Note: Descriptions are shown in the official language in which they were submitted.
~ 61293-168
KNITTED FABRIC HAVING IMPROVED ELECTRICAL
C RGE DISSIPATION AND ABSORPTION PROPERTIES
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a new and improved knitted
fabric having improved electrical charge dissipation, absorption,
stain resistance, anti-pilling and ]inting and tensile strength
properties. More specifically, this invention relates to a
readily manufactured knitted fabric comprised of nonconductive
yarn that extends along the wale and combined with conductive
fibers that form overlaps and underlaps within the nonconductive
knit to such an extent so as to form a combined stitch construc-
tion, e.g., a modified "Queen's Cord" construction, providing an
electrically conductive matrix capable of quickly dissipating
charge along any direction of both the course and wale. Still
further, the invention's construction provides increased absorp-
tion, stain resistance and tensile strength properties, and mini-
mizes pilling and linting.
2. Description of the Prior Art
Electrostatic charge accumulates on clothing as the
wearer moves his or her arms and legs and as he or she walks on
nonconductive floor surfaces. The accumulation of such static
charge creates a problem in tight-fitting garments such a hosiery
and sporting apparel in which static charge causes adjacent
garments to cling to one another. This static cling causes both
discomfort for the wearer and unpleasant shocks. Such charge
accumulation can also pose significant problems when the wearer
~' ~
12~ 6
61293-168
works in an environment in which any static charge is undesirable
or dangerous. A need exists, therefore, for a means to control
electrostatic charge accumulation on fabric,
- la -
12C3~ 6
1 particularly fabric used in clothing worn by individuals who
2 occupy or handle materials in areas in which an electrostatic
3 discharge can be hazardous to the individual or can damage
4 material which is being handled by the wearer, e.g., in hospital
environments where potentially explosive gases are present and
6 patient comfort is important, or in "clean rooms" where
7 electrically sensitive microcircuits are manufactured.
8 Still further, those environments, particularly
9 hospitals, in which the control of electrostatic charge
accumulation is important require a fabric, including
11 particularly a towel, that can provide a multitude of functions
12 and uses. In addition to control of electrostatic discharge,
13 improved absorbancy, stain resistance and tensile strength, as
14 well as minimized pilling and linting, are important
~5 characteristics for fabrics used in hospital environments. The
16 advantages of use of this invention in other environments are
17 also evident.
18 The utilization of fibers possessing electrical
19 1 conductivity (e.g., metal fibers, fibers coated with electrically
1 conductive ~aterial, or metal laminate filaments) in combination
21 ~ with common natural and manmade fibers to produce a woven,
22 knitted, netted, tufted, or otherwise fabricated structure, which
23 ~ readily dissipates static charge as it is generated is well
24 , known.
~l In U.S. Patent 3,823,035, issued to Sanders, an
26 ' electrically-conductive texti~e fiber is disclosed in which
2~ finely-divided electrically conductive particles are uniformly
28 suffused in a filamentary polymer substrate. Sanders discloses
29 the interweaving of such electrically conductive fibers with
ordinary threads made from natural fibers such as cotton or wool
-2-
1;~ 6
1 in an amount sufficient to render the electrical resistance of
2 the fabric to a value of 109 ohms/cm.
3 U.S. Patent 4,312,913, issued to Rheaume,
J discloses a heat-conductive woven fabric comprising a plurality
of fill layers of weavable yarns, each yarn comprising a
6 plurality of fibers that are metallic or are coated with an
7 effective amount of a metallic, heat conducting material. An
8 angle weave pattern is woven through the layers of fill yarns in
9 Rheaume, and this angle woven pattern extends from the top to the
bottom of several layers of fill yarns.
11 Similarly, U.S. Patent 4,296,855, issued to
12 Blalock, also discloses a woven pattern of filler and warp yarns
13 comprised of an electrically insulating material suffused with
14 electrically conducting carbon particles, the warp and filler
being woven in an open mesh configuration.
16 U.S. Patent 4,422,483, issued to Zins, discloses
17 a multiplicity of elongated filaments which are essentially
18 parallel to each other and which form a single ply of a
19 I conductive thread for woven fabrics. The elongated filaments in
I Zins are non-textured continuous, non-conductive filaments or
21 , warp threads which are combined together with conductive
22 filaments or fill threads to form a conductive woven fabric.
23 Neither Sanders, Rheaume, Blalock or Zins
24 disclose a conductive knitted fabric. While U.S. Patent
4,443,515, issued to Atlas, and its divisional 4,484,926,
26 disclose that conductive fibers comprised of synthetic polymers
27 may be incorporated into knitted fabrics, those references do not
28 disclose a pattern whereby such conductive fibers can be
29 economically incorporated into a Xnitted fabric so as to
dissipate static electricity in any direction along the course
-3-
~2~ 6
l and wale directions of the fabric. Nor do they have the
2 special combination of elements, including improved absorption,
3 stain resistances and tensile strength and minimized pilling and
~ linting, unique to this invention.
S U.S. Patent No. 4,398,277, issued to
6 Christiansen et al., does disclose a pattern whereby insulative
7 yarn and electrically conductive yarn are knitted together on two
8 levels. The insulative yarn in Christiansen et al. forms a
9 series of interlocking loops on both the technical face and back
of the fabric in a tricot construction, while the electrically
11 conductive yarn forms a series of chain stitches on only the
12 technical face. Christiansen et al. disclose that when their
13 fabric is knitted in such a two layer construction, one of the
14 surfaces (i.e., the technicaI face) will be relatively
nonconductive. Electrical charge dissipation in such a
16 construction, therefors, is limited to the wale direction of the
17 technical face of the fabric.
18 Attempts have been made to develop a knitware
19 pattern that can be economically manufactured, which require the
use of a relatively small amount of conductive fiber and which
21 possess electrical conductivity along both the course and wale
22 directions and on both the technical face and back of a two layer
23 knitted fabric. A knitted fabric in which conductive yarn is
24 knitted in an argyle pattern together with nonconductive yarn,
resulting in a fabric having electrical conductivity along the
26 course and wale directions on both the technical face and back,
27 has been constructed.
28 The argyle construction suffers from several
29 disadvantages. Such a construction requires that the conductive
~0 fiber be stitched simultaneously along both the course and wale
~6~6
1 directions to form a saw-tooth pattern known as an "Atlas stitch"
2 which, when joined to a similar adjacent stitch, forms the arg~;le
3 pattern. Such simultaneous horizontal and vertical movement of
4 fiber requires that the argyle knit be manufactured on a knitting
machine having at least two separate guidebars dedicated to the
6 argyle construction. Further, the argyle construction requires
7 the use of a substantial amount of conductive yarn, which is a
8 significant disadvantage given that such yarn is currently more
9 than about thirty-six times as expensive as nonconductive yarn.
An additional significant disadvantage of this conductive argyle
ll construction is that it can only be fabricated by a relatively
12 complex warp knitting machine, i.e., one having two or more
13 dedicated guidebars as mentioned above.
14 A need exists, therefore, for a relatively
inexpensive easily knitted fabric capable of rapidly and
16 effectively discharging static electricity. Further, the need
17 exists for such a knitted fabric which is capable of discharging
18 static electricity along the course and the wale directions of
19 ¦ the fabric and on the technical back and/or face of the fabric.
' Further, there is also a need for such an antistatic knitted
21 j fabric that can be manufactured on a conventional knitting
22 machine that is not as mechanically complex as those required for
23 complex knits, e.g., double argyle, presently used in the
24 industry.
Still further, those environments, particularly
26 hospitals, in which the control of electrostatic charge
27 accumulation is important, require a fabric, including
28 particularly a towel, that can provide a multitude of functions
29 and uses. In addition to control of electrostatic discharge,
improved absorbancy, stain resistance and tensile strength, as
1 well as minimized pilling and linting, are important
2 characteristics for fabric, including particularly a to~el, use~
3 in hospital environments. The advantages of use of this
~ invention in other environments, and in other shapes an~ forms,
are also evident.
6 Accordingly, it is an object of the present
7 invention to provide a knitted fabric, including particularly a
8 towel, having improved electrical charge dissipation, absorption,
9 stain resistance, anti-pilling and linting and tensile strength
properties.
11 It is a further object of the present invention
.2 to provide such a knitted fabric in which an electrostatic charge
,3 can be dissipated both along the course direction of the knitted
14 fabric and the wale direction of the knitted fabric on the
technical back and/or face.
16 It is a further object of the present invention
17 to provide a knitted fabric having improved electrical discharge
18 dissipation, absorption, stain resistance, anti-pilling and
19 ¦ linting and tensile strength properties in which the percentage
of conductive fiber employed in the fabric is significantly less
21 than that required in knitware construction disclosed in the
22 prior art.
23 It is a still further object of the present
24 ~ invention to provide a knitted fabric that can be manufactured on
~ a conventional knitting machine that is mechanically less complex
26 than those machines presently used to manufacture conductive
27 knitware, i.e., one that requires the use of only one dedicated
28 guidebar.
29 Other objects and advantages will be in part
evident and in part hereinafter pointed out.
~'~9f~1~96
In accordance with the present invention there is provided a
knitted fabric having improved electrical charge dissipation,
absorption, stain resistance, anti-pilling and linting, and
tensile strength properties comprised of stitches of nonconductive
fibers knitted together with the conductive fiber that form
underlaps and or overlaps in combination with nonconductive fiber
in the directions both the course and the wale, the conductive and
absorbant fibers being substantially parallel and perpendicular to
the wale of the fabric, so as to the form an electrically
conductive matrix capable of dissipating charge in substantially
any direction along the course and wale of the fabric.
In accordance with the present invention there is also
provided a knitted fabric having improved electrical charge
dissipation, absorption, stain resistance, anti-pilling and
linting, and tensile strength properties, and a modified "Queen's
Cord" construction fabricated by threading full the bottom bar of
an 84 inch Mayer model KC3, 3 bar, 20 gauge warp knit tricot
knitting machine with 150 denier texture polyester stitched 4S-10,
the middle bar of the machine being threaded 6 ends out and one
end in with 70 denier textured polyester plied with 2 ends per
thread of BASF conductive nylon and stitched in the following
sequence:
10-10-01-10-01-10-01-10-78-78-87-78-87-78-87-78,
and with an intermediate let off set up for the middle bar on a
ratio of 1.21 and with a chain sequence of:
- 7a -
~2~ 6
000(6X444)000-000(6X444)000,
and with an intermediate let off set up for the middle bar on a
ratio of 1.21 with a chain sequence of:
000(6X444)000-000(6X444)000,
and with a top bar threaded 6 ends in and end out with 150 denier
textured polyester stitched 10-01.
In accordance with the present invention there is also
provided a method of manufacturing a knitted fabric having
improved electrical charge dissipation, absorption, stain
resistance, anti-pilling and linting and tensile strength
properties comprised of knitting stitches of nonconductive fiber
together with conductive fibers, the conductive fibers forming
overlaps and/or underlaps with the nonconductive fibers along
both the course and the wale directions, the conductive fibers
being parallel or perpendicular to the wale of the fabric, thereby
forming an electrically conductive matrix capable of dissipating
charge in substantially any direction along the course and wale of
the technical faced and back of the fabric.
According to an aspect of the present invention there is also
provided a method of manufacturing a knitted fabric having
improved electrical charge dissipation, absorption, stain
resistance, anti-pilling and linting and tensile strength
properties, and a modified Queenls Cord construction comprising:
(a) threading full the bottom bar of an 84 inch Mayer model
KC3, 3 bar, 20 gauge warp knit tricot knitting machine with 150
denier textured polyester stitched 45-10;
(b) threading the middle bar of the machine 6 ends out and
- 7b -
lZ5~61~6
one end in with 70 denier textured polyester plied with 2 ends per
thread of BASF conductive nylon and stitched in the following
sequence:
10-10-01-10-01-10-01-10-78-78-87-78-87-78-87-78;
(c) setting up an intermediate let off for the middle bar of
the machine in a ratio of 1.21 with a chain sequence of:
000(6X444)000-000(6X444)000;
(d) threading the top bar of the machine 6 ends in and one
end out with 150 denier textured polyester stitched 10-01.
According to an aspect of the present invention there is also
provided a towel having improved electrical charge dissipation,
absorption, stain resistance, anti-pilling and linting, and
tensile strength properties comprised of stitches of nonconductive
fibers knitted together with the conductive fiber that form
underlaps and or overlaps in combination with nonconductive fiber
in the directions both the course and the wale, the conductive and
absorbent fibers being substantially parallel and perpendicular t
the wale of the fabric, so as to the form an electrically
conductive matrix capable of dissipating charge in substantially
any direction along the course and wale of the fabric.
According to an aspect of the present invention there is also
provided a method of manufacturing a towel having improved
electrical charge dissipation, absorption, stain resistance, anti-
pilling and linting and tensile strength properties comprised of
knitting stitches of nonconductive fiber together with conductive
fibers, the conductive fibers forming overlaps and/or underlaps
with the nonconductive fibers along both the course and the wale
- 7c -
1.'2g~6
directions, the conductive fibers being parallel or perpendicular
to the wale of the fabric, thereby forming an electrically
conductive matrix capable of dissipating charge in substantially
any direction along the course and wale of the technical face and
back of the towel.
According to an aspect of the present invention there is also
provided a method of manufacturing a towel, having improved
electrical charge dissipation, absorption, stain resistance, anti-
pilling and linting and tensile strength properties, and a
modified Queen's Cord construction comprising:
(a) threading full the bottom bar of an 84 inch Mayer model
KC3, 3 bar, 20 gauge warp knit tricot knitting machine with 150
denier textured polyester stitched 45-10;
(b) threading the middle bar of the machine 6 ends out and
one end in with 70 denier textured polyester plied with 2 ends per
thread of BASF conductive nylon and stitched in the following
sequence:
10-10-01-10-01-10-01-10-78-78-87-78-87-78-87-78;
(c) setting up an intermediate let off for the middle bar of
the machine in a ratio of 1.21 with a chain sequence of:
000(6X444)000-000(6X444)000;
(d) threading the top bar of the machine 6 ends in and 1 end
out with 150 denier textured polyester stitched 10-01;
(e) trim~ing the fabric into the shape of a towel having the
dimensions of 18" x 33";
- 7d -
12~6196~
(f) finishing the edged of the fabric so that it does not
unravel in normal wear-and -tear. e.g. with a pearl edge folded,
small turn edge, plain serged edge, or by any other means common
in the art;
(g) squaring the corners of the fabric by sewing or by any
other means common in the art.
~ 2~ 36
61293-168
BRIEF DESCRIPTiON_OF THE DRAWING
FIG~ 1 is a lapping diagram which depicts the stitch
formation of the conductive stitch of the present invention.
FIG. 2 depicts an enlarged section of the conductive
stitch, shown in Fig. 1. This FIG. 2 illustrates the arrangement
of the stitches of conductive fiber 1 extending along the course
and wale directions and which forms overlaps and underlaps within
a nonconductive knit (not shown) so as to form the preferred modi-
fied Queen's Cord construction.
DETAILED DESCRIPTION
Referring to FIG. 1 and FIG. 2, the illustrated sequence
of chain stitches may be formed on a knitting machine of the type
well known in the art. See, e.g., "An Introduction the Stitch
Formations in Warp Knitting" ~1.3, pp. 27-42 (Employees Assoc.
Karl Mayer E.V., West Germany 1966) (hereinafter "Stitch
Formations"). A significant advantage of the present invention is
that a knitting machine containing only one dedicated guide bar
may be employed to fabricate the desired pattern of stitches of
nonconductive fiber interlaced with conductive fiber 1.
As illustrated in FIG. 2, the dissipation of electrical
charge along both the course and wale directions, as well as
improved absorption, stain resistance, anti-pilling and linting
and tensile strength properties, are ensured by the novel tech-
nique of forming underlaps and/or overlaps with the conductive
fiber 1 within a nonconductive knit fabric along both the course
and wale directions. This connection of conductive fiber 1 with
adjacent nonconductive fibers results in a combined stitch
construction, e.g., a modified "Queen's Cord"
- 8 -
31 Z~ 6
1 construction, that is electrically conductive along both the
7 course and wale directions, and, when a two layered knit is
3 fabricated, on both the technical face and back of the fabric.
~ This modified "Queen's Cord" construction differs from known ~nit
constructions in that the conductive fibers extend either along
6 the course of the fabric or wale of the fabric, unlike the
7 aforementioned argyle pattern in which the conductive fiber
8 extends in a diagonal along the course or wale. "Stitch
9 Formations", at p. 104, Fig. 155, depicts a "Queen's Cord"
construction which is to be contrasted with the preferred
11 embodiment of the present invention. It is an important feature
12 of the present invention that the conductive fibers 1 form under
13 and/or overlaps within the nonconductive fabric along the course
14 and wale directions to such an extent that a conductive matrix is
formed in which charge can be dissipated along any number of
16 pathways in the course or wale direction of the technical face
17 and back of the fabric.
18 It is also an important feature of the present
19 l invention that the combined stitch construction, e.g., a modified
, "Queen's Cord" construction, provides absorption characteristics.
21 I Still further, the invention demonstrates improved stain
22 resistance and tensile strength, as well as minimizes pilling and
23 linting.
24 In an alternative embodiment useful, é.g., as an
antistatic wall covering, a knitted fabric can be constructed in
26 accordance with the methods of the present invention wherein the
27 conductive fiber is trapped between the overlaps and underlaps of
28 the nonconductive knitted fabric as seen from the technical back.
29 The conductive fiber 1 can be selected from any
of the number of types of conductive fibers commercially
J ~ 6
l available, some of which have been considered in the preceding
2 discussion of the prior art. These conductive fibers can consist
3 either of singular yarns or be plied with other yarns where extra
4 fabric strength or workability is desired.
EXAMPLE I
6 An example of the electrically conductive and
7 absorbant knitted fabric of the present invention, in the form of
8 a towel, was constructed as follows. The bottom bar of an 84
9 inch Mayer model KC3, 3 bar, 20 gauge warp knit tricot knitting
7 0 machine was threaded full with 150 denier textured polyester and
ll stitched 45-10. (Idler links for the 3 link per course set-up
12 were omitted in this Example.) The middle bar of the machine was
13 threaded 6 ends out and one end in with 70 denier textured
14 polyester plied with 2 ends-per thread of BASF conductive nylon
and stitched in the following sequence:
16 10-10-01-10-01-10-01-10-78-78-87-78-87-78-87-78.
17 An intermediate let off was set up for the
18 middle bar on a ratio of 1.21 with a chain sequence as follows:
19 1 OOO(~X444)000-000(6X444)000.
~I The top bar was threaded 6 ends in and 1 end out
21 ,¦ with 150 denier textured polyester and stitched 10-01. The
22 , knitted fabric so constructed was jet dyed and framed 72 inches
23 ~ wide and slit into 4 separate 18 inch strips. The runner lengths
24 , for this fabric were:
top bar: 80 inches per rack
26 middle bar: 96 inches per rack
27 j bottom bar: 148 inches per rack
28 ' The fabric quality pull was 17 inches per rack.
29 The total inches for an 84 inch panel by bar were as follows:
top bar: 2,280 ends
--10--
96
1 middle bar: 480 ends
2 bottom bar: 3,360 ends
3 The fabric was cut into the form of a towel
~ having dimensions of 18" x 33", and the edges of the towel were
finished so that the edges do not unravel in normal wear-and-
tear, e.g. with a pearly edge folded small torn edge, a plain
7 serged edge, or by any other means common in the art. The
8 corners of the towel were then squared and sewn.
g The electrical charge dissipation characteristic
1~ of a fabric constructed, in the form of a towel, in accordance
11 with the present invention was tested and is set forth in Example
12 2.
13 The absorbancy characteristic of a fabric
14 constructed, in the form of a towel, in accordance with the
present invention was also tested and is set forth in Example 3.
16 The anti-pilling and linting characteristic of a
17 fabric constructed, in the orm of a towel, in accordance with
18 the present invention was also tested and is set forth in Example
19 1 4
1 The stain resistance characteristic of a fabric
21 constructed, in the form of a towel, in accordance with the
22 present invention was also tested and is set forth in Example 5.
23 Still further, the tensile strength
24 characteristic of a fabric constructed, in the form of a towel,
in accordance with the present invention was tested and is set
26 set forth in Example 6.
27 EXAMPLE 2
28 A sample of antistatic and absorbant fabric, in
29 the form of a towel, and fabricated in accordance with the
Example 1 was tested for effective surface resistivity and charge
lZg~6
1 to decay time in accordance with the methods recommended in
2 National Fire Protection Association ~NFPA) 99. The tests were
3 conducted at a temperature of 23~C and a relative humidity of
4 50%. The fabric measured approximately 6 X 105 ohms/cm. in the
machine direction and 2 X 106 ohms/cm. in the crossmachine
6 direction. Decay times in both directions were much less than
7 0.01 seconds. The material, therefore, easily met the resistance
8 and decay specifications of National Fire Protection Association
9 (NFPA) Standard 99.
EXAMPLE 3
11 A sample of antistatic and absorbant fabric, in
12 the form of a towel, and fabricated in accordance with Example 1
13 was tested for absorbancy in accordance with the methods
14 recommended in American Association of Textile Chemists and
Colorists (AATCC) Standard 79-1986. The test procedure cycle was
16 composed of a 57-C reverse wheel wash, followed by a tumble dry,
17 15 minute autoclave cycle at 121C, and 15 pounds pressure.
18 After 1, 10 and 50 wash cycles, the fabric demonstrated immediate
19 il absorption. The material, therafore, easily met the absorbancy
j specifications of AATCC 79-1986. The significance of
21 ¦ demonstrated immediate absorption after even 50 washings is that
22 , the absorbancy derives from the construction of the fabric, is
23 integral in its construction, and is not a factor of any
24 particular finish placed on the fabric. It shouid further be
pointed out that polyester fabrics, while known for stain
26 resistance, anti-pilling and linting, and tensile strength
27 properties, are notoriously hydrophobic.
28 EXAMPLE 4
29 A sample of the antistatic and absorbant fabric,
in the form of a towel, and fabricated in accordance with Example
-12-
`~ 12~6~6
1 1 was tested for pilling and linting. After 1, 10 and 50 wash
2 cycles, a visual examination of the fabric demonstrated no
3 noticeable pilling and linting.
11
12
13
14
16
17
18
19
22
23
24
26
27
28
29
-13-
1 _XAMPLE 5
2 A sample of the antistatic and absorbant fabric,
3 in the form of a towel, and fabricated in accordance with Example
~ 1 was tested for stain resistance in accordance with the methods
recommended by an independent testing company. The test
6 procedure involved samples of the fabric that had been washed 1,
7 10 and 50 times, and then were stained with blood, iodine and
8 surgical jelly. One of each sample was then washed immediately,
g while another of each sample was allowed to sit undisturbed for
24 hours, after which it was washed. The residual stains, if
11 any, were then rated on a scale from much staining to negligible
12 or no staining. After testing, virtually every sample
13 demonstrated either slight, negligible or no staining.
14 EXAMPLE 6
A sample of the antistatic and absorbant fabric,
16 in the form of a~ towel, and fabricated in accordance with Example
17 1 was tested for tensile (breaking and tearing) strength in
18 accordance with the methods recommended in American Society for
19 ,I Testing and Materials (ASTM) D-1682 and ASTM D-2661. The tests
¦ were conducted at a temperature of 7'C and a relative humidity of
21 ¦ 65%. ASTM D-1682's grab method for testing breaking strength
22 yielded results, in lbs., of 122.6 for wales and 202.4 for
23 courses. ASTM D-2661's tongue tear method for testing tearing
24 strength yielded results, in lbs., of 9.0 for length and 14.4 for
I width. The material, therefore, easily met the breaking strength
26 and tearing strength specifications of ASTM D-1682 and ASTM D-
27 2661.
28 It should be understood that this invention's
29 improved electrical charge dissipation, absorption, stain
resistance, anti-pilling and linting, and tensile strength
-14-
1 characteristics interact to yield the sum of what is this
2 invention.
3 It should be further understood that this
4 invention is not limited to the illustrations described and shown
S herein, which are deemed to be merely illustrative of the best
6 modes of carrying out the invention. The invention also
, encompasses all such modifications which are within the scope of
9 the following claims.
11
12
13
14
16
17
18
19
21
22
23
24
26
27
28
29
-15-
