JP2667033B2 - Roller curtain coating method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a roller curtain coating method.

The roller curtain coating method supplies a paint between a paint roll and a doctor roll, whose axes are arranged in parallel at a predetermined roll surface interval, and paints that are carried on the paint roll surface and discharged downward from between the two rolls. This is a method of scraping off with a doctor blade provided in contact with the lower part of the coating roll, freely falling downward in a curtain shape, and coating an object to be coated with the free-falling curtain of the coating material by passing the object under both the rolls. The coating roll is a roll for supporting a coating material on a rotating roll surface and continuously supplying the coating material to a coating curtain via a doctor blade. The doctor roll is usually rotating in the opposite direction to the paint roll, and is a roll that pulls back the paint carried on the paint roll and limits the amount of paint that is carried downward from between the two rolls to a predetermined amount. is there. The amount of paint supplied to the paint curtain is adjusted mainly by the interval between the two rolls and the rotational peripheral speed.

Roller curtain coating, like other curtain coating methods such as slit type and overflow type, can eliminate virtually no paint loss compared to brush coating, spray coating, dipping coating, etc. It has excellent advantages such as extremely large capacity and very good finish of the painted surface.In addition, compared to other curtain painting methods, it can take a lot of adjustment factors such as the amount of paint supply, so it can be applied to small quantity and many kinds of painting. It has the advantage of being able to respond quickly.

In recent years, in particular, home appliances, office equipment, etc. have become extremely diversified in accordance with their uses or customer demands, and the materials used for these, such as pre-coated steel sheets, are also materials, dimensions (thickness, width), coloring, coating, etc. Since the types of films have been diversified according to each request, the superiority of the roller curtain coating method, which can relatively easily cope with the production of small lots of various types, is attracting more attention.

[Conventional technology]

In the roller curtain coating method, for example, as disclosed in Japanese Utility Model Laid-Open No. 61-177892 and Japanese Utility Model Laid-Open No. 63-63163, when supplying paint between a coating roll and a doctor roll, The paint was directly supplied between these two rolls to form a paint pool between both rolls.

However, in the above method, the liquid level of the paint pool rises below the paint supply nozzle, or the entire surface of the paint pool undulates, causing a so-called "dancing phenomenon" to cause unevenness of the paint. The present inventor has already proposed, as a method of preventing such coating unevenness, a method of supplying a coating material on a coating roll surface or a doctor roll surface without forming a paint pool ("Roller curtain coating method"). Filed on January 31, 1990).

In the above proposed method, when the paint is supplied on the doctor roll surface and then carried (transferred) on the paint roll surface, the paint roll surface has sufficient wettability to the paint. There is a need. If the wettability is insufficient, a slip phenomenon occurs between the paint and the paint roll surface, and the paint on the doctor roll surface is not sufficiently transferred to the paint roll surface, which eventually causes the paint curtain to break. This slip phenomenon becomes more remarkable as the peripheral speed of the coating roll (strictly speaking, the peripheral speed of the coating roll relative to the peripheral speed of the doctor roll) is increased, and it becomes an obstacle to the controllability of the coating film thickness.

Conventionally, a hard roll such as a stainless steel roll, a ceramic roll, or a chrome-plated steel roll has been used as a coating roll, but the roll surface is mirror-finished in order to be in close contact with the blade of a doctor blade. Such a mirror-finished roll surface has poor wettability to paint, and there is a problem that the paint curtain is likely to be cut due to poor paint transfer from the doctor roll surface.

Further, when unevenness occurs when the paint carried on the surface of the coating roll is scraped off by the doctor blade, a streak of the paint remains on the surface of the coating roll passing through the doctor blade in accordance with the unevenness of the scraping. When the paint roll surface makes a round and receives paint transfer from the doctor roll again, transfer unevenness occurs corresponding to this streak, which causes unevenness in the thickness of the paint curtain, and eventually streaky unevenness in the coating thickness Was causing it.

[Problems to be solved by the invention]

The present invention is a roller that prevents paint curtain breakage due to poor transfer of paint from a doctor roll to a paint roll, prevents the occurrence of streaky paint unevenness, and enables stable high-quality painting even when the paint roll peripheral speed is increased. It is an object to provide a curtain coating method.

[Means for solving the problem]

According to the present invention, according to the present invention, the paint supplied on the doctor roll surface is transferred onto a coating roll surface which is arranged in parallel with the axis at a predetermined roll surface interval, and is carried on the coating roll surface. The paint discharged downward from between the two rolls is scraped off by a doctor blade provided in contact with the lower part of the coating roll, freely dropped downward in a curtain shape, and the object to be coated is passed under the two rolls. In the method of coating with a free-fall curtain, a soft-assisting auxiliary roll is placed in contact with a coating roll surface moving from a doctor blade toward a doctor roll, and the auxiliary roll is rotated reversely with respect to the coating roll. This is achieved by a roller curtain coating method characterized by the following.

(Operation)

The roller curtain coating method of the present invention is a method in which a soft auxiliary roll disposed in contact with a coating roll surface passing through a doctor blade and moving toward a doctor roll is reverse-rotated with respect to the coating roll, so that the doctor Auxiliary roll presses and smoothes the residual streaks of paint remaining on the coating roll surface that has passed through the blade, and forcibly rubs the remaining paint against the coating roll surface with the auxiliary roll to make the coating roll surface uniform with paint. Since it can be wetted, it eliminates the streaky paint unevenness and the breakage of the paint curtain due to the slip phenomenon at the same time.

 Hereinafter, the present invention will be described in more detail with reference to Examples.

〔Example〕

FIG. 1 shows an embodiment of the roller curtain coating method of the present invention.

FIG. 5 shows an example of a roller curtain coating method having the same configuration as that of FIG. 1 except that no auxiliary roll is used for comparison.

In both figures, on the right side of the coating roll 1 is arranged a doctor roll 2 which rotates in reverse with respect to it. Paint T
Is supplied from the supply port t of the paint supply jig 5 onto the roll surface of the doctor roll 2, is transferred to the roll surface of the coating roll 1 at the position Y, is carried on the coating roll 1 surface, moves downward, and The paint curtain 6 is scraped off by a doctor blade 4 provided in contact with the lower portion of the roll 1 and guided downward.
After the free fall, it is applied to the surface of the plate-shaped or band-shaped object 7 traveling below in the direction of arrow S to form a coating film.

Normally, the coating roll 1 and the doctor roll 2 are arranged at a roll surface interval corresponding to the thickness of the paint curtain to be formed, the coating speed, and the like. As the coating roll 1 and the doctor roll 2, hard rolls such as ceramic rolls, stainless steel rolls, and chrome-plated steel rolls are generally used.

In the case of FIG. 5 in which the auxiliary roll is not used, the scraping unevenness P ′ of the paint remaining on the surface of the paint roll 1 that has passed the doctor blade 4 causes the paint transfer from the doctor roll 2 to the paint roll 1 to occur. As a result of being carried over to the position Y where the transfer is performed, uneven transfer, uneven thickness of the paint curtain 6, and final uneven paint thickness (uneven paint unevenness) occur. Furthermore,
Since the paint wets the surface of the paint roll 1 very unevenly in the form of scraping unevenness P ', the transfer from the doctor roll 2 becomes extremely unstable, and the fuel curtain 6 is liable to break.

However, in the example of FIG. 1 using the auxiliary roll according to the present invention, the auxiliary roll 3 is disposed in contact with the surface of the coating roll 1 moving from the doctor blade 4 toward the doctor roll 2. That is, the doctor roll 2 is disposed on the right side of the coating roll 1 and the auxiliary roll 3 of the present invention is disposed on the left side in FIG. The auxiliary roll 3 rotates reversely with respect to the coating roll 1. After all, these three rolls 1,
As shown by arrows R1, R2, and R3, all of 2 and 3 have a relationship in which the neighbors are reverse rotated.

As the auxiliary roll 3, a soft roll such as a rubber roll, a sponge roll, a bristle roll, and a cloth roll is used. Such a soft auxiliary roll 3 is brought into contact with the coating roll surface moving toward the doctor roll 2 from the doctor blade 4 and rotated reversely to scrape the coating roll 1 having passed the doctor blade 4 onto the coating roll 1 surface. The remaining unevenness P is pressed for smoothing. At the same time, since the two rolls are rotated in reverse with each other, the remaining paint is forcibly rubbed against the paint roll 1 so that the paint roll 1 moving from the auxiliary roll 3 toward the doctor roll 2 is uniformly coated with the paint Q. Wet. That is, in FIG. 1, the area a from the contact area Y ′ between the coating roll 1 and the auxiliary roll 3 to the opposing point Y between the coating roll 1 and the doctor roll 2 is uniformly wet with the paint Q, The paint transfer in Y can be performed without any problem.

Furthermore, the contact area Y 'between the auxiliary roll 3 and the coating roll 1
In addition, by supplying a small amount of the same paint as that to be coated, the wetting of the surface of the coating roll 1 moving from the auxiliary roll 1 toward the doctor roll 2 can be further improved.

For example, as shown in FIG. 2, the supply of the paint to the contact area Y 'can be performed in the form of a curtain 11 from a thin slit-like paint supply port 10 disposed immediately above the contact area Y'.

As another method, as shown in FIG. 3, an extruder coater 12 arranged almost in contact with the roll surface of the auxiliary roll 3 is used.
May be supplied in a thin film form onto the roll surface of the auxiliary roll 3 (F in the figure), and may be transferred by pressing against the roll surface of the coating roll 1 in the contact area Y '.

Further, as shown in FIG. 4, a roll having a roll surface made of a soft porous material such as sponge is used as an auxiliary roll 3, and a small amount of paint 14 is applied to the porous roll surface from a paint supply port 13. You may supply by the method of dripping and impregnating.

〔The invention's effect〕

As described above, the roller curtain coating method of the present invention reverses a soft auxiliary roll disposed in contact with a coating roll surface passing through a doctor blade and moving toward a doctor roll with respect to the coating roll. By rotating the coating, the streaks of paint remaining on the coating roll surface that passed through the doctor blade are pressed by the auxiliary roll to smooth it, and the residual paint is forcibly rubbed against the coating roll surface by the auxiliary roll and painted. Since the roll surface can be uniformly wetted with paint, streak-like coating unevenness and paint curtain breakage due to slip phenomenon can be eliminated at the same time, and high quality coating can be performed stably even when the coating roll peripheral speed is increased. .

[Brief description of the drawings]

1 to 4 are side views showing an example of an apparatus for performing a roller curtain coating method using an auxiliary roll according to the present invention, and FIG. 5 is a roller curtain coating method without using an auxiliary roll. It is a side view which shows the comparative example at the time of performing a method. 1: Paint roll, 2: Doctor roll, 3: Auxiliary roll, 4: Doctor blade, 4 ': Doctor knife, 5: Paint supply jig, 6: Paint free fall curtain, 7: Workpiece, 10: Thin Slit-shaped paint supply port, 11: paint supplied in a curtain form from paint supply port 10, 12: extrusion coater, 13: paint supply port, 14: paint dropped from paint supply port 13, P, P ': Uneven scraping (streak-like residual paint) Q: Paint that uniformly wets the roll surface of paint roll 1, R1: paint roll rotation direction, R2: doctor roll rotation direction, R3: auxiliary roll rotation direction, S: The traveling direction of the workpiece, T: paint in the paint supply jig 5, t: paint supply port of the paint supply jig 5.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hideo Kotani 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation Kimitsu Works (72) Inventor Toshimichi Murata 1 Kimitsu, Kimitsu City, Chiba Prefecture New Japan Inside Kimitsu Works, Steel Corporation (72) Inventor Kazuyoshi Inuchi 1, Kimitsu Works, Kimitsu City, Chiba Prefecture Inside Kimitsu Works, Nippon Steel Corporation

Claims (5)

(57) [Claims] 1. A paint supplied on a doctor roll surface is transferred onto a coating roll surface having its axis parallel to the coating roll and arranged at a predetermined roll surface interval. The paint discharged to the paint roll is scraped off by a doctor blade provided in contact with the lower part of the coating roll, falls freely in the shape of a curtain downward, and the object to be coated passes under the above both rolls, thereby painting with the free fall curtain of the paint. Roller coating, wherein a soft auxiliary roll is arranged in contact with a coating roll surface moving from a doctor blade toward a doctor roll, and the auxiliary roll is rotated reversely with respect to the coating roll. Method. 2. The method according to claim 1, wherein a small amount of the coating material used for the coating is supplied also to a contact area between the auxiliary roll and the coating roll. 3. The method according to claim 2, wherein the paint is supplied directly to the contact area from a paint supply port located immediately above the contact area. 4. The method according to claim 2, wherein the paint is supplied to the contact area by supplying a small amount of the paint used for the coating with an extrusion coater onto the roll surface of the auxiliary roll. 5. A paint supply to the contact area by impregnating the porous material portion with a paint used for the coating by using a roll made of a spongy porous material at least on a roll surface as the auxiliary roll. 3. The method according to claim 2, wherein