JP7709346B2 - Adsorbent packed column and liquid purification device - Google Patents

Description

The present invention relates to an adsorbent-packed column and liquid purification device that are particularly suitable for semiconductor manufacturing processes.

In order to reduce the concentration of metal impurities in organic solvents to the ppt level, ion exchange resins and ion adsorption membranes are effective in reducing metal impurities, and it is particularly effective to purify them in combination with a particulate removal filter to remove non-ionic particulate impurities (Patent Document 1).

On the other hand, when a non-conductive substance (such as an organic solvent or ultrapure water) or gas is passed through a PFA pipe or tube at a high flow rate, static electricity accumulates inside.
In particular, in semiconductor manufacturing processes, static electricity buildup in fluid circuits and static electricity discharge to the circuits must be avoided. However, semiconductor-grade organic solvents and ultrapure water contain almost no conductive substances, so static electricity easily builds up in fluid circuits, which is an issue.
For example, Patent Document 2 reports a technique in which a particulate removal filter is provided with electrical conductivity by incorporating conductive fluoropolymer threads (a mixture of carbon and PFA) inside the filter.

International Publication No. 2020/217911 Special table 2019-520197 publication

As previously mentioned, in semiconductor manufacturing processes, the buildup of static electricity in the fluid circuits and the avoidance of static discharge to the circuits are significant issues.
Although conductive particulate filters exist, there are no conductive columns or cartridges for purification using ion exchange resins.
One example of the configuration of a conductive column or cartridge is a column in which the inner surface of a stainless steel container is coated with a fluororesin, but this is not preferable because of its weight and poor usability. In addition, in semiconductor manufacturing processes, columns made of fluororesin are mainly used from the standpoint of cleanliness, so it is most preferable for the container filled with the ion exchange resin to be made of fluororesin.
SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide an adsorbent-packed column and a liquid purification apparatus which are highly clean, do not accumulate static electricity, and are particularly suitable for use in semiconductor manufacturing processes.

The above object can be achieved by the following [1] to [8].
[1] A column having a container filled with a porous adsorbent,
The container is formed of a fluororesin and has liquid passage holes on the upstream and downstream sides of the container , and a conductive material is provided on at least a portion of the outer surface of the container , and at least a portion of the conductive material is connected from the upper end to the lower end of the container .
[2] The adsorbent-packed column according to the above [1], wherein the fluororesin is a perfluoroalkoxyethylene polymer or polytetrafluoroethylene.
[3] The adsorbent-packed column according to [1] or [2], wherein the conductive material is one or more selected from the group consisting of carbon black, carbon fiber, graphite, coke and metal fine powder.
[4] The adsorbent-packed column according to any one of [1] to [3], wherein the adsorbent is one or more selected from the group consisting of an ion exchanger, a zeolite, an activated carbon, and a synthetic adsorbent.
[5] The adsorbent-packed column according to any one of [1] to [4], further comprising joints for connecting to other members on the upstream and downstream sides of the container, the joints having a member for preventing the adsorbent from flowing out.
[6] The adsorbent-packed column according to any one of [1] to [5] above, which is in a cartridge form.
[7] A liquid purification apparatus comprising an adsorbent-packed column according to any one of [1] to [6].
[8] The liquid purification apparatus according to [7] above, which has a filter for capturing fine particles.

The present invention provides an adsorbent-packed column and liquid purification device that are highly clean, do not accumulate static electricity, and are particularly suitable for semiconductor manufacturing processes.

FIG. 1 shows a schematic diagram of an adsorbent-packed column according to one embodiment of the present invention. FIG. 2 is a schematic exploded view showing a joint portion between a container and a joint in the adsorbent-packed column shown in FIG. FIG. 3 is a schematic diagram showing an exploded view of a joint in the adsorbent-packed column shown in FIG. 5A is a schematic diagram showing an exploded view of a joint of an embodiment of an outflow prevention member different from that of FIG. 3, and FIG. 5B is a front view of the outflow prevention part (batten) constituting the joint shown in FIG. FIG. 5 is a schematic exploded view of a joint between a container and a joint in an adsorbent-packed column according to another embodiment of the present invention, the joint having a different configuration from that in FIG. FIG. 6 shows a schematic diagram of an adsorbent-packed column according to another embodiment of the present invention, which has a different configuration from that shown in FIG. 1 with respect to the conductive material. FIG. 7 shows a schematic diagram of an adsorbent-packed column according to another embodiment of the present invention, which has a different configuration from that shown in FIG. 1 with respect to the conductive material.

The adsorbent-packed column of the present invention can be suitably used, if necessary, in combination with a particulate capture filter to purify non-conductive substances (such as organic solvents and ultrapure water) or gases, particularly when attached to a liquid purification device, to obtain pure water, ultrapure water, or treated water in a preliminary stage to obtain the pure water. The adsorbent-packed column attached to a liquid purification device can purify the liquid by passing the liquid to be purified through the column, thereby adsorbing impurities to the adsorbent in the column. In the present invention, "pure water" generally refers to water with a resistivity (25°C) of 0.1 MΩ·cm or more, and "ultrapure water" refers to water with a resistivity of more than 15 MΩ·cm or more than 18 MΩ·cm.

The liquid to be purified (water to be treated) by the liquid purification device equipped with an adsorbent packed column is arbitrary and may be water or an aqueous solution, or may be an organic solvent (non-aqueous liquid) such as IPA (isopropyl alcohol), PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), PGEE (propylene glycol monoethyl ether), etc. The liquid to be purified may be water or a mixture of the organic solvents, a solution in which a polymer or the like is dissolved in water or a solvent, or an acid or alkaline aqueous solution. Alternatively, the liquid purification device may be used, for example, as a household water purifier for obtaining purified water at home.

Below, a form for carrying out the present invention (hereinafter, referred to as an embodiment) will be described with reference to the drawings. However, the present invention is not limited to this embodiment.

FIG. 1 is a schematic diagram of an adsorbent-packed column 1 according to one embodiment of the present invention, FIG. 2 is a schematic diagram showing an exploded view of a joint between a container and a joint in the adsorbent-packed column shown in FIG. 1, and FIG. 3 is a schematic diagram showing an exploded view of the joint in the adsorbent-packed column shown in FIG. 1.
As shown in FIG. 1, an adsorbent-packed column 1 includes a porous adsorbent 2 and a fluororesin container 3 packed with the adsorbent 2.
The upstream and downstream sides of the container 3 are provided with liquid passage holes 7, 8 through which the liquid to be purified passes. For example, the flow may be a downflow type in the direction shown by the arrow in FIG. 1, i.e., the liquid to be purified is supplied from the upstream side of the column container 3 through the liquid passage hole 7, purified in the column container 3, and the liquid is discharged from the downstream liquid passage hole 8, or the flow may be an upflow type in the direction opposite to the arrow in FIG. 1, i.e., the liquid to be purified is supplied from the downstream liquid passage hole 8 of the column container 3, purified in the column container 3, and the liquid to be purified is discharged through the upstream liquid passage hole 7.
The joining of the column container 3 with the joint 5 for joining to other members is not particularly limited, but for example, as shown in Figures 1 and 2, a sleeve 9 is inserted into the upstream side and downstream side of the column container 3, respectively, and the upstream side and downstream side of the column container 3 can be joined to the joint 5 by the joint 5 and nut 6. As an example of such a joint, as shown in Figure 3, there is an embodiment in which two threaded parts 52 and 53 are sandwiched between them and an outflow prevention member 51 for the adsorbent is sandwiched. The outflow prevention member 51 for the adsorbent is formed of a mesh plate 511 and a mesh 512, thereby preventing the outflow of the adsorbent 2. The sizes of the threaded parts 52 and 53 are appropriately adjusted as necessary, and may be the same size or different sizes.
The mesh plate 511 forming the adsorbent outflow prevention member 51 is installed to hold and fix the mesh 512, and has holes of a size that does not hinder the flow of the liquid to be purified. On the other hand, the mesh 512 is installed to prevent the outflow of the adsorbent packed in the column, and the mesh opening is preferably 30 to 350 μm. Depending on the particle size of the adsorbent packed in the column, as shown in FIG. 4, a mesh may not be provided, and only the mesh plate 511 with slit-shaped or lattice-shaped gaps may be used to prevent the outflow of the adsorbent. The opening of the slits and lattice is preferably 1/2 or less of the average particle size of the adsorbent.
As shown in FIG. 5, the column container 3 and the joint 5 can be joined by flaring the upstream and downstream tip portions 31 of the column container (heating the tip portions 31 with a heat gun to a temperature at which the tip portions 31 are plastically deformed), and pressing the joint 5, which has an outflow prevention member 51 for the adsorbent at one end, into the inside of the tip portion 31 at the timing when the tip portion 31 of the column container 3 is plastically deformed, to join the column container 3 to the joint 5. The tip 31 of the column container 3 is widened by the flaring, so that the nut is prevented from falling off. In this case, the mesh plate 511 and the mesh 512 constituting the outflow prevention member 51 of the joint 5 must both be of a size that can fit inside the flared column container 3. A screw portion 54 for connecting to another member may be provided on the opposite side of the outflow prevention member 51 of the joint 5. The threaded portion 54 may be configured integrally with the joint 5 or may be separable from the joint 5, and is not particularly limited.
The column container 3 has a conductive material 4. The conductive material 4 provided in the column container 3 prevents the accumulation of static electricity that is generated when a non-conductive material (such as an organic solvent or ultrapure water) or gas flows at a high flow rate through the column container 3 made of a fluororesin.
The conductive material 4 may be provided on at least a part or the whole of the outer surface of the column container 3, or may be contained in the fluororesin forming the column container 3, or may be both. However, it is necessary that the conductive material does not come into contact with the target to be purified flowing through the column container 3.
The conductive material 4 may be provided on at least a part of the outer surface of the column container 3 in a stripe pattern as shown in FIG. 6 or in a ladder pattern as shown in FIG . 7. The conductive material 4 may be provided in any pattern without particular limitation.

The porous adsorbent 2 may be one selected from the group consisting of ion exchangers, zeolites, activated carbon, and synthetic adsorbents, or may be a combination of two or more selected from the group consisting of ion exchangers, zeolites, activated carbon, and synthetic adsorbents.

Examples of ion exchangers include granular ion exchange resins such as granular cation exchange resins, granular chelate resins, granular anion exchange resins, and combinations of granular cation exchange resins, granular chelate resins, and granular anion exchange resins; monolithic organic porous cation exchangers, monolithic organic porous chelate exchangers, monolithic organic porous anion exchangers, and monolithic organic porous ion exchangers such as combinations of monolithic organic porous cation exchangers, monolithic organic porous chelate exchangers, and monolithic organic porous anion exchangers; and combinations of granular ion exchange resins and monolithic organic porous ion exchangers. When the ion exchanger is a combination of a granular cation exchange resin, a granular chelate exchange resin, and a granular anion exchange resin, it may be used as a mixed bed in which the granular cation exchange resin, the granular chelate exchange resin, and the granular anion exchange resin are uniformly mixed, or it may be used as a double bed in which the upstream side of the ion exchanger-packed region is packed with a granular cation exchange resin and/or a granular chelate exchange resin, and the downstream side of the ion exchanger-packed region is packed with a granular anion exchange resin, or the upstream side of the ion exchanger-packed region is packed with a granular anion exchange resin, and the downstream side of the ion exchanger-packed region is packed with a granular cation exchange resin and/or a granular chelate exchange resin. In addition, when the ion exchanger is a combination of a monolithic organic porous cation exchanger and a monolithic organic porous anion exchanger, the upstream side of the ion exchanger packing region is filled with a monolithic organic porous cation and/or a monolithic organic porous chelate exchanger, and the downstream side of the ion exchanger packing region is filled with a monolithic organic porous anion exchanger, or the upstream side of the ion exchanger packing region is filled with a monolithic organic porous anion exchanger, and the downstream side of the ion exchanger packing region is filled with a monolithic organic porous cation exchanger and/or a monolithic organic porous chelate exchanger. When the ion exchanger is a combination of a granular ion exchange resin and a monolithic organic porous ion exchanger, the upstream side of the ion exchanger packing region is filled with a monolithic organic porous ion exchanger, and the downstream side of the ion exchanger packing region is filled with a granular ion exchange resin.

The granular cation exchange resin may be a strong acid cation exchange resin, a weak acid cation exchange resin, a chelating resin, or a combination of these. Examples of strong acid cation exchange resins include Orlite DS-1, Orlite DS-4, XSC-1415HG, etc. Examples of weak acid cation exchange resins include Amberlite (registered trademark) IRC76, etc. Examples of chelating resins include Orlite DS-21, DS-22, etc. In order to reduce cationic impurities in the treated liquid, it is desirable to use the cation exchange resin in the H form.

The granular anion exchange resin may be a strongly basic anion exchange resin, a weakly basic anion exchange resin, or a combination of these. Examples of strongly basic anion exchange resins include Orlite DS-2, Orlite DS-5, and XSA-2415HG. Examples of weakly basic anion exchange resins include Orlite DS-6, and examples of boron-selective anion exchange resins with glucamine groups as functional groups include Amberlite (registered trademark) IRA743. In order to reduce anionic impurities in the treated liquid, it is desirable to use the anion exchange resin in the OH form. However, if carbonic acid does not become an impurity, it can be used in the carbonate or bicarbonate form.

The ion exchanger may also be a mixed bed ion exchanger. Examples of mixed bed ion exchange resins that are a mixture of granular strongly acidic cation exchange resins (cation exchange resins) and granular strongly basic anion exchange resins (anion exchange resins) include Orlite DS-3, Orlite DS-7, and XSM-N411HG.

The average particle size of the granular ion exchanger is not particularly limited, but is preferably 200 to 1000 μm, and particularly preferably 300 to 800 μm. The average particle size of the ion exchanger is a value measured by a laser diffraction particle size distribution measuring device.

There are no particular limitations on the monolithic organic porous ion exchanger, so long as the monolithic organic porous material has an ion exchange group introduced therein. For example, the monolithic organic porous ion exchanger shown below can be used.

Examples of monolithic organic porous ion exchangers include monolithic organic porous ion exchangers (hereinafter also referred to as the first form of monolithic organic porous ion exchanger) that are composed of a continuous skeleton phase and a continuous pore phase, the thickness of the continuous skeleton being 1 to 100 μm, the average diameter of the continuous pores being 1 to 1000 μm, the total pore volume being 0.5 to 50 mL/g, cation exchange groups or anion exchange groups being introduced, the ion exchange capacity per weight in a dry state being 1 to 6 mg equivalents/g, and the ion exchange groups being uniformly distributed in the organic porous ion exchanger.

The first form of monolithic organic porous ion exchanger may be a monolithic organic porous ion exchanger in which the air bubble-like macropores overlap each other, forming a continuous macropore structure with the overlapping portions forming openings with an average diameter of 30 to 300 μm, the total pore volume being 0.5 to 10 ml/g, cation exchange groups or anion exchange groups being introduced, the ion exchange capacity per weight in the dry state being 1 to 6 mg equivalents/g, the ion exchange groups being uniformly distributed in the organic porous ion exchanger, and in an SEM image of a cut surface of the continuous macropore structure (dried body), the area of the framework portion appearing in the cross section is 25 to 50% of the image area.

In addition, the monolithic organic porous ion exchanger of the first embodiment is a monolithic organic porous ion exchanger that is a bicontinuous structure consisting of a three-dimensionally continuous skeleton with an average thickness of 1 to 60 μm made of an aromatic vinyl polymer containing 0.1 to 5.0 mol % of crosslinked structural units among all structural units to which ion exchange groups have been introduced, and three-dimensionally continuous pores with an average diameter of 10 to 200 μm between the skeletons, has a total pore volume of 0.5 to 10 mL/g, has cation exchange groups or anion exchange groups introduced, has an ion exchange capacity per weight in a dry state of 1 to 6 mg equivalents/g, and has ion exchange groups uniformly distributed in the organic porous ion exchanger.

When the particles are made of ion exchangers, the liquid to be treated is, for example, IPA (isopropyl alcohol), PGMEA (propylene glycol monomethyl ether acetate), PGME (propylene glycol monomethyl ether), PGEE (propylene glycol monoethyl ether), or NMP (N-methyl-2-pyrrolidone). An aqueous solution exhibiting acidity to alkalinity may be used as the liquid to be treated. Impurities to be removed from the liquid to be treated are, for example, metal ions such as Li, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Cd, and Pb, anions such as Cl, SO ₄ , NO ₃ , PO ₄ , CO ₃ , and HCO ₃ , organic acids such as formic acid, acetic acid, maleic acid, and propionic acid, and polymer compounds having positive or negative charges.

The zeolite may be, for example, one or more types selected from crystalline zeolites.
The crystalline zeolite may be one or more crystalline zeolites selected from A-type, Y-type, X-type, chabazite, ferrierite, ZSM-5, clinoptilolite, and the like.

Furthermore, the crystalline zeolite preferably has a Si/Al molar ratio of 1 to 5. With a Si/Al molar ratio within the above range, the crystalline zeolite is structurally stable and has an appropriate cation content, allowing it to adsorb and remove impurities from the liquid to be treated.

The crystalline zeolite may have cations exchanged with lithium ions, calcium ions, or the like, or may not have cations exchanged.

The above-mentioned crystalline zeolite is preferably spherical or cylindrical, and preferably has a diameter of 0.5 to 5 mm.
When the diameter of the crystalline zeolite is within the above range, the liquid to be treated (the fluid) can be suitably impregnated therein without deteriorating the handling properties.

Activated carbon is commercially available activated carbon. The diameter of the activated carbon particles is arbitrary. Activated carbon has micropores with diameters of, for example, 0.7 nm to several tens of μm, and can physically remove organic impurities (organic acids, pigments, oils, etc.) from the liquid to be treated. In addition, chlorine can be decomposed using the carbon component in the activated carbon. Examples of activated carbon include carbonized phenolic resin. Carbonized synthetic adsorbents and ion exchangers may also be used as activated carbon.

Examples of synthetic adsorbents include styrene-divinylbenzene-based adsorbents, acrylic-based adsorbents, and phenol-based adsorbents. Commercially available products can also be used for these adsorbents. Commercially available products are not particularly limited, but include, for example, synthetic adsorbents XAD2000, XAD4, FPX66, XAD1180N, XAD7HP, and XAD-2 (all trade names, manufactured by Organo Corporation), AMBERLITE (registered trademark, manufactured by DuPont), Diaion (registered trademark) HP20, HP21, Sepabeads (registered trademark) SP850, SP825L, and SP700 (all trade names, manufactured by Mitsubishi Chemical Corporation), and carbonized phenolic resin (manufactured by MET Co., Ltd.).

Examples of fluororesins that can be used to form the container include perfluoroalkoxyethylene polymer (PFA), polytetrafluoroethylene (PTFE), polytrifluorochloroethylene, copolymers of tetrafluoroethylene and perfluoroalkyl vinyl ether, copolymers of tetrafluoroethylene and hexafluoropropylene, and ternary copolymers of tetrafluoroethylene, fluoroalkyl vinyl ether, and hexafluoropropylene. Among these, PFA and PTFE are particularly preferred because of their excellent heat resistance and chemical resistance.

The conductive material is preferably a conductive material with low gas permeability, and in particular, it is preferable that impurities and volatile substances in the gas, ammonia, moisture, hydrofluoric acid, etc., are prevented from dissolving into the tube. From this viewpoint, one or more types selected from the group consisting of carbon black, carbon fiber, graphite, coke, and fine metal powders are used. Examples of fine metal powders include boron nitride, copper, silver, etc.

The adsorbent-packed column of the present invention described above can be constructed by the following method.
That is, a commercially available PFA pipe or tube (not containing conductive material) of the required length is prepared and filled with an adsorbent. Next, sleeves are inserted into the upstream and downstream sides of the PFA pipe or tube using an appropriate jig.
After inserting the sleeve, a tube cover containing a conductive material (conductive tube cover) is attached from above the PFA pipe or tube. This conductive tube cover can be substituted by attaching a conductive film or wrapping a conductive band. Alternatively, the work of attaching the conductive tube cover can be omitted by using a PFA pipe or tube having a conductive material on the inside and/or outside surface.
The sleeve may be inserted after the conductive tube cover is attached.
Then, the construction can be completed by tightening the threaded portion of the joint having the outflow prevention member 51 for the adsorbent as shown in FIG. 3 or 4 with a nut.
The adsorbent-packed column of the present invention can also be provided in the form of a cartridge.

The adsorbent-packed column of the present invention obtained by the above construction method does not accumulate static electricity inside, even though it uses fluororesin, particularly in the semiconductor manufacturing process, and because it is made of fluororesin, it is very clean and easy to handle.

REFERENCE SIGNS LIST 1: adsorbent-packed column 2: adsorbent 3: container 31: tip of container 4: conductive material 5: joint 6: nut 7: sleeve 8, 9: liquid passage hole 51: member for preventing outflow of adsorbent 52, 53, 54: threaded portion 511: mesh plate 512: mesh

Claims (8)

A column having a container filled with a porous adsorbent,
The container is formed of a fluororesin and has liquid passage holes on the upstream and downstream sides of the container , and a conductive material is provided on at least a portion of the outer surface of the container , and at least a portion of the conductive material is connected from the upper end to the lower end of the container . The adsorbent-packed column according to claim 1, wherein the fluororesin is a perfluoroalkoxyethylene polymer or polytetrafluoroethylene. The adsorbent-packed column according to claim 1 or 2, wherein the conductive material is one or more selected from the group consisting of carbon black, carbon fiber, graphite, coke, and metal fine powder. The adsorbent-packed column according to any one of claims 1 to 3, wherein the adsorbent is one or more selected from the group consisting of ion exchangers, zeolites, activated carbon, and synthetic adsorbents. The adsorbent-packed column according to any one of claims 1 to 4, which has joints on the upstream and downstream sides of the container for connecting to other members, and the joints have a member for preventing the adsorbent from leaking out. The adsorbent-packed column according to any one of claims 1 to 5, which is in a cartridge form. A liquid purification apparatus comprising an adsorbent-packed column according to any one of claims 1 to 5. The liquid purification device according to claim 7, which has a filter for capturing fine particles.