Filter and metal ion removal device

Abstract

To provide a filter which can efficiently remove metal ions in a processing liquid and can easily obtain a solution having an extremely low metal ion content. A depth filter including a porous molded article. The porous molded article is a sintered material of a mixed powder or a swollen material of the sintered material. The mixed powder contains a dry gel powder and a thermoplastic resin powder. The dry gel powder contains an ion exchange resin having a sulfonic acid group and a nitrogen-containing chelating resin.

Description

[0001] This patent application is a divisional application of the patent application with application number 2019800366907, application date May 29, 2019, and invention title "Filter and Metal Ion Removal Device". Technical Field

[0002] This disclosure relates to filters (purifiers) and metal ion removal devices. Background Technology

[0003] To date, there has been a need for solutions with low metal ion content as solutions for manufacturing electronic components such as integrated circuits. For example, Patent Document 1 describes a metal compound removal device that reduces the metal content in a surfactant to a level per ppb that allows its use in high-performance semiconductor materials.

[0004] Citation List

[0005] Patent Document 1 - JP 2005-213200 A Summary of the Invention

[0006] In recent years, electronic components have become increasingly complex. When wiring widths are narrowed due to such fine machining, even minute impurities can have adverse effects. For this reason, from a stability perspective, the permissible metal ion content of solutions used in the manufacture of electronic components has become increasingly lower. For example, it is expected that metal ions will be removed to levels even below ppb. However, achieving a complete reduction in metal ion content using conventional methods can be difficult. Furthermore, methods in related fields can involve numerous workflows and are therefore potentially inefficient.

[0007] In one aspect, this disclosure relates to providing a filter capable of effectively removing metal ions from a liquid being processed, and readily obtaining a solution with extremely low metal ion content. Furthermore, in another aspect, this disclosure relates to providing a metal ion removal apparatus using the aforementioned filter.

[0008] Solution to the problem

[0009] A first aspect of this disclosure relates to depth filters. The depth filter includes a porous molded article. The porous molded article is a sintered material of a mixed powder or a swollen material of a sintered material. The mixed powder comprises a dry gel powder and a thermoplastic resin powder. The dry gel powder comprises an ion exchange resin having sulfonic acid groups and a nitrogen-containing chelating resin.

[0010] Depth filters are formed using a dried gel powder containing ion exchange resin and nitrogen-containing chelating resin. Therefore, according to depth filters, metal ions can be effectively removed from the treated liquid.

[0011] In one respect, the ratio (C1 / C2) of the content of ion exchange resin C1 to the content of nitrogen-containing chelating resin C2 by mass can be between 0.1 and 100.

[0012] In one respect, when 100 parts by weight of a porous molded article is immersed in 500 parts by weight of propylene glycol 1-monomethyl ether 2-acetic acid at 23°C for 12 hours, the sulfate ion content in the immersion liquid may be 0.03 ppm or less.

[0013] In one aspect, when it has 18MΩ Water with a resistivity of cm or greater at 1200hr -1 When water passes through a depth filter at a spatial velocity, its resistivity can reach 15 MΩ after passing through the filter. cm or larger.

[0014] A second aspect of this disclosure relates to a metal ion removal apparatus. The metal ion removal apparatus includes a first filter and a second filter, the second filter being configured to remove metal ions from a processing liquid that has passed through the first filter. In the metal ion removal apparatus, the first filter may be a filter comprising a porous molded article. The porous molded article is a sintered material of mixed powder or a swollen material of sintered material. The mixed powder comprises a dried gel powder having a nitrogen-containing chelating resin and a thermoplastic resin powder. Furthermore, the second filter may be a depth filter according to the first aspect described above.

[0015] In one aspect, the first filter can be configured such that when it has 18MΩ Water with a resistivity of cm or greater at 1200hr -1 When the water passes through the first filter at a spatial velocity, the resistivity of the water after passing through the first filter is less than 15 MΩ. A filter with a diameter of cm.

[0016] A third aspect of this disclosure relates to a depth filter. The depth filter includes a porous molded article. The porous molded article is a sintered material of a mixed powder or a swollen material of a sintered material. The mixed powder comprises a dry gel powder and a thermoplastic resin powder, the dry gel powder comprising an ion exchange resin. In the depth filter, the number of powder particles P1 contained on a surface per unit area is less than the number of powder particles P2 contained on a cross-section per unit area. The surface is the surface of the porous molded article. The cross-section is the surface that divides the porous molded article into two parts along its thickness direction. Here, among the particles of the dry gel powder, P1 represents a powder particle whose projected area is 10 times or more than the average projected area of ​​the thermoplastic resin powder particles. The projected area of ​​the powder P1 particles is the area on the surface. P2 represents a powder particle whose projected area is 10 times or more than the average projected area of ​​the thermoplastic resin powder particles. The projected area of ​​the powder P2 particles is the area on the cross-section.

[0017] According to depth filters, dry gel powder, whose size is significantly different from that of thermoplastic resin powder, is more abundant inside the depth filter and less abundant on its surface. Therefore, according to depth filters, ion exchange resin is less likely to detach from the filter surface, thus making it easier to obtain a purer solution.

[0018] A fourth aspect of this disclosure relates to a depth filter. The depth filter includes a porous molded article. The porous molded article is a sintered material of a mixed powder or a swollen material of a sintered material. The mixed powder comprises a dry gel powder and a thermoplastic resin powder, the dry gel powder comprising an ion exchange resin. In the depth filter, the average particle size of the dry gel powder is two or more times the average particle size of the thermoplastic resin powder. Furthermore, according to the depth filter, when the surface of the porous molded article and each of the cross-sections dividing the porous molded article into two parts along the thickness direction are observed using a scanning electron microscope with a field of view of 950µm × 950µm, and the projected area of ​​five particles of the dry gel powder with a large projected area is subsequently calculated in each field of view, the average projected area on the surface is smaller than the average projected area on the cross-section.

[0019] According to depth filters, dry gel powder, whose size is significantly different from that of thermoplastic resin powder, is more abundant inside the depth filter and less abundant on its surface. Therefore, according to depth filters, ion exchange resin is less likely to detach from the filter surface, thus making it easier to obtain a purer solution.

[0020] In one aspect, the ion exchange resin may be an ion exchange resin containing sulfonic acid groups. The dried gel powder may also contain nitrogen-containing chelating resins.

[0021] In one respect, the ratio (C1 / C2) of the content of ion exchange resin C1 to the content of nitrogen-containing chelating resin C2 by mass can be between 0.1 and 100.

[0022] A fifth aspect of this disclosure relates to a metal ion removal apparatus. The metal ion removal apparatus includes a first filter and a second filter, the second filter being configured to remove metal ions from a processing liquid that has passed through the first filter. In the metal ion removal apparatus, the first filter may be a filter comprising a porous molded article. The porous molded article is a sintered material of mixed powder or a swollen material of sintered material. The mixed powder comprises a dry gel powder having a nitrogen-containing chelating resin and a thermoplastic resin powder. Furthermore, the second filter may be a depth filter according to the third or fourth aspect described above.

[0023] In one aspect, the first filter can be configured such that when it has 18MΩ Water with a resistivity of cm or greater at 1200hr -1 When the water passes through the first filter at a spatial velocity, the resistivity of the water after passing through the first filter is less than 15 MΩ. A filter with a diameter of cm.

[0024] According to this disclosure, a filter is provided that removes metal ions from a liquid being processed to easily obtain a solution with extremely low metal ion content. Furthermore, according to this disclosure, a metal ion removal apparatus using the aforementioned filter is provided. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating one embodiment of a metal ion removal device.

[0026] Figure 2 To show along Figure 1 A schematic diagram of the cross-sectional plane intercepted by line II-II.

[0027] Figure 3 This is a schematic diagram illustrating another embodiment of the metal ion removal device.

[0028] Figure 4(a) is an image of the outer surface of the porous molded article according to Example 1. Figure 4(b) is an image of the inner surface of the porous molded article according to Example 1. Figure 4(c) is an image of a cross-section of the porous molded article according to Example 1 divided into two parts along the thickness direction. Detailed Implementation

[0029] Preferred embodiments will now be described with reference to the accompanying drawings. It should be noted that, for better understanding, a portion of the drawings is shown in exaggerated form, and the size ratios, etc., are not limited to those shown in the drawings.

[0030] Filter

[0031] The filter according to this embodiment includes a porous molded article, which is a sintered material of mixed powder or a swollen material of sintered material. The mixed powder comprises dried gel powder and thermoplastic resin powder. The filter according to this embodiment is preferably used to remove metal ions from a processed liquid to obtain a solution with a low metal ion content. The filter according to this embodiment can be a depth filter.

[0032] Preferably, in the filter according to the embodiment, the dried gel powder comprises an ion exchange resin having sulfonic acid groups and a nitrogen-containing chelating resin. According to such a filter, metal ions in the treated liquid can be removed more effectively, and solutions with extremely low metal ion content can be readily obtained.

[0033] In this embodiment, the sintered material can have independent strength, and the dried gel powder can be fixed by thermoplastic resin powder. Furthermore, in this embodiment, since the dried gel powder is fixed by the thermoplastic resin powder in the sintered material, it maintains independent strength even when dimensional changes occur due to swelling of the dried gel powder. In other words, the porous molded article can have independent strength in either the sintered material or the swelling material of the sintered material.

[0034] For example, due to the water absorption rate of gel materials, the use of known adsorbent materials in gel materials causes significant dimensional changes and a reduction in strength. Therefore, gel materials have generally been held in place by a supporting medium or formed into a bead-like shape. In contrast, the filter according to this embodiment can be a filter that can be independent as described above. In this case, metal ions can be removed efficiently in a space-saving manner.

[0035] In this embodiment, only the dried gel powder needs to be a powder that absorbs water to swell and exhibits a gel-like form. For example, the dried gel powder can be obtained by drying hydrogel particles.

[0036] The dried gel powder includes an ion exchange resin. The ion exchange resin can be a resin containing ion exchange groups or chelating groups. It should be noted that an ion exchange resin containing chelating groups can also be described as a chelating resin. Examples of ion exchange groups include sulfonic acid groups, carboxylic acid groups, tertiary amino groups, and quaternary ammonium groups. Examples of tertiary amino groups include dialkylamino groups (groups represented by -NR12 (R1 each independently represents a substituted or unsubstituted alkyl group)). More specific examples of tertiary amino groups include dimethylamino groups and diethylamino groups. Furthermore, examples of quaternary ammonium groups include trialkylammonium groups (groups represented by -N+R23 (R2 each independently represents a substituted or unsubstituted alkyl group)). More specific examples of quaternary ammonium groups include trimethylammonium groups, dimethylammonium groups, and dimethylhydroxyethylammonium groups. Sulfonic acid groups are preferred as ion exchange groups. Examples of chelating groups include polyamines, aminophosphate groups, iminodiacetic acid groups, urea groups, thiols, and dithiocarbamate groups. Among them, chelating groups containing nitrogen atoms (such as polyamine, aminophosphate, iminodiacetic acid, urea, and dithiocarbamate groups) are preferred as chelating groups, and polyamine, aminophosphate, and iminodiacetic acid groups are more preferred.

[0037] Ion exchange resins can be resins such as polystyrene, acrylic resins, polyvinyl alcohol, cellulose, and polyamides. These resins can be modified to include the aforementioned ion exchange groups or chelating groups, or can be crosslinked with crosslinking agents such as divinylbenzene.

[0038] As described above, it is preferable that the dried gel powder comprises an ion exchange resin having sulfonic acid groups and a nitrogen-containing chelating resin. Here, it can also be stated that the nitrogen-containing chelating resin is an ion exchange resin containing chelating groups containing nitrogen atoms. In this case, the dried gel powder may be a powder comprising a first dried gel powder and a second dried gel powder, the first dried gel powder comprising an ion exchange resin having sulfonic acid groups and the second dried gel powder comprising a nitrogen-containing chelating resin. Furthermore, the dried gel powder may be a powder comprising a mixture of an ion exchange resin containing sulfonic acid groups and a nitrogen-containing chelating resin. According to this combination of ion exchange resin and nitrogen-containing chelating resin, even when the treated liquid contains multiple metal ions (e.g., iron and sodium ions), each metal ion can be significantly reduced. In other words, according to the above combination, metal ions in the treated liquid can be removed more effectively, and solutions with extremely low metal ion content can be easily obtained.

[0039] The ratio (C1 / C2) of the content of ion exchange resin containing sulfonic acid groups (C1) to the content of nitrogen-containing chelating resin (C2) by mass is preferably 0.1 or more, and more preferably 1 or more. This configuration allows for more significant removal of metal ions. Furthermore, the ratio (C1 / C2) by mass is preferably 100 or less, and more preferably 50 or less. This configuration significantly suppresses the elution of sulfate ions from the filter.

[0040] The dried gel powder may also contain inorganic materials. Examples of inorganic materials include silica gel, alumina gel, and chlorophyll. These inorganic materials can be modified to contain the aforementioned ion exchange groups or chelating groups.

[0041] The water absorption rate of the dried gel powder is preferably 30% by mass or higher, and more preferably 40% by mass or higher. With this structure, moisture can be effectively removed even when the liquid being processed contains trace amounts of water, and metal ions can be removed more effectively. Furthermore, the water absorption rate of the dried gel powder is preferably 90% by mass or lower, and more preferably 60% by mass or lower. With this structure, the strength of the porous molded article tends to be further enhanced.

[0042] It should be noted that in this specification, the water absorption rate of the dried gel powder is shown as a value calculated by the loss on drying method according to JIS K 7209:2000. More specifically, the weight (W1) of the swollen gel obtained by swelling the dried gel powder with sufficient water is measured. Subsequently, the swollen gel is dried in an oven (DRM620DB, manufactured by Advantec Toyo Kaisha, Ltd., Bunkyo-ku, Tokyo) at 105°C for 24 hours or longer, and the dry weight (W2) is measured. The water absorption rate is calculated based on the following formula (I).

[0043]

[0044] For example, the average particle size d1 of the dried gel powder may be 0.1 µm or larger, and preferably 1 µm or larger. Furthermore, for example, the average particle size d1 of the dried gel powder may be 500 µm or smaller, and preferably 200 µm or smaller.

[0045] For example, dried gel powder can be obtained by drying hydrogel particles. The drying method is not particularly limited. Examples of drying methods may include drying with hot air, stirring drying, and vacuum drying.

[0046] Preferably, the dried gel powder is a powder dried to a water content of 10% by mass or less. The water content of the dried gel powder is preferably 10% by mass or less, and more preferably 5% by mass or less.

[0047] It should be noted that in this specification, the water content of the dried gel powder is shown as a value measured by the loss on drying method. Specifically, the weight of the dried gel powder is measured (W3). Subsequently, the dried gel powder is dried in an oven (DRM620DB, manufactured by Advantech, Bunkyo-ku, Tokyo) at 105°C for 24 hours or longer, and the dry weight is measured (W4). The water absorption rate is calculated based on the following formula (II).

[0048]

[0049] In this embodiment, the thermoplastic resin powder is a powder made from a resin material containing thermoplastic resin as the main component. The particles of the thermoplastic resin powder are partially fused together by sintering, thereby forming a porous structure.

[0050] Based on the total mass of the thermoplastic resin powder, the content of 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.

[0051] Thermoplastic resin powders may also contain an additional component different from the thermoplastic resin. Examples of such additional components include plasticizers such as stearates, talc, silica, and antioxidants.

[0052] Preferably, the thermoplastic resin powder includes at least one type selected from the group consisting of ultra-high molecular weight polyethylene and polyamide as the thermoplastic resin.

[0053] As ultra-high molecular weight polyethylene (UHMWPE), UHMWPE having a weight-average molecular weight of 7.5 × 10⁵ g / mol or greater and 5 × 10⁷ g / mol or less is preferred, and UHMWPE having a weight-average molecular weight of 1.0 × 10⁶ g / mol or greater and 1.2 × 10⁷ g / mol or less is more preferred. It should be noted that the weight-average molecular weight of UHMWPE is shown as a value measured using the following method.

[0054] 1. "Standard Test Method for Dilute Solution Viscosity of Ethylene Polymers," D1601, Annual Book of ASTM Standards, American Society for Testing and Materials.

[0055] 2. "Standard Specification for Ultra-High-Molecular-Weight Polyethylene Molding and Extrusion Materials," D4020, Annual Book of ASTM Standards, American Society for Testing and Materials.

[0056] The melting point of ultra-high molecular weight polyethylene (UHMWPE) is not particularly limited. For example, the melting point of UHMWPE can be between 130°C and 135°C. Furthermore, the melt index of UHMWPE is preferably 1.0 g / 10 min (ASTM D1238 (ISO1133), 190°C, 21.6 kg load) or less, more preferably 0.5 g / 10 min or less.

[0057] As a polyamide, for example, fine particles of semi-crystalline polyamide with a melting point of 150°C or higher and 200°C or lower are preferred. Furthermore, polyamides with an average carbon number of 10 or more per monomer unit are preferred as such polyamides.

[0058] The average particle size of the thermoplastic resin powder is not particularly limited. For example, the average particle size of the thermoplastic resin powder may be 0.5 µm or larger, or 1 µm or larger. Furthermore, for example, the average particle size of the thermoplastic resin powder may be 500 µm or smaller, or 100 µm or smaller. There is a tendency to increase the average particle size of the thermoplastic resin powder to increase the porosity of porous molded articles, thereby enhancing liquid permeability. There is a tendency to decrease the average particle size of the thermoplastic resin powder to result in more dense porous molded articles, thereby increasing strength even further.

[0059] Preferably, the thermoplastic resin powder is a non-spherical resin powder. For example, the thermoplastic resin powder may have a shape in which microspheres agglomerate into a bunch of grapes, or it may have a "konpeito"-like shape in which multiple protrusions are formed on the spherical particles. According to the non-spherical thermoplastic resin powder, the tolerance to dimensional changes during swelling tends to be enhanced or even more.

[0060] Preferably, the thermoplastic resin powder is a porous powder. For example, the bulk density of the porous thermoplastic resin powder can be from 0.1 g / cm³ to 0.7 g / cm³, or from 0.2 g / cm³ to 0.6 g / cm³. It should be noted that in this specification, the bulk density of the porous thermoplastic resin powder is shown as a value measured according to the method of ISO 60.

[0061] In this embodiment, the ratio d2 / d1 of the average particle size d2 of the dried gel powder to the average particle size d1 of the thermoplastic resin powder is preferably 1.3 or more. Furthermore, the ratio (d3 - d2) / d1 of the difference between the average particle size d2 of the dried gel powder and the average particle size d3 of the dried gel powder upon swelling by water absorption to the average particle size d1 of the thermoplastic resin powder is preferably 4.0 or less. With this configuration, the strength of the porous molded article is further enhanced, and therefore the porous molded article can more preferably be used as a filter capable of operating independently.

[0062] The average particle size d1 of the thermoplastic resin powder represents the value of D50, which was calculated using laser diffraction and scattering methods according to JIS Z 8825:2013. More specifically, the particle size distribution of the thermoplastic resin powder was calculated using laser diffraction and scattering methods with a Mastersizer 3000 available from Malvern Panalytical Ltd, Worcestershire, United Kingdom. The particle size was integraled in ascending order from the particle size with the smallest number of particles among all particle sizes. The D50 corresponding to 50% was then used as the average particle size d1.

[0063] When swollen with water absorption, the average particle size d3 of the dry gel powder indicates the average particle size of the swollen gel obtained by swelling the dry gel powder with sufficient water. In this embodiment, the average particle size d3 of the swollen gel is represented by the value of D50, which is calculated using laser diffraction and scattering methods according to JIS Z 8825:2013. More specifically, the particle size distribution of the swollen gel is calculated using laser diffraction and scattering methods using a Mastersizer 3000 available from Malvern Panaco Ltd., Worcestershire, UK. The particle size is integraled in ascending order from the particle size with the smallest number of particles among all particle sizes. The D50 corresponding to 50% is then used as the average particle size d3.

[0064] In this embodiment, the average particle size d2 of the dried gel powder represents the average particle size d3 of the swollen gel and the linear expansion coefficient α due to water absorption by the dried gel powder, calculated based on the following formula (III).

[0065]

[0066] In this embodiment, the linear expansion coefficient α caused by the water absorption of the dry gel powder is shown as a value calculated by the following method. First, based on the apparent density measured using the method according to JIS K 7365:1999, the volume (V1) of the dry gel powder obtained by swelling the dry gel powder with sufficient water and the volume (V2) of the swollen gel are calculated. The linear expansion coefficient α can then be obtained using these volumes V1 and V2 based on the following formula (IV).

[0067]

[0068] The ratio d2 / d1 of the average particle size d2 of the dried gel powder to the average particle size d1 of the thermoplastic resin powder is preferably 1.3 or more, and more preferably 2 or more. Furthermore, the ratio d2 / d1 is preferably 50 or less, and more preferably 25 or less. This structure prevents the porous molded article from becoming brittle due to dimensional changes caused by swelling, and therefore makes it easier to obtain filters with higher strength.

[0069] The ratio (d3-d2) / d1 of the difference between the average particle size d2 of the dried gel powder and the average particle size d3 of the dried gel powder after swelling by water absorption, and the average particle size d1 of the thermoplastic resin powder, is 4.0 or less, preferably 3.0 or less. Furthermore, the ratio (d3-d2) / d1 is preferably 0.2 or more, and more preferably 0.3 or more. With this structure, porous molded articles can be prevented from becoming brittle due to dimensional changes caused by swelling, and thus filters with higher strength can be obtained more easily.

[0070] In this embodiment, the porous molded article is formed by sintering a mixed powder comprising dried gel powder and thermoplastic resin powder.

[0071] In one aspect, a porous molded article can be described as a molded article formed in such a way that particles of dried gel powder are dispersed and fixed in a porous structure formed by sintering thermoplastic resin powder. Furthermore, a porous molded article can also be described as a molded article formed in such a way that particles of dried gel powder are bonded together by thermoplastic resin powder.

[0072] The content of dry gel powder in the mixed powder is preferably 10 parts by weight or more, and more preferably 25 parts by weight or more, relative to 100 parts by weight of thermoplastic resin powder. Furthermore, the content of dry gel powder in the mixed powder is preferably 900 parts by weight or less, and more preferably 300 parts by weight or less, relative to 100 parts by weight of thermoplastic resin powder.

[0073] The mixed powder may also contain components other than the dried gel powder and thermoplastic resin powder as additives. For example, the mixed powder may also contain activated carbon, media for reducing heavy metals, media for removing arsenic, antimicrobial media, ion exchange media, iodide, resin, fiber, gas absorption media, etc. Based on the total mass of the mixed powder, the content of such additives is preferably 20% by mass or less, and more preferably 5% by mass or less.

[0074] In this embodiment, the mixed powder is loaded into a mold or the like according to the desired shape of the porous molded article, and then sintered. The sintering of the mixed powder can be carried out under conditions that fuse the thermoplastic resin powder.

[0075] For example, the sintering temperature can be set to be equal to or higher than the melting point of the thermoplastic resin in the thermoplastic resin powder. For example, the sintering temperature can be 140°C or higher, and preferably 150°C or higher. In addition, for example, the sintering temperature can be 200°C or lower, or 180°C or lower.

[0076] There are no particular restrictions on the sintering time. For example, the sintering time can be set from 5 minutes to 120 minutes, and from 10 minutes to 60 minutes.

[0077] By appropriately selecting the mold into which the mixed powder is loaded during sintering, porous molded articles can be formed into various shapes. For example, porous molded articles can be formed into various shapes, such as disc-shaped, hollow cylindrical, bell-shaped, conical, and hollow star-shaped.

[0078] For example, the thickness of a porous molded article may be 0.2 mm or greater, and preferably 1 mm or greater, and more preferably 5 mm or greater. Furthermore, for example, the thickness of a porous molded article may be 1000 mm or less, and preferably 100 mm or less.

[0079] The porous molded article can be a sintered material of mixed powders, or it can be a swollen material made by swelling the sintered material. For example, the sintered material can be swollen with a solvent. Examples of solvents include water and organic solvents. In this embodiment, organic solvents are preferred as polar solvents that cause the sintered material to swell, and, for example, propylene glycol 1-monomethyl ether 2-acetic acid (PGMEA), propylene glycol monomethyl ether (PGME), cyclohexane, and ethyl lactate are particularly preferred.

[0080] The filter according to the embodiment includes the aforementioned porous molded article. The filter according to this embodiment can be a filter formed from a porous molded article, or it may also include another component, as long as the filter can completely remove metal ions.

[0081] The shape of the filter according to this embodiment is not particularly limited. For example, the shape of the filter according to this embodiment can be such as a cylindrical shape, a prism shape, a plate shape, a bell shape, a spherical shape, a hemispherical shape, and a cube shape, and these shapes can be hollow.

[0082] In this embodiment, the dried gel powder can be a powder with particles larger than the thermoplastic resin powder particles. Specifically, for example, the average particle size of the dried gel powder can be larger than the average particle size of the thermoplastic resin powder, and can be two or more times the average particle size of the thermoplastic resin powder.

[0083] Here, among the particles of the dried gel powder, P1 represents a powder particle whose projected area is 10 times or more than the average projected area of ​​the thermoplastic resin powder particles. The projected area of ​​powder P1 particles is the area on the surface (at least one surface, preferably two surfaces) of the porous molded article. Furthermore, P2 represents a powder particle whose projected area is 10 times or more than the average projected area of ​​the thermoplastic resin powder particles. The projected area of ​​powder P2 particles is the area on the cross-section dividing the porous molded article into two parts along the thickness direction. In this case, it is preferable that the number of powder P1 particles per unit area of ​​surface is less than the number of powder P2 particles per unit area of ​​cross-section. In this case, it can be said that dried gel powder, whose size is significantly different from that of the thermoplastic resin powder, is more abundant within the depth filter and less abundant on the surface of the depth filter. According to such a depth filter, the ion exchange resin is less likely to detach from the filter surface, thus making it easier to obtain a purer solution.

[0084] It should be noted that the average projected area of ​​the thermoplastic resin powder described above is a value calculated from the average particle size of the thermoplastic resin powder. Specifically, the area of ​​a circle with a diameter equal to the average particle size of the thermoplastic resin powder is calculated, and this area is used as the average projected area of ​​the thermoplastic resin powder.

[0085] Furthermore, for example, the projected area of ​​thermoplastic resin powder on the surface of a porous molded article and on a cross section that divides the porous molded article into two parts along the thickness direction can be calculated from the observation image observed using a scanning electron microscope.

[0086] Here, the surface of the porous molded article and each of the cross-sections dividing the porous molded article into two parts along the thickness direction are observed using a scanning electron microscope with a field of view of 950µm × 950µm. Subsequently, five particles from the dried gel powder are selected in descending order from the particles with the largest projected area in each field of view. In this case, it is preferable that the average projected area of ​​the five particles of dried gel powder on the surface is less than the average projected area of ​​the five particles of dried gel powder on the cross-section. In this case, it can be said that larger particles of dried gel powder are more present within the depth filter and less present on the surface of the depth filter. According to such a depth filter, the detachment of ion exchange resin from the filter surface is less likely to occur, thus making it easier to obtain a purer solution.

[0087] Regarding the filter according to the implementation scheme, when it has 18MΩ Water with a resistivity of cm or greater at 1200hr -1 When the water passes through the filter according to the embodiment, it is preferable that the resistivity of the water is 15 MΩ after passing through the filter. cm or larger. Note that it is only necessary to ensure the water has an Ω₁₀ of 18 MΩ before passing through the filter. A resistivity of cm or greater is achieved, allowing the water to have a resistivity of approximately 18.23 MΩ before passing through the filter. The theoretical limit for resistivity is cm. Furthermore, after water is passed through the filter, there is no particular upper limit on the resistivity of the water. For example, the upper limit may be equal to or less than the resistivity before the water is passed through the filter. With such filters, metal ions in the treated liquid can be removed more significantly, and solutions with even lower metal ion content can be easily obtained.

[0088] It should be noted that in this instruction manual, the resistivity of water is shown as the value measured using the ERF-001-CT embedded resistivity sensor available from HORIBA, Ltd.

[0089] The method for obtaining such a filter is not particularly limited. Examples of methods for obtaining such a filter include a method of cleaning the porous molded article by flowing a cleaning liquid through it. As the cleaning liquid, examples include water, organic solvents, acidic solutions, alkaline solutions, and mixtures thereof. The cleaning conditions are not particularly limited. For example, the flow rate during cleaning can be from 10 mL / min to 10 L / min, and the space velocity during cleaning can be 6 hours. -1 Up to 6000hr -1 Furthermore, for example, the temperature of the cleaning liquid during cleaning can range from 1°C to 99°C.

[0090] In this embodiment, when 100 parts by weight of a porous molded article is immersed in 500 parts by weight of propylene glycol 1-monomethyl ether 2-acetic acid (PGMEA) at 23°C for 12 hours, it is preferred that the sulfate ion content in the immersion liquid is 0.03 ppm or less. It should be noted that the sulfate ion content in the PGMEA is set to 0.003 ppm or less before immersion. Furthermore, the lower limit of the sulfate ion content in the immersion liquid is not particularly limited. For example, the lower limit of the sulfate ion content in the immersion liquid may be the detectable limit or less.

[0091] Note that in this specification, the sulfate ion content in PGMEA is shown as the value measured using an ion chromatograph (DIONEX ICS-2100) available from Thermo Fisher Scientific KK.

[0092] There are no particular limitations on the methods for obtaining such filters. Examples of methods for obtaining such filters include using a dry gel powder containing an ion exchange resin and a nitrogen-containing chelating resin.

[0093] Methods for removing metal ions

[0094] The metal ion removal method according to the embodiment is a method for removing metal ions from a treatment liquid, and includes a liquid passage step of passing the treatment liquid through the aforementioned filter.

[0095] According to the removal method of this embodiment, metal ions (specifically, such as Na ions, Fe ions, K ions, Ca ions, Co ions, Cr ions and Ni ions) can be effectively removed, and thus a liquid with extremely low metal ion content can be obtained (e.g., a liquid with a content of 500 ppt or less for each type of metal ion, more preferably 150 ppt or less, and even more preferably 100 ppt or less).

[0096] In this embodiment, the content of metal ions in the treated liquid is not particularly limited. For example, the content of metal ions in the treated liquid may be 1 ppb or more, or 100 ppb or more. The upper limit of the content of metal ions in the treated liquid is not particularly limited. For example, the upper limit of the content of metal ions in the treated liquid may be 100 ppm or less, or 1000 ppb or less.

[0097] The liquid being processed can be a water-based solvent (such as water), an organic solvent (such as PGMEA), or a mixture thereof.

[0098] This allows for unrestricted conditions when processing liquids through the filter. For example, the space velocity (SV) can be 6 hours. -1 Up to 200hr -1In addition, for example, the main pressure can be from 20 kPa to 300 kPa.

[0099] The treatment liquid may also contain organic compounds. In other words, in this embodiment, metal ions can also be removed from a solution obtained by dissolving organic compounds in a solvent. Furthermore, in this embodiment, metal ions can also be removed after additives are added to the treatment liquid.

[0100] In a preferred aspect, the removal method described above may be a method for removing metal ions from a treatment liquid containing compounds comprising acidic groups. In this case, the removal method may be a method comprising an addition step of adding a strong alkali to the treatment liquid, and a liquid-passing step of causing the treatment liquid with the added strong alkali to pass through a filter according to the above embodiment.

[0101] In the above respects, by adding a step, metal ions can be removed more significantly from the processing liquid containing compounds with acidic groups.

[0102] Compounds containing acidic groups can be low-molecular-weight or high-molecular-weight compounds. Examples of acidic groups include phenolic hydroxyl groups, carboxyl groups, sulfone groups, and nitrate groups. Among these, phenolic hydroxyl groups are preferred from the viewpoint that they more significantly produce the effect achieved by the addition step.

[0103] For example, compounds containing acidic groups may include at least one type selected from the group consisting of phenolic resins, acrylic resins, epoxy resins, silicone resins, and monomers that are raw materials for these resins. Furthermore, from the viewpoint that compounds containing acidic groups more significantly produce the effects achieved by the addition step, it is preferable that compounds containing acidic groups include phenolic resins.

[0104] There are no particular restrictions on the strong bases used in the addition step. Examples of strong bases include metal hydroxides such as sodium hydroxide and tetraalkylammonium hydroxides such as tetramethylammonium hydroxide.

[0105] The preferred equivalence ratio of strong base to acidic groups in the treated liquid is 1.0 × 10⁻⁶. -9 Or higher, and more preferably 1.0 × 10 -8 Or higher. Furthermore, the aforementioned equivalent ratio is preferably 1.0 × 10⁻⁶. -4 Or lower, and more preferably 1.0 × 10 -5 Or even lower. Using this structure, metal ions are removed more significantly during the liquid pass-through process.

[0106] In this embodiment, the liquid to be processed may be liquid that has already passed through another filter. In other words, the liquid passing step may include a first liquid passing step that passes the liquid to be processed through a first filter and a second liquid passing step that passes the liquid that has already undergone the first liquid passing step through a second filter. In this case, the aforementioned filter is used as the second filter, and the first filter is not particularly limited.

[0107] In a preferred aspect, the first filter described above may be a filter comprising a porous molded article, which is a sintered material of a mixed powder or a swollen material of a sintered material. The mixed powder comprises a dry gel powder and a thermoplastic resin powder, the dry gel powder comprising an ion exchange resin.

[0108] As an exemplary example of the first filter in this regard, a filter similar to the filter according to the above embodiment can be given. It should be noted that, regarding the first filter, when it has 18MΩ... The resistivity of water at 1200 hr cm -1 When the water passes through the first filter at a spatial velocity, the resistivity of the water does not need to be 15 MΩ after the water passes through the first filter. cm or larger.

[0109] In this respect, it is preferred that the second filter (i.e., the filter according to the above embodiment) is a filter containing an ion exchange resin comprising sulfonic acid groups and a nitrogen-containing chelating resin as its dried gel powder. Furthermore, it is preferred that the ion exchange resin of the first filter comprises at least one type of group selected from the group consisting of aminophosphate groups, iminodiacetic acid groups, and tertiary amino groups. According to this combination of the first and second filters, even when the treated liquid contains multiple metal ions (e.g., iron and sodium ions), each metal ion can be significantly reduced.

[0110] Metal ion removal device

[0111] The metal ion removal device according to this embodiment includes a removal unit, which includes a filter according to the above embodiment.

[0112] Figure 1 This is a schematic diagram illustrating a preferred mode of a metal ion removal device. Figure 2 To show along Figure 1 A schematic diagram of the cross-section taken by line II-II. Figure 1The metal ion removal device 100 shown includes a removal unit 10, which includes a filter 11 according to the above embodiment, a first tank 20 for storing processed liquid 21, and a second tank 30 for storing liquid 31 after metal ion removal. Furthermore, the interior of the removal unit 10 is divided into a first region 12 and a second region 13 by the filter 11.

[0113] The first tank 20 and the removal unit 10 are connected to the first pipeline L1. The processing liquid 21 in the first tank 20 is supplied to the first region 12 of the removal unit 10 via the first pipeline L1. The processing liquid 21 supplied to the first region 12 passes through the filter 11 to be transferred to the second region 13. At this time, metal ions in the processing liquid 21 are removed by the filter 11. The second tank 30 and the removal unit 10 are connected to the second pipeline L2. The processing liquid (liquid 31) passing through the filter 11 passes through the second pipeline L2, so that the processing liquid (liquid 31) is supplied from the second region 13 to the second tank 30.

[0114] Figure 3 This is a schematic diagram illustrating another preferred mode of a metal ion removal device. Figure 3 The metal ion removal device 200 shown includes a first removal unit 50, which includes a first filter 51; a second removal unit 60, which includes a second filter 61; a first tank 70, which stores a processed liquid 71; a second tank 80, which stores an intermediate liquid 81 that has passed through the first filter 51; and a third tank 90, which stores a liquid 91 that has passed through the second filter 61 to remove its metal ions. The second filter 61 is a filter according to the above embodiment.

[0115] The first tank 70 and the first removal unit 50 are connected to the first pipeline L11. The processed liquid 71 in the first tank 70 is supplied to the first removal unit 50 via the first pipeline L11. The processed liquid 71 supplied to the first removal unit 50 is then passed through the first filter 51. The first removal unit 50 is connected to the second tank 80 via the second pipeline L12. The intermediate liquid 81 that has passed through the first filter 51 is supplied to the second tank 80 via the second pipeline L12.

[0116] The second tank 80 and the second removal unit 60 are connected to the third pipeline L13. The intermediate liquid 81 in the second tank 80 is supplied to the second removal unit 60 via the third pipeline L13. The intermediate liquid 81 supplied to the second removal unit 60 is then passed through the second filter 61. The second removal unit 60 is connected to the third tank 90 via the fourth pipeline L14. The liquid 91, having passed through the second filter 61 to remove its metal ions, is supplied to the third tank 90 via the fourth pipeline L14.

[0117] According to this embodiment, the first filter 51 is a filter comprising a porous molded article, which is a sintered material of mixed powder or a swollen material of sintered material. The mixed powder comprises a dry gel powder having a nitrogen-containing chelating resin and a thermoplastic resin powder. In this case, the second filter 61 is the aforementioned filter.

[0118] In this embodiment, regarding the first filter 51, when it has 18MΩ Water with a resistivity of cm or greater at 1200hr -1 When the water passes through the first filter 51 at a spatial velocity, the resistivity of the water after passing through the first filter 51 can be less than 15 MΩ. cm.

[0119] In this respect, it is preferred that the second filter 61 (i.e., the filter according to the above embodiment) is a filter containing an ion exchange resin comprising sulfonic acid groups and a nitrogen-containing chelating resin as its dried gel powder. Furthermore, it is preferred that the ion exchange resin of the first filter 51 comprises at least one type of group selected from the group consisting of aminophosphate groups, iminodiacetic acid groups, and tertiary amino groups. According to this combination of the first filter 51 and the second filter 61, even when the treated liquid contains multiple metal ions (e.g., iron ions and sodium ions), each metal ion can be significantly reduced.

[0120] Preferred embodiments are described above. However, this disclosure is not limited to the embodiments described above.

[0121] Example

[0122] The present disclosure will now be described in further detail with reference to embodiments. However, the present disclosure is not limited to these embodiments.

[0123] Example 1

[0124] dry gel Powder A-1

[0125] 25 parts by weight of strongly acidic cation exchange resin particles containing sulfonic acid groups and 5 parts by weight of chelating resin particles containing aminophosphate groups were mixed together. The mixture was dried in an oven (DRM620DB, available from Advantech, Bunkyo Ward, Tokyo) at 110°C for 36 hours or longer. This yielded a dried gel powder with an average particle size of 440 µm. Subsequently, the dried gel powder was milled to prepare a dried gel powder A-1 with an average particle size d2 of 90 µm.

[0126] Thermoplastic resin powder A-1

[0127] The thermoplastic resin powder used is "GUR 2126" (ultra-high molecular weight polyethylene powder, weight average molecular weight: approximately 4.5 × 10⁶ g / mol, average particle size d1: 32 µm), available from Celanese Corporation (Oberhausen, Germany). Specifically, d2 is two or more times that of d1.

[0128] Manufacturing of Filter A-1

[0129] Dry gel powder A-1 (30 parts by weight) and thermoplastic resin powder A-1 (70 parts by weight) are mixed together. The mixture is loaded into a mold and then heated in an oven at 160°C for 10 minutes. This produces a hollow cylindrical filter with an outer diameter of approximately 60 mm, an inner diameter of approximately 28 mm, and a length of approximately 50 mm. The opening on one side of the manufactured filter is closed, allowing the processing liquid to flow from the outside into the interior of the filter. The manufactured filter is treated with a cleaning solution for 72 hours or longer. This yields filter A-1.

[0130] Make it have 18MΩ The resistivity of water at 1200 hr cm -1 The spatial velocity is obtained through filter A-1. In this case, after the water passes through filter A-1, the resistivity of the water is 18 MΩ. cm. Furthermore, the obtained filter A-1 was immersed in PGMEA at room temperature (23°C) for 12 hours in a solution five times the mass of filter A-1 (mass ratio), and the sulfate ion content in the impregnation liquid was measured. In this case, the sulfate ion content in the impregnation liquid was less than 0.003 ppm.

[0131] Furthermore, the dried gel powder on the surface and cross-section of the resulting filter A-1 was observed. Specifically, filter A-1 was frozen with liquid nitrogen and then cut with a knife, dividing it into two parts along its thickness direction. This prepared the sample to be measured. Surface observation of each of the outer, inner, and cross-sections of filter A-1 was performed using scanning electron microscopy (SEM) (magnification: 100x). Additionally, sulfur distribution was analyzed using energy-dispersive X-ray spectroscopy (EDX). The location of the ion exchange resin was determined by the analysis to identify the dried gel powder. Next, within a freely selectable field of view of 950µm × 950µm, five particles of dried gel powder were selected in descending order from the largest particles (note that particles partially cut out from the field of view were excluded). The projected area of ​​each of the five selected particles of powder was measured, and the average projected area was calculated. Table 1 shows the results. As shown in Table 1, the average value of each of the two surfaces (outer and inner surfaces) is less than the average value of the cross-section (equal to or less than 2 / 3 of its value).

[0132] Figure 4(a) shows the SEM image and EDX analysis results of the outer surface of filter A-1. Figure 4(b) shows the SEM image and EDX analysis results of the inner surface of filter A-1. Figure 4(c) shows the SEM image and EDX analysis results of the cross-section of filter A-1.

[0133] Table 1

[0134] In Example 1, since the average particle size of the thermoplastic resin powder is 32 µm, the average projected area of ​​the thermoplastic resin powder can be assumed to be 803 µm². The number of particles contained in the dried gel powder with a projected area 10 times or more than the average projected area of ​​the thermoplastic resin powder (8030 µm² or greater) was calculated from SEM images of the outer surface, inner surface, and cross-section of filter A-1. In this case, it was confirmed that the number of particles contained on each of the outer and inner surfaces was less than the number of particles contained on the cross-section.

[0135] Comparative Example 1

[0136] Dry gel powder B-1

[0137] Strongly acidic cation exchange resin particles containing sulfonic acid groups were dried in an oven (DRM620DB, available from Advantech, Bunkyo Ward, Tokyo) at 110°C for 36 hours or longer. This yielded a dried gel powder with an average particle size of 440 µm. Subsequently, the dried gel powder was milled to prepare dried gel powder B-1 with an average particle size d2 of 90 µm.

[0138] Manufacturing of filter B-1

[0139] 50 parts by weight of dried gel powder B-1 and 50 parts by weight of thermoplastic resin powder A-1 are mixed together. The mixture is loaded into a mold and then heated in an oven at 160°C for 10 minutes. This produces 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. The opening on one side of the manufactured filter is closed, allowing the processing liquid to flow from the outside into the interior of the filter. The manufactured filter is treated with a cleaning solution for 48 hours or longer. This yields filter B-1.

[0140] Make it have 18MΩ The resistivity of water at 1200 hr cm -1 The spatial velocity is obtained by passing the water through filter B-1. In this case, after passing the water through filter B-1, the resistivity of the water is 17.6 MΩ. cm. Furthermore, the obtained filter B-1 was immersed in PGMEA at room temperature (23°C) for 12 hours, and the sulfate ion content in the impregnation liquid was measured. In this case, the sulfate ion content in the impregnation liquid was 0.64 ppm.

[0141] Flow test 1 (flow test of solutions containing phenolic resin)

[0142] Under conditions of a main-side pressure of 50 kPa and a flow rate of 100 ml / min, a PGMEA solution containing 5% by mass of phenolic resin (SP1006N, available from Asahi Yukizaai Corporation) was passed through the filters obtained in Example 1 and Comparative Example 1 above. The iron ion content in the solution was measured before and after passing iron ions through the filters. Table 2 shows the results.

[0143] Example 2

[0144] dry gel Powder A-2

[0145] The chelated resin particles containing aminophosphate groups were dried in an oven (DRM620DB, available from Advantech, Bunkyo Ward, Tokyo) at 110°C for 36 hours or longer. This yielded a dried gel powder with an average particle size of 440 µm. Subsequently, the dried gel powder was ground to prepare a dried gel powder A-2 with an average particle size d2 of 90 µm.

[0146] First Filter Manufacturing

[0147] Dry gel powder A-2 (40 parts by weight) and thermoplastic resin powder A-1 (60 parts by weight) were mixed together. The mixture was loaded into a mold and then heated in an oven at 160°C for 10 minutes. This produced a disc-shaped filter with a diameter of approximately 47 mm and a thickness of approximately 5 mm. The manufactured filter was designed so that the treatment liquid flowed through the filter from top to bottom. A first filter was obtained without treating the manufactured filter with a cleaning liquid.

[0148] Make it have 18MΩ The resistivity of water at 1200 hr cm -1 The water's spatial velocity passes through the first filter. In this case, after passing the water through the first filter, the water's resistivity is 0.4 MΩ. cm.

[0149] second Filter Manufacturing

[0150] Similar to filter A-1, a second filter is obtained.

[0151] Make it have 18MΩ The resistivity of water at 1200 hr cm -1 The spatial velocity is obtained by passing the water through the second filter. In this case, after passing the water through the second filter, the water's resistivity is 18 MΩ. cm. Furthermore, the obtained second filter was immersed in PGMEA at room temperature (23°C) for 12 hours, and the sulfate ion content in the impregnation liquid was measured. In this case, the sulfate ion content in the impregnation liquid was less than 0.003 ppm.

[0152] Manufacturing of metal ion removal devices

[0153] The first filter and the second filter are connected such that the liquid to be processed flows through the first filter and the second filter in this order. In this way, a metal ion removal device is manufactured.

[0154] Flow test 2 (flow test of solutions containing phenolic resin)

[0155] A PGMEA solution containing 5% by mass of phenolic resin (SP1006N, manufactured by Asahi Chemicals) was provided to the metal ion removal device obtained in Example 2 above, and the PGMEA solution was passed through a first filter and a second filter. The iron ion content in the solution was measured before and after passing iron ions through the filters. Table 2 shows the results.

[0156] Table 2

[0157] refer to mark List

[0158] 10: Removal unit, 11: Filter, 20: First tank, 30: Second tank, 100: Metal ion removal device, 50: First removal unit, 51: First filter, 60: Second removal unit, 61: Second filter, 70: First tank, 80: Second tank, 90: Third tank, 200: Metal ion removal device.

Claims

1. A depth filter comprising a porous molded article, said porous molded article being a sintered material of mixed powders or a swollen material thereof. The mixed powder comprises a dry gel powder and a thermoplastic resin powder, wherein the dry gel powder comprises: Ion exchange resins containing sulfonic acid groups; and Nitrogen-containing chelating resins, The mass ratio (C1 / C2) of the ion exchange resin to the nitrogen-containing chelating resin is from 0.1 to 100. The average particle size of the dried gel powder is at least twice the average particle size of the thermoplastic resin powder, and in, Based on scanning electron microscopy observations with a field of view of 950 μm × 950 μm, the average projected area of ​​the dried gel particles with a larger projected area on the surface of the porous molded article is smaller than the average projected area on the cross section of the porous molded article along the thickness direction.

2. A metal ion removal device, comprising: First filter; and A second filter, configured to remove metal ions from the liquid that has passed through the first filter. The first filter comprises a porous molded article, the porous molded article comprising dried gel powder and thermoplastic resin powder, the dried gel powder comprising a nitrogen-containing chelating resin. The second filter is the depth filter according to claim 1. Furthermore, the first filter is configured such that when water with a resistivity of ≥18 MΩ·cm is subjected to a flow rate of 1200 h⁻¹, -1 When the space velocity passes through the first filter, the specific resistance after passing through is <15 MΩ·cm.

3. The depth filter according to claim 1, wherein: When water with a resistivity ≥18 MΩ·cm is subjected to a flow rate of 1200 h⁻¹ -1 When the space velocity passes through the filter, the specific resistance after passing through is ≥15 MΩ·cm.

4. The depth filter according to claim 1, wherein: When water with a resistivity ≥18 MΩ·cm is subjected to a flow rate of 1200 h⁻¹ -1 When the space velocity passes through the filter, the specific resistance after passing through is <15 MΩ·cm.

5. The depth filter according to claim 1, wherein the mass ratio (C1 / C2) is 0.5 to 50.

6. The depth filter according to claim 1, wherein the ion exchange resin is a strongly acidic cation exchange resin.

7. The metal ion removal device according to claim 2, wherein the second filter is configured such that when water having a resistivity of ≥18 MΩ·cm is subjected to a flow rate of 1200 h⁻¹, -1 When the space velocity passes through the second filter, the specific resistance after passing through is ≥15 MΩ·cm.

8. The metal ion removal device according to claim 2, wherein: The number of dried gel powder particles with a projected area ≥ 10 times the projected area of ​​the thermoplastic resin powder on the surface of the porous molded article is less than the number on the cross-section per unit area.

9. The metal ion removal device according to claim 2, wherein the first filter and the second filter are arranged in series along the flow direction of the liquid.

10. The metal ion removal apparatus according to claim 2, wherein the thermoplastic resin powder comprises a polyolefin resin.

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