JP2010259986A - Coating method and coater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control unevenness of application due to changes of the solid concentration through application in forming a coating film. <P>SOLUTION: Stable formation of a coating film without the occurrence of unevenness of application due to time-lapse changes of the solid concentration and/or the particle size of an application solution can be carried out by measuring the concentration and particle size of the application solution with a concentration meter 103 and controlling the thickness of application and the dispersion conditions of particles by using the resultant measurements. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a coating method and a coating apparatus for forming a coating film by coating a coating solution.

  In recent years, the demand for optical films and flat displays is increasing. Typical examples of the optical film and the flat display panel include an optical compensation film used as a retardation plate for a liquid crystal cell, a film having various functions such as an antireflection film and an antiglare film, and a flat display panel. .

  As a typical method for producing such an optical film, a coating liquid is applied to the surface of a traveling belt-like flexible support with a coating device, and dried to form coating films of various compositions. A method is mentioned.

  As a typical flat display panel manufacturing method, a coating liquid is applied to the surface of a traveling glass panel by a coating apparatus or the coating head of the coating apparatus applies a coating liquid on the surface of a fixed glass panel. There is a method of running while coating and drying this to form coating films of various compositions.

  As the coating device, the entire amount of the coating solution is applied on the traveling support, for example, the slit die coating device or the coating solution is scraped up from the liquid reservoir and applied to the support, and the excess that has not been applied. There are a comma coating device, a bar coating device, a gravure coating device, a roll coating device, and the like, in which the coating solution is collected and fed again to the coating device.

  In recent years, the required accuracy of thinning the coating film and preventing unevenness in film thickness has become much higher than before due to the high performance of optical films and flat display panels. For this reason, it cannot be solved simply by increasing the mechanical accuracy of the coating device, but the solid content concentration and particle size in the coating solution during the coating process are managed accurately over time. Grain size is becoming important.

  Conventionally, as shown in Patent Document 1, a method of measuring the density of a coating liquid to obtain a difference from a target density and feedback controlling the density of the coating liquid based on the density difference is presented as management of the coating liquid. Has been.

FIG. 6 is a diagram showing a configuration of a conventional coating apparatus described in Patent Document 1. As shown in FIG.
In FIG. 6, the density of the coating liquid in the supply tank 1 is measured, and the density difference between the measured density and a predetermined target density is calculated by the calculating means 2 for density adjustment with an accuracy one digit coarser than the target density The density of the coating liquid flowing through the liquid feeding pipe 5 can be measured in-line after the first density adjusting means for opening and closing the valve 4 piped to the density adjusting station tank 3 containing the liquid and adding the density adjusting liquid. In-line measurement is performed with the density meter 6, and the density difference between the measured density and the predetermined target density is calculated with the calculation means 7, and the density adjustment is performed in the liquid feeding pipe 5 upstream of the density measurement position so that the density difference is eliminated. The application liquid is automatically added using the pump 8 and applied at a constant solid content concentration by a second density adjustment step in which the density of the application liquid is adjusted by feedback control.

JP 2008-173587 A

  Typical coating devices used in the production of optical films include comma coating devices, bar coating devices (bar method, Meyer bar method), gravure coating devices (direct method, kiss method), and roll coating devices. Since these coating apparatuses are a system in which the coating liquid is scraped up from the liquid reservoir and applied to the support, there is a problem that the organic solvent in the coating liquid tends to evaporate. Moreover, in the case of these coating apparatuses, the excess coating liquid which was not apply | coated to a web (support body) is collect | recovered, and the collect | recovered coating liquid is returned to the liquid feeding line which sends liquid to a coating apparatus. It is usually reused. When the coating solution is reused in this way, the coating solution is exposed to the atmosphere when the coating solution is collected, and the organic solvent in the coating solution evaporates, and the solid content concentration in the coating solution is more likely to change. There is.

Therefore, in recent years, a slit die coating apparatus is often used from the tank to the coating head part where the coating solution is difficult to touch the atmosphere.
Furthermore, when manufacturing many optical films and flat display panels, it is often the case that the powder is dispersed in the coating liquid, and the powder often agglomerates with time. In many cases, the density is higher than the solvent of the coating solution, and the powder settles when the coating solution is stationary.

  In any case, in order to keep the optical characteristics constant in the optical film or flat display panel, the weight per unit area and particle distribution of the powder applied and dried on the film or glass substrate should be constant. is required.

  The present invention has been made in view of such circumstances, and an object of the present invention is to suppress coating unevenness due to a change in solid content concentration during coating during the formation of a coating film.

  In order to achieve the above-mentioned object, the coating method of the present invention, when a coating liquid fed from a supply tank via a liquid feeding pipe is applied from a coating nozzle on a traveling support to form a thin film, A step of measuring in-line the concentration and particle size of the coating solution in the middle of the liquid supply pipe, a step of calculating a concentration difference between the measured concentration and a predetermined target concentration, and the coating solution according to the concentration difference A step of feedback controlling the flow rate, a step of calculating a particle size difference between the measured particle size and a predetermined target particle size, and a step of feedback controlling the dispersion state of the coating liquid in the supply tank according to the particle size difference It is characterized by having.

  The coating apparatus of the present invention is a coating apparatus that forms a thin film by coating a coating liquid fed from a supply tank via a liquid feeding pipe from a coating nozzle onto a traveling support, and the liquid feeding pipe A concentration meter for measuring the concentration of the coating liquid in-line, a concentration calculator for calculating a concentration difference between the measured concentration and a predetermined target concentration and controlling the flow rate of the coating solution, and the concentration calculation And a metering pump for adjusting the flow rate by controlling the vessel.

  In addition, a coating apparatus that forms a thin film by applying a coating liquid fed from a supply tank via a liquid feeding pipe from a coating nozzle onto a traveling support, and the coating liquid is formed in the middle of the liquid feeding pipe. A concentration meter that measures the concentration of the coating liquid in-line, and a particle size calculator that controls a dispersion state of the coating liquid in the supply tank by calculating a particle size difference between a particle size obtained from the measured concentration and a predetermined target particle size; And a dispersing device for dispersing the coating liquid in the supply tank under the control of the particle size calculator.

  In addition, a coating apparatus that forms a thin film by applying a coating liquid fed from a supply tank via a liquid feeding pipe from a coating nozzle onto a traveling support, and the coating liquid is formed in the middle of the liquid feeding pipe. A concentration meter that measures the concentration of the coating solution in-line, a concentration calculator that controls a flow rate of the coating liquid by calculating a concentration difference between the measured concentration and a predetermined target concentration, and is controlled by the concentration calculator. A metering pump for adjusting the flow rate, a particle size calculator for controlling a dispersion state of the coating liquid in the supply tank by calculating a particle size difference between a particle size obtained from the measured concentration and a predetermined target particle size, And a disperser that disperses the coating liquid in the supply tank under the control of a particle size calculator.

Further, a thermometer is provided in the supply tank, and the temperature of the densitometer is corrected.
Moreover, it has further a liquid feeding pump which circulates the said coating liquid at a predetermined space | interval in the state which covered the said coating nozzle at the time of application | coating stop.

Further, the densitometer is an optical densitometer.
The optical densitometer includes a light emitting unit that irradiates the coating liquid with light, a light receiving unit that receives the light transmitted or reflected through the coating liquid, a light guide path glass through which the light passes, and the light And a light-shielding layer formed around the light guide glass by opening the irradiation and emission positions.

The coating liquid is a coating liquid in which powder is dispersed.
As described above, it is possible to suppress coating unevenness due to a change in solid content concentration during coating during the formation of the coating film.

  As described above, according to the present invention, the concentration and particle size of the coating liquid are measured, and the measurement result is used to control the coating thickness and the dispersion state of the particles. A stable coating film can be formed without causing coating unevenness resulting from changes over time.

The figure for demonstrating the structure of the coating device of this invention The figure for demonstrating the structure of the coating device at the time of circulation operation | movement Sectional view showing the configuration of the densitometer Sectional drawing which shows the structure of the concentration meter which formed the pipe line with the hose The figure which illustrates the output result of the densitometer The figure which shows the structure of the conventional coating device

  In the conventional adjustment of the solid content of the coating solution by simple feedback control, which adds the solvent of the coating solution to the volatilized coating solution, a super-precise coating solution is used, such as coating to produce a film on a film or glass substrate. Even if the solid content concentration can be controlled, the dispersion state often changes, and the optical properties of the coating film on the coated and dried film or glass substrate are not always constant, and the same optical properties are obtained. Can't get.

  Therefore, as a result of extensive research, the inventor has determined that the feed flow rate feedback control of the metering pump at the time of application so as to eliminate the concentration difference between the measured concentration measured in-line and the target concentration in the liquid feeding pipe from the tank to the coating device. It was found that the optical properties of the coating film on the coated and dried film and the glass substrate can be made constant by finely adjusting the wet film thickness and making the particle size constant by using a dispersion means for the coating liquid.

  As described above, the present invention is characterized by the adjustment of the particle size in the tank that can easily adjust the particle size of a large amount of coating solution to a certain level of accuracy in a short time, and the concentration is highly accurate when the solvent in the coating solution is volatilized. By combining and combining the characteristics of concentration measurement in the middle of the liquid supply pipe that facilitates in-line measurement and the feedback function of wet film thickness according to the concentration and particle size, on the coated and dried film or glass substrate The optical properties of the upper coating can be made constant. Even a minute solid concentration change in the coating solution that does not appear as a change in the viscosity of the coating solution can be detected with high accuracy and in real time by detecting the concentration of the coating solution. Moreover, the thickness of the wet film thickness is calculated from the density difference between the measured density measured and the target density defined in advance. The density can be fed back to the film thickness regardless of whether the density is higher or lower than the target density. The target concentration is a concentration originally defined when preparing the coating liquid, and refers to a concentration corresponding to the target solid content concentration.

  Hereinafter, preferred embodiments of a coating liquid coating method and a coating apparatus according to the present invention, and an optical film and a flat display panel manufactured using the coating apparatus according to the present invention will be described in detail with reference to FIGS. Here, as a typical explanation, a flat display panel is taken as an example.

  FIG. 1 is a diagram for explaining a configuration of a coating apparatus according to the present invention, and is an explanatory diagram for explaining a coating liquid coating method according to the present invention and a flat display panel manufacturing line to which the coating apparatus is applied. FIG. 2 is a diagram for explaining the configuration of the coating apparatus during the circulation operation. FIG. 3 is a cross-sectional view showing the configuration of the densitometer, and FIG. 4 is a cross-sectional view showing the configuration of the densitometer in which a pipe line is formed by a hose. FIG. 5 is a diagram illustrating the output result of the densitometer.

  As shown in FIG. 1, the flat display panel production line uses an optical densitometer 103 to measure the concentration and particle size of the coating liquid fed from the tank 101 filled with the coating liquid to the coating apparatus via the liquid feeding pipe. The flow rate calculated from the results is controlled by the metering pump 104, and applied to the glass substrate 106 temporarily fixed on the traveling stage 107 through the application nozzle 105 and intermittently applied. This is a coating method in which the coating liquid is circulated using the liquid feeding pump 102 after sealing the tip of the coating nozzle for the purpose of preventing sedimentation of particles in the liquid and cleaning the densitometer.

  Here, even when the coating nozzle 105 is stationary and the stage 107 is traveling, even when the coating nozzle 105 is traveling on the stage 107 and the stage 107 is stationary, the coating thickness can be adjusted by adjusting the flow rate of the metering pump 104. The present invention can be used when the configuration can be changed. The coating nozzle 105 indicates a slit die. The slit die distributes the coating solution supplied from the pipe uniformly in the width direction in a groove called a manifold, and the coating solution is applied to the glass substrate so that the coating thickness is uniform in the width direction from the slit part provided at the tip. This is a mold that can be applied to 106.

If there is no problem in accuracy, stainless steel, ceramics, glass, resin such as PEEK and PAI, etc. can be used as the material of the slit die.
As the coating solution, one containing glass powder, binder, plasticizer, and solvent containing at least one component of PbO, MgO, B ₂ O ₃ , SiO ₂ and CaO is used.

  The concentration feedback control mechanism 111 mainly calculates the concentration difference between the concentration meter 103 that measures the concentration of the coating liquid flowing in the pipe in-line and the measured concentration measured in advance and the predetermined target concentration of the coating solution. The concentration difference is fed back to the metering pump 104 so that there is no difference in the optical characteristics of the coating film on the glass substrate 106 after drying by the above, and the flow rate of the coating liquid applied through the application nozzle 105 is adjusted so as to eliminate the concentration difference. It consists of a density calculator to adjust. The metering pump here is preferably a metering pump such as a plunger pump, a diaphragm pump, or a gear pump.

  When performing density feedback, the current density detected by the densitometer 103 is compared with the target density, and an excess or deficiency in film thickness is predicted based on the measured density value, and adjustment is made to achieve a predetermined film thickness. To do. That is, if the current concentration is lower than the target concentration, it is determined that the film thickness is insufficient, and the flow rate of liquid delivered by the metering pump is increased, and if the current concentration is higher than the target concentration, the film thickness is determined to be too thick. And reduce the flow rate of liquid delivered by the metering pump. In the case of a coating method called a roll-to-roll, in which a hoop-shaped substrate runs between the unwinding portion and the winding portion and is coated on the substrate, feedback is performed sequentially, but a square or circular substrate In the single-wafer coating in which each is coated, feedback is performed after the coating of one sheet is completed. That is, no feedback is performed because the in-plane film thickness distribution deteriorates during the period from the start of application to the end of application.

  The particle size feedback control mechanism 112 includes an optical densitometer 103 and a dispersion unit 108. The particle size feedback control mechanism 112 calculates the difference between the particle size measured by the optical densitometer 103 and the target particle size, and the dispersion unit 108 calculates the difference from the calculated value. The output is adjusted and the dispersion state of the coating liquid is kept constant. The dispersing means 108 here is preferably a dispersing means such as a rotary motion such as a disperser / propeller and ultrasonic vibration.

  When performing particle size feedback, the current particle size detected by the densitometer 103 is compared with the target particle size, and a value is output to the dispersion means. In other words, if the current particle size is larger than the target particle size, it is judged that the particles in the coating liquid are condensed, and the rotation speed of the dispersing means and the output of the ultrasonic wave are increased. If the current particle size is smaller than the target particle size, It is judged that the particles in the coating liquid are excessively dispersed, and the rotational speed of the dispersing means and the output of the ultrasonic wave are lowered or stopped. In many cases, the dispersion means is continuously dispersed and the viscosity is lowered when the high-speed rotation is continued. In the former case, the characteristics may be adversely affected. In the latter case, precipitation due to a decrease in viscosity may proceed. As for the rotational speed, it is desirable that the rotational speed is low enough that the concentration distribution due to sedimentation in the tank can be suppressed and the particle size and viscosity are not significantly reduced.

  Further, as shown in FIG. 1, a thermometer 113 for measuring the temperature can be provided on the side wall of the tank 101. When the thermometer 113 is provided, the measured temperature of the coating liquid is supplied to the calculation means. Temperature correction is performed on the concentration that is sequentially input and measured by the densitometer 103.

  The optical densitometer 103 includes a light receiving unit, a light emitting unit, and an arithmetic circuit that calculates an output value thereof. Light sources such as infrared lasers, visible light lasers, ultraviolet lasers, and X-ray lasers, lamp light sources such as tungsten lamps and xenon lamps, and light emitting diodes such as red light emitting diodes and blue light emitting diodes can be used. As the detection element, a photodiode using a material such as silicon, germanium, indium / gallium / arsenic, or lead sulfide can be used.

The arithmetic circuit performs the calculation using the following measurement method. As an explanation of the measurement method, an example using infrared rays is described, but depending on the properties of the coating liquid, visible light and ultraviolet light can be detected better, so after examining the wavelength characteristics, the light emitting part and light receiving part It is desirable to select materials.
(Explanation of measurement method)
(Measurement of concentration)
The measurement of the concentration τ in the optical densitometer 103 is performed by irradiating the coating liquid circulated in the pipe with infrared rays (wavelength: 900 nm), and using the following formula (from the incident light of the light emitting part and the transmitted light of the light receiving part) Calculated from 1).
τ = −ln (It / I0) / L (Lambert's formula) (1)
(However, I0 is the incident light intensity, It is the transmitted light intensity, It / I0 is the light intensity ratio before and after transmission of the coating solution, and L is the depth of the paste, and the value is not particularly limited.)
In the above equation, (It / IO) increases, that is, when the coating solution is thin, the output value decreases, and conversely, when the coating solution is thick, the output value increases.

  Further, the temperature of the coating solution at the time of concentration measurement is not particularly limited, but generally, the higher the temperature, the worse the dispersion stability of the coating solution and the turbidity tends to increase. Therefore, the temperature should be measured at 10 to 40 ° C, more preferably 10 to 25 ° C.

  In addition, about the powder used as a measuring object, a particle size exists in the range of 0.8 nm-1 mm, and the solvent component and refractive index should just differ from a coating liquid. Regarding the color, even if the color is the same as that of the transparent body or the solvent, it is only necessary to detect the refractive index difference between the solvent and the powder component by changing the wavelength. However, since it cannot be used in a state where the light emitted from the light emitting unit is completely blocked and does not reach the light receiving unit, in that case, the distance between the light emitting unit and the light receiving unit to the distance at which the light receiving unit can detect the light of the light emitting unit. It is desirable to reduce

  FIG. 2 shows an operation state during circulation that is intermittently performed. The application nozzle 105 is raised, the seal unit 115 having the rubber seal 114 is moved below the tip of the application nozzle, and then the application nozzle 105 is lowered and applied. The discharge port at the tip of the nozzle 105 is blocked.

  After the blockage, the coating liquid in the tank 101 is supplied to the coating nozzle by the liquid feed pump 102 and returned to the tank 101 through the return pipe 116, so that the coating liquid in the tank-coating nozzle-return pipe is settled. In addition, the detection unit of the densitometer 103 can be cleaned.

  The circulation operation depends on the viscosity of the coating solution, the specific gravity difference between the powder in the coating solution and the solvent of the coating solution, the pipe diameter, and the reference concentration of the coating solution. This may be performed when the current density becomes a predetermined difference with respect to the density, or may be performed at regular intervals.

Further, when a large particle size difference is observed in the coating solution, it is preferable to perform the particle size feedback control during the circulation operation.
As a circulation flow rate, in a pipeline having a viscosity of 20 mPa · s or less and a pipe diameter of 3/8 to 1 inch, it is preferable to circulate for a period of time such that the inside of the pipeline is replaced three times at a flow rate of 3 L / min or more. .

  FIG. 3 is a detailed view of the densitometer 103. A light emitting unit 120 and a light receiving unit 121 are provided on both sides of a pipe 124 through which a coating solution passes, and a light guide glass 123 made of glass or resin is provided so as not to be in direct contact with liquid. The densitometer 103 is held by the casing 122 that constitutes the conduit 124. In order to perform high-precision concentration measurement, irregular reflection from the surroundings can be suppressed by forming a uniform light-shielding layer 125 such as aluminum vapor deposition on the peripheral part (cylindrical part) other than the optical path of the light guide glass 123. It is possible to detect the concentration and the particle size with high accuracy without being affected by the temporal change caused by the particles adhering between the casing 122 and the light guide glass 123 over time. Here, the configuration in which transmitted light is received by the light receiving unit 121 is shown, but the light receiving unit 121 may be configured to receive reflected light from the coating liquid.

  In addition, when the particles adhere to the light guide glass 123 and grow, the fluorine resin such as PFA, PTFE, PVDF, FEP, PCTFE, ETFE, ECTFE, or the like, or the polymer such as PP, PET, PE is difficult to adhere. The light guide glass 123 may be made of a thin resin and made light transmissive.

  As shown in FIG. 4, when the pipe 124 is formed using a fluororesin and a polymer resin hose without using a casing, the light guide glass is not used and a pair of half brackets 126 are attached. The light emitting unit 120 and the light receiving unit 121 may be provided, and the hose 127 forming the pipe 124 may be sandwiched and fastened with bolts, screws, magnetic force, or the like.

  In this case, it can be manufactured at a lower cost than the embodiment of FIG. 3, but since the distance between the light emitting part and the light receiving part is limited by the inner diameter of the hose, concentration can be detected, but detection of highly sensitive particles becomes difficult. There is a thing.

The coating apparatus 110 of the present invention can manage changes in solid content concentration and particle size in the coating liquid that do not appear as viscosity changes in the production of optical films and flat display panels that require strict optical performance. Therefore, it is preferable to use an optical densitometer.
(Measurement of particle size)
Hereinafter, the measurement method of the particle size will be described with reference to FIGS. 5, 1, and 3, and waveform data obtained based on the output equation (1) used in the densitometer 103 is FIG. 5. As an output value, the amount of light reaching the detection element of the light receiving unit 121 from the light source of the light emitting unit 120 via the coating liquid (and the casing 122 or the hose 127) is converted into voltage or current using a photodiode, and further, Conversion is performed by performing the calculation of equation (1) (in this description, voltage). In FIG. 5, the average of the output values for a certain period is the density average value 150, which decreases when the density becomes light and increases when the density becomes dark.

Further, the concentration average value indicates the average particle size of the coating liquid passing through the pipe 124, and a large signal 151 partially showing a high output with respect to the concentration average value measures particles larger than the average particle size. The rising period 152 indicates the particle size, and the particle size can be calculated by the product of the flow rate in the pipe and the time of the period. When the output value increases in a short time like the slightly larger particle signal 153, the particle is larger than the average particle size but relatively small. What partially shows a low signal 154 with respect to the concentration average value is a signal when measuring particles or bubbles smaller than the average particle diameter. This output fluctuation can be calculated for each particle within a certain period, and the frequency can be calculated to calculate the particle size distribution. Depending on the output, the dispersion means output can be changed to change the output in the coating solution. The distribution of particles can be made uniform.
(Example of particle size measurement)
Examples of particle size measurement are shown below.

A coating liquid having the same configuration as that shown in FIG. 1 and containing a glass powder containing at least one of PbO, MgO, B ₂ O ₃ , SiO ₂ and CaO, a binder, a plasticizer, and a solvent. Using.

The concentration of the coating solution was 1 wt% and the average particle size in the coating solution was 3 μm.
Using a coating nozzle having a coating width of 1000 mm, a section having a length of 560 mm was coated on a glass substrate with a coating thickness of 20 μm at a coating speed of 30 mm / s. After coating, it is dried using a vacuum drying device, and the coating area is inspected in 9 divisions of length 3 × width 3, and in accordance with JISK7165: 1981, a haze meter (“NDH2000”, Nippon Denshoku Industries Co., Ltd.) Manufactured or equivalent model) using a D65 light source.

In addition, the coating test was performed 500 sheets, and the particle size within the range of ± 5% from the reference value was determined as ◯, and the one out of the range was determined as ×.
(Comparative experiment)
As a comparative example, the case where only the density feedback function is not functioned is set as Comparative Example 1, the case where both the density feedback function and the granularity feedback function are not functioned is set as Comparative Example 2, and the other examples are the same. Application was performed under conditions.

  Here, the comparison result between the example and the comparative example is shown in Table 1, and the comparison is made by the number of sheets corresponding to the determination result.

  In the case of Example, a defect due to the occurrence of defects other than coating unevenness occurred, whereas in the case of Comparative Example 1 in which only concentration feedback is not performed, the concentration of the coating liquid proceeds more than half of the latter half of the coating, thereby increasing the concentration. Since the coating amount decreased and the coating amount decreased, the coating result out of the range increased. Furthermore, in the case of Comparative Example 2 in which both the concentration feedback function and the particle size feedback function are not functioned, the dispersion state of the particles deteriorates with time, and the settling speed is increased by further agglomeration. The decrease was remarkable and the results of coating out of the range were further increased.

  In this way, the film thickness can be kept constant by measuring the concentration of the coating liquid in the coating apparatus inline, and by controlling the flow rate of the coating liquid by the concentration feedback control according to the difference between the measured concentration and the target concentration, Uneven coating can be prevented and stable characteristics can be ensured. At the same time or separately, the particle size of the coating solution in the coating device is measured in-line, and the dispersion state of the coating solution is feedback-controlled by the difference between the measured particle size and the target particle size. Since it can be kept constant, changes in solid concentration and sedimentation of particles can be suppressed, coating unevenness can be prevented, and stable characteristics can be ensured. In addition to these controls, the coating liquid is circulated at a predetermined interval while the application is stopped, so that the sedimentation of particles can be prevented and the densitometer can be cleaned, so feedback control can be performed with higher accuracy. It is possible to prevent coating unevenness and secure more stable characteristics.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Various aspects, such as the coating method of the roll to roll represented by the coating method of an optical film, can be taken. Further, as the coating liquid, powder may be dispersed, or a coating liquid to which no powder is added may be used. For example, as a coating solution to which no powder is added, a coating solution in which an emulsion resin such as acrylic, acrylic / styrene, vinyl acetate, EVA, fluorine, or urethane is dispersed can be used.

  INDUSTRIAL APPLICABILITY The present invention can suppress coating unevenness due to a change in solid content concentration during coating when forming a thin film, and is useful for a coating method and a coating apparatus that form a thin film by coating a coating solution.

DESCRIPTION OF SYMBOLS 1 ... Tank, 2 ... Calculation means, 3 ... Density adjustment liquid tank, 4 ... Valve, 5 ... Liquid supply piping, 6 ... Density meter, 7 ... Calculation means 8 ... Pump 101 ... Tank, 102 ... Liquid feed pump, 103 ... Densitometer, 104 ... Metering pump, 105 ... Application nozzle, 106 ... Glass substrate, 107 ... Stage, 108 ..Dispersion means, 110... Coating device, 111... Density feedback control mechanism, 112 .granularity feedback control mechanism, 113 .. thermometer 114 .. rubber seal, 115. ... light emitting part, 121 ... light receiving part, 122 ... casing, 123 ... light guide glass, 124 ... pipe,
125 ... light shielding layer, 126 ... bracket, 127 ... hose 150 ... concentration average value, 151 ... signal of large particles, 152 ... period representing the size of particles,
153 ... Slightly large particle signal, 154 ... Signal

Claims (9)

When applying the coating liquid fed from the supply tank via the liquid feeding pipe to the traveling support from the coating nozzle to form a thin film,
A step of measuring in-line the concentration and particle size of the coating liquid in the middle of the liquid feeding pipe;
Calculating a concentration difference between the measured concentration and a predetermined target concentration;
Feedback control of the flow rate of the coating solution according to the concentration difference;
Calculating a particle size difference between the measured particle size and a predetermined target particle size;
And a feedback control of the dispersion state of the coating liquid in the supply tank according to the particle size difference. A coating apparatus that forms a thin film by coating a coating liquid fed from a supply tank via a liquid feeding pipe on a traveling support from a coating nozzle,
A densitometer for measuring the concentration of the coating solution in-line in the middle of the liquid feeding pipe;
A concentration calculator for controlling the flow rate of the coating liquid by calculating a concentration difference between the measured concentration and a predetermined target concentration;
And a metering pump that adjusts the flow rate under the control of the concentration calculator. A coating apparatus that forms a thin film by coating a coating liquid fed from a supply tank via a liquid feeding pipe on a traveling support from a coating nozzle,
A densitometer for measuring the concentration of the coating solution in-line in the middle of the liquid feeding pipe;
A particle size calculator for calculating a particle size difference between a particle size obtained from the measured concentration and a predetermined target particle size to control a dispersion state of the coating liquid in the supply tank;
And a dispersing device for dispersing the coating liquid in the supply tank under the control of the particle size calculator. A coating apparatus that forms a thin film by coating a coating liquid fed from a supply tank via a liquid feeding pipe on a traveling support from a coating nozzle,
A densitometer for measuring the concentration of the coating solution in-line in the middle of the liquid feeding pipe;
A concentration calculator for controlling the flow rate of the coating liquid by calculating a concentration difference between the measured concentration and a predetermined target concentration;
A metering pump that adjusts the flow rate under the control of the concentration calculator;
A particle size calculator for calculating a particle size difference between a particle size obtained from the measured concentration and a predetermined target particle size to control a dispersion state of the coating liquid in the supply tank;
And a dispersing device for dispersing the coating liquid in the supply tank under the control of the particle size calculator.   The thermometer is provided in the said supply tank, The temperature correction of the said concentration meter is performed, The coating device in any one of Claims 2-4 characterized by the above-mentioned.   6. The coating apparatus according to claim 2, further comprising a liquid feed pump that circulates the coating liquid at a predetermined interval in a state where the coating nozzle is covered when the coating is stopped.   The coating apparatus according to claim 2, wherein the densitometer is an optical densitometer. The optical densitometer is
A light emitting unit for irradiating the coating liquid with light;
A light receiving portion for receiving the light transmitted or reflected by the coating liquid;
A light guide glass through which the light passes;
The coating apparatus according to claim 7, further comprising: a light-shielding layer formed around the light guide glass by opening the light irradiation and emission positions.   The coating apparatus according to any one of claims 2 to 8, wherein the coating liquid is a coating liquid in which a powder or an emulsion material is dispersed.

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