JP2013071044A - Coating apparatus and coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variation in film thickness of a coating film due to the pulsation of coating fluid.SOLUTION: There is provided a coating apparatus 100 which includes: a coating fluid supply pump 2 supplying coating fluid; a coating head 7 for coating a base material; main piping 3 for connecting from the coating fluid supply pump 2 to the coating head 7; and a coating fluid flow passage switching valve 4 which is provide in the main piping 3 and can be used for intermittent coating. The coating apparatus 100 further includes an accumulator 5 which can temporarily store the coating fluid and is provided between from the coating fluid supply pump 2 to the coating fluid flow passage switching valve 4. The accumulator 5 is arranged in such a manner that the position of the upper end of a gas space of the accumulator 5 is higher than the position of the ejection port of a coating head 7, and as a result, the coating apparatus 100 is durable against change in piping pressure with time and the variation in the film thickness due to the discharge pulsation generated from the coating fluid supply pump 2 is reduced.

Description

  The present invention relates to a coating apparatus and a coating method, and more particularly to a coating apparatus and a coating method that reduce film thickness variation of a coating film due to pulsation of a coating liquid.

In recent years, with the reduction in size and weight of mobile devices such as notebook personal computers and mobile phones, high energy density lithium ion secondary batteries are often used as power sources.
A lithium ion secondary battery is a metal foil generally called a current collector, and an electrode plate coated with a coating liquid containing an electrode active material, a conductive material, and a binder is interposed through an electrically insulating separator. It is manufactured by laminating, enclosing the laminated electrode plates in an exterior member, and injecting and sealing the electrolyte.

The electrode plate is formed by adjusting a coating liquid in which an electrode active material, a conductive material, and a binder are mixed, coating the substrate on a base material (metal foil) that is a current collector, and drying. Furthermore, the electrode plate is manufactured through a pressing step of pressing the current collector on which the electrode plate is formed as necessary, and then through a slitting / cutting step of cutting the pressed current collector into a predetermined size.
As a method for applying to the substrate, there is a method in which the coating liquid is continuously applied to the substrate and the electrodes themselves on the current collector plate are controlled by a slitting process and a cutting process. In recent years, an intermittent coating method has also been widely used in which a coating part coated with a coating liquid on a substrate and an uncoated part not coated with a coating liquid are sequentially formed.

In the process of applying to the current collector and drying, it is necessary to apply the coating liquid uniformly. As an industrial method for forming a coating film on a substrate, intermittent coating is generally performed by methods such as comma reverse, comma direct, die coating, and lip coating.
On the other hand, the battery capacity of a lithium ion secondary battery depends on the active material amount of the entire battery. Therefore, in order to increase the capacity, the electrode film thickness is generally set to 100 μm or more. In addition, the electrode surface shape and film thickness accuracy of the lithium ion secondary battery have a significant effect on the current collection performance, and it becomes an obstacle during winding and stacking of electrodes. Therefore, it is important to create an electrode with a uniform film thickness.

As a coating method for obtaining such a very thick coating film, among the coating methods described above, a coating liquid is discharged from a head having a slit having a certain width, and a coating having a desired thickness is applied to the surface of the object to be coated. A coating method using a slit die coater for forming a film has been widely adopted.
When forming a coating film on a substrate using a die coater, the slurry fed from the pump is usually temporarily stored in a manifold inside the head of the die coater, and the die coater head is brought close to the substrate to the head. The coating liquid is ejected from the slit-shaped nozzle provided, and a liquid pool called a bead is formed between the head and the base material that runs relatively at a constant interval, and the base material travels in this state. At the same time, the coating liquid is drawn out to form a coating film. This method is suitable for the operation of a highly viscous coating liquid, and is a method in which a very thick coating film can be obtained by combining with an appropriate pump. As an intermittent coating apparatus using such a die coater, for example, the one described in Patent Document 1 is known.

  In the conventional method, it is said that the uniformity of a certain film thickness can be ensured by strictly controlling the supply of the coating liquid. However, due to the influence of the pump that supplies the coating liquid and other vibrations of the drive unit, Pulsation occurs in the discharge of the coating liquid, and as a result, periodic unevenness and irregular variation may occur in the coating film. It is known that such irregularities and variations greatly affect the production of lithium ion secondary batteries. Patent Document 1 describes a method of driving the head to suck the coating liquid in the manifold and the nozzle to prevent thick coating of the coating film at the start of coating, but reduces variations in film thickness due to pulsation. There is no mention of the method of making it happen.

In order to obtain a more uniform coating film in the coating method using a die coater, minute discharge pulsation due to vibration of the pump that supplies the coating liquid, uneven movement of the rubbing part, vibration of the liquid supply piping, etc. It is necessary to completely eliminate vibration and vibration.
In general, as a means for removing the influence of discharge pulsation generated from a pump that supplies a coating liquid, it has been proposed to install a pressure accumulator such as an air chamber or an accumulator.

  Here, as a method of intermittently applying a coating film to a substrate using a die coater, a method of restricting the flow of coating liquid using a coating liquid flow path switching valve is widely known. In the method of performing intermittent coating using such a coating liquid flow path switching valve, since the pressure in the liquid feeding pipe may be negative, for example, in the liquid feeding pipe for the purpose of eliminating the influence of discharge pulsation, for example When the accumulator is installed, air leakage of the accumulator occurs, so that it is difficult to suppress the influence of the discharge pulsation generated from the pump for a long time.

In addition, as means for eliminating the influence of discharge pulsation generated from the pump that supplies the coating liquid, an accumulator for suppressing pulsation is provided between the pump and the head, and a flow path through which the coating liquid flows when coating is stopped There is also proposed a coating apparatus that suppresses film thickness variation by controlling the pressure of the pipe and keeping the pipe internal pressure constant (see, for example, Patent Document 2).
However, in this method of providing an accumulator and controlling the pressure of the flow path into which the coating liquid flows when the coating is stopped, the pressure is applied in real time to cope with the change in the flow characteristics of the coating liquid over time. Since it is necessary to adjust, it is indispensable to monitor the pressure in the flow path, and there is a problem that labor and cost increase.

JP-A-8-229481 JP 2006-107771 A

  The present invention has been made paying attention to the above-mentioned conventional unsolved problems, and connects at least a pump for supplying a coating liquid, a coating head for coating a substrate, and the pump to the coating head. In a coating apparatus having a main pipe and a coating liquid flow path switching valve that can be used for intermittent coating provided in the main pipe, it is possible to reduce variations in coating film thickness due to pulsation of the coating liquid. An object is to provide a coating apparatus and a coating method.

As a result of intensive studies, the inventor has provided a pressure accumulating portion between the pump for supplying the coating liquid and the coating head, and the height of the upper end of the gas space region in which the gas is filled is increased. The inventors have found that the above problem can be solved by making the height higher than the height of the discharge port of the coating head, and have completed the present invention.
A coating apparatus according to claim 1 of the present invention is a pump for supplying a coating liquid, a coating head for coating the coating liquid on a substrate, and for transferring the coating liquid from the pump to the coating head. A main pipe, a coating liquid supply valve that is provided in the main pipe and intermittently supplies the coating liquid to the coating head, and a pressure accumulating section that is provided in the main pipe. A pressure accumulating chamber for temporarily storing the coating liquid flowing in from the main pipe, and the pressure accumulating portion is located at the upper end position of the gas space region filled with the gas in the accumulating chamber, The coating head is disposed so as to be relatively higher than the position of the discharge port of the coating head.

The coating apparatus according to a second aspect is characterized in that a plurality of the pressure accumulating portions are arranged between the pump and the coating liquid supply valve of the main pipe.
The coating apparatus according to claim 3 is configured such that, of the plurality of pressure accumulating units, the volume of the gas space region of the pressure accumulating unit closer to the pump is the gas space of the pressure accumulating unit closer to the coating liquid supply valve. It is characterized by being equal to or larger than the volume of the region.

The coating apparatus according to claim 4 has a circulation channel connected to the coating liquid supply valve and circulates the coating liquid to the main pipe, and the coating liquid supply valve is connected to the coating head side and the circulation flow. The coating liquid is supplied by switching between the roadside and the roadside.
The coating apparatus according to claim 5 is characterized in that the pressure accumulating portion is arranged in a branch pipe branched from the main pipe.

The coating apparatus according to a sixth aspect is characterized in that the pressure accumulating portion is an accumulator.
Moreover, the coating method which concerns on Claim 7 of this invention is characterized by applying a coating liquid to a base material using the coating apparatus of any one of Claim 1-6. Yes.

  According to the present invention, a pump for supplying a coating liquid, a coating head for applying the coating liquid to a substrate, a main pipe for transferring the coating liquid from the pump to the coating head, and the main pipe A coating liquid supply valve that intermittently supplies the coating liquid to the coating head, and a pressure accumulating section provided in the main pipe, the pressure accumulating section being filled with an atmospheric pressure gas and the pressure accumulating section The pressure accumulating chamber temporarily stores the coating liquid flowing in from the main pipe, and the pressure accumulating portion has an upper end position of a gas space area filled with the gas in the pressure accumulating chamber at the outlet of the coating head. It arrange | positioned so that it might become relatively higher than a position. For this reason, it is possible to withstand changes in piping pressure over time, and to reduce film thickness variations due to discharge pulsation generated from the pump.

  In particular, a plurality of pressure accumulating sections are provided between the pump and the coating liquid supply valve, and the volume of the gas space area of the pressure accumulating section closer to the coating liquid supply valve is the volume of the gas space area of the pressure accumulating section closer to the pump. Equal to or better than Therefore, the pressure accumulator nearer to the coating liquid supply valve is affected by the pressure fluctuation of the main piping accompanying the operation of the coating liquid supply valve for intermittent coating, and as a result, the gas in the gas space region has escaped. In addition, the gas space region can be operated as a cushion for suppressing pressure fluctuation. Therefore, the film thickness variation can be reduced more reliably.

It is a schematic structure figure showing an example of a coating device concerning an embodiment of the present invention. It is a cross-sectional schematic diagram for demonstrating an example of the positional relationship of the coating apparatus which concerns on embodiment of this invention, and an accumulator. It is a cross-sectional schematic diagram for demonstrating an example of the positional relationship of the coating apparatus which concerns on embodiment of this invention, and several accumulators.

Below, the coating apparatus which concerns on embodiment of this invention is demonstrated. The embodiments of the present invention are not limited to the embodiments described below, and modifications such as design changes can be added based on the knowledge of those skilled in the art. Embodiments to which is added can also be included in the scope of the embodiments of the present invention.
FIG. 1 is a schematic configuration diagram showing an embodiment of a coating apparatus according to an embodiment of the present invention.

In the coating apparatus 100 according to the present embodiment, the coating liquid tank 1 is connected to the coating liquid supply pump 2 and is connected to the coating liquid channel switching valve 4 through the main pipe 3. Further, an accumulator 5 and a pressure gauge 6 are provided between the coating liquid supply pump 2 and the coating liquid flow path switching valve 4.
The coating liquid flow path switching valve 4 is provided with a coating liquid supply flow path 8 toward the coating head 7 and a coating liquid circulation path 9 toward the coating liquid tank 1.

In the coating apparatus 100 shown in FIG. 1, the coating liquid circulation channel 9 is connected to the coating liquid tank 1, but the coating liquid supply pipe 10 between the coating liquid supply pump 2 and the coating liquid tank 1 is used. The coating liquid may be circulated by connecting to
Although only one accumulator 5 is provided in FIG. 1, a plurality of accumulators 5 may be provided between the coating liquid supply pump 2 and the coating liquid flow path switching valve 4.

FIG. 2 is a schematic cross-sectional view for explaining the positional relationship between the coating apparatus 100 and the accumulator 5 shown in FIG.
As shown in FIG. 2, the accumulator 5 is provided in the main pipe 3, and the main pipe 3 is connected to the coating liquid channel switching valve 4, and one coating liquid supply provided in the coating liquid channel switching valve 4 is provided. A coating head 7 is connected to the flow path 8.

Then, the coating liquid supplied from the coating liquid supply flow path 8 via the main pipe 3 and the coating liquid flow path switching valve 4 is supplied to the manifold 7a of the coating head 7, and is not shown through the discharge port 11 from the slot 7b. It is discharged toward the substrate.
The accumulator 5 is a pressure accumulator that converts pressure energy of liquid, slurry, etc. into gas pressure energy and stores it. The accumulator 5 used in the present invention is not particularly limited as long as it is a general accumulator. The accumulator 5 includes a housing, a gas space region 14 filled with a gas having a predetermined pressure, which is defined by a piston, a bag, or the like in the housing, and a pressure accumulating chamber 13 into which the coating liquid flows from the main pipe 3. Composed.

The high-pressure coating liquid discharged from the coating liquid supply pump 2 is stored in the pressure accumulating chamber 13 of the accumulator 5 while compressing part of the gas sealed in the gas space region 14 of the accumulator 5 through the main pipe 3. As a result, the pulsation of the coating liquid supply pump 2 is such that the gas enclosed in the gas space region 14 acts as a cushion and is absorbed.
As shown in FIG. 2, the accumulator 5 is arranged such that the position of the upper end 12 of the gas space region 14 of the accumulator 5 is higher than the position of the discharge port 11 of the coating head 7. ing.

FIG. 3 is a schematic cross-sectional view showing an example when a plurality of accumulators are arranged in the coating apparatus 100.
In the main pipe 3, an accumulator 5 is connected to a position closer to the coating liquid flow path switching valve 4, and an accumulator 5 a is connected to a position closer to the coating liquid supply pump 2. This accumulator 5 a has a functional configuration equivalent to that of the accumulator 5.

As shown in FIG. 3, the coating liquid is supplied to the coating liquid supply flow path 8 through the main pipe 3 and the coating liquid flow path switching valve 4, and the coating liquid supplied from the coating liquid supply flow path 8. Is supplied to the manifold 7a of the coating head 7 and discharged from the slot 7b through the discharge port 11 toward a substrate (not shown).
The accumulators 5 and 5 a include gas space regions 14 and 14 a each filled with a gas (for example, nitrogen gas) having a predetermined pressure, and pressure accumulation chambers 13 and 13 a into which the coating liquid flows from the main pipe 3. At this time, the volume of the gas space region 14 is not less than the volume of the gas space region 14a. As shown in FIG. 3, the position of the upper end 12 of the gas space region 14 of the accumulator 5 and the position of the upper end 12a of the gas space region 14a of the accumulator 5a are both higher than the position of the discharge port 11 of the coating head 7. It is arranged to be.

  According to the present invention, at least the coating liquid supply pump 2 that supplies the coating liquid, the coating head 7 that coats the substrate, the main pipe 3 that connects the coating liquid supply pump 2 to the coating head 7, and the main pipe 3 is a coating apparatus having a coating liquid flow path switching valve 4 that can be used for intermittent coating, provided temporarily between the coating liquid supply pump 2 and the coating liquid flow path switching valve 4. Only the accumulator 5 that can store the coating liquid, or accumulators 5 and 5 a are provided, and the position of the upper end 12 of the gas space region 14 of these accumulators 5 and the position of the upper end 12 a of the gas space region 14 a of the accumulator 5 a are Only the accumulator 5 or the accumulators 5 and 5 a are arranged so as to be higher than the position of the discharge port 11. Therefore, the discharge pulsation generated from the coating liquid supply pump 2 is absorbed by the accumulator 5 or the accumulators 5 and 5a. Therefore, it is possible to provide a coating apparatus that can withstand changes in piping pressure over time and reduce variations in film thickness due to discharge pulsations generated from the coating liquid supply pump 2.

Here, the material of the accumulators 5 and 5a is not particularly limited, and there is no problem as long as it is a general material that is resistant to the solvent used and does not cause liquid leakage or gas leakage.
Moreover, the accumulators 5 and 5a should just be the structure provided with the gas space area | regions 14 and 14a in which a coating liquid is not stored, and the pressure accumulation chambers 13 and 13a in which a coating liquid flows in from the main piping 3 and a coating liquid is stored. . Therefore, for example, an L-shaped pipe connected to the main pipe 3, a straight pipe connected to the main pipe 3, and the tip sealed with a gasket may be used.

  The gas space regions 14 and 14a in which the coating liquid is not stored need only be filled with a substance that compresses and expands according to the inflow amount of the coating liquid, and is preferably a gas such as air or nitrogen gas. That is, the discharge pulsation generated from the coating liquid supply pump 2 is absorbed by the gas in the gas space regions 14 and 14a serving as a cushion. Therefore, the gas space regions 14 and 14a that do not store the coating liquid only need to be filled with a substance that compresses and expands according to the inflow amount of the coating liquid.

As described above, the coating apparatus 100 according to the embodiment of the present invention may include a plurality of accumulators. In this case, the upper ends 12 and 12a of the gas space regions 14 and 14a of the plurality of accumulators 5 and 5a, respectively. The position may be higher than the position of the discharge port 11 of the coating head 7.
Moreover, it is preferable that the difference between each accumulator upper end 12, 12a and the discharge port 11 of the coating head 7 is within 300 [mm]. If it is 300 [mm] or more, the constituent members of the accumulators 5 and 5a become large and the manufacturing cost increases, and the coating liquid stored in the accumulators 5 and 5a increases, which may increase the coating liquid loss. .

Further, when the position of the upper end of the accumulator is not defined as in the conventional coating apparatus, when the position of the upper end of the accumulator is lower than the position of the discharge port 11 of the coating head 7, the pipe internal pressure is high, and the accumulator Is completely filled with the coating liquid, there is a possibility that the discharge pulsation generated from the coating liquid supply pump 2 cannot be reduced.
Further, when the position of the upper end of the accumulator is lower than the position of the discharge port 11 of the coating head 7 as described above, it is possible to prevent the accumulator from being completely filled with the coating liquid by sending the compressed air to the accumulator. However, in order to send the compressed air, a compressor is required, which causes a problem that the coating apparatus becomes complicated and the cost increases.

The coating apparatus 100 of the present invention simply fills the gas space regions 14 and 14a with the coating liquid simply by making the upper end positions of the gas space regions 14 and 14a higher than the position of the discharge port 11 of the coating head 7. Can be avoided. Therefore, it can be realized with a simple configuration.
The plurality of accumulators 5, 5 a provided in the coating apparatus 100 according to the embodiment of the present invention shown in FIG. 3 is more than the accumulator 5 a on the side where the volume of the gas space regions 14, 14 a is closer to the coating liquid supply pump 2. The accumulator 5 on the side of the coating liquid flow path switching valve 4 may be larger or equal. The accumulator 5 on the side of the coating liquid flow switching valve 4 is more susceptible to fluctuations in the pressure of the main pipe 3 when switching the coating liquid flow path by intermittent coating than the accumulator 5a closer to the coating liquid supply pump 2. . Therefore, gas tends to flow out from the gas space region 14 serving as a cushion for suppressing discharge pulsation generated from the coating liquid supply pump 2. As a result, when gas flows out from the gas space region 14, the accumulator 5 may not function as a cushion.

However, the gas flows out of the gas space region 14 by setting the volume of the gas space region 14 in consideration of the flow of the gas space region 14 of the accumulator 5 closer to the coating liquid channel switching valve 4. Even in such a case, it can sufficiently fulfill the role of a cushion.
Moreover, in order to grasp | ascertain the state of the accumulators 5 and 5a, it is preferable to install the pressure gauge 6 in the main piping 3, and to measure the pressure of the accumulators 5 and 5a. The pressure gauge 6 may be installed at any position in the main pipe 3, but it is usually preferable to install it near the accumulator. For the plurality of accumulators 5 and 5a, a pressure gauge is installed near each of them. It is preferable to install.

As the coating liquid supply pump 2 in the coating apparatus 100 according to the embodiment of the present invention, a general pump corresponding to an organic solvent can be used, but a rotary volume type pump is preferable, and a Mono pump is particularly preferable.
Moreover, as main piping 3 in the coating apparatus 100 which concerns on embodiment of this invention, the general piping for pumps corresponding to an organic solvent can be used.

As the coating head 7 in the coating apparatus 100 which concerns on embodiment of this invention, the die head in which intermittent coating is possible is preferable. The die head is formed of a rectangular parallelepiped metal block having a predetermined width, and a generally wedge-shaped one whose tip is cut off obliquely can be used. The shape of the discharge port 11 is not particularly limited.
As the coating liquid flow path switching valve 4 in the coating apparatus 100 according to the embodiment of the present invention, the coating liquid circulation flow for circulating the coating liquid flow to the coating head 7 and the main pipe 3 as the coating liquid supply flow path 8 toward the coating head 7. For example, a general electromagnetic valve corresponding to an organic solvent, a valve having a mechanism for controlling a flow path by a piston, or a diaphragm can be used.

Further, in the coating apparatus 100 according to the embodiment of the present invention, the pressure of the coating liquid such as discharge pulsation generated from the coating liquid supply pump 2 between the coating liquid supply pump 2 and the coating liquid flow path switching valve 4. You may provide the buffer material which buffers a fluctuation | variation.
In the coating apparatus 100 according to the embodiment of the present invention, the accumulator 5 may be provided directly on the main pipe 3 or on a pipe branched from the main pipe 3. By providing the accumulator 5 in the pipe branched from the main pipe 3, the liquid feeding from the coating liquid supply pump 2 to the coating head 7 is not hindered at all, and the pressure fluctuation of the discharged liquid such as the discharge pulsation is prevented. Can be suppressed.

  Moreover, although the said embodiment demonstrated the case where intermittent coating was performed by switching a flow path with the coating liquid flow path switching valve 4, it is not restricted to this, and intermittent coating is performed by opening and closing a valve. Even if it is performed, it can be applied.

Hereinafter, the coating apparatus 100 according to the present invention will be described with specific examples and comparative examples. In addition, this invention is not restrict | limited by the following Example.
Example 1
<Coating device>
A MONO pump (manufactured by Hyojin Equipment Co., Ltd.) is connected to the coating liquid tank 1 as a coating liquid supply pump 2, and the MONO pump discharge port to the coating liquid channel switching valve 4 and from the coating liquid channel switching valve 4 to the coating head The die head as 7 was connected to the main pipe 3.

  An accumulator A serving as an accumulator 5a is provided in the main pipe 3 between the mono pump and the coating liquid flow switching valve 4 at a position close to the discharge port of the mono pump. The accumulator B as the accumulator 5 was installed at a position close to. Further, a coating liquid circulation channel 9 for returning the coating liquid from the coating liquid channel switching valve 4 to the coating liquid tank 1 is provided. A solenoid-controlled valve was used as the coating liquid flow path switching valve 4.

The position of the upper end of the gas space region of the accumulator A is 5 cm higher than the position of the discharge port 11 of the die head (coating head 7), and the position of the upper end of the gas space region of the accumulator B is the discharge port of the die head (coating head 7). The accumulators A and B are installed so as to be 7.5 [cm] higher than the position 11 and the volume of the gas space region 14 of the accumulator B is 1.5 times the volume of the gas space region 14a of the accumulator A. It adjusted so that it might become.
<Coating liquid>
Lithium manganate, polyvinylidene fluoride, a conductive additive, and N-methylpyrrolidone were mixed to prepare a coating solution having a viscosity of 5000 [mPa.s].
<Base material>
As a coating substrate, a PET film having a width of 300 [mm] and a thickness of 75 [μm] was used.
<Coating conditions>
The coating liquid supply pump 2 was rotated at 30 [rpm], and intermittent coating was performed for 60 minutes to prepare a coating film.

(Example 2)
The accumulator C is connected to the main pipe 3 between the MONO pump as the coating liquid supply pump 2 and the coating liquid flow switching valve 4 at a position near the discharge port of the MONO pump, and the coating liquid supply outlet of the coating liquid flow switching valve 4 is discharged. The accumulators D are respectively installed at positions close to the outlets, and the positions of the upper ends of the gas space regions of the accumulators C and D are both 5 cm higher than the position of the discharge port 11 of the die head (coating head 7). The volume of the gas space regions 14 and 14a was adjusted to be equal. A coating film was prepared under the same conditions as in Example 1 except for this.
(Comparative Example 1)
An accumulator E is connected to the main pipe 3 between the MONO pump (coating liquid supply pump 2) and the coating liquid flow switching valve 4 at a position near the discharge port of the MONO pump, and the coating liquid supply outlet of the coating liquid flow switching valve 4 is discharged. The accumulators F were respectively installed at positions close to the outlets, and the upper ends of the gas space regions of the accumulators E and F were both lowered by 5 [cm] from the discharge port 11 of the die head (coating head 7). A coating film was prepared under the same conditions as in Example 1 except for this.
(Comparative Example 2)
An accumulator G is placed in the main pipe 3 between the mono pump (coating liquid supply pump 2) and the coating liquid channel switching valve 4 at a position close to the outlet of the mono pump, and the coating liquid supply port outlet of the coating liquid channel switching valve. The accumulator H is installed at a position close to each other, and the position of the upper end of the gas space area of the accumulator G is 8 cm higher than the position of the discharge port of the die head (coating head 7). Each accumulator is installed so that the position is 4 [cm] higher than the position of the discharge port of the die head so that the volume of the gas space area of the accumulator H is 0.5 times the volume of the gas space area of the accumulator F. It was adjusted. A coating film was prepared under the same conditions as in Example 1 except for this.

(Evaluation)
Of the coating films prepared in Examples 1 and 2 and Comparative Examples 1 and 2, a piece of 20 [mm] × 100 [mm] from the center of the coating film immediately after the start of coating and after coating for 60 minutes. Cut out each, measure the film thickness using a contact-type continuous film thickness meter (manufactured by Anritsu Co., Ltd.), and calculate the increase rate Hi (%) of the maximum value Hmax with respect to the minimum value Hmin of the film thickness from the following equation (1). Asked.

Hi = (Hmax−Hmin) / Hmin × 100 (1)
The results are shown in Table 1.
In Table 1, “○” indicates that the increase rate Hi does not exceed 2%, “△” indicates that the increase rate Hi is 2% to 6%, and “×” indicates that the increase rate Hi exceeds 6%. .

In the coating apparatus 100 of (Example 1) and (Example 2), a coating film having a uniform film thickness could be stably applied from immediately after the start of coating to after 60 minutes.
On the other hand, in the coating apparatus of (Comparative Example 1), variation in the film thickness of the coating film was observed immediately after the start of coating. This is because the position of the upper end of the gas space region of the accumulator is lower than the discharge port 11 of the coating head, so that the coating liquid pressure applied to the accumulator is high, the accumulator is filled with the coating liquid, and the accumulator is effective. I guessed it was weakened.

Moreover, in the coating apparatus of (Comparative Example 2), the coating film thickness was uniform immediately after the start of coating, but after 60 minutes, the coating film thickness was uneven. This is presumed that the pressure in the main pipe 3 fluctuated over time, and the accumulator near the coating liquid flow path switching valve 4 was filled with the coating liquid, and the effect of the accumulator was weakened.
From the above, the effect of the present invention was confirmed.

  According to the coating apparatus of the present invention, in a coating film that is intermittently coated, the coating apparatus can withstand a change in piping pressure over time as compared with a conventional coating apparatus, and reduce variations in film thickness due to discharge pulsation generated from a pump. As a result, the industrial utility value is high. Therefore, the present invention can be suitably used for electrode coating of a lithium ion secondary battery that requires strict control of the electrode film thickness.

DESCRIPTION OF SYMBOLS 1 Coating liquid tank 2 Coating liquid supply pump 3 Main piping 4 Coating liquid flow path switching valve 5, 5a Accumulator 6 Pressure gauge 7 Coating head 8 Coating liquid supply flow path 9 Coating liquid circulation flow path 10 Coating liquid supply piping 11 Discharge port 12 , 12a Accumulator gas space region upper end 13, 13a Pressure accumulating chamber 14, 14a Gas space region 100 Coating device

Claims (7)

A pump for supplying the coating liquid;
A coating head for applying the coating liquid to a substrate;
A main pipe for transferring the coating liquid from the pump to the coating head;
A coating liquid supply valve that is provided in the main pipe and intermittently supplies the coating liquid to the coating head;
A pressure accumulating portion provided in the main pipe,
The pressure accumulating section has a pressure accumulating chamber that is filled with gas at atmospheric pressure and temporarily stores the coating liquid flowing in from the main pipe,
The pressure accumulating section is arranged so that the position of the upper end of the gas space region filled with the gas in the pressure accumulating chamber is relatively higher than the position of the discharge port of the coating head. Engineering equipment.   2. The coating apparatus according to claim 1, wherein a plurality of the pressure accumulating units are arranged between the pump and the coating liquid supply valve in the main pipe.   The volume of the gas space region of the pressure accumulating portion closer to the pump among the plurality of pressure accumulating portions is equal to or larger than the volume of the gas space region of the pressure accumulating portion closer to the coating liquid supply valve. The coating apparatus according to claim 2. A circulation passage connected to the coating liquid supply valve and circulating the coating liquid to the main pipe;
4. The coating liquid supply valve according to claim 1, wherein the coating liquid supply valve is configured to switch between the coating head side and the circulation flow path side to supply the coating liquid. Coating equipment.   The coating apparatus according to claim 1, wherein the pressure accumulating unit is arranged in a branch pipe branched from the main pipe.   The coating apparatus according to claim 1, wherein the pressure accumulating unit is an accumulator.   A coating method, wherein a coating liquid is applied to a substrate using the coating apparatus according to any one of claims 1 to 6.

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