Preparation method of touch-to-connect conductive adhesive

Abstract

The invention discloses a method for preparing a light-touch conductive adhesive. The invention prepares epoxy-modified acrylic resin by synthesis, uses acrylic soft monomers in combination with epoxy groups, and adds chain branches to the linear structure to increase the cohesion system and flexibility of the glue system while having ultra-high initial adhesion. Branched nickel powder is used as a conductive filler, which can be matched with glue having a linear chain and a linear branched chain structure, and the filler ratio will not be reduced while the cohesion of the glue system is increased. The invention also prepares a branched polyether with an epoxy end group, enhances the dispersibility of the branched nickel powder in the pressure-sensitive adhesive, and introduces an ether group to increase the impact resistance of the pressure-sensitive adhesive. The light-touch conductive adhesive prepared by the invention has ultra-high conductivity, does not reduce cohesion, has good initial adhesion and processing performance, and can be applied to the needs of small-area lamination of copper foil, conductive cloth, conductive non-woven fabric or substrate-free.

Description

Technical Field

[0001] The present invention relates to the technical field of acrylic adhesives, in particular to a method for preparing a touch-and-go conductive adhesive. Background Art

[0002] Consumer electronics are increasingly used in our daily lives. With the expansion of 5G technology, these products are becoming increasingly intelligent and lightweight, placing increasing demands on the components within them. On the one hand, the intelligent nature of consumer electronics requires electronic components to operate under higher-frequency electromagnetic waves, which severely interfere with these components, placing higher demands on the shielding effectiveness of shielding materials. On the other hand, the lightweight nature of consumer electronics requires smaller electronic components, leaving less space for shielding materials to be bonded. This increasingly smaller bonding area places even higher demands on the adhesion and shielding effectiveness of electromagnetic shielding. This is especially true in the context of high-speed mechanized production, where lower bonding pressure and shorter bonding times pose significant challenges to the initial adhesion of pressure-sensitive adhesives and the conductivity of conductive adhesives after bonding over small areas.

[0003] Among existing adhesive systems, pressure-sensitive adhesives made with acrylic resins have excellent flexibility and initial adhesion, making them widely used. However, due to the inherently low hardness of acrylics, pressurized lamination can lead to the risk of adhesive overflow around the die-cut parts or in the center of the ring. This is particularly prone to adhesive overflow during high-temperature processes, resulting in poor module performance. Adhesives made with two-component epoxy resins, while containing epoxy groups, offer excellent weather resistance and high hardness. However, they are brittle, have poor impact resistance, and exhibit low initial adhesion, making them prone to chip dropout during rapid lamination.

[0004] Whether using acrylic or epoxy systems, achieving touch-and-go superconductivity requires ensuring that every point of the conductive adhesive is conductive after contact with the substrate. This requires specially treated or morphologically specific conductive fillers in the adhesive system, as well as a high dosage. The addition of conductive powders can disrupt the adhesive system, prompting the development of specialized pressure-sensitive adhesives with high initial tack and cohesion.

[0005] Reference document CN 112195005 A describes a self-synthesized epoxy-modified acrylic resin, synthesized from polyethylene glycol diglycidyl ether epoxy resin and acrylamide. After synthesis, the epoxy groups dominate, resulting in a high cohesive adhesive system. Furthermore, conventional spherical and quasi-spherical conductive powders used to prepare single-sided adhesive for standard conductive fabrics exhibit excellent anti-seepage properties. However, because the epoxy groups dominate the adhesive system, its high cohesion lacks the characteristic of high initial adhesion. Furthermore, this high cohesiveness prevents the adhesive system from encapsulating large amounts of conductive fillers, making it unsuitable for small-area bonding applications, limiting its scope of application.

[0006] Existing technologies cannot meet the needs of small-area bonding applications, prompting us to develop a conductive pressure-sensitive adhesive that can be bonded quickly and turned on with a light touch. Summary of the Invention

[0007] The object of the present invention is to provide a method for preparing a touch-through conductive adhesive to solve the problems raised in the above background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a touch-through conductive adhesive having the following characteristics: the touch-through conductive adhesive comprises the following components, calculated by weight: 95-100 parts of modified epoxy resin glue, 0.8-1.2 parts of curing agent, and 20-50 parts of conductive filler;

[0009] The modified epoxy resin glue comprises the following components: 45-60 parts of modified epoxy resin, 15-22.5 parts of acrylate soft monomer, 0.1-2.5 parts of acrylic functional monomer, 30-37.5 parts of solvent, and 0.1-0.5 parts of initiator.

[0010] Furthermore, the touch-and-go conductive adhesive further comprises the following components, calculated by weight: 5-10 parts of tackifying resin and 0-12 parts of branched polyether.

[0011] Furthermore, the conductive filler is a branched chain nickel powder, which is composed of single particles with a diameter of 1-2 μm linked to each other, and D50=17-23 μm.

[0012] Furthermore, the acrylic acid ester soft monomer is one or more of isooctyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl methacrylate, and lauryl (meth)acrylate;

[0013] The acrylate functional monomer is one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, glycidyl methacrylate, and hydroxybutyl (meth)acrylate.

[0014] Furthermore, the solvent is any one or more of ethyl acetate, n-butyl acetate, and butanone;

[0015] The initiator is at least one of azobisisoheptanenitrile, benzoyl peroxide, lauroyl peroxide, and tert-butyl perbenzoate.

[0016] Furthermore, the tackifying resin is at least one of a rosin resin or a terpene resin having a softening point between 70-110°C;

[0017] The curing agent is an isocyanate curing agent.

[0018] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0019] S1. Dissolve polybis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin in an organic solvent, mix well, heat to 90-100°C, under nitrogen atmosphere, add 4-methyl-2-pentenamide in ethyl acetate dropwise for 2-3 hours, continue reflux reaction for 1-2 hours after addition, and rotary evaporate the reaction product to obtain a modified epoxy resin;

[0020] S2. The modified epoxy resin prepared in step S1 is mixed with an organic solvent, heated to 85-95 ° C, and a mixture of an acrylate soft monomer, an acrylic functional monomer and 70-80% of an initiator is added dropwise. After the reaction for 1-2h, the remaining initiator is added dropwise, and the reaction is continued for 1-2h to obtain a modified epoxy resin glue;

[0021] S3. The modified epoxy resin glue prepared in step S2 is mixed with the conductive filler, protected by a nitrogen atmosphere, stirred and mixed for 1-1.5 hours, and then a tackifying resin and a curing agent are added and mixed evenly to obtain the touch-through conductive adhesive.

[0022] Furthermore, in step S2, the epoxy content of the polybis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin is 0.25-0.40 mol / 100 g in terms of molar fractions;

[0023] Furthermore, the molar ratio of epoxy group to 4-methyl-2-pentenamide in the polybis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin is (1.8-2):1.

[0024] Furthermore, in step S3, when the modified epoxy resin glue is mixed with the conductive filler, a branched polyether is also added;

[0025] The preparation method of the branched polyether comprises the following steps:

[0026] a1. Dihydroxybenzoic acid and butyl glycidyl ether were mixed and dissolved in N,N-dimethylformamide, tetrabutylammonium bromide was added dropwise, nitrogen atmosphere was protected, the temperature was raised to 90-100 ° C in a water bath, and the reaction was refluxed for 8-12h. The reaction product was rotary evaporated to remove excess solvent and washed several times with deionized water, and then dried in vacuo to obtain a polyether prepolymer;

[0027] a2. Dissolve the polyether prepolymer in N,N-dimethylformamide, add boron trifluoride etherate, stir evenly, purge with nitrogen for 0.5-1 hour, slowly add epichlorohydrin dropwise, raise the temperature to 60-70°C, keep the reaction warm for 4-8 hours, rotary evaporate the reaction product to remove excess solvent, cool to room temperature, add sodium hydroxide solution dropwise, raise the temperature to 70-80°C in a water bath, react for 1-1.5 hours, rotary evaporate to remove water, filter to remove the precipitate, and collect the viscous oily liquid to obtain the branched polyether.

[0028] Furthermore, in step a1, the molar ratio of dihydroxybenzoic acid, butyl glycidyl ether, and tetrabutylammonium bromide is (0.8-1.2): (1-1.5): (0.01-0.03) by mole.

[0029] Furthermore, in step a2, the molar ratio of the polyether prepolymer, boron trifluoride ethyl ether, epichlorohydrin, and sodium hydroxide is (0.8-1.2):(0.05-0.1):(32-72):(24-48).

[0030] In order to improve the performance of a pressure-sensitive adhesive, the present invention first synthesizes a modified epoxy resin. During the resin synthesis process, epoxy, hydroxyl, and carboxyl groups are introduced. In addition, linear olefinamide is used to introduce linear branches into the linear epoxy structure. This reduces the brittleness of the system caused by the introduction of the branched chains, increases the flexibility of the cured colloid, and avoids the hard and brittle disadvantages of conventional epoxy systems after curing.

[0031] Since the conductive filler used in the present invention is a branched nickel powder, its surface shape is more easily entangled than that of conventional nickel powder, resulting in difficulty in dispersion of the nickel powders, and thus difficulty in dispersion of the branched nickel powder in the pressure-sensitive adhesive. Therefore, the present invention additionally prepares a branched polyether, and utilizes its unique branched structure to enhance the dispersibility of the branched nickel powder in the pressure-sensitive adhesive system. At the same time, the end group of the branched polyether prepared in the present invention is an epoxy group, which reacts with the acrylic monomer under the action of an initiator, introducing an epoxy group into the pressure-sensitive adhesive system, thereby enhancing the aging resistance of the pressure-sensitive adhesive system. The ether group contained therein has high flexibility, which can effectively improve the impact resistance of the pressure-sensitive adhesive.

[0032] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention prepares epoxy-modified acrylic resin through synthesis, uses acrylic soft monomers with epoxy groups, and adds chain branches to the linear structure to increase the cohesion system and flexibility of the glue system, while having ultra-high initial adhesion, and uses branched nickel powder as a conductive filler, which can be matched with glues with linear and linear branched structures, increasing the filler ratio without reducing the cohesion of the glue system, and the present invention also prepares branched polyethers with terminal epoxy groups, enhances the dispersibility of branched nickel powder in pressure-sensitive adhesives, and introduces ether groups to increase the impact resistance of pressure-sensitive adhesives; the touch-and-go conductive adhesive prepared by the present invention has ultra-high conductivity, does not reduce cohesion, has good initial adhesion and processing performance, and can be applied to copper foil, conductive cloth, conductive non-woven fabrics or small-area lamination needs without substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0034] Figure 1 This is the morphology of the conductive filler used in the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] The bis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin used in this embodiment is a commercially available bis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin with the model number UVR-6128, which has a molecular weight of 366.45 and an epoxy equivalent weight of 190-210 g / mol;

[0037] The conductive filler used in this application is nickel powder with model number DCX-10 sold by North Star High-tech Materials Technology Co., Ltd.

[0038] Example 1.

[0039] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0040] S2. By weight, 45 parts of the modified epoxy resin prepared in step S2 were stirred and mixed with 30 parts of butanone, heated to 85 ° C, and a mixture of 15 parts of 2-ethylhexyl acrylate, 0.1 parts of 2-hydroxypropyl acrylate and 0.07 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.03 parts of BPO initiator was added dropwise, and the reaction was continued for 1 hour to obtain a modified epoxy resin glue;

[0041] S3. By weight, 100 parts of the epoxy resin glue prepared in step S2 were mixed with 20 parts of conductive filler under nitrogen atmosphere, stirred for 1 hour, and then 5 parts of terpene resin were added and mixed. Then, the conductive filler was added and stirred for 30 minutes, and then 0.8 parts of isocyanate curing agent was added and mixed evenly to obtain the touch-through conductive adhesive.

[0042] Example 2.

[0043] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0044] S2. By weight, 45 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 30 parts of butanone, heated to 85 ° C, and a mixture of 15 parts of 2-ethylhexyl acrylate, 0.1 parts of 2-hydroxypropyl acrylate and 0.07 parts of BPO initiator was added dropwise. After reacting for 1 hour, 0.03 parts of BPO initiator was added dropwise, and the reaction was continued for 1 hour to obtain a modified epoxy resin glue;

[0045] S3. By weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 20 parts of conductive filler, protected by a nitrogen atmosphere, and stirred for 1 hour. Then, 5 parts of terpene resin and 0.8 parts of isocyanate curing agent were added and mixed evenly to obtain the touch-through conductive adhesive.

[0046] Example 3.

[0047] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0048] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0049] S2. By weight, 50 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 30 parts of butanone, heated to 85 ° C, and a mixture of 15 parts of 2-ethylhexyl acrylate, 0.5 parts of 2-hydroxypropyl acrylate and 0.05 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.04 parts of BPO initiator was added dropwise, and the reaction was continued for 2 hours to obtain a modified epoxy resin glue;

[0050] S3. In parts by weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 20 parts of a conductive filler and 4 parts of a branched polyether prepared in step S1, and the mixture was stirred under a nitrogen atmosphere for 1 hour. Then, 5 parts of a terpene resin and 0.8 parts of an isocyanate curing agent were added and mixed to obtain the touch-through conductive adhesive.

[0051] The preparation of the branched polyether comprises the following steps:

[0052] a1. In molar parts, 0.8 parts of dihydroxybenzoic acid and 1 part of butyl glycidyl ether were mixed and dissolved in 10 parts of N, N-dimethylformamide, 0.01 parts of tetrabutylammonium bromide were added dropwise, nitrogen atmosphere was protected, the water bath was heated to 90 ° C, refluxed for 8h, the reaction product was rotary evaporated to remove excess solvent, and washed 8 times with deionized water, and dried in vacuo at 60 ° C for 8h to obtain a polyether prepolymer;

[0053] a2. According to the molar ratio, 0.8 parts of the polyether prepolymer was dissolved in 10 parts of N,N-dimethylformamide, 0.05 parts of boron trifluoride ether were added, and the mixture was stirred evenly. After nitrogen was purged for 0.5h, the temperature was raised to 60°C, and 32 parts of epichlorohydrin were slowly added dropwise for 4h. After that, the reaction was continued at this temperature for 4h. The reaction product was rotary evaporated to remove excess solvent. After cooling to room temperature, a sodium hydroxide solution containing 24 parts of sodium hydroxide was added dropwise. The temperature was raised to 70°C in a water bath. After the reaction was allowed to react for 1h, the water was rotary evaporated to remove the water, and the precipitate was removed by filtration. The viscous oily liquid was collected to obtain a branched polyether.

[0054] Example 4.

[0055] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0056] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0057] S2. By weight, 50 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 37.5 parts of butanone, heated to 90 ° C, and a mixture of 22.5 parts of 2-ethylhexyl acrylate, 2.5 parts of 2-hydroxypropyl acrylate and 0.4 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.1 parts of BPO initiator was added dropwise, and the reaction was continued for 2 hours to obtain a modified epoxy resin glue;

[0058] S3. In parts by weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 20 parts of a conductive filler and 4 parts of a branched polyether prepared in step S1, and stirred under a nitrogen atmosphere for 1 hour. Then, 10 parts of a terpene resin and 1.2 parts of an isocyanate curing agent were added and mixed to obtain the touch-through conductive adhesive.

[0059] The preparation of the branched polyether comprises the following steps:

[0060] a1. In molar parts, 0.8 parts of dihydroxybenzoic acid and 1 part of butyl glycidyl ether were mixed and dissolved in 10 parts of N, N-dimethylformamide, 0.01 parts of tetrabutylammonium bromide were added dropwise, nitrogen atmosphere was protected, the water bath was heated to 90 ° C, refluxed for 8h, the reaction product was rotary evaporated to remove excess solvent, and washed 8 times with deionized water, and dried in vacuo at 60 ° C for 8h to obtain a polyether prepolymer;

[0061] a2. According to the molar ratio, 0.8 parts of the polyether prepolymer was dissolved in 10 parts of N,N-dimethylformamide, 0.05 parts of boron trifluoride ether were added, and the mixture was stirred evenly. After nitrogen was purged for 0.5h, the temperature was raised to 60°C, and 32 parts of epichlorohydrin were slowly added dropwise for 4h. After that, the reaction was continued at this temperature for 4h. The reaction product was rotary evaporated to remove excess solvent. After cooling to room temperature, a sodium hydroxide solution containing 24 parts of sodium hydroxide was added dropwise. The temperature was raised to 70°C in a water bath. After the reaction was allowed to react for 1h, the water was rotary evaporated to remove the water, and the precipitate was removed by filtration. The viscous oily liquid was collected to obtain a branched polyether.

[0062] Example 5.

[0063] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0064] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0065] S2. By weight, 50 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 30 parts of butanone, heated to 85 ° C, and a mixture of 15 parts of 2-ethylhexyl acrylate, 2.5 parts of 2-hydroxypropyl acrylate and 0.4 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.1 parts of BPO initiator was added dropwise, and the reaction was continued for 2 hours to obtain a modified epoxy resin glue;

[0066] S3. In parts by weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 50 parts of a conductive filler and 4 parts of a branched polyether prepared in step S1, and stirred under a nitrogen atmosphere for 1 hour. After that, 5 parts of a terpene resin and 0.8 parts of an isocyanate curing agent were added and mixed to obtain the touch-through conductive adhesive.

[0067] The preparation of the branched polyether comprises the following steps:

[0068] a1. In molar parts, 0.8 parts of dihydroxybenzoic acid and 1 part of butyl glycidyl ether were mixed and dissolved in 10 parts of N, N-dimethylformamide, 0.01 parts of tetrabutylammonium bromide were added dropwise, nitrogen atmosphere was protected, the water bath was heated to 90 ° C, refluxed for 8h, the reaction product was rotary evaporated to remove excess solvent, and washed 8 times with deionized water, and dried in vacuo at 60 ° C for 8h to obtain a polyether prepolymer;

[0069] a2. In molar parts, 0.8 parts of a polyether prepolymer was dissolved in 10 parts of N, N- dimethylformamide, 0.05 parts of boron trifluoride ether were added, stirred, and purged with nitrogen for 0.5h, the temperature was raised to 60 ° C, 32 parts of epichlorohydrin were slowly added dropwise, the addition time was 4h, and then the reaction was continued for 4h, the reaction product was rotary evaporated to remove excess solvent, and after cooling to room temperature, a sodium hydroxide solution containing 24 parts of sodium hydroxide was added dropwise, and the water bath was heated to 70 ° C. After the reaction for 1h, the water was rotary evaporated to remove the water, and after filtering to remove the precipitate, the viscous oily liquid was collected to obtain a branched polyether;

[0070] Example 6.

[0071] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0072] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 100°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 3 hours. After the addition is completed, reflux reaction is continued for 2 hours, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0073] S2. In parts by weight, 60 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 37.5 parts of ethyl acetate, heated to 95 ° C, and a mixture of 22.5 parts of acrylate soft monomer, 2.5 parts of acrylic functional monomer and 0.4 parts of azobisisoheptanenitrile initiator was added dropwise. After the reaction for 2 hours, 0.1 parts of azobisisoheptanenitrile initiator was added dropwise, and the reaction was continued for 2 hours to obtain a modified epoxy resin glue;

[0074] S3. In parts by weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 50 parts of the conductive filler and 12 parts of the branched polyether prepared in step S1, and the mixture was stirred under a nitrogen atmosphere for 1h. Then, 10 parts of a terpene resin and 1.2 acid ester curing agent were added and mixed to obtain the touch-through conductive adhesive.

[0075] The preparation of the branched polyether comprises the following steps:

[0076] a1. In molar parts, 1.2 parts of dihydroxybenzoic acid and 1.5 parts of butyl glycidyl ether were mixed and dissolved in 10 parts of N, N- dimethylformamide, 0.03 parts of tetrabutylammonium bromide was added dropwise, nitrogen atmosphere was protected, the water bath was heated to 100 ° C, refluxed for 12h, the reaction product was rotary evaporated to remove excess solvent, and washed 8 times with deionized water, and dried in vacuo at 60 ° C for 8h to obtain a polyether prepolymer;

[0077] a2. According to the molar ratio, 1.2 parts of the polyether prepolymer were dissolved in 10 parts of N,N-dimethylformamide, 0.1 parts of boron trifluoride ether were added, and the mixture was stirred evenly. After nitrogen purge for 1 hour, the temperature was raised to 70 ° C, and 72 parts of epichlorohydrin were slowly added dropwise for 4 hours. After that, the reaction was continued at this temperature for 8 hours. The reaction product was rotary evaporated to remove excess solvent. After cooling to room temperature, a sodium hydroxide solution containing 48 parts of sodium hydroxide was added dropwise. The temperature was raised to 80 ° C in a water bath. After the reaction was allowed to react for 1.5 hours, the water was rotary evaporated to remove water, and the precipitate was removed by filtration. The viscous oily liquid was collected to obtain a branched polyether.

[0078] Comparative Example 1.

[0079] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 57.13 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.66. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0080] S2. By weight, 50 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 30 parts of butanone, heated to 90 ° C, and a mixture of 15 parts of 2-ethylhexyl acrylate, 0.5 parts of 2-hydroxypropyl acrylate and 0.05 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.04 parts of BPO initiator was added dropwise, and the reaction was continued for 2 hours to obtain an epoxy resin glue;

[0081] S3. By weight, 100 parts of the epoxy resin glue prepared in step S2 were mixed with 20 parts of conductive filler and 12 parts of the branched polyether prepared in step S1, protected by a nitrogen atmosphere, stirred and mixed for 1 hour, and then 5 parts of terpene resin were added and mixed. The conductive filler was added and stirred for 30 minutes, and then 0.8 parts of isocyanate curing agent was added and mixed. After mixing evenly, the touch-through conductive adhesive was obtained.

[0082] Comparative Example 2.

[0083] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0084] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0085] S2. By weight, 50 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 37.5 parts of butanone, heated to 85 ° C, and a mixture of 25 parts of 2-ethylhexyl acrylate, 2.5 parts of 2-hydroxypropyl acrylate and 0.4 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.2 parts of BPO initiator was added dropwise, and the reaction was continued for 2 hours to obtain a modified epoxy resin glue;

[0086] S3. In parts by weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 50 parts of a conductive filler and 4 parts of a branched polyether prepared in step S1, and stirred under a nitrogen atmosphere for 1 hour. Then, 10 parts of a terpene resin and 1.2 parts of an isocyanate curing agent were added and mixed to obtain the touch-through conductive adhesive.

[0087] The preparation of the branched polyether comprises the following steps:

[0088] a1. In molar parts, 0.8 parts of dihydroxybenzoic acid and 1 part of butyl glycidyl ether were mixed and dissolved in 10 parts of N, N-dimethylformamide, 0.01 parts of tetrabutylammonium bromide were added dropwise, nitrogen atmosphere was protected, the water bath was heated to 90 ° C, refluxed for 8h, the reaction product was rotary evaporated to remove excess solvent, and washed 8 times with deionized water, and dried in vacuo at 60 ° C for 8h to obtain a polyether prepolymer;

[0089] a2. According to the molar ratio, 0.8 parts of the polyether prepolymer was dissolved in 10 parts of N,N-dimethylformamide, 0.05 parts of boron trifluoride ether were added, and the mixture was stirred evenly. After nitrogen was purged for 0.5h, the temperature was raised to 60°C, and 32 parts of epichlorohydrin were slowly added dropwise for 4h. After that, the reaction was continued at this temperature for 4h. The reaction product was rotary evaporated to remove excess solvent. After cooling to room temperature, a sodium hydroxide solution containing 24 parts of sodium hydroxide was added dropwise. The temperature was raised to 70°C in a water bath. After the reaction was allowed to react for 1h, the water was rotary evaporated to remove the water, and the precipitate was removed by filtration. The viscous oily liquid was collected to obtain a branched polyether.

[0090] Comparative Example 3.

[0091] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0092] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0093] S2. By weight, 50 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 37.5 parts of butanone, heated to 85 ° C, and a mixture of 25 parts of 2-ethylhexyl acrylate, 2.5 parts of 2-hydroxypropyl acrylate and 0.4 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.1 parts of BPO initiator was added dropwise, and the reaction was continued for 2 hours to obtain a modified epoxy resin glue;

[0094] S3. In parts by weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 20 parts of a conductive filler and 8 parts of a branched polyether prepared in step S1, and stirred under a nitrogen atmosphere for 1 hour. Then, 10 parts of a terpene resin and 1.2 parts of an isocyanate curing agent were added and mixed to obtain the touch-through conductive adhesive.

[0095] The preparation of the branched polyether comprises the following steps:

[0096] a1. In molar parts, 0.8 parts of dihydroxybenzoic acid and 1 part of butyl glycidyl ether were mixed and dissolved in 10 parts of N, N-dimethylformamide, 0.01 parts of tetrabutylammonium bromide were added dropwise, nitrogen atmosphere was protected, the water bath was heated to 90 ° C, refluxed for 8h, the reaction product was rotary evaporated to remove excess solvent, and washed 8 times with deionized water, and dried in vacuo at 60 ° C for 8h to obtain a polyether prepolymer;

[0097] a2. According to the molar ratio, 0.8 parts of the polyether prepolymer was dissolved in 10 parts of N,N-dimethylformamide, 0.05 parts of boron trifluoride ether were added, and the mixture was stirred evenly. After nitrogen was purged for 0.5h, the temperature was raised to 60°C, and 32 parts of epichlorohydrin were slowly added dropwise for 4h. After that, the reaction was continued at this temperature for 4h. The reaction product was rotary evaporated to remove excess solvent. After cooling to room temperature, a sodium hydroxide solution containing 24 parts of sodium hydroxide was added dropwise. The temperature was raised to 70°C in a water bath. After the reaction was allowed to react for 1h, the water was rotary evaporated to remove the water, and the precipitate was removed by filtration. The viscous oily liquid was collected to obtain a branched polyether.

[0098] Comparative Example 4.

[0099] A method for preparing a touch-through conductive adhesive comprises the following steps:

[0100] S1. Dissolve 70 parts of polybis((3,4-epoxycyclohexyl)methyl) adipate epoxy resin in a mixed solvent of 65 parts of ethyl acetate and 40 parts of butanone, mix well, heat to 90°C, protect under nitrogen atmosphere, and dropwise add 43.1 parts of 4-methyl-2-pentenamide in ethyl acetate, wherein the molar ratio of epoxy group content to alkenylamide group content in the epoxy resin is 1:0.5. The addition time is 2 hours. After the addition is completed, reflux reaction is continued for 1 hour, and the reaction product is rotary evaporated to obtain a modified epoxy resin;

[0101] S2. By weight, 50 parts of the modified epoxy resin prepared in step S1 were stirred and mixed with 30 parts of butanone, heated to 85 ° C, and a mixture of 15 parts of 2-ethylhexyl acrylate, 0.5 parts of 2-hydroxypropyl acrylate and 0.05 parts of BPO initiator was added dropwise. After reacting for 2 hours, 0.04 parts of BPO initiator was added dropwise, and the reaction was continued for 2 hours to obtain a modified epoxy resin glue;

[0102] S3. In parts by weight, 100 parts of the modified epoxy resin glue prepared in step S2 were mixed with 20 parts of nickel powder sold by Qinghe County Benyu Metal Materials Co., Ltd. model BY-NI and 8 parts of the branched polyether prepared in step S1, protected by a nitrogen atmosphere, stirred and mixed for 1h, and then 5 parts of terpene resin and 0.8 parts of isocyanate curing agent were added and mixed to obtain the touch-through conductive adhesive;

[0103] The preparation of the branched polyether comprises the following steps:

[0104] a1. In molar parts, 0.8 parts of dihydroxybenzoic acid and 1 part of butyl glycidyl ether were mixed and dissolved in 10 parts of N, N-dimethylformamide, 0.01 parts of tetrabutylammonium bromide were added dropwise, nitrogen atmosphere was protected, the water bath was heated to 90 ° C, refluxed for 8h, the reaction product was rotary evaporated to remove excess solvent, and washed 8 times with deionized water, and dried in vacuo at 60 ° C for 8h to obtain a polyether prepolymer;

[0105] a2. According to the molar ratio, 0.8 parts of the polyether prepolymer was dissolved in 10 parts of N,N-dimethylformamide, 0.05 parts of boron trifluoride ether were added, and the mixture was stirred evenly. After nitrogen was purged for 0.5h, the temperature was raised to 60°C, and 32 parts of epichlorohydrin were slowly added dropwise for 4h. After that, the reaction was continued at this temperature for 4h. The reaction product was rotary evaporated to remove excess solvent. After cooling to room temperature, a sodium hydroxide solution containing 24 parts of sodium hydroxide was added dropwise. The temperature was raised to 70°C in a water bath. After the reaction was allowed to react for 1h, the water was rotary evaporated to remove the water, and the precipitate was removed by filtration. The viscous oily liquid was collected to obtain a branched polyether.

[0106] Testing: The conductive adhesives prepared in Examples 1-5 and Comparative Examples 1-5 were coated on 25 μm PET to form a 5 μm dry adhesive. After aging at 48°C for 24 hours, the basic properties were tested. The peel strength test was conducted in accordance with the standard "Test Method for Peel Strength of Adhesive Tapes" (GB / T2792-2014); the holding force test was conducted in accordance with the "Test Method for Adhesive Tape Holding Properties" (GB / T 4851-2014); the impact resistance test was conducted in accordance with (GB / T 3808-2018). The sample structure was 25 μm conductive adhesive + 25 μm PET + 25 μm conductive adhesive, with a total thickness of 75 μm.

[0107]

[0108]

[0109] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0110] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A touch-on conductive adhesive, characterized by: The touch-on conductive adhesive comprises the following components, in parts by weight: 95-100 parts of modified epoxy resin adhesive, 0.8-1.2 parts of curing agent, and 20-50 parts of conductive filler; wherein the modified epoxy resin adhesive comprises the following components: 45-60 parts of modified epoxy resin, 15-22.5 parts of acrylate soft monomer, 0.1-2.5 parts of acrylic functional monomer, 30-37.5 parts of solvent, and 0.1-0.5 parts of initiator; the conductive filler is branched nickel powder; The touch-and-go conductive adhesive also includes the following components: 5-10 parts of a tackifying resin and 0-12 parts of a branched polyether; the tackifying resin is at least one of a rosin resin or a terpene resin; the curing agent is an isocyanate curing agent; the modified epoxy resin is synthesized from polybis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin and 4-methyl-2-pentenamide, wherein the molar content ratio of the epoxy group to the molar content of the alkenylamide group in the epoxy resin is 1:0.5; the branched polyether is produced by grafting dihydroxybenzoic acid with butyl glycidyl ether and then reacting with epichlorohydrin.

2. The touch-and-go conductive adhesive according to claim 1, characterized in that: The acrylic acid ester soft monomer is one or more of isooctyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, n-decyl methacrylate, and lauryl (meth)acrylate; The acrylic functional monomer is one or more of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, glycidyl methacrylate, and hydroxybutyl (meth)acrylate.

3. The touch-and-go conductive adhesive according to claim 1, characterized in that: The solvent is any one or more of ethyl acetate, n-butyl acetate, and butanone; The initiator is at least one of azobisisoheptanenitrile, benzoyl peroxide, lauroyl peroxide, and tert-butyl perbenzoate.

4. The method for preparing a touch-on conductive adhesive according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Dissolve polybis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin in an organic solvent, mix well, heat to 90-100°C, under nitrogen atmosphere, add 4-methyl-2-pentenamide in ethyl acetate dropwise for 2-3 hours, continue reflux reaction for 1-2 hours after addition, and rotary evaporate the reaction product to obtain a modified epoxy resin; S2. The modified epoxy resin prepared in step S1 is mixed with an organic solvent, heated to 85-95 ° C, and a mixture of an acrylate soft monomer, an acrylic functional monomer and 70-80% of an initiator is added dropwise. After the reaction for 1-2h, the remaining initiator is added dropwise, and the reaction is continued for 1-2h to obtain a modified epoxy resin glue; S3. The modified epoxy resin glue prepared in step S2 is mixed with the conductive filler, protected by a nitrogen atmosphere, stirred and mixed for 1-1.5 hours, and then a tackifying resin and a curing agent are added and mixed evenly to obtain the touch-through conductive adhesive.

5. The method for preparing a touch-on conductive adhesive according to claim 4, characterized in that: In step S2, the epoxy content of the polybis((3,4-epoxycyclohexyl)methyl)adipate epoxy resin is 0.25-0.40 mol / 100 g in terms of molar fraction.

6. The method for preparing a touch-on conductive adhesive according to claim 4, wherein: In step S3, when the modified epoxy resin glue is mixed with the conductive filler, a branched polyether is also added; wherein the preparation method of the branched polyether comprises the following steps: a1. Dihydroxybenzoic acid and butyl glycidyl ether were mixed and dissolved in N,N-dimethylformamide, tetrabutylammonium bromide was added dropwise, nitrogen atmosphere was protected, the temperature was raised to 90-100 ° C in a water bath, and the reaction was refluxed for 8-12h. The reaction product was rotary evaporated to remove excess solvent and washed several times with deionized water, and then dried in vacuo to obtain a polyether prepolymer; a2. Dissolve the polyether prepolymer in N,N-dimethylformamide, add boron trifluoride etherate, stir evenly, purge with nitrogen for 0.5-1 hour, slowly add epichlorohydrin dropwise, raise the temperature to 60-70°C, keep the reaction warm for 4-8 hours, rotary evaporate the reaction product to remove excess solvent, cool to room temperature, add sodium hydroxide solution dropwise, raise the temperature to 70-80°C in a water bath, react for 1-1.5 hours, rotary evaporate to remove water, filter to remove the precipitate, and collect the viscous oily liquid to obtain the branched polyether.

7. The method for preparing a touch-on conductive adhesive according to claim 6, wherein: In step a1, the molar ratio of dihydroxybenzoic acid, butyl glycidyl ether, and tetrabutylammonium bromide is (0.8-1.2): (1-1.5): (0.01-0.03) by mole.

8. The method for preparing a touch-on conductive adhesive according to claim 6, wherein: In step a2, the molar ratio of the polyether prepolymer, boron trifluoride ethyl ether, epichlorohydrin, and sodium hydroxide is (0.8-1.2):(0.05-0.1):(32-72):(24-48).

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