JP3477882B2 - Die coating method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die coating method, and more particularly to a method for controlling the position of a die so that a coating film formed by the die coating has a desired quality.

[0002]

2. Description of the Related Art Since die coating has many advantages over conventional roll coating, its range of application is being expanded. In die coating, there is a method (= opposite method) of coating a belt-like object (= object to be coated) that is partially wound around a backup roll while the belt-like object is on the backup roll, There is a method (= free span method) in which coating is performed while the belt-shaped material is located away from the backup roll. Japanese Unexamined Patent Publication No. 4-338262 describes a technique in which these two methods are carried out by a single die coating apparatus by moving the position of the roll.
That is, according to this Japanese Unexamined Patent Publication No. 4-338262, a support roll is installed downstream of the backup roll and above the backup roll, and a die is provided on a horizontal plane including the rotation axis of the backup roll or in the vicinity thereof. The support roll is moved forward and backward (on the same side as the die or on the opposite side of the die) so that the strip that has positioned the discharge end and has passed through the backup roll can travel while inclining to the same side as the die or the opposite side of the die. To be able to move to. In order to perform the opposite type coating with this apparatus, the support roll is moved to the side opposite to the die so that the strip immediately after coating is wrapped around the backup roll to run. Further, in the case of performing coating by the free span method, the support roll is moved to the same side as the die so that the strip is separated from the backup roll before coating. How far away from the die the coating is applied is determined by the diameter of the backup roll, the positional relationship between the horizontal plane including the rotation axis of the backup roll and the discharge end of the die, and the position of the support roll. Generally, the coating is performed while the strip does not run away from the die by more than 30 mm. Coating at such a position has a unique advantage over the ordinary free span method (see Japanese Patent Laid-Open No. 4-118076).

[0003]

In the ordinary opposite method and the above-mentioned opposite-free span switching method of Japanese Patent Laid-Open No. 4-338262, the ejection end of the die is installed close to the backup roll, and the ejection of the die is performed. The strip passes through the gap between the edge and the backup roll. The thickness of the coating film and the quality of the coating film are controlled by adjusting the gap between the discharge end of the die and the backup roll.
In the case of the opposite method, if the gap is wide, the coating film becomes thick, but if it is too wide, the coating film may have a rippled shape. In the case of the free span method disclosed in Japanese Patent Laid-Open No. 4-338262, if the gap is too wide, the coating film will have bald defects. This phenomenon tends to occur particularly when coating is performed at high speed.

When such a coating defect occurs, it is necessary to advance the die with respect to the backup roll to adjust the gap between the backup roll and the discharge end of the die to an appropriate value. However, the advance distance of the die is usually several μ to 10
It is only a few μ, and the gap between the discharge end of the die and the backup roll is extremely narrow, and the belt-like material is running through this gap, so when moving the die forward, the gap should not become too narrow. In addition, it must be done with great care and caution.

[0005]

According to the present invention, instead of advancing or retracting the die relative to the backup roll to adjust the spacing between the die and the backup roll, the die is moved upward or downward in place. The same effect as moving the die forward or backward can be obtained by simply moving the die by mm.

To explain the present invention in more detail, in the case of opposite coating, the coating material discharged from the die is
It is considered that the paint pool is formed between the lip of the die and the strip on the backup roll in the state as shown in FIG. In this state, if the width of the upper end portion (A portion in the figure) of the paint reservoir (= the gap between the downstream lip and the strip) becomes large, the paint in the paint reservoir runs short, and the ripple-shaped coating is applied as described above. It is considered that a film defect occurs. In this case, when the die is moved downward, the width of the upper end portion of the paint reservoir becomes narrow, which is as if the die were moved forward. Moreover, the moving distance of the die is several hundred to several thousand times larger than that in the case where the die is moved forward to make the width of the portion A the same, so that the moving distance can be easily adjusted.

In addition to this, when the die is moved downward, the width of the lower end portion (the portion B in the figure) of the paint reservoir becomes wider, and the paint deposit is larger than when the die is advanced. Since the amount of paint retained is large, it is easy to make the coating thickness uniform over the entire coating width. In addition, JP-A-4-338262
In the case of the No. Free span method, the coating is normally performed in the state shown in FIG. In this free span method, if the gap between the die and the backup roll is too wide, bald defects occur in the coating film because the paint pool formed between the discharge end of the die and the strip in FIG. It is considered that this is because the lower end portion is too large to be fully supported by the surface tension, the air entrained in the belt-like material partially enters there, and the paint in that portion runs short. In this case, when the die is moved upward, the size of the lower end of the paint pool becomes smaller, and the surface tension of the paint can maintain its shape constant, so that air enters and a bald defect occurs in the coating film. Can be prevented. Although the case of narrowing the gap has been described above, it is needless to say that the gap can be widened by moving up and down, and in this case as well, the moving distance can be made larger than that of the forward / backward movement, and thus the control is easy. The same benefits can be enjoyed. The vertical movement distance is usually 10 mm or less, especially 5 mm or less,
It can be said that the size is sufficiently larger than the moving distance of several μm to several tens of μm in the case of back and forth movement.

[0008]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. Example 1 An amylnium plate was coated by a free span method using the die coating apparatus as shown in FIG. The backup roll has a diameter of 350 mm, and the discharge port of the die is arranged slightly above the horizontal plane including the rotation axis thereof.
The die has a manifold diameter of 20 mm and a land length of 5
It is 0 mm, and the vertical interval between lands is 300 μm.

An aluminum plate (1100 material) having a thickness of 0.13 mm and a width of 910 mm was run at 50 m / min, and both ends were 5 m at a point 2 mm away from the backup roll.
Painting was performed leaving m units. When the gap between the aluminum plate and the die discharge end was set to 50 μm and coating was started aiming for a coating thickness of 5 μm, bald defects occurred in the coating. Then, the die was moved upward by 2 mm (there was about 25 mm between the discharge end of the die and the aluminum plate).
However, the bald defects disappeared and a good coating film was formed. The paint used was a polyester system and was supplied to the manifold of the die by a metering pump so that the coating film thickness was 5 μm.

Example 2 With the die coating apparatus used in Example 1, the support roll was moved to the opposite side of the die (right side in the figure), and the aluminum plate was coated by the opposite method. The aluminum plate was 1100 material having a thickness of 0.5 mm and a width of 1610 mm, which was run at 25 m / min and was coated with 5 mm left at each end. The coating was started aiming for a coating thickness of 50 μm, but since ripple-like defects occurred in the coating,
When the die was moved downward by 2 mm, the ripple-like defects were eliminated and a good coating film was formed. The paint used was polyester and the coating thickness was 50 with a metering pump.
It was supplied to the manifold of the die so as to have a thickness of μm.

[0011]

According to the present invention, in the die coating in which the discharge end of the die is installed close to the backup roll, the gap between the die and the backup roll can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a schematic view of an opposite-free span switching type die coating apparatus suitable for carrying out the present invention.

FIG. 2 is a schematic view of a discharge end portion of a die during coating by the opposite method.

FIG. 3 is a schematic diagram of a discharge end portion of a die during coating by a free span method in an opposite-free span switching type die coating apparatus.

[Explanation of symbols]

1 die 2 Downstream lip of the die discharge end 3 Upstream lip of the die discharge end Land of 4 dies 5 strips 6 backup roll 7 Support roll

Continuation of the front page (56) Reference JP-A-8-57389 (JP, A) JP-A-62-273080 (JP, A) JP-A-4-118076 (JP, A) JP-A-4-338262 (JP , A) JP 5-169000 (JP, A) JP 4-100570 (JP, A) JP 5-68927 (JP, A) JP 3-38272 (JP, A) 52-27964 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B01D 1/00-7/26 B05C 5/00-5/04

Claims (5)

(57) [Claims] 1. A die coating method in which paint is discharged from a die onto a strip that is partially wound around a backup roll that is supported substantially horizontally and the coating is performed. plane including the discharge end is in proximity to the backup roller so as to be substantially horizontally is moved established the die, and the die above or below the
Then, still 30m strip is separated from the backed Ppuroru
A method of controlling the quality of a coating film by performing coating while the vehicle is not running for more than m and running the belt-shaped material immediately after coating inclined to the same side as the die. 2. The strip is an aluminum plate.
The method according to claim 1, wherein 3. A backup station which is supported substantially horizontally.
In a die coating method in which paint is discharged from a die onto a strip that is partially wound around and running on a roll, the strip is an aluminum plate, and the rotation axis of the backup roll and the discharge end of the die are Place the die close to the backup roll so that the plane containing it is almost horizontal,
And controlling the quality of the coating film by moving the die up or down. 4. While the strip is on the backup roll
Performs coating, and a method according to claim 3, wherein the strip-like material immediately after coating, characterized in that the running inclined to the side opposite to the die. 5. The amount of movement of the die upward or downward is 10 mm.
The method according to any one of claims 1 to 4, wherein: