JP4836372B2 - Coating method and rod coater - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating method and a rod coater that apply a coating agent having a constant film thickness to the surface of a web that is continuously conveyed along a predetermined conveying line, and particularly when a coating agent to which a filler is added is applied. Is preferred.
[0002]
[Prior art]
When coating films of various coating agents are formed on the surface of webs that are continuously conveyed, such as roll paper, fabrics, plastic films, and metal foils, coatings such as gravure coaters, roll knife coaters, lip coaters, and rod coaters A device is used. Among these coating apparatuses, the rod coater includes an application system for supplying an excessive coating agent to the web and a metering system for scraping off the excessive coating agent from the web to form a predetermined coating film thickness. . That is, after excessively supplying the coating agent to the surface of the web that is continuously conveyed and applying it, the coating was applied excessively by the measuring rod that is rotating forward or backward with respect to the direction of web conveyance. The coating agent is scraped off from the surface of the web, and a coating film of the coating agent having a predetermined thickness is formed on the surface of the web.
[0003]
In a measuring rod used in such a rod coater, a wire-wound rod in which a wire is tightly wound around the outer periphery of a core bar is frequently used when the coating film thickness of the coating agent needs to be relatively thin relative to the web. It is possible to cope with a relatively wide coating film thickness by adjusting the solid content concentration and viscosity of the coating agent. Moreover, the coating film thickness of the coating agent on the web can be increased as the wire diameter is increased, and conversely, the coating thickness of the coating agent on the web can be decreased as the wire diameter is decreased.
[0004]
[Problems to be solved by the invention]
In a conventional rod coater using a winding rod as a measuring rod, a space with a substantially triangular cross section sandwiched between the surface of the web on which the coating agent is applied and the wire adjacent to the winding rod, that is, the cell is very Because of its small size, when continuous operation is performed over a long period of time, foreign substances such as dust, resin gel or filler particles are gradually accumulated in the above-mentioned cell portion, causing clogging. There has been a problem that the film thickness is not uniform and a streak pattern is formed, that is, streak defects frequently occur and the yield of the coated product is lowered. In addition, since such streak defects tend to occur more frequently as the web conveyance speed increases, it is necessary to form a coating film with a good quality of uniform thickness on the web in a high-speed conveyance state. Was extremely difficult.
[0005]
In addition, when such a muscle defect occurs, the clogging foreign matter causing the muscle defect is allowed to pass by temporarily stopping or reversing the measuring rod, or the web The conveyance line must be stopped and replaced with a new measuring rod, and the measuring rod that has been clogged removed from the line needs to be cleaned, which reduces the manufacturing yield.
[0006]
In particular, when applying a coating agent to which a filler is added to the web, if a wire rod with a wire diameter of 0.4 mm or less is used, the above-mentioned streak defects due to clogging frequently occur. Therefore, it is almost impossible to control the coating thickness to an arbitrary coating thickness, and the coating agent cannot be thinly coated with good quality.
[0007]
OBJECT OF THE INVENTION
An object of the present invention is to provide a coating method and a rod coater that can be applied to a constant film thickness while suppressing generation of a streak pattern due to clogging of a measuring rod, even with a coating agent to which a filler is added. is there.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, a step of excessively applying a coating agent to a surface of a web that is continuously conveyed along a predetermined conveying line, and a part of the coating agent applied to the surface of the web are performed. A coating method having a step of scraping off by a rotating measuring rod and making the film thickness of the coating agent applied to the surface of the web constant, and applying a predetermined vibration along the rotating direction to the measuring rod It is characterized by comprising steps.
[0009]
According to a second aspect of the present invention, there is provided an application roll for excessively applying a coating agent to a surface of a web that is continuously conveyed along a predetermined conveying line, and a coating agent applied to the surface of the web. A measuring rod for scraping a part to make the film thickness constant, a rod driving means for driving and rotating the measuring rod, and a rotational vibration for applying a predetermined vibration along the rotation direction to the measuring rod The rod coater is characterized by comprising an imparting means.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the coating method according to the first aspect of the present invention, the coating agent may be a filler added, and the measuring rod is a wire wound rod in which a wire is wound around a core metal, and the wire diameter of the wire is 0. It may be in the range of 0.05 to 1.5 mm.
[0011]
Steel with a diameter of 3 to 25 mm, stainless steel, brass, etc. can be used as the core, and metal wires such as piano wire, stainless steel wire, brass wire, tungsten wire, nylon filament, polyethylene terephthalate (Tetron) : Toray Industries, Inc.) Synthetic resin filaments such as filaments can be used, and it is also effective to wind the wire around the core metal in multiple strips or multiple windings.
[0012]
Instead of the wire wound rod, it is also possible to use an engraving rod or a rolling rod in which grooves having a predetermined depth are formed on the outer peripheral surface at a predetermined pitch.
[0013]
When the frequency along the rotation direction of the measuring rod is higher than 3000 Hz, the effect of the present invention cannot be obtained sufficiently. On the contrary, when the frequency is lower than 30 Hz, a streak pattern is generated on the surface of the coating film. Therefore, the frequency is preferably in the range of 30 to 3000 Hz.
[0014]
In the rod coater according to the second embodiment of the present invention, when the frequency applied to the measuring rod by the rotational vibration applying means is higher than 3000 Hz, the effect of the present invention cannot be obtained sufficiently, and conversely, the frequency is lower than 30 Hz. Since a streak pattern may be generated on the surface of the coating film, the frequency is preferably in the range of 30 to 3000 Hz.
[0015]
The rotational vibration applying means may be an exciter, or the rod driving means may be a stepping motor, and this stepping motor may also serve as the rotational vibration applying means.
[0016]
【Example】
Embodiments of the rod coater according to the present invention will be described in detail with reference to FIGS. 1 to 4, but the present invention is not limited to such embodiments, and further combinations thereof, It can be applied to other techniques to be included in the inventive concepts described in the scope.
[0017]
The schematic structure of the rod coater in the first embodiment is shown in FIG. 1, the appearance of the metering system is shown in FIG. 2, and the portion of the measuring rod is enlarged and shown in a broken state in FIG. That is, in FIG. 1, an application roller 11 that rotates and rotates clockwise in FIG. 1 by a roller drive motor (not shown) is disposed immediately below the web W that is horizontally conveyed so as to pass from the left side to the right side. The upper end of the web W is in contact with the back surface over the entire width of the web W. The lower end portion of the application roller 11 is located in the supply pan 12 to which the coating agent C is supplied and is immersed in the coating agent C stored in the supply pan 12. In this way, the application roller 11 is driven and rotated in synchronization with the conveyance of the web W, so that the coating agent C stored in the supply pan 12 is excessively applied to the entire back surface of the web W. .
[0018]
In the application system in this embodiment, the roll coating method using the application roller 11 is adopted, but the coating agent C is excessively applied to the back surface of the web W by another coating method such as a dip coating method or a fountain coating method. It is also possible. Further, as the coating agent C, an aqueous solution of a polymer compound, an organic solvent liquid, a pigment dispersion, a dye dispersion, an inorganic filler dispersion, a colloidal solution, or the like is used depending on the application, and the physical properties also depend on the application. From a very low viscosity solution of several millipascal seconds to a high viscosity solution of several thousand millipascal seconds can be appropriately selected.
[0019]
The supply pan 12 and the coating agent storage tank 13 for storing the coating agent C replenished to the supply pan 12 are in communication with each other via a supply conduit 14. A supply pump 15 for supplying the coating agent in the tank 13 to the supply pan 12 is interposed. Further, in order to keep the liquid level of the coating agent C stored in the supply pan 12 constant and to remove bubbles floating on the liquid surface of the coating agent C, the supply pan 12 includes a coating agent storage tank 13. An overflow pipe 27 that communicates is provided. The replenishment pump 15 operates in accordance with the supply of the coating agent C from the supply pan 12 to the web W by the application roller 11 so that the excess coating agent C is returned from the overflow pipe 27 to the coating agent storage tank 13. As a result, the liquid level of the coating agent C stored in the supply pan 12 is kept constant.
[0020]
A measuring rod 17 that is driven to rotate counterclockwise in FIG. 1 by a rod drive motor 16 is disposed downstream of the application roller 11 in the conveyance direction of the web W, and further on the opposite side of the measuring rod 17 across the web W. A pair of guide rolls 28 are arranged. The pair of guide rolls 28 are located on the upstream side and the downstream side of the measuring rod 17, and the upper end of the measuring rod 17 stably contacts the back surface of the web W over the entire width of the pair of guide rolls 28. It will be in the state. The measuring rod 17 for regulating the coating agent C excessively applied to the back surface of the web W by the application roller 11 to a predetermined film thickness is a V block protruding upward from the coating agent recovery pan 18 installed below the measuring rod 17. A rod holder 19 having a cross section is supported rotatably. The coating agent recovery pan 18 and the coating agent storage tank 13 communicate with each other via a recovery pipe line 20, so that the coating agent C scraped off from the back surface of the web W by the measuring rod 17 is positioned immediately below the coating agent C. It flows into the coating agent recovery pan 19 and returns to the coating agent storage tank 13 from the recovery pipe 20.
[0021]
The measuring rod 17 of the present embodiment uses a winding rod in which a stainless steel wire 22 having a diameter of 0.05 to 1.5 mm is wound around the outer periphery of a stainless steel core bar 21 having a diameter of 6 mm. As described above, in FIG. 1, the drive rotation is made counterclockwise, but it is also possible to drive the drive rotation clockwise.
[0022]
FIG. 2 shows the appearance of the portion of the metering system in the embodiment of the rod coater according to the present invention. That is, the rod drive motor 16 connected to the measuring rod 17 via the joint 23 is attached to the bracket 25 via the vibrator 26. The vibrator 26 according to the present embodiment mechanically rotates the rod driving motor 16 together with the measuring rod 17 in the forward and backward directions around the axis thereof, thereby applying rotational vibration to the measuring rod 17. Specifically, the exciter 26 is composed of a rotary oscillating type actuator having a structure similar to that of a motor, and the rotor portion to which the rod drive motor 16 is connected by flowing an excitation current has a range of 30 to 3000 Hz. What is necessary is just to carry out rotation rocking | fluctuation with a frequency. Vibration in the circumferential direction on the outer peripheral surface of the measuring rod 17 is 0.5 mm, and more preferably in the range of 0.2 to 0.3 mm, along the direction of rotation of the measuring rod 17. . In this case, as the viscosity of the coating agent C increases, and when the coating agent C such as a pigment dispersion or an inorganic filler dispersion is used, the higher the specific gravity or the amount of additives, the higher the frequency is. It is generally preferred to shift to.
[0023]
In this way, by applying vibration along the rotation direction of the measuring rod 17, even when the coating agent C is applied to the web W over a long period of time, Foreign substances such as fillers and dust that are interposed between the two are scraped off and become difficult to clog. As a result, the occurrence of defects such as streak defects is suppressed with respect to the coating agent C applied to the web W, and the coating agent C can be uniformly and stably applied to the web W.
[0024]
The joint 23 connecting the rod drive motor 16 and the measuring rod 17 can be a bellows type or a coil type having flexibility, but is generated by the vibrator 26. It is preferable to use a rigid structure so that the vibration can be transmitted to the measuring rod 17 as it is without mitigating vibration.
[0025]
Using the above-described rod coater, the web W is continuously conveyed at a rate of 60 meters per minute with a coated paper having a total length of about 5000 m, a width of 1500 mm, and a basis weight of 130 g / m ² . A Newtonian fluid in which an inorganic filler having an average particle size of 5 μm is dispersed as a coating agent applied to coated paper during conveyance of the web W, with a rotational speed set to 80 revolutions per minute and a frequency set to 3000 Hz. Specifically, an application experiment of an organic solvent solution of a polymer compound having a viscosity of about 10 millipascal seconds at 25 ° C. was performed.
[0026]
As a result, no clogging or streak defect occurs until the wire diameter of the wire 22 of the measuring rod 17 is 0.05 mm, the coating agent C can be applied to the web W in a thin and uniform thickness, and the filler Even with the added coating agent C, it was confirmed that the film thickness with respect to the web W could be controlled over a wide range. In addition, the frequency of the measuring rod 17 is set to 50 Hz when the wire diameter of the wire 22 is 1.0 mm, and the frequency is set to 1000 Hz when the wire diameter is 0.4 mm. It was confirmed that no clogging or muscle defect occurred.
[0027]
On the other hand, if the measuring rod 17 is not vibrated in the rotation direction, the wire diameter of the wire 22 of the measuring rod 17 is 0.4 mm, and a streak defect due to clogging occurs, as in this embodiment. It has been found that it is difficult to apply the coating agent C thinly on the web W, and the film thickness of the coating agent C on the web W cannot be controlled over a wide range.
[0028]
In the above-described embodiment, the measuring rod 17 is rotated using the mechanical vibrator 26 and simultaneously vibrated along the rotation direction. However, a pulse motor such as a stepping motor is employed as the rod driving motor 16. This rod drive motor 16 can also serve as the rotational vibration applying means of the present invention.
[0029]
FIG. 4 shows the appearance of the portion of the metering system in another embodiment of the rod coater according to the present invention. Elements having the same functions as those of the previous embodiment are designated by the same reference numerals and are duplicated. The description will be omitted. That is, the rod drive motor 16 of this embodiment coupled to the measuring rod 17 via the joint 23 is fixed via the bracket 25 on the gantry 24 installed along the web W conveyance line. The rod drive motor 16 uses a pulse motor capable of applying a predetermined vibration along the rotation direction of the measuring rod 17, for example, a stepping motor or an AC servo motor as the rotational vibration applying means of the present invention. At the same time as rotating 17, radial vibration having a frequency of 30 to 3000 Hz may be applied to the measuring rod 17. In this case, it is preferable to use a stepping motor having a low control resolution with respect to the rotation angle.
[0030]
Thereby, even when the coating operation of the coating agent C on the web W is performed for a long time due to the rotational vibration of the measuring rod 17 by the rod driving motor 16, it is interposed between the measuring rod 17 that is driven to rotate and the rod holder 19. The foreign material such as filler and dust is scraped off and clogging is less likely to occur, and the occurrence of defects such as streak defects is suppressed with respect to the coating agent C applied to the web W, and the coating agent C is uniformly and stably applied. It is possible to apply to the web W.
[0031]
As the rotational vibration applying means of the present invention for the measuring rod 17, a technique such as electrostriction or magnetostriction is used in addition to the embodiment described above, or an electromagnetic induction type or brush type electrical connection is used as the joint 23. It is also possible to give a predetermined vibration to the measuring rod 17 by adopting.
[0032]
【The invention's effect】
According to the coating method of the present invention, since the metering rod is given a predetermined vibration along the rotation direction, the filler is clogged in the metering rod even when the coating agent to which the filler is added is applied. Can be prevented, and the coating agent can be uniformly and smoothly applied to the surface of the web.
[0033]
Even if a filler is added to the coating agent, a wire wound rod in which a wire with a wire diameter in the range of 0.05 to 1.5 mm is wound around the core can be used without clogging. The coating agent can be uniformly applied to the surface of the web with good smoothness, and the adjustment range of the coating film thickness can be expanded.
[0034]
When the frequency is within the range of 30 to 3000 Hz, the effects of the present invention can be obtained more reliably.
[0035]
According to the rod coater of the present invention, rotation that gives a predetermined vibration along the rotation direction to the measuring rod for scraping off a part of the coating agent applied to the surface of the web to make the film thickness constant. Since vibration imparting means is provided, even when a coating agent with filler added is applied, it is possible to prevent problems such as filler clogging on the measuring rod, and uniform coating agent on the web surface. And can be applied smoothly.
[0036]
When the frequency applied to the measuring rod by the rotational vibration applying means is within the range of 30 to 3000 Hz, the effects of the present invention can be obtained more reliably.
[0037]
When an exciter is used as the rotational vibration applying means, vibration can be controlled easily.
[0038]
When a stepping motor is used as a rod driving means, this stepping motor can be used as a rotational vibration applying means, so the number of parts is reduced, the rod coater is made compact, and it is adapted to various coating work conditions. Any vibration can be easily applied to the metering rod.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing an embodiment of a rod coater according to the present invention.
FIG. 2 is a perspective view showing an appearance of a metering system in the rod coater shown in FIG.
3 is a cutaway front view of a portion of a winding rod that constitutes a main part of a metering system in the embodiment shown in FIG. 2. FIG.
FIG. 4 is a perspective view showing the appearance of a metering system in another embodiment of the rod coater according to the present invention.
[Explanation of symbols]
W Web C Coating Agent 11 Application Roller 12 Supply Pan 13 Coating Agent Storage Tank 14 Supply Pipe 15 Supply Pump 16 Rod Drive Motor 17 Metering Rod 18 Coating Agent Recovery Pan 19 Rod Holder 20 Recovery Pipe 21 Core Bar 22 Wire 23 Joint 24 Base 25 Bracket 26 Exciter 27 Overflow pipe 28 Guide roll

Claims (8)

Applying an excessive amount of coating agent to the surface of the web that is continuously conveyed along a predetermined conveying line; scraping off a portion of the coating agent applied to the surface of the web with a rotating measuring rod; A coating method having a step of making the film thickness of the coating agent applied to the surface of the web constant,
A coating method comprising the step of applying a predetermined vibration along the rotation direction to the measuring rod.   The coating method according to claim 1, wherein the coating agent is added with a filler.   The said measuring rod is a wire wound rod which wound the wire around the metal core, and the wire diameter of the said wire exists in the range of 0.05-1.5 mm, The Claim 1 or Claim 2 characterized by the above-mentioned. Coating method.   The coating method according to any one of claims 1 to 3, wherein a frequency of the vibration is in a range of 30 to 3000 Hz. An application roll for overcoating the coating agent on the surface of the web that is continuously conveyed along a predetermined conveying line;
A measuring rod for scraping off a part of the coating agent applied to the surface of the web and making the film thickness constant;
Rod driving means for driving and rotating the measuring rod;
A rod coater comprising: a rotation vibration applying means for applying a predetermined vibration along the rotation direction to the measuring rod.   The rod coater according to claim 5, wherein the frequency of the vibration applied to the measuring rod by the rotational vibration applying means is in a range of 30 to 3000 Hz.   The rod coater according to claim 5 or 6, wherein the rotational vibration applying means is an exciter.   7. The rod coater according to claim 5, wherein the rod driving means is a stepping motor, and the stepping motor also serves as the rotational vibration applying means.

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