DYEING PROCESS WITH SULFUR DYES

Abstract: A process for dyeing polyamide or polyamide-containing substrates with sulfur dyes comprises effecting said dyeing in a pH range of 8 - 11 and at 90 - 120 DEG C and with reducing agents which are suitable under these conditioners. Also claimed are substrates dyed using this process.

Description: Dyeing Process with Sulfur Dyes This invention comprises a process for dyeing polyamide substrates or polyamide-containing substrates with sulfur dyes and substrates dyed with such a dye. Sulfur dyes are an important class of dyes. This class is extensively described in Venkatamaran "The Chemistry of Synthetic Dyes", volume II (chapters XXXV and XXXVI) (1952) and volume VII (1974) and in the Colour Index. Essentially they are dyes which contain aromatically attached oligo sulfur linkages which are reducible to thiol groups and which may be of oligomeric or polymeric structure. They are mainly obtained by thionation of the respective intermediates at high temperature, for example above 100°C, especially in the temperature range from 1 10 to 300°C (eg by baking or in the melt or in the presence of water and/or an inert organic solvent). The exact structure of sulfur dyes is generally unknown or incompletely known, even though the starting materials are known, since, for example, the number or position of the oligo sulfur linkages, the number of sulfur atoms in an oligo sulfur linkage, the number of hetero rings and/or NH linkages and/or the number of structural repeat units in the sulfur dye molecule may vary according to starting materials and synthetic conditions. Sulfur dyes are most prominently used in cellulose dyeing. The most widely used sulfur dye of this category is C.I. Sulfur Black 1 , which is based on the organic compound I. Other sulfur dyes include CI. Sulfur Black 2, CI. Sulfur Black 1 1 , CI. Sulfur Black 18, CI. Sulfur Green 35, etc. A detailed list may be found in the Colour Index. As mentioned above, sulfur dyes are used in particular to dye cellulose or cellulose- containing fabric. The most widely used process for dyeing these materials is the exhaust and continuous process. Sulfur dyes are preferably used in aqueous form, especially in the form of an aqueous paste. The aqueous form may be prepared, for example, by suspending a commercially available sulfur dye, or a sulfur dye prepared by baking or in the melt, in water. Sulfur dyes are applied to the substrates in the reduced (leuco) form and are then oxidized. That is, sulfur dyes may be added to the dyeing liquor in the reduced form or in the oxidized form, which is then reduced using a suitable reducing agent. It is customary to use the reducing agent in excess to ensure that the dyes are indeed present in the reduced form, since atmospheric oxygen, for example, can oxidize sulfur dyes. Useful reducing agents are .all reducing agents known as suitable in the prior art, especially sodium hydrosulfide, sodium formaldehydesulfoxylate, potassium formaldehydesulfoxylate, zinc formaldehydesulfoxylate, thiourea, polysulfides (Na x S y ), sodium sulfide, hydroxyacetone and glucose. Useful oxidizing agents include all oxidizing agents known as suitable in the prior art, especially bichromates (K 2 Cr0 7 . Na 2 CrO ), bromates (NaBr0 3 , NaI0 3 ), bromites (NaBr0 2 ), perborates ( aB0 3 ), persulfates ( 2 S 2 0 8 , Na 2 S 2 O 8 ), hydrogen peroxide and chlorates (NaClO 3 ). Polyamide substrates and polyamide-containing substrates have hitherto not been satisfactorily dyeable with certain sulfur dyes, for example C.I. Sulfur Black 1 or CI. Sulfur Black 2. For instance polyamide/cotton blends were not dyeable on-tone with just one dye. The present invention, then, allows polyamide substrates or polyamide-containing substrates, for example polyamide/Lycra ® , polyamide/cotton, polyamide/cotton/Lycra ® (Lycra ® is a trademark of DuPont), polyamide/cotton, etc, to be dyed with Sulfur Black 1, Sulfur Black 2 or Sulfur Green 16 in good fastnesses. Polyamide microfibers, for example Meryl ® (Meryl ® is a trademark of Nylstar) are likewise suitable for dyeing according to the invention. A further advantage of the process according to the invention is that good on-tone dyeing is obtained with just one dye and a one-step dyeing process, for example on a cotton/polyamide substrate, and this is something previously known processes did not provide. In the prior art, polyamides and polyamide-containing substrates are dyed with individual sulfur dyes at up to 95°C and a pH of 12 - 14. The invention provides a process for dyeing polyamides or polyamide-containing substrates with sulfur dyes and/or mixtures thereof, which comprises effecting said dyeing in a pH range of 7.5 - 1 1, especially 8 - 1 1, and at 60 - 120°C, especially 90 - 120°C The sulfur dyes used may be used not only in reduced form but also in oxidized form. Preference is given to a process of the invention wherein CI. Sulfur Black 1, CI. Sulfur Black 2, CI. Sulfur Green 16 and/or mixtures thereof are used as sulfur dye. Particular preference is given to a process of the invention wherein CI. Sulfur Black 1 is used as sulfur dye. Preference is likewise given to a process of the invention wherein the dyeing is effected at 60 - 1 10°C, especially 90 - 1 10°C, more preferably at 95°C, likewise more preferably at 1 10°C Preference is given to a process of the invention wherein the dyeing is effected at a pH of 9.5 - 11. Preference is given to a process of the invention wherein sodium formaldehydesulfoxylate, potassium formaldehydesulfoxylate, zinc formaldehydesulfoxylate and/or mixtures thereof are used as reducing agent. The invention likewise provides a process wherein wetting agents, lubricants, sequestrants and or antifoams are added. The invention further provides a polyamide or polyamide-containing substrate dyed by a process according to the invention. The process of the invention is particularly suitably carried out using dyes of the Diresul ® EV type. (Diresul ® is a trademark of Clariant). . The examples hereinbelow illustrate the invention. Percentages are by weight, unless otherwise stated. Temperatures are in degrees Celsius. The liquor ratio used in the examples hereinbelow is always 10: 1 , unless otherwise stated. Example 1: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (C.I. Sulfur Black 1 ) (manufactured by Clariant), 5g/l of sodium formaldehydesulfoxylate, 3g/l of calcined sodium carbonate and l ml/1 of a wetting agent. The polyamide microfiber (Meryl ® ) is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 1 10°C at 2°C/min. Dyeing continues at 1 10°C and pH 9 - 10.5 for 30 minutes, and the bath is then cooled down to 70°C at 2°C/min. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has very good fastnesses. Example 2: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (C.I. Sulfur Black 1 ) (manufactured by Clariant), 5 g/1 of sodium formaldehydesulfoxylate, 1 g/1 of calcined sodium carbonate and 1 ml/1 of a wetting agent. The polyamide microfiber (Meryl ® ) is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 1 10°C at 2°C/min. Dyeing continues at 1 10°C and pH 9 - 10.5 for 30 minutes, and the bath is then cooled down to 70°C at 2°C/min. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has good fastnesses. Example 3: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (C.I. Sulfur Black 1 ) (manufactured by Clariant), 3 g/1 of calcined sodium carbonate, l ml/1 of a wetting agent and 5g/l of sodium formaldehydesulfoxylate. The polyamide substrate (PA 6.6 Nylsuisse Art.2044) is introduced into the dyeing liquor at 60°C. The dyeing liquor is then heated to 95°C at 2°C/min. Dyeing continues at 95°C for 60 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has good fastnesses. Example 4: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (C.I. Sulfur Black I ) (manufactured by Clariant), 1 g/1 of calcined sodium carbonate, 1 ml/1 of a wetting agent and 5g/l of sodium formaldehydesulfoxylate. The polyamide substrate (PA 6.6 Nylsuisse Art.2044) is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 95°C at 2°C/min. Dyeing continues at 95°C for 60 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has good fastnesses. Example 5: The aqueous dyeing liquor is made up of 15% of Diresul ® Olive RDT-B liq. (C.I. Sulfur Green 16) (manufactured by Clariant), 3 g/1 of calcined sodium carbonate, lml/1 of a wetting agent and 5g/l of sodium formaldehydesulfoxylate. The polyamide substrate (PA 6.6 Nylsuisse Art.2044) is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 95°C at 2°C/min. Dyeing continues at 95°C for 60 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has good fastnesses. Example 6: The aqueous dyeing liquor is made up of 20% of Diresul ® Black EV-PL (C.I. Sulfur Black 2) (manufactured by Clariant), 3g/l of calcined sodium carbonate, 1 ml/1 of a wetting agent and introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 1 10°C at 2°C/min. Dyeing continues at 1 10°C for 30 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has good fastnesses. Example 7: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (C.I. Sulfur Black 1 ) (manufactured by Clariant), 3g/l of calcined sodium carbonate, lml/1 of a wetting agent and 5g/l of sodium formaldehydesulfoxylate. The polyamide/Lycra (80:20) blend substrate is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 95°C at 2°C/min. Dyeing continues at 95°C for 60 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has good fastnesses. Example 8: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (C.I. Sulfur Black 1 ) (manufactured by Clariant), 20g l of calcined Glauber salt, 3g/l of calcined sodium carbonate, lml/1 of a wetting agent and 5g/l of sodium formaldehydesulfoxylate. The polyamide/cotton/Lycra (30:60: 10) blend substrate is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 95°C at 2°C/min. Dyeing continues at 95°C for 60 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate shows excellent equalization in color strength and hue between the cotton and the polyamide and has commercially acceptable fastnesses. Example 9: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (CI. Sulfur Black 1 ) (manufactured by Clariant), 20g/l of calcined Glauber salt, 3g/l of calcined sodium carbonate, lml/1 of a wetting agent and 5 g/1 of sodium formaldehydesulfoxylate. The polyamide/cotton Lycra ® (30:60: 10) blend substrate is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 1 10°C at 2°C/min. Dyeing continues at 1 10°C for 60 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate shows excellent equalization in color strength and hue between the cotton and the polyamide and has commercially acceptable fastnesses. Example 10: The aqueous dyeing liquor is made up of 15% of Diresul ® Black EV-4G (C.I. Sulfur Black 1 ) (manufactured by Clariant), 3g/l of calcined sodium carbonate, l ml/1 of a wetting agent and 5 g/1 of sodium formaldehydesulfoxylate. The polyamide/Lycra ® (80:20) blend substrate is introduced into the dyeing liquor at 60°C The dyeing liquor is then heated to 95°C at 2°C/min. Dyeing continues at 95°C for 60 minutes, and the bath is then cooled down to 70°C at 2°C/min. The pH is between 9 and 10.5 during the dyeing process. The substrate is then rinsed with hot and cold water. The dye is oxidized on the substrate by using a sodium bromate solution (4g/l) at 70°C and a pH of 3 - 4, adjusted with acetic acid, for 30 minutes. The substrate is then rinsed with hot and cold water. The substrate has good fastnesses.

Claims: What is claimed is: 1 A process for dyeing polyamides or polyamide-containing substrates with sulfur dyes and or mixtures thereof, which comprises effecting said dyeing in a pH range of 7 5 - 1 1 and at 60 - 120°C 2 A process according to claim 1, wherein the sulfur dyes used are oxidized sulfur dyes which are reduced in the dyeing solution by a reducing agent which is suitable under the conditions indicated in claim 1 A process according to claim 1, wherein reduced sulfur dyes are used A process according to any one of claims 1 - 3, wherein C I Sulfur Black 1, C I Sulfur Black 2, C I Sulfur Green 16 and/or mixtures thereof are used as sulfur dye A process according to any one of claims 1 - 3, wherein C I Sulfur Black 1 is used as sulfur dye A process according to any one of claims 1 - 5, wherein said dyeing is effected at 90 - 1 10°C A process according to any one of claims 1 - 8, wherein said dyeing is effected at a pH of 9 5 - 1 1 A process according to any one of claims 2, 4, 5, 6 and 7, wherein sodium formaldehydesulfoxylate, potassium formaldehydesulfoxylate, zinc formaldehydesulfoxylate and/or mixtures thereof are used as reducing agent A process according to any one of claims 1 - 8, wherein wetting agents, lubricants, sequestrants and/or antifoams are added 0 A polyamide or polyamide-containing substrate dyed by a process according to any one of claims 1 - 9 AMENDED CLAIMS [received by the International Bureau on 24 November 2000 (24.1 1.00); original claims 1 and 4-10 replaced by amended claims 1 and 4-9; remaining claims unchanged (1 page)] 1. A process for dyeing polyamides or polyamide-containing substrates with CI. Sulfur Black 1 , CI. Sulfur Black 2, CI. Sulfur Green 16 and/or 5 mixtures thereof, which comprises effecting said dyeing in a pH range of 7.5 - 11 and at 60 - 120°C 2. A process according to claim 1, wherein the sulfur dyes used are oxidized sulfur dyes which are reduced in the dyeing solution by a reducing agent 10 which is suitable under the conditions indicated in claim 1. 3. A process according to claim 1 , wherein reduced sulfur dyes are used. 4. A process according to any one of claims 1 - 3, wherein CI. Sulfur Black 1 15 is used as sulfur dye. 5. A process according to any one of claims 1 - 4, wherein said dyeing is effected at 90 - 110°C 20 6. A process according to any one of claims 1 - 5, wherein said dyeing is effected at a pH of 9.5 - 11. 7. A process according to any one of claims 2, 4, 5 and 6, wherein sodium formaldehydesulfoxylate, potassium formaldehydesulfoxylate, zinc 25 formaldehydesulfoxylate and/or mixtures thereof are used as reducing agent. 8. A process according to any one of claims 1 - 7, wherein wetting agents, lubricants, sequestrants and/or antifoams are added. 30 9. A polyamide or polyamide-containing substrate dyed by a process according to any one of claims 1 - 8. SHEET ARTICLE 1ft

Inventors: ANNEN OSKAR, FURRER MARCOS, ANNEN, OSKAR, FURRER, MARCOS
Applicants: CLARIANT FINANCE BVI LTD, CLARIANT INT LTD, CLARIANT FINANCE (BVI) LIMITED, CLARIANT INTERNATIONAL LTD.
Application year: 2000
Main classification: D06P1
IPC codes: D06P1, D06P3