JPH11333351A - Coater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coater which is capable of stable coating in an always dispersed and stable state and does not require difficult control, such as feedback control. SOLUTION: This coater system of a circulation system forms a circulation system of a coating liquid to withdraw the greater part of the coating liquid 12 supplied from a coating liquid supply side flow passage on one end side of the liquid reservoir of the coating liquid 12 communicating with a slit 16 of a die head 15 for die coating having the slit 16 for coating from a coating liquid discharge side flow passage on the other end side and to return the same into a coating liquid tank 11. Precision transfer pumps of a plunger type are used for a supply pump P12 and return pump P13 before and behind the die head 15 in the system described above. The pressure fluctuation in the coating head 15 is eliminated and the coating application may be executed without using the difficult control, such as flow rate feedback. In addition, if the system is provided with a branch circulating flow passage 17 for circulating the coating liquid 12 to the coating liquid tank 11 at all times and a dispersing machine 13 dispersing the coating liquid 12 at all times is previously arranged, the highly dispersed coating liquid 12 is supplied to the die head 15 at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for applying a coating liquid such as a magnetic paint to a tape made of a plastic film.

[0002]

2. Description of the Related Art Conventionally, a method of applying a magnetic paint or the like using a die head has been widely used because a thin layer can be applied as compared with other methods. Conventional coating methods using the die head include, for example, those disclosed in JP-A-60-143866, JP-A-1-236968, and JP-A-5-293427. The purpose of these coating methods is to increase the fluidity of the coating liquid in the liquid reservoir of the die head and to make the discharge amount of the coating liquid uniform in the coating width direction in order to avoid the aggregation of the coating liquid. This is a method for stabilizing the surface smoothness and the coating thickness of the film uniformly.

[0003] In brief, the invention disclosed in each of the above-mentioned patent publications is described in the above-mentioned Japanese Patent Application Laid-Open No. Sho 60-143866. It is a method of applying the difference amount between the liquid supply amount and the withdrawal liquid amount while returning and appropriately circulating.

Further, in the inventions described in JP-A-1-236968 and JP-A-5-293427, a part of the coating liquid supplied from the coating liquid supply side of the die head is supplied to the other end of the coating liquid discharge side. From the coating solution supply side, and in the method described in JP-A-1-236968, a circulation pump is provided near the junction of the coating solution on the coating solution supply side and the coating solution on the coating solution discharge side. Yes, JP 5
In JP-A-293427, there is a circulation pump near the confluence of the coating liquid discharged from the coating liquid discharge side and the coating liquid on the coating liquid supply side.

[0005]

However, according to the coating method described in the above-mentioned patent publication, in which the coating liquid recirculates in the closed path, the coating liquid supplied into the closed path is supplied only for the amount of the coating liquid. At times, only a very small amount of coating liquid is supplied into the circulation channel, so that the coating liquid supplied a long time circulates in the circulation channel, and there is a disadvantage that a new coating liquid is not always applied. . Also, when feeding a new coating liquid into the annular flow path, only a small amount of replenishment is sent, so that the coating liquid does not smoothly enter the high-pressure annular flow path. It is necessary to have a configuration that controls the temperature of the vehicle very accurately.

In order to solve the above problem, Japanese Patent Laid-Open No. 1-23
Japanese Patent No. 6968 discloses a method in which a coating liquid is supplied from a coating liquid supply side of a die head and a difference between the coating liquid discharged from a coating liquid discharge side is extruded as a coating thickness.
In order to implement this method, it is necessary to accurately control the supply amount of the coating liquid from the coating liquid supply side and the discharge amount of the coating liquid from the coating liquid discharge side.

Further, according to the prior art, when a gear pump or a rotor pump is used as a circulating pump disposed near the junction of the coating liquid on the coating liquid discharge side and the coating liquid supply side, vibration of the gear pump and the like is reduced. It is transmitted to the piping that is the flow path for the coating liquid. Therefore, the pressure on the exit side of the die head may fluctuate during the circulation of the coating liquid. That is, when a coating film is applied with a coating thickness of 0.2 μm, about 60 cc / min is used. On the other hand, when a back pressure is applied, a leak is caused, a flow rate is reduced, and when a back pressure is 1 kg / cm ³ , a gear pump is used. About 80 cc / min with the rotor pump and about 90 cc / min with the rotor pump. As described above, the use of the circulation pump has a problem that the thickness of the coating film is greatly affected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a coating liquid coating apparatus which not only can stably apply a coating liquid in a constantly dispersed and stable state but does not require difficult control such as feedback control.

[0009]

An object of the present invention is to provide a coating liquid supply side flow at one end of a coating liquid reservoir communicating with a slit of a die coating coating head (die head) having a coating slit. In a circulation type coating method for forming a coating liquid circulation system in which most of the coating liquid supplied from the passage is pulled out from the coating liquid discharge side flow path at the other end and returned to the coating liquid tank, supply pumps before and after the die head are provided. A plunger-type precision transfer pump is used as the return pump, and there is no pressure fluctuation in the coating head, and the coating is performed without using difficult control such as flow rate feedback.

That is, the present invention provides a die head having a coating slit, a liquid reservoir communicating with the coating head,
A coating liquid supply-side flow path connected to one end of the liquid reservoir, a coating liquid discharge-side flow path connected to the other end of the liquid pool, the coating liquid supply-side flow path, and a coating liquid discharge-side flow path A supply pump and a return pump provided respectively in the coating liquid tank, and a coating liquid tank that supplies the coating liquid to the coating liquid supply-side flow path, where most of the coating liquid supplied to the die head is returned from the coating liquid discharge-side flow path In the coating device provided with, a coating device using a plunger type precision transfer pump for the supply pump and the return pump, there is no pressure fluctuation in the die head according to the present invention,
The coating liquid can be applied to the substrate without using difficult control such as flow rate feedback.

In addition, a branch circulation path is provided in the coating liquid supply side flow path for constantly circulating the coating liquid in the coating liquid tank without supplying the coating liquid to the die head. If a dispersing machine that constantly disperses the coating liquid is arranged in the liquid supply flow path, a highly dispersed coating liquid is always prepared by the dispersing machine, and the amount of the coating liquid is supplied by the supply pump after the dispersing machine. Only the coating liquid is supplied to the die head, and the rest is returned to the coating liquid tank via the branch circulation channel, whereby the coating liquid which is always highly dispersed can be supplied to the die head.

When supplying the coating liquid to the die head, a part of the highly dispersed coating liquid is returned to the branch circulation flow path after the disperser, and the supply of the coating liquid on the supply pump side comprising a plunger type precision transfer pump is performed. In the flow path, a valve for supplying another coating liquid is provided in the coating liquid supply side flow path on the downstream side of the branch portion of the branch circulation flow path, and a case where the coating liquid is actually supplied to the die head is branched. It is possible to prepare for the case where the coating liquid is circulated in a state of being highly dispersed only in the circulation channel.

Further, since the coating liquid in the branch circulation flow path branched from the coating liquid supply-side flow path only needs to be dispersed in a highly dispersed state, a type other than a plunger type precision transfer pump may be used. It is only necessary to provide an inexpensive pump.

Further, the present invention provides a coating head for die coating provided with a slit for coating, a liquid reservoir communicating with the coating head for a single coating head, and a liquid reservoir connected to one end of the liquid reservoir. Coating liquid supply-side flow path, a coating liquid discharge-side flow path connected to the other end of the liquid reservoir, and a plunger type provided in the coating liquid supply-side flow path and the coating liquid discharge-side flow path, respectively. A supply pump and a return pump composed of a precision transfer pump, and a coating liquid that supplies most of the coating liquid supplied to the coating head from the coating liquid discharge side flow path to the coating liquid supply side flow path again It also includes an applicator provided with two or more constituent units consisting of a tank.

The present invention can be preferably applied when a coating liquid in a thin film state such as a magnetic tape or a magnetic recording medium is applied to a substrate such as a film or a plate.

[0016]

FIG. 1 shows an embodiment of the present invention.
3 will be described together with FIG. In the example shown in FIG. 1, the coating liquid 2 in the tank 1 is constantly stirred by the stirrer 7 and waits for the application of the coating liquid. A line 6 for circulating the coating liquid is provided between the tank 1 and the die head 4. The coating liquid 2 in the tank 1 is supplied to the die head 4 via a valve 3 provided in the circulation line 6, a supply plunger type precision transfer pump P1, a filter F1, and a flow meter FM1. The coating liquid 2 is applied to the substrate (not shown) from the slit 5 of the die head 4, but most of the coating liquid 2 supplied to the die head 4 is returned to the tank 1 from the circulation line 6. At this time, a return plunger type precision transfer pump P2, a filter F2, and a flow meter F are also provided to the circulation line 6 on the return side of the coating liquid 2.
M2 is provided.

When the coating liquid 2 is applied to the substrate, the valve 3 is opened, and the pipe in the circulation line 6 is filled with the coating liquid 2 and circulated at a relatively high flow rate (eg, 5000 cc / min). 2 and the coating liquid 2 which is always highly dispersed is supplied to the die head 4.

The flow meters FM1 and FM2 are used as monitors only. At this time, the circulation amount of the coating liquid 2 by the plunger type precision transfer pumps P1 and P2 in the circulation line 6 is
Is the amount that fills the circulation line 6 with the coating liquid 2 in addition to the amount of the coating liquid applied from the slit 5 of the die head 4.

In this way, the coating liquid 2 always flows in the pipe of the coating liquid circulation line 6 and in the die head 4 at a relatively high flow rate with respect to the coating amount per unit time from the slit 5 of the die head 4. The internal pressure is stable, and aggregation of the coating liquid 2 can be prevented.

The coating thickness of the coating film is adjusted with respect to the set coating thickness.
The control is performed by increasing or decreasing the amount of the coating liquid 2 returned by the pump P2. Here, as the pumps P1 and P2, those of a plunger type precision transfer type which have little vibration and leak, do not decrease the flow rate even when a back pressure is applied, and have a small pulsating flow are used.

Next, another embodiment of the present invention will be described with reference to FIG. The coating liquid 12 in the tank 11 is constantly stirred by the stirrer 19 to be ready for coating. The coating liquid 12 is transferred by the circulation gear pump P11, and is passed through the filter F11, the flow meter FM11, and the disperser 13. At this time, the valve 14 is closed and the circulation line 1 is closed.
The application liquid 12 is returned to the tank 11 via. The circulation line 17 is filled with the coating liquid 12 and circulated at a relatively high flow rate (eg, 5000 cc / min).
When the coating liquid 12 that is always highly dispersed is applied to a substrate (not shown), the coating liquid 12 can be supplied to the die head 15.

When applying to the base material, the valve 14 is opened, the supply plunger type precision transfer pump P12 is passed through the filter F12 and the flow meter FM12, and the coating liquid 12 is sent to the die head 15. The supply plunger type precision transfer pump P12 is operated such that the supply amount of the coating liquid 12 becomes the set flow rate. At the same time, the application liquid 12 that has passed through the die head 15 is passed by the return plunger type precision transfer pump P13, passes through the filter F13 and the flow meter FM13, and returns to the tank 11 via the circulation line 18. At this time, the application liquid that has passed through the die head 15 is passed by the return plunger precision transfer pump P13 through the filter F13 and the flow meter FM13, and returns to the tank 11 via the circulation line 18.

A supply plunger type precision transfer pump P12 and a return plunger type precision transfer pump P12
13 is set to a flow rate smaller than that of the circulation gear pump P11 (example: 3000 cc / min). Further, the circulation amount of the coating liquid by the supply plunger type precision transfer pump P12 and the return plunger type precision transfer pump P13 is set such that the balance of the coating liquid 12 is slightly blurred from the slit 16 of the die head 15, Under this condition, the circulation line 18 is filled with the coating liquid, and the coating liquid is supplied into the die head 15.

The flow meters FM11, FM12, FM13 are only monitors. At this time, the coating liquid 12 is always supplied to the circulation line 18.
Flows through the pipe and the die head 15 at a relatively high flow rate with respect to the coating amount from the slit 16 of the die head 15, the pressure in the die head 15 is stabilized, and the aggregation of the coating liquid 12 can be prevented. .

When the coating liquid 12 is applied to the substrate, the return plunger-type precision transfer pump P13 is controlled to discharge the coating liquid 12 from the slit 16. At this time, the circulation gear pump P11 and the supply return plunger type precision transfer pump P12 flow the coating liquid 12 at the same flow rate as before,
The flow rate of the return plunger type precision transfer pump P13 is controlled to approach the set coating thickness. Here, the pump P1
2. For P13, use a plunger-type precision transfer system which has little vibration and leak, does not decrease its flow rate even when a back pressure is applied, and has little pulsation.

On the other hand, since the coating solution in the circulation line 17 branched from the circulation line 18 only needs to be dispersed in a highly dispersed state, an inexpensive type other than a plunger type precision transfer pump can be used. It is only necessary to provide the gear pump P11.

Next, an embodiment of the two-layer coating of the present invention shown in FIG. 3 will be described. The first coating liquid 22 in the tank 21 is stirred by the stirrer 29, and waits for coating on the base material. The first coating liquid 22 is transferred by the circulation gear pump P21, and passes through the filter F21, the flow meter FM21, and the disperser 23. At this time, the valve 24 is closed, and the first coating liquid 22 is returned to the tank 21 via the circulation line 27. The circulation line 27 is filled with the first coating liquid 22 and circulated at a relatively high flow rate (e.g., 5000 cc / min) to disperse the first coating liquid 22, and to constantly supply the highly dispersed first coating liquid 22 to the die head 25. Be ready to supply.

Further, the second coating liquid 32 in the tank 31 is stirred by the stirrer 37 and is kept on standby for coating on the base material. The second coating liquid 32 is transferred by the circulation gear pump P31, and passes through the filter F31, the flow meter FM31, and the disperser 33. At this time, the valve 34 is closed, and the second coating liquid 32 is returned to the tank 31 via the circulation line 35. The circulation line 35 is filled with the second coating liquid 32 and circulated at a relatively high flow rate (e.g., 5000 cc / min) to disperse the second coating liquid 32, and to constantly supply the highly dispersed second coating liquid 32 to the die head 25. Be ready to supply.

When applying the first coating liquid 22 to the substrate, the valve 24 is opened, and the plunger type precision transfer pump P22 is used to pass the filter F22 and the flow meter FM22 by the supply plunger type precision transfer pump P22. Send out. The application liquid supply of the supply plunger type precision transfer pump P22 is operated at a set flow rate. At the same time, the coating liquid 22 that has passed through the die head 25 is returned to the filter F23 and the flow meter FM2 by the return plunger type precision transfer pump P23.
3 and returns to the tank 21 via the circulation line 28.

A supply plunger type precision transfer pump P22 and a return plunger type precision transfer pump P22
23 sets the flow rate of the coating solution smaller than that of the circulation gear pump P21 (eg, 3000 cc / min). further,
The supply amount of the coating liquid by the supply plunger type precision transfer pump P22 and the return plunger type precision transfer pump P23 is set such that the coating liquid has a balance such that the coating liquid slightly bleeds from the slit 26 of the die head 25. Under these conditions, the inside of the return line 28 is filled with the coating liquid and circulated in the die head 25.

The flowmeters FM21, FM22, FM23 are only monitors. At this time, the coating liquid 22 is always in the pipe of the first coating liquid circulation line 28 and in the die head 25.
Flows at a relatively high flow rate with respect to the coating amount per unit time from the slit 26, so that the die head 2
The pressure inside 5 is stable, and the aggregation of the coating liquid 22 can be prevented.

When the first coating liquid 22 is applied, the return plunger-type precision transfer pump P23 is controlled to
The coating liquid 32 is discharged from 6. The coating thickness of the coating film is controlled by increasing or decreasing the amount of the first coating liquid 22 to be discharged by the return plunger-type precision transfer pump P23 with respect to the set coating thickness.

As described above, the pumps P22 and P23 are of a plunger type precision transfer type which has little vibration and leakage, does not decrease the flow rate even when a back pressure is applied, and has a small pulsating flow.

When the second coating liquid 32 is applied to the base material, the valve 34 is opened, and the filter F32 and the flow meter FM are supplied by the supply plunger type precision transfer pump P32.
The second coating liquid 32 is sent to the die head 25 through the second coating liquid 32. The application liquid supply of the supply plunger type precision transfer pump P32 is operated at a set flow rate. At the same time, the die head 2 is moved by the return plunger type precision transfer pump P33.
5 passes through the filter F33 and the flow meter FM33, and passes through the circulation line 36 to the tank 3
Return to 1. At this time, the second application liquid 32 supplied by the supply plunger precision transfer pump P32 and passed through the die head 25 passes through the filter F33 and the flow meter FM33, and returns to the tank 31 via the circulation line 36.

The supply plunger type precision transfer pump P32 and the return plunger type precision transfer pump P
33 sets a flow rate smaller than that of the circulation gear pump P31 (eg, 3000 cc / min). Further, the supply amounts of the coating liquid by the supply plunger type precision transfer pump P32 and the return plunger type precision transfer pump P33 are set such that the second coating liquid 32 is slightly balanced from the slit 26 of the die head 25. Then, the return line 36 is filled with the second coating liquid 32 under these conditions, and circulated through the die head 25.

The flow meters FM31, FM32, and FM33 are only monitors. At this time, the flow rate of the second coating liquid 32 in the pipe of the second coating liquid circulation line 36 and the flow rate of the coating liquid in the die head 25 is relatively high with respect to the coating amount from the slit 26, so that the die head 25 The internal pressure is stable, and the aggregation of the coating solution can be prevented.

When the second coating liquid 32 is applied, the return plunger type precision transfer pump P33 is controlled to
The coating liquid is discharged from 6. At this time, the circulation gear pump P31 and the supply return plunger type precision transfer pump P
Numeral 32 flows the coating liquid at the same flow rate as before, increases the flow rate of the return plunger type precision transfer pump P33, and approaches the set coating thickness of the coating liquid to the base material. The coating thickness of the coating film is controlled by increasing or decreasing the amount of the second coating liquid 32 discharged by the return plunger type precision transfer pump P33 with respect to the set coating thickness.

As described above, the coating system shown in FIG. 3 makes it possible to apply a thin coating of a coating liquid in two layers. For example, a magnetic layer can be applied very thinly and without unevenness. Further, by using the plunger type precision transfer pumps P32 and P33, difficult control such as flow rate feedback is not required.

In order to find specific set values of the above-described conditions, tests were performed using the processing timing of the disperser 33 and various types of pumps. The test results are shown in Tables 1, 2 and 4 and 5.

[0040]

[Table 1]

[0041]

[Table 2]

From the test results, by using the circulation system and the plunger-type precision transfer pump in combination, it became possible to apply the magnetic layer to a two-layer thin film having a uniform coating thickness of 0.2 μm level.

[0043]

According to the present invention, since a plunger-type precision transfer pump is arranged in a circulation line provided between a coating liquid tank and a die head, there is no leakage of the coating liquid, so that even if a back pressure is applied, discharge is performed. The pressure in the die head can be kept constant without reducing the amount and without requiring difficult control such as flow rate feedback, so that a very thin coating film can be applied evenly. In addition, by disposing a disperser in the circulation line, it is possible to always supply a highly dispersed coating liquid to the die head. Furthermore, it is possible to apply a two-layer thin film, for example, so that a magnetic layer can be applied very thinly without unevenness.

[Brief description of the drawings]

FIG. 1 is a diagram showing a coating liquid application system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a coating liquid application system according to an embodiment of the present invention.

FIG. 3 is a diagram showing a coating liquid application system according to an embodiment of the present invention.

FIG. 4 is a diagram showing transitions of a theoretical flow rate and an actual flow rate depending on the discharge pressure of a circulation pump used in a coating liquid application system according to an embodiment of the present invention.

FIG. 5 is a diagram showing transitions of a theoretical flow rate and an actual flow rate depending on a discharge pressure of a circulation pump used in a coating liquid application system according to an embodiment of the present invention.

[Explanation of symbols]

1, 11, 21, 31 Tank 2, 12, 22, 32 Coating liquid 3, 14, 24, 34 Valve 4, 15, 25 Die head 5, 16, 26 Slit 6, 17, 18, 27, 28, 35, 36 Line for coating liquid circulation 7, 19, 29, 37 Stirrer P1, P2, P12, P13, P22, P23, P3
2, P33 Plunger type precision transfer pump F1, F2, F11, F12, F13, F21, F2
2, F31, F32, F33 Filters FM1, FM2, FM12, FM13, FM21, FM
22, FM23, FM31, FM31, FM32, FM
33 Flow meter P11, P21, P31 Circulation gear pump

Claims (5)

[Claims] 1. A coating head for die coating having a slit for coating, a liquid reservoir communicating with the coating head, a coating liquid supply side flow path connected to one end of the liquid reservoir, A coating liquid discharge side flow path connected to the other end side,
The supply pump and the return pump provided in the coating liquid supply side flow path and the coating liquid discharge side flow path, respectively, most of the coating liquid supplied to the coating head is returned from the coating liquid discharge side flow path, and again. What is claimed is: 1. A coating apparatus comprising: a coating liquid tank for supplying a coating liquid to a coating liquid supply side flow path, wherein a plunger-type precision transfer pump is used as a supply pump and a return pump. 2. A branch circulation flow path for constantly circulating a coating liquid in a coating liquid tank without supplying the coating liquid to a coating head is provided in the coating liquid supply side flow path, and a branch flow path upstream of a branch portion of the branch circulation flow path. 2. The coating apparatus according to claim 1, wherein a disperser for constantly dispersing the coating liquid is disposed in the coating liquid supply flow path. 3. When supplying a coating liquid to a coating head,
A part of the highly dispersed coating liquid is returned to the branch circulation flow path after the disperser, and the other coating liquid is supplied to the coating liquid supply flow path on the supply pump side including a plunger type precision transfer pump. 3. The coating apparatus according to claim 2, wherein a valve is provided in the coating liquid supply side flow path on the downstream side of the branch portion of the branch circulation flow path. 4. The coating according to claim 2, wherein a pump other than a plunger-type precision transfer pump is provided in the branch circulation flow path branched from the coating liquid supply-side flow path. apparatus. 5. A coating head for die coating having a slit for coating, a liquid reservoir communicating with the coating head for a single coating head, and a coating connected to one end of the liquid reservoir. A liquid supply side flow path, a coating liquid discharge side flow path connected to the other end of the liquid reservoir, and a plunger type precision transfer pump provided in the coating liquid supply side flow path and the coating liquid discharge side flow path, respectively. From the supply pump and the return pump, and the coating liquid tank that supplies the coating liquid to the coating liquid supply-side flow path where most of the coating liquid supplied to the coating head is returned from the coating liquid discharge-side flow path. A coating apparatus comprising two or more configurations.