JP2917264B2 - Defoaming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defoaming device for defoaming bubbles in a viscous liquid such as paint.

[0002]

2. Description of the Related Art For example, in a paint, air bubbles contained in the paint may cause a defect in a coating film or may hinder the work. For example, it is common to apply paint while circulating paint between the paint tank and the coating equipment. At this time, the return pipe is located at the top of the paint tank, and the paint is dropped from above into the paint tank. Is common. However, in this method, air is trapped when falling from the return pipe, and a large amount of air bubbles mix into the paint in the paint tank. In addition, air was trapped by air pockets in the pipes or by a pressure pump, and air was trapped when the paint was supplied into the paint tank, so that the paint in the paint tank was often full of bubbles.

[0003] When the paint in the paint tank is full of bubbles, the foam overflows from the paint tank or the paint is not smoothly discharged from the coating device, which hinders the painting operation and causes a problem in production. There is a problem that the performance is reduced. Therefore, conventionally, a defoaming function has been provided from the viewpoint of paint composition, such as addition of an antifoaming agent. However, there are obstacles due to the defoamer itself and various restrictions on the formulation, and it is necessary to consider not only the hard side of the paint but also the defoaming from the soft side that defoams during use.

[0004] For example, Japanese Patent Application Laid-Open No. 51-101263 discloses that air is blown near the liquid surface of a liquid so that the liquid near the liquid surface collides with a collision plate, thereby breaking bubbles existing near the liquid surface. An antifoaming device is disclosed. Further, Japanese Patent Application Laid-Open No. 5-115706 discloses a defoaming device that breaks bubbles near the liquid surface by stroking the liquid surface near the surface with a rotating defoaming arm.

[0005]

The defoaming devices disclosed in the above two publications break bubbles near the liquid surface. However, bubbles also exist in the liquid,
It does not always exist concentratedly near the liquid surface. In addition, in the case of a liquid having a high viscosity or a large thixotropic property, the speed at which bubbles contained in the liquid rise to the liquid surface is slow, and it takes a long time to defoam bubbles contained in the liquid in the above device. There's a problem. Further, particularly in a liquid having a large thixotropy, there is a problem that it is difficult for bubbles to move to the surface and remains in the liquid.

The present invention has been made in view of such circumstances, and an object of the present invention is to enable bubbles contained in a liquid to be smoothly broken.

[0007]

A defoaming device according to the present invention for solving the above-mentioned problems is a device for defoaming bubbles contained in a liquid, comprising: a sub-tank for temporarily storing a liquid to be defoamed; It consists of supply means for supplying liquid to the sub tank,
The sub-tank opens upward, and the liquid
Over the upper surface of the weir that forms at least a part of the surrounding wall
And then flow out as a film along the outer surface of the sub tank.
The weir section has a thin plate shape in the liquid outflow direction.
None, the upper end surface of the weir is configured horizontally in the longitudinal direction,
Bubbles in the liquid in the tank are generated when the liquid passes over the weir
It is characterized by being configured to break bubbles .

[0008]

In the defoaming device of the present invention, the liquid is first supplied to the sub-tank by the supply means, and is temporarily stored in the sub-tank. Then, the liquid level gradually rises due to the continuation of the supply, and when the liquid level exceeds the height of the weir, the liquid in the sub-tank passes over the weir and flows out in a film form along the outer surface of the sub-tank.

Here, the upper end surface of the weir portion is formed horizontally in the longitudinal direction. Therefore, when the liquid gets over the weir, the liquid becomes a film having a uniform thickness in the longitudinal direction, and the film thickness can be reduced as the supply amount of the supply means is reduced. As a result, even bubbles contained in the liquid are forcibly positioned on the surface. Then, a tensile stress acts on the gas bubbles having a diameter larger than the film thickness when going over the weir. As a result, it is assumed that a stress exceeding the surface tension is generated in the bubbles and the bubbles break.

[0010] Then, the liquid in which the bubbles are broken and the bubbles disappear when passing over the weir portion is formed into a film as it is and flows out along the outer surface of the sub-tank, so that entrapment of new bubbles is prevented. Furthermore, if a plurality of the sub-tanks are used, it is possible to break bubbles that have escaped without breaking in one sub-tank in the next sub-tank, and the defoaming efficiency is further improved.

[0011]

The present invention will be specifically described below with reference to examples. (Embodiment 1) FIG. 1 is a perspective view of a main part of a defoaming apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram of a coating system using the defoaming apparatus.

This defoaming device is for defoaming bubbles contained in the paint, and comprises a sub-tank 1 and a pump 2 for supplying the paint to the sub-tank 1. Sub tank 1
Is adjacent to the main tank 3. The pump 2 pumps up the paint 40 from the drum 4 and supplies it to the sub tank 1, and the paint 40 flowing from the sub tank 1 to the main tank 3.
Is pumped to the spray gun 6 via the second pump 5,
The paint is applied by the spray gun 6. Also, when not painting,
The paint returns from the spray gun 6 to the sub-tank 1 to form a circulation circuit.

The sub-tank 1 is 400 mm × 400 mm
Is a rectangular parallelepiped container having an opening at the top and a depth of 250 mm. The main tank has a diameter of 1200 mm and a depth of 8
It is a 00 mm cylindrical container. The sub-tank 1 and the main tank 3 are adjacent to each other via a weir portion 10, and their upper end surfaces are located on the same plane. And the weir 10
The upper ends of the sub-tank 1 and the main tank 3 are lower than the upper ends by 30 mm, and the upper ends are horizontal in the longitudinal direction.
The outer surface of the weir portion 10 on the main tank 3 side is smoothly continued to the inner peripheral surface of the main tank 3. Further, a pipe from the pump 2 is connected to the bottom surface of the sub tank 1.

In the defoaming apparatus according to the present embodiment, the paint 40 pumped from the drum 4 by the pump 2 is gradually stored in the sub tank 1 from the bottom surface of the sub tank 1. This prevents new air from being entrained during supply from the drum 4. And the height of the paint 40 stored in the sub tank 1 is
When the height exceeds zero, the paint 40 flows over the weir portion 10 and flows into the main tank 3.

When the paint 40 gets over the weir section 10,
As shown in FIG. 3, a thin film is formed. Then paint 4
The bubbles 41 contained in the bubble 41 are deformed so as to be stretched at the position of the upper end surface of the weir portion 10, and the bubbles 41 are deformed by the stress.
Breaks bubbles. Here, the upper end surface of the weir portion 10 is horizontal in the longitudinal direction. Therefore, the film thickness of the paint that passes over the weir portion 10 is uniform throughout the longitudinal direction of the weir portion 10, and the foam breaking efficiency is also uniform. The defoamed paint 40 is applied to the dam 10
Gently flows into the main tank 3 along the outer surface of
Entrapment of new air is prevented.

The bubbles are extended along the upper end surface of the weir section 10, and it is preferable that the amount of extension be large. Therefore, as shown in FIG.
It is desirable that the shape of the upper end surface be a curved shape such as an arc-shaped cross section. By doing so, the area of the upper end surface of the weir portion 10 is increased, and the foam breaking efficiency is further improved. The outer surface of the weir 10 connected to the main tank 3 may be formed as a vertical plane as in the embodiment, but if the inflow is large, turbulence may occur and air may be trapped. Therefore, FIG.
It is also preferable that the main tank 3 is configured to be continuous with an inclined surface as shown in FIG. (Embodiment 2) FIG. 6 is a sectional view of a defoaming apparatus according to a second embodiment of the present invention. In this embodiment, three sub-tanks 11 to
13 in order, and paint 4 stored in sub-tank 11
0 is stored in the sub tank 12 over the weir portion 14,
Further, it is configured to pass over the weir portion 15 of the sub-tank 12 and stored in the sub-tank 13, and further pass over the weir portion 16 of the sub-tank 13 and be stored in the main tank 3.

According to the defoaming apparatus of the present embodiment, even bubbles that do not break when passing over the weir section 14 are expected to break when passing over the weir section 15 or 16. The defoaming efficiency is further improved. (Embodiment 3) The defoaming apparatus of this embodiment is shown in a perspective view of a partial section in FIG. This defoaming apparatus has the same configuration as that of the first embodiment except that the sub tank 1 is formed on the entire periphery of the main tank 3.

That is, in the present embodiment, the periphery of the opening of the main tank 3 constitutes a ring-shaped weir portion 10. As a result, the length of the weir portion 10 becomes extremely long. Therefore, even when the supply amount of the paint to the sub-tank 1 is reduced to increase the foam breaking efficiency, the supply amount of the paint to the main tank 3 is increased. As a result, productivity can be improved.

[0019]

According to the defoaming device of the present invention, when the liquid passes over the weir, it forms a film, and the bubbles contained in the liquid in the film break. Even bubbles contained in the liquid can be efficiently defoamed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a use state of an antifoaming device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a coating system using the defoaming device of one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a main part of a weir portion of the defoaming apparatus according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view of a main part of a weir section, showing another mode of the defoaming device of the embodiment.

FIG. 5 is a cross-sectional view of a main part of a weir, showing another mode of the defoaming device of the embodiment.

FIG. 6 is a sectional view of a defoaming device according to a second embodiment.

FIG. 7 is a perspective view showing a partial cross section of a defoaming apparatus of a third embodiment.

[Explanation of symbols]

1: Sub tank 2: Pump (supply means) 3:
Main tank 10: Weir 40: Paint

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B01D 19/02 B01D 19/00

Claims (1)

(57) [Claims] An apparatus for defoaming bubbles contained in a liquid, comprising: a sub-tank for temporarily storing a liquid to be defoamed; and a supply means for supplying the liquid to the sub-tank. The liquid opens upward and the liquid
Above the weir that forms at least part of the peripheral wall of the sub tank
After passing over the surface, form a film along the outer surface of the sub tank
The weir portion is formed in a thin plate shape in the outflow direction of the liquid.
The upper end surface of the weir is formed horizontally in the longitudinal direction,
Bubbles in the liquid in the cavity are formed when the liquid passes over the weir
A defoaming device characterized by being configured to break into bubbles.