Super absorbent containing web that can act as a filter, absorbent, reactive layer or fuel fuse

#The invention relates to a web or fiber structure with super absorbent properties. The web, filter, element or medium structures of the invention can also act as a reactive, adsorptive or absorptive layer or in a filtration mode. The structure comprises a fiber web and super absorbent particulate, fiber, fabric or layer. The web can also comprise a reactive, adsorptive or absorptive particulate that also acts as an active particulate, active material fiber, spacer or separation means. The webs of the invention can be used in a number of applications and methods including absorptive, filtration or separation methods.

#Polymer webs can be made by extrusion, melt spinning, air laid and wet laid processing, etc. The manufacturing technology of web structures is vast for obtaining structures that can separate an unwanted, entrained particulate load from a mobile fluid stream. Such materials include filters and separation structures. Filter structures include surface loading media and depth media in which these media can be produced in a variety of geometric structures. Principles relating to the use of such media are described in Kahlbaugh et al., U.S. Pat. Nos. 5,082,476; 5,238,474; 5,364,456 and 5,672,399. In any filter structure containing any arbitrarily selected filtration medium, the filter must remove a defined particle size, and at the same time, have sufficient lifetime to be economically justifiable in its particulate removing properties. Lifetime is generally considered to be the time between installation and the time a filter obtains sufficient particulate load such that the pressure drop across the filter is greater than a predetermined level. An increased pressure drop can cause filter bypass, mechanical filter failure, fluid starvation, or other operating problems. Filtration efficiency is the characteristic of the filtration media that is related to the fraction of the particulate removed from the mobile stream. Efficiency is typically measured by a set test protocol defined below.

#Surface loading filter media often comprise dense mats of fiber having a non-woven structure that is placed across the path of a mobile fluid stream. While the mobile fluid stream passes through the structure of the formed non-woven fibers, the particulate is typically removed from the stream at the filter surface with a certain efficiency and remains on the surface. In contrast to surface loading structures, depth media typically include a relatively (compared to surface loading media) thick structure of fiber having a defined solidity, porosity, layer thickness and efficiency. Depth media and in particular, gradient density depth media are shown in Kahlbaugh et al., U.S. Pat. Nos. 5,082,476; 5,238,474 and 5,364,456. In general, depth media act in filtration operations by impeding the particulate loading in a mobile fluid stream within the filter layer. As the particulates impinge the depth media fibrous structure, the particulate remains within the depth media and is typically distributed onto and held with internal fibers and throughout the filter volume. In contrast, surface loading media typically accumulate particulate in a surface layer.

#FIG. 1 shows the flow diagram of the test system, which was used to measure water concentration of test fuel before and after it was filtered through composite samples

#FIG. 2 shows a cross section view of a composite with a super absorbent particle trapped inside a nanofiber matrix

#FIG. 3 shows the top and cross section views of a composite where nanofibers are used to treat the surface of a super absorbent nonwoven substrate

#The fabric, web, filter, or other flow-through or flow-by structure of the invention can comprise a substantially continuous nanofiber mass and a layer containing the super absorbent particulate, fiber or fabric of the invention. The fabric, fiber and particle or fiber can be made by fiber forming techniques and fabric weaving or nonwoven manufacturing principles. The fiber can be made by forming fiber from a SAP fiber or a combination of polymer and SAP or fiber. Alternatively the SAP or fiber can be added to the fiber after formation. Optionally a reactive, absorptive, or adsorptive fiber spacer or separation means in the form of a particle can be combined with, or otherwise dispersed in, the fiber mass containing the super absorbent. The particulate in a web must contain at least some super absorbent particulate but can also comprise an amount of another particulate or blend of dissimilar particulates. For example, a superabsorbent fiber can be air laid or wet laid into a layer and combined with a nanofiber or other useful layers. In another example, a super absorbent particulate can be used or used when blended with an inert particulate for use in such a layer.

#The inert particulate can comprise a single particulate or can be a blend of inert particulate that differs by composition particle size, particle morphology or some other particle aspect. Similarly, the super absorbent particulate can comprise a mixture of particulates including different active particulates. For example, a super absorbent material can be used with a carbon particulate or could be blended with a zeolite particulate. Alternatively, a carboxy methyl cellulose particulate can be blended with an ion exchange resin particulate in an active layer. Further, such active particulate can have a blended particulate in the sense that particulates of different size, shape or methodology can be combined in the active layers of the invention. The term “entrained particulate” refers to impurities in the mobile fluid while the term “dispersed particulate” refers to the particulate deliberately included within the fiber layers of the invention.

#The web of the invention can be used in one of two separate modes. These modes are designated as “flow-through” or “flow-by”. A single unit can have regions of both modes. In the flow-through mode, the mobile fluid, liquid or gas, passes through the nanofiber layer and substrate in a filtration mode with at least a portion of the flow path as a flow substantially normal to the plane of the fiber layer. Such a flow path can have a tortous route but when contacting the layer is at or near a normal orientation. The entrained particulate can encounter and be removed by the element and as the fluid passes through the layers in contact with the particulate, the particulate can react with absorbed or adsorbed chemical materials suspended or dissolved in the fluid.