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
  • D06L1/00—Dry-cleaning or washing fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods
  • D06L1/12—Dry-cleaning or washing fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods using aqueous solvents
  • D06L1/14—De-sizing

Definitions

• the invention relates to a process for desizing cotton or cotton-containing fabrics in strongly alkaline solutions with alkali hypochlorite in the presence of an activator for hypochlorite and the use of activators for hypochlorite for desizing in strongly alkaline aqueous solutions.
• the warp threads are sized in order to be able to weave cotton fabrics and cotton-polyester blends without any problems.
• starch-containing sizing agents are usually used, which are also frequently used with semi-synthetic sizing agents, such as carboxymethyl cellulose and synthetic sizing agents, e.g. Polyvinyl alcohol or polyacrylates can be mixed.
• the tissues are desized by breaking down the starch and then washing out the breakdown products.
• the starch can be degraded, for example, enzymatically or oxidatively in an alkaline or soda-alkaline medium with persulfates and bromite.
• hypochlorite for bleaching for desized tissues.
• a pH of 11 to 12 is generally maintained and, in order to avoid fiber damage at these pH values, at which the hypochlorite is active depending on the pH value, the shortest possible residence times must be observed.
• the desizing process according to the invention is advantageously carried out in the strongly alkaline range, corresponding to a content of 15 to 150 g, preferably 25 to 70 g of sodium hydroxide / 1 water and at room temperatures, at temperatures of 10 to 55 ° C. with an amount of alkali metal hypochlorite, in particular sodium hypochlorite, the second up to 8 g, preferably 2 to 4 g of active chlorine.
• the residence time is 2 to 24 hours and of course depends on the temperature and the amount of active chlorine used.
• a bleaching effect is simultaneously produced in the desizing according to the invention
• Cotton-containing fabric is to be understood as meaning fabric mixtures of at least 30% cotton, in particular cotton with polyester.
• the activators which can be used according to the invention and are soluble in the strongly alkaline aqueous solution are: tertiary trishydroxyalkylamines having 2 or 3 carbon atoms in alkyl, such as triethanolamine, bis-hydroxyethyl-hydroxypropylamine, trishydroxypropylamine, oxethylated and / or oxpropylated ethylenediamines with a total of 4 to 10 ethylene oxide and / or propylene oxide units, such as N, N'-tetra-hydroxyethyl-ethylenediamine, N, N'-tetrahydroxypropyl-ethylenediamine, urea derivatives, such as N, N'-tetramethylurea, N, N'-tetrahydroxiethyl urea, N, N'-dimethylethylene urea, N, N'-bis-hydroxyethyl ethylene urea, propylene urea, N, N'-dimethyl propy
• Cyanuric acid derivatives such as trishydroxyethyl and trishydroxy propyl melamine and 2,4,6-trishydroxylamine triazine.
• Cyanuric acid, oxazolidone-2, N-methylpyrrolidone-2 and N-methylimidazole are particularly preferred as activators.
• the preferred amounts of activator for the hypochlorite are 3 to 5 g / l.
• the additives according to the invention act in a surprising and unpredictable manner as activators for the hypochlorite, which is normally deactivated in the strongly alkaline aqueous medium. These additives only result in a relatively short residence time for the tissue under the oxidative action of hypochlorite. The risk of tissue damage is significantly reduced. At the same time, the fabric is bleached and the remains of the husk of the cotton are largely removed.
• the new process can be carried out with good effect at room temperature, around 20 ° C, in an energy-saving manner.
• the bleaching effect and the removal of seed husks from the cotton without additional heat treatment are the particular advantages to be emphasized in comparison to the enzymatic desizing.
• Oxidative desizing with persulfate a clear bleaching effect is not achieved when it is carried out as a residence process at room temperatures. The removal of the cotton seed husks is insufficient. Oxidative desizing with persulfates is therefore carried out in practice as a hot treatment.
• wetting agents, detergents and other customary auxiliaries which must of course be stable to hypochlorite, can be added in a manner known per se.
• These additives are known to the person skilled in the art and generally serve to make the desizing process more reliable in its course. This also includes the use of sequestering and dispersing agents when washing out the tissues.
• the activating effect of the additives on a strongly alkaline hypochlorite solution was determined by the decrease in the active chlorine content of the solutions over time.
• the respective active chlorine content was determined titrimetrically with sodium thiosulfate.
• Test conditions 20 ° C, 5 g / 1 active chlorine, 40 g / l NaOH
• the alkaline hypochlorite solutions are used to desize cotton fabrics made from polyester / cotton blended fabrics.
• the fabric pieces are soaked in desizing liquor, squeezed to 100% liquor absorption and left to linger. In all cases, the tissues are washed out immediately after treatment.
• the degree of whiteness, the desizing (according to the Tegewa scale) and also the DP value (average degree of polymerization) of the cellulose are determined from these pieces of fabric.
• composition of the desizing liquor 40 g / 1 NaOH, 5 g / 1 active chlorine, 3 g / 1 nonylphenyloxethilate, 2 g / 1 wetting agent (phosphoric acid ester).
• Residence time 5 hours residence temperature: 45 ° C
• Residence time 5 hours, residence temperature: 45 ° C.
• Example 2 For comparison, an experiment according to Example 2 is carried out without addition of hypochlorite and without catalyst.
• Residence time 16 hours residence temperature: 45 ° C liquor absorption: 80%
• the fabric according to Example 4 is desized enzymatically.
• Residence time 3 hours residence temperature: 75 ° C
• the fabric is then bleached according to example 4, but using 4 times the amount of hydrogen peroxide compared to example 4.
• Residence time 10 minutes residence temperature: 100 to 102 ° C liquor absorption: 100%

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Detergent Compositions (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Woven Fabrics (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)
• Absorbent Articles And Supports Therefor (AREA)

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Applications Claiming Priority (2)

Publications (3)

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ID=6224879

Family Applications (1)

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Cited By (2)

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Citations (1)

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• 1984
  • 1984-01-13 DE DE19843400989 patent/DE3400989A1/de not_active Withdrawn
  • 1984-12-15 AT AT84115524T patent/ATE43872T1/de not_active IP Right Cessation
  • 1984-12-15 DE DE8484115524T patent/DE3478623D1/de not_active Expired
  • 1984-12-15 EP EP84115524A patent/EP0151284B1/fr not_active Expired
• 1985
  • 1985-01-11 US US06/690,522 patent/US4654043A/en not_active Expired - Fee Related
  • 1985-01-11 ES ES539497A patent/ES539497A0/es active Granted

Patent Citations (1)

Non-Patent Citations (3)

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