Conductive ink suitable for double light calendered copper foil and preparation method and application thereof

Abstract

The application discloses a conductive ink suitable for double light calendered copper foil and a preparation method and application thereof. The conductive ink comprises the following components: a connecting material, conductive particles, a functional mixed solvent and an additive, wherein the functional mixed solvent contains strong organic acid. The conductive ink suitable for double light calendered copper foil provided by the application can corrode the passivation layer on the surface of the double light calendered copper foil by adding strong organic acid, increase the roughness of the copper foil and improve the adhesion of the conductive ink on the surface of the copper foil. The conductive ink can be directly applied on the surface of the double light calendered copper foil and has good adhesion and conductivity.

Description

Technical Field

[0001] This invention relates to a conductive ink, specifically a conductive ink suitable for double-light rolled copper foil, its preparation method and application, belonging to the field of conductive ink preparation technology. Background Technology

[0002] Copper foil is an important chemical raw material, a primary component in the production of printed circuit boards, copper-clad laminates, lithium batteries, and other electronic components. Based on manufacturing processes, it can be divided into electrolytic copper foil and rolled copper foil. Electrolytic copper foil is currently the mainstream material in the market due to its low cost and ease of production. However, in applications requiring high performance in bending, flexibility, and tear resistance, such as flexible copper-clad laminates, rolled copper foil still holds irreplaceable advantages.

[0003] Due to its unique manufacturing process, rolled copper foil has an extremely low surface roughness, typically less than 1μm. Combined with a passivation layer, this makes it very difficult for ordinary ink coatings to adhere to the surface of double-coated rolled copper foil.

[0004] Currently, there are three main surface treatment methods for rolled copper foil on the market: blackening treatment (copper-cobalt-nickel or copper-nickel plating), redening treatment (pure copper plating), and zinc-nickel plating. The main process flow is: chemical degreasing - water washing - pickling - water washing - roughening treatment - water washing - pickling - zinc alloy or zinc-nickel alloy plating - water washing - passivation - water washing - coating with silane coupling agent - drying. After surface treatment, the roughness of the rolled copper foil is increased, which significantly improves the adhesion of ink to its surface. However, at the same time, the plating also increases the hardness of the copper foil, weakening the most significant advantage of the rolled copper foil—flexibility—making it unsuitable for specific applications such as electromagnetic shielding in display modules. Moreover, surface treatment also significantly increases the cost of copper foil. Therefore, it is necessary to develop a conductive ink that can be directly applied to the surface of untreated double-sided rolled copper foil.

[0005] Conductive inks are mainly composed of binders, conductive particles, solvents, and additives. Conductive particles are the key to the conductivity of the ink. Common conductive particles are mainly divided into two categories: metallic (gold, silver, copper, nickel, silver-coated copper, nickel-coated copper, etc.) and carbon-based (conductive carbon black, graphite, carbon nanotubes, graphene, etc.). Generally, metallic conductive particles have stronger conductivity than carbon-based conductive particles. Therefore, in fields where high conductivity is required, metallic conductive particles are mainly added.

[0006] The binder is generally a polymer resin, which forms the main body of conductive ink and determines its properties such as adhesion, hardness, and curing conditions. Commonly used resin systems on the market include polyurethane, polyester, acrylic, and epoxy. However, for untreated double-coated copper foil, conductive inks made from these resin systems cannot achieve ideal adhesion when applied directly.

[0007] Currently, existing technologies for improving the adhesion of conductive inks to the surface of double-coated copper foil include:

[0008] (1) Roughening the surface of double-light rolled copper foil, but this weakens the flexibility advantage of rolled copper foil and increases costs significantly, resulting in poor economic benefits.

[0009] (2) Before coating with conductive ink, the double-coated copper foil is pickled and washed with water to remove the surface passivation layer, improve roughness, and enhance the adhesion of the ink to its surface. However, most coating plants only have coating machines and lack the equipment for front-end pickling and washing, and adding such equipment would require a large capital investment. Alternatively, the copper foil manufacturer could be asked to remove the passivation layer, but the copper foil would undergo oxidation and corrosion during transportation or storage, making large-scale production impossible.

[0010] In conclusion, there is currently no effective method on the market to directly apply conventional conductive inks to double-coated copper foil. It is necessary to upgrade the conductive ink formulation to improve its adhesion to the surface of double-coated copper foil. Summary of the Invention

[0011] The main objective of this invention is to provide a conductive ink suitable for double-light rolled copper foil and its preparation method, so as to overcome the shortcomings of the prior art.

[0012] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0013] This invention provides a conductive ink suitable for double-coated copper foil, comprising the following components: binder, conductive particles, functional mixed solvent and additives, wherein the functional mixed solvent contains a strong organic acid.

[0014] In some embodiments, the strong organic acid may be at least one of trifluoromethanesulfonic acid, trinitrobenzenesulfonic acid, benzohexacarboxylic acid, etc.

[0015] In some embodiments, the conductive ink comprises the following components by mass fraction: 12-20 wt% binder, 40-60 wt% conductive particles, 20-40 wt% functional mixed solvent, and 1-5 wt% additives.

[0016] In some embodiments, the functional mixed solvent includes at least one of ester organic solvents, ketone organic solvents, and also includes strong organic acids.

[0017] The present invention also provides a method for preparing the aforementioned conductive ink suitable for double-glazed rolled copper foil, comprising: mixing the binder, conductive particles, functional mixed solvent and additives uniformly to obtain the conductive ink suitable for double-glazed rolled copper foil.

[0018] In some embodiments, the preparation method includes:

[0019] At least one of the ester organic solvents and ketone organic solvents in the functional mixed solvent and the additives are stirred and mixed evenly at a first speed. Then, conductive particles are added and stirred and mixed evenly at a second speed. Then, binder is added and dispersed evenly at a third speed. Finally, the obtained mixture is ground to obtain a conductive slurry.

[0020] The remaining functional mixed solvent is mixed with the conductive paste and stirred at a fourth rotation speed until homogeneous. After filtration, the viscosity and solid content are adjusted with at least one of ester organic solvents and ketone organic solvents to obtain the conductive ink suitable for double-light calendered copper foil.

[0021] This invention also provides a method for coating conductive ink suitable for double-glazed rolled copper foil, comprising: coating the conductive ink suitable for double-glazed rolled copper foil onto the surface of the double-glazed rolled copper foil at least twice.

[0022] Accordingly, embodiments of the present invention also provide a conductive ink coating, which is formed by coating the surface of the double-light-calendered copper foil with the aforementioned conductive ink suitable for double-light-calendered copper foil.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The conductive ink for double-glazed rolled copper foil provided by this invention adds a strong organic acid to corrode the passivation layer on the surface of the double-glazed rolled copper foil, thereby increasing the roughness of the copper foil and improving the adhesion of the conductive ink to the copper foil surface. This conductive ink can be directly applied to the surface of double-glazed rolled copper foil and has good adhesion and conductivity. Detailed Implementation

[0025] To overcome the shortcomings of the existing technology, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The main feature is the development of a conductive ink that can be directly applied to the surface of double-coated copper foil, exhibiting excellent adhesion and conductivity. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0026] One aspect of the present invention provides a conductive ink suitable for double-coated copper foil, comprising the following components: binder, conductive particles, functional mixed solvent and additives, wherein the functional mixed solvent contains a strong organic acid.

[0027] In some embodiments, the conductive ink has a viscosity of 1000-5000 cps and a solid content of 35-60%.

[0028] In some embodiments, the strong organic acid may be at least one of trifluoromethanesulfonic acid, trinitrobenzenesulfonic acid, and benzenehexacarboxylic acid, but is not limited thereto. This invention adds a strong organic acid, preferably trifluoromethanesulfonic acid, to the conductive ink. The strong acidity and corrosiveness of trifluoromethanesulfonic acid to metal surfaces disrupt the passivation layer on the surface of the double-coated copper foil, while simultaneously increasing the roughness of the copper foil, thereby improving the adhesion and abrasion resistance of the conductive ink on the copper foil surface.

[0029] In some embodiments, the conductive ink suitable for double-sided calendered copper foil comprises, by mass fraction, the following components: 12-20 wt% binder, 40-60 wt% conductive particles, 20-40 wt% functional mixed solvent and 1-5 wt% additives.

[0030] In some embodiments, the binder may include any one or a combination of two or more of polyester, polyurethane, polyester polyol, epoxy resin, etc., but is not limited thereto.

[0031] Furthermore, the epoxy resin may be any one or a combination of two or more of the following: ES-510 from SK Corporation of Korea, VYLON240 from Toyobo, AL-540C from Arakawa Chemical, 5778P from Lubrizol, 7287 from Shanghai Xiaoyan Technology, 1256 epoxy resin from Mitsubishi, NPEL128 epoxy resin from Nanya, etc., but is not limited to these.

[0032] In some embodiments, the conductive particles may include any one or a combination of two or more of conductive nickel powder, conductive silver powder, silver-coated copper powder, graphene, etc., but are not limited thereto.

[0033] Furthermore, the median particle size (D50) of the conductive particles is 2–5 μm.

[0034] Furthermore, the shape of the conductive particles includes any one or a combination of two or more of the following structures: sheet-like, spherical, and dendritic, but is not limited thereto. This invention, by using a combination of metal conductive particles of different sizes and structures (sheet-like, spherical, and dendritic) to bridge each other, greatly reduces the surface resistance of the ink.

[0035] In some embodiments, the functional mixed solvent includes a strong organic acid, and at least one of ester organic solvents, ketone organic solvents, etc. The ester organic solvent may include, but is not limited to, any one or a combination of two or more of mixed acid dimethyl ester, propylene glycol methyl ether acetate, butyl acetate, ethyl acetate, etc. Further, the ketone organic solvent may include, but is not limited to, any one or a combination of two of butanone, cyclohexanone, etc.

[0036] Furthermore, the functional mixed solvent contains trifluoromethanesulfonic acid, and also includes any one or a combination of two of dimethyl sulfoxide (DMSO) and dimethylformamide (DMF). The strong organic acid in this invention is added after being mixed with a specific organic solvent (i.e., the aforementioned dimethyl sulfoxide, dimethylformamide, etc.) to avoid incompatibility with the system and resulting in undesirable phenomena such as layering and precipitation. That is, based on the good compatibility of trifluoromethanesulfonic acid with strongly polar organic solvents, adding trifluoromethanesulfonic acid to the conductive ink system using DMSO and DMF will not result in layering or precipitation.

[0037] In some embodiments, the additives include any one or a combination of two or more of the following additives: dispersants, coupling agents, adhesion promoters, defoamers, and curing agents, but are not limited thereto.

[0038] Specifically, the additives may be any one or a combination of two or more of the following: BYK-111, Evka 4010, Lubrizol 20000, KH550, KH560, Changxing 4901-B-72, Digo SF-200, Huaxia HX-2080, Gifu XE-14, BYK-410, Wanhua HT-100, Bayer 3390, amino curing agents, etc., but are not limited thereto.

[0039] Another aspect of the present invention provides a method for preparing a conductive ink suitable for double-glazed rolled copper foil, comprising: mixing the aforementioned binder, conductive particles, functional mixed solvent and additives uniformly according to mass fractions to obtain the conductive ink suitable for double-glazed rolled copper foil.

[0040] In some embodiments, the preparation method may specifically include:

[0041] At least one of the ester organic solvents and ketone organic solvents in the functional mixed solvent and the additives are stirred and mixed evenly at a first speed. Then, conductive particles are added and stirred and mixed evenly at a second speed. Then, binder is added and dispersed evenly at a third speed. Finally, the obtained mixture is ground to obtain a conductive slurry.

[0042] The remaining functional mixed solvent is mixed with the conductive paste and stirred at a fourth rotation speed until homogeneous. After filtration, the viscosity and solid content are adjusted with at least one of ester organic solvents and ketone organic solvents to obtain the conductive ink suitable for double-light calendered copper foil.

[0043] Furthermore, the first rotational speed is 400–600 r / min.

[0044] Furthermore, the second rotational speed is 600–800 r / min.

[0045] Furthermore, the third rotational speed is 400–600 r / min.

[0046] Furthermore, the process parameters used in the grinding include: the particle size of the grinding media is 0.6 to 1.5 mm, the rotation speed of the sand mill is 1000 to 2000 r / min, the air pressure for the first grinding pass is 0.2 to 0.4 MPa, the air pressure for the second and subsequent passes is 0.1 to 0.3 MPa, the number of grinding passes is 4 to 5, until the fineness is <5 μm.

[0047] Furthermore, the fourth rotational speed is 600–800 r / min.

[0048] Furthermore, the filter cloth used for filtration is 150-300 mesh.

[0049] In some more specific embodiments, the method for preparing the conductive ink suitable for double-light rolled copper foil may specifically include the following steps:

[0050] (1) Add the mixed organic solvent (ester organic solvent, ketone organic solvent, etc.) and additives to the preparation tank in proportion. Disperse the mixture at a speed of 400-600 r / min. While dispersing, add conductive particle powder. Increase the speed to 600-800 r / min and disperse for about 10 min. Then add the binder (i.e., resin) and adjust the speed to 400-600 r / min. Disperse for 30 min. Then transfer the mixture to a sand mill for grinding. The zirconium bead particle size in the sand mill is 0.8 mm. Set the sand mill speed to 1500 r / min. The air pressure for the first grinding is 0.3 MPa. After the second grinding, adjust the air pressure to 0.2 MPa. Grind 4-5 times until the fineness is <5 μm to obtain the conductive slurry semi-finished product.

[0051] (2) Add the remaining mixed solvent (trifluoromethanesulfonic acid, dimethyl sulfoxide, dimethylformamide, etc.) to the conductive slurry semi-finished product, disperse it in a disperser at 600-800 r / min for 20 min, filter it with a 200 mesh filter cloth at the outlet, and then adjust the viscosity and solid content with organic solvent to obtain a conductive ink suitable for the surface of double-light rolled copper foil.

[0052] Another aspect of the present invention provides a conductive ink suitable for the surface of double-light rolled copper foil, prepared by any of the foregoing preparation methods.

[0053] Another aspect of the present invention provides a method for coating conductive ink, comprising: coating the conductive ink suitable for double-glazed calendered copper foil onto the surface of the double-glazed calendered copper foil at least twice.

[0054] The conductive ink coating method of this invention involves applying two layers of ink to the copper foil surface, resulting in better performance than a single coating. This is because the first coating layer corrodes and breaks down the passivation layer, increasing surface roughness and allowing the conductive ink to initially bond with the copper foil. During the second coating, the first ink layer serves as a primer, resulting in a tighter bond between the conductive ink and the first ink layer. Simultaneously, this improves both the appearance and overall performance of the coating. In other words, the first ink layer acts as a base, enhancing the adhesion and abrasion resistance of the entire conductive ink layer.

[0055] Among them, the product performance is optimal when the thickness of each coating layer is 2μm.

[0056] Furthermore, another aspect of the present invention provides a conductive ink coating, which is formed by coating the surface of the double-brushed copper foil with the aforementioned conductive ink suitable for double-brushed copper foil.

[0057] When the thickness of the conductive ink coating is 4μm, its surface resistance can reach below 50mΩ.

[0058] Furthermore, the adhesion of the conductive ink coating is 5B.

[0059] Furthermore, the conductive ink coating has a rubber rubbing resistance (500gf load) of >200 times and an alcohol rubbing resistance (500gf load) of >100 times.

[0060] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, and do not constitute any limitation thereof. 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. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the manufacturer.

[0061] In this invention's embodiments, all solid resins must first be dissolved into a resin liquid before being formulated into conductive ink. The specific dissolution method is as follows: Propylene glycol methyl ether acetate (PMA), cyclohexanone, and butanone are mixed in a 3:2:1 ratio. Solid resin is added while dispersing in a disperser. The container is sealed, and the rotation speed is increased to 2000-3000 r / min for high-speed dispersion for 2-4 hours until all resins are completely dissolved. After adding the total weight, the mixture is allowed to stand and cool for later use. Subsequent additions of solid resin will all be in the form of a resin liquid.

[0062] Example 1

[0063] (1) Mix 500g methyl ethyl ketone, 500g ethyl acetate, 100g BYK-111, 100g adhesion promoter Changxing 4901-B-72, and 20g defoamer SF-200 at a speed of 600r / min until uniform. Add 1200g dendritic nickel powder with D50 of 3μm, 400g flake nickel powder, and 50g graphene. Disperse at a speed of 600r / min for 30min. Add 1500g polyester resin liquid ES-510 and continue dispersing at a speed of 600r / min. Transfer to a sand mill and sand mill four times. The fineness is tested by a scraper fineness meter and the fineness is <3μm to obtain a conductive paste semi-finished product.

[0064] (2) After mixing 150g of trifluoromethanesulfonic acid and 300g of dimethyl sulfoxide evenly, add it to the conductive paste semi-finished product, then add 150g of HT-100, disperse at a speed of 600r / min for 20min, add a mixed solvent of butanone and ethyl acetate to adjust the solid content and viscosity, filter with a 200-mesh filter cloth, and obtain a conductive ink finished product suitable for the surface of double-light rolled copper foil.

[0065] (3) The ink was coated onto the surface of the rolled copper foil in two stages by micro-gravure coating. After baking at 120℃ for 3 min, the foil was rolled up and then cured at 50℃ for 72 hours. The performance was then tested and the results are shown in Table 1.

[0066] Example 2

[0067] (1) Mix 500g methyl ethyl ketone, 500g ethyl acetate, 100g BYK-111, 100g adhesion promoter Changxing 4901-B-72, and 20g defoamer SF-200 at a speed of 600r / min until uniform. Add 1200g dendritic nickel powder with D50 of 3μm, 400g flake nickel powder, and 50g graphene. Disperse at a speed of 600r / min for 30min. Add 2500g polyester resin liquid ES-510 and continue to disperse at a speed of 600r / min. Transfer to a sand mill and sand mill four times. The fineness is tested by a scraper fineness meter and the fineness is <3μm to obtain a conductive paste semi-finished product.

[0068] (2) After mixing 150g of trifluoromethanesulfonic acid and 300g of dimethyl sulfoxide evenly, add it to the conductive paste semi-finished product, then add 150g of HT-100, disperse at a speed of 600r / min for 20min, add a mixed solvent of butanone and ethyl acetate to adjust the solid content and viscosity, filter with a 200-mesh filter cloth, and obtain a conductive ink finished product suitable for the surface of double-light rolled copper foil.

[0069] (4) The ink was coated onto the surface of the rolled copper foil in two stages by micro-gravure coating. After baking at 120℃ for 3 min, the foil was rolled up and then cured at 50℃ for 72 hours. The performance was then tested, and the results are shown in Table 1.

[0070] Example 3

[0071] (1) Mix 500g methyl ethyl ketone, 500g ethyl acetate, 100g BYK-111, 100g adhesion promoter Changxing 4901-B-72, and 20g defoamer SF-200 at a speed of 600r / min until uniform. Add 2000g dendritic nickel powder with D50 of 3μm, 1000g flake nickel powder, and 50g graphene. Disperse at a speed of 600r / min for 30min. Add 1500g polyester resin liquid ES-510 and continue dispersing at a speed of 600r / min. Transfer to a sand mill and sand mill four times. The fineness is tested by a scraper fineness meter and the fineness is <3μm to obtain a conductive paste semi-finished product.

[0072] (2) After mixing 150g of trifluoromethanesulfonic acid and 300g of dimethyl sulfoxide evenly, add it to the conductive paste semi-finished product, then add 150g of HT-100, disperse at a speed of 600r / min for 20min, add a mixed solvent of butanone and ethyl acetate to adjust the solid content and viscosity, filter with a 200-mesh filter cloth, and obtain a conductive ink finished product suitable for the surface of double-light rolled copper foil.

[0073] (3) The ink was coated onto the surface of the rolled copper foil in two stages by micro-gravure coating. After baking at 120℃ for 3 min, the foil was rolled up and then cured at 50℃ for 72 hours. The performance was then tested and the results are shown in Table 1.

[0074] Example 4

[0075] (1) 500g of butanone, 500g of propylene glycol methyl ether acetate (PMA), 100g of Efka 4010, 100g of silane coupling agent KH550, and 20g of defoamer HX2080 were mixed evenly at a speed of 500r / min. 1200g of dendritic nickel powder with a D50 of 3μm and 400g of flake silver powder were added and dispersed at a speed of 600r / min for 30min. 1500g of polyester resin liquid Toyobo VYLON240 was added and dispersed at a speed of 500r / min. The mixture was then transferred to a sand mill and sand-milled four times. The fineness was tested by a scraper fineness meter and found to be <3μm, thus obtaining a conductive paste semi-finished product.

[0076] (2) After mixing 150g of trifluoromethanesulfonic acid and 300g of dimethylformamide (DMF) evenly, add it to the conductive paste semi-finished product, then add 150g of HT-100, disperse at a speed of 600r / min for 20min, add a mixed solvent of butanone and ethyl acetate to adjust the solid content and viscosity, filter with a 200-mesh filter cloth, and obtain a conductive ink finished product suitable for the surface of double-light rolled copper foil.

[0077] (3) The ink was coated onto the surface of the rolled copper foil in two stages by micro-gravure coating. After baking at 120℃ for 3 min, the foil was rolled up and then cured at 50℃ for 72 hours. The performance was then tested and the results are shown in Table 1.

[0078] Example 5

[0079] (1) Mix 500g methyl ethyl ketone, 500g mixed acid dimethyl ester, 100g Lubrizol 2000, 100g silane coupling agent KH560 and 20g BYK410 at a speed of 400r / min until uniform. Add 1500g resin liquid Lubrizol 5778P and continue to disperse at a speed of 800r / min. Add 1200g dendritic nickel powder with D50 of 3μm, 400g flake nickel powder and 50g graphene. Disperse at a speed of 500r / min for 30min. Transfer to a sand mill and sand mill four times. The fineness is tested by a scraper fineness meter and the fineness is <3μm to obtain a conductive paste semi-finished product.

[0080] (2) After mixing 150g trifluoromethanesulfonic acid, 150g dimethyl sulfoxide (DMSO) and 150g dimethylformamide (DMF) evenly, add them to the conductive paste semi-finished product, then add 150g HT-100, disperse at 800r / min for 20min, add methyl ethyl ketone and ethyl acetate mixed solvent to adjust the solid content and viscosity, filter with 200 mesh filter cloth, and obtain a conductive ink finished product suitable for the surface of double-light rolled copper foil.

[0081] (3) The ink was coated onto the surface of the rolled copper foil in two stages by micro-gravure coating. After baking at 120℃ for 3 min, the foil was rolled up and then cured at 50℃ for 72 hours. The performance was then tested and the results are shown in Table 1.

[0082] Example 6

[0083] (1) Mix 500g methyl ethyl ketone, 500g mixed acid dimethyl ester, 100g Lubrizol 2000, 100g silane coupling agent KH560 and 20g BYK410 at a speed of 400r / min until uniform. Add 1500g resin liquid Lubrizol 5778P and continue to disperse at a speed of 800r / min. Add 1200g dendritic nickel powder with D50 of 3μm, 400g flake nickel powder and 50g graphene. Disperse at a speed of 500r / min for 30min. Transfer to a sand mill and sand mill four times. The fineness is tested by a scraper fineness meter and the fineness is <3μm to obtain a conductive paste semi-finished product.

[0084] (2) After mixing 150g of trinitrobenzenesulfonic acid, 150g of dimethyl sulfoxide (DMSO) and 150g of dimethylformamide (DMF) evenly, add them to the conductive paste semi-finished product, then add 150g of HT-100, disperse at 800r / min for 20min, add methyl ethyl ketone and ethyl acetate mixed solvent to adjust the solid content and viscosity, filter with 200 mesh filter cloth, and obtain a conductive ink finished product suitable for the surface of double-light rolled copper foil.

[0085] (4) The ink was coated onto the surface of the rolled copper foil in two stages by micro-gravure coating. After baking at 120℃ for 3 min, the foil was rolled up and then cured at 50℃ for 72 hours. The performance was then tested, and the results are shown in Table 1.

[0086] Example 7

[0087] (1) 500g butyl acetate, 500g cyclohexanone, 100g BYK-111, 100g adhesion promoter Changxing 4901-B-72, and 20g defoamer SF-200 were mixed evenly at a speed of 400r / min. 1200g of dendritic nickel powder with D50 of 3μm, 400g of flake nickel powder, and 50g of graphene were added and dispersed at a speed of 600r / min for 30min. 1500g of resin liquid Nanya NPEL128 was added and dispersed at a speed of 400r / min. The mixture was then transferred to a sand mill and sand-milled four times. The fineness was tested by a scraper fineness meter and found to be <3μm, thus obtaining a conductive paste semi-finished product.

[0088] (2) After mixing 150g of trifluoromethanesulfonic acid and 300g of dimethyl sulfoxide evenly, add them to the conductive paste semi-finished product and disperse at a speed of 400r / min for 20min. Add a mixture of butanone and ethyl acetate to adjust the solid content and viscosity. After filtering with a 200-mesh filter cloth, a conductive ink suitable for the surface of double-light rolled copper foil is obtained.

[0089] (3) Add 10-15% of the finished ink to an amino curing agent. Apply the ink to the surface of the rolled copper foil in two coats by micro-gravure coating. Bake at 130℃ for 3 min and then roll up. After curing at 50℃ for 72 hours, test the performance. The results are shown in Table 2.

[0090] Example 8

[0091] (1) 500g butyl acetate, 500g cyclohexanone, 100g BYK-111, 100g adhesion promoter Changxing 4901-B-72, and 20g defoamer SF-200 were mixed evenly at a speed of 400r / min. 1200g of dendritic nickel powder with D50 of 3μm, 400g of flake nickel powder, and 50g of graphene were added and dispersed at a speed of 600r / min for 30min. 1500g of resin liquid Nanya NPEL128 was added and dispersed at a speed of 400r / min. The mixture was then transferred to a sand mill and sand-milled four times. The fineness was tested by a scraper fineness meter and found to be <3μm, thus obtaining a conductive paste semi-finished product.

[0092] (2) After mixing 150g of benzene hexacarboxylic acid and 300g of dimethyl sulfoxide evenly, add it to the conductive paste semi-finished product and disperse it at a speed of 400r / min for 20min. Add a mixture of butanone and ethyl acetate to adjust the solid content and viscosity. After filtering with a 200-mesh filter cloth, a conductive ink suitable for the surface of double-light rolled copper foil is obtained.

[0093] (3) Add 10-15% of the finished ink to an amino curing agent. Apply the ink to the surface of the rolled copper foil in two coats by micro-gravure coating. Bake at 130℃ for 3 min and then roll up. After curing at 50℃ for 72 hours, test the performance. The results are shown in Table 2.

[0094] Comparative Example 1

[0095] (1) Mix 500g methyl ethyl ketone, 500g ethyl acetate, 100g BYK-111, 100g adhesion promoter Changxing 4901-B-72, and 20g defoamer SF-200 evenly. Add 1500g polyester resin liquid ES-510 and continue to disperse. Add 1200g dendritic nickel powder with D50 of 3μm, 400g flake nickel powder, and 50g graphene. Disperse at 600r / min for 30min. Transfer to a sand mill and sand mill four times. The fineness is tested by a scraper fineness meter and the fineness is <3μm to obtain a conductive paste semi-finished product.

[0096] (2) After mixing 150g of trifluoromethanesulfonic acid and 300g of dimethyl sulfoxide evenly, add it to the conductive paste semi-finished product, then add 150g of HT-100, disperse at a speed of 600r / min for 20min, add a mixed solvent of butanone and ethyl acetate to adjust the solid content and viscosity, filter with a 200-mesh filter cloth, and obtain a conductive ink finished product suitable for the surface of double-light rolled copper foil.

[0097] (3) The ink was coated onto the surface of the rolled copper foil in one go by micro-gravure coating. After baking at 120℃ for 3 min, it was rolled up and then cured at 50℃ for 72 hours. The performance was then tested and the results are shown in Table 2.

[0098] Comparative Example 2

[0099] (1) Mix 500g methyl ethyl ketone, 500g ethyl acetate, 100g BYK-111, 100g adhesion promoter Changxing 4901-B-72, and 20g defoamer SF-200 evenly. Add 1500g polyester resin liquid ES-510 and continue to disperse. Add 1200g dendritic nickel powder with D50 of 3μm, 400g flake nickel powder, and 50g graphene. Disperse at 600r / min for 30min. Transfer to a sand mill and sand mill four times. The fineness is tested by a scraper fineness meter and the fineness is <3μm to obtain a conductive paste semi-finished product.

[0100] (2) Add 150g of HT-100 to the conductive paste semi-finished product, disperse at 600r / min for 20min, add a mixed solvent of butanone and ethyl acetate to adjust the solid content and viscosity, filter with 200 mesh filter cloth, and obtain a conductive ink product suitable for the surface of double-light rolled copper foil.

[0101] (3) The ink was coated onto the surface of the rolled copper foil in two stages by micro-gravure coating. After baking at 120℃ for 3 min, the foil was rolled up and then cured at 50℃ for 72 hours. The performance was then tested and the results are shown in Table 2.

[0102] Table 1. Test results of basic properties of the inks prepared in Examples 1-6 and basic properties of the printing layers.

[0103]

[0104]

[0105] Table 2. Test results of basic properties of the inks prepared in Examples 7-8 and Comparative Examples 1-2, and basic properties of the printed layers.

[0106]

[0107]

[0108] According to Table 1, we can conclude that:

[0109] (1) Comparing Example 1 and Comparative Example 1, it can be seen that the ink adhesion and abrasion resistance are worse when coated once to 4μm than when coated twice. The reason is that when coated once, the ink does not have enough corrosiveness to the passivation layer on the copper foil surface and the bonding force with the copper foil is not strong.

[0110] (2) Comparing Example 1 and Comparative Example 2, it can be seen that without the addition of trifluoromethanesulfonic acid, the conductive ink has very poor adhesion to double-coated copper foil and poor abrasion resistance, failing to meet application requirements. However, with the addition of trifluoromethanesulfonic acid, both adhesion and abrasion resistance are significantly improved.

[0111] (3) Comparing Example 5 and Example 6, it can be seen that trinitromethanesulfonic acid is slightly less effective than trifluoromethanesulfonic acid in improving the alcohol resistance of conductive ink.

[0112] (4) Comparing Example 7 and Example 8, it can be seen that benzohexacarboxylic acid is slightly less effective than trifluoromethanesulfonic acid in improving the alcohol resistance of conductive ink.

[0113] (5) Overall, compared with conventional conductive inks, the conductive ink formulated in this invention can be directly applied to the surface of double-light rolled copper foil, with strong adhesion and good abrasion resistance, which can save equipment costs and broaden the application field of rolled copper foil.

[0114] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0115] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing a conductive ink coating, characterized in that, Conductive ink is directly coated onto the surface of double-coated copper foil at least twice to form a conductive ink coating. The conductive ink comprises the following components by mass fraction: 12-20 wt% binder, 40-60 wt% conductive particles, 20-40 wt% functional mixed solvent, and 1-5 wt% additives. The binder comprises any one or a combination of two or more of polyester, polyurethane, polyester polyol, and epoxy resin. The conductive particles comprise any one or a combination of two or more of conductive nickel powder, conductive silver powder, silver-coated copper powder, and graphene. The median particle size of the conductive particles is 2-5 µm. The functional mixed solvent comprises trifluoromethanesulfonic acid and at least one of ester organic solvents or ketone organic solvents. The additives comprise any one or a combination of two or more of dispersants, coupling agents, adhesion promoters, defoamers, and curing agents. The functional mixed solvent also includes any one or a combination of two of dimethyl sulfoxide and dimethylformamide.

2. The method for preparing the conductive ink coating according to claim 1, characterized in that: The conductive ink has a viscosity of 1000~5000cps and a solid content of 35~60%.

3. The method for preparing the conductive ink coating according to claim 1, characterized in that: The ester organic solvents include any one or a combination of two or more of the following: dimethyl ester, propylene glycol methyl ether acetate, butyl acetate, and ethyl acetate.

4. The method for preparing the conductive ink coating according to claim 1, characterized in that: The ketone organic solvents include any one or a combination of two of butanone and cyclohexanone.

5. The method for preparing the conductive ink coating according to claim 1, characterized in that: The epoxy resin includes any one or a combination of two or more of the following: SK Corporation of Korea ES-510, Toyobo VYLON240, Arakawa Chemical AL-540C, Lubrizol 5778P, Shanghai Xiaoyan Technology 7287, Mitsubishi 1256 epoxy resin, and Nanya NPEL128 epoxy resin.

6. The method for preparing the conductive ink coating according to claim 1, characterized in that: The shape of the conductive particles includes any one or a combination of two or more of the following: sheet-like, spherical, and dendritic.

7. The method for preparing the conductive ink coating according to claim 1, characterized in that: The additives include any one or a combination of two or more of the following: BYK-111, Evka 4010, Lubrizol 20000, KH550, KH560, Changxing 4901-B-72, Digo SF-200, Huaxia HX-2080, Gifu XE-14, BYK-410, Wanhua HT-100, Bayer 3390, and amino curing agents.

8. The method for preparing the conductive ink coating according to claim 1, characterized in that, The method for preparing the conductive ink includes: mixing the binder, conductive particles, functional mixed solvent and additives evenly to obtain the conductive ink.

9. The method for preparing the conductive ink coating according to claim 8, characterized in that, include: At least one of the ester organic solvents and ketone organic solvents in the functional mixed solvent and the additives are stirred and mixed evenly at a first speed. Then, conductive particles are added and stirred and mixed evenly at a second speed. Then, binder is added and dispersed evenly at a third speed. Finally, the obtained mixture is ground to obtain a conductive slurry. The remaining functional mixed solvent is mixed with the conductive paste and stirred at a fourth rotation speed until homogeneous. The mixture is then filtered, and the viscosity and solid content are adjusted with at least one of ester organic solvents and ketone organic solvents to obtain the conductive ink.

10. The method for preparing the conductive ink coating according to claim 9, characterized in that: The first rotational speed is 400~600 r / min.

11. The method for preparing the conductive ink coating according to claim 9, characterized in that: The second rotational speed is 600~800 r / min.

12. The method for preparing the conductive ink coating according to claim 9, characterized in that: The third rotational speed is 400~600 r / min.

13. The method for preparing the conductive ink coating according to claim 9, characterized in that: The grinding process parameters include: the particle size of the grinding media is 0.6~1.5mm, the rotation speed of the sand mill is 1000~2000r / min, the air pressure for the first grinding pass is 0.2~0.4MPa, the air pressure for the second and subsequent passes is 0.1~0.3MPa, the number of grinding passes is 4~5, until the fineness is <5μm.

14. The method for preparing the conductive ink coating according to claim 9, characterized in that: The fourth rotational speed is 600~800 r / min.

15. The method for preparing the conductive ink coating according to claim 9, characterized in that: The filter cloth used for filtration is 150-300 mesh.

16. A conductive ink coating, characterized in that, It is prepared by the preparation method according to any one of claims 1-15.

17. The conductive ink coating according to claim 16, characterized in that: When the thickness of the conductive ink coating is 4 μm, its surface resistance is below 50 mΩ.

18. The conductive ink coating according to claim 16, characterized in that: The adhesion of the conductive ink coating is 5B.

19. The conductive ink coating according to claim 16, characterized in that: The conductive ink coating has a rubber rubbing resistance of more than 200 times and an alcohol rubbing resistance of more than 100 times.

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