U.S. patent application number 15/788424 was filed with the patent office on 2018-04-19 for nonwoven fabrics and methods of making and using same.
The applicant listed for this patent is North Carolina State University, Sanctuary Systems Inc.. Invention is credited to Harry Barnes, Behnam Pourdeyhimi.
Application Number | 20180105965 15/788424 |
Document ID | / |
Family ID | 61903019 |
Filed Date | 2018-04-19 |
United States Patent
Application |
20180105965 |
Kind Code |
A1 |
Pourdeyhimi; Behnam ; et
al. |
April 19, 2018 |
NONWOVEN FABRICS AND METHODS OF MAKING AND USING SAME
Abstract
Substantially compostable nonwoven fabrics comprising staple
fibers made from natural cellulosic fibers optionally mixed with
other natural, man-made or synthetic fibers are described. Also
described are methods of preparing such nonwoven fabrics that can
include the steps of at least one of needle punching and/or
hydroentangling and optionally resin bonding and/or thermal
bonding. The compostable, or substantially compostable nonwoven
fabrics disclosed herein provide improved durability over
conventional nonwoven fabrics.
Inventors: |
Pourdeyhimi; Behnam;
(Raleigh, NC) ; Barnes; Harry; (Montgomery,
AL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
North Carolina State University
Sanctuary Systems Inc. |
Raleigh
Montgomery |
NC
AL |
US
US |
|
|
Family ID: |
61903019 |
Appl. No.: |
15/788424 |
Filed: |
October 19, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62410060 |
Oct 19, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A45C 3/001 20130101;
D04H 1/492 20130101; D04H 1/49 20130101; A45C 3/04 20130101; D04H
1/425 20130101; D04H 1/46 20130101; D04H 1/488 20130101; D04H
1/4382 20130101 |
International
Class: |
D04H 1/49 20060101
D04H001/49; A45C 3/04 20060101 A45C003/04 |
Claims
1. A nonwoven fabric, comprising: a needle punched and/or
hydroentangled web of nonwoven staple fibers having a first fiber
component comprising natural cellulosic fibers with fiber lengths
less than about 26 mm.
2. The nonwoven fabric of claim 1, wherein the web further
comprises a second fiber component comprising fiber lengths greater
than about 30 mm.
3. The nonwoven fabric of claim 2, wherein the second fiber
component is selected from the group consisting of PLA, PHA, a
man-made cellulosic fiber, a bicomponent fiber, and any combination
thereof.
4. The nonwoven fabric of claim 1, wherein the natural cellulosic
fibers are more than about 50% by weight based on the total weight
of the nonwoven fabric.
5. The nonwoven fabric of claim 1, wherein the web is needle
punched and/or hydroentangled at high pressure to reach an air
permeability of 150 cfm or less and a bursting strength of 30
pounds or higher, at a weight of at least 100 g/m.sup.2.
6. The nonwoven fabric of claim 1, wherein the natural cellulosic
fibers are selected from the group consisting of cotton, kenaf,
hemp, flax, ramie, pineapple, coir, and any combination
thereof.
7. The nonwoven fabric of claim 1, further comprising an acrylic or
a polyurethane resin at from about 1% to about 15% by weight based
on the total weight of the nonwoven fabric.
8. The nonwoven fabric of claim 1, wherein the fabric comprises one
or more additional webs of nonwoven staple fibers.
9. The nonwoven fabric of claim 1, wherein the nonwoven fabric
comprises a first web layer, a third web layer, and a second web
layer disposed between the first web layer and the third web layer,
wherein the web layers are needle punched and/or hydroentangled,
and at least one of the web layers is thermally bonded and
chemically bonded.
10. The nonwoven fabric of claim 9, wherein each of the first web
layer and the third web layer comprises a splittable bicomponent
staple fiber such that the entire content of the splittable
bicomponent staple fiber comprises from about 25% to about 50% by
weight of the total weight of the nonwoven fabric.
11. The nonwoven fabric of claim 10, wherein the splittable
bicomponent staple fiber has a cross-section selected from the
group consisting of side-by-side, tipped trilobal, segmented pie,
segmented ribbon, islands in the sea, and any combination
thereof.
12. The nonwoven fabric of claim 9, wherein each of the first web
layer and the third web layer is a spunbonded web comprising a
splittable bicomponent fiber and the second web layer comprises a
staple fiber bonded together mechanically by needle punching and/or
hydroentangling.
13. The nonwoven fabric of claim 12, wherein the splittable
bicomponent fiber comprises from about 25% to about 50% by weight
of the total weight of the fibers comprising the spunbonded
web.
14. The nonwoven fabric of claim 12, wherein at least a portion of
the splittable bicomponent fibers of the spunbonded web are
partially split and are entangled with at least a portion of the
staple fibers of the second web layer.
15. A bag comprising the nonwoven fabric of claim 1.
16. A method for preparing a nonwoven fabric, comprising: needle
punching and/or hydroentangling a web of nonwoven staple fibers to
form an interlaced fibrous structure, wherein the web comprises a
first fiber component comprising natural cellulosic fibers with
fiber lengths less than about 26 mm.
17. The method of claim 16, wherein before needle punching and/or
hydroentangling the web of nonwoven staple fibers is prepared by
producing a carded matrix of a fiber on a web, the fiber having a
substantially uniform basis weight; and cross-lapping the carded
matrix.
18. The method of claim 16, further comprising bonding the
interlaced fibrous structure to form a bonded fibrous
structure.
19. The method of claim 16, further comprising hydroentangling and
calendering the bonded fibrous structure to provide a surface
effect to the fabric.
20. The method of claim 16, wherein bonding the interlaced fibrous
structure comprises thermally bonding and/or chemically
bonding.
21. The method of claim 16, wherein the web comprises a second
fiber component, the second fiber component being selected from the
group consisting of PLA, PHA, a man-made cellulosic fiber, a
bicomponent fiber, and any combination thereof.
22. The method of claim 16, wherein the web is needle punched
and/or hydroentangled at high pressure to reach an air permeability
of 150 cfm or less and a bursting strength of 30 pounds or higher,
at a weight of at least 100 g/m.sup.2.
23. The method of claim 16, wherein the natural cellulosic fibers
are selected from the group consisting of cotton, kenaf, hemp,
flax, ramie, pineapple, coir, and any combination thereof.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority to U.S.
Provisional Application 62/410,060, filed Oct. 19, 2016, which is
incorporated by reference herein in its entirety.
FIELD
[0002] The subject matter disclosed herein relates to nonwoven
fabrics that are durable and substantially compostable and/or
biodegradable.
BACKGROUND
[0003] Conventional nonwoven fabrics made from entangled staple
fibers (short fibers normally measuring 30 to 50 mm) are relatively
weak and not very durable. Because of these limitations,
conventional nonwoven fabrics are mostly used in disposable market
segments such as sanitary napkins, baby wipes, household wipes,
fabric dryer sheets, and other industry-specific disposable
applications. The efficiency through which nonwoven fabrics can be
produced gives them an economic advantage over traditional woven or
knitted fabrics in these types of disposable applications.
[0004] Nonwoven fabrics have been produced through
hydroentanglement. Hydroentangled nonwoven fabrics are
alternatively known in the art as "spunlace fabrics", "spunlace" or
"spunlaced." Improvements have been made to these hydroentanglement
processes to improve the properties of the nonwoven fabric with
particular emphasis placed on the durability of the fabric and
improved fabric integrity.
[0005] A more durable nonwoven fabric may be achieved by adding
bonding agents to the fiber matrix. The fibers of nonwoven fabrics
that have been reinforced through bonding have tended to result in
fabrics that are often stiff. Further, reinforcement through the
use of bonding agents generally results in the surfaces of the
fabric having an undesirable tactile quality. Additionally, the
nature of the unsmooth, bonded nonwoven fabric surfaces are less
prone to adhering to pigments or inks, which limits the extent of
additional treatments these fabrics may undergo.
[0006] Surface effects such as images or patterns have been
imparted to nonwoven fabrics by calendaring the formed fabric
through, for example, calendar embossing rollers. More recently,
hydroentanglement techniques have also been developed to impart
images or patterns to the entangled fabric by hydroentangling the
fibers on three-dimensional image transfer devices. Images or
patterns may be imparted to nonwoven fabrics for reasons of
aesthetics and/or for purposes of imparting certain functionality
to the nonwoven fabric.
[0007] There remains a need for nonwoven fabrics that have strength
and durability allowing the fabrics to be, for instance, used as a
re-usable shopping bags or other articles. An additional need is
for nonwoven fabrics that substantially retain their desirable
features after several washings without the use of binding agents.
A further need is for processes that can produce high strength,
durable nonwoven fabrics having desirable textile features that are
both reliable and economical, and for the final product to be
compostable or biodegradable. The compositions and methods
disclosed herein address these and other needs.
SUMMARY
[0008] In accordance with the purposes of the disclosed materials,
compounds, compositions, articles, and methods, as embodied and
broadly described herein, the disclosed subject matter, in one
aspect, relates to nonwoven fabrics and methods for preparing and
using such nonwoven fabrics. In a further aspect, the disclosed
subject matter relates to durable, compostable, and/or
biodegradable nonwoven fabrics.
[0009] The disclosed subject matter, in certain aspects, relates to
a nonwoven fabric comprising a needle punched and/or hydroentangled
web of nonwoven staple fibers having a first fiber component
comprising natural cellulosic fibers with fiber lengths less than
about 26 mm. Also disclosed are articles, such as bags, comprising
the nonwoven fabrics disclosed herein. In other aspects, disclosed
are methods for preparing a nonwoven fabric that comprise needle
punching and/or hydroentangling a web of nonwoven staple fibers to
form an interlaced fibrous structure, wherein the web comprises a
first fiber component comprising natural cellulosic fibers with
fiber lengths less than about 26 mm.
[0010] In certain embodiments, the web of nonwoven staple fibers
can comprise a blend of short (e.g., less than about 26 mm) and
long (e.g., greater than about 30 mm) staple fibers. In other
embodiments, the web of nonwoven staple fibers can comprise a blend
of at least one fiber type that is a natural cellulosic fiber such
as cotton, kenaf, hemp, flax, ramie, pineapple, coir, or any
combination thereof. In some examples, the at least one natural
cellulosic fiber type can have a concentration of more than about
50% by weight based on the total weight of the nonwoven fabric.
Other fibers that can be part of the web include fibers that are a
variation of the nonwoven staple fibers, such as PLA, PHA, natural
fibers such as wool, man-made cellulosic fibers such as rayon, and
polyamides, any bicomponent fiber, or any combination thereof.
[0011] In certain embodiments, when a thermoplastic fiber such as
PLA or PHA are used, the web can be further subjected to thermal
processes to bond or emboss the fabric. In other embodiments, the
web can be subjected to a chemical or resin bonding process. In yet
other embodiments, the web can be subjected to a thermal bonding
process and a chemical or resin bonding process.
[0012] When the web is subjected to a resin bonding process, the
resin can be at least one of an acrylic and a polyurethane resin.
In other examples, the acrylic and/or polyurethane resin can have a
concentration from about 3% to about 5% by weight based on the
total weight of the web.
[0013] In an embodiment, a substantially compostable durable
nonwoven fabric can comprise more than one web layer. The more than
one web layer can be subjected to needle punching, hydroentangling,
and at least one of chemical or resin bonding and thermal bonding.
The multilayer durable nonwoven fabric can comprise a first web
layer, a third web layer, and a second web layer disposed in
between the first web layer and the third web layer. The first web
layer and the third web layer can each comprise a splittable
bicomponent staple fiber. The splittable bicomponent staple fiber
can have a concentration of at least about 25% by weight based on
the total weight of the fiber layer. The splittable bicomponent
staple fiber can have a cross-section of at least one of
side-by-side, sheath-core, tipped trilobal, islands-in-the-sea,
segmented pie, and segmented ribbon as examples.
[0014] Another aspect disclosed herein provides methods for
preparing a compostable or substantially compostable durable
nonwoven fabric including the steps of producing a carded matrix of
a fiber having a substantially uniform basis weight on a web, the
fiber having at least one of a staple fiber and a filament;
cross-lapping the carded matrix; subjecting the carded matrix to at
least one of needle punching and hydroentangling to form an
interlaced fibrous structure; and bonding the interlaced fibrous
structure through at least one of thermal bonding and chemical or
resin bonding to form a bonded fibrous structure.
[0015] In another embodiment, the method for preparing a durable
nonwoven fabric can additionally comprise the step of at least one
of hydroentangling and calendering the bonded fibrous structure to
provide a desired surface effect to the fabric.
[0016] 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 DRAWING
[0017] The accompanying FIGURE, which is incorporated in and
constitutes a part of this specification, illustrates several
aspects described below.
[0018] FIG. 1 is a flowchart of an embodiment of the invention
showing the steps of an exemplary process for producing a nonwoven
fabric.
DETAILED DESCRIPTION
[0019] The present invention now will be described more fully
hereinafter with reference to the accompanying drawing, 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.
[0020] 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 pertain 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.
[0021] 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
[0022] 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:
[0023] 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.
[0024] 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.
[0025] Ranges can be expressed herein as from "about" one
particular value, and/or to "about" another particular value. When
such a range is expressed, another aspect includes from the one
particular value and/or to the other particular value. Similarly,
when values are expressed as approximations, by use of the
antecedent "about," it will be understood that the particular value
forms another aspect. It will be further understood that the
endpoints of each of the ranges are significant both in relation to
the other endpoint, and independently of the other endpoint. It is
also understood that there are a number of values disclosed herein,
and that each value is also herein disclosed as "about" that
particular value in addition to the value itself.
[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] "Optional" or "optionally" means that the subsequently
described event or circumstance can or cannot occur, and that the
description includes instances where the event or circumstance
occurs and instances where it does not.
[0028] As used herein, a "staple fiber" means a fiber of finite
length. A staple fiber can be a natural fiber or a fiber cut from,
for example, a filament.
[0029] As used herein, a "filament" refers to a fiber that is
formed into a substantially continuous strand.
[0030] 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.
[0031] As used herein, the terms "carding" or "carded web" refers
to the process of opening and aligning staple fibers that are first
applied in a bulky bat through combing or otherwise treating to
produce a web of generally uniform basis weight.
[0032] As used herein, the term "cross-lapped" means to spread a
loose fiber, for example a filament or yarn, in a back and forth
direction that is roughly transverse to the direction of the web on
which the fiber is laid with the individual laps partially
overlapping each other such that they form an acute angle with each
other.
[0033] As used herein, "needle punching" means to mechanically
entangle a web of either non-bonded or loosely bounded fibers by
passing barbed needles through the fiber web.
[0034] As used herein, the terms "hydroentangle" or
"hydroentangling" refers to a process by which a high velocity
water jet or even an air jet is forced through a web of fibers
causing them to become randomly entangled. Hydroentanglement can
also be used to impart images, patterns, or other surface effects
to a nonwoven fabric by, for example, hydroentangling the fibers on
a three-dimensional image transfer device such as that disclosed in
U.S. Pat. No. 5,098,764 to Bassett et al. or a foraminous member
such as that disclosed in U.S. Pat. No. 5,895,623 to Trokhan et
al., both fully incorporated herein by reference for their
teachings of hydroentanglement.
[0035] As used herein, the terms "calender" or "calendering" refers
to a process for imparting surface effects onto fabrics or nonwoven
webs. Without intending to be limiting, a fabric or nonwoven web
can be calendered by passing the fabric or nonwoven web through two
or more heavy rollers, sometimes heated, under high nip
pressures.
[0036] It is understood that throughout this specification, the
identifiers "first" and "second" are used solely to aid in
distinguishing the various components and steps of the disclosed
subject matter. The identifiers "first" and "second" are not
intended to imply any particular order, amount, preference, or
importance to the components or steps modified by these terms.
[0037] 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.
Materials
[0038] In one aspect, disclosed herein are improved nonwoven
fabrics. The disclosed nonwoven fabrics comprise fibers locked into
place by various mechanisms including, but not limited to, needle
punching, hydroentanglement, and thermal and/or resin bonding. The
nonwoven fabrics can optionally be subjected to additional
post-processing techniques that conventional nonwoven fabrics would
otherwise be unable to withstand. Further, the disclosed nonwoven
fabrics can be subject to other processes like carding,
cross-lapping, and calendering.
[0039] Further, nonwoven fabrics that are produced using staple
length fibers have the tendency to abrade or pill if not
sufficiently entangled or not appropriately bonded with resins or
through thermal stabilization. The nonwoven fabrics disclosed
herein avoid this effect by combining short staple fibers with
longer ones and by, e.g., using high pressure water jets in
hydroentangling that will tie down all or nearly all surface
fibers. Furthermore, the nonwoven fabrics disclosed herein allow
the fabric to be cut or sewn without demonstrating a significant
tendency to pill in the cut or broken part of the fabric.
[0040] In certain embodiments, the short stable fibers of the
disclosed nonwoven fabrics can have a length of less than about 26
mm, less than about 24 mm, less than about 22 mm, less than about
20 mm, less than about 18 mm, less than about 16 mm, less than
about 14 mm, less than about 12 mm, less than about 10 mm, less
than about 8 mm, less than about 6 mm, less than about 4 mm, or
less than about 2 mm, where any of the stated values can form an
upper or lower endpoint of a range. The short stable fibers can be
at least about 0.5 mm, e.g., from about 0.5 mm to about 26 mm, from
about 1 mm to about 26 mm, from about 5 mm to about 26 mm, from
about 10 mm to about 26 mm, from about 10 mm to about 20 mm, from
about 5 mm to about 20 mm, from about 0.5 mm to about 20 mm, or
from about 0.5 mm to about 10 mm. In specific examples, the short
staple fibers can be cellulosic fibers.
[0041] Further, the long fibers of the disclosed nonwoven fabrics
can have a length of greater than about 30 mm, greater than about
50 mm, greater than about 1 cm, greater than about 5 cm, greater
than about 10 cm, greater than about 50 cm, or greater than about
100 cm.
[0042] Without intending to be bound by theory, the nonwoven
fabrics disclosed herein are characterized by having one or more
improved physical properties such as, for example, grab tensile
strength (e.g., ASTM D5034 that uses a tensile testing machine for
measuring the highest tensile load achieved just before a fabric
specimen tears or breaks), tongue tear strength (e.g., ASTM D2261
that uses a tensile strength test for measuring the force required
to continue a rip through a prepared fabric specimen), air
permeability (e.g., ASTM D737 for measuring the standard volume of
air drawn through a fabric specimen of a defined area at constant
temperature and pressure or the German test standard DIN 53 887 for
measuring the quantity of air drawn through a fabric specimen at a
fixed vacuum), moisture vapor transmission (e.g., ASTM E96 for
measuring transfer of water vapor through a test fabric specimen
over a fixed period of time), or any other test commonly used to
measure a property related to the strength of a fabric. Such
improvements can be realized in the longitudinal or machine
direction, the transverse or cross machine direction, or both the
longitudinal or machine direction and the transverse or cross
machine direction.
[0043] In certain embodiments, the grab tensile strength in the
machine direction of the nonwoven fabric can be at least about 30
lbs, at least about 50 lbs, at least about 100 lbs, at least about
120 lbs, at least about 140 lbs, at least about 160 lbs, at least
about 180 lbs, at least about 190 lbs, or at least about 200 lbs,
up to about 300 lbs. In other embodiments, the grab tensile
strength in the cross machine direction of the nonwoven fabric can
be at least about 30 lbs, at least about 50 lbs, at least about 80
lbs, at least about 90 lbs, at least about 100 lbs, at least about
110 lbs, at least about 120 lbs, at least about 130 lbs, or at
least about 140 lbs, up to about 200 lbs. In still other
embodiments, the tongue tear strength in the machine direction of
the nonwoven fabric can be at least about 2.0 lbs, at least about
4.0 lbs, at least about 6.0 lbs, at least about 10.0 lbs, at least
about 15.0 lbs, or at least about 20.0 lbs, up to about 30.0 lbs.
In further embodiments, the tongue tear strength in the cross
machine direction of the nonwoven fabric can be at least about 2.0
lbs, at least about 5.0 lbs, at least about 8.0 lbs, at least about
10.0 lbs, at least about 15.0 lbs, or at least about 20.0 lbs, up
to about 30.0 lbs. Alternatively, the grab tensile strength and/or
the tongue tear strength can be expressed as a ratio relative to
the basis weight of the nonwoven fabric. Such ratios typically
being expressed as either in the machine direction or the cross
machine direction of the nonwoven fabric in units of lbs of force
per grams per square meter or "gsm".
[0044] In specific embodiments, the nonwoven fabrics disclosed
herein can be specifically described in terms of durability of the
fabric. The desired durability is typically established based on,
among other things, the application where the fabric is intended to
be used or the number of washes the fabric should be capable of
sustaining. For example, in certain embodiments, the nonwoven
fabric can be capable of sustaining at least 1 wash, at least 2
washes, at least 3 washes, at least 5 washes, at least 7 washes, at
least 10 washes, at least 15 washes, at least 20 washes, at least
25 washes, at least 30 washes, at least 35 washes, at least 40
washes, at least 45 washes, or at least 50 washes under
temperature, detergent solution, bleaching, and abrasive action
conditions according to AATCC (American Association of Textile
Chemists and Colorists) 61 wash test standard 2A for
laundering.
Methods
[0045] Also disclosed herein are methods for the production of a
nonwoven fabric. The disclosed methods can comprise any one or more
of the following steps: producing a carded matrix of staple fibers,
filaments, or combinations thereof having a substantially uniform
basis weight on a precursor web; cross-lapping the carded matrix of
staple fibers, filaments, or combinations thereof needle punching
the carded and/or cross-lapped web of staple fibers, filaments, or
combinations thereof entangling or interlacing the fibers, such as
by hydroentanglement; bonding the fibers through a thermal bonding
or resin bonding technique; and hydroentangling or calendaring the
formed fabric to provide a desired surface effect to the
fabric.
[0046] There are many combinations using any number of the steps of
the disclosed methods as described herein for producing a nonwoven
fabric. FIG. 1 is a flowchart illustrating a non-limiting exemplary
embodiment of how some of the steps disclosed herein can be used to
produce a nonwoven fabric. In this exemplary embodiment, a carded
and/or cross-lapped web of fibers, for example staple fibers, can
be subjected to needle punching, hydroentangling, or both needle
punching and hydroentangling. Stitch-bonded fibers only subjected
to needle punching can be bonded by at least one of resin bonding
or thermal bonding. Entangled and interlaced fibrous structures can
be directed to a calendering step for imparting texture and/or a
surface effect on the nonwoven material. Alternatively, entangled
and interlaced fibrous structures can be first bonded by at least
one of resin bonding or thermal bonding and then subjected to a
calendering step for imparting texture and or a surface effect on
the nonwoven material. Fibers only subjected to needle punching
will also preferably be subjected to a calendering step for
imparting texture and/or a surface effect on the nonwoven material.
Optionally, the nonwoven fabric can be subjected to post-treatment
processes. Non-limiting examples of post-treatment processes
include dyeing, printing, and combinations thereof.
[0047] A precursor web is formed embodying a carded fibrous matrix
of staple fibers, filaments, yarns, or combinations thereof that
has optionally also been cross-lapped. In certain embodiments, the
precursor web can be formed only of a carded fibrous matrix. In
other embodiments, the precursor web can be formed only of
cross-lapped fibers.
[0048] Exemplary processes for producing a carded web include
conventional air-laying processes known in the art such as those
disclosed in U.S. Pat. No. 4,640,810 to Laursen et al. and U.S.
Pat. No. 5,527,171 to Soerensen. In the air-laying processes,
generally, a mat of fibers is fed down a chute into an air-laying
apparatus that entrains the fibers into an airstream. Loose fibers
fall from the airstream and are collected as a fibrous web material
on a forming surface. Another type of carding process comprises the
steps of disposing a mass of loose fiber on a supporting structure,
repeatedly combing the disposed fibers with a multitude of needles,
and repeating these steps until the desired thickness of a carded
fibrous matrix is achieved. Any process for producing a carded web
now known or later invented can be used in the inventive process
for producing nonwoven fabrics. Any cross-lapping apparatus now
know or later invented can be used to cross-lap the carded matrix
of staple fibers, filaments, or combinations thereof.
[0049] In one aspect, the disclosed methods provide a nonwoven
fabric. The nonwoven fabric can be formed from a single fiber type
or a fiber blend. The nonwoven fabric can be described in terms of
a first fiber component and a second fiber component. In certain
embodiments, the first fiber component can comprise 100% by weight
of the total fiber content of the nonwoven fabric. For example,
while not intending to be limiting, the nonwoven fabric can be
formed of a polyester fiber. In other embodiments, the nonwoven
fabric can comprise the first fiber component and a certain content
of a second fiber component. In other embodiments, the second fiber
component can comprise one or more types of fibers. For example,
while not intending to be limiting, the nonwoven fabric can be
formed of a polyester/nylon fiber blend. Of course, reference to a
first fiber component and a second fiber component does not limit
the number of fiber components that can be used to prepare the
nonwoven fabric. For example, when the nonwoven fabric is formed of
a fiber component in addition to the first fiber component, the
nonwoven fabric can be formed of two, three, or even more different
types of fibers.
[0050] In certain embodiments, the nonwoven fabric comprises a
first fiber component that is selected from at least one of a
staple fiber, a filament, and combinations thereof. Preferably, the
nonwoven fabric comprises a first fiber component that is a staple
fiber. More preferably, the nonwoven fabric comprises a first fiber
component that includes at least one fiber component comprising a
polyester.
[0051] In a preferred embodiment, the nonwoven fabric is formed of
a fiber blend comprising a first fiber component having high
thermal stability. Preferably, the concentration of the first fiber
component having high thermal stability is at least about 50% by
weight of the total weight of the fibers. Yet even more preferably,
the nonwoven fabric is formed of a fiber blend comprising a first
fiber component having high thermal stability wherein the fiber
having high thermal stability is the dominant fiber by weight based
on the total weight of the fibers. In further embodiments, the
first fiber component can comprise at least about 55% by weight, at
least about 60% by weight, at least about 65% by weight, at least
about 70% by weight, at least about 75% by weight, at least about
80% by weight, at least about 85% by weight, at least about 90% by
weight, or at least about 55% by weight of the total weight of the
fibers present in the inventive nonwoven fabric. Nonlimiting
examples of materials that impart high thermal stability to fibers
include man-made cellulosics such as rayon, natural cellulosic
fibers such as cotton, hemp, Kenaf, Ramie, etc.
[0052] The second fiber component (or further fiber components) can
be chosen from a variety of fiber types, including natural fibers,
synthetic fibers, or a combination thereof. Other types of fibers
that can be included in the nonwoven fabric include variations of
the fibers as disclosed herein or blends of different fibers
including, but not limited to, PLA, PHA, Rayon, Tencel, or any
other bicomponent fiber. In a preferred embodiment, the nonwoven
fabric includes a blend of PLA fibers and PHA fibers. More
preferably, the concentration of PLA fibers will range from about
0.1 wt % to about 20 wt %, from about 0.5 wt % to about 50 wt %, or
from about 1 wt % to about 90 wt % all based on the total weight of
the fibers.
[0053] In certain embodiments, the disclosed nonwoven fabrics can
comprise a second fiber component that includes a fiber with a
melting point that is lower than the melting point of the first
fiber component. Accordingly, the first fiber component and the
second fiber component can be characterized in terms of their
melting point (e.g., a first fiber component having a first melting
point and a second fiber component having a second melting point
that is less than the first melting point). Likewise, the nonwoven
fabric can comprise a bicomponent fiber having a first component
and a second component wherein the second component has a melting
point that is lower than the melting point of the first
component.
[0054] In yet other embodiments, the nonwoven fabric can include
splittable fibers, such as splittable bicomponent fibers, that are
designed to split into finer fibers as they are processed. Without
intending to be limiting, uses for nonwoven fabrics having
splittable fibers include wipes where smaller fibers are useful for
picking up small pieces of dust, filtration, and insulation
materials.
[0055] In other embodiments, the nonwoven fabric can comprise at
least one multicomponent fiber. In a preferred embodiment, the
multicomponent fiber is a bicomponent fiber. In yet another
preferred embodiment, the multicomponent or bicomponent fiber has
at least one component that is thermally stable as described
herein. In another preferred embodiment, the multicomponent or
bicomponent fiber has at least once component that is thermally
stable that is the dominant component within the multicomponent or
bicomponent fiber. For example, the thermally stable component will
comprise the `island` or the `core` filaments respectively, while
the `sea` or `sheath` component will enhance the bonding. Such
embodiments can be an effective substitute for the binder fibers,
e.g., PLA, of certain other embodiments of the invention.
[0056] Needle punching can be used to better interlock the carded
and/or cross-lapped web of staple fibers, filaments, or
combinations thereof. Needle punching can improve properties
related to, for example, strength, absorption, and resistance to
unraveling. The fibrous matrix is fed along a feed path into a
needle loom. Any needling loom known in the art can be used in the
disclosed methods such as, for example, a Dilo needle loom. A
needle loom generally includes a reciprocally moving needle carrier
for carrying a series of needles arranged in spaced rows or lines
along the length of the carrier. The needle carrier is positioned
such that when it is reciprocally engaged with the bed of the
fibrous matrix structure, the barbs of the needles engage and pull
fibers through the body of the fibrous matrix causing the engaged
fibers to intertwine among other fibers within the carded and
cross-lapped fibrous matrix. Without intending to be bound by
theory, the interlocking that occurs causes the finished fabric to
become generally more resistant to unraveling.
[0057] In one embodiment, the needle bed of the needle loom is
substantially flat. In another embodiment, the needle bed of the
needle loom is curved. In certain embodiments, a curved or an
arcuate bed can be preferred since it increases the effectiveness
of the interlocking that occurs in the fibrous matrix because the
needles enter the fibrous matrix structure at varying angles.
[0058] Hydroentanglement further serves to entangle or interlace
the fibers of the stitch-bonded fibrous structure. The fibers of
the stitch-bonded fibrous structure can be interlaced by any
hydroentanglement process known in the art. For example, one or
more water jets under pressure can be directed at one or both sides
of the base fibrous structure to cause the fibers to become
entangled in a repeating pattern of localized entangled regions.
The localized entangled regions can in turn become interconnected
by fibers extending between adjacent entangled regions. In another
exemplary process, hydroentanglement includes applying a jet of air
to the nonwoven material to dry, cure, and/or bond the fibers of
the nonwoven material. While not intending to be limiting, the
dwell time, temperature and velocity of the air can be adjusted to
achieve the desired degree of entanglement and/or bonding in the
nonwoven fabric. An example of such a bonding system includes the
rotary and the flatbed THRU-AIR.TM. Systems commercially available
from the Honeycomb Division of Metso Paper (Helsinki, Finland).
[0059] Hydroentanglement causes the fibers to turn, wind, twist
back-and-forth passing about one another in a random but intricate
entanglement causing the fibers to become interlocked. Regions of
fiber entanglement can extend substantially continuously along
straight paths or can be distinct entangled masses of other
appearances. Patterns having distinct regions of entangled fibers
formed within the fibrous structure can be controlled by the
apertures of the supporting web on which the fibrous structure is
carried. Repeating patterns of distinct regions of fiber
entanglement can be made to be regular wherein substantially
identical arrangements are repeated periodically in at least one
direction in the plane of the fabric, or the repeating pattern of
distinct regions of fiber entanglement can be made to be irregular.
A key to durability of the structure is that there are at least 3
manifolds with each having pressures in the range of 50 bar to 300
bar.
[0060] In an embodiment, the interlaced fibrous structure is bonded
through a resin bonding technique wherein a sufficient amount of
resin is added to the interlaced fibrous structure to achieve a
desired strength in the fabric. Non-limiting examples of resins
include acrylics, polyurethanes, latexes, and any combination
thereof. In one embodiment, the resin is impregnated in the
interlaced fibrous structure. In other embodiments, the resin is
applied by passing the interlaced fibrous structure through a bath
of the resin. In yet other embodiments, the interlaced fibrous
structure is sprayed with the resin. Indeed, any process known in
the art for applying resins can be used in the methods disclosed
herein.
[0061] In certain embodiments, the resin is heated and cured to
enhance the strength and the durability of the structure.
Preferably, the amount of heat during curing will be sufficient to
partially melt a secondary fiber and/or fiber component that has
been included in the structure to cause additional bonding to occur
within the fibrous structure.
[0062] In an embodiment, the functional groups of the resin, such
as, for example, amine groups, epoxy groups, or any combination
thereof, are selected to promote the type of bonding that is
desired to be achieved in the interlaced fibrous structure. For
example, in one embodiment, the functional groups of the resin are
selected to promote bonding within the resin itself. In other
embodiments, the functional groups of the resin are selected to
promote bonding with one or more of the types of fibers included in
the fibrous structure. In yet other embodiments, the functional
groups of the resin are selected to promote bonding both within the
resin itself and with one or more of the types of fibers included
in the fibrous structure.
[0063] In certain embodiments, the concentration of resin bonding
agent included in the nonwoven fabric is less than about 10% by
weight of the total weight of the nonwoven fabric. In other
embodiments, the concentration of bonding agent included in the
nonwoven fabric is less than about 9%, about 8%, about 7%, about
6%, about 5%, about 4%, about 3%, about 2.5%, about 2%, about 1.5%,
about 1%, or about 0.5% by weight of the total weight of the
nonwoven fabric. In certain embodiments, the amount of resin
applied to the interlaced fibrous structure is chosen based on the
durability desired for the finished fabric. Fabric durability can
be evaluated by the various means described herein.
[0064] Preferably, the resin will have at least one of an acrylic
or polyurethane. More preferably, the resin having at least one of
an acrylic or polyurethane will have a concentration from about 3%
to about 5% by weight based on the total weight of the nonwoven
fabric.
[0065] Optionally, an image, pattern, or other surface effect can
be imparted to the nonwoven fabric. Techniques for imparting an
image, pattern, or surface effect to the nonwoven fabric include
hydroentanglement processes as already described herein and
calendering. Indeed, any process known in the art for imparting an
image, pattern, or surface effect to a web can be used in the
disclosed methods.
[0066] While images, patterns, or other surface effects can be for
aesthetic purposes, such processing techniques can also be used to
influence other properties of the nonwoven fabric. For example,
calendering the nonwoven can help to smooth the surface of the
finished fabric. Calendering can also be useful in achieving a
desired thickness of the nonwoven fabric when thickness is
important for a particular application. As would be understood by a
person having ordinary skill, when the thickness of a formed
nonwoven fabric is reduced by a calendering process, the density of
the fabric becomes increased. While helping to achieve a certain
thickness, calendering can also be useful for eliminating
variations in thickness of the nonwoven fabric.
[0067] Additionally, the mesh of the belt can be chosen not only to
provide a desired texture to the inventive nonwoven fabric but also
to affect the desired properties of the inventive nonwoven fabric.
As used herein, the term "mesh count" refers to the number of
openings per lineal inch of a mesh screen. The openings are
delineated by strands, typically plastic threads or wires, in the
mesh screen. Optionally, the mesh count can be selected to be
substantially the same or different in the longitudinal or machine
direction (MD) and the transverse or cross machine direction (CD).
Non-limiting examples of properties of the inventive nonwoven
fabric that can be affected by patterning imparted by, for example,
a belt mesh include grab tensile strength, tongue tear strength,
and any combination thereof in at least one direction MD and CD of
the inventive nonwoven fabric. In an embodiment, the mesh size is
less than about 100 mesh, less than about 50 mesh, less than about
40 mesh, less than about 30 mesh, less than about 25 mesh, and less
than about 20 mesh. In a preferred embodiment, the mesh size is
less than about 14 mesh. In another preferred embodiment, the mesh
size is substantially equal to about 14 mesh. In yet another
preferred embodiment, the mesh is a herringbone mesh screen. In
another embodiment, the diameter of the strands of the mesh screen
are selected to achieve a preferred property of the inventive
nonwoven fabric, for example, any such property for the nonwoven
fabric as disclosed herein.
[0068] In an embodiment, the basis weight, or the weight per unit
surface area, of the nonwoven fabric will affect the properties of
the nonwoven fabric. In an embodiment, the basis weight of the
fabric will be at least about 50 grams per square meter (gsm), at
least about 100 gsm, at least about 120 gsm, at least about 130
gsm, at least about 140 gsm, at least about 150 gsm, at least about
160 gsm, at least about 170 gsm, at least about 180 gsm, or at
least about 200 gsm, up to about 500 gsm. Without intending to be
limiting, generally, when all other factors are constant,
increasing the basis weight of the nonwoven fabric will cause the
strength or, more specifically, a property measurement related to
the strength of the nonwoven fabric to become increased.
[0069] In an embodiment, the process for producing a nonwoven
fabric comprises forming two or more layers of carded and/or
cross-linked matrices of staple fibers, filaments, or combinations
thereof. The fibers of each of the layers are at least one of
needle punched, hydroentangled, interlaced, resin bonded, and
thermal bonded. Each of the layers of the nonwoven fabric can also
be subjected to at least one of needle punching, hydroentangling,
resin bonding, and thermal bonding to form additional
fiber-to-fiber bonds.
[0070] In another preferred embodiment, the nonwoven fabric
comprises three layers of carded and/or cross-linked matrices of
staple fibers as disclosed above, and at least one of the first
layer and the third layer is a spunbonded splittable fiber web and
the second layer, disposed between the first layer and the third
layer, is a staple fiber web, or a web comprising a staple fiber.
Preferably, this three-layer web is needle punched and/or
hydroentangled, and subjected to at least one of resin bonding or
thermal bonding to form additional fiber to fiber bonds.
[0071] Many variables, even beyond those processing variables as
described herein, can impact the characteristics of the nonwoven
product produced by the inventive process. Examples of variables
that will be determinative of the type of nonwoven product that can
be produced include, but are not limited to, the initial material
or materials used in the formation of the fibrous web, types and
amounts of staple fibers versus filaments used in the formation of
the fibrous matrix structure, the patterning that occurs during the
carding and cross-lapping steps, the nature and physical
characteristics of the fibers used in the formation of the fibrous
matrix structure, and the basis weight of the fabric.
[0072] In another embodiment, the disclosed nonwoven fabrics can
include one or more additives. Such additives can include, for
example, fire retardants, anti-static agents, antimicrobials, or
any other type of additive commonly used in fabrics for personal
and commercial use. In an embodiment, the additives can be included
in the fibers of the fiber matrix. In another embodiment, the
additives can be included in at least one of the fiber types of a
fiber blend. In yet another embodiment, the additive can be
disposed substantially at the surface of the fibers of the fiber
matrix or the surface of at least one of the fiber types of a fiber
blend.
[0073] The invention also provides a number of products of
manufacture that can be made using the nonwoven fabrics as
described herein. Applications where the inventive fabrics can be
useful include, but are not limited to, any application where the
durability of the inventive nonwoven fabrics is desirable. Such
applications include, but are not limited to, clothing or other
fabrics where multiple laundering is desired and fabrics where
nonwoven materials have traditionally been used.
Examples
[0074] The effect of varying ratios of blended Cotton and
Polylactic acid (PLA) fibers, varying amounts and types of binder,
varying fabric basis weights and several different patterns in
finished nonwoven fabrics on the grab tensile strength and the
tongue tear strength were measured. Grab tensile strength is a
measure of the breaking strength of the fabric and can be measured
by the method provided in ASTM D5034. According to ASTM D5034, the
fabric sample is placed into a tensile testing machine that grips
the fabric with two clamps, and one clamp slowly moves away from
the other clamp, which remains stationary. The grab tensile
strength is the highest tensile load achieved just before the
fabric tears or breaks. Grab tensile strength can be measured in
the machine direction and the cross machine direction of the
fabric.
[0075] Tongue tear strength is a measure of the force required to
continue a rip through the fabric and can be measured by the method
provided in ASTM D2261. According to ASTM D2261, a rectangular
piece of fabric of specific dimensions is slit in the center
approximately half-way down the short direction of the fabric. The
two ends of the slit piece are subjected to a tensile strength
test. The tongue tear strength is the highest tensile load achieved
just before the fabric begins to tear or break. Tongue tear
strength can be measured in the machine direction and the cross
machine direction of the fabric.
Examples
[0076] A set of nonwoven fabric was prepared with 100 wt % Cotton
fibers. Additionally, three sets of nonwoven fabrics were prepared
with varying ratios of Cotton to PLA fibers--75/25, 50/50, and
25/75 (Examples 2-4, respectively).
[0077] The PLA fibers measure 25 mm in length.
[0078] Each of the nonwoven fabrics had a fabric basis weight of
100, 150, and 200 g/m.sup.2 (gsm), and were patterned with a 100
mesh screen as disclosed herein using a hydroentangling belt. The
fabrics were subjected to 5 manifolds with pressures set as: 30,
50, 100, 150 and 220 bar.
[0079] The total number of samples were 12 and details are shown in
Table 1.
TABLE-US-00001 TABLE 1 Cotton/PLA (%) 25/75 50/50 75/25 100/0
Weights (g/m.sup.2) 100, 150, 200
[0080] Each of the nonwoven fabric samples were tested for weight,
thickness, burst strength, and air permeability according to the
test standards noted herein. The results for weight and thickness
are shown in Table 2.
TABLE-US-00002 TABLE 2 Actual Air Target Weight Cotton/PLA Weight
Thickness Permeability Ball Burst (g/m.sup.2) (%) (g/m.sup.2)
(.mu.m) (ft.sup.3/ft.sup.2/min) (lbf) 200 25/75 192 .+-. 1.8 1127
.+-. 7.5 78.96 .+-. 2.1 98.2 .+-. 1.6 50/50 206 .+-. 2.1 1125 .+-.
7.1 45.08 .+-. 1.4 92.8 .+-. 1.4 75/20 211 .+-. 1.8 1060 .+-. 8.4
33.94 .+-. 0.7 80.9 .+-. 2.1 100/0 207 .+-. 3.0 1011 .+-. 9.2 30.04
.+-. 1.0 70.0 .+-. 2.0 150 25/75 147 .+-. 1.3 934 .+-. 6.9 105.58
.+-. 2.2 74.5 .+-. 1.8 50/50 156 .+-. 1.8 936 .+-. 9.8 69.98 .+-.
1.4 64.8 .+-. 1.1 75/20 152 .+-. 4.0 849 .+-. 6.6 54.7 .+-. 2.7
50.2 .+-. 1.5 100/0 141 .+-. 2.5 814 .+-. 7.1 52 .+-. 2.1 41.1 .+-.
1.7 100 25/75 104 .+-. 3.1 741 .+-. 12.6 149.2 .+-. 6.4 47.2 .+-.
3.5 50/50 104 .+-. 2.9 741 .+-. 12.4 128.8 .+-. 6.4 40.1 .+-. 2.2
75/20 95 .+-. 1.7 692 .+-. 10.7 116.2 .+-. 4.0 30.0 .+-. 1.1 100/0
97 .+-. 4.1 668 .+-. 13.2 92 .+-. 5.6 30.1 .+-. 2.2
[0081] Interestingly, the addition of PLA improves the performance.
The addition of PLA improves the burst strength but also results in
higher air permeability and a slightly bulkier structure. The
higher percentage of cotton results in lower thickness, lower air
permeability and higher consolidation.
[0082] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the scope or spirit of the invention. Other
embodiments of the invention will be apparent to those skilled in
the art from consideration of the specification and practice of the
invention disclosed herein. It is intended that the specification
and examples be considered as exemplary only, with a true scope and
spirit of the invention being indicated by the following
claims.
* * * * *