JPH06262117A - Nozzle coater type coating device - Google Patents

Abstract

PURPOSE:To provide the nozzle coater type coating device which uniformly, stably and continuously coat a band-shaped material to be coated with a coating liquid such as paint without being affected by the nonuniformity in supply of a means for supplying the coating liquid to a coating head, etc. CONSTITUTION:This nozzle coater type coating device is constituted to continuously coat the 'traveling band-shaped material 2' with the coating liquid by the nozzle coater type coating head 21 to which the coating liquid is continuously supplied from the means for supplying the coating liquid such as coating liquid tank 7. The above coating device is provided with the nozzle coater type coating heads 21 installed with revolving shafts 23 (inscribed with ruggedness on surfaces at need) for extruding the coating liquid at one point or plural points of a coating liquid passage or coating accumulating part 22 in the device. The coating liquid is fluidized and uniformized and is extruded from the nozzle tips by revolving the revolving shafts 23, by which the uniformity of the coating film is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nozzle coater type continuous coating apparatus for continuously and uniformly applying a coating liquid (paint or the like) to a strip material such as a steel plate.

[0002]

2. Description of the Related Art In recent years, as an apparatus for continuously applying a coating liquid such as a paint to a belt-shaped material such as a metal plate, a synthetic resin film, or a paper, for example, Japanese Patent Application Laid-Open No. 2-56275 discloses "Extrusion-type coating". Called the head,
Further, in Japanese Patent Application Laid-Open No. 2-152574, a "nozzle coater type coating device", which is called a "lip coater type coating head" for flowing out a coating liquid from a slot opening portion for coating, has been noticed. There is.

Of these, the coating head disclosed in Japanese Patent Laid-Open No. 56275/1990, as shown in FIG. 4, is used for a strip-shaped material (workpiece) 2 which is supported by a backup roll 1 and runs. It is one of the very basic nozzle coater type coating heads which are arranged so as to face it from below. Generally, a pocket portion 4 is formed inside the coating head 3, and a pocket portion 4 is formed through the pocket portion 5. The coating liquid flowing out from the slot opening 6 is supplied to the pocket portion 4.

The pocket 4 has a substantially circular cross section, and is in the width direction of the coating head 3 (that is, the width direction of the strip 2).
A kind of liquid reservoir formed to have almost the same length (the effective length is usually set to be equal to or slightly longer than the coating width) and is provided for the purpose of uniformly coating the coating liquid. Is. The slot portion 5 formed continuously with the pocket portion 4 serves as a flow path for the coating liquid as described above, and its length in the width direction is substantially the same as that of the pocket portion 4.

Then, when the pocket 4 of the coating head 3 is filled with the coating liquid from the coating liquid supply means through the pipe or the like, the coating liquid rises in the slot portion 5 due to the liquid pressure at the time of filling, and from the slot opening 6. It flows out and is applied onto the strip 2.

Here, in the coating apparatus disclosed in Japanese Patent Laid-Open No. 2-56275, the coating liquid is supplied to the coating head 3 through the route shown in FIG. That is, it is a path through which the coating liquid is caused to flow from the coating liquid tank 7 to the supply pipe by the pump 8 and directly supplied to the pocket portion 4 of the coating head 3 through the filter 9.

On the other hand, the coating head disclosed in Japanese Patent Laid-Open Publication No. 2-152574 is a coating head as shown in FIG.
In addition to the first liquid reservoir 11 inside 10, a second liquid reservoir 12 is provided at the tip.

During the operation of applying the coating liquid, the coating liquid is pumped from the coating liquid tank 7 to the pump 8 as shown in the explanatory diagram of the coating liquid supply path and the coating liquid supply amount control system in FIG.
Flow into the supply pipe with the first liquid reservoir of the coating head 10.
At the same time as supplying directly to 11, the pressure of the coating liquid in the second liquid reservoir 12 is measured by a pressure measuring sensor-13, and the measured value is taken into a calculation / control device 14 to supply the coating liquid to the pump 8. Is controlled. That is, the pump 8 is controlled according to the difference between the measured value of the coating liquid pressure in the second liquid reservoir 12 and the reference pressure, and the supply amount of the coating liquid is adjusted to obtain a uniform coating film thickness. is there.

However, as is clear from the above description, in the conventional nozzle coater type coating apparatus, the coating liquid supplied to the coating head is pushed out from the slot opening by the direct action of the pressure applied by the coating liquid supply pump. The coating form is applied on the object to be coated (strip). Therefore, minute fluctuations in the pressure of the coating liquid due to pulsation of the pump affect the coating film thickness on the object to be coated. The problem of fluctuations was pointed out.

Further, the coating liquid for the coating head is first supplied to the liquid reservoir from one end of the head, and is sent in the nozzle width direction through the liquid reservoir, so that the coating liquid is supplied by pressure loss due to flow. It was also pointed out that the amount becomes uneven in the width direction of the article to be coated (strip).

In view of the above, the object of the present invention is to apply a coating liquid such as paint to a belt-shaped article without being affected by non-uniform supply of the coating liquid supply means to the coating head. Nozzle core that enables continuous coating evenly and stably
It is to provide a type coating device.

[0012]

The present invention has been completed on the basis of the results of studies made by the present inventors, etc., who were earnestly conducted to achieve the above-mentioned object. A "nozzle coater type coating apparatus" is provided. Is equipped with a nozzle coater type coating head having a rotating shaft for pushing out the coating liquid at one or a plurality of locations inside the coating liquid passage or the coating liquid reservoir. The main feature is that it allows continuous coating of coating films. "

That is, according to the present invention, a "nozzle core" in which the coating liquid is continuously supplied from a coating liquid supply means such as a coating liquid tank.
In a nozzle coater type coating device for continuously applying the coating liquid to the "running strip-shaped material" by a "type coating head",
A rotary shaft that rotates so as to push the coating liquid toward the tip of the nozzle is provided in the coating liquid passage in the coating head or the coating liquid reservoir, and by rotating this shaft, the coating liquid is made to flow and pushed out from the nozzle tip. The present invention is intended to improve the uniformity of the film, and the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic explanatory view showing an example of a nozzle coater type coating apparatus according to the present invention. This coating apparatus, like a normal nozzle coater type coating apparatus, is a belt-shaped material (workpiece) 2 supported by a backup roll 1 and traveling.
The nozzle head portion 21 is arranged so as to face the surface of the
Pocket portion (coating liquid reservoir portion) 22 inside the nozzle head portion
A rotary shaft 23 for pushing out the coating liquid is attached to this. Reference numeral 24 in the drawing is a motor for driving the rotary shaft.
The pocket 22 is connected to the coating liquid tank 7 via the pump 8 by the coating liquid supply pipe.

Further, the pocket portion 22 is provided with a coating liquid pressurizing portion 25 whose flow passage cross-sectional area gradually decreases along the rotation direction of the coating liquid pushing rotary shaft 23. The coating liquid wound around the liquid-extruding rotary shaft 23 is pressurized by the "wedge effect" and is pushed out to the tip of the nozzle.

As described above, the rotary shaft for pushing out the coating liquid
Since 23 is for rotating the shaft and the frictional force between the coating liquid and causing the coating liquid to flow so as to be pushed out toward the tip of the nozzle, in order to make its action more effective, It is preferable to change the surface properties of the rotating shaft by, for example, engraving appropriate irregularities (grooves or the like) on the surface according to the physical properties of the coating liquid.

A groove 26 extending over the entire nozzle width direction is provided at the tip of the nozzle, and a plurality of adjusting holding bolts 27 for pressing the slot wall defined by the groove toward the slot side are arranged at equal intervals in the nozzle width direction. It is installed so that the gap at the nozzle tip (slot opening gap) can be adjusted in the width direction.

Further, at a position downstream of the nozzle head portion 21 in the running direction of the band-shaped material, a film thickness meter 28 (for example, β-ray thickness meter or infrared ray) for measuring the coating film thickness of the coating liquid applied to the band-shaped material 2 is provided. Thickness meter) is installed. The coating film thickness is controlled by measuring the coating film thickness formed on the belt-shaped material 2 with a film thickness meter 28, and controlling the rotation speed of the paint extrusion shaft driving motor 5 according to this value. Controlled by 29. Further, the supply of the coating liquid to the pocket portion 22 of the nozzle head is also performed while the operation of the pump 8 is controlled by the control computer 29.

[0019]

In the nozzle coater type coating apparatus according to the present invention described above, the coating liquid such as paint is sent from the coating liquid tank 7 to the pocket 22 of the nozzle head through the pump 8, which rotates here. It is wound around the rotating shaft 23 for pushing out the coating liquid, and the shear flow is excited to form a uniform flow in the rotating direction. As described above, the minute fluctuations in the coating liquid pressure due to the pulsation of the pump 8 are canceled by the shearing action of the rotating shaft 23 for pushing out the coating liquid, and the shearing action also corrects the nonuniformity of the coating liquid flow in the nozzle width direction. Then, a uniform coating liquid flow is discharged from the tip of the nozzle.

In the apparatus according to this example, as described above, the pocket portion 22 is provided with the coating liquid pressurizing portion 25 whose flow passage cross-sectional area gradually decreases along the rotation direction of the rotating shaft 23. Therefore, not only is the flow of the coating liquid, which has been wound around the rotating shaft 23 for pushing the coating liquid pushed into the coating liquid pressurizing unit 25, sheared and made uniform, but is also added by the “wedge effect” of the coating liquid pressurizing unit 25. Since the pressure is sent to the tip of the nozzle, its uniformizing effect is further amplified, and a more uniform coating liquid flow is extruded onto the surface of the strip 2. Therefore, a coating film having an extremely uniform film thickness can be formed.

At this time, since the magnitude of the shear applied to the coating liquid depends on the peripheral speed of the rotating shaft 23 for pushing the coating liquid, if this is properly controlled, the uniformity of the coating liquid flow rate in the width direction is further enhanced. The accuracy will be guaranteed.

By the way, it becomes difficult for the "high viscosity coating liquid" and "the coating liquid having a strong non-Newtonian property in which the viscosity is remarkably reduced in the high shear region" to be caught by the rotary shaft. However, in this case, as shown in FIG. 2, a plurality of coating solution pushing rotary shafts 23, 23 'are installed in parallel to form the coating solution pressurizing section 25 at a plurality of places, and the surface texture of the rotating shaft is adjusted. Instead, by controlling the friction between the coating liquid and the shaft, the coating liquid can be sufficiently fed and desired coating can be performed.

Although an example in which the strip-shaped material 2 supported by the backup roll 1 is applied is shown here, according to the device of the present invention, the strip-shaped material 2 that is traveling with a proper tension applied thereto is backed up. It goes without saying that the coating liquid can be applied without any of the following.

Next, the effects of the present invention will be described with reference to specific test examples.

[Test example]

<Test Example 1> A coating apparatus as shown in FIG. 1 as an example of the present invention and a coating apparatus as shown in FIG. 4 as a conventional example (type in which paint is directly extruded from the tip of a nozzle by a pressure pump for coating) ) Was used to perform a coating test of a paint on a steel plate having a width of 1000 mm and a thickness of 0.5 mm.

At this time, each nozzle has a nozzle (slot) width of 1100 mm and a nozzle tip (slot) gap: 5
A coating having a thickness of 0 μm was used, the distance between the steel plate surface and the tip of the nozzle was adjusted to 100 μm, and the coating film thickness was variously changed.

The diameter of the "rotating shaft for pushing out the coating liquid" attached inside the nozzle head of the coating apparatus used in the present invention was 15 mm. Further, as the coating material, a high-molecular polyester coating material was used, and the viscosity was adjusted to 1 Pa · s and the surface tension was adjusted to 30 dyn / cm.

Then, "the distribution of variations in coating film thickness in the width direction and the line (longitudinal) direction of the steel sheet" was compared between the present invention example and the conventional example. The results are shown in Table 1.

[0028]

[Table 1]

[0029] As apparent from the results shown in Table 1, for each desired film thickness, in the present invention example was suppressed on the average variation in both directions about ¹ / _2-1 / ₄ as compared with the prior art It was confirmed that the effect of improving the uniformity of the coating film thickness by the device of the present invention is very large.

<Test Example 2> The coating apparatus used as an example of the present invention has a "rotating shaft for pushing out the coating liquid 2" as shown in FIG.
One that has a nozzle head that is provided (the diameter of the rotating shaft is
10 mm, 14 mm) "and that the applied coating had a high viscosity (50 Pa · s), a coating test was conducted under the same conditions as in Test Example 1, and the present invention example and the conventional example were tested. "Dispersion distribution of coating thickness in width direction and line (longitudinal) direction of steel sheet" was compared. The results are shown in Table 2.

[0031]

[Table 2]

[0032] From the results shown in Table 2, for each desired film thickness, in the present invention examples it was confirmed that may suppressed to about _^1/3 the average variation in both directions as compared with the conventional example.

<Test Example 3> The rotating shaft for pushing out the coating liquid of the coating apparatus used as the example of the present invention was "a pitch of 1 mm and a depth of 0.5 mm and a diameter of 10 mm as shown in FIG. 3".
And that the applied coating was a coating having a high non-Newtonian property, a coating test was conducted under the same conditions as in Test Example 1, and in the present invention example and the conventional example, "width direction of steel sheet" And the variation distribution of the coating film thickness in the line (longitudinal) direction "were compared.

As a result, even if a coating material having a high non-newton property is used, various coating film thicknesses can be obtained by applying a rotary shaft for extruding the coating liquid in which concave and convex grooves are engraved. contrast, in the present invention examples it was confirmed that may suppressed to about _^1/3 the average variation in both directions as compared with the conventional example.

[0035]

[Summary of Effects] As described above, according to the present invention, the influence of the coating film defect generation factors such as the pulsation of the pump in the supply of the coating liquid and the non-uniform flow rate in the nozzle width direction is suppressed as much as possible, and the high quality is achieved. It is possible to provide a coating apparatus capable of forming a coating film in a stable manner.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram according to an embodiment of a coating apparatus of the present invention.

FIG. 2 is a schematic explanatory view according to another embodiment of the coating apparatus of the present invention.

FIG. 3 is an explanatory diagram related to an example of a rotating shaft for pushing out a coating liquid applied to the coating apparatus of the present invention.

FIG. 4 is a schematic explanatory view of a coating head in a conventional nozzle coater type coating device.

5 is an explanatory view of a coating liquid supply path to the coating head shown in FIG.

FIG. 6 is a schematic explanatory view of a coating head according to another example of a conventional nozzle coater type coating apparatus.

FIG. 7 is an explanatory diagram relating to a coating liquid supply path and a coating liquid supply amount control system for the coating head shown in FIG.

[Explanation of symbols]

 1 Backup roll 2 Band-shaped material (workpiece) 3 Application head 4 Pocket part 5 Slot part 6 Slot opening 7 Application liquid tank 8 Pump 9 Filter 10 Application head 11 First liquid reservoir 12 Second liquid reservoir 13 Pressure measurement Sensor-14 Calculation / control device 21 Nozzle head 22 Pocket 23 Rotating shaft for pushing out coating liquid 23 'Rotating shaft for pushing out coating liquid 24 Rotating shaft drive motor 25 Coating liquid pressurizing portion 26 Groove 27 Adjusting holding bolt 28 Thickness gauge 29 Control computer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenichi Yanagi 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries Ltd. Hiroshima Research Laboratory

Claims (2)

[Claims] 1. A nozzle coater type coating head provided with a rotary shaft for pushing out a coating liquid at one or a plurality of locations inside a coating liquid passage or a coating liquid reservoir. -Tape coating equipment. 2. A nozzle coater type coating apparatus according to claim 1, wherein a rotary shaft for pushing out the coating liquid, which is attached to the coating liquid passage or the coating liquid reservoir, has irregularities on the surface. .