EA024244B1 - Process for producing cellulose powder - Google Patents

Abstract

The use: a process for producing cellulose powder can be used in chemical, pharmaceutical, food and other branches of industry. The essence of the invention: the process for producing cellulose powder is carried out by soaking crushed cellulose with an aqueous potassium pyrosulphate solution for 90-180 min with molar ratio water:potassium pyrosulphate:cellulose, drying with further milling, which results in obtaining flowing cellulose powder with high reactivity and the yield up to 97.25 wt.%.

Description

The invention relates to the chemistry of cellulose, and in particular to a method for producing powdered cellulose, which may find application in chemical, pharmaceutical, food and other industries.

A known method of producing powdered cellulose. As raw materials, cellulose and sulfuric acid are used. Cellulose at a temperature of 90 ° C for 2 hours is treated with a 5% solution of sulfuric acid, the ratio of cellulose to sulfuric acid is 1:10, respectively. The resulting cellulose solution is filtered, neutralized at a temperature of 120-160 ° C, and in the second stage at a temperature of 100-120 ° C [1].

The disadvantage of this method is the activation of cellulose by chemical reagents at high temperature to produce wastewater.

There is a known method of activating cellulose by treating with Lewis acids A1C1 ₃ and T1C1 ₄ in the presence of solvents CC1 ₄ , SCM, C ₂ H ₅ OH, the concentration of Lewis acid in solution is 0.01-1.5%. After activation, the degree of polymerization of the obtained cellulose powder is 80-120, which is half the value of the specific degree of polymerization for microcrystalline cellulose obtained by classical hydrolysis. It was shown that based on powder cellulose obtained using T1C1 ₄ and having a low degree of polymerization, the synthesis of soluble sulfate derivatives with a high degree of substitution is possible [2].

The disadvantage of this method is the activation of cellulose with chemicals in the presence of solvents to produce wastewater.

A known method of producing reactive cellulose containing 90% alpha-cellulose, crushed cellulose with a particle size of 1.3 x 1.3 cm is placed in a double wall autoclave. Liquid ammonia is introduced under pressure through a shutter in the autoclave. The system is heated to a temperature of 10 ° C, maintaining an autoclave pressure of 20 bar for 60 s. After this, the pulp is transferred through the shutter to the explosive reactor. At the gate opening, the pressure of ammonia in the cellulose drops rapidly, and the sudden evaporation of ammonia of a kind of explosion leads to the destruction of cellulose fibers. After this, the pulp is transferred through the shutter to the explosive reactor. The concentration of ammonia in the pulp due to the use of reduced pressure is reduced to a value below 0.2% by weight of the pulp.

Ammonia-activated cellulose, characterized by a residual mass concentration of ammonia, is neutralized in a solution of caustic soda (400 ml of solution per 10 g of cellulose). Modified cellulose is squeezed and washed with ethanol to remove alkali [3, prototype].

The disadvantages of the method are the activation of cellulose using chemicals, the process under pressure, the use of a neutralizing agent and washing with alcohol, the formation of wastewater.

The objective of the invention is to expand the range of inorganic reagents used in the activation of cellulose, and the development of environmentally friendly technology for the activation of cellulose.

The problem is solved by treatment of cellulose by impregnation with an aqueous solution of potassium pyrosulphate acid for 3 hours at a molar ratio of water: pyrosulphate potassium: cellulose equal to 15.4416.44: 0.0157-0.0866: 0.0185, respectively, by filtration and drying at a temperature of 100-105 ° C for 60 minutes, followed by grinding for 4-8 minutes, the result is a free flowing cellulose powder with a particle size of 10-320 microns, with high reactivity, yield up to 97.25 wt.%.

The proposed method for the activation of cellulose in comparison with the prototype is that to maximize the fragility of the macromolecular structure of the cellulose, it is treated with aqueous solutions of pyrosulphate potassium followed by filtration and drying before milling and, when milled, the macromolecular and fibrous structure is destroyed to obtain a loose cellulose powder with a high reactivity. The content of the main fraction with a particle size of 10320 μm and the yield is 97.25 wt.%. (According to the prototype, to activate cellulose, it is treated with liquid ammonia at a pressure of 20 bar at a temperature of 10 ° C for 60 s. After the cellulose is transferred to an explosive reactor and the ammonia pressure is sharply reduced, causing a kind of explosion and destruction of cellulose fibers in the cellulose, neutralization is carried out activated cellulose with sodium hydroxide solution and washing with ethyl alcohol. Cellulose activation is accompanied by wastewater). The proposed method for the activation of cellulose is an environmentally friendly process.

For a better understanding of the invention, the following are examples.

Example 1

In a liter beaker equipped with a stirrer, 296 g (16.44 mol) of distilled water, 4 g (0.0157 mol) of pyro-sulfuric potassium are loaded and the stirrer is turned on at a speed of 60 rpm, to the resulting aqueous solution of pyro-sulfuric potassium 3 g (0.0185 mol) of pulped pulp. Cellulose treatment is continued for 180 minutes, and then, at a temperature of 100-105 ° C., drying is carried out for 60 minutes, the subsequent grinding of the treated pulp is 8 minutes. The resulting loose cellulose powder is fractionated with sieves. The molar ratio of water: pyrosulphate potassium: cellulose is 16.44: 0.157: 0.0185, respectively.

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The results of the experiments are presented in the table.

The quality of pyrosulphuric acid potassium is determined by GOST 7172-65, the composition of cellulose is GOST 5982-82, GOST 6940-78, the fractional composition of activated cellulose powder is GOST 3584-73, the dry residue of the copolymers is determined by the physicochemical method, the hydrogen number of solutions is determined by pH- meter.

Example 2

Carried out as in example 1, except that using 291 g (16.1 mol) of distilled water and 9 g (0.0354 mol) of pyrosulphuric acid potassium. The molar ratio of water: potassium pyrosulphate: cellulose is 16.1: 0.0354: 0.0185, respectively.

Example 3

Carried out according to example 1, except that using 296 g (16.44 mol) of distilled water and 12 g (0.0472 mol) of potassium pyrosulphuric acid. The molar ratio of water: potassium pyrosulphate: cellulose is 16.44: 0.0472: 0.0185, respectively.

Example 4

Carried out as in example 2, except that using 284 g (15.7 mol) of distilled water and 16 g (0.062 mol) of pyrosulphuric acid potassium. The molar ratio of water: potassium pyrosulphate: cellulose is 15.7: 0.062: 0.0185, respectively.

Example 5

Carried out according to example 2, except that using 278 g (15.44 mol) of distilled water and 22 g (0.0866 mol) of pyrosulphuric acid potassium. The molar ratio of water: potassium pyrosulphate: cellulose is 15.44: 0.0866: 0.0185, respectively.

Example 6

It is carried out according to example 1, except that the pulp processing time is 120 minutes and the grinding time is 4 minutes.

The molar ratio of water: pyrosulphate potassium: cellulose is 16.44: 0.0157: 0.0185, respectively.

Example 7

It is carried out according to example 2, except that the pulp processing time is 90 minutes and the grinding time is 8 minutes.

The molar ratio of water: pyrosulphate potassium: cellulose is 16.44: 0.0157: 0.0185, respectively.

The experiments show that the treatment of cellulose with an aqueous solution of potassium sulfuric acid potassium, followed by filtration and drying at a temperature of 100-105 ° C, ensures that the cellulose acquires maximum brittleness and, when milled, the macromolecular and fibrous structure is destroyed to obtain a loose cellulose powder with high reactivity.

Λ » Name of reagents Numbers of experiments and their results one 2 3 4 5 6 7 Taken one Distilled water, column 296 291 288 284 278 296 291 2 Potassium sulfate, column 4.0 9.0 12 16,0 22.0 4.0 9.0 3 Pulp amount, gr 3.0 3.0 3 3.0 3.0 3.0 3.0 4 Pulp processing time, MIN 180 180 180 180 180 120 90 5 Drying at a temperature of 100-405 ’C min 60 60 60 60 60 60 60 6 Grinding time min 8 8 8 8 8 4 8 RECEIVED 7 Cellulose powder ..... T 2.76 2.77 2.84 2.82 2.89 2.78 2.75 8 Fractional composition of the powder: % 630 μm 11.52 7.52 3.4 3,5 2.05 9.75 25.10 320 μm 38.40 36.62 21.09 20.79 19.65 36.72 55.72 200 microns 25.78 27.41 36.92 37.51 38,42 26,20 10.50 100 μm 19.15 22.60 30.72 30.83 31.18 23.82 8.68 50 microns 3.65 4.05 5.64 5.57 6.60 3.31 10 microns 1,5 1.80 2.23 2.00 2.10 0.20 nine pH-aqueous dispersions of powder one 6.6 6.7 6.8 6.8 6.65 6.7 6.6 10 Cellulose powder yield, % 87.53 92.48 96.60 96.70 97.25 90.25 74.90

Literature

1. Patent 20684419 Russia, IPC С08В 15/02, publ. 10/27/1999

2. Abstract. dis. for a job. student step. Cand. Chem. sciences. Frolova S.V. (Institute of Chemistry of Komi, Scientific Center Ur ORAN, 167610 Komi Republic. Syktyvkar, 48 Pervomaiskaya St.). Arkhang. Gos. tech. University, Arkhangelsk, 2008, 20 pp., ill. Bible 18. Rus.

3. Application 99124792 Russia, IPC С08В 1/02, published on 04.20.2003.

Claims (1)

CLAIM The method of obtaining activated cellulose, including the processing of cellulose with liquid ammonia, characterized in that in order to impart maximum fragility of the macromolecular structure of cellulose, before grinding, it is treated with aqueous solutions of potassium pyrosulfuric acid for 90180 minutes at a molar ratio of water: potassium sulphate: potassium: 15 , 4416.44: 0,0157-0.0866: 0.0185 respectively, followed by filtration and drying at a temperature of 100105 ° C for 60 minutes and grinding for 4-8 minutes, a free-flowing powder with high reaction concentration was obtained individuality, particle size 10-320 microns, to yield 97.25 wt.%.