A test method, device and storage medium for evaluating film-forming rate of insulating paint

Abstract

A test method, device and storage medium for evaluating the film-forming rate of insulating paint, comprising the following steps: obtaining the solid content m of the insulating paint to be tested; performing thermogravimetric analysis on a standard paint film in an actual production process and a paint film to be tested after curing the insulating paint to be tested to obtain a thermogravimetric curve; determining whether the thermogravimetric curve of the paint film to be tested has a target inflection point that causes a certain curve segment to deviate from the thermogravimetric curve of the standard paint film, and obtaining the area ratio k of the deviated curve segment; and calculating the film-forming rate C=m×(1‑k) of the insulating paint to be tested. The present invention respectively tests the thermogravimetric curves of the insulating paint film during the production process and the insulating paint film after curing, uses the thermogravimetric curves to analyze the relationship between the solid content and the film-forming rate of the insulating paint, calculates the actual film-forming rate of the insulating paint, optimizes production costs, and provides a new test direction for the calculation method of the insulating paint film process quota. The method is simple to operate, highly applicable, and can be widely used in the calculation of the film-forming rates of different types of insulating paints.

Description

Technical Field

[0001] The invention relates to the technical field of enameled wires, in particular to a testing method, a device and a storage medium for evaluating the film-forming rate of insulating varnish. Background Art

[0002] Enameled wire primarily consists of a metal conductor and an insulating varnish film. The insulating varnish is formed by applying multiple thin coats of paint and then baking them. The solids content of the varnish is often used in process quotas to characterize the film-forming rate of enameled wire. The higher the solids content of the varnish, the more enameled wire can be produced per ton of varnish, and the higher the film-forming rate.

[0003] During the production process, statistics show that under the same production specifications, machines, and parameter settings, the actual output of enameled wire produced by insulating varnishes with the same solid content but from different manufacturers has certain differences. Currently, there is a lack of testing solutions for the solid content and actual film-forming rate of insulating varnishes on the market. Summary of the Invention

[0004] In response to the problem of lack of effective testing of the actual film-forming rate of different insulating varnishes with similar solid contents, the present invention provides a testing method, device and storage medium for evaluating the film-forming rate of insulating varnishes. By using the thermal gravimetric (DTG) curve, the relationship between the solid content of the insulating varnish to be tested and the actual film-forming rate is analyzed, providing an effective evaluation for the process quota of the enameled wire insulating varnish film and optimizing the production cost.

[0005] To achieve the above object, the present invention adopts the following technical solution: a test method for evaluating the film-forming rate of insulating paint, comprising the following steps:

[0006] Obtaining the solid content m of the insulating varnish to be tested;

[0007] Perform thermogravimetric analysis on the standard paint film in the actual production process and the paint film to be tested after curing of the insulating paint to be tested to obtain a thermogravimetric curve;

[0008] Determine whether there is a target inflection point in the thermal weight loss curve of the paint film to be tested, which causes a certain curve segment to deviate from the standard thermal weight loss curve of the paint film, and obtain the area ratio k of the deviated curve segment;

[0009] Calculate the film-forming rate C of the insulating varnish to be tested = solid content m × (1-area ratio k).

[0010] As a further improvement of the present invention: the step of obtaining the solid content m of the insulating varnish to be tested includes:

[0011] Take 1-2g of the insulating varnish to be tested and evenly distribute it in a container with a mass of m0. Measure the total mass m1 of the container and the insulating varnish to be tested before baking.

[0012] Bake the container evenly covered with the insulating paint to be tested at 180°C for 1 hour, and measure the total mass m2 of the container and the insulating paint to be tested after baking;

[0013] Calculate the solid content m = (m2-m0) / (m1-m0)×100%.

[0014] As a further improvement of the present invention: the standard paint film in the actual production process is a paint film that has been used in actual production and can meet actual production needs, the paint film to be tested after the insulating paint to be tested is a paint film formed by baking the insulating paint to be tested at 180°C for 1h, and the thermal gravimetric curve is a thermogravimetric differential curve.

[0015] As a further improvement of the present invention, the step of determining whether the thermal gravimetric loss curve of the paint film to be tested has a target inflection point so that a certain curve segment deviates from the standard thermal gravimetric loss curve of the paint film includes:

[0016] Obtaining multiple inflection points of the thermal weight loss curve of the paint film to be tested, and determining the trend of the curve segments where the multiple inflection points are located;

[0017] When the curve trend of a certain inflection point is different from the curve trend of the standard paint film thermal weight loss curve in the same temperature range, the inflection point is the target inflection point, which makes the certain curve segment deviate from the standard paint film thermal weight loss curve.

[0018] As a further improvement of the present invention: the inflection point is a concave-convex curve dividing point that changes the trend direction of the curve, and the trend direction of the curve includes one of the following: an upward trend direction of the curve, a horizontal trend direction of the curve, and a downward trend direction of the curve.

[0019] As a further improvement of the present invention, the method of obtaining the area ratio k of the deviated curve segment includes:

[0020] Determine the temperature interval of the deviated curve segment;

[0021] Obtaining the peak area s1 of the curve segment within the temperature range and the peak area s of the thermal gravimetric loss curve of the paint film to be tested within the preset temperature;

[0022] The area ratio of the deviated curve segment is calculated as k = s1 / s×100%.

[0023] As a further improvement of the present invention: the temperature interval of the curve segment for determining the deviation includes:

[0024] The starting end and the tail end of the curve segment obtained from the deviation correspond to two temperature values ​​on the horizontal temperature axis respectively, and the temperature interval between the two temperature values ​​is determined as the temperature interval for calculating the area ratio.

[0025] As a further improvement of the present invention: in calculating the area ratio of the deviated curve segment, the peak area of ​​the thermal gravimetric loss curve of the paint film to be tested within the preset temperature is used to represent the solid content of the insulating paint to be tested, and the peak area of ​​the curve segment within the temperature range is used to represent the content of low molecular weight substances volatilized within the temperature range.

[0026] The present invention also selects the following technical solution: a test device for evaluating the film-forming rate of insulating paint, comprising a memory and a processor, wherein the processor calls a control program stored in the memory to execute a test method for evaluating the film-forming rate of insulating paint as described above.

[0027] The present invention also selects the following technical solution: a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the processor executes a test method for evaluating the film-forming rate of insulating paint as described above.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This method measures the thermal gravimetric curves of insulating paint films during production and after curing. By calculating the proportions of each component at different weight loss temperatures, the actual film-forming rate of the insulating paint can be indirectly calculated, thereby optimizing production costs. Analyzing the relationship between the solids content and film-forming rate of insulating paint using thermal gravimetric curves provides a new testing method for calculating insulating paint film process quotas. This method is simple to operate and has strong applicability, making it widely applicable for calculating the film-forming rates of different types of insulating paints. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to illustrate the technical solution more clearly, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] Figure 1 It is a schematic diagram of the process of the present invention.

[0032] Figure 2 Schematic diagram of the process of the embodiment.

[0033] Figure 3 Schematic diagram of the thermogravimetric curve of the embodiment. DETAILED DESCRIPTION

[0034] In order to enable a clear and complete understanding of the technical solution, the present invention is further described in conjunction with the embodiments and drawings. Obviously, the described embodiments are only some embodiments of the present invention, and all other embodiments obtained by technical personnel in the relevant field without making creative work are within the scope of protection of the present invention.

[0035] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0036] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in the specification and appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0037] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0038] like Figure 1 As shown, a test method for evaluating the film-forming rate of insulating paint comprises the following steps:

[0039] Obtain the solid content m of the insulating varnish to be tested, including:

[0040] Take 1-2g of the insulating varnish to be tested and evenly distribute it in a container with a mass of m0. Measure the total mass m1 of the container and the insulating varnish to be tested before baking.

[0041] Bake the container evenly covered with the insulating paint to be tested at 180°C for 1 hour, and measure the total mass m2 of the container and the insulating paint to be tested after baking;

[0042] Calculate the solid content m = (m2-m0) / (m1-m0)×100%.

[0043] The standard paint film of the actual production process and the paint film to be tested after curing of the insulating paint to be tested are subjected to thermogravimetric analysis to obtain a thermogravimetric curve. The standard paint film of the actual production process is a paint film that has been used in actual production and can meet actual production needs. The paint film to be tested after curing of the insulating paint to be tested is a paint film formed by curing the insulating paint to be tested by baking at 180°C for 1 hour. The thermogravimetric curve is a thermogravimetric differential curve.

[0044] Thermogravimetric analysis is to place the sample under a certain temperature program (increase / decrease / constant temperature) control, observe the change process of the sample's mass with temperature or time, and obtain relevant information such as the weight loss ratio, weight loss temperature (starting point, peak value, end point...), and decomposition residue. During the test process, the high-precision balance connected to the lower part of the sample holder senses the current weight of the sample at any time and transmits the data to the computer, which draws a curve (TG curve) of the sample weight against temperature / time. The thermogravimetric curve of this embodiment is preferably a thermogravimetric differential curve (DTG curve), which is a further differential calculation of the TG curve, and can further obtain more information such as the weight change rate. When the paint film changes in weight, it will be reflected as a weight loss (or weight gain) step on the TG curve, from which the temperature region where the weight loss / weight gain process occurs can be known, and the weight loss / weight gain ratio can be quantitatively calculated. The thermogravimetric differential curve of this embodiment characterizes the change in the rate of change of the paint film weight with temperature, and its peak point characterizes the temperature point at which the weight change rate of each weight loss / weight gain step is the fastest. The peak of the thermogravimetric differential curve is the temperature point at which the mass change rate is the largest, corresponding to the inflection point on the TG curve.

[0045] Determine whether there is a target inflection point in the thermal gravimetric loss curve of the paint film to be tested, which causes a certain curve segment to deviate from the standard thermal gravimetric loss curve of the paint film, including:

[0046] Obtain multiple inflection points of the thermal gravimetric loss curve (DTG curve) of the paint film to be tested, wherein the inflection point is the concave-convex curve dividing point where the trend of the curve changes, that is, the connection point between the convex curve and the concave curve in the curve graph;

[0047] Determine a curve trend direction of a curve segment where multiple inflection points are located, wherein the curve trend direction includes one of the following: an upward trend direction of the curve, a horizontal trend direction of the curve, and a downward trend direction of the curve;

[0048] When the curve trend of a certain inflection point is different from the curve trend of the standard paint film thermal gravimetric curve in the same temperature range, the inflection point is the target inflection point, causing the certain curve segment to deviate from the standard paint film thermal gravimetric curve. Specifically, when the curve segment of the thermal gravimetric curve of the paint film to be tested is in a downward trend, while the curve segment of the thermal gravimetric curve of the standard paint film in the corresponding temperature range is in a horizontal trend of the curve of the horizontal extension path or an upward trend of the curve of the upward extension path, it is determined that the curve trends are different, and the inflection point on the curve segment is the target inflection point, causing the two thermal gravimetric curves to deviate from the path; similarly, when the curve segment of the thermal gravimetric curve of the paint film to be tested is in a downward trend, while the curve segment of the thermal gravimetric trend of the standard paint film in the corresponding temperature range is also in a downward trend, it means that the curve shapes and trends of the two paint films in a certain temperature range are basically the same, the inflection point does not belong to the target inflection point described in this embodiment, and the peak area of ​​the curve segment of the inflection point does not need to be included in the calculation of the film formation rate.

[0049] Obtain the area ratio k of the deviated curve segment, including:

[0050] Determine the temperature range of the deviated curve segment, obtain two temperature values ​​on the horizontal temperature axis corresponding to the start and end of the deviated curve segment, and determine the temperature range between the two temperature values ​​as the temperature range for calculating the area ratio;

[0051] The peak area s1 of the curve segment within the temperature range and the peak area s of the thermal gravimetric loss curve of the paint film to be tested at a preset temperature are obtained. The peak area of ​​the thermal gravimetric loss curve of the paint film to be tested at the preset temperature is used to represent the solids content of the tested insulating paint, and the peak area of ​​the curve segment within the temperature range is used to represent the content of low-molecular-weight substances volatilized within the temperature range. Generally, the temperature range should be higher than the temperature selected for curing the insulating paint to be tested. This is because most of the low-molecular-weight substances have already volatilized during the curing of the insulating paint. Higher temperatures can cause some low-molecular-weight substances that are not fully cured to volatilize, which is reflected on the thermal gravimetric loss curve as a deviation from the thermal gravimetric loss curve of the standard paint film. Therefore, if the insulating paint curing process is incomplete, the solids content calculated by traditional curing tests at a preset temperature will differ from the actual film formation rate. This can lead to significant differences in the actual film formation rate between different manufacturers with similar solids contents.

[0052] In order to solve the above problems, this implementation case calculates the area ratio of the deviated curve segment k = s1 / s×100% to obtain a more accurate film-forming rate, and calculates the film-forming rate of the insulating paint to be tested C = solid content m×(1-area ratio k). The actual film-forming rate of the insulating paint is obtained by calculating the ratio of each component at different weightlessness temperatures. When multiple insulating paints have similar solid content, price and performance, insulating paints with high film-forming rates can be purchased first to optimize production costs.

[0053] This method measures the thermal gravimetric curves of insulating paint films during production and after curing. By calculating the proportions of each component at different weight loss temperatures, the actual film-forming rate of the insulating paint can be indirectly calculated, thereby optimizing production costs. Analyzing the relationship between the solids content and film-forming rate of insulating paint using thermal gravimetric curves provides a new testing method for calculating insulating paint film process quotas. This method is simple to operate and has strong applicability, making it widely applicable for calculating the film-forming rates of different types of insulating paints.

[0054] Examples, such as Figure 2-3 As shown:

[0055] S100, solid content test:

[0056] Obtain the solid content m of the insulating varnish to be tested. In this embodiment, polyesterimide insulating varnishes from manufacturers A and B are respectively tested under the same test conditions (108°C, 1h). The solid content results are shown below:

[0057] factory Solid content A 39.26％ B 38.19％

[0058] S200, thermogravimetric test:

[0059] In this example, the standard paint film of the actual production process (the paint film obtained by peeling and twisting the enameled wire produced in the actual production) and the paint film of the insulating paint of manufacturers A and B after curing were subjected to thermogravimetric analysis respectively, and three thermogravimetric curves were obtained. The results are as follows: Figure 3 As shown, it can be clearly seen that in temperature zone 1 when the temperature is less than 350°C, the cured paint films of manufacturers A and B have a clear inflection point, that is, the presence of the target inflection point causes the thermal gravimetric loss curves of the paint films of manufacturers A and B to deviate from the thermal gravimetric loss curve of the standard paint film in the actual production process, while the standard paint film in the actual production process has no obvious inflection point, that is, the curve maintains a horizontal trend. On the other hand, in temperature zones 2 and 3 when the temperature is greater than 350°C, the shapes and trends of the thermal gravimetric loss curves of the three are basically the same, which can be indicated that the insulating paints of manufacturers A and B are not fully cured during the curing stage (180°C, 1h), and some low molecular weight substances will volatilize during the production process. Therefore, the solid content in step S100 fails to more accurately represent the film formation rate of each insulating paint on the enameled wire.

[0060] S300, curve peak area calculation:

[0061] In this example, the peak area of ​​the thermal gravimetric curve (DTG curve) of the paint film is used to represent the actual content. Origin and other related software are used to calculate the area ratio of the paint films of manufacturers A and B after curing in temperature zone 1, that is, the ratio of low molecular weight substances that are not fully cured. The results are shown in the following table:

[0062] factory Area ratio of District 1 A 6.63％ B 13.15％

[0063] S400, film formation rate calculation

[0064] The above results show that in the actual production process, the low molecular weight substances in the insulating varnishes of manufacturers A and B in temperature zone 1 will volatilize. Therefore, the actual solid content of the insulating varnishes of manufacturers A and B, that is, the film forming rate represented by them, is:

[0065] Manufacturer A: 39.26% × (1-6.63%) = 37.35%

[0066] Manufacturer B: 38.19% × (1-13.15%) = 33.87%

[0067] S500, the above calculation results and analysis conclusions are as follows:

[0068] factory Solid content Film forming rate A 39.26％ 37.35％ B 38.19％ 33.87％

[0069] It can be seen that different manufacturers may have large differences in their actual film-forming rates when the solid content is similar. When the price and performance are similar, it is preferred to purchase insulating varnish from manufacturers with high film-forming rates.

[0070] As an alternative to this embodiment, the polyesterimide insulating paint in the embodiment can be changed to polyurethane insulating paint or polyamideimide insulating paint or polyester insulating paint or corona-resistant insulating paint, and the same test method can also be used to calculate the relationship between the solid content and film-forming rate of different types of insulating paints.

[0071] On the other hand, the present invention also discloses another implementation case: a test device for evaluating the film-forming rate of insulating paint, comprising a memory and a processor, wherein the processor calls a control program stored in the memory to execute a test method for evaluating the film-forming rate of insulating paint as described above.

[0072] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read and write information from / to the storage medium. In an alternative embodiment, the storage medium may be integrated into the processor. The processor and storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative embodiment, the processor and storage medium may reside in the user terminal as discrete components.

[0073] On the other hand, the present invention also discloses another implementation case: a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the processor executes the above-mentioned test method for evaluating the film-forming rate of insulating paint.

[0074] Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media can be any available medium that can be accessed by a computer. As an example and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium.

[0075] The above disclosure is only one or more preferred embodiments of the present invention, which is used to help understand the inventive concept of the technical solution, and does not limit the present invention in other forms. Technicians in the relevant field may make other equivalent or customary replacement solutions based on the features defined by the present invention, which still fall within the scope of the present invention.

Claims

1. A test method for evaluating the film forming rate of insulating paint, characterized in that The following steps are involved: Obtaining the solid content m of the insulating varnish to be tested; Perform thermogravimetric analysis on the standard paint film in the actual production process and the paint film to be tested after curing of the insulating paint to be tested to obtain a thermogravimetric curve; Determining whether a target inflection point exists in the thermal gravimetric loss curve of the paint film to be tested, causing a certain curve segment to deviate from the standard paint film thermal gravimetric loss curve, including: obtaining multiple inflection points of the thermal gravimetric loss curve of the paint film to be tested, and determining the curve trend of the curve segment where the multiple inflection points are located; when the curve trend of the curve segment where a certain inflection point is located is different from the curve trend of the standard paint film thermal gravimetric loss curve in the same temperature range, the inflection point is the target inflection point, causing the certain curve segment to deviate from the standard paint film thermal gravimetric loss curve; Obtaining the area ratio k=s1 / s×100% of the deviated curve segment, including: determining the temperature range of the deviated curve segment, obtaining the peak area s1 of the curve segment within the temperature range and the peak area s of the thermal gravimetric loss curve of the paint film to be tested within a preset temperature; Calculate the film-forming rate C of the insulating varnish to be tested = solid content m × (1 - area ratio k).

2. A test method for evaluating the film-forming rate of insulating paint according to claim 1, characterized in that: The step of obtaining the solid content m of the insulating varnish to be tested comprises: Take 1-2g of the insulating varnish to be tested and evenly distribute it in a container with a mass of m0. Measure the total mass m1 of the container and the insulating varnish to be tested before baking. Bake the container evenly covered with the insulating paint to be tested at 180°C for 1 hour, and measure the total mass m2 of the container and the insulating paint to be tested after baking; Calculate the solid content m=(m2-m0) / (m1-m0)×100%.

3. A test method for evaluating the film-forming rate of insulating paint according to claim 1, characterized in that: The standard paint film of the actual production process is a paint film that has been used in actual production and can meet actual production needs. The paint film to be tested after the insulating paint to be tested is a paint film formed by baking the insulating paint to be tested at 180°C for 1 hour. The thermal gravimetric curve is a thermogravimetric differential curve.

4. A test method for evaluating the film-forming rate of insulating paint according to claim 1, characterized in that: The inflection point is a concave-convex curve dividing point that changes the trend direction of the curve. The trend direction of the curve includes one of the following: an upward trend direction of the curve, a horizontal trend direction of the curve, and a downward trend direction of the curve.

5. A test method for evaluating the film-forming rate of insulating paint according to claim 1, characterized in that: The temperature interval of the curve segment for determining the deviation includes: The starting end and the tail end of the curve segment obtained from the deviation correspond to two temperature values ​​on the horizontal temperature axis respectively, and the temperature interval between the two temperature values ​​is determined as the temperature interval for calculating the area ratio.

6. A test method for evaluating the film-forming rate of insulating paint according to claim 1, characterized in that: In calculating the area ratio of the deviated curve segment, the peak area of ​​the thermal gravimetric loss curve of the paint film to be tested within the preset temperature is used to represent the solid content of the insulating paint to be tested, and the peak area of ​​the curve segment within the temperature range is used to represent the content of low molecular weight substances volatilized within the temperature range.

7. A testing device for evaluating the film-forming rate of insulating paint, comprising a memory and a processor, characterized in that: The processor executes the test method for evaluating the film-forming rate of insulating paint according to any one of claims 1 to 6 by calling the control program stored in the memory.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, which, when executed by a processor, causes the processor to execute a test method for evaluating the film-forming rate of insulating paint according to any one of claims 1 to 6.

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