Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06L—DRY-CLEANING, WASHING OR BLEACHING FIBRES, FILAMENTS, THREADS, YARNS, FABRICS, FEATHERS OR MADE-UP FIBROUS GOODS; BLEACHING LEATHER OR FURS
  • D06L4/00—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs
  • D06L4/10—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which develop oxygen
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06L—DRY-CLEANING, WASHING OR BLEACHING FIBRES, FILAMENTS, THREADS, YARNS, FABRICS, FEATHERS OR MADE-UP FIBROUS GOODS; BLEACHING LEATHER OR FURS
  • D06L4/00—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs
  • D06L4/30—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using reducing agents

Definitions

• the invention relates to a process for the reductive and oxidative bleaching of wool in aqueous liquors, in which the oxidative and reductive bleaching are carried out in succession in the same bath.
• wool can be bleached with hydrogen peroxide in the alkaline range at a pH of 8 to 10, in the neutral and in the weakly acidic range.
• Hydrogen peroxide bleaching is often carried out in the form of long-term alkaline bleaching because of possible damage at relatively low temperatures of 20 to 50 ° C. in 4 to 12 hours and, for example, in the presence of sodium pyrophosphate as a buffer. At these temperatures, the bleaching process is very slow and the simultaneous use of brighteners is not possible in this pH and temperature range.
• the object of the invention is to demonstrate a bleaching process which, with a high bleaching effect, corresponds to short-term bleaching in a simple and time-saving manner and which, if necessary, enables the simultaneous use of optical brighteners.
• the solution to the problem consists in a process for single-bath reductive and oxidative bleaching of wool in aqueous liquors, which is characterized in that in an aqueous bath containing buffer substances, complexing agents, hydrogen peroxide activators and optionally optical brighteners, a reductive bleaching with a sulfinic acid derivative as a strong reductive bleach at a pH of 5.0 to 8.0 during the heating phase from 30 to 90 ° C and then bleached oxidatively in the same bath by adding hydrogen peroxide at 60 to 100 ° C within 15 to 90 minutes .
• the process according to the invention represents a rapid bleaching process and, for the first time, enables reductive and oxidative bleaching successively in a fleet.
• reducing sulfite which arises from the sulfinic acid derivatives used by redox reactions, does not disturb the bleaching effect of the hydrogen peroxide even in relatively large amounts in the weakly acidic range.
• the rapid bleaching according to the invention the bleaching results of conventional long-term bleaching are achieved or even exceeded.
• Optical brighteners absorb well on the wool under the pH and temperature conditions.
• a particular advantage lies in the combination of activators and bleaching agents, which do not require separate bleaching.
• sulfinic acid derivatives i.e. Sulphinic acid-releasing compounds used.
• Suitable for this purpose are salts of dithionic acid, such as sodium dithionite (often referred to in technical use as hydrosulfite), salts of hydroxymethane disulfonic acid, such as zinc salt of hydroxymethanesulfonic acid, or very particularly preferably thiourea dioxide (formamidine sulfinic acid).
• the sulfinic acid derivatives mentioned are advantageously used in an amount of 0.3 to 4.0 g, preferably 0.4 to 2.0, per liter of liquor.
• the ratio of wool to the liquor is usually 1:10 to 1:40, preferably 1:25 to 1:35.
• the liquor contains buffer substances with which an advantageous pH of 5.0 to 8.0, preferably 6.5 to 7.5, is set, so that the wool is attacked as little as possible.
• Suitable buffer substances are, for example, sodium hydrogen sulfite, soda, potash, sodium hydrogen carbonate or disodium hydrogen phosphate. Of these, a mixture of soda and sodium hydrogen carbonate in a ratio of 0.8: 1 to 2.1: 1 is particularly preferred.
• the expedient temperatures to be maintained for the reductive bleaching are 55 to 90 ° C., preferably between 60 and 80 ° C.
• the liquor becomes complexing agents for the calcium and magnesium ions in the water, in particular the sodium or potassium salts of nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminopentaacetic acid or, for example, hydroxyethane diphosphonic acid, diethylenetriaminepentamethylenephosphonic acid and ethylenediamine the aminotrismethylenephosphonic acid added.
• mixtures of the sodium salts of nitrilotriacetic acid or ethylenediaminetetraacetic acid with salts of hydroxiethandiphosphonic acid are used. They are preferably used in the proportions of 1: 2 to 2: 1.
• the hydrogen peroxide activators which are useful for the subsequent oxidative bleaching in particular aliphatic dicarboxylic acids, such as succinic acid, adipic acid, glutaric acid, oxalic acid, maleic acid and malonic acid, are already added to the reducing liquor. It is also possible to add the soluble alkali salts of the carboxylic acids mentioned.
• the substances used as complexing agents or activators sometimes also have a buffering effect on the pH or also function as a complexing agent or activator.
• the hydrogen sulfite formed from the sulfinic acid derivatives also regulates pH.
• the bleaching according to the invention is carried out in the usual apparatus such as reel runners or in a dyeing machine.
• the strong reducing agent is completely consumed within this time.
• the pH value drops slightly.
• reductive bleaching for example, a pH of 5.5 to 7.0, especially when working in the preferred range.
• the hydrogen peroxide is then expediently added in the form of concentrated 30 to 35% by weight aqueous solutions.
• An amount of 10 ml to 35 ml of 35% by weight aqueous hydrogen peroxide solution, preferably from 15 ml to 25 ml, per liter of liquor is advantageously used.
• the liquor ratio (weight ratio of bleaching liquor to substrate) is between 10: 1 to 40: 1.
• the actual oxidative bleaching is expediently carried out within the stated pH value from 5.5 to 7.0 at 60 to 100 ° C. within 15 to 90 minutes.
• the sodium sulfite used is not a strong reducing agent, i.e. that the sulfite for wool has practically no reductive bleaching effect.
• other additives such as detergents, e.g. Nonylphenoloxethylate with 4 to 10 ethylene oxide units, and in a particularly advantageous manner optically brightening substances, such as styrylbenzene, naphthalimide and stilbene disulfonic acid derivatives, are added.
• 100 kg of hand-knitted yarn made of pure wool in the 85 tex x 4 (Nm 12/4) spinning are bleached in a strand yarn dyeing machine in 3000 1 liquor.
• 12 kg of mixture 1 are first added to the liquor (4 g / l), then the bath is heated to 80 ° C. in 20 minutes and only then 60 l of 35% strength hydrogen peroxide (20 ml / l) are added, whereupon the bath is held at this temperature for 60 minutes and then drained. This is followed by rinsing with water and drying.
• the whiteness is 72; for the unbleached yarn it is 56.
• the same wool yarn is bleached in a traditional manner in an alkaline environment with hydrogen peroxide.
• 6 kg of tetrasodium pyrophosphate and 60 1 of hydrogen peroxide, 35% strength are added to 100 kg of yarn in 3000 l of liquor.
• the bath is heated to 45 ° C and is kept at this temperature for 5 h. Then it is drained, the wool is rinsed, dried and measured photometrically.
• the whiteness is 70.5.
• the bath is heated from 20 to 80 ° C. in 30 minutes. Then 15 l of hydrogen peroxide, 35%, are added and the treatment is continued for 45 min. It is then rinsed with water and dried. The whiteness of the bleached and optically lightened fabric is 84.
• the bath is heated from 20 to 80 ° C. in 15 minutes and held at 80 ° C. for 30 minutes, after which it is cooled, rinsed and dried.
• the whiteness of the bleached fabric is only 58, although the bleaching time and peroxide concentration were the same as in Example 4.
• 150 kg of wool sliver with an initial degree of whiteness of 58 are bleached in a dyeing machine filled with 1500 l of liquor, 6 kg (4 g / l) of mixture 4 being added first and the bath being heated to 80.degree. Then 30 1 (20 ml / l) hydrogen peroxide, 35 Xig, are added. After a further 60 min, rinsing is carried out and a sample is taken from which a whiteness of 70 is measured after drying.
• the top section is additionally reductively bleached in a fresh bath with 4.5 kg (3 g / l) sodium dithionite and 1.5 kg (1 g / l) tetrasodium pyrophosphate for 60 min at 50 ° C. After rinsing and drying, the wool has a whiteness of 76.
• Example 5 150 kg of the same sliver as in Example 5 are bleached under the same time conditions, only according to DE-PS 12 69 993, Example 1, 6 kg of the mixture mentioned there and as recommended there, 30 l of hydrogen peroxide are added at the beginning of the treatment. Heating to 80 ° C and duration of treatment correspond to example 5. The ridge has only a whiteness 65 according to the same.
• Example 5 In a fresh bath, the bleaching is just as reductive as in Example 5. The wool only reaches a whiteness of 72.5. So who achieved the bleaching effects better than those of the prior art by the process according to the invention of Example 5, even in the event that a reduction bleaching follows after the oxidation bleaching according to the known and the new process.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Detergent Compositions (AREA)

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Cited By (8)

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• 1984
  • 1984-09-15 DE DE19843433926 patent/DE3433926A1/de not_active Withdrawn
• 1985
  • 1985-09-11 DE DE8585111480T patent/DE3561211D1/de not_active Expired
  • 1985-09-11 EP EP85111480A patent/EP0175272B1/fr not_active Expired

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