Bleaching and dyeing; fluid treatment and chemical modification – Reactive dye composition – process – or product – Alkylene sulfato – halotriazine – halodiazine,...
Reexamination Certificate
2000-07-31
2003-03-11
Gupta, Yogendra N. (Department: 1751)
Bleaching and dyeing; fluid treatment and chemical modification
Reactive dye composition, process, or product
Alkylene sulfato, halotriazine, halodiazine,...
C008S549000, C008S543000, C008S618000, C008S918000, C252S193000, C510S434000, C510S509000, C423S421000, C423S580100, C423S646000, C423S641000
Reexamination Certificate
active
06530961
ABSTRACT:
Cellulosic textile materials are dyed by printing, exhaust and padding processes. Fiber-reactive dyes, which are capable of entering a covalent bond with the fiber during the dyeing process, are particularly important dyes for cellulosics, since the dyeings obtainable therewith are notable for good wetfastnesses in particular, which is very difficult or impossible to achieve with non-fiber-reactive dyes. However, the covalent bond between the fiber-reactive dyes and the fiber generally only comes about when the dyeing process is carried out under alkaline conditions. The alkalis used are alkali metal carbonates, alkali metal bicarbonates and alkali metal hydroxides or mixtures thereof plus, in pad dyeing, alkali metal silicates, optionally together with an alkali metal hydroxide or carbonate, the term alkali metal including lithium as well as sodium and potassium. It is mixtures of alkali metal carbonates and alkali metal hydroxides in particular which are highly efficacious and are preferred, although the alkali system used in a particular case is chosen according to the specific fiber-reactive grouping of the dye and the specific dyeing process.
An ultrashort liquor dyeing process, for example the padding process, whereby the treatment liquor is applied to a textile material and the excess liquor on the textile material is then squeezed off, can be carried out according to both a one-stage and a two-stage procedure. The two-stage process procedures, whereby the textile material is initially impregnated with a dye solution to a certain wet pickup, then dried and subsequently overpadded in a further impregnating step with an alkaline electrolyte salt liquor, has the disadvantage of high machine usage and of utilizing electrolyte salts in the second process stage. In contrast, in a one-stage process, the complete treatment liquor, which contains both the fiber-reactive dye and the alkali with or without further auxiliaries, is applied to the textile material in one operation which is followed by the step of fixing the dye on the textile material.
One of these one-stage process procedures is the pad-cold batch process, which is chiefly used for dyes which contain a fiber-reactive group. In this case, the alkalinically binding agents used are frequently alkali metal silicates in the form of waterglass (Na
2
O: SiO
2
in a ratio of 1:2 to 1:3.5), between 60 and 130 g of waterglass of 38° Bé and 6 to 40 ml of approximately 32% strength by weight aqueous sodium hydroxide solution being added per liter of the dyeing liquor, depending on the target depth of shade. Waterglass has the advantage that it has a pH buffering effect and increases the stability of padding liquors of reactive dyes. Another positive effect of using waterglass in the padding process is that the edges of the material to be dyed will have the same depth of shade and hue, since waterglass forms a protective film against the carbon dioxide in the ambient air. Yet, the use of waterglass is not wholly beneficial. Examples of disadvantages are that waterglass tends to crystallize and thus tends to soil the equipment; that it is not possible to neutralize the textile material prior to the washing step; and that the use of steam for fixing the dyes is not always possible; moreover, unattractive hand effects may arise.
The literature describes attempts to remedy such disadvantages. For instance, in U.S. Pat. No. 4,555,348, an aqueous buffer system which has a pH between 11 and 13 and which contains various phosphate salts is added to dyeing liquors. Such an aqueous buffer system is undoubtedly suitable in dyebaths for exhaust processes, but not for dyeing by padding processes. Furthermore, the buffer system has the disadvantage that phosphate salts create environmental problems in water treatment plants.
The art of dyeing by the pad-cold batch process generally features the addition to the dyeing (padding) liquor of a specific amount of sodium hydroxide solution, decided on the basis of the amount of dye present in the padding liquor, and also of about 30 g/l of electrolyte salt, such as sodium chloride or sodium sulfate. However, padding liquor stability is generally unsatisfactory and leads to yield losses in the color strength of the dyeings.
However, the prior art also teaches that sodium carbonate alone or sodium hydroxide/sodium carbonate mixtures can be used in the case of highly fiber-reactive systems, for example dichloroquinoxaline, difluoromonochloropyrimidine and monofluorotriazine dyes. In the case of the pure sodium carbonate method, the lower pH will sometimes lead to uneconomically long fixing times, whereas the sodium hydroxide/sodium carbonate variant will sometimes bring about an increased reactive dye hydrolysis. These systems are less suitable for vinyl sulfone dyes, since the fixing time lengthens significantly and compromises the economics of the dyeing process. In addition, the art as it presents itself at present teaches in relation to the sodium hydroxide/sodium carbonate method that the amount of sodium hydroxide used varies with the dye concentration, while the sodium carbonate is always added as a fixed proportion.
It is an object of the present invention to provide, in the field of dyeing by ultrashort liquor processes, for example by padding processes, especially by the pad-cold batch process, an aqueous alkaline formulation which can be added to the dyeing liquor without creating the disadvantages mentioned.
It has now been found that, especially as replacement for waterglass in ultrashort liquor processes, such as padding processes, an aqueous solution comprising sodium hydroxide and potassium carbonate in a molar ratio of 1:1.7 to 1:0.5, preferably 1:1.5 to 1:1.1, particularly preferably 1:1.2 to 1:0.7, surprisingly has the desired advantageous effect. Moreover, the alkaline formulation of the invention has the particular advantage in use of being meterable. And the use of urea in the dyeing process can be dispensed with. Examples of formulations according to the invention which are suitable for production are aqueous solutions of 39.6 kg of sodium hydroxide and 110 to 163 kg of potassium carbonate in 250 to 1000 liters of solution.
The invention thus provides this solution and also a method of using it in aqueous ultrashort liquors, such as padding liquors, which contain fiber-reactive dyes. They may include customary dyeing auxiliaries, such as an anionic wetting agent.
The solution according to the present invention may also contain potassium hydroxide. It is preferred to replace an amount of from 10 to 40 mole % of sodium hydroxide by potassium hydroxide.
The solution according to the present invention may additionally contain further ingredients like for example sodium chloride, sodium silicate, sodium metasilicate, water glass, Glauber's salt, phosphates like tri-potassium phosphate or tri-sodium phosphate, alkali metal citrates, alkali metal polyacrylates or ethylenediaminetetra-acetic acid (EDTA) and its salts in amounts of less than 5% by weight, preferably less than 2% by weight based on the total weight of the solution. It is, however, particularly preferred if the solution according to the present invention is free of any such further ingredients.
The alkaline formulation of the invention is used according to the invention by mixing an aqueous solution of one or more fiber-reactive dyes, which optionally includes customary dyeing auxiliaries, with the alkaline formulation of the invention (generally 100 liters of an aqueous dye solution comprising about 10 to 12,000 g of dye being admixed with 2 to 17 liters of the alkaline formulation of the invention) and using the resulting alkaline dyeing liquor to impregnate a cellulosic textile material in a conventional manner, for example by spraying or padding, and fixing the dye or dyes under process conditions customary for fiber-reactive dyes.
The invention thus also provides a process for dyeing cellulosic textile material by mixing an aqueous dye solution which per liter contains for example about 0.1 to 120 g of one or mor
Negri Daniele
Schrell Andreas
Connolly Bove & Lodge & Hutz LLP
DyStar Textilfarben GmbH & Co. Deutschland KG
Elhilo Eisa
Gupta Yogendra N.
LandOfFree
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