JP3300801B2 - Reverse roll coater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-roll reverse roll coater having an applicator roll and a backup roll which rotate in opposite directions.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional three-reverse roll coater, in which an applicator roll 1 having a smooth surface and a metering roll 10 having a smooth surface reversely rotated with respect thereto. And a backup roll 2 made of rubber. The amount of the coating liquid 7 applied to the applicator roll 1 is adjusted by a metalling roll 10, and then the coating liquid 7 is transferred from the applicator roll 1 to the web 4. ing. In this case, the rotational speeds of the three rolls 1, 2, and 10 are independently controlled independently of each other, and the relative surface speed between the applicator roll 1 and the metering roll 10, and the applicator roll 1 and the backup roll The relative surface velocities with respect to No. 2 are different.

On the other hand, a two-roll type gravure coater is also known, in which a gravure roll in which countless cells are densely provided on the entire outer peripheral surface and a backup roll in contact with the gravure roll via a web are provided. Both rolls in the case are rotating in the same direction.

[0004]

In the conventional reverse roll coater, one of the main factors for determining the coating thickness on the web 4, that is, the thickness of the coating film 7a, is the applicator roll 1
There is a nip interval between the nip and the metering roll 10. The problem is that the nip interval between the rolls 1 and 10 cannot be set small when the main purpose is to make the coating film 7a uniform and thin. That is, the roundness of the two rolls 1 and 10 is not perfect, and the deflection of the bearings of the two rolls 1 and 10 is added synergistically. Therefore, there is a limit in dimensioning the nip interval as small as possible. For this reason, the conventional reverse roll coater has not been able to satisfy both the demands for uniformity and thinning, even though the surface smoothness of the coating film 7a is excellent.

Further, the pressing force of the backup roll 2 in the reverse roll coater needs to be transferred so that the measured coating liquid 7 is completely peeled off the smooth surface of the applicator roll 1 by the web 4. Therefore, it is ideal that the pressing force of the backup roll 2 is originally set as small as possible. However, there were limitations here. That is, the total pressure acting on the web in the nip between the two rolls 1 and 2 tends to be too high. Further, the smooth surface of the applicator roll 1 is in full contact with the rubber backup roll 2 via the web 4 in the roll axis direction, and the contact area is large. In addition, since both rolls 1.2 are reversed, both rolls 1.2
The frictional resistance to the web 4 in the nip is large. These act synergistically so that the web 4 is fed, that is, the rotation of the backup roll 2 intermittently collides with the gun gun, and a horizontal stripe parallel to the roll axis is formed in the coating film 7a on the web 4. In addition, the web 4 is likely to be wrinkled or fluctuated in tension.

In addition, when the coating liquid 7 is handled in a wide range, the ideal viscosity of the three rolls 1, 2, and 10 is considered in consideration of the viscosity, density, web feed speed, nip pressure, and the like. There is also a problem where the speed ratio needs to be adjusted, and this setting work becomes very difficult. Even with the best adjustment, the coating 7a
It was difficult to make the film uniform and thin. On the other hand, in the gravure coater, the coating amount is mainly determined by the shape and size of the cell and the angle of the doctor blade, so that the coating film 7a can be made uniform. Therefore, it is possible to cope with thinning to some extent. However, in this case, since the gravure pattern appears on the coating film on the web, the biggest problem is that the leveling step needs to be subsequently performed.

Accordingly, an object of the present invention is to provide a reverse roll coater in which the coating film on the web does not have streaks, and the coating film on the web can be effectively made uniform and thin.
Another object of the present invention is to provide an easy-to-use reverse roll coater which does not require strict control of the rotation speed ratio between rolls.

[0008]

According to the present invention, as shown in FIG. 1, an applicator roll 1 and a backup roll 2 which is in contact with the applicator roll 1 via a web 4 are provided. the backup roll 2 is inversely rotated, it is provided densely over the whole surface of the recess 5 of the innumerable the outer peripheral surface of the applicator roll 1, Apu
Surface speed of locator roll 1 and backup roll 2
That the ratio is set to 1.0-1.5: 1.0,
Nip pressure between cater roll 1 and backup roll 2
Contact but it is set to 0.2~0.5kg / cm, the applicator roll 1, in the direction of rotation on the hand side from the contact point between the backup roll 2, the outer peripheral surface of the applicator roll 1 It is necessary to have a doctor blade 6 that acts.

[0009]

The coating liquid 7 is filled in the depression 5 on the applicator roll 1, and the excess coating liquid 7 is scraped off from the roll surface by the doctor blade 6. Next, the coating liquid 7 in the dent 5
Transfer to the surface of the web 4 guided by the backup roll 2. However, since the two rolls 1 and 2 are rotating in the opposite directions, the coating 7a on the web 4 is in a state where the pattern of the dents 5 is erased and the coating is smooth and solid. At this time, in the nip between the two rolls 1 and 2, the web 4 comes into line contact with the surface of the applicator roll 1, but the contact area between the web 4 and the applicator roll 1 is reduced by the presence of the recess 5. As a result, the frictional resistance to the web 4 decreases. If the frictional resistance to the web 4 is reduced, the tension of the web 4 becomes uniform without fluctuation, and the coating film 7a on the web can be made uniform. At the same time, the pressing force of the backup roll 2 can be dramatically reduced.

[0010]

According to the present invention, therefore, it is possible to reduce the thickness of the coating film 7a without limit by simply selecting the size and shape of the recess 5 while ensuring the smoothness of the coating film 7a possessed by the reverse roll coater itself. Uniformization can be achieved at the same time. Specifically, in the case of the water-based coating liquid 7, the coating film 7a on the web 4 has conventionally been wet at a lower limit of 10 g / m ² , but in the present invention, it has been applied to a very thin coating of ² g / m ^{2 in a} wet state. It can be formed. There is no vertical or horizontal streak in the coating film 7a.

The metering of the coating liquid 7 on the applicator roll 1 can be achieved by scraping off with the doctor blade 6, so that the reverse roll coater of the present invention suffices with a two-roll system in which the conventional metering roll 10 is omitted. As a result, it is possible to eliminate the streaking phenomenon of the coating film 7a on the web 4 due to the deviation of the roundness of the conventional metering roll 10 and the runout of the bearing portion.

The surface speed ratio between the applicator roll 1 and the backup roll 2 is set to 1.0 to 1.5: 1.0.
And the nip pressure of both rolls 1.2 is 0.2 to 0.5 kg / cm
By this, the coating film 7a can be thinly and uniformly applied and formed.
You .

[0013]

FIG. 1 shows a two-roll reverse roll coater according to the present invention.
Denotes a backup roll made of rubber having elasticity, 3 denotes a coating liquid tank, and 4 denotes a web. The backup roll 2 elastically contacts the applicator roll 1 via the web 4.

The rotation speed of the applicator roll 1 and the backup roll 2 is controlled independently, and the backup roll 2 rotates in reverse with respect to the applicator roll 1. The relative surface speed ratio (linear speed ratio) of the two rolls 1 and 2 may be 1: 1 but is preferably 1.0 to 1.
5: Set within the range of 1.0 . On the outer peripheral surface of the applicator roll 1, countless dents 5 are densely provided in a grid pattern over the entire surface. The total opening area of the recess 5 is 70 to 8
It is about 0%.

If the opening area of each dent 5 is reduced, the surface speed ratio between the two rolls 1 and 2 can be increased. However, the processing accuracy of the dent 5 is limited. When the linear velocity of the web 4 exceeds 1.5 times the linear velocity of the backup roll 2, it becomes difficult to apply the coating liquid 7 to the web 4 thinly. In this sense, the surface speed ratio of the two rolls 1 and 2 is
1.0-1.5: 1.0 is preferred. It should be noted that the depth of each of the recesses 5 is not a critical factor for uniform coating, and about 30 μm is sufficient. The applicator roll 1, and a doctor blade 6 which Setto acting on the outer circumferential surface of the applicator roll 1 in the direction of rotation on <br/> hand side from the contact point between the backup roll 2.

The coating liquid 7 in the coating liquid tank 3 is directly picked up on the outer surface of the applicator roll 1. Each recess 5 on the roll 1 is filled with the coating liquid 7, and the excess coating liquid 7 is scraped off from the roll surface by the doctor blade 6. Next, the applicator roll 1 is applied to the web 4 pressed against the applicator roll 1 by the backup roll 2.
The upper coating liquid 7, that is, the coating liquid 7 in the dent 5 is transferred. Since the two rolls 1 and 2 are rotating in opposite directions during this transition, the coating liquid 7 is applied to the web 4 in a smooth solid state instead of the pattern of the recess 5.

The applicator roll 1 has a large number of dents 5 formed densely. The contact area of the web 4 with the roll 1 is reduced by the presence of the dents 5.
The frictional resistance applied to the surface is low. Therefore, the coating liquid 7 could be transferred and applied to the web 4 thinly and uniformly by making the shape and size of the recess 5 precise without causing any fluctuation in the tension of the web 4. At that time, the nip pressure between the applicator roll 1 and the backup roll 2 is usually 2.0 to 5.0 kg.
/ Has been set in cm, but 1/10 0.2 of the present invention
0.5kg / cm, you can configure up to a further 1/100 of 0.02~0.05Kg / cm.

Specifically, while feeding the web 4 at a line speed of 200 m / min using the coating liquid 7, the linear velocity ratio between the backup roll 2 and the applicator roll 1 is set to 1:
Set to 1.3 and set the nip pressure between both rolls 1 and 2 to 0.03 kg
/ Cm, the coating film 7a of the coating liquid 7 transferred to the web 4 could be formed as a wet and smooth 6 g / m ² . Similar good results were obtained even when the linear velocity ratio between the two rolls 1 and 2 was 1: 1.

[Brief description of the drawings]

FIG. 1 is a side view of a reverse roll coater according to the present invention.

FIG. 2 is a side view of a conventional reverse roll coater.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 applicator roll 2 backup roll 3 coating liquid tank 4 web 5 dent 6 doctor blade 7 coating liquid

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-231350 (JP, A) JP-A-3-38182 (JP, U) JP-A-63-35826 (JP, Y1) Yuji Harasaki, 3. 3 Reverse Roll Coater, 3.4 Gravure Coater, Introduction to Coating Equipment and Operating Technology, Japan, General Technology Center Co., Ltd., April 2, 1991, p. 75-96 (58) Field surveyed (Int. Cl. ⁷ , DB name) B05C 1/08 B05D 1/28

Claims (1)

(57) [Claims] 1. An applicator roll 1 and a backup roll 2 which is in contact with the applicator roll 1 via a web 4. The backup roll 2 rotates in reverse with respect to the applicator roll 1. the outer peripheral surface is provided with densely over the entire surface countless depressions 5, the surface velocity ratio between the applicator roll 1 and the backup roll 2 is 1.0 to 1.5: is set to 1.0, the applicator Roll 1 and backup roll 2
Flop pressure, is set to 0.2~0.5kg / cm, the applicator roll 1, in the direction of rotation on the hand side from the contact point between the backup roll 2, the outer peripheral surface of the applicator roll 1 A reverse roll coater provided with a doctor blade 6 acting in contact.