US 20040010841 A1
A protective garment for capture and filtration of flatus wherein the garment comprises a water vapor-permeable, air-impermeable membrane that provides a containment body. The containment body captures flatus but not moisture, and a chemically active filter disposed over a hole in the containment body remove odor from the flatus. In one embodiment, the membrane is impregnated with a chemically active substance that also acts as a filter. In another embodiment, the membrane is laminated to a stretchable fabric to increase mechanical efficiency as well as comfort.
1. A protective garment that removes odiferous components of flatus, the underwear comprising a containment body that comprises a water-vapor-permeable, air-impermeable membrane, the garment being constructed so as to seal elastically around the wearer's lower torso and upper thighs, the garment also being provided with a hole in the containment body and a substantially flat, chemically active filter disposed over and the hole, at least one broad side of the filter having a greater surface area that the area of the hole.
2. The garment of claim one wherein the containment body comprises the membrane of claim one laminated to a stretchable, air-permeable fabric, the lamination being disposed to allow the combined membrane and fabric to be stretchable;
3. The underwear described in claim one wherein the membrane is impregnated with at least one chemically active substance that removes odors.
 The invention relates to an undergarment. More specifically, it relates to a protective undergarment with filtration properties to remove the malodorous components of flatus.
 THIS APPLICATION IS RELATED TO A PROVISIONAL PATENT APPLICATION FILED JUN. 25, 2001 BY STEPHEN P GILMARTIN.
 The invention improves upon U.S. Pat. No. 5,593,398 (the “Weimer patent”), which discloses protective underwear with a flatus filter (the “Weimer device”). The purpose of the Weimer device is to capture the flatus of the wearer and remove the odor from that flatus by forcing it to escape, if at all, through a chemically active filter. The device thus saves the wearer from embarrassment or opprobrium.
 The Weimer device, however, leads to other problems related to the buildup of moisture. Since water vapor cannot escape through the containment body of the Weimer Device, moisture accumulates inside the pants. The Weimer device does not effectively address moisture buildup because the Weimer patent provides and claims a system which traps water vapor as well as flatus. The Weimer patent describes “bifurcated underwear” which must be “primarily made of vinyl-coated nylon” (col. 2, In. 4; col 4, In. 51 (Claim 1a)), or of “air-tight polyeruthane-coated nylon” (Abstract, line 1), or of “air-tight vinyl-coated nylon” (col. 3, Ins. 50-51), or of “any nonporous material that will allow the flatus to remain inside and eventually [be forced] out through the exit hole” (col 2, Ins 59-60; see col. 2, In, 62). The Weimer patent acknowledges that such impermeable materials could cause a build up of sweat inside the underwear, which would cause discomfort and other problems. To alleviate the problems, the Weimer patent proposes “a polyester or cotton lining in case of sweating” (col. 22, In. 63), or in other words, “a soft cotton or polyester knit inner lining for maintaining dry skin” (col. 4, Ins. 26-27). The Weimer patent also suggests “enlargement” of the filter and exit hole to “help prevent the build-up of moisture” (col. 4, In. 36).
 Better methods of addressing the moisture problem are desirable. As an initial matter, since warm, moist environments are ideal breeding grounds for odor-causing organisms, the build up of moisture inside the underwear can be counterproductive to the main purpose of such protective underwear: control of embarrassing odors. Other unhealthful organisms, such as molds, fungi and bacteria that cause skin conditions, can also proliferate in such an environment, causing health and hygiene problems.
 In addition, the knit lining proposed in the Weimer patent would quickly become saturated with sweat. Increased activity, warm weather, stress, obesity, and the like only exacerbate this moisture build-up problem.
 Further, whereas the only solution offered in the Weimer patent is an enlarged vent and filter, the filter cannot be enlarged indefinitely to mitigate the moisture problem without rendering the underwear itself, not just the moistness, uncomfortable. The enlarged filter can only occupy areas where it does not impede movement, chafe, or otherwise cause discomfort to the wearer. Areas distant from the filter would thus remain subject to moisture collection.
 Further still, because the Weimer device relies on an absorptive lining and access to the filter to control moisture buildup, the Weimer device cannot use an elastic outer layer, such as ordinary, nylon pantyhose, to force the underwear to conform to the skin. Provision of an elastic an outer layer or elastic overgarment in the Weimer device would impede water vapor migration, retarding the moisture's escape though the filter and thus hastening the saturation process and leading more quickly to discomfort and potentially increased odor or health and hygiene difficulties. Provision of an elastic outer layer or overgarment is desirable because it would cause the underwear to conform to the skin, thereby forcing the flatus out the filter sooner, reducing the likelihood of leakage. Form fitting underwear also provides greater comfort for the wearer if the wearer engages in activities that involve a lot of movement, such as sports, especially for males.
 The impermeable nature of the underwear disclosed in the Weimer patent can thus compound the problem the Weimer device is designed to solve and cause new problems as well. it also prevents addition of comfort features such as overall elasticity and use of form fitting fabrics.
 By providing a porous, breathable membrane instead of air-tight, water-trapping fabric for the underwear, the invention addresses the moisture problem without unduly sacrificing the efficiency of filtration of flatus. In fact, the invention improves the efficiency of the filtration process by allowing for use of elastic outer layers or overgarments, while simultaneously increasing comport.
 The invention is underwear with a flatus filter like the Weimer device, but wherein the underwear are comprised of or lined with a porous membrane that allows water vapor to escape but that nevertheless offers sufficient resistance to the diffusion of flatus that the flatus is filtered and released through the vent. Accordingly, there are several objects of the invention, including:
 a) to provide a device for filtration of flatus that does not compound the problem of odors;
 b) to provide a device for filtration of flatus that does not cause hygienic problems related to the presence of warmth, moisture, and bacteria, fungus, mold, and the like.
 c) to provide a device for filtration of flatus that is substantially more comfortable to the wearer than moisture-trapping devices of the prior art.
 d) to provide a device for filtration of flatus that is substantially more comfortable than the inelastic devices of the prior art.
 Advantages of the invention are increased comfort for the wearer, reduced odor upon removal of the device by the wearer, and reduced hygienic problems.
 The above described concepts and other aspects of the invention are described with reference to the drawings of the preferred embodiment. The illustrated embodiments are intended to illustrate, not to limit, the invention. The drawings contain the following figures:
FIG. 1 depicts a perspective, magnified, cut-away view of human skin and a wall of ordinary, porous, fabric underwear fitted with a filter like that of the Weimer device, showing that flatus is trapped and forced through a filter, but that water vapor is also trapped.
FIG. 2 depicts a perspective, magnified, cut-away view of human skin, a wall of the air-impermeable underwear of the Weimer device, and a filter, showing that the flatus is forced through the filter but that water vapor is trapped and condenses as moisture. Features such as water vapor, flatus, sweat glands, the filter, and the exit vent depicted in FIG. 1 are also depicted in FIG. 2.
FIG. 3 depicts a perspective, magnified, cut away view of human skin and the air-impermeable, water vapor-permeable membrane and filter of the invention, showing that water vapor can escape through the membrane while flatus is trapped and forced through the filter. Features such as water vapor, flatus, sweat glands, the filter, and the exit vent depicted in FIG. 1 are also depicted in FIG. 3.
FIG. 4 shows a perspective view of an embodiment of the protective underwear of the invention, including containment body made of the material of the invention, as well as a waistband, thigh cuffs, exit hole, filter, and pocket to contain the filter situated over the exit hole.
 As shown in FIG. 1, human skin contains two different kinds of sweat glands: eccrine sweat glands, which excrete sweat through pores on the surface of the skin, and, appocrine sweat glands, which are connected to the ducts through which hair reaches the surface of the skin. FIG. 1 shows that ordinary, porous fabric such as cotton offers little resistance to the diffusion of gas. As a result, FIG. 1 shows, both flatus and water vapor from the sweat glands escape readily through the walls of the underwear itself. Flatus is not trapped and forced out through the filter. Odor is not controlled.
FIG. 2 shows that the barrier in the Weimer device traps both flatus and water vapor. The water vapor therefore collects in liquid form inside the underwear, causing discomfort and providing an environment for odor causing and unhealthful organisms to grow.
 The invention is similar in construction to that described in the Weimer patent (U.S. Pat. No. 5,593,398). Instead of the non-porous, air-tight, vinyl-coated underwear the Weimer patent claims, however, the invention provides a porous, water-vapor-permeable membrane to contain the wearer's flatus, but not the wearer's sweat. That membrane can be made of expanded polytetrafloraethylene (“ePTFE”). The ePTFE can also be laminated to a stretchable fabric, thereby allowing for elastic, form-fitting underwear that not only improves comfort and mobility for the wearer, but also helps to force the flatus out through the filter sooner, thereby reducing the likelihood of the flatus escaping by other paths that would not control the embarrassing odor. The membrane can also be impregnated with chemically active particles such as carbon, so that the membrane itself acts as a filter.
 Turning to FIG. 4, in the prior art such as the Weimer patent, a containment body 2 is comprised of non-breathable, or water-vapor impermeable, fabric. Together, an elastic waist band 1, containment body 2, and leg cuffs 3 trap flatus inside an airtight chamber. Therefore, the flatus and water vapor trapped in the containment body must escape, if at all, through the filter 4 and out through the vent hole 5. The filter 4 provides the path of least resistance for diffusion of the flatus and water vapor because it provides effectively the only path in the Weimer device for such diffusion of both substances.
 In the invention, in contrast, the containment body 2 comprises a breathable membrane that offers sufficient, short-term resistance to the diffusion of gas that the filter remains the path of least resistance for the flatus, but the membrane also permits water vapor trapped in areas distant from the filter to escape through the membrane itself. Thus, the invention allows conditions inside the underwear to stay drier. If the membrane is laminated to, or enclosed within, a form fitting, elastic outer layer, such as knitted nylon, then the flatus is forced through the filter sooner because it lacks alternative paths that have less resistance. Thus, a stretchable outer layer improves mechanical efficiency. In addition, the membrane itself can be impregnated with chemically active charcoal or other substances, so that even if flatus escapes through the membrane, it is filtered.
 Artisans with ordinary skill in producing ePTFE and garments lined with ePTFE can produce underwear that comprise the breathable layer of the invention in place of the impermeable layer of the Weimer device. While any air-impermeable material with appropriate moisture vapor transmission rate (not lower than approximately 500 grams/sq. meter/day) is suitable for the underwear, a hydrophobic and hydrophilic composite such as that described in U.S. Pat. No. 4,194,041 is preferable. Alternatively, such a material that is impregnated with a chemically active filtering substance, such as charcoal, is appropriate. Methods of impregnating ePTFE membranes with particles of carbon (charcoal) are known in the art. See, e.g., U.S. Pat. No. 5,524,908. To reduce leakage of unfiltered flatus, the material should be capable of being seam sealed. Methods of constructing ePTFE garments with sealed seams that form a sealed barrier between the wearer and the outside environment are well known in the art. Seams may be sewn with a PTFE monofilament first, then sealed. For example, U.S. Pat. No. 4,283,448, “Composite Polytetrafluoroethylene Article And A Process For Making The Same,” describes a process for making a “porous” ePTFE “article which is made up of a number of smaller articles . . . joined to one another such that their microstructure is virtually unaltered across the join.” That process involves “closely abutting small-shaped PTFE segments and applying a force perpendicular to the seam while heating to a temperature above the crystalline melt point of the segments.” See also, e.g., U.S. Pat. No. 4,932,078 (ePTFE-lined clean-room suit).
 More specifically, methods of making short, close fitting pants out of water-vapor-permeable, air-impermeable material, like the underwear of the invention, are known in the art. In fact, U.S. Pat. No. 5,334,174, describes a preferred method of making the underwear in the present invention except that the invention does not require the provisions for hoses. Likewise, U.S. Pat. No. 5,804,011 describes a suitable process for making the material of which the preferred embodiment is comprised.
 In the preferred embodiment, the breathable material, such as GORE-TEX® ePTFE, is laminated to a stretchable fabric, such as LYCRA® knitted nylon. GORE-TEX® ePTFE is commercially available from W. L. Gore & Associates, Inc. LYCRA® fabric is commercially available from E. I. DuPont & de Nemours, Inc. The stretchable fabric disclosed in U.S. Pat. No. 4,443,511 is acceptable, too. U.S. Pat. No. 5,660,918 describes a suitable, wash durable method for producing a stretchable material laminated to an ePTFE membrane. Given the purpose of the invention, washability is crucial.
 Using such known methods of the prior art, those skilled in the art can create underwear comprising a water-vapor-permeable, air-impermeable containment body provided with a vent hole, with a filter, a pocket situated over the vent hole to contain the filter. It is also a known how to make such underwear of a stretchable fabric or with an appropriately stretchable waistband and thigh cuffs. Finally, it is known how to make that containment body out of a water-vapor-permeable, air-impermeable material that is impregnated with chemically active particles such that the material itself acts as a filter.