CA1285358C - Conductive composite filaments and fibrous articles containing the same - Google Patents

Abstract

62-20,860 comb.
CONDUCTIVE COMPOSITE FILAMENTS AND
FIBROUS ARTCLES CONTAINING THE SAME
Abstract of the Disclosure A conductive composite filament comprising a non-conductive sheath component of a fiber forming thermoplastic polymer and a conductive component consisting of a thick conductive core and a thin conductive path, which is lapped in said sheath and composed of a mixture of a thermoplastic polymer with inorganic conductive particles. The conductive path extends laterally from the periphery of the core, transversely through the sheath, up to or close to the outer circumference of the sheath and longitudinally along the entire length of the core, exposing its tip lengthwise continuously or intermittently and not more than 1.5 µm in width on the surface of the filament.

Description

62-20,860 comb.
CONDUCTIVE COMPOSITE FILAMENTS AN~
FIBROUS ARTICLES CONTAINING T~E SAME

The present invention relates to novel conduc-tive composite filaments, more particularly, conductive composite filaments which are industrially easily manufacturable, having substantially no metal abrasive 05 property, and further relates to antistatic fibrous articles containing the same.
It is well known that fiber~, particularly, hydrophobic fibers consisting of polyester, polyamide, polyacrylonitrile t polyolefin or the like, generate a lot of static electricity due ta friction, etc., often exceeding l0 kY, which cause~ various troubles.
Theref~re, many proposals rela~ing ~o destaticization (imparting of antistatic properties) have been made.
One of them is a process to blend electrifiable ibers with metallic fibers. Ho~ever, the metallic fibers have shortcomings, such as brittleness to induce breakages by bending during processing and using, which cause a decrease in antistatic propertyr Also the metallic ibers are difficult in blending, mixed weaving or mixed knitting with other ibers and, moreover, have an inherent metallic luster that impairs the quality of articles when the metallic fibers are incorporated therewith.

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Alternatively, metal deposited fibers and conductive material coated fibers also have many drawbacks, such as an extremely high cost of production, a low durability owing to liability to detachment of the 05 coating by bending or due to friction during processing and using, or the li~e.
Meanwhile, fibers composed of a thermoplastic polymer that contains conductive particles, for example, carbon black, metal particles, etc., dispersed therein, 10 when the conductive particles are dispersed in a~ amount large enough to provide a conductivity, cannot avoid decrease~ in spinnability, tenacity and elongation~
Conse~uently, it is extremely di~icult to obtain prac~icabl~ su~h fibers.
16 In order to obviate such drawbacks, compo~ite filament~ in which a conductive component composed of a thermoplastic polymer containing conductive particles, for example, carbon black, metal particles, etc., dispersed therein and a non~conductive component of a 20 fiber-forming thermoplastic polymer are bonded together in a side by side or sheath-core relationship uniformly extending along the longitudinal axis of the filament have been proposed in the gazettes oF Japanese Patent Application Publication ~os. 31,450/77, 44,579/78 and 25 25,647/82, Japanese Patent Application Laid~open No. 60-224,813, etc.

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Among the above proposed sheath-core type compo-site filaments, those having a non-conductive component completely encapsulating a conductive particles contain-ing conductive component, since dielectric breakdown in o~ the sheath portion to induce corona discharge hardly occurs, have a shortcoming that is a poor antistatic property. In contrast, sheath-core type composite filaments, different therefrom, having a sheath composed of a conductive component as well as side by side type 10 composite filaments wherein a conductive component and a non~conductive compo~ent are bonded together in a side by side relationship, since the conductive component is exposed on the filament surface t are excellent in corona discharging property, i.e., antistatic property.
16 However, these composite filaments exhibit noticeable black or dark grey color of carbon black or inorganîc conductive particles, deteriorate the appearance of article~ containing these filaments. ~oreover, these composite filaments having a hard conductive particles 20 containing conductive component exposed on the filament surface, when the filaments travel as rubbing upon a stationary body, abrade and eventually mar the body due to fri~tion. Therefore, such composite filaments thus provided with an augmented metal a~rasive property are 2~ involved in serious problems in the course of manufacturing and processing.

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In order to solve such problems, some proposals have been made. For example, the gazette of Japanese Patent Application Laid-open No. 60-110,920 discloses a core and thin skin type composite filament that 06 comprises a skin component having the thinnest portions of 3 ~m or less on the cross section. This filament is very excellent for obviating the metal abrasive property as well as providing the antistatic property. ~owever, if the non-conductive ski~ is made thin enough to lO provide a satisfactory antistatic property, the skin becomes liable to break, resulting in metal abrasion by the uncovered core. Accordingly, this type of filament still poses a problem such that stable manufacture is difficult to be performed. The gazette of Japanese 15 Patent Application ~aid-open ~o.60-224,812 discloses an improved core and thin skin type composite filament, where the skin is compo~ed of a fiber-forming polymer having conductive particles of metal oxide or metal compound, and more preferably the particle size ao satisfies the ~ormula; 0.5~ size of conductive particle/minimum thickness of skin 54. ~owever, if the conductive particles in the skin are contained much enough to provide a satisfactory antistatic property, the color or metal abrasion is revealed again.
2~ Further, in order to mitigate the metal abrasion during manufacturing and processing of composite ;i35~3 filaments, for example, of side by side type or the like that expose a conductive component on surfaces of the filament, there is disclosed, for example, in Japanese Patent Application Laid-open No. 61-132,626 a sheath-06 core type composite filament of which the sheathcomponent is composed of a solvent soluble polymer.
The sheath component of this filament can be removed by dissolving, ater fabricated into articles, to expose the conductive core component. In the gazette of 10 Japanese Patent Application Laid-open No. 61-152,823, there is also disclosed a conductive composite filament prepared by conjugating a mixture (A) consistin~ of a conductive polymer composition (P~') and a fiber-forming thermoplastic polymer (P2) which i5 incompatible with 1~ ~Pl') with non-co~ductive fiber-forming thermoplastic polymer. In this filament, the mixture ~A) occupies part of the sur~ace area of the ilament and part of (Pl') comes up to the surface in the lengthwise direction of the filament through an opening. ~owever t ao ~uch a conductive composite filament, in fact, is un-stable in yarn-spinnability and, moreover, insufficient in electroconductivity for lack of a conductive core a~
in the case of Comparative Example Y17 that will be described hereinafter. ~ccordingly, fibrous articles 26 containing such a filament are deficient in antistatic property and less practical. In the Japanese Patent 853~

Application Laid-open No. 57-161,1~6 r there is also disclosed a composite filament whose exposed conductive component occupies 30% or less of the surface of the filament. Although both of these filaments have an 05 excellent antistatic property and, in addition, careful consideration has been ~iven to prevent the metal abrasion in manufacturin~ and processing steps, these filaments inconveniently neces~itates use of special polymers or complicated apparatuses or imposition of 10 extraordinarily delicate conditions for manufacture.
An object of the present invention is to provide improved conductive composite filaments which h~ve high whiteness, excellent antistatic property, exhibiting no abrasive property, which can be commercially easily manufac~ured.
Another object of the present invention is to provide fibrous articles with excellent antistatic property and aesthetic appeara~ce which contain the conductive composite filaments of ~he invention.
The above objects of the present invention will be achieved by a unitary conductive composite filament which comprises:
(a) a non-conductive component composed of a fiber forming thermoplastic polymer, forming a sheath 2b extending along the entire length of the filament, and ~85358 (b) a conductive component consisting of a conductive core and a conductive path, being lapped in and extending lengthwise along said sheath, said conductive core being composed of a mixture of a 05 thermoplastic polymer with inorganic particles, said conductive path having a composition the same as or different from the conductive core, comprising a thermoplastic polymer and inorganic conductive particles, 10 which is characterized in that said conductive path extends laterally from a part of the periphery of said conductive core, transversely through the sheath, up to or close to the outer circumference of the sheath and that the conductive path is exposed at least partly lB lengthwise and not more than 1. 5 ~m in width on the outer peripheral surface of the sheath.
For better understanding of the invention, reference is made to the accompanyin~ drawingsl wherein:
FIGS. 1-6 show the cross-sectional views of the conductive composite filaments of the present invention;
FIGS~ 7-11 show the cross-sectional views of the conventional conductive composite filaments, FIG. 7 of a sheath-core type and FIGS. 8-11 of side by side type ~ilaments;
2~ FIGS. 12-14 are polymer flow diagrams in a spin-neret assembly to be preferably employed for manufactur-~535~3 ing the filaments according to the present invention;
FIG. 1~ is a graph showing the relation between the blend ratio of the conductive composite filaments and the amount of the electrified charge in an example 05 of the fibrous article, a nonwoven fabric composed of polyethylene terephthalate staple fibers, of the present invention;
FIG. 16 is a graph showing the relation between the pitch of the conductive composite filaments spacedly 10 incorporated into a fibrous article, i.e., a circular knitted fabric, and the voltage of frictional electrification;
FIGS. 17 and 18 are SEM photomicro~raphs showing the cross-seYtional view and side surface view, 1~ respectively, of ~he conductive composite filaments of the present invention ~undrawn filaments); and, FIG. 19 is a SEM photomicrograph showing the cross-sectional and peripheral views of an example, the conductive composite filament Y3, of the invention (the ao PE composing a conductive component has been removed from the undrawn filament).
The cross sectional figure of the composite filaments according to the present invention is not specifically limited. It may be either circular or non-circular, but the circular one is preferred.
In the composite filaments of the present Si3~3 invention, the cross-sectional figure of the conductive component is important. As is shown in FIGS. 1-6, the cross-sectional figure of the conductive component consists of a thick conductive core 1 and a thin conduc-OB tive path 2, both lapped in a sheath 3 composed of anon-conductive component extending along the entire length of the filamentc The conductive path ~ extends laterally from a part of the periphery of the thick conductive core 1, transversely through the sheath 3, up 10 to or close to the outer circumference of the sheath.
Longitudinally, it extends along the entire length of said core in such a manner that the conductive path is e~posed at least partly len~thwise and not more than 1.5 ~m in width on the outer peripheral surface of the 1~ sheath, For the conductive component, a tadpole-like figure is particularly preferred which is composed of the conductive core as its head and the conductive path as its tailA With respect to the position of the con-ductive component in the cross-section of the filament, it is preferred that the conductive core embedded in the sheath is positioned nearly in the center of the filament and only the tip of the conductive path barely reaches the circumference of the filament.
The cross-sectional figure of the conductive component may be either same or different throughout the .

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entire length of the Eilament. In particular, the figure or width of the conductive path may vary gradually along the longitudinal axis of the filamentO
This means that the thick conductive core extends Ob continuously along the length of the filament and the thin conductive path can be exposed either continuously or intermittPntly lengthwise on the surface of the filament.
The cross-sectional figure of the conductive 10 core may be arbitrarily selected from circular, elliptical, triangular, rectangular or the like.
~he conductive core occupies a major portion, for example, at least 60~ by volume, of the conductive component. Its thickness, for example, dl in FIG. l, is 15 preferably at least 5 ~m. There may be either case where the coxe is clearly distin~uishable (e.g~, FIG. l) or indistinguishable ~e.g., FIGS. 2 and 5).
The conductive path means a thin portion conjoined with the conductive core. Its cross-sectional 20 figure may be straight and, however, a bent or crooked one is more preferred for narrowing the exposed width o its tip. Additionally, from the ioint with the conductive core to the tip, of the conductive path, the thicknesses may be substantially same (FIG. l) and, 2~ however, those gradually attenuated (FIGS. 2, 4 and 5) or thin-and-thick (FIG. 6) are preferred for controllins 5~3 the exposed width narrow as desired. In contrast, when the conductive component consists solely of a thin band without having a core (thick portion) as shown in FIG. 10, the electric conductiv;ty or antistatic o~ property is apt to decrease or become unstable, while, if it is formed thick, the metal abrasive property will increase appreciably, so that this type of the conductive component is not suitable.
The width of the conductive path that i5 exposed 10 on surfaces of the filament (e.g., d2 in FIG. 1) is not more than 1.5 ~m, preferably not more than 1.2 ~m, most preferably not more than 1.0 ~m. If the exposed width is too large, the metal abrasion becomes liable to occur.
1~ In the composite filaments according to the present invention, the conductive path may be exposed lengthwise intermittently on the surface of the fila-ment. The portion to be exposed is the tip or a part of its vicinity of the conductive path. The length along the longitudinal axis of the filament of the exposed portion is not specifically defined. ~owever, the proportion of the exposed length to the entire length oE
the filament is preferably not more than 9o%~ more preferably not more than 70%, most preferably not more than 50%. Too large the width or the length proportion o the exposed portion tends to cause metal abrasion.

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A5 explained above, the composite ~ilaments according to the present invention have a novel cross-sectional figure that is quite different from those of any conventional sheath-core or side by side type o~ conductive composite filaments.
The conjugate ratio, that is, the area ratio occupied by the conductive component in the cross-section of the composite ~ilaments is preferably 3-40~, more preferably 4-20%r most preferably 5-15%. WhPn the conjugate ratio is too small, the conductivity will decrease, lessening therefore the antistatic property.
Alternatively, when it is too large, physical or mechanical properties of the filaments will be deteriorated and the metal abrasive property will be 1~ augmented.
As the inorganic conductive particles to be used in the pre3ent invention, any kind of particles can ~e employed insofar as they have a specific resistance in powdery form of not more than about 104 Q-cm. Not only those particles coated with a metal oxide or metal hydroxide having high whiteness but also metallic powders (e.g., silverr nickel, copper, iron, alloys thereof, etc.) and metallic compounds such as copper sulphide, copper iodide, zinc sulphide, cadmium sulphide 2~ and the like, can be employed.
As metal oxide particles, mention may be made of ~ 3 ~8 particles of tin oxide, zinc oxide, copper oxide, cuprous oxide, indium oxide, zirconium oxide, tungsten oxide, etc. Most metal oxides are insulators or semi-~onductors and do not show enough conductivity to o~ satisfy the object o~ the present invention. ~owever, the conductivity is increased, for example, ~y adding a small amount (not more than 50%, particularly not more than 25~) of a proper ~econdary component (impurity~ to the metal oxide, whereby conductive metal oxide powders 10 having sufficient conductivity to satisfy the object of the present invention can be obtained. As such a secondary component, i.e., a conductivity modifier~
antimony oxide can be used for tin oxide, and also oxides of aluminum, gallium, indium, ~ermanium, tin ancl lB the like for zinc oxide.
Further, particles wherein a conductive film o~
the above-described me~al oxides or other metallic compounds is formed on surfaces of non-conductive inorganic particles, such as titanium oxide, zinc oxide, ao magnes;um oxide, tin oxide~ iron oxide, silicon oxide, aluminum oxide and the likej also can be used. In the case where particularly high whiteness is required, it is prPferred to use conductive particles which is obtained by mixing tin-oxide-coated titanium oxide 26 particles with antimony oxide and firing the resulting mixture.

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The conductivity of t~e conductive metal oxide particles is preferred to be not more than about 104 Q-cm, particularly not more than about 102 Q cm, most preferably not more than about 101 Q~cm in specific resistance in the powdery state. In fact, the particle having about 102 Q cm ~ 10-2 ~-cm are obtained and can be suitably applied to the object of the present invention.
The particles more excellent in conductivity are more preferable. The specific resistance (volume resis-lO tivity) is measured by charging 5 9 of a sample into aninsulative cylinder having a diameter of 1 cm and apply-ing a pressure of 200 kg to the cylinder from the top by means of a piston and applyin~ a direct current voltage (for example, 0.001-1,000 V, current oE 1 mA or less).

16 The conductive particles are preferred to be sufficiently small in the grain size. Particles having an average grai~ size of 1-2 ~m can b,e used but t în general, those havin~ an avera~e grain size of not more than 1 ~m, particularly not more than 0.5 ~m, most 20 preferably not more than 0.3 ~m, are suitably used.
~ he term "grain size" used herein means the weight average diameter of single particles. A sample is observed by an electron microscope and is separated into single particles. Diameters ~mean values of the long diameter and the short diameter) of about 1,000 particles are measured and classified by a unit of 5~3 0.01 ~m to determine the grain size distribution and then the weight avera~e grain size is determined from the following formulae (I) and ~II).

~ NiWi2 Gmin ~uer~ge weight W = ~
~ NiWi wherein Ni, Number of particles classified in NoO i, and Wi: Weight of particles classified in No. i.

Grain weigh~ W = ~ pD3 (II) wherein p : Density o~ particle, and D : Diameter o~ particle.
The mixed ratio of the conductive particles in the conductive component depends upon the kind, conduc-tivity, grain size, chain forming ability of particles, and the property, crystallinity, etc. of the polymer binder the particles are mixed with. ~owever, it is generally within a range of about 10-85%, preferably about 20~80%, by weight. For example, the mixed ratio of titanium oxide particles coated with a conductive ~ilm is generally in the ran~e o~ about 40-85%r more preferably 50-80~, most preferably 60-80%r by weight.
The thermoplastic polymer to be mi~ed with the inorganic conductive particles, which forms the 5~3 conductive component, is not particularly limited and can be selected arbitrarily from a host of thermoplastic polymers such as polyamides, polyesters, polyoleins, polyvinyls, polyethers and the like. These polymers are 05 preferred to have fiber-formability from the standpoint of spinning operation. ~owever, even thou~h those polymers deficient in fiber-formability are used, compo-site filaments can be provided with sufficiently good spinnability by using a fiber-forming thermoplastic 10 polymer as the non-conductive component to be conjugated therewith. As the thermoplastic polymers used for the conductive component, particularly preferred are those having a crystallinity of at least 60~, which are poor in compatibility with the non-conductive fiber-formin~
16 thermoplastic polymers. Such polymers include poly-ethylene, polypropylene, polyoxymethylene, polyethylene oxide and its derivatives (~or example, ethylene oxide/ethylene terephthalate block copolymers), polyvinyl alcohol, polypivalolactone, polycaprolactone, 20 etc. Among these polymers, polyethylene, polypropylene polyoxymethylene, and copolymers thereof, are particularly suitable ~ he conductive component is preferred to have a specific resistance ~volume resistivity) of less than 2~ 107 Q cm, more preferably not more than 104 Q-cm, and not more than 102 Q cm is particularly preferred.

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To the conductive component may be further added dispersants ~or example, waxesr polyalkylene oxides, various surfactants, organic electrolytes, etc.), coloring a~ents, pigments, stabilizers (antioxidants, 05 ultra~iolet ray absorbents, etc.) flow improvers and other additives.
As the fiber-forming thermoplastic polymers to form the non-conductive component in the composite filaments of the invention, any spinnab~e polymers can 10 be used. Among the spinnable polymers, polyamides such a~ nylon-6, nylon-6~r nylon-12, nylon-610 and the like, polyesters such as polyethylene terephthalate, poly-ethylene oxy~enzoate, polybutylene terephthalate and the like, polyacrylonitrile and copolymers and modified 1~ polymers thereof, are particularly suitable. ~o the fiber-forming thermoplastic polymers may be added additives~ such as delustrants, pigments, coloring a~ents, stabilizers, antistatic agents (such as polyalkylene oxides, various surfactants or the like).
20 However, addition of inorganic particles in such a large amount as to:possibly induce metal abrasion is not preerred. ~he non-conductive componen~ composed of a fiber-forming thermoplastic polymer as described above is preferred to have a specific resistance of at least 2~ 107 Q-cm.
Meanwhile, in the conductive component of the ~.~8~3S8 composite filaments according to the present invention, t~e conductive core and conductive path usually have substantially the same composition. ~owever, in a preferred embodiment, the thermoplastic polymer composi-06 tion in the conductive path consists of a mixture of thepolymer for the non-conductive sheath component with the polymer composition for the conductive core component.
the mixing ratio of the both components is not specifi~
cally limited. However, a mixing ratio such as to bring 1~ the content in the mixture of the conductive inorganic particles into the range of 3-50%~ particularly 5-40%~
by weight, is preferredO If the content is too large, the composite filaments ~oo much increase in metal abrasive property, whilet if too small, the antistatic 16 property becomes insuficient. ~he mixture i5 preferred to occupy at least the exposed portion on filament surfaces of the conductive path.
The above-described polymer mixture can be produced according to any known processes~ For example, 20 use may be made of a process for mixing by means of a static mixer composed of relatively a few, preferably 1-3 mixing elements which is provided in a polymer flow path inside a spinneret assembly lFIG. 12)t a mechanical mixer such as an impeller or rotor ~IG. 13), a hydro-26 dynamic mixing utilizing collision of fluids caused byhigh pressure injection or a breaker such as glass beads ~ ~Si3~8 or a ilter layer provided in the ~low path ~FIG. 14), etc., and combinations thereo. In FIGS. 12-14, the numeral 101 denotes an entrance for a fiber-forming thermoplastic polymer; 102, an entrance for a conductive 05 component polymer composition; 103, a static mixer; 104, a kneader; 105, a mixing zone; 106-108, meeting points;
109, a constriction device, and llD, a spinneret.
The fiber-forming thermoplastic polymer and conductive component polymer composition to be mixed lO with each other are preferred to be mutually in-compatible. Such a combination provides a mixture in a mutually phase-separated state. Alternatively, in the case of mutually compatible combinations, an unevenly mixed state, for example, a ~ine archipelagic or multi-16 layeredly dispersed state is preferred from theviewpoint of corona discharging.
The reason why the excellent antistatic property and metal abrasion resistance that are the objects o the present invention are achieved by virtue of the 20 ~pecified figure of the conductive component comprising a thick conductive core and a conductive path of which only the tip reaches to the peripheral surface of the filament, is accounted as follows: the thick conductive core, for example, having a thickness of not less than 2~ 5 ~m and a specific resistance of not more than about 107 Q cm, extending continuously along the entire length ~.~ 8S~ ~

of the filament, is considered to make movements in the longitudinal direction of the electric charge easyO
This function, since the conductive core has a thickness larger than a certain degree, will not be deteriorated 05 in processes such as drawing, false-twisting, rewinding, knitting, weaving and the like~ Alternatively, since the conductive path conjoined with the thick conductive core reaches its tip up to or close to the surface of the filament and is exposed lengthwise continuously or 10 intermittently, when the filaments are electrified, destaticization by corona discharge is considered to occur at a low potential.
Thus, by incorporatin~ the composite ~ilaments of the prese~nt invention in a very small amount, ~ibrous 15 articles provided with an excellent antistatic property can be produced without impairing aesthetic appearance, such as apparels, lingerie, foundations, hosiery, particularly working clothes for clean rooms, she~tings, carpets, upholsteries, interior cloths, or the like.
20 The composite filaments of the invention may be mixed with other natural fibers or artificial fibers and used as continuous filament yarnsr staple fibers, in a non-crimped, crimped, undrawn or drawn form.
The present invention will be further explained 2~ by way of examples.
In the examples, the antistatic property was 535~3 evaluated according to the following method.
~n ordinary nylon-6 drawn yarn (210 deniers/54 filaments) was knit on a circular knitting machine, incorporating a conductive composite filament yarn in every eleventh 05 coursel to prepare a tubular knitted fabric mixed with 0~85% based on the weight of the fabric of the conduc-tive composite filaments. The resulting fabric in which oils were removed by scouring was thoroughly washed with water, then dried at ~0C for 3 hours and fur~her 10 conditioned at 25C in an atmosphere of 30% R.~. for 6 hours. Thereafter, the fabric was rubbed 15 times with a cotton cloth at the same temperature and humidity as the above, and the electrified charge after 10 seconds was measured.
The metal abrasive property was measured by the time required ~or b~eaking a ~tainless steel wire having a diameter of 35 ~m, when the filament yarn traveled on the stainless steel wire at a speed of 100 m/min.
(The yarn tension before contacting was 4-5 9 and ~he 20 contact angle was 453.
The electric resistance was measured of a yarn consisting of 5 single filaments having a length of 10 cm. ~oth ends of the yarn were bonded to metal terminals with a conductive adhesive (Dodite D-55~, 26 manufactured by Fuiikura Kasei K.K.), 10 V of direct current was applied between both the terminals, and the 535~3 - ` electric resistance was determined. ~he specific resistance of the conductive component was calculated ~rom the above obtained value of the filament yarn.
The following examples are given for the purpose ~6 of illustration of this invention and are not intended as limitations thereof.

Conductive particles having an average grain size of 0.25 ~m and a specific resistance of 6.3 Q cm 10 was obtained by firing a mixture of titanium oxide particle~ coated with a tin oxide film and 0.7s% by weight of said particles of antimony oxide. Seventy-five parts by weight of the above obtained particles and 25 parts by weight of polyethylene having a molecular 1~ weight of 80,000 were kneaded together to prepare a conductive polymer composition Al. This conductive polymer composition Al and nylon-6 having a relative viscosity in 95~ conc. H2SO4 of 2.3 were simultaneously spun from orifices having a diameter of 0.25 mm at a 20 spinning temperature of 280C into composite filament yarns having cross-sectional figures a~ shown in Table 1, with a conjugated ratio of 1/9 (areal raio in cross section)O The as-spun yarns were taken up on a bobbin at a rate of 800 m/min., while cooling and 2~ oiling. Then the taken-up filament yarns were drawn at a draw ratio of 2.6 times on a hot roll at 80C, further ~ ¦A

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contacting with a plate heater at 170C, to produce drawn yarns Yl~Y5 of 20 deniers/3 filaments which were wound up on a pirn.
T~e conductivity ~specific resistance), antistatic propexty and metal ahrasive property of these filament yarns are giv~n in Table 1.

Table 1 Yarn No. Yl Y2 Y3 ~4 Y5 _ _ _ _ Cross-secti~nal FIG.l FIG.3 FIG.6 FIG.7 FIG.s ~igure _ Thickness o~ core: 8 8 8 9 7 Strua- dl ~m~ _ _ ture Widthofconductive l 2 1.2S2.0 _ 2.5 . path: d2tY~) _ _ __ __. . ._ Width o e~posed1.2 Sl.2 53.9 _ 2.5 portion (~m~
_ ~ ___ _ _ . __ Specificresistance5XlO2 lXl03 ~XlO2 7Xl02 9X1~3 (Q-cm~ _ ~
P~oper- Antistaticl 6 1.7 1.7 3.4 1.6 ties property (kV) __ ___ __ Metal abrasive 24 30 31 35 8 property (min.) _ . _ _ . ~his This This Rrior Prior Remarks inven- inven- inven- art art tion tion tion . ~ . _ ~ ny of the yarns Yl~Yg had a specific resistance of not more than the order of 103 Q-cm and exhibited good conductivity. The yarns Yl~Y3 and Ys had good antistatic properties but the yarn Y4 that had not ~.~8535~

exposed the conductive polymer component on the filament surface was poor in antistatic property. Additionally, the yarns Yl~Y~ had a little metal abrasive property but the yarn Ys exposing the conductive component largely in o~ width on the surface of the filament had an extremely increased met~l abrasive property. The yarn Ys could not be stably manufactured due to increased abrasion of thread guides.
Next, the yarns Yl~Y4 were respectively plied 10 with a nylon-6 filament yarn of 2,600 deniers/
140 filaments and the plied yarns were crimped by texturizing. Using the texturized yarn in every fourth course and only the nylon yarn in every three courses, a tufted carpet (looped, the mixed ra~io o~ the conductive 1~ filaments: 0.17~) was produced. A cha~ged voltage of a human body generated when a man putting on leather shoe~
walked on the re~ulting carpet in a room at 25C with 20% R.X. was measured. The charged voltages of the carpets incorporated with the yarns Yl~Y3 of the present invention were -2.0 kV, -2.3 kV and -1.8 k~, respec-tively~ In contrast, that of the carpet incorporated with the yarn Y~, a sheath-core type composite filament yarn, was -4~3 kV and an electric shock was received from a grounded doorknob. For the purpose of compar-26 ison, the charged voltage of human ~ody of a carpetcomposed only of ny1on was measured -9.2 kV and the 2~

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- ` electric shock received ~rom the grounded doorknob was so violent that a considerable fear was felt.

A polyethylene terephthalate polymer having a 05 molecular weight of 15,000 blended with 0.65% based on the weight of the polymer of titanium oxide as a delustrant was used as a non-conductive polymer and the conductive polymer composition Al prepared in EXAMPLE 1 was used as a conductive polymer composition. These 10 polymers were conjugated, in a spinneret, in side by side relation having a cross-sectional figure as shown in FIG~ 3, and spun from orifices having a diameter of 0.3 mm at a spinning temperature of 285C. After quenching and oiling, the as-spun ~ilament yarn was 1~ wound up on a take-up roll at a rate of 1,000 m/min.
Then the yarn was drawn 3.1 times its originàl length using a hot roll at 85C, heat-set with a plate heater at 150C and wound up on a pirn. Thus, conductive composite filament yarns Y6~Yg were obtained~ These 20 filament yarns had properties shown in ~able 2.

,~

Table 2 ~_ . _ Yar~ ~o. Y6 Y7 Y8 Y9 _ _ _ Filament 20/3 2~/4 20J5 20/6 composition (d~f) ~ .
Thi~knes~ Df core: 8 7 6 5 Struc- dl ~m~
kure ~ = 51.2~1.2 ~l.0 51.4 path: d~ (~m __ Width of expo~ed ~l.2 ~1 2 Sl.0 ~l.0 p~rtion (~m) _ _ ~. _ Specific re~istance 3XlO~ 6X102 2X143 4X104 ~Q-cm) _ _ ___ _ Proper- Antistati~ property 1.7 1.5 1.7 1.8 ties ( kV) __ H~tal abrasiv~ 30 28 3130 property (mi~.~
__ _ This ~hi~ ThisThis Remaks inven- in~en- inven- inven-tion tion tion tio~
~ _ . _ Titanium oxide particles coated with tin oxide (SnO2) and 1~5% based on the weight of the particles of antimony oxide were mixed together and fired to produce conductive particles having an average grain size of 0.25 ~m, a content of tin o~ide of 15% by weight, a specific resistance of 7 Q-cm and a whiteness, i.e., light reflection, of 83%. Seventy-five parts by weight of the produced conductive particles and 25 parts by weight of a low density polyethylene having a molecular i358 weight of about 50,000 and a melting point of 103C were mixed and kneaded uniformly together with 0.5 parts by weight of magnesium stearate (a flow improver) to prepare a conductive polymer composition that was 05 denoted as ~2. Nylvn-6 having a molecular weight of about 16,00~ and a melting point of 215C admixed with 0.8% based on the weight of the nylon of titanium oxide to prepare a polymer Bl.
The conductive polymer A2 and the polymer Bl 10 were conjugate-spun with a conjugate ratio of 9tl at a spinning temperature of 280C from orifices having a diameter of 0.25 mm into composite filaments having cross-sectional figures as shown in Table 3.
The as-spun filament yarns were wound up on a take~up roll a~ a rate of 800 m/min., while guenching and oiling. Then the yar~s were drawn 2.6 time~ their original lenyths with a hot roll at 80C~ further brought into contact with a plate heater at 170C, and wound up on a pirn. Thus, drawn yarns Ylo~Y13 of 20 lB deniers/l filament were obtained.
The properties of these drawn yarns, such as conductivity (specific resistance), antistatic property, metal abrasive property or the like, as well as the illustrations of side surface views of the filaments observed by SEM are shown in Table 3.

3S3~3 Table 3 _ _ _ _ __ rarn No. Ylo Yll Yl2 Yl3 _ . ~_ Cross-s~ctiona1 ~IG.3 FIG.7 FI~.8 FIG.9 _ _ ~xposure of conduc- Inter- contin- co~tin-Stru~- tive path on mittently, no uously, uo~sl~, tur~ filame~t surfaces yes yes yes Width of conductive0.5~1.0 ~0) 4 2 path: d2 (~m) _ Perce~t Exposure 40 (0) 10~ 100 ~ _ _ Tens le strength 3.1 2.9 2.8 2.5 _ _ Elongation at break 71 64 67 78 _ _ Proper- Specific resistance7X103 7Xla3 7XlC3 7XlD3 ties (Q cm~
_ _ _ _ Antistatic 1.8 3.2 1.5 1.6 property ~kV) _ __ _ __ _ Natal abr~siva 35 35 4 8 prop~rty (mi~.) _ ~ _ _~
This Compar- Compar- Co~par-Remarks invention at;ve ative ative ~ ___ Any of the yarns Ylo~Yl3, had a specific resistance of the order of 103 Q cm and exhibited good conductivity. The yarns Ylo~Yl2 had a good antistatic property of not more than 2.0 kV, but the yarn Yll whose conductive polymer component was not exposed on the surface o~ the Eilaments had a poor antistatic property.
Further, the yarns Yl~ and Yll had a decreased metal abrasive property, while the yarns Y12 and Yl3 showed a considerably increased metal abrasive property.

~ 3~

The yarns Y12 and Y13 abraded travellers ~o remarkably during draw-twisting operation that the stable manu-facture of the yarns oould not be performed. The yarn Ylo was the only yarn that had a good antistatic 06 property as well as a decreased metal abrasive property.

A non-conductive polymer of polyethylene terephthalate having a molecular weight of 15,~00, blended with 0.65 weight ~ of titanium oxide as a 10 delustrant and the conductive polymer composition A2 used in EXAMPLE 3, were conjugated, in a spinneret, in side by side relation such as cross-sectional figures shown in Table 4, as covering the conjugated polymers with a thin sheath of the non-co~ductive polymer, and 1~ spun from orifices having a diameter of 0.3 mm at a spinnin~ temperature of 282C. After quenching and oiling, the as-spu~ filament yarn was wound up on a take-up roll at a rate of 1,000 m/min. Then the yarn was drawn 3.1 times it~ original length using a hot roll ao at 85C, heat-set with a plate heater at 150C and wound up on a pirn. Thus, composite filament yarns Yl4~Y17 were obtained. Those filament yarns had cross-sectional figures and properties shown in Table 4.

,.~

Table ~
= Yarz~ No. Y14 Y15 Y16~17 Cross-sectional FIG. 1 FIG. 5 FIG. 6 :EIG. 11 figure _ _ Exposure o~ conduc- Inter- Inter- Inter- I~ter-Stru~- tive path on mittent mittent mittent mittent ture ~ilament surfaces _ __ Width of ~onductive0~ 5~1. 0 O . 5~1. 0 0.5~1.0 0.5~1.5 path: d2 (~
Percent exposure ~) 30 50 40 50 _ _ _ __ Specific r~sistance 5X103 sX103 5XlG3 ~X107 (g~d) _ Pr~pe~- An~istzltic property 1 8 1.6 1.5 3.8 ties ~ _ .
Netal abrasive 35 3~ 30 28 property (mirl~) , _ ~ _ This This This Compar-Remarks inven- inverl- inven- ative tion tion tion _ _ _ On the peripheral surfaces of the yarns Yl4~Yl7, intermittent unevennesses caused by the conductive polymer were observed by SEM. All of these yarns exhibited ~ubstantially no metal abrasive property so that no troubles occurred in spinnin~, drawing, knitting and w*aving processes. The yarns Yl~~Y16 had a good antistatic property. The ~arn Y17 that lacked the thick conductive core was high in specific resistance and poor in antistatic property.

3~8 Titanium oxide particles coated with tin oxide and 0.75~ based on the weight of the particles of antimony oxide were mixed together and fired to produce o5 conductive particles having an average grain size of O.Z5 ym and a specific resistance of 6.3 Q~cm, Seventy-five parts by weight of the produced conductive parti-cles and 25 parts by weight of a polyethylene having a mole~ular weight of 80,000 were mixed and kneaded 10 together to prepare a conductive polymer composition A3.
Using a spinning machine provided with a static mixer comprising a couple of mixing elements in a spinneret assembly such as shown in FIG. 12, 10 parts by volume of the above conductive polymer A3 and 90 parts 1~ by volume of a nylon-6 (Nl) ha~ing a relativ~ viscosity in 95% conc. ~ZSO4 of 2.3 were spun frorn orifices having a diameter o 0.25 mm at a spinning temperature of 280C
to form filaments with cross-sectional figures and mixing ratios as shown in Table 5. In the spinning, the 20 polymers Nl and A3 were introduced from the entrances 101 and 102, respectively, and the constriction devices 109 were adjusted to control the mixing ratio.
The as-spun filament yarns were wound up on a take-up roll at a rate of 800 m/min., while quenching and oiling. Then the yarns were drawn 2.6 times their original lengths with a hot roll at 80C, further ,~.

535~3 brought into contact with a plate heater at 170C, and wound up on a pirn. Thus, drawn yarns Ylô~Y20 of 20 de~iers/3 filaments were obtained.
The properties o~ these conductive composite filament yarns, such as conductivity (specific re~istance), antistatic property and metal a~rasive property, are shown in Table 5.

Table 5 _ . _ _ _ Yarn No. Y18 Yl9 Y20 _ _ _ _ _ Croas-sectio~aL figure F}G.l FIG.7 FIG.8 ~ _ NoncondUcttiVe 4 89 90 ~0 Area _ _ ratio Conductive c~mpo~ent ~ 9 10 10 _ , ~ixtur~ component ~ 2(1~1) _ _, ___ Speci~ic resistance Q-cm 4X102 2X102 5X102 _ _ . _ _ _ ties Antistatic prop~rty kV 1.6 3.6 1.5 __ _ _ . _ Metal a~tasiv~min 31 35 4 property .
_ __ __ _ RemarXs invention Comparative _ __ Any of the yarns Y18~Y20 had a specific resist-ance of the order of 102 Q cm and exhibited good conductivity. The yarns Y18 and Y20 had a good antistatic property but the yarn Ylg whose conductive ~535i~

polymer component was not e~posed on the surface of the filaments had a poor antistatic property.
Further, the yarns Yl~ and Ylg had a decreased metal abrasive property, vhile the yarn Y20 showed a 05 considerably increased metal abrasive property and could not manufactured stably due to abrasion of thread guides.
Next, the yarns Yl~ and Ylg were respectively plied with a nylon-6 yarn of 2,600 deniers/140 filaments 10 and the plied yarns were crimped by texturiziny. Using the texturized yarn in every fourth course and only the nylon yarn in every three courses/ a tufted carpet (looped, the mixed ratio of the conductive filaments:
0.17%) was produced. A char~ed voltage of a human body 15 generated when a man putting on leather ~hoes ~alked on resulting carpet in a room at 25C with 20% R.~. was measured. The charged voltage of the carpet incorporat-ed with the yarn Y18 of the present invention was -2.1 kV. Xn contrast, that of the carpet incorporated 20 with the yarn Ylg, a sheath-core type composite filament yarn, was -4.3 kV and an electric shock was received from a grounded doorknob. For the purpose of compari-son, the charged voltage of human body of a carpet composed only of nylon was measured -9.2 IcV and the 2~ electric shock received from the grounded doorknob was so violent that a considerable fear was felt.

Claims (14)

1. A unitary electroconductive composite filament comprising:
(a) a non-electroconductive component composed of a first, fiber-forming, thermoplastic polymer, forming a sheath extending along the entire length of the filament, and (b) an electroconductive component consisting of an eloctroconductive core having a thickness of not less than 5 micrometers and an electroconductive path, being lapped in and extending lengthwise along said sheath, said core being composed of a mixture of at least one, second, thermoplastic polymer with inorganic electroconductive particles, said path having a composition the same as that of the core, said second thermoplastic polymers being poor in compatibility with said first thermoplastic polymer, said path being a thin portion extending laterally from a part of the periphery of said core, transversely through the sheath, up to or close to the outer circumference of the sheath, the outer end of said electroconductive path being discontinuously exposed on the outer surface of said filament in a direction extending lengthwise of said filament, the width of the exposed portions of said outer end of said path being not more than 1.5 micrometers.

2. A filament as claimed in claim 1, wherein, in cross-section, said electroconductive component has a tadpole-like shape consisting of a head forming the electroconductive core having a thickness of not less than 5 µm and a tail forming the electroconductive path.

3. A filament as claimed in claim 2, wherein said head occupies at least 60% of the cross-sectional area of the electroconductive component.

4. A filament as claimed in claim 1, wherein said exposed portions of said outer end of said electroconductive path are not more than 1.2 µm in width.

5. A filament as claimed in claim 1, wherein said exposed portions of said outer end of said electroconductive path are not more than 1 µm in width and extend not more than 50% of the entire length of the filament.

6. A filament as claimed in claim 1, wherein said electroconductive component occupies 3-40% of the cross-sectional area of the filament.

7. A filament as claimed in claim 1, wherein said electroconductive path has the same composition as the electroconductive core.

8. A filament as claimed in claim 1, wherein said electroconductive path comprises a mixture of said first, fiber-forming, thermoplastic polymer with the mixture composing the electroconductive cord.

9. A filament as claimed in claim 1, wherein said electroconductive component has a specific resistance of not more than 104 .OMEGA. - cm.

10. A filament as claimed in claim 9, wherein the specific resistance is not more than 102 .OMEGA. - cm.

11. A filament as claimed in claim 1, wherein said first, fiber-forming thermoplastic polymer is an organic synthetic linear polymer selected from the group consisting of nylon-6, nylon-66, nylon-12, nylon-610, polyethylene terephthalate, polyethylene oxybenzoate, polybutylene terephthalate, and copolymers and modified polymers thereof.

12. A filament as claimed in claim 1 whersin said second thermoplastic polymer contained in the conductive component is an organic synthetic linear polymer selected from the group consisting of polyethylene, polypropylene, polyoxymethylene, and copolymers thereof.

13. An antistatic fibrous article which comprises 0.01 5% by weight of a filament as claimed in claim 1.

14. A fibrous article as claimed in claim 13, which is a carpet.