Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/14—Other self-supporting filtering material ; Other filtering material
  • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
  • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
  • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/14—Other self-supporting filtering material ; Other filtering material
  • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
  • B01D46/0002—Casings; Housings; Frame constructions
  • B01D46/0005—Mounting of filtering elements within casings, housings or frames
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/04—Additives and treatments of the filtering material
  • B01D2239/0407—Additives and treatments of the filtering material comprising particulate additives, e.g. adsorbents

Definitions

• Fig. 1 depicts a portion of an exemplary air filter comprising a filter support comprising sorbent particles as disclosed herein.
• Fig. 6 depicts an exemplary respirator comprising a filter support comprising sorbent particles as disclosed herein.
• fibrous web refers to a filter support that is comprised of numerous layers (e.g., more than five) of fibers.
• the moving air may flow at least generally perpendicular to a major surface of the support (e.g., as in the arrangement of Fig. 2). In some embodiments, moving air may flow in directions intermediate between these two extremes. In some embodiments, airflow in both directions and/or in directions intermediate between these two extremes, may occur e.g. in different portions of the air filter.
• an air filter 1 may comprise a filter support 10 that is in the form of a "honeycomb" 15.
• honeycomb a flow-through support structure that comprises numerous macroscopic through- apertures that allow airflow therethrough, the apertures being separated from each other by partitions (walls) of the honeycomb structure.
• partitions walls
• honeycomb the term honeycomb is used here for convenience, the skilled person will appreciate that the structure may be of any geometry (e.g., with apertures that are square, triangular, round, etc.) and may exhibit a somewhat irregular appearance rather than being limited strictly to the regular hexagonal geometry shown in the exemplary design of Fig. 3).
• the sorbent particles may be packed loosely within the apertures e.g. so that the particles are able to move or shift slightly.
• the sorbent particles may be bonded to each other (e.g., by use of an adhesive, a heat-activated binder, etc., in amounts sufficient to bond particles to each other at contact points but not in amounts that would unacceptably occlude the particles so as to impact their ability to capture gaseous substances) e.g. so as to minimize shifting or settling of the particles within the apertures.
• Exemplary nettings that might be suitable for use as disclosed herein include various products available from Delstar Technologies; for example, the products available under the trade designations KX215P, R0412-10PR, RB0404-10P, N02014-90PP, RB0404-28P, N03011-90PP, and TK16-SBSH.
• a filter support 10 may comprise a sheet-like material comprised of numerous fibers, often entangled with each other and often present in numerous "layers" (e.g., more than five layers) as shown in exemplary embodiment in Fig. 5.
• the term fibrous web will be used herein for convenience in describing any such material. It will be appreciated of course that due to the random nature of many such fibrous webs, the fibers may not necessarily be, and often will not be, present in discrete layers (e.g., layers that can be peeled apart from each other); however, it will be readily apparent if e.g.
• the nonwoven web may be a meltblown web, which process and resulting web will be well known to the skilled person. Any combination of layers of these various materials (including combination with layers that are not nonwoven webs) can be used.
• the fibers may be made of any suitable material, e.g. thermoplastic organic fibers (such as e.g. polyolefin fibers, cellulosic fibers, polyester fibers, nylon fibers, etc.), inorganic fibers (such as e.g. fiberglass or ceramic fibers), metal fibers, and so on.
• Such a particle filtration layer may be electrostatically charged if desired, and in various embodiments may exhibit a Percent Penetration of less than about 80, 70, 60, 50, 40, 30, 20, 10, or 5.
• the term particle broadly encompasses e.g. aerosols, dust, mist, fumes, smoke, mold, bacteria, spores, pollen, and so on.
• such a particle-filtration layer may be a high-loft spunbonded nonwoven web e.g. of the type described in U.S. Patent 8240484 to Fox, and comprising a solidity of from less than 8 %, to about 4 %, and that is comprised of meltspun fibers that are substantially free of crimped fibers, gap-formed fibers and bicomponent fibers.
• an air filter 1 comprising sorbent particles 100 as disclosed herein, may be used in combination with a secondary air filter that is provided separately from air filter 1.
• an air filter 1 and a secondary air filter may be separately installed into different areas of an air-handling apparatus.
• an air filter 1 and a secondary air filter may each be a framed air filter and may each be separately inserted e.g. into a room air purifier.
• an air filter 1 and a secondary air filter may be assembled together (and e.g. attached to each other) before being installed into e.g. an air-handling apparatus.
• Air filter 1 can be placed e.g.
• a filter support 10 comprising sorbent particles 100 as disclosed herein may be used in any kind of air filter 1, configured for any suitable end use.
• filter support 10 may find use in e.g. an air filter that is, or is part of, a personal respiratory protection device.
• filter support 10 may take the form of a filter cartridge that can be fluidly coupled to a mask body to provide a personal respiratory protection device (e.g., the filter cartridge being disposable and the mask body being a piece that is shaped to fit a user's face and that is retained and a replacement filter cartridge attached thereto at an appropriate time).
• filter support 10 may be incorporated into a "filtering face-piece" respirator mask 60.
• the above discussions relate to methods of providing polymeric sorbent particles 100 on a suitable filter support 10 to provide an air filter 1 and positioning the air filter so that the supported sorbent particles are exposed to air
• air is used broadly and encompasses any gas or gaseous mixture, e.g. nitrogen, dehumidified nitrogen or air, oxygen-enriched air, air including an anesthetic gas or gas mixture, and so on.
• the air to which the sorbent particles are exposed is in the form of a moving airstream.
• active active filtration
• such moving air may be motivated by a motorized blower, fan, and so on.
• an air filter 1 as disclosed herein encompasses such devices as e.g. a cartridge, bag, pouch, canister, or, in general, any kind of container that holds sorbent particles 100 therein and that has at least one air-permeable wall so as to allow air to enter the container and contact the sorbent particles and to then exit the container, regardless of whether such a device is or is not used with any kind of mechanical blower or is used in any kind of respirator.
• the precursor polymeric material contains monomeric units of Formula (II) in a range of 8 to 65 weight percent, 15 to 65 weight percent, 15 to 60 weight percent, 15 to 50 weight percent, 15 to 40 weight percent, 20 to 65 weight percent, 20 to 60 weight percent, 20 to 50 weight percent, 20 to 40 weight percent, 30 to 65 weight percent, 30 to 60 weight percent, 30 to 50 weight percent, 40 to 65 weight percent, or 40 to 60 weight percent. These amounts are based on the total weight of the monomeric units in the precursor polymeric material.
• the two groups attached to the benzene ring can be in an ortho, meta, or para arrangement to each other.
• the monomeric units of Formula (III) contribute to the high crosslink density and to the formation of a rigid polymeric material having micropores and/or mesopores.
• the amount of divinylbenzene used to form the precursor polymeric material can have a strong influence on the BET specific surface area of both the precursor polymeric material and the polymeric sorbent.
• the BET specific surface area tends to increase with an increase in the amount of divinylbenzene in the monomer mixture used to form the precursor polymeric material and with the resulting amount of monomeric units of Formula (III) in the polymeric sorbent. If the amount of divinylbenzene is less than 30 weight percent, the polymeric sorbent may not have a sufficiently high BET specific surface area.
• the organic solvent can function as a porogen during the formation of the precursor polymeric material.
• the organic solvent choice can strongly influence the BET specific surface area and the size of the pores formed in the precursor polymeric material. Using organic solvents that are miscible with both the monomers and the forming polymer tends to result in the formation of micropores and mesopores within the precursor polymeric material. Good solvents for the monomers and the forming polymer tend to result in a larger fraction of the porosity of the final polymeric sorbent being in the form of micropores and mesopores.
• the polymerizable compositions used to form the precursor polymeric material typically include an initiator for free radical polymerization reactions.
• Any suitable free radical initiator can be used. Suitable free radical initiators are typically selected to be miscible with the monomers included in the polymerizable composition.
• the free radical initiator is a thermal initiator that can be activated at a temperature above room temperature. In other embodiments, the free radical initiator is a redox initiator. Because the polymerization reaction is a free radical reaction, it is desirable to minimize the amount of oxygen in the polymerizable composition.
• the polymerizable composition is typically free or substantially free of surfactants.
• the term "substantially free" in reference to the surfactant means that no surfactant is purposefully added to the polymerizable composition and any surfactant that may be present is the result of being an impurity in one of the components of the polymerizable composition (e.g., an impurity in the organic solvent or in one of the monomers).
• the polymerizable composition typically contains less than 0.5 weight percent, less than 0.3 weight percent, less than 0.2 weight percent, less than 0.1 weight percent, less than 0.05 weight percent, or less than 0.01 weight percent surfactant based on the total weight of the polymerizable composition. The absence of a surfactant is advantageous because these materials tend to restrict access to and, in some cases, fill micropores and mesopores in a precursor polymeric material.
• This compound is guanidine when Ri is hydrogen.
• micrometers 100 mesh (>150 micrometers), 80 mesh (>180 micrometers), 60 mesh (>250 micrometers), 50 mesh (> 300 micrometers), or 45 mesh (>355 micrometers).
• the porosity of a polymeric sorbent can be characterized from an adsorption isotherm of an inert gas such as nitrogen or argon by the porous material under cryogenic conditions (e.g., liquid nitrogen at 77 °K).
• the adsorption isotherm is typically obtained by measuring adsorption of the inert gas such as argon by the porous polymeric sorbent at multiple relative pressures in a range of about 10 "6 to about 0.98 + 0.01.
• the isotherms are then analyzed using various methods such as the BET (Brunauer-Emmett- Teller) method to calculate specific surface area and such as Density Functional Theory (DFT) to characterize the porosity and the pore size distribution.
• BET Brunauer-Emmett- Teller
• the polymeric sorbent typically has a BET specific surface area equal to at least 25 m 2 /gram.
• the BET specific surface area is at least 50 m 2 /gram, at least 75 m 2 /gram, or at least 100 m 2 /gram.
• the BET specific surface area can be up to 700 m 2 /gram or higher, up to 600 m 2 /gram, up to 500 m 2 /gram, up to 400 m 2 /gram, up to 300 m 2 /gram, or up to 200 m 2 /gram.
• the change in color signals that the capacity of the polymeric sorbent for sorption of an aldehyde has been reached or is close to being reached.
• the term "close to being reached” means that at least 60 percent or more of the capacity has been reached (i.e., a least 60 percent or more of the available sorption sites have been used for sorption of an aldehyde). For example, at least 70 percent, at least 80 percent, at least 90 percent, or at least 95 percent of the sorption sites have been used for sorption of an aldehyde.
• the role of polymeric sorbent particles 100 may be at least partly, or primarily, to provide a visual indication that a gaseous aldehyde (e.g. formaldehyde) is present in the air to which the polymeric sorbent particles are exposed. That is, a collection of such polymeric sorbent particles 100, presented on a suitable filter support 10, might provide a similar function as, for example, the well-known gas detection devices of the type exemplified by Drager tubes.
• a gaseous aldehyde e.g. formaldehyde
• Embodiment 6 is the air filter of any of embodiments 1-5 wherein the air filter consists essentially of the filter support.
• Embodiment 7 is the air filter of any of embodiments 1-6 wherein the filter support comprises a sheet-like material that exhibits a major plane and that exhibits a thickness of less than about 3 mm and that is configured to allow airflow through the filter support at least in a direction at least generally perpendicular to the major plane of the sheet-like material.
• Embodiment 8 is the air filter of any of embodiments 1-3 and 6-7 wherein the filter support comprises a netting with a major surface with at least some polymeric sorbent particles adhesively attached thereto.
• This product (polymeric sorbent) had a BET specific surface area (SABET) in the range of approximately 140 m 2 /gram and a total pore volume in the range of approximately 0.17 cm 3 /gram (p/p° equal to 0.98).
• SABET BET specific surface area
• An air filter (sold for use with room air purifiers designated as model KJEA-400, available from 3M Company, Shanghai, China) was obtained.
• the filter as obtained comprised a honeycomb support filled with a sorbent that was believed to be an activated carbon and that appeared to be in the form of particles in the range of 6 x 12 mesh.
• a protective screen was removed from one major side of the honeycomb and the activated carbon was discarded (from each of the through-apertures of the honeycomb) and was replaced by a roughly equivalent volume of the above-described polymeric sorbent. (However, the total weight of polymeric sorbent used was only about 40 percent of the weight of the activated carbon that it replaced, due to the significantly lower density of the polymeric sorbent.)
• the protective screen was replaced to provide the Working Example A air filter.
• This product (polymeric sorbent) had a BET specific surface area (SABET) in the range of approximately 140 m 2 /gram and a total pore volume in the range of approximately 0.17 cmVgram (p/p° equal to 0.98).
• SABET BET specific surface area

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Filtering Materials (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Separation Of Gases By Adsorption (AREA)
• Electrostatic Separation (AREA)
• Respiratory Apparatuses And Protective Means (AREA)
• Disinfection, Sterilisation Or Deodorisation Of Air (AREA)

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Cited By (15)

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• 2017
  • 2017-03-10 WO PCT/US2017/021856 patent/WO2017160650A2/en active Application Filing
  • 2017-03-10 JP JP2018548346A patent/JP6956103B2/ja active Active
  • 2017-03-10 CN CN201780016760.3A patent/CN108778454B/zh active Active
  • 2017-03-10 KR KR1020187029383A patent/KR102395544B1/ko active IP Right Grant
  • 2017-03-13 TW TW106108180A patent/TWI727015B/zh active

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