Low resistance polymer-based conductive silver paste composition and method of making same

Abstract

The application relates to the technical field of conductive silver paste, and discloses a low-resistance polymer conductive silver paste composition and a preparation method thereof, which comprises the following raw materials in parts by mass: polymer resin 40-50 parts, nano silver powder 10-15 parts, composite silver nanowire 3-5 parts, composite layered material 5-8 parts, aromatic polyisocyanate 3-5 parts, butyl citrate 2-4 parts and ethylene glycol 6-10 parts. The contact area of the composite silver nanowire and the silver paste composition substrate is large, so that the modified silver nanowire is uniformly dispersed in the silver paste composition, the conductive performance is improved, and the system stability is improved; the composite layered material has high barrier performance to oxygen and water molecules, further inhibits the oxidation of the silver paste composition, and improves the conductive performance and the system stability of the silver paste composition.

Description

Technical Field

[0001] This invention relates to the field of conductive silver paste technology, specifically to a low-resistance polymer-type conductive silver paste composition and its preparation method. Background Technology

[0002] Polymer-based conductive silver paste composition is a functional composite material composed of silver powder (nano / micron level) as conductive filler, polymer resin as binder, and added dispersants, solvents and other functional additives. It can be cured into a film on the surface of substrates (such as plastics, ceramics, glass or flexible films) to form a highly conductive and strongly adherent conductive coating, which is widely used in electronics, photovoltaics, printed circuits and other fields.

[0003] Conductive silver paste, as an electronic material, is increasingly widely used in the field of conductivity. To improve the conductivity of existing conductive silver pastes, silver nanowires are used to partially replace silver powder. This can form a network structure in the silver paste composition that can absorb and weaken external stress, improving the mechanical strength of the polymer-based silver paste composition after curing. However, silver nanowires are prone to agglomeration, leading to poor interfacial properties between organic and inorganic raw materials, resulting in poor conductivity of the product. Furthermore, silver nanowires can form oxides upon contact with oxygen and water molecules, further reducing the conductivity of the silver paste composition.

[0004] Based on the above statements, the present invention provides a low-resistance polymer-type conductive silver paste composition and its preparation method. Summary of the Invention

[0005] This invention provides a low-resistance polymer-type conductive silver paste composition, which solves the problem of poor interfacial properties between organic and inorganic raw materials in conductive silver paste.

[0006] The technical solution of the present invention:

[0007] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight: 40-50 parts polymer resin, 10-15 parts nano silver powder, 3-5 parts composite silver nanowires, 5-8 parts composite layered material, 3-5 parts aromatic polyisocyanate, 2-4 parts butyl citrate, and 6-10 parts ethylene glycol.

[0008] Among them, the composite silver nanowires are obtained by in-situ synthesis of nano-copper on the surface of tannic acid-modified silver nanowires, followed by mixing and reaction with rice husk powder.

[0009] The composite layered material is obtained by intercalating sheet-like alumina with graphene oxide nanosheets;

[0010] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0011] Nano-silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1000-1500 r / min for 5-10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 500-800 r / min for 15-20 min to obtain a conductive silver paste composition.

[0012] Furthermore, the polymer resin is a hydroxyl acrylic resin with a hydroxyl value of 80-100 mg KOH / g.

[0013] Furthermore, the aromatic polyisocyanate is selected from toluene diisocyanate and / or diphenylmethane diisocyanate.

[0014] Furthermore, the composite silver nanowires are specifically prepared by the following steps:

[0015] A1. Add tannic acid to ethanol and stir until completely dissolved. Add silver nanowires, stir evenly, centrifuge to collect the precipitate, wash the precipitate, and dry it to obtain tannic acid modified silver nanowires.

[0016] A2. Add copper chloride to deionized water and stir until homogeneous. Add tannic acid-modified silver nanowires and stir. Add glucose and stir until the reaction is complete. Cool to room temperature, filter, wash and dry to obtain silver nanowires loaded with copper nanowires.

[0017] A3. Add silver nanowires loaded with copper nanoparticles, rice husk powder, and citric acid to ethanol, stir until homogeneous, add hydrochloric acid, stir until the reaction is complete, filter, wash, dry, place in a tube furnace, add potassium hydroxide solution, purge with nitrogen gas, carbonize at 700-750℃ for 4-5 hours, cool to room temperature, remove, wash, and dry to obtain composite silver nanowires.

[0018] Furthermore, during the A1 reaction process described above, tannic acid contains a large number of phenolic hydroxyl structures, which have good adhesion properties, allowing tannic acid to adhere to the surface of silver nanowires, thus giving the silver nanowires excellent adhesion and obtaining tannic acid-modified silver nanowires.

[0019] Furthermore, in the A2 reaction process described above, the tannic acid-modified silver nanowires can combine with copper ions in the copper chloride solution, so that the copper ions are uniformly dispersed on the surface of the silver nanowires. Glucose acts as a reducing agent to achieve in-situ synthesis of nano-copper on the surface of the silver nanowires, forming core-shell structured nanowires, and thus obtaining silver nanowires loaded with nano-copper.

[0020] Furthermore, in the A3 reaction process described above, rice husk powder is dissolved in ethanol, where the hydroxyl groups can react with the carboxyl groups of citric acid. The carboxyl groups of citric acid can also react with the hydroxyl groups of the copper nanowires on the surface of the copper nanowires, allowing the rice husk powder to adhere to the surface of the copper nanowires through citric acid. After high-temperature carbonization, the rice husk powder decomposes to form a dense carbon layer. Potassium hydroxide solution acts as an activator, forming channels on the surface of the dense carbon layer, thus achieving the synthesis of a porous carbon structure on the surface of the copper nanowires, resulting in modified silver nanowires.

[0021] Furthermore, in step A1, the ratio of tannic acid, ethanol, and silver nanowires is (1-1.2)g:(55-65)mL:(4.5-4.7)g.

[0022] Further, in step A2, the ratio of copper chloride, deionized water, tannic acid-modified silver nanowires, and glucose is (1-3)g:(45-55)mL:(5.2-5.4)g:(1-1.2)g.

[0023] Furthermore, in step A3, the ratio of the amounts of silver nanowires loaded with copper nanoparticles, rice husk powder, citric acid, ethanol, hydrochloric acid, and potassium hydroxide solution is (5.5-5.7)g:(2.2-2.4)g:(0.4-0.6)g:(55-65)mL:(0.1-0.3)mL:(4-5)mL.

[0024] Furthermore, the composite layered material is specifically prepared by the following steps:

[0025] After cleaning the graphene oxide nanosheets with hydrochloric acid, they were washed with deionized water until the pH of the washing solution was neutral. The nanosheets were then added to the deionized water and stirred evenly. Flake alumina was added and ultrasonically treated at 40-60 kHz for 20-30 min. After filtration, washing, and drying, the wear-resistant filler was obtained.

[0026] Furthermore, the above reaction process, when ultrasonically treated at 40-60KHz, can weaken the interlayer forces of graphene oxide nanosheets and increase the interlayer spacing of graphene oxide nanosheets, allowing sheet-like alumina to be intercalated into graphene oxide nanosheets to form a composite layered material.

[0027] Furthermore, the ratio of graphene oxide nanosheets, deionized water, and sheet alumina is (1.4-1.6) g: (90-110) mL: (0.8-1) g.

[0028] Furthermore, the graphene oxide nanosheets have a thickness of 50-80 nm and a sheet diameter of 8-10 μm.

[0029] Furthermore, the thickness of the sheet-like alumina is 100-150 nm, and the sheet diameter is 5-8 μm.

[0030] The present invention has the following beneficial effects:

[0031] (1) In the technical solution of the present invention, tannic acid is used to modify silver nanowires, so that silver nanowires have excellent complexation and adsorption properties for copper ions, which is conducive to the in-situ synthesis of nano-copper on the surface of silver nanowires, forming a core-shell structure, improving the conductivity and mechanical properties of the silver paste composition. Moreover, tannic acid-modified silver nanowires serve as a carrier for nano-copper, avoiding the direct addition of nano-copper to the silver paste composition, which is prone to agglomeration, resulting in poor system stability of the silver paste composition, and inability to conduct conductive series, thus resulting in poor conductivity of the product.

[0032] (2) In the technical solution of the present invention, nano-copper is synthesized in situ on the surface of silver nanowires to form core-shell structured nanowires. On the one hand, by synthesizing nano-copper in situ on the surface of silver nanowires, the nano-copper is uniformly dispersed on the surface of silver nanowires, avoiding the nano-copper from falling off and migrating into the silver paste composition, agglomerating in the silver paste composition, and affecting the conductivity of the silver paste composition. Moreover, the synthesized nano-copper has excellent conductivity, thereby enhancing the conductivity of the silver paste composition. On the other hand, silver nanowires are selected to partially replace silver powder and form a core-shell structure of nano-copper coating silver nanowires, which has an excellent aspect ratio. It can form a network structure in the silver paste composition that can absorb and weaken external stress, improve the mechanical strength of the polymer-type silver paste composition after curing, and avoid poor mechanical properties after curing, which can easily break at high temperature and affect conductivity.

[0033] (3) In the technical solution of the present invention, a porous carbon structure is synthesized on the surface of silver nanowires loaded with copper nanowires to obtain modified silver nanowires. On the one hand, the porous carbon synthesized on the surface of silver nanowires loaded with copper nanowires has excellent corrosion resistance and can prevent oxygen and water molecules from penetrating and contacting the silver nanowires loaded with copper nanowires, thus avoiding the formation of oxides by the silver nanowires loaded with copper nanowires in contact with oxygen in the air, which would reduce the conductivity of the silver paste composition. Moreover, as a carbon material, porous carbon also has excellent conductivity. When combined with silver nanowires loaded with copper nanowires, a conductive network is formed in the silver paste composition, which improves the conductivity of the silver paste composition. On the other hand, porous carbon increases the surface roughness of the silver nanowires loaded with copper nanowires, increases the contact area with the substrate of the silver paste composition, and makes the modified silver nanowires uniformly dispersed in the silver paste composition, thereby improving the conductivity and system stability.

[0034] (4) In the technical solution of the present invention, the composite layered material formed by intercalating sheet alumina with graphene oxide nanosheets can absorb and weaken the energy generated by external stress, prevent the expansion of cracks after the silver paste composition is cured, and improve the mechanical properties of the silver paste composition. Moreover, the composite layered material has high barrier properties to oxygen and water molecules, further inhibiting the oxidation of the silver paste composition and improving the conductivity and system stability of the silver paste composition. In addition, the intercalating sheet alumina with graphene oxide nanosheets avoids the stacking and agglomeration of graphene oxide nanosheets, which would result in poor system stability and reduced conductivity. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] The raw materials used in the embodiments of this invention are shown below, and all reagents used are analytical grade.

[0037] The polymer resin is a hydroxyl acrylic resin with a hydroxyl value of 90 mg KOH / g.

[0038] The aromatic polyisocyanate is toluene diisocyanate.

[0039] The graphene oxide nanosheets are 60 nm thick and 10 μm in diameter.

[0040] The thickness of the sheet-like alumina is 100 nm, and the sheet diameter is 8 μm.

[0041] Example 1

[0042] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight:

[0043] 40 parts polymer resin, 10 parts nano silver powder, 3 parts composite silver nanowires, 5 parts composite layered material, 3 parts aromatic polyisocyanate, 2 parts butyl citrate, and 6 parts ethylene glycol.

[0044] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0045] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1000 r / min for 5 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 500 r / min for 15 min to obtain a conductive silver paste composition.

[0046] The composite silver nanowires are prepared by the following steps:

[0047] A1. Add 1g of tannic acid to 55mL of ethanol and stir at 40℃ until completely dissolved. Add 4.5g of silver nanowires and stir at 600r / min for 2h. Centrifuge at 3000r / min to collect the precipitate. Wash the precipitate three times with deionized water and dry it in an oven at 70℃ for 10min to obtain tannic acid-modified silver nanowires.

[0048] A2. Add 1g of copper chloride to 45mL of deionized water, stir well, add 5.2g of tannic acid-modified silver nanowires, stir for 25min, add 1g of glucose, stir and react at 70℃ for 30min, cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 60℃ for 10min to obtain silver nanowires loaded with copper nanowires.

[0049] A3. Add 5.5g of silver nanowires loaded with copper nanoparticles, 2.2g of rice husk powder, and 0.4g of citric acid to 55mL of ethanol, stir well, add 0.1mL of 36% hydrochloric acid, stir and react at 70℃ for 30min, filter, wash three times with deionized water, dry in a 60℃ oven for 10min, place in a tube furnace, add 4mL of 30% potassium hydroxide solution, purge with nitrogen, carbonize at 700℃ for 4h, cool to room temperature, remove, wash three times with deionized water, and dry in a 60℃ oven for 10min to obtain composite silver nanowires.

[0050] The composite layered material is prepared by the following steps:

[0051] 1.4g of graphene oxide nanosheets were washed with 36% hydrochloric acid, then washed with deionized water until the pH of the washing solution was neutral. The solution was then added to 90mL of deionized water and stirred evenly. 0.8g of sheet alumina was added, and the mixture was ultrasonically treated at 40KHz for 20min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 80℃ for 10min to obtain the wear-resistant filler.

[0052] Example 2

[0053] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight:

[0054] 45 parts polymer resin, 13 parts nano silver powder, 4 parts composite silver nanowires, 6 parts composite layered material, 4 parts aromatic polyisocyanate, 3 parts butyl citrate, and 8 parts ethylene glycol.

[0055] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0056] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1300 r / min for 8 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 650 r / min for 18 min to obtain a conductive silver paste composition.

[0057] The composite silver nanowires are prepared by the following steps:

[0058] A1. Add 1.1 g of tannic acid to 60 mL of ethanol and stir at 40 °C until completely dissolved. Add 4.6 g of silver nanowires and stir at 600 r / min for 2 h. Centrifuge at 3000 r / min to collect the precipitate. Wash the precipitate three times with deionized water and dry it in an oven at 70 °C for 10 min to obtain tannic acid-modified silver nanowires.

[0059] A2. Add 2g of copper chloride to 50mL of deionized water and stir well. Add 5.3g of tannic acid-modified silver nanowires and stir for 25min. Add 1.1g of glucose and stir at 70℃ for 30min. Cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 60℃ for 10min to obtain silver nanowires loaded with copper nanowires.

[0060] A3. Add 5.6g of silver nanowires loaded with copper nanoparticles, 2.3g of rice husk powder, and 0.5g of citric acid to 60mL of ethanol, stir well, add 0.2mL of 36% hydrochloric acid, stir and react at 70℃ for 30min, filter, wash three times with deionized water, dry in a 60℃ oven for 10min, place in a tube furnace, add 4.5mL of 30% potassium hydroxide solution, purge with nitrogen, carbonize at 700-750℃ for 4-5h, cool to room temperature, remove, wash three times with deionized water, and dry in a 60℃ oven for 10min to obtain composite silver nanowires.

[0061] The composite layered material is prepared by the following steps:

[0062] 1.5g of graphene oxide nanosheets were washed with 36% hydrochloric acid, then washed with deionized water until the pH of the washing solution was neutral. The solution was then added to 100mL of deionized water and stirred evenly. 0.9g of sheet alumina was added, and the mixture was ultrasonically treated at 50KHz for 25min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 80℃ for 10min to obtain the wear-resistant filler.

[0063] Example 3

[0064] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight:

[0065] 50 parts polymer resin, 15 parts nano silver powder, 5 parts composite silver nanowires, 8 parts composite layered material, 5 parts aromatic polyisocyanate, 4 parts butyl citrate, and 10 parts ethylene glycol.

[0066] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0067] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1500 r / min for 10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 800 r / min for 20 min to obtain a conductive silver paste composition.

[0068] The composite silver nanowires are prepared by the following steps:

[0069] A1. Add 1.2g of tannic acid to 65mL of ethanol and stir at 40℃ until completely dissolved. Add 4.7g of silver nanowires and stir at 600r / min for 2h. Centrifuge at 3000r / min to collect the precipitate. Wash the precipitate three times with deionized water and dry it in an oven at 70℃ for 10min to obtain tannic acid-modified silver nanowires.

[0070] A2. Add 3g of copper chloride to 55mL of deionized water and stir well. Add 5.4g of tannic acid-modified silver nanowires and stir for 25min. Add 1.2g of glucose and stir at 70℃ for 30min. Cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 60℃ for 10min to obtain silver nanowires loaded with copper nanowires.

[0071] A3. 5.7 g of silver nanowires loaded with copper nanoparticles, 2.4 g of rice husk powder, and 0.6 g of citric acid were added to 65 mL of ethanol and stirred until homogeneous. 0.3 mL of 36% hydrochloric acid was added, and the mixture was stirred at 70 °C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in a 60 °C oven for 10 min. The mixture was then placed in a tube furnace, and 5 mL of 30% potassium hydroxide solution was added. Nitrogen gas was introduced, and the mixture was carbonized at 750 °C for 5 h. After cooling to room temperature, the mixture was removed, washed three times with deionized water, and dried in a 60 °C oven for 10 min to obtain composite silver nanowires.

[0072] The composite layered material is prepared by the following steps:

[0073] 1.6g of graphene oxide nanosheets were washed with 36% hydrochloric acid, then washed with deionized water until the pH of the washing solution was neutral. The solution was then added to 110mL of deionized water and stirred evenly. 1g of sheet alumina was added, and the mixture was ultrasonically treated at 60KHz for 30min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 80℃ for 10min to obtain the wear-resistant filler.

[0074] Comparative Example 1

[0075] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight:

[0076] 50 parts polymer resin, 15 parts nano silver powder, 5 parts composite silver nanowires, 8 parts composite layered material, 5 parts aromatic polyisocyanate, 4 parts butyl citrate, and 10 parts ethylene glycol.

[0077] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0078] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1500 r / min for 10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 800 r / min for 20 min to obtain a conductive silver paste composition.

[0079] The composite silver nanowires are prepared by the following steps:

[0080] A1. Add 3g of copper chloride to 55mL of deionized water and stir well. Add 5.4g of silver nanowires and stir for 25min. Add 1.2g of glucose and stir at 70℃ for 30min. Cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 60℃ for 10min to obtain silver nanowires loaded with copper nanowires.

[0081] A2. 5.7 g of silver nanowires loaded with copper nanoparticles, 2.4 g of rice husk powder, and 0.6 g of citric acid were added to 65 mL of ethanol and stirred until homogeneous. 0.3 mL of 36% hydrochloric acid was added, and the mixture was stirred at 70 °C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in a 60 °C oven for 10 min. The mixture was then placed in a tube furnace, and 5 mL of 30% potassium hydroxide solution was added. Nitrogen gas was introduced, and the mixture was carbonized at 750 °C for 5 h. After cooling to room temperature, the mixture was removed, washed three times with deionized water, and dried in a 60 °C oven for 10 min to obtain composite silver nanowires.

[0082] The composite layered material is prepared by the following steps:

[0083] 1.6g of graphene oxide nanosheets were washed with 36% hydrochloric acid, then washed with deionized water until the pH of the washing solution was neutral. The solution was then added to 110mL of deionized water and stirred evenly. 1g of sheet alumina was added, and the mixture was ultrasonically treated at 60KHz for 30min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 80℃ for 10min to obtain the wear-resistant filler.

[0084] Comparative Example 2

[0085] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight:

[0086] 50 parts polymer resin, 15 parts nano silver powder, 5 parts composite silver nanowires, 8 parts composite layered material, 5 parts aromatic polyisocyanate, 4 parts butyl citrate, and 10 parts ethylene glycol.

[0087] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0088] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1500 r / min for 10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 800 r / min for 20 min to obtain a conductive silver paste composition.

[0089] The composite silver nanowires are prepared by the following steps:

[0090] A1. Add 1.2g of tannic acid to 65mL of ethanol and stir at 40℃ until completely dissolved. Add 4.7g of silver nanowires and stir at 600r / min for 2h. Centrifuge at 3000r / min to collect the precipitate. Wash the precipitate three times with deionized water and dry it in an oven at 70℃ for 10min to obtain tannic acid-modified silver nanowires.

[0091] A2. 5.7 g of tannic acid-modified silver nanowires, 2.4 g of rice husk powder, and 0.6 g of citric acid were added to 65 mL of ethanol and stirred until homogeneous. 0.3 mL of 36% hydrochloric acid was added, and the mixture was stirred at 70 °C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in a 60 °C oven for 10 min. The mixture was then placed in a tube furnace, and 5 mL of 30% potassium hydroxide solution was added. Nitrogen gas was introduced, and the mixture was carbonized at 750 °C for 5 h. After cooling to room temperature, the mixture was removed, washed three times with deionized water, and dried in a 60 °C oven for 10 min to obtain composite silver nanowires.

[0092] The composite layered material is prepared by the following steps:

[0093] 1.6g of graphene oxide nanosheets were washed with 36% hydrochloric acid, then washed with deionized water until the pH of the washing solution was neutral. The solution was then added to 110mL of deionized water and stirred evenly. 1g of sheet alumina was added, and the mixture was ultrasonically treated at 60KHz for 30min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 80℃ for 10min to obtain the wear-resistant filler.

[0094] Comparative Example 3

[0095] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight:

[0096] 50 parts polymer resin, 15 parts nano silver powder, 5 parts silver nanowires loaded with nano copper, 8 parts composite layered material, 5 parts aromatic polyisocyanate, 4 parts butyl citrate, and 10 parts ethylene glycol.

[0097] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0098] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1500 r / min for 10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 800 r / min for 20 min to obtain a conductive silver paste composition.

[0099] Silver nanowires loaded with copper nanoparticles are prepared by the following steps:

[0100] A1. Add 1.2g of tannic acid to 65mL of ethanol and stir at 40℃ until completely dissolved. Add 4.7g of silver nanowires and stir at 600r / min for 2h. Centrifuge at 3000r / min to collect the precipitate. Wash the precipitate three times with deionized water and dry it in an oven at 70℃ for 10min to obtain tannic acid-modified silver nanowires.

[0101] A2. Add 3g of copper chloride to 55mL of deionized water and stir well. Add 5.4g of tannic acid-modified silver nanowires and stir for 25min. Add 1.2g of glucose and stir at 70℃ for 30min. Cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 60℃ for 10min to obtain silver nanowires loaded with copper nanowires.

[0102] The composite layered material is prepared by the following steps:

[0103] 1.6g of graphene oxide nanosheets were washed with 36% hydrochloric acid, then washed with deionized water until the pH of the washing solution was neutral. The solution was then added to 110mL of deionized water and stirred evenly. 1g of sheet alumina was added, and the mixture was ultrasonically treated at 60KHz for 30min. After filtration, the mixture was washed three times with deionized water and dried in an oven at 80℃ for 10min to obtain the wear-resistant filler.

[0104] Comparative Example 4

[0105] A low-resistance polymer-type conductive silver paste composition comprising the following raw materials in parts by weight:

[0106] 50 parts polymer resin, 15 parts nano silver powder, 5 parts composite silver nanowires, 8 parts graphene oxide nanosheets, 5 parts aromatic polyisocyanate, 4 parts butyl citrate, and 10 parts ethylene glycol.

[0107] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0108] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1500 r / min for 10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 800 r / min for 20 min to obtain a conductive silver paste composition.

[0109] The composite silver nanowires are prepared by the following steps:

[0110] A1. Add 1.2g of tannic acid to 65mL of ethanol and stir at 40℃ until completely dissolved. Add 4.7g of silver nanowires and stir at 600r / min for 2h. Centrifuge at 3000r / min to collect the precipitate. Wash the precipitate three times with deionized water and dry it in an oven at 70℃ for 10min to obtain tannic acid-modified silver nanowires.

[0111] A2. Add 3g of copper chloride to 55mL of deionized water and stir well. Add 5.4g of tannic acid-modified silver nanowires and stir for 25min. Add 1.2g of glucose and stir at 70℃ for 30min. Cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 60℃ for 10min to obtain silver nanowires loaded with copper nanowires.

[0112] A3. 5.7 g of silver nanowires loaded with copper nanoparticles, 2.4 g of rice husk powder, and 0.6 g of citric acid were added to 65 mL of ethanol and stirred until homogeneous. 0.3 mL of 36% hydrochloric acid was added, and the mixture was stirred at 70 °C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in a 60 °C oven for 10 min. The mixture was then placed in a tube furnace, and 5 mL of 30% potassium hydroxide solution was added. Nitrogen gas was introduced, and the mixture was carbonized at 750 °C for 5 h. After cooling to room temperature, the mixture was removed, washed three times with deionized water, and dried in a 60 °C oven for 10 min to obtain composite silver nanowires.

[0113] Comparative Example 5

[0114] A low-resistance polymer-type conductive silver paste composition comprises the following raw materials in parts by weight: 50 parts polymer resin, 15 parts nano silver powder, 5 parts composite silver nanowires, 8 parts sheet alumina, 5 parts aromatic polyisocyanate, 4 parts butyl citrate, and 10 parts ethylene glycol.

[0115] A method for preparing a low-resistance polymer-based conductive silver paste composition includes the following preparation steps:

[0116] Nano silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1500 r / min for 10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 800 r / min for 20 min to obtain a conductive silver paste composition.

[0117] The composite silver nanowires are prepared by the following steps:

[0118] A1. Add 1.2g of tannic acid to 65mL of ethanol and stir at 40℃ until completely dissolved. Add 4.7g of silver nanowires and stir at 600r / min for 2h. Centrifuge at 3000r / min to collect the precipitate. Wash the precipitate three times with deionized water and dry it in an oven at 70℃ for 10min to obtain tannic acid-modified silver nanowires.

[0119] A2. Add 3g of copper chloride to 55mL of deionized water and stir well. Add 5.4g of tannic acid-modified silver nanowires and stir for 25min. Add 1.2g of glucose and stir at 70℃ for 30min. Cool to room temperature, filter, wash 3 times with deionized water, and dry in an oven at 60℃ for 10min to obtain silver nanowires loaded with copper nanowires.

[0120] A3. 5.7 g of silver nanowires loaded with copper nanoparticles, 2.4 g of rice husk powder, and 0.6 g of citric acid were added to 65 mL of ethanol and stirred until homogeneous. 0.3 mL of 36% hydrochloric acid was added, and the mixture was stirred at 70 °C for 30 min. After filtration, the mixture was washed three times with deionized water and dried in a 60 °C oven for 10 min. The mixture was then placed in a tube furnace, and 5 mL of 30% potassium hydroxide solution was added. Nitrogen gas was introduced, and the mixture was carbonized at 750 °C for 5 h. After cooling to room temperature, the mixture was removed, washed three times with deionized water, and dried in a 60 °C oven for 10 min to obtain composite silver nanowires.

[0121] The performance of the conductive silver paste compositions prepared in Examples 1-3 and Comparative Examples 1-5 was then tested.

[0122] The substrate (polyester film) was ultrasonically cleaned with ethanol for 10 minutes, dried, and then coated with the conductive silver paste composition prepared above. It was then cured at 100°C for 100 minutes in an electric thermostatic drying oven. Resistivity and stability tests were then performed, and the specific test methods are as follows.

[0123] Resistivity test: A four-probe resistance meter was used to measure the sheet resistance of the cured silver paste electrode. Each sample was tested 5 times and the average value was recorded.

[0124] Stability test: Place the sample in an environment of 60℃ / 90%RH for 1000 hours and observe the change in resistivity. Each sample was tested in parallel 5 times and the average value was recorded.

[0125] Bending resistance test: After subjecting the substrate coated with the conductive silver paste composition to 100 bending cycles, the resistivity of the sample after the bending cycles was measured. The change in resistivity was used to represent the bending resistance of the conductive silver paste composition film. The smaller the change in resistance, the better the bending resistance of the sample. The specific test results are shown in Table 1 below.

[0126] Table 1 Performance testing of the conductive silver paste compositions prepared in Examples 1-3 and Comparative Examples 1-5

[0127]

[0128] As can be seen from the data in Table 1, the conductive silver paste compositions prepared in Examples 1-3 have high stability and conductivity.

[0129] In Comparative Example 1, replacing the tannic acid-modified silver nanowires with composite silver nanowires prepared from silver nanowires and adding them to the conductive silver paste composition resulted in a decrease in conductivity. This demonstrates that surface modification of silver nanowires with tannic acid is beneficial for the in-situ synthesis of copper nanowires on the surface of silver nanowires, forming a core-shell structure, which improves the conductivity and mechanical properties of the silver paste composition. Furthermore, by synthesizing copper nanowires in situ on the surface of silver nanowires, the copper nanowires are uniformly dispersed on the surface of the silver nanowires, preventing the copper nanowires from detaching and migrating into the silver paste composition, agglomerating in the silver paste composition, and affecting the conductivity of the silver paste composition.

[0130] In Comparative Example 2, when silver nanowires loaded with copper nanowires were replaced with tannic acid-modified silver nanowires, the composite silver nanowires prepared and added to the conductive silver paste composition showed a decrease in bending resistance and conductivity. This demonstrates that the core-shell structured nanowires have an excellent aspect ratio and can form a network structure in the silver paste composition that can absorb and weaken external stress, thereby improving the mechanical strength of the polymer-type silver paste composition after curing and avoiding poor mechanical properties after curing, which can easily break at high temperatures and affect conductivity.

[0131] In Comparative Example 3, when composite silver nanowires were replaced with silver nanowires loaded with copper nanowires, the composite silver nanowires added to the conductive silver paste composition showed a decrease in their bending resistance and conductivity. This demonstrates that the synthesis of porous carbon structures on the surface of copper-loaded silver nanowires can hinder the penetration and contact of oxygen and water molecules into the copper-loaded silver nanowires, preventing the copper-loaded silver nanowires from easily contacting oxygen in the air to form oxides, which would reduce the conductivity of the silver paste composition. Furthermore, porous carbon, as a carbon material, also has excellent conductivity and increases the contact area between the copper-loaded silver nanowires and the silver paste composition.

[0132] In Comparative Example 4, the composite layered material was replaced with graphene oxide nanosheets, and in Comparative Example 5, the composite layered material was replaced with sheet-like alumina added to the conductive silver paste composition. The mechanical properties of the composite layered material decreased, which proves that the composite layered material formed by sheet-like alumina intercalating with graphene oxide nanosheets can absorb and weaken the energy generated by external stress, prevent the crack propagation after the silver paste composition is cured, and improve the mechanical properties of the silver paste composition. Moreover, the composite layered material has a high barrier performance against oxygen and water molecules, further inhibiting the oxidation of the silver paste composition and improving the conductivity and system stability of the silver paste composition. In addition, the intercalation of sheet-like alumina with graphene oxide nanosheets avoids the stacking and agglomeration of graphene oxide nanosheets, which would result in poor system stability and reduced conductivity.

[0133] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0134] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A low-resistance polymer-type conductive silver paste composition, characterized in that, The raw materials include the following parts by weight: 40-50 parts polymer resin, 10-15 parts nano silver powder, 3-5 parts composite silver nanowires, 5-8 parts composite layered material, 3-5 parts aromatic polyisocyanate, 2-4 parts butyl citrate, and 6-10 parts ethylene glycol. Among them, the composite silver nanowires are obtained by in-situ synthesis of nano-copper on the surface of tannic acid-modified silver nanowires, followed by mixing and reaction with rice husk powder. The composite layered material is obtained by intercalating sheet-like alumina with graphene oxide nanosheets; The composite silver nanowires are specifically prepared by the following steps: A1. Add tannic acid to ethanol and stir until completely dissolved. Add silver nanowires, stir evenly, centrifuge to collect the precipitate, wash the precipitate, and dry it to obtain tannic acid modified silver nanowires. A2. Add copper chloride to deionized water and stir until homogeneous. Add tannic acid-modified silver nanowires and stir. Add glucose and stir until the reaction is complete. Cool to room temperature, filter, wash and dry to obtain silver nanowires loaded with copper nanowires. A3. Add silver nanowires loaded with copper nanoparticles, rice husk powder, and citric acid to ethanol, stir until homogeneous, add hydrochloric acid, stir until the reaction is complete, filter, wash, dry, place in a tube furnace, add potassium hydroxide solution, purge with nitrogen gas, carbonize at 700-750℃ for 4-5 hours, cool to room temperature, remove, wash, and dry to obtain composite silver nanowires.

2. The low-resistance polymer-type conductive silver paste composition according to claim 1, characterized in that, In step A1, the ratio of tannic acid, ethanol and silver nanowires is (1-1.2)g:(5-6)g:(1.2-1.4)g.

3. The low-resistance polymer-type conductive silver paste composition according to claim 1, characterized in that, In step A2, the ratio of copper chloride, deionized water, tannic acid-modified silver nanowires and glucose is (1-3)g:(45-55)mL:(5.2-5.4)g:(1-1.2)g.

4. The low-resistance polymer-type conductive silver paste composition according to claim 1, characterized in that, In step A3, the ratio of the amount of silver nanowires loaded with copper nanoparticles, rice husk powder, citric acid, ethanol, hydrochloric acid and potassium hydroxide solution is (5.5-5.7)g:(2.2-2.4)g:(0.4-0.6)g:(55-65)mL:(0.1-0.3)mL:(4-5)mL.

5. The low-resistance polymer-type conductive silver paste composition according to claim 1, characterized in that, The composite layered material is prepared by the following steps: After cleaning the graphene oxide nanosheets with hydrochloric acid, they were washed with deionized water until the pH of the washing solution was neutral. The nanosheets were then added to the deionized water and stirred evenly. Flake alumina was added and ultrasonically treated at 40-60 kHz for 20-30 min. After filtration, washing, and drying, the wear-resistant filler was obtained.

6. The low-resistance polymer-type conductive silver paste composition according to claim 5, characterized in that, The ratio of graphene oxide nanosheets, deionized water, and sheet alumina is (1.4-1.6)g:(90-110)mL:(0.8-1)g.

7. The low-resistance polymer-type conductive silver paste composition according to claim 1, characterized in that, The polymer resin is a hydroxyl acrylic resin with a hydroxyl value of 80-100 mg KOH / g.

8. The low-resistance polymer-type conductive silver paste composition according to claim 1, characterized in that, The aromatic polyisocyanate is selected from toluene diisocyanate and / or diphenylmethane diisocyanate.

9. A method for preparing a low-resistance polymer-type conductive silver paste composition according to any one of claims 1-8, characterized in that, The preparation steps include the following: Nano-silver powder, composite silver nanowires, composite layered materials, butyl citrate and ethylene glycol are mixed and stirred at 1000-1500 r / min for 5-10 min to obtain a mixture. Polymer resin and aromatic polyisocyanate are added to the mixture and stirred at 500-800 r / min for 15-20 min to obtain a conductive silver paste composition.

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