Patent Description:
Disposable wipes or wipers are often used in place of durable cloths in a variety of cleaning situations and can provide cost advantages over durable cloths. In industrial cleaning settings, disposable wipers are commonly used to clean equipment, machinery, parts, and work surfaces and in the process, may come in contact with and accumulate materials such as industrial oil, solvents, and grease, among others. In such a setting, disposable wipers can provide multiple benefits over durable wipes. For example, disposable wipers can provide a convenience advantage over durable cloths in that the disposable wipers need not be re-washed or decontaminated, whereas durable cloths need to be collected and then sent to traditional cleaning sites for washing and decontamination. Because the durable cleansing clothes often have a variety of contaminates with very different chemical and physical properties, it is difficult to provide a single cleaning method or procedure that can effectively remove all of the contaminates, which can leave some contaminates on the cleansing cloths. Additionally, disposable wipers provide the benefits of providing fresh and soft wiper surfaces for each use, avoiding metal accumulation after repeated uses, and providing potential cost advantages over durable cloths.

However, one obstacle of using disposable wipers in place of durable cloths is that the disposable wipers are typically discarded after becoming soiled and if the wipers contain designated hazardous materials, the disposable wipers must be handled properly in compliance with federal and state hazardous waste regulations. The handling that may be required can include several processing steps such as the collection, storage, and transportation of used wipers. These steps can minimize the benefits and advantages of using disposable wipers over durable cleansing cloths.

Thus, there is a desire for a method for cleaning fibers and/or filaments from contaminated articles, such as disposable wipers, such that the fibers can be recycled instead of being treated and disposed of as solid waste. There is also a desire for a method of recycling fibers and/or filaments from contaminated articles such that the fibers and/or filaments can be reused to manufacture new articles.

Methods for using magnetic separation to deink and remove "stickies" from recycled paper pulp are described by <CIT> and <CIT>. <CIT> relates to a magnetic separation and deinking method for waste paper.

The present invention provides a method for cleaning fibers from a contaminated article as stated in claim <NUM>.

A full and enabling disclosure thereof, directed to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the appended figures in which:.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the disclosure.

In an embodiment, the present disclosure is generally directed towards a method for cleaning fibers from a contaminated article involving the addition of magnetic particles. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment or figure can be used on another embodiment or figure to yield yet another embodiment. It is intended that the present disclosure include such modifications and variations.

When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles "a", "an", "the" and "said" are intended to mean that there are one or more of the elements. Many modifications and variations of the present disclosure can be made without departing from the spirit and scope thereof. Therefore, the exemplary embodiments described above should not be used to limit the scope of the invention.

The term "contaminates" refers herein to solids and fluids, both organic and inorganic that can be absorbed, adsorbed, or contained by an article. Exemplary contaminates can include, but are not limited to, pure metals and alloys, which can be in the form of particles from metallic surfaces; hybrid inorganic and organic composites and mixtures, such as greases, lubricants and surface coatings; inorganic materials, such as metal halides, sulfates, carbonates, hydroxides, sulfides, metal oxides, organometallics, ceramics; and organic materials, such as liquid organic solvents, oils, and grease without lubricants.

The term "hydrophilic" refers herein to fibers or the surfaces of fibers which are wetted by aqueous liquids in contact with the fibers. The degree of wetting of the materials can, in turn, be described in terms of the contact angles and the surface tensions of the liquids and materials involved. Equipment and techniques suitable for measuring the wettability of particular fiber materials or blends of fiber materials can be provided by Cahn SFA-<NUM> Surface Force Analyzer System, or a substantially equivalent system. When measured with this system, fibers having contact angles less than <NUM> are designated "wettable" or hydrophilic, and fibers having contact angles greater than <NUM> are designated "nonwettable" or hydrophobic.

The term "meltblown" refers herein to fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity heated gas (e.g., air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which can be a microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in <CIT>, which is incorporated herein by reference. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than about <NUM> denier, and may be tacky and self-bonding when deposited onto a collecting surface.

The term "nonwoven" refers herein to materials and webs of material which are formed without the aid of a textile weaving or knitting process. The materials and webs of materials can have a structure of individual fibers, filaments, or threads (collectively referred to as "fibers") which can be interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven materials or webs can be formed from many processes such as, but not limited to, meltblowing processes, spunbonding processes, carded web processes, etc..

The term "spunbond" refers herein to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine capillaries of a spinnerette having a circular or other configuration, with the diameter of the extruded filaments then being rapidly reduced by a conventional process such as, for example, eductive drawing, and processes that are described in <CIT>, <CIT>, <CIT>, <CIT> and <CIT>, <CIT>, <CIT>, and <CIT>, each of which is incorporated herein in its entirety by reference. Spunbond fibers are generally continuous and often have average deniers larger than about <NUM>, and in an embodiment, between about <NUM>, <NUM> and <NUM> and about <NUM>, <NUM> and <NUM>. Spunbond fibers are generally not tacky when they are deposited on a collecting surface.

The term "wiper" or "wipe" refers herein to a non-woven or woven article generally used in cleaning or wiping applications. "Wipers" or "wipes" generally include at least some percentage of pulp fibers, but a non-woven or woven article including no pulp fibers can be a "wiper" or "wipe" as used herein. "Wipes" and "wipers" as discussed herein can include fibers and/or filaments other than pulp fibers, including, but not limited to, polypropylene staple fibers or filaments. Exemplary "wipers" or "wipes" include industrial cleaning wipers and paper towels. The term "wiper" can be synonymous with "wipe.

Referring to <FIG>, an exemplary method <NUM> for cleaning fibers from a contaminated article is illustrated. The method <NUM> can include providing a contaminated article comprising contaminates and at least one of fibers and filaments. While the method <NUM> discussed herein can be conducted for a single wiper, it is preferable to clean fibers from a plurality of contaminated articles simultaneously for efficiency purposes. The method <NUM> as discussed herein can be conducted on a small scale (e.g., several grams to several hundred grams) or can be scaled up to a commercial operation for cleaning fibers from larger quantities of contaminated articles (e.g., several hundreds of kilograms to several tongs or more). Some of the exemplary discussion provided herein was for testing conducted at a small scale.

In an embodiment, the contaminated article can be a used wiper, or wipe. For example, small scale testing was conducted according to the method <NUM> using prepared wet-laid handsheets that included about <NUM>-<NUM>% pulp fibers and about <NUM>-<NUM>% polypropylene staple fibers. This <NUM>-<NUM>/<NUM>-<NUM> pulp/polypropylene ratio was prepared simulate a sample industrial wiper, such as WypAll* industrial wipers manufactured by Kimberly-Clark Professional. The WypAll* industrial wiper manufactured by Kimberly-Clark Professional include about <NUM>-<NUM>% pulp fibers and about <NUM>-<NUM>% spunbond polypropylene fibers. The prepared wet-laid handsheets may be referred to as a wiper, or wipe, throughout this disclosure.

Thus, in one embodiment, the method <NUM> can be utilized for cleaning a non-woven article including pulp fibers and polymer fibers, however, in accordance with the claims the method <NUM> can also be utilized for cleaning contaminated articles including pulp fibers and polymeric filaments. The prepared wet-laid handsheets include a ratio of pulp fibers to polymeric fibers of about <NUM>, but the method discussed herein can be used to clean contaminated articles including other ratios of pulp fibers to polymeric fibers or filaments. In examples, the method <NUM> can be used with contaminated articles including about <NUM>-<NUM>% pulp fibers and about <NUM>-<NUM>% polymeric fibers or filaments, more preferably about <NUM>-<NUM>% pulp fibers and about <NUM>-<NUM>% polymeric fibers or filaments. Thus, it is contemplated that the contaminated article used in the method <NUM> discussed herein could include non-woven articles including ratios of pulp fibers to polymeric fibers or filaments of at least about <NUM>, more preferably, at least about <NUM>, and even more preferably, at least about <NUM>. In accordance with the claims the contaminated article is a non-woven article comprising pulp fibers and at least one of polymeric fibers and polymeric filaments.

For the small scale testing conducted for method <NUM>, prepared handsheets were soiled with an oil/grease mixture to test various conditions for method <NUM>. To simulate used industrial wipers, a used oil/grease mixture was made that included about <NUM> grams of used motor oil and about <NUM> grams of Valvoline® Moly-Fortified Multi-Purpose Grease, for an approximate <NUM>/<NUM> ratio of oil/grease. The used motor oil was collected by a motor repair/oil change shop and was used as received. Three prepared handsheets having a total dry weight of approximately <NUM> grams were then soiled with the used oil/grease mixture by first spreading the pre-made used oil/grease mixture onto a clean, stainless steel plate and then the three prepared handsheets were used to wipe off all of the used oil/grease mixture. Each of the three prepared handsheets were exposed to a similar amount of the used oil/grease mixture. After exposure to the used oil/grease mixture, the three prepared handsheets were placed in an open container for at least one hour to allow the settling of the used oil/grease into the handsheets' interior matrices before any small scale testing was conducted with the handsheets using method <NUM>.

The method <NUM> can include a pre-pulping preparation step <NUM>, in which large pieces of non-wiper related materials (e.g., large metal shavings, wood pieces, machine parts, and other objects) can be separated from contaminated wipers either manually, mechanically, and/or automatically. In some embodiments, the pre-pulping preparation step <NUM> can be a pre-washing of the contaminated articles in which the contaminated article(s) can be placed in a container in a pre-washing solution and agitated. The pre-washing solution can be water. The pre-pulping preparation <NUM> can provide for some contaminates, such as oils, greases, and organics, to be released and rise to the top of the pre-washing solution, while other contaminates, such as metal shavings, saw dust, inorganics, and dirt can drop to the bottom of the pre-washing solution in the container. While preferred, the pre-pulping preparation <NUM> of the contaminated article(s) is not necessary to the method <NUM> described herein. If pre-washing is performed as pre-pulping preparation <NUM>, the excess pre-washing solution <NUM> used can be directed to a waste-water facility <NUM> for further processing.

The method <NUM> can also include adding a plurality of magnetic particles <NUM>. Adding the magnetic particles <NUM> can be completed by adding the magnetic particles to a solution in which the contaminated articles will be placed. Alternatively or additionally, adding the magnetic particles <NUM> can be completed by adding the magnetic particles directly to the contaminated article(s). In a first embodiment, the method <NUM> can include adding a plurality of magnetic particles <NUM> to a solution, such as water, in which the contaminated articles will be pulped <NUM> in as part of method <NUM>, which will be further described below. In a second embodiment, the method <NUM> can include adding a plurality of magnetic particles <NUM> directly to the contaminated articles before the contaminated articles are pulped <NUM> in method <NUM>.

Various magnetic particles can be added <NUM> to the solution or directly to the wipe. For example, in the small scale testing conducted, the magnetic particles added <NUM> included iron powder, and/or black iron oxide. In some embodiments, magnetically weak lead oxide particles can also be added in addition to iron powder and/or iron oxide particles, which have stronger intrinsic magnetic properties. Adding magnetic particles with strong magnetic susceptibility can function as the "seeds" for the magnetic removal of magnetic particles and/or metal containing contaminates with weak magnetic susceptibility. The "seeds" as used herein can mean that when magnetic particles with strong magnetic susceptibility are in mixed states with other magnetic particles with weak magnetic susceptibility, the magnetic particles with strong magnetic susceptibility will bring at least some of the magnetic particles and/or metal containing contaminates with weak magnetic susceptibility to the magnet surface so that the latter can also be magnetically removed. As used herein, mixed states can mean that they are either physically aggregated together by charge-charge interactions or bound together by the existence of oil and grease. Here, oil and grease, particularly the adhering, or sticky, portions of oil and grease, can effectively function as a binder or a trap to harbor together any metal containing contaminates with varied magnetic susceptibilities. Of course, it is contemplated that other particles/substances exhibiting magnetic behavior other than iron, iron oxide, and lead oxide can be utilized for method <NUM>.

This "seed" functionality was demonstrated by first preparing a three liter water suspension with <NUM> ppm of iron powder, <NUM> ppm black iron oxide, and <NUM> ppm lead oxide and then a six inch bar magnet (as described further below) was placed into the suspension under stirring by an IKA <NUM>-<NUM> RPM variable speed mixer with a Teflon blade. It was observed that intrinsically magnetically strong particles of iron and iron oxide were quickly pulled to the magnet surface to form black rings and then slowly the intrinsically magnetically weak lead oxide particles coated onto the already formed black iron/iron oxide rings. The black rings iron and iron oxide rings gradually became pinkish to assume the color of lead oxide particles. From this demonstration, it was understood that some very fine magnetically strong iron/iron oxide particles can be absorbed onto lead oxide particles in the suspension and they then will be pulled to magnet's surface, albeit at a much slower speed than iron/iron oxide.

As briefly discussed above, adding the plurality of magnetic particles <NUM> can be completed by adding the magnetic particles to water. The plurality of magnetic particles <NUM> can be added to the water in various concentrations, such as <NUM> parts per million ("ppm"), <NUM> ppm, <NUM> ppm, <NUM> ppm, and <NUM> ppm. It is contemplated that the plurality of magnetic particles can be added <NUM> at concentrations outside of these sample concentration levels. In the small scale testing conducted for demonstrating method <NUM>, adding the plurality of magnetic particles <NUM> was prepared by adding the following amounts of iron powder, black iron oxide, and lead oxide to three liters of water to provide the following concentrations, as shown in Table <NUM> below. As an example, to provide <NUM> ppm of iron powder to a solution of three liters of water, <NUM> grams of iron powder are added to three liters of water.

However, the method <NUM> can also including adding the magnetic particles <NUM> directly to the contaminated article(s), or commonly referred to as "spiking" the contaminated article(s). In one embodiment and for purposes of the small scale testing conducted herein, the magnetic particles were added to the oil grease/mixture as described above that was used to simulate the used wipers in order to add the magnetic particles to the three prepared handsheets, the simulated contaminated articles. Of course, it is contemplated that the magnetic particles could be added <NUM> to the contaminated article(s) in other ways. For example, the magnetic particles can be added <NUM> to the wipers by dry mixing the wipers with the magnetic particles. Alternatively, the magnetic particles can be added <NUM> to the wipers during manufacturing of the wipers such as during the extrusion process, or during air-laid or wet-laid processes by adding the dry magnetic particles or placing them in the process water. In yet another alternative, the magnetic particles can be added <NUM> on to the wipers by printing or spraying a coating formulation containing the magnetic particles.

The method <NUM> can further include pulping <NUM> the contaminated article(s). Pulping <NUM> of the contaminated article(s) can be conducted by placing the contaminated article(s) in a solution, which can be water, and agitating and mixing the contaminated article(s) to separate the fibers from the contaminated article(s) to provide dissociated pulped fibers.

Pulping <NUM> can be done by utilizing different pulping tools, depending upon the amount of wipers to be pulped, the fibers comprising the contaminated wipers (e.g., short fibers or continuous fibers), and the manufacturing methods involved (e.g. air-laid or wet-laid with latex or wet strength enhancers as binders, or hydroentangled or co-formed webs with pulp fibers and continuous filaments, etc.). For wipers with only pulp fibers or wipers with pulp and staple fibers, traditional pulpers commonly used in paper industry such as Hollander types or (or Valley beaters) are preferred. In some cases, simple blenders commonly used in food industry may be sufficient for pulping <NUM> a small amount of wipers with only pulp and staple synthetic fibers.

In some circumstances, pulping <NUM> for wipers with continuous filaments (with or without pulp fibers) may not be efficiently pulped by using traditional pulpers used in paper industry as continuous filaments may not be easily broken or cut to short staple fibers. In these instances, special pulpers, such as Tornado types of pulpers, are required to break and/or cut down the continuous filaments to short staple fibers. Tornado pulpers are known to have specially designed motors as well as fiber stretching and cutting mechanisms so that continuous filaments in the wipers can be stretched/cut/pulped.

Although not required by method <NUM>, the solution for pulping <NUM> can be heated during the pulping <NUM> of the contaminated article(s), and more particularly, it is preferable to heat the solution to at least about <NUM>. Not to be bound by theory, but it is believed that heating the solution for the pulping <NUM> provided benefits to help relax the fibrous structure matrix and also increase the solubility as well as the dispensability of both organic and inorganic contaminates in the solution. In particular, contaminates article(s) including polymeric fibers (e.g., spunbond polypropylene fibers) can be softened by such heat, and the softening can lead to relaxation of reduction of entanglement among fibers in the article(s).

In the small scale testing conducted for method <NUM>, the pulping <NUM> was performed by adding the three prepared handsheets (weighing approximately <NUM> grams each) to <NUM> of water and blending with a high speed blender, such as a ten speed Oster® Osterizer kitchen blender, at a setting of "liquify", for approximately two minutes. After this blending, the blended mixture was transferred to a five liter beaker <NUM> (see <FIG>) equipped with an IKA <NUM>-<NUM> RPM variable speed mixer with a Teflon blade. Water was added to the five liter beaker <NUM> such that blended wipes, contaminates, and added magnetic particles provided three liters of such a solution. In such an example, the fiber consistency was approximately <NUM>-<NUM>% and the fiber/oil/grease consistency level was approximately <NUM>-<NUM>%. The blended wipes, contaminates, and added magnetic particles were then stirred with the IKA mixer at <NUM> RPM for one to two minutes to form a suspension <NUM> of dissociated pulped fibers, contaminates, and magnetic particles. The pulping <NUM> of the contaminated article(s) can be conducted in the same manner regardless of how the plurality of magnetic particles are added <NUM> (either adding the magnetic particles <NUM> to the solution before, during, or after the pulping <NUM> or adding the magnetic particles <NUM> directly in the contaminated article(s)).

The method <NUM> can also include applying a magnetic field <NUM> to the suspension <NUM> of dissociated pulped fibers and the contaminates. Applying the magnetic field <NUM> to the suspension <NUM> can occur simultaneously to pulping <NUM> the contaminated article(s) and/or after the pulping <NUM> of the contaminated article(s). In a preferred embodiment, the magnetic field is applied <NUM> to the suspension while the pulping <NUM> of the contaminated article(s) is being performed to separate the dissociated pulped fibers and the contaminates from the contaminated article(s). In one embodiment, applying the magnetic field <NUM> can be completed by providing a magnet <NUM> to be at least partially submerged in the suspension <NUM>, as illustrated in <FIG>. In the small scale testing conducted, the magnetic field was applied <NUM> by dipping the magnet <NUM> in the beaker until it hit the bottom of the beaker <NUM>. Of course, it is contemplated that the magnetic field could also be generated by providing an electromagnetic field as an alternative to, or in addition to, one or more magnets <NUM>.

Without being bound by theory, it is believed that added magnetic particles <NUM> preferably interact with oils/grease in a contaminated article during pulping <NUM>. The high viscosity of oil/grease could help to capture or trap the magnetic particles better than fibers. Besides the magnetic particles that are added <NUM>, oils/grease can also capture or trap other inorganics such as metal shavings, ceramics, oxides, and lubricants. In addition, hydrophobic fibers such as pulped staple polypropylene fibers from spunbond can also be trapped and captured into oils/grease because of their strong affinity through hydrophobicity. Additionally, used wipers from industrial cleaning may already have low levels of magnetic metal containing contaminates (generally lower than <NUM>-<NUM> ppm) that can be removed by a magnetic field. Taken collectively, the above described mechanisms will lead to the formation of magnetically attractive aggregates that contain various forms of contaminates and hydrophobic fibers (e.g., oil, grease, magnetic particles, all other metal containing contaminates, and hydrophobic fibers) that can be removed by a magnetic field. It is conceivable that if a sufficient amount of magnetic particles are added <NUM> in method <NUM>, most contaminates (e.g. up to <NUM>-<NUM>%) in the contaminated article(s) can be removed by using a magnetic field alone without involving traditional detergent-based cleaning methods.

As described above, aggregates with all forms of contaminates and magnetic particles can accumulate on the magnet <NUM> due to the magnetic field being applied <NUM> to the suspension <NUM> including the dissociated pulped fibers. This accumulation can also include hydrophobic spunbond fibers, and conceivably some hydrophilic pulp fibers. As the contaminates accumulate on the magnet <NUM> (either directly to the magnet surface and/or indirectly via hydrophobic fibers or the added magnetic particles <NUM> that are attracted themselves to the magnets), the magnet <NUM> can periodically be removed from the suspension <NUM> such that the contaminates can be removed <NUM> from the suspension. For example, in the small scale testing conducted, the magnet <NUM> was removed from the suspension <NUM> every five minutes such that that the collected contaminates and the added magnetic particles and fibers (which can also include contaminates) (such as illustrated on the magnet <NUM> in <FIG>) can be removed <NUM>. It is not required that the collected contaminates and the added magnetic particles and fibers can be removed <NUM> in other time intervals and sequences. Of course, it is contemplated that the contaminates, and the added magnetic particles and fibers could be removed <NUM> from the suspension in other ways, such as by keeping the magnet <NUM> stationary and draining the suspension <NUM>. This alternative method could also allow access to the magnet <NUM> to remove the contaminates, added magnetic particles and fibers from the surface of the magnet <NUM>.

In the small scale testing conducted, the collected contaminates, added magnetic particles, and fibers were removed <NUM> from the magnet <NUM> by using one or two wipes, such as a Kimwipe manufactured by Kimberly-Clark Professional, to wipe the surface of the magnet <NUM> clean. These wipes used to remove the collected contaminates, added magnetic particles, and fibers were weighed prior to removing such contaminated, added magnetic particles, and fibers, such that amount of contaminates, magnetic particles, and fibers could be weighed each time the surface of the magnet <NUM> was wiped clean during the small scale testing. Of course, the collected contaminates, added magnetic particles, and fibers can be removed <NUM> from the magnet <NUM> by other means, including, but not limited to, pressurized water jets, pressurized air guns, etc..

In some embodiments, the magnet <NUM> can be reapplied to the suspension <NUM> to continue to attract additional contaminates, the added magnetic particles <NUM>, and hydrophobic fibers, which can be removed <NUM> from the suspension <NUM> via the same process as just described. In some circumstances, the magnetic field can be applied <NUM> several times and removed from the suspension <NUM> several times, until a substantial portion of the plurality of the added magnetic particles and contaminates from the suspension are removed <NUM>. For purposes of data collection in the small scale testing, the collected wet mass wiped from the magnet <NUM> surface was collected on filter paper, dried at <NUM> for about forty-eight hours, and were recorded for efficacy analyses, which will be described further below.

In the small scale testing conducted, the magnet <NUM> was a rare earth magnet, a six inch long and one inch in diameter neodymium-iron-boron separator bar magnet, available from Amazing Magnets. The magnet <NUM> included an assembly of multiple individual magnets encased within a stainless steel housing with the individual magnets being placed within the housing with like poles opposing one another. The specifications provide that the surface magnetic field strength provided by the magnet can be at least <NUM>,<NUM> Gauss on at least some parts of the stainless steel tube surface of the magnet.

Of course, it is contemplated that different sizes and types of magnets providing different magnetic field strengths can be used to apply the magnetic field <NUM> for method <NUM>. It is preferable, however, that the magnetic field strength is at least <NUM> Gauss. It is also contemplated that more than one magnetic field could be applied <NUM> to the suspension <NUM> of dissociated pulped fibers, for example, by at least partially submerging two or more magnets <NUM> to the suspension <NUM> simultaneously. By applying <NUM> more than one magnet field to the suspension of dissociated pulped fibers, the time required for the method <NUM> of cleaning the fibers from a contaminated article(s) could be decreased. As mentioned above, it is contemplated that the magnetic field could also be generated by providing an electromagnetic field as an alternative to, or in addition to, one or more magnets <NUM>.

The magnetic field applied by the magnet <NUM> was measured prior to applying the magnetic field <NUM> in the method <NUM> using a Model <NUM>-ST DC Gauss meter made by AlphaLab, Inc. , which can measure strength and polarity of magnetic fields up to <NUM>,<NUM> Gauss, with a resolution of <NUM> Gauss. As shown in Table <NUM> below, the strength of the magnetic field can decrease away from the surface of the magnet <NUM>, as seen from the magnetic field strength values measured one inch away from the surface of the magnet <NUM>. Additionally, the strength of the magnetic field can vary along the surface moving between the magnetic poles of the individual magnets within the magnet <NUM>. In the magnet <NUM> used in the small scale testing, it can be seen from measuring the magnetic field strength that six "rings" of magnetic field strength were created that were greater than <NUM> Gauss. Looking at <FIG>, these changes in magnetic field strength creating "rings" are depicted in the amount of contaminates, added magnetic particles, and fibers that are attracted to the surface of the magnet <NUM> as the magnet <NUM> is lifted from the suspension <NUM> and the contaminates, magnetic particles, and fibers are removed <NUM> from the suspension <NUM>. It is preferable to have at least some portion of the magnetic field being applied <NUM> have a magnetic field strength of at least <NUM> Gauss, as the stronger the magnetic field, the more likely the contaminates, added magnetic particles attracted to contaminates, and fibers containing contaminates will be attracted to the magnetic field and stay attached during the removing <NUM> of such contaminates, particles, and fibers.

The magnet <NUM> can be set-up as a stationary or mobile fixture. In some circumstances, stationary types may be preferred due to their rigidity and robustness. However, a mobile set-up for the magnet <NUM> can also have advantages for later stages of contaminate removal. For example, when only a small amount of remaining aggregates of oil/grease/magnetic particles/fibers are floating on the top of the suspension <NUM>, a mobile set-up for the magnet <NUM> can be advantageous to provide for more contact with the contaminates that are no longer homogenously distributed in the suspension <NUM>.

As illustrated in <FIG>, the method <NUM> can also include filtering <NUM> the dissociated pulped fibers after removing <NUM> at least some of the plurality of magnetic particles and at least some of the contaminates from the suspension <NUM>. The filtering <NUM> can be accomplished by running the suspension <NUM> through a sieve, or any other known filtering equipment. Filtering <NUM> the dissociated pulped fibers, while preferred, is not a required aspect of the disclosure. Recovered pulped fibers from filtering <NUM> can be substantially free from any major dark colored oil/grease/magnetic particles.

The method <NUM> can also include rinsing <NUM> the dissociated pulped fibers after removing <NUM> a at least some of the plurality of magnetic particles and at least some of the contaminates from the suspension <NUM>. The rinsing <NUM> can provide the benefit of removing any contaminates confined in the dissociated pulped fibers that were not removed by filtering <NUM> or by applying the magnetic field <NUM> to the suspension <NUM> and removing <NUM> the contaminates, magnetic particles, and fibers attracted to the magnetic field <NUM> as discussed above. As illustrated in <FIG>, the rinsing solution <NUM> can be transferred to a waste-water facility <NUM> for further processing after rinsing the dissociated pulped fibers. In some embodiments, it may be preferable to perform the rinsing <NUM> several times.

The method <NUM> can include drying <NUM> the dissociated pulped fibers after removing <NUM> at least some of the plurality of magnetic particles and at least some of the contaminates from the suspension <NUM>. As illustrated in <FIG>, in some embodiments, the drying <NUM> of the dissociated pulped fibers can occur after rinsing <NUM> the dissociated pulped fibers. Drying <NUM> can be performed using either air-drying or providing heat and/or forced air, as is known in the art.

The method <NUM> can also include testing <NUM> the clean fibers after drying <NUM> for metal analysis and/or other contaminate analysis to ensure levels of components other than fibers are at desired levels.

Advantageously, the clean fibers from method <NUM> can be used to manufacture an article from recycled fibers. An article using recycled clean fibers from method <NUM> discussed herein can be manufactured in the same fashion as articles manufactured from original fibers via methods known in the art. The clean fibers from method <NUM> that are being recycled can form <NUM>% of the fibers of the article, or a lesser percentage of the fibers of the article.

Turning now to <FIG>, it can be seen that preferable levels of added magnetic particles <NUM> can enhance the efficacy and efficiency of the method <NUM>. <FIG> provides a representation of the accumulative attracted amount of contaminates, added magnetic particles, and fibers attracted to the magnet <NUM> as described above as removed from the magnet <NUM> when the magnet <NUM> was removed at intervals of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> minutes in the small scale testing that was conducted following method <NUM>, and as described above. For <FIG>, the magnetic particles were added <NUM> by being added directly to the wiper, also referred to as "spiked" on the wiper. In <FIG>, the added magnetic particles <NUM> were iron, iron oxide, and lead oxide, with the various concentrations being noted as "ppm" for each of those specific magnetic particles. For example, for the data represented by "<NUM> ppm," means the wipers were spiked with <NUM> ppm of iron, <NUM> ppm of iron oxide, and <NUM> ppm of lead oxide. <FIG> provides a similar representation of the accumulative attracted amount contaminates, added magnetic particles, and fibers versus time as <FIG> discussed above, except <FIG> displays the embodiment discussed above where the magnetic particles were added <NUM> to the solution prior to pulping <NUM> and not directly on to the wiper. In <FIG>, the added magnetic particles <NUM> were iron and iron oxide, with the concentrations being noted as "ppm" for each of those specific magnetic particles as discussed above with respect to <FIG>.

<FIG> illustrates that adding no magnetic particles ("<NUM> ppm"), attracted less than <NUM> gram of contaminates and fibers on the magnet <NUM>, and the "<NUM> ppm" trial attracted only about <NUM> grams. However, each trials of "<NUM> ppm" and "<NUM> ppm" of added magnetic particles <NUM> provided much more efficient removal of contaminates, added magnetic particles, and fibers attracted to the magnet <NUM>, with the "<NUM> ppm" trial removing <NUM> approximately <NUM> grams of contaminates, added magnetic particles, and fibers after the fifth time of applying the magnetic field <NUM> and removing <NUM> the contaminates, added magnetic particles, and fibers, for a total time of <NUM> minutes. After such time, the original solution including the dissociated pulped fibers were visually more clear. The polypropylene fibers (as well as the contaminates attracted to them) were largely separated from the pulp fibers in the suspension <NUM> by being attracted to the magnet <NUM>, just as the magnetic contaminates and the added magnetic particles <NUM> that attracted other contaminates such as oil and grease were attracted to the magnet <NUM>.

Table <NUM>, below, provides the various trials of "<NUM> ppm" - "<NUM> ppm" and the accumulative dry mass weights, including the accumulative mass removed by the magnet <NUM> after <NUM> minutes and the accumulative mass recovered from the suspension <NUM> by filtering <NUM> the remaining solution for the small scale testing conducted where the magnetic particles were added <NUM> directly to the wipers (see <FIG>). It was theorized that <NUM> grams of contaminates, added magnetic particles, and polypropylene fibers could be attracted to the magnet <NUM> and approximately <NUM> grams of pulp fibers could be recovered. As shown in Table <NUM>, the "<NUM> ppm trial," the total accumulation of <NUM> grams on the magnet <NUM> is about <NUM> grams less than the expected total weight of the contaminates of oil/grease, added magnetic particles, and the polypropylene fibers, with the weight difference being mostly due to some oil staying with the solution from the pulping. The "<NUM> ppm trial" was also relatively effective, providing an accumulative mass on the magnet <NUM> of <NUM> grams after <NUM> minutes.

Reviewing <FIG> provides similar conclusions as can be drawn from <FIG>. Particularly, it appears that the "<NUM> ppm" and "<NUM> ppm" trials of added magnetic particles <NUM> were effective at removing a substantial portion of the contaminates, added magnetic particles, and polypropylene fibers after <NUM> minutes.

<FIG> show the similarity in effectiveness of method <NUM> between the two different ways that the magnetic particles can be added <NUM> in method <NUM>. <FIG> illustrates the accumulative removal amount of contaminates, added magnetic particles, and fibers attracted to the magnet <NUM> versus time comparing a wiper in a solution with magnetic particles added to the solution and a wiper in a solution with magnetic particles added directly to the wiper for <NUM> ppm of magnetic particles of iron and iron oxide. <FIG> and <FIG> portray the same comparison, except for "<NUM> ppm" and "<NUM> ppm" trials, respectively, as discussed above. As seen from <FIG>, whether the magnetic particles are added <NUM> directly to the contaminated article(s) or to the solution in which the contaminated article(s) will be pulped <NUM>, the effectiveness of the method <NUM> is substantially the same. Thus, the way in which the magnetic particles can be added <NUM> in method <NUM> provides flexibility for method <NUM> without sacrificing the efficacy of the method <NUM>. For example, in some circumstances, adding the magnetic particles <NUM> may not be possible or practical directly to the wiper due to the wiper's performance considerations or potential manufacturing limitations. In such a circumstance, adding the magnetic particles <NUM> to the solution in which the wiper is pulped <NUM> can provide substantially similar effectiveness for method <NUM> as if the magnetic particles <NUM> were added directly on to the wiper.

The method <NUM> can be particularly efficient for cleaning non-woven articles that include hydrophobic fibers or filaments. As previously noted, method <NUM> can be utilized to clean the fibers or filaments from a non-woven article that includes hydrophobic fibers or filaments, such as polypropylene. If a contaminated article includes such hydrophobic fibers/filaments, the method <NUM> can essentially separate hydrophobic and hydrophilic fibers (e.g., the hydrophobic fibers can be attracted to the magnet <NUM> and the hydrophilic fibers remain in the solution), in addition to the advantage that the hydrophobic fibers or filaments can indirectly help to remove metal contaminates along with oil and/or grease. To demonstrate this efficiency, a comparison study was performed by testing method <NUM> for a wiper including only pulp fibers against a wiper including <NUM>% pulp fibers and <NUM>% polypropylene fibers. Each of the wipers had <NUM> ppm each of iron, iron oxide, and lead oxide added <NUM> directly to the wiper before pulping <NUM>, as discussed above.

In this comparison, a difference between the two suspensions <NUM> created by pulping <NUM> was noticed. The suspension <NUM> including the wiper including the hydrophobic fibers (polypropylene) had conglomerates of contaminates formed on fibers in the suspension <NUM>, whereas the suspension <NUM> from the pulp only wiper seemed to have the contaminates dispersed in the solution of water. As illustrated in <FIG>, the wiper with the hydrophobic fibers (polypropylene fibers) realized an advantage in the accumulated amount of contaminates, added magnetic particles, and fibers that were attracted to the magnet <NUM>. While it needs to be appreciated that the accumulated amount for the wiper including the polypropylene fibers includes the mass of polypropylene fibers themselves attracted to the magnet <NUM>, the difference between the accumulated amount in each sample is not solely due to such fibers, as there are only about <NUM> grams of polypropylene fibers in the wiper, yet after <NUM> minutes the wiper with the polypropylene had over <NUM> grams more accumulated mass on the magnet <NUM>. While the method <NUM> can be employed for any contaminated article, advantages may be realized for articles including hydrophobic fibers or filaments.

Method <NUM> can also be utilized for cleaning contaminated articles whether they were used for cleaning fresh oil, or used oil. Fresh oils and used oils can be different in terms of their viscosity as well as metal-related contaminate levels. For example, fresh oils can be more viscous and free from metal contaminates whereas used oils can be less viscous and may potentially include various metal contaminates. A comparison study was conducted to compare the effect of method <NUM> on wipers having used oil and wipers having fresh oil. The wipers each had a composition of <NUM>% pulp fibers and <NUM>% polypropylene fibers and had <NUM> ppm each of magnetic particles of iron, iron oxide, and lead oxide added <NUM> directly to the wiper. For the used oil wipers, a used oil/grease mixture was made that included about <NUM> grams of used motor oil and about <NUM> grams of Valvoline® Moly-Fortified Multi-Purpose Grease, for an approximate <NUM>/<NUM> ratio of oil/grease. The used motor oil was collected by a motor repair/oil change shop and was used as received. For the fresh oil wiper, a fresh oil/grease mixture was made that included above <NUM> grams of fresh motor oil, Chevron® Supreme SAE <NUM> motor oil and about <NUM> grams of Valvoline® Moly-Fortified Multi-Purpose Grease, for an approximate <NUM>/<NUM> ratio of oil/grease.

Each wiper was put through the method <NUM>, and <FIG> illustrates the accumulated amount of contaminates, added magnetic particles, and fibers attracted to the magnet <NUM> at time intervals of <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> minutes. Table <NUM> below also provides the total accumulated amount of contaminates, added magnetic particles, and fibers attracted to the magnet <NUM> after <NUM> minutes as well as the fibers recovered from the solution after pulping <NUM> and removing <NUM> the contaminates. If all the oil/grease mixture and all the polypropylene fibers were to be attracted to the magnet <NUM>, then it would be expected that the accumulated mass would be about <NUM> grams, and the recovered pulp fibers would be expected to be about <NUM> grams if no pulp fibers were attracted to the magnet <NUM> and removed <NUM>. As illustrated in <FIG> and in Table <NUM>, the wipers with the fresh oil mixture provided more accumulation of contaminates, added magnetic particles, and fibers attracted to the magnet <NUM> than the wipers with the used oil, but the wipers with the fresh oil led to lower pulp fiber recovery. Despite these differences, the comparison study showed that the method <NUM> can be utilized for contaminated articles that have either or both fresh and used oil.

Method <NUM> which relies on a magnetic approach of adding magnetic particles <NUM> and applying a magnetic field <NUM> to remove contaminates from a contaminate article(s) can have benefits as compared to other cleaning methodologies relying more so on chemical detergents. From a process quality control standpoint, the known amount of add-on of magnetically attractive particles can streamline the process with exact control parameters. Additionally, from a cleaning perspective, the magnetic removal of oil and grease can potentially simplify the recycling process and minimize the use of water and detergent. Additionally, the method <NUM> can allow for almost complete separation of polypropylene fibers (or other hydrophobic fibers) from pulp fibers that can provide recycling opportunities for polypropylene fibers (or other hydrophobic fibers) once cleaned from other contaminates. After the method <NUM> is complete, the added magnetic particles can be recovered and reused by burning off all organic components and then re-using the magnetic particles in the method <NUM> or for other purposes.

<FIG> provides an alternative method <NUM> for cleaning fibers from a contaminated article. Method <NUM> can include similarities from method <NUM> illustrated in <FIG> and discussed above, can include pre-pulping preparation <NUM>, adding magnetic particles <NUM>, pulping <NUM>, applying a magnetic field <NUM>, removing <NUM> contaminates, filtering <NUM> the dissociated pulped fibers, and rinsing <NUM> the dissociated pulped fibers.

The method <NUM> provides additional processes to help clean the dissociated pulped fibers if some contaminates still remain after pulping <NUM> and removing <NUM> some of the contaminates from the contaminated article(s). The method <NUM> can include washing <NUM> the dissociated pulped fibers of the contaminated article(s) to provide washed pulped fibers. After rinsing <NUM> the dissociated pulped fibers, the dissociated pulped fibers can be combined with a detergent and a solution to form a suspension. The suspension can be held within a container and the solution used during washing <NUM> can be water. For example, washing <NUM> can include combining the dissociated pulped fibers with a desired amount of detergent. In some implementations, the detergent can be moderated and applied in steps as described in the PCT patent application entitled "<NPL>, by assignee Kimberly-Clark, the entire contents are hereby incorporated by reference. Washing <NUM> can include mixing the suspension that includes the dissociated pulped fibers and the detergent in the solution, for example, mixing with a mechanical mixer at a speed to effectively swirl and agitate the suspension in the container. In one embodiment, mixing can be performed using an IKA <NUM>-<NUM> RPM variable speed mixer, although any equipment capable of adequately mixing the suspension can be used in the washing <NUM> of method <NUM>.

In a preferred embodiment, the solution added to the suspension for washing <NUM> can be heated, and more particularly, it is preferable to heat the solution to at least about <NUM>. Not to be bound by theory, but it is believed that heating the solution for washing <NUM> can help provide benefits to fibrous structure matrix of any dissociated pulped fibers that may still be entangled or woven, and can also increase the solubility as well as the dispensability of both organic and inorganic contaminates in the solution.

Sample detergents that can be used include detergents, surfactants, or surfactant combinations that are commonly used for oil and grease cleaning or in personal care hygiene and cleaning products. Such surfactant or surfactant combinations can be selected from any of the following exemplary surfactant families: anionic, cationic, carboxylic, zwitterionic, and non-ionic series of surfactants and their combinations. Specific examples include, but are not limited to tritons, sodium stearates, alkyl benzenesulfonates, lignin sulfonates, dipropylene glycol methyl ethers, and alcohol ethoyxlates.

Although the above mentioned surfactant types may all suitable for the washing <NUM> described herein, the cleaning efficacy and the amount used for reaching the said cleaning efficacy may vary based on the surfactant or detergent used. In some cases, cleaning temperature and cleaning time may also be different depending on the surfactant or detergent used. However, preferred surfactant systems that are suitable for the washing <NUM> described herein should be effective to handle heavy and sticky portions of oils and grease, which in some used wipers can be up to or even double the wiper's fiber weight (e.g., a <NUM> gram clean wiper may absorb/wipe up to <NUM>-<NUM> grams of oils/grease). The heavy and sticky portions of oils/grease often consist of high molecular weight hydrophobic polymers (e.g., polybutenes, silicones, polyurathanes, fluorocarbon polymers, etc.) that will require surfactants to have strong hydrophobic affinities to them. Accordingly, surfactant systems that have long hydrophobic side alkyl chains will generally perform better than others. One example of such surfactants include is a family of alcohol ethoxylates (AEs), in which a long side alkyl chain usually has <NUM> to <NUM> carbon atoms and also combined with some ethylene oxide units (<NUM> to <NUM>).

In one embodiment, a sample detergent that can be used in the washing <NUM> described herein is a mixture of alcohol ethoxylates (AEs) with C12-<NUM> alkyl side chains and di-propylene glycol methyl ether at about ratios ranges of <NUM>:<NUM> to <NUM>:<NUM> (or generally referred it to Surfactant Chemistry A or SC A). Di-propylene glycol methyl ether is an organic solvent, but is fully soluble in water so that it can help further for breaking down "heavy & sticky" portions of oils/grease.

In some embodiments, the method <NUM> can include applying a magnetic field to the suspension when washing <NUM> the dissociated pulped fibers. It is preferable to use a magnetic field strength during washing <NUM> of at least about <NUM> Gauss. The magnetic field can be created by at least one magnet (e.g., one or more bar type neodymium rare earth magnets). The magnet(s) used to provide the magnetic field during washing <NUM> are preferably placed in the container such that each of the magnets are at least partially submerged in the suspension. Preferably, the magnet(s) are disposed and held near the sides of the container, so as to avoid interference with the mixing of the suspension during washing <NUM>. It is contemplated that the magnetic field could also be generated by providing an electromagnetic field as an alternative to, or in addition to, one or more magnets <NUM>.

In some embodiments, when washing <NUM> the dissociated pulped fibers while applying a magnetic field to the suspension, contaminates can be further removed the suspension as part of the washing <NUM> of the dissociated pulped fibers. Additionally, some contaminates can begin to accumulate on the magnets due to the magnetic field being applied to the suspension when washing <NUM> the dissociated pulped fibers in the suspension. As discussed above with respect to method <NUM> and the applying of a magnetic field <NUM> to the dissociated pulped fibers, metal contaminates may be attracted to the magnets through their intrinsic magnetic properties, and the spunbond polypropylene fibers (or other hydrophobic fibers) can also be attracted to the magnets and attract oil/grease. As the contaminates accumulate on the magnet(s) (either directly to the magnet surface and/or indirectly via hydrophobic fibers that are attracted themselves to the magnets), the magnets can periodically be removed from the suspension and wiped to remove contaminates from the suspension.

Advantageously, applying a magnetic field while washing <NUM> the dissociated pulp fibers with detergent can remove a wide variety of contaminates from the suspension. As noted above, if the contaminates include metal or other particles having intrinsic magnetic properties, then the magnetic field being applied during washing <NUM> can attract not only such particles, but also hydrophobic fibers including contaminates. Therefore, even if the contaminated article(s) includes contaminates in which the substantial portion of contaminates do not include metal particles or particles having intrinsic magnetic properties (e.g., oil, grease, solvents, and lubricants), applying a magnetic field to the suspension during washing <NUM> can help to remove more contaminates than only using a detergent during washing <NUM>. In some circumstances, the contaminated article(s) can include contaminates devoid of metal particles or particles having intrinsic magnetic properties (e.g., oil, grease, solvents, and lubricants), yet applying a magnetic field to the suspension while washing <NUM> can help to remove more contaminates than using only a detergent during washing <NUM>.

The washing <NUM> of the dissociated pulped fibers can occur for a time period sufficient to wash the dissociated pulped fibers. In a preferred embodiment of method <NUM>, the magnetic field can be applied to the suspension the majority of the time period that the washing <NUM> occurs. The contaminated solution <NUM> and detergent from the suspension after washing <NUM> can be put through a filtering mechanism and transferred to a waste-water facility <NUM> for further processing to remove the washed pulped fibers from the suspension.

After washing <NUM> the dissociated pulped fibers to provide washed pulped fibers, the method <NUM> can preferably include rinsing <NUM> the washed pulped fibers to remove excess detergent used in the washing <NUM> of the dissociated pulped fibers discussed above. The rinsing <NUM> can also provide the benefit of removing any contaminates confined in the washed pulped fibers that were not transferred in the contaminated solution <NUM> to the waste-water facility <NUM>. As illustrated in <FIG>, the rinsing solution <NUM> can also be transferred to a waste-water facility <NUM> for further processing. In some embodiments, it may be preferable to perform the rinsing <NUM> several times.

In some embodiments, the method <NUM> can include treating <NUM> the washed pulped fibers with a pH adjustment solution to provide treated pulped fibers. Treating <NUM> the washed pulped fibers can occur after the washed pulped fibers are removed from the wash box used in rinsing <NUM> the washed pulped fibers if rinsing <NUM> occurred. Alternatively, the treating <NUM> can occur in the same wash box used in rinsing <NUM> the washed pulped fibers. Treating <NUM> the washed pulped fibers in a pH adjustment solution can further remove metal contaminates, especially homogeneous metal ions and pH sensitive metal oxides and other metal compounds that can become soluble in a pH adjustment solution.

In one embodiment, the pH adjustment solution can include a simple acid such as adding pre-made solutions of hydrochloric acid, sulfuric acid, and/or other pH adjustment agents such as uronium hydrogen sulfate, an acid-base adduct of urea and sulfuric acid. The uranium hydrogen sulfate can further enhance the removal of contaminates as it can also function as a chelation agent to metal ions. The chelation can bring more ions from pulped fibers to water solutions so that they can be removed from fibers. In another aspect, it can be expected that residual uronium hydrogen sulfate left in recycled fibers may have some antimicrobial activity, which may be beneficial to recycling pulp fibers as mold growth can be prohibited.

Treating <NUM> the washed pulped fibers with a pH adjustment solution to provide treated pulped fibers can be include adding the washed pulped fibers to a pH adjustment solution created by mixing twelve liters of water and adjusting the pH to about <NUM> to about <NUM> by adding a solution including uranium hydrogen sulfate. The pH adjustment solution can be heated (preferably to at least about <NUM>), and in the small scale testing conducted, was heated to about <NUM> to about <NUM>. The washed pulped fibers can mixed for approximately thirty minutes with the aid of a variable RPM Lightening Mixer. The used pH adjustment solution <NUM> can be put through a filtering mechanism and directed to a waste-water treatment facility <NUM> for further processing.

If the method <NUM> includes treating <NUM> the washed pulped fibers with a pH adjustment solution, the method <NUM> can also preferably include rinsing <NUM> the treated pulped fibers. Similar to the discussion above regarding rinsing <NUM> the washed pulped fibers after washing <NUM>, rinsing <NUM> the treated pulped fibers can occur in a wash box with the assistance of a vacuum. The rinsed solution <NUM> from rinsing the treated pulped fibers can be directed to a waste-water treatment facility <NUM> for further processing.

Claim 1:
A method for cleaning fibers from a contaminated article, the method comprising:
providing a contaminated article comprising contaminates and at least one of fibers and filaments, wherein the contaminated article is a non-woven article comprising pulp fibers and at least one of polymeric fibers and polymeric filaments, and wherein the contaminates are selected from the group consisting of oils, greases, solvents, and lubricants;
adding a plurality of magnetic particles to a first solution;
pulping the contaminated article to separate the at least one of fibers and filaments from the contaminated article to provide dissociated pulped fibers, wherein pulping the contaminated article to separate the at least one of fibers and filaments from the contaminated article to provide dissociated pulped fibers occurs in the first solution after the plurality of magnetic particles are added to the first solution;
applying a magnetic field to the suspension including the dissociated pulped fibers;
removing at least some of the plurality of magnetic particles and at least some of the contaminates from the suspension; and
drying the dissociated pulped fibers to provide clean fibers.