WO2000014324A1

WO2000014324A1 - Method of dyeing cotton/wool blends

Info

Publication number: WO2000014324A1
Application number: PCT/AU1999/000717
Authority: WO
Inventors: David William Smith
Original assignee: Rocklea Spinning Mills Pty Ltd.
Priority date: 1998-09-07
Filing date: 1999-09-01
Publication date: 2000-03-16
Also published as: AUPP570898A0

Abstract

A process for one-bath exhaust dyeing of a fibre material including a blend of cotton and shrink resistant wool, the process including contacting the fibre material with a dye bath ocmposition including: a first reactive dye which is reactive with cotton at low salt concentrations and optionally a second reactive dye which is reactive with wood; and an anionic blocking agent for reducing the uptake of dye by the wool.

Description

METHOD OF DYEING COTTON/WOOL BLENDS

CottonΛΛ/ool blends have found a significant niche within the Textile Industry, being able to offer benefits that neither natural fibre in it's sole state can, for example: absorbency with warmth, comfort without prickle and the ability to be worn across a wide temperature range, just to name a few.

One of the major reasons that cotton/wool has not played a more significant role within the Industry is the lack of knowledge for wet processing, in particular the dyeing, of the fibre blend. It can be generally stated that cotton and wool are at opposing ends of the dyeing scale: methods for dyeing wool are generally unfavourable towards cotton and those favourable towards cotton may damage or even completely destroy the wool.

The trade off for dyeing intimate blends of cotton and wool has historically been to use complicated and lengthy methods, generally two-bath, without being able to attain dark shades with high degrees of wet fastness, in particular fastness to washing. Also the difficulty in attaining solid shades on both fibres was a major concern as wool is far more readily dyed than the cotton.

Appreciating the general difficulties in dyeing cotton and wool blends, it must be stressed that these difficulties are compounded many times when replacing the (untreated) wool with it's machine washable counterpart.

Generally speaking, machine washable wool is wool that has undergone chemical modification (usually chlorination followed by a resin application) in order to make it's surface smoother, reducing the ability for adjacent fibres to lock together during washing. Unfortunately for the dyer, this chemical modification permits a far more rapid uptake of dyestuff onto the wool and thus colouration of machine washable wool in a blend requires far closer attention than untreated wool.

We have developed a process for one-bath exhaust dyeing of a fibre material including a blend of cotton and shrink resistant wool, the process including contacting the fibre material with a dye bath composition including: a first reactive dye which is reactive with cotton at low salt concentrations and optionally a second reactive dye which is reactive with wool; and an anionic blocking agent for reducing the uptake of dye by the wool.

The invention further provides a dye bath composition for dyeing fibre material which includes a blend of cotton and shrink resistant wool the composition including: a first reactive dye which is reactive with cotton at low salt concentrations and optionally a second reactive dye which is reactive with wool; and an anionic blocking agent for reducing the uptake of dye by the wool.

The dye bath composition will typically include a low salt concentration of for example less than 50 grams salt per litre of composition. The process of the present invention will preferably include a predye treatment. Conventional pretreatments typically involve alkaline scouring. We have found that the evenness in partition of dyes between the wool and cotton is significantly improved if the alkaline pretreatment normally used is replaced by the use of near-neutral to slightly acidic pH. Accordingly it is particularly preferred that the process of present invention include a pre-dyeing step of scouring the fibre material using an aqueous detergent at a pH of from 5 to 7.5 and more preferably 5.5 to 7.0. Typically the scouring will use a detergent, sequestrant and antifoam agent.

The dye bath composition used in the invention includes a dye which is reactive with cotton at low salt concentrations. Such dyes are known in the art as low salt dyes and have a high standard affinity for cotton in the presence of low amount of electrolyte such as common salt or Glauber's salt.

The preferred low salt dyes comprise two fluorotriazine groups linked by an aliphatic diamine bridging group particularly alkylenediamine bridges. Examples of low salt dyes include compounds of Formula I.

in which A₁ and A₂, independently of one another, are the radical of a monoazo, polyazo, metal complex azo, anthraquinone, phthalocyanine, formazan, azomethine, dioxazine, phenazine, stilbene, triphenylmethane, xanthene, thioxanthone, nitroaryl, naphthoquinone, pyrenequinone or perylenetracarbimide dye;

R_{1 τ} R₂, R₃ and R₄, independently of one another, are hydrogen or C C₄ alkyl, which can be substituted by halogen, hydroxyl, cyano, C_rC₄ alkoxy, C_rC₄ alkoxycarbonyl, carboxyl, sulfamoyl, sulfo or sulfato; B is an aliphatic bridging member; and X., and X₂, independently of one another, are fluorine, chlorine, bromine, sulfo or carboxypyridinium.

Examples of this type of low salt dye are provided in Australian Patent 677575 in the name of Ciba-Geigy AG the contents of which are herein incorporated by reference. Examples of suitable dyes are available commercially from Ciba-Geigy under the trade mark "CIBACRON LS".

The second reactive dye used in the process of the invention may be selected from a range of wool reactive dyes known in the art. Preferred wool reactive dyes are selected from sulphonated azo and anthraquinone dyes having one or two bromoacrylamide reactive groups.

The most preferred wool reactive dyes are those available from Ciba

Geigy AG under the trade mark "LANASOL". The concentration of dyes in the bath will of course depend upon the shade and colour of the required product and appropriate concentrations can be determined without undue experimentation.

The blocking agent used in the dye bath composition of the invention is a hydrophobic anionic agent adapted to strongly compete with the low salt dye for the available active dye-binding sites of wool. Typically the amount of the blocking agent is in the range of from 1 to 7% by weight of the fibre product to be dyed. Most preferably the amount of blocking agent is from 1 to 5% based on the weight of fibre product. Typical examples of anionic blocking agents include formaldehyde condensation products of aromatic sulphonic acids such as the product

"CIBATEX RN" (Ciba Geigy) DYAPOL WX-A (Yorkshire), DYAPOL SB-40A

(Yorkshire), BAL MESITOL BWS (Bayer Australia Ltd.), THIOTAN WPN (Clariant), ERIONAL RF (Ciba) and ERIONAL NW (Ciba).

Preferably the blocking agent is contacted with the fibre material prior to the fibre material contacting the dyestuffs.

The process of the invention has the significant advantage that it may be carried out in one dye bath which provides a significant advantage over two bath procedures used in the prior art.

The process of the invention may be carried out by initially setting the bath at neutral pH and a temperature from ambient temperature to about 40° with a salt such as common salt or Gauber's salt, optionally auxiliaries and blocking agent. The dyestuffs including the first and second dyes are added and the temperature of the dyebath increased typically to about 70-90°C and maintained at this temperature for a period, typically 1 minute to 1 hour. Fixation of the first dye is typically enhanced by increasing the pH of the bath to within the range of about 9 to 12 by addition of a base such as soda ash and holding for a further time, typically 1 minute to 1 hour. We have found that the dye bath composition and process of the invention significantly improve the evenness of dyeing of mixtures of wool and cotton. It is particularly useful in dyeing to provide darker colours such as colours of standard depth 1/1 or darker.

The invention is demonstrated by, but in no way limited to, the following Examples.

Example 1

This example demonstrates the use of the invention in dye machine washable cotton/wool yarn blends on a pilot bulk dying scale. The yarn contained 70% cotton and 30% chlorine Hercosett Wool.

Pre-treatment Scouring was performed using detergents to adequately remove cotton waxes under neutral to slightly acid pH ranges. The scour formulation was:

0.25gpl Albatex FFC Antifoam/De-aerator Ciba

0.50gpl Verolan NBO Base Sequesterant Rudolf 2.50gpl Croscolor SDCF Detergent CTC

Scouring was commenced at 40°C and the mixture heated to 90°C for 30 mins. and a pH was about 6.5. The bath was drained at 80°C and rinsed.

Dyebath: The technique can be classified as a one bath, two-stage reactive/reactive dyeing.

The dyebath was set to 30°C and pH 7.0 with salt and auxiliaries as follows:

0.25gpl Albatex FFC Antifoam/De-aerator Ciba LOOgpl Matexil PAL Anti-reducing agent BASF

0.50gpl Verolan NBO Base Sequesterant Rudolf

30.0gpl Dairy Salt (NaCI)

5.0% Cibatex RN Blocking Agent Ciba Dyestuffs shown below were added after 15 minutes and the temperature raised to 90° at a rate of 1.5°C/min and held for a further 30 mins. Cooling to

70°C was carried out at a rate of 1.0°C per minute and fixation of the cotton reactive dye was performed using only 5gpl soda ash (attaining a pH range of 9.8 - 10.2). Dyestuffs:

0.22% Lanasol Yellow 4G Wool Reactive Ciba

0.27% Lanasol Blue 3G Wool Reactive Ciba

0.50% Cibacron Blue LS-3R Low Salt Cotton Reactive Ciba

0.70% Cibacron Orange LS-BR Low Salt Cotton Reactive Ciba 1.10% Cibacron Navy LS-G Low Salt Cotton Reactive Ciba

1.28% Cibacron Yellow LS-R Low Salt Cotton Reactive Ciba Post-Treatments:

The yarn was then cold rinsed and neutralised with 1.0gpl acetic acid (60%). The yarn was drained after 15 minutes and soaping was conducted twice at 90°C using CIBAPON R detergent (Ciba). Each time the mixture was heated to 90°C (pH 7.5) for 15 minutes before draining and rinsing. Cationic fixing was then carried on in a known manner.

Example 2

This example demonstrates the dying of yarn of a 70% cotton 30% chlorine Hercosett wool blend to a bright red colour.

Pretreatment

Scouring was performed in accordance with the corresponding proceder of Example 1. Dyebath

The dyebath procedure used was as described in the corresponding step of Example 1 with the exception that the dyestuffs used were as follows:

0.82% CIBACRON Red LS-B Low salt cotton reactive (Ciba)

4.00% CIBACRON Scarlet LS-2G Low salt cotton reactive (Ciba) Post treatments were performed using the procedure of Example 1.

Examples 3-9

In the following Examples 3-9 the procedure of Example 1 was repeated with the exception that the dairy salt concentration, blocking agent concentration and identity and concentration of dyestuffs was changed as set out below.

Example 3

This example demonstrates the use of the process of the invention to produce a navy colour. 5.00% Cibatex RN

50gpl Dairy Salt (NaCI) 0.150% Lanasol Yellow 4G

0.700% Lanasol Navy MBN

0.900% Cibacron Red LS-B

0.990% Cibacron Orange LS-BR

2.530% Cibacron Navy LS-G

Example 4

The Example demonstrates use of the invention to produce a cherry (red) colour.

5.00% Cibatex RN

30gpl Dairy Salt

0.073% Cibacron Blue LS-3R

0.290% Cibacron Scarlet LS-2G

2.230% Cibacron Red LS-B

Example 5

This Example demonstrates use of the invention to produce a mist (light mauve) colour.

3.00% Cibatex RN

10gpl Dairy Salt

0.030% Lanasol Red 6G

0.044% Lanasol Blue 3R

0.008% Cibacron Orange LS-BR

0.034% Cibacron Blue LS-3R

0.038% Cibacron Red LS-B

Example 6 This Example demonstrates use of the invention to produce a bottle green colour.

5.00% Cibatex RN 50gpl Dairy Salt

0.120% Lanasol Yellow 4G

0.160% Lanasol Blue 3G

0.450% Cibacron Orange LS-BR

1.460% Cibacron Yellow LS-R

2.840% Cibacron Blue LS-3R

Example 7 This Example demonstrates use of the invention to produce a black colour.

5.00% Cibatex RN

50gpl Dairy Salt

0.500% Lanasol Blue 3G

9.000% Cibacron Black LS-N

Example 8

This Example demonstrates use of the invention to produce a junior navy colour.

5.00% Cibatex RN

50gpl Dairy Salt

0.240% Lanasol Blue 3G

0.230% Cibacron Orange LS-BR

0.490% Cibacron Red LS-B

2.860% Cibacron Blue LS-3R

Example 9

This Example demonstrates use of the invention to produce a tomato red colour. 5.00% Cibatex RN

50gpl Dairy Salt

0.010% Lanasol Red 6G

0.012% Cibacron Blue LS-3R

0.980% Cibacron Orange LS-BR

2.300% Cibacron Red LS-B

Advantaqes of the method: Quick one-bath method applicable to both yarn and fabric dyeing.

Very high wet fastness, especially wash fastness. The technique provides wet fastness superior to other techniques currently available. Ability to attain solid shades across a wide colour spectrum. Ability to attain deeper shades than other methods without causing excessive damage to the wool.

Very good reproducibility. Exceptional levelness of (yarn) dyeing.

Neutral pre-treatment was found to provide a significant improvement in the evenness of dye partitioning. If "standard" alkaline preparation is employed, even in conjunction with this dyeing technique, results are significantly worse.

Assuming the pre-treatment is followed correctly, substitution of the Cibacron LS dyes with "conventional" high salt/low affinity reactive dyes, will result in either:

1. Longer processing times, possibly requiring two-bath methods, leading to wool damage.

2. The inability to attain deep shades.

3. Poor dyeing partitions.

4. Poor reproducibility.

5. Higher alkaline requirements to attain build-up of shade on the cotton, leading to damage of the wool.

6. Lower wet fastness of the product. Inclusion of Cibatex RN in the dyebath is a necessity. If the blocking agent is omitted, dyeing partition swings heavily towards the wool and an unsatisfactory result occurs.

Finally, it is to be understood that various alterations, modifications and/or alterations may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or ambit of the invention. made without departing from the spirit of the present invention as outlined herein.

Claims

CLAIMS:

1. A process for one-bath exhaust dyeing of a fibre material including a blend of cotton and shrink resistant wool, the process including contacting the fibre material with a dye bath composition including: a first reactive dye which is reactive with cotton at low salt concentrations and optionally a second reactive dye which is reactive with wool; and an anionic blocking agent for reducing the uptake of dye by the wool.

2. A process according to claim 1 wherein the dyebath composition has a salt concentration of less than 50g salt.

3. A process according to claim 1 further including a pre dyeing treatment of scouring the fibre material using an aqueous detergent at a pH of from 5 to 7.5.

4. A process according to claim 3 wherein the pH is in the range of from 5.5 to 7.0 and the scouring is conducted in the presence of a sequestrant and antifoam agent.

5. A process according to claim 1 wherein the first active dye comprises one or more dyes having two fluorotriazine groups linked by an aliphatic diamine bridging group.

6. A process according to claim 1 wherein the first dye comprises one or more compound of formula I:

in which A and A₂, independently of one another, are the radical of a monoazo, polyazo, metal complex azo, anthraquinone, phthalocyanine, formazan, azomethine, dioxazine, phenazine, stilbene, t phenylmethane, xanthene, thioxanthone, nitroaryl, naphthoquinone, pyrenequinone or perylenetracarbimide dye;

R^ R₂, R₃ and R₄, independently of one another, are hydrogen or C_rC₄ alkyl, which can be substituted by halogen, hydroxyl, cyano, C C₄ alkoxy, C_rC₄ alkoxycarbonyl, carboxyl, sulfamoyl, sulfo or sulfato; B is an aliphatic bridging member; and X-, and X₂, independently of one another, are fluorine, chlorine, bromine, sulfo or carboxypyridinium.

7. A process according to claim 1 wherein the dye bath composition includes a wool reactive dye.

8. A process according to claim 7 wherein the wool reactive dye includes one or more dyes selected from sulphonated azo and anthraquinone dyes having one or two bromoacrylamide reactive groups.

9. A process according to claim 1 wherein the anionic blocking agent includes formaldehyde condensation products of aromatic sulphonic acids.

10. A process according to claim 9 wherein the blocking agent is present in an amount of from 1 to 7% by weight to the fibre material to be dyed.

11. A process according to claim 1 wherein the blocking agent is contacted with the fibre material prior to the fibre material contacting the dyes.

12. A dye bath composition including: a first reactive dye which is reactive with cotton at low salt concentrations and optionally a second reactive dye which is reactive with wool; and an anionic blocking agent for reducing the uptake of dye by the wool.