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
  • D06L4/20—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen
  • D06L4/22—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen using inorganic agents
  • D06L4/23—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen using inorganic agents using hypohalogenites
• • 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
  • D06L4/20—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen
  • D06L4/21—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using agents which contain halogen combined with specific additives

Definitions

• Cotton fabrics and blends containing cotton are bleached in the textile industry mainly with hydrogen peroxide or with hypochlorite. Under certain circumstances, both bleaching processes are used in succession.
• Hypochlorite bleaching is usually carried out at room temperatures of 20 to 25 * C and a pH of 9.5 to 12.
• the duration of the treatment varies between about 20 minutes and several hours, depending on the amount of active chlorine used.
• hypochlorite has a more or less damaging effect on cotton fibers.
• handbook of textile auxiliaries by Chwala / Angerer, Verlag Chemie, Weinheim-New York, 1977, pages 343/344 clearly shows that in technical textile bleaching with sodium hypochlorite at temperatures of at most 35 * C and within a pH Range of 9.5 to 12 must be worked to keep the fiber damage as low as possible. Increasing the temperature by 10 ° C causes the bleaching speed to double, but it also causes greater fiber damage.
• hypochlorite bleach can be combined with a subsequent hydrogen peroxide bleach in order to obtain a special degree of whiteness and high absorbency.
• the alkaline peroxide solution first removes the remaining hypochlorous acid, the chloramines formed from accompanying substances in the cotton, in order to then develop their actual bleaching effect. Fiber protection agents are essential.
• the object of the invention is to demonstrate a bleaching process with hypochlorite which can be carried out at higher temperatures.
• the invention lies in the combination of hypochlorite or hypochlorite-releasing compounds with an easily oxidizable substance and the unforeseeable effect lies in particular in the fact that higher alkali concentrations, for example from 8 to 60 g / l sodium hydroxide, can be used as previously, without the fibers are damaged and the bleaching effect is not lost.
• Cotton-containing fabric is to be understood as meaning pure cotton and in particular polyester blended fabric with a cotton content of at least 20%. Of course, the corresponding yarns are also included.
• Alkali hypochlorite in particular sodium hypochlorite, and also compounds which split off hypochlorite, such as dichloro- and trichloroisocyanurate, are used as hypochlorite.
• the bleaching liquors contain 1 to 8, preferably 2 to 6 g of active chlorine / 1 or the amount that this amount of active chlorine can release.
• N is the alkaline aqueous liquors according to the inventive bleaching proceed advantageously have a pH of at least 10 degrees.
• This pH range is expediently set by adding alkali metal hydroxide, in particular sodium hydroxide, generally in an amount of 8 to 60 g / 1, preferably 10 to 25 g / 1.
• the liquors optionally contain 5 to 15 g / 1 alkali carbonate, preferably sodium carbonate.
• the entire fleet is generally advantageously about 100% by weight, based on the weight of the fabric.
• a special feature of the method according to the invention is that it is carried out at temperatures from 80 to 110 ° C.
• the preferred temperature range is from 90 to 103 ° C.
• Another special feature is the implementation of the bleaching process in the presence of a water-soluble polyhydroxy compound which is stable to hypochlorite in the cold and at room temperature and easily oxidized in the heat, i.e. with the hypochlorite reacts faster than this with the cellulose units of the cotton.
• polyhydroxy compounds with an ⁇ -hydroxycarbonyl group from the series of mono-, di- and oligosaccharides and the series of o-hydroxycarboxylic acids and their derivatives are outstandingly suitable.
• Polyols such as mannitol, sorbitol, glucitol, glycerol and polyglycerol, and mucochloric acid can also be used.
• Particularly preferred polyhydroxy compounds to be used according to the invention are glucose, cane sugar and hydroxyacetone.
• the polyhydroxy compounds are added to the bleaching liquors in an amount of 0.5 to 20 g / 1, preferably 1.5 to 10 g / 1.
• the term easily oxidizable is intended to encompass the gradations relatively stable in the cold to hypochlorite and increasing redox potential with increasing alkali concentration and increasing temperature. It is only through this interaction that work can be carried out in the temperature range according to the invention, which was previously not accessible for an industrial textile bleaching process.
• a particularly noteworthy advantage is that in the bleaching process according to the invention the active chlorine has a very short half-life. As a rule, all active chlorine is used up within the temperature range according to the invention after one minute and is no longer detectable even on the tissue.
• the method according to the invention is advantageously carried out within 30 seconds to 25 minutes, preferably 1 to 5 minutes.
• the short half-life has the advantage that, for example when the machine is at a standstill, no damage to the tissue can occur due to a longer oxidation time.
• peroxides there is no need for stabilization measures, as are usual with peroxides, and a much lower sensitivity to contamination should be emphasized with heavy metal.
• the customary additives such as the addition of surfactants as wetting agents and detergents, are advantageously used in an amount of 3.0 to 10 g / l and of which alkylphenol ethoxylates with 5 to 10 ethylene oxide units and fatty alcohol ethoxylates with approximately the same degree of ethoxylation are particularly mentioned be.
• additives relate, for example, to the sequestering agents which are stable to oxidation because of the water hardness and which can additionally increase the whiteness. Hydroxyethane diphosphonic acid is particularly suitable for this.
• the tissue pieces were enzymatically desized and then washed out.
• the next pre-treatment step is an alkaline decoction (conditions: 40 g / 1 NaOH, 10 g / 1 decoction aid, liquor absorption: 100 X, time and temperature: 10 minutes at 100 ° C).
• the fabric pieces were then soaked in bleaching liquor and squeezed to a liquor intake of 100%.
• Polyester / cotton fabric (50/50), desized and boiled with a Tegewa value of 7 to 8, a whiteness of 71.5 (Elrepho units) and a DP value of 2100.
• Bleaching liquor 10 g sodium hydroxide / l, 5 g / 1 surfactant, 2.5 g / 1 active chlorine in the form of sodium hypochlorite.
• Treatment time 2 minutes at 100 ° C.
• Bleaching liquor 10 g sodium hydroxide / 1.5 g / 1 surfactant, 3.0 g / 1 active chlorine in the form of dichloroisocyanate.
• Treatment time 2 minutes at 103 ° C.
• Treatment time 3 minutes at 100 ° C.
• Cotton shirt poplin desized (Tegewa value 7-8) and boiled, with a whiteness of 70.5 and a DP value of 2500.
• Bleaching liquor 8.5 g / 1 NaOH, 5 g / 1 surfactant, 2.5 g / 1 active chlorine in the form of sodium hypochlorite, 3.5 g / 1 glucose.
• Cotton raincoat poplin desized (Tegewa value: 6-7), boiled, with a whiteness of 68 and a DP value of 2220.
• Bleaching liquor 15 g / 1 NaOH, 7 g / 1 surfactant, 4 g / 1 active chlorine in the form of chlorine solution, 6 g / l maltose.
• Treatment time 90 seconds at 103 ° C.
• Cotton nettle desized (Tegewa value: 7), boiled, with a whiteness of 69 and a DP value of 2320.
• Bleaching liquor 10 g / 1 NaOH, 7 g / l surfactant, 3 g / 1 active chlorine in the form of chlorine bleach.
• Treatment time 1 minute at 101 ° C.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Detergent Compositions (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

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• 1984
  • 1984-05-16 DE DE19843418109 patent/DE3418109A1/de not_active Withdrawn
• 1985
  • 1985-04-23 AT AT85104913T patent/ATE41957T1/de not_active IP Right Cessation
  • 1985-04-23 EP EP85104913A patent/EP0164534B1/fr not_active Expired
  • 1985-04-23 DE DE8585104913T patent/DE3569270D1/de not_active Expired
  • 1985-05-03 US US06/730,095 patent/US4622037A/en not_active Expired - Fee Related

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