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
  • D06L4/30—Bleaching fibres, filaments, threads, yarns, fabrics, feathers or made-up fibrous goods; Bleaching leather or furs using reducing agents
• • 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

Definitions

• This invention relates to "the treatment of textiles; and it comprises an improvement in the bleaching of bast fibers such as linen, jute, hemp and the like with p eutral hyp ochlo 'te followed by alkaline hydrogen peroxidefthe 'iniprsvemene being that the unbleached bast fibers are submitted to a preliminary treatment with a reducing material, usually a sulphite, prior to treating with hypochlorite and alkaline peroxide; all as more fully hereinafter set forth and as claimed.
• solubility number furnishes a measure of the amount of the material soluble in caustic soda solutions under closely specified conditions, and since it is mainly the chemically degraded cellulose that dissolves under these conditions, high solubility numbers are associated with severe degradation and low numbers with but slight attack.
• the conditions and method of determining solubility numbers are set out in a paper by C. R. Nodder in The Journal of the Textile Institute 1931, 22, T. 416.
• This invention has as an object to devise an improved process of bleaching bast fiber material.
• a still further object is to devise a method whereby an optimum white can be obtained for any given solubility number.
• a still further object is to provide bast fiber material having a better white in relation to solubility number than has hitherto been possible. Further objects will appear hereinafter. These objects are accomplished by the following invention.
• the reducing agent may be an alkaline sulphite; that is, a solution of S02 with somewhat more alkali than is necessary to form a neutral sulphite.
• alkaline sulphite that is, a solution of S02 with somewhat more alkali than is necessary to form a neutral sulphite.
• Other reducing agents such as hyposulphite, zinc formaldehyde sulphoxylate, etc., may be used.
• the present invention consists in the improvement or modification of the process of application Serial No. 183,396 in which the bast fiber materials are treated with a solution of a reducing agent prior to the treatment with the neutral hypochlorite solution.
• the introduction of this treatment does not preclude other treatments such as the usual preliminary steep or boil in an alkaline liquor, e. g. soda ash solution.
• alkali metal and alkaline earth metal sulphites As reducing agents capable of being used in the process are alkali metal and alkaline earth metal sulphites, bisulphites, and hyposulphites and the corresponding acids. More particularly we have found that the sodium salts of sulphurous acid, sodium sulphite and sodium bisulphite are cheap and convenient reducing agents for use in the process and consequently we shall describe the process in greater detail with reference to these salts as applied to linen.
• a bisulphite When a bisulphite is added to an alkaline material it is of course con verted into a sulphite and if the goods are alkaline from the use of an alkaline liquor, the alkali present may sufiice for converting a bisulphite into a sulphite.
• the goods should be Well washed before being treated with the hypochlorite solution.
• hypochlorite solution e. g. sodium or calcium hypochlorite
• a suitable hypochlorite solution e. g. sodium or calcium hypochlorite
• a salt having the required buffer characteristics more particularly sodium bicarbonate.
• the conditions of the use of such a hypochlorite solution are also described in detail and it is stated that in order to obtain satisfactory bleaching while avoiding damage to the cellulose the available chlorine concentration should be within the limits 1.5 and 5.0 grams per litre.
• the amount of buffer salt added may be varied to some extent in accordance with the concentration of available chlorine, but in general a liquor containing before use between 2.5 and 3.5 grams of available chlorine, and 8 grams of sodium bicarbonate per litre, will be found applicable for most purposes.
• the source of the hypochlorite is to a large extent immaterial and in most cases it will be found that a solution prepared by the usual methods from bleaching powder is applicable.
• the hypochlorite solution should be applied with the substantial exclusion of actinic rays.
• the temperature should not be higher than 20 C. and preferably not higher than 15 C.
• the time of treatment may be varied considerably, but for the solutions containing about 3.0 or more grams of available chlorine per litre mentioned above, we find that half an hour should preferably not be exceeded.
• sour should advantageously be applied cold and may be of any strength normally applied to cellulosic fibres.
• Sulphuric acidv may be used but it is preferable to use a hydrochloric acid sour when the hypochlorite bath has been made up from bleaching powder. The risk of calcium sulphate remaining on the fibre due to its relatively low solubility is thereby avoided.
• the goods are thoroughly washed in cold water and then treated in an alkaline solution and with an oxidising bleaching agent.
• This treatment may comprise two stages such as a plain treatment at an elevated temperature With an alkaline solution, followed by a hydrogen peroxide solution.
• a plain treatment at an elevated temperature With an alkaline solution, followed by a hydrogen peroxide solution.
• we combine the alkali and oxidising bleaching treatment by using an alkaline solution containing hydrogen peroxide.
• the peroxide bath may be prepared by diluting a strong hydrogen peroxide solution with water and adding a suitable alkali.
• a strong hydrogen peroxide solution with water and adding a suitable alkali.
• Other additions as have been mentioned in connection with the bath made from sodium peroxide may also be made.
• concentrations of the alkali and peroxide in the liquor are capable of being varied within very wide limits, while still enabling very good whites to be attained and avoiding undue attack on the material.
• Example 1 A batch of linen yarn was treated for one hour at 70 C. in fifteen times its weight of liquor containing 0.65% soda ash and 0.35% sodium sulphite (NazSOs) and washed well first in warm and then in cold water.
• the hanks were transferred to a reeling machine and treated for thirty minutes in a neutral hypochlorite liquor prepared by diluting a strong solution of bleaching powder and adding sodium bicarbonate.
• the initial available chlorine content of the liquor was 3.0 grams per litre and the sodium bicarbonate used was 5 grams per litre. Reeling was done between 15 and 16 C. in the dark. After reeling the yarn was rinsed in cold water, soured in 0.5% hydrochloric acid and well washed.
• the yarn was then bleached for two hours at 65 C. in a liquor containing 0.2% sodium peroxide, 0.24% concentrated sulphuric acid (168 Tw.) and 0.3% sodium silicate solution (100 Tw.), washed and dried.
• the yarn was a good half white, in fact, approaching three-quarters white, and had a solubility number 3.9.
• Example 2 A small lot of linen yarn was thoroughly Wet out, treated at C. for one hour in a liquor containing 0.5% sodium bisulphite and washed thoroughly. The yarn was then treated in a neutral hypochlorite liquor, rinsed, soured, washed, bleached in peroxide liquor, washed off and dried precisely as in Example 1.
• the reducing agent treatment can be used with or without an alkaline steep or boil.
• an alkali treatment it is preferable that the linen to be bleached is thoroughly wetted out prior to the treatment with the solution of the reducing agent. This may quite easily be done by means of water containing a small amount of a known wetting out agent such as Turkey red oil.
• the solution of reducing agent When used in conjunction with an alkali treatment, it may precede or follow it, or the two treatments may be combined. Except in the case of a combined reducing agent-alkali treatment the conditions of concentration, temperature and time, which have been outlined above apply. When the reducing agent is used in conjunction with the alkali in a single bath we find it is better to allow a longer treatment time, say at least one hour, but in respect of concentration of reducing agent and temperature the conditions are the same.
• sodium sulphite and bisulphite used in the above examples we could have used any of the soluble sulphites, bisulphites or hyposulphites of the following metals: sodium, potassium, lithium, calcium, barium, strontium, zinc, magnesium or beryllium, sulphurous acid or any other sulphur containing acid which is a reducing HUUUU agent.
• Compounds of the type of zinc formaldehyde sulp-hoxylate may also be used.
• This invention is a valuable advance in the art as by its use we can again improve the process that we disclosed in Serial No. 183,396. As is shown by the examples we can get finer bleaching and at the same time preserve the fibre to the same extent.
• the improved process which comprises first contacting the unbleached material with alkaline aqueous solution of a sulphite containing between 0.1 per cent to 0.5 per cent of sulphite and maintaining said solution at a temperature between and C.
• a substantially neutral hypochlorite solution having a pH value between 6 and 8 and containing between 1.5 and 5 grams per liter of available chlorine and sufiicient buffer compound to maintain the pH value within said range during said contact, at a temperature not exceeding 20 C.

Landscapes

• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Inorganic Chemistry (AREA)
• Detergent Compositions (AREA)
• Paper (AREA)
• Chemical Or Physical Treatment Of Fibers (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=10083847

Family Applications (1)

Country Status (4)

Cited By (4)

• 0
  • NL NL88338D patent/NL88338C/xx active
• 1937
  • 1937-06-16 GB GB16798/37A patent/GB497346A/en not_active Expired
• 1938
  • 1938-06-10 US US213076A patent/US2202334A/en not_active Expired - Lifetime
  • 1938-06-16 FR FR839349D patent/FR839349A/fr not_active Expired

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