SU405991A1 - - Google Patents

Description

one

This invention relates to a method for bleaching fibrous semi-finished products, a "cellulose, hemicellulose and woody Miaiccbi.

There is a known method of bleaching volcious semifinished products by ablating them with alkaline (pacTBOpoiM hydrogen peroxide in the presence of a stabilizer decomposing hydrogen peroxide and alcohol, for example isopropyl, as an organic additive (reagent.

Odpa. By a known method with a large consumption of alcohol (for example, 20% by weight of absolute dry fiber) get the target product with a whiteness of 72.5%.

For the purpose of improving the procession, an arganic reagent is proposed in zhes-cheshve (Use acyclic ester keto "s in an amount of 0.02-2% of (weight of absolute dry fiber).

Acyclic saturated ketones, for example, aceto.n, to the interaction of s alkaline solution of hydrogen peroxide with polyatomic phenols, in, the course of the schIl1m: and in the composition of lignip, and also with extra active substances, contribute to the corresponding hydroperoxide which in alkaline medium decompose into simpler compound-and with the formation of intermediate peroxide radicals, deepening the processes of o-acidification and, most likely, contribute to the formation of esters, hydrolyzing to colorless acids. In this way, the whiteness of the fibrous semi-finished products increases.

Example 1. 100 g of unbleached sulfite pulp with a whiteness of 59.6% (determined on a Zeiss meter according to GOST 7690-66) are bleached with hydrogen peroxide. The bleaching solution contains 2.5% hydrogen prizes From a weight of absolutely dry, 3.5% silicate "Atri IB (Weed liquid glass with a specific weight of 1.41 -1.43 g / cm N 1.5% caustic soda (pH 10.0-10.5). Temperature: 55-60 ° C, and long-term. The temperature is 3 hours.

1.7% acetone is added to the bleaching solution before it is transported with the cellulose.

After bleaching, the cellulose is washed with water to neutralize the washing water, treated with the following solution with an acid solution, washed until neutral and dried. The degree of whiteness of the pulp after bleaching is 74.1% (increase in the degree of whiteness during the finishing process by 14.5%).

The same pulp is bleached under similar conditions without addition to bleaching

acetone solution, has a whiteness of 71.4%.

When bleaching pulp in the specified

conditions, but with (using bleaching

solution, in the cocraiB kotoroto instead of 1.7% acetone, put 20% (by weight of absolutely dry

fibers) from OIR OLI of left alcohol, whiteness 72.5%.

Example 2. Unbleached sulphite pulp with a whiteness of 61.5% (.o.nipe ", Eleno, as in example 1) is bleached with peroxide

hydrogen under the same conditions as in 1P | p: and, at least 1, added various ketones to the whitening solution. The results are given in the table.

From the data given in the table, it follows that the degree of whiteness of the pulp increases already: and addition; In IB ke whitening pacTBiOp. Minimum 1KOL1Istestnaya keto "o.v - 0.02% of iBecia a1 absolutely dry fiber. The maximum begins with the introduction of K-etones in the amount of 0.5-1.7% by weight of absolutely dry fiber. Introduction .more than 2%. Keto. Because it is not so much, as the additional increase of 1 degree of whiteness is not 1 on dish.

PRI dm e t inventions

The method of bleaching fibrous semi-finished products of the first treatment of their treatment with an alkaline solution of hydrogen peroxide in the presence of stabilizing Topia decomposition of hydrogen peroxide and the addition of an organic reagent, characterized in that acyclic saturated ketones are used in the process improvement layer. 0.02-2% by weight of absolutely dry fiber.