阅读说明：本技术 一种航空器用电磁屏蔽密封橡胶及其制备方法 (Electromagnetic shielding sealing rubber for aircraft and preparation method thereof ) 是由 栾婉莹 孙琦 吕银祥 于 2020-07-11 设计创作，主要内容包括：本发明属于电子材料领域,涉及一种电磁屏蔽密封橡胶的制备方法。本发明将介电损耗吸收型的碳材料和同时为反射损耗吸收型和磁损耗吸收型的金属,通过“芯-层”结构设计相结合,在尽可能降低高密度金属含量的情况下,获得高屏蔽效能、低密度电磁屏蔽橡胶。具有以下优点：(1)将磁性金属镍、铁与碳材料复合形成三元组分橡胶,大幅增加电磁屏蔽密封橡胶的电磁屏蔽效能(85.53 dB)。(2)以力学性能优异的碳纤维作为基底,提高电磁屏蔽橡胶的抗拉强度至359.2 MPa。(3)通过“芯-层”结构设计,并控制工艺条件,得到密度为1.42 g/cm<Sup>3</Sup>的低密度电磁屏蔽橡胶。(4)导电橡胶沿碳纤维布(芯层)经/纬夹角45o延伸,断裂伸长率为52.3%。(The invention belongs to the field of electronic materials, and relates to a preparation method of electromagnetic shielding sealing rubber. The invention combines the dielectric loss absorption type carbon material and the metal which is simultaneously a reflection loss absorption type metal and a magnetic loss absorption type metal through the structure design of a core-layer, and obtains the electromagnetic shielding rubber with high shielding efficiency and low density under the condition of reducing the content of the high-density metal as much as possible. Has the following advantages: (1) compounding magnetic metal nickel, iron and carbon material to form ternary materialThe component rubber greatly increases the electromagnetic shielding effectiveness (85.53 dB) of the electromagnetic shielding sealing rubber. (2) The carbon fiber with excellent mechanical property is used as a substrate, and the tensile strength of the electromagnetic shielding rubber is improved to 359.2 MPa. (3) Through the core-layer structure design and the control of the process conditions, the density of 1.42 g/cm is obtained 3 The low-density electromagnetic shielding rubber. (4) The conductive rubber extends along the warp/weft included angle of 45 degrees of the carbon fiber cloth (core layer), and the elongation at break is 52.3 percent.)

1. A preparation method of electromagnetic shielding sealing rubber for aircrafts comprises the following specific steps:

(1) surface modification treatment: soaking the carbon fiber cloth in a silane coupling agent solution for 10-30 minutes, and drying at the temperature of 120-150 ℃ for 10-30 minutes;

(2) metal ion adsorption and reduction: placing the carbon fiber subjected to surface modification treatment in the step (1) in a metal ion solution, soaking for 5-30 minutes, taking out, placing in a reducing agent solution, reducing for 5-30 minutes, taking out, and cleaning;

(3) co-deposition of metals: placing the carbon fiber fabric reduced in the step (2) in an alloy plating solution, performing chemical plating in a chemical plating solution at 65-85 ℃ for 30-90 minutes, and depositing a Ni-Fe-P alloy plating layer on the surface of the carbon fiber fabric; taking out, cleaning and drying to obtain the conductive fabric;

(4) compounding: mixing the A glue and the B glue of the silicon rubber in a ratio of 10: 1, wherein the A rubber refers to a silicon rubber monomer, and the B rubber refers to a curing agent; then dispersing the carbon nano-tubes in a mass fraction of 5-20 wt.%; uniformly coating the carbon fiber cloth on two sides of the conductive fabric obtained in the step (3) along the direction of the included angle of 45 degrees of warp/weft by using a coating method, so that the conductive rubber extends along the included angle of 45 degrees of warp/weft of the carbon fiber cloth and forms a product with the thickness of about 0.8-1.2 mm; curing for 3-5 hours at room temperature to obtain the electromagnetic shielding rubber.

2. The method according to claim 1, wherein the silane coupling agent solution is prepared by dissolving a silane coupling agent KH550 in an acetone solvent to obtain a solution having a molar concentration of 0.5 to 1.0 mol/L.

3. The preparation method according to claim 1, wherein the solvent of the metal ion solution is deionized water, the solute of the solution is nickel chloride, and the molar concentration of the metal ions is 0.5-1.0 mol/L.

4. The preparation method according to claim 1, wherein the solute of the reducing agent solution is sodium borohydride, the solvent is deionized water, and the molar concentration of the reducing agent is 0.5-1.0 mol/L.

5. The preparation method according to claim 1, wherein the solvent in the formulation of the alloy plating solution is deionized water, and various solutes in the solution are nickel chloride hexahydrate, ferrous chloride tetrahydrate, potassium sodium tartrate, sodium hypophosphite and ammonia water; wherein, the concentration of nickel chloride hexahydrate is 30-50g/L, the concentration of ferrous chloride tetrahydrate is 25-30g/L, the concentration of potassium sodium tartrate is 60-75g/L, the concentration of sodium hypophosphite is 25-30g/L, and the dosage of ammonia water is 50-70 mL/L.

6. An electromagnetic shielding sealing rubber for aircraft obtained by the preparation method of any one of claims 1 to 5, wherein the density, tensile strength, elongation at break and electromagnetic shielding effectiveness of the electromagnetic shielding sealing rubber meet the technical indexes of the electromagnetic shielding sealing rubber in the C919 large passenger plane project.

Technical Field

The invention belongs to the technical field of electronic materials, and particularly relates to electromagnetic shielding sealing rubber for an aircraft and a preparation method thereof.

Background

With the development of aviation technology, instruments for generating electromagnetic waves and electromagnetic ray interference to aircrafts in aviation systems are gradually increased. The use of a large amount of communication equipment, radars and other intensive electronic equipment makes the technical requirements of electromagnetic compatibility and electromagnetic shielding of aircraft higher and higher, and the high-performance shielding material is required to meet the normal working requirements of the aircraft, thereby improving the working strength of electronic equipment such as instruments and meters. The electromagnetic shielding sealing rubber is used as a functional material, has stable electromagnetic shielding performance, good physical and mechanical properties and excellent water vapor sealing performance, and is mainly applied to parts of an equipment cabin, a skin, a cover, electronic equipment and the like of an airplane. At present, the electromagnetic shielding sealing rubber mainly comprises doped rubber and layered rubber. The doped rubber means that a conductive filler (such as metal particles or a carbon-based conductive filler) is filled into a rubber matrix. When the metal with dominant reflection loss is used as a filler, the electromagnetic shielding rubber generally has electromagnetic shielding effectiveness, but the metal density is high, so that the requirement of light weight in an aviation system is difficult to meet. The preparation of silver-plated aluminum powder/methyl vinyl silicone rubber electromagnetic shielding conductive rubber by changing two-stage vulcanization process and researching its material property can obtain the invented product with good shielding effect greater than 80dB, breaking elongation greater than 185%, but its mechanical strength is lower, and its tensile strength is only 1.38 MPa. He Xiaotai et al (He Xiao Zheng, Houlin, Yi Hui, Chen Jian Bo. Special rubber products, 2013,34(04): 43-46.) studied silver-plated aluminum powder filled electromagnetic shielding rubber with silicon rubber substrate. When the using amount of the silver-plated aluminum powder is 260 parts, the rubber has stable conductivity and optimal comprehensive performance. The electromagnetic shielding rubber has shielding effectiveness of over 60dB, elongation at break of 150% and tensile strength of only 2.6 MPa. The carbon-based material doped rubber has good toughness and low density, but has insufficient conductivity, so that the requirement of high shielding efficiency (60-90 dB) of precision electronic equipment of aerospace equipment is difficult to meet. Zhao Yiwu et al (Zhao Yiwu, Zhouhua, Tianming, Zhang group, Li shu Rio. rubber industry 2015,62(01): 5-9.) prepare an electromagnetic shielding rubber with Ethylene Propylene Diene Monomer (EPDM) as a matrix and conductive carbon black as a conductive filler. Tests show that the elongation at break of the rubber can reach 232%, but the tensile strength is only 17.9 MPa, the electromagnetic shielding effectiveness is 26.89 dB, and the shielding capability is limited. Chiffon et al (chiffon, Fangqing rubber industry, 2018,65(08): 890-893.) adopt a mechanical blending method to prepare the conductive carbon black/eucommia rubber composite material, and study the influence of the conductive carbon black dosage on the conductivity and the electromagnetic shielding performance of the composite material. Researches show that when the using amount of the conductive carbon black is 20 parts, the maximum electromagnetic shielding effectiveness of the composite material reaches 33.2 dB, and the composite material can only meet the requirements of general industrial or commercial electronic equipment; elongation at break was 470% and tensile strength was only 22.0 MPa. Therefore, the doped rubber has certain defects, the uniformity of the filler is difficult to control, the vulcanization condition and the use of a coupling agent need to be controlled, and the mechanical property of the material is not high. In contrast, the layered rubber is simple to prepare, and only a rubber coating needs to be deposited on the surface of the flexible substrate with the electromagnetic shielding performance. The electromagnetic shielding flexible substrate is usually obtained by metalizing the surface of the fabric through the processes of chemical plating, electroplating, vacuum plating and the like, wherein the chemical plating is a common method for preparing the surface metalized fabric due to the characteristics of simple operation, low cost, compact and uniform chemical plating layer and the like. The surface metallized fabric is used as the middle layer of the layered rubber material, so that the mechanical property, the electromagnetic shielding efficiency, the heating property and the like of the electromagnetic shielding sealing rubber can be improved simultaneously.

The technical requirements of China C919 large passenger plane project on electromagnetic shielding sealing rubber are as follows: the density is less than or equal to 1.85g/cm³(ii) a The tensile strength is more than or equal to 350MPa, the elongation at break is more than or equal to 5 percent, the electromagnetic shielding effectiveness SE is more than or equal to 80dB, and the publicly reported rubber materials can only meet part of requirements and do not meet all the index requirements. The invention aims at the project requirement of a C919 large-scale passenger planeThe sealing rubber which meets all technical indexes is prepared through the core-layer structural design, the problem of neck clamping of a national important project is solved, the autonomy of key core materials is realized, and the sealing rubber has great significance.

The core technology of the invention lies in that the characteristics that carbon fiber and carbon nanotube are dielectric loss absorption type electromagnetic shielding material and magnetic metal is reflection loss type electromagnetic shielding material and magnetic loss absorption type electromagnetic shielding material are fully utilized, through the structural design of 'core-layer', the absorption loss is cooperated with the reflection loss, the dielectric loss is cooperated with the magnetic loss in the absorption loss, and under the condition of reducing the content of high-density metal as much as possible, high shielding efficiency and low rubber density are obtained; through structural design, the conductive rubber extends along the warp/weft included angle of 45 degrees of the carbon fiber cloth (core layer), the breaking elongation of the conductive rubber is greatly improved, and the defect that the breaking elongation of the conventional long-fiber carbon fiber conductive rubber is lower than 2% is overcome.

Disclosure of Invention

The invention aims to provide an electromagnetic shielding rubber which meets the specific technical requirements of an aircraft on the electromagnetic shielding sealing rubber and a preparation method thereof.

In the invention, the specific technical requirements of the aircraft on the electromagnetic shielding sealing rubber are as follows: the density is less than or equal to 1.85g/cm³The tensile strength is more than or equal to 350MPa, the breaking elongation is more than or equal to 5 percent, and the electromagnetic shielding effectiveness SE is more than or equal to 80 dB. Such as a C919 large passenger aircraft.

The invention combines two types of electromagnetic shielding materials, namely dielectric loss absorption type carbon material and metal which is reflection loss absorption type and magnetic loss absorption type at the same time, through a core-layer structure design to form absorption loss and reflection loss synergy, and dielectric loss and magnetic loss synergistic effect in the absorption loss, thereby obtaining high shielding efficiency and low rubber density under the condition of reducing the content of high-density metal as much as possible. The preparation method comprises the steps of taking the carbon fiber cloth as a substrate, depositing a Ni-Fe-P alloy coating on the surface of the carbon fiber cloth by utilizing a chemical plating process, and compounding the carbon nanotube doped silicone rubber layer on the surface of the coating. In the compounding process of the silicone rubber layer, through structural design, the silicone rubber is coated along the warp/weft included angle of 45 degrees of the conductive fabric, so that the conductive rubber extends along the warp/weft included angle of 45 degrees of the carbon fiber cloth (core layer), the elongation at break of the conductive rubber is greatly improved, and the defect that the elongation at break of the conventional long-fiber carbon fiber conductive rubber is lower than 2% is overcome. The plating process comprises surface modification, metal ion adsorption and reduction, metal codeposition and the like; the composite process includes coating method, in-situ polymerization, etc.

Through various tests such as density test, tensile property test (the tensile strength and the elongation at break are tested according to GB/T528-2009), electromagnetic shielding effectiveness test (the shielding effectiveness is tested according to GB/T12190-2006) and the like, the density of the electromagnetic shielding rubber is less than or equal to 1.85g/cm³The tensile strength is more than or equal to 350MPa, the elongation at break is more than or equal to 5 percent, the electromagnetic shielding effectiveness SE is more than or equal to 80dB, and the electromagnetic shielding rubber conforms to all technical requirements of C919 large passenger plane projects on electromagnetic shielding sealing rubber.

The preparation method of the electromagnetic shielding rubber provided by the invention comprises the following specific steps:

(1) surface modification treatment: soaking the carbon fiber cloth in a silane coupling agent solution for 10-30 minutes, and drying at the temperature of 120-150 ℃ for 10-30 minutes;

(2) metal ion adsorption and reduction: placing the carbon fiber subjected to surface modification treatment in the step (1) in a metal ion solution, soaking for 5-30 minutes, taking out, placing in a reducing agent solution, reducing for 5-30 minutes, taking out, and cleaning;

(3) co-deposition of metals: placing the carbon fiber fabric reduced in the step (2) in an alloy plating solution, performing chemical plating in a chemical plating solution at 65-85 ℃ for 30-90 minutes, and depositing a Ni-Fe-P alloy plating layer on the surface of the carbon fiber fabric; taking out, cleaning and drying to obtain the conductive fabric;

(4) compounding: mixing the A glue and the B glue of the silicon rubber in a ratio of 10: 1, wherein the A rubber refers to a silicon rubber monomer, and the B rubber refers to a curing agent; then dispersing the carbon nano-tubes in a mass fraction (wt.%) of 5-20%; uniformly coating the conductive rubber on two surfaces of the conductive fabric obtained in the step (3) along a warp/weft included angle of 45 degrees by using a coating method, so that the conductive rubber extends along a carbon fiber cloth (core layer) at a warp/weft included angle of 45 degrees and forms a product with the thickness of 0.8-1.2 mm; curing for 3-5 hours at room temperature to obtain the electromagnetic shielding rubber.

In the invention, the silane coupling agent solution for modifying the fabric surface is prepared by dissolving a silane coupling agent KH550 in an acetone solvent to obtain a solution with the molar concentration of 0.5-1.0 mol/L.

In the invention, the solvent of the metal ion solution is deionized water, the solute of the solution is nickel chloride, and the molar concentration of the metal ions is 0.5-2.0 mol/L.

In the invention, the solute of the reducing agent solution is sodium borohydride, the solvent is deionized water, and the molar concentration of the reducing agent is 0.5-1.0 mol/L.

In the invention, the solvent in the formula of the alloy plating solution is deionized water, and various solutes in the solution are nickel chloride hexahydrate, ferrous chloride tetrahydrate, potassium sodium tartrate, sodium hypophosphite and ammonia water; wherein the concentration of nickel chloride hexahydrate is 30-50g/L, the concentration of ferrous chloride tetrahydrate is 25-30g/L, the concentration of potassium sodium tartrate is 60-75g/L, the concentration of sodium hypophosphite is 20-30 g/L, and ammonia water (density is 0.91 g/cm)³) The dosage is 50-70 mL/L.

The electromagnetic shielding sealing rubber prepared by the invention meets the specific technical indexes: the density is less than or equal to 1.85g/cm³The tensile strength is more than or equal to 350MPa, the breaking elongation is more than or equal to 5 percent, and the electromagnetic shielding effectiveness SE is more than or equal to 80 dB. And has the following characteristics and advantages:

(1) the magnetic metal is a reflection loss type electromagnetic shielding material and a magnetic loss absorption type electromagnetic shielding material; magnetic metal iron is introduced into the system, so that the magnetism in the system is increased, and the matching of magnetic loss and dielectric loss of the carbon-based material is enhanced; the magnetic metal nickel, iron and carbon material are compounded, and compared with carbon-based material filled rubber (the shielding effectiveness is generally not more than 60 dB), the ternary component rubber greatly increases the electromagnetic shielding effectiveness (45.23-85.53 dB) of the electromagnetic shielding sealing rubber;

(2) carbon fibers with excellent mechanical properties are used as a substrate, and the rubber with a laminated structure is prepared by design; mechanical tests show that the tensile strength of the rubber with the layered structure is 359.2-383.5 MPa, and is improved by two orders of magnitude compared with filling type rubber;

(3) by means of core-layer structure design and reasonable control of chemical plating time and silicon rubber coating thickness in the preparation process, the density is lowered to 1.23-1.42 g/cm³The electromagnetic shielding rubber of (1);

(4) the conductive rubber extends along the warp/weft included angle of 45 degrees of the carbon fiber cloth (core layer), and mechanical tests show that the breaking elongation of the conductive rubber can reach 48.45-59.46%, and the defect that the breaking elongation of the conventional long-fiber carbon fiber conductive rubber is lower than 2% is overcome.

The electromagnetic shielding sealing rubber meets all technical indexes of C919 large passenger plane projects on the electromagnetic shielding sealing rubber. The electromagnetic shielding rubber prepared by the invention can be applied to electromagnetic shielding sealing rubber in an aviation system, is applied to the functions of shielding, protection, sealing and the like in an aircraft cabin, and has wide market prospect.

The invention has the beneficial effects that:

(1) the magnetic metal nickel, iron and carbon material are compounded to form ternary component rubber, so that the electromagnetic shielding effectiveness (85.53 dB) of the electromagnetic shielding sealing rubber is greatly improved;

(2) the carbon fiber with excellent mechanical property is used as a substrate, and the tensile strength of the electromagnetic shielding rubber is improved to 359.2 MPa;

(3) through the core-layer structure design and the control of the process conditions, the density of 1.42 g/cm is obtained³The low-density electromagnetic shielding rubber of (1);

(4) the conductive rubber extends along the warp/weft included angle of 45 degrees of the carbon fiber cloth (core layer), the elongation at break is 52.3 percent, the defect that the elongation at break of the conventional long-fiber carbon fiber conductive rubber is lower than 2 percent is overcome, and the conductive rubber is suitable for sealing materials. The electromagnetic shielding sealing rubber meets all technical indexes of C919 large passenger plane projects on the electromagnetic shielding sealing rubber;

(5) the process is simple and strong in operability, the preparation period is short, and the method is suitable for large-scale production and can meet the market demand.

Drawings

Fig. 1 is a flow chart of the preparation of the electromagnetic shielding sealing rubber.

Detailed Description

The invention is further described below by way of example.