Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/02—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/18—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds from polymers of unsaturated nitriles, e.g. polyacrylonitrile, polyvinylidene cyanide

Definitions

• the invention relates to a continuous process for the production of crimped, highly shrinkable threads and fibers from acrylonitrile copolymers with at least 40% by weight of acrylonitrile units.
• a “continuous process” is understood to mean that the threads are spun, drawn, crimped and optionally cut into staple fibers in one operation without interruption using the dry spinning method.
• Acrylic fibers are usually manufactured using wet spinning, dry spinning and melt spinning technologies. While continuous processes have become known in the production of acrylic fibers by the wet spinning and melt spinning technology, for example the wet spinning process according to Textile Technology 26 (1976), pages 479-483 or the melt extrusion process according to DE-OS 26 27 457, which are not subject to any restrictions subject to the tape weights is up to only a continuously operating process for the production of acrylic fibers after the dry spinning process has become known, which can only be used for multifilament yarns with low strip weights, so-called acrylic silk, and under which certain conditions must be met, in particular a high viscosity of the spinning solution (US Pat. No. 2,811,409 ). This process is not suitable for the production of acrylic cables with high tape weights. It is also not suitable for the production of shrink threads and fibers.
• Highly shrinkable threads and fibers are understood to mean threads and fibers with a shrinkage of more than 35%. Such fibers are produced at low degrees of stretching and at low drawing temperatures (DE-OS 1 435 611 and 2 504 079).
• the dry spinning process is therefore interrupted before drawing, the spinning material is collected in cans, from which it is then fed to further post-treatment (Bela von Falkai, Synthesefaser, Verlag Chemie, Weinheim / Deerfield Beach, Florida / Basel (1981), p. 204 -206; R. Wiedermann, acrylic fiber spinning and post-treatment processes in man-made fibers / textile industry, June 1981, pp. 481-484, in particular p. 482 left column above).
• the object of the present invention to provide a continuous process for the production of highly shrinkable acrylic fibers by the dry spinning method, in which all process stages from the formation of the thread to the fiber ready for dispatch in one working process without any interruption or intermediate storage, and which can be applied to spinning cables with high strip weights.
• the preparation of the spinning solution should be able to be integrated into the continuous process.
• this object can be achieved if a spinning solution of a certain viscosity is used, the proportion of the solvent in the spinning material in the spinning chute presses below certain values by the type of solvent removal, which provides the threads with a preparation prior to stretching which is a lubricant and contains an antistatic, preferably an aqueous preparation, but the water absorption (moisture) of the threads remains below certain values and does not bring the threads into contact with any other solvent extraction liquid before and during stretching.
• the spinning delay of the process is preferably greater than 2, in particular 2 to 12.
• the spinning solution at 100 ° C. has a viscosity of 15 to 50 falling ball seconds
• the solvent content of the threads when leaving the spinning shaft is max. 5% by weight, based on the fiber solids content
• the draw ratio is 1: 2 to 1: 3.5.
• the threads preferably do not come into contact with a further extraction liquid for the spinning solvent during the entire process.
• Spinning delay V is defined as the ratio of take-off speed A to ejection speed S:
• the method of the invention it is possible to produce high-shrinkable spinning tow with a tape weight of 100,000 dtex and more with such a low content of residual solvent that after the hot stretching and your subsequent crimping process, which is carried out at a maximum of 100 ° C, the residual solvent content in the finished fiber or in continuous cable is clearly below 5 wt .-%, without the spinning material having come into contact with an extracting agent for the spinning solvent, apart from the water content of the spinning preparation.
• the threads obtained according to the invention have fiber strengths of 1.5 cN / dtex and more.
• Suitable acrylonitrile copolymers are all acrylonitrile copolymers spinnable into so-called acrylic fibers or modacrylic fibers, preferably acrylonitrile copolymers with at least 85% by weight of acrylonitrile units.
• the polymers are known.
• the spinning material i.e. the spinning cable leaving the spinning shaft has a residual solvent content of less than 10% by weight, in particular between 2 and 5% by weight, based on the dry fiber weight, because spun material with higher residual solvent contents, for example of dimethylformamide, adheres during subsequent stretching Godets at belt temperatures around 100 ° C or there is an undesirable cold expansion of the material ie an uneven and imperfect hiding under not exactly defined conditions. It is also necessary to wet the spun material before stretching, while still hot, preferably at the end of the spinning shaft, either inside or immediately behind the spinning shaft, with a preparation which contains a lubricant and an antistatic, and to stretch it directly without cooling.
• the lubricant allows perfect stretching of even thick cables of 100,000 dtex and more.
• the preparation can also contain water as an ingredient, but care must be taken that the cable does not absorb more than 10% by weight of moisture. If the cable contains large amounts of water, it cools down strongly and unevenly and during the subsequent stretching, the cable shows tears or wrap formation on the godets.
• Suitable lubricants are glycols, their derivatives, silicone oils, ethoxylated fatty acids, alcohols, esters, amides, alkyl ether sulfates, and mixtures thereof.
• the preparation can contain a corresponding commercially available preparation, for example a customary cation-active, anion-active or nonionic compound, such as a long-chain ethoxylated, sulfated and neutralized alcohol.
• the preparation expediently has a temperature of 50-90 ° C. in order to prevent the hot thread sheet from cooling.
• the manhole tapes spun by a spinning machine with, for example, 20 spinning chutes with a total titer of 100,000 dtex and more are prepared, bundled and fed to an inductively heatable roller pair via a take-off device.
• a clamping point is produced by looping the pair of rollers one or more times, possibly using a lead roller.
• a coolable withdrawal quintet or septet serves as the second clamping point, which is arranged at a distance of approx. 3 m from the inductively heated pair of rollers and causes the cable to be stretched by a correspondingly higher speed.
• the cooling of the rollers on the second stretching element is necessary in order to achieve the desired shrinkage level in the subsequent crimping process.
• Septet rollers which are heatable at the beginning and coolable at the end have proven to be preferred stretching members.
• a tube heated with superheated steam or hot air can advantageously be integrated between the septet rollers.
• spinning take-off speeds of 50-100 m / min are completely sufficient to keep the residual solvent content in the spun material clearly below 10% by weight, so that maximum degrees of speed of 350 m / min are achieved at stretching levels of up to 350%, which are technically manageable are.
• the crimping is preferably carried out in a stuffer box.
• the crimped cable is then cut into staple fibers and pressed into bales.
• the process is particularly suitable for the production of spun-dyed threads and fibers by adding soluble dyes, in particular cationic dyes or pigments, to the spinning solution, because when the color is changed due to the special work-up, considerably less rejects are obtained.
• solution polymerization in the spinning solvent used e.g. Dimethylformamide upstream, so that after a corresponding concentration and monomer removal via thin-film evaporator, a continuously working process for the production of high-shrinkable acrylic fibers is achieved for the first time after a dry spinning process with the highest possible degree of automation.
• the spinning solvent used e.g. Dimethylformamide upstream
• a great advantage of the method is that no washing process is required, which means that the drying process previously required is also eliminated.
• the fibers obtained according to the invention have a density of over 1.165 g / cm 3 and are vacuole-stable. Since the high-shrink cable can also be crimped in the dry state, an extraordinarily high adhesion and a very high carding speed, which is not otherwise known for acrylic high-shrink fibers, usually over 100 m / min, is achieved in the secondary spinning mill. Another advantage of dry heat drawing is the very good stack distribution with extremely low short and long fiber content. All of these advantages are not achieved in conventional processes for producing high-shrinkage fibers as a result of intermediate washing processes for removing spinning solvents.
• dimethylformamide (DMF) are mixed in a kettle at room temperature with stirring, with 300 kg of an acrylonitrile copolymer made from 93.6% acrylonitrile, 5.7% methyl acrylate and 0.7% sodium methallylsulfonate with a K value of 81.
• the suspension is pumped via a gear pump into a spinning kettle equipped with an agitator. Then the suspension is heated in a double-walled tube with steam of 4.0 bar. The dwell time in the tube is 5 minutes.
• the spinning solution which has a temperature of 138 ° C at the tube outlet and a viscosity of 19 falling ball seconds, measured at 100 ° C, is cooled to 90 ° C after leaving the heating device, filtered and fed directly to a spinning system with 20 spinning shafts.
• the spinning solution is dry spun from 1264-hole nozzles, nozzle hole diameter 0.2 mm, with a take-off speed of 50 m / min and a spin delay of 2.4.
• the dwell time of the spinning threads in the spinning shafts is 5 seconds.
• the shaft temperature is 200 ° C and the air temperature is 360 ° C.
• the throughput of air is 40 m 3 / h for each shaft.
• the spinning material with a total titer of 343,000 dtex, which still has a residual solvent content of 2.8% by weight, based on the solids content, is heated with an 80-90 ° C, immediately after leaving the spinning shafts and before entering the tube connected behind it.
• aqueous, oil-containing, antistatic preparation so wetted that the oil content of the threads 0.16 wt .-%, the antistatic content 0.04 wt .-%, and the moisture te 1.1% by weight, based on the fiber solids content.
• the preparation is dosed via gear pumps.
• the tube connected behind the spinning chutes is fed with hot air at 300 ° C in countercurrent to the direction of the thread to remove the DMF.
• the warm cable is sent over a roller septet heated inductively to 145 ° C.
• the cable assumes a strip temperature of 85 ° C, measured with the KT 15 radiation thermometer.
• the cable is then stretched by 250%, with a stretch septet with coolable rollers serving as the second clamping point.
• the strip temperature after the stretching process is 39 ° C.
• the cable is crimped in a stuffer box and subjected to cold air at room temperature in a U-tube-shaped boot in order to maintain the shrinkage level.
• the high-shrinkable acrylic cable is cut into staple fibers 80 mm long and fed to a packing press.
• the high-shrinkable acrylic fibers produced in this way in a continuous process have a single fiber final titer of 5.0 dtex.
• the fiber cooking shrinkage, determined in boiling water, is 44.4%.
• the density before cooking is 1.174 g / cm 3 and after cooking at 1.171 g / cm 3 .
• the fiber strength is 1.8 cN / dtex and the fiber elongation is 70%.
• the fibers are vacuole stable and have a completely smooth, structureless fiber surface.
• the fibers could be processed on a high-performance card at 120 m / min.
• the short and long fiber content in the stack diagram is less than 2%.
• Table I shows the shrinkage behavior for spun material of the same total denier 343,000 dtex for different strip temperatures and degrees of stretch.
• the manufacture of the high-shrink fibers otherwise corresponded to the information in Example 1.
• a suspension according to Example 1 is in the spinning kettle with 1.18% by weight, based on solids, of the red dye of the formula: and 0.11% by weight, based on solids, of the yellow dye of the formula: added to achieve a crimson color and then, as described in Example 1, heated, transferred to a spinning solution and spun to crimson high-shrinkage fibers and aftertreated.
• the high shrinkage fibers have a single fiber end titer of 5.1 dtex.
• the fiber cook shrinkage was 44.8%.
• the density of the crimson high shrink fibers before cooking is 1.172 g / cm 3 and after cooking at 1.166 g / cm 3 .
• the fiber strength is 1.7 cN / dtex and the fiber elongation is 66%.
• the fibers could be processed on a high-performance card at 110 m / min.
• a suspension according to Example 1 was mixed with 0.04% by weight of carbon black, based on solids, 0.02% by weight of pigment red and 0.09% by weight of pigment yellow to achieve a beige color and as described in Example 1 , heated, transferred to a spinning solution and aftertreated. However, it was stretched 1: 3.5 times at a belt temperature of 100 ° C.
• the beige high-shrink fibers with a single final titre of 3.8 dtex have a boiling shrinkage of 35.3%.
• the fiber strength is 2.3 cN / dtex and the elongation is 50%.
• the density is 1.172 g / cm 3 before cooking and 1.165 g / cm 3 after cooking.
• the fibers could be processed on the high-performance card at 100 m / min.

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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)

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• 1982
  • 1982-07-06 DE DE19823225268 patent/DE3225268A1/de active Granted
• 1983
  • 1983-06-17 US US06/505,542 patent/US4508672A/en not_active Expired - Fee Related
  • 1983-06-24 DE DE8383106188T patent/DE3369352D1/de not_active Expired
  • 1983-06-24 EP EP83106188A patent/EP0098485B2/fr not_active Expired - Lifetime
  • 1983-07-05 JP JP58121120A patent/JPS5921713A/ja active Pending

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