JPH0538861Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement of a double-sided coating device applied to a coating device for paper manufacturing machine products.

(Prior Art) Conventional coating devices for paper, etc. have mainly been those that coat both sides simultaneously using a roll coater, or coat one side using a blade coater or the like. However, in recent years, the need to increase production speed and save labor has increased, and double-sided simultaneous coating equipment with a single-sided blade and single-sided roll has gradually appeared.

FIG. 2 shows an example of the double-sided simultaneous coating apparatus.

Referring to the figure, the configuration of the double-sided simultaneous coating device will be described. On the roll coating side, the backing roll 1,
It is composed of a fountain roll 5 and a metering roll 6. One side of the blade is short-coated.
A coater head 4 called a dwell coater (product name) is provided, and a blade 3 is attached to the coater head 4.
is installed. This blade is equipped with a well-known mechanism 12 for constant pressure and constant angle.

To explain the method of coating paper or the like using such a coating device, first, when coating the material 2 to be coated such as paper that is guided by the guide roll 9 and runs, the coating on the roll side is carried out by the backing roll 1. The coating liquid 7 is supplied between the metering roll 6 and the fountain roll 5 provided on the circumference of the metering roll 6, and a constant linear pressure is applied between the fountain roll 5 and the metering roll 6, and the roll is moved as shown by the arrow in the figure. By rotating the metering roll 6, a coating liquid 7 having a constant thickness is deposited on the metering roll 6. Next, by applying a constant linear pressure between the backing roll 1 and the metering roll 6, a constant film thickness is obtained from the backing roll 6 to the backing roll 1.
Transfer to. The transferred coating liquid on the circumferential surface of the backing roll is applied to the upper surface of a coated material 2 such as paper guided by a guide roll 9.

On the other hand, regarding the coating on the blade side,
The coating liquid 7 is supplied from the lower part of the dwell coater head 4 and transferred onto the lower surface of the coated material 2 such as paper, and at the same time, a constant linear pressure is applied to the coated material 2 by the blade 3 to form a constant coating film. form a thickness.

In this way, both sides of the material 2 to be coated, such as paper, are coated simultaneously, and the product is then dried through a dryer (not shown) or the like. This kind of double-sided simultaneous coating equipment saves labor compared to single-sided coating, so
The need for installation as coating equipment is increasing.

(Problem to be solved by the invention) However, in the above-mentioned double-sided simultaneous coating device, the process from the metering roll 6 to the backing roll 1
When transferring the coating liquid to the metering roll 6, a part of the coating liquid remains on the surface of the metering roll 6. Due to this influence, the coating liquid film transferred to the backing roll 1 becomes a fine striped pattern in the circumferential direction of the roll, and if it is transferred as it is to paper or the like, a coating failure called a so-called ringing mark may occur.

The present invention has been devised to solve these problems, and is intended to provide a coating device that eliminates the coating hindrance caused by the ringing marks.

(Means for solving the problem) For this reason, the present invention is a method for coating a material to be coated, such as paper, which runs partially along a bucking roll, by coating one side with a roll coater and the other side with a blade coater. In a coating device that simultaneously applies a coating liquid to the backing roll and controls the coating film thickness, a cooling smoothing roll that reciprocates in the axial direction and is rotationally driven is provided with a predetermined nip pressure on the circumferential surface of the backing roll. This is a means for solving the above-mentioned problem.

In other words, in order to prevent ringing marks from occurring on the coated surface of the roll, the present invention (1) transfers the coating liquid from the metering roll to the bucking roll, and then attaches a smoothing roll so that it comes into contact with the bucking roll. thing.

(2) A mechanism is provided to give the smoothing roll reciprocating motion in the axial direction and to rotate it.

(3) The smoothing roll has a cooling structure.

It consists of each main part.

(Function) (1) By providing a smoothing roll, the coating film transferred to the backing roll is spread to a constant thickness by nip pressure.

(2) The coating fluid is a non-Newtonian fluid, and its viscosity changes depending on the shear rate. A typical coating liquid has a property that the viscosity decreases as the shear rate increases. Therefore, by applying shearing force to the coating film by reciprocating the smoothing roll, the dynamic viscosity of the coating film can be lowered, thereby increasing the flow of the coating liquid at the nip between the bucking roll and the smoothing roll. It becomes possible to easily make the thickness uniform. (→Kneading effect) (3) By cooling the smoothing roll, moisture in the atmosphere is condensed on the surface of the smoothing roll, and the coating film on the backing roll is prevented from being transferred to the smoothing roll.

(Example) The present invention will be described below with reference to illustrated embodiments.

FIG. 1 shows a typical embodiment of the present invention. The coating on the blade side is the same as the conventional one, so its explanation will be omitted here. Therefore, explaining the roll side coating, the coating liquid 7 supplied to the metering roll 6 and the fountain roll 5 applies a constant linear pressure between the metering roll 6 and the fountain roll 5, and simultaneously applies the coating liquid 7 as shown in the figure. By rotating the roll in the direction of the arrow, the coating liquid 7 of a constant thickness is deposited on the metering roll 6.

Next, bucking roll 1 and metaling roll 6
By similarly applying linear pressure in between, the coating liquid is transferred to the backing roll 1 and further transferred to a coated material 2 such as paper with a constant film thickness.

In the present invention, a smoothing roll 8 is provided on the circumference of the bucking roll 1 by applying a predetermined linear pressure, and the smoothing roll 8 is moved reciprocally in the axial direction of the bucking roll 1, and rotated by a rotational drive device (not shown). I try to do it. The direction of rotation is arbitrarily selected depending on the type of coating liquid and coating conditions, and is not limited to either forward or reverse here.

Further, the smoothing roll 8 has a cooling structure in which a cooling medium, such as cold water, enters from a line 10 and returns to the line 11 through the inside. Regarding the effect achieved by cooling the smoothing roll 8, as mentioned above, in order to make it difficult for the coating liquid film on the bucking roll 1 to be transferred to the smoothing roll 8, moisture in the atmosphere is condensed onto the smoothing roll surface. The aim is to

Therefore, the smoothing roll surface temperature needs to be below the dew condensation temperature. For example, in an atmosphere of 30°C and 50% humidity, the surface temperature should be kept below 18°C.

As a result of carrying out a coating test under the following conditions, it was found that the ringing marks on the backing roll surface could be eliminated to a level that did not cause any practical problems, and that the ringing marks could be prevented from causing problems in coating.

(1) Coating speed: 300m/min (2) Coating amount: 8 to 12g/m ² (3) Smoothing roll rotation speed: 20m/min (4) Smoothing roll nip: 3Kg/cm (Effect of the idea) As explained in detail above, according to the present invention, in a double-sided simultaneous coating device, a smoothing roll that performs rotational motion and reciprocating motion in the axial direction and has a cooling structure is installed on the circumference of the backing roll. (1) By kneading the coating film on the backing roll through reciprocating and rotating motion, the coating film thickness in the axial direction is made uniform and coating failures caused by ringing marks are eliminated.

(2) By cooling the smoothing roll, the coating film on the backing roll is prevented from being transferred onto the smoothing roll, thereby eliminating problems such as uneven coating caused by installing the smoothing roll.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a double-sided simultaneous coating apparatus showing a typical embodiment of the present invention, and FIG. 2 is a sectional view of a conventional double-sided simultaneous coating apparatus. Explanation of the main parts of the diagram, 1...Buckling roll, 3...Blade, 4...Shot dwell
Courtahed, 5... Juanten Roll, 6...
Metering roll, 8...Smoothing roll,
9...Guide roll.

Claims (1)

[Scope of utility model registration request] A roll coater is used to coat one side of a material to be coated, such as paper, which runs partially along a backing roll, and a blade coater is used to coat the other side, simultaneously applying coating liquid to both sides and controlling the coating film thickness. A double-sided simultaneous coating apparatus characterized in that a cooling smoothing roll that reciprocates in the axial direction and is rotationally driven is attached to the circumferential surface of the bucking roll so as to press it with a predetermined nip pressure. .