NO127509B - - Google Patents

Description

Yarn with the ability to . to announce, desired,

antistatic properties of textiles or textile mixtures.

The present invention relates to new electrically conductive yarns. are useful for imparting antistatic properties to textile articles containing it.

It is well known that textile articles consisting of many synthetic yarns, e.g. Polyamide yarns, polyester yarns and acrylic polymer yarns tend to build up high static electrical charges during use. E.g. carpets made of such yarns and also other yarns, such as wool, tend to generate static charge when walked on, which not only results in shock to the person concerned, but also promotes soiling of the carpet.

It has now been proposed to remove such charges from ra; carpets

by incorporating metal, especially copper, wires or rust-free steel fibers into them, although the mechanical properties of such wires

and fibers are very different from textile fibers in general, and

the synthetic textile fibers in particular, problems arise in connection with their mixing and processing in ng-j.. as well as in the <r>' processing of the obtained products.

Conductive fibers are known,! which consists of a continuous phase of

a fibrous material through which a conductive material, e.g. carbon black or a finely divided metal is distributed as a dispersed phase. The use of such fibers in connection with ordinary, non-conductive fibers gives rise to to a greater or lesser extent similar disadvantages.

US Patent No. 3,206,923 describes viscose yarns which are determined

to create an antistatic effect by conducting charges to earth, e.g. to a conductive floor. The yarns are made conductive by impregnating them with cotton wool, and as this treatment significantly weakens the yarns, they are then reinforced by double twisting with non- conductive but stronger yarn, eg of cotton or a synthetic polymer Typically, equal numbers of conductive and reinforcing yarns are double-twisted together.

It has also been proposed to make electric heating elements by coating a non-conductive fiber with a conductive coating which may consist of a dispersion of iron oxide or a finely divided metal in a binder matrix. However, such elements are intended to carry relatively strong currents and are of a relatively heavy construction.

British patent no. 980,052 deals with electrically conductive fibers and woven textiles for use as heating elements or the like, where the textile as a whole, both the warp-bg/or weft threads or the individual filaments, from which these threads have been produced, are has been coated with and/or - impregnated with a conductive mixture consisting of, among other things; of carbon monoxide or solv particles. The relevant yarn has high denier, e.g. 4,800, and is composed of high denier filaments, e.g. 100.

It has also been proposed in US patent no. 2,302,003 to incorporate conductive fibers into carpets, such as short lengths of a conductive yarn, namely a cotton yarn that has been immersed in a liquid consisting of cotton wool and a rubber binder and applied. These lengths of yarn end at the surface of the carpet and extend to an electrically conductive background to dissipate static charges that develop on the surface. These fibers depend on the presence of the conductive background to be effective.

US Patent No. 2,473,183 describes heating elements primarily for use in electric carpets and the like, which consist of a conductive film of a plasticized vinyl resin containing a suitable amount of carbon black. Such a film may be self-supporting or it may form on the surface of a textile or on all or some of the individual yarns used in the textile. The formation of such a film on a yarn or textile will have a significant effect on its physical and general surface properties.

US patent no. 3,013,903 describes the formation on fibers and textiles of a layer of colloidal aluminum oxide, and then a top coating of an organic polymer containing sulfonic acid groups. Thus, a staple fiber, multifilament yarn or textile can be treated in this way as a whole and acquire various applicable properties including resistance to soiling and antistatic properties (the latter is presumably due to the hydrophilic properties of aluminum oxide, as it is not an electrical conductor in itself ). One such treatment, by its very nature, has a significant effect on the physical and

surface properties of the fiber or textile as a whole.

US patent no. 3,278,455 describes the production of conductive sheets for use as transformer plates in oil-filled transformers and consists of an insulating core of hard plates or the like which carries one copper foil or is a sprayed-on layer of copper or aluminum to the edges of which there is quickly a mixture consisting of oxide-coated copper or copper-alloy rich dispersed in an epoxy resin which is then cured to a hard, non-fusible state. It is clear that this process has no textile application.

Published Japanese Patent Application No. 8440/67 describes certain compositions which can be applied to fibrous materials, especially textiles, to make them electrically conductive and give them antistatic properties. However, there is no trace1 of applying the coating mixture to the individual, elementary components of the fibrous material.

It has now been found that yarns consisting of electrically conductive fibers of a specific degree of fineness and having certain other characteristics have the ability to spread electric charges from objects containing them, even if they are not in contact with a conductive background or another manager with high capacity, i.e. they are not in any way earthed, and moreover such yarns are for practical purposes indistinguishable from ordinary non-conductive yarns as far as their mechanical and textile properties are concerned, so that they do not give rise to any special difficulties in processing, and they do not affect substantially the treatment of objects containing them.

The invention relates to a yarn capable of imparting antistatic properties to textiles and textile articles containing the yarn, which mainly consists of electrically non-conductive threads and one or a small number of electrically conductive threads of a non-conductive base with a coating of a resinous matrix, in which there are dispersed fine particles of a conductive material, especially carbon black or finely divided solv, which threads have an electrical resistance not exceeding 2000 megohm per cm, and the yarn is characterized by the fact that the yarn is a multifilament yarn, where each of the conductive filaments consists of a carrier of a continuous organic synthetic filament with denier 5 - 50, with an electrically conductive coating having an average thickness of 0.3 15 microns . Preferably, the denier of the carrier is below 30, preferably 10-30.

The carrier may be any suitable chemical fiber consisting of a polymer such as nylon, a polyester, an acrylic, polypropylene, cellulose acetate or regenerated cellulose, and the coated filaments have been found to have the functional properties of the carrier filament. The term "functional properties of textile fibers" as used herein is generally intended to mean the mechanical properties whereby a fiber can be subjected to ordinary spinning, twisting, shrinking, weaving or knitting treatments and withstands such conditions as it would normally be subjected to during the processing steps as well as by use, i.e. such conditions as wear, tensile stress, bowing stress, repeated bowing, repeated stretching and relaxation, and repeated compression and relaxation, and furthermore be compatible and workable together with ordinary, organic textile fibres. Thus, they must be electrically conductive yarns and normally they will have a tensile strength of at least approx. 1 g/den., preferably at least 2 g/den., an elongation at break of at least 3%, preferably at least 10%, an initial modulus not exceeding 3000 kg/mm 2 , preferably not exceeding 2000 kg/mm 2 , and a the density of • below 2.5 g/cm 3 , preferably below 2.0 g/cm 3 , as well as satisfactory properties in the longitudinal direction, such as flexibility and chemical properties, such as the ability to resist the usual scouring , washing and dyeing treatments.

The electrically conductive coating can be formed on the carrier filament by applying to it a polymeric binder solution or emulsion in which finely divided solv and/or carbon black are dispersed, drying to form a solid coating, and if necessary curing the polymeric binder. The multifilament yarns of the invention can be produced by connecting a small number of ends, most advantageously one end, of the coated filament, which may be crimped or non-crimped, to a bundle of filaments, such as crimped nylon or polyester filaments, and then twisting the resulting yarn bundle . Optionally, the electrically conductive fiber may be connected to a bundle of unshrunk filaments, and the resulting bundle is then mechanically crimped and twisted.

The new yarns beyond their effect even if they are present^ioc-,*,_a the textile article in relatively small,quantities. F. eg.., now r,.de, in nn-,,..

a£»ivcoTicv/.oc» , iVT/s ns ,i;ii'3svxoq i?e ,i:Oi\'n %oa iWioq are worked in"the surface of a carpet they must be present, i,en. „

3b ^yr;r.i'^ is Job cc ,aaoiuii-io .^-r.rtap^i isixa .as»aaai>s»at.»i.2/a.i9n amount of at least O.Ol weight spoon. Although it is sometimes possible _f..

•io* -isa^MsrtspÆ- ciAsriOta^it.«l &c is.-, isjnzn&n? t>n*uij> try to achieve antistatic properties yourself, with.smaller amounts of er*. the effects often not stable. On the other hand,.when the quantity.. -in&Xm; ab v.ts>d i *J-3ionsp i i fins (t3p aeotiavas «.lo* *;>:ruii of electrically conducting fiber rises .from 2% to 10 yekts%riay.tar.;„ -nie- piXniw as^aBjCiafcnu rusand x r «i* m*viovn , ji*q^o.Tte|,-w the corresponding proportional improvement in antistatic; virk-,.;,. isp':i!baiirfada&f £&a i«£i* cninvsv .stfi.tqniYi* .{xuntviv.» , or^f: ning gradually after the latter value is reached. Therefore-shall„ •^53<4.>, life sj.voiXr?i>v 39)-. moa r3iil9r;(UJ9G o^ms isjrrfjoo. t>o from a practical point of view the electrically conductive, fiber anven-^.„:, c-yX.t r? fr».v.5 ...-iiJ-.M o <w n\o> lovte &-i*m:.- iijn£.ni 1 ortfctiuu 'www 10.1 des i" the carpet surface in an amount of O.Ol tilflo v ect s%, .and pr» trum -r a£n« on i rt at „ cn i ntns eq rtasl 5 £ '<*G2fi 2 fi!i>d is«^i.«^ya preferably between 6.05 and .2 wt%.. ,...Hr^,Crr r K-i.sv ei-tiv , isna rnøsq-'. v'- po -lepni^v-^r^rn-nsa sjjs^no^ That the electrically conductive filament used in the invention _-;0 bon .»-->;f"A£dbrodisacvnsa po -&nit>«nt )-2oj vn1'?,;, ^^;:^, ku'nne~resist shrink treatment, twisting, weaving-and the like-.^ nendé treatments were unexpected. Furthermore, that the incorporation„of .c.»b\c I .Io .-lenici éq ^li^s-nA^x-P:- n-3 -.u*. uv j^.m:.i>;.i t?1--only*one end of an electrically conducting monofilament in .a g.arn-r,.v •tame r.c- bfri.nd b«v a i -.tol no r.nso\p * jyfiuv uv^iii ..j W. bundle which can have a denier as high as 1000 to 5000 var, .full-•., r i^vo L^bom pi k-a-u-^oo :is ,# Oi JSitim mvan*.! jJiol ,^ constantly effective,- was surprising., Moreover, it became Sover.rja-.....,,- skende' found that only a few yarns in the textile item need-. moa [3v;<;>5 ,^mr>'.r> . S ::,abnlf > ):cr. •r.r- -.fj o,.. n-u-.-it! j.-^ be "electrically conductive yarn as described above. Usable.,.* -x-j'~i i.;os .\'.ila .. •:;•••» ^r» inOe 2 i> bon c> I 1 r.oq.-3:< v i7'.»p»# '?ofrw 1 U antistatic effects can 1 reality be achieved by placing -, ioin A U.y r:3r:vo :nof; .. as:\by'.s*ip-.-> ^taintsf^ pc the yarn according to the invention at intervals of up to 30. ,cen-. hours bg preferably up to approx. lo centimetres. Examples of carrier fibers that are particularly preferred from among others iyfU- r.AXfisdXc-qcXsir-bxiiisba cci -A.rrvio^ r;.=> ••i-.nst) awi^ = adhesion tii the conductive coating and mechanical, strength .is...... \«>I.'9Vk> vi<)2 -;r.£>bri.L-x iispieqaxp "is "tsij rie^.=.J.vu t ,!.i'JL<=Ji-,,,': 5" fibers "of synthetic linear polyamides, such as. nylon, 6 ,o.g.,66,...s-Findelt soiv and jonrok have been found to have advantages over furers, -nslqqo ^.^3 2.i3n-5Dr)jndmRJ.a..:Jn;K . x^oxrneoaso y^fn^J '---i '••!-' other conductive materials with respect to their. mots_tandsevne,.mot, .ionas X Ta ins -jiil .>5> ?>b.c i; Gid:.' f sav a-Mi..< j£;«»i:i ho.». scouring, washing and dyeing treatment and. climate conditions,

ns.N nies , rfa-rr.s t ia 9«3f«iSisvo .ts» vb ,9£)'?d j>i^wi;voj chemical resistance and electrical conductivity., Suitable._po.ly- ^ more binders include all the synthetic.resins./of...

zicr.tsiJ go ioin5?S5Slxlt«?asY-o«[ -^-i ^ nox^rt '>*o« acrylic, epoxy, phenol, urethane, melamine, urea^ . polyester rT^,,. 4 vinyl- and silicone-type, natural, and synthetic^rubbers-. and.f „cl:r f

-i: sfsc-nvx:*:• --sjl.^x vs Joi:a cv? nstu jj&nuaiuv 5fev wu,^«a!sci51 mixtures "of these. The special binder will; be selected, „ - in each individual case, taking into account such^e^gen- v,r> factors as adhesiveness to the carrier fiber , resistance to wear

ogqchemikaliefPhosndet^hardened^coating joint 'flexibility for*the <overt-rukne,lbæref iber. The liquid mixture which is used as the carrier may also contain additives, such as thickeners/antioxidants and modifiers for media flexibility. ^dvretre^^^and 1'er^dningmid'?Tfor° the xpolymeric^binder'.- "-Examples of suitable polymeric binders- -include the r-combinations --of the oil-soluble phenolic resins -:with chloroprene poly-ymererv styrene/butadiene copolymers, akx.y/loni'tri4f/butadiev'ymer Jog other synthetic rubbers $ the combinations 'of -a -epdoxyharprks of the bisphenol/epichlorohydrin type> .which^has' a - ■epoxyékVivaTérit pa 170 "to 250' with a polyamide resin, an epoxy-vegetabi 1 -sV^oi^jV^iie^^l^Vndé polyal^' kylensulf ld^-relati-vt-' low molecular polyurethane-ureas with end-standendé'- N^N-di substituted1 tfreylene groups3;'' kdmblhaVjbnen'of' a'' partiallyvf or sapet1 vinylichloride/vinyracéta^-copoly^ 6q one melamine-respic-ks modif i'sert,rmed,'n-butane61 -, 'and'combined with ethyl acrylate/sty pure/hydroxyethyl;acrylaf and' a ' mel am'i n'arpiks" modi f i seir t"' with n-butanol. •■•••■••■>-■ c

The quantity: of =-f ihdél sblv 'or/ driving smoke in the electrically praying cover will-;determine'-'-iédnihgsevneri'' for the fiTamentét'. Thus

the overcoat must contain at least 50% by weight of solvate and must be 5% in the case of beef. Vidéré is preferred out of .the point of view-stability and reliability of the 'conductivity at^'" t<y>kkelseri"fof the coating néf miristrdy7°micron'in'the case of kjonrok. Deni-bvre -limit "for r>tyklcéf'séti! ;of ^overcoating* '-and^mengdén i'"" overcoating of- = four-part^sblV^eries 'kjonrok! is determined according to their effect on the mechanical properties, especially of the filament flexibility jV;St-yrkén**åv -The cover' and attached tni ngen 'me f lom "the cover and the carrier. A coating that is too thick is not only unnecessary from the point of view of conductivity, but also undesirable from the point of view of flexibility. A coating that contains finely divided sblv as its electrically conductive material preferably has a thickness not exceeding 10 microns. Furthermore, coatings that contain more than 90% sblv or 60% jonrok usually lack strength and their adhesion to the support, and therefore tend to be easily separated from the support under the processing conditions and during use.

It is also to be noted that the electrically conductive yarns according to the invention are effective in reducing static charges not only when their electrical resistance is in the range of that of an ordinary conductor, but also when it is very high, up to 2000 m/h /cm, and also when they are present in the textile item in a very small amount. It is not easy to explain why this is so. However, usually it can be said that a static voltage above 1000 volts means a significant problem, although the actual amount of static electricity generated may be very small. It is believed that even in the case of yarns with high electrical resistance, local electrical breakdown occurs in the overcoat under such high voltages, and the electrostatic charge is easily dispersed by such effects as gaseous corona discharges, surface flashover and tracking and leakage, and cause cases thus accumulation of electrostatic charge. Furthermore, the dispersion of electrostatic charge over the electrically conductive filaments as well as their shielding effect appears to contribute to the antistatic effect.

The following examples illustrate the invention. The resistances were determined using an FM tester, model L-19-B and an automatic insulation ohmmeter, model L-68, manufactured by Yokogawa Electric Works, Japan, and firmness, elongation and initial Young's modulus were measured on a sample of 5 cm measured length with a stretching speed of 5 cm/minute. The electric voltage was measured using a collector-type potentiometer, model K-325, manufactured by Kasuga Electric Company, Japan.

Unless otherwise stated, parts and shares are by weight......

EXAMPLE 1 10 parts of finely divided solar flakes (average particle size 1.5 microns), 10 parts of nitrile rubber-phenol type adhesive (fixing substance content'24'%) and 10 parts of methyl isobutyl ketone were carefully mixed to give a paste, through which a 20 denier crimped nylon 6 monofilament was fast, after which the filament was fast through a slot to regulate the thickness of the cover. The monofilament was then cured by heating with an infrared lamp to obtain an electrically conductive monofilament (A) having an average electrically conductive coating thickness of 0.4 micron and an average resistance of 500 M.n/cm.

The electrically conductive filament thus obtained had the following fiber properties: a breaking strength of 4.0 g/den. (5.1 g/ den. calculated on the basis of the denier fineness of the carrier filament), an elongation at break of 40% and an original Young's modulus of 300 kg/mm 2, which thus shows that it has a breaking strength as well as bendability and flexibility that hardly differentiate separate from those for the carrier filament. The density of the filament was as low as 1.3 g/cm.

One end of the aforementioned monofilament was twisted into a crimped nylon yarn of 2600 denier/136 filaments and provides a yarn which, when incorporated into a carpet, provided a useful antistatic effect.

EXAMPLE 2

A 15 denier nylon 6 monofilament was passed through a paste similar to that described in Example 1 and then cured by heating to provide an electrically conductive filament like hair with an average coating thickness of 2.8 microns and an average resistance of 30 A/cm, a breaking strength of 3.1 g/den.

(5.6 g/den. on the basis of the denier unit of the carrier filament)",

an elongation at break of 45%, originally Young's modulus of 260 kg/mm 2 and a density of approx. 1.7 g/cm 3. This was incorporated

in a crimped nylon yarn as in example 1.

EXAMPLE 3

The electrically conductive monofilament produced in example 2 was twisted with a 2-strand twisting yarn produced from worsted yarn no.

16 by adding a single string of the former to dispute handling none of the latter. The resulting yarn was incorporated with two strands of plain 2-ply No. 16 worsted yarn, which contained no electrically conductive filament. The three strands of yarn were laid parallel and were made into a continuous yarn, which was used in pole var-

neat in a Wilton rug in a ratio of 1:9, and the rest of the pol-

the warps were similar except that they contained no elec-

tric conducting filaments.

Claims (3)

1. Yarn with the ability to impart desired antistatic properties to textiles or textile items that contain holds the yarn and which consists mainly of electrically non-conductive threads and one or a small number of electrically conductive threads consisting of a non-conductive base with a coating of a resinous matrix in which fine particles of a conductive material are dispersed, in particular jonrok or finely divided solv, which wires have an electrical resistance not exceeding 2000 megohm per cm, characterized by. that the yarn is a multifilament yarn where each of the conductive filaments consists of a carrier of a continuous organic, synthetic filament with denier 5 - 50 with an electrically conductive coating which has an average thickness of 0.3 - 15 microns. 2. Yarn as stated in claim 1, characterized in that the conductive cover is. 0.3 10 microns thick and contains 50-90 wt% solv. 3. Yarn as specified in claim 1, characterized in that the conductive coating is 0.7 - 15 microns thick and contains 5 - 60% cotton wool.