Analysis Method for Inorganic Filler Composition and Content in an Epoxy Resin Insulating Material

Abstract

The present invention discloses an analytical method for the inorganic filler components and content in an epoxy resin insulating material, comprising the following steps: performing thermogravimetric analysis on a sample of the epoxy resin insulating material, setting the heating rate at 10-20 K / min under a nitrogen atmosphere, heating from 40 °C to 500-550 °C, and then maintaining a constant temperature for 5-30 min; switching to an oxygen atmosphere, with a heating rate of 10-20 K / min, heating to 620-700 °C to obtain pyrolysis products and a thermogravimetric curve; determining the pyrolysis weight loss ratio, carbon ratio, and inorganic filler ratio according to the thermogravimetric curve; performing microscopic characterization and energy spectrum analysis on the pyrolysis products to obtain microscopic characterization results and energy spectrum analysis results, and combining with the thermogravimetric analysis results, the inorganic filler components and content in the epoxy resin insulating material can be judged. The analytical method of the present invention can accurately and efficiently analyze the inorganic filler components and content in epoxy resin.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical test analysis, and particularly relates to a method for analyzing the inorganic filler components and content in epoxy resin insulating materials. Background Art

[0002] Epoxy resin insulating materials are used for power equipment insulation due to their good insulation, high field strength, easy processing and other advantages, and are increasingly widely used in the power grid. At present, the preparation technology of epoxy resin insulating materials for high voltage levels has always been a "neck-sticking" technology that plagues the domestic materials industry, and epoxy resin insulating materials for high voltage levels mainly rely on imports. At present, the epoxy resin insulating materials produced in China are mainly for low voltage levels, but breakdown events of epoxy resin insulating materials occur from time to time. The structure and composition of materials determine their properties. Epoxy resin insulating materials are mainly composed of organic components and inorganic components. The organic components are basically the same, and the difference lies in the inorganic component composition and content. Therefore, it is very important to study the inorganic filler content and composition in epoxy resin insulating materials, but the current methods cannot achieve this. Summary of the Invention

[0003] The primary object of the present invention is to overcome the disadvantages and deficiencies of the prior art and provide a method for analyzing the inorganic filler components and content in epoxy resin insulating materials.

[0004] The object of the present invention is achieved by the following technical solutions: A method for analyzing the inorganic filler components and content in epoxy resin insulating materials, comprising the following steps:

[0005] (1) Perform thermogravimetric analysis (TGA) on the epoxy resin insulating material sample. Set the heating rate to 10-20 K / min in a nitrogen atmosphere, heat from 40 to 500-550 °C, and then keep it at a constant temperature for 5-30 min; switch to an oxygen atmosphere, with a heating rate of 10-20 K / min, and heat to 620-700 °C to obtain pyrolysis products and a thermogravimetric curve; determine the pyrolysis weight loss ratio, carbon ratio, and inorganic filler ratio according to the thermogravimetric curve;

[0006] (2) Perform microscopic characterization and energy spectrum analysis on the pyrolysis products in step (1) to obtain microscopic characterization results and energy spectrum analysis results. Combining with the thermogravimetric analysis results, the inorganic filler components and content in the epoxy resin insulating material can be judged.

[0007] Preferably, the nitrogen flow rate in the nitrogen atmosphere in step (1) is 20-50 mL / min; more preferably, the nitrogen flow rate in the nitrogen atmosphere is 50 mL / min.

[0008] Preferably, the oxygen flow rate in the oxygen atmosphere in step (1) is 20-50 mL / min; more preferably, the oxygen flow rate in the oxygen atmosphere is 50 mL / min.

[0009] Preferably, the epoxy resin sample in step (1) is obtained by the following method: cutting the epoxy resin insulating material into sheets and then wiping it clean.

[0010] Preferably, the microscopic characterization in step (2) is realized by a scanning electron microscope to obtain the microscopic morphology of the sample.

[0011] Preferably, the energy spectrum analysis in step (2) is realized by an energy spectrum analyzer to verify whether the pyrolysis reaction is complete and determine the types and contents of inorganic filler elements.

[0012] Thermogravimetric analysis can only analyze the approximate content of inorganic components and cannot analyze the types of inorganic components. After thermogravimetric analysis, scanning electron microscopy energy spectroscopy can further determine whether the organic components are completely pyrolyzed and analyze the types and contents of inorganic filler elements. Without thermogravimetric analysis, the surface of the epoxy resin insulating material is covered by organic components, and the types and contents of inorganic filler elements cannot be directly analyzed by scanning electron microscopy energy spectroscopy. Only by combining these two methods can the accurate types and contents of inorganic components be given. In addition, under the thermogravimetric analysis conditions of the present invention, the organic components are pyrolyzed into gaseous substances at high temperature and discharged with the carrier gas, which can maintain the morphology of inorganic components to the greatest extent.

[0013] In the analysis method of the present invention, oxygen will accelerate the reduction of the sample mass during thermogravimetric analysis and interfere with the pyrolysis curve. Therefore, it is necessary to set the switching of the gas atmosphere within a reasonable temperature range. Switching the gas atmosphere at different temperatures will affect the proportions of the organic part, carbon black, and inorganic filler, and the impact on the measurement results is also significant. Therefore, a specific switching temperature needs to be adopted.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] In the analysis method of the present invention, the organic components in the material are first pyrolyzed sufficiently by thermogravimetric analysis, then the carbon deposit is burned, and the weight of the remaining components is the content of inorganic components. Then, the powder substance remaining in the crucible after the thermogravimetric test is analyzed by scanning electron microscopy and energy spectroscopy to obtain the types and contents of inorganic filler elements, so as to judge the type of inorganic components. The analysis method of the present invention can accurately and efficiently analyze the inorganic filler components and contents in epoxy resin. Description of the Drawings

[0016] Figure 1 is the thermogravimetric curve in Example 1.

[0017] Figure 2 is the scanning electron micrograph in Example 1.

[0018] Figure 3 is the energy spectrum analysis chart in Example 1

[0019] Figure 4 It is the thermogravimetric curve in Comparative Example 1.

[0020] Figures 5-9 They are the thermogravimetric curves of switching gases at 240 °C, 550 °C, 600 °C, 700 °C, and 750 °C in Comparative Example 2 in sequence.

[0021] Figure 10 It is the thermogravimetric curve in Comparative Example 3.

[0022] Figure 11 It is the thermogravimetric curve with the highest heating temperature of 620 °C in Example 2.

[0023] Figure 12 It is the thermogravimetric curve with the highest heating temperature of 700 °C in Example 2.

[0024] Figure 13 It is the scanning electron micrograph in Example 2.

[0025] Figure 14 It is the energy spectrum analysis diagram in Example 2.

[0026] Figures 15-18 They are the thermogravimetric curves of the repeatability tests of the natural color EPGC308 epoxy glass cloth laminate (thickness 2 mm), natural color F881A epoxy glass cloth laminate (thickness 5 mm), natural color F882A epoxy glass cloth laminate (thickness 4 mm), and white SMC epoxy glass cloth laminate cut blocks (thickness 5 mm) in Example 4 in sequence.

[0027] Figure 19 It is the thermogravimetric curve in Example 5.

[0028] Figure 20 It is the scanning electron micrograph in Example 5.

[0029] Figure 21 It is the energy spectrum analysis diagram in Example 5. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0031] The epoxy glass cloth laminates in the following examples and comparative examples are all purchased from Beijing Furunda Chemical Co., Ltd.

[0032] Example 1

[0033] Cut the white SMC epoxy glass cloth laminate (with a thickness of 5 mm) into pieces, and wipe it with dust removal paper or lint-free cloth to obtain an insulating material sample. Weigh 10 mg of the sample and put it into a crucible on the tray of a thermogravimetric analyzer. The parameters of the thermogravimetric analyzer are as follows: nitrogen flow rate is 50 mL / min, heating rate is 20 K / min, temperature range is 40 °C to 500 °C, keep it at a constant temperature for 5 minutes after heating to 500 °C; switch to an oxygen atmosphere, oxygen flow rate is 50 mL / min, heating rate is 20 K / min, from 500 °C to 620 °C, to obtain pyrolysis products and a thermogravimetric curve. The thermogravimetric curve is as Figure 1 shown. Determine the pyrolysis weight loss ratio, carbon ratio and inorganic filler ratio according to the thermogravimetric curve. The results are shown in Table 1 below.

[0034] Analyze the pyrolysis products after thermogravimetric analysis by scanning electron microscopy and energy spectrum analysis to obtain the microscopic morphology and energy spectrum analysis results of the sample. The microscopic morphology is as Figure 2 shown, and the energy spectrum analysis results are as Figure 3 and Table 2 shown. Combining with the thermogravimetric analysis results, it can be judged that the organic components are completely removed, and the remaining white inorganic components are fibrous. The main elements are silicon, calcium and aluminum, etc. That is, the inorganic components in the SMC epoxy glass cloth laminate belong to glass fibers.

[0035] Table 1 Detection results of component content of materials

[0036]

[0037]

[0038]

[0039] Table 2 Energy spectrum analysis results

[0040]

[0041]

[0042] Comparative Example 1

[0043] Conduct thermogravimetric analysis on the white SMC epoxy glass cloth laminate of Example 1 in pure nitrogen and pure oxygen atmospheres respectively, with a temperature range of 40 °C to 800 °C, and keep other steps and parameter conditions unchanged. The thermogravimetric curve is as Figure 4 shown. At the initial stage, the temperature is relatively low, and the type of gas has no obvious influence on the thermogravimetric curve; after 300 °C, the mass change rate of the sample after introducing oxygen is faster, and the percentage of the residue at the end of the thermogravimetric curve is lower than that in the pure nitrogen atmosphere, indicating that oxygen accelerates the reduction of the sample mass and will interfere with the pyrolysis curve. Therefore, it is necessary to set the switching of the gas atmosphere within a suitable temperature range.

[0044] Comparative Example 2

[0045] During the analysis of the white SMC epoxy glass cloth laminate in Example 1, the temperature for switching the nitrogen atmosphere to an oxygen atmosphere was changed from 500 °C to 240 °C, 550 °C, 600 °C, 700 °C, and 750 °C, with the temperature range being 40 °C to 800 °C. Other steps and parameter conditions remained unchanged. The results are as follows Figures 5-9 shown. When switching to oxygen at 240 °C, the cracking and oxidation reactions occurred simultaneously at this time, interfering with the determination of the content of the sample components; when switching to oxygen at 550 °C, the remaining carbon black reacted rapidly with oxygen after introducing oxygen. It is worth noting that there was a step around 650 °C, presumably due to the decomposition of inorganic additives at high temperature, and this substance did not react with oxygen; when switching to oxygen at 600 °C, there was still a step around 650 °C after the oxidation reaction was completed; when switching to oxygen at 700 °C, the oxidation reaction and the cracking of inorganic additives occurred simultaneously; when switching to oxygen at 750 °C, the curve showed that before switching to oxygen, the inorganic additives decomposed around 650 °C, and the cracking of this part of the substance was only related to temperature, and the remaining substances did not decompose after the oxidation reaction occurred. Therefore, in order to study the proportions of the organic part, carbon black, and inorganic filler, it is sufficient to switch the oxygen atmosphere at 500 - 550 °C, and the maximum temperature can be heated to within 620 °C.

[0046] Comparative Example 3

[0047] The white SMC epoxy glass cloth laminate in Example 1 was kept at a constant temperature of 500 °C for 30 minutes under a nitrogen atmosphere, with other steps and parameter conditions remaining unchanged. The obtained thermogravimetric curve is as follows Figure 10 shown. The curve indicates that the decomposition of the material was completed after 5 minutes of keeping at a constant temperature of 500 °C under a nitrogen atmosphere, and there was no need to keep at a constant temperature for a longer time.

[0048] Example 2

[0049] The brown F882A.2 epoxy glass cloth laminate (thickness 4 mm) was cut into pieces and wiped with dust removal paper or lint-free cloth to obtain insulation material samples. The samples were placed in a crucible on the tray of a thermogravimetric analyzer. The parameters of the thermogravimetric analyzer were: nitrogen flow rate 50 mL / min, heating rate 10 K / min, from 40 °C to 500 °C, and kept at a constant temperature of 500 °C for 5 minutes after heating to 500 °C; then switched to an oxygen atmosphere, oxygen flow rate 50 mL / min, heating rate 20 K / min, from 500 °C to 700 °C. The thermogravimetric curve of heating to 620 °C is as follows Figure 11 shown. The thermogravimetric curve of heating to 700 °C is as follows Figure 12As shown. The thermogravimetric curves at two highest heating temperatures show that when heated to 620 °C, the TGA curve has not leveled off, that is, the duration of the oxidation reaction is relatively long. When heated to 620 °C, the reaction has not been completely finished. When heated to 700 °C, the reaction ends, obtaining pyrolysis products and thermogravimetric curves. According to the thermogravimetric curves Figure 12 the pyrolysis weight loss ratio, carbon ratio and inorganic filler ratio are determined, and the results are shown in Table 1 above.

[0050] The pyrolysis products after thermogravimetric analysis are analyzed by scanning electron microscopy and energy spectrum analysis to obtain the microscopic morphology and energy spectrum analysis results of the samples. The microscopic morphology is as Figure 13 shown, and the energy spectrum analysis results are as Figure 14 and Table 3 shown. Combining the thermogravimetric analysis results, it can be judged that the organic components are completely removed, and the remaining white inorganic components are fibrous, and the elements mainly include silicon, calcium and aluminum, etc. That is, the inorganic components in the brown F882A.2 epoxy glass cloth laminate belong to glass fibers.

[0051] Table 3 Energy spectrum analysis results

[0052]

[0053]

[0054] Example 3

[0055] Other typical epoxy resin insulating materials such as white GPO-3 epoxy glass cloth laminate, natural color 3240 epoxy glass cloth laminate, natural color F880A epoxy glass cloth laminate, natural color F861A epoxy glass cloth laminate, natural color F861A epoxy glass cloth laminate are analyzed by the same analysis method as in Example 1 to obtain pyrolysis products and thermogravimetric curves. The pyrolysis weight loss ratio, carbon ratio and inorganic filler ratio are determined according to the thermogravimetric curves, as shown in Table 1 above.

[0056] The pyrolysis products after thermogravimetric analysis are analyzed by scanning electron microscopy and energy spectrum analysis to obtain the microscopic morphology and energy spectrum analysis results of the samples. Combining the thermogravimetric analysis results, it can be judged that the organic components are completely removed, and the remaining white inorganic components are fibrous, and the elements mainly include silicon, calcium and aluminum, etc. That is, the inorganic components in the brown F882A.2 epoxy glass cloth laminate belong to glass fibers.

[0057] Example 4

[0058] Repeatability TGA tests are carried out on the cut pieces (thickness 5 mm) of natural color EPGC308 epoxy glass cloth laminate (thickness 2 mm), natural color F881A epoxy glass cloth laminate (thickness 5 mm), natural color F882A epoxy glass cloth laminate (thickness 4 mm) and white SMC epoxy glass cloth laminate. The method is the same as that in Example 1, and the analysis results are as Figures 15-18As shown. The results show that the repeatability of the thermogravimetric analysis method for the detection results is good.

[0059] Example 5

[0060] The current transformer insulation component was analyzed using the same analysis method as in Example 1 to obtain pyrolysis products and a thermogravimetric curve. The thermogravimetric curve is as Figure 19 shown. The pyrolysis weight loss ratio, carbon ratio, and inorganic filler ratio were determined according to the thermogravimetric curve. The contents of each component are as follows: the content of the organic component is 26.3%, and the content of the inorganic filler component is 73.7%.

[0061] The pyrolysis products after thermogravimetric analysis were analyzed by scanning electron microscopy and energy spectrum analysis to obtain the microscopic morphology and energy spectrum analysis results of the samples. The microscopic morphology is as Figure 20 shown, and the energy spectrum analysis results are as Figure 21 and Table 4 shown. Combining the thermogravimetric analysis results, it can be judged that all the organic components are removed, and the remaining gray inorganic components are powdery, and the elements are mainly silicon and oxygen, etc. That is, the inorganic components in the current transformer insulation component belong to silicon dioxide powder.

[0062] Table 4 Energy Spectrum Analysis Results

[0063]

[0064] The above is the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present invention.

Claims

1. A method for analyzing the composition and content of inorganic fillers in an epoxy resin insulating material, characterized in that, It includes the following steps: (1) Conduct thermogravimetric analysis on the epoxy resin insulation material sample. Set the heating rate to 10 - 20 K / min in a nitrogen atmosphere, heat from 40 °C to 500 - 550 °C, and then keep it at a constant temperature for 5 - 30 min. Switch to an oxygen atmosphere, with a heating rate of 10 - 20 K / min, and heat to 620 - 700 °C to obtain pyrolysis products and a thermogravimetric curve. Determine the pyrolysis weight loss ratio, carbon ratio, and inorganic filler ratio based on the thermogravimetric curve; the inorganic filler in the epoxy resin insulation material is glass fiber or silica; (2) Conduct microscopic characterization and energy spectrum analysis on the pyrolysis products obtained in step (1) to obtain microscopic characterization results and energy spectrum analysis results. Combining with the thermogravimetric analysis results, the composition and content of the inorganic filler in the epoxy resin insulation material can be determined.

2. The analysis method for the inorganic filler composition and content in the epoxy resin insulating material according to claim 1, characterized in that, The epoxy resin sample in step (1) is obtained by the following method: Cut the epoxy resin insulation material into sheets and then wipe it clean.

3. The analytical method for the inorganic filler components and contents in the epoxy resin insulating material according to claim 1, characterized in that, The microscopic characterization in step (2) is achieved by a scanning electron microscope to obtain the microscopic morphology of the sample.

4. The analytical method for the inorganic filler composition and content in the epoxy resin insulating material according to claim 1, wherein The energy spectrum analysis in step (2) is achieved by an energy spectrum analyzer to verify whether the reaction is complete and determine the types and contents of inorganic filler elements.

5. The analytical method for the inorganic filler components and contents in the epoxy resin insulating material according to claim 1, wherein The nitrogen flow rate in the nitrogen atmosphere in step (1) is 20 - 50 mL / min.

6. The analysis method for the inorganic filler composition and content in the epoxy resin insulating material according to claim 1, characterized in that, The oxygen flow rate in the oxygen atmosphere in step (1) is 20 - 50 mL / min.

7. The analytical method for the inorganic filler components and contents in the epoxy resin insulating material according to claim 5, wherein The nitrogen flow rate in the nitrogen atmosphere in step (1) is 50 mL / min.

8. The analytical method for the inorganic filler components and contents in the epoxy resin insulating material according to claim 6, characterized in that, The oxygen flow rate in the oxygen atmosphere in step (1) is 50 mL / min.

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