U.S. patent application number 13/049484 was filed with the patent office on 2012-09-20 for conductive conjugate fiber.
This patent application is currently assigned to KB SEIREN, LTD.. Invention is credited to Toshihiro Iguro, Shinji Yoshida.
Application Number | 20120237766 13/049484 |
Document ID | / |
Family ID | 46828703 |
Filed Date | 2012-09-20 |
United States Patent
Application |
20120237766 |
Kind Code |
A1 |
Iguro; Toshihiro ; et
al. |
September 20, 2012 |
CONDUCTIVE CONJUGATE FIBER
Abstract
A conjugated conductive fiber including a non-conductive layer
and a conductive layer, in which: the non-conductive layer accounts
for at least 70% of a surface of the fiber; the non-conductive
layer is a polyester obtained by copolymerizing a metal sulfonate
group-containing isophthalic acid and a polyalkylene glycol; and
the conductive layer is a thermoplastic polymer containing titanium
oxide particles each having a conductive coating film. The
conjugated conductive fiber provides a polyester-based conjugated
yarn high in antistatic performance and easy to handle, which can
be dyed under normal pressure with improved color developing
property after dying.
Inventors: |
Iguro; Toshihiro;
(Sabae-shi, JP) ; Yoshida; Shinji; (Sabae-shi,
JP) |
Assignee: |
KB SEIREN, LTD.
Sabae-shi
JP
|
Family ID: |
46828703 |
Appl. No.: |
13/049484 |
Filed: |
March 16, 2011 |
Current U.S.
Class: |
428/373 |
Current CPC
Class: |
D01F 8/14 20130101; D01F
1/09 20130101; Y10T 428/2929 20150115 |
Class at
Publication: |
428/373 |
International
Class: |
D02G 3/00 20060101
D02G003/00 |
Claims
1. A conjugated conductive fiber, comprising a non-conductive layer
and a conductive layer, wherein: the non-conductive layer accounts
for at least 70% of a surface of the fiber; the non-conductive
layer comprises a polyester obtained by copolymerizing a metal
sulfonate group-containing isophthalic acid and a polyalkylene
glycol; and the conductive layer comprises a thermoplastic polymer
containing titanium oxide particles each having a conductive
coating film.
2. The conjugated conductive fiber according to claim 1, wherein a
mixing ratio of the titanium oxide particles each having the
conductive coating film in the conductive layer is 30 to 85 wt
%.
3. The conjugated conductive fiber according to claim 1, wherein a
ratio of the conductive layer to the non-conductive layer is 1:30
to 2:1 in terms of an area ratio of a cross-section surface of the
fiber.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a conjugated conductive
fiber in which the generation of static electricity is
suppressed.
[0003] 2. Description of the Related Art
[0004] Sweaters, fleeces, and the like, each of which are made of
acrylic fibers, are not free of generation of static electricity
when one takes off those clothes after wearing. In order to prevent
the generation of static electricity, there has been a demand for
conductive yarns which can be blended with the acrylic fibers.
[0005] In order to respond to this demand, blending of acrylic
fibers provided with conductivity has been considered. Some
approaches have been proposed heretofore (see JP-B-61-15167 and
JP-A-9-31747).
[0006] However, production of an acrylic conductive yarn involves
numerous problems. A method of producing the acrylic conductive
yarn is, for example, a method involving adding conductive
particles to an acrylic resin, e.g., such a complicated method as
described below. The method involves: preparing a spinning dope by
dissolving an acrylic polymer and conductive particles made of, for
example, conductive titanium oxide in an organic solvent; ejecting
the spinning dope to a coagulating solution; spinning the resultant
by a semi-dry method; and removing the solvent by a post treatment.
At the time of the removal of the solvent, voids occur in the
acrylic fiber itself, which adversely affects the conductivity of
the fiber.
[0007] In view of the foregoing, the use of a conductive yarn made
of another material has been considered. However, when the
conductive yarns made of the other material is blended with acrylic
fibers, it becomes necessary to perform two processes involving
dyeing the acrylic fiber and dyeing the other material.
SUMMARY OF THE INVENTION
[0008] A problem to be solved by the present invention is to
provide a conjugated conductive fiber which involves few problems
in being provided with conductivity and can be dyed under the same
conditions as those for an acrylic fiber.
[0009] The present invention has solved the above-mentioned problem
by constituting a conjugated conductive fiber as described below.
The conjugated conductive fiber is a conjugated conductive fiber
including a non-conductive layer and a conductive layer, in which:
the non-conductive layer accounts for at least 70% of a surface of
the fiber; the non-conductive layer is a polyester obtained by
copolymerizing a metal sulfonate group-containing isophthalic acid
and a polyalkylene glycol; and the conductive layer is a
thermoplastic polymer containing titanium oxide particles each
having a conductive coating film.
[0010] That is, the inventors of the present invention have
intensively studied a conductive yarn. As a result, the inventors
have focused on a conjugated conductive fiber obtained by melt
spinning to obtain a conductive fiber which can be dyed under the
same conditions as those for an acrylic fiber and involves few
problems in production. Then, the inventors have achieved the
present invention by using a polymer which can be dyed under the
same conditions as those for an acrylic fiber, i.e., which can be
subjected to cationic dyeing under normal pressure as a polymer in
the non-conductive layer of the surface of the conjugated
conductive fiber.
[0011] The conjugated conductive fiber of the present invention can
be industrially produced with ease at a low cost, and can be dyed
under normal pressure with good color developing property.
Accordingly, when the conjugated conductive fiber is blended with
an acrylic material, the fiber can suppress the generation of
static electricity of a product, and can be dyed under the same
conditions as those for an acrylic fiber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a view illustrating the cross-section surface of
the polyester-based conjugated conductive fiber in a first
embodiment of the present invention.
[0013] FIG. 2 is a view illustrating the cross-section surface of
the polyester-based conjugated conductive fiber in a second
embodiment of the present invention.
[0014] FIG. 3 is a view illustrating the cross-section surface of
the polyester-based conjugated conductive fiber in a third
embodiment of the present invention.
[0015] FIG. 4 is a view illustrating the cross-section surface of
the polyester-based conjugated conductive fiber in a fourth
embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] A non-conductive layer of a conjugated conductive fiber of
the present invention is a polyester obtained by copolymerizing a
metal sulfonate group-containing isophthalic acid and a
polyalkylene glycol.
[0017] The content of the metal sulfonate group-containing
isophthalic acid (hereinafter, referred to as "SIP") is preferably
0.5 to 10 mol % with respect to an acid component contained in the
polyester of the non-conductive layer. When the content of the SIP
is less than 0.5 mol %, cationic dyeability decreases, and dyeing
cannot be performed under the same conditions as those for an
acrylic fiber. As a result, when the conjugated conductive fiber is
blended with an acrylic fiber and then dyed, the conductive fiber
tends to appear as spots. Further, when the content of the SIP
exceeds 10 mol %, a degree of polymerization does not increase, and
the molecular weight of the polymer does not increase. As a result,
the polymer tend not to be formed into a fiber when spinning is
performed.
[0018] The SIP is, for example, a dimethyl 5-metal
sulfoisophthalate (hereinafter, referred to as "SIPM") or a
compound obtained by esterifying a dimethyl group of the SIMP with
ethylene glycol (hereinafter, referred to as "SIPE"). When the SIPM
is introduced into a slurry tank in a large amount, physical
properties of the slurry may be deteriorated. Accordingly, the SIPE
is preferably adopted.
[0019] Further, examples of the metal in the SIP include sodium,
potassium, and lithium. Of those, sodium is most preferred.
[0020] Further, the content of a polyalkylene glycol is preferably
1.5 to 6 wt % with respect to the polyester of the non-conductive
layer. When the content of the polyalkylene glycol is less than 1.5
wt %, dyeability under normal pressure deteriorates, and it becomes
necessary to perform dyeing under high pressure. As a result, when
the conjugated conductive fiber is blended with an acrylic fiber
and then dyed under normal pressure under the same conditions as
those for the acrylic fiber, a dyeing concentration of a conductive
yarn is low, and the yarn tends to appear as spots. Further, when
the content of the polyalkylene glycol exceeds 6 wt %, the degree
of polymerization does not increase, and the molecular weight does
not increase. As a result, the polymer tend not to be formed into a
fiber when spinning is performed.
[0021] Further, the polyalkylene glycol has an average molecular
weight of preferably 150 to 1,000.
[0022] When the polyalkylene glycol has an average molecular weight
falling within the above-mentioned range, dyeing can be performed
under normal pressure at around 100.degree. C., and a thickening
action attributed to a sulfonate group can be reduced because the
polyalkylene glycol exerts a plasticizing effect. As a result, the
degree of polymerization of the polymer can be increased.
[0023] The above-mentioned polyalkylene glycol is represented by
the general formula HO(C.sub.nH.sub.2nO).sub.mH (where n and m each
represent a positive integer). A polyethylene glycol where n equals
2 is most preferred because polyethylene glycol is universally
used.
[0024] The above-mentioned polyester specifically refers to a
polyester polymer capable of forming a fiber such as polyethylene
terephthalate, polybutylene terephthalate, or polyethylene
naphthalate. Further, the polyester may contain titanium oxide.
[0025] Further, the copolymerized polyester to be used in the
present invention desirably contains diethylene glycol (hereinafter
referred to as "DEG") at 4.5 to 6.0 mol %. DEG is produced by a
side reaction during the polymerization. When the content of DEG is
less than 4.5 mol %, cationic dyeing performance under normal
pressure deteriorates. Further, when the content of DEG exceeds 6.0
mol %, the heat resistance and oxidation resistance of the polymer
deteriorate. As a result, operability at a time of melt spinning
deteriorates markedly.
[0026] In addition, a concentration of terminal carboxyl groups in
the polymer is preferably set to 20 to 30 eq/ton. When the
concentration of the terminal carboxyl groups is less than 20
eq/ton, coloring of the polymer to be pushed out of a
polymerization tank is not good. When the concentration exceeds 30
eq/ton, the heat resistance deteriorates in a spinning process or a
post process.
[0027] The polyester to be used in the present invention preferably
has such a limiting viscosity that a ratio of a maximum value
[.eta.]max of the limiting viscosity to a minimum value [.eta.]min
of the limiting viscosity satisfies the relationship of
1.0.ltoreq.[.eta.]max/[.eta.]min.ltoreq.1.02. When the ratio
[.eta.]max/[.eta.]min deviates from the above-mentioned range,
operability tends to be inferior. For example, yarn breakage
frequently occurs at a time of melt spinning, and the lifetime of a
spinneret reduces because of poor spinning filterability.
[0028] The conductive layer contains titanium oxide particles each
having a conductive coating film. This way, the conjugated
conductive fiber is provided with conductive performance, and no
static electricity is generated when one wears clothes produced by
blending the conjugated conductive fiber with an acrylic fiber.
[0029] The conductive coating film is formed of, for example,
copper oxide, silver oxide, zinc oxide, cadmium oxide, tin oxide,
lead oxide, or manganese oxide.
[0030] A second component may be added to the conductive coating
film. The second component is, for example, a dissimilar metal
oxide or a similar or dissimilar metal. For example, suitable is a
component containing copper oxide/copper, zinc oxide/aluminum
oxide, tin oxide/antimony oxide, zinc oxide/zinc, aluminum
oxide/aluminum, tin oxide/tin, antimony oxide/antimony, or any one
of oxides thereof a part of which is reduced.
[0031] The titanium oxide particles each having the conductive
coating film have a specific resistance of, in a powder state,
preferably 10.sup.4.OMEGA.cm (order) or less, particularly
preferably 10.sup.2.OMEGA.cm (order) or less.
[0032] The specific resistance of the particles described above is
measured by: filling 10 g of a sample into a cylinder having a
diameter of 1 cm; applying a pressure of 200 kg with a piston from
the upper side of the filled sample; and applying a direct current
(0.1 to 100 V).
[0033] The titanium oxide particles each having the conductive
coating film each desirably have as small a particle diameter as
possible from the viewpoints of spinnability and conductivity. For
example, used are titanium oxide particles having an average
particle diameter of preferably 1 .mu.m or less, particularly
preferably 0.7 .mu.m or less, most preferably 0.5 to 0.01 .mu.m. As
the titanium oxide particles each have a smaller particle diameter,
when the particles are mixed with a polymer, the particles are more
excellent in dispersibility in the polymer and the resultant
mixture is more excellent in conductivity.
[0034] The conductive coating film can be formed by, for example, a
vacuum deposition method, or a method involving: causing a metal
compound (e.g., organic acid salt) to adhere; and sintering the
resultant to produce an oxide and partially reducing the oxide as
required.
[0035] Any known thermoplastic polymer can be used as the polymer
which forms the conductive layer by being mixed with the titanium
oxide particles having the conductive coating film. For example,
one can use polyamide, polyester, polyolefin, and polycarbonate.
Any thermoplastic resin is applicable as long as the resin takes on
a fiber shape when being subjected to melt spinning. Of those,
polyethylene is preferred.
[0036] A mixing ratio of the titanium oxide particles having the
conductive coating film in the conductive layer is preferably 30 to
85 wt %. The mixing ratio is more preferably 50 to 85 wt %, still
more preferably 60 to 85 wt %.
[0037] When the mixing ratio of the titanium oxide particles having
the conductive coating film falls within the above-mentioned range,
conductive performance is good.
[0038] In the conjugated conductive fiber of the present invention,
the non-conductive layer is requested to account for at least 70%
of the surface of the fiber. For example, suitable is a conjugated
fiber in which a non-conductive layer A and a conductive layer B
each have a cross-sectional shape as illustrated in any one of
FIGS. 1 to 4.
[0039] In consideration of the uniformity of dyeing, suitable is a
fiber in which the non-conductive layer A occupies the entirety of
the surface of the fiber as illustrated in any one of FIGS. 1 to
4.
[0040] A ratio of the conductive layer B to the non-conductive
layer A is preferably 1:30 to 2:1 in terms of an area ratio of the
cross-section surface of the fiber. The ratio is more preferably
1:30 to 1:1.
[0041] When the ratio of the conductive layer B is more than 2:1,
the strength of the fiber decreases, and spinning and winding tend
to be impossible. Further, when the ratio of the conductive layer B
is less than 1:30, the conductivity of the fiber becomes
insufficient, and the fiber tends to become incapable of exhibiting
an antistatic effect.
[0042] A method of mixing the polymer and the titanium oxide having
the conductive coating film, both of which are used in the
conductive layer B of the conjugated conductive fiber, is not
particularly limited. The mixing is performed by a known method
such as biaxial kneading. With the resultant conductive resin, the
production of the conjugated conductive fiber is performed by, for
example: melting the conductive resin and the polyester for the
non-conductive layer A, respectively; and ejecting the melted
products from a spinneret so that the products may each have, for
example, a cross-sectional shape as illustrated in FIG. 1.
[0043] After the ejected conjugated yarn has been cooled with cold
air, an oil agent is added thereto, and the yarn is wound with a
known winder. Thus, a multifilament or a monofilament is obtained.
Any winding speed is applicable as long as the speed is suitable
for the combination and ratio of the conductive layer and the
non-conductive layer. The speed is desirably 600 m/min to 1,600
m/min in terms of the quality of the yarn, ease with which the yarn
is wound, and the like.
[0044] The resultant un-drawn yarn is drawn while heat of 80 to
120.degree. C. is applied. Thus, the conjugated conductive fiber is
obtained.
[0045] The conjugated conductive fiber has an electrical resistance
value of preferably 1.times.10.sup.7 to 1.times.10.sup.11
.OMEGA./cm.
[0046] The drawn yarn has a monofilament fineness of desirably 1.5
to 5.0 dtex when the conjugated conductive fiber is blended with an
acrylic fiber.
[0047] Next, a method of utilizing the conjugated conductive fiber
of the present invention is described. The resultant conjugated
conductive fibers are bundled so as to have a fineness of, for
example, around 300,000 dtex, thereby providing a tow. The
conductive yarns formed into the tow are subjected to crimping by a
known method. After the crimping, a spinning oil agent is removed.
An after oil is added to the tow and the tow is dried so as to be
blended with acrylic fibers. After drying, the tow is cut so as to
have a length of 5 mm or less and then formed into a floc. The floc
is mixed into an acrylic floc which has been separately produced by
an ordinary method at one to several tens of percent by weight. Any
mixing ratio is applicable as long as the ratio is suitable for
antistatic performance necessary for the final product. After
mixing, the resultant is formed into a tow by a known method. The
resultant conjugated conductive fiber-mixed acrylic tow is further
combined with a non-conductive acrylic tow to further form a tow.
The tow is wound in a cheese shape as a spun yarn.
[0048] For cheese dyeing, the resultant cheese of the acrylic yarns
is dyed with a cationic dye at 98.degree. C. for 45 minutes to 60
minutes. The dyed conjugated conductive fiber-mixed acrylic yarns
are knitted by a known method and then subjected to a raising
treatment, thereby producing clothes such as fleeces.
[0049] The conjugated conductive fiber of the present invention is
innovative because the fiber can be dyed under the same conditions
as those for an acrylic fiber and does not appear as spots, and
clothes made of acrylic fibers each blended with the conjugated
conductive fibers of the present invention can suppress the
generation of static electricity as well.
EXAMPLES
[0050] Hereinafter, the present invention is specifically described
by way of examples. However, the present invention is not limited
thereto. It should be noted that each evaluation was performed as
described below.
(1) Antistatic Property
[0051] A wearing test was performed with respect to the antistatic
property by producing clothes in which the product of the present
invention was blended with acrylic fibers. The case where the
generation of static electricity, with crackling when one takes off
the clothes after wearing, was not observed was reported as
.largecircle.. The case where the generation of the static
electricity was observed was reported as x.
(2) Dyeability
[0052] Evaluation for dyeability was performed by: dyeing a product
obtained by blending the product of the present invention with
acrylic fibers under normal pressure with 2% omf of a Kyacryl Red
GL and 0.2 cc/l of acetic acid at a bath ratio of 1:50; and
visually evaluating the result. The case where spots of the
conjugated conductive yarn were not observed was reported as
.largecircle.. The case where spots were observed was reported as
x.
(3) Electrical Resistance Value
[0053] An electrical resistance value was measured by: cutting the
conjugated conductive yarn so that the resultant sample had a
length of 10 cm; applying a conductive paste (Product name:
DOTAITO) to both of the ends of the sample; then clipping both of
the ends of the sample with square-shaped aluminum foils about 1 cm
on a side; and clipping the aluminum foils with alligator clips of
an resistance measuring apparatus (measuring apparatus: AG4339B,
manufactured by Agilent Technologies, Inc., measuring environment:
23.degree. C..times.60% RH).
Inventive Example 1
[0054] Used as the conductive layer was a polymer obtained by
allowing polyethylene to contain 75 wt % of titanium oxide
particles coated with tin oxide doped with antimony oxide. Used as
the non-conductive layer was a polyester capable of forming a
fiber, the polyester containing 2.5 mol % of the SIPE with respect
to an acid component of the polyester and 5.0 wt % of a
polyethylene glycol having an average molecular weight of 200 with
respect to the polyester. It should be noted that, in the polyester
capable of forming a fiber in the non-conductive layer, a content
of diethylene glycol with respect to a glycol component was 5.9 mol
%, a concentration of terminal carboxyl groups was 25 eq/ton, and a
limiting viscosity ratio [.eta.]max/[.eta.]min was 1.005.
[0055] In order to provide each of the above-mentioned conductive
layer and non-conductive layer with a cross-section surface as
illustrated in FIG. 1, the layers were ejected while spinning from
an orifice having a temperature of 275.degree. C. and a diameter of
0.25 mm, subjected to cooling and oiling, wound at a speed of 1,200
m/min, and drawn while applying heat of 100.degree. C. As a result,
a drawn yarn having a fineness of 80 dtex/24f was obtained.
[0056] The resultant drawn yarn had a strength of 2.9 cN/dtex, an
elongation of 40%, and an electrical resistance of
5.74.times.10.sup.8 .OMEGA./cm.
[0057] Next, each resultant drawn yarns were formed into a
short-fiber floc as described above in detail. 10 weight percent of
the floc was contained in an acrylic floc, thereby providing a tow.
The resultant tow was combined with 19 non-conductive acrylic tows
so as to have a total content of 0.5 wt %. Thus, a spun yarn was
obtained. A cheese winding of the spun yarns was dyed with 2% omf
of a Kyacryl Red GL and 0.2 cc/l of acetic acid at a bath ratio of
1:50 and 98.degree. C..times.60 minutes. After that, the resultant
was knitted and then subjected to a raising treatment. Thus, a
fleece was produced.
[0058] In the resultant fleece, no dyeing spots were observed, and
the generation of static electricity in the wearing test was not
observed either.
[0059] Although specific forms of embodiments of the instant
invention have been described above and illustrated in the
accompanying drawings in order to be more clearly understood, the
above description is made by way of example and not as a limitation
to the scope of the instant invention. It is contemplated that
various modifications apparent to one of ordinary skill in the art
could be made without departing from the scope of the
invention.
[0060] The conjugated conductive fiber of the present invention is
a conjugated conductive fiber which: can be dyed under normal
pressure; has good color developing property; and can reduce the
generation of static electricity. The conjugated conductive fiber
is suitably blended with an acrylic fiber.
* * * * *