FR2572416A1 - IMPROVEMENT TO THE OXIDATION PROCESS OF SULFUR COLORANTS - Google Patents

Abstract

PROCESS FOR OXIDIZING SULFUR COLORANTS OR TANK COLORANTS. THE OXIDATION BATH CONTAINS HYDROGEN PEROXIDE, A METAL SALT PREFERABLY A COPPER SALT AND AN ALKALINE VANADATE.

Description

The present invention relates to an improvement

  oxidation and fixation of dyes

sulfur, or vat dyes.

  It is known that the oxidation, after dyeing, of

  sulfur dyes or vat dyes can be achieved

  using different oxidation agents. It is possible, for example, to mention among the most widely used compounds: chromates or dichromates of alkali metals; halogenated compounds of alkali metals such as bromates, chlorites or iodates;

- Hydrogen peroxide.

  However, the use of chromates or dichromates has the disadvantage of causing significant pollution of the wastewater. It is also known that these compounds can significantly alter the tone of certain

  colors or also cause a decrease in the hydro-

phility of the fibers.

  The use of halogenated derivatives is frequently recommended, especially in the presence of alkaline vanadate; we

  knows, however, that these different compounds are difficult to

  can be used with certain devices, such as

the Jigger.

  The use of hydrogen peroxide is effective in alkaline medium but has the disadvantage

  to cause the overoxidation of many dyes.

  As for the use of hydrogen peroxide in acidic medium, it does not allow to oxidize all the dyes. It is known that certain metals are capable of activating the decomposition of an aqueous dilution of hydrogen peroxide and increasing the rate of its oxidizing power in a pH-acid range. The use of iron salts, nickel or copper, for example, such as copper sulphate, can strongly activate the decomposition of hydrogen peroxide. However, such an oxidation, carried out for example in the presence of copper salts, causes a significant modification of the

various colors.

  On the other hand, the use of a vanadate in a bath of hydrogen peroxide does not allow to increase

  the rate of oxidation of the oxy-

dante.

  On the other hand, the plaintiff found

  that the presence in a bath of hydrogen peroxide

  gene, small amounts of a metal salt, such as copper sulfate, insufficient quantities to increase the rate of oxidation and allow the development of various colors, and simultaneously the presence in the bath

  small amounts of a vanadate, allows rapid oxidation

  all colors without the disadvantage of

change their tone.

  Comparatively, the separate application of

  identical parts of copper sulphate or vanadate

  does not oxidize so quickly all of the various

  dyes. On the other hand, the simultaneous application of a

  date and a metal salt in the presence of hydrogen peroxide

  drogen allows to quickly oxidize all dyes

  sulfur, irrespective of the dyeing process or the

reillage considered.

  The subject of the present invention is therefore a

  oxidation of sulfur dyes or dyes

  tank which makes it possible to avoid the various disadvantages mentioned

  born and is characterized by the implementation of hydrogen peroxide solutions, added with small amounts of an alkali vanadate and a metal salt, simultaneously present. The oxidation is carried out in a relatively acidic medium, in a pH range of between 3 and 6, at

  temperatures between 20 and 95 C and preferably

between 40 and 6000 C.

  As metal salts, the various compounds of copper, iron, nickel, cobalt or manganese may be employed. However, according to the invention, preference is given to the use of copper salts, such as

than copper sulphate.

  Vanadate may be selected from the family comprising alkali metal vanadates and vanadate

of ammonium.

  The required quantities of hydrogen peroxide

  according to the invention, between 0.1 g and

  g / l, preferably between 1 g and 5 g of hydrogen peroxide

  per liter of oxidation bath.

  The amount of vanadate will be between 0.05 and 0.5 g of vanadate per liter, preferably between

0.1 and 0.2 g / l.

  The amounts of the metal salt chosen may vary between 0.01 g and 1 g / l with preferably 0.05 to

  0.1 g, for example copper sulphate per liter of bath.

  Thanks to the invention, all the sulfur dyes or vat dyes, can be oxidized regardless of the dyeing process, the equipment retained or

the nature of the dyed fibers.

  The following examples will illustrate, in a non-limiting manner, the possibilities offered by the present invention. In the following examples, the corresponding sulfur red is used in the Color Index at number 55228. This dye corresponds to one elements that are difficult to oxidize and give the most

  difficulties during oxidation.

EXAMPLE I

  You dyed a cotton cloth, previously

  bleached with 10% of red with sulfur (90%)

  compared to the weight of the fiber). We adopt the

  following portions for the dyebath: 10% /% sodium sulphide dye

% sodium chloride.

  A bath ratio of 1 to 10 is adopted between the weight of the fiber and the volume of the dye bath. We realize

  dyeing for 1 hour at the temperature of 950C.

  After dyeing, rinse with warm water then cold, divide the sample into three parts and proceed to

  the oxidation of the dye on each of these separate parts

by operating as follows:

  A - One of the parties is treated in a solution

  containing 2 g / l of 30% hydrogen peroxide and

cm3 of acetic acid.

  The oxidation is carried out for 15 seconds at

the temperature of 50 C.

  B - For the second part, one operates under the same conditions by introducing more in the bath

  oxidant 0.2 g / l sodium vanadate.

  C - For the third part, one adopts identical conditions but by introducing in the bath, in accordance with the invention, 2 g / l of sodium chlorite

  at 30% and 0.2 g / l sodium vanadate.

  The following results are observed: Samples A and B: very slow oxidation, clearly insufficient, not making it possible to oxidize the color,

  Sample C: Total and rapid oxidation.

EXAMPLE 2

  The dyeing is carried out as in Example 1. After dyeing and rinsing, the sample is divided into

  four parts A, B, C, D, and proceed to the oxidation -

  of the colorant of these parts by means of the following respective baths: Bath for Part A - 2 g / 1 H2o2 3ao% cc / 1 acetic acid Bath for Part B - 2 g / l -H202 at 30%

cc / 1 acetic acid -

  0.05 g / 1 copper sulphate Bath for part a -2 g / l H2O2 at 30% cc / 1 acetic acid 0.1 g / l sodium vanadate Bath for part D-2g / l H202 at 30% cc / 1 Acetic acid 0.05 g / 1 copper sulphate 0.1 g / l sodium vanadate For all these baths, the following conditions are adopted: Temperature 50 C - Bath ratio I to 20 (ratio between

  the weight of the fiber and the volume of the bath).

  An insufficient rate of oxidation is observed with the baths A, B and C, the total oxidation of the color is, for example, not carried out after 30 seconds of treatment. In comparison, the oxidation carried out at D is significantly faster; in this case, a total oxidation is observed after 10 seconds of treatment;

  we also note that the color has not undergone any change

tone.

EXAMPLE:

  We take the previous conditions. The oxidation is carried out on three separate parts of the dyed and rinsed fibers, using respectively the following baths: A) 2 g / l H 2 O 2 at 30% 10 cc / l acetic acid B) 2 g / l H 2 O 2 & 30% cc / acetic acid 0.05 g / l copper sulphate C) 2 g / l H 202 30% 10 cc / l acetic acid 0.2 g / l copper sulphate After treatment, the oxidation carried out with the baths A

  and C is clearly insufficient. Comparatively, the oxidation

  C is much faster. However, in the latter case, the color undergoes a

  significant blueness and is no longer in accordance with

  cations of the dye considered. Note that in this example there is no vanadate in the composition of the bath.

EXAMPLE 4

  We make a dye on Jigger with 10%

dye.

  After dyeing, the oxidation is carried out by operating under the following comparative conditions:

  A. Rinse by Jigger using two pass-

in cold water.

  B. Oxidation on Jigger with: 3 g / l H202 at 30 / cc / 1 acetic acid 0.1 g / 1 copper sulfate

0.1 g / l sodium vanadate.

  Two passages are made at the temperature of

   C. There is rapid and complete oxidation of the

seems of the dyed matter.

  C. The same conditions are used but the oxidation is carried out with a bath free of hydrogen peroxide and containing: 3 g / l of sodium chlorite at 30% 0.2 g / l of sodium vanadate

cc / 1 acetic acid.

  In this case, there is a very markedly incomplete oxidation of the dyed material whatever

  the number of passages made in the oxidizing bath.

  The preceding examples show the effectiveness of

  cited the combined action of hydrogen peroxide, a

  metal salt and an alkaline vanadate, present simultaneously

element in the oxidation bath.

Claims (12)

  Process for the oxidation of sulfur dyes or vat dyes in the presence of a solution of hydrogen peroxide, characterized in that this solution is activated using a metal salt and a vanadate alkali acting in combination.   2. Method according to claim 1, characterized   in that the metal salt may be selected from the various salts of iron, copper, nickel, cobalt and manganese with a preference for use copper salts.   3. Process according to claim 1 or 2, characterized in that the vanadate is chosen from the family comprising alkaline vanadates and vanadate. ammonium.   4. Method according to one of claims 1 to   3, characterized in that the amount of metal salts   is between 0.01 and 1 g per liter of oxidizing bath.   5. Process according to claim 4, characterized   in that the amount of metal salt is included between 0.05 and 0.1 g / l.   6. Method according to one of claims 1   at 5, characterized in that the amounts of vanadate are between 0p, 5 and 0.5 g / l.   7. Process according to claim 6, characterized   rised in that the quantities of vanadate are included between 0.1 and 0.2 g / l.   8. Method according to one of claims 1   to 7, characterized in that the amount of hydrogen peroxide   is between 0.1 and 30 g / l.   9. The method of claim 8, characterized   rised in that the amount of hydrogen peroxide is between 1 and 5 g / l.   10. Method according to one of the claims   1 to 9, characterized in that the oxidation is carried out in   acid medium, in a pH range between 3 and 6.   11. Method according to one of claims 1   at 10, characterized in that the oxidation is carried out at   a temperature between 20 and 95 C.   12. The method of claim 11, wherein   in that the oxidation is carried out at a temperature of between 40 and 6000 C.