Conductive silver paste for automotive coated glass and preparation method thereof

Abstract

The present invention relates to a conductive silver paste for automotive coated glass and a preparation method thereof, belonging to the technical field of functional glass. The conductive silver paste comprises the following components and weight contents: 50-80% of flaky mixed silver powder; 5-10% of spherical silver powder; 2-10% of organic resin; 8-45% of organic solvent; and 0.5-2% of organic additive. The preparation method comprises: firstly mixing the organic resin with the organic solvent to obtain an organic carrier; then mixing and dispersing the flaky mixed silver powder, the spherical silver powder, the organic additive, and the organic carrier to obtain the conductive silver paste. Compared with the prior art, the present invention effectively solves the problems of low resistance, adhesion, wide sintering window, and bonding strength between the silver paste and the copper foil.

Description

Technical Field

[0001] The invention belongs to the technical field of functional glass and relates to a conductive silver paste for automobile coated glass and a preparation method thereof. Background Art

[0002] Automotive glass is an important safety component of the car and also carries the appearance of the entire car. With the continuous innovation and development of technology, various high-performance automotive glass have emerged, such as panoramic skylight glass, coated glass, dimming glass, etc.

[0003] Coated glass, also known as conductive film glass, is made by evaporating a metal film on the surface of transparent glass, or spraying a metal oxide conductive film on the heated glass surface. The double-layer coated glass for the rear window required by new energy vehicles is generally printed with conductive silver paste on the two sides of the coated glass through screen printing technology. The middle area is the conductive circuit. After being treated at a high temperature of 550-750℃ in a hot bending furnace for 3-5 minutes, the conductive silver paste adheres to the surface of the coated glass to form a conductive busbar layer. The resistance of the coated glass after sintering is generally 0.5-1.2Ω. The internal power supply is connected to the silver surface on both sides of the automotive coated glass by copper foil bonding. After the voltage of 12-13V is applied, the entire coated glass begins to heat up and heats to 60-80℃, thereby achieving the effect of defogger and defrost.

[0004] At present, the conductive silver paste used for coated glass of new energy vehicles is imported silver paste, such as foreign products such as Flow from the United States. The main problems are high price and high cost. It is urgent to develop conductive silver paste products for coated glass with domestic technology. Summary of the invention

[0005] The purpose of the present invention is to provide a conductive silver paste for automotive coated glass and a preparation method thereof, which is used to solve the problems of low resistance, adhesion, wide sintering window, and bonding strength between the silver paste and copper foil.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A conductive silver paste for automotive coated glass, comprising the following components and contents by weight:

[0008]

[0009]

[0010] Furthermore, the flaky mixed silver powder is a mixture of large flaky silver powder and small flaky silver powder in a mass ratio of 1:(1-10);

[0011] The large-scale flaky silver powder has an average particle size of 8.0-10.0 μm, a tap density of 1.5-2.0 g / mL, and a bulk density of 0.5-1.0 g / mL;

[0012] The small-sized flaky silver powder has an average particle size of 4.0-5.0 μm, a tap density of 1.5-2.0 g / mL, and a loose density of 0.8-1.2 g / mL.

[0013] Furthermore, the spherical silver powder has an average particle size of 1.0-1.5 μm, a tap density of 2.0-2.5 g / mL, and a loose density of 1.0-1.5 g / mL.

[0014] Furthermore, the organic resin is one or a combination of acrylic resin, ethyl cellulose, nitrocellulose, ethyl hydroxyethyl cellulose or wood rosin.

[0015] Furthermore, the organic solvent is one or a combination of terpineol, turpentine, diethylene glycol butyl ether, diethylene glycol dibutyl ether, butyl carbitol acetate, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether.

[0016] Furthermore, the organic additive is one or a combination of dibutyl phthalate, tributyl citrate, dioctyl phthalate, and trioctyl citrate.

[0017] A method for preparing a conductive silver paste for automotive coated glass comprises the following steps:

[0018] 1) Preparation of organic carrier: mixing organic resin and organic solvent to obtain organic carrier;

[0019] 2) Preparation of conductive silver paste: Mix and disperse flaky mixed silver powder, spherical silver powder, organic additives and organic carrier to obtain conductive silver paste.

[0020] Furthermore, in step 1), the mixing process is carried out at 75-85° C., and after mixing, the mixture is filtered through a 300-400 mesh sieve.

[0021] Furthermore, in step 2), after dispersion, grinding is performed in a three-roll mill.

[0022] Furthermore, the conductive silver paste has a fineness of less than 12 μm and a viscosity of 20-30 Pa·s.

[0023] Chinese patent application CN111370158A discloses a fine-line silver paste for passenger car glass and a preparation method thereof, comprising the following components in parts by weight: 60-80 parts of metallic silver powder; 3-7 parts of glass powder; 1-8 parts of polymer resin; 1-3 parts of organic additives; and 10-25 parts of organic solvent. Compared with the prior art, the product prepared by the present invention solves the problems of printing fineness, conductive properties, compactness, etc. of the silver paste and improves its service life.

[0024] Chinese patent application CN111370158A discloses a fine-line silver paste for passenger car glass and its preparation method. The substrate used is a float glass, which is ordinary glass. It is made by floating method. The principle is that the glass liquid is continuously flowed from the tank kiln and floated on the metal liquid surface to shape the glass. The glass powder in the silver paste has a similar compatibility principle with the float glass. The glass powder can act as an adhesive to stick the inorganic silver powder to the glass substrate.

[0025] In contrast, the substrate used in the present invention is a coated glass, i.e., conductive film glass, which is a functional glass. It is made by vapor-depositing a metal film on the transparent glass surface, or spraying a metal oxide conductive film on the heated glass surface. Products made of coated glass actually interact with the metal film layer on the glass surface, not with the underlying glass substrate. In the present invention, if glass powder is used, it will cause cracking and failure due to the mismatch of thermal expansion coefficients between the glass powder and the metal film layer.

[0026] Compared with the prior art, the present invention has the following characteristics:

[0027] 1) The present invention solves the problem of resistance fluctuation of conductive silver paste on coated glass during high-temperature sintering (550-750°C) by designing a mix of large and small flaky silver powders; designs spherical silver powder with small particle size to solve the adhesion between the conductive silver paste and the coated glass and improve the bonding strength between the silver layer and the copper foil; and further reduces the ash remaining after sintering the conductive silver paste by adjusting the type of organic resin, such as acrylic resin, and improves the bonding strength between the silver layer and the copper foil. The screen printing process of the conductive silver paste is optimized by selecting organic additives;

[0028] 2) The substrate used in the present invention is a coated glass, which is used for the first time in automobiles, which is a domestic and international first. At the same time, the conductive silver paste used for automobile coated glass is also a first. The silver powder in the conductive silver paste for coated glass is mainly flaky silver powder, which is also the first time to be used in high-temperature sintering silver paste. Flaky silver powder is generally the main powder in low-temperature curing silver paste, and is used in small amounts or is not applicable in high-temperature silver paste. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments are implemented based on the above technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0030] Embodiment 1:

[0031] A conductive silver paste for automobile coated glass, the preparation method of which comprises the following steps:

[0032] 1) Prepare the materials according to the following components and weight percentages, with a total amount of 1kg:

[0033] The raw materials are composed of the following components and weight percentages: 55% of mixed silver flake powder, 550g; 10% of spherical silver powder, 100g; 7% of organic resin, 70g; 27% of organic solvent, 270g; 1% of organic additive, 10g;

[0034] Among them, in the flaky mixed silver powder, the mass ratio of large flaky silver powder to small flaky silver powder is 1:1; the average particle size of large flaky silver powder is 8.54μm, the tap density is 1.78g / mL, and the bulk density is 0.72g / mL; the average particle size of small flaky silver powder is 4.36μm, the tap density is 1.54g / mL, and the bulk density is 0.89g / mL;

[0035] The average particle size of the spherical silver powder is 1.1 μm, the tap density is 2.2 g / mL, and the bulk density is 1.4 g / mL;

[0036] The organic resin is composed of acrylic resin and ethyl cellulose in a mass ratio of 1:1;

[0037] The organic solvent is terpineol;

[0038] The organic additive is dibutyl phthalate;

[0039] 2) Preparation of organic carrier: Mix the organic resin and the organic solvent, heat to 80°C and keep the temperature constant. After the organic resin is completely dissolved, filter on a 400-mesh mesh to remove impurities and obtain an organic carrier;

[0040] 3) Preparation of conductive silver paste: After weighing the flaky mixed silver powder and the spherical silver powder, fully mix them with the organic carrier and the organic additive in a mixer, and then use a high-speed dispersant to disperse them at high speed to obtain a uniform conductive paste;

[0041] 4) Production of conductive silver paste: The conductive paste is ground in a three-roll mill, and the fineness of the silver paste is adjusted to 8 μm and the viscosity is 27 Pa·S by roller fine-tuning to obtain a conductive silver paste for automotive coated glass.

[0042] Embodiment 2:

[0043] A conductive silver paste for automotive coated glass, the preparation method of which is different from that of Example 1 only in that:

[0044] In step 1), flaky mixed silver powder 75%, 750g; spherical silver powder 5%, 50g; organic resin 4%, 40g; organic solvent 15%, 150g; organic additive 1%, 10g;

[0045] The mass ratio of large-scale silver flake powder to small-scale silver flake powder is 1:2; the average particle size of small-scale silver flake powder is 4.08 μm, the tap density is 1.83 g / mL, and the bulk density is 1.07 g / mL;

[0046] The organic resin is composed of acrylic resin and nitrocellulose in a mass ratio of 2:1;

[0047] The organic solvent is diethylene glycol butyl ether;

[0048] The organic additive is tributyl citrate;

[0049] The fineness of the obtained conductive silver paste for automobile coated glass is 10 μm and the viscosity is 28 Pa·S.

[0050] The rest is the same as in Example 1.

[0051] Embodiment 3:

[0052] A conductive silver paste for automotive coated glass, the preparation method of which is different from that of Example 1 only in that:

[0053] In step 1), 80% of mixed silver powder in flake form, 800 g; 8% of mixed silver powder in spherical form, 80 g; 2% of organic resin, 20 g; 9.5% of organic solvent, 95 g; and 0.5% of organic additive, 5 g;

[0054] The mass ratio of large-scale silver flake powder to small-scale silver flake powder is 1:9;

[0055] The organic resin is acrylic resin;

[0056] The organic solvent is tripropylene glycol monomethyl ether;

[0057] The organic additive is dioctyl phthalate;

[0058] The fineness of the obtained conductive silver paste for automobile coated glass is 11 μm and the viscosity is 26 Pa·S.

[0059] The rest is the same as in Example 1.

[0060] Application examples:

[0061] In this embodiment, the performance of the conductive silver paste prepared in embodiments 1 to 3 is tested. The test standards and test results are shown in Table 1.

[0062] Table 1

[0063]

[0064] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and 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 conductive silver paste for automotive coated glass, characterized in that: It includes the following components and contents by weight: Flake mixed silver powder 50-80%; Spherical silver powder 5-10%; Organic resin 2-10%; Organic solvent 8-45%; Organic additives 0.5-2%; The flaky mixed silver powder is a mixture of large flaky silver powder and small flaky silver powder in a mass ratio of 1:(1-10); The large-scale flaky silver powder has an average particle size of 8.0-10.0 μm, a tap density of 1.5-2.0 g / mL, and a bulk density of 0.5-1.0 g / mL; The small-sized flaky silver powder has an average particle size of 4.0-5.0 μm, a tap density of 1.5-2.0 g / mL, and a bulk density of 0.8-1.2 g / mL; The spherical silver powder has an average particle size of 1.0-1.5 μm, a tap density of 2.0-2.5 g / mL, and a bulk density of 1.0-1.5 g / mL; The organic resin is one or a combination of acrylic resin, ethyl cellulose, nitrocellulose, ethyl hydroxyethyl cellulose or wood rosin; The organic solvent is one or a combination of terpineol, turpentine, diethylene glycol butyl ether, diethylene glycol dibutyl ether, butyl carbitol acetate, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether; The organic additive is one or a combination of dibutyl phthalate, tributyl citrate, dioctyl phthalate and trioctyl citrate.

2. The method for preparing a conductive silver paste for automotive coated glass according to claim 1, characterized in that: The method comprises the following steps: 1) Preparation of organic carrier: Mixing organic resin with organic solvent to obtain organic carrier; 2) Preparation of conductive silver paste: Mix and disperse flaky mixed silver powder, spherical silver powder, organic additives and organic carriers to obtain conductive silver paste.

3. The method for preparing a conductive silver paste for automotive coated glass according to claim 2, characterized in that: In step 1), the mixing process is carried out at 75-85° C., and after mixing, the mixture is filtered through a 300-400 mesh sieve.

4. The method for preparing a conductive silver paste for automotive coated glass according to claim 2, characterized in that: In step 2), after dispersion, grinding is performed in a three-roll mill.

5. The method for preparing a conductive silver paste for automotive coated glass according to claim 4, characterized in that: The fineness of the conductive silver paste is below 12 μm and the viscosity is 20-30 Pa·s.

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