Bleaching and dyeing; fluid treatment and chemical modification – Dye or potential dye composition – additive – treatment,... – Mixed dyes – noncomplexed
Patent
1997-12-18
1999-07-13
Einsmann, Margaret
Bleaching and dyeing; fluid treatment and chemical modification
Dye or potential dye composition, additive, treatment,...
Mixed dyes, noncomplexed
8662, 8922, 8933, D06P 354, D06P 382
Patent
active
059220899
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for dyeing textile polyester and polyester-containing textile materials with red dicyanoazo dyes.
In general, textile polyester or polyester-containing textile materials are dyed with disperse dyes from an aqueous dyeing bath at HT conditions in a temperature range of from 120 to 140.degree. C. and at pH values of from 4 to 6. This is due to the fact that disperse dyes are partly or completely destroyed at higher pH values. Accordingly, dyeing at higher pH values results in losses in color strength and shifts in hue, as a result of which the dyeings are not reproducible. Usually, the polyester fiber is subjected in a separate step, prior to dyeing, to an alkaline rinsing treatment in order to remove auxiliaries used during weaving or spinning of the fiber. Examples of these auxiliaries are oiling and sizing agents which when present would make it difficult or impossible to achieve level dyeing of the polyester fiber. The alkaline treatment is also carried out in order to destroy oligomers of the polyester fiber which during the dyeing process have migrated from the interior of the fiber and give the dyeing an unlevel appearance and in order to retain them in the aqueous dyeing liquor. The oligomers mentioned are undesirable especially in yarn dyeing because during spinning of the dyed yarns in the spinning apparatus they become deposited in the form of powders as a result of abrasion in those places where the yarn is deflected. They thus soil the apparatus and cause the yarn to tear.
This alkaline rinsing treatment is advantageously carried out at elevated temperature. To save time and energy and to reduce the number of apparatuses required for the two processes, alkaline pre-treatment and dyeing, the goal has always been to combine the two processes to one single-bath rinsing and dyeing process. However, in order to achieve this goal, it is necessary to develop processes producing reproducible dyeings in an aqueous dyeing bath at pH 8 to pH 11.
Polyester/cellulose or polyester/polyamide blend fabrics are usually dyed with disperse or reactive dyes in two dyeing steps from an aqueous dyeing bath. As mentioned above, the disperse dyes are applied to the polyester portion at pH 4 to pH 6 and the reactive dyes to the cellulose or polyamide portion in the pH range between 11 and 13. Here, too, the goal in the past has been to develop a single-bath application process for both classes of dyes. For this single-bath application process, it was necessary to find reactive dyes which can be dyed at pH values of as low as 8 to 11, and this method also required processes which ensure that the polyester portion can be reproducibly dyed with disperse dyes under these conditions.
To overcome the deficiencies of the previous processes, DE-A 3,938,631 describes a method in which dyeing with disperse dyes takes place in the pH range between 8 and 10 in the presence of at least one amino acid which, if desired, may substituted on the nitrogen atom and/or an alkali metal salt of an amino acid which, if desired, may be substituted on the nitrogen atom.
Thus, for example, this method allows brilliant red dyeings in the shade of the anthraquinonoid dye C.I. Disperse Red 60 at pH 9.5 (Use Example 33 of DE-A 3,938,631 or its equivalent U.S. Pat. No. 5,019,133) to be obtained using the dye of the formula ##STR2##
However, the alkali resistance of this dye is not sufficient for dyeings at higher pH values or for carrying out the abovementioned rinsing treatment in an efficient manner. The same is also true of the commercially available mixture of the dyes of the formula ##STR3## which, at higher pH values, exhibits losses in color strength and shifts in hue. This is probably due to the acidity of the sulfonamide hydrogen, such as described, for example, in R.O.C. Norman "Principles of Organic Synthesis", Methnen and Co. Ltd. and Science Paperbacks, 1968, on page 66. According to this reference, when dyeing at higher pH values, the acidity mentioned results in at least partial dye salt forma
REFERENCES:
patent: 4452609 (1984-06-01), Hamprecht
patent: 4968318 (1990-11-01), Wregner et al.
patent: 5013133 (1991-05-01), Himeno et al.
patent: 5279621 (1994-01-01), Buhler
DyStar Japan Ltd.
Einsmann Margaret
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