Super-hydrophobic electromagnetic shielding paper as well as preparation method and application thereof

Abstract

The invention provides super-hydrophobic electromagnetic shielding paper as well as a preparation method and application thereof. The preparation method comprises the following steps: dispersing carbon fibers, metallized glass fibers and glass fibers in water, and uniformly stirring to obtain fiber slurry; the mass ratio of the carbon fiber to the metallized glass fiber to the glass fiber is (0.1-0.4): (0.1-0.4): 1; naturally settling, squeezing and drying the fiber pulp to obtain first shielding paper of which the density is in gradient distribution; and applying a resin adhesive to the first shielding paper, and drying to obtain the super-hydrophobic electromagnetic shielding paper. The technical problem to be solved by the invention is how to prepare the super-hydrophobic electromagnetic shielding paper, so that the super-hydrophobic electromagnetic shielding paper has relatively high shielding performance (the average shielding effectiveness of 8-12.4 GHz is greater than or equal to 25dB), the shielding performance can be kept for a long time, and the service life is long. And meanwhile, the composite material also has relatively high mechanical strength (the tensile strength is greater than or equal to 9N / 15mm) and good hydrophobicity (the hydrophobic angle is greater than or equal to 147 degrees).

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic shielding materials, and in particular to a super-hydrophobic electromagnetic shielding paper and a preparation method and application thereof. Background Art

[0002] With the rapid development of communication technology and the extensive use of electronic equipment, electromagnetic waves have brought convenience to people, but at the same time have certain effects on the human body and precision electronic devices. Therefore, electromagnetic shielding materials have become one of the indispensable materials in production and life.

[0003] In the prior art, electromagnetic shielding paper is mainly composed of metal-based fibers, metal particles, carbon-based fibers, carbon particles or several mixed materials and plant fibers. For example, there are literature reports that plant fibers are used as skeleton fibers, and nickel powder, silicon carbide and ferrite / glass fibers are filled into the skeleton fibers; there are also literature reports that short-cut carbon fibers and plant fibers are mixed for papermaking; there are also literature reports that wood cellulose nanofibers and plant fibers with surface-modified MXene are mixed for papermaking. However, the shielding strength of the above-mentioned electromagnetic shielding paper is low, and the shielding performance is easy to fail, and the shielding paper may face some pulling forces during use, and the current shielding paper has relatively low mechanical properties and is easy to break during use. The above defects result in a short service life of the electromagnetic shielding paper in the prior art and unsatisfactory use effect. Summary of the invention

[0004] The main purpose of the present invention is to provide a super-hydrophobic electromagnetic shielding paper and a preparation method and application thereof. The technical problem to be solved is how to prepare a super-hydrophobic electromagnetic shielding paper so that it has high shielding performance (average shielding effectiveness ≥25dB ​​from 8 to 12.4GHz) and the shielding performance can be maintained for a long time and has a long service life; at the same time, it also has high mechanical strength (tensile strength ≥9N / 15mm) and good hydrophobicity (hydrophobic angle ≥147°), so that it is more suitable for practical use.

[0005] The purpose of the present invention and the technical problem solved are achieved by adopting the following technical solutions. According to a method for preparing super hydrophobic electromagnetic shielding paper proposed in the present invention, the method comprises the following steps:

[0006] S11 disperses carbon fiber, metal-plated glass fiber and glass fiber in water, and stirs evenly to obtain fiber slurry; wherein the mass ratio of the carbon fiber, metal-plated glass fiber and glass fiber is 0.1-0.4:0.1-0.4:1;

[0007] S12: naturally settling the fiber slurry, pressing and drying it to obtain a first shielding paper with a gradient density distribution;

[0008] S13: applying a resin adhesive on the surface of the first shielding paper and drying it to obtain a super-hydrophobic electromagnetic shielding paper.

[0009] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0010] Preferably, in the aforementioned preparation method, the steps of preparing the fiber slurry are as follows:

[0011] S21 disperses the carbon fiber and the first glass fiber in water and stirs them evenly to obtain a pre-entangled fiber slurry; wherein the mass ratio of the carbon fiber to the first glass fiber is 0.2 to 0.9:1;

[0012] S22 disperses the metal-plated glass fiber, the second glass fiber and the pre-entangled fiber slurry in water, stirs evenly, and obtains fiber slurry; wherein the mass ratio of the metal-plated glass fiber to the second glass fiber is 0.2 to 0.9:1; the ratio of the sum of the mass of the carbon fiber and the first glass fiber to the sum of the mass of the metal-plated glass fiber and the second glass fiber is 0.2 to 1:1.

[0013] Preferably, in the aforementioned preparation method, the mass ratio of the carbon fiber to the metal-plated glass fiber is 0.6-1.7:1; the mass ratio of the sum of the carbon fiber and the metal-plated glass fiber to the glass fiber is 0.35-0.70:1.

[0014] Preferably, in the aforementioned preparation method, the fiber diameter of the first glass fiber is ≤0.5 μm; the fiber diameter of the second glass fiber is ≤1.5 μm; and the diameter of the metal-plated glass fiber is ≤5 μm.

[0015] Preferably, in the aforementioned preparation method, the step of applying a resin adhesive on the surface of the first shielding paper is as follows:

[0016] S51: soaking the first shielding paper in a deionized water solution of acrylic resin for ≤1 min to obtain a second shielding paper;

[0017] S52: spraying the ethanol solution of fluoroalkylsilane onto the second shielding paper.

[0018] The purpose of the present invention and the technical problem to be solved are achieved by adopting the following technical solutions. A super hydrophobic electromagnetic shielding paper proposed in the present invention comprises:

[0019] Metallized fiberglass layer;

[0020] a glass fiber layer disposed adjacent to the metallized glass fiber layer;

[0021] A carbon fiber layer is arranged adjacent to the glass fiber layer; the glass fibers on one side surface of the glass fiber layer are interspersed into the carbon fiber layer and entangled with the carbon fibers, and the glass fibers on the other side surface are interspersed into the metal-plated glass fiber layer and entangled with the metal-plated glass fibers; along the thickness direction of the super-hydrophobic electromagnetic shielding paper, the metal-plated glass fiber layer, the glass fiber layer and the carbon fiber layer are a density gradient structure; the metal-plated glass fiber layer, the glass fiber layer and the carbon fiber layer are bonded by a resin adhesive.

[0022] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0023] Preferably, the aforementioned super hydrophobic electromagnetic shielding paper has a tensile strength ≥9N / 15mm, an average shielding effectiveness ≥25dB ​​at 8-12.4GHz, and a hydrophobic angle ≥147°.

[0024] Preferably, the aforementioned super-hydrophobic electromagnetic shielding paper further comprises:

[0025] The non-woven fabric layer is arranged on both sides of the super-hydrophobic electromagnetic shielding paper and is respectively bonded to the metal-plated glass fiber layer and the carbon fiber layer through the resin adhesive.

[0026] Preferably, the aforementioned super-hydrophobic electromagnetic shielding paper is prepared according to the aforementioned preparation method.

[0027] The purpose of the present invention and the technical problem to be solved are achieved by adopting the following technical solutions: According to the present invention, an application of the aforementioned super-hydrophobic electromagnetic shielding paper in the field of electromagnetic shielding materials is proposed.

[0028] By means of the above technical solution, the super-hydrophobic electromagnetic shielding paper and its preparation method and application proposed by the present invention have at least the following advantages:

[0029] The super-hydrophobic electromagnetic shielding paper and its preparation method and application proposed in the present invention are prepared into fiber slurry by reasonably proportioning carbon fiber, metal-plated glass fiber and glass fiber, and then the fiber slurry is naturally settled to form a shielding paper with a gradient density distribution, and then various fibers are bonded together by a resin adhesive to obtain the super-hydrophobic electromagnetic shielding paper of the present invention; the super-hydrophobic electromagnetic shielding paper obtained by the technical scheme of the present invention has good comprehensive performance, and has high shielding performance, and its average shielding effectiveness at 8-12.4GHz is ≥25dB; when aluminum-plated glass fiber is further preferred as the metal-plated glass fiber, its average shielding effectiveness at 8-12.4GHz is further improved to ≥29dB; when the fiber ratio is further preferred, its average shielding effectiveness at 8-12.4GHz is further increased to more than 40dB; and the electromagnetic shielding effectiveness in the technical scheme of the present invention comes from the combination of carbon fiber and metal-plated fiber, and there is no metal that is easy to fall off. The fibers are particles and coated with resin binder on the surface, so that they will not be oxidized and fall off in water or air environment, thereby maintaining good electromagnetic shielding performance for a long time; further, in the technical solution of the present invention, by matching carbon fiber, metal-plated glass fiber and glass fiber in an optimal proportion, it has high mechanical strength and will not be damaged by pulling, and its tensile strength is ≥9N / 15mm. By further optimizing the fiber ratio and parameter design, its tensile strength can be as high as 16.5N / 15mm; due to its better electromagnetic shielding performance retention and high mechanical strength, it provides a guarantee for its long life; further, in the technical solution of the present invention, by coating the resin binder on the fiber surface, the shielding paper has good hydrophobicity, thereby further ensuring the long life of the shielding paper; and the electromagnetic shielding paper of the technical solution of the present invention can be used in harsh use environments and still ensure the stability of its performance.

[0030] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the super hydrophobic electromagnetic shielding of the present invention;

[0032] Figure 2 Cross-sectional view of superhydrophobic electromagnetic shielding paper in Example 1 of the present invention;

[0033] Figure 3 This is the Al element distribution diagram of the super hydrophobic electromagnetic shielding paper in Example 1 of the present invention;

[0034] Figure 4 This is the C element distribution diagram of the superhydrophobic electromagnetic shielding paper in Example 1 of the present invention;

[0035] Figure 5 This is a diagram of the electromagnetic shielding effectiveness of the superhydrophobic electromagnetic shielding paper in Example 1 of the present invention;

[0036] Figure 6 This is a microscope photograph of the hydrophobic angle of the super-hydrophobic electromagnetic shielding paper in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a super-hydrophobic electromagnetic shielding paper and its preparation method and its specific implementation, structure, characteristics and effects of the application proposed by the present invention in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0038] The present invention provides a super hydrophobic electromagnetic shielding paper, as shown in the attached Figure 1 As shown, it includes:

[0039] Metallized glass fiber layer 1;

[0040] A glass fiber layer 2, disposed adjacent to the metallized glass fiber layer;

[0041] A carbon fiber layer 3 is arranged adjacent to the glass fiber layer; the glass fibers on one side surface of the glass fiber layer are interspersed into the carbon fiber layer and entangled with the carbon fibers, and the glass fibers on the other side surface are interspersed into the metal-plated glass fiber layer and entangled with the metal-plated glass fibers; along the thickness direction of the super-hydrophobic electromagnetic shielding paper, the metal-plated glass fiber layer, the glass fiber layer and the carbon fiber layer are a density gradient structure; the metal-plated glass fiber layer, the glass fiber layer and the carbon fiber layer are bonded by a resin adhesive.

[0042] In the above technical scheme, although it is described as a three-layer structure according to the different fiber materials, in fact, the glass fiber not only exists as an intermediate layer, a part of the glass fiber extends downward into the metal-plated glass fiber layer to form a winding structure with the metal-plated glass fiber layer, forming a transition layer from the metal-plated glass fiber layer to the glass fiber layer; a part of the glass fiber extends upward into the carbon fiber layer to form a winding structure with the carbon fiber layer, forming a transition layer from the carbon fiber layer to the glass fiber layer; as recorded above, the super-hydrophobic electromagnetic shielding paper of the present invention actually includes a metal-plated glass fiber layer / a transition layer wound by metal-plated glass fiber and glass fiber / a glass fiber layer / a transition layer wound by carbon fiber and glass fiber / a carbon fiber layer from bottom to top. Since the density of carbon fiber is relatively small and the density of metal-plated glass fiber is relatively large, it is difficult to combine the two together; the present invention cleverly uses glass fiber with a medium density as a medium, and effectively combines the carbon fiber that is difficult to combine with the metal-plated glass fiber organically through the technical scheme of the present invention to form an overall structure with good bonding strength; the super-hydrophobic electromagnetic shielding paper of the present invention has a density gradient decreasing from the metal-plated glass fiber layer to the carbon fiber layer, that is, the super-hydrophobic electromagnetic shielding paper of the present invention has a density gradient structure. The layered material with a gradient density is beneficial to enhancing the process of electromagnetic wave absorption and reflection, thereby enhancing the shielding effectiveness of the shielding paper.

[0043] Furthermore, in order to enable the above-mentioned layered material with a gradual density gradient to maintain its structure stably for a long time, the present invention bonds the fiber layers together through a resin adhesive, which can stabilize its structure on the one hand, and on the other hand, the resin adhesive can also form a coating structure for the fibers, thereby improving the hydrophobicity of the shielding paper.

[0044] In the above technical scheme, both carbon fiber and metal-plated glass fiber have good electromagnetic shielding effect; carbon fiber has a thinner diameter, which is beneficial to the strength of shielding paper, but it is expensive; while metal-plated glass fiber has a thicker diameter and low strength, but its cost is also low; the present invention organically combines carbon fiber and metal-plated glass fiber into a whole through the above technical scheme, which not only ensures the mechanical strength of shielding paper, but also ensures its electromagnetic shielding effectiveness, and can better control its cost. In some specific embodiments of the present invention, the tensile strength of the super-hydrophobic electromagnetic shielding paper is ≥9N / 15mm, and the average shielding effectiveness of 8-12.4GHz is ≥25dB.

[0045] The present invention also provides a method for preparing super-hydrophobic electromagnetic shielding paper, which comprises the following steps:

[0046] The first step is to prepare the fiber slurry. Specifically: disperse the carbon fiber, metal-plated glass fiber and glass fiber in water, stir evenly to obtain fiber slurry; in order to make the three fibers better matched to achieve better comprehensive performance, the present invention preferably has a mass ratio of 0.1 to 0.4: 0.1 to 0.4: 1 for the carbon fiber, metal-plated glass fiber and glass fiber. Since the forming of the shielding paper may be affected when the fiber is too thick, in order to ensure the smooth film formation of the shielding paper prepared by the present invention, the present invention preferably has a diameter of all kinds of fibers ≤ 15 μm. The stirring process parameters can be selected according to the conventional ones in the field, and the present invention does not make specific restrictions thereon. The proportion of water added during slurry preparation is not specifically limited, as long as the fiber dispersion process can proceed smoothly and the fibers can be fully dispersed and entangled.

[0047] Furthermore, in order to ensure that the shielding paper has high shielding strength and good mechanical properties, the present invention further preferably has a fiber diameter of the first glass fiber ≤0.5 μm, a fiber diameter of the second glass fiber ≤1.5 μm; and a diameter of the metal-plated glass fiber ≤5 μm.

[0048] The second step is to naturally settle the fiber slurry, press and dry it to obtain the first shielding paper with a gradient density distribution.

[0049] In the above steps, after the fiber slurry is prepared, it is first allowed to stand and then allowed to settle naturally. Natural sedimentation can be carried out by conventional operations in the field; in a specific embodiment of the present invention, the drain valve of the fiber slurry container is opened, and the slurry is naturally settled on the forming wire of the paper machine by suction filtration to form a gradient structure, and the present invention does not make specific limitations on this. Pressing and drying can also be carried out by conventional operations in the field, as long as the moisture content can be reduced to a set level, and the present invention does not make specific limitations on this. For example, drying can be carried out at 80°C to 160°C according to the fiber properties.

[0050] Since the diameter of carbon fiber is extremely fine and the specific gravity is very light, while the specific gravity of metal-plated glass fiber is relatively large, it is difficult to organically integrate the two by direct combination; in order to enable the two to form a complete integral material, the present invention preferably uses glass fiber to link the two; the specific gravity of glass fiber is between that of carbon fiber and metal-plated glass fiber; through natural sedimentation, the glass fiber can be mainly between carbon fiber and metal-plated glass fiber; in order to strengthen the connection between the three, one side of the glass fiber extends into the interior of the carbon fiber to form a winding connection with the carbon fiber; the other side of the glass fiber extends into the interior of the metal-plated glass fiber to form a winding connection with the metal-plated glass fiber; thereby, the carbon fiber and the metal-plated glass fiber are linked as a whole through the glass fiber.

[0051] In order to enhance the fusion effect of carbon fiber and glass fiber, the present invention preferably follows the following steps when preparing the fiber slurry:

[0052] The carbon fiber and the first glass fiber are dispersed in water and stirred evenly to obtain a pre-entangled fiber slurry; in this step, the first glass fiber is not limited to its material and specification, but to its addition timing, indicating that it is first mixed with the carbon fiber alone, and the two are contacted in advance to form a pre-entangled link structure. In order to better control the proportion of the pre-entangled structure between the carbon fiber and the glass fiber, the present invention preferably has a mass ratio of the carbon fiber to the first glass fiber of 0.2 to 0.9:1.

[0053] Then, the metal-plated glass fiber, the second glass fiber and the pre-entangled fiber slurry are dispersed in water and stirred evenly to obtain a fiber slurry; in this step, the second glass fiber is not limited to its material and specification, but to its addition time, indicating that it is mixed with the pre-entangled carbon fiber and glass fiber mixture and the metal-plated glass fiber at a later stage, so that the three fibers are in contact, so that the three fibers are entangled for the second time, and a fiber slurry with a specific entanglement structure is formed, thereby ensuring that it will not be delaminated in the subsequent process steps, and providing a guarantee for the strength of the electromagnetic shielding paper of the present invention. In order to ensure that the second glass fiber can form an intermediate dielectric layer in the subsequent process, and can extend into the carbon fiber layer and the metal-plated glass fiber layer on both sides, the present invention preferably has a mass ratio of the metal-plated glass fiber to the second glass fiber of 0.2 to 0.9:1; that is, by adding a large amount of glass fiber to the fiber slurry system, the carbon fiber and the metal-plated glass fiber are organically integrated into a better strength overall structure.

[0054] Through a large number of experimental analyses, it was found that when the mass ratio of carbon fiber and metal-plated glass fiber is controlled at 0.6-1.7:1, the two fibers can achieve a better balance. A sufficient amount of carbon fiber can give the shielding paper a higher shielding strength, and a sufficient amount of metal-plated glass fiber can reduce the cost of the shielding paper. Moreover, under this ratio, the two can also form a better bonded whole with a density gradient structure through entanglement with glass fiber and bonding through resin adhesive, so that the shielding paper of the present invention has high shielding strength, good mechanical properties, and cost savings.

[0055] Through a large number of experimental analyses, it was also found that when the mass ratio of the sum of carbon fiber and metal-plated glass fiber to glass fiber is controlled at 0.35-0.70:1, the three fibers can achieve a better balance. A sufficient amount of glass fiber can not only enable the shielding paper to maintain the high temperature resistance of conventional shielding paper, but also ensure a certain thickness of the glass fiber intermediate layer to form a better density gradient structure. There can also be enough glass fiber extending into the carbon fiber layer and the metal-plated glass fiber layer on both sides to stably link the three and avoid stratification of the carbon fiber layer and the metal-plated glass fiber layer, thereby providing sufficient mechanical properties for the shielding paper.

[0056] Furthermore, the present invention controls the ratio of the sum of the masses of the carbon fiber and the first glass fiber (calculated as A) to the sum of the masses of the metal-plated glass fiber and the second glass fiber (calculated as B) (i.e., A to B) within an appropriate range, preferably in a ratio of 0.2 to 1:1, so that the thickness of the carbon fiber layer and the metal-plated glass fiber layer in the layered structure of the electromagnetic shielding paper can be controlled to be appropriate, thereby avoiding the carbon fiber layer being too thin relative to the metal-plated glass fiber layer, or avoiding the metal-plated glass fiber layer being too thin relative to the carbon fiber layer, thereby ensuring that the overall structure formed in the subsequent sedimentation process has better bonding and higher strength.

[0057] Finally, a resin adhesive is applied to the surface of the first shielding paper and dried to obtain a super-hydrophobic electromagnetic shielding paper. In this step, the steps of applying a resin adhesive to the surface of the first shielding paper are as follows: the first shielding paper is soaked in a deionized water solution of acrylic resin for ≤1 min to obtain a second shielding paper; wherein, the acrylic resin can be a modified acrylic resin, which is coated on the fiber surface to form a protection for the fiber structure, and can also bond the fibers together, so that the shielding paper can ensure a stable density gradient structure. The modified acrylic resin can be a conventional adhesive for shielding paper in the field, and the present invention does not specifically limit this. Then, an ethanol solution of fluoroalkyl silane is sprayed on the second shielding paper to form a highly hydrophobic structure on the surface of the acrylic resin. The present invention arranges acrylic resin and fluoroalkyl silane on the fiber surface in sequence, and the two together form a super-hydrophobic structure on the surface of the paper, so that the shielding paper has super-hydrophobic properties. The super hydrophobic electromagnetic shielding paper prepared by the preparation method of the present invention has a tensile strength of ≥9N / 15mm, an average shielding effectiveness of 8-12.4GHz ≥25dB, a hydrophobic angle ≥147°, and has better comprehensive performance.

[0058] In order to further improve the mechanical strength of the super-hydrophobic electromagnetic shielding paper, the super-hydrophobic electromagnetic shielding paper of the present invention further includes a non-woven fabric layer; the non-woven fabric layer is arranged on both sides of the super-hydrophobic electromagnetic shielding paper, and is bonded to the metal-plated glass fiber layer and the carbon fiber layer respectively by a resin adhesive. By arranging the non-woven fabric layer on both sides of the shielding paper, the mechanical strength of the shielding paper can be greatly improved. As shown in Example 9, its tensile strength is increased from 15N / 15mm in Example 1 to 32.5N / 15mm in Example 9, and the improvement rate is as high as 116.7%.

[0059] The super-hydrophobic electromagnetic shielding paper is preferably prepared according to the above-mentioned preparation method of the present invention.

[0060] The present invention also proposes an application of the aforementioned super-hydrophobic electromagnetic shielding paper in the field of electromagnetic shielding materials. The applicant has found that although the electromagnetic shielding effect is better when the shielding paper is generally applied, one side of the carbon fiber layer can be used as the surface to allow electromagnetic waves to be incident from this side; however, when the shielding paper is applied, it is preferred to use one side of the metal-plated glass fiber layer as the surface to allow electromagnetic waves to be incident from this side, and the electromagnetic shielding effect will be further enhanced, as shown in the test results of Example 5.

[0061] The present invention will be further described below in conjunction with specific embodiments, but this should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by technicians in this field based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0062] Example 1

[0063] In this embodiment, shielding paper is prepared by a natural sedimentation method, and the specific steps are as follows:

[0064] 1) Put 1 g of glass fiber with a diameter of 0.1 μm and 0.5 g of carbon fiber into 2 L of deionized water and stir them in a blender at a speed of 3000 rpm for 5 min to entangle the carbon fiber and the glass fiber;

[0065] 2) 0.5 g of 5 μm diameter aluminum-coated glass fiber, 1.5 g of the mixed fiber in step 1), and 1 g of 1.5 μm diameter glass fiber were mixed with 4 L of deionized water, and a mixed slurry was prepared under the same stirring conditions as step 1);

[0066] 3) Pour the mixed slurry in step 2) into the slurry tank of the sheet making machine and let it stand for 2 minutes;

[0067] 4) Open the water valve to allow the slurry in step 3) to naturally fall onto the forming wire to form a paper film;

[0068] 5) The paper film in step 4) is squeezed at 2 MPa and dried at 100° C. for 5 min;

[0069] 6) Soaking the paper obtained in step 5) in a mixed solution of deionized water and acrylic resin in a mass ratio of 60:1 for 30 seconds, and taking it out;

[0070] 7) Fluoroalkyl silane (FAS-17) was dissolved in anhydrous ethanol at a mass ratio of 1:60, and the mixed solution was sprayed on the surface of the composite paper obtained in step 6), and then dried at 120° C. for 20 minutes to obtain a hydrophobic shielding paper.

[0071] The cross-sectional microscopic morphology of the shielding paper prepared in this embodiment is shown in the attached figure. Figure 2 As shown; attached Figure 3 The Al element distribution diagram of the cross section containing the metal-plated fiber layer is shown in FIG. Figure 4 Shown is a C element distribution diagram of a cross section including a carbon fiber layer.

[0072] The shielding paper prepared in this embodiment was tested for performance by conventional testing methods in the art. Its tensile strength was 15N / 15mm, and its average shielding effectiveness at 8-12.4GHz was 34.8dB (electromagnetic waves were incident from the direction of the carbon fiber layer). The test results are shown in the attached figure. Figure 5 As shown; the hydrophobic angle is 153.2°, as Figure 6 shown.

[0073] Embodiments 2 to 11

[0074] The process steps are the same as those in Example 1, and the process parameters and differences are shown in Table 1. In Example 5, when testing the shielding performance, the electromagnetic wave was also incident from the direction of the metallized glass fiber layer for testing. In Example 9, 20 g / m2 of the shielding paper film was laid on both the upper and lower surfaces. 2 The nonwoven fabric layer was then pressed, and the performance test results are shown in Table 1.

[0075] Table 1

[0076]

[0077] Note: "Shielding effectiveness 1" in the table is the result of testing when electromagnetic waves are incident from the direction of the carbon fiber layer; "Shielding effectiveness 2" is the result of testing when electromagnetic waves are incident from the direction of the metallized glass fiber layer.

[0078] It can be seen from the test results of the embodiments and comparative examples that changing the diameter of the glass fiber will affect the degree of mixing of the glass fiber and the carbon fiber; as the diameter of the glass fiber increases, the tensile strength and hydrophobic angle of the prepared shielding paper gradually decrease, while the shielding effectiveness for electromagnetic shielding changes little, as shown in Examples 1 to 3.

[0079] It can also be seen from the test results of the embodiments and comparative examples that changing the content of carbon fiber can significantly affect the mechanical strength and shielding effectiveness of the shielding paper; with the increase of the carbon fiber content, the electromagnetic shielding effectiveness of the shielding paper is significantly improved, and the tensile strength of the shielding paper also gradually increases, and the rate of increase gradually slows down; while the effect on the hydrophobic angle is relatively small, as shown in Examples 1 and 4 to 5.

[0080] It can also be seen from the test results of the embodiments and comparative examples that changing the content of metal-coated glass aluminum fibers will affect the mixed stacking of the fibers; as the content of aluminum-coated glass fibers increases, the tensile strength of the shielding paper gradually decreases, and the electromagnetic shielding effectiveness gradually increases, while the effect on the hydrophobic angle is relatively small, as shown in Examples 2, 6, and 7.

[0081] It can also be seen from the test results of the embodiments and comparative examples that arranging non-woven fabrics on both sides of the shielding paper can greatly improve the tensile strength of the shielding paper, as shown in Embodiment 2 and Embodiment 9.

[0082] It can also be seen from the test results of the embodiments and comparative examples that when the shielding paper is used, when the electromagnetic wave is incident through the metal-plated glass fiber layer as the surface, it can achieve a better electromagnetic shielding effect than when the electromagnetic wave is incident through the carbon fiber layer as the surface, as shown in Example 5.

[0083] The technical features in the claims and / or the specification of the present invention may be combined, and the combination is not limited to the combination obtained by reference in the claims. The technical solution obtained by combining the technical features in the claims and / or the specification is also within the protection scope of the present invention.

[0084] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for preparing super-hydrophobic electromagnetic shielding paper, characterized in that: It includes the following steps: S11 disperses carbon fiber, metal-plated glass fiber and glass fiber in water, and stirs evenly to obtain fiber slurry; wherein the mass ratio of the carbon fiber, metal-plated glass fiber and glass fiber is 0.1-0.4:0.1-0.4:1; S12: naturally settling the fiber slurry, pressing and drying it to obtain a first shielding paper with a gradient density distribution; S13: applying a resin adhesive to the first shielding paper and drying it to obtain a super-hydrophobic electromagnetic shielding paper.

2. The preparation method according to claim 1, characterized in that: The preparation steps of the fiber slurry are as follows: S21 disperses the carbon fiber and the first glass fiber in water and stirs them evenly to obtain a pre-entangled fiber slurry; wherein the mass ratio of the carbon fiber to the first glass fiber is 0.2 to 0.9:1; S22 disperses the metal-plated glass fiber, the second glass fiber and the pre-entangled fiber slurry in water, stirs evenly, and obtains fiber slurry; wherein the mass ratio of the metal-plated glass fiber to the second glass fiber is 0.2 to 0.9:1; the ratio of the sum of the mass of the carbon fiber and the first glass fiber to the sum of the mass of the metal-plated glass fiber and the second glass fiber is 0.2 to 1:

1.

3. The preparation method according to claim 1 or 2, characterized in that: The mass ratio of the carbon fiber to the metal-plated glass fiber is 0.6-1.7:1; the mass ratio of the sum of the carbon fiber and the metal-plated glass fiber to the glass fiber is 0.35-0.70:

1.

4. The preparation method according to claim 2, characterized in that: The fiber diameter of the first glass fiber is ≤0.5 μm; the fiber diameter of the second glass fiber is ≤1.5 μm; and the diameter of the metal-plated glass fiber is ≤5 μm.

5. The preparation method according to claim 1, characterized in that: The steps of applying resin adhesive on the surface of the first shielding paper are as follows: S51: soaking the first shielding paper in a deionized water solution of acrylic resin for ≤1 min to obtain a second shielding paper; S52: spraying the ethanol solution of fluoroalkylsilane onto the second shielding paper.

6. A super hydrophobic electromagnetic shielding paper, characterized in that: It includes: Metallized fiberglass layer; a glass fiber layer disposed adjacent to the metallized glass fiber layer; A carbon fiber layer is arranged adjacent to the glass fiber layer; the glass fibers on one side surface of the glass fiber layer are interspersed into the carbon fiber layer and entangled with the carbon fibers, and the glass fibers on the other side surface are interspersed into the metal-plated glass fiber layer and entangled with the metal-plated glass fibers; along the thickness direction of the super-hydrophobic electromagnetic shielding paper, the metal-plated glass fiber layer, the glass fiber layer and the carbon fiber layer are a density gradient structure; the metal-plated glass fiber layer, the glass fiber layer and the carbon fiber layer are bonded by a resin adhesive.

7. The super-hydrophobic electromagnetic shielding paper according to claim 6, characterized in that: Its tensile strength is ≥9N / 15mm, the average shielding effectiveness from 8 to 12.4GHz is ≥25dB, and the hydrophobic angle is ≥147°.

8. The super-hydrophobic electromagnetic shielding paper according to claim 6, characterized in that: It also includes: The non-woven fabric layer is arranged on both sides of the super-hydrophobic electromagnetic shielding paper and is respectively bonded to the metal-plated glass fiber layer and the carbon fiber layer through the resin adhesive.

9. The super-hydrophobic electromagnetic shielding paper according to any one of claims 6 to 8, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 5.

10. Use of the super-hydrophobic electromagnetic shielding paper according to any one of claims 6 to 9 in the field of electromagnetic shielding materials.

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