阅读说明：本技术 一种具有自修复功能的电磁屏蔽材料及其制备方法和应用 (Electromagnetic shielding material with self-repairing function and preparation method and application thereof ) 是由 赖登国 汪印 陈笑笑 于 2021-09-09 设计创作，主要内容包括：本发明提供一种具有自修复功能的电磁屏蔽材料及其制备方法和应用,所述电磁屏蔽材料的制备原料包括聚丙烯酸、氯化钙、水溶性高分子、碳材料和水溶性碳酸盐的组合；其中氯化钙可以和水溶性碳酸盐反应形成无定型碳酸钙,所述无定型碳酸钙、聚丙烯酸和水溶性高分子可以共同作为基体形成水凝胶,使得碳材料分散在基体中形成导电网络,保证得到的材料具有自修复功能的同时还赋予了材料优异的电磁屏蔽性能,最终得到了兼具优异自修复和电磁屏蔽性能的复合材料。(The invention provides an electromagnetic shielding material with a self-repairing function, a preparation method and application thereof, wherein the preparation raw materials of the electromagnetic shielding material comprise polyacrylic acid, calcium chloride, water-soluble polymers, carbon materials and a combination of water-soluble carbonates; the calcium chloride can react with water-soluble carbonate to form amorphous calcium carbonate, and the amorphous calcium carbonate, polyacrylic acid and water-soluble polymer can be jointly used as a matrix to form hydrogel, so that the carbon material is dispersed in the matrix to form a conductive network, the obtained material has a self-repairing function, and meanwhile, the material is endowed with excellent electromagnetic shielding performance, and finally, the composite material with excellent self-repairing and electromagnetic shielding performance is obtained.)

1. The electromagnetic shielding material with the self-repairing function is characterized in that raw materials for preparing the electromagnetic shielding material comprise polyacrylic acid, calcium chloride, water-soluble polymers, carbon materials and a combination of water-soluble carbonates.

2. Electromagnetic shielding material according to claim 1, characterized in that the polyacrylic acid has a molecular weight of 1000 to 100000g/mol, preferably 2000 to 5000 g/mol.

3. The electromagnetic shielding material according to claim 1 or 2, wherein the water-soluble polymer comprises any one or a combination of at least two of polyvinyl alcohol, polyacrylamide, chitosan, carboxymethyl cellulose salt, carboxymethyl cellulose, alginate, methyl cellulose, gelatin, dextran, or agarose;

the mass ratio of the water-soluble polymer to the polyacrylic acid is preferably (0.1-10): 100, and more preferably (0.5-5): 100.

4. The electromagnetic shielding material according to any one of claims 1 to 3, wherein the molar ratio of the calcium chloride to the polyacrylic acid is 1 (0.5 to 1.5).

5. The electromagnetic shielding material according to any one of claims 1 to 4, wherein the carbon material comprises any one or a combination of at least two of graphene, carbon nanotubes, carbon black, activated carbon or porous carbon, preferably graphene;

preferably, the mass ratio of the carbon material to the polyacrylic acid is (1-20): 100, and more preferably (1-10): 100;

preferably, the water-soluble carbonate includes any one of sodium carbonate, potassium carbonate or ammonium carbonate or a combination of at least two thereof, and is further preferably sodium carbonate.

6. A method for preparing an electromagnetic shielding material according to any one of claims 1 to 5, comprising the steps of:

(1) dispersing polyacrylic acid, calcium chloride, water-soluble polymer and carbon material in water to obtain a mixed solution;

(2) and (2) adding an aqueous solution of water-soluble carbonate into the mixed solution obtained in the step (1) for reaction to obtain the electromagnetic shielding material.

7. The method according to claim 6, wherein the polyacrylic acid is used in an amount of 0.01 to 1mol, preferably 0.05 to 0.5mol, based on 1L of the mixed solution in step (1);

preferably, the amount of the calcium chloride is 0.01 to 1mol, and more preferably 0.05 to 0.5mol, based on 1L of the mixed solution in the step (1).

8. The method according to claim 6 or 7, wherein the water-soluble carbonate has a molar number of 0.1 to 1mol, preferably 0.2 to 0.5mol, based on 1L of the aqueous solution of the water-soluble carbonate in the step (2);

preferably, the adding method in the step (2) is dropwise adding.

9. The preparation method according to any one of claims 6 to 8, characterized by further comprising a step of washing after the reaction in the step (2);

preferably, the washing comprises a deionized water washing.

10. Use of an electromagnetic shielding material according to any one of claims 1 to 5 in an electronic device.

Technical Field

The invention belongs to the technical field of electromagnetic shielding materials, and particularly relates to an electromagnetic shielding material with a self-repairing function, and a preparation method and application thereof.

Background

The rapid development of wireless communication technology and intelligent electronic equipment brings convenience to the life of people, and simultaneously, the problem of non-negligible electromagnetic radiation pollution is also generated, and adverse effects are brought to the performance of the equipment, the health of human bodies and the surrounding environment. Particularly, with the commercialization of 5G network and Internet of things products, the problem of electromagnetic wave pollution is increasingly prominent, and the development of high-performance electromagnetic shielding materials is very important for eliminating electromagnetic radiation leakage, so that the normal operation of 5G communication, automatic driving, remote medical operation, industrial remote control and precise electronic products is ensured. The conventional metal material becomes the first choice of the current electromagnetic shielding material due to excellent electrical conductivity, but the metal material has the defects of poor mechanical flexibility, difficult processing, easy corrosion, high density and the like, so that the application in the fields of aerospace and next generation of intelligent electronics is limited, and the development of novel shielding materials for replacing traditional metals is imperative.

At present, carbon-based shielding materials prepared from graphene, carbon nanotubes, carbon fibers, activated carbon and the like have the advantages of light weight, corrosion resistance, adjustable performance and the like, are favored by researchers, are substitute materials of traditional electromagnetic shielding materials, and successively develop carbon-based polymer composite materials, carbon aerogel materials, carbon film materials and the like.

CN110408337A discloses a preparation method of an electromagnetic shielding tape modified by aerogel containing elastic carbon, which comprises the following steps: adding resorcinol and nano-fibers into a formaldehyde water solution, and adding sodium carbonate to obtain an aerogel precursor solution; coating the aerogel precursor solution on the surface of a metal copper foil, heating and curing, introducing carbon dioxide, heating and drying, and carbonizing at high temperature to obtain an elastic carbon aerogel modified copper foil; stirring and drying the resorcinol-formaldehyde aerogel precursor solution in a carbon dioxide atmosphere, and carbonizing at a high temperature to obtain carbon aerogel powder; mixing polyacrylate with purified carbon aerogel powder, a curing agent and a dispersing agent to obtain the carbon-based polyacrylate conductive pressure-sensitive adhesive; coating carbon-based polyacrylate conductive pressure-sensitive adhesive on the surface of the conductive cloth, and heating and curing to prepare a double-sided conductive adhesive tape; and finally, performing pressurized cladding on the electromagnetic shielding adhesive tape and the release film and the copper foil modified by the elastic carbon aerogel to prepare the electromagnetic shielding adhesive tape modified by the elastic carbon aerogel.

CN113120879A discloses a carbon aerogel material and a preparation method and application thereof, wherein the carbon aerogel material is prepared by mixing nano-cellulose-graphene oxide aqueous dispersion with polymethyl methacrylate solution to obtain a Pickering emulsion of oil-in-water with stable nano-cellulose; then freezing to obtain the nano-cellulose-graphene oxide/polymethyl methacrylate composite aerogel; and then annealing to obtain the carbon aerogel material. The carbon aerogel material with the three-dimensional structure prepared by the invention has high compressive strain, excellent fatigue resistance, excellent electromagnetic shielding performance and biosensing performance, and has wide application prospect in the fields of flexible sensors and electromagnetic interference shielding.

CN109763210A discloses a method for preparing cellulose-based carbon fiber or carbon film by using ionic liquid. Taking the ionic liquid as a solvent to efficiently dissolve cellulose and disperse carbon nano materials at the same time to obtain an ionic liquid-cellulose-carbon nano composite solution; spinning or scraping the composite solution to prepare a conductive fiber or a conductive film; and further preparing the cellulose-based carbon fiber or the carbon film with high conductivity by pre-oxidation and carbonization treatment. The method has the advantages of simple process, rich cellulose source, low price, environment-friendly and recoverable ionic liquid, and the carbon nano tube, the graphene and the conductive carbon black are added into the cellulose matrix, so that the conductivity of the carbon fiber or the carbon film is greatly improved, and the method can be applied to the fields of antistatic textiles, electric heating clothes, electromagnetic shielding fabrics and the like and has wide application prospect.

At present, the method for improving the electromagnetic shielding performance of the material by improving the conductivity of the material is effective to reduce the thickness of the material to a certain extent. However, the method for improving the conductivity of the material usually involves extremely high heat treatment operation temperature, such as 2500-3000 ℃, which greatly increases the preparation difficulty of the material. In addition, once the existing electromagnetic shielding material is formed, the existing electromagnetic shielding material cannot be edited, remolded or recycled, has no inherent self-healing capability like a built-in biological repair system, is easily damaged within a period of time and often needs to be replaced from time to time, and any damage such as cut, crack and the like can cause the leakage of electromagnetic waves, thereby seriously affecting the electromagnetic shielding performance and the application safety and reliability of the material.

Therefore, the development of an electromagnetic shielding material with a self-repairing function has become a technical problem which needs to be solved by those skilled in the art.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an electromagnetic shielding material with a self-repairing function and a preparation method and application thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides an electromagnetic shielding material with a self-repairing function, wherein the electromagnetic shielding material is prepared from a combination of polyacrylic acid, calcium chloride, a water-soluble polymer, a carbon material and a water-soluble carbonate.

The raw materials for preparing the electromagnetic shielding material with the self-repairing function comprise a combination of polyacrylic acid, calcium chloride, a water-soluble polymer, a carbon material and a water-soluble carbonate, wherein the calcium chloride can react with the water-soluble carbonate to form amorphous calcium carbonate, the polyacrylic acid and the water-soluble polymer are jointly used as a matrix, the carbon material is dispersed in the matrix to form a conductive network, the material is endowed with excellent conductive performance, and finally the composite material with the excellent self-repairing function and the electromagnetic shielding performance is obtained.

Preferably, the polyacrylic acid has a molecular weight of 1000 to 100000g/mol, for example 2000g/mol, 5000g/mol, 7000g/mol, 10000g/mol, 30000g/mol, 50000g/mol, 70000g/mol or 90000g/mol, and more preferably 2000 to 5000 g/mol.

As a preferable technical scheme, the polyacrylic acid can obtain the electromagnetic shielding material with excellent performance only by keeping the molecular weight of the polyacrylic acid within the range of 1000-100000 g/mol; on the one hand, if the molecular weight of the polyacrylic acid is less than 1000g/mol, the polyacrylic acid has poor viscoelasticity and strong fluidity with the hydrogel formed by mineralization of amorphous calcium carbonate due to the short length of the polyacrylic acid chain, cannot keep a fixed shape or even form the hydrogel, and is easy to redisperse in water; on the other hand, if the molecular weight of the polyacrylic acid is higher than 100000g/mol, the chain length of the polyacrylic acid is too long, which results in poor binding property with amorphous calcium carbonate, poor binding force between polyacrylic acid molecules, severe pulverization of the formed hydrogel, no random deformation and remodeling, and loss of self-repairing function.

Preferably, the water-soluble polymer includes any one of polyvinyl alcohol, polyacrylamide, chitosan, carboxymethyl cellulose salt, carboxymethyl cellulose, alginate, methyl cellulose, gelatin, dextran, or agarose, or a combination of at least two thereof.

The mass ratio of the water-soluble polymer to the polyacrylic acid is preferably (0.1 to 10):100, for example, 0.3:100, 0.5:100, 0.7:100, 0.9:100, 1:100, 3:100, 5:100, 7:100, or 9:100, and more preferably (0.5 to 5): 100.

In the invention, as a preferable technical scheme, the mass ratio of the water-soluble polymer to the polyacrylic acid is required to be kept within the range of (0.1-10): 100, so that the obtained material has an excellent self-repairing function; on one hand, if too little water-soluble polymer is added, the viscoelastic performance for improving the polyacrylic acid and amorphous calcium carbonate cross-linked network is insufficient, the formed hydrogel has low viscosity and high fluidity, and the fixed shape cannot be kept; on the other hand, if too much water-soluble polymer is added, the cross-linked network of polyacrylic acid and calcium carbonate is easily damaged, so that the hydrogel is seriously pulverized, and the capability of random deformation and remodeling is lost, thereby the self-repairing function of the material is lost.

Preferably, the molar ratio of the calcium chloride to the polyacrylic acid is 1 (0.5-1.5), such as 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, or 1: 1.4.

Preferably, the carbon material includes any one of graphene, carbon nanotubes, carbon black, activated carbon, porous carbon, or a combination of at least two thereof, and is further preferably graphene.

The mass ratio of the carbon material to the polyacrylic acid is preferably (1-20): 100, for example, 2:100, 4:100, 6:100, 8:100, 10:100, 12:100, 14:100, 16:100, 18:100, and more preferably (1-10): 100.

According to the invention, as a preferable technical scheme, the material with excellent electromagnetic shielding performance and self-repairing function can be obtained only by keeping the mass ratio of the carbon material to the polyacrylic acid within the range of (1-20): 100; on one hand, when the content of the carbon material is low, an effective conductive network cannot be constructed in the matrix, the conductivity of the material is poor, and the electromagnetic shielding performance is low; when the amount of the carbon material is too much, the cross-linked network of polyacrylic acid, amorphous calcium carbonate and water-soluble polymer is easily destroyed by the excessive carbon material, so that the formed hydrogel is seriously pulverized, and the random deformation, remodeling and self-repairing functions are lost.

Preferably, the water-soluble carbonate includes any one or a combination of at least two of sodium carbonate, potassium carbonate, and ammonium carbonate, and is further preferably sodium carbonate.

In a second aspect, the present invention provides a method for preparing the electromagnetic shielding material according to the first aspect, the method comprising the steps of:

(1) dispersing polyacrylic acid, calcium chloride, water-soluble polymer and carbon material in water to obtain a mixed solution;

(2) and (2) adding an aqueous solution of water-soluble carbonate into the mixed solution obtained in the step (1) for reaction to obtain the electromagnetic shielding material.

The preparation method of the electromagnetic shielding material provided by the invention is simple, convenient and feasible and can be used for large-scale batch production.

Preferably, the amount of the polyacrylic acid is 0.01 to 1mol, for example, 0.03mol, 0.05mol, 0.09mol, 0.1mol, 0.2mol, 0.3mol, 0.4mol, 0.5mol, 0.6mol, 0.7mol, 0.8mol, or 0.9mol, and more preferably 0.05 to 0.5mol, based on 1L of the mixed solution in the step (1).

Preferably, the number of moles of the water-soluble carbonate is 0.1 to 1mol, for example, 0.2mol, 0.3mol, 0.4mol, 0.5mol, 0.6mol, 0.7mol, 0.8mol or 0.9mol, and more preferably 0.2 to 0.5mol, based on 1L of the aqueous solution of the water-soluble carbonate in the step (2).

Preferably, the adding method in the step (2) is dropwise adding.

Preferably, the reaction of step (2) is further followed by a washing step.

Preferably, the washing comprises a deionized water washing.

In a third aspect, the present invention provides a use of the electromagnetic shielding material according to the first aspect in an electronic device.

Compared with the prior art, the invention has the following beneficial effects:

(1) the raw materials for preparing the electromagnetic shielding material with the self-repairing function comprise a combination of polyacrylic acid, calcium chloride, a water-soluble polymer, a carbon material and a water-soluble carbonate, wherein the calcium chloride can generate amorphous calcium carbonate with the water-soluble carbonate, the polyacrylic acid, the amorphous calcium carbonate and the water-soluble polymer are used as matrixes for the electromagnetic shielding material to obtain hydrogel, the carbon material is dispersed in the hydrogel, and the electromagnetic shielding material has excellent electromagnetic shielding performance while the capability of randomly stretching, deforming, reshaping and recycling is ensured;

(2) the preparation method of the electromagnetic shielding material with the self-repairing function provided by the invention has high production efficiency, is simple, convenient and feasible, can be applied in a large-scale amplification way, uses nontoxic and harmless raw materials, does not use toxic and harmful chemical reagents, does not generate waste water, and meets the requirements of environmental protection.

Drawings

Fig. 1 is an outline view of an electromagnetic shielding material with a self-repairing function obtained in example 1 in a normal state;

fig. 2 is an outline view of the electromagnetic shielding material with self-repairing function obtained in example 1 before it is manually stretched;

fig. 3 is an outline view of the electromagnetic shielding material with self-repairing function obtained in example 1 after being manually stretched;

fig. 4 is a separated shape view of the electromagnetic shielding material with self-repairing function obtained in example 1;

fig. 5 is a drawing showing the tensile shape of the electromagnetic shielding material having the self-repairing function obtained in example 1 after the separation and the contact recovery for 1 second.

Detailed Description

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

An electromagnetic shielding material with a self-repairing function is prepared by the following steps:

(1) dispersing polyacrylic acid, calcium chloride, chitosan and graphene powder with the molecular weight of 3000g/mol in water, and uniformly stirring to obtain a mixed solution, wherein the concentration of the polyacrylic acid is 0.2mol/L, the concentration of the calcium chloride is 0.2mol/L, the mass ratio of the chitosan to the polyacrylic acid is 2:100, the mass ratio of the graphene powder to the polyacrylic acid is 5:100, and the molar ratio of the calcium chloride to the polyacrylic acid is 1: 1;

(2) and (2) dropwise adding an aqueous solution of sodium carbonate with the concentration of 0.5mol/L into the mixed solution obtained in the step (1), and carrying out a violent stirring reaction to obtain the electromagnetic shielding material.

Example 2

An electromagnetic shielding material having a self-repairing function is different from example 1 only in that a carbon nanotube powder is used instead of the graphene powder in step (1) of example 1, and other components, amounts and steps are the same as those of example 1.

Example 3

An electromagnetic shielding material having a self-repairing function is different from example 1 only in that carbon black powder is used instead of the graphene powder in step (1) of example 1, and other components, amounts and steps are the same as those of example 1.

Example 4

An electromagnetic shielding material with a self-repairing function is different from the embodiment 1 only in that the mass ratio of graphene powder to polyacrylic acid in the step (1) is 1:100, and other components, the using amount and the steps are the same as those in the embodiment 1.

Example 5

An electromagnetic shielding material with a self-repairing function is different from the embodiment 1 only in that the mass ratio of graphene powder to polyacrylic acid in the step (1) is 7:100, and other components, the using amount and the steps are the same as those in the embodiment 1.

Example 6

An electromagnetic shielding material having a self-repairing function, which is different from example 1 only in that polyvinyl alcohol is used instead of chitosan in step (1) of example 1, and other components, amounts and steps are the same as those of example 1.

Example 7

An electromagnetic shielding material with a self-repairing function is different from the embodiment 1 only in that the mass ratio of graphene powder to polyacrylic acid in the step (1) is 20:100, and other components, the using amount and the steps are the same as those in the embodiment 1.

Example 8

An electromagnetic shielding material with a self-repairing function is different from the embodiment 1 only in that the mass ratio of the graphene powder to the polyacrylic acid in the step (1) is 30:100, and other components, the using amount and the steps are the same as those in the embodiment 1.

Example 9

An electromagnetic shielding material having a self-repairing function is different from example 1 only in that the mass ratio of graphene powder to polyacrylic acid in step (1) is 0.8:100, and other components, amounts and steps are the same as those of example 1.

Example 10

An electromagnetic shielding material with a self-repairing function is different from the embodiment 1 only in that the mass ratio of chitosan to polyacrylic acid in the step (1) is 10:100, and other components, the using amount and the steps are the same as those in the embodiment 1.

Example 11

An electromagnetic shielding material having a self-repairing function is different from example 1 only in that the mass ratio of chitosan to polyacrylic acid in step (1) is 0.1:100, and other components, amounts and steps are the same as those of example 1.

Example 12

An electromagnetic shielding material with a self-repairing function is different from the embodiment 1 only in that the mass ratio of chitosan to polyacrylic acid in the step (1) is 25:100, and other components, the using amount and the steps are the same as those in the embodiment 1.

Example 13

An electromagnetic shielding material having a self-repairing function is different from example 1 only in that the mass ratio of chitosan to polyacrylic acid in step (1) is 0.05:100, and other components, amounts and steps are the same as those of example 1.

Example 14

An electromagnetic shielding material having a self-repairing function, which is different from example 1 only in that the molecular weight of polyacrylic acid in step (1) is 500g/mol, and the other components, amounts and steps are the same as those of example 1.

Example 15

An electromagnetic shielding material having a self-repairing function, which is different from example 1 only in that polyacrylic acid in step (1) has a molecular weight of 100500g/mol, and the other components, amounts and steps are the same as those of example 1.

Comparative example 1

An electromagnetic shielding material having a self-repairing function is different from example 1 only in that a carbon material is not added in step (1), and other components, amounts and steps are the same as those of example 1.

And (3) performance testing:

(1) the appearance is as follows: and observing the stretched shape of the prepared material by naked eyes in a normal state, before and after manual stretching, after the material is divided into two halves, and after the material is divided into two halves, the material is contacted and recovered for 1 s.

The electromagnetic shielding material with the self-repairing function obtained in the example 1 is tested according to the testing method (1), and the outline of the electromagnetic shielding material with the self-repairing function obtained in the example 1 in a normal state is shown in fig. 1, and as can be seen from fig. 1, the electromagnetic shielding material obtained in the example 1 can keep a fixed shape without support; the shape diagrams of the electromagnetic shielding material with the self-repairing function obtained in example 1 before and after being manually stretched are shown in fig. 2 and 3, respectively, and it can be seen from fig. 2 and 3 that the electromagnetic shielding material obtained in example 1 can be arbitrarily stretched and deformed without being broken; the tensile shape diagrams of the electromagnetic shielding material with the self-repairing function obtained in example 1 after being divided into two halves and after being contacted again and recovered for 1s are shown in fig. 4 and 5, respectively, and it can be seen from fig. 4 and 5 that the electromagnetic shielding material obtained in example 1 can be rapidly self-repaired.

(2) Electromagnetic shielding performance: measuring the electromagnetic shielding material with the thickness of 9mm on a vector network analyzer by adopting a waveguide method, wherein the frequency range of electromagnetic waves is 8.2-12.4 GHz (X-waveband);

the electromagnetic shielding materials obtained in examples 1 to 15 and comparative example 1 were tested according to the above test method, and the test results are shown in table 1:

TABLE 1

As can be seen from the data in table 1:

the electromagnetic shielding materials obtained in the embodiments 1 to 7 can keep a fixed shape in a normal state, cannot be broken after being stretched, and can be recovered by being divided into two halves and then being contacted for 1 s; the electromagnetic shielding performance can reach 70-140 dB.

Comparing example 1 with comparative example 1, it can be seen that the electromagnetic shielding performance of the material prepared without adding the carbon material was only 20 dB.

Further comparing the embodiment 1 with the embodiments 7 to 9, it can be found that the electromagnetic shielding material obtained in the embodiment 8 is pulverized, broken after stretching, and not easy to recover after breaking, which proves that the self-repairing performance of the material is reduced due to excessive addition of the carbon material, and the electromagnetic shielding performance of the material obtained in the embodiment 9 is 50dB, which indicates that the electromagnetic shielding performance of the finally obtained material is reduced due to low use amount of the carbon material.

Further comparing the example 1 with the examples 10 to 13, it can be found that too much chitosan (example 12) can also cause the self-repairing performance of the material to be reduced; too little chitosan addition (example 13) results in the shape of the material not being fixed and the electromagnetic shielding performance of the material being reduced.

Further comparing the examples 1 and 14 to 15, it can be found that the self-repairing performance and the electromagnetic shielding performance of the finally obtained material are affected by the too high or too low molecular weight of the polyacrylic acid.

The applicant states that the present invention describes an electromagnetic shielding material with self-repairing function and its preparation method and application by the above embodiments, but the present invention is not limited to the above process steps, i.e. it does not mean that the present invention must rely on the above process steps to be implemented. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.