DE2337103C3 - Antistatic synthetic two-component thread, process for its production and mixed continuous filament yarn or staple fiber mixture - Google Patents

Description

The invention relates to an antistatic synthetic two-component thread of the core-sheath type and a method for its production and a mixed continuous filament yarn or staple fiber mixture.

In a two-component thread known from US-PS 35 58 419, the core consists of a special one Polyether-polyamide block copolymer. If such threads are incorporated into a carpet, so However, the antistatic properties of these threads are not sufficient to protect against electrostatic shock protection. As can be seen from a comparison of samples 3 and 5 of Table XIV of this publication, the The antistatic effect is significantly increased when the polyether-polyamide block copolymer forms the jacket.

From US-PS 36 39 807 an antistatic yarn is known which has a coated copper wire, wrapped around natural or synthetic fibers. The production of such a yarn is complex, because the copper wire is not crimped, textured and colored together with the non-conductive filaments can be. The known antistatic carpet yarn does not have sufficient electrical safety Hit, because the thin enamel coating, which serves as insulation, if it kinks or bends, like them occur constantly in use, can easily split off. The copper wire also bends easily and becomes stepped into the carpet during use, preventing it from developing its antistatic effect.

US-PS 28 45 962 and DE-OS 21 06 784 describe the use of antistatic textile threads, in which electrically conductive soot is distributed. However, these fibers have poor mechanical and physical properties Properties on and can therefore only to a limited extent to textile properties! processed, which is pointed out in US-PS 35 82 448, in the carbon black, electrically conductive Coatings on synthetic threads for antistatic purposes are described.

From GB-PS 8 16 965 a monofilament is known which consists of carbon, an inert filler such as S1O2, and a thermoplastic molding compound. This monofilament is said to be resistance wires or electrical conductors substitute. It can have an insulated coating made of a thermoplastic. The elongation of the monofilament is practically zero because of the presence of the inert filler. The monofilament breaks when it is bent or stretched and will not conduct because of the interruptions, even if an insulating coating

is provided. It is not specified that the insulating coating is made of a thread-forming thermoplastic is made. However, if it is not made from a thread-forming thermoplastic, it has none adequate durability for textile purposes. Also, the dimensions of the jacket and the conductive Monofilament not specified.

Compared to US-PS 35 58 419, the invention is based on the object of creating an antistatic thread, which is represented in a relatively small proportion in the yarn and yet offers long-lasting protection against static charge in a carpet.
This object is achieved by the characterizing features of claim 1.
Preferred embodiments of the invention are the subject matter of claims 2 to 4.

The invention also relates to the method specified in claims 5 and 6 and the im Claim 7 specified mixed continuous filament yarn or staple fiber mixture.

The core of the threads according to the invention preferably has a resistance of less than 0.4 10 ⁹ ohm / cm below a direct current potential of 2 IcV.

The antistatic threads according to the invention are particularly suitable for use in light-colored carpets. For such uses, the proportion of the sheath in the thread is at least 90% and is Coat matted so that the thread has a light reflectivity of more than 20% to the black To cover the core partially. For this purpose, the thread contains 2 to 7 percent by weight of titanium dioxide pigment A coat.

By a suitable choice of the polymer for the jacket, antistatic threads are obtained, which are as desired can be colored and puffed together under a wide variety of conditions and for purposes of use are suitable where the strength of the jacket is important.

Surprisingly, the antistatic properties of the threads according to the invention are due to the drawing not lost (see DE-OS 21 06 784, Example 3). It is also surprising that the invention Threads offer protection against electrostatic charge in carpets, although the non-conductive sheath at least does Makes up 50% of the threads. The conductive core can even make up less than 10% of the threads. The antistatic Effect occurs even at low moisture levels and when the antistatic threads are only in very high Small proportions are present in textile goods, mainly from other, conventional synthetic ones Fibers or filaments exist. Textiles with even less show good antistatic properties than 2% of the threads according to the invention, but preferably with more than 0.05% by weight. Another advantage of the threads of the invention consists in that they are dyed together with non-conductive threads can, if the polymer of the thread sheath is of the same polymer class as the polymer of the non-conductive Heard of threads.

Exemplary embodiments of the invention are explained below with reference to the drawing.

F i g. 1 is a schematic cross-section through a sheath and core thread according to FIG Invention;

F i g. Figure 2 is a schematic cross-section through an antistatic yarn made from a mixture of filaments according to FIG. 1 and non-conductive, synthetic threads.

In the case of the FIG. 1, the core 1 consists of electrically conductive carbon black 3, which is shown in FIG a polymer 4 is embedded, and is covered by the jacket 2, which consists of a non-conductive polymer surround.

According to FIG. 2, threads with the cross-section 5 shown in FIG. 1 are located under a substantially 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 more than 0.4 ■ IO 12} Ohm / cm, determined by contact with the thread surfaces at low DC voltages, e.g. B. 100 V or less. Homofibers made from such sheath materials also have resistances of more than 0.4 · 10 ¹² 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 application are referred to as "thread-forming".

Compared to the non-conductive sheath of high electrical resistance, the core of the threads has one low resistance and high electrical conductivity once electrical contact with has been made to him. The electrical contact with the thread core can be made either with the help of electrodes, which penetrate the jacket and come into direct contact with the core, or with the help of surface contact electrodes be produced, in which case one applies such a high voltage that the Current breaks through the thread jacket and thereby an electrical contact with the core is established comes. When using the latter method with surface contact electrodes, an increase occurs the direct current voltage to several hundred and especially to several thousand volts a sudden Increase in the amperage, as described below in the explanation of the test procedure. Once the electrical conductivity has been established in this way, the electrical current flows Current usually continues, even if the voltage is subsequently reduced, provided that only the contact of the Thread is not changed with the electrodes of the measuring device.

The low electrical resistance of the core of these threads is an indication that the core is whole measured thread length electrically related. Interruptions related to the core between the measuring electrodes make themselves noticeable by a higher electrical resistance, the sew on that of the coat. Occasional interruptions related to the core are for the antistatic behavior of the threads according to the invention is not particularly harmful. Preferably, however, the Core over the entire length of the fibers or threads according to the invention, regardless of whether they are staple fibers or if it is a continuous filament. It is essential that the core of the thread be of such a length of the thread is uninterrupted so that the thread in question together with other such antistatic Forms an effective antistatic network. Threads made in accordance with the test procedures described here having the specified level of electrical conductivity of the core provide an effective antistatic Protection.

The thread jacket can be made of any extrudable, synthetic, thermoplastic, 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 the condensation of diamines and dicarboxylic acids or polyamides derived from amino acids, the polyesters, especially those made from

Terephthalic acid or isophthalic acid and lower glycols such as ethylene glycol, tetramethylene glycol and Hexahydro-p-xylylenediol, as well as the polyacrylonitriles. These polymers can in a known manner with regard to their dyeability may be modified, e.g. B. by introduction, basic or acidic dye sites by copolymerization, to see their mixing and dyeing with other dyed or dyeable synthetic Fibers to facilitate.

The tensile strength properties and other physical properties of the threads according to the invention depend primarily on the polymer of the shell. Used for threads of high strength one as the material of the jacket polymers of higher molecular weight and those that become one stretch to a higher degree. Although undrawn threads according to the invention for some purposes can have sufficient strength, drawn filaments are preferred.

The thickness of the jacket must be sufficient to provide the core with the necessary protection, e.g. B. Strength as well Resistance to heat and abrasion, and to hide the core when required. in the 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, when the threads z. B. at high Temperatures need to be processed, e.g. B. by bulging in the hot gas or steam nozzle or by Texturing, it is essential that the thread jacket has a melting point so high that it is below the Processing conditions does not soften or melt. It is preferred to use for such purposes a higher-melting polymer, such as polyhexamethylene adipamide, in place of the jacket of polycaprolactam.

The thread core consists of a dispersion of electrically conductive carbon black in a thermoplastic Polymer. The core material is primarily taking into account the electrical conductivity and selected for processability. The soot concentration in the thread core can be 15 to 50%. With soot concentrations from 20 to 35%, which is preferred, a high electrical conductivity is obtained, while the Processability is still retained to a sufficient extent. The material for the core has preferably a resistivity of less than 200 ohm cm and more preferably less than 50 ohm · cm. The use of known, specially made for this purpose, electrically stronger conductive types of soot 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 polymers (which also have a correspondingly lower glass transition temperature) than Materials for the thread core are preferred over the stiffer, higher-melting polymers. That 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 the thread core from breaking and an interruption in the distribution of the soot particles), while the electrical conductivity in the The thread core and the finished thread are retained. It is not essential that the material of the thread core is different can be spun into threads by itself, and therefore the polymer does not need any for the thread core to be thread-forming polymer. The thread core polymer should, however, be among those used for spinning the polymer jacket required conditions to be heat-resistant and extrudable. Suitable polymers for the mass of the thread core, in which the soot particles are embedded, are z. B. polyamides, polyesters, acrylic polymers, Polyether, polycaprolactone and polyolefins (e.g. polypropylene, high and low pressure polyethylene). These polymers can be used to facilitate processing with other substances, such as oils or waxes, be mixed. Copolymers, such as those made from ethylene and vinyl acetate, can also be used.

The carbon black can be distributed in the fiber core polymer by known mixing processes. One must make sure to achieve such a uniform distribution of the carbon black in the fiber core polymer that the mass without excessive mixing and the associated decrease in electrical conductivity can be extruded.

For satisfactory spinning it is important to remove volatile substances from the polymers that make up the carbon black has been added to be removed prior to melt spinning. This can be during or after the collaboration of the carbon black with the polymer. It may also be useful to use such polymers, for. B. 16 hours

so to be dried under a low vacuum at 68 ° C. Furthermore, one uses the usual precautionary measures in order to to prevent oxidative decomposition during spinning by z. B. the oxygen in the polymer lines with the help of inert gas excludes etc. 'The cross-sectional area (which is directly related to the filament volume) of the electrically conductive The core of the composite thread just needs to be sufficient to give the thread the desired electrical power Resistance and may only need to be 0.5 percent by volume. The lower limit depends primarily on the processability to form sheath-core threads of sufficiently uniform Condition with still sufficient cohesion of the thread core with the low thread core volumes.

The spinning of the threads according to the invention can be used in conventional spinning systems for spinning

Sheath-core threads are made from two polymers, with the different properties of the two Components to be considered. The threads can easily be made using conventional spinning processes Produce polymers as they are, for. B. in US Pat. No. 2,936,482. Further instructions for spinning polyamides, see U.S. Patent No. 2,989,798.

The threads can be drawn by conventional methods; however, care must be taken avoid sharp corners that could break or damage the core of the thread. Generally served one of the claimed hot stretching process, in which the thread is added during the stretching is heated. This further softens the core material and makes it easier to stretch. The antistatic Threads can be plied with conventional, synthetic, undrawn threads and drawn together will.

The threads according to the invention can easily be produced with a tenacity of at least 1.5 g / den, which is completely sufficient if the threads are mixed with other threads as a component that is smaller in terms of quantity will. The threads preferably have an elongation at break of at least 10%, but less than 150%, on. The properties of the mixed textiles depend primarily on the properties of the other Threads off. For general purposes, the threads according to the invention have 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 cladding and core as well as combinations of these features. Due to the concentric arrangement one achieves the best protection and the best concealment of the thread core. The fineness of the thread core bears plays a major role in masking it, and fine-core threads can be found in dyed or patterned fabrics are used that otherwise have no other feature that hides the thread core. Furthermore can the core of the thread, if necessary, with the help of an opacifier in the form of cavities or in Mask the form of a white, solid, powdery matting agent, such as titanium dioxide, in the jacket. Out of round, z. B. multi-leaf cross-sectional shapes further contribute to the concealment of the thread core.

Variables that affect how the core of the thread is covered include the thickness and dyeability of the is Sheath, the ratio of sheath to core, the concentration of matting agents, such as titanium dioxide, in the Cladding and cavities that are created and then occur through separation between the cladding and core If the threads are oriented, their sheath and core are made from dissimilar polymers exist where z. B. 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 are filled with soot generally a light reflectance of less than 5%. Reflectivity values greater than than 20%, as can be achieved according to the invention, represent a very significant improvement because it does so it is avoided that light-colored fabrics take on a darker color by the threads according to the invention.

The threads according to the invention are able to use all types of textile materials, such as knitted fabrics, carpets, Woven and nonwovens to give excellent anti-static protection. You can use conventional Contain additives and stabilizers such as dyes and antioxidants. You can do all of them Kinds of textile processing operations such as crimping, texturing, washing, bleaching, etc. can be subjected. They can be combined with staple fiber yarns or filamentary yarns and as staple fibers or as continuous filaments be used.

The threads according to the invention can be used in the course of yarn production (e.g. during spinning, drawing, Texturing, plying, rewinding, yarn spinning) or in the manufacture of the textile materials with others Threads or fibers are united. Care should be taken that the antistatic threads as possible suffer few breaks. So z. B. when handling the relative lengths and shrinkage of the antistatic Threads and the other threads are coordinated to ensure good processability and the to achieve the desired bulkiness, subjectability, rotatability or texturability.

Description of the test procedures
Electric 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-filament bundle is just clamped between two electrodes two inches apart and sufficient voltage is applied to observe a flow of current (e.g., 1 to 4 kV). As soon as current flows, the voltage is set to 2 kV and the resistance is calculated according to Ohm's law R = E / l. If the current at 2 kV in a 5.0 cm sample z. B. 10 μΑ, the resistance for the three threads is 0.4 · 10 ⁸ ohm / cm. The resistance per thread is then 1.2 · 10 ⁸ Ohm / cm. In order to achieve a current flow in the above attempt, the voltage should be increased gradually in order to avoid a sudden increase in the current intensity, which could burn out the threads. Burnout can easily be determined visually (on broken, melted or charred threads), and such samples must be disregarded in the determination. The resistance of threads shorter than 5 cm can be measured by adjusting the distance between the electrodes accordingly.

55 reflectivity

The light reflectivity, namely the brightness or whiteness of the sample compared to a standard Magnesium oxide, is determined with a photoelectric reflectometer. A suitable device is that Photoelectric Reflectometer, Model 610, with a Green Color Mixing Filter (Catalog No. 6130), “Search Unit Model 610-Υ «, and a white lacquered work standard plate that is calibrated so that it has a reflectivity from 70 to 75% (Catalog No. 6162) available from Photovolt Corporation, 95 Madison Avenue, New York, N.Y. 10016. The electrically conductive thread sample on which the measurement is to be made is based on 5 "by 3" 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

The usual analytical method can be used to determine the soot concentration in the material of the thread core Use methods. A process suitable for polyethylene containing carbon black is described or can be taken from the ASTM test standard D-1603-68 can be derived. This is the thermogravimetric method that works for the Suitable for use in the absence of non-volatile pigments or fillers other than carbon black.

Percentage of the core in the thread

ίο The easiest way to determine the percentage by volume of the core is to use the cross-sectional area of the compares the black core with that of the entire thread by measurement under the microscope. This leaves can be carried out comfortably at approximately 400x magnification. With round threads you can easily determine the size calculate the ratio of the square of the core diameter to the square of the total thread diameter. The average of ten determinations is taken to compensate for any irregularities. at Threads with a non-circular cross-section, the calculation can easily be carried out on measurements made on microphotographic Recordings of thread cross-sections have been carried out at a known magnification.

If the polymer of the shell differs from that of the core by such a different solubility differs in that it can be removed by the action of solvents, you can determine the percentage of the Determine the core gravimetrically by dissolving the shell and adding the weight of the insoluble core to the Compare the weight of the original sample. So you can z. B. to dissolve a jacket made of polyhexamethylene adipamide Use formic acid from a polyethylene core.

Determination of the specific resistance
of the core material

The resistivity of the carbon black-containing core material is determined by measuring the DC resistance over a length of 5.08 cm of a 2.54 cm wide and 0.25 mm thick strip of film. Such films can easily be produced by pressing a powdery or tablet-shaped sample of the core material between two aluminum foils in a press heated above the melting point of the core material under a pressure of 1400 kg / cm ² for 1 to 2 minutes. After cooling, the aluminum foil is peeled off the sample foil, and strips 2.54 cm wide and about 6.35 to 7.62 cm long are cut out of the sample. The thickness of the foil is measured with a micrometer. A strip is sandwiched between two copper electrodes spaced two inches apart and the DC resistance is determined with an ohmmeter. The resistivity of the film in ohms cm is calculated from the reading on the meter 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 cm.

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 (non-volatile carbon 98%, volatile substances 2%, particle size 30 ιτιμ, lowest specific electrical resistance in the dry state), available from Cabot Corporation, 125 High Street, Boston, Massachusetts 02 110 , UNITED STATES. This soot is described in the technical reports "S-8" and "1518/173" from the company mentioned. The carbon black dispersion is prepared by adding the carbon black at 120 ⁰ C with high-pressure polyethylene (density 0.916; "Alathon the Applicant 2821"; melt index 23), grinding the mixture in the 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 with a density of 0.916 and a melt index of 11.9 on its own or im

so mixture with 15 with 40% oil or wax.) The melted carbon black mixture is passed through a sieve with a Mesh size of 0.15 mm filtered and extruded. Press foils show excellent carbon black distribution and electrical conductivity with a resistivity of 12.7 ohm · cm. Using this' Materials for the core are sheath-core filaments, namely three monofilaments with a thread denier of 65 den, spun at a speed of 389 m / min, the total denier being kept constant and the

Volume of the core is reduced by changing the pumping speeds so 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 filaments at 200x magnification. A three-hole spinneret made of stainless steel is used, to which the polymers for the shell and the core are fed concentrically and individually until they emerge at the front surface 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 spun with a thread denier of 65 denier. Then they are drawn at a speed of 183 m / min to a maintained at 150 ⁰ C, curved hot plate to the 3,06fache. The physical and electrical properties of the yarns are shown in Table 1.

Table I.

Sample no.

Core volume,% 50 40 25th 18th 12th Thread titer.den 21.4 20.6 21.4 21.2 19.9 Strength, g / den 1.5 1.9 2.4 2.8 3.4 Elongation at break,% 26.2 36.4 30.3 54.7 57.4 Initial modulus, g / den 15.3 17.9 25.1 20.3 25.2 Electrical resistance χ ΙΟ ⁹ , Ohm / cm / thread) - 0.98 2.64 1.57 5.24 Breakdown voltage, kV - 1.6 3.4 3.4 4.6 Electrostatic charging capacity of the carpet, kV (according to example 2) 2.0 3.0 2.8 3.0 2.6

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

The sample carpets in Table I are made from a commercially available 204-thread bulk carpet yarn Polyhexamethylene adipamide with a total titer of 3700, consisting of three-leaf continuous filaments, made with a pile height of 1.27 cm. A strand of electrically conductive thread (about 0.56 percent by weight) is pinned with the carpet yarn when unwinding and then used to make nubs. the Visibility of the electrically conductive threads in the carpet decreases with decreasing thread core volume noticeably off.

25 Example 2

Production of the thread jacket polymer

A stainless steel vessel is charged with 317.5 kg of an aqueous solution which is 50 percent by weight Contains hexamethylenediammonium adipate, whereupon 721 g of a 10 weight percent solution of manganese l) hypophosphite [Mn (H2PO2) 2] in water, 70 g of 25 percent strength by weight acetic acid and 100 ml of a 1 l, 2 percent strength Silicone antifoam adds. The batch is evaporated to a solids content concentrated by 75 percent by weight and transferred to a stainless steel autoclave equipped with a stirrer. The air is displaced from the autoclave by inert gas and the contents are heated to 200 ° C up to a pressure of 17 at heated. 14.83 kg of a 49 percent strength by weight aqueous titanium dioxide slurry are then added, with stirring to. The mixture is heated further until the temperature reaches 273 ° C. and then the pressure is gradually released Atmospheric pressure. The polymerization is continued according to Example 1 of US Pat. No. 2,163,636. To The polymerisation reaction is terminated by the molten polymer in the form of 6.3 mm strands extruded. 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:

Relative viscosity 43.5

(NH ₂ ) 46.0 equivalent per 10 ⁶ g

TiO ₂ 5.04%

Mn (H ₂ PO ₂ J ₂ 0.048%

Thread core polymer

50 composition

Polyethylene 70 percent by weight

Electrically more conductive
Carbon black according to Example 1 30 percent by weight

55 polyethylene

High pressure polyethylene (density 0.916; melt index 23 according to ASTM D-1238) manufactured by E. I. du Pont de Nemours and Company, for injection molding. The polyethylene contains 50 ppm of antioxidants in order to reduce its To improve heat and aging resistance.

Manufacturing

A 3.7-1 capacity two-blade dough mixer is charged with 1905 g of polyethylene and 816.5 g of carbon black. The whole is mixed for 30 minutes at 140 ^° C., extruded, sieved through a sieve with a mesh size of 0.15 mm and shaped into tablets.

The product has the following properties:

Specific resistance

(a film cast at 180 ° C) 2.9 to 4.2 ohm cm
Soot content 30.2%

Moisture content 0.4%

If the moisture content is higher than 0.1%, the tablets should be dried in vacuo ^{at 70 ° C. for 24 hours before spinning.}

The spinning

The polymers for the shell and the core are placed in a screw melt spinning machine Use of the spinneret arrangement shown in US Pat. No. 2,936,482 for concentric sheath-core threads spun.

The jacket polymer is processed at a throughput rate of 19.8 g / min (calculated from the capacity and speed of the pump) and the core polymer with a throughput rate of 0.7 g / min (calculated from the capacity and speed of the pump) fed so that you get a concentric arranged composite thread, 96 percent by volume of sheath and 4 percent by volume of core consists. During spinning, the temperatures of the polymers for the jacket and the core in the Screw melter set as follows:

Zones of the temperature of the temperature of the

Melted screw shell polymer core polymer
device "C ° C

Above 149 120 center 285 222 Below 288 265

The spinning block temperature is 293 ° C. The filling funnels for the two polymers are filled with inert gas flushed through.

The relative viscosity of the jacket polymer when it emerges from the spinneret (during free fall) is 56; the increase in relative viscosity is the result of further polymerization of the dried polyhexamethylene adipamide in the screw melter. The spinning speed is 814 m / min.

The spun yarn collected is gray and has the following properties:

Finishing on the yarn ~ 1.0%
Core, volume percentage 4

Coat, percent by volume 96

Titer of the spun bundle, the 60th

Number of threads per bundle 3

Reflectivity 37 to 40%

The stretching

The electrically conductive dreifädige yarn 60 is stretched in the draw-twister at a winding speed of 366 m / min and a shoe temperature of 180 ⁰ C to 2.7 times.
The drawn yarn has the following properties:

Common puffing

A strand of a 4-cavity hollow filament polyamide yarn of 3400 denier, as described in British patent specification 12 92 388, 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. The common bulking is carried out by the yarn is passed through a operated under a pressure of 8.44 kg / cm ² at 240 ⁰ C bulking jet of the type described in Belgian Patent Specification No. 5 73 230 to give filaments having a random, three-dimensional, curvilinear Gathering with alternating S and Z twist

Thread count 3 Strength, g / den 3.8 Elongation at break,% 35 Modulus, g / den at 10 percent strain 13th Electrical resistance of the Core bundle 1.8 x 10 ⁷ ohms / cm Reflectivity 34%

receives. 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 ² , fabric density 4 mm, 7 stitches per 2.5 cm), made from yarns that contain the electrically conductive threads (sample) and from yarns, which do not contain any electrically conductive threads (control), with a commercially available polypropylene nonwoven as a carpet base, and which are rubberized with conventional latex, provide the following values for the electrostatic charging capacity at 20% relative humidity and 2 Γ C:

Electrostatic Charging _{] 0}

ability of the carpet

Sample (according to the invention) 1.5 to 2, OkV

Comparative sample 10.2 to 11 kV

This test corresponds to the AATCC test standard 134-1969 with by the Carpet and Rug Institute in September Changes made in 1971.

In the raw carpets and the shine-dyed carpets, the three-ply 20-denier strands result electrically conductive threads have a very faint bluish tinge. Dyed carpets made from bulky continuous filament yarns, which contain electrically conductive threads show no difference in most single-colored shades and only minor differences in certain monochrome light colors, e.g. B. yellow, orange and pink if they can be compared with the control carpet.

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

Example 3

This example shows that care must be taken to ensure that the threads according to the invention when Stretching does not lose conductivity.

There are threads with an eccentric sheath-core arrangement with a sheath made of polyhexamethylene adipamide, which has a relative viscosity of 44 and contains 0.3% T1O2, and a core made of polycaprolactam (relative viscosity 45; 31.8 equivalents of NH2 end groups each 10 ⁶ g) spun with a carbon black content of 20%. 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. If the yarn is "hot drawn" without a pin on a curved heating plate at 160 ^° C., there is practically no increase in resistance. It is believed that when the yarn is heated in a heated drawing zone during drawing, the core is softened to such an extent that breakage of the core or an interruption in the distribution of the carbon particles required for conductivity is avoided.

Table Il

Draw ratio electrical resistance

of the core ohm / cm / 3 threads

of the core

1 (undrawn) 0.6 10 ⁸

1.5 2.4 · 10 ¹²

3.0 2.0 · 10 ¹⁴

3.0 (hot drawn) 2.75 · 10 ⁹ *)

*) Calculated from individual determinations on the three threads.

55 Example 4

Sheath polymer

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

Core polymer
Polycaprolactam with 22% electrically conductive carbon black according to Example 1.

Manufacturing

A predispersed slurry of 22.680 kg of electrically conductive carbon black, 86.180 kg of caprolactam and 83.910 kg of distilled water is prepared in a mixing vessel with stirring at 50 to 55 ° C. 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 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 is gradually released from 17.6 kg / cm ² _{to atmospheric pressure within IV 2} hours (relaxation period). The polymer is then extruded as a continuous band at 278 ° C., cooled with water and cut into flakes 3.2 mm in size. 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 has been extracted. The polymer is dried in vacuo (635 mm Hg) until the moisture content is less than 0.3%. The flakes are melted again, extruded, sieved through a sieve with decreasing mesh sizes (0.6 to 0.074 mm) and pressed 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 jacket and the core are in a combined spinning and stretching machine a winding speed of 1372 m / min (calculated from the speed of the winding roller in Rpm) spun and drawn together.

The jacket polymer is fed at a throughput rate of 29.7 g / min (calculated from the titer in spun state and the winding speed) and the core polymer with a throughput speed of 6.7 g / min (calculated from the linear density in the spun state and the winding speed) fed, so that a concentric sheath-core thread is formed, which is 81 percent by weight (calculated from the throughput speeds) from the jacket and at 19 percent by weight (calculated from the throughput speeds) consists of core. When spinning, the temperatures in the screw melting device set as follows:

Screw temperature of the temperature of the

Melting zone shell polymer core polymer

° C ° C

Above 249 206 center 281 250 Below 289 265

The spinning block temperature is 290 ° C. The yarn is powered by steam using a Stretching nozzle and electrically heated rollers (16 wraps) kept at 180 ° C stretched three times.

The drawn yarn is black and has the following properties:

Number of threads per bundle 1 Titer den 19.02 Overall finish on the Yarn,% 1.83 Electrical resistance of the core 1.3 x 10 ⁹ ohms / cm 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 of 30.
Core polymer

Manufactured according to example 2.

to

Spin

The shell polymer and the core polymer are according to Example 2 at a speed of Spun together at 787 m / min. The jacket polymer is with a throughput rate of 36.3 g / min (calculated from the speed and capacity of the pump) and the core polymer with a throughput speed 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 the jacket and consists of 4 percent by volume of core, determined on enlarged cross-sectional images.

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

Melting screw temperature of the temperature of the

device Manielpolymerisats core polymer

⁰ C ⁰ C

Zone 1 286 114 (top) Zone 2 284 184 (center) - 242 (below)

15th 20th

The spinning block temperature is 292 ° C.

A three-thread yarn of 60 denier is spun.

Stretch

The dreifädige 60-the sheath-core yarn at a speed of 415 m / min at a 97 ⁰ C hot heating shoe by 3.8 times stretched.
The drawn yarn has the following properties:

30th

10 «

This sheath core yarn is used together with a commercially available 34-thread polyester yarn of 150 denier in textured by a false twist texturing machine. The jointly textured yarn (a strand of three-thread sheath core yarn of 17.2 denier with a skein of 150 denier polyester yarn) becomes a »Swiss Pique «· Double knitted fabric processed. This knitted fabric is dyed and finished using known methods. After washing 30 times, the knitted fabric is tested in an electrostatic test device (electrometer, model E 525, from Presco Scientific Company) and compared to a control knitted fabric made from the same only Polyester yarn has been produced under the same conditions.

Titer den 17.2 Thread count 3 Electrical resistance of the core, Ohm / cm / thread 2.66 Strength, g / den 5.3 Elongation at break,% 21.5 Initial modulus at 10 percent Elongation, g / den 43.2

Electrostatic charge on the

Knitted fabric, V

after 0 seconds after 120 seconds

50

Trial fabric 400 380

Comparative knitted fabric 2750 2550

This results in good electrostatic protection of the knitted sample.

Example 6

A three-thread yarn of 60 denier is produced from the polyhexamethylene adipamide used in Example 2 as the polymer for the sheath and the polycaprolactam used in Example 4 with a carbon black content of 28% as the material for the core. Threads which consist to 96 volume percent of cladding and 4 volume percent of the core, will be called at a 180 ⁰ C, the curved hot plate (61 cm) to 3.0 times stretched. The yarn then has the following properties:

65

11th

23 37 103 Bundle titre, den 20.2 Strength, g / den 3.18 Elongation at break,% 49.1 Initial modulus, g / den 24.4 Electrical resistance of the core, Ohm / cm / thread 1.77 10 ⁹ Reflectivity,% 32

Electrostatic Reflection Charging capacity capital of the carpet of the carpet kV *) ° / o

Common puffing

The electrically conductive yarn is bulked according to Example 2 together with a 68-thread, base-dyeable continuous hollow thread carpet yarn made of polyhexamethylene adipic acid amide with a titer of 1225 denier and made into carpets with flat knobs with a pile height of 6.35 mm and a weight per unit area of 0.475 kg / m ² processed as described in Example 2.

The reflectivity and electrostatic charging capacity of shine-dyed carpets are compared to the corresponding properties of control carpets that do not have electrically conductive yarn contain.

Sample 1.5 to 2.4 65

Compare 8.6 to 9.8 75

*) As in example 2.

The visual rating of the carpets is consistent with the measured reflectivity.

Example 7

Threads (4 strands with a spun denier of 60 denier, 3 strands) with a polyamide sheath and a Polyethylene cores according to Example 2 made for use as staple fibers have the following Characteristics:

Finishing on the yarn,% 0.43

Weight percent core 3.5 _t

Weight percent coat 96.5

Carbon content of the core,% 32.3

Reflectivity, ⁰ / © 39
Electrical resistance of the

Core bundle (12 threads) 2.0 x 10 ohms / cm

The spun yarn is stretched by 8 strands combined in a Versuchsverstreckungsmaschine and are drawn at a winding speed of 210 m / min at a hot shoe temperature of 180 ⁰ C to 3.0 times.

The drawn yarn has the following properties:

Bundle titre, den 690 Thread count 96 Strength, g / den 4.72 Elongation at break,% 18.5

This electrically conductive yarn bundle is cut into pieces approximately 16.5 cm long and, during carding, 0.6.2% and 5%, respectively, of commercially available carpet staple fibers made of polyhexamethylene adipamide are added. The blends are made into two-strand spun yarns of 2.4 cotton with 3.5 Z twists and 3.5 S twists per 2.54 cm under normal staple conditions. The yarns are heat set in the autoclave and then processed into carpets with cut pile (Elektoralwollstil) with a basis weight of 1.19 kg / m ² , a fabric density of 3.96 mm and a pile height of 1.90 cm with a polypropylene base and with commercially available latex rubberized. The carpets are washed and dyed in a conventional manner with a mixture of three commercially available yellow, red and blue acid dyes, respectively.

The dyed carpets give the following values for the electrostatic charging capacity in the shudder test at 20% relative humidity and 21 ^{0 C:}

Ratio of antistatic fibers to basic fibers

Electrostatic charging capacity of the carpet 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 when applying the invention. Every sample has three threads per strand, and the carbon black is the same as in Example 1.

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

Sample B is similar to Sample A; however, the filaments have a three-leaf cross-section with a modification ratio from 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 contains, and a core, which consists of 40% polypropylene, 20% polyethylene, 10% a commercially available elastomeric copolymer of ethylene, propylene and a non-conjugated diene and 30% off There is soot.

Sample D consists of threads with a sheath made of commercially available polypropylene and a core like that Sample A.

Sample E has the same jacket as sample D, while the core is made from a commercially available polycaprolactone resin with a carbon black content of 30%.

Sample F has a jacket made of polyhexamethylene adipamide with a titanium dioxide content of 5% and a core made of a commercially available polypropylene resin with a carbon black content of 25%.

Sample G has a jacket made from the same polypropylene as Sample D and a core made from a commercially available one available polyethylene ether resin with a carbon black content of 26%.

Sample H is a non-antistatic control sample with a polyamide jacket, as in Sample A, and one Core made of the same polyethylene resin, but without carbon black.

The properties of the threads of these samples are shown in Table 111.

Table IH

Sample ver Titer strength fracture At first Core portion Reflection Electric stretching strain module Volume percentage capital Resistance of the relationship (Cross-section) of the yarn Core yarn 10 ⁸ the g / den % g / den % Ohm / cm / thread

A. 2.77 21.6 2.65 68.4 21.6 <10 28.5 1.2 B. 2.7 21.1 3.00 81.8 22.1 - 35 0.97 C. 3 110.6 2.19 62.8 14.2 3 49 3.54 D. 2.26 42.3 3.69 126 28.6 7.5 11th 3.54 E. 2.0 104.4 1.72 150 14.7 7.4 12.5 0.15 F. 2.5 33.3 2.49 34.2 17.6 7.5 31.6 11.8 G 2.0 55.7 3.29 108 28.7 15th 11th 0.12 H 2.70 19.1 3.87 34.5 23.6 4th _ > 10 ⁷

1 sheet of drawings

Claims (7)

Patent claims: 1. Antistatic synthetic two-component core-sheath type carpet thread having a denier of less than 50 denier, consisting of an endless, electrically non-conductive sheath of a synthetic material thermoplastic thread-forming polymer, which has a core made of a synthetic thermoplastic Surrounds polymerizate and occupies at least 50% of the thread cross-sectional area, characterized in that that the core is 15-50 in weight percent in the thermoplastic synthetic polymer contains dispersed, electrically conductive carbon black, is itself electrically conductive and has a direct current potential of 2 kV has an electrical resistance of less than 0.4 χ 10 "ohms / cm and the ι ο coat is molecularly oriented. 2. Thread according to claim 1, characterized in that the jacket has at least 80% of the thread cross-sectional area occupies and the electrically conductive core contains more than 20 percent by weight of carbon black. 3. Thread according to claim 1 and 2, characterized in that the jacket is matted and the thread is a Has light reflectivity greater than 20%. 4. Thread according to claim 1 to 3, characterized in that the polymer of the thread core a has a lower melting point and a lower glass transition temperature than the polymer of the thread jacket. 5. A method for producing the synthetic antistatic two-component threads according to claim 1 to 4 by composite spinning of two synthetic thermoplastic polymers with different electrical conductivity, the polymer for the thread jacket being thread-forming and the proportion of this Polymerisats is at least 50 percent by volume, as well as collecting the spun threads, characterized in that that the material for the electrically conductive thread core is an electrically conductive soot in Polymer containing dispersion and an electrically non-conductive material for the thread jacket Polymer used and the threads then stretched under heating so much that they have a strength of at least 1.5 g / den. 6. The method according to claim 5, characterized in that there is a mass with a core for the core electrical resistivity of less than 200 ohms / cm is used. 7. Mixed continuous filament yarn or staple fiber mixture, characterized in that it is made of electrically non-conductive synthetic filaments and less than 20 percent by weight of filaments according to claim 1 consists.