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
  • D01F13/00—Recovery of starting material, waste material or solvents during the manufacture of artificial filaments or the like
  • D01F13/02—Recovery of starting material, waste material or solvents during the manufacture of artificial filaments or the like of cellulose, cellulose derivatives or proteins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B1/00—Preparatory treatment of cellulose for making derivatives thereof, e.g. pre-treatment, pre-soaking, activation
  • C08B1/003—Preparation of cellulose solutions, i.e. dopes, with different possible solvents, e.g. ionic liquids
• • 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
  • D01F2/00—Monocomponent artificial filaments or the like of cellulose or cellulose derivatives; Manufacture thereof
• • 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
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
  • Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear

Definitions

• the present invention relates to a process for producing a solution of N-methylmorpholine-N-oxide in water, which is used in the amine oxide process.
• the invention further relates to a method for producing cellulosic moldings, in particular fibers and films.
• N-Methylmorpholine-N-oxide is primarily used as the amine oxide.
• Other amine oxides are described, for example, in EP-A-0 553 070.
• a method for producing moldable cellulose solutions is known, for example, from EP-A-0 356 419.
• the production of moldable solutions of cellulose in tertiary amine oxides and their further processing into shaped bodies is generally referred to as amine oxide process for the purposes of the present description and the present patent claims.
• EP-A-0 356 419 describes an amine oxide process for producing spinnable cellulose solutions, which uses, among other things, a suspension of cellulose in liquid, aqueous N-methylmorpholine-N-oxide (NMMO) as the starting material.
• NMMO N-methylmorpholine-N-oxide
• This method consists in the suspension being continuously and continuously converted into a moldable solution in a thin-film treatment apparatus.
• the moldable solution is then spun into filaments in a molding tool, for example a spinneret, which are passed through a precipitation bath.
• the cellulose is precipitated in the precipitation bath.
• the tertiary amine oxide accumulates in the precipitation bath.
• the amine oxide content in the precipitation bath can be up to 30% by weight.
• degradation products of the amine oxide process also accumulate in the precipitation bath with the amine oxide. These degradation products can be strongly colored and thus impair the quality of the cellulosic molded articles produced. Other substances in turn can pose an additional safety risk, since under certain conditions the amine oxide tends to undergo strongly exothermic decomposition reactions and these decomposition reactions can be induced or accelerated by certain substances. These substances must be removed from the precipitation bath to be processed before the concentration and separation of NMMO.
• water is drawn off from the cleaned precipitation bath, which is optionally combined with other process waters of the amine oxide process, such as vapor condensates which are produced in the production of the cellulose solution.
• vapor condensates which are produced in the production of the cellulose solution.
• This can for example by evaporation.
• highly concentrated, aqueous amine oxide is obtained, which is recycled back into the amine oxide process.
• the vapors of the evaporation mainly consist of water, in which considerable amounts of N-methylmorpholine, the main degradation product of the NMMO, are also dissolved.
• the vapors typically contain, for example, up to 1000 mg NMMO and 240 mg N-methylmorpholine per liter. These vapors are expediently concentrated, for example by reverse osmosis.
• a process for the preparative preparation of tertiary amine oxides by oxidation of tertiary amines is known for example from EP-A - 0 092 862.
• the amine oxide is oxidized in an aqueous solvent with molecular oxygen under pressure, which solvent has a pH value which is approximately equal to or higher than the pKa value of the tertiary amine.
• DD-A-259 863 relates to the preparation of aqueous NMMO solutions by oxidation of N-methylmorpholine with H 0 and passing the reaction solution over one or more exchange columns which are filled with styrene / divinylbenzene copolymer containing sulfonate groups, and by adjusting one pH of the solution to values between 8 and 5 by adding phosphoric acid.
• DE-A -4 140 259 the production of NMMO is known, in which process the formation of nitrosamines is prevented by primary and secondary amines, for example, can be trapped with acid halides.
• EP-A-0 320 690 describes the production of essentially nitrosa-free amine oxides by oxidation using peroxides in the presence of a combination of C0 2 / ascorbic acid, which acts as a nitrosamine inhibitor.
• the oxidation with H_0 2 in water and a cosolvent, preferably a carboxylic acid ester is known.
• a cosolvent preferably a carboxylic acid ester
• the present invention therefore aims to eliminate this disadvantage and to provide a method in which the addition of fresh NMMO can be largely reduced or even avoided.
• an aqueous solution (A) which contains N-methylmorpholine and comes from the amine oxide process, after which
• this solution (A) is mixed with a further aqueous solution (B) which contains N-methylmorpholine, a solution (C) being formed which
• N-methylmorpholine-N-oxide is formed in water, which is used in the amine oxide process.
• a peroxide is best used as the oxidizing agent.
• the aqueous solution (A) originating from the amine oxide process also contains morpholine in addition to N-methylmorpholine.
• This morpholine is a precursor of the toxic N-nitrosomorpholine in the course of oxidation.
• the inventors of the present invention have recognized that the formation of the Toxic N-nitrosomorpholine can be suppressed if the solution (C) to be treated with the oxidizing agent has a pH between 6.0 and 9.0. It has been shown that it is possible, simply by adjusting the pH of the oxidation mixture in the range mentioned, to suppress the formation of the toxic N-nitrosomorpholine and at the same time to achieve a maximum of oxidation of N-methylmorpholine to NMMO.
• the pH dependence of these two reaction routes can be seen in the attached figures and is described in the applicant's Austrian patent application A 1398/95.
• the cation exchanger best has carboxyl groups or sulfonic acid groups for the separation of morpholine.
• N-nitrosomorpholine which are formed despite the above-mentioned pH adjustment, can be largely destroyed by the aqueous solution (C) being irradiated with ultraviolet light during or after treatment with the peroxidic oxidizing agent essentially has a wavelength of 254 nm.
• the presence of the peroxidic oxidizing agent is impaired not this destruction.
• the destruction of N-nitrosomorpholine with ultraviolet light is described in Austrian patent application A 1401/95.
• H-O- is preferably used as the peroxidic oxidizing agent in the process according to the invention.
• This H 0 is preferably used in the form of an aqueous solution with 20-50 wt .-% H_0.
• the H 0 is best used in an amount of 0.8 to 2 moles per mole of N-methylmorpholine.
• the ultraviolet light with which the aqueous solution is irradiated comes best from a low-pressure mercury lamp. These low pressure lamps have an intensity maximum at 254 nm.
• the lamp can be suspended in the container which contains the process water to be treated.
• the lamp can also be arranged in a different way.
• the irradiation can also be carried out, for example, while the solution to be irradiated is continuously pumped around in a thin-film UV reactor.
• the radiation power can be, for example, 200 to 500 ⁇ -J / cm 2 and is dependent on the design of the lamp and on the process conditions, in particular the temperature. Also this embodiment of the method according to the invention does not require any additional chemicals.
• solution (D) In order to remove unreacted N-methylmorpholine, which is still contained in the solution (D), it has proven to be expedient to subject the solution (D) to distillation. This produces vapors which, after condensation, result in a solution (E) which can at least partially be used as solution (B).
• the invention further relates to a process for the production of cellulosic moldings by the amine oxide process, in which cellulose is dissolved in an aqueous NMMO solution to form a moldable solution, the solution obtained is shaped and, after molding, is passed into a precipitation bath, cellulosic moldings and a used precipitation bath are formed, which precipitation bath is worked up to recover NMMO, an aqueous solution is obtained which contains N-methylmorpholine and which, optionally together with vapor condensates formed in the amine oxide process, is subjected to oxidation to produce a new aqueous NMMO solution which is used again for the production of a moldable cellulose solution, which is characterized in that new N-methylmorpholine-containing solution obtained in the working up of the used precipitation bath is added, whereupon the solution is subjected to the oxidation.
• N-methylmorpholine is fed to the amine oxide process and together with that N-methylmorpholine, which is produced in the amine oxide process by degradation of NMMO and in the various process liquids, such as vapor condensates, which are used in the preparation of the moldable cellulose solution or accumulate during evaporation of the precipitation bath, is oxidized to NMMO.
• the person skilled in the art is free to determine the point in time at which N-methylmorpholine is added to those from the amine oxide process choose process water without affecting the result of the process according to the invention.
• NMOR N-nitrosomorpholine
• N-methylmorpholine-N-oxide N-methylmorpholine
• morpholine morpholine
• a mixture of vapor condensates which are formed from the cellulose suspension in the preparation of the moldable cellulose solution and during the evaporation of the precipitation bath to be worked up and which contain NMMO and NMM, is filtered and concentrated in a reverse osmosis system.
• the retentate thus obtained contains, for example, about 7 kg of NMM and about 15 kg of NMMO per 1000 kg.
• This solution is mixed with 44.3 kg NMM per 1000 kg and introduced into a reactor for oxidation. 79.5 kg of 22% H 2 O 2 are added at 65 ° C. with stirring over 10 minutes. After a reaction time of 7 hours at 70 ° C., unreacted NMM is evaporated from the solution under reduced pressure of 100 mbar.
• An aqueous solution which contains 51.8 kg of NMMO dissolved and remains in the amine oxide process i.e. can be used to prepare the cellulose suspension.
• the condensate obtained during evaporation contains unreacted NMM (19.5 kg) and is mixed with 24.8 kg NMM and added to the next batch of retentate.
• Example 2 A mixture of vapor condensates, which are formed from the cellulose suspension in the preparation of the moldable cellulose solution and during the evaporation of the precipitation bath to be worked up and which contain NMMO and NMM, is filtered and concentrated on in a reverse osmosis system.
• the retentate thus obtained contains, for example, about 7 kg of NMM and about 15 kg of NMMO per 1000 kg.
• This solution is mixed with 44.3 kg NMM per 1000 kg and then cleaned using a cation exchanger.
• the cleaned solution is placed in a reactor for oxidation.
• the addition of 79.5 kg 22% H 2 0 2 is carried out.
• reaction time at 70 * C the solution is transferred to an additional container and irradiated for 10 hours by ultraviolet light having a wavelength of 254 nm. Unreacted NMM under reduced pressure of about 100 mbar and a temperature of 70 * C is then evaporated from the solution.
• the condensate obtained during evaporation contains unreacted NMM (19.5 kg) and is mixed with 24.8 kg NMM and added to the next batch of retentate.
• aqueous solution containing 42 ⁇ .q NMOR, 459 mg NMMO, 4300 mg NMM and 200 mg M per liter was in a UV reactor with a low-pressure mercury lamp (type Katadyn UV lamp EK-36, No. 79000 ; Manufacturer: Katadyn) irradiated (wavelength: 254 nm).
• the temperature of the aqueous solution was 60 * C.
• the NMOR content in the process water decreased to 40 ⁇ g / l. After a further 150 minutes no NMOR was detectable.
• the NMOR concentration rose to 45 ⁇ g / l, which is due to a quick reaction of the M in the solution. Then the concentration of NMOR decreased again sharply. No NMOR was detectable after 6 hours.
• the solution contained 5386 mg NMMO / liter. This corresponds to a yield of 62% of theory.
• Figure 1 shows the pH value as the abscissa and the yield of NMMO formed (% of theory) as the ordinate. It can clearly be seen that there is a maximum of approximately 50% in the range between 6.0 and 9.0.
• Fig. 2 the pH value is also given as the abscissa and the concentration (in ppb) of NMOR in the solution after oxidation is given as the ordinate. It can be seen that the formation of the N-nitrosomorpholine only increases sharply from a pH of 8-9. In the range between 6.0 and 9.0, the formation of NMMO is thus maximized and, at the same time, the formation of the toxic N-nitrosomorpholine is minimized. This applies in particular to the pH range between 7.0 and 9.0.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Textile Engineering (AREA)
• Biochemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Materials Engineering (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Citations (4)

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• 1996
  • 1996-07-02 AT AT0116596A patent/AT404033B/de not_active IP Right Cessation
• 1997
  • 1997-07-01 JP JP10503662A patent/JPH11511764A/ja active Pending
  • 1997-07-01 WO PCT/AT1997/000147 patent/WO1998000589A1/de not_active Application Discontinuation
  • 1997-07-01 CA CA002230050A patent/CA2230050A1/en not_active Abandoned
  • 1997-07-01 CN CN97190801A patent/CN1196762A/zh active Pending
  • 1997-07-01 ID IDP972286A patent/ID17544A/id unknown
  • 1997-07-01 EP EP97929010A patent/EP0874927A1/de not_active Withdrawn
  • 1997-07-01 BR BR9706559A patent/BR9706559A/pt not_active Application Discontinuation
  • 1997-07-01 AU AU33278/97A patent/AU3327897A/en not_active Abandoned
• 1998
  • 1998-01-28 NO NO980371A patent/NO980371L/no unknown

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