U.S. patent application number 10/238431 was filed with the patent office on 2003-01-09 for method of stabilizing composite media and media produced thereby.
Invention is credited to Koslow, Evan E..
Application Number | 20030008117 10/238431 |
Document ID | / |
Family ID | 24315983 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030008117 |
Kind Code |
A1 |
Koslow, Evan E. |
January 9, 2003 |
Method of stabilizing composite media and media produced
thereby
Abstract
There is provided composite media and a method of producing
them. The composite media contain a coalesced composite mixture of
particles of an active ingredient and binder particles. The binder
particles preferably also fuse the composite structure to front and
back substrates. The composite media also have stabilizing
particles that fuse with both the particles of an active ingredient
and the substrates, thereby forming a composite medium according to
the present invention.
Inventors: |
Koslow, Evan E.; (Weston,
CT) |
Correspondence
Address: |
SHIRLEY S. MA
KX INDUSTRIES, L.P.
269 S. LAMBERT ROAD
ORANGE
CT
06477
US
|
Family ID: |
24315983 |
Appl. No.: |
10/238431 |
Filed: |
September 9, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10238431 |
Sep 9, 2002 |
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09579205 |
May 26, 2000 |
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09579205 |
May 26, 2000 |
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08903395 |
Jul 22, 1997 |
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6077588 |
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08903395 |
Jul 22, 1997 |
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08813055 |
Mar 7, 1997 |
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5792513 |
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Current U.S.
Class: |
428/198 |
Current CPC
Class: |
B01J 20/28035 20130101;
Y10T 428/258 20150115; B01J 20/2803 20130101; B05D 1/28 20130101;
B32B 5/16 20130101; B32B 2305/30 20130101; D06N 3/045 20130101;
D06N 3/0056 20130101; D21H 19/58 20130101; D06N 3/0093 20130101;
B05D 3/12 20130101; A61F 13/532 20130101; B01J 20/28016 20130101;
Y10T 428/256 20150115; B05D 5/06 20130101; Y10T 428/259 20150115;
D21H 23/64 20130101; D21H 21/14 20130101; B32B 37/04 20130101; Y10T
428/24942 20150115; D06N 3/0063 20130101; A61F 13/15658 20130101;
Y10T 428/254 20150115; A61F 2013/530547 20130101; A61F 2013/530554
20130101; B32B 5/30 20130101; A61F 13/8405 20130101; Y10T 428/24826
20150115; B32B 37/24 20130101; Y10T 428/257 20150115; B32B 27/12
20130101; D21H 25/06 20130101; A61F 2013/8408 20130101; B01J
20/28004 20130101; B01J 20/28033 20130101; A61F 2013/530489
20130101; B05D 1/30 20130101; B32B 2305/20 20130101 |
Class at
Publication: |
428/198 |
International
Class: |
B32B 027/14 |
Claims
What is claimed is:
1. A composite medium comprising: a backing sheet; a covering
sheet; and a layer disposed between said backing sheet and said
covering sheet, said layer having particles of an active
ingredient, binder particles and stabilizing particles, wherein
said active particles are coalesced by said binder particles, and
wherein each of said stabilizing particles forms a bond with both
said backing sheet and said covering sheet.
2. The composite medium of claim 1, wherein said backing sheet is
an impermeable material.
3. The composite medium of claim 1, wherein said backing sheet is a
permeable material.
4. The composite medium of claim 1, wherein said covering sheet is
a permeable material.
5. The composite medium of claim 1, wherein said composite layer
has an average thickness of about 0.2 mm to 5 mm.
6. The composite medium of claim 1, wherein said particles of an
active ingredient are formed from at least one component selected
from the group consisting one of: adsorbent particles, absorbent
particles, particles that release liquid or gases held therein, and
mixtures thereof.
7. The composite medium of claim 1, wherein said particles of an
active ingredient are formed from at least one component selected
from the group consisting one of: iodinated resin, activated
carbon, activated alumina, alumina-silicates, ion-exchange resins,
manganese oxides, iron oxides, zeolites, hydrophilic polymeric
materials, and mixtures thereof.
8. The composite medium of claim 1, wherein said particles of an
active ingredient have an average particle size of between about 5
microns to 5000 microns.
9. The composite medium of claim 1, wherein said binder particles
are formed from at least one component selected from the group
consisting one of thermoplastic materials, thermoset materials, and
combinations thereof.
10. The composite medium of claim 1, wherein said binder particles
are formed from at least one component selected from the group
consisting of: polypropylene, linear low-density polyethylene, low
density polyethylene, ethylene-vinyl acetate copolymer, polyolefin,
phenol-formaldehyde resin, melamine resin, and mixtures
thereof.
11. The composite medium of claim 1, wherein said binder particles
have an average particle size of between about 5 microns to 50
microns.
12. The composite medium of claim 1, wherein said stabilizing
particles are formed from at least one component selected from the
group consisting of thermoplastic materials, thermoset materials,
and combinations thereof.
13. The composite medium of claim 1, wherein said stabilizing
particles are formed from at least one component selected from the
group consisting of polypropylene, linear low-density polyethylene,
low density polyethylene, ethylene-vinyl acetate copolymer,
polyolefin, phenol-formaldehyde resin, melamine resin, and mixtures
thereof.
Description
[0001] This application is a continuation-in-part of co-pending
U.S. patent application Ser. No. 08/903,395, filed Jul. 22, 1997,
which is a division of U.S. patent application Ser. No. 08/8
13,055, filed Mar. 7, 1997 (issued as U.S. Pat. No. 5,792,513).
FIELD OF THE INVENTION
[0002] The present invention relates generally to activated media.
More particularly, the present invention relates to a method of
stabilizing activated media and media produced thereby.
BACKGROUND OF THE INVENTION
[0003] It is often desirable to impregnate, cover, or otherwise
treat a base material with an active or activated material, such as
an absorbent or adsorbent material. One example would be a
non-woven medium coated with agents having fluid adsorption and/or
odor adsorption characteristics, as found in children's diapers,
adult incontinence products, feminine hygiene products, and other
adsorbent articles of clothing. Other examples include coated paper
tissues and toweling, as well as surgical bandages and sanitary
napkins. Other materials may be used as adsorbent materials, such
as cyclodextrins or zeolites for odor control, or other adsorbents
such as silicates, aluminas, or activated carbons.
[0004] The active, i.e., adsorbent, materials used to coat a base
material may be fibrous or particulate materials. However, certain
materials known in the art (e.g., fluff pulp fibers) have limited
adsorption capacity, and hence perform disappointingly during
normal wear. In addition, products containing such materials are
often heavy and/or bulky. Thus, it is preferable to use at least
some portion of particles composed of super adsorbent polymers
(SAP).
[0005] Yet, it is difficult to immobilize powdered or small
granular particles of SAP. Historically, microscopic active
materials were immobilized on foams or on surfaces coated with a
thin layer of pressure-sensitive adhesive. U.S. Pat. No. 5,462,538
to Korpman is an example of a method of immobilizing adsorbent
material on a surface coated with a thin layer of
pressure-sensitive adhesive. Using this method may produce large
gaps between individual microscopic adsorbent elements. Also, the
resulting adsorbent core has only a single layer of adsorbent
material. PCT Publication No. WO 94/01069 to Palumbo is another
example of a method of immobilizing particulate adsorbent material.
However, the adsorbent particles are not bonded to the substrates.
Moreover, the adsorbent particles are not in significant contact
with the binder particles. Thus, neither method effectively
restrains powdered or small granular particles of an active
ingredient.
[0006] As a more effective alternative, U.S. Pat. No. 5,792,513,
which is fully incorporated herein by reference, discloses a
product formed from a composite mixture of adsorbent particles and
binder particles fused to a substrate. While this product provides
excellent absorption characteristics, the particles swell when
exposed to fluid and then separate from the substrate and each
other during normal use. This loose material is then free to slump
or move.
[0007] In light of the foregoing, there remains a need for media,
and a method of producing such media, in which the particles of an
active ingredient are substantially immobilized even after they
have become swollen, while maintaining excellent composite
integrity.
SUMMARY OF THE INVENTION
[0008] The present invention provides an improved composite medium,
in which the particles of an active ingredient are substantially
immobilized. A further object is to provide absorbent or adsorbent
articles having stabilizing particles dispersed throughout a
coalesced composite layer of particles of an active ingredient and
binder particles. By substantially immobilizing the particles of an
active ingredient the present invention effectively prevents
migration of the particles of an active ingredient, thereby
creating an adsorbent product with enhanced integrity throughout
the use cycle of the product.
[0009] Accordingly, the present invention provides composite media
and a method of producing them. The composite media contain a
coalesced composite mixture of particles of an active ingredient
and binder particles. The binder particles preferably also fuse the
composite structure to front and back substrates. The composite
media also have stabilizing particles that fuse with both the
particles of the active ingredient and the substrates, thereby
forming a composite medium according to the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side plan-view of the composite media of the
present invention; and
[0011] FIG. 2 is a schematic diagram illustrating an apparatus for
the practice of the method of this invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] Referring to the drawings and, in particular, FIG. 1, there
is provided a composite medium generally indicated as 1. Composite
medium 1 has a backing substrate 10 and a covering substrate
20.
[0013] Backing substrate 10 and covering substrate 20 may be formed
of various materials depending upon the application. By way of
example, substrates 10, 20 may be a permeable material, such as a
non-woven fibrous material, e.g., spun-bonded polyester or
polyolefin. Woven substrates may also be used. Furthermore,
substrates 10, 20 may optionally be formed using cellulosic
materials, such as paper, or a combination of cellulosic and
thermoplastic fibers. Either substrate 10 or 20 may also be an
impermeable material, such as a plastic film (e.g., Mylar(.RTM.)),
a permeable backsheet or membrane or another suitable material.
[0014] The particular material selected for substrates 10, 20 can
also effect the kinetics of adsorption of composite medium 1. For
example, substrates 10, 20 can modify the mean pore size and the
overall porosity, provide supplemental adsorption, improve tensile
strength, flexibility, and pleatability, and effect wicking and
fluid distribution.
[0015] Between substrates 10, 20, there is a layer, generally
indicated as 2. Layer 2 has particles of an active ingredient 30,
binder particles 40, and stabilizing particles 50. Particles of an
active ingredient 30 are coalesced or fused together by binder
particles 40. An amount of binder particles 40 may also be fused to
points on either substrates 10 or 20, thereby also binding
particles 30 to substrates 10 and 20. However, binding particles 40
will only be fused with one of substrates 10 and 20, rather than
both. Stabilizing particles 50 may also be bonded to particles of
an active ingredient 30 and, in contrast to binding particles 40,
are fused to both backing substrate 10 and covering substrate 20,
thereby forming a stabilizing bond or quilting effect.
[0016] The thickness of layer 2 will vary depending on a variety of
factors, including the size of the particles 30, 40, and 50, the
quantity of particles 30, 40, and 50, the degree of coalescence
between particles 30, 40, and 50, and whether other particles or
fibers, such as fluff pulp, are used in layer 2. Preferably, the
thickness of layer 2 is about 0.2 mm to about 5 mm.
[0017] Particles of an active ingredient 30 can potentially be
formed of any material. For example, particles of an active
ingredient 30 may absorb or adsorb fluids or gases. Furthermore,
particles of an active ingredient 30 may be used to release fluids
or gases held therein, for example, to deliver fluids, such as
medicaments. Materials such as iodinated resin, activated carbon,
activated alumina, aluminum powders, nickel powders,
alumina-silicates, ferromagnetic materials, ion-exchange resins,
manganese or iron oxides, zeolites, glass beads, ceramics,
diatomaceous earth, and cellulosic materials can also be used as
particles of an active ingredient 30. In addition, particles of an
active ingredient 30 may also be polymeric materials, such as SAP.
The cross sectional size of particles of an active ingredient 30 is
preferably within a range of about 5 microns to about 5000
microns.
[0018] Materials forming binder particles 40 may potentially
include any material known in the art. In particular, thermoplastic
and thermoset materials are useful for the practice of the present
invention. For example, binder particles 40 may be polyethers,
polyolefins, polyvinyls, polyvinyl esters, polyvinyl ethers,
ethylene-vinyl acetate copolymers, or a mixture thereof. Also,
suitable binder particles may be produced from particulate
thermoset resins known in the art, such as phenol-formaldehyde or
melamine resins, with or without additional crosslinking agents.
Preferably, binder particles 40 are present in such an amount and
at such a size that they do not substantively interfere with the
functioning of particles 30. Binder particles 40 are preferably
about 5 microns to about 50 microns in size.
[0019] The critical feature of this invention resides in
stabilizing particles 50 that are used to form through-web
stabilizing bonds within layer 2. First, stabilizing particles 50
perform a similar function as binder particles 40, specifically
coalescing or fusing together particles of an active ingredient 30.
However, they are extremely limited in their capacity to stabilize
the active ingredient particles because they are large and provide
limited surface area to interface with the active ingredient and
they are generally present in small amounts, again limiting their
ability to stabilze other particles. Stabilizing particles 50 are
also adhered or fused to both substrates 10, 20 because they are
selected to have a particle size roughly equal to or greater than
the thickness of layer 2. Materials forming stabilizing particles
50 are potentially any suitable material, such as the materials
listed in reference to binding particles 40, e.g., a thermoplastic
or a thermoset material. Stabilizing particles 50 are preferably
present in such an amount and at such a size that they do not
substantively interfere with the functioning of particles of an
active ingredient 30 and binder particles 40. It is preferred that
stabilizing particles 50 be both larger in size and fewer in number
compared to binder particles 40. Preferably, stabilizing particles
50 are equal to or larger than the thickness of layer 2, so as to
allow stabilizing particles 50 to span the entire thickness of
layer 2 and directly adhere to substrates 10, 20. However,
stabilizing particles may be smaller than the thickness of layer 2,
for instance, if a ribbed effect for composite medium 1 is desired.
In addition, stabilizing particles may be intimately grouped
together, thereby binding to both substrates 10, 20 in the
aggregate.
[0020] FIG. 2 illustrates an exemplary apparatus for the practice
of this invention. A supply roll 100 provides a substrate 120 to be
treated, such as a nonwoven tissue or toweling paper. Downstream
from supply roll 100 is a knurled roller 130 positioned to receive
a mixture of particles of an active ingredient 30, binder particles
40, and stabilizing particles 50, the mixture generally being
indicated as 140 and dispensed from a hopper 160. Mixture 140 is
applied to the upper surface of substrate 120 as a continuous
coating or, alternatively, as a coating of a specific design such
as, for example, stripes. A brush 180 may be employed to aid in
removing mixture 140 from knurled roller 130. Thereafter, substrate
120 is passed through a nip 200 between a heated idler roller 220
and a drive roller 240. Alternatively, before being passed through
nip 200, substrate 120 may also be preheated, for example, by a
convection or infrared oven. A pneumatic cylinder is connected via
a rod 280 to the axle of idler roller 220 to maintain a desired
pressure on substrate 120 within nip 200. In passing over the
surface of heated roller 220, mixture 140 is heated to a
temperature equal to or greater than the softening temperature of
binder particles 40 and stabilizing particles 50, but lower than
the softening temperature of particles of an active ingredient 30.
Within nip 200, binder particles 40 and stabilizing particles 50
fuse under pressure with particles of an active ingredient 30,
while stabilizing particles 50 also fuse with substrate 120. An
amount of binder particles 40 may fuse with substrate 120.
Furthermore, in a preferred alternative to the above described
apparatus, a second supply roll 300 of a substrate 320, which may
be of the same or a different material from that of substrate 120,
is also passed between nip 200 on the top of mixture 140.
Stabilizing particles 50 fuse with substrate 320 and an amount of
binder particles 40 may also fuse with substrate 320. However,
while stabilizing particles 50 fuse with both substrate 120 and
320, binder particles 40 will only fuse with either substrate 120
or 320. Upon leaving the nip 200, binder particles 40 and
stabilizing particles 50 cool and harden. The composite medium 240
passes onto a takeup roll 360.
[0021] Coalescing particles of an active ingredient 30 with
interposed binder particles 40 and stabilizing particles 50 results
in more complete coverage of the backing substrate 10 and places
particles of an active ingredient 30 in closer proximity to each
other. In addition, it is possible to vary the depth and porosity
of layer 2 and to have multiple layers of active ingredient fully
stabilized by binder particles 40. When composite layer 1 contains
SAP and is wetted, the SAP particles swell and generally break
their bonds with binder particles 40 and any bonds that might exist
with stabilizing particles 50. However, the bonds between
substrates 10 and 20 and stabilizing particles 50 are retained and
prevent the wholesale disassembly of composite layer 1. These
stable bonds do not prevent local swelling of the composite layer
1, but do provide localized stabilization of composite layer 1 at
each point where stabilizing particle 50 spans composite layer 1.
These bonds provide a random quilting effect that prevents the
movement of the swollen SAP mass.
[0022] Although composite medium 1, and the method of producing
such a medium, has been described with respect to one or more
particular embodiments, it will be understood that other
embodiments of the present invention may be employed without
departing from the spirit and scope of the present invention.
Hence, the present invention is deemed limited only by the appended
claims and the reasonable interpretation thereof.
* * * * *