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
  • 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
  • D21H13/26—Polyamides; Polyimides

Definitions

• the invention relates to a paper comprising at least one of a fiber, pulp, fibril, floc, and fibrid containing a polybenzazole structure or a polybenzazole precursor structure. the invention further pertains to a method for making such papers and to the use thereof.
• fiber, pulp, fibril, or fibrid having superior properties, including mechanical properties can be obtained by a process in which an optical anisotropic dope, containing a high concentration of a high molecular weight aromatic polyamide having a substituent such as a hydroxy, thiohydroxy, or amine group in an acidic solvent, is applied using a wet air gap spinning process, a jet spinning process, or any other conventional method to obtain a fiber, pulp, fibril, or fibrid, which are then heat treated.
• an optical anisotropic dope containing a high concentration of a high molecular weight aromatic polyamide having a substituent such as a hydroxy, thiohydroxy, or amine group in an acidic solvent
• the present invention relates to paper made from at least one of a fiber, pulp, fibril, floc, and fibrid comprising polybenzazole having a repeating unit of formula (I) and/or (II) wherein Ar 1 and Ar 2 are independently an aromatic group having 4 to 12 carbon atoms, Ar 1 and Ar 2 have the para or meta configuration, and X and Y are the same or different and selected from O, S, and NH; and wherein the paper contains less than 0.15 wt% of non-extractable phosphorus compound.
• para and metal relate to the positions of the two amino groups or the two carbonyl groups at the aromatic ring. If Ar 2 contains more than one aromatic ring there are formally no para and meta positions, but the corresponding positions are mentioned pseudo-para and pseudo-meta positions, which are included in the definition of "para” and"meta”.
• the present fibers, pulp, fibrils, floc, or fibrids are manufactured by a method comprising the steps of spinning or extruding a dope and solidifying it to a coagulation liquid, and then subjecting the obtained fiber as was described in EP 07008742 .
• the invention also relates to a precursor paper, which as such has excellent properties and therefore can be used as such.
• This precursor paper contains a polybenzazole precursor having the repeating unit expressed by formula (III): wherein Ar 1 and Ar 2 are independently an aromatic group having 4 to 12 carbon atoms, Ar 1 and Ar 2 have the para or meta configuration, X and Y are the same or different and selected from O, S, and NH, and n is 0 or 1.
• Ar 1 examples are phenylene, naphthalenediyl, and bivalent heteroaromatic groups. Ar 1 may be substituted with hydroxy and/or halogen groups.
• Ar 1 is preferably selected from and
• Ar 2 is a tri- or quadrivalent aromatic group with 4-12 carbon atoms.
• a 2 examples of A 2 are benzenetri- or tetrayl, naphthalenetri- or tetrayl, diphenyltri- or tetrayl, and tri- or quadrivalent heterocyclic group can be listed as Ar 2 .
• Ar 2 moieties may be substituted with a hydroxy and/or halogen group.
• Ar 2 is preferably selected from:
• the benzene group is the most preferred Ar 2 group.
• Ar 1 is para- or meta-phenylene: or and Ar 2 is or wherein X and Y are O, and the straight lines represent a bond.
• the fiber may also be a copolymer containing repeating units expressed by formula (IV)
• the Ar 1 groups have independently the previously given meanings.
• the preferred Ar 1 is para-or meta-phenylene.
• the polybenzazole preferably comprises 40 to 100 mole% of the repeating unit expressed by formula (I) and/or (II) with 60 to 0 mole% of the repeating unit expressed by formula (IV), to a total of 100 mole%.
• the polybenzazole preferably comprises 60 to 100 mole% of the repeating unit expressed by formula (I) and/or (II) with 40 to 0 mole% of the repeating unit expressed by formula (IV), to a total of 100 mole%.
• the polybenzazole which can be obtained form the polymer precursors contains imidazole, thiazole, and/or oxazole rings.
• polybenzazole precursor containing one of the following repeating units is especially preferred. or or or or or or
• PBO paper is known in the art, i.e. as mentioned in patent US 6890636 , such paper inherently contains substantial amounts of phosphoric acid which was used as spin dope for making fiber, and which cannot completely be removed.
• the PBO paper of this invention contains less than 0.15 wt% of non-extractable phosphorus compound (i.e. mainly phosphoric acid), preferably much less such as less than 30 ppm, and most preferably none or virtually none of phosphorus compound (when the spin dope does not contain any phosphoric acid).
• the unique method for making the PBO paper of this invention resides in a method wherein the ring-closed PBO structure is obtained from an open precursor structure still having OH, SH, or NH 2 groups. These hydrophilic groups allow the precursor to dissolve in hydrophilic solvents such as water, alcohol, water-alcohol mixtures, and the like.
• PBO paper having less than 0.15 wt% phosphorus compound is unknown.
• the known PBO papers have been made from PBO-polyphosphorus acid-containing spin dopes, leading to paper having (much) more than 0.15 wt% non-extractable phosphorus.
• small amounts of phosphorus acid or other phosphorus compounds can be added to the spin dope, leading to papers having minor amounts (i.e. less than 0.15 wt%) of phosphorus.
• the amount of phosphorus present in the paper can easily be measured by using standard methods such as by spectroscopy or titration.
• the papers of this invention may include combinations of fiber, pulp, fibril, floc or fibrid, such as fibrids and floc.
• the papers of the invention can be made by conventional papermaking processes, which processes allow adding common additives and auxiliary materials to the material for making paper, such as pigments, binders, silicates, fillers, and other additives.
• the paper such obtained may be processed further such as by applying known calendaring methods to further enhance the density of the paper.
• fibrids refers to non-granular film-like particles.
• the fibrids have an average length of 0.2 to 1 mm with a length-to-width aspect ratio of 5:1 to 10:1.
• the thickness dimension is on the order of a fraction of a micron.
• Such fibrids when fresh, are used wet and are deposited as a binder physically entwined about the floc component of the paper. Fresh fibrids and previously-dried fibrids can be used in paper of this invention.
• the term "floc" refers to short fibers, typically having a length of 2 to 12 mm and a linear density of 1-10 decitex.
• the floc can be fresh or it can be previously-dried. If fresh, it has not before been used in any product.
• Paper pulp may comprise floc and fibrids, generally, in amounts of about 50-60%, by weight, fibrids and 40-50%, by weight, floc. Even after comminution and milling, the floc in aramid paper pulp is bound, to some extent, by the fibrids.
• the fibrids being in a dried state, are bound together or collapsed and less useful as binder material than the fresh, never-dried, fibrids; but, due to their random, rigid, irregular, shape, contribute an increased porosity to the final paper structure.
• those fibrid and floc components taken from dried papers may be called previously-dried fibrids and previously-dried floc.
• Dried paper sheets containing polybenzazole precursor can also be processed through a high speed milling machine, such as a turbulent air grinding mill known as a Turbomill or an Ultra-Rotor, and then wet refined.
• Turbulent air grinding mills are preferred for comminuting papers which have been calendered; but the grinding mills result in slightly shortened fiber lengths. Paper of this invention using paper pulp with shortened fiber lengths exhibits slightly reduced wet strength and a tendency to worsen paper machine continuity.
• the paper made from the polybenzazole precursor material can be used as such. It has excellent properties as will further be demonstrated in the experimental part. However, the properties of this paper can easily be changed or improved by functionalizing at least part of the free XH and YH groups, such as OH groups. These free groups are able to react with monomers and polymers having reactive groups, such as esters, isocyanates, epoxides, and other functionalizing agents to give a covalent bond between X and/or Y and the functionalizing agent. If part of the free XH and YH groups is functionalized these papers can also be heat treated to convert the polymer precursor by a cyclizing process to ring-closed PBO polymers, thereby obtaining functionalized PBO paper.
• the PBO obtained can also be free of phosphorus compounds. It is a further advantage that it is no longer required to make the paper from almost insoluble PBO polymers, but the papermaking process can be performed with readily soluble polymer precursors, and conversion to PBO takes place after formation of the paper.
• the papers from this invention exhibit lower porosity than PPTA papers making them very suitable for electrical applications such as in electrical insulation material.
• the papers are further suitable for application in honeycomb structures and in constructive materials.
• the papers of the present invention both for PBO precursor-containing papers and PBO papers, have a much higher strength than known papers, as shown by EAB (elongation at break) and TI (tenacity index) data.
• EAB elongation at break
• TI tenacity index
• the present papers are superior to PPTA paper and even to Nomex®, which is considered the strongest paper known until now.
• the extreme strength of the present papers makes it possible to produce extreme thin papers.
• the papers of this invention also have superior heat stability compared to PPTA paper and Nomex®.
• the first sample had a polymer concentration of 7.4%
• the second sample (after dilution with NMP) had a concentration of 5%
• the final product had a polymer concentration of 4%.
• the relative viscosity of the reaction product was 3.43.
• the polymerization procedure for the second batch was similar, except that after 60 minutes a sample was taken and 4.0 L of NMP were added. The mixture was stirred for 30 min and then emptied. By applying this procedure, the first sample had a polymer concentration of 7.4% and the final product had a polymer concentration of 4%. The relative viscosity of the reaction product was 3.06.
• the polymerization batches were mixed prior to spinning.
• Polymerization of PPTA para-phenyleneterephthalamide was carried out using a 160 L Drais reactor. After sufficiently drying the reactor, 64 L of NMP/CaCl 2 with a CaCl 2 concentration of 2.5 wt% were added to the reactor. Subsequently, 1522 g of PPD were added and dissolved at room temperature. Thereafter the PPD solution was cooled to 5 °C and 2824 g of TDC were added. After addition of the TDC the polymerization reaction was continued for 45 min. Then the polymer solution was neutralized with a calcium oxide/NMP-slurry (780 g of CaO in NMP). After addition of the CaO-slurry the polymer solution was stirred for another 30 min.
• This neutralization was carried out to remove the hydrochloric acid (HCl), which is formed during polymerization.
• a gel-like polymer solution was obtained with a PPTA content of 4.5 wt% and having a relative viscosity of 3.0 (in 0.25% H 2 SO 4 ).
• This product has an etarel ( ⁇ rel ) of 2.4 and a polymer concentration of 3.6% and was used to spin fibrids as well as pulp. Water was used as coagulant.
• Example 1 and Comparative Example 1 were spun through a jet spinning nozzle (spinning hole 500 ⁇ m) at 20 Uh. Water was added through a ring-shaped channel flowing perpendicular to the polymer flow. During spinning the polymer flow was kept constant while the coagulant pressure was changed for the different samples in order to vary the SR (°SR) of the product.
• SR °SR
• Example 1 and Comparative Example 1 were spun into pulp through a 1 hole jet spinning nozzle (spinning hole 350 ⁇ m). The solution was spun into a zone of lower pressure. An air jet was separately applied perpendicularly to the polymer stream through ring-shaped channels to the same zone were expansion of air occurred. Thereafter, the pulp was coagulated with water in the same zone by means of applying a coagulant jet through ring-shaped channels under an angle in the direction of the polymer stream.
• Table 2 Properties of paper samples from fibrid Paper Grammage Calliper Density EAB TI Sample (g/m 2 ) (mm) (g/cm 3 ) (%) (Nm/g) B1 99 0.168 0.59 4.3 85.2 B2 50 0.115 0.44 3.6 75.3 B3 29 0.073 0.39 3.7 72 B4 16 0.058 0.28 2.5 41.6 D1 110 0.284 0.39 1.7 28.3 D2 52 0.193 0.27 1.7 19 D3 31 0.131 0.23 1.1 14.1 D4 16 0.092 0.17 1.6 8.1
• TGA experiments were carried out by means of a Setaram TGA/DSC 111, under nitrogen gas.
• the paper samples were first cut into pieces and then put in Platinum (open) cells.
• the sample weight that was used was between 10 and 20 mg.
• the samples were heated from 20 °C to 700 °C.
• the decomposition temperature Td 5% is the temperature at which 5% weight loss based on TGA thermogram is obtained under these conditions.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)
• Artificial Filaments (AREA)
• Organic Insulating Materials (AREA)

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• 2007
  • 2007-09-12 EP EP07017825A patent/EP2037039A1/fr not_active Withdrawn
• 2008
  • 2008-09-02 US US12/674,819 patent/US20110083820A1/en not_active Abandoned
  • 2008-09-02 JP JP2010524454A patent/JP2010539341A/ja not_active Withdrawn
  • 2008-09-02 WO PCT/EP2008/061554 patent/WO2009033983A1/fr not_active Ceased
  • 2008-09-02 EP EP08803525A patent/EP2191067B1/fr not_active Not-in-force
  • 2008-09-02 CN CN200880106946A patent/CN101802302A/zh active Pending

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