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
  • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
  • D01F6/70—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyurethanes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
  • Y10S264/77—Processes of molding urethanes

Definitions

• This invention relates to a process for the preparation of spandex filaments of which elongation is temporarily lowered.
• spandex or rubber filaments offered great difliculty for proper tension control during their posttreatments such as spinning, knitting and weaving because of their very high elongation of above 300%, normally even higher than 500%.
• polyurethane spandex shows behaviours close to one point drawing different from rubber, the tendency being particularly conspicuous in the polyurethanes prepared with a low molecular diol serving as the chain extender, compared with the polyurethanes prepared with other chain extenders such as hydrazin, diamine or water. Furthermore it is found that the tendency is enchanced under elevated temperatures.
• the said polyurethane showing the behaviours of one point drawing for which a low molecular diol is used as the chain extender is found to possess the property to form far better spandex filaments of temporarily lowered elongation intended by the invention, compared with such polyuethanes prepared with other chain extenders, e.g., water, diamine and hydrazin. Still in addition We found substantially complete removal of solvent from the polyurethane filaments before the drawing to be highly effective for the preparation of the spandex filaments of which elongation is temporarily lowered. Those discoveries led us to the present invention.
• the object of the invention resides in the preparation of the spandex filaments of excellent properties and furthermore having an elongation temporarily lowered to around by the process which comprises dry spinning a spinning solution of a polyurethane elastic polymer in a heated spinning column and preparing spandex filaments having high elongation similarly to conventional spandex filaments, substantially completely drying the solvent in the subsequent drying step, drawing the filaments, heat setting the spandex filaments under tension, further cooling the same to at least below 50 C. and thereafter shrinking the same by 5-15 of the original length.
• a particular care should be taken to secure a sufiicient drying until the amount of the solvent remaining in the filaments after spinning and before drying is reduced to no more than 0.5 wt. percent to the filaments. Because, in case filaments containing more than 0.5 wt. percent of solvent are subjected to drawing, heat setting, cooling and thermal shrinking in accordance with the invention, admittedly fibers having an elongation of around 100% are obtained which, however, fail to perform sufficient shrinkage during the heat treatment at around 100 C. free of tension and consequently cannot regain the high elongation possessed before the drawing.
• prepared fiber had an elongation of 118%, but when treated in 100 C.
• the temperature employed for drying of the solvent in accordance with the invention should be above boiling point of the solvent but no higher than 200 C. With the drying temperature below boiling point of the solvent, drying efiiciency is poor, and such high temperatures exceeding 200 C. should also be avoided because at the temperatures close to the melting point of the filaments fusion among the mono-filaments tends to take place.
• the drawing temperature in accordance with the invention should be within the range of 80150 C., preferably 120150 C. Because, at temperatures below 80 C. the desired high speed drawing is inoperable, while at above 150 C. ideal one point drawing cannot be achieved, causing an uneven drawing effect. Furthermore, the draw ratio should be 26 times the original length of the filaments, for the reason that at a draw ratio less than 2 fibers of sufficiently lowered elongation cannot be obtained even after the heat setting, cooling and thermal shrinkage in accordance with the invention, and on the other hand with high draw ratios exceeding 6 and approaching the breaking point of the fibers, degradation in strength properties of the fibers is invited.
• the heat setting temperature should range 150200 C., preferably 160180 C. Heat setting at below 150 C. could achieve the intended effect with prolonged setting time when the drawing temperature was below the said level, but such is not an industrially recommendable procedure. Once again temperatures exceeding 200 C. being close to the melting point or" the filaments, setting at such high temperatures tends to cause objectionable fusion among the monofilaments even within a short time.
• the heat set filaments at below 50 C., preferably to room temperature, to stabilize the shrinking portions of the filaments formed when they are freed from tension, which were not heat set in the preceding step, and thereafter to shrink the filaments by 15% of the original length thereof.
• the purpose of this last shrinking is to prevent the occurrence of non-uniformity in properties of the products such as non-uniform denier and strength distribution when the elastic fibers of the invention are, for example, mix-spun, combined or subjected to other treatments with non-elastic fibers, such inuniformities being caused by the shrinkable portions present in the elastic fibers.
• the shrinkage should be by 5-15% of the original filament length.
• the spandex filaments thus prepared having an elongation of around 100120% and a tenacity of about 2.0 4.0 g./d. of the invention can be mix-spun, knit or woven with non-elastic fibers such as nylon and polyester using ordinary equipments for mix-spinning, knitting or weaving, without requiring the complicated tension control machine employed with conventional spandex filaments processing.
• the spinning solution of a polyurethane elastic polymer of the invention is fed into a spinning head by means of a gear pump and extruded into a heated spinning column through which a heated gas is passed, from a nozzle in the spinning head.
• the filaments whereby formed contain about 4 wt. percent to the spun filaments of the solvent remaining therein when they leave the spinning column.
• the same are then led to godet rollers via oiling rollers and guides.
• the filaments thus containing about 4 wt. percent of the solvent are further well dried by means of heated Nelson rollers for drying to have the remaining solvent content reduced to no higher than 0.5 wt. percent.
• the filaments are drawn between two rollers and heat set by means of heat setting Nelson rollers, followed by cooling by means of cooling rollers which are not heated but maintained at room temperature.
• the filaments are then slightly shrunk between two rollers and taken up onto a take-up machine.
• block copolymers consisting of the following three components: polymer diol of melting point no higher than 60 C. and molecular weight ranging SOS-5,000, preferably 800-3,000, and having terminal hydroxyl radicals; aromatic diisocyanate; and low molecular diol of molecular Weight ranging 50-200.
• polymer diol having terminal hydroxyl radicals include: polyethylene adipate, polyethylene propylene adipate, polybutylene adipate, polyhexamethylene adipate, polyethylene butylene adipate, polycaprolactam, polytctramethylene glycol, polypropylene glycol and polyethylene glycol.
• aromatic diisocyanate 4,4-diphenylmethane diisocyanate, 3,3,5,5'-tetramethyldiphenylmethane-4,4-diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate and the like are employed.
• any diol having a molecular weight ranging 50- 200 may be used as the chain extender, for example ethylene glycol, 1,4-butanediol, 1,6-hexanediol and the like are preferred.
• the polyurethane elastic polymers contemplated in the invention are prepared from aforesaid three components, viz., high molecular polymer diol, aromatic diisocyanate and low molecular diol. They may be prepared in accordance with accepted practices.
• One of the known means for their preparation comprises reacting a polymer diol with an aromatic diisocyanate to form a prepolymer in which the terminal radicals of the polymer diol are isocyanate group, adding thereto each suitable amount of the aromatic diisocyanate and a low molecular diol to form a polyurethane block polymer. It is also possible to mix the three components from the start and react them. Furthermore, those reactions may be performed in a solvent such as dimethylformamide, dimethylsulfamide or methyl isobutyl ketone, in the presence of a catalyst.
• polyurethane elastic polymers are the optimum starting materials for the spandex filaments of temporarily lowered elongation.
• spinning solutions those prepared by dissolving the above polyurethane elastic polymers in suitable solvents such as dim-ethylformamide, dimethylacetamide, tetrahydrofurane and dimethylsulfoxide are used.
• the spandex filament was used The properties of the spandex filaments obtained thus in at the ratio of one thread to 3 Strands 9 the mlxed y accordance with the subject invention are given in Table The Weavmg w operable employing conventlonal 1 below, from which it can be understood that the product g i g f ahspeclal t is characterized by its low elongation, high tenacity, high t i a g ave i g g Youngs modulus and surprisingly great elasticity com- 6.011 e an W1 0 e a me S pared with conventional Spandex filaments Also from l1ttle elasticity as woven, but when SUbJCCtCd to a serles of Table 1 it can be understood that the low elongation set post'treatmlcnts compnsing rekixation m hot .Water to spandex filaments return to the conventional spandex filag: r???
• the heat setting temperature should be no lower than 150 C. in order to perform the heat setting of the invention with good etficiency.
• EXAMPLE 1 A polyurethane elastic polymer synthesized by reacting polycaprolactam having a molecular weight of 1,700 and terminal hydroxyl radicals with 4,4-diphenylmethan-e diisocyanate and ethylene glycol at the molar ratio of 1.0:5.0:4.0 was thoroughly dried, drawn, heat set, cooled and shrunk in the similar manner as described in Example 1.
• spandex filaments 40 deniers
• filaments similarly prepared from a polyurethane elastic polymer obtained by reacting a prepolymer of polytetramethylene glycol having a molecular weight of 2,180 and 4,4'-diphenyimethane diisocyanate with ethylene diamine as the chain extender failed to exhibit sutficient low elongation set effect.
• the filaments were dried on Nelson rollers of 175 C. driven at a rate of 300 m./min. for 8 seconds to have a reduced dimethylformamide content of 0.37 wt. percent. Thereafter the filaments were drawn by 4 times between two rollers heated to 135 (3., heat set on heat-setting rollers of 180 C. which were driven at a rate of 1200 m./min. for 6 seconds, cooled to about 2223 C. on cooling rollers of 20 C. driven at a rate of 1200 m./min. for 3 seconds, and shrunk by 10% as they were taken up onto a take-up roller of 20 C. driven at a rate of 1080 m./min.
• spandex filaments having a denier of 38 had a tenacity of 2.60 g./d. and an elongation of 80%.
• the same filaments after the subsequent treatment in 100 C. water for 12 minutes free of tension, had a tenacity of 1.13 g./d. and an elongation of 390%, thus returning to the conventional spandex filaments of low tenacity and high elongation as they were before the treatments of the subject invention.
• the spandex filaments prepared under exactly same conditions to the above except that the 1,4- butanediol as the chain extender was replaced by hydrazine showed at 40 deniers a tenacity of 1.73 g./d. and an elongation of 340%, thus showing no low elongation set effect.
• the filaments were drawn by 3 times between two rollers heated to 145 C., heat set on heat setting rollers of 185 C. driven at a rate of 990 m./min. for 7 seconds, cooled on cooling rollers of 25 C. driven at a rate of 990 m./min. for 5 seconds, and further shrunk by 5% as they were taken up onto take-up rollers of 20 C. driven at a rate of 940 m./min.
• spandex filaments had a denier of 35 and an elongation of 101%.
• the filaments showed an elongation of 415%, thus exhibiting excellent elastic recovery.
• polyurethane elastic polymer is that obtained by the reaction of polyethylene propylene adipate having a molecular weight of 5005,000, 4,4- diphenylmethane diisocyanate, and ethylene glycol.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Artificial Filaments (AREA)

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Cited By (6)

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Citations (6)

• 1967
  • 1967-04-03 GB GB15197/67A patent/GB1159623A/en not_active Expired
  • 1967-04-03 US US627667A patent/US3476850A/en not_active Expired - Lifetime
  • 1967-04-05 DE DE19671660434 patent/DE1660434A1/de active Pending
  • 1967-04-05 FR FR101669A patent/FR1522611A/fr not_active Expired

Patent Citations (6)

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