CN114644872B - Electromagnetic shielding coating and application thereof - Google Patents
Electromagnetic shielding coating and application thereof Download PDFInfo
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- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
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Abstract
The invention relates to an electromagnetic shielding coating, which comprises a coating A component and a coating B component, wherein the coating A component comprises, by weight, 30-50 parts of aqueous epoxy resin, 40-60 parts of silver-coated carbonyl iron powder, 1-4 parts of silver-coated carbon fiber and 15-30 parts of nano nickel powder; the coating B component contains a curing agent. According to the invention, the silver-coated carbonyl iron powder core-shell composite filler, the silver-coated carbon fiber and the nano nickel powder are reasonably compounded according to a specific proportion to be used as the conductive filler by taking the aqueous epoxy resin as a matrix, so that the aqueous broadband high-efficiency electromagnetic shielding coating is prepared, the coating can achieve better shielding effect when the thickness is 1mm, and the gaps and holes with larger sizes on the surface of the shielding body are repaired, so that the surface of the shielding body meets the conductive continuity, electromagnetic waves are prevented from entering the shielding body from conductive discontinuous points, and the coating can also be directly used as an electromagnetic shielding material to ensure the normal operation of equipment, and simultaneously meets the development trend of environmental friendliness.
Description
Technical Field
The invention relates to the field of coatings, in particular to an electromagnetic shielding coating and application thereof.
Background
In recent years, with the rapid development of the electronic information industry, various electronic and electric equipment provide great help for daily life and social construction of people. Meanwhile, the problems of electromagnetic radiation and interference generated in the working process of electronic and electric equipment also restrict the production and life of people, so that the electromagnetic pollution of human living space is also increasingly serious, the electromagnetic pollution becomes fourth pollution after noise pollution, water pollution and atmospheric pollution, and the electromagnetic waves of various frequency bands in the space seriously influence the health of human beings and the normal work of communication equipment. Therefore, it is necessary to block the propagation path of electromagnetic waves, and the electromagnetic shielding material can shield and protect precision instruments such as communication equipment, so as to limit the intensity of electromagnetic radiation within a safe range, thereby ensuring the normal operation of the equipment. In addition, because the whole communication equipment is inevitably provided with gaps and holes on the surface of the shielding body in the production, assembly and use processes, the electromagnetic interference and electromagnetic leakage caused by the gaps and holes bring great loss to people, and therefore, the development of broadband efficient electromagnetic shielding repair paint for ensuring the normal operation of the communication equipment is also necessary.
The traditional electromagnetic shielding materials are as follows: the electromagnetic wave absorption layer is brushed into a bottom coating, the electromagnetic wave reflection coating is sprayed into a surface coating after the bottom surface is dried, the scheme needs secondary spraying in the use process, the process is complicated, and xylene is used as a solvent, so that the environment and human body are greatly harmed; or polysulfide rubber is used as base rubber, metal powder and ferrite are used as composite filler, and the putty for preventing electromagnetic interference is prepared, and has larger thickness (generally larger than 1.5 mm) and poorer shielding efficiency, and is difficult to meet the use requirement of the current complex electromagnetic environment.
Therefore, the development of the electromagnetic shielding coating for solving the problems of larger thickness, insufficient shielding effectiveness, complex process and the like of the conventional electromagnetic shielding coating has important significance.
Disclosure of Invention
Based on the above, the invention provides the electromagnetic shielding coating, which can achieve better shielding effectiveness when the thickness is smaller.
The technical scheme for solving the technical problems is as follows.
An electromagnetic shielding coating comprises a coating A component and a coating B component, wherein the coating A component comprises the following components in parts by weight:
the coating B component contains a curing agent.
In some embodiments, the aqueous epoxy resin is selected from at least one of bisphenol a type epoxy resin and bisphenol F type epoxy resin.
In some embodiments, the particle size of the nano nickel powder in the electromagnetic shielding coating is 20 nm-80 nm.
In some embodiments, the length of the silver-coated carbon fiber in the electromagnetic shielding coating is 1 mm-2 mm.
In some embodiments, the silver Bao Tangji iron powder is at least one selected from silver Bao Pianzhuang carbonyl iron powder and silver Bao Zhenzhuang carbonyl iron powder, and has a particle size of 9 μm to 15 μm.
In some embodiments, the electromagnetic shielding coating composition a further comprises at least one of a dispersant, defoamer, corrosion inhibitor, thixotropic agent, and diluent.
In some embodiments, the electromagnetic shielding coating comprises at least one dispersant selected from BYK190 and S3060; and/or
The defoaming agent is at least one selected from silicone oil defoaming agents, polyether defoaming agents and polyether modified organic silicon defoaming agents; and/or
The corrosion inhibitor is at least one selected from water-soluble mercaptobenzothiazole and sodium benzoate.
In some embodiments, the thixotropic agent is at least one of fumed silica and precipitated silica and the diluent is water.
In some embodiments, the electromagnetic shielding coating comprises at least one curing agent selected from polyethylene polyamine and polyetheramine D-230.
In some embodiments, the electromagnetic shielding coating comprises 40 parts of bisphenol a type epoxy resin, 20 parts of silver Bao Pianzhuang carbonyl iron powder with the particle size of 10 mu m, 1 part of silver-coated carbon fiber with the length of 2mm, 15 parts of nano nickel powder with the particle size of 20nm, 190 parts of dispersant BYK, 20 parts of deionized water, 1 part of defoamer BYK-028 and 0.3 part of water-soluble mercaptobenzothiazole; the coating B component is 15 parts of polyethylene polyamine.
The invention also provides application of the electromagnetic shielding material.
Compared with the prior art, the electromagnetic shielding material has the following beneficial effects:
the electromagnetic shielding material adopts silver-coated carbonyl iron powder core-shell composite filler as conductive magnetic shielding filler, the silver plating layer on the surface has high conductivity, the surface impedance is not matched with free space, and electromagnetic waves are easy to reflect at an incident interface. And the metal material with high conductivity can generate stronger induction current under the action of electromagnetic waves, so that a strong reverse magnetic field is generated to offset the incident electromagnetic waves, and the silver plating layer on the surface of the silver-coated carbonyl iron powder can reflect and offset the incident electromagnetic waves to a greater extent. In addition, the carbonyl iron powder in the material can absorb electromagnetic waves which are not reflected, so that the shielding effectiveness of the material is further improved.
Furthermore, the silver-plated carbon fiber can generate stronger reflection on the incident electromagnetic wave, and the addition of the silver-plated carbon fiber increases the interface dimension and quantity inside the material, increases the times and paths of the reflection of the electromagnetic wave inside the material, and ensures that the electromagnetic wave becomes heat to dissipate after being reflected for many times inside the material. From the microstructure, silver-plated carbon fibers are lapped on the surfaces of silver-coated carbonyl iron powder which are far away from each other, so that the probability of contact between conductive fillers is increased, potential barriers of electron transition between the silver-coated carbonyl iron powder are greatly reduced, and under the same condition, the number of electrons passing through particle boundaries in unit time is increased, and the eddy current effect is enhanced.
Furthermore, the nano nickel powder fills the gaps among the silver-coated carbonyl iron powder, reduces the overall porosity of the material system, eliminates the conductive discontinuous points inside the material to a certain extent, ensures that the conductive filler can form a good conductive network on microcosmic scale under lower filling amount, and improves the overall conductivity of the material.
According to the invention, the water-based broadband efficient electromagnetic shielding coating is prepared by taking the water-based epoxy resin as a matrix, reasonably compounding the silver-coated carbonyl iron powder core-shell composite filler, the silver-coated carbon fiber and the nano nickel powder according to a specific proportion as the conductive filler, and the coating can achieve better shielding effect when the thickness is 1 mm. The electromagnetic shielding coating prepared by the invention can repair gaps and holes with larger sizes on the surface of the shielding body, so that the surface of the shielding body meets the conductive continuity, electromagnetic waves are prevented from entering the shielding body from conductive discontinuous points, and the electromagnetic shielding coating can also be directly used as an electromagnetic shielding material to ensure the normal operation of equipment, and meets the development trend of environmental friendliness.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of the preparation of an electromagnetic shielding coating according to an embodiment;
fig. 2 is a schematic diagram of electromagnetic shielding mechanism.
Detailed Description
The electromagnetic shielding material of the present invention will be described in further detail with reference to specific examples. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
An embodiment of the invention provides an electromagnetic shielding coating, which comprises a coating A component and a coating B component, wherein the coating A component comprises the following components in parts by weight:
the coating B component contains a curing agent.
In some examples, the electromagnetic shielding coating may be used with a coating a component and a coating B component in a mix ratio of 20 by weight: mixing the ingredients according to the proportion of (1-2).
Preferably, in use, the coating A and B components are mixed and dosed in a 15:1 ratio by weight.
In some examples, the aqueous epoxy resin is selected from at least one of bisphenol a type epoxy resin and bisphenol F type epoxy resin.
Preferably, the aqueous epoxy resin is a bisphenol a type epoxy resin.
In some examples, the particle size of the nano nickel powder in the electromagnetic shielding coating is 20nm to 80nm. For example, the particle size of the nano nickel powder is 20nm, 25nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm.
Preferably, the particle size of the nano nickel powder is 20nm.
In some examples, the length of the silver-coated carbon fiber in the electromagnetic shielding paint is 1mm to 2mm. It is understood that the length of the silver-coated carbon fiber may be 1mm, 1.5mm, 2mm.
Preferably, the length of the silver-coated carbon fiber is selected from 2mm.
In some examples, the silver Bao Tangji iron powder is at least one selected from silver Bao Pianzhuang carbonyl iron powder and silver Bao Zhenzhuang carbonyl iron powder, and has a particle size of 9 μm to 15 μm, for example, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, and 15 μm.
Preferably, the silver Bao Tangji iron powder is silver Bao Pianzhuang carbonyl iron powder with a particle size of 10 μm.
In some examples, the electromagnetic shielding coating includes at least one curing agent selected from polyethylene polyamine and polyetheramine D-230.
Preferably, the curing agent is a polyethylene polyamine.
In some examples, the electromagnetic shielding coating, the coating a-component further includes at least one of a dispersant, a defoamer, a corrosion inhibitor, a thixotropic agent, and a diluent.
In some examples, the dispersant is selected from at least one of BYK190 and S3060.
Preferably, the dispersant is BYK 190.
In some examples, the electromagnetic shielding coating includes at least one defoamer selected from the group consisting of silicone oil defoamers, polyether defoamers, and polyether modified silicone defoamers.
Optionally, the defoamer is selected from silicone oil defoamers.
In some examples, the electromagnetic shielding coating comprises a corrosion inhibitor selected from at least one of water-soluble mercaptobenzothiazole and sodium benzoate.
Preferably, the corrosion inhibitor is water-soluble mercaptobenzothiazole.
In some examples, the thixotropic agent is at least one of fumed silica and precipitated silica in the electromagnetic shielding coating.
In some examples, the electromagnetic shielding coating includes a diluent.
In a preferred embodiment, the electromagnetic shielding coating comprises 40 parts of bisphenol A type epoxy resin, 20 parts of silver Bao Pianzhuang carbonyl iron powder with the particle size of 10 mu m, 1 part of silver-coated carbon fiber with the length of 2mm, 15 parts of nano nickel powder with the particle size of 20nm, 190 parts of dispersing agent BYK 3 parts, 20 parts of deionized water, 1 part of defoaming agent BYK-028 and 0.3 part of water-soluble mercapto benzothiazole; the coating B component is 15 parts of polyethylene polyamine.
The invention also provides application of the electromagnetic shielding material.
The water-based broadband efficient electromagnetic shielding coating prepared by the invention is viscous liquid at room temperature, and can be diluted according to actual use conditions, and construction is performed by adopting processes such as spraying, knife coating and the like.
The aqueous electromagnetic shielding coating is prepared by taking aqueous epoxy resin as a matrix and conductive filler as a shielding agent, wherein the conductive filler is prepared by compounding silver-coated carbonyl iron powder core-shell composite filler, silver-coated carbon fiber and nano nickel powder, and further adding an auxiliary agent and a curing agent to mix to obtain a viscous liquid. The silver Bao Pianzhuang carbonyl iron powder has the functions of reflecting and absorbing electromagnetic waves, silver-plated carbon fibers are used as conductive bridges to connect conductive particles which are far away from each other under a smaller filling amount, more interfaces are introduced into the material, multiple reflection loss is increased, gaps among the flaky silver-coated carbonyl iron powder are filled with nano nickel powder with the size of 20-80 nm, the porosity of the material is reduced, and the whole filler can form a good conductive network under the smaller filling amount and has higher conductivity.
An embodiment of the invention provides a preparation method of silver-coated carbonyl iron powder, which comprises steps S10-S20.
Step S10: placing an absolute ethyl alcohol solution containing polyvinylpyrrolidone into an absolute ethyl alcohol solution containing carbonyl iron powder, stirring, and adding formaldehyde to prepare a mixture A;
step S20: and mixing the mixture A with silver ammonia solution to prepare silver-coated carbonyl iron powder.
In some examples, in step S20, the mixing volume ratio of the mixture A and the silver ammonia solution is (1-2): 1.
An embodiment of the invention provides a preparation method of silver-coated carbon fibers, which comprises step S30.
Step S30: and mixing the carbon fiber with silver ammonia solution to prepare the silver-coated carbon fiber.
In some examples, in step S30, the pretreatment of the carbon fibers prior to mixing the carbon fibers with the silver ammonia solution further includes steps S31-S36.
Step S31: removing the photoresist, and burning in a box-type resistance furnace at 400 ℃.
Step S32: deoiling, and soaking in acetone at room temperature.
Step S33: coarsening, and treating with 100g/L sulfuric acid solution at room temperature.
Step S34: sensitization, 20g/L SnCl at room temperature 2 Soaking in the solution.
Step S35: activating, 0.5g/L PdCl at 40-50 DEG C 2 Soaking in the solution.
Referring to fig. 1, an embodiment of the present invention provides a method for preparing an electromagnetic shielding coating, which includes steps S40 to S70.
Step S40: and adding a diluent into the aqueous epoxy resin, and stirring to obtain a diluent of the aqueous epoxy resin.
Step S50: and adding a dispersing agent, a defoaming agent, a corrosion inhibitor and a thixotropic agent in sequence in the stirring process to obtain a mixture D.
Step S60: and mixing the mixture D with silver Bao Tangji iron powder, silver-coated carbon fibers and nano nickel powder to obtain a component A of the coating.
Step S70: the component A and the component B are mixed by taking the component containing the curing agent as the component B.
The invention prepares the water-based broadband efficient electromagnetic shielding coating, can repair gaps and holes with larger surface sizes of the shielding body, eliminates conductive discontinuous points on the surface of the shielding body through repairing the gaps and holes on the surface of the shielding body, ensures that the whole surface of the shielding body meets the conductive continuity, prevents electromagnetic waves from entering the shielding body from the conductive discontinuous points, and can also be directly used as an electromagnetic shielding material to ensure the normal operation of equipment. By repairing the damaged shielding body, the service life of the shielding body material is prolonged, and the replacement frequency of the shielding body is reduced. The prepared electromagnetic shielding coating can realize higher shielding effectiveness in a wider frequency range by compounding silver Bao Tangji iron powder, nano nickel powder and silver-coated carbon fiber as a shielding agent.
Referring to fig. 2, the shielding effectiveness of the shielding material mainly includes reflection loss, absorption loss and multiple reflection loss, i.e., shielding effectiveness se=a+r+b. The silver-coated carbonyl iron powder core-shell composite filler is used as an electric conduction magnetic conduction shielding filler, the silver plating layer on the surface has high electric conductivity, the surface impedance is not matched with free space, and electromagnetic waves are easy to reflect at an incident interface. Secondly, the metal material with high conductivity can generate stronger induction current under the action of electromagnetic waves, so that a strong reverse magnetic field is generated to offset the incident electromagnetic waves, and the silver plating layer on the surface can reflect and offset the incident electromagnetic waves to a greater extent. The internal sheet carbonyl iron powder can absorb electromagnetic waves which are not reflected, so that the shielding effectiveness of the material is further improved. In addition, the putty is inevitably subjected to the action of external force in the blade coating process, and under the action of external force, flaky particles are more easy to deform such as expansion, crushing and fracture of the flakes, so that the contact quality between conductive particles can be enhanced, and the conductive network of the coating is improved.
The silver-plated carbon fiber can also generate stronger reflection on the incident electromagnetic wave, and the addition of the silver-plated carbon fiber increases the interface dimension and quantity inside the material, increases the times and paths of the reflection of the electromagnetic wave inside the material, and ensures that the electromagnetic wave becomes heat to dissipate after being reflected for many times inside the material. From the microstructure, silver-plated carbon fibers are lapped on the surfaces of silver-coated carbonyl iron powder which are far away from each other, so that the probability of contact between conductive fillers is increased, potential barriers of electron transition between the silver-coated carbonyl iron powder are greatly reduced, and under the same condition, the number of electrons passing through the boundary of flaky particles in unit time is increased, and the eddy current effect is enhanced. Furthermore, the nano nickel powder fills up gaps among the flaky silver-coated carbonyl iron powder, reduces the overall porosity of a material system, eliminates conductive discontinuous points inside the material to a certain extent, ensures that the conductive filler can form a good conductive network on microcosmic scale under lower filling amount, and improves the overall conductivity of the material.
The broadband high-efficiency electromagnetic shielding coating prepared by the invention can be used as a shielding material to avoid the interference of complex electromagnetic environment received by the equipment, and can be used as a repairing material to repair gaps and holes on the surface of the existing shielding body, so that the conductive discontinuous points on the surface of the shielding body are eliminated, the whole surface of the shielding body can meet the conductive continuity, the original shielding efficiency is recovered, and the replacement frequency of the shielding material is reduced.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The following examples of the electromagnetic shielding coating material and the method for preparing the same according to the present invention, it is understood that the electromagnetic shielding coating material and the method for preparing the same according to the present invention are not limited to the following examples.
The silver Bao Tangji iron powder and silver-coated carbon fiber used in the following examples were synthesized according to the following steps:
preparation of silver-coated carbonyl iron powder
1) 40g of polyvinylpyrrolidone (PVP) was weighed, 1L of absolute ethyl alcohol was added, and the mixture was completely dissolved under magnetic stirring to prepare 40g/L of polyvinylpyrrolidone (PVP) absolute ethyl alcohol solution.
200g of carbonyl iron powder is weighed, 1L of absolute ethyl alcohol is added, the mixture is uniformly dispersed under the action of an electric stirrer at the rotating speed of 200rpm/min, and the prepared PVP ethanol solution is poured into the mixture and is continuously stirred for 30min, so that uniform dispersion is ensured. 30ml of formaldehyde solution was pipetted into the above mixture and stirring was continued for 30min to obtain mixture A.
2) Preparing silver ammonia solution: distilled water and 0.25M silver nitrate, 2.5M ammonia water were taken to prepare a silver ammonia solution, and ph=13.0 was adjusted with sodium hydroxide.
3) Preparing silver-coated carbonyl iron powder core-shell composite particles: mixing the mixture A with silver ammonia solution according to the volume ratio of 1:1, mixing, stirring at 200rpm/min at room temperature for 2 hours,
4) And (3) suction filtration: washing with distilled water until the pH value of the clear liquid is 7, drying in a vacuum drying oven at 80 ℃, scattering and screening to obtain the silver-coated carbonyl iron powder core-shell structure composite particles.
Preparing silver-coated carbon fibers:
1) Pretreatment of
Removing photoresist: burning in a box-type resistance furnace at 400 ℃ for 20min.
Deoiling: soaking in acetone at room temperature for 5min.
Coarsening: 100g/L sulfuric acid solution at room temperature for 15min.
Sensitization: snCl of 20g/L at room temperature 2 Soaking the solution for 5min.
Activating: pdCl at 40℃at 0.5g/L 2 The solution was soaked for 10min.
2) And mixing the carbon fiber with silver ammonia solution to prepare the silver-coated carbon fiber. The reaction was stirred at 150rpm/min at room temperature for 2h, the carbon fibers were washed with distilled water to a clear solution ph=7, filtered and dried in a vacuum oven at 80 ℃ for further use.
Example 1
Adding 7.5 parts of deionized water into 50 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 1902.5 parts of dispersing agent BYK, 1.5 parts of silicone oil type defoamer, 0.5 part of corrosion inhibitor water-soluble mercapto benzothiazole, 50 parts of 12 mu m silver Bao Pianzhuang carbonyl iron powder, 1.5 parts of 1mm silver carbon-coated fiber and 20 parts of 60nm nano nickel powder in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to the ratio of 15:1, pouring the mixture into a polytetrafluoroethylene mould with the thickness of 600 multiplied by 1mm, putting the mixture into a vacuum oven to remove bubbles, and curing the mixture in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Example 2
Adding 7.5 parts of deionized water into 50 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 190 parts of dispersing agent BYK, 3 parts of fumed silica, 1.5 parts of silicone oil type defoamer, 0.5 part of corrosion inhibitor water-soluble mercapto benzothiazole, 50 parts of 12 mu m silver Bao Pianzhuang carbonyl iron powder, 1.5 parts of 2mm silver carbon-coated fiber and 20 parts of 60nm nano nickel powder in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to the ratio of 15:1, pouring the mixture into a 600X 600 PP plate to be coated with a coating with the thickness of 1mm, putting the coating into a vacuum oven to remove bubbles, and curing the coating in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Example 3
Adding 7.5 parts of deionized water into 50 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 3.5 parts of a dispersing agent BYK 190.5 parts, 1.5 parts of a silicone oil type defoamer, 0.5 part of corrosion inhibitor water-soluble mercapto benzothiazole, 50 parts of 9 mu m silver Bao Pianzhuang carbonyl iron powder, 1.5 parts of 2mm silver carbon-coated fiber and 20 parts of 60nm nano nickel powder in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to the ratio of 15:1, pouring the mixture into a 600X 600 PP plate to be coated with a coating with the thickness of 1mm, putting the coating into a vacuum oven to remove bubbles, and curing the coating in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Example 4
Adding 10 parts of deionized water into 30 parts of bisphenol F epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 190 parts of dispersing agent BYK, 3 parts of silicone oil defoamer, 1 part of corrosion inhibitor water-soluble mercapto benzothiazole, 60 parts of 10 mu m silver Bao Pianzhuang carbonyl iron powder, 2 parts of 1mm silver carbon-coated fiber, 2 parts of 2mm silver carbon-coated fiber and 15 parts of 80nm nano nickel powder in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to the ratio of 15:1, pouring the mixture into a 600X 600 PP plate to be coated with a coating with the thickness of 1mm, putting the coating into a vacuum oven to remove bubbles, and curing the coating in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Example 5
Adding 20 parts of deionized water into 40 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 190 parts of dispersing agent BYK, 1 part of silicone oil defoamer, 0.3 part of corrosion inhibitor water-soluble mercaptobenzothiazole, 20 parts of 15 mu m silver Bao Pianzhuang carbonyl iron powder, 20 parts of 10 mu m silver Bao Zhenzhuang carbonyl iron powder, 1 part of 2mm silver carbon-coated fiber and 15 parts of 80nm nano nickel powder in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to the ratio of 15:1, pouring the mixture into a 600X 600 PP plate to be coated with a coating with the thickness of 1mm, putting the coating into a vacuum oven to remove bubbles, and curing the coating in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Example 6
Adding 20 parts of deionized water into 40 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 190 parts of dispersing agent BYK, 1 part of silicone oil defoamer, 0.3 part of corrosion inhibitor water-soluble mercaptobenzothiazole, 20 parts of 15 mu m silver Bao Pianzhuang carbonyl iron powder, 20 parts of 10 mu m silver Bao Zhenzhuang carbonyl iron powder, 1 part of 2mm silver carbon-coated fiber and 15 parts of 20nm nano nickel powder in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to the ratio of 15:1, pouring the mixture into a 600X 600 PP plate to be coated with a coating with the thickness of 1mm, putting the coating into a vacuum oven to remove bubbles, and curing the coating in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Comparative example 1
Adding 7.5 parts of deionized water into 50 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 1901.5 parts of dispersing agent BYK, 1.5 parts of silicone oil type defoamer, 0.5 part of corrosion inhibitor water-soluble mercapto benzothiazole, 50 parts of 15 mu m silver Bao Pianzhuang carbonyl iron powder and 20 parts of 80nm nano nickel powder in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain the component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to the ratio of 15:1, pouring the mixture into a polytetrafluoroethylene mould with the thickness of 600 multiplied by 1mm, putting the mixture into a vacuum oven to remove bubbles, and curing the mixture in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Comparative example 2
Adding 7.5 parts of deionized water into 50 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 1903 parts of dispersant BYK, 3 parts of fumed silica, 1.5 parts of silicone oil type defoamer, 0.5 part of corrosion inhibitor water-soluble mercapto benzothiazole, 50 parts of 12 mu m silver Bao Pianzhuang carbonyl iron powder and 1.5 parts of 2mm silver carbon-coated fiber in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to a ratio of 13:1, pouring the mixture into a 600X 600 PP plate to be coated with a coating with a thickness of 1mm, putting the coating into a vacuum oven to remove bubbles, and curing the coating in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Comparative example 3
Adding 7.5 parts of deionized water into 50 parts of bisphenol A epoxy resin, uniformly stirring at a rotating speed of 200rpm/min, then sequentially adding 2.5 parts of a dispersing agent BYK 190.5 parts, 3 parts of fumed silica, 1.5 parts of a silicone oil type defoamer, 0.5 part of a corrosion inhibitor water-soluble mercapto benzothiazole, 50 parts of 9 mu m silver Bao Pianzhuang carbonyl iron powder, 0.75 part of 1mm silver carbon-coated fiber and 0.75 part of 2mm silver carbon-coated fiber in the stirring process, stirring for 1h, and performing ultrasonic dispersion for 20min to obtain a component A. The component B is a curing agent, and polyethylene polyamine is selected as the curing agent.
Uniformly mixing the component A and the component B according to a ratio of 13:1, pouring the mixture into a 600X 600 PP plate to be coated with a coating with a thickness of 1mm, putting the coating into a vacuum oven to remove bubbles, and curing the coating in the oven according to the conditions of 50 ℃/1h,60 ℃/2h and 70 ℃/3h to obtain a test sample.
Comparative example 4
Substantially the same as in example 6, except that the nano nickel powder of 60nm in example 6 was replaced with the nano nickel powder of 100 nm.
Comparative example 5
Substantially the same as in example 6, except that the nano nickel powder of 60nm in example 6 was replaced with the nano nickel powder of 10 nm.
Comparative example 6
Substantially the same as in example 6, except that silver Bao Pianzhuang carbonyl iron powder in example 6 was replaced with silver Bao Qiuzhuang carbonyl iron powder.
Comparative example 7
Substantially the same as in example 6, except that silver Bao Pianzhuang carbonyl iron powder in example 6 was replaced with flake carbonyl iron powder.
The electromagnetic shielding materials prepared in examples and comparative examples were subjected to shielding effectiveness tests in the range of 100MHz to 10GHz according to GJB6190-2008, respectively, as shown in table 1.
The electromagnetic shielding materials prepared in examples and comparative examples were subjected to surface adhesion test according to SJ/T1552-1995, respectively; the electromagnetic shielding materials prepared in examples and comparative examples were respectively subjected to a coating impact resistance test according to GB/T1732-1993; the electromagnetic shielding materials prepared in examples and comparative examples were subjected to product resistivity tests according to GB/T2439-2001, respectively, as shown in Table 2.
TABLE 1
TABLE 2
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As can be seen from tables 1 to 2, compared with comparative examples 1 to 7, the electromagnetic shielding coating prepared in examples 1 to 6 has a better shielding effectiveness, up to 100dB and a smaller volume resistivity at 6GHz, which means that the conductivity of the coating can be greatly improved by grading the conductive fillers with different appearances, and further the shielding effect is improved, and as can be seen from examples 1 to 6 and comparative examples 1 to 7, the shielding effectiveness in the tested frequency band is more than or equal to 63dB, in particular, the combined volume resistivity of the flaky silver Bao Tangji iron powder and the silver Bao Zhenzhuang carbonyl iron powder in example 6 is the lowest, the shielding effectiveness in the whole frequency band is more than or equal to 73dB, the effect is best, and the minimum volume resistivity in the comparative example is 0.013 Ω cm, and the shielding effectiveness in the tested frequency band is more than or equal to 50 dB. According to the invention, the water-based epoxy resin is used as a matrix, the silver-coated carbonyl iron powder core-shell composite filler, the silver-coated carbon fiber and the nano nickel powder are reasonably compounded according to a specific proportion to be used as the conductive filler, and the prepared electromagnetic shielding coating can achieve better shielding effect when the thickness is 1 mm.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (9)
1. An electromagnetic shielding coating is characterized by comprising a coating A component and a coating B component, wherein the coating A component comprises the following components in parts by weight:
the coating B component contains a curing agent;
the particle size of the nano nickel powder is 20 nm-80 nm, and the silver Bao Tangji iron powder is silver Bao Pianzhuang carbonyl iron powder.
2. The electromagnetic shielding paint of claim 1, wherein the aqueous epoxy resin is selected from at least one of bisphenol a type epoxy resin and bisphenol F type epoxy resin.
3. The electromagnetic shielding paint of claim 1, wherein the silver-coated carbon fiber has a length of 1mm to 2mm.
4. The electromagnetic shielding paint according to claim 1, wherein the particle size of the silver Bao Tangji iron powder is 9 μm to 15 μm.
5. The electromagnetic shielding coating of any one of claims 1-4, wherein the coating a-component further comprises at least one of a dispersant, a defoamer, a corrosion inhibitor, a thixotropic agent, and a diluent.
6. The electromagnetic shielding paint of claim 5, wherein the dispersant is selected from at least one of BYK190 and S3060; and/or
The defoaming agent is at least one selected from silicone oil defoaming agents, polyether defoaming agents and polyether modified organic silicon defoaming agents; and/or
The corrosion inhibitor is selected from at least one of water-soluble mercaptobenzothiazole and sodium benzoate; and/or
The thixotropic agent is at least one of fumed silica and precipitated silica; and/or
The diluent is water.
7. The electromagnetic shielding coating of any one of claims 1-4 and 6, wherein the curing agent is selected from at least one of polyethylene polyamine and polyetheramine D-230.
8. The electromagnetic shielding coating as set forth in claim 1, wherein the coating a component comprises, in parts by weight, 40 parts of bisphenol a type epoxy resin, 20 parts of silver Bao Pianzhuang carbonyl iron powder with a particle size of 10 μm, 1 part of silver-coated carbon fiber with a length of 2mm, 15 parts of nano nickel powder with a particle size of 20nm, 190 parts of dispersant BYK, 20 parts of deionized water, 1 part of defoamer BYK-028 and 0.3 part of water-soluble mercaptobenzothiazole; the coating B component is 15 parts of polyethylene polyamine.
9. Use of the electromagnetic shielding coating according to any one of claims 1 to 8 for the preparation of electromagnetic shielding materials.
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| CN1974841A (en) * | 2006-12-01 | 2007-06-06 | 广东工业大学 | Core-shell type composite conductive Fe-Ag filler and its prepn process |
| CN105038513A (en) * | 2015-08-25 | 2015-11-11 | 无锡市长安曙光手套厂 | Water-based conductive coating composition |
| CN106752632A (en) * | 2016-12-19 | 2017-05-31 | 安徽钟南人防工程防护设备有限公司 | A kind of closed guard gate's electromagnetic-shielding conductive coating and preparation method thereof |
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| CN1974841A (en) * | 2006-12-01 | 2007-06-06 | 广东工业大学 | Core-shell type composite conductive Fe-Ag filler and its prepn process |
| CN105038513A (en) * | 2015-08-25 | 2015-11-11 | 无锡市长安曙光手套厂 | Water-based conductive coating composition |
| CN106752632A (en) * | 2016-12-19 | 2017-05-31 | 安徽钟南人防工程防护设备有限公司 | A kind of closed guard gate's electromagnetic-shielding conductive coating and preparation method thereof |
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