JP3569720B2 - Lip coater type coating equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lip coater type coating apparatus in which a nozzle head having a doctor edge is arranged below a backing roll, and a coating liquid is sprayed from the nozzle head by applying pressure to coat the web.
[0002]
[Prior art]
As described above, the following is known as a lip coater type coating apparatus for coating a web such as a film or paper with a coating liquid (Japanese Patent Publication No. 6-223).
[0003]
That is, a comma-type doctor edge is provided on the upper surface of the nozzle head, a first liquid reservoir is provided in the width direction of the inside of the nozzle head, and a front surface of the nozzle head faces the lower peripheral surface of the backing roll. A liquid reservoir wall is provided upright to leave a gap for web running, and a second liquid reservoir chamber is formed by the lower peripheral surface of the backing roll, the liquid reservoir wall, the doctor edge, and the upper surface of the nozzle head.
[0004]
With this lip coater type coating apparatus, the web travels to the doctor edge through the second reservoir chamber filled with the coating liquid, and the coating liquid is coated by the linear pressure of the blade edge of the doctor edge. Things.
[0005]
[Problems to be solved by the invention]
In the above-described coating apparatus, when the transport speed of the web is low, air is hardly mixed into the second liquid storage chamber, and air bubbles and the like are formed in the coated portion applied to the web. Does not occur.
[0006]
However, recently, in order to improve production efficiency, the number of cases where a coating liquid is applied while the web is being conveyed at a high speed is increasing. However, when the web is conveyed at such a high speed to apply the coating liquid, when the web is carried into the second liquid storage chamber, a portion of the gap between the liquid storage wall and the lower peripheral surface of the backing roll is required. However, there has been a problem that air bubbles are mixed in the above.
[0007]
In view of the above problems, the present invention provides a lip coater type coating apparatus in which air bubbles are not mixed into the coating surface even when the web is transported at a high speed.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is provided with a nozzle head having a doctor edge below a backing roll, sprays a coating liquid from the nozzle head by applying pressure, and lowers the lower peripheral surface of the backing roll of the nozzle head. A lip coater-type coating device for coating a web traveling from front to back, wherein a doctor edge is provided on an upper surface of the nozzle head, and a first liquid reservoir is provided in a width direction inside the nozzle head. An outlet for the coating liquid from the first reservoir is provided on the upper surface of the nozzle head located in front of the doctor edge, and a front portion of the nozzle head is provided below the backing roll. A liquid storage wall is erected to leave a gap for web running toward the peripheral surface, and a pair of side walls are arranged on both sides between the nozzle head and the backing roll, and the pair of side walls is disposed. In a lip coater type coating apparatus in which a wall, a lower peripheral surface of the backing roll, a liquid reservoir wall, a doctor blade and a second liquid reservoir chamber closed by an upper surface of the nozzle head are formed, The upper surface is an inclined surface facing the lower peripheral surface of the backing roll, and an inclined surface inclined so that a distance between the lower peripheral surface of the backing roll and the lower peripheral surface of the backing roll decreases from the rear surface of the liquid storage wall toward the clearance surface. The second reservoir is formed so as to expand forward from the outlet of the outflow channel to be larger than the volume of the outflow channel, and the volume gradually decreases as approaching the blade edge of the doctor edge. It becomes, and the pressure of the air balance to be entering the pressure of the coating liquid to be ejected in the gap between the lower peripheral surface and said reservoir wall of said backing roll The second liquid reservoir chamber wherein is closed as a lip coater type coating apparatus, characterized in that the higher than atmospheric pressure.
[0009]
The invention according to claim 2 is provided with a pressure gauge for measuring the internal pressure of the second liquid reservoir, and the pressure of the coating liquid supplied to the second liquid reservoir so that the pressure measured by the pressure gauge becomes a constant pressure. 2. The lip coater type coating apparatus according to claim 1, further comprising control means for controlling the amount.
[0010]
A third aspect of the present invention is the lip coater type coating apparatus according to the first aspect, wherein the doctor edge is a comma type which bulges in an arc shape in a vertical cross section and becomes a wedge shape.
[0011]
The invention according to claim 4, wherein the doctor edge is formed by connecting two surfaces extending in the width direction of the web linearly in the width direction at an obtuse angle. It is.
[0012]
The invention according to claim 5 is the lip coater type coating apparatus according to claim 1, wherein the inclined surface forming the upper surface of the reservoir wall is arc-shaped.
[0013]
According to a sixth aspect of the present invention, the inclined surface forming the upper surface of the reservoir wall is formed by connecting two surfaces extending in the width direction of the web linearly in the width direction at an obtuse angle. It is a lip coater type coating device of the description.
[0014]
[Operation]
In the lip coater type coating apparatus of the present invention, since the upper surface of the liquid reservoir wall is constituted by the gap surface and the inclined surface, even when the web is transported at a high speed, the liquid is transferred from the gap between the backing roll and the liquid reservoir wall. There is no air mixing.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
<First embodiment>
Hereinafter, a lip coater type coating apparatus 10 according to a first embodiment of the present invention will be described with reference to FIGS.
[0016]
FIG. 1 is a side view of the coating apparatus 10, and FIG. 3 is a cross-sectional view taken along line II in FIG.
[0017]
The backing roll 12 runs the web W from the right side to the left side of the coating apparatus 10 in FIG.
[0018]
Below the backing roll 12, a nozzle head 14 for applying a coating liquid to the web W is disposed. The head body 16 of the nozzle head 14 has substantially the same width as the backing roll 12, and is provided with a doctor edge 18 at the top.
[0019]
The doctor edge 18 is a comma-shaped doctor edge 18 formed in a circular arc shape in vertical section. The web W runs in the gap between the backing roll 12 and the doctor edge 18. The front surface 16a of the head body 16 is formed as a flat surface. A jet port 20 of the coating liquid is opened in the front surface 16a.
[0020]
The lid 22 of the head main body 16 is detachably attached to the front surface 16a of the head main body 16 by bolts 23. On the rear surface of the lid 22, a recess 24 is provided in the width direction. By combining the head main body 16 and the lid 22 with bolts, the first liquid storage chamber 26 is formed in the width direction inside the nozzle head 14 by the front surface 16 a of the head main body 16 and the concave portion 24 of the lid 22. An outflow passage 28 is formed in the upper part of the first liquid storage chamber 26 so as to be continuous with the first liquid storage chamber 26 in the width direction. The outflow passage 28 extends vertically upward, and an outlet 28 a is provided between a front part of the doctor edge 18 and a front end of the nozzle head 14. The coating width of the web W is determined by the length of the outlet 28a in the width direction. Therefore, when the length in the width direction of the lid 22 is changed, the coating width L of the web W changes.
[0021]
The liquid reservoir wall 30 has substantially the same width as the lid 22, and is detachably attached to an upper portion of the front surface of the lid 22 by bolts (not shown). A gap for running the web W is left between the upper end of the liquid reservoir wall 30 and the lower peripheral surface of the backing roll 12.
[0022]
The liquid reservoir wall 30 will be described in more detail with reference to FIG.
[0023]
As shown in FIG. 2, the upper surface of the liquid reservoir wall 30 includes a gap surface 52 facing the lower peripheral surface of the backing roll 12 and an inclined surface 54 formed continuously from the rear end of the gap surface 52. It is configured.
[0024]
The gap surface 52 is formed in an arc shape along the lower peripheral surface of the backing roll 12.
[0025]
The inclined surface 54 is formed of a surface formed in an arc shape from the rear surface 56 of the liquid reservoir wall 30 and then inclined so that the distance from the lower peripheral surface of the backing roll 12 gradually decreases. Therefore, the space in this portion is formed so as to gradually decrease as it approaches the gap surface 52 of the liquid storage wall 30. Then, as shown in the enlarged view of FIG. 2, the angle θ between the line extending backward of the gap surface 52 and the inclined surface 54 is formed to be an acute angle.
[0026]
The second reservoir chamber 32 is formed by a space formed by the front surface of the doctor edge 18, the upper surface of the lid 22, and the rear surface of the liquid reservoir wall 30, and both sides of this space are formed below the upper surface of the nozzle head 14 and the backing roll 12. It is formed by closing with a pair of side walls 34, 34 arranged between the peripheral surface. The inner volume of the second reservoir chamber 32 is larger than the volume of the outflow channel 28 because it is in a state of expanding forward from the outlet 28 a of the outflow channel 28.
[0027]
The side walls 34, 34 are slidably provided between the upper surface of the nozzle head 14 and the lower peripheral surface of the backing roll 12, and the bottom surface of the side wall 34 is provided with an outlet 28 a of the outflow passage 28 opened in the width direction. It is formed so that it can be closed.
[0028]
A slit 36 is provided in the head main body 16 below the doctor edge 18. One end of the slit 36 is opened in the width direction on the rear upper surface of the head main body 16, and the slit 36 is provided to be inclined downward along the width direction and forward. A plurality of adjustment bolts 38 penetrate the slit 36 at regular intervals in the width direction so as to be orthogonal to the slit 36. The end of the adjustment bolt 38 faces the rear surface 16b of the nozzle head 14, and the width of the slit 36 can be adjusted by adjusting the degree of screwing of the adjustment bolt 38 from the rear surface 16b. If the width of the slit 36 changes, the blade edge of the doctor edge 18 moves up and down, and can be adjusted up and down with a width of 2 μm to 3 μm. Since a plurality of adjustment bolts 38 are provided in the width direction, the adjustment bolt 38 closest to the cutting edge to be moved up and down is adjusted.
[0029]
The holding member 40 is provided below the center of the nozzle head 14. A double rod type air cylinder 42 is vertically arranged on the holding member 40. The air cylinder 42 is screwed to the lower surface of the head body 16 of the nozzle head 14 at the upper end of the cylinder tube.
[0030]
Below the inside of the holding member 40, a scale holding member 44 is arranged. Inside the scale holding member 44, a magnescale 45 (trade name) which is a magnetic displacement measuring scale is arranged. The top of the magnescale 45 is in contact with the lower end of the piston rod of the air cylinder 42, so that the vertical displacement of the piston rod can be detected. When the air cylinder 42 of the holding member 40 moves up and down, the deflection of the nozzle head 14 can be adjusted up and down with a width of 20 μm to 30 μm.
[0031]
The pump 46 is for pumping the coating liquid, and is connected to the ejection port 20 of the head body 16. The pressure at which the pump 46 feeds the coating liquid is controlled by an operation signal DS from a microcomputer 48 described later.
[0032]
A pressure gauge 50 made of a piezoelectric element such as a ceramic sensor is provided inside the second liquid storage chamber 32 and measures the internal pressure of the second liquid storage chamber 32. The pressure gauge 50 outputs the measured pressure to the microcomputer 48 by a pressure signal AS which is an electric signal.
[0033]
The microcomputer 48 is connected to the pressure gauge 50 and the pump 46. The pressure signal AS output from the pressure gauge 50 is input, and an operation signal DS is output to the pump 46.
[0034]
(Operating state)
An operation state of the coating apparatus 10 having the above configuration will be described with reference to FIG.
[0035]
The thickness of the coating liquid on the web W is determined by the gap between the backing roll 12 and the doctor edge 18 and the internal pressure of the second liquid storage chamber 32.
[0036]
The web W is caused to run in the gap between the backing roll 12 and the doctor edge 18. The coating liquid is diffused from the pump 46 in the width direction of the nozzle head 14 in the first liquid storage chamber 26 and is uniformly jetted from the outlet 28 a of the outflow passage 28 into the second liquid storage chamber 32. Control is performed such that the inside of the nozzle 32 is maintained at a constant pressure (hereinafter, referred to as reference pressure). In this control, the microcomputer 48 performs feedback control on the amount discharged by the pump 46 so that the pressure inside the second liquid reservoir 32 measured by the pressure gauge 50 becomes the reference pressure. Details will be described later. The reference pressure is set so that the coating liquid fills the second liquid storage chamber 32 and does not overflow from the gap between the liquid storage wall 30 and the backing roll 12.
[0037]
The web W travels to the doctor edge 18 after passing through the second liquid storage chamber 32 filled with the coating liquid, and the coating liquid is applied by the linear pressure of the blade edge of the doctor edge 18. In this case, the pressure of the coating liquid is made uniform by passing the coating liquid through the narrow outflow passage 28, and the second liquid reservoir 32 expands forward from the outlet 28 a of the outflow passage 28, and the outflow passage 28. , It is easy to maintain the inside of the second liquid storage chamber 32 at a reference pressure higher than the atmospheric pressure.
[0038]
First, the operation when the web W is carried into the second reservoir chamber 30 through the gap between the reservoir wall 30 and the backing roll 12 will be described with reference to FIG.
[0039]
The web W is carried into the second liquid storage chamber 32 through a gap between the lower peripheral surface of the backing roll 12 and the liquid storage wall 30 and the gap surface 52.
[0040]
On the other hand, the coating liquid is jetted from the outlet 28 a of the outflow passage 28, and flows as the jet flow D shown in FIG. The coating liquid having reached the position of the inclined surface 54 flows through the space gradually narrowing along the inclined surface 54 as a jet flow E toward the gap portion, and flows along the inclined surface 54 with the inclined surface 54 and the gap surface 52. It flows to the border. However, in this portion, since the air is going to enter the inside of the second liquid storage chamber 32 due to the carry-in of the web W, the coating to be ejected at the boundary between the gap surface 52 and the inclined surface 54 is performed. The pressure of the liquid balances with the pressure of the air to enter, so that no air bubbles are mixed. Then, the coating liquid that is about to be ejected to the outside is pushed back by the pressure of the air that is about to enter, and becomes a return flow F. The coating liquid of the return flow F flows together with the web W in the direction of the doctor edge 18 to form an entrainment flow A.
[0041]
As described above, when the inside of the second liquid reservoir chamber 32 is maintained at a constant reference pressure, the pressure of the coating liquid to be ejected and the pressure of the air to be penetrated in the gap between the liquid reservoir walls 30. Is balanced, so that air does not mix into the second liquid storage chamber 32. For this reason, even when the transport speed of the web W is increased, no bubbles are generated on the coated surface as in the related art. For example, the conventional transport speed is limited to 200 m / min or less, but in the case of the coating apparatus 10, air bubbles are not mixed even at 300 m / min or more.
[0042]
Conventionally, air was mixed in unless the gap between the upper end of the reservoir wall and the backing roll was reduced as much as possible. However, in the case of the coating device 10, the gap surface 54 of the reservoir wall 30 and the backing roll 12 As long as the pressure of the coating liquid to be ejected and the pressure of the air to be infiltrated are balanced, air is not mixed even if it is wider than the conventional gap.
[0043]
Next, the operation of applying the coating liquid to the web W will be described with reference to FIG.
[0044]
Since the doctor edge 18 is of a comma type, the volume of the second reservoir chamber 32 gradually decreases as the blade edge of the doctor edge 18 approaches, and accordingly the pressure applied to the web W gradually increases. By the adjustment described above, the coating liquid does not overflow outside the second liquid storage chamber 32. Therefore, the entrainment flow A of the coating liquid and the jet flow B of the coating liquid from the outlet 28a of the outflow passage 28 due to the movement of the web W do not become the swirling flow C in the same direction and become an unstable flow. . Therefore, the amount of the coating liquid on the surface of the web W before reaching the doctor edge 18 does not change in the width direction, and the coating amount on the web W does not become uneven in the width direction.
[0045]
A state where the internal pressure of the second liquid storage chamber 32 is maintained at the reference pressure will be described based on the block diagram of FIG.
[0046]
When the internal pressure of the second liquid storage chamber 32 rises above the reference pressure due to external factors such as uneven rotation of the pump, a change in the viscosity of the coating liquid, and a change in the liquid temperature, the internal pressure is increased by the pressure signal AS from the pressure gauge 50. The rise is transmitted to the microcomputer 48. The microcomputer 48 lowers the pressure of the pump 46 for feeding the coating liquid by the operation signal DS. When the pressure of the coating liquid decreases, the internal pressure of the second liquid storage chamber 32 decreases and returns to the original pressure. Conversely, when the internal pressure of the second reservoir chamber 32 becomes lower than the reference pressure, the microcomputer 48 increases the pressure of the pump 46 for feeding the coating liquid to increase the internal pressure of the second reservoir chamber 32.
[0047]
When the nozzle head 14 is bent in the width direction, the center of the nozzle head 14 is vertically displaced by the air cylinder 42 of the holding member 40 to correct the deflection. In the present embodiment, one holding member 40 is provided at the center of the nozzle head 14, but the number is not limited to this, and a plurality of holding members may be provided.
[0048]
The cutting edge of the doctor edge 18 is finished only by machining. However, perfect linearity cannot be obtained with the current processing method, and small undulations occur in the width direction. Therefore, the blade edge of the doctor edge 18 is vertically changed by 2 μm to 3 μm by the adjustment bolt 38 to finely adjust the undulation of the blade edge to approximate a straight line.
[0049]
<Second embodiment>
Next, a second embodiment will be described with reference to FIG.
[0050]
The difference between the first embodiment and the present embodiment lies in the shape of the upper surface of the doctor edge 18.
[0051]
That is, in the first embodiment, the upper surface is formed in an arc shape, but in the present embodiment, as shown in FIG. 5, the two surfaces extending in the width direction of the web W are linearly formed obtusely in the width direction. Thus, the rate at which the volume of the second liquid storage chamber 32 decreases at the linear portion connected linearly is suddenly changed.
Also in the present embodiment, when the web W is carried into the second reservoir chamber 32, air does not enter from the gap of the portion of the reservoir wall 30, so that no bubbles are generated on the coating surface. .
[0052]
<Third embodiment>
Next, a coating apparatus 10 according to a third embodiment of the present invention will be described with reference to FIG.
[0053]
The difference between the first embodiment and the present embodiment lies in the structure of the liquid reservoir wall 30.
[0054]
That is, as shown in FIG. 6, the liquid reservoir wall 30 is composed of a liquid reservoir wall main body 58 and an auxiliary member 62 attached to a rear upper portion of the liquid reservoir wall main body 58 by a bolt 60.
[0055]
The upper surface of the liquid reservoir wall main body 58 forms a gap surface 52, and the upper surface of the auxiliary member 62 forms an inclined surface 54.
[0056]
Thus, even in the coating apparatus 10 having only the conventional liquid reservoir wall main body 58, the inclined surface 54 can be formed by attaching the auxiliary member 62 with the bolt 60, and the first embodiment As in the example, no air bubbles enter the second liquid storage chamber 32.
[0057]
<Fourth embodiment>
Next, a fourth embodiment will be described with reference to FIG.
[0058]
The difference between the first embodiment and the present embodiment lies in the shape of the inclined surface 54.
[0059]
In the inclined surface 54 of the first embodiment, the linear inclined surface 54 is formed after being formed in an arc shape from the rear surface 56. However, in the present embodiment, a linear surface composed of two surfaces is combined. The shape was changed.
[0060]
Also in this case, since the second liquid storage chamber 32 is formed so as to gradually become smaller toward the gap surface 52, bubbles are mixed even when the carrying-in speed of the web W increases as in the first embodiment. Nothing.
[0061]
【The invention's effect】
In the lip coater type coating apparatus of the present invention, since the upper surface of the liquid reservoir wall is constituted by the gap surface and the inclined surface, even if the web is transported at a high speed, the gap between the backing roll and the liquid reservoir wall can be obtained. No air is mixed from the air.
[Brief description of the drawings]
FIG. 1 is a side view of a coating apparatus according to a first embodiment of the present invention.
FIG. 2 is an enlarged vertical sectional view of the coating apparatus.
FIG. 3 is a sectional view taken along line II in FIG. 1;
FIG. 4 is a block diagram of a coating device, a microcomputer, and a pump.
FIG. 5 is an enlarged vertical sectional view of a coating apparatus according to a second embodiment.
FIG. 6 is an enlarged longitudinal sectional view of a coating apparatus according to a third embodiment.
FIG. 7 is an enlarged vertical sectional view of a coating apparatus according to a fourth embodiment.
[Explanation of symbols]
10 lip coater type coating device 12 backing roll 14 nozzle head 16 head body 16a front surface 18 of head body doctor edge 22 lid 24 concave portion 26 first liquid reservoir Chamber 28 Outflow passage 28a Outflow passage outlet 30 Liquid reservoir wall 32 Second reservoir chamber 34 Side wall

Claims (6)

A nozzle head having a doctor edge disposed below the backing roll, and a coating liquid sprayed from the nozzle head under pressure to travel from the front to the back of the nozzle head on the lower peripheral surface of the backing roll. A lip coater type coating device for coating
A doctor edge protrudes from the upper surface of the nozzle head,
A first liquid storage chamber is provided in a width direction inside the nozzle head,
On the upper surface of the nozzle head located in front of the doctor edge, an outlet of the coating liquid from the first reservoir is provided,
At the front of the nozzle head, a liquid storage wall is erected, leaving a gap for web running toward the lower peripheral surface of the backing roll,
A pair of side walls are arranged on both sides between the nozzle head and the backing roll,
In the lip coater type coating apparatus in which a pair of side walls, a lower peripheral surface of the backing roll, a liquid reservoir wall, a second reservoir chamber which is more closed with an upper surface of the doctor edge and the nozzle head,
The upper surface of the reservoir wall is
A gap surface facing the lower peripheral surface of the backing roll,
An inclined surface inclined from the rear surface of the liquid reservoir wall toward the gap surface so as to decrease a distance from a lower peripheral surface of the backing roll,
The second liquid reservoir chamber, together are formed the greater than the volume of脹let alone the outlet channel in front of the outlet of the outlet channel, the volume enough to approach the edge of the doctor edge, gradually decreases, and the Atmospheric pressure is applied to the closed second reservoir so that the pressure of the coating liquid to be ejected and the pressure of the air to be penetrated in the gap between the lower peripheral surface of the backing roll and the reservoir wall are balanced. A lip coater type coating device characterized by being higher. A pressure gauge for measuring the internal pressure of the second reservoir is provided,
2. A lip coater type coating according to claim 1, further comprising control means for controlling an amount of the coating liquid supplied to said second reservoir so that the pressure measured by said pressure gauge becomes a constant pressure. apparatus. The doctor edge,
2. A lip coater type coating apparatus according to claim 1, wherein said lip coater type coating apparatus is a wedge-shaped comma type bulging into a vertical cross section arc. The doctor edge,
2. A lip coater type coating apparatus according to claim 1, wherein two surfaces extending in the width direction of the web are linearly connected in the width direction at an obtuse angle. The inclined surface forming the upper surface of the reservoir wall,
2. The lip coater type coating apparatus according to claim 1, wherein the coating apparatus has an arc shape. The inclined surface forming the upper surface of the reservoir wall,
2. A lip coater type coating apparatus according to claim 1, wherein two surfaces extending in the width direction of the web are linearly connected in the width direction at an obtuse angle.

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