A viscosity control device and a roll coating device in a roll coating process

Abstract

The utility model relates to a kind of viscosity control device and roll coating device in roll coating procedure, the viscosity control device is installed on roll coating device, the viscosity control device includes catcher and capillary, the roll coating device includes roll and tank, the roll is installed at the top open mouth of tank, downward capillary is installed on the bottom groove wall, internal space is communicated with capillary, catcher is installed below, the solution contained in the tank drops liquid bead by capillary, the drop frequency of the liquid bead is captured by catcher to judge the change of solution viscosity in tank. Compared with prior art, the utility model monitors solution viscosity change in roll coating process.

Description

Technical Field

[0001] This utility model belongs to the field of roller coating technology, and relates to a viscosity control device and a roller coating device in the roller coating process. Background Technology

[0002] In the printing and coating industries, roll coating is a common process. This process requires a relatively high viscosity of the solution, achieving good printing or coating results only within a narrow range. If the viscosity is too high or too low, the solution's leveling properties change, compromising coating thickness and print appearance. Furthermore, for proper winding after roll coating, the solvent in the coating solution on the film needs to evaporate rapidly, achieving fast drying at high winding speeds. This means the solvent in the solution has a relatively low boiling point, leading to easy evaporation of the solvent in the trough during the rapid rolling process, causing significant changes in the solution's viscosity. Therefore, it is crucial to monitor and control the solution viscosity regularly during roll coating to ensure optimal processing results.

[0003] Currently, a common method for viscosity control is to use a circulating pump to circulate the solution in the tank with the prepared solution, assuming that the viscosity in the tank will not change. However, this approach does not accurately reflect changes in viscosity, meaning the feedback accuracy for viscosity changes is poor, which has drawbacks in actual production. Furthermore, measuring the viscosity of the solution in real time using instruments such as viscometers is complex, impractical, and not easily applied to production.

[0004] Patent CN105899364A discloses a flexographic printing system with solvent replenishment, which uses a flexographic printing plate to produce printed patterns on a substrate; it uses an ink recycling system to reduce the variability of system performance caused by changes in ink viscosity; a recycling pump moves ink through an ink recycling line connected to an ink reservoir; a metering pump adds solvent at a controlled flow rate from a solvent replenishment chamber into the ink recycling line, thus providing replenished ink; the replenished ink is returned to the ink reservoir through a distribution pipe including multiple supply ports at multiple spaced locations across the width of the ink reservoir; a control system controls the flow rate of the solvent provided by the metering pump. However, this patent also uses a viscometer to measure the viscosity of the solution in real time, which is a complex process and has limited practical guidance for production. Utility Model Content

[0005] The purpose of this invention is to overcome at least one of the defects in the prior art and provide a viscosity control device and a roller coating device for the roller coating process. This invention monitors the change in solution viscosity during the roller coating process.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] One of the technical solutions of this utility model is to provide a viscosity control device in a roller coating process. The viscosity control device is installed on a roller coating device and includes a trap and a capillary tube. The roller coating device includes a roller and a material trough. A roller is installed at the top opening of the material trough, and a downward-facing capillary tube is installed on the bottom wall of the trough. The internal space is connected to the capillary tube, and a trap is installed below. The solution contained in the material trough drips into droplets through the capillary tube. The dripping frequency of the droplets is captured by the trap to determine the change in the viscosity of the solution in the material trough.

[0008] Furthermore, a base is provided on the bottom wall of the material tank, and a capillary channel for the flow of solution is opened inside the capillary tube. An enlarged base is provided at one end. The capillary tube is inserted into the base through the base to be installed on the bottom wall of the material tank, which facilitates the replacement of different capillary tubes when changing the type of solution in the material tank. The internal space of the material tank is connected to the capillary channel to drip the solution into the material tank.

[0009] Furthermore, different viscosities of solutions can be matched by replacing capillary tubes with different pore sizes, ultimately forming a slow dripping speed and dripping in the form of liquid droplets. Therefore, the amount of solution flowing out of the capillary tube is small and can be ignored for the overall solution in the tank. The opening diameter of the capillary tube is 0.3 to 1 mm.

[0010] Furthermore, the viscosity control device also includes a liquid collecting cylinder, which is located below the capillary tube to collect the solution dripping from the material tank.

[0011] Furthermore, the viscosity control device also includes a solvent supply cylinder containing solvent. The material tank is connected to the solvent supply cylinder via a pipeline, and the solution in the material tank is replenished with solvent through the supply cylinder.

[0012] Furthermore, the viscosity control device also includes a circulation pump, which is installed on the pipeline to control the solvent to be pumped from the solvent supply cylinder into the feed tank.

[0013] Furthermore, the viscosity control device also includes a control component, the trap is connected to the control component, and the dripping frequency of the liquid droplets collected by the trap is fed back to the control component to determine the change in the viscosity of the solution in the tank.

[0014] Furthermore, the circulating pump is connected to the control component, and the timing of pumping the solution from the solvent supply cylinder into the material tank is determined based on the change in the viscosity of the solution in the material tank. The control component controls the circulating pump to pump the solvent from the supply cylinder into the material tank at the appropriate time to adjust the viscosity of the solution.

[0015] The catcher captures the droplet frequency in real time and feeds the information back to the control component. The control component uses the droplet frequency to determine the change in the viscosity of the solution in the tank, and then controls the circulating pump to replenish the solvent in the feed cylinder to the tank, thereby correcting the viscosity of the solution in the tank.

[0016] One of the technical solutions of this utility model is to provide a roller coating apparatus, which includes the aforementioned viscosity control device. The viscosity control device is installed on the roller coating apparatus. The roller includes a pressure roller and a printing roller. The roller body of the printing roller is disposed in a material trough, and its shaft passes through the two side walls of the material trough. The printing roller rotates within the material trough, and the pressure roller is installed above the material trough and rotates.

[0017] The printing roller uses a solution in the trough to print the pattern on the film, or to coat the film with the solution in the trough, and a pressure roller applies pressure to the other side of the film.

[0018] Furthermore, the roller coating device also includes a fixed base on which a material trough is installed, and the shafts of the pressure roller and the printing roller rotate through the fixed base.

[0019] As a preferred technical solution, a material trough is installed between a pair of fixed seats.

[0020] The principle of the viscosity control device in the roller coating process is as follows:

[0021] According to Poiseuille's law, the flow rate in the capillary can be expressed as:

[0022]

[0023] Where Q is the volumetric flow rate of the liquid, R is the radius of the capillary, ΔP is the pressure difference between the two ends of the capillary, η is the viscosity of the liquid, and L is the length of the capillary.

[0024] When R becomes small enough, the liquid flowing out of the capillary is not continuous due to surface tension, but rather drips in the form of droplets. The frequency of these droplets can be determined by the following formula.

[0025]

[0026] Where t is the outflow time of the liquid, V is the outflow volume of the liquid, and n is the number of liquid droplets. * is the volume of each droplet, and f is the frequency of the droplet falling.

[0027] By combining equations 1) and 2), we can obtain:

[0028]

[0029] in,

[0030] Regarding the aforementioned ΔP, it is related to the depth of the tank, i.e., ΔP = ρgh. Since the liquid density ρ is constant, ΔP only depends on the liquid depth h. For a single tank, the solution is replenished promptly after consumption, and the solution feeding depth is generally fixed, so ΔP essentially remains unchanged. * The volume of each droplet is related to the surface tension of each liquid and remains constant for a given solution; R and L are constant values.

[0031] Therefore, κ is a constant, and the viscosity η of the liquid is inversely proportional to the droplet frequency f. As the solution evaporates, the viscosity η increases and the droplet frequency f decreases. After the catcher recognizes this, it automatically controls the circulating pump to pump the material and maintain the stability of the solution viscosity in the tank.

[0032] The printing roller is constantly rolling, and the solution in the trough will always be evenly dispersed, without any uneven viscosity distribution of the solution in the trough. Therefore, the measured data is relatively accurate.

[0033] One of the technical solutions of this utility model is to provide a viscosity control method in a roller coating process. This method uses the aforementioned viscosity control device to control the viscosity in the roller coating process, and includes the following steps:

[0034] S1. Prepare the ink or coating solution to be roller coated and adjust it to the expected viscosity;

[0035] S2. Pour the solution into the material tank;

[0036] S3. Select capillary tubes with specific pore sizes based on the viscosity of the solution; for solutions with high viscosity, select capillary tubes with large pore sizes; for solutions with low viscosity, select capillary tubes with small pore sizes; use the form of droplets as the criterion for judgment, and ensure that the droplet frequency is appropriate.

[0037] S4. The control component reads the drip frequency value measured by the trap;

[0038] S5. The default dripping frequency of the solution is set to this measured value in the control component, and the dripping frequency is monitored in real time during the printing or coating process. The monitored dripping frequency is compared with the default dripping frequency. If the dripping frequency decreases, it indicates that the viscosity of the solution has increased. The control component will then control the circulation pump to replenish the solvent to correct the viscosity of the solution.

[0039] S6. Continue printing or coating.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) This utility model proposes a device for monitoring the viscosity of a solution during the roller coating process. It only requires installing a capillary tube on the trough to allow the solution to drip. The frequency of the dripping of the liquid droplets is captured by a catcher to determine the change in the viscosity of the solution in the trough. The solvent is pumped from the feed cylinder into the trough in real time by a circulating pump to correct the solution viscosity, thereby achieving the purpose of accurately controlling the solution viscosity.

[0042] (2) This utility model is simple, easy to implement, low in cost, and highly practical. It is highly applicable to production and can be realized through simple modification of roller coating equipment. It has a good guiding role in printing and coating production. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the viscosity control device in the roller coating process of this utility model embodiment;

[0044] Figure 2 This is a schematic diagram of the capillary tube installation in an embodiment of this utility model.

[0045] Explanation of markings in the diagram:

[0046] 1—Fixed seat, 2—Film, 3—Pressure roller, 4—Printing roller, 5—Feed trough, 6—Control component, 7—Catcher, 8—Collection cylinder, 9—Liquid droplet, 10—Capillary tube, 11—Feeding cylinder, 12—Circulation pump. Detailed Implementation

[0047] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0048] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In addition, the terms "first," "second," "third," etc., used to describe a common object only indicate different instances of the same object, and are not intended to imply that the objects described in this way must be in a given order, whether temporally, spatially, sequentially, or in any other way.

[0049] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0050] During the printing or coating process, the film 2 moves at high speed, and the printing roller 4 transfers the ink or coating solution from the grooves on it onto the film 2 by rotating, thus forming the printing or coating process. As the printing roller 2 rotates at high speed, on the one hand, the solution in the material tank 5 will be gradually consumed, so a circulation system (not shown in the figure) can be used to replenish the material; on the other hand, the volatile solvent in the material tank 5 will evaporate rapidly, causing the viscosity of the solution to increase significantly. If the viscosity is not corrected, the appearance of the printing or coating will be deteriorated.

[0051] Example:

[0052] A viscosity control device for a roller coating process, such as Figure 1 and Figure 2 As shown, the viscosity control device installed on the roller coating device includes a trap 7 and a capillary tube 10. The roller coating device includes a roller and a trough 5. A roller is installed at the top opening of the trough 5, and a downward-facing capillary tube 10 is installed on the bottom wall of the trough. The internal space is connected to the capillary tube 10. A trap 7 is installed below. The solution contained in the trough 5 drips into droplets 9 through the capillary tube 10. The dripping frequency of the droplets 9 is captured by the trap 7 to determine the change in the viscosity of the solution in the trough 5.

[0053] A base is provided on the bottom wall of the material tank 5. The capillary tube 10 has a capillary channel for the flow of solution inside. An enlarged base is provided at one end. The capillary tube 10 is inserted into the base through the base to be installed on the bottom wall of the material tank 5. This makes it convenient to replace different capillary tubes 10 when changing the type of solution in the material tank 5. The internal space of the material tank 5 is connected to the capillary channel to drip the solution into the material tank.

[0054] Different viscosities of solutions can be matched by replacing capillary tubes 10 with different pore sizes, ultimately forming a slow dripping speed and dripping in the form of liquid droplets 9. Therefore, the amount of solution flowing out of capillary tube 10 is small and can be ignored for the overall solution in the material tank 5. The opening pore size of the capillary tube is 0.3 to 1 mm, and is preferably 0.6 mm in this embodiment.

[0055] The viscosity control device also includes a liquid collecting cylinder 8, which is located below the capillary tube 10 to collect the solution dripping from the material tank 5.

[0056] The viscosity control device also includes a solvent supply cylinder 11, which contains solvent. The material tank 5 is connected to the solvent supply cylinder 11 through a pipeline, and the solution in the material tank 5 is replenished with solvent through the supply cylinder 11.

[0057] The viscosity control device also includes a circulation pump 12, which is installed on the pipeline and controls the solvent to be pumped from the solvent supply cylinder 11 into the feed tank 5.

[0058] The viscosity control device also includes a control component 6, and a trap 7 is connected to the control component 6. The dripping frequency of the liquid droplets 9 collected by the trap 7 is fed back to the control component 6 to determine the change in the viscosity of the solution in the tank 5.

[0059] The circulating pump 12 is connected to the control component 6. The timing of pumping the solution from the solvent supply cylinder 11 into the material tank 5 is determined based on the change in the viscosity of the solution in the material tank 5. The control component 6 controls the circulating pump 12 to pump the solvent from the solvent supply cylinder 11 into the material tank 5 at the appropriate time to adjust the viscosity of the solution.

[0060] The catcher 7 captures the dripping frequency of the liquid droplets 9 in real time and feeds the information back to the control component 6. The control component 6 uses the dripping frequency to determine the change in the viscosity of the solution in the tank 5, thereby controlling the circulating pump 12 to replenish the solvent in the solvent supply cylinder 11 to the tank 5, so as to correct the viscosity of the solution in the tank 5.

[0061] A roller coating apparatus includes the aforementioned viscosity control device, which is mounted on the roller coating apparatus. The rollers include a pressure roller 3 and a printing roller 4. The roller body of the printing roller 4 is disposed in a material trough 5, and its shaft passes through the two side walls of the material trough 5. The printing roller 4 rotates within the material trough 5, while the pressure roller 3 is mounted above the material trough 5 and rotates.

[0062] The printing roller 4 uses the solution contained in the material tank 5 to print the pattern on the printing roller 4 onto the film 2, or to coat the solution contained in the material tank 5 onto the film 2, and pressure is applied to the other side of the film 2 using the pressure roller 3.

[0063] The roller coating device also includes a fixed base 1, with a material trough 5 installed between a pair of fixed bases 1, and the shafts of the pressure roller 3 and the printing roller 4 rotate through the fixed base 1.

[0064] The principle of the viscosity control device in the above-mentioned roller coating process is as follows:

[0065] According to Poiseuille's law, the flow rate within capillary tube 10 can be expressed as:

[0066]

[0067] Where Q is the volumetric flow rate of the liquid, R is the radius of capillary 10, ΔP is the pressure difference between the two ends of capillary 10, η is the viscosity of the liquid, and L is the length of capillary 10.

[0068] When R becomes small enough, the liquid flowing out of capillary 10 is not continuous due to surface tension, but rather drips in the form of droplets 9. The dripping frequency of droplets 9 is given by the following formula.

[0069]

[0070] Where t is the outflow time of the liquid, V is the outflow volume of the liquid, n is the number of liquid droplets 9 falling, and V * is the volume of each droplet 9, and f is the frequency of droplet 9 falling.

[0071] By combining equations 1) and 2), we can obtain:

[0072]

[0073] in,

[0074] Regarding the aforementioned ΔP, it is related to the depth of the tank 5, i.e., ΔP = ρgh. Since the liquid density ρ is constant, ΔP is only related to the liquid depth h. For a single tank 5, the solution is replenished promptly after consumption, and the solution feeding depth is generally fixed, so ΔP remains essentially unchanged. * The volume of each droplet 9 is related to the surface tension of each liquid and remains constant for a given solution; R and L are constant values.

[0075] Therefore, κ is a constant, and the viscosity η of the liquid is inversely proportional to the dripping frequency f of the liquid droplets 9. As the solution evaporates, the viscosity η increases and the dripping frequency f decreases. After the catcher 7 identifies this, it automatically controls the circulating pump 12 to pump the material, maintaining the stability of the solution viscosity in the tank 5.

[0076] The printing roller 5 is constantly rolling, and the solution in the material tank 5 will always be evenly dispersed, without the phenomenon of uneven viscosity distribution of the solution in the material tank 5. Therefore, the measured data is relatively accurate.

[0077] A viscosity control method in a roller coating process, using the aforementioned viscosity control device to control viscosity in the roller coating process, comprises the following specific steps:

[0078] S1. Prepare the ink or coating solution to be roller coated and adjust it to the expected viscosity;

[0079] S2. Pour the solution into the material tank 5;

[0080] S3. Select a capillary tube 10 with a specific pore size according to the viscosity of the solution; for solutions with high viscosity, select a capillary tube 10 with a large pore size; for solutions with low viscosity, select a capillary tube 10 with a small pore size; the criterion is that the solution drips in the form of droplets 9, and the dripping frequency is appropriate.

[0081] S4. Control component 6 reads the drip frequency value measured by the trap 7;

[0082] S5. The default dripping frequency of the solution is set to this measured value in the control component 6, and the dripping frequency is monitored in real time during the printing or coating process. The monitored dripping frequency is compared with the default dripping frequency. If the dripping frequency decreases, it indicates that the viscosity of the solution increases. Then the control component 6 will control the circulation pump 12 to replenish the solvent to correct the viscosity of the solution.

[0083] S6. Continue printing or coating.

[0084] The above description of the embodiments is provided to enable those skilled in the art to understand and use the utility model. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present utility model is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present utility model without departing from its scope should be within the protection scope of the present utility model.

Claims

1. A viscosity control device for a roller coating process, characterized in that, The viscosity control device is installed on the roller coating device. The viscosity control device includes a trap (7) and a capillary tube (10). The roller coating device includes a roller and a trough (5). A roller is installed at the top opening of the trough (5). A downward-facing capillary tube (10) is installed on the bottom wall of the trough. The internal space is connected to the capillary tube (10). A trap (7) is installed below. The solution contained in the trough (5) drips into droplets (9) through the capillary tube (10). The dripping frequency of the droplets (9) is captured by the trap (7) to determine the change in viscosity of the solution in the trough (5).

2. The viscosity control device in a roller coating process according to claim 1, characterized in that, A base is provided on the bottom wall of the material tank (5). The capillary tube (10) has a capillary channel for the flow of solution inside. An enlarged base is provided at one end. The capillary tube (10) is inserted into the base through the base to be installed on the bottom wall of the material tank (5). The internal space of the material tank (5) is connected to the capillary channel.

3. The viscosity control device in a roller coating process according to claim 2, characterized in that, The opening diameter of the capillary is 0.3 to 1 mm.

4. The viscosity control device in a roller coating process according to claim 1, characterized in that, The viscosity control device also includes a liquid collecting cylinder (8), which is located below the capillary tube (10).

5. The viscosity control device in a roller coating process according to claim 1, characterized in that, The viscosity control device also includes a solvent supply cylinder (11), which contains solvent, and the material tank (5) is connected to the solvent supply cylinder (11) through a pipeline.

6. The viscosity control device in a roller coating process according to claim 5, characterized in that, The viscosity control device also includes a circulation pump (12), and the circulation pump (12) is installed on the pipeline.

7. A viscosity control device for a roller coating process according to claim 6, characterized in that, The viscosity control device further includes a control component (6), and the catcher (7) is connected to the control component (6).

8. The viscosity control device in a roller coating process according to claim 7, characterized in that, The circulating pump (12) is connected to the control assembly (6).

9. A roller coating apparatus, characterized in that, The roller coating apparatus includes a viscosity control device as described in any one of claims 1 to 8, the viscosity control device being mounted on the roller coating apparatus, the roller including a pressure roller (3) and a printing roller (4), the roller body of the printing roller (4) being disposed in a material trough (5), the shaft passing through the two side walls of the material trough (5), the printing roller (4) rotating in the material trough (5), and the pressure roller (3) being mounted above the material trough (5) and rotating.

10. A roller coating apparatus according to claim 9, characterized in that, The roller coating device also includes a fixed seat (1), on which a material trough (5) is installed, and the shafts of the pressure roller (3) and the printing roller (4) rotate through the fixed seat (1).

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