MXPA05011629A - Advanced filtration devices and methods - Google Patents

Abstract

A filter media comprises a medium for capturing and neutralizing harmful substances. Methods for fabricating a low-pressure, high efficiency filter media for capturing harmful substances produce filter media having engineered pores that have an engineered pour size dispersion, which may be monodispersed and uniformly arranged. Neutralizing components may be coated on filter media, providing both increased capture efficiency and neutralization of at least one harmful substance, such as harmful pathogens, aerosols, particulates, VOCs, gases and vapors.

Description

DEVICES AND METHODS FOR ADVANCED FILTRATION FIELD OF THE INVENTION The field of the invention is the filtration, in particular the filtration with the neutralization or recovery of particles, aerosols, vapors and noxious gases.

BACKGROUND OF THE INVENTION Noxious substances are present in the air, such as, for example, toxins and pathogens, which can cause diseases at excess concentrations. There are many sources of these harmful substances, which can be transported over long distances or can be confined to an indoor environment. Indoor air pollution is a serious concern. For example, toxic mold has become a concern for homeowners and businesses. In addition, recent events make possible the use of pathogens and toxins, as a terrorist weapon, a serious concern. It should be understood that the term "noxious substances" includes natural substances, such as, for example, dust, mold toxins and pollen dusts, synthetic substances, such as, for example, smoke and volatile organic compounds, and terrorist weapons, such as, for example, VX, sarin, ricin and anthrax. The chemical formulas for four harmful substances are shown in Figures 1A-1D. Some toxic chemicals are fairly reactive polar compounds. For example, four categories of known chemical weapons include asphyxiating agents, agents for producing blisters, blood agents and nerve agents. Asphyxiating agents, such as chlorine and phosgene, attack the lungs. Blister agents, such as, for example, mustard gas (HD), are volatile liquids that cause blistering in organic tissue when absorbed on the skin, in the eyes, or inside the lungs. Blood agents, such as, for example, hydrogen cyanide (HCN), are absorbed through the lungs in the blood, or via the intestines in the case of HCN carried by water, where irreversibly binds to hemoglobin and prevents the absorption of oxygen. Nerve agents, such as, for example, sarin (GB), soman (GD), and VX, are extremely potent and deadly when inhaled or adsorbed through the skin or lungs Chlorine, phosgene, and hydrogen cyanide are gases. GB, GD, VX, and HD are semi-volatile liquids that are commonly dispersed as an aerosol or combination of gas and aerosol.

The decontamination of surfaces after exposure to toxic substances has been studied. The predominant decontamination strategies are adsorption (followed by incineration) and neutralization by chemical reaction. While the structures and functions of these toxic chemicals vary widely (Figures 1A-1D), they are all quite reactive materials, which can be quickly neutralized by the correct combination of reagents. For example, toxic chemicals can react rapidly with oxidizing agents, alkaline solutions, or both. Nerve agents undergo rapid oxidation with phosphoric acid in the presence of strong oxidants. HD also undergoes oxidation, although great care must be taken to avoid partial oxidation to the substantially less toxic but still dangerous sulfone derivative. Hydrogen cyanide, chlorine, phosgene, HD, Sarin, Soman, and VX are all rapidly attacked by alkaline solutions to provide relatively benign products. Volatile organic compounds (VOCs) are prevalent in all residential and commercial buildings and have been found to cause serious health consequences for occupants. While national and international health-related agencies have varying classifications, VOCs are widely recognized as compounds that are gaseous or have a significant vapor pressure at room temperature. For example, products such as, for example, chipboard, plywood, fabrics, coatings and insulation release significant amounts of gaseous formaldehyde, a common VOC. The maximum formaldehyde concentrations in homes and workplaces typically vary from 0.04-0.4 ppm. Regular exposure to maximum concentrations greater than 0.06 ppm can result in serious health consequences including irritation, mucous, rash, severe allergic reactions, fatigue, headache, nausea, depression, and a significantly increased risk. of throat cancer with chronic, long-term exposure. Other VOCs commonly released from products in the home are benzene, toluene, styrene, acetone, para-dichlorobenzene, chloroform, tetrachlorethylene, acrylic acid esters, and aliphatic ketones and alcohol. In addition, building occupants are often exposed to low levels of other toxic gases, including volatile sulfur complexes, and ammonia gas. Most VOCs can be neutralized by oxidizing agents, alkaline solutions or both. Systems for air filtration or climate systems in buildings, vehicles and personal protection equipment are intended to improve the safety and / or quality of the air we breathe. However, these filtration systems, such as those used in heating, ventilation and air conditioning (HVAC) systems, are not capable of preventing the dispersion of harmful concentrations of microbes, particles, vapors throughout a structure. and gases. See Table I for a comparison of the size of some common harmful substances. Systems for air filtration in vehicles are not capable of reducing the exhaust emissions of normal vehicles to safe levels, much less any unexpected release of harmful substances in the vicinity of a vehicle. Even personal protection equipment that is designed to avoid exposure to harmful substances has severe limitations with respect to the duration of exposure allowed before a replacement of filter elements is required to ensure continued protection. In one example, formaldehyde concentrations can exceed levels that can cause harm to human health simply from natural and synthetic sources. A few HVAC systems can neutralize this substance. In fact, HVAC systems are more likely to disperse toxins released in-house in a building instead of providing some protection to the occupants. High Efficiency Air Particle (HEPA) filters can be effective in trapping pathogens and airborne particles. If used, these filters could offer some limited, passive defense against some harmful substances, such as, for example, anthrax. HEPA filters are ineffective against many other harmful substances, including most volatile organic compounds (VOCs) and other harmful substances in the form of vapor, aerosol or gas. Also, HEPA filters are quite efficient for capturing particles, although HEPA filters offer a concomitant high operating cost, which is related to the high resistance to air flow through the HEPA filter. Resistance to air flow, which can be measured as a pressure drop, requires that more energy be used to circulate air through the filters, which increases operating costs. In addition, the pressure drop across the HEPA filters creates a high retro-pressure, which can lead to leaks in the HVAC ducts, dramatically decreasing the overall capture efficiency of the system.

Granular activated carbon filters, such as those used in conventional gas masks, are known to provide short-term protection from harmful gases. Activated carbon filters suffer from serious limitations which has prevented their widespread adoption in HVAC applications and this reduces their effectiveness in applications for personal protection, such as filters in protective masks. Specifically, the mechanism of adsorption of gases in activated carbon is reversible. In this way, the absorbed gas can be released by changes in temperature, humidity or the chemical composition of the air. For example, the presence of a second gas with a higher affinity for the granular activated carbon can cause the release of a previously absorbed gas. Additionally, the activated carbon, which is not polar, shows an adsorption of relatively efficient polar gases. These limitations mean that a comparatively high density of activated carbon is necessary to provide a reasonable filter life time. As discussed in relation to HEPA filters, this high density results in a large pressure drop across the filter, which is not convenient in a filtration system. Finally, granular activated carbon, which remains loose in a filter bed, is susceptible to the formation of open channels, which significantly reduces the efficiency of the filter. U.S. Patent No. 6,435,184 which is incorporated herein by reference, for example, discloses the structure of a conventional protective mask. U.S. Patent No. 3,017,329 was issued in 1962 and discloses a germicidal and fungicidal filter using a conventional non-woven filter medium. The filter media is coated by a conventional process, such as, for example, by spraying or bathing the filter medium using an active ingredient. The active ingredient was selected from organo-silver compounds or organotin compounds, which have a neutral pH, although they are quite toxic to mammals. The treated filter was then heated to extract water, which was used as a solvent in the coating process and to cure a binder that binds the active ingredient to the filter medium. U.S. Patent No. 3,116,969 discloses a filter having an antiseptic quaternary ammonium chloride compound with alkyl aryl, which is maintained to conventional filter fibers by a sticky composition that includes a hygroscopic agent, a thickening agent and a film-forming agent. U.S. Patent No. 3,820,308 discloses a sterilizing filter having a moist oleaginous coating containing a quaternary ammonium salt as the sterilizing agent. M. Dever et al. Tappi Journal 1997, 80 (3), 157 present the results of a study of the antimicrobial efficacy of an antimicrobial agent incorporated inside the fibers of a meltblown polypropylene filter medium. Each of the three different, unidentified agents were mixed with polypropylene, which was then blown conventionally to form a filter medium. Only two of the agents could be detected by FTIR after processing, and these two agents provided antimicrobial properties. However, the agents adversely affected the physical properties of the polypropylene, causing thickening of the fibers of the filter medium and reducing the collection efficiencies of the polypropylene without mixing. K. K. Foard and J. T. Hanley, ASHRAE Trans. , 2001, v. 107, p. 156 present the results of field tests using filters treated with one of three unidentified antimicrobial agents. The known antimicrobial filter treatments produced little effect under the test conditions, showing growth in the same way in both untreated and treated counterparts. A. Kanazawa et al., J. Applied Polymer Sci. , 1994, v. 54, p. 1305 disclose an antimicrobial filter medium using covalently immobilized antimicrobial phosphonium chloride entities on a cellulose substrate. Phosphonium salts with long alkyl chains tend to have a greater ability to capture bacteria. M. Okamoto, Preceedings of the Institute of Environmental Sciences and Technology, 1998, p. 122 discloses the use of silver zeolite as an antimicrobial agent in a climate filter. The silver zeolite is attached by an adhesive to one side of the filter. U.S. Patent Publication No. 2001/0045398 discloses a process for the preparation of a nonwoven porous material having particles immobilized in the interstices thereof. The particles are added by contacting the material with a particle suspension and forcing the suspension through the material, capturing the particles that entered the interstices of the porous material and providing an antimicrobial barrier. The English language extract of the Publication International. No. WO 00/64264 discloses an organic polymeric bactericidal filter material that is made from a polymeric base comprising a structure and a polymeric pendant group attached to the structure. The material comprises units derived from an N-alkyl-N-vinylalkylamide and tri-iodide ions attached to the polymeric material. International Publication No. WO 02/058812 discloses a filter medium containing time-release micro-capsules of the antimicrobial agent. The microcapsules contain the agent suspended in a viscous solvent, which slowly diffuses the porous layer of the microcapsule. The microcapsule can be maintained in the conventional filter medium using gum arabic as an adhesive. Other methods for removing airborne pathogens include percolating air through a liquid, electrostatic precipitation (e.g., U.S. Patent No. 5,993,738), ultraviolet light (e.g., U.S. Pat.

No. 5,523,075), although each of these uses significantly higher energy which makes them unacceptable for high volume HVAC applications. All the above examples have deficiencies that prevent their widespread adoption in systems for air filtration, such as, for example, the provocation of problems to dispose of harmful waste, which have high operating costs and which have high costs for the production and maintenance of the filtration systems. In this way, there is an urgent need for a substantial improvement in the protective capacities of low cost and effective filters. Particularly it is necessary the consumption of low energy in the capture and neutralization of particles, pathogens, aerosols, vapors and harmful gases. The generation of sub-micrometric patterns can be achieved using photolithographic processes, as is known in the art of manufacturing semiconductor devices, such as, for example, the process disclosed in United States Patent No. 5,110,697 which is incorporated in the present as a reference. The generation of 1-50 micrometric patterns is easily achieved by well-known conventional processes using photolithography and other conventional techniques, such as, for example, color printing and engraved sheet printing. In color printing, the processes for recording the precise placement of multiple layers are well known. Also, the formation of etched sheets is known to provide durable patterned roller surfaces for processing viscous molten fluids or softened solids. For example, to form the engraved sheets, a molten polymer is compressed through a narrow opening, known as the point of contact region of a set of calendering rolls with embedded surface characteristics. These processes, which are not related to the manufacture of conventional filter media, are referred to herein as conventional printing of substrates.

SUMMARY OF THE INVENTION A filter comprises a means for capturing and neutralizing harmful substances. A high efficiency, low pressure pre-filter can be used to capture particles before they enter a filter medium. The advanced filter media comprises a filtration component and a neutralization component. The neutralization component is a film of viscous organic components and reactive compounds coated in a thin film of a substrate, providing a recovery with low pressure drop, high performance for harmful substances. In one embodiment, a neutralization component is supported by a filtering component, such as, for example, fibers, which support the neutralization component. The fibers are distributed in the filter in such a way that the air passing through the filter must pass through sinuous channels through the fibers. In this way, the harmful substances that entered the air come into contact with the neutralization component, which neutralizes one or more of the harmful substances.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1A-1D show the chemical formula for various toxic substances. Figure 2 illustrates an embodiment of the invention having fibers coated by a recovery layer. Figure 3 shows a modality of a broad spectrum filter for the recovery of a plurality of toxic or noxious substances. Figure 4 shows filter fibers without a recovery layer. Figure 5 illustrates fibers coated with a recovery layer that is spread with a solution containing mold spores after being placed in an incubator at a temperature and humidity suitable for mold growth. Figure 6 illustrates the fibers of Figure 4 that are coated and incubated in a similar manner, as in Figure 5, which shows substantial mold growth as compared to the embodiment illustrated in Figure 5. Figure 7 shows the fibers of a filter according to the prior art. Figure 8 illustrates a filter comprising a coarse pre-filter, a neutralizing component that coats the coarse pre-filter, and a media with a foil filter. Figure 9 illustrates the concept of fiber packaging, which means placing a layer or layers of functional polymer on the surface of a fiber, providing a recovery layer. Figure 10 illustrates one embodiment of a sheet filter media. FIGS. 11 to 11C show a method for preparing a sheet filter media.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES In one embodiment, a filter comprises a filtering component and a neutralization component. The filtering component can be made up of several different layers of a filter medium or can be continuous. In spite of this, the neutralization component can be an individual active agent, a combination of active agents or it can be a plurality of active agents striated in separate areas in the filtration component. For example, the neutralization component is supported by the filtration component, as shown in Figure 2, which acts as a substrate for the neutralization component. Conventional filtration media use randomly entangled and / or entangled fibers, as shown in Figure 7, which cause the air passing through the filter to pass through sinuous air passages between the fibers. The fibers are distributed in the filter in such a way that the air passing through the filter must pass through sinuous channels around the fibers. In this way, the harmful substances that entered the air are brought into contact with the neutralization component, which neutralizes one or more of the harmful substances. In one example, a filter for neutralization of harmful substances comprises a conventional non-reactive filter medium, such as, for example, polymeric fibers, coated with a recovery layer. The recovery layer comprises a host material that houses one or more of the neutralizing substances, such as, for example, basic acidic substances or oxidants. The host material can have a sticky surface which causes the particles that enter and impact on the sticky surface to adhere, improving the efficiency of particle capture, and allowing additional time for neutralization of the particles, such as, for example, pathogens. It was found that fibrous coating filters with thin layers of viscous organic components in a recovery layer adsorb organic gases and aerosols. The high-performance filter media is equipped with relative coatings adapted to efficiently capture and neutralize toxic and harmful substances, such as, for example, pathogens, VOCs and other chemicals. The reactive coatings comprise reactive components for neutralizing toxic or noxious substances and a coating matrix which improves the adhesion between the reactive component and the filter media. Examples of reactive components are oxidizing agents, such as, for example, sodium hypochlorite, calcium hypochlorite, and potassium permanganate; acidic complexes, such as, for example, acrylic acid derivatives and sulfonic acid derivatives; and basic complexes such as, for example, sodium alkoxides, tertiary amines and pyridines and compatible mixtures thereof. The matrix component is typically a polymeric material such as, for example, poly (vinylpyrrolidone), poly (vinylpyridine), poly (acrylic acid) (free acid or salt), poly (styrenesulfonic acid) (free acid or salt), poly (ethylene glycol) ), polyvinyl alcohol, polysiloxanes, polyacrylate derivatives, carboxymethylcellulose, and mixtures and copolymers thereof. In some cases, such as for example, poly (styrenesulfonic acid) the matrix component can also act as the reactive component. The matrix component may also consist of low molecular weight, non-volatile complexes, such as, for example, glycerol and ethylene glycol oligomers, to stimulate affinity with the toxic or white noxious substance. The polymer component can also be degraded to prevent the removal of the reactive coating of the filter fiber under extreme conditions. The reactive coating technology can be applied to any fibrous filter media including synthetic glass and polymer fibers such as, for example, polyester and cellulose derivatives. One advantage of these fairly efficient filters is the high probability of recovery of the toxic or harmful substance or substances. This is a function of the structure of the filter, which preferably causes a greater number of collisions between the toxic or noxious substances and the filter medium, and the probability that each collision with the filter medium results in absorption or neutralization. No individual set of conditions can be applied universally to all substances. In this way, for multi-phase filtering, it may be convenient, as shown in Figure 3, for a wide-spectrum filter, for multiple environments, for example. As reported, each of the following examples of the neutralization components provides protection against specific harmful substances; however, other harmful substances that have not been tested can also be neutralized.

EXAMPLE 1 Formation of an Oxidizing Glim Coat An aqueous solution of the following was prepared: 20% by weight tetraethoxysilane, 20% by weight bis (triethoxysilyl) methane; glycerol at 10% by weight, and citric acid at 0.05% by weight. In the above solution a fiberglass pad was immersed, dried, and then cured by steam heating for 6 hours. The pad was then immersed in an aqueous solution of 20% sodium hypochlorite and 0.5% cyanuric acid and then dried. The resulting filter was effective for the neutralization of diethyl sulfide.

Example 2 Formation of an oxidizing coating An aqueous solution of the poly (vinylpyrrolidone) at 10% by weight was prepared. In the above solution, a fiberglass pad was immersed, dried, and then irradiated under a UV lamp for 6 hours to degrade the polymer. The pad was then immersed in a 2% by weight aqueous solution of calcium hypochlorite and air dried. The resulting filter was effective for the neutralization of formaldehyde.

Example 3 Formation of an oxidizing coating An aqueous solution of poly (vinylpyrrolidone) at 10% by weight and potassium permanganate at 2% by weight was prepared. In the above solution, a fiberglass pad was immersed and then air dried. The resulting filter was effective for the neutralization of formaldehyde.

Example 4 Formation of an oxidizing coating An aqueous solution of poly (vinylpyrrolidone) at 10% by weight was prepared. In the above solution, a fiberglass pad was immersed, dried, and then irradiated under a UV lamp for 6 hours to degrade the polymer. The pad was then immersed in an aqueous solution of 2% potassium permanganate and air dried. The resulting filter was effective for the neutralization of formaldehyde.

Example 5 Formation of an oxidizing coating An aqueous solution of poly (ethylene glycol) at 10% by weight and 2% by weight calcium hypochlorite was prepared. In the above solution, a fiberglass pad was immersed and dried with air. The resulting filter was effective for the neutralization of formaldehyde.

Example 6 Formation of an oxidizing coating An aqueous solution of sodium salt of 10% by weight poly (acrylic acid) and 2% by weight calcium hypochlorite was prepared. In the above solution, a fiberglass pad was immersed and dried with air. The resulting filter was effective for the neutralization of formaldehyde.

Example 7 Formation of an alkaline coating An aqueous solution containing 30 wt.% Glycerol, 5 wt.% Polyethylenimine and 0.25 wt.% Glycerol triglycidyl ether propoxylate. A fiberglass pad was immersed in the solution, dried and cured at 100 ° C for 6 hours. The glass fiber pad was then immersed in a solution of aqueous sodium hydroxide with pH 12 or higher which contained 30% by weight glycerol, was removed from the solution, and dried at 50 ° C for two hours. The resulting filter was effective for the neutralization of hydrogen cyanide gas.

Example 8 Formation of an acid coating An aqueous solution of the following was prepared: 30% by weight glycerol; 5% by weight styrenesulfonic acid divinylbenzene 0.1% by weight, 2,2'-azobisisobutyronitrile 0.13% by weight, potassium persulfate 0.02% by weight and sodium dodecylsulphate 0.5% by weight, in the previous solution was immersed a fiberglass pad, dried, and then cured at 85 ° C for 2 hours. The resulting filter was useful for the neutralization of ammonia gas.

Method for the rapid production of a sheet filter media Figure 10 illustrates a partial approach of a sheet filter media having a uniform rectangular mesh of monodisperse pores. Monodisperse means that the pore size is substantially the same in at least a substantial portion of the sheet filter media. More generally, the method can produce filter media having any desired pore distribution. For example, Figure 8 shows another filter medium having a honeycomb structure; however, any structure can be formed by the method for the rapid production of sheet filter media. A method for producing a filter having a designed pore distribution provides for the rapid production of the sheet filter media by direct molding and printing. A conventional printing method for substrates is used to form a two-dimensional or three-dimensional porous sheet filter media. By "direct molding and printing" it is to be understood that the fibers of a two-dimensional or three-dimensional filter medium are in situ from precursors during the generation of the structure of the desired filter medium by a printing method. The process is distinguished from conventional papermaking and papermaking, for example, by forming subsurface and larger porous structures formed by the generation of fibrous patterns in situ. The structure of the resulting filter medium is a pattern of organized and interconnected fibers. The pattern of interconnected fibers can be formed in a filter media that exhibits both strength and flexibility not available from conventional filter media. It is believed, without limitation in any way, that the surface tension forces are responsible for causing a spontaneous segregation of a biphasic solution or emulsion of the polymer precursors and a solvent, for example, on a substrate with ridges having a surface tension and slits that have another surface tension. In this way, the pattern of the fibrous filter medium can be disposed by this separation on a printing substrate that is pattern patterned using a conventional printing method for substrates, such as for example, photolithography, a process similar to color printing. or a recorded sheet print. For example, an aqueous precursor emulsion is prepared for use with a photolithographically prepared printing substrate having a pattern of ridges and grooves on its surface. The emulsion is prepared in such a way that at least one precursor phase surrounds the edges and fills the slits with water. Alternatively, the opposite orientation of the precursor phase and the aqueous phase, or other solvent, containing the precursor phase can be selected by controlling the water-in-oil or oil-in-water nature of the multi-phase emulsion or solution. The precursor phase may contain substances that form fibers by catalytic growth by polymerization, solidification, crystallization, steam or any other consolidation process that maintains the orientation provided by the pattern of the ridges and slits from the surface of the printing substrate . For example, the precursor phase comprises polymeric precursors that form polymer fibers in situ during phase separation on the ridges of the substrate surface. Then, the removal of the aqueous phase or solvent can be achieved by evaporation, for example, leaving well-defined spaces of a particular size, configuration and distribution between the polymer strands that interconnect in the pattern of the ridges. A network of interconnected fibers is formed that define pores in the filter media. The fibers can be coated by the neutralizing component to assist in the capture and neutralization of a harmful substance. In one example, the fibers are substantially coated by the neutralizing component, which provides both efficient capture of particles and adequate neutralization of noxious gases, such as, for example, volatile organic compounds (VOCs). In another example, the precursor phase is dissolved on digested cellulosics to a proteinaceous polymer in an aqueous solution, and the aqueous solution is mixed with a solvent in an emulsion, which segregates towards the ridges on the surface of a printing substrate. In this example, the precursor phase is formed in situ in the slits. The resulting fibers maintain the pattern of the slits, which can be any pattern. For example, the pattern forms a mesh, a honeycomb or any other two-dimensional geometric configuration. In one embodiment, the separation of the precursor phase from the aqueous or solvent phase is not attributed to different materials in the ridges and grooves on the surface of the printing substrate. Instead, the separation is caused by temperature differences between the material at the flanges and within the slits, which leads to a spontaneous assembly of a precursor phase. In this specific example, the fed precursor does not need to be even a multi-phase system. For example, prepolymers or polymers can be selected to form comparatively cool characteristics of a metastable solution, leaving a rich solvent and a stable solution at the comparatively hottest spots. In this way, a sheet filter medium can be formed from a non-aqueous polymer solution. In another alternative, the surface of the printing substrate has no ridge or slits. Instead, the surface is practically flat, and consists of a pattern of different materials, such as, for example, a pattern printed on the surface of a printing substrate. Different materials have surface tension forces that differ with the emulsion or solution, which causes the separation of the precursor phase and the aqueous phase or solvent. In this way, a fiber pattern can be formed from the printing substrate, as in the above. In yet another example, the precursor phase comprises a polyester dissolved in a monomeric / degrading / photo-initiating acrylated formulation, such as, for example, a polyethylene terephthalate classified by a mixture of benzylacrylate and bisphenol-A-diacrylate. A roller surface is patterned by a conventional substrate printing method, and the roller is used to spontaneously initiate phase migration and self-assembly according to the pattern on the roll surface. A patterned sheet is formed which is then exposed to a strong UV light source, whereby the acrylate formulation is polymerized to form an interpenetrating molecular network within the polyester fibers. The residual water or other solvent, if present, evaporates, leaving organic fibers in a filter medium of leaves that is quite reticulated and flexible. The polyester fibers are firmly fixed by the interpenetrating acrylic net, which ensures that the porous pattern formed by the roller is stable and permanent. In this way, the sheet filter medium has a pore pattern with a constant size, distribution and separation based only on the pattern provided on the roller surface and the thickness of the strands of organic polymers. The pattern on the roller can have any pattern of sub-micron size at 50 microns for filtration applications. The thickness of the strands can be controlled by the amount of the precursor component and the concentration of the precursor component in the diluent or solvent. In another example, a partially polymerized fluorocarbon suspension is subjected to contact with the surface of a roller having an etched pattern of poly (tetrafluoroethylene). The fluorocarbon material accumulates around the poly (tetrafluoroethylene) standards, leaving water (or an aqueous solution) in the metal oxide regions of the roller surface. The standard fluorocarbon is polymerized by a polymerization reaction, such as, for example, by applying heat or light, for example, UV light. Through this process, a filtering medium of very fine, filigree fluorocarbon is formed. Alternatively, polyester or nylon sheets are formed by the same process with the exception of partially polymerized precursors (or other precursors)., such as, for example, combinations of inert polymers and unreacted or partially reacted precursors) are used to form polyester or nylon. Polyester and nylon sheets also form filtering media. After a filigree architecture is formed and the polymerization is completed while mechanically lengthening the sheet filter medium in both orthogonal directions simultaneously. The elongation extracts the fibers, uniformly decreasing the diameter of the fiber and increasing the pore size. This technique, which can also be applied to other precursors, allows the production of filter media having sub-icronic fiber diameters, improving the capture efficiency against the pressure drop characteristics compared to larger fiber diameters. In another alternative embodiment, the hybrid processes use pre-spun fibers together with direct molding and printing to form the filter media. For example, the pre-spun parallel fibers can be fed into a calender having lines engraved perpendicular to the direction of travel of the parallel fibers. A feeder containing the precursor is brought into contact with the etched surface, forming patterns of the precursor material on the parallel fibers. The precursor is reacted, forming the sheet filter media in combination with the pre-spun fibers. In one example, there are large gaps between the "twisted yarns" and the "transverse yarns", that is, the fibers formed in situ and the pre-woven fibers. The new fibers adhere to the pre-spun fibers, imparting resistance to the hybrid filter medium. In addition, the focused overlap points allow the fibers to rotate, providing the material with sufficient flexibility. As before, the new fibers may be porous or solid, synthetic or natural and of simple construction or a composite structure. The new fibers may possess a core sheath geometry by using organic-aqueous systems having at least two phases wherein both phases contain polymers or precursors. Also, the pattern of the fibers can include wavy, curved or articulated lines, deposited on the pre-spun fibers, which does not make it possible to use conventional pre-spun fibers in the absence of molding and printing. In yet another embodiment, an aqueous-organic-aqueous complex emulsion can be used to design porous strands. These porous strands surround the voids, but also have gaps within the strands that form during the evaporation of water formed within the strands by chemical affinity with water or surface tension force, for example. In one example, hydrophilic and hydrophobic entities are used to produce these polymer strands, prosas. The patterns can be generated using the process of this invention which are difficult or impossible to reproduce otherwise in a filtering medium that can be produced in bulk, at low cost. For example, a sheet filter medium having at least one area with a monodisperse pore size is produced. More preferably, the monodisperse pore size, configuration and distribution is uniform across a large surface area of the filter media. The uniformity of the pore size is able to greatly increase the efficiency of the capture of particles of the filter medium per fiber volume compared to the conventional, heterogeneous filter medium. Thus, compared to conventional filter media, the sheet filter means of the present invention will have a lower pressure drop for any desired particle capture efficiency or greater particle capture efficiency for any desired pressure drop. .

In alternative embodiments, many combinations of polymers possessing hydrophilic and hydrophobic characteristics can be used to form sheet filter media in biphasic or multi-phase systems. The polymer combinations can be mixtures of amorphous or crystalline polymers, homopolymers or copolymers, inert polymers blended with reactive components (eg, monomers, oligomers, degraders and others), and viscous reactive oligomers or macromers. For example, reactions for the formation of fiber networks may be of a free radical nature or condensation. Also, the polymer or polymer precursors can be synthetic or natural. The synthetic polymers include not only hydrocarbons, such as, for example, polyolefins, polyesters, acetates, acrylics and nylon, but also fluorocarbons and silicones. When mechanical means are used for the formation of porous, tinfoil filter media, the interfacial properties between the polymer / precursor systems and the roller can be exploited to make fleece-like structures. If there is a strong but transient adhesion between the fed material and the form-producing substrate surface, then fine chains or filaments can be pulled out of the filter sheet until the viscoelasticity of the material breaks the thinnest ties between the surface of the substrate and the material fed. The numerous chains or filaments produced in this way can be similar to fleece. In one example, the subsequent healing produces blockages in this three-dimensional architecture, similar to fleece. Also, a fairly textured sheet filter media is produced by stimulating chain formation via a deliberately abraded (i.e. eroded) substrate surface that has a plurality of nanoscopic or microscopic defects. Alternatively, a fairly regular and clean sheet filter media is ensured by producing a surface free of defects and using a release agent to reduce the surface tension between the surface of the substrate and the fed material. In another example, two matching rollers have parallel grooves with one set running across the width of the first roller and a second set encompassing the circumference of the second roller. When a feed containing the precursor component is compressed through the region of contact point, a cross-fibrous pattern is produced. In one example, the lines are not continuous across the width of the first roller or along the circumference of the second roller. In this way, a pattern is created that has increased flexibility. In addition, serrated spots in the slots can be provided to the roller surfaces which results in a sheet filtering medium having raised points, which provides improved tactile properties. In another embodiment, a sacrificial layer or carrier film is used, such as, for example, a soluble film. The standards can be deposited by any of the methods of the invention on one or both sides of the sacrificial layer or carrier film. For example, these patterns can be multi-layered, and connections can be formed between the patterns on opposite sides of a sacrificial layer in the form of "holes" that are formed through the sacrificial layer, such as, for example, in forming pre-existing holes in it. After the sheet filter means are formed, the sacrificial layer can be dissolved, providing interconnections between the sheet filter media only at the specific interconnection points corresponding to the location of the holes. In this way, a complex three-dimensional geometry can be formed, which does not make it possible to use conventional filter media. Alternatively, a carrier film can simply be detached from the filter media and can be reused, perhaps, reducing the manufacturing cost. In another embodiment, a simi-solid film containing at least one precursor is compressed through a set of engraving rolls having patterned patterns on the surface of each roll. For example, patterns, such as, for example, lines and voids, are drilled through the semi-solid film, creating openings that can be improved by careful elongation of the semi-solid film. Then, the precursors of the semi-solid film are processed, such as, for example, by polymerization, curing, crystallization or solidification, to provide a completely solid sheet filtering media, which stops the openings. For example, the semi-solid film can be heated or exposed to UV light, X-rays, microwaves, electron beam or gamma radiation, so that the semi-solid film reacts completely and forms a solid sheet filter medium. The term "semi-solid film" refers to a film that exhibits the properties of a film that is not exposed to shear stress, but that is elastic under high shear stress. In this way, the semi-solid films can be handled as a solid film, but can be easily perforated by a raised surface or a roller or rollers. In one example, a semisolid film has an elastic modulus of 106 dynes / cm2 at 107 dynes / cm2. In another example, the rollers are capable of applying greater force, and the upper variation of the elastic modulus is increased to not be greater than 1010 dynes / cm2. For example, the elastic modulus of the semisolid film can be modified by mixing high molecular weight polymers with low molecular weight polymers and optional diluents, plasticized polymers and polymers with partial volume increase (by solvents). One or more of these constituents can be reactive with each other, such as, for example, inert polymers having pendant functional groups that can be degraded by a constituent or degrading agent. Also, the diluents and / or plasticizers can be polymerized or degraded either completely or partially to form interpenetrating polymer networks (IPN). The semi-solid film may also comprise reactive oligomers or macromers or mixtures thereof and other additives, such as, for example, antioxidants, ingni-retardants, mold release agents, flow aids, bioactive agents, activated charcoal, microfibrils and / or natural fibers. and / or pre-existing synthetics. In an alternative embodiment, the semi-solid film does not need to be mechanically perforated through rollers. Instead of this, opaque regions may be deposited on one or both surfaces of the semi-solid film before processing the film precursors to induce the film to solidify, such as, for example, by exposure to UV light. Then, the opaque regions, which did not solidify, can preferably be dissolved to open holes in the sheet filter medium. Masks can be used to provide opaque regions, as in standard photolithography. A mask can be prepared by coating a mylar film with a patterned metal. The patterned mylar film then imparts a shadow over the semisolid film during exposure of the semisolid film to the radiation source. For example, the radiation source can solidify the unmasked portion of the semi-solid film while it traverses on a conveyor. Alternatively, rapid laser scanning is another alternative to creating a pattern in the semi-solid film. In alternative embodiments, the semi-solid film can be independently developed, or the semi-solid films can be one or more layers in a multi-layer filter media. For example, a multilayer film can be exposed on the opposite sides simultaneously or sequentially. If one of the layers is a semisolid film, then the other layers can be deposited on it, or for any substrate. For example, a central semi-solid film may be coated with liquid precursors on either or both sides to produce an open, laminated filter structure, in fewer steps than it might require to form each independently. In one embodiment, the pore size increases in size from one side of a multilayer film to the other. In this way, a layer on a first surface of the multilayer filter has the largest pore size, while the layer on the opposite surface has the smaller pore size. The intermediate layers pass from the largest pore size to the smallest in sequence from the first surface to the opposite surface, which can be used as a progressive micro-sieve that first filters the larger particles. These multi-layer filters may have the pores substantially aligned or may have the pores biased, from one layer to the next, to increase the sinuosity of the flow air path. A sinuous path can increase the efficiency of particle capture, although the pressure drop across the filter also increases. This is within the ordinary skill in the art to determine the arrangement that is optimal for a particular application. In yet another method, ink jet printing is used to deposit a pattern of fiber precursors on a surface, such as, for example, a flat surface or a curved surface. In one embodiment, multiple nozzles are used simultaneously to rapidly deposit the precursor component on the surface. In this way any pattern that can be conceived can be printed, and different nozzles can deposit different precursors, which can be reacted or without reaction. In addition, the method can cure the precursors, such as, for example, by using heat, light or by the addition of a catalyst, to fuse, polymerize or further polymerize the precursors during ink jet printing, and / or after ink jet printing is completed. In one embodiment, the surface is a non-adhesive surface, and the cured sheet filter media is removed by simply detaching the sheet filter media from the surface. For example, a Teflon® surface (® Teflon is a registered trademark of Dupont Corp.), ie, polytetrafluoroethylene (PTFE), or a substrate coated with a non-adhesive coating may be used. In alternative embodiments, the nozzles are oscillated or moved in a predetermined pattern to cause the continuous fibrous material to exit the nozzles to be deposited on the surface in a pattern. For example, the pattern can force the threads to cross each other, merging the threads together. Alternatively, the strands can be deposited in lines and then the table can be rotated behind the strands, and a second step can be made to cause a second pattern of lines to cross through the first pattern of lines. The strands can then be fused using heat or by any other method, such as, for example, degradation by photopolymerization. Alternatively, the process can be a continuous process using a conveyor belt to move the deposition surface from one set of nozzles to the next set of nozzles. Different precursor materials can be deposited by different nozzles in layers (and non-adjacent layers) that can be fused together. In one example, cross junctions are formed with some junctions that will join and others that will not join, allowing a three-dimensional structure to form by extending a two-dimensional sheet filter in a third dimension. Very intricate bi- and three-dimensional patterns can be formed by selectively fusing certain points between alternating layers of a filter medium with multiple layers deposited by the nozzles using this method. In another method, laser printing technology is used to deposit precursors on a surface, which are then polymerized. The precursors are deposited using plates or rollers that impart a static charge to an organic pigment to form a pattern that is then transferred to a transfer surface. The organic filter pattern can contain the precursors or can be used to form the precursors in patterns as mentioned above. In yet another embodiment, the feed also contains a blowing or foaming agent. Any conventional blowing or foaming agent may be incorporated into the fibers therein. Once a fluted structure is formed, the fibrous strands extend, creating hollow fibers, porous fibers or a combination of the two. The advanced filtering methods and media presented herein provide a production of micro-filters and designed sub-micron filters that have a specific pore size, configuration and distribution, which reduce pressure drop and increase capture efficiency compared to conventional filters that have randomly oriented fibers. Also, conventional filters, with random distribution of fibers, require more material to carry out the same level of filtration, increasing the cost of the filter. One or more of these filter media can be coated with a neutralizing component that is capable of neutralizing one or more harmful substances, such as for example, harmful particles, aerosols, gases, vapors and pathogens. The advanced filters of the present invention can be used in any and all filtration systems, such as, for example, HVAC, surgical masks, protective masks, vacuum bags, screens, medical insulation, cleaning rooms, transportation and industrial applications. . It is not possible to list all the combinations that can be used to form the sheet filter means. Although the present invention has been described in relation to particular embodiments and examples thereof, many other variations and modifications and other uses will be apparent to those skilled in the art. It is intended that they be included within the scope of the claimed invention.; therefore, it is preferred that the present invention be limited not only by the specific disclosure herein, but only by the claims provided.

Table I: Relative size of harmful substances

Claims (20)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A filtering means for filtering a noxious substance, characterized in that it comprises: a network of interconnected fibers; and the network of interconnected fibers defines pores that have a pore size distribution designed, not random, where the pore size is not greater than 50 microns.
2. 2. The filter media according to claim 1, characterized in that the pore size distribution is monodisperse.
3. The filter medium according to claim 1, characterized in that the network of interconnected fibers defines a pattern of pores in a honeycomb pattern.
4. 4. The filter medium according to claim 1, characterized in that the network of interconnected fibers defines a pore pattern in a rectangular pattern.
5. 5. A filter medium for filtering a harmful substance, characterized in that it comprises: a network of interconnected fibers; and a neutralizing component, wherein the neutralizing component covers at least a portion of the network of interconnected fibers.
6. The filter medium according to claim 5, characterized in that the network of interconnected fibers is substantially coated by the neutralizing component.
7. The filter media according to claim 5, characterized in that the neutralizing component comprises: a host material; and one or more neutralizing substances.
8. The filter according to claim 7, characterized in that one or more of the neutralizing substances is selected from the group consisting of acidic substances, basic substances and oxidizing substances.
9. The filter according to claim 7, characterized in that the host material has a sticky surface.
10. The filter according to claim 7, characterized in that the host material has a thin layer of viscous organic components.
11. The filter according to claim 7, characterized in that one or more of the neutralizing components comprise at least one oxidizing agent.
12. The filter according to claim 11, characterized in that the oxidizing agent is selected from the group consisting of sodium hypochlorite, calcium hypochlorite, potassium permanganate and mixtures thereof.
13. The filter according to claim 7, characterized in that one or more of the neutralizing components is selected from the group consisting of acidic complexes consisting of acrylic acid derivatives, sulfonic acid derivatives, and mixtures thereof.
14. The filter according to claim 7, characterized in that one or more of the components The neutralizers are selected from the group of basic complexes consisting of sodium alkoxides, tertiary amines and pyridines and compatible mixtures thereof.
15. The filter according to claim 5, characterized in that the fibers are made of a polymeric material such as, for example, poly (vinylpyrrolidone), poly (vinylpyridine), poly (acrylic acid) (free acid or salt), poly (styrenesulfonic acid) ) (free acid or salt), poly (ethylene glycol), poly (vinyl alcohol), polysiloxanes, polyacrylate derivatives, carboxymethylcellulose or mixtures or copolymers thereof.
16. 16. A method for manufacturing a filter medium, characterized in that it comprises: preparing an emulsion or precursor solution; providing pattern to a substrate, wherein a pattern is formed on the surface of the substrate; and contacting the substrate with the emulsion or precursor solution; segregate at least one precursor of the emulsion or solution in the standard on the surface of the substrate; react the precursor that is segregated from the emulsion or solution, forming a filter medium of nox; and removing the filter media from the substrate.
17. The method according to claim 16, characterized in that the step of providing a pattern comprises forming ridges and slits on the surface of the substrate.
18. 18. The method according to claim 17, characterized in that the separation is caused by a temperature difference. The method according to claim 16, characterized in that the surface of the substrate is substantially flat and the step of providing pattern is formed by different materials that will be deposited on the surface of the substrate. The method according to claim 16, characterized in that the step of reacting includes illuminating the precursor with a UV light source to polymerize the precursor.