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
  • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P1/00—Drugs for disorders of the alimentary tract or the digestive system
  • A61P1/02—Stomatological preparations, e.g. drugs for caries, aphtae, periodontitis
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P17/00—Drugs for dermatological disorders
  • A61P17/02—Drugs for dermatological disorders for treating wounds, ulcers, burns, scars, keloids, or the like
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P9/00—Drugs for disorders of the cardiovascular system
  • A61P9/14—Vasoprotectives; Antihaemorrhoidals; Drugs for varicose therapy; Capillary stabilisers

Definitions

• the present invention relates to a new process for spinning chitosan or its derivatives.
• spinning is an operation for producing fibers or filaments capable of leading to a thread after elongation and / or twisting.
• Chitosan a deacetylated derivative of chitin
• Chitosan and chitin are both copolymers with the same overall chemical structure and are distinguished only by the relative proportion of the N-acetyl glucosamine and glucosamine units constituting them, that is to say their degree of acetylation.
• the viscosity of chitosan depends on its degree of acetylation: the more it is deacetylated, the more free amino groups there are, the more the chitosan is soluble in the dilute acids which protonate its amino groups, and therefore the higher its viscosity. ; viscosity of chitosan also depends on its concentration, on its temperature since the viscosity drops when the temperature increases and on the pH conditions in which it is placed. It can also depend on the deacetylation process used to obtain it. As with any polymer, it also depends on its molecular distribution, characterized in particular by its weight-average molecular weight M w .
• extrusion unit is then used on a laboratory scale, namely an experimental spinning bench which consists of a reservoir, a metering pump and an extrusion die with 20 holes of 80 ⁇ m in diameter.
• the filaments are coagulated in a dilute sodium hydroxide (NaOH) bath, about 100 cm long, then they are drawn with rollers in hot water at 80-85 ° C, then washed and dried on rollers in chrome under radiant heat.
• NaOH sodium hydroxide
• Chitosan has many properties, and is used in a large number of industries, however its price, which remains high, has been a limiting factor for its development.
• the wiring of chitosan requires significant installations, and the quality control of the various stages is particularly important when the chitosan is intended in particular for medical applications.
• the inventors have therefore sought to simplify the processes of the prior art, so as to allow easier industrial implementation, and to reduce the manufacturing costs of chitosan fibers by reducing the amount of chitosan used and the treatment of waste. .
• the method according to the invention provides the advantage of avoiding the use of a soda bath and eliminates a bath in the spinning bench.
• the proposed method plays an important role in the mechanical properties of the resulting materials.
• the subject of the invention is therefore a new process for spinning chitosan according to which a solution of chitosan is prepared at a certain concentration by weight of polymer called collodion, by dissolving chitosan in an aqueous solution of weak acid at stoichiometry with respect to the free amine functions on the chitosan, we filter, we degass, we extrude this collodion and we submit it to the coagulating action of a gas which is capable of deprotonating the ine functions and making them insoluble in water and thus make the collodion coagulate.
• the collodion is a solution concentrated in chitosan.
• the method according to the invention uses chitosan whose molar mass is high, which makes it possible to have a high collodion viscosity for a low concentration of chitosan, and at the end of the method, to obtain yarns having good mechanical properties superior to those obtained with lower molar masses.
• the concentrated chitosan solution must have an apparent viscosity sufficient to allow the solution to be extruded.
• the chitosan used for implementing the process according to the invention has a degree of acetylation preferably less than 5%, determined according to the technique described by the US Pharmacopoeia, ie, by NMR spectroscopy of the proton " ""H
• the DA is then calculated by the Hirai et al method (Hirai A, Odani H, Nakajima A. Determination of degree of deacetylation of chitosan by 1 H NMR spectroscopy. Polym. Bull. 1991, 26, 87).
• Chitosan used can also be selected on the fact that it has a high molar mass average, preferably greater than 500,000 g / mol.
• the mass average molar mass is determined according to the technique recommended by the American Pharmacopoeia, ie, by static light scattering coupled with size exclusion chromatography, taking into account the increment of refractive index of the polymer, dn / dc for the solvent used.
• the concentration of the chitosan solution is between 1 and 3% by weight, preferably 2% by weight.
• the viscosity is preferably between 100 and 1500 poises and preferably around 600 poises.
• the high molecular weight chitosan is dissolved in an aqueous weak acid solution, the acid being added in stoichiometric amount in relation to the amino functions.
• the weak acid used to dissolve the chitosan and prepare the collodion is acetic acid.
• the collodion is then extruded, and the filament leaving the extrusion die is brought into contact with a coagulating gas.
• this gas is ammonia.
• filament is defined within the meaning of the present invention as a very long fiber, the fiber being the element of material which constitutes the basic element of a textile material, woven or nonwoven.
• a stretching is carried out during the coagulation step, that is to say while the collodion filament leaving the extrusion die, is subjected to a coagulating gas action .
• the drawing can be carried out hot or cold and aims to lengthen the continuous filaments and to orient the crystal structure of the polymer fibers constituting the filaments, in order to improve the mechanical properties of the resulting wire or filament.
• the drawing speed of the extruded chitosan is between 1 and 20 times the speed of extrusion.
• the drawing is carried out by means of reels and the drawing speed must be greater than or equal to the extrusion speed, namely the ratio of the flow rate over the section of the extruded chitosan.
• the step of bringing the extruded collodion filament into contact with the gas is followed by a washing step, prior to drying.
• the objective of washing is to eliminate the weak acid salts used to dissolve the chitosan and prepare the collodion, these salts forming in the extruded chitosan during contact with the coagulating gas.
• the washing step consists in passing the extruded, coagulated and at least partially drawn chitosan through a bath of demineralized water which is agitated and replaced continuously to ensure a treatment flow rate of approximately 25 ml of water per mm 3 of chitosan fiber.
• the weak acid for solubilization of chitosan in the first step, is acetic acid and the gas coagulating the filament at the outlet of extrusion is ammonia: the ammonium acetate salts formed inside the still partially drawn wire during coagulation, in the presence of ammonia gas, are known to be easily hydrolyzed to generate both ammonia and acetic acid. These molecules are relatively poorly soluble in water and are easily extracted in the form of gas by evaporation of the solution.
• the method does not include a step of washing the extruded and drawn chitosan: the drying step is chained directly after the coagulation step.
• the invention also relates to a chitosan spinning device characterized in that it comprises an extrusion die placed in a gaseous atmosphere.
• the gas can flow from bottom to top in a closed circuit, with a controlled flow.
• the device according to the invention comprises a continuous air heating system regulated in temperature, preferably between 40 and 110 ° C, and ventilated.
• the device according to the invention also comprises at least one system for drawing the extruded chitosan which can operate simultaneously with the heating system.
• the device comprises: a reactor vessel provided with a stirring assembly and with a complete vacuum generator group a positive displacement volumetric pump "titration" ensuring a constant flow of a value given in chitosan - an assembly carrying the spinning head a coagulation chamber allowing the application of gas on the extrusion outlet two winding systems for drawing the fibers - a washing tub a drying assembly
• the extrusion die is of variable dimensions, preferably of diameter less than or equal to 0.8 mm and of length less than or equal to 25 mm.
• the extrusion die can be monofilament or multifilament.
• the extrusion die is directly immersed in the coagulation chamber.
• the stretching system consists of two rewinder systems, the first placed at the outlet of the coagulation chamber and the second placed at the outlet. of the drying system.
• the linear drawing speeds are between 0.005 m / s and 0.15 m / s.
• the device contains a washing bath, it preferably consists of demineralized water regenerated with permanent stirring.
• the drying of the extruded and drawn chitosan is carried out at a temperature between 40 and 110 ° C.
• the subject of the invention is also a chitosan wire, characterized in that it is obtained by the process described above.
• a thread is one or more continuous strands of fibers, filaments or materials suitable for knitting or weaving or for any intertwining producing a woven or nonwoven material.
• a yarn can consist of a single filament with or without twist, a set of fibers or filaments twisted together, a set of fibers or filaments held together without twist, a narrow ribbon formed with or without torsion.
• Another object of the invention is the use of this chitosan yarn in all applications where it is of industrial interest, and in particular for the manufacture of textiles comprising woven or nonwoven chitosan, for the manufacture of woven medical devices or non-woven, for the manufacture of a reinforcing plate intended in particular for traumatic, visceral or muscular surgery, for the repair of soft tissues, for the manufacture of artificial skin, for the manufacture of a medicament intended for the treatment of ulcers varicose and sluggish wounds.
• the invention also relates to the use of the chitosan wire obtained by the above process in periodontology, to fight against the formation of caries and dental plaque, stomatitis and gingivitis.
• Another object of the invention is the use of chitosan yarn obtained by the above process in cosmetics for the manufacture of moisturizing, regenerating and protective skin products, or even for the manufacture of hair products.
• the invention also relates to the use of the chitosan wire obtained by the above process for the treatment of waste water, for fixing heavy metals, for agglomerating and then separating dispersed colloidal particles, for immobilizing industrial enzymes, for seed coating, for spreading in agriculture.
• the invention will be better understood on reading the examples which follow, which illustrate, without limitation, the invention.
• Example 1 Raw Material: Chitosan 114 (Mahtani Chitosan)
• chitosan degree of acetylation (DA): 2 ⁇ DA ⁇ 3% 500,000 ⁇ average molar mass by mass ⁇ 600,000 g / mol
• DA degree of acetylation
• the chitosan is dissolved in an aqueous solution of acetic acid, added in stoichiometric amount relative to the amino functions of the chitosan .
• the resulting solution is 2% by weight of chitosan and has an apparent viscosity greater than 620 poises.
• the solution is left in the ambient air for a few hours to ensure better degassing.
• This solution is then introduced into a 20 ml syringe, which is itself placed on a syringe pump maintained in vertical position.
• the needle at the end of the syringe having the function of die is not bevelled and has no structural defect which could lead to spinning problems. Cleaning the die is therefore an important step in the spinning process.
• the die has a diameter of 0.8 mm and a length of 22 mm.
• the extrusion speed used varies between 0.1 and 35 mL / hour.
• a piece of glassware, hereinafter called the coagulation chamber consisting of two coaxial glass tubes and sliding joints, was manufactured to create an ammonia atmosphere of variable volume and thus obtain a circulation of gas from bottom to top in circuit closed .
• the extrusion die is directly immersed in the coagulation chamber. The solution is coagulated at the outlet of the die in the presence of ammonia gas.
• the extruded chitosan will have a more or less coagulated appearance at this stage of the spinning process.
• the extruded chitosan is stretched: a drawing ratio is then applied to the extruded chitosan (drawing speed greater than the extrusion speed, the latter being directly related to the flow rate).
• the extruded and drawn chitosan is immersed in two washing baths containing distilled water with continuous stirring for respective times of one minute. Stretch again, and dry in ambient air while continuing the stretch.
• Example 2 The chitosan, acetic acid and distilled water are introduced into a 316L stainless steel reactor provided with a stirring system provided with an electronic speed variator. The chitosan is thus dissolved in a way homogeneous. The air bubbles present in the solution are removed by a degassing system. After complete dissolution of the chitosan, the resulting solution, called collodion, is filtered through a 200 ⁇ m poral filter, then extruded through a die of variable diameter, using a titration pump which can control a flow rate between 0.1 and 300 ml / hour .
• the monofilament die is a non-bevelled needle with a diameter less than or equal to 1 mm and a length less than or equal to 50 mm.
• the extrusion die is then directly immersed in a gaseous atmosphere so that, as soon as it leaves, the solution coagulates in the presence of ammonia.
• the coagulation time can vary from a few seconds to several minutes depending on the diameter of the die, the flow rate and the length of the chamber.
• the fiber then continues its course by being stretched by means of winders of variable speeds which generate a rate of drawing relative to the speed of extrusion.
• the fiber is then drawn to the washing bath, with a volume of 15 L, where the distilled water is stirred there and replaced continuously thanks to an overflow circulation.
• Example 3 Safety of the Wire Obtained by the Process According to the Invention Animal experiments were carried out on New Zealand rabbits in order to verify the safety of the chitosan material.

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• 2003
  • 2003-09-18 FR FR0350571A patent/FR2860007A1/fr active Pending
• 2004
  • 2004-09-17 EP EP04816135A patent/EP1670418A2/de not_active Withdrawn
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