US 3427670 A
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Description (OCR text may contain errors)
Feb i8, i969 M. NIMOY 3,427,670
UNDERPAD Filed June 22, 196'? Sheet of 2 Tll. (PRO ART) l INVENTOR. MYV/N /V/Mo Y.
BY M l k ATTO NEY M. NIMOY UNDERPAD Feb. 18, i969 Filed June 22, 1967 INVENTOR //'/f y//v /V//wo Y NEON United States Patent O 1 Claim ABSTRACT F THE DISCLOSURE This invention is with respect to a launderableunderpad having a water repellent layer where fabric bunching due to differential in shrinkage between fabric layers and the entrapment of internal pilling in such pad have been obviated.
Underpads are designed, in the main, to function to protect the bed, i.e. blankets, sheets and mattress, from soiling due to body exudates, e.g. urine. Many materials have been utilized for this purpose, however, while the need for a pad that can be laundered and reused over a long duration is established, several disadvantages have appeared which have severely hampered the use of such an item to date.
These and other disadvantages are overcome by the instant invention which provides a launderable underpad comprising a plurality of plies of ydiaper fabric superimposed in facewise engagement and a sheet of flexible water impervious material secured in facewise engagement to at least one ply of said fabric, said fabric being present in sufficient excess to satisfy the shrinkage differential between said water impervious sheet, and said underpad having spec-ifically located openings for the removal of fiber pills.
The water impervious repellent layer of the launderable underpad of this invention must be flexible and must remain flexible through repeated laundering and drying. It must not stiften and crack to provide liquid strike through areas and it must not provide the discomfort factor that is defined by a stiffened or stiff layer or ply in the underpad.
The repellent ply or layer of this invention comprises a layer of flexible water impervious material which does not lose the major portion of its flexibility after undergoing repeated laundering and drying cycles and a layer of textile backing material secured to this water impervious material. The water impervious material must be resistant to attack by laundry soaps, detergents, bleaches and other such materials or chemicals used in the normalwashing or laundering of such pads. It must be nonirritating to the skin of the average person under reasonable conditions and it must not present a disagreeable odor.
Since normal laundering takes place in the presence of water heated to a temperature range between about 170 F. and about 200 F., and normal drying takes place at temperatures ranging up to about 350 F., the water impervious repellent layer must retain the major portion of its flex life through at least about one hundred each of the laundering and -drying cycles as defined herein.
Preferably the material used in, or for, this repellent layer is butyl rubber since it easily satisfies all of the above requirements, although acrylic polymers and silicone rubbers and other such materials can also be utilized. Also, the repellent layer may consist, in total, of a sheet of the above defined materials, however, present day plastics do not combine desirable hand and strength. For example, if any of the present day plastics are made into sheet form thin enough to use, they will be too weak to withstand tearing, while if they are thickened to provide sufficient tear strength, flexibility and hand are often ice sacrificed and the economics involved become prohibitive. Additionally, washing and drying machines are loaded on a weight basis and the economics of such operations are sacrificed with the use of heavier underpads. Thus the repellent plastic film is usually secured to a textile sheeting fabric having a count of at least about 48 x 44 since a more open fabric would not provide good adherence and the shrinkage of the fabric would be such as to cause problems of separation. Preferably this textile sheeting is of high count, however, the economics involved provide a commercial ceiling.
The repellent plastic sheeting must not shrink during repeated launderings such as to exhibit greater than about a 3% total loss in either the length or width of the pad. A greater shrinkage in either direction would establish separation between the backing sheet which is secured to the repellent film. This would also place a severe strain on the stitching holding the plastic film in place in the underpad together with resultant fabric bunching along the. edges of the underpad.
As used herein laundry cycle and laundering shall be synonymous and shall be defined with respect to a Prosperity Junior Washer, Model 20, Serial No. 1054, utilizing a normal wash load of 20 pounds of underpads where a first washing shall initiate the cycle and shall comprise adding l2 gallons of water at about 160 F. to a charge consisting of 15 grams of White Ribbon Chip Soap sold by Hampden Color and Chemical Company, cc. of Chlorox chlorine bleach, l5 grams of soda ash and 8 grams of Calgon water conditioner, and agitating for fifteen minutes. This is followed by a second washing which is a repeat of the first washing cycle except that the charge consists of 8 grams of White Ribbon Chip Soap, 8 grams of soda ash and 2 grams of Calgon water conditioner. This second washing cycle is followed by four, five minute rinse cycles where the first two shall each utilize 24 gallons of water at F. and the last two shall each utilize 24 gallons of unheated normal tap water, except that with the last rinse there shall be added 100 cc. of Velva-Soft G, sold by Armour & Company and 2 grams of zinc silicon uoride. The cycle timer for automatic control is Formatrol, Model FA 2093, No. 4777.
As used herein drying and drying cyclef shall be synonymous and shall consist of drying such normal wash loads of underpads in a Huebsch Gas Dryer, Ser. No.. 67,093, at 200 F. for twenty minutes.
The absorbent fabric used in the underpad of this invention should be soft and is preferably gauze diaper fabric. This fabric must be present in an amount sufficient to satisfy the minimum absorbency required of such an underpad, yet present in an amount sufiicient to prevent overflow of fiuids from the face of the underpad.
Diaper fabric is usually low count woven cotton fabric. It is characterized by a woven construction of warp and filling yarns wherein the warp yarns extend substantially parallel to the length of the fabric and the fill yarns extend in the widthwise direction of the fabric, which is usually produced in continuous length. This fabric may have a plain, twill, Sateen, satin, birdseye, etc., weave, all of which are familiar to those skilled in the art.
Because of techniques of spinning, weaving and finishing used in the manufacture of cotton fabrics, the fabric as a whole is usually under tension due, for example, to the twist of the yarn, the weave, etc.; therefore, it must be appreciated that it will be stretched to a greater or lesser extent. Washing, or laundering of the fabric, will quite naturally relieve the tension and with the internal tension relieved the fabric will, on drying, change in dimension since the individual yarns will assume positions closer to the adjacent yarn member of the fabric throughout, and the interstces between yarn will be lessened appreciably.
Thus, the original unit area of the fabric is diminished. It
is the result of this diminution of fabric and the effect it produces in the underpad that is overcome by this invention.
The fabric used in underpads of this invention is that which is considered and known by the art as gauze diaper fabric, however, any absorbent fabric ordinarily used in diapers can be substituted therefor. Thus, within this definition and considering the then appropriate yarn sizes, the fabric will only be so open as is acceptable for diaper fabric measured in terms of acceptable absorbency, strength, softness or lack of roughness, corrugation and abrasion resistance.
The invention will be more readily understood by refence to the accompanying drawings wherein:
FIG. 1 is a planar view of a prior art lauderable underpad with a cutaway portion showing its construction,
FIG. 2 is the underpad of FIG. 1 shown in a state representative of the actual physical state and appearance that it would present after having undergone about twenty-five laundering and twenty-five complementary drying cycles,
FIG. 3 is a cross section taken along line 3-3 of FIG. 2,
FIGS. 4 and 5 are planar views of embodiments of diapers of this invention, and
FIG. 6 is a cross section taken along line 6-6 of FIG. 5.
After the pad of FIG. 1 has been subjected to about ten each of such laundering and drying cycles, the vinyl plastic repellent layer 4 has undergone about a 1 to 2% reduction in both the lengthwise and widthwise directions while the layers of gauze fabric 2, 3 and 5 have undergone about a 12% to 15% over-all reduction in each such direction. As a result, the physical appearance of the pad 1 is similar to that depicted via FIG. 2 except that the fabric failure depicted Iby holes 9 in fabrics 2 and 3 of the pad have ordinarily not yet occurred. However, the terminal edges 7 of the pad 1 have begun to curl up due to the differential in shrinkage that exists between the shrinkage of repellent layer 4 and that of the fabrics 2, 3 and 4. Additionally, corrugation or internal bunching of the repellent layer 4 is evidenced by corrugation in the pad 1.
After about twenty-five washing and drying cycles the pad 1 appears substantially as it is depicted in FIG. 2 and is shown by the enlarged cross section which is FIG. 3 and is taken along line 3-3 of FIG. 2. The vinyl plastic repellent layer 4 has begun to stilen and cracks 8 begin to appear. The areas of corrugation 10, whether or not they are accompanied by cracks 8 and the upturned edges defining so many of these cracks, receive the brunt of the abrasive wear that the pad 1 receives. This localized abrasive wear causes the premature fabric failure, represented by holes 9, resulting in the exposure of the stitfened plastic repellent layer 4. The cracks 8 of the stiffened plastic layer 4 present sharp edges, as do the upturned exposed terminal edges 7 of the stiffened plastic layer 4. These edges act in a fashion suggestive of a knife blade, to scratch and cut the exposed skin of one lying on the pad 1 and to cause damage to articles of clothing or bedding with which they come into contact.
The areas of corrugation 10 caused by the localized bunching of the repellent layer 4 due to the greater shrinkage in the gauze diaper fabrics 2, 3 and 5 which confines and lessens the over-all area of the repellent layer 4, provide many areas `of localized discomfort since the original flat surface of the pad is destroyed. Additionally, repeated use and laundering of the pad 1, which is defined by multi-ply cloth and where there is substantial freedom between the plies of cloth, is usually attended by fabric pilling. This is due to the natural abrasion acting on the surface of the cloth of layers 2 and 3 during washing, drying and every day use, etc. whereby fiber pills are detached from the material and are trapped between the absorbent layers of the pad and the water repellent layer.
These fiber pills gather and, largely through the action of the forces attending the aforementioned actions of washing, drying and normal use, form into small balls 11 which also provide points of discomfort to the user, and which are potential sources of skin irritation. These fabric balls 11 also provide points of high spotting and resultant premature wear.
The stiffening of the vinyl plastic of the repellent sheet 4 is caused by the leaching out of the plasticizer during repeated laundering and drying. The resulting loss of exibility causes the cracks which destroy the functionality of the repellent layer 4. Many other plastics or synthetic sheet materials which have good fiex life built into them by the use of a plasticizer, undergo similar results when they are exposed to repeated laundering and drying cycles.
The liquid repellent layer of this invention must consist of a material which is flexible and retains sufiicient of its flexibility after undergoing at least about one hundred each of the laundering and drying cycles defined herein, to exhibit good flexibility and no cracking. It should also have good dimensional stability under these same conditions such that its shrinkage is no more than about 3% in either the lengthwise or the widthwise directions and is must be a material which is not a skin irritant. Butyl rubber is the preferred member of the several materials that satisfy these requirements. Other such materials are acrylic polymers and silicone rubber.
As discussed earlier, the repellent layer of this invention may be a plastic sheet in, and of, itself in which case a ply of backing fabric must be superimposed in facewise engagement with each of its faces, or it may be coated onto a fabric such as ordinary sheeting material, to provide a coated fabric layer which is water repellent.
FIG. 4 is a planar view of one embodiment of an absorbent pad of this invention. The absorbent pad 20 consists of two plies 21 and 22 of gauze diaper fabric and a backing sheet 23 which is also the water repellent ply of the pad 20. The backing sheet 23 is constructed of two plies, one ply of 68 x 72 crib sheeting material shown in cutaway and shown with one corner upturned to expose the outer surface or face 25. This backing ply 23 has its inner surface 24, i.e. the surface in facewise engagement with the inner ply 22 of gauze diaper fabric, coated with a layer of butyl 'rubber which has been calendered onto the sheeting. The exposed facing surface 25 of the repellent layer 23 presents lthe soft surface of the crib sheeting material and is the surface that forms the backing face of the pad `20.
The butyl rubber coating on the backing ply 23 is applied in an amount sufficient to insure impermeability to urine and other such liquids which it is meant to bar. The butyl coating is thus present in an amount of preferably 7 to 8 ounces per square yard to provide a substantially uniform coating thickness throughout this surface of the sheeting material, of at least about 0.008 inch. This ensures that tufts or errant fiber protrusions which might provide sites of liquid seepage are eliminated.
The gauze plies 21 and 22 are secured together by overedge stitching 26 while the backing ply 23 is sewn to the composite of fabric by safety stitching 27. Openings 28 and 29 between the fabrics 21 and 22 and the backing ply 23 are strategically located at diagonally opposed edges to provide maximum ensurance that pills formed during use, etc. can escape. This then eliminates the high spotting that has caused localized discomfort sites and has provided sources of skin irritation to incontinent patients and has provided spots of premature fabric failure.
Note that the composite of plies 21 and 22 is present in excess as is shown by the fabric bunching 30 in the pad 20 of FIG. 4. This is constructed into the pad 20 to compensate for the differential in over-all shrinkage between the fabric plies 21 and 22 and that of the backing ply 23.
The backing ply 23 will undergo about a 2% lengthwise and widthwise shrinkage during repeated launderings, while the gauze plies 21 and 22 will each experience about a 12% shrinkage in the same directions. The shrinkage differential is thus about total in any one given dimension. To preclude corrugation in the pad 20, this 10% shrinkage differential is actually determined with respect to the dimensions of the diaper cloth utilized in plies 21 and 22, and the pad 20 is constructed such as to readily accept this shrinkage differential and to thus preclude the aforediscussed corrugation phenomena which establishes localized sites of discomfort and premature wear in an underpad. For example, if the original underpaid (unwashed) is to be thirty-six inches long, a four inch excess in the length of each gauze ply 21 and 22 would be provided. The same procedureis followed with res-pect to the width of the underpad which is normally twenty-four inches and thus has about two and one-half inches provided. This excess material is constructed into the underpad by differential feed sewing.
The unwashed underpad of this invention will thus present an apparent surplusage of diaper fabric, or other such absorbent fabric, represented by the excess material constructed into the pad to overcome the shrinkage differential in the materials of the pad; however, about 75% to 80% of the shrinkage in both the backing ply 23 and the `ganz/e plies 21 and 22 does take place in the first laundering and drying cycle, with only about 2% to about 5% residual shrinkage remaining in the materials after the first four or five such launderings and dryings. Thus the excess material is soon dissipated. FIG. 5 is presented to depict the underpad of FIG. 4 after about fifty each laundering and drying cycles. Note that no corrugation, high spotting, holes in the fabric or cracks in the backing ply do appear.
Fabric pills are substantially eliminated by providing the two diagonally situated openings 28 and 29. The openings are about four inches in length in the periphery of the pad 20 (which is a 36 x 24 inch pad) and provide free access to the area Within the underpad 20. Surprisingly, the pills created by Wear, laundering and drying are eliminated automatically during the washing or drying cycles through these openings 28 and 29.
FIG. 6 is a cross section taken through 5 5 of FIG. 5 and depicts the nature of the openings 28 along with the fiat nature of the underpad itself. There is no corrugation, pilling or cracking present.
While the instant invention is designed to function as an underpad, it could well function as a diaper.
The instant invention has been described in connection 'with its preferred embodiments, but many modifications thereof are easily included without departing from the inventive concept which is limited only by the scope of the appended claim.
What is claimed is:
1. A launderable underpad comprising a plurality of plies of diaper fabric superimposed in facewise engagement and a sheet of flexible water impervious material secured in facewise engagement to at least one ply of said fabric, said fabric being present in sufficient excess to satisfy the shrinkage differential between said lwater impervious sheet and said underpad having specifically located openings for removal of fiber pills.
References Cited UNITED STATES PATENTS 2,685,290 8/ 1954 IOBrien 12S-287 2,803,836 8/1957 Hunsicker 5--334 2,963,715 12/1960 Young 5-354 X 3,150,663 9/ 1964 Combs 128-287 3,316,566 5/ 1967 Long 5-334 CASMIR A. NUNBERG, Primary Examiner.
U.S. Cl. X.R.