Electromagnetic shielding interior wall paint and method for preparing the same

Abstract

The present application relates to the technical field of electromagnetic shielding coating, in particular to an electromagnetic shielding interior wall coating and a preparation method thereof, the electromagnetic shielding coating adopts a graphene-crosslinking polymer composite material and a plated nickel zinc oxide whisker composite system, dopamine rich in amino groups is grafted to polyacrylic acid rich in carboxyl groups through amidation reaction, and dopamine occurs self-polymerization reaction, a physical and chemical double-crosslinked conductive polymer network is formed in the drying process, and the conductivity problem of graphene as a conductive filler is improved; meanwhile, plated nickel zinc oxide whiskers are added in the coating, and due to the bridging effect of the fibrous whiskers, the compactness and integrity of the three-dimensional conductive network skeleton in the coating are improved, under the action of electromagnetic waves, the concentration of carriers increases, the migration channels increase, and the conductivity of the coating is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electromagnetic shielding coating, in particular to an electromagnetic shielding interior wall coating and a preparation method thereof. BACKGROUND

[0002] At present, with the rapid development of electronic industry and information industry, communication equipment and various electronic products are increasingly popular. However, electronic and electrical equipment also produces electromagnetic radiation, causing radiation pollution, and is also extremely susceptible to external electromagnetic interference, bringing serious interference and influence to the operation of electronic and electrical equipment; and electromagnetic waves can also cause damage to the human body, so various effective protection measures must be taken. Therefore, electromagnetic shielding coatings with excellent shielding performance, simple construction process and the advantages of integration with equipment substrates, etc. are born, and are widely used in various electronic products, devices and systems as electromagnetic radiation protection. Electromagnetic shielding coatings use reflection, absorption and other properties of coatings to prevent electromagnetic energy generated by field sources from entering the shielded area, thereby effectively eliminating or reducing the interference and influence of the electromagnetic environment on the equipment and the harm to human health, and ensuring the coordinated and effective simultaneous operation of various equipment. Electromagnetic shielding coatings combine electromagnetic control technology with coating production process, and are favored by people due to their simple preparation, convenient construction and other advantages; their research is becoming more and more in-depth, and the types are becoming more and more, becoming one of the most widely used electromagnetic shielding materials at home and abroad, accounting for more than 70% of the entire shielding material.

[0003] The existing electromagnetic shielding coatings are mainly conductive coatings, and the conductive fillers added in the conductive coatings are generally metal powders such as gold, silver, copper and nickel, and non-metallic powders such as carbon black and graphite. Gold powder has the highest conductivity and good chemical stability, but the price is high, so that the use is limited. The conductivity of silver powder is also very good, and the price is lower than that of gold powder, and it is easy to migrate. The performance of copper and nickel is similar to that of silver, and the price is much lower than that of silver, but it is easy to oxidize, the conductivity is unstable, and the durability is poor. Therefore, to some extent, the popularization and application of silver and copper electromagnetic wave shielding coatings are limited. Carbon black and graphite powder as conductive fillers have good dispersibility and low price, but the conductivity is poor, and it is a relatively ideal material for electromagnetic shielding. SUMMARY

[0004] The technical problem to be solved by the present application is how to improve the conductivity of electromagnetic shielding coatings while reducing the production cost.

[0005] The electromagnetic shielding coating of the present application adopts a graphene-crosslinked polymer composite material and a nickel-plated zinc oxide whisker composite system, dopamine rich in amino groups is grafted to polyacrylic acid rich in carboxyl groups through an amidation reaction, and dopamine undergoes a self-polymerization reaction to form a physical and chemical double-crosslinked conductive polymer network during the drying process, thereby improving the poor conductivity problem of graphene as a conductive filler; meanwhile, nickel-plated zinc oxide whiskers are added to the coating, and due to the bridging effect of the fibrous whiskers, the compactness and integrity of the three-dimensional conductive network skeleton in the coating are improved, under the action of electromagnetic waves, the concentration of charge carriers increases and the migration channels increase, thereby further improving the conductivity of the coating.

[0006] To achieve the above object, the present application provides the following technical scheme: An electromagnetic shielding interior wall coating, by mass fraction, comprising the following components:

[0007] 30-40 parts of a base resin;

[0008] 10-30 parts of a filler;

[0009] 10-20 parts of nickel-plated zinc oxide whiskers;

[0010] 1-5 parts of a graphene-crosslinked polymer composite material;

[0011] 1-3 parts of a film-forming aid;

[0012] 0.1-1 parts of an aid;

[0013] 0.5-1.5 parts of a leveling agent;

[0014] 15-25 parts of a solvent.

[0015] Preferably, the base resin is an acrylic emulsion.

[0016] Preferably, the filler is a mixture of talc and titanium white, and the mass ratio of the talc and the titanium white is 1:2-3.

[0017] Preferably, the aid includes one or more of an antioxidant, a dispersant, a wetting agent, a defoaming agent, bentonite, and ethylene glycol.

[0018] Preferably, the solvent is water.

[0019] Preferably, the preparation method of the graphene-crosslinked polymer composite material comprises the following steps:

[0020] S1: dispersing polyacrylic acid and dopamine in N-methylpyrrolidone, mixing uniformly, then adding carboxyl nitrile rubber, and stirring to react to obtain a reaction liquid;

[0021] S2: filtering, concentrating, and vacuum drying the reaction liquid to obtain a crosslinked polymer composite material.

[0022] S3: adding the amino-functionalized graphene and the cross-linked polymer composite material above into N-methyl pyrrolidone and mixing uniformly to obtain a slurry, namely the graphene-cross-linked polymer composite material.

[0023] Preferably, the mass ratio of the polyacrylic acid, dopamine and carboxyl nitrile rubber in S1 is 1-3:1:1, the concentration of the polyacrylic acid is 0.01-0.03 g / ml, and the stirring reaction is carried out at a temperature of 100-150 DEG C for 10-15 h.

[0024] Preferably, the mass ratio of the amino-functionalized graphene and the cross-linked polymer composite material is 1:1-3.

[0025] Preferably, the preparation method of the coating comprises the following steps:

[0026] 1) adding a solvent, an additive, a filler, a nickel-coated zinc oxide whisker and the graphene-cross-linked polymer composite material into a reaction kettle and stirring uniformly;

[0027] 2) adding a base resin and a film-forming additive into the reaction kettle and stirring uniformly, and finally adding a leveling agent and stirring uniformly to obtain the electromagnetic shielding interior wall coating.

[0028] Preferably, the fineness of the mixture after the stirring in step 1) is less than 60 μm.

[0029] Compared with the prior art, the present application has the following beneficial effects:

[0030] (1) The graphene-cross-linked polymer composite material is used in the present application, dopamine rich in amino groups is grafted onto polyacrylic acid rich in carboxyl groups through an amidation reaction, and dopamine undergoes a self-polymerization reaction to form a physical-chemical double cross-linked conductive polymer network in the drying process, thereby improving the conductivity of the coating.

[0031] (2) Nickel-coated zinc oxide whiskers are added in the formula of the present application, and the bridging effect of the fibrous whiskers helps to improve the compactness and integrity of the three-dimensional conductive network skeleton in the coating, and under the action of electromagnetic waves, the concentration of carriers increases and the migration channels increase, thereby further improving the conductivity of the coating. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application. Embodiment 1

[0033] The components are prepared according to the following proportions: solvent (water) 15 parts, auxiliary 0.2 parts, filler 15 parts, nickel-plated zinc oxide whisker 10 parts, graphene-crosslinked polymer composite 2 parts, base resin (acrylic emulsion) 30 parts, film-forming aid 2 parts, leveling agent 1 part;

[0034] The preparation process of the filler is to take talcum powder and titanium dioxide according to a mass ratio of 1:2, mix uniformly to obtain the filler;

[0035] The preparation process of the auxiliary is: according to the mass parts of the components in the coating, take antioxidant 0.1 part, dispersant 0.5 part, wetting agent 0.1 part, defoamer 0.1 part, bentonite 0.1 part, ethylene glycol 0.5 part, mix uniformly to obtain the auxiliary;

[0036] The preparation process of the graphene-crosslinked polymer composite is: take polyacrylic acid, dopamine, and carboxyl nitrile rubber according to a mass ratio of 2:1:1, first mix polyacrylic acid and dopamine in N-methyl pyrrolidone uniformly, so that the concentration of polyacrylic acid is 0.02 g / ml, then add carboxyl nitrile rubber, mix at 150°C for 2h to obtain a suspension, stir the suspension at 100°C for 12h, then filter, rotary evaporate the filtrate to concentrate and vacuum dry at 115°C overnight to obtain the crosslinked polymer composite; take amino graphene and crosslinked polymer composite according to a mass ratio of 1:2, mix in N-methyl pyrrolidone to form a slurry, which is the graphene-crosslinked polymer composite.

[0037] Add the solvent (water), auxiliary, filler, nickel-plated zinc oxide whisker, and graphene-crosslinked polymer composite into the reaction kettle and stir uniformly; then add the base resin (acrylic emulsion) and film-forming aid into the reaction kettle and stir uniformly, finally add the leveling agent and stir uniformly to obtain the electromagnetic shielding interior wall coating. Example 2

[0038] The components are prepared according to the following proportions: solvent (water) 18 parts, auxiliary 0.3 parts, filler 18 parts, nickel-plated zinc oxide whisker 13 parts, graphene-crosslinked polymer composite 2 parts, base resin (acrylic emulsion) 33 parts, film-forming aid 2 parts, leveling agent 1 part;

[0039] The preparation process of the filler is to take talcum powder and titanium dioxide according to a mass ratio of 1:2, mix uniformly to obtain the filler;

[0040] The preparation process of the auxiliary is: according to the mass parts of the components in the coating, take antioxidant 0.1 part, dispersant 0.5 part, wetting agent 0.1 part, defoamer 0.1 part, bentonite 0.1 part, ethylene glycol 0.5 part, mix uniformly to obtain the auxiliary;

[0041] The preparation process of the graphene-crosslinked polymer composite material is as follows: polyacrylic acid, dopamine and carboxyl nitrile rubber are weighed according to a mass ratio of 1:1:1, polyacrylic acid and dopamine are first added into N-methyl pyrrolidone and uniformly mixed, so that the concentration of polyacrylic acid is 0.01 g / ml, then carboxyl nitrile rubber is added, and a suspension is obtained by mixing at 140°C for 2 hours; the suspension is stirred and reacted at 105°C for 10 hours, then filtered, the filtrate is concentrated by rotary evaporation and dried under vacuum at 115°C overnight to obtain the crosslinked polymer composite material; amino graphene and the crosslinked polymer composite material are weighed according to a mass ratio of 1:1, uniformly mixed in N-methyl pyrrolidone to form a slurry, and the graphene-crosslinked polymer composite material is obtained.

[0042] The solvent (water), the auxiliary agent, the filler, the nickel-plated zinc oxide whisker and the graphene-crosslinked polymer composite material are added into a reaction kettle and uniformly stirred; the base resin (acrylic emulsion) and the film-forming auxiliary agent are added into the reaction kettle and uniformly stirred, and finally the leveling agent is added and uniformly stirred to obtain the electromagnetic shielding interior wall coating. Example 3

[0043] The components are prepared according to the following proportions: solvent (water) 20 parts, auxiliary agent 0.3 parts, filler 21 parts, nickel-plated zinc oxide whisker 15 parts, graphene-crosslinked polymer composite material 3 parts, base resin (acrylic emulsion) 35 parts, film-forming auxiliary agent 2 parts, and leveling agent 1 part;

[0044] The preparation process of the filler is as follows: talcum powder and titanium white are weighed according to a mass ratio of 1:2, and uniformly mixed to obtain the filler.

[0045] The preparation process of the auxiliary agent is as follows: according to the mass parts of the components in the coating, antioxidant 0.1 part, dispersant 0.5 part, wetting agent 0.1 part, defoaming agent 0.1 part, bentonite 0.1 part and ethylene glycol 0.5 part are uniformly mixed to obtain the auxiliary agent.

[0046] The preparation process of the graphene-crosslinked polymer composite material is as follows: polyacrylic acid, dopamine and carboxyl nitrile rubber are weighed according to a mass ratio of 2:1:1, polyacrylic acid and dopamine are first added into N-methyl pyrrolidone and uniformly mixed, so that the concentration of polyacrylic acid is 0.03 g / ml, then carboxyl nitrile rubber is added, and a suspension is obtained by mixing at 145°C for 2 hours; the suspension is stirred and reacted at 100°C for 13 hours, then filtered, the filtrate is concentrated by rotary evaporation and dried under vacuum at 110°C overnight to obtain the crosslinked polymer composite material; amino graphene and the crosslinked polymer composite material are weighed according to a mass ratio of 1:2, uniformly mixed in N-methyl pyrrolidone to form a slurry, and the graphene-crosslinked polymer composite material is obtained.

[0047] The solvent (water), the auxiliary agent, the filler, the nickel-plated zinc oxide whisker, and the graphene-crosslinked polymer composite are added into a reaction kettle and stirred uniformly; the base resin (acrylic emulsion) and the film-forming aid are then added into the reaction kettle and stirred uniformly, and finally the leveling agent is added and stirred uniformly to obtain the electromagnetic shielding interior wall coating. Example 4

[0048] The components are prepared according to the following proportions: 23 parts of solvent (water), 0.5 parts of auxiliary agent, 28 parts of filler, 18 parts of nickel-plated zinc oxide whisker, 3 parts of graphene-crosslinked polymer composite, 38 parts of base resin (acrylic emulsion), 2 parts of film-forming aid, and 1 part of leveling agent.

[0049] The filler is prepared by mixing talcum powder and titanium dioxide in a mass ratio of 1:3.

[0050] The auxiliary agent is prepared by mixing 0.1 part of antioxidant, 0.5 part of dispersant, 0.1 part of wetting agent, 0.1 part of defoaming agent, 0.1 part of bentonite, and 0.5 part of ethylene glycol.

[0051] The graphene-crosslinked polymer composite is prepared by mixing polyacrylic acid, dopamine, and carboxyl nitrile rubber in a mass ratio of 1:1:1. The polyacrylic acid and dopamine are first mixed in N-methyl pyrrolidone to obtain a concentration of 0.01 g / ml, and then the carboxyl nitrile rubber is added and mixed at 135°C for 3 hours to obtain a suspension. The suspension is stirred at 105°C for 11 hours, filtered, concentrated by rotary evaporation, and dried under vacuum at 110°C overnight to obtain the crosslinked polymer composite. The amino graphene and the crosslinked polymer composite are mixed in a mass ratio of 1:1.5 in N-methyl pyrrolidone to form a slurry, which is the graphene-crosslinked polymer composite.

[0052] The solvent (water), the auxiliary agent, the filler, the nickel-plated zinc oxide whisker, and the graphene-crosslinked polymer composite are added into a reaction kettle and stirred uniformly; the base resin (acrylic emulsion) and the film-forming aid are then added into the reaction kettle and stirred uniformly, and finally the leveling agent is added and stirred uniformly to obtain the electromagnetic shielding interior wall coating. Example 5

[0053] The components are prepared according to the following proportions: 25 parts of solvent (water), 0.2 parts of auxiliary agent, 27 parts of filler, 20 parts of nickel-plated zinc oxide whisker, 4 parts of graphene-crosslinked polymer composite, 40 parts of base resin (acrylic emulsion), 2 parts of film-forming aid, and 1 part of leveling agent.

[0054] The filler is prepared by mixing talcum powder and titanium dioxide in a mass ratio of 1:2.5.

[0055] The preparation process of the auxiliary agent is as follows: according to the mass parts of components in the paint, 0.1 parts of antioxidant, 0.5 parts of dispersing agent, 0.1 parts of wetting agent, 0.1 parts of defoaming agent, 0.1 parts of bentonite and 0.5 parts of ethylene glycol are weighed and uniformly mixed to obtain the auxiliary agent;

[0056] The preparation process of the graphene-crosslinked polymer composite material is as follows: polyacrylic acid, dopamine and carboxyl nitrile rubber are weighed according to a mass ratio of 2.5:1:1, polyacrylic acid and dopamine are first added into N-methyl pyrrolidone and uniformly mixed to make the concentration of polyacrylic acid 0.02 g / ml, then carboxyl nitrile rubber is added, and a suspension is obtained by mixing at 145°C for 2 h; the suspension is stirred and reacted at 110°C for 11 h, then filtered, concentrated by rotary evaporation and vacuum dried at 120°C overnight to obtain the crosslinked polymer composite material; amino graphene and the crosslinked polymer composite material are weighed according to a mass ratio of 1:2.5, uniformly mixed in N-methyl pyrrolidone to form a slurry, and the graphene-crosslinked polymer composite material is obtained.

[0057] The solvent (water), auxiliary agent, filler, nickel-plated zinc oxide whisker and graphene-crosslinked polymer composite material are added into a reaction kettle and uniformly stirred; the base resin (acrylic emulsion) and film-forming auxiliary agent are added into the reaction kettle and uniformly stirred, and finally the leveling agent is added and uniformly stirred to obtain the electromagnetic shielding interior wall coating.

[0058] Comparative Example 1

[0059] The difference from Example 3 is that the graphene-crosslinked polymer composite material is not added in the formula, and only graphene is added;

[0060] The components are prepared according to the following proportions: solvent (water) 20 parts, auxiliary agent 0.3 parts, filler 21 parts, nickel-plated zinc oxide whisker 15 parts, graphene material 3 parts, base resin (acrylic emulsion) 35 parts, film-forming auxiliary agent 2 parts and leveling agent 1 part;

[0061] The preparation process of the filler is as follows: talcum powder and titanium white are weighed according to a mass ratio of 1:2, and uniformly mixed to obtain the filler;

[0062] The preparation process of the auxiliary agent is as follows: according to the mass parts of components in the paint, 0.1 parts of antioxidant, 0.5 parts of dispersing agent, 0.1 parts of wetting agent, 0.1 parts of defoaming agent, 0.1 parts of bentonite and 0.5 parts of ethylene glycol are weighed and uniformly mixed to obtain the auxiliary agent;

[0063] The preparation process of the graphene material is as follows: amino graphene is weighed and uniformly mixed in N-methyl pyrrolidone to form a slurry, and the graphene material is obtained.

[0064] The solvent (water), auxiliary agent, filler, nickel-plated zinc oxide whisker and graphene material are added into a reaction kettle and stirred uniformly; then the base resin (acrylic emulsion) and film-forming auxiliary agent are added into the reaction kettle and stirred uniformly, and finally the leveling agent is added and stirred uniformly, to obtain the electromagnetic shielding interior wall coating.

[0065] Performance test of the coating;

[0066] The coating of examples 1-5 and comparative example 1 is coated on a substrate plate with a coating thickness of 5 mm, and the coating area density is calculated after curing; the shielding effectiveness of the coating is tested by using a NA7500 type vector network analyzer according to the ASTM D4935-10 test standard; the conductivity of the coating is tested by using a four-probe method with a probe spacing of 1 mm; and the test results are shown in Table 1:

[0067] Table 1: Performance test results of the electromagnetic shielding interior wall coating

[0068]

[0069] As can be seen from Table 1, the coating area density of the electromagnetic shielding interior wall coating prepared by the present application is less than 50 g / m 2 , and has good shielding effectiveness and high conductivity; by comparing example 3 with comparative example 1, it is found that the shielding effectiveness and conductivity of the coating at 8GHz-12GHz are obviously better than those of comparative example 1, because in example 3, the graphene-crosslinked polymer composite material is used, the dopamine rich in amino groups is grafted to the polyacrylic acid rich in carboxyl groups through amidation reaction, and the dopamine undergoes self-polymerization reaction to form a physical and chemical double-crosslinked conductive polymer network in the drying process, thereby improving the poor conductivity problem of graphene as a conductive filler.

[0070] It is apparent for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and range of the equivalent elements of the claims are intended to be embraced in the present application, and any reference signs in the claims should not be considered as limiting the claims involved.

Claims

1. An electromagnetic shielding interior wall coating, characterized in that, By weight, it includes the following components: 30-40 parts of base resin; 10-30 parts of filler; 10-20 parts of nickel-plated zinc oxide whiskers; 1-5 parts of graphene-crosslinked polymer composite material; 1-3 parts of film-forming aid; Additives: 0.1-1 part; Leveling agent 0.5~1.5 parts; Solvent 15-25 parts; The preparation method of the graphene-crosslinked polymer composite material includes the following steps: S1: Disperse polyacrylic acid and dopamine in N-methylpyrrolidone, mix well, add carboxylated butadiene-acrylonitrile rubber, stir to react, and obtain reaction solution; S2: The reaction solution is filtered, concentrated, and vacuum dried to obtain a cross-linked polymer composite material; S3: Add N-methylpyrrolidone to the amino-graphene and the above cross-linked polymer composite material, mix evenly to obtain a slurry, which is the graphene-cross-linked polymer composite material; In step S1, the mass ratio of polyacrylic acid, dopamine, and carboxylated nitrile rubber is 1-3:1:1, the concentration of polyacrylic acid is 0.01-0.03 g / ml, and the stirring reaction is carried out at a temperature of 100-150°C for 10-15 hours. The mass ratio of the amino-graphene and cross-linked polymer composite material is 1:1~3.

2. The electromagnetic shielding interior wall coating according to claim 1, wherein the base resin is an acrylic emulsion.

3. The electromagnetic shielding interior wall coating according to claim 1, characterized in that, The filler is a mixture of talc and titanium dioxide, wherein the mass ratio of talc to titanium dioxide is 1:2~3.

4. The electromagnetic shielding interior wall coating according to claim 1, characterized in that, The additives include one or more of antioxidants, dispersants, wetting agents, defoamers, bentonite, and ethylene glycol.

5. The electromagnetic shielding interior wall coating according to claim 1, characterized in that, The solvent is water.

6. The electromagnetic shielding interior wall coating according to claim 1, characterized in that, The preparation method of the coating includes the following steps: 1) Add solvent, additives, fillers, nickel-plated zinc oxide whiskers, and graphene-crosslinked polymer composite material to the reactor and stir until homogeneous; 2) Add the base resin and film-forming aid to the reactor and stir evenly. Finally, add the leveling agent and stir evenly to obtain the electromagnetic shielding interior wall coating.

7. The electromagnetic shielding interior wall coating according to claim 6, characterized in that, After being stirred evenly in step 1), the fineness is <60μm.

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