US2113906A - Bleaching process - Google Patents

Description

Patented Apr. 12, 1938 UNITED STATES PATENT OFFICE BLEACHING raocnss- No Drawing. Application March 11, 1937, Serial No. 130,417

4 Claims.

This invention relatesto bleaching processes and more particularly to a process for bleaching vegetable and animal substances, such as cotton, rayon, cellulose acetate silk and wool, either waste or raw or in yarn or piece goods.

Standard bleaching processes are relatively complicated and lengthy as, for example, the bleaching of cotton yarn, which involves substantially seven steps, as followsz-boiling in caustic, as 2% caustic soda, 1% silicate and 1% sulphonated oil or the like, dropping the above bath and washing in hot water, dropping and running through hypochlorite solution, to 2 'I'W, dropping and washing in warm water, dropping and sourlng in a hydrochloric acid or sulphurlc acid solution or the like, dropping and washing in warm water, dropping and washing in water to which is added bluing.

' without interfering with the action of the nascent oxygen.

Still another object is to provide an improved bleaching process whichwill be efficient, even if the material to be bleached contains insoluble oils.

Another object is to provide a bleaching process which will leave the material, such as rayon,

cellulose acetate silk and cotton, free of oil stains,

chafe marks andso-called niger beads.

Yet another object is to provide a bleaching process which is considerably less expensive than most standard bleaching processes for like material.

Other objects and advantages of the invention will be apparent during the course of the following detailed description thereof.

After the material has undergone any preliminary desirable treatment, such as boiling out in order to remove insoluble oils and the like, the material is treated, preferably, to a bath containing water, sodium stearate and sulphonated oil. For example, in this treatment of 100 pounds of hose having solid white bodies, heels, toes and tops, the preferred formula of this bath is:-

220 gallons water 2% sodium stearate 2% sulphonated oil said percentages being by weight and the promaterial washed, for substantially five minutes,

portion of ingredients may vary between 200 and 250 gallons water and between 2% and 3% sodium stearate and like variations in the sulphonated oil.

This treatment preferably continues for sub- 5 stantially ten minutes, with the bath at a temperature between 100 F. and 110 F. whereupon the bath may or may not be dropped and the material treated to a bath containing sodium hypochlorite and a buffer. The latter may be glues, saponified and/or emulsified fats and oils, sulphonated oils, dextrines, glucose, sugar, fatty alcohols, alkali and alkaline salts.

The sodium hypochlorite and buffer may be mixed together in substantially the following proportions:-

% by weight sodium hypochlorite 5% by weight buffer However. the percentages of sodium hypochlorite may vary between 95% and 99% while the percentages of buffer may vary between 1% and 5%.

As required, the sodium hypochlorite-buffer mixture may be employed already mixed, since it has been found that this mixture does not lose strength even after being kept for a considerable period.-

If the first bath is not dropped, from 8% to 10% by weight of the sodium hypochlorite-buiier mixture is added to it and the material treated therein for from 15 to 20 minutes. At the beginning of this last treatment, i. e., at the time the sodium hypochlorite-buifer mixture is added and the material subjected thereto, the temperature of the bath should be substantially 110 F. It 37 may be less, by allowing the first bath to cool slightly below F. to F., but it should not be over 110 F. at the start of the treatment with the sodium hypochlorite-buffer mixture. Very slowly, the temperature should be brought up to 40 between F. and t, at the close of the fifteen to twenty minute led, the temperature of the bath is between 0 F. and 180 R, whereupon the bath is dropped at once and the in a bath at a temperature between 100 F. and 110 F. which bath may comprise:-

200 to 250 gallons water 1% by weight sodium stearate (high titre) A trace bluing 50 In the event the sodium hypochlorite-buiier mixture is not added to the first bath, the latter is dropped and the material is treated to a bath containing substantiallyz- 55 200 to 250 gallons water 8% to 20% by weight sodium hypochloritebuffer mixture The treatment in. this last bath should be exactly similar to that just outlined.

After treatment as described, the material may be removed from the sodium hypochlorite-bufier mixture bath and suitably dried.

In the bleaching of mercerized cotton and rayon yarns, for example, of substantially pounds weight, the material may be boiled out for substantially five mimaes in a bath containing:

200 to 250 gallons water 2% by weight trisodium phosphate 4% by weight soda ash 2% byweight sodium stearate (such as green soap 145) whereupon, the bath is dropped and the material treated to a bath containing substantially:-

100 to 250 gallons water 2% by weight trisodium phosphate 2% by weight sodium stearate (such as green soap 145) 10% by weight mixture It is preferred that, at the start, this bath be at a temperature of substantially 100 F. and maintained at that temperature for about fifteen minutes, whereupon the bath is brought to a boil and boiling maintained for twenty minutes, after which the bath is dropped and the material rinsed in a bath containing about:-

100 to 250 gallons water 2% sodium stearate If and as required bluing For bleaching raw stock. cotton, the same is, preferably, treated by boilling for one hour in a 5% caustic soda bath, and is then given a hot rinse (180 F. to boiling) for substantially onehalf hour after which it is introducedto a bath which includesz- 2% soda ash 1% sodium stearate 8% sodium hypochlorite-bufier mixture sodium hypochlorite-bufi'er In this treatment of raw stock cotton, the bath tially as follows for 100 pounds hose. A bath is prepared comprising substantially?- 200 to 250 gallons water 2% 110.3% sodium stearate 2% to 3% sulphonated oil The material is treated in this bath, with the latter at a temperature between 100 F. and F. for a period of substantially ten minutes whereupon there is added between 8% to 10% of the sodium hypochlorite-bufler mixture and treatment continued for from fifteen to twenty minutes, whereupon the temperature is raised to, preferably, 180' F. to 190 F. (altho this temperature may vary between F. and 190 F.) The higher temperature range is maintained for about twelve minutes after which the bath is dropped and fresh water of between 200 and 250 gallons containing from 1% to 2% sodium stearate (high titre), with bluing if desired, is employed as a rinse, the rinse being maintained at a temperature of from 100 F. to 110 F. over a mriod of substantially five minutes, whereupon the surplus may be extracted and the material dried.

In the treatment of material with acetate figures, such as hose, 100 pounds of such material may be treated to:

200 to 250 gallons water 2% to 3% sodium stearate 2% to 3% sulphonated oil This treatment may continue for substantially ten minutes at from 100 F. to 110 F. after which acetate dyes may be added and treatment continued for substantially thirty minutes at a temperature varying between F. and F. At the expiration of this period the bath is dropped and fresh water added at a temperature of between 100 F. and 110 F., the water containing substantially 1% sodium stearate and 8% to 10% sodium hypochlorite-buher mixture. The material is maintained in this bleaching bath for substantially fifteen minutes with the temperature of the bath at between 100 F. and110 F whereupon the temperature is increased, over a period of substantially fifteen minutes to about 170 F. after which this treatment is discontinued. the bath dropped, and fresh water at about 110 Fa employed as a rinse, this water containing about 1% sodium stearate to 200 to 250 gallons of water. A period of between five and ten .w utes will be sufiicient to remove all surplus dyes.

With the treatment described, the chlorine does not attack the material being bleached, due to the proportions of bufiers employed and the temperatures maintained.

Various changes may be made to the forms of the invention herein described, without departing from the spirit of the invention or the scope of the claims.

What isclaimed is:

1. In a bleabhing process for containing material, the steps subjecting said material over a ten and twenty minutes to a bath containing sodium hypochlorite and a buffer, said bath being at a temperature between 100 F. and 110 F., and subsequently bringing the temperature of said bath up to between 140 F. and the boiling temperature of said bath over a. period of between twelve minutes and forty-five minutes, and dropping said bath, said bath being the sole major bleaching step of said process.

2. In a bleaching process for fibrous cellulose which consist in of freeing said material of stains, chafe marks and so-called niger beads thereon, which consist period of between rayon, cotton, cellulose acetate silks and like material, the steps in subjecting said material over a period of between ten and twenty minutes to a bath consisting of sodium hypochlorite, a buffer and water, said bath being at a temperature of between 100 F. and 110 F., and subsequently graduallyincreasing this temperature over a period -of between fifteen and twenty minutes until the temperature reaches between 160 F. and F. and immediately separating said material and said 3. A bleaching process for rayon, cotton, cellulose acetate silks and like material, which consists in subjecting said material over a period of between ten and twenty minutes to a bath consisting 0! water, sodium steal-ate and sulphonated oil at a temperature oi between F. and.110 E, dropping said bath, and subuquently subiecting said material to a bath containing sodium lrypochlorite and a buffer at a temperature of substantially It, bringing said second bath, over a period of between iiiteen and twenty minutes, to a temperature of between 180 F. and 180 R, dr pping said bath, and washing said material.

4. A bleaching process for fibrous cellulose material containing acetate figures, which consists in treating said material to a bath comprising water, sodium stearate and sulphonated oil for substantially ten minutes at a temperature between 100 1". and 110 F., adding acetate dyes, increasing said temperature to between F. and F., maintaining said temperature for substantially thirty minutes. dropping said bath, and treating said material to a bath comprising water, sodium stearate. sodium hypochlorite and a butler at a temperature between 100 F. and 110 F. for substantially fifteen minutes, slowly increasing said temperature, over a period of substantially iliteen minutes, to substantially 170 F., and immediately dropping said bath.

EDWIN P. SHERMAN.