JP2003205230A - Tank with agitator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To homogeneously mix and dissolve powders which are easy to float on the liquid surface and is hardly sinked in a liquid even if agitated violently or are easy to precipitate in the liquid in a tank with a simple constitution. <P>SOLUTION: A flat plate-inclined upper paddle 70 and a lower paddle 72 are fit to an agitation shaft 68 in the vertical tank 60 and a baffle plate 64 is fit vertically to the inner wall surface 60A of the tank 60. The position of the top end 64A of the plate 64 is not made higher than that of the paddle 70. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stirring tank,
In particular, the present invention relates to a stirring tank suitable for mixing and dissolving a plurality of types of powders having different characteristics in a dissolution liquid when preparing a coating liquid for producing a film product for photography, magnetic recording media and the like.

[0002]

2. Description of the Related Art In a liquid preparation process for preparing a coating solution for producing film products for photography, magnetic recording media, etc., various powders as raw materials are uniformly mixed and dissolved in a solution such as water. There is a need. At this time, depending on the type of powder, for example, polyvinylpyrrolidone (PVP) is a powder that easily floats on the water surface and is difficult to be caught in water even if stirred, or polyvinyl alcohol (PVA) is used as a powder in water. There are powders that easily form and settle. Therefore, it suffices to mix and dissolve the powder using a dedicated stirring tank for each type of powder according to the characteristics of the powder, but there are many types of powder to be mixed and dissolved. If it is provided, the equipment cost will increase and there will be a problem of installation space.

Therefore, a plurality of kinds of powders having different characteristics are used
In order to uniformly mix and dissolve in one stirring tank, various improvements have been made such as using a stirrer having a different tank shape and stirring method.

[0004]

However, in the conventional stirring tank, particularly when the powder that easily floats on the liquid surface and the powder that easily sediments on the bottom surface of the tank are mixed and dissolved in one tank, they are uniformly mixed and dissolved. However, there is a drawback that some powder remains without being dissolved.

Further, if the shape of the tank or the stirrer becomes complicated, the cleaning property deteriorates, so that there is a drawback that contamination easily occurs when changing the lot of the coating liquid. If this cleaning is done manually by hand, the problem of contamination can be solved, but this takes too much time, and the operation stop time becomes long and the productivity deteriorates.

Further, if high-speed stirring is carried out to uniformly mix and dissolve the powder, foaming is likely to occur, and when the coating solution is applied to the support, bubble defects such as streaks occur. It also has the drawback of requiring time for defoaming.

The present invention has been made in view of the above circumstances, and has a simple device structure, and is liable to float on the liquid surface and hard to be entrained in the liquid even when stirred, and easily settles in the liquid. An object of the present invention is to provide a stirring tank in which powder can be uniformly mixed and dissolved in one tank and which can be easily washed.

[0008]

In order to achieve the above-mentioned object, the present invention provides an agitating shaft in a vertical tank with a flat plate inclined upper paddle and a lower paddle, and a vertical direction of the inner wall surface of the tank. An agitation tank in which a baffle plate is disposed in the upper part of the baffle plate is not located above the upper paddle position.

A conventional stirring tank having a combination of a stirring blade and a baffle plate prevents the stirring blade and the fluid from rotating,
The stirring effect is improved by generating the upstream and downstream in the tank. However, in the case where the powder to which the stirring tank of the present invention is applied is not stirred, when a powder that easily floats on the liquid surface and a powder that easily sediments on the bottom surface of the tank are mixed and dissolved, a baffle plate is used. Although it is effective for mixing and dissolving the powder that tends to settle in the upstream and downstream due to the baffle plate, it is difficult for the baffle plate to form a vortex around the stirring axis, so the powder that easily floats on the liquid surface is difficult to mix and dissolve in the dissolving liquid. Solubility becomes poor.
The present inventor has constructed a stirring tank suitable for mixing and dissolving a plurality of powders having different characteristics in a solution.

According to the present invention, since the upper end position of the baffle plate is not positioned above the upper paddle position, when the upper paddle is rotated, the upper and lower ends of the baffle plate are hardly generated in the upper part of the tank. A V-cut swirl flow around the stirring shaft, which winds the liquid into the liquid from the liquid surface, is strongly generated. As a result, even powder that easily floats on the liquid surface can be reliably caught in the liquid, so that it can be uniformly mixed and dissolved in the liquid. On the other hand, in the lower part of the tank, upstream and downstream are generated by the action of the lower paddle and the baffle plate, so even if the powder easily settles in the liquid, settling to the bottom of the tank is prevented and mixed and dissolved. You can Furthermore, since the stirring and mixing tank of the present invention has a simple device configuration, it is easy to wash and is unlikely to cause contamination.

In a preferred embodiment of the present invention, the baffle plate has an intersection angle of 95 to 14 between the baffle plate and the inner wall surface of the tank.
It is preferably formed in a triangular prism shape having an angle of 0 °. As a result, the flow of the liquid hitting the baffle changes its direction toward the center of the tank, so that the mixing and dissolution of the powder by the paddle can be promoted and the powder does not stay on the baffle.

In a preferred embodiment of the present invention, the position of the upper paddle is the liquid level height (height from the tank bottom to the liquid level).
It is preferable that the position of the lower paddle is 5 to 25% of the liquid surface height. This prevents bubbling on the liquid surface, and the upstream and downstream sides formed by the lower paddle and the baffle plate do not hinder the generation of a V-cut swirl flow formed by the upper paddle.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a stirring tank according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a conceptual diagram of a coating system 10 incorporating the stirring tank of the present invention. 2 is a vertical cross-sectional view of the stirring tank of the present invention, and FIG. 3 is a horizontal cross-sectional view.

The coating system 10 is mainly composed of a stirring tank 12 for stirring and dissolving various raw material powders in a liquid to prepare a coating solution, a stock tank 14 for stocking the prepared coating solution, and a defoaming device. 16 and the coating coater 18 are connected by a pipe 20.

As shown in FIGS. 2 and 3, the stirring tank 12 is mainly composed of a vertical cylindrical tank 60 provided with a stirrer 62 and a baffle plate 64. The stirrer 62 is
A stirring shaft 68, which is rotated by a motor 66, is arranged vertically in the center of the tank 60, and a flat plate inclined upper paddle 70 and a lower paddle 72 are attached to the stirring shaft 68. Paddle blade 7 of upper paddle 70 and lower paddle 72
The number of 4 is preferably about 2 to 4, but is not particularly limited. Further, the inclination angle of the paddle blades 74 is 45
The degree of about 0 is preferable. Upper paddle 70 and lower paddle 72
The stirring rotational speed of is preferably in the range of 50 to 150 rpm, because foaming occurs when the coating liquid is applied to the support 48 (see FIG. 1) when the speed is too high, and a range of 50 to 150 rpm is particularly preferable.
It is preferably in the range of 0 to 120 rpm. this is,
When the stirring rotation speed is less than 50 rpm, the flow of the liquid in the tank 60 is insufficient, and when it exceeds 150 rpm, foaming is likely to occur and a high shearing force is applied to the raw material, which may cause the raw material to aggregate. The position of the upper paddle 70 is 60 to 80% of the height of the liquid surface 76, and the lower paddle 7 is
The position of 2 is 5 to 25% of the height of the liquid surface 76. Although this has a balance with the stirring speed, the upper paddle 70
When 80% of the height of the liquid surface 76 is too close to the liquid surface, the upper paddle 70 is rotated to easily foam the liquid surface 76, and air near the liquid surface 76 is trapped in the liquid. On the other hand, when the upper paddle 70 is less than 60% of the height of the liquid surface 76, the depth of water to be arranged becomes too deep, so that a V-cut swirl flow is less likely to occur. Further, the lower paddle 72 has a liquid surface 76.
If it is less than 5% of the height, it will be too close to the lower part of the tank 60 to make it difficult for the upstream and downstream to occur due to the action with the baffle plate 64, while if it exceeds 25% of the height of the liquid level 76, the momentum of the upstream and downstream will be strong. Therefore, the V-shaped swirl flow generated by the upper paddle 70 is prevented.

On the inner wall surface 60A of the tank 60, four baffle plates 64 are vertically attached at 90 ° intervals. The number of baffle plates 64 is not limited to four and can be set arbitrarily. The baffle plate 64 and the upper paddle 70 are arranged such that the upper end 64A position of the baffle plate 64 is not located above the upper paddle 70 position. In this way, when the baffle plate 64 and the upper paddle 70 are arranged and the upper paddle 70 is rotated, a V-cut-like swirling flow that entrains the liquid in the liquid from the liquid surface 76 is generated in the upper portion of the tank 60. Incidentally, if the upper end 64A of the baffle plate 64 is located above the upper paddle 70 and is close to the liquid level 76, the tank 60
Since the upstream and downstream due to the baffle plate 64 occur in the inner upper part, a V-cut swirl flow is less likely to occur.

The shape of the baffle plate 64 is, as shown in FIG.
It is preferably formed in a triangular prism shape so that the intersecting angle (α) between the inner wall surface 60A of the tank 60 and the baffle plate 64 is 95 to 140 °. This is the intersection angle (α)
When the ratio is less than 95, the baffle plate 64 becomes close to a flat plate, so that the powder easily stays at the intersection 78 between the inner wall surface 60A and the baffle plate 64, and when it exceeds 140 °, the function as the baffle plate 64 is exerted. It becomes difficult to be played.

According to the stirring tank 12 constructed as described above, since the upper end 64A of the baffle plate 64 is arranged so as not to be located above the upper paddle 70 position, the rotation of the upper paddle 70 causes the inside of the tank 60 to rotate. A V-cut swirl flow that entrains the liquid in the liquid from the liquid surface 76 is generated in the upper part of the. As a result, even if the powder easily floats on the liquid surface 76 and is hard to be caught in the liquid even with stirring, the powder is caught in the liquid and mixed and dissolved. Further, since the powder that has moved into the liquid by riding the V-cut swirl flow reaches the upper paddle 70 and is crushed, it is possible to promote the mixing and dissolution even in the case of lumpy powder. The dissolution time can be shortened. On the other hand, in the lower part of the tank 60, the lower paddle 72 and the baffle plate 64 cause the upstream and the downstream, so that even the powder that easily settles in the liquid can be prevented from settling to the bottom of the tank 60.
In addition, the powder that has moved up and down is transferred to the lower paddle 72.
Since it reaches and is pulverized, it is possible to accelerate the mixing and dissolution even in the case of lumpy powder, and to shorten the mixing and dissolution time. Therefore, the agitation tank 12 of the present invention is suitable as an apparatus for agitating and dissolving the powder that easily floats on the liquid surface 76 and the powder that easily settles on the bottom surface of the tank 60 in the stationary solution without stirring.

The coating liquid prepared in the stirring tank 12 is stored in the stock tank 14 and is fed to the coating coater 18 by the liquid feeding pump 22 in accordance with the coating operation. As the liquid feed pump 22, a pressure-feed type non-pulsating pump, for example, a gear pump, can be preferably used so that foaming does not occur.

The defoaming device 16 mainly comprises the liquid feed pump 2
2, a pair of ultrasonic defoaming devices 24, 26 provided on both the upstream side and the downstream side, and a jacket 54 for adjusting the liquid temperature of the coating liquid to be defoamed.

The ultrasonic defoaming device 24 on the upstream side is a tank-type defoaming device in which an ultrasonic oscillator 30 is arranged at the bottom or the periphery of the ultrasonic tank 28, and the inside of the device 24 is open to the atmosphere. That is, or because the height difference from the stock tank 14 is small, a non-pressurized condition is formed. The ultrasonic defoaming device 24 on the upstream side irradiates ultrasonic waves under non-pressurized conditions to precipitate the bubbles in the coating liquid and grows / collects the deposited bubbles to float on the liquid surface. Foam. In this case, the frequency of the ultrasonic oscillator 30 is 20 KHz to 100 KHz.
Is preferable, and the internal pressure of the ultrasonic bath 28 is 0 to 20.
It is preferably within the range of kPa.

As shown in FIG. 4, the ultrasonic defoaming device 26 on the downstream side mainly includes a pipeline 34 arranged in the ultrasonic liquid tank 32 and a bottom portion or a peripheral portion of the ultrasonic liquid tank 32. The ultrasonic oscillator 36 is provided. The pipeline 34 is composed of a thin circular tube having a smooth inner surface, the inlet side is connected to the discharge side of the liquid feed pump 22 via a flow meter 38 (see FIG. 1), and the outlet side is a pressurizing valve 40. And, it is connected to the coating coater 18 via the bubble detector 43 (see FIG. 1). Then, the coating liquid flowing in the pipeline 34 is pressurized to a predetermined pressure level by the liquid feed pump 22 and the pressure valve 40. As the pressurization level, the internal pressure in the pipeline 34 is preferably 30 to 100 kPa. As a result, the coating liquid is pressure-fed in the pipeline 34 without a gas-liquid interface. Warm water, which is an ultrasonic wave propagating liquid, is continuously supplied into the ultrasonic liquid tank 32 from a water supply port 41 on the lower surface of the tank, fills the inside of the tank, and is discharged from a drain port 42 on the upper surface of the tank. This allows
The ultrasonic wave emitted from the ultrasonic oscillator 36 is propagated to the pipeline 34 by the ultrasonic wave propagating liquid,
The coating liquid flowing through the inside of 4 is irradiated. Further, the frequency with which the coating liquid flowing in the pipeline 34 is irradiated is 20
The range of KHz to 100KHz is good. As the bubble detector 43, for example, the bubble detector 43 described in JP-A-3-157103 can be preferably used. According to the bubble detector 43, the coating liquid flowing in the pipe 20 is irradiated with ultrasonic waves, and the change in acoustic impedance in the sound field caused thereby is converted into the electrical impedance of the ultrasonic transducer, and this change is detected as bubbles. The number of bubbles in the coating liquid is detected by outputting the electric signal from the container.

A jacket 54 for adjusting the temperature of the coating liquid is provided on the stock tank 14, the pipe 20, the pair of ultrasonic defoaming devices 24 and 26, and the coating coater 18,
The temperature of the coating liquid is adjusted within the range of 10 ° C to 50 ° C, which does not affect the quality of the coating liquid. The jacket 54 includes a first jacket 54A for adjusting the liquid temperature of the coating liquid so as to promote the deposition of bubbles in the device 24 from the stock tank 14 to the ultrasonic defoaming device 24 on the upstream side, and an upstream supersonic device 54A. A second jacket 54B that lowers the temperature of the coating liquid so as to promote the dissolution of bubbles in the ultrasonic defoaming device 26 from the downstream side to the ultrasonic defoaming device 26 on the downstream side; The third jacket 54C that further lowers the liquid temperature so that bubbles once dissolved in the ultrasonic defoaming device 26 downstream from the ultrasonic defoaming device 26 to the coating head 44 do not re-precipitate.
It consists of stages. In this case, the liquid temperature of the coating liquid in the coating coater 18 needs to be calculated backward on the basis that the set coating temperature is reached, and the liquid temperature needs to be lowered stepwise.

As the coating coater 18, an extrusion type coating coater 18 is provided. Coating coater 18
Is mainly composed of a coating head 44 and a backup roller 46 arranged in the vicinity of the tip of the coating head 44, and a traveling support 48 is supported by the backup roller 46. A pocket portion 50 into which the coating liquid is supplied in the coating head 44, and the coating head 4 from the pocket portion 50.
A slit 52 extending in the web width direction is formed up to the tip of No. 4. Then, after the coating liquid supplied to the pocket portion 50 is spread in the pocket portion 50, it rises in the slit 52 and is pushed out from the tip of the coating head 44. The extruded coating liquid forms a bead with the support 48,
The coating liquid is applied to the support 48 running through the beads. The coating coater 18 is not limited to the extrusion type coating coater, but may be a roll coater type, a gravure coater type, a slide bead coater type, or any other coating coater.

[0026]

EXAMPLES Next, examples using the stirring tank of the present invention will be described. A comparative example using a conventional stirring tank will be described together. (Embodiment 1) Powder A which is poured into the tank of the stirring tank of the present invention described with reference to FIGS. 2 and 3 and which easily floats on the water surface and is not easily entrained in water even if stirred Then, the powder B which easily forms a lump in water and easily precipitates was charged, and mixed and dissolved while heating. The formulations of the powder and the solution used, the mixing and dissolving conditions, and the stirring tank conditions are as follows. (Prescription of powder and dissolution liquid) -Powder A ... Polyvinylpyrrolidone (PVP) 50 kg-Powder B ... Polyvinyl alcohol (PVA) 50 kg-Dissolution liquid-Ion exchange water 900 kg (mixing dissolution conditions) -During powder charging Liquid temperature: 20 ° C-Liquid temperature during heating: 90 ° C-Heating time: 1 hour-Stirring speed: 100 rpm (stirring tank conditions) -Preparation volume: 1000 L-Paddle blade: 4-plate 45 ° tilt 2 Stage paddle / Paddle inner diameter ratio: 30% of tank inner diameter ・ Upper paddle position: 70% of liquid level height ・ Lower paddle position: 10% of liquid level ・ Baffle plate position: 20% of liquid level (obstacle) (Bottom edge of plate)
˜60% (upper end of baffle plate) ・ Intersection angle (α) of baffle plate ... 130 ° According to the first embodiment configured as described above, the upper part of the tank has a V-cut shape in which the liquid is wound from the liquid surface into the liquid. A strong swirl flow was formed, and upstream and downstream were formed in the lower part of the tank. As a result, the PVP powder was not retained on the liquid surface, but was caught in water by a strong V-cut swirl flow and mixed and dissolved. On the other hand, the PVA powder was mixed and dissolved on the upstream and downstream sides without settling in the lower part of the tank. Further, both the PVP powder and the PVA powder were not retained at the intersection of the baffle plate and the inner wall surface of the tank, but were guided to the center of the tank by the intersecting angle of the baffle plate and mixed and dissolved by the paddle. (Comparative Example 1) The baffle plate position was set at 20% (lower end of the baffle plate) to 80% (upper end of the baffle plate) of the liquid level, and the upper end position of the baffle plate was positioned above the upper paddle position. The other conditions are the same as in Example 1. As a result, a V-cut swirl flow, which entrains the liquid into the liquid from the liquid surface, was hardly generated in the upper part of the tank. As a result, most of the PVP powder stayed on the liquid surface and remained without being mixed and dissolved. Comparative Example 2 Only the upper paddle was used without setting the lower paddle. The other conditions are the same as in Example 1. As a result,
Upstream and downstream did not occur in the lower part of the tank. As a result,
Part of the PVA powder settled on the bottom surface of the tank and remained without being mixed and dissolved. (Comparative Example 3) Only the lower paddle was used without setting the upper paddle. The other conditions are the same as in Example 1. As a result,
No V-cut swirl flow, which entrains the liquid from the liquid surface into the upper part of the tank, was generated. As a result, most PV
The P powder stayed on the liquid surface and remained without being mixed and dissolved. (Comparative Example 4) The baffle plate was formed in a flat plate shape, and the angle of intersection with the inner wall surface of the tank was 90 °. The other conditions are the same as in Example 1. As a result, a part of the PVA powder stayed at the lower portion of the tank and at the intersection of the inner wall surface of the tank and the baffle and remained without being mixed and dissolved. (Comparative Example 5) The intersection angle between the baffle plate and the inner wall surface of the tank was set to 16
It was set to 0 °. The other conditions are the same as in Example 1. As a result, upstream and downstream did not occur well in the lower part of the tank.
As a result, a part of the PVA powder settled in the lower part of the tank and remained without being mixed and dissolved.

[0027]

As described above, according to the stirring tank of the present invention, it is possible to settle in powder or liquid which is easy to float on the liquid surface and is hard to be caught in the liquid even if it is stirred with a simple device configuration. Easy powder can be mixed uniformly in one tank.
Furthermore, since the device configuration is simple, cleaning is easy and contamination is unlikely to occur.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a coating system incorporating a stirring tank of the present invention.

FIG. 2 is a vertical sectional view of a stirring tank of the present invention.

FIG. 3 is a cross-sectional view of the stirring tank of the present invention.

FIG. 4 is an explanatory diagram illustrating a configuration of a downstream ultrasonic defoaming device.

[Explanation of symbols]

10 ... Coating system, 12 ... Agitation tank, 14 ... Stock tank, 16 ... Defoaming device, 18 ... Coating coater, 20 ...
Piping, 22 ... Liquid feed pump, 24 ... Ultrasonic defoaming device on upstream side, 26 ... Ultrasonic defoaming device on downstream side, 28 ... Ultrasonic tank,
30 ... Ultrasonic oscillator, 32 ... Ultrasonic liquid tank, 34 ... Pipeline, 36 ... Ultrasonic oscillator, 38 ... Flowmeter, 40 ... Pressurizing valve, 43 ... Bubble detector, 44 ... Coating head, 46
... backup roller, 48 ... support, 50 ... pocket part, 52 ... slit, 54 ... jacket, 60 ... tank, 62 ... stirrer, 64 ... baffle plate, 66 ... motor, 68
... stirring shaft, 70 ... upper paddle, 72 ... lower paddle, 74
… Paddle blades, 76… Liquid level, 78… Intersection

Continued front page    F-term (reference) 4F042 AA22 CA01 CA06 CA07 CB02                       CB19 ED05                 4G035 AA23 AB46                 4G078 AA01 AB01 AB05 BA05 BA09                       CA01 CA08 CA12 CA17 DA01

Claims (4)

[Claims] 1. A stirring tank in which a vertical shaft-type upper paddle and a lower paddle are provided on a stirring shaft in a vertical tank, and a baffle plate is arranged in the vertical direction of the inner wall surface of the tank. An agitation tank, wherein the upper end position of the baffle plate is not located above the upper paddle position. 2. The solution is poured into the tank, and powder that easily floats on the liquid surface and powder that easily settles on the bottom of the tank are charged, and the powder is mixed and dissolved in the solution. The stirring tank according to claim 1, characterized in that. 3. The stirring tank according to claim 1, wherein the baffle plate is formed in a triangular prism shape having an intersection angle of 95 to 140 ° between the baffle plate and the inner wall surface of the tank. . 4. The position of the upper paddle is at a liquid level height of 60.
-80%, the lower paddle position is 5-2 of the liquid level
5%, The stirring tank as described in any one of Claims 1-3.