Note: Descriptions are shown in the official language in which they were submitted.
CA 02025126 2000-02-03
TITLE
Stitch-Stabilized Nonwoven Fabric
BACKGROUND OF THE INVENTION
held of th Invention
This invention relates to a stitchbonded
nonwoven fabric and a process for producing it by
multi-needle stitching a nonwoven fibrous layer with two
thread systems. More particularly, the invention
concerns such a fabric and process for making it wherein
one of the thread systems is a bulkable thread, the other
is a substantially inextensible thread, and the threads
are arranged in repeating patterns to form a drapable,
durable, soft nonwoven fabric that is strong in both the
longitudinal and transverse directions.
Description of the Prio Art
Nonwoven fabrics have long been used in a
variety of applications. Unbonded (i.e., not bonded)
nonwoven fabrics most often have been used in
applications that require little strength and durability.
Such unbonded fabrics generally lack surface stability
and often come apart when washed or laundered. To
strengthen such fabrics, support layers often have been
combined with the unbonded fabric. Strength has also
been improved by bonding the fabric with a resin binder
or binder fibers incorporated in the fabric. In addition
to strengthening the fabric, bonding improves fabric
stability and durability. However, bonding also makes
the fabric stiff and boardy. Multi-needle stitching
(i.e., stitchbonding) of unbonded nonwoven fabrics has
also been used to increase fabric strength mainly in the
direction of the stitching.
SS-2625A
1
CA 02025126 2000-02-03
Use of bonded and unbonded, bulked nonwoven
fabrics in disposable swim wear, towels, wash cloths,
training pants for infants, baby wipes, scouring pads,
mattresses, cushions, sleeping bags and the like has been
disclosed, for example, by Wideman, United States Patent
4,606,964. Morman, United States Patent 4,657,802,
column 1, line 30, through Column 4, line 32, discloses a
large number of elastic nonwoven webs for use as diaper
components, filters, bandages, wearing apparel, and the
like. Neither patent mentions stitchbonded fabrics.
Multi-needle stitching machines, such as
"Arachne", "Liba", or "Mali" machines (including Malimo,
Malipol and Maliwatt machines) have been used to insert
stitches into a wide variety of fibrous substrates. Such
machines and some of the fabrics produced therewith are
disclosed by K. W. Bahlo, "New Fabrics Without Weaving",
Papers of the American Association of Textile Technology,
Inc., pages 51-54 (November, 1965). Other disclosures of
the use of such machines appear for example, in Ploch et
al, United States Patent 3,769,815, Hughes, United States
Patent 3,649,428 and Product Licensing Index, Research
Disclosure, "Stitchbonded products of continuous filament
nonwoven webs", page 30 (June, 1968). Warsop, United
States Patent 4,306,429, discloses a novel stitchbonded
fleece made with incompletely threaded front and back
bars of a multi-needle stitching machine. Hughes, United
States Patents 3,329,552 and 3,649,428, disclose other
stitchbonded fabrics made with two thread systems.
However, none of these disclosures concern stitching of a
nonwoven fibrous layer with bulkable thread.
Multi-needle stitching of nonwoven fibrous
layers with elastic thread (a type of bulkable thread) on
one-bar stitchbonding machines is disclosed by Zafiroglu,
United States Patent 4,773,238, to make dust cloths.
Although each of the aforementioned nonwoven
fabrics have been used with some success, their utility
2
CA 02025126 2000-02-03
could be significantly enhanced by improvements in their
combination of strength, softness, washability and
durability properties. An object of this invention is to
provide such an improvement.
SUMMARY OF THE INVENTION
The present invention provides a stitchbonded
nonwoven fabric made with two thread systems. The fabric
comprises a nonwoven fibrous layer that is reinforced in
a first direction with a bulkable thread which forms
Spaced-apart rows of stitches in the fibrous layer and is
reinforced with substantially inextensible thread in a
second direction which is at an angle of greater than 50
degrees with the first direction. In one embodiment of
the invention, the bulkable and the substantially
inextensible threads are each multi-needle stitched
through the nonwoven fibrous layer. In other
embodiments, reinforcement in the second direction is
provided by inlay stitches or by multiple, spaced apart,
Parallel threads laid on the surface of the nonwoven
fibrous layer and fastened thereto by the stitching of
the first thread system. Usually, the weight of the
threads amounts to no more than 20% of the total weight
of the nonwoven fabric, but for economy, often 2 to 10%,
and sometimes as little as 3 to 5%. Suitable bulkable
thread includes textured thread of polyester, nylon,
polypropylene, or the like, and composite thread such as
elastomeric yarn (e. g., spandex) in an extended state
wrapped with inelastic nylon or polyester. Usually, the
stitchbonded nonwoven fabric has a unit weight in the
range of 10 to 300 grams per square meter, preferably 20
to 200 g/m2. The row spacing usually is in the range of
2 to 10 rows per centimeter, preferably 3 to 6 per cm.
The stitch spacing usually is in the range of 2 to 15
stitches/cm, preferably 4 to 12 per cm.
Bulking of the bulkable threads (a) increases
entanglement of the threads with the fibrous layer and
3
CA 02025126 2000-02-03
enhances fabric stability and durability, and (b) causes
gathering of the fabric, which results in a softer hand,
improved drape, and decreased stiffness.
The present invention also provides a process
for making the above-described stitchbonded nonwoven
fabric. In accordance with the process, a fibrous layer,
weighing in the range of 15 to 150 grams per square
meter, is fed to a multi-needle stitching machine
equipped with a two-thread system. The first thread
system is a bulkable thread which is stitched into the
fibrous layer in parallel rows of stitches at a spacing
in the range of 2 to 8 rows per centimeter and with the
stitches within each row having a spacing in the range of
1 to 7 stitches per centimeter, preferably 2 to 5 per cm.
The bulkable thread is stitched under sufficient tension
so that, if the bulkable thread is a textured yarn, the
textured yarn is essentially straight and, if the
bulkable thread is wrapped elastomeric yarn, the wrapping
thread is essentially straight. The bulkable yarn
reinforces the fabric in a first direction. The second
thread system is a substantially inextensible thread that
is incorporated to provide reinforcement in a second
direction which forms an angle of greater than 50 degrees
with the first reinforcing direction. The inextensible
thread can be incorporated by stitching within the same
ranges of the row spacing and stitch spacing as in the
first thread system. In other embodiments of the
process, the inextensible thread, rather than being
stitched into the fibrous layer, is incorporated as inlay
stitches, or is laid onto the fibrous layer in multiple,
spaced apart, parallel rows and then fastened to the
layer by the bulkable thread stitching. In each
embodiment of the process, the stitching thread is under
sufficient tension to maintain, after stitching, its
original length. After the stitching operation, tension
on the stitching threads is released threads, the
4
CA 02025126 1999-06-28
bulkable threads are t>ulked and the area of the fabric is thereby reduced by
5 to 80%.
Further aspecla of the present invention are as follows:
A stitchbonded nonwoven fabric made with two mufti-needle stitched thread
systems, the first thread system being a bulkable thread and the second thread
system
being a substantially inextensible thread, the fabric comprising a nonwoven
fibrous layer
reinforced in a first direction with the bulkable thread forming spaced-apart
rows of
stitches in the fibrous layer and reinforced in a second direction with the
substantially
inextensible thread forming spaced-apart rows of stitches in the fibrous
layer, the second
direction being at an angle of at least 50 degrees with the first direction.
A stitchbonded nonwoven fabric made with two mufti-needle thread systems,
the first thread system being a bulkable thread and the second thread system
being a
substantially inextensible thread, the fabric comprising a nonwoven fibrous
layer
reinforced in a first direction with the bulkable thread forming spaced-apart
rows of
stitches in the fibrous layer and reinforced in a second direction with the
substantially
inextensible thread forming spaced-apart rows of stitches, the second
direction being
at an angle of at least 50 degrees with first direction and the reinforcement
in the
second direction being provided by inlay stitches.
A process for making a stitchbonded nonwoven fabric comprising:
feeding a fibrous layer, weighing in the range of 15 to 150 grams per square
meter, to a mufti-needle stitching machine equipped with two thread systems,
supplying the first thread system with a bulkable thread,
mufti-needle stitching the bulkable thread into the fibrous layer in parallel
rows of stitches at a spacing in the range of 2 to 8 rows per centimeter and
with the
stitches within each row at a spacing in the range of 1 to 7 stitches per
centimeter, the
bulkable thread being stitched under sufficient tension to maintain the
bulkable thread
straight during the stitching, to reinforce the fabric in a first direction,
supplying the second thread system with a substantially inextensible thread,
and
mufti-needle stitching the inextensible thread with the fibrous layer to form
parallel rows of stitches at a spacing in the range of 2 to 8 rows per
centimeter and
with stitches within each row at a spacing in the range of 1 to 7 stitches per
CA 02025126 1999-06-28
Sa
centimeter, to reinforce the fabric in a second direction, the second
direction forming
an angle of at least 50 degrees with the first reinforcing direction.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be readily understood by reference to the drawings in
which:
Figure 1 is a diagrammatic representation of a fabric of the invention made by
mufti-needle stitching into a nonwoven fibrous layer (not shown) chain
stitches of
bulkable threads 10 and 1-0, 3-4 "tricot" stitches of substantially
inextensible threads
20;
Figure 2 is a similar diagrammatic representation of a fabric of the invention
in
which chain stitches of bulkable threads 10 were mufti-needle stitched into a
nonwoven fibrous layer (not shown) over an array of parallel, substantially
inextensible threads 2.0 that were laid onto the fibrous layer; and
Figure 3 is a dliagram that shows the angles formed by a typical intersection
of
the reinforcing directions of the two thread systems (i.e., the intersection
of the thread
portions that are located between successive courses of stitches placed in the
fibrous
layer.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The invention will now be described in detail with regard to a preferred
stitchbonded fabric oif the invention. The fabric is made from a fibrous layer
and two
thread systems, one thread system being of bulkable thread which provides
reinforcement in a first direction, and the second thread system being of
substantially
inextensible thread which provides reinforcement in a second direction that is
at an
angel of at least 50 degrees with the first reinforcement direction.
Various starting fibrous layers are suitable for use in the present invention,
such as batts of carded fibers, air-laid fiber batts, wood-pulp papers,
lightly bonded
and unbonded nonwoven sheets, and the like. The
CA 02025126 2000-02-03
term "fiber", as applied to the fibrous layer, means
staple fibers of textile denier, pulps, fibrids and the
like. The fibers can be natural fibers or of synthetic
organic polymer. The fibrous layer batts or sheets
usually are supplied in wound-up rolls. If heavier
fabrics are desired, two or more batts or sheets can be
positioned upon each other to form the fibrous layer for
subsequent stitching. However, a single batt or sheet is
preferred for easier processing and lower cost.
As used herein, the term "bulkable thread"
refers to a thread or yarn which is "bulked" by being
deformed out-of plane. The deformation is induced by
releasing tension from the thread or by exposing the
thread to chemical action, moisture and/or heat at a
temperature of about 50 to 200oC.
The term "gathered" is used herein to describe
the surface of the stitchbonded nonwoven fabric of the
invention and to indicate that the final fabric area is
no more than 95% of area of the fibrous layer from which
it was made, (that is, the area before the fibrous layer
was multi-needle stitched and/or bulked).
In accordance with the process of the present
invention, the stitching operation is performed with a
conventional multi-needle stitching ("stitchbonding")
machine, equipped to handle two yarn systems. Malimo or
Liba stitching machines are particularly useful.
Substantially any strong bulkable thread is
suitable as the stitching in the first direction. The
bulkable thread provides a force that causes the fibrous
layer to contract or gather when the thread is subjected
to a bulking treatment (e. g., exposure to moisture,
steam, heat, or chemicals).
A particularly preferred bulkable thread is
formed from spandex elastomeric yarn of high elongation
and retractive power which has been wrapped with an
inelastic, substantially inextensible yarn. Such threads
6
CA 02025126 2000-02-03
are available commercially. The bulkable thread is
stitched into the sheet under substantial tension so that
the substantially inextensible wrapping yarn is straight
and so that the bulkable thread will retract during the
bulking step to as little as 20 percent of its original
length after bulking.
Any substantially inextensible thread can be
used for stitching i~ the second direction. Inextensible
threads of nylon or polyethylene terephthalate are
preferred. The substantially inextensible thread adds
strength to the fabric in a direction that is at an angle
of at least 50 degrees to the reinforcing direction of
the bulkable thread stitching. The substantially
inextensible thread is substantially inextensible while
being stitched and its length is not be substantially
increased after stitching. However, the substantially
inextensible thread can be a bulkable thread which is
substantially inextensible during the stitching but then
retracts and becomes shorter and and as a result is
extensible after bulking. A preferred bulkable thread
used in the capacity of a substantially inextensible
thread is the aforementioned elastomeric yarn wrapped
with inextensible yarn and stitched under tension
sufficient to straighten the wrapping yarn.
Usually the threads supplied by the two thread
systems amount to no more than 20% of the weight of the
stitchbonded fabric. For economy however, the weight of
stitching thread often amounts to only 2 to 10% of the
total fabric weight and sometimes as little as 3 to 5%.
In a preferred embodiment of the invention, the
first system of bulkable thread forms rows of chain
stitches in and along the length of the fibrous layer.
In another embodiment the bulkable thread forms a series
of interlocked loops on one surface of the fibrous layer
and a parallel series of zigzag tricot stitches on the
other surface. Such rows of stitches are typical of
7
CA 02025126 2000-02-03
those made by a "Mali" or an "Arachne" or "Liba"
multi-needle stitching machine. With regard to area
contraction or gathering caused by retraction of the
bulkable stitching, chain stitches cause almost all
gathering to be in the longitudinal direction of the
stitched layer and tricot stitches cause gathering across
the width as well as along the length of the fabric.
In accordance with the invention, the second
thread system provides multi-needle stitching and
reinforcement in the second direction with substantially
inextensible thread. The thread forms chain stitches,
tricot stitches, inlay stitches or any other commonly
used stitching, with the proviso that the angle between
reinforcing directions of the bulkable and inextensible
threads is at an angle of at least 50 degrees. In an
alternative embodiment, multiple, spaced apart, parallel
substantially inextensible threads are arrayed on a
surface of the fibrous layer and stitched to the layer by
the bulkable thread system.
In the manufacture of nonwoven fibrous layers
used as starting materials for the stitchbonded fabrics
of the invention, more strength is usually developed in
the longitudinal (machine or "MD") direction than in the
transverse (cross-machine or "XD") direction. For the
stitchbonded fabrics of the present invention, it is
advantageous to arrange the bulkable threads in the
stronger or longitudinal direction and the substantially
inextensible threads in the weaker or transverse
direction. Reference herein to a first direction
generally means the longitudinal direction ("MD") and
reference to a second direction generally means the
transverse direction, although such is not required.
The rows of stitches generally have a spacing in
the range of 1 to 7 stitches per cm, preferably 2 to 5.
Chain stitching with bulkable thread is preferred in the
first direction thread and "tricot" stitching with
8
CA 02025126 2000-02-03
substantially inextensible thread is preferred in the
second direction.
With reference to the drawings attached hereto,
note that Figure 1 represents a stitchbonded fabric of
the invention in which bulkable thread 10 is in the form
of chain stitching in the strong direction of the
starting nonwoven fibrous layer and inextensible thread
20 is in the form of 1-0,3-4 "3-across tricot" stitching
in the weak direction of the nonwoven fibrous layer. The
angle between the reinforcing directions of the two
thread systems is greater than 50 degrees. (The method of
determining the angle is given hereinafter with regard to
Figure 3.) For the fabric rep[resented in Figure 1, the
angle would be at least 72 degrees, if the stitch spacing
and needle spacing were equal.
Figure 2 represents a stitchbonded fabric of the
invention in which bulkable thread 10 forms chain
stitches in the strong ("MD") direction of the nonwoven
fibrous layer, inextensible thread 20 is arrayed on the
surface of the fibrous layer parallel to the weak
direction of the fibrous layer with the chain stitching
of bulkable thread l0 fastening the array to the layer.
The angle between the reinforcing directions of the two
thread systems is 90 degrees.
Usually, the inextensible threads are stitched,
laid in or arrayed in the transverse (i.e., the usually
weaker) direction of the fibrous nonwoven layer. In some
instances however, for example, when the fibrous layer is
formed by crosslapping, the transverse direction may be
the strong direction of the fabric. Under such
circumstances, it is often preferable to use the bulkable
thread in the transverse direction to apply tricot or
other patterned stitches.
Fabric characteristics and properties are
measured by the following procedures.
Unit weight of the starting fibrous layer and of
9
CA 02025126 2000-02-03
the final stitchbonded fabric are measured in accordance
with ASTM D 3776-79. The weight of thread per unit area
of fabric is determined by removing and weighing the
thread from a given area of fabric.
Fabric weight is determined by weighing a known
area of sheet which was cut while it was flattened
between plates.
Percent area gather of a fabric is determined
measuring its dry area, before (Ai) and after (Ag) the
fabric has been wetted thoroughly with water. Drying is
performed at 250oF for 10 minutes. The wetting and
drying treatment causes the fabric to gather. Percent
area gather, %G, is then calculated by the formula
%G = 100 (Ai - Ag)/Ai.
Washability is determined by exposing a fabric
sample to repeated washing and drying cycles in a home
laundry automatic washer and tumble dryer and when
applicable, recording the total number of cycles until
failure (i.e., until the samples show tears, holes, or
other signs of disintegration, or more than 5% weight
loss). The washing and drying is conducted in accordance
with AATCC Test Method 135-1978 for washing and tumble
drying. "AATCC" is the American Association of Textile
Chemists and Colorists.
Grab strengths are measured at 70oF and 65%
relative humidity using an Instron tensile testing
machine. Grab strength is determined in general
accordance with ASTM Method D-1117-80, on a 4-inch (10.2
cm) wide by 6-inch (15.2 cm) long sample. A gauge length
of 3 inches (7.6 cm), clamps having 1-inch (2.5 cm) wide
jaws, and an elongation rate of 12 inches (30.5 cm) per
minute are used. The grab strength is reported in
pounds force. For each reported measurement, ten
determinations were made in the machine direction (MD) of
the fabric and ten were made in the transverse direction
(TD) (i.e., perpendicular to the MD). The average of the
CA 02025126 2000-02-03
MD and the TD measurements are reported separately. Grab
strengths were measured for wet (i.e.,after being
thoroughly soaked in water) and dry samples (a) as made,
(b) after one washing and (c) after five washings. The
washing and drying were conducted in the same equipment
as was used for the washability test.
The "hand split" test is a subjective
evaluation of the handling strength of a fabric. The
fabric to be tested is pressed on a smooth, flat surface
with two thumbs touching and the thumbs are repeatedly
drawn apart in an attempt to cause the fabric to split.
If the fabric splits without stitching thread breakage,
the fabric fails the test. If the fabric cannot be split
without breaking the stitching thread, the fabric passes
the test.
The angle at which the direction spaced apart
rows of stitches formed by the first thread system
intersects the second direction of the spaced apart rows
formed by the second thread system, can be determined by
plane geometry from the stitch diagrams of the two thread
systems. The angles can also be determined by simple
geometry by examining the straight line segments of the
threads between courses with the fabric held in an
extended (but not deformed) condition. The direction of
the spaced apart rows is the direction that the straight
line portions of the threads travel in proceeding between
successive courses. In warp knitting, these straight line
segments are often referred to as the "floats" of the
stitches. To illustrate the determination, Figure 3 shows
an intersection between vertical floats 10 of chain
stitches falling along the longitudinal axis (MD) of a
fabric of the invention and floats 20 of the second
thread system of that fabric. The float and reinforcing
directions coincide with each other. The angles formed
between the two directions of floats are "a" and "b" and
the angle that the floats make with the transverse
11
CA 02025126 2000-02-03
direction (TD) is "c". The present invention requires
that the angle between between the directions the two
thread systems be greater than 50 degrees. Thus, the
angle "a" and "b" each must be greater than 500. As
shown in this illustration, the angles are calculated in
degrees by the relationships:
a = 90 - c
b = 90 + c
c = tan-1 (L/nS)
wherein
L is the spacing between successive courses of
stitches (or the reciprocal of the number of stitches per
unit length in the fabric direction inserted by the
machine),
S is the spacing between rows of stitches is (equal
to the needle spacing, or reciprocal of the gage of the
multi-needle stitching machine), and
n is the number of needle spaces traversed by the
second thread system in proceeding between successive
courses.
EXAMPLES
The following examples illustrate the
preparation of multi-needle stitched nonwoven fabrics in
accordance with the invention and compare them to similar
multi-needle stitched nonwoven fabrics which are outside
the invention. In the Examples, samples of the invention
are designated with Arabic numerals; comparison samples
have an upper case letter in their designations.
Several types of fibrous starting layers are
used to prepare the fabrics described in each example.
The fibrous layers range from the weakest and least
durable wood-pulp paper of Example 1 which falls apart
when soaked in water, to the fairly strong and durable,
but not washable and launderable, point-bonded web of a
blend of staple fibers of Example 5. Further specific
details of the fibrous layers are given in each example.
12
CA 02025126 2000-02-03
In the examples, all the stitched samples and
comparisons, bulkable threads were multi-needle stitched
with a stitch frequency of 11.5 stitches per inch (4.5
per cm) in the first or longitudinal direction (also
called "machine direction" or "MD"). In samples and
comparisons that were also stitched in a second
direction, substantially inextensible threads and a
"gage" of 14 stitches per inch (5.5 per centimeter) were
employed. The bulkable threads were stitched in a chain
stitch and the substantially inextensible threads were
"laid-in" stitches or "tricot" stitches with floats
traversing one or two or four needle spaces. In the
summary tables of the examples, the following
designations were used to identify the particular thread
systems and stitch patterns.
Thread systems:
I-0. An inextensible, 40-den (44-dtex), 34-filament
flat nylon thread.
Y-1. A bulkable, 40-den (44-dtex), 13 filament,
textured nylon knitting yarn.
Y-2. A bulkable, 20-den (22-dtex) spandex filament
wrapped with 40-den (44-dtex) nylon.
I-1. Same as Y-1, but in extended and substantially
inextensible state when stitched.
I-2. Same as V-2, but in extended and substantially
inextensible state when stitched.
Stitch patterns:
P. Pillar stitch (or chain stitch)
T-1. Closed Tricot or 1 and 1 lap, 1-0,1-2
T-2. Closed 2 and 1 lap, 1-0,2-3
T-3. Closed 4 and 1 lap, 1-0,4-5
L-1. "1-across" inlay (0-0,2-2)
L-2. "2-across" inlay (0-0,3-3)
L-3. "4-across" inlay (0-0,5-5)
For each example, a summary table identifies
for each sample of the invention and each comparison
sample
13
CA 02025126 2000-02-03
and reports stitching threads and stitch patterns that
were used to construct the sample and the percent area
gather and minimum angle (a or b of Fig. 3, whichever is
smaller) between the reinforcing directions. Each table
also reports the measured wet and dry grab strength, hand
splittablity, and washability of each sample.
EXAMPLE 1.
In this example, two nonwoven fabrics of the
invention are made from a fibrous layer of pure pine wood
paper pulp containing no binder resins and nominally
weighing 1.2 oz/yd2 (40.7 g/m2). The samples of the
invention (1-1 and 1-2) are stitchbonded with a two
thread system, one of which supplies bulkable thread.
The stitchbonded samples are compared to the fibrous
layer without stitching (A-1) and with stitchbonding that
is outside the invention (A-2, A-3). This example
demonstrates the extraordinary strength that is added to
ordinary paper (that usually falls apart when simply
i~ersed in water) after it has been stitchbonded in
accordance with the invention. Samples 1-1 and 1-2 of
the invention are highly suited for use as wet or dry
wipe-cloths. Table 1 below summarizes the preparation of
the samples and their resultant properties.
A-1 through A-3 are comparison samples which
lack adequate stitching to stabilize the fabric in
accordance with the invention. The 1-across tricot
stitching is made with an angle of 39o between the
threads of the two directions (i.e., angle alpha between
the longitudinal direction of the row of chain stitches
with their vertical floats and the float of the tricot
stitches, as illustrated in Figure 1). The 2-across
stitching is made with an angle of 590 and the 4-across,
with an angle of 730. Results of the testing are
reported in Table 1.
14
CA 02025126 2000-02-03
Table 1 - Exam_p le 1
Sample A-1 Ai2 ~ ~ 1-22
Fabric Weight,
oz/yd2 1.39 1.73 2.12 2.06 2.04
g/m2 47.1 58.6 71.9 69.8 69.2
First Thread System None Y-1 Y-1 Y-1 Y-2
Pattern -- P p p p
Second Thread System None None I-0 I-0 I-2
Pattern -- -- L-1 L-2 T-3
Minimum Angle,
degrees -- -- 39 59 73
Grab Strength, as made
Dry MD, lb force 13.3 55.0 23.7 25.3 25.4
Newtons 59 245 105 113 113
Dry TD, lb force 8.5 2.5 19.6 28.8 29.4
Newtons 38 11 87 128 131
Wet MD, lb force 0.5 37.4 16.4 19.2 23.6
Newtons 2.2 16.6 77 85 105
Wet TD, lb force 0 0 15.8 28.2 29.2
Newtons 0 0 70 125 130
Hand Split Test
Wet FAIL FAIL FAIL PASS PASS
Dry FAIL FAIL FAIL PASS PASS
The superior strength ex hibited by samples
the
stitchbonded according to the invention the
versus
comparison samples, is evident from d grab
the reporte
strengths and hand-splittability results. The comparison
samples failed the splittability test: both
fabrics of
the invention passed. All samples ashability
failed the w
test. The short, loose fibers of the unbonded fibrous
starting layer are believed to be the source the
of
failures. However, samples 1-1 a nd 1-2 of the invention
still made very good reusable dry or wet wipes.
EXAMPLE 2
This example illustrates preparation f nonwoven
o
fabric by multi-needle stitching a fibrous starting
layer
CA 02025126 2000-02-03
in the form of a reinforced paper of 1.2 oz/yd2 (40.7
g/m2) made from a mixture of 75 weight % paper pulp and
25% 1.35-den (1.5-dtex), 0.5-inch (1.27-cm) long fibers
of polyethylene terephthalate. The construction and
measured properties of the samples are summarized in
Table 2 below. In contrast to the strength and
washability of the samples of the invention 2-1, 2-2 and
2-3, all comparison samples failed to survive more than
five washing cycles tests and all failed the hand
splittability test. Note that comparison sample B-1 had
no stitchbonding threads and B-2 and B-3 each had only
one yarn system.
EXAMPLE 3.
This example describes preparation of two
stitchbonded samples of the invention (3-1 and 3-2) from
a fibrous layer which is a 1.9 oz/yd2 (64.4 g/m2),
spunlaced, two-layer reinforced paper, one layer being of
pine wood paper pulp and amounting to 60 % of the
composite weight and the other layer being of 1.35-den
(1.5-dtex), 7/8-inch (2.2-cm) long fibers of polyethylene
terephthalate and amounting to 40% of the composite
weight. Four comparison samples were also made with the
same fibrous layer: C-1 having no stitchbonding; C-2 and
C-3 each having but one stitchbonding thread system: and
C-4 having two thread systems, one bulkable and one
inextensible, a minimum angle between the reinforcing
directions of only 39 degrees (versus at least 50 degrees
according to the invention). Table 3 summarizes the
sample constructions and shows how very well the fabrics
of the invention withstand repeated wash cycles, - more
than 75 washes for samples of the invention versus fewer
than 2 for comparison samples.
16
CA 02025126 2000-02-03
Table 2 -
Example
2
Sample B-1 ~ ~-3 ~ 2-22
Fabric Weight,
oz/yd2 1.23 1.65 2.0 2.1 2.1 2.1
g/m 41.7 55.9 67.8 71.2 71.2 71.2
First Thread none Y-1 none Y-1 Y-1 Y-1
Pattern -- p -- p p p
Second Thread none none I-1 I-0 I-0 I-2
Pattern -- -- T-1 T-2 L-3 T-3
Minimum angle -- -- -- 59 73 73
% Area Gather SD* 9 11 13 17 65
Grab Strengths
As made
Dry MD, lbs 6.3 23.2 25.1 30.6 25.1 25.1
Newtons 28 103 112 136 112 112
Dry TD, lb 5.4 1.6 3.2 20.4 33.8 24.0
N 24 7 14 91 150 107
Wet MD, lb 3.3 18.1 22.1 29.5 24.4 21.8
N 15 81 98 131 109 97
Wet TD, lb 3.2 1.1 2.6 20.8 28.6 32.5
N 14 5 12 93 127 127
After 1 wash
Dry MD, lb 5.0 18.3 23.5 35.7 22.3 24.3
N 22 81 105 159 99 109
Dry TD, lb 3.2 2.5 11.1 35.8 29.8 43.5
N 14 11 49 159 133 194
Wet MD, lb 3.5 16.6 19.9 35.8 20.4 20.2
N 16 74 89 159 91 90
Wet TD, lb 2.4 1.4 4.4 26.9 28.5 32.5
N 11 6 20 120 127 145
After 5 washes
Dry MD, lb FW* FW 23.0 37.8 18.1 23.2
N FW FW 102 168 81 103
Dry TD, lb FW FW 5.8 36.2 39.3 39.8
- N FW FW 26 161 175 177
Wet MD, lb FW FW 16.6 37.4 15.0 24.1
N FW FW 74 166 67 107
Wet TD, lb FW FW 7.6 28.3 22.6 37.3
N FW FW 34 126 101 166
Hand Split Test
Wet Fail Fail Fail Pass Pass Pass
Dry Fail Fail Fail Pass Pass Pass
Number of Washes
until failure 1 1-2 5 55 75+ 75+
* otes : SD = Samp le deteriorated in ter.
wa
FW = Failed test.
wash
17
CA 02025126 2000-02-03
Table 3 - Example
3
Sample C-~ ~ C-3 ~ 4 3-1 3-2
Fabric Weight,
oz/yd2 1.9 2.2 2.3 2.6 2.4 2.4
g/m2 64 76 78 88 81 81
First Thread none Y-1 none Y-1 Y-1 Y-2
Pattern -- p -- p p p
Second Thread none none I-1 I-0 I-0 I-2
Pattern -- -- T-1 L-1 T-2 T-3
Minimum angle -- -- -- 39 59 73
% Area Gather -- 20 17 12 19 69
Grab Strengths
As made
Dry MD, lbs 37.2 39.9 39.4 70.5 43.0 34.9
Newtons 166 177 175 314 191 155
Dry TD, lb 20.1 7.3 10.2 8.4 41.0 39.0
N 89 32 45 37 182 174
Wet MD, lb 32.1 32.7 32.3 75.9 34.8 30.0
N 143 146 144 338 155 134
Wet TD, lb 16.2 6.5 9.8 11.3 33.0 33.8
N 72 29 44 50 147 150
After 1 wash
Dry MD, lb FW FW 33.2 FW 35.6 38.2
N FW FW 148 FW 158 176
Dry TD, lb FW FW 6.5 FW 41.7 33.5
N FW FW 29 FW 186 149
Wet MD, lb FW FW 22.7 FW 32.3 45.4
N FW FW 101 FW 144 202
Wet TD, lb FW FW 5.4 FW 34.9 28.1
N FW FW 24 FW 155 125
After 5 washes
Dry MD, lb FW FW FW FW 37.6 43.1
N FW FW FW FW 167 192
.
Dry TD, lb FW FW FW FW 41.0 33.9
N FW FW FW FW 182 151
Wet MD, lb FW FW FW FW 28.9 58.3
N FW FW FW FW 129 259
Wet TD, lb FW FW FW FW 35.7 28.1
N FW FW FW FW 159 125
Hand Split Test
Wet Fail Fail Fail Pass Pass Pass
Dry Fail Fail Fail Pass Pass Pass
Number of Washes
until failure 0 0 2 1 75+ 75+
ote -- - not or inapplicable.
measured
See or othernotes. .
Table
2 f
18
CA 02025126 2000-02-03
EXAMPLE 4.
In this example two stitchbonded samples of the
invention (4-1 and 4-2) are prepared with two yarn
systems and a 1.2-oz/yd2 (40.7-g/m2) lightly spunlaced
web of 7/8-inch (2.2-cm) long, 1.35-den (1.5-dtex)fibers
of polyethylene terephthalate. Three comparison samples
are also prepared with the same fibrous layer: D-1 which
has no stitching; samples D-2 which is stitched with only
one yarn system: and D-3 which is stitched with two
thread systems that do not provide the minimum angle
between between the reinforcing directions of the
stitching. Table 4, below, which summarizes the sample
constructions and measured characteristics, again
demonstrates the advantages in strength and repeated
washability of the stitchbonded fabrics of the invention
over comparison samples.
EXAMPLE 5
This example illustrates the advantages of the
invention with stitchbonded fibrous layer which is
point-bonded carded web. The web is formed from a blend
of 75 weight percent of 1.5-inch (3.8-cm) long, 1.5-den
(1.7-dtex) acrylic fibers and 25 % of 3-inch (7.6-cm)
long, 3-den (3.3-dtex) polyester fibers of lower melting
temperature than the acrylic fibers. The web was point
bonded at 100 psi (689 kPa) and 160oC with a regular
pattern of 625 points per in2 (96.9/cm2), each point
having a diameter of 0.020 inch (0.05 mm). Two such
samples of the invention, 5-1 and 5-2, are compared with
three comparison samples. The comparisons are: E-1, the
point-bonded web without stitching: and E-2 and E-3,
which are each stitched with only one thread system.
Table 5, below, summarizes the construction and
properties of the samples and again shows the clear
advantages in strength, resistance to splitting and
repeated washability of the fabrics of the invention over
the comparison samples.
19
CA 02025126 2000-02-03
Table - Example .
4 4
Sample p~ p~ ~ 4~ 4-2
Fabric Weight,
oz/~d2 1.16 1.43 1.64 1.57 1.53
g/m 39.3 48.5 55.6 53.2 51.9
First Thread none Y-1 Y-1 Y-1 ~ Y-2
Pattern -- p p p p
Second Thread none none I-0 I-0 I-2
Pattern -- -- T-1 L-2 T-3
Minimum angle -- -- 39 59 73
% Area Gather -- 14 21 22 72
Grab Strengths
As made
Dry MD, lbs 24.6 29.5 25.3 28.4 64.8
Newtons 109 131 113 126 288
Dry TD, lb 11.3 4.0 12.9 14.2 22.4
N 50 18 57 63 100
Wet MD, lb 18.6 29.6 29.3 23.3 56.8
N 83 132 130 104 253
Wet TD, lb 10.5 6.9 11.6 14.4 22.6
N 47 31 52 64 101
After 1 wash
Dry MD, lb 20.5 22.9 FW 18.4 64.5
N 91 102 FW 82 287
Dry TD, lb 10.8 9.4 FW 12.6 38.2
N 48 42 FW 56 170
Wet MD, lb 18.6 21.7 FW 18.0 61.9
N 83 97 FW 80 275
Wet TD, lb 9.3 8.5 FW 12.0 33.5
N 41 38 FW 53 144
After 5 washes
Dry MD, lb 18.2 FW FW 19.3 68.3
N 81 FW FW 86 304
Dry TD, lb 11.0 FW FW 15.3 38.0
N 49 FW FW 68 169
Wet MD, lb 19.5 FW FW 19.9 62.0
N 87 FW FW 89 276
Wet TD, lb 9.2 FW FW 13.8 33.5
N 41 FW FW 61 149
Hand Split Test
Wet Fail Fail Fail Pass Pass
Dry Fail Fail Fail Pass Pass
Pass
Number of Washes
until failure 5 2 2 75+ 75+
ote Same in
as Table
3.
CA 02025126 2000-02-03
T able - Example 5
5
Sample ,~ ~-2 ~-3 5-1 5i2
Fabric Weight,
oz/yd2 2.1 2.4 2.5 2.7 2.6
g/m 71.2 81.4 84.8 91.5 88.1
First Thread none Y-1 none Y-1 Y-2
Pattern -- p -- p p
Second Thread none none I-0 I-0 I-2
Pattern -- -- T-1 L-3 T-3
Minimum angle -- -- -- 73 73
% Area Gather -- 14 10 18 64
Grab Strengths
As made
Dry MD, lbs 13.6 20.0 10.0 34.0 36.6
Newtons 61 89 89 151 163
Dry TD, lb 1.0 9.5 6.6 30.8 25.7
N 4.5 42 29 137 114
Wet MD, lb 12.8 19.1 15.1 29.1 32.8
N 57 85 67 137 114
Wet TD, lb 1.3 8.5 5.5 27.6 17.9
N 5.9 38 24 123 146
After 1 wash
Dry MD, lb FW FW 15.4 33.4 43.2
N FW FW 69 149 192
Dry TD, lb FW FW 9.1 35.7 37.3
N FW FW 40 159 166
Wet MD, lb FW FW 14.7 26.3 45.1
N FW FW 65 117 201
Wet TD, lb FW FW 9.2 30.6 35.4
N FW FW 41 136 158
After 5 washes
Dry MD, lb FW FW FW 33.0 45.2
N FW FW FW 147 201
Dry TD, lb FW FW FW 37.0 37.1
N FW FW FW 165 165
Wet MD, lb FW FW FW 31.3 43.1
N FW FW FW 139 192
Wet TD, lb FW FW FW 26.3 38.2
N FW FW FW 117 170
Hand Split Test
Wet fail fail fail pass pass
Dry fail fail fail pass pass
Number of Washes
until failure 0 0 2 60 75+
Notes: Same as in
Table
3.
21
