U.S. patent application number 14/762758 was filed with the patent office on 2015-12-10 for wet laid non-woven substrate containing polymeric nanofibers.
This patent application is currently assigned to Xanofi, Inc.. The applicant listed for this patent is XANOFI, INC.. Invention is credited to Sumit GANGWAL, Peter GEISEN, Miles C. WRIGHT.
Application Number | 20150354139 14/762758 |
Document ID | / |
Family ID | 51228063 |
Filed Date | 2015-12-10 |
United States Patent
Application |
20150354139 |
Kind Code |
A1 |
GEISEN; Peter ; et
al. |
December 10, 2015 |
WET LAID NON-WOVEN SUBSTRATE CONTAINING POLYMERIC NANOFIBERS
Abstract
Substrates with wet laid staple polymeric nanofibers of short
lengths are disclosed. The polymeric nanofibers can be surface
coated on a non-woven or woven substrates, wet laid with other
fiber types to create a nonwoven substrate or wet laid onto
themselves to form a nanofiber-only mat.
Inventors: |
GEISEN; Peter; (Raleigh,
NC) ; GANGWAL; Sumit; (Raleigh, NC) ; WRIGHT;
Miles C.; (Raleigh, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
XANOFI, INC. |
Raleigh |
NC |
US |
|
|
Assignee: |
Xanofi, Inc.
Raleigh
NC
|
Family ID: |
51228063 |
Appl. No.: |
14/762758 |
Filed: |
January 24, 2014 |
PCT Filed: |
January 24, 2014 |
PCT NO: |
PCT/US2014/012946 |
371 Date: |
July 22, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61756949 |
Jan 25, 2013 |
|
|
|
Current U.S.
Class: |
428/219 ;
162/103; 428/220 |
Current CPC
Class: |
B82Y 30/00 20130101;
D10B 2509/00 20130101; D04H 1/4374 20130101; D10B 2505/02 20130101;
B01D 2239/025 20130101; D04H 13/00 20130101; D10B 2331/04 20130101;
D21H 13/06 20130101; D10B 2201/28 20130101; B01D 39/1623 20130101;
B01D 2239/0654 20130101; D10B 2505/04 20130101; D10B 2501/00
20130101 |
International
Class: |
D21H 13/06 20060101
D21H013/06; D04H 1/4374 20060101 D04H001/4374; D04H 13/00 20060101
D04H013/00 |
Claims
1. A porous, fabric substrate comprising a wet laid polymeric
nanofiber coating coated onto a surface of a nonwoven web or woven
fabric substrate.
2. The substrate of claim 1, wherein the fabric substrate may be
composed of fibers of cotton, cellulose, acetate, rayon, silk,
wool, hemp, polyester, spandex (including LYCRA), polyolefins
(polypropylene, polyethylene, etc.), polyamide (nylon, etc.),
aramids (e.g. Kevlar.RTM., Twaron.RTM., Nomex, etc.), acrylic,
glass microfibers, fiberglass, or poly (trimethylene
terephthalate).
3. The substrate of claim 1, wherein the nanofiber coating has a
thickness from 0.0001 to 5 mm or higher.
4. The substrate of claim 1, wherein the nanofiber coating has a
basis weight ranging from 0.001 to 1000 grams per square meter
(GSM) or higher.
5. The substrate of claim 1, wherein the polymeric nanofibers have
an average diameter ranging from 1 nm to 5 .mu.m.
6. The substrate of claim 1, wherein the polymeric nanofibers have
a length to diameter aspect ratio of 20 to 2000 or greater.
7. A porous nonwoven substrate, comprising only wet-laid nanofibers
in the form of a mat.
8. The substrate of claim 9, having a thickness ranging from 0.0001
to 30 mm or higher.
9. The substrate of claim 9, having a basis weight of 0.001 to 5000
GSM or higher.
10. A porous, fabric substrate containing wet laid staple,
polymeric nanofibers of short cut lengths, wherein the polymeric
nanofibers are wet laid throughout the loft of a nonwoven web or
woven fabric substrate.
11. The substrate of claim 10, wherein polymeric nanofibers are wet
laid together with other microfibers or nanofibers comprised of
natural, cellulose, acetate, rayon, silk, wool, hemp, polyester,
spandex (including LYCRA), polyolefins (polypropylene,
polyethylene, etc.), polyamide (nylon, etc.), aramids (e.g.
Kevlar.RTM., Twaron.RTM., Nomex, etc.), acrylic, glass microfibers,
fiberglass, or poly (trimethylene terephthalate).
12. The substrate of claim 10, wherein the thickness of the
polymeric nanofiber-containing substrate can range from 0.0001 to 5
mm or higher or have a basis weight ranging from 0.001 to 1000
grams per square meter (GSM) or higher.
13. A method of manufacturing a porous, fabric substrate,
comprising wet laying polymeric nanofibers onto a nonwoven web or
woven fabric substrate.
Description
TECHNICAL FIELD
[0001] The present invention relates generally to forming wet laid
substrates that contain polymeric nanofibers. More specifically,
the invention relates to forming a substrate with wet laid staple
polymeric nanofibers of short lengths. The polymeric nanofibers can
be surface coated on a non-woven or woven substrates, wet laid with
other fiber types to create a nonwoven substrate or wet laid onto
themselves to form a nanofiber-only mat.
BACKGROUND
[0002] Fibers form, in part or in whole, a large variety of both
consumer and industrial materials such as, for example, clothing
and other textile materials, medical prostheses, construction
materials and reinforcement materials, and barrier, filtration and
absorbent materials. There are two main structural classes of fiber
materials: woven and non-woven. An advantage of non-woven fiber
materials is their lower production cost.
[0003] Wet lay technology is essentially a paper machine process to
form nonwoven substrates. In this process fibers are suspended in
liquids and specialized paper machines are used to separate the
water from the fibers to form a uniform sheet of material, which is
then bonded and dried.
[0004] Polymeric nanofibers are increasingly being investigated for
use in various applications. Nanofibers may attain a high surface
area comparable with the finest nanoparticle powders, yet are
fairly flexible, and retain one macroscopic dimension which makes
them easy to handle, orient and organize
[0005] Accordingly, an ongoing need remains for developing wet laid
substrates containing polymeric nanofibers or nanofiber-only
substrates.
SUMMARY
[0006] The present invention comprises a fabric substrate of
cotton, synthetic or blend fibers containing wet laid polymeric,
staple nanofibers of short cut lengths (FIG. 1). The staple
polymeric nanofibers can be wet laid onto a fabric substrate of
natural, synthetic or blend fibers or the nanofibers can be wet
laid with other fibers to form a nonwoven mat or the nanofibers can
be wet laid onto themselves to form a nonwoven containing only
nanofibers.
[0007] A wide variety of polymers or biopolymers may be utilized as
starting materials, examples of which are given below.
[0008] A wide variety of fabric substrates of natural, synthetic or
blend fibers may be utilized as starting materials, examples of
which are given below.
[0009] Other devices, apparatus, systems, methods, features and
advantages of the invention will be or will become apparent to one
with skill in the art upon examination of the following figures and
detailed description. It is intended that all such additional
systems, methods, features and advantages be included within this
description, be within the scope of the invention, and be protected
by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention can be better understood by referring to the
following figures. The components in the figures are not
necessarily to scale, emphasis instead being placed upon
illustrating the principles of the invention. In the figures, like
reference numerals designate corresponding parts throughout the
different views.
[0011] FIG. 1 is a schematic of nanofibers and microfibers wet-laid
into a composite substrate.
[0012] FIG. 2 is a scanning electron micrograph of the
cross-section of a wet-laid substrate consisting of 70% by weight
PET microfibers (.about.10 micron diameter) and 30% cellulose
acetate nanofibers (.about.500 nm diameter).
[0013] FIG. 3 is a scanning electron micrograph of the surface of a
PET microfiber substrate coated on the top with cellulose acetate
nanofibers.
[0014] FIG. 4 is a scanning electron micrograph of the
cross-section of a PET microfiber substrate coated on the top with
cellulose acetate nanofibers.
DETAILED DESCRIPTION
[0015] As used herein, the term nanofiber refers generally to an
elongated fiber structure having an average diameter ranging from
less than 50 nm-2 .mu.m. The "average" diameter may take into
account not only that the diameters of individual nanofibers making
up a plurality of nanofibers formed by implementing the presently
disclosed method may vary somewhat, but also that the diameter of
an individual nanofiber may not be perfectly uniform over its
length in some implementations of the method. In some examples, the
average length of the nanofibers may range from 10 micros or
greater. In other examples, the average length may range from 110
microns to over 25 centimeters. In some examples, the aspect ratio
(length/diameter) of the nanofibers may range from 10:1 or greater.
In some specific examples, nanofibers according to the invention
have aspect ratios of at least 10,000:1. Insofar as the diameter of
the nanofiber may be on the order of two microns or less, for
convenience the term "nanofiber" as used herein encompasses both
nano-scale fibers and extremely small micro-scale fibers
(microfibers).
[0016] As used herein, the term fibril refers generally to a fine,
filamentous non-uniform structure in animals or plants having an
average diameter ranging from about 1 nm-1,000 nm in some examples,
in other examples ranging from about 1 nm-500 nm, and in other
examples ranging from about 25 nm-250 nm. According to certain
methods described below, fibrils are formed by phase separation
from nanofibers. In these methods, a fibril may be composed of an
inorganic precursor or an inorganic compound. In the present
disclosure, the term "fibrils" distinguishes these structures from
the polymer nanofibers utilized to form the inorganic fibrils. The
length of the fibrils may be about same as the polymer nanofibers
or may be shorter.
[0017] Polymers encompassed by the present disclosure generally may
be any naturally-occurring or synthetic polymers capable of being
fabricated into nanofibers. Examples of polymers include many high
molecular weight (MW) solution-processable polymers such as
polyethylene (more generally, various polyolefins), polystyrene,
cellulose, cellulose acetate, poly(L-lactic acid) (PLA),
polyacrylonitrile (PAN), polyvinylidene difluoride (PVDF),
conjugated organic semiconducting and conducting polymers,
biopolymers such as polynucleotides (DNA) and polypeptides,
etc.
[0018] Other examples of suitable polymers to form nanofibers
include vinyl polymers such as, but not limited to, cellulose
acetate propionate, cellulose acetate butyrate, polyethylene,
polypropylene, poly(vinyl chloride), polystyrene,
polytetrafluoroethylene, poly(.alpha.-methylstyrene), poly(acrylic
acid), poly(isobutylene), poly(acrylonitrile), poly(methacrylic
acid), poly(methyl methacrylate), poly(1-pentene),
poly(1,3-butadiene), poly(vinyl acetate), poly(2-vinyl pyridine),
1,4-polyisoprene, and 3,4-polychloroprene. Additional examples
include nonvinyl polymers such as, but not limited to,
poly(ethylene oxide), polyformaldehyde, polyacetaldehyde,
poly(3-propionate), poly(10-decanoate), poly(ethylene
terephthalate), polycaprolactam, poly(11-undecanoamide),
poly(hexamethylene sebacamide), poly(m-phenylene terephthalate),
poly(tetramethylene-m-benzenesulfonamide). Additional polymers
include those falling within one of the following polymer classes:
polyolefin, polyether (including all epoxy resins, polyacetal,
polyetheretherketone, polyetherimide, and poly(phenylene oxide)),
polyamide (including polyureas), polyamideimide, polyarylate,
polybenzimidazole, polyester (including polycarbonates),
polyurethane, polyimide, polyhydrazide, phenolic resins,
polysilane, polysiloxane, polycarbodiimide, polyimine, azo
polymers, polysulfide, and polysulfone.
[0019] As noted above, the polymer used to form nanofibers can be
synthetic or naturally-occurring. Examples of natural polymers
include, but are not limited to, polysaccharides and derivatives
thereof such as cellulosic polymers (e.g., cellulose and
derivatives thereof as well as cellulose production byproducts such
as lignin) and starch polymers (as well as other branched or
non-linear polymers, either naturally occurring or synthetic).
Exemplary derivatives of starch and cellulose include various
esters, ethers, and graft copolymers. The polymer may be
crosslinkable in the presence of a multifunctional crosslinking
agent or crosslinkable upon exposure to actinic radiation or other
type of radiation. The polymer may be homopolymers of any of the
foregoing polymers, random copolymers, block copolymers,
alternating copolymers, random tripolymers, block tripolymers,
alternating tripolymers, derivatives thereof (e.g., graft
copolymers, esters, or ethers thereof), and the like.
[0020] By "web" is meant a fibrous material capable of being wound
into a roll.
[0021] By "nonwoven web" is meant a web of individual fibers or
filaments which are interlaid and positioned in a random manner to
form a planar material without identifiable pattern, as opposed to
a knitted or woven fabric. Nonwoven webs have been in the past
formed by a variety of processes known to those skilled in the art
such as, for example, meltblown, spunbound, wet-laid, dry-laid, and
bonded carded web processes.
[0022] A nonwoven or woven fabric substrate or web can be made from
natural or synthetic fabrics and may be composed of fibers of
cotton, cellulose, Lyocell, acetate, cellulose acetate, rayon,
silk, wool, hemp, spandex (including LYCRA), polyolefins
(polypropylene, polyethylene, etc.), polyamide (nylon 6, nylon 6-6,
etc.), aramids (e.g. Kevlar.RTM., Twaron.RTM., Nomex, etc.),
acrylic, or polyester (polyethylene teraphthalate, trimethylene
terephthalate), polyurethane, glass microfibers, fiberglass, etc.
By "fabric blends" is meant fabrics of two or more types of fibers.
Typically these blends are a combination of a natural fiber and a
synthetic fiber, but can also include a blend of two natural fibers
or two synthetic fibers.
[0023] Nanofibers can be wet laid deposited onto a non-woven or
woven substrate, which is placed on a filter mesh of 27-200 microns
pore size as per the following example:
EXAMPLE
[0024] Wet laying process: Cellulose acetate (Eastman CA-398-10)
nanofibers (average diameter of 400 nm and lengths of
.about.200-700 .mu.m or 2-10 mm) were first wet-laid (1 to 2 grams
per square meter (GSM) of substrate) onto a fabric substrate of
polyester. The back side of the fabric substrate was cellulose
material. A dilute solution containing glycerol and water with
suspended Cellulose acetate nanofibers (.about.0.1% solids) was
poured onto the polyester fabric substrate placed on top of a
plastic filter mesh (80 mesh size). A wet-dry shop vacuum (Shop-Vac
6-Gallon 3 Peak HP) was used to pull vacuum to drain the liquid
through the filter fabric and lay the nanofibers down on top of the
polyester fabric substrate. The sample was then washed and then
heat pressed or oven baked.
[0025] Nanofibers can also be deposited onto themselves without a
substrate with basis weights ranging from 4 to 800 GSM or higher.
In this case the length is important as longer length fibers
provide mat integrity and strength.
[0026] Polymeric nanofibers can also be wet laid together with
other nano- or microfibers to form a nonwoven substrate containing
many types of fibers.
[0027] Adding polymeric nanofibers to a substrate by wet laying
techniques is novel and has not been achieved in the prior art as
nanofibers are typically produced as long (>20 cm) dry fibers by
electrospinning and meltblowing technologies. The nanofibers used
here are produced by the XanoShear process. This method allows
production of polymeric nanofibers in a liquid based process.
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