Low-solid-content high-conductivity silver paste for wind power generation and preparation method of low-solid-content high-conductivity silver paste

Abstract

The invention relates to the technical field of high-conductivity silver paste, in particular to low-solid-content high-conductivity silver paste for wind power generation and a preparation method of the low-solid-content high-conductivity silver paste. The invention discloses low-solid-content high-conductivity silver paste for wind power generation. The low-solid-content high-conductivity silver paste comprises the following substances in parts by weight: 20-50 parts of a conductive material; 3-5 parts of a blocked isocyanate curing agent; 3 to 10 parts of polyurethane; 58-70 parts of a solvent; 1-5 parts of a functional additive; the conductive material comprises silver coated copper powder and flake silver powder. The low-solid-content design is adopted, the cost is remarkably reduced, meanwhile, a composite conductive system of the silver-coated copper powder and the flaky silver powder is introduced, the low cost of the silver-coated copper powder and the high conductivity of the flaky silver powder are utilized, and the conductive performance is maintained while the silver consumption is reduced. Meanwhile, a low-temperature curing system is formed by combining polyurethane resin and a blocked isocyanate curing agent, the problem that an epoxy base material is damaged by high-temperature sintering of traditional silver paste is solved through the flexibility of polyurethane and the low-temperature reaction activity of the curing agent, and the vibration fatigue resistance of the coating is improved.

Description

Technical Field

[0001] The present application relates to the technical field of highly conductive silver pastes, and in particular to a low-solid-content, highly conductive silver paste for wind power generation and a preparation method thereof. Background Art

[0002] Wind power generation equipment is long-term exposed to extreme environments such as low temperature, high humidity, and salt spray. The conductive coating of its core component, the wind turbine blade, needs to have high conductivity, weather resistance, and anti-mechanical vibration ability. Among traditional conductive materials, carbon paste composites are widely used due to their light weight and high strength, but their resistivity (about 10⁻² Ω·cm) is several orders of magnitude higher than that of metal conductors, resulting in frequent lightning protection failure cases, and insufficient conductivity is likely to cause current transmission loss, affecting power generation efficiency. Although pure silver paste has excellent conductivity (in the order of 10-6–10-5 Ω·cm), the high silver content (solid content often >50%) leads to a sharp increase in cost (8000–10000 yuan / kg), and high-temperature sintering (>200 °C) is required, which cannot be adapted to heat-sensitive substrates such as epoxy resins, severely restricting its application in large blade manufacturing.

[0003] To balance cost and performance, copper powder is regarded as a substitute material due to its low price and high conductivity, but its easy oxidation characteristic leads to a sharp drop in conductivity. The silver-coated copper powder technology shows potential in the field of electronic pastes by plating silver on the surface, which can take into account antioxidant properties and conductivity, but existing research mainly focuses on electromagnetic shielding or flexible circuits and has not been optimized for wind power generation scenarios. For example, traditional silver-coated copper pastes still rely on high-temperature curing processes and lack targeted designs for the interfacial bonding of blade substrates, resulting in insufficient adhesion and easy cracking of the coating. In addition, the compounding system of nano silver particles and micron silver-coated copper powder in the existing technology is not yet mature, and the contact resistance cannot be effectively reduced through particle size gradient filling, restricting the improvement of conductive performance at low solid content. Summary of the Invention

[0004] In order to improve the defect of poor conductivity of existing conductive materials for wind power generation, the present application provides a low-solid-content, highly conductive silver paste for wind power generation and a preparation method thereof.

[0005] In the first aspect, the present application provides a low-solid-content, highly conductive silver paste for wind power generation, adopting the following technical solutions: A low-solid-content, highly conductive silver paste for wind power generation, comprising: 20-50 parts of conductive material; 3-5 parts of blocked isocyanate curing agent; 3-10 parts of polyurethane; 58-70 parts of solvent; 1-5 parts of functional additive; The conductive material includes silver-coated copper powder and flaky silver powder.

[0006] Through the above technical solutions, the present application adopts a low solid content design to significantly reduce costs. At the same time, a composite conductive system of silver-coated copper powder and flaky silver powder is introduced. By taking advantage of the low cost of silver-coated copper powder and the high conductivity of flaky silver powder, the silver usage is reduced while maintaining the conductive performance.

[0007] On this basis, the present application selects a combination of polyurethane resin and blocked isocyanate curing agent to form a low-temperature curing system. Through the flexibility of polyurethane and the low-temperature reaction activity of the curing agent, the problem of damage to epoxy substrates caused by high-temperature sintering of traditional silver pastes is solved, and the vibration fatigue resistance of the coating is improved. The introduction of functional additives further optimizes the dispersibility, adhesion and weather resistance, and overall achieves a balance of low cost, high conductivity and extreme environment adaptability.

[0008] Further, the organic solvent includes a mixed solvent of dibasic acid ester and propylene glycol methyl ether acetate; the dibasic acid ester is composed of dimethyl succinate, dimethyl glutarate and dimethyl adipate mixed in a mass ratio of (5-6):(18-20):(1-2).

[0009] Through the above technical solutions, the present application defines the specific composition and ratio of the organic solvent. The mixed solvent of dibasic acid ester (dimethyl succinate / dimethyl glutarate / dimethyl adipate) and propylene glycol methyl ether acetate (PMA) (mass ratio 6-7:1) has a high boiling point (150-200 °C) and strong dissolving ability, which can ensure the full dissolution of polyurethane resin and excellent leveling property of the slurry. The specific ratio of dimethyl succinate (short chain) and dimethyl glutarate / dimethyl adipate (long chain) adjusts the solvent evaporation gradient, avoids pinhole defects caused by too fast solvent evaporation during the coating process, and ensures a dense and pore-free coating after drying. The polar property of propylene glycol methyl ether acetate enhances the compatibility between the solvent and the resin, and further improves the storage stability of the slurry.

[0010] Further, the conductive material further includes 2-5 parts by weight of nano silver particles.

[0011] Through the above technical solutions, the present application introduces nano silver particles into the conductive phase. By filling the gaps between micron-sized silver-coated copper powder and flaky silver powder with nano particles, a multi-scale conductive network is formed. The high specific surface area and surface activity of nano silver can reduce the contact resistance between micron-sized particles, and at the same time enhance the mechanical strength of the coating. In addition, the addition of nano silver reduces the risk of oxidation exposure of silver-coated copper powder, and improves the conductive stability through the "micro-nano" synergistic effect.

[0012] Further, the particle size of the silver-coated copper powder is 5-6 μm, the particle size of the flaky silver powder is 2.5-4.5 μm, and the particle size of the nano silver particles is 150-400 nm.

[0013] Through the above technical solutions, the present application further defines the particle size range of the conductive material: the particle size of the silver-coated copper powder is 5-6 μm to ensure a high packing density and reduce the coating porosity; the flaky silver powder is 2.5-4.5 μm to increase the conductive contact area through the flat structure and reduce the lateral resistance; the nano silver particles are 150-400 nm to fill the gaps between the micron-sized particles and form a three-dimensional conductive path. The three optimize the packing efficiency through a gradient particle size distribution (0.5-3 μm mixed particle size), avoid the problem of increased porosity caused by a single particle size, and at the same time improve the rheological properties of the slurry.

[0014] Further, the mixing ratio of the dibasic acid ester to propylene glycol methyl ether acetate is (6-7):1.

[0015] Further, the functional additive includes tetraethyl titanate and a phosphoric acid polyester dispersant mixed in a mass ratio of (1-2):(0.5-2.0).

[0016] Through the above technical solutions, the present application defines the functional additive as a synergistic combination of tetraethyl titanate and a phosphoric acid polyester dispersant. Tetraethyl titanate, as a coupling agent, forms a titanate layer on the surface of the silver powder through hydrolysis and condensation reactions, enhancing the interfacial bonding force between the inorganic particles and the polyurethane resin; the phosphoric acid polyester dispersant prevents the silver powder from agglomerating through electrostatic repulsion and steric hindrance effects. The two synergistically improve the dispersion uniformity, coating denseness and long-term stability of the slurry, and at the same time reduce the porosity of the cured coating, further improving the conductivity.

[0017] In a second aspect, the present application provides a method for preparing a low-solid-content and high-conductive silver paste for wind power generation, adopting the following technical solutions: A method for preparing a low-solid-content and high-conductive silver paste for wind power generation, comprising the following preparation steps: S1. Conductive phase pretreatment: Mix the silver-coated copper powder, flaky silver powder and nano silver particles through a ball milling process, control the particle size distribution of the mixed powder to be 0.5-3 μm, and collect the conductive phase; S2. Organic carrier synthesis: Dissolve the polyurethane resin in an organic solvent at 80-85 °C, stir until completely dissolved and then filter to collect the organic carrier; S3. Slurry preparation: Mix the conductive phase, tetraethyl titanate and the organic carrier, add the phosphoric acid polyester dispersant after high-speed dispersion, and grind to a fineness of ≤5 μm by series sand milling treatment; S4. Viscosity adjustment: Add a solvent to adjust the viscosity to 500-1000 cp, and prepare the low-solid-content and high-conductive silver paste for wind power generation through vacuum degassing.

[0018] Through the above technical solutions, in this application, the uniform mixing and particle size distribution control (0.5 - 3 μm) of micro / nano particles are first achieved through the ball milling process, breaking the soft agglomeration of silver-coated copper powder and avoiding the discontinuity of the conductive network after coating. At the same time, this application adopts the scheme of synthesizing low-temperature organic carriers to avoid the degradation of polyurethane resin caused by high temperature and maintain the integrity of the resin molecular chain, thereby ensuring the flexibility and adhesion of the coating. Finally, this application uses a series of sand mills to refine particles in stages and combines vacuum deaeration to eliminate micropores, ensuring high density and low resistivity of the slurry.

[0019] Further, the series sand grinding treatment described in step S3 includes the following steps: First, use zirconium beads with a diameter of 0.8 - 1.0 mm and grind at 2500 - 3000 r / min until the fineness is ≤ 6 μm; then use zirconium beads with a diameter of 0.2 - 0.5 mm and grind at 3000 - 3500 r / min until the fineness is ≤ 3 μm.

[0020] Through the above technical solutions, in this application, large particle agglomerates are first rapidly broken by the first-stage sand grinding, and the particle size is initially reduced to ≤ 6 μm, avoiding the low grinding efficiency caused by directly using small zirconium beads. Then, through the high-frequency collision of small and medium-sized zirconium beads in the second-stage sand grinding, the particles are further refined to ≤ 3 μm, ensuring the uniform dispersion of nano silver particles and filling the micron-level gaps. This staged grinding strategy takes into account both efficiency and precision, reduces particle breakage caused by over-grinding, and at the same time reduces energy consumption.

[0021] In summary, this application includes at least one of the following beneficial technical effects: 1. This application adopts a low solid content design to significantly reduce costs. At the same time, a composite conductive system of silver-coated copper powder and flake silver powder is introduced. By using the low cost of silver-coated copper powder and the high conductivity of flake silver powder, the silver consumption is reduced while maintaining the conductive performance.

[0022] On this basis, this application selects the combination of polyurethane resin and blocked isocyanate curing agent to form a low-temperature curing system. Through the flexibility of polyurethane and the low-temperature reaction activity of the curing agent, the problem of damage to the epoxy substrate caused by high-temperature sintering of traditional silver paste is solved, and the vibration fatigue resistance of the coating is improved. The introduction of functional additives further optimizes the dispersibility, adhesion and weather resistance, and overall achieves the balance of low cost, high conductivity and extreme environment adaptability.

[0023] 2. This application introduces nano silver particles into the conductive phase. By filling the gaps between micron-level silver-coated copper powder and flake silver powder with nano particles, a multi-scale conductive network is formed. The high specific surface area and surface activity of nano silver can reduce the contact resistance between micron-level particles and at the same time enhance the mechanical strength of the coating. In addition, the addition of nano silver reduces the risk of oxidation exposure of silver-coated copper powder, and improves the conductive stability through the "micro-nano" synergistic effect.

[0024] 3. The functional additive defined in this application is a synergistic combination of tetraethyl titanate and a phosphoric acid polyester dispersant. As a coupling agent, tetraethyl titanate forms a titanate layer on the surface of silver powder through hydrolysis and condensation reactions, enhancing the interfacial bonding force between inorganic particles and polyurethane resin; the phosphoric acid polyester dispersant prevents silver powder agglomeration through electrostatic repulsion and steric hindrance effects. The two work together to improve the dispersion uniformity of the slurry, the compactness of the coating, and the long-term stability, while reducing the porosity of the cured coating and further enhancing the conductivity. Detailed implementation mode

[0025] The following further elaborates on this application in conjunction with examples.

[0026] Example 1 A low-solid-content and high-conductivity silver paste for wind power generation includes the following components by percentage: 20% silver-coated copper powder, 2% flaky silver powder, 2% nano-silver powder, 8% polymer resin, 3% additive, and 65% organic solvent. Among them, the average particle size of the silver-coated copper powder is 6 μm, the tapped density is 1.7 g / ml, and the weight percentage of silver in the silver-coated copper powder is 30-39%; the flaky silver powder (particle size 2.5-4.5 μm), and the nano-silver particles (particle size 150-400 nm). The polymer resin is polyurethane resin. Among the additives, the addition amounts of the dispersant phosphoric acid polyester and tetraethyl titanate are 2% and 1% respectively. The organic solvent is a mixed solvent of a dibasic acid ester and propylene glycol methyl ether acetate, where the mass ratio of the dibasic acid ester to propylene glycol methyl ether acetate is 7:1; among the dibasic acid esters, the mass ratio of dimethyl succinate, dimethyl glutarate, and dimethyl adipate is 6:20:2. The preparation method of the antioxidant silver copper paste in this example includes the following steps: (1) First, add the polymer resin and the organic solvent together into a dissolution kettle. The temperature of the dissolution kettle is 80 °C, the stirring speed is 3000 r / min, and stir for 2 h until the polymer resin is completely dissolved in the organic solvent, and then filter and remove impurities with a 200-mesh polyester screen to obtain the organic carrier. (2) Ball-mill the conductive powder for 1 h at 300 r / min.

[0027] Preparation of the silver paste: Add the carrier prepared in step (1) and other components according to the weight percentages in the formula into a high-speed disperser, with a dispersion speed of 3000 r / min and disperse for 30 min until it is uniformly dispersed without a powdery particle feeling. After sufficient dispersion, a uniform silver paste is obtained. (3) Production of silver paste: Add the silver paste and dispersant obtained in step (2) to the first sand mill. The diameter of the balls is 0.8 μm. The sand mill grinds for 1 h at 3000 r / min until the fineness is less than 6 μm. Then add it to the second sand mill. The diameter of the balls is 0.2 μm. The sand mill grinds for 1 h at 3000 r / min until the fineness is less than 3 μm. Filter through a 200-mesh sieve, and fine-tune the viscosity of the silver paste by adding an appropriate amount of organic solvent so that the viscosity of the silver paste is 500 cp, thus obtaining a low-solid-content silver paste for wind turbine blades.

[0028] Example 2 A low-solid-content and high-conductivity silver paste for wind power generation includes the following components by percentage: 22% silver-coated copper powder, 2% flake silver powder, 2% nano silver powder, 8% polymer resin, 3% additive, and 63% organic solvent. Among them, the average particle size of the silver-coated copper powder is 6 μm, the tapped density is 1.7 g / ml, and the weight percentage of silver in the silver-coated copper powder is 30 - 39%; the flake silver powder (particle size 2.5 - 4.5 μm), nano silver particles (particle size 150 - 400 nm) The polymer resin is polyurethane resin. Among the additives, the addition amounts of the dispersant phosphoric acid polyester and tetraethyl titanate are 2% and 1% respectively. The organic solvent is a mixed solvent of dibasic acid ester and propylene glycol methyl ether acetate. Among them, the mass ratio of dibasic acid ester to propylene glycol methyl ether acetate is 7:1; among the dibasic acid esters, the mass ratio of dimethyl succinate, dimethyl glutarate, and dimethyl adipate is 6:20:2. The preparation method of the antioxidant silver copper paste in this example includes the following steps: (1) First, add the polymer resin and the organic solvent together to the dissolving kettle. The temperature of the dissolving kettle is 80°C, the stirring speed is 3000 r / min, and stir for 2 h until the polymer resin is completely dissolved in the organic solvent. Then filter and remove impurities with a 200-mesh polyester screen to obtain the organic carrier. (2) Ball-mill the conductive powder for 1 h at 300 r / min.

[0029] Preparation of silver paste: Add the carrier obtained in step (1) and other components according to the weight percentages in the formula to a high-speed disperser. The dispersion speed is 3000 r / min, and disperse for 30 min until it is evenly dispersed without a powdery particle feeling. After sufficient dispersion, a uniform silver paste is obtained. (3) Production of silver paste: Add the silver paste and dispersant obtained in step (2) to the first sand mill. The diameter of the balls is 0.8 μm. The sand mill is run at 3000 r / min for 1 h until the fineness is less than 6 μm. Then add it to the second sand mill. The diameter of the balls is 0.2 μm. The sand mill is run at 3000 r / min for 1 h until the fineness is less than 3 μm. Filter through a 200-mesh sieve, and fine-tune the viscosity of the silver paste by adding an appropriate amount of organic solvent to make the viscosity of the silver paste 500 cp, thus obtaining the low-solid-content silver paste for wind turbine blades.

[0030] Example 3 A low-solid-content and high-conductivity silver paste for wind power generation comprises the following components by percentage: 20% silver-coated copper powder, 4% flaky silver powder, 4% nano-silver powder, 9% polymer resin, 3% additives, and 60% organic solvent. Among them, the average particle size of the silver-coated copper powder is 6 μm, the tapped density is 1.7 g / ml, and the weight percentage of silver in the silver-coated copper powder is 30 - 39%; the flaky silver powder (particle size 2.5 - 4.5 μm), nano-silver particles (particle size 150 - 400 nm) The polymer resin is polyurethane resin. Among the additives, the addition amounts of the dispersant phosphoric acid polyester and tetraethyl titanate are 2% and 1% respectively. The organic solvent is a mixed solvent of dibasic acid ester and propylene glycol methyl ether acetate. Among them, the mass ratio of dibasic acid ester to propylene glycol methyl ether acetate is 7:1; among the dibasic acid esters, the mass ratio of dimethyl succinate, dimethyl glutarate, and dimethyl adipate is 6:20:2. The preparation method of the antioxidant silver copper paste in this example includes the following steps: (1) First, add the polymer resin and the organic solvent together to a dissolution kettle. The temperature of the dissolution kettle is 80 °C, the stirring speed is 3000 r / min, and stir for 2 h until the polymer resin is completely dissolved in the organic solvent. Then filter to remove impurities with a 200-mesh polyester mesh to obtain the organic carrier. (2) Ball-mill the conductive powder for 1 h at 300 r / min.

[0031] Preparation of silver paste: Add the carrier obtained in step (1) and other components according to the weight percentages in the formula to a high-speed disperser. The dispersion speed is 3000 r / min, and disperse for 30 min until it is evenly dispersed without a powdery particle feeling. After sufficient dispersion, a uniform silver paste is obtained. (3) Production of silver paste: Add the silver paste and dispersant obtained in step (2) to the first sand mill. The diameter of the balls is 0.8 μm. The sand mill grinds for 1 h at 3000 r / min until the fineness is less than 6 μm. Then add it to the second sand mill. The diameter of the balls is 0.2 μm. The sand mill grinds for 1 h at 3000 r / min until the fineness is less than 3 μm. Filter through a 200-mesh sieve. Fine-tune the viscosity of the silver paste by adding an appropriate amount of organic solvent so that the viscosity of the silver paste is 500 cp, thus obtaining the low-solid-content silver paste for wind turbine blades.

[0032] Example 4 A low-solid-content and high-conductivity silver paste for wind power generation includes the following components by percentage: 20% silver-coated copper powder, 2% flaky silver powder, 6% nano silver powder, 9% polymer resin, 3% additive, and 60% organic solvent. Among them, the average particle size of the silver-coated copper powder is 6 μm, the tapped density is 1.7 g / ml, and the weight percentage of silver in the silver-coated copper powder is 30 - 39%; flaky silver powder (particle size 2.5 - 4.5 μm), nano silver particles (particle size 150 - 400 nm) The polymer resin is polyurethane resin. Among the additives, the addition amounts of the dispersant phosphoric acid polyester and tetraethyl titanate are 2% and 1% respectively. The organic solvent is a mixed solvent of dibasic acid ester and propylene glycol methyl ether acetate. Among them, the mass ratio of dibasic acid ester to propylene glycol methyl ether acetate is 7:1; among the dibasic acid esters, the mass ratio of dimethyl succinate, dimethyl glutarate, and dimethyl adipate is 6:20:2. The preparation method of the antioxidant silver copper paste in this example includes the following steps: (1) First, add the polymer resin and the organic solvent together to a dissolution kettle. The temperature of the dissolution kettle is 80°C, the stirring speed is 3000 r / min, and stir for 2 h until the polymer resin is completely dissolved in the organic solvent. Then filter and remove impurities with a 200-mesh polyester screen to obtain the organic carrier. (2) Ball-mill the conductive powder for 1 h at 300 r / min.

[0033] Preparation of silver paste: Add the carrier obtained in step (1) and other components according to the weight percentages in the formula to a high-speed disperser. The dispersion speed is 3000 r / min, and disperse for 30 min until it is evenly dispersed without a powdery particle feeling. After sufficient dispersion, a uniform silver paste is obtained. (3) Production of silver paste: Add the silver paste and dispersant obtained in step (2) into the first sand mill with balls having a diameter of 0.8 μm. The sand mill is run at 3000 r / min for 1 h until the fineness is less than 6 μm. Then add it into the second sand mill with balls having a diameter of 0.2 μm. The sand mill is run at 3000 r / min for 1 h until the fineness is less than 3 μm. Filter through a 200-mesh sieve, and fine-tune the viscosity of the silver paste by adding an appropriate amount of organic solvent to make the viscosity of the silver paste 500 cp, thus obtaining the low-solid-content silver paste for wind turbine blades.

[0034] Example 5 A low-solid-content and high-conductivity silver paste for wind power generation comprises the following components by percentage: 20% silver-coated copper powder, 4% flaky silver powder, 4% nano-silver powder, 9% polymer resin, 3% additive, and 60% organic solvent. Among them, the average particle size of the silver-coated copper powder is 6 μm, the tapped density is 1.7 g / ml, and the weight percentage content of silver in the silver-coated copper powder is 30 - 39%; the flaky silver powder (particle size 2.5 - 4.5 μm), nano-silver particles (particle size 150 - 400 nm) The polymer resin is polyurethane resin. In the additive, the addition amount of the dispersant phosphoric acid polyester is 3% respectively. The organic solvent is a mixed solvent of dibasic acid ester and propylene glycol methyl ether acetate, wherein the mass ratio of dibasic acid ester to propylene glycol methyl ether acetate is 7:1; in the dibasic acid ester, the mass ratio of dimethyl succinate, dimethyl glutarate, and dimethyl adipate is 6:20:2. The preparation method of the antioxidant silver-copper paste in this example includes the following steps: (1) First, add the polymer resin and the organic solvent into a dissolution kettle. The temperature of the dissolution kettle is 80°C, the stirring speed is 3000 r / min, and stir for 2 h until the polymer resin is completely dissolved in the organic solvent. Then filter to remove impurities with a 200-mesh polyester mesh to obtain the organic carrier. (2) Ball-mill the conductive powder for 1 h at 300 r / min.

[0035] Preparation of silver paste: Add the carrier obtained in step (1) and other components according to the weight percentages in the formula into a high-speed disperser. The dispersion speed is 3000 r / min, and disperse for 30 min until it is evenly dispersed without a powdery particle feeling. After sufficient dispersion, a uniform silver paste is obtained. (3) Production of silver paste: Add the silver paste and dispersant obtained in step (2) to the first sand mill. The diameter of the balls is 0.8 μm. The sand mill is run at 3000 r / min for 1 h until the fineness is less than 6 μm. Then add it to the second sand mill. The diameter of the balls is 0.2 μm. The sand mill is run at 3000 r / min for 1 h until the fineness is less than 3 μm. Filter through a 200-mesh sieve. Fine-tune the viscosity of the silver paste by adding an appropriate amount of organic solvent to make the viscosity of the silver paste 500 cp, thus obtaining the low-solid-content silver paste for wind turbine blades.

[0036] Example 6 A low-solid-content and high-conductivity silver paste for wind power generation includes the following components by percentage: 20% silver-coated copper powder, 4% flaky silver powder, 4% nano silver powder, 9% polymer resin, 3% additive, and 60% organic solvent. Among them, the average particle size of the silver-coated copper powder is 6 μm, the tapped density is 1.7 g / ml, and the weight percentage of silver in the silver-coated copper powder is 30 - 39%; the flaky silver powder (particle size 2.5 - 4.5 μm), nano silver particles (particle size 150 - 400 nm) The polymer resin is polyurethane resin. In the additive, the addition amount of tetraethyl titanate is 3% respectively. The organic solvent is a mixed solvent of dibasic acid ester and propylene glycol methyl ether acetate. Among them, the mass ratio of dibasic acid ester to propylene glycol methyl ether acetate is 7:1; in the dibasic acid ester, the mass ratio of dimethyl succinate, dimethyl glutarate and dimethyl adipate is 6:20:2. The preparation method of the antioxidant silver-copper paste in this example includes the following steps: (1) First, add the polymer resin and the organic solvent together to a dissolution kettle. The temperature of the dissolution kettle is 80 °C, the stirring speed is 3000 r / min, and stir for 2 h until the polymer resin is completely dissolved in the organic solvent. Then filter through a 200-mesh polyester mesh to remove impurities, thus obtaining the organic carrier; (2) Ball-mill the conductive powder for 1 h at 300 r / min.

[0037] Preparation of silver paste: Add the carrier obtained in step (1) and other components according to the weight percentages in the formula to a high-speed disperser. The dispersion speed is 3000 r / min, and disperse for 30 min until it is evenly dispersed without a powdery particle feeling. After sufficient dispersion, a uniform silver paste is obtained; (3) Production of silver paste: Add the silver paste and dispersant obtained in step (2) into the first sand mill with balls having a diameter of 0.8 μm. The sand mill grinds for 1 h at 3000 r / min until the fineness is less than 6 μm. Then add it to the second sand mill with balls having a diameter of 0.2 μm. The sand mill grinds for 1 h at 3000 r / min until the fineness is less than 3 μm. Filter through a 200-mesh sieve and slightly adjust the viscosity of the silver paste by adding an appropriate amount of organic solvent to make the viscosity of the silver paste 500 cp, thus obtaining the low-solid-content silver paste for wind turbine blades.

[0038] Comparative example Comparative example 1 Select JC-2110 conductive ink, coat it on a PET film with a thickness of 10 μm, and dry it at 80 °C for 30 min to measure the adhesion and resistivity.

[0039] Comparative example 2 Select 01L-2211D silver paste, coat it on a PET film with a thickness of 10 μm, and dry it at 80 °C for 30 min to measure the adhesion and resistivity. The market price is 6000 yuan / kg.

[0040] Performance test For the low-solid-content silver paste for wind turbine blades prepared in Examples 1-6 and Comparative examples 1-2, coat it on a PET film, adjust the coating thickness to 10 μm, and dry it at 80 °C for 30 min to measure the adhesion and resistivity. The specific test results are shown in Table 1 below: Table 1 Performance detection table

[0041] From Table 1 and the technical solutions of Examples 1-6 and Comparative examples 1-2, it can be seen that the resistivity of the silver-coated copper paste prepared in this application is in the same order of magnitude as that of the pure silver paste, and the conductivity is several orders of magnitude better than that of the carbon paste ink. Therefore, it has better performance and is safer in later wind turbine blades. The price is one-third of that of the pure silver paste, and the cost is lower.

[0042] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

[0043] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0044] When this specification uses prefixes such as "known to those skilled in the art", "prior art", or similar terms to introduce materials, substances, methods, steps, devices, or components, etc., the objects introduced by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become recognized in the art as suitable for similar purposes.

[0045] In the context of this specification, any matter or thing not mentioned, except for what is expressly stated, shall directly apply those known in the art without any change.

Claims

1. A low solid content and high conductivity silver paste for wind power generation, characterized in that, Comprising the following substances in parts by weight: 20 - 50 parts of conductive material; 3 - 5 parts of blocked isocyanate curing agent; 3 - 10 parts of polyurethane; 58 - 70 parts of solvent; 1 - 5 parts of functional additive; The conductive material includes silver-coated copper powder and flaky silver powder.

2. The low-solid-content and high-conductive silver paste for wind power generation according to claim 1, wherein The organic solvent includes a mixed solvent of dibasic acid ester and propylene glycol methyl ether acetate; the dibasic acid ester is composed of dimethyl succinate, dimethyl glutarate and dimethyl adipate mixed in a mass ratio of (5 - 6):(18 - 20):(1 - 2).

3. A low solid content and high conductivity silver paste for wind power generation according to claim 1, characterized in that The conductive material also includes 2 - 5 parts by weight of nano silver particles.

4. A low-solid-content and high-conductive silver paste for wind power generation according to claim 3, characterized in that, The particle size of the silver-coated copper powder is 5 - 6μm, the particle size of the flaky silver powder is 2.5 - 4.5μm, and the particle size of the nano silver particles is 150 - 400nm.

5. A low solid content and high conductivity silver paste for wind power generation according to claim 2, characterized in that, The mixing ratio of the dibasic acid ester and propylene glycol methyl ether acetate is (6 - 7):

1.

6. The low-solid-content and high-conductive silver paste for wind power generation according to claim 1, wherein The functional additive includes tetraethyl titanate and phosphoric acid polyester dispersant mixed in a mass ratio of (1 - 2):(0.5 - 2.0).

7. The preparation method of the low solid content and high conductivity silver paste for wind power generation according to any one of claims 1-6, characterized in that, Comprising the following preparation steps: S1. Pretreatment of conductive phase: Mix the silver-coated copper powder, flaky silver powder and nano silver particles through a ball milling process, control the particle size distribution of the mixed powder to be 0.5 - 3μm, and collect to obtain the conductive phase; S2. Synthesis of organic carrier: Dissolve the polyurethane resin in an organic solvent at 80 - 85°C, stir until completely dissolved and then filter to collect the organic carrier; S3. Preparation of slurry: Mix the conductive phase, tetraethyl titanate and the organic carrier, add the phosphoric acid polyester dispersant after high-speed dispersion, and use a series of sand grinding treatments to grind to a fineness of ≤5μm; S4. Viscosity adjustment: Add solvent to adjust the viscosity to 500 - 1000cp, and prepare the low-solid-content and high-conductivity silver paste for wind power generation after vacuum degassing.

8. The preparation method of the low-solid-content and high-conductive silver paste for wind power generation according to claim 7, wherein The series of sand grinding treatment in step S3 includes the following steps: First, use zirconium beads with a diameter of 0.8 - 1.0mm and grind at 2500 - 3000r / min to a fineness of ≤6μm; then use zirconium beads with a diameter of 0.2 - 0.5mm and grind at 3000 - 3500r / min to a fineness of ≤3μm.

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