Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/08—Melt spinning methods
• • 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
  • D01F6/74—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polycondensates of cyclic compounds, e.g. polyimides, polybenzimidazoles
• • 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
  • D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D01F6/34—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising unsaturated alcohols, acetals or ketals as the major constituent

Definitions

• the present invention relates to improved processes for spinning fibers that contain polybenzoxazole (“PBO”) or polybenzothiazole (“PBT”) polymer.
• PBO polybenzoxazole
• PBT polybenzothiazole
• Lyotropic liquid-crystalline polybenzoxazole and polybenzothiazole are not thermoplastic. They are typically made into fibers by dry-jet, wet-spinning techniques, in which a dope that contains the polybenzazole polymer and an acid solvent is spun through a spinneret, drawn across an air gap, and coagulated by contact with a fluid that dilutes the solvent and is a non-solvent for the polymer. The individual filaments formed by this process can be combined to form one or more fibers of varying diameter.
• the first aspect of the present invention is a process to spin a fiber made-up of more than one filament from a liquid-crystalline dope that contains a solvent and a
• polybenzazole polymer which is polybenzoxazole, polybenzothiazole or a copolymer thereof, said process comprising the steps of:
• a second aspect of this invention is a polybenzazole fiber with an average fiber diameter of no more than about 18 ⁇ m obtained through the process of the first aspect of the present invention.
• the present invention uses dopes that contain a polybenzazole polymer, which is polybenzoxazole, polybenzothiazole or a copolymer of those polymers.
• PBO, PBT and random, sequential and block copolymers of PBO and PBT are described in references such as Wolfe et al. , Liquid Crystalline Polymer Compositions, Process and Products, U. S. Patent 4,703,103 (October 27, 1987); Wolfe et al . , Liquid Crystalline Polymer Compositions, Process and Products, U. S. Patent 4,533,692 (August 6, 1985); Wolfe et al. , Liquid Crystalline Poly(2,6-Benzo-thiazole) Compositions, Process and Products, U. S.
• Patent 4,533,724 (August 6, 1985), Wolfe, Liquid Crystalline Polymer Compositions, Process and Products, U. S. Patent 4,533,693 (August 6, 1985), Evers, Thermooxidatively Stable Articulated p-Benzobisoxazoie and p-3enzobisthiazole Polymers, U. S. Patent 4,359,567 (November 16, 1982), Tsai et al. , Method for Making
• the polymer may contain AB-mer units, as represented in Formula 1 (a), and/or AA/BB-mer units, as represented in Formula 1 (b)
• Each Ar represents an aromatic group selected such that the polybenzazole polymer is a lyotropic liquid-crystalline polymer (that is, it forms liquid-crystalline domains when its concentration in solution exceeds a "critical concentration point").
• the aromatic group may be heterocyclic, such as a pyridinylene group, but it is preferably carbocyclic.
• the aromatic group may be a fused or unfused polycyclic system, but is preferably a single six-membered ring. Size is not critical, but the aromatic group preferably contains no more than about 18 carbon atoms, more preferably no more than about 12 carbon atoms and most preferably no more than about 6 carbon atoms.
• Ar 1 in AA/BB-mer units is preferably a 1 ,2,4,5-
• Ar in AB-mer units is preferably a 1 ,3,4-phenylene moiety or an analog thereof.
• Each Z is independently an oxygen or a sulfur atom.
• Each DM is independently a bond or a divalent organic moiety selected such that the polybenzazole polymer is a lyotropic liquid crystalline polymer.
• the divalent organic moiety is preferably an aromatic group (Ar) as previously described. It is most preferably a 1 ,4-phenylene moiety or an analog thereof.
• each azole ring is bonded to adjacent carbon atoms in the aromatic group, such that a five-membered azole ring fused with the aromatic group is formed.
• the azole rings in AA/BB-mer units may be in cis- or trans-position with respect to each other, as illustrated in 1 1 Ency. Poly. Sci. & Eng., supra at 602.
• the polymer preferably consists essentially of either AB-PBZ mer units or AA/BB- -PBZ mer units, and more preferably consists essentially of AA/BB-PBZ mer units.
• Preferred mer units are illustrated in Formulae 2(a)-(h).
• the polymer more preferably consists essentially of mer units selected from those illustrated in 2(a)-(h), and most preferably consists essentially of a number of identical units selected from those illustrated in 2(a)-(d).
• Each polymer preferably contains on average at least about 25 repeating units, more preferably at least about 50 repeating units and most preferably at least about 100 repeating units.
• the intrinsic viscosity of rigid AA/BB-PBZ polymers in methanesulfonic acid at 25°C is preferably at least about 10 dL/g, more preferably at least about 15 dL/g and most preferably at least about 20 dL/g. For some purposes, an intrinsic viscosity of higher than 25 dL/g or 30 dL/g may be best. Intrinsic viscosities of 60 dL/g are possible.
• the intrinsic viscosity of semi-rigid AB-PBZ polymers is preferably at least about 5 dL/g, more preferably at least about 10 dL/g and most preferably at least about 15 dL/g.
• the polymer or copolymer is dissolved in a solvent to form a solution or dope.
• a solvent is preferably an acid capable of dissolving the polymer.
• the acid is preferably non-oxidizing.
• suitable acids include polyphosphoric acid, methanesulfonic acid and sulfuric acid and mixtures of those acids.
• the acid is preferably polyphosphoric acid and/or methanesulfonic acid, and is more preferably polyphosphoric acid.
• the dope should contain a high enough concentration of polymer for the dope to contain liquid crystalline domains.
• concentration of the polymer is preferably at least about 7 weight percent, more preferably at least about 10 weight percent and most preferably at least about 14 weight percent.
• the maximum concentration is limited primarily by practical factors, such as polymer solubility and dope viscosity.
• concentration of polymer is seldom more than 30 weight percent, and usually no more than about 20 weight percent.
• Suitable polymers or copolymers and dopes can be synthesized by known procedures, such as those described in Wolfe et al ., U. S. Patent 4,533,693 (August 6, 1985), Sybert et al. , U. S. Patent 4,772,678 (September 20, 1988), Harris, U. S. Patent 4,847,350 (July 1 1 , 1989); Gregory, U. S. Patent 5,089,591 (February 18, 1992); and Ledbetter et al . , "An Integrated Laboratory Process for Preparing Rigid Rod Fibers from the Monomers," The Materials Science and Engineering of Rigid-Rod Polymers at pp. 253-64 (Materials Res. Soc . 1989).
• suitable monomers (AA-monomers and BB-monomers or AB-monomers) are reacted in a solution of nonoxidizing and dehydrating acid unoer nonoxidizmg atmosphere with vigorous mixing and high shear at a temperature that is increased in step-wise or ramped fashion from no more than about 120°C to at least about 190°C.
• suitable monomers AA-monomers and BB-monomers or AB-monomers
• AA-monomers include terephthalic acid and analogs thereof.
• suitable BB- -monomers include 4,6-diaminoresorcinol, 2,5-diaminohydroquinone, 2,5-diamino-1 ,4- -dithiobenzene and analogs thereof, typically stored as acid salts.
• suitable BB- -monomers include 4,6-diaminoresorcinol, 2,5-diaminohydroquinone, 2,5-diamino-1 ,4- -dithiobenzene and analogs thereof, typically stored as acid salts. Examples of suitable
• AB-monomers include 3-amino-4-hydroxybenzoic acid, 3-hydroxy-4-aminobenzoic acid, 3-amino-4-thiobenzoic acid, 3-thio-4-aminobenzoic acid and analogs thereof, typically stored as acid salts.
• the dope should preferably be very homogeneous and free of gas bubbles and solid particulates. This can be accomplished, but by no means is limited to, by implementation of shear-filtration media (extensive known shear- -filtration media includes the use of silica sand, metal filings and particulates, glass beads, sintered ceramics, sintered porous metal plates and shaped structures and metal screens) . Additional known homogenizing equipments includes single- and multiple-screw extruders, static mixers and other mixing devices.
• the dope is spun from a spinneret that contains a plurality of orifices.
• the density of orifices in the spinneret should be at least about 1 .0 per cm 2 preferably at least about 2.0 per cm 2 , and more preferably at least about 3.0 per cm 2 .
• Each orifice may be of any size desired, but the average diameter at the point where the dope leaves the spinneret is preferably no more than about 0.5 mm, more preferably no more than about 0.4 mm, and most preferably no more than about .35 mm .
• the orifices may be in any desired arrangement, but it is convenient to use a circular or lattice shaped arrangement.
• the dope is spun through the spinneret at a temperature greater thar 100°C.
• the temperature is preferably at least about 120°C and more preferaoly at least about 140°C.
• the maximum temperature is limited by the stability of the dope. It is preferably no more than about 220°C and more preferably no more than about 200°C.
• the optimum rate at which dope passes through the spinneret varies depending upon the spinneret, the dope and the conditions in which they are used.
• Dope filaments exiting the spinneret enter a gap between the spinneret and the coagulation zone where the dope can be drawn.
• the gap is typically called an "air gap” although it need not contain air.
• the gap may contain any gas that does not induce coagulation or react adversely with the dope, such as air, nitrogen, argon, helium or carbon dioxide.
• the spin-draw ratio is the ratio of the take-up velocity of the fiber divioed by the extrusion velocity of the dope.
• the dope filaments are drawn to a spin-draw ratio that is at least about 10, preferably at least about 20, highly preferably at least about 40, more highly preferably at least about 50 and most highly preferably at least about 63
• the length of the air gap is usually at least about 5 cm and at most about 100 cm, although longer and shorter air gaps may be used.
• the gas in the air gap is at a temperature of at least 50°C and at most 100°C.
• the temperature is more preferably between about 60°C and about 90°C.
• the gas serves to cool the filaments before they are contacted with a washing fluid If the temperature is less than 50°C, the filaments cool too fast. When the filaments cool too fast it has been observed that the spinning stress increases rapidly and spinning becomes unstable. This is believed to be the result of the high activation energy of extensional (elongational) flow. If the temperature is more than 100°C, resonance-like spinning instability is believed to occur.
• the cooling gas in the air gap flows at a rate sufficient to uniformly reduce the temperature of the dope filaments, so that the filaments all experience about the same cooling profile.
• the rate of gas flow is between about 0. 02 m/sec and 0.1 m/sec. , more preferably between .05 m/sec and 0.08 m/sec and most preferably between .075 m/sec and 0.08 m/sec.
• the gas flow is preferably perpendicular to the direction in which the filaments move through the air gap.
• the dope filament After the dope filament has been drawn, it is contacted with a fluid that dilutes the solvent and is a non-solvent for the polybenzazole polymer.
• the process of separating the solvent from the polymer is usually referred to as coagulation in the beginning and later, as most of the solvent is removed, as washing.
• the fluid may be a gas, such as steam, but it is preferably a liquid and more preferably an aqueous liquid.
• the fiber may be contacted with fluid in a bath or spray form.
• the bath may be in many different forms, such as the baths described in Japan Laid Open Patent No . 63-12710, Japan Laid Open Patent No. 51 -35716, or Japan Published Patent No. 44-22204.
• the fiber is preferably washed until the residual solvent is reduced to less than about 2. 0 percent, more preferably less than 0. 5 percent and most preferably less than about 0 .1 percent.
• the filaments produced by this process are typically combined into one or more fibers of varying thickness. This combination step usually takes place during the process of making the filament at the stage before, during or after the coagulation/washing of the filament. Fibers made-up of one filament are referred to as monofilament fibers and fibers made-up of more than one filament are referred to as multi-filament fibers.
• a fiber tow is "a large strand of continuous manufactured fiber filaments without definite twist, collected in loose, rope-like form, usually held together by crimp. "(Dictionary of Fiber & Textile
• the coagulated and washed fiber may be collected and dried by known methods. It may be heat treated to increase tensile modulus if desired. A finish may also be applied if desired.
• Fibers may be produced by the process at high speed .
• the speed (measured after the coagulation/ washing step) at which fiber is produced is preferably at least about
• the resulting fiber preferably has an average diameter of no more than about 21 ⁇ m (.83 mils), more preferably no more than about 19 ⁇ m ( .75 mils) and most preferably no more than about 15 ⁇ m ( .59 mils)
• Its denier (“denier” is the weight in grams of 9000 meters of any fiber) is preferably no more than about 5 dpf ("denier-per-filament") and more preferably no more than about 4 dpf.
• the minimum filament diameter and denier are limited by practical considerations. Each individual filament usually has an average diameter of about 8 ⁇ m (.32 mils) and an average denier of at least about. 70 dpf.
• the average tensile strength of the fiber is preferably at least about 200 ksi (1.38 GPa), more preferably at least about 400 ksi (2 .76 GPa), more highly preferably at least about 600 ksi (4. 14 GPa), and most preferably at least about 800 ksi (5.48 GPa).
• the tensile modulus of the heat-treated fiber is preferably at least 35 msi (241 GPa) and more preferably at least 42 msi (290 GPa).
• the tensile modulus of non-heat-treated fiber is usually less than (about half of) the tensile modulus of heat-treated fiber.
• the present invention improves the stability in the simultaneously spinning of a large number of closely space filaments It makes it possible to effectively spin while minimizing line breaks. It has the additional benefits of reducing denier variation between different filaments. Examples

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Artificial Filaments (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)

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• 1992
  • 1992-12-03 US US07/985,078 patent/US5294390A/en not_active Expired - Fee Related
• 1993
  • 1993-11-23 MX MX9307335A patent/MX9307335A/es unknown
  • 1993-11-24 IL IL10773493A patent/IL107734A0/xx unknown
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  • 1993-11-30 WO PCT/US1993/011590 patent/WO1994012702A1/en active Application Filing
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• 1994
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