|5914084||Method of making a stabilized extensible nonwoven web||1999-06-22||Benson et al.|
|5910225||Film and nonwoven laminate and method||1999-06-08||McAmish et al.|
|5910224||Method for forming an elastic necked-bonded material||1999-06-08||Morman|
|5910136||Oriented polymeric microporous films with flexible polyolefins||1999-06-08||Hetzler et al.|
|5883028||Breathable elastic film/nonwoven laminate||1999-03-16||Morman et al.|
|5865926||Method of making a cloth-like microporous laminate of a nonwoven fibrous web and thermoplastic film having air and moisture vapor permeabilities with liquid-barrier properties||1999-02-02||Wu et al.|
|5865823||Absorbent article having a breathable, fluid impervious backsheet||1999-02-02||Curro|
|5861074||Method of making an elastic laminated sheet of an incrementally stretched nonwoven fibrous web and elastomeric film||1999-01-19||Wu|
|5855999||Breathable, cloth-like film/nonwoven composite||1999-01-05||McCormack|
|5853881||Elastic laminates with improved hysteresis||1998-12-29||Estey et al.|
|5843066||Absorbent article having a breathable backsheet||1998-12-01||Dobrin|
|5843057||Film-nonwoven laminate containing an adhesively-reinforced stretch-thinned film||1998-12-01||McCormack|
|5843056||Absorbent article having a composite breathable backsheet||1998-12-01||Good et al.|
|5837352||Mechanically compatibilized film/nonwoven laminate||1998-11-17||English et al.|
|5814390||Creased nonwoven web with stretch and recovery||1998-09-29||Stokes et al.|
|5789065||Laminated fabric having cross-directional elasticity and method for producing same||1998-08-04||Haffner et al.|
|5695868||Breathable, cloth-like film/nonwoven composite||1997-12-09||McCormack|
|5695849||Elastic, breathable, barrier fabric||1997-12-09||Shawver et al.|
|5688157||Nonwoven fabric laminate with enhanced barrier properties||1997-11-18||Bradley et al.|
|5681645||Flat elastomeric nonwoven laminates||1997-10-28||Strack et al.|
|5592690||Elastic laminated sheet for articles of clothing||1997-01-14||Wu|
|5571096||Absorbent article having breathable side panels||1996-11-05||Dobrin et al.|
|5569234||Disposable pull-on pant||1996-10-29||Buell et al.|
|5518801||Web materials exhibiting elastic-like behavior||1996-05-21||Chappell et al.|
|5514470||Composite elastic necked-bonded material||1996-05-07||Haffner et al.|
|5509142||Raised arm coveralls||1996-04-23||Connell et al.|
|5422172||Elastic laminated sheet of an incrementally stretched nonwoven fibrous web and elastomeric film and method||1995-06-06||Wu|
|5382461||Extrusion laminate of incrementally stretched nonwoven fibrous web and thermoplastic film and method||1995-01-17||Wu|
|5336545||Composite elastic necked-bonded material||1994-08-09||Morman|
|5226992||Process for forming a composite elastic necked-bonded material||1993-07-13||Morman|
|5167897||Method for incrementally stretching a zero strain stretch laminate web to impart elasticity thereto||1992-12-01||Weber et al.|
|5156793||Method for incrementally stretching zero strain stretch laminate web in a non-uniform manner to impart a varying degree of elasticity thereto||1992-10-20||Buell et al.|
|5151092||Absorbent article with dynamic elastic waist feature having a predisposed resilient flexural hinge||1992-09-29||Buell et al.|
|5143679||Method for sequentially stretching zero strain stretch laminate web to impart elasticity thereto without rupturing the web||1992-09-01||Weber et al.|
|5116662||Multi-direction stretch composite elastic material||1992-05-26||Morman|
|5114781||Multi-direction stretch composite elastic material including a reversibly necked material||1992-05-19||Morman|
|4981747||Composite elastic material including a reversibly necked material||1991-01-01||Morman|
|4965122||Reversibly necked material||1990-10-23||Morman|
|4834741||Diaper with waist band elastic||1989-05-30||Sabee|
|4833172||Stretched microporous material||1989-05-23||Schwarz et al.|
|4789699||Ambient temperature bondable elastomeric nonwoven web||1988-12-06||Kieffer et al.|
|4725481||Vapor-permeable, waterproof bicomponent structure||1988-02-16||Ostapchenko|
|4657802||Composite nonwoven elastic web||1987-04-14||Morman|
|4539256||Microporous sheet material, method of making and articles made therewith||1985-09-03||Shipman|
|4153751||Process for stretching an impregnated film of material and the microporous product produced thereby||1979-05-08||Schwarz|
|4153664||Process for pattern drawing of webs||1979-05-08||Sabee||264/288.8X|
|4116892||Process for stretching incremental portions of an orientable thermoplastic substrate and product thereof||1978-09-26||Schwarz|
|3989867||Absorptive devices having porous backsheet||1976-11-02||Sisson|
|3881489||Breathable, liquid inpervious backsheet for absorptive devices||1975-05-06||Hartwell|
|3156342||Rivet feed machines||1964-11-10||Brewer|
|3156242||Flexible absorbent sheet||1964-11-10||Crowe|
|EP0810078||1997-12-03||Method for making fluid distribution materials|
|WO1998028134A1||1998-07-02||LAMINATION OF BREATHABLE FILM USING A RUBBER-COVERED ANVIL ROLL|
|WO1998029246A1||1998-07-09||BREATHABLE LAMINATE OF NONWOVEN AND ELASTOMERIC FILM INCLUDING METALLOCENE CATALYZED POLYETHYLENE ELASTOMER AND METHOD FOR MAKING THE SAME|
|WO1998029247A1||1998-07-09||IMPROVED CLOTH-LIKE, LIQUID-IMPERVIOUS, BREATHABLE COMPOSITE BARRIER FABRIC|
|WO1998029479A1||1998-07-09||ELASTOMERIC FILM INCLUDING METALLOCENE CATALYZED POLYETHYLENE ELASTOMER AND METHOD FOR MAKING THE SAME|
|WO1998029480A1||1998-07-09||MICROPOROUS ELASTOMERIC FILM/NONWOVEN BREATHABLE LAMINATE AND METHOD FOR MAKING THE SAME|
|WO1999012734A1||1999-03-18||BREATHABLE, LIQUID-IMPERMEABLE, APERTURED FILM/NONWOVEN LAMINATE|
|WO1999014039A1||1999-03-25||ELASTIC FILM LAMINATES|
|WO1999014044A1||1999-03-25||BREATHABLE ELASTIC FILM AND LAMINATE|
|WO1999014262A1||1999-03-25||STABLE BREATHABLE ELASTIC ARTICLES|
|WO1999014263A1||1999-03-25||PROCESS FOR MAKING MICROPOROUS FILMS|
The present invention relates to disposable absorbent articles. More particularly, the invention relates to an economical method for advantageously modifying the physical properties of a nonwoven fibrous web for use as a component of a disposable absorbent article, and to disposable articles incorporating such modified nonwoven webs.
Disposable, wearable articles having an inner, body-facing, absorbent, liquid-retaining component and an outer, garment-facing, liquid-impervious component are well known. Articles of that type are commonly available in the form of disposable diapers, disposable underwear, pull-on diapers and training pants, incontinence pads, incontinence briefs, sanitary napkins, and the like. Such articles generally include a flexible, liquid-impervious backsheet that is adapted to be positioned between an absorbent component of the article and the clothing of the wearer, to prevent wetting or soiling of the wearer's clothing when the article is in use.
In addition to imperviousness to liquids, the backsheet also preferably includes a cloth-like outer surface, which provides a softer feel, and also a more appealing visual appearance, as compared with the outer surface of a smooth, flat plastic film. Two-ply backsheets that provide a desirable, more cloth-like appearance for such disposable, wearable articles are also known. In that regard, U.S. Pat. No. 5,151,092, entitled “Absorbent Article with Dynamic Elastic Waist Feature Having a Predisposed Resilient Flexural Hinge,” which issued on Sep. 29, 1992, to Kenneth B. Buell, et al., discloses a disposable diaper backsheet formed either from a woven or a nonwoven material, a polymeric film, or a composite material in the form of a film-coated, nonwoven material. That patent also discloses the step of embossing of a plastic film backsheet to provide a more cloth-like visual appearance to a plastic film.
Also known to those skilled in the art are methods for imparting stretchability to an otherwise substantially inelastic material, which may be employed as a backsheet. For example, the use of corrugating rolls to laterally or longitudinally stretch and to simultaneously provide a corrugated form to thin plastic films is disclosed in U.S. Pat. No. 4,116,892, entitled “Process for Stretching Incremental Portions of an Orientable Thermoplastic Substrate and Product Thereof,” which issued on Sep. 26, 1978, to Eckhard C. A. Schwarz; U.S. Pat. No. 4,834,741, entitled “Diaper With Waistband Elastic,” which issued on May 30, 1989, to Reinhardt N. Sabee; U.S. Pat. No. 5,156,793, entitled “Method for Incrementally Stretching Zero Strain Stretch Laminate Sheet In A Non-Uniform manner To Impart A Varying Degree Of Elasticity Thereto,” which issued on Oct. 20, 1992, to Kenneth B. Buell et al.; U.S. Pat. No. 5,167,897, entitled “Method for Incrementally Stretching A Zero Strain Stretch Laminate Sheet To Impart Elasticity Thereto,” which issued on Dec. 1, 1992 to Gerald M. Sheeter et al.; and U.S. Pat. No. 5,422,172, entitled “Elastic Laminated Sheet of An Incrementally Stretched Nonwoven Fibrous Sheet and Elastomeric Film and Method,” which issued on Jun. 6, 1995, to Pai-Chuan Wu. The corrugating rolls disclosed in each of those patents are employed in carrying out a process sometimes referred to as “ring-rolling,” to locally stretch and form corrugations in the material, in order to impart a greater degree of stretchability to selected portions of a sheet or web that may serve as a backsheet for disposable absorbent articles. Such backsheets can include both a polymeric film and an overlying and contacting layer of nonwoven, fibrous material.
In addition to incorporation into backsheets, nonwoven materials can also be incorporated into and form a part of a liquid-pervious topsheet, as well as in leg cuffs that are provided to minimize leakage from the article. Other structural members of disposable absorbent articles can also include nonwoven elements, particularly where stretchability of the material is a desirable attribute for providing improved fit of the article.
In order to provide improved comfort to the wearer of disposable absorbent articles, certain components of the articles, such as a backsheet, in addition to providing imperviousness to liquids, desirably permit the passage therethrough of moisture vapor and also preferably air, to help maintain dryness and to reduce the humidity adjacent the wearer's body. An impervious polymeric film to which breathability has been imparted to allow air and moisture vapor transmission through the film is disclosed U.S. Pat. No. 3,156,342, entitled “Flexible Absorbent Sheet,” which issued on Nov. 10, 1964, to G. A. Crowe, Jr.; U.S. Pat. No. 3,881,489, entitled “Breathable, Liquid Impervious Backsheet for Absorbent Devices,” which issued on May 6, 1975 to Edward Wallace Hartwell, et al.; U.S. Pat. No. 3,989,867, entitled “Absorbent Devices Having Porous Backsheet,” which issued on Nov. 2, 1976, to James Bryant Sisson; U.S. Pat. No. 4,153,751, entitled “Process for Stretching an Impregnated Film of Material and The Microporous Product Produced Thereby,” which issued on May 8, 1979, to Eckhard C. A. Schwarz; and U.S. Pat. No. 4,539,256, entitled “Microporous Sheet Material, Method of Making and Articles Made Therewith,” which issued on Sep. 3, 1985, to Gene H. Shipman.
Although there have been significant product improvements in recent years that have resulted in improved functioning and increased consumer acceptance of disposable absorbent articles, it is still desirable to provide an economical way to form for use in such articles a stretchable nonwoven material having optimal physical properties, which may for example be employed in a backsheet that is impervious to liquids, that is pervious to moisture vapor and also preferably air, and that additionally has a soft, cloth-like outer surface.
Accordingly, it is an object of the present invention to provide an economical method for advantageously modifying a pre-formed, nonwoven fibrous web to have desirable properties which can be used as a component or an extensible component of a disposable absorbent article.
It is another object of the present invention to provide a method for making a relatively inexpensive, flexible composite material which can be used in a disposable absorbent article, wherein the composite material may include the attribute of liquid-imperviousness, and the desirable attribute of perviousness to moisture vapor and also preferably air, as well as the desirable attribute of a soft, cloth-like feel on at least one of its surfaces.
It is a further object of the present invention to provide a method for economically modifying a pre-formed, nonwoven fibrous web and joining it to an elastic component to create a composite material which can be advatageously used as a elastically stretchable, and if desired breathable, component of a disposable absorbent article.
Briefly stated, in accordance with one aspect of the present invention, an economical method is provided for advantageously modifying the physical characteristics of a pre-formed, nonwoven fibrous web. The method includes feeding in a web movement direction to a pair of opposed forming rolls a substantially untensioned, nonwoven fibrous web having an initial width, thickness, basis weight, low-elongation cross-web extensibility expressed as an initial load to achieve 10% cross-web elongation, intermediate-elongation cross-web extensibility expressed as an initial load to achieve 30% cross-web elongation, cross-web strength, and elongation capability. The web is gripped between the forming rolls at a nip defined by the forming rolls. Each forming roll includes a plurality of axially spaced, circumferentially extending, alternating radial teeth and intervening grooves that are in interengaged condition, with the teeth of each roll extending into the grooves of the opposed roll.
The gripped nonwoven web is subjected to incremental lateral stretching by passing the web between the interengaged forming rolls while the rolls are rotating in opposite directions to incrementally stretch the web in a lateral, cross-web (i.e., “cross-machine” or CD) direction that is substantially perpendicular to the longitudinal, web movement (i.e., “machine” or MD) direction. The incrementally stretched web is then withdrawn from between the forming rolls by applying to the stretched web a substantially uniform tensile force in the web movement direction as the web passes from the forming rolls, to stretch the web in the web movement direction to obtain a modified web which has a load to achieve 10% cross-web elongation of from about 5% to about 100% of the initial load to achieve 10% cross-web elongation, a load to achieve 30% cross-web elongation of from about 5% to about 100% of the initial load to achieve 30% cross-web elngation, a cross-web strength of from about 10% to about 80% of the initial cross-web strength, and an elongation capability of from about 105% to about 200% of the initial cross-web elongation capability. The web may also have a modified web width that is from about 25% to about 300% of the initial web width, a modified web thickness that is from about 85% to about 400% of the initial web thickness, and a modified basis weight that is less than, equal to, or greater than the initial web basis weight.
In accordance with another aspect of the present invention, a method is provided for combining a modified nonwoven fibrous web of the invention with a polymeric film, or with an elastic member, which may be liquid-impervious, yet breathable.
In accordance with still another aspect of the present invention, a method is provided for making a liquid-impervious, breathable material which can be used, for example, as a backsheet for a disposable absorbent article having a soft, cloth-like, outermost surface. The method includes providing a nonwoven fibrous web having its physical properties modified by having passed through a pair of forming rolls. A thermoplastic polymeric film is provided that includes an incompatible inorganic material dispersed therewithin to provide a plurality of discrete, spaced regions of inorganic material within a polymer matrix. The polymeric film includes a first face and a second face. The modified fibrous nonwoven web is then combined with the polymeric film to form a composite web, wherein the second face of the polymeric film defines an outwardly-facing surface of the composite web. The composite web is then passed between a pair of opposed, closely spaced forming rolls each having a plurality of alternating teeth and grooves that are in intermeshing relationship. The forming rolls impart cross-web tensile forces to the composite web, which provides micropores within the polymeric film as a result of localized stretching of the film to cause localized separation of the thermoplastic polymer from the incompatible material to provide the micropores. The micropores so provided are of a size that permits the passage through the composite web of air and moisture vapor but substantially prevents the passage therethrough of liquids.
The present invention also includes the soft, cloth-like, liquid-impervious and breathable backsheets, and other absorbent article components, such as topsheets, cuffs and other structural members that are formed by incorporating a nonwoven fibrous web that has been modified in accordance with the methods herein described.
The present invention is directed to the modification of the physical properties, and if desired the dimensions, of nonwoven material intended for use in disposable absorbent articles. After modification, the nonwoven material can, if desired, be joined with other materials for incorporation as functional and structural elements of disposable absorbent articles. Examples of such other materials include liquid-impervious films yet breathable films, precursor films that can be made to be breathable, elastomeric films, and the like. Although disclosed herein in the context of use with disposable articles, it will be apparent to those skilled in the art that such modified nonwoven materials also can be employed in other structures intended for other uses.
As used herein, the term “nonwoven” refers to a fibrous web or sheet that has a structure of individual fibers or threads that are interlaid, but not in any regular, repeating manner. Nonwoven sheets have in the past been formed by a variety of processes, such as meltblowing processes spunbonding processes, and bonded carded processes.
As used herein, the term “extensible” refers to any material that upon application of a biasing force is stretchable, or that is elongatable by at least about 50% (i.e., having a stretched, biased length that is at least about 150% of its relaxed, unbiased length).
As used herein, the term “polymer” generally includes, but is not limited to, homopolymers, copolymers, such as block, graft, random, and alternating copolymers, terpolymers, and the like, and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” includes all possible molecular geometric configurations of the polymeric material. Such configurations include, but are not limited to, isotactic, syndiotactic, and random symmetries.
As used herein, the term “elastic” refers to any material that, upon application of a biasing force, is stretchable, that is, elongatable, to at least about 50% (i.e., to a stretched, biased length, which is at least about 150% of its relaxed unbiased length), and which, will recover at least about 50% of its elongation upon release of the stretching, elongation force.
As used herein, the term “composite elastic material” refers to a material that includes an elastic material component that is joined to an extensible material component. The elastic component can be joined to the extensible component at spaced, intermittent points or it can be continuously bonded thereto. The joinder of the components is accomplished while the elastic member and the extensible material are in juxtaposed position. The composite elastic material thus formed is also elastic. A composite elastic material can include more than the two layers described, if desired.
As used herein, the term “elongation capability” refers to the degree to which any material can be stretched, either in the web movement direction or in the cross-web direction, when a tensile biasing force is applied to the material without catastrophic failure of the material. The stretch is expressed herein as a percent (%), and is based upon the original, unstretched length and the stretched length immediately before rupture or failure of the material.
As used herein, the term “load to elongate” refers to the biasing force that must be applied to any material to elongate it to a given elongation, either in the web movement direction or in the cross-web direction, wherein the elongation is expressed as a percent (%), and is based upon the original, unstretched length and the stretched length.
As used herein, the term “surface-pathlength” refers to a measurement along a topographic surface of a material in a specified direction.
Referring now to the drawings, and particularly to
Although the ensuing discussion is based upon nonwoven materials in web form for high-speed production purposes, the nonwoven materials, as well as other materials to which the nonwoven materials are joined, can also be provided in the form of generally rectangular, discrete sheets of interengaged fibers, both before and after modification in accordance with the present invention. Thus, as used herein, the word “web” is intended to encompass such discrete sheets.
A nonwoven web of the type contemplated herein is in substantially flat form and is formed from a plurality of interengaged fibers. The web has a longitudinal axis that extends along the web movement or “machine” (MD) direction of the web, and a transverse axis that extends in the cross-web or “cross-machine” (CD) direction of the web. The interengaged fibers define a relatively thin, coherent, self-supporting structure. The fibers can be loosely interengaged, without bonds connecting adjacent fibers, or they can be bonded to each other or otherwise connected with other such fibers by suitable connection elements, such as adhesives, or the like, or adjacent fibers can be at least partially melt bonded to each other.
A preferred material for web
Suitable nonwoven webs can be made from 100% polyethylene fibers, either linear, low-density polyethylene or high-density polyethylene. Included among such suitable and preferred nonwoven materials is a spunbonded material that is known commercially as 13561A, and which is available from FiberWeb North America, Inc., of Simpsonville, S.C.
The preferred nonwoven, fibrous web materials can have an initial thickness of from about 5 mils to about 40 mils, preferably of from about 10 mils to about 20 mils. Additionally, the preferred webs can have an initial basis weight of from about 10 gm/m
Referring again to
The spaces between adjacent teeth
Although the portions of web
The action of pressing of portions of web
Because of the localized cross-web stretching of web
If the nonwoven web is expanded only in the X-Y plane there will be a substantial decrease in the basis weight of the nonwoven web, which serves to reduce the cost of any components of which the rolled nonwoven web is a part. Preferably, for a fibrous nonwoven web in accordance with tire present invention, the width of the modified web is about 100% greater than its initial width before it is passed through the forming rolls. On the other hand, if the web movement direction tension on the web as it leaves the forming rolls is sufficiently high, the modified web will have a width that is less than its original width, and a greater basis weight than that of the original, unmodified web.
But if the exiting, modified nonwoven web retains the sinusoidal cross-sectional form shown in
Referring now to
In the embodiment shown in
In addition to the surface patterns illustrated in
As shown in
Another set of forming rolls, having a different arrangement of the peripheral teeth and grooves and that can be utilized in the practice of the present invention, is shown in
Reference numerals that identify the various parameters of the teeth and grooves of the several forming roll configurations illustrated herein are shown in
As was noted earlier herein, in addition to modifying the dimensions of a nonwoven web by extending the web, for example, in the X-Y plane to lower its basis weight, and by adding loft to the web in the Z direction to impart surface softness and cloth-like appearance, the present invention is also directed to modifying the physical properties of the nonwoven web in a beneficial way. As used herein the term “physical properties” refers to the performance characteristics of the web, including the strength of the Web when subjected to a tensile force, its elongation capability when subjected to a tensile force, and the force needed to elongate the web to a point short of tearing or rupture of the web material. Those desirable physical property modifications can be provided by passing the nonwoven web through at least one pair of the interengaged forming roll structures that have been described earlier herein, applying at least some degree of web-movement direction tension and, if desired, applying additional cross-web direction stretching as described previously. Additionally, the present invention also encompasses successive modifications of the nonwoven web by passing the web through successive sets of forming rolls, tensioning and, if desired, additional cross-web direction stretching. For example, a first set of forming rolls can serve to increase the elongation capability of the nonwoven web without causing shredding of the web into “pieces” or “strips,” and a second set of forming rolls can serve to expand the web in the X-Y plane.
For some of the composite structural components that are incorporated in a disposable absorbent article and that include nonwovens, it is desirable that the cross-web (CD) strength of the modified nonwoven web be substantially lower than that of an unmodified web. For other components the cross-web elongation capability of a modified web is desirably substantially higher than that of an unmodified web, or the load to elongate is substantially lower, as compared with typical values attainable from commercially available, unmodified nonwoven webs that are made using either a carded, a spunbonded, or a spunbond/meltblown process. In that regard, it is desirable that a modified nonwoven web in accordance with the present invention exhibit a load to achieve 10% cross-web elongation of from about 5% to about 100% of the corresponding cross-web elongation load of the unmodified nonwoven web, that it exhibit a load to achieve 30% cross-web elongation of from about 5% to about 100% of the corresponding cross-web elongation load of the unmodified nonwoven web, and that it exhibit a cross-web elongation capability of from about 105% to about 200% of the cross-web elongation capability of the unmodified nonwoven web.
For example, a modified nonwoven web can be utilized as a component of a composite, breathable backsheet, one that is liquid impervious but that is pervious to gases and moisture vapor and that preferably has at least one soft, cloth-like outer surface. However, when utilized in such a composite structure it is highly advantageous that the modified nonwoven component of such a backsheet have a substantially lower CD tensile strength, that it be capable of elongation at lower CD tensile loads, and that it be capable of higher elongation. The provision of such physical characteristics in a modified nonwoven web prior to its attachment to a polymeric film enables the resulting composite nonwoven-film structure to be incrementally stretched at lower tensile forces, and without the formation of undesirable tears or large openings in the nonwoven element of the composite. Such a composite backsheet can thus more easily be conformed with and adapt to the contours of the body of a wearer of a disposable article, both during application of the article to the body as well as while being worn and being subjected to loads as a result of body movements of the wearer. The improved fit and adaptability to changing wearing conditions leads to greater wearer comfort.
Presented in Table I below and identified by Example numbers 1 through 7 are the physical property changes that resulted from the modification of three different nonwoven web materials by passing the webs between interengaged forming rolls having a particular tooth structure and size. The material for Examples 1 and 2 was a carded nonwoven that is identified by No. 16006942, obtained from FiberWeb North America, of Simpsonville, N.C. The material for Examples 3 and 4 was a composite, three-layer web of nonwoven materials (designated “SMS” in Table I) identified as Style No. 81350, obtained from PolyBond Company, of Waynesboro, Va., wherein the composite material included an inner layer of a meltblown nonwoven and outer layers of a spunbonded nonwoven overlying each of the faces of the inner layer. The material for Examples 5 through 7 was a spunbonded nonwoven material identified by No. 13561A and was also obtained from FiberWeb North America.
For each of the nonwoven starting materials, Table I identifies the type of nonwoven material, the initial basis weight, the initial strength to rupture, and the initial elongation characteristics, along with the initial web thickness. Table I also shows the results on each of the starting nonwoven materials of physical modification by passing the materials between opposed pairs of differently configured, interengaged forming rolls in accordance with the present invention.
|Forming||CD||CD Elongation||CD Load To||CD Load To|
|Example||Starting Material||Roll||Strength||Capability||Elongate 10%||Elongate 30%||Thickness|
|27 gsm carded||Starting mat'l.||1564||233||13||19||10|
|2||Fiber Web NA||“B”||1641||265||7||10||30|
|25 gsm SMS||Starting mat'l.||3038||118||45||87||9|
|33 gsm Spun||Starting mat'l.||3186||250||22||41||10|
|6||Fiber Web NA||“B”||2735||282||8||13||42|
Table II below sets forth the tooth and groove configurations and sizes for the several types of interengaged forming rolls (A, B, and C) that were employed in modifying the respective initial nonwoven webs to provide the examples of modified nonwoven webs that are identified in Table I. Forming rolls A of Table II have the external configurations shown in the respective upper and lower rolls as illustrated in
|Forming Roll Description & Conditions|
|(in.) - 160|
|(in.) - 156|
|(in.) - 166|
|MD Band Spacing||—||—||—||0.360||—|
|MD Band Width||—||—||—||0.060||—|
|(in.) - 164|
|CD Band Width||—||0.1250||—||0.060||—|
|(in.) - 170|
|Tooth Tip Radius||0.005||0.005||0.005||0.005||0.005|
|Tooth End Radius||—||0.0938||—||0.0938||—|
|MD Web Tension||<0.2||<0.2||0.2-0.5|
Examples 1 and 2 listed in Table I show the physical properties of a modified carded nonwoven web that result from passing the web between forming rolls having tooth structures and tooth sizes as listed under the designations A and B, respectively, in Table II. The web having the physical characteristics corresponding with Example 1 in Table I was formed by passing the initial carded nonwoven web between a pair of forming rolls having the configurations illustrated in FIG.
Examples 3 and 4 listed in Table I show the physical properties of a modified composite web of nonwoven materials, including layers of spunbonded/meltblown/spunbonded (SMS) materials, that results from passing the web between forming rolls having tooth structures and tooth sizes as listed under the designations A and B in Table II. The web having the physical characteristics corresponding with Example 3 in Table I was formed by passing the initial composite web of nonwoven materials between a pair of forming rolls having the configuration illustrated in FIG.
Examples 5, 6, and 7 listed in Table I show the physical properties of a modified spunbonded nonwoven web that results from passing the web between forming rolls having tooth structures and tooth sizes as listed under the designations A, B, and C in Table II. The web having the physical characteristics corresponding with Example 5 in Table I was formed by passing the initial spunbonded nonwoven web between a pair of forming rolls having the configurations shown in FIG.
In connection with the physical characteristics of the respective modified nonwoven web materials identified in Table I, it is significant to note the changes in cross-web direction (CD) strength of the modified nonwovens. With the exception of the carded nonwoven material represented by Examples 1 and 2, the CD strength of each of the nonwoven webs decreased considerably as a result of the modification of the nonwoven material in accordance with the present invention. The CD strength decrease was greatest for the SMS material, ranging between 35.2% to 63.7%, while for the spunbonded nonwoven material it ranged between 14.2% to 43%. For the SMS material the CD strength decrease was greatest when the material was passed between forming rolls having the configuration illustrated in
The CD elongation capability of the nonwoven materials also increased for each of the materials, regardless of the forming roll configuration through which the nonwoven materials were passed. The greatest increase was, again, obtained when the materials were passed between forming rolls having the configuration illustrated in FIG.
Finally, and again except for the carded nonwoven, the CD load to elongate by either 10% or 30% was remarkably reduced for the modified nonwoven materials that were subjected to the rolling procedures described herein. For both the SMS nonwoven material as well as the spunbonded material the CD load to elongate was reduced by from about 68% to about 85%. It can thus be seen that the physical properties of the respective nonwoven materials have been substantially altered after the nonwoven webs have passed between the forming rolls.
It will be appreciated by those skilled in the art that although the present disclosure has made reference to the use of grooved rolls, grooved plates can also be employed to carry out the method herein disclosed. In that regard, the disclosure in the previously-cited and previously-incorporated U.S. Pat. No. 5,518,801, Chappell et al., illustrates and describes a pair of flat plates having intermeshing teeth, and that can be utilized to effect the lateral extension of a flexible web or of polymeric material in the manner hereinbefore described. Similarly, although sometimes illustrated and described herein in the context of a continuous, moving web of material, the method herein disclosed can also be practiced utilizing materials in sheet form.
Furthermore, although the foregoing discussion has been presented in the context of modifying a nonwoven by local expansion of the material in the width dimension of a web, the benefits of the present invention can also be obtained by local expansion of the length (MD) dimension of such webs, instead of the width (CD) dimension. In that instance the forming rolls can have axially-extending teeth and grooves on their peripheral surfaces, rather than teeth and grooves that extend transversely of the roll longitudinal axis as shown in the forming roll structure illustrated in
Modified nonwoven materials of the types represented by Examples 1 through 7 of Table I can be incorporated into various kinds of disposable absorbent articles, such as disposable diapers. As will be hereinafter described in greater detail, those materials can serve as the outer surface of a backsheet of such articles, as a topsheet, or as part of a stretchable component that has at least one soft, outer, cloth-like surface.
One example of a structural component of a disposable absorbent article with which a modified nonwoven web of the type hereinabove described can be utilized is the backsheet. That component is generally the outermost component of the article and provides imperviousness to the passage through the article of liquid body fluids or exudates that are intended to be absorbed by and retained in an inner, absorptive component of the article. A nonwoven modified in accordance with the present invention can be joined to one surface of a solid, liquid-impervious, polymeric film to provide a soft, cloth-like outer surface to the backsheet and to the article. Another embodiment of a backsheet can be provide desirable imperviousness to the passage of liquids, while permitting passage therethrough moisture vapor and also preferably air. A backsheet having those characteristics is preferably flexible, compliant, and has the desired soft, cloth-like outer surface, and can include a breathable polymeric film that is substantially impervious to liquids but pervious to moisture vapor and also preferably air.
Referring once again to
A particularly suitable film
Instead of a liquid-impervious and non-breathable film, as is frequently employed as a part of the backsheet of disposable diapers, or films that are substantially liquid-impervious but breathable as supplied, polymeric film
Breathability can be imparted to a polymeric film, while maintaining its imperviousness to liquids, by forming micropores in the film. The desired micropores are sufficiently small in area to prevent the passage therethrough of liquids, but they allow the passage therethrough of air and moisture vapor. Micropores can be formed directly in an otherwise solid film in several ways, including perforating the film as disclosed in U.S. Pat. No. 3,881,489, entitled “Breathable, Liquid Impervious Backsheet for Absorbent Devices”, which issued on May 6, 1975, to Edward Wallace Hartwell. Perforations can be provided by mechanically puncturing the film, but that technique requires close tolerance control over the puncturing elements of the apparatus, which over time might provide micropores of increasingly greater size as a result of mechanical wear of the puncturing elements. Larger micropores could allow the undesired passage of liquids through such films.
Another way to enable the formation of micropores in an otherwise impervious film involves substantially uniformly dispersing within a thermoplastic polymer matrix an incompatible inorganic or organic material. The dispersion of the incompatible material can be effected by a mixing step, and the resulting mixture can be formed into a thin film by extruding, casting, or blowing techniques that are known to those skilled in the art. As used herein, the term “incompatible” as applied to the inorganic or organic materials means materials that are incapable of being dissolved in the polymer, so that those materials retain their original form and composition and remain separate and distinct from, but are surrounded by, the polymer matrix. Formation of the micropores is effected after the film has been formed, by locally stretching the precursor film in a manner that will be described in greater detail hereinafter.
An example of an organic material that can be mixed with the thermoplastic polymer to permit the attainment of breathability of the film by post-film-formation processing is mineral oil, as disclosed in U.S. Pat. No. 4,609,584, entitled “Absorptive Devices,” which issued on Sep. 2, 1986, to Cutler et al., the disclosure of which is incorporated herein by reference.
Examples of inorganic materials that can be mixed with the thermoplastic polymer to permit the attainment of breathability of the film by post-film-formation processing are calcium carbonate, clay, titanium dioxide, and mixtures thereof. Calcium carbonate is a preferred inorganic material from the standpoints of relatively low cost and of ready commercial availability. Preferably, the inorganic material is supplied in particulate form, having a particle size ranging from about 1 to about 5 microns, and it can constitute from about 5 to about 70 percent by weight of the polymer-particulate mixture. The inorganic material can optionally be coated with a fatty acid ester to enable higher loadings of the inorganic material to be included in the polymer-inorganic mixture. Suitable other inorganic materials are disclosed in U.S. Pat. No. 4,472,328, entitled “Process for Producing Porous Film or Sheet,” which issued on Sep. 18, 1984, to Sugimoto et al., and in U.S. Pat. No. 4,777,073, entitled “Breathable Films Prepared From Melt Embossed Polyolefin/Filler Precursor Films,” which issued on Oct. 11, 1988, to Sheth, the disclosures of each of which patents are incorporated herein by reference.
Mixing of the inorganic material and the thermoplastic polymer can be effected in any suitable mixing device, such as a mixing extruder, to obtain a substantially uniform mixture of the components. Preferably, the inorganic material is substantially uniformly dispersed throughout the polymeric material. A flexible precursor film having a thickness of the order of from abut 0.3 mils to about 5 mils can be formed from such a mixture using known film forming equipment and techniques. Before undergoing a breathability-imparting process, the polymer-particulate precursor film typically has an initial moisture vapor transmission rate (MVTR) of less than about 100 g/m
In carrying out a method of making a composite, breathable, cloth-like backsheet in accordance with the present invention, breathability can be imparted to precursor film
When a precursor film is passed between forming rolls having roll surface configurations of any of the types previously described herein, sufficient localized stretching of the precursor film results in the formation of micropores in the film. In that regard, and referring to
The micropores that are so developed by stretching precursor film
The distribution of open areas
The precursor material can be joined to the nonwoven material at joinder station
The joinder of a non-fibrous polymeric film with a fibrous nonwoven web to form a composite web can be effected by heating either or both of the web or film to its softening temperature, and then pressing the web and film together lightly so that the web and film adhere to each other sufficiently to form a coherent, unitary, composite web upon cooling. Pressing can be performed at joinder station
As a further variant of the method of joining a polymeric precursor material with a nonwoven web, a layer of polymeric precursor material can be extrusion coated onto one of the surfaces of the nonwoven web. In that instance, because of the elevated temperature of the polymeric material as it exits from an extruder (not shown) onto the nonwoven web, the extruded material is sufficiently tacky so that it adheres to at least portions of the surface of the nonwoven web. If the temperature of the extruded material is sufficiently high, some melting of surface fibers of the nonwoven web can also take place, which upon cooling provides an even stronger bond between the polymeric precursor material and the nonwoven web.
In an another method, a polymeric precursor film can be applied to a surface of the modified nonwoven web by vacuum lamination of the precursor film material onto the modified nonwoven web.
The resulting composite web structure can then be passed between a pair of opposed, interengaging forming rolls
Components such as backsheets for disposable absorbent articles preferably have moisture vapor transmission rates, dynamic fluid impact values, and desirably oxygen permeation rates that fall within preferred ranges. The test methods for determining the values of those parameters for particular materials are described below.
One measure of the breathability of a film or composite material is the perviousness of the film or composite to the passage of water vapor, reflected by the moisture vapor transmission rate (MVTR) of the film. In the case of disposable diapers, breathability can be imparted to, for example, a composite backsheet by the process hereinabove described, or by employing a film in the composite which already possesses such a quality, as also described hereinabove. In that regard, the MVTR of the composite material, such as a backsheet, is preferably from about 500 g/m
The MVTR can be determined by placing a quantity of a hydrophilic material, such as calcium chloride, into a non-porous, open-top vessel (not shown) having an outwardly-extending flange around the vessel opening. A portion of the material for which the MVTR is to be determined is placed in overlying relationship relative to the vessel opening and is in contact with the flange of the vessel to completely cover the open end of the vessel. An annular gasket and an annular retaining ring are then placed over the material to be tested and are securely clamped to the vessel flange by any convenient clamping arrangement, to tightly and completely seal the periphery of the vessel opening in order that transmission of air or moisture vapor can only occur through the material under test. The resulting assembly is then weighed to determine the initial weight of the vessel and its contents.
After the initial weight has been determined, the assembly is placed in a chamber having a constant temperature (40° C.) and a constant humidity (75% relative humidity). The vessel is maintained under those atmospheric conditions for a period of five (5) hours, after which it is removed from the chamber, wrapped tightly with an impervious film to prevent transfer of moisture into and out of the vessel, and is allowed to reach thermal equilibrium with the ambient atmosphere in which the weigh balance is located. Thermal equilibrium is achieved in about 30 minutes, after which the film overwrap is removed from the vessel, which is again weighed to determine the final weight of the vessel and its contents.
The MVTR is calculated by the following formula, which provides the MVTR in g/m
Another preferred attribute of a breathable film or a composite material is perviousness to the passage of air, which can be assessed by a test that measures the oxygen permeation rate. (OPR) of the material. When employed as a part of a component, such as a backsheet, of a disposable diaper, a breathable composite should preferably have an oxygen permeation rate of from about 2 m
The OPR can be determined by providing a glass chamber having a circular mouth of about 12 cm diameter and including an inlet valve. An oxygen probe is placed within the chamber and is connected with an oxygen monitor (such as Cat. No. H-04406-10, available form Cole Parmer Instrument Co., of Vernon Hills, Ill.). A sample of the material for which the oxygen permeation rate is to be measured is provided in the form of a circle having a diameter of about 12 cm, to correspond substantially with the diameter of a 12 cm circular sample disc of aluminum foil (Part No. 025-493, available from Mocon, of Minneapolis, Minn.). A circle having a diameter of 2.54 cm is cut from the aluminum foil sample disc and is placed against the sample of the material to be tested.
The two discs (foil side up) are clamped to the opening of the sample container. An annular rubber gasket is then placed against the sample of material, without covering the opening in the foil sample disc. A second open-ended glass chamber, also having an inlet valve, and having an open end of substantially the same size as the open end of the sample chamber, is placed against the gasket and over the sample chamber, and is clamped to the sample chamber so that the foil disc and the sample material disc are positioned between the closed chambers.
Using the inlet valves of the chambers, each of the glass chambers is clushed with nitrogen to provide an initial oxygen concentration of 0.1% within the sample chamber. The second glass chamber is then removed so that one side of the material to be tested is exposed to air (20.9% oxygen). The times required to reach each of a predetermined series of oxygen concentrations within the sample chamber are recorded. The oxygen concentration values at which the times are recorded are in increments of 0.5%. The permeation rate of oxygen through the sample can then be calculated using the following formula:
When imparting a limited degree of moisture vapor, and also preferably air perviousness to a component such as a backsheet, it is important that the imperviousness of the component to liquids is not significantly diminished. And in addition to the desired attributes of imperviousness to liquids and perviousness to moisture vapor and preferably air when a component such as a backsheet is under no-load conditions, it is also desirable that substantial liquid imperviousness of the component be maintained even when the absorbent article is subjected to impact loads. Such loads can be imposed, for example, on a diaper backsheet when a baby wearing the diaper abruptly goes from a standing to a sitting position. In that regard, it is preferred that the perviousness to liquids under impact conditions be less than about 10 g/m
Perviousness of a material under impact conditions can be assessed by a test the measures the dynamic impact value of the material. As referred to herein, the “dynamic impact value” of a material is a value that is based upon the impact energy an average 20 lb. baby will impart to a saturated diaper if he or she falls or abruptly shifts from a standing position to a sitting position. Essentially, the dynamic impact value is a measure of the quantity of liquid that penetrates through a material under impact conditions.
Determination of the dynamic impact value for a particular material can be made by applying to the material an impact load of 20 Joules (14.75 ft-lb.) over an area of about 13.5 in
A wet diaper is simulated by providing a circular pad
A breathable, cloth-like composite sheet that can be incorporated into a disposable absorbent article as a breathable backsheet was prepared in accordance with the method steps shown in block diagram form in FIG.
Both the initial nonwoven web
|Forming Roll Description & Conditions|
|lower &||Lower||upper||Lower & up|
|Tooth Pitch (in.)||0.060||0.100||0.100||0.060|
|Tooth Height (in.)||0.100||0.100||0.100||0.100|
|Tooth Length (in.)||Cont.||Cont.||0.972||Continuous|
|MD Band Spacing (in.)||—||—||—||—|
|MD Band Width (in.)||—||—||—||—|
|CD Band Width (in.)||—||—||0.0925||—|
|Tooth Tip Radius (in.)||0.005||0.005||0.005||0.005|
|Tooth End Radius (in.)||—||—||0.094||—|
|Roll Interengagement (in.)||0.090||0.105||0.060|
|MD Web Tension (lbs./linear||<0.2||0.2-.05||0.2-.05|
The resulting composite, breathable, cloth-like backsheet had the following values of performance parameters of the type desired in backsheets for disposable absorbent articles:
|Moisture Impact||2.04 g/m|
|Growth||20% after forming and spreading step 316.|
In addition to the combination of a modified nonwoven web with a polymeric film, as described earlier herein, a composite web can also be provided by joining a modified nonwoven web with a flexible web of material having some degree of elasticity. Because the modified nonwoven web is extensible and an elastomeric web is elastic, composite web structures that include both such components provide alternative materials that are elastic and that can be employed as extensible components of a disposable absorbent article.
Composite elastic materials can be used to provide backsheets and leg cuffs of disposable diapers. Additionally, they can also be used to provide localized stretchable elements of disposable diapers, such as elastic hip, waist, or leg panels, for improved fit and comfort of the articles. In order for such composite materials to function effectively in those capacities, it is preferred that the nonwoven component have as small a limiting effect as possible on the performance characteristics of the elastic component of the composite material. The elastic component is an important functional component of the composite material, significantly affecting the performance of the composite, whereas the nonwoven component is provided primarily for desired aesthetic effects, such as surface softness, cloth-like appearance, and also to provide to a composite elastic material a desirable surface coefficient of friction for the surfaces of the disposable article that come into contact with the wearer's skin and clothing.
Accordingly, the nonwoven component should have an elongation capability that is at least equal to the elongation required of the composite material during use of the article, including during application, wear, removal, and disposal. It is also desired that the nonwoven component have an elongation capability that is at least equal to the elongation to which the composite material is subjected during the manufacture of the article. More specifically, it is preferred that the elongation capability of the modified nonwoven web prior to attachment to an elastic web be in the range of from about 50% to about 200%, either in the web movement direction or in the cross-web direction.
In order to enable the composite elastic material to function most effectively, it is desirable that the force-elongation profile of the composite be as close as possible to that of the elastic component, to minimize any increase in the force-to-elongate of the composite, as compared with that of the elastic component alone. It is preferred that any increase in the force-to-elongate caused by the addition of the nonwoven component to the elastic component be less than about 40%, as compared with the elastic component alone at elongations between about 50% and about 200%. More preferably, the force increase is less than about 33%, and even more preferably the force increase is less than about 25%, again as compared with the elastic component alone at elongations between about 50% to about 200%. To ensure that the article is easy to apply and remove, and that it is also comfortable while being worn, it is preferred that the composite elastic material have a force-to-elongate of less than about 600 g/in at elongations between about 50% and about 200%. More preferably, the feorce to elongate is less than about 500 g/in, and even more preferably the force-to-elongate is less than about 400 g/in, all at elongations between about 50% and about 200%.
If the foregoing performance criteria are not met by the composite elastic material, the in-use performance of an article incorporating the material may be compromised. For example, application of a disposable diaper to a user will likely be rendered less convenient because of the greater effort necessary to stretch the composite elastic material during application. Additionally, it is also likely that poor fit of the disposable diaper may result because of the inability of the composite elastic material to elongate sufficiently to conform to the body of the wearer under usual wearing conditions and in response to body movements of the wearer. Even tearing of the nonwoven component can occur if the elongation capability of the nonwoven component is sufficiently exceeded during application or while the article is worn.
A modified nonwoven web and an elastic web can be joined to one another in surface-to-surface relationship, either at several intermittent points of surface contact or substantially continuously over at least a portion of their coextensive surfaces. The elastic component can be in either a tensioned or an untensioned condition, but preferably the modified nonwoven component is joined with the elastic component while the elastic component is in a substantially untensioned condition so that additional apparatus that would otherwise be necessary to hold the elastic component in tensioned condition during joinder is not needed. The modified nonwoven component can be joined to the elastic component after the nonwoven component has been removed from a takeup roll, or it can be joined to the elastic component immediately after having been subjected to modification of the type hereinbefore described.
The elastic component can be made from any suitable elastomeric material. Generally, any suitable elastomeric resins, or blends containing such resins, can be utilized for forming the elastomeric web. For example, the elastic component can be an elastomeric film made from block copolymers having the general formula A-B-A′, where A and A′ are each a thermoplastic polymer endblock that contains a styrenic moiety, such as a poly(vinyl arene) and where B is an elastomeric polymer midblock, such as a conjugated diene or a lower alkene polymer. Other suitable elastomeric webs, for example, can include polyurethane elastomeric materials, such is those available from B.F. Goodrich & Company of Cleveland, Ohio under the trademark ESTANE, those employing polyamide materials available from Elf Atochem of Philadelphia, Pa. under the trademark PEBAX, and polyester materials available from E.I. duPont de Nemours & Company of Wilmington, Del. under the trademark HYTREL, which are also noted hereinabove as being suitable materials for breathable films that are substantially impervious to liquids but pervious to moisture vapor.
A polyolefin can also be blended with an elastomeric resin to improve the processability of the combination. The polyolefin must be one that is extrudable, in blended form, along with the elastomeric resin. Useful blending polyolefin materials include polyethylene, polypropylene, and polybutene, as well as ethylene copolymers, polypropylene copolymers, and butene copolymers.
The elastic component can also be a pressure-sensitive elastomeric adhesive web. For example, the elastomeric material can itself be tacky or, alternatively, a compatible tackifying resin can be added to the extrudable elastomeric compositions described above, to provide an elastic component that can act as a pressure-sensitive adhesive to bond the elastic component to a modified nonwoven component. The elastic component can also be a multilayer material that can include two or more individual coherent webs or films. Additionally, the elastic component can be a multilayer material in which one or more layers contains a mixture of elastic and inelastic fibers or particles.
Other suitable elastomeric materials for use as the elastic component of a composite elastic element include “live” synthetic or natural rubber, elastomeric polyolefin metallocene catalyzed materials, heat-shrinkable elastomeric films, formed elastomeric scrim, elastomeric foams, or the like.
|Forming Roll Conditions|
|Tooth Pitch (in.)||0.060||0.060|
|Tooth Height (in.)||0.135||0.135|
|Tooth Length (in.)||Continuous||Continuous|
|Tooth Tip Radius (in.)||0.005||0.005|
|MD Web Tension||0.2-0.5|
As is apparent from
As noted previously herein, composite structures including a modified nonwoven and made in accordance with the present invention can be advantageously utilized as a component of a disposable diaper. The ensuing discussion provides additional information relating to the structure of such articles. In that regard, and as used herein in the context of disposable absorbent articles, the term “absorbent article” refers generally to devices that absorb and contain body exudates. More specifically, it refers to devices that are placed against or in proximity to the body of a wearer to absorb and contain the various exudates discharged from the body.
As used herein, the term “disposable” means absorbent articles that are not intended to be laundered or otherwise restored or reused as an absorbent article (i.e., they are intended to be discarded after a single use and, preferably, to be recycled, composted, or otherwise disposed of in an environmentally compatible manner).
As used herein, the term “disposed” means that an element of a disposable absorbent article is formed (joined and positioned) in a particular place or position as a unitary structure with other elements of the article, or as a separate element joined to another element of the article.
As used herein, the term “joined” encompasses configurations wherein an element is directly secured to another element by affixing the element directly to the other element, and also configurations wherein a first element is indirectly secured to another element by affixing the first element to an intermediate member which, in turn, is affixed to the other element.
A “unitary” absorbent article refers to absorbent articles that are formed of separate parts that are united together to form a coordinated entity so that they do not require separate manipulative parts, such as a separate holder and liner.
An embodiment of a disposable absorbent article is shown in
Other suitable backsheet materials can include breathable materials that permit moisture vapor to escape from diaper
The SELF web exhibits at least two significantly different stages of controlled resistive force to resist elongation along at least one predetermined axis when subjected to an applied elongation in a direction parallel to the predetermined axis. In that regard, the SELF web exhibits first resistive forces to the applied elongation until the elongation of the web is sufficient to cause a substantial portion of the region having the longer surface-pathlength to enter the plane of applied elongation, whereupon the SELF web exhibits second resistive forces to further resist elongation. The total resistive forces to elongation are higher than the first resistive forces to elongation provided by the first region. In that regard, SELF webs suitable for use in diaper
Adhesives that have been found to be satisfactory for joining components of diaper
Suitable formed film topsheets are described in U.S. Pat. No. 3,929,135, entitled “Absorbent Structures Having Tapered Capillaries,” which issued to Thompson on Dec. 30, 1975; U.S. Pat. No. 4,324,246, entitled “Disposable Absorbent Article Having A Stain Resistant Topsheet,” which issued to Mullane, et al. on Apr. 13, 1982; U.S. Pat. No. 4,342,314, entitled “Resilient Plastic Web Exhibiting Fiber-Like Properties,” which issued to Radel, et al. on Aug. 3, 1982; U.S. Pat. No. 4,463,045, entitled “Macroscopically Expanded Three-Dimensional Plastic Web Exhibiting Non-Glossy Visible Surface and Cloth-Like Tactile Impression,” which issued to Ahr, et al. on Jul. 31, 1984; and U.S. Pat. No. 5,006,394, entitled “Multilayer Polymeric Film,” issued to Baird on Apr. 9, 1991. Other suitable topsheets can made in accordance with U.S. Pat. Nos. 4,609,518 and 4,629,643, which issued to Curro et al. on Sep. 2, 1986, and Dec. 16, 1986, respectively. Such formed films are available from The Procter & Gamble Company, of Cincinnati, Ohio, under the designation “DRI-WEAVE,” and from Tredegar Corporation, of Terre Haute, Ind., under the designation “CLIFF-T.” The disclosures of each of those patents are incorporated herein by reference.
As an alternative, topsheet
Additionally, any portion of topsheet
The topsheet can also include or be treated with antibacterial agents, some examples of which are disclosed in International Patent Publication No. WO 95/24173, entitled “Absorbent Articles Containing Antibacterial Agents in the Topsheet For Odor Control,” which was published on Sep. 14, 1995, in the name of Theresa Johnson. Additionally, topsheet
The configuration and construction of absorbent core
Exemplary absorbent structures for use as the absorbent assemblies are described in U.S. Pat. No. 4,610,678, entitled “High-Density Absorbent Structures,” which issued to Weisman et al. on Sep. 9, 1986; U.S. Pat. No. 4,673,402, entitled “Absorbent Articles With Dual-Layered Cores,” which issued to Weisman et al. on Jun. 16, 1987; U.S. Pat. No. 4,834,735, entitled “High Density Absorbent Members Having Lower Density and Lower Basis Weight Acquisition Zones,” which issued to Alemany et al. on May 30, 1989; U.S. Pat. No. 4,888,231, entitled “Absorbent Core Having A Dusting Layer,” which issued to Angstadt on Dec. 19, 1989; U.S. Pat. No. 5,137,537, entitled “Absorbent Structure Containing Individualized, Polycarboxylic Acid Crosslinked Wood Pulp Cellulose Fibers,” which issued to Herron et al. on Aug. 11, 1992; U.S. Pat. No. 5,147,345, entitled “High Efficiency Absorbent Articles For Incontinence Management,” which issued to Young et al. on Sep. 15, 1992; U.S. Pat. No. 5,342,338, entitled “Disposable Absorbent Article For Low-Viscosity Fecal Material,” which issued to Roe on Aug. 30, 1994; U.S. Pat. No. 5,260,345, entitled “Absorbent Foam Materials For Aqueous Body Fluids and Absorbent Articles Containing Such Materials,” which issued to DesMarais et al. on Nov. 9, 1993; U.S. Pat. No. 5,387,207, entitled “Thin-Until-Wet Absorbent Foam Materials For Aqueous Body Fluids And Process For Making Same,” which issued to Dyer et al. on Feb. 7, 1995; and U.S. Pat. No. 5,625,222, entitled “Absorbent Foam Materials For Aqueous Fluids Made From high Internal Phase Emulsions Having Very High Water-To-Oil Ratios,” which issued to DesMarais et al. on Jul. 22, 1997. The disclosures of each of those patents are incorporated herein by reference.
Elastic waist feature
Examples of diapers having compartments or voids are disclosed in U.S. Pat. No. 4,968,312, entitled “Disposable Fecal Compartmenting Diaper,” which issued to Khan on Nov. 6, 1990; U.S. Pat. No. 4,990,147, entitled “Absorbent Article With Elastic Liner For Waste Material Isolation,” which issued to Freeland on Feb. 5, 1991; U.S. Pat. No. 5,062,840, entitled “Disposable Diapers,” which issued to Holt et al on Nov. 5, 1991; and U.S. Pat. No. 5,269,755, entitled “Trisection Topsheets For Disposable Absorbent Articles And Disposable Absorbent Articles Having Such Trisection Topsheets,” which issued to Freeland et al on Dec. 14, 1993.
Examples of suitable transverse barriers are described in U.S. Pat. No. 5,554,142, entitled “Absorbent Article Having Multiple Effective Height Transverse Partition,” which issued Sep. 10, 1996, in the name of Dreier et al.; International Patent Publication No. WO 94/14395, entitled “Absorbent Article Having An Upstanding Transverse Partition,” which was published Jul. 7, 1994, in the name of Freeland, et al.; and U.S. Pat. No. 5,653,703, entitled “Absorbent Article Having Angular Upstanding Transverse Partition,” which issued Aug. 5, 1997, to Roe, et al. The disclosures of each of the above-identified references relating to pockets, compartments, and transverse barriers are incorporated herein by reference.
As noted earlier herein, a nonwoven fibrous web that has been modified in accordance with the present invention can advantageously be incorporated as a functional component of a disposable absorbent article, such as a disposable diaper. For example, a modified nonwoven by itself can serve as the porous topsheet
A modified nonwoven can also be employed as a component of a composite backsheet, such as backsheet
Instead of a backsheet
Finally, a modified nonwoven can be joined with an elastomeric web to provide a composite web that can serve as an elastic component for a disposable diaper, such as elastic waist feature
Although particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. Accordingly, it is intended to encompass within the appended claims all such changes and modifications that fall within the scope of the present invention.