Composite undergarment fabric

Abstract: A composite textile fabric for moving moisture away from the skin is provided. The composite fabric includes a first fabric layer comprising either a polyester, acrylic or nylon material which has been rendered hydrophilic, a second fabric layer comprising at least 5% by weight of a super absorbent material and a barrier layer having a high moisture vapor transmission rate applied to said second fabric layer. The first fabric layer and the second fabric layer are formed integrally and concurrently by knitting a plaited construction.

Description: Background of the Invention This invention relates to a composite undergarment textile fabric, and more particularly to a composite fabric comprising a hydrophilic polyester, acrylic or nylon layer, and an absorbent layer made of cotton, rayon, a super absorbent material or a blend thereof, with a breathable barrier layer applied thereto. Together, these layers act to move urine or other body fluids away from the skin and through an undergarment made with the composite fabric. A significant problem for many elderly individuals is their inability to control urination, generally known as incontinence. Though many individuals with this problem are forced to wear an adult-size diaper, this can often be both degrading and because of its bulk, very uncomfortable. In addition, most adult sized diapers are not reusable. It would therefore be desirable to have an undergarment made of a material that looks, feels and can be laundered like conventional underwear, but which readily retains and transports urine away from the skin of the wearer. Most conventional undergarment textile fabrics are likely to result in the substantial enclosure of urine between the wearer's skin and the undergarment. When saturation of the undergarment takes place, accumulated urine wets the body of the garment wearer such that he begins to feel uncomfortable. Adult size diaper materials besides being bulky and uncomfortable, cannot be laundered or reused. Where a super absorbent material is used, that material is usually in the form of a powder. While commercially available super absorbent powders offer a range of water-absorbent characteristics, they can be difficult to incorporate into absorbent products. Furthermore, there is a tendency for them to migrate from their location. Special equipment is often required to handle them and they must be kept in place by gluing, fusing or lamination to a support structure. Also, the gels formed from powders and water have little integrity and are, therefore, difficult to contain within a structure when subject to pressure. Accordingly, it would be desirable to provide a textile fabric which overcomes the above disadvantages, and which helps transport moisture such as urine away from the skin of the wearer. FR-A-2570935 believed to be the closest prior art describes a knitted two-layer fabric with improved absorbtion of sweat and comprising a first fabric layer made of hydrophobic synthetic fibers and a second, moisture-absorbing, fabric layer. The fabric is intended particularly for use in sportswear. The present invention provides a composite textile fabric for moving urine or other body fluids away from the skin and retaining it. The present invention is related to a composite fabric comprising a first fabric layer of synthetic yarn and a second fabric layer made of moisture absorbing yarn, the first and second fabric layer being formed integrally and concurrently by knitting a plaited construction, the composite textile fabric being characterised in that said synthetic yarn of the first layer is selected from polyester, acrylic and nylon and either is hydrophilic or has been rendered hydrophilic, said yarn of the second fabric layer comprises at least 5% by weight of super absorbent fiber and/or said second fabric is chemically modified to render it super absorbent and said composite textile fabric further includes a breathable barrier layer applied to the second fabric layer. The first fabric layer and the second fabric layer are formed integrally and concurrently by knitting a plaited construction so that the layers are distinct and separate yet integrated one with the other, e.g. as illustrated in Figure 1 which illustrates a terry construction, which is a preferred construction. The invention also provides a method of forming the fabric comprising forming a knitted plaited construction comprising said first fabric layer and said second fabric layer and depositing a breathable barrier layer on said second layer. The barrier layer provides a gating mechanism for promoting transport of urine from the first fabric layer as the water contained therein evaporates from the second fabric layer and through the barrier layer. The advantage of providing a breathable barrier layer is that the weight of liquid retained by the absorbent layer is slowly and continually reduced by evaporation without allowing liquid through the barrier layer to wet the outer garments of the wearer. The barrier layer may be monolithic and hydrophilic or microporous and hydrophobic or a combination thereof. The first fabric layer is made from a polyester, acrylic or nylon material and is worn against the skin. Because the polyester, acrylic or nylon material of the first fabric layer is, or is treated to be, hydrophilic, urine from the skin is quickly transported through the first layer and is then absorbed by the second layer of the composite fabric. Water contained in the urine absorbed in the second fabric layer is then evaporated from the surface of the second layer and the water vapor is selectively transported through the barrier layer to the outside of the garment (the surface of the barrier layer). Of significance is the fact that the fabric construction is plaited. This feature helps to create a substantial moisture concentration gradient between the surface of the polyester, acrylic or nylon layer (which transports urine from the skin), the absorbent layer (which absorbs the urine from the first layer), and the barrier layer (through which the water contained in the urine is evaporated). Also of importance is the fact that a breathable barrier layer is deposed on the absorbent layer. Because the barrier layer has a high moisture vapor transmission rate, moisture retained by the absorbent layer evaporates without wetting the outer garment of the wearer. Thus, the invention provides an improved composite textile fabric for enhancing the transport of body fluids, for example urine, away from the skin. The use of plaited layers promotes the moisture concentration gradient between the layers. An undergarment formed from the textile fabric of the invention has the drapeability and feel of conventional undergarments and can be laundered and reused in a conventional manner. A further advantage of the composite textile fabric is that it retains absorbed urine even when compressed. The invention is now described in greater detail with reference to preferred embodiments. The first fabric layer is made from a polyester, acrylic or nylon material and preferably comprises between about 20% and 75% by weight of the composite fabric. The second fabric layer preferably comprises between about 20 and 75% by weight of the composite fabric. The preferred material for the first fabric layer is polyester. The amount of each fabric layer is selected based on the desired weight of the composite fabric, the end use desired of the composite fabric and the requirements for transferring urine from the polyester, acrylic or nylon layer to the moisture absorbent layer, and from the moisture absorbent layer through the breathable barrier layer. The weight per unit area of the composite fabric is preferably between about 101.7 and 339 g/m 2 (3 ounces/yards 2 and 10 ounces/yard 2 ), depending upon the end use requirements for wetness control. In accordance with the invention, the construction of the composite fabric is such that it is plaited -- although each fabric layer is distinct and separate, each is integrated with the other. As a result, the composite fabric functions as a single unit. The composite fabric may be constructed as a warp or weft knit, such as a plaited jersey, interlock, plaited interlock, two-end fleece, three-end fleece, terry with regular plaiting, double terry, double needle raschel and tricot. The selection of fabric construction will be based on the need for certain end-use requirements such as thermal insulation, distancing the absorbent layer further away from the wearer's skin, or providing the thinnest possible underwear fabric. Where a raised surface fabric is desired, the terry or fleece construction, followed by surface finishing, would be selected. The second layer, as stated above, must in one embodiment include in the yarn at least 5% by weight of a super absorbent fiber. Preferably, the second layer should include at least 25% by weight of a super absorbent fiber. The preferred moisture absorbent materials comprise a blend of cotton and or rayon and a super absorbent fiber such as a copolymer of acrylic acid, the latter being partially neutralized. The use of a super absorbent fiber is desirable in that the fibers will absorb many times their own weight, even when under pressure and they will retain the absorbed liquid when subjected to pressure. They swell many times as they absorb fluids and they do it faster than powder due to the small diameter of the fibers, approximately 30 microns, which gives a very high surface area for contact with the liquid. Other benefits of fibers also derive from their physical form. Because they are long compared to their diameters (length to diameter ratio at least 100), they become entwined in a structure and are less liable to migrate through agitation. The fabrics containing fibers are flexible and soft even when high levels are added. These types off fibers are produced by: Toyobo Co. Ltd., Osaka, Japan; by Allied Colloids Limited, Bradford, England; and by Courtaulds Fibers Ltd., Coventry, England. The preferred fiber is Lanseal F, produced by Toyobo Co. Ltd. Test results reveal that such fiber retains 40 to 60 times its weight in urine. Alternatively, the second layer may be knit with a yarn that is comprised of cotton or rayon. If the second layer is knit with a yarn that is comprised of cotton or rayon, the second layer, itself, may be chemically modified after knitting the composite fabric by treatment with alkyl chlorides and cross linking of the resultant ethers to form carboxyl methylated cellulosic fibers, as is known to one of skill in the art, to render the layer super absorbent . In a preferred embodiment, the second fabric layer includes cotton and super-absorbent fibers as the major constituents. A breathable barrier layer is deposited on the second fabric layer. The barrier layer may be deposited by transfer coating from "release" paper. It may also be deposited by conventional film or membrane lamination techniques. The barrier layer is made of either a microporous hydrophobic material or a non-porous hydrophilic material, or a mixture (blend) thereof. The polyester, acrylic or nylon of the first layer is preferably either round or modified cross-section, 0.3 to 6.0 denier, and either spun or filament. The layer is chemically modified or utilizes a modified fiber so that it is rendered hydrophilic, as described herein-below. After constructing the composite fabric of the invention, the fabric may also be dyed as disclosed in EP-A-0515206. Also, an anti-microbial may be added to retard the growth of odor causing bacteria. In order to render the polyester, acrylic or nylon layer hydrophilic, a low molecular weight polyester is added. Examples of suitable low molecular weight polyesters are Milease T manufactured by I.C.I., Scotchrelease FC-226 manufactured by the 3-M Company of Minneapolis, Minnesota, Zelcon manufactured by DuPont of Wilmington, Delaware, and Avconav S.R. manufactured by AVCO of Tel Aviv, Israel. The amount of the low molecular weight polyester added is preferably between about 1.75 and 2.75 weight percent based on the weight of the composite fabric. The most preferred amount is 2.25 weight percent based on the weight of the composite fabric. One can also purchase polyester, acrylic or nylon yarn which is already hydrophilic. The surface of the yarn may be treated chemically during the spinning process. Alternatively, in manufacturing the yarn fibers, hydrophilic blocks such as polyethylene glycol are added during the polymerization process. Examples include a chemically modified nylon such as Hydrofil, a Nylon 6 copolymer manufactured by Allied Signal Inc. of Petersburg, Virginia; Thermastat, a modified polyester manufactured by DuPont of Wilmington, Delaware; and Dunova, a modified acrylic manufactured by Bayer of Leverkusen, Germany. By using a chemically modified fiber or by chemically modifying the first fabric layer, the layer is rendered substantially hydrophilic. As a result, the transport of urine from the surface of the first fabric layer to the moisture absorbent layer is substantially enhanced. Particularly, urine is made readily transportable along the surface of each polyester, acrylic or nylon fiber. A significant aspect of the inventive composite fabric is the deposition of a breathable barrier layer on the absorbent layer. The barrier layer preferably comprises between about 3 and 20% by weight of the fabric. The barrier layer may be adhered to the second layer by conventional membrane-film lamination or transfer coating technology. The barrier layer may be non-porous and hydrophilic or microporous and hydrophobic, prevents the wearer's outer garment from getting wet, and has a high moisture vapor transmission rate which enables the water contained in the urine retained by the second layer to evaporate and be transported away from the undergarment without wetting the outer garment of the wearer. A second significant aspect of the inventive composite fabric is that there is nothing interposed between the first fabric layer and the urine absorbent layer. The two layers are formed integrally and concurrently by knitting a plaited construction so that the layers are distinct and separate yet integrated one to the other. Together the layers act to move urine away from the skin and through an undergarment made with the composite fabric by the creation of a moisture concentration gradient. Evaporation into the exposed air from the second layer and through the barrier layer sets up the gradient which serves as the driving force to move or transport the moisture through the fabric. In particular, urine is "transported" quickly through the first layer, and then absorbed by the second layer. In other words, the first layer acts as a buffer between the skin and the second layer, and as a result, the skin is maintained in a dry condition. The water contained in the urine is then evaporated and the vapor is transported through either the micropores of the hydrophobic barrier layer or the non-porous hydrophilic barrier layer. A suitable microporous hydrophobic material is UCE 2000 manufactured by UCB Chemical Corp. of Drogenbos, Belgium; a suitable hydrophilic material is PORELLE manufactured by Provair of the United Kingdom. For a more detailed discussion of suitable breathable barrier layer materials and their function, reference is made to US-A-5204156. Optionally, another fabric layer may be laminated to the exposed portion of the barrier layer. This fabric layer may be jersey or a raised surface fabric. The underwear textile fabric of the invention is drapeable with good stretch and recovery and can be cut and sewn to standard underwear sizes. It is similar in appearance to, and can be laundered as, normal underwear, but has absorbent properties similar to, and enhanced liquid retention properties compared with, those of bulky disposable diapers. Although the fabric of this invention is preferably used as an underwear textile fabric, it may also be used for other purposes such as a bed pad for hospital or nursing facility. Lanseal, Milease, Scotchrelease, Zelcon, Avconav, Hydrofil, Dunova, Thermostat, UCE 2000, PORELLE are all trade marks which may be registered in one or more of the designated territories.

Claims: A composite textile fabric comprising a first fabric layer of synthetic yarn and a second fabric layer made of moisture absorbing yarn, said first and second fabric layers are formed integrally and concurrently by knitting a plaited construction, the composite textile fabric being characterised in that said synthetic yarn of the first layer is selected from polyester, acrylic and nylon and either is hydrophilic or has been rendered hydrophilic, said yarn of the second fabric layer comprises at least 5% by weight of super absorbent fiber and/or said second fabric is chemically modified to render it super absorbent, and said composite textile fabric further includes a breathable barrier layer applied to the second fabric layer. A fabric as claimed in claim 1 characterised in that said second fabric layer comprises at least 25% by weight of a super absorbent fiber. A fabric as claimed in claim 1 or claim 2 characterised in that the second fabric layer comprises moisture absorbent materials selected from cotton, rayon and super absorbent fibers. A fabric as claimed in claim 3 characterised in that said moisture absorbent material comprises a yarn blend of super absorbent fibers and at least one of cotton fibers and rayon fibers. A fabric as claimed in any one of claims 1 to 4 characterised in that said super absorbent material is a copolymer of partially neutralized acrylic acid. A fabric as claimed in any one of claims 1 to 5 characterised in that said fabric has a warp or weft knit construction selected from plaited jersey, interlock, plaited interlock, two-end fleece, three-end fleece, terry with regular plaiting, double terry, double needle raschel and tricot. A fabric as claimed in any one of claims 1 to 6 characterised in that the first fabric layer comprises between about 20% and 75% by weight of the fabric and said second fabric layer comprises between about 20 and 75% by weight of the fabric. A fabric as claimed in any one of claims 1 to 7 characterised in that said fabric has a weight per unit area of between about 101.7 and 339g/m 2 (about 3 ounces/yard 2 and 10 ounces/yard 2 ). A fabric as claimed in any one of claims 1 to 8 characterised in that said first fabric layer material is rendered hydrophilic by one or more of the following: inclusion of a low molecular weight polyester in an amount between about 1.75 and 2.75 weight percent based on the weight of the composite fabric; making the fabric layer from a yarn that is rendered hydrophilic by chemically treating the surface thereof; making the fabric layer from a yarn which is rendered hydrophilic by adding hydrophilic blocks during polymerization. A fabric as claimed in any one of claims 1 to 9 characterised in that the barrier layer is selected from a microporous hydrophobic material, a monolithic hydrophilic material or a blend thereof. A fabric as claimed in any one of claims 1 to 10 characterised in that the barrier layer comprises between about 3 and 20 weight percent of the fabric. A fabric as claimed in any one of claims 1 to 11 characterised in that said material of said first fabric layer is polyester. A method of constructing a composite textile fabric containing a first fabric layer of synthetic yarn and a second fabric layer made of moisture absorbing yarn wherein said first and second fabric layers are formed integrally and concurrently by forming a knitted plaited construction comprising said first layer and said second layer characterised in that the synthetic yarn of said first layer is selected from polyester, acrylic and nylon and either is hydrophilic or has been rendered hydrophilic, said moisture absorbing yarn of the second fabric layer comprises at least 5% by weight of super absorbent fiber and/or said second fabric is chemically modified to render it super absorbent, and the method further includes depositing a breathable barrier layer on the second layer. A method as claimed in claim 13 characterised in that said barrier layer is applied to said second fabric layer by conventional film or membrane lamination techniques or by transfer coating. A method as claimed in claim 13 or claim 14 characterised in that the material of said first fabric layer is selected from acrylic, polyester and nylon which has been rendered hydrophilic and said second fabric layer comprises at least 5% by weight of super absorbent fiber. A method as claimed in claim 13 or claim 14 characterised in that the first fabric layer is rendered hydrophilic after the knitting step. A method as claimed in claim 13 or claim 14 characterised in that the material of said first fabric layer is selected from acrylic, polyester and nylon which is rendered hydrophilic, said second fabric layer contains moisture absorbent fibers and said second fabric layer is chemically modified to render the moisture absorbent fibers super absorbent. A method as claimed in claim 17, characterised in that said modifying step comprises treating the moisture absorbent fibers with alkyl chlorides and cross linking the resultant ethers to form carboxyl methylated cellulosic fibers.

Inventors: LUMB DOUGLAS, ROCK MOSHE, LUMB, DOUGLAS, ROCK, MOSHE
Applicants: MALDEN MILLS IND INC, MALDEN MILLS INDUSTRIES, INC.
Application year: 1993
Main classification: A61F13
IPC codes: D06M17, A61F5, A61F13, A41D31, B32B5, D04B1