Electromagnetic shielding filler, electromagnetic shielding coating comprising the same, preparation method and use thereof

Abstract

The present invention relates to a shielding filler, a shielding coating comprising the same, a preparation method and a use thereof. The shielding filler adopts melamine sponge as a carrier and surfaces thereof are covered with FeO.sub.x/graphene. The electromagnetic shielding coating is formed by mixing a component A and a component B in a molar ratio of (—OH).sub.A:(—NCO).sub.B=1:1, in which component A comprises fluorocarbon resin, elastic polyester resin, an electromagnetic filler, an auxiliary agent and a mixing solvent, and component B is isocyanate. The shielding filler of the present invention has a sponge-like macroporous structure, the pore wall surfaces of which are covered with ferrite and graphene, and the shielding filler has excellent electromagnetic shielding performance due to the electrical loss and magnetic loss. The obtained electromagnetic shielding coating layer is electrically conductive and magnetically inductive and has a broad electromagnetic shielding response frequency band. The obtained electromagnetic shielding coating layer has a low density, which is in line with the development trend of lightweight. The coating is convenient to use, and can be applied by brush coating, spray coating, or roller coating.

Claims

1. A shielding filler, wherein, the shielding filler adopts melamine sponge as a carrier and surfaces thereof are covered with FeO.sub.x/graphene; wherein, the FeO.sub.x exists in the following forms: one or more of Fe, FeO, Fe.sub.2O.sub.3 or Fe.sub.3O.sub.4; the FeO.sub.x accounts for 5% to 99% of the total mass of the shielding filler, and the graphene accounts for 1% to 95% of the total mass of the shielding filler.

2. The shielding filler according to claim 1, wherein, the shielding filler has a porosity of 65% to 85%, a saturation magnetization of 86 to 95 emu/g, a coercive force of 158 to 210 Oe, and a response frequency band of 100 kHz to 18 GHz.

3. A preparation method of a shielding filler, wherein, the method comprises the following steps: (1) preparing an aqueous dispersion solution of Fe.sup.3+-graphene oxide; (2) impregnating the melamine sponge with the Fe.sup.3+-graphene oxide solution to adsorb the Fe.sup.3+-graphene oxide solution, oven drying; and (3) subjecting the melamine sponge to high temperature treatment; preferably, step (1) specifically comprises the following steps: adding an iron salt into an aqueous dispersion solution of graphene oxide, and controlling the concentration of Fe.sup.3+ to be 5 mg/ml to 500 mg/ml; and/or, the concentration of the aqueous dispersion solution of graphene oxide is 0.5 mg/ml to 5 mg/ml, preferably 1.0 to 5.0 mg/ml; and/or, the iron salt is one or more selected from Fe(NO.sub.3).sub.3, FeCl.sub.3, Fe.sub.2(SO.sub.4).sub.3, and iron acetate; preferably, in step (3), the Fe.sup.3+-graphene oxide/melamine sponge obtained in step (2) is heated to 300° C. to 1200° C. for heat treatment, ground and sieved to obtain an FeO.sub.x/graphene electromagnetic shielding filler; the heat treatment temperature is preferably 500 to 800° C.; and/or, the heating rate is 1 to 20° C./min, more preferably 5 to 10° C./min.

4. A preparation method of electromagnetic shielding material for trains, aircrafts, ships or transformers, wherein the method comprises: using the shielding filler according to claim 1.

5. A shielding coating, which is formed by mixing a component A and a component B in a molar ratio of (—OH).sub.A:(—NCO).sub.B=1:1, wherein, the component A is prepared from the following raw materials in parts by weight: 25 to 55 parts of fluorocarbon resin, 5 to 25 parts of elastic polyester resin, 20 to 30 parts of the shielding filler according to claim 1, 1.5 to 4 parts of auxiliary agent, and 5 to 10 parts of mixed solvent; and the component B is isocyanate.

6. The shielding coating according to claim 5, wherein, the fluorocarbon resin is an ethylene polymer grafted with fluorine atoms; preferably GK570, polychlorotrifluoroethylene/vinyl ether resin (FEVE); and/or, the elastic polyester resin is an elastic polyester modified acrylic resin, and molecular formula of the elastic polyester modified acrylic resin contains irregular polyols with a high relative molecular mass and long-chain fatty acids; preferably, the elastic polyester resin is FTH elastic resin.

7. The shielding coating according to claim 5, wherein, the auxiliary agent is one or more selected from defoaming agent, leveling agent, dispersant agent or thixotropic agent; preferably, the defoaming agent is selected from BYK-530A, BYK110 or Deuchem 6800; and/or, the leveling agent is selected from BYK-320, EFKA3777 or EFKA-2022; and/or, the thixotropic agent is one or more selected from polyamide wax, organic bentonite or fumed silica; and/or, the mixed solvent consists of xylene, ethyl acetate, and cyclohexanone in a mass ratio of (2.0 to 5.0):(1.5 to 4.0):(2.5 to 6.0).

8. The preparation method of the shielding coating according to claim 5, wherein, the method comprises the following steps: (1) adding the fluorocarbon resin, elastic polyester resin, and auxiliary agent into 2/3 of the mixed solvent, mixing and stirring, slowly adding the electromagnetic shielding filler, dispersing evenly, then grinding to a fineness of 40 μm, adding the remaining mixed solvent, adjusting the system viscosity to 800 to 1000 cp, filtering and discharging to obtain component A; and (2) mixing the component A and component B, and stirring uniformly to prepare the electromagnetic shielding coating.

9. A preparation method of an electronic device in the fields of rail vehicles, aircrafts, ships or transformers, wherein the method comprises: using the shielding coating according to claim 5.

10. An electronic device, wherein, the electronic device comprises the coating layer prepared from the shielding coating according to claim 5.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a scanning electron microscope image of the FeO.sub.x/graphene electromagnetic shielding filler obtained by the present invention.

(2) FIG. 2 is a magnetic field shielding effectiveness curve of the electromagnetic shielding coating layer of the present invention in the range of 10 kHz to 30 MHz.

(3) FIG. 3 is an electric field shielding effectiveness curve of the electromagnetic shielding coating layer of the present invention in the range of 10 kHz to 30 MHz.

(4) FIG. 4 is an electromagnetic field shielding effectiveness curve of the electromagnetic shielding coating layer of the present invention in the range of 10 GHz to 18 GHz.

SPECIFIC MODES FOR CARRYING OUT THE EMBODIMENTS

(5) Exemplary embodiments of the present invention are provided in the following Examples. The following embodiments are given by way of examples only, and are used to assist a person skilled in the art in using the present invention. The Examples are not intended to limit the scope of the present invention in any way.

Example 1: An FeO.SUB.x./Graphene Electromagnetic Shielding Filler

(6) The present Example provides a FeO.sub.x/graphene electromagnetic shielding filler, which was prepared by the following method:

(7) (1) An aqueous dispersion solution of Fe(NO.sub.3).sub.3-graphene oxide was prepared.

(8) Fe(NO.sub.3).sub.3 was added into an aqueous dispersion solution of graphene oxide at a concentration of 5 mg/ml to prepare an aqueous dispersion solution of Fe(NO.sub.3).sub.3 with a concentration of 10 mg/ml.

(9) (2) Melamine sponge was impregnated and the Fe(NO.sub.3).sub.3-graphene oxide solution was adsorbed.

(10) The melamine sponge was impregnated in the aqueous dispersion solution of Fe(NO.sub.3).sub.3-graphene oxide obtained in the above step (1) for 2 h, then taken out and dried at 110° C. for 12 h.

(11) (3) A lightweight and efficient FeO.sub.x/graphene electromagnetic shielding filler was prepared by high temperature treatment.

(12) The dried Fe(NO.sub.3).sub.3-graphene oxide/melamine sponge was placed into a tubular furnace, heated up to 600° C. at the rate of 10° C./min and subjected to heat treatment for 3 h, then ground and sieved to obtain an FeO.sub.x/graphite electromagnetic shielding filler.

(13) After testing, the obtained shielding filler has a porosity of 85%, a saturation magnetization of 95 emu/g, a coercive force of 210 Oe, and an electromagnetic shielding response frequency band of 100 kHz to 18 GHz.

Example 2: A FeO.SUB.x./Graphene Electromagnetic Shielding Filler

(14) The present Example provides a FeO.sub.x/graphene electromagnetic shielding filler, which was prepared by the following method:

(15) (1) An aqueous dispersion solution of FeCl.sub.3-graphene oxide was prepared.

(16) FeCl.sub.3 was added into an aqueous dispersion solution of graphene oxide at a concentration of 1.0 mg/ml to prepare an aqueous dispersion solution of FeCl.sub.3 with a concentration of 100 mg/ml.

(17) (2) Melamine sponge was impregnated and the FeCl.sub.3-graphene oxide solution was adsorbed.

(18) The melamine sponge was impregnated in the aqueous dispersion solution of FeCl.sub.3-graphene oxide obtained in the above step (1) for 3 h, then taken out and dried at 100° C. for 20 h.

(19) (3) A lightweight and efficient FeO.sub.x/graphene electromagnetic shielding filler was prepared by high temperature treatment.

(20) The dried FeCl.sub.3-graphene oxide/melamine sponge was placed into a tubular furnace, heated up to 500° C. at the rate of 5° C./min and subjected to heat treatment for 4 h, then ground and sieved to obtain an FeO.sub.x/graphite electromagnetic shielding filler.

(21) After testing, the obtained shielding filler has a porosity of 65%, a saturation magnetization of 86 emu/g, a coercive force of 200 Oe, and an electromagnetic shielding response frequency band of 100 kHz to 18 GHz.

Example 3: A FeO.SUB.x./Graphene Electromagnetic Shielding Filler

(22) The present Example provides a FeO.sub.x/graphene electromagnetic shielding filler, which was prepared by the following method:

(23) (1) An aqueous dispersion solution of Fe(SO.sub.4).sub.3-graphene oxide was prepared.

(24) Fe(SO.sub.4).sub.3 was added into an aqueous dispersion solution of graphene oxide at a concentration of 2 mg/ml to prepare an aqueous dispersion solution of Fe(SO.sub.4).sub.3 with a concentration of 200 mg/ml.

(25) (2) Melamine sponge was impregnated and the Fe(SO.sub.4).sub.3-graphene oxide solution was adsorbed.

(26) The melamine sponge was impregnated in the aqueous dispersion solution of Fe(SO.sub.4).sub.3-graphene oxide obtained in the above step (1) for 5 h, then taken out and dried at 80° C. for 16 h.

(27) (3) A lightweight and efficient FeO.sub.x/graphene electromagnetic shielding filler was prepared by high temperature treatment.

(28) The dried Fe(SO.sub.4).sub.3-graphene oxide/melamine sponge was placed into a tubular furnace, heated up to 800° C. at the rate of 10° C./min and subjected to heat treatment for 5 h, then ground and sieved to obtain an FeO.sub.x/graphite electromagnetic shielding filler.

(29) After testing, the obtained shielding filler has a porosity of 78%, a saturation magnetization of 88 emu/g, a coercive force of 158 Oe, and an electromagnetic shielding response frequency band of 100 kHz to 18 GHz.

Example 4: Preparation of an Electromagnetic Shielding Coating

(30) The present Example provides a method for preparing a shielding coating, comprising the following steps:

(31) (1) 30 g of GK570 fluorocarbon resin, 15 g of FTH elastic polyester resin, 0.5 g of Deuchem 6800 auxiliary agent, 0.5 g of BYK110 auxiliary agent, 0.5 g of EFKA2020 auxiliary agent, and 0.5 g of EFKA3777 auxiliary agent were added into 7 g of mixed solvent, the resultant was mixed and stirred, 30 g of the electromagnetic shielding filler obtained in Example 1 was slowly added, and dispersed evenly, then the resultant was grinded to a fineness of 40 μm, and the remaining 3 g of mixed solvent was added, the system viscosity was adjusted to 800 to 1000 cp, and the resultant was filtered and discharged to obtain component A;

(32) the mixed solvent consists of 3.5 g of xylene, 3 g of ethyl acetate, and 3.5 g of cyclohexanone; and

(33) (2) component A and component B (isocyanate N3390) was mixed in a molar ratio of (—OH).sub.A:(—NCO).sub.B=1:1, and stirred uniformly to prepare an electromagnetic shielding coating.

Example 5

(34) The present Example provides a preparation method of a shielding coating, which is similar to Example 4 except that the formulation of component A was as follows:

(35) 25 g of GK570 fluorocarbon resin, 25 g of FTH elastic polyester resin, 0.3 g of 6800 auxiliary agent, 0.6 g of BYK110 auxiliary agent, 0.3 g of EFKA2020 auxiliary agent, 0.6 g of EFKA3777 auxiliary agent, 5 g of mixed solvent, and 20 g of electromagnetic shielding filler.

Example 6

(36) The present Example provides a preparation method of a shielding coating, which is similar to Example 4 except that the formulation of component A was as follows:

(37) 55 g of GK570 fluorocarbon resin, 5 g of FTH elastic polyester resin, 0.6 g of 6800 auxiliary agent, 0.3 g of BYK110 auxiliary agent, 0.6 g of EFKA2020 auxiliary agent, 0.4 g of EFKA3777 auxiliary agent, 8 g of mixed solvent, and 25 g of electromagnetic shielding filler.

(38) Effect Verification

(39) The performances of the shielding coating obtained in Examples 4-6 were tested, and the results were as follows:

(40) TABLE-US-00001 Saturation Response Density of Coating Resistiv- magnetiza- frequency the coating layer ity/Ω .Math. cm tion/emu/g band layer/g/m.sup.3 Example 4 0.05 78 10 KHz to 18 GHz 1.8 Example 5 2.0 21 10 KHz to 18 GHz 1.3 Example 6 0.4 54 10 KHz to 18 GHz 1.6

(41) Although the present invention has been described in detail with the general description and specific embodiments, it is obvious to a person skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the claimed scope of the present invention.

INDUSTRIAL APPLICABILITY

(42) The present invention provides a shielding filler, a shielding coating comprising the same, a preparation method and a use thereof. The shielding filler according to the present invention adopts melamine sponge as a carrier and surfaces thereof are covered with FeO.sub.x/graphene; wherein FeO.sub.x preferably exists in the following form: one or more of Fe, FeO, Fe.sub.2O.sub.3 or Fe.sub.3O.sub.4; the FeO.sub.x accounts for 5% to 99% of the total mass of the shielding filler, and graphene accounts for 1% to 95% of the total mass of the shielding filler. The shielding coating is formed by mixing a component A and a component B in a molar ratio of (—OH).sub.A:(—NCO).sub.B=1:1; wherein the component A is prepared from the following raw materials in parts by weight: 25 to 55 parts of fluorocarbon resin, 5 to 25 parts of elastic polyester resin, 20 to 30 parts of electromagnetic shielding filler, 1.5 to 4 parts of auxiliary agent and 5 to 10 parts of mixed solvent; and the component B is isocyanate. The shielding filler of the present invention has a sponge-like macroporous structure, the pore wall surfaces of which are covered with ferrite and graphene; and the shielding filler has excellent electromagnetic shielding performance due to the electrical loss and magnetic loss. The obtained electromagnetic shielding coating layer is electrically conductive and magnetically inductive and has a broad electromagnetic shielding response frequency band. The obtained electromagnetic shielding coating layer has a low density, which is in line with the development trend of lightweight. The coating is convenient to use, and can be applied by brush coating, spray coating, or roller coating, with good economic value and application prospects.