Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P5/00—Other features in dyeing or printing textiles, or dyeing leather, furs, or solid macromolecular substances in any form
  • D06P5/20—Physical treatments affecting dyeing, e.g. ultrasonic or electric
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P1/00—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed
  • D06P1/22—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed using vat dyestuffs including indigo
  • D06P1/221—Reducing systems; Reducing catalysts
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P1/00—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed
  • D06P1/30—General processes of dyeing or printing textiles, or general processes of dyeing leather, furs, or solid macromolecular substances in any form, classified according to the dyes, pigments, or auxiliary substances employed using sulfur dyes
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06P—DYEING OR PRINTING TEXTILES; DYEING LEATHER, FURS OR SOLID MACROMOLECULAR SUBSTANCES IN ANY FORM
  • D06P5/00—Other features in dyeing or printing textiles, or dyeing leather, furs, or solid macromolecular substances in any form
  • D06P5/20—Physical treatments affecting dyeing, e.g. ultrasonic or electric
  • D06P5/2016—Application of electric energy

Definitions

• the present invention relates to a method for the electrochemical reduction of vat and sulfur dyes in aqueous solutions according to claim 1 and an apparatus for carrying out this method according to claim 11.
• vat and sulfur dyes to cellulosic materials takes place in the reduced form, since only this is water-soluble and has a high affinity for substrates.
• the dye is converted from its leuco form back into the water-insoluble pigment structure.
• vat and sulfur dyes for printing and dyeing cellulosic fibers has hitherto been linked to the use of overstoichiometric amounts of reducing agent (based on the amount of dye to be reduced).
• the vat dyes are usually reduced in alkaline (pH> 9), aqueous solutions with sodium dithionite (hydrosulfite) or reducing agents derived therefrom (RONGALIT C, BASF) in conjunction with wetting agents and complexing agents.
• Other reducing agents such as thiourea dioxide or endiolates, have barely become established for price reasons, and in the case of thiourea dioxide there is an environmental problem similar to that of hydrosulfite.
• the reducing agents suitable for reducing the vat dyes show a redox potential of -400 mV to -1 O00 mV under the conditions necessary for the vatting of the dyes.
• Both the use of hydrosulfite and thiourea dioxide lead to a high sulfite or sulfate load in the waste water. These salt loads are both toxic and corrosive and lead to the destruction of concrete pipes.
• Another problem with the sulfate load in the wastewater resulting from the sulfite is the formation of hydrogen sulfide caused by anaerobic organisms in the sewer pipes.
• redox mediator systems such as, for example, iron (II) or iron (III) complexes (T. Bechtold et. Al., Angew. Chem. Int. Ed. Engl. 1992, 31, No. 8, 1068-9; WO 90/15182).
• the reducing agent or mediator used is the dye-reducing agent.
• the mediator system is electrochemically, according to the example mentioned above (eg Fe 2+ ⁇ --> Fe 3+ ) regenerated cathodically. Due to the high amounts used and the ecological concern of such mediators, there is still an acute environmental problem that can only be solved by additional investments in adequate wastewater technology or by a recycling process. Another disadvantage of these processes is the permanent addition of mediators to maintain the redox cycle in continuous dyeing. The subsequent dosing of the mediator system results from the liquor discharge proportional to the fabric or yarn flow.
• the object is achieved by a method according to claim 1 and an apparatus according to claim 1 1.
• FIG. 1 Schematic representation of the electrochemical veining
• FIG. 2 Schematic representation of an apparatus for continuous, electrochemical dye reduction
• Vat dyes for the purposes of the present invention include, in addition to the indigoid dyes, with indigo itself being preferred, also to understand anthraquinone dyes and, if appropriate, also non-pre-reduced sulfur dyes.
• the dye A reacts with the reduced dye species P, hereinafter briefly referred to as species P, which represents the leuco form of the dye A, in a proportioning reaction (I) in which two dye radical anions 2R are formed.
• Comproportionation is a reaction in which a higher and a lower oxidation level of an element or a chemical compound come together to form a medium one (G. Ackermann, et al., Electrolyte Balances and Electrochemistry, Chemistry Study Volume 5, p. 188 ( 1974), Verlag Chemie, Weinheim; Römpp, Lexikon Chemie, 10th edition, Thieme Verlag, p. 2223 (1997)).
• the two dye radical anions 2R which are water-soluble due to their charge, are electrochemically measured according to reaction equation (II) at the cathode to form the dianions, respectively. reduced the species 2P.
• reaction equation (II) reaction equation (II)
• a DC voltage adapted to the redox potential of the dye radical anions 2R is applied to the existing electrodes.
• Fig. 1 shows a schematic representation of the electrochemical vein just described.
• the steady state reaction conditions are achieved by various start reactions, which will be described later.
• the dye is reduced in an oxygen-free electrolysis vessel, which contains both the electrodes and any mixing unit.
• Various cell connections allow continuous and batch operation of the electrolysis equipment.
• the dye pigment A is introduced into the electrolysis vessel in an aqueous suspension containing various additives.
• the alkaline pH required for dye reduction is 10.5 - 13, which is adjusted with alkali metal hydroxide, especially sodium hydroxide solutions.
• tensides, reducing agents and solvents are used as additives in low concentrations.
• the additives used can be discontinued or their concentration changed after the start of the reaction.
• the starting reactions that lead to the steady state reaction conditions are described in the following using reaction equations (IIIA) - (MIC).
• reaction equation (IIIA) shows a first start reaction:
• reaction starter used is a commercially available reducing agent B, suitable for reducing vat dyes, such as Hydrosulfite or an endiolate used in a substoichiometric ratio with respect to dye A.
• the reducing agent B reduces an amount of dye A corresponding to its use amount to the species P or to the dianion.
• the method according to the invention thus differs significantly from a reaction procedure which uses a mediator system which must be present in an imperative manner at all times.
• Hydrosulfite and its derivatives e.g. Formaldehyde sulfoxylate (RONGALIT C, BASF)
• ⁇ -hydroxy ketones e.g. Monohydroxyacetone, dihydroxyacetone,
• ⁇ -hydroxyaldehydes such as glycol aldehyde, triose reductone (2,3-dihydroxyacrylic aldehyde) or
• reaction equations (MB) show a second starting reaction
• auxiliaries X dye-affine solubilizing or dispersing agents
• the dye A or the dye pigment, forms a solubilized complex (AX) sol (IIIB.1) with these auxiliaries, which is reduced electrochemically to the species P (IIIB.2).
• the auxiliaries thus enable a direct electrochemical reduction of the microdisperse color pigment, the behavior of which is similar to that of a dissolved compound due to the solubilization.
• excipients X respectively.
• the following compounds are used as dye-affine solubilizing or dispersing aids-
• Ketones such as N-methylpyrrodon, 4-hydroxy-4-methylpentanone-2 (diacetone alcohol),
• Alcohols e.g. Methanol, ethanol, iso-propanol, with methanol and iso-propanol being particularly preferred,
• Acetals e.g. Glycol formal and glycerin formal
• glycol ethers such as, for example, propylene glycol, ethylene glycol monomethyl, ethyl or butyl ether, diethylene glycol monomethyl or ethyl ether,
• Pyrids e.g. Py ⁇ din and ⁇ -, ß- and ⁇ -picolme
• Lactams such as pyrrohdon, N-methylpyrrohdon and 1,5-dimethylpyrrolidone
• Acids and acid amides such as, for example, benzenesulfonic acids,
• Naphthalenesulfonic acid derivatives such as e.g. Setamol WS (naphthalene sulfonate condensed with formaldehyde),
• auxiliaries are used in amounts of approximately 1 to 90%, preferably 5 to 30%, based on the dye composition used.
• the use of ultrasound as a dispersing aid has proven itself to support the solubilization or dispersion by the auxiliaries described.
• the suspension is exposed to ultrasonic energy during or before the reduction of the dye.
• reaction equations (MC) show a third start reaction:
• a radical starter S is activated under the influence of physical means, such as UV radiation, cobalt radiation and / or ultrasound, whereby it is converted into an excited state S * of the radical starter (IIIC.1). This reacts with the dye A, from which a radical anion R is formed (MC.2). This provides the conditions for the stationary cycle to start with reaction equations (I) and (II).
• radical initiators Benzophenones, its diaryl ketone derivatives, anthraquinones and xanthones are used as radical initiators.
• Further classes of compounds suitable as radical initiators are azo compounds and diazonium salts (e.g. azo-isobutyronitrile).
• UV burners or any radiation sources, including harder radiation, and ultrasound can be used in a known manner.
• the ultrasonic waves that are used according to the method are generated with conventional ultrasonic generators. Their frequency is in the range of 16 kHz and above, preferably 20 to 30 kHz.
• the ultrasound energy to be used depends on the dye or the radical-forming substance and the size of the reaction vessel. Power between 0.5 and 1 kW is usually used to generate the cavitation required for radical formation in the reaction medium.
• Combinations of reduction starters with solubilizing or dispersing agents show synergistic effects in such a way that the reaction rate to be achieved in the starting phase is greater than that with the reduction starter or with the Solubilizing or dispersing agents alone With increasing reaction conversion, the reaction rate increases due to the superimposition of the comproportionation reaction and the previously described reaction sequence with the solubilizing or dispersing aids used.
• Preferred combinations for starting the reaction are sodium hydrosulfite as starter and certain naphthalenesulfonic acids (Setamol WS from the company BASF Ludwigshafen) or their combinations as dispersants.
• ionic or non-ionic surfactants and protic and aprotic solvents are also used as additives according to the invention, which have both dye and electrode affinity and do not themselves have a reducing effect.
• Typical representatives of these substances are alcohol propoxylates such as e.g. Lavotan SFJ, alcohol sulfates such as e.g. Sandopan WT, Subitol MLF and alkyl sulfonates such as Levapon ML.
• the amounts used of these additives are in the range from 0.1 to 10 g / l, preferred concentrations are between 1 and 5 g / l.
• the method according to the invention achieves surprising advantages in the field of dyeing cellulosic materials with vat dyes, in particular indigo.
• This tying technique also leads to largely salt-free dyeing, which automatically ensures higher reproducibility and better fabric or yarn quality. Further advantages are the high stability of the reduced stem vat fleet in the oxygen-free electrolysis vessel, the high dye solubility of the linked species, the continuous dye reduction and thus the "just in time" preparation of the dye solution.
• This reduction technique is suitable for both color master batches and dyeing liquors.
• the enormous economic advantage lies in the reduction in the consumption of chemicals (reducing agents and sodium hydroxide solution), the production of a better quality product and significantly lower wastewater costs due to the existing biocompatibility of the remaining wastewater constituents. There are no toxic loads on the waste water side, which makes it possible to recycle the waste water with significantly lower expenditure compared to conventional dyeing systems.
• Electrode material which are stable in the alkaline range (pH 9 to 14) and which have no hydrogen formation with the redox potential required for dye reduction can be used as the electrode material.
• This also includes electrodes that have been modified by special surface treatments. This can be done by adsorbing special surfactants with a typical HLB value (hydrophilic / hydrophobic balance) of 8 to 14 or by partial coating with a hydrophobic polymer suspension. Typical substances are polytetrafluoroethylene, tetrafluoroethylene oligomers and polystyrene.
• the size of the electrode surface is determined by the required coupling power and is designed specifically for the reactor.
• the voltage applied to the electrodes is a function of the coupling potential of the dye (taking into account the comproportionation reaction) and also depends on the nature of the electrodes. Usually voltages from 2.3 V to 2.6 V are applied.
• Fig. 2 shows an apparatus for continuous, electrochemical dye reduction in a schematic representation.
• An electrolysis vessel 1 with a lid 1 ', tightly closed by means of seals 2, is part of a circuit with the line 13, with a pump P1, a line 13', a steel tube spiral 3, a line 13 "and an inlet tube 4, which extends over the lid 1 'leads back into the electrolysis vessel 1.
• the steel tube spiral 3 is located on an ultrasound transducer 5.
• the energy input via the ultrasound transducer 5 is 100-1000 watts and is used for radical formation and dye dispersion.
• the dye suspension in the electrolysis vessel 1 with the alkali and that of The selected start reaction-dependent additives are circulated in a circulation flow V1 'by means of the pump P1 during the entire coupling time, the steel tube spiral 3 with the ultrasonic vibrator 5 acting as a dispersing aid.
• the electrolysis vessel 1 there is also a pair of electrodes 6, 6 'to which an electrical voltage of approximately 2.2 V is applied after the start reaction is complete.
• the same as the originally submitted dye suspension is introduced from a second vessel 11 with a lid 11 'by means of a pump P2 in a volume flow V2' via lines 14, 14 'into line 13 and thus supplied to the circulation stream V1'.
• a volume flow V3 'corresponding to the volume flow V2' is taken from the electrolysis vessel 1 and metered by means of a pump P3 via lines 15, 15 'and an inlet pipe 16 into an oxygen-free storage vessel 21 which is sealed with a lid 21' and seals 22 is.
• the reducing agent-free, electrochemical dye coupling carried out in this way corresponds to the principles of continuous reaction control in an ideal mixed stirred kettle.
• a complete exchange (> 99.9%) of the reaction volume is achieved after 6 ⁇ .
• Example 1 describes an electrochemical batch linkage with a reducing agent B according to the start reaction (IIIA).
• a coloring solution with a dye concentration of 5 g / l is prepared with 20 ml of this stock vial.
• the dyeing is carried out in the absence of oxygen using 10 g of cotton fabric at a temperature of 30 ° C. for 10 minutes.
• the sample is oxidized in air, rinsed and finally washed at 50 ° C.
• the pattern thus produced shows a brilliant shade of blue, the color depth is identical to j enigen a color pattern manufactured according to the conventional color method with sodium hydrosulfite.
• Example 2 describes a first continuous electrochemical vatting according to the start reactions (MB) with solubilization and dispersion aids.
• the electrochemical coupling is carried out in an apparatus according to FIG. 2.
• 5 g of indigo are dispersed in 100 ml of water which simultaneously contains 3 5 g of sodium hydroxide solution and 2 g of Setamol SW as a dispersant.
• the dye suspension is dissolved in an oxygen-free, stirred, thermostated to 40 ° C. and given electrolysis vessel 1 equipped with electrodes 6, 6 '.
• the dye suspension is pumped with a circulation flow V1 'of 20 ml / min during the entire coupling time.
• the working voltage applied to the electrodes is 2.0 V with a current flow of 2.0 A. After approx. 40 minutes, under the specified conditions, the electrolysis vessel results in a 100% reduced color loss.
• the power entered via the ultrasonic vibrator 5 is approximately 150 watts and is used for radical formation and dye dispersion.
• a 5% indigo suspension is then conveyed from the second vessel 11 into the circulation flow V1 'by means of the pump P2 with a volume flow V2' of 15 ml / mm.
• the indigo suspension located in the storage vessel 11 has the same composition as described at the beginning.
• a volume flow V3 'of 1.5 ml / min corresponding to the paint flow V2' is removed from the electrolysis vessel 1 and metered into the oxygen-free storage vessel 21 by means of the pump P3
• Example 3 describes a second continuous electrochemical linking of indigo with the aid of solubilization or dispersion aids in accordance with the starting reactions (MB).
• indigo 5 g of indigo are dispersed in 100 ml of water, into which 2 g of Setamol WS and 5 ml of methanol have previously been added.
• 3 g of sodium hydroxide solution are added to the suspension, which is then added to the nitrogen-purged and stirred electrolysis vessel.
• the heatable electrolysis vessel is thermostatted to 35 ° C. After reaching the temperature (35 ° C) the current is switched on (2.2 V, 2.0 A) for electrochemical dye coupling.
• the continuous process is started.
• a suspension (without methanol) containing Setamol WS (3 g / l) and indigo (50 g / l) is fed in at a volume flow of 1.5 ml / min in the electrolysis vessel.
• the volume flow discharged from the vessel is also 1.5 ml / min and contains the dye, which is reduced by over 95%.
• the Setamol WS supplied in continuous operation leads to a synergistic effect in the process described above, which is reflected in an increased reaction speed.
• Example 4 describes an electrochemical coupling with a photochemical start reaction in accordance with the start reactions (MC).
• 5 g of indigo are dispersed in 200 ml of water, which contains 2 g of sodium hydroxide solution and 10 ml of methanol, using ultrasound. Then 0.5 g of Michler's ketone [4,4-bis (N, N-dimethylamino) benzophenone] is added to the dye suspension as a radical initiator. The reaction mixture is purged into a nitrogen to 30
• the UV burner is switched off and continuous linking is started, which is carried out exclusively electrochemically.
• a dye volume flow of 1 ml / min of a dye suspension with 25 g / l indigo and 3 g / l caustic soda (without radical starter and methanol) is fed to the electrolysis vessel and at the same time a volume flow of 1 ml / min is removed from the electrolysis vessel.
• the reaction vessel is operated as an ideally mixed stirred tank, with which a degree of vatage of> 95% was determined under the given conditions in the reactor outflow.
• vat stock solution which is continuously produced in this way, only contains dye and sodium hydroxide solution, since the radical initiator and the methanol initially used are completely discharged after approx. 6 ⁇ and the dye is reduced directly without any additional auxiliaries.
• the reduction starters or auxiliary substances necessary for the start of the reaction should only be used in low concentrations.
• the reduction starters or auxiliaries required for the start phase and their quantities can be optimally adapted to the desired conditions (reaction speed, costs, etc.).

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Coloring (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
• Treating Waste Gases (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1999
  • 1999-11-24 WO PCT/CH1999/000562 patent/WO2000031334A2/fr not_active Ceased
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  • 1999-11-24 CA CA002318796A patent/CA2318796A1/fr not_active Abandoned
  • 1999-11-24 AU AU11465/00A patent/AU1146500A/en not_active Abandoned
  • 1999-11-24 DE DE59912528T patent/DE59912528D1/de not_active Expired - Fee Related
  • 1999-11-24 EP EP99972704A patent/EP1056900B1/fr not_active Expired - Lifetime
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