomenon.

[0166] The adhesion test result of the prepared conductive coating film was grade 3. The volume resistivity of the conductive coating was 0.8 Ω·m. The film hardness of the conductive coating was 2H.

[0167] Comparative Example 1

[0168] Following the method in Preparation Example 1, the difference is that the product obtained in step (2) was subjected to methyl-terminal capping with chloromethane at 60°C. After the reaction reached a stable pressure, heating was stopped, and the mixture was neutralized with phosphoric acid solution. After filtration and dehydration, a product with a methyl terminator was obtained, which is the dispersant DA1, with the structure shown in the following formula:

[0169]

[0170] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 48.24 mN / m; the dynamic surface tension is 43.58 mN / m.

[0171] The contact angle of the dispersant on commercial monocrystalline silicon wafers was tested using a contact angle meter. The contact angle of dispersant DA2 on the solid silicon wafer was 65.8°.

[0172] Following the method of Example 1, an equal amount of dispersant DA1 was used to replace dispersant A1 in Example 1, and the other conditions were the same as in Example 1.

[0173] The adhesion test result of the prepared conductive coating film was grade 4. The volume resistivity of the conductive coating was 3.1 Ω·m. The film hardness of the conductive coating was 1H.

[0174] Comparative Example 2

[0175] Following the method of Preparation Example 1, except that an equal amount of 1-pentanol was used to replace 3,5,5-trimethyl-1-hexanol. Dispersant DA2 was obtained, with the structure shown in formula (1), wherein R is -CH2CH2CH2CH2CH3, m:n = 2:1, m = 8, n = 4, and M = 670 g / mol.

[0176] The dispersant is mixed with water to obtain an aqueous solution of the dispersant. The mass concentration of the dispersant is 0.1%, and the static surface tension of the aqueous solution of the dispersant is 43.56 mN / m; the dynamic surface tension is 54.52 mN / m.

[0177] The contact angle of the dispersant on commercial monocrystalline silicon wafers was tested using a contact angle meter. The contact angle of dispersant DA3 on the solid silicon wafer was 76.3°.

[0178] Following the method of Example 1, an equal amount of dispersant DA2 was used to replace dispersant A1 in Example 1, and the other conditions were the same as in Example 1.

[0179] The adhesion test result of the prepared conductive coating film was grade 5. The volume resistivity of the conductive coating was 2.4 Ω·m. The film hardness of the conductive coating was 1H.

[0180] Comparative Example 3

[0181] The method is the same as in Example 1, except that an equal amount of dispersant C is used. 12 H 25 N(C2H5)3Cl was used to replace dispersant A1 in Example 1, and the other conditions were the same as in Example 1.

[0182] The adhesion test result of the prepared conductive coating film was grade 5. The volume resistivity of the conductive coating was 2.6 Ω·m. The film hardness of the conductive coating was 1H.

[0183] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A conductive coating, characterized in that, The conductive coating comprises: carbon-based conductive material, dispersant, additives, solvent, and resin; The dispersant comprises at least one of block polyether dispersants, the block polyether dispersant having the structure shown in formula (1): Equation (1), Wherein, the ratio of m to n is 0.3-3:1; the weight-average molecular weight of the block polyether dispersant does not exceed 2000 g / mol; R is selected from -CH2CH2CH(CH3)CH2C(CH3)2CH3, -C(CH2CH3)(CH2CH2CH3)CH3, -CH2CH2C(CH3)2CH2CH3 or -C(CH3)2CH2CH3; The carbon-based conductive material is graphene.

2. The conductive coating according to claim 1, wherein, The ratio of m to n is 0.5-2:1; m is 1-14, and n is 1-14.

3. The conductive coating according to claim 1, wherein, m is 3-9, n is 3-9; The weight-average molecular weight of the block polyether dispersant is 450-1500 g / mol.

4. The conductive coating according to any one of claims 1-3, wherein, The block polyether dispersant was mixed with water to obtain an aqueous solution with a mass concentration of 0.1%, and the static surface tension of the aqueous solution was 23-40 mN / m. The dynamic surface tension of the aqueous solution is 25-42 mN / m.

5. The conductive coating according to claim 4, wherein, The block polyether dispersant was mixed with water to obtain an aqueous solution with a mass concentration of 0.1%, and the static surface tension of the aqueous solution was 25-30 mN / m. The dynamic surface tension of the aqueous solution is 27-40 mN / m.

6. The conductive coating according to any one of claims 1-3, wherein, The contact angle of the block polyether dispersant with the solid silicon wafer is less than 80°.

7. The conductive coating according to claim 6, wherein, The block polyether dispersant has a contact angle of 20-50° with the solid silicon wafer.

8. The conductive coating according to any one of claims 1-3, wherein, The block polyether dispersant is selected from at least one of (CH3)3CCH2CH(CH3)CH2CH2O(C2H4O)3(C3H6O)3H, CH3(CH2CH2CH3)(CH2CH3)CO(C2H4O)3(C3H6O)6H, CH3CH2C(CH3)2CH2CH2O(C2H4O)8(C3H6O)4H, and CH3CH2(CH3)2CO(C2H4O)4(C3H6O)8H.

9. The conductive coating according to claim 8, wherein, The block polyether dispersant is (CH3)3CCH2CH(CH3)CH2CH2O(C2H4O)3(C3H6O)3H.

10. The conductive coating according to any one of claims 1-3, wherein, The conductive coating contains, by weight, the following: 1-10 parts by weight of carbon-based conductive material, 0.01-2 parts by weight of dispersant, and 0.01-4 parts by weight of resin. Additives: 0.01-1 parts by weight; solvents: 10-100 parts by weight.

11. The conductive coating according to any one of claims 1-3, wherein, The resin is selected from at least one of polyurethane resin, acrylic resin, epoxy resin and polyether resin.

12. The conductive coating according to any one of claims 1-3, wherein, The additive is at least one of ethylene glycol, 1,2-propanediol, 1,3-propanediol and glycerol.

13. The conductive coating according to any one of claims 1-3, wherein, Carbon-based conductive materials have a D50 of < 2 μm.

14. The conductive coating according to any one of claims 1-3, wherein, The solvent is water.

15. The conductive coating according to claim 11, wherein, The resin is selected as epoxy resin.

16. The conductive coating according to claim 12, wherein, The additive is ethylene glycol.

17. The conductive coating according to any one of claims 1-3, wherein, The graphene is selected from powdered graphene, which has a three-dimensional structure and is an accumulation of graphene sheets. The properties of the powdered graphene are as follows: it has D and G peaks in the Raman spectrum, ID / IG is below 0.10, and electrical conductivity is 500-5000 S / cm.

18. A method for preparing the conductive coating according to any one of claims 1-17, characterized in that, The method includes: (1) Mix carbon-based conductive material, solvent, and dispersant, and grind to obtain a slurry; (2) Mix the slurry with resin and additives and stir to obtain a coating.

19. The preparation method according to claim 18, wherein, In step (2), the stirring speed is 1500-2000 rpm and the stirring time is 10-30 min.

20. The application of the conductive coating according to any one of claims 1-17 in screen printing.

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