DE2337103A1 - ANTISTATIC SYNTHETIC THREAD - Google Patents

Description

DR.-ING. WALTER ABITZ _{Μύηώβη>}

DR. DIETER F. M O R F 2337103 DR. HANS-A. BROWN

Postal address 8 München 86, PO Box 860109

Patent attorneys Pienzenauerstraße 28

Telephone 483225 and 486415 Telegrams: Chemindus Munich Telex: (0) 523992

July 20, 1973 RD-1764/1764-R

EGG. DU PONT DE NEMOURS AND COMPANY 10th and Market Streets, Wilmington, Delaware 19 898, V.St.A.

Antistatic synthetic thread

The use of electrically conductive wire, thinly insulated with electrically non-conductive synthetic fibers, for Manufacture of carpets of low electrostatic charge is described in U.S. Patent 3,639,807. In such carpets, however, the wire can bend and become matted and consequently lose its effectiveness. The use of electrically conductive carbon black distributed in fibers for antistatic textile applications is disclosed in US Pat U.S. Patents 2,845,962 and 3,706,195; however, these fibers have poor mechanical and physical properties Properties, e.g. brittleness and low toughness, and can therefore, under certain circumstances, make processing too normal Articles of daily use and their use in such do not survive, as stated in US Pat. No. 3,582,448 it is pointed out in the soot-containing, electrically conductive

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Coatings on synthetic threads for antistatic two-way use are.

U.S. Patents 3,475,898 and 3,558,419 describe synthetic antistatic threads composed of a sheath and core, with either polyethylene oxide in the core is dispersed or the core of a special polyether-polyamide block copolymer consists. In some applications, however, it has been found that both embodiments lead to an insufficient reduction in the electrostatic charging capacity of the threads and fabrics concerned.

The invention relates to a new synthetic thread with antistatic properties, which consists of an endless, non-conductive sheath made of a synthetic, thermoplastic, fiber-forming polymer, which has an electrically conductive core made of a thermoplastic, synthetic polymer with electrically conductive carbon black dispersed therein surrounds, wherein the jacket occupies at least 50 fi of the thread cross-sectional area (ie at least 50 "fi of the thread volume) and the thread core has an electrical resistance of less than 0.4 x 10 ohms / cm under a direct current potential of 2 kV. For use in low Concentrations mixed with other threads, the core of the threads according to the invention preferably has a resistance of less than 0.4 10 ohm / cm below a direct current potential of 2 kV molecularly oriented in the course of manufacture.

Materials of high electrical conductivity for the core, i.e. those that contain more than 20 percent by weight of soot, are preferably used for threads} in which the proportion of the sheath is at least 80 #.

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The invention provides antistatic threads that can be used in light colored fabrics. For such uses, the sheath proportion of the thread is at least 90 f>, and the sheath is frosted to partially obscure the black core so that the thread has a light reflectivity (as described below, "determined") of more than 20 i> The preferred matted thread contains 2 to 7 weight percent titanium dioxide pigment in the sheath.

By suitable choice of the polymer for the jacket, antistatic threads according to the invention are obtained which are calibrated Color your wish and let it be puffy together under a wide variety of conditions and suitable for uses where the toughness of the jacket is important.

Surprisingly, the threads according to the invention, although they consist predominantly of the non-conductive sheath, which acts as an electrical insulator, can be used as a quantitatively very small component of fabrics, yarns or other textile materials, which mainly consist of other synthetic fibers or threads and one Antistatic protection must be used regardless of the relative humidity for antistatic purposes, e.g. to prevent the accumulation of electrostatic charges. The invention therefore also relates to antistatic yarns and staple fibers consisting of a mixture of non-conductive synthetic threads with threads according to the invention, the latter being present in a proportion of less than 20 percent by weight of the mixture. Concentrations of threads according to the invention in such Mixtures can have an excellent antistatic effect, even if the threads according to the invention are only contained in the mixtures in low concentrations of less than 2 μl ; preferably they contain

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But mixtures of at least about 0.05 percent by weight of these Threads. In such mixtures, the polymer of the thread jacket can be dyed together with the non-conductive threads; in particular, the polymer of the thread jacket can belong to the same polymer class as that from which the non-conductive threads exist.

The particularly preferred products according to the invention are electrically conductive fibers for the manufacture of carpets with an electrostatic charging capacity of less than 2.5 kV, determined according to the test for the electrostatic charging capacity of carpets explained below. These fibers show an excellent combination of electrical conductivity and antistatic properties without an undesirable one To have color.

The invention further comprises a method for producing the antistatic synthetic threads described at the outset, which consists in making an electrically conductive thread core from an electrically conductive soot in dispersion containing thermoplastic synthetic polymer and a surrounding non-conductive sheath made of a synthetic, thermoplastic, fiber-forming polymer spun together in such proportions that the proportion of Sheath is at least 50 # of the thread volume, whereupon the spun threads are collected.

To further explain the invention, reference is made to the drawings.

Fig. 1 is a schematic cross section through a jacket and core existing thread according to the invention.

Figure 2 is a schematic cross-section through an antistatic Yarn which consists of a mixture of threads according to FIG. 1 and non-conductive, synthetic threads.

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With the »in Pig. 1 shown pad cross-section 5 consists of Core 1 made of electrically conductive Huss 3, which is converted into a polymer 4 is embedded, and is surrounded by the jacket 2 consisting of a non-conductive polymer.

According to Pig. 2 are threads with that shown in FIG Cross-section 5 among a much larger number of non-conductive, synthetic threads 6.

The "non-conductive sheath" of the threads according to the invention consists of a synthetic, thread-forming polymer. The threads have an electrical surface resistance of

12th
more than 0.4 x 10 Ohm / cm, determined by contact with the thread surfaces at low DC voltages, for example 100 V or less. Homofibers made from such sheath materials also have resistances of more than 0.4 χ 10 ohm / cm, determined by the same method. Linear polymers of high molecular weight which can be processed into threads of sufficient strength and toughness for the purpose of use are referred to as "thread-forming".

Compared to the non-conductive sheath of high electrical resistance, the core of the filaments has a low resistance and high electrical conductivity once electrical contact has been made with it is. The electrical contact with the thread core can either be made with the help of electrodes that penetrate the sheath and directly come into contact with the core, or be made with the aid of surface contact electrodes, in which case so high an electrical voltage is applied that the current breaks through the thread jacket and thus an electrical one Contact with the core comes about. When using the latter method with surface contact electrodes, If the DC voltage increases to several hundred and especially several thousand volts, a sudden rise occurs

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increased in the amperage, as explained below of the test procedure is described. Once the electrical conductivity has been established in this way has been, the electric current continues to flow, even if the voltage is subsequently reduced, as long as the contact of the thread with the electrodes of the measuring device is not changed.

The low electrical resistance of the core of these filaments is an indication that the core is measured all over The length of the thread is electrically related. Make breaks in the context of the core between the measuring electrodes noticeable by a higher electrical resistance, which approximates that of the mantle. Occasional interruptions in the context of the core are not special for the antistatic behavior of the threads according to the invention harmful. Preferably, however, the core should be the same over the entire length of the fibers or threads according to the invention whether it is staple fibers or filaments, be uninterrupted. It is essential that the core of the thread is over such a length of the thread is uninterrupted that the thread in question together with other such antistatic Forms an effective antistatic network. Threads that have been tested in accordance with the test procedures described here have the specified level of electrical conductivity of the core, provide effective antistatic protection.

The thread jacket can be made of any extrudable, synthetic, thermoplastic, thread-forming polymers or copolymers exist. These include polyolefins, such as polyethylene and polypropylene, acrylic polymers, polyamides and polyesters of thread-forming molecular weight. Particularly Suitable polymers for the thread jacket are those produced by condensation of diamines and dicarboxylic acids or of Polyamides, especially polyesters, are obtained from amino acids

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those from terephthalic acid or isophthalic acid and lower glycols, such as ethylene glycol, tetramethylene glycol and hexahydro-p-xylylene diol, as well as the polyacrylonitriles. These polymers can be colored in a known manner be modified, e.g. by introducing basic or acidic dye sites by copolymerization, in order to mix them and to facilitate their co-dyeing with other dyed or dyeable synthetic fibers.

The tensile strength properties and the other physical properties of the threads according to the invention depend on primarily from the polymer of the jacket. For threads of high strength is used as the material of the sheath Polymers of higher molecular weight and those that can be stretched to a higher degree »Although undrawn Threads according to the invention can have sufficient strength for some applications, are drawn Threads preferred.

The thickness of the jacket must be sufficient to give the core the required To provide protection, e.g. strength, as well as heat and abrasion resistance, and to hide the core when this is necessary. In general, the jacket should have a thickness of at least 3 μ; the use of larger jacket thicknesses depends on the titer or diameter of the thread that can be used. For normal textile thread count suitable jacket thicknesses are in the range from 8 to 22 μ. Under certain circumstances, if the threads are processed e.g. at high temperatures need to be, e.g. by bulging in the hot gas or steam nozzle or by texturing, it is essential that the thread jacket has such a high melting point that it does not soften or melt under the processing conditions. For such applications are preferably used for the Coat a higher melting polymer, such as polyhexamethylene adipamide, instead of polycaprolactanu

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The thread core consists of a dispersion of electrically conductive carbon black in a thermoplastic polymer. The core material is selected primarily taking into account electrical conductivity and workability. The soot concentration in the pad core can be 15 to 50 $> . With soot concentrations of 20 to 35 #, which are preferred, a high electrical conductivity is obtained, while the processability is still maintained to a sufficient extent. The material for the core preferably has a specific resistance of less than 200 ohm / cm and in particular of less than 50 ohm / cm. The use of known, electrically more conductive types of soot produced especially for this purpose enables the required amount of soot to be reduced to a minimum.

Since plastic masses are stiffened by high soot loads, the generally softer, lower-melting ones become Polymers (which also have a correspondingly lower glass transition temperature have) preferred materials for the pad core over the stiffer, higher-melting polymers. The polymer of the core preferably has a lower melting point and a lower glass transition temperature than that of the thread jacket; this makes processing easier (e.g. prevents breakage of the thread core and interruption in the distribution of soot particles), while the electrical Conductivity in the pad core and the finished thread is retained. It is not essential that the material is of the thread core can be spun into threads by itself, and therefore needs the polymer for the thread core not to be a thread-forming polymer. The thread core polymer should, however, be among those used for spinning the polymer required conditions heat-resistant and extrudable be. Suitable polymers for the mass of the thread core in which the carbon black particles are embedded e.g. polyamides, polyesters, acrylic polymers, polyethers, polycaprolactone and polyolefins (e.g. polypropylene, high and low

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printing polyethylene). These polymers can be used to facilitate processing with other substances, such as oils or Grow, be mixed. Copolymers, such as those made from ethylene and vinyl acetate, can also be used.

The carbon black can be incorporated into the fiber core polymer by known mixing processes be distributed. Care must be taken to ensure that the carbon black is distributed so evenly in the fiber core polymer to achieve that the mass without excessive mixing and the associated decrease in electrical conductivity Extrusion lets.

For satisfactory spinning it is important to remove volatile substances from the polymers to which the carbon black has been added is to be removed prior to melt spinning. This can take place during or after the cooperation of the carbon black with the polymer. It can also be useful to dry such polymers under a low vacuum at 68 C for 16 hours, for example. Furthermore, the usual precautionary measures are used to prevent oxidative decomposition during spinning "by one e.g. excludes the oxygen in the polymer lines with the help of inert gas, etc.

The cross-sectional area (which is directly related to the filament volume stands) the electrically conductive core of the composite thread only needs to be sufficient to the thread to give the desired electrical resistance and may only need to be 0.5 percent by volume. The lower one The limit depends primarily on the processability into sheath-core threads of a sufficiently uniform * consistency if the cohesion of the thread core is still sufficient with the low thread core volumes.

The spinning of the threads according to the invention can be carried out in conventional Spinning systems for spinning sheath-core threads from two polymers are made, the different ones

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Properties of the two components must be taken into account are. The threads can easily be produced by conventional spinning processes with polymers, such as those in the U.S. Patent 2,936,482. Further instructions for spinning polyamides can be found in the U.S. Patent 2,989,798.

The threads can be drawn by conventional methods; however, care must be taken to avoid sharp corners that could break or damage the core of the thread. In general, the hot stretching process is preferably used, in which the thread is additionally heated during drawing. This creates the core material is further softened and stretching is made easier. The antistatic threads can be used with conventional, synthetic, undrawn Threads are pinned and stretched together.

The threads according to the invention can easily be with a Toughness of at least 1.5 g / den, which is perfect is sufficient if the threads are mixed with other threads as a component that is smaller in terms of quantity. Preferably the threads have an elongation at break of at least 10 9 ^, but less than 150 ^, on. The properties of the mixed textiles depend primarily on the properties of the other threads. For general purposes, the threads according to the Invention a thread denier of less than 50 and preferably less than 25 den.

The threads can have a round or non-round cross-section, an eccentric or concentric arrangement of dumbbell and core as well as combinations of these features. Because of the concentric Arrangement achieves the best protection and the best concealment of the thread core. The fineness of the core of the thread greatly hides it, and fine-core threads can be found in dyed or patterned fabrics

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▼ are used that otherwise do not cover the core of the thread Feature. In addition, the core of the thread can, if the «is necessary, with the help of an opacifier in the form of cavities or in the form of a white, solid, powdery matting agent, such as titanium dioxide, in the Cover the coat. Out of round, see B. multi-leaf cross-sectional shapes further help to hide the core of the thread.

Variables that affect the hiding of the core of the thread include the thickness and dyeability of the coat, the Ratio of cladding to core, the concentration of matting agents, such as titanium dioxide, in the cladding and cavities, which come about through separation between the sheath and core and can occur when the threads are oriented whose sheath and core consist of dissimilar polymers, in which e.g. the sheath is made of a polyamide and the core is made of polyethylene.

Without a covering thread jacket to hide the black color, fibers filled with carbon black generally have a light reflectance of less than 5 $ it is avoided that light-colored textile fabrics take on a darker color due to the threads according to the invention.

The threads according to the invention are capable of all types of Textiles such as knitted fabrics, carpets, woven fabrics and nonwovens provide excellent anti-static protection to lend. You can use conventional additives and stabilizers such as colorants and antioxidants. contain. she can be subjected to all kinds of textile processing methods such as crimping, texturing, washing, bleaching, etc. They can be combined with staple fiber yarns or filament yarns

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and used as staple fibers or filaments.

The threads according to the invention can be used in the course of the yarn production (e.g. when spinning, drawing, texturing, plying, rewinding, yarn spinning) or in the production of the Textiles are combined with other threads or fibers. Care should be taken to ensure that the antistatic threads suffer as few breaks as possible. For example, the Handling the relative lengths and shrinkages of the antistatic threads and the other threads coordinated with one another to ensure good processability and the desired luffability, skilability, rotatability or texturability to achieve.

Description of the test methods Electrical resistance of the thread core

The electrical resistance of the thread core is determined from the current intensity measured when a voltage of 2 kV is applied to a 5.08 cm long sample. A suitable device is the 15 kV "Biddle Dielectric Tester" (James G. Biddle Company, Plymouth Meeting, Pennsylvania, USA). A three-thread bundle is just clamped between two electrodes two inches apart, and sufficient voltage is applied to observe a current flow (e.g. 1-4 kV). As soon as current flows, the voltage is set to 2 kV and the current strength is calculated according to Ohm's law R = E / I. If the current strength at 2 kV in a 5.0 cm long sample is, for example, 10 μΑ, the resistance for the three threads is 0.4 x 10 ⁸ Ohm / cm. The cons

stand per thread is then 1.2 χ 10 Ohm / cm. To at that Above attempt to achieve current flow, the voltage should be increased gradually to avoid a sudden increase in the Avoid the strength of the current which could burn out the threads. Burning out can easily be done visually (on

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broken, melted or charred threads), and such samples must be disregarded in the determination stay. The resistance of threads shorter than 5 cm can be adjusted by adjusting the distance between measured by the electrodes.

Reflectivity

The light reflectivity, namely the brightness or whiteness of the sample compared to a standard made of magnesium oxide, is determined with a photoelectric reflectometer. A suitable device is the Photoelectric Reflectometer, Model 610, with a green color mixing filter (Catalog No. 6130), "Search Unit Model 610-Y" and a white-lacquered working standard plate that is calibrated to have a reflectivity of $ 70 to $ 75 (Catalog No. 6162) available from Photovolt Corporation, 95 Madison Avenue, New York, NY 10016. The electrically conductive thread sample on which the measurement is to be made is measured to be two inches by three inches black mirror cards (in about six layers of thread) wound up and the reflectivity on the cards (as an average of 10 measurements) determined.

Percentage of soot in the core

To determine the soot concentration in the material of the thread core usual analytical methods can be used. A process suitable for polyethylene containing carbon is described or can be derived from ASTM test standard D1603-68 will. This is the thermogravimetric method, which is suitable for use in the absence of non-volatile Pigments or fillers except carbon black are suitable.

Percentage of the core in the thread

The easiest way to determine the volume percentage of the core is by taking the cross-sectional area of the black core

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by measurement under the microscope with that of the whole thread compares. This can easily be done at about 400x magnification. With round threads you can choose the size easily calculated from the ratio of the square of the core diameter to the square of the total thread diameter. Take the mean of ten determinations to remove any irregularities balance. In the case of threads with a non-circular cross-section, the calculation can easily be carried out using measurements, which have been carried out on photomicrographs of thread cross-sections at a known magnification are.

If the polymer of the jacket differs from that of the core differs by such a different solubility that it can be removed by the action of solvents one gravimetrically determine the percentage of the core by dissolving the shell and adding the weight of the insoluble Compares the core to the weight of the original sample. So can be used, for example, to dissolve a shell made of polyhexamethylene adipamide Use formic acid from a polyethylene core.

Determination of the specific resistance of the core material

The specific resistance of the core material containing carbon black is determined by measuring the direct current resistance over a length of a 2.54 cm wide and 0.25 mm thick strip of foil measures 5.08 cm. Such films can be easily pressed by pressing a powdery or tablet-shaped sample of the core material between two aluminum foils in one over the Melting point of the core material heated press under a pressure of 1400 kg / cm in the course of 1 to 2 minutes. After cooling, the aluminum foil is peeled off the sample foil, and the sample becomes 2.54 cm wide and Cut out strips about 6.35 to 7.62 cm long. The fat

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the foil is measured with the micrometer. A strip is placed between two 5 _f 08 cm distant from each other copper electrodes clamped, and the GleichBtromwiderstand is determined with an ohmmeter. The specific resistance of the film in ohms »cm is calculated from the reading of the measuring device in ohms as the product of the measured resistance, multiplied by the width, multiplied by the thickness, divided by the length of the sample, all expressed in om.

example 1

Concentric sheath-core threads with a sheath made of polyhexamethylene adipamide with a relative viscosity of 45 and a polyethylene core containing 20 # electrically conductive carbon black are produced. The carbon black is an "extra-conductive" oil furnace black ("Vulcan XC-72") (non-volatile carbon 98 #, volatile substances 2 #, particle size 30 αμ, lowest specific electrical resistance in the dry state), available from Oabot Corporation, 125 High Street, Boston, Massachusetts-02110, USA. This Ruse is described in the technical reports "S-8" and "1518/173" of the company mentioned. The carbon black dispersion is prepared by grinding the carbon black at 120 ° C. with high pressure polyethylene (density 0.916; melt index 23; "Alathon 2821" from the applicant) in a dough mixer. The carbon black is added slowly and the mixture is poured 10 minutes after the addition of carbon black has ended. This polyethylene is chosen for its softness. (Other suitable resins are high-pressure polyethylene having a density of 0.916 and a melt index of 11.9 ( "Alathon 20" of the applicant) alone or in admixture with 15 to 40 i "oil or wax.) The molten carbon black mixture through a sieve filtered with a mesh size of 0.15 mm and extruded. Press foils show an excellent distribution of soot and electrical conductivity with a specific resistance of 12.7 ohm.cm. Under

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Turning this material for the core, sheath-core continuous filaments, namely three monofilaments with a denier of 65 denier, are spun at a speed of 389 m / min, the total denier being kept constant and the volume of the core being reduced by changing the pumping speeds that the samples shown in Table I are obtained. The core volume is determined by the pumping speed and confirmed by analyzing the cross section of the threads at 200 times magnification. A three-hole spinneret made of stainless steel is used, to which the polymers for the jacket and core are fed concentrically and individually until they emerge at the front face of the spinneret. An insert capillary is used to guide the core polymer to the front surface of the spinneret, where it emerges surrounded by the jacket polymer. The threads are harvested with a thread denier of 65 denier. Then they are stretched 3.06 times at a speed of 183 m / min on a curved heating plate maintained at 150 ° C. The physical and electrical properties of the yarns are shown in Table I,

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T a b e 1 1 50 e I 40 3 25th 4th 18th 5 12th Ch
-P * Sample no. 1 21.4 2 20.6 21.4 21.2 19.9 -J
Ch Core volume, $> 1.5 1.9 2.4 2.8 3.4 I. Thread titer, den 26.2 36.4 30.3 54.7 57.4 Tenacity, g / den 15.3 17.9 25.1 20.3 25.2 Elongation at break, # 0.98 2.64 1.57 5.24 Initial modulus, g / den - 1.6 3.4 3.4 4.6 Electrical resistance χ 10,
Ohm / cm / thread * 2.0 3.0 2.8 3.0 2.6 Breakdown voltage, kV Electrostatic charger
like the carpet. kV
(according to example 2)

* Calculated from the current in μΑ, determined at 2 kV.

The sample carpets in Table I are made from a commercially available 204-thread pile carpet yarn made from polyhexamethylene adipamide with a total denier of 3700, consisting of three-winged continuous threads, with a pile height of 1.27 cn. A strand of the electrically conductive thread (about 0.56 percent by weight) is unwound with the carpet yarn folded and then used for pimpling. The visibility of the electrically conductive threads in the carpet decreases noticeably with decreasing thread core volume

Example 2 Production of the thread jacket polymer

A stainless steel vessel is charged with 317.5 kg of an aqueous solution containing 50% by weight of hexamethylene diammonium adipate, whereupon 721 g of a 10% by weight solution of manganese (II) hypophosphite / Rn (E2 ^ 2 ^ 2 · - ^ in Water, 70 g of 25 percent by weight acetic acid and 100 ml of an 11.2 percent silicone antifoam agent are added. The mixture is concentrated by evaporation * to a solids content of 75 percent by weight and transferred to a stainless steel autoclave equipped with a stirrer displaced from the autoclave by inert gas and the contents heated to 200 ° C. up to a pressure of 17 atm. Then, 14.83 kg of a 49 percent strength by weight aqueous titanium dioxide slurry are added with stirring The polymerization is continued according to Example 1 of US Pat. No. 2 163 636. After the end of the polymer In the ion reaction, the molten polymer is extruded in the form of 6.3 mm strands. After cooling with water, the strands are cut into 6.3 x 4.7 mm chips, which are suitable for remelting in a spinning device. The flakes have the following properties:

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Relative viscosity 43.5

(NH ₂ ) 46.0 A TiO ₂ 5.04 Mn (H ₂ PO ₂ J ₂ 0.048 Thread core polymer composition Polyethylene

⁶ g

70 percent by weight

Electrically conductive carbon black

Example 1 30 percent by weight

Polyethylene; "Alathon PE-4318" high pressure polyethylene (density 0.916j melt index 23 according to ASTM-D-1238), manufactured by EI du Pont de Nemours and Company, for injection molding. The polyethylene contains 50 ppm of OxidationsYerjsogei'er, for its heat and aging resistance to improve,

Manufacturing

A 3.7 l double-bladed Teignfischer is charged with 1905 g of polyethylene and 816.5 g of carbon black. Daa geese is mixed for 30 minutes at 140 ° C, extruded, sieved through a 0.15 mm mesh size sluice and shaped into tablets.

The product has the following characteristics:

Specific resistance
(a film cast at 180 ° C.) 2.9 to 4.2 ohm · cm

Soot content $ 30.2

Moisture content 0.04 #

If the moisture content is higher than 0 * 1 #, the Tablets before spinning 2Λ hours at 70 ° G in a vacuum to be dried.

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RD-1764/1764 - R Spinning

The polymers for the shell and the core are in one Tendon melt spinning machine using the in the U.S. Patent 2,936,482 spinneret arrangement shown spun into concentric sheath-core filaments.

The jacket polymer is processed at a throughput rate of 19.8 g / min (calculated from the capacity and speed the pump) and the core polymer with a throughput rate of 0.7 g / min (calculated from the capacity and speed of the pump), so that a concentrically arranged composite thread is obtained, which is 96 percent by volume consists of jacket and 4 percent by volume of core. When spinning, the temperatures of the polymers for the Shell and core in the screw melter as follows set:

Temperature of the temperature of the

Zones of the screw jacket polymer, core polymer, melting device ⁰ Q Oq

above 149 120 center 285 222 below 288 265

The spin block temperature is 293 ° C. The filling funnel for the two polymers are flushed through with inert gas.

The relative viscosity of the jacket polymer when it emerges from the spinneret (during free fall) is 56; the rise the relative viscosity is the consequence of a further polymerization of the dried polyhexamethylene adipamide in the screw melter. The spinning speed is 814 m / min. The collected spun yarn is gray and has the following characteristics:

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Finishing on the yarn y-s- / 1.0 # Kern, Vol.96 4

Mantel, VoI S 96

! Pus of the spun bundle,

the 60th

Number of threads per bundle 3 reflectivity 37-40 #

The stretching

The electrically conductive three-ply yarn of 60 denier is wound in a draw twisting machine at a winding speed stretched at a speed of 366 m / min and a shoe temperature of 180 ° C. to 2.7 times.

The drawn yarn has the following properties:

Thread count 3

Strength, g / den 3.8

Elongation at break, # 35

Modulus, g / den at 10 percent elongation 13

Electrical resistance ₇

of the core bundle 1.8 10 Ohm / cm

Reflectivity 34 #

Common puffing

A strand of a 160-ply 4-cavity hollow filament polyamide yarn of 3400 den, as described in British patent specification 1,292,388, is puffed together with a strand of the electrically conductive yarn at one point on the hollow filament spinning machine. The yarns are combined in a heating box under a tension of 10 to 20 g on the last wrap around the heat setting roller before they reach the bulking nozzle. The heat setting roller is at 195 ° C and the yarn speed is 1084 m / min. That

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Common puffing is done by passing the yarn through an under A bulk nozzle operated at a pressure of 8.44 kg / cm at 240 ° C of the type described in Belgian patent 573 230 is directed, whereby threads with a random, three-dimensional, curvilinear curl with alternating S and Z twist. The yarn is then cooled and wound up.

The tensile properties of the bulked yarn are approximately the same as those of the parent yarn. Sham-dyed carpets with flat knobs (pile height 1.27 cm, weight per unit area 0.996 kg / m, fabric density 4 mm, 7 stitches per 2.5 cm), made from yarns that contain the electrically conductive threads (sample) and from yarns that contain contain no electrically conductive threads (control), with a commercially available polypropylene nonwoven as a carpet base ("Typar" from DuPont), and which are rubberized with conventional latex, provide the following values for the electrostatic charging capacity at 20 % relative humidity and 21 ° C :

Electrostatic charging capacity of the carpet

Sample 1.5 to 2.0 kV

Control 10.2 to 11 kV

This test conforms to AATCG test standard 134-1969 with changes made by the Carpet and Rug Institute in September 1971.

In the raw carpets and the shine-dyed carpets, the three-ply 20 denier strands are made up of electrically conductive threads a very faint bluish tinge. Dyed carpets made from bulk yarns containing electrically conductive threads, show no difference in most monochrome tones and only slight differences in certain monochrome tones light colors, e.g. yellow, orange and pink, when compared to the control carpet.

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J 3

Optionally, the threads according to the invention can be in the form of staple fibers, e.g. in amounts of 0.5 to 5 percent by weight, together with non-conductive staple fibers in carpet yarn be used.

Example 3

This example shows that one must be careful to that the threads according to the invention do not lose conductivity when they are drawn.

There are threads with an eccentric sheath-core arrangement with a sheath made of polyhexamethylene adipamide, which has a relative viscosity of 44 and 0.3 ^ TiO ₂ , and a core made of polycaprolactam (relative viscosity 45; 31 »8 equivalents of NH _{2 end} groups each 10 g) with a carbon black content of $ 20> spun. The carbon black is the same as in Example 1. The proportion of the core in the threads is 40 percent by volume. The three-ply yarn is spun with a linear density of 79 den. The yarn is cold drawn on a drawing pin. As Table II shows, the electrical resistance of the cold drawn yarn increases with the draw ratio. When the yarn without pin on a curved hot plate at 160 ° C ⁿ hot stretched "is found virtually no increase in resistance instead. It is likely that is so far softened on heating of the yarn in a heated stretching zone upon stretching of the core that a rupture of the core or an interruption in the distribution of carbon particles, which is necessary for conductivity, is avoided.

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Table II

Electrical resistance Draw ratio of the core, ohm / cm / 3 threads

1 (undrawn) 0.6 χ 10 ⁸

1.5 2.4 x 1NC ¹²

3.0 2.0 χ 10 ^U

3.0 (hot drawn). 2.75 χ 10 ⁹ *

* Calculated from individual determinations on the three threads.

Example 4 Sheath polymer ris at

Polyethylene terephthalate flakes with a relative viscosity of 23-2, determined on 0.8 g of polymer in 20 ml of hexafluoroisopropanol at 25 ° C.

Core polymer

Polycaprolactam with 22 fo electrically conductive carbon black according to Example 1.

Manufacturing

A predispersed slurry of 22.680 kg of electrically conductive carbon black ("Cabot XC-72"), 86.180 kg of caprolactam and 83.910 kg of distilled water is prepared in a mixing vessel with stirring at 50 to 55.degree. This slurry is charged to a stainless steel autoclave with a capacity of 227 kg and provided with a stirrer. The autoclave is cleared of air and filled with inert gas, whereupon heating begins. The temperature of the autoclave is increased to 258 ° C. and the pressure to 17.6 kg / cm ² in order to carry out the initial ring opening of the caprolactam and the prepolymerization reactions. After this heating period, which lasts about 6 to 7 hours, the pressure will gradually decrease within 1 1/2

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is

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Relaxed hours from 17.6 kg / cm to atmospheric pressure (relaxation period). The polymer is then extruded at 278 C as a continuous band, cooled with water and cut into 3.2 mm flakes. The flakes are washed with water for 4 hours with stirring in a kettle at 95 ° C. in order to remove residues of the monomer. This operation is repeated three more times; Finally, $ 6.3 caprolactam was extracted. The polymer is in vacuo; (635 mm Hg) dried until the moisture content is less than $ 0.3. The flakes are remelted, extruded, sieved through a sieve with decreasing mesh sizes (0.6-0.074 mm) and compressed into tablets, which are then dried in vacuo to a moisture content of less than 0.03 $>.

The specific electrical resistance of films cast from this polymer varies between 10 and 60 ohm »cm.

Spinning and drawing

The polymers for the shell and the core are in a combined spinning and stretching machine at a winding speed of 1372 m / min (calculated from the speed of the take-up roller in rpm) spun together and stretched.

The jacket polymer is produced at a throughput rate of 29.7 g / min (calculated from the linear density in the spun state and the winding speed) and the core polymer with a throughput rate of 6.7 g / min (calculated from the denier in the spun state and the winding speed), so that a concentric sheath-core thread 81 percent by weight (calculated from the throughput rates) from the jacket and 19 percent by weight (calculated from the throughput speeds)

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Core consists. When spinning, the temperatures in the Screw melting device set as follows:

Temperature of Temperature of Tendon Sheath polymer, Core polymer, melting zone ⁰ C ⁰ C above 249 206 center 281 250 below 289 265

The spinning block temperature is 290 ° C. The yarn is under Use of a steam-operated stretching nozzle and electrically heated rollers kept at 180 ° G (16 wraps) stretched three times.

The drawn yarn is black and has the following properties:

Number of threads per bundle Yarn, $> 1 Titer den of the core 19.02 Overall finish on the ... 1.83 Electrical resistance 1.3 x 10 ^y Strength, g / den 2.5 Elongation at break, $ 39.9

Module at 10 percent

Elongation, g / den '13.6

Example 5 Sheath polymer

Polyethylene terephthalate flakes with a relative viscosity

from 30.. ■ "■ -

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Kernpolyiiieri sat

Manufactured according to example 2.

Spin

The shell polymer and the core polymer are made together according to Example 2 at a speed of 787 m / min spun. The shell polymer is nit a throughput rate of 36.3 g / min (calculated from the speed and capacity of the pump) and the core polymer fed at a throughput rate of 1.38 g / min (calculated from the speed and capacity of the pump), so that a concentric composite thread is obtained, 96 percent by volume of sheath and 4 percent by volume Core exists, determined by enlarged cross-sectional images.

When spinning, the temperature of the screw melting device for the jacket polymer set as follows:

SchnpcVpn— Temperature of Temperature of pre-melt Sheath polymer, Core polymer, direction ⁰ C ⁰ C Zone 1 286 114 (top) Zone 2 284 184 (center) _ 242 (bottom) -

The spinning block temperature is 292 ° C.

A three-thread yarn of 60 denier is spun.

Stretch

The three-ply 60 denier sheath core yarn is made at one speed from 415 m / min on a 97 ° C hot shoe to the Stretched 3.8 times. - '

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The drawn yarn has the following properties:

Titer, the 17.2

* 3 thread count

Electrical resistance 3

of the core, ohm / cm / thread 2.66 χ 1Q

Strength, g / den 5.3

Elongation at break, # 21.5

Initial module at

10 percent elongation, g / den 43.2

This sheath core yarn is used together with a commercially available, 34-ply polyester yarn of 150 denier textured in a "Leesona 57O" false twist texturing machine. That jointly textured yarn (a strand of three-strand sheath core yarn of 17.2 denier with a strand of 34-ply polyester yarn of 150 denier) becomes a "Swiss pique" double knit processed. This knitted fabric is dyed and finished using known methods. After being washed 30 times the knitted fabric examined in an electrostatic tester (Electrometer, Model E525, from Presco Scientific Company) and compared with a control knitted fabric made only from the same polyester yarn under the same conditions is.

Electrostatic charge on the knitted fabric, T after 0 seconds after 120 seconds

Trial fabric 400 380

Control knitted fabric 2750 2550

This results in good electrostatic protection of the test fabric.

B is ν ie 1 6

A three-thread yarn of 60 denier is made from the polyhexamethylene adipamide used in Example 2 as a polymer

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prepared for the cladding and the polycaprolactam used in Example 4 with a soot content of 28 f "as the material for the core. Threads, which consist of 96 percent by volume of sheath and 4 percent by volume of core, are stretched 3.0 times on a curved heating plate (61 cm) heated to 180 ° C. The yarn then has the following properties:

Bundle titre, den 20.2 Q Strength, g / den 3.18 1.77 x 1Q ^y Elongation at break, $> 49.1 32 Initial modulus, g / den 24.4 Electrical resistance of the core, ohms / cm / thread. Reflectivity, # Common puffing

The electrically conductive yarn is made according to Example 2 together with a 68-thread, base-hardenable, endless hollow thread carpet yarn from polyhexamethylene adipamide with a titer from 1225 den (type 854 Antron II from DuPont) and carpets with flat knobs with a pile height

of 6.35 mm and a basis weight of 0.475 kg / m, as described in Example 2.

The reflectivity and the electrostatic charging capacity of shine-colored carpets are measured with the corresponding Compared properties of control carpets that do not contain electrically conductive yarn.

Electrostatic

Charging capacity Reflectivity of the carpet, kV * of the carpet, %

Sample 1.5 to 2.4 65

Control 8.6 to 9.8 75

* as in example 2.

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The visual classification of the carpets corresponds to the measured one Reflectivity.

Example 7

Threads (4 strands with a spun denier of 60 denier, 3 threads) with a polyamide sheath and a polyethylene core according to Example 2, which are produced for use as staple fibers have the following properties:

Finishing on the yarn, ° f> 0.43

Weight # core 3.5

Weight - $ coat 96.5

Carbon content of the core, # 32.3

Reflectivity, fo 39

_7th grade electrical resistance

Core bundle (12 threads) 2.0 10 'ohm / cm

The sponnone ¹ I-arn is stretched by combining 8 strands in a test stretching machine and stretching them 3 × 0 times at a winding speed of 210 m / min "at a hot shoe temperature of 180 G.

The drawn yarn has the following properties:

Bundeltiter, the 690

96 thread count tenacity, g / den 4.72

Elongation at break, i » 18.5

This electrically conductive yarn bundle is cut into approximately 16.5 cm long pieces and mixed with commercially available carpet staple fibers made of polyhexamethylene adipic acid (DuPont T-838) in quantities of 0.6, 2 or 5 * $> during carding. Under normal piling conditions, the blends are made into two stringy spun yarns with a cotton number of 2,4-

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Processed with 3.5 Z twists and 3.5 S twists each 2.54 cm. The yarns are heat set in the autoclave and then made into carpets with cut pile (electric wool style) by a surface weight of 1.19 kg / m, a fabric density of 3.96 mm and a pile height of 1.90 cm with a polypropylene base processed and rubberized with commercially available latex. The carpets are washed and washed in a conventional manner a mixture of three commercially available yellow, red and blue acid dyes.

The dyed carpets give in the shuffle test at 20 ° relative humidity and 21 ° 0 dii
electrostatic charging capacity:

ver humidity and 21 ° 0 the following values for the

Ratio of electrostatic antistatic fibers - chargeability of the

to basic fibers of carpets, kV *

0: 100 9.4

0.6: 99.4 3.2

2.0: 98.0 * 2.5

5.0: 95.0 1.9

* as in example 2.

Example 8

This example illustrates an additional capacity for variation in the application of the invention. Each sample has three threads each Strand, and the soot is the same as in Example 1.

Sample A is similar to the sample produced according to Example 2 with the difference that the threads have a ribbon-shaped cross section to have. The material for the thread core contains an oxidation retarder 0.25 percent by weight 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene.

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Sample B is similar to Sample A; however, the threads have a three-winged one Cross-section with a modification ratio of 2.50.

Samples C to H have round thread cross-sections.

Sample C consists of threads with a sheath made of polyhexamethylene adipamide, which contains 5 # titanium dioxide, and a core which consists of 40 $> from polypropylene, 20 # from polyethylene, 10 # from a commercially available elastomeric copolymer of ethylene, propylene and a non-conjugated diene and at $ 30> made of carbon black.

Sample D consists of threads with a sheath made of commercially available polypropylene ("Shell PWD-152") and a core as in the Sample A.

Sample E has the same casing as the sample D, while the core of a commercial polycaprolactone resin ( "Union Carbide PCL-700") having a carbon black content of 30 f>.

Sample F has a sheath of polyhexamethylene adipamide with a titanium dioxide content of 5 $> and a core of a commercial polypropylene resin ( "Hercules 8MSR") having a fiussgehalt of 25 #.

Sample G has a sheath made from the same polypropylene as Sample D and a core made from a commercially available polyethylene ether resin ("DuPont TLF 1681S") with a carbon black content from 26? p.

Sample H is a non-antistatic control sample with a Polyamide sheath, as in sample A, and a core made of the same polyethylene resin, but without carbon black content.

The properties of the threads in these samples are shown in the table III.

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sales
ratio T a b e S3 III fracture
strain, 2337103 2.77 Titer,
the lie 68.4 sample 2.7 21.6 Firm
ability,
S / den 81.8 At first-
module,
"/the A. 3 21.1 2.65 62.8 21.6 B. 2.26 110.6 3.00 126 22.1 C. 2.0 42.3 2.19 150 14.2 D. 2.5 104.4 3.69 34.2 28.6 E. 2.0 33.3 1.72 108 14.7 P. 2.70 55.7 2.49 34.5 17.6 G 19.1 3.29 28.7 H 3.87 23.6

Table III (continued) Core portion, reflection electrical resistance

Vol .- # by virtue of Q
of the core yarn χ 10 °, sample (Cross-section) Yarn, $ Ohm / cm / thread A. <10 28.5 1.2 B. - ■ 35 0.97 G 3 49 3.54 D. 7.5 11 3.54 E. 7.4 12.5 0.15 F. 7.5 31.6 11.8 G 15th 11 0.12 H 4th > 10 ⁷

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Claims (27)

Claims 1. Antistatic synthetic thread, "consisting of an endless, electrically non-conductive sheath made of a; synthetic thermoplastic thread-forming polymer which surrounds a core made of a synthetic thermoplastic polymer and occupies at least 50 5" of the thread cross-sectional area, characterized in that the core in the thermoplastic synthetic polymer contains dispersed, electrically conductive carbon black, is itself electrically conductive and has an electrical resistance of less than 0.4 x 10 ⁿ ohm / cm under a direct current potential of 2 kV. 2. Thread according to claim 1, characterized in that the jacket occupies at least 80 fo the thread cross-sectional area and the electrically conductive core contains more than 20 percent by weight of carbon black. 3. Thread according to claim V or 2, characterized in that that it has a strength of at least 1.5 g / den. 4. Thread according to claim 1, characterized in that the Sheath occupies at least 90 $ of the thread cross-sectional area. 5. Thread according to claim 1 to 4, characterized in that the jacket is at least 3 μ thick. - 34 - 4098Q7 / 1Ü20 3 * 6. Thread according to claim 1 to 5, characterized in that the jacket is 8 to 22 μ thick. 7. Thread according to claim 1 to 6, characterized in that the jacket is matted and the thread has a light reflectivity of more than 20 i » . 8. Thread according to claim 1 to 7, characterized in that the jacket has 2 to 7 percent by weight of titanium dioxide as a matting agent contains. 9. Thread according to claim 1 to 8, characterized in that the sheath made of polyhexamethylene adipamide and the Core consists of polycaprolactam. 10. Thread according to claim 1 to 8, characterized in that the sheath made of a polyamide and the core of polyethylene consists. 11. Thread according to claim 1 to 8, characterized in that the jacket is made of a polyester. 12. Thread according to claim 1 to 11, characterized in that the core contains 15 to 50 percent by weight of carbon black. 13. Thread according to claim 1 to 12, characterized in that the core contains 20 to 35 percent by weight of carbon black. 14. Thread according to claim 1 to 8, 12 and 13, characterized in that that the polymer of the thread core has a lower melting point and a lower glass transition temperature has than the polymer of the thread jacket. 15. Thread according to claim 1 to 14, characterized in that that the coat is molecularly oriented. - 35 4098 07/1020 Si RD-1764/1764-R '2337133 16. Thread according to claim 1 to 15, characterized in that that the thread core under a direct current potential of 2 kV has an electrical resistance of less than 0.4 x 10 ohm / cm. 17. Continuous thread, characterized in that it consists of a mixture of electrically non-conductive synthetic threads and there is less than 20 percent by weight of threads according to claim. 18. Continuous thread yarn according to claim 17, characterized in that that the threads are puffed together. 19. Continuous thread yarn according to claim 17, characterized in that that the threads are pinned. 20. Continuous thread yarn according to claim 17 to 19, characterized in that that the polymer of the thread jacket can be dyed together with the non-conductive synthetic threads. 21. Continuous thread yarn according to claim 17 to 20, characterized in that that the sheath of the sheath core threads consist of a polymer of the same class as the non-conductive synthetic threads. 22. Staple fiber mixture, characterized in that it consists of electrically non-conductive synthetic threads and less than 20 percent by weight of threads according to claim 1 consists. 23. A method for producing the synthetic antistatic threads according to claim 1, characterized in that one an electrically conductive thread core made of an electrically conductive soot in dispersion containing thermoplastic synthetic polymer and a thread core - 36 - U C 9 8 C 7 / '■ Q Ί 0 RD-1764/1764-R surrounding, electrically non-conductive thread jacket a synthetic thermoplastic thread-forming polymer spun together in such proportions that the proportion of the polymer for the thread jacket is at least 50 percent by volume, whereupon the spun threads are collected. 24. The method according to claim 23, characterized in that a mass with a specific electrical for the core Resistance less than 200 ohms / cm used. 25. The method according to claim 23 or 24, characterized in that the soot is uniformly in the thermoplastic synthetic polymer that a decrease in conductivity due to excessive mixing is avoided. 26. The method according to claim 23 to 25 »characterized in that that the threads are then stretched so much that they assume a strength of at least 1.5 g / den. 27. The method according to claim 26, characterized in that the threads are heated during drawing. - 37 409807 '1 Q 2 0 Lee r side