A noble metal colorimetric detection method and system

Abstract

The application provides a noble metal colorimetric detection method and system. The noble metal colorimetric detection method comprises the following steps: preparing reference noble metal paste formed by mixing noble metal powder standard and organic carrier, preparing to-be-detected noble metal paste formed by mixing to-be-detected noble metal powder and organic carrier, homogenizing and rolling the reference slurry sample and the to-be-detected slurry sample; placing the reference slurry sample and the to-be-detected slurry sample on a substrate respectively, flattening by using a cover sheet, testing by using a colorimeter, obtaining detection difference values AL, Da and Db of the to-be-detected slurry sample and the reference slurry sample, calculating a color difference value DE, and determining the stability of noble metal slurry application.

Description

Technical Field

[0001] This invention relates to the field of colorimetric detection technology, specifically to a method and system for colorimetric detection of precious metals. Background Technology

[0002] Precious metals mainly refer to eight metallic elements: gold, silver, and the platinum group metals (ruthenium, rhodium, palladium, osmium, iridium, and platinum). Precious metal powders are widely used conductive materials in modern industry. In fields such as photovoltaic manufacturing and electronic packaging, the use of precious metal powders as the main conductive paste plays a crucial role in the performance of end products. In the application fields of precious metal powders, their performance is primarily achieved by preparing them into pastes.

[0003] In the process of preparing conductive pastes from precious metal powders, they are generally mixed with organic materials and a small amount of other additives. The types and amounts of organic materials and additives vary depending on the application and the manufacturer. After uniform mixing, the conductive paste is formed. Currently, the main product indicators in the precious metal powder industry include morphology, particle size distribution, specific surface area, tap density, and impurity element content. Manufacturers assess the batch-to-batch stability of precious metal powders by analyzing these characteristic indicators. However, from an application perspective, the introduction of surface treatment technology introduces uncertainty into the stability assessment of precious metal powders. The changes in characteristic indicators of precious metal powders caused by surface treatment are extremely minor and cannot be assessed using existing methods. Furthermore, evaluating the stability of surface treatment based on end-application performance requires cooperation from downstream applications, resulting in extremely low testing efficiency.

[0004] In the field of colorimetric testing of precious metal powders, existing technologies employ methods that directly test the colorimetric properties of precious metal powder products. However, this method cannot fully reflect the colorimetric differences of precious metal powders during application. Furthermore, factors such as the accumulation, agglomeration, and packaging differences of precious metal powders all affect the colorimetric test results, leading to poor test accuracy. Summary of the Invention

[0005] Therefore, it is necessary to provide a method and system for detecting the color of precious metals.

[0006] The present invention adopts the following technical solution:

[0007] This invention provides a method for detecting the colorimetry of precious metals, comprising the following steps: preparing a reference precious metal paste formed by mixing a precious metal powder standard and an organic carrier; preparing a test precious metal paste formed by mixing a precious metal powder to be tested and an organic carrier; homogenizing and rolling the reference precious metal paste and the test precious metal paste to obtain a reference slurry sample and a test slurry sample; placing the reference slurry sample and the test slurry sample on a substrate, pressing them flat with a cover plate, and testing them with a colorimeter; calculating the detection differences ΔL, Δa, and Δb between the test slurry sample and the reference slurry sample; and calculating the color difference value ΔE.

[0008] ΔE=[(ΔL) 2 + (Δa) 2 + (Δb) 2 ] 1 / 2 ;

[0009] If ΔE < 1, the color of the precious metal slurry to be tested is deemed to be qualified.

[0010] If ΔE≥1, the color of the precious metal slurry being tested is deemed unqualified.

[0011] In some embodiments, both the substrate and the cover glass are made of AR glass with a light transmittance of ≥95%.

[0012] In some embodiments, the method of flattening using a cover plate is as follows: both the substrate and the cover plate are designed with bolt holes, and the bolts are tightened using a torque wrench.

[0013] In some embodiments, the substrate has the following dimensions: length 1~10mm, width 1~10mm, thickness 0.5~5mm, and torque wrench torque value 0.1~3N.

[0014] In some embodiments, a three-roll mill is used to roll the precious metal paste.

[0015] In some embodiments, the precious metal is selected from one or more of gold powder, silver powder, and platinum powder, and the organic carrier includes an organic solvent and an additive. The organic solvent is selected from one or more of ethylene glycol diglycidyl ether, diethylene glycol butyl ether acetate, methyl isobutyl ketone, and dimethyl oxalate, and the additive is selected from one or more of acrylic resin, ethyl cellulose, and epoxy resin.

[0016] Preferably, the mass ratio of precious metal powder to organic carrier is (6~8):(0.7~4).

[0017] The present invention also provides a precious metal colorimetric detection system, which is used in conjunction with the above-mentioned precious metal colorimetric detection method, including a colorimeter and a precious metal slurry pressing module; the precious metal slurry pressing module includes a substrate, a cover plate, fastening bolts and a torque wrench, the substrate and the cover plate are provided with matching threaded holes, and the pressing and fixing are achieved by the cooperation of the fastening bolts and the torque wrench.

[0018] Compared with the prior art, the core technical advantages and beneficial effects of this invention are as follows:

[0019] The colorimetric detection method for precious metals of this invention evaluates the surface treatment stability of precious metal powders. It is efficient and low-cost, and facilitates preliminary analysis of the application performance of precious metal powders before application, ensuring or even improving the stability of precious metals in product applications. Attached Figure Description

[0020] Figure 1 This is a statistical graph showing the color difference value ΔE of precious metal slurry and its slurry-forming properties. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The following embodiments are only used to illustrate the present invention, and are not intended to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0022] Precious Metal Colorimetric Detection System:

[0023] This system is designed for use with precious metal colorimetry testing methods and includes a colorimeter and a precious metal paste pressing module. The precious metal paste pressing module includes a substrate, a cover plate, fastening bolts, and a torque wrench. The substrate and cover plate have matching threaded holes, and the pressing and fixing are achieved by the cooperation of the fastening bolts and the torque wrench (preferably with a torque value of 0.1~3N).

[0024] The dimensions of the substrate are: length 1~10mm, width 1~10mm, and thickness 0.5~5mm.

[0025] Both the substrate and the cover glass are selected from AR glass with a light transmittance of ≥95%. No scratches should be generated during the addition and flattening of the slurry to avoid interfering with the results.

[0026] Example 1

[0027] This embodiment provides a method for detecting the colorimetric properties of silver, using the aforementioned precious metal colorimetric detection system, and includes the following steps:

[0028] S1, prepare standard samples and test samples.

[0029] A reference precious metal paste was prepared by mixing 8g of silver powder standard (purchased from Smet, 2-3μm, purity 99.5%) and 2g of organic carrier in a slurry container and stirring manually until homogeneous. The organic carrier consisted of ethylene glycol diglycidyl ether (mass ratio 1:2) as an organic solvent and polymethyl methacrylate (purchased from Maclean's, molecular weight Mw 100,000~120,000) as an auxiliary agent.

[0030] A paste-like substance of precious metal to be tested was prepared by mixing 8g of silver powder to be tested (2-3 μm silver powder was prepared according to the method of Example 1 in patent document CN114871444A, washed until the conductivity was 20uS / cm and the purity was 99.5%) and 2g of organic carrier.

[0031] The reference precious metal paste and the test precious metal paste were placed in a homogenizer and homogenized at 1200 rpm for 6 min. The paste was then rolled using a three-roll mill to obtain the reference paste sample and the test paste sample.

[0032] S2, colorimetric testing, result calculation and judgment.

[0033] Place 1g of reference slurry sample (hereinafter referred to as "standard sample") and 1g of test slurry sample (hereinafter referred to as "test sample") on the substrate, cover the slurry with a cover plate, flatten it, and tighten the bolt with a torque wrench at the set torque of 0.7N.

[0034] Use a colorimeter to perform the test and record the sample detection values: L, a, b, and ΔL, Δa, Δb.

[0035] The statistical results are shown in the table below:

[0036] Example 1: Statistical Table of Colorimetric Test Results

[0037]

[0038] The color difference value ΔE is calculated using the following formula:

[0039] ΔE=[(ΔL) 2 + (Δa) 2 + (Δb) 2 ] 1 / 2 ;

[0040] The calculated value of ΔE is 0.18, indicating that the color of the precious metal slurry being tested is qualified.

[0041] In this embodiment, the slurry sample is pressed with a cover plate and subjected to increased torque, which avoids the influence of air bubbles during the slurry loading process on the test results. Furthermore, the amount used is very small, and the loss is very low. The effect of the additional surface treatment agent added to the silver powder on the performance indicators can be preliminarily determined using a spectrophotometer, which is extremely efficient.

[0042] Example 2

[0043] This embodiment provides a method for detecting the colorimetric properties of silver, using the aforementioned precious metal colorimetric detection system, and includes the following steps:

[0044] S1, prepare standard samples and test samples.

[0045] A reference precious metal paste was prepared by mixing 8g of silver powder standard (purchased from Simite, 2-3μm, purity 99.5%) and 2g of organic carrier in a slurry container and stirring manually until homogeneous. The organic carrier consisted of ethylene glycol diglycidyl ether (organic solvent) and polymethyl methacrylate (auxiliary agent) in a mass ratio of 1:2.

[0046] A paste-like substance of the precious metal to be tested was prepared by mixing 8g of the precious metal powder to be tested (2-3 μm silver powder prepared according to the method of Example 1 in patent CN114871444A, washed until the conductivity is 50-60 uS / cm and the purity is 99.4%) and 2g of organic carrier.

[0047] The reference precious metal paste and the test precious metal paste were placed in a homogenizer and homogenized at 1200 rpm for 6 minutes. The paste was then rolled using a three-roll mill to obtain the reference paste sample and the test paste sample.

[0048] S2, colorimetric testing, result calculation and judgment.

[0049] Place 1 g of reference slurry sample (hereinafter referred to as "standard sample") and 1 g of slurry sample to be tested (hereinafter referred to as "test sample") on the substrate, cover the slurry with a cover plate, flatten it, and tighten the bolt with a torque wrench at the set torque of 1.5 N.

[0050] The colorimeter was used to perform the tests, and the sample detection values ​​were recorded: L, a, b, and ΔL, Δa, Δb. The results are shown in the table below:

[0051] Example 2: Statistical Table of Colorimetric Test Results

[0052]

[0053] The color difference value ΔE is calculated using the following formula:

[0054] ΔE=[(ΔL) 2+ (Δa) 2 + (Δb) 2 ] 1 / 2 ;

[0055] The calculated value of ΔE is 0.21, indicating that the color of the precious metal slurry being tested is qualified.

[0056] In this embodiment, the slurry sample is pressed with a cover plate, and the torque conditions are within a certain range. This can effectively avoid the influence of air bubbles on the test results during the slurry loading process, and the amount used is very small, resulting in very low loss.

[0057] Comparative Example 1

[0058] This comparative example provides a method for detecting the colorimetry of silver paste, using the same proportions and colorimetry detection system as the precious metal paste in Example 1, and includes the following steps:

[0059] S1, prepare standard samples and test samples.

[0060] A reference precious metal paste was prepared by placing 40 g of silver powder standard (purchased from Simite, 2-3 μm, purity 99.5%) and 10 g of organic carrier in a slurry container and manually stirring until homogeneous. The organic carrier consisted of ethylene glycol diglycidyl ether (an organic solvent) and polymethyl methacrylate (a methyl methacrylate additive) in a mass ratio of 1:2.

[0061] A paste-like substance of precious metal to be tested was prepared by mixing 40g of silver powder to be tested (2-3μm silver powder was prepared according to the method of Example 1 of patent CN114871444A, washed until the conductivity was less than 10uS / cm and the purity was 99.9%) and 10g of organic carrier.

[0062] The reference precious metal paste and the test precious metal paste were placed in a homogenizer and homogenized at 1200 rpm for 6 minutes. The paste was then rolled using a three-roll mill to obtain the reference paste sample and the test paste sample.

[0063] S2, colorimetric testing, result calculation and judgment.

[0064] The reference slurry sample (hereinafter referred to as "standard sample") and the slurry sample to be tested (hereinafter referred to as "test sample") are respectively placed into cuvettes and tested using a colorimeter.

[0065] Record the sample detection values: L, a, b, and ΔL, Δa, Δb. The statistical results are shown in the table below:

[0066] Comparative Example 1: Statistical Table of Colorimetric Test Results

[0067]

[0068] The color difference value ΔE is calculated using the following formula:

[0069] ΔE=[(ΔL) 2 + (Δa) 2 + (Δb) 2 ] 1 / 2 ;

[0070] The calculated value of ΔE is 2.24, indicating that the color of the precious metal slurry being tested is unqualified.

[0071] The silver powder prepared in this comparative example has higher purity, but due to the lack of surface coating agent, its color is whiter, and the test results deviate from the standard sample. During slurry testing, the deviation in results caused agglomeration of the silver powder when mixed with the slurry, resulting in a larger powder fineness. Furthermore, conventional spectrophotometers require a large number of cuvettes, leading to a waste of precious metals. Air bubbles introduced during sample loading also affect the whiter test results. Additionally, the inability to seal the sample causes the slurry to flow, requiring rapid testing to obtain results.

[0072] It should be noted that normal silver powder is coated with a small amount of dispersant. The higher purity of the silver powder in this comparative example indicates that there is less organic matter coated on the surface of the silver powder, which leads to the color change. In the final slurry test, the lack of coating on the surface of the silver powder caused incompatibility between the silver powder and the slurry, resulting in agglomeration and changes in the fineness of the slurry.

[0073] The statistical results of the slurry fineness (referring to the agglomeration caused by the silver powder not being well dispersed in the organic carrier when mixed with the slurry, which is the result obtained by scraper testing) of the above test examples are shown in the table below:

[0074] Statistical Table of Fineness Differences in Silver Powder Paste in Experimental Examples

[0075]

[0076] Based on the above experimental examples, it can be concluded that: the color difference between the tested precious metal slurries in Examples 1 and 2 and the standard samples is less than 1, and the difference in fineness between Examples 1 and 2 and the standard samples is less than 1 μm.

[0077] Example 3

[0078] This embodiment provides a method for detecting the color intensity of gold, using the aforementioned precious metal color intensity detection system, and includes the following steps:

[0079] S1, prepare standard samples and test samples.

[0080] A reference precious metal paste was prepared by mixing 0.7 g of gold powder standard (purchased from Tanaka, Japan, purity 99.8%) and 0.3 g of organic carrier in a slurry container and manually stirring until homogeneous. The organic carrier consisted of dimethyl oxalate as an organic solvent and ethyl cellulose as an auxiliary agent in a 1:1 mass ratio.

[0081] A paste-like substance of the precious metal to be tested was prepared by mixing 0.7 g of the precious metal powder to be tested (gold powder prepared according to the method of Example 1 of Patent CN118682140B, with a purity of 99.8%) and 0.3 g of organic carrier.

[0082] The reference precious metal paste and the test precious metal paste were placed in a homogenizer and homogenized at 1200 rpm for 6 minutes. The paste was then rolled using a three-roll mill to obtain the reference paste sample and the test paste sample.

[0083] S2, colorimetric testing, result calculation and judgment.

[0084] Place 0.5g of reference slurry sample (hereinafter referred to as "standard sample") and 0.5g of slurry sample to be tested (hereinafter referred to as "test sample") on the substrate, cover the slurry with a cover plate, flatten it, and tighten the bolt with a torque wrench at the set torque of 2N.

[0085] The colorimeter was used to perform the tests, and the sample detection values ​​were recorded: L, a, b, and ΔL, Δa, Δb. The results are shown in the table below:

[0086] Example 3: Statistical Table of Colorimetric Test Results

[0087]

[0088] The color difference value ΔE is calculated using the following formula:

[0089] ΔE=[(ΔL) 2 + (Δa) 2 + (Δb) 2 ] 1 / 2 ;

[0090] The calculated value of ΔE is 0.12, indicating that the color of the precious metal slurry being tested is qualified.

[0091] Statistical Table of Fineness Differences in Gold Powder Slurry in Experimental Examples

[0092]

[0093] In this embodiment, the fineness difference of the test slurry is within 1 μm, and the color difference is also within 1.

[0094] Beyond the examples mentioned above, the inventors' team conducted numerous experiments and discovered the following:

[0095] 1. Through extensive laboratory research, this invention has found that when the precious metal is selected from one or more of gold powder, silver powder, and platinum powder, the organic solvent is selected from one or more of ethylene glycol diglycidyl ether, diethylene glycol butyl ether acetate, methyl isobutyl ketone, and dimethyl oxalate, and the auxiliary agent is selected from one or more of acrylic resin, ethyl cellulose, and epoxy resin, and the preferred mass ratio of precious metal powder to organic carrier is (6~8):(0.7~4), it can effectively test the fineness difference of precious metal slurry and the application color. Based on actual application, it can be concluded that: if ΔE < 1, the application color of the precious metal slurry is qualified; if ΔE ≥ 1, the application color of the precious metal slurry is unqualified.

[0096] 2. In the precious metal colorimetric detection system of this invention, both the substrate and the cover plate are made of AR glass with a light transmittance ≥95%. Bolt holes are designed on both the substrate and the cover plate. A torque wrench is used to tighten the bolts, with a torque value of 0.1~3N. The cover plate is used to flatten the metal. The organic solvent and additives are preferably acrylic or epoxy systems commonly used by downstream slurry customers. The solvent is generally a highly soluble organic solvent. This method can effectively determine whether the colorimetric properties of the precious metal slurry being tested are qualified. See the acceptable range for details. Figure 1 As shown, it is possible to effectively evaluate the surface treatment stability of precious metal powders.

[0097] 3. Under the premise of simulating the actual application scenario of precious metal powder, the color of the precious metal powder slurry is tested, which can be used for the performance evaluation and quality control of precious metal powder. By ensuring the uniformity of the test samples and the authenticity of the indicators, the influence of external materials and human factors on the test results is avoided. The test results have good repeatability and representativeness, and have promotion and application value in industrial development.

[0098] It should be noted that the above embodiments are only for further elaboration and explanation of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention. The method of the present invention is only a preferred embodiment and is not intended to limit the scope of protection of the present invention. 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. A method for detecting the colorimetry of precious metals, characterized in that, Includes the following steps: A reference precious metal paste was prepared by mixing a precious metal powder standard with an organic carrier, and a test precious metal paste was prepared by mixing a precious metal powder to be tested with an organic carrier. The reference precious metal paste and the test precious metal paste were homogenized and rolled to obtain the reference slurry sample and the test slurry sample, respectively. The reference slurry sample and the slurry sample to be tested were placed on the substrate and flattened using a cover plate. A colorimeter was used for testing, and the color difference values ​​ΔL, Δa, and Δb between the slurry sample to be tested and the reference slurry sample were calculated. The color difference value ΔE was also calculated. ΔE=[(ΔL) 2 + (Δa) 2 + (Δb) 2 ] 1 / 2 ; If ΔE < 1, the color of the precious metal slurry to be tested is deemed to be qualified. If △E≥1, the color of the precious metal being tested in the slurry is deemed unqualified.

2. The method for detecting the colorimetry of precious metals according to claim 1, characterized in that, Both the substrate and the cover glass are made of AR glass with a light transmittance of ≥95%.

3. The method for detecting the colorimetry of precious metals according to claim 2, characterized in that, The method of flattening using the cover plate is as follows: both the substrate and the cover plate are designed with bolt holes, and the bolts are tightened using a torque wrench.

4. The method for detecting the colorimetry of precious metals according to claim 3, characterized in that, The substrate has the following dimensions: length 1~10mm, width 1~10mm, thickness 0.5~5mm, and torque wrench torque value 0.1~3N.

5. The method for detecting the colorimetry of precious metals according to any one of claims 1 to 4, characterized in that, A three-roll mill is used to roll the precious metal paste.

6. The method for detecting the colorimetry of precious metals according to claim 1, characterized in that, The precious metal is selected from one or more of gold powder, silver powder, and platinum powder; the organic carrier includes an organic solvent and an additive; the organic solvent is selected from one or more of ethylene glycol diglycidyl ether, diethylene glycol butyl ether acetate, and methyl isobutyl ketone; the additive is selected from one or more of acrylic resin, ethyl cellulose, and epoxy resin.

7. The method for detecting the colorimetry of precious metals according to claim 6, characterized in that, The ratio of precious metal powder to organic carrier is (6~10):(0.7~4).

8. A precious metal colorimetric detection system, used in conjunction with the precious metal colorimetric detection method according to any one of claims 1 to 7, characterized in that, Includes a colorimeter and a precious metal slurry pressing module; The precious metal slurry pressing module includes a substrate, a cover plate, fastening bolts, and a torque wrench. The substrate and the cover plate are provided with matching threaded holes, and the pressing and fixing are achieved by the cooperation of the fastening bolts and the torque wrench.

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