Shielding coating and preparation method thereof

Abstract

This invention relates to the field of shielding coating technology, and more particularly to a shielding coating and its preparation method. The shielding coating is composed of the following raw materials in parts by weight: 30-40 parts coating resin, 5-15 parts magnetic porous conductive powder, 6-8 parts curing agent, 1-3 parts coupling agent, 0.3-0.6 parts modified polyurethane block copolymer dispersant, 0.05-0.2 parts coating drying agent, 10-15 parts solvent, 0.8-2 parts terminal amine polyol ester, and 2-4 parts sodium glycerophosphate. The shielding coating proposed in this invention incorporates magnetic porous conductive powder, which contains nano-ferric oxide. The nano-ferric oxide attracts each other, resulting in small gaps between the magnetic porous conductive powder particles. After curing, the magnetic porous conductive powder particles form a dense film, effectively ensuring the shielding effect of the coating.

Description

Technical Field

[0001] The present invention relates to the technical field of shielding coatings, and in particular to a shielding coating and a preparation method thereof. Background Art

[0002] With the rapid development of the electronic information industry, communication equipment and electronic products are becoming more and more popular, and the interference of electromagnetic waves is becoming more and more serious. This is because electric and magnetic fields are generated during the operation of electronic and electrical equipment. The dense configuration and its equipment will cause cross-radiation of electromagnetic waves, which will cause radiation pollution. They are also very susceptible to external electromagnetic interference, which seriously affects the operation of electronic and electrical equipment and causes errors in their instruments or equipment. Therefore, electromagnetic shielding coatings with excellent shielding performance and simple manufacturing process have become a hot topic in research.

[0003] The existing electromagnetic shielding coatings are mainly conductive coatings. The conductive fillers added to the conductive coatings are generally metal powders such as gold, silver, copper, nickel, and non-metal powders such as carbon black and graphite. Gold powder and silver powder have the highest conductivity and good chemical stability, but they are expensive, so their use is limited. Carbon black and graphite powders are conductive fillers with good dispersibility and low price, but poor conductivity. Therefore, we propose a shielding coating and a preparation method thereof to solve the above problems.

[0004] Therefore, we propose a shielding coating and a preparation method thereof to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a shielding coating and a preparation method thereof.

[0006] A shielding coating is composed of the following raw materials in parts by weight: 30-40 parts of coating resin, 5-15 parts of magnetic porous conductive powder, 6-8 parts of curing agent, 1-3 parts of coupling agent, 0.3-0.6 parts of modified polyurethane block copolymer dispersant, 0.05-0.2 parts of coating drier, 10-15 parts of solvent, 0.8-2 parts of terminal amine polyol ester and 2-4 parts of sodium glycerophosphate.

[0007] Preferably, the preparation method of the magnetic porous conductive powder comprises the following steps: adding glucose, ferric chloride and sodium hexametaphosphate to deionized water, adjusting the pH of the solution to 11 by sodium hydroxide, stirring for 20-30 minutes, and then placing the mixed solution in a sealed high-pressure reactor, keeping it warm at 160-180°C for 12-18 hours, after the high-pressure reactor is cooled to room temperature, filtering and washing the mixture in the reactor, collecting the filter cake, and drying it at 60-80°C for 6-12 hours to obtain nano iron oxide / porous carbon particles; immersing the nano iron oxide / porous carbon particles in a silver nitrate solution for 6-12 hours, and after drying, high-temperature reducing the nano iron oxide / porous carbon particles immersed in silver nitrate, and heat treating them at 300-320°C for 6-8 hours in an N2 / H2 atmosphere with H2 accounting for 8% by volume to obtain silver / nano ferroferric oxide / porous carbon particles, i.e., magnetic porous conductive powder.

[0008] Preferably, the mass ratio of ferric chloride to deionized water is 0.005-0.02:1, the mass ratio of glucose to ferric chloride is 2-5:1, and the mass ratio of sodium hexametaphosphate to ferric chloride is 0.05-0.2:1.

[0009] Preferably, the concentration of the silver nitrate solution is 0.05 mol / L-0.3 mol / L.

[0010] Preferably, during the preparation of the magnetic porous conductive powder, after high-temperature reduction, the magnetic porous conductive powder is sieved so that the particle size distribution of the magnetic porous conductive powder is 300-2000 nm.

[0011] Preferably, the coating resin is selected from at least one of epoxy resin, polyurethane resin, polyester polyol, polyimide, and long-chain branched hydroxy acrylic resin.

[0012] Preferably, the solvent is selected from at least one of propylene glycol methyl ether acetate, xylene, n-butanol, butyl acetate, methyl isobutyl ketone and cyclohexanone.

[0013] Preferably, the coupling agent is a silane coupling agent, and the silane coupling agent is at least one of KH-560, A-171, YDH-151 and KH-550, and the coating drying agent is T12 dibutyltin dilaurate.

[0014] Preferably, the curing agent is selected from at least one of polyamide, phenalkamine, polyetheramine and polyisocyanate.

[0015] Preferably, a method for preparing a shielding coating comprises the following steps:

[0016] Step 1, weighing by weight: magnetic porous conductive powder, coupling agent, amine-terminated polyol ester and sodium glycerophosphate and mixing them thoroughly;

[0017] Step 2, weighing by weight: coating resin, solvent and modified polyurethane block copolymer dispersant, mixing evenly with the mixture in step 1, stirring for 1-2 hours at room temperature with a high-speed disperser to obtain shielding coating component A;

[0018] Step 3, dilute the curing agent and the drying agent with a solvent according to a certain ratio to a specified solid content of 50%-60%, which is the B component of the shielding coating;

[0019] Step 4: When using, adjust the ratio of component A to component B in a ratio of 4-6:1, mix well, and let it stand for 0.5h before use.

[0020] The beneficial effects of the present invention are:

[0021] 1. The shielding coating proposed in the present invention has magnetic porous conductive powder added therein. The magnetic porous conductive powder contains nano-ferroferric oxide. The nano-ferroferric oxide attracts each other, which makes the gaps between the magnetic porous conductive powders small. After the shielding coating is cured, a dense film can be formed between the magnetic porous conductive powders, which effectively ensures the shielding effect of the coating.

[0022] 2. The shielding coating proposed in the present invention has magnetic porous conductive powder added therein. A small amount of silver particles are used to improve the conductive properties of porous carbon particles in the magnetic porous conductive powder. Compared with directly adding metallic silver powder to the coating, the cost is greatly reduced and the shielding effect is good.

[0023] 3. The shielding coating proposed in the present invention adds a small amount of terminal amine polyol ester and sodium glycerol phosphate, which can improve the antioxidant properties of the coating. The terminal amine polyol ester and sodium glycerol phosphate can modify the magnetic porous conductive powder. Sodium glycerol phosphate also has certain lubricating properties, so that the modified magnetic porous conductive powder can be smoothly aggregated to form a dense shielding layer inside the coating of the coating. DETAILED DESCRIPTION

[0024] The present invention will be further explained below in conjunction with specific embodiments.

[0025] In the following embodiments, the experimental methods or test methods, unless otherwise specified, are conventional methods; reagents and materials, unless otherwise specified, are obtained from conventional commercial channels or prepared by conventional methods, wherein: coating resins, dispersants and driers were purchased from Shanghai Kain Chemical, Guangzhou Haoyi New Materials Co., Ltd., and Wuxi Qianguang Chemical Raw Materials Co., Ltd.; the terminal amine polyol ester is JL-G02FX type terminal amine polyol ester, purchased from Jiangsu Xinsu New Materials Co., Ltd.; the coupling agent is a silane coupling agent, purchased from Jiangsu Caiwei Biotechnology Co., Ltd.; sodium glycerophosphate was purchased from Jiangsu Pules Biotechnology Co., Ltd.; ferric chloride and sodium hexametaphosphate were purchased from Jiangsu Jiujia Biotechnology Co., Ltd.; glucose was purchased from Suzhou Zhanqing Environmental Protection Technology Co., Ltd.

[0026] In Example 1, a shielding coating is composed of the following raw materials in parts by weight: 30 parts of coating resin, 5 parts of magnetic porous conductive powder, 6 parts of curing agent, 1 part of coupling agent, 0.3 parts of modified polyurethane block copolymer dispersant, 0.05 parts of coating drying agent, 10 parts of solvent, 0.8 parts of terminal amino polyol ester and 2 parts of sodium glycerol phosphate.

[0027] The preparation method of magnetic porous conductive powder comprises the following steps: adding glucose, ferric chloride and sodium hexametaphosphate into deionized water, adjusting the pH value of the solution to 11 by sodium hydroxide, stirring for 20 minutes, then placing the mixed solution in a sealed high-pressure reactor, keeping the temperature at 160 DEG C for 12 hours, filtering and washing the mixture in the reactor after the high-pressure reactor is cooled to room temperature, collecting the filter cake, and drying at 60 DEG C for 6 hours to obtain nano iron oxide / porous carbon particles; immersing the nano iron oxide / porous carbon particles in a silver nitrate solution for 6 hours, drying, and then high-temperature reducing the nano iron oxide / porous carbon particles immersed in silver nitrate, and heat treating at 300 DEG C for 6 hours in an N2 / H2 atmosphere with H2 accounting for 8% by volume to obtain silver / nano ferroferric oxide / porous carbon particles, i.e., magnetic porous conductive powder.

[0028] The mass ratio of ferric chloride to deionized water is 0.005:1, the mass ratio of glucose to ferric chloride is 2:1, and the mass ratio of sodium hexametaphosphate to ferric chloride is 0.05:1.

[0029] The concentration of the silver nitrate solution is 0.05 mol / L.

[0030] In the preparation process of the magnetic porous conductive powder, after high-temperature reduction, the magnetic porous conductive powder is sieved so that the particle size distribution of the magnetic porous conductive powder is 300-2000nm.

[0031] The coating resin is selected from epoxy resin.

[0032] The solvent is selected from xylene.

[0033] The coupling agent is a silane coupling agent, and the silane coupling agent is KH-560.

[0034] The curing agent is selected from polyamide.

[0035] A method for preparing a shielding coating comprises the following steps:

[0036] Step 1, weighing by weight: magnetic porous conductive powder, coupling agent, amine-terminated polyol ester and sodium glycerophosphate and mixing them thoroughly;

[0037] Step 2, weighing by weight: coating resin, solvent and modified polyurethane block copolymer dispersant, and mixing them evenly with the mixture in step 1, stirring for 1 hour with a high-speed disperser at room temperature to obtain shielding coating component A;

[0038] Step 3, diluting the curing agent and the drying agent with a solvent to a specified solid content, such as 50%, according to a certain ratio, which is the B component of the shielding coating;

[0039] Wait for step 4, when using, mix component A and component B in a ratio of 4:1, let it stand for 0.5 hours and it can be used. The activation period of this coating is 4 hours.

[0040] In Example 2, a shielding coating is composed of the following raw materials in parts by weight: 40 parts of coating resin, 15 parts of magnetic porous conductive powder, 7 parts of curing agent, 0.6 parts of modified polyurethane block copolymer dispersant, 0.2 parts of coating drying agent, 15 parts of solvent, and 4 parts of sodium glycerophosphate.

[0041] The preparation method of magnetic porous conductive powder comprises the following steps: adding glucose, ferric chloride and sodium hexametaphosphate into deionized water, adjusting the pH value of the solution to 11 by sodium hydroxide, stirring for 30 minutes, then placing the mixed solution in a sealed high-pressure reactor, keeping the temperature at 180 DEG C for 18 hours, filtering and washing the mixture in the reactor after the high-pressure reactor is cooled to room temperature, collecting the filter cake, and drying at 80 DEG C for 12 hours to obtain nano iron oxide / porous carbon particles; immersing the nano iron oxide / porous carbon particles in a silver nitrate solution for 12 hours, drying, and then high-temperature reducing the nano iron oxide / porous carbon particles immersed in silver nitrate, and heat treating at 320 DEG C for 8 hours in an N2 / H2 atmosphere with H2 accounting for 8% by volume to obtain silver / nano ferroferric oxide / porous carbon particles, i.e., magnetic porous conductive powder.

[0042] The mass ratio of ferric chloride to deionized water is 0.02:1, the mass ratio of glucose to ferric chloride is 5:1, and the mass ratio of sodium hexametaphosphate to ferric chloride is 0.2:1.

[0043] The concentration of silver nitrate solution is 0.3 mol / L.

[0044] In the preparation process of the magnetic porous conductive powder, after high-temperature reduction, the magnetic porous conductive powder is sieved so that the particle size distribution of the magnetic porous conductive powder is 300-2000nm.

[0045] The coating resin is selected from polyester polyols.

[0046] The solvent is selected from a mixture of propylene glycol methyl ether acetate and xylene in a ratio of 1:1.

[0047] The drying agent is dibutyltin dilaurate.

[0048] The curing agent is selected from HDI trimer such as N3390.

[0049] A method for preparing a shielding coating comprises the following steps:

[0050] Step 1, weighing by weight: magnetic porous conductive powder, coupling agent, amine-terminated polyol ester and sodium glycerophosphate and mixing them thoroughly;

[0051] Step 2, weighing the coating resin and solvent in parts by weight, mixing them evenly with the mixture in step 1, and stirring them for 2 hours with a high-speed disperser at room temperature to obtain component A of the shielding coating;

[0052] Step 3, dilute the curing agent and the drying agent with a solvent according to a certain ratio to a specified solid content, the solid content is 60%, which is the B component of the shielding coating;

[0053] Step 4: Mix component A and component B in a ratio of 6:1, stir thoroughly and let stand for 0.5h before use.

[0054] In Example 3, a shielding coating is composed of the following raw materials in parts by weight: 35 parts of coating resin, 10 parts of magnetic porous conductive powder, 5 parts of curing agent, 0.5 parts of modified polyurethane block copolymer dispersant, 0.1 parts of coating drying agent, 12 parts of solvent, and 3 parts of sodium glycerophosphate.

[0055] The preparation method of magnetic porous conductive powder comprises the following steps: adding glucose, ferric chloride and sodium hexametaphosphate into deionized water, adjusting the pH value of the solution to 11 by sodium hydroxide, stirring for 25 minutes, then placing the mixed solution in a sealed high-pressure reactor, keeping the temperature at 160-180 DEG C for 16 hours, filtering and washing the mixture in the reactor after the high-pressure reactor is cooled to room temperature, collecting the filter cake, and drying at 70 DEG C for 10 hours to obtain nano iron oxide / porous carbon particles; immersing the nano iron oxide / porous carbon particles in a silver nitrate solution for 10 hours, drying, and then high-temperature reducing the nano iron oxide / porous carbon particles immersed in silver nitrate, and heat treating at 310 DEG C for 6.5 hours in an N2 / H2 atmosphere in which the volume of H2 accounts for 8%, to obtain silver / nano ferroferric oxide / porous carbon particles, namely magnetic porous conductive powder.

[0056] The mass ratio of ferric chloride to deionized water is 0.01:1, the mass ratio of glucose to ferric chloride is 3:1, and the mass ratio of sodium hexametaphosphate to ferric chloride is 0.01:1.

[0057] The concentration of silver nitrate solution is 0.2 mol / L.

[0058] In the preparation process of the magnetic porous conductive powder, after high-temperature reduction, the magnetic porous conductive powder is sieved so that the particle size distribution of the magnetic porous conductive powder is 300-2000nm.

[0059] The coating resin is selected from long-chain branched hydroxy acrylic resin.

[0060] The solvent is selected from a mixture of propylene glycol methyl ether acetate and xylene in a ratio of 1:1.

[0061] The drying agent is dibutyltin dilaurate.

[0062] The curing agent is selected from HDI trimer such as N3390.

[0063] A method for preparing a shielding coating comprises the following steps:

[0064] Step 1, weighing by weight: magnetic porous conductive powder, coupling agent, amine-terminated polyol ester and sodium glycerophosphate and mixing them thoroughly;

[0065] Step 2, weighing the coating resin and solvent in parts by weight, mixing them evenly with the mixture in step 1, and stirring them for 1.5 hours with a high-speed disperser at room temperature to obtain component A of the shielding coating;

[0066] Step 3, dilute the curing agent and the drying agent with a solvent according to a certain ratio to a specified solid content, the solid content is 55%, which is the B component of the shielding coating;

[0067] Step 4: When using, mix component A and component B in a ratio of 5:1, stir thoroughly, and let it stand for 0.5h before use.

[0068] In Examples 1-3, the coating resin is selected from at least one of epoxy resin, polyurethane resin, polyester polyol, polyimide, and long-chain branched hydroxy acrylic resin.

[0069] The solvent is selected from at least one of propylene glycol methyl ether acetate, xylene, n-butanol, butyl acetate, methyl isobutyl ketone and cyclohexanone.

[0070] The coupling agent is a silane coupling agent, and the silane coupling agent is at least one of KH-560, A-171, YDH-151 and KH-550; the drying agent is T12 dibutyltin dilaurate.

[0071] The curing agent is selected from at least one of polyamide, phenalkamine, polyetheramine and polyisocyanate.

[0072] In Comparative Example 1, compared with Example 1, in Comparative Example 1, no magnetic porous conductive powder is added, and the rest is the same as Example 1.

[0073] In Comparative Example 2, compared with Example 1, in Comparative Example 2, when preparing the magnetic porous conductive powder, the powder was not immersed in the silver nitrate solution, and the rest was the same as Example 1.

[0074] In Comparative Example 3, compared with Example 1, in Comparative Example 3, ferric chloride was not added when preparing the magnetic porous conductive powder, and the rest was the same as Example 1.

[0075] In Comparative Example 4, compared with Example 1, in Comparative Example 4, no amine-terminated polyol ester was added, and the rest was the same as Example 1.

[0076] In Comparative Example 5, compared with Example 1, in Comparative Example 5, sodium glycerophosphate was not added, and the rest was the same as Example 1.

[0077] The coatings prepared in Examples 1-3 and Comparative Examples 1-5 were applied to the panels respectively to obtain eight groups of panels with shielding coatings corresponding to Examples 1-3 and Comparative Examples 1-5. The electromagnetic shielding efficiency of the above five groups of panels was tested according to the method of national standard GBT34938-2017, and the test results are shown in Table 1.

[0078] Table 1

[0079] Electromagnetic shielding efficiency (dB) Example 1 67 Example 2 75 Example 3 71 Comparative Example 1 7 Comparative Example 2 32 Comparative Example 3 49 Comparative Example 4 68 Comparative Example 5 54

[0080] As can be seen from Table 1, in Examples 1-3, the prepared shielding coatings have good electromagnetic shielding effects; in Comparative Example 1, compared with Example 1, no magnetic porous conductive powder was added, and it had almost no shielding effect; in Comparative Example 2, compared with Example 1, when preparing the magnetic porous conductive powder, it was not immersed in a silver nitrate solution, that is, the prepared magnetic porous conductive powder did not contain silver, and its shielding effect was average; in Comparative Example 3, compared with Example 1, when preparing the magnetic porous conductive powder, no ferric chloride was added, that is, the prepared porous conductive powder did not contain magnetism, and its shielding effect was not as good as that of Examples 1-3; in Comparative Example 4, compared with Example 1, no terminal amino polyol ester was added, and its shielding effect was close to that of Example 1; in Comparative Example 5, compared with Example 1, no sodium glycerophosphate was added, and its shielding effect was slightly lower than that of Example 1.

[0081] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A shielding coating, characterized in that: The invention is composed of the following raw materials in parts by weight: 30-40 parts of coating resin, 5-15 parts of magnetic porous conductive powder, 6-8 parts of curing agent, 1-3 parts of coupling agent, 0.3-0.6 parts of modified polyurethane block copolymer dispersant, 0.05-0.2 parts of coating drier, 10-15 parts of solvent, 0.8-2 parts of terminal amine polyol ester and 2-4 parts of sodium glycerophosphate; The preparation method of the magnetic porous conductive powder comprises the following steps: adding glucose, ferric chloride and sodium hexametaphosphate to deionized water, adjusting the pH value of the solution to 11 by sodium hydroxide, stirring for 20-30 minutes, then placing the mixed solution in a sealed high-pressure reactor, keeping it warm at 160-180° C. for 12-18 hours, filtering and washing the mixture in the reactor after the high-pressure reactor is cooled to room temperature, collecting the filter cake, and drying it at 60-80° C. for 6-12 hours to obtain nano iron oxide / porous carbon particles; immersing the nano iron oxide / porous carbon particles in a silver nitrate solution for 6-12 hours, and after drying, high-temperature reducing the nano iron oxide / porous carbon particles immersed in silver nitrate, and heat treating them at 300-320° C. for 6-8 hours in an N2 / H2 atmosphere in which H2 accounts for 8% by volume to obtain silver / nano ferroferric oxide / porous carbon particles, namely, magnetic porous conductive powder.

2. A shielding coating according to claim 1, characterized in that: The mass ratio of the ferric chloride to deionized water is 0.005-0.02:1, the mass ratio of glucose to ferric chloride is 2-5:1, and the mass ratio of sodium hexametaphosphate to ferric chloride is 0.05-0.2:

1.

3. The shielding coating according to claim 1, characterized in that: The concentration of the silver nitrate solution is 0.05 mol / L-0.3 mol / L.

4. The shielding coating according to claim 1, characterized in that: In the preparation process of the magnetic porous conductive powder, after high-temperature reduction, the magnetic porous conductive powder is sieved so that the particle size distribution of the magnetic porous conductive powder is 300-2000nm.

5. The shielding coating according to claim 1, characterized in that: The coating resin is selected from at least one of epoxy resin, polyurethane resin, polyester polyol, polyimide, and long-chain branched hydroxy acrylic resin.

6. The shielding coating according to claim 1, characterized in that: The solvent is selected from at least one of propylene glycol methyl ether acetate, xylene, n-butanol, butyl acetate, methyl isobutyl ketone and cyclohexanone.

7. The shielding coating according to claim 1, characterized in that: The coupling agent is a silane coupling agent, and the silane coupling agent is at least one of KH-560, A-171, YDH-151 and KH-550. The coating drying agent is T12 dibutyltin dilaurate.

8. The shielding coating according to claim 1, characterized in that: The curing agent is selected from at least one of polyamide, phenalkamine, polyetheramine and polyisocyanate.

9. A method for preparing the shielding coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1, weighing by weight: magnetic porous conductive powder, coupling agent, amine-terminated polyol ester and sodium glycerophosphate and mixing them thoroughly; Step 2, weighing by weight: coating resin, solvent and modified polyurethane block copolymer dispersant, mixing evenly with the mixture in step 1, stirring for 1-2 hours at room temperature with a high-speed disperser to obtain shielding coating component A; Step 3: Dilute the curing agent and the drying agent with a solvent in a certain proportion to a specified solid content of 50%-60%, which is the B component of the shielding coating; Step 4: Mix component A and component B in a ratio of 4-6:1, stir thoroughly and let stand for 0.5h before use.