Black conductive silver paste for engineering vehicle glass and preparation method therefor

Abstract

A black conductive silver paste for engineering vehicle glass and a preparation method therefor. The raw materials of the black conductive silver paste comprise, in percentages by weight: 55-85% of a metallic silver powder, 3-6% of carbon black, 3-6% of a low-melting-point glass powder, 1-8% of a polymer resin, 1-2% of an organic additive, and 10-30% of an organic solvent. The black conductive silver paste for engineering vehicle glass is prepared by means of the steps of material preparation, organic carrier preparation, conductive silver paste preparation, black silver paste production, etc. Compared with the prior art, the addition of the carbon black, the choice of the low-melting-point glass and the choices and combination of different metallic silver micropowders jointly improve a sintering effect of the conductive silver paste on engineering vehicle glass. The prepared black conductive silver paste can not only meet the requirements of existing 8-mm-thick engineering vehicle glass for the technical indexes of sintering process performance, compatibility with a black glaze, etc., but can also meet requirements for the indexes of conductivity, weldability, tin surface color, etc.

Description

Black conductive silver paste for engineering vehicle glass and preparation method thereof Technical Field

[0001] The present invention belongs to the technical field of engineering vehicle glass, and in particular relates to a black conductive silver paste for engineering vehicle glass and a preparation method thereof. Background Art

[0002] With the development of China's high-quality economy and the advancement of the Belt and Road Initiative, my country's automotive industry, including engineering vehicles, has also achieved healthy and rapid growth. At the same time, customers' technical requirements and quality innovations for engineering vehicle glass are becoming increasingly higher.

[0003] Construction vehicle glass is typically thickened and tempered. The tempering process involves heating the glass in a furnace to near its softening point of 650-720°C. It is then rapidly cooled using cooling equipment and air cooling media. This creates compressive stress on the glass surface and tensile stress within it, improving its tensile strength, strength, and heat resistance. When tempered glass breaks, the outer layer protects it, holding it together or forming a cluster of cracks, resulting in particles approximately 10mm thick with no sharp edges.

[0004] The production process for construction vehicle glass includes: glass sheet → cutting → edging → cleaning → screen printing of black glaze and silver paste → tempering → cooling → tongue welding → packaging. Black glaze is a black glass enamel, printed on construction vehicle glass for privacy protection, decorative purposes, installation reinforcement, and UV protection.

[0005] Currently, the majority of conductive silver pastes used in domestic passenger car glass, appliance glass, coated glass, and bus glass (typically 2-5mm thick) are domestically produced, with a very small number using foreign products such as DuPont, Flow, and Johnson Matthey. Chinese patent CN 109785991 A discloses an antioxidant silver paste for bus windshields and its preparation method. The raw materials use the following components and weight percentages: 60-80% metallic silver powder; 3-6% glass powder; 2-8% polymer resin; 0.5-1.5% organic additives; 0.5-4.5% inorganic additives; and 10-30% organic solvent. The antioxidant silver paste for bus windshields is prepared through the following steps: preparing the materials, preparing the carrier, preparing the silver paste, and producing the silver paste. Chinese patent CN116665949A discloses a conductive silver paste for automotive coated glass and its preparation method. The paste contains the following components by weight: 50-80% mixed flaky silver powder; 5-10% spherical silver powder; 2-10% organic resin; 8-45% organic solvent; and 0.5-2% organic additives. While this prior art meets the technical requirements for conductivity, adhesion, tin surface color, and compatibility with black glaze for existing automotive glass, the silver layer of the conductive silver paste still reflects a significant amount of heat during the sintering process, affecting the sintering effect and overall quality of the glass. This makes it unsuitable for 8mm thick engineering vehicle glass.

[0006] Therefore, the sintering effect of glass containing conductive silver paste still needs to be improved to meet the requirements of the process and use of 8mm thick engineering vehicle glass.

[0007] Summary of the Invention

[0008] The purpose of the present invention is to provide a black conductive silver paste for engineering vehicle glass and a preparation method thereof, so as to overcome the problem of poor sintering effect of conductive silver paste glass and meet the process and use requirements of 8mm thick engineering vehicle glass.

[0009] The purpose of the present invention can be achieved by the following technical solutions:

[0010] A black conductive silver paste for engineering vehicle glass, the raw materials are the following components and weight percentages:

[0011] Metallic silver powder 55-85%; carbon black 3-6%; low melting point glass powder 3-6%; polymer resin 1-8%; organic additives 1-2%; organic solvent 10-30%.

[0012] Furthermore, the metallic silver powder includes one or more of silver micropowder 1#, silver micropowder 2# or silver micropowder 3#.

[0013] Furthermore, the average particle size of the silver micropowder 1# is 2.2-2.8 μm, the tap density is 3.5-4.5 g / ml, and the bulk density is 2.0-2.6 g / ml.

[0014] Furthermore, the average particle size of the silver micropowder 2# is 1.8-2.2 μm, the tap density is 3.0-3.5 g / ml, and the bulk density is 1.0-1.6 g / ml.

[0015] Furthermore, the average particle size of the silver micropowder 3# is 1.5-2.0 μm, the tap density is 2.5-3.0 g / ml, and the bulk density is 1.0-1.4 g / ml.

[0016] Furthermore, the carbon black has a primary particle size of 10-30 nm and a specific surface area of ​​100-250 m 2 / g.

[0017] Furthermore, the carbon black includes one or more of ORION AROSPERSE 11, CABOT R660R or BIRLA RAVEN5000 ULTRAII.

[0018] Furthermore, the low-melting-point glass powder is lead-free glass powder, which includes the following components and their weight percentages: Bi2O3 55-75%, B2O3 10-30%, ZnO 5-15%, SiO2 3-10%, Al2O3 0-3%, Na2O 0-3%, Fe2O3 0-1%, and ZrO2 0-1%.

[0019] Furthermore, the average particle size of the low-melting-point glass powder is 1.5-2.5 μm.

[0020] Furthermore, the thermal expansion coefficient of the low melting point glass powder is (70-90)×10 -7 / K.

[0021] Furthermore, the sintering temperature of the low-melting-point glass powder is 550-650°C.

[0022] Furthermore, the polymer resin includes one or more of ethyl cellulose, acrylic resin, nitro cellulose, ethyl hydroxyethyl cellulose, and wood rosin, preferably ethyl cellulose.

[0023] Furthermore, the organic additives include dispersants, plasticizers and defoamers.

[0024] Furthermore, the dispersant includes one or more of ED120, ED420 or KD16.

[0025] Furthermore, the plasticizer includes one or more of dibutyl phthalate (DBP), tributyl citrate (TBC) or dioctyl phthalate (DOP).

[0026] Furthermore, the defoaming agent includes one or more of an organosilicon defoaming agent or a non-organosilicon defoaming agent, preferably one or more of BYK333, BYK354 or BYK052N.

[0027] Furthermore, the organic solvent includes one or more of terpineol, diethylene glycol dibutyl ether, diethylene glycol butyl ether, butyl carbitol acetate, dipropylene glycol monomethyl ether or tripropylene glycol monomethyl ether.

[0028] The present invention also provides a method for preparing black conductive silver paste for engineering vehicle glass, comprising the following steps:

[0029] (1) Prepare the materials according to the following components and weight percentages:

[0030] Metallic silver powder 55-85%; carbon black 3-6%; low melting point glass powder 3-6%; polymer resin 1-8%; organic additives 1-2%; organic solvent 10-30%;

[0031] (2) Preparation of organic carrier: Weigh the polymer resin and organic solvent, heat until the polymer resin is completely dissolved, and then filter and remove impurities to obtain the organic carrier;

[0032] (3) Preparation of conductive silver paste: adding an organic additive to the organic carrier obtained in step (2), stirring evenly, further weighing metallic silver powder, carbon black, and low-melting-point glass powder and mixing them thoroughly, and then dispersing them using a disperser to obtain a uniform black paste;

[0033] (4) Production of black silver paste: The above black paste is ground in a three-roll mill to prepare a black conductive silver paste for engineering vehicle glass.

[0034] Furthermore, in step (2), the heating temperature is 70-80° C., and the filtration is performed on a 300-400 mesh mesh.

[0035] Furthermore, in step (4), the fineness of the black conductive silver paste for engineering vehicle glass is controlled to be below 15 μm, and the viscosity is 20-30 Pa·S.

[0036] After adding carbon black to the conductive silver paste, the conductive silver paste becomes naturally black. After drying at 150-200°C for 15 minutes, the silver layer and silver lines remain black. After sintering at 700-720°C for 3 minutes, the silver layer and silver lines become silvery white. This is because carbon black exhibits no performance changes at temperatures between 150 and 200°C; however, it begins to thermally decompose at 400°C, and the decomposition tends to complete at 600°C.

[0037] During the high-temperature sintering process, the ethyl cellulose in the black silver paste begins to decompose and volatilize at 250°C, while the carbon black begins to decompose and volatilize at 400°C. The low-melting-point glass powder begins to soften at 450°C, bonding with the silver powder to the glass substrate. The carbon black primarily contributes to the black color of the conductive silver paste. During the high-temperature sintering process, the silver layer, which is originally silver, reflects a large amount of heat, affecting the sintering process. The black silver layer, on the other hand, absorbs a large amount of heat, enhancing the sintering process.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The present invention improves the sintering effect of the conductive silver paste on engineering vehicle glass and reduces the sintering temperature of the conductive silver paste by adding carbon black, selecting low-melting-point glass, and selecting different combinations of metallic silver powder. The resulting black conductive silver paste not only meets the technical requirements of the sintering process performance and compatibility with black glaze of existing 8mm thick engineering vehicle glass, but also meets the requirements of conductivity, weldability, tin surface color, etc.

[0040] (2) After adding carbon black, the conductive silver paste is black in color. The black silver layer can absorb a large amount of heat and improve the degree of sintering. After sintering at 700-720°C, the carbon black completes thermal decomposition, and the color of the silver layer and silver wire remains silvery white, which will not affect the actual use of engineering vehicle glass.

[0041] (3) The metallic silver powder of the present invention uses silver micropowder. Compared with traditional flaky silver powder, silver micropowder has a smaller particle size, a spherical shape, higher activity, and is easier to sinter and form. In addition, by selecting and matching metallic silver micropowders with different particle sizes, tapped densities, and bulk densities, the sintering effect of the conductive silver paste is further improved.

[0042] (4) The low-melting-point glass powder of the present invention is mainly located between the glass substrate and the metallic silver powder, playing the role of a bonding phase, while improving the adhesion of the silver paste and the overall sintering effect of the glass. DETAILED DESCRIPTION

[0043] The embodiments of the present invention are described in detail below. The following embodiments are implemented based on the technical solutions of the present invention, and provide detailed implementation methods and specific operating processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0044] Example 1

[0045] (1) Prepare the materials according to the following components and qualities:

[0046] The metallic silver powder used was silver micropowder 1#, with an average particle size of 2.6 μm, a tap density of 4.1 g / ml, and a bulk density of 2.2 g / ml;

[0047] The carbon black used was ORION AROSPERSE 11, with a primary particle size of 19 nm, ash content of 0.1%, pH value of 8.5, and specific surface area of ​​120 m 2 / g;

[0048] The components and percentages of the low-melting-point glass powder used are: Bi2O3 65%, B2O3 18%, ZnO 9%, SiO2 45%, Al2O3 2%, Na2O 1%, Fe2O3 0.5%, ZrO2 0.5%;

[0049] The ethyl cellulose used was domestically produced N4;

[0050] The organic additives used were 0.4 g ED120, 0.2 g DBP, and 0.1 g BYK333;

[0051] (2) Preparation of organic carrier: Weigh ethyl cellulose N4 and diethylene glycol butyl ether, then heat them to 70°C and keep the temperature constant. After the polymer resin is completely dissolved, filter on a 400-mesh mesh to remove impurities, thereby obtaining an organic carrier;

[0052] (3) Preparation of conductive silver paste: First, add the weighed ED120, DBP, and BYK333 to the organic vehicle and stir evenly. Then, weigh silver micropowder 1#, carbon black AROSPERSE 11, and low-melting-point glass powder and mix them thoroughly in a mixer. Then, use a disperser to disperse them at 2000 rpm to obtain a uniform black paste.

[0053] (4) Production of black silver paste: The above black paste is ground in a three-roll mill, and the fineness of the black silver paste is controlled to 12 μm and the viscosity is controlled to 28 Pa·S by roller fine-tuning, thereby preparing a black conductive silver paste for engineering vehicle glass.

[0054] Example 2

[0055] (1) Prepare the materials according to the following components and qualities:

[0056] The metallic silver powder used was silver micropowder 2#, with an average particle size of 2.1 μm, a tap density of 3.2 g / ml, and a bulk density of 1.4 g / ml; silver micropowder 3# had an average particle size of 1.9 μm, a tap density of 2.8 g / ml, and a bulk density of 1.3 g / ml; the weight ratio of the two silver micropowders was 1:1;

[0057] The carbon black used was ORION AROSPERSE 11, with a primary particle size of 19 nm, ash content of 0.1%, pH value of 8.5, and specific surface area of ​​120 m 2 / g;

[0058] The components and percentages of the low-melting-point glass powder used are: Bi2O3 65%, B2O3 18%, ZnO 9%, SiO2 4%, Al2O3 2%, Na2O 1%, Fe2O3 0.5%, ZrO2 0.5%;

[0059] The ethyl cellulose used was domestically produced N10;

[0060] The acrylic resin used was imported VP1017F;

[0061] The organic additives used were 1 g ED420, 0.5 g DBP, and 0.5 g BYK354;

[0062] (2) Preparation of organic vehicle: Weigh ethyl cellulose N10, acrylic resin VP1017F, terpineol, and diethylene glycol butyl ether, then heat them to 80°C and maintain the temperature. After the polymer resin is completely dissolved, filter on a 400-mesh mesh to remove impurities, thereby obtaining an organic vehicle;

[0063] (3) Preparation of conductive silver paste: First, add the weighed ED420, DBP, and BYK354 to the organic vehicle and stir evenly. Then, weigh silver powder 2#, silver powder 3#, carbon black AROSPERSE 11, and low-melting-point glass powder and mix them thoroughly in a mixer. Then, use a disperser to disperse at 2000 rpm to obtain a uniform black paste.

[0064] (4) Production of black silver paste: The above black paste is ground in a three-roll mill, and the fineness of the black silver paste is controlled to 9 μm and the viscosity is controlled to 26 Pa·S by roller fine-tuning, thereby preparing a black conductive silver paste for engineering vehicle glass.

[0065] Example 3

[0066] (1) Prepare the materials according to the following components and qualities:

[0067] The metallic silver powder used is silver micropowder 1#, with an average particle size of 2.6 μm, a tap density of 4.1 g / ml, and a loose density of 2.2 g / ml; silver micropowder 2#, with an average particle size of 2.1 μm, a tap density of 3.2 g / ml, and a loose density of 1.4 g / ml; and silver micropowder 3#, with an average particle size of 1.9 μm, a tap density of 2.8 g / ml, and a loose density of 1.3 g / ml. The weight ratio of the three silver micropowders is 2:1:1.

[0068] The carbon black used was CABOT R660R, with a primary particle size of 24 nm, an ash content of 0.4%, and a specific surface area of ​​112 m 2 / g;

[0069] The components and percentages of the low-melting-point glass powder used are: Bi2O3 65%, B2O3 18%, ZnO 9%, SiO2 4%, Al2O3 2%, Na2O 1%, Fe2O3 0.5%, ZrO2 0.5%;

[0070] The ethyl cellulose used was domestically produced N10;

[0071] The organic additives used were 0.5 g ED120, 0.3 g DOP, and 0.2 g BYK052N;

[0072] (2) Preparation of organic carrier: Weigh ethyl cellulose N10, terpineol and diethylene glycol butyl ether, then heat them to 80°C and keep the temperature constant. After the polymer resin is completely dissolved, filter on a 350-mesh mesh to remove impurities, thereby obtaining an organic carrier;

[0073] (3) Preparation of conductive silver paste: First, add the weighed ED120, DOP, and BYK052N to the organic vehicle and stir evenly. Then, weigh silver powders 1#, 2#, and 3#, carbon black CABOT R660R, and low-melting-point glass powder and mix them thoroughly in a mixer. Then, use a disperser to disperse them at 2000 rpm to obtain a uniform black paste.

[0074] (4) Production of black silver paste: The above black paste is ground in a three-roll mill, and the fineness of the black silver paste is controlled to 11 μm and the viscosity is controlled to 25 Pa·S by roller fine-tuning, thereby preparing a black conductive silver paste for engineering vehicle glass.

[0075] Example 4

[0076] (1) Prepare the materials according to the following components and qualities:

[0077] The metallic silver powder used was silver micropowder 2#, with an average particle size of 2.1 μm, a tap density of 3.2 g / ml, and a bulk density of 1.4 g / ml; silver micropowder 3# had an average particle size of 1.9 μm, a tap density of 2.8 g / ml, and a bulk density of 1.3 g / ml; the weight ratio of the two silver micropowders was 1:1;

[0078] The carbon black used was CABOT R660R, with a primary particle size of 24 nm, an ash content of 0.4%, and a specific surface area of ​​112 m 2 / g;

[0079] The components and percentages of the low-melting-point glass powder used are: Bi2O3 70%, B2O3 16%, ZnO 8%, SiO2 3.5%, Al2O3 1.5%, Na2O 1.0%;

[0080] The ethyl cellulose used was domestically produced N10;

[0081] The organic additives used were 1 g KD16, 0.5 g TBC, and 0.5 g BYK333;

[0082] (2) Preparation of organic carrier: Ethyl cellulose N10, nitrocellulose, butyl carbitol acetate and diethylene glycol butyl ether were weighed, and then heated to 75°C and kept at a constant temperature. After the polymer resin was completely dissolved, the mixture was filtered on a 300-mesh mesh to remove impurities, thereby obtaining an organic carrier;

[0083] (3) Preparation of conductive silver paste: First, weighed KD16, TBC, and BYK333 were added to the organic vehicle and stirred evenly. Then, silver powder 2#, silver powder 3#, carbon black CABOT R660R, and low-melting-point glass powder were weighed and thoroughly mixed in a mixer. Then, a disperser was used to disperse the mixture at 2000 rpm to obtain a uniform black paste.

[0084] (4) Production of black silver paste: The above black paste is ground in a three-roll mill, and the fineness of the black silver paste is controlled to 10 μm and the viscosity is controlled to 27 Pa·S by roller fine-tuning, thereby preparing a black conductive silver paste for engineering vehicle glass.

[0085] Example 5

[0086] (1) Prepare the materials according to the following components and qualities:

[0087] The metallic silver powder used is silver micropowder 2#, with an average particle size of 2.1 μm, a tap density of 3.2 g / ml, and a bulk density of 1.4 g / ml;

[0088] The carbon black used was BIRLA RAVEN 5000 ULTRA II, with a primary particle size of 13 nm, a volatility of 5.0%, and a specific surface area of ​​212 m 2 / g;

[0089] The components and percentages of the low-melting-point glass powder used are: Bi2O3 70%, B2O3 16%, ZnO 8%, SiO2 3.5%, Al2O3 1.5%, Na2O 1.0%;

[0090] The ethyl cellulose used was domestically produced N7;

[0091] The organic additives used were 0.5 g KD16, 0.3 g DBP, and 0.2 g BYK354;

[0092] (2) Preparation of organic carrier: Weigh ethyl cellulose N7 and diethylene glycol butyl ether, then heat them to 80°C and keep the temperature constant. After the polymer resin is completely dissolved, filter on a 400-mesh mesh to remove impurities, thereby obtaining an organic carrier;

[0093] (3) Preparation of conductive silver paste: First, weighed KD16, DBP, and BYK354 were added to the organic vehicle and stirred evenly. Then, silver micropowder 2#, carbon black BIRLA RAVEN5000 ULTRA II, and low-melting-point glass powder were weighed and thoroughly mixed in a mixer. Then, a disperser was used to disperse the mixture at 2000 rpm to obtain a uniform black paste.

[0094] (4) Production of black silver paste: The above black paste is ground in a three-roll mill, and the fineness of the black silver paste is controlled to 13 μm and the viscosity is controlled to 24 Pa·S by roller fine-tuning, thereby preparing a black conductive silver paste for engineering vehicle glass.

[0095] Comparative Example 1:

[0096] (1) Prepare the materials according to the following components and qualities:

[0097] The metallic silver powder used was silver micropowder 1#, with an average particle size of 2.6 μm, a tap density of 4.1 g / ml, and a bulk density of 2.2 g / ml;

[0098] The carbon black used was ORION AROSPERSE 11, with a primary particle size of 19 nm, ash content of 0.1%, pH value of 8.5, and specific surface area of ​​120 m 2 / g;

[0099] The components and percentages of the low-melting-point glass powder used are: Bi2O3 65%, B2O3 18%, ZnO 9%, SiO2 4%, Al2O3 2%, Na2O 1%, Fe2O3 0.5%, ZrO2 0.5%;

[0100] The ethyl cellulose used was domestically produced N4;

[0101] The organic additives used were 0.4 g ED120, 0.2 g DBP, and 0.1 g BYK333;

[0102] (2) Preparation of organic carrier: Weigh ethyl cellulose N4 and diethylene glycol butyl ether, then heat them to 70°C and keep the temperature constant. After the polymer resin is completely dissolved, filter on a 400-mesh mesh to remove impurities, thereby obtaining an organic carrier;

[0103] (3) Preparation of conductive silver paste: First, add the weighed ED120, DBP, and BYK333 to the organic vehicle and stir evenly. Then, weigh silver micropowder 1# and low-melting-point glass powder and mix them thoroughly in a mixer. Then, use a disperser to disperse at 2000 rpm to obtain a uniform slurry.

[0104] (4) Production of silver paste: The above-mentioned slurry is ground in a three-roll mill, and the fineness of the silver paste is controlled to 12 μm by roller fine-tuning, thereby preparing a conductive silver paste.

[0105] Comparative Example 2:

[0106] (1) Prepare the materials according to the following components and qualities:

[0107] The average particle size of the silver flake powder used was 8.54 μm, the tap density was 1.78 g / mL, and the bulk density was 0.72 g / mL;

[0108] The carbon black used was ORION AROSPERSE 11, with a primary particle size of 19 nm, ash content of 0.1%, pH value of 8.5, and specific surface area of ​​120 m 2 / g;

[0109] The components and percentages of the low-melting-point glass powder used are: Bi2O3 65%, B2O3 18%, ZnO 9%, SiO2 4%, Al2O3 2%, Na2O 1%, Fe2O3 0.5%, ZrO2 0.5%;

[0110] The ethyl cellulose used was domestically produced N4;

[0111] The organic additives used were 0.4 g ED120, 0.2 g DBP, and 0.1 g BYK333;

[0112] (2) Preparation of organic carrier: Weigh ethyl cellulose N4 and diethylene glycol butyl ether, then heat them to 70°C and keep the temperature constant. After the polymer resin is completely dissolved, filter on a 400-mesh mesh to remove impurities, thereby obtaining an organic carrier;

[0113] (3) Preparation of conductive silver paste: First, add the weighed ED120, DBP, and BYK333 to the organic vehicle and stir evenly. Then, weigh silver micropowder 1# and low-melting-point glass powder and mix them thoroughly in a mixer. Then, use a disperser to disperse at 2000 rpm to obtain a uniform slurry.

[0114] (4) Production of silver paste: The above-mentioned paste is ground in a three-roll mill, and the fineness of the silver paste is controlled to 12 μm by roller fine-tuning, thereby preparing a conductive silver paste for engineering vehicle glass.

[0115] The present invention performs the following tests on Examples 1-5 and the comparative example:

[0116] The test methods and results for the product's sintering process, tin surface color, adhesion, conductivity, and compatibility with black glaze are shown in the table below:

[0117] From the above test results, it can be seen that the silver paste prepared by this method meets the requirements of the sintering process performance of the existing 8mm thick engineering vehicle glass and the matching with the black glaze, and is also excellent in conductivity, adhesion and tin surface color.

[0118] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A black conductive silver paste for engineering vehicle glass, characterized in that: The raw materials use the following components and weight percentages: Metallic silver powder 55-85%; carbon black 3-6%; low melting point glass powder 3-6%; polymer resin 1-8%; organic additives 1-2%; organic solvents 10-30%.

2. The black conductive silver paste for engineering vehicle glass according to claim 1, characterized in that: The metal silver powder includes one or more of silver micropowder 1#, silver micropowder 2# or silver micropowder 3#.

3. The black conductive silver paste for engineering vehicle glass according to claim 2, characterized in that: The average particle size of the silver micropowder 1# is 2.2-2.8 μm, the tap density is 3.5-4.5 g / ml, and the bulk density is 2.0-2.6 g / ml; The average particle size of the silver micropowder 2# is 1.8-2.2 μm, the tap density is 3.0-3.5 g / ml, and the bulk density is 1.0-1.6 g / ml; The average particle size of the silver micropowder 3# is 1.5-2.0 μm, the tap density is 2.5-3.0 g / ml, and the loose density is 1.0-1.4 g / ml.

4. The black conductive silver paste for engineering vehicle glass according to claim 1, characterized in that: The carbon black has a primary particle size of 10-30 nm and a specific surface area of ​​100-250 m 2 / g.

5. The black conductive silver paste for engineering vehicle glass according to claim 1, characterized in that: The low melting point glass powder comprises the following components and their weight percentages: Bi2O3 55-75%, B2O3 10-30%, ZnO 5-15%, SiO2 3-10%, Al2O3 0-3%, Na2O 0-3%, Fe2O3 0-1%, ZrO2 0-1%; The low melting point glass powder has an average particle size of 1.5-2.5 μm and a thermal expansion coefficient of (70-90)×10 -7 / K, the sintering temperature is 550-650℃.

6. The black conductive silver paste for engineering vehicle glass according to claim 1, characterized in that: The polymer resin includes one or more of ethyl cellulose, acrylic resin, nitro cellulose, ethyl hydroxyethyl cellulose and wood rosin.

7. The black conductive silver paste for engineering vehicle glass according to claim 1, characterized in that: The organic additives include dispersants, plasticizers and defoamers; The dispersant includes one or more of fatty acids, fatty amides or fatty acid esters; The plasticizer includes one of dibutyl phthalate, tributyl citrate or dioctyl phthalate. kind or kinds; The defoaming agent includes one or more of an organosilicon defoaming agent or a non-organosilicon defoaming agent.

8. The black conductive silver paste for engineering vehicle glass according to claim 1, characterized in that: The organic solvent includes one or more of terpineol, diethylene glycol dibutyl ether, diethylene glycol butyl ether, butyl carbitol acetate, dipropylene glycol monomethyl ether or tripropylene glycol monomethyl ether.

9. A method for preparing black conductive silver paste for engineering vehicle glass according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Prepare the materials according to the following components and weight percentages: Metallic silver powder 55-85%; carbon black 3-6%; low melting point glass powder 3-6%; polymer resin 1-8%; organic additives 1-2%; organic solvents 10-30%; (2) Preparation of organic carrier: Weigh a polymer resin and an organic solvent, heat until the polymer resin is completely dissolved, and then filter and remove impurities to obtain an organic carrier; (3) Preparation of conductive silver paste: adding an organic additive to the organic carrier obtained in step (2), stirring evenly, weighing metallic silver powder, carbon black, and low-melting-point glass powder, mixing them well, and then dispersing them using a disperser to obtain a uniform black paste; (4) Production of black silver paste: The black paste is ground in a three-roll mill to prepare a black conductive silver paste for engineering vehicle glass.

10. The method for preparing black conductive silver paste for engineering vehicle glass according to claim 9, characterized in that: In step (2), the heating temperature is 70-80° C., and the filtration is performed on a mesh of 300-400 mesh; In step (4), the fineness of the black conductive silver paste for engineering vehicle glass is controlled to be below 15 μm, and the viscosity is 20-30 Pa·S.

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