Ultra-wideband, lightweight, microwave-absorbing silicone gasket and preparation method thereof

Abstract

The invention discloses a kind of ultra-wideband thin and light absorbing organosilicon gasket, by mass percentage, is formed by the following raw materials: 20wt% 40wt% high viscosity vinyl silicone oil, 1wt% 5wt% low viscosity vinyl silicone oil, 2wt% 20wt% hydrogenated silicone oil, 0.2wt% platinum catalyst, 5wt% 15wt% soft magnetic absorbing powder, 15wt% 25wt% dielectric type absorbing powder, 25wt% 40wt% carbonyl iron absorbing powder.By setting the raw material preparation of above-mentioned proportion range, absorbing organosilicon gasket is prepared, principle is to adopt high and low viscosity silicone oil compounding mode, and then play viscosity reduction and the mode of absorbing powder surface wrapping, while being conducive to absorbing powder dispersion, organosilicon gasket is made to have high ductility and good toughness, and, by the ratio of above-mentioned 3 kinds of absorbing powder, reasonable collocation, synergistic effect, widen the electromagnetic wave absorption band of absorbing organosilicon gasket, can cover microwave band under different thicknesses. The invention also discloses a preparation method of the wave-absorbing organic silicon gasket.

Description

Technical Field

[0001] The present invention relates to the technical field of wave-absorbing organic silicon gaskets, and in particular to an ultra-wideband, light and thin wave-absorbing organic silicon gasket and a preparation method thereof. Background Art

[0002] With the rapid development of new energy vehicles and the communications industry, electronic equipment is becoming increasingly widely used. Electromagnetic wave absorbing silicone materials are gaining attention as functional materials that improve the electromagnetic environment and suppress the interaction between electronic components. The increasing integration of electronic components is placing higher demands on the performance of electromagnetic wave absorbing silicone gaskets, such as reducing their thickness to achieve greater space utilization. For example, Chinese patent document CN117801533A discloses a high-thermal-conductivity, high-insulation, ultra-thin, flexible, and absorbing composite material. The composite material comprises the following raw materials, in parts by weight: 45-70 parts of modified absorbing powder, 40 parts of vinyl silicone oil, 5-10 parts of hydrogenated silicone oil, 50 parts of aluminum oxide powder, and 0.4 parts of a catalyst. The modified absorbing powder, vinyl silicone oil, hydrogenated silicone oil, aluminum oxide powder, and catalyst are mixed and stirred, and subjected to vacuum defoaming treatment to obtain a thermally conductive and absorbing mixed slurry. The thermally conductive and absorbing mixed slurry is then evenly coated on a carrier film by cast coating, and then dried and cured in a multi-step temperature gradient at 40-60°C, 65-135°C, 110-140°C, 60-90°C, and 25-50°C to obtain a 0.06-2 mm high-thermal-conductivity, high-insulation, ultra-thin, flexible, and absorbing composite gasket. For another example, Chinese patent document CN113249031B discloses a high thermal conductivity silicone absorber, which comprises the following components in parts by mass: 10-85 parts of resin, 41-120 parts of magnetic powder, 5-55 parts of thermal conductive filler, and 1.4-41 parts of auxiliary agents, wherein the resin is selected from one or more of polyalkyl silicone resin, polyaryl silicone resin and polyalkylaryl silicone resin; the molecular weight of the resin is 5000-120000; the thermal conductive filler is selected from one or more of aluminum oxide, aluminum oxide monohydrate, aluminum oxide dihydrate, ferric oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, insulating carbon black, and graphene; the magnetic powder is selected from one or more of diamagnetic, paramagnetic, ferromagnetic, antiferromagnetic or ferrimagnetic powders; the 1.4-41 parts of auxiliary agents include: 0.5-10 parts of a cross-linking agent, 0.1-2 parts of a coupling agent, 0.1-3 parts of an antioxidant, 0 0.1-3 parts of defoaming agent, 0.1-3 parts of wetting agent, 0.5-20 parts of pH regulator; obtain the following components by mass: 10-85 parts of resin, 41-120 parts of magnetic powder, 5-55 parts of thermal conductive filler, 1.4-41 parts of auxiliary agent; mix evenly at 2-5°C under vacuum conditions, add catalyst and solvent, and mix evenly again to obtain a slurry; S20: use the slurry to apply a coating with a coating thickness of 0.15-3mm, and dry to obtain the absorbing sheet. It can be seen that thin absorbing gaskets and other structures have appeared in the prior art, specifically absorbing gaskets less than or equal to 3mm. However, the effective absorption bandwidth of the thin absorbing gaskets in the above-mentioned technology is very narrow, which is difficult to meet the demand for thin absorbing gaskets in modern electronic equipment. Summary of the Invention

[0003] To solve the above technical problems, the present invention provides an ultra-wideband, lightweight, and absorbing silicone gasket, which is formed from the following raw materials, in terms of mass percentage: 20wt%-40wt% of high-viscosity vinyl silicone oil, 1wt%-5wt% of low-viscosity vinyl silicone oil, 2wt%-20wt% of hydrogen-containing silicone oil, 0.2wt% of platinum catalyst, 5wt%-15wt% of soft magnetic absorbing powder, 15wt%-25wt% of dielectric absorbing powder, and 25wt%-40wt% of carbonyl iron absorbing powder. The microwave-absorbing silicone gasket is prepared by setting the raw materials in the above-mentioned ratio range. The principle is to use a compound method of high- and low-viscosity silicone oils to reduce viscosity and coat the surface of the microwave-absorbing powder. This not only facilitates the dispersion of the microwave-absorbing powder, but also makes the silicone gasket have high ductility and good toughness. In addition, through the reasonable ratio and synergistic effect of the above-mentioned three microwave-absorbing powders, the electromagnetic wave absorption frequency band of the microwave-absorbing silicone gasket is broadened, and the microwave frequency band can be covered at different thicknesses, so that the microwave-absorbing silicone gasket can meet the needs of different frequency bands, overcoming the defect of the existing microwave-absorbing gaskets having a very narrow effective absorption bandwidth. In particular, when the thickness is 2 mm or less, especially when the thickness is 0.3-2 mm, the microwave-absorbing silicone gasket prepared by using the above-mentioned raw materials has an effective absorption band (≤-10 dB, electromagnetic wave absorption rate greater than 90%) that can cover at least 8-36.8 GHz, greatly improving the effective absorption band of the microwave-absorbing silicone gasket at a thin thickness, expanding the scope of application, and surpassing the 9.8-32.6 GHz coverage range of the microwave-absorbing gaskets in the prior art.

[0004] In one embodiment, the following raw materials are used, in terms of mass percentage: 33.7 wt% of high-viscosity vinyl silicone oil, 3 wt% of low-viscosity vinyl silicone oil, 3.1 wt% of hydrogenated silicone oil, 0.2 wt% of platinum catalyst, 10 wt% of soft magnetic absorbing powder, 20 wt% of dielectric absorbing powder, and 30 wt% of carbonyl iron absorbing powder. By further limiting the raw material range of the absorbing silicone gasket, the prepared absorbing silicone gasket has an effective absorption band (≤-10dB, electromagnetic wave absorption rate greater than 90%) of 5.5-40GHz (C, X, Ku, K, Ka bands) when the thickness is 2mm or less, especially when the thickness is 0.3-2mm, achieving the maximum coverage range; moreover, when the thickness of the absorbing silicone gasket is 0.4mm, the reflection loss is the lowest and the absorbing performance is the strongest, reaching -27dB. That is, the absorbing silicone gasket with the above ratio can still achieve excellent absorbing performance when it is very thin, which is far superior to the absorbing performance of the absorbing gasket in the prior art that can only be achieved at a thickness of 2mm.

[0005] In one embodiment, the viscosity of the high-viscosity vinyl silicone oil is 1000-10000 cs, the viscosity of the low-viscosity vinyl silicone oil is 50-200 cs, and the viscosity of the hydrogenated silicone oil is 20-200 cs.

[0006] In one embodiment, the high-viscosity vinyl silicone oil is at least one of terminal vinyl silicone oil, side vinyl silicone oil and terminal side vinyl silicone oil; the low-viscosity vinyl silicone oil is at least one of terminal vinyl silicone oil, side vinyl silicone oil and terminal side vinyl silicone oil; the hydrogen-containing silicone oil is at least one of terminal hydrogen-containing silicone oil and side hydrogen-containing silicone oil; and the platinum catalyst is a Karstedt catalyst.

[0007] In one embodiment, the sum of the weight percentages of the soft magnetic absorbing powder, the dielectric absorbing powder, and the carbonyl iron absorbing powder is 50 wt% to 70 wt%. The best effect is achieved by controlling the total weight of the three absorbing powders to be 50-70 wt%.

[0008] In one embodiment, the soft magnetic absorbing powder is at least one of iron-based alloy powders such as sendust, iron-nickel, and iron-cobalt alloy and / or ferrite; the dielectric absorbing powder is at least one of barium titanate, silicon carbide, silicon nitride, boron nitride, and iron nitride.

[0009] In one embodiment, the particle size of the soft magnetic absorbing powder is 50-200 μm; the particle size of the dielectric absorbing powder is 3-50 μm; and the particle size of the carbonyl iron absorbing powder is 3-50 μm.

[0010] In one embodiment, the soft magnetic absorbing powder, the dielectric absorbing powder and the carbonyl iron absorbing powder are in the shape of one or more of sphere, rhombus, dendrite, flake and needle.

[0011] The invention also discloses a method for preparing an ultra-wideband, light and thin wave-absorbing organic silicon gasket, which comprises the following steps.

[0012] (1) Stirring: The high-viscosity vinyl silicone oil, the low-viscosity vinyl silicone oil, the hydrogenated silicone oil and the platinum catalyst are uniformly stirred under vacuum; then the soft magnetic absorbing powder, the dielectric absorbing powder and the carbonyl iron absorbing powder are added, first stirred until there is no powder, and then vacuum stirred to obtain a mixed slurry of silicone oil and absorbing powder.

[0013] (2) Calendering: Place the mixed slurry on release paper, cover the upper layer with release film, and use a calendering machine to calender; then, vulcanize it in a high-temperature drying oven to form a semi-finished absorbing silicone gasket.

[0014] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket.

[0015] Furthermore, in step (1), the vacuum stirring time is 1-3 minutes; in step (2), the thickness of the release paper is 0.2-0.5 mm, the thickness of the centrifugal membrane is 20 μm-100 μm, the length of the high-temperature drying tunnel is 8-12 m, the conveying speed is 0.5-1 m / min, and the temperature of the high-temperature drying tunnel is 80°C-120°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following is a brief introduction to the drawings required for use in the specific embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 3 is a reflection loss diagram of the absorbing silicone gasket of Example 1 of the present invention.

[0018] Figure 2 3 is a reflection loss diagram of the absorbing silicone gasket of Example 2 of the present invention.

[0019] Figure 3 3 is a reflection loss diagram of the absorbing silicone gasket of Example 3 of the present invention.

[0020] Figure 4 3 is a reflection loss diagram of the absorbing silicone gasket of Example 4 of the present invention.

[0021] Figure 5 3 is a reflection loss diagram of the absorbing silicone gasket of Example 5 of the present invention.

[0022] Figure 6 3 is a reflection loss diagram of the absorbing silicone gasket of Example 6 of the present invention.

[0023] Figure 7 3 is a reflection loss diagram of the absorbing silicone gasket of Example 7 of the present invention.

[0024] Figure 8 3 is a reflection loss diagram of the absorbing silicone gasket of Example 8 of the present invention.

[0025] Figure 9 3 is a reflection loss diagram of the absorbing pad of Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the present invention in conjunction with the accompanying drawings. It is obvious that the embodiments described are only some of the embodiments of the present invention, not all of them. The embodiments of the present invention and other embodiments obtained by ordinary technicians in this field without making creative efforts are all within the scope of protection of the present invention.

[0027] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0028] In the following embodiments, the manufacturer of high-viscosity vinyl silicone oil, low-viscosity vinyl silicone oil and hydrogen-containing silicone oil is Ningbo Runhe High-tech Materials Technology Co., Ltd.; the platinum catalyst is Karstedt catalyst, manufactured by Wacker (China) Technology Co., Ltd.; the manufacturer of carbonyl iron (wherein C < 0.75, O < 0.50, N < 0.75) is Jiangsu Tianyi Ultrafine Metal Powder Co., Ltd.; the manufacturer of sendust is Taicang Xianghui Electronic Materials Co., Ltd.; the manufacturer of barium titanate is Tianjin Jersey Mineral Processing Co., Ltd.; and the manufacturer of silicon carbide is Shandong Jinmeng New Materials Co., Ltd. Example 1

[0029] (1) Stirring: 33.7 wt% of vinyl-terminated silicone oil with a viscosity of 5000 cs, 3 wt% of vinyl-terminated silicone oil with a viscosity of 100 cs, 3.1 wt% of hydrogen-terminated silicone oil with a viscosity of 100 cs and 0.2% of platinum catalyst were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 2 min, and the vacuum degree was -0.08 MPa; then 10 wt% of flaky iron silicon aluminum with a particle size of 100 μm, 20 wt% of barium titanate with a particle size of 10 μm and 30 wt% of hydroxy iron with a particle size of 10 μm were added, first stirred until there was no powder, and then vacuum stirred evenly, wherein the stirring speed was 800 r / min, the stirring time was 3 min, and the vacuum degree was -0.08 mMPa, to obtain a mixed slurry of silicone oil and absorbing powder.

[0030] (2) Calendering: Place the mixed slurry on a 0.2 mm thick release paper, cover the upper layer with a 20 μm thick release film, and use a calendering machine for calendering. Then, vulcanize the semi-finished absorbing silicone gasket through an 8 m long high-temperature drying tunnel, wherein the conveying speed is 0.5 m / min and the temperature is 100 ° C. The thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0031] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket. Example 2

[0032] (1) Stirring: 19.8 wt% of end-vinyl silicone oil with a viscosity of 1000 cs, 1 wt% of side vinyl silicone oil with a viscosity of 50 cs, 19 wt% of side hydrogen silicone oil with a viscosity of 20 cs and 0.2% of platinum catalyst were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 800 r / min, the stirring time was 2 min, and the vacuum degree was -0.09 MPa; then 10 wt% of iron-nickel alloy with a particle size of 100 μm (iron-nickel weight ratio of 1:1, produced by Shijia Weier Technology Co., Ltd.), 20 wt% of silicon carbide with a particle size of 10 μm and 30 wt% of hydroxy iron with a particle size of 10 μm were added, first stirred until there was no powder, and then vacuum stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 4 min, and the vacuum degree was -0.08 mMPa, to obtain a mixed slurry of silicone oil and absorbing powder.

[0033] (2) Calendering: Place the mixed slurry on a 0.5 mm thick release paper, cover the upper layer with a 50 μm thick release film, and use a calendering machine for calendering. Then, vulcanize the semi-finished absorbing silicone gasket through a 12 m long high-temperature drying tunnel, wherein the conveying speed is 1 m / min and the temperature is 120 ° C. The thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0034] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket. Example 3

[0035] (1) Stirring: 34.8 wt% of end-vinyl silicone oil with a viscosity of 10000 cs, 3 wt% of end-side vinyl silicone oil with a viscosity of 200 cs, 2 wt% of end-hydrogen silicone oil with a viscosity of 200 cs and 0.2% of platinum catalyst were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 3 min, and the vacuum degree was -0.09 MPa; then 10 wt% of iron-cobalt alloy with a particle size of 100 μm (iron-cobalt weight ratio of 1:1, produced by Hebei Junchen Metal Products Co., Ltd.), 20 wt% of silicon nitride with a particle size of 10 μm (produced by Shanghai Yaotian New Materials Technology Co., Ltd.) and 30 wt% of hydroxy iron with a particle size of 10 μm were added, first stirred until there was no powder, and then vacuum stirred evenly, wherein the stirring speed was 800 r / min, the stirring time was 2 min, and the vacuum degree was -0.09 mMPa, to obtain a mixed slurry of silicone oil and absorbing powder.

[0036] (2) Calendering: Place the mixed slurry on a 0.2 mm thick release paper, cover the upper layer with a 100 μm thick release film, and use a calendering machine for calendering. Then, vulcanize the semi-finished absorbing silicone gasket through an 8 m long high-temperature drying tunnel, wherein the conveying speed is 0.5 m / min and the temperature is 120 ° C. The thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0037] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket. Example 4

[0038] (1) Stirring: 39.8 wt% of side vinyl silicone oil with a viscosity of 5000 cs, 5 wt% of end vinyl silicone oil with a viscosity of 100 cs and 5 wt% of end hydrogen silicone oil with a viscosity of 100 cs were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 800 r / min, the stirring time was 1 min, and the vacuum degree was -0.08 MPa; then 5 wt% of ferroferric oxide with a particle size of 100 μm (Jiangxi Yuean New Materials Co., Ltd.), 20 wt% of boron nitride with a particle size of 10 μm (produced by Yingkou Liaobin Fine Chemical Co., Ltd.) and 25 wt% of hydroxy iron with a particle size of 10 μm were added, first stirred until there was no powder, and then vacuum stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 3 min, and the vacuum degree was -0.08 mMPa, to obtain a mixed slurry of silicone oil and absorbing powder.

[0039] (2) Calendering: The mixed slurry is placed on a 0.5 mm thick release paper, and the upper layer is covered with a 20 μm thick release film, and calendered using a calendering machine; then, the mixed slurry is vulcanized in a 12 m long high-temperature drying tunnel to form a semi-finished absorbing silicone gasket, wherein the conveying speed is 1 m / min and the temperature is 80 ° C; wherein the thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0040] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket. Example 5

[0041] (1) Stirring: 24.8 wt% of end-side vinyl silicone oil with a viscosity of 5000 cs, 3 wt% of end-side vinyl silicone oil with a viscosity of 100 cs, 1 wt% of end-hydrogen silicone oil with a viscosity of 100 cs, 1 wt% of side vinyl silicone oil with a viscosity of 100 cs and 0.2% of platinum catalyst were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 2 min, and the vacuum degree was -0.09 MPa; then 10 wt% of sendust with a particle size of 100 μm, 5 wt% of iron-nickel alloy with a particle size of 100 μm (iron-nickel weight ratio of 1:1, produced by Hebei Junchen Metal Products Co., Ltd.), 15 wt% of barium titanate with a particle size of 10 μm and 40 wt% of hydroxy iron with a particle size of 10 μm were added, first stirred until there was no powder, and then vacuum stirred evenly, wherein the stirring speed was 800 r / min. r / min, the stirring time was 1 min, the vacuum degree was -0.09 mMPa, and a mixed slurry of silicone oil and absorbing powder was obtained.

[0042] (2) Calendering: Place the mixed slurry on a 0.2 mm thick release paper, cover the upper layer with a 50 μm thick release film, and use a calendering machine for calendering. Then, vulcanize the semi-finished absorbing silicone gasket through an 8 m long high-temperature drying tunnel, wherein the conveying speed is 0.5 m / min and the temperature is 100 ° C. The thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0043] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket. Example 6

[0044] (1) Stirring: 10 wt% of side vinyl silicone oil with a viscosity of 5000 cs, 16.8 wt% of terminal vinyl silicone oil with a viscosity of 5000 cs, 3 wt% of terminal vinyl silicone oil with a viscosity of 100 cs, 10 wt% of terminal hydrogen silicone oil with a viscosity of 100 cs and 0.2% of platinum catalyst were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 800 r / min, the stirring time was 1 min, and the vacuum degree was -0.08 MPa; then 10 wt% of iron silicon aluminum with a particle size of 100 μm, 15 wt% of barium titanate with a particle size of 30 μm, 5 wt% of silicon carbide with a particle size of 30 μm and 30 wt% of hydroxy iron with a particle size of 30 μm were added, first stirred until there was no powder, and then vacuum stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 3 min, and the vacuum degree was -0.09 mMPa, to obtain a mixed slurry of silicone oil and absorbing powder.

[0045] (2) Calendering: The mixed slurry is placed on a 0.5 mm thick release paper, and the upper layer is covered with a 100 μm thick release film, and calendered using a calendering machine; then, the mixed slurry is vulcanized in a 12 m long high-temperature drying tunnel to form a semi-finished absorbing silicone gasket, wherein the conveying speed is 1 m / min and the temperature is 120 ° C; wherein the thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0046] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket. Example 7

[0047] (1) Stirring: 21.8 wt% of 5000 cs vinyl-terminated silicone oil, 1 wt% of 100 cs vinyl-terminated silicone oil, 2 wt% of 100 cs vinyl-side silicone oil, 15 wt% of 100 cs hydrogen-terminated silicone oil and 0.2% of platinum catalyst were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 1 min, and the vacuum degree was -0.09 MPa; then 10 wt% of 200 μm flake iron silicon aluminum, 20 wt% of 50 μm barium titanate and 30 wt% of 50 μm hydroxy iron were added, stirred until there was no powder, and then stirred evenly in vacuum, wherein the stirring speed was 800 r / min, the stirring time was 2 min, and the vacuum degree was -0.09 mMPa, to obtain a mixed slurry of silicone oil and absorbing powder.

[0048] (2) Calendering: Place the mixed slurry on a 0.2 mm thick release paper, cover the upper layer with a 20 μm thick release film, and use a calendering machine for calendering. Then, vulcanize the semi-finished absorbing silicone gasket through an 8 m long high-temperature drying tunnel, wherein the conveying speed is 0.5 m / min and the temperature is 80 ° C. The thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0049] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket. Example 8

[0050] (1) Stirring: 28.7 wt% of vinyl-terminated silicone oil with a viscosity of 5000 cs, 3 wt% of vinyl-side silicone oil with a viscosity of 100 cs, 3.1 wt% of hydrogen-terminated silicone oil with a viscosity of 100 cs and 0.2% of platinum catalyst were placed in a vacuum homogenizer and stirred evenly, wherein the stirring speed was 800 r / min, the stirring time was 1 min, and the vacuum degree was -0.08 MPa; then 10 wt% of flaky iron silicon aluminum with a particle size of 50 μm, 25 wt% of barium titanate with a particle size of 3 μm and 30 wt% of hydroxy iron with a particle size of 3 μm were added, first stirred until there was no powder, and then vacuum stirred evenly, wherein the stirring speed was 600 r / min, the stirring time was 3 min, and the vacuum degree was -0.08 mMPa, to obtain a mixed slurry of silicone oil and absorbing powder.

[0051] (2) Calendering: Place the mixed slurry on a 0.5 mm thick release paper, cover the upper layer with a 50 μm thick release film, and use a calendering machine for calendering. Then, vulcanize the semi-finished absorbing silicone gasket through a 12 m long high-temperature drying tunnel, wherein the conveying speed is 0.5 m / min and the temperature is 100 ° C. The thickness of the semi-finished absorbing silicone gasket is 2 mm.

[0052] (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket.

[0053] Comparative Example 1

[0054] S10: Obtain the following components in parts by mass: 60 parts of resin (molecular weight 12000), 100 parts of carbonyl iron powder, 10 parts of graphene, 1 part of cross-linking agent, 0.8 parts of coupling agent, 1.2 parts of antioxidant, 0.3 parts of defoaming agent, 0.5 parts of wetting agent, and 5 parts of pH regulator; mix them evenly at 2°C under vacuum conditions; after stirring evenly, add a catalyst, add a solvent to adjust the viscosity, and control the viscosity at 1000 mPa·s, and stir evenly again to obtain the slurry; wherein, the resin is selected from polyalkyl silicone resin, polyaryl silicone resin and polyalkylaryl silicone resin; the cross-linking agent is glycidyl ether; the coupling agent is aminosilane coupling agent; the antioxidant is bleaching agent; the defoaming agent is a silicone defoaming agent; the wetting agent is a silicone wetting agent; the pH regulator is 2-amino-2-methyl-1-propanol; and the solvent is a benzene solvent.

[0055] S20: forming an absorbing gasket by subjecting the slurry to the calendering and cutting process of Example 1.

[0056] Test Case

[0057] The 2 mm thick absorbing silicone gaskets and the absorbing gasket obtained in Examples 1-8 and Comparative Example 1 were tested, and the specific test items were: effective absorption band coverage test and tensile test.

[0058] 1. Effective absorption band coverage experiment.

[0059] According to the National Standard of the People's Republic of China GB / T32596-2016 - General Specification for Electromagnetic Shielding Absorbers, the absorbing performance of the absorbers was tested using a Keysight Technologies (China) Ltd. E5080B network analyzer (100kHz-44GHz) and a transmission line. The details are as follows.

[0060] 1. Prepare test samples.

[0061] 1.1 Coaxial transmission line test The test sample is a concentric ring specimen.

[0062] The outer diameter is 6.95-7.00mm, the inner diameter is 3.05-3.10mm, and the concentricity deviation is less than 0.1mm.

[0063] 1.2 Waveguide transmission line samples are rectangular specimens.

[0064] The length is ±0.05mm of the basic width of the waveguide inner section, and the height is ±0.05mm of the basic height of the waveguide inner section.

[0065] 2. Use SOLT to calibrate the vector network analyzer.

[0066] 3. Place the absorbing sheet to be tested into the test fixture for testing. After placement, the sample surface should be perpendicular to the incident direction of the electromagnetic wave and should not be bent or tilted. The S parameters are measured.

[0067] 4. Process and plot the data obtained from the test. Figure 1-9 shown.

[0068] According to the above Figure 1-9 The results were analyzed by Figures 1-9 The results are shown in Table 1. Figure 1-9As can be seen from the results in Table 1, the absorbing silicone gaskets obtained in Examples 1-8, when the thickness is less than or equal to 2 mm, have an effective absorption band (≤-10 dB, electromagnetic wave absorptivity greater than 90%) covering at least 8-36.8 GHz, which is greater than the effective absorption band (≤-10 dB, electromagnetic wave absorptivity greater than 90%) of 9.8-32.6 GHz for absorbing gaskets less than or equal to 2 mm in the prior art. In other words, the absorbing silicone gaskets obtained in Examples 1-8, when the thickness is less than or equal to 2 mm, have an absorption bandwidth of at least 28.8 GHz, which is greater than the 22.8 GHz absorption bandwidth of absorbing gaskets less than or equal to 2 mm in the prior art. Specifically, the absorbing silicone gasket of Example 1, when the thickness is less than or equal to 2 mm, has an effective absorption band (≤-10 dB, electromagnetic wave absorptivity greater than 90%) covering 5.5-40.0 GHz, with an absorption bandwidth of 34.5 GHz, far superior to absorbing gaskets in the prior art. Moreover, the maximum absorption intensity of the absorbing silicone gaskets of Examples 1-8 when less than or equal to 2mm is greater than that of the prior art, especially the maximum absorption intensity of the absorbing gaskets of the prior art is 2mm, while the maximum absorption intensity of Examples 1-8 is less than 2mm, indicating that the absorption intensity of the absorbing silicone gasket of the present application when the thickness is thinner is better than the absorption intensity of the absorbing gasket of the same thickness in the prior art, and can even reach the absorption intensity of the thicker absorbing gaskets in the prior art. In particular, the absorbing silicone gasket of Example 1 has a maximum absorption intensity of -27dB when it is 0.4mm thick, which can achieve a greater absorption intensity with a thinner thickness, making it more suitable for applications with smaller spaces. In summary, the absorbing silicone gasket of the present application can achieve the absorption bandwidth and intensity of the thicker absorbing gaskets of the prior art in a light and thin thickness, or even better, and is suitable for small space applications.

[0069] Table 1

[0070] Effective absorption frequency band (GHz) Absorption bandwidth (GHz) (RL<-10dB) Absorption intensity (dB) Center frequency Example 1 5.5~40.0GHz 34.5 -27 (0.4mm) 36 Example 2 5.5~39.8GHz 34.3 -42.8 (0.8mm) 18.6 Example 3 7.4~38.7GHz 31.3 -25.8 (1mm) 13.4 Example 4 10.6~40.0GH 29.4 -25.5(1.1mm) 24 Example 5 6.2~40GHz 33.8 -31.1(0.7mm) 21.1 Example 6 5.6~36.8GHz 31.2 -30.8(1.2mm) 11.5 Example 7 8~36.8GHz 28.8 -39.6 (1.9mm) 10.2 Example 8 6.0 ~40.0GHz 34 -29.0 (1.0mm) 14 Comparative Example 1 9.8~32.6GHz 22.8 -24.8 (2mm) 14.8

[0071] 2. Tensile test.

[0072] According to the National Standard of the People's Republic of China GB / T528-2009 / ISO37:2005, Vulcanized rubber or thermoplastic rubber - Determination of tensile stress-strain properties, the tensile properties of the gasket are tested. The test method is as follows.

[0073] 1. Preparation of test samples.

[0074] Prepare no less than three dumbbell-shaped test samples of appropriate sizes according to national standards.

[0075] 2. Test samples.

[0076] Clamp the specimen symmetrically on the upper and lower clamps of the tensile testing machine so that the tensile force is evenly distributed over the cross section. Set the moving speed according to the standard, start the testing machine, and monitor the changes in specimen length and force.

[0077] 3. Calculate the elongation at break and tensile strength based on the test results and draw a chart. See Table 2 for details.

[0078] Table 2

[0079] tensile strength Elongation at break Example 1 0.209MPa 127% Example 2 0.102MPa 39% Example 3 0.156MPa 38% Example 4 0.188MPa 81% Example 5 0.110MPa 93% Example 6 0.132MPa 100% Example 7 0.110MPa 74% Example 8 0.123MPa 65% Comparative Example 1 0.080MPa 20%

[0080] It can be seen from the data in Table 2 that the tensile strength and elongation at break of the absorbing silicone gaskets of Examples 1-8 are better than those of the absorbing gaskets in the prior art, indicating that the absorbing silicone gaskets of the present application are more focused on application and achieve a longer service life.

[0081] It should be noted that, in the above embodiments, all powders are spherical except for the confirmed shape. In the reflection loss diagram, the thickness of the absorbing silicone gasket decreases from left to right.

[0082] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. An ultra-wideband, lightweight, microwave-absorbing silicone gasket, characterized in that: The invention is formed from the following raw materials in percentage by mass: 20wt%-40wt% of high viscosity vinyl silicone oil, 1wt%-5wt% of low viscosity vinyl silicone oil, 2wt%-20wt% of hydrogenated silicone oil, 0.2wt% of platinum catalyst, 5wt%-15wt% of soft magnetic absorbing powder, 15wt%-25wt% of dielectric absorbing powder, and 25wt%-40wt% of carbonyl iron absorbing powder; the soft magnetic absorbing powder is at least one of sendustine, iron nickel, and iron cobalt. One; the dielectric absorbing powder is at least one of barium titanate, silicon carbide, silicon nitride and iron nitride; the viscosity of the high-viscosity vinyl silicone oil is 1000-10000 cs, the viscosity of the low-viscosity vinyl silicone oil is 50-200 cs, and the viscosity of the hydrogenated silicone oil is 20-200 cs; the particle size of the soft magnetic absorbing powder is 50-200 μm; the particle size of the dielectric absorbing powder is 3-50 μm; and the particle size of the carbonyl iron absorbing powder is 3-50 μm.

2. The ultra-wideband, lightweight, microwave-absorbing silicone gasket according to claim 1, characterized in that: In terms of mass percentage, it is composed of the following raw materials: 33.7wt% high-viscosity vinyl silicone oil, 3wt% low-viscosity vinyl silicone oil, 3.1wt% hydrogenated silicone oil, 0.2wt% platinum catalyst, 10wt% soft magnetic absorbing powder, 20wt% dielectric absorbing powder, and 30wt% carbonyl iron absorbing powder.

3. The ultra-wideband, lightweight, microwave-absorbing silicone gasket according to claim 1 or 2, characterized in that: The high-viscosity vinyl silicone oil is at least one of terminal vinyl silicone oil, side vinyl silicone oil and terminal side vinyl silicone oil; the low-viscosity vinyl silicone oil is at least one of terminal vinyl silicone oil, side vinyl silicone oil and terminal side vinyl silicone oil; the hydrogen-containing silicone oil is at least one of terminal hydrogen-containing silicone oil and side hydrogen-containing silicone oil; and the platinum catalyst is a Karstedt catalyst.

4. The ultra-wideband, lightweight, microwave-absorbing silicone gasket according to claim 1 or 2, characterized in that: The sum of the mass percentages of the soft magnetic absorbing powder, the dielectric absorbing powder and the carbonyl iron absorbing powder is 50 wt % to 70 wt %.

5. The ultra-wideband, lightweight, microwave-absorbing silicone gasket according to claim 1 or 2, characterized in that: The shapes of the soft magnetic absorbing powder, the dielectric absorbing powder and the carbonyl iron absorbing powder are one or more of spherical, diamond, dendritic, flake and needle-shaped.

6. A method for preparing the ultra-wideband thin and light-weight microwave-absorbing silicone gasket according to claim 1, characterized in that: The following steps are involved: (1) Stirring: High-viscosity vinyl silicone oil, low-viscosity vinyl silicone oil, hydrogenated silicone oil and platinum catalyst are stirred uniformly in a vacuum; then soft magnetic absorbing powder, dielectric absorbing powder and carbonyl iron absorbing powder are added, stirred until there is no powder, and then stirred uniformly in a vacuum to obtain a mixed slurry of silicone oil and absorbing powder; (2) Calendering: Place the mixed slurry on release paper, cover the upper layer with release film, and use a calendering machine for calendering; then, vulcanize and form a semi-finished absorbing silicone gasket through a high-temperature drying oven; (3) Cutting: Cut the semi-finished microwave-absorbing silicone gasket after vulcanization molding to obtain a finished microwave-absorbing silicone gasket.

7. The method for preparing the ultra-wideband thin and light-weight microwave-absorbing silicone gasket according to claim 6, characterized in that: In step (1), the vacuum stirring time is 1-3 minutes; in step (2), the thickness of the release paper is 0.2-0.5 mm, the thickness of the centrifugal membrane is 20-100 μm, the length of the high-temperature drying tunnel is 8-12 m, the conveying speed is 0.5-1 m / min, and the temperature of the high-temperature drying tunnel is 80-120°C.

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