Nano-material-containing electronic glue for flexible circuit manufacturing and preparation method thereof

Abstract

The invention relates to the technical field of electronic glue, and discloses nano-material-containing electronic glue for manufacturing a flexible circuit and a preparation method of the nano-material-containing electronic glue. According to the invention, the modified polyurethane matrix, the conductive nano filler, the photoinitiator and the flame retardant are mixed to obtain the nano-material-containing electronic glue for flexible circuit manufacturing. Phosphorus oxide released by the phosphorus element at a high temperature reacts with active free radicals in a combustion chain, so that a flame-retardant effect is achieved; the silicon element realizes flame retardance through surface migration and carbon layer protection; boric acid ester is melted at high temperature to form a compact glassy covering layer, so that oxygen is isolated from the material; nitrogen elements in quaternary ammonium salt, triazinyl and pyridyl release non-combustible gas after being heated and decomposed, the concentration of the combustible gas is diluted, and the flame-retardant effect is achieved. Pure Ag nano-particles are easy to agglomerate due to high surface energy, Fe3O4 serves as an inner core, the particle size can be increased, the surface energy of an Ag shell layer can be reduced, the Ag shell layer can be distributed more uniformly, effective contact points are increased, and the conductivity is improved.

Description

Technical Field

[0001] This invention relates to the field of electronic adhesive technology, specifically to an electronic adhesive containing nanomaterials for flexible circuit manufacturing and its preparation method. Background Technology

[0002] Flexible printed circuit boards (PCBs) are made of materials that are soft, flexible, and foldable, allowing them to be placed in any configuration within electronic products, significantly reducing their size. With the rapid development of flexible electronics technology, PCBs are increasingly used in wearable devices, foldable phones, and medical sensors. The substrate for flexible PCBs is typically made by bonding an insulating plastic film to roughened copper foil using a special adhesive. As public awareness of environmental protection continues to grow, photocuring systems are gaining increasing attention. Because photocuring systems do not contain volatile organic solvents, they are truly green and pollution-free. The perfect combination of UV curing and conductive polymers achieves high conductivity while prioritizing environmental protection, leading to its widespread application in various fields, such as UV-cured conductive adhesives, photocured conductive coatings, and conductive photoresists. UV-curable conductive adhesives used in flexible circuit manufacturing are special adhesives that cure rapidly under UV light, possessing both high conductivity and flexible bonding properties. Commonly used adhesives include acrylic adhesives, modified epoxy resin adhesives, modified nitrile adhesives, polyurethane adhesives, and acetal adhesives. These adhesives all exhibit varying degrees of flammability and poor flame retardancy. Patent CN105733469A discloses a UV-curable conductive adhesive and its preparation method. This invention provides a conductive adhesive that cures without high-temperature heating and exhibits excellent conductivity, but its flame retardant properties still need improvement. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides an electronic adhesive containing nanomaterials for flexible circuit fabrication and its preparation method. The electronic adhesive prepared by this invention exhibits excellent electrical conductivity while also possessing improved flame-retardant properties.

[0005] (II) Technical Solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: an electronic adhesive containing nanomaterials for the manufacture of flexible circuits, comprising the following weight components: 60-70 parts by weight of modified polyurethane matrix, 20-25 parts by weight of Ag@Fe3O4 conductive nanofiller, 0.2-0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone photoinitiator, and 4-8 parts by weight of borate triazine flame retardant.

[0007] Preferably, the preparation method of the Ag@Fe3O4 conductive nanofiller is as follows: 0.8-1.2g of Fe3O4 magnetic nanoparticles are immersed in 2-2.1mL of AgNO3 solution with a concentration of 0.48-0.52mol / L, and then reduced by electron beam irradiation to obtain Ag@Fe3O4 conductive nanofiller.

[0008] Preferably, the method for preparing the modified polyurethane matrix includes the following steps:

[0009] (1) Add 2.9-3g of N-methyldiethanolamine to 60-80mL of anhydrous ethanol solvent, stir to dissolve, and add 5.1-5.3g of 3-chloropropyltrimethoxysilane dropwise. After the addition is complete, heat to 76-82℃ and reflux for 14-18h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate.

[0010] (2) Under a nitrogen atmosphere, 4.4-4.5 g of silane quaternary ammonium salt intermediate and 0.8-1.2 mL of triethylamine catalyst were added to 40-50 mL of dichloromethane solvent and stirred at 8-12 °C until dissolved. 1.62-1.72 g of phenylphosphodichloro was added dropwise over a period of 20-35 min. After the addition was complete, the reaction was allowed to proceed for 10-14 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain a flame-retardant chain extender.

[0011] (3) Add 3.45-3.55g of isophorone diisocyanate, 4.8-5.2g of polytetramethylene ether glycol, 0.28-0.32g of 1,4-butanediol, and 0.01-0.02g of dibutyltin dilaurate catalyst to the reactor, heat to 78-84℃ and react for 1.5-2.5h, then add 0.36-0.44g of dimethylolpropionic acid and 0.75-0.8g of flame-retardant chain extender, and continue the reaction for 1-2h to obtain polyurethane. The ester prepolymer was cooled to 38-42℃, and 0.44-0.56g of pentaerythritol triacrylate was added to the polyurethane prepolymer. After reacting for 0.5-1h, 0.55-0.65g of dipentaerythritol hexaacrylate and 0.52-0.58g of dipropylene glycol diacrylate were added, and the mixture was stirred for 1-1.5h. Then, 0.27-0.35g of triethylamine and 15-20mL of deionized water were added, and the mixture was stirred for 20-40min to obtain the modified polyurethane matrix.

[0012] Preferably, the dropping time of 3-chloropropyltrimethoxysilane in step (1) is 0.5-1h.

[0013] Preferably, the preparation method of the borate triazine flame retardant includes the following steps:

[0014] S1. Dissolve 3.2-3.75 g of 2-bromo-5-hydroxypyridine and 6-6.2 g of pinacol diboronic acid ester in 80-100 mL of 1,4-dioxane solvent, add 1.45-1.55 g of catalyst and 8-8.2 g of potassium carbonate, and react at 95-105 °C for 3-5 h under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the borate ester intermediate.

[0015] S2. Add 2.5-2.56 g of cyanuric chloride to 30-40 mL of toluene solvent and stir to dissolve. Dissolve 12.3-12.5 g of borate intermediate and 4-4.4 g of triethylamine acid retardant in 50-80 mL of toluene solvent. At the reaction temperature, add the solution dropwise to the cyanuric chloride solution over a period of 40-50 min. After the addition is complete, allow the reaction to proceed for 8-10 h. After the reaction is complete, filter the solution and remove the solvent by rotary evaporation to obtain the borate triazine flame retardant.

[0016] Preferably, the catalyst in S1 is [1,1-bis(diphenylphosphine)ferrocene]palladium dichloride.

[0017] Preferably, the reaction temperature in S2 is 90-100℃.

[0018] Preferably, the preparation method of the electronic adhesive containing nanomaterials for flexible circuit manufacturing is as follows: add modified polyurethane matrix, Ag@Fe3O4 conductive nanofiller, 1-hydroxycyclohexylphenyl ketone photoinitiator, and borate triazine flame retardant to a reactor, stir and mix for 20-30 minutes to obtain the electronic adhesive containing nanomaterials for flexible circuit manufacturing.

[0019] (III) Beneficial Technical Effects

[0020] This invention obtains an electronic adhesive containing nanomaterials for flexible circuit manufacturing by mixing a modified polyurethane matrix, Ag@Fe3O4 conductive nanofiller, 1-hydroxycyclohexylphenyl ketone photoinitiator, and borate triazine flame retardant.

[0021] Phosphorus in flame-retardant chain extenders releases phosphorus oxides at high temperatures. These substances can rapidly react with active free radicals in the combustion chain, interrupting the combustion chain reaction and thus playing a flame-retardant role. Silicon mainly achieves flame retardancy through surface migration and char layer protection. During combustion, silicon-based flame retardants migrate to the material surface and form an inorganic protective layer containing Si-O or Si-C bonds at high temperatures, isolating oxygen and heat, while promoting char formation and inhibiting the release of thermal decomposition products, thereby improving the flame-retardant effect of electronic adhesives. Boronate triazine flame retardants melt at high temperatures, forming a dense glassy coating layer that adheres to the material surface, isolating oxygen from contact with the material, and hindering the diffusion of combustible volatiles to the combustion zone, inhibiting the continuation of combustion, thereby improving the flame-retardant performance of electronic adhesives. Nitrogen elements in quaternary ammonium salts, triazine groups, and pyridine groups release non-flammable gases after thermal decomposition, diluting the concentration of combustible gases and reducing the surface temperature of the material, thus playing a flame-retardant role. Ag@Fe3O4 has a core-shell structure. Pure Ag nanoparticles tend to agglomerate due to their high surface energy, which leads to the breakage of the conductive network. Fe3O4, as the core, can increase the particle volume, reduce the surface energy of the Ag shell, and reduce its agglomeration in the electronic adhesive. The improved dispersibility makes the Ag shell more uniformly distributed, increases the number of effective contact points, and thus improves the conductivity. Attached Figure Description

[0022] Figure 1 It is the synthetic reaction formula for flame-retardant chain extenders.

[0023] Figure 2 It is the synthetic reaction formula for borate triazine flame retardants. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] To better understand the above technical solutions, the following will provide a detailed description of the technical solutions in conjunction with the accompanying drawings and specific embodiments.

[0026] Example 1

[0027] (1) 0.8 g of Fe3O4 magnetic nanoparticles were immersed in 2 mL of AgNO3 solution with a concentration of 0.48 mol / L and reduced by electron beam irradiation to obtain Ag@Fe3O4 conductive nanofiller.

[0028] (2) Add 2.9 g of N-methyldiethanolamine to 60 mL of anhydrous ethanol solvent, stir to dissolve, add 5.1 g of 3-chloropropyltrimethoxysilane dropwise over a period of 0.5 h, and after the addition is complete, heat to 76 °C and reflux for 14 h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate.

[0029] (3) Under a nitrogen atmosphere, 4.4 g of silane quaternary ammonium salt intermediate and 0.8 mL of triethylamine catalyst were added to 40 mL of dichloromethane solvent and stirred at 8 °C until dissolved. 1.62 g of phenylphosphodichloro was added dropwise over a period of 20 min. After the addition was complete, the reaction was carried out for 10 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain a flame-retardant chain extender.

[0030] (4) Add 3.45g of isophorone diisocyanate, 4.8g of polytetramethylene ether glycol, 0.28g of 1,4-butanediol, and 0.01g of dibutyltin dilaurate catalyst to the reactor, heat to 78℃ and react for 1.5h, add 0.36g of dimethylolpropionic acid and 0.75g of flame retardant chain extender, and continue to react for 1h to obtain polyurethane prepolymer, cool to 38℃, add 0.44g of pentaerythritol triacrylate to the polyurethane prepolymer, react for 0.5h, add 0.55g of dipentaerythritol hexaacrylate and 0.52g of dipropylene glycol diacrylate, stir for 1h, add 0.27g of triethylamine and 15mL of deionized water, stir for 20min to obtain modified polyurethane matrix;

[0031] (5) Dissolve 3.2 g of 2-bromo-5-hydroxypyridine and 6 g of pinacol diborate in 80 mL of 1,4-dioxane solvent, add 1.45 g of [1,1-bis(diphenylphosphine)ferrocene]palladium dichloride catalyst and 8 g of potassium carbonate, and react at 95 °C for 3 h under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the borate intermediate.

[0032] (6) Add 2.5g of cyanuric chloride to 30mL of toluene solvent and stir to dissolve. Dissolve 12.3g of borate intermediate and 4g of triethylamine acid retardant in 50mL of toluene solvent. Add the solution dropwise at 90℃ for 40min. After the addition is complete, react for 8h. After the reaction is complete, filter and remove the solvent by rotary evaporation to obtain borate triazine flame retardant.

[0033] (7) Add 60 parts by weight of modified polyurethane matrix, 20 parts by weight of Ag@Fe3O4 conductive nanofiller, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone photoinitiator, and 4 parts by weight of borate triazine flame retardant to the reactor, stir and mix for 20 min to obtain an electronic adhesive containing nanomaterials for flexible circuit manufacturing.

[0034] Example 2

[0035] (1) 1.2 g of Fe3O4 magnetic nanoparticles were immersed in 2.1 mL of AgNO3 solution with a concentration of 0.52 mol / L and reduced by electron beam irradiation to obtain Ag@Fe3O4 conductive nanofiller.

[0036] (2) Add 3g of N-methyldiethanolamine to 80mL of anhydrous ethanol solvent, stir to dissolve, add 5.3g of 3-chloropropyltrimethoxysilane dropwise over 1h, and after the addition is complete, heat to 82℃ and reflux for 18h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate.

[0037] (3) Under a nitrogen atmosphere, 4.5 g of silane quaternary ammonium salt intermediate and 1.2 mL of triethylamine catalyst were added to 50 mL of dichloromethane solvent and stirred at 12 °C until dissolved. 1.72 g of phenylphosphodichloro was added dropwise over a period of 35 min. After the addition was complete, the reaction was carried out for 14 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain a flame-retardant chain extender.

[0038] (4) Add 3.55g of isophorone diisocyanate, 5.2g of polytetramethylene ether glycol, 0.32g of 1,4-butanediol, and 0.02g of dibutyltin dilaurate catalyst to the reactor, heat to 84℃ and react for 2.5h, add 0.44g of dimethylolpropionic acid and 0.8g of flame retardant chain extender, and continue to react for 2h to obtain polyurethane prepolymer, cool to 42℃, add 0.56g of pentaerythritol triacrylate to the polyurethane prepolymer, react for 1h, add 0.65g of dipentaerythritol hexaacrylate and 0.58g of dipropylene glycol diacrylate, stir for 1.5h, add 0.35g of triethylamine and 20mL of deionized water, stir for 40min to obtain modified polyurethane matrix;

[0039] (5) Dissolve 3.75 g of 2-bromo-5-hydroxypyridine and 6.2 g of pinacol diborate in 100 mL of 1,4-dioxane solvent, add 1.55 g of [1,1-bis(diphenylphosphine)ferrocene]palladium dichloride catalyst and 8.2 g of potassium carbonate, and react at 105 °C for 5 h under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the borate intermediate;

[0040] (6) Add 2.56 g of cyanuric chloride to 40 mL of toluene solvent and stir to dissolve. Dissolve 12.5 g of borate intermediate and 4.4 g of triethylamine acid retardant in 80 mL of toluene solvent. Add the solution dropwise at 100 °C for 50 min. After the addition is complete, react for 10 h. After the reaction is complete, filter and remove the solvent by rotary evaporation to obtain borate triazine flame retardant.

[0041] (7) Add 70 parts by weight of modified polyurethane matrix, 25 parts by weight of Ag@Fe3O4 conductive nanofiller, 0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone photoinitiator, and 8 parts by weight of borate triazine flame retardant to the reactor, stir and mix for 30 min to obtain an electronic adhesive containing nanomaterials for flexible circuit manufacturing.

[0042] Example 3

[0043] (1) 1g of Fe3O4 magnetic nanoparticles were immersed in 2.05mL of AgNO3 solution with a concentration of 0.5mol / L and reduced by electron beam irradiation to obtain Ag@Fe3O4 conductive nanofiller.

[0044] (2) Add 2.95 g of N-methyldiethanolamine to 70 mL of anhydrous ethanol solvent, stir to dissolve, add 5.2 g of 3-chloropropyltrimethoxysilane dropwise over 0.8 h, and after the addition is complete, heat to 79 °C and reflux for 16 h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate.

[0045] (3) Under a nitrogen atmosphere, 4.45 g of silane quaternary ammonium salt intermediate and 1 mL of triethylamine catalyst were added to 45 mL of dichloromethane solvent and stirred at 10 °C until dissolved. 1.67 g of phenylphosphodichloro was added dropwise over a period of 28 min. After the addition was complete, the reaction was carried out for 12 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain a flame-retardant chain extender.

[0046] (4) Add 3.5g of isophorone diisocyanate, 5g of polytetramethylene ether glycol, 0.3g of 1,4-butanediol, and 0.015g of dibutyltin dilaurate catalyst to the reactor, heat to 81℃ and react for 2h, add 0.4g of dimethylolpropionic acid and 0.775g of flame retardant chain extender, and continue to react for 1.5h to obtain polyurethane prepolymer, cool to 40℃, add 0.5g of pentaerythritol triacrylate to the polyurethane prepolymer, react for 0.8h, add 0.6g of dipentaerythritol hexaacrylate and 0.55g of dipropylene glycol diacrylate, stir for 1.2h, add 0.31g of triethylamine and 17.5mL of deionized water, stir for 30min to obtain modified polyurethane matrix;

[0047] (5) Dissolve 3.475 g of 2-bromo-5-hydroxypyridine and 6.1 g of pinacol diborate in 90 mL of 1,4-dioxane solvent, add 1.5 g of [1,1-bis(diphenylphosphine)ferrocene]palladium dichloride catalyst and 8.1 g of potassium carbonate, and react at 100 °C for 4 h under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the borate intermediate;

[0048] (6) Add 2.53 g of cyanuric chloride to 35 mL of toluene solvent and stir to dissolve. Dissolve 12.4 g of borate intermediate and 4.2 g of triethylamine acid retardant in 65 mL of toluene solvent. Add the solution dropwise at 95 °C for 45 min. After the addition is complete, react for 9 h. After the reaction is complete, filter and remove the solvent by rotary evaporation to obtain borate triazine flame retardant.

[0049] (7) Add 65 parts by weight of modified polyurethane matrix, 22.5 parts by weight of Ag@Fe3O4 conductive nanofiller, 0.4 parts by weight of 1-hydroxycyclohexylphenyl ketone photoinitiator, and 6 parts by weight of borate triazine flame retardant to the reactor, stir and mix for 25 min to obtain an electronic adhesive containing nanomaterials for flexible circuit manufacturing.

[0050] Example 4

[0051] (1) 0.8 g of Fe3O4 magnetic nanoparticles were immersed in 2 mL of AgNO3 solution with a concentration of 0.48 mol / L and reduced by electron beam irradiation to obtain Ag@Fe3O4 conductive nanofiller.

[0052] (2) Add 2.9 g of N-methyldiethanolamine to 60 mL of anhydrous ethanol solvent, stir to dissolve, add 5.1 g of 3-chloropropyltrimethoxysilane dropwise over a period of 0.5 h, and after the addition is complete, heat to 76 °C and reflux for 14 h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate.

[0053] (3) Under a nitrogen atmosphere, 4.4 g of silane quaternary ammonium salt intermediate and 0.8 mL of triethylamine catalyst were added to 40 mL of dichloromethane solvent and stirred at 8 °C until dissolved. 1.62 g of phenylphosphodichloro was added dropwise over a period of 20 min. After the addition was complete, the reaction was carried out for 10 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain a flame-retardant chain extender.

[0054] (4) Add 3.55g of isophorone diisocyanate, 5.2g of polytetramethylene ether glycol, 0.32g of 1,4-butanediol, and 0.02g of dibutyltin dilaurate catalyst to the reactor, heat to 84℃ and react for 2.5h, add 0.44g of dimethylolpropionic acid and 0.8g of flame retardant chain extender, and continue to react for 2h to obtain polyurethane prepolymer, cool to 42℃, add 0.56g of pentaerythritol triacrylate to the polyurethane prepolymer, react for 1h, add 0.65g of dipentaerythritol hexaacrylate and 0.58g of dipropylene glycol diacrylate, stir for 1.5h, add 0.35g of triethylamine and 20mL of deionized water, stir for 40min to obtain modified polyurethane matrix;

[0055] (5) Dissolve 3.75 g of 2-bromo-5-hydroxypyridine and 6.2 g of pinacol diborate in 100 mL of 1,4-dioxane solvent, add 1.55 g of [1,1-bis(diphenylphosphine)ferrocene]palladium dichloride catalyst and 8.2 g of potassium carbonate, and react at 105 °C for 5 h under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the borate intermediate;

[0056] (6) Add 2.53 g of cyanuric chloride to 35 mL of toluene solvent and stir to dissolve. Dissolve 12.4 g of borate intermediate and 4.2 g of triethylamine acid retardant in 65 mL of toluene solvent. Add the solution dropwise at 95 °C for 45 min. After the addition is complete, react for 9 h. After the reaction is complete, filter and remove the solvent by rotary evaporation to obtain borate triazine flame retardant.

[0057] (7) Add 65 parts by weight of modified polyurethane matrix, 22.5 parts by weight of Ag@Fe3O4 conductive nanofiller, 0.4 parts by weight of 1-hydroxycyclohexylphenyl ketone photoinitiator, and 6 parts by weight of borate triazine flame retardant to the reactor, stir and mix for 25 min to obtain an electronic adhesive containing nanomaterials for flexible circuit manufacturing.

[0058] Example 5

[0059] (1) 1.2 g of Fe3O4 magnetic nanoparticles were immersed in 2.1 mL of AgNO3 solution with a concentration of 0.52 mol / L and reduced by electron beam irradiation to obtain Ag@Fe3O4 conductive nanofiller.

[0060] (2) Add 3g of N-methyldiethanolamine to 80mL of anhydrous ethanol solvent, stir to dissolve, add 5.3g of 3-chloropropyltrimethoxysilane dropwise over 1h, and after the addition is complete, heat to 82℃ and reflux for 18h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate.

[0061] (3) Under a nitrogen atmosphere, 4.5 g of silane quaternary ammonium salt intermediate and 1.2 mL of triethylamine catalyst were added to 50 mL of dichloromethane solvent and stirred at 12 °C until dissolved. 1.72 g of phenylphosphodichloro was added dropwise over a period of 35 min. After the addition was complete, the reaction was carried out for 14 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain a flame-retardant chain extender.

[0062] (4) Add 3.5g of isophorone diisocyanate, 5g of polytetramethylene ether glycol, 0.3g of 1,4-butanediol, and 0.015g of dibutyltin dilaurate catalyst to the reactor, heat to 81℃ and react for 2h, add 0.4g of dimethylolpropionic acid and 0.775g of flame retardant chain extender, and continue to react for 1.5h to obtain polyurethane prepolymer, cool to 40℃, add 0.5g of pentaerythritol triacrylate to the polyurethane prepolymer, react for 0.8h, add 0.6g of dipentaerythritol hexaacrylate and 0.55g of dipropylene glycol diacrylate, stir for 1.2h, add 0.31g of triethylamine and 17.5mL of deionized water, stir for 30min to obtain modified polyurethane matrix;

[0063] (5) Dissolve 3.475 g of 2-bromo-5-hydroxypyridine and 6.1 g of pinacol diborate in 90 mL of 1,4-dioxane solvent, add 1.5 g of [1,1-bis(diphenylphosphine)ferrocene]palladium dichloride catalyst and 8.1 g of potassium carbonate, and react at 100 °C for 4 h under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the borate intermediate;

[0064] (6) Add 2.5g of cyanuric chloride to 30mL of toluene solvent and stir to dissolve. Dissolve 12.3g of borate intermediate and 4g of triethylamine acid retardant in 50mL of toluene solvent. Add the solution dropwise at 90℃ for 40min. After the addition is complete, react for 8h. After the reaction is complete, filter and remove the solvent by rotary evaporation to obtain borate triazine flame retardant.

[0065] (7) Add 60 parts by weight of modified polyurethane matrix, 20 parts by weight of Ag@Fe3O4 conductive nanofiller, 0.2 parts by weight of 1-hydroxycyclohexylphenyl ketone photoinitiator, and 4 parts by weight of borate triazine flame retardant to the reactor, stir and mix for 20 min to obtain an electronic adhesive containing nanomaterials for flexible circuit manufacturing.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 5 is that step (4) does not contain a flame-retardant chain extender.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 5 is that step (7) does not contain borate triazine flame retardant.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 5 is that in step (7), the Ag@Fe3O4 conductive nanofiller is replaced with nano silver powder.

[0072] The electronic adhesives from Examples 1-5 and Comparative Examples 1-3 were coated onto PET films and cured in an ultraviolet curing machine for 4 minutes.

[0073] The flame retardant performance was tested according to the UL94 flammability test method, and the test results are shown in Table 1.

[0074] Table 1: Flame retardant performance test.

[0075] project Flame retardant rating Example 1 UL94-V0 Example 2 UL94-V0 Example 3 UL94-V0 Example 4 UL94-V0 Example 5 UL94-V0 Comparative Example 1 UL94-V1 Comparative Example 2 UL94-V1 Comparative Example 3 UL94-V0

[0076] As shown in Table 1, the electronic adhesives in Examples 1-5 and Comparative Example 3 of the present invention have better flame retardant effects compared with the electronic adhesives in Comparative Examples 1-2.

[0077] The conductivity was tested using an ST2253 digital four-probe resistance tester, and the test results are shown in Table 2.

[0078] Table 2: Conductivity test.

[0079]

[0080]

[0081] As shown in Table 2, the electronic adhesives in Examples 1-5 and Comparative Examples 1-2 of the present invention have lower resistivity and better conductivity compared to the electronic adhesive in Comparative Example 3.

[0082] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0083] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0084] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. An electronic adhesive containing nanomaterials for flexible circuit fabrication, characterized in that, It includes the following components by weight: 60-70 parts by weight of modified polyurethane matrix, 20-25 parts by weight of Ag@Fe3O4 conductive nanofiller, 0.2-0.6 parts by weight of 1-hydroxycyclohexylphenyl ketone photoinitiator, and 4-8 parts by weight of borate triazine flame retardant.

2. The electronic adhesive containing nanomaterials for flexible circuit manufacturing according to claim 1, characterized in that, The preparation method of the Ag@Fe3O4 conductive nanofiller is as follows: 0.8-1.2g of Fe3O4 magnetic nanoparticles are impregnated in 2-2.1mL of AgNO3 solution with a concentration of 0.48-0.52mol / L, and reduced by electron beam irradiation to obtain Ag@Fe3O4 conductive nanofiller.

3. The electronic adhesive containing nanomaterials for flexible circuit manufacturing according to claim 1, characterized in that, The method for preparing the modified polyurethane matrix includes the following steps: (1) Add 2.9-3g of N-methyldiethanolamine to 60-80mL of anhydrous ethanol solvent, stir to dissolve, and add 5.1-5.3g of 3-chloropropyltrimethoxysilane dropwise. After the addition is complete, heat to 76-82℃ and reflux for 14-18h. After the reaction is complete, remove the solvent by rotary evaporation to obtain the silane quaternary ammonium salt intermediate. (2) Under a nitrogen atmosphere, 4.4-4.5 g of silane quaternary ammonium salt intermediate and 0.8-1.2 mL of triethylamine catalyst were added to 40-50 mL of dichloromethane solvent and stirred at 8-12 °C until dissolved. 1.62-1.72 g of phenylphosphodichloro was added dropwise over a period of 20-35 min. After the addition was complete, the reaction was allowed to proceed for 10-14 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the product was washed and dried under vacuum to obtain a flame-retardant chain extender. (3) Add 3.45-3.55g of isophorone diisocyanate, 4.8-5.2g of polytetramethylene ether glycol, 0.28-0.32g of 1,4-butanediol, and 0.01-0.02g of dibutyltin dilaurate catalyst to the reactor, heat to 78-84℃ and react for 1.5-2.5h, then add 0.36-0.44g of dimethylolpropionic acid and 0.75-0.8g of flame-retardant chain extender, and continue the reaction for 1-2h to obtain polyurethane. The ester prepolymer was cooled to 38-42℃, and 0.44-0.56g of pentaerythritol triacrylate was added to the polyurethane prepolymer. After reacting for 0.5-1h, 0.55-0.65g of dipentaerythritol hexaacrylate and 0.52-0.58g of dipropylene glycol diacrylate were added, and the mixture was stirred for 1-1.5h. Then, 0.27-0.35g of triethylamine and 15-20mL of deionized water were added, and the mixture was stirred for 20-40min to obtain the modified polyurethane matrix.

4. The electronic adhesive containing nanomaterials for flexible circuit manufacturing according to claim 3, characterized in that, In step (1), the 3-chloropropyltrimethoxysilane is added over a period of 0.5-1 h.

5. The electronic adhesive containing nanomaterials for flexible circuit manufacturing according to claim 1, characterized in that, The preparation method of the borate triazine flame retardant includes the following steps: S1. Dissolve 3.2-3.75 g of 2-bromo-5-hydroxypyridine and 6-6.2 g of pinacol diboronic acid ester in 80-100 mL of 1,4-dioxane solvent, add 1.45-1.55 g of catalyst and 8-8.2 g of potassium carbonate, and react at 95-105 °C for 3-5 h under a nitrogen atmosphere. After the reaction is completed, remove the solvent by rotary evaporation, wash and vacuum dry to obtain the borate ester intermediate. S2. Add 2.5-2.56 g of cyanuric chloride to 30-40 mL of toluene solvent and stir to dissolve. Dissolve 12.3-12.5 g of borate intermediate and 4-4.4 g of triethylamine acid retardant in 50-80 mL of toluene solvent. At the reaction temperature, add the solution dropwise to the cyanuric chloride solution over a period of 40-50 min. After the addition is complete, allow the reaction to proceed for 8-10 h. After the reaction is complete, filter the solution and remove the solvent by rotary evaporation to obtain the borate triazine flame retardant.

6. The electronic adhesive containing nanomaterials for flexible circuit fabrication according to claim 5, characterized in that, The catalyst in S1 is [1,1-bis(diphenylphosphine)ferrocene]palladium dichloride.

7. The electronic adhesive containing nanomaterials for flexible circuit fabrication according to claim 5, characterized in that, The reaction temperature in S2 is 90-100℃.

8. A method for preparing an electronic adhesive containing nanomaterials for flexible circuit fabrication as described in any one of claims 1-7, characterized in that, The preparation method of the electronic adhesive containing nanomaterials for flexible circuit manufacturing is as follows: add modified polyurethane matrix, Ag@Fe3O4 conductive nanofiller, 1-hydroxycyclohexylphenyl ketone photoinitiator, and borate triazine flame retardant to a reactor, stir and mix for 20-30 minutes to obtain the electronic adhesive containing nanomaterials for flexible circuit manufacturing.

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