Continuous dyeing of yarns

Details Continuous dyeing of yarns Continuous dyeing of yarns

1994-07-13

1996-05-21

Einsmann, Margaret

Bleaching and dyeing; fluid treatment and chemical modification

Replenishment or replacement of same bath liquor in dyeing...

8650, 8651, 8652, 8653, D06P 500, D06P 122

Patent

active

055185088

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION

It is known, in the continuous dyeing of warp yarns, to add the dye in the form of a concentrated stock vat. Customarily 4-8 dip compartments equipped with squeezeoff means are used for applying the vatted dye. Squeezing takes place between the dipping steps and the dye is oxidized by air passage.
To avoid dye depletion of the dip vats, which are usually operated with squeezeoff effects of 60-90% wet pickup, the dye is replenished from stock vats having a concentration greater than 30 g/l. In the case of dyes where the leuco form is not very soluble, such as C. I. Vat Blue 5, the stock vat concentrations used are in some instances above the solubility product of the leuco form; that is, dispersions of the leuco form are used. In industrial practice such liquors tend to give rise to problems, especially as regards color constancy.
It is an object of the present invention to avoid the problem of supersaturated or else insufficiently concentrated stock vats.
We have surprisingly found that this object is achieved when, in the continuous dyeing of yarns with vat dyes, a dye dispersion is used instead of a stock vat.
Suitable for the process of the invention are for example aqueous dispersions of vat dyes containing dyes having a vatting half-life of .ltoreq.20, preferably .ltoreq.5, minutes. To increase the rate of vatting, the dyes can be used for example in very finely divided form. Usually the dyes or preparations supplied by the renowned vat dye manufacturers are already suitable. In the case of dyes not already optimized, they can be converted into a suitable form by known methods, for example ultrasonic dispersion.
The vatting rate is essentially determined by the chemical structure, the crystallinity and crystal structure and by the particle size. For a given chemical structure, high vatting rates are obtained for example with amorphous, finely divided dyes.
A high vatting rate is desirable because it keeps the concentration of unvatted dye in the dip liquor at a low level.
Another way of limiting the concentration of unvatted dye in the dip bath is by adding the dyes via a bypass mixing tank.
According to the invention, vat dyes can be used not only individually but also in combination. In the case of combinations it is possible, in particular with dyes of different substantivities, to control the dye availability through separate metering means.
Suitable substrates for dyeing are all-cellulose yarns or cellulose-containing blend yarns which are subsequently predominantly made into denim articles.
The number of dip passages generally varies within the range from 1 to 8. Depending on the dye and the reducing agent, dyeing temperatures from 20.degree. to 95.degree. C. can be used.
The process of the invention produces pronounced ring dyeings as a prerequisite for the worn denim look.
Advantageously, dye dispersions and solutions containing alkali and reducing agent are added separately.
Suitable reducing agents are the compounds known for vat dyeing, for example sodium dithionite, thiourea dioxide or organic reducing agents such as hydroxyacet-one. It is also possible to use mixtures of reducing agents.
Dyes suitable for the process of the invention are in particular the compounds listed in the Colour Index as vat dyes and also vattable disperse dyes, with or without prior appropriate dispersion. Preference is given to for example C.I. Vat Blue 5 (C.I. 73065), C.I. Vat Orange 2 (C.I. 59705), C.I. Vat Blue 4 (C.I. 9800), C.I. Vat Red 32 (C.I. 71135), C.I. Vat Green 1 (C.I. 59825), C.I. Vat Green 9 (C.I. 59850) or Disperse Yellow 54 (C.I. 47020).
Details of the process according to the invention are given in the following Examples, in which parts and percentages are by weight, unless otherwise stated:


EXAMPLE 1

In 4 troughs of an indigo open-width dyeing machine for dyeing cotton warps, which has a total capacity of 3,500 1 (including pipework and circulation tank), a dyeing vat is prepared in the following composition:


______________________________________ 0.45 g/l of C.I. Vat Blue 5 (C

REFERENCES:
patent: 1399230 (1921-12-01), Touchstone et al.
patent: 1652649 (1927-12-01), Tice
patent: 4629465 (1986-12-01), Hasler et al.
patent: 5176715 (1993-01-01), Horn
M. Peter et al "Grundlagen der Textilveredlung", 1 Feb. 1991, Deutscher Fachverlag pp. 146-148, 500-502.

Affiliated with

Also associated with

Rating

Continuous dyeing of yarns does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Continuous dyeing of yarns, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Continuous dyeing of yarns will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2034707