CS261538B1 - Process for preparing spherical microparticles of cellulose - Google Patents

Abstract

The purpose of the process for preparing spherical microparticles cellulose is an improvement in cellulosic properties materials for separation processes. That purpose is achieved by taking (uses isopycnic dispersing medium, (containing a mixture of organic with water with non-miscible solvents, and dispersion Stabilizes with surfactant. Isopycnic- dispersing medium containing the mixture organic water-immiscible solvents such as carbon tetrachloride, chloroform, heptane, hexane, toluene and benzene. Than ionic surfactants are used dedoceylbenzenesulfonate ammonium, alkyl ether sulfonate and alkyl sulfonate. Nonionic surfactants can be used (HLB value 8 to 15. Spherical preparation method cellulose microparticles can find use in organic chemistry.

Description

The invention relates to a process for preparing spherical cellulose microparticles.

The preparation of cellulose spheres is based on the conventional dispersion of an aqueous solution of cellulose ixanthate in liquids which do not mix with it. Thereafter, the cellulose is regenerated from aqueous solutions of cellulose xanthate by thermal coagulation (CS AO No. 172 640).

The disadvantage of this process is the high energy demand, the size of the cellulose obtained is above 1100.

It is further known to prepare a particulate cellulose by dispersing a solution of cellulose xantogemate in a liquid mixed with water at a density of 1 to 1.2 g. cm ^-3 and cellulose is regenerated by thermal coagulation (CS AO No. 210 703 j.

The disadvantage of this method of preparation is again higher energy requirements. Cellulose regeneration can also be accomplished by eluting the xanthanogen groups with an excess of water at a temperature 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 elimination of the eluted xanthogenene groups.

Also known is a method of regeneration by acid precipitation (US 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 for preparing spherical cellulose is by extruding an aqueous solution of cellulose xanthate 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 bead cellulose are relatively large above 80 µm.

¹ The above mentioned disadvantages are substantially eliminated by a process for making the microspheres of cellulose, which is characterized in that it is used isopycnic dispersion medium containing a mixture of organic water-immiscible solvents and dispereia is stabilized with a surfactant. An isopycnic dispersion medium containing a mixture of organic and water-immiscible solvents such as carbon tetrachloride, chloroform, heptane, hexane, toluene and benzene is used. Ammonium dodecylbenzenesulfonate, alkyl ether sulfonate and alkyl sulfonate are used as ionic surfactants. Nonionic surfactants with an HLB value of 8 to 15 may be used.

Advantage of the method of preparation of spherical cellulose microparticles compared to previous preparation methods is the economical difficulty of preparation of spherical cellulose below 80 μΐη, simple and efficient dispersion with the creation of a stable dispersion which allows acidic regeneration of cellulose.

Example 1! An isopylene mixture of 250 ml of carbon tetrachloride, 280.8 ml of hexane and 69.2 ml of benzene is formed. Into this mixture. 600 ml is added 0.5 g of a non-ionic surfactant having an iHLB of 8 (equilibrium ratio between hydroflin and lipophilic portion of the molecule). 50 ml of an aqueous solution of cellulose xanthate, containing 5.0 wt. % cellulose and 4.0 wt. sodium hydroxide, having a density of 1.08 g. cm- ³ and shaking vigorously to form a dispersion. 10 ml of 20 wt. aqueous sulfuric acid solution. The mixture is filtered on a filter and the collected spherical cellulose microparticles are washed with 100 ml of toluene, 150 ml of 96% by weight. ethanol and finally 250 ml with water. 30 g of wet microspheric cellulose with a dry matter content of 11.8% by weight are obtained. with dimensions mi below 80 μΐη.

iP r i k 1 and d 2

The procedure is as described in Example 1 except that 0.5 ml of alkyl ether sulfate, alkyl sulfate and fatty acid condensate and (diglycol) and formaldehyde are added to an isopycnic mixture of 174.4 ml of carbon tetrachloride and 425.6 ml of benzene. (tradename etoxone) and ammonium dodeeylbenzenesulfonate. A dispersion is formed in 600 ml of such dispersing medium by vigorously shaking 50 ml of an aqueous solution of cellulose xanthate. The spherical cellulose microparticles are regenerated with 14 ml of 30 wt. of acetic acid. 30 g of wet microspheric cellulose are obtained with a dry matter content of 11.7% by weight. with dimensions below 80 μπι.

Example 1 and d 3

The procedure is as in Example 1 except that 600 ml of an isopycnic mixture consisting of 180 ml of carbon tetrachloride, 357.4 ml of toluene and 62.6 ml of benzene are formed. 0.2 g of a mixture of alkylarylsulfonates is added. With vigorous shaking, 50 ml of an aqueous solution of cellulose xanthate, containing 5.0 wt. % cellulose and 4.0 wt. sodium hydroxide at a colloid-chemical maturity of 5 ° Hottenroth. 5 ml of 99 wt. formic acid. 30 g of wet spherical cellulose are obtained with a dry matter content of 111.8% by weight. and with dimensions below 80 μΐη. Example 4

The procedure is as in Example 1 except that the isopylene 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 having an HLB value of 10 is added thereto. 10 ml of 30 wt. aqueous hydrochloric acid solution. 30 g of microspheric cellulose are obtained with a dry matter content of 11.7% by weight. having a particle size of less than 80 µm.

Example 5

The procedure is as in Example 3 except that the isopycnic mixture is made up of 250 ml of chloroform, 207 ml of benzene and 143 ml of heptane and 0.3 g of a non-ionic surfactant having a HLB value of 10. The cellulose is regenerated with 10 g of 25 wt. aqueous phosphoric acid solution.

30 g of wet microspheric cellulose are obtained with a dry matter content of 11.7% by weight. with particle sizes less than 80 μΐη.

A process for preparing gum-like cellulose microparticles can find use in organic chemistry. The microparticles may be used directly or after physical and chemical treatment as a carrier for ion exchange, chelating and the like. functional groups.

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.