Method for testing viscosity of photovoltaic silver paste

Abstract

The invention provides a method for testing the viscosity of photovoltaic silver paste, and belongs to the technical field of viscosity detection.The method comprises the following steps that silver powder is dispersed in an organic phase, and paste is obtained; performing primary defoaming on the slurry to obtain primary defoaming slurry; carrying out three-roller rolling on the defoamed slurry to obtain rolled slurry; the rolled slurry is subjected to secondary defoaming, and secondary defoaming slurry is obtained; beating, compacting and defoaming the secondary defoaming slurry to obtain photovoltaic silver paste; and reading the viscosity of the photovoltaic silver paste under the set rotor rotating speed by adopting a viscometer under the rotor stirring condition. According to the invention, defoaming treatment is carried out firstly, then three-roller rolling is carried out for grinding, four different roller distances are set in the grinding process for grinding twice respectively, uniform grinding is ensured, defoaming is carried out again after grinding is finished, and after a sample is put into a sample tank, knocking is carried out to completely eliminate bubbles, so that the accuracy and the stability of viscosity testing are facilitated.

Description

Technical Field

[0001] This invention relates to the field of viscosity testing technology, and specifically to a method for testing the viscosity of photovoltaic silver paste. Background Technology

[0002] Photovoltaic silver paste is a basic material primarily made of silver powder. It is a viscous paste composed of a mechanical mixture of high-purity silver powder, glass oxide, and organic materials, with silver powder playing a decisive role, accounting for approximately 98%. Silver paste is generally classified into conductive silver paste, resistive silver paste, and electrofused silver paste, with over 90% used for conductivity; therefore, photovoltaic silver paste is also known as conductive silver paste. Photovoltaic silver paste is an essential consumable in the production of photovoltaic cells, accounting for a relatively high percentage of its cost. Its performance directly affects the photoelectric performance of photovoltaic cells, making its testing crucial. Viscosity testing of silver paste typically involves uniformly mixing silver powder with glass powder and an organic carrier, grinding the mixture, and then testing the viscosity using a viscometer.

[0003] Existing viscosity testing methods (such as rotational viscometers) face serious sedimentation interference in silver powder pastes with high solids content (>90wt%), and the resulting silver paste contains a lot of air bubbles and gaps, causing unstable and distorted test data. Summary of the Invention

[0004] In view of the technical problems existing in the background art, this application provides a method for testing the viscosity of photovoltaic silver paste, aiming to solve the technical problems of unstable and distorted test data in existing viscosity testing methods.

[0005] In a first aspect, embodiments of this application provide a method for testing the viscosity of photovoltaic silver paste, comprising the following steps: S1. Disperse silver powder in the organic phase to obtain a slurry; S2. Degas the slurry once to obtain a degassed slurry; S3. The deaerated slurry is subjected to three-roll rolling to obtain rolled slurry; S4. The roller-rolled slurry is degassed a second time to obtain a second-degassed slurry; S5. The secondary degassing slurry is tapped and vibrated to degas and obtain photovoltaic silver paste; S6. Use a viscometer to read the viscosity of the photovoltaic silver paste at the set rotor speed under rotor stirring conditions.

[0006] In some embodiments, the organic phase includes at least one of ethyl cellulose, dibutyl phthalate, terpineol, and tributyl phosphate.

[0007] In some embodiments, the mass ratio of silver powder to organic phase is (15~20):(160~200).

[0008] In some embodiments, a degassing machine is used for secondary degassing in step S4. The speed of the degassing machine is 300~500 r / min, and the degassing time is 2~3 min.

[0009] In some embodiments, the three-roll rolling setup in step S3 requires two passes of the three rolls with different gaps: 0.12mm / 0.06mm, 0.08mm / 0.04mm, 0.04mm / 0.02mm, and 0.02 / 0.01mm.

[0010] In some embodiments, the number of taps in step S5 is 50 to 200.

[0011] In some embodiments, the rotor stirring conditions in step S6 are as follows: the rotation speed is adjusted sequentially to 10 r / min for 1 min, 1 r / min for 1 min, 10 r / min for 2 min, 50 r / min for 1 min, 100 r / min for 1 min, and 200 r / min for 1 min, with a standby interval of 30 s between each rotation speed range.

[0012] In some embodiments, the viscosity count value is read from the viscosity data in the steady-state range at a rotation speed of 50 r / min.

[0013] In some embodiments, the secondary deaerated slurry is allowed to stand and cool to room temperature for 30 minutes before being tapped and vibrated to deaerate.

[0014] The advantages of this application, which differ from existing technical solutions, include: In the silver paste sample preparation process of this invention, degassing is performed first, followed by three-roll milling. During the milling process, four different roller gaps are set to mill twice to ensure uniform milling. After milling, degassing is performed again. After the sample is placed in the sample tank, it is also knocked to completely eliminate the air bubbles, which is beneficial to the accuracy and stability of viscosity testing.

[0015] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Detailed Implementation

[0016] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification and claims of this application are intended to cover non-exclusive inclusion.

[0018] Existing viscosity testing methods (such as rotational viscometers) face serious sedimentation interference in silver powder pastes with high solids content (>90wt%), and the resulting silver paste contains a lot of air bubbles and gaps, causing unstable and distorted test data.

[0019] To address the technical problems of unstable and distorted test data in existing viscosity testing methods, this application provides a method for testing the viscosity of photovoltaic silver paste. In the silver paste sample preparation process, degassing is performed first, followed by three-roll milling. During the milling process, four different roller gaps are set to mill twice to ensure uniform milling. After milling, degassing is performed again, and the sample is placed in the sample tank and then tapped to completely eliminate air bubbles. This method is beneficial to the accuracy and stability of viscosity testing.

[0020] In the first aspect, the embodiments of this application provide a method for testing the viscosity of photovoltaic silver paste. Step 1: Stir the organic phase evenly, weigh 15~20g of the organic phase according to the proportion, the organic phase includes at least one of ethyl cellulose, dibutyl phthalate, terpineol, and tributyl phosphate, and then add 160~200g of silver powder to the organic phase and stir evenly until there is no dry powder, and the sample presents a uniform paste. Step 2: Place the mixed slurry into a degassing machine for degassing. The degassing machine speed is 300~500 r / min, and the time is 2min~3min. Step 3: Remove the sample from the degassing machine and roll it evenly in a three-roll mill. The three-roll mill should be set up for two passes with different gaps: 0.12mm / 0.06mm, 0.08mm / 0.04mm, 0.04mm / 0.02mm, and 0.02 / 0.01mm. Step 4: After rolling, collect all the slurry into the sample container and place it in a degassing machine for degassing. The degassing machine speed is 300~500 r / min, and the time is 2min~3min. After degassing, let the sample stand and cool for 30min to room temperature (25℃). Step 5: Remove the sample from the sample container and place it in the sample cell. Tap the sample 200 times to compact and degas it. Slowly place the No. 14 rotor into the sample cell and rotate the rotor slightly to perform secondary degassing. Step 6: Support the upper part of the rotor connecting rod, rotate clockwise to install the rotor, adjust the rotor to the torque of 0, and after the viscometer is preheated for 2 minutes, adjust the speed in sequence: 10 r / min for 1 minute, 1 r / min for 1 minute, 10 r / min for 2 minutes, 50 r / min for 1 minute, 100 r / min for 1 minute, and 200 r / min for 1 minute. The standby interval between each speed range is 30 seconds. Select the viscosity data in the stable range of 50 r / min.

[0021] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0022] I. Preparation Method Example 1 A method for testing the viscosity of photovoltaic silver paste includes the following steps: a. Stir the organic phase evenly, weigh 18g of terpineol according to the ratio, then add 180g of silver powder to the terpineol and stir evenly until there is no dry powder and the sample is in a uniform slurry. b. Place the mixed slurry into a degassing machine for degassing. The degassing machine speed is 500 r / min and the time is 2min. c. Take the sample out of the degassing machine and roll it evenly in a three-roll mill. The three-roll mill is set up to roll twice with different gaps: 0.12mm / 0.06mm, 0.08mm / 0.04mm, 0.04mm / 0.02mm, and 0.02 / 0.01mm. d. After rolling, collect all the slurry into the sample container and place it in a degassing machine at 500 r / min for 2 min. After degassing, allow the sample to cool to room temperature (25℃) for 30 min. e. Take the sample out of the sample container and place it in the sample tank. Tap it 200 times to compact and degas the sample. Slowly place the No. 14 rotor into the sample tank and rotate the rotor slightly to perform secondary degassing. f. Support the upper part of the rotor connecting rod, rotate clockwise to install the rotor, adjust the rotor to the torque of 0, and after the viscometer is preheated for 2 minutes, adjust the speed in sequence: 10 r / min for 1 min, 1 r / min for 1 min, 10 r / min for 2 min, 50 r / min for 1 min, 100 r / min for 1 min, 200 r / min for 1 min, with a standby interval of 30 seconds between each speed range, and select the viscosity data in the stable range of 50 r / min.

[0023] Example 2 A method for testing the viscosity of photovoltaic silver paste includes the following steps: a. Stir the organic phase evenly, weigh 18g of ethyl cellulose according to the ratio, then add 180g of silver powder to the ethyl cellulose and stir evenly until there is no dry powder and the sample is in a uniform slurry. b. Place the mixed slurry into a degassing machine for degassing. The degassing machine speed is 400 r / min and the time is 2min. c. Remove the sample from the degassing machine and roll it evenly in a three-roll mill. The three-roll mill should be set up for two passes with different gaps: 0.12mm / 0.06mm, 0.08mm / 0.04mm, 0.04mm / 0.02mm, and 0.02 / 0.01mm. d. After rolling, collect all the slurry into a sample container and place it in a degassing machine at 400 r / min for 2 min. After degassing, allow the sample to cool to room temperature (25℃) for 30 min. e. Take the sample out of the sample container and place it in the sample tank. Tap it 100 times to compact and degas the sample. Slowly place the No. 14 rotor into the sample tank and rotate the rotor slightly to perform secondary degassing. f. Support the upper part of the rotor connecting rod, rotate clockwise to install the rotor, and adjust the speed in sequence: 10 r / min for 1 min, 1 r / min for 1 min, 10 r / min for 2 min, 50 r / min for 1 min, 100 r / min for 1 min, 200 r / min for 1 min. The standby interval for each speed range is 30 seconds. Select the viscosity data in the stable range of 50 r / min.

[0024] Example 3 A method for testing the viscosity of photovoltaic silver paste includes the following steps: a. Stir the organic phase evenly, weigh 18g of tributyl phosphate according to the ratio, then add 180g of silver powder to the tributyl phosphate and stir evenly until there is no dry powder and the sample is in a uniform slurry. b. Place the mixed slurry into a degassing machine for degassing. The degassing machine speed is 300 r / min and the time is 2min. c. Remove the sample from the degassing machine and roll it evenly in a three-roll mill. The three-roll mill should be set up for two passes with different gaps: 0.12mm / 0.06mm, 0.08mm / 0.04mm, 0.04mm / 0.02mm, and 0.02 / 0.01mm. d. After rolling, collect all the slurry into the sample container and place it in a degassing machine at 300 r / min for 2 min. After degassing, let the sample stand and cool for 30 min to room temperature (25℃). e. Take the sample out of the sample container and place it in the sample tank. Tap it 50 times to compact and degas the sample. Slowly place the No. 14 rotor into the sample tank and rotate the rotor slightly to perform secondary degassing. f. Support the upper part of the rotor connecting rod, rotate clockwise to install the rotor, adjust the rotor to the torque of 0, and after the viscometer is preheated for 2 minutes, adjust the speed in sequence: 10 r / min for 1 min, 1 r / min for 1 min, 10 r / min for 2 min, 50 r / min for 1 min, 100 r / min for 1 min, 200 r / min for 1 min, with a standby interval of 30 seconds between each speed range, and select the viscosity data in the stable range of 50 r / min.

[0025] Comparative Example 1 A method for testing the viscosity of photovoltaic silver paste includes the following steps: a. Stir the organic phase evenly, weigh 18g of terpineol according to the ratio, then add 180g of silver powder to the terpineol and stir evenly until there is no dry powder and the sample is in a uniform slurry. b. Place the mixed slurry into a degassing machine for degassing. The degassing machine speed is 300 r / min and the time is 2min. c. Remove the sample from the degassing machine and roll it evenly in a three-roll mill. The three-roll mill should be set up for two passes with different gaps: 0.12mm / 0.06mm, 0.08mm / 0.04mm, 0.04mm / 0.02mm, and 0.02 / 0.01mm. d. After rolling, collect all the slurry into the sample container and place it in a degassing machine at 300 r / min for 2 min. After degassing, let the sample stand and cool for 30 min to room temperature (25℃). e. Remove the sample from the sample container and place it in the sample tank. Slowly place rotor No. 14 into the sample tank and rotate the rotor slightly to perform secondary degassing. f. Support the upper part of the rotor connecting rod, rotate clockwise to install the rotor, adjust the rotor to the torque of 0, and after the viscometer is preheated for 2 minutes, adjust the speed in sequence: 10 r / min for 1 min, 1 r / min for 1 min, 10 r / min for 2 min, 50 r / min for 1 min, 100 r / min for 1 min, 200 r / min for 1 min, with a standby interval of 30 seconds between each speed range, and select the viscosity data in the 50 rpm stable range.

[0026] Comparative Example 2 A method for testing the viscosity of photovoltaic silver paste includes the following steps: a. Stir the organic phase evenly, weigh 18g of terpineol according to the ratio, then add 180g of silver powder to the terpineol and stir evenly until there is no dry powder and the sample is in a uniform slurry. b. Place the mixed slurry into a degassing machine for degassing. The degassing machine speed is 300 r / min and the time is 2min. c. Remove the sample from the degassing machine and roll it evenly in a three-roll mill. The three-roll mill should be set up for 8 passes with a fixed inlet and outlet roll gap of 0.12mm / 0.06mm. d. After rolling, collect all the slurry into the sample container and place it in a degassing machine at 300 r / min for 2 min. After degassing, let the sample stand and cool for 30 min to room temperature (25℃). e. Take the sample out of the sample container and place it in the sample tank. Tap it 200 times to compact and degas the sample. Slowly place the No. 14 rotor into the sample tank and rotate the rotor slightly to perform secondary degassing. f. Support the upper part of the rotor connecting rod, rotate clockwise to install the rotor, adjust the rotor to the torque of 0, and after the viscometer is preheated for 2 minutes, adjust the speed in sequence: 10 r / min for 1 min, 1 r / min for 1 min, 10 r / min for 2 min, 50 r / min for 1 min, 100 r / min for 1 min, 200 r / min for 1 min, with a standby interval of 30 seconds between each speed range, and select the viscosity data in the 50 rpm stable range.

[0027] II. Analysis of Test Results for Each Embodiment and Comparative Example The viscosity test results of the above embodiments and comparative examples are shown in Table 1 below: Table 1. Viscosity test results for each embodiment and comparative example.

[0028] As shown in Table 1, Examples 1, 2, and 3 all underwent grinding with different roller gaps and subsequent secondary degassing by beating after grinding. Comparative Example 1, however, did not undergo secondary degassing by beating before testing, resulting in a larger standard deviation, indicating that secondary degassing by beating before testing has a greater impact. Comparative Example 2, which did not undergo grinding with different roller gaps, also had a large standard deviation, suggesting that grinding with different roller gaps resulted in better uniformity of the slurry. In conclusion, setting different roller gaps for grinding and performing secondary degassing both contribute to the accuracy and stability of viscosity testing.

[0029] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for testing the viscosity of photovoltaic silver paste, characterized in that, Includes the following steps: S1. Disperse silver powder in the organic phase to obtain a slurry; S2. Degas the slurry once to obtain a degassed slurry; S3. The deaerated slurry is subjected to three-roll rolling to obtain rolled slurry; S4. The roller-rolled slurry is degassed a second time to obtain a second-degassed slurry; S5. The secondary degassing slurry is tapped and vibrated to degas and obtain photovoltaic silver paste; S6. Use a viscometer to read the viscosity of the photovoltaic silver paste at a set rotor speed under rotor stirring conditions.

2. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, The organic phase includes at least one of ethyl cellulose, dibutyl phthalate, terpineol, and tributyl phosphate.

3. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, The mass ratio of silver powder to organic phase is (15~20):(160~200).

4. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, In step S2, a degassing machine is used for one degassing operation. The speed of the degassing machine is 300~500 r / min, and the degassing time is 2~3 min.

5. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, In step S4, a degassing machine is used for secondary degassing. The degassing machine rotates at 300-500 r / min and the degassing time is 2-3 min.

6. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, In step S3, the three-roll rolling setup requires two passes with each roll having a gap of 0.12mm / 0.06mm, 0.08mm / 0.04mm, 0.04mm / 0.02mm, and 0.02 / 0.01mm.

7. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, In step S5, the number of taps is 50 to 200.

8. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, In step S6, the rotor stirring conditions are as follows: the rotation speed is adjusted sequentially to 10 r / min for 1 min, 1 r / min for 1 min, 10 r / min for 2 min, 50 r / min for 1 min, 100 r / min for 1 min, and 200 r / min for 1 min, with a standby interval of 30 s between each rotation speed range.

9. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, Viscosity count values ​​are read from the viscosity data in the steady-state range at a rotation speed of 50 r / min.

10. The method for testing the viscosity of photovoltaic silver paste according to claim 1, characterized in that, After the secondary degassing, the slurry is allowed to stand and cool to room temperature for 30 minutes before being tapped and vibrated to degas again.

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