JPH0745021B2 - Coating equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a roller type coating apparatus for applying a coating material to a metal sheet, for example, a metal sheet for can making.

(Prior Art) As a conventional roller-type coating device for applying paint to a sheet such as a metal sheet for can making, a coating roll having an elastic sleeve such as rubber and a distributor for transferring the paint to the coating roll. A type that has rolls, and both rolls rotate at the same peripheral speed in a forward direction (that is, when one roll rotates in the clockwise direction, the other roll rotates in the counterclockwise direction) Is commonly used.

In the case of this type of coating equipment, the viscosity of the applied coating is high (for example, # 4 Ford cup viscosity of about 60-20
0), or a large coating amount (for example, dry coating thickness of about 6
In the case of ˜15 μm) or the like, a striped uneven pattern called a rib (or flow pattern) is likely to occur in the formed coating film.
This uneven pattern not only spoils the appearance of the product (for example, a metal can) but also causes a problem that the amount of paint used is increased and the production cost is increased.

In addition, if the blank of the metal lid has this uneven pattern,
When the lid is formed, when the blank is made of a relatively thin and hard aluminum alloy plate, there is a problem that wrinkles are likely to occur in the seaming panel (annular panel portion that is raised around the edge of the lid). Since this wrinkle impairs the sheet tightness (wrinkle degree of the cover hook) during double winding, it is necessary to prevent the wrinkle from occurring in order to secure the sealing property.

(Problems to be Solved by the Invention) The present invention provides a so-called rib on the surface of a sheet even when the coating material has a relatively high viscosity and a relatively large coating amount.
An object of the present invention is to provide a roller type metal sheet coating apparatus capable of forming a smooth coating film.

(Means for Solving the Problems) A metal sheet coating apparatus according to the present invention is a fountain roll;
A distributor roll that has a slight gap between the fountain roll and transfers the paint to the coating roll; a coating roll that is in slight contact with the distributor roll through the paint film and has a relatively soft elastic sleeve; And a backup roll facing the coating roll, the surface of each roll other than the coating roll is a metal sheet coating device made of steel, the distributor roll rotates forward relative to the coating roll, and the peripheral speed of the distributor roll (V2) The coating roll has a peripheral speed (V1) ratio (V2 / V1) of 0.4 to 0.6, and the metal sheet is coated between the coating roll and the backup roll that rotate in the same direction.

(Operation) As shown in FIG. 2, when the distributor roll 2 is in light contact with the distributor roll 2 through the coating film and the distributor roll 2 rotates forward with respect to the coating roll 1 having the relatively soft elastic sleeve 1a, the roll gap 9 The paint 5 of the paint films 5b and 5c 'flows in.

The paint 5 that has flowed in passes through a roll gap 9 between the coating roll 1 and the distributor roll 2.
Therefore, as shown by the curve 20 in FIG. 3, at the position p near the inlet side of the roll center line 16, the fluid pressure of the coating material 5 has a relatively high peak value P ₁ , and the center line 16
After leaving, the pressure tends to be relatively high.

As a result, for example, when the peripheral speed ratio (V ₂ / V ₁ ) is 1, a large number of bubbles 17 are generated at the exit side of the center line 16 and the paint film 5c transferred to the surface of the coating roll 1 is relatively large. Disturbance (thickness variation with time and location) occurs, which is considered to cause ribs (flow eyes).

As the peripheral speed ratio (V ₂ / V ₁ ) becomes lower, the shear generated in the paint 5 between the rolls becomes larger, so that the peak value P ₂ becomes lower as shown by the curve 21 in FIG. The negative pressure value after exiting is also reduced. And the peripheral speed ratio (V ₂
When / V ₁ ) is 0.6 or less, the pressure change between the rolls is small as described above, and the peripheral speed of the coating roll 1 is higher than that of the distributor roll 2. Since the paint film is stretched in the circumferential direction on the coating roll 1, the paint film
It is presumed that the ribs generated in 5c and the coating film 10 are extremely small. Further, since the coating film 10 is leveled before being heated and cured, the ribs are substantially eliminated.

On the other hand, when the peripheral speed ratio (V ₂ / V ₁ ) is lower than 0.4, the amount of the paint 5 flowing into the roll gap 9 from the paint film 5b of the distributor roll 2 is not sufficient, so that the paint film 5c has a paint breakage. As a result, a portion where the coating film 10 (FIG. 1) is not formed is formed on the sheet 6 and the coating cannot be performed. From this point, the peripheral speed ratio (V ₂ / V ₁ ) must be 0.4 or more.

The surfaces of the distributor roll 2 and the fountain roll 3 are both made of steel and rotate in the same direction at the same peripheral speed, and the distributor roll 2 has a small gap width w between the distributor roll 2 and the fountain roll. Therefore, the thickness of the paint film 5b transferred to the distributor roll 2 can be adjusted by adjusting the gap width w.

The distributor roll 2 further has a relatively soft elastic sleeve 1a, and is in light contact with the coating rolls 1 rotating in the forward direction through the coating film. Therefore, the roll gap 9 between the distributor roll 2 and the coating roll 1 is extremely narrow, and when the paint film 5b passes through the roll gap 9, the pressure (see FIG. 3) is generated as described above. However, since the relatively soft elastic sleeve 1a is easily dented by this pressure, the paint of the paint film 5b easily passes through the roll gap 9.

Therefore, the thickness of the paint film 5c transferred from the distributor roll 2 to the coating roll 1 depends on the peripheral speed ratio (V2 / V) of the distributor roll 2 and the coating roll 1.
When 1) is constant, it is proportional to the thickness of the paint film 5b transferred to the distributor roll 2. Therefore, the thickness of the coating film 10 applied to the metal sheet 6, and thus the thickness of the coating film after baking and drying is mainly determined by the gap width w.

Therefore, by keeping the peripheral speed ratio (V2 / V1) between the distributor roll 2 and the coating roll 1 within an appropriate range and adjusting the gap width w, the thickness of the coating film 10 applied to the metal sheet 6, that is, The film thickness after baking and drying can be determined.

As described above, since the paint of the paint film 5b easily passes through the roll gap 9, a drop of paint from the lower side of the roll gap 9 falls on the metal sheet 6 which normally moves horizontally below. Further, there is no possibility that a thick coating film portion in a drop shape is formed on the metal sheet 6 after baking and drying.

(Example) In FIG. 1, 1 is a coating roll, 2 is a distributor roll, 3 is a distributor roll 2
A fountain roll for forming a paint film 5b having a predetermined thickness on the peripheral surface of the coating roll 4, a backup roll for coating the sheet 6 in cooperation with the coating roll 1, and at the same time transferring in the direction of arrow A, and a moistening roll. Is. The surface of the coating roll 1 is made of a relatively soft elastic sleeve 1a such as rubber or elastic plastic (for example, the hardness is JIS A 35 degrees as described in page 13, line 2 to 3, but other The surfaces of the rolls are all rigid, eg steel.

Fountain roll 3 is distributor roll 2
Each of the rolls is driven by a drive mechanism (not shown) so that the rolls rotate in the normal direction and the distributor roll 2 also rotates in the forward direction with respect to the coating roll 1.

The peripheral speed of the full Aung Thein roll 3 is equal to the circumferential speed V ₂ of the distributor roll 2, the peripheral speed V ₁ of the circumferential speed V ₂ and the coating roll 1 of the distributor roll 2 ratio (V ₂ / V
₁ ) is specified to be 0.4 to 0.6. The peripheral speed of the backup roll 4 is equal to the peripheral speed V ₁ of the coating roll 1.

Distributor roll 2 and fountain roll 3
A wedge-shaped paint receiving plate 7 is provided in the vicinity of both ends of the upper nip portion between them, and the paint 5 flowing down in a curtain shape or a rod shape from a paint tank (not shown) is accumulated in the upper nip portion and a small amount of the paint. A pool 5a is formed. Reference numeral 8 is a tray for the paint 5 falling from the lower surfaces of the fountain roll 3 and the distributor roll 2.

The paint 5 in the paint reservoir 5a is rotated around the lower surface of the distributor roll 2 to form a paint film 5b, and then the roll gap 9
At, the coating film is transferred to the coating roll 1 to form a paint film 5c. The part 5b '(FIG. 3) of the paint film 5b is not transferred, and it goes around the distributor roll 2 as it is and returns to the paint reservoir 5a. Paint film 5c is coating roll 1
The coating film 10 is formed by applying the sheet 6 between the backup roll 4 and the backup roll 4. A part 5c '(FIG. 3) of the paint film 5c is not applied to the sheet 6 but reaches the roll gap 9 while being attached to the coating roll 1. The thickness (coating amount) of the coating film 10 is mainly determined by the gap width w between the distributor roll 2 and the fountain roll 3. It should be noted that the distributor roll 2 and the coating roll 1 are arranged in the roll gap 9 so as to be in light contact with each other via the paint film, that is, so-called kiss touch.

When the gap 12 between the sheets 6 passes between the coating roll 1 and the backup roll 4, or when the feeding of the sheet 6 is interrupted, the peripheral surface of the backup roll 4 is
A blade-shaped scraper 13 is provided to remove the transferred paint from the peripheral surface 4a in order to prevent the paint 5 from transferring to the peripheral surface 4a and soiling the peripheral surface 4a.

While the sheet 6 is passing, in order to prevent the peripheral surface 4a from becoming dry and having a large coefficient of friction and being scratched by the scraper 13, the peripheral surface 4a is constantly coated with the coating 15 by the moistening roll 14. Is lightly coated and lubricated.

The coating of the sheet 6 is carried out by the above apparatus as follows. Coating film to be formed on the sheet 6
After adjusting the gap width w between the fountain roll 3 and the distributor roll 2 according to the thickness of 10, the rolls are rotated in the rotation direction (arrow direction) shown in FIG. 1 to convey the sheet 6 (not shown). It is fed between the coating roll 1 and the backup roll 4 by the device.

The paint 5 flowing down from the paint tank forms a paint pool 5a and then moves to the peripheral surface of the distributor roll 2 to form a paint film 5b. The paint film 5b smoothly moves to the peripheral surface of the coating roll 1 in the roll gap 9 to form a fairly smooth paint film 5c. The paint film 5c is applied to the sheet 6 between the coating roll 1 and the backup roll 4 to form a fairly smooth coating film 10. This coating film
10 is dried by a drying device (not shown) to form a so-called rib smoothed coating film (not shown).

(Specific Example 1) Specific Example 1 Elastic sleeve 1a made of butyl rubber having a diameter of 339 mm and a hardness of JIS A (JIS K6301-1975) 35 degrees has a thickness of 17 mm and a length of 1190 mm.
Coating roll 1, 199 mm diameter steel distributor roll 2 (0.8S surface finish), 229 mm diameter steel fountain roll 3, and 339 mm diameter steel backup roll 4 (length of each roll 2, 3, 4) A coating apparatus of the type shown in FIG. 1 provided with a coating roll 1) is used to apply a vinyl organosol-based coating 5 to one side of an aluminum alloy sheet 6 having a thickness of 0.3 mm under the following conditions. Then, after forming the coating film 10, in a gas oven
A coating film was formed by baking and drying at 200 ° C. for 10 minutes. The results are shown in Table 1.

Coating conditions: coating roll 1 peripheral speed (V ₁ ): 105m /
Minutes.

Peripheral speed of distributor roll 2 (V ₂ ): As shown in Table 1, various peripheral speeds.

Peripheral speed of backup roll 4: 105m / min.

Paint 5: Viscosity 80 seconds / # 4 Ford cup, solid content 33% by weight.

The dry coating film has an average thickness of 9 μm except when the peripheral speed ratio (V ₂ / V ₁ ) of 0.3 is unpaintable and is yellowish overall, but the peripheral speed ratio V ₂ / V ₁ is 0.4 to 0.6. In the case of No. 3, the rib-like tatami mat pattern (so-called flow pattern) was visually smoothed and smooth.

Example 2 Elastic sleeve 1a made of butyl rubber with a diameter of 305 mm and hardness of JIS A (JIS K6301-1975) 35 degrees, thickness 17 mm, length 355 mm
Coating roll 1, a 123 mm diameter steel distributor roll 2 (0.8S surface finish), a 148 mm diameter steel fountain roll 3, and a 203 mm diameter steel backup roll 4 (each roll 2, 3, 4 long) (Equal to the length of the coating roll 1) is used to coat the epoxy ester amino-based paint 5 on one side of a tin-plated steel sheet having a thickness of 0.2 mm under the following conditions. After forming the coating film 10, 170 ° C × 1 in a gas oven
Baking and drying were performed for 0 minutes to form a coating film.

Coating conditions: coating roll 1 peripheral speed (V ₁ ): 90 m /
Minutes.

Distributor roll 2 peripheral speed (V ₂ ): peripheral speed ratio (V ₂
/ V ₁ ) was changed to 0.3, 0.4, 0.6, 0.8, 1.0, 1.2.

Peripheral speed of backup roll 4: 90m / min.

Gap width (w): 160 μm Paint 5: Viscosity 75 seconds / # 4 Ford cup, solid content 49% by weight.

The dry coating film is colorless and transparent as a whole with an average thickness of 6 μm except when the peripheral speed ratio (V ₂ / V ₁ ) of 0.3 is unpaintable, but in this case as well, the peripheral speed ratio V ₂ / V ₁ is At 0.4 to 0.6, a smooth and glossy coating film without macroscopic rib-shaped contiguous pattern (so-called flow pattern) was obtained.

(Effects of the Invention) The metal sheet coating apparatus of the present invention has a coating film portion that is thick like drops, ribs (flow eyes), and paint breakage even when the coating material has a relatively high viscosity and a relatively large coating amount. The effect that a uniformly smooth coating film without parts can be formed on a metal sheet is obtained.

From the viewpoint of corrosion resistance and the like, the coating film thickness usually has to be compensated for the minimum thickness. Therefore, the more the ribs are, the more paint is used. Therefore, according to the coating apparatus of the present invention, not only the appearance of the coated sheet is excellent, but also the amount of coating used can be smaller, which has the advantage of reducing the production cost.

A metal lid formed from a metal sheet having a smooth coating film, which is coated by the coating apparatus of the present invention, has an advantage that wrinkles are unlikely to occur on the seaming panel.

Further, in the coating apparatus of the present invention, the peripheral speed ratio (V2 / V1) between the distributor roll and the coating roll is kept constant within an appropriate range, and the gap width w is adjusted to adjust the thickness of the coating film applied to the metal sheet. That is, it has an advantage that the coating film thickness after baking and drying can be determined.

[Brief description of drawings]

FIG. 1 is a front view for explaining a coating apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged vertical sectional view of portion B in FIG. 1, and FIG. 3 is a coating fluid pressure distribution in a roll gap shown in FIG. It is a diagram showing an example of. 1 ... Coating roll, 1a ... Elastic sleeve, 2
...... Distributor roll, 3 …… Fountain roll, 4 …… Backup roll, 5 …… Paint, 6…
… Metal sheet.

Claims (1)

[Claims] 1. Fountain rolls: Distributor rolls that rotate in the same peripheral speed as the fountain rolls and have a slight gap between them and transfer the paint to the coating rolls: A coating roll that is in light contact with the distributor roll through the paint film and has a relatively soft elastic sleeve: and a backup roll that faces the coating roll. The surface of each roll other than the coating roll is a metal sheet made of steel. In the equipment, the distributor roll rotates forward with respect to the coating roll, and the ratio (V2 / V1) of the peripheral speed (V2) of the distributor roll to the peripheral speed (V1) of the coating roll is 0.4 to 0.6.
And a metal sheet coating apparatus that coats a metal sheet between a coating roll and a backup roll that rotate in a forward direction.