CN111511181B - A patterned electromagnetic shielding material and its preparation method and application - Google Patents

Abstract

The present invention provides a patterned electromagnetic shielding material, a preparation method and application thereof, including a patterned electromagnetic shielding layer, wherein the components of the patterned electromagnetic shielding layer include conductive fillers and a resin substrate; wherein, the patterned electromagnetic shielding layer The porosity of the shielding layer is 10‑90%. The patterned electromagnetic shielding material provided by the present invention has excellent electrical conductivity and stretchability, and has good light transmittance and high electromagnetic shielding efficiency.

Description

A patterned electromagnetic shielding material and its preparation method and application

technical field

The invention belongs to the technical field of electromagnetic shielding materials, and relates to a patterned electromagnetic shielding material and a preparation method and application thereof, in particular to a stretchable patterned electromagnetic shielding material, a preparation method and application thereof.

Background technique

With the wide application of electronic and wireless communication devices in life and production, electromagnetic radiation and electromagnetic interference have become important factors that affect the normal operation of electronic devices, and are also new sources of pollution that endanger human health. In order to reduce or avoid the phenomenon of electromagnetic interference, it is becoming more and more important to protect electronic devices and human health by using the principle of electromagnetic shielding. At present, advanced precision electronic equipment has been widely used in defense and military, medical and health, industrial production and other fields, including radar display, navigation system, precision instrument, touch screen and other electronic equipment observation windows need to use transparent electromagnetic shielding materials. Because the transparent electromagnetic shielding material requires both high light transmittance and high electromagnetic shielding efficiency in practical applications, it brings huge difficulties to the research and application of the transparent electromagnetic shielding material system.

At present, transparent electromagnetic shielding materials generally use metal mesh structure as shielding layer, including metal materials such as nickel, copper, stainless steel, etc. The transparent electromagnetic shielding materials of these metal mesh structures are usually rigid and can only bend and deform, but cannot achieve tensile deformation. , and is susceptible to corrosion and failure due to the influence of the external environment. The development and application of flexible electronic devices requires electromagnetic shielding materials to have a certain degree of stretchability; metal grid transparent electromagnetic shielding materials cannot be directly applied because they cannot meet the large deformation requirements of flexible electronic devices and flexible integrated circuits.

CN102291971A discloses a flexible lighting electromagnetic shielding window, which includes a flexible metal mesh, a flexible metal shielding cloth frame is superimposed around the metal mesh, and flexible transparent films are laminated on both sides of the metal mesh. The electromagnetic shielding window provided by the patent application can be It can solve the problem of light transmittance of electromagnetic shielding materials to a certain extent, but it cannot be applied to some electromagnetic shielding fields with strict requirements on materials, the application scope is narrow, and the cost is high. CN102848610A discloses an electromagnetic shielding material, which includes a base material layer and a metal wire mesh fused in the base material layer, the base material layer is made of a material that is flexible and has an electromagnetic shielding function, and the The metal wire mesh is woven into a grid shape by a plurality of metal wires, and the base material layer is made of one or more of polyethylene, polyester, nylon, and polyvinyl chloride. Although the electromagnetic shielding material provided in this patent application has good light transmittance, it ensures the light transmittance on the premise of losing the electromagnetic shielding performance, which is not conducive to practical application.

Therefore, there is a need to provide an electromagnetic shielding material that can take into account light transmittance, electromagnetic shielding effectiveness and tensile properties at the same time.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a patterned electromagnetic shielding material and a preparation method and application thereof. The patterned electromagnetic shielding material provided by the present invention has excellent electrical conductivity and stretchability, and has good light transmittance. The electromagnetic shielding efficiency is high.

In order to achieve this object of the invention, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a patterned electromagnetic shielding material, comprising a patterned electromagnetic shielding layer, and the composition of the patterned electromagnetic shielding layer includes a conductive filler and a resin substrate.

Wherein, the porosity of the patterned electromagnetic shielding layer is 10-90%, such as 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc.

The present invention specifically selects a patterned electromagnetic shielding layer with a porosity of 10-90%. Within this range, the patterned electromagnetic shielding layer has both high electromagnetic shielding efficiency and good light transmittance; If the porosity is too large, the electromagnetic shielding effect will be small; if the porosity is small, the light transmittance of the electromagnetic shielding layer will be poor.

In the present invention, the patterned electromagnetic shielding layer has through holes, and the porosity refers to the percentage of the volume of the through holes to the total volume of the patterned electromagnetic shielding layer.

Preferably, the patterned electromagnetic shielding layer has polygonal through holes and/or circular through holes. The present invention refers to the through hole having a polygonal structure and/or a circular structure.

Preferably, the patterned electromagnetic shielding layer has at least two polygonal through holes and/or circular through holes arranged in an array.

The polygons described in the present invention include regular polygons and irregular polygons. Exemplarily, regular polygons include triangles, rectangles, squares, pentagons, hexagons, etc.; irregular polygons mean that at least one side is an arc , wavy lines, curves and other irregular shapes, such as sectors, are collectively referred to as polygons in the present invention.

In the present invention, the maximum size of the polygonal through hole and/or the circular through hole is 50-2000 μm, such as 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1200 μm, 1500 μm, 1800 μm, 1900 μm, etc.

In the present invention, the maximum size refers to the maximum length of a line connecting any two points in the polygonal through hole and/or circular through hole, for example, the maximum size of a circle is the diameter, and the maximum size of a square is the diameter. The maximum size is the diagonal length, etc.

Preferably, the distance between the centers of any two adjacent circular through holes is 50-500 μm, such as 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, and the like.

Preferably, the distance between the centers of any two adjacent polygonal through holes is 50-2000 μm, such as 100 μm, 200 μm, 500 μm, 800 μm, 1000 μm, 1200 μm, 1500 μm, 1800 μm, 1900 μm and so on.

Preferably, the line width of the polygonal through hole and/or the circular through hole is 10-500 μm, such as 20 μm, 50 μm, 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, etc.

In the present invention, the line width of the polygonal through hole and/or the circular through hole refers to the width of the side length of the polygonal through hole and/or the circular through hole, and the side length may be the same width, for example, The shape of the through hole is square; it can also be of different widths, for example, when the shape of the through hole is an irregular polygon or a round hole. The present invention only needs to ensure that the line widths of all side lengths are within the scope of the present invention.

In the present invention, the conductive fillers are selected from metal fillers and/or carbon material-based fillers.

Preferably, the metal filler is selected from any one or a combination of at least two of silver powder, copper powder, nickel powder, iron powder, aluminum powder, zinc powder or tin powder.

Preferably, the carbon material-based filler is selected from any one or a combination of at least two of graphite, graphene, carbon fiber, carbon black or carbon nanotubes.

Preferably, the resin substrate is selected from polyurethane, silicone rubber, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate, polyimide or poly-3,4-ethylenedioxythiophene/ Any one or a combination of at least two polystyrene sulfonates, more preferably in polyurethane, silicone rubber, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate or polyimide any one or a combination of at least two.

The present invention uses metal fillers or carbon-based fillers as conductive components, and uses flexible polymer materials as substrates to prepare polymer conductive composite materials, which are prepared into patterned electromagnetic shielding layers by techniques such as printing and deposition. The stretchability of the shielding layer can improve the corrosion resistance of the material, and maintain high electrical conductivity and electromagnetic shielding performance. Optical requirements and electromagnetic shielding requirements for flexible electronics.

Preferably, based on the total mass of the patterned electromagnetic shielding material, the content of the conductive filler is 20-90%, such as 30%, 40%, 50%, 60%, 70%, 80%, etc.

Preferably, the conductive filler is a metal filler, and the content of the conductive filler is 85% based on the total mass of the patterned electromagnetic shielding material.

Preferably, the conductive filler is a carbon black filler, and the content of the conductive filler is 30% based on the total mass of the patterned electromagnetic shielding material.

Preferably, the conductive filler is carbon fiber and/or carbon nanotube, and the content of the conductive filler is 40% based on the total mass of the patterned electromagnetic shielding material.

Preferably, it also includes a flexible base layer disposed on one side of the patterned electromagnetic shielding layer.

Preferably, the composition of the flexible base layer comprises polydimethylsiloxane, polyurethane, silicone rubber, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate or polyimide any one or a combination of at least two.

Preferably, the thickness of the patterned electromagnetic shielding layer is 5-100 μm, such as 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm and the like.

Preferably, the thickness of the flexible base layer is 10-200 μm, such as 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm and the like.

The electromagnetic shielding layer provided by the present invention can be bonded with the substrate through chemical cross-linking, hot melting, solvent dissolution, etc., thereby ensuring that the electromagnetic shielding material of the present invention has both good electromagnetic shielding performance and good mechanical properties. performance and stretchability.

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

The electromagnetic shielding paste is placed on the flexible substrate, and then the flexible substrate is removed to obtain the patterned electromagnetic shielding layer.

Wherein, the porosity of the patterned electromagnetic shielding layer is 10-90%, such as 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, etc.

Preferably, the means of setting comprises screen printing, fused direct writing, ink jet printing or fused deposition.

In a third aspect, the present invention provides the application of the patterned electromagnetic shielding material according to the first aspect in radar display, navigation system, precision instrument or touch screen.

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

(1) The patterned electromagnetic shielding material provided by the present invention has excellent electrical conductivity and stretchability, as well as good light transmittance and high electromagnetic shielding efficiency.

(2) The present invention can adjust the final patterned electromagnetic shielding material by adjusting the patterned structure (including square, hexagonal, circular, wavy, etc.) and adjusting the conductivity, line width, thickness, etc. of the conductive polymer composite material. The light transmittance and electromagnetic shielding efficiency are 15%-60%, and the electromagnetic shielding efficiency is 15-45dB, which can meet the application requirements of electromagnetic shielding windows and flexible electromagnetic shielding materials.

Description of drawings

FIG. 1 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in Embodiment 1. FIG.

FIG. 2 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in Embodiment 2. FIG.

FIG. 3 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in Embodiment 3. FIG.

FIG. 4 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in Example 4. FIG.

FIG. 5 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in Example 13. FIG.

FIG. 6 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in Comparative Example 1. FIG.

Detailed ways

The technical solutions of the present invention are further described below through specific embodiments. It should be understood by those skilled in the art that the embodiments are only for helping the understanding of the present invention, and should not be regarded as a specific limitation of the present invention.

Example 1

A patterned electromagnetic shielding material is composed of a patterned electromagnetic shielding layer and a flexible base layer;

1 is a schematic diagram of the structure of the patterned electromagnetic shielding layer. As shown in FIG. 1 , the patterned electromagnetic shielding layer has periodically arranged polygonal through holes composed of four curves, and the maximum size of the polygon is 480 μm.

The pattern of the patterned electromagnetic shielding layer consists of circles and curves, the diameter of the circle is 200 μm, and the line width of the wavy line is 50 μm.

The preparation method is as follows:

(1) Preparation of flexible base layer

The quartz glass was placed on a spin coater, and then a thermoplastic polyurethane (BASF Elastollan 1185A)/N,N-dimethylformamide solution (TPU/DMF) with a mass fraction of 25 wt% was poured on the quartz glass at 800 rpm. The coating film was rotated at a rotational speed for 10 s, and the coated quartz glass was placed in a blast oven at 75° C. for 30 min to obtain a thermoplastic polyurethane base layer.

(2) Preparation of electromagnetic shielding materials

The 25wt% TPU/DMF solution provided in step (1) is mixed with flaky silver powder (medium color Dongfang) to obtain electromagnetic shielding paste, wherein the mass ratio of TPU to flaky silver powder is 15:85;

The thermoplastic polyurethane base layer was placed on the screen printing table, the patterned electromagnetic shielding material was screen printed on the screen printing table, and placed in an oven at 75°C for 2 hours after printing to obtain the patterned electromagnetic shielding material.

Example 2

The difference from Example 1 is that in the screen printing process, the screen plates with different patterns are replaced to obtain patterned electromagnetic shielding materials with different patterns.

FIG. 2 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in this embodiment. As shown in FIG. 2 , the patterned electromagnetic shielding layer has square through holes with a maximum size of 700 μm and a line width of 500 μm.

Example 3

The difference from Example 1 is that in the screen printing process, the screen plates with different patterns are replaced to obtain patterned electromagnetic shielding materials with different patterns.

FIG. 3 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in this embodiment. As shown in FIG. 3 , the patterned electromagnetic shielding layer has circular through holes with a maximum size of 1000 μm and a line width of 500 μm.

Example 4

The difference from Example 1 is that in the screen printing process, the screen plates with different patterns are replaced to obtain patterned electromagnetic shielding materials with different patterns.

FIG. 4 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in this embodiment. As shown in FIG. 4 , the patterned electromagnetic shielding layer has hexagonal through holes with a maximum size of 1000 μm and a line width of 500 μm.

Examples 5-8

A patterned electromagnetic shielding material is composed of a patterned electromagnetic shielding layer and a flexible base layer;

Among them, the patterns refer to Examples 1-4.

The preparation method is as follows:

(1) Preparation of flexible base layer

Put the quartz glass on the spin coater, then pour the polydimethylsiloxane precursor solution (PDMS, Sylgard184) on the quartz glass, spin the coating film at 600rpm for 15s, and place the coated quartz glass on the glass. In an oven at 60°C for 30min, a semi-cured PDMS film was obtained;

(2) Preparation of electromagnetic shielding materials

Same as Example 1.

Examples 9-12

A patterned electromagnetic shielding material is composed of a patterned electromagnetic shielding layer and a flexible base layer;

Among them, the patterns refer to Examples 1-4.

The preparation method is as follows:

(1) Preparation of flexible base layer

Polyethylene (LDPE, C7100, Asia Polymer Corporation) melt was formed into a film by extrusion casting to obtain a polyethylene flexible base film with a thickness of 60 μm;

(2) Preparation of electromagnetic shielding materials

Slurry Reference Example 1

The polyethylene flexible substrate is placed in a fused deposition printer to perform fused deposition of the patterned electromagnetic shielding material, and cooled to room temperature to obtain the patterned electromagnetic shielding material.

Example 13

A patterned electromagnetic shielding material is composed of a patterned electromagnetic shielding layer and a flexible base layer;

5 is a schematic structural diagram of the patterned electromagnetic shielding layer. As shown in FIG. 5 , the patterned electromagnetic shielding layer has periodically arranged square through holes with a maximum size of 1.0 mm and a line width of 50 μm.

The preparation method is as follows:

(1) Preparation of flexible base layer

With reference to embodiment 1, it is identical with embodiment 1;

(2) Preparation of electromagnetic shielding materials

The nickel powder, poly-3,4-ethylenedioxythiophene/polystyrene sulfonate (PEDOT:PSS), and wetting agent are prepared into ink according to the mass ratio of 6:10:3;

The patterned electromagnetic shielding layer is printed by inkjet printing to obtain a patterned electromagnetic shielding material.

Example 14

A patterned electromagnetic shielding material is composed of a patterned electromagnetic shielding layer and a flexible base layer;

The pattern refers to Example 13.

The preparation method is as follows:

(1) Preparation of flexible base layer

Flexible base layer reference example 1

(2) Preparation of electromagnetic shielding materials

The carbon nanotubes and water-based polyurethane (Chengdu Organic Chemicals Co.LTD) were prepared into ink according to the mass ratio of 1:4;

The patterned electromagnetic shielding layer is printed by inkjet printing to obtain a patterned electromagnetic shielding material.

Comparative Example 1

The difference from Example 2 is that in the screen printing process, the screen plates with different patterns are replaced to obtain patterned electromagnetic shielding materials with different patterns.

FIG. 6 is a schematic structural diagram of the patterned electromagnetic shielding layer provided in this embodiment. As shown in FIG. 6 , the patterned electromagnetic shielding layer has square through holes with a maximum size of 2.4 mm and a line width of 1000 μm.

Performance Testing

The electromagnetic shielding materials provided in Examples 1-14 and Comparative Example 1 were tested for performance, and the methods were as follows:

(1) light transmittance: adopt an ultraviolet-visible photometer (Shimadzu Corporation, UV-3600) to measure the light transmittance in the wavelength range of 400-800nm, and use the light transmittance at 550nm as the light transmittance of the electromagnetic shielding material;

(2) Electromagnetic shielding effectiveness: Use a vector network analyzer (VNA, Keysight, E5071C) to measure the electromagnetic shielding effectiveness in the 8.2-12.5GHz frequency band;

The test results are shown in Table 1:

Table 1

It can be seen from the examples and performance tests that the patterned electromagnetic shielding material provided by the present invention has better light transmittance and better electromagnetic shielding efficiency, and can meet application requirements, wherein the light transmittance is 15%-60% , the electromagnetic shielding efficiency is 15-45dB, which can meet the application requirements of electromagnetic shielding windows and flexible electromagnetic shielding materials.

It can be seen from the comparison between the examples and the comparative examples that the patterned electromagnetic shielding material provided by the present invention takes into account both the light transmittance and the electromagnetic shielding efficiency, and balances the two performances.

The applicant declares that the present invention is to illustrate the patterned electromagnetic shielding material of the present invention and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be able to implement. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of the selected raw materials of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims (9)

1. A patterned electromagnetic shielding material, characterized in that it comprises a patterned electromagnetic shielding layer, and the composition of the patterned electromagnetic shielding layer comprises a conductive filler and a resin base material; Wherein, the porosity of the patterned electromagnetic shielding layer is 10-29%; The patterned electromagnetic shielding material is prepared by a method comprising the following steps: disposing the electromagnetic shielding paste on the flexible substrate, and then removing the flexible substrate to obtain the patterned electromagnetic shielding layer; The electromagnetic shielding paste is mainly prepared by mixing conductive fillers and resin substrates; The patterned electromagnetic shielding layer has at least two polygonal through holes and/or circular through holes arranged in an array; The maximum size of the polygonal through hole and/or the circular through hole is 50-2000 μm; The distance between the centers of any two adjacent circular through holes is selected from 50-500 μm; The distance between the centers of any two adjacent polygonal through holes is selected from 50-2000 μm; The line width of the polygonal through hole and/or the circular through hole is 10-500 μm; The conductive filler is selected from metal fillers and/or carbon material fillers; The metal filler is selected from any one or a combination of at least two of silver powder, copper powder, nickel powder, iron powder, aluminum powder, zinc powder or tin powder; The carbon material-based filler is selected from any one or a combination of at least two of graphite, graphene, carbon fiber, carbon black or carbon nanotubes; Based on the total mass of the patterned electromagnetic shielding material, the content of the conductive filler is 20-90%; The conductive filler is a metal filler, and the content of the conductive filler is 85% based on the total mass of the patterned electromagnetic shielding material; The conductive filler is a carbon black filler, and the content of the conductive filler is 30% based on the total mass of the patterned electromagnetic shielding material; The conductive filler is carbon fiber and/or carbon nanotube, and the content of the conductive filler is 40% based on the total mass of the patterned electromagnetic shielding material. 2. The patterned electromagnetic shielding material according to claim 1, wherein the resin substrate is selected from the group consisting of polyurethane, silicone rubber, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate , polyimide or poly-3,4-ethylenedioxythiophene/polystyrene sulfonate any one or a combination of at least two. 3. The patterned electromagnetic shielding material according to claim 2, wherein the resin substrate is selected from the group consisting of polyurethane, silicone rubber, polyethylene terephthalate, polyethylene, polypropylene, polycarbonate Or any one of polyimide or a combination of at least two. 4. The patterned electromagnetic shielding material according to claim 1, further comprising a flexible base layer disposed on one side of the patterned electromagnetic shielding layer. 5 . The patterned electromagnetic shielding material according to claim 4 , wherein the composition of the flexible base layer comprises polyurethane, silicone rubber, polyethylene terephthalate, polyethylene, polypropylene, polyethylene Either one or a combination of at least two of carbonate or polyimide. 6 . The patterned electromagnetic shielding material according to claim 1 , wherein the thickness of the patterned electromagnetic shielding layer is 5-100 μm. 7 . 7 . The patterned electromagnetic shielding material according to claim 4 , wherein the thickness of the flexible base layer is 10-200 μm. 8 . 8 . The patterned electromagnetic shielding material according to claim 1 , wherein the setting method comprises screen printing, fused direct writing, ink jet printing or fused deposition. 9 . 9. Application of the patterned electromagnetic shielding material according to any one of claims 1 to 8 in radar displays, navigation systems, precision instruments or touch screens.

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