Acid-resistant anti-oxidation silver paste for automobile glass and preparation method of acid-resistant anti-oxidation silver paste

Abstract

The invention belongs to the technical field of conductive paste for automobile glass, and relates to acid-resistant antioxidant silver paste for automobile glass and a preparation method of the acid-resistant antioxidant silver paste. The silver paste comprises the following raw materials: 50-70 parts of metal silver powder, 5-15 parts of lead-free glass powder, 0.5-5 parts of rare earth salt, 2-10 parts of polymer resin, 1-3 parts of an organic additive and 10-30 parts of an organic solvent. The preparation method comprises the following steps: modifying rare earth salt by a silane coupling agent to obtain modified rare earth salt; dissolving polymer resin in an organic solvent to obtain a carrier; and adding the metal silver powder, the lead-free glass powder, the organic additive and the modified rare earth salt into the carrier, and sequentially performing stirring, grinding and vacuum defoaming treatment to obtain the acid-resistant antioxidant silver paste. The automobile rear windshield demisting heating wire is suitable for automobile rear windshield demisting heating wires, and the high-reliability welding requirement can be met.

Description

Technical Field

[0001] This invention belongs to the field of conductive paste technology for automotive glass, and relates to an acid-resistant and antioxidant silver paste for automotive glass and its preparation method. Background Technology

[0002] Conductive silver paste for automotive glass is a key material for core components such as rear window defroster heating wires and vehicle antennas, and its performance directly affects the reliability and service life of automotive electronic systems. With the popularization of new energy vehicles and special vehicles for high-altitude and cold regions, higher requirements are placed on the welding strength of silver paste. Although traditional silver paste can meet the basic requirements of acid resistance, oxidation resistance and black glaze compatibility, there are two major pain points in high-reliability welding scenarios: First, a dense oxide film (Ag2O) easily forms on the surface of the silver layer during sintering and use, resulting in insufficient bonding strength at the welding interface between the tin-plated copper wire and the silver layer, leading to incomplete soldering and desoldering, which seriously affects the conductivity stability of the heating wire; Second, the glass phase in existing silver pastes has poor wetting performance at the silver-black glaze interface, resulting in uneven solder spreading during welding, further reducing the strength of the solder joint, making it difficult to meet the long-term use requirements of new energy buses and vehicles for high-altitude and cold regions.

[0003] Meanwhile, environmental regulations are becoming increasingly stringent in requiring lead-free automotive parts, and traditional lead-containing glass powder silver paste has been gradually phased out.

[0004] Patent CN105753335A discloses an acid-resistant and antioxidant silver paste for automotive glass and its preparation method. The raw materials include 55-75% metallic silver powder, 5-15% glass powder, 2-10% polymer resin, 1-3% organic additives, and 10-30% organic solvent. The acid-resistant and antioxidant silver paste for automotive glass is prepared through steps such as material preparation, carrier preparation, silver paste preparation, and silver paste production. However, this technical solution has significant drawbacks: First, it fails to effectively address the problem of insufficient bonding strength at the welding interface caused by silver layer oxidation. During service, the silver layer is prone to interface performance degradation due to oxidation, directly affecting welding reliability and structural stability. Second, the automotive glass compatible with this silver paste uses traditional GT furnace production processes, which cannot meet the current needs of lightweight development in new energy vehicles. Third, the new generation of automotive glass has widely adopted pressing furnace processes, which impose a core requirement of low-temperature sintering on the silver paste to match the preparation characteristics of lightweight glass. The silver paste system of this patented solution cannot meet the adaptation requirements of low sintering temperature, and it is difficult to ensure that the core properties of the silver paste, such as acid resistance and oxidation resistance, do not degrade under the premise of lowering the sintering temperature, making it unsuitable for the production and application of new generation lightweight automotive glass.

[0005] Therefore, there is an urgent need to develop a new type of silver paste that combines lead-free environmental protection, high welding strength, acid and oxidation resistance, and compatibility with black glaze. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide an acid-resistant and antioxidant silver paste for automotive glass and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions: An acid-resistant and antioxidant silver paste for automotive glass, comprising the following components and their weight percentages: 50-70 parts of metallic silver powder; 5-15 parts of lead-free glass powder; 0.5 to 5 parts of rare earth salts; 2-10 parts of polymer resin; 1-3 parts organic additives; 10-30 parts organic solvent.

[0008] Furthermore, the rare earth salt is Co3(PO4)2·nH2O, n=0~4, with an average particle size D50 of 0.3~2.0μm and a specific surface area of ​​3~10m². 2 / g.

[0009] Furthermore, the rare earth salt is surface-modified with 1-5% of a silane coupling agent based on its mass before being put into use; the silane coupling agent is selected from one or both of KH560 or KH570.

[0010] Furthermore, the metallic silver powder is composed of spherical silver powder and flake silver powder; wherein the spherical silver powder has a D50 particle size of 0.5~6μm and a tap density of 2.0~4.0g / ml; the flake silver powder has a D50 particle size of 1~12μm and a tap density of 1.0~3.0g / ml, and the mass ratio of spherical silver powder to flake silver powder is (3~6):1.

[0011] Furthermore, the lead-free glass powder is a composite of glass powder-L and glass powder-M; wherein the sintering temperature of glass powder-L is 550~650℃ and the softening point is 450~520℃; the sintering temperature of glass powder-M is 650~750℃ and the softening point is 540~580℃; and the mass ratio of glass powder-L to glass powder-M is 1:(1~4).

[0012] Furthermore, the polymer resin is selected from one or more of ethyl cellulose, nitrocellulose, ethyl hydroxyethyl cellulose, or rosin.

[0013] Further, the organic additive is selected from one or more of dibutyl phthalate, organosilicon resin, dioctyl phthalate, tributyl citrate, hydrogenated castor oil, trioctyl citrate, polyvinyl butyral, and silane coupling agents. The silane coupling agent is selected from one or more of KH550, KH560, and KH570.

[0014] Furthermore, the organic solvent is selected from one or more of terpineol, diethylene glycol butyl ether, butyl carbitol acetate, tripropylene glycol monomethyl ether, or turpentine.

[0015] The present invention also provides a method for preparing acid-resistant and antioxidant silver paste for automotive glass as described in any of the preceding claims, comprising the following steps: S1. Modification of rare earth salts: Rare earth salts are added to anhydrous ethanol, dispersed evenly by ultrasonication, and then silane coupling agent is added dropwise. The mixture is refluxed at 70~90℃ for 1~2 hours, dried, and sieved to obtain modified rare earth salts. S2. Carrier synthesis: The polymer resin is dissolved in an organic solvent, filtered, and cooled to room temperature to obtain the carrier; S3. Production of silver paste: Add metallic silver powder, lead-free glass powder, organic additives and modified rare earth salt powder obtained in step S1 to the carrier obtained in step S2, and then stir, grind and vacuum degassing to obtain acid-resistant and antioxidant silver paste.

[0016] Further, in step S1, the amount of silane coupling agent added is 2-5% of the mass of the rare earth salt; the silane coupling agent is selected from one or both of KH560 and KH570; In step S2, the melting temperature is 70~90℃; In step S3, the stirring is carried out using a planetary mixer at a speed of 400~600 rpm for 10~20 min; the grinding is carried out using a three-roll mill for 4~8 passes, controlling the fineness of the resulting silver paste to be ≤10μm and the viscosity to be 20~30 Pa·s (25℃, 10 rpm); the roller temperature of the three-roll mill is 25~35℃, the roller gap decreases progressively, and the final roller gap is ≤5μm; the vacuum degassing condition is to degas under a vacuum of -0.08~-0.1MPa for 5~15 min.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The automotive glass silver paste provided by the present invention has high welding strength, acid resistance, oxidation resistance and black glaze compatibility, and can be directly industrialized and prepared, making it highly practical.

[0018] (2) This invention is the first to use environmentally friendly rare earth salt Co3(PO4)2 as a functional filler in automotive glass silver paste. During the sintering process at 520~680℃, the rare earth salt can decompose to generate CoO and P2O5. The two work together to optimize the performance of the silver layer: CoO can reduce the oxygen partial pressure on the surface of the silver layer, effectively inhibit the generation of Ag2O, and improve the oxidation resistance of the silver layer; P2O5 can react with the glass network, reduce the interfacial tension, promote solder wetting, and lay the foundation for improving the welding strength.

[0019] (3) The silver paste of the present invention is screen-printed onto the black glaze surface of automotive glass. After rapid tempering at 650~720℃ for 3~5 minutes, a silver layer with a thickness of 8~15μm can be formed, and the core performance indicators are excellent: Significantly improved welding strength: Tin-plated copper wire with a 2×2mm pad and 360℃ immersion welding for 3 seconds has a welding strength ≥180N; Strong acid resistance: After immersion in 0.1 mol / L H2SO4 solution for 2 hours, the silver layer showed no peeling or damage; Excellent oxidation resistance: After aging at 85℃ / 85% RH for 1000 hours, the silver layer resistance change rate is ≤5%, and the resistance stability is good; Appearance and matching meet the standards: the tin surface is reddish-brown (ΔE < 0.5, compared with the standard color card), the black glaze has good matching, and there are no defects such as yellow edges or bubbles.

[0020] (4) The silver paste of this invention meets the mainstream industry standards such as Volkswagen TL-211 and GMW3091 in terms of its acid resistance, oxidation resistance, electrical stability, appearance color, and black glaze compatibility, and is suitable for the stringent requirements of automotive glass production. Meanwhile, the amount of rare earth salts in the silver paste is low (≤5%), increasing production costs by only <2%, requiring no major modifications to existing production lines, facilitating rapid mass production switching, and possessing significant economic value and promising prospects for widespread application. This silver paste is suitable for automotive rear windshield defogger heating lines and can meet the requirements for high-reliability welding. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0022] Unless otherwise specified, all raw materials used in this invention are commercially available products.

[0023] Example 1 An acid-resistant and antioxidant silver paste for automotive glass, comprising the following components and contents: Spherical silver powder: 60g, D50=2.8μm, tap density 3.8g / ml; Flake silver powder: 10g, D50=6μm, tap density 2.4g / ml; Glass powder - L: 1g, sintering temperature 580℃, softening point 450℃; Glass powder-M: 4g, sintering temperature 650℃, softening point 560℃; Rare earth salt Co3(PO4)2·4H2O: 2g, D50=0.8μm, specific surface area 4.8m² 2 / g; Ethyl cellulose: 2g; Organic additive: 1g, composed of 0.5g dibutyl phthalate, 0.25g organosilicon resin and 0.25g silane coupling agent KH550; Solvent: 17g of terpineol; The specific preparation steps of the acid-resistant and antioxidant silver paste for automotive glass in this embodiment are as follows: S1. Modification of rare earth salts: Add 2g of rare earth salt to 15g of anhydrous ethanol, disperse evenly by ultrasonication, then add 0.02g of silane coupling agent KH560 dropwise, reflux at 80℃ for 2h, dry by rotary evaporation, and pass through a 500-mesh sieve to obtain modified rare earth salts. S2. Support synthesis: Ethyl cellulose was added to terpineol, stirred and dissolved at 80°C, filtered and cooled to room temperature to obtain the support; S3. Preparation of silver paste: Spherical silver powder, flake silver powder, glass powder-L, glass powder-M, organic additives, and modified rare earth salt obtained in step S1 are added to the carrier obtained in step S2. The mixture is first placed in a planetary mixer and stirred at 500 rpm for 15 min. Then it is transferred to a three-roll mill for grinding 5 times (the roller temperature of the three-roll mill is controlled at 25~35℃, and the roller gap is adjusted by progressively decreasing the roller gap, with the final roller gap being 4μm). The fineness of the resulting silver paste is controlled to be 8μm and the viscosity to be 25Pa·s (test conditions: 25℃, 10rpm). Finally, it is degassed under a vacuum of -0.09MPa for 10 min to obtain acid-resistant and antioxidant silver paste.

[0024] Example 2 An acid-resistant and antioxidant silver paste for automotive glass, comprising the following components and contents: Spherical silver powder: 55g, D50=2.3μm, tap density 3.2g / ml; Flake silver powder: 10g, D50=6μm, tap density 2.4g / ml; Glass powder - L: 3g, sintering temperature 580℃, softening point 450℃; Glass powder-M: 7g, sintering temperature 660℃, softening point 560℃; Rare earth salt Co3(PO4)2·2H2O: 3g, D50=0.9μm, specific surface area 5.5m² 2 / g; Nitrocellulose: 5g; Organic additive: 1g, composed of 0.6g dioctyl phthalate, 0.25g organosilicon resin and 0.15g silane coupling agent KH560; Solvent: 19g of diethylene glycol butyl ether; The specific preparation steps of the acid-resistant and antioxidant silver paste for automotive glass in this embodiment are as follows: S1. Modification of rare earth salts: Add 3g of rare earth salt to 20g of anhydrous ethanol, disperse evenly by ultrasonication, then add 0.06g of silane coupling agent KH560 dropwise, reflux at 80℃ for 2h, dry by rotary evaporation, and pass through a 400-mesh sieve to obtain modified rare earth salts. S2. Support synthesis: Nitrocellulose was added to diethylene glycol butyl ether, stirred and dissolved at 80°C, filtered and cooled to room temperature to obtain the support; S3. Preparation of silver paste: Spherical silver powder, flake silver powder, glass powder-L, glass powder-M, organic additives, and modified rare earth salt obtained in step S1 are added to the carrier obtained in step S2. The mixture is first placed in a planetary mixer and stirred at 500 rpm for 15 min. Then it is transferred to a three-roll mill for grinding 7 times (the roller temperature of the three-roll mill is controlled at 25~35℃, and the roller gap is adjusted by progressively decreasing the gap, with the final roller gap being 3μm). The fineness of the resulting silver paste is controlled to be 9μm and the viscosity to be 28Pa·s (test conditions: 25℃, 10rpm). Finally, it is degassed under a vacuum of -0.09MPa for 10 min to obtain acid-resistant and antioxidant silver paste.

[0025] Example 3 An acid-resistant and antioxidant silver paste for automotive glass, comprising the following components and contents: Spherical silver powder: 45g, D50=1.8μm, tap density 2.6g / ml; Flake silver powder: 10g, D50=7.5μm, tap density 1.9g / ml; Glass powder - L: 2g, sintering temperature 580℃, softening point 450℃; Glass powder-M: 6g, sintering temperature 680℃, softening point 560℃; Rare earth salt Co3(PO4)2·4H2O: 4g, D50=0.7μm, specific surface area 4.2m² 2 / g; Ethyl hydroxyethyl cellulose: 10g; Organic additive: 2g, composed of 1g tributyl citrate, 0.8g hydrogenated castor oil and 0.2g silane coupling agent KH570; Solvent: 10g terpineol + 15g butyl carbitol acetate; The specific preparation steps of the acid-resistant and antioxidant silver paste for automotive glass in this embodiment are as follows: S1. Modification of rare earth salts: 4g of rare earth salts were added to 25g of anhydrous ethanol, and after being ultrasonically dispersed evenly, 0.06g of silane coupling agent KH570 was added dropwise. The mixture was refluxed at 75℃ for 1.5h, dried by rotary evaporation, and passed through a 400-mesh sieve to obtain modified rare earth salts. S2. Support synthesis: Ethyl hydroxyethyl cellulose was added to a solvent, stirred and dissolved at 80°C, filtered, and cooled to room temperature to obtain the support; S3. Preparation of silver paste: Spherical silver powder, flake silver powder, glass powder-L, glass powder-M, organic additives, and modified rare earth salt obtained in step S1 are added to the carrier obtained in step S2. The mixture is first placed in a planetary mixer and stirred at 500 rpm for 15 min. Then it is transferred to a three-roll mill for grinding 6 times (the roller temperature of the three-roll mill is controlled at 25~35℃, and the roller gap is adjusted by progressively decreasing the roller gap, with the final roller gap being 4μm). The fineness of the resulting silver paste is controlled to be 10μm and the viscosity to be 26Pa·s (test conditions: 25℃, 10rpm). Finally, it is degassed under a vacuum of -0.09MPa for 10 min to obtain acid-resistant and antioxidant silver paste.

[0026] Example 4 An acid-resistant and antioxidant silver paste for automotive glass, comprising the following components and contents: Spherical silver powder: 40g, D50=4.5μm, tap density 3.5g / ml; Flake silver powder: 10g, D50=8μm, tap density 2.2g / ml; Glass powder - L: 5g, sintering temperature 580℃, softening point 450℃; Glass powder-M: 10g, sintering temperature 650℃, softening point 560℃; Rare earth salt Co3(PO4)2 (anhydrous): 5g, D50 = 1.0μm, specific surface area 7.3m² 2 / g; Ethyl cellulose: 5g; Nitrocellulose: 2g; Organic additives: 3g, consisting of 1.5g trioctyl citrate, 1g polyvinyl butyral and 0.5g KH560; Solvent: 15g tripropylene glycol monomethyl ether + 10g turpentine oil; The specific preparation steps of the acid-resistant and antioxidant silver paste for automotive glass in this embodiment are as follows: S1. Modification of rare earth salts: Add 5g of rare earth salt to 30g of anhydrous ethanol, disperse evenly by ultrasonication, add 0.1g of silane coupling agent KH560 dropwise, reflux at 80℃ for 2h, dry by rotary evaporation, and pass through a 400-mesh sieve to obtain modified rare earth salts. S2. Support synthesis: Ethyl cellulose and nitrocellulose were added to a solvent, stirred and dissolved at 80°C, filtered, and cooled to room temperature to obtain the support; S3. Preparation of silver paste: Spherical silver powder, flake silver powder, glass powder-L, glass powder-M, organic additives, and modified rare earth salt obtained in step S1 are added to the carrier obtained in step S2. The mixture is first placed in a planetary mixer and stirred at 500 rpm for 15 min. Then it is transferred to a three-roll mill for grinding 7 times (the roller temperature of the three-roll mill is controlled at 25~35℃, and the roller gap is adjusted by progressively decreasing the roller gap, with the final roller gap being 3μm). The fineness of the resulting silver paste is controlled to be 8μm and the viscosity to be 30Pa·s (test conditions: 25℃, 10rpm). Finally, it is degassed under a vacuum of -0.09MPa for 10 min to obtain acid-resistant and antioxidant silver paste.

[0027] Example 5 An acid-resistant and antioxidant silver paste for automotive glass, comprising the following components and contents: Spherical silver powder: 58g, D50 = 2.5μm, tap density 3.5g / ml; Flake silver powder: 10g, D50=7μm, tap density 2.1g / ml; Glass powder - L: 5g, sintering temperature 580℃, softening point 450℃; Glass powder-M: 2g, sintering temperature 700℃, softening point 560℃; Rare earth salt Co3(PO4)2·H2O: 2.5g, D50=0.6μm, specific surface area 4.5m² 2 / g; Pine resin: 6g; Organic additives: 1.3g, composed of 0.7g trioctyl citrate, 0.4g hydrogenated castor oil and 0.2g KH570; Solvent: 15.2g of terpineol; The specific preparation steps of the acid-resistant and antioxidant silver paste for automotive glass in this embodiment are as follows: S1. Modification of rare earth salts: 2.5g of rare earth salts were added to 20g of anhydrous ethanol, and after being ultrasonically dispersed evenly, 0.025g of silane coupling agent KH560 was added dropwise. The mixture was refluxed at 75℃ for 1.5h, dried by rotary evaporation, and passed through a 400-mesh sieve to obtain modified rare earth salts. S2. Support synthesis: Pine resin is added to a solvent, stirred and dissolved at 80°C, filtered, and cooled to room temperature to obtain the support; S3. Preparation of silver paste: Spherical silver powder, flake silver powder, glass powder-L, glass powder-M, organic additives, and the modified rare earth salt obtained in step S1 are added to the carrier obtained in step S2. The mixture is first placed in a planetary mixer and stirred at 500 rpm for 15 min. Then it is transferred to a three-roll mill for grinding 6 times (the roller temperature of the three-roll mill is controlled at 25~35℃, and the roller gap is adjusted by progressively decreasing the roller gap, with the final roller gap being 4μm). The fineness of the resulting silver paste is controlled to be 9μm and the viscosity to be 21Pa·s (test conditions: 25℃, 10rpm). Finally, it is degassed under a vacuum of -0.09MPa for 10 min to obtain an acid-resistant and antioxidant silver paste.

[0028] Comparative Example 1 A silver paste, whose raw material composition and preparation method are basically the same as those in Example 1, the only difference being that: the above-mentioned rare earth salt Co3(PO4)2·4H2O is not added to the raw material, and the surface modification and addition process steps related to rare earth salt are omitted in the preparation method.

[0029] The silver pastes obtained in Examples 1-5 and Comparative Example 1 were subjected to performance testing, and the testing methods are as follows: Tempering process: The glass coated with silver paste heating wire is tempered according to the standard tempering process of the automotive glass industry. The specific process parameters are shown in Table 1. Resistance test: Using a multimeter, the tempered automotive glass silver paste heating wire was tested at room temperature (25℃). The test length was 350mm, and the two ends of the heating wire were selected for measurement to obtain the final resistance value.

[0030] Welding strength test: According to the Volkswagen TL-211 standard, 2×2mm silver paste pads were prepared. Tinned copper wire (0.8mm in diameter) was immersed in the solder for 3 seconds at 360℃. After cooling to room temperature, a peel test was performed using a handheld tensile tester. The maximum tensile force when the pad separated from the silver layer was recorded, which is the welding strength.

[0031] Acid resistance test: According to GMW3091 standard, the glass sample coated with silver paste and tempered is immersed in 0.1 mol / L H2SO4 solution and soaked at room temperature for 2 hours. During the soaking, the solution is kept still. After the test, the sample is taken out, rinsed with deionized water and dried. The silver layer is visually observed for phenomena such as peeling, flaking, and discoloration. The evaluation level is "excellent" (no peeling, flaking, or discoloration) or "poor" (the above defects exist).

[0032] Antioxidant resistance test: The sample was placed in a humid heat aging chamber, with the temperature set at 85℃ and the relative humidity at 85% RH, and aged continuously for 1000 hours. The resistance value R0 of the silver paste heating wire before aging and the resistance value R of the silver paste heating wire after aging were measured respectively. The resistance change rate was calculated according to the formula ΔR / R0×100%, where ΔR=R-R0. The resistance change rate ≤5% is considered qualified. At the same time, the presence of oxidation discoloration on the appearance of the sample was recorded.

[0033] Black glaze compatibility test: Place the glass sample coated with silver paste and tempered under natural light and visually observe whether there are any defects such as yellow edges or bubbles at the junction of the silver layer and the black glaze.

[0034] Tin surface color test: Using a colorimeter (CIE Lab color space) and the automotive glass silver paste industry standard color card as a reference, the color of the soldered tin surface is tested, and the color difference ΔE value is measured. ΔE < 0.5 is considered to meet the color requirements.

[0035] Table 1. Process parameters and performance test results of automotive glass silver paste in Examples 1-5 and Comparative Example 1. The test results above show that the welding strength of Examples 1 to 5 of the present invention is ≥180N, and Example 4 reaches a maximum of 201N, which is more than 30% higher than Comparative Example 1 (only 145N).

[0036] The silver paste of this invention has excellent comprehensive performance. All embodiments meet the following requirements: resistance ≤ 4.0Ω / 350mm, acid resistance (no peeling after soaking in 0.1mol / L H2SO4 for 2h), and oxidation resistance (resistance change rate ≤ 5% after aging at 85℃ / 85% RH for 1000h). The tin surface is reddish-brown (ΔE < 0.5), and it matches well with black glaze. It fully complies with mainstream industry standards such as Volkswagen TL-211 and GMW3091.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An acid-resistant and antioxidant silver paste for automotive glass, characterized in that, The raw materials include the following components and their weight percentages: 50-70 parts of metallic silver powder; 5-15 parts of lead-free glass powder; 0.5 to 5 parts of rare earth salts; 2-10 parts of polymer resin; 1-3 parts organic additives; 10-30 parts organic solvent.

2. The acid-resistant and antioxidant silver paste for automotive glass according to claim 1, characterized in that, Rare earth salts are Co3(PO4)2·nH2O, n=0~4, with an average particle size D50 of 0.3~2.0μm and a specific surface area of ​​3~10m². 2 / g.

3. The acid-resistant and antioxidant silver paste for automotive glass according to claim 1, characterized in that, The rare earth salt is put into use after being surface modified with 1-5% of a silane coupling agent based on its mass.

4. The acid-resistant and antioxidant silver paste for automotive glass according to claim 1, characterized in that, The metallic silver powder is composed of spherical silver powder and flake silver powder; wherein, the spherical silver powder has a D50 particle size of 0.5~6μm and a tap density of 2.0~4.0g / ml; and the flake silver powder has a D50 particle size of 1~12μm and a tap density of 1.0~3.0g / ml.

5. The acid-resistant and antioxidant silver paste for automotive glass according to claim 1, characterized in that, The lead-free glass powder is a composite of glass powder-L and glass powder-M; wherein the sintering temperature of glass powder-L is 550~650℃ and the softening point is 450~520℃; the sintering temperature of glass powder-M is 650~750℃ and the softening point is 540~580℃.

6. The acid-resistant and antioxidant silver paste for automotive glass according to claim 1, characterized in that, The polymer resin is selected from one or more of ethyl cellulose, nitrocellulose, ethyl hydroxyethyl cellulose, or rosin.

7. The acid-resistant and antioxidant silver paste for automotive glass according to claim 1, characterized in that, The organic additive is selected from one or more of the following: dibutyl phthalate, organosilicon resin, dioctyl phthalate, tributyl citrate, hydrogenated castor oil, trioctyl citrate, polyvinyl butyral, and silane coupling agent.

8. The acid-resistant and antioxidant silver paste for automotive glass according to claim 1, characterized in that, The organic solvent is selected from one or more of terpineol, diethylene glycol butyl ether, butyl carbitol acetate, tripropylene glycol monomethyl ether, or turpentine.

9. A method for preparing an acid-resistant and antioxidant silver paste for automotive glass as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Modification of rare earth salts: Rare earth salts are added to anhydrous ethanol, dispersed evenly by ultrasonication, and then silane coupling agent is added dropwise. The mixture is refluxed at 70~90℃ for 1~2 hours, dried, and sieved to obtain modified rare earth salts. S2. Carrier synthesis: The polymer resin is dissolved in an organic solvent, filtered, and cooled to room temperature to obtain the carrier; S3. Production of silver paste: Add metallic silver powder, lead-free glass powder, organic additives and modified rare earth salt obtained in step S1 to the carrier obtained in step S2, and then stir, grind and vacuum degasse to obtain acid-resistant and antioxidant silver paste.

10. The method for preparing acid-resistant and antioxidant silver paste for automotive glass according to claim 9, characterized in that, In step S1, the amount of silane coupling agent added is 2-5% of the mass of the rare earth salt; In step S2, the melting temperature is 70~90℃; In step S3, the stirring is carried out using a planetary mixer at a speed of 400~600 rpm for 10~20 min; the grinding is carried out using a three-roll mill for 4~8 passes, controlling the fineness of the resulting silver paste to be ≤10μm and the viscosity to be 20~30 Pa·s; the vacuum degassing condition is to degas under a vacuum of -0.08~-0.1MPa for 5~15 min.

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