JPS6238209A - Degasifying treatment process of high viscosity fluid under reduced pressure - Google Patents

Abstract

PURPOSE:To remove efficiently under low temperature the gas mixed and solved in the high viscosity fluid by moving gradually the fluid from the first vessel to the second vessel under reduced pressure. CONSTITUTION:With the cock 6 closed, an adequate quantity of high viscosity fluid to be degasified is put into the first vessel 1, and after the opening being completely closed with the rubber stopper 4 and also the cock 6a and 8 being closed to drive the air exhauster 10, the connecting device is depressurized by opening the cock 8. Next, the first vessel 1a and the second vessel 2a are moved and rotated on the same level supported by the center of clamp 3 connecting the branching tubes 1a and 2a. The slurry in the first vessel 1 flows through the connected branching tube 1a and 2a and fills up gradually the second vessel 2. As the slurry flow-line is depressurized down to around 5- 10cmHg, degasification is carried out efficiently while the slurry flows through the line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a method for degassing a highly viscous fluid in which gas is mixed or dissolved under reduced pressure.

[Prior art and its problems]

For example, when manufacturing ceramic plates, etc., a highly viscous slurry consisting of raw material powder, an organic binder, a plasticizer, a deflocculant, and a solvent is usually used, such as by the doctor blade method.
After forming the slurry into a green sheet, it is fired at a high temperature or during the process of manufacturing this slurry, gases such as air are likely to be mixed in or dissolved, and once mixed or dissolved, the slurry will not last for a short time because the slurry has a high viscosity. There has been a long-standing problem that it is difficult for internal substances to be released to the outside.

If a green sheet is formed with gas present in the slurry, the flatness of the green sheet will be damaged by air bubbles appearing on the surface, so deaeration treatment is performed to actively remove the gas present inside the green sheet during the forming process of the green sheet. must be carried out.

Several methods have been known for degassing this type of highly viscous fluid, but a relatively simple method is:
There are methods of degassing the fluid by adding defoaming or an antifoaming agent to the fluid, or heating the fluid to lower its viscosity, and there is also a vacuum degassing method.

The method of adding defoamers and antifoaming agents can be very effective depending on the type of raw material powder, organic binder, solvent, etc. in the fluid, but on the other hand, it is rarely effective ( Therefore, it is difficult to find an optimal defoaming agent or antifoaming agent that can be used in general, regardless of the fluid constituent material.

Furthermore, depending on the chemical composition of the defoamer or antifoaming agent used, it may cause a chemical reaction with the components of the fluid, which may adversely affect the performance of the final product.

The deaeration method, which raises the temperature of the fluid and lowers its viscosity while at the same time making use of the thermal expansion of the gas mixed in the fluid to cause air bubbles to rise naturally, is the simplest and easiest method, and is highly recommended because it prevents solvent evaporation. The temperature cannot be raised too high, and there is a limit to the deaeration ability.

The vacuum degassing method is the most common, but as mentioned above, for fluids containing organic solvents, increasing the temperature will increase the evaporation of the solvent, so even if the pressure is extremely low, the same result will not occur. As a result, long-term decompression degassing must be carried out at a low temperature and under an appropriate reduced pressure. However, if a fluid with powder dispersed in it is depressurized for a long time in a stationary state, the powder will settle at the bottom of the fluid, creating a density difference with the top, and the solvent will partially evaporate at the surface of the fluid. This has the drawback that degassing is inhibited, such as the formation of an agglomerated film on the surface. On the other hand, it is possible to use a stirrer to forcibly stir the fluid while degassing it, but doing so may cause gas to be mixed in, and there are issues with sealing between the stirrer and the vacuum container. There are some problems such as.

[Purpose of the invention]

The present invention has been made in view of the above points.

The purpose is to remove gas mixed or dissolved in a highly viscous fluid, such as a slurry made by dispersing powder and binder in an organic solvent, using a simple device without using defoamers or stirring. It is an object of the present invention to provide a reduced pressure degassing method that can efficiently remove gas at low temperatures and in a short time.

[Key points of the invention]

Using a device in which two tubular containers with one end closed are arranged perpendicularly to each other on the longitudinal extension line and connected with pipes branching from the sides of each container with appropriate spacing, the first container is connected. After filling the first container with a high viscosity fluid containing gas in a vertically standing state, the first container is depressurized by an exhaust device and the first container is moved around the container connection part. The second container rotates so as to move on the same plane, and the fluid is gradually transferred from the first container to the second container, so that when the fluid flows through the connecting pipe, it forms a continuous ribbon. At this time, the gas contained in the fluid is easily released, and the second container finally rotates until it reaches the vertical position, completing the transfer of fluid between the containers and simultaneously starting the degassing process. It was also completed.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a sectional view of a main part of the apparatus used in the present invention. 1st
In the figure, a branch pipe 1a with a diameter of about 30 m is arranged upwardly in the longitudinal direction of the first container 1 at the top of a first container 1 made of a glass tube with a diameter of about 60 m, for example, with one end closed.
The second container 2, which is attached at an angle of 5 degrees and has exactly the same shape as the first container 1, is also provided with a branch pipe 2a. These two containers 1 and 2 are joined together in this way by bringing the end faces of the respective branch pipes 1a and 23 into close contact by rubbing together, and fixing the connecting parts of both limb pipes from the outer periphery airtight with the clamps 3. The first
The container 1 and the second container 2 communicate with each other through branch pipes 1a and 2a, and their positional relationship is on the same plane, so that the first container 1 and the second container 2 are longitudinally parallel to each other. It is configured to be orthogonal on the extension of the direction. Furthermore, the openings of the first container l and the second container 2 are both connected to rubber stoppers 4.
It is tightly closed with ゜4a, and the bottom is connected to the discharge pipes 5 and 5a.

6a is attached, especially one of the containers,
In the case of FIG. 1, an exhaust pipe 7 and a cock 8 are provided in the rubber stopper 4 of the first container 1, and one end of the exhaust pipe 7 is connected to an exhaust device 10 through a rubber pipe 9.

In the present invention, using a device in which two containers are connected as described above, first, the container is closed, an appropriate amount of high viscosity fluid to be degassed is poured into the first container, and the opening is sealed with a rubber stopper 4. After closing the condensers a and 8 and driving the exhaust device 10, the cock 8 is opened and the connected containers are brought into a reduced pressure state. Next, the first container 1 and the second container 2 are rotated using the center of the clamp 3 connecting the branch pipes 1a and 23 as a fulcrum so that they move on the same plane. However, the rotation drive mechanism and the container support mechanism are omitted in FIG.

The movement of the positions due to the rotation of the two containers is conceptually shown in FIG. 2 as a degassing process. However, although FIG. 2 only shows the connecting container and other components are omitted, the deaeration effect of the present invention will be explained with reference to FIG. 2.

First of all, as shown in Figure 2(a), for example, the viscosity is 5 at room temperature.
A first container 1 containing an appropriate amount of ceramic slurry 11 for sheet forming of 000 to io 2a, it is located diagonally above, and its longitudinal direction is parallel to the floor surface. From this state, the first container 1 and the second container 2 move on the same plane using the center of the clamp 3 as a fulcrum, so that the first container 1 is located above and the second container 2 is located below. Rotate gradually. Figure 2(b)
shows the state in which the connecting container is in the middle of rotation. This rotation causes the slurry IJ-11 in the first container l to
flows through the connected branch pipes 1a and 23, and gradually flows into the second branch pipe 1a and 23.
It will accumulate in container 2. The rotation of the connected container further progresses, and when the second container 2 becomes perpendicular to the floor surface, that is, as shown in FIG. 2(C), the rotation is stopped.
Contrary to the positional relationship between the containers at the start in FIG. 2(a), the first container 1 is diagonally above the second container 2, and its longitudinal direction is parallel to the floor surface. As a result, the slurry 11 is completely transferred from the first container 1 to the second container 2.

Through the process of Figure 2 (a) to (C), the two containers 1 and 2
The slurry flow path connecting the branch pipes 1a and 2a is 5~10c even during these rotations! Since the pressure is reduced to about ILHg, the gas present in the slurry IJ-11 is degassed, but in the present invention, the flow formed by the branch pipes 1a and 2a of the first container 1 and the second container 2 is Slurry gradually flows down the road (
In other words, the slurry 11 staying in the first container 1 will not change the surface from which air bubbles can escape, but if the slurry 11 passes through the branch pipes 1a and 2a, the air will be effectively degassed. Since the flow is continuous in a thin strip along the path and the surface is constantly renewed, minute air bubbles existing at the bottom are always guided to the vicinity of the surface and deaeration is easily performed. Therefore, the path through which the slurry 11 flows needs to be a certain distance;
It is best to set the rotation speed to about 00 m, and it is necessary to make the rotation speed considerably slow so that the slurry 11 can be transferred between containers as a thin strip. It is best to determine the optimal conditions. The slurry 11 thus deaerated is discharged into the discharge pipe 5a shown in FIG.
The container can be opened and taken out, and the next time the degassing process will be done, the two containers will remain in the same position.

Put Slur IJ-11 into the second container 2, and do the same as above for 90. . This can be done by rotating the slurry 11 towards the first container 1.

As described above, when degassing a fluid containing gas, the present invention can be processed in a short time because the fluid only needs to be transferred between depressurized containers through a connecting pipe without heating or stirring. , it can be carried out even with a small amount of processing, and the point at which the processing ends is extremely clear. Further, when the fluid has thixotropic properties like a slurry, the viscosity decreases when flowing between containers, so there is an advantage that the degassing effect becomes even more pronounced.

〔Effect of the invention〕

When degassing gas mixed or dissolved in a high viscosity fluid under reduced pressure, conventional depressurization alone is inefficient, so heating,
Although auxiliary means such as stirring were used, the evaporation of the solvent was significant and stirring was not easy in highly viscous fluids, which actually impaired the degassing effect due to the lack of consistency. According to the above, as explained in the example, two containers connected by a branch pipe are brought into a reduced pressure state, and the containers are slowly rotated using the connection as a fulcrum, and the fluid contained in one container is transferred through the connection pipe to the other. Since the surface area of the fluid is substantially expanded by transferring it to an empty container, degassing of the fluid can be carried out reliably by simply rotating the container, thereby eliminating the negative effects of evaporation of solvents, etc. In addition, it is possible to carry out vacuum degassing treatment efficiently in a short period of time without using any auxiliary means.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an apparatus to which the method of the present invention is applied;
FIG. 2 is a conceptual diagram showing the degassing process according to the present invention. l...first container, la, 2a...branch pipe, 2...
・Second container, 3... Clamp, 4.4a... Rubber stopper, 5゜5a, 7... Discharge pipe, G, 6a, 8... Cock, 10 Fig. 1

Claims (1)

[Claims] 1) Close one end and make a 45° angle with the opening surface on the side near the opening on the other end.
Two tubular containers each having a branch pipe having an inclination of Stand vertically, and after injecting the fluid to be treated, seal the openings of both tubular containers, and while exhausting air from either tubular container, place both tubular containers on the same plane perpendicular to the floor using the branch pipe connection as a fulcrum. A method for vacuum degassing treatment of a high viscosity fluid, characterized in that the fluid to be treated is transferred from a first tubular container to a second tubular container through a connecting pipe by rotating the fluid by 90°.