TWM523071U - Framed, pleated air filter comprising pleated air filter media with three layers - Google Patents

Abstract

A framed, pleated air filter, including a pleated air filter media that includes a first, stiffening layer, a second, sorbent layer, and a third, protective layer.

Description

Frame pleated air filter including three layers of pleated air filter media

The present invention relates to an air filter, and more particularly to a frame pleated air filter.

Air filters, such as pleated air filters, are often used to remove impurities from the air.

In a wide range of creative content, a frame pleated air filter is disclosed herein, the frame pleated air filter comprising a pleated air filter medium comprising a first reinforcement layer and a second An adsorbent layer and a third protective layer. These and other aspects will be apparent from the detailed description which follows. However, in no event shall this extensive content be interpreted as limiting the claimed subject matter, whether in the scope of the patent application as filed in the original application or in the application process. Proposed in the scope of the patent application as amended or otherwise proposed.

2‧‧‧Frame pleated air filter

4‧‧‧Pleated air filter media

4a‧‧‧ first major surface

4b‧‧‧ second major surface

4c‧‧‧ peripheral edge area

6‧‧‧Support frame

6a‧‧‧Grid-like part

7‧‧‧ third protective layer

8‧‧‧First reinforcement

10‧‧‧Second adsorbent layer

12‧‧‧bonded fiber

14‧‧‧ adsorbent particles

71‧‧‧ side wall

101‧‧‧ unpleated strands

200‧‧‧Subframe

The present writing will be further described with reference to the accompanying drawings in which: Figure 1 is a perspective view of an exemplary frame pleated air filter having a frame in partial cross-section.

Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1.

Figure 3 is a detailed cross-sectional illustration of the air filter media in the air filter of Figure 1.

4 is a cross-sectional view of an exemplary pleated air filter media including exemplary unpleated strands.

Figure 5 presents experimental data for formaldehyde removal from a working example pleated air filter.

The same reference numbers are used in the various drawings. All figures and figures in this document are not to scale and are chosen to illustrate the purpose of the various embodiments of the present invention. In particular, the dimensions of the various components are only depicted in an illustrative manner, and the relationship between the dimensions of the various components should not be inferred from the drawings. Although in this disclosure, such as "top", "bottom", "upper", "lower", "under", "on", "front", "back", "outside" may be used. Terms of "internal", "upward" and "downward" and "first" and "second", but it should be understood that their terms are used in their relative meaning unless otherwise indicated. One of ordinary skill will appreciate that, as used herein, terms such as "substantially free" and the like do not exclude the presence of some very low amounts (e.g., 0.1% or less), for example, in large scale applications. Material may be present when the production equipment is subjected to customary cleaning procedures.

the term

The term "spunbond" means a nonwoven web comprising a plurality of melt spun fibers which are assembled into a mass of fibers and bonded to form a nonwoven web.

The term "melt spinning" refers to fibers formed by extruding filaments from a set of orifices and allowing the filaments to cool and solidify to form fibers, wherein the filaments pass through the air gap (which may A flow of air is included to help cool the filaments and pass through the draw length (ie, draw) unit to at least partially draw the filaments.

The term "meltblown" refers to fibers (and resulting webs) formed by extruding molten filaments into a concentrated high velocity air stream introduced through a gas vent located in the immediate vicinity of the extrusion orifice. The average technician will understand the fundamental difference between spunbond and meltblown webs and will It is further understood that melt-spun fibers and webs and meltblown fibers and webs will characteristically exhibit features and indicia that can identify and distinguish such fibers and webs (eg, differences in the molecular orientation of the materials that make up the fibers, such as, for example, Revealed by optical properties (such as birefringence), melting behavior, etc.).

Short fibers mean fibers that have been cut or chopped to a predetermined length. Such fibers will be readily distinguishable from, for example, meltblown fibers and webs as well as spunbond fibers and webs.

"Pleated" means a web that has been at least partially configured to form a column comprising substantially parallel, oppositely oriented folds (pleats). Thus, the overall pleating of the web is different from curling a single fiber.

Frame filter and media

1 and 2 show a frame type pleated air filter 2. The frame pleated air filter 2 includes a pleated air filter medium 4 and a support frame 6 having a first major surface 4a and a second major surface 4b opposite to each other and a peripheral edge region 4c, the support frame 6 is disposed around at least a peripheral edge region of the filter medium 4. As shown in FIG. 3, the filter medium 4 includes a first reinforcement layer 8, which is a first nonwoven web, and a second adsorbent layer 10, which includes adsorbent particles. The second of 14 is not woven. The filter medium 4 further comprises a third protective layer 7 which is a third nonwoven web on the side of the second adsorbent layer 10 opposite the first reinforcing layer 8. In some embodiments, the third layer 7 can be in direct contact with the second layer 10 and/or the first layer 8 can be in direct contact with the second layer 10 without the intervening layer. In other embodiments, one or more intervening layers may be present between layer 8 and layer 10 and/or between layer 7 and layer 10.

First reinforcement layer

The first reinforcement layer 8 can comprise any suitable first nonwoven web. In various embodiments, the first nonwoven web can be relatively rigid, for example to exhibit a Gurley Stiffness of at least about 200 mg, 300 mg, 400 mg, 500 mg, 700 mg, 800 mg, 900 mg, or 1000 mg. As discussed later, the presence of this highly rigid layer helps ensure empty The air filter media 4 is pleated. Suitable first nonwoven webs may include, for example, air flow webs, wet webs, card webs, and the like. In a particular embodiment, the first nonwoven web can be a spunbond web. Spunbonding webs can be made by methods well known to those skilled in the art, such as those disclosed in U.S. Patent No. 7,947, 142, the disclosure of which is incorporated herein by reference. One of ordinary skill will appreciate that the configuration of individual fibers and/or fibers in a spunbond web distinguishes spunbond webs from other types of webs (e.g., meltblown webs, carded webs, airlaid webs, wet webs, etc.). In other words, the spunbond web will be readily identifiable to the average technician based on the configuration of the fibers in the web and can be distinguished from other types of non-woven webs. (With a specific example, the spunbond web will comprise substantially continuous fibers, as opposed to short fibers such as those described below.) In other embodiments, the first nonwoven web can be a staple web. One of ordinary skill will recognize that staple fiber systems have been pre-formed and then have been cut to a predetermined length (and have been assembled into a web, such as by airlaying, carding, wet-laid, or the like). In some embodiments, the first nonwoven web may be selected from the group consisting of a spunbond web and a staple web.

The first nonwoven web can be made of any suitable fiber-forming polymer selected from, for example, polyolefins, polyesters, nylons, and the like. In one embodiment, the first nonwoven web may be formed from polypropylene. In various embodiments, the first nonwoven web can exhibit a basis weight of at least about 60, 80, 100, or 120 g/m ² . In further embodiments, the first nonwoven web can exhibit a basis weight of up to about 200, 180, 160, 140, 120, or 100 g/m ² . In various embodiments, the first nonwoven web can exhibit a solidity greater than about 8.0%, 9.0%, 10.0%, 11.0%, or 12.0% (measured according to the procedure outlined in US Pat. No. 8,162,153 to Fox). In various embodiments, the fibers of the first nonwoven web can exhibit a fiber diameter of at least about 10, 20, 30, or 40 microns. In various embodiments, the first nonwoven web can exhibit airflow resistance (ie, pressure drop) of less than about 1.0, 0.8, 0.6, or 0.4 mm water column (at a face velocity of 14 cm/sec), according to US Patent No. 8162153 of Fox. Program measurement as outlined in ).

In some embodiments, the first nonwoven web of the first reinforcement layer can be substantially free of charged fibers. In other words, in these embodiments, the first nonwoven web will not include any electrets. (It is known to the average person to be a quasi-permanent charge, and the presence of such quasi-permanent charges can be directly identified). In such cases, the first reinforcement layer may only be used primarily to reinforce the air filtration medium (ie, the first reinforcement layer may be used with little or no filtration of the fine particles, although the first reinforcement layer may of course block or capture, for example, some Very large dirt or debris particles). In other embodiments, the first nonwoven web of the first reinforcement layer can comprise fibers that are electrostatically charged. In such embodiments, the first reinforcement layer can be used to, for example, filter fines in addition to providing a reinforcing function. If the first nonwoven web of the first reinforcement layer is to be charged, the charging can be accomplished by any suitable method (e.g., by using water to impart a charge to the nonwoven web), such as in U.S. Patent No. 5,496,507 to Angadjivand. It is taught or taught in U.S. Patent Publication No. 2009/0293279 to Sebastian. The non-woven electret web can also be produced by charging a fiber by corona charging as described in U.S. Patent No. 4,588,537, to Klaase, or by a mechanical method as described in U.S. Patent No. 4,798,850, the entire disclosure of which is incorporated herein. Any combination of these methods can be used. The first reinforcement layer may be charged before being incorporated into the air filter medium 4; or after the air filter medium 4 is formed. (In any case, any such charging can be conveniently performed prior to pleating the air filter media 4.) In various embodiments, the first nonwoven web (eg, if charged) can exhibit less than about 50%, 40%, 30%, 20%, 10% or 5% penetration % (using dioctyl phthalate as a challenge material and tested using the method described in US Pat. No. 7,947,142 to Fox). In an alternative embodiment, the first nonwoven web (eg, if not energized) may exhibit a penetration % greater than about 80%, 90%, or 95%.

Second adsorbent layer

The second adsorbent layer 10 can comprise any suitable second nonwoven. In some embodiments, the second nonwoven web is substantially free of staple fibers; in other embodiments, the second nonwoven web is substantially free of spunbond fibers. In a particular embodiment, the second nonwoven web is a meltblown web.

By definition, the second nonwoven web comprises at least some of the fibers of the bonded fibers. This means a fiber that is bonded to the sorbent particles 14. In other words, at least some of the fibers of the second nonwoven web are selected to enable the fibers to be melt bonded to the adsorbent particles to form an inclusion A material that is at least partially trapped in the nonwoven web of adsorbent particles (discussed in detail below).

If the second nonwoven web is made by meltblowing, the adsorbent particles can be conveniently introduced into the positive flow of the initial fiber stream (the term initial fiber means that the fiber may have begun or may not have begun to solidify into fibers or complete the fiber). Solidified molten filament). A general method of performing such operations is disclosed in U.S. Patent Application Publication No. 20120272, the disclosure of which is incorporated herein by reference. Moreover, in some embodiments, the initial fibers that will form the second nonwoven web (along with the adsorbent particles incorporated into the initial fiber stream) can be conveniently deposited onto the first nonwoven web (which can, for example, be placed On the main surface of a surface such as a moving belt. The initial fibers can be deposited onto the first nonwoven web under conditions in which the initial fibers are at least slightly viscous (bondable). Such configurations may cause at least some of the fibers of the second nonwoven web to be bonded (e.g., melt bonded) to the fibers of the first nonwoven web (of the first reinforcement layer). In this manner, the second nonwoven web can be formed in a single operation and bonded (eg, melt bonded) to the first nonwoven web.

A variety of fiber-forming polymeric materials can be used to form the bonded fibers 12. Basically, any material that exhibits sufficient bonding (bonding) properties under the conditions used to prepare the second nonwoven web (e.g., meltblown conditions) can be used. Examples include thermoplastic materials such as polyurethane elastomeric materials (e.g., available under the trade designation IROGRAN Thermoplastic Polyurethane (from Huntsman International, LLC, The Woodlands, TX) and ESTANE Thermoplastic polyurethanes (from materials obtained from Lubrizol Corporation, Cleveland, OH.), polybutene elastomer materials (for example, under the trade name CRASTIN (from Wilmington, Delaware) Polycarbonate materials obtained by DuPont (EI DuPont de Nemours & Co., Wilmington, DE)), polyester elastomer materials (such as those available under the trade name HYTREL (from DuPont)), polyether blocks Copolyamide elastomeric materials (for example, under the trade name PEBAX (Arkema Inc., Philadelphia, PA) Philadelphia, PA)), polyolefin-based elastomeric materials (such as those available under the trade name VERSIFY (from Dow)), and elastomeric styrene block copolymerization (for example, the trade name KRATON (Kraton Polymers, Houston, TX) and SOLPRENE (Dynasol Elastomers, Houston, TX) Houston, TX)) obtained their materials). It is also possible to use multicomponent fibers (e.g., core-shell fibers, splittable membranes or side-by-side bicomponent fibers) and so-called "islands" in which at least one exposed surface of the fibers (e.g., the shell portion of the core-shell fibers) exhibits sufficient bonding properties. Type "fiber". Particularly suitable polymeric materials include polyolefin copolymers having a melting point of from about 122 °F to about 320 °F.

In some embodiments, the binder fibers 12 can be the only fibers present in the second adsorbent layer 10. In other embodiments, other fibers may be present (e.g., fibers that do not participate in any significant degree of binding of the adsorbent particles) as long as sufficient binder fibers 12 are present to achieve the effects disclosed herein. In various embodiments, the binder fibers 12 can comprise at least about 2%, at least about 4%, and at least about 6% by weight of the second adsorbent layer 10. In other embodiments, the binder fibers 12 can comprise no more than about 20% by weight, no more than about 17% by weight, and no more than about 15% by weight of the second adsorbent layer.

In at least some embodiments, the second sorbent layer is substantially free of any added binder of any kind. That is, in such cases, substantially all of the adhesion of the sorbent particles (so that the sorbent particles remain in the second sorbent layer) is carried out by the binder fibers 12. Such embodiments therefore do not include the presence of a binder in the form of particles or powders, liquids such as latexes, emulsions, suspensions or solutions.

Adsorbent particle

The sorbent particles 14 include at least some particles that can capture formaldehyde. In a particular embodiment, the sorbent particles comprise at least some activated carbon. In a particular embodiment, the adsorbent particles comprise at least some of the treated activated carbon, and the treated activated carbon is herein defined to mean Any activated carbon that has been treated to enhance its ability to capture formaldehyde. Suitable treatments may, for example, provide at least some amine functionality and/or at least some of the manganate functionality and/or at least some iodide functionality to the activated carbon. Specific examples of suitable treated activated carbons include those activated carbon which have been treated with, for example, potassium permanganate, urea, urea/phosphoric acid and/or potassium iodide. (Any desired combination of such treatments can be used.) Other adsorbent particles that may potentially be suitable, for example, for the removal of formaldehyde include, for example, treated zeolites and treated activated alumina. Such particles may be included, for example, along with the treated activated carbon, as desired.

The sorbent particles can be provided in any available form, including beads, flakes, granules or aggregates. In addition to activated carbon, other sorbent particles may be present for any desired purpose. Other such auxiliary adsorbents include, for example, alumina and other metal oxides; sodium bicarbonate; metal particle (eg, silver particles) catalysts such as hopcalite (which catalyzes the oxidation of carbon monoxide); nanoscale gold , which can catalyze the oxidation of carbon monoxide; clay and other minerals treated with an acidic solution such as acetic acid or an alkaline solution such as aqueous sodium hydroxide; ion exchange resins; molecular sieves and other zeolites; cerium oxide; biocides; Fungicides and viricides. However, in some embodiments, the sorbent particles consist essentially of activated carbon (eg, treated activated carbon).

The particle size of the adsorbent (e.g., activated carbon) can vary as desired. In various embodiments, the sorbent particles can have at least about 12 mesh (ie, nominally less than 1680 microns), at least about 16 mesh (<1190 microns), at least about 20 mesh (< 840 microns), at least A standard U.S. mesh size (grade) of about 40 mesh (<425 micron) or at least about 60 mesh (<250 micron). In further embodiments, the sorbent particles can have no more than about 140 mesh (ie, nominally greater than 105 microns), 100 mesh (>150 microns), 80 mesh (>180 microns), 60 mesh ( Standard US mesh size of >250 microns), 50 mesh (>300 microns), or 45 mesh (>355 microns).

One of ordinary skill will appreciate that such mesh sizes correspond to nominal levels rather than absolute standards; for example, if the material is described as a 12 mesh material, about 95% or more of the particles will pass through the 12 mesh screen. (and thus will have a nominal size of less than about 1680 microns). If The material is described as a 12 x 20 mesh, then 95% or more of the material will pass through a 12 mesh screen (ie, particles less than about 1680 microns will pass through the 12 mesh screen) and a 20 mesh screen Interception (i.e., particles larger than about 841 microns will not pass through the 20 mesh screen). Suitable sorbent particle size grades can include, for example, 12x20, 25x45, 30x60, and 50x100 mesh size granular activated carbon.

Mixtures of adsorbent particles having different size ranges (e.g., bimodal mixtures) can be used as desired. Suitable adsorbents (e.g., various treated activated carbons) can be, for example, from Calgon Corporation, Molecular Products, KOWA, Jacobi, Kuraray. ) and Oxbow Activated Carbon.

In various embodiments, the second adsorbent layer 10 can exhibit a basis weight of from about 100 g/m ² to about 625 g/m ² . In various embodiments, the second adsorbent layer 10 can exhibit a basis weight of adsorbent particles of at least about 100 g/m ² , at least about 150 g/m ² , at least about 200 g/m ^{2 ,} or at least about 300 g/m ² . In various embodiments, the sorbent particles can comprise at least about 80%, 85%, or 90% by weight of the total material of the second sorbent layer.

Third protective layer

The third layer 7 of the air filter medium 4 is a protective layer. This means that the third layer covers and protects the second adsorbent layer to ensure that the air filter media can be pleated. It has been found that if the major surface of the second nonwoven web (which provides the second adsorbent layer of the air filter medium) is exposed to the pleating process, then the adjacent surface of the second woven web is exposed on the exposed surface. Adhesive fibers can stick to each other (bonding). That is, the unique bondability of the fibers of the second nonwoven web to the adsorbent particles may unfortunately cause the exposed surfaces of the second nonwoven web to bond to each other during pleating of the filter media (sticky) even). Thus, in particular, if a relatively tight and/or deep pleated pattern is attempted on a filter medium having an exposed surface of the second sorbent layer, the pleated portion of the air filter media may be "accented" At least some stick together, rather than providing a high surface area pleated structure. Thus, the third nonwoven web provides a protective layer that prevents any exposed fibers of the second adsorbent layer from interfering with Pleating process.

The third non-woven fabric providing the third protective layer consists essentially of non-bonded fibers. By definition, non-bonded fibers are fibers that do not stick to each other when the air filter media is pleated. That is, non-bonded fibers exhibit little or no mutual adhesion under conditions used in conventional pleating processes, which often involve at least moderately high temperatures (eg, up to about 60 ° C or 85 ° C or slightly higher) and high pressures. tendency. One of ordinary skill will be able to readily identify such fibers. It will be apparent that all of the fibers previously described herein as bonded fibers (suitable for use in the second nonwoven) will not conform to the category of non-bonded fibers (suitable for use in the third nonwoven). In some embodiments, the non-bonded fibers can be polyolefin fibers, such as polypropylene homopolymers. The third non-bonded non-bonded fibers may or may not be electrostatically charged as needed.

The third non-woven fabric can be incorporated into the air filtration medium in any suitable manner to provide a third protective layer. It has been found that the fibers of the second non-woven fabric can be bonded (e.g., melt bonded) to the fibers of the third nonwoven web. Thus, in some embodiments, the third protective layer can be provided, for example, in the form of a prefabricated third nonwoven web that is in contact with the second nonwoven web. Application of, for example, an appropriate amount of heat and pressure may cause the fibers of the second non-woven fabric to be melt bonded to the fibers of the third non-woven fabric. (It should be noted that the above description of non-bonded fibers is such that they do not bond to one another under pleating conditions and do not preclude such fibers from being fused by the fibers of the second nonwoven web.) In other embodiments, the third may be used. The nonwoven web is deposited (collected) on top of the second adsorbent layer rather than in the form of a preformed web. If necessary, an auxiliary bonding measure (for example, point bonding by means of ultrasonic or adhesive means) may be used, for example, to strengthen the adhesion of the second adsorbent layer 10 to the first reinforcing layer 8 and/or to the third protective layer 7. .

Air filter media

As disclosed herein, an air filter medium 4 is provided that includes a second adsorbent layer 10 sandwiched between a first reinforcement layer 8 and a third protective layer 7. In various embodiments, the air filter media 4 can exhibit a basis weight of at least about 300 g/m ² , 400 g/m ^{2 ,} or 500 g/m ² . In further embodiments, the air filter media 4 can exhibit a basis weight of up to about 800 g/m ² , 700 g/m ^{2 ,} or 600 g/m ² . In at least some embodiments, the air filter media 4 can be relatively rigid (e.g., largely assisted by the rigidity of the first reinforcement layer), which can aid in pleating the media and maintaining the pleat spacing after pleating. ability. In various embodiments, the air filter media can exhibit a Gurley stiffness of at least about 800 mg, 1000 mg, 1200 mg, 1400 mg, or 1600 mg. In various embodiments, the air filter media 4 can exhibit a gas flow resistance (ie, a pressure drop) of less than about 8.0, 7.0, 6.0, 5.0, or 4.0 mm water column (at a face velocity of 14 cm/sec).

The air filter media 4 is pleated; a variety of known techniques can be used for pleat formation and pleat spacing, including those disclosed in U.S. Patent No. 4,798,575 to Siversson, U.S. Patent No. 4,976, 677 to Siversson, and U.S. Patent No. 5,389, 175 to Wenz. Their technology. A pleating procedure that may be useful is also described in, for example, U.S. Patent No. 7,235,115 to Duffy. (However, it will be appreciated that in at least some embodiments, the use of score pleating may be avoided, as the scoring process may be sufficient to comminute at least some of the sorbent particles.) It will be appreciated that, as mentioned earlier, pleating often involves High temperatures and high pressures are used, as described, for example, in U.S. Patent No. 7,510,518 to Heinen. The usefulness of the third protective layer will therefore be readily understood.

In various embodiments, the pleated air filter media 4 can include from about 0.5 to about 5 pleats per 2.5 centimeters. More specifically, the pleat spacing can be, for example, about 6 mm, 8 mm, 10 mm or 12 mm to about 50 mm, 40 mm, 30 mm, 20 mm, or 15 mm. In various embodiments, the pleat height can be, for example, about 15 mm, 20 mm, 25 mm, or 30 mm to about 100 mm, 80 mm, 60 mm, or 40 mm.

The air filter 2 includes a support frame 6. In the illustrated embodiment, the frame 6 is disposed around the peripheral edge region of the filter media 4. Suitable materials for the frame include particleboard or cardboard, synthetic plastic materials and metals. Suitable frame constructions may be selected from the "pinch" frame constructions illustrated in Figures 1 to 4 of U.S. Patent No. 6,126,707 to Pitzen; the "box" illustrated in Figures 5 and 6 of the '707 patent. Box structure; the hybrid frame construction illustrated in Figures 7 to 11 of the '707 patent; US Patent No. Sundet Any of the frame configurations disclosed in U.S. Patent No. 7,503,953; and any of the frame configurations disclosed in U.S. Patent No. 7,235,115 to Duffy. Often, a "slot" frame can be conveniently used, i.e. having a generally U-shaped cross section (wherein the bottom of the "U-shaped" provides a side wall 71 of the frame at least substantially upstream to downstream of the frame pleated filter Directional orientation, as shown in the illustrative embodiment of Figures 1 and 2. In some embodiments of the general type illustrated in Figures 1 and 2, the frame 6 can include a central generally planar grid-like portion 6a. During use, this central grid portion is typically positioned on the downstream side of the air filter. However, in other embodiments, there is no need to have this central mesh portion. Any such frame may be attached to the pleated air filter media 4 by any suitable means (e.g., hot melt bonding, room temperature glue, etc.).

In some embodiments, the frame pleated air filter 2 can include a sub-frame 200 as shown in FIG. (In Figure 1, only a portion of the sub-frame 200 is shown; however, in reality, the sub-frame 200 may conveniently extend along most or all of the length of all four edges of the pleated air filter media.) The sub-frame 200 may Any suitable material is included; for example, a non-woven material (which may be a relatively rigid material if desired). Sub-frame 200 can be obtained by obtaining a single length of material and cutting the material into a desired length corresponding to the total perimeter of the pleated media and a desired width corresponding to the total depth of the pleated filter media (in the direction of the airflow). . The sub-frame material can then be folded to match the perimeter of the pleated filter media and then wrapped around the perimeter of the media and attached to the edge of the media. Alternatively, the sub-frame material may be provided in four sections, each section being separately attached to the edge of the pleated filter media. Sub-frame 200 can be attached to the edge of the pleated filter media by any suitable method, such as a hot melt adhesive, a glue (e.g., applied at room temperature, etc.).

The frame 6 can then be attached to the periphery of the pleated filter media with the sub-frame 200 (where the inward surface of the side wall 71 of the frame 6 is attached to the outer surface of the sub-frame 200; and for the trough frame, the frame is upstream The flange and the downstream flange extend inwardly through the sub-frame 200, as shown in Figure 2). It has been found that providing sub-frame 200 in this manner can enhance frame 6 to pleated filtering The bonding of the media and/or can provide a better edge seal. In view of the possible presence of the sub-frame 200, the conditions for mounting the frame 6 to the periphery of the pleated filter media do not require the frame (in particular, the side walls 71 of the frame) to be in direct contact (or directly bonded) with the filter media.

In some embodiments, the frame pleated air filter 2 includes a plurality of unpleated strands 101, as shown in the exemplary embodiments of FIGS. 1, 2, and 4. These strands are bonded to the pleat tips of the major surfaces of the pleated air filter media 4, such as the first major surface 4a or the second major surface 4b. In some embodiments, such strands may be present on the two major surfaces of the pleated air filter media 4. After the air filter medium 4 has been pleated, the strands 101 are applied to the major surface of the air filter medium 4. The strands in Figure 4 are shown to be in discontinuous contact with the media, but the strands may also be provided in continuous contact with the media. However, by definition, the strands 101 are not pleated along with the pleated air filter media.

The strands 101 can help maintain the desired pleat spacing of the pleated air filter media 4. The strands 101 can be of any suitable type and configuration and can be made of any suitable material. The strands may be provided, for example, in the form of a grid, scrim or wire mesh or as a plurality of elongated strips or filaments of material. In some embodiments, the strands may be in the form of elongated strips of paper products (such as particleboard), polymeric materials, metals, glues, or combinations thereof. In some embodiments, the strands may be provided as pre-existing layers (eg, scrim, netting, grid, etc.). In other embodiments, the strands may, for example, be extruded or coated (in a flowable form) onto the major surface of the pleated filter media and then solidified.

Regardless of the particular configuration and configuration, the strand 101 as defined herein must extend between at least two of the pleat tips of the major surface of the pleated filter media 4 and be bonded to the at least two pleat tips; or, the strand must Bonding to other strands and/or entanglement with other strands such that the strands collectively bridge the distance between at least two pleat tips (where at least some of the strand portions in contact with the pleat tips are bonded to such Pleated tip). That is, in some exemplary embodiments, the strands may take the form of generally linear members, such as filaments, which extend, for example, directly between the pleat tips, as in the strand of Figure 1. In an exemplary configuration of 101. In other exemplary embodiments, the strands may be collectively provided by fibers such as non-woven mesh (scrim), although the fibers are individually too short and/or oriented such that the fibers are not between the pleat tips Extending, but the fibers are bonded to other fibers and/or entangled with other fibers to collectively bridge the distance between adjacent pleat tips. In other exemplary embodiments, the strands may be collectively derived from, for example, an expanded metal (e.g., a product available from Wallner Tooling/Expac, Rancho Cucamonga, Calif.). The strands are provided, although a single segment of the metal filament (between the junctions with the other individual segments) may (or may not be) long enough to extend between the two pleat tips. However, in at least some embodiments, the strands 101 will comprise an average length of at least 100%, 200%, 400%, or 800% of the spacing between consecutive pleat tips of the major faces of the pleated air filter media, and/ Or it will be configured such that at least some of the individual strands extend between the at least two pleat tips of the major surface of the pleated filter media and are bonded to the at least two pleat tips.

In the absence of pleats, the strands 101 can often comprise a generally planar configuration (as shown in the illustrative embodiment of Figure 2). However, in some embodiments, at least some of the strands may follow the contour of the pleats partially or even continuously, as illustrated by strand 101 of FIG. Such strands and methods of applying such strands to a pleated air filter media are described in detail in U.S. Patent No. 7,235,115 to Duffy. (It is emphasized that at least some of the strands are at least partially conformable along the contour of the pleated air filter media as long as the strands are not actually pleated along with the air filter media.)

In some embodiments, at least some of the strands 101 can be oriented at least substantially perpendicular to the pleat direction of the pleated filter media 4 (eg, within 90 degrees +/- about 5 degrees) (where the pleat direction is meant to be with the pleat tips Parallel direction). (See strand 101 of Figure 1 is substantially strictly perpendicular to the direction of the pleats.) In such cases, the strands may extend between, for example, three, four, eight or more pleat tips and bond to These pleated tips. In some embodiments, at least some of the strands may be continuous, meaning that the strands extend along the entire length of the pleated filter media. In some embodiments, the strands 101 are at least substantially straight; and at least some of the strands can be at least substantially parallel to each other. However, it will be appreciated that many configurations are possible. In some embodiments, at least some of the strands can be attached to the perimeter frame 6. In other embodiments, no strands are attached to the perimeter frame 6.

As noted above, the strands 101 are not pleated together with the pleated filter media 4. In fact, the stiffness imparted by the first reinforcement layer (and the help of the strand 101 (if present)) may allow the pleated configuration to be maintained once the pleated configuration is formed. Thus, it may not be necessary to provide any support structure that is bonded to the primary surface of the pleated filter media and that is pleated along with the air filter media. Thus, in some embodiments, there will be no support structure that is bonded to the major surface of the pleated filter media and pleated along with the filter media. However, in other embodiments, there may be such a pleated support structure (eg, a screen that is adhesively bonded to the air filter media and pleated therewith).

The frame pleated air filter 2 can be used in any situation where it is desirable to remove formaldehyde from the air (and optionally, remove fines). The frame pleated air filter 2 can therefore be used in any type of forced air system, such as an HVAC system. In a particular embodiment, the frame pleated air filter 2 can be used in an air purifier such as an indoor or domestic air purifier. In order to more fully understand the present work described herein, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and should not be construed as limiting the present invention in any way.

Working example testing method

The pleat spacing, percent penetration, and flow resistance (pressure drop) are determined using the general method outlined in U.S. Patent Application Publication No. 20120272829 to Fox. Airflow resistance (pressure drop) was measured on a flat medium at a face velocity of 14 cm/sec and reported in millimeters of water. Gurley stiffness is measured in the general manner described in U.S. Patent No. 7,947,142 to Fox; in this example, the sample has a length of about 1.5 inches and a width of 2.0 inches. Geli Rigid values are reported in milligrams as is well known to those of ordinary skill.

Formaldehyde is produced by heating the paraformaldehyde solution in a 50% humidity air stream having a flow rate of 0.5 m/s filter surface speed. The photoacoustic detector from California Analytical Instruments was used to measure the formaldehyde concentration. The filter formaldehyde efficiency is calculated by the following formula: efficiency % = 100 × (1-C _downstream (in the filter used) / C _downstream (unused filter)), where C is the formaldehyde in the flowing air stream concentration. The filter formaldehyde removal capacity was determined by integrating the area under the efficiency curve from the start of the test in Figure 5 until the filter sample passed the 5% efficiency and multiplying the area by the mass flow rate of formaldehyde. The final measurement to 5% efficiency is shown in dashed lines in Figure 5 and the results are extrapolated using a linear best fit equation. These results are presented in Table 1 below as "Adsorbent Capacity". One of ordinary skill will appreciate that a variety of suitable analytical techniques can be used to measure formaldehyde in this concentration range.

Working example 1

A three-layer air filter media is formed using a procedure substantially similar to that described in Example 1 of U.S. Patent Application Publication No. 2012272829, the entire disclosure of which is incorporated herein. Briefly, the first nonwoven web (a spunbonded polyester web obtained from Johns Mannsville under the trade designation 568/90, having a basis weight of 92 g/m ² and a gas flow resistance of 0.45 mm water column) ) placed on the surface of the moving collector (belt). The collector surface having the first nonwoven web at the top is passed under the meltblowing device such that a mixed stream of (initial) fibers and activated carbon particles is deposited on top of the first nonwoven web. The fibers are made from a melt extrudate comprising a thermoplastic elastomer obtained from the Dow Chemical Company under the trade name Versify 4301; the activated carbon is a 32 x 60 mesh treated activated carbon. The composition of the combined adsorbent and fibers is about 9.9% by weight of fibers and about 90.1% by weight of activated carbon. The meltblown fibers form a second meltblown web. The meltblown fibers are sufficiently bonded to the activated carbon (and bonded to each other) to form a second adsorbent layer (the layer is bonded to the first reinforcement layer provided by the first nonwoven fabric).

The third non-woven fabric (the general type of spunbonded polypropylene web described in PCT Patent Application No. US2014/053640, having a basis weight of 39 g/m ² and a gas flow resistance of 0.27 mm water column) and a second The exposed surface of the sorbent layer is in contact. Under these conditions, the third non-woven fabric is lightly bonded to the second adsorbent layer to provide a third protective layer of the three layers of air filtration media.

The resulting three-layer air filter medium had a basis weight of 574 g/m ² , a gas flow resistance of 1.23 mm water column, and a total adsorbent content (basis weight) of 398 g/m ² . The web was pleated using a folding knife pleating machine with a pleat height of 25 mm and a pleat spacing of 12.5 mm. The pleating device is maintained at about 80 °C. Under these conditions, the media does not require any support material to be laminated to the media (before pleating) to pleat with it to successfully form and maintain a pleated shape. After the pleating process, the strip of cardboard is adhesively attached to the pleat tips of one major surface of the pleated media to maintain a consistent pleat spacing.

To evaluate the ability to remove formaldehyde, the pleated air filter media was not bonded to the frame, and the pleated air filter media was bonded to a test fixture that prevented air from leaking around the edges of the pleated air filter media. The ability of the pleated air filter media to remove formaldehyde from the flowing air stream was tested. As a comparative example, a commercially available 30 mm thick honeycomb air filter (a type supplied by an indoor air purifier of the KJEA-400 model available from 3M Company), containing treated activated carbon and untreated A 50:50 blend of activated carbon with a total adsorbent basis weight of about 3600 g/m ² was tested. The working example pleated air filter and comparative examples were each exposed to a challenge air stream containing 8.7 ppm formaldehyde; the air stream was maintained at a relative humidity of about 50% and flowed at a face velocity of 0.5 m/s. As illustrated in Figure 5, the working example 1 pleated air filter exhibited much higher initial formaldehyde removal efficiency and was maintained with higher efficiency over the entire test duration.

The adsorbent capacities obtained as described above by Working Example 1 compared to the comparative examples are presented in Table 1. The sorbent capacity is obtained by calculating the ratio of the mass of the captured formaldehyde (filter medium per unit area) to the mass of the adsorbent being captured (again, the filter medium per unit area). The adsorbent capacity was calculated according to the above procedure.

It will be apparent that while the working example pleated filter media contains less than half the amount by weight of the comparative example (by weight), the working example pleated filter media is capable of removing much higher amounts of formaldehyde. That is, the working example pleated filter media exhibits a much higher sorbent capacity. One of ordinary skill will appreciate that high initial formaldehyde removal efficiency and combination of formaldehyde removal efficiency and high adsorbent capacity over the life of the filter will result in advantageously high CADR (Clean Air Output Rate).

The pleated filter was also formed into a frame filter having a size of 370 x 400 mm. A cardboard perimeter frame was used in which the frame overlaps the filter face by about 20 mm on the downstream side of the filter. The same strip of cardboard is attached to the pleat tips of one major surface of the pleated media in a bonded manner to maintain a consistent pleat spacing. According to the ASHRAE 52.2 test method, the working example 1 filter and the comparatively sized (cellular) filter were subjected to pressure drop and efficiency tests at a surface speed of 0.5 m/s. Working Example 1 exhibited initial airflow resistance of 16 Pa and initial E1 efficiency of 6% (average efficiency of 0.3 to 1.0 μm), initial E2 efficiency of 18% (average efficiency of 1.0 to 3.0 μm), and initial E3 efficiency of 58% (3 to 10 micron average efficiency); the comparative (cellular) filter has an initial resistance of 32 Pa, 1% E1 and 7% E2 and 23% E3.

Working example 2

Another three layer air filter media was formed using the general procedure outlined above. In this case, the first non-woven fabric is a static-type spunbond web of the general type described in U.S. Patent No. 7,947,142. The first non-woven fabric had a basis weight of 102 g/m ² , a solidity of 11%, and a percent penetration (DOP) of 16%.

The meltblown fiber (of the second adsorbent layer) is made of a melt extrudate, the melt extrudate Contains thermoplastic elastomers available from ExxonMobil under the trade name VISTAMAXX 2125. The weight ratio was 8.7% by weight of the fiber and 91.3% by weight of the same activated carbon as the activated carbon in Working Example 1.

The third non-woven fabric (spun polypropylene web similar to the spunbonded polypropylene web of Working Example 1, but the spunbonded polypropylene web having a basis weight of 41 g/m ² and a gas flow resistance of 0.30 mm water column) and the second The exposed surface of the sorbent layer is in contact while the second sorbent layer (and the first reinforcement layer) is still on the collector. Under these conditions, the third non-woven fabric was more strongly bonded to the second adsorbent layer than in Working Example 1 to provide a third protective layer of the three-layer air filter medium.

The resulting three-layer air filter medium had a basis weight of 567 g/m ² , a gas flow resistance of 4.41 mm water column, and a total adsorbent content (basis weight) of 388 g/m ² . The web was pleated using a folding knife pleating machine with a pleat height of 25 mm and a pleat spacing of 12.5 mm. The pleating device is maintained at about 80 °C. Similar to Working Example 1, the media does not require any support material to be laminated to the media (before pleating) to pleat with it to successfully form and maintain a pleated shape. The web of cardboard is adhesively attached to the pleat tips of one major surface of the pleated media to maintain a consistent pleat spacing.

The pleated filter was also formed into a frame filter having a size of 370 x 400 mm. A cardboard perimeter frame was used in which the frame overlaps the filter face by about 20 mm on the downstream side of the filter. The same strip of cardboard is attached to the pleat tips of one major surface of the pleated media in a bonded manner to maintain a consistent pleat spacing. According to the ASHRAE 52.2 test method, the pressure drop and efficiency test of the working example 2 filter having a charged layer upstream was performed at a surface speed of 0.5 m/s. Working Example 2 exhibited an initial airflow resistance of 62 Pa, an initial E1 of 93%, an initial E2 of 98%, and an initial E3 of 99.9%.

The above examples are provided for clarity of understanding only, and it should be understood that such examples do not constitute an unnecessary limitation. The tests and test results described in the examples are intended to be illustrative and not predictive, and variations in the test procedures are expected to produce different results. In view of the procedures used The commonly known tolerances referred to in the examples, all values in the examples should be understood as approximations.

It will be apparent to those skilled in the art that the specific illustrative elements, structures, features, details, configurations, etc. disclosed herein may be modified and/or combined in many embodiments. All such variations and combinations are considered by the creator to be within the scope of the inventive concept, and are not merely selected as representative designs. Therefore, the scope of the present invention should not be limited to the specific illustrative structures described herein, but should be extended to at least the structures described in the language of the claims and equivalents. Any element that is affirmatively described in this specification as an alternative may be explicitly included in the scope of the patent application or excluded from the scope of the patent application in any combination. Any element or combination of elements recited in the open language (eg, including its derivatives) is considered to be additionally in a closed language (eg, composed of and its derivatives) and a partially closed language (eg, Basically composed of ... and its derivatives) narrative. To the extent that there is any inconsistency or discrepancy between the present disclosure and the disclosure in any of the documents incorporated herein by reference, the present specification is incorporated by reference.

2‧‧‧Frame pleated air filter

4‧‧‧Pleated air filter media

4a‧‧‧ first major surface

4b‧‧‧ second major surface

4c‧‧‧ peripheral edge area

6‧‧‧Support frame

6a‧‧‧Grid-like part

71‧‧‧ side wall

101‧‧‧ unpleated strands

200‧‧‧Subframe

Claims (22)

A frame-type pleated air filter, the air filter comprising: a pleated air filter medium comprising a first major surface and a second major surface comprising a plurality of oppositely facing pleats, and comprising a peripheral edge region; and a support frame mounted to the peripheral edge region of the pleated air filter medium; wherein the air filter medium comprises a first reinforcement layer, the first reinforcement layer being a first nonwoven web And a second adsorbent layer, the second adsorbent layer being a second nonwoven web comprising one of the adsorbent particles; and wherein the frame type air filter medium is characterized by a third protective layer, the third protective layer a third nonwoven web and on a side opposite to the first reinforcement layer of the second adsorbent layer, wherein the first nonwoven web of the first reinforcement layer is selected from a spunbond web and A group of short fiber webs. The frame pleated air filter of claim 1, wherein the second nonwoven web of the second adsorbent layer is a meltblown web. The frame pleated air filter of claim 1, wherein the first nonwoven web of the first reinforcement layer exhibits a Gurley rigidity of at least about 100 mg. The frame pleated air filter of claim 1, wherein the adsorbent particles are activated carbon particles. The frame pleated air filter of claim 1, wherein the adsorbent particles are treated activated carbon particles. The frame pleated air filter of claim 1 wherein the adsorbent particles are treated activated carbon particles having a standard mesh size of from about 20 mesh to about 100 mesh. child. A frame pleated air filter of claim 1 wherein the second nonwoven web of the second sorbent layer comprises at least some of the binder fibers bonded to at least some of the sorbent particles. The frame pleated air filter of claim 7, wherein the fibrous material of the second nonwoven web consists essentially of the bonded fibers and is substantially free of any non-bonded fibers. The frame pleated air filter of claim 1, wherein the third nonwoven web of the third protective layer consists essentially of non-bonded fibers and is substantially free of any adhesive fibers. The frame pleated air filter of claim 1, wherein there is no intervening layer between the second adsorbent layer and the first reinforcing layer, and wherein the second adsorbent layer of the second non-woven web At least some of the fibers are bonded to at least some of the fibers of the first spunbond web of the first reinforcement layer. The frame pleated air filter of claim 1, wherein there is no intervening layer between the second adsorbent layer and the third protective layer, and wherein the second adsorbent layer of the second non-woven web At least some of the fibers are bonded to at least some of the fibers of the third nonwoven web of the third protective layer. The frame pleated air filter of claim 1 , wherein the pleated air filter does not include the first major surface attached to the pleated air filter media or attached to the pleated air filter media The second major surface is any support structure that is pleated along with the pleated air filter media. The frame pleated air filter of claim 1, the air filter further comprising a plurality of unpleated strands bonded to the pleat tips of one of the major surfaces of the pleated air filter media. The frame-type pleated air filter of claim 1 is characterized in that the second adsorbent layer The second nonwoven web does not include any staple fibers. The frame pleated air filter of claim 1, wherein the second nonwoven web of the second sorbent layer does not include any added binder. The frame pleated air filter of claim 1, wherein the first nonwoven web of the first reinforcement layer comprises fibers with static electricity. The frame pleated air filter of claim 16, wherein the air filter media exhibits a particle filtration quality factor of at least about 0.3. The frame pleated air filter of claim 1, wherein the first nonwoven web of the first reinforcement layer is substantially free of static-charged fibers. The frame pleated air filter of claim 18, wherein the air filter media exhibits a particle filtration quality factor of less than about 0.1. The frame pleated air filter of claim 1 is characterized in that the layer of the pleated air filter media does not include any electret fibers. A frame pleated air filter according to claim 1, wherein the support frame has a trough frame of a U-shaped cross section. The frame pleated air filter of claim 1, the air filter further comprising a sub-frame constructed of a nonwoven material and attached to the peripheral edge of the pleated air filter medium, and wherein the support The frame is attached to at least one of the outer surfaces of the sub-frame.