Self-repairing stretchable silver paste, preparation method and application thereof

Abstract

The application provides a self-repairing stretch silver paste, a preparation method and application thereof.The self-repairing stretch silver paste comprises the following raw materials: conductive silver paste, pore-forming agent and silicon modified resin; and the pore-forming agent is at least one of p-toluenesulfonyl hydrazide, sodium bicarbonate, molecular sieve and 4,4'-oxobenzene sulfonyl hydrazide.The self-repairing stretch silver paste of the application comprises the pore-forming agent and the silicon modified resin in addition to the conventional conductive silver paste, so that the silver paste can form an elastic conductor with porous cavities after gradient curing, the displacement of the conductive filler is reduced through the stress deformation of the cavities, the resistance recovery hysteresis is significantly improved, and the resistance deterioration is reduced; the obtained silver paste has fast resistance recovery speed, low hysteresis and excellent conductive stability under 50% stretch deformation, and is suitable for repeated deformation scenes such as flexible sensors, wearable devices and flexible circuits.

Description

Technical Field

[0001] This invention belongs to the field of conductive silver paste technology, and particularly relates to a self-healing stretchable silver paste, its preparation method, and its application. Background Technology

[0002] With the rapid development of flexible electronics technology, conductive silver paste has become one of the mainstream conductive materials in the field of flexible electronics due to its excellent conductivity. However, traditional conductive silver paste is prone to problems such as breakage of conductive paths, sharp increase in resistance, and poor resistance recovery ability when stretched and deformed, making it difficult to meet the needs of flexible devices that undergo repeated deformation.

[0003] Currently, improving tensile conductivity largely relies on resin modification and filler compounding, but the lack of synergistic internal structural design results in insufficient resistance recovery speed and stability. Therefore, there is a need to develop tensile silver pastes with excellent cyclic tensile stability and low recovery hysteresis to meet market demands. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a self-healing stretchable silver paste, its preparation method, and its applications. The self-healing stretchable silver paste of this invention contains a pore-forming agent and a silicone-modified resin, which allows the silver paste to form an elastic conductor with porous cavities after gradient curing. The deformation of these cavities under stress reduces the displacement of conductive fillers, significantly improving resistance recovery hysteresis and reducing resistance degradation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a self-healing stretchable silver paste, comprising the following raw materials: conductive silver paste, pore-forming agent and silicone-modified resin;

[0007] The pore-forming agent is at least one of p-toluenesulfonyl hydrazine, sodium bicarbonate, molecular sieve, and 4,4'-oxobisbenzenesulfonyl hydrazine.

[0008] Preferably, the silicone-modified resin includes at least one of silicone-modified polyurethane resin, silicone-modified acrylic resin, silicone-modified epoxy resin, silicone-modified polyester resin, silicone-modified alkyd resin, and silicone-modified phenolic resin.

[0009] Preferably, the self-healing stretching silver paste contains 1-3% by mass of pore-forming agent and 0.05-2% by mass of silicone-modified resin.

[0010] Preferably, the conductive silver paste includes conductive filler, resin, solvent, curing agent, dispersant, and thixotropic agent.

[0011] Preferably, the conductive filler includes silver-based conductive filler and carbon-based conductive filler; the silver-based conductive filler includes flake silver powder, silver nanowires, and spherical silver powder; the carbon-based conductive filler includes at least one of carbon nanotubes, graphene, graphene oxide, conductive carbon black, and graphite.

[0012] And / or, the resin includes at least one of polyurethane resin, acrylic resin, polyester resin, epoxy resin, alkyd resin, phenolic resin, and fluorocarbon resin;

[0013] And / or, the solvent includes at least one of DBE, diethylene glycol ethyl ether acetate, terpineol, terpinene, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether acetate, butyl carbitol, and butyl carbitol acetate.

[0014] And / or, the curing agent is an isocyanate curing agent;

[0015] And / or, the dispersant includes at least one of BYK-111 and BYK-2152;

[0016] And / or, the thixotropic agent includes at least one of hydrogenated castor oil, polyamide wax, polyethylene wax, and fumed silica.

[0017] Preferably, the conductive silver paste comprises the following components by weight: 15-20 parts resin, 30-40 parts flake silver powder, 20-30 parts spherical silver powder, 0.5-1 parts silver nanowires, 0.5-1 parts carbon-based conductive filler, 12-16 parts solvent, 0.25-0.4 parts curing agent, 0.01-0.02 parts dispersant, and 0.01-0.02 parts thixotropic agent.

[0018] Preferably, the conductive silver paste further includes 0.1 to 0.5 parts by weight of an alkyl glycidyl ether additive, wherein the alkyl glycidyl ether additive includes at least one of hexadecyl glycidyl ether, butyl glycidyl ether, and C12-C14 alkyl glycidyl ether.

[0019] Secondly, the present invention also provides a method for preparing the self-healing stretching silver paste, comprising the following steps:

[0020] Conductive silver paste, pore-forming agent and silicone-modified resin are mixed to obtain a mixed paste;

[0021] The mixed paste is ground and then printed onto a substrate, then cured to obtain a self-healing stretchable silver paste.

[0022] Preferably, the curing is gradient curing, which specifically includes: grinding the mixed slurry and printing it onto the substrate, first keeping it at 65~75℃ for 30~35 min, then keeping it at 85~95℃ for 30~35 min, and finally keeping it at 105~115℃ for 1~1.5 h.

[0023] Preferably, the mixed slurry is ground to a particle size ≤2.5μm.

[0024] Thirdly, the present invention also provides an application of the self-healing stretching silver paste described above or the self-healing stretching silver paste prepared by the preparation method described above in flexible circuits, wearable sensor circuits, and flexible sensors.

[0025] The self-healing stretching silver paste, its preparation method, and its application of the present invention have the following advantages compared to the prior art:

[0026] The self-healing stretching silver paste of the present invention includes, in addition to conventional conductive silver paste, a pore-forming agent and a silicone-modified resin. This allows the silver paste to form an elastic conductor with porous cavities after gradient curing. The displacement of conductive fillers is reduced by the deformation of the cavities under stress, which significantly improves the hysteresis of resistance recovery and reduces resistance deterioration. The resistance recovery speed and recovery ability are significantly improved. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the structure of the self-healing stretching silver paste of the present invention after gradient curing. Detailed Implementation

[0029] To facilitate understanding of the present invention, a more comprehensive description of the invention will be provided below in conjunction with specific embodiments. Preferred embodiments of the invention are given in the specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0030] The order in which the embodiments are described below is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". Various embodiments of the invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0031] This invention provides a self-healing stretchable silver paste, comprising the following raw materials: conductive silver paste, pore-forming agent, and silicone-modified resin;

[0032] The pore-forming agent is at least one of p-toluenesulfonyl hydrazine, sodium bicarbonate, molecular sieve, and 4,4'-oxobisbenzenesulfonyl hydrazine.

[0033] The self-healing stretchable silver paste of this invention, in addition to conventional conductive silver paste, also includes a pore-forming agent and a silicone-modified resin. This allows the silver paste to form an elastic conductor with porous cavities after gradient curing. The deformation of these cavities reduces the displacement of the conductive filler, significantly improving resistance recovery hysteresis and reducing resistance degradation. The most crucial element in the overall formulation is the addition of a suitable pore-forming agent, such as p-toluenesulfonyl hydrazine (CAS No. 1576-35-8, chemical formula C7H). 10 N2O2S), sodium bicarbonate, molecular sieve, 4,4'-oxobis(benzenesulfonyl hydrazine) (CAS No. 80-51-3, chemical formula C 12 H 14 In the film-forming stage, the viscosity of the slurry gradually increases until the solvent is basically evaporated and only the surface film layer is solidified. At this time, the temperature is not high enough to decompose the pore-forming agent. When the temperature slowly rises to the decomposition temperature, the pore-forming agent begins to slowly decompose and form cavities inside the slurry. The size of the cavity can be controlled by temperature and holding time to avoid problems such as bursting.

[0034] In some embodiments, the silicone-modified resin includes at least one of silicone-modified polyurethane resin, silicone-modified acrylic resin, silicone-modified epoxy resin, silicone-modified polyester resin, silicone-modified alkyd resin, and silicone-modified phenolic resin.

[0035] Specifically, the silicone-modified polyurethane resin can be Silok® 1039R silicone-modified polyurethane resin from Guangzhou Silok New Materials Co., Ltd. In some embodiments, the mass fraction of the pore-forming agent in the self-healing stretching silver paste is 1-3%, and the mass fraction of the silicone-modified resin is 0.05-2%.

[0036] Specifically, the mass fraction of pore-forming agent in self-healing stretching silver paste is 1-3%. Adding too little will affect the number of cavities; adding too much will easily cause bursting, reduce structural strength, and affect the overall resistivity of the silver paste, especially for systems with already high original resistivity. Adding too much will result in excessive resistivity, making it unable to carry electron transport. The mass fraction of silicon-modified resin in self-healing stretching silver paste is 0.05-2%. When the amount added is insufficient, it cannot improve the stretch recovery hysteresis, and when the amount added is too much, it will seriously deteriorate the overall electrical properties of the paste.

[0037] Further, preferably, the mass fraction of the pore-forming agent in the self-healing stretching silver paste is 1~2%, and the mass fraction of the silicone-modified resin is 0.05~1.5%; more preferably, the mass fraction of the pore-forming agent in the self-healing stretching silver paste is 1.89%, and the mass fraction of the silicone-modified resin is 1.42%. The above-mentioned amounts of silicone-modified polyurethane and pore-forming agent, without significantly affecting the deterioration of the electrical properties of the silver paste, result in a conductor with a porous structure, significantly improving the resistance recovery speed and recovery ability, and the resistance completely recovers to the initial value after stretching by 50% for two minutes.

[0038] In some embodiments, the conductive silver paste includes conductive filler, resin, solvent, curing agent, dispersant, and thixotropic agent.

[0039] In some embodiments, the conductive filler includes silver-based conductive filler and carbon-based conductive filler. The silver-based conductive filler includes flake silver powder, silver nanowires, and spherical silver powder. The carbon-based conductive filler includes at least one of carbon nanotubes, graphene, graphene oxide, conductive carbon black, and graphite.

[0040] In some embodiments, the resin includes at least one of polyurethane resin, acrylic resin, polyester resin, epoxy resin, alkyd resin, phenolic resin, and fluorocarbon resin.

[0041] In some embodiments, the solvent includes at least one of DBE (divalent esters (DBE) are a mixture of dibasic esters composed of dimethyl succinate, dimethyl glutarate and dimethyl adipate), diethylene glycol ethyl ether acetate, terpineol, terpinene, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether acetate, butyl carbitol, and butyl carbitol acetate;

[0042] In some embodiments, the curing agent may be an isocyanate curing agent.

[0043] Specifically, the polyurethane resin can be Lubrizol's polyurethane 5719, polyurethane 5703, or polyurethane 5836p.

[0044] The curing agent may be Hafotex® HF-4370 oil-based blocked curing agent, Covestro Desmodur Z4470 BAIPDI trimer curing agent, etc., purchased from Guangzhou Haoyi New Material Technology Co., Ltd. In some embodiments, the conductive silver paste comprises the following components by weight: 15-20 parts resin, 30-40 parts flake silver powder, 20-30 parts spherical silver powder, 0.5-1 part silver nanowires, 0.5-1 part carbon-based conductive filler, 12-16 parts solvent, 0.25-0.4 parts curing agent, 0.01-0.02 parts dispersant, and 0.01-0.02 parts thixotropic agent.

[0045] In some embodiments, the dispersant includes at least one of BYK-111 and BYK-2152; both BYK-111 and BYK-2152 are wetting and dispersing agents from BYK (Germany).

[0046] Thixotropic agents include at least one of hydrogenated castor oil, polyamide wax, polyethylene wax, and fumed silica.

[0047] In some embodiments, the conductive silver paste further includes 0.1 to 0.5 parts by weight of an alkyl glycidyl ether additive, wherein the alkyl glycidyl ether additive includes at least one of hexadecyl glycidyl ether, butyl glycidyl ether, and C12-C14 alkyl glycidyl ether.

[0048] In some embodiments, the silicone-modified resin needs to be selected as a system with high compatibility with the host resin, and it itself needs to have suitable strength and glass transition temperature (Tg). Additives such as alkyl glycidyl ethers can be added to reduce local agglomeration of silicon segments, allowing the silicone-modified resin to be uniformly dispersed in the slurry. Specifically, hexadecyl glycidyl ether (CAS No. 240-104-5, chemical formula C...) can be selected as the alkyl glycidyl ether additive. 19 H 38 O2), butyl glycidyl ether (CAS No. 2426-08-6, chemical formula C7H) 14 O2), C12-C14 alkyl glycidyl ether.

[0049] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned self-healing stretching silver paste, comprising the following steps:

[0050] S1. Mix conductive silver paste, pore-forming agent and silicone-modified resin to obtain a mixed paste;

[0051] S2. After grinding the mixed paste, screen print it onto the substrate and cure it to obtain a self-healing stretchable silver paste.

[0052] In some embodiments, curing is gradient curing, which specifically includes: grinding the mixed slurry and printing it onto the substrate, first holding it at 65~75℃ for 30~35 min, then holding it at 85~95℃ for 30~35 min, and finally holding it at 105~115℃ for 1~1.5 h.

[0053] Specifically, the above gradient curing process includes the following steps:

[0054] Pre-curing: The printed silver paste wet film is kept at 65~75℃ for 30~35 minutes to allow the solvent to fully evaporate and the paste surface to form a film;

[0055] Controlled foaming: Raise the temperature to 85~95℃ and keep it at that temperature for 30~35 minutes to allow the pore-forming agent to decompose gently and form a uniform porous cavity inside the silver paste;

[0056] Complete curing: Continue heating to 105~115℃ and hold for 1~1.5h to allow the resin system to fully cross-link and obtain a cured conductive film with a porous elastic structure.

[0057] This invention achieves mild and controllable foaming by controlling the amount of pore-forming agent added (1-3 wt%) and the amount of silicone-modified resin added (0.05-2 wt%), combined with gradient curing, thus avoiding pore bursting and structural strength reduction. The resulting silver paste exhibits fast resistance recovery, low hysteresis, and excellent conductivity stability under 50% tensile deformation, making it suitable for applications requiring repeated deformation, such as flexible sensors, wearable devices, and flexible circuits.

[0058] refer to Figure 1 As shown, this is a schematic diagram of the internal porous structure of the self-healing stretching silver paste of the present invention, which intuitively demonstrates the core design of the present invention:

[0059] Porous cavity structure: Numerous circular / quasi-circular pores of varying sizes and uniform distribution are formed inside the silver paste. These pores can undergo elastic deformation during stretching, absorbing stress and reducing the relative displacement of conductive fillers, thereby reducing resistance recovery hysteresis and irreversible deterioration; Conductive network skeleton: The continuous matrix between the pores is an elastic conductive network composed of polyurethane / silicone-modified polyurethane resin and conductive fillers (silver powder, silver wires, carbon nanotubes), ensuring that the conductive path is maintained during deformation; Distribution of conductive fillers: The filamentous / linear structures visible in the figure represent silver wires or carbon nanotubes, which, together with silver powder, construct a three-dimensional conductive path, improving overall conductivity and mechanical stability; This is the result of the combined action of pore-forming agent + silicone-modified resin + gradient curing process: the pore-forming agent decomposes to generate controllable bubbles, the silicone-modified resin enhances the elasticity of the matrix, and gradient curing avoids pore bursting and forms a uniform porous structure.

[0060] In some embodiments, the mixed slurry is ground on a three-roll mill, and the grinding is controlled by friction and gap on the roller surface. The number of grinding passes is 5 to 8, and the particle size of the ground mixed slurry is ≤2.5μm.

[0061] In some embodiments, the substrate is selected from one or more of flexible polymer films, elastic substrates, and printed circuit board substrates, specifically including: PET (polyethylene terephthalate) film, PI (polyimide) film, TPU (thermoplastic polyurethane) film, PDMS (polydimethylsiloxane), PU (polyurethane) film, flexible fiberglass cloth, flexible ceramic substrate, etc.

[0062] The following specific embodiments further illustrate the self-healing stretching silver paste and its preparation method of the present invention. This section further illustrates the content of the present invention in conjunction with specific embodiments, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0063] Example 1

[0064] This embodiment provides a self-healing stretchable silver paste, comprising the following raw materials in parts by weight:

[0065] 15 parts polyurethane resin, 40 parts flake silver powder with an average length of 1 μm and an average thickness of 100 nm, 30 parts spherical silver powder with an average particle size of 2 μm, 0.9 parts silver nanowires with a length of 15 μm and a diameter of 0.3 μm, 0.8 parts single-walled carbon nanotubes, 15 parts solvent, 0.3 parts curing agent, 0.01 parts dispersant, 0.01 parts thixotropic agent, 2 parts pore-forming agent (mass fraction 1.89%), 1.5 parts silicone-modified resin (mass fraction 1.42%), and 0.2 parts cetyl glycidyl ether;

[0066] The polyurethane resin is Lubrizol's Polyurethane 5719 from the United States; the curing agent is an isocyanate curing agent, specifically Hafotex® HF-4370 oil-based blocked curing agent, purchased from Guangzhou Haoyi New Material Technology Co., Ltd.

[0067] The solvent is diethylene glycol ethyl ether acetate;

[0068] The dispersant is BYK-111;

[0069] The thixotropic agent is fumed silica (i.e., fumed white carbon black, specifically Evonik AEROSIL® 200 hydrophilic fumed silica).

[0070] The pore-forming agent is p-toluenesulfonyl hydrazine;

[0071] The silicone-modified resin is Silok® 1039R silicone-modified polyurethane resin from Guangzhou Silok New Materials Co., Ltd.

[0072] This embodiment also provides a method for preparing the above-mentioned self-healing stretching silver paste, including the following steps:

[0073] S1. Mix the above polyurethane resin, flake silver powder, spherical silver powder, silver nanowires, single-walled carbon nanotubes, solvent, curing agent, dispersant, thixotropic agent, pore-forming agent, silicone-modified resin, and cetyl glycidyl ether to obtain a mixed slurry.

[0074] S2. Grind the mixed slurry to make the particle size ≤2.5μm;

[0075] S3. The ground mixed paste is screen-printed onto a substrate (specifically a PET film) and then cured in a gradient to obtain a self-healing stretchable silver paste.

[0076] The gradient curing process specifically includes: grinding the mixed slurry and printing it onto the substrate, first keeping it at 70°C for 30 minutes, then at 90°C for 30 minutes, and finally at 110°C for 1 hour.

[0077] Example 2

[0078] The self-healing stretching silver paste provided in this embodiment is the same as that in Embodiment 1, except that the weight of the silicone-modified polyurethane resin is 2 parts (mass fraction of 1.88%), and the rest is the same as in Embodiment 1, with the pore-forming agent having a mass fraction of 1.88%.

[0079] Example 3

[0080] The self-healing stretching silver paste provided in this embodiment is the same as that in Embodiment 1, except that the weight of the pore-forming agent is 3 parts (mass fraction 2.81%), while the rest is the same as in Embodiment 1, and the mass fraction of the silicone-modified resin is 1.41%.

[0081] Comparative Example 1

[0082] The self-healing stretching silver paste provided in this comparative example is the same as that in Example 1, except that 1.5 parts of silicone-modified polyurethane resin are replaced with 1.5 parts of conventional polyurethane (specifically, Lubrizol's polyurethane 5719). All other parts are the same as in Example 1.

[0083] Comparative Example 2

[0084] The self-healing stretching silver paste provided in this comparative example is the same as that in Example 1, except that it does not contain a pore-forming agent, while all other aspects are the same as those in Example 1.

[0085] Comparative Example 3

[0086] The self-healing stretching silver paste provided in this comparative example is the same as that in Example 1, except that it does not contain a pore-forming agent, and 1.5 parts of silicone-modified polyurethane resin are replaced with 1.5 parts of conventional polyurethane (specifically, Lubrizol's polyurethane 5719). All other aspects are the same as in Example 1.

[0087] Performance testing

[0088] The self-healing stretching silver pastes obtained in Examples 1-3 and Comparative Examples 1-3 were stretched by 50% (i.e., the sample was stretched to 1.5 times its original length). After the external force was removed, the resistance values ​​were measured at 0 min, 1 min, 2 min, 5 min, 10 min, 1 h, 5 h, and 24 h. The recovery hysteresis was evaluated by comparing the change rate before and after. The results are shown in Table 1 below.

[0089] Table 1 - Resistance of self-healing stretchable silver paste before and after stretching in different embodiments and comparative examples

[0090]

[0091] As can be seen from Table 1, in Example 1, by adding silicon-modified polyurethane and a pore-forming agent, a conductor with a porous structure was obtained without significantly affecting or deteriorating the electrical properties of the silver paste. The resistance recovery speed and recovery ability were significantly improved, and the resistance completely recovered to the initial value after being stretched by 50% for two minutes.

[0092] In Example 2, by increasing the amount of silicone-modified polyurethane to 2 parts, the resistance of the silver paste was significantly worsened, and the resistance recovery hysteresis was quite severe, only reaching the initial value 1 hour after stretching.

[0093] In Example 3, increasing the pore-forming agent content reduced the tensile strength to some extent, while the hysteresis of electrical resistance recovery remained acceptable. However, after stretching, some connection points may suffer permanent damage, leading to an 8% deterioration in irreversible resistance.

[0094] In Comparative Example 1, only a pore-forming agent was added. After stretching, the length recovery was slow and there was a permanent deformation zone. The resistance recovery was severely delayed, and the irreversible resistance deteriorated by 37.5%.

[0095] In Comparative Example 2, only silicon-modified resin was added, without the participation of pore-forming agents, resulting in no porous structure and a large hysteresis in resistance recovery.

[0096] Comparative Example 3 uses a conventional stretching silver paste solution, which has no porous structure, has a large hysteresis in resistance recovery, and exhibits irreversible deterioration of 50%.

[0097] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A self-healing stretchable silver paste, characterized in that, The raw materials include: conductive silver paste, pore-forming agent, and silicone-modified resin; The pore-forming agent is at least one of p-toluenesulfonyl hydrazine, sodium bicarbonate, molecular sieve, and 4,4'-oxobisbenzenesulfonyl hydrazine.

2. The self-healing stretching silver paste as described in claim 1, characterized in that, The silicon-modified resin includes at least one of silicon-modified polyurethane resin, silicon-modified acrylic resin, silicon-modified epoxy resin, silicon-modified polyester resin, silicon-modified alkyd resin, and silicon-modified phenolic resin.

3. The self-healing stretching silver paste as described in claim 1, characterized in that, The self-healing stretching silver paste contains 1-3% pore-forming agent and 0.05-2% silicone-modified resin by mass.

4. The self-healing stretching silver paste as described in claim 1, characterized in that, The conductive silver paste includes conductive fillers, resin, solvent, curing agent, dispersant, and thixotropic agent.

5. The self-healing stretching silver paste as described in claim 4, characterized in that, The conductive filler includes silver-based conductive filler and carbon-based conductive filler. The silver-based conductive filler includes flake silver powder, silver nanowires, and spherical silver powder. The carbon-based conductive filler includes at least one of carbon nanotubes, graphene, graphene oxide, conductive carbon black, and graphite. And / or, the resin includes at least one of polyurethane resin, acrylic resin, polyester resin, epoxy resin, alkyd resin, phenolic resin, and fluorocarbon resin; And / or, the solvent includes at least one of DBE, diethylene glycol ethyl ether acetate, terpineol, terpinene, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether acetate, butyl carbitol, and butyl carbitol acetate. And / or, the curing agent is an isocyanate curing agent; And / or, the dispersant includes at least one of BYK-111 and BYK-2152; And / or, the thixotropic agent includes at least one of hydrogenated castor oil, polyamide wax, polyethylene wax, and fumed silica.

6. The self-healing stretching silver paste as described in claim 5, characterized in that, The conductive silver paste comprises the following components by weight: 15-20 parts resin, 30-40 parts flake silver powder, 20-30 parts spherical silver powder, 0.5-1 parts silver nanowires, 0.5-1 parts carbon-based conductive filler, 12-16 parts solvent, 0.25-0.4 parts curing agent, 0.01-0.02 parts dispersant, and 0.01-0.02 parts thixotropic agent.

7. The self-healing stretching silver paste as described in claim 5, characterized in that, The conductive silver paste further includes 0.1 to 0.5 parts by weight of alkyl glycidyl ether additives, wherein the alkyl glycidyl ether additives include at least one of hexadecyl glycidyl ether, butyl glycidyl ether, and C12-C14 alkyl glycidyl ether.

8. A method for preparing a self-healing stretching silver paste as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Conductive silver paste, pore-forming agent and silicone-modified resin are mixed to obtain a mixed paste; The mixed paste is ground and then printed onto a substrate, then cured to obtain a self-healing stretchable silver paste.

9. The method for preparing the self-healing stretching silver paste as described in claim 8, characterized in that, The curing is gradient curing, which specifically includes: grinding the mixed slurry and printing it onto the substrate, first keeping it at 65~75℃ for 30~35min, then keeping it at 85~95℃ for 30~35min, and finally keeping it at 105~115℃ for 1~1.5h.

10. The application of a self-healing stretchable silver paste as described in any one of claims 1 to 7 or a self-healing stretchable silver paste prepared by the preparation method described in any one of claims 8 to 9 in flexible circuits, wearable sensor circuits, and flexible sensors.

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