JP2000093882A - Application of viscous coating solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily remove bubbles by making the flow velocity of the tip of a coating soln. in a pipe higher than the natural falling flow velocity when liq. supply is started at the part when liq. is supplied downward among the paths supplied with liq. from a defoaming kettle. SOLUTION: When a viscous coating soln. is applied, the previously regulated viscous coating soln. is stored in a storage tank 10 and sent to a defoaming kettle 13 by a pump 11 through a filter 12 when applied to remove the bubbles in the coating soln. The soln. is supplied to a coating device 14 from the kettle 13 through liq. feeding pipes 17 to 19 provided with a pump 15 and a filter 16 in the middle. In this case, a downward pipeline, namely the liq. feed pipe 17 and/or the downward liq. feed part 18a of the pipe 18, is provided to the liq. feed paths from the kettle 13 to filter 16, and then the flow velocity of the head of the viscous coating soln. in the pipe is made higher than the natural falling flow velocity when the soln. supply is started. Consequently, the pipeline is rapidly filled with the coating soln., and the air in the pipeline is prevented from being entrained by the bubbles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to various polymer liquids,
The present invention relates to a method for applying a high-viscosity coating liquid used when a dispersion liquid such as a photosensitive coating liquid, a magnetic powder dispersion liquid, and a phosphor ceramic is coated and dried on a film. The present invention relates to a method for applying a high-viscosity coating solution that can be performed while easily removing bubbles therein.

[0002]

2. Description of the Related Art When forming a thin coating film on a base such as a film, if a coating method contains air bubbles in a coating solution, a pinhole or a coating streak is generated, so that a defective product is generated. turn into. Defoaming tanks are used to remove air bubbles in the coating solution, but air bubbles can also be generated in the liquid supply pipe, so it is not possible to remove air bubbles with the deaerator alone It is.

[0003] Regarding the removal of air bubbles during liquid feeding, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 9-34533 teaches that when a photographic coating solution is guided from a storage tank to a coating device, the coating solution is always sent in an upward flow without creating a state in which the coating solution falls freely. ing.

Japanese Patent Publication No. Sho 62-43722 teaches that degassing is performed by heating and depressurizing treatment.
Japanese Patent No. 265639 teaches that air bubbles in a coating liquid supply pipe are sucked by a vacuum generating means.

[0005]

In order to produce a phosphor, a high-viscosity coating solution in which a phosphor, a resin, a catalyst, and the like are mixed and dispersed is sent to a coater and coated on a film. When air bubbles are generated during the process (1) and the coating is performed until the air bubbles are removed, coating defects such as generation of coating streaks occur. Like the manufacture of phosphors,
When the coating solution has a high viscosity, removal of air bubbles remaining in the coating solution involves more difficulty than in the case of a coating solution having a low viscosity.

The present invention has been made in view of the above, and an object of the present invention is to clarify a method of applying a high-viscosity coating solution that can easily remove bubbles.

[0007]

According to the present invention, there is provided a method of applying a high-viscosity coating solution, which is performed at the time of starting the feeding of a liquid in a downward direction in a path fed from a defoaming tank. It is characterized in that the flow velocity in the pipe at the liquid tip is higher than the natural flow velocity.

[0008]

FIG. 1 is a schematic view showing one embodiment of a method for applying a high-viscosity coating solution according to the present invention, and the arrangement of members is as follows. The high-viscosity coating solution adjusted by a mechanism / device (not shown) is stored in a storage tank 10 and is prepared. At the time of coating, first, a pump 11 is driven to be sent to a defoaming tank 13 via a filter 12 by a drive,
Defoaming of bubbles in the coating solution is performed. The liquid is sent from the defoaming tank 13 to the coating device 14 by supply pipes 17, 18, and 19 in which a pump 15 and a filter 16 are arranged on the way.

The method for applying a high-viscosity coating liquid according to the present invention is characterized by the arrangement of the liquid feed pipes 17 to 19 and the flow velocity in the pipes. The feature is that, first, a downward pipe section is provided in a liquid feeding path that is continuous from the defoaming tank 13 and a liquid feeding path that sandwiches the filter 16. In the illustrated embodiment, the liquid feed path continuous from the defoaming tank 13 corresponds to the liquid feed pipe 17 and the downward liquid feed section 18a of the liquid feed pipe 18. Filter 16
In the illustrated embodiment, the liquid feed path sandwiching is the upward liquid feed section 18b of the liquid feed pipe 18 and the upward liquid feed section 19a of the liquid feed pipe 19.

A characteristic related to the flow rate in the pipe is that a portion of the liquid sent from the defoaming tank 13 to which the liquid is sent downward, in the illustrated embodiment, the liquid feeding pipe 17 and / or the liquid feeding pipe 18. When the high-viscosity coating liquid starts to flow through the directional liquid feeding section 18a, the flow velocity in the pipe at the head of the liquid is set to be higher than the natural flow velocity. The natural flow velocity is not simply determined by the gravitational acceleration, but varies depending on the viscosity of the coating solution, the pipe diameter, and the like. Therefore, the reference natural flow velocity differs when the viscosity of the coating liquid differs.

When the supply of the high-viscosity coating solution from the defoaming tank 13 is started in a state where the high-viscosity coating solution does not exist in the pipe, if the flow rate of the portion which is first sent downward is changed, If the flow rate is lower than the natural flow rate, the inside of the pipe will not be filled with the high-viscosity coating solution, and the air in the pipe will be entrained as bubbles. By setting the flow velocity higher than the natural flow velocity of the high-viscosity coating liquid, the inside of the pipe is rapidly filled with the high-viscosity coating liquid, and the above-described situation is avoided.

The high-viscosity coating liquid refers to a liquid having a viscosity of 50 cp or more, and the present invention is preferably applied to a high-viscosity liquid of 1 p or more. The flow rate that is higher than the spontaneous flow velocity depends on the viscosity of the coating liquid.
Less than double is suitable. If the flow rate exceeds this, the displacement of the air in the tube will also be poor.

Next, in the portion where the filter 16 is disposed, the coating liquid is introduced from the bottom side of the filter housing. With this configuration, the air in the filter housing is discharged upwards in a form in which it is lifted by the high-viscosity coating solution that is introduced from the bottom side and accumulates in the filter housing, so that air entrainment does not occur. .

The defoaming in the defoaming pot 13 is performed by, for example, the defoaming pot 1
Inside 3, the upper surface of the liquid phase is continuously depressurized by a vacuum pump (not shown) to remove air bubbles in the coating solution. At this time, it is preferable to add a configuration that assists the bubbles in the coating liquid to move quickly upward by applying ultrasonic vibration to the coating liquid.

If a general pump is used as the pump 15, the replacement of air and liquid at the start of liquid feeding is not successful, and bubbles are generated in the liquid. Therefore, it is preferable to use a tube pump.

Further, the pressure-feeding solution is constructed by connecting the defoaming vessel 13 to a compressor (a pressurizing source such as a nitrogen cylinder) without using the pump 15 and pressurizing the inside of the defoaming vessel 13. Can also be adopted.

[0017]

Next, the present invention will be described in detail with reference to experimental examples. <Preparation of high-viscosity coating solution> A phosphor solution, a binder, and a solvent are mixed and dispersed to form a coating solution A (viscosity 10p), a coating solution B
(Viscosity 100P) was adjusted.

<Preparation of Comparative Coating Solution> In the same manner as described above, a comparative coating solution A (viscosity: 10 cp) was prepared by mixing and dispersing phosphor particles, a binder, and a solvent.

<Apparatus Used> A pressure liquid feeding method using a defoaming tank as a liquid feeding tank is adopted, and a discharge pipe (tube diameter 20 mm) is provided below the tank.
Was mounted vertically and connected to a coating device via a filter.

EXPERIMENTAL EXAMPLE 1 Using a coating solution A (viscosity 10p) and a coating solution B (viscosity 100p), a defoaming vessel was used so that the flow velocity in the vertical portion of the discharge pipe below the kettle was greater than the natural flow velocity. The liquid was fed by adjusting the flow rate by adjusting the internal pressure, and the solution was applied. As a result, no coating streak was generated by any of the coating liquids, and there was no pinhole, and good coating could be performed.

Experimental Example 2 Coating was carried out in the same manner as in Experimental Example 1, except that the flow velocity in the vertical portion of the discharge pipe below the kettle was smaller than the natural flow velocity. As a result, air could not be replaced with air in the pipe at the beginning of the liquid feeding, and the air and the liquid were mixed, and coating streaks and pinholes occurred frequently with any of the coating liquids, resulting in poor coating. Was.

Experimental Example 3 Coating was carried out in the same manner as in Experimental Example 1, except that a comparative coating solution A having a low viscosity (viscosity 10 cp) was used. Result is,
Since the natural flow velocity was high and the viscosity was low, bubbles were mixed in the coating solution, and coating streaks and pinholes were frequently generated, resulting in poor coating.

Experimental Example 4 Coating was carried out in the same manner as in Experimental Example 2, except that Comparative Coating Solution A having a low viscosity (viscosity 10 cp) was used. Result is,
Application streaks and pinholes occurred frequently, and application was poor.

[0024]

According to the present invention, even with a coating liquid having a high viscosity, the coating can be performed by removing bubbles present in the liquid feed pipe, thereby solving the problems described above. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating one embodiment of the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10-Storage tank 11-Pump 12-Filter 13-Defoaming tank 14-Coating device 15-Pump 16-Filter 17-Liquid supply pipe 18-Liquid supply pipe 18a Liquid supply part 18a downward liquid supply part 18b liquid supply pipe 18 upward liquid feed section 19-liquid feed pipe 19a liquid feed pipe 19 upward liquid feed section

Claims (1)

[Claims] 1. A method of applying a high-viscosity coating liquid, wherein a flow rate in a pipe at a tip portion of the coating liquid at the start of the liquid feeding in a part of the path which is fed downward from a path sent from a defoaming tank. To
A method for applying a high-viscosity coating solution, characterized in that the flow rate is higher than the natural falling flow rate.