Roughened-film production control method and system

Abstract

A roughened-film production control method and system. The method comprises: S1, adjusting a melting temperature such that same is within a range from 230℃ to 240℃, and adjusting the temperature of sheet casting such that same is within a range from 80℃ to 90℃; S2, measuring the light transmittance of a longitudinally stretched thin film; S3, determining whether the light transmittance of the thin film is within a preset range; S4, if the light transmittance of the thin film is within the preset range, keeping the current melting temperature and the temperature of the sheet casting unchanged; and S5, if the light transmittance of the thin film is not within the preset range, adjusting, on the basis of the magnitude of the light transmittance of the thin film, the melting temperature and the temperature of the sheet casting according to a preset step length, and returning back to step S2. By means of testing the light transmittance of a longitudinally stretched thin film online, temperatures are controlled in melting and sheet casting stages, thereby realizing continuous control over the surface roughness and porosity of a capacitor thin film. The technical problems of it being difficult to apply an existing roughened-film drawing process to various roughened-film materials, the efficiency being low, and materials being wasted are solved.

Description

A roughening film production control method and system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on October 9, 2023, with application number 202311298351.0 and invention name “A roughening membrane production control method and system”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of roughening film production technology, and in particular to a roughening film production control method and system. Background Art

[0003] Biaxially oriented polypropylene roughened film is the primary solid dielectric material for high-voltage oil-immersed capacitors and is used in large quantities. Porosity and surface roughness are crucial parameters for roughened films. If the porosity is too low and the surface roughening is insufficient, the capacitor impregnant cannot penetrate between the film layers, resulting in insufficient withstand voltage and aging.

[0004] The degree of surface roughening of the roughened film is related to parameters such as the molecular weight distribution and isotactic index of the polypropylene raw material. It is usually difficult to ensure that the molecular weight distribution and isotactic index of polymer materials remain unchanged during the polymerization process. In particular, there will be significant differences in the molecular weight distribution and isotactic index of materials produced by different manufacturers. In the existing roughened film drawing process, it is mainly based on previous processing experience. After the film is drawn, a test is performed. If the surface roughening can meet the requirements, the production is continued according to the existing process. Otherwise, the temperature during the film drawing process is adjusted until the surface roughening of the film meets the requirements. For the production of roughened films with single-source materials, the temperature can be adjusted according to experience to meet the surface roughening requirements of the film. However, when the roughened film material is replaced, the original roughened film drawing process experience will no longer apply. It is necessary to go through a long process of testing after the film is drawn. If the surface roughening can meet the requirements, the production is continued according to the existing process. Otherwise, the temperature during the film drawing process is adjusted until the surface roughening of the film meets the requirements. This is not only inefficient but also wastes materials. Therefore, how to design a roughening membrane production process that is suitable for a variety of roughening membrane materials to improve roughening membrane production efficiency and reduce material waste is a technical problem that needs to be solved urgently by those skilled in the art.

[0005] Summary of the Invention

[0006] The present invention provides a roughening film production control method and system for solving the technical problems that the existing roughening film drawing process is difficult to apply to a variety of roughening film materials, is inefficient and wastes materials.

[0007] In view of this, a first aspect of the present invention provides a roughening film production control method, comprising:

[0008] S1. Adjust the melt temperature to 230-240°C and the cast sheet temperature to 80-90°C;

[0009] S2. measuring the light transmittance of the longitudinally stretched film;

[0010] S3, judging whether the light transmittance of the film is within a preset range;

[0011] S4. If the film transmittance is within the preset range, the current melting temperature and cast sheet temperature are kept unchanged;

[0012] S5. If the light transmittance of the film is not within the preset range, the melting temperature and the temperature of the cast sheet are adjusted in a preset step size according to the light transmittance of the film, and the process returns to step S2.

[0013] Optionally, the preset range is 40-60%.

[0014] Optionally, step S5 includes:

[0015] Determine whether the film transmittance is less than the lower limit of the preset range. If so, increase the melting temperature and the cast sheet temperature according to the preset step size and return to step S2. Otherwise, reduce the melting temperature and the cast sheet temperature according to the preset step size and return to step S2.

[0016] Optionally, step S5 includes:

[0017] Determine whether the film transmittance is greater than the upper limit of the preset range. If so, lower the melting temperature and the cast sheet temperature according to the preset step size and return to step S2. Otherwise, increase the melting temperature and the cast sheet temperature according to the preset step size and return to step S2.

[0018] Optionally, step S2 includes:

[0019] S2-1, start the longitudinal stretching program;

[0020] S2-2. Measure the luminous flux of the film using a luminous flux measuring device, the luminous flux measuring device comprising a light source, an upper condenser, a lower condenser, an upper modulator, a lower modulator, an upper objective lens, a lower objective lens, an upper integrating sphere, a lower integrating sphere, an upper photometer, and a lower photometer, wherein the upper integrating sphere is located above the film and is arranged adjacent to the film, and the upper objective lens, the upper modulator, the upper condenser, the light source, the lower condenser, the lower modulator, the lower objective lens, and the lower integrating sphere are arranged sequentially from top to bottom below the film, the upper photometer is used to output the luminous flux value of the upper integrating sphere, and the lower photometer is used to output the luminous flux value of the lower integrating sphere;

[0021] S2-3. Calculate the light transmittance of the film based on the luminous flux value of the upper integrating sphere and the luminous flux value of the lower integrating sphere.

[0022] Optionally, the preset step size is 1 to 5k.

[0023] A second aspect of the present invention provides a roughening film production control system, comprising:

[0024] Temperature initialization module, used to adjust the melt temperature to 230-240°C and the cast sheet temperature to 80-90°C;

[0025] Film transmittance measurement module, used to measure the transmittance of longitudinally stretched films;

[0026] A judgment module, used to judge whether the light transmittance of the film is within a preset range;

[0027] The first control module is used to keep the current melting temperature and cast sheet temperature unchanged if the film transmittance is within a preset range;

[0028] The second control module is used to adjust the melting temperature and the casting sheet temperature according to the preset step size based on the film transmittance if the film transmittance is not within the preset range, and return to execute the film transmittance measurement module.

[0029] Optionally, the second control module is specifically configured to:

[0030] Determine whether the film transmittance is less than the preset range lower limit. If so, increase the melting temperature and the cast sheet temperature by the preset step size and return to the film transmittance measurement module. Otherwise, decrease the melting temperature and the cast sheet temperature by the preset step size and return to the film transmittance measurement module.

[0031] Or, determine whether the film transmittance is greater than the upper limit of the preset range. If so, lower the melting temperature and the cast sheet temperature according to the preset step size, and return to execute the film transmittance measurement module; otherwise, increase the melting temperature and the cast sheet temperature according to the preset step size, and return to execute the film transmittance measurement module.

[0032] Optionally, the thin film transmittance measurement module includes:

[0033] A longitudinal stretching starter module is used to start the longitudinal stretching program;

[0034] A luminous flux measurement submodule is used to measure the luminous flux of the film through a luminous flux measurement device, the luminous flux measurement device including a light source, an upper condenser, a lower condenser, an upper modulator, a lower modulator, an upper objective lens, a lower objective lens, an upper integrating sphere, a lower integrating sphere, an upper photometer, and a lower photometer. The upper integrating sphere is located above the film and is arranged adjacent to the film. The upper objective lens, the upper modulator, the upper condenser, the light source, the lower condenser, the lower modulator, the lower objective lens, and the lower integrating sphere are arranged in order from top to bottom below the film. The upper photometer is used to output the luminous flux value of the upper integrating sphere, and the lower photometer is used to output the luminous flux value of the lower integrating sphere.

[0035] The transmittance calculation submodule is used to calculate the light transmittance of the film according to the luminous flux value of the upper integrating sphere and the luminous flux value of the lower integrating sphere.

[0036] From the above technical solutions, it can be seen that the roughening film production control method provided by the present invention has the following advantages:

[0037] The roughening film production control method provided by the present invention realizes continuous control of the surface roughness and porosity of the capacitor film by online testing of the transmittance of the longitudinally stretched film and controlling the temperature during the melting and casting stages, thereby reducing the material loss caused by the poor timeliness of offline control and solving the technical problems that the existing roughening film drawing process is difficult to apply to a variety of roughening film materials, is inefficient and wastes materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying any creative work.

[0039] FIG1 is a schematic flow diagram of a roughening film production control method provided in the present invention;

[0040] FIG2 is a schematic flow chart of a specific embodiment of a roughening film production control method provided in the present invention;

[0041] FIG3 is a schematic flow chart of another specific embodiment of a roughening film production control method provided in the present invention;

[0042] FIG4 is a schematic diagram of the structure and installation position of the luminous flux measurement device provided in the present invention;

[0043] FIG5 is a schematic structural diagram of a roughening film production control system provided in the present invention. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0045] For ease of understanding, please refer to FIG1 . The present invention provides an embodiment of a roughening film production control method, comprising:

[0046] Step 101: Adjust the melting temperature to 230-240°C and the casting temperature to 80-90°C.

[0047] It should be noted that the β-crystal content and grain (spherulite) morphology of the tape-cast sheet are closely related to the micropores and cavitation of the film body. The formation of the skin-core layered structure and the transverse crystal grains in the skin layer are important reasons for the roughening of the film surface. However, based on the electrical performance requirements of the roughened film, it is not allowed to change the grain shape and improve the surface roughening morphology by adding β-nucleating agents. The crystallinity, homogeneous polymorphism, crystalline morphology, crystal structure, skin-core structure, etc. of the tape-cast sheet are all formed in the transition from melting to supercooling. Controlling surface roughening requires effective control of these structural factors. The film stretching process is divided into melting, tape-casting, longitudinal stretching, transverse stretching and other processes. The most important process affecting the β-crystal parameters is the temperature of the two processes of melting and tape-casting. In the embodiment of the present invention, the melting temperature is first adjusted to 230-240°C, and the temperature of the tape-cast sheet is adjusted to 80-90°C.

[0048] Step 102: Measure the light transmittance of the longitudinally stretched film.

[0049] It should be noted that the stretching and coarsening of the film mainly depends on the internal β-crystal content and distribution. The regulation or production of β-crystals is only produced during the melting to cooling process. Increasing the temperature of the casting sheet (the thicker film placed on the cold drum after melting is called a casting sheet) generally produces more β-crystals. In other words, the whole process is determined by the two processes of melting and cooling, and cannot be adjusted in the later stage. The main purpose of transverse stretching is to convert β-crystals into α-crystals. The transmittance range is too small and the control is difficult. In the longitudinal stretching stage, there are still a large number of β-crystals in the film, and the transmittance varies over a large range and is easy to adjust and control. Therefore, in the embodiment of the present invention, after starting the longitudinal stretching program to longitudinally stretch the film, the film transmittance of the longitudinally stretched film is measured.

[0050] Specifically, the film transmittance can be measured by a luminous flux measuring device. As shown in Figure 4, the luminous flux measuring device includes a light source, an upper condenser, a lower condenser, an upper modulator, a lower modulator, an upper objective lens, a lower objective lens, an upper integrating sphere, a lower integrating sphere, an upper photometer, and a lower photometer. The upper integrating sphere is located above the film and is arranged in close proximity to the film. The upper objective lens, upper modulator, upper condenser, light source, lower condenser, lower modulator, lower objective lens, and lower integrating sphere are arranged below the film in order from top to bottom. The upper photometer is used to output the luminous flux value of the upper integrating sphere, and the lower photometer is used to output the luminous flux value of the lower integrating sphere. The film transmittance is calculated based on the luminous flux values ​​of the upper and lower integrating spheres. The light source is a halogen tungsten lamp. The luminous flux value of the upper integrating sphere output by the upper photometer is recorded as T1, and the luminous flux value of the lower integrating sphere output by the lower photometer is recorded as T2. The film transmittance is T1 / T2. Wherein, T1=T2=(P1×t1-P0) / t, P1 is the luminous flux of the modulator (T1 corresponds to the upper modulator, T2 corresponds to the lower modulator) under light-transmitting conditions, P0 is the luminous flux of the modulator (T1 corresponds to the upper modulator, T2 corresponds to the lower modulator) under opaque conditions, t is the period of the modulator (T1 corresponds to the upper modulator, T2 corresponds to the lower modulator), and t1 is the time it takes for light to pass through the modulator (T1 corresponds to the upper modulator, T2 corresponds to the lower modulator).

[0051] Step 103: Determine whether the light transmittance of the film is within a preset range.

[0052] It should be noted that in the embodiment of the present invention, after completing the measurement of the transmittance of the longitudinally stretched film, it is necessary to determine whether the transmittance of the film is within the preset range. Specifically, the preset range is 40-60%. The transmittance is related to the subsequent degree of surface roughness. The higher the transmittance, the smoother the surface in the later stage, and vice versa. Capacitors generally use a multi-layer structure. If it is too smooth, it will not be conducive to the oil entering the two layers of dielectrics. If it is too rough, there will be too many weaknesses, which is not conducive to voltage resistance. The average thickness is the same and the roughness is high. There may be individual locations where the actual thickness is thinner and easy to break down. However, if it is too smooth, there will be no grooves between the two layers of film and it cannot be entered. There are gaps inside, which are easy to break down. Within the range of 40-60%, the standard requirement of 9%±3% can be met.

[0053] Step 104: If the light transmittance of the film is within the preset range, the current melting temperature and the temperature of the cast sheet are kept unchanged.

[0054] Step 105 : If the light transmittance of the film is not within the preset range, the melting temperature and the temperature of the tape casting sheet are adjusted in a preset step size according to the light transmittance of the film, and the process returns to step 102 .

[0055] It should be noted that when the film transmittance is within the preset range, it means that the current melting temperature and the temperature of the cast sheet meet the requirements, and the current melting temperature and the temperature of the cast sheet can be kept unchanged. When the film transmittance is not within the preset range, the melting temperature and the temperature of the cast sheet are adjusted according to the preset step size according to the size of the film transmittance, and the film transmittance is remeasured in step 102, and the film transmittance is adjusted continuously until the film transmittance is within the preset range. Among them, considering that the temperature difference adjustment is too high, it is easy to over-adjust, which will prolong the adjustment process. At the same time, the cold drum and the melt are both very large devices with very large thermal inertia. It is impossible to adjust a large temperature difference in a short time. Therefore, in the embodiment of the present invention, the preset step size for adjusting the melting temperature and the cast sheet temperature is between 1 and 5k.

[0056] In one embodiment, as shown in FIG2 , when the light transmittance of the film is not within the preset range, it is necessary to determine whether the light transmittance of the film is less than the lower limit of the preset range. If so, the melting temperature and the temperature of the tape casting sheet are increased according to the preset step size, and the process returns to step 102 . Otherwise, the melting temperature and the temperature of the tape casting sheet are lowered according to the preset step size, and the process returns to step 102 .

[0057] In one embodiment, as shown in FIG3 , when the light transmittance of the film is not within the preset range, it is necessary to determine whether the light transmittance of the film is greater than the upper limit of the preset range. If so, the melting temperature and the temperature of the tape casting sheet are lowered according to the preset step size, and the process returns to step 102 . Otherwise, the melting temperature and the temperature of the tape casting sheet are increased according to the preset step size, and the process returns to step 102 .

[0058] The roughening film production control method provided by the present invention realizes continuous control of the surface roughness and porosity of the capacitor film by online testing of the transmittance of the longitudinally stretched film and controlling the temperature during the melting and casting stages, thereby reducing the material loss caused by the poor timeliness of offline control and solving the technical problems that the existing roughening film drawing process is difficult to apply to a variety of roughening film materials, is inefficient and wastes materials.

[0059] For ease of understanding, please refer to FIG5 . The present invention provides an embodiment of a roughening film production control system, including:

[0060] Temperature initialization module, used to adjust the melt temperature to 230-240°C and the cast sheet temperature to 80-90°C;

[0061] Film transmittance measurement module, used to measure the transmittance of longitudinally stretched films;

[0062] A judgment module, used to judge whether the light transmittance of the film is within a preset range;

[0063] The first control module is used to keep the current melting temperature and cast sheet temperature unchanged if the film transmittance is within a preset range;

[0064] The second control module is used to adjust the melting temperature and the casting sheet temperature according to the preset step size based on the film transmittance if the film transmittance is not within the preset range, and return to execute the film transmittance measurement module.

[0065] The preset range is 40 to 60%.

[0066] The second control module is specifically configured to:

[0067] Determine whether the film transmittance is less than the preset range lower limit. If so, increase the melting temperature and the cast sheet temperature by the preset step size and return to the film transmittance measurement module. Otherwise, decrease the melting temperature and the cast sheet temperature by the preset step size and return to the film transmittance measurement module.

[0068] Or, determine whether the film transmittance is greater than the upper limit of the preset range. If so, lower the melting temperature and the cast sheet temperature according to the preset step size, and return to execute the film transmittance measurement module; otherwise, increase the melting temperature and the cast sheet temperature according to the preset step size, and return to execute the film transmittance measurement module.

[0069] Thin film transmittance measurement module includes:

[0070] A longitudinal stretching starter module is used to start the longitudinal stretching program;

[0071] A luminous flux measurement submodule is used to measure the luminous flux of the film through a luminous flux measurement device, the luminous flux measurement device including a light source, an upper condenser, a lower condenser, an upper modulator, a lower modulator, an upper objective lens, a lower objective lens, an upper integrating sphere, a lower integrating sphere, an upper photometer, and a lower photometer. The upper integrating sphere is located above the film and is arranged adjacent to the film. The upper objective lens, the upper modulator, the upper condenser, the light source, the lower condenser, the lower modulator, the lower objective lens, and the lower integrating sphere are arranged in order from top to bottom below the film. The upper photometer is used to output the luminous flux value of the upper integrating sphere, and the lower photometer is used to output the luminous flux value of the lower integrating sphere.

[0072] The transmittance calculation submodule is used to calculate the light transmittance of the film according to the luminous flux value of the upper integrating sphere and the luminous flux value of the lower integrating sphere.

[0073] The preset step size is 1 to 5k.

[0074] The roughening membrane production control system provided in the present invention is used to execute the roughening membrane production control method provided in the present invention. Its principles and technical effects are the same as those of the roughening membrane production control method provided in the present invention, and will not be repeated here.

[0075] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A roughening film production control method, characterized in that: include: S1, adjusting the melting temperature to 230-240°C, and adjusting the casting temperature to 80-90°C; S2, measuring the light transmittance of the longitudinally stretched film; S3, judging whether the light transmittance of the film is within a preset range; S4. If the light transmittance of the film is within the preset range, the current melting temperature and the temperature of the cast sheet are kept unchanged; S5. If the light transmittance of the film is not within the preset range, the melting temperature and the temperature of the cast sheet are adjusted according to the preset step size based on the light transmittance of the film, and the process returns to step S2.

2. The roughening film production control method according to claim 1, characterized in that: The preset range is 40~60%.

3. The roughening film production control method according to claim 1, characterized in that: Step S5 includes: Determine whether the film transmittance is less than the lower limit of the preset range. If so, increase the melting temperature and the temperature of the cast sheet according to the preset step size and return to step S2. Otherwise, reduce the melting temperature and the temperature of the cast sheet according to the preset step size and return to step S2.

4. The roughening film production control method according to claim 1, characterized in that: Step S5 includes: Determine whether the film transmittance is greater than the upper limit of the preset range. If so, lower the melting temperature and the temperature of the cast sheet according to the preset step size and return to step S2. Otherwise, increase the melting temperature and the temperature of the cast sheet according to the preset step size and return to step S2.

5. The roughening film production control method according to claim 1, characterized in that: Step S2 includes: S2-1, start the longitudinal stretching program; S2-2. Measure the luminous flux of the film by a luminous flux measuring device, the luminous flux measuring device comprising a light source, an upper condenser, a lower condenser, an upper modulator, a lower modulator, an upper objective lens, a lower objective lens, an upper integrating sphere, a lower integrating sphere, an upper photometer and a lower photometer, the upper integrating sphere is located above the film and is arranged close to the film, the upper objective lens, the upper modulator, the upper condenser, the light source, the lower condenser, the lower modulator, the lower objective lens and the lower integrating sphere are arranged in sequence from top to bottom below the film, the upper photometer is used to output the luminous flux value of the upper integrating sphere, and the lower photometer is used to output the luminous flux value of the lower integrating sphere; S2-3. Calculate the light transmittance of the film according to the luminous flux value of the upper integrating sphere and the luminous flux value of the lower integrating sphere.

6. The roughening film production control method according to claim 5, characterized in that: The preset step size is 1 to 5k.

7. A roughening film production control system, characterized in that: include: Temperature initialization module, used to adjust the melting temperature to 230-240°C and the casting temperature to 80-90°C; Film transmittance measurement module, used to measure the transmittance of longitudinally stretched films; A judgment module, used to judge whether the light transmittance of the film is within a preset range; The first control module is used to keep the current melting temperature and the temperature of the cast sheet unchanged if the light transmittance of the film is within a preset range; The second control module is used to adjust the melting temperature and the temperature of the cast sheet according to the preset step size according to the size of the film transmittance if the film transmittance is not within the preset range, and return to execute the film transmittance measurement module.

8. The roughening film production control system according to claim 7, characterized in that: The preset range is 40~60%.

9. The roughening film production control system according to claim 7, characterized in that: The second control module is specifically used for: Determine whether the film transmittance is less than the preset range lower limit. If so, increase the melting temperature and the cast sheet temperature according to the preset step length, and return to the film transmittance measurement module; otherwise, reduce the melting temperature and the cast sheet temperature according to the preset step length, and return to the film transmittance measurement module; Or, determine whether the film transmittance is greater than the upper limit of the preset range. If so, lower the melting temperature and the cast sheet temperature according to the preset step size, and return to the film transmittance measurement module. Otherwise, increase the melting temperature and the cast sheet temperature according to the preset step size, and return to the film transmittance measurement module.

10. The roughening film production control system according to claim 7, characterized in that: The film transmittance measurement module includes: A longitudinal stretching initiator module, used to initiate a longitudinal stretching program; The luminous flux measurement submodule is used to measure the luminous flux of the film through a luminous flux measurement device, the luminous flux measurement device includes a light source, an upper condenser, a lower condenser, an upper modulator, a lower modulator, an upper objective lens, a lower objective lens, an upper integrating sphere, a lower integrating sphere, an upper photometer and a lower photometer, the upper integrating sphere is located at The upper objective lens, the upper modulator, the upper condenser, the light source, the lower condenser, the lower modulator, the lower objective lens and the lower integrating sphere are arranged below the film from top to bottom, the upper photometer is used to output the luminous flux value of the upper integrating sphere, and the lower photometer is used to output the luminous flux value of the lower integrating sphere; The transmittance calculation submodule is used to calculate the light transmittance of the film according to the luminous flux value of the upper integrating sphere and the luminous flux value of the lower integrating sphere.

Images