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
  • D01F1/00—General methods for the manufacture of artificial filaments or the like
  • D01F1/02—Addition of substances to the spinning solution or to the melt
  • D01F1/10—Other agents for modifying properties
• • 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

Definitions

• the present invention relates to spandex in which particles of barium sulfate are dispersed. More particularly, the invention concerns an improvement in such a spandex wherein the spandex has a roughened surface and the barium sulfate particles have a very low isoelectric point. The invention also concerns a process for producing such spandex. The presence of the barium sulphate particles of low isoelectric point in the spandex provides unexpected and advantageous reductions in the tackiness of the spandex and improvements in the process for producing the spandex.
• Spandex is known to exhibit considerable tackiness compared to conventional non-elastomeric textile fibers.
• the filaments tend to stick to various surfaces and to each other, especially when wound up on a bobbin.
• Tackiness can cause excessive unwinding tension (referred to hereinafter as “take-off tension”) as well as frequent, large transients in the tension as the spandex is unwound from the package. Excessive take-off tensions and transients can cause yarn breaks during handling, fabric defects and other manufacturing difficulties, especially in making of knit fabrics.
• lubricating finishes are applied to spandex yarn and/or special agents are dispersed within the spandex.
• lubricating finishes include (a) metallic soaps dispersed in textile oils, such as those disclosed by Yuk, United States Patent 3,039,895, and (b) polyalkylsiloxanes, such as those disclosed by Chandler, U.S. Patent 3,296,063.
• the dispersion of certain metal soaps (e.g., stearates of calcium, magnesium or lithium) within the spandex for tackiness reduction is disclosed by Hanzel et al, U.S. Patent 4,296,174. Further reductions in the tackiness of the spandex would improve its handling characteristics, make its production more economical and enhance its utilization in various fabrics.
• barium sulfate among many other inert inorganic materials, has been disclosed for use in spandex, by for example, Bell et al U.S. Patent 3,386,942 and Imai et al, U.S. Patent 4,525,420. Barium sulfate is available commercially in several forms, purities and grades. Applicant now has found that the tackiness characteristics of the spandex can be modified very favorably by dispersing in the spandex particular barium sulfate particles having specific isoelectric properties.
• the present invention provides an improved spandex of the type that has a lubricating finish on its surface and barium sulfate particles dispersed within its volume.
• the barium sulfate particles have an isoelectric point in the range of 0 to 4, preferably in the range of 0.5 to 3.
• the barium sulfate particles amount to in the range of 0.3 to 5%, preferably 1 to 3%, of the weight of the spandex.
• the spandex containing the barium sulfate has a surface roughness parameter (defined hereinafter) of at least 75, preferably in the range of 100 to 200.
• the average pore size is in the range of 10 to 30 Angstroms and the BET surface area is in the range of 1 to 5 m 2 /g.
• the spandex contains titanium dioxide particles amounting to in the range of 1 to 5% of the total weight of the spandex and the lubricating finish is a polysiloxane amounting to in the range of 1 to 6% by weight of the spandex.
• the yarn is wound up on a cylindrical member to form a yarn supply package of low tackiness.
• the invention also provides an improved process for dry-spinning spandex, wherein a solution of a segmented polyurethane polymer in an organic solvent is mixed with additives and then dry-spun into filaments.
• the improvement comprises at least one additive being barium sulfate having an isoelectric point in the range of 0 to 4.
• the term "spandex” has its usual definition; that is, a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer composed of at least 85% by weight of a segmented polyurethane.
• fiber includes in its meaning staple fibers and continuous filaments.
• the chemical composition of a polymer of the spandex also may be abbreviated as illustrated by the following example, in which a polyurethaneurea made from poly(tetramethyleneether)glycol (“P04G”) having a number average molecular weight of 1800, methylene-bis (4- phenylisocyanate) (“MDI”) and a mixture of ethylene diamine (“EDA”) and 2-methyl-l,5-diaminopentane (“MPMD”) in a molar ratio of 90 to 10, is abbreviated as
• a spandex has dispersed within its volume barium sulfate particles having an isoelectric point in the range of 0 to 4, preferably 1 to 2.5.
• the barium sulfate amounts to 0.3 to 5%, preferably 1 to 3%, of the total weight of the spandex.
• the particles of barium sulfate may be coated with specific agents for special purposes.
• the particles can be coated with antimicrobial compositions such as those disclosed by Jacobson et al in U.S. Patent 5,180,585.
• the use of coatings on the barium sulfate does not detrimentally affect the spandex produced therewith, and such coated particles are intended to be included within the scope of the invention.
• the barium sulfate particles suitable for use in the present invention are small.
• the polymer of the spandex of the invention can contain conventional agents that are added for specific purposes, such as antioxidants, thermal stabilizers, UV stabilizers, pigments, dyes, lubricating agents and the like. Such agents are usually added to the solution of the polymer and become incorporated into the filaments during the dry spinning step.
• the barium sulfate additive in accordance with the present invention, can be incorporated into the filaments in the same manner as the other additives.
• the concentration of barium sulfate is typically in the range of 0.3 to 5% by weight of the spandex polymer.
• various types and grades of barium sulfate particles are known, such as barites or barytes ore, chemically pure barium sulfate, blanc fixe and the like, only barium sulfate having an isoelectric point in the range of 0 to 4 is suitable for use in the spandex of the invention.
• Barium sulfate particles with an isoelectric point in the range of 1 to 2.5 are preferred.
• the particular barium sulfate suited for use in the present invention represents a small fraction of all the barium sulfates that are available commercially.
• Natural barium sulfate the mined ore (also known as “barite” or “barytes") , contains several colored impurities. Some of these impurities can be removed by beneficiation of the ore through washing, tabling, jigging or floatation. Although the mined barium sulfate contains various impurities, such barium sulfate often can be used directly for drilling muds, the largest known use for the ore. Finely ground barite is used as a filler or extender for paints.
• Barite for pigment usually is "bleached" by treatment with acid and often also with a reducing agent to remove colorizing compounds. Chemically pure barium sulfate is also available for chemical reaction purposes. Still another commercially available barium sulfate is precipitated barium sulfate, also known as blanc fixe.
• 6 particles is typically in the range of 0.5 to 3 microns, with the largest particles (i.e., not more than 2% of the particle size distribution) being greater than 25 microns, preferably no greater than 15 microns.
• Conventional polymers used for preparing spandex by dry spinning are suitable for the spandex of the present invention. These typically are prepared by known processes in which a polyether-based glycol or polyester- based glycol is reacted with a diisocyanate to form an isocyanate-capped glycol which is then reacted with diamine chain extender to form the segmented polyurethane polymer.
• the polymer is dissovled in an inert organic solvent, such as dimethylacetamide (DMAc) , dimethylformamide, N-methyl pyrrolidone or the like.
• an inert organic solvent such as dimethylacetamide (DMAc) , dimethylformamide, N-methyl pyrrolidone or the like.
• the pH of the polymer solution is in the range of 9 to 12.
• the low isoelectric point (i.e., 0 to 4) of the barium sulfate particles for use in the invention the particles are very well dispersed within the solution and subsequently within the spandex.
• the polymer solution is dry-spun in conventional equipment through orifices into a shaft. Heated inert gas passes through the shaft to assist solvent evaporation from the surface of the formed filament as the filament passes through the shaft.
• Filaments from multiple orifices are twisted together to form a multi-filament yarn.
• Lubricant can be deposited on the surface of the filaments by a conventional finish roll or by being co-spun with the filaments from the polymer solution. Thereafter, the thusly dry-spun filaments (i.e., spandex) are wound up on a cylindrical member to form a yarn supply package (e.g., a pirn, bobbin, cake) .
• a yarn supply package e.g., a pirn, bobbin, cake
• spandex filaments are quite tacky.
• Polyether-based spandex usually is more tacky than polyester-based spandex.
• Clear spandex, derived from polyether glycols is the tackiest.
• spandex yarns are well known.
• "LYCRA" spandex is manufactured and sold by E. I. Blanc fixe, usually is prepared by mixing aqueous solutions of barium sulfide and sodium sulfate under controlled conditions in order to produce a precipitate of uniform particles of pigmentary fineness.
• barium sulfate particles commercially available, only particles having an isoelectric point of no greater than about 4 (e.g., some of the blanc fixe grades) were found suitable for use in the present invention.
• These particular blanc fixe particles were unexpectedly better than all the others in reducing the tackiness of dry-spun spandex and in providing more efficient operation of the dry-spinning process.
• Isoelectric point determinations are made with conventional instruments.
• the isoelectric point is defined as the concentration of hydrogen ions and other ions, usually expressed as a pH, at which the particles have no net charge and the zeta potential is zero.
• the procedure is as follows. A 20-gram sample of barium sulfate powder in 200ml of a 0.001N potassium nitrate is titrated with 3M potassium hydroxide or 2M nitric acid (depending on whether acid or base is needed for the titration) . Prior to the titration, the sample is thoroughly dispersed in the liquid by means of a sonic mixer, a Sonicator Model W-385, sold by Heat Systems- Ultrasonics Corp. of Farmingdale, New York.
• the titration is performed with the sample being stirred constantly.
• a potentiometric titration meter an ESA-8000 System Model MBS-8000, sold by Matec Applied Science, Inc. of Hopkinton, Mass., was employed for the titration.
• a laser light scattering instrument is used to measure sizes of barium sulfate particles.
• the instrument was a Micro-Trac FRA (full range analyzer) , sold by Leeds & Northrup of St. Russia, Fla. Sonically dispersed samples are employed. Each sample consists of 0.8 to 2.0 grams of the particles in 80 ml of deionized water which containes 10 drops of "Darvon C" dispersant, sold by R. T. Vanderbilt Chemical of Norwalk, Conn. At least three samples of each material are analyzed to obtain average particle size and particle size distributions.
• R Surface roughness
• R 1000 (A)/(P) wherein A is the BET surface area in square meters/gram and P is the average pore size in Angstroms.
• the surface area of spandex is determined from nitrogen adsorption measurements in accordance with the method of Baunner, Emmet and Teller (BET) . The measurements are made with a Model 2100 Surface Area and Pore Volume Analyzer sold by Micromeritics Instruments Corp. of Norcross, Georgia. To prepare the test samples, the filaments are conditioned for about 10 hours under a vacuum of about 0.025 mm of mercury while at a temperature of about 120°C. During the testing the instrument automatically measures at least 21 points during each adsorption-desorption cycle. From these data, the BET surface area A, individual pore sizes, and average pore size, P, are calculated. The surface roughness parameter, R, of the spandex is then computed by the formula given above.
• thermogravimetric analyzer To determine the temperatures at which silicone lubricating oil is released from a spandex surface, a thermogravimetric analyzer is employed to raise the temperature of spandex samples at a rate of 10°C per minute, with the sample being flushed by a 100-cc/min flow of nitrogen. The flushed gas is passed to a Fourier Transform Infra-red Analyzer. The time at which the infra-red analyzer detects the presence of silicone oil in the nitrogen gas is correlated with the temperature of the sample when the oil is evolved from the sample.
• Over-end take-off tension a measure of the tackiness of a spandex yarn, is determined in accordance with the procedure disclosed in Hanzel et al, United States Patent 4,296,174, column 4, lines 20-45, with reference to Figure 6 of the patent, which disclosure is hereby incorporated by reference. In accordance with this technique, measurement is made of the average tension required to remove a 183-meter sample of spandex yarn from a supply package of the yarn at a delivery rate of 45.7 meters per minute.
• Strength and elastic properties of the spandex are measured in accordance with the general method of ASTM D 2731-72. Three filaments, a 2-inch (5-cm) gauge length and a zero-to-300% elongation cycle are used for each of the measurements. The samples are cycled five times at an constant elongation rate of 800% per minute and then held at the 300% extension for half a minute after the fifth extension. "Load power” is reported herein in deciNewtons/tex and is the stress measured at a given extension during the first load cycle. "Unload Power” is reported herein in deciNewtons/tex and is the stress measured at a given extension during the fifth unload cycle. Percent elongation at break is measured on the sixth extension cycle.
• Percent set also is measured on samples that have been subjected to five 0-300% elongation-and-relaxation cycles.
• the polymer for the spandex is made from a capped glycol, which was the reaction product of P04G and MDI prepared with a capping ratio (i.e., the molar ratio of MDI to P04G) of 1.63 and having an NCO content of 2.40%.
• the capped glycol is chain extended with a 90/10 diamine mixture of EDA/MPMD.
• DEA is employed as a chain terminator.
• the polymer is dissolved in DMAc to provide a solution having 36.8% solids.
• Additives consisting of 1.5% “Cyanox”-1790 antioxidant, 2% “Methacrol”-2138, and 0.6% silicone oil (based on the weight of the polymer) are added to the solution.
• the solution described in the preceding paragraph is dry spun into 4-coalesced-filament 44-dtex yarns (or 2- filament 22-dtex yarns) in a conventional apparatus.
• the solution is metered through spinneret orifices into a spin shaft, in which the thusly spun solution forms filaments and DMAc solvent evaporates from the filament.
• a co- current flow of nitrogen gas is supplied to the shaft at a temperature of 420°C, which results in a temperature of 220°C at the half-way point through the shaft.
• the DMAc gas exits through a pipe in a side wall near the bottom of the shaft.
• the filaments are false-twisted by jets at the bottom of the shaft to cause groups of filaments to coalesce into single threadlines.
• a counter current flow of nitrogen which is supplied at 135°C near the bottom of the shaft, combines with the exiting DMAc.
• the coalesced multi-filament threadlines exit through the bottom of the shaft.
• a silicone oil finish lubricant is applied to the threadlines by a kiss roll applicator, to provide an add- on of about 3.5% based on the weight of the threadline.
• the yarn is then wound up at a speed of about 840 meters per minute.
• Barium sulfate is added to the polymer solution as follows. An 11.4% solution of polymer in DMAc is made by diluting 450 parts of polymer solution in 1000 parts of DMAc and then adding 1050 parts (by weight) of barium sulfate particles to the dilute solution while providing thorough mixing. The resulting slurry is then passed through a sandgrinder to break up any agglomerates that had possibly formed. The concentration of the barium sulfate in the slurry is 42%. The barium sulfate slurry is then metered to the polymer solution that already contains the other additives at a rate selected to provide a 1.5% concentration of barium sulfate in the polymer
• This example shows the effects of isoelectric point of the barium sulfate additive on the surface roughness of the spandex that is produced. Seven 44-dtex samples are prepared by the above-described procedures.
• Example 1 Two samples (Samples 1 and 2) are in accordance with the invention and five samples (Comparison Samples A, B, C, D and E) are outside the invention. All samples are prepared in the same manner, except as otherwise noted in
• IEP isoelectric point d — average pore size in Angstroms
• S BET surface area, square meters per gram
• R roughness parameter
• Samples 1 and 2 are prepared with Sachtleben Micro-grade blanc fixe. Comparison Sample A is prepared with Sachtleben N-Grade blanc fixe and Comparison Sample B, with Fisher Scientific certified pure barium sulfate. Comparison Samples C, D, and E are prepared with no barium sulfate additive; D is wound up at 640 meters/min and E, at 914 meters/min.
• Samples identical to Sample 3 and Comparison Sample F are prepared except that corresponding Samples 4 and G are 2-filament 22-dtex spandex yarns.
• the over-end take-off tension (OET) is measured for wound up yarns of Sample 4 and Comparison Sample G, immediately after spinning and then after 2 weeks, 4 weeks and 8 weeks of storage. Table III summarizes the results. Table III
• two bobbins of 44-dtex spandex yarns are made by the procedures of Example I, but with 2 weight percent of titanium dioxide dispersed therein, and then tested for over-end take-off tension after 8 weeks of room-temperature storage.
• Sample 6 contains 1.5% of micro-grade barium sulfate and is of the invention.
• Comparison Sample J contains no barium sulfate and is outside the invention.
• the measured OET for Sample 6 of the invention was 0.141 centiNewtons versus 0.380 cN for Comparison for sample J.

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• Textile Engineering (AREA)
• Manufacturing & Machinery (AREA)
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• 1993
  • 1993-06-26 TW TW082105102A patent/TW316931B/zh not_active IP Right Cessation
• 1994
  • 1994-05-25 JP JP50182395A patent/JP3279569B2/ja not_active Expired - Lifetime
  • 1994-05-25 WO PCT/US1994/005713 patent/WO1994029499A1/en active IP Right Grant
  • 1994-05-25 DE DE69412824T patent/DE69412824T2/de not_active Expired - Lifetime
  • 1994-05-25 EP EP94916808A patent/EP0702732B1/en not_active Expired - Lifetime
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