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WO2025168379A1 - Poudres de polyimide solubles dans un solvant et leur procédé de fabrication - Google Patents

Poudres de polyimide solubles dans un solvant et leur procédé de fabrication

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Publication number
WO2025168379A1
WO2025168379A1 PCT/EP2025/052054 EP2025052054W WO2025168379A1 WO 2025168379 A1 WO2025168379 A1 WO 2025168379A1 EP 2025052054 W EP2025052054 W EP 2025052054W WO 2025168379 A1 WO2025168379 A1 WO 2025168379A1
Authority
WO
WIPO (PCT)
Prior art keywords
particles
polyimide
preferred
polyamic acid
toluenediyl
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2025/052054
Other languages
English (en)
Inventor
Christian Maurer
Jürgen GÖTZENEDER
Vikram DEVARAJAN
William F. Herrmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Evonik Fibres GmbH
Original Assignee
Evonik Fibres GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Evonik Fibres GmbH filed Critical Evonik Fibres GmbH
Publication of WO2025168379A1 publication Critical patent/WO2025168379A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

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
    • D01D5/04—Dry spinning methods
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C08G73/1042—Copolyimides derived from at least two different tetracarboxylic compounds or two different diamino compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C08G73/1067—Wholly aromatic polyimides, i.e. having both tetracarboxylic and diamino moieties aromatically bound
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C08J3/14—Powdering or granulating by precipitation from solutions
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L79/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen or carbon only, not provided for in groups C08L61/00 - C08L77/00
    • C08L79/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08L79/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • 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
    • D01D1/00—Treatment of filament-forming or like material
    • D01D1/02—Preparation of spinning solutions
    • 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
    • D01D5/0007—Electro-spinning
    • D01D5/0015—Electro-spinning characterised by the initial state of the material
    • D01D5/003—Electro-spinning characterised by the initial state of the material the material being a polymer solution or dispersion
    • D01D5/0038—Electro-spinning characterised by the initial state of the material the material being a polymer solution or dispersion the fibre formed by solvent evaporation, i.e. dry electro-spinning
    • 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

Definitions

  • Solvent soluble polyimide powders and a method for making them
  • the invention is directed at solvent soluble polyimide powders with improved properties, in particular good solubility, good processability and transportability with lower safety efforts, good mechanical properties and high molecular weight, and an efficient method for making these powders.
  • US 3,708,458 discloses the preparation of a solvent soluble polyimide by reacting 3,3’,4,4’-benzophenonetetracarboxylic acid dianhydride and a mixture of 4,4’-methylenebis(phenyl diisocyanate) and 2,4- and 2,6-toluene diisocyanate in dimethylformamide, and precipitation of the polymer by introducing the polyimide solution into a polar solvent and drying of the precipitated polymer.
  • Polyimide powders prepared by precipitation in water as described before are commercially available from Ensinger Sintimid GmbH under the trade name P84®. These powders are used for coating components of electrical and electronic devices by processes, where the powder is redissolved in a dipolar aprotic solvent and the component is coated with the resulting polymer solution.
  • the powders are also used for making polyimide shaped bodies by a hot compression molding process with compression and sintering of the powder.
  • the precipitation and grinding process is simple but leads to a significant loss of molecular weight of the polyimide.
  • the polymers require high safety efforts during transport and processing.
  • EP 3 375 609 A1 discloses resin powders with pillar-like shape for additive manufacturing by a powder bed fusion process and a method for preparing these powders by melt spinning of a thermoplastic resin and cutting of the spun fibres. The obtained particles after cutting are subjected to a spheroidizing treatment, including a melting process of the thermoplastic polymer, to round edges of the powder.
  • polyimide as an example of a suitable thermoplastic resin.
  • aromatic polyimides such as the P84® polyimide, have high glass transition temperatures and cannot be processed by melt spinning.
  • the process of EP 3 375 609 A1 is complex and cost intensive.
  • US 3,985,934 and US 4,801 ,502 disclose the preparation of aromatic polyimide fibres by wet spinning or dry spinning of a solution of the polyimide in a dipolar aprotic solvent. The resulting fibres are used for hot gas filtration and producing heat protective clothing. Bag filters comprising needle felts of P84® fibres prepared by dry spinning are commonly used for hot gas filtration in cement production and in power plants.
  • Polyimide(s) as well as “polyamic acid(s)” means, unless stated otherwise, aromatic polyimides respectively aromatic polyamic acids.
  • the present invention relates to a method for making a solvent soluble polyimide powder, comprising the steps a) Providing a solution of a solvent soluble aromatic polyimide or aromatic polyamic acid, in an aprotic dipolar solvent, preferably selected from the group consisting of DMF, NMP, GBL, NEP, DMSO, DMAc, DMPr, 3-methoxy-N,N-dimethylpropionamide and mixtures thereof respectively solvent mixtures comprising one or more of said solvents, b) Spinning of a polymer fibre from the solution of the aromatic polyimide or the aromatic polyamic acid provided in step a) c)
  • an aromatic polyamic acid solution is provided in step a) and used for spinning in step b), obtaining fibre(s) of the aromatic polyimide by imidation of the aromatic polyamic acid fibre(s) obtained in step b), and is characterized in that it comprises a step d) Preparation of a polyimide powder by d1) cutting the fibre(
  • the process of the invention preferably comprises one or more washing steps f), one or more solvent exchange steps g) and one or more drying steps h), wherein the one or more washing steps f) are selected from the group consisting of f1 ) washing the polymer fibre f2) washing the polyimide particles f3) washing the polyamic acid particles, and the one or more solvent exchange steps g) are selected from the group consisting of g 1 ) solvent exchange of the polymer fibre g2) solvent exchange of the polyimide particles g3) solvent exchange of the polyamic acid particles and the one or more drying steps h) are selected from the group consisting of hi) drying the polymer fibre h2) drying the polyimide particles h3) drying the polyamic acid particles and wherein step f1 ), if comprised, is carried out after step b) or c) or g) or g) + h) , step f2) , if comprised, is carried out after step d1) or e) or g) or g) and
  • the residual content of the aprotic dipolar solvent of the fibres and/or particles is reduced to below 5% by weight, preferably below 3% by weight, even more preferred below 1 % by weight and most preferred of not more than 0.5% by weight, in each case based on the overall weight of the fibres respectively particles before any drying step h) and/or any thermal imidation of polyamic acid fibres in step c) or polyamic acid particles in step e) is carried out.
  • Various techniques can be used for this, preferably washing f) and/or solvent exchange g), most preferably washing f).
  • Washing in step f) can be done with polymer fibre(s) obtained from steps b) and/or c) and/or with the solvent exchanged fibres after step g). It can also be done with polyimide particle(s) and/or polyamic acid particle(s) obtained in step d1 ) or d2) or e) or with solvent exchanged particles after step g) or both can be done. Preferably washing is done of the polyimide particles after cutting in step d1).
  • the wash can take place at any temperature. Preferably, however, comparatively high temperatures are used for the wash. It is particularly preferable to heat the water to 40 to 100°C, preferably 50 to 95°C, to achieve a more effective wash.
  • the fibres and/or particles are dried in step h), preferably at a temperature in the range from room temperature to 100°C, more preferably between 50 and 90°C in recirculating gas, preferably air, or vacuum, to remove residual water and/or the exchanges solvent, preferably isopropanol and hexane.
  • the overall water and/or residual solvent content after drying is preferably in the range from 0% to 5% by weight, more preferred ⁇ 3% by weight and even more preferred in the range from 0.1% to 3% by weight in each case of the dried fibres or powder, and preferably consists of the water and/or the solvents used for solvent exchange, preferably isopropanol and hexane.
  • At least 90 mol-% of building blocks R A are 3,3’,4,4’-benzophenonetetrayl and at least 90 mol-% of building blocks R B are 2,4-toluenediyl, 2,6-toluenediyl or 4,4’-methylenediphenyldiyl, with a molar ratio of 2,4-toluenediyl to 2,6-toluenediyl of from 1 : 9 to 9 : 1 and a molar ratio of the combined amount of
  • 2,4-toluenediyl and 2,6-toluenediyl to the amount of 4,4’-methylenediphenyldiyl of from 70 : 30 to 100 : 0 or at least 90 mol-% of building blocks R A are 3,3’,4,4’-benzophenonetetrayl or
  • solvent soluble polyimides are known as P84® or P84® type 70 and have the following CAS number: 9046-51-9.
  • This solvent soluble polyimide is known as P84® HT or P84® HT 325 and has the following CAS number: 134119-41-8.
  • Polyamic acids corresponding to Formula (2) and to the preferred embodiments described before are also preferably used.
  • DE 21 43 080 describes the manufacture of solvent soluble polyimides made from BTDA and mixtures of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate and 4,4’-methylenediphenyl-diisocyanate. It also describes the manufacture of solvent soluble polyamic acid from BTDA and mixtures of toluene-2,4- diamine, toluene-2,6-diamine, 4,4’-methylenediphenyl-diamine as well as the subsequent imidation to the corresponding polyimide.
  • the aromatic polyimide or aromatic polyamic acid provided in step a) is a solvent soluble a block-copolyimide or block-copolyamic acid, i.e. copolymer comprising, preferably consisting of, the blocks (A) as per the ensuing formulae (3a), or (3b) and (B) as per the ensuing formulae (4a) or (4b):
  • Said blocks A and B have a differing composition, i.e. the pairs Ri and R3 on the one hand and R2 and R4 on the other cannot each be identical at one and the same time.
  • the block copolyimide comprises a continuous phase of block A.
  • the functional group Ri therein comprises either or both of the following functional groups:
  • R2 comprises at least one or 2 or 3 of the following functional groups
  • AF1 100 mol% Rib and 64 mol% R2a, 16 mol% R2b and 20 mol% R2C.
  • Block B is elected to be a polymer that is distinctly more permeable than block A.
  • R3 in block B comprises at least one or more of the following functional groups:
  • block (B) has the following composition:
  • AF3 40 to 60 mol% Rsa, 0 to 10 mol% Rsb, 60 to 30 mol% R3C and 90 to 100 mol% R4a, 0 to 10 mol% R4b and 0 to 10 mol% R4C.
  • AF3 and AF4 relate to the functional groups R3 and R4, respectively, in total, so the amounts of the various units are each selected such that they sum to 100 mol% for each of these groups.
  • the block lengths n and m of blocks A and B are preferably in the range from 1 to 1000, more preferably in the range from 1 to 500, yet more preferably in the range from 1 to 200, yet still more preferably in the range from 5 to 150, yet still more preferably in the range from 10 to 100, yet still even more preferably in the range from 10 to 50 and most preferably in the range from 10 to 40.
  • the block lengths of blocks A and B may be the same or different.
  • the block-copolyimide or block- copolyamic acid may further exhibit some distribution with respect to the particular block lengths of blocks A and B; that is, not all bocks A or all blocks B need to have the same length.
  • the ratio between blocks A and B may thus be varied across a wide range.
  • Proportions in the block copolyimide or block-copolyamic acid of this second preferred embodiment of the present invention may be from 5 to 90% for block B and from 10 to 95% for block A. Particular preference is given to the ratio of A: B - 80:20 or 70:30 or 60:40 or most preferably 50:50.
  • the solvent soluble polyimide(s) or polyamic acid(s) used in the process of the invention is/are selected from the group consisting of Matrimid 5128 (CAS No 104983-64-4, based on BTDA DAPI [Diaminophenylindane]).
  • polyimide(s) or polyamic acid(s) comprising at least 90 % by weight, more preferred 90 to 100% by weight, even more preferred 95 to 100% by weight, particular preferred 98 to 100% by weight and most preferred 99 to 100% by weight of a polyimide or polyamic acid of recurring units according to formula (1a) or formula (1 b) or of any other of the preferred polyimide(s) or polyamic acid(s) defined above are used in step a).
  • the use of cutting machines instead of mills in the process of the invention results in much more homogeneous particles with a very narrow size distribution with regard to particle length and particle diameter.
  • the average particle diameter xso, Fmin as well as the average particle length X50, LF, can be controlled very good via the spinning and cutting conditions. It is, thus, preferred that the fibres being cut in step d) having a rectangular shape, more preferred having a sharp rectangular shape, wherein for the terms “rectangular fibre shape “ and “sharp rectangular fibre shape” the definitions provided above for the inventive particles, referring to AST F 1877 - 16, in particular Fig. X2.21 , shall be apply analogously for the fibres.
  • the shape of the front and back cross-section of the fibres can be controlled with the spinning process, too.
  • the polymer solution obtained in step a) is spun by use of a spinneret having one or more orifices, preferably 20 to 800 orifices.
  • the spun fibres pass through a spin tube where a spin gas, which is passed through the spin tube in the opposite direction, flows around the fibres.
  • a spin gas which is passed through the spin tube in the opposite direction, flows around the fibres.
  • the fibre solidifies and most of the aprotic dipolar solvent is removed.
  • the initially rather regular shape of the fibre cross-section which correlates to the geometry of the orifice, becomes irregular, preferably lobed or serrated.
  • the diameter of the fibre shrinks to preferably 10 to 25 % of the original orifice diameter.
  • orifices are used with a diameter of 100 to 300 pm, preferably 150 to 250 pm, more preferred 180 to 220 pm.
  • the extrusion speed may be 20 to 100 m/min,.
  • the amount of spin gas preferably is in the range of 40 to 100 m 3 /h, more preferred 50 to 90 m 3 /h and most preferred 60 to 80 m 3 /h and its temperature is preferably in the range of from 200 to 350°C, more preferred 250 to 300°C and most preferred 260 to 280°C.
  • the orifices of the spinneret are usually positioned beneath the surface of the liquid in a spinning bath.
  • a coagulation bath comprising a coagulant fluid, wherein the coagulant fluid is chosen from a variety of non-solvent or mixtures of solvents and nonsolvents, as long as they act in a non-solvent capacity for the poly imides or polyamic acids.
  • the aprotic dipolar solvent from the spinning solution is removed. Due to the different method to remove the content of the dipolar aprotic solvent from the spun fibres, the fibre cross-section obtained in a wet spinning process differs from that obtained in a dry spinning process.
  • the concentration of aprotic dipolar and other solvents such as, for example, but not limited to dimethylformamide, dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, sulpholane, dimethyl sulphoxide, tetrahydrofuran, dioxane, isopropanol, ethanol or glycerol in the coagulation bath in the wet spinning method is preferably between 0.01% by weight and 20% by weight, more preferably between 0.1% by weight and 10% by weight and most preferably between 0.2% by weight and 1% by weight, the remainder being water. It is likewise preferable to use pure water in the water bath.
  • the fibres produced in the process of the invention might be hollow fibres as for example described in the above cited and incorporated by reference documents WO 2015/091122 and WO 2011/009919.
  • the most preferred spinning methods of the present invention is dry spinning. It is cost efficient since large amounts of coagulation solution can be avoided and very beneficial cross-sections of the fibres can be obtained.
  • Chemical imidation is preferably done with water-withdrawing agent, more preferably acetic anhydride or propionic anhydride or benzoic anhydride or acetyl chloride or thionyl chloride in the presence of a base, more preferably with a tertiary nitrogen base, especially pyridine or triethylamine.
  • a polymer block (B) consisting of BTDA/PMDA and MesDA is used the polymer can be imidized without adding a stoichiometric amount of base.
  • a catalytic amount of a tertiary base preferably from 0.1 to 1 mol%, of preferably DABCO (diazabicyclooctane) or DBU (diazabicycloundecane), and of a slightly superstoichiometric amount, especially 5 to 30 mol% above stoichiometric, of a water-withdrawing agent, preferably acetic anhydride or acetyl chloride or thionyl chloride, most preferably acetic anhydride, led to full imidation. Details regarding the imidation of block- copolyamic acids can be extracted from WO 2015/091122, the whole content of which is hereby explicitly incorporated in the description of the present invention by reference.
  • the addition of the water-withdrawing agent is preferably first followed by continued stirring - first at -10 to 40°C, preferably at 20 to 30°C for 0.1 to 20 h, preferably 5 to 12 h, then preferably for 0.1 to 20 h, preferably for 5 to 12 h, at elevated temperature, preferably at 40 to 120°C, more preferably at 50 to 90°C, to complete the reaction.
  • Thermal imidation is carried out preferably at temperatures above 200°C, more preferred 200 to 350°C. It might be beneficial to apply specific temperature profiles during thermal imidation as described in CN 109734909 A, the whole content of the documents is hereby explicitly incorporated in the description of the present invention by reference.
  • an average particle length XSO.LF in the above defined ranges is beneficial for good solubility of the particles. They found out that polyimide particles having a length XLF above 350 pm may clump during dissolution and are thus more difficult to dissolve. In some cases, they cannot be dissolved. It is thus, preferred that less than 5% by weight, more preferred less than 3% by weight, even more preferred less than 2% by weight and most preferred 0 to 1 % by weight of the sum of all particles having a length XLF above 350 pm.
  • Cutting of the fibres can in principle be done by any suitable machine or device.
  • cutting can be done with one or more blades.
  • the blades act as a guillotine, where the fibres are cut generally perpendicular to their length.
  • Other useful methods may be for example include cutting by laser, waterjet, air jet, or any combination thereof.
  • the polymer fibre(s) is/are cut with a blade or with a guillotine cutting machine.
  • the distance the fibre(s) move(s) respectively is/are moved in between cuts may be referred to herein as cutting intervals and may define the length of the particles.
  • Cutting of the fibres may be carried out at particular cutting intervals corresponding to a desired length of the plurality of polyimide particles.
  • the polyimide particles are moved by a constant cutting interval between cuts.
  • the cutting intervals can vary.
  • the intervals can be generally the same for a desired number of cuts, and then can be changed to a different interval or the intervals can vary throughout a cutting operation.
  • the polymer fibre(s) can be moved by, for example, a movable clamp.
  • the clamp may compress the polymer fibres and then move them a predetermined length between cuts.
  • the polymer fibres can be compressed before and or during cutting. Compression of the fibres can reduce the space in between fibres and improve the cutting efficiency. It is also preferred to fix the fibre(s) after each moving and before each cut. This can be beneficial to obtain a good and homogeneous particle size distribution.
  • multiple polymer fibres are being aggregated to a yarn or tow before cutting.
  • a plurality of polymer fibres may be aggregated to form a polymer yarn.
  • Aggregating a plurality of polymer fibres may include any process of placing, collecting or combining the plurality of polymer fibres into a single group or cluster of polymer fibres to form the polymer yarn. Aggregating the polymer fibres into a polymer yarn may be done with or without twisting the plurality of polymer fibres together.
  • a polymer tow may be formed from a plurality of polymer yarns.
  • the process may include aggregating the plurality of polymer yarns to form the polymer tow.
  • Aggregating a plurality of polymer yarns may include any process of placing, collecting or combining the plurality of polymer yarns into a single group or cluster of polymeric based yarns to form the polymeric based tow.
  • Aggregating the plurality of polymer yarns into a polymer tow may be done with or without twisting the plurality of polymer yarns.
  • the polyimide particles of the invention may be obtained by either cutting individual fibres or a plurality of fibres or a yarn or a plurality of yarns or a tow or of a plurality of tows or of an aggregated tow.
  • the aggregated polymer tow is cut, it is the plurality of polymer fibres, which have been aggregated together to form polymer yams, polymer tows and ultimately that aggregated polymer tow, that separate after being cut to create the plurality of polymeric based particles.
  • FIG. 2a to 2d Use of the cutting technology, in particular of the preferred methods described before, allows to obtain fibres with a sharp rectangular shape (see Figures 2a to 2d).
  • Most of the particles have a rectangular shape with some particles having a square or trapezoidal shape.
  • the very homogeneous particle shapes and particle size distribution of the fibres of the invention contribute to a higher tamped density, excellent dissolution and lower dust formation compared to polyimide powders obtained by milling or precipitation.
  • Figures 4a and 4b show a non-inventive powder obtained by milling polyimide fibres.
  • the particle size distribution is very broad with a significant amount of small and rather spheroidal particles.
  • Figure 6 shows a commercially available polyimide powder obtained by precipitation and milling technology. The particles are none rectangular and the particle size distribution is broad.
  • Too short particles having a particle size below the range specified above are usually not or only in a minor amount, preferably 0 to 10 wt. %, more preferred 0.001 to 5 wt. %, even more preferred 0.01 to 2%, most preferred 0.1 to 1 wt.% of the overall powder weight, obtained.
  • the cutting process is very efficient and the amount of waste, that has to be disposed or re-processed, for example by redissolution, re-precipitation and re-cutting, is very low compared to milling methods where the particle size cannot be controlled exactly, and large amounts of very small particles are obtained (see Figures 4a and 4b).
  • the inventive powder comprises particles of solvent soluble aromatic polyimides.
  • the particles comprise at least 90 % by weight preferably 90 to 100% by weight, more preferred 95 to 100% by weight and most preferred 98 to 100% by weight of a solvent soluble aromatic polyimide, more preferred of a polyimide comprising recurring units of formula (1a), even more preferred of one or more polyimides described as preferred embodiments above.
  • the polyimides may comprise identical or different recurring units according to formula (1a).
  • the particles of the invention having an average length XSO.LF of from 30 to 250 pm, preferably 40 to 200 pm, even more preferred 50 to 180 pm, especially preferred 50 to 150 pm and most preferred 60 to 100 pm.
  • the particle length span (X9O ; LF - XW;LF) / XSO;LF, i.e. the particle length distribution, is preferably in the range of from 0.1 to 2.5, more preferred 0.3 to .2 even more preferred 0.5 to 1.8, particular preferred 0.5 to 1.5 and most preferred 0.5 to 1.2 to ensure a narrow particle size distribution.
  • Handling and transport properties, e.g. low dust formation, as well as fast and homogeneous solubility as well as mechanical properties of the polyimide particles of the invention are particular good if the particle length distribution is narrow. It can be further improved, if particle diameter distribution is narrow, too, and/or if the particle diameter is not too small. It is thus, preferred if the polyimide particles have an average minimum Feret diameter xso, Fmin of from 10 to 100 pm, preferably 10 to 80 pm, more preferred 20 to 70 pm, even preferred 30 to 70 pm and most preferred 30 to 60 pm and/or a particle diameter distribution, i.e. span (x90; Fmin - xio; Fmin) I xso; Fmin, of from 0.1 to 2.5, more preferred 0.2 to 2 even more preferred 0.3 to 1.5, particular preferred 0.4 to 1.2 and most preferred 0.5 to 1.0
  • the particles of the invention preferably having a monomodal particle length distribution for particles with XLF > 30 pm and/or a monomodal particle diameter distribution for particles with XFmin > 20 pm.
  • the process of the invention has the advantage that the fibres are cut while the geometry of the fibre is maintained. It is therefore possible and preferred to obtain polyimide particles having a cross-section having an irregular shape.
  • the inventive polyimide particles are preferably obtained by cutting of a fibre having an irregular, preferably lobed or serrated, cross-section.
  • the cross-section of the particles preferably has an irregular shape, more preferred a lobed or serrated shape, most preferred is a multiloba! form.
  • the irregular shape can be verified by image analysis of the cross-section of the powders but can also be seen in a side view of the particles, perpendicular to the cross-section. In the side view of a two- dimensional black and white image of the particles, stripes can be seen in black, grey and wide colors (see Figures 2a to 2d).
  • the polyimide particles of the invention can be used in all known applications for solvent soluble polyimides. Since the process of the invention allows to obtain solvent soluble polyimide powders with high molecular mass, the powders of the invention show superior performance compared to commercially available polyimide powders made from the same polymer but via precipitation and milling.
  • the polyimide powder of the present invention can preferably be used for hot compression molding, to produce polyimide coatings of substrates and as fillers for finished or semi-finished polymeric products, for example made of PTFE. They can also be used as raw material to produce fibres or hollow fibres or flat sheet and the respective membranes, which can be used in hot gas filtration (fibres) or gas or liquid separation (hollow fibre and flat sheet membranes). Because of the high bulk density and low dust formation as well as of the good solubility the polyimide powder of the invention is superior to the prior art if it is used to store and transport the polyimide from the production site to the site where it is used and further processed.
  • a two-dimensional picture of the particles was obtained by Sympatec QicPic/L02 with the measurement setting M6.
  • the particle shape was evaluated by use of a two-dimensional image obtained via image analysis in accordance with ASTM F 1877 - 16.
  • the minimum Feret diameter XFmin is defined in accordance with DIN ISO 9276 - 6 : 2012-01 as the minimum distance between pairs of parallel tangents to a projected outline of the particle to be evaluated. It is determined via image analysis of a two-dimensional image (see Figure 1).
  • the span (breadth) of the minimum Feret diameter distribution curve calculates as:
  • Bulk density is measured according to ISO 60 with a SMG 53466 from Powtec.
  • DMSO dimethylsulfoxide
  • the residual solvent content is automatically computed according to the formula area
  • Residual dipolar aprotic solvent of the moist polymer, fibre or powder sample is determined by Soxhlet extraction in ethanol. Subsequent quantification is by direct injection of the extract onto GC.
  • the polyimide particles obtained are shown in Figures 1 and 2a to 2d.
  • the particles have a sharp shape.
  • Most of the particles have a rectangular shape (Figure 2b) and only a minor number of particles having a square ( Figure 2c) or trapezoidal (Figure 2d) shape.
  • Stripes at the side view confirm the irregular shape of the cross-section of the particles that was maintained during cutting.
  • Analytic data of the particles are given in Table 1 .
  • Particle length distribution xso, LF and particle diameter distribution xso, Fmin are shown in Figures 3a and 3b.
  • Fibre filaments of polyimide P84® Type 70 (same polymer solution as in Example 1 ) having a length of 5 mm, were prepared via dry spinning according to US4,801502 B2. The filaments were washed in in 4 washing cycles at room temperature in demineralized water in a mass ratio 1 :40 (filaments : water) to remove DMF and then dried in a hurdle dryer at 80°C with circulating air. The dried fibre bulk was then milled by using a Retsch ZM200 laboratory mill: Two times milling at 18000 mim 1 with 0.25 mm mill insert. The fibre powder was then sieved with 250 pm sieve insert in a Retsch AS200 laboratory sieve tower.
  • Example 2 The molecular mass Mn of the polyimide polymer used as raw material in Example 1 and Comparative Example 1 was compared with the molecular mass distribution of the final polyimide powder obtained in Example 1 respectively Comparative Example 1 as well as to the molecular mass distribution of the powder of Comparative Example 2. The results are given in Table 2.
  • Example 1 and Comparative Example 2 is shown in Table 3
  • Table 3 shown that semi-finished HCM parts made out of polyimide powders have higher mechanical strength compared to part made from commercially available polyimide powders, even though both powders were made from the same polyimide.

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Abstract

L'invention se rapporte à de nouvelles poudres de polyimide solubles dans un solvant ayant un poids moléculaire élevé et des propriétés améliorées, qui peuvent être préparées de manière simple par découpe de fibres, qui ont été préparées à partir d'une solution de polyimide ou d'acide polyamique dans un solvant aprotique dipolaire, par réaction d'un ou de plusieurs dianhydrides d'acide tétracarboxylique aromatiques avec un ou plusieurs diisocyanates aromatiques, respectivement des diamines aromatiques. La découpe de telles fibres à une longueur moyenne (x50, LF) de 30 à 250 µm peut être effectuée avec une machine de découpe à guillotine, fournit des poudres à faible formation de poussière ayant une distribution granulométrique étroite.
PCT/EP2025/052054 2024-02-09 2025-01-28 Poudres de polyimide solubles dans un solvant et leur procédé de fabrication Pending WO2025168379A1 (fr)

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Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2143080A1 (de) 1970-09-25 1972-03-30 Upjohn Co Mischpolyimide
US3708458A (en) 1971-03-16 1973-01-02 Upjohn Co Copolyimides of benzophenone tetracarboxylic acid dianhydride and mixture of diisocyanates
DE2442203A1 (de) 1973-10-12 1975-04-17 Upjohn Co Mischpolyimidfasern und -faeden sowie verfahren zu ihrer herstellung
US3985934A (en) 1974-07-26 1976-10-12 The Upjohn Company Polyimide fiber having a serrated surface and a process of producing same
US4016227A (en) 1972-02-07 1977-04-05 The Upjohn Company Process for the isolation of polyimides in a solid state
EP0240302A2 (fr) * 1986-04-01 1987-10-07 Celanese Corporation Compositions de polybenzimidazole aromatique et de polyimide aromatique et procédé de préparation
EP0279807A2 (fr) 1987-02-16 1988-08-24 Lenzing Aktiengesellschaft Procédé de fabrication de poudres polymères résistant à de hautes températures et dispositif pour la mise en oeuvre de ce procédé
US4801502A (en) 1983-03-09 1989-01-31 Chemiefaser Lenzing Aktiengesellschaft Non-flammable, high-temperature resistant polyimide fibers made by a dry spinning method
WO2011009919A1 (fr) 2009-07-23 2011-01-27 Evonik Fibres Gmbh Membranes de polyimide obtenues à partir de solutions de polymérisation
WO2015091122A1 (fr) 2013-12-17 2015-06-25 Evonik Fibres Gmbh Membranes polyimidiques hautement sélectives à perméance augmentée fabriquées à partir de copolyimides séquencés
EP3375609A1 (fr) 2017-03-14 2018-09-19 Ricoh Company Ltd. Poudre de résine pour fabrication de forme libre solide et dispositif de fabrication d'un objet de fabrication de forme libre solide
CN109734909A (zh) 2019-01-16 2019-05-10 江苏先诺新材料科技有限公司 一种聚酰亚胺粉体及其制备方法

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2143080A1 (de) 1970-09-25 1972-03-30 Upjohn Co Mischpolyimide
US3708458A (en) 1971-03-16 1973-01-02 Upjohn Co Copolyimides of benzophenone tetracarboxylic acid dianhydride and mixture of diisocyanates
US4016227A (en) 1972-02-07 1977-04-05 The Upjohn Company Process for the isolation of polyimides in a solid state
DE2442203A1 (de) 1973-10-12 1975-04-17 Upjohn Co Mischpolyimidfasern und -faeden sowie verfahren zu ihrer herstellung
GB1432285A (en) * 1973-10-12 1976-04-14 Upjohn Co Polyimide filament and process for its manufacture
US3985934A (en) 1974-07-26 1976-10-12 The Upjohn Company Polyimide fiber having a serrated surface and a process of producing same
US4801502A (en) 1983-03-09 1989-01-31 Chemiefaser Lenzing Aktiengesellschaft Non-flammable, high-temperature resistant polyimide fibers made by a dry spinning method
EP0240302A2 (fr) * 1986-04-01 1987-10-07 Celanese Corporation Compositions de polybenzimidazole aromatique et de polyimide aromatique et procédé de préparation
EP0279807A2 (fr) 1987-02-16 1988-08-24 Lenzing Aktiengesellschaft Procédé de fabrication de poudres polymères résistant à de hautes températures et dispositif pour la mise en oeuvre de ce procédé
US4897227A (en) * 1987-02-16 1990-01-30 Lenzing Aktiengesellschaft Process for producing high-temperature resistant polymers in powder form
WO2011009919A1 (fr) 2009-07-23 2011-01-27 Evonik Fibres Gmbh Membranes de polyimide obtenues à partir de solutions de polymérisation
WO2015091122A1 (fr) 2013-12-17 2015-06-25 Evonik Fibres Gmbh Membranes polyimidiques hautement sélectives à perméance augmentée fabriquées à partir de copolyimides séquencés
EP3375609A1 (fr) 2017-03-14 2018-09-19 Ricoh Company Ltd. Poudre de résine pour fabrication de forme libre solide et dispositif de fabrication d'un objet de fabrication de forme libre solide
CN109734909A (zh) 2019-01-16 2019-05-10 江苏先诺新材料科技有限公司 一种聚酰亚胺粉体及其制备方法

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