摘要:
The disclosure pertains to an electrochemical reactor (1), in particular but not exclusively for vatting sulphur dye or vat dye as well as to methods of using such a reactor and to uses of such a reactor. The electrochemical reactor comprises at least one liquid compartment (3) in which a multitude of freely suspended granules (14) is enclosed, wherein at least one of the side walls (5) of the compartment is an electrode and an opposite side wall is formed by a separator element (6), typically a membrane, wherein there is provided a bottom inlet (7,9) and a top outlet (8,10) of the compartment for a liquid catholyte (9) or a liquid anolyte (7), wherein the inlet region as well as the outlet region of the compartment are provided with an upper grid (11') and a lower grid (11''), the width of the mesh and the positioning of which is chosen such as to allow the liquid catholyte or the liquid anolyte to pass through from bottom to top but to prevent the granules to pass through the grids to leave the compartment, and wherein the upstream flow of the liquid catholyte or of the liquid anolyte can be adjusted so that in operation the multitude of granules is dragged against the upper grid while the lower grid is substantially not in contact with the granules.
摘要:
Leuco vat dye preparations in granular form, containing as their essential components leuco vat dyes, alkaline metal hydroxide and a mixture of 10 to 100 wt.% of an α-hydroxy-C1-C4-alkyl sulphinic aid, one of its salts or derivatives and 0 to 90 wt.% of hydrosulphite as a reducing agent, and the production of these preparations and their use in dyeing cellulose-containing fabrics.
摘要:
A process is disclosed for reducing textile dyestuffs in an aqueous alkaline medium by means of a complex containing an iron salt. For that purpose, a quantity of iron (II) salt is used that is sufficient to ensure the desired reduction of the dydstuff after a single oxidation.
摘要:
The invention relates to mediator systems that are obtained by mixing a salt of a electrochemically active complex-forming metal (M1) that can form different valency states with a hydroxy-group containing complexing agent that may also be present as a salt, and a salt of an electrochemically inactive, likewise complex-forming metal (M2) in an alkaline aqueous medium. The molar ratio of the metal ion M2 to the metal ion M1 is 0.8:1 to 2:1. The invention further relates to a method for reducing dyes and for dyeing cellulose-containing textile materials using said mediator systems.
摘要:
The invention relates to a method for the electrochemical reduction of vat or sulphur dyes, by bringing the dye (1) into contact with a modified cathode (2), comprising a support (3) made from an electrically-conducting material with a large surface area on which a redox-active substance (4) is permanently immobilised. Substances with quinoid structures, in particular, an anthraquinoid structure are preferably applied in the above. No toxic contamination and greatly reduced salt loads in the effluent are achieved by means of the above method.
摘要:
The invention relates to a method for the electrochemical reduction of vat and sulfur dyes in aqueous solutions, in steady-state conditions of reaction and a cycle which is largely free of reducing agents. The invention also relates to apparatus for carrying out said method. The steady-state conditions of reaction are obtained by means of a start reaction. The substances used for this reaction and the products resulting therefrom are extracted from the cycle. To maintain the cycle only dyes, an alkali and possibly small quantities of additional substances, such as surface-active agents, need to be added. No other chemicals active in the oxidation-reduction process are used.
摘要:
A method is provided for dyeing a non-cellulosic organic material with a dye, preferably a vat dye, comprising (a) treating the material with a dye in the presence of a reducing agent and an alkali and (b) oxidising the treated material produced in step (a) characterised in that the concentration of reducing agent used in step (a) is increased above that used for conventional vat dyeing such that the resultant dyed material has a lightfastness of 5 or more by BS1006 B01 and B02 (1978) and/or has a washfastness or 5 or more by British Standard Test BS1006 C06.C2 (1981). Preferably the step (a) is carried out in the presence of an alkali in concentration of at least 0.5 molar, more preferably 1 molar or more and most preferably 1 to 4 molar. The method provides vat dyed non-cellulosic organic materials having a reflectance of infrared light of wavelength 400nm to 680nm of less than 15 %.