CA2158790A1 - Perimeter barrier seal for personal care absorbent articles and the like - Google Patents
Perimeter barrier seal for personal care absorbent articles and the likeInfo
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- CA2158790A1 CA2158790A1 CA 2158790 CA2158790A CA2158790A1 CA 2158790 A1 CA2158790 A1 CA 2158790A1 CA 2158790 CA2158790 CA 2158790 CA 2158790 A CA2158790 A CA 2158790A CA 2158790 A1 CA2158790 A1 CA 2158790A1
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- laminate
- elastic
- personal care
- high loft
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Abstract
Disclosed herein is a perimeter barrier seal for, among other things, personal care absorbent articles such as diapers, training pants, incontinence garments, sanitary napkins, bandages and the like. The seal includes a high loft nonwoven web facing layer desirably made from multicomponent or multiconstituent fibers which are highly crimped and through-air bonded to one another. The seal also includes an elastic layer and, optionally, a backing layer.
Description
PERIMETER BARRIER SEAL FOR PERSONAL CARE ABSORBENT
ARTICLES AND THE LIKE
FIELD OF THE INVENTION
The present invention is directed to a perimeter barrier seal material. More particularly, the present invention is directed to a perimeter barrier seal material which is suitable for use as a gasketing means which can be used about the periphery of such personal care absorbent articles as, for example, diapers to reduce leakage of liquids about the leg and/or waist openings of the article.
BACKGROUND OF THE INVENTION
The primary purpose of personal care absorbent articles such as diapers, training pants, incontinence garments, sanitary napkins, bandages and the like is to absorb and retain exudated body fluids. Rapid up-take of liquids such as urine has been a long standing problem in the design of such personal care absorbent articles, especially with respect to such articles as diapers, training pants and incontinence garments.
Such factors as article design, the speed and/or amount of the delivered insult and repeated insults oftentimes result in a quantity of liquid which cannot be quickly absorbed into the article. The natural tendancy of the nonabsorbed liquid is to flow across the interior surface of the article and exit the article wherever possible. For full body fitting articles such as diapers, incontinence garments and training pants, the primary place for escape is around the leg openings and, 21~7~
secondarily, around the waist opening. Consequently, if the article cannot handle the insult, the liquid or other body waste material will try to exit one of these openings.
In an attempt to stem the flow of liquid ou,t the leg openings in such personal care absorbent articles, diapers were first fitted with leg elastic about the leg openings. Next, the diapers were fitted with leg flaps which were installed on the interior surface of the diapers inboard of the leg elastics. The same types of leg flaps are now being employed in training pants to also further retard leakage. Such leg flaps are usually made from thin elasticized strips of material which extend upwardly from the plane of the diaper approximately 3 centimeters (cm~ and which are typically about 0.5 to about O.g millimeters (mm) thick. During use, such leg flaps typically are folded over and lay rather flat against the torso of the wearer.
While the leg openings are the most common area for leakage from personal care absorbent articles such as diapers, training pants and incontinence garments, it is also possible to experience leakage about the waistband of such articles. In an attempt to reduce leakage in this area, it is now not an uncommon practice to employ elastic in all or a part of the waistband region of the article so as to increase the tensional fit of the garment against the torso of the wearer. Here again, such designs have been met with varying degrees of success.
It is an aspect of the present invention to provide a perimeter barrier seal which can be used as a gasket about all or a portion of such personal care absorbent articles. It is another object of the present invention to form articles utilizing such perimeter barrier seals which have improved leakage control. It is still another object of the present invention to provide a perimeter barrier seal which, due to its construction, is soft, not abrasive, while providing a good seal against leakage and conforming to the user's skin so as to provide comfort to the user. It is yet a further object of the present invention to provide a perimeter barrier seal material 21~87~
which will provide a seal using relatively low tension. Many materials will provide adequate sealing properties if sufficient tension is applied to the material. The problem however is that such an approach may also r,esult in inappropriate levels of red-marking of the wearer's skin which is not desirable. These and other objects of the present invention will become more apparent upon a further review of the following specification, drawings and claims.
SUMMARY OF THE INVENTION
The present invention is directed to a perimeter barrier seal for personal care absorbent articles and the like made from a fibrous nonwoven elastic laminate. The laminate includes a high loft nonwoven facing layer, a backing layer and an elastic layer positioned between and tensionally attached to the high loft nonwoven facing layer and the backing layer to form the laminate. The high loft nonwoven facing layer contains a plurality of fibers having average fiber diameters of from about 15 to about 30 microns. If desired, the fibers may be made from or include bicomponent fibers. The resultant high loft nonwoven facing layer has a basis weight of from about 17 to about 180 grams per square meter, a density of about 0.03 grams per cubic centimeter or less and a bulk of about 0.67 millimeters or greater while under a compressive load of 6,900 dynes per square centimeter.
The backing layer should have a density which is greater than the density of the high loft nonwoven facing layer. It should also have a bulk which is lower than the bulk of the high loft nonwoven facing layer. If desired the backing layer may be made from a fibrous nonwoven web or a film. The elastic layer may be made from a number of materials including, but not limited to, elastic yarns and elastic films.
The resultant fibrous nonwoven elastic laminate can be used for a wide variety of uses including fluid containment as a perimeter barrier seal material for personal care absorbent - 215~790 articles including, for example, diapers, training pants, incontinence garments, sanitary napkins and bandages.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a perimeter barrier seal according to the present invention.
Figure 2 is a side view of a perimeter barrier seal according to the present invention.
Figure 3 is a schematic side view of a process for forming a perimeter barrier seal material according to the present invention.
Figure 4 is a top plan view of a perimeter barrier seal being incorporated into a personal care absorbent article, in this case a diaper, according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Figures 1 and 2, there is shown a perimeter barrier seal material 10 including a high loft nonwoven facing layer 12, a backing layer 14 and elastic means 16 positioned between and attached to the high loft nonwoven facing layer 12 and backing layer 14. The elastic means 16 can be a single layer of material such as a layer of elastic film or a multiplicity of elastic strands. The elastic means 16 must be a material which is "elastic" which means it is capable of being expanded to at least 2.5 times its original unit length and then upon release of the expansion forces is capable of retracting back to a length no more than 1.2 times its original unit length. As shown in Figures 1 and 2, the elastic means 16 is a plurality of elastic threads, yarns, ribbons or strands (collectively "yarns") made from such materials as polyurethane, synthetic and/or natural rubber. In addition, the elastic means 16 may be a layer of elastic material meeting the aforementioned definition of "elastic". Thus, the layer could be, for example, a sheet of natural or synthetic rubber or a layer of polyurethane.
- 215~0 An essential element of the perimeter barrier seal material 10 is the high loft nonwoven facing layer 12. This material should be a high loft fibrous nonwoven web. By high loft, it is meant a material which has a bulk of at ~east 0.67 millimeters at 6,900 dynes per square centimeter (0.1 pounds per square inch) and a density of 0.03 grams per cubic centimeter or lower. To achieve these parameters, it has been found advantageous to use a spunbond fibrous nonwoven web made from bicomponent fibers having a high melting point component and a low melting point component in, for example, a side-by-side or sheath/core configuration. Such a nonwoven web is generally nonextensible in that it cannot be stretched or expanded in the machine direction more than 1.5 times its original length without permanent deformation. By permanent deformation it is meant that once the material has been stretched 1.5 or greater times its original length and then relaxed, the relaxed length will be in excess of 1.2 times the original length. Such materials having basis weights in the range of 17 to 180 grams per square meter (gsm) with fibers having diameters in the range of about 15 to about 30 microns have been found to work well. The high and low melting point components of the bicomponent fibers can be made from a number of polymers including blends of polyolefins and/or polyolefins and polyesters. For example, polyethylene/polypropylene bicomponent fibers have been found to work particularly well.
In addition, to maintain the high loft nature of these materials, it is desirable that the bonding process for the formation of the high loft nonwoven facing layer be, for example, a through-air or infrared bonding process which provides very little compaction of the fibers during the bonding process.
A particularly well-suited high loft nonwoven web facing layer 12 is made from side-by-side polyethylene/polypropylene spunbond bicomponent fibers. The process for forming such fibers and resultant webs includes using a pair of extruders for separately supplying both the polyethylene and the polypropylene to a bicomponent spinneret.
Spinnerets for producing bicomponent fibers are well known in the art and thus are not described herein. In general, the spinneret includes a housing containing a spin pack which includes a plurality of plates having a pattern of openings arranged to create flow paths for directing the high melting and low melting polymers to each fiber-forming opening in the spinneret. The spinneret has openings arranged in one or more rows and the openings form a downwardly extending curtain of fibers when the polymers are extruded through the spinneret.
As the curtain of fibers exit the spinneret, they are contacted by a quenching gas which at least partially quenches the fibers and develops a latent helical crimp in the extending fibers.
Oftentimes the quenching air will be directed substantially perpendicular to the length of the fibers at a velocity of from about 30 to about 120 meters per minute at a temperature between about 76 and about 32C.
A fiber draw unit or aspirator is positioned below the quenching gas to receive the quenched fibers. Fiber draw units or aspirators for use in meltspinning polymers are well known in the art. Exemplary fiber draw units suitable for use in the process include linear fiber aspirators of the type shown in U.S. Patent Number 3,802,817 to Matsuki et al., U.S. Patent Number 3,423,266 to Davies et al. and U.S. Patent Number 4,340,563 to Appel et al. and eductive guns of the type shown in U.S. Patent Number 3,692,618 to Dorshner et al., all of which are incorporated herein by reference in their entirety.
The linear fiber draw unit in general has an elongated passage through which the fibers are drawn by aspirating gas. The aspirating gas may be any gas, such as air, that does not adversely interact with the polymers of the fibers. The aspirating gas can be heated as the aspirating gas draws the quenched fibers and heats the fibers to a temperature that is required to activate the latent crimps therein. The temperature required to activate the latent crimping within the fibers will range from about 43C to a r~xi~um of less than the melting point of the low melting component polymer which, in 21~9~
this case, is the polyethylene. Generally, a higher air temperature produces a higher number of crimps.
The drawn and crimped fibers are deposited onto a continuous forming surface in a random manner, ,generally assisted by a vacuum device placed underneath the forming surface. The purpose of the vacuum is to eliminate the undesirable scattering of the fibers and to guide the fibers onto the forming surface to form a uniform unbonded web of bicomponent fibers. If desired, the resultant web can be lightly compressed by a compression roller before the web is subjected to a bonding process.
To bond the bicomponent spunbonded web a through-air bonder is used. Such through-air bonders are well known in the art and therefore need not be described in detail.
Generally speaking, in the through-air bonder, a flow of heated air is forced through the web to heat the web to a temperature above the melting point of the lower melting point component of the bicomponent fibers but below the melting point of the higher melting point component. Upon heating, the lower melting polymer portion of the web fibers are melted and the melted portions of the fibers adhere to adjacent fibers at the cross-over points while the high melting polymer portions of the fibers tend to maintain the physical and dimensional integrity of the web. See U.S. Patent No. 5,336,552 to Strack et al. which is incorporated herein by reference in its entirety.
The backing layer 14 is a layer of material having a lower bulk or thickness and a higher density when compared to the high loft nonwoven facing layer 12. Suitable materials include, for example, films and nonwovens. In addition, if desired, a portion of a personal care absorbent article such as the outercover may be used as the backing layer 14. As can be seen from Figure 2, when both the facing layer 12 and backing layer 14 are fibrous nonwovens, the exposed surfaces 18 and 20 of the laminate 10 have a plurality of peaks and valleys caused by the retraction of the materials 12 and 14 due to the compressional force applied to the overall composite material 21~79Q
10 because of the retractive forces exerted by the elastic means 16. The peaks and valleys of the exposed surface 18 of the high loft nonwoven facing layer 12 are sufficiently compacted such that this surface appears sm~oth with 5 essentially no undulations when viewed with the naked eye.
This smooth surface 18 is important to provide an effective barrier seal. In contrast, the exposed surface 20 of the substrate layer 14 has noticeable surface undulations which can be viewed with the naked eye. Thus, this side of the laminate 10 10 would be unsuitable for creating an effective seal against the skin or other surface.
Attachment of the layers 12, 14 and 16 together is achieved through the use of some type of attachment means 22 such as adhesive, thermal bonding or ultrasonic bonding. One 15 suitable adhesive is Findley H-2096 hot melt adhesive from Findley Adhesives Inc. of Wauwatosa, Wisconsin.
The type of attachment means 22 chosen should be one that is compatible with the overall objectives of the present invention. Consequently, attachment means such as point 20 bonding, needling or stitching should not be chosen if they would adversely affect the surface topography of the exposed surface 18 of the high loft nonwoven facing layer 12.
Forming the perimeter barrier seal material 10 involves bringing the composite together while the elastic layer 16 is 25 under tension, subsequently releasing the tension and then allowing the laminate to relax. Referring to Figure 3, the high loft nonwoven facing layer material 12 can be formed off-line and then unrolled from a supply roll 30 as shown or the layer 12 can be formed directly in-line (not shown). At the 30 same time, a supply 32 of the elastic layer, such as yarns 16, is unwound and fed under tension on top of the high loft facing layer 12. Next, hot-melt spray adhesive 22 is sprayed down on top of and through the elastic yarns 16 from a hot-melt spray apparatus 23 such as is commercially available from J and M
35 Laboratories of Dawsonville, Georgia or Nordson Corporation of Norcross, Georgia. The hot-melt adhesive is applied evenly over the surfaces of layers 12 and 16.
21~79() After the adhesive has been applied, the backing layer 14 is unwound from supply roll 34 and brought into contact with the adhesively coated surfaces of the elastic layer 16 and the high loft nonwoven facing layer 12. The layers are,then sent through a pair of nip rolls 36 which compress the layers together under a force along the nip line of approximately 44 Newtons per linear centimeter (N/cm) (25 pounds per linear inch) to form the laminate 10. After the laminate 10 is formed, the tensioned forces are relaxed and the laminate 10 is wound-up on a take-up roll 38 for subsequent use in or conversion to an end article. Alternatively, the laminate 10 may continue in-line (not shown) for subsequent conversion. If the elastic layer 16 is a continuous film, then a second hot-melt spray apparatus 23' must also be used to make sure that all three layers will adhesively bond to one another.
Having described the laminate and process, it is also possible to use the perimeter barrier seal material in a number of applications. Due to its high loft, soft, comfortable feel, the material of the present invention can be used by itself as, for example, a headband or sweat band. It can also be used as a headband material for hats or as a cuff material about the arm, neck, waist and leg openings of garments. Another use for which the material of the present invention is particularly well-suited is as a gasketing material for personal care absorbent articles. One such embodiment, a diaper 50, is shown in Figure 4 of the drawings.
Most personal care absorbent articles include a bodyside liner 52, an outercover 54 and an absorbent core 56 disposed between the bodyside liner 52 and the outercover 54.
In addition, more full-bodied articles such as diapers will include elasticized leg openings 58. As can be seen from Figure 4, the perimeter barrier seal material 10 can be used as a gasketing means around all or a portion of the perimeter of the diaper or other personal care absorbent article 50 for the purpose of retaining body fluids such as urine, feces and menses. The backing layer 14 of the laminate 10 can be adhesively or otherwise attached to the diaper 50. Attachment - 2158791~
can take place while the laminate 10 is in a stretched or unstretched condition. The perimeter barrier seal material 10 can also be placed close to the edge of the leg opening and/or waist opening such that the perimeter barrier seal ma,terial can function as leg elastic and/or waist elastic. Furthermore, the outercover 54 can also serve as the backing layer 14.
TEST METHODS
Elonqation load and Retraction Load A 7.6 cm (3 inch) wide x 12.7 cm (5 inch) long sample was cut and clamped in the machine direction between a pair of 7.6 cm (3 inch) wide tensional jaws of an Sintech model 2/S
tensile tester. The initial jaw separation was S.1 cm (2 inches). The jaw separation distance was increased 100% to 10.2 cm (4 inches). The load value was recorded in grams and designated as the elongation load. The sample was allowed to relax by returning the jaws to the original 5.1 cm distance and then the same sample was stretched a second time to 100%
elongation or 10.2 cm. The force was then reduced until the sample reached an elongation of 30% or 6.6 cm (2.6 inches) and the 30% load value was recorded in grams and designated as the retraction load.
Fluid Barrier Test A fluid barrier test apparatus was constructed of a 15 cm long x 8.3 cm diameter solid Lucite~ rod. The diameter of the test apparatus was approximately the average diameter of the upper portion of a baby's leg. A 2.5 cm wide x 11.4 cm high x 5 mm deep rectangular pocket was machined into the perimeter surface of the rod and this formed the three sides of a fluid compartment. Sample bands of perimeter barrier seal material were stretched and placed over the bottom 2.5 cm portion of the fluid compartment. Distilled water was poured into the compartment and then viewed to see whether it would 21~879~
leak out the bottom of the compartment and down the Lucite~ rod thereby simulating a leak as would occur between a baby's leg and the leg opening of a diaper.
To form the bands, a 5 cm wide sample of the perimeter barrier seal material was cut to 18.5 cm in length. The short ends of the sample were joined together to form a band using adhesive tape and the band was stretched to fit the perimeter (25.9 cm) of the test apparatus with the facing layer 12 positioned adjacent the Lucite~ rod. As a result, the sample was stretched to 40% elongation during testing. The top 2.5 cm x 2.5 cm area of the sample was used to form the fourth side of the fluid compartment, while the bottom 2.5 cm x 2.5 cm area of the sample was subjected to the penetration of the distilled water test fluid. If the seal between the facing layer 12 and the Lucite rod was not sufficient, the test fluid would move along the interface between the test apparatus and sample in a x-direction if the stretch direction is designated as the y-direction and the thickness of the sample as the z-direction.
The test method was designed to simulate the use situation where the sample material is used as leg cuff elastic and when the baby is in a standing position. For each test the fluid compartment was filled with approximately 3 cubic centimeters of test fluid.
The time that it took for any test fluid to leak through the interface between the test apparatus and the bottom of the sample was recorded. A sample was considered to have "passed" if there was no leakage in the x-direction after 60 minutes. The fluid barrier performance was expressed as the percentage of tests wherein the sample could hold the fluid for greater than 60 minutes over the total number of tests performed with the quantity being multiplied by 100. On average ten tests were run for each sample.
The following Examples are presented to provide a more detailed understanding of the invention. The Examples are intended to be representative and are not intended to specifically limit the scope of the invention 21587~0 EXAMPLES
Example I
In Example I a three layer perimeter barrier seal material was made. The high loft facing layer was a 102 gram per square meter (gsm) through-air bonded, bicomponent fiber spunbond nonwoven web. The fibers were of a side-by-side construction using ASPUN~ 6811A polyethylene from the Dow Chemical Company of Midland, Michigan and a PP3445 polypropylene from the Exxon Chemical Company of Houston, Texas. The fibers were highly crimped to yield a high loft structure. The number of crimps per extended inch was from 3 to 10 as measured by ASTM test method D-3937-82. The extruded fibers had an average fiber lS diameter of about 23 microns with a range between about 20 and about 25 microns. The essentially continuous fiber web was laid down on a forming surface and through-air bonded at an air temperature of approximately 125C and an average air velocity of approximately 43 meters per min (m/min) for a period of approximately 2.8 seconds at a line speed of 13 meters per minute. The polyethylene was the lower melting point component of the fiber and therefore served as the bonding agent for the web. It had a melt index of 26 grams per 10 minutes at 190C
as measured in accordance with ASTM standard D-1238-85 (Condition E), The polypropylene portion of the fiber had a melt index of 35 grams per 10 minutes at 230C in accordance with ASTM standard D-1238-85 (Condition L).
The backing layer 14 was a bicomponent fiber spunbond web made from the same materials and fibers as the facing layer. The only differences were that the fibers had a low crimp (approximately 1 or fewer crimps per extended inch using ASTM test method D-3937-82), the web had a basis weight of 17 gsm and there was a higher degree of through-air bonding.
Bonding took place at an air temperature of approximately 131C
with an air velocity of 55 m/min for a period of approximately 0.5 seconds at a line speed of 82 meters per minute.
21~87$~
The elastic middle layer was made from 940 decitex Lycra~ Spandex monofil yarns which are available from E. I.
DuPont de Nemours of Wilmington, Delaware. Spacing between the yarns was approximately 4.5 mm (6 yarns per inch). , Three separate laminate samples were made using the above-described materials, the difference being the level of stretch in the yarns prior to their lamination between the facing and backing layers. For Sample Ia the yarns were stretched 300 percent or 4.0 times their relaxed length before being attached to the other two layers while in a tensioned state. For Sample Ib the level of stretching prior to attachment was 200 percent or 3 times the relaxed length and for Sample Ic the yarns were stretched 150 percent or 2.5 times their relaxed length prior to attachment.
A Findley H-2096 hot melt, KRATON~ rubber-based adhesive was used to laminate the layers together. The Lycra~
yarns were brought down, while in a stretched state, on top of the high loft nonwoven facing layer material. The hot melt adhesive was sprayed down onto the yarns and through to the facing layer in a uniform and continuous pattern at a point just before contact of the fibers with the facing layer and at a rate of 10 grams per square meter. Next the backing layer was brought down on top of the adhesive-coated yarns and the composite was run through a pair of nip rollers with a nip force of 44 Newtons per linear centimeter (N/cm) (25 pounds per linear inch). Once the laminate was formed, it was then allowed to relax, thereby contracting the facing and backing layer materials.
A 10 centimeter by 10 centimeter sample of each of the three laminates was visually inspected. The exposed surface of the facing layer when viewed by the naked eye (20/20 corrected vision) in a Macbeth~ PROOFLIT~ viewing system booth (7500K
light source) at a distance of 0.6 meters had a flat surface with substantially no noticeable surface undulations running generally perpendicular to the major direction of stretch of the elastic layer. In contrast, the exposed surface of the - 21587~
backing layer did have noticeable surface undulations when viewed in the same manner as the facing layer.
In addition to visual observations of the laminates according to the present invention, physical testing of the samples was also performed. The fluid barrier test was performed on each of the samples. Samples of the material designated Ia passed the test 100 percent of the time. Samples of the Ib material passed 70 percent of the time and samples of the Ic material passed 90 percent of the time. Testing included elongation load (A), retraction load (B), and fluid barrier properties (C). The test results are set forth in Table I below.
215~7~1~
TABLE I
Sample A B C
Elongation RetractionFluid Barrier (%) Load (g) Load (g) Ia 1007 267 100 Ib 995 271 70 Ic 1067 261 90 IIa 1007 267 30 IIb ~ 87 215~790 Example II
A factor contributing to the barrier properties of the present invention is believed to be the level of bonding in the high loft facing layer. Through-air bonding, as opposed to point bonding, allows for very light, uniform bonding of the fibers to one another at their cross-over points using only heated air as opposed to localized heat and pressure with point bonding or overall pressure bonding using heated calender rolls. However, with through-air bonding it is also possible to bring about extensive bonding depending upon the air temperature and flow rate, and the dwell time inside the through-air bonder. To demonstrate this, two sample laminates were made in Example II which were identical except for the level of bonding of the high loft facing layer.
The elastic layer for Samples IIa and IIb were both the same as that used in Example I. The level of stretch in each sample was equal to 300 percent. The hot melt adhesive was the same as that used in the previous examples with an application rate of 10 gsm and the backing layer for both samples was the same as that used in Example I. The difference between Sample IIa and IIb was the level of through-air bonding in the high loft nonwoven facing layer. Both samples use a 102 gsm polyethylene/polypropylene bicomponent spunbond web of the same type as used in Example I. Fiber diameters for both samples was about 20 microns with a range between about 17 microns and about 23 microns. After laying down the fibers forming the high loft nonwoven web facing layer of Sample IIa, the web was subjected to through-air bonding at a temperature of approximately 123C and an air velocity of 60 m/min. for 7 seconds. In contrast, Sample IIb was through-air bonded at a temperature of approximately 126C and an air velocity of 43 m/min. for 2.4 seconds. After the two webs were formed, they were each formed into laminates using the above-described components. The laminate of Sample IIa was noticeably stiffer and more harsh feeling to the touch than Sample IIb. The same physical tests were run as with the other samples and the 21~7~
-results are reported in Table I. In addition, a compression/bulk test was performed on each sample.
To perform the compression/bulk test, a 4 cm by 4 cm sample was placed under a compressive load of 0.1 pounds per S square inch (6,900 dynes per square centimeter) and the bulk or thickness of the sample was measured and recorded. Under 0.1 psi, the more highly bonded Sample IIa had a bulk of 4.55 millimeters and the lightly bonded Sample IIb had a bulk measurement of 5.13 millimeters. Next the same sample of each material was placed under a 0.5 psi (34,500 dynes per square centimeter) load and the bulk or thickness was measured to be 3.73 millimeters for Sample IIa and 4.14 millimeters (mm) for Sample IIb. The bulk of Sample IIa decreased by 0.82 mm when the pressure was increased from 0.1 to 0.5 psi whereas, for Sample IIb, the bulk of the sample decreased by 0.99 mm under the same conditions. Thus it can be seen that the sample with the higher degree of bonding, Sample IIa, was more resistant to compression. As a result, it is believed that there was less compression of the fibers during the barrier leakage testing of Sample IIa and thus more void space between the perimeter barrier seal and the wearer's skin which permitted greater liquid penetration and therefore higher leakage.
Example III
In Example III, the backing layer and adhesive were the same as Example I. The high loft facing layer was approximately 68 gsm but otherwise the same as in Example IIa.
In Example III the elastic was Lycra~ 940 Decitex yarn with a spacing of approximately 4.5 mm (6 yarns per inch). The yarn was stretched 300 percent prior to incorporation into the laminate construction. Test results are given in Table I.
Example IV
In Example IV, the high loft facing layer, the backing layer, the adhesive and its application rate were the same as 21i~73i that in Example III. The difference was in the elastic layer.
For Example IV the elastic layer comprised strands of isoprene rubber manufactured by JPS Elastomerics Corporation of Charlotte, North Carolina and sold using the trade designation TS-233. The strands were 8 mm (5/64 inch) wide and 0.33 mm (13/1000 inch) thick and had a spacing of 6 strands per 2.54 centimeters. The strands for Sample IV were stretched 300 percent (the same as Examples Ia, II and III) prior to attachment to the facing and backing layers. A visual inspection of each sample using the same criteria as in Example I yielded the same observations. Namely, the exposed surface of the facing layer had substantially no noticeable surface undulations running perpendicular to the major direction of stretch (machine direction) of the elastic layer and the exposed surface of the backing layer did have noticeable surface undulations. Results from the physical testing of Example IV are set forth in Table I.
Example V
The facing layer, adhesive and adhesive add-on level for Example V were the same as in Examples III and IV. No backing layer was used for the sample in Example V and the elastic layer was a continuous layer of 1 mil thick polyurethane film from Deerfield Urethane of South Deerfield, Massachusetts and sold under the trade designation Dureflex~.
As with the previous examples, the level of stretch of the elastic layer prior to attachment in Sample V was 300 percent.
The process for making the laminate was the same as in the previous examples except that the 10 gsm of adhesive was applied between the facing and elastic layers. The layers and adhesive were nipped between a pair of nip rollers at a nip force of 44 Newtons per linear centimeter (N/cm) (25 pounds per linear inch) and the laminate was then allowed to relax.
A visual inspection of the exposed surface of the facing layer indicated substantially no noticeable surface undulations. The exposed surface of the polyurethane film also had no noticeable surface undulations. Results from the physical testing are set forth in Table I.
ExamPle VI
In Example VI, as compared to Example IIa, the spacing between the Lycra~ monofilament yarns was decreased to approximately 3.2 mm (8 yarns per inch). All other aspects of the samples were the same including the degree of stretch (300%).
A visual inspection of the samples yielded the same observations as with the Example I. Results from the physical testing are set forth in Table I. As can be seen from the fluid barrier test results, the laminates of Example IIa did not provide as good a barrier seal as the laminate of Example VI. As a result, it is evident that a higher retraction force is advantageous with respect to providing an appropriate barrier seal.
Example VII
In Example VII the facing and elastic layers were the same as in Example I and the adhesive application rate was reduced from 10 gsm to 8 gsm. The backing layer was a 0.5 mil polyethylene film from Consolidated Thermoplastics of Schaumburg, Illinois and was designated LSF-22. The sample was prepared with 250 percent stretch in the elastic layer prior to attachment. Visual inspections resulted in the same observations as with Example I with respect to the exposed surfaces of the facing and backing layers. Results from the physical testing are set forth in Table I.
ARTICLES AND THE LIKE
FIELD OF THE INVENTION
The present invention is directed to a perimeter barrier seal material. More particularly, the present invention is directed to a perimeter barrier seal material which is suitable for use as a gasketing means which can be used about the periphery of such personal care absorbent articles as, for example, diapers to reduce leakage of liquids about the leg and/or waist openings of the article.
BACKGROUND OF THE INVENTION
The primary purpose of personal care absorbent articles such as diapers, training pants, incontinence garments, sanitary napkins, bandages and the like is to absorb and retain exudated body fluids. Rapid up-take of liquids such as urine has been a long standing problem in the design of such personal care absorbent articles, especially with respect to such articles as diapers, training pants and incontinence garments.
Such factors as article design, the speed and/or amount of the delivered insult and repeated insults oftentimes result in a quantity of liquid which cannot be quickly absorbed into the article. The natural tendancy of the nonabsorbed liquid is to flow across the interior surface of the article and exit the article wherever possible. For full body fitting articles such as diapers, incontinence garments and training pants, the primary place for escape is around the leg openings and, 21~7~
secondarily, around the waist opening. Consequently, if the article cannot handle the insult, the liquid or other body waste material will try to exit one of these openings.
In an attempt to stem the flow of liquid ou,t the leg openings in such personal care absorbent articles, diapers were first fitted with leg elastic about the leg openings. Next, the diapers were fitted with leg flaps which were installed on the interior surface of the diapers inboard of the leg elastics. The same types of leg flaps are now being employed in training pants to also further retard leakage. Such leg flaps are usually made from thin elasticized strips of material which extend upwardly from the plane of the diaper approximately 3 centimeters (cm~ and which are typically about 0.5 to about O.g millimeters (mm) thick. During use, such leg flaps typically are folded over and lay rather flat against the torso of the wearer.
While the leg openings are the most common area for leakage from personal care absorbent articles such as diapers, training pants and incontinence garments, it is also possible to experience leakage about the waistband of such articles. In an attempt to reduce leakage in this area, it is now not an uncommon practice to employ elastic in all or a part of the waistband region of the article so as to increase the tensional fit of the garment against the torso of the wearer. Here again, such designs have been met with varying degrees of success.
It is an aspect of the present invention to provide a perimeter barrier seal which can be used as a gasket about all or a portion of such personal care absorbent articles. It is another object of the present invention to form articles utilizing such perimeter barrier seals which have improved leakage control. It is still another object of the present invention to provide a perimeter barrier seal which, due to its construction, is soft, not abrasive, while providing a good seal against leakage and conforming to the user's skin so as to provide comfort to the user. It is yet a further object of the present invention to provide a perimeter barrier seal material 21~87~
which will provide a seal using relatively low tension. Many materials will provide adequate sealing properties if sufficient tension is applied to the material. The problem however is that such an approach may also r,esult in inappropriate levels of red-marking of the wearer's skin which is not desirable. These and other objects of the present invention will become more apparent upon a further review of the following specification, drawings and claims.
SUMMARY OF THE INVENTION
The present invention is directed to a perimeter barrier seal for personal care absorbent articles and the like made from a fibrous nonwoven elastic laminate. The laminate includes a high loft nonwoven facing layer, a backing layer and an elastic layer positioned between and tensionally attached to the high loft nonwoven facing layer and the backing layer to form the laminate. The high loft nonwoven facing layer contains a plurality of fibers having average fiber diameters of from about 15 to about 30 microns. If desired, the fibers may be made from or include bicomponent fibers. The resultant high loft nonwoven facing layer has a basis weight of from about 17 to about 180 grams per square meter, a density of about 0.03 grams per cubic centimeter or less and a bulk of about 0.67 millimeters or greater while under a compressive load of 6,900 dynes per square centimeter.
The backing layer should have a density which is greater than the density of the high loft nonwoven facing layer. It should also have a bulk which is lower than the bulk of the high loft nonwoven facing layer. If desired the backing layer may be made from a fibrous nonwoven web or a film. The elastic layer may be made from a number of materials including, but not limited to, elastic yarns and elastic films.
The resultant fibrous nonwoven elastic laminate can be used for a wide variety of uses including fluid containment as a perimeter barrier seal material for personal care absorbent - 215~790 articles including, for example, diapers, training pants, incontinence garments, sanitary napkins and bandages.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective view of a perimeter barrier seal according to the present invention.
Figure 2 is a side view of a perimeter barrier seal according to the present invention.
Figure 3 is a schematic side view of a process for forming a perimeter barrier seal material according to the present invention.
Figure 4 is a top plan view of a perimeter barrier seal being incorporated into a personal care absorbent article, in this case a diaper, according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Figures 1 and 2, there is shown a perimeter barrier seal material 10 including a high loft nonwoven facing layer 12, a backing layer 14 and elastic means 16 positioned between and attached to the high loft nonwoven facing layer 12 and backing layer 14. The elastic means 16 can be a single layer of material such as a layer of elastic film or a multiplicity of elastic strands. The elastic means 16 must be a material which is "elastic" which means it is capable of being expanded to at least 2.5 times its original unit length and then upon release of the expansion forces is capable of retracting back to a length no more than 1.2 times its original unit length. As shown in Figures 1 and 2, the elastic means 16 is a plurality of elastic threads, yarns, ribbons or strands (collectively "yarns") made from such materials as polyurethane, synthetic and/or natural rubber. In addition, the elastic means 16 may be a layer of elastic material meeting the aforementioned definition of "elastic". Thus, the layer could be, for example, a sheet of natural or synthetic rubber or a layer of polyurethane.
- 215~0 An essential element of the perimeter barrier seal material 10 is the high loft nonwoven facing layer 12. This material should be a high loft fibrous nonwoven web. By high loft, it is meant a material which has a bulk of at ~east 0.67 millimeters at 6,900 dynes per square centimeter (0.1 pounds per square inch) and a density of 0.03 grams per cubic centimeter or lower. To achieve these parameters, it has been found advantageous to use a spunbond fibrous nonwoven web made from bicomponent fibers having a high melting point component and a low melting point component in, for example, a side-by-side or sheath/core configuration. Such a nonwoven web is generally nonextensible in that it cannot be stretched or expanded in the machine direction more than 1.5 times its original length without permanent deformation. By permanent deformation it is meant that once the material has been stretched 1.5 or greater times its original length and then relaxed, the relaxed length will be in excess of 1.2 times the original length. Such materials having basis weights in the range of 17 to 180 grams per square meter (gsm) with fibers having diameters in the range of about 15 to about 30 microns have been found to work well. The high and low melting point components of the bicomponent fibers can be made from a number of polymers including blends of polyolefins and/or polyolefins and polyesters. For example, polyethylene/polypropylene bicomponent fibers have been found to work particularly well.
In addition, to maintain the high loft nature of these materials, it is desirable that the bonding process for the formation of the high loft nonwoven facing layer be, for example, a through-air or infrared bonding process which provides very little compaction of the fibers during the bonding process.
A particularly well-suited high loft nonwoven web facing layer 12 is made from side-by-side polyethylene/polypropylene spunbond bicomponent fibers. The process for forming such fibers and resultant webs includes using a pair of extruders for separately supplying both the polyethylene and the polypropylene to a bicomponent spinneret.
Spinnerets for producing bicomponent fibers are well known in the art and thus are not described herein. In general, the spinneret includes a housing containing a spin pack which includes a plurality of plates having a pattern of openings arranged to create flow paths for directing the high melting and low melting polymers to each fiber-forming opening in the spinneret. The spinneret has openings arranged in one or more rows and the openings form a downwardly extending curtain of fibers when the polymers are extruded through the spinneret.
As the curtain of fibers exit the spinneret, they are contacted by a quenching gas which at least partially quenches the fibers and develops a latent helical crimp in the extending fibers.
Oftentimes the quenching air will be directed substantially perpendicular to the length of the fibers at a velocity of from about 30 to about 120 meters per minute at a temperature between about 76 and about 32C.
A fiber draw unit or aspirator is positioned below the quenching gas to receive the quenched fibers. Fiber draw units or aspirators for use in meltspinning polymers are well known in the art. Exemplary fiber draw units suitable for use in the process include linear fiber aspirators of the type shown in U.S. Patent Number 3,802,817 to Matsuki et al., U.S. Patent Number 3,423,266 to Davies et al. and U.S. Patent Number 4,340,563 to Appel et al. and eductive guns of the type shown in U.S. Patent Number 3,692,618 to Dorshner et al., all of which are incorporated herein by reference in their entirety.
The linear fiber draw unit in general has an elongated passage through which the fibers are drawn by aspirating gas. The aspirating gas may be any gas, such as air, that does not adversely interact with the polymers of the fibers. The aspirating gas can be heated as the aspirating gas draws the quenched fibers and heats the fibers to a temperature that is required to activate the latent crimps therein. The temperature required to activate the latent crimping within the fibers will range from about 43C to a r~xi~um of less than the melting point of the low melting component polymer which, in 21~9~
this case, is the polyethylene. Generally, a higher air temperature produces a higher number of crimps.
The drawn and crimped fibers are deposited onto a continuous forming surface in a random manner, ,generally assisted by a vacuum device placed underneath the forming surface. The purpose of the vacuum is to eliminate the undesirable scattering of the fibers and to guide the fibers onto the forming surface to form a uniform unbonded web of bicomponent fibers. If desired, the resultant web can be lightly compressed by a compression roller before the web is subjected to a bonding process.
To bond the bicomponent spunbonded web a through-air bonder is used. Such through-air bonders are well known in the art and therefore need not be described in detail.
Generally speaking, in the through-air bonder, a flow of heated air is forced through the web to heat the web to a temperature above the melting point of the lower melting point component of the bicomponent fibers but below the melting point of the higher melting point component. Upon heating, the lower melting polymer portion of the web fibers are melted and the melted portions of the fibers adhere to adjacent fibers at the cross-over points while the high melting polymer portions of the fibers tend to maintain the physical and dimensional integrity of the web. See U.S. Patent No. 5,336,552 to Strack et al. which is incorporated herein by reference in its entirety.
The backing layer 14 is a layer of material having a lower bulk or thickness and a higher density when compared to the high loft nonwoven facing layer 12. Suitable materials include, for example, films and nonwovens. In addition, if desired, a portion of a personal care absorbent article such as the outercover may be used as the backing layer 14. As can be seen from Figure 2, when both the facing layer 12 and backing layer 14 are fibrous nonwovens, the exposed surfaces 18 and 20 of the laminate 10 have a plurality of peaks and valleys caused by the retraction of the materials 12 and 14 due to the compressional force applied to the overall composite material 21~79Q
10 because of the retractive forces exerted by the elastic means 16. The peaks and valleys of the exposed surface 18 of the high loft nonwoven facing layer 12 are sufficiently compacted such that this surface appears sm~oth with 5 essentially no undulations when viewed with the naked eye.
This smooth surface 18 is important to provide an effective barrier seal. In contrast, the exposed surface 20 of the substrate layer 14 has noticeable surface undulations which can be viewed with the naked eye. Thus, this side of the laminate 10 10 would be unsuitable for creating an effective seal against the skin or other surface.
Attachment of the layers 12, 14 and 16 together is achieved through the use of some type of attachment means 22 such as adhesive, thermal bonding or ultrasonic bonding. One 15 suitable adhesive is Findley H-2096 hot melt adhesive from Findley Adhesives Inc. of Wauwatosa, Wisconsin.
The type of attachment means 22 chosen should be one that is compatible with the overall objectives of the present invention. Consequently, attachment means such as point 20 bonding, needling or stitching should not be chosen if they would adversely affect the surface topography of the exposed surface 18 of the high loft nonwoven facing layer 12.
Forming the perimeter barrier seal material 10 involves bringing the composite together while the elastic layer 16 is 25 under tension, subsequently releasing the tension and then allowing the laminate to relax. Referring to Figure 3, the high loft nonwoven facing layer material 12 can be formed off-line and then unrolled from a supply roll 30 as shown or the layer 12 can be formed directly in-line (not shown). At the 30 same time, a supply 32 of the elastic layer, such as yarns 16, is unwound and fed under tension on top of the high loft facing layer 12. Next, hot-melt spray adhesive 22 is sprayed down on top of and through the elastic yarns 16 from a hot-melt spray apparatus 23 such as is commercially available from J and M
35 Laboratories of Dawsonville, Georgia or Nordson Corporation of Norcross, Georgia. The hot-melt adhesive is applied evenly over the surfaces of layers 12 and 16.
21~79() After the adhesive has been applied, the backing layer 14 is unwound from supply roll 34 and brought into contact with the adhesively coated surfaces of the elastic layer 16 and the high loft nonwoven facing layer 12. The layers are,then sent through a pair of nip rolls 36 which compress the layers together under a force along the nip line of approximately 44 Newtons per linear centimeter (N/cm) (25 pounds per linear inch) to form the laminate 10. After the laminate 10 is formed, the tensioned forces are relaxed and the laminate 10 is wound-up on a take-up roll 38 for subsequent use in or conversion to an end article. Alternatively, the laminate 10 may continue in-line (not shown) for subsequent conversion. If the elastic layer 16 is a continuous film, then a second hot-melt spray apparatus 23' must also be used to make sure that all three layers will adhesively bond to one another.
Having described the laminate and process, it is also possible to use the perimeter barrier seal material in a number of applications. Due to its high loft, soft, comfortable feel, the material of the present invention can be used by itself as, for example, a headband or sweat band. It can also be used as a headband material for hats or as a cuff material about the arm, neck, waist and leg openings of garments. Another use for which the material of the present invention is particularly well-suited is as a gasketing material for personal care absorbent articles. One such embodiment, a diaper 50, is shown in Figure 4 of the drawings.
Most personal care absorbent articles include a bodyside liner 52, an outercover 54 and an absorbent core 56 disposed between the bodyside liner 52 and the outercover 54.
In addition, more full-bodied articles such as diapers will include elasticized leg openings 58. As can be seen from Figure 4, the perimeter barrier seal material 10 can be used as a gasketing means around all or a portion of the perimeter of the diaper or other personal care absorbent article 50 for the purpose of retaining body fluids such as urine, feces and menses. The backing layer 14 of the laminate 10 can be adhesively or otherwise attached to the diaper 50. Attachment - 2158791~
can take place while the laminate 10 is in a stretched or unstretched condition. The perimeter barrier seal material 10 can also be placed close to the edge of the leg opening and/or waist opening such that the perimeter barrier seal ma,terial can function as leg elastic and/or waist elastic. Furthermore, the outercover 54 can also serve as the backing layer 14.
TEST METHODS
Elonqation load and Retraction Load A 7.6 cm (3 inch) wide x 12.7 cm (5 inch) long sample was cut and clamped in the machine direction between a pair of 7.6 cm (3 inch) wide tensional jaws of an Sintech model 2/S
tensile tester. The initial jaw separation was S.1 cm (2 inches). The jaw separation distance was increased 100% to 10.2 cm (4 inches). The load value was recorded in grams and designated as the elongation load. The sample was allowed to relax by returning the jaws to the original 5.1 cm distance and then the same sample was stretched a second time to 100%
elongation or 10.2 cm. The force was then reduced until the sample reached an elongation of 30% or 6.6 cm (2.6 inches) and the 30% load value was recorded in grams and designated as the retraction load.
Fluid Barrier Test A fluid barrier test apparatus was constructed of a 15 cm long x 8.3 cm diameter solid Lucite~ rod. The diameter of the test apparatus was approximately the average diameter of the upper portion of a baby's leg. A 2.5 cm wide x 11.4 cm high x 5 mm deep rectangular pocket was machined into the perimeter surface of the rod and this formed the three sides of a fluid compartment. Sample bands of perimeter barrier seal material were stretched and placed over the bottom 2.5 cm portion of the fluid compartment. Distilled water was poured into the compartment and then viewed to see whether it would 21~879~
leak out the bottom of the compartment and down the Lucite~ rod thereby simulating a leak as would occur between a baby's leg and the leg opening of a diaper.
To form the bands, a 5 cm wide sample of the perimeter barrier seal material was cut to 18.5 cm in length. The short ends of the sample were joined together to form a band using adhesive tape and the band was stretched to fit the perimeter (25.9 cm) of the test apparatus with the facing layer 12 positioned adjacent the Lucite~ rod. As a result, the sample was stretched to 40% elongation during testing. The top 2.5 cm x 2.5 cm area of the sample was used to form the fourth side of the fluid compartment, while the bottom 2.5 cm x 2.5 cm area of the sample was subjected to the penetration of the distilled water test fluid. If the seal between the facing layer 12 and the Lucite rod was not sufficient, the test fluid would move along the interface between the test apparatus and sample in a x-direction if the stretch direction is designated as the y-direction and the thickness of the sample as the z-direction.
The test method was designed to simulate the use situation where the sample material is used as leg cuff elastic and when the baby is in a standing position. For each test the fluid compartment was filled with approximately 3 cubic centimeters of test fluid.
The time that it took for any test fluid to leak through the interface between the test apparatus and the bottom of the sample was recorded. A sample was considered to have "passed" if there was no leakage in the x-direction after 60 minutes. The fluid barrier performance was expressed as the percentage of tests wherein the sample could hold the fluid for greater than 60 minutes over the total number of tests performed with the quantity being multiplied by 100. On average ten tests were run for each sample.
The following Examples are presented to provide a more detailed understanding of the invention. The Examples are intended to be representative and are not intended to specifically limit the scope of the invention 21587~0 EXAMPLES
Example I
In Example I a three layer perimeter barrier seal material was made. The high loft facing layer was a 102 gram per square meter (gsm) through-air bonded, bicomponent fiber spunbond nonwoven web. The fibers were of a side-by-side construction using ASPUN~ 6811A polyethylene from the Dow Chemical Company of Midland, Michigan and a PP3445 polypropylene from the Exxon Chemical Company of Houston, Texas. The fibers were highly crimped to yield a high loft structure. The number of crimps per extended inch was from 3 to 10 as measured by ASTM test method D-3937-82. The extruded fibers had an average fiber lS diameter of about 23 microns with a range between about 20 and about 25 microns. The essentially continuous fiber web was laid down on a forming surface and through-air bonded at an air temperature of approximately 125C and an average air velocity of approximately 43 meters per min (m/min) for a period of approximately 2.8 seconds at a line speed of 13 meters per minute. The polyethylene was the lower melting point component of the fiber and therefore served as the bonding agent for the web. It had a melt index of 26 grams per 10 minutes at 190C
as measured in accordance with ASTM standard D-1238-85 (Condition E), The polypropylene portion of the fiber had a melt index of 35 grams per 10 minutes at 230C in accordance with ASTM standard D-1238-85 (Condition L).
The backing layer 14 was a bicomponent fiber spunbond web made from the same materials and fibers as the facing layer. The only differences were that the fibers had a low crimp (approximately 1 or fewer crimps per extended inch using ASTM test method D-3937-82), the web had a basis weight of 17 gsm and there was a higher degree of through-air bonding.
Bonding took place at an air temperature of approximately 131C
with an air velocity of 55 m/min for a period of approximately 0.5 seconds at a line speed of 82 meters per minute.
21~87$~
The elastic middle layer was made from 940 decitex Lycra~ Spandex monofil yarns which are available from E. I.
DuPont de Nemours of Wilmington, Delaware. Spacing between the yarns was approximately 4.5 mm (6 yarns per inch). , Three separate laminate samples were made using the above-described materials, the difference being the level of stretch in the yarns prior to their lamination between the facing and backing layers. For Sample Ia the yarns were stretched 300 percent or 4.0 times their relaxed length before being attached to the other two layers while in a tensioned state. For Sample Ib the level of stretching prior to attachment was 200 percent or 3 times the relaxed length and for Sample Ic the yarns were stretched 150 percent or 2.5 times their relaxed length prior to attachment.
A Findley H-2096 hot melt, KRATON~ rubber-based adhesive was used to laminate the layers together. The Lycra~
yarns were brought down, while in a stretched state, on top of the high loft nonwoven facing layer material. The hot melt adhesive was sprayed down onto the yarns and through to the facing layer in a uniform and continuous pattern at a point just before contact of the fibers with the facing layer and at a rate of 10 grams per square meter. Next the backing layer was brought down on top of the adhesive-coated yarns and the composite was run through a pair of nip rollers with a nip force of 44 Newtons per linear centimeter (N/cm) (25 pounds per linear inch). Once the laminate was formed, it was then allowed to relax, thereby contracting the facing and backing layer materials.
A 10 centimeter by 10 centimeter sample of each of the three laminates was visually inspected. The exposed surface of the facing layer when viewed by the naked eye (20/20 corrected vision) in a Macbeth~ PROOFLIT~ viewing system booth (7500K
light source) at a distance of 0.6 meters had a flat surface with substantially no noticeable surface undulations running generally perpendicular to the major direction of stretch of the elastic layer. In contrast, the exposed surface of the - 21587~
backing layer did have noticeable surface undulations when viewed in the same manner as the facing layer.
In addition to visual observations of the laminates according to the present invention, physical testing of the samples was also performed. The fluid barrier test was performed on each of the samples. Samples of the material designated Ia passed the test 100 percent of the time. Samples of the Ib material passed 70 percent of the time and samples of the Ic material passed 90 percent of the time. Testing included elongation load (A), retraction load (B), and fluid barrier properties (C). The test results are set forth in Table I below.
215~7~1~
TABLE I
Sample A B C
Elongation RetractionFluid Barrier (%) Load (g) Load (g) Ia 1007 267 100 Ib 995 271 70 Ic 1067 261 90 IIa 1007 267 30 IIb ~ 87 215~790 Example II
A factor contributing to the barrier properties of the present invention is believed to be the level of bonding in the high loft facing layer. Through-air bonding, as opposed to point bonding, allows for very light, uniform bonding of the fibers to one another at their cross-over points using only heated air as opposed to localized heat and pressure with point bonding or overall pressure bonding using heated calender rolls. However, with through-air bonding it is also possible to bring about extensive bonding depending upon the air temperature and flow rate, and the dwell time inside the through-air bonder. To demonstrate this, two sample laminates were made in Example II which were identical except for the level of bonding of the high loft facing layer.
The elastic layer for Samples IIa and IIb were both the same as that used in Example I. The level of stretch in each sample was equal to 300 percent. The hot melt adhesive was the same as that used in the previous examples with an application rate of 10 gsm and the backing layer for both samples was the same as that used in Example I. The difference between Sample IIa and IIb was the level of through-air bonding in the high loft nonwoven facing layer. Both samples use a 102 gsm polyethylene/polypropylene bicomponent spunbond web of the same type as used in Example I. Fiber diameters for both samples was about 20 microns with a range between about 17 microns and about 23 microns. After laying down the fibers forming the high loft nonwoven web facing layer of Sample IIa, the web was subjected to through-air bonding at a temperature of approximately 123C and an air velocity of 60 m/min. for 7 seconds. In contrast, Sample IIb was through-air bonded at a temperature of approximately 126C and an air velocity of 43 m/min. for 2.4 seconds. After the two webs were formed, they were each formed into laminates using the above-described components. The laminate of Sample IIa was noticeably stiffer and more harsh feeling to the touch than Sample IIb. The same physical tests were run as with the other samples and the 21~7~
-results are reported in Table I. In addition, a compression/bulk test was performed on each sample.
To perform the compression/bulk test, a 4 cm by 4 cm sample was placed under a compressive load of 0.1 pounds per S square inch (6,900 dynes per square centimeter) and the bulk or thickness of the sample was measured and recorded. Under 0.1 psi, the more highly bonded Sample IIa had a bulk of 4.55 millimeters and the lightly bonded Sample IIb had a bulk measurement of 5.13 millimeters. Next the same sample of each material was placed under a 0.5 psi (34,500 dynes per square centimeter) load and the bulk or thickness was measured to be 3.73 millimeters for Sample IIa and 4.14 millimeters (mm) for Sample IIb. The bulk of Sample IIa decreased by 0.82 mm when the pressure was increased from 0.1 to 0.5 psi whereas, for Sample IIb, the bulk of the sample decreased by 0.99 mm under the same conditions. Thus it can be seen that the sample with the higher degree of bonding, Sample IIa, was more resistant to compression. As a result, it is believed that there was less compression of the fibers during the barrier leakage testing of Sample IIa and thus more void space between the perimeter barrier seal and the wearer's skin which permitted greater liquid penetration and therefore higher leakage.
Example III
In Example III, the backing layer and adhesive were the same as Example I. The high loft facing layer was approximately 68 gsm but otherwise the same as in Example IIa.
In Example III the elastic was Lycra~ 940 Decitex yarn with a spacing of approximately 4.5 mm (6 yarns per inch). The yarn was stretched 300 percent prior to incorporation into the laminate construction. Test results are given in Table I.
Example IV
In Example IV, the high loft facing layer, the backing layer, the adhesive and its application rate were the same as 21i~73i that in Example III. The difference was in the elastic layer.
For Example IV the elastic layer comprised strands of isoprene rubber manufactured by JPS Elastomerics Corporation of Charlotte, North Carolina and sold using the trade designation TS-233. The strands were 8 mm (5/64 inch) wide and 0.33 mm (13/1000 inch) thick and had a spacing of 6 strands per 2.54 centimeters. The strands for Sample IV were stretched 300 percent (the same as Examples Ia, II and III) prior to attachment to the facing and backing layers. A visual inspection of each sample using the same criteria as in Example I yielded the same observations. Namely, the exposed surface of the facing layer had substantially no noticeable surface undulations running perpendicular to the major direction of stretch (machine direction) of the elastic layer and the exposed surface of the backing layer did have noticeable surface undulations. Results from the physical testing of Example IV are set forth in Table I.
Example V
The facing layer, adhesive and adhesive add-on level for Example V were the same as in Examples III and IV. No backing layer was used for the sample in Example V and the elastic layer was a continuous layer of 1 mil thick polyurethane film from Deerfield Urethane of South Deerfield, Massachusetts and sold under the trade designation Dureflex~.
As with the previous examples, the level of stretch of the elastic layer prior to attachment in Sample V was 300 percent.
The process for making the laminate was the same as in the previous examples except that the 10 gsm of adhesive was applied between the facing and elastic layers. The layers and adhesive were nipped between a pair of nip rollers at a nip force of 44 Newtons per linear centimeter (N/cm) (25 pounds per linear inch) and the laminate was then allowed to relax.
A visual inspection of the exposed surface of the facing layer indicated substantially no noticeable surface undulations. The exposed surface of the polyurethane film also had no noticeable surface undulations. Results from the physical testing are set forth in Table I.
ExamPle VI
In Example VI, as compared to Example IIa, the spacing between the Lycra~ monofilament yarns was decreased to approximately 3.2 mm (8 yarns per inch). All other aspects of the samples were the same including the degree of stretch (300%).
A visual inspection of the samples yielded the same observations as with the Example I. Results from the physical testing are set forth in Table I. As can be seen from the fluid barrier test results, the laminates of Example IIa did not provide as good a barrier seal as the laminate of Example VI. As a result, it is evident that a higher retraction force is advantageous with respect to providing an appropriate barrier seal.
Example VII
In Example VII the facing and elastic layers were the same as in Example I and the adhesive application rate was reduced from 10 gsm to 8 gsm. The backing layer was a 0.5 mil polyethylene film from Consolidated Thermoplastics of Schaumburg, Illinois and was designated LSF-22. The sample was prepared with 250 percent stretch in the elastic layer prior to attachment. Visual inspections resulted in the same observations as with Example I with respect to the exposed surfaces of the facing and backing layers. Results from the physical testing are set forth in Table I.
2~87~0 It is evident from the examples cited above and the results of the fluid barrier test that certain criteria must be met in terms of either the resistance to compression or the elastic force (i.e., elongation and retraction loads) of the high loft perimeter barrier seal material for adequate fluid barrier performance. A comparison of the fluid barrier performance of Sample IIa and Sample IIb, which differed only in resistance to compression, illustrated that minimal resistance to compression was necessary for good fluid barrier performance at lower elastic force. A comparison of Sample VI
with Sample IIa, which differed only in elongation and retraction load, illustrated that higher elastic force can be used to overcome the higher resistance to compression and to provide good fluid barrier properties. However, such higher elastic force can lead to greater discomfort to the user of the personal care absorbent article.
Having thus described the invention in detail it should be apparent that various modifications and changes can be made in the present invention without departing from the spirit and scope of the following claims.
with Sample IIa, which differed only in elongation and retraction load, illustrated that higher elastic force can be used to overcome the higher resistance to compression and to provide good fluid barrier properties. However, such higher elastic force can lead to greater discomfort to the user of the personal care absorbent article.
Having thus described the invention in detail it should be apparent that various modifications and changes can be made in the present invention without departing from the spirit and scope of the following claims.
Claims (12)
1. A fibrous nonwoven elastic laminate comprising:
a high loft nonwoven facing layer containing a plurality of fibers having average fiber diameters of from about 15 to about 30 microns, said high loft nonwoven facing layer having a basis weight of from about 17 to about 180 grams per square meter, a density of 0.03 grams per cubic centimeter or less and a bulk of 0.67 millimeters or greater at 6,900 dynes/cm, a backing layer having a density greater than said high loft nonwoven facing layer and a lower bulk than said high loft nonwoven facing layer, and an elastic layer positioned between and tensionally attached to said high loft nonwoven facing layer and said backing layer to form said laminate.
a high loft nonwoven facing layer containing a plurality of fibers having average fiber diameters of from about 15 to about 30 microns, said high loft nonwoven facing layer having a basis weight of from about 17 to about 180 grams per square meter, a density of 0.03 grams per cubic centimeter or less and a bulk of 0.67 millimeters or greater at 6,900 dynes/cm, a backing layer having a density greater than said high loft nonwoven facing layer and a lower bulk than said high loft nonwoven facing layer, and an elastic layer positioned between and tensionally attached to said high loft nonwoven facing layer and said backing layer to form said laminate.
2. The laminate of claim 1 wherein at least a portion of said plurality of fibers in said high loft nonwoven facing layer are bicomponent fibers.
3. The laminate of claim 1 wherein said backing layer is a fibrous nonwoven web.
4. The laminate of claim 1 wherein said backing layer is a film.
5. The laminate of claim 1 wherein said elastic layer comprises elastic yarns.
6. The laminate of claim 1 wherein said elastic layer comprises an elastic film.
7. A personal care absorbent article which includes the laminate of claim 1 for the purpose of fluid containment.
8. The personal care absorbent article of claim 7 wherein said article is a diaper.
9. The personal care absorbent article of claim 7 wherein said article is a training pant.
10. The personal care absorbent article of claim 7 wherein said article is an incontinence garment.
11. The personal care absorbent article of claim 7 wherein said article is a sanitary napkin.
12. The personal care absorbent article of claim 7 wherein said article is a bandage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US31618594A | 1994-09-30 | 1994-09-30 | |
| US08/316,185 | 1994-09-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2158790A1 true CA2158790A1 (en) | 1996-03-31 |
Family
ID=23227899
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2158790 Abandoned CA2158790A1 (en) | 1994-09-30 | 1995-09-21 | Perimeter barrier seal for personal care absorbent articles and the like |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2158790A1 (en) |
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| WO2019152974A1 (en) * | 2018-02-05 | 2019-08-08 | Berry Global, Inc. | Lofty nonwoven fabrics |
| WO2019169989A1 (en) * | 2018-03-06 | 2019-09-12 | The Procter & Gamble Company | Wearable article comprising an elastic laminate |
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-
1995
- 1995-09-21 CA CA 2158790 patent/CA2158790A1/en not_active Abandoned
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
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