JPH0539680U - Coating equipment - Google Patents

Abstract

(57) [Summary] [Purpose] When a coating liquid is applied to a web, a high quality coating film is obtained using a non-contact type coating liquid nozzle. [Structure] Web 2 made of paper, steel plate, plastic sheet, etc.
In a device for applying a liquid coating liquid such as a paint or a photosensitizer to the surface of the coating liquid using a nozzle or the like, a means 12 for detecting the film thickness of the coating liquid film 3, and the detection value and the film thickness data previously input. Means for comparing and calculating the coating liquid nozzle 5 based on the calculation result.
The rotary air jet nozzle 11 for controlling the jet angle and / or the jet air amount of the air nozzle 6 provided on the upstream side of the above is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 INDUSTRIAL APPLICABILITY The present invention is applied to a steel plate coating process in an iron-making machine, a paper coater in a paper-making machine, and the like, and is a coating device that applies a liquid coating liquid to a material to be coated (hereinafter referred to as a web) such as paper, steel plate, or plastic It is about.

[0002]

[Prior Art]

 In the conventional coating process on the surface of a steel sheet, a method has been adopted in which a coating liquid is held by a coating roll, pressure-bonded to a running material to be coated, and the coating liquid is applied. However, the present inventors proposed a non-contact coating method in Japanese Patent Application No. 1-20244 in order to improve the coating quality. FIG. 7 shows a cross-sectional view of a conventional non-contact coating method, in which an air nozzle 6 is attached to the back surface of the coating liquid nozzle 5, which is supported by a backing roll 1 and rotates. The air layer 7 entrained in the web 2 traveling together with the web 2 is blocked by an air flow 8 blown backward from the tip 6a of the air jet nozzle 6 in the traveling direction of the web 2. Further, in reality, the space 10 formed by the coating liquid film 3 jetted from the coating liquid jet nozzle 5'at the tip of the coating liquid nozzle 5 and the air flow 8 jetted from the air nozzle 6 is a decompression space, Air is prevented from remaining (mixing) in the liquid 3 ', and stable coating on the web 2 (high-quality coating with no coating defects on the coating surface) is achieved. Further, for the coating liquid film 3, the excess coating liquid is scraped off by the blade 4, the coating amount is adjusted, and the coating film is smoothed to form the coating layer 9. As described above, according to the conventional apparatus in FIG. 7, there is no mixing of impurities falling from the surrounding environment at the time of coating, and it is possible to prevent the mixing of bubbles in the coating liquid film 3 even in the case of high-speed coating, which is better than the conventional method. A stable coating film can be formed.

Further, FIG. 8 shows an example of a coating width defining device in a conventional coating device. The coating liquid is discharged from a coating liquid nozzle 5 onto a web 2 wound around a backing roll 1 and conveyed. In an apparatus for forming a coating width on the web 2 by transferring the coating liquid film 3, when the axial width of the backing roll 1 of the web 2 becomes narrow, the coating layer to be formed on the web 2 When the width of the backing roll in the axial direction is to be narrowed, the coating liquid film 3 discharged from the coating liquid nozzle 5 is a non-application area on the surface of the web 2 (both ends of the web in the backing roll axial direction). ), And the surface of the backing roll 1 (the area where the web is not wound) must be prevented from being contaminated by being attached. In such a case, conventionally, the discharge port of the coating liquid nozzle 5 and the surface of the web 2 or the backing roll 1 are prevented so that the coating liquid film 3 discharged from the coating liquid nozzle 5 does not adhere to the coating unnecessary area. Before the jet flow of the coating liquid film 3 discharged from the coating liquid nozzle 5 by inserting the side seal plate 20 into the area corresponding to the unnecessary coating area between and before reaching the surface of the web 2 or the backing roll 1. A mechanism that was blocked by the side seal plate 20 was used.

Further, FIG. 9 shows an example of another conventional coating apparatus, in which a coating liquid film discharged from a slit formed between the coating liquid nozzles 5 a and 5 b on the surface of the moving web 2. In this apparatus, an entrained air boundary layer 21 is formed on the surface of the web 2 as the web 2 moves. That is, the entrained air boundary layer 21 is sandwiched between the coating liquid film 3 and the surface of the web 2 which have flowed down at the position where the coating liquid film 3 comes into contact with the surface of the web 2, and the surface of the web 2 Air bubbles 22 may be formed between the top and the layer of the coating liquid film 3. When the viscosity and the surface tension of the coating liquid film 3 are low, the air bubbles 22 may burst to generate coating defects 23, which may significantly reduce the coating quality. In order to prevent the coating failure due to the web-entrained air boundary layer 21 as described above, in the conventional apparatus shown in FIG. 9, in the vicinity of the upstream side in the web moving direction at the position where the coating liquid film 3 and the surface of the web 2 contact each other, The rigid plate 24 was arranged close to the surface of the web 2.

[0005]

[Problems to be solved by the device]

 Recently, customers' demands for coating machines have been accelerating, and the demands for coating quality such as cosmetic coatings have become more and more complicated and sophisticated. As a result, the physical properties of the coating liquid have diversified, and it has become necessary to give due consideration to the coating film thickness accuracy and uniformity. In this case, if there is a contact part between the equipment and the web 2 in the coating part structure, there will be inconveniences such as an increase in replacement frequency due to wear of members, an increase in maintenance costs, and instability of coating quality due to the use of worn parts. Occurs. Therefore, the non-contact coating method has a great effect on solving the problem. In the non-contact coating method, as shown in FIG. 7, the coating liquid 3'is uniformly sprayed in the width direction of the web 2 by the coating liquid nozzle 5 by pressurizing the coating liquid. The method of removing the wake air as described in No. 0244 is a good means, but recently, higher quality coating is required while coping with the speeding up of the apparatus. Therefore, the realization of a coating device with high responsiveness is an issue in consideration of the complicated coating conditions.

Further, in the case of the conventional apparatus shown in FIG. 8, since the jet of the coating liquid film 3 discharged from the coating liquid nozzle 5 hits the side seal plate 20, the side seal plate 20 is coated with the coating liquid. Pollute with. Therefore, maintenance such as cleaning of the side seal plate 20 is required. Further, when the gap between the discharge port of the coating liquid nozzle 5 and the web 2 or the backing roll 1 is narrow, there is a point that the side seal plate 20 cannot be inserted into the gap portion, and it can be inserted. However, since the side seal plate 20 comes into contact with the surface of the web 2 or the backing roll 1, problems such as damage to the web 2 or damage to the surface of the backing roll 1 may occur.

Further, in the conventional apparatus shown in FIG. 9, since the rigid plate 24 is slightly separated from the surface of the web 2, the web 2 having the fastest flow velocity in a part of the entrained air boundary layer 21 on the surface of the web 2 is used. The air boundary layer 21 ′ near the surface of the sheet passes under the rigid plate 24. Further, since there is a distance between the rigid plate 24 and the position where the coating liquid film 3 is in contact with the surface of the web 2, the entrained air boundary layer on the surface of the web 2 again occurs again during this time. For these reasons, even after the rigid plate 24 for removing entrained air is arranged, the layer of the coating liquid film 3 formed on the surface of the web is disturbed by the entrained air boundary layer 21 on the surface of the web 2. However, there was a risk that the degree of improvement in coating quality would be low. The present invention has been proposed in order to solve the above conventional problems.

[0008]

[Means for Solving the Problems]

 For this reason, the present invention provides a means for detecting the film thickness of a coating liquid film in an apparatus for applying a liquid coating liquid such as paint or photosensitizer onto the surface of a web such as paper, steel plate or plastic sheet by means of a nozzle or the like. A means for comparing and calculating the same detection value and the previously input film thickness data, and means for controlling the ejection angle and / or the ejection air amount of the air nozzle provided on the upstream side of the coating liquid nozzle based on the calculation result Which is used as a means for solving problems. Further, the present invention is an apparatus for applying a liquid coating liquid such as paint or photosensitizer to the surface of a web such as paper, steel plate or plastic sheet by means of a nozzle or the like, and the web surface near the position where the web and the coating liquid come into contact with each other. An air nozzle that blows air is provided near the end in the width direction to regulate the coating width by blocking the transfer of the coating liquid in the relevant portion.This is the means for solving the problem. It is a thing. Further, the present invention is an apparatus for applying a liquid coating liquid such as paint or photosensitizer to the surface of a web such as paper, steel plate, plastic sheet, etc. by means of a nozzle or the like, and the flow path discharge of the nozzle for discharging the coating liquid. An elastic flat plate in contact with the web is provided on the upstream side of the tip of the outlet, and this is a means for solving the problem.

[0009]

[Action]

 In order to form a stable coating liquid film according to the coating conditions, it is a simple and effective measure to use a nozzle that can arbitrarily change the air jet direction and change the landing angle of the jet air on the web surface. Is. As a result, when it is necessary to change the distance between the coating liquid nozzle and the web, the angle formed by the coating liquid nozzle with the web, etc. in actual operation, or there is a change in the coating liquid flow rate, web speed, etc. In such cases as well, by changing the ejection angle of the air ejection nozzle (and the ejection air amount in some cases), it is possible to create an optimal state for stabilizing the formed liquid film. By adopting a structure in which the air ejection angle from the air ejection nozzle can be adjusted as described above, the angle of air collision with the web and the size of the decompression space formed with the coating liquid film change, and the material to be treated is changed. It is possible to minimize the amount of wake air, or to easily control the degree of decompression in the decompression space or the stability of decompression to an appropriate value. As a result, a stable coating film can be formed, so that the condition of the coating film can be detected and the air ejection angle of the nozzle can be optimally controlled.

According to the second aspect of the present invention, the air jet ejected from the two-dimensional air nozzle flows as a two-dimensional sheet-like air jet along the surface of the uncoated portion of the web and the surface of the backing roll. , Enter the position where the coating liquid contacts the surface of the web or backing roll. The air jet blown into this portion forms an air layer so as to be sandwiched between the non-coated portion of the web and the surface of the backing roll and the coating liquid film discharged from the coating liquid nozzle. If the thickness and flow velocity of this air layer to the jet of the coating liquid film are sufficient, the jet of the coating liquid film is bent in the downstream direction of the air jet, and then separated from the web or backing roll surface by the action of gravity. Therefore, it is impossible to reach the surface of the web or the backing roll by breaking the air layer. Therefore, the coating liquid does not adhere to the surface of the web or the surface of the backing roll in the region where the air layer is present.

According to the third aspect of the present invention, the elastic flat plate is disposed so as to continuously contact the surface of the web at the discharge port of the coating liquid film, and the coating liquid film discharged from the nozzle is Since the elastic flat plate flows down along the back side in the web running direction, the entrained air boundary layer on the surface of the web is blocked by the elastic flat plate, and the free surface of the coating liquid film and the coating liquid film reach the surface of the web. You cannot enter the contact position. Further, since the coating liquid film flows along the back surface of the elastic flat plate in the web running direction, the position between the position where the elastic flat plate contacts the web surface and the position where the coating liquid liquid contacts the web surface. No space is formed in the space, and no recurrence of the entrained air boundary layer occurs. Therefore, a stable coating liquid film is formed on the surface of the web, and the coating quality is improved.

[0012]

【Example】

 Hereinafter, the present invention will be described with reference to an embodiment of the drawings, and FIGS. 1 and 2 show a first embodiment of the present invention. In the present invention, the same parts as the conventional one will be described using the same reference numerals. In the figure, 1 is a backing roll, 2 is a web, 3 is a coating liquid film, 5 is a coating liquid nozzle, and 6 is an air nozzle, which are the same as those shown in FIG. 7. Further, 11 is a rotary air jet nozzle, 12 is a coating film thickness measuring instrument, 13 is a control unit, 14 is a control valve, and 15 is a drive device. FIG. 2 shows a detailed view of the main part (the tip of the coating liquid nozzle) in FIG. In FIG. 2, the coating liquid is sprayed from the coating liquid jet nozzle 5 ′ forming the tip of the coating liquid nozzle 5 at an appropriate angle α and a distance d (normally 0. 2-1 mm) is ejected. The web 2 (shown as a flat plate in the figure, but may be along the curvature of the backing roll 1) is running in the direction of the arrow. At the tip of the air nozzle 6 which is connected to the rear side of the coating liquid nozzle 5, there is provided a rotary air jet slit nozzle 11 capable of changing the jet direction of air with respect to the web 2. .. Although not shown, the rotary air jet nozzle 11 has shaft portions at both ends, and the air jet direction can be set to an appropriate angle by using a driving device 15 such as a small motor. When coating an iron plate, a dry coating film is generally applied to a thickness of 5 to 50 μm, and the coating speed is about 30 to 150 m / min. When the nozzle of the present invention shown in FIG. 2 is used, the amount of coating liquid required for coating is evenly jetted and supplied in the width direction of the web 2 from the coating liquid jet nozzle 5'for coating. It is not necessary to smooth the coating film, especially with a blade. In coating, first, the angle of the coating liquid nozzle 5 and the gap between the web 2 are set so that the amount of air is appropriate for the physical properties of the coating liquid and the coating conditions, and the air jet angle is set to the air nozzle 6 The formula air ejection nozzle 11 is adjusted to set the conditions such that coating defects and unevenness of the coating liquid film thickness do not occur. However, in the end, all conditions including the optimum amount of air blown for coating film formation are set more easily than before, a stable coated surface is formed, and high quality products can be obtained. Here, the coating film quality is obtained by scanning a coating film thickness measuring device (which can be used with an existing measuring device such as an infrared spectroscopic absorption method) 12 installed behind the coating liquid nozzle 5 as shown in FIG. The coating film formation state is determined by detecting the film thickness, and the nozzle condition (nozzle angle and / or jet air amount) is controlled to an optimum value by a preset correlation function with the nozzle angle and air amount. The control unit 13 processes the signal of the measuring instrument 12 and controls a drive device 15 including a valve 14 for changing the amount of air jetted from the air jet nozzle 11 and a servomotor for changing the angle of the air jet nozzle 11. There is.

Next, the second embodiment of FIGS. 3, 4 and 5 will be described. On the web 2 which is wound around the backing roll 1 and conveyed, an arbitrary position on the circumference of the backing roll 1 is provided. At, the coating liquid 3'is sprayed from the coating liquid nozzle 5. On the other hand, the air nozzle 6 is moved to the coating liquid nozzle 5 so that the coating liquid film 3 discharged from the coating liquid nozzle 5 blows an air jet toward the vicinity of the position in contact with the surface of the web 2 or the backing roll 1. The web 1 is arranged either upstream (FIG. 4) or downstream (FIG. 3) in the traveling direction. The position of the air nozzle 6 is such that when the coating liquid film 3 discharged from the coating liquid nozzle 5 is bent by the air jet and then falls downward due to gravity, the web 2 or the backing roll 1 is Mount it in a position where it will be difficult to re-contact the surface. The conditions under which the coating liquid film 3 discharged from the coating liquid nozzle 5 does not contact the surface of the web 2 or the backing roll 1 and the air jet from the air nozzle 6 sufficiently exerts the coating width regulating function , The coating liquid jet flow velocity is 1.0 m / sec, and the coating liquid jet thickness is 0. 3 mm, when the coating liquid jet angle is about 60 ° with respect to the web running direction tangent at the position where the coating liquid normally contacts, the air jet flow velocity is 10 m / sec, the air jet thickness is 5 mm, and the air jet angle is The air jet may be set under the condition that the tangent to the web at the position where the coating liquid contacts the web are parallel to each other.

As described above, the coating liquid film 3 that has not adhered to the surface of the web 2 or the backing roll 1 flows downward due to the action of gravity. Further, a part of such a coating liquid becomes a mist and is scattered downstream of the air jet due to the fluid friction generated between the coating liquid and the air jet. Further, in order to collect the coating liquid that has not adhered to the surface of the web 2 or the backing roll 1, a pan 17 is arranged in a direction in which the coating liquid 3'flows or scatters. The coating liquid 3'collected in the pan 17 is recirculated by an appropriate known means and is again discharged from the coating liquid nozzle 5. The arrangement of the coating liquid nozzle 5 and the air nozzle 6 in FIGS. 3 and 4 is such that the ejection direction is upside down, and the air nozzle 6 is arranged downstream in the web traveling direction in FIG. Although they are arranged in the flow direction, in any case, the coating liquid discharge direction and the air jet direction are the same direction. By blowing air into the wedge-shaped space formed between the coating liquid jet and the web surface, the air pressure acting on the coating liquid jet is increased, and the coating liquid and the web surface come into contact with each other. It is to prevent things effectively. Also, this is not limited to the case where the angle formed by the discharge direction of the coating liquid and the web surface is a right angle or close to a right angle, and the coating liquid that has been removed by the blown air and has not adhered to the web surface moves vertically downward due to gravity. When falling, an air nozzle may be provided so that the air is not reattached to the surface of the web 2 and the air is ejected in a direction in which it can be efficiently collected. FIG. 5 shows the positional relationship between the coating liquid nozzle 5, the web 2 and the air nozzle 6. The coating width is controlled by moving the air nozzle 6 in the width direction of the web 2 by rotating the pinion gear 18 'connected to the rack 18 connected to the coating liquid nozzle 5 by an electric motor or the like. It has become.

Next, referring to FIG. 6, a third embodiment of the present invention will be described. Of the tips of the lips 5a and 5b that serve as the discharge ports of the coating liquid film 3, the nozzle 5b that is located on the upstream side in the running direction of the web 2 is described. The elastic flat plate 19 is arranged at the tip so that the coating liquid continuously drops on the coating liquid flow path surface 5b 'of the nozzle 5b. The elastic flat plate 19 is arranged under the following conditions. Shall be satisfied. That is, the tip of the lip 5b has a sharp edge so that no step is formed at the joint between the coating liquid flow surface 5b 'of the lip 5b and the coating liquid flow lower surface 19' on the elastic flat plate 19. The length of the elastic flat plate 19 is such that after the elastic flat plate 19 is bonded to the outer surface of the lip 5b by an appropriate bonding method such as an adhesive, the tip of the elastic flat plate 19 comes into contact with the surface of the web 2 at least, or The length should be longer than that. Furthermore, the elastic flat plate 19 follows changes in the surface shape of the web 2 (unevenness, etc.), but for foreign matter such as dust on the surface of the web 2, this causes the coating liquid film 3 and the surface of the web 2 to be different from each other. Use a material that has a rigidity that can be excluded so as not to penetrate into the contact area and that has a high smoothness on the lower surface of the coating liquid film 3 (for example, synthetic paper such as ceramic coated paper or Teflon sheet).

When the elastic flat plate 19 is arranged so as to satisfy the above conditions, the entrained air boundary layer developed on the surface of the web 2 as the web 2 moves causes the coating liquid film 3 and the surface of the web 2 to come into contact with each other. It collides with the elastic flat plate 19 on the upstream side of the moving position in the web moving direction. At this time, the rigidity of the elastic flat plate 19 depends on the dynamic pressure of the entrained air boundary layer and the air layer penetrating into the wedge-shaped space formed between the elastic flat plate 19 and the surface of the web 2 according to the fluid lubrication theory. The elastic flat plate 19 completely blocks the entrained air boundary layer on the surface of the web 2 because it is not deformed by the fluid pressure generated. On the other hand, since the coating liquid film 3 flows down along the surface corresponding to the back surface of the elastic flat plate 19 with which the entrained air boundary layer collides, the entrained air boundary layer on the surface of the web 2 causes The coating liquid film 3 reaches the surface of the web 2 without hindering the flow of the coating liquid film 3 and forms a stable coating liquid film 3 on the surface of the web 2. When ceramic coated paper is used for the elastic flat plate 19, the elastic flat plate 19 does not easily wear even when it comes into contact with the web 2, has excellent durability, and provides stable coating quality for a long time. In the embodiment shown in FIG. 6, the coating speed, the shape and size of the elastic flat plate 19, the distance between the object to be coated and the nozzle, etc. are not particularly limited. The effect of removing the air flow accompanied by the web has been confirmed at a processing speed of 300 m / min, an elastic flat plate width of 500 mm, a length of 10 mm, a thickness of 0.2 mm, and a distance of 2.0 mm from the workpiece to the nozzle.

[0017]

[Effect of the device]

 As described in detail above, according to the present invention, a high quality coating can be realized by providing a non-contact type coating liquid nozzle that can easily respond to changes in coating conditions. That is, the effective removal of the wake air from the web, the uniformization of the coating liquid film by stabilizing the depressurized space, and the highly accurate coating tolerance can be achieved by a simple operation operation. In addition, since the stable state of film coating can be controlled online, the product quality can be stabilized and the economic loss due to defective coating is reduced. Furthermore, since the nozzle part is downsized, the coating part structure is simple and easy to maintain. Further, in the present invention, the air nozzle is provided so that the transfer of the coating liquid at the relevant portion is obstructed to regulate the coating width, so that the side seal plate which has been used conventionally becomes unnecessary, and the cleaning is required. It is possible to omit such work. It can also be used when the coating liquid nozzle and the surface of the web or backing roll are close to each other, which makes it difficult to insert the conventional side seal plate. Further, in the present invention, since the elastic flat plate which is in contact with the web is provided on the upstream side of the tip of the flow path outlet, the coating trouble caused by the entrained air boundary layer generated on the surface of the web can be eliminated, and the stability and the stability can be improved. We can supply quality coatings. Further, foreign matter such as dust existing on the web surface is removed, and the web surface can be cleaned.

[Brief description of drawings]

FIG. 1 is a side view of a coating apparatus showing a first embodiment of the present invention.

FIG. 2 is a detailed view of a main part in FIG.

FIG. 3 is a side sectional view of a coating apparatus showing a second embodiment of the present invention.

FIG. 4 is a side cross-sectional view of FIG. 3 when the spray directions of the coating liquid nozzle and the air nozzle are upside down.

FIG. 5 is a front view of FIG.

FIG. 6 is a side sectional view of a coating apparatus showing a third embodiment of the present invention.

FIG. 7 is a side sectional view showing an example of a conventional coating apparatus.

FIG. 8 is a side sectional view showing another example of a conventional coating apparatus.

FIG. 9 is a side cross-sectional view of a coating apparatus different from each of the conventional examples.

[Explanation of symbols]

 1 Backing Roll 2 Web 3 Coating Liquid Film 3'Coating Liquid 5 Coating Liquid Nozzle 5'Coating Liquid Jet Nozzle 6 Air Nozzle 11 Rotary Air Jet Nozzle 12 Coating Thickness Meter 13 Control Unit 14 Control Valve 15 Drive 17 Pan 18 Rack 18 'Pinion 19 Elastic Flat Plate

Claims (3)

[Scope of utility model registration request] 1. A device for applying a liquid coating liquid such as paint or photosensitizer to the surface of a web such as paper, steel plate, plastic sheet, etc. by means of a nozzle or the like, and means for detecting the film thickness of the coating liquid film, Means for comparing and calculating the same detection value and previously input film thickness data, and means for controlling the ejection angle and / or the ejection air amount of the air nozzle provided on the upstream side of the coating liquid nozzle based on the computation result A coating device characterized in that 2. An apparatus for applying a liquid coating liquid such as paint or photosensitizer to the surface of a web such as paper, steel plate, plastic sheet, etc. by means of a nozzle or the like, in the vicinity of the position where the web and the coating liquid contact each other. A coating apparatus, wherein an air nozzle for blowing air is provided in the vicinity of an end portion in the width direction, and the coating width is regulated by inhibiting transfer of the coating liquid in the corresponding portion. 3. In a device for applying a liquid coating liquid such as paint or photosensitizer to the surface of a web such as paper, steel plate, plastic sheet, etc. by means of a nozzle or the like, the tip of the flow passage outlet of the nozzle for discharging the coating liquid. An elastic flat plate in contact with the web is provided on the upstream side of the coating device.