DYSTAR TEXTILFARBEN GMBH & CO. DEUTSCHLAND KG 2007/D506 / DrMy

Dyeing polyester-cotton blend fabrics

The present invention relates to a process for dyeing polyester-cotton blend fabrics with disperse and reactive dyes.

Many apparel articles and other textile products consist of blend fabrics composed of polyester and cotton, which are widely used because of their advantageous properties. To dye these blend fabrics, the polyester portion is generally dyed with a disperse dye, while there is a choice of several classes of dyes for the cotton portion. More particularly, vat dyes, sulfur dyes as well as reactive dyes can be used, as required.

A number of dyeing processes are available for dyeing with disperse and reactive dyes, and they are extensively described in the literature. Owing to the very different dye- and fiber-specific requirements of the dyeing conditions, the disperse and the reactive dye are frequently applied separately in two steps with or without a reduction clear being carried out between the steps for fastness improvement. This procedure is extraordinarily cost-intensive and requires large amounts of chemicals (electrolytes), water and energy.

Owing to these disadvantages, an ecologically and economically optimized one-bath processing procedure has been sought in the past. For instance, a one-bath thermosol-thermofix (TT) process with disperse and reactive dyes is described in Textilindustrie 167, Nos. 5, 6, 7. DE 28 09 675 discloses a process for one-bath dyeing of polyester/cellulose fiber under neutral conditions, while a one-stage processing procedure is described in Melliand Textilberichte 3/1980, 261-265 wherein the disperse and reactive dyes, a solubilizer and a mild alkali donor are padded onto the fabric, which is subsequently dried, thermosoled and washed.

These processes are all based on the idea of utilizing the thermosoling step also to carry out the reaction of the reactive dyes with the cellulose. Disadvantages here are the possible interactions with the auxiliaries used, such as urea and dispersants, or else with the disperse dyes used. In addition, use of dicyandiamide is obligatory with this processing procedure. There have also been reported disadvantages in manufacture such as, in particular,

poor reproducibility and poor fastnesses.

There accordingly continues to be a need for an improved process which is economical and does not have the above-described disadvantages. It has now been found that, surprisingly, these prerequisites are met when the drying step is carried out with a defined steam-air mixture and accordingly the reactive dye is fixed at this stage rather than later.

The present invention accordingly provides a process for dyeing a polyester-cotton blend fabric with disperse and reactive dyes in a one-bath process in which a padding liquor comprising dyes, alkali and a buffering system is padded onto the fabric and subsequently dried and thermosoled, which comprises (i) using sodium bicarbonate and/or sodium carbonate as alkali and borax or boric acid as buffer, and (ii) drying at 100 to 150 ⁰ C and 20% to 40% by volume relative humidity and subsequently thermosoling at 190 to 230 ⁰ C without intervening step.

Any reactive dye can be used in principle. Reactive dyes are known to one skilled in the art and are extensively described in the literature, for example in the Colour Index published by the British Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists.

Preferred reactive dyes have a monoazo, polyazo, metal complex azo, anthra- quinone, phthalocyanine, formazan or dioxazine chromophore. When there are two or more chromophores in a reactive dye, these can also belong to different ones of the abovementioned groups.

Reactive dyes have a reactive group capable of forming covalent bonds with the hydroxyl groups of cellulosic materials or with the carboxamide groups of natural or synthetic polyamide materials. Such reactive groups are preferably so-called vinyl sulfone hooks or heterocyclic hooks. Vinyl sulfone hooks conform in particular to the formula -SO2-Z, where Z represents vinyl or -CH ₂ CH ₂ Z ¹ and Z ¹ represents hydroxyl or an alkali-detachable group. Alkali-detachable groups include in particular halogen atoms, such as chlorine and bromine, ester groups of organic carboxylic and sulfonic acids, such as alkylcarboxylic acids, optionally substituted benzenecarboxylic acids and optionally

substituted benzenesulfonic acids, such as the groups alkanoyloxy of 2 to 5 carbon atoms, in particular acetyloxy, benzoyloxy, sulfobenzoyloxy, phenylsulfonyloxy and toluylsulfonyloxy, acidic ester groups of inorganic acids, as of phosphoric acid, sulfuric acid and thiosulfuric acid (phosphato, sulfato and thiosulfato groups), also dialkylamino groups having alkyl groups of 1 to 4 carbon atoms each, such as dimethylamino and diethylamino.

Preferably, however, Z represents vinyl, β-chloroethyl and more preferably β-sulfatoethyl.

Heterocyclic hooks conform for example to the formulae (1), (2) or (3)

(1) (2) (3) where

V represents fluorine or chlorine;

U ¹ and U ² independently represent fluorine, chlorine or hydrogen; Q ¹ and Q ² independently represent chlorine, fluorine, cyanamido, hydroxyl,

(CrC ₆ )-alkoxy, phenoxy, sulfophenoxy, mercapto, (CrC^-alkylmercapto, pyridino, carboxypyridino, carbamoylpyridino or a group of the formula (4) or (5)

.R ¹

— N — N

W-SO ₂ Z R ³

(4) (5) where

R ¹ represents hydrogen or (CrC ₆ )-alkyl, sulfo-(Ci-C ₆ )-alkyl or phenyl which is unsubstituted or substituted by (CrC ₄ )-alkyl, (CrC ₄ )-alkoxy, sulfo, halogen, carboxyl, acetamido, ureido;

R ² and R ³ independently have one of the meanings of R ⁸ or form a cyclic ring system of the formula -(CH ₂ )j- where j represents 4 or 5, or of the formula -(CH ₂ )2-E-(CH ₂ )2-, where E represents oxygen, sulfur, sulfonyl or -NR ¹¹ and R ¹¹ represents

(Ci-C ₆ )-alkyl;

W represents phenylene, which is unsubstituted or substituted by 1 or 2 substituents, such as (Ci-C ₄ )-alkyl, (Ci-C ₄ )-alkoxy, carboxyl, sulfo, chlorine, bromine, or

(Ci-C ₄ )-alkylene-arylene or (C ₂ -C ₆ )-alkylene, which may be interrupted by oxygen, sulfur, sulfonyl, amino, carbonyl, carboxamido, or represents phenylene-CONH- phenylene, which is unsubstituted or substituted by (CrC ₄ )-alkyl, (C _r C ₄ )-alkoxy, hydroxyl, sulfo, carboxyl, amido, ureido or halogen, or represents naphthylene, which is unsubstituted or substituted by one or two sulfo groups; and Z has one of the abovementioned meanings.

In the above definitions, (C ₁ -C ₄ )- and (CrC ₆ )-alkyl groups may be straight chain or branched and represent in particular methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl and tert-butyl. Preference is given to methyl and ethyl. The same logic holds for alkoxy and alkylene groups.

Halogen represents in particular fluorine, chlorine and bromine, of which fluorine and chlorine are preferred.

Examples of particularly preferred reactive dyes are the hereinbelow disclosed reactive dyes of the formulae (FR1) to (FR6). The dyes are each indicated in the form of their sodium salts, but can also be present in the form of other alkali or alkaline earth metal salts or in the form of the free acid.

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Reactive dyes are commercially available, for example under their Colour Index designation or under trade names such as in particular Remazol ^® , Levafix ^® and Procion ^® (Remazol, Levafix and Procion are registered trademarks of DyStar Textilfarben GmbH & Co. Deutschland KG).

Any disperse dye is suitable in principle. Disperse dyes are known to one skilled in the art and are extensively described in the literature, for example in the Colour Index published by the British Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists.

Preferred disperse dyes are those which have sufficient stability, especially sufficient pH stability, under the conditions of the process according to the present invention. Disperse dyes which are stable at pH values between 7 and 11 are particularly preferred. Such dyes are in particular monoazo, anthraquinone, quinophthalone and methine dyes. Particularly preferred disperse dyes are azo dyes of the formula (6)

where

A represents the residue of a diazo component

R ⁴ represents hydrogen, (d-C ₄ )-alkyl, (Ci-C ₄ )-alkoxy, -NHCO(C _r C ₄ )-alkyl,

-NHSO ₂ (CrC ₄ )-alkyl or halogen; R ⁵ represents hydrogen, (CrC ₄ )-alkyl or (CrC ₄ )-alkoxy; and

R ⁶ and R ⁷ independently represent hydrogen, (C ₂ -C ₄ )-alkenyl, (CrC ₄ )-alkyl,

(Ci-C ₄ )-alkyl substituted by cyano, hydroxyl, phenoxy, (CrC ₄ )-alkoxy,

-OCO(C _r C ₄ )-alkyl, -OCOphenyl, -OCOO(C _r C ₄ )-alkyl or -OCOOphenyl.

Examples of group A conform in particular to the formula (7)

where

T ¹ and T ² independently represent hydrogen, halogen, (Ci-C ₄ )-alkyl, (Ci-C ₄ )-alkoxy,

cyano, -Sθ ₂ (CrC ₄ -alkyl) or nitro; and

T ⁴ and T ³ independently represent hydrogen, halogen, trifluoromethyl, cyano,

-SO ₂ CH ₃ , -SCN or nitro; or to the formula (8)

where

T ⁵ and T ⁵ independently represent hydrogen or halogen; and

T ⁶ represents hydrogen, -SO ₂ CH ₃ , -SCN, (CrC ₄ )-alkoxy, halogen or nitro; or to the formula (9)

where

T ¹² represents hydrogen or halogen.

Further particularly preferred disperse dyes are anthraquinone dyes of the formula (10)

where

D ¹ and D ² independently represent hydrogen, hydroxyl, amino or nitro;

D ³ and D ⁴ independently represent hydroxyl, amino or -NHR ⁸ ;

D ⁵ and D ⁶ independently represent hydrogen, halogen, cyano, (C _r C ₆ )-alkoxy, hydroxy-(Ci-C ₆ )-alkoxy, phenoxy-(Ci-C ₆ )-alkoxy, phenoxy, phenoxy substituted by

(CrC ₄ )-alkyl, cyano-(Ci-C ₆ )-alkyl, hydroxyl, halogen, (CrC ₄ )-alkoxy or

(Ci-C ₄ )-alkyl-COO-(Ci-C ₄ )-alkyl, phenyl, phenyl substituted by hydroxyl, (C _r C ₄ )-alkyl or (C _r C ₄ )-alkoxy, -SO ₂ Ophenyl, -CO(C _r C ₄ )-alkyl or -COO(C _r C ₄ )-alkyl; and

R ⁸ represents (CrC ₄ )-alkyl, hydroxy-(Ci-C ₄ )-alkyl, phenyl, phenyl substituted by (C _r C ₄ )-alkyl, (C _r C ₄ )-alkoxy, hydroxy-(C _r C ₄ )-alkyl, -OSO ₂ (CrC ₄ )-alkyl or halogen, -SO ₂ -phenyl or -SO ₂ -phenyl substituted by (C _r C ₄ )-alkyl in the phenyl radical.

Further particularly preferred disperse dyes are quinophthalone dyes of the formula (11)

where R ⁹ represents hydrogen or halogen, in particular bromine; R ¹⁰ represents hydrogen or -COOR ¹¹ , and R ¹¹ represents hydrogen, (C _r C ₄ )-alkyl or (C ₁ -C ₄ )-alkoxy-(C ₁ -C ₄ )-alkoxy.

A further particularly preferred disperse dye is the methine dye of the formula (12)

2)

In the above definitions, (C ₁ -C ₄ )- and (C _r C ₆ )-alkyl groups may be straight chain or branched and represent in particular methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl and tert-butyl. Preference is given to methyl and ethyl. The same logic holds for alkoxy and alkylene groups.

Halogen represents in particular fluorine, chlorine and bromine, of which fluorine and chlorine are preferred.

Examples of particularly preferred disperse dyes as well as the methine dye of the formula (12) are the hereinbelow disclosed disperse dyes of the formulae (FD1) to (FD14)

(FD1)

Disperse dyes are commercially available, for example under their Colour Index designation or under trade names such as in particular Dianix ^® (Dianix is a registered trademark of DyStar Textilfarben GmbH & Co. Deutschland KG)

Alkali is used in amounts of preferably 5 to 30 g/l and more preferably of 10 to 20 g/l. Sodium bicarbonate is preferably used as alkali.

The buffer is used in amounts of preferably 5 to 30 g/l and more preferably in amounts of 10 to 20 g/l, and borax is preferred.

The process of the present invention is particularly preferably carried out without the addition of dicyandiamide.

Drying is preferably carried out with a steam-air mixture which has the requisite temperature and in which the requisite humidity is established. The steam-air mixture can be regulated by regulating the exit air stream or by steam injection into the drying air or by a combination thereof.

Drying is preferably done at temperatures of 110 and 130 ⁰ C, while the relative humidity is preferably in the range from 25% to 30% by volume. It is particularly preferable to dry with a steam-air mixture at temperatures of 110 and 130 ⁰ C and a relative humidity of 25% to 30% by volume.

Drying time is generally between 60 and 300 seconds more preferably between 120 and 240 seconds. Drying time can be regulated via the circulating air speed, the moisture content and the temperature of the drying air.

The drying step is followed by the thermosoling step. In the thermosoling step, the fabric is preferably heated to a temperature of 200 to 220 ⁰ C. Preferably, after it has reached the desired temperature, the fabric dwells at this temperature for 30 to 120 seconds, preferably 45 to 90 seconds.

The padding liquor may be applied on any continuous assembly developed for this purpose. Such assemblies are known to one skilled in the art. Drying has to be done on an assembly equipped with the technical facilities for establishing and regulating the necessary temperature and the necessary humidity. Such assemblies are known

and are available for example from Monforts and Bruckner. The thermosoling operation can be carried out on any suitable assembly, although it is customary to use hot flues or tenters.

The dyeings obtained by the process of the present invention can subsequently be washed and soaped in a known manner. This step takes place at temperatures of 70 to 95°C in particular and can be carried out on a commercially available, continuous washing assembly having a plurality of compartments.

In contrast to the known processes of the prior art, in which reactive dyes are fixed during the thermosoling step as well as disperse dye, the process of the present invention has the reactive dye being fixed during the drying step. This provides advantages, especially in relation to the build-up of the dyes in deep shades, which were hitherto not possible in one-bath processes. This is because one-bath processes typically require distinctly higher pH settings at which, however, disperse dyes are normally unstable.

Example 1

A textile web of polyester-cotton blend fabric (50% PES, 50% cotton) was impregnated in a continuous assembly with a padding liquor of the following composition:

2 g/l of a commercially available anionic wetting agent (ammonium bis(2-ethylhexyl) phosphate),

10 g/l of a commercially available migration inhibitor (based on sodium polyacrylate)

5 g/l of a commercially available penetration accelerant (based on polymeric amides),

10 g/l of sodium bicarbonate,

10 g/l of borax, 5.5 g/l of the commercially available disperse dye Dianix ^® Yellow S-G plv

5.5 g/l of the commercially available disperse dye Dianix ^® Cherry CC plv,

0.64 g/l of the commercially available disperse dye Dianix ^® Blue S-2G plv,

8.5 g/l of the commercially available reactive dye Levafix ^® Amber CA gran,

9 g/l of the commercially available reactive dye Remazol ^® Ultracarmine RGB plv,

and

0.22 g/l of the commercially available reactive dye Levafix ^® Blue CA gran (Dianix, Levafix and Remazol are registered trademarks of DyStar Textilfarben GmbH & Co. Deutschland KG)

This was followed by predrying with infrared radiation to reduce the wet pickup by 20-50%. Further drying took place at a temperature of 125°C with a steam-air mixture in which a humidity (volume) of 270% is established. The steam-air mixture was regulated via appropriate regulation of the exit air stream. Drying time was 180 seconds.

The fabric was subsequently heated to a temperature of 210 ⁰ C in a hot flue. The fabric dwelled at 210 ⁰ C for 70 seconds.

The result was a rust-brown dyeing which was subjected to the customary after-wash.

Example 2

Example 1 was repeated with a padding liquor of the following composition:

2 g/l of a commercially available anionic wetting agent (ammonium bis(2-ethylhexyl) phosphate),

10 g/l of a commercially available migration inhibitor (based on sodium polyacrylate)

5 g/l of a commercially available penetration accelerant (based on polymeric amides), 10 g/l of sodium bicarbonate,

10 g/l of borax,

5 g/l of sodium carbonate,

1.20 g/l of the commercially available disperse dye Dianix ^® Rubine CC plv,

18.00 g/l of the commercially available disperse dye Dianix ^® Black CC-R plv, 3.00 g/l of the commercially available reactive dye Levafix ^® Red CA gran and

30.00 g/l of the commercially available reactive dye Remazol ^® Deep Black GWF gran.

The result was a dark gray dyeing which was subjected to the customary after-wash.