Filter, method for removing metal ions, and metal ion removing device

Abstract

When water having an electric specific resistance value of 18M Ω cm or more is passed through the filter at a space speed of 1200hr - 1, the electric specific resistance value of the water after the passage is 13M Ω cm or more.SOLUTION: To provide a filter capable of efficiently removing metal ions in a liquid to be treated and capable of easily obtaining a solution extremely low in metal ion content.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a filter, a method for removing metal ions, and an apparatus for removing metal ions. [Background technology]

[0002] There has been a demand for solutions with low metal ion content for use in the manufacture of electronic components such as integrated circuits. For example, Patent Document 1 describes a metal compound removal device that reduces the metal content in surfactants to the ppb level, making them suitable for use in high-performance semiconductor materials. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-213200 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, electronic components have become increasingly dense. As the line width narrows with increasing density, even small amounts of impurities can have adverse effects. Therefore, to ensure stability, the allowable metal ion content in solutions used in electronic component manufacturing has become even lower, and it is expected that metal ions will be removed to levels even lower than the ppb level. However, conventional methods have sometimes been difficult to sufficiently reduce the metal ion content or required numerous work steps, making them inefficient.

[0005] An object of the present invention is to provide a filter that can efficiently remove metal ions from a liquid to be treated, making it possible to easily obtain a solution with an extremely low metal ion content. Another object of the present invention is to provide a method for removing metal ions and a metal ion removal device that use the filter. [Means for solving the problem]

[0006] One aspect of the present invention is a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder, and is sintered by sintering water having an electrical resistivity of 18 MΩ·cm or more at a space velocity of 1200 h -1 The present invention relates to a filter that, when passed through the filter, has an electrical resistivity of 13 MΩ·cm or more after passing water through the filter.

[0007] The filter is formed using a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder, and thus the filter can efficiently remove metal ions from the liquid to be treated.

[0008] In one embodiment, the ratio d2 / d1 of the average particle diameter d2 of the activated carbon powder to the average particle diameter d1 of the thermoplastic resin powder may be equal to or less than 10. This makes it easier for the thermoplastic resin powder particles to fuse together, which tends to further improve the uniformity, strength, and density of the porous molded body.

[0009] In one embodiment, the activated carbon powder may have an average particle diameter d2 of 100 μm or less. This increases the surface area of ​​the activated carbon in the porous molded body, allowing for more efficient removal of metal ions from the liquid to be treated. Furthermore, by reducing the average particle diameter d2 of the activated carbon powder, the activated carbon powder becomes more susceptible to cleaning and other processes, making it easier to obtain a filter that meets the above-mentioned electrical resistivity requirements.

[0010] Another aspect of the present invention relates to a method for removing metal ions from a liquid to be treated, the method comprising a liquid passing step of passing the liquid to be treated through the above-described filter.

[0011] In one embodiment, the liquid passing step may include a first liquid passing step of passing the liquid to be treated through a first filter, and a second liquid passing step of passing the liquid to be treated that has passed through the first liquid passing step through a second filter. In this case, the second filter may be the filter according to one aspect of the present invention.

[0012] In the above aspect, the first filter may include a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder.

[0013] Yet another aspect of the present invention relates to a metal ion removal device comprising a first filter and a second filter that removes metal ions from the treated liquid that has passed through the first filter, wherein the second filter is the filter according to the above-mentioned aspect of the present invention.

[0014] In one embodiment, the first filter may include a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder. [Effects of the Invention]

[0015] The present invention provides a filter that can easily remove metal ions from a liquid to be treated, thereby producing a solution with an extremely low metal ion content. The present invention also provides a method for removing metal ions and a metal ion removal device that use the filter. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 illustrates an embodiment of a metal ion removal device. [Figure 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 10 is a diagram showing another embodiment of the metal ion removal device. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Note that the drawings are partially exaggerated for ease of understanding, and the dimensional ratios and the like are not limited to those shown in the drawings.

[0018] <filter> The filter according to this embodiment includes a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder.

[0019] The filter according to this embodiment can also filter water with an electrical resistivity of 18 MΩ·cm or more at a space velocity of 1200 h -1 This filter is characterized in that when a liquid is passed through the filter, the electrical resistivity of the water after passing through the filter is 13 MΩ·cm or more. The electrical resistivity of the water before passing through the filter may be 18 MΩ·cm or more, and may be the theoretical limit of approximately 18.23 MΩ·cm. There is no particular upper limit to the electrical resistivity of the water after passing through the filter, and it may be, for example, equal to or less than the electrical resistivity of the water before passing through the filter.

[0020] In this specification, the electrical resistivity of water is a value measured using an in-line resistivity sensor ERF-001-CT manufactured by Horiba, Ltd.

[0021] The above filter can remove metal ions from the liquid to be treated, making it possible to easily obtain a solution with an extremely low metal ion content from the liquid to be treated that contains metal ions.

[0022] In this embodiment, the sintered product may have a strength that allows it to stand on its own, and the thermoplastic resin powder particles may be fused together and fixed.

[0023] In this embodiment, the activated carbon powder is activated carbon processed into a powder form. Activated carbon can be obtained by reacting activated carbon raw materials such as wood, bamboo, coconut shells, rice husks, bituminous coal (coal), lignite (lignite), peat, olive pits, rayon, acrylonitrile, coal pitch, petroleum pitch, and phenolic resin at high temperatures with steam, chemicals, and the like to make the activated carbon porous.

[0024] The activated carbon powder may contain carbon as a main component. The activated carbon powder may further contain oxygen, hydrogen, calcium, etc. in addition to carbon. Here, the term "main component" refers to a content of 50% by mass (preferably 80% by mass or more, more preferably 90% by mass or more).

[0025] The average particle diameter d2 of the activated carbon powder may be, for example, 1 μm or more, or may be 10 μm or more. The average particle diameter d2 of the activated carbon powder may be, for example, 1000 μm or less, preferably 500 μm or less, and more preferably 100 μm or less. By reducing the average particle diameter d2 of the activated carbon powder, the surface area of ​​the activated carbon in the porous molded body increases, allowing for more efficient removal of metal ions from the liquid to be treated. Furthermore, by reducing the average particle diameter d2 of the activated carbon powder, the activated carbon powder becomes more susceptible to cleaning and other processes, making it easier to obtain a filter that meets the above-mentioned electrical resistivity requirements.

[0026] The average particle diameter d2 of activated carbon powder refers to the value D50 determined by the laser diffraction / scattering method in accordance with JIS Z 8825: 2013. More specifically, the particle size distribution of the activated carbon powder is determined by the laser diffraction / scattering method using a Mastersizer 3000 manufactured by Malvern Instruments (Worcester, UK), and the average particle diameter d2 is defined as D50, where the number of particles reaches 50% of the total, calculated from the smallest particles.

[0027] The specific surface area of ​​activated carbon powder is, for example, 100m 2 / g or more, preferably 500m 2 / g or more. The specific surface area of ​​the activated carbon powder is, for example, 5000 m 2 / g or less, and 2 / g or less. By increasing the specific surface area of ​​the activated carbon powder, metal ions in the liquid to be treated can be removed more efficiently. The specific surface area of ​​the activated carbon powder is the value measured by the BET method (also called the BET specific surface area).

[0028] In this embodiment, the thermoplastic resin powder is a powder made of a resin material containing a thermoplastic resin as a main component, and can be partially fused together by sintering to form a porous structure.

[0029] The content of the thermoplastic resin in the thermoplastic resin powder is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, based on the total amount of the thermoplastic resin powder.

[0030] The thermoplastic resin powder may further contain components other than the thermoplastic resin, such as a plasticizer such as a stearate, talc, silica, an antioxidant, etc.

[0031] The thermoplastic resin powder preferably contains at least one thermoplastic resin selected from the group consisting of ultra-high molecular weight polyethylene, polyamide, fluororesin, and acrylic resin.

[0032] Ultra-high molecular weight polyethylene has a weight average molecular weight of 7.5 x 10 5 g / mol or more 5×10 7 g / mol or less is preferred, and 1.0×10 6 g / mol or more 1.2×10 7 The weight average molecular weight of the ultra-high molecular weight polyethylene is a value measured by the following method. 1."StandardTest Method for Dilute Solution Viscosity of Ethylene Polymers," D1601, Annual Book of ASTM Standards, American Society forTesting and Materials. 2."StandardSpecification for Ultra-High-Molecular-Weight PolyethyleneMolding and ExtrusionMaterials," D4020, Annual Book of ASTM Standards,American Society forTesting and Materials

[0033] The melting point of the ultra-high molecular weight polyethylene is not particularly limited and may be, for example, 130° C. to 135° C. The melt index of the ultra-high molecular weight polyethylene is preferably 1.0 g / 10 min or less (ASTM D1238 (ISO1133), 190° C., load 21.6 kg) or less, and more preferably 0.5 g / 10 min or less.

[0034] As the polyamide, for example, semi-crystalline polyamide fine particles having a melting point of 150° C. to 200° C. can be suitably used. Furthermore, such polyamides preferably have an average of 10 or more carbon atoms per monomer unit.

[0035] The average particle diameter d1 of the thermoplastic resin powder is not particularly limited and may be, for example, 0.5 μm or more, or 1 μm or more. The average particle diameter d1 of the thermoplastic resin powder may be, for example, 500 μm or less, or 100 μm or less. Increasing the average particle diameter of the thermoplastic resin powder tends to increase the gaps in the porous molded body, improving liquid permeability, while decreasing the average particle diameter tends to make the porous molded body denser, further improving strength. The average particle diameter d1 of the thermoplastic resin powder can be measured using a method similar to that for measuring the average particle diameter d2 of the activated carbon powder.

[0036] The thermoplastic resin powder is preferably a non-spherical resin powder. The thermoplastic resin powder may have, for example, a shape in which small spherical particles are aggregated like a bunch of grapes, or a shape in which multiple protrusions are formed on spherical particles like confetti. Non-spherical thermoplastic resin powders tend to have even better resistance to dimensional changes during swelling.

[0037] The thermoplastic resin powder is preferably a porous powder. The bulk density of the porous thermoplastic resin powder is, for example, 0.1 to 0.7 g / cm. 3 and may be 0.2 to 0.6 g / cm 3 In this specification, the bulk density of the porous thermoplastic resin powder is a value measured by a method in accordance with ISO60.

[0038] The ratio d2 / d1 of the average particle diameter d2 of the activated carbon powder to the average particle diameter d1 of the thermoplastic resin powder may be, for example, 0.1 or greater, or even 0.5 or greater. The ratio d2 / d1 of the average particle diameter d2 of the activated carbon powder to the average particle diameter d1 of the thermoplastic resin powder may be, for example, 1000 or less, preferably 100 or less, and more preferably 10 or less. By reducing the ratio d2 / d1 of the average particle diameter d2 of the activated carbon powder to the average particle diameter d1 of the thermoplastic resin powder, the thermoplastic resin powders tend to fuse more easily, which tends to improve the uniformity, strength, and density of the porous molded body. This further improves the strength of the porous molded body, making it more suitable for use as a self-supporting filter.

[0039] In this embodiment, the porous compact is formed by sintering a mixed powder containing activated carbon powder and thermoplastic resin powder.

[0040] In one embodiment, the porous molded body can be said to be a porous structure formed by sintering a thermoplastic resin powder, in which activated carbon powder is dispersed and fixed.

[0041] The content of the activated carbon powder in the mixed powder is preferably 10 parts by mass or more, more preferably 25 parts by mass or more, per 100 parts by mass of the thermoplastic resin powder, and is preferably 900 parts by mass or less, more preferably 300 parts by mass or less, per 100 parts by mass of the thermoplastic resin powder.

[0042] The mixed powder may further contain additives other than the activated carbon powder and the thermoplastic resin powder. For example, the mixed powder may further contain a dry gel, a heavy metal reducing medium, an arsenic removing medium, an antimicrobial medium, an ion exchange medium, an iodized resin, a fiber, a gas adsorption medium, etc. The content of such additives is preferably 20% by mass or less, more preferably 5% by mass or less, based on the total amount of the mixed powder.

[0043] In this embodiment, the mixed powder is filled into a mold or the like according to the desired shape of the porous molded body, and then sintered. The sintering of the mixed powder can be carried out under conditions that cause fusion of the thermoplastic resin powder.

[0044] The sintering temperature can be, for example, a temperature equal to or higher than the melting point of the thermoplastic resin in the thermoplastic resin powder. The sintering temperature may be, for example, 140°C or higher, and preferably 150°C or higher. The sintering temperature may also be, for example, 200°C or lower, or 180°C or lower.

[0045] The sintering time is not particularly limited and can be, for example, 5 to 120 minutes, or may be 10 to 60 minutes.

[0046] The porous compact can be formed into various shapes by appropriately selecting a mold for filling the mixed powder during sintering, such as a disk, hollow cylinder, bell, cone, hollow star, etc.

[0047] The thickness of the porous molded body may be, for example, 0.2 mm or more, preferably 1 mm or more, more preferably 5 mm or more, and may be, for example, 1000 mm or less, preferably 100 mm or less.

[0048] The porous compact may be a sintered product of the mixed powder.

[0049] The filter according to the present embodiment includes the porous molded body. The filter according to the present embodiment may be a filter made of the porous molded body, and may further include other components, etc., as long as the filter can sufficiently remove metal ions.

[0050] The shape of the filter according to this embodiment is not particularly limited, and may be, for example, a cylindrical, prismatic, plate-like, bell-like, spherical, hemispherical, rectangular, or the like, and these may be hollow.

[0051] As described above, the filter according to this embodiment can filter water having an electrical resistivity of 18 MΩ·cm or more at a space velocity of 1200 h -1 The filter is characterized in that when water is passed through it, the electrical resistivity of the water after passing through it is 13 MΩ·cm or more.

[0052] The method for obtaining such a filter is not particularly limited, but examples thereof include a method in which a cleaning liquid is passed through the porous molded body to clean the porous molded body. Examples of the cleaning liquid that can be used include water, an organic solvent, an acidic solution, a basic solution, and a mixture thereof. The cleaning conditions are not particularly limited, and for example, the flow rate during cleaning may be 10 mL / min to 10 L / min, and the space velocity during cleaning may be 6 to 6,000 h . -1 The temperature of the cleaning liquid during cleaning may be, for example, 1°C to 99°C.

[0053] <Metal ion removal method> The method for removing metal ions according to this embodiment is a method for removing metal ions from a liquid to be treated, and includes a liquid passing step of passing the liquid to be treated through the filter described above.

[0054] According to the removal method of this embodiment, metal ions (particularly Na ions, Fe ions, K ions, Ca ions, Co ions, Cr ions, Ni ions, etc.) can be efficiently removed, and a liquid with an extremely low metal ion content can be obtained (for example, a liquid in which the content of each metal ion is 500 ppt or less, more preferably 150 ppt or less, and even more preferably 100 ppt or less). Furthermore, according to the removal method of this embodiment, in addition to metal ions, halide ions (particularly Cl ions, Br ions, and I ions) can also be efficiently removed, and a liquid with an extremely low halide ion content can be obtained (for example, a liquid in which the content of each halide ion is 1 ppm or less, more preferably 0.1 ppm or less, and even more preferably 0.01 ppm or less).

[0055] In this embodiment, the content of metal ions in the liquid to be treated is not particularly limited. For example, the content of metal ions in the liquid to be treated may be 1 ppb or more, or may be 100 ppb or more. The upper limit of the content of metal ions in the liquid to be treated is not particularly limited, but may be, for example, 100 ppm or less, or 1000 ppb or less.

[0056] The liquid to be treated may be an aqueous solvent such as water, an organic solvent such as PGMEA, or a mixture thereof.

[0057] The conditions for passing the liquid to be treated are not particularly limited. For example, the space velocity (SV) is 6 to 200 h -1 The primary pressure may be, for example, 20 to 300 kPa.

[0058] The liquid to be treated may further contain an organic compound. That is, in this embodiment, metal ions can also be removed from a solution in which an organic compound is dissolved in a solvent. Also, in this embodiment, an additive can be added to the liquid to be treated and then the metal ions can be removed.

[0059] In this embodiment, the liquid to be treated may have passed through another filter. That is, the liquid passing step may include a first liquid passing step in which the liquid to be treated is passed through a first filter, and a second liquid passing step in which the liquid to be treated that has passed through the first liquid passing step is passed through a second filter. In this case, the above-mentioned filter is used as the second filter, and the first filter is not particularly limited.

[0060] In a preferred embodiment, the first filter may include a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder.

[0061] The first filter of this embodiment may be the same as the filter according to the above embodiment, except that the first filter is designed to filter water having an electrical resistivity of 18 MΩ·cm or more at a space velocity of 1200 h -1When the water is passed through the filter, the electrical resistivity of the water after passing through the filter does not need to be 13 MΩ·cm or more.

[0062] <Metal ion removal device> The metal ion removal device according to this embodiment includes a removal unit including the filter according to the above embodiment.

[0063] Fig. 1 is a diagram illustrating a preferred embodiment of a metal ion removal apparatus, and Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. The metal ion removal apparatus 100 shown in Fig. 1 comprises a removal section 10 including a filter 11 according to the above embodiment, a first tank 20 for storing a liquid to be treated 21, and a second tank 30 for storing a liquid 31 after metal ions have been removed. The interior of the removal section 10 is divided by the filter 11 into a first region 12 and a second region 13.

[0064] The first tank 20 and the removal unit 10 are connected by a first line L1, and the liquid to be treated 21 in the first tank 20 is sent to the first region 12 of the removal unit 10 through the first line L1. The liquid to be treated 21 sent to the first region 12 passes through a filter 11 and moves to the second region 13, at which time metal ions in the liquid to be treated 21 are removed by the filter 11. The second tank 30 and the removal unit 10 are connected by a second line L2, and the liquid to be treated (liquid 31) that has passed through the filter 11 is sent from the second region 13 to the second tank 30 through the second line L2.

[0065] Fig. 3 is a diagram illustrating another preferred embodiment of a metal ion removal apparatus. The metal ion removal apparatus 200 shown in Fig. 3 includes a first removal section 50 including a first filter 51, a second removal section 60 including a second filter 61, a first tank 70 for storing a liquid to be treated 71, a second tank 80 for storing an intermediate liquid 81 that has passed through the first filter 51, and a third tank 90 for storing a liquid 91 that has passed through the second filter 61 and from which metal ions have been removed. The second filter 61 is the filter according to the above embodiment.

[0066] The first tank 70 and the first removal unit 50 are connected by a first line L11, and the liquid to be treated 71 in the first tank 70 is sent to the first removal unit 50 through the first line L11. The liquid to be treated 71 sent to the first removal unit 50 is passed through the first filter 51. The first removal unit 50 is connected to the second tank 80 by a second line L12, and the intermediate liquid 81 that has passed through the first filter 51 is sent to the second tank 80 through the second line L12.

[0067] The second tank 80 and the second removal unit 60 are connected by a third line L13, and the intermediate liquid 81 in the second tank 80 is sent to the second removal unit 60 through the third line L13. The intermediate liquid 81 sent to the second removal unit 60 is passed through the second filter 61. The second removal unit 60 is connected to the third tank 90 by a fourth line L14, and the liquid 91, from which metal ions have been removed by passing through the second filter 61, is sent to the third tank 90 through the fourth line L14.

[0068] In a preferred embodiment, the first filter 51 may include a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder.

[0069] The first filter 51 of this embodiment may be the same as the filter according to the above embodiment. However, the first filter 51 is designed to filter water having an electrical resistivity of 18 MΩ·cm or more at a space velocity of 1200 h -1 When the water is passed through the filter, the electrical resistivity of the water after passing through the filter does not need to be 13 MΩ·cm or more.

[0070] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. [Example]

[0071] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0072] Example 1 <Activated carbon powder 1> Activated carbon powder was used, manufactured by Carbon Carbon Co., Ltd., under the trade name "ACTICARBONE ENO-PC" (BET specific surface area: 1400 m 2 / g, average particle size d2: 25 μm) was used.

[0073] <Thermoplastic resin powder 1> The thermoplastic resin powder was manufactured by Celanese (Oberhausen, Germany) under the trade name "GUR 2126" (ultra-high molecular weight polyethylene powder, weight-average molecular weight: approximately 4.5 × 10 6 g / mol, average particle size d1: 32 μm) was used.

[0074] <Preparation of filters> Activated carbon powder 1 (50 parts by mass) and thermoplastic resin powder 1 (50 parts by mass) were mixed, filled into a mold, and heated in an oven at 160°C for 10 minutes to produce a hollow cylindrical filter with an outer diameter of approximately 60 mm, an inner diameter of approximately 28 mm, and a length of approximately 250 mm. One of the openings of the produced filter was blocked to allow the liquid to flow from the outside to the inside of the filter. The produced filter was treated with a cleaning solution for more than 48 hours to obtain filter 1 of Example 1.

[0075] The resulting filter 1 was filled with water having an electrical resistivity of 18 MΩ·cm at a space velocity of 1200 h -1 After the water was passed through, the electrical resistivity of the water, as well as the chloride ion content and metal ion content, were measured. The results are shown in Table 1.

[0076] (Comparative Example 1) Filter 2 was prepared in the same manner as in Example 1, except that no treatment with a cleaning solution was carried out.

[0077] The resulting filter 2 was filled with water having an electrical resistivity of 18 MΩ·cm at a space velocity of 1200 h -1 After the water was passed through, the electrical resistivity of the water, as well as the chloride ion content and metal ion content, were measured. The results are shown in Table 1.

[0078] [Table 1] [Explanation of symbols]

[0079] 10...removal section, 11...filter, 20...first tank, 30...second tank, 100...metal ion removal device, 50...first removal section, 51...first filter, 60...second removal section, 61...second filter, 70...first tank, 80...second tank, 90...third tank, 200...metal ion removal device.

Claims

1. The porous molded body is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder, Water with an electrical resistivity of 18 MΩ cm or more is poured into a container at a space velocity of 1200 h －１ A filter having an electrical resistivity of 13 MΩ cm or more after passing water through the filter.

2. The average particle diameter d of the thermoplastic resin powder １ the average particle diameter d of the activated carbon powder ２ The ratio d ２ / d １ 2. The filter of claim 1, wherein the .gamma.

3. The average particle diameter d of the activated carbon powder ２ 3. The filter according to claim 1, wherein the particle size is 100 μm or less.

4. A method for removing metal ions from a liquid to be treated, comprising: A removal method comprising a liquid passing step of passing the liquid to be treated through the filter according to any one of claims 1 to 3.

5. The liquid passing step a first liquid passing step of passing the liquid to be treated through a first filter; a second liquid-passing step of passing the liquid to be treated that has been subjected to the first liquid-passing step through a second filter, The removal method according to claim 4, wherein the second filter is the filter according to any one of claims 1 to 3.

6. The removal method according to claim 5 , wherein the first filter includes a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder.

7. The first filter, a second filter for removing metal ions from the liquid to be treated that has passed through the first filter; Equipped with A metal ion removal device, wherein the second filter is the filter according to any one of claims 1 to 3.

8. 8. The metal ion removing device according to claim 7, wherein the first filter includes a porous molded body that is a sintered product of a mixed powder containing activated carbon powder and thermoplastic resin powder.

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