CA2149325C - Absorbent including super absorbent and capacity monitor - Google Patents
Absorbent including super absorbent and capacity monitor Download PDFInfo
- Publication number
- CA2149325C CA2149325C CA002149325A CA2149325A CA2149325C CA 2149325 C CA2149325 C CA 2149325C CA 002149325 A CA002149325 A CA 002149325A CA 2149325 A CA2149325 A CA 2149325A CA 2149325 C CA2149325 C CA 2149325C
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- Canada
- Prior art keywords
- indicator
- diaper
- absorbent
- backing sheet
- capacity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/42—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators with wetness indicator or alarm
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/42—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators with wetness indicator or alarm
- A61F2013/426—Moisture sensitive polymers
Abstract
A capacity monitor for diapers (10) and the like, including super absorbent material disposed in or adja-cant to an absorbent core ( I6) is disclosed: The monitor (20) comprises an indicator (24) and a baffle (22) to pre-vent direct contact between the absorbent core and the indicator. The indicator (24) is preferably a ribbon of hot melt adhesive with a wetness indicator which changes color when exposed to liquid. The baffle (22) is a substantially water impervious sheet positioned be-tween the absorbent core ( 16) and the indicator (24) so as to prevent direct contact between them. The diaper (10) and the monitor (20) are constructed so that there is a threshold level of liquid which, when deposited in the diaper, will effect a color change in the indicator (24). A
quantity of liquid which is below the threshold will not effect a color change in the indicator (24) and a quanti-ty of liquid which is above the threshold will effect a co-for change in the indicator (24).
quantity of liquid which is below the threshold will not effect a color change in the indicator (24) and a quanti-ty of liquid which is above the threshold will effect a co-for change in the indicator (24).
Description
WU 94/10958 ~ ~~ 4 ~ a . ~ ~ ' PCT/US93/10890 --ABSORBENT INCLUDING SUPER ABSORBENT AND CAPACITY MONITOR--BACKGROUND OF THE INVENTION
1. Field of the Invention.
This invention relates to the field of absorbent products including super absorbent polymers, especially foe use try persons with urinary incontinence. More specifically, the invention relates to such products including a sensor or monitor which provides an 1:0 indication when thG absorption capacity of the super absorbent polymer has been exceeded.
'. Dcscriptiort of the Prior Art here are numerous examples of wetness indicating devices which have been proposed for use in diapers and other absorbcnc products foe use by persons with urinary incontinence.
Onc example of a wetness indicator is represented by a class of hot melt adhesive products which include a wetness indicating component: US Patent Nos. 4,743,238, 6,035,691, 5,066,711 and 5;089,548 disclose various hot melt adhesives with wetness indicators, many of which would be suitable for use in a. capacity monitor according to the present invention.
These hot melt products arc in wide use in disposable diapers today. In conventional use, they are applied in the forrtti of a narrow straight bead, a thin ribbon or a spiral bead to a water impervious backing sheet and are in direct contact~with; and in liquid communicable relation with, an absorbent layer of fluff. Tests conducted on scvcr~l commercially available disposable diaper products including uch conveneionally applied hot melt adhesives with wetness indicators demonstrate that the wetness indicators provide a positive indication of wetness, i:c;, a color change in the hot melt, when no more than 1 ~
milliliters of a U:9~'o NaCI solution was deposited thcrcc~n: Even 3 milliliters of such solution was sufficient to ''effect a color change in some of the conventionaC applied hot melt adhesives with'wctness indicator. The color change occtsrrcd over relatively short tcneths, i.c., betwecn'r: inch and and 'fx inches, of the beads or ribbons of hot melt adhcsiv~ with wetness indicator at the low volume levels of 6 to 16 milliliters.
US Patent No3.731686 discloses a mpisturc indicating strip which is designed for use with diapers: and other absorbent products. One end of the strip is attached to the inside of the diaper or the like and the other end, which is impregnated with a color change chcnnical. ' extends out of the diaper. Liquid is transported by capillary action from inside the diaper or the like to the color change chemical outside the diaper.
WO 94/10958 . ~ ~ ~ ~ ~ ~ ~ , ~ , ~ PGT/US93/10890 ~~ i US Patent No. 3,759.261 discloses diapers having a layer with a pattern printed thereon <..
and one or more layers which maskath~ pattern when dry. When wetted, the masking layers .; .
no longer mask the pattern which ~ becomes visible through a backing sheet, thereby providing a wetness indicating function.
US Patent No. 3,952,746 discloses a humidity indicator strip incorporated in a diaper including a water impervious backing sheet. A portion of the strip extends through an , opening formed in the backing sheet.
US Patent No. 4;02~;?11 discloses a diaper including a wetness indicator comprising a layer of water soluble or water dispersible coloring agent applied to the water impervious backing sheet. Vlrhen dry, the coloring agent is clearly visible through the backing sheet but, when wetted, the coloring agent is dispersed and is no longer visible through the backing sheet.
US Patent No. 4,231.370 discloses a wetness indicator in a diaper structure.
The wetness indicator is positioned between a water impervious backing sheet and an absorbent core and comprises a flexible pH-changc/colar-change coating which is preferably applied to the backing sheet and visible thcrcthrough. The preferred coating material comprises first and second latexes, an acid buffer and bromo-phenol blue.
US Patent No. 4 ~$?;153 discloses a diaper including a saline water indicating material positioned between a backing sheet and an absorbent core, and visible through the backing sheet; The preferred indicating material comprises ' a water-insoluble polymeric ion exchanger and a water-insoluble polymeric exchanged ion indicator in intimate contact with each other.
US Patent No. 4,S0?,121 discloses a diaper including a wetness indicator comprising a color change chemical which is isolated from the absocbcnt portions of the diaper so 'as to prevent contact between a wearer of the tiiapcr and the color change chemical. Means are provided for supporting one way capillary action to transport liquid from the absorbent portions to the indicator to trigger the color change.
US Patent No. 4,704,108 discloses a wetness indicator comprising. two metal strips incorporated in a diaper and circuitry far detecting changes in the electrical conductivity in absorbent portions of the diaper due to the presence of moisture therein.
US Patent No. 4,?05,513 discloses a wetness indicator for diapezs. The indicaeor comprises ' indicts printed in waterproof ink on a paper carrier strip. !fig paper strip is positioned adjacent to a wator impervious backing sheet and the indicia is masked by the strip so long as it remains dry. When wetted, ~hc carrier strip no longer masks the indicia and it becomes visible through the backing sheet to indicate wetness.
US Patent No. 4,738,674 discloses an absorbent product including a moisture indicator which provides an indication of wetness at a point remote from where liquid is actually deposited on the product. The indicator includes a wicking strip for transporting liquid from a point where it is deposited to an edge of the product where it contacts a moisture indicating substance which can provide a visual indication, such as a color change, that it has been wetted.
US latent No. 4,834,733 discloses a diaper including an actuating member which shrinks when wetted and it is connected to an indicating mechanism so that, when moisture contacts the actuating member, it shrinks and displaces the indicating me~anism providing an indication that fluid has been deposited in the diaper.
US Patent No. 5,078,7U8 discloses a diaper comprising a transparent or translucent, water impervious backing sheet and an absortxnt core. Opening are provided in the core so that urine or stools deposited in the diaper arc visible through the backing sheet to indicate the need for a change.
Super absottxnt materials have been incorporated itt commercially available diapers and the like, for many years. US Patent No. 5,U72,687.
discloses several varieties of absorbent diaper products including sups absorbent materials. Known super absofbcnts absorb large amounts of liquid and liquid absorbed in super absorbents can not be squeezed back out of the super absorbents. This is to be contrasted with fluff which is compvscd of cellulose or the like fibers.
Fluff can absorb many times its weight in liquid but liquid absorbed in fluff can tx squeezed back out of the fluff. In a diaper, squeeze out of urine from fluff can cause leakage and prolonged skin contact with urine soaked fluff can cause damage to healthy skin and inhibit healing of damaged skin.
Each super absorbent polymer has a "speed" which is used herein to mean the rate at which the super absorbent will absorb liquid. The speed of a super absorbent depends upon many factors including its composition, the quantity of liquid it has alrtady absorbed and the amount of liquid available to,bc absorbed. 1=or a given liquid, each super absorbent also has a "free swell capacity" which is used herein to mean the maximum amount of liquid which unrestrained super absorbent particles will ultimately absorb when exposed to an excessive amount of a liquid, i.e., one which fat exceeds the capacity of the super absorbent h WQ 9R/1095g ~ ~ ~ ~' '~ PCT/US93/1Og90 ,~..
~:<:...:.;
..«;;
relative to that liquid. A given super absorbent with a given capacity for a given liquid will have a different, somewhat lower capacity for that liquid when the super absorbent is contained in, for example, an absorbent core of a diaper. The term "in--situ capacity" will be used hereinafter to refer to the volume of a given liquid which is absorbed by super absorbent associated with an absorbent core containing at least oneother, different absorbent material, such as fluff, within thirty minutes after the liquid is..clcposited slowly in a single spot in the absorbent core. The in-situ capacity of super absorl~eitt in such an absorbent core does not include the capacity of the fluff or other absorbenf~~rinaterial in the core; the term refers only to the capacity of the super absorbent to absorb a given liquid, under the recited 1U conditions, within thirty minutes of the time tht: liquid is deposited.
Some super absorbents arc fast and some are slow. In granular form, commercially available super absorbents take approximately one to three minutes to absorb their free swell capacity of water, when unrestrained and exposed to large amounts of water.
When super absorbents are incorporated in absorbent cores with other absorbent materials, such ,as fluff, they absorb liquid more slowly than this, largely because they are in contact with less Liquid.
All super absorbents have a given speed when drSA, and, as they absorb liquid, the speed and remaining capacity of the super absorbent, decreases.
Same of the characteristics discussed in the preceding paragraph are illustrated in Fig.
1 in respect of super absorbents contained in absorbent fluff cores in diapers. Fig. 1 is a plot of data collected from tests made of a commercial ~rsion of several medium sized SIimLine~ diapers manufactured by Principle Business Enterprises, Ine. In the test; many different quantities of a U.9% NaCI solution were deposited on SlimLine medium size diapers. For each quantity of solution, the diapers were tested for skin wetness at different intervals of time after the solution was deposited. In the skin wetztess test, a medium size SlimLinc diaper was placed, with its water impervious backing sheet facing downwardly, on a level surface: In the center of the diaper, a given quantity of a~U.9%
NaCI solution was deposited at the rate of 7.U milliliters per second: Absorbent, paper toweling, cut into three inch by five inch rectangles, was stacked, the stack was weighed and its dry weight was recorded. At various time intervals after the U.9% NaCI solution had been deposited an the diaper, a previously weighed stack of paper toweling was placed on top of the diaper and a three inch by five inch: z~cctangularlv shaped five potmd weight was placed om top of the paper toweling. After fifteen seconds; the weight was removed from the paper toweling and it was reweighed. The weight of the dry toweling was subtracted from the weight of the wet . :~ I..~~ , ~; f !I
paper toweling to give a skin wetness number corresponding with the weight of 0.996 NaCI
solution which was released by the diaper into the paper toweling. The time which elapsed before the skin wetness number was 0.0 grams for a given quantity of liquid was plotted for several different quantities of liquid and the results arcshown in Fig. 1. The medium sized SlimLine diapers which were tested had 12 grams of Aridall 1465 super absorbent material-, ', available from trltemdal, in the fluff layer. At relatively low volume levels, the speed of the super absorbent in the Sliml.inc diapers is relatively fast, as rc(lcctcd by the steep slope of the plot on the Ieft~side of Fig. 1. At higher volume levels, the slope of the plot is not as steep and this reflects the well known phcnontcnon associated with super absorbents used in absorbent products, namely, the speed of a super absorbent irtaterial daxease~ as it absorbs.liquid. As the capacity of thc~sttpcr absorbent is used up, the~-deed decreases and the slope of a plot like that shown in Fig. 1 approaches zero. It will be appreciated that the in-situ capacity of the super absorbent in a medium SIimLinc diaper for synthetic urine is approximately 400 to 450 milliliters. The plot in Fig. 1 provides a good way to approximate in-situ capacity because, for example, the fluid volume of about 425 milliliters at thirty minutes elapsed is almost entirely absorbed within the super absorbent material, whereby the skin wetness number is 0.0 because the super absorbent dues not release liquid under pnssurc. The volume :of 285 milliliters associated with a skin wetness of 0.0 after ten minutes is significant, in terms of the medium SIimLinc, because it is preferred that skin not be in contact with a diaper with skin wetness in excess of O.U for mere than ten minutes.
In a SlimLinc diaper, which comprises a substantial quantity of absorbent cxllulose fluff (70 grams) as well as the 12 grams of super absorbent polymer, liquid is immediately absorbed into the fluff rnmponent and, over time, the liquid is withdrawn from the fluff and absorbed by the super absorbent polymer. So long as the in-situ capacity of the super absorbent is not exceeded by the quantity of liquid. the fluff layer will, within thirty minutes, dry out in the sense that it will preferentially give up absorbed liquid for absorption by the super absorbent polymer in the diaper.
it tias been determined that urine absorbed in and held by super absorbent material in a disposable diaper is innocuous to a wearer and skin adjacent to and in contact with a diaper which contains urine held by super absorbent material (and no urine held in a fluff layer) is not damaged by such contact. This is true even for relatively large volumes of urine such as 100 or 200 milliliters. Prolonged exposure of skin to urine, either direct exposure to urine or exposure to urine which is atxtorbcd in fluff, can damage healthy skin by causing *Trade-mark r '~ s~ ; ii r a rash or other reaction while prolonged ezposurc of already damaged skin can inhibit hearing and aggravate the damage to the skin:
As noted above, when only 15 milliliters of 0.996 NaCI solution is applied to commercially available diapers including conventionally applied hot melt adhesives with .
wetness indicators, the wetness indicators change color signalling the need for a change of the diaper. 'this was true, even for commercially available diap~:rs which included super .' absorbent materials. It will be appreciated that such use of hot melt adhesives with wetness indicators in a SIimLinc diaper, or other diaper including super absorbent material, would provide,,in many cases, a premature indication of the need for a diaper change because:
1. it takes a~roximatciy two minutes for the super. absorbent polymer in medium Slim_ Linc diapers .to completely atisofb 100 milliliters of 0.99t~ NaCI solution (0.0 skin wetness) but-the~super absorbcnt has a rcmaininR in-situ capacity to completely absorb, in ten minutes, another 2.t)0 milliliters of 0.996 NaCI solution;
1. Field of the Invention.
This invention relates to the field of absorbent products including super absorbent polymers, especially foe use try persons with urinary incontinence. More specifically, the invention relates to such products including a sensor or monitor which provides an 1:0 indication when thG absorption capacity of the super absorbent polymer has been exceeded.
'. Dcscriptiort of the Prior Art here are numerous examples of wetness indicating devices which have been proposed for use in diapers and other absorbcnc products foe use by persons with urinary incontinence.
Onc example of a wetness indicator is represented by a class of hot melt adhesive products which include a wetness indicating component: US Patent Nos. 4,743,238, 6,035,691, 5,066,711 and 5;089,548 disclose various hot melt adhesives with wetness indicators, many of which would be suitable for use in a. capacity monitor according to the present invention.
These hot melt products arc in wide use in disposable diapers today. In conventional use, they are applied in the forrtti of a narrow straight bead, a thin ribbon or a spiral bead to a water impervious backing sheet and are in direct contact~with; and in liquid communicable relation with, an absorbent layer of fluff. Tests conducted on scvcr~l commercially available disposable diaper products including uch conveneionally applied hot melt adhesives with wetness indicators demonstrate that the wetness indicators provide a positive indication of wetness, i:c;, a color change in the hot melt, when no more than 1 ~
milliliters of a U:9~'o NaCI solution was deposited thcrcc~n: Even 3 milliliters of such solution was sufficient to ''effect a color change in some of the conventionaC applied hot melt adhesives with'wctness indicator. The color change occtsrrcd over relatively short tcneths, i.c., betwecn'r: inch and and 'fx inches, of the beads or ribbons of hot melt adhcsiv~ with wetness indicator at the low volume levels of 6 to 16 milliliters.
US Patent No3.731686 discloses a mpisturc indicating strip which is designed for use with diapers: and other absorbent products. One end of the strip is attached to the inside of the diaper or the like and the other end, which is impregnated with a color change chcnnical. ' extends out of the diaper. Liquid is transported by capillary action from inside the diaper or the like to the color change chemical outside the diaper.
WO 94/10958 . ~ ~ ~ ~ ~ ~ ~ , ~ , ~ PGT/US93/10890 ~~ i US Patent No. 3,759.261 discloses diapers having a layer with a pattern printed thereon <..
and one or more layers which maskath~ pattern when dry. When wetted, the masking layers .; .
no longer mask the pattern which ~ becomes visible through a backing sheet, thereby providing a wetness indicating function.
US Patent No. 3,952,746 discloses a humidity indicator strip incorporated in a diaper including a water impervious backing sheet. A portion of the strip extends through an , opening formed in the backing sheet.
US Patent No. 4;02~;?11 discloses a diaper including a wetness indicator comprising a layer of water soluble or water dispersible coloring agent applied to the water impervious backing sheet. Vlrhen dry, the coloring agent is clearly visible through the backing sheet but, when wetted, the coloring agent is dispersed and is no longer visible through the backing sheet.
US Patent No. 4,231.370 discloses a wetness indicator in a diaper structure.
The wetness indicator is positioned between a water impervious backing sheet and an absorbent core and comprises a flexible pH-changc/colar-change coating which is preferably applied to the backing sheet and visible thcrcthrough. The preferred coating material comprises first and second latexes, an acid buffer and bromo-phenol blue.
US Patent No. 4 ~$?;153 discloses a diaper including a saline water indicating material positioned between a backing sheet and an absorbent core, and visible through the backing sheet; The preferred indicating material comprises ' a water-insoluble polymeric ion exchanger and a water-insoluble polymeric exchanged ion indicator in intimate contact with each other.
US Patent No. 4,S0?,121 discloses a diaper including a wetness indicator comprising a color change chemical which is isolated from the absocbcnt portions of the diaper so 'as to prevent contact between a wearer of the tiiapcr and the color change chemical. Means are provided for supporting one way capillary action to transport liquid from the absorbent portions to the indicator to trigger the color change.
US Patent No. 4,704,108 discloses a wetness indicator comprising. two metal strips incorporated in a diaper and circuitry far detecting changes in the electrical conductivity in absorbent portions of the diaper due to the presence of moisture therein.
US Patent No. 4,?05,513 discloses a wetness indicator for diapezs. The indicaeor comprises ' indicts printed in waterproof ink on a paper carrier strip. !fig paper strip is positioned adjacent to a wator impervious backing sheet and the indicia is masked by the strip so long as it remains dry. When wetted, ~hc carrier strip no longer masks the indicia and it becomes visible through the backing sheet to indicate wetness.
US Patent No. 4,738,674 discloses an absorbent product including a moisture indicator which provides an indication of wetness at a point remote from where liquid is actually deposited on the product. The indicator includes a wicking strip for transporting liquid from a point where it is deposited to an edge of the product where it contacts a moisture indicating substance which can provide a visual indication, such as a color change, that it has been wetted.
US latent No. 4,834,733 discloses a diaper including an actuating member which shrinks when wetted and it is connected to an indicating mechanism so that, when moisture contacts the actuating member, it shrinks and displaces the indicating me~anism providing an indication that fluid has been deposited in the diaper.
US Patent No. 5,078,7U8 discloses a diaper comprising a transparent or translucent, water impervious backing sheet and an absortxnt core. Opening are provided in the core so that urine or stools deposited in the diaper arc visible through the backing sheet to indicate the need for a change.
Super absottxnt materials have been incorporated itt commercially available diapers and the like, for many years. US Patent No. 5,U72,687.
discloses several varieties of absorbent diaper products including sups absorbent materials. Known super absofbcnts absorb large amounts of liquid and liquid absorbed in super absorbents can not be squeezed back out of the super absorbents. This is to be contrasted with fluff which is compvscd of cellulose or the like fibers.
Fluff can absorb many times its weight in liquid but liquid absorbed in fluff can tx squeezed back out of the fluff. In a diaper, squeeze out of urine from fluff can cause leakage and prolonged skin contact with urine soaked fluff can cause damage to healthy skin and inhibit healing of damaged skin.
Each super absorbent polymer has a "speed" which is used herein to mean the rate at which the super absorbent will absorb liquid. The speed of a super absorbent depends upon many factors including its composition, the quantity of liquid it has alrtady absorbed and the amount of liquid available to,bc absorbed. 1=or a given liquid, each super absorbent also has a "free swell capacity" which is used herein to mean the maximum amount of liquid which unrestrained super absorbent particles will ultimately absorb when exposed to an excessive amount of a liquid, i.e., one which fat exceeds the capacity of the super absorbent h WQ 9R/1095g ~ ~ ~ ~' '~ PCT/US93/1Og90 ,~..
~:<:...:.;
..«;;
relative to that liquid. A given super absorbent with a given capacity for a given liquid will have a different, somewhat lower capacity for that liquid when the super absorbent is contained in, for example, an absorbent core of a diaper. The term "in--situ capacity" will be used hereinafter to refer to the volume of a given liquid which is absorbed by super absorbent associated with an absorbent core containing at least oneother, different absorbent material, such as fluff, within thirty minutes after the liquid is..clcposited slowly in a single spot in the absorbent core. The in-situ capacity of super absorl~eitt in such an absorbent core does not include the capacity of the fluff or other absorbenf~~rinaterial in the core; the term refers only to the capacity of the super absorbent to absorb a given liquid, under the recited 1U conditions, within thirty minutes of the time tht: liquid is deposited.
Some super absorbents arc fast and some are slow. In granular form, commercially available super absorbents take approximately one to three minutes to absorb their free swell capacity of water, when unrestrained and exposed to large amounts of water.
When super absorbents are incorporated in absorbent cores with other absorbent materials, such ,as fluff, they absorb liquid more slowly than this, largely because they are in contact with less Liquid.
All super absorbents have a given speed when drSA, and, as they absorb liquid, the speed and remaining capacity of the super absorbent, decreases.
Same of the characteristics discussed in the preceding paragraph are illustrated in Fig.
1 in respect of super absorbents contained in absorbent fluff cores in diapers. Fig. 1 is a plot of data collected from tests made of a commercial ~rsion of several medium sized SIimLine~ diapers manufactured by Principle Business Enterprises, Ine. In the test; many different quantities of a U.9% NaCI solution were deposited on SlimLine medium size diapers. For each quantity of solution, the diapers were tested for skin wetness at different intervals of time after the solution was deposited. In the skin wetztess test, a medium size SlimLinc diaper was placed, with its water impervious backing sheet facing downwardly, on a level surface: In the center of the diaper, a given quantity of a~U.9%
NaCI solution was deposited at the rate of 7.U milliliters per second: Absorbent, paper toweling, cut into three inch by five inch rectangles, was stacked, the stack was weighed and its dry weight was recorded. At various time intervals after the U.9% NaCI solution had been deposited an the diaper, a previously weighed stack of paper toweling was placed on top of the diaper and a three inch by five inch: z~cctangularlv shaped five potmd weight was placed om top of the paper toweling. After fifteen seconds; the weight was removed from the paper toweling and it was reweighed. The weight of the dry toweling was subtracted from the weight of the wet . :~ I..~~ , ~; f !I
paper toweling to give a skin wetness number corresponding with the weight of 0.996 NaCI
solution which was released by the diaper into the paper toweling. The time which elapsed before the skin wetness number was 0.0 grams for a given quantity of liquid was plotted for several different quantities of liquid and the results arcshown in Fig. 1. The medium sized SlimLine diapers which were tested had 12 grams of Aridall 1465 super absorbent material-, ', available from trltemdal, in the fluff layer. At relatively low volume levels, the speed of the super absorbent in the Sliml.inc diapers is relatively fast, as rc(lcctcd by the steep slope of the plot on the Ieft~side of Fig. 1. At higher volume levels, the slope of the plot is not as steep and this reflects the well known phcnontcnon associated with super absorbents used in absorbent products, namely, the speed of a super absorbent irtaterial daxease~ as it absorbs.liquid. As the capacity of thc~sttpcr absorbent is used up, the~-deed decreases and the slope of a plot like that shown in Fig. 1 approaches zero. It will be appreciated that the in-situ capacity of the super absorbent in a medium SIimLinc diaper for synthetic urine is approximately 400 to 450 milliliters. The plot in Fig. 1 provides a good way to approximate in-situ capacity because, for example, the fluid volume of about 425 milliliters at thirty minutes elapsed is almost entirely absorbed within the super absorbent material, whereby the skin wetness number is 0.0 because the super absorbent dues not release liquid under pnssurc. The volume :of 285 milliliters associated with a skin wetness of 0.0 after ten minutes is significant, in terms of the medium SIimLinc, because it is preferred that skin not be in contact with a diaper with skin wetness in excess of O.U for mere than ten minutes.
In a SlimLinc diaper, which comprises a substantial quantity of absorbent cxllulose fluff (70 grams) as well as the 12 grams of super absorbent polymer, liquid is immediately absorbed into the fluff rnmponent and, over time, the liquid is withdrawn from the fluff and absorbed by the super absorbent polymer. So long as the in-situ capacity of the super absorbent is not exceeded by the quantity of liquid. the fluff layer will, within thirty minutes, dry out in the sense that it will preferentially give up absorbed liquid for absorption by the super absorbent polymer in the diaper.
it tias been determined that urine absorbed in and held by super absorbent material in a disposable diaper is innocuous to a wearer and skin adjacent to and in contact with a diaper which contains urine held by super absorbent material (and no urine held in a fluff layer) is not damaged by such contact. This is true even for relatively large volumes of urine such as 100 or 200 milliliters. Prolonged exposure of skin to urine, either direct exposure to urine or exposure to urine which is atxtorbcd in fluff, can damage healthy skin by causing *Trade-mark r '~ s~ ; ii r a rash or other reaction while prolonged ezposurc of already damaged skin can inhibit hearing and aggravate the damage to the skin:
As noted above, when only 15 milliliters of 0.996 NaCI solution is applied to commercially available diapers including conventionally applied hot melt adhesives with .
wetness indicators, the wetness indicators change color signalling the need for a change of the diaper. 'this was true, even for commercially available diap~:rs which included super .' absorbent materials. It will be appreciated that such use of hot melt adhesives with wetness indicators in a SIimLinc diaper, or other diaper including super absorbent material, would provide,,in many cases, a premature indication of the need for a diaper change because:
1. it takes a~roximatciy two minutes for the super. absorbent polymer in medium Slim_ Linc diapers .to completely atisofb 100 milliliters of 0.99t~ NaCI solution (0.0 skin wetness) but-the~super absorbcnt has a rcmaininR in-situ capacity to completely absorb, in ten minutes, another 2.t)0 milliliters of 0.996 NaCI solution;
2. in the two minutes that it takes for 1U0 milliliters of 0.9°Xo NaCI
solution to be absorbed out of the fluff into the super absorbent, that quantity of 0.996 NaCI solution in the fluff would trigger a color .
change in conventionally applied hot melt adhesives with wetness ~ indicators.
While this phenomenon might increase salts of SIimLinc diapers and other products incorporating conventionally applied hot melt adhesives with wetness indicators, it would also unneocssarily increase the bucdcn on already overburdened landfills as well as the burden on care givers who tend to the changing of absorbent products used by persons with urinary incontinence. So, there is demonstrated a steed for a capacity monitor which is capable of providing a reliable indication of when the in-situ capacity of super absorbent material has been exceeded, without providing a premature indication. such as when there is substantial remaining in-situ capacity in the super absorbent.
I I, , ',', ~II . 61 SUi~ARY OF THE INVENTION
According to one aspect of the present invention, there is provided a diaper including a capacity monitor, said diaper comprising an absorbent core including super absorbent material, a hydrophilic cover sheet and a water impervious, translucent or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper having a given in-situ capacity for synthetic urine, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said diaper adjacent to said backing sheet so that the change of the indicator is visually perceptible through said sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which synthetic urine can migrate from said absorbent core to said indicator, said baffle being operable to prevent the flow of synthetic urine into wetting relationship with said indicator when the diaper contains an amount of synthetic urine which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the diaper contains an amount of synthetic urine which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
According to another aspect of the present invention, there is provided a diaper including a capacity monitor, said diaper comprising an absorbent core comprising 6a i, a fluff component and a super absorbent component, a hydrophilic cover sheet and a water impervious, translucent or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper having a given in-situ capacity for synthetic urine, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said diaper adjacent to said backing sheet so that the change of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which synthetic urine can migrate from said absorbent core to said indicator, said baffle being effective, in cooperation with the components of the diaper, to prevent the flow of synthetic urine into wetting relationship with said indicator when the diaper contains an amount of synthetic urine which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the diaper contains an amount of synthetic urine which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
According to still another aspect of the present invention, there is provided a diaper including a capacity monitor, said diaper comprising an absorbent core including a fluff component and a super absorbent component, a hydrophilic cover sheet and a water impervious, translucent 6b i , or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper being operable to absorb up to a given, maximum quantity of a desired liquid to the extent that, ten minutes after deposition of said given amount of liquid, said diaper has a skin wetness number of substantially zero, said capacity monitor comprising a hot melt adhesive containing a color change indicator, and extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible color change when said hot melt adhesive is wet, said hot melt adhesive being positioned in said diaper adjacent to said backing sheet so that the change of color of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said hot melt adhesive and separate it from said absorbent core, said baffle having a width which is greater than that of said hot melt adhesive and a free edge around which liquid can migrate from said absorbent core to said hot melt adhesive, said baffle cooperating with the components of the diaper to control the migration of liquid from said at least one absorbent component to said indicator so that said given quantity of desired liquid deposited on the diaper produces a visually perceptible change over a predetermined length of said indicator and indicia provided on said diaper and visible through said backing sheet, said indicia being operable to indicate the predetermined length of said hot melt adhesive which undergoes a visually perceptible change when said given quantity of desired liquid is deposited on the diaper.
6c i , ~~
According to yet another aspect of the present invention, there is provided an absorbent product including a capacity monitor, said product comprising an absorbent core including super absorbent material, said core having a first and a second side, and a water impervious, translucent or transparent backing sheet, said backing sheet being positioned adjacent to said first side of said core and said super absorbent material in said absorbent product having a given in-situ capacity for liquid, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said absorbent product between said backing sheet and said core so that the change of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which liquid can migrate from said absorbent core to said indicator, said baffle being operable to prevent the flow of a liquid into wetting relationship with said indicator when the core contains an amount of the liquid which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the core contains an amount of the liquid which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
The instant invention is based upon the discovery of a capacity monitor which is operable to provide a visible signal when the in-situ capacity of super absorbent material in a given absorbent core has been, or is close to being, 6d I i. . ii exceeded by liquid absorbed in the absorbent core. In a diaper comprising a water impervious backing sheet and an absorbent core comprising fluff and super absorbent material, the monitor comprises an indicator, such as a hot melt adhesive with a wetness indicator between the absorbent core and the backing 6e 2~.~~3~a WO 94!10958 ' PGT/US93/10890 ,:~i~,.
~:, . .
sheet. The monitor further comprises a substantially water impervious baffle positioned between the absorbent core and the hot melt adhesive, to prevent substantial contact between the indicator and liquid contained in the absorbent core, except when the quantity of such liquid exceeds a predetermined threshold volume of liquid: The monitor may further comprise a strip of non-woven material, or the like, positioned between the indicator and the backing sheet to prevent sticking therebetween: When a quantity of liquid which exceeds the threshold volume of liquid is deposited in the diaper, some of the liquid will migrate around the baffh and trigger a color change or the like in the indicator. The threshold level -is predetermined, for a given diaper, relative to the in--situ eapacity of-the super absorbent !U material in the absorbent core of the diaper: Preferably, the threshold volume is at least 20%
of the in-situ capacity of the super absorbent. More preferably, the threshold is at !cast 3U%
of the in-situ capacity while 4U% is mare preferred still. In some cases, the threshold may approach or even exceed the in-situ capacity' of the super absorbent in the absorbent core, if the other absorbent material therein is adequate to 'take up the slack. 'W
hen a strip of non-woven material, or the like, is proyidcd between the indicator and the backing sheet, it facilitates the transfer of liquid from the core to the indicator so that a change in the indicator occurs reliably when the threshold amount is exeeedec3; thereby overcoming any tendency of the indicator to stick to the backing shoes and prevent a change in the indicator.
Iri cases where the threshold is substantially below the in-situ capacity of the . super absorbent; the monitor may further;comprisc printed i'~dicia which provides a visually discernible signal which, together with the degree or extent or length indicator which changes color or the like, provides an indication of the remaining in-situ capacity, if any, of the super absorbent material in the absorbent core.
FIG. 1 is plot of elapsed time before a prior art diaper including super absorbent material achieves a zero skin wetness number: versus quantity of liquid deposited in the diaper.
FIG. 2 plan view, partially broken away, of a diaper incorporating a capacity monitor according to the present invention.
FTG. 3 is a crass sectional view, taken along the lines 3 - 3 of Fig. 2, showing some details of the capacity monitor according to fhc present invention.
'1~0 94/k09S8 . ~ PCT/US93/10890 FIG. 4 plan view, partially broken away, of .. ~; :preferred embodiment of a diaper incorporating a capacity monitor according to~ the pi~esent invention.
FIG. 5 is,a cross sectional view, taken along the lines 5 - 5 of Fig. 4, showing some details of a preferred capacity monitor according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to Fig. 2, a disposable diaper is indicated generally at 10. The diaper 10 comprises a water impervious backing shcef 13, a non--woven facing sheet 14 which would contact a wearer's skin when the diaper 1U is in use and an absorbent core 16.
In acebrdance with the invention, the absorbent core has at least two absorbent 'components, which are illustrated in and discussed below in connection with Fig. 3. Specifically, the core 16 has an absorbent fluff component and -a Super absorbent cotttponent. In accordance with the present invention, the super absorbent may be incorporated into the absorbent core in ariy suitable manner including those disclosed in said US Patent No. 5,072,687. The patent discloses the deposition of particulate super absorbent into a fluff Layer or ball. Also disclosed is a construction wherein super absorbent is contained in a laminate, i.e., one of more sheets of tissue with super absorbent adhered to and supported thereon, and the laminate is incorporated in an absorbent core. A combination of these constructions is also disclosed where loose super absorbent particles arid laminate containing super absorbent are combined with an absorbent cellulose fluff ball. lfic~e components of diaper IO are .
conventional and are well known in the industry.
A portion of the water impervious backing sheet 12 has been cut away in Fig. 2 to illustrate a capacity monitor; according to the present invention, indicated generally at 20.
The monitor 20 comprises a baffle 22 which extends along the longitudinal centerline of the diaper 10 and an indicator 24 which'undergoes a visually perceptible change when wetted.
The indicator 24 is positioned between the backing sheet I?. and the absorbent core 16. The baftlc 22, in turn; is positioned between the absorbent core 1G and the indicator 24. The baffle 2,2 is operable to prevent contact between liquid held in the absorbent Gore 16 and the indicator 24. Tlte rnonitar 20 is constructed, however; so that when there is quantity of liquid in the absorbent core which approaches or exceeds the in-situ capacity of he super absorbent in the absorbent core, the some of the liquid will contact the inditratar 24 effecting a perceptible change in it. Further details of construction for the digger i0 as well as the capacity monitor 20 arc discussed below with reference to °Fig. 3.
~..i;'1i9 ;..Y WO 94/)10958 ~ ~ ~ ~ ~ ~ ~ . .. ~ : PCT/US93/10890 '~ :; J
The baffle 23 may comprises a sheet of polymeric, water impervious film or paper which has been treated ox coated to render it water impervious or substantially so. The baffle 22 is positioned between the absorbent core l6 and the water impervious backing sheet 12.
The core 16, as previously irxdicated, includes a fluff component 26 and a super absorbent component which, in the illustrated embodiment, comprises discreet particles of super absorbent 28 carried in the fluff 26. A layer of tissue 30 is positioned between the fluff 26 and the non-woven facing sheet 14. As disclosed in US Patent No. 5,072,687, a layer of laminate (not shown) may bG setbstitutcd for the tissue layer 30, or combined with it and positioned between the fluff layer 2G and the tissue Iaycr 30; The monitor 20 further comprises the indicator 24 which is positioned between the baffle 23 and the water impervious backing sheet 12, The baffle 2? physically separates the fluff layer 26 and the absorbent core 1 G from the indicator 24 so than there is no direct contact between the indicator 24 and the fluff layer 26 or the absorbent core 1G.
The baffle 22 is comprised, at leash in part, of a hydrophobic material so that it constitutes a .physical barrier to the flow of liquid from the fluff layer 26 through the baffle 22 to he indicator 24. With the baffle ?2 in place, liquid in the fluff layer 26 can reach the indicator 24 only if it travels around free edges 32 of the baffle and travels between the baffle 2? and the water impervious backing sheet 12 to reach the indicator 24.
So long as the volume of Liquid in the diaper is such that the liquid can be held tightly or fairly tightly in the absorbent components of the'absorbent core 16, the liquid will not reach the indicator.
When the volume of Liquid in the diaper exceeds the volume which the absorbent components of the core 16 can hold fairly ightiy; there will be excess Liquid in the diaper IO such as would tend to pooh or puddle adjacent to or on the surface of the backing sheet I2 near the baffle 22 and some of it would travel around the free edges 32 of the baffle 22 and teach the indicator. In other words, there is a threshold level of liquid which must be deposited on the absorbent core in order for any liquid to reach the indicator. Thus, the movement of liquid from the absorbent core 16 to the indicator 24 is enabled when there is enottglz liquid. The edges 32 of the baffle 22 are free edges in the sense that they are not adhered to he backing sheet 12. Care must be taken, in producing a diaper with a capacity monitor 20 according to the invention in case the diaper includes conventional lines of hot melt adhesive without a wetness indicator 33 to adhere the absorbent core 16 to the backing sheet''12. Such adhesive Lines 33 must-not completely adhere the free edges 32 of the baffle ?? to the backing sheet 12, or vice versa. Instead, the hot melt adhesive lines 33 would be positioned, as shown in Fig. 3, where they do not engage the free edges 32 of the bafflc'22.
The indicator 24 preferably comprises a hot melt adhesive with a wetness indicator. A
preferred iridicator material is NICOL-MELT 82525 'which is available ttuough Swift Adhesives or its parent Reichhotd Chemical. This particular hot melt material is translucent and has a yellow color when it is allied, for example, to the baffle, ?.?. or the water impervious backing sheet i2. In the illustrated embodiment, it is preferred that the indicator consist of a ribbon of the indicated hot melt adhesive with wetness indicator having a width of approximately one quarter to one half inch (0.5 to 1.5 centimeters) and a thickness of l0 about one mil (0.035 millimeter). Insofar as the operability of th'te~~present invention is ~r:~.
concerned, the indicator may be applied either to the backing sheet 13 or the baffle 22.
Upon contacting most liquids, including synthetic and non-synthetic urine, the NICOL-MELT will change color, at the contact areas, from a tight or faint translucent yellow to a relatively dark and deep blue. This color change is readily pcroeivable through the water impervious cover 12 which, as previously mcntioried, is transparent of translucent.
The baffle 22 has a width which exceeds the width of the indicator 24.
Consequently, free edge portions 32 of the baftlc ?3 overlap edges 34 of the indicator 24, thereby hindering liquid in the absorbent core 16 from traveling to the indicator 24.
Good results have been obtained with a coated paper baffle having a width of approximately bnc and one quarter inches (3 centimeters) and an indicator.having a width of about vne quartet inch, so that at (cast one half inch (1 ~5 centimeters) of the baffle overlapped the edge of the indicator on each side.
The indicator 24 comprising the hot melt adhesive with wdncss indicator serves the color ottattge function noted above and can also serve to secure the baffle 22 in the diaper 10 relative td the water impervious backing sheet 12 as well as the bther ctimporibnts.
Nowevcr, the baffle 22 does not need to be adhered by an indicator 24 to the backing sheet 12; the absorbent core 1G is secured to the backing sheet 12, as by adhesive lines 3~ and the baffle 22 could be held captive between the backing sheet 12 and the abstirbtnt core 1G.
As previously noted, the overlapping, free edge portiotrs 32 of the baffle 22 are trot adhered to the backing sheet 12 so that liquid can travel from the absorbent core 16, between the baffle 22 and the backing sheet 12 and reach the indicator 24.
In accordance with the invention, the diaper components just described cooperate to determine, for a given diaper, the threshold ~vel of liquid which will be effective tv change *Trade-mark to W~ 94/10958 ~ ~ ~ ~ ~ ~ ~ . ~ P~.'T/US93110890 ~~:i~;":
l;a.~.~.
the indicator 24. It will be appreciated that there is a wide range of thresholds which arc encompassed by the broader aspects of the present invention. The threshold volume can be affected by controlling:
- the degree of overlap of the free edges of the baffle;
- the identity and shape of the particular indicator;
- the identity and quantity of the super absorbent;
- details of construction of the absorbent component; and - the amount and type of fluff, or the like, in the absorbent core.
Generally speaking, increasing the amount of overlap of the baffle 22 will increase the threshold level while decreasing the am~unt of overlap has the og~osite effect. The threshold could he increased by incorporating a particularly fast super absorbent in the absorbent core.
As previously indicated, it is preferred, in a diaper according to the present invention; to have a threshold of at least 20% of the ire-situ capacity of the super absorbent in the diaper.
A 30% threshold is rriore preferred while 40% is still more preferred. It will be appreciated that a threshold approaching or even exceeding the in-situ capacity of the super absorbent component could be operable in a diaper according to the present invention.
Since the absorbent core of a diaper according to the invention includes another absorbent component;
such as fluff, a capacity monitor could be incorporated in a diaper according to the invention having a threshold exceeding the in-situ capacity of the supea absorbent if, for example; ehe fluff component could handle the excess volume of liqui8: lZcgardlcss of the threshold value of a particular combination of diaper and monitor, if the threshoid is exceeded, liquid will reach some portion of the indicator.
Prior art diapers which include super absorbent and fluff and further include hot melt adhesives with wetness indicators; do not have baffles corresponding with the baffle 24.
Consequently, these diapers ha a minuscule thresholds of 5; 1U or 15 milliliters of synthetic urine: A quantity of liquid in excess of these minor thresholds will effect a change in the wetness indicators in the hot melt adhesive, indicating the need for a diaper change, even if the vast majority of the in-situ capacity of super absorbent material in the diapers is unused. It-is estimated hat the threshpld of such prior art diapers is less than 5°l0 of the in-situ capacity of super absorbent in the diapers. In contrast, a capacity monitor in a diaper according to the present invention has a threshold of at least 20% of the in-situ capacity of super absorbent in the diaper,' although 30 to 40%- thresholds are preferred:
EXAIvf Pi,ES l and 2 11' WO 94/10958 .. PGT/US93/10890 ,.. :.~.
Some medium SlimLinc diapers were produced but were modified to include capacity ,;
monitors according to the invention. liz~all of the diapers tested, the indicator was a ribbon, approximately one quarter inch wide and one mil thick, of NICOL-MELT 82525 hot melt adhesive with' wetness indicator. The baffles wart made of paper which had been treated/coated to make it impervious to liquid: The baffles were one and one half inch wide.
Indica was printed on the baffle paper and was visible through; the indicator and the water impervious backing sheet: The indicia comprised the word "KOMFORT" in ,a repeating pattern extending down the center of the diaper, as indicated by the reference numeral 40.
Tie letters were sized and positioned so that each word was four and one half inches tong.
14 The diapers had absorbent cores comprising 12 grams of Aridall super absorbent dispersed in ?0 grams of cellulose fluff.
One such diaper was tested by depositing in it 0.9°l0 NaCL solution at a rate of 7 milliliters per second, in 4U milliliter increments with a final increment of 45 milliliters. The increments were timed to be at least ten minutes apart and, ten minutes after each 40 milliliter deposit, the indicator 24 was observed for evidence of a change in color. The results of this test are set forth below:
EXAMPLE Total Volurcae of Description of color change 0:9!a NaCI incrementally deposited on diaper (milliliters) t 40 no color change 1 80 no color change '20: 1 120 no color change ~
1 160 color change in 1/2 inch length'af indicator 1, ~~ color change in three 1/2 inch lengths of the indicator 1 240 color change in three 1/2 inchlengths of the indicator I X85 color'change in four 1/2 inch tengths of the indicator Seven diapers produced as-described above were sizrtilariy tested except that the 0.9l0 NaCI seven different quantities solution on seven was deposited at a controlled rate in WO 94/10958 2 ~ ~ ~ ~ ~ ~ P'CT/liJS93/10890 ~~~Sx'.' . .. -.
different diapers. The results are set forth below:
EXAMPLE Total Volume of Dcscziption of color change 0,9%
NaCI deposited on diapers (milliliters) 2a 40 no color change 2b 80 no color change 2c '12p no 'color change 2d 160 color change in twa areas;
about 1 inch length, each ,i IOU color change in three ,areas, about l inch in length, each 2f 2.~0 color change in three areas, about 1 inch in length, each z0 12g 285 color change in trvo areas.
about l inch in length, each These tests dernonstratc that the threshold of the capacity monitor which in the modified medium SlimLina diaper was -between 120 and 160 milliliters, regardless of whether liquid was applied all at once or in spaced apart intervals.
With one exception;
these tests indicate that;
once the threshold was exceeded, there was a color change in a portion of the indicator and he length of the affected portion was proportionate to the volume of liquid which exceeded the threshold.
In a diaper according to the invention, having a threshold which is significantly below the in-situ capacity of the super absorbent, indicia such as 40;
having a predetermined icngth can be combined with the monitor so as to provide an indication of the remaining in-situ capacity (or othcx measure of capacity) when the threshold is exceeded:
With reference to Fig.
2, the length of the repeating' indicia ~0 has been predetermined relative to a particular capacity of a diaper corresponding with Examples and 2a-2g.
The length of the indicia 4t? was based upon the capacity of the diaper to retain synthetic urine with skin wetness of 0.0 after ten minutes which:
as shown in Fig:
1, is about 285 milliliters.
With a threshold, of between 120 and 160 milliliters, exhaustion of the remaining capacity of the diaper (approximately 140 millitifcrs) will be associated with a color change in the indicator over approximatelyfour and one half inches of its length:
The indicia 40 provide a convenient measure of this length as well as a convenient way to ascertain, far example when substantially Icss than four and one half inches of the indicator WO 94/10958 ' . ' ' PC>f/US93/10890 ~~'.°
w~:d~
has chanced color, that the diaper still has substantial capacity to absorb additional synthetic urine and exhibit, ten minutes after the synthetic urine is deposited, skin wetness of U.U.
It has been determined that the hot melt adhesive with wetness indicator 24 (Fig. 3) can stick to the backing sheet 1? to such an extent that it prevents a change from occurring in the indicator ?4, even when liquid in an amount excceciing the threshold amount is absorbed in the absorbent core. Thisproblem is exacerbated by heat. It has further been determined that problems associated with sticking between the indicator 24 and the backing sheet I2 can be overcome in a prcf~rred embodiment of the present invention which is described below with reference to Figs. :l and 5 In a preferred embodiment, a comfort monitor indicated generally at 20' (Figs.
~ and 5) includes a strip of non-woven material 42-positioned between the backing sheet.12 and the indicator ?4: Preferably, as shown in Fig. 5, the width of the non-woven strip ~42 is less than the width of the baffle 3, but is greater than the width of the indicator strip 24. Non-woven material is generally hydrophobic, rncaning that it repels water and other liquids. In accordance with the preferred embodiment of the present invention, the non-woven strip 42 is treated with a surfactant (not shown) to make it hydrophilic. As a consequence, the rested non-woven strip can transmit liquid, when available, into contact with the indicator 2~ to effect a color change in the indicator. This construction has been found to preserve the threshold properties discussed above; while ensuring that liquid; in an amount exceeding the threshold; will reach the indicator 24 and effect a changs~ in it. Further;
the strategic use of a hydrophilic strip of .non-woven; or the like, as described above; prevents the indicator;.
when exposed to high tempcxatures; from sticking to the backing sheet l2 to such an extent that the monitor is rendered inoperable.
'f'he . foregoing description is infcndcd to enable those skilled in the art to practice the present invention and con5titutcs the best mode presently known for practicing the invention.
For example, although the invention has been described in the context, of a diaper product, it will be appreciated that the invention has broader application to the field of products having an absorbent corn including super absorbent polymer with a capacity moriieor for indicating when' a threshold amount of liquid has been absorbed in the core.
Undoubtedly, modifications will occur to those skilled in the art, and such modifications may b~ resorted to without departing from the spirit and scope of fhe invention disclosed herein and claimed ;
below.
solution to be absorbed out of the fluff into the super absorbent, that quantity of 0.996 NaCI solution in the fluff would trigger a color .
change in conventionally applied hot melt adhesives with wetness ~ indicators.
While this phenomenon might increase salts of SIimLinc diapers and other products incorporating conventionally applied hot melt adhesives with wetness indicators, it would also unneocssarily increase the bucdcn on already overburdened landfills as well as the burden on care givers who tend to the changing of absorbent products used by persons with urinary incontinence. So, there is demonstrated a steed for a capacity monitor which is capable of providing a reliable indication of when the in-situ capacity of super absorbent material has been exceeded, without providing a premature indication. such as when there is substantial remaining in-situ capacity in the super absorbent.
I I, , ',', ~II . 61 SUi~ARY OF THE INVENTION
According to one aspect of the present invention, there is provided a diaper including a capacity monitor, said diaper comprising an absorbent core including super absorbent material, a hydrophilic cover sheet and a water impervious, translucent or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper having a given in-situ capacity for synthetic urine, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said diaper adjacent to said backing sheet so that the change of the indicator is visually perceptible through said sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which synthetic urine can migrate from said absorbent core to said indicator, said baffle being operable to prevent the flow of synthetic urine into wetting relationship with said indicator when the diaper contains an amount of synthetic urine which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the diaper contains an amount of synthetic urine which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
According to another aspect of the present invention, there is provided a diaper including a capacity monitor, said diaper comprising an absorbent core comprising 6a i, a fluff component and a super absorbent component, a hydrophilic cover sheet and a water impervious, translucent or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper having a given in-situ capacity for synthetic urine, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said diaper adjacent to said backing sheet so that the change of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which synthetic urine can migrate from said absorbent core to said indicator, said baffle being effective, in cooperation with the components of the diaper, to prevent the flow of synthetic urine into wetting relationship with said indicator when the diaper contains an amount of synthetic urine which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the diaper contains an amount of synthetic urine which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
According to still another aspect of the present invention, there is provided a diaper including a capacity monitor, said diaper comprising an absorbent core including a fluff component and a super absorbent component, a hydrophilic cover sheet and a water impervious, translucent 6b i , or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper being operable to absorb up to a given, maximum quantity of a desired liquid to the extent that, ten minutes after deposition of said given amount of liquid, said diaper has a skin wetness number of substantially zero, said capacity monitor comprising a hot melt adhesive containing a color change indicator, and extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible color change when said hot melt adhesive is wet, said hot melt adhesive being positioned in said diaper adjacent to said backing sheet so that the change of color of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said hot melt adhesive and separate it from said absorbent core, said baffle having a width which is greater than that of said hot melt adhesive and a free edge around which liquid can migrate from said absorbent core to said hot melt adhesive, said baffle cooperating with the components of the diaper to control the migration of liquid from said at least one absorbent component to said indicator so that said given quantity of desired liquid deposited on the diaper produces a visually perceptible change over a predetermined length of said indicator and indicia provided on said diaper and visible through said backing sheet, said indicia being operable to indicate the predetermined length of said hot melt adhesive which undergoes a visually perceptible change when said given quantity of desired liquid is deposited on the diaper.
6c i , ~~
According to yet another aspect of the present invention, there is provided an absorbent product including a capacity monitor, said product comprising an absorbent core including super absorbent material, said core having a first and a second side, and a water impervious, translucent or transparent backing sheet, said backing sheet being positioned adjacent to said first side of said core and said super absorbent material in said absorbent product having a given in-situ capacity for liquid, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said absorbent product between said backing sheet and said core so that the change of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which liquid can migrate from said absorbent core to said indicator, said baffle being operable to prevent the flow of a liquid into wetting relationship with said indicator when the core contains an amount of the liquid which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the core contains an amount of the liquid which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
The instant invention is based upon the discovery of a capacity monitor which is operable to provide a visible signal when the in-situ capacity of super absorbent material in a given absorbent core has been, or is close to being, 6d I i. . ii exceeded by liquid absorbed in the absorbent core. In a diaper comprising a water impervious backing sheet and an absorbent core comprising fluff and super absorbent material, the monitor comprises an indicator, such as a hot melt adhesive with a wetness indicator between the absorbent core and the backing 6e 2~.~~3~a WO 94!10958 ' PGT/US93/10890 ,:~i~,.
~:, . .
sheet. The monitor further comprises a substantially water impervious baffle positioned between the absorbent core and the hot melt adhesive, to prevent substantial contact between the indicator and liquid contained in the absorbent core, except when the quantity of such liquid exceeds a predetermined threshold volume of liquid: The monitor may further comprise a strip of non-woven material, or the like, positioned between the indicator and the backing sheet to prevent sticking therebetween: When a quantity of liquid which exceeds the threshold volume of liquid is deposited in the diaper, some of the liquid will migrate around the baffh and trigger a color change or the like in the indicator. The threshold level -is predetermined, for a given diaper, relative to the in--situ eapacity of-the super absorbent !U material in the absorbent core of the diaper: Preferably, the threshold volume is at least 20%
of the in-situ capacity of the super absorbent. More preferably, the threshold is at !cast 3U%
of the in-situ capacity while 4U% is mare preferred still. In some cases, the threshold may approach or even exceed the in-situ capacity' of the super absorbent in the absorbent core, if the other absorbent material therein is adequate to 'take up the slack. 'W
hen a strip of non-woven material, or the like, is proyidcd between the indicator and the backing sheet, it facilitates the transfer of liquid from the core to the indicator so that a change in the indicator occurs reliably when the threshold amount is exeeedec3; thereby overcoming any tendency of the indicator to stick to the backing shoes and prevent a change in the indicator.
Iri cases where the threshold is substantially below the in-situ capacity of the . super absorbent; the monitor may further;comprisc printed i'~dicia which provides a visually discernible signal which, together with the degree or extent or length indicator which changes color or the like, provides an indication of the remaining in-situ capacity, if any, of the super absorbent material in the absorbent core.
FIG. 1 is plot of elapsed time before a prior art diaper including super absorbent material achieves a zero skin wetness number: versus quantity of liquid deposited in the diaper.
FIG. 2 plan view, partially broken away, of a diaper incorporating a capacity monitor according to the present invention.
FTG. 3 is a crass sectional view, taken along the lines 3 - 3 of Fig. 2, showing some details of the capacity monitor according to fhc present invention.
'1~0 94/k09S8 . ~ PCT/US93/10890 FIG. 4 plan view, partially broken away, of .. ~; :preferred embodiment of a diaper incorporating a capacity monitor according to~ the pi~esent invention.
FIG. 5 is,a cross sectional view, taken along the lines 5 - 5 of Fig. 4, showing some details of a preferred capacity monitor according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to Fig. 2, a disposable diaper is indicated generally at 10. The diaper 10 comprises a water impervious backing shcef 13, a non--woven facing sheet 14 which would contact a wearer's skin when the diaper 1U is in use and an absorbent core 16.
In acebrdance with the invention, the absorbent core has at least two absorbent 'components, which are illustrated in and discussed below in connection with Fig. 3. Specifically, the core 16 has an absorbent fluff component and -a Super absorbent cotttponent. In accordance with the present invention, the super absorbent may be incorporated into the absorbent core in ariy suitable manner including those disclosed in said US Patent No. 5,072,687. The patent discloses the deposition of particulate super absorbent into a fluff Layer or ball. Also disclosed is a construction wherein super absorbent is contained in a laminate, i.e., one of more sheets of tissue with super absorbent adhered to and supported thereon, and the laminate is incorporated in an absorbent core. A combination of these constructions is also disclosed where loose super absorbent particles arid laminate containing super absorbent are combined with an absorbent cellulose fluff ball. lfic~e components of diaper IO are .
conventional and are well known in the industry.
A portion of the water impervious backing sheet 12 has been cut away in Fig. 2 to illustrate a capacity monitor; according to the present invention, indicated generally at 20.
The monitor 20 comprises a baffle 22 which extends along the longitudinal centerline of the diaper 10 and an indicator 24 which'undergoes a visually perceptible change when wetted.
The indicator 24 is positioned between the backing sheet I?. and the absorbent core 16. The baftlc 22, in turn; is positioned between the absorbent core 1G and the indicator 24. The baffle 2,2 is operable to prevent contact between liquid held in the absorbent Gore 16 and the indicator 24. Tlte rnonitar 20 is constructed, however; so that when there is quantity of liquid in the absorbent core which approaches or exceeds the in-situ capacity of he super absorbent in the absorbent core, the some of the liquid will contact the inditratar 24 effecting a perceptible change in it. Further details of construction for the digger i0 as well as the capacity monitor 20 arc discussed below with reference to °Fig. 3.
~..i;'1i9 ;..Y WO 94/)10958 ~ ~ ~ ~ ~ ~ ~ . .. ~ : PCT/US93/10890 '~ :; J
The baffle 23 may comprises a sheet of polymeric, water impervious film or paper which has been treated ox coated to render it water impervious or substantially so. The baffle 22 is positioned between the absorbent core l6 and the water impervious backing sheet 12.
The core 16, as previously irxdicated, includes a fluff component 26 and a super absorbent component which, in the illustrated embodiment, comprises discreet particles of super absorbent 28 carried in the fluff 26. A layer of tissue 30 is positioned between the fluff 26 and the non-woven facing sheet 14. As disclosed in US Patent No. 5,072,687, a layer of laminate (not shown) may bG setbstitutcd for the tissue layer 30, or combined with it and positioned between the fluff layer 2G and the tissue Iaycr 30; The monitor 20 further comprises the indicator 24 which is positioned between the baffle 23 and the water impervious backing sheet 12, The baffle 2? physically separates the fluff layer 26 and the absorbent core 1 G from the indicator 24 so than there is no direct contact between the indicator 24 and the fluff layer 26 or the absorbent core 1G.
The baffle 22 is comprised, at leash in part, of a hydrophobic material so that it constitutes a .physical barrier to the flow of liquid from the fluff layer 26 through the baffle 22 to he indicator 24. With the baffle ?2 in place, liquid in the fluff layer 26 can reach the indicator 24 only if it travels around free edges 32 of the baffle and travels between the baffle 2? and the water impervious backing sheet 12 to reach the indicator 24.
So long as the volume of Liquid in the diaper is such that the liquid can be held tightly or fairly tightly in the absorbent components of the'absorbent core 16, the liquid will not reach the indicator.
When the volume of Liquid in the diaper exceeds the volume which the absorbent components of the core 16 can hold fairly ightiy; there will be excess Liquid in the diaper IO such as would tend to pooh or puddle adjacent to or on the surface of the backing sheet I2 near the baffle 22 and some of it would travel around the free edges 32 of the baffle 22 and teach the indicator. In other words, there is a threshold level of liquid which must be deposited on the absorbent core in order for any liquid to reach the indicator. Thus, the movement of liquid from the absorbent core 16 to the indicator 24 is enabled when there is enottglz liquid. The edges 32 of the baffle 22 are free edges in the sense that they are not adhered to he backing sheet 12. Care must be taken, in producing a diaper with a capacity monitor 20 according to the invention in case the diaper includes conventional lines of hot melt adhesive without a wetness indicator 33 to adhere the absorbent core 16 to the backing sheet''12. Such adhesive Lines 33 must-not completely adhere the free edges 32 of the baffle ?? to the backing sheet 12, or vice versa. Instead, the hot melt adhesive lines 33 would be positioned, as shown in Fig. 3, where they do not engage the free edges 32 of the bafflc'22.
The indicator 24 preferably comprises a hot melt adhesive with a wetness indicator. A
preferred iridicator material is NICOL-MELT 82525 'which is available ttuough Swift Adhesives or its parent Reichhotd Chemical. This particular hot melt material is translucent and has a yellow color when it is allied, for example, to the baffle, ?.?. or the water impervious backing sheet i2. In the illustrated embodiment, it is preferred that the indicator consist of a ribbon of the indicated hot melt adhesive with wetness indicator having a width of approximately one quarter to one half inch (0.5 to 1.5 centimeters) and a thickness of l0 about one mil (0.035 millimeter). Insofar as the operability of th'te~~present invention is ~r:~.
concerned, the indicator may be applied either to the backing sheet 13 or the baffle 22.
Upon contacting most liquids, including synthetic and non-synthetic urine, the NICOL-MELT will change color, at the contact areas, from a tight or faint translucent yellow to a relatively dark and deep blue. This color change is readily pcroeivable through the water impervious cover 12 which, as previously mcntioried, is transparent of translucent.
The baffle 22 has a width which exceeds the width of the indicator 24.
Consequently, free edge portions 32 of the baftlc ?3 overlap edges 34 of the indicator 24, thereby hindering liquid in the absorbent core 16 from traveling to the indicator 24.
Good results have been obtained with a coated paper baffle having a width of approximately bnc and one quarter inches (3 centimeters) and an indicator.having a width of about vne quartet inch, so that at (cast one half inch (1 ~5 centimeters) of the baffle overlapped the edge of the indicator on each side.
The indicator 24 comprising the hot melt adhesive with wdncss indicator serves the color ottattge function noted above and can also serve to secure the baffle 22 in the diaper 10 relative td the water impervious backing sheet 12 as well as the bther ctimporibnts.
Nowevcr, the baffle 22 does not need to be adhered by an indicator 24 to the backing sheet 12; the absorbent core 1G is secured to the backing sheet 12, as by adhesive lines 3~ and the baffle 22 could be held captive between the backing sheet 12 and the abstirbtnt core 1G.
As previously noted, the overlapping, free edge portiotrs 32 of the baffle 22 are trot adhered to the backing sheet 12 so that liquid can travel from the absorbent core 16, between the baffle 22 and the backing sheet 12 and reach the indicator 24.
In accordance with the invention, the diaper components just described cooperate to determine, for a given diaper, the threshold ~vel of liquid which will be effective tv change *Trade-mark to W~ 94/10958 ~ ~ ~ ~ ~ ~ ~ . ~ P~.'T/US93110890 ~~:i~;":
l;a.~.~.
the indicator 24. It will be appreciated that there is a wide range of thresholds which arc encompassed by the broader aspects of the present invention. The threshold volume can be affected by controlling:
- the degree of overlap of the free edges of the baffle;
- the identity and shape of the particular indicator;
- the identity and quantity of the super absorbent;
- details of construction of the absorbent component; and - the amount and type of fluff, or the like, in the absorbent core.
Generally speaking, increasing the amount of overlap of the baffle 22 will increase the threshold level while decreasing the am~unt of overlap has the og~osite effect. The threshold could he increased by incorporating a particularly fast super absorbent in the absorbent core.
As previously indicated, it is preferred, in a diaper according to the present invention; to have a threshold of at least 20% of the ire-situ capacity of the super absorbent in the diaper.
A 30% threshold is rriore preferred while 40% is still more preferred. It will be appreciated that a threshold approaching or even exceeding the in-situ capacity of the super absorbent component could be operable in a diaper according to the present invention.
Since the absorbent core of a diaper according to the invention includes another absorbent component;
such as fluff, a capacity monitor could be incorporated in a diaper according to the invention having a threshold exceeding the in-situ capacity of the supea absorbent if, for example; ehe fluff component could handle the excess volume of liqui8: lZcgardlcss of the threshold value of a particular combination of diaper and monitor, if the threshoid is exceeded, liquid will reach some portion of the indicator.
Prior art diapers which include super absorbent and fluff and further include hot melt adhesives with wetness indicators; do not have baffles corresponding with the baffle 24.
Consequently, these diapers ha a minuscule thresholds of 5; 1U or 15 milliliters of synthetic urine: A quantity of liquid in excess of these minor thresholds will effect a change in the wetness indicators in the hot melt adhesive, indicating the need for a diaper change, even if the vast majority of the in-situ capacity of super absorbent material in the diapers is unused. It-is estimated hat the threshpld of such prior art diapers is less than 5°l0 of the in-situ capacity of super absorbent in the diapers. In contrast, a capacity monitor in a diaper according to the present invention has a threshold of at least 20% of the in-situ capacity of super absorbent in the diaper,' although 30 to 40%- thresholds are preferred:
EXAIvf Pi,ES l and 2 11' WO 94/10958 .. PGT/US93/10890 ,.. :.~.
Some medium SlimLinc diapers were produced but were modified to include capacity ,;
monitors according to the invention. liz~all of the diapers tested, the indicator was a ribbon, approximately one quarter inch wide and one mil thick, of NICOL-MELT 82525 hot melt adhesive with' wetness indicator. The baffles wart made of paper which had been treated/coated to make it impervious to liquid: The baffles were one and one half inch wide.
Indica was printed on the baffle paper and was visible through; the indicator and the water impervious backing sheet: The indicia comprised the word "KOMFORT" in ,a repeating pattern extending down the center of the diaper, as indicated by the reference numeral 40.
Tie letters were sized and positioned so that each word was four and one half inches tong.
14 The diapers had absorbent cores comprising 12 grams of Aridall super absorbent dispersed in ?0 grams of cellulose fluff.
One such diaper was tested by depositing in it 0.9°l0 NaCL solution at a rate of 7 milliliters per second, in 4U milliliter increments with a final increment of 45 milliliters. The increments were timed to be at least ten minutes apart and, ten minutes after each 40 milliliter deposit, the indicator 24 was observed for evidence of a change in color. The results of this test are set forth below:
EXAMPLE Total Volurcae of Description of color change 0:9!a NaCI incrementally deposited on diaper (milliliters) t 40 no color change 1 80 no color change '20: 1 120 no color change ~
1 160 color change in 1/2 inch length'af indicator 1, ~~ color change in three 1/2 inch lengths of the indicator 1 240 color change in three 1/2 inchlengths of the indicator I X85 color'change in four 1/2 inch tengths of the indicator Seven diapers produced as-described above were sizrtilariy tested except that the 0.9l0 NaCI seven different quantities solution on seven was deposited at a controlled rate in WO 94/10958 2 ~ ~ ~ ~ ~ ~ P'CT/liJS93/10890 ~~~Sx'.' . .. -.
different diapers. The results are set forth below:
EXAMPLE Total Volume of Dcscziption of color change 0,9%
NaCI deposited on diapers (milliliters) 2a 40 no color change 2b 80 no color change 2c '12p no 'color change 2d 160 color change in twa areas;
about 1 inch length, each ,i IOU color change in three ,areas, about l inch in length, each 2f 2.~0 color change in three areas, about 1 inch in length, each z0 12g 285 color change in trvo areas.
about l inch in length, each These tests dernonstratc that the threshold of the capacity monitor which in the modified medium SlimLina diaper was -between 120 and 160 milliliters, regardless of whether liquid was applied all at once or in spaced apart intervals.
With one exception;
these tests indicate that;
once the threshold was exceeded, there was a color change in a portion of the indicator and he length of the affected portion was proportionate to the volume of liquid which exceeded the threshold.
In a diaper according to the invention, having a threshold which is significantly below the in-situ capacity of the super absorbent, indicia such as 40;
having a predetermined icngth can be combined with the monitor so as to provide an indication of the remaining in-situ capacity (or othcx measure of capacity) when the threshold is exceeded:
With reference to Fig.
2, the length of the repeating' indicia ~0 has been predetermined relative to a particular capacity of a diaper corresponding with Examples and 2a-2g.
The length of the indicia 4t? was based upon the capacity of the diaper to retain synthetic urine with skin wetness of 0.0 after ten minutes which:
as shown in Fig:
1, is about 285 milliliters.
With a threshold, of between 120 and 160 milliliters, exhaustion of the remaining capacity of the diaper (approximately 140 millitifcrs) will be associated with a color change in the indicator over approximatelyfour and one half inches of its length:
The indicia 40 provide a convenient measure of this length as well as a convenient way to ascertain, far example when substantially Icss than four and one half inches of the indicator WO 94/10958 ' . ' ' PC>f/US93/10890 ~~'.°
w~:d~
has chanced color, that the diaper still has substantial capacity to absorb additional synthetic urine and exhibit, ten minutes after the synthetic urine is deposited, skin wetness of U.U.
It has been determined that the hot melt adhesive with wetness indicator 24 (Fig. 3) can stick to the backing sheet 1? to such an extent that it prevents a change from occurring in the indicator ?4, even when liquid in an amount excceciing the threshold amount is absorbed in the absorbent core. Thisproblem is exacerbated by heat. It has further been determined that problems associated with sticking between the indicator 24 and the backing sheet I2 can be overcome in a prcf~rred embodiment of the present invention which is described below with reference to Figs. :l and 5 In a preferred embodiment, a comfort monitor indicated generally at 20' (Figs.
~ and 5) includes a strip of non-woven material 42-positioned between the backing sheet.12 and the indicator ?4: Preferably, as shown in Fig. 5, the width of the non-woven strip ~42 is less than the width of the baffle 3, but is greater than the width of the indicator strip 24. Non-woven material is generally hydrophobic, rncaning that it repels water and other liquids. In accordance with the preferred embodiment of the present invention, the non-woven strip 42 is treated with a surfactant (not shown) to make it hydrophilic. As a consequence, the rested non-woven strip can transmit liquid, when available, into contact with the indicator 2~ to effect a color change in the indicator. This construction has been found to preserve the threshold properties discussed above; while ensuring that liquid; in an amount exceeding the threshold; will reach the indicator 24 and effect a changs~ in it. Further;
the strategic use of a hydrophilic strip of .non-woven; or the like, as described above; prevents the indicator;.
when exposed to high tempcxatures; from sticking to the backing sheet l2 to such an extent that the monitor is rendered inoperable.
'f'he . foregoing description is infcndcd to enable those skilled in the art to practice the present invention and con5titutcs the best mode presently known for practicing the invention.
For example, although the invention has been described in the context, of a diaper product, it will be appreciated that the invention has broader application to the field of products having an absorbent corn including super absorbent polymer with a capacity moriieor for indicating when' a threshold amount of liquid has been absorbed in the core.
Undoubtedly, modifications will occur to those skilled in the art, and such modifications may b~ resorted to without departing from the spirit and scope of fhe invention disclosed herein and claimed ;
below.
Claims (12)
1. A diaper including a capacity monitor, said diaper comprising an absorbent core including super absorbent material, a hydrophilic cover sheet and a water impervious, translucent or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper having a given in-situ capacity for synthetic urine, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said diaper adjacent to said backing sheet so that the change of the indicator is visually perceptible through said sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which synthetic urine can migrate from said absorbent core to said indicator, said baffle being operable to prevent the flow of synthetic urine into wetting relationship with said indicator when the diaper contains an amount of synthetic urine which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the diaper contains an amount of synthetic urine which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
2. The diaper claimed in claim 1 which additionally includes indicia provided on said diaper and visible through said backing sheet, said indicia being operable to indicate a predetermined length of said indicator which undergoes a visually perceptible change when a quantity of synthetic urine approximately equal to the in-situ capacity of the super absorbent has been deposited on the diaper.
3. The diaper claimed in claim 1 or 2 wherein the given percent is at least thirty percent of the in-situ capacity of the super absorbent in the diaper.
4. The diaper claimed in claim 1 or 2 wherein the given percent is at least forty percent of the in-situ capacity of the super absorbent in the diaper.
5. A diaper including a capacity monitor, said diaper comprising an absorbent core comprising a fluff component and a super absorbent component, a hydrophilic cover sheet and a water impervious, translucent or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper having a given in-situ capacity for synthetic urine, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said diaper adjacent to said backing sheet so that the change of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which synthetic urine can migrate from said absorbent core to said indicator, said baffle being effective, in cooperation with the components of the diaper, to prevent the flow of synthetic urine into wetting relationship with said indicator when the diaper contains an amount of synthetic urine which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the diaper contains an amount of synthetic urine which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
6. The diaper claimed in claim 5 which additionally includes indicia provided on said diaper and visible through said backing sheet, said indicia being operable to indicate a predetermined length of said indicator which undergoes a visually perceptible change when a quantity of synthetic urine approximately equal to the in-situ capacity of the super absorbent has been deposited on the diaper.
7. The diaper claimed in claim 5 or 6 wherein the given percent is at least thirty percent of the in-situ capacity of the super absorbent in the diaper.
8. The diaper claimed in claim 5 or 6 wherein the given percent is at least forty percent of the in-situ capacity of the super absorbent in the diaper.
9. A diaper including a capacity monitor, said diaper comprising an absorbent core including a fluff component and a super absorbent component, a hydrophilic cover sheet and a water impervious, translucent or transparent backing sheet, said core being positioned between said cover sheet and said backing sheet and said super absorbent material in said diaper being operable to absorb up to a given, maximum quantity of a desired liquid to the extent that, ten minutes after deposition of said given amount of liquid, said diaper has a skin wetness number of substantially zero, said capacity monitor comprising a hot melt adhesive containing a color change indicator, and extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible color change when said hot melt adhesive is wet, said hot melt adhesive being positioned in said diaper adjacent to said backing sheet so that the change of color of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said hot melt adhesive and separate it from said absorbent core, said baffle having a width which is greater than that of said hot melt adhesive and a free edge around which liquid can migrate from said absorbent core to said hot melt adhesive, said baffle cooperating with the components of the diaper to control the migration of liquid from said at least one absorbent component to said indicator so that said given quantity of desired liquid deposited on the diaper produces a visually perceptible change over a predetermined length of said indicator and indicia provided on said diaper and visible through said backing sheet, said indicia being operable to indicate the predetermined length of said hot melt adhesive which undergoes a visually perceptible change when said given quantity of desired liquid is deposited on the diaper.
10. The diaper claimed in claim 1, 5 or 9 which further comprises a strip of non-woven material positioned between said indicator and said backing sheet, said strip of non-woven material being hydrophilic and being operable to prevent sticking between said indicator and said backing sheet so that synthetic urine is able to migrate from said absorbent core to said indicator.
11. An absorbent product including a capacity monitor, said product comprising an absorbent core including super absorbent material, said core having a first and a second side, and a water impervious, translucent or transparent backing sheet, said backing sheet being positioned adjacent to said first side of said core and said super absorbent material in said absorbent product having a given in-situ capacity for liquid, said capacity monitor comprising an indicator extending longitudinally a substantial distance, said indicator being operable to provide a visually perceptible change when wet, said indicator being positioned in said absorbent product between said backing sheet and said core so that the change of the indicator is visually perceptible through said backing sheet and a substantially water impervious baffle positioned inside the diaper between said backing sheet and said absorbent core so as to cover said indicator and separate it from said absorbent core, said baffle having a width which is greater than that of said indicator and a free edge around which liquid can migrate from said absorbent core to said indicator, said baffle being operable to prevent the flow of a liquid into wetting relationship with said indicator when the core contains an amount of the liquid which is less than a given percent of the in-situ capacity of the super absorbent, and ineffective to prevent such flow when the core contains an amount of the liquid which is greater than the given percent of the in situ capacity of the super absorbent, the given percent being at least 20.
12. The absorbent product claimed in claim 11 which further comprises a strip of non-woven material positioned between said indicator and said backing sheet, said strip of non-woven material being hydrophilic and being operable to prevent sticking between said indicator and said backing sheet so that liquid is able to migrate from said absorbent core to said indicator.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US97583892A | 1992-11-13 | 1992-11-13 | |
| US07/975,838 | 1992-11-13 | ||
| US08/096,552 US5354289A (en) | 1993-07-23 | 1993-07-23 | Absorbent product including super absorbent material and a fluid absorption capacity monitor |
| US08/096,552 | 1993-07-23 | ||
| PCT/US1993/010890 WO1994010958A1 (en) | 1992-11-13 | 1993-11-12 | Absorbent including super absorbent and capacity monitor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2149325A1 CA2149325A1 (en) | 1994-05-26 |
| CA2149325C true CA2149325C (en) | 2003-12-16 |
Family
ID=26791816
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002149325A Expired - Fee Related CA2149325C (en) | 1992-11-13 | 1993-11-12 | Absorbent including super absorbent and capacity monitor |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0727975A1 (en) |
| AU (1) | AU5600194A (en) |
| CA (1) | CA2149325C (en) |
| WO (1) | WO1994010958A1 (en) |
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| FR2733146A1 (en) * | 1995-04-18 | 1996-10-25 | Carriel Jean Claude | Saturation indicator for absorbent material, e.g. baby's nappy |
| JP3533285B2 (en) * | 1996-05-16 | 2004-05-31 | ユニ・チャーム株式会社 | Disposable diapers |
| US5876389A (en) * | 1996-06-24 | 1999-03-02 | Ezy-Detek (Edi) Inc. | Sanitary napkins and method for collecting samples of bodily substances |
| GB2327354A (en) * | 1997-07-21 | 1999-01-27 | Richard Abbott | Disposable nappy with wetness indicator |
| US5902296A (en) * | 1997-09-25 | 1999-05-11 | Fluyeras; Alexandra | Incontinence brief with moisture indicating strip |
| DE19914037A1 (en) * | 1999-03-27 | 2000-09-28 | Hartmann Paul Ag | Disposable hygiene items |
| RU2182476C1 (en) * | 2001-07-12 | 2002-05-20 | Достойнов Илья Андреевич | Sanitary and hygienic means and method for determining organism state |
| US6719691B2 (en) | 2001-07-26 | 2004-04-13 | Common Sense Ltd. | Method, device and kit for obtaining biological samples |
| JP4677597B2 (en) | 2001-08-31 | 2011-04-27 | ユニ・チャーム株式会社 | Disposable diapers |
| US7615040B2 (en) | 2001-12-19 | 2009-11-10 | Kimberly-Clark Worldwide, Inc. | Thin, flexible, low capacity absorbent article with leakage protection |
| US7322472B2 (en) * | 2002-09-20 | 2008-01-29 | Kimberly-Clark Worldwide, Inc. | Void volume indicator and method of consumer product selection |
| US7285160B2 (en) | 2003-11-04 | 2007-10-23 | Videojet Technologies Inc. | Ink jet ink composition for wetness indication |
| GB2408204B (en) * | 2003-11-21 | 2005-11-23 | Ucl Biomedica Plc | Mattress protection |
| US8222476B2 (en) | 2008-10-31 | 2012-07-17 | Kimberly-Clark Worldwide, Inc. | Absorbent articles with impending leakage sensors |
| WO2015143282A1 (en) | 2014-03-20 | 2015-09-24 | The Procter & Gamble Company | Volume indicators with masking layer |
| ES2901215T3 (en) | 2016-05-27 | 2022-03-21 | Aadigen Llc | Peptides and nanoparticles for intracellular delivery of genome editing molecules |
| KR102637960B1 (en) | 2017-04-22 | 2024-02-21 | 이뮤노믹 쎄라퓨틱스, 인크. | Improved LAMP construct |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2681032A (en) * | 1953-05-21 | 1954-06-15 | Joseph D Shaw | Accessory for infants' diapers |
| DE2031104A1 (en) * | 1970-06-24 | 1971-12-30 | Sievers, Hans-Joachim, 2000 Hamburg | Disposable baby's nappy - with wet indicator to prevent nappy rash |
| US4231370A (en) * | 1979-06-18 | 1980-11-04 | The Procter & Gamble Company | Disposable diaper type garment having wetness indicator |
| US4507121A (en) * | 1983-05-02 | 1985-03-26 | Leung Martin C | Disposable diaper with isolated wetness indicator |
| US4743238A (en) * | 1986-03-17 | 1988-05-10 | Malcolm Nicol & Co. | Wetness indicating hot-melt adhesives |
| US4834733A (en) * | 1987-11-12 | 1989-05-30 | Kimberly-Clark Corporation | Fluid activated mechanical absorbency gauge |
-
1993
- 1993-11-12 EP EP94901403A patent/EP0727975A1/en not_active Withdrawn
- 1993-11-12 AU AU56001/94A patent/AU5600194A/en not_active Abandoned
- 1993-11-12 CA CA002149325A patent/CA2149325C/en not_active Expired - Fee Related
- 1993-11-12 WO PCT/US1993/010890 patent/WO1994010958A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| CA2149325A1 (en) | 1994-05-26 |
| AU5600194A (en) | 1994-06-08 |
| EP0727975A4 (en) | 1996-09-11 |
| WO1994010958A1 (en) | 1994-05-26 |
| EP0727975A1 (en) | 1996-08-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20131113 |