Method for testing curing degree of electromagnetic wire

Abstract

The invention discloses a method for testing the curing degree of an electromagnetic wire, and relates to the technical field of paint film test.The method comprises the following steps that firstly, a paint film on a PI paint electromagnetic wire is taken down; step 2, carrying out normal-temperature ultrasonic treatment on the paint film by a trichloromethane solution for 3 hours, and filtering to obtain an extract; step 3, loading, and setting GCMS parameters; step 4, acquiring chromatograms of NMP and DMAC and chromatograms of o-cresol and m-cresol; and step 5, determining the residual quantity of the solvent according to the NMP and DMAC chromatograms and the o-cresol and m-cresol chromatograms, determining the curing degree of the electromagnetic wire according to the residual quantity of the solvent, and more accurately evaluating the volatilization degree of the solvent in the baking process by directly detecting the residual quantity of the solvent in the enameled wire so as to judge whether the baking process is sufficient or not. Compared with dielectric loss analysis, the detection of the residual amount of the solvent is more direct, and the baking state of the enameled wire can be reflected more accurately.

Description

Technical Field

[0001] The invention relates to the technical field of paint film testing, and more particularly to a method for testing the curing degree of electromagnetic wires. Background Art

[0002] NMP, DMAC and cresol are solvents that must be used in the production process of insulating varnish.

[0003] The solvent evaporation and curing degree of the paint have a great influence on the quality of the electromagnetic wire. The solvent contained in the enameled wire paint is only added for the needs of the painting process. No solvent is allowed to exist in the paint film, and the solvent does not participate in the chemical reaction of the paint-based resin molecules. Therefore, the solvent in the paint applied to the wire in the baking oven must escape from the paint film at a certain temperature.

[0004] After the wire is painted, it enters the drying oven, where the solvent in the paint liquid evaporates, and the paint base undergoes physical and chemical changes such as cross-linking and cracking to form a paint film.

[0005] Baking is a key process in the production of enameled wires, such as the physical and chemical changes of the paint in the oven, the catalytic combustion hot air circulation system, etc., from which the process control requirements of the baking process are summarized. The paint liquid undergoes physical and chemical changes in the oven. The paint liquid applied on the wire must be baked in the oven. Under the action of high temperature, the solvent of the paint liquid first evaporates, and then the paint-based resin undergoes a chemical reaction, mainly cross-linking or decomposition, to complete the curing of the paint film. In these processes, the resin will also be cracked. Modern technology has developed dielectric loss analysis for the analysis of the baking degree of enameled wires, which can quickly formulate monitoring and analysis of whether the baking process of the enameled wire and the running process are appropriate. However, with the development of enameled wire technology, relying solely on dielectric loss analysis is not enough to judge the baking process of the enameled wire. The present invention uses the residual solvent to measure the baking process of the enameled wire. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for testing the curing degree of electromagnetic wire.

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for testing the curing degree of electromagnetic wire comprises the following steps: Step 1: Remove the paint film on the PI paint electromagnetic wire; Step 2: The paint film is subjected to ultrasonic treatment in a chloroform solution at room temperature for 3 hours, and the extract is filtered to obtain the extract; Step 3: Go on the machine and set the GCMS parameters; Step 4: Obtain NMP, DMAC chromatograms as well as o-cresol and m-cresol chromatograms; Step 5: Determine the residual solvent amount according to the chromatograms of NMP, DMAC and o-cresol and m-cresol, and determine the curing degree of the electromagnetic wire according to the residual solvent amount.

[0008] Further, the NMP and DMAC chromatograms were obtained by the following method: 0.0156 g of NMP standard was placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with a methanol solution to obtain a 1560 ppm NMP mother solution. 0.0139 g of DMAC standard was placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with a methanol solution to obtain a 1390 ppm DMAC mother solution. 1.282 ml of NMP mother solution and 1.439 ml of DMAC mother solution were placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with a chloroform solution to obtain a 200 ppm intermediate solution. The GCMS parameters were: injection port temperature: 280 ° C; split mode, split ratio: 50:1; program temperature rise: 40 ° C for 2 min, 20 ° C / min to 280 ° C, and kept for 5 min; mass spectrometry settings: ion source temperature: 280 ° C, transmission line temperature: 280 ° C; Basic information of the chromatographic column: length 30m, diameter 0.250mm, film thickness 0.25μm; Sample collection method: SCAN method is used for collection; NMP standard working curve: retention time: 6.77min, Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, x is the concentration (mg / L); C1=1154328.066, C0=-567638.2323, determination coefficient 0.995, relative standard deviation: 9.3147%; DMAC standard working curve: retention time: 5.19min; Y=C1*x+C0, Y is the peak area of ​​the peak, C1 is the slope, C0 is the intercept, x is the concentration (mg / L), C1=2060045.228, C0=-292723.058, determination coefficient 0.999, relative standard deviation: 3.1096%.

[0009] Further, the chromatograms of o-cresol and m-cresol were obtained by the following method: 0.0197 g of o-cresol standard was placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with chloroform solution to obtain a 1970 ppm o-cresol mother solution; 0.0135 g of m-cresol standard was placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with chloroform solution to obtain a 1350 ppm m-cresol mother solution; 1.015 ml of o-cresol mother solution and 1.481 ml of m-cresol mother solution were respectively placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with chloroform solution to obtain a 200 ppm intermediate solution; GCMS parameters were as follows: injection port temperature: 280°C; split mode, split ratio: 50:1; program temperature rise: 40°C for 2 min, 20°C / min to 280°C, hold for 5 min; mass spectrometer settings: ion source temperature: 280°C, transfer line temperature: 280°C; Basic information of the chromatographic column: length 30m, diameter 0.250mm, film thickness 0.25μm; Sample collection method: SCAN method is used for collection; Standard working curve of o-cresol: retention time: 6.89min, Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, x is the concentration (mg / L), C1=1157968.625 C0=-328969.3959, determination coefficient 0.998, relative standard deviation: 4.4740%; Standard working curve of meta-cresol: retention time: 7.06min, Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, x is the concentration (mg / L), C1=1165243.819 C0=-406751.5306, determination coefficient 0.998, relative standard deviation: 5.0403%.

[0010] Compared with the prior art, the present invention has the following beneficial effects: The present invention can more accurately evaluate the degree of solvent volatilization during the baking process by directly detecting the residual amount of solvent in the enameled wire, thereby judging whether the baking process is sufficient. Compared with the dielectric loss analysis, the detection of the residual amount of solvent is more direct and can more accurately reflect the baking state of the enameled wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is the chromatogram of NMP and DMAC; Figure 2 This is the chromatogram of o-cresol and m-cresol. DETAILED DESCRIPTION

[0012] Reference Figure 1-Figure 2 Taking PI painted electromagnetic wire as an example, the solvent residues of PI paint currently concerned are: NMP / DMAC / cresol (o-cresol, m-cresol, p-cresol). In the future, more substances may be concerned, not limited to the above three, and electromagnetic wire is not limited to polyimide imide painted electromagnetic wire.

[0013] Preparation of NMP, DMAC standard substance solution and working curve: 1. Preparation of mother solution 1. Take 0.0156g of NMP standard in a 10ml volumetric flask and dilute to 10ml with methanol solution (HPLC grade) to obtain 1560ppm NMP mother solution.

[0014] 2. Take 0.0139g of DMAC standard in a 10ml volumetric flask and dilute to 10ml with methanol solution (HPLC grade) to obtain 1390ppm DMAC mother solution.

[0015] 2. Preparation of NMP & DMAC mixed intermediate solution (200 mg / L) Take 1.282 ml of NMP mother solution and 1.439 ml of DMAC mother solution respectively in a 10 ml volumetric flask and make up to 10 ml with chloroform solution (HPLC grade).

[0016] 3. Preparation of working curve 4. Gas Chromatography Mass Spectrometry (GCMS) Settings The GCMS parameters were as follows: injection port temperature: 280°C; split mode, split ratio: 50:1; programmed temperature: 40°C for 2 min, 20°C / min to 280°C, and hold for 5 min; mass spectrometry settings: ion source temperature: 280°C, transfer line temperature: 280°C.

[0017] Basic information of the chromatographic column: length 30m, diameter 0.250mm, film thickness 0.25μm.

[0018] Sample collection method: The data is collected using the SCAN method.

[0019] NMP standard working curve: Retention time: 6.77min.

[0020] Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, and x is the concentration (mg / L).

[0021] C1=1154328.066 C0=-567638.2323, determination coefficient 0.995, relative standard deviation: 9.3147%.

[0022] DMAC standard working curve: Retention time: 5.19min.

[0023] Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, and x is the concentration (mg / L).

[0024] C1=2060045.228 C0=-292723.058, determination coefficient 0.999, relative standard deviation: 3.1096%.

[0025] Preparation of cresol (o-cresol, m-cresol) standard substance solution and working curve: 1. Preparation of mother solution 1. Take 0.0197g of o-cresol standard in a 10ml volumetric flask and dilute to 10ml with chloroform solution (HPLC grade) to obtain 1970ppm o-cresol mother solution.

[0026] 2. Take 0.0135g of m-cresol standard in a 10ml volumetric flask and dilute to 10ml with chloroform solution (HPLC grade) to obtain 1350ppm m-cresol mother solution.

[0027] 2. Preparation of o-cresol & m-cresol mixed intermediate solution (200 mg / L) Take 1.015 ml of o-cresol mother solution and 1.481 ml of m-cresol mother solution respectively in a 10 ml volumetric flask and make up to 10 ml with chloroform solution (HPLC grade).

[0028] 3. Preparation of working curve 4. Gas Chromatography Mass Spectrometry (GCMS) Settings The GCMS parameters were as follows: injection port temperature: 280°C; split mode, split ratio: 50:1; programmed temperature: 40°C for 2 min, 20°C / min to 280°C, and hold for 5 min; mass spectrometry settings: ion source temperature: 280°C, transfer line temperature: 280°C.

[0029] Basic information of the chromatographic column: length 30m, diameter 0.250mm, film thickness 0.25μm.

[0030] Sample collection method: The data is collected using the SCAN method.

[0031] o-Cresol standard working curve: Retention time: 6.89min.

[0032] Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, and x is the concentration (mg / L).

[0033] C1=1157968.625 C0=-328969.3959, determination coefficient 0.998, relative standard deviation: 4.4740%.

[0034] Standard working curve of m-cresol: Retention time: 7.06min.

[0035] Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, and x is the concentration (mg / L).

[0036] C1=1165243.819 C0=-406751.5306, determination coefficient 0.998, relative standard deviation: 5.0403%.

[0037] Note: Since m-cresol and p-cresol elute at the same time and have the same mass-to-charge ratio, m-cresol is used to qualitatively and quantitatively analyze m-cresol and p-cresol. The final calculation of the residual amount of cresol is the sum of o-cresol and m-cresol.

[0038] The final residual solvent content is determined by the total value of several solvents.

[0039] Residual solvent content under three different process conditions.

[0040] The residual solvent content decreased by 31%: the electrical properties were slightly improved, the thermal properties remained unchanged, and the mechanical properties (elongation increased by 20%, and others remained unchanged).

[0041] The residual solvent content decreased by 73%: the electrical properties were slightly improved, the thermal properties were reduced, and the mechanical properties (elongation increased by 10%, winding was reduced, and other properties remained unchanged).

[0042] Therefore, the residual solvent content has a great influence on the curing degree of the paint film of the electromagnetic wire, and the curing degree of the paint film of the electromagnetic wire can be determined by testing the residual solvent content.

[0043] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for testing the curing degree of electromagnetic wire, characterized in that: The steps include: Step 1: Remove the paint film on the PI paint electromagnetic wire; Step 2: The paint film is subjected to ultrasonic treatment in a chloroform solution at room temperature for 3 hours, and the extract is obtained by filtration; Step 3: Go on the machine and set the GCMS parameters; Step 4: Obtain NMP, DMAC chromatograms as well as o-cresol and m-cresol chromatograms; Step 5: Determine the residual solvent amount according to the chromatograms of NMP, DMAC and o-cresol and m-cresol, and determine the curing degree of the electromagnetic wire according to the residual solvent amount.

2. A method for testing the curing degree of electromagnetic wire according to claim 1, characterized in that: NMP, DMAC chromatograms were obtained by the following method: 0.0156g NMP standard was placed in a 10ml volumetric flask, and the volume was adjusted to 10ml with methanol solution to obtain 1560ppm NMP mother solution, 0.0139g DMAC standard was placed in a 10ml volumetric flask, and the volume was adjusted to 10ml with methanol solution to obtain 1390ppm DMAC mother solution, 1.282ml NMP mother solution and 1.439ml DMAC mother solution were placed in a 10ml volumetric flask, and the volume was adjusted to 10ml with chloroform solution to obtain 200ppm intermediate solution, GCMS parameters were: injection port temperature: 280℃; split mode, split ratio: 50:1; program temperature rise: 40℃ for 2min, 20℃ / min to 280℃, and hold for 5min; mass spectrometer settings: ion source temperature: 280℃, transfer line temperature: 280℃; Basic information of the chromatographic column: length 30m, diameter 0.250mm, film thickness 0.25μm; Sample collection method: SCAN method is used for collection; NMP standard working curve: retention time: 6.77min, Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, x is the concentration (mg / L); C1=1154328.066, C0=-567638.2323, determination coefficient 0.995, relative standard deviation: 9.3147%; DMAC standard working curve: retention time: 5.19min; Y=C1*x+C0, Y is the peak area of ​​the peak, C1 is the slope, C0 is the intercept, x is the concentration (mg / L), C1=2060045.228, C0=-292723.058, determination coefficient 0.999, relative standard deviation: 3.1096%.

3. A method for testing the curing degree of electromagnetic wire according to claim 1, characterized in that: The chromatograms of o-cresol and m-cresol were obtained by the following method: 0.0197 g of o-cresol standard was placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with chloroform solution to obtain a 1970 ppm o-cresol mother solution; 0.0135 g of m-cresol standard was placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with chloroform solution to obtain a 1350 ppm m-cresol mother solution; 1.015 ml of o-cresol mother solution and 1.481 ml of m-cresol mother solution were respectively placed in a 10 ml volumetric flask, and the volume was adjusted to 10 ml with chloroform solution to obtain a 200 ppm intermediate solution; GCMS parameters were as follows: injection port temperature: 280°C; split mode, split ratio: 50:1; program temperature rise: 40°C for 2 min, 20°C / min to 280°C, hold for 5 min; mass spectrometer settings: ion source temperature: 280°C, transfer line temperature: 280°C; Basic information of the chromatographic column: length 30m, diameter 0.250mm, film thickness 0.25μm; Sample collection method: SCAN method is used for collection; Standard working curve of o-cresol: retention time: 6.89min, Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, x is the concentration (mg / L), C1=1157968.625 C0=-328969.3959, determination coefficient 0.998, relative standard deviation: 4.4740%; Standard working curve of meta-cresol: retention time: 7.06min, Y=C1*x+C0, Y is the peak area, C1 is the slope, C0 is the intercept, x is the concentration (mg / L), C1=1165243.819 C0=-406751.5306, determination coefficient 0.998, relative standard deviation: 5.0403%.

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