EP1771234A1 - Gas porous polymer filter and methods of making it - Google Patents
Gas porous polymer filter and methods of making itInfo
- Publication number
- EP1771234A1 EP1771234A1 EP04821580A EP04821580A EP1771234A1 EP 1771234 A1 EP1771234 A1 EP 1771234A1 EP 04821580 A EP04821580 A EP 04821580A EP 04821580 A EP04821580 A EP 04821580A EP 1771234 A1 EP1771234 A1 EP 1771234A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- polymer particles
- microns
- activated carbon
- filter
- matrix
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D39/00—Filtering material for liquid or gaseous fluids
- B01D39/14—Other self-supporting filtering material ; Other filtering material
- B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
- B01D39/2055—Carbonaceous material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D39/00—Filtering material for liquid or gaseous fluids
- B01D39/14—Other self-supporting filtering material ; Other filtering material
- B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
- B01D39/1638—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being particulate
- B01D39/1653—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being particulate of synthetic origin
- B01D39/1661—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being particulate of synthetic origin sintered or bonded
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D39/00—Filtering material for liquid or gaseous fluids
- B01D39/14—Other self-supporting filtering material ; Other filtering material
- B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
- B01D39/2055—Carbonaceous material
- B01D39/2058—Carbonaceous material the material being particulate
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D39/00—Filtering material for liquid or gaseous fluids
- B01D39/14—Other self-supporting filtering material ; Other filtering material
- B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
- B01D39/2055—Carbonaceous material
- B01D39/2058—Carbonaceous material the material being particulate
- B01D39/2062—Bonded, e.g. activated carbon blocks
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
- B01J20/041—Oxides or hydroxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/04—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium
- B01J20/046—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising compounds of alkali metals, alkaline earth metals or magnesium containing halogens, e.g. halides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
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- B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
- B01J20/26—Synthetic macromolecular compounds
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- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28002—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their physical properties
- B01J20/28004—Sorbent size or size distribution, e.g. particle size
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/28016—Particle form
- B01J20/28019—Spherical, ellipsoidal or cylindrical
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- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/28023—Fibres or filaments
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
- B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
- B01J20/28026—Particles within, immobilised, dispersed, entrapped in or on a matrix, e.g. a resin
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/32—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating
- B01J20/3231—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating characterised by the coating or impregnating layer
- B01J20/3234—Inorganic material layers
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- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/30—Processes for preparing, regenerating, or reactivating
- B01J20/32—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating
- B01J20/3231—Impregnating or coating ; Solid sorbent compositions obtained from processes involving impregnating or coating characterised by the coating or impregnating layer
- B01J20/3234—Inorganic material layers
- B01J20/3236—Inorganic material layers containing metal, other than zeolites, e.g. oxides, hydroxides, sulphides or salts
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/283—Treatment of water, waste water, or sewage by sorption using coal, charred products, or inorganic mixtures containing them
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
- B01D2239/04—Additives and treatments of the filtering material
- B01D2239/0407—Additives and treatments of the filtering material comprising particulate additives, e.g. adsorbents
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
- B01D2239/04—Additives and treatments of the filtering material
- B01D2239/0442—Antimicrobial, antibacterial, antifungal additives
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
- B01D2239/04—Additives and treatments of the filtering material
- B01D2239/0464—Impregnants
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
- B01D2239/12—Special parameters characterising the filtering material
- B01D2239/1241—Particle diameter
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01J2220/00—Aspects relating to sorbent materials
- B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
- B01J2220/46—Materials comprising a mixture of inorganic and organic materials
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/281—Treatment of water, waste water, or sewage by sorption using inorganic sorbents
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/28—Treatment of water, waste water, or sewage by sorption
- C02F1/288—Treatment of water, waste water, or sewage by sorption using composite sorbents, e.g. coated, impregnated, multi-layered
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/68—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
- C02F1/683—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water by addition of complex-forming compounds
Definitions
- the present invention relates to filtration devices, novel methods for the production of the same and methods of use. More specifically, the present invention relates to a methodology of vibrating and then sintering polymers having distinct morphologies to achieve a structural filtration matrix, which is also capable of accommodating various compounds for the removal, reduction or adsorption of undesirable contaminants in liquids and gases, most notably water and air.
- the filtration of fluids may be accomplished through a variety of technologies, the selection of which is often determined by the contaminant or contaminants that are being targeted for removal or reduction. Particulates are best removed through a process known as depth filtration. The filter collects and holds any dirt or sediment within its matrix.
- Dissolved organic contaminants appearing on a molecular level may be removed through adsorption or, in the case of minerals and metals, through ion exchange.
- Very small contaminants, including microorganisms down to sub-micron sizes often require some form of membrane technology in which the pores in the membrane are configured to be smaller than the target contaminant; or they can be deactivated in some manner.
- Contaminants in drinking water may be broken down into four groups: (i) turbidity and particulates; (ii) organic based chemicals and pesticides; (iii) inorganic matter such as dissolved heavy metals that pose a health risk such as lead; and minerals; (iv) microorganisms such as protozoan parasites, bacteria and viruses.
- ⁇ DE - 21 53/0001 - 207293 v2 particles are then sintered in a mold.
- the process known more specifically as porous plastics, involves taking the mold filled with the plastic material up to a temperature where the particles soften but do not melt, such that all of the particles stick to one another. The mold is then brought back to ambient temperature and the material is ejected from the mold. The finished part is at the same time solid and self-supporting while being porous to fluids. Any plastic that can be ground into a granular form can be used; and some polyethylene polymers are produced in a powder form. Finer particles create a matrix of smaller spaces between the plastic particles which are known as voids or pores.
- Filtering materials including but not limited to activated carbon, may be added to enhance the filtration of a specific contaminant.
- the process of blending into and holding within the matrix of the polymeric material other filtering compounds requires that the total surface area of the polymer be greater than the total surface area that the added materials take up, such that there is sufficient adhesion.
- the resulting part is durable and self-supporting.
- both the polymeric material and the filtration compounds selected generally share a similar bulk density and particle size the preferred ratio by weight for most filtration applications provides that at least 50% to 60% of the filter by weight be polymeric particles. In this process there is no force, compression nor pressure applied to the materials before or during processing, such that both the polymer particles and the filtering materials remain essentially in tact (i.e.
- the fluid being filtered flows through the porous matrix where it is forced into contact with the adsorbents or other filtering materials.
- This filtering technique known as tortuous path filtration differs from what is known as absolute filtration.
- the size of the median diameter of the pores within the porous plastic filter determine how much of any given contaminant by size will be allowed to pass through the filter matrix. These pores cannot be made to a consistent single size and generally range from large to small, with the filter being measured by its median pore diameter (MPD) as determined by a mercury poresimiter analysis.
- MPD median pore diameter
- the median pore diameter may be manipulated, as stated above, to be larger or smaller by manipulating the size of the particles that comprise it. This includes both the particle sizes of the plastic granules or powders as well as any material being blended into it.
- An alternative method of filter making is known as carbon block technology.
- Carbon blocks are molded granular activated carbon particles.
- the origin came from the need to improve upon the use of loose bed carbon particles that have been utilized to remove organic contaminants from water since Roman times.
- loose bed activated carbon filters lack performance in specific areas and, as a practical matter, take up too much space for many point-of-use applications.
- thermoplastic material known as the binder
- the binder in a general ratio of about 4 parts granular activated carbon to 1 part thermoplastic material.
- the material is thoroughly blended together, poured into a cylinder shaped mold and compressed so as to compact the blended material as much as possible.
- the material is then heated to a point where the binder either softens or melts to cause all of the carbon particles to adhere to one another.
- the adhesion process uses only a small amount of binder in a ratio to activated carbon granules, which is aided by the compression that is applied to the two materials during processing.
- the finished part takes on the form of a solid cylinder block comprised of carbon particles, which is self-supporting while being porous to most fluids.
- the cylinders invariably are tube shaped such that there is a core and a wall thickness. Water is directed to flow radially from the outside diameter (OD) surface of the tube to the inside diameter (ID) and then out one end of the core.
- OD outside diameter
- ID inside diameter
- the ability to bond carbon particles together in a fixed bed enables carbon filters to use finer carbon particles than those traditionally used in loose bed filtering methods.
- the use of finer particles in turn increased the amount of available surface area of the adsorbent activated carbon, while compression of the particles during processing increased the density of carbon particles.
- 5,019,311 disclosed an alternative method of carbon block manufacture in which the adsorbent activated carbon may be blended with a combination of very low melt temperature binders and driven through an extrusion tube by an auger. The blended material is compressed as it is conveyed into the extrusion tube, then heated and quickly cooled to produce an extruded carbon block.
- carbon block methodologies have certain limitations which the current invention overcomes. Carbon blocks are limited to the use of only one primary filtering material: activated carbon granules, without which there is no filter. Further limitations include the lack of depth filtration and durability. Carbon block filters exhibit a high pressure drop as a result of the compression used during processing. Fluid filters made using the current invention's methodology combined with specific polymers represent a major departure from prior art filter making methods.
- the current fluid filter invention may incorporate any filtering material without 3
- the filtration device of the present invention relies on materials and methodologies that achieve the formation of a structural matrix that may later accommodate the addition of a wide spectrum of filtration materials.
- the filter of the present invention relies on (i) a unique method of processing to achieve maximum, uniform density of materials, (ii) polymeric materials having an exceptionally small particle size with a distinct morphology that is retained throughout and (iii) a polymeric matrix that forms the primary structure of the filter.
- the method of processing involves the vigorous vibration of powdered filtering materials and polymer until they are firmly compacted into a given space such as a mold cavity.
- ⁇ DE - 21 53/0001 - 207293 v2 enables a wider range of filtering materials that can be used with it.
- Filtering materials in the form of very fine powders exhibit greater surface area than coarser granules.
- one common objective is to create a matrix that provides the maximum amount of available surface area of a given contaminant filtering material in the finished filter.
- the filtering materials are bonded onto a porous plastic matrix that is equal to or greater in overall surface area than the filtration materials being added, i place of an external binder whose sole function is limited to the adhesion of the activated carbon granules
- the polymeric material in the current invention may be formulated to determine such characteristics as structural integrity, median pore diameter of the filter matrix, amount of depth filtration, density of filtering materials and pressure drop. This polymeric material in the form of a very fine powder adheres to itself during processing and will not deform when heated.
- a tortuous path filter may be rated by the median pore diameter (MPD) within the filter's matrix.
- MPD median pore diameter
- the theory of absolute micron rating is that any particle larger than the largest pore size in the filter's matrix will be rejected physically.
- tortuous path filtration the particulate passes through a maze of multi-directional pores of varying pore diameters in a range that may be both larger and smaller than the particulate. Randomly, the particulate eventually becomes trapped within a pore that is smaller and is retained, while the liquid or gas being filtered easily passes on through. The chances of one particle making it through the labyrinthine matrix are small.
- There are many advantages to a properly developed tortuous path matrix one of which is excellent depth filtration. Filters that rely on absolute filtration reject particulates on the exterior surface of the filter, where they accumulate and eventually clog the filter. Filters that rely on tortuosity hold particulates within the filter matrix, not its surface.
- Figure 1 is a photomicrograph demonstrating the morphology of the first base polymeric material, referred to as PMX CF-1.
- Figure 2 is a photomicrograph demonstrating the morphology of the second polymeric material, referred to as PMX CF-2.
- Figure 3 is a graph of the particle distribution of the base material shown in Figure 1 demonstrating that the average micron diameter is approximately 37 microns.
- Figure 4 is a graph of the particle distribution of the material shown in Figure 2 demonstrating that the average micron diameter is approximately 60 microns.
- Figure 5 is a graph of a laser particle analysis of the particle distribution density of filtering adsorbent material used in one of the preferred embodiments of the present invention.
- the filtration device of the present invention relies on (i) a unique method of processing to achieve maximum density of materials with uniform particle distribution, (ii) a combination of polymeric materials having distinctly different morphologies to create a formed, structural filtration matrix and (iii) a polymeric material having a very small micron diameter that enhances the use of finely powdered filtering compounds.
- These compounds may include adsorbents, such as but not limited to granular and powdered activated carbon, metal ion exchange zeolite sorbents such as Engelhard' s ATS, activated aluminas such as
- a structural filtration matrix accommodates the presence of filtering compounds, which may be formulated to a specific task such as targeting one contaminant only or one group of contaminants, such as for example heavy metals; or it may be formulated to filter out a broad spectrum of contaminants from various contaminant groups.
- filtering compounds which may be formulated to a specific task such as targeting one contaminant only or one group of contaminants, such as for example heavy metals; or it may be formulated to filter out a broad spectrum of contaminants from various contaminant groups.
- the ability to incorporate any filtering material of any particle size or any combination thereof into the polymeric matrix enables greater flexibility in formulating a filter to a given task.
- the method of the present invention utilizes vibration rather than compression of the materials to be sintered. Vibration optimizes how all of the materials fill the mold completely without force or deformation of the particles.
- the mold receiving the material being processed is therefore vibrated as the blended material is gradually conveyed into the mold. Once the mold cavity or cavities has been vibrated to a point where it will hold no more material, it is free sintered such that it is heated to a point where all of the polymeric materials soften on the surface and stick to the surrounding particles and is then returned to ambient temperature.
- the base polymeric materials comprising the filter matrix of the present invention are two very fine polymer powders in the 30 to 60 mean particle size range, respectively, which become tacky at elevated temperatures yet without losing their distinct morphologies.
- the finished part which is now self- supporting, exhibits a complex internal matrix comprised of millions of minute, interconnected, multi-directional pores of varying diameters forming a tortuous path obstacle to the through flow of contaminants in fluids.
- the filter may be formed using only one or both of the polymer powders, and may include any filtering material that remains stable at the processing temperature of from about 275 F to 375 F.
- polymers are specifically characterized, for the purpose and resulting success of the current invention, as follows: (i) they each have individual morphologies that contribute to the surface area, durability, density and tortuosity of the filter's matrix; (ii) they will soften and adhere to each other or to other materials when heated to a critical temperature; (iii) during processing they retain their respective morphologies; and (iv) their respective micron diameters are critical to the enabling of the use of the materials in the preferred embodiments.
- PMX CF-1 Figure 1 has a unique morphology, much like popcorn, in which the surface is convoluted and the particle itself is perforated, and a bulk density of 0.25 to 0.30 g/cm 3 .
- This unique morphology provides a considerable increase in surface area of the particle as compared to PMX CF-2 ( Figure 2), which has a traditional, spherical shape and a bulk density of 0.40 to 0.48 g/cm 3 .
- Each particle's morphology provides a different characteristic, as does its bulk density and average particle size.
- PMX CF-1 's expanded surface area and irregular shape creates a very strong, somewhat elastic, durable part when processed according to the methodology disclosed herein.
- the polymer itself is vented such that fluids flow both through and around it. It easily bonds to very fine powders that are comparable to or smaller in particle size to itself; but it will also bond well to much larger particles where necessary.
- the PMX CF-2 material's main attributes are greater density of materials and an elevated pressure drop.
- a filter made solely of PMX CF-2 and filtering materials requires a ratio of more polymer-to-filtering material, generally in a ratio of about 3:2 by weight, since PMX CF-2 has less surface area. As more material is added the resulting part becomes weaker. This weakness is a result of the polymer's spherical morphology, since spheres provide fewer points of contact for adhesion in comparison to the irregular shaped particles of PMX CF-1.
- the two PMX materials are blended in differing ratios to one another and other filtering materials to achieve a finished filter part that acquires qualities of both polymeric materials.
- the method of the present invention also teaches the benefits and superiority of creating a polymeric filter matrix from the two PMX polymers, whose morphology and size enable finer, powdered adsorbent materials to be used to enhance performance.
- the ones selected for the preferred embodiment are PMX CF-1 and PMX CF-2, manufactured by Ticona, a division of Celanese, located at 90 Morris Avenue, Summit, NJ 07901, USA.
- polymers available from other manufacturers of very high and ultra high molecular weight polymers that are comparable in particle size, bulk density, morphology and a molecular weight of from about 750,000 to 3,000,000 may also be used. While the two polymers have the same melt flow characteristics, the two PMX polymer particles differ from each other in morphology, bulk density and average micron size.
- PMX CF-1 is shown to have an average micron diameter of about 30 to 40 microns, with a total range from 10 microns to 100 microns.
- PMX CF-2 is shown to have an average micron diameter of 55 to 65 microns, with a particle distribution range from 10 to 180 microns.
- the PMX CF-2 powder may be screened through a sieve so that its average micron diameter is adjusted down to about 30 to 40 microns.
- any commercially available polymer of similar characteristics with the desired micron size and morphology would suffice.
- the morphology is significant since PMX CF-1 exhibits a greater amount of surface area, a very small micron diameter and an irregular shape.
- the unusually small micron size combined with the particle's unique shape as shown in Figure 1 allow the polymer particle to bond more thoroughly to other particles during processing since there are more contact points than a typical spherical shaped polymer particle, such as the PMX CF-2, as shown in Figure 2 material.
- the expanded surface area enables the particle to accommodate more finely powdered filtering compounds that bond to it during processing.
- the small micron size adapts more easily to other materials of any particle size or distribution range, but especially well to particles of a similar size or smaller.
- PMX CF-1 polymer particle Smaller particles become trapped within the irregular surface of the PMX CF-1 polymer particle itself without decreasing its ability to adhere to other adsorbent materials during processing. This characteristic is specific to only PMX CF-1. This is advantageous since, as a rule, the finer an adsorbent material is powdered the better it will perform in filtration since more of its surface area is exposed to passing contaminants.
- One characteristic of the PMX CF-1 polymer is that when it is blended with granular or powdered additives such as the aforementioned compounds and/or adsorbents, it is very durable with lesser density and the highest amount of depth filtration capability. Depth filtration is the ability to trap and hold suspended particulates from a fluid stream. As PMX CF-2 is formulated into the material, the parts gain density with greater part weight, while the pressure drop increases slightly. The increased 9
- ⁇ DE - 21953/0001 - 207293 v2 pressure drop does not actually denote a smaller median pore size; rather, it results from the replacement of the CF-1 material, which is itself porous to fluids, by the CF-2 polymer, whose spherical shape is non-porous.. As fluids flow through the filter matrix the CF-2 material has reduced the total pore volume within the matrix.
- a filter may be formulated to achieve very specific goals. For example, where a fluid contains both particulates and contaminated with dissolved organics such as for example, an unacceptable level of pesticidal residue, the objective may be depth filtration in conjunction with an adsorbent such as activated carbon.
- the solution might be a filter comprising about 50% PMX CF-1 and 50% finely powdered activated carbon particles such as those shown in Figure 5, or a more coarse, granular activated carbon particle size ranging from about 45 to 180 microns.
- the filter may be made to have greater density by replacing some of the CF-1 with CF-2. hi this case the over all filter weight increases.
- the actual ratio between the two polymers would subsequently be determined by the desired flow rate of the fluid being filtered and the actual geometry of the filter part when molded.
- the process may be repeated continuously with predictable filter performance so long as the added filtering materials remain within certain tolerances such as mean particle size, particle distribution density, bulk density and moisture content.
- Blinding simply means that an exchange site on the surface of a filtering material such as an adsorbent or an ion exchange material is interrupted by a particle of binder such that it does not come into contact with the fluid stream.
- a filtering material such as an adsorbent or an ion exchange material
- the filtering materials are forcibly imbedded into the binding material under heat and pressure.
- Such binders deform under pressure, lose their morphology and blind off a portion of the filtering material.
- Very low melt temperature binders simply liquefy and absorb very fine powders and blind larger particles, reducing the amount of available surface area. In the method of the current invention very fine powders bond to the massive surface created by the polymeric structural filtration matrix. Where exceptional filtration of dissolved organics and metals in a liquid such as water is desirable, 10
- the use of such finely pulverized filtering compounds is an important achievement because they exhibit more available surface area, which in turn increases the contact time between the filtering material and the contaminant.
- the novelty of the filter of the present invention relies upon the formulation, interrelationship and use of the two polymers as depicted in Figure 1 and in Figure 2 when processed using the aforementioned vibration sintering method. When used alone each polymer creates a filter with certain characteristics that differ from each other. By combining the two polymers in a given formulation with or without the addition of filtering materials, the finished filter takes on attributes of both polymers.
- filtering compounds Most applications in filtering fluids require the use of specific filtering compounds.
- activated carbon Known as an adsorbent, activated carbon will take up and hold on its surface dissolved organic contaminants such as pesticidal residues, organic vapors, etc. It will also eliminate chlorine in drinking water in a process known as reduction.
- Other filtering materials work on the principle of ion exchange. For example, heavy metals such as lead may be removed from drinking water using a metal ion exchange zeolite sorbents or activated aluminas.
- filtering materials include antimicrobials. These are typically silver or halogen based products that discourage the growth of bacteria and other microorganisms. Filtering compounds that are commonly used in filtering gases and liquids are available in powder form and a partial listing of filtering compounds that may be used in the present invention are listed below in Table I.
- the average particle size of the filtering material determines how much of its available surface area comes into contact with the fluid being filtered, such that the smaller the particle the greater the available surface area.
- 1 gram of activated carbon is capable of having up to 1500 m 2 of surface area.
- Activated carbon is available in granular form or it may be pulverized.
- particles of activated carbon with a mean particle diameter of only 22 microns may be used.
- the typical filter contains 50% or more polymeric material in the form of one or both of the PMX CF-1 and PMX CF-2 polymers. Because of this the total surface area for bonding is greater and the particle size of CF-1 material combined with its unique morphology creates a massively greater surface area than traditional morphologies.
- the CF-2 polymer's spherical morphology is unique because of its average size of only 60 microns, which gives it greater surface area.
- While one of the preferred embodiments calls for a powdered activated carbon as referenced above and further evidenced by a laser particle analysis seen on Table II, there are other carbon particle distributions which are used to create different features.
- the objective is to optimize the filtration of dissolved organic based contaminants, the greater amount of available surface area found in powdered activated carbon yields superior results.
- coarser mesh carbons ranging from 45 to 180 microns render a more rounded filter, which performs very well with a more open pore structure that has greater depth filtration and only a very modest pressure drop.
- the most common filtering materials for heavy metal removal are very fine powders which take up large amounts of surface area of the chosen polymers.
- a particle size range of 45 to 180 microns can be preferable because the larger particles of activated carbon take up less surface area of polymer, thereby balancing the formula so that the filter adequately removes both heavy metals and dissolved organic contaminants.
- Activated carbon for example, is readily available in micron size ranges starting at 1000 microns and lower and these may be used in combination with the PMX CF-1 and PMX CF-2 polymers to create a very open pore structure with good depth filtration and moderate reduction of organics, such as in pre-filtration applications.
- Non carbonaceous materials very often are not available in powder from.
- the PMX CF-1 and PMX CF-2 polymers will accommodate particles as large as 1000 microns.
- KDF a fluid treatment compound comprised of zinc and copper is commonly used for the removal of heavy metals and chlorine.
- KDF is made of relatively coarse metallic particles, which bond very well to the PMX CF-1 and PMX CF-2 polymers, with the former performing especially well due to its superior bonding capability and flow through characteristics. While the respective morphologies of these two polymers is important in the development of a filter with unique characteristics, their micron size and particle distribution enables the filter to accommodate both granular as well as finely powdered compounds of similar or smaller median particle diameters.
- the objective is to create a very high performance finished filter that is durable, exhibits good depth filtration, has adequate density of materials to give it greater capacity, and an acceptable pressure drop.
- the PMX CF-1 material exhibits greater surface area, superior bonding capability, and is highly durable with a relatively slight pressure drop.
- a filter made with PMX CF-1 provides the maximum amount of depth filtration and tortuosity when formed by itself or in conjunction with filtering materials.
- the PMX CF-2 material with its spherical morphology creates a denser matrix such that more material fills the same amount of space. This creates a higher pressure drop as compared to PMX CF-1.
- a starting point in the development of a formula is generally a filter which contains about equal amounts of each polymer, which is then blended with from about 0.025 % up to 55 % by weight of the chosen filtering material. Certain variables control the actual formula.
- the finer the filtering material to be added the greater surface area of polymer will be required since finer particles cover a greater surface.
- the geometry of the part may be delicate or it may be strong.
- a part with a wall thickness of 0.125" 14 ⁇ DE - 21953/0001 - 207293 v2 requires the strength of the polymeric material to be self supporting, while a part with a wall thickness of 0.500" becomes self supporting with less polymeric material content.
- delicate parts favor a greater amount of PMX CF-1 due to its durability, whereas strong parts may only require a lesser amount of PMX CF-1 and can be primarily made of PMX CF-2.
- the added filtering material may be as small as 0.025% by weight of the total part up to 55% by weight, which will depend on the filtering objective.
- the part may be comprised of only one of the two polymers, or a blend of the two in which the ratio may be any given amount of one to the other.
- This wide spectrum of possibilities in formulations allows the filter to be formulated to the particular characteristics of the materials. This is significant because various filtering materials available in powder form will vary in mean particle size, particle distribution density, and bulk density. To rely on only one formula would limit the full utilization of filtering materials.
- the use of adsorbent materials such as activated carbon with a coarser particle distribution is less efficacious in the removal of dissolved organic contaminants.
- Such coarser materials open up the median pore diameter and provide less surface area to be exposed to the liquid or gas flowing through the filter's matrix.
- the starting point may be a blend of polymers to filtering material where the polymer is PMX CF-1 by itself in a ratio of 1 part polymer to 3 or 4 parts granular activated carbon.
- the PMX CF-1 in this instance gives the final part sufficient strength and durability to be self supporting as a result of its greater adhesion characteristics.
- the reduced surface area of the filtering material permits a reduced amount of PMX CF-1 used to mold the part together.
- ⁇ DE - 21953/0001 - 207293 v2 small particle size of the PMX polymer particles plays a key part in the invention's novelty.
- a larger polymer particle with a similar morphology has less surface area and processes poorly with finer powders.
- the next step is the exact method of processing. Once a formula has been established to exhibit the desired characteristics in the finished filter, it must be processed in a specific manner.
- the materials selected are blended together so that the final material is homogeneous and free of clumps.
- a ribbon blender or the like is generally capable of accomplishing this.
- the blended material is then conveyed from the blender to a mold that may have one or more cavities in the mold. The cavity geometry will determine the final shape of the finished part.
- This form may be any given shape including a square or rectangular cube, a disk, a flat panel, a cup, a rod or a cylinder that is solid or a cylinder that has a core, being open at only one end or open at both ends.
- the material can also be formed into a continuous sheet material with a thickness down to 1mm.
- the only limitation to the shape of the part is that it be able to be removed from the mold after processing.
- the mold is simultaneously vibrated using any standard mechanical industrial vibrator available. Commercially available vibrators will shake in an up and down motion or they will swirl the material as they vibrate, or both.
- the degree of vibration may be increased or decreased depending on any number of variables including the overall mass of the mold by weight, the size of the finished filter parts, as well as the aspect ratio of the parts where the length is greater than the width. Vibration should begin before the powder is conveyed into the cavity or where particles may migrate away from each other and separate in the mold, vibration may be commenced after the cavity begins to fill up with the material, hi some applications, learned through experimentation, no vibration may be required. Shorter and longer vibration cycles yield differing results, which are even further differentiated by the characteristics of the cavities depth and width.
- the objective of vibration is two-fold: (1) to gently rid the powdered materials of air pockets causing void spaces between particles without disrupting or crushing the particles being vibrated; and (2) to maximize the amount of total powder that will compact into the mold cavity without force or compression by causing them to shift and rotate until they fit together with other particles.
- a shorter vibration cycle may cause less compaction while greater vibration may cause unwanted particle separation where finer particles migrate away from larger particles.
- This problem is of particular concern where the polymeric material is primarily spherical. Abandoning the vibration of the material prior to completely filling the mold is unadvisable since the last material added may have a different particle density; over vibration will eventually cause different material particles to migrate away from each other. There are exceptions, such as when it is not desirable to have 16
- the mold At the end of the vibration cycle, the mold must be covered with a cover plate and is heated to a temperature such that the polymers will become sticky enough to adhere to other polymer particles or a combination of other polymer particles and filtering compounds. While PMX CF-1 and PMX CF-2, in the preferred embodiment, have a molecular weight of about 3,000,000 and will not lose their original morphology if heated beyond their softening point, lower molecular weight polymers in the 750,000 and higher range and with similar morphologies may be heated to a softening point and used as well.
- the filter will have filter characteristics that screen out physical contaminants or it may also be used to disperse a gas into minute bubbles. It can also be formulated to remove larger parasites such as Giardia and other protozoans. In water filtration, for example, there are specific applications where it is desirable to remove such microorganisms without the use of activated carbons, which are known to breed bacteria. As discussed above, the performance of the filter to remove a specific contaminant will depend on the filtering compound chosen. Activated carbon is recognized as an adsorbent of organic based contaminants ranging from dissolved organic matter to chemicals and pesticides.
- titanium metal ion exchange zeolites such as Engelhard Mineral's ATSTM Sorbent, and activated aluminas such as Selecto Scientific's AlusilTM have been developed to remove lead and heavy metals from a liquid such as drinking water.
- Silver ions are known to inhibit the growth of pathogens such as E. coli bacteria and are available in a variety of forms that include synthetic zeolites where the sodium ions have been exchanged for silver and zinc ions.
- One such popular synthetic zeolite is AgionTM, manufactured in Japan by Sinanen and distributed by Agion Technologies. Certain rules determine more desirable results. Most notable is the relationship between the total surface area of the polymer matrix and the amount of surface area taken up by the filtering compound that bond to the matrix during processing. A consistently durable, finished part will be formulated such 17
- the added filtering material does not take up more polymeric surface area than is available the finished part will become self-supporting.
- a powdered material of any particle size may be added, or a material with a particle distribution range that includes sub-micron size particles may be successfully employed. However, a small amount of very fine powders under 5 microns will quickly coat the entire surface of the polymer matrix and will thus limit the total amount that can be used without loss of structure.
- particles of polymer and filtering compounds of equal size and general bulk density may as a rule are blended in equal amounts by weight where at least 10% or more of the total polymeric material is PMX CF-1.
- PMX CF-1 Filtering compounds that are smaller in particle size than the basic polymer material are not only accommodated by the greater surface area of PMX CF-1 because of the polymer size, but the unusual morphology takes this concept to an even higher level of performance.
- Another feature of the PMX CF-1 material is that it is vented with microscopic channels that course through the interior of the particle. This feature further enhances the flow through characteristics of the filter, including a reduced pressure drop.
- the unique morphology of PMX CF-1 allows very fine particles of filtering material to bond to the surface of the larger polymer particles, while filtering compounds that are equal to or larger than the polymer become trapped within the pores or void spaces of the filter matrix. In this way the non-polymeric compound is integral to the filtering but not to the structure.
- filters to exhibit a number of qualities that differentiate the invention from prior art. These may be summarized as follows: Impact resistance. Since the filters are comprised of from about 50% to 100% of a basic material comprised of the PMX material formulations as described above, they are durable and resist cracking or breaking on impact. Wherever a filter must be unbreakable, such as portable applications in the wilderness or military uses, the filters may be formulated to achieve that specific goal while still achieving superior filtration. 18
- ⁇ DE - 21953/0001 - 207293 v2 Pressure Drop, or Delta P is the variation in water pressure before and directly after passing through a given filter. The drop is determined by subtracting the latter from the former such that if the pressure going into the filter is 60 psi and then 50 psi coming out, the pressure drop is 10 psi; and so on. Pressure drop is unavoidable. However, a filter demonstrating the least amount of pressure drop without corresponding loss of performance is preferable. This advantage in the current invention is owing to the internal filter matrix that contains more flow through channels than a compressed filter. The greater number of channels is a result of the polymer characteristics combined with the alternative method of processing.
- Filters using absolute micron filtration exhibit corresponding increases in pressure drop as the diameter of the pores decreases. Therefore a superior method of filtration is through tortuosity.
- the number of pathways through a given filter matrix is greater than a similar filter created through the compression of particles together, especially where the compression is in the range of 30%.
- a filter using 100% PMX CF-1 was tested for air permeability against filters in which PMX CF-2 was blended. The first blend was 90% PMX CF-1 to 10% PMX CF-2. The pressure drop increased slightly. However, at 80% PMX CF-1 to 20% PMX CF-2 there was a distinct and measurable increase in pressure drop.
- x the micron rating
- the benefit to tortuous path filtration with its accompanying depth filtration capability is that it filters within the matrix rather than on the filter's surface, thus avoiding premature clogging. Molding capability is another valuable attribute of the invention.
- the durability allows parts to be shaped into any form. In liquid filtration, today most methods relying on prior art are manufactured solely in the form of a cylinder shaped filter in which the liquid is directed to flow in radial direction from the outside diameter of the cylinder into the inside diameter of the cylinder, passing through a wall thickness of bound carbon particles.
- the cylinder shape of the parts is limiting, as well as the other limiting feature that the finished parts will splinter and crack easily.
- the invention provides for parts that are made of a durable plastic which may be formed into any shape, even with all thickness down to about 3000 microns where adsorbent are used.
- the parts may be formed into disks, rods, cups, cylinders or closed end cylinders.
- the availability of the forms expands product development potential where the finished filtering device is not bound to a cylindrical filter shape. Cylinders that are tubes, open at both ends, may be closed at one end during processing rather than having to be closed off with an end cap. This reduces in some applications manufacturing costs and increases speed of assembly of the filter into a finished device or housing.
- OV Organic Vapor
- OV masks are constructed of loose granular activated carbon particles in the general range of 250 microns and larger. These are packed tightly into a canister and air is drawn through them to filter out organic vapors.
- No prior art applications have been able to reach the demands of air filtration without using an external source of pressure because the pressure drop is too high, hi a respirator such as an OV mask only one's breath is used to draw in the air through the carbon.
- Still another application that relies on this special molding capability is in the adsorption of organic vapors combined with humidity regulation.
- Activated carbon is an excellent regulator of humidity. The higher the activity of the carbon the better it will absorb moisture from a gas such as air.
- High activity activated carbons such as those having a Carbon Tetrachloride Number (CTC #) of +95 are most preferable where very high performance in is a must. However, even standard carbons with a CTC number of +65 are more than adequate for most filtration applications.
- Low humidity levels below a relative humidity (RH) of 40 will allow the humidity to pass over a bed of activated carbon without reduction. As the humidity increases over 40 RH, the humidity is removed from the passing air. This quality of activated carbon has been adapted and used in regulating the RH in delicate instruments.
- RH relative humidity
- ⁇ DE - 21953/0001 - 207293 v2 particular is controlling the both organic vapors and RH inside of a computer disk drive, which is vulnerable to both.
- one filter is capable of removing trace amounts of organic gases from incoming air, while maintaining humidity levels that are either not too high or not too low.
- the presence of very minute amounts of acid gases, for example, has proven to corrode the heads on computer disk drives, as has excessive humidity levels.
- Higher performance The use of finely powdered adsorbents such as activated carbon powders, zeolites, activated aluminas, antimicrobials, etc.
- Filter A was taken from a commercially available source. The manufacturer determined that given the factors of flow and capacity that 18% of the filter by weight was Engelhard' s ATS. The filter weighed 150 grams. Filter B was made to match the same dimensions of Length, Outside Diameter (OD) and Inside Diameter (ID). Filter B weighted 112 grams and was formulated with 10% by weight of ATS. The resulting two filters then featured 27 and 11.2 grams of ATS, respectively. Filter A contained about 2.5 times as much ATS as Filter B. In a test using
- NSF protocol 53 both filters removed >99% of lead at pH 8.5 and 6.5.
- the results of this test indicate that the process used in formulating Filter A was inefficient as compared to Filter B.
- ATS at a cost of about $0,025 cents per gram, can be the single most expensive additive used in water filtration for the removal of lead and heavy metals.
- Filter A required $0.40 US more ATS than Filter B.
- Gravity flow for liquid filtration essentially means that the only force driving a liquid through a filter is the amount of head directly over the filter.
- the weight of the liquid creates force. This weight may be increased by increasing the head or distance between the liquid's highest level and the filter. The head will gradually diminish as the reservoir of liquid flows out through the filter.
- very little head pressure on the filter can be generated in portable devices, which are the primary applications for gravity flow filtering.
- the amount of head is limited to about 70 mm over the filter.
- the solution to achieve an acceptable flow rate resides in the development of a filter which will indeed flow while still filtering out contaminants.
- an optimum formulation was found to be 25% to 35% PMX CF-1 to about 65%> to 75% activated carbon granules in the 50 to 150 micron range.
- the coarse granules combined with the PMX CF-1 material create an open pore matrix that flows easily with very minimum head of liquid over the filter.
- the actual formulation may be further modified according to the desired performance of the filter. For example, a carafe style pitcher usually has only a few inches of head over the filter and therefore must have excellent flow through characteristics with very little pressure drop.
- a coarse granular activated carbon particles in the 50 to 150 micron range is blended in a ratio of 70% carbon to 30% PMX CF-1.
- Factors that affect the flow rate will include the wall thickness of the filter and the total wetted surface area of the filter's exterior. In other gravity flow devices where there may be more head over the filter, or where the flow rate need not be fast, and where the challenge is to remove more contaminants, the filter' s pore diameter may be reduced through the introduction of the PMX CF-2 material while decreasing the median particle distribution size of the compounds or 22
- the preferred embodiment for gravity flow devices starts in a range of from about 30% or more PMX CF-1 to 70% adsorbent/compound blend. This was shown in one experiment where a molded cup shaped filter measuring 10 cm long by 5 cm in diameter was created using 30% PMX CF-1 and 70% granular activated carbon in the 50-150 micron particle distribution range.
- the process used in making a gravity flow filter may be modified where necessary to create a more open pore structure, especially where a faster flow rate is desired.
- the filter preferably a cup-shaped filter
- the cup was filled to the brim with tap water and allowed to sit. After about 60 seconds the cup began to weep droplets of filtered water along its sides. The bottom of the cup had been made with a slightly thicker wall to discourage the liquid from merely finding the path of least resistance. Over a period 10 minutes the cup gradually wetted down as it was re-filled continuously. As the cup became fully moistened the flow rate increased to well above 200 ml per minute. Later experiments discovered that a greater amount of head above the brim of the cup increased liquid flow to 500 ml per minute.
- WVDE - 21953/0001 - 207293 v2 gases The ability to permanently bond carbon particles to the polyolefin matrix enables the filter cubes or small square, rectangular or circular tabs, or the like, to be manufactured without the shedding of carbon fines while enhancing performance by over 200%. Enhanced performance is achieved because the molded part is highly porous with very little pressure drop. Air that vents the disk drive passes through the molded carbon part instead of around it.
- US Patent 6,168,651 teaches a technique of adding projections to a compressed, molded carbon part to expose more surface area to the air that is directed to flow around and not through the part, since the adsorption takes place on the surface of the part.
- the flow through capability of the carbon part may be formulated so that the incoming air will flow through rather than around the carbon part. This increases the available surface area of the carbon to the humidity and undesirable gases in the air used to ventilate the disk drive. Acid gases, for example, will corrode the head of a disk drive and cause it to fail. Too little as well as any excess humidity also can have an adverse affect on disk drives.
- a filter in the preferred embodiment is made using about 50% by weight of PMX CF-1, because of its superior bonding capability with the remainder being of compounds and adsorbents to remove common tap water contaminants such as lead and chlorine.
- the use of only PMX CF-1 material instead of a combination with PMX CF-2 further creates a filter with excellent depth filtration and minimal pressure drop. Premature clogging problems are aggravated by flow rates that are very slow, which is typical in ice maker applications.
- the filter of the present invention when used for such appliances, is superior because it will continue to filter at high performance levels without clogging and without being effected by freezing temperatures.
- An ideal formulation of materials here would be, by weight, 50% PMX CF-1, 25% powdered activated carbon with a mean particle size of about 22 microns, and 25% granulated activated carbon in the 50 to 150 micron range.
- This formula may be modified to include a lead removal material where needed. In such an instance, the activated carbon is proportionately reduced to 40% to accommodate about 10% of a lead removal material such as Engelhard' s ATSTM.
- ⁇ DE - 21953/0001 - 207293 v2 resulting filter is durable, exhibits excellent depth filtration and yet has sufficient filtering material to provide consistent performance. While the physical characteristics of the filter for refrigeration purposes have been reviewed above, an equally important improvement is the increased performance of activated carbon in low temperature filtration applications. Activated carbon's ability to adsorb chlorine is increased by higher temperature, hi one test, chlorinated tap water was passed through a filter of granulated activated carbon in the form of a block matrix. A comparison was evaluated by increasing the water temperature from 70 degrees F to 110 degrees F. Notable improvement was achieved at higher temperatures since chlorine, a gas by nature, becomes increasingly volatile as the temperature increases.
- the current invention enables a filter to be formulated to only one half the cubic dimensions of other filters while having more features and benefits.
- Another feature found to be advantageous in refrigeration is the ability for the filter to be molded into panels or shapes other than cylinders, which are a limitation of carbon blocks.
- the filter may be made into a flat panel which can fit into less usable space within the cabinet, rather than protrude into usable shelf space. Chlorinated tap water flows through the panel from one side to the other with the panel's thickness acting as the filter matrix.
- Application 4 Organic Vapor Mash Organic vapor masks protect the user from inhaling harmful chemical vapors from the air.
- the prior art involves the use of a very coarse mesh, granular activated carbon that has been impregnated with potassium hydroxide or potassium iodide to enhance the adsorption of acid gases.
- the carbon is densely compressed into a canister with perforations on one side for intake of air into the mask. As the air passes over 26
- a porous part is molded to approximate the same size of the canister in terms of outside diameter (OD).
- the part is formed like a shallow cylinder that has a continuous side wall and a closed end of the same thickness of about 6 mm with a radius so that the closed end is rounded. The air flows in a radial direction through the cylinder outside closed end and side wall to the shallow core and into the mask.
- the formulation of the part involves using, in the preferred embodiment, a granular activated carbon with a particle distribution in the 75 to 150 micron range (60% by weight) to PMX CF-1 (40% by weight).
- the part is vibrated only slightly to avoid particle migration and pore size reduction.
- the ability to replace the loose bed carbon with a more advanced organic vapor filter in the current invention draws upon the special characteristics that include molding capability of the parts, low pressure drop, and higher performance.
- granular carbon beds for this application have particle distributions in the 500 to 2000 micron range, here the particles are much finer by comparison and offer greater surface area for adsorption.
- Air and Gas Filtration The principles of causing the surface area of the filtering material to be greater while decreasing the pressure drop enhance the filtering perfo ⁇ nance of gases such as air.
- Prior art methods include the creation of flat panels where coarse particles of activated carbon are compacted into a given space; alternatively, some filters designed for air or gas bind fine carbon powders to a fibrous material. The air or gas flows across the fibers and in doing so become exposed to the filtering material, which is made of or incorporates activated carbon.
- flat panels may easily be molded into a geometrical shape that is defined by a length, a width and a thickness. The panel is self supporting and does not require any structure to contain it.
- Ease of flow through is achieved by providing coarse granules of filtering material such as granular activated carbon particles with PMX CF-1.
- Still another application in the filtration of gases is the removal of toxic organic contaminants from cigarette smoke.
- Highly activated carbon particles may be bonded to PMX CF-1 and formed into a filter disk that is installed in the tar filter. As the smoke passes through the carbon-polymer matrix any toxic organic vapors are instantly taken up and held on the surface of the carbon particles.
- Application 6 Water Filters The increased demand for high performance in water filters is related directly to the continued discovery of residual chemicals, metals and microorganisms found in drinking water and the accompanying publicity. Contaminants in water may be classified into four groups: (i) suspended solids; (ii) heavy metals; (iii) organic based 27
- Water filters may be formulated to be durable with excellent density and having available a wide range of median pore diameters. The median pore diameters may be manipulated by changes in the particle distribution of the materials being processed as well as the polymers used to create the filter matrix.
- a high flow rate filter in one embodiment may be formulated as follows: It would have 30% by weight of PMX CF-1, 20% by weight of PMX CF-2 and 50% powdered activated carbon in the range of 20 microns to 45 microns. To include the removal of heavy metals, this formula may be adjusted to include about 7% to 15% of a sorbent such as Engelhard Mineral's ATSTM zeolites. The exact formula will be determined according to the specifications.
- the formula may be adjusted by modifying the powdered activated carbon (PAC) with a blend of medium coarse carbon in the 50 micron to 150 micron particle distribution range.
- PAC powdered activated carbon
- the exact amount added depends on part geometry and other factors such as desired flow rate, pressure drop and depth filtration capability.
- Typical water filter geometry is a cylinder, usually open at both ends or open at one end only. The cylinder is about 9.5 inches long by 2.25 to 3.0 inches OD with an inner diameter (ID) of about one inch. Water flows radially from the OD to the ID and then out one of the open ends.
- a typical filter of this type will flow at 4 to 6 liters per minute and can be formulated to remove chlorine, pesticides, MTBE (a gasoline additive), VOCs, lindane, asbestos, heavy metals such as lead, and microorganisms such as Cryptosporidium.
- the exact amount is determined by the capacity and performance requirements placed on the filter. For example, very high flow filters with this geometry and dimensions may require 15%> by weight of a lead removal sorbent where performance demands > 99%> lead reduction at 6 LPM, while at 4 LPM only 10%> is needed. In some instances, to meet the minimum NSF 53 protocol only 7% may be needed.
- Another feature of the present invention is the ability to remove contaminants in water through tortuosity rather than absolute micron filtration. One such difficult contaminant is E.
- a silver impregnate or silver ion or silver/zinc ion based antimicrobial powder is first blended into the CF-1 and CF-2 polymer. There is an electrostatic attraction that creates a temporary bond between the two compounds such that the minute antimicrobial powders, often in the micron diameter range of 0.2 microns to 5.0 microns, cling to the surface of the PMX particles. In the next step the other materials are blended. During processing, the majority of the fine antimicrobial powders have been placed where they will immediately form a permanent bond to the structure of the filter.
- a typical loading onto the filter by weight may be in the range of one percent up to five percent.
- the activity of the silver which differs depending on the particular characteristics of the chosen antimicrobial, deactivates the bacterium's ability to reproduce. Within 24 to 48 hours the bacterium dies naturally. Where an ordinary bacterium may reproduce 40 times per hour in this case there is no reproduction and therefore no biofilm. Dead bacteria decompose into organic matter which is instantly adsorbed by the activated carbon powder. There is no odor or residue.
- This process of eliminating pathogenic bacteria from water is unique because it does not require a biocide agent such as iodine or chlorine nor electricity to powder a UV (ultraviolet light) lamp, which are two common methods of removing bacteria.
- Flock is a byproduct of textile manufacturing in which remnant threaded material is cut into very small lengths down to only a few microns. These short threads bond easily to the polymer during sintering and then act as a net to capture particulates. This may be combined with coarse activated carbon particles to pre-filter both particulates and organics, including chlorine, from water. In the filtration of water, the present invention should not be considered limited to the examples above, but rather should be understood to encompass various filter
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Dispersion Chemistry (AREA)
- Hydrology & Water Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Filtering Materials (AREA)
- Water Treatment By Sorption (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Treatment Of Water By Ion Exchange (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
Description
Claims
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2004/016792 WO2005118108A1 (en) | 2004-05-26 | 2004-05-26 | Gas porous polymer filter and methods of making it |
Publications (1)
Publication Number | Publication Date |
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EP1771234A1 true EP1771234A1 (en) | 2007-04-11 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP04821580A Ceased EP1771234A1 (en) | 2004-05-26 | 2004-05-26 | Gas porous polymer filter and methods of making it |
Country Status (7)
Country | Link |
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EP (1) | EP1771234A1 (en) |
JP (1) | JP4642843B2 (en) |
CN (1) | CN1960793B (en) |
AU (1) | AU2004320325A1 (en) |
BR (1) | BRPI0418864B1 (en) |
MX (1) | MXPA06013601A (en) |
WO (1) | WO2005118108A1 (en) |
Families Citing this family (18)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20060254427A1 (en) * | 2004-11-08 | 2006-11-16 | 3M Innovative Properties Company | Particle-containing fibrous web |
JP2011504807A (en) * | 2007-11-28 | 2011-02-17 | スリーエム イノベイティブ プロパティズ カンパニー | Antibacterial matrix and filtration system |
US8535406B2 (en) | 2008-12-18 | 2013-09-17 | 3M Innovative Properties Company | Filter element utilizing shaped particle-containing nonwoven web |
WO2012082388A2 (en) * | 2010-12-16 | 2012-06-21 | 3M Innovative Properties Company | Composite blocks with void spaces |
JP2014510626A (en) * | 2011-03-10 | 2014-05-01 | スリーエム イノベイティブ プロパティズ カンパニー | Filter media |
CN103517759B (en) * | 2011-05-16 | 2015-09-16 | 3M创新有限公司 | Porous composite block, filter assemblies with and preparation method thereof |
EP2714236B1 (en) * | 2011-05-26 | 2017-12-27 | Biolargo Life Technologies, Inc. | Activated carbon associated with iodide |
WO2013165992A1 (en) * | 2012-05-04 | 2013-11-07 | Ticona Llc | Gas phase air filtration |
KR102268189B1 (en) * | 2012-05-07 | 2021-06-23 | 도널드선 컴파니 인코포레이티드 | Materials, methods, and devices for siloxane contaminant removal |
JP2015202493A (en) * | 2014-04-16 | 2015-11-16 | 株式会社ハンドッククリーンテック | carbon block filter composition for air purification and carbon block filter |
JP2015208671A (en) * | 2014-04-28 | 2015-11-24 | 株式会社ハンドッククリーンテック | Method for producing carbon block filter for air purification |
JP6522970B2 (en) | 2015-02-03 | 2019-05-29 | スリーエム イノベイティブ プロパティズ カンパニー | Porous compact, gel-like compact and filter |
JP6085336B2 (en) * | 2015-06-18 | 2017-02-22 | 関西熱化学株式会社 | Activated carbon molded body, method for producing the activated carbon molded body, adsorbent using the activated carbon molded body, and occlusion material |
WO2019199639A1 (en) * | 2018-04-09 | 2019-10-17 | Arkema Inc. | Immobilized media device with a thermoplastic polymer binder system |
CN113423500A (en) * | 2018-12-05 | 2021-09-21 | 味之素株式会社 | Sintered body for adsorption, method for producing same, and adsorption apparatus |
CN114222619A (en) * | 2019-07-12 | 2022-03-22 | 乔治洛德方法研究和开发液化空气有限公司 | Method for producing a high-packing composite adsorbent bed, adsorber comprising a bed and adsorption-based gas separation using an adsorber |
CN114667180B (en) * | 2019-11-08 | 2024-05-03 | 美国分子工程股份有限公司 | Fluid handling in encapsulated porous structures |
TW202302198A (en) * | 2021-06-04 | 2023-01-16 | 日商大金工業股份有限公司 | Air filter medium, pleated filter medium, air filter unit, mask filtering medium, and method of recycling air filter medium |
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Publication number | Priority date | Publication date | Assignee | Title |
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WO2000018810A2 (en) * | 1998-09-25 | 2000-04-06 | Ticona Gmbh | Activated carbon filter |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
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US4753728A (en) * | 1986-04-07 | 1988-06-28 | Amway Corporation | Water filter |
DE3624414A1 (en) * | 1986-07-18 | 1988-01-28 | Michael Busch | WATER FILTER |
DE59302132D1 (en) * | 1992-01-29 | 1996-05-15 | Domme Isfried | Method for producing a filter unit and filter unit produced according to the method |
DE4211529A1 (en) * | 1992-04-06 | 1993-10-07 | Herding Entstaubung | Filter element with a dimensionally stable, permeable-porous plastic molded body |
JPH07204429A (en) * | 1993-12-21 | 1995-08-08 | Porex Technol Corp | Combined product of filter and ion-exchanging material and method for treating fluid using said combined product |
JPH0827303A (en) * | 1994-07-19 | 1996-01-30 | Idemitsu Kosan Co Ltd | Porous material and production thereof |
FR2759087B1 (en) * | 1997-02-06 | 1999-07-30 | Electricite De France | POROUS COMPOSITE PRODUCT WITH HIGH SPECIFIC SURFACE, PREPARATION METHOD AND ELECTRODE FOR ELECTROCHEMICAL ASSEMBLY FORMED FROM POROUS COMPOSITE FILM |
JP3484121B2 (en) * | 1999-12-28 | 2004-01-06 | 三ツ星ベルト株式会社 | Method for producing filter molded body |
JP5064618B2 (en) * | 2001-05-31 | 2012-10-31 | 三ツ星ベルト株式会社 | Water treatment filter |
CN1351822A (en) * | 2001-11-02 | 2002-06-05 | 崔树萍 | Penetration filter material and preparing method and use of said material |
-
2004
- 2004-05-26 JP JP2007515013A patent/JP4642843B2/en not_active Expired - Fee Related
- 2004-05-26 AU AU2004320325A patent/AU2004320325A1/en not_active Abandoned
- 2004-05-26 BR BRPI0418864A patent/BRPI0418864B1/en not_active IP Right Cessation
- 2004-05-26 WO PCT/US2004/016792 patent/WO2005118108A1/en active Application Filing
- 2004-05-26 CN CN2004800431558A patent/CN1960793B/en not_active Expired - Fee Related
- 2004-05-26 EP EP04821580A patent/EP1771234A1/en not_active Ceased
- 2004-05-26 MX MXPA06013601A patent/MXPA06013601A/en not_active Application Discontinuation
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2000018810A2 (en) * | 1998-09-25 | 2000-04-06 | Ticona Gmbh | Activated carbon filter |
Non-Patent Citations (1)
Title |
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See also references of WO2005118108A1 * |
Also Published As
Publication number | Publication date |
---|---|
JP4642843B2 (en) | 2011-03-02 |
JP2008500165A (en) | 2008-01-10 |
AU2004320325A1 (en) | 2005-12-15 |
CN1960793B (en) | 2011-10-05 |
BRPI0418864B1 (en) | 2018-11-21 |
BRPI0418864A (en) | 2007-11-20 |
WO2005118108A1 (en) | 2005-12-15 |
MXPA06013601A (en) | 2007-03-15 |
CN1960793A (en) | 2007-05-09 |
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