U.S. patent application number 10/136805 was filed with the patent office on 2003-10-30 for nonwoven materials having surface features.
This patent application is currently assigned to Kimberly-Clark Worldwide, Inc.. Invention is credited to Baratian, Stephen Avedis, Brown, Kurtis Lee, Fenwick, Christopher Dale, Haynes, Bryan David, Lambidonis, Melpo, Paul, Susan Carol, Trusock, Christian Michael.
Application Number | 20030203691 10/136805 |
Document ID | / |
Family ID | 29249665 |
Filed Date | 2003-10-30 |
United States Patent
Application |
20030203691 |
Kind Code |
A1 |
Fenwick, Christopher Dale ;
et al. |
October 30, 2003 |
Nonwoven materials having surface features
Abstract
A three-dimensional nonwoven web having a regional, bulk density
of less than 0.04 grams per cubic centimeter, a top-side base
surface that defines an x,y-plane and at least one macroscopic
surface feature extending out of the x,y-plane wherein a
macroscopic surface feature is characterized as a feature having an
apex that extends at least about 1 millimeter above the x,y-plane
of the top-side base surface is provided. The macroscopic feature
maintains a height of at least 1 millimeter above the x,y-plane of
the top-side base surface under a 1.2 kPa load (P.sub.f) and
results in contact of an object resting on the macroscopic feature
such that the percent contact area of the nonwoven web with an
article resting on the macroscopic surface feature at a 1.2 kPa
load (P.sub.f) is less than 50 percent of the bulk area of the
nonwoven web supporting the article.
Inventors: |
Fenwick, Christopher Dale;
(Alpharetta, GA) ; Haynes, Bryan David; (Cumming,
GA) ; Brown, Kurtis Lee; (Alpharetta, GA) ;
Paul, Susan Carol; (Alpharetta, GA) ; Trusock,
Christian Michael; (Cumming, GA) ; Lambidonis,
Melpo; (Cumming, GA) ; Baratian, Stephen Avedis;
(Atlanta, GA) |
Correspondence
Address: |
KIMBERLY-CLARK WORLDWIDE, INC.
401 NORTH LAKE STREET
NEENAH
WI
54956
|
Assignee: |
Kimberly-Clark Worldwide,
Inc.
|
Family ID: |
29249665 |
Appl. No.: |
10/136805 |
Filed: |
April 30, 2002 |
Current U.S.
Class: |
442/327 ;
442/205 |
Current CPC
Class: |
Y10T 442/3195 20150401;
B29L 2031/4878 20130101; D04H 3/14 20130101; B29C 59/022 20130101;
Y10T 442/60 20150401; D04H 3/16 20130101 |
Class at
Publication: |
442/327 ;
442/205 |
International
Class: |
D04H 013/00; D04H
005/00 |
Claims
We claim:
1. A three-dimensional nonwoven web having a regional, bulk density
of less than 0.04 grams per cubic centimeter and comprising a
top-side base surface that defines an x,y-plane and at least one
macroscopic surface feature extending out of the x,y-plane wherein
a macroscopic surface feature is characterized as a feature having
an apex that extends at least about 1 millimeters above the
x,y-plane of the top-side base surface and the maintains a height
of at least 1 millimeter above the x,y-plane of the top-side base
surface under a 1.2 kPa load (P.sub.f) wherein the at least one
macroscopic feature results in contact of an object resting on the
macroscopic feature such that the percent contact area of the
nonwoven web with an article resting on the macroscopic surface
feature at a 1.2 kPa load (P.sub.f) is less than 50 percent of the
bulk area of the nonwoven web supporting the article.
2. The nonwoven web of claim 1, wherein a macroscopic feature is
characterized as a feature having an apex that extends at least 1.5
millimeters above the x,y-plane.
3. The nonwoven web of claim 1, wherein a macroscopic feature is
characterized as a feature having an apex that extends at least 3
millimeters above the x,y-plane.
4. The nonwoven web of claim 1, wherein a macroscopic feature is
characterized as a feature having an apex that extends at least 5
millimeters above the x,y-plane.
5. The nonwoven web of claim 1, wherein a macroscopic feature is
characterized as a feature having an apex that extends at least
about 6 millimeters above the x,y-plane.
6. The nonwoven web of claim 1, wherein the percent contact area of
the nonwoven web with an article resting on the macroscopic surface
feature at a 1.2 kPa load (P.sub.f) is less than 40 percent of the
bulk area of the nonwoven web supporting the article.
7. The nonwoven web of claim 1, wherein the percent contact area of
the nonwoven web with an article resting on the macroscopic surface
feature at a 1.2 kPa load (P.sub.f) is less than 30 percent of the
bulk area of the nonwoven web supporting the article.
8. The nonwoven web of claim 1, wherein the percent contact area of
the nonwoven web with an article resting on the macroscopic surface
feature at a 1.2 kPa load (P.sub.f) is less than 25 percent of the
bulk area of the nonwoven web supporting the article.
9. The nonwoven web of claim 1, wherein the nonwoven web comprises
a plurality of macroscopic features and the frequency of
macroscopic features is at least 1 macroscopic surface feature per
100 square centimeters of nonwoven web in the in the x,y-plane.
10. The nonwoven web of claim 1, wherein the nonwoven web comprises
a plurality of macroscopic features and the frequency of
macroscopic features is at least 1 macroscopic surface feature per
50 square centimeters of nonwoven web in the in the x,y-plane.
11. The nonwoven web of claim 1, wherein the nonwoven web comprises
a plurality of macroscopic features and the frequency of
macroscopic features is at least 1 macroscopic surface feature per
10 square centimeters of nonwoven web in the in the x,y-plane.
12. The nonwoven web of claim 1, wherein the nonwoven web comprises
a plurality of macroscopic features and the frequency of
macroscopic features is at least 1 macroscopic surface feature per
1 square centimeter of nonwoven web in the in the x,y-plane.
13. The nonwoven web of claim 1, wherein the regional bulk density
of the nonwoven web is less than 0.03 grams per cubic
centimeter.
14. The nonwoven web of claim 1, wherein the e regional bulk
density of the nonwoven web is less than 0.02 grams per cubic
centimeter.
15. The nonwoven web of claim 9, wherein the macroscopic features
maintain a height of at least 1.5 millimeters above the x,y-plane
of the top-side base surface under a 1.2 kPa load (P.sub.f).
16. The nonwoven web of claim 9, wherein the macroscopic features
maintain a height of at least 3 millimeters above the x,y-plane of
the top-side base surface under a 1.2 kPa load (P.sub.f).
17. The nonwoven web of claim 9, wherein the macroscopic features
maintain a height of at least 6 millimeters above the x,y-plane of
the top-side base surface under a 1.2 kPa load (P.sub.f).
18. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 1 millimeter above the x,y-plane of
the top-side base surface under a 1.8 kPa load (P.sub.f).
19. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 1.5 millimeters above the x,y-plane
of the top-side base surface under a 1.8 kPa load (P.sub.f).
20. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 3 millimeters above the x,y-plane of
the top-side base surface under a 1.8 kPa load (P.sub.f).
21. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 6 millimeters above the x,y-plane of
the top-side base surface under a 1.8 kPa load (P.sub.f).
22. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 1 millimeter above the x,y-plane of
the top-side base surface under a 10 kPa load (P.sub.f).
23. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 1.5 millimeters above the x,y-plane
of the top-side base surface under a 10 kPa load (P.sub.f).
24. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 3 millimeters above the x,y-plane of
the top-side base surface under a 10 kPa load (P.sub.f).
25. The nonwoven web of claim 1, wherein the macroscopic feature
maintains a height of at least 6 millimeters above the x,y-plane of
the top-side base surface under a 10 kPa load (P.sub.f).
26. The nonwoven web of claim 9, wherein the macroscopic features
provide at least 0.08 cubic centimeters of air space between the
top surface of the nonwoven web and an article resting on the
macroscopic surface feature at a 1.2 kPa load (P.sub.f) of article
to contact area of nonwoven web per 1.0 square centimeter of
nonwoven web.
27. The nonwoven web of claim 9, wherein the macroscopic features
provide at least 0.09 cubic centimeters of air space between the
top surface of the nonwoven web and an article resting on the
macroscopic surface feature at a 1.2 kPa load (P.sub.f) of article
to contact area of nonwoven web per 1.0 square centimeter of
nonwoven web.
28. The nonwoven web of claim 9, wherein the macroscopic features
provide at least 0.10 cubic centimeters of air space between the
top surface of the nonwoven web and an article resting on the
macroscopic surface feature at a 1.2 kPa load (P.sub.f) of article
to contact area of nonwoven web per 1.0 square centimeter of
nonwoven web.
29. The nonwoven web of claim 1, wherein the nonwoven web has a
uniform composition in the x and y directions.
30. The nonwoven web of claim 1, wherein the nonwoven web comprises
a laminate.
31. The nonwoven web of claim 1, wherein the nonwoven web comprises
bicomponent fibers.
32. A three-dimensional, nonwoven web having a regional, bulk
density of less than 0.03 grams per cubic centimeter and comprising
a top-side base surface that defines an x,y-plane and a plurality
of macroscopic surface features extending out of the x,y-plane at a
frequency of at least one macroscopic feature per 100 square
centimeter of nonwoven web wherein a macroscopic surface feature is
characterized as a feature having an apex that extends at least
about 3 millimeters above the x,y-plane of the top-side base
surface and the maintains a height of at least 3 millimeters above
the x,y-plane of the top-side base surface under a 1.2 kPa load
(P.sub.f) p2 wherein the macroscopic features results in contact of
an object resting on the macroscopic feature such that the percent
contact area of the nonwoven web with an article resting on the
macroscopic surface features at a 1.2 kPa load (P.sub.f) less than
40 percent of the bulk area of the nonwoven web supporting the
article.
33. The nonwoven web of claim 32, wherein a macroscopic feature is
characterized as a feature having an apex that extends at least 5
millimeters above the x,y-plane.
34. The nonwoven web of claim 32, wherein a macroscopic feature is
characterized as a feature having an apex that extends at least
about 6 millimeters above the x,y-plane.
35. The nonwoven web of claim 32, wherein the percent contact area
of the nonwoven web with an article resting on the macroscopic
surface feature at a 1.2 kPa load (P.sub.f) is less than 30 percent
of the bulk area of the nonwoven web supporting the article.
36. The nonwoven web of claim 32, wherein the percent contact area
of the nonwoven web with an article resting on the macroscopic
surface feature at a 1.2 kPa load (P.sub.f) is less than 25 percent
of the bulk area of the nonwoven web supporting the article.
37. A three-dimensional, embossed nonwoven web having a regional,
bulk density of less than 0.03 grams per cubic centimeter and
comprising a top-side base surface that defines an x,y-plane and a
plurality of macroscopic surface features extending out of the
x,y-plane at a frequency of at least one macroscopic feature per 1
square centimeter of nonwoven web wherein a macroscopic surface
feature is characterized as a feature having an apex that extends
at least about 5 millimeters above the x,y-plane of the top-side
base surface and the maintains a height of at least 3 millimeters
above the x,y-plane of the top-side base surface under a 1.8 kPa
load (P.sub.f) wherein the macroscopic features results in contact
of an object resting on the macroscopic feature such that the
percent contact area of the nonwoven web with an article resting on
the macroscopic surface features at a 1.8 kPa load (P.sub.f) is
less than 40 percent of the bulk area of the nonwoven web
supporting the article.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to commonly assigned U.S. patent
application Ser. No. __/______ entitled "METHODS FOR MAKING
NONWOVEN MATERIALS ON A SURFACE HAVING SURFACE FEATURES AND
NONWOVEN MATERIALS HAVING SURFACE FEATURES" filed by Express Mail
Procedure EL471213680 US contemporaneously herewith and which is
hereby incorporated by reference herein.
FIELD
[0002] The present invention is directed to nonwoven materials
having surface features.
BACKGROUND
[0003] Nonwoven fabrics are useful for a wide variety of
applications, including absorbent personal care products, garments,
medical products, and cleaning products. Nonwoven personal care
products include infant care items such as diapers, child care
items such as training pants, feminine care items such as sanitary
napkins, and adult care items such as incontinence products.
Nonwoven garments include protective workwear and medical apparel
such as surgical gowns. Other nonwoven medical products include
nonwoven wound dressings and surgical dressings. Cleaning products
that contain nonwovens include towels and wipes. Still other uses
of nonwoven fabrics are well known. The foregoing list is not
considered exhaustive.
[0004] Various properties of nonwoven fabrics determine the
suitability of nonwoven fabrics for different applications.
Nonwoven fabrics may be engineered to have different combinations
of properties to suit different needs. Variable properties of
nonwoven fabrics include liquid-handling properties such as
wettability, distribution, and absorbency, strength properties such
as tensile strength and tear strength, softness properties,
durability properties such as abrasion resistance, and aesthetic
properties. The physical shape of a nonwoven fabric also affects
the functionality and aesthetic properties of the nonwoven fabric.
Nonwoven fabrics are initially made into sheets which, when laid on
a flat surface, may have a substantially planar, featureless
surface or may have an array of surface features such as apertures
or projections, or both. Nonwoven fabrics with apertures or
projections are often referred to as three-dimensional or shaped
nonwoven fabrics. The present invention relates to
three-dimensional or shaped nonwoven fabrics.
[0005] The manufacture of nonwoven fabrics is a highly developed
art. Generally, nonwoven webs and their manufacture involve forming
filaments or fibers and depositing the filaments or fibers on a
carrier in such a manner so as to cause the filaments or fibers to
overlap or entangle. Depending on the degree of web integrity
desired, the filaments or fibers of the web may then be bonded by
means such as an adhesive, the application of heat or pressure, or
both, sonic bonding techniques, or entangling by needles or water
jets, and so forth. There are several methods of producing fibers
or filaments within this general description; however, two commonly
used processes are known as spunbonding and meltblowing and the
resulting nonwoven fabrics are known as spunbond and meltblown
fabrics, respectively.
[0006] Generally described, the process for making spunbond
nonwoven fabrics includes extruding thermoplastic material through
a spinneret, quenching and drawing the extruded material into
filaments with a stream of high-velocity air to form a random web
on a forming surface. Such a method is referred to as meltspinning.
Spunbond processes are generally defined in numerous patents
including, for example, U.S. Pat. No. 3,802,817 to Matsuki et al.;
U.S. Pat. No. 4,692,618 to Dorschner, et al.; U.S. Pat. No.
4,340,563 to Appel, et al.; U.S. Pat. Nos. 3,338,992 and 3,341,394
to Kinney; U.S. Pat. No. 3,502,538 to Levy; U.S. Pat. Nos.
3,502,763 and 3,909,009 to Hartmann; U.S. Pat. No. 3,542,615 to
Dobo, et al.; and Canadian Patent No. 803,714 to Harmon.
[0007] On the other hand, meltblown nonwoven fabrics are made by
extruding a thermoplastic material through one or more dies,
blowing a high-velocity stream of air, usually heated air, past the
extrusion dies to generate an air-conveyed meltblown fiber curtain
and depositing the curtain of fibers onto a forming surface to form
a random nonwoven web. Meltblowing processes are generally
described in numerous publications including, for example, an
article titled "Superfine Thermoplastic Fibers" by Wendt in
Industrial and Engineering Chemistry, Vol. 48, No. 8, (1956), at
pp.1342-1346, which describes work done at the Naval Research
Laboratory in Washington, D.C.; Naval Research Laboratory Report
111437, dated Apr. 15, 1954; U.S. Pat. Nos. 4,041,203, 3,715,251,
3,704,198, 3,676,242 and 3,595,245; and British Specification
1,217,892.
[0008] Spunbond and meltblown nonwoven fabrics can usually be
distinguished by the diameters and the molecular orientation of the
filaments or fibers that form the fabrics. The diameter of spunbond
and meltblown filaments or fibers is the average cross-sectional
dimension. Spunbond filaments or fibers typically have average
diameters greater than 6 microns and often have average diameters
in the range of 12 to 40 microns. Meltblown fibers typically have
average diameters of less than 6 microns. However, because larger
meltblown fibers, having diameters of at least 6 microns may also
be produced, molecular orientation can be used to distinguish
spunbond and meltblown filaments and fibers of similar diameters.
For a given fiber or filament size and polymer, the molecular
orientation of a spunbond fiber or filament is typically greater
than the molecular orientation of a meltblown fiber. Relative
molecular orientation of polymeric fibers or filament can be
determined by measuring the tensile strength and birefringence of
fibers or filaments having the same diameter.
[0009] Tensile strength of fibers and filaments is a measure of the
stress required to stretch the fiber or filament until the fiber or
filament breaks. Birefringence numbers are calculated according to
the method described in the spring 1991 issue of INDA Journal of
Nonwovens Research, (Vol. 3, No. 2, p. 27). The tensile strength
and birefringence numbers of polymeric fibers and filaments vary
depending on the particular polymer and other factors; however, for
a given fiber or filament size and polymer, the tensile strength of
a spunbond fiber or filament is typically greater than the tensile
strength of a meltblown fiber and the birefringence number of a
spunbond fiber or filament is typically greater than the
birefringence number of a meltblown fiber.
[0010] A number of patents describe methods for making shaped or
three-dimensional nonwoven fabrics: for example, U.S. Pat. Nos.
5,575,874 and 5,643,653 issued to Griesbach et al.; U.S. Pat.
No.4,741,941 issued to Engelbert et al.; and U.S. Pat. Nos.
6,331,268, 6,331,345 and 6,455,319 issued to Kauschke et al.
Despite prior advances in the art, there is still a need for
improved nonwoven fabrics having surface features and methods for
forming such nonwoven fabrics.
[0011] To avoid confusion it is important to clarify the
terminology used throughout the body of the application in
describing pressures and loads. The practices used for determining
these values are detailed in the methods section. For the purposes
of describing the resiliency of surface features, the average
pressure exerted on a surface feature is denoted P.sub.f . For the
purposes of material characterization of the web and techniques
used for bulk compressometry a different pressure is reported. This
is the pressure exerted on the web or P.sub.w. P.sub.w is the
pressure that would be exerted on a flat material having 100
percent contact with the load or force.
SUMMARY
[0012] In response to the difficulties and problems encountered in
the prior art, new nonwoven materials have been discovered. In
accordance with the present invention nonwoven fabrics having one
or more macroscopic surface features are described.
[0013] The present invention provides a three-dimensional nonwoven
web having a regional, bulk density of less than 0.04 grams per
cubic centimeter wherein the nonwoven web includes a top-side base
surface that defines an x,y-plane and at least one macroscopic
surface feature extending out of the x,y-plane wherein a
macroscopic surface feature is characterized as a feature having an
apex that extends at least about 1 millimeters above the x,y-plane
of the top-side base surface and the maintains a height of at least
1 millimeter above the x,y-plane of the top-side base surface under
a 1.2 kPa load (P.sub.f) and wherein the macroscopic feature
minimizes contact of an object resting on the macroscopic feature
such that the area of contact of the nonwoven web with an article
resting on the macroscopic surface feature at a 1.2 kPa load
(P.sub.f) of article to contact area of nonwoven web is less than
50 percent of the bulk area of the nonwoven web supporting the
article.
[0014] In one embodiment, a macroscopic feature is characterized as
a feature having an apex that extends at least 1.5 millimeters
above the x,y-plane. In another embodiment, a macroscopic feature
is characterized as a feature having an apex that extends at least
3 millimeters above the x,y-plane. In yet another embodiment, a
macroscopic feature is characterized as a feature having an apex
that extends at least 5 millimeters above the x,y-plane. In still
yet another embodiment, a macroscopic feature is characterized as a
feature having an apex that extends at least about 6 millimeters
above the x,y-plane.
[0015] The area of contact of the nonwoven web with an article
resting on the macroscopic surface feature at a 1.2 kPa load
(P.sub.f) of article to contact area of nonwoven web may be less
than 40, 30 and even less than 25 percent of the bulk area of the
nonwoven web supporting the article. The nonwoven may include a
plurality of macroscopic features and the frequency of macroscopic
features is at least 1 macroscopic surface feature per 100, 50, 10
and even 1 square centimeter of nonwoven web in the x,y-plane. The
regional bulk density of the nonwoven web may be less than 0.03 and
even less than 0.02 grams per cubic centimeter.
[0016] In one particular embodiment, the macroscopic features
maintain a height of at least 1.5 millimeters above the x,y-plane
of the top-side base surface under a 1.2 kPa load (P.sub.f). In
other embodiments, the macroscopic features maintain a height of at
least 3 and even 6 millimeters above the x,y-plane of the top-side
base surface under a 1.2 kPa load (P.sub.f). In another particular
embodiment, the macroscopic feature maintains a height of at least
1 millimeter above the x,y-plane of the top-side base surface under
a 1.8 kPa load (P.sub.f). In other embodiments, the macroscopic
feature maintains a height of at least 1.5, 3 and even 6
millimeters above the x,y-plane of the top-side base surface under
a 1.8 kPa load (P.sub.f). In yet another particular embodiment, the
macroscopic feature maintains a height of at least 1 millimeter
above the x,y-plane of the top-side base surface under a 10 kPa
load. In other embodiments, the macroscopic feature maintains a
height of at least 1.5, 3 and even 6 millimeters above the
x,y-plane of the top-side base surface under a 10 kPa load.
[0017] The nonwoven webs of the present invention may include
macroscopic features that provide at least 0.08 cubic centimeters
of air space, 0.09 cubic centimeters of air space and even greater
than 0.10 cubic centimeters of air space per square centimeter
between the top surface of the nonwoven web and an article resting
on the macroscopic surface feature at a 0.3450 kPa load on the web
(P.sub.w). In several of the embodiments, the nonwoven web has a
uniform composition in the x and y directions. In several of the
embodiments, the nonwoven web is a laminate. The nonwoven web may
be made from bicomponent fibers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1A is a perspective view of a nonwoven web of the
present invention.
[0019] FIG. 1B is a cross-sectional view of the nonwoven web
illustrated in FIG. 1A.
[0020] FIG. 1C is a top-side plan view of the nonwoven web
illustrated in FIG. 1A.
[0021] FIG. 2A is a perspective view of a substantially planar
article supported on the nonwoven web of FIGS. 1A, 1B and 1C.
[0022] FIG. 2B is a cross-sectional view of a substantially planar
article supported on the nonwoven web of FIGS. 1A, 1B and 1C.
[0023] FIG. 2C is a top-side plan view of a substantially planar
article supported on the nonwoven web of FIGS. 1A, 1B and 1C.
[0024] FIG. 3A is a perspective view of an embossing plate.
[0025] FIG. 3B is a perspective view of an opposing embossing
plate.
[0026] FIG. 3C is a cross-sectional view of the embossing plates of
FIGS. 3A and 3B forming a nonwoven web of the present
invention.
[0027] FIG. 4A is a perspective view of another embossing
plate.
[0028] FIG. 4B is a perspective view of another opposing embossing
plate.
[0029] FIG. 5A is a perspective view of another nonwoven web of the
present invention.
[0030] FIG. 5B is a cross-sectional view of the nonwoven web
illustrated in FIG. 5A.
[0031] FIG. 5C is a top-side plan view of the nonwoven web
illustrated in FIG. 5A.
[0032] FIG. 6 is a cutaway view of an absorbent article
incorporating a nonwoven fabric of the invention.
[0033] FIG. 7 is a partial cross-sectional view of the absorbent
article of FIG. 6.
[0034] FIG. 8 is a perspective view of yet another nonwoven web of
the present invention.
DEFINITIONS
[0035] As used herein the following terms have the specified
meanings, unless the context demands a different meaning, or a
different meaning is expressed; also, the singular generally
includes the plural, and the plural generally includes the singular
unless otherwise indicated.
[0036] Words of degree, such as "about", "substantially", and the
like are used herein in the sense of "at, or nearly at, when given
the manufacturing and material tolerances inherent in the stated
circumstances" and are used to prevent the unscrupulous infringer
from unfairly taking advantage of the invention disclosure where
exact or absolute FIGS. are stated as an aid to understanding the
invention.
[0037] As used herein, the term "absorbent product" or "personal
care absorbent product" means diapers, training pants, swim wear,
absorbent underpants, adult incontinence products, sanitary wipes,
wipes, feminine hygiene products, wound dressings, nursing pads,
time release patches, bandages, mortuary products, veterinary
products, hygiene and so forth.
[0038] As used herein, the term "airlaid web" refers to nonwoven
webs made by "airlaying". Airlaying is a well-known process by
which a fibrous nonwoven layer can be formed. In the airlaying
process, bundles of small fibers having typical lengths ranging
from about 3 to about 52 millimeters (mm) are separated and
entrained in an air supply and then deposited onto a forming
screen, usually with the assistance of a vacuum supply. The
randomly deposited fibers then are bonded to one another using, for
example, hot air or a spray adhesive. Airlaying is taught in, for
example, U.S. Pat. No. 4,640,810 to Laursen et al.
[0039] As used herein, the term "apex" refers to the highest or
furthest portion of a feature and is meant to include points as
well as planes and other surfaces that are not sharp ends.
[0040] As used herein, the term "bonded carded web" refers to webs
that are made from staple fibers which are sent through a combing
or carding unit, which separates or breaks apart and aligns the
staple fibers in the machine direction to form a generally machine
direction-oriented fibrous nonwoven web. This material may be
bonded together by methods that include point bonding, through air
bonding, ultrasonic bonding, adhesive bonding, etc.
[0041] As used herein, the terms "comprises", "comprising" and
other derivatives from the root term "comprise" are intended to be
open-ended terms that specify the presence of any stated features,
elements, integers, steps, or components, but do not preclude the
presence or addition of one or more other features, elements,
integers, steps, components, or groups thereof.
[0042] As used herein, the term "fabric" refers to all of the
woven, knitted and nonwoven fibrous webs.
[0043] As used herein, the term "hydrophilic" describes fibers,
materials or the surfaces of fibers materials that are wetted by
the aqueous liquids in contact with the fibers or other materials.
The degree of wetting of the materials can, in turn, be described
in terms of the contact angles and the surface tensions of the
liquids and materials involved. Equipment and techniques suitable
for measuring the wettability of particular fiber materials can be
provided by a Cahn SFA-222 Surface Force Analyzer System, or a
substantially equivalent system. When measured with this system,
fibers having contact angles less than 90.degree. are designated
"wettable" or hydrophilic, while fibers having contact angles equal
to or greater than to 90.degree. are designated "nonwettable" or
hydrophobic.
[0044] As used herein, the term "macroscopic surface features"
describes three-dimensional features that extend from the surface
and are large enough to be perceived or examined with the unaided
eye, desirably such features have at least one dimension that is
greater than {fraction (3/32)} of an inch (.about.1 mm), more
desirably such features have at least one dimension that is greater
than one sixteenth of an inch (.about.1.5 mm), still more desirably
such features have at least one dimension greater than one eighth
of an inch (.about.3 mm) and even more desirably such features have
at least one dimension greater than one quarter of an inch
(.about.6 mm).
[0045] As used herein the term "meltblown fibers" means fibers
formed by extruding a molten thermoplastic material through a
plurality of fine, usually circular, die capillaries as molten
threads or filaments into converging high velocity, usually hot,
gas (e.g. air) streams which attenuate the filaments of molten
thermoplastic material to reduce their diameter, which may be to
microfiber diameter. Thereafter, the meltblown fibers are carried
by the high velocity gas stream and are deposited on a forming
surface to form a web of randomly dispersed meltblown fibers. Such
a process is disclosed, for example, in U.S. Pat. No. 3,849,241 to
Butin et al. Meltblown fibers are microfibers, which may be
continuous or discontinuous, are generally smaller than 10 microns
in average diameter, and are generally tacky when deposited onto a
forming surface.
[0046] As used herein "multilayer laminate" means a laminate
including two or more layers of material laminated into a finished
structure. For example, one or more of the layers may be a spunbond
layer and/or some of the layers may be a meltblown layer. One
specific example of a multilayer laminate is a
spunbond/meltblown/spunbond (SMS) laminate. Other multilayer
laminates are disclosed in U.S. Pat. No. 4,041,203 to Brock et al.,
U.S. Pat. No. 5,169,706 to Collier, et al, U.S. Pat. No. 5,145,727
to Polls et al., U.S. Pat. No. 5,178,931 to Perkins et al. and U.S.
Pat. No. 5,188,885 to Timmons et al. A multilayer laminate may be
made by sequentially depositing onto a moving forming belt first a
spunbond fabric layer, then a meltblown fabric layer and last
another spunbond layer and then bonding the laminate in a manner
described below. Alternatively, the fabric layers may be made
individually, collected in rolls, and combined in a separate
bonding step. Such fabrics usually have a basis weight of from
about 0.1 to 12 ounces per square yard (osy) [3 to 400 grams per
square meter (gsm)], or more particularly from about 0.75 osy to
about 3 osy (25-102 grams per square meter). Multi-layer laminates
may also have various numbers of meltblown layers or multiple
spunbond layers in many different configurations and may include
other materials like films (F) or coform materials, e.g. SMMS, SM,
SFS, and so forth.
[0047] As used herein the terms "nonwoven" and "nonwoven fabric or
web" mean a web having a structure of individual fibers, filaments
or threads which are interlaid, but not in an identifiable manner
as in a knitted fabric. Nonwoven fabrics or webs have been formed
from many processes such as for example, meltblowing processes,
spunbonding processes, and bonded carded web processes. The basis
weight of nonwoven fabrics is usually expressed in ounces of
material per square yard (osy) or grams per square meter (gsm) and
the fiber diameters useful are usually expressed in microns. (Note
that to convert from osy to gsm, multiply osy by 33.91).
[0048] As used herein, the term "solid" does not completely exclude
the presence of voids or cavities in the interior of the
projections. On the contrary, as will be apparent to those skilled
in the art, the forming the projections may well leave voids or
cavities in the projections due to variabilities in processing. The
term "solid" as used herein, therefore, means that the interior of
a given projection is not substantially free from fibers or
filaments or other solid when compared with the base material.
[0049] As used herein the term "spunbonded webs" refers to webs
comprising small diameter fibers which are formed by extruding
molten thermoplastic material as filaments from a plurality of
fine, usually circular capillaries of a spinneret with the diameter
of the extruded filaments then being rapidly reduced as by, for
example, in U.S. Pat. No. 4,340,563 to Appel et al., and U.S. Pat.
No. 3,692,618 to Dorschner et al., U.S. Pat. No. 3,802,817 to
Matsuki et al., U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney,
U.S. Pat. No.3,502,763 to Hartman, and U.S. Pat. No. 3,542,615 to
Dobo et al. Spunbond fibers are generally not tacky when they are
deposited onto a forming surface. Spunbond fibers are generally
continuous and have average diameters (from a sample of at least
10) larger than 7 microns, more often, between about 10 and 20
microns.
[0050] These terms may be defined with additional language in the
remaining portions of the specification.
DETAILED DESCRIPTION
[0051] As discussed above, the present invention provides
three-dimensional nonwoven fabrics having one or more macroscopic
surface features. It is desirable that the surface features are
macroscopic in size and provide separation between the majority of
the nonwoven fabric surface and a body part that is in contact with
the nonwoven fabric. Such a nonwoven fabric is particularly useful
as a body side liner in a personal care article, such as a diaper,
pantiliner and so forth. Nonwoven fabrics of the present invention
may further indude apertures and non-macroscopic projections as
well as the macroscopic features. Nonwoven fabrics of the present
invention are also useful for making garments, medical products,
cleaning products, packaging materials, construction materials such
as sound proofing and insulation, and so forth.
[0052] Exemplary nonwoven webs of the present invention are
illustrated in FIGS. 1A, 1B and 1C; FIGS. 5A, 5B and 5C; and FIG.
8. The present invention will be described with reference to the
exemplary nonwoven web illustrated in FIGS. 1A, 1B and 1C. The
nonwoven web is a three-dimensional nonwoven web 100 that includes
a top-side base surface 104 that defines an x,y-plane and at least
one macroscopic surface feature 120 extending out of the x,y-plane
wherein a macroscopic surface feature 120 is characterized as a
feature having an apex 106 that extends at least about 1 millimeter
above the x,y-plane of the top-side base surface 106. The nonwoven
web illustrated in FIGS. 1A, 1B and 1C and described in greater
detail in Example 1 includes macroscopic features having apexes 106
that extend at least about 2 millimeters above the x,y-plane of the
top-side base surface 106. The nonwoven web illustrated in FIGS.
5A, 5B and 5C and described in greater detail in Example 5 includes
macroscopic features having apexes 106 that extend at least about 3
millimeters above the x,y-plane of the top-side base surface 106.
In certain embodiments, the macroscopic features have an apex that
extends at least about 1, 1.5, 3, 5 or even about 6 millimeters
above the x,y-plane. It is desirable that the macroscopic features
120 have increased height to provide increased separation.
Increased height of the macroscopic features increases the bulk
thickness T of the web and thus decreases the bulk density of the
nonwoven web. For example, the regional bulk density of a nonwoven
web of the present invention may be less than 0.04 grams per cubic
centimeter, less than 0.03 grams per cubic centimeter or even less
than 0.02 grams per cubic centimeter.
[0053] It is also desirable that the macroscopic features 120
maintain a height of at least 1 millimeter above the x,y-plane of
the top-side base surface 104 under a particular load, for example
under a 1.2 kPa load (P.sub.f), to minimize contact when pressure
is applied to the nonwoven web 100. In certain embodiments, the
macroscopic features maintain a height h of at least about 1, 1.5,
3, 5 or even 6 millimeters above the x,y-plane of the top-side base
surface 104 under load. A substantially planar article resting on
the nonwoven web of FIGS. 1A, 1B and 1C is illustrated in FIGS. 2A,
2B and 2C to demonstrate some of the features of the nonwoven webs
of the present invention. The contact area of an object P with a
nonwoven sheet 100 is the sum of the area(s) 106 of the nonwoven
sheet that directly contact the object P resting on the nonwoven
sheet, more particularly the macroscopic features 120. For example,
the contact area of an object P supported by surface features 120
of a nonwoven 100 is the sum of the areas of all of the features
and any other parts of the nonwoven web, if any, that directly
contact the object P resting on the features 120. In FIG. 2A, the
contact area of object P with the nonwoven 100 is the sum of the
cross-hatched areas shown in FIGS. 2A and 2C. The percent contact
area that an object P has with a nonwoven web supporting P with
features 120, is measured by dividing the contact area described
above by the flat contiguous area that connects all of the points
of the sheet that directly contact the article. For example, if an
object is supported by sixteen macroscopic features 100, then the
area of the nonwoven web that includes the features supporting the
object P is the contiguous "bulk area" (L.sub.p.times.W.sub.p)
measured in a plane parallel to the nonwoven base plane that
connects all of the sixteen features or the parts of the sixteen
features that support the object. Therefore the percent contact
area would be the contact area divided by the bulk area
(L.sub.p.times.W.sub.p). In FIG. 2C, the pressure that an object P
supported by the nonwoven transmits to the sheet P.sub.w is
measured by dividing the weight of the supported object P by the
flat contiguous area (L.sub.p.times.W.sub.p) beneath the object.
The average pressure observed by the surface feature P.sub.f is
determined by correcting for the actual area in contact with the
load. The average pressure observed by the surface feature P.sub.f
can be determined by dividing P.sub.w by the percent contact
area.
[0054] Desirably, the macroscopic feature(s) 120 minimize contact
of an object resting on the feature(s) such that the area of
contact of the nonwoven web with an article resting on the
macroscopic surface feature at given load is less than 50 percent
of the bulk area of the nonwoven web (L.sub.p.times.W.sub.p)
supporting the article. More desirably, the area of contact of the
nonwoven web with an article resting on the macroscopic surface
feature at a given load of article to contact area of nonwoven web
may be less than 40, 30 and even less than 25 percent of the bulk
area of the nonwoven web supporting the article. Thus, it is
desirable that the nonwoven web and the macroscopic features of the
nonwoven web do not compress completely under a given load so that
the features minimize contact area and provide separation under a
given load. It is also desirable that the features are resilient
and return to some measurable height h, desirably greater than 1
mm, after a 3.45 kPa load is applied to the web so that the
features provide separation after a 3.45 kPa is applied to the web
and is then removed.
[0055] The nonwoven may include a plurality of macroscopic features
to provide separation over a larger area or to provide increased
support. The frequency of macroscopic features may vary greatly.
For example, it is envisioned that nonwoven webs of the present
invention may include as few as 1 macroscopic surface feature per
1, 10, 50 or even 100 square centimeters of nonwoven web in the in
the x,y-plane. It is desirable to decrease the number of
macroscopic features per unit area of web to decrease contact area.
The frequency of the macroscopic features in Examples 1-3 below was
about 2 features per square centimeter and about 1 feature per
square centimeter in Examples 4 and 5. The frequency of the
macroscopic feature illustrated in FIG. 8 may be one feature per
500 square centimeters.
[0056] As illustrated in FIG. 8, it is not necessary to provide
macroscopic features 120 over the entire surface 104 of the web
100. For example, one or more macroscopic feature may be provided
in a particular location, for example the target zone of a diaper
liner, to provide separation in that location as illustrated in
FIG. 8. FIG. 8 illustrates a nonwoven web 100 that includes only
one macroscopic surface feature 120 measuring about 10 centimeters
by 10 centimeters along the exterior widths and an interior opening
dimension of about 9 centimeters by 9 centimeters. The macroscopic
feature 120 has a height of about 4 millimeters. The single
macroscopic features 120 desirably should be located in the target
zone of a diaper liner to provide separation between a baby's
bottom and the diaper liner surface and any absorbent material
located beneath the liner in the target zone.
[0057] In one particular embodiment, the macroscopic features
maintain a height of at least 1 millimeter above the x,y-plane of
the top-side base surface under a 1.2 kPa load (P.sub.f). In
another embodiment, the macroscopic features maintain a height of
at least 1.5 millimeters above the x,y-plane of the top-side base
surface under a 1.2 kPa load (P.sub.f). In yet other embodiments,
the macroscopic features maintain a height of at least 3, 5 and
even 6 millimeters above the x,y-plane of the top-side base surface
under a 1.2 kPa load (P.sub.f). In another particular embodiment,
the macroscopic feature maintains a height of at least 1 millimeter
above the x,y-plane of the top-side base surface under a 1.8 kPa
load (P.sub.f). In other embodiments, the macroscopic feature
maintains a height of at least 1.5, 3 and even 6 millimeters above
the x,y-plane of the top-side base surface under a 1.8 kPa load
(P.sub.f). In yet another particular embodiment, the macroscopic
feature maintains a height of at least 1 millimeter above the
x,y-plane of the top-side base surface under a 10 kPa load. In
other embodiments, the macroscopic feature maintains a height of at
least 1.5, 3 and even 6 millimeters above the x,y-plane of the
top-side base surface under a 10 kPa load. The nonwoven webs of the
present invention may include macroscopic features that provide at
least 0.08, 0.09 and even greater than 0.10 cubic centimeters per
square centimeter of air space between the top surface of the
nonwoven web and an article resting on the macroscopic surface
feature at a 0.3450 kPa load on the web (P.sub.w).
[0058] In the exemplary embodiments, the nonwoven web is
illustrated as a single layer web that has a uniform composition in
the x, y and z directions. However, nonwoven webs of the present
invention may be laminates having a uniform composition in the in
both the x and the y directions. In the exemplary embodiments, the
nonwoven webs of the present invention are also bicomponent
spunbond nonwoven webs. However, nonwoven webs of the present
invention can be made by methods other than spunbond methods and
may include single component and/or multicomponent fibers,
filaments and layers.
[0059] Spunbond nonwoven webs are formed by depositing melt spun,
continuous multicomponent polymeric fibers onto a forming surface.
Bicomponent fibers and melt spinning are known and are described in
U.S. Pat. Nos. 5,575,874 and 5,643,653 issued to Griesbach et al.
which are herein incorporated by reference in their entirety.
Multicomponent meltspun nonwoven fabrics and methods of making
multicomponent meltspun nonwoven fabrics are also known and are
described in U.S. Pat. No. 5,382,400 issued to Pike et al. which is
also herein incorporated by reference in its entirety. Methods for
extruding multicomponent polymeric filaments are also known.
Suitable materials for preparing the bicomponent filaments of the
nonwoven fabrics of the present invention include PD-3155
polypropylene available from Exxon Mobil of Houston, Tex.; a linear
low density polyethylene (LLDPE) available under the designation
ASPUN 6811A, 2553 LLDPE and 61800 polyethylene available from Dow
Chemical Company of Midland, Mich.; and 25355 and 12350 HDPEs
available from Dow Chemical Company. When a polypropylene is
component A and a polyethylene is component B, the bicomponent
filaments may comprise from about 20 to about 80 percent by weight
of a polypropylene and from about 80 to about 20 percent
polyethylene. More desirably, the filaments may comprise from about
40 to about 60 percent by weight polypropylene and from about 60 to
about 40 percent by weight polyethylene.
[0060] It is desirable that the filaments of the nonwoven web are
crimped to provide a lofty nonwoven. Although the illustrated
method of carrying out the present invention includes
multicomponent filaments that are crimped, the present invention
encompasses uncrimped fibers as well as fibers that are crimped by
other methods, for example mechanically crimping fibers. Crimped
fibers and methods of crimping fibers are known in the art. The
present invention also contemplates use of nonwoven webs made by
other methods for example, bonded carded webs, meltblown webs and
webs made from uncrimped filaments and/or single component
filaments. When the spunbond filaments are crimped, the fabric of
the present invention advantageously results in a relatively high
loft material that is also relatively resilient. The crimp of the
filaments creates an open web structure with substantial void
portions between filaments and the filaments are bonded at points
of contact of the filaments. Again, although the nonwoven fabric
described above is made with spunbond bicomponent filaments, it
should be understood that nonwoven fabrics of the present invention
may be made with single component spunbond filaments, meltblown
filaments, bonded carded webs, air laid webs and so forth. For
example, single component spunbond filaments can be made in the
same manner as described in the Examples except that the spinneret
will be adapted to make single component filaments. See, for
example, the patents previously identified with respect to spunbond
processes. Furthermore, the fibers may be bonded by adding an
adhesive polymeric component in another manner.
[0061] A spunbond/meltblown/spunbond (SMS) laminate nonwoven fabric
can be made to include macroscopic surface features. Meltblown
processes of making nonwoven fabrics and SMS nonwoven fabrics are
known. Suitable meltblowing techniques and SMS fabrics are
disclosed in U.S. Pat. No. 4,041,203, the disclosure of which is
incorporated herein by reference. U.S. Pat. No. 4,041,203
references the following publications on meltblowing techniques
which are also incorporated herein by reference: an article
entitled "Superfine Thermoplastic Fibers" appearing in Industrial
Engineering Chemistry, Volume 48, Number 8, ppgs. 1342-1346 which
describes work done at the U.S. Naval Research Laboratories in
Washington, D.C.; Naval Research Laboratory Report 111437, dated
Apr. 15, 1954; U.S. Pat. Nos. 3,715,251; 3,704,198; 3,676,242; and
3,595,245; and British Specification No.1,217,892.
[0062] Spunbond meltblown integrated composite (SMIC) materials are
described and illustrated in the previously mentioned U.S. Pat.
Nos. 5,575,874 and 5,643,653 issued to Griesbach et al. Generally,
an SMIC material can be produced by meltblowing material on each
side of a spunbond filament curtain. Meltblowing dies can be
positioned on each side of the spunbond filament curtain in a
symmetric fashion to produce a SMIC fabric. The process is
described in more detail in U.S. Pat. Nos. 5,575,874 and 5,643,653
issued to Griesbach et al. which are incorporated by reference
herein. The SMIC fabric that is formed can be positioned on a
surface that includes topographical features and bonded with hot
air to provide a SMIC fabric that includes surface features.
[0063] When used to make liquid absorbent articles, a nonwoven
fabric of the present invention may be treated with conventional
surface treatments or contain conventional polymer additives to
enhance the wettability of the fabric. For example, the nonwoven
fabric may be treated with polyalkylene-oxide modified siloxanes
and silanes such as polyalkylene-oxide modified
polydimethyl-siloxane as disclosed in U.S. Pat. No. 5,057,361. Such
a surface treatment enhances the wettability of the fabric. The
nonwoven web may be treated before it is incorporated into a
product.
[0064] Nonwoven fabrics of the present invention may include
nonwoven fabrics having zones of different liquid handling
properties. More specifically, a nonwoven fabric of the present
invention may include a fabric that directs flow along all three
dimensions of the fabric: along the length of the fabric coplanar
with the land areas, along the width of the fabric coplanar with
the land areas, and through the thickness or depth of the fabric.
These zones of different liquid handling ability are created by
areas of topographical surface definition. These topographical
regions can vary in basis weight, density and/or filament
orientation. In addition, the topographical features can have
phobicity differences, which further enhance fluid handling.
[0065] As previously stated, nonwoven fabrics of the present
invention can be used as separation layers or body side liner
materials and may include materials having one large projection or
a relatively small number of spaced projections. The present
invention includes a nonwoven structure having macroscopic surface
features that can be used to separate one surface from another
surface, for example, a baby's bottom from an absorbent layer of a
diaper. In several desirable embodiments, the structure has
physical, aesthetic, and functional attributes that are
particularly desirable for use as a body-side liner; a surge
material or a liner/surge combination in disposable absorbent
products such as: diapers; training pants; incontinent pads;
feminine hygiene products such as feminine pads, sanitary napkins,
and pantiliners; and so forth.
[0066] The discussion that follows is primarily directed to the use
of the invention as a unique moisture-pervious top-sheet structure
100 embodied in a disposable diaper 400 as illustrate in FIGS. 7
and 8. While this is contemplated as being one desirable use, it
should be understood that the present invention also has utility in
a wide variety of absorptive devices, both disposable and reusable,
such as sanitary napkins, catamenial tampons, incontinent pads, and
so forth and in non-absorptive devices, such as industrial
materials, sound proofing, insulation, packaging and so forth. The
detailed description of the top-sheet structure 700 and its use in
a disposable diaper 400 will allow those skilled in the art to
readily adapt the invention to other devices.
[0067] As previously stated, it is desirable that the surface
features of a web of the present invention are resistant to
compression so that the web can be used as a body-side liner in a
diaper or other absorbent product to separate the absorbent portion
of the absorbent product from the wearer's skin. A view of a
disposable absorbent product, for example a diaper 400, is provided
in FIG. 6. Various layers have been cut away to more clearly show
the structural details of this particular embodiment. A novel
topsheet or body-side liner of the present invention is shown at
700. The other two major components of the disposable diaper 400
are an absorbent element or pad 410 and a backsheet 430. The
drawing of diaper 400 in FIG. 6 is a simplified representation of a
disposable diaper. A more detailed description of a disposable
diaper is contained in U.S. Pat. No. 5,827,259 issued to Laux et
al. and is hereby incorporated herein by reference.
[0068] FIG. 7 illustrates a cross-sectional view taken through line
7-7 of FIG. 6. The surface features 720 separate a wearer's skin
450 from absorbent material 410 located beneath the liner 700. The
liner 420 rests on the absorbent material 410 at base areas 702.
Desirably, the contact area of the surface features is less than
the contact area of the base areas. Specifically, it is desirable
that the nonwoven web 700 is oriented with the macroscopic surface
features 720 that provide the least contact area under load are
pointing toward the wearer 450. It is also desirable that the
contact area of a wearer with the liner is less than 50 percent of
the surface area or footprint of wearer on the liner, more
desirably the contact area is less than 40 percent, 30 percent and
even more desirably the contact area is less than 25 percent. It is
believed that reduction in contact between the wearer's skin and
wet or damp portions of a diaper improves the skin health of the
wearer. It is also believed that separation will improve fluid
handling of an absorbent article.
[0069] It is not necessary that the surface features are completely
resistant to compression.
[0070] The surface features may compress when a compressive force
is applied to the topography. For example, when a baby sits down a
majority of the baby's weight is transmitted to the surface
features and the liner surface and the features may substantially
compress providing little separation between the liner surface and
the wearer's skin. However, it is desirable that the topography is
not completely compressed during normal use and that some degree of
separation is provided by the topography. It is also desirable that
the surface features are resilient and are not permanently deformed
by forces likely to be transmitted to the surface features during
normal use. Specifically, it is desirable that deformation is
within the elastic limits of the surface features and the
accompanying structure. Thus, a wearer's skin is separated from a
substantial portion of the liner surface by the surface features
during use. The surface features should provide some degree of
separation when a baby is at rest, crawling or walking and
desirably even when a majority of the baby's weight is transmitted
to the surface features or to the liner.
[0071] Although the nonwoven fabric webs of the exemplary
embodiments were made by embossing spunbond webs, nonwoven webs of
the present invention can be made through the use of other methods.
Those of skill in the art will appreciate that a nonwoven web of
the present invention can be made via other methods of making webs
other than spunbond methods and by methods other than embossing.
For example, a nonwoven web having surface macroscopic surface
features can be made by the methods described in U.S. patent
application Ser. No.__/______, entitled "METHODS FOR MAKING
NONWOVEN MATERIALS ON A SURFACE HAVING SURFACE FEATURES AND
[0072] NONWOVEN MATERIALS HAVING SURFACE FEATURES" filed by Express
Mail Procedure EL471213680 US contemporaneously herewith and which
is hereby incorporated by reference herein. Again, other processes
of making nonwoven webs can be adapted to make webs that include
surface features within the present invention. For example the
nonwoven web may be a bonded-carded web (BCW), a coform web, an
airlaid web, a spunbond/meltblown/spunbond (SMS) web and so forth.
Additionally, the webs can be formed from or include a variety of
materials, cellulose, pulp fibers, bicomponent fibers, and so
forth. Other modifications and treatments known to those of skill
in the art may be used with the present invention.
[0073] Nonwoven fabrics having stabilized three-dimensional,
macroscopic topographical features can be produced by thermoforming
flat non-woven base sheets. The nonwoven base sheet may be a
bonded-carded web (BCW), a coform web, an airlaid web, a
spunbond/meltblown/spunbond (SMS) web and so forth. Desirably, the
webs are thermoformed to have surface features over less than 50
percent of the area of the web, more desirably, less than 40
percent, still more desirably less than 30 percent and most
desirably less than 25 percent. It is also desirable that the
material and basis weight of the web and the pattern that is
thermoformed are selected so that the features do not completely
compress and provide separation at a pressure on the feature
(P.sub.f) of 1.2 kPa, more desirably do not completely compress and
provide separation at 1.8 kPa and even at 10 kPa. It is also
desirable that the surface features that are thermoformed are at
least 1 mm in height to provide increase separation and air
circulation between the majority of the nonwoven material surface
and a body that is in contact with the nonwoven material surface.
It may be further desirable to provide surface features that are at
least 1.5 mm, 3 mm, 5 mm, and even 6 mm in height.
[0074] A nonwoven base sheet may be thermoformed to include
macroscopic features on a heated surface, for example mating plates
having surface features on a heated press, having macroscopic
features. Heated presses are well known in the art and are readily
available. The press should be set at a temperature high enough
that to allow the nonwoven web to be permanently deformed but not
so high so as to destroy the desirable properties of the nonwoven,
for example breathability. Forming plates may have any of a variety
of features to impart surface features to the nonwoven. A first
pattern of surface features is illustrated in FIGS. 3A, 3B, and 3C
and a second pattern of surface features is illustrated in FIGS. 4A
and 4B. Each set of plates includes a first plate and a second
plate having an array of surface features, for example squares or
triangles, respectively. A variety of other patterns are possible,
for example hexagons and diamonds, provided that one or more of the
features are macroscopic. Two basic plate designs may be used for
forming these plates, standard male and female plates or
interdigitated plates. In the examples described herein
interdigitating plates were used to provide repeating patterns of
squares and triangles. The nonwoven base sheet is placed between
the plates and heat and pressure are applied to thermoform the
nonwoven base sheet. Three-dimensional nonwoven sheets having
stabilized macroscopic topography were produced in the Examples.
Although the illustrated nonwoven fabrics include surface features
that are uniformly distributed in both the x-direction and the
y-direction, nonwoven fabrics of the invention may include features
that are uniformly distributed in only one direction. Furthermore,
nonwoven fabrics of the invention may include features that are not
uniformly provided or distributed on the fabric surface and can be
provided and distributed in any pattern.
[0075] Nonwoven webs of the present invention that include
macroscopic surface features may be treated with optional
treatments and/or additives to modify one or more properties of the
web. For example, non-raised areas of the webs may be treated with
a hydrophilic treatment to increase fluid intake. The resulting
non-treated raised areas, i.e. the surface features, will be more
hydrophobic relative to the treated non-raised areas. Thus, this
web provides drier, raised surface contact areas and improving
overall skin dryness. The surface features can run the entire
length or width of a structure. The surface features can vary in
rigidity to increase or decrease the weight-bearing capacity of the
features and the nonwoven web.
[0076] In order to provide a better understanding of some features
of nonwoven webs of the present invention, and not by way of
limitation, the following examples and data are provided.
COMPARATIVE EXAMPLE A
[0077] A diaper liner material was used as a comparative example,
Comparative Example A. Comparative Example A was a 0.5 osy nonwoven
synthetic fabric web formed 98 percent by weight of 3155
polypropylene from Exxon of Houston, Tex. and 2 percent by weight
of titanium dioxide. The 0.5 osy nonwoven synthetic fabric web was
formed by a spunbonded process. Fibers having a round cross section
were used to form the web and had an average diameter of the
approximately 22 microns (3 dpf). The web was formed by randomly
laying continuous filaments and then thermal point bonding the
randomly laid filaments. The thermal point bonding of the web was
accomplished with a pattern having a bond area of 14-21 percent and
a pin density of 460 pins/in.sup.2. The pin geometry was a diamond
geometry. Additional details of the liner material can be found in
U.S. Pat. No. 6,152,904 hereby incorporated by reference
herein.
EXAMPLE 1
[0078] A nonwoven synthetic fabric web having macroscopic surface
features was prepared by first forming an underbonded, bicomponent
spunbond web and then embossing macroscopic features into the
underbonded web. The macroscopic surface features were embossed
into the web using heat and pressure applied by heated plates, with
one of the plates having at least one macroscopic feature, to
impart permanently deformed macroscopic projections into the
web.
[0079] The underbonded, bicomponent spunbond nonwoven fabric web
was formed from continuous bicomponent filaments. Continuous
bicomponent filaments were made from approximately equal amounts of
two polymer components in a side-by-side configuration. The
composition of the first polymer component was 98 percent by weight
of 3155 polypropylene from Exxon of Houston, Tex. and 2 percent by
weight of titanium dioxide. The composition of second component was
100 percent by weight of 61800 polyethylene from Dow Chemical
Company of Midland, Mich. The spin hole geometry of the spin pack
was 0.6 mm diameter with a length to diameter (L/D) ratio of 4:1
and the spinneret had 50 holes per inch (19.685 holes per cm) in
the cross direction. The melt temperature in the spin pack was
410.degree. F. (210 C) and the throughput was 0.6 grams/hole/minute
(ghm). The forming height was 12 inches (30.5 cm). The quench air
flow rate of the air quencher was 32 standard cubic feet per minute
(scfm) and the temperature was 50.degree. F. aspirator temperature
was ambient, approximately 75.degree. F. (23.9.degree. C.), and the
aspirator pressure was 3.5 pounds per square inch (psi) (24.31
kPa). An under wire vacuum at 7 inches water (17,440
dynes/cm.sup.2) was used to collect the filaments onto a forming
wire. A hot air knife (HAK) at 270.degree. F. (132.2.degree. C.)
inlet air with an exit air temperature of 180.degree. F.
(82.2.degree. C.), pressure was 0.8 psi (5.52 kPa) and the height
of the HAK above the wire was 1.5 inches (3.8 cm) was used to help
integrate the filaments into an underbonded web. The unbonded
nonwoven was then directed to a Through Air Bonder (TAB). The TAB
was set at an air temperature of approximately 270.degree. F.
(132.2.degree. C.) and 0.5 psi (34,470 dynes/cm.sup.2) of air
pressure and exhaust to form the fibers into an underbonded but
integrated web. The line speed was adjusted to approximately 290
ft/min. (88.5 m/min.) to produce a 0.5 ounces per yard (osy) [17
grams per square meter (gsm)] nonwoven material.
[0080] This underbonded web was then thermoformed into a
three-dimensional nonwoven sheet having stabilized macroscopic
topography by embossing a three-dimensional "squares" pattern into
the web using heat and pressure applied by the heated
interdigitating plates 300 and 350 illustrated in FIGS. 3A and 3B.
Each interdigitating plate included a pattern of projections that
intemeshed with a similar pattern of projections on the opposing
plate. The first plate 300 included a checkerboard pattern of
square projections as shown in FIG. 3A. Each projection 310 on the
first plate was approximately 3 millimeters in height and measured
approximately 5 millimeters by 5 millimeters at the base and
terminated in a square distal top surface 320 that measured
slightly greater than 3 millimeters by 3 millimeters (approximately
3.5 mm.times.3.5 mm). The projections were spaced apart
approximately 9.5 millimeters from center to center in both x and y
directions. The second plate 350 illustrated in FIG. 3B included a
similar pattern of alternating square projections 310 of
approximately 4 millimeters in height, with each projection 310
measuring approximately 4 millimeters by 4 millimeters at the base
and terminating in square distal top surface 320 that measured
slightly less than 3 millimeters by 3 millimeters (approximately
2.9 mm.times.2.9 mm).
[0081] The patterned plates were heated to a temperature of about
275.degree. F. (135.degree. C.) and the underbonded web was placed
on one of the heated plated. The opposing heated plate was then
placed on over the web so that the projections on the second plate
intermeshed with the projections on the first plate as illustrated
in FIG. 3C. Embossing pressure of approximately 115 psi (793 kPa)
was then applied to the plates for approximately 35 seconds. After
sufficient heat and pressure were applied to deform the web, the
plates were separated and the web was removed from the between
plates. The resulting three-dimensional material having macroscopic
features is illustrated in FIGS. 1A, 1B and 1C and had an effective
bulk thickness of 76 mils (1.93 mm). The method of determining the
effective bulk thickness employed a STARRET.RTM.-type bulk tester
and a pressure (P.sub.w) of 0.05 pounds per square inch (3,450
dynes/cm.sup.2).
EXAMPLE 2
[0082] Example 1 was repeated except the line speed of the forming
wire and TAB was adjusted to approximately 120 ft/min. (36.6
m/min.) to produce a 1.2 ounces per yard (osy) [40.7 grams per
square meter (gsm)] material. The 1.2 osy underbonded material of
Example 2 was thermoformed using the squares pattern as described
in Example 1. The resulting three-dimensional material having
macroscopic features is illustrated in FIGS. 1A, 1B and 1C and had
an effective bulk thickness of 80 mils (2.0 mm).
EXAMPLE 3
[0083] Example 1 was repeated except the line speed of the forming
wire and TAB was adjusted to approximately 58 ft/min. (17.7 m/min.)
to produce a 2.5 ounces per yard (osy) [85 grams per square meter
(gsm)] material. The 2.5 osy underbonded material of Example 3 was
thermoformed using the squares pattern as described in Example 1.
The resulting three-dimensional material having macroscopic
features is illustrated in FIGS. 1A, 1B and 1C and had an effective
bulk thickness of 98 mils (2.5 mm).
EXAMPLE 4
[0084] Example 2 was repeated except that a 1.2 osy underbonded web
was thermoformed into a three-dimensional nonwoven sheet having
stabilized macroscopic topography by embossing a three-dimensional
"triangles" pattern into the web using heat and pressure applied by
the heated interdigitating plates 400 and 450 illustrated in FIGS.
4A and 4B.
[0085] The 1.2 osy (40.7 gsm) underbonded web was thermoformed into
a three-dimensional nonwoven sheet having stabilized macroscopic
topography by embossing a three-dimensional "triangles" pattern
into the web using heat and pressure applied by the heated
interdigitating plates 400 and 450 illustrated in FIGS. 4A and 4B.
Each interdigitating plate included a pattern of triangular
projections that intermeshed with a similar pattern of triangular
projections on the opposing plate. The first plate 400 included a
pattern of triangular tooth-like projections as shown in FIG. 4A.
Each triangular projection 410 on the first plate was approximately
3 millimeters in height and had an equilateral triangular base that
measured approximately 8 millimeters along any one side and
terminated in a equilateral triangular distal top surface 420 that
measured approximately 5 millimeters along any one side. The
projections were spaced apart approximately 9 millimeters from
center to center in both x and y directions. The second plate 450
illustrated in FIG. 4B included a similar pattern of alternating
triangular projections 410 of approximately 4 millimeters in
height, with each projection 410 having an equilateral triangular
base measuring approximately 8.5 millimeters along any one side and
terminating in equilateral triangular distal top surface 420 that
measured approximately 5 millimeters along any one side.
[0086] The resulting three-dimensional material having macroscopic
features is illustrated in FIGS. 5A, 5B and 5C and had an effective
bulk thickness of 120 mils (3.05 mm).
EXAMPLE 5
[0087] Example 3 was repeated except that a 2.5 osy (85 gsm)
underbonded web was thermoformed into a three-dimensional nonwoven
sheet having stabilized macroscopic topography by embossing a
three-dimensional "triangles" pattern into the web using heat and
pressure applied by the heated interdigitating plates 400 and 450
illustrated in FIGS. 4A and 4B. The resulting three-dimensional
material having macroscopic features is illustrated in FIGS. 5A, 5B
and 5C and had an effective bulk thickness of 133 mils (3.38
mm).
[0088] Test Methods
[0089] Basis Weight
[0090] Basis weights of the examples were determined by measuring
and cutting 3 inch (7.6 cm) diameter circular samples from each
sample of material. Each three-inch sample was weighed using a
balance. The weight of a sample was recorded in grams and then
divided by the sample area to provide the basis weight of the
sample. Five samples of each example of material were measured and
weighed using this procedure to provide an averaged basis weight
for each example of nonwoven material.
[0091] Caliper
[0092] Material caliper or thickness of the examples was also
measured. The caliper of an example material was determined by
measuring the thickness of the example material (web) under a 0.05
psi (3,450 dynes/cm.sup.2) load (P.sub.w) using a STARRET.RTM.-type
bulk tester. The thicknesses were measured and recorded in units of
millimeters. Samples of material were cut into 4 inch by 4 inch
(10.2 cm by 10.2 cm) squares. Five samples were cut and measured
under using the above-described procedure and averaged to provide a
mean thickness for each example.
[0093] Bulk Density
[0094] The bulk densities of the nonwoven materials of the Examples
were calculated by dividing the weight per unit area of a sample of
the nonwoven material in grams per square meter (gsm) by the
caliper of the sample of material in millimeters (mm). The web
caliper was measured at 0.05 psi (3,450 dynes/cm.sup.2) as
described in determining caliper. The result was multiplied by
0.001 to convert the value to grams per cubic centimeter (g/cc). A
total of five samples of each Example was evaluated and averaged to
provide the density value.
[0095] Contact Area
[0096] The contact surface areas of the nonwoven materials of the
Examples were also measured. The test equipment included: a
3".times.4" (7.6 cm.times.10.2 cm) sample stage with minimum
thickness of 1/4" inch (6.35 mm), a 12.25".times.5".times.{fraction
(3/16)}" (31 cm.times.12.7 cm.times.0.48 cm) piece of LUCITE.RTM.,
a sample of each material cut into 3".times.4" (7.6 cm.times.10.2
cm) rectangle, a bulk compressometer, a thermometer, a fine pen,
transparency paper cut to a 3".times.4" (7.6 cm.times.10.2 cm)
rectangle, and an rH gauge (hygrometer). All contact areas that
were measured using this procedure are nominal contact areas. That
is the contact areas are defined by the contact that the surface
features have with a flat surface resting on the features. This is
not the sum of the individual fiber areas that are technically in
contact with the flat surface over the projected area of the sample
but include the areas between the individual fibers.
[0097] Initial Measurement and Setup
[0098] 1) Perform test in a controlled environment of
74.+-.4.degree. F. (23.3.+-.2.2.degree. C.) and 50.+-.10% rH.
[0099] 2) Samples shall be prepared from materials that are
representative of materials produced as they are removed from the
forming line and before they are wound or packaged.
[0100] 3) Samples are to be cut from sections of the web that are
uniform and representative of the parent material.
[0101] 4) Three 3".times.4" (7.6 cm.times.10.2 cm) rectangular
samples are cut from the parent material of each Example.
[0102] 5) The initial bulk of each sample is measured using a bulk
compressometer.
[0103] 6) A load is applied and when the reading is stable for 4
seconds the value is recorded. The sample is immediately removed
from the load after the value is recorded.
[0104] Initial Contact Surface/Area
[0105] 7) The 3".times.4" (7.6 cm.times.10.2 cm) sample stage is
placed on top of a flat, level surface.
[0106] 8) The 3".times.4" (7.6 cm.times.10.2 cm) sample is then
lined with the stage and placed on top.
[0107] 9) An initial surface contact area is taken by placing a
flat, clear surface over the top of the sample. A piece of
transparency paper was used for this method.
[0108] 10) The material provides a load of less than 0.003 psi on
the material for the initial reading.
[0109] 11) From the perspective directly above each contacting
topographic surface feature, the perimeter of surface contact is
recorded for the materials by tracing the perimeter with a fine
pen.
[0110] 12) The area of the material contacting the flat surface is
then recorded as the initial contact area. This area is determined
from the tracing performed in step 11.
[0111] 13) This initial contact area is divided by the projected
area of the sample (i.e. 12 square inches) to give a percentage of
contact surface/area for the sample.
[0112] Contact Surface Under Increased Load
[0113] 14) For additional contact area measurements under heavier
loads, a flat rectangular piece of Lucite.RTM. material is placed
over the sample material.
[0114] 15) The center of the rectangular piece of Lucite.RTM.
material is measured.
[0115] 16) A 3".times.4" (7.6 cm.times.10.2 cm) rectangle has been
centered on the rectangular piece of Lucite.RTM. material and
traced. The edges of the traced perimeter are parallel to the edges
of the Lucite.RTM. material rectangle.
[0116] 17) The Lucite.RTM. material is
12.25".times.5".times.{fraction (3/16)}" (31 cm.times.12.7
cm.times.0.48 cm) in dimension and weighs 0.6 lbs (273 grams).
[0117] 18) A piece of transparency paper is placed over the Lucite
material so that the perimeter of the features may be recorded on
the paper.
[0118] 19) From the perspective directly above each contacting
topographic surface feature, the perimeter of surface contact is
recorded using a fine pen for the materials.
[0119] 20) The area of the material contacting the flat surface is
then recorded for the material and the load condition is also
recorded.
[0120] 21)This contact area under load is divided by the projected
area of the sample (i.e. 12 inch.sup.2 or77.4 cm.sup.2) to give a
percentage of contact surface/area for the sample.
[0121] 22) The average true load that the surface features
experience is determined by dividing the weight the plate exerts on
the sample by the area of the sample in contact with the flat load.
E.g. 0.6 lbs on a 12 inch.sup.2 sample that has 20% contact area
would show a 20% contact area at a pressure of 0.25 psi [0.6
lbs/(12 inch.sup.2.times.20%)].
[0122] Additional contact area measurements were made using two
different weights, 1.2 lbs and 6 lbs (0.545 and 2.73 kg). The
contact area is measured until the weight equaled 6 lbs or the
contact area is greater than 90 percent.
[0123] 23) A flat rectangular piece of Lucite.RTM. material is
placed over the sample material.
[0124] 24) The center of the rectangular piece of Lucite.RTM.
material is measured determined.
[0125] 25) A 3".times.4" (7.6 cm.times.10.2 cm) rectangle has been
centered on the rectangular piece of Lucite.RTM. and traced. The
edges of the traced perimeter are parallel to the edges of the
Lucite.RTM. rectangle.
[0126] 26) The Lucite.RTM. is 12.25".times.5".times.{fraction
(3/16)}" (31 cm.times.12.7 cm .times.0.48 cm) in dimension and
weighs 0.6 lbs (273 grams).
[0127] 27) On the edges of the Lucite.RTM. material 0.3 lbs (136.35
grams) of weight are added on each end to provide a total weight of
1.2 lbs of force being placed on the 12 inch.sup.2 web.
[0128] 28) A piece of transparency paper is placed over the Lucite
material so that the perimeter of the features may be recorded on
the paper.
[0129] 29) From the perspective directly above each contacting
topographic surface feature, the perimeter of surface contact is
recorded using a fine pen for the materials.
[0130] 30) The area of the material contacting the flat surface is
then recorded for the material and the load condition is also
recorded.
[0131] 31) This contact area under load is divided by the projected
area of the sample (i.e. 12 inch.sup.2) to give a percentage of
contact surface/area for the sample.
[0132] 32) The average true load that the surface features
experience is determined by dividing the weight the plate exerts on
the sample by the area of the sample in contact with the flat load.
E.g. 6 lbs on a 12 inch.sup.2 sample that has 20% contact area
would show a 20% contact area at a pressure of 2.5 psi [0.6 lbs/(12
inch.sup.2.times.20%)].
[0133] 33) Repeat steps 22-30 where step 26 is modified to provide
a weight of 2.7 lbs (1227 grams) on each side for a total load of 6
lbs (2.72 kg).
[0134] 34) Perform experiment until either the total load on the
sample equals 6 lbs or the nominal contact area that the sample has
with the flat material is greater than 90 percent.
[0135] 35) Take and record the material's (web's) bulk at most 5
minutes after step 29.
[0136] Pressure Applied to Web (P.sub.w)
[0137] Referring to FIG. 2A, the contact area of object P with the
nonwoven 100 is the sum of the cross-hatched areas shown in FIGS.
2A and 2C. The pressure that an object P supported by features 120
transmits to a nonwoven web 100 is measured by dividing the weight
of the supported object P by the flat contiguous area that connects
all of the points of the sheet that directly contact the article.
For example, if an object is supported by sixteen macroscopic
features 100, then the area of the nonwoven web supporting the
object P is the contiguous area (W.sub.p.times.L.sub.p) measured in
a plane parallel to the nonwoven base plane that connects all of
the sixteen features or the parts of the sixteen features that
support the object. In FIG. 2C, the pressure that an object P
supported by the nonwoven transmits to the sheet is measured by
dividing the weight of the supported object P by the flat
contiguous area L.sub.p by W.sub.p beneath the object.
[0138] Average Pressure Observed by Surface Features (P.sub.f)
[0139] The average true load that the surface features experience
is determined by dividing the weight the plate exerts on the sample
by the area of the sample in contact with the flat load. The
average pressure observed by the surface feature P.sub.f is
determined by correcting for the actual area in contact with the
load P.sub.w. This is done by dividing P.sub.w by the percent
contact area.
[0140] Web Volume Measurement Method
[0141] The nonwoven web volume is determined from a measurement of
the void volume inside the web and the volume occupied by the
fibers. Fiber volume is calculated from the weight of the web
divided by fiber density. For webs that possess a high degree of
topography, the internal void volume is measured from a liquid
saturation experiment wherein liquid that is not contained in
internal pores is excluded from the measurement.
[0142] This can be determined using an apparatus based on the
porous plate method reported by Burgeni and Kapur in the Textile
Research Journal, Volume 37, pp. 356-366 (1967), the disclosure of
which is incorporated by reference. The apparatus includes a
movable stage interfaced with a programmable stepper motor, and an
electronic balance controlled by a computer. A control program
automatically moves the stage to a desired height, collects data at
a specified sampling rate until equilibrium is reached, and then
moves the stage to the next calculated height. Controllable
parameters include sampling rates, criteria for equilibrium and the
number of absorption/desorption cycles.
[0143] Data for this analysis was collected using a liquid
containing a surfactant to render the nonwoven web totally wettable
and the measurement was done in desorption mode. That is, the
material was saturated at zero height and the porous plate (and the
effective capillary tension on the sample) was progressively raised
in discrete steps corresponding to the desired capillary radius or
capillary tension. At zero height, a certain amount of liquid
trapped in the interface between the web and the plate exists, due
to the topography of the nonwoven web. As the plate is raised, the
amount of liquid pulled out from the sample was monitored. Readings
at each height were taken every fifteen seconds and equilibrium was
assumed to be reached when the average change of four consecutive
readings was less than 0.005 g. The interfacial liquid (at the
interface between the saturated nonwoven web sample and the porous
plate) is typically removed by raising the plate slightly (0.5-0.7
cm). The internal void volume is expressed as cc/gram.
[0144] The nonwoven web volume is the sum of the internal void
volume measurement described above and the fiber volume.
V.sub.nw=Web volume(cc/g)=Internal void volume+(1/fiber
density)
[0145] Volume of Space Between Liner and a Flat Surface as Measured
Using a Bulk Compressometer
[0146] A circular sample of each Example was taken and the volume
the sample created by separating its top and bottom planes was
determined by multiplying the area of the circle (3") and the
sample's caliper t (t was determined using a STARRET.RTM.-type bulk
tester). This volume will be specified V.sub.p to represent the
volume of space separating the top and bottom planes of the shaped
material.
V.sub.p(cc)=t(cm).times.area of circle(cm.sub.2)
[0147] The nonwoven web volume (V.sub.nw) that was determined using
the method described above was then be subtracted from volume of
space separating the two planes (V.sub.p) to yield the volume of
space not occupied by the web between the two planes (V.sub.s).
V.sub.s(cc)=V.sub.p(cc)-V.sub.nw(cc)
[0148] Because V.sub.nw and V .sub.p were determined using the same
circular sample area, the volume of space not occupied by the web
between the two planes (V.sub.s) can be divided by the area to
determine volume (cc)/area(cm.sup.2) or V.sub.sa.
V.sub.sa(cc/cm.sup.2)=Vs(cc)/area(cm.sup.2)
[0149] The materials used in the examples were generally symmetric.
Therefore, the volume of space per unit area between the top
surface of the liner and the skin V.sub.ls was determined by
dividing V.sub.sa by 2.
V.sub.ls(cc/cm.sup.2)=V.sub.sa(cc)/2
[0150] This assumption is safe for the patterns used in the
Examples because the surface that faces toward the body side
provides the least amount of contact with the body. Therefore,
assuming the sides are symmetric estimates the true volume above
the web.
[0151] Percent Recovery
[0152] The method of determining bulk recovery uses P.sub.w or the
load that is observed by the web. The samples are cut into 3"
circles, and the caliper or thickness of the samples is measured.
The caliper of an example material is determined by measuring the
thickness of the example material (web) under a 0.05 psi (3,450
dynes/cm.sup.2) load (P.sub.w) using a STARRET.RTM.-type bulk
tester. The thickness is measured in units of thousandths of an
inch. The recorded data provides an initial Bulk thickness
(Bulk.sub.0) for the material.
[0153] The sample is then removed and placed under a load P.sub.w
of 3.45 kPa. The load is applied for 5 minutes then removed. The
material is allowed to recovery at ambient conditions for 5
minutes. The caliper of the material is then measured once more
using the bulk tester under the 0.05 psi (3,450 dynes/cm.sup.2)
load (P.sub.w) to provide a final thickness (Bulk.sub.f).
[0154] The final thickness is divided by the initial thickness to
provide a percent recovery of the bulk.
% Recovery=Bulk.sub.f/Bulk.sub.0
[0155] Test Results
[0156] Test results of the tests on the Examples are provided in
Table A below. Failure of rial to provide separation is indicated
by the symbol"--" in Table A.
1 Topographic Liner Properties Bulk Bulk.sub.o Bulk.sub.f Density %
CONTACT AREA UNDER V.sub.ls % Recovery (mils/ (mils/ t (mils/
Example Pattern (g/cc) SPECIFIED LOAD (cc/cm.sup.2)
bulk.sub.f/bulk.sub.o microns) microns) microns) A Flat 0.067 -- --
-- 0.000 100% 8/200 8/200 8/200 1 0.5 osy 0.012 25% -- -- 0.086 80%
76/1930 61/1550 10/250 (17 gsm) @0.2 psi Squares (1.4 kPa) 2 1.2
osy 0.018 30.2% 37% -- 0.087 95% 80/2030 76/1930 16/405 (41 gsm)
@0.17 psi @0.27 psi Squares (1.2 kPa) (1.9 kPa) 3 2.5 osy 0.036 26%
27% 27% 0.096 98% 98/2490 96/2440 20/510 (85 gsm) @0.19 psi @.37
psi @1.86 psi Squares (1.3 kPa) (2.55 kPa) (12.8 kPa) 4 1.2 osy
0.014 23% 37% -- 0.120 94% 120/3050 113/2870 16/405 (41 gsm) @0.22
psi @0.27 psi Triangles (1.5 kPa) (1.9 kPa) 5 2.5 osy 0.025 20% 20%
26% 0.138 96% 133/3380 128/3250 20/510 (85 gsm) @0.25 psi @0.51 psi
@1.91 psi Triangles (1.7 kPa) (3.5 Kpa) (13.2 kPa)
[0157] Thus, it is apparent that there has been provided, in
accordance with the invention, a nonwoven fabric having macroscopic
surface features. While the invention has been described in
conjunction with specific embodiments thereof, it is evident that
many alternatives, modifications, and variations will be apparent
to those skilled in the art in light of the foregoing description.
Accordingly, it is intended to embrace all such alternatives,
modifications, and variations as fall within the spirit and broad
scope of the appended claims.
* * * * *