SU414339A1 - METHOD OF BLEACHING CELLULOSE - Google Patents

Description

This invention relates to methods for bleaching pulp materials and can be used in the pulp and paper industry.

There is a known method of bleaching (refining) cellulose by treating it with π1 molecules in an alkaline medium at elevated temperature and pressure in the presence of magnesium compounds. However, an increase in the alkali concentration leads to an increase in the oxidative degradation of cellulose due to a decrease in the protective effect of the magnet compounds.

In order to reduce the following: oxidative destruction of cellulose, a process has been proposed in the absence of addition of three atrio phosphate 1 or more of B, 0.02–3.5% by weight of the fiber.

The introduction of three 1-in. Yphosphate without compounds also exerts a protective de: -stepia, but to a lesser degree than their compatibility.

Example 1. Sulfate unbleached wood pine pulp with a stiffness of 105 lane manganate units was bleached from molecular oxygen with a direct pressure of 1 kg to 10 kgf / cm, a temperature of 115 ° С, and a consumption of caustic soda 6.0% of the weight of the piece, in the absence of (in the amount of 0.05% Mg by weight of fiber) for 60 minutes with the addition of 1.0% by weight of fiber and phosphate.

For srav1e and cellulose bleached from to salsdo in the same conditions, about three to one third of Yphosphate, with the addition of atyphosphate,

without. and also in the absence of

 additives.

The indicator of white cellulose and 1 cellulose carrying oxygen (O-1-cell bleaching (see)) in the table .. 1.

T a b l i and a 1

Nebelin integer.-polo.cha

0.05 I and 05 I

.39.5

842

212

25 27 24 26

fiS, 7,160 67.7 69, i 149 69.5 1 11

It follows from the data obtained that the introduction of trisodium phosphate makes it possible to obtain cellulose with a higher viscosity than in the presence of magnesium compounds alone, and even more so when bleaching with oxygen in the absence of additives.

Example 2. The same unbleached sulphate pulp is bleached with molecular oxygen at an oxygen pressure of 10 kgf / cm-, temperature 115 C, caustic soda consumption 4.0% by weight of the fiber, in the presence of magnesium compounds (in an amount of 0.05% Mg2 + by weight fiber) for 60 minutes with the addition of 0.5 by weight of trisodium phosphate fiber and without it.

Subject invention

Claims (2)

1. A method of bleaching pulp by treating it with oxygen in an alkaline medium at elevated temperature and pressure in the presence of magnesium compounds, characterized in that For comparison, the pulp is also bleached in the absence of any additives and in the presence of trisodium phosphate alone. The results of bleaching are shown in Table. 2 The table shows that the addition of trisodium phosphate to magnesium compounds reduces the oxidative destruction of cellulose, i.e. increase the viscosity of the pulp produced to 333 MPZ against 273 when bleaching is carried out in the presence of only magnesium compounds and 217 in the case of oxygen-base bleaching without additives. Addition of one trisodium phosphate (experiment 3) allows to increase the viscosity of cellulose up to 255 MPa. table 2 in order to reduce the oxidative degradation of cellulose, the process is carried out in the presence of trisodium phosphate. 2. A method according to claim 1, characterized in that trisodium phosphate is added in an amount of 0.02-3.5% by weight of the fiber.