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
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/88—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds
  • D01F6/90—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from mixtures of polycondensation products as major constituent with other polymers or low-molecular-weight compounds of polyamides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • 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
  • 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
  • D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides
• • 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
• • 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
  • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
  • Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
  • Y10T442/696—Including strand or fiber material which is stated to have specific attributes [e.g., heat or fire resistance, chemical or solvent resistance, high absorption for aqueous compositions, water solubility, heat shrinkability, etc.]

Definitions

• the present invention relates to a method of manufacturing a nonwoven article containing nanofibers and a nonwoven article containing such fibers. These articles are particularly useful in fluid filtration systems containing particles or in membrane separation systems used in the textile industry. These items are more commonly used in the textile industry.
• the fibers obtained by electrospinning have a section of dimension between 5 and 500 nm.
• the nonwoven articles obtained with such fibers have a high specific surface area which favors many applications such as, for example, use as a filter media, separation membranes and as an element for the manufacture of protective clothing.
• Many studies on the transformation of polymers by electrospinning have been carried out.
• the document BR 0313222-6 describes the conditions for the electrospinning of amorphous, biodegradable polymers containing a biological agent (such as DNA, peptide, vaccine) for pharmaceutical applications.
• polyamide 6/6 solutions in formic acid are electrospunted through a grounded syringe and by applying a negative voltage (-20 kV) to the collector.
• the polyamide concentration of the solutions used is between 0.10 g / cm 3 and 0.16 g / cm 3 and the diameter of the section of the fibers is between 0.70 ⁇ m and 2.8 ⁇ m.
• These micron-sized diameters are suitable for ultrafiltration, but are not, for example, for filtering fluids comprising particles.
• the present invention proposes an electrospinning process which, compared to the methods described:
• the polyamides that are suitable for being dissolved have a number-average molecular weight advantageously between 10,000 g / mol and 50,000 g / mol, preferably between 18,000 and 50,000 g / mol.
• the polyamide solution may contain salts such as metal chlorides, such as, for example, sodium chloride, hexahydrate aluminum chloride, magnesium chloride, ammonium chloride. or iron chloride.
• This salt is present, advantageously at a concentration of between 5 mg / cm 3 and 80 mg / cm 3 .
• the concentration of salts will advantageously be between 25 mg / cm 3 and 60 mg / cm 3 .
• the polyamide solution of the invention does not comprise any additional polymeric organic additive.
• the invention makes it possible to obtain a nonwoven article constituted by nanofibers having a diameter of the section between 40 and 350 nm.
• These articles or nonwoven webs can be used as separation membranes or filter medium for systems comprising particles, cells, polar or non-polar solvents, filters, humidity sensors, for example.
• This manufacturing method can be used for the production of large nonwoven webs by using large size collectors and several spinning syringes.
• the method can be used for the manufacture of nanofibers for the production of a continuous filament, of interest for the yarn and clothing market.
• nanofibers of polyamide, in particular polyamide 6.6 of section between 40 and 350 nm is achieved by using a metal electrode (eg, aluminum, brass, copper or alloys of these metals) immersed in the polyamide solution.
• the method is implemented with working distances between the needle and the collector of between 5 and 50 cm, needles with a diameter of between 0.2 and 3 mm and a length of between 10 mm and 50 mm.
• the speed of rotation of the collector is between 5 and 300 rpm (revolutions per minute).
• the collectors are made of various metallic materials such as brass, aluminum, copper, stainless steel and alloys of these metals.
• the process is carried out with humidity conditions of between 20% and 80%.
• the positive / negative voltage between the needle and the collector is between 5 and 50 kV, the collector being advantageously connected to the ground.
• the collector is advantageously of cylindrical shape but it can be a flat or curvilinear plate, a flat grid or the like.
• the spinning and collecting time on the roll can be between 1 second and 1 hour.
• the process for obtaining the nanofiber-containing product according to the invention uses a method for electrospinning a polymer solution containing one or more polyamide homopolymers or copolymers, in the presence or absence of ionic salts, the solvent being an organic solvent.
• the polyamides suitable for the process of the invention advantageously have a number-average molecular weight of between about 10,000 g / mol and about 50,000 g / mol, preferably between 18,000 and 50,000 g / mol.
• These polyamides are advantageously obtained with a post-condensation step in solid or melt phase, preferably with a solid phase post-condensation step.
• the nanofibers obtained with the process of the invention have a section of average diameter between about 40 nm and about 350 nm.
• the electrospinning process of a polymer solution consists in applying an electrical potential difference between the solution and the collecting surface to obtain non-woven articles or webs consisting of nanofibers of nanometer-sized section.
• An electrode connected to a positive (or negative) high voltage source is - s -
• Nanofibers or solidified nanofibrilic membranes are deposited on a collector.
• This collector may be a rotary drum covered with an electrically conductive metal or an electrically conductive metal gate. The collector is connected to the ground.
• the concentration of the polymer in the solution the difference of electric potential applied to the solution, the effect of the addition of the ionic salts in the solution, the flow of the solution at the outlet of the capillary or needle and the distance between the end of the capillary and the collector.
• Suitable polyamides are mainly homopolymers or copolymers of polyamide, selected from the group comprising: polyamide 66, 6, 610, 612, 11 and 12, their mixtures or alloys, and copolymers of these polyamides, or derivatives thereof.
• the preferred polyamide of the invention is Polyamide 66.
• the present invention makes it possible to manufacture articles or non-woven fabrics comprising, in particular, polyamide 66 nanofibers with a diameter of between 40 and 350 nanometers.
• the main object of this invention is the manufacture of webs made of nanofibers obtained by electrospinning polyamide 66 solutions in solvents with optimal process parameters including the distance between the capillary and the collecting surface, the potential difference applied between the solution and the collector, the presence of ionic salts in the solution, the concentration in polymer of the solution, the shape of the webs, nanofibres and membranes obtained. These conditions are determined to obtain articles suitable for use in the production of filters, separation membranes, protective clothing or son.
• the polymer solution suitable for the invention comprises polyamide 66 and an organic solvent. It also includes and advantageously a salt to obtain articles or fabrics made of smaller or finer section fibers.
• the solutions are characterized by the determination of the surface tension, the electrical conductivity and their rheology.
• the canvases obtained from these solutions were studied by scanning electron microscopy in particular to determine the average diameter of the microfibers.
• solvents may also be used, such as: hexaisofluoropropanol, acetic acid / formic acid mixtures, sulfuric acid / formic acid, ethanol / formic acid, hexaisofluoropropanol / dimethylformamide and formic acid / m-cresol, or mixtures thereof .
• Other salts can also be used such as: sodium chloride, aluminum chloride hexahydrate, magnesium chloride, ammonium chloride and iron chloride, or mixtures thereof.
• a metal electrode immersed in the solution the metal may be aluminum, brass, copper and alloys of these metals
• the distance between the end of the capillary and the collector varies from about 5 cm to about 50 cm
• the diameter of the needle or capillary varies from about 0.2 mm to about 3 mm
• the length of the needle varies between about 10 mm to about 50 mm
• the collector rotation speed varies from about 5 rpm to about 300 rpm - different moisture conditions vary from about 20% to about 80% and positive or negative electrical potential differences range from about 5 kV to about 50 kV.
• the collector comprises or comprises an outer surface of electrically conductive metal and may be selected from the group consisting of brass, aluminum, copper, stainless steels and their alloys.
• the collector used, electrically connected to the earth is preferably of cylindrical shape. However, without departing from the scope of the invention, it may be of various shapes such as flat plate, curvilinear, flat grid, for example.
• the collector is preferably electrically grounded, but a positive or negative high voltage (between 5 kV to 50 kV) can be applied instead of electrically grounded.
• the important feature of the process is that there is a high potential difference between the solution and the collector for generating electrical forces to obtain a cone at the capillary outlet and a solution jet from this cone.
• the collection time of the nanofibers on the collector can vary between one second and about one hour.
• the product obtained by the process according to the invention is preferably in the form of a nonwoven web or web.
• FIGURE 1 schematically illustrates an embodiment of a device for implementing the electrospinning process. of the invention.
• the device shown in this figure comprises: a high voltage source (1); a glass syringe or capillary (piston not shown) (2) with a cannula at its end; a conductive metal electrode (3) and a collector (4).
• a high electrical potential (positive or negative) is applied to the solution of the polymer by means of the metal electrode (3).
• the polyamide solution forms several jets of polyamide solution, generated at the outlet of the needle.
• the solvent evaporates between the end of the needle and the collector (4), electrically connected to the earth.
• the nanofibers are collected on the collector and form a non-woven fabric. Examples will be described below to illustrate the invention, but in no case should they limit the scope and scope of the invention.
• a solution of polyamide 6.6 with a number average molecular weight of 500 g / mol in formic acid with a concentration of 150 mg / cm 3 of polymer and 10 mg / cm 3 of sodium chloride was introduced into a glass syringe and converted into nanofibers in an electrospinning device according to that shown in Figure 1.
• the solution is placed in the syringe (2), a potential difference of 20 kV is applied between the solution or the syringe by the copper electrode (3), and the collector (4).
• the solution exiting the syringe forms elongating jets which are collected on the collector, the solvent is evaporated during the jet path.
• the length of the needle at the syringe outlet is 30 mm, the diameter of the needle orifice is 0.7 mm and its end is disposed at 10 cm from the surface of the collector.
• the process is carried out for 20 minutes with a speed of rotation of the collector cylinder of 23 rpm.
• the fabric thus formed on the collector is recovered.
• Example 1 is repeated but using a solution of polyamide 66 with a number average molecular weight of 19,000 g / mol at a concentration of 170 mg / cm 3 in the absence of ionic salt.
• the potential difference applied to the solution is 15 kV.
• the length of the needle at the exit of the syringe is 10 mm, the diameter of the orifice of the needle is 0.8 mm and its end is disposed at 5 cm from the surface of the collector.
• the process is carried out for 10 minutes with a rotation speed of the collector cylinder of 15 t.p.m ..
• the fabric thus formed on the collector is recovered.
• Example 1 is repeated but using a solution of polyamide 66 with a number average molecular weight of 15,000 g / mol at a concentration of 150 mg / cm 3 in the absence of ionic salt.
• the potential difference applied to the solution is 25 kV.
• the length of the needle at the syringe outlet is 30 mm, the diameter of the needle orifice is 0.7 mm and its end is disposed at 10 cm from the surface of the collector.
• the process is carried out for 15 minutes with a rotation speed of the collector cylinder of 20 t.p.m .. The fabric thus formed on the collector is recovered.
• FIG. 1 is a microscope view illustrating the morphology and structure of the article obtained in Example 3.
• Figure 3 shows the nanofiber diameter distribution, illustrating the mean diameter at 189 nm.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Textile Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Nanotechnology (AREA)
• Composite Materials (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Materials Engineering (AREA)
• Crystallography & Structural Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Nonwoven Fabrics (AREA)
• Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
• Woven Fabrics (AREA)

Applications Claiming Priority (2)

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• 2007
  • 2007-01-05 FR FR0700053A patent/FR2911151B1/fr not_active Expired - Fee Related
• 2008
  • 2008-01-04 EP EP08709712A patent/EP2115190A1/de not_active Withdrawn
  • 2008-01-04 WO PCT/IB2008/000009 patent/WO2008084369A1/fr active Application Filing
  • 2008-01-04 US US12/522,028 patent/US20100173551A1/en not_active Abandoned
  • 2008-01-04 BR BRPI0806183-1A patent/BRPI0806183A2/pt not_active IP Right Cessation
  • 2008-01-04 CN CNA2008800046864A patent/CN101605931A/zh active Pending

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