Method for detecting temperature resistance of filler for silicone sealant

Abstract

The application discloses a kind of detection methods of the temperature resistance of filler for organic silicon sealant, belong to material detection technical field;Including determining the initial fineness value of filler sample, record as L0;Filler sample is baked at 150~180 ℃ condition 2~4 hours;Determine the fineness value of filler sample after baking, record as L1;If L1-L0≥5 μm, determine this filler sample after high temperature will have the phenomenon of return coarse, poor temperature resistance;If L1-L0<5 μm, then determine this filler sample temperature resistance is good;The method described in the application is simple, fast detection, low equipment requirement and accurate and reliable result;Solve the existing problems, such as operation complex, detection efficiency low and poor correlation with actual application of temperature resistance detection method of filler for organic silicon sealant.

Description

Technical Field

[0001] This invention belongs to the field of materials testing technology, specifically a method for testing the temperature resistance of fillers used in silicone sealants; it is used to evaluate the stability of fillers in high-temperature environments, and is particularly suitable for rapid screening and quality control of the temperature resistance performance of fillers in the production process of silicone sealants. Background Technology

[0002] Silicone sealants, as high-performance sealing materials, are widely used in construction, automotive, electronics, and other fields. Their basic components mainly include silicone polymers, fillers, catalysts, solvents, and other additives. Among these, fillers play a crucial role, not only improving the sealant's strength and durability but also enhancing its heat resistance. Common fillers include calcium carbonate, talc, kaolin, wollastonite, and barium sulfate, and the temperature resistance of these fillers directly affects the overall temperature resistance of the silicone sealant.

[0003] Currently, silicone sealants require high temperature resistance, and their temperature range varies depending on the application. Generally, silicone sealants have a temperature range of -45℃ to 350℃, maintaining stable physicochemical properties under extreme temperature conditions. Some special-purpose silicone sealants, such as high-temperature resistant silicone sealants, can withstand temperatures from -50℃ to 250℃, while some high-performance products can even withstand temperatures from -60℃ to 260℃. Therefore, the temperature resistance of fillers has a significant impact on the overall performance of silicone sealants.

[0004] Existing methods for testing the temperature resistance of packing materials mainly include thermogravimetric analysis, differential scanning calorimetry, high-temperature mechanical property testing, thermal cycling testing, and thermal shock testing. While these methods can provide relatively comprehensive data on the thermal properties of packing materials, they have the following limitations: 1. High equipment requirements: Instrumental analysis methods such as thermogravimetric analysis and differential scanning calorimetry require expensive professional equipment and are complex to operate. They require professional technicians to operate and analyze the data, which increases the testing cost and technical threshold.

[0005] 2. Long testing cycle: Methods such as high-temperature mechanical property testing, thermal cycling testing, and thermal shock testing require a long testing cycle, usually taking several hours or even days to complete, which cannot meet the needs of rapid screening.

[0006] 3. Complex sample preparation: Existing detection methods usually require complex sample preparation processes, such as preparation of samples with specific shapes and surface treatment, which increases the complexity and workload of detection.

[0007] 4. Poor correlation with practical applications: Although some testing methods can provide thermal performance data of fillers, these data are not strongly correlated with the actual performance of fillers in silicone sealants, making it difficult to accurately predict the performance of fillers in practical applications.

[0008] 5. Although the fineness test is a simple and intuitive method for evaluating the high-temperature stability of fillers, it can only provide limited performance information and cannot comprehensively evaluate the physical and chemical changes of fillers at high temperatures. Moreover, the test results are greatly affected by the properties of the matrix material and the test conditions. Summary of the Invention

[0009] This invention overcomes the shortcomings of existing technologies and proposes a method for testing the temperature resistance of fillers used in silicone sealants. It solves the problems of complex operation, low testing efficiency, high equipment requirements, and poor correlation with practical applications inherent in existing methods for testing the temperature resistance of fillers used in silicone sealants. This invention is achieved through the following technical solution: A method for testing the temperature resistance of fillers used in silicone sealants includes the following steps: S1. Measure the initial fineness value of the filler sample and record it as L0; S2. Bake the filler sample at 150~180℃ for 2~4 hours; S3. Measure the fineness value of the filler sample after baking and record it as L1; If L1-L0≥5μm, the filler sample is judged to have coarsening after high temperature and has poor temperature resistance; if L1-L0<5μm, the filler sample is judged to have good temperature resistance.

[0010] Preferably, the filler sample is a mixture of filler and hydroxyl-terminated polydimethylsiloxane.

[0011] Preferably, the hydroxyl-terminated polydimethylsiloxane has a viscosity of 2000-1000000 mm at 25°C. 2 / s.

[0012] Preferably, the hydroxyl-terminated polydimethylsiloxane has a viscosity of 10,000–80,000 mm at 25°C. 2 / s.

[0013] Preferably, the mixing ratio of the filler and the hydroxyl-terminated polydimethylsiloxane is 1 to 5:10 by weight.

[0014] Preferably, the process of mixing the filler with hydroxyl-terminated polydimethylsiloxane includes the following steps: a) Place the hydroxyl-terminated polydimethylsiloxane in a mixing container and preheat it to 80℃~130℃; b) Under a vacuum of 0.08–0.09 MPa, the filler is gradually added to the hydroxyl-terminated polydimethylsiloxane; c) Mix at a stirring rate of 200-800 RPM for 2-3 hours until uniformly dispersed.

[0015] Preferably, the fineness value is determined using a scraper fineness meter.

[0016] Preferably, the scraper fineness gauge conforms to GB / T 1724 standard, with a measurement range of 0-50μm and a graduation value of 5μm; the fineness test operation includes the following steps: a) Dip an appropriate amount of the filler sample to be tested into the depth of the scraper groove; b) Hold the scraper horizontally on the upper part of the scraper with both hands, so that the scraper is in perpendicular contact with the surface of the polishing plate. Scrape from top to bottom at a uniform speed within 3 seconds to fill the groove with the sample. c) After the scraper is pulled across, immediately adjust the viewing angle to 15-30 degrees with the surface of the groove, observe the area in the groove where the particles are evenly exposed under light, and record the reading.

[0017] Preferably, the filler sample is baked at 150°C for 2 hours.

[0018] The beneficial effects of this invention compared to the prior art are as follows: 1. Simple operation: This invention adopts simple mixing, baking and fineness testing steps, without the need for complicated sample preparation and professional operating skills, which lowers the technical threshold and makes it easy for ordinary technicians to master and operate.

[0019] 2. Rapid detection: The entire detection process can be completed in about 3 hours, including 2 hours for sample preparation, 2 hours for baking, and about 30 minutes for fineness testing. This greatly shortens the detection cycle and improves detection efficiency, making it suitable for rapid screening and quality control of fillers.

[0020] 3. Low equipment requirements: This invention only requires conventional mixing equipment, constant temperature drying oven and scraper fineness meter, without the need for expensive professional analytical instruments, which reduces the testing cost and is suitable for use by small and medium-sized enterprises and production sites.

[0021] 4. Accurate and reliable results: This invention uses hydroxyl-terminated polydimethylsiloxane as the matrix material, which is highly correlated with the actual application environment of silicone sealant. The test results can accurately reflect the temperature resistance performance of the filler in silicone sealant, providing a reliable basis for formulation design and production.

[0022] 5. Clear judgment criteria: This invention uses a 5-micron change in fineness value before and after baking as the judgment criterion, which quantifies the evaluation index of the filler's temperature resistance performance, avoids the error of subjective judgment, and makes the results more objective and reliable.

[0023] 6. Wide range of applications: This invention is applicable to fillers for various types of silicone sealants, including but not limited to calcium carbonate, talc, kaolin, wollastonite, barium sulfate, and silica, and has strong versatility and practicality.

[0024] The table below compares the main performance differences between the present invention and existing methods for testing the temperature resistance of fillers: . Detailed Implementation

[0025] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. The technical solution of the present invention will be described in detail below with reference to embodiments, but the scope of protection is not limited thereto. Example 1

[0026] This embodiment proposes a method for testing the temperature resistance of calcium carbonate filler, which specifically includes the following steps: S1. Sample preparation: a) Take 100g of material with a viscosity of 50000mm 2 / s (25℃) of hydroxyl-terminated polydimethylsiloxane was placed in a mixing container and preheated to 100℃; b) Under a vacuum of 0.085 MPa, 30 g of nano-calcium carbonate (particle size of 80-100 nm) was gradually added to hydroxyl-terminated polydimethylsiloxane; c) Mix at a stirring rate of 500 RPM for 2.5 hours until uniformly dispersed to obtain the test sample.

[0027] S2, Initial Fineness Test: a) Clean the scraper fineness gauge (measuring range 0-50μm, graduation value 5μm) and scraper conforming to GB / T 1724 standard with gasoline, wipe them dry with cotton yarn, and then wipe them clean with chamois leather; b) Dip a glass rod into an appropriate amount of test sample and drip it into the depth of the scraper groove, filling the groove with a little remaining; c) Hold the scraper horizontally on the upper part of the scraper with both hands, so that the scraper is in perpendicular contact with the surface of the polishing plate. Scrape it from top to bottom at a uniform speed within 3 seconds, so that the sample fills the groove and leaves no residue on the plate. d) After the scraper has passed, immediately adjust the viewing angle to 20 degrees with the surface of the groove, observe the area in the groove where the particles are evenly exposed under light, and record the reading. e) Perform three parallel measurements, and take the arithmetic mean of two similar readings, recording it as L0=15μm.

[0028] S3, High-temperature baking: a) Place the test sample on a flat stainless steel tray, with the sample thickness controlled at 2mm; b) Place the tray in a constant temperature oven and bake at 150℃ for 2 hours, with a temperature control accuracy of ±2℃. During baking, the sample should be placed on a flat stainless steel tray, and the sample thickness should not exceed 3mm to ensure uniform heat conduction.

[0029] S4. Fineness test after baking: a) Remove the baked test sample and allow it to cool to room temperature; b) Test the fineness value of the baked sample using the same method as in step 2, and record it as L1=22μm.

[0030] S5. Result Determination: Calculate the change in fineness value before and after baking: ΔL = L1 - L0 = 22μm - 15μm = 7μm.

[0031] Since ΔL = 7μm > 5μm, it is determined that this nano-calcium carbonate filler will exhibit coarsening after high temperature, indicating poor temperature resistance.

[0032] The result judgment criteria are based on the principle that the agglomeration, structural changes, or surface property alterations of the filler under high-temperature conditions may lead to an increase in the fineness of the mixture. When the filler undergoes coarsening at high temperatures, its particles aggregate to form larger aggregates, resulting in an increase in the fineness value of the mixture. By comparing the changes in fineness values ​​before and after baking, the temperature resistance performance of the filler can be effectively evaluated. Example 2

[0033] This embodiment proposes a method for testing the temperature resistance of talc fillers, which specifically includes the following steps: S1. Sample preparation: a) Take 100g of material with a viscosity of 30000mm 2 / s (25℃) of hydroxyl-terminated polydimethylsiloxane is placed in a mixing container and preheated to 90℃; b) Under a vacuum of 0.08 MPa, 20 g of talc powder (particle size 5-10 μm) was gradually added to hydroxyl-terminated polydimethylsiloxane; c) Mix at a stirring rate of 400 RPM for 2 hours until uniformly dispersed to obtain the test sample.

[0034] S2, Initial Fineness Test: The initial fineness value was tested according to the method in step 2 of Example 1 and recorded as L0 = 20 μm.

[0035] S3, High-temperature baking: Perform high-temperature baking treatment according to the method in step 3 of Example 1.

[0036] S4. Fineness test after baking: The fineness value of the baked sample was tested according to the method in step 2 of Example 1, and recorded as L1=23μm.

[0037] S5. Result Determination: Calculate the change in fineness value before and after baking: ΔL = L1 - L0 = 23μm - 20μm = 3μm.

[0038] Since ΔL = 3μm < 5μm, this talc filler is judged to have good temperature resistance. Example 3

[0039] This embodiment proposes a method for testing the temperature resistance of silica filler, which specifically includes the following steps: S1. Sample preparation: a) Take 100g of material with a viscosity of 80000mm 2 / s (25℃) of hydroxyl-terminated polydimethylsiloxane was placed in a mixing container and preheated to 120℃; b) Under a vacuum of 0.09 MPa, 40 g of fumed silica (with a specific surface area of ​​200 m²) was added. 2 (g) is gradually added to hydroxyl-terminated polydimethylsiloxane; c) Mix at a stirring rate of 600 RPM for 3 hours until uniformly dispersed to obtain the test sample.

[0040] S2, Initial Fineness Test: The initial fineness value was tested according to the method in step 2 of Example 1 and recorded as L0 = 10 μm.

[0041] S3, High-temperature baking: Perform high-temperature baking treatment according to the method in step 3 of Example 1.

[0042] S4. Fineness test after baking: The fineness value of the baked sample was tested according to the method in step 2 of Example 1, and recorded as L1=12μm.

[0043] S5. Result Determination: Calculate the change in fineness value before and after baking: ΔL = L1 - L0 = 12μm - 10μm = 2μm.

[0044] Since ΔL = 2μm < 5μm, this fumed silica filler is judged to have good temperature resistance. Example 4

[0045] Comparative test of temperature resistance of different fillers To verify the reliability of the method of this invention, six commonly used silicone sealant fillers were selected for temperature resistance comparison tests, and the results are shown in the table below: ; As can be seen from the table above, different types of fillers exhibit significant differences in stability under high-temperature conditions. Nano-calcium carbonate and kaolin, after baking at 150℃ for 2 hours, showed a fineness change exceeding 5 micrometers, indicating that these two fillers are prone to coarsening at high temperatures and have poor temperature resistance. In contrast, talc, fumed silica, wollastonite, and barium sulfate all showed fineness changes of less than 5 micrometers, indicating that these four fillers possess better temperature resistance. This result is largely consistent with the performance of these fillers in actual silicone sealants, verifying the reliability and practicality of the method of this invention. Example 5

[0046] The effect of different baking temperatures on test results To investigate the effect of baking temperature on the test results, nano-calcium carbonate filler was selected and baked at different temperatures. The results are shown in the table below: ; As shown in the table above, the fineness value of the nano-calcium carbonate filler gradually increases with increasing baking temperature. Baking at 100℃ and 130℃ for 2 hours resulted in fineness changes of less than 5 micrometers, indicating good temperature resistance. However, at 150℃ and 180℃, the fineness changes exceeded 5 micrometers, indicating poor temperature resistance. This result demonstrates that the temperature resistance of the filler is closely related to temperature, and the 150℃ baking condition selected in this invention effectively distinguishes the differences in the temperature resistance of the filler, making it a suitable testing temperature. Example 6

[0047] Effect of different baking times on test results To investigate the effect of baking time on the test results, nano-calcium carbonate filler was selected and baked at 150℃ for different times. The results are shown in the table below: ; As shown in the table above, the fineness value of the nano-calcium carbonate filler gradually increases with the extension of baking time. Under the conditions of 0.5 hours and 1 hour, the fineness value change is less than 5 micrometers, indicating good temperature resistance; while under the conditions of 2 hours and 4 hours, the fineness value change exceeds 5 micrometers, indicating poor temperature resistance. This result indicates that the temperature resistance of the filler is closely related to the baking time, and the 2-hour baking time selected in this invention can effectively distinguish the differences in the temperature resistance performance of the filler, making it a suitable testing time. Example 7

[0048] The Influence of Different Matrix Material Viscosities on Test Results To investigate the effect of matrix material viscosity on the test results, hydroxyl-terminated polydimethylsiloxanes with different viscosities were mixed with nano-calcium carbonate fillers for testing. The results are shown in the table below: ; As can be seen from the table above, within the viscosity range of 10000-80000 mm² / s, the viscosity of hydroxyl-terminated polydimethylsiloxane has little impact on the temperature resistance test results of nano-calcium carbonate fillers; the fineness value changes by 7 micrometers in all cases, which is considered as poor temperature resistance. This result indicates that the method of the present invention can obtain stable test results over a wide range of matrix material viscosity, demonstrating strong applicability. Example 8

[0049] The effect of different filler ratios on test results To investigate the effect of filler ratio on the test results, different ratios of nano-calcium carbonate filler were mixed with hydroxyl-terminated polydimethylsiloxane for testing. The results are shown in the table below: ; As shown in the table above, the fineness value of the nano-calcium carbonate filler gradually increases with the increase of the filler ratio. Under filler ratios of 10 and 20 parts, the fineness value change is less than or equal to 5 micrometers, indicating good temperature resistance; while under filler ratios of 30 and 40 parts, the fineness value change exceeds 5 micrometers, indicating poor temperature resistance. This result indicates that the temperature resistance of the filler is closely related to the filler ratio, and an appropriate filler ratio should be selected according to needs in practical applications. The ratio range of 10-50 parts filler to 100 parts hydroxyl-terminated polydimethylsiloxane recommended in this invention can effectively distinguish the differences in the temperature resistance performance of the fillers.

[0050] The above embodiments demonstrate that the temperature resistance testing method for silicone sealant fillers provided by this invention is simple to operate, rapid in testing, and accurate in yielding results. It can effectively assess the stability of fillers under high-temperature environments, providing technical support for the formulation design and production of silicone sealants. This method is applicable to various types of silicone sealant fillers and has strong versatility and practicality.

[0051] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0052] The detailed descriptions listed above are merely specific descriptions of feasible implementation methods of this application and are not intended to limit the scope of protection of this application. All equivalent implementation methods or modifications made without departing from the spirit of the art of this application should be included within the scope of protection of this invention.

Claims

1. A method for testing the temperature resistance of fillers used in silicone sealants, characterized in that, Includes the following steps: S1. Measure the initial fineness value of the filler sample and record it as L0; S2. Bake the filler sample at 150~180℃ for 2~4 hours; S3. Measure the fineness value of the filler sample after baking and record it as L1; If L1-L0≥5μm, the filler sample is judged to have coarsening after high temperature and has poor temperature resistance; if L1-L0<5μm, the filler sample is judged to have good temperature resistance.

2. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 1, characterized in that, The filler sample is a mixture of filler and hydroxyl-terminated polydimethylsiloxane.

3. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 2, characterized in that, The hydroxyl-terminated polydimethylsiloxane has a viscosity of 2000-1000000 mm at 25°C. 2 / s.

4. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 3, characterized in that, The viscosity of the hydroxyl-terminated polydimethylsiloxane at 25°C is 10,000–80,000 mm. 2 / s.

5. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 2, characterized in that, The filler and hydroxyl-terminated polydimethylsiloxane are mixed in a ratio of 1 to 5:10 by weight.

6. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 2, characterized in that, The process of mixing the filler with hydroxyl-terminated polydimethylsiloxane includes the following steps: a) Place the hydroxyl-terminated polydimethylsiloxane in a mixing container and preheat it to 80℃~130℃; b) Under a vacuum of 0.08–0.09 MPa, the filler is gradually added to the hydroxyl-terminated polydimethylsiloxane; c) Mix at a stirring rate of 200-800 RPM for 2-3 hours until uniformly dispersed.

7. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 1, characterized in that, Fineness values ​​were determined using a scraper fineness gauge.

8. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 7, characterized in that, The scraper fineness gauge conforms to GB / T 1724 standard, with a measurement range of 0-50μm and a graduation value of 5μm; the fineness test operation includes the following steps: a) Dip an appropriate amount of the filler sample to be tested into the depth of the scraper groove; b) Hold the scraper horizontally on the upper part of the scraper with both hands, so that the scraper is in perpendicular contact with the surface of the polishing plate. Scrape from top to bottom at a uniform speed within 3 seconds to fill the groove with the sample. c) After the scraper is pulled across, immediately adjust the viewing angle to 15-30 degrees with the surface of the groove, observe the area in the groove where the particles are evenly exposed under light, and record the reading.

9. The method for testing the temperature resistance of fillers for organosilicon sealants according to claim 1, characterized in that, The filler sample was baked at 150°C for 2 hours.