KR20100059839A - Liquid filtration systems - Google Patents

Abstract

Provided are filter elements and methods of making and using the same where the filter elements are suitable for liquid filtration and contain a particle-loaded meltblown fiber web. A filter element comprises: a porous article comprising a web of self-supporting nonwoven polymeric fibers and a plurality of sorbent particles enmeshed in the web, the article comprising a first surface and a second surface; a liquid-impermeable housing surrounding the porous article; an inlet in fluid communication with the first surface; and an outlet in fluid communication with the second surface. A plurality of layers of the web of self-supporting nonwoven polymeric fibers may be used to the porous article. Spiral-wound webs, web-covered blocks, and stacked disks of webs are also provided.

Description

LIQUID FILTRATION SYSTEMS

The present invention relates to filter media and liquid filtration systems comprising, for example, polymeric fibrous webs containing sorbent components.

Many types of fluid filtration systems are commercially available, such as for household water filtration. Traditionally, coarse layers of carbon particles have been used to remove metals and / or organics from water. Composite blocks can be made from a combination of sorbent materials such as adsorbent activated carbon and polymer binders such as polyethylene that are sintered together under conditions of heat and pressure and are useful in water filter technology. Carbon block technology, for example, provides a function equivalent to coarse carbon particle layers without particle shedding or taking up too much space. With carbon block technology, the pressure drop across the block can be increased as a result of increasing the amount of sorbent material such as activated carbon. In addition, exposure of the carbon block to heat and pressure may limit the type of material available for the block. For example, carbon block technology generally excludes the use of materials that are sensitive to thermal degradation, such as ion exchange resins.

There is a continuing need to provide compact water filtration systems for home use. There is also a need to provide a system with a high loading of active material without increasing the pressure drop across the system. It would also be desirable to minimize degradation of the filter media during processing. Moreover, there is a continuing need to provide a system with an improved service life.

Filter elements suitable for liquid filtration and containing particle-loaded meltblown fibrous webs and methods of making and using the same are provided.

In one aspect, a porous article comprising a web of self-supporting nonwoven polymeric fibers and a plurality of sorbent particles enmeshed within the web and comprising a first surface and a second surface; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A filter element is provided that includes an outlet in fluid communication with the second surface.

Another aspect includes a porous article comprising a fluid source and a filter element, the filter element comprising a web of self-supporting nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web and comprising a first surface and a second surface; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; And a fluid filtration system comprising an outlet in fluid communication with the second surface.

In another aspect, a block composite comprising an active medium in an amount ranging from 10 to 90% by weight of the block and a binder in an amount ranging from 10 to 90% by weight; A web is provided that includes a web surrounding the carbon block composite, the web comprising a self-supporting nonwoven polypropylene fiber and a plurality of sorbent particles trapped within the web in an amount in the range of 50 to 97% by weight of the web.

In another aspect, a filter element is provided that includes a plurality of disks attached to each other comprising self-supporting nonwoven polypropylene fibers and a plurality of sorbent particles trapped within the fibers.

Another aspect includes a fluid filtration method. The method includes a web of self-supporting nonwoven polymeric fibers and a porous article comprising a first sorbent particle and a plurality of sorbent particles trapped within the web; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; Contacting the fluid with a filter element comprising an outlet in fluid communication with the second surface.

In a further aspect, flowing the molten polymer through a plurality of orifices to form a filament; Thinning the filaments into fibers; Directing a stream of sorbent particles between the filaments or fibers; Collecting the fibers and sorbent particles as a nonwoven web to form a porous article; A method of forming a filter element is provided that includes positioning a porous article in a liquid impermeable housing.

Also provided are methods for making and using directly-formed filtration articles using particle loaded meltblown fiber web structures and for fluid purification.

In one aspect, a plurality of porous layers comprising a web of self-supporting nonwoven polymer fibers and a plurality of sorbent particles captured within the web to form a porous article; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A filter element is provided that includes an outlet in fluid communication with the second surface.

Another aspect includes a first plurality of porous layers wound to form a porous article and comprising a first web of self-supporting nonwoven polypropylene fibers and a plurality of carbon particles trapped within the first web; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A filter element is provided that includes an outlet in fluid communication with the second surface.

Further aspects include a plurality of porous layers wound to form a porous article and comprising a web of freestanding nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A method of fluid filtration comprising contacting a fluid with a filter element comprising an outlet in fluid communication with a second surface.

In another aspect, flowing the molten polymer through a plurality of orifices to form a filament; Thinning the filaments into fibers; Directing a stream of sorbent particles between the filaments or fibers; Collecting the fibers and sorbent particles on the spindle as a nonwoven web to form a porous article; There is a method of forming a filter element comprising positioning a porous article in a liquid impermeable housing.

<Figure 1>
1 is a schematic cross-sectional view of a porous article.
<FIG. 2>
2 is a cross-sectional view of a porous article positioned within a housing.
3,
3 is a schematic view of the housing;
<Figure 4>
4 is a cross sectional view of a spiral wound porous article positioned within a housing;
<Figure 5>
5 is a cross-sectional view of the stacked disk filter located in the housing.
6,
6 is a schematic of an exemplary component for making a directly-formed particle loaded porous article.
<Figure 7>
7 is a schematic representation of a porous article.
<Figure 8>
8 is a cross-sectional view of a porous article.
<Figure 9>
9 is a cross-sectional view of the porous article.
Before describing some exemplary embodiments of the invention, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced or carried out in various ways.

A filtration article for liquid clarification is provided that uses a meltblown (or blown microfiber-BMF) web loaded with particles to form a liquid processing unit. These particle loaded BMF webs are provided by adding a sorbent material in the form of particles, particulates and / or agglomerates or blends thereof to an airstream that thins the polymer meltblown fibers and delivers them to the collector. Is formed. The particles are trapped in the meltblown fibrous matrix as the fibers are collected to contact the particles in the mixed airflow to form a web. Large amounts of loading (eg up to about 97% by weight) of particles are possible. The sorbent material includes, but is not limited to, various types of materials that change the physical or chemical properties of the fluid, such as absorbent and adsorbent materials and materials with surface activity. Examples of sorbents include granular and powdered activated carbon; Ion exchange resins; Metal ion exchange zeolite sorbents such as ATS from Engelhard; Activated alumina, such as Alusil from Selecto Scientific; Antimicrobial compounds such as silver, zinc and halogen based materials; Acid gas adsorbents; Arsenic reduction material; Iodide resins; And diatomaceous earth, but are not limited thereto.

Filtration media according to embodiments of the present invention include particle loaded webs (not calendared) and compacted / densified loaded webs (calendered). These media exhibit low resistance to fluid flow and have significant improvements over commercially available products, for example in liquid filtration applications of gravity flow. Further advantages are found in applications requiring high flow rates. The open porosity properties of these loaded webs do not significantly add resistance to flow through the filter and the housing. This low pressure drop across the media enables use in high flow applications such as whole household filtration and also for applications that require gravity flow filtration. Activated carbon loadings in excess of 90% by weight have been described. Loading amounts of at least 40, 50, 60, 70, or even 80% are also possible. Loaded webs have additional advantages over block technology when using thermosensitive particulates such as some ion exchange resins. The particles are not exposed to elevated temperatures experienced during the block molding or extrusion process. This reduces the concern about thermal lability associated with particulate (ion exchange resin) degradation. Coarse porous structures are also advantageous in high precipitation situations. Highly coarse structures maintain many possible pathways for fluid to come into contact with the particles. In whole household filtration, one wants to allow large precipitated particles to be trapped in the medium and smaller precipitated particles to pass through the medium. This contributes to a longer service life before the media is blocked and the pressure drop is excessive.

In one aspect, a porous article comprising a web of freestanding nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web and comprising a first surface and a second surface; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A filter element is provided that includes an outlet in fluid communication with the second surface.

In a specific embodiment, the sorbent particles comprise activated carbon, diatomaceous earth, ion exchange resins, metal ion exchange sorbents, activated alumina, antimicrobial compounds, acid gas adsorbents, arsenic reducing materials, iodide resins, or combinations thereof.

In another embodiment, the web has a Gurley time of 2 (or in other embodiments 1 or even 0.5) seconds or less. Another embodiment provides that the filter has a pressure drop of less than 150 (or 75 or even 30) mm water at a uniform face velocity of 5.3 cm per second under ambient conditions. In certain embodiments, the particles have an average particle size of 250 (or 200, 150, 100, or even 60) μm or less. Detailed embodiments provide that the filter has an average fill rate of less than 38 Lpm (10 minutes per gallon).

In one embodiment, the web is wound to form an article. In another embodiment, the article is formed of a plurality of webs adjacent to each other. Detailed embodiments provide that the first web contains the first sorbent and the second web contains the second sorbent. Another embodiment provides that the first web comprises particles of a first average size and the second web comprises particles of a second average size.

In another embodiment, the web substantially surrounds the core. The core may comprise a carbon block. Other embodiments include webs having a base web weight in the range of 10 to 1000 (or 20 to 300 or even 25 to 100) grams per square meter. In another embodiment, the web has a sorbent particle density in the range of 0.20 to 0.5 g / cc.

In one or more embodiments, the polymeric fiber comprises polypropylene. In some embodiments, the polymer fibers comprise metallocene-catalyzed polyolefins. In detailed embodiments, the polypropylene has a polymer melt flow index in the range of 30 to 1500 (or 75 to 750, or even 200 to 500).

Further embodiments provide that the web is compressed by calendering, heating, or applying pressure. Another embodiment includes a filter element having a sorbent density gradient.

Another aspect includes a porous article comprising a fluid source and a filter element, the filter element comprising a web of self-supporting nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web and comprising a first surface and a second surface; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; And a fluid filtration system comprising an outlet in fluid communication with the second surface.

In one embodiment, the web is wound to form a porous article. In another embodiment, the porous article is formed of a plurality of webs adjacent to each other. In another embodiment, the web substantially surrounds the carbon block.

In another aspect, a block composite comprising an active medium in an amount ranging from 10 to 90% by weight of the block and a binder in an amount ranging from 10 to 90% by weight; A web is provided that includes a web surrounding the carbon block composite, the web comprising a self-supporting nonwoven polypropylene fiber and a plurality of sorbent particles trapped within the web in an amount in the range of 50 to 97% by weight of the web.

In another aspect, a filter element is provided that includes a plurality of disks attached to each other comprising self-supporting nonwoven polypropylene fibers and a plurality of sorbent particles trapped within the fibers. Detailed embodiments provide that the first plurality of disks include first sorbent particles of activated carbon and the second plurality of disks include second sorbent particles of ion exchange resin.

Another aspect includes a fluid filtration method. The method includes a web of self-supporting nonwoven polymeric fibers and a porous article comprising a first sorbent particle and a plurality of sorbent particles trapped within the web; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; Contacting the fluid with a filter element comprising an outlet in fluid communication with the second surface.

In a further aspect, flowing the molten polymer through a plurality of orifices to form a filament; Thinning the filaments into fibers; Directing a stream of sorbent particles between the filaments or fibers; Collecting the fibers and sorbent particles as a nonwoven web to form a porous article; A method of forming a filter element is provided that includes positioning a porous article in a liquid impermeable housing. In one embodiment, the method further includes compressing the nonwoven web by calendering, heating, or applying pressure to form a compressed web having a Gurley time of 2 seconds or less. In another aspect, the method further includes attaching a plurality of nonwoven webs adjacent to each other to form a porous article. Another embodiment provides that the method further includes winding the nonwoven web before placing the nonwoven web in a housing. Another embodiment includes controlling the rheology of the fibers.

Also provided is a filtration article for liquid clarification formed by directly collecting a meltblown or blown microfiber (BMF) filament containing particles, particulates or aggregates of a sorbent directly onto a rotating mandrel collector. These particles are loaded into the stream as the BMF filament stream is transported out of the die and into a rotating mandrel collector. The addition of sorbent material may remove additional unwanted chemicals and contaminants from the source water or liquid to be purified. Such treatment forms a filter diameter in the layer as the filter element is formed. In some embodiments, the filter elements traverse laterally.

Certain BMF filament fibers without any sorbent material were designed to remove particulates and precipitates from the water source. Representative examples of such processes are described in US Patent Application Publication Nos. 2004/0245171 and 2007/0175819 (Schimmel), the disclosures of which are incorporated herein by reference.

When the BMF web is formed by adding the sorbent material in the form of particles, particulates and / or aggregates or blends thereof, to the airflow that thins the polymer meltblown fibers and transports them to the collector, the particles are mixed with the fibers. It is trapped in the meltblown fibrous matrix as it is collected in contact with the particles in the air stream to form a web. Large amounts of loading (eg up to about 97% by weight) of particles are possible. Sorbent materials include, but are not limited to, various types of materials that change the physical or chemical properties of the fluid, such as absorbent and adsorbent materials. Examples of adsorbents include granular and powdered activated carbon; Ion exchange resins; Metal ion exchange zeolite sorbents such as Engelhart's ATS; Activated alumina, such as aluminus of selector scientific; Antimicrobial compounds such as silver, zinc and halogen based materials; Acid gas adsorbents; Arsenic reducing materials; And iodide resins, but are not limited thereto.

The directly-formed filter element may comprise a density gradient achieved by the control of meltblown filaments, loaded particulates or both. In one or more embodiments, the meltblown filament air stream is modified to produce various effects. Filament size distributions of different blends can be formed by mixing fiber airflows generated from two or more separate dies operating at different target effective fiber diameters (EFDs). Similar effects can be obtained by the use of mixed blown or alternating fiber die tips as disclosed in US patent application Ser. No. 11 / 461,136, the disclosure of which is incorporated herein by reference. The mixed blown approach can also be used to create zones across die faces with different sized fibers or gradients of fiber sizes. By doing so, the structure of the filter layer can be tailored to be used, for example, in a depth filter. Into one or more of these filament streams, particles, particulates, aggregates, other regular, irregular or hollow shapes or mixtures thereof can be added and collected on a rotating mandrel or an advancing collecting mandrel to form a filter element.

Another aspect is to have two or more dies operating in separate layers instead of having a mixed filament air stream. The die may also be operated side-by-side to create a pronounced stacking effect as the elements traverse on the rotating mandrel. Further variations in performance may be possible by using different polymers or multicomponent fibers in one or more of the dies.

Inclined or flat stacked filter elements can be formed using an advancing collector mandrel by allowing the particle loader to add particulates only to the targeted area of the web. This can be accomplished by using a narrow particle loader with a wider die, or by using a patterned feed roll in the particle loader. The feed roll uses a machined cavity to control the volumetric feed rate as the roll pivots against the doctor blade. By varying the volume of the cavity across (or around) the face of the feed roller, the local-feed of the microparticles and thus the local-addition weight of the microparticles in the resulting web can be controlled.

Another approach is to use segmented hoppers in the particle loader. Particulates are only added to the segmented areas where feeding is desired to occur. This approach would also allow the use of different particle sizes in the segmented area, or would have controlled the addition of treated sorbents or sorbents with special performance. Multiple particle loaders can be used to vary the amount or type of particles loaded into the targeted area.

By using these approaches, direct-formed filter elements can be formed that are tailored to a particular application. For example, the inner layer of fine polypropylene fibers can be formed directly adjacent to the mandrel core that will help reduce sloughing and dropout. Following the inner layer, an intermediate layer of particle loaded web for primary separation can be provided. Moreover, on the intermediate layer, an outer layer of desired function can be formed, for example the outer layer can have a larger pore size and / or additionally to remove larger contaminants before reaching the primary separation layer. It can have fibers of larger diameter to act as a pretreatment-filter layer of. Many other possible configurations may also be devised by those skilled in the art and are considered to be within the scope of the present invention.

In one aspect, a plurality of porous layers comprising a web of self-supporting nonwoven polymer fibers and a plurality of sorbent particles captured within the web to form a porous article; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A filter element is provided that includes an outlet in fluid communication with the second surface. In one embodiment, the plurality of porous layers are fused together. In another embodiment, the plurality of porous layers is a separate composite layer. In a specific embodiment, the sorbent particles comprise activated carbon, diatomaceous earth, ion exchange resins, metal ion exchange sorbents, activated alumina, antimicrobial compounds, acid gas adsorbents, arsenic reducing materials, iodide resins, or combinations thereof.

In some embodiments, the filter element further comprises a core surrounded by the web. Another embodiment provides that the web has a sorbent particle density in the range of 0.20 to 0.5 g / cc.

In one or more embodiments, the polymeric fiber comprises polypropylene. Some embodiments provide that the polymer fiber comprises a metallocene-catalyzed polyolefin. In one embodiment, the metallocene-catalyzed polyolefin comprises polypropylene. In another embodiment, the polypropylene has a polymer melt flow index in the range of 30-1500.

In one embodiment, the first plurality of layers comprises polymer fibers having a first effective fiber diameter and the second plurality of layers comprises polymer fibers having a second effective fiber diameter. In another embodiment, the polymeric fiber comprises a mixture of effective fiber diameters.

In yet another embodiment, the sorbent particles are present at a first density in the first plurality of layers and at a second density in the second plurality of layers. Another embodiment includes the first plurality of layers comprising a first sorbent and the second plurality of layers comprising a second sorbent. In another embodiment, the first plurality of layers comprises particles having a first average size and the second plurality of layers comprises particles having a second average size.

Detailed embodiments provide that the filter element has a sorbent density gradient in the axial configuration. Another detailed embodiment provides that the filter element has a sorbent density gradient in the radial configuration.

In one embodiment, the filter element further comprises a plurality of layers of a second web of freestanding nonwoven polymeric fibers that are substantially free of sorbent particles.

Another aspect includes a first plurality of porous layers wound to form a porous article and comprising a first web of self-supporting nonwoven polypropylene fibers and a plurality of carbon particles trapped within the first web; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A filter element is provided that includes an outlet in fluid communication with the second surface. In one embodiment, the porous article further comprises a second plurality of porous layers, the porous layer comprising a second web of self-supporting nonwoven polypropylene fibers and an ion exchange resin trapped within the second web.

Further aspects include a plurality of porous layers wound to form a porous article and comprising a web of freestanding nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; A method of fluid filtration comprising contacting a fluid with a filter element comprising an outlet in fluid communication with a second surface.

In another aspect, flowing molten polymer through a plurality of orifices to form a filament; Thinning the filaments into fibers; Directing a stream of sorbent particles between the filaments or fibers; Collecting the fibers and sorbent particles on the spindle as a nonwoven web to form a porous article; A method of forming a filter element is provided that includes positioning a porous article in a liquid impermeable housing.

In one embodiment, the method further comprises forming a first plurality of layers comprising polymer fibers having a first effective fiber diameter and a second plurality of layers comprising polymer fibers having a second effective fiber diameter. It includes. Another embodiment provides that the method further comprises providing the sorbent particles at a first density in the first plurality of layers and at a second density in the second plurality of layers. In another embodiment, the method further comprises providing a first plurality of layers with a first sorbent and a second plurality of layers with a second sorbent. In another embodiment, the method further includes controlling the rheology of the fibers.

Reference to “particle loaded meltblown media” or “web” includes filtration media of fibers (containing particles trapped between fibers), for example, a coarse-structured coarse mass of microfibers. And particles are sorbents for reducing or removing substances such as chemical contaminants, chlorine and precipitates from water.

Reference to "captured" means that the particles are dispersed and physically retained in the fibers of the web. In general, there are point and line contacts along the fiber and the particles such that the nearly entire surface area of the particles can be useful for interaction with the fluid.

Reference to “sorbent density gradient” suggests that the amount of sorbent material per square area need not be uniform throughout the filter and may vary to provide more material in some areas of the filter and less material in other areas. It means to be. For example, the sorbent density gradient in the axial configuration is from the central portion, although the amount of sorbent per square area at one end of the filter, when along the central portion of the filter, is different from the amount at the other end and between the two ends. It means that it does not change in the radial direction away. On the other hand, the sorbent density gradient in the radial configuration means that the core region has a different amount of sorbent relative to the outer surface of the filter as it moves away from the central portion of the filter. The change in density need not be linear and can vary as needed. For example, the density may vary with a single step change, multiple step changes, a sinusoidal change, and the like.

Reference to "fluid processing unit" or "fluid filtration system" includes systems and methods including filtration media that separate raw fluid, such as untreated water, from the treated fluid. This typically includes a filter housing for the filter element and an outlet for directing the treated fluid away from the filter housing in a suitable manner.

The terms particles and particulates are used interchangeably with each other. Generally, the particles are small pieces or individual parts. Particulates belong to or form particles. The particles used in embodiments of the present invention can be kept separate or can be aggregated, physically interlocked, electrostatically associated, or otherwise associated to form particulates. In certain cases, aggregates such as those described in US Pat. No. 5,332,426 (Tang et al.) May be intentionally formed.

Reference to “calendering” includes the process of passing a product, such as a polymer absorbent loaded web, through a roller to obtain a compacted material. The roller may optionally be heated.

The term "galling time" refers to the time it takes for 50 cc of air to pass through a sample of a web having a circular cross-sectional area of approximately 645 mm 2 (1 square inch) at a pressure of 1.2 kPa (4.88 inch) H ₂ O). Say Temperatures of approximately 23-24 ° C. (74-76 ° F.) and 50% relative humidity are maintained for consistent measurements. "Gary" time is W. in Troy, NY, USA. And L. this. Calibrated with Gurley-Teledyne sensitivity meter (catalog number 4134/4135) of the type sold under the trade name "Model 4110" densometer by W. & LE Gurley. And an actuated densimeter. Gurley time is inversely related to the void volume of the particle loaded web. Gurley time is also inversely related to the average pore size of the particle loaded web.

The terms "melt flow index" or "MFI", which are also variously referred to as MFR or Melt Flow Rate, are defined by test method ASTM 1238. Polypropylene polymers were measured using the "Method B" variant of the ASTM 1238 test method.

The term “meltblown process” refers to the production of fine fibers by extruding a thermoplastic polymer through a die consisting of one or more holes. As the fiber emerges from the die, the fiber is tapered by a stream of air running generally parallel or tangential to the emerging fiber.

The term "pore volume" refers to a percentage calculated by measuring the weight and volume of a filter and then comparing the filter weight with the theoretical weight of a solid mass of the same constituent material of that same volume.

The term "thermal deterioration" refers to the effect of heat applied to a material. For example, some sorbent particles formed from composite blocks or loaded webs can be physically unstable during processing such as sintering or calendering. For polymers such as polypropylene, treating the polymer with heat alone or with mechanical action can result in cleavage, cross-linking, and / or chemical change of the polymer chain.

The term "controlled degradation" refers to agents which are consumed in the degradation reaction by controllable means, for example by specific heat and / or shear input rate, or by breaking the polymer chain and in proportion to the amount of polymer Reduction of molecular weight and narrowing of the molecular weight distribution of a polymer by introduction of is included.

The term "porosity" is a measure of the void space in a material. The size, frequency, number and / or interconnectivity of the pores and pores contribute to the porosity of the material.

The term “controlled rheology” can be defined as the use of radiation, peroxides or other free radical agents to control the rheological properties (such as viscosity and molecular weight distribution) of a given polyolefin, such as polypropylene, by deterioration.

The term “densification” allows fibers deposited directly or indirectly on a filter winding axis or mandrel to be pressed before or after its deposition, and as an artifact of some process by design or forming or handling the formed filter. , A process that is made to form a region of smaller porosity as a whole or locally. Densification also includes the process of calendering the web.

Particle loading process

The particle loading process is an additional treatment step to the standard meltblown fiber forming process, as disclosed, for example, in US Patent Publication No. 2006/0096911, incorporated herein by reference and commonly assigned. Blown microfibers (BMF) are produced by molten polymer that enters and flows through a die, where flow is distributed to the die cavity across the width of the die and the polymer is filament from the die through a series of orifices. Come out. In one embodiment, heated airflow passes through an air manifold and an air knife assembly adjacent to a series of polymer orifices forming a die outlet (tip). This heated air stream can be controlled both in temperature and speed to taper (stretch) the polymer filament to the desired fiber diameter. In this turbulent air flow the BMF fibers are carried towards the rotating surface where they are collected to form a web.

Desired particles, such as adsorbent particles, for example activated carbon particles or ion exchange resin beads, are loaded into a particle hopper that gravitationally fills the concaved cavity in the feed roll. Rigid or semi-rigid doctor blades with segmented control zones form a controlled gap for the feed roll to limit flow out of the hopper. The doctor blade is usually adjusted to contact the surface of the feed roll to limit the particulate flow to the volume present in the recess of the feed roll. The feed rate can then be controlled by adjusting the speed at which the feed roll rotates. The brush roll operates behind the feed roll to remove any residual particulates from the recessed cavity. Particulates are dropped into another source of pressurized gas or into a chamber that can be pressurized with compressed air. Such chambers are designed to create an airflow that will transport particles and allow the particles to mix with the meltblown fibers carried thinned by the airflow exiting the meltblown die.

By adjusting the pressure of the pressurized air particulate stream, the velocity distribution of the particles is changed. When very slow particle speeds are used, the particles may be diverted by the die airflow and not mixed with the fibers. At slow particle speeds, particles can only be captured on the upper surface of the web. As the particle velocity increases, the particles may begin to more fully mix with the fibers in the meltblown air stream to form a uniform distribution in the collected web. As the particle velocity continues to increase, the particles are partially captured through the meltblown air stream and trapped in the lower portion of the captured web. At even higher particle velocities, the particles can pass completely through the meltblown airflow without being trapped in the captured web.

In another embodiment, the particles are sandwiched between two filament airflows using two generally vertically sloped-dies that inject generally opposed filament streams toward the collector. On the other hand, the sorbent particles pass through the hopper and enter the first chute. The particles are gravity fed into the filament stream. The mixture of particles and fibers is opposed to the collector and forms a freestanding nonwoven particle loaded nonwoven web.

In other embodiments, the particles are provided using vibration feeders, eductors, or other techniques known to those skilled in the art.

In many applications, a substantially uniform distribution of particles throughout the web is required. In some cases, a non-uniform distribution may be advantageous. Gradients through the depth of the web can produce changes in the pore size distribution that can be used for deep filtration. A web with surface loading of particles may be formed into a filter if the fluid is exposed to the particles early in the flow path and the balance of the web provides a means to prevent the particles from falling off the support structure. The flow path may also be reversed so that the meltblown web can act as a pre-filter to remove some contaminants before the fluid reaches the active surface of the particles.

In a further embodiment, the collector is placed on a winding mandrel, or on a rotating cantilever shaft with a sort of filter cartridge extraction device designed to substantially pull / push the forming filter cartridge out of the rotating shaft. And a cartridge winding mechanism operable to form.

Polymer Rheology Control

The controlled rheology of the polymers used in the meltblown fibers can be tailored such that the web has the desired properties. This is discussed by US Patent Application Publication Nos. 2004/0245171 and 2007/0175819 (Summel), which are hereby incorporated by reference in their entirety and jointly assigned. For example, adjusting the viscosity of polypropylene, for example, can increase the strength of the web. High fiber to fiber bonding is desirable so that the filter can be machined into useful shapes such as grooved cylinders while maintaining good flow properties and large void volume.

For polypropylene, controlled degradation of the polypropylene starting material characterized by low MFI (large molecular weight) results in modified polypropylene having desirable properties for use in making particle loaded meltblown webs.

In one embodiment, the web is made of polypropylene polymer using controlled degradation to provide a material that exhibits a melt flow index of about 30 to about 1500 (or in other embodiments 75 to 750, or even 200 to 500). do.

In another exemplary embodiment of the invention, controlled degradation is thermally performed by radiation, with or without oxygen, to produce a polypropylene polymer having a melt flow index of about 35 to about 350, or Or by the action of free radicals produced by one or more of various reactants such as peroxides upon heating. Thus, advantageous modifications of the rheology and physical properties of polypropylene are realized by controlled degradation of the polymer.

Referring to FIG. 1, the porous article 10 is schematically shown in cross section. The article 10 has a thickness T and has a length and width of any desired dimension. The article 10 is a nonwoven web that includes intertwined polymeric fibers 12 and sorbent particles 14 trapped within the web. Small connected pores in the article 10 (not shown in FIG. 1) allow water or other fluid to pass (eg, flow) across the thickness dimension of the article 10. Particles 14 modify the fluid passing through, for example, to absorb, adsorb, or otherwise modify contaminants and particulates present in such fluids.

2 is a cross-sectional view of a housing 20 including a filter element comprising a porous web-shaped article 24 disposed on a porous core 22. End cap 26 is attached to web 24, for example with an adhesive (not shown). The inlet 28 into the housing 20 directs a fluid, such as water, to the web 24, where the fluid contacts the sorbent particles trapped in the web and is processed. The treated fluid enters into the channel 27 formed by the core 22. The treated fluid then exits the housing through the outlet 29.

3 shows a schematic view of a housing 30 with an inlet 38 and an outlet 39. Such a housing is suitable for the filter element implemented by the present invention.

4 shows a cross-sectional view of a housing 40 having a wall 41 with a filter element comprising a spiral wound porous web-shaped article 44 with a channel 47. End cap 46 is attached to web 44, for example with an adhesive (not shown). Fluid such as water enters the web 44 and is processed in contact with the sorbent particles trapped in the web. The treated fluid enters the channel 47 formed by the core 22.

5 shows a cross-sectional view of a stacked disk 54 of web-like material located in a housing 50 with an inlet 58 into the disk. The fluid contacts the stacked disk 54 and the reservoir 59 collects the treated fluid.

With reference to FIG. 6, a schematic of exemplary components of a system for making a directly-formed particle loaded porous article is provided. A collector assembly 114 is shown that includes a rotating mandrel 122 having an inner end 124 rotatably mounted on a support (not shown) through a bearing. Mandrel 122 also has an open distal end 116, an inner surface 120, and an outer circumferential surface 126. Meltblown die 112 feeds non-woven particle loaded fibers 110, 110a, 110b, 110c, 110d, 110e toward collector assembly 114 to form a directly-formed web structure.

7 and 8, a schematic and cross-sectional view of a porous article 130 formed from a layer 138 of a nonwoven web 132 containing particles 134 is shown, respectively. Fluid to be treated enters layer 138 and the treated fluid flows through channel 136. In this embodiment, the density of the particles is substantially uniform throughout the article. In FIG. 9, another cross-sectional view of a porous article is provided, in which a particle density gradient is illustrated. In section 142, there are more particles per unit area than in area 144, which in turn has more particles per unit area than in section 146.

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, etc., used in this specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters recited in the following specification and the appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and without attempting to limit the application of the theory equivalent to the scope of the claims, each parameter value should at least be interpreted in terms of the number of significant digits recorded and by ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. However, all numerical values inherently contain certain errors that inevitably arise from the standard deviation found in each experimental measurement.

EXAMPLE

A series of screening experiments was performed to characterize the performance of particle loaded meltblown webs for water purification applications. 350 MFI polypropylene sold under two types of base resin, trade name type 3960 (available from Total Petrochemicals), and trade name Vistamaxx 2125 (available from ExxonMobil). 80 MFI metallocene-catalyzed polypropylene sold as Several particle size grades of coconut shell activated carbon sold under the trade name NC506 (available from PICA) were evaluated. Titanium sold under the name Nuchar Aquaguard (available from Mad Westvaco) and wood-based carbon under the trade name ATC N60260 (available from Calgon). Coconut shell carbon with silicate coating, coconut shell carbon sold under the name YPC 100MD (available from Kuraray), and under the trade name Dowex HCR-S (available from Dow Chemical) Additional examples of webs using cation exchange resins sold were included for specific tests.

Short yard length rolls of the loaded web approximately 25.4 cm (10 inches) wide were collected under the following conditions. The polymer was 25.4 cm (3.6 kg / hr (8 lb / hr) for polypropylene-based webs and 3.0 kg / hr (6.5 lb / hr) for metallocene-catalyzed-polypropylene-based webs). Extruded through an inch wide width perforated orifice die (DOD). The distance between the die-collectors was 31.0 cm (12 inches). Samples of the base web (no loaded particulates) were collected at a targeted basis weight and subjected to the method described in Davies, CN, "The Separation of Airborne Dust and Particles," Institution of Mechanical Engineers, London Proceedings 1B, 1952. The effective fiber diameter (EFD) was evaluated accordingly. Air temperature and speed were adjusted to achieve the targeted effective fiber diameter. Melt temperatures were recorded for various samples.

After adjusting the base web conditions to reach the targeted basis weight and effective fiber diameter, the particulates were added to the particle loader hopper and the feed roll speed was adjusted to deliver the desired loading of adsorbent (carbon or ion exchange resin). The air pressure in the particle loader chamber was set at 0.5 to 2 psig (3.4-13.8 kPa). The setting was adjusted with the aim of a uniform distribution of particles throughout the web. Basis weight was reported in grams per square meter (gsm). Base webs are expressed in weight per square meter of (unloaded) meltblown fiber webs. The loaded web is expressed as weight per square meter of meltblown fiber web loaded with media particles.

TABLE 1

Certain webs were selected from Example 1 to evaluate the impact of calendaring on performance. A calendar with an adjustable gap between smooth chrome plated steel rolls was used. The calendar pressure for the sample was 414 kPa (60 psi) and the roll speed was 1.5 meters / minute (5 feet per minute). The roll was 25.4 cm (10 inches) in diameter and had a roll face of 56 cm (22 inches) wide. Each roll weighed about 272 kg (600 pounds) when filled with the oil used to control the temperature by the Sterlco system. A cylinder with a 13 inch (5 inch) ID was used to apply the nip pressure.

The air pressure drop across the particle loaded web was measured for the calendered web and the corresponding input web sample. The air pressure drop was measured at room temperature (approximately 22 ° C.) at an ambient pressure of 1 atmosphere (101 kPa) at a uniform plane velocity of 5.3 cm / sec relative to the air flow.

TABLE 2

The web did not adhere to the calender rolls under the conditions evaluated. The web has increased overall width and possibly length, especially at higher temperatures. Web density was improved over uncalendered webs. The basis weight of the web is included to account for the change in dimensions after calendaring.

Some samples of Example 1 and Example 2 were assembled into filters as follows. For each sample, the length of the web needed to obtain a filter containing approximately 100 grams of media was calculated from the resulting weight of one section of a web of approximately size 20 cm (8 inches) W x 30.5 cm (12 inches). It was. Cores of rigid tubes of approximate dimensions of 3.7 cm (1.45 inch) OD and 35.3 cm (13.9 inch) length were obtained. The tube included an approximately 0.38 cm (0.15 inch) square opening throughout the tube. Calculated length webs for delivering 100 grams of media were cut from the full width—typically 10 inch sample rolls. Webs of approximately 91 cm to 122 cm (3 to 4 feet) long (depending on the amount of loading) generally resulted in approximately 100 gram loading when cut to 20 cm (8 inches) long. The web was adhered to the OD of the tube. The web was wound around the tube to the appropriate length. The outer edge of the web is bonded to the inner layer of the web. One end of the tube was cut at a point where good loading was seen. The other end was cut to produce a filter approximately 8 inches (20.3 cm) in length. The ends of the filter were placed in the end cap.

The filter averaged 2.7 cm (OD). The OD ranged from 6.1 cm to 7.3 cm (2.41 inches to 2.88 inches). This OD resulted in an average media load of 106 grams ranging from 99 to 114 grams. Web-based filters using uncalendered webs had an average density of 0.20 g / cc of active medium.

Calendering of the carbon loaded web formed a more dense filter structure. As a result, the use of calendered webs reduced the volume of material required for the filter, allowing the use of small filter dimensions. The density of the filter using the calendered web ranged from 0.37 g / cc to 0.50 g / cc. The highest density of the calendered web (Sample 4) was 0.45 g / cc of active medium.

exam

Several filters formed in accordance with Example 3 were subjected to various performance tests including initial flush turbidity, clean pressure drop, chlorine reduction, particulate reduction, gram life test, and Gurley values. Evaluated according to.

For initial flush turbidity, a filter was connected to the tap water supply and the first water collected through the filter. The method is based on a comparison of the intensity of light scattered by a standard reference under the same conditions as the intensity of light scattered by the sample under defined conditions. Higher amounts of scattered light indicate higher levels of haze in water. Data was recorded in Nephelometric Turbidity Unit or NTU. Levels below 0.5 NTU meet the NSF / ANSI drinking water standard. The first liter was collected from the effluent stream. Turbidity was measured and recorded. The sample was then allowed to flow at 2.8 L / min (0.75 gpm) and additional samples were collected at 3.8 liters (1 gallon), 19 liters (5 gallons), and 38 liters (10 gallons), each sample point. Turbidity was measured at. Data for Comparative Example 1, a composite carbon block having a formulation of 55% activated carbon medium and 45% polymeric binder, and Comparative Example 2, a carbon filter formed from granular activated carbon (GAC), are included.

[Table 3]

In connection with Table 3, the loaded web dropped off the carbon microparticles during the initial 0-19 L (0-5 gallon) of flow. Web capture was better for larger carbon particles than for smaller particles. The microparticles were found to decrease between 3.8 and 19 L (1 to 5 gallons). The dropout amount was below the standard GAC axial flow filter, even for particles of 80 × 325 mesh size (except sample 15 and sample 16).

Calendering did not increase the initial flush turbidity. Calendering also appears to have reduced initial turbidity, especially in the case of 80 × 325 carbon.

For pure pressure drop, the filter was connected to the tap water supply with the calibrated pressure gauge positioned immediately before the system. The filter was opened to the atmosphere at the outlet of the system. A tachometer capable of measuring the flow rate at the desired rate corresponding to 0.9, 1.9, 2.8, 3.8, 7.6, 11.4 and 15.1 L / min (0.25, 0.50, 0.75, 1.0, 2.0, 3.0 and 4.0 gallons per minute), respectively through a rotometer. The pressure drop of the medium with and without medium was evaluated at various flow rates. A system without media is identified as Comparative Example 3.

[Table 4]

In relation to Table 4, in all cases, the observed pressure drop for the system and loaded web filter was within 41.4 psi (6 psi) of the system pressure drop for the sump with and without filters. There was no appreciable contribution to the total pressure drop from the web filter. No evidence of filter damage was observed during this test.

Uncalendered sample 17 web media was removed from the retained filter from the pressure drop test. Scanning electron microscopy was used to measure the size of retained particles after the high pressure test. These filters showed retention of particles having a size of 60 to 65 micrometers or more. Calendaring webs, the use of finer diameter fibers, or other techniques to reduce the intersticial space between particles and fibers or to form bonds or bonds therebetween, maintain even finer particle sizes. Should be increased.

For the NSF / ANSI 42 chlorine abatement test, with an influent challenge concentration of 2.0 mg / L free available chlorine (FAC) with water having a specified pH, turbidity, total organic carbon and water hardness The filter was challenged at a flow rate of 3.024 L / min (0.8 gallon / min). To meet chlorine abatement requirements, the filter must meet a minimum 50% reduction in effluent or a maximum of 1.0 mg / L free residual chlorine. The comparison block, referred to as “Comparative Example 4”, had dimensions of 16.2 cm (6.395 inches) long, 3.8 cm (1.5 inches) OD, 0.95 cm (0.375 inches) ID, and US Pat. No. 7,112,272 (Hughes et al. ) Was a carbon block containing 60% by weight 80 × 325 PICA NC506 carbon and 40% polyethylene binder. The end cap was adhesively bonded directly to the open end of the carbon block. Percent reductions are reported in Table 5.

TABLE 5

Regarding Table 5, because filter samples were made with a defined mass of medium, similar results were obtained between the calendared and uncalendered samples in the chlorine abatement test.

For the NSF / ANSI 42 particulate abatement test, the filter was challenged at an initial flow rate of 9.5 L / min (about 2.5 gallons / minute) with an inlet particle counter of about 1,000,000 particles for a Class III test. According to the NSF / ANSI 42 standard, the system must reduce the number of particles in the test particle size range by at least 85% when tested according to the standard to accommodate specific class grades. The rating of the system should be consistent with the minimum particle size that is effectively removed as measured by the test. The demand for larger percentile reductions should be specified by test if possible. Comparative Example 4 was also tested.

TABLE 6

With respect to Table 6, calendared Sample 39 and Sample 40 show improved particulate removal compared to comparative carbon blocks.

For the gram life test, the filter was exposed to an aqueous solution of AC Coarse Test Dust at a defined concentration of 1 gram of test dust per gallon. The end point was measured by a 20 psi change in pressure drop across the medium. The quantity of liters (gallons) through the filter to the designated end point was recorded. Larger gram life when measured using these test dusts indicates longer service life. Comparative Example 4 was also tested.

TABLE 7

In connection with Table 7, uncalendered samples 20 and 24 showed peak gram lifetimes greater than 2.5 to 40 times greater than the comparison block.

For Gurley value testing, as described in US Pat. No. 5,328,758 (Markell), 50 cc of air at 124 mm water pressure resulted in an area of approximately 645 square mm (1 square inch) at room temperature (approximately 23 ° C.). A Gurley model 4110 densimeter was used to measure the time it takes to pass a sample of the having web. The samples presented in Table 4 represent the range of pressure drops shown in Table 2.

[Table 8]

Regarding Table 8, Gurley values were less than 1 second for various filters using both calendared and uncalendered webs.

The webs according to sample 20 (coconut-based carbon loaded web) and sample 26 (cationic exchange loaded web) of Example 1 were assembled into filters as follows. These test samples were prepared by adhesively bonding 100 mm diameter disks of loaded web media along the inner edge of a 100 mm OD plastic ring with a 94 mm ID opening. Fine beads of hot melt adhesive were added around the circumference of the 100 mm diameter disk of the loaded web medium. Another 100 mm disk was stacked (as adhesive) directly on top of the previous layer. This stacking was repeated for seven layers of carbon loaded webs, followed by the targeted layers of ion exchange loaded webs, followed by three additional layers of carbon loaded webs. Another plastic ring was adhesively bonded to the top of the media stack. Stacked filters using the loaded web were assembled according to Table 9.

TABLE 9

exam

The filter of Example 5 was evaluated for TTHM reduction and gravity flow through rate.

For the NSF / ANSI 53 TTHM Reduction Test, first filter the filter by pouring 18.9 liters (5 gallons) of appropriate NSF / ANSI universal test water through the filter to condition the filter's total trihalomethane or TTHM reduction. Evaluated. The filter was tested using chloroform challenge influent with 450 +/- 90 ppb under gravity flow conditions. The data recorded below were collected using pour through device conditions (gravity flow) as described in the ANSI 53 standard.

TABLE 10

In connection with Table 10, Sample 46 and Sample 47 met the NSF 53 TTHM criteria for 227 liters (60 gallons) and 265 liters (70 gallons), respectively, based on the maximum effluent concentration of 80 ppb chloroform allowed. These results for TTHM removal show an improvement in gravity filtration based on grams of gallons / carbon treated. The comparative Brita OB01 / OB03 Classic style pitcher requires approximately 150 grams of active medium to meet at least 303 liters (80 gallons) during the test. This is compared with Sample 46 and Sample 47 containing 68-77 grams of active medium. Moreover, the flow rate was approximately four times faster than the Brita product for Sample 46 and Sample 47.

For gravity flow rate, the incremental time for each liter (gallon) of solution to pass through the filter of Example 5 was measured.

TABLE 11

For comparison, the Brita OB01 / OB03 Classic is reported to typically require 15 minutes to pass 1.9 liters (0.5 gallons). PUR Ultimate feature filters have been reported to take about 15 minutes to filter enough water to fill a 1.9-2.3 L (8-10 cup) glass bottle.

Some samples of Example 1 and Example 2 were assembled into filters as follows. Carbon blocks having dimensions of 20.3 cm by 2.9 cm (8 "L by 1.125") OD by 1.8 cm (0.7 ") ID were prepared using the process described in US Pat. No. 7,112,272 (Hugh et al.). Was 20% Aquagard 80 × 325 activated carbon and 80% polyethylene binder.The particle loaded web material was wound around a carbon block until the resulting structure was approximately 7.6 cm (3 inches) OD 20 cm (8 inches). Sections were cut for testing to a final length of 5 inches (13 cm) End caps were adhesively bonded to both ends of the composite structure.

A comparative product called "Comparative Example 5" comprises 70% active medium and 30% polymer binder. The end caps were adhesively bonded directly to both ends of the carbon block.

exam

Filters formed according to Example 7 were evaluated for chloramine reduction according to the NSF / ANSI 42 chloramine reduction test. The maximum effluent concentration according to this standard is 0.5 ppm. Comparative Example 5 was also tested.

TABLE 12

Regarding Table 12, the calendered samples 42 and 43 were kept at less than 0.5 ppm chloramine while the amount of test liquid through the filter was greater than twice as compared to Comparative Example 5.

The directly formed cylindrical filter was formed into a meltblown web. Metallocene-catalyzed polypropylene sold under the Vistamax 2125 (available from ExxonMobil) was extruded through a 2.5 inch (10 inch) wide punched orifice die at 2.9 kg / hr (6.5 lb / hr). . The melting temperature was about 265 ° C. for all samples. The distance between the die-collectors was 30.5 cm (12 inches). Base web samples (no loaded particulates) were collected and characterized for condition recording. The base web had a basis weight of 53 gsm. The thickness was 0.355 mm (0.014 inches). The pressure drop of 5.4 kPa (0.55 mm H ₂ O) at 1 atmosphere pressure and room temperature (approximately 22 ° C.) was measured at a uniform face velocity of 5.3 cm / sec relative to air flow. These conditions correspond to an effective fiber diameter (EFD) of 19 micrometers according to the method described in Davis, CN, "The Separation of Airborne Dust and Particles," Institution of Mechanical Engineers, London Proceedings 1B, 1952.

After reaching the targeted effective fiber diameter, the fines were added to the particle loader hopper and the feed roll speed was adjusted to deliver approximately 90% by weight of 60 × 140 of coconut-based activated carbon sold under the trade name Pica NC506. The air pressure in the particle loader hopper was set at about 2.5 psig to provide a uniform distribution of particles throughout the web.

After confirmation of the conditions, the particle loaded meltblown or blown microfiber (BMF) filaments were collected on a rigid tube with approximate dimensions of 3.7 cm (1.45 inch) OD and 35.2 cm (13.9 inch) length. The tube included an approximately 0.38 cm (0.15 inch) square opening throughout the tube. This tube was mounted on the shaft and held in place by two rubber stoppers sliding along the shaft. This shaft was mounted in the chuck of a variable speed hammer drill operating at a maximum setting of 850 rpm. The paired spacers were extended 10 cm (4 inches) from the collector surface to provide a reproducible distance from the die to the mandrel. As the sample was collected, the mandrel shaft could be held lightly against these spacers (on each end of the tube). The tube and shaft were allowed to reach a maximum rotational speed and then introduced into the particle loaded meltblown or blown microfiber (BMF) filament air stream. The collection time was varied to control the weight of the particle loaded filaments collected on the tube. The core weighed 37 g in the full length sample. The weight of each core was measured before and after collection to reveal the variation related to the contact of the particle loaded filament air stream with the mandrel.

TABLE 13

exam

Several filters formed in accordance with Example 9 were evaluated according to several performance tests including initial water turbidity, pressure drop and chlorine reduction.

For initial flush turbidity, the test was performed as described in Example 4.

[Table 14]

The initial water turbidity of Sample 49, Sample 51, Sample 52, and Sample 54 was greater than Comparative Example 1 shown in Table 3, but smaller than Comparative Example 2 in Table 3. As the cylinder's OD increased, the initial water turbidity improved. In all cases, turbidity was reduced to levels below 0.5 NTU.

For pure pressure drop, the test was performed as described in Example 4. A cylinder without loading is "Comparative Example 6".

TABLE 15

The net pressure drop of these filters was small and such filters would be advantageous for whole household filtration applications.

For the NSF / ANSI 42 chlorine reduction test, the test was performed as described in Example 4.

TABLE 16

In relation to Table 16, all samples removed acceptable levels of chlorine for at least 8.7 kL (2300 gallons) during the test based on the 50% minimum reduction required by the standard. Liters (gallons) of treated water were directly related to the mass of the amount of active medium. Sample 57 performed best and was still decreasing beyond 90% of the influent challenge after 30.2 kL (8000 gallons). This is surprising due to the particle size of the carbon used and the small pressure drop of the structure.

Reference throughout this specification to “one embodiment”, “predetermined embodiment”, “one or more embodiments” or “an embodiment” refers to a particular feature, structure, material, or aspect described in connection with the embodiment. It means that the characteristic is included in at least one embodiment of the present invention. Thus, expressions of phrases such as "in one or more embodiments", "in certain embodiments", "in one embodiment" or "in one embodiment" in various places throughout this specification are not necessarily set forth in the present invention. The same embodiments are not mentioned. In addition, certain features, structures, materials, or properties may be combined in any suitable manner in one or more embodiments.

Although the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments merely illustrate the principles and applications of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the methods and apparatus of the present invention without departing from the spirit and scope of the invention. Accordingly, the invention is intended to embrace modifications and variations that fall within the scope of the appended claims and their equivalents.

Claims (58)

A porous article comprising a web of self-supporting nonwoven polymeric fibers and a plurality of sorbent particles enmeshed within the web and comprising a first surface and a second surface;
A liquid impermeable housing surrounding the porous article;
An inlet in fluid communication with the first surface;
A filter element comprising an outlet in fluid communication with the second surface. The filter element of claim 1, wherein the sorbent particles comprise activated carbon, diatomaceous earth, ion exchange resins, metal ion exchange sorbents, activated alumina, antimicrobial compounds, acid gas adsorbents, arsenic reducing materials, iodide resins, or combinations thereof. . The filter element of claim 1, wherein the web has a Gurley time of 2 seconds or less. The filter element of claim 1 having a pressure drop of no more than 150 mm water at a uniform face velocity of air of 5.3 cm per second under ambient conditions. The filter element of claim 1, wherein the particles have an average particle size of 250 μm or less. The filter element of claim 1 having an average fill rate of less than 38 minutes per liter (10 minutes per gallon). The filter element of claim 1, wherein the web is wound to form an article. The filter element of claim 1, wherein the article is formed from a plurality of webs adjacent to each other. The filter element of claim 8, wherein the first web comprises a first sorbent and the second web comprises a second sorbent. The filter element of claim 8, wherein the first web comprises particles of a first average size and the second web comprises particles of a second average size. The filter element of claim 1, wherein the web substantially surrounds the core. The filter element of claim 11, wherein the core comprises a carbon block. The filter element of claim 1, wherein the base web weight is in the range of 10 to 1000 grams per square meter. The filter element of claim 1, wherein the web has a sorbent particle density in the range of 0.20 to 0.5 g / cc. The filter element of claim 1, wherein the polymer fiber comprises polypropylene. The filter element of claim 1, wherein the polymer fiber comprises a metallocene-catalyzed polyolefin. The filter element of claim 13, wherein the polypropylene has a polymer melt flow index in the range of 30 to 1500. The filter element of claim 1, wherein the web is compressed by calendering, heating, or applying pressure. The filter element of claim 1 having a sorbent particle density gradient. A fluid source and a filter element,
The filter element is
A porous article comprising a web of freestanding nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web and comprising a first surface and a second surface;
A liquid impermeable housing surrounding the porous article;
An inlet in fluid communication with the first surface;
And an outlet in fluid communication with the second surface. The filter element of claim 20, wherein the web is wound to form a porous article. The filter element of claim 20, wherein the porous article is formed of a plurality of webs adjacent to each other. The filter element of claim 20, wherein the web substantially surrounds the carbon block. A block composite comprising an active medium in an amount ranging from 10 to 90% by weight of the block and a binder in an amount ranging from 10 to 90% by weight;
A web surrounding the carbon block composite,
The web includes a self-supporting nonwoven polypropylene fiber and a plurality of sorbent particles trapped within the web in an amount in the range of 50 to 97% by weight of the web. A filter element comprising a plurality of disks attached to each other comprising self-supporting nonwoven polypropylene fibers and a plurality of sorbent particles trapped within the fibers. 27. The filter element of claim 25 wherein the first plurality of disks comprise first sorbent particles of activated carbon and the second plurality of disks comprise second sorbent particles of ion exchange resin. A porous article comprising a web of freestanding nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web and comprising a first surface and a second surface; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; Contacting the fluid with a filter element comprising an outlet in fluid communication with the second surface. Flowing the molten polymer through the plurality of orifices to form a filament;
Thinning the filaments into fibers;
Directing a stream of sorbent particles between the filaments or fibers;
Collecting the fibers and sorbent particles as a nonwoven web to form a porous article;
And positioning the porous article in a liquid impermeable housing. The method of claim 28, further comprising pressing the nonwoven web by calendering, heating, or applying pressure to form a compressed web having a Gurley time of 2 seconds or less. The method of claim 28, further comprising attaching a plurality of nonwoven webs adjacent to each other to form a porous article. The method of claim 28, further comprising winding the nonwoven web prior to placing the nonwoven web in the housing. The method of claim 28, further comprising controlling the rheology of the fibers. A plurality of porous layers wound to form a porous article and comprising a web of freestanding nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web;
A liquid impermeable housing surrounding the porous article;
An inlet in fluid communication with the first surface;
A filter element comprising an outlet in fluid communication with the second surface. The filter element of claim 33, wherein the plurality of porous layers are fused together. The filter element of claim 33, wherein the plurality of porous layers are separate composite layers. 34. The filter element of claim 33, wherein the sorbent particles comprise activated carbon, diatomaceous earth, ion exchange resins, metal ion exchange sorbents, activated alumina, antimicrobial compounds, acid gas adsorbents, arsenic reducing materials, iodide resins, or combinations thereof. . 34. The filter element of claim 33, further comprising a core surrounded by the web. The filter element of claim 33, wherein the web has a sorbent particle density in the range of 0.20 to 0.5 g / cc. 34. The filter element of claim 33, wherein the polymer fiber comprises polypropylene. The filter element of claim 33, wherein the polymer fiber comprises a metallocene-catalyzed polyolefin. 41. The filter element of claim 40, wherein the polyolefin is polypropylene. 40. The filter element of claim 39, wherein the polypropylene has a polymer melt flow index in the range of 30-1500. 34. The filter element of claim 33 wherein the first plurality of layers comprise polymer fibers having a first effective fiber diameter and the second plurality of layers comprise polymer fibers having a second effective fiber diameter. 34. The filter element of claim 33, wherein the polymer fibers comprise a mixture of effective fiber diameters. 34. The filter element of claim 33, wherein the sorbent particles are present at a first density in the first plurality of layers and at a second density in the second plurality of layers. 34. The filter element of claim 33 wherein the first plurality of layers comprise a first sorbent and the second plurality of layers comprise a second sorbent. 34. The filter element of claim 33 wherein the first plurality of layers comprise particles having a first average size and the second plurality of layers comprise particles having a second average size. 34. The filter element of claim 33, wherein the filter element has a sorbent density gradient in the axial configuration. 34. The filter element of claim 33, wherein the filter element has a sorbent density gradient in the radial configuration. 34. The filter element of claim 33, further comprising a plurality of layers of a second web of freestanding nonwoven polymer fibers substantially free of sorbent particles. A first plurality of porous layers wound to form a porous article and comprising a first web of self-supporting nonwoven polypropylene fibers and a plurality of carbon particles captured within the first web;
A liquid impermeable housing surrounding the porous article;
An inlet in fluid communication with the first surface;
A filter element comprising an outlet in fluid communication with the second surface. The filter element of claim 51, wherein the porous article further comprises a second plurality of porous layers, the porous layer comprising a second web of self-supporting nonwoven polypropylene fibers and an ion exchange resin trapped within the second web. A plurality of porous layers wound to form a porous article and comprising a web of freestanding nonwoven polymeric fibers and a plurality of sorbent particles trapped within the web; A liquid impermeable housing surrounding the porous article; An inlet in fluid communication with the first surface; Contacting the fluid with a filter element comprising an outlet in fluid communication with the second surface. Flowing the molten polymer through the plurality of orifices to form a filament;
Thinning the filaments into fibers;
Directing a stream of sorbent particles between the filaments or fibers;
Collecting the fibers and sorbent particles on the spindle as a nonwoven web to form a porous article;
And positioning the porous article in a liquid impermeable housing. 55. The method of claim 54, further comprising forming a first plurality of layers comprising polymer fibers having a first effective fiber diameter and a second plurality of layers comprising polymer fibers having a second effective fiber diameter. Way. 55. The method of claim 54, further comprising providing sorbent particles at a first density in the first plurality of layers and at a second density in the second plurality of layers. 55. The method of claim 54, further comprising providing a first plurality of layers with a first sorbent and a second plurality of layers with a second sorbent. 55. The method of claim 54, further comprising controlling the rheology of the fibers.

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