Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~LQ~
INTEGRAh, ELECTRICALLY-CONDUCTIVE ~EXTI~E FI~.~E~
This invention relates to textiles in general,
and in particular to an electrically-conductive textile flber
or use in the construction of antistatic fabrics of varlous
kinds.
The accumulation of static electricity as a result
of the utilization of ~abrics is a phenomenon which has
commanded the atten~ion of the textile industry for some
time. The presence of static is a cause not only of annoy-
ance -- (e.g. items of apparel cling to the body znd are
attracted to other garments; fine particles of lint and
dust are attractQd to upholstery fabrics, increasing the
frequency of required clea~ing; one experiences a jolt or
shoc~ upon touching a m~tal doorknob af~er wal~ing across
a carpet) -- but also of danger (eag. the discharge of static
elec~ricity can resul~ in spar~s capable or igniting 1am-
mable mixtures such as ether/air, which are commonlv four.d
in nospitals, especially in operating rooms). All of the-ce
effects are accentuated in atmospheres of low relative
humidi~y.
Of the many proposals for preven~ing the undesir-
able uildup of static electricity, the most satis~actory,
with r_~pect to their efficiency and permanencP, have appea~ed
to be those w~ich comprehend the utilization of fibers ~os-
sessing electxical conductivlty ~e.g. metal fibers; fi~ers
coated with ~lect_ically-conductive materlal; ibe~s contalnln~
~;
a657~
conductive, block copolymeric materials dispersed therein in
the form of long, slender particles; integral fibers having
a sheath or core containing electrically-conductive material;
and metallic laminate filaments) in combination with common
natural or man-made fibers to produce a woven, knitted,
netted, tufted, or otherwise fabricated structure, which
readily dissipates the static charges as they are generated.
Some of the more noteworthy of these methods and structures
may be found in U. S. patents 2,129,594; 2,714,569; 3,069,746;
3,288,175; 3,329,557; 3,582,444; 3,582,445; 3,582,448;
3,586,597; 3,590,570; 3,637,908; 3,639,502; 3,729,449; 3,803,453
and 3,823,035; in Webber, "Metal Fibers," Modern Textile
Magazine, May, 1966, pp. 72-75; in Belgian patents 775,935
and 790,254; and in French patent 2,116,106.
Notwithstanding the efficacy of these and similar
expedients, they are found lacking in certain important aspects,
viz:
The manufacture of metallic ~ibers of fine denier,
especially in the form of monofilaments, is a difficult ànd
costly operatiGn; and since such fibers are quite dissimilar
in character from ordinary textile fibers, problems arise in
connection with blending and processing, as well as in the
hand of the products obtained.
Metallic laminate filaments, on the other hand, do
not present blending and processing problems, because of
their close similarity to ordinary textile fibers, and the
hand of the products obtained is consequently not objectionable.
However, the cost of such filaments is high when compared with
the natural or man-made fibers with which they are blended.
Textile fiber substrates,the surfaces of which have
been coated by vapor deposition or electrodeposition, or by
the application of adhesive compositions containing inely
di~ided particles of electrically-conductive material, are
~Q~S~7~
in some cases less costly than metal fibers and/or metallic
laminate filaments, depending upon the nature of the elec-
- trically-conductive material employed and the coating method
chosen. However, such coatings are ofter found lacking in
cohesion and adhesion and are frequently too thick to be
practicable in some applications -- especially when the
nature of the electrically-conductive particulate matter is
such that a high concentration thereof is required for satis-
factory conductivity. Economy is generally achieved, there-
fore, only through sacrifices in durability of the conductivity
of the fiber.
The extrusion of powdered synthetic polymer/finely
divided electrically-conductive material blends directly
into filaments, or as distinct coatings on filamentary sub-
strates having the same or different polymeric compositions,
is also well known. ~nfortunately, these substantially
homogeneous blends require a high concentration of the elec-
trically-condustive material. They are generally not readily
extruded, if at all, and any filaments and filamentary coat-
ings which are produced therefrom have extremely poor cohesion
and adhesion, and are therefore completely lacking in durability.
Filamentary polymer structures containing conductive
polymeric materials (e.g. polyalkylene ether - polyamide block
copolymers), which are dispersed in the polymer substrate in
the form of long, slender particles or layers whose longitudinal
axes are substantially parallel to the direction of
molecular orientation of the filament, are difficultly ob-
tained in a reproducible form, thereby increasing their cost
and/or decreasing the ambit of their utility.
Al~hough they have been shown to provide ver~ bene-
ficial results in most applications, filamentary polymeric
structures having either an integral sheath or an integral
core comprising electrically-conductive material are somewhat
limited in their utility; viz., they are not suitable in
applications requiring a very low resistance.
Although multi-component filaments are known in
the art (see U. ~. patent No. 3,531,368, which discloses a
multi-component filament comprising a plurality of fine
filamentary parts which are continuous along the axis of
the filament), and although it is also old to modify one
of the components of a multi-component filamentary structure
by the introduction of additives such as anti-static agents,
including electrica~ly-conductive carbon black (see U. S.
patents 2,428,046 and 3,582,448), the present invention as
hereinbelow specified and hereinafter defined is not obvious
to one bf skill in the art, as only the particular combi-
nation of elements as recited herein will result in a filament
having properties which obviat~ the deficiencies of the prior
art as discussed hereinabove.
Accordingly, it is the primary object of this
invention to provide a low-cost, yet durable, electrically-
conductive iber which has reproducible conductive properties
over a wide range o~ conductiYities, substantially retains
the desirable physical properties of the unmodi~ied:polymeric
substrate, and presents no problems in the blending and pro-
cessing thereof with ordinary natural and man~made textile
fibers.
SU~ARY OF_THE INVENTION
This object -is achieved, and the disadvantages of
the prior art are obviated, by providing an integral
electrically-conductive textile filament which has a resistance
o~ not more than about 109 ohms/cm and comprises:
14;~aJ~
(a) from 2 to about lOG0 electrically-conducting,
longitudinally-directed strata of fiber-forming polymeric
material having finely-divided particles of electrically-
conductive carbon black uniformly dispersed therein, the con-
centration of electrically-conductive carbon black in each
electrically-conducting stratum being within the following limits:
(1) For 2 electrically-conducting strata:
from about 30 percent by weight -- at a total concentration
of carbon in the integral filament of about 1/2 percent by
weight -- to ahout 70 percent by weight -- at a total concen-
tration of carbon in the integral filament of about 1/4 percent
by weight; and
(2) For about 1000 electrically-conducting
strata: from about 30 percent by weight -- at a total concen-
tration of carbon in the integral filament of about 12 percent
by weight -- to about 70 percent by weight -- at a total
concentration of carbon in the integral filament of about
2 percent by weight; and
(b) in coe~tensive union with each electrically-
conducting stratum along the length of at least one major
surface thereof, a non-conducting stratum of the same fiber-
forming poly~eric material.
Moreover, it is especially advantageous if the
polymeric material is an acrylonitrile polymer having at
least about 85 percent by weight of acrylonitrile and up to
about 15 percent by weight of another polymerizable mono-
olefinic monomer copolymerizable therewith.
Furthermore, the integral, electrically-conductive
textile filament of the present invention is particularly
useful when there are 4 electrically-conducting, longitudinally-
directed s~rata o fiber-formin~ po~ymeric material, each
having ~inely-divided particles of alectrically-conductive
carbon black uniformly dispersed therein in a concentration
of 40 - 60 percent by weight, the total concentration of carbon
in the inteyral filament being between 4 and 6 percent by
weiaht.
7~
The production ~f integral, electrically-conductive
filaments according to the present invention is advantageousl~
accomplished by:
(1) providing a first stream of a solution of a
fiber-forming polymeric material;
(2) providing a second stream of the same solution
of the polymeric material, and dispersing in the second stream
the appropriate concentration of a ~inely-divided, electrically-
conductive carbon black, which does not dissolve in, or react
with the solvent;
(3) providing a third stream identical to the
first stream;
(~) providing a fourth stream identical to the
second stream; and
(5) causing the first, second, third, and fourth
streams to join in order into a composite stream without
appreciable mixing of the individual component streams thereof,
and spinning the resulting composite stream into integral
filaments.
In a preferred embodiment of this process, the
: first and second streams described above are introduced simul-
taneously into the inlet end of an interfacial surface generator
which generates between 8 and about 2000 total layers and the
resulting multi-layered composite stream is spun into integral
filaments by standard wet or dry spinning techniques.
In another preferred embodiment of this process, many
filaments are extruded in a tow, which is cut into staple and
subsequently handled by conventional methods to produce a
conductive spun yarn.
BRIEF DESCRIPTION OF THE DRAWTNG
.
For a more complete understanding of the present
invention, reference should be made to the detailed description
57~
of the preferred embodiments thereof, which is set fGrth below,
which description should be read together with the accompanying
drawing, wherein:
FIG. 1 and FIG. 2 are perspective views schematically
illustrating embodiments of an inteyral, electrically-con-
ductive filament according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The polymeric material comprising the integral,
electrically-conductive textile filament of the present
invention may be any of the well-known film or fiber-forming
polymers commonly employed in the art, such as acrylics,
acetates, modacrylics, cellulosics, polystyrenes, polyolefins,
polyesters, and polyamides. Acrylonitrile polymers having
at least about 85 percent by weight of acrylonitrile and up
to about 15 percent by weight of another polymerizable mono-
olefinic monomer copolymerizable therewith have been shown to
be especially advantageous. The unitary filament must comprise
at least two electrically-conducting, longitudinally-directed
strata of ~iber-forming polymeric material, each of which
has uniformly dispersed therein finely-divided particles of
an electrically-conductive carbon black. A particle size of
about 20 to 40 m~ is preferred.
The number of electrically-conductive strata and
the appropriate concentration of electrically-conductive
carbon black in the individual electrically-conductive
strata were determined empirically. In this regard, it was
desired that the electrical resistance of the unitary filament
be not more than about 109 ohms/cm, and for many applications,
between about 10- and 109 ohmsjcm. Under the latter conditions,
the unitary filament is eminently suitable for employment in
a wide variety of fabrics for preventing the accumulation of
hiyh charges of static electricity while presenting no
appreciable electrocution hazard.
7~
The filament of the present invention accordingly
has:
(a) from 2 to about 1000 electrically-conducting,
longitudinally-directed strata of fiber-forming polymeric
material having finely-divided particles of electrically-
conductive carbon black uniformly dispersed therein, the
concentration of electrically-conductive carbon black in each
electrically-conducting stratum being within the following
limits:
: 10 (1) For 2 electrically-conducting strata:
: from about 30 percent by weight -- at a total concentration
of carbon in the integral filament of about 1/2 percent by
weight -- to about 70 percent by weight -- at a total concentra-
tion of carbon in the integral filament of about 1/4 percent
by weight; and
(2) For about 1000 electrically-conducting
strata: from about 30 percent by weight -- at a total
: concentration of carbon in the integral filament of about
; 12 percent ~y weight -- to about 70 percent by weight --
at a total concentration of carbon in the integral filament
of about 2 percent by weight; and
'~ (b) in coextensive union with each electrically-
~ conducting stratum along the length of at least one major
: surface therof, a non-conducting stratum of the same ~ 25 fiber-forming pol~meric material.
: Furthermore, the integral, electrically-conductive
: textile filament of the present invention is particularly
useful when there are 4 electrically-conducting, longitudinally-
directed strata of fiber-forming polymeric material, each
having finely-di~ided particles of electrically-conductive
carbon black uniformly dispersed therein in a concentration
of ~0 - 60 percent by weight, the total concentration of
carbon in the integral filament being between 4 and 6
percPnt by wei~ht.
7(~
Referring to ~he drawing, although t~lo longitudinally-
directed electrically-conducting strata (12) are sufficient
to afford the combination of properties long sought after (see
FIG. 1), a larger number of electrically-conducting strata (12)
has been found particularly advantageous. (See FIG. 2, wherein
the preferred embodiment comprising 4 electrically-conducting
strata (12) is shown.) Each electrically-conducting stratum
(12) is joined in a coextensive union along the length of at
least one of its major surfaces with a non-conducting stratum
(13) of the same polymeric material to form an integral or
unitary filamentary structure ~11). As the component strata
of this structure cannot be individually separated or removed
from the unit, the integral structure (11) of the present
invention is decidedly different from those composite structures
of the prior art which, comprising distinct layers or plies
joined by adhesive and/or the application of heat and pressure,
are subject to delamination and/or des~uamation, which in
turn results in loss of conductivity of the structure.
Moreover, the electrically-conducting strata (12) of the
unitary structure (11) of the present invention are manifestly
unlike the prior art's long, slender particles of dispersed
conductive block copolymeric material, which are difficultly
fashioned in reproducible form from a narrow choice of
conductive polymeric materials. In contradist~nction to
these prior art structures, the electrically-conducting strata
(12) of the unitary filament (11) of the present invention
comprise finely divided particles of electrically-conductive
carbon black -- e.g., roughly spherical particles of electrically-
conductive carbon black having an average diameter of between
about 20 and 40 m~ -- uniformly dispersed in a non-conducting
polymeric matrix. Moreover, the desired electrical co~ductivity
of a variety of polymeric filaments is readily and economically
achieved, and easily reproduced.
;5~
The height of each electrically-conducting stratum
(12) is not critical. It varies with the diameter of the
filament (_), the number of strata contained therein, and
the consentration of carbon in each stratum. It is, of
course, preferable that the strata be well-defined and continucus.
However, it is emphasized that the drawings are
schematic and that the individual strata are not, and need not
be perfectly defined.
Each non-conducting stratum (13) of polymeric
material comprising the unitary filament ~11) of the present
invention is composed of the same polymeric material which
comprises the matrix of the electrically-conducting strata (12).
An explication and example of a pxeferred method of forming
the union of strata which is the integral ! filamentary structure
(11) of the present invention is now set forth.
To prepare integral, electrically-conductive fila-
~- ments according to the present invention, one may use a
number of special techniques, the most advantageous of which
comprehends a modification of the well-known technique of
spinning a solution of a fiber-forming polymeric material in
a solvent. This improvement comprises:
(1) providing a first stream of a solution of
the polymeric material;
(2) providing a second stream of the same solu-
. . .
tion of the polymeric material, and dispersing in the second
stream between about 30 and 70 percent by weight, based upon
the weight of the polymeric material, of a ~inely~divided,
electrically-conductive carbon black which does not dissolve
in, or react with the solvent;
(3~ providing a third stream identical to the first
stream;
(4) providing a fourth stream identical to the
second stream; and
~Q657~
(5) causing the first, second, third, and fourth
streams to join in order into a composite stream withou~
appreciable mixing of the individual component streams thereo,
and spinning the resulting composite stream into integral fila-
ments. The polymeric material is any of the well-known film
or fiber-forming polymers commonly employed in the art, examples
thereof being set forth above, and the solution thereof is
prepared by dissolving the chosen polymeric material in a
liquid which is a good solvent therefor, but which does not react
with or dissolve the finely-divided electrically-conductive
carbon black which is to be dispersed in the second stream by
standard techniques. The individual streams are first de-gassed,
after which they are joined by introducing them simultaneously
in parallel relationship into a cylindrical member which terminates
in an orifice or jet. If the "wet spinnlng" technique has
been chosen, the composite stream ls "spun" or extruded through
the jet into a coagulating bath, which containC a liquid
which is miscible with the polymer solvent, but is itself
a non-solvent for the polymer and causes the polymer to
precipitate. The filament so produced is then washed, generally
countercurrently with water, to remove the spinning solvent,
and is then dried and finally wound on a package for subse-
quent utilization in the production of a wide variety of
antistatic fabrics. If the "dry spinning" technique has
been chosen, the solvent contained in the composite stream
must be volatile, and the composite stream is "spun" or
extruded through the jet into the air or an inert gas
atmosphere, whereupon a filament is formed by evaporation of
solvent from the composite stream. Dry spinning is usually
effected in the art employing the cylindrical member in a
vertical position. Moreover, the cylindrical member is
generally jacketed for temperature control, and outfitted so
that the air, steam, or inert gas may be passed over the je~
;5~
either concurrently or countercurrently as required. Down-
ward spinning is preferred for low-denier fibers and
upward spinning for high deniers, for better control of draw
by eliminating the influence of gravity.
Found to be of particular significance and advantage
in the practice of this process is the step of introducing
the first and second streams referred to above simultaneously
into the inlet end of an interfacial surface generator and
then passing the resulting multi-layered composite stream
,
through the jet and into a coagulating bath or into the air
.~ or an inert gas atmosphere. Interfacial surface generators
such as those specified in U. S. patents 3,404,869 and 3,583,678
have been employed with beneficial results.
In a preferred embodiment, particularly good re-
; 15 sults are obtained in the preparation of filaments according
to present invention when the fiber-forming polyrneric material
is a long-chain synthetic polymer composed of at least about
~ 85~ by weight of acrylonitrile units with the remainder
: being one or more other mono-olefinic monomers copolymeriz-
. ,
able therewith, such as: vinyl acetate; alkyl esters of
~: acrylic and methacrylic acid; vinyl bromide; as well as
monomers having an affinity for acid dyestuffs, particularly
those containing a tertiary or quarternary nitrogen in the
molecule, such as vinyl pyridine or methyl vinyl pyridine;
and monomers having an affinity for basic dyestuffs, particularly
those containing a sulfonic or carboxylic acid group, such as
alkyl sul~onic acid, itaconic acid, among many others. The
electrically-conductive material employed in this preferred
embodiment is an electrically-conductive carbon black having
a particle size between about 20 and 40 m~. The acrylonitrile
polymer is dissolved in an inorganic solvent as specified
in U. S. Patents 2,558,730 and 2,916,348 or in an or~anic
;57~
solvent as shown in Knudsen, Textile Research Journal 33,
13-20 (1963). The first and second streams are introduced
into the inlet end of an interfacial surface generator as
specified in U. S. Patent 3,583,678 to produce a composite
stream of between 8 and about 2 thousand total layers, which
composite stream is then spun through a jet into a coagulating
bath, wherein the polymer is precipitated, and the unitary
; filament so produced is washed countercurrently with water, stretched, crimped and dried.
The present invention may be better understood
by a reference to the following illustrative examples,
wherein all parts and percentages are by weight unless
otherwise indicatedO
Example 1.
This example specifies detail concerning a
preferred method of making an integral, electrically-con-
ductive filament according to the present invention,
and sets forth some of the basic properties of the fila-
ment.
An acrylonitrile homopolymer, the preparation
of which is exemplified by U. S. Patent No. 2,~47,405,
was dissolved in a 60 percent solution of zinc chloride
to produce a stock solution containing about 11 percent
of the acrylic polymer. A first stream of this solution
was provided in a conduit. To a portion of the stock
solution which was used to provide the first stream was
added a commercially-available electrically-conductive
carbon black having an average particle diameter of 30 m~,
in an amount sufficient to provide a dispersion having
the foliowing composition: ~% acrylonitrile homopolymer,
6% carbon black. A second stream was provided from
this dispersion. Through the utilization of 2 metering
~Q~i5~
pumps, the first and second streams were introduced simul-
taneously into the inlet end of an interfacial surface
generator in the following proportion: 90 percent first
stream and lO percent second stream. The interfacial
surface generator, which is pictured and specified in U. S.
Patent No. 3,583,678, comprised 1 individual interfacial
surface generating element having 4 passageways therethrough.
Accordingly, the total number of layers generated was 8
(4 conducting and ~ non-conducting). The resulting composite
,
stream was spun through a jet into a coagulating bath of
4~ percent zinc chloride in water, and the unitary filamentary
structure so produced was washed countercurrently with water,
elongated to approximately 9 times its original length, and
dried in air. The filament was finally wound on a spool for
subsequent utilization in the production of an antistatic fabric.
The filament had a denier of 15 and a total carbon black
concentration of 5%. Using a Keithley 610C Electrometer,
- the electrical resistance of the filament was determined to
be 10 ohms/cm. This filament, which is hereinafter designated
Filament A, is compared with an acrylonitrile homopolymer
filament of 15 denier, which is designated Filament B, which
has an electxical resistance of 10l4 ohms/cm. See Table I.
Suc~ a comparison reveals that the desirable textile properties
o~ acrylic homopolymer filaments are retained by Filament A
while significant conductivity is achieved.
Example 2.
~ number of procedures otherwise identical to that
of Example 1 were carried out, except that the number of
electrically-conductive strata and the composition of each
electrically-conductive stratum in the integral filament
were varied as set forth in Table I on the following page.
Filaments C-E and others described below were prepared and
5~
their physical properties were determined. The results of
these determinations are also found in Table I. ~,
TABLE I
No of [C] in Total
Electri- Each Elec- [C] in
cally - trically - the Inte- Resis-
Conductive Conductive gral trance Extension Tenacity,
FilamentLayers Layer Filament - ohm/cm % g/den.
A 4 50% 5% 107 13.a 3.9
. (This
: Invention)
; B 0 0 0 1014 10.0 4.0
(For
: Comparison)
C 64 60% 10% 105 l4.6 3.3
(This
Invention)
D 1000 50% 2% 10 15.1 4.2
(This
Invention)
E 1000 50~ 5% 10 14.1 3.2
(This
Invention)
For more than about lOOO electrically-conductive
layers, the resistance of the filament exceeded lO9 ohms/
cm. For but one conductive layer, the filament fibrillated
undesirably.
Example 3.
This example is illustrative of the utilit,y and
durability of an integral, electrically-conductive filament
according to the present invention.
EXPERIMENT A
Filament A from Example l above was cut into staple
lengths of 3 inches and blended by standard techniques
with a 16-denier nylon 6 staple product having a staple
~6~
length of 6 inches to produce a blend contai~ing 2 percent
of Filament A. This blend was processed by standard
techniques into a 2.25/2 cotton count yarn having 3.5 Z
turns and 2.5 S turns per inch. This yarn is designated
Yarn A. Employing a jute backing material and utilizing
a standard tufting machine, a 30 oz/yd2 level loop carpet
(hereinafter designated Carpet A) was prepared from Yarn A.
EXPERIMENT B
Carpet A was then subjected to the Static Electricity
Test set forth below. The results of such testing are re-
ported in Table II below as "Initial Static Electricity."
Following the initial static electricity testing,
... .
Carpet A was then subjected to an accelerated wearing
procedure for 60 hours, after which, testing of static
electricity was again effected. The results of such
testing are reported in Table II below as "Final Static
Electricity."
From Table II it can be seen that carpet A was not
only initially static protected (viz., it did not allow the
generation of a static charge in excess of 3000 volts, which
is generally accepted as the average threshhold level of
human sensitivity), but carpet A was also static protected
after extensive wear. Moreover, microscopic examination of
the electrically-conductive filament A revealed substantially
no deterioration thereof.
Static Electricity Test:
The fabric to be tested is first cut into sample
squares 36 inches on a side. These samples are conditioned
for 7 days by being hung from racks in a test room equipped
with a rubber 100r mat and having an area of at least 100
square feet, wherein the temperature is controlled at 70+
2F and the relative humidity is controlled at 20%+ 1~.
~Q~
Free circulation of air over all sample surfaces is effected,
but the samples are not allowed to contact each other. A
pair of Neolite or PVC-sole test shoes is also conditioned
for the same period, under the same conditions.
Residual static charge on the rubber floor mat is
then neutralized by passing twice over its entire surface
a polonium wand, which consists of 6 polonium 210 alloy
strips mounted end-to-end on a head attached to a handle.
A fabric sample is then placed upon the xubber floor mat,
and its residual static charge is neutralized in the same
m~nnex. The soles of the test shoes are then cleaned by
sanding their entire surface with fine sandpaper, followed
by a wiping with cheesecloth to remove dust particles.
Wearing the test shoes and holding a hand probe
which is connected to an electrostatic detection head, a
human operator steps upon the carpet sample and grounds the
probe. Then while holding the hand probe, the operator walks
normally on the sample at a rate of 2 steps a ~econd for a
30-second period, being careful not to scuff or rub the
shoes over the fabric. If at the end of the 30-second
period the voltage has not xeached a steady maximum,
the walk is continued for an additional 30 seconds. The
maximum voltage recoxded during the walk is the static
level of the sample, the average for two sperators being
recorded in Table II as static electricity in volts.
~17~
i7g
Table II
Initial Static Final Static
Electricity, VoltsElectricity, Volts
~13 1~)
Carp~tNeolite Neolite
Sample SolesPVC Soles SolesPVC Soles
A (T~is 1400 1200 1500 1~00
Invention)
.- - ,f f ~,,
-18-
c -
Pile fabrics such as carpet A, the prepatation
of which is described above, when employed in an atmosphere
having a relative humidity of at least 20% will not generate
a static charge above about 3000 volts, which is in prox-
imlty to the threshold level of human sensitivity. Under
the same conditions, a standard nylon 6 carpet can generate
up to about 14,000 volts. Pile fabrics such as carpet A,
moreover, when containing an integral, electrically-conduc-
tive filament having an electrical resistance between about
104 and 109 ohmsjcm, do not present an electrocution hazard
to those contacting them in the event of an accidental and
simultaneous contact of such fabrics with a source of essen-
tially unlimited electrical current, as is available from an
ordinary electrical outlet, or an electrical appliance short-
circuited by insulation failure.
The unique combination of properties possessed by
the integral, electrically-conductive filament according to
the present invention renders it especially suitable as a
continuous filament or a staple product for use not only in
carpets, rugs, and other floor coverings, but also in bed
coverings, especially in hospitals; in curtains, especially
in hospitals for separation of cubicles; in articles of
apparel, especially uniforms and undergarments such as
slips; in hosiery, especially in panty hose and half hose;
in heater fabrics; and as sewing threads.
Although the present invention has been described
in detail with respect to certain preferred embodiments
thereof, it is apparent to those of skill in the art that
variation~ and modifications in this detail may be effected
without any departure ~rom the spirit and scope of the
present invention, as defined in the hereto-appended claims.
