JPH11223594A - In-line viscosimeter, die coater and viscosity control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-line viscosimeter which has a function to compute the uniformity in the width direction of a coating operation and by which a power row index to compute the uniformity can be found with sufficient accuracy, to provide a die coater and to provide a viscosity control method. SOLUTION: An in-line viscosimeter 30 is featured so as to be provided with at least two installed continuity parts 33, 36 which comprise spaces of respectively different sizes, pressure measuring means 34, 37 which are arranged before and after the continuity parts 33, 36 and which measure the pressure of liquids introduced into the continuity parts 33, 36 and flow-rate measuring means 35, 38 which measure the flow rate of the liquids introduced into the continuity parts 33, 36. A die coater 20 is provided with the in-line viscosimeter 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line viscometer for applying an active material using a die coater, applying a resist to a glass substrate, and other uniform coatings, a die coater using the in-line viscometer, and a viscosity management method.

[0002]

2. Description of the Related Art As a conventional apparatus for monitoring the flow characteristics of an in-line coating solution of a die coater, there is a falling ball type in-line viscometer. This falling ball type in-line viscometer drops a spherical or piston-shaped weight into a tube filled with liquid and calculates the viscosity from the falling speed of the weight.
Here, FIG. 4 shows a structure of an in-line viscometer 1 of a type in which a piston-shaped weight is dropped.

In the in-line viscometer 1, a piston-shaped weight 3 having a diameter smaller than the inner diameter of the pipe 2 by a predetermined amount is provided inside the pipe 2. A hole-shaped introduction portion 4 for flowing a liquid from inside to the inside of the tube 2 is formed. When the piston-shaped weight 3 moves up and down, the liquid flows in and out of the gap between the pipe 2 and the weight 3, and the viscosity of the liquid is measured by measuring the speed at which the weight 3 moves up and down. It has become possible. The viscosity of the liquid is measured using such an in-line viscometer 1, and the liquid adjusted to an appropriate viscosity is applied from a die coater.

[0004]

Most of the liquid applied by the above-mentioned die coater is a polymer solution or a dispersion of fine particles. In such a liquid, the form of the polymer and the state of condensation and dispersion of the fine particles change depending on the shear rate. Therefore, the viscosity generally changes depending on the shear rate.

When the relationship between the shear rate and the viscosity is displayed in a log-logarithmic graph, the viscosity often decreases linearly with an increase in the shear rate. When this is expressed by an equation, η = η ₀ · γ ^n-1 where η is the apparent viscosity, η ₀ is the _zero shear viscosity, γ
Is a shear rate, and n is a power law index (power law index), and this relationship is called power law (power law).

Here, the die head is provided with a manifold for feeding the liquid in the width direction and a slit provided from the side of the manifold toward the coating substrate in order to uniformly supply the coating liquid in the coating width direction. Have. The supply of the liquid to the manifold is performed by a pipe connected to the center or the end of the manifold and a pump provided in the pipe. This manifold has a relatively low shear rate, so it has a large apparent viscosity, and there is a risk of pressure drop due to viscous resistance at the distant part of the liquid supply pipe to the manifold, which may cause a decrease in the amount of discharge from the slit. There is.

[0007] The degree of reduction in the discharge amount from the slit in a portion away from the liquid supply pipe to the manifold greatly changes depending on the flow characteristics of the liquid and the internal shape of the die head. As for process control, it is desirable to check the flow characteristics of the liquid before sending the liquid to the die head, which is troublesome for disassembly cleaning and mounting adjustment, and to confirm whether the uniformity in the coating width direction is below a certain limit.

A formula for obtaining the uniformity in the width direction from the flow characteristics of a liquid has been published by Carley. In order to determine the uniformity in the width direction using this equation, the values of the manifold diameter, the slit length, and the gap of the die are determined by Carle.
The power law index and the zero shear viscosity are obtained by substituting into the equation of y.

Here, many conventional in-line viscometers do not have a structure in which the viscosity is determined by changing the shear rate in a wide range, so that the power law index cannot be determined with sufficient accuracy. For this reason, when a liquid that can be measured in a wide shear rate range using a principle of a conventional in-line viscometer is used to measure a liquid that complies with the above power law, this liquid enters the slit and at a constant shear rate. Even when the flow is started, the apparent viscosity does not instantly settle down to a certain value, and the viscosity in the slit flow direction is different, so that the measurement becomes insufficient.

The present invention has been made based on the above circumstances, and has as its object to provide a function for calculating uniformity in a coating width direction and to provide a power law index for calculation with sufficient accuracy. It is an object of the present invention to provide an in-line viscometer, a die coater, and a viscosity control method which can be obtained by the following method.

[0011]

In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that at least two or more conducting portions having flow portions of different sizes are provided,
Pressure measurement means arranged before and after the circulation part to measure the pressure of the liquid before and after the circulation part, and flow rate measurement means to measure the flow rate of the liquid introduced into each circulation part, characterized by comprising This is an in-line viscometer.

According to a second aspect of the present invention, there is provided a die coater including the in-line viscometer according to the first aspect and a die head having a slit and a manifold formed therein, wherein the flow portion is formed corresponding to the slit. A die coater comprising: a slit-equivalent tube portion formed; and a manifold-equivalent tube portion formed corresponding to the manifold.

According to a third aspect of the present invention, the die coater includes control means for controlling a supply amount of a liquid to a die head based on a measurement result of the pipe equivalent to the slit and the pipe equivalent to the manifold. A die coater according to claim 2, wherein

According to a fourth aspect of the present invention, an inlet side of a flow section comprising a slit-equivalent pipe formed corresponding to the slit of the die head and a manifold-equivalent pipe formed corresponding to the manifold of the die head. A pressure measurement step for determining the pressure of the liquid at the outlet side, a flow measurement step for determining the flow rate of the liquid introduced into each flow part, and a slit and a manifold from the values obtained by the pressure measurement step and the flow measurement step. A uniformity calculation step of calculating the uniformity of the liquid discharge amount in the longitudinal direction of the manifold of the die head in which is formed.

According to a fifth aspect of the present invention, there is provided a zero shear viscosity calculating step for obtaining a zero shear viscosity from the values obtained in the pressure measuring step and the flow rate measuring step, and a power calculation based on the values obtained in the pressure measuring step and the flow rate measuring step. A power law index calculating step for obtaining a law index, and a uniformity calculating step for calculating the uniformity of the liquid discharge amount in the longitudinal direction of the manifold based on the zero shear viscosity and the power law index, characterized by comprising: Claim 4
It is a viscosity control method described.

The invention according to claim 6 displays the zero shear viscosity, the power law index, and the uniformity of the calculated liquid discharge amount obtained in the zero shear viscosity calculation step, the power law index calculation step, and the apparent viscosity calculation step. 6. The method according to claim 5, further comprising the step of:

According to the first aspect of the present invention, a zero-shear viscosity and a power law index can be determined by measuring a pressure difference before and after the flow section and then determining a flow rate. For this reason, the viscosity management of the liquid in the non-Newtonian fluid can be realized.

According to the second aspect of the present invention, it is possible to accurately measure a portion of the die head corresponding to the slit and the manifold by using an in-line viscometer. Can be uniformly discharged without variation in the discharge amount.

According to the third aspect of the present invention, it is possible to control the supply amount of the liquid to the die head based on the measurement result, thereby preventing the object to be coated from being wasted, and reducing the cost.

According to the fourth aspect of the present invention, the pressure of the liquid at the inlet side and the outlet side of the conducting section is measured to measure the differential pressure, the flow rate at the flow section is measured, and the uniformity in the longitudinal direction of the manifold is measured. By calculating, the viscosity of the liquid of the non-Newtonian fluid discharged from the die head can be reliably managed.

According to the fifth aspect of the present invention, if the zero shear viscosity, the power law index and the apparent viscosity are calculated and these values are managed, the properties of the liquid can be maintained satisfactorily and the occurrence of problems can be prevented. According to the sixth aspect of the invention, by displaying the zero shear viscosity, the power law index, and the apparent viscosity, it is possible to more easily manage the properties of the liquid.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a die coater 20 having an in-line viscometer. The die coater 20 has a tank 21 in which a coating liquid is stored.
And a stirrer 22 for keeping the concentration of the coating solution stored in the tank 21 constant and eliminating the variation.

The tank 21 is connected to the pump 2 via a pipe 23.
4 is connected. The coating liquid conducted through the pipe 23 by the pump 24 is a mixed liquid, and is a non-Newtonian fluid whose viscosity changes depending on the flow speed.

The pipe 23 discharged by the pump 24
The coating solution that has progressed inside is introduced into the switching valve 25.
The switching valve 25 adjusts the discharge amount of the coating liquid discharged to the branch pipe 27 that sends the coating liquid to the die head 40 side and the branch pipe 28 that sends the coating liquid to the in-line viscometer 30.

FIG. 2 shows an in-line viscometer 30. The branch pipe 28 is branched into two at the inlet of the in-line viscometer 30 to form inlet pipes 31a and 31b, respectively. Flow control valves 32a and 32b are attached to the introduction pipes 31a and 31b, respectively, so that the amount of the applied coating liquid can be adjusted. The coating liquid that has passed through the flow control valve 32 of one of the introduction pipes 31a is introduced into a manifold equivalent pipe section (flow section) 33.

The manifold-equivalent tube section 33 is formed to have the same inner diameter and length as the manifold of the die head 40 described later. Manifold equivalent tube 3
A pressure gauge 34 for detecting the pressure of the coating solution before and after the manifold-equivalent pipe section 33 is attached near the inlet and the outlet of 3. The pressure gauge 34 makes it possible to detect the pressure difference between the vicinity of the inlet and the outlet of the pipe portion 33 corresponding to the manifold of the coating liquid.

A flow meter 35 is mounted near the outlet of the manifold equivalent pipe section 33. This flow meter 3
5 measures the flow rate of the coating liquid discharged from the above-mentioned manifold-equivalent pipe section 33. Since the flow rate of the coating liquid is usually constant near the inlet and the outlet of the manifold-equivalent pipe section 33, the outlet 5 is used. The flow meter 35 is provided only in the vicinity. In addition, near the outlet of the above-mentioned manifold equivalent pipe portion 33, a configuration having both the pressure gauge 34 and the flow meter 35 may be adopted.

The coating liquid introduced into the other introduction pipe 31b and passing through the flow control valve 32b is introduced into, for example, a slit-equivalent pipe section (flow section) 36 formed inside the rectangular parallelepiped. The slit-equivalent tube portion 36 is formed in a size corresponding to a slit 42 of the die head 40 described later.
For example, the length is 50 mm, the gap is 0.5 mm, and the width is smaller than the slit 42 of the die head 40 and is 50 mm.

A pressure gauge 37 is mounted near the inlet and the outlet of the slit-equivalent tube section 36. With this pressure gauge 37, it is possible to detect the pressure difference before and after the above-mentioned slit-equivalent tube section 36.

A flow meter 38 is mounted near the outlet of the above-mentioned slit-equivalent tube section 36. This flow meter 38
The same as the flow meter 35 described above,
It is provided so as to detect the flow rate of the coating liquid that has passed through.

The coating solution that has passed through the manifold equivalent pipe 33 and the slit equivalent pipe 36 joins the branch pipe 28 again. The branch pipe 28 is connected to the tank 21, and is provided so as to return the measured application liquid to the tank 21 again.

On the other hand, a branch pipe 27 extending from the switching valve 25 is connected to a die head 40. The die head 40 has a manifold 41 formed therein. The manifold 41 is formed so as to extend in a direction orthogonal to the direction in which the coating liquid in the branch pipe 27 travels.

A slit 42 corresponding to the length of the manifold 41 is formed on a side surface extending from the manifold 41 toward the base 50. The slit 42 has a gap shape with a gap of 0.5 mm, for example.

The coating liquid passes through the slits 42 uniformly and can be uniformly applied to the surface of the substrate 50 without variation in the discharge amount. The in-line viscometer 30 and the pump 24 may be connected to control means (not shown). In this case, the discharge amount of the pump 24 is automatically adjusted by the measurement of the in-line viscometer 30. It becomes possible.

The die coater 20 having the above configuration
A method for managing a coating liquid that uniformly discharges the coating liquid to the substrate 50 using the method will be described below with reference to FIG. First, the switching valve 25 is switched to supply the coating liquid to the branch pipe 2.
Flow to the 8 side and supply inside the in-line viscometer 30. The coating liquid is branched and introduced into the introduction pipes 31a and 31b, the flow rate is adjusted by the flow control valves 32, respectively, and introduced into the manifold equivalent pipe 33 and the slit equivalent pipe.

The pressure of the coating solution introduced into the manifold equivalent pipe 33 is measured by the pressure gauge 34 before and after introduction into the manifold equivalent pipe 33. Thereby, the pressure difference between before and after introduction into the manifold equivalent pipe portion 33 can be obtained.

The flow rate of the coating solution having passed through the manifold equivalent pipe section 33 is measured by a flow meter 35. Based on the above measurement in the manifold equivalent pipe section 33, the relationship between the _zero shear viscosity η ₀ and the power law index n is obtained by substituting into the following equation.

[0038]

(Equation 1)

The pressure of the coating liquid introduced into the slit-equivalent tube portion 36 can also be measured by the pressure gauge 37 before and after the introduction into the slit-equivalent tube portion 36, whereby the pressure difference between before and after the introduction of the slit-equivalent tube portion 36 is obtained. Can be obtained.

Then, the flow rate of the coating solution that has passed through the slit-equivalent tube section 36 is measured using a flow meter 38. The relationship between η ₀ and n is obtained by substituting these measurement results into the above _equation (1).

Here, the above-mentioned manifold-equivalent pipe section 33 is used.
Η ₀ , n obtained by the introduction into へ₀ , n are substituted into calculation means such as a personal computer to solve simultaneous equations, and values of η ₀ , n are obtained.

Then, the obtained power law index n is substituted into the following equation, and the value of the discharge ratio UI of the end portion with respect to the center of the manifold equivalent pipe portion 33 is obtained by the above-mentioned calculating means such as a personal computer, and is displayed on a display. indicate.

[0043]

(Equation 2)

In this case, n is desirably in the range of 0.6 to 0.85, and η ₀ is in the range of 10 to 70.
It is desirable to be within the range of [P]. By performing such a measurement, n is determined, and the apparent viscosity can be further determined by power law. Then, after the state of the coating liquid becomes a desired state, the switching valve 25 is switched to supply the coating liquid to the die head 40 side to perform coating. In addition, the switching of the switching valve 25 after the desired state is reached is supplied to the branch pipes 27 and 28 in the same amount, and monitoring is performed by a viscometer in parallel with the application, and the values of η ₀ and n are appropriately controlled. Then, the properties of the coating solution can be kept good.

According to the die coater 20 having such a configuration, the values of η ₀ and n are obtained by measuring the differential pressure by the pressure gauges 34 and 37 and the flow rate by the flow meters 35 and 38, and these values are managed. By doing so, the variation of the discharge amount of the coating liquid from the slit 42 to the substrate 50 does not occur,
It is possible to discharge uniformly.

This makes it possible to reliably control the viscosity of the coating liquid that is a non-Newtonian fluid. Also,
Since the obtained η ₀ and n and the discharge ratio UI are displayed on a screen of, for example, a personal computer, it is possible to more easily manage the viscosity of the coating liquid.

If the degree of discharge of the coating liquid is controlled by a separate control means based on these displayed values, it is possible to reduce the cost without causing waste on the object to be coated.

The embodiment of the present invention has been described above, but the present invention can be variously modified. This is described below. In the above embodiment, the in-line viscometer 30 has a manifold-equivalent pipe section 33.
And a configuration having a slit-equivalent tube portion 36. However, in addition to this, at least two spaces having different sizes and shapes are used, and if a pressure difference and a flow rate are obtained before and after this space, this configuration is used. The size and shape of the space may be any.

[0049]

As described above, according to the above-mentioned invention, the zero shear viscosity and the power law index can be obtained by measuring the pressure before and after the conducting part and measuring the flow rate of the conducting part. Therefore, the viscosity of the liquid in the non-Newtonian fluid can be controlled, and the liquid can be discharged uniformly from the slits without variation in the discharge amount.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a configuration of a die coater according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of an in-line viscometer according to the embodiment.

FIG. 3 is a view showing a flowchart for displaying zero shear viscosity, power law index, and discharge amount variation from a pressure difference and a flow rate according to the embodiment;

FIG. 4 is a side sectional view showing a configuration of a conventional in-line viscometer, in which (a) shows a state before the weight is lowered, and (b) shows a state after the weight is lowered.

[Explanation of symbols]

 Reference Signs List 20 die coater 21 tank 23 pipe 27, 28 branch pipe 30 in-line viscometer 33, manifold equivalent pipe part 34, 37 pressure gauge 35, 38 flow meter 40 die head 41 manifold 42 slit 50 base Lumber

Claims (6)

[Claims] 1. At least two or more conducting portions each having a flow portion having a different size, and pressure measuring means disposed before and after the flow portion to measure the pressure of the liquid before and after the flow portion, An in-line viscometer, comprising: flow rate measuring means for measuring a flow rate of a liquid introduced into each flow section. 2. A die coater comprising the in-line viscometer according to claim 1 and a die head provided with a slit and a manifold, wherein the flow portion is a slit-equivalent tube formed corresponding to the slit. And a manifold-equivalent tube formed corresponding to the manifold. 3. The die coater according to claim 2, further comprising control means for controlling a supply amount of a liquid to a die head based on a measurement result of the pipe corresponding to the slit and the pipe corresponding to the manifold. Die coater as described. 4. The flow of liquid on the inlet side and the outlet side of a flow section composed of a pipe equivalent to a slit formed corresponding to a slit of a die head and a pipe equivalent to a manifold formed corresponding to a manifold of a die head. A pressure measurement step for obtaining pressure, a flow measurement step for obtaining a flow rate of the liquid introduced into each of the flow sections, and a die head having a slit and a manifold formed from the values obtained in the pressure measurement step and the flow measurement step. A uniformity calculating step of calculating the uniformity of the liquid discharge amount in the longitudinal direction of the manifold. 5. A zero shear viscosity calculation step for obtaining a zero shear viscosity from values obtained in the pressure measurement step and the flow rate measurement step, and a power law index for obtaining a power law index from the values similarly obtained in the pressure measurement step and the flow rate measurement step. An index calculating step, and a uniformity calculating step of calculating a uniformity of a discharge amount of the liquid in a longitudinal direction of the manifold based on the zero shear viscosity and the power law index. Viscosity control method. 6. A display step of displaying the zero shear viscosity, the power law index, and the calculated uniformity of the liquid discharge amount obtained in the zero shear viscosity calculating step, the power law index calculating step, and the apparent viscosity calculating step. The method for controlling viscosity according to claim 5, wherein