JPH04150970A - Roller curtain coater - Google Patents

Abstract

PURPOSE:To eliminate the irregularity or cutting of a curtain due to the abrasion or damage of a blade and to stably obtain a smooth film for a long time by coating a coating roll and the blade with ceramic. CONSTITUTION:Paint P is supplied to the roll gap between a ceramic coated coating roll 7 and a hard doctor roll 8 from a paint supply pipe 6 to be allowed to fall downwardly along the coating blade 7 and scraped off by the blade B brought into contact with the coating roll 7. The scraped-off paint flows along the stage N of the guide blade 12 provided to a blade stand 9 and separates from the leading end W of the blade 12 to form a paint curtain C which is, in turn, applied to the plate 1 to be painted passing under the blade stand 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to curtain flow coating techniques, particularly to a roller one-type curtain coater. The present invention is applied to coating steel plates, cut plates thereof, or coiled plates.

(Conventional technology) Curtain flow coating technology provides a smooth and beautiful coating surface because the coating is applied in the form of a curtain, so it is not applicable to coating a variety of substrates such as metal plates, plastic films, and paper. There are various methods for this method, one of which is the roller curtain flow coating method. This is disclosed, for example, in Japanese Utility Model Application Publication No. 63-63163. This configuration is explained with reference to FIG. , the paint P is supplied to the roll gap between the coating rubber roll 2 and the metal doctor roll 3, and is discharged downward along the coating rubber roll 2 through the roll gap, and the blade 4 is brought into contact with the coating rubber roll 2. The scraped paint P flows down along the blade 4,
A paint curtain C is formed and applied to the plate 1 to be coated passing below the blade 4. The predetermined curtain thickness at this time is adjusted by the circumferential speed of the coating rubber roll 2 and doctor roll 3 and the gap between the rolls. The doctor knife 5 prevents the paint P supplied between the coating rubber roll 2 and the doctor roll 3 from flowing out in the rotational direction of the doctor roll 3.

Another method is disclosed in Japanese Patent Laid-Open No. 63-7869. This method uses a three-roll type curtain flow coater, and the conventional slit type and overflow type had the problem that paint deposits were generated at the fixed part, causing the curtain to break. In order to improve this, a roll method is used to eliminate the fixed part and prevent the paint from accumulating. One of the features is that by using a hard roll, there is no change in the amount of paint applied due to roll swelling. It becomes.

[Problems to be Solved by the Invention] Conventional roller curtain coaters completely scrape off the paint on the coating rubber roll to form a uniform curtain. A method has been used to adjust the pressing force of the blade using elasticity. Such coating rubber roll 2 is made of materials such as urethane, nitrile rubber, butyl rubber, etc., and is used for materials whose hardness ranges from soft (rubber hardness 25°) to hard (rubber hardness 95°). Ketone-based and ester-based roll materials swell to a greater or lesser extent and the roll gap changes, resulting in problems such as variations in curtain thickness and poor painted appearance.

In order to solve this problem, the present inventors tried a method of using a hard metal roll instead of the coating roll 2, improving the precision of the machining finish of the roll, and appropriately adjusting the pressure force of the blade. By doing so, we were able to suppress fluctuations in the roll gap due to rubber swelling and eliminate defects such as poor curtain thickness and uneven coating. In addition, when the paint P is supported (transferred) on the surface of the hard metal roll (hard chrome plated copper roll), it is necessary that the coating roll surface has sufficient wettability for the paint. I understand. To explain this based on FIG. 4, if the wettability of the coating roll 2 is insufficient, the paint P will slip between the two surfaces of the coating roll and the paint P will not flow down from the gap between the rolls, and the paint curtain C This resulted in the problem that it could no longer be formed.

Furthermore, in order to solve this problem, we used a polished hard ceramic coated roll with a surface roughness of Ra 3 to 5μ instead of the hard metal roll, and appropriately adjusted the pressure of the blade in the same way as described above. By trying this, the paint slip phenomenon due to the wettability of the roll did not occur between the paint and the coating roll surface, but on the other hand, the hardness of the ceramic film caused severe wear and damage to the blade, and the paint on the coating roll surface was scraped off. During this process, uneven scraping occurs, resulting in coating defects such as curtain unevenness and curtain breakage, creating a new problem that significantly impedes long-term coating stability.

In order to eliminate this phenomenon, we investigated various ways to adjust the hard blade of the hard ceramic coated coating roll and the pressing force. However, we found that the motor of the coating roll was overloaded and the coating roll was seriously damaged. The above operation was extremely difficult.

The present invention not only prevents film thickness fluctuations due to swelling of the coating rubber roll, which were problems with conventional roller curtain coaters, and also prevents paint slippage on hard metal rolls, but also prevents the coating from newly forming blades. Eliminate curtain unevenness and curtain breakage caused by wear and damage,
To provide a new roller curtain coater that can stably obtain a smooth coating film without defects for a long time.

[Means for Solving the Problems] The present invention solves these problems by (1) using a coating roll and blade coated with ceramic;
) Making the surface hardness of the coating roll coated with ceramic and the blade approximately the same level (3) Combining the coating roll coated with soft ceramic with a metal blade (4) The surface roughness of the ceramic coating of the coating roll Sao Ra 0.01-2. (5) Use a blade coated with a ceramic coating having a thickness of 0.1 to 5Itwl.

Hereinafter, the present invention will be explained in detail based on the drawings.

The apparatus of the present invention is supplied with paint P as shown in FIG.
In addition, a ceramic coated roll 7 facing a hard doctor roll 8 that can be retracted to adjust the curtain thickness, and a blade mount 9 for mounting a hard blade B brought into contact with the roll below the ceramic coated roll 7 are arranged.
As shown in the figure, the blade B is made of a material that is resilient and hard even after ceramic treatment and has a springback effect.

The ceramic coated roll 7 is a steel roll coated with the ceramic shown in Table 1 by plasma spraying, and the surface of the roll is mirror-finished to a flatness with an average roughness Ra of 0.01 to 2Δn. The blade B that comes into contact with the coating roll 7 is made of steel with a machined finish (■■) L, or hard ceramic or soft ceramic, so as not to damage the part where it contacts the coating roll 7. A dense film is applied by physical vapor deposition (PvD method) or chemical vapor deposition (CVD method), and a mirror finish is obtained by puff polishing. The ceramic material must have good wettability with the paint, and those shown in Table 1 are preferred.

In this case, replacing the brags is easier than replacing the rolls and is cheaper than the cost of processing the rolls, so as long as the replacement is not too frequent and does not significantly impair painting workability, the hardness of the ceramic coating on the rolls should be avoided. On the other hand, materials with a difference in Pinkers hardness of around 100 kg/i2 can also be used.

The hard doctor roll 8 is dammed with a doctor knife 5 made of hard material so that the film thickness does not change due to swelling due to the solvent contained in the paint, and the paint does not get wet or overflow along the doctor roll. , Ceramic-coated rolls made of hard materials with excellent wear resistance (see Table 1) can also be applied. The surface of the roll is preferably mirror-finished in order to prevent uneven thickness of the curtain and the smoothness of the coated surface. Further, FIG. 2 shows an adjustment mechanism of the blade mount 9 for attaching the blade B to the coating roll 7. In FIG. 2, the blade B attached to the blade mount 9 is adjusted by loosening a plurality of screws 10 and moving the blade B up and down with a plurality of screws 11 paired with the screw 10 to adjust the pressing force of the blade B. The lengthwise direction of the coating roll 7 can also be adjusted in the same way, and the parallelism between the coating roll 7 and the blade B can be configured with high precision. Third
As shown in the figure, the shape of the blade B is set so that the blade B is in close contact with the tangent to the longitudinal direction of the coating roll and the curved surface of the roll. We take advantage of the elasticity of materials such as steel, alloy steel, nitrided steel, stainless steel, and stainless steel alloy copper. For example, the blade used in the present invention is made of nitrided steel (such as Swedish steel), which is used to evenly scrape off ink adhering to the gravure roll of a gravure printing machine, and has a thickness T of 50 to 150 p.

The guide blade L/-eye 2 shown in Fig. 2 fixes the blade 8, and has a curved surface so that the falling paint is directed downward smoothly by the stage N, and the paint does not go to the back side of the tip at the tip W. Make an acute angle like this.

(for production) Next, the operation of the present invention will be explained.

In FIGS. 1 and 2, the paint P is supplied from a paint supply vibro to the gap between the ceramic coated coating roll 7 and the hard doctor roll 8, and the paint is allowed to flow downward along the coating roll 7. Scrape with blade B that is in contact with 7. The scraped paint is removed from the guide plate 12 provided on the blade mount 9.
The paint flows along the stage N, forms a paint curtain C away from the tip W, and is applied to the plate 1 to be coated passing below the blade mount. Pressure adjustment between the blade B and the coating roll 7 is performed as follows. Adjust the screws 10 and 11 of the blade mount 9 in advance so that the blade B can come into close contact with the coating roll 7, and then set the coating roll 7 at a circumferential speed of 100, for example.
While rotating for m7 minutes, the blade B is momentarily brought into contact with the surface of the coating roll to scrape off the paint, and then the screw of the blade mount 9 is finely adjusted to prevent local unevenness on the surface of the coating roll. It should be noted that the device is equipped with an air crimping mechanism (not shown).

In this way, in the case of the ceramic coated coating roll and the ceramic coated blade B or the soft ceramic coated coating roll, even if the metal blade B is used, it is possible to spread the paint evenly and stably for a long period of time, and the slip phenomenon of the paint can be prevented. Painting unevenness due to curtain breakage and blade wear was eliminated, and extremely excellent effects were obtained.

Preliminary tests were carried out using blade and roll wear tests to investigate the lifespan of the blades. The rubbing abrasion test used various prototype rolls and blades, and a device in which a constant load was applied to the rolls and blades, and the rolls rotated, and conditions such as wear and damage on the blade edge were judged based on the following evaluation criteria. . (See Figures 5 and 6) Evaluation Criteria If the thickness of the coating on the blade exceeds 6 pm, it is not preferable because a dense ceramic film cannot be formed on the metal surface. Further, if the thickness is less than 0.5μ, the frequency of blade replacement becomes high, which impedes productivity.

Although an example of the ceramic coating S is shown in FIG. 3, it may be coated only on the cutting edge of the blade.

[Examples] Examples of the present invention will be described below. In the apparatus shown in Fig. 1, the coating roll includes carbon-based, alumina-based, zirconia-based, titania-based, chromium-based,
Using commercially available raw materials such as tungsten and ceramics mixed with additives, 1
After applying a film of 00 to 500 μm, the material was polished and finished as described above. Furthermore, as shown in Fig. 3, a commercially available Swedish foil was used for the blade B, and an ion beam in the PVD method or CVD method, which can coat thin objects with ceramic of the same type or approximately the same hardness as the roll, was used. Rating is done from 1 to 5 to take advantage of the elasticity of the blade.
A coating S as dense as μ was applied and combined with the roll (the present invention). And as shown in Table 1, a roll coated with soft ceramic and a metal blade were combined (
present invention).

We then conducted tests on combinations of hard chrome plated rolls and metal blades (comparative examples) and hard ceramic coated rolls and metal blades (comparative examples).
The results are shown in Table 1 and Figures 5 and 6.

An example of the coating conditions used in the above test will be described. The paint is a solvent-based polyester paint with a non-volatile content of 4, which has a different viscosity.
Viscosity 50 seconds/25°C at 0-t% (Ford Cup #4
) and non-volatile content of 45-t%, viscosity 100 seconds/25°C (
Two types of Ford Cup #4) were used, and the peripheral speed of the rolls was 60 m/min for the coating roll and 1.7 m/min for the doctor roll.
The conditions were set as 0.25 m+ and a roll gap of 0.25 m+. At that time, the plate passing speed was 60 m/min to obtain a dry coating thickness of about 20 layers with a curtain flow rate of about 60 cc/nf. The material and shape of the blade were Swedish steel (nitriding steel) with a hardness of 580 to 600 kg/an2 (Vickers hardness) and T=70.

When a normal hard chrome plated roll and a metal blade are combined as in Comparative Example 1, the abrasion resistance of the blade is the first.
As shown in the table, it was excellent because the hardness of the materials was approximately the same level, but on the other hand, although two types of paint with different viscosity were used, there was a slip phenomenon between the rolls that was thought to be caused by wetting with the paint. This caused curtain unevenness and curtain breakage.

This is because the physical and chemical surface conditions (frontal activation energy, porosity, etc.) of the hard chrome plated surface are different from those of the ceramic surface.

On the other hand, when a hard ceramic coated roll and a metal blade were combined as in Comparative Example 2, the rolls had good wettability, were less likely to slip between the rolls, and did not cause curtain unevenness or curtain breakage. However, the hard ceramic coated roll used had a Vickers hardness of approximately 900 kg/mm, and the hardness of the metal blade was HV.
Since the weight was extremely low at 580 to 600 kg/B2, blade wear was extremely bad.

On the other hand, when a metal roll and a metal blade coated with ceramic of the same type or approximately the same hardness are combined as in Examples 1 to 28 of the present invention, the results are shown in Table 1 and Figure 5. Blade wear was significantly suppressed, and no curtain unevenness or curtain breakage occurred, resulting in no practical problems.

In addition, when a soft ceramic coated roll and a metal blade are combined as in Examples 29 to 36, as shown in Table 1 and FIG. 5, the metal blade is made of carbon steel, nitrided mesh, or alloy steel, If necessary, a hardening heat treatment was applied to make the blade approximately the same hardness as the roll, and the abrasion resistance of the blade was very good, and no curtain unevenness or curtain breakage occurred. As shown in Fig. 6, the surface roughness of the coating roll affects the abrasion of the blade, so it is approximately 2μ.
The following flatness is required, and the results showed that the smoother the surface, the better the abrasion resistance. From this result, the smaller the surface roughness, the better in order to improve the abrasion resistance.

However, finishing to an average roughness Ra of 0.01 or less increases the polishing cost too much, which impairs the economic effect (effects of the invention) In the present invention, the coating roll is a ceramic coated roll, and the metal blade is By coating with ceramic of approximately the same hardness, and by applying an elastic metal blade of approximately the same hardness to the coating roll coated with soft ceramic, the coating, which is a feature of the conventional roller curtain method, is improved. It maintains the smoothness of the surface, and there is no change in film thickness due to long-term swelling of the roll, and it also eliminates the phenomenon of paint slipping, and does not cause coating defects due to curtain unevenness or curtain breakage due to blade wear, and provides stable coating quality. I was able to secure it. This contributes to increased work efficiency and improved product yield, and is expected to have a significant economic effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing the device of the present invention, FIG. 2 is a schematic side view of the blade mount of the present invention, FIG. 3 is an enlarged view of the blade of the present invention, and FIG. 4 is a conventional device. A schematic side view, Fig. 5 is a diagram showing the relationship between the wear life of the plate shown in the example and the comparative example, and Fig. 6 is a diagram showing the relationship between the roll surface roughness and the abrasion of the blade shown in the example and the comparative example. It is a diagram. 1... Board to be coated (cut board, coil), 2... Coating rubber roll, 3... Doctor roll, 4... Blade, 5...
...Doctor knife, 6...Paint supply pipe, 7
...Hard coating roll, 8...Hard doctor roll, 9...Blade mount, 10, 11...Screw, 12...Guide plate.

Claims (1)

[Scope of Claims] 1. A roller curtain coater configured to collect paint between a coating roll and a doctor roll, scrape off the paint flowing down along the coating roll with a blade, and cause the paint to flow down in a curtain shape. A roller curtain coater characterized by having a roll and blade coated with ceramic. 2. The roller curtain coater according to claim 1, wherein the coating roll and the blade have substantially the same surface hardness. 3. In a roller curtain coater configured to collect paint between a coating roll and a doctor roll, scrape off the paint flowing down along the coating roll with a blade, and make it flow down in a curtain shape, the coating roll is coated with hard ceramic. A roller curtain coater characterized in that the blade is a metal blade. 4. The roller curtain coater according to claim 1, 2 or 3, wherein the ceramic coating of the coating roll has a surface roughness Ra of 0.01 to 2.0 μm. 5. The thickness of the ceramic coating on the blade is 0.5 to 5 μm.
The roller curtain coater according to claim 1 or 2, wherein the coating temperature is within the range of .