High-strength low-resistance adhesive tape for internal precision connection of electronic product

Abstract

The invention relates to the technical field of conductive adhesive tapes, and provides a high-strength low-resistance adhesive tape for internal precision connection of electronic products, which comprises a base material layer and an adhesive layer arranged on the surface of the base material layer in sequence, the adhesive layer is prepared from the following raw materials in parts by weight: 40 to 70 parts of acrylate adhesive, 30 to 60 parts of lignin-based adhesive, 15 to 30 parts of graphene-lignin polymer composite material, 5 to 15 parts of maleic anhydride, 2 to 10 parts of conductive particles, 5 to 15 parts of cross-linking agent and 2 to 10 parts of initiator. Through coordination and cooperation of multiple functional components, the obtained adhesive tape has the advantages of low resistance, high adhesive force and high mechanical strength, and meets the performance requirements of internal precision connection of electronic products.

Description

Technical Field

[0001] This invention relates to the field of conductive tape technology, and in particular to a high-strength, low-resistance tape for precision internal connections in electronic products. Background Technology

[0002] Conductive tape is widely used in electronic products. Traditional circuit boards contain many circuits, and some areas are unsuitable for soldering, requiring conductive tape to connect and ground them. Some electronic components require electromagnetic shielding to eliminate electrical signal interference, necessitating the physical shielding provided by conductive tape. Some precision components are susceptible to static electricity interference, requiring conductive tape for static discharge. Conductive tape was developed to address these needs, serving functions such as electromagnetic shielding, static electricity conduction (static discharge), circuit grounding, and sealing of gaps.

[0003] Existing conductive tapes use a large amount of conductive material, have high resistance, low strength, and insufficient adhesion, and are prone to residue and peeling / curling, thus failing to meet the requirements of various conductive substrates. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a high-strength, low-resistance adhesive tape for precision internal connections in electronic products.

[0005] The technical solution of the present invention is as follows:

[0006] This invention provides a high-strength, low-resistance adhesive tape for precision internal connections in electronic products, comprising a substrate layer and an adhesive layer disposed on the surface of the substrate layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 40-70 parts of acrylic adhesive, 30-60 parts of lignin-based adhesive, 15-30 parts of graphene-lignin polymer composite material, 5-15 parts of maleic anhydride, 2-10 parts of conductive particles, 5-15 parts of crosslinking agent, and 2-10 parts of initiator;

[0007] The lignin-based adhesive is obtained by reacting lignin with polyvinyl alcohol;

[0008] The preparation method of the graphene-lignin polymer composite material includes the following steps:

[0009] S1. Graphene oxide is dispersed in water, a surfactant is added, and the mixture is ultrasonically treated for a period of time. The graphene oxide is then separated by filtration. The treated graphene oxide is dispersed in a eutectic solvent, stirred for a period of time, washed with ethanol, and separated by filtration to obtain pretreated graphene.

[0010] S2. Lignin is dissolved in NaOH solution to obtain a lignin solution. Ammonia water is added to silver nitrate aqueous solution to obtain [Ag(NH3)2]. +Complex solution; lignin solution is added dropwise to [Ag(NH3)2] + The complex solution was stirred and reacted in the dark for a period of time, then dialyzed and freeze-dried to obtain lignin / silver nanoparticles;

[0011] S3. Disperse phosphorus-containing polymer, pretreated graphene, and lignin / silver nanoparticles in a solution of conductive monomers, add an initiator, and carry out in-situ polymerization at room temperature to obtain graphene-lignin polymer composite material.

[0012] Lignin-based adhesives, obtained by reacting lignin with polyvinyl alcohol (PVA), are environmentally friendly and sustainable adhesives that combine the natural adhesive properties of lignin with the film-forming properties and mechanical strength of PVA, resulting in excellent bonding performance and mechanical strength. In graphene-lignin polymer composites, graphene exhibits excellent electrical conductivity. First, a surfactant is used to modify the graphene surface, enhancing its reactivity. Then, a eutectic solvent is applied to further modify the graphene surface. This solvent forms a stable interfacial layer on the graphene surface, effectively preventing graphene aggregation and enhancing the compatibility and dispersibility between graphene and the polymer, thus achieving uniform dispersion in the composite. Lignin / silver nanoparticles improve the adhesion of the composite. Lignin is a promising raw material for adhesive preparation. Under the influence of silver, a dynamic quinone-catechol structure forms on the lignin surface, promoting polymerization and imparting long-lasting adhesion to the graphene-lignin polymer composite. Silver's excellent electrical conductivity reduces the resistance of the adhesive tape. Phosphorus-containing polymers improve the flame retardancy, water resistance, and heat resistance of the adhesive, thereby maintaining stable adhesive performance. The composite material obtained by reacting phosphorus-containing polymers, pretreated graphene, lignin / silver nanoparticles, and conductive monomers combines the characteristics of each component and significantly improves its electrical conductivity and adhesion. Acrylic adhesives offer rapid drying and molding, good transparency, excellent adhesion to various materials, and strong weather resistance. Maleic anhydride, through reaction with hydroxyl or amine groups in other components, forms a cross-linked network structure, increasing the adhesive's tack and strength, thus improving its bonding performance and durability. This invention, through the synergistic combination of multiple functional components, results in an adhesive tape with low resistance, high adhesion, and high mechanical strength, meeting the performance requirements of precision internal connections in electronic products.

[0013] Preferably, the method for preparing the lignin-based adhesive includes the following steps:

[0014] 1) Add polyphenols to an ionic liquid and stir to dissolve them, thus obtaining a polyphenol-ionic liquid;

[0015] 2) Add lignin to the polyphenol-ionic liquid and sonicate it at 40-70℃ to dissolve it, thus obtaining a mixed solution;

[0016] 3) Continue heating the mixture to 80-100℃, add polyvinyl alcohol and succinic anhydride, stir and react for a period of time to obtain lignin-based adhesive.

[0017] The lignin-based adhesive provided by this invention first utilizes ionic liquids to dissolve and enhance the subsequent reaction performance of lignin. Polyphenols contain phenolic hydroxyl groups, polyvinyl alcohol (PVA) contains hydroxyl groups, and lignin contains hydroxyl, phenolic hydroxyl, and carboxyl groups. Succinic anhydride is modified by esterification with some hydroxyl groups on the polyvinyl alcohol and lignin molecular chains, followed by crosslinking via esterification with polyvinyl alcohol through carboxyl groups. Simultaneously, numerous hydroxyl groups on the polyvinyl alcohol molecular chains generate strong intermolecular and intramolecular hydrogen bonds with the hydroxyl and carboxyl groups on the lignin molecules and the phenolic hydroxyl groups on the polyphenol molecules, resulting in a crosslinking reaction. These multiple crosslinking reactions form a crosslinked network with a three-dimensional spatial structure. This invention yields a crosslinked lignin-based adhesive with high mechanical strength and high adhesion performance, meeting the performance requirements of fields such as electronic device adhesion. The preparation process of this invention is simple to operate and environmentally friendly.

[0018] Preferably, in step 1):

[0019] Polyphenols include at least one of quercetin, tannic acid, dopamine, catechol, gallic acid, and epigallocatechin gallate.

[0020] Ionic liquids include at least one of 1-ethyl-3-methylimidazolium acetate, alanine cholate, glycine cholate, lysine cholate, and threonine cholate.

[0021] The mass ratio of polyphenols to ionic liquids is 1:(1-10).

[0022] Preferably, in step 2):

[0023] Lignin includes at least one of sulfonated lignin, hydroxylated lignin, carboxylated lignin, and alkali lignin;

[0024] The mass ratio of polyphenols to lignin is 1:(2-5);

[0025] The ultrasound frequency is 20–30 kHz, and the duration is 10–30 min.

[0026] Preferably, in step 3):

[0027] The mass ratio of polyvinyl alcohol, succinic anhydride and lignin is (1-5):(1-5):(2-10);

[0028] The stirring reaction time is 5 to 10 hours.

[0029] Preferably, in step S1:

[0030] Surfactants include at least one of polyvinyl alcohol, polyethylene glycol, sodium lignosulfonate, polyvinylpyrrolidone (PVP), or sodium dodecylbenzenesulfonate;

[0031] The amount of surfactant used is 2 to 10 wt% of the mass of graphene oxide;

[0032] Eutectic solvents include one of the following: choline chloride-urea eutectic solvents and choline chloride-lactic acid eutectic solvents;

[0033] The amount of eutectic solvent used is 1 to 10 times the mass of graphene oxide.

[0034] The frequency of ultrasonic treatment is 20–30 kHz, and the duration is 10–30 min;

[0035] The stirring temperature is 20–30℃, and the processing time is 8–10 hours.

[0036] Preferably, in step S2:

[0037] Lignin solution and [Ag(NH3)2] + In the complex solution, lignin reacts with [Ag(NH3)2]. + The mass ratio of the complex is (1-3):1;

[0038] The temperature for the stirred reaction is 20–40℃, and the time is 12–24 h;

[0039] Preferably, in step S3:

[0040] The mass ratio of phosphorus-containing polymer, pretreated graphene, lignin / silver nanoparticles and conductive monomer is (1-2):(2-5):(5-10):(1-3);

[0041] Conductive monomers include at least one of styrene and pyrrole;

[0042] Initiators include at least one of ammonium persulfate, potassium persulfate, and sodium persulfate;

[0043] The amount of initiator used is 1 to 10 wt% of the mass of the conductive monomer.

[0044] Preferably, in step S3:

[0045] Phosphorus-containing polymers include at least one of sodium polyphosphate and phytic acid;

[0046] Preferably, the raw materials of the adhesive layer include:

[0047] The conductive particles include at least one of carbon nanotubes, graphene, zinc oxide, aluminum powder, magnesium powder, tin powder, and copper powder.

[0048] The crosslinking agent includes at least one of benzamide peroxide, dicumyl peroxide, di-tert-butyl peroxide, and dicumyl peroxide.

[0049] The initiator includes at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0050] Preferably, the method for preparing the adhesive layer includes: mixing the raw materials of the adhesive layer evenly, heating to 80-100°C, and maintaining for 10-30 minutes.

[0051] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0052] 1. The lignin-based adhesive obtained by reacting lignin with polyvinyl alcohol (PVA) is an environmentally friendly and sustainable adhesive that combines the natural adhesive properties of lignin with the film-forming properties and mechanical strength of PVA, and has good adhesive performance and mechanical strength. In graphene-lignin polymer composites, graphene exhibits excellent electrical conductivity. First, a surfactant is used to modify the graphene surface, enhancing its reactivity. Then, a eutectic solvent is applied to further modify the graphene surface. This solvent forms a stable interfacial layer on the graphene surface, effectively preventing graphene aggregation and enhancing the compatibility and dispersibility between graphene and the polymer, thus achieving uniform dispersion in the composite. Lignin / silver nanoparticles improve the adhesion of the composite. Lignin is a promising raw material for adhesive preparation. Under the influence of silver, a dynamic quinone-catechol structure forms on the lignin surface, promoting polymerization and imparting long-lasting adhesion to the graphene-lignin polymer composite. Silver's excellent electrical conductivity reduces the resistance of the adhesive tape. Phosphorus-containing polymers improve the flame retardancy, water resistance, and heat resistance of the adhesive, thereby maintaining stable adhesive performance. The composite material obtained by reacting phosphorus-containing polymers, pretreated graphene, lignin / silver nanoparticles, and conductive monomers combines the characteristics of each component and significantly improves its electrical conductivity and adhesion. Acrylic adhesives offer rapid drying and molding, good transparency, excellent adhesion to various materials, and strong weather resistance. Maleic anhydride, through reaction with hydroxyl or amine groups in other components, forms a cross-linked network structure, increasing the adhesive's tack and strength, thus improving its bonding performance and durability. This invention, through the synergistic combination of multiple functional components, results in an adhesive tape with low resistance, high adhesion, and high mechanical strength, meeting the performance requirements of precision internal connections in electronic products.

[0053] 2. The lignin-based adhesive provided by this invention first utilizes ionic liquids to dissolve and enhance the subsequent reaction performance of lignin. Polyphenols contain phenolic hydroxyl groups, polyvinyl alcohol (PVA) contains hydroxyl groups, and lignin contains hydroxyl, phenolic hydroxyl, and carboxyl groups. Succinic anhydride is modified by esterification with some hydroxyl groups on the polyvinyl alcohol and lignin molecular chains, and then crosslinks with polyvinyl alcohol through esterification via carboxyl groups. Simultaneously, a large number of hydroxyl groups on the polyvinyl alcohol molecular chain generate strong intermolecular and intramolecular hydrogen bonds with the hydroxyl and carboxyl groups on the lignin molecules and the phenolic hydroxyl groups on the polyphenol molecules, thereby undergoing a crosslinking reaction. Multiple crosslinking reactions form a crosslinked network with a three-dimensional spatial structure. This invention yields a crosslinked lignin-based adhesive with high mechanical strength and high adhesion performance to meet the performance requirements of fields such as electronic device adhesion. The preparation process of this invention is simple to operate and environmentally friendly. Detailed Implementation

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] In the preferred embodiments of this invention, all equipment and reagents are commercially available.

[0056] Example 1

[0057] A high-strength, low-resistance adhesive tape for precision internal connections in electronic products includes a substrate layer and an adhesive layer disposed on the surface of the substrate layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 70 parts of acrylic adhesive, 30 parts of lignin-based adhesive, 15 parts of graphene-lignin polymer composite material, 5 parts of maleic anhydride, 2 parts of carbon nanotubes, 5 parts of benzamide peroxide crosslinking agent, and 2 parts of ammonium persulfate initiator.

[0058] The method for preparing the adhesive layer includes the following steps:

[0059] 1. Preparation of graphene-lignin polymer composite materials:

[0060] S1. Graphene oxide was dispersed in water, and 2 wt% polyvinyl alcohol surfactant was added. The mixture was ultrasonically treated at a frequency of 20 kHz for 30 min, and the graphene oxide was separated by filtration. The treated graphene oxide was dispersed in a eutectic solvent of choline chloride and urea (the amount of which was 10 times the mass of the graphene oxide, and the molar ratio of choline chloride to urea was 1:2), stirred at 20 °C for 10 h, washed with ethanol, and filtered to obtain pretreated graphene.

[0061] S2. Sulfonated lignin is dissolved in NaOH solution to obtain a lignin solution. Ammonia water is added to silver nitrate aqueous solution to obtain [Ag(NH3)2]. + Complex solution; lignin solution is added dropwise to [Ag(NH3)2] + In the complex solution, lignin reacts with [Ag(NH3)2]. + The complex was reacted at a mass ratio of 1:1 at 20°C for 24 hours under light-protected conditions, followed by dialyzing and freeze-drying to obtain lignin / silver nanoparticles.

[0062] S3. Sodium polyphosphate, pretreated graphene, and lignin / silver nanoparticles are dispersed in a styrene DMF solution. The mass ratio of sodium polyphosphate, pretreated graphene, lignin / silver nanoparticles to conductive monomers is 2:5:10:3. 2 wt% of ammonium persulfate initiator is added to styrene, and in-situ polymerization is carried out at room temperature to obtain a graphene-lignin polymer composite material.

[0063] 2. Preparation of lignin-based adhesives:

[0064] 1) Add tannic acid to 1-ethyl-3-methylimidazolium acetate (the mass ratio of tannic acid to 1-ethyl-3-methylimidazolium acetate is 1:1.5), stir to dissolve, and obtain polyphenol-ionic liquid;

[0065] 2) Add sulfonated lignin to polyphenol-ionic liquid, with a mass ratio of polyphenol to lignin of 1:2, and sonicate at 40°C for 30 min to dissolve it, obtaining a mixed solution.

[0066] 3) Continue heating until the mixed solution reaches 80℃, then add polyvinyl alcohol and succinic anhydride. The mass ratio of polyvinyl alcohol, succinic anhydride, and lignin is 5:1:10. Stir and react for 5 hours to obtain a lignin-based adhesive.

[0067] 3. Mix the raw materials of the adhesive layer evenly according to the weight proportions, heat to 80℃, and maintain for 30 minutes to obtain the adhesive layer.

[0068] Example 2

[0069] A high-strength, low-resistance adhesive tape for precision internal connections in electronic products includes a substrate layer and an adhesive layer disposed on the surface of the substrate layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 40 parts of acrylic adhesive, 60 parts of lignin-based adhesive, 30 parts of graphene-lignin polymer composite material, 15 parts of maleic anhydride, 5 parts of graphene, 10 parts of copper powder, 15 parts of dicumyl peroxide crosslinking agent, and 10 parts of sodium persulfate initiator.

[0070] The method for preparing the adhesive layer includes the following steps:

[0071] 1. Preparation of graphene-lignin polymer composite materials:

[0072] S1. Graphene oxide was dispersed in water, and sodium dodecylbenzenesulfonate surfactant (10 wt% of the graphene oxide mass) was added. The mixture was ultrasonically treated at a frequency of 30 kHz for 10 min, and the graphene oxide was separated by filtration. The treated graphene oxide was dispersed in a eutectic solvent of choline chloride and lactic acid (1.5 times the mass of graphene oxide, with a molar ratio of choline chloride to lactic acid of 1:2), stirred at 30 °C for 8 h, washed with ethanol, and filtered to obtain pretreated graphene.

[0073] S2. Hydroxylated lignin is dissolved in NaOH solution to obtain a lignin solution. Ammonia water is added to silver nitrate aqueous solution to obtain [Ag(NH3)2]. + Complex solution; lignin solution is added dropwise to [Ag(NH3)2] + In the complex solution, lignin reacts with [Ag(NH3)2]. + The complex was reacted at a mass ratio of 3:1, stirred at 40°C for 12 h under light-protected conditions, then dialyzed and freeze-dried to obtain lignin / silver nanoparticles.

[0074] S3. Sodium polyphosphate, pretreated graphene, and lignin / silver nanoparticles are dispersed in a DMF solution of pyrrole. The mass ratio of sodium polyphosphate, pretreated graphene, lignin / silver nanoparticles to pyrrole is 1:2:5:3. Sodium persulfate initiator of 10 wt% of pyrrole is added, and in-situ polymerization is carried out at room temperature to obtain a graphene-lignin polymer composite material.

[0075] 2. Preparation of lignin-based adhesives:

[0076] 1) Add quercetin to alanine choline salt at a mass ratio of 1:10 and stir to dissolve, thus obtaining a polyphenol-ionic liquid.

[0077] 2) Add hydroxylated lignin to polyphenol-ionic liquid, with a mass ratio of polyphenol to lignin of 1:5, and sonicate at 70°C for 10 min to dissolve it, obtaining a mixed solution.

[0078] 3) Continue heating until the temperature of the mixed solution reaches 100℃, then add polyvinyl alcohol and succinic anhydride. The mass ratio of polyvinyl alcohol, succinic anhydride and lignin is 1:1:2. Stir and react for 5 hours to obtain lignin-based adhesive.

[0079] 3. Mix the raw materials of the adhesive layer evenly according to the weight proportions, heat to 100℃, and maintain for 10 minutes to obtain the adhesive layer.

[0080] Example 3

[0081] A high-strength, low-resistance adhesive tape for precision internal connections in electronic products includes a substrate layer and an adhesive layer disposed on the surface of the substrate layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 60 parts of acrylic adhesive, 40 parts of lignin-based adhesive, 20 parts of graphene-lignin polymer composite material, 10 parts of maleic anhydride, 4 parts of zinc oxide, 2 parts of aluminum powder, 2 parts of tin powder, 10 parts of di-tert-butyl peroxide crosslinking agent, and 5 parts of potassium persulfate initiator.

[0082] The method for preparing the adhesive layer includes the following steps:

[0083] 1. Preparation of graphene-lignin polymer composite materials:

[0084] S1. Graphene oxide was dispersed in water, and 4.5 wt% polyvinylpyrrolidone surfactant was added. The mixture was ultrasonically treated at a frequency of 25 kHz for 15 min, and the graphene oxide was separated by filtration. The treated graphene oxide was dispersed in a eutectic solvent of choline chloride and lactic acid (the amount of which was 3 times the mass of the graphene oxide, and the molar ratio of choline chloride to lactic acid was 1:2), stirred at 25 °C for 8 h, washed with ethanol, and filtered to obtain pretreated graphene.

[0085] S2. Dissolve carboxylated lignin in NaOH solution to obtain a lignin solution. Add ammonia water to silver nitrate aqueous solution to obtain [Ag(NH3)2]. + Complex solution; lignin solution is added dropwise to [Ag(NH3)2] + In the complex solution, lignin reacts with [Ag(NH3)2]. + The mass ratio of the complex was 2.5:1. The reaction was carried out at 30°C for 15 hours under light-protected conditions with stirring. Then, the mixture was dialyzed and freeze-dried to obtain lignin / silver nanoparticles.

[0086] S3. Phytic acid, pretreated graphene, and lignin / silver nanoparticles are dispersed in a DMF solution of pyrrole. The mass ratio of phytic acid, pretreated graphene, lignin / silver nanoparticles to pyrrole is 3:8:15:5. 3.5 wt% of potassium persulfate initiator is added to the pyrrole, and in-situ polymerization is carried out at room temperature to obtain a graphene-lignin polymer composite material.

[0087] 2. Preparation of lignin-based adhesives:

[0088] 1) Add dopamine to glycine choline salt at a mass ratio of 1:8 and stir to dissolve to obtain a polyphenol-ionic liquid.

[0089] 2) Add alkali lignin to polyphenol-ionic liquid, with a mass ratio of polyphenol to alkali lignin of 1:3, and sonicate at 50°C for 15 min to dissolve it, obtaining a mixed solution.

[0090] 3) Continue heating until the temperature of the mixed solution reaches 90℃, then add polyvinyl alcohol and succinic anhydride. The mass ratio of polyvinyl alcohol, succinic anhydride and lignin is 3:2:8. Stir and react for 8 hours to obtain lignin-based adhesive.

[0091] 3. Mix the raw materials of the adhesive layer evenly according to the weight proportions, heat to 90℃, and maintain for 15 minutes to obtain the adhesive layer.

[0092] Example 4

[0093] A high-strength, low-resistance adhesive tape for precision internal connections in electronic products includes a substrate layer and an adhesive layer disposed on the surface of the substrate layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 50 parts of acrylic adhesive, 50 parts of lignin-based adhesive, 25 parts of graphene-lignin polymer composite material, 7.5 parts of maleic anhydride, 2 parts of graphene, 2 parts of magnesium powder, 7 parts of crosslinking agent, and 8 parts of potassium persulfate initiator.

[0094] The method for preparing the adhesive layer includes the following steps:

[0095] 1. Preparation of graphene-lignin polymer composite materials:

[0096] S1. Graphene oxide was dispersed in water, and sodium lignosulfonate surfactant (8 wt% of the graphene oxide mass) was added. The mixture was ultrasonically treated at 25 kHz for 20 min, and the graphene oxide was separated by filtration. The treated graphene oxide was dispersed in a eutectic solvent of choline chloride and urea (7 times the mass of graphene oxide, with a molar ratio of choline chloride to urea of ​​1:2), stirred at 25 °C for 9 h, washed with ethanol, and filtered to obtain pretreated graphene.

[0097] S2. Dissolve alkali lignin in NaOH solution to obtain lignin solution. Add ammonia water to silver nitrate aqueous solution to obtain [Ag(NH3)2]. + Complex solution; lignin solution is added dropwise to [Ag(NH3)2] + In the complex solution, lignin reacts with [Ag(NH3)2]. + The mass ratio of the complex was 2.5:1. The reaction was carried out at 30°C for 18 hours under light-protected conditions with stirring. Then, the mixture was dialyzed and freeze-dried to obtain lignin / silver nanoparticles.

[0098] S3. Phytic acid, pretreated graphene, and lignin / silver nanoparticles are dispersed in a styrene DMF solution. The mass ratio of phytic acid, pretreated graphene, lignin / silver nanoparticles to styrene is 3:6:10:3. 3.5 wt% of potassium persulfate initiator is added to styrene, and in-situ polymerization is carried out at room temperature to obtain a graphene-lignin polymer composite material.

[0099] 2. Preparation of lignin-based adhesives:

[0100] 1) Add catechins to lysine cholates at a mass ratio of 1:5 and stir to dissolve them to obtain a polyphenol-ionic liquid.

[0101] 2) Add alkali lignin to polyphenol-ionic liquid, with a mass ratio of catechol to alkali lignin of 1:4, and sonicate at 60°C for 20 min to dissolve it, obtaining a mixed solution.

[0102] 3) Continue heating until the temperature of the mixed solution reaches 85℃, then add polyvinyl alcohol and succinic anhydride. The mass ratio of polyvinyl alcohol, succinic anhydride and lignin is 4:2:7. Stir and react for 7 hours to obtain lignin-based adhesive.

[0103] 3. Mix the raw materials of the adhesive layer evenly according to the weight proportions, heat to 95℃, and maintain for 15 minutes to obtain the adhesive layer.

[0104] Example 5

[0105] A high-strength, low-resistance adhesive tape for precision internal connections in electronic products includes a substrate layer and an adhesive layer disposed on the surface of the substrate layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 55 parts acrylate adhesive, 45 parts lignin-based adhesive, 22 parts graphene-lignin polymer composite material, 12 parts maleic anhydride, 2 parts carbon nanotubes, 2 parts zinc oxide, 2 parts tin powder, 8 parts dicumyl peroxide crosslinking agent, and 6 parts ammonium persulfate initiator.

[0106] The method for preparing the adhesive layer includes the following steps:

[0107] 1. Preparation of graphene-lignin polymer composite materials:

[0108] S1. Graphene oxide was dispersed in water, and 6.5 wt% polyethylene glycol surfactant was added. The mixture was ultrasonically treated at a frequency of 25 kHz for 15 min, and the graphene oxide was separated by filtration. The treated graphene oxide was dispersed in a eutectic solvent of choline chloride and urea (the amount of which was 5 times the mass of the graphene oxide, and the molar ratio of choline chloride to urea was 1:2), stirred at 25 °C for 9 h, washed with ethanol, and filtered to obtain pretreated graphene.

[0109] S2. Hydroxylated lignin is dissolved in NaOH solution to obtain a lignin solution. Ammonia water is added to silver nitrate aqueous solution to obtain [Ag(NH3)2]. + Complex solution; lignin solution is added dropwise to [Ag(NH3)2] + In the complex solution, lignin reacts with [Ag(NH3)2]. + The mass ratio of the complex was 2:1. The reaction was carried out at 30°C for 18 hours under light-protected conditions with stirring. Then, the mixture was dialyzed and freeze-dried to obtain lignin / silver nanoparticles.

[0110] S3. Phytic acid, pretreated graphene, and lignin / silver nanoparticles are dispersed in a DMF solution of pyrrole. The mass ratio of phytic acid, pretreated graphene, lignin / silver nanoparticles to pyrrole is 3:7:15:4. Ammonium persulfate initiator of 5 wt% of pyrrole is added, and in-situ polymerization reaction is carried out at room temperature to obtain graphene-lignin polymer composite material.

[0111] 2. Preparation of lignin-based adhesives:

[0112] 1) Add gallic acid to glycine cholate, with a mass ratio of gallic acid to glycine cholate of 1:6, and stir to dissolve to obtain a polyphenol-ionic liquid;

[0113] 2) Add lignin to polyphenol-ionic liquid, with a mass ratio of gallic acid to alkali lignin of 1:3.5, and sonicate at 55℃ for 20 min to dissolve it, obtaining a mixed solution.

[0114] 3) Continue heating until the temperature of the mixed solution reaches 90℃, then add polyvinyl alcohol and succinic anhydride. The mass ratio of polyvinyl alcohol, succinic anhydride and lignin is 7:5:12. Stir and react for 7 hours to obtain lignin-based adhesive.

[0115] 3. Mix the raw materials of the adhesive layer evenly according to the weight proportions, heat to 90℃, and maintain for 20 minutes to obtain the adhesive layer.

[0116] Comparative Example 1

[0117] Without adding lignin-based adhesives, the rest is the same as in Example 5.

[0118] Comparative Example 2

[0119] In the preparation method of lignin-based adhesive, polyphenols are not added, i.e., step 1) is removed by adding lignin to the direct ionic liquid, and the rest is the same as in Example 5.

[0120] Comparative Example 3

[0121] In the preparation method of lignin-based adhesive, succinic anhydride in step 3) is removed, and the rest is the same as in Example 5.

[0122] Comparative Example 4

[0123] The graphene-lignin polymer composite material was not added; otherwise, it was the same as in Example 5.

[0124] Comparative Example 5

[0125] In the preparation method of graphene-lignin polymer composite material, step S1, i.e., graphene oxide, is removed without pretreatment, and the rest is the same as in Example 5.

[0126] Comparative Example 6

[0127] In the preparation method of graphene-lignin polymer composite material, step S2 is removed, which is the removal of lignin / silver nanoparticles, and the rest is the same as in Example 5.

[0128] The tapes obtained in Examples 1-5 and Comparative Examples 1-6 (all using carbon fiber substrate) were subjected to performance tests, and the results are listed in Table 1.

[0129] Tensile strength test: The test was conducted in accordance with GB / T 30776-2014 "Test methods for tensile strength and elongation at break of adhesive tape".

[0130] Peel strength test: The test was conducted in accordance with GB / T 2792-2014 "Test method for 180° peel strength of pressure sensitive adhesive tape".

[0131] Resistance test: The test shall be conducted in accordance with GB / T 42909-2023 "Conductive adhesive tape for wireless terminal equipment".

[0132] Table 1

[0133] Tensile strength (MPa) Peel strength (gf / inch) Vertical resistance (Ω) Horizontal resistance (Ω) Example 1 14.65 1523 3.3 4.4 Example 2 14.50 1561 2.8 4.1 Example 3 15.05 1602 3.2 4.3 Example 4 14.86 1625 3.1 3.9 Example 5 15.32 1650 2.6 3.8 Comparative Example 1 9.22 1225 3.9 5.0 Comparative Example 2 10.75 1348 3.7 4.8 Comparative Example 3 10.30 1372 3.7 4.7 Comparative Example 4 11.03 1305 5.4 6.7 Comparative Example 5 13.55 1491 4.0 5.6 Comparative Example 6 13.86 1380 4.8 6.1

[0134] As shown in Table 1, comparing Example 5 with Comparative Examples 1-6, it was found that: lignin-based adhesives, polyphenols and succinic anhydride in lignin-based adhesives, graphene-lignin polymer composites, and lignin / silver nanoparticles in graphene-lignin polymer composites have a significant impact on peel strength (adhesion); lignin-based adhesives, polyphenols and succinic anhydride in lignin-based adhesives, and graphene-lignin polymer composites have a significant impact on tensile strength (mechanical properties); graphene-lignin polymer composites, lignin / silver nanoparticles in graphene-lignin polymer composites, and graphene oxide pretreatment have a significant impact on resistivity. The tape provided by this invention has the advantages of low resistance, high adhesion, and high mechanical strength, meeting the performance requirements of precision connections inside electronic products.

[0135] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength, low-resistance adhesive tape for precision internal connections in electronic products, characterized in that, The material comprises a substrate layer and an adhesive layer disposed on the surface of the substrate layer, wherein the adhesive layer comprises the following raw materials in parts by weight: 40-70 parts of acrylic adhesive, 30-60 parts of lignin-based adhesive, 15-30 parts of graphene-lignin polymer composite material, 5-15 parts of maleic anhydride, 2-10 parts of conductive particles, 5-15 parts of crosslinking agent, and 2-10 parts of initiator; The lignin-based adhesive is obtained by reacting lignin with polyvinyl alcohol; The preparation method of the graphene-lignin polymer composite material includes the following steps: S1. Graphene oxide is dispersed in water, a surfactant is added, and the mixture is ultrasonically treated for a period of time. The graphene oxide is then separated by filtration. The treated graphene oxide is dispersed in a eutectic solvent, stirred for a period of time, washed with ethanol, and separated by filtration to obtain pretreated graphene. S2. Lignin is dissolved in NaOH solution to obtain a lignin solution. Ammonia water is added to silver nitrate aqueous solution to obtain [Ag(NH3)2]. + Complex solution; lignin solution is added dropwise to [Ag(NH3)2] + The complex solution was stirred and reacted in the dark for a period of time, then dialyzed and freeze-dried to obtain lignin / silver nanoparticles; S3. Disperse phosphorus-containing polymer, pretreated graphene, and lignin / silver nanoparticles in a solution of conductive monomers, add an initiator, and carry out in-situ polymerization at room temperature to obtain graphene-lignin polymer composite material.

2. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 1, characterized in that, The preparation method of the lignin-based adhesive includes the following steps: 1) Add polyphenols to an ionic liquid and stir to dissolve them, thus obtaining a polyphenol-ionic liquid; 2) Add lignin to the polyphenol-ionic liquid and sonicate it at 40-70℃ to dissolve it, thus obtaining a mixed solution; 3) Continue heating the mixture to 80-100℃, add polyvinyl alcohol and succinic anhydride, stir and react for a period of time to obtain lignin-based adhesive.

3. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 2, characterized in that, In step 1): Polyphenols include at least one of quercetin, tannic acid, dopamine, catechol, gallic acid, and epigallocatechin gallate. Ionic liquids include at least one of 1-ethyl-3-methylimidazolium acetate, alanine cholate, glycine cholate, lysine cholate, and threonine cholate. The mass ratio of polyphenols to ionic liquids is 1:(1-10).

4. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 2, characterized in that, In step 2): Lignin includes at least one of sulfonated lignin, hydroxylated lignin, carboxylated lignin, and alkali lignin; The mass ratio of polyphenols to lignin is 1:(2-5); The ultrasound frequency is 20–30 kHz, and the duration is 10–30 min.

5. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 2, characterized in that, In step 3): The mass ratio of polyvinyl alcohol, succinic anhydride and lignin is (1-5):(1-5):(2-10); The stirring reaction time is 5 to 10 hours.

6. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 1, characterized in that, In step S1: Surfactants include at least one of polyvinyl alcohol, polyethylene glycol, sodium lignosulfonate, polyvinylpyrrolidone (PVP), or sodium dodecylbenzenesulfonate; The amount of surfactant used is 2 to 10 wt% of the mass of graphene oxide; Eutectic solvents include one of the following: choline chloride-urea eutectic solvents and choline chloride-lactic acid eutectic solvents; The amount of eutectic solvent used is 1 to 10 times the mass of graphene oxide. The frequency of ultrasonic treatment is 20–30 kHz, and the duration is 10–30 min; The stirring temperature is 20–30℃, and the processing time is 8–10 hours.

7. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 1, characterized in that, In step S2: Lignin includes at least one of sulfonated lignin, hydroxylated lignin, carboxylated lignin, and alkali lignin; Lignin solution and [Ag(NH3)2] + In the complex solution, lignin reacts with [Ag(NH3)2]. + The mass ratio of the complex is (1-3):1; The temperature of the stirring reaction is 20–40℃, and the time is 12–24 h.

8. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 1, characterized in that, In step S3: The mass ratio of phosphorus-containing polymer, pretreated graphene, lignin / silver nanoparticles and conductive monomer is (1-2):(2-5):(5-10):(1-3); Conductive monomers include at least one of styrene and pyrrole; Initiators include at least one of ammonium persulfate, potassium persulfate, and sodium persulfate; The amount of initiator used is 1 to 10 wt% of the mass of the conductive monomer.

9. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 1, characterized in that, The raw materials of the adhesive layer include: The conductive particles include at least one of carbon nanotubes, graphene, zinc oxide, aluminum powder, magnesium powder, tin powder, and copper powder. The crosslinking agent includes at least one of benzamide peroxide, dicumyl peroxide, di-tert-butyl peroxide, and dicumyl peroxide. The initiator includes at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

10. The high-strength, low-resistance tape for precision internal connections in electronic products according to claim 1, characterized in that, The method for preparing the adhesive layer includes: mixing the raw materials of the adhesive layer evenly, heating to 80-100℃, and maintaining for 10-30 minutes.