Jet coating mechanism

Abstract

The application discloses a spraying coating mechanism and relates to the papermaking field. In the application, a back roll is used for supporting a paper web, the rotating axis of the back roll is parallel to a horizontal plane; a spraying head is located below the back roll and sprays coating material to the side close to the back roll in a spraying direction, the back roll is used for coating the paper web in cooperation with the spraying head, the extension line of the spraying direction intersects with the circumferential surface of the back roll at a first position, the back roll is configured to increase the distance between the spraying port of the spraying head and the first position by reducing the diameter and keeping the position of the lowest part on the circumferential surface of the back roll unchanged in the vertical direction, and the spraying head is configured to increase the distance between the spraying port of the spraying head and the first position by adjusting the included angle between the spraying direction and the horizontal plane; a liquid supply device is used for storing the coating material and is connected with the spraying head so as to deliver the coating material to the spraying head. The application improves the phenomenon of coating material splashing back and the phenomenon of poor coating of the paper web.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of papermaking, in particular to a spraying coating mechanism. BACKGROUND

[0002] In the process of papermaking, the paper web needs to be coated, and the most critical step is coating spraying. In the process of coating spraying, coating back splash is prone to occur, and then the phenomenon of poor paper web coating occurs. SUMMARY

[0003] To solve the above technical problems, one technical solution adopted by the present application is: a spraying coating mechanism, comprising:

[0004] A backing roll for supporting the paper web, the rotation axis of the backing roll being parallel to the horizontal plane;

[0005] A spraying head located below the backing roll, spraying coating on the side close to the backing roll in the spraying direction, the extension line of the spraying direction intersecting the circumferential surface of the backing roll at a first position, the backing roll being configured to increase the distance between the spraying port of the spraying head and the first position by reducing the diameter and keeping the position of the lowest part in the vertical direction on the circumferential surface of the backing roll unchanged after the diameter is reduced, the spraying head being configured to increase the distance between the spraying port of the spraying head and the first position by adjusting the included angle between the spraying direction and the horizontal plane; and

[0006] A liquid supply device for storing the coating and connected to the spraying head to deliver the coating to the spraying head.

[0007] Further technical solutions are that the backing roll is used to support the paper web on the side close to or away from the spraying head.

[0008] Further technical solutions are that the diameter of the backing roll after the diameter is reduced is 1460-1480mm.

[0009] Further technical solutions are that the included angle between the spraying direction and the horizontal plane after the adjustment is 14-20°.

[0010] Further technical solutions are that the low shear viscosity of the coating is 1900-2000cPs.

[0011] Further technical solutions are that the distance between the spraying port of the spraying head and the first position is 1.5-3.5cm.

[0012] Further technical solutions are that the liquid supply device comprises:

[0013] A coating supply member for storing the coating;

[0014] a plurality of filters, each of the plurality of filters being connected with the paint supply and the spray head, so that the paint supply delivers the paint to the spray head through the filters, and the amount of paint in the filters for delivering the paint to the spray head is greater than or equal to a preset paint amount, the preset paint amount being the amount of paint delivered from the paint supply to the filters within a first time, the first time being greater than or equal to 20s, and the pore size of the filter screen in the filters being 130-170μm.

[0015] Further, the liquid supply device further comprises:

[0016] a clean water supply connected with the filters;

[0017] a waste liquid collection connected with the filters, and used in cooperation with the clean water supply to clean the filters; and

[0018] a pressure booster connected with the filters.

[0019] Further, the filters are connected with the paint supply through a feed valve and an exhaust valve, and are connected with the spray head through a feed valve, and are connected with a flush valve, the flush valve is connected with the paint supply through a return valve, and is connected with the clean water supply through a water valve, and is connected with the waste liquid collection through a drain valve.

[0020] Further, the pressure booster comprises a pressure booster body and a pressure valve, the pressure booster body is connected with the pressure valve, the pressure valve is connected with the filters through a connection valve, so that the filters are connected with the pressure booster through the pressure valve and the connection valve, and the connection valve connects one end of the pressure valve with the waste liquid collection.

[0021] By reducing the diameter of the back roller, the distance between the spray port of the spray head and the first position is increased, and the angle between the spray direction and the horizontal plane is reduced, so that the phenomenon of paint splashing is improved, and the phenomenon of poor paper web coating is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate embodiments consistent with the application and, together with the description, further serve to explain the principles of the application.

[0023] Figure 1 Structure diagram of the spraying coating mechanism in some embodiments of the application;

[0024] Figure 2 Structure diagram of the spraying coating mechanism in some embodiments of the application; Figure 1 Structure diagram of the spraying coating mechanism in some embodiments of the application;

[0025] Figure 3 Structure diagram of the spraying coating mechanism in some embodiments of the application; Figure 1 Structure diagram of the spraying coating mechanism in some embodiments of the application; Figure 2 Structure diagram of the spraying coating mechanism in some embodiments of the application;

[0026] Figure 4 Structure diagram of the spraying coating mechanism in some embodiments of the application; Figure 1 Structure diagram of the spraying coating mechanism in some embodiments of the application; Structure diagram of the spraying coating mechanism in some embodiments of the application;

[0027] Structure diagram of the spraying coating mechanism in some embodiments of the application; Figure 5 Structure diagram of the spraying coating mechanism in some embodiments of the application; Structure diagram of the spraying coating mechanism in some embodiments of the application;

[0028] Structure diagram of the spraying coating mechanism in some embodiments of the application; Figure 6 Structure diagram of the spraying coating mechanism in some embodiments of the application; Structure diagram of the spraying coating mechanism in some embodiments of the application;

[0029] Structure diagram of the spraying coating mechanism in some embodiments of the application; Figure 7 Structure diagram of the spraying coating mechanism in some embodiments of the application. DETAILED DESCRIPTION

[0030] The application will be described in further detail in connection with the drawings and embodiments. It is specifically intended that the following description should be considered as an illustrative and not a limiting description of the application. Similarly, it is contemplated that the embodiments described herein are merely exemplary of the application and that other embodiments can fall within the scope of the application. It is contemplated that any embodiment described herein can be combined with other embodiments.

[0031] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily all directed to the same embodiment, or to a single alternative embodiment. It is expressly understood that any of the embodiments described herein can be combined with any of the other embodiments unless specifically noted otherwise.

[0032] The present application discloses a spraying coating mechanism, which can improve the phenomenon of paint splashing and the phenomenon of poor coating of paper web caused by paint splashing. The paper web (which can be referred to as "paper", "paper", or "raw paper") after being coated with paint can be used as various printing paper or product packaging paper. The type and use of the paper web are not limited and can be determined according to the needs of those skilled in the art. Here, white card paper can be coated as an example.

[0033] Please refer to Figure 1 , Figure 1 is a schematic view of the spraying coating mechanism in some embodiments of the present application. The spraying coating mechanism 100 can include a backing roll 10 for supporting the paper web and a coating system 20 cooperating with the backing roll 10 to coat the paper web. The circumferential surface of the backing roll 10 can be in contact with the paper web to support the paper web during the conveying process. In addition, the backing roll 10 is in pressure contact with the paper web during the conveying process. It can be understood that in order to realize the conveying of the paper web, the spraying coating mechanism 100 can also include other rotating rolls, and is not limited to the backing roll 10. For details, please refer to the technical solutions known to those skilled in the art.

[0034] Please refer to Figure 1 , the backing roll 10 has an axis of rotation 11 and can rotate around the axis of rotation 11. The axis of rotation 11 can be parallel to the horizontal plane. Of course, in actual life, this axis of rotation 11 will be affected by the placement error of the spraying coating mechanism 100 or the installation error of the backing roll 10, and will not be parallel to the horizontal plane, and thus within the error range accepted by those skilled in the art, it should still be considered that the axis of rotation 11 is parallel to the horizontal plane. In some embodiments, in Figure 1 , the paper web can be conveyed from left to right, and the backing roll 10 can rotate clockwise around the axis of rotation 11. In some embodiments, in Figure 1 , the paper web can be conveyed from right to left, and the backing roll 10 can rotate counterclockwise around the axis of rotation 11.

[0035] Please refer to Figure 1 , the coating system 20 can include a coating head 21 cooperating with the backing roll 10 to coat the paper web and a liquid supply device 22 connected to the coating head 21 and providing paint for the coating head 21. The liquid supply device 22 can deliver paint to the coating head 21. The coating head 21 then performs coating, and the backing roll 10 cooperates to complete the coating of the paper web.

[0036] The coating head 21 can include a mounting base 211, a spraying head 212 in sliding connection with the mounting base 211, and a hand wheel 213 in rotational connection with the mounting base 211 and used to drive the spraying head 212 to slide. The spraying head 212 can slide relative to the mounting base 211 through a structure such as a sliding rail, a sliding groove, a sliding block, etc. The spraying head 212 can spray coating in a spraying direction. The spraying direction can be consistent or parallel with the direction in which the spraying head 212 slides relative to the mounting base 211, or can form an angle β with the horizontal plane. The hand wheel 213 can be installed on the mounting base 211 through a rotating shaft, clamping, screwing, etc., and can drive the spraying head 212 to slide through rotation. The specific connection mode of the hand wheel 213 and the spraying head 212 can refer to the technical solutions well known to those skilled in the art. In some embodiments, the hand wheel 213 is in meshing connection with the spraying head 212.

[0037] Referring to Figure 1 , the coating head 21 can have a safety distance L from the backing roll 10, so as to ensure that the arrangement of the coating head 21 does not affect the paper web conveying, coating, etc., or does not affect the backing roll 10 or other structures in the spraying coating mechanism 100. Of course, the safety distance L can also be specifically arranged or adjusted according to other requirements. In some embodiments, the safety distance L can be defined as the distance between the structure of the coating head 21 other than the spraying head 212 and the backing roll 10. In some embodiments, the safety distance L can be defined as the distance between the mounting base 211 and the backing roll 10. In some embodiments, the safety distance L can be 10-20 cm. In some embodiments, the safety distance L can be 15 cm.

[0038] Referring to Figure 1 , the spraying head 212 can be located below the backing roll 10 and can spray coating to the side close to the backing roll 10 in the spraying direction. The spraying direction can extend and can extend to the first position 101. The first position 101 can be the position where the spraying direction intersects with the circumferential surface of the backing roll 10. The distance between the spraying port of the spraying head 212 and the first position 101 can be M.

[0039] Referring to Figure 1 , the backing roll 10 supports the paper web on the side away from the spraying head 212. The spraying head 212 can directly spray coating to the first position 101 of the backing roll 10. When the backing roll 10 rotates, the pressure contact between the backing roll 10 and the paper web can cause the coating to be transferred to the paper web under pressure, so as to complete the paper web coating. It can be understood that, in the paper web coating process, not only the spraying and transferring processes can be performed, but also other steps can be performed, which will not be described herein.

[0040] Referring to Figure 2 , Figure 2 , the spraying head 212 can spray coating to the first position 101 of the backing roll 10. When the backing roll 10 rotates, the pressure contact between the backing roll 10 and the paper web can cause the coating to be transferred to the paper web under pressure, so as to complete the paper web coating. It can be understood that, in the paper web coating process, not only the spraying and transferring processes can be performed, but also other steps can be performed, which will not be described herein. Figure 1Structure diagram of the spraying coating mechanism 100 in other embodiments. The backing roll 10 can support the paper web on the side close to the spraying head 212. The spraying head 212 can directly spray the coating material onto the paper web to complete the paper web coating. It can be understood that, in the paper web coating process, steps such as spraying can be performed, and other steps can also be performed, which are not described herein. In some embodiments, in the case of Figure 2 , the paper web can be conveyed from left to right, and the backing roll 10 can rotate counterclockwise around the rotation axis 11. In some embodiments, in the case of Figure 2 , the paper web can be conveyed from right to left, and the backing roll 10 can rotate clockwise around the rotation axis 11.

[0041] Please refer to Figure 1 and Figure 2 , when the included angle β decreases, the first position 101 is closer to the right side, and the distance M will increase. In some embodiments, the distance between the spraying port of the spraying head 212 and the first position 101 can be increased by adjusting the included angle β between the spraying direction and the horizontal plane. Through research by the inventor, in the actual paper web coating process, the decrease of the included angle β can improve the coating material splash phenomenon. In some embodiments, the included angle β is 25°. In some embodiments, the included angle β is 20°. In some embodiments, the included angle β is 16°. In the research process, the coating material splash degree when the included angle β is 25° is greater than the coating material splash degree when the included angle β is 20°, and the coating material splash degree when the included angle β is 20° is greater than the coating material splash degree when the included angle β is 16°. In some embodiments, the included angle β is 14-20°. In some embodiments, the included angle β is 18°. In some embodiments, the included angle β is 17°. In some embodiments, the included angle β is 14°. In some embodiments, the included angle β is 15°. In some embodiments, the included angle β is 19°.

[0042] In some embodiments, in order to avoid the phenomenon of insufficient spraying pressure of the spraying head 212 caused by the decrease of the included angle β, the distance M can be adjusted to 1.5-3.5 cm. In some embodiments, the distance M can be adjusted by rotating the hand wheel 213. In some embodiments, the distance M is 2 cm. In some embodiments, the distance M is 3 cm. In some embodiments, the distance M is 2.3 cm. In some embodiments, the distance M is 2.5 cm. In some embodiments, the distance M is 2.8 cm.

[0043] Please refer to Figure 3 , Figure 3 , and Figure 1 or Figure 2 Structure diagram of the backing roll 10 in other embodiments for diameter adjustment. The dashed line represents the backing roll 110, and the backing roll 110 has a rotation axis 111. The spraying direction can extend to the first position 102 of the backing roll 110.

[0044] InFigure 3 In some embodiments, the diameter of the back roll 110 is greater than the diameter of the back roll 10, the lowest vertical position on the circumferential surface of the back roll 110 coincides with the lowest vertical position on the circumferential surface of the back roll 10, the rotation axis 111 is further not coincident with the rotation axis 11, and the first position 102 is located to the left of the first position 101. Through research by the inventors, it has been found that the degree of paint back splash when using the back roll 110 is greater than the degree of paint back splash when using the back roll 10. Through a large number of experimental tests and research, it has been determined that reducing the diameter of the back roll 10 and keeping the position of the lowest vertical position on the circumferential surface of the back roll 10 unchanged after the diameter is reduced can increase the distance between the jet orifice of the jet head 212 and the first position 101, and thus improve the paint back splash phenomenon. In some embodiments, the diameter of the back roll 10 after the diameter is reduced can be 1460-1480 mm. In some embodiments, the diameter of the back roll 10 after the diameter is reduced can be 1475 mm. In some embodiments, the diameter of the back roll 10 after the diameter is reduced can be 1465 mm. In some embodiments, the diameter of the back roll 10 after the diameter is reduced can be 1462 mm. In some embodiments, the diameter of the back roll 10 after the diameter is reduced can be 1468 mm. In some embodiments, the diameter of the back roll 10 after the diameter is reduced can be 1478 mm. In some embodiments, the diameter of the back roll 10 after the diameter is reduced can be 1473 mm.

[0045] In some embodiments, through research by the inventors, it has been found that the low shear viscosity of the paint is also a factor in the paint back splash phenomenon, and thus the low shear viscosity of the paint can be controlled to achieve the purpose of improving the paint back splash phenomenon. In some embodiments, the low shear viscosity of the paint is 1000-1100 cPs. In some embodiments, the low shear viscosity of the paint is 1900-2000 cPs. During the research, the degree of paint back splash when the low shear viscosity is 1000-1100 cPs is greater than the degree of paint back splash when the low shear viscosity is 1900-2000 cPs. In addition, when the low shear viscosity continues to increase, the paint flowability will become poor due to the excessively high viscosity, causing a coating leakage phenomenon. Thus, the low shear viscosity of the paint should not be increased too much.

[0046] In some embodiments, the low shear viscosity of the coating is 1950 cPs. In some embodiments, the low shear viscosity of the coating is 1920 cPs. In some embodiments, the low shear viscosity of the coating is 1910 cPs. In some embodiments, the low shear viscosity of the coating is 1970 cPs. In some embodiments, the low shear viscosity of the coating is 1980 cPs. In some embodiments, the low shear viscosity of the coating is 1990 cPs. In some embodiments, the low shear viscosity of the coating is 1960 cPs. In some embodiments, the low shear viscosity of the coating is 1940 cPs. In some embodiments, the low shear viscosity of the coating is 1930 cPs.

[0047] In some embodiments, a thickening agent can be added to the coating to adjust the low shear viscosity of the coating. In some embodiments, the thickening agent can be sodium carboxymethyl cellulose (Carboxymethyl Cellulose Sodium Salt, Carboxymethyl Cellulose, CMC, Carboxymethyl, Cellulose Sodium, Sodium salt of Caboxy Methyl Cellulose), of course, other thickening agents can also be used, which can be known to those skilled in the art.

[0048] In some embodiments, the following experiments are performed

[0049]

[0050]

[0051] Based on the above experiments, it can be seen that, on the basis of the blank group one, increasing the thickening agent can make example one, example two, example three, and example four show that with the increase of the thickening agent, the low shear viscosity increases.

[0052] On the basis of the blank group two, increasing the thickening agent can make example five, example six, example seven, and example eight show that with the increase of the thickening agent, the low shear viscosity increases.

[0053] The high shear viscosity of the coating has little effect on the coating splash in the case of close low shear viscosity, and can not be limited.

[0054] Please refer to Figure 4 , Figure 4 is Figure 1A schematic view of the structure of the liquid supply device 22 in the embodiment. The liquid supply device 22 can include a coating supply member 221, a pressure boosting member 222, a filter member 223, a clean water supply member 224, and a waste liquid collection member 225. The filter member 223 can be connected to the coating supply member 221, the pressure boosting member 222, the clean water supply member 224, the waste liquid collection member 225, and the coating head 21 (e.g., the jet head 212), respectively. The coating supply member 221 can deliver coating to the filter member 223, which is filtered and then delivered to the coating head 21 (e.g., the jet head 212) so that the coating head 21 (e.g., the jet head 212) can spray the coating. Since the filter member 223 functions as a filter, the clean water supply member 224 and the waste liquid collection member 225 are needed to clean the filter member 223. The pressure boosting member 222 controls the pressure in the filter member 223. Before cleaning, the coating in the filter member 223 can be discharged into the coating supply member 221 under the action of the pressure boosting member 222. During cleaning, the clean water supply member 224 provides clean water, and the waste liquid generated by cleaning can be discharged into the waste liquid collection member 225. In some embodiments, the end of the filter member 223 connected to the pressure boosting member 222 can be connected to the waste liquid collection member 225, so that the waste liquid in the filter member 223 can be discharged into the waste liquid collection member 225.

[0055] The coating supply member 221 can be used to store coating and can be filtered by the filter member 223 for the coating head 21 (e.g., the jet head 212). In some embodiments, the coating supply member 221 can be a structure that can store liquid, such as a reservoir, a storage bin, or a storage tank. In some embodiments, the coating supply member 221 can also be a coating work station. In some embodiments, the coating supply member 221 can deliver coating under the action of a power device, such as a liquid pump, and the like. Details can be known to those skilled in the art.

[0056] The pressure boosting member 222 can be used to control the pressure in the filter member 223, so as to increase the pressure in the filter member 223 before cleaning, and drive the coating to be discharged into the coating supply member 221. In some embodiments, the pressure boosting member 222 can include a pressure boosting body 2221 and a pressure valve 2222. The pressure boosting body 2221 is connected to the pressure valve 2222. The pressure valve 2222 is connected to the filter member 223, so that the pressure boosting body 2221 is connected to the filter member 223 through the pressure valve 2222. The end of the pressure valve 2222 connected to the filter member 223 is connected to the waste liquid collection member 225. The pressure boosting body 2221 serves as the main component for controlling the pressure in the pressure boosting member 222. In some embodiments, the pressure boosting body 2221 can be an air pressure booster or an air compressor, and the like.

[0057] The filter member 223 can include a plurality of filter assemblies, such as a first filter assembly 226 and a second filter assembly 227. The number of filter assemblies is not limited to those listed herein. The plurality of filter assemblies are arranged such that when one of the filter assemblies is being cleaned, the other filter assemblies can still be in operation to filter the paint and ensure that the coating head 21, such as the jet head 212, is supplied with paint. For example, when the first filter assembly 226 is being cleaned, the second filter assembly 227 filters the paint and ensures that the coating head 21, such as the jet head 212, is supplied with paint. For example, when the second filter assembly 227 is being cleaned, the first filter assembly 226 filters the paint and ensures that the coating head 21, such as the jet head 212, is supplied with paint.

[0058] Each filter assembly, such as the first filter assembly 226 and the second filter assembly 227, can be connected to the paint supply 221, the pressure booster 222, such as the pressure valve 2222, the clean water supply 224, the waste liquid collection 225, and the coating head 21, such as the jet head 212. The paint supply 221 can deliver paint to each filter assembly, such as the first filter assembly 226 and the second filter assembly 227, and deliver the filtered paint to the coating head 21, such as the jet head 212, so that the coating head 21, such as the jet head 212, can spray the paint. The clean water supply 224 and the waste liquid collection 225 cooperate to clean each filter assembly, such as the first filter assembly 226 and the second filter assembly 227. The pressure booster 222 controls the pressure in each filter assembly, such as the first filter assembly 226 and the second filter assembly 227. Before cleaning, the paint in each filter assembly, such as the first filter assembly 226 and the second filter assembly 227, can be discharged into the paint supply 221 under the action of the pressure booster 222.

[0059] Each filter assembly can have the same structure and components, or can have different structures and components. The first filter assembly 226 is described herein as an example, and the second filter assembly 227 can be understood based on the description of the first filter assembly 226, and will not be described again.

[0060] The first filter assembly 226 can include a filter 2260, an exhaust valve 2261, a feeding valve 2262, an inlet valve 2263, a connection valve 2264, a flushing valve 2265, a return valve 2266, a water valve 2267, and a drain valve 2268.

[0061] The filter 2260 is connected with the paint supply 221 via an inlet valve 2263 and an exhaust valve 2261 to communicate via the inlet valve 2263 and the exhaust valve 2261, respectively. The filter 2260 can deliver paint from the filter 2260 via the inlet valve 2263, and during the delivery, gas or paint in the filter 2260 can flow back to the paint supply 221 via the exhaust valve 2261. The amount of paint in the filter 2260 can be controlled via the inlet valve 2263 and the exhaust valve 2261 such that the amount of paint is greater than or equal to a preset amount of paint, and when the amount of paint is greater than or equal to the preset amount of paint, the paint in the filter 2260 is delivered to the coating head 21, such as the jet head 212. In some embodiments, the preset amount of paint can be the amount of paint delivered from the paint supply 221 to the filter 2260 via the inlet valve 2263 within a first time. In some embodiments, the first time is greater than or equal to 20 s. In some embodiments, the first time is 20 s. In some embodiments, the first time is 25 s. In some embodiments, the first time is 30 s. In some embodiments, the first time is 40 s. In some embodiments, the preset amount of paint can be the amount of paint to fill the filter 2260.

[0062] The filter 2260 is connected with the coating head 21, such as the jet head 212, via a feeding valve 2262 to communicate via the feeding valve 2262 such that the paint in the filter 2260 is delivered to the coating head 21, such as the jet head 212, via the feeding valve 2262.

[0063] The filter 2260 is connected with a flushing valve 2265, and the flushing valve 2265 is connected with the paint supply 221 via a return valve 2266 to drain the paint in the filter 2260 into the paint supply 221 via the flushing valve 2265 and the return valve 2266 to achieve paint recovery during cleaning.

[0064] The flushing valve 2265 can be connected with a water supply 224 via a water valve 2267 to connect the filter 2260 with the water supply 224 via the flushing valve 2265 and the water valve 2267 to drain water into the filter 2260 via the flushing valve 2265 and the water valve 2267 to achieve cleaning.

[0065] The flushing valve 2265 is connected with a waste collection 225 via a drain valve 2268 to connect the filter 2260 with the waste collection 225 via the flushing valve 2265 and the drain valve 2268 to drain liquid in the pipeline into the waste collection 225 before and after cleaning.

[0066] The filter 2260 is connected with the booster 222, such as the pressure valve 2222, through a connection valve 2264, so that the booster 222, such as the booster body 2221, is connected with the filter 2260 through the pressure valve 2222, the connection valve 2264, and the filter 2260, thereby controlling the pressure in the filter 2260, driving the paint in the filter 2260 to be discharged from the flushing valve 2265 and the back material valve 2266 into the paint supply 221, and realizing paint recovery.

[0067] In some embodiments, the filter 2260 is connected with the waste liquid collection 225 through the connection valve 2264, so that the liquid in the filter 2260 is discharged into the waste liquid collection 225 during cleaning. In some embodiments, in order to realize the multiplexing of the connection valve 2264, the waste liquid collection 225 is connected with a blowdown valve 2251, which is connected between the booster 222, such as the pressure valve 2222, and the connection valve 2264, so that one end of the booster 222, such as the pressure valve 2222, connected with the connection valve 2264 is connected with the blowdown valve 2251, and one end of the blowdown valve 2251 connected with the booster 222, such as the pressure valve 2222, is connected with the connection valve 2264.

[0068] In some embodiments, the pore size of the filter screen in the filter 2260 is 125 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 130 μm. According to the inventor's research, in the actual process of paper web coating, when one filter assembly is cleaned and other filter assemblies continue to work, increasing the pore size of the filter screen in the filter 2260 to be cleaned can weaken the pressure fluctuation of the paint in the coating head 21, such as the jet head 212. For example, the pressure fluctuation of the paint with a pore size of 130 μm is weaker than that with a pore size of 120 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 130-170 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 140 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 150 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 160 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 145 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 155 μm. In some embodiments, the pore size of the filter screen in the filter 2260 is 150 μm.

[0069] In some embodiments, please refer to Figure 5 , Figure 5 The following is a comparison chart of the pressure fluctuation of the paint in the coating head 21, such as the jet head 212, in some embodiments of the present application. The pore size of the filter screen in the filter 2260 on the left side of the chart is 125 μm. The pore size of the filter screen in the filter 2260 on the left side of the chart is 150 μm.

[0070] In the left side of the figure, when the feeding valve 2262 is not closed, the paint pressure in the coating head 21, such as the spray head 212, is maintained at about 64.2 kPa, when the feeding valve 2262 is closed, the paint pressure in the coating head 21, such as the spray head 212, is reduced to 62.1 kPa, when the feeding valve 2262 is opened, the paint pressure in the coating head 21, such as the spray head 212, is increased to 66.9 kPa, and then stabilized at 64.2 kPa. The difference between the fluctuations before and after is 4.8 kPa (= 66.9 kPa - 62.1 kPa).

[0071] In the right side of the figure, when the feeding valve 2262 is not closed, the paint pressure in the coating head 21, such as the spray head 212, is maintained at more than 64.2 kPa, when the feeding valve 2262 is closed, the paint pressure in the coating head 21, such as the spray head 212, is reduced to 64.2 kPa, when the feeding valve 2262 is opened, the paint pressure in the coating head 21, such as the spray head 212, is increased to 66.9 kPa, and then stabilized at more than 64.2 kPa. The difference between the fluctuations before and after is 2.7 kPa (= 66.9 kPa - 64.2 kPa).

[0072] In Figure 5 , the influence of the pore size specification of the filter screen of the filter 2260 on the paint pressure in the coating head 21, such as the spray head 212, is weakened, and the pressure fluctuation is significantly reduced, and the improvement in paint back-splashing is more obvious. Furthermore, when the filter 2260 is cleaned, the degree of paint back-splashing can be reduced.

[0073] In some embodiments, the steps of cleaning the filter assembly are as shown in the following table:

[0074]

[0075] The replenishment time after cleaning the filter 2260 is adjusted to the first time, so that after the filter 2260 is replenished, the normal feeding of the coating head 21, such as the spray head 212, is restored, avoiding the situation that the filter 2260 is not sufficiently replenished when the feeding valve 2262 is opened, causing paint backflow to the filter 2260, resulting in fluctuations in the paint pressure in the coating head 21, such as the spray head 212, causing the phenomenon of paint back-splashing.

[0076] Please refer to Figure 6 and Figure 7 , Figure 6 for the schematic diagram of paint back-splashing in some embodiments of the present application. Figure 7 for the schematic diagram of the improvement of the phenomenon of paint back-splashing. It can be seen that the effect of improving the phenomenon of paint back-splashing is obvious. On this basis, the beneficial effects are: the phenomenon of paint back-splashing is improved, and the degradation of coating defects caused by paint back-splashing is significantly reduced after the improvement, and the workload of the on-site operator is also reduced.

[0077] In some embodiments, the process for improving paint splashing is shown in the table below:

[0078]

[0079] The specific adjustments are as follows:

[0080] 1. In July 2022, the included angle β was tested from 25° to 20°. After the engineering department made technical modifications to the equipment, it was tested again from 20° to 16° in August of the same year. At the same time as the included angle β was adjusted, the distance M was also adjusted on site.

[0081] 2. In September 2022, the back roller was replaced for testing (back roller diameter changed from 1501 to 1477 mm);

[0082] 3. In October 2022, the low-shear viscosity of the coating increased from 1080 to 1915 cps;

[0083] 4. In November 2022, the adjustment test was conducted immediately, changing the time from 5 to 30 seconds.

[0084] 5. In December 2022, the filter screen pore size changed from 125 to 150 μm.

[0085] As can be seen, after the above adjustments and tests in December 2022, the paint splattering problem has been completely resolved.

[0086] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and there may be other division methods in actual implementation. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0087] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0088] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0089] The above merely describes the embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, which is made according to the content of the present application specification and drawings, is also included in the patent protection scope of the present application.

Claims

1. A spray coating mechanism, characterized in that, include: A back roller, used to support the paper web, has its rotation axis parallel to the horizontal plane; A spray head, located below the back roll, sprays coating material in the spraying direction toward the side closest to the back roll, and cooperates with the back roll to coat the paper web. The extension line of the spraying direction intersects the circumferential surface of the back roll at a first position. The back roll is configured to increase the distance between the spray nozzle of the spray head and the first position by reducing its diameter and keeping the position of the lowest vertical position on the circumferential surface of the back roll unchanged after the diameter reduction. The spray head is also configured to increase the distance between the spray nozzle of the spray head and the first position by reducing the angle between the spraying direction and the horizontal plane. as well as A liquid supply device for storing the coating material, connected to the spray head, for delivering the coating material to the spray head; The back roller is used to support the paper web on the side near or away from the spray head; the diameter of the back roller after diameter reduction is 1460-1480mm; the angle between the spray direction and the horizontal plane after reduction is 14-20°; the low shear viscosity of the coating is 1900-2000cPs; the distance between the spray nozzle of the spray head and the first position is 1.5-3.5cm. The liquid supply device includes: A paint supply unit for storing the paint; Multiple filter elements are provided, each of which is connected to the paint supply unit and the spray head, so that the paint supply unit delivers the paint to the spray head through the filter element. The amount of paint in the filter element that delivers the paint to the spray head is greater than or equal to a preset amount of paint, which is the amount of paint delivered to the filter element by the paint supply unit within a first time period of greater than or equal to 20 seconds. The pore size of the filter screen in the filter element is 130-170 μm.

2. The spray coating mechanism according to claim 1, characterized in that, The liquid supply device further includes: A clean water supply component is connected to the filter component; A waste liquid collection component, connected to the filter element, is used in conjunction with the clean water supply component to clean the filter element; and A pressurizing component is connected to the filter component.

3. The spray coating mechanism according to claim 2, characterized in that, The filter element is connected to the paint supply element by an inlet valve and an exhaust valve, respectively, so that they can communicate through the inlet valve and the exhaust valve. The filter element is connected to the spray head by a feeding valve, so that they can communicate through the feeding valve. The filter element is connected to a flushing valve. The flushing valve is connected to the paint supply element by a return valve, so that the filter element and the paint supply element can be connected through the flushing valve and the return valve. The flushing valve is connected to the clean water supply element by a water valve, so that the filter element and the clean water supply element can be connected through the flushing valve and the water valve. The flushing valve is connected to the waste liquid collection element by a drain valve, so that the filter element and the waste liquid collection element can be connected through the flushing valve and the drain valve.

4. The spray coating mechanism according to claim 3, characterized in that, The pressurizing component includes a pressurizing body and a pressure valve. The pressurizing body is connected to the pressure valve. A connecting valve is connected between the pressure valve and the filter element so that the filter element and the pressurizing component are connected through the pressure valve and the connecting valve. One end of the connecting valve is connected to the waste liquid collection element.

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