A low-temperature printing conductive silver paste and preparation method thereof

Abstract

The invention discloses a low-temperature printed conductive silver paste and a preparation method thereof. The conductive silver paste comprises the following raw materials in parts by weight: 10-15 parts of functionalized polyurethane, 3-5 parts of 1,6-hexanediol diacrylate, 3-5 parts of hydroxyethyl methacrylate, 0.1-0.3 parts of a photoinitiator, 5-8 parts of silver nitrate, 55-65 parts of silver powder, and 10-15 parts of ethyl acetate. During the curing process of the conductive silver paste, the imidazole groups on the functionalized polyurethane can be complexed with silver ions in the silver nitrate to form a silver organic framework, which is combined with the polyaniline and silver powder in the side chain of the functionalized polyurethane to ensure the conductivity of the material. At the same time, the unsaturated double bonds contained in the functionalized polyurethane molecular chain can be polymerized with 1,6-hexanediol diacrylate and hydroxyethyl methacrylate under the action of the photoinitiator to form a semi-interpenetrating grid structure, and at the same time, a cage-type silsesquioxane is coated to form a core-shell structure, thereby improving the mechanical properties of the conductive silver paste cured film.

Description

Technical Field

[0001] The invention relates to the field of printed conductive silver paste, and in particular to a low-temperature printed conductive silver paste and a preparation method thereof. Background Art

[0002] Conductive silver paste integrates electronics, chemicals, and metallurgy, and is a fundamental material for today's electronic technology industry. As materials continue to move toward lighter, thinner, and more intelligent materials, there is an urgent need to develop high-performance, low-cost conductive silver paste to meet increasingly stringent development requirements. UV-curable conductive silver paste also features instant curing, high yield, significant shielding effect, low requirements for printed substrates, no need for high-temperature sintering, and simplified traditional processes, which can greatly enhance the competitiveness of electronic products. Due to the characteristics of its curing method, UV-curable silver paste will be increasingly used in advanced processes such as ultra-narrow connections, ultra-thin electrodes, and rapid solderless assembly of electronic devices. Current reports on UV-curable silver paste indicate that its mechanical properties decrease due to the addition of silver powder, and it is prone to breakage or increased resistance after repeated bending, which in turn affects normal use. Summary of the Invention

[0003] The purpose of the present invention is to provide a low-temperature printed conductive silver paste and a preparation method thereof, so as to solve the problem that the current low-temperature conductive silver paste has poor anti-bending effect.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for preparing a low-temperature printed conductive silver paste comprises the following steps:

[0006] Step A1: Polyethylene glycol, a modified monomer, isophorone diisocyanate, and DMF are uniformly mixed, stirred at a speed of 120-150 r / min and a temperature of 40-50° C., and dibutyltin dilaurate is added, and the reaction is carried out for 30-40 minutes. Hydroxyl-terminated polybutadiene is added, and the reaction is continued for 30-40 minutes. 4-aminoimidazole is added, and the reaction is continued for 1-1.5 hours to prepare a modified polyurethane;

[0007] Step A2: The modified polyurethane and DMF are uniformly mixed, and ammonium persulfate and aniline are added under stirring at a speed of 60-80 r / min, a temperature of 10-15° C., and a pH of 1-2, and the mixture is reacted for 20-25 hours to obtain a functionalized polyurethane.

[0008] Step A3: Weigh the following raw materials in parts by weight: 10-15 parts of functionalized polyurethane, 3-5 parts of 1,6-hexanediol diacrylate, 3-5 parts of hydroxyethyl methacrylate, 0.1-0.3 parts of photoinitiator, 5-8 parts of silver nitrate, 55-65 parts of silver powder, and 10-15 parts of ethyl acetate, and mix the raw materials evenly to prepare a low-temperature printing conductive silver paste.

[0009] Furthermore, the mass ratio of the polyethylene glycol, modified monomer, isophorone diisocyanate, hydroxy-terminated polybutadiene and 4-aminoimidazole described in step A1 is 12:20:35:25:5, and the amount of dibutyltin dilaurate is 1% by mass of isophorone diisocyanate.

[0010] Furthermore, the mass ratio of the modified polyurethane and aniline in step A2 is 15:4, and the amount of potassium persulfate used is 5‰ of the mass of aniline.

[0011] Furthermore, the modified monomer is prepared by the following steps:

[0012] Step B1: 4-hydroxyphthalic anhydride and DMF are mixed uniformly, stirred at a speed of 120-150 r / min and a temperature of 0°C, and aniline is added, and the reaction is carried out for 1-1.5 hours. The temperature is raised to 60-65°C, and triethylamine, acetic anhydride, and nickel acetate are added. The reaction is continued for 2-3 hours to obtain intermediate 1. Intermediate 1, allyl chloride, potassium carbonate, and DMF are mixed uniformly, and the reaction is carried out at a speed of 200-300 r / min and a temperature of 70-75°C for 10-15 hours to obtain intermediate 2;

[0013] Step B2: Intermediate 2, 3-mercaptopropyltrimethoxysilane, benzophenone and DMF are mixed uniformly, and the mixture is reacted for 5-7 hours at a speed of 120-150 r / min, a temperature of 20-25°C, and irradiation with 365 nm ultraviolet light to obtain intermediate 3. Intermediate 3, isopropanol, sodium hydroxide and deionized water are mixed, and the mixture is reacted for 3-5 hours at a speed of 150-200 r / min and a temperature of 85-90°C. The mixture is then cooled to 20-25°C and reacted for 10-15 hours to obtain functionalized sodium cyclotetrasiloxane tetrasilanolate.

[0014] Step B3: Functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine and tetrahydrofuran are mixed, stirred and methyldichlorosilane is added at a speed of 150-200 r / min and a temperature of 0°C, and the reaction is carried out for 3-5 hours. The temperature is raised to 20-25°C and the reaction is carried out for 20-24 hours to obtain a functionalized cage-type silsesquioxane. The functionalized cage-type silsesquioxane, allyl alcohol, chloroplatinic acid and DMF are mixed evenly, and the reaction is carried out at a speed of 120-150 r / min and a temperature of 70-80°C for 8-10 hours to obtain a modified monomer.

[0015] Furthermore, the amount ratio of 4-hydroxyphthalic anhydride, DMF, aniline, triethylamine, acetic anhydride and nickel acetate in step B1 is 50 mmol:50 mL:50 mmol:5 mL:12 mL:3.5 g, and the molar ratio of intermediate 1, allyl chloride and potassium carbonate is 1:1:1.1.

[0016] Furthermore, the molar ratio of the intermediate 2 and 3-mercaptopropyltrimethoxysilane described in step B2 is 1:1, the amount of benzophenone is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane, and the amount ratio of intermediate 3, isopropanol, sodium hydroxide and deionized water is 6mmol:6mL:7mmol:4mmol.

[0017] Furthermore, the mass ratio of the functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine, tetrahydrofuran and methyldichlorosilane in step B3 is 15:4:30:3.5, the molar ratio of the functionalized cage-type silsesquioxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol.

[0018] Beneficial effects of the present invention: A low-temperature printing conductive silver paste disclosed in the present application comprises the following raw materials: functionalized polyurethane, 1,6-hexanediol diacrylate, hydroxyethyl methacrylate, a photoinitiator, silver nitrate, silver powder and ethyl acetate; the functionalized polyurethane is reacted with polyethylene glycol, a modified monomer and isophorone diisocyanate to prepare a polyurethane prepolymer, which is then chain extended with terminal hydroxyl polybutadiene and finally end-capped with 4-aminoimidazole to prepare a modified polyurethane; the modified polyurethane is reacted with aniline to form a polyaniline segment in the side chain of the modified polyurethane to prepare the functionalized polyurethane.

[0019] The modified monomer is prepared by using 4-hydroxyphthalic anhydride and aniline as raw materials, and the anhydride on the 4-hydroxyphthalic anhydride reacts with the amino group on the aniline to obtain intermediate 1, and the intermediate 1 is reacted with allyl chloride to react the hydroxyl group on the intermediate 1 with the chlorine atom site on the allyl chloride to obtain intermediate 2, and the intermediate 2 is reacted with 3-mercaptopropyltrimethoxysilane to react the double bond on the intermediate 2 with the mercapto group on the 3-mercaptopropyltrimethoxysilane to obtain intermediate The intermediate 3 is hydrolyzed and polycondensed to obtain a functionalized sodium cyclotetrasiloxane tetrasiloxide, the functionalized sodium cyclotetrasiloxane tetrasiloxide is reacted with methyldichlorosilane, so that the sodium siloxide on the functionalized sodium cyclotetrasiloxane tetrasiloxide reacts with the chlorine atom site on the methyldichlorosilane to obtain a functionalized cage-type silsesquioxane, and the functionalized cage-type silsesquioxane is reacted with allyl alcohol so that the Si-H bond on the functionalized cage-type silsesquioxane reacts with the double bond on the allyl alcohol to obtain a modified monomer.

[0020] During the curing process of the conductive silver paste, the imidazole groups on the functionalized polyurethane can complex with the silver ions in the silver nitrate to form a silver organic framework, which, combined with the polyaniline and silver powder on the side chains of the functionalized polyurethane, can form a stable conductive path after the conductive silver paste is cured, thereby ensuring conductivity. At the same time, the unsaturated double bonds on the functionalized polyurethane molecular chain can polymerize with 1,6-hexanediol diacrylate and hydroxyethyl methacrylate under the action of a photoinitiator, forming a semi-interpenetrating grid structure with the polyaniline on the side chain, and at the same time being coated with a cage-type silsesquioxane to form a core-shell structure, thereby improving the mechanical properties of the conductive silver paste cured film. DETAILED DESCRIPTION

[0021] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0022] Example 1: A method for preparing a low-temperature printed conductive silver paste, comprising the following steps:

[0023] Step A1: Polyethylene glycol, a modified monomer, isophorone diisocyanate, and DMF were uniformly mixed, and dibutyltin dilaurate was added under stirring at a speed of 120 r / min and a temperature of 40° C. The mixture was reacted for 30 minutes, hydroxy-terminated polybutadiene was added, and the reaction was continued for 30 minutes. 4-aminoimidazole was added, and the reaction was continued for 1 hour to obtain a modified polyurethane.

[0024] Step A2: The modified polyurethane and DMF were uniformly mixed, and ammonium persulfate and aniline were added under stirring at a speed of 60 r / min, a temperature of 10° C., and a pH of 1. The mixture was reacted for 20 hours to obtain a functionalized polyurethane.

[0025] Step A3: Weigh the following raw materials in parts by weight: 10 parts of functionalized polyurethane, 3 parts of 1,6-hexanediol diacrylate, 3 parts of hydroxyethyl methacrylate, 0.1 parts of photoinitiator, 5 parts of silver nitrate, 55 parts of silver powder and 10 parts of ethyl acetate, mix the raw materials evenly to prepare a low-temperature printing conductive silver paste.

[0026] The mass ratio of the polyethylene glycol, modified monomer, isophorone diisocyanate, hydroxyl-terminated polybutadiene and 4-aminoimidazole described in step A1 is 12:20:35:25:5, the amount of dibutyltin dilaurate is 1% by mass of isophorone diisocyanate, the molecular weight of the polyethylene glycol is 2000, and the molecular weight of the hydroxyl-terminated polybutadiene is 2000.

[0027] The mass ratio of the modified polyurethane and aniline in step A2 is 15:4, and the amount of potassium persulfate used is 5‰ of the mass of aniline.

[0028] The photoinitiator described in step A3 is 819.

[0029] The modified monomer is prepared by the following steps:

[0030] Step B1: 4-hydroxyphthalic anhydride and DMF were mixed uniformly, stirred at a speed of 120 r / min and a temperature of 0°C, and aniline was added, and the reaction was carried out for 1 hour. The temperature was raised to 60°C, and triethylamine, acetic anhydride, and nickel acetate were added. The reaction was continued for 2 hours to obtain intermediate 1. Intermediate 1, allyl chloride, potassium carbonate, and DMF were mixed uniformly, and the reaction was carried out at a speed of 200 r / min and a temperature of 70°C for 10 hours to obtain intermediate 2;

[0031] Step B2: Intermediate 2, 3-mercaptopropyltrimethoxysilane, benzophenone and DMF were mixed uniformly, and the mixture was reacted for 5 hours at a speed of 120 r / min, a temperature of 20°C and irradiation with 365 nm ultraviolet light to obtain intermediate 3. Intermediate 3, isopropanol, sodium hydroxide and deionized water were mixed, and the mixture was reacted for 3 hours at a speed of 150 r / min and a temperature of 85°C. The mixture was then cooled to 20°C and reacted for 10 hours to obtain functionalized sodium tetrasiloxide of cyclotetrasiloxane;

[0032] Step B3: Functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine and tetrahydrofuran are mixed, stirred and methyldichlorosilane is added at a speed of 150 r / min and a temperature of 0°C, and the reaction is carried out for 3 hours. The temperature is then raised to 20°C and the reaction is carried out for 20 hours to obtain a functionalized cage-type silsesquioxane. The functionalized cage-type silsesquioxane, allyl alcohol, chloroplatinic acid and DMF are mixed evenly, and the reaction is carried out at a speed of 120 r / min and a temperature of 70°C for 8 hours to obtain a modified monomer.

[0033] The amount ratio of 4-hydroxyphthalic anhydride, DMF, aniline, triethylamine, acetic anhydride and nickel acetate in step B1 is 50mmol:50mL:50mmol:5mL:12mL:3.5g, and the molar ratio of intermediate 1, allyl chloride and potassium carbonate is 1:1:1.1.

[0034] The molar ratio of intermediate 2 and 3-mercaptopropyltrimethoxysilane described in step B2 is 1:1, the amount of benzophenone is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane, and the amount ratio of intermediate 3, isopropanol, sodium hydroxide and deionized water is 6mmol:6mL:7mmol:4mmol.

[0035] The mass ratio of the functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine, tetrahydrofuran and methyldichlorosilane described in step B3 is 15:4:30:3.5, the molar ratio of the functionalized cage-type silsesquioxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol.

[0036] Example 2: A method for preparing a low-temperature printed conductive silver paste, comprising the following steps:

[0037] Step A1: Polyethylene glycol, a modified monomer, isophorone diisocyanate, and DMF were uniformly mixed, and dibutyltin dilaurate was added under stirring at a speed of 120 r / min and a temperature of 45° C. The mixture was reacted for 35 minutes, hydroxy-terminated polybutadiene was added, and the reaction was continued for 35 minutes. 4-aminoimidazole was added, and the reaction was continued for 1.5 hours to obtain a modified polyurethane.

[0038] Step A2: The modified polyurethane and DMF were uniformly mixed, and ammonium persulfate and aniline were added under stirring at a speed of 60 r / min, a temperature of 15° C., and a pH of 1.5, and the mixture was reacted for 25 hours to obtain a functionalized polyurethane.

[0039] Step A3: Weigh the following raw materials in parts by weight: 13 parts of functionalized polyurethane, 4 parts of 1,6-hexanediol diacrylate, 4 parts of hydroxyethyl methacrylate, 0.2 parts of photoinitiator, 6 parts of silver nitrate, 60 parts of silver powder and 13 parts of ethyl acetate, mix the raw materials evenly to prepare a low-temperature printing conductive silver paste.

[0040] The mass ratio of the polyethylene glycol, modified monomer, isophorone diisocyanate, hydroxyl-terminated polybutadiene and 4-aminoimidazole described in step A1 is 12:20:35:25:5, the amount of dibutyltin dilaurate is 1% by mass of isophorone diisocyanate, the molecular weight of the polyethylene glycol is 2000, and the molecular weight of the hydroxyl-terminated polybutadiene is 2000.

[0041] The mass ratio of the modified polyurethane and aniline in step A2 is 15:4, and the amount of potassium persulfate used is 5‰ of the mass of aniline.

[0042] The photoinitiator described in step A3 is 1173.

[0043] The modified monomer is prepared by the following steps:

[0044] Step B1: 4-hydroxyphthalic anhydride and DMF were mixed uniformly, stirred at a speed of 120 r / min and a temperature of 0°C, and aniline was added, and the reaction was carried out for 1.5 hours. The temperature was raised to 60°C, and triethylamine, acetic anhydride, and nickel acetate were added. The reaction was continued for 3 hours to obtain intermediate 1. Intermediate 1, allyl chloride, potassium carbonate, and DMF were mixed uniformly, and the reaction was carried out at a speed of 200 r / min and a temperature of 75°C for 10 hours to obtain intermediate 2;

[0045] Step B2: Intermediate 2, 3-mercaptopropyltrimethoxysilane, benzophenone and DMF were mixed uniformly, and the mixture was reacted for 6 hours at a speed of 120 r / min, a temperature of 25°C and irradiation with 365 nm ultraviolet light to obtain intermediate 3. Intermediate 3, isopropanol, sodium hydroxide and deionized water were mixed, and the mixture was reacted for 4 hours at a speed of 150 r / min and a temperature of 90°C. The mixture was then cooled to 25°C and reacted for 10 hours to obtain functionalized sodium cyclotetrasiloxane tetrasiloxide.

[0046] Step B3: Functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine and tetrahydrofuran are mixed, stirred and methyldichlorosilane is added at a speed of 200 r / min and a temperature of 0°C, and the reaction is carried out for 4 hours. The temperature is then raised to 25°C and the reaction is carried out for 20 hours to obtain a functionalized cage-type silsesquioxane. The functionalized cage-type silsesquioxane, allyl alcohol, chloroplatinic acid and DMF are mixed evenly, and the reaction is carried out at a speed of 150 r / min and a temperature of 75°C for 9 hours to obtain a modified monomer.

[0047] The amount ratio of 4-hydroxyphthalic anhydride, DMF, aniline, triethylamine, acetic anhydride and nickel acetate in step B1 is 50mmol:50mL:50mmol:5mL:12mL:3.5g, and the molar ratio of intermediate 1, allyl chloride and potassium carbonate is 1:1:1.1.

[0048] The molar ratio of intermediate 2 and 3-mercaptopropyltrimethoxysilane described in step B2 is 1:1, the amount of benzophenone is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane, and the amount ratio of intermediate 3, isopropanol, sodium hydroxide and deionized water is 6mmol:6mL:7mmol:4mmol.

[0049] The mass ratio of the functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine, tetrahydrofuran and methyldichlorosilane described in step B3 is 15:4:30:3.5, the molar ratio of the functionalized cage-type silsesquioxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol.

[0050] Example 3: A method for preparing a low-temperature printed conductive silver paste, comprising the following steps:

[0051] Step A1: Polyethylene glycol, a modified monomer, isophorone diisocyanate, and DMF were uniformly mixed, and dibutyltin dilaurate was added under stirring at a speed of 150 r / min and a temperature of 50° C. The mixture was reacted for 40 minutes, hydroxy-terminated polybutadiene was added, and the reaction was continued for 40 minutes. 4-aminoimidazole was added, and the reaction was continued for 1.5 hours to obtain a modified polyurethane.

[0052] Step A2: The modified polyurethane and DMF were uniformly mixed, and ammonium persulfate and aniline were added under stirring at a speed of 80 r / min, a temperature of 15° C., and a pH of 2. The mixture was reacted for 25 hours to obtain a functionalized polyurethane.

[0053] Step A3: Weigh the following raw materials in parts by weight: 15 parts of functionalized polyurethane, 5 parts of 1,6-hexanediol diacrylate, 5 parts of hydroxyethyl methacrylate, 0.3 parts of photoinitiator, 8 parts of silver nitrate, 65 parts of silver powder and 15 parts of ethyl acetate, mix the raw materials evenly to prepare a low-temperature printing conductive silver paste.

[0054] The mass ratio of the polyethylene glycol, modified monomer, isophorone diisocyanate, hydroxyl-terminated polybutadiene and 4-aminoimidazole described in step A1 is 12:20:35:25:5, the amount of dibutyltin dilaurate is 1% by mass of isophorone diisocyanate, the molecular weight of the polyethylene glycol is 2000, and the molecular weight of the hydroxyl-terminated polybutadiene is 2000.

[0055] The mass ratio of the modified polyurethane and aniline in step A2 is 15:4, and the amount of potassium persulfate used is 5‰ of the mass of aniline.

[0056] The photoinitiator described in step A3 is 2959.

[0057] The modified monomer is prepared by the following steps:

[0058] Step B1: 4-hydroxyphthalic anhydride and DMF were mixed uniformly, stirred at a speed of 150 r / min and a temperature of 0°C, and aniline was added, and the reaction was carried out for 1.5 hours. The temperature was raised to 65°C, and triethylamine, acetic anhydride, and nickel acetate were added. The reaction was continued for 3 hours to obtain intermediate 1. Intermediate 1, allyl chloride, potassium carbonate, and DMF were mixed uniformly, and the reaction was carried out at a speed of 300 r / min and a temperature of 75°C for 15 hours to obtain intermediate 2;

[0059] Step B2: Intermediate 2, 3-mercaptopropyltrimethoxysilane, benzophenone and DMF were mixed uniformly, and the mixture was reacted for 7 hours at a speed of 150 r / min, a temperature of 25°C and irradiation with 365 nm ultraviolet light to obtain intermediate 3. Intermediate 3, isopropanol, sodium hydroxide and deionized water were mixed, and the mixture was reacted for 5 hours at a speed of 200 r / min and a temperature of 90°C. After that, the mixture was cooled to 25°C and reacted for 15 hours to obtain functionalized sodium tetrasiloxide of cyclotetrasiloxane;

[0060] Step B3: Functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine and tetrahydrofuran are mixed, stirred and methyldichlorosilane is added at a speed of 200 r / min and a temperature of 0°C, and the reaction is carried out for 5 hours. The temperature is then raised to 25°C and the reaction is carried out for 24 hours to obtain a functionalized cage-type silsesquioxane. The functionalized cage-type silsesquioxane, allyl alcohol, chloroplatinic acid and DMF are mixed evenly, and the reaction is carried out at a speed of 150 r / min and a temperature of 80°C for 10 hours to obtain a modified monomer.

[0061] The amount ratio of 4-hydroxyphthalic anhydride, DMF, aniline, triethylamine, acetic anhydride and nickel acetate in step B1 is 50mmol:50mL:50mmol:5mL:12mL:3.5g, and the molar ratio of intermediate 1, allyl chloride and potassium carbonate is 1:1:1.1.

[0062] The molar ratio of intermediate 2 and 3-mercaptopropyltrimethoxysilane described in step B2 is 1:1, the amount of benzophenone is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane, and the amount ratio of intermediate 3, isopropanol, sodium hydroxide and deionized water is 6mmol:6mL:7mmol:4mmol.

[0063] The mass ratio of the functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine, tetrahydrofuran and methyldichlorosilane described in step B3 is 15:4:30:3.5, the molar ratio of the functionalized cage-type silsesquioxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of allyl alcohol.

[0064] Comparative Example 1: Compared with Example 1, this comparative example did not add silver nitrate, and the remaining steps were the same.

[0065] Comparative Example 2: Compared with Example 1, this comparative example uses modified polyurethane instead of functional polyurethane, and the remaining steps are the same.

[0066] Comparative Example 3: Compared with Example 1, no modifying monomer was added to this comparative example, and the remaining steps were the same.

[0067] The conductive silver paste prepared in Examples 1-3 and Comparative Examples 1-3 was brushed onto a PET film with a thickness of 50 μm and irradiated under 365 nm ultraviolet light for 30 seconds to prepare a sample. The sample was tested for resistivity using an RTS-8 four-probe tester. The conductive silver paste was made into a wire with a width of 1 mm and a length of 100 mm. The wire was symmetrically bent 180°, and a weight was pressed on the wire with a pressure of 5.5 kPa for 1 minute. The wire was then bent 180° in the opposite direction and held for 1 minute. The bending was repeated 10 times, and the resistivity decrease rate was detected. The test results are shown in Table 1 below.

[0068] Table 1

[0069] It can be seen from Table 1 above that the present invention has good electrical conductivity and anti-bending effect.

[0070] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a low-temperature printed conductive silver paste, characterized in that: Step A1: Polyethylene glycol, a modified monomer, isophorone diisocyanate, and DMF are uniformly mixed, stirred at a speed of 120-150 r / min and a temperature of 40-50° C., and dibutyltin dilaurate is added, and the reaction is carried out for 30-40 minutes. Hydroxyl-terminated polybutadiene is added, and the reaction is continued for 30-40 minutes. 4-aminoimidazole is added, and the reaction is continued for 1-1.5 hours to prepare a modified polyurethane; Step A2: The modified polyurethane and DMF are uniformly mixed, and ammonium persulfate and aniline are added under stirring at a speed of 60-80 r / min, a temperature of 10-15° C., and a pH of 1-2, and the mixture is reacted for 20-25 hours to obtain a functionalized polyurethane. Step A3: Weigh the following raw materials in parts by weight: 10-15 parts of functionalized polyurethane, 3-5 parts of 1,6-hexanediol diacrylate, 3-5 parts of hydroxyethyl methacrylate, 0.1-0.3 parts of photoinitiator, 5-8 parts of silver nitrate, 55-65 parts of silver powder, and 10-15 parts of ethyl acetate, and mix the raw materials uniformly to prepare a low-temperature printing conductive silver paste; The mass ratio of the polyethylene glycol, modified monomer, isophorone diisocyanate, hydroxy-terminated polybutadiene, and 4-aminoimidazole described in step A1 is 12:20:35:25:5; The mass ratio of the modified polyurethane and aniline in step A2 is 15:4; The modified monomer is prepared by the following steps: Step B1: 4-hydroxyphthalic anhydride and DMF are mixed uniformly, stirred at a speed of 120-150 r / min and a temperature of 0°C, and aniline is added, and the reaction is carried out for 1-1.5 hours. The temperature is raised to 60-65°C, and triethylamine, acetic anhydride, and nickel acetate are added. The reaction is continued for 2-3 hours to obtain intermediate 1. Intermediate 1, allyl chloride, potassium carbonate, and DMF are mixed uniformly, and the reaction is carried out at a speed of 200-300 r / min and a temperature of 70-75°C for 10-15 hours to obtain intermediate 2; Step B2: Intermediate 2, 3-mercaptopropyltrimethoxysilane, benzophenone and DMF are mixed uniformly, and the mixture is reacted for 5-7 hours at a speed of 120-150 r / min, a temperature of 20-25°C, and irradiation with 365 nm ultraviolet light to obtain intermediate 3. Intermediate 3, isopropanol, sodium hydroxide and deionized water are mixed, and the mixture is reacted for 3-5 hours at a speed of 150-200 r / min and a temperature of 85-90°C. The mixture is then cooled to 20-25°C and reacted for 10-15 hours to obtain functionalized sodium cyclotetrasiloxane tetrasilanolate. Step B3: functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine, and tetrahydrofuran are mixed, stirred at a speed of 150-200 r / min and a temperature of 0° C., and methyldichlorosilane is added. The mixture is reacted for 3-5 hours, and then the temperature is raised to 20-25° C. and the reaction is carried out for 20-24 hours to obtain a functionalized cage-type silsesquioxane. The functionalized cage-type silsesquioxane, allyl alcohol, chloroplatinic acid, and DMF are uniformly mixed, and the mixture is reacted at a speed of 120-150 r / min and a temperature of 70-80° C. for 8-10 hours to obtain a modified monomer. The amount ratio of 4-hydroxyphthalic anhydride, DMF, aniline, triethylamine, acetic anhydride and nickel acetate described in step B1 is 50mmol:50mL:50mmol:5mL:12mL:3.5g, and the molar ratio of intermediate 1, allyl chloride and potassium carbonate is 1:1:1.1; The molar ratio of intermediate 2 and 3-mercaptopropyltrimethoxysilane in step B2 is 1:1, and the amount ratio of intermediate 3, isopropyl alcohol, sodium hydroxide and deionized water is 6 mmol:6 mL:7 mmol:4 mmol; The mass ratio of the functionalized cyclotetrasiloxane sodium tetrasiloxide, triethylamine, tetrahydrofuran and methyldichlorosilane in step B3 is 15:4:30:3.5, and the molar ratio of the functionalized cage silsesquioxane and allyl alcohol is 1:

2.

2. The method for preparing a low-temperature printed conductive silver paste according to claim 1, wherein: The amount of dibutyltin dilaurate described in step A1 is 1% by mass of isophorone diisocyanate.

3. The method for preparing a low-temperature printed conductive silver paste according to claim 1, wherein: The amount of ammonium persulfate used in step A2 is 5‰ of the mass of aniline.

4. The method for preparing a low-temperature printed conductive silver paste according to claim 1, wherein: The amount of benzophenone used in step B2 is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane.

5. The method for preparing a low-temperature printed conductive silver paste according to claim 1, wherein: The amount of chloroplatinic acid used in step B3 is 1‰ of the mass of allyl alcohol.

6. A low-temperature printed conductive silver paste, characterized in that: Prepared according to any one of claims 1 to 5.