JP3352969B2 - Method for detecting organic foreign matter in ceramic raw material powder, ceramic slurry or ceramic granulated powder and method for removing organic foreign matter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for detecting and removing organic foreign substances in a raw material, for example, in the production of a beta-alumina solid electrolyte, and more particularly, to a method in a ceramic raw material, a ceramic slurry, or a ceramic granule. The present invention relates to a method for detecting a small amount of organic foreign matter present therein and a method for removing the same.

[0002]

2. Description of the Related Art In general, functional ceramics are manufactured using highly refined and high-purity ceramic raw materials as starting materials, and through slurry adjustment, granulation, molding, and firing processes. Defective products that do not satisfy the above may occur.

For example, in the production of a beta-alumina solid electrolyte used for a sodium-sulfur battery, although it is a small ratio of about one in 100,000, it is usually useful for a sodium-sulfur battery having 2500 or more charge / discharge cycles or more. A defective battery having a life of about 500 charge / discharge cycles has been generated.

[0004] A sodium-sulfur battery is used in a module battery in which a number of cells are connected in series and in parallel. When a large number of cells are used in the module battery, even if the frequency is low, defective cells are used. It is not preferable that a battery is generated.

[0005]

Accordingly, the present inventors have conducted a thorough analysis and investigation on defects present locally in the beta-alumina solid electrolyte of a defective unit cell. as a result,
Light transmission test on beta alumina solid electrolyte of defective unit cell,
Ultra-small pinholes that cannot be easily detected by penetrant testing (burnout holes of fibrous foreign matter; for example, diameters of about 10 to 30)
μm, about 1000-2000 μm in length).

It is presumed that one of the causes of the generation of these pinholes in the solid electrolyte is due to the use of a raw material powder mixed with a small amount of organic foreign matter for some reason in the process of manufacturing the raw material powder.

Another factor is the process of adjusting the slurry or the process of producing granulated powder. In cleaning the pipeline or the like at regular intervals during the production process or at the time of repair, the clothes and gloves of the worker may be damaged. Fiber or body hair, etc., in trace amounts, remained in the pipeline, etc., or due to defects such as urethane rubber used in the lining of the pipeline, etc., that organic foreign matter was mixed in the slurry or granulated powder. It is presumed to be due to.

Therefore, in order to provide a solid electrolyte with an extremely low failure rate, in a manufacturing process, a sampling inspection is performed to determine whether a solid electrolyte is used in a ceramic raw material powder, a slurry,
Alternatively, it is necessary to detect the presence or absence and the amount of the organic foreign matter mixed in the granulated powder, and to remove the organic foreign matter if it is mixed.

Accordingly, the present inventors have tried to detect and remove these organic foreign substances by a conventionally known elutriation technique. However, although there are organic fibers floating in the water, organic foreign substances (for example, polyester single fibers or urethane rubber fragments having a relatively large specific gravity) remain in the settled ceramic granulated powder, and the ceramic granulated powder is It is difficult to reliably separate the organic foreign matter from the organic matter.

[0010]

Means for Solving the Problems The present inventors have conducted various studies in order to solve the above-mentioned problems, and as a result, have completed a method for efficiently and reliably detecting organic foreign matter and a method for removing organic foreign matter.

That is, according to the present invention, there is provided a method for detecting an organic foreign substance present in a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder, wherein the hydrophobic organic solvent layer has a specific gravity smaller than that of water. Water layer 2
The hydrophobic organic solvent layer of the layer solution is mixed in a suspended state by a stirrer to form a suspension layer, and then a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder is charged, and the suspension is stirred by the stirrer. After continuing the turbid mixing for a predetermined time, the ceramic raw material powder is characterized in that the suspension layer and the water layer are separated, and an organic foreign substance mixed in the suspension layer is detected. A method is provided for detecting the presence or absence and the amount of organic foreign matter in ceramic slurry or ceramic granulated powder.

[0012] In the detection method of the present invention, the hydrophobic organic solvent is preferably 1-octanol. In addition, in the detection method of the present invention, it is preferable that the stirring rotation speed by the stirrer is continuously or stepwise reduced after the charging of the ceramic raw material powder, the ceramic slurry, or the ceramic granulated powder is completed.

[0013] Further, in the detection method of the present invention, the stirrer for mixing and stirring the hydrophobic organic solvent and water in a suspended state is a stirrer having a structure in which stirring disks are attached to a disk. It is preferable that a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder is charged on the upper surface and dispersed in the suspension layer.

According to the present invention, the hydrophobic organic solvent layer of a two-layer solution composed of a layer of a hydrophobic organic solvent having a lower specific gravity than water and a layer of water is mixed in a suspended state with a stirrer. To form a suspension layer, and then feed ceramic raw material powder, ceramic slurry, or ceramic granulated powder,
A ceramic raw material powder characterized by separating organic contaminants in a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder into the suspension layer by mixing in a suspension state by the stirrer for a predetermined time. The present invention provides a method for removing organic contaminants in medium, ceramic slurry, or ceramic granulated powder.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In the detection method and the removal method of the present invention, as shown in FIG. 2, a two-layer solution comprising water 2 in a water tank 1 and a hydrophobic organic solvent 3 having a specific gravity smaller than water is prepared. As shown in FIG. 1, a hydrophobic organic solvent is mixed in a suspended state by a rotating blade section 5 of a stirrer 4 to form a suspension layer 6.

A ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder (hereinafter referred to as “ceramic granulated powder or the like”) stored in a container 8 is placed on a suspension layer 6 in which a number of droplets 7 of a hydrophobic organic solvent are present. Is directly input in the case of slurry, and is input by the vibration feeder 10 in the case of powder or granulated powder.

By continuing the mixing by the stirrer 4 for a predetermined time, the organic foreign matter 11 mixed in the ceramic granulated powder 9 or the like comes into contact with the hydrophobic organic solvent droplet 7 in the suspension layer 6. As shown in FIGS. 3 (a) and 3 (b), a droplet 7 of a hydrophobic organic solvent having an affinity for the organic foreign substance 11 covers the whole or a part of the organic foreign substance 11, and is separated from the organic foreign substance. The granulated powder (or ceramic particles) 12 settles on the water floor. On the other hand, organic foreign substances are particles 7 of hydrophobic organic solvent.
And floats in the suspension layer 6 without settling.

Here, the thickness (depth) of the layer of water 2 is equal to or greater than the thickness (depth) of the suspension layer 6.
It is preferable because granulated powder (or ceramic particles) separated from organic foreign matter can be surely separated from the suspension layer. In addition, the thickness of the water layer refers to the distance between the upper surface of the sedimentation of the granulated powder (or ceramic particles) 12 settled on the bottom of the water tank 1 and the interface between the suspension layer 6 and the water 2.

In addition, by reducing the stirring speed continuously or stepwise, the thickness of the suspension layer 6 gradually decreases,
The granulated powder (or ceramic particles) floating in the suspension layer 6 is easily transferred to the water 2 side. As a result, the separation of the granulated powder (or ceramic particles) 12 from the organic foreign matter is promoted, and it is ensured. This is preferred because it is performed.

After the stirring is stopped, the suspension layer 6 is suctioned with a pipette or the like, filtered, and organic foreign matter remaining on the filter is observed and measured with a microscope to detect the presence or absence of the organic foreign matter and the amount of the organic foreign matter. Can be detected. After the suspension, the suspension was allowed to stand, and the suspension layer 6 was separated into two layers, water and a hydrophobic organic solvent. This is preferable because almost no ceramic particles are mixed.

The filter body is a metal mesh, and in that a tatami-mat filter ensures that organic fibers such as single fibers remain on the filter body, and it is easy to discriminate between the metal mesh and organic foreign matter. It is preferable in that it becomes. The opening of the mesh is preferably, for example, about 5 to 10 μm, and may be appropriately selected depending on the size of the organic foreign matter to be removed.

The hydrophobic organic solvent preferably has an affinity for organic foreign substances, and is preferably octanol, particularly 1-octanol, which has an affinity for organic foreign substances mainly composed of fibrous foreign substances. In the case where an organic lining material is used in a ceramic production line, and there is a problem of mixing of organic foreign substances due to a defect in the lining material, a hydrophobic organic solvent having a strong affinity for the organic lining material may be used. preferable.

When the granulated powder 9 or the like 9 is charged into the suspension layer 6,
It is preferable to add the granulated powder 9 and the like so as to be dispersed in the suspension layer 6 as much as possible, since the chance of the organic foreign substance coming into contact with the droplet 7 of the hydrophobic organic solvent increases.

Therefore, as shown in FIG.
The wings 14 are radially attached to the periphery of the disk 13,
It is preferable that the stirrer 4 is provided with a rotary blade 5 having a structure projecting below the lower surface 13a of the disk and projecting above the upper surface 13b of the disk.

In the stirrer having such a structure, when the suspension layer 6 is stirred, the suspension layer 6 is stirred by the wings 14 a protruding downward from the lower surface 13 a of the disk, and the disk exposed to the air is stirred. This is because the granulated powder 9 or the like put into the upper surface portion 13b can be dispersed in the horizontal direction by the wing portions 14b protruding from the upper surface portion 13b of the disk.

As shown in FIG. 5, the wings 14 have a structure protruding only below the lower surface 13 a of the disk, and the granulated powder or the like put on the upper surface 13 b of the disk exposed to the air A stirrer provided with a rotating blade 5 having a structure in which the disk upper surface 13b on which the rotating member 9 rotates is dispersed in the horizontal direction is also preferable.

Further, as shown in FIG. 6, a rotary blade 5 having a notch 13 c radially provided on the periphery of the disk 13.
A stirrer equipped with is also preferred. The stirrer of such a structure is
It is preferable that the granulated powder 9 or the like 9 put on the upper surface portion 13b of the disk is dispersed in the direction of the peripheral edge of the disk and is also injected into the suspension layer 6 from the notch portion 13c and widely dispersed.

When the granulated powder or the like is introduced without stirring the hydrophobic organic solvent 3 (that is, in the state of FIG. 2), each granulated powder (or The ceramic particles are likely to be in a “dama” (dump-like) state in the layer of the hydrophobic organic solvent 3, and the separation from the organic foreign matter cannot be performed reliably.

[0029]

[Example] 20 liters of water and 500 c in a transparent container
1-octanol of c was added, and the 1-octanol layer was mixed in a suspended state at a rotation speed of 600 rpm by a stirrer equipped with a rotary blade 5 shown in FIG. 6 to form a suspension layer.
The thickness of the suspension layer was about 100 mm.

Diameter 8-10 μm, length 0.5-2.0 m
Then, 10 kg of beta-alumina granulated powder mixed with 10 organic monofilaments having a length of 10 m was sequentially charged into the upper surface of the disk of the stirrer using a vibration feeder. Stirring was continued for 20 minutes after the addition was completed. Next, the stirring rotation speed was reduced to 75 rpm, and the mixture was stirred for 5 minutes.

Thereafter, the stirring is stopped, the suspension layer is suctioned with a pipette, and a tatami-mat metal mesh having an opening of about 10 μm is filtered as a filter, and the organic single fiber remaining on the filter is removed with a microscope. Observed. As a result, all the added organic single fibers were observed. That is, the organic foreign matter mixed in the granulated powder could be reliably detected.

In the production of the beta-alumina solid electrolyte, for the ceramic raw material powder such as α-alumina raw material powder, the slurry-adjusted ceramic slurry, and the granulated powder after the granulation step, the organic foreign matter is detected by the detection method of the present invention. The beta-alumina solid electrolyte produced using granulated powder or the like, which has been confirmed to be free of organic foreign matter, has a total of 2% when used in a sodium-sulfur battery.
It had a service life of 500 charge / discharge cycles or more.

When organic foreign matter is mixed,
When the beta-alumina solid electrolyte produced by using the granulated powder or the like after the removal by the organic foreign matter removal method of the present invention was used in a sodium-sulfur battery, all had a service life of 2500 charge / discharge cycles or more. .

[0034]

As described above, according to the present invention, it is possible to reliably separate and detect a small amount of organic foreign matter mixed in ceramic granulated powder, etc. Provided are a detection method and a method for removing an organic foreign substance that can reliably detect an organic foreign substance.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing one embodiment of a detection method and a removal method of the present invention.

FIG. 2 is a schematic explanatory diagram showing one embodiment of a detection method and a removal method of the present invention.

FIG. 3 is a schematic explanatory view showing a state in which droplets of a hydrophobic organic solvent in a suspension layer encapsulate an organic foreign substance;
(A) is a state in which the whole organic foreign substance is encapsulated, (b)
Indicates a state in which a part of the organic foreign substance is encapsulated.

FIG. 4 is an explanatory view showing one embodiment of a rotary blade of a stirrer usable in the present invention, wherein (a) is a top view and (b)
Is a side view.

FIG. 5 is an explanatory view showing another embodiment of the rotor of the stirrer which can be used in the present invention, wherein (a) is a top view and (b)
Is a side view.

FIG. 6 is a perspective view showing still another embodiment of the rotor of the stirrer which can be used in the present invention.

[Explanation of symbols]

1 ... water tank, 2 ... water, 3 ... hydrophobic organic solvent, 4 ... stirrer,
Reference numeral 5: rotating blades, 6: suspension layer, 7: droplets of a hydrophobic organic solvent, 8: container, 9: ceramic raw material powder or ceramic slurry or granulated powder, 10: vibrating feeder, 11: organic foreign matter, 12 ... Granulated powder or ceramic particles separated from organic foreign substances, 13 ... Rotary disk portion (13a: Disk lower surface portion, 13b: Disk upper surface portion, 13c: Disk notch portion), 14 ... Rotary blade blade (14a: wing protruding below the lower surface of the disk, 14b ... wing protruding above the upper surface of the disk).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 35/626-35/638 B01D 17/00 G01N 33/38

Claims (5)

(57) [Claims] 1. A method for detecting an organic foreign substance present in a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder, comprising a hydrophobic organic solvent layer having a specific gravity smaller than that of water and a water layer. The hydrophobic organic solvent layer of the two-layer solution is mixed in a suspended state with a stirrer to form a suspension layer, and then a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder is charged, and the mixture is stirred by the stirrer. After mixing the suspension state for a predetermined time, the ceramic raw material powder is characterized in that the suspension layer and the water layer are separated, and organic foreign matter mixed in the suspension layer is detected. A method for detecting the presence or absence and the amount of organic contaminants in ceramic slurry or ceramic granulated powder. 2. The method according to claim 1, wherein the hydrophobic organic solvent is 1-octanol. The method according to claim 1, wherein the presence or absence and the amount of the organic foreign substance in the ceramic raw material powder, the ceramic slurry, or the ceramic granulated powder are detected. . 3. The ceramic raw material powder according to claim 1, wherein after the introduction of the ceramic raw material powder, the ceramic slurry, or the ceramic granulated powder is completed, the stirring rotation speed of the stirrer is reduced continuously or stepwise. A method for detecting the presence or absence and the amount of organic foreign matter in ceramic slurry or ceramic granulated powder. 4. A stirrer for mixing and stirring a hydrophobic organic solvent and water in a suspended state is a stirrer having a structure in which stirring disks are attached to a disk, and a ceramic raw material powder and a ceramic slurry are provided on an upper surface of the disk. Or detecting the presence and amount of organic contaminants in the ceramic raw material powder, ceramic slurry, or ceramic granulated powder according to claim 1, wherein the ceramic granulated powder is added and dispersed in the suspension layer. how to. 5. A hydrophobic organic solvent layer of a two-layer solution comprising a layer of a hydrophobic organic solvent having a lower specific gravity than water and a layer of water is mixed in a suspended state with a stirrer to form a suspension layer. Forming
Next, a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder is charged, and a suspension state is mixed by the stirrer for a predetermined time to thereby remove organic foreign matter in the ceramic raw material powder, the ceramic slurry, or the ceramic granulated powder. Of a ceramic raw material powder, a ceramic slurry, or a ceramic granulated powder.