JP2791737B2 - Manufacturing method of sintered filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to a filter over for liquid filtration
It relates to a method of manufacturing, and more particularly forming an atomized powder into a cylindrical shape, a method of manufacturing a sintered filter over for liquid filtration sintered.

[0002]

2. Description of the Related Art A sintered filter for liquid filtration (hereinafter abbreviated as a sintered filter) formed by molding and sintering a metal powder such as stainless steel by an appropriate method is a chemical industry, a polymer industry, or the like.
It has been put into practical use as a filter for removing solid components in a liquid, such as impurities and dust, in various industrial fields such as the pharmaceutical and food industries. Usually, these sintered filters use an amorphous metal powder by a water spray method (hereinafter referred to as water atomized metal powder), and the filter layer has an infinite number of random shapes and dimensions generated between the powders. (Hereinafter referred to as pores) are distributed almost continuously. The average size of the pores is determined by the particle size of the water atomized powder used, the molding pressure, etc. In actual use, the average pore size is determined by the size of the solid in the processing solution. Has selected a sintered filter. In addition, as the shape of the filter, a so-called candle type molded into a cylindrical shape is used. Generally, the processing liquid passes from the outer peripheral side to the inner peripheral side of the filtration layer of the cylindrical filter. At that time,
The solid content in the treatment liquid is to be captured on the outer peripheral surface of the filtration layer. In addition, the filter is characterized by having excellent mechanical strength and heat resistance because it is made of metal,
Unlike a disposable thread-wound filter or the like, it is possible to perform backwash regeneration.

[0003]

However, in the case of filtering solids such as impurities from the processing solution, the conventional sintered filter traps solids in pores present in the filtration layer, so-called clogging. The tendency to produce phenomena is significant. The reason why this clogging phenomenon occurs is basically that the size and shape of pores present in the filtration layer made of water atomized powder are randomly distributed. In addition, it is considered that clogging hardly occurs if only the solid content is larger than the size of the pores present on the surface of the filtration layer, but the size of the solid content is actually distributed over a wide range from small to large. Therefore, a solid content smaller than the size of the pores present on the surface of the filtration layer is sucked into the filtration layer together with the treatment liquid, is captured by the micropores and the like that are continuous with the pores, and causes clogging. Things. When this clogging phenomenon becomes remarkable, the pressure loss (filtration resistance) of the filtrate increases, leading to a significant decrease in filtration efficiency. Furthermore, with the conventional sintered filter, once the clogging phenomenon occurs,
Even when backwashing from the inner peripheral side to the outer peripheral side of the filtration layer using high-pressure water or a high-pressure gas-liquid mixed phase flow, it is difficult to remove all of the solids trapped inside the filtration layer, Another problem is that the backwash regenerating property, which is a feature of this type of filter, is deteriorated.

[0004] The present invention has been made to solve the problems the prior art has, no clogging phenomenon of the filtration layer to provide a method for producing a sintered filter over with excellent backwash regenerative The purpose is to:

[0005]

In order to achieve the above object, the present invention provides a method for producing a metal powder by atomization alone or
A mixture of the atomized metal powder and a binder resin is formed.
Filling into a mold and forming into a cylindrical shape by isostatic pressing
Layer filtration layer forming step, and the obtained cylindrical molded body is temporarily removed after demolding.
A preliminary sintering step of sintering to form a porous cylinder;
Atomized gold with a particle size smaller than the size of the metal powder
Disperse powder in binder resin solution to make slurry
A slurry preparation step, and applying the slurry to the outside of the base filtration layer.
Skin that is precoated or applied around the circumference to form a skin filtration layer
Simultaneously with the layer filtration layer forming step and the thickness adjustment of this cortical filtration layer
Adjusting and smoothing step for smoothing the surface of the skin layer,
A resin component removal step of burning and removing the resin component in the bed filtration layer,
A process for sintering the entire porous cylinder provided with the cortical filtration layer
And a method for manufacturing a sintered filter.

[0006] The present invention also relates to the atomized metal powder.
Particle size of atomized metal powder with particle size smaller than particle size
Prepare multiple slurries manufactured by changing the
Slurry is applied to the outer periphery of the base filtration layer in order from the largest
Of the atomized metal powder dispersed in the cortical filtration layer
From the surface of the base filtration layer to the surface of the skin filtration layer
In a method of manufacturing a sintered filter which is sequentially reduced in size.

[0007] The present invention also relates to a method for producing gold by the atomizing method.
The metal powder is a water atomized metal powder;
Atomizing with a particle size smaller than the particle size of the metal powder
Metal powder, water atomized metal powder, gas atomized gold
The present invention relates to a method for producing a sintered filter which is a metal powder or a plasma atomized metal powder .

[0008] The present invention also relates to a method for dispersing in the cortical filtration layer.
The diameter of the atomized metal powder is determined by the pore diameter of the base filtration layer.
The method is for manufacturing a sintered filter having a size of 1/6 to 1/4 .

Various types of the atomized metal powder are known, but an amorphous water atomized metal powder is preferably used for the base filtration layer, and a water atomized metal powder or a spherical powder is preferably used for the cortical filtration layer. A gas atomized metal powder or a plasma atomized metal powder is preferably used. The water atomized metal powder has good moldability,
Gas atomized metal powder and plasma atomized metal powder have high filtration accuracy and are suitable for direct filtration. The reason why the particle size of the atomized metal powder dispersed in the cortical filtration layer is limited to 1/6 to 1/4 of the pore diameter of the base filtration layer is that the base filtration layer other than this size is used. This is because it is not possible to form a good bridge that covers the pores on the surface of.

[0010] The precoat referred to in the present invention means that the porous cylinder is mounted on an appropriate filtration device and filtered under appropriate conditions using a slurry instead of a treatment liquid, so that a predetermined surface of the cylinder is formed on the surface of the cylinder. A skin layer is formed to a thickness. In addition, examples of the coating method include a spraying method, a brush coating method, and a roller coating method.

[0011]

According to the method of manufacturing a sintered filter over the the present invention,
Since the particle size of the atomized metal powder dispersed in the slurry for forming the skin filtration layer is significantly smaller than the particle size of the atomized metal powder used for the base filtration layer, pores finer than the pores provided in the base layer are formed in the skin layer. It is formed.
For example, large pores existing on the surface of a base filtration layer formed using a water atomized metal powder having an average particle diameter of about 200 μm are about 50 μm, whereas atomization for forming a cortical filtration layer is large. According to the results of intensive studies by the present inventors, the metal powder has a particle size of about 10 μm, that is, a particle diameter of about 1/5 of the pore size of the base filtration layer is preferably used, and about 2 μm is used. Micropores are formed. As a result, when the skin filtration layer is provided using the slurry in which the atomized metal powder having the particle size is dispersed, the atomized metal powder forming the skin filtration layer is satisfactorily so as to cover the pores of the base filtration layer. Bridges can be formed. Therefore, it can be obtained by the production method of the present invention .
Are so sintered filter Most solids all solids into the pores of the internal base layer filtering layer on top which can be reliably caught in cortex filtration layer surface micro-holes are formed in the treatment liquid not caught Filter clogging is prevented.

The thickness of the cortical filtration layer is ideally desirably as thin as possible in terms of flow resistance. However, in order to form the cortical filtration layer uniformly on the entire surface of the base filtration layer, the thickness is required. Several pieces of atomized metal powder forming the skin, that is, several tens of μm are required. However, when it is difficult to form a uniform bridge with only a single layer of the skin due to the relationship between the required pore size of the skin and the size of the base layer, a slurry in which the particle size of the atomized metal powder is changed is used. Preparing several types, and then performing pre-coating or coating multiple times on the outer peripheral surface of the base layer in the order of the slurry with the largest particle size of the dispersed powder, the pores are sequentially reduced from the base layer surface side to the skin layer side, and the bridge on the base layer surface is also sure. Formed.

The pores of the cortical filtration layer are formed not only by the voids formed between the atomized metal powders of the cortical layer but also by the binder resin component (eg, cellulose resin, polyvinyl alcohol, etc.) of the precoated or applied slurry. There are also fine gaps generated by decomposition and burning in the minute removal step, which has the effect of substantially increasing the filtration performance of the skin layer.

[0014]

It will be described with reference to FIG method for manufacturing a sintered filter over the EXAMPLES present invention. Note that the present invention is not limited to the present embodiment. FIG. 1 shows a first embodiment of the manufacturing method of the present invention.
Perspective view of a sintered filter over obtained by, Figure 2 is a
FIG. 3 is a cross-sectional view of a sintered filter obtained according to one embodiment .
FIG. 4 is a cross-sectional view of a sintered filter obtained by the second embodiment of the manufacturing method of the present invention, FIG. 4 is a chart showing a method of manufacturing the sintered filter of the present invention, and FIG. It is a sectional view showing a molding die used in the method ,
(A) is a longitudinal sectional view, and (b) is a transverse sectional view of a tt portion.

Embodiment 1 Embodiment 1 will be described with reference to FIG. The mold used in the present invention includes an inner mold (hereinafter referred to as an inner mold) 4, an outer mold (hereinafter referred to as an outer mold) 5, a holding ring 6, and an upper lid 7. The inner mold 4 is made of a soft material, for example, a Shore hardness of 70.
Made of considerable urethane resin. The outer mold 5, the holding ring 6, and the upper lid 7 are made of stainless steel.

First, the inner die 4 and the outer die 5 are held by the lower holding ring 6a.
Assemble through. Next, a water atomized stainless steel powder having a particle size distribution of 200 to 250 μm is filled in the gaps (base layer filtration layer forming portion) 8 of the inner mold 4 and the outer mold 5, the upper holding ring 6 b is attached, and the upper lid 7 is attached. Next, after the molding die 9 is fixed to a holding table (not shown), the inner die 4 is pressed at 1000 kgf / cm from the direction of the arrow p by a hydrostatic pressing device (not shown).
^Form under pressure of ² . Next, the obtained cylindrical molded body was removed from the mold, and pre-sintered at 1000 ° C. for 30 minutes.
An average pore diameter of 40 μm and a porosity of 50% to become the base filtration layer 1
Was produced.

Further, in order to form the cortical filtration layer 2, a solution in which polyvinyl alcohol (PVA) as a binder is dissolved in a solvent of water and isopropyl alcohol has an average particle diameter of 1%.
A water atomized stainless steel powder of 0 μm is uniformly dispersed to prepare a slurry having a viscosity of about 70 cp. Next, the slurry was uniformly applied to the outer periphery of the base filtration layer 1 to a thickness of about 0.5 mm using a spraying machine, and dried to form a skin filtration layer 2. Next, the porous cylinder provided with the skin layer 2 was subjected to smoothing of the surface and adjustment of the thickness of the skin layer using a screver, and finally to a thickness of 0.2 mm. Next, the porous cylinder whose surface is smoothed and whose skin layer thickness is adjusted is placed in an air atmosphere.
Gradually raise the temperature to 500 ° C, hold for 3 hours,
A) was burned, followed by main sintering at 1300 ° C. for 60 minutes in a hydrogen atmosphere to obtain an outer diameter of 32 mmφ × inner diameter of 26 mmφ ×
A sintered filter 3 having a length of 600 mm and an average pore diameter of the skin layer of 2 μm was produced.

Embodiment 2 Embodiment 2 will be described with reference to FIG. First, a porous cylinder serving as a base filtration layer is produced in the same manner as in Example 1. Next, this porous cylinder was attached to a filtration device (not shown), and the same slurry as in Example 1 (however, the average particle diameter was 20 μm) was used.
m of water atomized stainless steel powder) was used instead of the filtrate, and the outer surface of the base filtration layer 1 was filtered for about 0.2 m.
m, and a first skin layer 2a is provided. Then, the same slurry as used in Example 1 is precoated on the outer periphery of the first skin layer 2a to a thickness of about 0.4 mm to provide a second skin layer 2b. Was. Next, the porous cylindrical body 1 provided with the skin layers 2a and 2b
In the same manner as in Example 1, the surface was smoothed and the thickness of the skin layer was adjusted using a screver, and finally a skin layer 2 having a thickness of 0.4 mm was obtained. Next, burning and main sintering of the resin component were performed in the same manner as in Example 1, and the outer diameter was 32 mm and the inner diameter was 26 mm.
A sintered filter 3 having φ × length of 600 mm and an average pore diameter of the skin layer of 3 μm was produced.

Characteristics Comparison Test The sintered filter obtained in Example 1 and an average particle size of 20
Table 1 shows the results of a comparative test of a sintered filter of the same size and a conventional type manufactured by only the isostatic press molding method using water atomized stainless steel powder of μm.

[0020]

[Table 1]

Backwash regeneration test The sintered filters of Example 1 and Comparative Example were tested for backwash regeneration. Table 2 shows the results. The filtration conditions were a stock solution SS concentration of 10 mg / l and a flow rate of 11.5 m / hr (constant).
Backwashing conditions were as follows: air pressure 5 kgf / cm ² , air volume 62.5 Nl / shot,
The test was performed with a water pressure of 1 l / shot and a differential pressure of 1 kgf / cm from the start of filtration.
The time until it became ² and the backwashing started was measured at the 0, 50 and 100th backwashing times.

[0022]

[Table 2]

As is clear from Tables 1 and 2, the sintered filter obtained by the production method of the present invention is lighter in weight, larger in porosity and has a flow rate characteristic of 2 compared to the conventional filter.
It can be seen that it is twice as good, and that the backwashing reproducibility is about twice as good.

[0024]

The filtration layer of the sintered filter obtained by the production method of the present invention comprises a base filtration layer and a skin filtration layer,
Micropores are formed in the skin layer, so almost all solids present in the treatment liquid can be reliably captured on the surface of the skin filtration layer, and solids are captured in the pores inside the base layer filtration layer. Since it is not performed, it is possible to prevent the occurrence of clogging. Further, it is possible to greatly improve the increase in filtration resistance, and it is extremely large that it contributes to improving the function of the sintered filter and expanding the application field.

[Brief description of the drawings]

1 is a perspective view showing a <br/> sintered filter over obtained by the first embodiment of the manufacturing method of the present invention.

FIG. 2 is a cross-sectional view of the sintered filter obtained according to the first embodiment.

FIG. 3 is obtained by a second embodiment of the manufacturing method of the present invention.
It is a cross-sectional view of a sintered filter.

FIG. 4 is a chart showing a method for manufacturing a sintered filter of the present invention.

FIG. 5 is a sectional view showing a molding die used in the method for manufacturing a sintered filter of the present invention. (A) is a longitudinal sectional view. (B) is a transverse sectional view of a tt portion.

[Explanation of symbols]

 Reference Signs List 1 base layer filtration layer 2 skin layer filtration layer 2a first skin layer filtration layer 2b second skin layer filtration layer 3 sintered filter 4 inner mold 5 outer mold 6 holding ring 6a lower holding ring 6b upper holding ring 7 top lid 8 gap (base filtration Layer forming part) 9 Mold p Hydrostatic pressure application direction t Cutting part

Claims (4)

(57) [Claims] Claims: 1. A single metal powder prepared by an atomizing method.
Represents a mixture of the atomized metal powder and a binder resin.
Fill into a mold and form into a cylinder by hydrostatic pressing
After the base layer filtration layer forming step and the obtained cylindrical molded body are removed from the mold.
A pre-sintering step of pre-sintering to form a porous cylinder;
Atomizing with a particle size smaller than the particle size of the metal powder
Disperse metal powder in binder resin solution to form slurry
A slurry preparation step, and applying the slurry to the base filtration layer.
Precoated or applied to the outer periphery to form a cortical filtration layer
Same as the step of forming the cortical filtration layer and adjusting the thickness of the cortical filtration layer.
Sometimes adjusting and smoothing the surface of the cortical layer,
Resin content removal process for burning and removing resin content in the cortical filtration layer
And sintering the entire porous cylinder provided with the cortical filtration layer
A sintered filter characterized by comprising
Production method. 2. The particle size of the atomized metal powder is smaller than that of the atomized metal powder.
Manufactured by changing the particle size of atomized metal powder with a large particle size
Prepare multiple slurries,
In order from the top of the base layer filtration layer,
The particle size of the atomized metal powder dispersed in the
Smaller in order from the superficial layer surface to the cortical filtration layer surface
The sintered filter according to claim 1, wherein
Production method. 3. The atomized metal powder according to claim 1, wherein said atomized metal powder is a water atomized metal powder, and said atomized metal powder has a particle size smaller than the particle size of said atomized metal powder.
3. The method for producing a sintered filter according to claim 1, wherein the powder is water atomized metal powder, gas atomized metal powder, or plasma atomized metal powder. 4. The particle size of the atomized metal powder dispersed in the cortical filtration layer is 1/1 of the pore diameter of the base filtration layer.
The size is set to 6 to 1/4.
4. The method for producing a sintered filter according to 2 or 3.