Method for preparing high-stability conductive rubber based on modified silver-plated aluminum powder and application

Abstract

The invention relates to the technical field of polymer composite materials and flexible electronics, and provides a method for preparing high-stability conductive rubber based on modified silver-plated aluminum powder and application thereof.The method comprises the steps that firstly, the surface of the silver-plated aluminum powder is pretreated, then the pretreated silver-plated aluminum powder is subjected to step-by-step modification treatment to obtain the modified silver-plated aluminum powder, and then the modified silver-plated aluminum powder is subjected to step-by-step modification treatment to obtain the high-stability conductive rubber based on the modified silver-plated aluminum powder; the modified silver-plated aluminum powder is subjected to mixing and vulcanization forming, and the high-stability conductive rubber is obtained. According to the preparation method of the conductive rubber disclosed by the invention, relatively high silver-plated aluminum powder-rubber interface peel strength can be realized in the preparation process, the rubber powder bonding property is strong, and the compatibility is strong; after the conductive rubber is stretched for 1000 times, the resistance change rate is less than or equal to 20%; the vulcanization time is shortened by 30%-40% compared with that of a traditional process, and the adding amount of the filler can reach 60 wt% without affecting the processing fluidity.

Description

Technical Field

[0001] The present invention belongs to the field of polymer composite materials and flexible electronic technologies, and particularly relates to a method for preparing high-stability conductive rubber based on modified silver-plated aluminum powder and its application. Background Art

[0002] With the rapid development of flexible electronic technology, conductive rubber, as a core functional material, must simultaneously meet the following performance indicators: (1) High conductivity: Volume resistivity ≤1Ω·cm to ensure signal transmission efficiency; (2) Dynamic stability: After more than 1,000 stretching / bending times, the resistance change rate is ≤15%; (3) Processing compatibility: Even with a high filler content (>40wt%), it still has good mixing and vulcanization properties; (4) Environmental tolerance: It has resistance to moisture and heat (85℃ / 85% RH), oxidation resistance, and resistance to silver layer migration.

[0003] Existing silver-plated aluminum powder-based conductive rubbers are unable to meet the above requirements. The core bottleneck lies in the interface failure effect between the filler and the matrix. The main reasons are as follows:

[0004] (1) Weak physical bonding: Traditional silane coupling agents (such as KH-550) rely on physical adsorption and hydrogen bonding, have low bond energy (<50kJ / mol), and are easily desorbed under dynamic loads; (2) Single chemical bonding: A single coupling agent cannot simultaneously bond the metal silver layer to the rubber matrix, resulting in interfacial stress concentration; (3) Vulcanization inhibition effect: High filler content hinders the diffusion of rubber molecular chains, prolongs the vulcanization time, and reduces production efficiency.

[0005] Currently, academia and industry have proposed a variety of solutions to the above problems, but all of them have significant flaws:

[0006] 1. Nanosilver modification: Nanosilver dendrites are constructed on the surface of aluminum powder through chemical plating. Although the resistivity can be reduced to 0.5Ω·cm and the conductivity can be improved, the cost increases by 300% and the bending resistance is poor.

[0007] 2. Multiple coupling system: Titanate + silane coupling agent composite treatment is used (e.g., patent number: KR1020200078900A). However, since titanate needs to react in an alkaline environment and silane needs to react in an acidic environment, the pH range conflict limits the actual modification effect.

[0008] 3. Elastomer pre-grafting: Grafting elastic segments such as polyurethane on the filler surface (such as patent number: CN112280249A). Although it improves the interface flexibility, the grafting rate is low (<15%) and it will sacrifice conductivity, making the resistivity >2Ω·cm.

[0009] In view of this, this invention is proposed. Summary of the Invention

[0010] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a method and application for preparing high-stability conductive rubber based on modified silver-plated aluminum powder. By constructing a "metal-coupling agent-rubber" gradient interface structure, the resistance stability of the conductive rubber under dynamic deformation (stretching, bending, twisting) is significantly improved, and the core problems of insufficient interface bonding strength, low vulcanization efficiency and poor dynamic resistance stability under high filler content are solved.

[0011] The purpose of the present invention is to solve the problem through the following technical solutions:

[0012] In a first aspect, the present invention provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0013] S1. Pretreatment of silver-plated aluminum powder: placing silver-plated aluminum powder with a particle size of 20-60 μm and a silver content of 15-25% in a mixed solution containing a surfactant for ultrasonic cleaning, and then drying;

[0014] S2, step-by-step coupling modification:

[0015] The first step is mercaptosilane modification: the silver-plated aluminum powder pretreated with S1 is reacted with a mercaptan-silane coupling agent under acidic conditions to form a primary interface layer with Ag-S bonds. After the reaction is complete, the silver-plated aluminum powder is washed with alcohol and dried to obtain mercaptosilane-modified silver-plated aluminum powder.

[0016] The second step is aminosilane modification: the silver-plated aluminum powder modified with mercaptosilane is reacted with an aminosilane coupling agent under alkaline conditions to form a Si-O-Si bridged secondary interface layer. After the reaction is complete, the modified silver-plated aluminum powder is obtained after alcohol washing and drying.

[0017] Furthermore, the surfactant in S1 is one of sodium dodecylbenzenesulfonate, polyethylene glycol, OP-10 and polyvinylpyrrolidone K30, and the added amount of the surfactant accounts for 0.05-1% of the mass of the silver-plated aluminum powder;

[0018] The mass ratio of the solvent to water in the mixed solution is (3-10):1, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:(5-15), wherein the solvent is one of anhydrous ethanol or isopropyl alcohol.

[0019] Furthermore, in the ultrasonic cleaning in S1, the ultrasonic stirring frequency is 40-80 Hz, the stirring rate is 400-800 r / min, and the stirring time is 30-60 min;

[0020] The drying temperature is 60-80° C. and the drying time is 2-4 hours.

[0021] Furthermore, the specific steps of reacting the pretreated silver-plated aluminum powder with the thiol-silane coupling agent under acidic conditions in S2 are:

[0022] Weigh a certain amount of mercaptosilane coupling agent, dissolve it in an ethanol aqueous solution, add an acidic pH regulator, stir to fully hydrolyze it, and then add the washed and dried silver-plated aluminum powder for coupling modification;

[0023] The amount of the mercaptosilane coupling agent used accounts for 0.5-5% of the mass of the silver-plated aluminum powder;

[0024] The mercaptosilane coupling agent is one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and bis-[3-(triethoxysilyl)propyl]-tetrasulfide;

[0025] The ethanol aqueous solution is prepared from anhydrous ethanol and water, the mass ratio of anhydrous ethanol to water is 95: (1-10), and the mass ratio of the silver-plated aluminum powder to the ethanol aqueous solution is 1: (0.8-1.5);

[0026] The acidic pH regulator is one of acetic acid, hydrochloric acid and sulfuric acid, and the pH value is 3-6;

[0027] The hydrolysis temperature is 25-40° C., the stirring speed is 400-800 r / min, and the stirring time is 5-10 min. The coupling modification temperature is 25-40° C., the stirring speed is 400-800 r / min, and the modification time is 30-60 min.

[0028] Furthermore, the specific steps of reacting the mercaptosilane-modified silver-plated aluminum powder with the aminosilane coupling agent under alkaline conditions in S2 are:

[0029] Weigh a certain amount of aminosilane coupling agent, dissolve it in an ethanol aqueous solution, add an alkaline pH regulator, stir to fully hydrolyze it, and then add the silver-plated aluminum powder modified with mercaptosilane for coupling modification;

[0030] The amount of the aminosilane coupling agent is 0.5-5% of the mass of the silver-plated aluminum powder;

[0031] The aminosilane coupling agent is one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane and N-β-aminoethyl-γ-aminopropyltrimethoxysilane;

[0032] The ethanol aqueous solution is prepared from anhydrous ethanol and water, the mass ratio of anhydrous ethanol to water is 95: (1-10), and the mass ratio of the silver-plated aluminum powder to the ethanol aqueous solution is 1: (0.8-1.5);

[0033] The alkaline pH regulator is one of ammonia water, sodium hydroxide and potassium hydroxide, and the pH value is 7-9;

[0034] The hydrolysis temperature is 25-40° C., the stirring speed is 400-800 r / min, and the stirring time is 5-10 min. The coupling modification temperature is 25-40° C., the stirring speed is 400-800 r / min, and the modification time is 30-60 min.

[0035] Furthermore, the drying temperature in S2 is 60-80° C. and the drying time is 2-4 hours.

[0036] In a second aspect, the present invention provides a method for preparing a highly stable conductive rubber, wherein the modified silver-plated aluminum powder is prepared by a modification method, comprising the following steps:

[0037] Step 1: Mixing: After thinning the vinyl silicone rubber at 25±2°C, add 150-300 parts by mass of modified silver-plated aluminum powder, 1-5 parts by mass of vulcanizing agent and 1-5 parts by mass of auxiliary agent in batches and mix for 10-20 minutes;

[0038] Step 2: vulcanization molding to obtain high-stability conductive rubber.

[0039] Furthermore, the vinyl silicone rubber is Shin-Etsu Chemical KE-2005U or Dow Corning SE-6725U, the vulcanizing agent is bis(2,5-bis(2,4 ...

[0040] Furthermore, the vulcanization molding in step 2 is divided into two stages:

[0041] The temperature of the first stage vulcanization is 160-180℃, the vulcanization time is 8-15min, and the vulcanization pressure is 10-15MPa;

[0042] The temperature of the second stage vulcanization is 180-240℃, and the vulcanization time is 3-6h.

[0043] In a third aspect, the present invention provides a high-stability conductive rubber, which is prepared using the method for preparing high-stability conductive rubber. The conductive rubber is used to prepare flexible circuits, wearable medical sensors, or tactile skin for intelligent robots.

[0044] The conductive rubber has a volume resistivity of ≤0.005Ω·cm, a tensile strength of ≥1.5MPa, an elongation at break of ≥200%, and a resistivity change of less than 15% under 1000 dynamic loads.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. The present invention adopts step-by-step controllable coupling technology:

[0047] Thiol coupling agent preferential anchoring: a silane coupling agent containing a short-chain thiol group (such as 3-mercaptopropyltrimethoxysilane, KH590) is selected, which is hydrolyzed in an acidic environment of pH = 4-5 to generate -Si-OH, which is combined with the silver-plated layer through the Ag-S bond to form a dense monolayer;

[0048] Amino coupling agent bridging enhancement: Introducing a long-chain amino group silane coupling agent (such as N-aminoethyl-3-aminopropyltrimethoxysilane, KH792). Its diamino structure condenses with the remaining -Si-OH of the mercaptosilane to form a -Si-O-Si- network. On the other hand, it forms a covalent bond with the Si-OH of the silicone rubber through -NH2 and acts as an electron donor to promote the decomposition of the dipentadienyl vulcanizer.

[0049] Amine-catalyzed sulfurization reaction: (RO)3Si-(CH2)3-NH2+peroxide→free radical+NH3↑(RO)3Si-(CH2)3-NH2+peroxide→free radical+NH3↑;

[0050] Filler-matrix stress buffer design: By regulating the chain length ratio of mercaptan silane and aminosilane, a gradient modulus transition layer is formed in the interface area, effectively inhibiting crack propagation.

[0051] 2. The present invention achieves the following effects through the synergistic modification of thiols and amino coupling agents:

[0052] Interface strengthening: Ag-S bonds (bond energy 200kJ / mol) form a stable bond with the Si-O-Si network, improving the bonding strength;

[0053] Dynamic stability: amino group promotes vulcanization cross-linking, and the resistivity change is less than 15% after 1000 dynamic deformations;

[0054] Process compatibility: Under optimal parameters, the high-filler system still maintains good fluidity, meeting the needs of industrial production.

[0055] 3. The scientific value of the thiol-amino double coupling synergistic strategy proposed in this invention lies in: ① Chemical bond directional design: utilizing the strong bonding between -SH and Ag (Ag-S bond energy reaches 200kJ / mol) and the covalent bond / hydrogen bond between -NH2 and Si-OH to achieve the interfacial binding energy increased from <50kJ / mol in the traditional system to >150kJ / mol; ② Dynamic network self-repair: dissipating deformation stress through molecular slippage of long chain segments of the coupling agent (such as the propyl chain of KH590), thereby reducing permanent damage to the conductive network. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the invention.

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0058] Figure 1 This is a flow chart of the modification method of the silver-plated aluminum powder of the present invention;

[0059] Figure 2 This is a flow chart of the method for preparing high-stability conductive rubber according to the present invention. DETAILED DESCRIPTION

[0060] Exemplary embodiments will be described in detail herein, with examples illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements, unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Instead, they are merely examples consistent with certain aspects of the present invention as detailed in the appended claims.

[0061] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0062] The present invention provides a modification method of silver-plated aluminum powder, referring to Figure 1 As shown, the following steps are included:

[0063] S1. Pretreatment of silver-plated aluminum powder.

[0064] Materials and parameter ranges:

[0065] Silver-plated aluminum powder has a particle size of 20-60 μm, a silver content of 15-25%, and a spherical shape. The manufacturer is Beijing Zhongxin Ruifu Material Technology Co., Ltd.; the water involved in the following is ultrapure water, and the ultrapure water used is deionized water or distilled water; all chemical reagents used are analytical grade unless otherwise specified.

[0066] Powder surface cleaning: Weigh a certain amount of surfactant and dissolve it in a mixed solution of solvent and water. After it is completely dissolved, weigh a certain amount of silver-plated aluminum powder with a particle size of 20-60 μm and a silver content of 15-25% and place it in the mixed solution containing the surfactant and perform ultrasonic stirring. After the cleaning is completed, wash it repeatedly twice and filter it to remove residual impurities, then place it in an oven to dry for later use.

[0067] Specifically, the mass ratio of the solvent to water is (3-10):1, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:(5-15). The solvent is anhydrous ethanol (purity ≥99.7%) or isopropyl alcohol (purity ≥99.5%), preferably anhydrous ethanol, which has the advantages of low cost and fast volatilization.

[0068] The surfactant is one of sodium dodecylbenzenesulfonate (SDBS), polyethylene glycol, OP-10 and polyvinyl pyrrolidone k30 (PVPk30), preferably sodium dodecylbenzenesulfonate; the added amount of the surfactant accounts for 0.05-1% of the mass of the silver-plated aluminum powder, preferably, the added amount of the surfactant accounts for 0.1-0.5% of the mass of the silver-plated aluminum powder.

[0069] During ultrasonic cleaning, the ultrasonic stirring frequency is 40-80 Hz, the stirring rate is 400-800 r / min, and the stirring time is 30-60 min; the drying temperature is 60-80° C., and the drying time is 2-4 h.

[0070] S2. Step-by-step coupling modification treatment.

[0071] Materials and parameter ranges: The water involved in the following is all ultrapure water, which is deionized water or distilled water; all chemical reagents used are analytical grade unless otherwise specified.

[0072] The first step is mercaptosilane modification: weigh a certain amount of mercaptosilane coupling agent, dissolve it in a certain amount of ethanol aqueous solution, add an acidic pH regulator, stir to fully hydrolyze it, and then add the silver-plated aluminum powder pretreated with S1 for coupling modification to form a primary interface layer with Ag-S bonds. After the reaction is complete, wash it with alcohol repeatedly twice and filter it to remove residual impurities. Then place it in an oven to dry to obtain mercaptosilane-modified silver-plated aluminum powder for use.

[0073] Specifically, the amount of the mercaptosilane coupling agent is 0.5-5% of the mass of the silver-plated aluminum powder, preferably, the amount of the mercaptosilane coupling agent is 1-3.5% of the mass of the silver-plated aluminum powder; the mercaptosilane coupling agent is one of 3-mercaptopropyltrimethoxysilane (KH590, purity ≥98%), 3-mercaptopropyltriethoxysilane (KH580, purity ≥95%) and bis-[3-(triethoxysilyl)propyl]-tetrasulfide (Si-69, purity ≥97%), preferably 3-mercaptopropyltrimethoxysilane (KH590, purity ≥98%).

[0074] The ethanol aqueous solution used is prepared from anhydrous ethanol and water, the mass ratio of anhydrous ethanol to water is 95:(1-10), preferably, the mass ratio of anhydrous ethanol to water is 95:5; the mass ratio of silver-plated aluminum powder to ethanol aqueous solution is 1:(0.8-1.5), preferably, the mass ratio of silver-plated aluminum powder to ethanol aqueous solution is 1:1; the acidic pH regulator is one of acetic acid, hydrochloric acid and sulfuric acid, and the pH value is between 3-6. Preferably, acetic acid is used to adjust the pH value to 3.5-5.5.

[0075] The hydrolysis step is performed at a temperature of 25-40°C, a stirring speed of 400-800 r / min, and a stirring time of 5-10 minutes. The coupling modification step is performed at a temperature of 25-40°C, a stirring speed of 400-800 r / min, and a modification time of 30-60 minutes. The product is dried in an oven at a temperature of 60-80°C and a drying time of 2-4 hours.

[0076] The second step is aminosilane modification:

[0077] A certain amount of aminosilane coupling agent was weighed and dissolved in a certain amount of ethanol aqueous solution. An alkaline pH regulator was added and stirred to fully hydrolyze it. Then, the silver-plated aluminum powder modified with the mercaptosilane in the first step was added for coupling modification to form a Si-O-Si bridged secondary interface layer. After the reaction was complete, the mixture was repeatedly washed with alcohol twice and filtered to remove residual impurities. The mixture was then dried in an oven to obtain the modified silver-plated aluminum powder for later use.

[0078] Specifically, the amount of the aminosilane coupling agent is 0.5-5% of the mass of the silver-plated aluminum powder, preferably, the amount of the aminosilane coupling agent is 2-4% of the mass of the silver-plated aluminum powder; the aminosilane coupling agent is one of γ-aminopropyltriethoxysilane (KH550, purity ≥95%), γ-aminopropyltrimethoxysilane (KH560, purity ≥95%) and N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792, purity ≥95%), preferably N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH792, purity ≥95%).

[0079] The ethanol aqueous solution used is prepared from anhydrous ethanol and water, the mass ratio of anhydrous ethanol to water is 95:(1-10), preferably, the mass ratio of anhydrous ethanol to water is 95:5; the mass ratio of silver-plated aluminum powder to ethanol aqueous solution is 1:(0.8-1.5), preferably, the mass ratio of silver-plated aluminum powder to ethanol aqueous solution is 1:1; the alkaline pH regulator is one of ammonia water, sodium hydroxide and potassium hydroxide, the pH value is 7-9, preferably ammonia water, and the pH value is adjusted to 7-8.

[0080] The temperature in the hydrolysis step is set to 25-40°C, the stirring speed is 400-800 r / min, and the stirring time is 5-10 min; the temperature in the coupling modification step is set to 25-40°C, the stirring speed is 400-800 r / min, and the modification time is 30-60 min; and the drying treatment is carried out in an oven at a temperature of 60-80°C and a time of 2-4 h.

[0081] The present invention provides a method for preparing a high-stability conductive rubber, wherein the modified silver-plated aluminum powder prepared by the modification method is Figure 2 As shown, the following steps are included:

[0082] Step 1, mixing: in a two-roll mill, pass the vinyl silicone rubber thinly 3-5 times at 25±2°C with a roll distance of 0.5mm, add 150-300 parts by mass, preferably 200-250 parts by mass, of the modified silver-plated aluminum powder in 4 times, with an interval of 5 minutes each time; then add 1-5 parts by mass of vulcanizing agent and 1-5 parts by mass of auxiliary agent in sequence, and mix for 10-20 minutes.

[0083] Specifically, the vinyl silicone rubber is Shin-Etsu Chemical KE-2005U or Dow Corning SE-6725U, preferably Shin-Etsu Chemical KE-2005U, which has the advantages of fast vulcanization rate and balanced mechanical properties; the vulcanizing agent is bis(25-24) or bis(24-25), preferably bis(25-25), with a mass fraction of 1.5-3.5 parts, which has the advantage of high vulcanization efficiency; the auxiliary agent is hydroxy silicone oil (viscosity of 500-1000mPa·s) or zinc stearate (lubricant), preferably hydroxy silicone oil, with a mass fraction of 1-3 parts.

[0084] Step 2: vulcanization molding to obtain high-stability conductive rubber.

[0085] Specifically, vulcanization molding is divided into two stages, namely, the vulcanization sheeting process;

[0086] The temperature of the first stage vulcanization is 160-180°C, the vulcanization time is 8-15 minutes, and the vulcanization pressure is 10-15 MPa. The preferred temperature is 160°C, the vulcanization time is 12 minutes, and the vulcanization pressure is 12 MPa.

[0087] The temperature of the second stage vulcanization is 180-240°C, and the vulcanization time is 3-6 hours, preferably 200°C and 4 hours. The purpose of the second stage vulcanization is to eliminate residual stress.

[0088] The highly stable conductive rubber prepared using the method of the present invention is suitable for applications requiring extremely high mechanical durability, such as flexible circuits, wearable medical sensors, and intelligent robot tactile skin. By constructing a gradient interface structure of "metal-coupling agent-rubber," the invention significantly improves the conductive rubber's resistance stability under dynamic deformation (stretching, bending, and twisting). The conductive rubber has a volume resistivity of ≤0.005Ω·cm, a tensile strength of ≥1.5MPa, and an elongation at break of ≥200%. The resistivity change after 1000 dynamic load cycles is less than 15%.

[0089] In order to verify the beneficial effects of the modification method of the present invention, the following examples are provided to further illustrate the effects.

[0090] Example 1

[0091] This embodiment provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0092] S1. Pretreatment of silver-plated aluminum powder.

[0093] Powder surface cleaning: Weigh 0.3 parts by mass of sodium dodecylbenzenesulfonate and dissolve it in a mixed solution of solvent and water, wherein the solvent is anhydrous ethanol, and the mass ratio of anhydrous ethanol to water is 4:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 40 μm and a silver content of 20% and place it in a mixed solution containing a surfactant, and the mass ratio of silver-plated aluminum powder to the mixed solution is 1:5. Ultrasonic stirring is performed, the ultrasonic frequency is 60 Hz, the stirring rate is 500 r / min, and the stirring time is 30 min. After cleaning is completed, it is repeatedly washed twice and filtered to remove residual impurities, and then placed in an oven at 80°C for 3 h for standby use.

[0094] S2. Step-by-step coupling modification treatment.

[0095] The first step is mercaptosilane modification: 1.5 parts by mass of KH590 is weighed and dissolved in an ethanol aqueous solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 5 parts by mass of water. Acetic acid is added to adjust the pH to 4-4.5, the hydrolysis temperature is set to 30°C, the stirring speed is 500r / min, and the hydrolysis is carried out for 10 minutes; then 100 parts by mass of cleaned silver-plated aluminum powder is added for coupling modification. The mass ratio of the cleaned silver-plated aluminum powder to the ethanol aqueous solution is 1:1. The water bath temperature is set to 30°C and the stirring speed is 500r / min. After reacting for 40 minutes, the mixture is repeatedly washed with alcohol twice and filtered to remove residual impurities. It is then placed in an oven and dried at 60°C for 4 hours for standby use.

[0096] The second step is aminosilane modification: 2.5 parts by mass of KH792 are weighed and dissolved in an ethanol aqueous solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 5 parts by mass of water. Ammonia water is added to adjust the pH to 7.5-8, the hydrolysis temperature is set to 30°C, the stirring speed is 500r / min, and the hydrolysis is carried out for 10 minutes; then 100 parts by mass of mercaptosilane-modified silver-plated aluminum powder is added for coupling modification. The mass ratio of silver-plated aluminum powder to ethanol aqueous solution is 1:1, the hydrolysis temperature is set to 30°C, the stirring speed is 500r / min, and after reacting for 40 minutes, the powder is repeatedly washed with alcohol twice and filtered to remove residual impurities. It is then placed in an oven and dried at 60°C for 4 hours to obtain the modified silver-plated aluminum powder for standby use.

[0097] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0098] 100 parts by mass of KE-2005U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thin-passed 4 times (roller spacing 0.5 mm); 220 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 3 parts by mass of vulcanizing agent and 2 parts by mass of hydroxy silicone oil were added in sequence and mixed for 5 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 160°C, the vulcanization time was 12 minutes, and the vulcanization pressure was 12 MPa; the second stage vulcanization temperature was 200°C, the vulcanization time was 4 hours, and the performance test was shown in Table 1.

[0099] Example 2

[0100] This embodiment provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0101] S1. Pretreatment of silver-plated aluminum powder.

[0102] Powder surface cleaning: Weigh 0.1 parts by mass of sodium dodecylbenzenesulfonate and dissolve it in a mixed solution of solvent and water, wherein the solvent is anhydrous ethanol, and the mass ratio of anhydrous ethanol to water is 3:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 20 μm and a silver content of 15% and place it in a mixed solution containing a surfactant, and the mass ratio of silver-plated aluminum powder to the mixed solution is 1:10. Ultrasonic stirring is performed, the ultrasonic frequency is 40 Hz, the stirring rate is 400 r / min, and the stirring time is 60 min. After cleaning is completed, it is repeatedly washed twice and filtered to remove residual impurities, and then placed in an oven at 60°C for 4 hours for use.

[0103] S2. Step-by-step coupling modification treatment.

[0104] The first step is mercaptosilane modification: 3.5 parts by mass of KH590 are weighed and dissolved in an ethanol aqueous solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 1 part by mass of water. Acetic acid is added to adjust the pH to 3.5-4, the hydrolysis temperature is set to 25°C, the stirring speed is 400r / min, and the hydrolysis is carried out for 10 minutes; then 100 parts by mass of cleaned silver-plated aluminum powder are added for coupling modification, the mass ratio of the cleaned silver-plated aluminum powder to the ethanol aqueous solution is 1:0.8, the water bath temperature is set to 25°C, the stirring speed is 400r / min, and after reacting for 60 minutes, the mixture is repeatedly washed with alcohol twice and filtered to remove residual impurities, and then placed in an oven at 60°C for drying for 3 hours.

[0105] The second step is aminosilane modification: 0.5 parts by mass of KH792 is weighed and dissolved in an ethanol aqueous solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 1 part by mass of water. Ammonia water is added to adjust the pH to 7-7.5, the hydrolysis temperature is set to 25°C, the stirring speed is 400r / min, and the hydrolysis is carried out for 10 minutes; then 100 parts by mass of mercaptosilane-modified silver-plated aluminum powder is added for coupling modification. The mass ratio of silver-plated aluminum powder to ethanol aqueous solution is 1:0.8, the hydrolysis temperature is set to 25°C, the stirring speed is 400r / min, and after reacting for 60 minutes, the powder is repeatedly washed with alcohol twice and filtered to remove residual impurities. It is then placed in an oven and dried at 70°C for 3 hours to obtain the modified silver-plated aluminum powder for standby use.

[0106] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0107] 100 parts by mass of KE-2005U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thinly passed 3 times (roller spacing 0.5 mm); 150 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 2 parts by mass of vulcanizing agent and 5 parts by mass of hydroxy silicone oil were added in sequence and mixed for 8 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 170°C, the vulcanization time was 8 minutes, and the vulcanization pressure was 10 MPa; the second stage vulcanization temperature was 180°C, the vulcanization time was 6 hours, and the performance test was shown in Table 1.

[0108] Example 3

[0109] This embodiment provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0110] S1. Pretreatment of silver-plated aluminum powder.

[0111] Powder surface cleaning: Weigh 0.5 parts by mass of polyethylene glycol and dissolve it in a mixed solution of solvent and water, wherein the solvent is anhydrous ethanol, and the mass ratio of anhydrous ethanol to water is 10:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 60 μm and a silver content of 25% and place it in a mixed solution containing a surfactant. The mass ratio of silver-plated aluminum powder to the mixed solution is 1:15. Ultrasonic stirring is performed, the ultrasonic frequency is 80 Hz, the stirring rate is 800 r / min, and the stirring time is 30 min. After cleaning is completed, it is repeatedly washed twice and filtered to remove residual impurities, and then placed in an oven at 70°C for 3 h for use.

[0112] S2. Step-by-step coupling modification treatment.

[0113] The first step is mercaptosilane modification: 4 parts by mass of KH580 are weighed and dissolved in an ethanol aqueous solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 10 parts by mass of water. Acetic acid is added to adjust the pH to 4.5-5.5, the hydrolysis temperature is set to 40°C, the stirring speed is 800r / min, and the hydrolysis is carried out for 5 minutes; then 100 parts by mass of cleaned silver-plated aluminum powder are added for coupling modification, the mass ratio of the cleaned silver-plated aluminum powder to the ethanol aqueous solution is 1:1.5, the water bath temperature is set to 40°C, the stirring speed is 800r / min, and after reacting for 30 minutes, the mixture is repeatedly washed with alcohol twice and filtered to remove residual impurities, and then placed in an oven at 80°C for drying for 2 hours.

[0114] The second step is aminosilane modification: 4 parts by mass of KH792 are weighed and dissolved in an ethanol aqueous solution, the ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 10 parts by mass of water, ammonia water is added to adjust the pH to 7.5-9, the hydrolysis temperature is set to 40°C, the stirring speed is 800r / min, and the hydrolysis is carried out for 5 minutes; then 100 parts by mass of mercaptosilane-modified silver-plated aluminum powder is added for coupling modification, the hydrolysis temperature is set to 40°C, the stirring speed is 800r / min, and after reacting for 30 minutes, the mixture is repeatedly washed with alcohol twice and filtered to remove residual impurities, and then placed in an oven and dried at 80°C for 2 hours to obtain the modified silver-plated aluminum powder for standby use.

[0115] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0116] 100 parts by mass of KE-2005U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thin-passed 5 times (roller spacing 0.5 mm); 300 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 5 parts by mass of vulcanizing agent and 1 part by mass of hydroxy silicone oil were added in sequence and mixed for 10 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 180°C, the vulcanization time was 15 minutes, and the vulcanization pressure was 15 MPa; the second stage vulcanization temperature was 240°C, the vulcanization time was 3 hours, and the performance test was shown in Table 1.

[0117] Example 4

[0118] This embodiment provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0119] S1. Pretreatment of silver-plated aluminum powder.

[0120] Powder surface cleaning: Weigh 1 part by mass of polyethylene glycol and dissolve it in a mixed solution of solvent and water, wherein the solvent is isopropyl alcohol, and the mass ratio of isopropyl alcohol to water is 5:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 40 μm and a silver content of 25% and place it in a mixed solution containing a surfactant, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:5. Ultrasonic stirring is performed, the ultrasonic frequency is 80 Hz, the stirring rate is 800 r / min, and the stirring time is 30 min. After the cleaning is completed, it is repeatedly washed twice and filtered to remove residual impurities, and then placed in an oven at 80°C for 2 h for use.

[0121] S2. Step-by-step coupling modification treatment.

[0122] The first step is mercaptosilane modification: 2.5 parts by mass of KH590 are weighed and dissolved in an alcohol-water solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 10 parts by mass of water. Acetic acid is added to adjust the pH to 4.5-5.5, the hydrolysis temperature is set to 40°C, the stirring speed is 600r / min, and the hydrolysis is carried out for 8 minutes; then 100 parts by mass of cleaned silver-plated aluminum powder are added for coupling modification. The mass ratio of the cleaned silver-plated aluminum powder to the ethanol-water solution is 1:1. The water bath temperature is set to 40°C and the stirring speed is 800r / min. After reacting for 30 minutes, the solution is repeatedly washed with alcohol twice and filtered to remove residual impurities. It is then placed in an oven and dried at 80°C for 2 hours for standby use.

[0123] The second step is aminosilane modification: 3.5 parts by mass of KH550 are weighed and dissolved in an ethanol aqueous solution, the ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 10 parts by mass of water, ammonia water is added to adjust the pH to 7.5-9, the hydrolysis temperature is set to 30°C, the stirring speed is 600r / min, and the hydrolysis is carried out for 8 minutes; then 100 parts by mass of mercaptosilane-modified silver-plated aluminum powder is added for coupling modification, the hydrolysis temperature is set to 25°C, the stirring speed is 600r / min, and after reacting for 30 minutes, the mixture is repeatedly washed with alcohol twice and filtered to remove residual impurities, and then placed in an oven and dried at 80°C for 2 hours to obtain the modified silver-plated aluminum powder for standby use.

[0124] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0125] 100 parts by mass of SE-6725U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thin-passed 5 times (roller spacing 0.5 mm); 300 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 5 parts by mass of vulcanizing agent and 1 part by mass of hydroxy silicone oil were added in sequence and mixed for 10 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 180°C, the vulcanization time was 15 minutes, and the vulcanization pressure was 15 MPa; the second stage vulcanization temperature was 240°C, the vulcanization time was 3 hours, and the performance test was shown in Table 1.

[0126] Example 5

[0127] This embodiment provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0128] S1. Pretreatment of silver-plated aluminum powder.

[0129] Powder surface cleaning: Weigh 1 part by mass of OP-10 and dissolve it in a mixed solution of solvent and water, wherein the solvent is isopropyl alcohol, and the mass ratio of isopropyl alcohol to water is 3:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 20 μm and a silver content of 20% and place it in a mixed solution containing a surfactant, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:10. Ultrasonic stirring is performed, the ultrasonic frequency is 80 Hz, the stirring rate is 800 r / min, and the stirring time is 30 min. After cleaning is completed, it is repeatedly washed twice and filtered to remove residual impurities, and then placed in an oven at 80°C for 2 h for standby use.

[0130] S2. Step-by-step coupling modification treatment.

[0131] The first step is mercaptosilane modification: 2.5 parts by mass of KH580 are weighed and dissolved in an alcohol-water solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 10 parts by mass of water. Hydrochloric acid is added to adjust the pH to 4.5-5.5, the hydrolysis temperature is set to 40°C, the stirring speed is 600r / min, and the hydrolysis is carried out for 8 minutes; then 100 parts by mass of cleaned silver-plated aluminum powder are added for coupling modification, the mass ratio of the cleaned silver-plated aluminum powder to the ethanol-water solution is 1:1, the water bath temperature is set to 40°C, the stirring speed is 800r / min, and after reacting for 30 minutes, the solution is repeatedly washed with alcohol twice and filtered to remove residual impurities, and then placed in an oven at 80°C for drying for 2 hours.

[0132] The second step is aminosilane modification: 3.5 parts by mass of KH560 are weighed and dissolved in an ethanol aqueous solution, the ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 10 parts by mass of water, sodium hydroxide is added to adjust the pH to 7.5-9, the hydrolysis temperature is set to 30°C, the stirring speed is 600r / min, and the hydrolysis is carried out for 8 minutes; then 100 parts by mass of mercaptosilane-modified silver-plated aluminum powder is added for coupling modification, the hydrolysis temperature is set to 25°C, the stirring speed is 600r / min, and after reacting for 30 minutes, the mixture is repeatedly washed with alcohol twice and filtered to remove residual impurities, and then placed in an oven and dried at 80°C for 2 hours to obtain the modified silver-plated aluminum powder for standby use.

[0133] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0134] 100 parts by mass of SE-6725U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thin-passed 5 times (roller spacing 0.5 mm); 250 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 5 parts by mass of vulcanizing agent and 1 part by mass of hydroxy silicone oil were added in sequence and mixed for 10 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 180°C, the vulcanization time was 15 minutes, and the vulcanization pressure was 15 MPa; the second stage vulcanization temperature was 240°C, the vulcanization time was 3 hours, and the performance test was shown in Table 1.

[0135] Example 6

[0136] This embodiment provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0137] S1. Pretreatment of silver-plated aluminum powder.

[0138] Powder surface cleaning: Weigh 0.5 parts by mass of polyvinyl pyrrolidone K30 and dissolve it in a mixed solution of solvent and water, wherein the solvent is isopropyl alcohol, and the mass ratio of isopropyl alcohol to water is 5:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 20 μm and a silver content of 20% and place it in a mixed solution containing a surfactant, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:10. Perform ultrasonic stirring, the ultrasonic frequency is 80 Hz, the stirring rate is 800 r / min, and the stirring time is 30 min. After cleaning is completed, wash it repeatedly twice and filter it to remove residual impurities, then place it in an oven at 80°C to dry for 2 h for use.

[0139] S2. Step-by-step coupling modification treatment.

[0140] The first step is mercaptosilane modification: 2.5 parts by mass of Si-69 is weighed and dissolved in an ethanol aqueous solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 5 parts by mass of water. Sulfuric acid is added to adjust the pH to 4.5-5.5, the hydrolysis temperature is set to 40°C, the stirring speed is 600r / min, and the hydrolysis is carried out for 8 minutes; then 100 parts by mass of cleaned silver-plated aluminum powder is added for coupling modification, the mass ratio of the cleaned silver-plated aluminum powder to the ethanol aqueous solution is 1:1, the water bath temperature is set to 40°C, the stirring speed is 800r / min, and after reacting for 30 minutes, the mixture is repeatedly washed with alcohol twice for filtration to remove residual impurities, and then placed in an oven at 80°C for drying for 2 hours.

[0141] The second step is aminosilane modification: 3.5 parts by mass of KH792 are weighed and dissolved in an ethanol aqueous solution, the ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 10 parts by mass of water, potassium hydroxide is added to adjust the pH to 7.5-9, the hydrolysis temperature is set to 30°C, the stirring speed is 600r / min, and the hydrolysis is carried out for 8 minutes; then 100 parts by mass of mercaptosilane-modified silver-plated aluminum powder is added for coupling modification, the hydrolysis temperature is set to 25°C, the stirring speed is 600r / min, and after reacting for 30 minutes, the mixture is repeatedly washed with alcohol twice and filtered to remove residual impurities, and then placed in an oven and dried at 80°C for 2 hours to obtain the modified silver-plated aluminum powder for standby use.

[0142] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0143] 100 parts by mass of SE-6725U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thin-passed 4 times (roller spacing 0.5 mm); 256 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 5 parts by mass of vulcanizing agent and 1 part by mass of zinc stearate were added in sequence and mixed for 10 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 180°C, the vulcanization time was 8 minutes, and the vulcanization pressure was 15 MPa; the second stage vulcanization temperature was 200°C, the vulcanization time was 4 hours, and the performance test was shown in Table 1.

[0144] Comparative Example 1

[0145] This comparative example provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0146] S1. Pretreatment of silver-plated aluminum powder.

[0147] Powder surface cleaning: Weigh 0.3 parts by mass of sodium dodecylbenzenesulfonate and dissolve it in a mixed solution of solvent and water, wherein the solvent is anhydrous ethanol, and the mass ratio of anhydrous ethanol to water is 4:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 40 μm and a silver content of 20% and place it in a mixed solution containing a surfactant, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:10. Ultrasonic stirring is performed, the ultrasonic frequency is 60 Hz, the stirring rate is 500 r / min, and the stirring time is 30 min. After cleaning is completed, it is repeatedly washed twice and filtered to remove residual impurities, and then placed in an oven at 80°C for 2 h for standby use.

[0148] S2. Modification treatment.

[0149] Mercaptosilane modification: 1.5 parts by mass of KH590 was weighed and dissolved in an ethanol aqueous solution. The ethanol solution was prepared by 95 parts by mass of anhydrous ethanol and 5 parts by mass of water. The pH was adjusted to 4.5-5.5 with acetic acid. The hydrolysis temperature was set to 30°C, the stirring speed was 500r / min, and the hydrolysis was carried out for 10 minutes. Then 100 parts by mass of cleaned silver-plated aluminum powder was added for coupling modification. The mass ratio of the cleaned silver-plated aluminum powder to the ethanol aqueous solution was 1:1. The water bath temperature was set to 30°C, the stirring speed was 500r / min, and after reacting for 40 minutes, the powder was repeatedly washed with alcohol twice and filtered to remove residual impurities. The powder was then placed in an oven and dried at 60°C for 3 hours to obtain the modified silver-plated aluminum powder for standby use.

[0150] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0151] 100 parts by mass of KE-2005U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thin-passed 4 times (roller spacing 0.5 mm); 220 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 3 parts by mass of vulcanizing agent and 2 parts by mass of hydroxy silicone oil were added in sequence and mixed for 5 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 160°C, the vulcanization time was 12 minutes, and the vulcanization pressure was 12 MPa; the second stage vulcanization temperature was 200°C, the vulcanization time was 4 hours, and the performance test was shown in Table 1.

[0152] Comparative Example 2

[0153] This comparative example provides a method for modifying silver-plated aluminum powder, comprising the following steps:

[0154] S1. Pretreatment of silver-plated aluminum powder.

[0155] Powder surface cleaning: Weigh 0.3 parts by mass of sodium dodecylbenzenesulfonate and dissolve it in a mixed solution of solvent and water, wherein the solvent is anhydrous ethanol, and the mass ratio of anhydrous ethanol to water is 4:1. After complete dissolution, weigh 100 parts by mass of silver-plated aluminum powder with a particle size of 40 μm and a silver content of 20% and place it in a mixed solution containing a surfactant, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:10. Ultrasonic stirring is performed, the ultrasonic frequency is 60 Hz, the stirring rate is 500 r / min, and the stirring time is 30 min. After cleaning is completed, it is repeatedly washed twice and filtered to remove residual impurities, and then placed in an oven at 80°C for 2 h for standby use.

[0156] S2. Modification treatment.

[0157] Aminosilane modification: Weigh 2.5 parts by mass of KH792 and dissolve it in an ethanol aqueous solution. The ethanol solution is prepared by 95 parts by mass of anhydrous ethanol and 5 parts by mass of water. Add ammonia water to adjust the pH to 7.5-8, set the hydrolysis temperature to 30°C, the stirring speed to 500 r / min, and hydrolyze for 10 minutes; then add 100 parts by mass of cleaned silver-plated aluminum powder for coupling modification, set the hydrolysis temperature to 30°C, the stirring speed to 500 r / min, react for 40 minutes, and then repeatedly wash with alcohol twice for filtration to remove residual impurities. Then place it in an oven and dry it at 60°C for 3 hours to obtain the modified silver-plated aluminum powder for standby use.

[0158] This embodiment adopts the method for preparing high-stability conductive rubber to prepare conductive rubber, including the following steps:

[0159] 100 parts by mass of KE-2005U silicone rubber were added to a two-roll mill (roller temperature 25±2°C) and thin-passed 4 times (roller spacing 0.5 mm); 220 parts by mass of modified silver-plated aluminum powder were weighed and added in 4 times, with an interval of 5 minutes each time; then 3 parts by mass of vulcanizing agent and 2 parts by mass of hydroxy silicone oil were added in sequence and mixed for 5 minutes, and then vulcanized to produce sheets; the first stage vulcanization temperature was 160°C, the vulcanization time was 12 minutes, and the vulcanization pressure was 12 MPa; the second stage vulcanization temperature was 200°C, the vulcanization time was 4 hours, and the performance test was shown in Table 1.

[0160] Table 1 Performance test table

[0161]

[0162] Comparison of the data in the performance test table shows that the conductive rubber prepared in Example 5 has an initial resistivity as low as 0.003 Ω·cm, and after 1000 deformation cycles in three dimensions, the maximum resistance increase is less than 15%, making it suitable for use as an excellent conductive rubber in fields such as sensors. Comparison of Example 1 and Example 6 shows that the optimal conductive network structure is achieved when the modified silver-plated aluminum powder is added at 250 parts. Comparison of Example 2, Example 3, and Example 4 shows that the optimal modified silver-plated aluminum powder is obtained at a mercaptosilane modification dosage of 1.5% and an aminosilane modification dosage of 2.5%, resulting in a conductive rubber with good bonding strength and high stability. Comparison of Comparative Example 1 and Comparative Example 2 shows that the gradient composite modified silver-plated aluminum powder significantly improves the mechanical properties and conductive stability of the conductive rubber compared to the individual modifications.

[0163] The conductive rubber prepared by the method of the present invention has a resistance change rate of ≤20% after being stretched 1000 times (50% strain); the vulcanization time is shortened by 30% to 40% compared with the traditional process, and the filler addition amount can reach 60wt% without affecting the processing fluidity.

[0164] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0165] It should be understood that the present invention is not limited to the above description and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for modifying silver-plated aluminum powder, characterized in that: The steps include: S1. Pretreatment of silver-plated aluminum powder: placing silver-plated aluminum powder with a particle size of 20-60 μm and a silver content of 15-25% in a mixed solution containing a surfactant for ultrasonic cleaning, and then drying; S2, step-by-step coupling modification: The first step is mercaptosilane modification: the silver-plated aluminum powder pretreated with S1 is reacted with a mercaptan-silane coupling agent under acidic conditions to form a primary interface layer with Ag-S bonds. After the reaction is complete, the silver-plated aluminum powder is washed with alcohol and dried to obtain mercaptosilane-modified silver-plated aluminum powder. The second step is aminosilane modification: the silver-plated aluminum powder modified with mercaptosilane is reacted with an aminosilane coupling agent under alkaline conditions to form a Si-O-Si bridged secondary interface layer. After the reaction is complete, the modified silver-plated aluminum powder is obtained after alcohol washing and drying.

2. The method for modifying silver-plated aluminum powder according to claim 1, characterized in that: The surfactant in S1 is one of sodium dodecylbenzenesulfonate, polyethylene glycol, OP-10 and polyvinylpyrrolidone K30, and the added amount of the surfactant accounts for 0.05-1% of the mass of the silver-plated aluminum powder; The mass ratio of the solvent to water in the mixed solution is (3-10):1, and the mass ratio of the silver-plated aluminum powder to the mixed solution is 1:(5-15), wherein the solvent is one of anhydrous ethanol or isopropyl alcohol.

3. The method for modifying silver-plated aluminum powder according to claim 1, characterized in that: In the ultrasonic cleaning described in S1, the ultrasonic stirring frequency is 40-80 Hz, the stirring rate is 400-800 r / min, and the stirring time is 30-60 min; The drying temperature is 60-80° C. and the drying time is 2-4 hours.

4. The method for modifying silver-plated aluminum powder according to claim 1, wherein: The specific steps of reacting the pretreated silver-plated aluminum powder with the thiol-silane coupling agent under acidic conditions in S2 are: Weigh a certain amount of mercaptosilane coupling agent, dissolve it in an ethanol aqueous solution, add an acidic pH regulator, stir to fully hydrolyze it, and then add the washed and dried silver-plated aluminum powder for coupling modification; The amount of the mercaptosilane coupling agent used accounts for 0.5%-5% of the mass of the silver-plated aluminum powder; The mercaptosilane coupling agent is one of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane and bis-[3-(triethoxysilyl)propyl]-tetrasulfide; The ethanol aqueous solution is prepared from anhydrous ethanol and water, the mass ratio of anhydrous ethanol to water is 95: (1-10), and the mass ratio of the silver-plated aluminum powder to the ethanol aqueous solution is 1: (0.8-1.5); The acidic pH regulator is one of acetic acid, hydrochloric acid and sulfuric acid, and the pH value is 3-6; The hydrolysis temperature is 25-40° C., the stirring speed is 400-800 r / min, and the stirring time is 5-10 min. The coupling modification temperature is 25-40° C., the stirring speed is 400-800 r / min, and the modification time is 30-60 min.

5. The method for modifying silver-plated aluminum powder according to claim 1, characterized in that: The specific steps of reacting the mercaptosilane-modified silver-plated aluminum powder with the aminosilane coupling agent under alkaline conditions in S2 are: Weigh a certain amount of aminosilane coupling agent, dissolve it in an ethanol aqueous solution, add an alkaline pH regulator, stir to fully hydrolyze it, and then add the silver-plated aluminum powder modified with mercaptosilane for coupling modification; The amount of the aminosilane coupling agent is 0.5-5% of the mass of the silver-plated aluminum powder; The aminosilane coupling agent is one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane and N-β-aminoethyl-γ-aminopropyltrimethoxysilane; The ethanol aqueous solution is prepared from anhydrous ethanol and water, the mass ratio of anhydrous ethanol to water is 95: (1-10), and the mass ratio of the silver-plated aluminum powder to the ethanol aqueous solution is 1: (0.8-1.5); The alkaline pH regulator is one of ammonia water, sodium hydroxide and potassium hydroxide, and the pH value is 7-9; The hydrolysis temperature is 25-40° C., the stirring speed is 400-800 r / min, and the stirring time is 5-10 min. The coupling modification temperature is 25-40° C., the stirring speed is 400-800 r / min, and the modification time is 30-60 min.

6. The method for modifying silver-plated aluminum powder according to claim 1, characterized in that: The drying temperature in S2 is 60-80° C. and the drying time is 2-4 h.

7. A method for preparing a high-stability conductive rubber, characterized in that: The modified silver-plated aluminum powder prepared by the modification method according to any one of claims 1 to 6 comprises the following steps: Step 1: Mixing: After thinning the vinyl silicone rubber at 25±2°C, add 150-300 parts by mass of modified silver-plated aluminum powder, 1-5 parts by mass of vulcanizing agent and 1-5 parts by mass of auxiliary agent in batches and mix for 10-20 minutes; Step 2: vulcanization molding to obtain high-stability conductive rubber.

8. The method for preparing a high-stability conductive rubber according to claim 7, characterized in that: The vinyl silicone rubber is Shin-Etsu Chemical KE-2005U or Dow Corning SE-6725U, the vulcanizing agent is bis(2,5-bis(2,4 ...

9. The method for preparing a high-stability conductive rubber according to claim 7, characterized in that: The vulcanization molding described in step 2 is divided into two stages. The temperature of the first stage vulcanization is 160-180℃, the vulcanization time is 8-15min, and the vulcanization pressure is 10-15MPa; The temperature of the second stage vulcanization is 180-240℃, and the vulcanization time is 3-6h.

10. A high-stability conductive rubber, characterized in that: The conductive rubber is prepared by the method for preparing a high-stability conductive rubber according to any one of claims 7 to 9, and the conductive rubber is used to prepare flexible circuits, wearable medical sensors or tactile skin of intelligent robots. The conductive rubber has a volume resistivity of ≤0.005Ω·cm, a tensile strength of ≥1.5MPa, an elongation at break of ≥200%, and a resistivity change of less than 15% under 1000 dynamic loads.

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