DE420684C - Process for rapid bleaching of all types of vegetable fiber - Google Patents

Description

Process for rapid bleaching of all types of vegetable fiber Es it is known to impregnate fiber material with bleaching solutions and after impregnation has taken place to remove the excess bleach by mechanical means, a Ventilation of the bleached goods is achieved. In this process, however, are only thin Bleach solutions have been used in the case of using hypochlorite solutions Do not tend to contain more than t g of chlorine per liter. Stronger bleach solutions «- are generally considered to be detrimental to the strength of the fiber material.

It has now been found, surprisingly. that you are highly concentrated Bleach solutions, which in the case of hypochlorite solutions .2o g chlorine and more each Liters, can achieve very good bleaching without fiber damage, if, as in the above-mentioned method, the material is immediately after complete saturation with the bleaching solution (with admission of air) by mechanical means from the excess freed of the solution. The bleaching then takes place so quickly that during the damage to the bleached goods does not occur for a short period of time. You can do the bleach Accelerate further by preheating the goods to be bleached, for example with hot `wet 'or Steam or by preheating the bleach or by subsequent treatment of the already saturated and thrown off goods with steam or with steam Air. You can also add small amounts of carbonic acid to this air and so on by reducing the alkalinity of the bleach solution, as is known, speeding it up achieve. The time saved with such bleaching is considerable. You can be average get along with '1 = 0 to' Iäo of the bleaching times used up to now.

The procedure can be carried out in various ways, Depending on the soaking with bleach, a squeezing, a suction or makes a hurl. It turned out that the work in the centrifuge runs particularly advantageous. One can proceed as follows, for example.

The pulp to be bleached is left as a thin fiber pulp in a When the centrifuge is running slowly, it injects into the Centrifuge hot water until the bleached material has reached a temperature of 3o to 4o ° has, whereupon with uniform sprinkling of the slowly rotating in the centrifuge Fiber-good strong chlorine lime solution of, for example, 30 g of chlorine per liter is injected will. The bleaching solution that drains off is returned to the spin basket for as long as until the desired degree of bleaching is achieved, followed by warm and cold water washed, possibly acidified and washed again.

Claims (1)

PATENT CLAIMS: i. Process for rapid bleaching of vegetable Fiber material of any kind, characterized in that it is mixed with a strong bleaching liquid, which contain at least 10 g of chlorine per liter in the case of the use of chlorinated lime solution must, impregnated fiber material immediately after impregnation by mechanical force (Centrifuging, squeezing, suction) freed from excess bleach and by suitable devices, preferably in the centrifuge, for temporary or constant ventilation. z. Method according to claim i, characterized in that that the increase in concentration achievable after i and thus increased bleaching effect by heating the bleaching agent or the items to be bleached or both, for example by blowing it in accelerated by steam or warm air. 3. Method according to claim i characterized in that the air flow used for venting is accelerated Initiation of the bleaching process adds small amounts of carbonic acid.