None.
The invention relates generally to an apparatus for filtering particulates from a stream of air. More specifically, the invention relates to an air filter having a fiber finish for softening the filter media.
It is desirable to provide filter media in certain streams of air to remove particulates from streams of air because such particulates can cause damage to equipment, for example, HVAC equipment. It is further desirable to inexpensively provide filtering media that has a soft finish because a soft finish causes less irritation.
It is common in the art to use a filtering media that may be made of any of a variety of materials, including, for example, a plurality of glass fibers, or fiberglass. However, fiberglass filter media can be harsh and therefore irritate the skin of one who handles it. Buyers and/or end users of air filters often prefer to avoid such irritation.
One means to combat the irritating harshness often associated with handling fiberglass is to use as a filtering media other types of material, such as, for example, polyester fibers or cotton-polyester fiber blends. Filter media made of polyester fibers or cotton-polyester fiber blends, or possibly other materials, may be considerably less harsh, or softer, than an otherwise similar filter media made of fiberglass. However, it is generally more expensive to produce filtering media composed primarily of polyester fibers or cotton-polyester fiber blends. This added expense can create a problem in the marketplace as buyers and/or end users of air filters often prefer less expensive options.
Thus, it would be highly desirable to make an air filter having a media that simulates the soft feel of polyester fiber or cotton-polyester fiber blends and therefore limits the irritating effects of handling it, while simultaneously maintaining the lower cost of production enjoyed when producing fiberglass filter media.
The present disclosure is directed towards inventive methods and apparatus for an air filter with a tactile fiber finish. The air filter with a tactile fiber finish is, in various embodiments, a filter media comprising a plurality of glass fibers that may be supported by a frame. The glass fibers have deposited thereon a binding agent to facilitate bonding of the fibers thus forming the filter media, as well as a finishing agent that reduces the harshness of the fibers.
Generally, in one aspect, a tactile air filter is provided for reducing the harshness of the fibers, thereby giving the filter a softer feel and reducing irritation to those who handle it. The tactile air filter includes a filter media that is formed of a plurality of glass fibers and the filter media has at least one surface and also an interior. There is a cured base resin that is interspersed over the surface and throughout the interior of the filter media that bonds the glass fibers together. There is also a layer of tactile fiber finish that is that is interposed between the cured base resin and the ambient air. The tactile fiber finish layer is bonded to the cured base resin and encapsulates the base resin and the glass fibers. The tactile fiber finish layer is interspersed over the surface and throughout the interior of the filter media.
In some embodiments, the cured base resin is urea formaldehyde.
In some embodiments, the fiber finish layer is a film of hydrocarbon resulting from the melting of polybutene polymer.
In some embodiments, the cured base resin has a dry base resin component and the fiber finish has a dry fiber finish component. In these embodiments, the web of glass fibers has a weight of approximately 1.8 to 4 times the weight of the dry base resin component and the dry fiber finish component has a weigh approximately 2% of the weight of the dry base resin component.
In some embodiments, there is also a frame that frames the filter media, the cured base resin, and the fiber finish layer.
In some embodiments, the frame includes a truss structure that at least partially covers at least one surface of the filter media.
In some embodiments, the filter media is compressed by the frame in at least one direction, thereby creating a friction fit.
In some embodiments, the compressed filter media is also adhered to the frame to help secure the filter media in fixed relation to the frame.
In some embodiments, the layer of fiber finish softens the fiberglass filter media to provide a tactile feel similar to polyester fiber air filter media.
Generally, in another aspect, a method of forming a tactile air filter is provided. The method includes forming a web of glass fibers into a filter media suitable for filter a fluid flow. The method also includes atomizing a base resin. The method further includes spraying the atomized base resin from a spray head toward the web of glass fibers during the forming of the filter media. The method includes dripping fiber finish into the base resin spray thus the fiber finish and base resin spray agglomerate into a separate binary composite. The method also includes depositing the separate binary composite on the filter media. The method further includes curing the base resin on the filter media at a temperature sufficiently high to melt the fiber finish, thereby melting the fiber finish. The cured base resin is adhesive enough to bond to the glass fibers and to bond the glass fibers to one another. During curing, the melted fiber finish has a low enough surface energy in relation to the surface energy of the base resin to migrate to an outer position relative to the glass fibers, thereby forming an outer fiber finish layer.
In some embodiments, the separate binary composite is deposited on the web of glass fibers during the forming of the filter media.
In some embodiments, the separate binary composite is deposited on the web of glass fibers after the forming of the filter media.
In some embodiments, the glass fibers each have a diameter of approximately 5 to 50 microns.
In some embodiments, the base resin is substantially urea formaldehyde.
In some embodiments, the fiber finish is substantially polybutene polymer and the fiber finish layer is substantially a hydrocarbon film.
In some embodiments, the base resin has a dry base component and the fiber finish has a dry fiber finish component. In these embodiments, the web of glass fibers has a weight approximately 1.8 to 4 times the weight of the dry base resin component and the dry fiber finish component has a weight approximately 2% of the weight of the dry base resin component.
In some embodiments, the base resin is thermosetting and is cured to the glass fibers for approximately 0.5 to 2 minutes.
In some embodiments, the thermosetting base resin is cured at a temperature of approximately 300 to 650 degrees Fahrenheit.
In some embodiments, the fiber finish is dripped at a volumetric rate approximately equal to 2% of a volumetric spray rate of the atomized base resin spray.
In some embodiments, the volumetric spray rate of said atomized base resin spray is approximately 100-200 cubic centimeters per minute.
In some embodiments, the atomized base resin spray that is sprayed at a volumetric spray rate of approximately 100-200 cubic centimeters per minute is sprayed at a velocity of approximately 100-500 feet per second.
Generally, in another aspect, a method of forming a tactile air filter is provided. The method includes forming a web of glass fibers into a filter media suitable for filtering a fluid flow. The method also includes atomizing a base resin and atomizing a fiber finish. The method further includes spraying the atomized base resin through a first port of a spray head and spraying the atomized fiber finish through a second port of the spray head toward the web of glass fibers, so that the two sprays agglomerate into a separate binary composite. The method includes depositing the separate binary composite on the web of glass fibers. The method also includes curing the base resin on the filter media at a temperature sufficiently high to melt the fiber finish, thereby melting the fiber finish. The cured base resin is adhesive enough to bond to the glass fibers and to bond the glass fibers to one another. During curing, the base resin is viscous enough relative to the melted fiber finish to migrate to an inner position that is proximate to the glass fibers, thereby displacing the melted fiber finish to an outer position thereby forming an outer fiber finish layer.
In some embodiments, the separate binary composite is deposited on the web of glass fibers during the forming of the filter media.
In some embodiments, the separate binary composite is deposited on the web of glass fibers after the forming of the filter media.
In some embodiments, the glass fibers each have a diameter of approximately 5 to 50 microns.
In some embodiments, the base resin is substantially urea formaldehyde.
In some embodiments, the fiber finish is substantially polybutene polymer and the fiber finish layer is substantially a hydrocarbon film.
In some embodiments, the base resin has a dry base component and the fiber finish has a dry fiber finish component. In these embodiments, the web of glass fibers has a weight approximately 1.8 to 4 times the weight of the dry base resin component and the dry fiber finish component has a weight approximately 2% of the weight of the dry base resin component.
In some embodiments, the base resin is thermosetting and is cured to the glass fibers for approximately 0.5 to 2 minutes.
In some embodiments, the thermosetting base resin is cured at a temperature of approximately 300 to 650 degrees Fahrenheit.
In some embodiments, the atomized fiber finish is sprayed at a volumetric rate approximately equal to 2% of a volumetric spray rate of the atomized base resin spray.
In some embodiments, the volumetric spray rate of said atomized base resin spray is approximately 100-200 cubic centimeters per minute.
In some embodiments, the atomized base resin spray that is sprayed at a volumetric spray rate of approximately 100-200 cubic centimeters per minute is sprayed at a velocity of approximately 100-500 feet per second.
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
It is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “bonded” and “attached” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “bonded” and “attached” and variations thereof are not restricted to physical or mechanical connections or couplings.
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In some embodiments, a sufficient amount of the atomized base resin is sprayed from the spray nozzle 334 with sufficient velocity to have enough inertia to carry the separate binary composite to the fiber mat 280. In some embodiments, the atomized base resin is sprayed at a volumetric rate of approximately 100 to 200 cubic centimeters (cc) per minute at a velocity of approximately 100 to 500 feet per second (fps) and the fiber finish drips at a volumetric rate wherein the dry fiber finish component is approximately equal to 2% of the volumetric rate of the dry component of the base resin. In an illustrative example, which is provided only as an illustration and is not to be construed as a limitation, 200 cc per minute of atomized base resin at 50% dry component (i.e. 100 cc per minute dry base resin component) is sprayed at a velocity of 100-500 fps toward the fiber mat 280, and the fiber finish is dripped at a rate of 4 cc per minute at 50% dry component (i.e. 2 cc per minute dry fiber finish component). In this illustrative example, the ratio of base resin to glass fiber may be 20-35% binder to 65-60% glass fiber, and the glass fiber may be produced and/or introduced at a rate of approximately 40 pounds of glass fiber per hour. It is understood that the constituents may be dripped at other rates and/or velocities and that the ratio of dry fiber finish component to dry base resin component is not limited to 2%, but the ratio may be higher or lower than 2%. In some embodiments, the spray from the spray nozzle may produce droplets having sub-millimeter diameters, or diameters in the micron range. In some embodiments, the drip may produce droplets having a diameter of 0.5 to 7 mm. It is understood that other diameters of droplets may be produced and/or used without substantially deviating from the disclosure herein. In some embodiments the base resin is transported in a liquid state from the base resin supply 330 to the spray head 320 via the first supply line 332. The base resin may contain a dry component, for example substantially dry urea formaldehyde that is mixed with water, or any of a variety of other liquids, to form the base resin. Similarly, a dry fiber finish component, for example substantially dry polybutene polymers, may be emulsified in water to form the tactile fiber finish. The dry base resin component and/or the dry fiber finish component may be in a powdered form to facilitate mixing and/or combining with water, but it is understood that they do not need to be in a powdered form. In some embodiments, it may be advantageous to use dripping equipment that is somewhat separated from the spraying equipment, as this would allow the dripping equipment to be assembled and disassembled independently of the spraying equipment, which may be preferable to avoid disturbing the spraying equipment settings and therefore ensure a continued precise dosing ratio of base resin to glass fiber.
In some embodiments the tactile fiber finish may be atomized and sprayed, instead of dripped, similarly to how the base resin is atomized and sprayed in the embodiment discussed above. In these embodiments, the tactile fiber finish and base resin are transported to the spray head via separate supply lines, separately atomized, and sprayed through one spray nozzle, or through separate but proximate spray nozzles, so the atomized base resin and atomized fiber finish agglomerate into a separate binary composite that is transferred to the fiber mat. In embodiments having a tactile fiber finish spray instead of drip, the separate binary composite may agglomerate into a finer spray, which may advantages and/or disadvantages that are readily apparent and understood in the art. Thus, either class of embodiments may be readily and advantageously utilized. It may be advantageous to keep the base resin from contacting the fiber finish until one or both of the constituents is sprayed, as this will allow for the base resin and fiber finish to be more evenly distributed on and throughout the fiber mat 280. Otherwise, if the base resin and the fiber finish are combined prior to spraying, there will be time for the constituents to separate prior to spraying, thus the constituents would be less evenly distributed on the fiber mat 280. In some embodiments, it may be advantageous to use fiber finish spraying equipment that is somewhat separated from the base resin spraying equipment, as this would allow the fiber finish spraying equipment to be assembled and disassembled independently of the base resin spraying equipment, which may be preferable to avoid disturbing the base resin spraying equipment settings and therefore ensure a continued precise dosing ratio of base resin to glass fiber.
The foregoing description of several embodiments of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention and all equivalents be defined by the claims appended hereto.