GB1562461A

GB1562461A - Mixtures of synthetic fibres or filaments containing carbon black

Info

Publication number: GB1562461A
Application number: GB36519/77A
Authority: GB
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1976-09-02
Filing date: 1977-09-01
Publication date: 1980-03-12
Also published as: PT66967A; LU78061A1; IE45577B1; AT370452B; ES462035A1; DE2639499A1; DD135219A1; FR2363646B1; DK390177A; NL7709654A; IE45577L; PT66967B; FR2363646A1; DE2639499C2; BE858277A; ATA627777A; CH619339GA3; CH619339B

Abstract

The dark colour of antistatic, carbon black-containing synthetic fibres or yarns can be made to disappear visually by using carbon black-containing fibres that are composed of acrylonitrile polymers or copolymers and have a boil-out shrinkage of 10 to 70%, in particular 20 to 50%, and mixing 0.1 to 20% by weight of those fibres with 99.9 to 80% by weight of carbon black-free fibres composed of polyamide, polyester, polyalkene or poly(mod)acrylics. On bringing about the boil-out shrinkage, for example in tufted material, the dark colour of the carbon black-containing fibres is then hidden.

Description

(54) MIXTURES OF SYNTHETIC FIBRES OR FILAMENTS CONTAINING CARBON BLACK (71) We, BAYER AKENGESELL- SCHAFT, a body corporate organised under the laws of the Federal Republic of Germany, of 509 Leverkusen, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to fibre and filament mixtures consisting of high-shrinkage synthetic fibres or filaments containing carbon black and standard synthetic fibres or filaments free from carbon black of, for example, a polyamide, polyester, polyalkylene or poly(mod)acrylic, to a process for their production and to textile artides produced from them.

It is generally known that synthetic fibres or filaments of polyacrylonitrile, polyamide, poly esters or polyalkenes and sheet-form textiles produced from them have the undesirable property of becoming electrostatically charged and this property restricts their use in the tex tile or industrial sector. A troublesome charge such as this is developed when the surface re sistance of the fibres amounts to more than 1()12 ohms, as measured at 230C/50% relative humidity. A variety of different measures have already been proposed to obviate this disadvantage. In many cases, attempts are made to improve the conductivity of the fibres or filaments by subjecting them or the textiles produced from them to a surface treatment with antistatic preparations. Unfortunately, the antistatic effect obtained in this way is often not permanent.

Another widely used method is to mix the fibre or filament substrates with specific conductivity-improving polymers which almost always contain polyethylene oxide units as their effective component, and subsequently to spin the mixtures from the solution or melt.

For producing antistatic fibres or filaments of the type in question, this involves different processing technology in relation to the production of non-modified fibres or filaments and, hence, additional effort.

A recent process for reducing the electrostatic charging of sheet-form textiles, such as floor coverings for example (cf. for example Chemiefasern/Textilindustrie, January, 1976, page 14), is based on the addition of metal fibres to normal fibres of the above-mentioned type and spinning them together, but unfortunately this frequently gives rise to considerable difficulties. The high price of the metal fibres is also a certain obstacle, as also is the deterioration in light colours affecting the textile articles produced from the mixture.

One relatively well established method of imparting high surface conductivity to polymeric systems is to add carbon black to them before they are processed. Examples are thermoplastic materials or elastomers containing additions of carbon black, such as for example poly(ethylenevinylacetate), natural rubber, styrene - butadiene rubber, polychloroprene, nitrile rubber, etc. The quantities of carbon black used may make up as much as 50% by weight of the mixture of solids (C7z.

for example Advances Chem.Ser. 134 (1974), pages 171-183).

Filaments modified with carbon black are already in use in the textile sector. In their case, improved antistatic behaviour is gener ally obtained. However, it is important for any textile application of filaments modified with carbon black to avoid an unfavourable visual impression caused by the modification of the articles with carbon black. Although carbon-jacket filaments (epitropics) are known (Textile Manufacturer, July 1974, pages 1923), they can only be added to filament yarns or normal polyester or polyamide and in addition, lead to an unfavourable appearance of light colours in the case of solid-colour yarns and fabrics. In addition, filaments consisting of a carbon core/polyamide jacket have been processed in admixture with polyamides (Chemiefasern/Textilindustrie, January, 1976, page 14).In this case, too, however, the addition is confined solely to filament yarns (BCF).

It has now been found that mixtures of 5 to 25% by weight of carbon black and 95 to 75% by weight of an acrylonitrile copolymer, when spun together from a solvent which dissolves the acrylonitrile copolymer, gives filaments or fibres which, in their fully shrunk state and depending upon the type and quantity of carbon black used, have permanent surface resistant of 1011 to 103 ohms, as measured at 230C/50uio, relative air humidity.It has also been found that these acrylic fibres or filaments containing carbon black need only be mixed in a proportion of from 0.1 to 20% by weight of the total mixture with other filaments or fibres, for example of poly(mod)acrylic, polyamide, polyester or polyalkene, in order to produce sheet-form textiles, such as floor coverings, woven and knitted fabrics, which have adequate antistatic properties for practical purposes.

In addition, it has surprisingly been found that the dark spots in the textile article caused by the acrylic fibres or filaments containing carbon black can be rendered less noticeable or even completely avoided by using shrinkable carbon-black-containing fibres or filaments.

The reason for this is that, whereas mixture effects are obtained, as expected. by adding normally shrinking acrylic fibres or filaments containing carbon black, there is quite un expectedly very little, if any, change in the optical effect in cases where corresponding medium-shrinkage or high-shrinkage fibres or filaments are used, providing measures are taken to ensure that these carbon-black-con taming medium-shrinkage or high-shrinkage fibres and filaments are able to shrink fully in the textile article, Thus, textile products pro duced from fibre yarn or filament yarn mixtures of this kind, such as for example floor coverings, woven and knitted fabrics and also non-wovens, do not show any streakiness after a shrinkage-initiating treatment such as, for example, boiling, dyeing, streaming, printing, latexing and any other finishing process taking place at elevated temperature (approximately 100cm). In particular, this makes it possible to obtain light colours without in any way detracting from the visual appearance of the textile.

It is clear that this principle mentioned in regard to acrylic filaments in particular applies equally to any shrinkable synthetic fibres or filaments containing carbon black.

Accordingly, the present invention provides fibre and filament mixtures consisting of from 0.1 to 20% by weight and preferably of from 0.2 to 5% by weight of carbon-black-contain- ing synthetic fibres or filaments having a boiling-induced shrinkage of from 10 to 70%, and of from 99.9 to 80 Co by weight and preferably of from 99.8 to 95ego by weight of synthetic fibres or filaments of polyamide, polyester, poly(mod)acrylic or polyalkene.

The quantity of carbon black in the filaments or fibres containing carbon black generally amounts to between 5 and 25%, by weight and preferably to between 10 and 20 )o by weight, based on the total solids content.

In order to obtain as good as possible a turnout of the finished textile, the boiling-induced shrinkage of the filaments or fibres containing carbon black amounts to between 10 and 70% and preferably to between 20 and 50%.

By the addition of carbon black, the surface resistance of the fully shrunk fibres or filaments is reduced from an original level of more than 1011 ohms to values of from about 103 to 1011 ohms (as measured at 230C/50"/, relative humidity after 10 washes in accordance with DIN 54 345, sheet 1).

The carbon-black-containing filaments or fibres may consist of polyamides, of polyesters, of polyalkenes, but preferably of acrylonitrile(co)polymers.

The invention is described by way of example in the following with reference to the production and processing of high-shrinkage (mod)acrylic fibres containing carbon black.

To produce the acrylic or modacrylic fibres containing carbon black, carbon black is mixed with and finely dispersed, by high-speed stirring, in a solution of an acrylonitrile copolymer, optionally in the presence of small quantities of an emulsifier to facilitate dispersion.

The solution is then spun under the known conditions of dry spinning or wet spinning.

On the other hand, it is also possible to prepare a separate mixture of the total quantity of carbon black required and part of the acrylonitrile copolymer required in the corresponding solvent, to filter the suspension and then to add a stream thereof in the correct ratio to the dissolved residual quantity of polymer either just before the spinneret through a static mixer or even in a kettle. Suitable solvents are any solvents known to the expert such as, for example, the preferred solvents dimethyl formamide and dimethylacetamide.

Solution promoters are not necessary. The tows are then processed into filaments in known manner by washing out the solvent drawing, preparing, drying, crimping and steaming, or by additional process steps into fibres. In order to obtain final shrinkage levels of from 10 to 70% low dryer temperatures are applied and only very little steam is admitted during the steaming process, or alternatively the steamer is operated as a drying unit.

The quantity and type of carbon black used determine the surface resistance of the modified acrylic fibres or filaments. It is, of course, preferred to use carbon blacks which specifically show an improved conductivity in relation to other carbon blacks, although it is also possible to use other types of carbon black. The carbon blacks generally used have an average particle diameter of from 10 to 60 mp, preferably from 15 to 40 m,u, and a surface (N2) of from 60 to 300 m2/g, preferably from 90 to 260 m/g.

The quantity of carbon black used should amount to at least 5oxy by weight and to at most 25 by weight, based on the sum total of the solids used, because it is only with quantities within this range that the intrinsic conductivity of normal fully shrunk acrylic fibres or filaments is increased from approximately 1011 Siemens to between 10-11 and 10-3 Siemens, leaving the minimum textile values (strength, elongation, etc.) intact.

Any acrylonitrile copolymers known to and used by the expert for the production of synthetic acrylic fibres or filaments may be used for the purposes of the invention.

The acrylonitrile copolymers in question are primarily substrates of which at least 85 by weight consist of acrylonitrile and which, in addition, contain (meth)acrylates, vinyl carboxylate, (meth)allyl carboxylates, (iso)butenyl carboxylates, maleates, fumarates, (meth)acrylonamides and N-substituted derivatives, vinyl ethers, styrene and derivatives, alkenes, methacrylonitrile, also dye-receptive additives such as, for example, (meth)acrylic acid, itaconic acid, maleic add, vinyl-, (meth)allyl-, styrene - sulphonic add, sulphalkyl(methS acrylates, vinyl-, (meth)- allyl - phosphonic add or N - sulphoalkyl(meth)acrylamide.

Since the total content of acrylonitrile is theoretically reduced by the addition of carbon black, the total acrylonitrile content of the fibres or filaments modified with carbon black can easily be less than 85 % by weight, depending upon the quantity of carbon black added and the type of acrylonitrile copolymer used.

It is, of course, also possible to use acrylonitrile copolymers with an acrylonitrile content of far less than 85% by weight, i.e.

so-called modacrylics, for example those of acrylonitrile or vinyl or vinylidene halide with acrylonitrile contents of 60 or 40% I/o by weight.

The shrinkage level of the types containing the carbon black may be favourably influenced in particular by the comonomer content of the substrate.

When spinning these fibres from carbon black/polymer mixtures the spinning velocity advantageously is from 15030(} m/min, pre ferably 200 m/min and the of stretching ratio is from 1:1.8 to 1:3.0, preferably 1:10- 1:2.5.

These carbon black acrylic fibres or filaments are permanently antistatic, even after repeated washing, with surface resistance values of from 103 to 101l ohms in their fully shrunk state, as measured at 230C/50"/, relative air humidity in accordance with DIN 54 345, sheet 1.

For producing other high-shrinkage synthetic fibres or filaments containing carbon black, it is possible to use, for example, polycaprolactam, polyhexamethylene adipic amide, polyamino undecanoic acid, poly - (isophthaloyl m - phenylene diamide) polypyrrolidone, polyethylene glycol terephthalate, polycyclohexane 1,4 - dimethylol terephthalate, polybutvlene glycol terephthalate, polypivalolactone, poly (1 - hydroxyethoxy - 4 - carboxy) - benzene, polyethylene or polypropylene.

Boiling-induced shrinkage levels of more than 50% may be obtained particularly easily by using polyesters or mixed polyamides as the fibre or filament substrate.

In order to obtain textile articles, preferably floor coverings, but also knitted fabrics, woven fabrics and non-wovens, with inclusion of these special fibres or filaments, spinning fibre or filament yarn mixtures are prepared from 99.9 to 80 ,ó by weight of aliphatic or aromatic polyamide, polyester, poly(mod)acrylic or polyalkene fibres or filaments and from 0.1 to 20% by weight of the high- shrinkage carbon black-containing synthetic fibres or filaments.After a shrinkage-initiating treatment, such as the standard and necessary finishing processes, for example dyeing, the sheet-form textiles produced from these filament yarn or spinning fibre mixtures by conventional textile processes are in no way affected in their appearance by the presence of the medium-shrinkage or high-shrinkage black fibres or filaments fully shrunk in the finished article, whereas normalffhrinkage fibres or filaments containing carbon black are noticeable in the finished article.

If desired, antistatic additives may also be used during the finishing, if any, of the particular textile constructions. Examples of the fibres or filaments used as the main constituent of the fibre or filament mixtures are fibres or filaments of poly - e - caprolactam, polyhexamethylene adipic amide, polyaminoundecanoic acid, polypyrrolidone, poly(iso - phthaloyl m - phenylene diamide), polyethylene glycol terephthalate, polycyclohexane - 1,4 - dimethylol terephthalate, polybutylene glycol terephthatlate, polypivalolactone, poly(l hydroxyethoxy - 4 - carboxybenzene), polyethylene, polypropylene, poly(acrylonitrile methacrylate), poly(acrylonitrile vinylacetateh poly(acrylonitrile vinylidene chloride) or poly (acrylonitrile vinyl chloride).

Poly - e - caprolactam, polyhexamethylene adipic amide, polyethylene glycol terephthalate, polycyclohexane - 1,4 - dimethylol terephthalate, poly(acrylonitrile methyl acrylate) or polypropylene are preferably used.

The finished textile articles obtained from the fibre or filament mixtures show the properties characteristic of the substrate fibres or filaments such as, for example, textile-technological data, utility values, gloss, appearance, dyeability etc. and, in addition, are permanently antistatic. In the case of floor cover ings for example, this is reflected in the fact that any one walking over a floor covering, even in rooms with low air humidity, will feel no adverse effects, for example electrical shocks, as a result of electrostatic charging. For example, individual charges of from 200 to at most 1800 volts are measured in accordance with DIN 54 345, sheet 2, on velvet-pile carpets produced in this way and provided with an antistatic reinforcing finish.With other textile articles such as knitted pullovers for example, the permanent antistatic finish prevents the familiar unpleasant effects of charging and discharging such as, for example, crackling and sparking, during dressing and undressing.

Another advantage is that these permanently antistatic articles can also be dyed in light colours. Another feature worth mentioning, especially in regard to floor coverings produced in accordance with the invention, is that their sensitivity to water stains is no higher than that of floor coverings consisting entirely of the normal synthetic fibres and filaments mentioned here.

The carbon black content of the fibres/ filaments may be indirectly determined by elemental analyses. In the case of carbon-blackcontaining (mod)acrylic fibres for example, their nitrogen content is determined and com- pared with the corresponding value of fibres of the same type, but free from carbon black.

The carbon black content is obtained by calculating the difference.

In order to determine boiling-induced shrinkage, 10 individual capillaries are fastened at their ends to clips and are vertically suspended, the capillary length being determined.

They are then immersed in boiling water for 2 minutes, after which their length is remeasured. The difference between the original length and the final length is calculated as a percentage of the original length. The measurement is made 10 times and the results are averaged out.

In the case of fibres, filaments, yarns and sheet-form textiles, the antistatic effect is tested by measuring the electrical resistance values in accordance with DIN 54 345, sheet 1, and, in the case of floor coverings, additionally in accordance with DIN 54 345, sheet 2.

The textile properties, the utility values of the textile articles and also the fastness values (fastness to light and fastness of dye finishes) are determined in accordance with the known test specifications. Sensitivity to water stains is determined as follows: 50 ml of desalted water are poured onto a carpet, followed after complete drying in air by evaluation on the grey scale according to DIN 54001.

The production of the carbon-black-containing antistatic acrylic fibres and filaments, which are subsequently mixed with polyamide, polyester and polyacrylic fibres and processed into textile articles, is described in the following.

EXAMPLE 1 a) Preparation of a carbon black starting mixture 18.2 kg of dimethyl formamide (DMF) and 3.1 kg of a commercial-grade conductive carbon black, of the type used for electrically conductive lacquers and plastics, with an average particle size of 23 rn and a specific surface area of 150 m2/g (Corax L, a produce of Degussa, Frankfurt-on-Main) (Corax is a Trade Mark) were vigorously stirred for 24 hours while cooling. Thereafter, 11.3 kg of a 29.5% by weight solution of an acrylonitrile copolymer in DMF were added to this suspension, followed by stirring for another 3 hours without cooling.The acrylonitrile co polymer consisted of 94% by weight of aaylonitrile, 5.5% by weight of methylacrylate and 0.5% by weight of sodium methallyl sulphonate and had a K-value of 83 (Fikentscher, Cellulosechemie 13, 1932, page 58). In order to remove swollen particles, this mixture was forced through a cloth-covered filter press.

b) Dry spinning 15.1 kg of the filtered starting mixture, 4.7 kg of the above acrylonitrile copolymer, 7.1 kg of DMF and 0.1 kg of isononyl phenol polyglycol ether were heated for 2 hours to 800C to dissolve the polymer. For spinning, the suspension was pumped through a heat exchanger in which it was heated to approximately 1300C, to a spinneret containing 90 bores each with a diameter of 0.25 mm. The spinneret was situated at the upper end of a 4.5 metres long spinning duct with a diameter of 280 mm. To remove the solvent from the filaments leaving the spinneret, the duct was heated to 2100C and exposed to a stream of hot air (3800C) flowing at a rate of 40 m3/h. The filaments were taken off at 180 n/minute and wound into package form. The spinning denier was 32 dtex.The tow was stretched in a ratio of 1:2.3 in hot water (700C) and the solvent adhering to it was washed out The tow was then prepared, dried to 700C in the absence of shrinkage, crimped and cut into fibres 150 mm long. The fibres were then freedfi frorn residual moisture by blowing with air.

The fibres showed the following properties: Denier: 17.7 dtex (determined by weighing out) Carbon black content (determined by N analysis): 18.4% by weight Boiling-induced shrinkage: 45% Surface resistance of the fully shrunk fibres (after 10 washes): 7x103 ohm.

To produce filaments, the same procedure was adopted and a crimped tow was obtained.

c) Production of a velvet-pile fabric A yarn (count 3.8/1) was spun from a mix ture of 0.5% by weight of the above < lescribed fibre with 99.5% by weight of a nylon-6 fibre with a denier of 20 dtex. A semiworsted yarn, in which the component fibres were homogeneously mixed, was readily obtained by conventional worsted-spinning techniques without any additional aids. A carpet with a pile weight of 600 g and a pile depth of 6 mm was produced from this yarn in a 1/8" tufting machine.The velvet-pile carpet thus produced was dyed a very light beige with a combination of standard acid dyes, the shrinkage of the carbon-black containing fibres also being initiated during dyeing, and was then coated on its back with a standard stabilising composi tion and with a foam, both based on SBR latex, 4% of a standard antistatic agent having been added to the precoating compound to improve its intrinsic conductivity. Evaluation of the carpet did not reveal any deterioration in its optical appearance attributable to the presence of black fibres. Antistatic behaviour: individual charges of less than 500 volts were measured.

Comparison Example For comparison with the above-mentioned floor covering, a carpet of the 20 dtex nylon-6 fibre was produced under exactly the same conditions, except that the fibre according to the invention was not added. Evaluation of this carpet revealed an optical appearance en tirely identical with that of the above-mentioned floor covering. Testing of the fastness values and utility values of both carpets also produced entirely identical values, neither carpet being sensitive to water stains. Antistatic behaviour; individual charging values > 7000 volts.

In order to test the antistatic effect for permanence, both carpets were subjected to a continuous walking test over a period of 3 months. Individual charging values after this period: Carpet of Example 1: < 400volts Carpet of the Comparison Example: > 6500 volts EXAMPLE 2 a) Starting mixture An acrylonitrile copolymer/carbon black mixture was initially prepared in the same way as in Example 1 using the same polymer. The carboa black used was of the type which is also used inter alia for dyes, paper, carbon paper, etc., with an average particle size of 29 m,u and a surface of 96 m2/g (Printex 140, a product of Degussa, Frankfurt-on-Main) (Printex is a Trade Mark).

b) Spinning 17.6 kg of the filtreed carbon black starting mixture, 7.8 kg of DMF, 5.2 kg of the acrylonitrile copolymer characterised in Example 1 and 0.1 kg of the polyglycol ether mentioned in Example 1 were vigorously stirred for 2 hours at 80 C. As in Example 1, the suspension was pumped to a spinneret with 96 bores, each 0.25 mm in diameter, which was situated at the upper end of an 8.5 metres long duct with a diameter of 280 mm. The duct was heated to 1700C, the amount of air flowing through it amounted to 40 m3/h and the temperature of the air was 3000C. The filaments were run off at 200 m/minute and wound into package form. The tow was processed into fibres under the same conditions as in Example 1.

The fibres had the following properties: Denier: 15.5 dtex Cut length: 150 mm Carbon black content: 18.8 by weight Boiling-induced shrinkage: 41% Surface resistance of the fully shrunk fibres (after 10 washes): 5x 108 ohms.

c) Production of a tufted article A mixed yarn (count 3.5/1) was produced from a mixture of 3% of the fibre described in b) with 97% by weight of a polyacrylonitrile fibre (94% of acrylonitrile, 5.5% of methyl acrylate, 0.5% of sodium methallyl sulphon ate) with a denier of 17 dtex, and was pro cessed into a tufted article with a pile weight of 850 g/m2 and a pile depth of 10 mm. The polyacrylonitrile fibre had been previously flock-dyed an "olive" colour with standard basic dyes. It was latexed (in the same way as described in Example 1), during which the shrinkage of the carbon-black-containing fibre was initiated, and coated. Visual evaluation: no noticeable black fibres. Antistatic behaviour: individual charging values < 1000 volts.

Comparison Example For comparison, a tufted article was pro duced under the same conditions from a yarn consisting entirely of polyacrylonitrile with a denier of 17 dtex. Except for the antistatic behaviour, the tests results were identical with those of Example 2: individual charging values > 5000 volts.

EXAMPLE 3 52.8 kg of an acrylonitrile copolymer/car bon black starting mixture prepared in the same way as in Example 2, 30.4 kg of DMF and 17.6 kg of the repeatedly mentioned acrylonitrile copolymer were vigorously stirred for 3 hours at 800C. For spinning, the suspension was pumped through a heat ex changer, in which it was heated to 1300C before entering the spinneret, to the spinneret containing 180 bores, each with a diameter of 0.3 mm. This spinneret was situated at the upper end of the spinning duct used in Example 2 which was heated to 1700C and through which flowed 40 m3/h of air at a temperature of 290cm. The filaments were run off at 200 mfminute and wound into package form. The spinning denier amounted to approximately 20 dtex.As already repeatedly mentioned, further processing was carried out after stretching in a ratio of 1:2.5 by wash.

ing, preparation, drying at 65CC in the absence of shrinkage, crimping, cutting and blowing with air.

The fibres had the following properties: Denier: 7.9 dtex Cut length: 100 mm Carbon black content: 17.1% by weight Boiling-induced shrinkage: 39% Surface resistance of the fully shrunk fibres (after 10 washes): 2x109 ohms.

A varn (count 6/2) was spun from a mixture of 1% by weight of this fibre and 99% by weight of nylon-6 fibre (12 dtex). A floor covering with a pile weight of 720 g and a pile depth of 7 mm was produced from this twisted yarn, in which the two fibres were homogeneously mixed. It was dyed in the same way as described in Example 1, the shrinkage of the carbon-black-containing fibre being released during dyeing. However, the back of the floor covering was stabilized by coating with an SBR latex to which no antistatic agent had been added for increasing intrinsic conductivity.

The optical appearance of the floor covering was also not impaired by the presence of the black fibre. Antistatic behaviour: individual charging values < 3800 volts.

Comparison Example For comparison with the above-mentioned floor covering, a carpet was produced under exactly the same conditions from the 12 drex nylon6 fibre. Antistatic behaviour: individual charging values > 120Z volts.

EXAMPLE 4 (does not correspond to the invention) 14.2 kg of a starting mixture of carbon black and acrylonitrile copolymer prepared in the same way as in Example 2, 9.9 kg of DMF, 5.9 kg of the acrylonitrile copolymer described in Example 1 and 0.05 kg of the aromatic polyglycol were stirred for 2 hours at 800C. This was followed by spinning in the same way as described in Example 2 The tow was streched in a ratio of 1 2.5 in hot water, after which the DMF was washed out with hot water. The tow was then prepared and dried at 1300C with 20% permitted shrinkage The tow was then crimped, cut and briefly treated with superheated steam in order to remove the remaining residual shrinkage.

The fibres showed the following properties: Denier: 16.5 dtex Cut length: 150 mm Carbon black content: 15.1two by weight Residual shrinkage:1 lA/, Surface resistance of the fully shrunk fibre (after 10 washes): SxlO'" ohms.

The yarn (count 3.8/1) was spun from a mixture of 5% by weight of the described fibre and 95% by weight of a- nvlon-6 fibre.

The tufted article produced with a pile weight of 600 g/m2 and a pile depth of 6 mm was dyed dark red and provided with the same back finish as described in Example 3. Visual evaluation: the non-shrunk black fibres are clearly noticeable. The mixture effect obtained could possibly be of interest. Antistatic behaviour: individual charging values: < 2200 volts. With the same back finish as in Example 1: individual charging values < 300 volts.

Comparison Examples For comparison with the above-mentioned floor covering, a carpet was produced under otherwise the same conditions from the 20 dtex nylon fibre. Antistatic behaviour: individual charging values: > 11,000 volts ( finish as in Example 3). After the same back finishing treatment as in Example 1, the individual charging values amounted to > ó500 volts.

EXAMPLE 5 20.1 kg of the acrylonitrile copolymer/car bon black starting mixture produced in accordance with Example 1, 15 kg of the same acrylonitrile copolymer as in Example 1 and 35 kg of DMF were vigorously stirred for 4 hours at 800C. For dry spinning, the suspension was pumped through a heat exchanger, in which it was heated to 1200C, to a 180-bore spinneret with individual bore diameters of 0.25 mm.

The spinning duct was 8.5 metres long and 280 mm in diameter. The duct temperature was adjusted to 1800C and air heated to 3000C was passed through the duct at a rate of 40 m3/h. The filaments were run off at 200 m/minute. The tow was stretched in a ratio of 1:3.0 in hot water, after which the solvent adhering to it was washed out. The tow was then prepared, dried in the absence of shrinkage at 700C, crimped, cut into fibres 100 mm long and 60 mm long and the residual moisture in the fibres was removed by blowing with air.

The fibres showed the following properties: Denier 3.5 dtex Carbon black content: 9 8(o by weight 131Oiling-induced shrinkage: 37% Surface resistance of the fully shrunk fibres (after 10 washes): 6X10 ohms.

a) Production of a tufted article A yarn (count 2.8/1) was spun from a homogeneous mixture of 2% by weight of this fibre (cut length 100 mm) and 98 by weight of a polycyclohexane dimethylol terephthalate fibre with a denier of 6.7 dtex. A tufted carpet with a pile weight of 850 g and a pile depth of 10 mm was produced on a 5/32" tutting machine. The carpet was then dyed a light Berber shade with a standard combination of dispersion dyes in the presence of a carrier, the shrinkage of the carbon-blackcontaining fibres being initiated during dyeing.

The carpet was then stabilised and coated in the same way as described in Example 1. The black component fibre was not noticeable on evaluation. On the contrary, a completely uniform harmonious optical impression was obtained. Antistatic behaviour: individual charging values < 800 volts.

Comparison Example For comparison, a floor covering was pro duced under otherwise the same conditions from a cyclohexyl dimethanol terephthalic fibre with a denier of 6.7 dtex which had not been mixed with the fibre according to the invention. Antistatic behaviour: personal charging values > 500 volts.

b) Production of a knitted fabric After the production of a homogeneous fibre mixture, a mixture of 1% by weight of the described fibre and 99% by weight of a polyacrylonitrile fibre (dtex 3.3, 60 mm) with the same composition as in Example 2, which had previously been flock-dyed a "gold" shade, was spun by 3-cylinder spinning into a yarn (count 28/2) which was made up into a dense knitted fabric.

Visual assessment after fixing in the usual way (steaming), during which shrinkage of the carbon-black-containing fibre was initiated, revealed a completely uniform colour turnout.

In other words, the optical impression was not impaired by the black component fibres.

Antistatic behaviour: a surface resistance of 6x 10lo ohms was measured after ten domestic washes.

Comparison Example For comparison, a knitted fabric was produced under exactly the same conditions from a polyacrylonitrile fibre to which the fibre according to the invention had not been added.

Antistatic behaviour: surface resistance (after 10 domestic washes) > 1013 ohms.

EXAMPLE 6 A tufted carpet produced in accordance with Example 1 was not piece-dyed, but instead was screen-printed in the usual way (four colour printing: green/olive/brown/ white). The shrinkage of the carbon-blackcontaining fibre was initiated by the necessary steaming process.

Visual assessment: uniform optical impression, no black fibres noticeable. Antistatic behaviour: individual charging values < 500 volts.

Comparison Example Individual charging values of > 4800 volts were measured on the tufted carpet produced under otherwise the same conditions from nylon-6 fibre (20 dtex) to which the fibre according to the invention had not been added.

EXAMPLE 7 1% by weight of the crimped tow produced in accordance with Example 1 (individual denier dtex 18) was doubled with 99% by weight of a nylon-6 filament yarn of dtex 2670 f 126. The mixture of both filament yams produced in this way was wound into package form and subsequently processed under the normal con editions for BCF yarns (bulked continuous filament) into a loop pile carpet with a pile weight of 500 g and a pile depth of 5 mm.

After winch vat dyeing in a light beige colour, during which the carbon-black-containing acrylic fibre was fully shrunk, the carpet was stabilised (as described in Example l) and coated.

Visual evaluation: uniform appearance, no black filaments noticeable. Antistatic haviour: individual charging values < 700 volts.

Comparison Example Personal charging values of the comparison carpet produced without the fibre according to the invention, but under otherwise exactly the same conditions: > 5300 volts.

WHAT WE CLAIM IS:- 1. A fibre or filament mixture comprising from 0.1 to 20iso by weight of synthetic fibres or filaments containing carbon black and having a boiling-induced shrinkage of from 10 to 70%, and from 99.9 to 80% by weight of synthetic fibres or filaments of polyamide, polyester, polyalkylene or poly(mod)acrylic.

2. A fibre or filament mixture as claimed in Claim 1, wherein the carbon black content of the synthetic fibres or filaments containing carbon black is from 5 to 25% by weight, based on the sum total of solids.

3. A fibre or filaments mixture as claimed in Claims 1 or 2, wherein, in their fully shrunk state, the synthetic fibres or filaments containing carbon black have a surface resistance of from 103 to 10" ohms, as measured after 10 washes and at 230C/50% relative humidity in accordance with DIN 54 345, sheet 1.

4. A fibre or filament mixture as claimed in any one of Claims 1 to 3, wherein the synthetic fibres or filaments containing carbon black are (mod)acrylic fibres or filaments.

5. A fibre or filament mixture as claimed in any one of Claims 1 to 4, wherein the fibres or filaments not containing carbon black are fibres or filaments of poly - - caprolactam.

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Claims

**WARNING** start of CLMS field may overlap end of DESC **.

fibre with a denier of 6.7 dtex. A tufted carpet with a pile weight of 850 g and a pile depth of 10 mm was produced on a 5/32" tutting machine. The carpet was then dyed a light Berber shade with a standard combination of dispersion dyes in the presence of a carrier, the shrinkage of the carbon-blackcontaining fibres being initiated during dyeing.

The carpet was then stabilised and coated in the same way as described in Example 1. The black component fibre was not noticeable on evaluation. On the contrary, a completely uniform harmonious optical impression was obtained. Antistatic behaviour: individual charging values < 800 volts.

Comparison Example For comparison, a floor covering was pro duced under otherwise the same conditions from a cyclohexyl dimethanol terephthalic fibre with a denier of 6.7 dtex which had not been mixed with the fibre according to the invention. Antistatic behaviour: personal charging values > 500 volts.

b) Production of a knitted fabric After the production of a homogeneous fibre mixture, a mixture of 1% by weight of the described fibre and 99% by weight of a polyacrylonitrile fibre (dtex 3.3, 60 mm) with the same composition as in Example 2, which had previously been flock-dyed a "gold" shade, was spun by 3-cylinder spinning into a yarn (count 28/2) which was made up into a dense knitted fabric.

Visual assessment after fixing in the usual way (steaming), during which shrinkage of the carbon-black-containing fibre was initiated, revealed a completely uniform colour turnout.

In other words, the optical impression was not impaired by the black component fibres.

Antistatic behaviour: a surface resistance of 6x 10lo ohms was measured after ten domestic washes.

Comparison Example For comparison, a knitted fabric was produced under exactly the same conditions from a polyacrylonitrile fibre to which the fibre according to the invention had not been added.

Antistatic behaviour: surface resistance (after

10 domestic washes) > 1013 ohms.

EXAMPLE 6 A tufted carpet produced in accordance with Example 1 was not piece-dyed, but instead was screen-printed in the usual way (four colour printing: green/olive/brown/ white). The shrinkage of the carbon-blackcontaining fibre was initiated by the necessary steaming process.

Visual assessment: uniform optical impression, no black fibres noticeable. Antistatic behaviour: individual charging values < 500 volts.

Comparison Example Individual charging values of > 4800 volts were measured on the tufted carpet produced under otherwise the same conditions from nylon-6 fibre (20 dtex) to which the fibre according to the invention had not been added.

EXAMPLE 7 1% by weight of the crimped tow produced in accordance with Example 1 (individual denier dtex 18) was doubled with 99% by weight of a nylon-6 filament yarn of dtex 2670 f 126. The mixture of both filament yams produced in this way was wound into package form and subsequently processed under the normal con editions for BCF yarns (bulked continuous filament) into a loop pile carpet with a pile weight of 500 g and a pile depth of 5 mm.

After winch vat dyeing in a light beige colour, during which the carbon-black-containing acrylic fibre was fully shrunk, the carpet was stabilised (as described in Example l) and coated.

Visual evaluation: uniform appearance, no black filaments noticeable. Antistatic haviour: individual charging values < 700 volts.

Comparison Example Personal charging values of the comparison carpet produced without the fibre according to the invention, but under otherwise exactly the same conditions: > 5300 volts.

WHAT WE CLAIM IS:- 1. A fibre or filament mixture comprising from 0.1 to 20iso by weight of synthetic fibres or filaments containing carbon black and having a boiling-induced shrinkage of from 10 to 70%, and from 99.9 to 80% by weight of synthetic fibres or filaments of polyamide, polyester, polyalkylene or poly(mod)acrylic.
2. A fibre or filament mixture as claimed in Claim 1, wherein the carbon black content of the synthetic fibres or filaments containing carbon black is from 5 to 25% by weight, based on the sum total of solids.
3. A fibre or filaments mixture as claimed in Claims 1 or 2, wherein, in their fully shrunk state, the synthetic fibres or filaments containing carbon black have a surface resistance of from 103 to 10" ohms, as measured after 10 washes and at 230C/50% relative humidity in accordance with DIN 54 345, sheet 1.
4. A fibre or filament mixture as claimed in any one of Claims 1 to 3, wherein the synthetic fibres or filaments containing carbon black are (mod)acrylic fibres or filaments.
5. A fibre or filament mixture as claimed in any one of Claims 1 to 4, wherein the fibres or filaments not containing carbon black are fibres or filaments of poly - - caprolactam.
6. A fibre or filament mixture as claimed in

any one of Claims 1 to 4, wherein the fibres or filaments not containing carbon black are fibres or filaments of polycyclohexane - 1,4 - dimethylol terephthalate.
7. A fibre or filament mixture as claimed in any one of Claims 1 to 4, wherein the fibres or filaments not containing carbon black are fibres or filaments of an acrylonitrile copoly- mer.
8. A fibre or filament mixture as claimed in Claim 1, substantially as hereinbefore described with reference to any of the Examples.
9. A process for the production of a fibre or filament mixture, wherein from 0.1 to 20% by weight of synthetic fibres or filaments containing carbon black and having a boilinginduced shrinkage of from 10% to 70% are mixed with from 99.9 to 80% by weight of synthetic fibres or filaments of polyamide, polyester, polyalkylene or poly(mod)acrylic.
10. A process as claimed in Claim 9, wherein the carbon-black content of the fibres or filaments containing carbon-black is from 5 to 25% by weight, based on the sum total of solids.
11. A process as claimed in Claim 9 or 10, wherein, in their fully shrunk state, the synthetic fibres or filaments containing carbon black have a surface resistance of from 103 to 1011 ohms, as measured after 10 washes, and at 230C/50% relative humidity in accordance with DIN 54345, sheet 1.
12. A process as claimed in any one of Claims 9 to 11, wherein the synthetic fibres or filaments containing carbon black are (mod)acrylic fibres or filaments.
13. A process as claimed in any one of Claims 9 to 12, wherein the fibres or filaments not containing carbon black are fibres or filaments of poly - caprolactam.
14. A process as claimed in any one of Claims 9 to 12, wherein the fibres or filaments not containing carbon black are fibres or filaments of polycyclohexane - 1,4 - dimethylol terephthalate.
15. A process as claimed in any one of Claims 9 to 12, wherein the fibres or filaments not containing carbon black are fibres or filaments of an acrylonitrile copolymer.
16. A process as claimed in Claim 9, sub stantially as hereinbefore described with reference to any of the Examples.
17. A fibre or filament mixture when produced by a process as claimed in any one of Claims 9 to 16.
18. Textile structures with permanently antistatic properties comprising a fibre or filament mixture as claimed in any one of Claims 1 to 8 and 17.