JP6657184B2 - Chemical filter - Google Patents

Description

  The present invention relates to a chemical filter for removing a siloxane compound from a fluid (particularly, from air). The present invention also relates to a method for purifying fluid using the chemical filter and a gas sensor provided with the chemical filter.

  In a living environment, a siloxane compound exists in every environment. For example, siloxane compounds are used for all substances existing in the living environment, such as packing parts and sealing materials existing in buildings such as ordinary homes and clean rooms, adhesives used in construction sites, shampoos, cosmetics, and the like. ing.

  It is known that a disilazane compound such as hexamethyldisilazane (HMDS) is used as a photoresist adhesive in an exposure step of a semiconductor manufacturing process. HMDS, for example, is sprayed as a gas on the wafer surface, thereby replacing the hydroxyl group on the wafer surface with a trimethylsilanol group, thereby rendering the wafer surface hydrophobic and improving the adhesion of the wafer surface to the resist agent. . However, when the siloxane compound is present in the air, if the siloxane compound adheres to the surface of the wafer, the characteristics of the semiconductor are changed, and even at a low concentration, the product yield may be reduced.

  To remove the siloxane compound, a chemical filter using activated carbon as an adsorbent is usually used. As an adsorbent using activated carbon, for example, an activated carbon for siloxane removal having two types of activated carbons having different average pore diameters is known (see Patent Document 1).

  In addition to activated carbon, resins or porous materials into which acidic functional groups such as sulfonic acid groups have been introduced are used as adsorbents for siloxane compounds. Examples of such an adsorbent include a siloxane remover containing a resin having a sulfonic acid group (see Patent Document 2), and a porous material obtained by attaching a sulfonic acid group-modified metal oxide sol to a porous material (see Patent Document 2). 3, 4), a siloxane remover containing an acidic compound having a dissociation index of 2.2 or less and a molecular weight of 1000 or less in an inorganic porous material having an average pore diameter of 3 to 20 nm (see Patent Document 5), and the like. It has been known. It is described that when a resin or a porous material into which such an acidic functional group is introduced is used as an adsorbent, siloxanes can be selectively and efficiently removed.

JP 2005-177737 A JP 2011-212565 A JP 2013-103153 A JP 2013-103154 A JP 2015-44175 A

  However, when activated carbon is used as the adsorbent as in Patent Document 1, the siloxanes once adsorbed may be desorbed.

  The siloxane compound often exists in the atmosphere together with other gas components such as an organic gas component in a normal environment. For this reason, when there are many other gas components, in an adsorbent using activated carbon as described in Patent Document 1, the removal of the siloxane compound and the removal of the other gas components compete with each other. The removal efficiency (removal performance or removal capability) of the compound varies depending on the abundance of other gas components. Furthermore, the amount of other gas components present in the atmosphere often varies from day to day. For this reason, since the amounts of the siloxane compound and other gas components removed by the activated carbon fluctuate every day, it has been difficult to predict the remaining life of the adsorbent using the activated carbon or the filter using the adsorbent.

  In Patent Document 2, a strong acid-type ion exchange resin is used. However, a resin having a sulfonic acid group usually has a low ability to adsorb a siloxane compound, and there is a problem that a siloxane gas cannot be sufficiently removed regardless of whether or not the resin is supported on a porous carrier. Further, since the resin has a large molecular weight, the resin is always present in the vicinity of the sulfonic acid group. However, the resin has a low ability to adsorb the siloxane compound, and the progress of the reaction between the sulfonic acid group and the siloxane compound becomes slow. However, there is a problem that they are detached.

  Further, in Patent Document 2, cyclic siloxanes are polymerized and adsorbed by a strong acid-type ion exchange resin, and in Patent Document 5, the adsorbed siloxane gas is activated by an acidic compound, and siloxanes not activated are adsorbed. Reacts with gas and is adsorbed. As described above, Patent Documents 2 and 5 describe that siloxane compounds react with each other and are adsorbed. However, when the concentration of the siloxane compound in the air is extremely low, the reaction between the siloxane compounds hardly occurs, and thus the removal efficiency is not necessarily sufficient by this method.

  In Patent Documents 3 and 4, a sulfonic acid group-modified metal oxide sol is attached to a porous material. However, in order to obtain such a sulfonic acid group-modified metal oxide sol, it is necessary to prepare the sol by a complicated process, and an adsorbent or a chemical filter capable of efficiently removing a siloxane compound cannot be easily obtained.

  Therefore, at present, there is a need for a chemical filter that can efficiently remove a siloxane compound in a low-concentration environment and that can be easily obtained.

  Accordingly, an object of the present invention is to provide a chemical filter for removing a siloxane compound which can efficiently remove a siloxane compound under a low concentration environment and can be easily obtained. Another object of the present invention is to provide a siloxane compound removing chemical filter capable of selectively removing a siloxane compound.

  The present inventors have conducted intensive studies to achieve the above object. As a result, when an inorganic silica-based porous material having a pH of a water mixture with pure water of 7 or less is used as an adsorbent, the inorganic silica-based porous material can be used in a fluid (particularly, in air). The present inventors have found that the siloxane compound of (1) can be removed very efficiently and completed the present invention.

  That is, the present invention provides a chemical filter for removing a siloxane compound using, as an adsorbent, an inorganic silica-based porous material in which a water mixture (content ratio: 5 wt%) obtained by mixing with pure water has a pH of 7 or less. I do.

  In the chemical filter for removing a siloxane compound, the inorganic silica-based porous material includes zeolite, silica gel, silica alumina, aluminum silicate, porous glass, diatomaceous earth, hydrous magnesium silicate clay mineral, allophane, imogolite, acid clay, At least one or two or more inorganic silica-based porous materials selected from the group consisting of activated clay, activated bentonite, mesoporous silica, aluminosilicate, and fumed silica may be used.

  In the chemical filter for removing a siloxane compound, another adsorbent may be used as the adsorbent together with the inorganic silica-based porous material whose pH of the water mixture (content ratio: 5 wt%) is 7 or less.

  In the chemical filter for removing a siloxane compound, at least one selected from the group consisting of synthetic zeolite, diatomaceous earth, silica gel, and activated clay is used as the inorganic silica-based porous material in an amount of 10% with respect to the total weight of the adsorbent. % By weight or more.

In the chemical filter for removing a siloxane compound, a synthetic zeolite is included as the inorganic silica-based porous material, and a ratio (molar ratio) of SiO ₂ and Al ₂ O ₃ [SiO ₂ / Al ₂ O ₃ ] in the synthetic zeolite is: It may be 4-2000.

  In the chemical filter for removing a siloxane compound, a synthetic zeolite is included as the inorganic silica-based porous material, and the synthetic zeolite is ferrierite, MCM-22, ZSM-5, ZSM-11, mordenite, beta type, X type, It may be a synthetic zeolite having at least one skeleton structure selected from the group consisting of Y-type and offretite.

The inorganic silica-based porous material may be an inorganic silica-based porous material having a loss on ignition calculated from the following formula (1) of 7.0% or less.
Loss on ignition I (%) = (W ₁ −W ₂ ) / W ₁ × 100 (1)
W ₁ : Mass of sample after drying W ₂ : Mass of sample after ignition [In formula (1), mass of sample after drying (W ₁ ) is obtained by using an inorganic silica-based porous material at about 170 ° C. in air or vacuum. This is the mass of the inorganic silica-based porous material after heating at about 150 ° C. for 2 hours. The sample mass after ignition (W ₂ ) is the mass of the inorganic silica-based porous material obtained by igniting the dried inorganic silica-based porous material at 1000 ° C. ± 50 ° C. for 2 hours. . ]

  The chemical filter may be a chemical filter in which the adsorbent is attached to a filter substrate by a binder.

  In the chemical filter for removing a siloxane compound, the binder may be a binder in which a pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water is 7 or less.

  In the chemical filter for removing a siloxane compound, the binder may be an inorganic binder.

  In the chemical filter for removing a siloxane compound, the binder may be colloidal inorganic oxide particles.

  The structure of the chemical filter may have at least one structure selected from the group consisting of a honeycomb structure, a pleated structure, a three-dimensional network structure, a sheet packaging structure, and a sheet-like structure.

  The honeycomb structure is a honeycomb-like structure, or a cross-section is a lattice, a circle, a wave, a polygon, an irregular shape, or a shape having a curved surface in whole or in part, and the fluid is an element of the structure. May be a structure that passes through a cell.

  The chemical filter for removing a siloxane compound may be a chemical filter containing the adsorbent pelletized.

  For the pelletization, a binder in which the pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water is 7 or less may be used.

  The structure of the filter containing the pelletized adsorbent has at least one structure selected from the group consisting of a pleated structure, a pellet-filled structure, a three-dimensional mesh structure, a sheet packaging structure, and a sheet-like structure. Is also good.

  The chemical filter for removing a siloxane compound may be a chemical filter manufactured by a papermaking method.

  The chemical filter for removing a siloxane compound may be a ceramic type chemical filter.

  The chemical filter for removing a siloxane compound may be a chemical filter in which the adsorbent is attached to a filter substrate without using a binder.

  The present invention further provides a gas sensor including the chemical filter for removing a siloxane compound.

  The present invention further provides a resin composition used for the chemical filter for removing a siloxane compound, wherein the resin composition contains the inorganic silica-based porous material and a resin.

  According to the chemical filter of the present invention, the siloxane compound once adsorbed does not desorb again, so that the removal effect lasts longer than activated carbon. Further, since there is no need to react the siloxane compounds with each other in removing the siloxane compounds, the siloxane compounds can be efficiently removed even in a low-concentration environment. In addition, since it is not necessary to go through complicated steps for producing the adsorbent and the chemical filter, it can be easily obtained. Further, according to the chemical filter of the present invention, the siloxane compound can be selectively removed. Therefore, the siloxane compound can be efficiently removed even in an environment where other gas components are present together with the siloxane compound. Further, it is relatively easy to predict the remaining life of the chemical filter.

  Furthermore, according to the chemical filter of the present invention, in particular, since the siloxane compound in the air can be removed very efficiently, the amount of the adsorbent used can be extremely small, and the number of filter substrates can be reduced. Can be reduced, and energy saving, low cost, and space saving can be achieved.

It is the schematic of the ventilation test apparatus used in the Example. It is a partial schematic sectional view of the ventilation test device used in the Example. 5 is a graph showing the results of the aeration test of Example 1 (relationship between pH of a water mixture of zeolite and removal efficiency). 3 is a graph showing the results of the aeration test of Example 1 (relationship between the pH of a water mixture of silica gel, acid clay, activated clay, and diatomaceous earth and the removal efficiency). 10 is a graph showing the results of the aeration test of Example 4 (relationship between pH of a water mixture of zeolite and diatomaceous earth and removal efficiency).

[Chemical filter]
The chemical filter for removing a siloxane compound according to the present invention is a siloxane compound using an inorganic silica-based porous material having a pH of 7 or less as a water mixture (content ratio: 5 wt%) obtained by mixing with pure water as an adsorbent. It is a chemical filter for removal. In the present specification, the “chemical filter for removing a siloxane compound of the present invention” may be simply referred to as “the chemical filter of the present invention”. In addition, in the present specification, an adsorbent using an inorganic silica-based porous material having a pH of 7 or less in a water mixture (content ratio: 5 wt%) obtained by mixing with pure water is referred to as an “adsorbent of the present invention”. ". Further, in the present specification, “pH of a water mixture” refers to “pH of a water mixture (content ratio: 5 wt%)” unless otherwise specified.

(Adsorbent of the present invention)
The chemical filter of the present invention uses an inorganic silica-based porous material as an essential adsorbent. As the inorganic silica-based porous material, only one kind may be used, or two or more kinds may be used.

  In the chemical filter of the present invention, the pH of the water mixture (content ratio: 5 wt%) obtained by mixing the inorganic silica-based porous material with pure water is 7 or less (for example, 3 to 7), and is preferably. It is less than 7 (for example, 3 or more and less than 7), more preferably 3 to 6.5, and still more preferably 4 to 6. When the pH is 7 or less, the siloxane compound can be removed with high efficiency.

  In the present specification, the pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water means that the content ratio of a substance (target substance) to be mixed in the water mixture is based on the entire water mixture. It means the pH when measured under the condition of 5 wt%. For example, the pH of a water mixture (content ratio: 5 wt%) obtained by mixing the inorganic silica-based porous material with pure water is measured when the content ratio of the inorganic silica-based porous material is 5 wt%. PH. The pH of the water mixture can be measured, for example, using a pH meter. In addition, when the thing which impregnated an impregnating agent etc. to the above-mentioned inorganic silica type porous material is used as an adsorbent of the present invention, the above-mentioned “pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water” is A water mixture (content ratio: 5 wt%) of an inorganic silica-based porous material in a state before the impregnating agent or the like is impregnated (that is, a state in which the impregnating agent or the like is not impregnated) obtained by mixing with pure water. shall refer to pH.

  In this specification, the water mixture (content ratio: 5 wt%) can be produced, for example, by the following “method of producing a water mixture (content ratio: 5 wt%)”.

Preparation method of water mixture (content ratio: 5 wt%) The above water mixture (content ratio: 5 wt%) is, for example, a sample to be measured for the pH of the water mixture (“object”) so that the content ratio is 5 wt%. The sample may be referred to as “sample”), mixed with pure water, stirred sufficiently, and allowed to stand. Although pure water is used for preparing the water mixture, a mixed solvent of an organic solvent and pure water may be used. However, when an organic solvent is used, the acid dissociation constant greatly varies depending on the type and concentration of the organic solvent. Therefore, in general, a water-soluble organic solvent such as alcohol, which does not significantly affect pH, is used. Concentration. Note that the above “wt%” has the same meaning as “wt%”. In order to prepare a water mixture having a content ratio of 5 wt%, specifically, for example, 5 g of a target sample is measured using a scale or the like, and pure water is further added to make the whole 100 g. It can be produced by stirring. For example, a water mixture (content ratio: 5 wt%) of an inorganic silica-based porous material can be prepared using the inorganic silica-based porous material as the target sample.

The inorganic silica-based porous material used in the chemical filter of the present invention is not particularly limited, but has a specific surface area (BET specific surface area) of 10 m ² / g or more (for example, 10 to 800 m ² / g). It is preferably 50 m ² / g or more (for example, 50 to 750 m ² / g), more preferably 100 m ² / g or more (for example, 100 to 700 m ² / g).

The inorganic silica-based porous material is not particularly limited, but the content of SiO ₂ in the porous material may be 5% by weight or more (for example, 5 to 100% by weight), and preferably 50% by weight or more. And more preferably 65% by weight or more, more preferably 75% by weight or more.

  Examples of the inorganic silica-based porous material include, but are not particularly limited to, zeolite (eg, synthetic zeolite, natural zeolite, etc.), silica gel, silica alumina, aluminum silicate, porous glass, diatomaceous earth, and hydrous magnesium silicate clay. Minerals (eg, talc), allophane, imogolite, acid clay, activated clay, activated bentonite, mesoporous silica, aluminosilicate, fumed silica, and the like. By using the inorganic silica-based porous material as an adsorbent, the siloxane compound can be removed with high efficiency. Among them, zeolite, diatomaceous earth, silica gel, and activated clay are preferred, and synthetic zeolite, diatomaceous earth, silica gel, and activated clay are more preferred. When zeolite (particularly, synthetic zeolite), diatomaceous earth, silica gel, or activated clay is used as the adsorbent, the siloxane compound can be efficiently removed over a longer period of time. Above all, when zeolite (particularly, synthetic zeolite) or silica gel is used as the inorganic silica-based porous material, the removal efficiency of both the linear siloxane compound and the cyclic siloxane compound tends to be remarkably excellent. When silica gel or diatomaceous earth is used as the inorganic silica-based porous material, the siloxane compound tends to be more selectively removed. As the inorganic silica-based porous material, only one kind may be used, or two or more kinds may be used. The synthetic zeolite includes artificial zeolite. In addition, only one kind of zeolite may be used, or two or more kinds may be used.

  The zeolite is a porous material having a skeleton mainly composed of a silicon element (Si), an aluminum element (Al), and an oxygen element (O), and a part or all of the aluminum element ( Al) may be replaced by a trivalent metal element such as iron element (Fe), boron element (B), gallium element (Ga); or a divalent metal element such as zinc element (Zn). .

  The pore structure of the zeolite is not particularly limited. The number of member rings of the zeolite is not particularly limited, but is, for example, 4 to 20, preferably 8 to 20, and more preferably 10 to 12. Note that the number of member rings of zeolite is represented by the number of O atoms in the structure of the largest pore ring among the pore rings contained in zeolite. Further, the pore connection (channel system) of the zeolite is not particularly limited, but is preferably 1 to 3 dimensions, more preferably 2 to 3 dimensions, and further preferably 3 dimensions. In particular, zeolite having a pore structure in which the number of ring members is 12 and pore connection is three-dimensional (particularly, synthetic zeolite) is preferable. When the number of ring members and / or pore connection of the zeolite is within the above range, the removal efficiency of the siloxane compound tends to be higher.

  Although it does not specifically limit as said synthetic zeolite, For example, A type, ferrierite, MCM-22, ZSM-5, ZSM-11, SAPO-11, mordenite, beta type, X type, Y type, L type, chabazite And synthetic zeolites having a skeletal structure such as offretite. As the skeletal structure, ferrierite, MCM-22, ZSM-5, ZSM-11, mordenite, beta type, X type, Y type, and offretite are preferable. The above-mentioned synthetic zeolite may use one kind of zeolite having a skeletal structure, or may use two or more kinds of zeolites in combination.

  Examples of the artificial zeolite include, for example, zeolite produced from waste containing silicon and aluminum, such as coal ash discharged from a coal-fired power plant and paper sludge incinerated ash discharged from a paper mill. The artificial zeolite may be used alone or in combination of two or more.

  Examples of the natural zeolite include, but are not particularly limited to, clinoptilolite (clinoptilolite), mordenite (mordenite), chabazite, natrolite, gonnardite, edding tonite, analsim, leucite, yugawaralite, gismondyne, and polingite. , Phillipsite, chabazite, erionite, faujasite, ferrierite, mutinaite, chernihiite, heurandite, stilbite, urecite, aluminosilicate, belolosilicate (logianite, shanhalite, etc.), gincosilicate (gaultight) ). The natural zeolite may be used alone or in combination of two or more.

  In the zeolite, the pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water is 7 or less (for example, 3 to 7), preferably less than 7 (for example, 3 or more and less than 7), and more. It is preferably from 3 to 6.8, more preferably from 3.5 to 6.7, particularly preferably from 4 to 6.5. In addition, the water mixture of zeolite (content ratio: 5 wt%) can be produced using zeolite as a target sample by the above-mentioned “method for producing a water mixture (content ratio: 5 wt%)”.

The ratio (molar ratio) of SiO ₂ to Al ₂ O ₃ [molar ratio] [SiO ₂ / Al ₂ O ₃ ] in the above synthetic zeolite is not particularly limited, but may be 4 to 2,000 from the viewpoint of siloxane compound removal efficiency. , Preferably 5 to 1500, more preferably 10 to 1000, and still more preferably 12 to 600. The above [SiO ₂ / Al ₂ O ₃ ] is considered as an index indicating the hydrophilicity or hydrophobicity of zeolite. When [SiO ₂ / Al ₂ O ₃ ] is high (that is, the silica ratio is high and the alumina ratio is low), the hydrophobicity tends to increase. On the other hand, when [SiO ₂ / Al ₂ O ₃ ] is low (that is, the silica ratio is low and the alumina ratio is high), the hydrophilicity tends to increase. If the hydrophilicity is too high (that is, the hydrophobicity is too low), the surface of the skeleton is covered with water molecules, and it becomes difficult for the hydrophobic siloxane compound to approach the adsorption site (the place where the substance is adsorbed). If the hydrophilicity is too low (that is, the hydrophobicity is too high), the acid sites in the zeolite will decrease, and the removal efficiency of the siloxane compound tends to decrease. Therefore, for example, by setting [SiO ₂ / Al ₂ O ₃ ] within the above range, the hydrophilicity or hydrophobicity of the zeolite can be appropriately adjusted, and the siloxane compound removal efficiency can be made more excellent. In particular, when the siloxane compound is a cyclic siloxane compound, the synthetic zeolite preferably has a high hydrophobicity, and more preferably has a high [SiO ₂ / Al ₂ O ₃ ].

The zeolite is not particularly limited, but may include a cation in the framework structure. Examples of the cation include, but are not particularly limited to, a hydrogen ion (H ⁺ ); an ammonium ion (NH ₄ ⁺ ); an alkyl-substituted ammonium ion (eg, a methyl ammonium ion ((CH ₃ ) H ₃ N ⁺ ); Dimethyl ammonium ion ((CH ₃ ) ₂ H ₂ N ⁺ ), trimethyl ammonium ion ((CH ₃ ) ₃ HN ⁺ ), tetramethyl ammonium ion ((CH ₃ ) ₄ N ⁺ ), etc .; aryl- or aralkyl-substituted ammonium Ions; alkali metal ions such as lithium ion (Li ⁺ ), sodium ion (Na ⁺ ), potassium ion (K ⁺ ); magnesium ion (Mg ²⁺ ), calcium ion (Ca ²⁺ ), barium ion (Ba ²⁺⁾ ) an alkaline earth metal such as ion; zinc ion (Zn ^2+), tin ions (Sn ^2+, Sn ^4+), Ions (Fe ^2+, Fe ^3+), a platinum ion (Pt ^2+), palladium ion (Pd ^2+), titanium ions (Ti ^3+), silver ions (Ag ^+), copper ion (Cu ^+, Cu ^{2 +} ), Transition metal ions such as manganese ions (Mn ²⁺ , Mn ⁴⁺ ) and cobalt ions (Co ²⁺ ); and gallium ions (Ga ⁺ ). The cation may be contained alone or in combination of two or more. The content of the cation in the zeolite is not particularly limited.

  The specific surface area (BET specific surface area), average particle diameter (average particle diameter), average pore diameter (diameter), total pore volume, and the like of the zeolite are not particularly limited. In addition, only one kind of zeolite may be used, or two or more kinds may be used.

  As the zeolite, an acid-treated product obtained by acid-treating a natural zeolite or a synthetic zeolite, a hydrothermally-treated product obtained by hydrothermally treating a natural zeolite or a synthetic zeolite, an ammonium-treated product obtained by calcining an ammonium-type zeolite, Proton-type zeolites may be used. In addition, as the acid used for the acid treatment, a known or commonly used acid can be used, and examples thereof include hydrochloric acid, nitric acid, and citric acid. The type of acid used for the acid treatment, the concentration of the acid in the acid aqueous solution used for the acid treatment, the acid treatment time, and the like are not particularly limited.

  The acid-treated product and the hydrothermally-treated product are presumed to be because the silanol groups in the zeolite increase due to the cation and the aluminum element in the zeolite being eliminated by the acid in the acid treatment or the heated steam in the hydrothermal treatment. In addition, the pH of the water mixture becomes 7 or less, and the removal efficiency of the siloxane compound increases.

  Examples of the proton-type zeolite include, for example, those obtained by replacing at least a part of cations of all cations other than hydrogen ions (for example, metal ions and ammonium ions) in natural zeolites and synthetic zeolites with hydrogen ions, Synthetic zeolites prepared to contain a large amount of hydrogen ions are exemplified. The proton-type zeolite can also be produced by, for example, a method in which a cation such as a sodium ion in a natural zeolite or a synthetic zeolite is ion-exchanged to an ammonium ion, and then calcined. In addition, generally, cations in zeolites replaced with hydrogen ions are called proton-type zeolites, and the proton-type zeolites have at least some cations in zeolite replaced with hydrogen ions. It is only necessary that all cations in the zeolite be replaced by hydrogen ions.

  Proton-type zeolites are sometimes used as catalysts, but are not commonly used as adsorbents. It is considered that zeolite may be used as an adsorbent, but most of the zeolite used as an adsorbent is basic, that is, the pH of a water mixture exceeds 7. As a specific embodiment in which zeolite is used as an adsorbent, for example, a molecular sieve is famous, but the substance removed by the molecular sieve is water, which is present in the molecular sieving function of zeolite and in zeolite. It is mainly removed by coordinating water to metal ions such as Na ions. When utilizing the Na ions in the zeolite in this way, the pH of the water mixture of the zeolite to be used exceeds 7. Furthermore, the use of solid acid-type zeolites as an adsorbent is extremely rare. For example, there is a method in which a basic compound such as ammonia is removed by a neutralization reaction using the acid of a solid acid type zeolite and the ion exchange ability. However, at present, removal targets are limited to inorganic compounds and basic compounds. That is, there has been no example of using a zeolite whose pH of a water mixture is 7 or less for removing a siloxane compound which is an organic compound.

  The acid clay is not particularly limited, and acid clay produced in various places can be used. For example, acid clay from Niigata Prefecture, acid clay from Yamagata Prefecture and the like can be mentioned. As the acid clay, only one kind may be used, or two or more kinds may be used.

  The activated clay is obtained by acid-treating the acid clay, for example, by treating the acid clay with a mineral acid such as sulfuric acid to such an extent that the entire basic structure of montmorillonite is not destroyed. Metal oxides such as oxides are eluted, and specific surface area and pore volume are increased. As the activated clay, only one kind may be used, or two or more kinds may be used.

  The acid clay and the activated clay have a pH of 7 or less (for example, 3 to 7), preferably less than 7 (for example, 3 or more) in a water mixture (content ratio: 5 wt%) obtained by being mixed with pure water. 7), more preferably 3 to 6.5, still more preferably 3.2 to 5, particularly preferably 3.5 to 4.7. The water mixture of the acid clay (content ratio: 5 wt%) and the water mixture of the activated clay (content ratio: 5 wt%) are obtained by the above-mentioned “method of preparing a water mixture (content ratio: 5 wt%)”. White clay can be produced as a target sample.

  The diatomaceous earth is not particularly limited, and diatomaceous earth produced in various places can be used. For example, diatomaceous earth from diatomaceous earth (diatom shale) from Wakkanai in Hokkaido, diatomite from Nasuko in Akita Prefecture, diatomite from Hiruzen in Okayama Prefecture, diatomite from Kuju in Oita Prefecture, and diatomite from diatomaceous earth (diatom mudstone) from Noto, Ishikawa Prefecture. You may. Among them, diatomaceous earth from Wakkanai, Hokkaido, is preferred. The diatomaceous earth may be used alone or in combination of two or more.

  The pH of the water mixture (content ratio: 5 wt%) obtained by mixing the diatomaceous earth with pure water is 7 or less (for example, 3 to 7), preferably less than 7 (for example, 3 or more and less than 7), and more. It is preferably from 3 to 6.7, more preferably from 3.2 to 6.5, and particularly preferably from 3.5 to 6.2. The diatomaceous earth water mixture (content ratio: 5 wt%) can be prepared using the diatomaceous earth as a target sample by the above-mentioned “method of preparing a water mixture (content ratio: 5 wt%)”.

  As the silica gel, an acid-treated product obtained by treating silica gel with an acid and washing away the acid used in the treatment with water or the like may be used. In addition, as the acid used for the acid treatment, a known or commonly used acid can be used, and examples thereof include hydrochloric acid, nitric acid, and citric acid. The type of acid used for the acid treatment, the concentration of the acid in the acid aqueous solution used for the acid treatment, the acid treatment time, and the like are not particularly limited.

  Inorganic silica-based porous materials other than synthetic zeolite, acid clay, activated clay, and diatomaceous earth (sometimes referred to as “other inorganic silica-based porous materials”) are mixed with pure water to obtain a water mixture (content ratio) : 5 wt%) is 7 or less (for example, 3 to 7), preferably less than 7 (for example, 3 or more and less than 7), more preferably 3 to 6.5, and still more preferably 3.5 to 6. 3, particularly preferably 4 to 6. The water mixture (content ratio: 5 wt%) of the other inorganic silica-based porous material was obtained by subjecting the other inorganic silica-based porous material to the target sample according to the above-mentioned “Method for preparing water mixture (content ratio: 5 wt%)”. It can be manufactured as

In the inorganic silica-based porous material other than the synthetic zeolite, the content of SiO ₂ is not particularly limited, but is 50% by weight or more (for example, 50% by weight) with respect to the total weight (100% by weight) of the inorganic silica-based porous material. To 100% by weight), preferably 60% by weight or more, more preferably 70% by weight or more.

  The inorganic silica-based porous material is not particularly limited, but the ignition loss is preferably 7.0% or less (for example, 2.5 to 7.0%), and more preferably 3.0 to 6%. 0.0%, and more preferably 3.5 to 4.5%. When activated clay having a pH of the water mixture of 7 or less and the loss on ignition within the above range is used as the inorganic silica-based porous material, the siloxane compound removal performance tends to be more excellent. In particular, for activated clay, diatomaceous earth, and silica gel, the loss on ignition is preferably within the above range. In the case of silica gel, the ignition loss is more preferably from 3.0 to 7.0%, and still more preferably from 3.5 to 6.0%.

The ignition loss can be determined, for example, by referring to JIS K1150 (1994). Specifically, the ignition loss is determined by the following equation (1).
Loss on ignition I (%) = (W ₁ −W ₂ ) / W ₁ × 100 (1)
W ₁ : Mass of sample after drying W ₂ : Mass of sample after ignition

The sample mass after drying (W ₁ ) is the mass of the inorganic silica-based porous material after the inorganic silica-based porous material is heated at about 170 ° C. in air or at about 150 ° C. under vacuum for 2 hours. On the other hand, the mass of the sample after ignition (W ₂ ) is the value of the inorganic silica-based porous material obtained by igniting the inorganic silica-based porous material as the sample after drying at 1000 ° C. ± 50 ° C. for 2 hours. Mass. The weight of the sample after drying (W ₁ ) and the weight of the sample after ignition (W ₂ ) can be measured using a balance, or can be measured by thermogravimetry (TG). For more detailed conditions for obtaining the above-mentioned ignition loss, JIS K1150 (1994) can be referred to.

  The above-mentioned loss on ignition is considered to be an index indicating the hydrophilicity or hydrophobicity of the inorganic silica-based porous material. When the ignition loss is high, the number of silanol groups in the inorganic silica-based porous material is large, and the hydrophilicity tends to be high. If the hydrophilicity is too high (that is, the hydrophobicity is too low), the surface of the inorganic silica-based porous material is covered with water molecules, so that the hydrophobic siloxane compound does not easily approach an adsorption site (adsorption place), and the siloxane compound Removal performance tends to decrease. On the other hand, when the ignition loss is low, the number of silanol groups in the inorganic silica-based porous material is small, and the hydrophobicity tends to be high. If the hydrophobicity is too high (that is, the hydrophilicity is too low), the number of silanol groups is small, and the gas siloxane compound removal performance tends to decrease. For this reason, by setting the ignition loss within the above range, the hydrophilicity or hydrophobicity of the inorganic silica-based porous material can be appropriately adjusted, and the siloxane compound removal efficiency can be further improved. The number of the silanol groups can be expressed as “the number of silanol groups” defined in JIS K1150 (1994), and can be determined from the ignition loss.

  The inorganic silica-based porous material is not particularly limited, but is preferably free from an impregnating agent or the like. That is, it is preferable that the inorganic silica-based porous material does not include an inorganic silica-based porous material to which an additive or the like is attached. Examples of the adhering agent include an adhering agent for an acidic substance and an adhering agent for a basic substance. When an impregnating agent of an acidic substance is attached, the skeleton of the inorganic silica-based porous material may change or pores may be filled with the acidic substance.

  The adsorbent of the present invention is not particularly limited, but may contain an adsorbent (another adsorbent) other than the inorganic silica-based porous material whose pH of the water mixture is 7 or less, if necessary. That is, as the adsorbent of the present invention, another adsorbent may be used together with the inorganic silica-based porous material whose pH of the water mixture is 7 or less. Examples of the other adsorbent include porous materials other than the inorganic silica-based porous material in which the pH of the water mixture is 7 or less, other silica, clay minerals, activated carbon, alumina, and glass. By using the other adsorbent as the adsorbent in combination, a chemical filter having the effect of the other adsorbent in addition to the effect of the present invention can be obtained.

  The content of the inorganic silica-based porous material in which the pH of the water mixture in the adsorbent of the present invention (in the total adsorbent) is 7 or less is not particularly limited, but from the viewpoint of the removal efficiency of the siloxane compound, Is preferably 10% by weight or more (for example, 10 to 100% by weight), more preferably 30% by weight or more, further preferably 50% by weight or more, particularly preferably 70% by weight, based on the total weight (100% by weight) of That is all.

  The adsorbent of the present invention includes, among others, a zeolite (particularly, synthetic zeolite), diatomaceous earth, silica gel, or activated clay as an inorganic silica-based porous material having a pH of a water mixture of 7 or less, and a total weight (100 wt. %) (E.g., 10 to 100% by weight, preferably 50% by weight or more, more preferably 70% by weight or more). When the inorganic silica-based porous material contains two or more of zeolite (particularly, synthetic zeolite), diatomaceous earth, silica gel, and activated clay, the content is the total content of the two or more. .

  The chemical filter of the present invention is not particularly limited as long as it uses an inorganic silica-based porous material in which the pH of a water mixture (content ratio: 5 wt%) is 7 or less as an adsorbent. Examples of the chemical filter include a chemical filter in which the adsorbent of the present invention is attached (fixed) to a filter substrate. When the adsorbent of the present invention also has a function as a binder, the adsorbent can be attached to the filter substrate without using the binder. However, the adsorbent of the present invention uses the binder to form the filter base. Preferably, it is attached to the material. That is, the chemical filter may be a chemical filter in which the adsorbent of the present invention is attached to the filter substrate without using a binder (or the only adsorbent of the present invention is attached). It is preferable that the adsorbent of the present invention is a chemical filter in which the adsorbent of the present invention is attached to a filter base material using a binder.

  The adsorbent of the present invention is not particularly limited, but may be pelletized. That is, the adsorbent of the present invention may be a pelletized adsorbent. That is, the chemical filter of the present invention may include the adsorbent of the present invention that has been pelletized. The pelletization can be performed, for example, by granulating the adsorbent powder of the present invention using the binder.

  Further, the adsorbent of the present invention may be used as a resin composition by mixing with a resin. Examples of the resin composition include resin pellets and sheets (for example, sheets prepared using the resin pellets). Examples of the sheet include a film and a fibrous base material (woven fabric, nonwoven fabric, etc.).

  Known or commonly used thermoplastic resins can be used as the resin in the resin composition. Examples of the resin include olefin resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polypropylene (PP); ionomers; ethylene-acrylic acid copolymer (EAA); Acid copolymer (EMAA), ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate copolymer (EMA), ethylene-methyl methacrylate copolymer Copolymers such as union (EMMA) and the like can be mentioned.

  The resin is preferably a resin having a high melt flow rate (MFR) (for example, 10 g / 10 min or more), a low melting point (low softening point), and excellent low-temperature drawdown properties. When the resin has a high MFR, it is easy to secure a certain flow characteristic even when the MFR is lowered by adding the adsorbent of the present invention. If the melting point is low, the resin is softened at a low temperature, so that the extrudability at a low temperature is improved and the resin tends to be hardly foamed. If the resin has an excellent low-temperature drawdown property, the extrusion moldability when the adsorbent of the present invention is added tends to be improved.

  It is preferable that the content of the adsorbent of the present invention in the resin composition is as large as possible in a target shape from the viewpoint of increasing the efficiency of removing the siloxane compound. For example, when the resin composition is a sheet, it is preferable to increase the resin composition within a range in which the sheet can be formed. The content of the adsorbent of the present invention in the resin composition is not particularly limited, but is preferably 1 to 200 parts by weight, more preferably 5 to 150 parts by weight, based on the total weight of the resin (100 parts by weight). More preferably, it is 10 to 120 parts by weight. When the inorganic silica-based porous material in the adsorbent of the present invention is zeolite, diatomaceous earth, or activated clay, the content is preferably 50 to 200 parts by weight, more preferably 70 to 120 parts by weight.

(Filter substrate)
The filter base is not particularly limited, and those generally used as filter bases for chemical filters can be used. Examples of the filter substrate include a fibrous substrate (woven or non-woven fabric) composed of fibers such as organic fibers and inorganic fibers, a foam composed of paper and polyurethane foam, a refractory metal oxide, and the like. Examples include a filter substrate using a refractory inorganic substance (for example, a metal such as aluminum, ceramics, and the like). The shape of the woven fabric of the fibrous base material is not particularly limited, and examples thereof include woven fibers in a mesh shape. Among them, a fibrous base material is preferable as the filter base material.

  Examples of the fibers in the fibrous base material include inorganic fibers such as silica-alumina fibers, silica fibers, alumina fibers, mullite fibers, glass fibers, rock wool fibers, and carbon fibers; polyethylene fibers, polypropylene fibers, nylon fibers, and polyester fibers. (Eg, polyethylene terephthalate fiber), organic fibers such as polytetrafluoroethylene fiber, polyvinyl alcohol fiber, aramid fiber, pulp fiber, rayon fiber and the like. Among the above, inorganic fibers are preferable, and glass fibers are more preferable, from the viewpoint of increasing the strength of the chemical filter and the viewpoint of less contamination due to outgas from the fibers. That is, a fibrous substrate (glass cloth (glass cloth)) using glass fibers is preferable as the filter substrate. The above fibers may be used alone or in combination of two or more. Further, the shapes of the inorganic fibers and the organic fibers are not particularly limited.

(Binder)
The binder can be used to promote adhesion of the adsorbent to the filter substrate or to pelletize the adsorbent. The binder is not particularly limited, and a known or commonly used binder for a filter (for example, for an air filter, a chemical filter, or the like) can be used. The binder may be an organic binder or an inorganic binder. The binder is not particularly limited, but is preferably an inorganic binder. As the binder, only one kind may be used, or two or more kinds may be used.

  The binder may be acidic or basic, but is preferably acidic. When the binder is acidic, the removal efficiency of the siloxane compound tends to further increase. The acidic binder has a pH of 7 or less (for example, 3 to 7), preferably less than 7 (for example, 3 or more and less than 7) in a water mixture (content ratio: 5 wt%) obtained by being mixed with pure water. It is more preferably from 3 to 6.8, even more preferably from 3.5 to 6.7, particularly preferably from 4 to 6.5. The water mixture of the binder (content ratio: 5 wt%) can be produced using the binder as a target sample by the above-mentioned “method of producing a water mixture (content ratio: 5 wt%)”. When the binder is a binder containing a solvent such as colloidal silica, the content ratio is a content ratio of a solid content in the binder with respect to the water mixture.

  Examples of the organic binder include a polyethylene resin, a polypropylene resin, an acrylic resin such as methyl methacrylate, an ABS resin, a polyester resin such as PET, a phenol resin, an epoxy resin, a urethane resin, a vinyl acetate resin, and a polyvinyl resin. Alcohol, cellulose such as carboxymethylcellulose, and gum arabic are exemplified. As the organic binder, only one kind may be used, or two or more kinds may be used.

  The inorganic binder is preferably in the form of particles that do not completely cover the surface of the inorganic silica-based porous material, for example, sodium silicate, silica sol, alumina sol, colloidal silica, colloidal alumina, colloidal tin oxide, colloidal Inorganic oxide particles such as titanium oxide and the like are preferable, and among them, colloidal inorganic oxide particles such as colloidal silica, colloidal alumina, colloidal tin oxide, and colloidal titanium oxide are preferable. Among them, colloidal silica is preferable. As the inorganic binder, only one kind may be used, or two or more kinds may be used.

  The average particle diameter (primary particle diameter), specific surface area (BET specific surface area), average pore diameter (diameter), total pore volume, and the like of the inorganic binder are not particularly limited.

(Structure of chemical filter)
The structure of the chemical filter of the present invention is not particularly limited, and examples thereof include a honeycomb structure, a pleated structure, a pellet filling structure, a three-dimensional mesh structure, a sheet packaging structure, and a sheet-like structure. Among these, a honeycomb structure, a pleated structure, and a three-dimensional network structure are preferable, and a honeycomb structure is particularly preferable from the viewpoint of suppressing pressure loss. When a pelletized adsorbent (pellet) is used as the adsorbent of the present invention, it is not particularly limited, but preferably has a pleated structure, a pellet filling structure, or a three-dimensional network structure. The chemical filter of the present invention may have only one type of structure, or may have a combination of two or more types of structures.

  In addition to the honeycomb structure, the honeycomb structure may have, for example, a lattice shape, a circular shape, a wavy shape, a polygonal shape, an irregular shape, a shape having a curved surface in whole or in part, or the like. , Air) can pass through the cells that are the elements of the structure.

  The honeycomb structure includes, for example, a structure obtained by alternately laminating a corrugated sheet and a flat sheet formed by corrugating (corrugated honeycomb structure), a pleated sheet and a flat sheet. The structure includes a structure in which a pleated sheet and a flat sheet are sequentially stacked at right angles to the ventilation direction.

  As the chemical filter of the present invention having a honeycomb structure, for example, a filter substrate using a fibrous substrate is a chemical filter having a corrugated honeycomb structure, and a filter substrate using a fibrous substrate has a honeycomb structure. Chemical filters having a honeycomb structure in which a metal filter base material such as aluminum has a honeycomb structure.

  The pleated structure includes, for example, a structure having a bellows shape processed so that a waveform or a V-shape is continuous for the purpose of efficiently expanding a filtration area in a limited space.

  The pellet filling structure includes, for example, a structure in which the pelletized adsorbent is filled in a casing having a structure through which a fluid (particularly, gas) can pass. If the particle size of the powder of the adsorbent is large enough to be held in the casing, instead of the above-mentioned pellet filling structure, it is not pelletized, and the structure is such that the powder is filled in the casing as it is. You can also.

  The three-dimensional network structure is, for example, a network formed by three-dimensionally processing a foam formed of the polyurethane foam or the like, glass fiber (glass wool or the like), rock wool fiber, or fiber of the fibrous base material. Preferable examples include a structure having a filter base material of a structure, and polytetrafluoroethylene made into a needle fiber.

  The sheet packaging structure includes, for example, a structure in which an air-permeable sheet such as a nonwoven fabric or PTFE is formed into a bag of an arbitrary size, and the inside thereof is filled with an adsorbent. The particle size of the adsorbent may be pelletized so that the particles of the adsorbent do not leak out of the sheet. However, depending on the sheet, the powder may be used as it is.

  The above-mentioned sheet-like structure is formed by molding a sheet of the above-mentioned resin composition (composition including the adsorbent and the resin of the present invention) into a bag of an arbitrary size (bag) or affixing the inner wall surface of a container. Structure (wallpaper) and the like. In this case, the inside of the bag or the container may or may not be filled with the adsorbent. In the case of the sheet-like structure, for example, a product (semiconductor or the like) to be protected from contamination by a siloxane compound can be used as a chemical filter of the present invention by putting it in a bag or a container.

(Method of Manufacturing Chemical Filter of the Present Invention)
The method for producing the chemical filter of the present invention is not particularly limited, and any known or commonly used method for producing a chemical filter having an adsorbent can be used. The chemical filter of the present invention is not particularly limited, but for example, has at least a step of adsorbing the adsorbent of the present invention to a filter substrate (adsorbent adhering step). Although the method for producing the chemical filter of the present invention is not particularly limited, it may include a step (another step) other than the adsorbent attaching step. Moreover, you may purchase a commercially available filter base material and use the filter base material as it is.

  In the adsorbent adhering step, the adsorbent of the present invention is attached, for example, by suspending the filter base material containing the adsorbent of the present invention, a solvent (eg, water), and, if necessary, the binder. After dipping in the suspension, it can be removed from the suspension and dried. The suspension may contain an antisettling agent as long as the effects of the present invention are not impaired.

  The adhesion of the adsorbent of the present invention, in addition, the filter substrate, after immersion in a suspension containing the solvent and the binder as needed, taken out of the suspension, dried, It can also be carried out by dispersing and adsorbing the adsorbent of the present invention on the substrate surface.

  In addition, the adsorbent of the present invention can be attached by spraying the mixed solution containing the adsorbent of the present invention, the above-mentioned solvent, and, if necessary, the above-mentioned binder onto the above-mentioned filter substrate (particularly, non-woven fabric) using a spray or the like. It can also be performed by coating and attaching.

  The adhesion of the adsorbent of the present invention is, in addition, the above-mentioned filter substrate, pellets produced by granulating the powder of the adsorbent of the present invention, adhered with an adhesive or the like, or filled inside the filter substrate You can also do it. When granulating the powder of the adsorbent of the present invention, the above binder may be mixed as necessary. When the adsorbent powder of the present invention is mixed while containing the binder and the solvent (preferably water) in appropriate amounts, the mixture exhibits clay-like viscosity and plasticity, thereby enabling granulation.

  Alternatively, the adsorbent of the present invention can be attached by using a polytetrafluoroethylene resin which has been converted into a needle-like fiber and causing the needle-like fiber to capture and carry the adsorbent of the present invention.

  Alternatively, the adsorbent of the present invention may be attached while the adsorbent of the present invention is contained in the nanofiber. Known or commonly used nanofibers can be used as the nanofibers. The nanofibers can also be produced by a known or commonly used method for producing nanofibers. Examples of the method for producing the nanofiber include an electrospinning (ES) method (electrospinning and electrostatic spinning), a melt blow method, and a composite melt spinning method. In the above ES method, a high voltage is applied to a suspension in which the adsorbent of the present invention is dispersed in a polymer solution, and the suspension is sprayed on a ground surface (for example, a filter substrate having a zero potential surface (for example, a nonwoven fabric)). Do. In the ES method, when the suspension is sprayed at a high voltage, nanofibers containing the adsorbent of the present invention are formed.

  In the case of a chemical filter using a filter substrate to which the adsorbent does not easily adhere (for example, a metal filter substrate or the like), the adsorbent of the present invention is attached to the filter substrate using an adhesive. You may go.

  In the chemical filter having the pleated structure, the adsorbent of the present invention is attached, for example, by adhering the adsorbent powder or the pelletized adsorbent of the present invention between two nonwoven fabric filter substrates. It can also be performed by sandwiching with an agent or the like.

  Examples of the other steps include a step of processing a filter substrate (filter substrate processing step). The order of the filter substrate processing step and the adsorbent adhering step is not particularly limited, but from the viewpoint of workability, the order of the filter substrate processing step and the adsorbent adhering step is preferable.

  Examples of the filter substrate processing step include, as described above, a step of performing corrugation processing on the filter substrate, a step of forming a honeycomb structure, and a step of providing pores in the filter substrate. In the filter substrate processing step, only one step may be performed, or two or more identical or different steps may be performed. When two or more filter base material processing steps are performed, the order is not particularly limited.

  Further, the chemical filter of the present invention may be a chemical filter manufactured by a papermaking method. The chemical filter manufactured by the papermaking method is, for example, a chemical filter having at least the fibrous base material and the adsorbent of the present invention, and contains the fibers constituting the fibrous base material and the adsorbent of the present invention. A substance (flock) produced by adding a flocculant to the suspension is formed into a sheet by a wet papermaking method and then heat-treated.

  Further, the chemical filter of the present invention may be a ceramic type chemical filter. The ceramic type chemical filter can be manufactured by a known or commonly used processing method of ceramic materials. For example, the adsorbent of the present invention can be manufactured by molding and firing together with a ceramic raw material. Specifically, for example, after weighing and kneading the adsorbent of the present invention, the binder, the pore former, and other ceramic raw materials as necessary, a kneaded material is prepared, and the kneaded material is extruded with a screw. Extrusion is carried out by an extruder such as an extruder to produce a molded body. The obtained molded body is dried and fired to obtain a porous ceramic-type chemical filter. The ceramic-type chemical filter is not particularly limited, but is preferably a ceramic-type chemical filter having a honeycomb structure. The end face of the ceramic type chemical filter can be appropriately processed to a predetermined length with a grinding tool such as a diamond cutter or a diamond saw.

  Among the above, the chemical filter of the present invention is particularly preferably a chemical filter having a honeycomb structure in which a plurality of corrugated sheets on the surface of which the adsorbent of the present invention is adhered by an inorganic binder are laminated via a thin sheet.

  Although not particularly limited, it is preferable that the chemical filter of the present invention does not include an adsorbent to which an impregnant of an acidic substance is impregnated. That is, it is preferable that the chemical filter of the present invention does not include an adsorbent to which an impregnant of an acidic substance is impregnated.

(Frame)
The chemical filter of the present invention is preferably used as a framed chemical filter (framed chemical filter). The framed chemical filter is obtained by placing the chemical filter (filter medium) of the present invention in which the adsorbent of the present invention is adhered to a filter substrate in a frame. Examples of the framed chemical filter include a panel-type filter, a cell-type filter, and a chemical filter for piping. Note that both the filter medium and the framed chemical filter correspond to the chemical filter of the present invention.

  Examples of the panel-type filter include a chemical filter in which an edge of a plate-like filter material is fitted into a frame, such as a frame. The above-mentioned panel-type filter is generally used to allow a fluid containing a siloxane compound to pass through in a thickness direction of a plate-shaped filter medium. The shape of the frame is not particularly limited, and can be appropriately selected depending on the use mode. Examples of the shape of the frame include a polygonal shape (for example, a triangular shape, a square shape, a hexagonal shape, a frame shape, etc.), a circular shape, an elliptical shape, a shape in which some or all corners of a polygon are rounded, And the like. In addition, only one sheet of the plate-shaped filter medium may be used, or a plurality of the filter mediums may be used.

  As the above-mentioned cell-type filter, for example, a filter in which a filter medium is arranged such that a fluid containing a siloxane compound passes through the filter medium inside a cell having a hexahedral shape (cube, rectangular parallelepiped, etc.). Examples of the cell-type filter include a chemical filter in which a filter medium has a series of bent portions so as to form a continuous V-shape, and the bent portions are arranged so as to face the ventilation direction. In addition, the above-mentioned cell type filter may be a chemical filter arranged in a folding screen shape such that each of the above-mentioned bent portions is cut, that is, a plurality of filter media have a V-shaped structure. In a cell-type filter in which a filter medium is arranged in a V-shaped structure, a fluid containing a siloxane compound is arranged to pass in the thickness direction of the filter medium arranged in a V-shaped structure.

  As the chemical filter for piping, for example, a chemical filter in which a filter medium is packed in at least a part of the inside of a pipe having a tubular shape (for example, a cylindrical shape, a rectangular tubular shape, or the like) is used. In the portion where the filter medium is packed, it is preferable that the filter medium be packed on the entire cross section of the cylindrical pipe so that all the fluid containing the siloxane compound passes through the filter medium. The piping chemical filter can be preferably used for pressure piping.

  As a method of using the chemical filter of the present invention, for example, by using the power of a ventilation fan or the like, air containing the substance to be removed is forcibly introduced into an apparatus equipped with the chemical filter, and the removal target is removed. In addition to the ventilation method that removes substances, instead of using power to introduce air into a device equipped with a chemical filter, the substance to be removed is removed by natural diffusion or natural convection only. Law. That is, the chemical filter of the present invention can be used by any of the ventilation method and the stationary method. As the ventilation method, for example, a unit in which a ventilation fan (for example, a device that takes in air, a device that discharges air, and the like) and the chemical filter of the present invention may be referred to as a “fan filter unit (FFU)” A) is used. Further, the FFU can be mounted on a ceiling or a clean booth, or provided in the middle of a duct.

(Use environment of the chemical filter of the present invention)
The chemical filter of the present invention can be used in various environments where the chemical filter can be used. For example, the chemical filter of the present invention can be used under a high-temperature environment where activated carbon cannot be used, under various concentration environments, under a humidity environment, and the like.

  The chemical filter of the present invention can be used in a wide temperature environment (for example, in an environment of 0 to 500 ° C.). A chemical filter using activated carbon as an adsorbent cannot be used because the activated carbon is gradually oxidized in a high-temperature environment, activation is advanced and pores are widened, and the removal performance is reduced. In addition, an adsorbent using an organic substance such as a resin cannot be used in a high-temperature environment because the resin melts or ignites in a high-temperature environment or deteriorates in an environment exceeding 40 ° C. On the other hand, the chemical filter of the present invention does not require the use of activated carbon as an adsorbent, and can be used in a wide temperature environment including a high temperature environment. The temperature of the environment in which the chemical filter of the present invention is used is not particularly limited, but is preferably from 10 to 300 ° C, more preferably from 15 to 100 ° C, and still more preferably from 15 to 50 ° C.

  Further, in a chemical filter using activated carbon as an adsorbent, it is presumed that the molecular movement of the siloxane compound is activated in a high-temperature environment, but the removal efficiency of the siloxane compound tends to decrease. On the other hand, since the adsorbent of the present invention mainly removes the siloxane compound by chemical adsorption, the siloxane compound can be efficiently removed even in a high-temperature environment.

  The chemical filter of the present invention can be used in a wide range of humidity environments (for example, in an environment of a relative humidity of 0 to 99% RH) within a range where no condensation occurs. For this reason, the chemical filter of the present invention can also efficiently remove siloxane compounds in dry air. The relative humidity at which the chemical filter of the present invention is used is not particularly limited, but is preferably 10 to 95% RH, more preferably 30 to 90% RH, and still more preferably 35 to 70% RH.

  In addition, when zeolite having a pH of 7 or less is used as the inorganic silica-based porous material having a pH of 7 or less in the water mixture, the amount of hydrogen ions in the zeolite is large, and the amount of other cations is relatively small. Is relatively high in hydrophobicity, so it is difficult to adsorb moisture in the fluid even in a high humidity environment, and is not easily affected by humidity. Therefore, the siloxane compound can be efficiently removed even in a high humidity environment.

The chemical filter of the present invention can be used in a wide range of pressure environments (for example, in an environment of 10 ^{-11 to} 100 MPa). Chemical filters using activated carbon as an adsorbent have a high removal efficiency in a high-pressure environment due to a high concentration of the substance to be removed, but when returning to normal pressure, substances that have excessively adhered due to pressure will be removed. Tends to detach. On the other hand, the chemical filter of the present invention firmly adsorbs and removes the siloxane compound, and therefore does not desorb even when used under a high-pressure environment and returned to normal pressure. For this reason, the chemical filter of the present invention can be used under a wide pressure environment including a high pressure environment. The pressure of the environment in which the chemical filter of the present invention is used is not particularly limited, but is preferably 10 ^{−7 to 1} MPa, more preferably 10 ^{−4 to 1} MPa, and still more preferably 0.05 to 1 MPa. Therefore, the chemical filter of the present invention can be preferably used even in a pressure pipe.

  The chemical filter of the present invention can be preferably used even under a wide range of siloxane compound concentration environments (for example, 0.001 ppb to 10 ppm). Further, the chemical filter of the present invention can remove the siloxane compound with high efficiency even in an environment where the concentration of the siloxane compound in the fluid is extremely low (for example, 1 digit ppb or less). In particular, the chemical filter of the present invention is preferably used in a very low-concentration environment in which the concentration of a siloxane compound in a fluid (particularly in the air) is 100 ppb or less (preferably 50 ppb or less, more preferably 10 ppb or less). Can be. Although not particularly limited, the concentration of the siloxane compound in the fluid is preferably 0.001 ppb or more.

  In addition, when using the chemical filter of the present invention in an environment where the concentration of the siloxane compound in the fluid is extremely low, the temperature of the environment is not particularly limited, but is preferably 0 to 500 ° C, more preferably 15 to 50 ° C. It is.

  The chemical filter of the present invention can be used under various wind speed environments (for example, the filtered wind speed is 0 to 5 m / s). In particular, it can be used under a high wind speed environment (for example, under an environment where the filtration wind speed is 1 to 5 m / s). In a chemical filter using activated carbon as an adsorbent, the removal efficiency tends to decrease as the wind speed of the passing air increases. On the other hand, the chemical filter of the present invention can efficiently remove a siloxane compound even under a high wind speed environment. The wind speed of the environment where the chemical filter of the present invention is used is not particularly limited, but the filtering wind speed is preferably 0 to 5 m / s, more preferably the filtering wind speed is 0 to 3 m / s, and further preferably the filtering wind speed is 0 to 0 m / s. 1 m / s.

  Further, the chemical filter of the present invention can be used even in an environment where the content of gas other than the siloxane compound is low (low gas environment) and in an environment where the concentration of air is low (for example, in a vacuum environment). it can. Further, the chemical filter of the present invention does not require the use of activated carbon as an adsorbent, and thus can be preferably used in an environment where flame retardancy is required.

  The chemical filter of the present invention is a chemical filter for removing a siloxane compound. The siloxane compound is a compound having at least a Si-O-Si skeleton in a molecule. Examples of the siloxane compound include cyclic siloxane compounds (for example, D3-D20 cyclic siloxane compounds such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane), and linear siloxane compounds (for example, Linear siloxane compounds having 2 to 20 silicon atoms, such as hexamethyldisiloxane, octamethyltrisiloxane, and decamethyltetrasiloxane), and branched siloxane compounds. Among them, a cyclic siloxane compound and a linear siloxane compound are preferable. The siloxane compound is preferably one having volatility.

  The chemical filter of the present invention uses an inorganic silica-based porous material in which the pH of a water mixture is 7 or less as an adsorbent. Thereby, in the chemical filter of the present invention, since the inorganic silica-based porous material acting as a solid acid has a silanol group (—Si—OH), the siloxane compound is hydrolyzed by the solid acid, and the silanol is added to the compound. It is presumed that a group is formed. As a result, the silanol groups (-Si-OH) in the inorganic silica-based porous material and the silanol groups generated by hydrolysis of the siloxane compound in the fluid (particularly in the air) are dehydrated and condensed. It is presumed that this is due to the formation of a Si-O-Si bond, but the siloxane compound is strongly adsorbed and removed mainly by chemical adsorption, and the siloxane compound once adsorbed is hard to be desorbed. Further, the bond between the inorganic silica-based porous material and the adsorbed siloxane compound has a remarkably strong bonding force as compared with the case where activated carbon is used.

  As described above, the chemical filter of the present invention removes a siloxane compound by using an inorganic silica-based porous material having a pH of a water mixture of 7 or less as an adsorbent. Therefore, unlike the case where an adsorbent such as activated carbon is used, the siloxane compound once adsorbed is not desorbed. Therefore, the adsorption capacity is easier to estimate than the chemical filter using activated carbon as the adsorbent, and the life analysis is relatively easy. Further, as described above, it is difficult to be detached even when the pressure is returned from the high pressure to the normal pressure, and therefore, it is also useful for pressure piping.

  Further, Patent Documents 2 to 5 disclose that a cyclic siloxane compound is removed using a resin or a porous material into which an acidic functional group is introduced. However, the sulfonic acid as the acidic functional group is a protonic acid, and has completely different properties from solid acids in inorganic silica-based porous materials such as zeolite. The same applies to the removal of the siloxane compound. In Patent Documents 2 to 5, the acidic functional group has a role of causing siloxane compounds to react with each other. On the other hand, in the present invention, as described above, the silanol group (—Si—OH) in the inorganic silica-based porous material is adsorbed by dehydration condensation of the silanol group generated by hydrolysis of the siloxane compound. ing. Thus, the adsorption mechanism of the porous material into which the acidic functional group is introduced is completely different from that of the adsorbent of the present invention. When the chemical filter of the present invention is used, since the reaction between the siloxane compounds is not required, the siloxane compound is efficiently removed even in an environment where the concentration of the siloxane compound in the fluid is extremely low. be able to.

  In Patent Documents 2 to 5, a resin or a porous material into which an acidic functional group is introduced is used. For this reason, in Patent Documents 2 to 5, a step of introducing an acidic functional group is essential when producing a chemical filter. In particular, the process for producing the acidic compound used in Patent Documents 3 and 4 is extremely complicated. On the other hand, it is not necessary to use a resin or a porous material into which an acidic functional group is introduced as the adsorbent of the present invention. For this reason, the chemical filter of the present invention does not need to provide a step of attaching an acidic compound to a resin or a porous material and a step of producing an acidic compound, and can be easily manufactured.

  Further, in a chemical filter using activated carbon as an adsorbent, when other gas components such as an organic gas component exist in addition to the siloxane compound in the fluid, the removal of the siloxane compound competes with the removal of the organic gas component. For this reason, the removal efficiency of the siloxane compound decreases. On the other hand, as described above, the adsorbent of the present invention mainly removes the siloxane compound by the silanol group in the inorganic silica-based porous material, so that the adsorbent does not compete with the removal of the organic gas component. Compounds can be selectively and efficiently removed.

[Fluid purification method]
Furthermore, the fluid can be purified by removing the siloxane compound in the fluid using the chemical filter of the present invention. As described above, a method of purifying a fluid by removing a siloxane compound in a fluid using the chemical filter of the present invention may be referred to as a “fluid purification method of the present invention”. For this reason, the chemical filter of the present invention can be used at an appropriate place to remove a siloxane compound in a fluid (for example, in air). For example, the chemical filter of the present invention is required to remove siloxane compounds, such as chemical filters in buildings such as ordinary households and clean rooms, chemical filters in construction sites, chemical filters in sewage treatment plants, and chemical filters in landfills. It can be particularly preferably used for certain applications. As the chemical filter in the clean room, a chemical filter around a semiconductor manufacturing process such as an internal chemical filter of an exposure apparatus, an inside chemical filter of a coating and developing apparatus, and a chemical filter around a cutting process of a semiconductor chip is particularly preferable.

  In the clean room (for example, a clean room in which gaseous pollutants are controlled, particularly a clean room in a semiconductor manufacturing plant), various gaseous organic compounds such as siloxane compounds are present. The siloxane compound is adsorbed on the surface of a semiconductor silicon wafer or the surface of a liquid crystal glass substrate, and may cause problems in these products. In the sewage treatment plant, the digestion gas generated from the digestion tank contains a trace amount of a siloxane compound derived from silicone oil contained in shampoos and cosmetics. Furthermore, in the above-mentioned landfill, a siloxane compound or a silanol compound contained in biogas in mud (eg, activated sludge) used for landfill may be a problem. Therefore, the chemical filter of the present invention can be particularly preferably used for air purification in such applications.

  Further, it can be preferably used for applications in which it is required to avoid poisoning by siloxane compounds such as gas sensors and reaction catalysts. In addition, it can also be used in the vicinity of various analyzers, gas supply lines, around where cell regeneration processing is performed, around where fine pore processing is performed, and at nuclear power plants. Further, since the siloxane compound may reduce the electromotive force of the fuel cell, it can be preferably used in the production process of the fuel cell and the like. Further, the siloxane compound may be deposited on a gas turbine, a boiler burner, a heat exchanger, or the like, thereby lowering the efficiency or causing a malfunction or a failure. .

  When the chemical filter of the present invention can selectively remove a siloxane compound, it is particularly preferable to use the chemical filter of the present invention for a gas sensor among the above. In general households and the like, gas sensors are used as sensors (detectors) for detecting propane and butane. In such a gas sensor, it is known that when a siloxane compound adheres to the surface of the detection unit, the sensitivity of the sensor is reduced and the detection performance is affected. In order to protect the sensor from the siloxane compound, the gas sensor is provided with a filter for adsorbing the siloxane compound. Activated carbon is generally used as an adsorbent in the above-mentioned filter, but a filter using such an adsorbent adsorbs even a gas that needs to be detected by a gas sensor such as propane or butane. Therefore, the gas sensor may be difficult to operate. In contrast, the above-described chemical filter of the present invention can selectively and efficiently remove a siloxane compound. For this reason, it is particularly preferable that the chemical filter of the present invention is used as a gas sensor (preferably, a filter installed in a gas sensor on the upstream side of a detector).

  When the chemical filter of the present invention is a chemical filter for a gas sensor, the chemical filter of the present invention can be used in a place where a gas sensor can be used, for example, a general household, a canteen, a kitchen, and the like, a hydrocarbon gas such as propane and butane. Can be used where possible. More specifically, it is preferable that the chemical filter of the present invention be provided immediately before the gas detection unit of the gas sensor. Other examples include a stationary method in which the chemical filter of the present invention is installed in the space where the gas sensor is installed, and the siloxane compound to be removed is removed by contact only with natural diffusion or natural convection.

[Gas sensor]
The chemical filter of the present invention can be used as a gas sensor by using the inside of the gas sensor. A gas sensor provided with the chemical filter of the present invention may be referred to as “gas sensor of the present invention”. The gas sensor of the present invention includes therein the chemical filter of the present invention. In particular, it is preferable that the gas sensor of the present invention is provided immediately before the gas detector. According to the gas sensor of the present invention, the chemical filter of the present invention using the inorganic silica-based porous material having a pH of the water mixture of 7 or less as the adsorbent is used as the internal chemical filter. The siloxane compound in the air can be removed more efficiently than a conventional gas sensor using a gas sensor chemical filter. In particular, the removal efficiency of the siloxane compound does not decrease in a short time, and the siloxane compound is not desorbed unlike activated carbon. For this reason, a decrease in the gas detection function of the gas sensor due to the siloxane compound in the air can be significantly suppressed. In addition, the adsorption of hydrocarbon gas such as propane and butane is low, and does not hinder the operation of the gas sensor. Furthermore, since the siloxane compound does not desorb from the adsorbent and lower the sensitivity of the sensor in the gas sensor, the failure of the sensor due to the siloxane compound in the air can be significantly suppressed.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto. Note that “ppb” is based on weight unless otherwise specified.

Example 1
The gas removal efficiency of the adsorbent was measured using an aeration test apparatus as shown in FIG. In Example 1, six series of two acrylic cylindrical test columns (inner diameter 50 mm, length 30 cm) 1 connected in series were arranged in parallel, and a gas supply tube 2 was provided upstream of the column. And a flow meter 3, a flow control valve 4, and a pump 5 were mounted in this order on the downstream side of the column. A non-woven fabric 6 is sandwiched between two columns connected in series, a test sample (adsorbent) 7 is laid on the non-woven fabric 6 with a thickness of 5 mm, and the flow rate is adjusted so that the filtration speed of the test sample is 5 cm / s. Air was blown. The air flowing through the column was prepared by mixing 200 ppb of octamethylcyclotetrasiloxane with air adjusted to a temperature of 23 ° C. and a humidity of 50% using a thermo-hygrostat. FIG. 2 shows a schematic cross-sectional view (for one series) of the aeration test apparatus.
As test samples (adsorbents), a plurality of zeolites having different pHs of the water mixture (content ratio: 5 wt%) shown in Table 1 and a plurality of zeolites having different pHs of the water mixture (content ratio: 5 wt%) shown in Table 2 Silica gel, acid clay, activated clay and diatomaceous earth were used. The removal efficiency was measured for each of the six test samples, and the six test samples to be measured were used for each column 1 arranged in six series in parallel. Natural zeolite B is a natural zeolite A treated with citric acid. Silica gel D is a silica gel A treated with hydrochloric acid.
On the third day after the start of the aeration test, air on the upstream and downstream sides of the column was collected by an adsorption tube, and the adsorption tube on which the air was collected was subjected to gas analysis by ATD (heat desorption apparatus) -GC / MS. And the gas concentration of octamethylcyclotetrasiloxane were measured. Calculate the removal efficiency of octamethylcyclotetrasiloxane from the measured gas concentrations of octamethylcyclotetrasiloxane on the upstream and downstream sides of the column using the following formula, and create a graph of the relationship between the pH of the water mixture of the test sample and the removal efficiency. did.
Removal efficiency (%) = {(gas concentration on upstream side−gas concentration on downstream side) / gas concentration on upstream side} × 100
The results are shown in Tables 1 and 2, FIG. 3 (zeolite), and FIG. 4 (silica gel, acid clay, diatomaceous earth). In FIG. 4, squares (□) indicate data for silica gel, triangles (三角) indicate data for acid clay, circles (○) indicate data for activated clay, and crosses (×) indicate data for diatomaceous earth. The horizontal axis of the graph is the pH of the water mixture of the test sample, and the vertical axis is the removal efficiency (%).

[Measurement of loss on ignition]
The ignition loss (%) in Table 2 was determined by the following method.
First, a sample (inorganic silica-based porous material) to be evaluated was spread thinly on a petri dish and allowed to stand in a thermo-hygrostat for one day, and the mass of the sample was measured and defined as “sample mass”. The thermogravimetric measurement (TG) of the inorganic silica-based porous material that was allowed to stand for one day using a differential thermal / thermogravimetric simultaneous measurement device (trade name “TG / DTA 6200”, manufactured by Hitachi High-Tech Science Corp.) , The mass after holding at 170 ° C for 2 hours and the mass after holding at 1000 ° C for 2 hours were measured. The mass after holding at 170 ° C. for 2 hours was referred to as “sample mass after drying”, and the mass after holding at 1000 ° C. for 2 hours was referred to as “sample mass after ignition”.
Then, the ignition loss was calculated from the above formula (1) using the obtained sample mass after drying and the sample mass after ignition. Table 3 shows the results of the sample mass after drying, the sample mass after ignition, and the loss on ignition.

  As shown in Table 1, Table 2, FIG. 3, and FIG. 4, inorganic silica-based porous materials such as zeolite, silica gel, activated clay, and diatomaceous earth having a pH of the water mixture of 7 or less have a pH of the water mixture of 7 or less. The removal efficiency of octamethylcyclotetrasiloxane is remarkably higher than that of the inorganic silica-based porous material exceeding the above.

Comparative Example 1
Except that an acidic ion exchange resin (containing a sulfonic acid group) was used as a test sample (adsorbent), gas removal of the adsorbent was performed using a gas permeability test apparatus as shown in FIG. 1 in the same manner as in Example 1. The efficiency was measured.
On the third day after the start of the aeration test, air on the upstream and downstream sides of the column was collected by an adsorption tube, and the adsorption tube on which the air was collected was subjected to gas analysis by ATD (heat desorption apparatus) -GC / MS. The gas concentration of octamethylcyclotetrasiloxane was measured. From the measured gas concentrations of octamethylcyclotetrasiloxane on the upstream and downstream sides of the column, the removal efficiency of octamethylcyclotetrasiloxane was calculated by the following equation.
Removal efficiency (%) = {(gas concentration on upstream side−gas concentration on downstream side) / gas concentration on upstream side} × 100
As a result, the removal efficiency of octamethylcyclotetrasiloxane when using the acidic ion exchange resin was 0%.

Example 2
An extraction test with acetone was performed on a portion of the test samples after the end of the ventilation test of Example 1. Some of the test samples described above were placed in 30 ml of acetone solvent and shaken for 2 hours. Thereafter, the supernatant was subjected to GC-FID analysis. Table 4 shows the area value of octamethylcyclotetrasiloxane measured by GC-FID. For comparison, coconut shell activated carbon (manufactured by Futamura Chemical Co., Ltd., trade name "Taiko CB", pH of a water mixture: 10.17), and acid-impregnated activated carbon (potassium hydrogen sulfate was impregnated on the coconut shell activated carbon) , Impregnated amount of impregnating agent with respect to activated carbon: 6% by weight, pH of water mixture: 2.61), activated carbon activated by chemicals (Futamura Chemical Co., Ltd., trade name "Taiko S", pH of water mixture: 4.48) ) Was used as an adsorbent, and a gas permeability test was performed in the same manner as in Example 1. The area value of octamethylcyclotetrasiloxane measured by GC-FID in the same manner as in the above test sample is shown in Table 4. The area values shown in Table 4 are numerical values when the area value of the coconut shell activated carbon is 100 (in terms of volume).

  As shown in Table 4, in the case of coconut shell activated carbon, acid-impregnated activated carbon, and chemical activated activated carbon, the adsorbed octamethylcyclotetrasiloxane is desorbed by acetone extraction, but the pH of the water mixture is 7 or less, In the case of an inorganic silica-based porous material such as silica gel, activated clay, and diatomaceous earth, the adsorbed octamethylcyclotetrasiloxane is not desorbed by acetone extraction. This indicates that octamethylcyclotetrasiloxane is adsorbed on the inorganic silica-based porous material whose pH of the water mixture is 7 or less with an extremely strong force as compared with activated carbon.

Example 3
Gel permeation chromatography analysis was performed on each of the test samples (zeolite D, zeolite I, silica gel B, activated clay A, and diatomaceous earth A) after the end of the aeration test of Example 1. 0.5 g of the above test sample and 1 g of tetrahydrofuran (THF) were mixed and eluted, filtered, and then the molecular weight was measured by gel permeation chromatography. That is, a column with a filler (showdex KE-806M 804 802, manufactured by Showa Denko KK) was attached to a molecular weight measuring device (CO-8020 UV-8020 RI-9202 DP-8020, manufactured by Tosoh Corporation), The measurement was performed at 1.0 mL / min at a column temperature of 40 ° C. by using THF (THF without a stabilizer, manufactured by Wako Pure Chemical Industries, Ltd.) as an eluate. As a result, a peak having a weight-average molecular weight of several hundreds was detected, but a peak having a larger weight-average molecular weight of several hundred thousand was not detected.
From these results, the adsorbent of the present invention does not polymerize and adsorb the siloxane compound as in the inventions described in Patent Documents 2 and 5, but directly reacts the inorganic silica-based porous material with the siloxane compound. You can see that it has been removed.

Example 4
The same procedure as in Example 1 was carried out except that air which was adjusted to a temperature of 23 ° C. and a humidity of 50% using a constant temperature and humidity chamber and mixed with 60 ppb of decamethyltetrasiloxane was used as the air flowing through the column. The gas removal efficiency of the adsorbent was measured using an aeration test apparatus as shown in FIG. Note that, as a test sample (adsorbent), a plurality of zeolites and diatomaceous earths having different pHs of water mixtures (content ratio: 5 wt%) shown in Table 5 were used.
On the third day after the start of the aeration test, air on the upstream and downstream sides of the column was collected by an adsorption tube, and the adsorption tube on which the air was collected was subjected to gas analysis by ATD (heat desorption apparatus) -GC / MS. And the gas concentration of decamethyltetrasiloxane were measured. The decamethyltetrasiloxane removal efficiency was calculated from the measured gas concentrations of decamethyltetrasiloxane on the upstream and downstream sides of the column by the following formula, and a graph of the relationship between the pH of the water mixture of the test sample and the removal efficiency was created.
Removal efficiency (%) = {(gas concentration on upstream side−gas concentration on downstream side) / gas concentration on upstream side} × 100
The results are shown in Table 5 and FIG. In FIG. 5, rhombus (ゼ) indicates zeolite data, and cross (x) indicates diatomaceous earth data. The horizontal axis of the graph is the pH of the water mixture of the test sample, and the vertical axis is the removal efficiency (%).

  As shown in Table 5 and FIG. 5, the pH of the water mixture is 7 or less, and the inorganic silica-based porous material such as diatomaceous earth has a pH of the water mixture of more than 7 compared to the inorganic silica-based porous material. The removal efficiency of decamethyltetrasiloxane is remarkably large.

Example 5
The same procedure as in Example 1 was carried out except that air which was adjusted to a temperature of 23 ° C. and a humidity of 50% using a constant temperature and humidity chamber and mixed with 100 ppb of n-hexane and 100 ppb of toluene was used as the air flowing through the column. The gas removal efficiency of the adsorbent was measured using an aeration test apparatus as shown in FIG. In addition, as the test sample (adsorbent), a plurality of inorganic silica-based porous materials having different pH values of the water mixture (content ratio: 5 wt%) shown in Table 6 were used.
On the third day after the start of the aeration test, air on the upstream and downstream sides of the column was collected by an adsorption tube, and the adsorption tube on which the air was collected was subjected to gas analysis by ATD (heat desorption apparatus) -GC / MS. , N-hexane and toluene were measured. The removal efficiency of each gas component was calculated from the gas concentrations of n-hexane and toluene on the upstream and downstream sides of the measured column by the following formula, and a graph of the relationship between the pH of the water mixture of the test sample and the removal efficiency was created. .
Removal efficiency (%) = {(gas concentration on upstream side−gas concentration on downstream side) / gas concentration on upstream side} × 100
Table 6 shows the results.

  As shown in Table 6, when an inorganic silica-based porous material having a pH of the water mixture of 7 or less was used, the efficiency of removing organic compounds such as n-hexane and toluene was relatively low. Therefore, the siloxane compound can be selectively removed.

Example 6
(Manufacture of chemical filter with sheet packaging structure)
100 parts by weight of the olefinic thermoplastic resin was placed in a metal container placed on a hot plate set at 150 ° C., and the adsorbent was added little by little while stirring the resin in the container. After all the adsorbents were put in the container, stirring was continued for about 5 minutes to obtain a resin composition in which the resin and the adsorbent were uniformly mixed (kneaded). Then, the obtained resin composition was thinly stretched on a Petri dish of Φ65 mm so that the weight of the resin became 5 g, to form a sheet. In addition, three kinds of sheets were produced using diatomaceous earth A (100 parts by weight), synthetic zeolite I (100 parts by weight), and silica gel B (20 parts by weight) as the adsorbent.

(Adsorption amount evaluation)
Without removing the three types of sheets obtained above from the petri dish, the three petri dishes and the petri dish containing 1.5 g of octamethylcyclotetrasiloxane were placed in a single metal closed container, and placed under an environment of 23 ° C. It was left still for 3 days. The weight of the petri dish before and after standing was measured, and the difference was defined as the adsorption amount of octamethylcyclotetrasiloxane. The results are shown below.
Diatomaceous earth A: 0.072 g
Synthetic zeolite I: 0.067 g
Silica gel B: 0.091 g

  The chemical filter of the present invention can be used at an appropriate place to remove a siloxane compound in a fluid (for example, in air). For example, the chemical filter of the present invention is required to remove siloxane compounds, such as chemical filters in buildings such as ordinary households and clean rooms, chemical filters in building sites, chemical filters in sewage treatment plants, and chemical filters in landfills. It can be particularly preferably used for certain applications. As the chemical filter in the clean room, a chemical filter around a semiconductor manufacturing process such as an internal chemical filter of an exposure apparatus, an inside chemical filter of a coating and developing apparatus, and a chemical filter around a cutting process of a semiconductor chip is particularly preferable.

DESCRIPTION OF SYMBOLS 1 Column 2 Tube 3 Flow meter 4 Flow control valve 5 Pump 6 Nonwoven fabric 7 Test sample (adsorbent)

Claims (14)

An inorganic silica-based porous material in which the pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water is 7 or less,
When the inorganic silica-based porous material is zeolite, at least one selected from the group consisting of ferrierite, MCM-22, ZSM-5, ZSM-11, beta type, X type, Y type, and offretite the proton-type zeolite having a skeleton structure,
When the inorganic silica-based porous material is other than zeolite, it is one or more selected from the group consisting of diatomaceous earth, silica gel, and activated clay, and has a loss on ignition of 2.5 determined by the following formula (1). Using an inorganic silica-based porous material of up to 7.0% as an adsorbent;
A chemical filter for removing siloxane compounds, which adsorbs siloxane compounds by chemical adsorption.
Loss on ignition I (%) = (W ₁ −W ₂ ) / W ₁ × 100 (1)
W ₁ : Mass of sample after drying W ₂ : Mass of sample after ignition [In formula (1), mass of sample after drying (W ₁ ) is obtained by using an inorganic silica-based porous material at about 170 ° C. in air or vacuum. This is the mass of the inorganic silica-based porous material after heating at about 150 ° C. for 2 hours.
The sample mass after ignition (W ₂ ) is the mass of the inorganic silica-based porous material obtained by igniting the dried inorganic silica-based porous material at 1000 ° C. ± 50 ° C. for 2 hours. . ] Examples adsorbent, the water mixture (content: 5 wt%) with inorganic silica-based porous material a pH of 7 or less, the siloxane compound removal chemical filter of claim 1 with other adsorbents. The inorganic silica-based porous materials, synthetic zeolites, diatomaceous earth, silica gel, and one or more selected from the group consisting of activated clay, claim 1 or 2 containing 10% by weight or more based on the total weight of the adsorbent Chemical filter for removing a siloxane compound according to the above. The synthetic zeolite is included as the inorganic silica-based porous material, and a ratio (molar ratio) of SiO ₂ to Al ₂ O ₃ [SiO ₂ / Al ₂ O ₃ ] in the synthetic zeolite is 4 to 2,000 . 4. The chemical filter for removing a siloxane compound according to any one of 3 . The chemical filter for removing a siloxane compound according to any one of claims 1 to 4 , wherein the inorganic silica-based porous material includes a synthetic zeolite having 10 to 12 ring members. The chemical filter for removing a siloxane compound according to any one of claims 1 to 5 , wherein the inorganic silica-based porous material includes a synthetic zeolite having a two- or three-dimensional pore connection. The chemical filter for removing a siloxane compound according to any one of claims 1 to 6 , wherein the chemical filter has the adsorbent attached to a filter substrate by a binder. A chemical filter for removing siloxane compounds in which an adsorbent is attached to a filter substrate by a binder,
When the adsorbent is an inorganic silica-based porous material having a pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water of 7 or less, and the inorganic silica-based porous material is zeolite Adsorbs a proton-type zeolite, and an inorganic silica-based porous material having a loss on ignition determined from the following formula (1) of 2.5 to 7.0% when the inorganic silica-based porous material is other than zeolite. Used as an agent,
The binder, water mixture obtained by mixing with pure water (content: 5 wt%) Ri binder der pH of 7 or less,
A chemical filter for removing a siloxane compound , wherein the adsorbent adsorbs the siloxane compound by chemical adsorption .
Loss on ignition I (%) = (W ₁ −W ₂ ) / W ₁ × 100 (1)
W ₁ : Mass of sample after drying
W ₂ : mass of sample after ignition
[In formula (1), the sample mass after drying (W ₁ ) is the inorganic silica-based porous material obtained by heating the inorganic silica-based porous material at about 170 ° C. in air or at about 150 ° C. under vacuum for 2 hours. Is the mass of
The sample mass after ignition (W ₂ ) is the mass of the inorganic silica-based porous material obtained by igniting the dried inorganic silica-based porous material at 1000 ° C. ± 50 ° C. for 2 hours. . ] 9. The chemical filter for removing a siloxane compound according to claim 7 , wherein the binder is colloidal inorganic oxide particles. Structure of the chemical filter is a honeycomb structure, pleated structures, three-dimensional network structure, the sheet package structure, and any one of the preceding claims having at least one structure selected from the group consisting of a sheet-like structure Chemical filter for removing a siloxane compound according to the above. The chemical filter for removing a siloxane compound according to any one of claims 1 to 6 , wherein the chemical filter for removing a siloxane compound includes the pelletized adsorbent. It is a chemical filter for removing siloxane compounds containing a pelletized adsorbent,
When the adsorbent is an inorganic silica-based porous material having a pH of a water mixture (content ratio: 5 wt%) obtained by mixing with pure water of 7 or less, and the inorganic silica-based porous material is zeolite Adsorbs a proton-type zeolite, and an inorganic silica-based porous material having a loss on ignition determined from the following formula (1) of 2.5 to 7.0% when the inorganic silica-based porous material is other than zeolite. Used as an agent,
The pelletization water mixture obtained by mixing with pure water (content: 5 wt%) have use the binder is pH of 7 or less,
A chemical filter for removing a siloxane compound , wherein the adsorbent adsorbs the siloxane compound by chemical adsorption .
Loss on ignition I (%) = (W ₁ −W ₂ ) / W ₁ × 100 (1)
W ₁ : Mass of sample after drying
W ₂ : mass of sample after ignition
[In formula (1), the sample mass after drying (W ₁ ) is the inorganic silica-based porous material obtained by heating the inorganic silica-based porous material at about 170 ° C. in air or at about 150 ° C. under vacuum for 2 hours. Is the mass of
The sample mass after ignition (W ₂ ) is the mass of the inorganic silica-based porous material obtained by igniting the dried inorganic silica-based porous material at 1000 ° C. ± 50 ° C. for 2 hours. . ] The chemical filter for removing a siloxane compound according to any one of claims 1 to 6 , wherein the chemical filter for removing a siloxane compound has the adsorbent attached to a filter substrate without using a binder. A resin composition used for the chemical filter for removing a siloxane compound according to any one of claims 1 to 6 , wherein the resin composition contains the inorganic silica-based porous material and a resin.

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