DE4206929A1 - Vat-dyeing cellulose@ textiles with water insoluble dye - comprises redn. to leuco-dye in aq. alkali medium using complexes of ferrous cpd. and aliphatic hydroxy cpd. with carbonyl gp., and oxidn. - Google Patents

Abstract

Dyeing or printing comprises reducing dye to the leuco-form prior to oxidn. to pigment redn. is effected in an aq. alkali medium using a redn. agent based on complexes of divalent Fe with aliphatic hydroxy cpd. complexers which also contain in addn. to the OH gp. further OH gps. and/or up to 2 aldehyde, keto or carboxyl gps. but not amino gps. Pref. hydroxy cpd. complexer is a di- or poly-alcohol or a mono-, di- or poly-hydroxy-aldehyde, -ketone or -mono or -dicarboxylic acid, typical disclosed examples including (di)ethylene glycol, glycerin aldehyde, glucose, hydroxyacetone, ascorbic acid and tartaric acid. Prepn. of the Fe(II) complex can be in-situ, esp. for 1 molar Fe(II) salt and 3-15 mols. hydroxy cpd. complexer. ADVANTAGE - Difficulties associated with the use of triethanolamine or citric acid as complexers (i.e. Fe(III) hydroxide deposition and poor results with difficultly reducible dyes such as C.I. Vat Black 25 (C.I. 69 525)) are overcome.

Description

The present invention relates to an improved method ren for dyeing cellulosic textile material with Kü pen dyes by applying the water-insoluble color from aqueous liquor onto the textile material, reduction to the leuco form and subsequent oxidation to the pigment.

The dyeing of cellulosic textile material with vats Dyes is well known. To the water-insoluble Vat dye to give the required substantivity hen, d. H. He has to fix it on the textile material first by reduction in its highly hydrophilic waterless Liche converted and then by oxidation again to develop the dye pigment.

Usually, when dyeing piece goods after the konti worked in a two-bath process, where in one first aqueous bath of the dye and in a second aqueous rig-alkaline bath, the reducing agent is applied. In this way, the dye can not be applied before application react to the fiber with the reducing agent, and a uneven dyeing of the textile material (uncontrolled End flow) is prevented. Depending on whether it is after the Applying the dye an intermediate drying takes place or not, one speaks of the so-called pad-steam method or Wet-steam method.

However, especially for dyeing yarns is also after the discontinuous one-bath process worked in which the Dye in the presence of the reducing agent on the fiber is applied.

Common reducing agent in vat dyeing is sodium dithionite. In its application, however, it comes in particular with more sensitive vat dyes as a result of Überreduk tion to unwanted color changes. In addition, will the wastewater is contaminated by sulfite ions.  

As an alternative reducing agent are iron (II) complex with Triethanolamine or citric acid. This connection Although not lead to overreduction, but the Color depths of the dyeings obtained with them, especially at heavier reducing dyes such as C.I. Vat Black 25th (C.I. 69 525). In addition, in the Verwen tion of citric acid as complexing agent frequently Ver yellowing of the product by precipitation of iron (III) hydroxide to observe, so that a subsequent cleaning is required.

The invention therefore an object of these deficiencies remedy and suitable reducing agents for the Küpenfär to prepare.

Accordingly, a method of dyeing cellulose has been proposed gem textile with vat dyes by applying the water-insoluble dye from aqueous liquor on the Textile material, reduction to leuco form and subsequent Oxidation to the pigment found, which characterized characterized net is that the reduction in aqueous alkaline medium with reducing agents based on complexes of the two valent iron with aliphatic hydroxy compounds as Complexing agents, which in addition to the hydroxyl group still one or more hydroxyl groups and / or up to two aldehydes, Keto or carboxyl groups, but no amino group enthal theses.

Preferred complexing agents are di- or polyalcohols, mono-, Di- or polyhydroxyaldehydes, ketones, mono- and dicarboxylates acids.

The number of carbon atoms of the complex according to the invention bildner is not critical in itself, as long as the used Complexing agents or their iron (II) complexes soluble in water are. However, for reasons of wastewater treatment Hy hydroxy compounds having 2 to 7 carbon atoms, in particular More preferably 2 to 4 carbon atoms.

As examples of preferred hydroxy compounds ge mentioned are:

• Di- or polyalcohols such as ethylene glycol, diethylene glycol col, pentaerythritol, 2,5-dihydroxy-1,4-dioxane, sugar alcohols such as glycerol, erythritol, hexitols such as mannitol, dulcitol and especially sorbitol;
• Mono-, di- or polyhydroxy aldehydes such as glycolaldehyde, Glyceraldehyde, triosereductone, sugar (aldoses) like Mannose, galactose and especially glucose;
• - Mono-, di- or polyhydroxyketones such as especially hydro xyacetone and dihydroxyacetone, besides 1-hydroxybuta non- (2) and sugars (ketoses) such as fructose;
• - Mono-, di- or Polyhydroxymonocarbonsäuren such as hydro xyacetic acid, α- and β-hydroxypropionic acid, glycerol acid and especially sugar acids such as gluconic acid, gluco heptoic acid and ascorbic acid, also mono-, di- or poly hydroxydicarboxylic acids such as tartronic acid, malic acid, Tartaric acid, sugar acid and mannosaccharic acid as well
• - Their mixtures, for example glycerose (Glycerinal dehyd + dihydroxyacetone) or lactose hydrolyzate (Ga lactose + glucose).

The complexing agents are very particularly preferred, the themselves already have a reducing effect, for example hydroxy acetone, dihydroxyacetone and glucose.

The iron (II) complexes can be prepared by mixing aqueous solutions of iron (II) salts, in particular of iron (II) sulfate, too Iron (II) sulphate chloride, ferrous chloride, with one or more several possibly also dissolved in water complex image ners or their salts, in particular alkali (sodium) salts the hydroxycarboxylic acids, initially prepared separately and then the reduction liquor in the form of the preparation mixture be added. To lower the salt load of the fleets It is also possible to use freshly precipitated iron (II) hydroxide be solved by adding the complexing agent again becomes. It is advantageous that the complexes as aqueous, above all lem as neutral or acidic, with a strong complexion ner as dihydroxyacetone but also as an alkaline, solution or paste storable.  

The complexes can also be in situ, d. H. only in the Re production fleet, produced by mixing the components become. In this case, the alkali of the liquor is preferred added only after the complex formation.

Iron (II) compound and complexing agent are in one Molar ratio of usually 1: 3 to 1:15, preferably 1: 4 to 1: 9, used. In general, therefore, is also about schüssiger complexing agent in the alkaline reduction fleet, thereby increasing the stability of the iron (II) complex and the egg formed in the reduction of the vat dye sen (III) complex is increased.

Is the redox potential of a reducing agent mixture at very low values (eg below -1000 mV) and is the Danger of over-reduction of vat dye, then that can Potential by addition of iron (III) salts, such as iron (III) Sulfate, chloride or other salts, targeted to less ne negative values. Iron (III) is sufficient amounts of usually 0.1 to 20, preferably 1 to 10 mol%, based on the amount of iron (II), to a potential to reach about +100 to +150 mV. By This redox buffering can also be used with sensitive vat color such as C.I. Vat Blue 4, 6, 12 and 14 (C.I. 69 800, 69 825, 69 840 and 69 810) safely avoided over-reduction become.

As usual in the vat dyeing, the Reduk tion fleet also preference in the process according to the invention example by the addition of sodium hydroxide solution as an inorganic base alkaline.

The required alkali concentration depends on it according to the dye used. She should go up be less than 80% in the leucoanion leucosis to convict. Become acidic ferrous salts (eg sulphate) and / or hydroxycarboxylic acids used as complexing agents, Thus, in addition to their neutralization stoichiometry required amounts of alkali.

Even at concentrations of about 45 to 50 g NaOH / l liquor are the iron (II) complexes of the invention stable and we the formation of iron (II) - still of iron (III) hydroxide  Precipitation is observed. It also shows in egg In the range of about 10 to 50 g NaOH / l surprisingly an increase of the redox potential, so that it is difficult to reduce ornamental dyes easily converted into the leuco form can be. At higher alkali concentrations this remains Reducing power about the same or decreases slightly.

The preferred working area is therefore for the textile Loading in continuous dyeing usually at 2 to 100 g of complexing agent and 6 to 60 g of NaOH per kg of textile material and for dyebaths in exhaust dyeing usually at 1 to 90 g of complexing agent and 6 to 65 g of NaOH per liter of reduct tion fleet.

The reducing agents according to the invention can be advantageous for the known continuous and discontinuous Dyeing process and also used for textile printing become.

For continuous colorations by the pad-steam method is the Reducing agent fleet for a fleet order of 60 to 100% preferably composed as follows:

complexing 3-70, especially 3-35 g / l FeSO₄ · 7 H₂O 0.5-15, especially 0.5-8 g / l Sodium hydroxide solution (38 ° B ') (440 g NaOH / l) 20-140, especially 20-110 ml / l

In this case, the molar ratio of iron to complexing agent preferably 1: 4 to 1: 9. Also when using the low complex concentrations can themselves dyes like C.I. Vat Black 25 can be easily reduced.

Of course, the fleets can in this case like also in all other cases usual dyeing aids such as Wetting agents and antimigration agents included.

For the coloring of warp yarns with indigo you can do that Reducing the Nachsatz and also the or the Därbebä to admit. Preferably, the addition is carried out in the post-sentence:

Indigo | 40 g / l complexing 25-40 g / l FeSO₄ · 7 H₂O 3-15 g / l Sodium hydroxide solution (38 ° B') 60-120 ml / l

The higher concentrations apply to the systems the larger number of air flows.

For the production of a cooling pressure after the two-phase Printing process can reduce the pressure with the vat dyes subjected to drying with a reducing agent liquor as indicated above for the continuum staining.

For discontinuous bath dyeings, mostly in fleets Ratio 1: 5 to 1:20 are recommended following bath compositions:

dye upon need complexing 5-80 g / l FeSO₄ · 7 H₂O 1.5-20 g / l Sodium hydroxide solution (38 ° B') 10-120 ml / l

The order of addition of the individual components can are largely freely chosen, provided complexing agents and Iron (II) salt before adding caustic soda to the liquor or be well premixed to the stock batch. So it can be the Dye precursor (Pigmentierverfahren) and then the Kom plexifying agent and the ferrous salt separated or mixed be given or vice versa. But you can also dye, Pre-chill complexing agent and iron (II) salt and then the lye to be dosed, whereby particularly level dyeings he can be kept.

The reductive fixation of the dye on the Textilmate Depending on the type of dye and of the reducing agent in all cases by cold hold or by steaming, preferably 30 to 150 seconds in saturated Steam area, done. Especially when printing is the Steaming because of the lower risk of Abklatschens vorzu be pulling.  

The further completion of the dyeing by rinsing, oxidation Ren, soaps and neutral rinses also corresponds to the usual working method. Remain traces of iron hydroxide the goods, which can be seen by a yellow cast, so they can by acidification, for example, with oxalic acid place of acetic acid or by the addition of oxalic be already when soapy or at the beginning of rinsing easy be be sideways. As a rule, this aftertreatment will ever but not necessary, since the iron complexes with the Complexing agents according to the invention are sufficiently stable.

With the aid of the method according to the invention, cellulose can be used containing textile material advantageously with vats dyes dyed or printed. The reducing Effect of the iron (II) complex according to the invention is large ge nug to easily incorporate even sparingly reducible dyes on the other hand, she calls no overreduction with more sensitive dyes. Furthermore, the complexing agents according to the invention are in the Location, both the Fe (II) ions used as well as the complexing the reaction formed iron (III) ions and to prevent the formation of iron hydroxide precipitation countries. In addition, the complexing agents are usually good buildable and thus pose no problem for the Abwasseraufbe preparation.

Examples A) Continuous staining Examples 1 to 6

A cotton fabric having a basis weight of 250 g / m ² was treated with an aqueous dyeing liquor
35 g / l of the vat dye K
2 g / l wetting agent and
10 g / l anti-migration agent
contained, impregnated abge squeezed to 70% liquor pickup and dried with air at 120 ° C.

Subsequently, the pigmented tissue for Verkuppung at 20 ° C with a reducing agent fleet, the
xg / l (or ml / l) complexing agent X
6 g / l FeSO ₄ .7H ₂ O and
100 ml / l sodium hydroxide solution (38 ° Be)
contained, impregnated, squeezed again to 70% liquor pickup and steamed immediately in an air-free damper at 100 ° C for 2 min.

The completion was done in the usual way by spü len, oxidizing and soaps.

The slight yellowing of the goods (examples 2, 4 and 5) could by substitution of acetic acid by oxalic acid last rinse are eliminated.

The redox potential was in the freshly prepared Re production liquors at room temperature of about -900 to -1050 mV (measured with Pt / calomel electrode under far going air exclusion).

Further details of these experiments and their results Table 1 can be found.  

B) bath dyeing Examples 7 to 13

A cotton knit fabric was dyed in a liquor ratio of 1:20 (Examples 8 to 13, liquor ratio 1:10) after the exhaust process at 60 ° C for 45 min with a dye liquor, the
2 g / l CI Vat Black 25
xg / l (or ml / l) complexing agent X
yg / l FeSO ₄ .7H ₂ O and
100 ml / l sodium hydroxide solution (38 ° Be)
contained.

The completion of the dyeing was done in the usual way Wise.

The measurement of the redox potentials revealed in the fresh Dye baths set values from -810 to -1050 mV and in the cooled baths after staining values of -690 to -810 mV (measured at room temperature with Pt / calomel Electrode).

Details of these experiments and their results are listed in Table 2.  

C) pressure C1) two-phase pressure Example 14

A ready-pre-treated cotton fabric (linen weave, basis weight 132 g / m ² ) was coated with 3 different printing pastes containing

• a) 8 g of CI Vat Red 10 (CI 67 000)
  800 g stock thickener (8 wt .-% thickener, 92 wt .-% water) and
  192 g of water.
• b) 25 g of CI Vat Black 25
  800 g trunk thickening and
  175 g of water.
• c) 50 g of CI Vat Black 25
  800 g trunk thickening and
  150 g of water

printed in 3 strips (about 140 g / m ² ) and then dried in a garret.

Subsequently, a reducing agent fleet, the
24 g / l dihydroxyacetone
7 g / l FeSO ₄ .7H ₂ O and
90 ml / l sodium hydroxide solution (38 ° Be)
applied to the printed fabric (73% liquor pick-up).

For development, one half of the product was 15 min leave at room temperature (cold), the the other half was steamed at 100 ° C for 90 sec.

The further completion took place at a part the product in a shortened procedure by oxidation over an aisle and then soaps and  Rinse and in the other part in usual Way with the help of a Badoxidation.

Regardless of the type of follow-up was in all cases a pressure obtained by very good color yield and good contour sharpness distinguished. A yellowing of the white fund was not observed.

C2) direct pressure Example 15

The same cotton fabric as in Example 14 was in direct printing with 3 different printing pastes in Printed stripes.

The printing pastes were prepared as follows:

First, an aqueous solution of 200 g / l FeSO ₄ · 7H ₂ O under extensive exclusion of air with ver dilute sodium hydroxide solution (44 g NaOH / l) was adjusted to pH 11.5. The case precipitated Ei sen (II) hydroxide was filtered off, washed twice with What water and used as a wet filter cake for Her position of the stock preparation.

The master batch had the following composition:
5 g / kg Fe (OH) ₂ , wet
26 g / kg dihydroxyacetone
95 ml / kg sodium hydroxide (38 ° Be)
95 g / kg thickener
794 g / kg of water.

From the masterbatch were 3 ready to use Printing pastes, containing

• a) 800 g stock
  8 g of CI Vat Red 10
  192 g of water.
• b) 800 g stock
  25 g of CI Vat Black 25
  175 g of water.
• c) 800 g stock
  50 g of CI Vat Black 25
  150 g of water

manufactured.

The printed with these printing pastes goods was like usually dried in a printing mansard.

The development was carried out analogously to Example 14 men, whereby in some of the goods the Dampfkondi tion on the damper has been switched off and with an extremely dry, overheated steam gearbei was tet.

The further completion took place in usual Wise.

In all cases, a flawless printer result received.

Claims (5)

1. A process for dyeing or printing cellulosic textile fabric with vat dyes by applying the water-insoluble dye from aqueous liquor to the textile material, reduction to leuco form and subsequent oxidation to the pigment, characterized in that the reduction in aqueous alkaline medium with reducing agents on the basis of complexes of bivalent iron with aliphatic Hydroxyverbindun conditions as complexing agents, in addition to the hydroxyl group or one or more hydroxyl groups and / or up to two aldehyde, keto or carboxyl groups, but no amino group, performs. 2. The method according to claim 1, characterized in that as hydroxy compounds di- or polyalcohols, Mono-, di- or polyhydroxy aldehydes, ketones, mono- or dicarboxylic acids. 3. The method according to claim 1 or 2, characterized net, that the hydroxy compounds 2 to 7 carbon contain atoms. 4. Process according to claims 1 to 3, characterized marked characterized in that the iron (II) complexes in situ Iron (II) salts and the hydroxy compounds produced. 5. The method according to claim 4, characterized in that while the iron (II) salts and the hydroxy compounds in a molar ratio of 1: 3 to 1:15.