The method of obtaining cellulose

 

(57) Abstract:

The method relates to the production of cellulose for paper made from softwood timber and belongs to the pulp and paper industry. The cellulose raw material on the basis of coniferous wood is subjected to cooking sulfite cooking solution when the pH of the solution of 1.65-2,00, the content is just SO2in the specified solution of 8.5-9.5% and a temperature of 143-146S. Resulting mass is washed and treated with a mixture of potassium fluoride, hydrogen peroxide and oxalic acid at a ratio of components. The sulfite cooking cooking solution is performed on sodium, magnesium, and mixed sodium-magnesium base at a ratio of NaO2and MgO is 1:1 and processing the washed pulp is carried out at a temperature of 75-85C, the flow of the mixture of potassium fluoride, hydrogen peroxide and oxalic acid of 0.8-1.2% by weight of the absolutely dry fibers and mass concentration of 6-8%. The technical result is to obtain a soft pulp while maintaining high mechanical strength, high belmosto environmentally friendly reagents. 2 C.p. f-crystals, 1 table.

The invention relates to the pulp and paper industry and can be used when production is the overall cooking cellulose-containing raw material sulfite cooking solution (SU, 1654400, class D 21 3/10, 07.06.91).

The cooking is carried out at pH sulfite pulping solution of 2.1-2.4, the content is just SO2in the specified solution of 4.3-5.5% and a temperature of 151-S on magnesium (MgO - 1,25-1.6 per cent), and as the cellulose-containing raw material use coniferous wood.

Obtained in a known manner cellulose is of limited use in the production of newsprint due to low white (to 66.5%). Thus obtained in a known manner cellulose is characterized by high stiffness (Kappa number, 29,4-66,7) that does not allow you to whiten her on chlorine-free schemes bleaching.

A method of obtaining cellulose, including cooking cellulose-containing raw material sulfite cooking solution on a mixed magnesium-sodium base at a ratio of MgO and PA2About from 1:1 to 1:4 and the subsequent bleaching bleaching reagent (EN 2106448, class D 21 3/06, 10.03.98).

The cooking is carried out at pH sulfite pulping solution of 1,8-2,15, the content is just SO2in the specified solution of 5.1-5.4% and a temperature of 148-S, and as the cellulose-containing raw material use of coniferous wood. The obtained cellulose, characterized by the Kappa number, 18, is subjected to bleaching by the scheme X-S-X-S-G-GK is characterized by high viscosity at high content of cellulose. The use of such cellulose paper production is impractical.

The closest analogue of the present invention is a method of producing cellulose comprising melting a cellulose-containing raw material on the basis of softwood sulfite cooking solution (EN 2010068, class D 21 3/06, 30.03.94).

The cooking is carried out at pH sulfite pulping solution of 2,5-3,4, content just SO2in the specified solution of 5.5-7.5% and a temperature of 152-S, and as the cellulose-containing raw material, a mixture of wood of larch and spruce. The cooking is carried out on sodium (Na2O=2,5-3,5%) or magnesium (MgO=1.7 to 2.3%) basis.

Obtained by a known method, the cellulose is characterized by the following parameters: high output, white - (51,0-62,0%) and relatively high strength.

However, reduced white (not more 62,0%) limits the range of paper where you can use such as cellulose, and high hardness pulp (Kappa number, more of 31.8) does not allow to obtain good results when bleaching by chlorine-free schemes bleaching.

The technical result of the proposed method is to obtain a soft pulp with increasing mechanical strength, characterized by the t, however, in the method of producing cellulose comprising melting a cellulose-containing raw material on the basis of softwood sulfite cooking solution according to the invention the cooking is carried out at pH sulfite pulping solution of 1.65-2,00, the content is just SO2in the specified solution of 8.5-9.5% and a temperature of 143-146S, and after cooking the mass is washed and treated with a mixture of potassium fluoride, hydrogen peroxide and oxalic acid at a ratio of these components in a mixture (wt.%): fluoride potassium 59-69 (in Russian), hydrogen peroxide 28-38 and oxalic acid - the rest.

The sulfite cooking cooking solution is performed on sodium, magnesium, and mixed sodium-magnesium base at a ratio of Na2O and MgO is 1:1, and processing the washed pulp is carried out at a temperature of 75-85C, the flow of the mixture of potassium fluoride, hydrogen peroxide and oxalic acid of 0.8-1.2% by weight of the absolutely dry fibers and mass concentration of 6-8%.

In the proposed method, as the cellulose-containing raw material on the basis of coniferous wood use spruce wood, as well as a mixture of potassium fluoride, hydrogen peroxide and oxalic acid is used disinfectant “Fanmades” (registration certificate №R No. 0503-59/5-2002 from 10.06.2002, this tool is intended for disinfection of surfaces in premises, sanitary-technical equipment, laboratory and household utensils, clothes and medical products made of corrosion-resistant metals, rubbers and plastics.

The “Fanmades” tablets of white color, odorless, soluble in water, aqueous solutions are clear, colorless. Shelf life means is 2 years at a storage temperature of +5C to +30C.

The inventors found that the combination of the specified cooking cellulose-containing raw material, followed by processing the resulting pulp means “Fanmades” can significantly improve the whiteness index of cellulose in stage 1 processing perekonnasisesi tool and its low flow rate of about 10 kg/so

It is established that the conduct of cooking under these conditions - elevated concentrations of SO2, low pH and temperature, allows to obtain a soft pulp with Kappa number, 10-24, which is bleached without the use of chloropropanol organic reagent “Fanmades”, used in medicine as a disinfectant, in one step and at a flow rate of 8-10 kg/t to white 78-80%.

the keys as follows: 1000 g of absolutely dry spruce wood chips are loaded into the autoclave and pour the boiling solution of sodium base, having a pH of 1.65 and content SO28,5%. Perform temperature rise to S during 3,0 hours and are cooking for a 2.0 hours. After cooking, the pulp is washed and treated with vehicle “Fanmades”, which is a mixture of hydrogen peroxide 28%, potassium fluoride 69% and oxalic acid 3%. Process conditions: temperature 80 ° C, the concentration of mass - 7%, consumption “Fanmades” - 1% to absolutely dry fiber, the processing time is 3.0 hours, the pH of 11.0, which is achieved by adding NaOH in the amount of 1% to absolutely dry fiber.

The Kappa number after cooking is 15,0. The whiteness of the pulp after bleaching was 78.5%.

Indicators of the quality of the pulp are shown in table.

Example 2. The method of producing cellulose magnesium base is carried out, as in example 1 with the only difference that use cooking solution with a pH of 2.0 and content just SO29.5%, and the cooking is carried out at a temperature of 146S for 1 hour 30 minutes, the treatment of pulp is carried out, as in example 1 means “Fanmades” of the following composition: hydrogen peroxide 38%, potassium fluoride 59%, oxalic acid 3%. Pulp after cooking is characterized by the Kappa number, 23, white pulp after treatment 80,0%.

Pok is magnesium-sodium base at a ratio of MgO:Na2O 1:1 is carried out, as in example 1 with the cooking solution containing 8.5% of all the SO2having a pH of 1.8 at a temperature S for 2.5 hours. Treatment is carried out as in example 1 means “Fanmades” of the following composition: hydrogen peroxide 38%, and the potassium fluoride is 60.5%, oxalic acid and 1.5%. Pulp after cooking is characterized by the following indicators: the Kappa number of pulp - 10,0, white after processing is 81%.

Indicators of the quality of the pulp are shown in table.

Example 4 (the prototype).

The method of obtaining cellulose is as follows: fir wood chips in the amount of 1000 g load in the autoclave and pour sulfite cooking solution of magnesium base having a pH of 2.5, the content is just SO2of 7.5%, MgO of 2.3%, the cooking is carried out at a temperature IS in a period of 3.0 hours. The Kappa number of the pulp after cooking 45,7, white 62%.

Indicators of the quality of the pulp are shown in table.

Example 5 (control).

The method of obtaining cellulose carried out analogously to example 4 with the only difference that the resulting mass after cooking is treated with a mixture of hydrogen peroxide, potassium fluoride and oxalic acid at a ratio of these components in a mixture (wt.%):

Indicators of the quality of the pulp are shown in table.

The analysis of the table shows that the proposed method allows to obtain a pulp with a higher brightness at 16-18% (abs.) and higher mechanical strength. This pulp without additional bleaching suitable for the production of writing and printing paper types.

Thus, the claimed technical result of the proposed method is achieved by a combination of the stated cooking and processing new bleaching reagent.

1. The method of producing cellulose comprising melting a cellulose-containing raw material on the basis of softwood sulfite cooking solution, characterized in that the cooking is carried out at pH sulfite pulping solution of 1.65-2,00, the content is just SO2in the specified solution of 8.5-9.5% and a temperature of 143-146S, and after cooking the resulting mass is washed and treated with a mixture of potassium fluoride, hydrogen peroxide and oxalic acid at a ratio of these components in the mixture, wt.%:

Fluoride potassium 59-69 (in Russian)

Hydrogen peroxide 28-38

Save spend on sodium, magnesium and mixed sodium-magnesium base at a ratio of Na2O and MgO is 1:1.

3. The method according to p. 1, wherein processing the washed pulp is carried out at a temperature of 75-85C, the flow of the mixture of potassium fluoride, hydrogen peroxide and oxalic acid of 0.8-1.2% by weight of the absolutely dry fibers and mass concentration of 6-8%.

 

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FIELD: paper-and-pulp industry.

SUBSTANCE: process of producing high-refined cellulose for manufacture of man-made fibers and films comprises water or acid pre-hydrolysis of disintegrated vegetable material followed by delignification of pre-hydrolyzed wood by way of catalyzed peroxide pulping and alkali extraction of oxidized lignin at atmospheric pressure. Final operations are bleaching and alkali refining of cellulose.

EFFECT: improved quality of cellulose, improved environmental safety of process, and reduced power consumption.

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