CS261538B1 - A method of preparing spherical microparticles of celulfite - Google Patents

Abstract

The purpose of the method for preparing spherical cellulose microparticles is to improve the properties of cellulosic materials for separation processes. The said purpose is achieved by using an isopycnic dispersion medium containing a mixture of organic water-immiscible solvents and stabilizing the dispersion with a surfactant. An isopycnic dispersion medium containing a mixture of organic water-immiscible solvents such as carbon tetrachloride, chloroform, heptane, hexane, toluene and benzene is used. Ammonium dedodecylbenzenesulfonate, alkyl ether sulfonate and alkyl sulfonate are used as ionic surfactants. Nonionic surfactants with an HLB value of 8 to 15 can be used. The method for preparing spherical cellulose microparticles can find application in organic chemistry.

Description

261538

The invention relates to a process for preparing spherical microparticles of cellulose. The preparation of cellulose beads is based on the conventional dispersion of an aqueous solution of cellulose xanthate in liquids which are not mixed with it. Thereafter, the cellulose is re-generated from the aqueous xanthate-glucose solution by thermal coagulation (CS AO number 4.72 640).

A disadvantage of this process is the high energy intensity, the size of the cellulose obtained (above 100 [mu] m. Furthermore, a method of preparing particulate cellulose by dispersing a solution of cellulose xanthate in a liquid which is 1 to 1 with water is known). 2 g cm-3 and cellulose is regenerated by thermal coagulation (CSAO # 210 703).

The disadvantage of this method of preparation is the higher energy requirements. Regeneration of the cellulose can also be effected by eluting the xanthogenogenic groups with an excess of water of 5 to 100 ° C, preferably 70 to 100 ° C (CS AO No. 210 701).

A disadvantage of this preparation process is the problem of the elimination of washed xanthogenic groups.

Also known is a process for the recovery of precipitation acids (U.S. Pat. No. 3,597,350). The dispersing medium consists of low molecular weight solvents such as paraffinic hydrocarbons, aromatics and mixtures thereof and mineral oils.

Another method of preparing spherical cellulose based on extruding an aqueous solution of cellulose xanthate by a nozzle into a sulfuric acid solution (JP Pat. No. 7,321,738; JP Pat. No. 7,360,753).

A disadvantage of these processes is that the dimensions of the formed cellulose cellulose are relatively high above 80 µm. The aforementioned drawbacks are substantially hindered by the process of preparing spherical micro-particles of cellulose, which is based on the use of an isopycnic dispersing medium containing a mixture of organic water-immiscible solvents and stabilizing the dispersion with a surfactant. Isopycnic dispersing medium containing organic-water-non-solvent solvents such as carbon tetrachloride, chloroform, heptane, hexane, toluene and benzene is used. Asionic surfactants include ammonium dodecylbenzenesulfonate, alkyl ether sulfonate and alkyl sulfonate. Nonionic surfactants can be used in accordance with HLB 8 to 15. An advantage of the process for preparing spherical cellulose microparticles over the prior art is the economical difficulty of preparing spherical cellulose under 80 microns, simple and effective dispersion by forming a stable dispersion that allows acid cell regeneration. Example 1! An isopycnic mixture was formed from 250 mL of carbon tetrachloride, 280.8 mL of hexane and 69.2 mL of benzene. To this mixture. 600 ml add 0.5 g of a non-ionic surfactant with a 1HLB 8 value (equilibrium ratio between hydrophilic and lipophilic moiety). Then 50 ml of an aqueous solution of xanthogenate-cellulose containing 5.0 wt. % cellulose and 4.0 wt. sodium hydroxide, a density of 1.08 g / cm < 3 >, and a dispersion is formed by intensive shaking. With stirring, 10 ml of 20 wt. aqueous sulfuric acid solution. The mixture was filtered through a filter and the collected spherical microparticles were washed with 100 ml of toluene, 150 ml of 96 wt. ethanol and finally 250 ml with water. 30 g of wet micro-spherical cellulose with a dry matter content of 11.8% by weight are obtained. with dimension mi below 80 μία. iP r i k 1 and d 2

The procedure is as in Example 1 except that 0.5 ml of detergent-alkyl ether sulphate, alkyl sulphate and condensate acids (diglycol) and formaldehyde are added to the isopycnic mixture formed from 174.4 ml of carbon tetrachloride and from 425.6 ml of benzene. -dehyde (trade name · etoxone) and ammonium dodecyl benzenesulfonate. In 600 ml of this dispersion medium, dispersion is formed by vigorously shaking 50 ml of a cellulose xanthate solution. Cellulose spherical microparticles are regenerated with 14 ml of 30 wt. Acetic acid is obtained. 30 g of wet microspheric cellulose with a dry matter content of 11.7% by weight are obtained. with dimensions below 80 microns. Example 3

The procedure is as in Example 1, with the difference that 600 ml of isopycnic mixture composed of 180 ml of carbon tetrachloride, 357.4 ml of toluene and 62.6 ml of benzene are formed. 0.2 g of an alkylaryl sulfonate mixture is added. 50 ml of cellulose xanthogenate solution containing 5.0 wt. % cellulose and 4.0 wt. sodium hydroxide at 5 ° Hottenroth cooidochemical maturity. 5 ml09 wt% is added. formic acid. 30 g of wet spherical cellulose with a dry matter content of 111.8% by weight are obtained. and with dimensions below 80 μΐη

The procedure is as in Example 1 except that the isopycnic mixture is formed from 210 ml of chloroform, 79.2 ml of benzene and 310.8 ml of toluene and 0.2 g of a non-ionic surfactant with an HLB of 10 is added. The cellulose is regenerated with 10 ml of 30 wt. aqueous hydrochloric acid solution. 30 g of microspheric cellulose with a dry matter content of 11.7% by weight are obtained. with a particle size of less than 80 µm.

Claims (4)

'1. A process for preparing spherical cellulose microparticles by dispersing and stabilizing aqueous solutions of cellulose xanthate in a dispersion medium and acid recovery, characterized in that an isopycnic dispersion medium containing a mixture of organic water-immiscible solvents is used and the aqueous dispersion with surfactant is stabilized. 2. The method of claim 1 wherein isopycnic dispersing is used The medium containing a mixture of organic and water-immiscible solvents such as carbon tetrachloride, chloroform, heptane, hexane, toluene and benzene. 3. The method of claim 1 wherein ionic surfactants such as ammonium dodecylbenzenesulfonate, alkyl ether sulfonate and alkyl sulfate are used. 4. The method of claim 1, wherein said method is stabilized with a nonionic surfactant having an HLB of 8-15.