Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
• • 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
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2913—Rod, strand, filament or fiber
  • Y10T428/298—Physical dimension

Definitions

• the disclosure relates generally to a method of producing fibrillated polypyridobisimidazole floe and papers made from such floe.
• Fibrillated fibers have been used in the production of paper. Fibrillation of aramid floe is typically performed in a disk refiner. However, in the standard process, a refiner not only fibrillates the floe but also cuts the floe, reducing the length of the floe and forming what has been call pulp.
• a significant amount of energy is used in producing para-aramid pulp and other pulps from high performance fibers (up to about 8000 kJ/kg) .
• the invention concerns a process for making a fibrillated polypyridobisimidazole floe comprising: providing polypyridobisimidazole filaments having an average cut length of from about 0.5 to 10 mm; and applying energy to the polypyridobisimidazole filaments to produce a fibrillated floe; where the fibrillated floe has essentially the same average cut length after the application of energy as before the application of energy; the fibrillated floe having a Canadian Standard Freeness (CSF) 5 when dispersed in water by itself, of from about 400 to 750 ml.
• CSF Canadian Standard Freeness
• the energy is applied by agitation.
• the polypyridobisimidazole filaments are contacted with a fluid to form a dispersion and the energy is applied to the dispersion containing the polypyridobisimidazole filaments.
• the energy is applied to the dispersion by pumping the dispersion.
• the amount of energy applied to the polypyridobisimidazole filaments to make the fibrillated floe is from 360 to 3600 kJ/kg.
• One preferred fluid is water.
• One polypyridobisimidazole is PIPD.
• the polypyridobisimidazole filaments have an average cut length of from about 1 to 1.5 mm.
• the invention concerns a process for making paper comprising: providing polypyridobisimidazole filaments, said filaments having an average cut length of from about 0.5 to 10 mm; and applying energy to the polypyridobisimidazole filaments to produce a fibrillated floe; the fibrillated floe having essentially the same average cut length after the application of energy as before the application of energy; the fibrillated floe having a Canadian Standard Frccncss (CSF) 5 when dispersed in water by itself, of from about 400 to 750 ml; contacting the fibrillated floe with water to form a dispersion; and removing at least a portion of the water from the dispersion to yield paper.
• CSF Canadian Standard Frccncss
• a portion of the water is removed from the dispersion via a screen or wire belt to produce a wet water and the wet paper is dried.
• the process comprises the additional step of densifying the paper composition by calendering or compression at some point in the process.
• Some processes further comprise a binder material.
• the binder material comprises non granular, fibrous or film-like, meta-aramid fibrids having an average maximum dimension of 0.2 to 1 mm, a ratio of maximum to minimum dimension of 5 : 1 to 10:1, and a thickness of no more than 2 microns.
• the binder material comprises thermoplastic or thermoset resins in the form of suspensions, emulsions, solutions, powders, flakes or fibers.
• the process comprises the additional step of heat treating the paper composition at or above the glass transition temperature of the binder material.
• the heat treatment is either followed by or includes calendering the paper composition.
• the invention also relates to a f ⁇ brillated polypyridobisimidazole floe having cut length of from 0.5 to 10 mm and Canadian Standard Freeness of from about 400 to about 750 ml., when dispersed by itself in water.
• the f ⁇ brillated polypyridobisimidazole floe has a cut length of from about 1 to 1.5 mm.
• the f ⁇ brillated polypyridobisimidazole floe comprises PTPD.
• Figure 1 shows PIPD floe prior to fibrillation.
• Figure 2 shows f ⁇ brillated PIPD floe having the same average length (about 6.4 mm) as it did prior to fibrillation and has many fibrils coming out of the core fiber stalk.
• the invention concerns a process for making a fibrillated polypyridobisimidazole floe comprising: providing polypyridobisimidazole filaments having an average cut length of from about 0.5 to 10 mm; and applying energy to the polypyridobisimidazole filaments to produce a fibrillated floe; where the fibrillated floe has essentially the same average cut length after the application of energy as before the application of energy; the fibrillated floe having a Canadian Standard Freeness (CSF), when dispersed in water by itself, of from about 400 to 750 ml.
• CSF Canadian Standard Freeness
• the practice of this invention results in a true fibrillated floe that has essentially the same average length as the starting floe.
• the amount of energy, which is necessary to apply to the floe to achieve fibrillation is about from 360 to 3600 kJ/kg. . This is below the level of energy used for making para-aramid pulp and pulps from other high performance fibers (up to 8000 kJ/kg).
• the floe of this invention means short lengths of fiber, shorter than staple fiber.
• the length of floe is about 0.5 to about 15 mm and a diameter of 4 to 50 micrometers, preferably having a length of 1 to 12 mm and a diameter of 8 to 40 micrometers.
• Floe that is less than about 1 mm does not add significantly to the strength of the material in which it is used.
• Floe or fiber that is more than about 15 mm often does not function well because the individual fibers may become entangled and cannot be adequately and uniformly distributed throughout the material or slurry.
• Floe is generally made by cutting continuous spun filaments or tows into specific-length pieces using conventional fiber cutting equipment. Generally this cutting is made without significant or any fibrillation of the fiber.
• Paperers are flat sheets producible on a paper machine, such as a Fourdrinier or inclined- wire machine.
• these sheets arc generally thin, fibrous sheets comprised of a network of randomly oriented, short fibers laid down from a water suspension and bonded together by their own chemical attraction, friction, entanglement, binder, or a combination thereof.
• the paper can have basis weight from about 10 to about 700 g/m2 and a thickness from about 0.015 to about 2 mm.
• the floe of this invention has fibrils.
• Fibril means a small fiber having a diameter as small as a fraction of a micrometer to a few micrometers and having a length of from about 10 to 100 micrometers.
• the fibrillated floe of this invention has fibrils generally extending from the main larger floe fiber. Fibrils act as hooks or fasteners to ensnare and capture adjacent material.
• the instant invention utilizes polypyridobisimidazole fiber. This fiber is made from a rigid rod polymer that is of high strength.
• the polypyridobisimidazole polymer of this fiber has an inherent viscosity of at least 20 dl/g or at least 25 dl/g or at least 28 dl/g.
• Such fibers include PIPD fiber (also known as M5® fiber and fiber made from poly[2,6-diimidazo[4,5-b:4,5- e]- pyridinylene— l,4(2,5-dihydroxy)phenylene).
• PIPD fiber is based on the structure:
• Polypyridobisimidazole fiber can be distinguished from the well known commercially available PBI fiber or polybenzimidazole fiber in that that polybenzimidazole fiber is a polybibenzimidazole.
• Polybibenzimidazole fiber is not a rigid rod polymer and has low fiber strength and low tensile modulus when compared to polypyridobisimidazoles.
• PIPD fibers have been reported to have the potential to have an average modulus of about 310 GPa (2100 grarns/denier) and an average tenacity of up to about 5.8 Gpa (39.6 grams/denier). These fibers have been described by Brew, et al., Composites Science and Technology 1999, 59, 1109; Van der Jagt and Beukers, Polymer 1999, 40, 1035; Sikkema, Polymer 1998, 39, 5981; Klop and Lammers, Polymer, 1998, 39, 5987; Hageman, et al., Polymer 1999, 40, 1313.
• Polypyridoimidazole polymer may be made by reacting a mix of dry ingredients with a poryphosphoric acid (PPA) solution.
• the dry ingredients may comprise pyridobisimidazole-forming monomers and metal powders.
• the polypyridobisimidazole polymer used to make the rigid rod fibers used in the fabrics of this invention should have at least 25 and preferably at least 100 repetitive units.
• the relative molecular weights of the polypyridobisimidazole polymers are suitably characterized by diluting the polymer products with a suitable solvent, such as methane sulfonic acid, to a polymer concentration of 0.05 g/dl, and measuring one or more dilute solution viscosity values at 30°C.
• Molecular weight development of polypyridobisimidazole polymers of the present invention is suitably monitored by, and correlated to, one or more dilute solution viscosity measurements.
• V rel or " ⁇ iel “ or “n lel ”
• Vi nh or “ ⁇ i nh “ °r “n ⁇ ”
• Vint is expressed in units of inverse concentration, typically as deciliters per gram (“dl/g”).
• the polypyridobisimidazole polymers are produced that are characterized as providing a polymer solution having an inherent viscosity of at least about 20 dl/g at 30 0 C at a polymer concentration of 0.05 g/dl in methane sulfonic acid. Because the higher molecular weight polymers that result from the invention disclosed herein give rise to viscous polymer solutions, a concentration of about 0.05 g/dl polymer in methane sulfonic acid is useful for measuring inherent viscosities in a reasonable amount of time.
• Exemplary pyridobisimidazole-forming monomers useful in this invention include 2,3,5,6-tetraaminopyridine and a variety of acids, including terephthalic acid, bis-(4- benzoic acid), oxy-bis-(4-benzoic acid), 2,5-dihydroxyterephthalic acid, isophthalic acid, 2,5- pyridodicarboxylic acid, 2,6-napthalenedicarboxylic acid, 2,6-quinolinedicarboxylic acid, or any combination thereof .
• the pyridobisimidazole forming monomers include 2,3,5,6- tetraaminopyridine and 2,5-dihydroxyterephthalic acid.
• the pyridoimidazole-forming monomers are phosphorylated.
• phosphorylated pyridoimidazole-forming monomers are polymerized in the presence of polyphosphoric acid and a metal catalyst.
• Metal powders can be employed to help build the molecular weight of the final polymer.
• the metal powders typically include iron powder, tin powder, vanadium powder, chromium powder, and any combination thereof.
• the pyridobisimidazole-forming monomers and metal powders are mixed and then the mixture is reacted with polyphosphoric acid to form a polypyridoimidazole polymer solution. Additional polyphosphoric acid can be added to the polymer solution if desired.
• the polymer solution is typically extruded or spun through a die or spinneret to prepare or spin the filament.
• the f ⁇ brillated floe of this invention is made by applying energy to the polypyridobisimidazole filaments to produce a f ⁇ brillated floe; where the f ⁇ brillated floe has essentially the same average cut length after the application of energy as before the application of energy.
• the energy is applied by agitation, such as by an impeller or a rotor in a mixer or other mixing vessel.
• the polypyridobisimidazole filaments are contacted with a fluid to form a dispersion and the energy is applied to the dispersion containing the polypyridobisimidazole filaments.
• the energy is applied to the dispersion by pumping the dispersion. Any suitable method that imparts energy that forces the floe pieces to come in contact repeatedly with other floe pieces or with a solid surfaces without cutting the floe may be used in the process of this invention. In a preferred embodiment the amount of energy or shear is applied to the outer surface of the floe in an about 360 to 3600 kJ/kg of floe.
• Canadian Standard Freeness TCSF is a well-known papermakers' measure of the facility for water to drain through a calibrated screen from a slurry or dispersion of pulp or fibers. Freeness is measured by TAPPI test T227. It mimics what happens as a fiber/particle/water slurry forms paper on the moving screen of a paper machine. Data obtained from conduct of that test are expressed as Canadian Standard Freeness Numbers, which are the milliliters of water that drain from an aqueous slurry under specified conditions. A large number, i.e., a high freeness, indicates that water drains rapidly through the fiber pad accumulating on the screen. A low number indicates that the fiber slurry drains slowly.
• Example 2 Another 1.6 grams of PIPD fioc was flbrillated exactly in the same way as in Example 1. The fibrillated fioc from Example 1 and this Example were then combined to make an adequate fioc sample, and the Canadian Standard Freeness (CSF) was measured. A CSF of 650 ml was determined for the accumulative sample.
• CSF Canadian Standard Freeness

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• 2006
  • 2006-12-19 US US12/084,006 patent/US7686920B2/en not_active Expired - Fee Related
  • 2006-12-19 EP EP06846674A patent/EP1963571B1/en not_active Ceased
  • 2006-12-19 KR KR1020087017560A patent/KR101359868B1/ko not_active Expired - Fee Related
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  • 2006-12-19 CN CN200680047820XA patent/CN101341295B/zh not_active Expired - Fee Related
  • 2006-12-19 WO PCT/US2006/062284 patent/WO2007076343A2/en not_active Ceased

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