Dye composition

Details Dye composition Dye composition

2000-09-22

2002-04-02

Powers, Fiona T. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Azo

C008S639000

Reexamination Certificate

active

06365718

ABSTRACT:

The present invention relates to novel dye compositions for dyeing cellulose acetate fibres, especially secondary acetate fibres and blends of secondary acetate fibres with other fibres both natural and synthetic.
Mixtures of disperse dyes are well known for the dyeing of synthetic fibres, particularly for polyester and for secondary celulose acetate fibres and their blends with other fibres.
Polyester fibres in particular are well served both in the inventive art of, and in the commercial availability of, disperse dye mixtures which provide navy and black shades with good application properties and good fastness to washing and to light. Many such mixtures based upon the mixture of two or more dyes of general structure (I), where X may be hydrogen or alkoxy, and R and R′ may be alkl or alkenyl. Such mixtures are exemplified in, for example U.S. Pat. No. 5,393,308 (to BASF) and GB 1,582,743 (to ICI), and commercially provide economic navy and black shades of adequate fastness when applied to polyester.
These mixtures, and many other mixtures which are based upon high energy dyes, are however unsuitable for the dyeing of secondary cellulose acetate.
It is an object of the present invention to provide novel disperse dye mixtures, based upon known dyes, which are especially suitable for the dyeing of secondary cellulose acetate.
Secondary cellulose acetate fibres are commonly used as linings on coats and suits. Dyeing of the fibres usually takes place at less than 100° C. at atmospheric pressure in water. The main commercial acetate fibre dyes are black. However, very few companies offer good black dyes for acetate fibres.
Dyes of formula (II) and (III), as identified hereafter, are previously known dyes for the dyeing of synthetic fibres. The preparation of dye (II), and the use of the dye in the coloration of aromatic polyester textile materials is exemplified in example 1 of UK patent 1,394,367 (ICI). Commercial preparations of the dye are available and recommended for use on polyester fibres as Dispersol Blue XF (trade mark BASF) and Serilene Blue HWF (trade mark Yorkshire Chemicals). However, dye (II) has never to the applicant's knowledge been used on acetate fibres before.
Dye (III) is disclosed in claim 5 and page 10 of UK Patent 1,112,146 (BASF) and is commercially available and recommended for use on polyester fibres as Palanil Dark Blue 3RT (trade mark BASF) and Serilene Dark Blue RT-LS (trade mark Yorkshire Chemicals). Two new (&bgr;- and &ggr;-) crystal forms of dye (III) are disclosed in UK patent 1,438,586 (BASF).
No previous use of the dyes (II) and (III) in admixture for the coloration of textiles has been found, and there is no suggestion in the prior art that (II) and (III) should be combined.
According to a first aspect of the present invention there is provided a dye composition for dyeing fibres comprising
(a) an azo dye of the formula (II):
or a salt thereof, and
(b) an azo dye of the formula (II):
or a salt thereof.
When referring to dyes (II) and (III) throughout the specification, the salts thereof are intended to be included. The same applies for dyes (IV) to (IX) define hereinafter.
The dye composition of the present invention is blue, and can form the basis of navy and black dye compositions for providing navy or black shades on, for example, secondary cellulose acetate fibres.
The dye composition is especially suitable for dyeing secondary cellulose acetate fibres. From the resultant dyeings, it has been found that the dye compositions of the present invention display fastness properties superior to those provided by dye compositions currently available for the provision of navy and black shades on secondary cellulose acetate. This superior fastness extends to blends of secondary cellulose acetate with other fibres, for instance with wool, viscose fibres and synthetic elastomeric fibres.
The exact shade achieved by the blue mixture or composition of the present invention may be changed by varying the proportions of the two dyes, and may be varied further by the addition of one or more further blue dyes to the dye composition.
Preferably, the dye composition comprises from 20% to 80% of dye (II) and from 20% to 80% of dye (III), by weight of the total amount of dyes (II) and (III) in the composition.
The BASF inventors of UK patent 1,438,586 claim that the &bgr;- and &ggr;-forms or modifications of the dye (III) disclosed therein have better stability under liquor dyeing conditions (100-200° C., eg. up to 140° C.) and better rheological properties than the &agr;-form (crystal form) or &agr;-modification of dye (III), which was previously known for dyeing of polyester and cellulose acetate. However, the present inventor has now found that, contrary to the indications in GB 1,438,586, the &agr;-form is actually superior for dyeing cellulose acetate (eg. secondary acetate) fibres giving a better rate of dyeing than the &bgr;- and &ggr;-forms of dye (III), so that a shorter time is required in the dye bath, and producing a more on-tone build up of the required navy or black shade on the fibres. Without being bound by theory, this quicker dyeing is thought to be because the &agr;- form of dye (III) has a greater solubility than the &bgr;- and &ggr;-forms in the dye bath at typical acetate dyeing temperatures of about 75-85° C. This increased solubility in turn is probably because the &agr;-form of (III) is less thermodynamically stable and has a lower melting point and crystal energy than the &bgr;- and &ggr;-forms.
The &agr;-form of dye (III) has an X-ray diffraction graph (CuK
&agr;
radiation) having a characteristic line of strong intensity at a diffraction angle 2&thgr; of 25.50°, and lines of medium intensity at diffraction angles of 5.9°, 12.1°, 13°, 14.2°, 15.9°, 17.8°, 18.4°, 24.1°, 26° and 28°.
Therefore, in a particularly preferred embodiment of the present invention, some or all of the dye (III) is present in an &agr;- form characterised substantially by the above X-ray diffraction graph. Preferably ≧50%, more preferably ≧80%, even more preferably≧95% and most preferably 100% of the dye (III) is present in the &agr;-form.
Alternatively, the dye (III) can comprise or can be present in, or some or all of the dye (III) can be present in, the &bgr;-form and/or the &ggr;=form of dye (III). The &bgr;- and &ggr;-crystal forms of dye (III) are disclosed in UK patent 1,438,586, and are characterised substantially by x-ray diffraction graphs (CuK
&agr;
radiation) as follows:
&bgr;-form: line of strong intensity at a diffraction angle 2&thgr; [°] of 25.3; lines of medium intensity at diffraction angles 2&thgr; [°] of 7.3, 13.6, 13.9, 16.7, 21.1, 23.1 and 29.0; and optionally lines of weak intensity at diffraction angles 2&thgr; [°] of 14.3, 18.3, 19.8, 22.6 and 26.1. &ggr;-form: line of strong intensity at a diffraction angle 2&thgr; [°] of 24.5; lines of medium intensity at diffraction angles 2&thgr; [°] of 10.9, 18.3 and 22.3; and optionally lines of weak intensity at diffraction angles 2&thgr; [°] of 9.0, 17.8, 20.8, 23.2, 26.2, 27.6 and 28.0.
Optionally, the dye composition additionally comprises an azo dye of the formula (VI) and/or an azo dye of the formula (IX):
or one or more salts thereof.
The dyes (VI) and (IX) are also blue and further vary the shade achieved by a basic blue composition containing dyes (II), (III) and [(VI) and/or (IX)] and no other dyes.
Preferably, the dye composition comprises from 20% to 70%, or more preferably from 30% to 60%, of dye (VI) or of dye (IX) or of the total weight of dyes (VI) and (IX), by weight of the total weight of dye (II) and dye (III) in the composition.
Other blue dyes may also be used in addition to or instead of dyes (VI) and (IX), and may be present in the same proportions as those preferred for (VI) and/or (IX).
Preferably, the dye composition comprises one or more additional dyes (preferably azo dyes) adapted to give the dye composition and/or fibres with which the composition comes into contact a b

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