U.S. patent application number 17/097868 was filed with the patent office on 2021-06-24 for fibers with absorbent particles adhered thereto, methods for their production and articles thereof.
The applicant listed for this patent is North Carolina State University. Invention is credited to Pierre Grondin, Benoit Maze, Behnam Pourdeyhimi.
Application Number | 20210189620 17/097868 |
Document ID | / |
Family ID | 1000005494444 |
Filed Date | 2021-06-24 |
United States Patent
Application |
20210189620 |
Kind Code |
A1 |
Pourdeyhimi; Behnam ; et
al. |
June 24, 2021 |
FIBERS WITH ABSORBENT PARTICLES ADHERED THERETO, METHODS FOR THEIR
PRODUCTION AND ARTICLES THEREOF
Abstract
Composites where nonwoven fabrics having multicomponent
synthetic fibers with adhered particles thereon are disclosed. The
multicomponent fibers have at least one polymer component with a
melting point below that of the other components, and the average
apparent particle diameter is less than the average apparent fiber
diameter. Methods of making the disclosed composites are also
disclosed.
Inventors: |
Pourdeyhimi; Behnam;
(Raleigh, NC) ; Grondin; Pierre; (Raleigh, NC)
; Maze; Benoit; (Raleigh, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
North Carolina State University |
Raleigh |
NC |
US |
|
|
Family ID: |
1000005494444 |
Appl. No.: |
17/097868 |
Filed: |
November 13, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62936067 |
Nov 15, 2019 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D04H 1/541 20130101;
D04H 3/005 20130101 |
International
Class: |
D04H 1/541 20060101
D04H001/541; D04H 3/005 20060101 D04H003/005 |
Goverment Interests
ACKNOWLEDGMENT OF GOVERNMENT FUNDING
[0002] This invention was made with government support under grant
number FA8750-14-D-0003 awarded by the U.S. Air Force Research
Laboratory. The government has certain rights in the invention.
Claims
1. A composite, comprising: multicomponent synthetic fibers,
wherein the fibers comprise at least one exposed polymer and
particles adhered to the exposed polymer, wherein that exposed
polymer has a lower melting point than other components of the
multicomponent fibers and, wherein at least about 66% of the
adhered particles have an apparent diameter that is less than the
average apparent diameter of the multi-component fibers.
2. The composite of claim 1, wherein at least about 75% of the
particles have adhered to the surface of only one of the
multicomponent fibers.
3. The composite of claim 1, wherein the adhered particles are at
least about 10 wt. % of the composite weight.
4. The composite of claim 1, wherein the adhered particles are at
least about 20 wt. % of the composite.
5. The composite of claim 1, wherein the exposed polymer has a
melting point at least about 20.degree. C. lower than other
constituents of the multicomponent fibers.
6. The composite of claim 1, where the particles are metal organic
frameworks.
7. The composite of claim 1, where the multicomponent fibers are
sheath:core, or island-in-the-sea, side-by-side, segmented pie, or
tipped trilobal type fibers.
8. The composite of claim 1, wherein at least about 75% of the
adhered particles have an apparent diameter that is less than the
average apparent diameter of the multicomponent fibers.
9. The composite of claim 1, wherein at least about 90% of the
adhered particles have an apparent diameter that is less than the
average apparent diameter of the fibers.
10. The composite of claim 1, wherein the adhered particles have an
average apparent diameter that is about 75% smaller than the
average apparent diameter of the fibers.
11. The composite of claim 1, wherein the adhered particles have an
average apparent diameter that is about 50% smaller than the
average apparent diameter of the fibers.
12. The composite of claim 1, wherein the adhered particles have an
average apparent diameter that is about 25% smaller than the
average apparent diameter of the fibers.
13. The composite of claim 1, wherein the multicomponent fibers are
in a nonwoven fabric.
14. The composite of claim 13, wherein the nonwoven fabric is a
spunbond, carded web, airlaid web, or wetlaid web.
15. The composite of claim 14, wherein the nonwoven fabric is
bonded by thermal point bonding or thru-air thermal bonding,
needled entangled, hydro-entangled.
16. The composite of claim 14, wherein the nonwoven fabric has a
web porosity above about 90%.
17. A method of forming a composite, comprising: a. heating
multicomponent synthetic fibers, wherein the fibers comprise at
least one exposed polymer having a lower melting point that other
components of the multicomponent fibers, to a temperature where the
at least one exposed polymer is molten; b. contacting the heated
multicomponent synthetic fibers with particles, such that the
particles adhere to the exposed, molten polymer; and c. cooling or
allowing to cool the fibers with particles adhered thereto. wherein
at least about 66% of the adhered particles have an apparent
diameter that is less than the average apparent diameter of the
multi-component fibers.
18. An article of clothing comprising the composite of claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to U.S.
Provisional Application No. 62/936,067, filed Nov. 15, 2019, which
is incorporated by reference herein in its entirety.
BACKGROUND
[0003] Fabrics containing particles that can absorb compounds or
microbes have many desirable uses. For example, such fabrics can be
used for air filtration or for protective clothing. Examples of
protective clothing with incorporated particles are combat uniforms
for war theaters where chemical warfare is a potential threat. Such
uniforms need to be comfortable while offering sufficient
protection; this meaning that they need to be light, drapable and
breathable while offering the mechanical properties needed for this
demanding environment in addition to inhibiting the chemical threat
from being absorbed by the skin.
[0004] Currently uniforms exist that include an outer fabric, an
inner fabric, and a core composite where a fabric is coated with a
mixture of a binder and activated carbon particles. Activated
carbon particles have limitations for this application and the use
of a binder binds a significant percentage of the particles'
surface, therefore reducing the capacity of the particles to absorb
compounds.
[0005] Fabrics containing particles that can release compounds have
also many desirable uses. For example, they can be used to release
a fragrance or health beneficial compound into a stream of air.
[0006] Methods to attach particles onto a fabric without using a
binder have been described. U.S. Pat. No. 6,024,813 describes
blending absorbent particles (e.g. activated carbon or zeolites)
with bicomponent fibers that typically have sheath:core cross
sections. In this approach, the sheaths of the bicomponent fibers
were heat activated and adhered to the outside of the particles. In
this approach, the particles were typically significantly larger
than the diameter of the fibers, resulting in significant tangling
where multiple fibers were connected together by the particle,
locking it in place. U.S. Pat. No. 5,786,059 describes a similar
approach of using sheath:core bicomponent fibers to lock larger
aerogel particles in place to form composite fabrics.
[0007] A disadvantage of these approaches is that they require
relatively large particles, therefore limiting the surface exposed
to the outside environment. This typically reduces the absorption
capacity by weight of the absorbent particles.
[0008] There is thus a need for fibers and textile composites or
fabrics that have greater absorption capacity and are breathable.
The composites, fibers, and methods disclosed herein address these
and other needs.
SUMMARY
[0009] In accordance with the purposes of the disclosed materials
and methods, as embodied and broadly described herein, the
disclosed subject matter, in one aspect, relates to compositions
and methods of using the compositions. In specific aspects, the
disclosed subject matter relates to multicomponent synthetic fibers
decorated with particles, wherein the particles are smaller than
the fiber diameter, and wherein the particles are adhered to the
fibers. Composites where nonwoven fabrics of such fibers with
adhered particles are also disclosed. In some examples, then
composites have a majority (greater than about 75%) of the
particles adhered to only one fiber are also disclosed. Further,
composites where the web porosity is at least about 90% are
disclosed. Methods of making the disclosed composites are also
disclosed.
[0010] Additional advantages will be set forth in part in the
description that follows, and in part will be obvious from the
description, or may be learned by practice of the aspects described
below. The advantages described below will be realized and attained
by means of the elements and combinations particularly pointed out
in the appended claims. It is to be understood that both the
foregoing general description and the following detailed
description are exemplary and explanatory only and are not
restrictive.
BRIEF DESCRIPTION OF THE FIGURES
[0011] The invention will be more readily understood from a reading
of the following specification and by reference to the accompanying
drawings forming a part thereof:
[0012] FIG. 1 is an example of a process to bring the hot particles
in contact with the nonwoven comprising multi-component fiber
nonwoven.
[0013] FIG. 2 is a picture taken at 500.times. of PP/PE
Island-in-the-Sea filaments with MOF particles.
[0014] FIG. 3 is a picture taken at 500.times. of CoPET/PET
Sheath:Core bicomponent fibers coated with MOF particles.
[0015] FIG. 4 is a picture taken at 250.times. of CoPET/PET
Sheath:Core bicomponent fibers coated with MOF particles.
[0016] FIG. 5 is a picture taken at 250.times. of PE/PET
Sheath:Core bicomponent fibers from highloft nonwoven coated with
MOF particles.
[0017] FIG. 6 is a picture of the system used to coat Sample 5.
[0018] FIG. 7 is a picture taken at 250.times. of PE/PET
Sheath:Core bicomponent fibers from highloft nonwoven coated with
MOF particles by processing the web in a bed of hot particles.
[0019] FIG. 8 is a picture taken at 300.times. of PE/PET
Sheath:Core bicomponent fibers from high loft nonwoven coated with
MOF particles by incorporating the particles into the nonwoven
using vibrations, then activating the sheath of the fibers by
exposure in an oven at 170.degree. C. and followed by removal of
the particles that had not adhered.
DETAILED DESCRIPTION
[0020] The present invention now will be described more fully
hereinafter with reference to the accompanying drawings, in which
some, but not all embodiments of the inventions are shown.
Preferred embodiments of the invention may be described, but this
invention may, however, be embodied in many different forms and
should not be construed as limited to the embodiments set forth
herein. Rather, these embodiments are provided so that this
disclosure will be thorough and complete, and will fully convey the
scope of the invention to those skilled in the art. The embodiments
of the invention are not to be interpreted in any way as limiting
the invention.
[0021] Many modifications and other embodiments of the invention
set forth herein will come to mind to one skilled in the art to
which this invention pertains having the benefit of the teachings
presented in the descriptions herein and the associated drawings.
Therefore, it is to be understood that the inventions are not to be
limited to the specific embodiments disclosed and that
modifications and other embodiments are intended to be included
within the scope of the appended claims.
[0022] Also, throughout this specification, various publications
are referenced. The disclosures of these publications in their
entireties are hereby incorporated by reference into this
application in order to more fully describe the state of the art to
which the disclosed matter pertains. The references disclosed are
also individually and specifically incorporated by reference herein
for the material contained in them that is discussed in the
sentence in which the reference is relied upon.
Definitions
[0023] In this specification and in the claims that follow,
reference will be made to a number of terms, which shall be defined
to have the following meanings:
[0024] Throughout the description and claims of this specification
the word "comprise" and other forms of the word, such as
"comprising" and "comprises," means including but not limited to,
and is not intended to exclude, for example, other additives,
components, integers, or steps.
[0025] As used in the description and claims, the singular forms
"a", "an", and "the" include plural referents unless the context
clearly indicates otherwise. For example, reference to "a fiber"
includes a plurality of such fibers.
[0026] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limit of that range and any other stated or intervening
value in that stated range, is encompassed. The upper and lower
limits of these smaller ranges may independently be included in the
smaller ranges, and are also encompassed, subject to any
specifically excluded limit in the stated range. Where the stated
range includes one or both of the limits, ranges excluding either
or both of those included limits are also included.
[0027] The term "fiber" herein is intended to include staple fibers
as well as continuous filaments.
[0028] As used herein, a "nonwoven fabric" means a fabric having a
structure of individual fibers or filaments that are interlaid but
not necessarily in an identifiable manner as with knitted or woven
fabrics.
[0029] As used herein, the term "adhered" is meant to describe a
close proximate association between different materials that is
primarily attributed to chemical forces, e.g., electrostatic,
hydrogen, covalent, ionic, van der Waals bonding, or physical
attachment between the materials. An adhered particle, as described
herein, is not associated with a fiber primarily because of
physical entrapment by multiple fibers, as can be visually
confirmed by microscopy, but rather by adhesive forces or physical
attachment between the particle and a single fiber.
[0030] Although specific terms are employed herein, they are used
in a generic and descriptive sense only and not for purposes of
limitation. All terms, including technical and scientific terms, as
used herein, have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs unless a
term has been otherwise defined. It will be further understood that
terms, such as those defined in commonly used dictionaries, should
be interpreted as having a meaning as commonly understood by a
person having ordinary skill in the art to which this invention
belongs. It will be further understood that terms, such as those
defined in commonly used dictionaries, should be interpreted as
having a meaning that is consistent with their meaning in the
context of the relevant art and the present disclosure. Such
commonly used terms will not be interpreted in an idealized or
overly formal sense unless the disclosure herein expressly so
defines otherwise.
Composites
[0031] Disclosed herein is a composite or nonwoven fabric that
comprises synthetic fibers with particles adhered to the fibers.
The composite can comprise multicomponent synthetic fibers, those
fibers having one or several exposed surfaces of a component that
melts at a lower temperature than other component(s) of the fibers.
The composite also comprises at least one type of active particles
having apparent diameters that are mostly smaller than the fiber
diameters, the particles being adhered to the fibers by direct
adhesion to polymer forming an exposed part or parts of the fibers
having the lower melting point. The particle is adhered to the part
of the fibers with the low melting temperature by heating the
particles above the melting point of the low melting point
component of the fibers, bringing those particles in contact with
the fabric, and subsequently cooling this fabric under the melting
point of any of its constituents. The results being a nonwoven
composite with several of the multicomponent fibers being decorated
with particles adhered to them.
[0032] FIG. 1 illustrates an exemplary method for bringing
particles into contact with a fabric, e.g., a nonwoven. Another
approach could include pre-heating the fabric prior to bringing it
in contact with the particles, preheating the particles prior to
bringing them in contact with the fabric, or pre-heating the
particles and pre-heating the fabric before bringing them in
contact with one another. Another approach could include loading
the fabric with particles, heating this composite, and then
removing the particles that have not adhered to the fiber. Further,
at any step of the process the mixture of the fabric, fibers, and
particles can be vibrated to aid distribution of the particles. In
any of these methods care should be taken to maintain the integrity
of the fibers while making a significant share of its surface tacky
or adhesive in order to capture and retain a large quantity of the
particles and achieving a good coverage.
Fibers
[0033] The fibers for use herein are synthetic multicomponent
fibers. Such fibers have two or more different polymer components
where at least one polymer is primarily exposed to the environment
(external). The multicomponent fibers can be bicomponent,
tricomponent, or have four or more components. The multicomponent
fibers can have various different configurations. For example, the
multicomponent fiber can be sheath:core (concentric sheath:core or
eccentric sheath:core), island-in-the-sea, side-by-side (50/50 or
unequal side-by-side), segmented pie, or tipped trilobal type
fiber. For the sheath:core and other configurations the cross
section is not limited to be round; options include trilobal,
ribbon-shaped, oval, and others known in the art. Generally, a
cross section that provide a higher surface by gram of fiber may be
more desirable for some applications. The multicomponent fiber
should have a significant amount of its surface comprised of a
polymer that can be heat activated to adhere to the particles.
[0034] The synthetic multicomponent fibers can be from about 5 to
about 100 microns in diameter. In certain examples, the diameter of
the multicomponent fibers is from about 5 to about 10 microns, from
about 10 to about 20 microns, from about 20 to about 50 microns,
from about 50 to about 100 microns, from about 5 to about 10
microns, from about 5 to about 20 microns, from about 5 to about 30
microns, from about 5 to about 50 microns, from about 5 to about
100 microns, from about 10 to about 30 microns, from about 30 to
about 50 microns, or from about 50 to about 100 microns. In
specific examples, the multicomponent fibers are from about 15 to
about 30 microns. The length of the multicomponent fibers need not
be limited and can be a continuous fiber or a cut or staple
fiber.
[0035] In the synthetic multicomponent fibers, at least one of the
polymer components on an exposed surface of the fiber has a melting
point that is at least 20.degree. C. lower than any other
components (polymers) of the fiber. In some examples, at least one
of the polymer components on an exposed surface of the fiber has a
melting point that is at least 30.degree. C., 40.degree. C.,
50.degree. C., or more lower than any other components (polymers)
of the fiber. In some examples, the difference between the melting
points of at least two polymers in the fiber can be 20.degree. C.
or more, e.g., a 30.degree. C., 40.degree. C., 50.degree. C. or
greater than 50.degree. C. difference. Melting point is defined
herein as the peak temperature achieved when a polymer formulation
melts as measured by differential scanning calorimetry or DSC.
[0036] In certain examples, the multicomponent fiber comprises
thermoplastic polymers. In certain examples, the polymer components
can comprise a thermoplastic polymer selected from the group
consisting of nylon 6, nylon 6/6, nylon 6/10, nylon 6/11, nylon
6/12, nylon 11, nylon 12, polyolefins such as polypropylene or
polyethylene, polyesters, polyamides, co-polyesters,
copolyetherester elastomers, polyacrylates, thermoplastic liquid
crystalline polymers, and others.
[0037] An example of suitable multicomponent fiber is the
sheath:core bicomponent fibers where the core comprises a polymer
formulation having a significantly higher melting point temperature
polymer formulation than the sheath. For example, this could be a
bicomponent fiber having a core made from polyester (PET) and a
sheath made from lower melting point co-polyester (Co-PET) or even
polyethylene. Another example would be a bicomponent fibers made
from a polypropylene core and a polyethylene sheath.
[0038] In other specific examples, the multicomponent fibers can be
an island-in-the-sea fiber having from about 2 to about 100 islands
(internal components). In certain embodiments, the multi-component
fiber can have from about 30 to about 40 islands. In other
embodiments, the multi-component fiber can have from about 2 to
about 100 islands, from about 10 to about 80 islands, from about 20
to about 60 islands, from about 30 to about 50 islands, from about
2 to about 10 islands, or from about 5 to about 30 islands. The sea
component can be the polymer that has a melting point lower than
that of the polymer used to make the islands. For example, islands
can be made from polyester (PET) and the sea can be made from lower
melting point co-polyester (Co-PET) or even polyethylene or vice
versa. Another example would be a bicomponent fibers made from a
polypropylene islands and a polyethylene sea or vice versa.
[0039] Those are not restrictive examples and many other
combinations are possible, as long as they provide an exposed part
of the fiber having a lower melting temperature that can be heat
activated than the other components of the fiber.
[0040] The multi-component fibers can form the complete nonwoven or
they can be blended with other fibers selected for their properties
(e.g. large diameter fibers to provide resilience).
Nonwovens
[0041] The nonwovens useful herein can be made by different methods
as long as they comprise multicomponent fibers as described herein.
These include spunbonds, carded webs, airlaid webs or wetlaid webs
that can be thermally bonded by point bonding or thru-air bonding,
or they can be needled or, they can be hydro-entangled or they can
be stabilized by any combination of these methods. In a specific
example is an opened web that is easily penetrated by the particles
prior to bonding. Examples of suitable webs are carded webs
comprising a majority of multicomponent fibers that are through-air
bonded, or spunbond made from self-crimped filaments that are
thru-air bonded or point bond using a bonding pattern that
optimizes loft (e.g. using a quilted bonding pattern). A way to
describe the well-opened structure of the preferred nonwoven is by
its web porosity. Particularly suitable nonwoven used for the
disclosed composites would have a web porosity above about 90%,
e.g., above about 92%, above about 95%, or above about 99%.
[0042] Web porosity W.sub.p is defined as the % of a nonwoven
volume not occupied by the fibers or:
W.sub.p=100*[1-(WD/FD)]
where WD is the density of the web in grams per cubic centimeter
and FD is the fiber density expressed in grams per cubic
centimeter.
[0043] WD is calculated from the basis weight BW expressed as grams
per square meter and the thickness T.sub.1 of the fabric expressed
in mm as measured under a load of 0.41 KPa
WD=BW/(T.sub.1.times.10.sup.3)
[0044] FD for a bicomponent fiber can be calculated from the weight
faction of each polymer (F.sub.x) and the solid density of the
polymer PD.sub.x expressed in grams per cubic centimeter. For a
bicomponent fiber comprised of polymer a and b, FD can be
calculated as follow:
FD=(F.sub.a.times.PD.sub.a)+(F.sub.b.times.PD.sub.b)
Particles
[0045] In the disclosed composites, the relative size of the
particles to the cross-sectional dimension of the fibers to which
they are attached is a significant parameter. Small particles offer
more surface per gram of particles than larger ones. Also, the
composite should contain a maximum load of particles, and as much
of the surface of the fiber should be covered with the particles as
possible. Thus, without wishing to be bound by theory, it is
believed that more than about two thirds (66%) of the particles
attached to the fibers should have an average apparent diameter
that is equal or smaller than about 100% the average apparent
diameter of the fiber, and preferably smaller than about 75% the
average apparent diameter of the fiber, and preferably smaller than
about 50% the average apparent diameter of the fiber, even more
preferably smaller than about 33% the apparent diameter of the
fiber and finally, more preferably smaller than about 25% the
apparent diameter of the fiber.
[0046] Average apparent diameter of the particle is the diameter of
a smallest sphere that can contain entirely the particle. When
smaller particles agglomerate into larger ones, the agglomerate is
considered a "particle" as used herein.
[0047] Average apparent diameter of the fiber is the average width
of the fibers as measured at random for several fibers with a
microscope. This applies to non-round fibers where the standard
deviation may be greater as the orientation of the fiber
change.
[0048] A result of having a majority of the particles smaller than
the fiber diameter is that most of the particles are attached to
only one fiber at a time, e.g., more than about 75%, 85%, or 95% of
the particles can be attached to only one fiber at a time. This is
a difference with prior methods and reflects the high particle
surface to fiber surface ratio for the disclosed composites.
[0049] Another aspect is the loading of particles onto the fibers
and into the composite. The disclosed composites can have at least
about 10% of the composite weight made-up of the active particles,
preferably at least about 20%, most preferably at least about 30%,
most preferably at least about 40%, and most preferably at least
about 50%.
[0050] The particles that can be used herein can have an average
diameter of from about 0.1 to about 100 microns, from about 5 to
about 10 microns, from about 10 to about 20 microns, from about 20
to about 30 microns, from about 30 to about 50 microns, from about
50 to about 100 microns, from about 0.1 to about 1 microns, from
about 0.1 to about 5 microns, from about 0.1 to about 15 microns,
from about 0.1 to about 50 microns, from about 1 to about 100
microns, from about 1 to about 15 microns, from about 15 to about
50 microns, or from about 50 to about 100 microns.
[0051] In specific examples, the particles can be absorbent or
reactive particles. For example, the particles can be carbon,
zeolites, fumed silica, alumina, titania, zirconia, clay, zeolitic
imidazole framework (ZIF), polyoxymetalates, or metal organic
frameworks (MOFs). MOFs are crystalline inorganic materials,
examples of which include UiO-66, UiO-66-NH.sub.2, ZIF-8, or ZIF-7.
While individually very small, MOFs aggregate to particles within
suitable size ranges disclosed herein.
EXAMPLES
[0052] The following examples are set forth below to illustrate the
methods and results according to the disclosed subject matter.
These examples are not intended to be inclusive of all aspects of
the subject matter disclosed herein, but rather to illustrate
representative methods and results. These examples are not intended
to exclude equivalents and variations of the present invention,
which are apparent to one skilled in the art.
General Methods
[0053] For Examples 1 to 4, MOFs were put in a beaker that was
immersed in a heated oil bath. The oil was heated and the
temperature of the powder was raised above 130.degree. C. as
measured with a thermocouple inserted in the powder. A powder
temperature of from about 130.degree. C. to about 140.degree. C.
was reached. A strip of cut fabric was dipped into the heated
powder with one side facing down and moved slowly. Then the fabric
was dipped again with the other side facing down. After that, the
fabric was shaken to remove loosely attached particles. In a few
instances, a jet of air provided by a compressed air canister was
used to remove loose particles.
Example 1
[0054] A spunbond made from Island-in-the-Sea filaments having 37
islands made from polypropylene and a sheath of polyethylene was
used in the general method. The picture of the resulting fiber
taken with a Keyence digital microscope VHX-950F is found in FIG.
2. This figure shows a partial coverage of the filaments with
particles.
Example 2
[0055] The fabric used was made from sheath:core bicomponent fibers
having a sheath made from low melting point co-polyester and a core
made from higher melting point polyester. This fabric was made by
carding the fabric and through-air bonding while pressed between
two metallic mesh belts. It had a nominal basis weight of 0.5 osy
or 17 gsm (gram per square meter). This fabric was used in the
general method and the picture of the resulting fibers taken with a
Keyence microscope is found in FIG. 3.
Example 3
[0056] The fabric used was made from sheath:core bicomponent fibers
having a sheath made from low melting point co-polyester and a core
made from higher melting point polyester. This fabric was made by
carding the fabric and through-air bonding while pressed between
two metallic mesh belts. The basis weight was 0.8 osy or about 27
gsm. FIG. 4 is the picture taken with the microscope of the
resulting fibers. It shows very good coverage of the fibers by the
MOF particles.
Example 4
[0057] A fabric of a high loft nonwoven made by carding a web from
bicomponent sheath:core fibers having a sheath made of polyethylene
and a core of polyester was used in the general method. This web
was through-air bonded without compression; therefore, it had a
high bulk and could easily be penetrated by the MOF particles
during the coating process. This web had a basis weight of
approximately 76 gsm. FIG. 5 is a microscopy picture of the coated
fibers and illustrates the level of coverage achieved.
Example 5
[0058] For this example, the fabric was coated using an apparatus
that comprises a V-shaped well immersed in a bath of heated oil
(see FIG. 6). This well contained the heated MOF particles
(typically the volume of particles in the well was from about 1 to
about 2 liters of particles). A fabric having a width of from about
250 mm to about 275 mm was unwinded from a mandrel and slowly
passed into the bed of heated powder particles before being winded
on a mandrel on the opposite side. While the fabric was immersed
into the bed of hot particles, those were pressed against the
fabric with the help of a metallic spoon to help them to penetrate
into the fabric pore (This was done to simulate what nip rolls
could do in a larger scale process). This was done twice with
different sides of the fabric facing toward the bottom of the well.
The oil temperature, the residence time, and the amount of work
performed to press the hot powder into the pores of the fabric
could be varied depending on the desired product or preference. At
the end, the excess powder that had not adhered to the filaments
was removed by shaking the fabric and blowing it with compressed
air.
[0059] The fabric used for this example was a sample of B4302G
nonwovens manufactured by Berry Global. It is a high loft
through-air bonded carded nonwoven made bicomponent fibers having a
sheath made of polyethylene and a core of polyester (A 50:50 ratio
of PE and PET was assumed). The oil temperature was controlled at
200.degree. C. and the residence time of the fabric in contact with
the hot particles was at least 90 seconds. FIG. 7 shows one side of
this sample after coating with MOF particles. Very little shrinkage
of the fabric was observed during the coating process. Large coated
pieces of the fabric were weighted after the excess powder that was
not attached to the fibers was removed by shaking and blowing with
compressed air. For a fabric having a basis weight of about 60 gsm,
a gain in basis weight of about 72 gsm or a gain in weight of about
120% was observed.
Example 6
[0060] In this example MOF particles were poured into a metallic
deep pan and a pneumatic vibrator (Vibco model VS-130) was attached
to the wall of the pan. The fabric used for this example was B4302G
made by Berry Global. This carded and through-air bonded fabric is
made from sheath:core bicomponent fibers where the sheath is made
of polyethylene and the core is made of polyester. A piece of that
fabric was put in the pan and covered with MOF particles while the
pan was vibrated with high intensity. The energy delivered by the
vibration helped the particles penetrate into the fabric structure.
This piece of fabric loaded with MOF particles was then deposited
onto a non-stick cookie sheet and covered with a fluoropolymer
coated non-stick fabric. This pan was then heated in an
air-circulated oven for 15 minutes at about 170.degree. C. After
being retrieved and while still hot, the loaded sample on the
non-stick pan and covered by the non-stick fabric was gently
compressed with a rolling pin. The purpose of the latter was to
help getting the MOF particles embedded into the polymer forming
the sheath of the fibers. The particles that were not adhered to
the fibers were shaken off and blown away using compressed air. The
results were that the sample of fabric that had an original basis
weight of 64 gsm, was measured at 124 gsm after this operation;
therefore, it had gained about 60 gsm of MOF particles. This is a
weight gain of about 94%. This sample is shown in FIG. 8.
[0061] Other advantages which are obvious and which are inherent to
the invention will be evident to one skilled in the art. It will be
understood that certain features and sub-combinations are of
utility and may be employed without reference to other features and
sub-combinations. This is contemplated by and is within the scope
of the claims. Since many possible embodiments may be made of the
invention without departing from the scope thereof, it is to be
understood that all matter herein set forth or shown in the
accompanying drawings is to be interpreted as illustrative and not
in a limiting sense.
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