Slit coating head, coating machine, and method of operating the slit coating head

Abstract

The present invention belongs to the technical field of general methods for coating fluids on surfaces, and specifically relates to a coating head with a slit-type outlet, and in particular to a slit coating head, a coating machine, and a working method of the slit coating head. The slit coating head comprises: an upper coating die head and a lower coating die head; a coating slit is formed between the upper coating die head and the lower coating die head; a main flow channel and a plurality of secondary flow channels are provided in the upper coating die head; the main flow channel is connected to each secondary flow channel; and an adjustment mechanism is provided in each secondary flow channel, and the adjustment mechanism is configured to detect the flow rate of the slurry in the corresponding secondary flow channel to adjust the flow rate of the slurry in the secondary flow channel. The dynamic adjustment method of the adjustment mechanism can effectively avoid pressure fluctuations of the slurry flow while adjusting the slurry flow rate in the secondary flow channel, thereby ensuring the consistency of the coating slit on the film.

Description

Technical Field

[0001] The present invention belongs to the technical field of general methods for coating fluids on surfaces, and specifically relates to a coating head with a slit-type outlet, and more particularly to a slit coating head, a coating machine and a working method of the slit coating head. Background Art

[0002] When coating the electronic protective film, slit coating is mainly used. In slit coating, since the feed port in the coating die is located in the center of the die, during the cavity pressure equalization process, when the slurry flows from the feed port to the two ends of the cavity, the flow path is too long and the pressure drop is large, resulting in a large pressure difference between the center of the cavity and the two ends of the cavity, and the cavity pressure gradually decreases from the center to the two ends. Different cavity pressures result in different coating thicknesses and poor coating uniformity.

[0003] In this regard, the relevant technology usually adopts multiple diversion channels to evenly distribute the slurry. By setting a baffle in each diversion channel to change the effective cross-sectional area of ​​the corresponding diversion channel, the flow pressure of the flow is changed, so that the slurry flows to the channel with low flow pressure, and the slurry distribution is optimized through pressure balance.

[0004] However, since the baffle achieves pressure regulation by adjusting the effective cross-sectional area of ​​the flow channel, when the effective cross-sectional area of ​​the corresponding flow channel decreases, it will cause an instantaneous impact, which will lead to a surge in pressure in the flow channel, thereby increasing the shear rate of the slurry, causing the slurry viscosity to drop instantaneously, which in turn further amplifies the flow rate and pressure fluctuation amplitude.

[0005] Based on the above problems, it is necessary to design a slit coating head, a coating machine and a working method of the slit coating head.

[0006] It should be noted that the above information disclosed in this background technology section is only used to understand the background technology of the present application concept, and therefore, the above description is not considered to constitute information of the prior art. Summary of the Invention

[0007] The embodiments of the present disclosure at least provide a slit coating head, a coating machine, and a working method of the slit coating head.

[0008] In a first aspect, an embodiment of the present disclosure provides a slot coating head, comprising: an upper coating die head and a lower coating die head;

[0009] A coating slit is formed between the upper coating die and the lower coating die; wherein

[0010] The upper coating die head is provided with a main flow channel and a plurality of secondary flow channels;

[0011] The main flow channel is connected to each secondary flow channel; and

[0012] Each of the slave flow channels is provided with an adjusting mechanism, and the adjusting mechanism is configured to detect the flow rate of the slurry in the corresponding slave flow channel to adjust the flow rate of the slurry in the slave flow channel.

[0013] In an optional embodiment, the regulating mechanism includes: a flow-blocking regulating column and a flow sensor;

[0014] The flow sensor is arranged at the discharge port of the flow channel; and

[0015] The flow-blocking adjustment column is slidably arranged in the flow channel; wherein

[0016] The flow resistance adjustment column is configured to slide according to the flow data obtained by the flow sensor, thereby adjusting the effective cross-sectional area of ​​the flow channel feed port.

[0017] In an optional embodiment, the bottom end surface of the flow resistance adjustment column is inclined to guide the slurry entering from the flow channel feed port to smoothly transition from horizontal flow to vertical flow; and

[0018] A buffer flow channel is further provided inside the flow-blocking adjustment column. The first opening of the buffer flow channel is located on the arc-shaped side wall of the adjustment column, and the second opening is located on the inclined bottom wall of the adjustment column.

[0019] In an optional embodiment, the regulating mechanism further includes: a control module;

[0020] The control module is electrically connected to the flow sensor and the driving element of the resistance adjustment column respectively; wherein

[0021] The control module is configured to obtain flow data detected by the flow sensor, and control the start and stop of the driving member of the choke adjustment column according to the flow data, thereby adjusting the position of the choke adjustment column in the flow channel.

[0022] In an optional embodiment, when the choke regulating column moves downward from the starting position to reduce the cross-sectional area of ​​the flow channel feed port, the second opening of the buffer flow channel is configured to absorb pressure fluctuations generated when the choke regulating column moves.

[0023] In an optional embodiment, when the flow resistance adjustment column moves to the slave flow channel feed port and is closed, the first opening of the buffer flow channel is connected to the slave flow channel feed port, and the buffer flow channel is configured to provide a flow path for the slurry.

[0024] In a second aspect, an embodiment of the present disclosure further provides a coating machine, comprising: an unwinding device, a winding device, and a slit coating head;

[0025] The slit coating head is suitable for using the above-mentioned slit coating head;

[0026] The slit coating head is arranged between the unwinding device and the winding device;

[0027] The unwinding device is configured to unwind a film, and the slit coating head coats the unwinding film; and

[0028] The winding device is configured to wind up the coated film.

[0029] In a third aspect, the present disclosure also provides a method for operating a slit coating head, comprising: controlling the flow rate of the slurry in the flow channel by an adjusting mechanism, that is,

[0030] When the flow rate of the slurry in the corresponding slave flow channel in the slit coating head exceeds a preset flow rate, the flow resistance adjustment column in the slave flow channel is moved downward to reduce the effective cross-sectional area of ​​the slave flow channel feed port, thereby increasing the resistance of the slurry flowing into the slave flow channel; and

[0031] When the flow rate still exceeds the preset flow rate after the effective cross-sectional area of ​​the slave flow channel feed port is adjusted to the minimum threshold, the flow resistance adjustment column continues to be moved downward so that the first opening of the flow resistance adjustment column is connected to the slave flow channel feed port, so that the slurry flows from the buffer channel into the slave flow channel.

[0032] The beneficial effects of the present invention are as follows: the slit coating head comprises: an upper coating die head and a lower coating die head; a coating slit is formed between the upper coating die head and the lower coating die head; wherein the upper coating die head is provided with a main channel and a plurality of secondary channels; the main channel is connected to each secondary channel; and each secondary channel is provided with an adjustment mechanism, wherein the adjustment mechanism is configured to detect the flow rate of the slurry in the corresponding secondary channel to adjust the flow rate of the slurry in the secondary channel. The dynamic adjustment method of the adjustment mechanism effectively avoids pressure fluctuations of the slurry flow while adjusting the flow rate of the secondary channel slurry, thereby ensuring the consistency of the coating slit on the film.

[0033] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description and the drawings.

[0034] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited herein and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic structural diagram of a slit coating head provided in an embodiment of the present disclosure;

[0037] Figure 2 A schematic diagram of a partial structure of a slit coating head provided in an embodiment of the present disclosure;

[0038] Figure 3 A schematic cross-sectional view of a slit coating head according to an embodiment of the present disclosure;

[0039] Figure 4 A schematic structural diagram of a coating machine provided in an embodiment of the present disclosure;

[0040] Figure 5 A schematic diagram of a first state of a flow-blocking adjustment column provided in an embodiment of the present disclosure;

[0041] Figure 6 A schematic diagram of a second state of the flow resistance adjustment column provided in an embodiment of the present disclosure;

[0042] Figure 7 A schematic diagram of a third state of the flow resistance adjustment column provided in an embodiment of the present disclosure;

[0043] Figure 8 A schematic diagram of the internal structure of the flow-blocking adjustment column provided in an embodiment of the present disclosure.

[0044] In the picture:

[0045] 1 slit coating head, 11 upper coating die head, 111 main flow channel, 112 secondary flow channel, 12 regulating mechanism, 120 driving member, 121 flow resistance regulating column, 122 flow sensor, 123 buffer flow channel, 124 first opening, 125 second opening, 13 feed port, 15 lower coating die head, 151 accommodating chamber, 16 coating slit;

[0046] 2. Unwinding device;

[0047] 3. Winding device;

[0048] 4 films. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] As used herein, the phrases "in one embodiment," "according to one embodiment," "in some embodiments," and the like generally refer to the fact that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure. Thus, a particular feature, structure, or characteristic may be included in more than one embodiment of the present disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms "example," "exemplary," and the like are used to "serve as an example, instance, or illustration." Any implementation, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations, aspects, or designs. Instead, the use of the terms "example," "exemplary," and the like is intended to present concepts in a concrete manner.

[0051] When coating the electronic protective film, the main slurry is nano-silica epoxy resin-based slurry, which is coated by slit coating. The inventors found that in slit coating, the traditional flow block reduces the cross-sectional area of ​​the flow channel, which will cause instantaneous impact. For nano-silica epoxy resin-based slurry with a large density difference, the shear rate of the slurry will increase due to the instantaneous pressure surge, which will cause the viscosity of the slurry to drop instantaneously, further amplifying the flow rate and pressure fluctuation amplitude, resulting in repeated adjustments.

[0052] The defects in the above solutions are the results obtained by the inventors after practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed by the present disclosure in this article should be the contributions made by the inventors to the present disclosure during the disclosure process.

[0053] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0054] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features therein may be combined with each other.

[0055] like Figure 1As shown, at least one disclosed embodiment provides a slit coating head, comprising: an upper coating die 11 and a lower coating die 15; a coating slit 16 is formed between the upper coating die 11 and the lower coating die 15; wherein a main channel 111 and a plurality of secondary channels 112 are provided in the upper coating die 11; the main channel 111 is connected to each secondary channel 112; and an adjusting mechanism 12 is provided in each secondary channel 112, and the adjusting mechanism 12 is configured to detect the flow rate of the slurry in the corresponding secondary channel 112 to adjust the flow rate of the slurry in the secondary channel 112.

[0056] In this embodiment, by setting up multiple slave channels 112, the slurry in the main channel 111 can flow into the accommodating cavity 151 more evenly, and the adjusting mechanism 12 set in the corresponding slave channel 112 is used to adjust the size of the feed port of the slave channel, thereby changing the slurry flow resistance in the slave channel 112. Specifically, if the slurry flow rate in a certain slave channel 112 is greater than the preset flow rate, at this time, the driving member 120 is required to drive the flow resistance adjusting column 121 to move to reduce the cross-sectional area of ​​the feed port of the slave channel 112, so that the resistance of the slurry flowing into this slave channel 112 increases, thereby reducing the flow rate of the slurry flowing into the slave channel 112.

[0057] Specifically, the driving member 120 includes but is not limited to using a micro cylinder or a micro motor in conjunction with a screw rod to drive the flow control adjustment column 121 to move.

[0058] like Figure 2 and Figure 8 As shown, in an optional embodiment, the regulating mechanism 12 includes: a flow resistance regulating column 121 and a flow sensor 122; the flow sensor 122 is arranged at the discharge port of the slave channel 112; and the flow resistance regulating column 121 is slidably arranged in the slave channel 112; wherein the flow resistance regulating column 121 is configured to slide according to the flow data obtained by the flow sensor 122, thereby adjusting the effective cross-sectional area of ​​the feed port of the slave channel 112.

[0059] Specific as Figure 5 、 Figure 6 and Figure 7 As shown, the lower end surface of the flow-blocking regulating column 121 is set as an inclined surface. Under normal flow conditions, the slurry will Figure 5 In the direction F shown, the slurry entering from the flow channel feed port smoothly transitions from horizontal flow to vertical flow under the guidance of the lower end surface of the flow resistance adjustment column 121 to avoid flow fluctuations of the slurry. At the same time, when it is necessary to reduce the effective cross-sectional area of ​​the flow channel feed port, as shown in FIG. Figure 6As shown, the slurry is still flowing in the direction F in the figure, but the buffer channel 123 opened in the flow resistance adjustment column 121 can absorb the pressure fluctuations generated during its adjustment. Specifically, during coating, the slurry is filled in the slave channel. When the pressure in the slave channel increases, the slurry will preferentially flow to the position with low pressure. Since the width of the flow channel opening of the buffer channel 123 is greater than the width of the coating slit, the flow resistance of the buffer channel is lower. When the pressure suddenly increases, the slurry will preferentially flow into the buffer channel with lower pressure due to the characteristic of "flowing from high pressure to low pressure", thereby alleviating the slave channel pressure. In addition, since there is gas in the buffer channel, and the gas is compressible, the gas in the buffer channel is compressed by the inflowing slurry, forming a spring-like effect to store pressure energy and alleviate the pressure peak in the channel. At the same time, since the fixed end of the drive member is fixedly set on the die head, the flow resistance adjustment column 121 itself will not move, thereby ensuring that the slurry in the slave channel 112 still maintains as stable a flow as possible during the adjustment process.

[0060] At the same time, in the related art, when the flow rate in a certain secondary flow channel 112 is always large, the flow resistance adjustment column 121 may be over-adjusted, causing the secondary flow channel 112 to be closed, thereby causing coating defects.

[0061] Based on the above problem, if the flow rate in a certain flow channel is always large, that is, after the flow control column 121 moves downward to the limit position, it is still found that the flow rate here is greater than the preset flow rate, the flow control column 121 is further moved downward, such as Figure 7 As shown, the first opening 124 of the buffer channel 123 is connected to the feed port of the slave channel, so that the slurry in the slave channel flows along the F2 direction. Since the buffer channel 123 is provided with multiple bends, the flow resistance is further increased while ensuring that there is always slurry flow in the channel, avoiding coating gaps caused by channel closure.

[0062] Specifically, when the flow-blocking adjustment column 121 moves downward from the starting position to reduce the cross-sectional area of ​​the slave flow channel feed port, the second opening of the buffer flow channel is configured to absorb pressure fluctuations generated by the movement of the flow-blocking adjustment column 121. When the flow-blocking adjustment column moves to the slave flow channel feed port and is closed, the first opening of the buffer flow channel is connected to the slave flow channel feed port, and the buffer flow channel is now configured to provide a flow path for the slurry.

[0063] In this embodiment, the pressure in the slave flow channel 112 is reflected by detecting the flow rate of the slurry. When the flow rates in each slave flow channel 112 are the same, it means that the pressure in each slave flow channel 112 is the same, and the amount of slurry entering the accommodating cavity 151 from each slave flow channel 112 is the same, ensuring that the pressure of the slurry flowing out of the accommodating cavity 151 through the coating slit 16 for coating is the same at each position, thereby ensuring coating consistency.

[0064] like Figure 1 As shown, in an optional embodiment, a feed port 13 is provided on the upper coating die 11, and the feed port 13 is connected to the main channel 111, and the slurry is filled into the main channel 111 through the feed port 13; a receiving cavity 151 is formed between the upper coating die 11 and the lower coating die 15; the receiving cavity 151 is connected to the coating slit 16, and the slurry in the receiving cavity 151 flows out from the coating slit 16 for coating.

[0065] like Figure 4 As shown, at least one other disclosed embodiment further provides a coating machine, comprising an unwinding device 2, a winding device 3 and a slit coating head 1; the slit coating head 1 is suitable for adopting the above-mentioned slit coating head 1; the slit coating head 1 is arranged between the unwinding device 2 and the winding device 3; the unwinding device 2 is configured to unwind a film 4, and the slit coating head 1 coats the unwound film 4; and the winding device 3 is configured to rewind the coated film 4.

[0066] In an optional embodiment, the unwinding device 2 includes but is not limited to being implemented by a servo motor driving an unwinding roller, and the winding device 3 includes but is not limited to being implemented by a servo motor driving a winding roller.

[0067] Specifically, the film 4 is an electronic protection film.

[0068] In this embodiment, the servo motor can be comprehensively controlled by the control module to keep the film 4 taut during the coating process.

[0069] In this embodiment, the servo motor is not shown.

[0070] In this embodiment, the feed port 13 may be connected to a delivery pipe to continuously deliver the slurry into the feed port 13 .

[0071] In this embodiment, other devices including but not limited to a dryer and a thickness gauge for coating the electronic protective film are provided between the unwinding device 2 and the rewinding device 3 .

[0072] At least one other disclosed embodiment also provides a working method of a slit coating head, including: controlling the flow rate of the slurry in the slave channel 112 through the adjustment mechanism 12, that is, when the flow rate of the slurry in the corresponding slave channel in the slit coating head 1 exceeds the preset flow rate, moving the flow resistance adjustment column in the slave channel downward to reduce the effective cross-sectional area of ​​the feed port of the slave channel, thereby increasing the resistance of the slurry flowing into the slave channel; and when the effective cross-sectional area of ​​the feed port of the slave channel 112 is adjusted to the minimum threshold and the flow rate still exceeds the preset flow rate, continuing to move the flow resistance adjustment column downward so that the first opening of the flow resistance adjustment column is connected to the feed port of the slave channel 112, so that the slurry flows from the buffer channel into the slave channel.

[0073] At least one other disclosed embodiment further provides a method for operating a coating machine, comprising: coating a film 4 unwound by an unwinding device 2 while passing through a slit coating head 1 , and then rewinding the coated film 4 by a rewinding device 3 .

[0074] In summary, the slit coating head comprises: an upper coating die head and a lower coating die head; a coating slit is formed between the upper and lower coating dies; the upper coating die head is provided with a main channel and a plurality of secondary channels; the main channel is connected to each secondary channel; and each secondary channel is provided with an adjustment mechanism, the adjustment mechanism being configured to detect the flow rate of the slurry in the corresponding secondary channel to adjust the flow rate of the slurry in the secondary channel. The dynamic adjustment method of the adjustment mechanism effectively avoids pressure fluctuations of the slurry flow while adjusting the flow rate of the secondary channel, thereby ensuring the consistency of the coating slit on the film.

[0075] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0076] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, terms such as "first", "second" and other numerical terms do not imply an order or sequence when used herein unless expressly indicated above. Therefore, without departing from the teachings of the example embodiments, the first element, component, region, layer or section discussed above may be referred to as a second element, component, region, layer or section.

[0077] Spatially relative terms, such as "inside," "outside," "below," "beneath," "below," "above," "upper," etc., may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features.

[0078] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A slot coating head, characterized in that: include: an upper coating die (11) and a lower coating die (15); A coating slit (16) is formed between the upper coating die (11) and the lower coating die (15); wherein The upper coating die head (11) is provided with a main flow channel (111) and a plurality of secondary flow channels (112); The main flow channel (111) is connected to each of the secondary flow channels (112); and Each of the slave flow channels (112) is provided with a regulating mechanism (12), and the regulating mechanism (12) is configured to detect the flow rate of the slurry in the corresponding slave flow channel (112) to adjust the flow rate of the slurry in the slave flow channel (112); The regulating mechanism (12) comprises: a flow-blocking regulating column (121) and a flow sensor (122); The flow sensor (122) is arranged at the discharge port of the flow channel (112); and The flow-blocking regulating column (121) is slidably arranged in the secondary flow channel (112); wherein A buffer flow channel (123) is provided inside the flow-blocking adjustment column (121); a first opening (124) of the buffer flow channel is located on the arc-shaped side wall of the flow-blocking adjustment column (121); and a second opening (125) is located on the inclined bottom wall of the flow-blocking adjustment column (121); The flow-resistance adjustment column (121) is configured to slide according to flow data acquired by the flow sensor (122), thereby adjusting the effective cross-sectional area of ​​the feed port of the flow channel (112); and When the flow-blocking regulating column (121) moves downward at the starting position to reduce the cross-sectional area from the flow channel feed port, the second opening (125) of the buffer flow channel is configured to absorb pressure fluctuations generated when the flow-blocking regulating column (121) moves; When the flow resistance regulating column (121) moves to the point where the feed port of the slave flow channel is closed, the first opening (124) of the buffer flow channel is connected to the feed port of the slave flow channel. At this time, the buffer flow channel is configured to provide a flow path for the slurry.

2. The slit coating head according to claim 1, wherein The bottom end surface of the flow resistance regulating column is arranged to be inclined so as to guide the slurry entering from the flow channel feed port to smoothly transition from horizontal flow to vertical flow.

3. The slit coating head according to claim 2, wherein: The regulating mechanism (12) further includes: a control module; The control module is electrically connected to the flow sensor (122) and the driving member (120) of the flow resistance adjustment column (121) respectively; wherein The control module is configured to obtain flow data detected by the flow sensor (122), and to control the start and stop of the driving member (120) of the flow-blocking adjustment column (121) according to the flow data, thereby adjusting the position of the flow-blocking adjustment column (121) in the flow channel (112).

4. The slit coating head according to claim 1, wherein A receiving cavity (151) is formed between the upper coating die (11) and the lower coating die (15); The accommodating cavity (151) is communicated with the coating slit (16), and the slurry in the accommodating cavity (151) flows out from the coating slit (16) for coating.

5. A coating machine, characterized in that: include: An unwinding device (2), a rewinding device (3) and a slit coating head (1); The slit coating head (1) is suitable for adopting the slit coating head (1) as described in any one of claims 1 to 4.

6. The coating machine according to claim 5, wherein The slit coating head (1) is arranged between the unwinding device (2) and the winding device (3); The unwinding device (2) is configured to unwind a film (4), and the slit coating head (1) coats the unwinding film (4); and The winding device (3) is configured to wind up the coated film (4).

7. A method for operating a slit coating head, characterized in that: include: Using the slit coating head (1) as described in any one of claims 1 to 4; as well as The flow rate of the slurry in the flow channel (112) is controlled by the regulating mechanism (12), that is, When the flow rate of the slurry in the corresponding slave flow channel in the slit coating head (1) exceeds a preset flow rate, the flow resistance regulating column (121) in the slave flow channel is moved downward to reduce the effective cross-sectional area of ​​the slave flow channel feed port, thereby increasing the resistance of the slurry flowing into the slave flow channel; and When the flow rate still exceeds the preset flow rate after the effective cross-sectional area of ​​the feed port of the slave flow channel (112) is adjusted to the minimum threshold, the flow resistance regulating column (121) is further moved downward so that the first opening of the flow resistance regulating column (121) is connected to the feed port of the slave flow channel (112), so that the slurry flows from the buffer channel into the slave flow channel.

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