Molecular sieve abstract
A method for distributing a zeolite, including molecular sieve,
powder having a median particle size of less than about 350 microns
includes controlling the moisture content of the zeolite particles
to greater than about 3 percent and thereafter refining the powder
to reduce the size of agglomerated clusters.
Molecular sieve claims
We claim:
1. A method for distributing a zeolite powder, comprising:
providing a powder comprising clusters of zeolite particles, the
zeolite particles having a median particle size of less than about
350 microns;
controlling the moisture content of the zeolite particles to greater
than about 3 percent; and
thereafter refining the powder to reduce the size of the clusters
wherein refining comprises vibrating the powder.
2. The method of claim 1 wherein vibrating comprises sifting the
powder through a perforated surface.
3. The method of claim 1 wherein the moisture content is controlled
to greater than about 7 percent.
4. The method of claim 1 wherein the moisture content is controlled
to between about 8 and about 10 percent.
5. The method of claim 1 3 or 4 further comprising adding moisture
to the zeolite powder to elevate the moisture content.
6. The method of claim 1 3 or 4 wherein the zeolite particles
have a median particle size of less than about 100 microns.
7. The method of claim 6 wherein the zeolite particles have a
median particle size of less than about 50 microns.
8. The method of claim 1 3 or 4 wherein refining reduces the
size of the clusters to a mean diameter of less than about 1500
microns.
9. The method of claim 1 3 or 4 wherein refining reduces the
size of the clusters to a mean diameter of less than about 1100
microns.
10. The method of claim 1 3 or 4 further comprising distributing
the powder onto a carrier substrate.
11. The method of claim 10 further comprising marrying the carrier
substrate with a cover substrate to sandwich the powder between
the carrier and cover substrates.
12. The method of claim 11 wherein the carrier and cover substrates
comprise gas permeable materials.
13. The method of claim 10 further comprising applying adhesive
to the carrier substrate.
14. A method for distributing a molecular sieve powder, comprising:
providing a powder comprising clusters of molecular sieve particles,
the molecular sieve particles having a median particle size of less
than about 350 microns;
controlling the moisture content of the molecular sieve particles
to greater than about 3 percent; and
thereafter refining the powder to reduce the size of the clusters
wherein refining comprises vibrating the powder.
15. The method of claim 14 wherein vibrating comprises sifting
the powder through a perforated surface.
16. The method of claim 14 wherein the moisture content is controlled
to greater than about 7 percent.
17. The method of claim 14 wherein the moisture content is controlled
to between about 8 and about 10 percent.
18. The method of claim 14 16 or 17 further comprising adding
moisture to the molecular sieve powder to elevate the moisture content.
19. The method of claim 14 16 or 17 wherein the molecular sieve
particles have a median particle size of less than about 100 microns.
20. The method of claim 19 wherein the molecular sieve particles
have a median particle size of less than about 50 microns.
21. The method of claim 14 16 or 17 wherein refining reduces
the size of the clusters to a mean diameter of less than about 1500
microns.
22. The method of claim 14 16 or 17 wherein refining reduces
the size of the clusters to a mean diameter of less than about 1100
microns.
23. The method of claim 14 16 or 17 further comprising distributing
the powder onto a carrier substrate.
24. The method of claim 23 further comprising marrying the carrier
substrate with a cover substrate to sandwich the powder between
the carrier and cover substrates.
25. The method of claim 24 wherein the carrier and cover substrates
comprise gas permeable materials.
26. The method of claim 23 further comprising applying adhesive
to the carrier substrate.
27. A method for distributing a zeolite powder, comprising:
providing a powder comprising clusters of zeolite particles, the
zeolite particles having a median particle size of less than about
350 microns;
controlling the moisture content of the zeolite particles to greater
than about 3 percent; and
thereafter refining the powder to reduce the size of the clusters
wherein refining comprises extruding and vibrating the powder.
28. The method of claim 27 wherein refining comprises:
screening the powder to form clusters having a mean diameter of
less than 1500 microns; and
vibrating the screened powder to further reduce the mean diameter.
29. The method of claim 27 wherein the moisture content is controlled
to greater than about 7 percent.
30. The method of claim 27 wherein the moisture content is controlled
to between about 8 and about 10 percent.
31. The method of claim 27 29 or 30 further comprising adding
moisture to the zeolite powder to elevate the moisture content.
32. The method of claim 27 29 or 30 wherein the zeolite particles
have a median particle size of less than about 100 microns.
33. The method of claim 32 wherein the zeolite particles have
a median particle size of less than about 50 microns.
34. The method of claim 27 29 or 30 wherein refining reduces
the size of the clusters to a mean diameter of less than about 1500
microns.
35. The method of claim 27 29 or 30 wherein refining reduces
the size of the clusters to a mean diameter of less than about 1100
microns.
36. The method of claim 27 29 or 30 further comprising distributing
the powder onto a carrier substrate.
37. The method of claim 36 further comprising marrying the carrier
substrate with a cover substrate to sandwich the powder between
the carrier and cover substrates.
38. The method of claim 37 wherein the carrier and cover substrates
comprise gas permeable materials.
39. The method of claim 36 further comprising applying adhesive
to the carrier substrate.
40. A method for distributing a molecular sieve powder, comprising:
providing a powder comprising clusters of molecular sieve particles,
the molecular sieve particles having a median particle size of less
than about 350 microns;
controlling the moisture content of the molecular sieve particles
to greater than about 3 percent; and
thereafter refining the powder to reduce the size of the clusters
wherein refining comprises extruding and vibrating the powder.
41. The method of claim 40 wherein refining comprises:
screening the powder to form clusters having a mean diameter of
less than 1500 microns; and
vibrating the screened powder to further reduce the mean diameter.
42. The method of claim 40 wherein the moisture content is controlled
to greater than about 7 percent.
43. The method of claim 40 wherein the moisture content is controlled
to between about 8 and about 10 percent.
44. The method of claim 40 42 or 43 further comprising adding
moisture to the molecular sieve powder to elevate the moisture content.
45. The method of claim 40 42 or 43 wherein the molecular sieve
particles have a median particle size of less than about 100 microns.
46. The method of claim 45 wherein the molecular sieve particles
have a median particle size of less than about 50 microns.
47. The method of claim 40 42 or 43 wherein refining reduces
the size of the clusters to a mean diameter of less than about 1500
microns.
48. The method of claim 40 42 or 43 wherein refining reduces
the size of the clusters to a mean diameter of less than about 1100
microns.
49. The method of claim 40 42 or 43 further comprising distributing
the powder onto a carrier substrate.
50. The method of claim 49 further comprising marrying the carrier
substrate with a cover substrate to sandwich the powder between
the carrier and cover substrates.
51. The method of claim 50 wherein the carrier and cover substrates
comprise gas permeable materials.
52. The method of claim 49 further comprising applying adhesive
to the carrier substrate.
53. A method for distributing a zeolite powder, comprising:
providing a powder comprising clusters of zeolite particles, the
zeolite particles having a median particle size of less than about
350 microns;
controlling the moisture content of the zeolite particles to greater
than about 3 percent;
refining the powder to reduce the size of the clusters;
distributing the powder onto a carrier substrate; and,
marrying the carrier substrate with a cover substrate to sandwich
the powder between the carrier and cover substrates.
54. The method of claim 53 wherein the carrier and cover substrates
comprise gas permeable materials.
55. A method for distributing a molecular sieve powder, comprising:
providing a powder comprising clusters of molecular sieve particles,
the molecular sieve particles having a median particle size of less
than about 350 microns;
controlling the moisture content of the molecular sieve particles
to greater than about 3 percent;
refining the powder to reduce the size of the clusters;
distributing the powder onto a carrier substrate; and,
marrying the carrier substrate with a cover substrate to sandwich
the powder between the carrier and cover substrates.
56. The method of claim 55 wherein the carrier and cover substrates
comprise gas permeable materials.
57. A method for distributing a zeolite powder, comprising:
providing a powder comprising clusters of zeolite particles, the
zeolite particles having a median particle size of less than about
350 microns;
controlling the moisture content of the zeolite particles to greater
than about 3 percent;
refining the powder to reduce the size of the clusters;
distributing the powder onto a carrier substrate; and,
applying adhesive to the carrier substrate.
58. A method for distributing a molecular sieve powder, comprising:
providing a powder comprising clusters of molecular sieve particles,
the molecular sieve particles having a median particle size of less
than about 350 microns;
controlling the moisture content of the molecular sieve particles
to greater than about 3 percent;
refining the powder to reduce the size of the clusters;
distributing the powder onto a carrier substrate; and,
applying adhesive to the carrier substrate.
59. A method for making an absorbent article, comprising:
providing a powder comprising clusters of zeolite particles, the
zeolite particles having a median particle size of less than about
350 microns;
controlling the moisture content of the zeolite particles to greater
than about 3 percent;
thereafter refining the powder to reduce the size of the clusters;
providing a moisture barrier, a bodyside liner and an absorbent
assembly;
disposing the absorbent assembly between the moisture barrier and
the bodyside liner;
distributing the refined powder between the moisture barrier and
the bodyside liner; and
bonding the bodyside liner to the moisture barrier.
60. The method of claim 59 wherein the powder is distributed at
an add-on of about 0.1 to about 50 grams per square meter.
61. The method of claim 59 wherein distributing comprises distributing
the powder onto a carrier substrate and disposing the carrier substrate
between the moisture barrier and the bodyside liner.
62. The method of claim 59 60 or 61 further comprising distributing
the powder onto a carrier.
63. A method for making an absorbent article, comprising:
providing a powder comprising clusters of molecular sieve particles,
the molecular sieve particles having a median particle size of less
than about 350 microns;
controlling the moisture content of the molecular sieve particles
to greater than about 3 percent;
thereafter refining the powder to reduce the size of the clusters;
providing a moisture barrier, a bodyside liner and an absorbent
assembly;
disposing the absorbent assembly between the moisture barrier and
the bodyside liner;
distributing the refined powder between the moisture barrier and
the bodyside liner; and
bonding the bodyside liner to the moisture barrier.
64. The method of claim 63 wherein the powder is distributed at
an add-on of about 0.1 to about 50 grams per square meter.
65. The method of claim 63 wherein distributing comprises distributing
the powder onto a carrier substrate and disposing the carrier substrate
between the moisture barrier and the bodyside liner.
66. The method of claim 63 64 or 65 further comprising distributing
the powder onto a carrier.
Molecular sieve description
BACKGROUND OF THE INVENTION
The present invention relates to a method for handling powderous
materials comprising fine particulate. More particularly, the invention
pertains a method for distributing a zeolite, such as a molecular
sieve powder.
Zeolites, such as molecular sieves, have a crystalline structure
that is particularly suited for adsorbing odorous materials. Zeolites
are both naturally occurring and synthetically produced. Zeolites
are inherently statically charged insulators that electrostatically
attract the adsorbates. In addition to driving the absorptive forces,
however, the static charge of zeolites, more specifically molecular
sieves also lead to material handling difficulties. In the past,
these difficulties have rendered the use of zeolites, including
molecular sieves, uneconomical and/or problematic for many applications.
Static electricity causes zeolite powder to agglomerate during
processing into relatively large, non-uniform clusters having substantial
integrity. These clusters reduce the cost effectiveness of the final
product and the performance efficiency of the zeolite by causing
a very high degree of powder weight add-on variability and non-uniform
deposition. Additionally, an unacceptably large amount of the statically
charged particles tend to become airborne and contaminate the working
environment. Due to their electrical charge, the zeolite particles
cannot thereafter be easily removed from working surfaces by airjets
or vacuum.
Previous attempts to manage the foregoing processing problems associated
with zeolites have focused on increasing the particle size, either
by increasing the size of the zeolite itself or by bonding the zeolite,
such as a molecular sieve, to another substance. While increasing
the particle size may lessen somewhat weight add-on variability
and reduce deposition non-uniformity, this approach remains unsatisfactory.
The larger zeolites or zeolite composites are cost prohibitive for
many applications and do not significantly reduce airborne dust
contamination.
Therefore, what is lacking and needed in the art is an economical
approach to distributing zeolite, and more specifically molecular
sieve, powders.
SUMMARY OF THE INVENTION
In response to the discussed deficiencies in the prior art, a new
and economical approach to distributing zeolite, and more specifically
molecular sieve, powders has been developed. In one embodiment,
a method for distributing a zeolite powder includes the steps of:
providing a powder comprising clusters of zeolite particles, which
particles have a median particle size of less than about 350 microns;
controlling the moisture content of the molecular sieve particles
to greater than about 3 percent; and thereafter refining the powder
to reduce the size of the clusters.
The refining is effective to reduce the size of powder clusters
as a result of lower static levels obtained at the indicated moisture
content. In particular embodiments, the moisture content is controlled
to greater than about 4 percent, and particularly greater than about
7 percent. In the manufacture of absorbent articles, the moisture
content is controlled in a range between about 6 and about 15 percent,
particularly between about 7 and about 12 percent, and more particularly
between about 8 and about 10 percent, such as about 9 percent, to
reduce static and improve refining without degrading the effectiveness
of the zeolite. The refining may be accomplished in a variety of
ways, with particularly efficient methods including extruding and/or
vibrating the powder. Powder clusters having a mean diameter of
less than about 1500 microns, and particularly less than about 1100
microns, are believed to be particularly well suited for use in
absorbent articles.
Thus, another aspect relates to a method for making an absorbent
article. The method includes the steps of: providing a powder comprising
clusters of zeolite, such as molecular sieve, particles, which particles
have a median particle size of less than about 350 microns; controlling
the moisture content of the zeolite particles to greater than about
3 percent; thereafter refining the powder to reduce the size of
the clusters; providing a moisture barrier, a bodyside liner and
an absorbent assembly; disposing the absorbent assembly between
the moisture barrier and the bodyside liner; distributing the refined
powder between the moisture barrier and the bodyside liner; and
bonding the bodyside liner to the moisture barrier.
Numerous features and advantages of the present invention will
appear from the following description. In the description, reference
is made to the accompanying figures which illustrate preferred embodiments
of the invention. Such embodiments do not represent the full scope
of the invention. Reference should therefore be made to the claims
herein for interpreting the full scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 representatively shows a schematic illustration of a method
for processing a zeolite, such as molecular sieve, powder.
FIG. 2 representatively shows a perspective view of equipment used
in one embodiment of the method for processing zeolite, such as
molecular sieve, powders.
FIG. 3 representatively shows an enlarged perspective view of alternative
equipment used in the method for processing zeolite, such as molecular
sieve, powders.
FIG. 4 representatively shows an absorbent article containing zeolite,
such as molecular sieve, particles that have been distributed according
to the present method.
FIG. 5 representatively shows a section view taken generally from
the plane of the line 5--5 in FIG. 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A method for distributing powderous materials comprising fine particulates
such as zeolites is schematically illustrated in FIG. 1. The illustrated
method distributes a zeolite (such as a bulk molecular sieve) powder
onto a carrier (including carrier substrate) for eventual incorporation
in an absorbent article. Alternatively, however, the method may
be used to distribute the powder directly into a finished product.
Further, the method pertains to the use of a zeolite in other types
products such as tissues, wipers, medical garments, other absorbent
articles such as diapers, training pants, feminine care products,
other adult incontinence products, or the like.
A powder comprising zeolite particles is provided from a source
20 of zeolite powder. The moisture content of the zeolite particles
is desirably controlled to greater than about 3 percent. The zeolite
particles are desirably supplied from the source 20 with the desired
moisture content. Alternatively, the powder may be routed to an
optional moisture station 22 to raise or lower the moisture content
of the zeolite powder to the desired level. The powder is thereafter
processed at a refining station 24 to reduce the size of clusters
of the zeolite particles. The term "clusters" is used
herein to refer to agglomerations of zeolite particles which result
in part from their static charge. The refined powder may then be
distributed onto an intermediate carrier, carrier substrate, or
directly into a finished product at a deposition station 26.
When entering the refining station 24 the zeolite particles desirably
have a moisture content of greater than about 3 percent, particularly
greater than about 4 percent, and more particularly greater than
about 7 percent. In the manufacture of absorbent articles, the moisture
content is controlled within a range of from about 6 to about 15
percent, particularly from about 7 to about 12 percent, and even
more particularly from about 8 to about 10 percent, for improved
handling and distribution.
For purposes of the present invention, the term "zeolite"
refers to a microporous crystalline structure having pore diameters
large enough to absorb at least one odorous organic molecular species,
or compositions containing such structures. Such structures are
both naturally occurring and synthetically produced. Such a structure
is typically composed of primary structural units, MO4 tetrahedra,
combined into secondary structural units, such as a polyhedra. M
is typically, although not necessarily for purposes hereof comprised
at least one of aluminum, and/or silicon. M may also be comprised
of sodium, magnesium, potassium, calcium, strontium, barium, titanium,
zinc, iron, cobalt, and manganese.
A method for distributing powderous materials comprising fine particulates,
specifically molecular sieves, is also schematically illustrated
in FIG. 1. The illustrated method distributes a bulk molecular sieve
powder onto a carrier (including carrier substrate) for eventual
incorporation in an absorbent article. Alternatively, however, the
method may be used to distribute the powder directly into a finished
product. Further, the method pertains to the use of a molecular
sieve in other types products such as tissues, wipers, medical garments,
other absorbent articles such as diapers, training pants, feminine
care products, other adult incontinence products, or the like.
A powder comprising molecular sieve particles is provided from
a source 20 of molecular sieve powder. The moisture content of the
molecular sieve particles is desirably controlled to greater than
about 7 percent. The molecular sieve particles are desirably supplied
from the source 20 with the desired moisture content. Alternatively,
the powder may be routed to an optional moisture station 22 to raise
or lower the moisture content of the molecular sieve powder to the
desired level. The powder is thereafter processed at a refining
station 24 to reduce the size of clusters of the molecular sieve
particles. The term "clusters" is used herein to refer
to agglomerations of molecular sieve particles which result in part
from their static charge. The refined powder may then be distributed
onto an intermediate carrier substrate or directly into a finished
product at a deposition station 26.
When entering the refining station 24 the molecular sieve particles
desirably have a moisture content of greater than about 3 percent,
particularly greater than about 4 percent, and more particularly
greater than about 7 percent. In the manufacture of absorbent articles,
the moisture content is controlled within a range of from about
6 to about 15 percent, and even more particularly from about 8 to
about 10 percent, for improved handling and distribution.
For purposes of the present invention, the term "molecular
sieve" refers to a microporous crystalline structure having
pore diameters large enough to adsorb at least one odorous organic
molecular species, or compositions containing such structures. In
its anhydrous form, such structure is typically composed of an orderly
arrangement of corner-sharing MO2 tetrahedra, in which "M"
has historically although not necessarily for purposes hereof comprised
at least one of aluminum and/or silicon.
One suitable procedure for determining the moisture content of
zeolite (including molecular sieves) particles is a gravimetric
procedure referred to as a loss on ignition test. The test includes
heating a crucible in a muffle furnace for 1 hour at 1000 degrees
Celsius; cooling the crucible in a desicator for 1 hour; recording
the empty weight of the cooled crucible; placing approximately 1
gram of zeolite particles in the crucible; recording the initial
combined weight of the crucible and particles; heating the crucible
and particles in the muffle furnace for 1 hour at 1000 degrees Celsius;
cooling the crucible and particles in the desicator for 1 hour;
and recording the final combined weight of he crucible and particles.
The initial combined weight minus the empty weight is the beginning
weight of the zeolite particles. The final combined weight minus
the empty weight is the ending weight of the particles. The moisture
content of the zeolite particles is the beginning weight minus the
ending weight, divided by the beginning weight and expressed as
a percentage. An approximated value for the loss on ignition test
can be determined using a moisture analyzer available for Sartorious
AG Gottingen of Germany and identified as united MA-30.
Exemplary zeolite materials are disclosed in U.S. Pat. Nos. 4795482
issued Jan. 3 1989 to Gioffre et al.; 4826497 issued May 2
1989 to Marcus et al.; 5013335 issued May 71991 to Marcus;
and, 5152972 issued Oct. 6 1992 to Gier. ZEOLITE SYNTHESIS ACS
Symposium Series 398 Eds. M. L. Occelli and H. E. Robson (1989)
pgs 2-7; MOLECULAR SIEVES, Encyclopedia of Chemical Technology,
Vol.16 pgs 888-925 4th Ed. (1995); MOLECULAR SIEVE, Encyclopedia
of Science & Technology, Vol. 11 pgs 357-358 7th Ed. (1992);
ZEOLITE, Encyclopedia of Science & Technology, Vol. 19 pgs
619-620 7th Ed. (1992); ZEOLITE MOECULAR SIEVES, Structure, Chemistry
and Use, by D. W. Breck, John Wiley & Sons (1974) pgs 245-250
313-314 and 348-352.
Exemplary molecular sieve materials are disclosed in U.S. Pat.
Nos. 4795482 issued Jan. 3 1989 to Gioffre et al.; 4826497
issued May 2 1989 to Marcus et al.; 5013335 issued May 7 1991
to Marcus; and, 5152972 issued Oct. 6 1992 to Gier; the disclosures
of which are incorporated herein by reference. Molecular sieves
for use with the present distribution method are available from
commercial vendors such as UOP, which has offices in Des Plaines,
Ill., USA. Particular molecular sieves from UOP include those referred
to by the trademark ABSCENTS and the trade designation #3000 or
#3318 although any other small particle size molecular sieve composition
may be suitable as well.
The powder desirably comprises individual zeolite particles having
a median particle size of less than 350 microns, particularly less
than 200 microns, more particularly less than about 100 microns,
and most particularly less than about 50 microns. In one particular
embodiment, the zeolite has a particle size distribution from 1.4
to 44 microns with a median particle size of about 3.7 microns.
One suitable procedure for determining the particle size of a zeolite
is a standard sieve analysis, although other techniques such as
optical microscopy, image analysis, optical or resistivity zone
sensing, or the like may also be appropriate depending upon the
general size of the particles. The procedure for measuring particle
size takes into consideration individual zeolite particles or agglomerates
of such particles.
Applicants have discovered that improved handling and distribution
of zeolite particles is possible when the moisture content is controlled
to relatively high levels. By controlling the moisture content of
the zeolite particles to the indicated levels, the powder becomes
conductive and thus discharges most of its static charge. This can
be visually observed by a reduction in the occurrence of sparks
that would otherwise be present, and by less movement of the particles
as a consequence of objects, such as a person's hand, moving in
close proximity to the particles. The reduced static levels diminish
the propensity of the zeolite particles to form clusters and limit
the integrity of the clusters to levels at which separation, for
example by mechanical means, is economically feasible. More specifically,
the powder can be separated into a finer and more uniform final
particulate. This improved zeolite distribution permits a cost effective
utilization of the odor control material because the finer distribution
provides better odor adsorption performance. From a processing standpoint,
the reduced levels of static also lessen airborne contamination,
referred to as dusting; decrease buildup of the material on working
surfaces; and permit easier removal of any such buildups by airjets
or vacuum.
In one embodiment, the method for distributing a zeolite powder
30 may be carried out using the equipment illustrated in FIG. 2.
In general, the method utilizes a metering device 32 that receives
the zeolite powder 30 from a source 20 (FIG. 1) and delivers it
to an extrusion device 34. The extrusion device 34 separates the
powder 30 into generally uniform diameter particulate material 36
including clusters and individual particles that are then delivered
to a vibration device 38. The vibration device 38 is operable to
further separate the clusters into smaller sizes and deliver the
powder to a deposition station 26 for incorporation into a product.
The illustrated metering device 32 comprises a volumetric feeder
including a bulk solids agitating hopper 40 a nozzle 42 and a
rotating helix (screw) 44 that extends at least partially into the
interior of the hopper 40 and transports the zeolite powder 30 out
of the hopper through the nozzle 42. The hopper 40 desirably comprises
a liner (not shown) formed of rubber or the like and an agitator
mechanism (not shown) to shake the liner and cause the powder 30
to drop toward the rotating helix 44. Suitable metering devices
32 are available from AccuRate Inc. of Whitewater, Wis., USA, under
the trademark ACCURATE. One such system is a 604 Series volumetric
feeder using dual 1/4 horsepower motors for separate agitation speed
control and a 1 inch square stock helix having a spiral that is
open in the center to prevent powder buildup on the center shaft.
For applications involving absorbent articles, the metering device
32 may for example supply the zeolite powder 30 at a feedrate of
at least 50 grams per minute, such as about 55 grams per minute.
Alternative metering devices such as a weight loss feeder, a flatstock
helix, an auger, or the like may also be used.
The extrusion device 34 comprises a screening mechanism such as
1/16 inch mesh rectangular screen (1.59 mm). Selection of a screen
size should consider the desired particle size exiting the screen
in combination with the metering device power and desired system
throughput. This screen desirably provides a generally uniform diameter
powder particulate size. Upon exiting the extrusion device 34 the
particulate material 36 desirably has a generally uniform average
diameter of less than about 1500 microns, and particularly less
than about 1100 microns, for improved performance. It may be beneficial
to intentionally agglomerate the zeolite particles into generally
uniform diameter clusters by extrusion or other means in order to
improve the overall uniformity and distribution of clusters at the
deposition station 26.
Other mechanisms such as a sifter or the like may alternatively
be used to refine the zeolite powder 30 into appropriately sized
particulate material 36. From the screen, the clusters and individual
particles 36 fall by gravity or are transported by other suitable
means to the vibration device 38.
In the illustrated embodiment, the vibration device 36 comprises
a vibrating horn 50 a basket 52 disposed on the vibrating horn,
and a funnel 54 to direct particulate material 36 exiting the vibrating
horn 50. The vibrating horn 50 has opposite entry and exit ends
56 and 58 between which particulate material 36 travels prior to
exiting through the optional funnel 54. In the illustrated embodiment,
the vibrating horn 50 narrows from about 3 inches (7.6 cm) at the
entry end 56 to about 1.5 inch (3.8 cm) at the entrance to the funnel
54. The hopper 40 and the vibrating horn 50 are both mounted on
a frame 63 which is connected to a fixed structural support (not
shown). The funnel 54 is used to control the direction of the particulate
material 36.
The basket 52 is mounted at the entry end 56 of the vibrating horn
50 so that particulate material 36 exiting the extrusion device
34 is deposited in the basket 52. The basket 52 is desirably formed
of a perforated material such as metal or the like. The basket 52
functions to accumulate particulate material 36 and eliminate surges
of material; widen the distribution pattern of the particulate material;
and sift the particulate material through the perforations onto
the vibrating horn 50 to evenly distribute the particulate material
36 across the width of the basket 52.
The vibrating horn 50 comprises an actuator 60 that is operably
connected to a power source (not shown) and adapted to vibrate the
horn. One suitable actuator 60 is a 20 watt vibrator operating at
3600 cycles per minute. The design of the horn 50 and the operating
characteristics of the actuator 60 are selected so that the particulate
material 36 is transported through the basket 52 and to the exit
end 58 of the vibrating horn.
At the deposition station 26 the particulate material 36 exits
the funnel 54 and is deposited onto a substantially continuous moving
carrier substrate 70. In an alternative embodiment, the particulate
material 36 at the deposition station 26 is deposited onto a substantially
continuous moving carrier, including but not limited to machinery
such as screens, belts, and vibrating horns. Optionally, an adhesive
72 is deposited onto the carrier substrate 70 by an adhesive die
head 74 either prior to or after placement of the particulate material
36 on the carrier substrate. Also optionally, a substantially continuous,
moving cover substrate 76 may be married with the carrier substrate
70 at nip rolls 78 rotating in the direction of arrows 79 to sandwich
the particulate material 36 between the carrier and cover substrates.
The carrier and cover substrates 70 and 76 suitably comprise gas
permeable materials such as nonwovens or apertured films. In one
particular embodiment the substrates 70 and 76 comprise cellulosic
tissue wraps each having a basis weight of 26 grams per square meter
(gsm).
The adhesive 72 functions to bond the particulate material 36 and
the cover substrate 76 to the carrier substrate 70 thus forming
a composite 80 moving in the direction of arrow 82. The adhesive
72 is desirably applied in a meltspray application that bonds the
zeolite particles in place but does not block volatile materials
from reaching the crystalline structure of the zeolite. One suitable
adhesive die unit for dispensing the adhesive is available from
J and M Laboratories, Inc. of Dawsonville, Ga., USA, and is identified
as a MAMBI DURAFIBER die, Model DF-12-16. The particular adhesive
72 is desirably a hot melt adhesive that does not significantly
contaminate the efficacy of the zeolite. Suitable adhesives are
available from Ato Findley Adhesives from Wauwatosa, Wis., USA,
under the trade designation H-2088 or National Starch and Chemical
Corporation of Bridgewater, N.J., USA, under the trade designation
34-5610.
In particular embodiments, the carrier and cover substrates 70
and 76 may be transported at speeds of over 300 feet per minute
(fpm), for example about 333 fpm. Further, the resultant composite
80 may include zeolite add-on levels of about 0.1 to about 50 gsm
with hot melt adhesive add-on levels of about 3 to about 10 gsm.
More particularly, the zeolite add-on level may range between about
4 to about 50 gsm. Suitable adhesion of the zeolite to the substrates
and the substrates to one another is believed possible at about
3 to about 5 gsm melt spray add-ons. The wide ranges of zeolite
and adhesive add-ons yield a large matrix of odor controlling material
composites 80 that are capable of being incorporated into personal
care absorbent articles or other products.
Alternative refining equipment is illustrated in FIG. 3. Similar
to the equipment of FIG. 2 the zeolite powder 30 is processed through
a metering device 32 (not shown) having a nozzle 42 and a rotating
helix 44. Rather than the extrusion device 34 and vibrating horn
50 though, in this embodiment refining is accomplished by vibrating
the nozzle 42 and causing the particulate material 36 (not shown)
to be distributed through a slot 68 in the nozzle. In particular,
a vibration device 66 is operably connected to a power source (not
shown) and adapted to vibrate the nozzle 42. The size of the slot
68 may be selected to provide the desired spreading pattern, and
may be adjustable. In one particular embodiment, the slot 68 has
a length of about 1.5 inches (3.81 cm) and a height of 0.375 inch
(0.95 cm). The particulate material 36 exiting the slot 68 desirably
have mean diameters of the same magnitude as referenced above in
relation to the extrusion device of FIG. 2.
By way of illustration, one exemplary absorbent article utilizing
a zeolite composite 80 is illustrated by an incontinence pad 100
in FIGS. 4 and 5. The pad 100 includes a moisture barrier 102 a
bodyside liner 104 a retention portion in the form of an absorbent
assembly 106 disposed between the moisture barrier and bodyside
liner, and a molecular sieve composite 80 disposed between the absorbent
assembly and the bodyside liner. Desirably although not necessarily,
the pad 100 may also include side elastic members 108 and a liquid
acquisition/distribution layer 110. The pad 100 desirably further
comprises a means for holding the pad 100 in position during use
(not shown). For example, the pad 100 may comprise a garment attachment
adhesive, a body attachment adhesive, belts, straps, wings, mechanical
fasteners, and/or other suitable fastening devices to secure the
pad in position to absorb body exudates.
With particular reference to FIG. 4 the illustrated pad 100 defines
a longitudinal axis or center line represented by arrow 130 which
generally corresponds to the greatest planar dimension of the product.
The pad 100 has opposite, longitudinal end edges 132 and opposite,
longitudinal side edges 134 that extend between the longitudinal
end edges. The longitudinal side edges 134 are shown as generally
straight, but optionally, may be curvilinear and contoured, for
example so that the pad 100 is generally hourglass shaped.
The moisture barrier 102 and bodyside liner 104 are desirably longer
and wider than the absorbent assembly 106 and the composite 80 so
that the peripheries of the moisture barrier and bodyside liner
may be bonded together using ultrasonic bonds, thermal bonds, adhesives,
or other suitable means. Additionally, the absorbent assembly 106
and the composite 80 may be bonded directly to the moisture barrier
102 and the bodyside liner 104 using ultrasonic bonds, thermal bonds,
adhesives, or other suitable means. As used herein, the term "bonded"
refers to the joining, adhering, connecting, attaching, or the like,
of two elements. Two elements will be considered to be bonded together
when they are bonded directly to one another or indirectly to one
another, such as when each is directly bonded to intermediate elements.
The moisture barrier or backsheet 102 desirably comprises a material
that is formed or treated to be liquid impermeable. Alternatively,
the moisture barrier 102 may comprise a liquid permeable material
and other suitable means may be provided to impede liquid movement
away from the absorbent assembly 106 such as a liquid impermeable
layer (not shown) associated with the absorbent assembly. The moisture
barrier 102 may also be gas permeable over either all or part of
its surface area.
The moisture barrier 102 may comprise a single layer of material
or a laminate of two or more separate layers of material. Suitable
moisture barrier materials include films, wovens, nonwovens, laminates
of films, wovens, and/or nonwovens, or the like. For example, the
moisture barrier 102 may comprise a thin, substantially liquid impermeable
web or sheet of plastic film such as polyethylene, polypropylene,
polyvinyl chloride or similar material. The moisture barrier material
may be transparent or opaque and have an embossed or matte surface.
One particular material for the moisture barrier 102 is a polyethylene
film that has a nominal thickness of about 0.028 millimeter and
a systematic matte embossed pattern, and that has been corona treated
on both sides.
The absorbent assembly 106 comprises materials adapted to absorb,
distribute, and retain liquid waste, and may be in the form of a
single or multi-layered structure. The absorbent assembly 106 may
comprise various absorbent materials, such as an air-formed batt
of cellulosic fibers (i.e., wood pulp fluff) or a coform material
composed of a mixture of cellulosic fibers and synthetic polymer
fibers. The absorbent assembly 106 may include 0-95 weight percent
of organic or inorganic high-absorbency materials to increase the
absorbency of the assembly. As used herein, the term "high-absorbency
materials" refers to materials that are capable of absorbing
at least about 15 and desirably more than 25 times their weight
in water. Suitable high-absorbency materials are described in U.S.
Pat. Nos. 4699823 issued Oct. 13 1987 to Kellenberger et al.
and 5147343 issued Sep. 15 1992 to Kellenberger, which are incorporated
herein by reference. High-absorbency materials are available from
various commercial vendors, such as The Dow Chemical Company; Hoechst
Celanese Corporation; Chemische Fabrik Stockhausen, GMBH; and Allied
Colloids, Inc.
The zeolite composite 80 is shown in particularly large scale in
order to illustrate the presence of the molecular sieve particulate
material 36. The composite 80 may be cut or trimmed as needed along
with the absorbent assembly 106 for example to provide the hourglass
shaped structure as illustrated in FIGS. 4 and 5. Alternatively,
the composite 80 may be sized to reside within the pad 100 without
being trimmed during assembly of the pad 100.
The acquisition/distribution layer 110 is desirably provided to
help decelerate and diffuse surges of liquid that may be introduced
into the absorbent assembly 106. The acquisition/distribution layer
110 may be positioned subjacent the bodyside liner 104 as illustrated,
or alternatively disposed on the inwardly facing, bodyside surface
of bodyside liner. Suitable configurations of the acquisition/distribution
layer 110 are described in U.S. Pat. No. 5192606 issued Mar. 9
1993 to D. Proxmire et al.; U.S. Pat. No. 5486166 issued Jan.
23 1996 to Ellis et al.; U.S. Pat. No. 5490846 issued Feb. 13
1996 to Ellis et al.; and U.S. patent application Ser. No. 096654
of W. Hanson et al., titled "Thin Absorbent Article Having
Rapid Uptake Of Liquid," and filed Jul. 22 1993 now U.S. Pat.
No. 5509915; the disclosures of which are hereby incorporated
by reference. By way of illustration, the acquisition/distribution
layer 110 may comprise a through-air bonded carded web composed
of a blend of 40% of 6 denier polyester fibers, commercially available
from Hoechst Celanese Corporation, and 60% of 3 denier polypropylene/polyethylene
side-by-side bicomponent fibers, commercially available from BASF
Corporation, and have an overall basis weight of from about 50 to
about 120 gsm.
The bodyside liner or topsheet 104 is formed of a liquid permeable
material so that liquid waste, and possibly semi-solid waste as
well, can pass through the liner and be absorbed by the absorbent
assembly 106. Suitable bodyside liners 104 may comprise a nonwoven
web or sheet of wet strength tissue paper, an apertured film, a
spunbonded, meltblown or bonded-carded web composed of synthetic
polymer filaments or fibers, such as polypropylene, polyethylene,
polyesters or the like, or a web of natural polymer filaments or
fibers such as rayon or cotton. In addition, the bodyside liner
104 may be treated with a surfactant to aid in liquid transfer.
In one particular embodiment, the liner 104 comprises a nonwoven,
spunbond polypropylene fabric having a basis weight of about 17
gsm. The fabric is pin apertured and surface treated with a surfactant
commercially available from Union Carbide Chemicals and Plastics
Company, Inc. under the trade designation TRITON X-102. As used
herein, the term "fabric" is used to refer to all of the
woven, knitted and nonwoven fibrous webs. The term "nonwoven
web" means a web of material that is formed without the aid
of a textile weaving or knitting process.
In the illustrated embodiment, the elongated side elastic members
108 are longitudinally orientated contiguous with each side edge
134 and extend toward the end edges 132. The side elastic members
108 may be bonded in a stretched condition intermediate the moisture
barrier 102 and the bodyside liner 104 using ultrasonic bonds, adhesives,
thermal bonds, or other suitable means, in either a straight or
a curved shape. Alternatively, the side elastic members 108 may
be bonded in a relaxed state to a gathered portion of the moisture
barrier 102 the bodyside liner 104 or both. As used herein, the
terms "elastic", "elasticized" and "elasticity"
mean that property of a material by virtue of which it tends to
recover its original size and shape after removal of a force causing
a deformation.
The side elastic members 108 may be formed of a dry-spun coalesced
multifilament elastomeric thread sold under the tradename LYCRA
and available from E. I. Du Pont de Nemours and Company. Alternately,
the elastic members may be formed of other typical elastics utilized
in making incontinence products, such as a thin ribbon of natural
rubber, a stretch bonded laminate material comprising a prestretched
elastic meltblown inner layer sandwiched between and bonded to a
pair of spunbond polypropylene nonwoven webs, or the like. Elasticity
could also be imparted to the absorbent article by extruding a hot
melt elastomeric adhesive between the moisture barrier 102 and the
liner 104. Other suitable elastic gathering means are disclosed
in U.S. Pat. Nos. 4938754 to Mesek and 4388075 to Mesek et al.
The powder may desirably comprise individual molecular sieve particles
having a median particle size of less than 350 microns, particularly
less than about 200 microns, more particularly less than about 100
microns, and most particularly less than about 50 microns. In one
particular embodiment, the molecular sieve has a particle size distribution
from 1.4 to 44 microns with a median particle size of about 3.7
microns. One suitable procedure for determining the particle size
of a molecular sieve is a standard sieve analysis, although other
techniques such as optical microscopy, image analysis, optical or
resistivity zone sensing, or the like may also be appropriate depending
upon the general size of the particles. The procedure for measuring
particle size takes into consideration individual molecular sieve
particles or agglomerates of such particles.
Applicants have discovered that improved handling and distribution
of molecular sieve particles is possible when the moisture content
is controlled to relatively high levels. By controlling the moisture
content of the molecular sieve particles to the indicated levels,
the powder becomes conductive and thus discharges most of its static
charge. This can be visually observed by a reduction in the occurrence
of sparks that would otherwise be present, and by less movement
of the particles as a consequence of objects, such as a person's
hand, moving in close proximity to the particles. The reduced static
levels diminish the propensity of the molecular sieve particles
to form clusters and limit the integrity of the clusters to levels
at which separation, for example by mechanical means, is economically
feasible. More specifically, the powder can be separated into a
finer and more uniform final particulate. This improved molecular
sieve distribution permits a cost effective utilization of the odor
control material because the finer distribution provides better
odor adsorption performance. From a processing standpoint, the reduced
levels of static also lessen airborne contamination, referred to
as dusting; decrease buildup of the material on working surfaces;
and permit easier removal of any such buildups by airjets or vacuum.
In one embodiment, the method for distributing a molecular sieve
powder 30 may be carried out using the equipment illustrated in
FIG. 2. In general, the method utilizes a metering device 32 that
receives the molecular sieve powder 30 from a source 20 (FIG. 1)
and delivers it to an extrusion device 34. The extrusion device
34 separates the powder 30 into generally uniform diameter particulate
material 36 including clusters and individual particles that are
then delivered to a vibration device 38. The vibration device 38
is operable to further separate the clusters into smaller sizes
and deliver the powder to a deposition station 26 for incorporation
into a product.
The illustrated metering device 32 comprises a volumetric feeder
including a bulk solids agitating hopper 40 a nozzle 42 and a
rotating helix (screw) 44 that extends at least partially into the
interior of the hopper 40 and transports the molecular sieve powder
30 out of the hopper through the nozzle 42. The hopper 40 desirably
comprises a liner (not shown) formed of rubber or the like and an
agitator mechanism (not shown) to shake the liner and cause the
powder 30 to drop toward the rotating helix 44. Suitable metering
devices 32 are available from AccuRate Inc. of Whitewater, Wis.,
USA, under the trademark ACCURATE. One such system is a 604 Series
volumetric feeder using dual 1/4 horsepower motors for separate
agitation speed control and a 1 inch square stock helix having a
spiral that is open in the center to prevent powder buildup on the
center shaft.
For applications involving absorbent articles, the metering device
32 may for example supply the molecular sieve powder 30 at a feedrate
of at least 50 grams per minute, such as about 55 grams per minute.
Alternative metering devices such as a weight loss feeder, a flatstock
helix, an auger, or the like may also be used.
The extrusion device 34 comprises a screening mechanism such as
1/16 inch mesh rectangular screen (1.59 mm). Selection of a screen
size should consider the desired particle size exiting the screen
in combination with the metering device power and desired system
throughput. This screen desirably provides a generally uniform diameter
powder particulate size. Upon exiting the extrusion device 34 the
particulate material 36 desirably has a generally uniform average
diameter of less than about 1500 microns, and particularly less
than about 1100 microns, for improved performance. It may be beneficial
to intentionally agglomerate the molecular sieve particles into
generally uniform diameter clusters by extrusion or other means
in order to improve the overall uniformity and distribution of clusters
at the deposition station 26.
Other mechanisms such as a sifter or the like may alternatively
be used to refine the molecular sieve powder 30 into appropriately
sized particulate material 36. From the screen, the clusters and
individual particles 36 fall by gravity or are transported by other
suitable means to the vibration device 38.
In the illustrated embodiment, the vibration device 36 comprises
a vibrating horn 50 a basket 52 disposed on the vibrating horn
50 and a funnel 54 to direct particulate material 36 exiting the
vibrating horn 50. The vibrating horn 50 has opposite entry and
exit ends 56 and 58 between which particulate material 36 travels
prior to exiting through the optional funnel 54. In the illustrated
embodiment, the vibrating horn 50 narrows from about 3 inches (7.6
cm) at the entry end 56 to about 1.5 inch (3.8 cm) at the entrance
to the funnel 54. The hopper 40 and the vibrating horn 50 are both
mounted on a frame 63 which is connected to a fixed structural support
(not shown). The funnel 54 is used to control the direction of the
particulate material 36.
The basket 52 is mounted at the entry end 56 of the vibrating horn
50 so that particulate material 36 exiting the extrusion device
34 is deposited in the basket 52. The basket 52 is desirably formed
of a perforated material such as metal or the like. The basket 52
functions to accumulate particulate material 36 and eliminate surges
of material; widen the distribution pattern of the particulate material
36; and sift the particulate material 36 through the perforations
onto the vibrating horn 50 to evenly distribute the particulate
material 36 across the width of the basket 52.
The vibrating horn 50 comprises an actuator 60 that is operably
connected to a power source (not shown) and adapted to vibrate the
horn 50. One suitable actuator 60 is a 20 watt vibrator operating
at 3600 cycles per minute. The design of the horn 50 and the operating
characteristics of the actuator 60 are selected so that the particulate
material 36 is transported through the basket 52 and to the exit
end 58 of the vibrating horn 50.
At the deposition station 26 the particulate material 36 exits
the funnel 54 and is deposited onto a substantially continuous moving
carrier substrate 70. In an alternative embodiment, the particulate
material 36 at the deposition station 26 is deposited onto a substantially
continuous moving carrier, including but not limited to machinery
such as screens, belts, and vibrating horns. Optionally, an adhesive
72 is deposited onto the carrier substrate 70 by an adhesive die
head 74 either prior to or after placement of the particulate material
36 on the carrier substrate. Also optionally, a substantially continuous,
moving cover substrate 76 may be married with the carrier substrate
70 at nip rolls 78 rotating in the direction of arrows 79 to sandwich
the particulate material 36 between the carrier and cover substrates.
The carrier and cover substrates 70 and 76 suitably comprise gas
permeable materials such as nonwovens or apertured films. In one
particular embodiment the substrates 70 and 76 comprise cellulosic
tissue wraps each having a basis weight of 26 grams per square meter
(gsm).
The adhesive 72 functions to bond the particulate material 36 and
the cover substrate 76 to the carrier substrate 70 thus forming
a composite 80 moving in the direction of arrow 82. The adhesive
72 is desirably applied in a meltspray application that bonds the
molecular sieve particles in place but does not block volatile materials
from reaching the crystalline structure of the molecular sieve.
One suitable adhesive die unit for dispensing the adhesive is available
from J and M Laboratories, Inc. of Dawsonville, Ga., USA, and is
identified as a MAMBI DURAFIBER die, Model DF-12-16. The particular
adhesive 72 is desirably a hot melt adhesive that does not significantly
contaminate the efficacy of the molecular sieve. Suitable adhesives
are available from Ato Findley Adhesives from Wauwatosa, Wis., USA,
under the trade designation H-2088 or National Starch and Chemical
Corporation of Bridgewater, N.J., USA, under the trade designation
34-5610.
In particular embodiments, the carrier and cover substrates 70
and 76 may be transported at speeds of over 300 feet per minute
(fpm), for example about 333 fpm. Further, the resultant composite
80 may include molecular sieve add-on levels of about 0.1 to about
50 gsm with hot melt adhesive add-on levels of about 3 to about
10 gsm. More particularly, the molecular sieve add-on level may
range between about 4 to about 50 gsm. Suitable adhesion of the
molecular sieve to the substrates and the substrates to one another
is believed possible at about 3 to about 5 gsm melt spray add-ons.
The wide ranges of molecular sieve and adhesive add-ons yield a
large matrix of odor controlling material composites 80 that are
capable of being incorporated into personal care absorbent articles
or other products.
Alternative refining equipment is illustrated in FIG. 3. Similar
to the equipment of FIG. 2 the molecular sieve powder 30 is processed
through a metering device 32 (not shown) having a nozzle 42 and
a rotating helix 44. Rather than the extrusion device 34 and vibrating
horn 50 though, in this embodiment refining is accomplished by
vibrating the nozzle 42 and causing the particulate material 36
(not shown) to be distributed through a slot 68 in the nozzle. In
particular, a vibration device 66 is operably connected to a power
source (not shown) and adapted to vibrate the nozzle 42. The size
of the slot 68 may be selected to provide the desired spreading
pattern, and may be adjustable. In one particular embodiment, the
slot 68 has a length of about 1.5 inches (3.81 cm) and a height
of 0.375 inch (0.95 cm). The particulate material 36 exiting the
slot 68 desirably have mean diameters of the same magnitude as referenced
above in relation to the extrusion device of FIG. 2.
By way of illustration, one exemplary absorbent article utilizing
a molecular sieve composite 80 is illustrated by an incontinence
pad 100 in FIGS. 4 and 5. The pad 100 includes a moisture barrier
102 a bodyside liner 104 a retention portion in the form of an
absorbent assembly 106 disposed between the moisture barrier and
bodyside liner, and a molecular sieve composite 80 disposed between
the absorbent assembly 106 and the bodyside liner 104. Desirably
although not necessarily, the pad 100 may also include side elastic
members 108 and a liquid acquisition/distribution layer 110. The
pad 100 desirably further comprises a means for holding the pad
100 in position during use (not shown). For example, the pad 100
may comprise a garment attachment adhesive, a body attachment adhesive,
belts, straps, wings, mechanical fasteners, and/or other suitable
fastening devices to secure the pad in position to absorb body exudates.
With particular reference to FIG. 4 the illustrated pad 100 defines
a longitudinal axis or center line represented by arrow 130 which
generally corresponds to the greatest planar dimension of the product.
The pad 100 has opposite, longitudinal end edges 132 and opposite,
longitudinal side edges 134 that extend between the longitudinal
end edges. The longitudinal side edges 134 are shown as generally
straight, but optionally, may be curvilinear and contoured, for
example so that the pad 100 is generally hourglass shaped.
The moisture barrier 102 and bodyside liner 104 are desirably longer
and wider than the absorbent assembly 106 and the composite 80 so
that the peripheries of the moisture barrier 102 and bodyside liner
104 may be bonded together using ultrasonic bonds, thermal bonds,
adhesives, or other suitable means. Additionally, the absorbent
assembly 106 and the composite 80 may be bonded directly to the
moisture barrier 102 and the bodyside liner 104 using ultrasonic
bonds, thermal bonds, adhesives, or other suitable means. As used
herein, the term "bonded" refers to the joining, adhering,
connecting, attaching, or the like, of two elements. Two elements
will be considered to be bonded together when they are bonded directly
to one another or indirectly to one another, such as when each is
directly bonded to intermediate elements.
The moisture barrier or backsheet 102 desirably comprises a material
that is formed or treated to be liquid impermeable. Alternatively,
the moisture barrier 102 may comprise a liquid permeable material
and other suitable means may be provided to impede liquid movement
away from the absorbent assembly 106 such as a liquid impermeable
layer (not shown) associated with the absorbent assembly. The moisture
barrier 102 may also be gas permeable over either all or part of
its surface area.
The moisture barrier 102 may comprise a single layer of material
or a laminate of two or more separate layers of material. Suitable
moisture barrier materials include films, wovens, nonwovens, laminates
of films, wovens, and/or nonwovens, or the like. For example, the
moisture barrier 102 may comprise a thin, substantially liquid impermeable
web or sheet of plastic film such as polyethylene, polypropylene,
polyvinyl chloride or similar material. The moisture barrier material
may be transparent or opaque and have an embossed or matte surface.
One particular material for the moisture barrier 102 is a polyethylene
film that has a nominal thickness of about 0.028 millimeter and
a systematic matte embossed pattern, and that has been corona treated
on both sides.
The absorbent assembly 106 comprises materials adapted to absorb,
distribute, and retain liquid waste, and may be in the form of a
single or multi-layered structure. The absorbent assembly 106 may
comprise various absorbent materials, such as an air-formed batt
of cellulosic fibers (i.e., wood pulp fluff) or a coform material
composed of a mixture of cellulosic fibers and synthetic polymer
fibers. The absorbent assembly 106 may include 0-95 weight percent
of organic or inorganic high-absorbency materials to increase the
absorbency of the assembly. As used herein, the term "high-absorbency
materials" refers to materials that are capable of absorbing
at least about 15 and desirably more than 25 times their weight
in water. Suitable high-absorbency materials are described in U.S.
Pat. Nos. 4699823 issued Oct. 13 1987 to Kellenberger et al.
and 5147343 issued Sep. 15 1992 to Kellenberger, which are incorporated
herein by reference. High-absorbency materials are available from
various commercial vendors, such as The Dow Chemical Company; Hoechst
Celanese Corporation; Chemische Fabrik Stockhausen, GMBH; and Allied
Colloids, Inc.
The molecular sieve composite 80 is shown in particularly large
scale in order to illustrate the presence of the molecular sieve
particulate material 36. The composite 80 may be cut or trimmed
as needed along with the absorbent assembly 106 for example to
provide the hourglass shaped structure as illustrated in FIGS. 4
and 5. Alternatively, the composite 80 may be sized to reside within
the pad 100 without being trimmed during assembly of the pad 100.
The acquisition/distribution layer 110 is desirably provided to
help decelerate and diffuse surges of liquid that may be introduced
into the absorbent assembly 106. The acquisition/distribution layer
110 may be positioned subjacent the bodyside liner 104 as illustrated,
or alternatively disposed on the inwardly facing, bodyside surface
of bodyside liner. Suitable configurations of the acquisition/distribution
layer 110 are described in U.S. Pat. No. 5192606 issued Mar. 9
1993 to D. Proxmire et al.; U.S. Pat. No. 5486166 issued Jan.
23 1996 to Ellis et al.; U.S. Pat. No. 5490846 issued Feb. 13
1996 to Ellis et al.; and U.S. patent application Ser. No. 096654
of W. Hanson et al., titled "Thin Absorbent Article Having
Rapid Uptake Of Liquid," and filed Jul. 22 1993 now U.S. Pat.
No. 5509915; the disclosures of which are hereby incorporated
by reference. By way of illustration, the acquisition/distribution
layer 110 may comprise a through-air bonded carded web composed
of a blend of 40% of 6 denier polyester fibers, commercially available
from Hoechst Celanese Corporation, and 60% of 3 denier polypropylene/polyethylene
side-by-side bicomponent fibers, commercially available from BASF
Corporation, and have an overall basis weight of from about 50 to
about 120 gsm.
The bodyside liner or topsheet 104 is formed of a liquid permeable
material so that liquid waste, and possibly semi-solid waste as
well, can pass through the liner and be absorbed by the absorbent
assembly 106. Suitable bodyside liners 104 may comprise a nonwoven
web or sheet of wet strength tissue paper, an apertured film, a
spunbonded, meltblown or bonded-carded web composed of synthetic
polymer filaments or fibers, such as polypropylene, polyethylene,
polyesters or the like, or a web of natural polymer filaments or
fibers such as rayon or cotton. In addition, the bodyside liner
104 may be treated with a surfactant to aid in liquid transfer.
In one particular embodiment, the liner 104 comprises a nonwoven,
spunbond polypropylene fabric having a basis weight of about 17
gsm. The fabric is pin apertured and surface treated with a surfactant
commercially available from Union Carbide Chemicals and Plastics
Company, Inc. under the trade designation TRITON X-102. As used
herein, the term "fabric" is used to refer to all of the
woven, knitted and nonwoven fibrous webs. The term "nonwoven
web" means a web of material that is formed without the aid
of a textile weaving or knitting process.
In the illustrated embodiment, the elongated side elastic members
108 are longitudinally orientated contiguous with each side edge
134 and extend toward the end edges 132. The side elastic members
108 may be bonded in a stretched condition intermediate the moisture
barrier 102 and the bodyside liner 104 using ultrasonic bonds, adhesives,
thermal bonds, or other suitable means, in either a straight or
a curved shape. Alternatively, the side elastic members 108 may
be bonded in a relaxed state to a gathered portion of the moisture
barrier 102 the bodyside liner 104 or both. As used herein, the
terms "elastic", "elasticized" and "elasticity"
mean that property of a material by virtue of which it tends to
recover its original size and shape after removal of a force causing
a deformation.
The side elastic members 108 may be formed of a dry-spun coalesced
multifilament elastomeric thread sold under the tradename LYCRA
and available from E. I. Du Pont de Nemours and Company. Alternately,
the elastic members may be formed of other typical elastics utilized
in making incontinence products, such as a thin ribbon of natural
rubber, a stretch bonded laminate material comprising a prestretched
elastic meltblown inner layer sandwiched between and bonded to a
pair of spunbond polypropylene nonwoven webs, or the like. Elasticity
could also be imparted to the absorbent article by extruding a hot
melt elastomeric adhesive between the moisture barrier 102 and the
liner 104. Other suitable elastic gathering means are disclosed
in U.S. Pat. Nos. 4938754 to Mesek and 4388075 to Mesek et al.
The foregoing detailed description has been for the purpose of
illustration. Thus, a number of modifications and changes may be
made without departing from the spirit of the scope of the present
invention. For instance, alternative or optional features described
as part of one embodiment can be used to yield another embodiment.
Additionally, two named components could represent portions of the
same structure. Therefore, the invention should not be limited by
the specific embodiments described, but only by the claims. |