DE2743548C3 - Process for stabilizing alkaline hydrogen peroxide bleach baths - Google Patents

Description

a) Straight or branched fatty alcohols capable of forming organic hydroperoxides Chain and more than 8 carbon atoms or their derivatives and

b) anionic and / or nonionic surfactants which have both a good wetting ability and a good emulsifying properties to the fatty alcohols under a) in durable ^I: to ^keep> emulsions and the in the alkaline Peroxidbädern at temperatures of 10O ⁰ C and above, not be decomposed.

2. The method according to claim 1, characterized in that that fatty alcohols with a carbon chain of 8 to 18 carbon atoms and the isoalcohols be used.

The alkaline activated bleaching of cotton with peroxides is controlled by a number of parameters determined: reaction time, temperature and pressure, alkali concentration and content of peroxides. Decisive for the practical failure of the continuous bleaching process at higher temperatures, however, is the Stabilization of the peroxide solutions, because bleach stands and falls with their effect. The stabilizers j> must prevent the self-disintegration of the alkaline solutions, which according to R. H. Peters (Textile Chemistry, Volume II, Elsevier Publishing Company, New York 1967, pp. 220 et seq.) By the collision of two molecules according to the following equations:

2 HjO ₂ - »2 OH + O ₂ f

This self-decomposition of the H ₂ O; If a more or less large amount of the available bleaching agent is withdrawn from the bleaching process and the desired bleaching effect, which should take place according to the equation, may not be achieved at all:

The classic stabilizers for alkaline hydrogen peroxide baths are alkali and alkaline earth silicates, the effect of which is excellent. Still it is Desire to avoid the Silikalstabilisiening, so old ω like peroxide bleach.

This is especially true for the modern alkaline bleaching processes in which the tree vines are only impregnated with alkaline peroxide solutions and then ^{heated to higher temperatures of 10O 0} C and above. This leads to shifts in concentration and pH on the fiber and silica compounds precipitate in the form of needle-shaped crystals, which not only encrust the bleached goods, but also coat the walls of the apparatus with silica deposits that cause the fabric to rub off and have to be laboriously removed from the bleaching plants from time to time. The handle of such encrusted cotton goods is hard and brittle and z. B. unsustainable for knitted and terry goods. In addition, the abrasion and puncture resistance as well as the sewability of such textiles are greatly reduced.

Various proposals have therefore been made, such as the disadvantages of waterglass stabilization can be at least partially avoided; one has the addition of borates, of ortho- and Polyphosphates, of ethylenediaminetetracarboxylic acids suggested to the bleaching baths without achieving any lasting success.

It has now been found that the alkaline peroxide solutions for continuous bleaching processes thereby can be stabilized that they are capable of forming organic hydroperoxides fatty alcohols or their derivatives with straight or branched chains and more than 8 carbon atoms ζ. B. Decano-Ie to octadecanols and their isomers, insofar as they are capable of hydroperoxide formation in the form of Emulsions are added. Also derivatives of these compounds containing ester, ether and keto groups are suitable.

The compounds forming hydroperoxides are made with the aid of anionic and / or nonionic Surfactants so emulsified. that stable emulsions are present with good wetting ability, which quickly in the Penetrate cotton goods and wet them completely, so that the cotton textiles in a short time Time to be loaded with the alkaline peroxide solutions.

It is especially important for the continue bleaching Stabilizers in the alkaline peroxide solutions are perfectly stable. The bleaching solution, with to which the raw cotton goods are impregnated must not change their wetting properties, so that the continuously running material webs are wetted evenly and loaded with the same amounts of liquid. Also the pH values of the The bleaching solutions absorbed should not fluctuate, but rather constant at the optimal value of pH 11 to 12 (see Chwala-Auger, Handbook of Textilhilfsmittel (1977), page 338). Only when these requirements are met, a uniform came about Goods with the same whiteness and uniform tear strength can be achieved. In the bleaching process, those who work in long fleets and at low temperatures will not be as sharp Requirements made because in the long bleaching liquors Bath shifts are constantly being balanced out.

The added emulsions slow down the collision of the hydrogen peroxide molecules, which leads to the Self-disintegration of bleach baths leads to especially at higher temperatures. At the same time they show next to the Braking effect against self-decomposition, also anti-catalylic Effect against metal traces, similar to that of silicate stabilizers

Thanks to their conditioning effect, the fat emulsions give the bleached cotton goods a soft and pleasant feel, as is particularly ^{required of Trikot · 1} and Frofta 'articles; knitwear bleached in this way can be easily turned into underwear on modern sewing machines,

Process pajamas and tracksuits, etc.

The process is explained in more detail by the following examples, without affecting these embodiments should be limited.

example 1

A bleach bath for treating raw mako tubular knitwear is made in the following manner manufactured:

It contains

4.0 g / l caustic soda solid
0.5 g / L MgSO ₄ · 7 H ₂ O
40.0 g / IH ₂ O ₂ (35% by weight).

As fatty compounds capable of forming hydroperoxide will

0.8 g / l hexadecanol-octadecanol mixture and
0.8 g / l wool wax or wool wax alcohol

added that with

0.7 g / l fatty alcohol sulfate from coconut alcohols and
3.0 g / l secondary alkanesulfonates

were brought into a durable emulsion.

Using this emulsion, the tricot fabric is impregnated on a padder at 3O ⁰ C and the completely durchgenetzte goods up to a pickup of 100% squeezed from the weight of the raw material. With the stockinette will now be retracted in a damper chamber, and it remains there for 30 minutes in a Sattdampfatmospf.äre at about 100 ⁰ C. The mixture is then rinsed hot and cold and _geirockne; . The DP value of the bleached goods is z. B. with PerabaumwoIIe 2390 with an initial value of the raw material of 2460; the damage factor is therefore 0.2%.

The whiteness was determined to be 88.2 compared to a whiteness of 89.0 for a whiteness below the same Conditions carried out bleach, which contains water glass as a stabilizer.

The sweat transport of the jersey is after

ίο Porous plate method according to Rees

for the raw material 50 sec.

for water glass goods 19 sec. for the goods according to the example 11 sec.

ι <> The rewettability is

for the raw material 83 sec.

0.7 seconds for the water glass goods, 0.5 seconds for the goods according to the example

20th

30 Comparative example

The claimed process was related to the hydrogen peroxide stabilization with other silicate-free Stabilizers compared and the following values were obtained: To stabilize a hydrogen peroxide bath the following; Composition:

4.0 g / l caustic soda solid
0.5 g / l MgSO ₄ - 7 H ₂ O
40.0 g / l H ₂ O ₂ (35% by weight)

were added:

Whiteness IIjO _r loss after 30 min. after "iJS hours at 90 C at 75 C 12.0% a) Stabilizer IL Example 1 88.2 4.5% of the present application 25.0% b) amino oxide stabilizer 86.6 4.5% Dimethyldodecylamine oxide 40.0% c) Protein hydrolysis stabilizer 86.2 15.0% 43.0% d) Mg salt of a dodecyl sulfate 85.2 7.0%

The tricot obtained according to the claimed method is characterized by a particularly soft and comfortable grip and excellent sewability

Claims (1)

2 H2O2> 2 HjO + O; HjO2 + H2O + HO2 10 claims: 1. Process for stabilizing alkaline hydrogen peroxide bleach baths at higher temperatures, characterized in that emulsions are added to the bleach baths which