JPH02235944A - Preparation of porous particles of both cellulose and cellulose derivative - Google Patents

Abstract

PURPOSE:To prepare cellulose (deriv.) particles with a uniform porosity by a simple process by emulsifying a watery soln. of cellulose (deriv.) in an org. solvent soln. of a thickening polymer, adding the resulting emulsion to an org. solvent which is miscible with water but does not dissolve cellulose, and allowing the resulting mixture to cool. CONSTITUTION:A 1-20%, pref. 3-12%, watery soln. of cellulose or a deriv. there of (e.g. carboxymethylcellulose) having a viscosity of 300 to 10,000cps, pref. 1,500 to 5,000cps, is emulsified in an org. solvent soln. of a thickening polymer (e.g. a chloroform soln. of polyvinylpyrrolidone) pref. in the presence of 1-7%, pref. 1-3%, (based on said watery soln.) nonionic surfactant such as polyoxymethylene ricinoleate. Pref. vol. ratio of said watery soln. to said org. solvent soln. is (1:1) to (1:1.4). The resulting emulsion is cooled to 40 deg.C or lower, added to an org. cooling solvent which is miscible with water but does not dissolve cellulose, and the resulting mixture is allowed to cool to room temp., thus giving porous cellulose particles.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a novel method for producing spherical porous particles made of cellulose and cellulose derivatives.

<Prior art> For example, granules of cellulose or its derivatives used as carriers for various chromatography such as gel chromatography and ion exchange chromatography are porous particles with a certain shape, especially spherical shape. This is required.

Conventionally, the following method can be cited as an example of manufacturing this type of cellulose particles.

First, cellulose is converted into an organic solvent-soluble derivative, such as cellulose acetate, and this is dissolved in a water-insoluble organic solvent, such as chloroform.

This chloroform solution of cellulose acetate is suspended in water thickened with polyvinyl alcohol (PVA), etc.
Porous beads of cellulose acetate are obtained by stirring and evaporating chloroform while maintaining the temperature at a temperature higher than the boiling point of chloroform for a long time.

Next, the acetyl groups are saponified to form cellulose beads.

However, the method of evaporating the solvent by heating takes time.

In addition, cellulose derivatives having heat-sensitive functional groups, such as cyanoethyl cellulose, carbamoyl cellulose, and cellulose xanthate in alkali dopes, have the disadvantage that they are susceptible to deterioration during the bead synthesis process.

On the other hand, in the production of cellulose derivative particles, it is common to once create cellulose particles as described above, and then carboxymethylate the surface or introduce other functional groups.

However, subsequent chemical modification does not increase the degree of reactivity and only a portion of the surface is modified due to the introduction of functional groups.

Further, during the reaction, the surface portion swells and porosity is inhibited.

<Problems to be solved by the present invention> Conventional methods for producing cellulose and cellulose derivative particles have complicated and time-consuming synthesis routes, making it difficult to form particles of thermally unstable derivatives and to synthesize uniform porous particles. It is.

An object of the present invention is to provide a method for producing cellulose and cellulose derivative particles that does not have such drawbacks.

<Means for Solving the Problems> An object of the present invention is to emulsify an aqueous solution of cellulose or a cellulose derivative by adding it to an organic solvent containing a thickening polymer, and to raise the emulsion temperature to 40°C.
C. or less, the emulsion is poured into a cooled organic solvent in which cellulose or a cellulose derivative is insoluble and soluble in water, and the emulsion is allowed to stand at room temperature.

That is, an emulsion of cellulose or a cellulose derivative is cooled in a water-soluble organic solvent in which the derivative is insoluble,
Uniform porous particles are obtained by dehydration.

In the present invention, the cellulose derivative used as a raw material for porous particles may be any commonly used water-soluble cellulose derivative, and representative examples include carboxymethyl cellulose, carboxyethyl cellulose, carbamoylethyl cellulose, cellulose acetate, methyl cellulose, ethyl cellulose, Examples include hydroxypropyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cellulose xanthate, aminoethyl cellulose, diethylaminoethyl cellulose, triethylaminoethyl cellulose and sulfoethyl cellulose.

An aqueous solution is prepared by dissolving the cellulose or cellulose derivative in the most soluble aqueous medium, either pure water, an acidic or alkaline aqueous solution.

Concentration of cellulose or cellulose derivatives is 1-20%
, preferably 3 to 12%, and the viscosity is 300 to 1
0000 cps, especially 1500 to 5000 cps is preferred.

This aqueous solution of cellulose or a cellulose derivative is added to an organic solvent thickened with a polymer to emulsify it.

For emulsification, it is desirable to add 1 to 7%, preferably 1 to 3%, of a nonionic surfactant such as a polyoxymethylene adduct of sinoleic acid to the aqueous solution of cellulose or cellulose derivative.

The combination of an organic solvent and a polymer for thickening the organic solvent is not particularly limited, but preferred typical examples include those shown in the table below. The mixing ratio of the viscous organic solvent is preferably in the range of cellulose aqueous solution:organic solvent=1:0.7 to 1:1O, particularly 1:1 to 1:4 in terms of volume ratio.

This emulsion is stirred at a predetermined stirring speed and cooled if necessary.

The emulsion temperature may be any temperature below 40° C., and it is preferable to stir the emulsion at a predetermined temperature for 30 minutes or more.

Subsequently, the emulsion was cooled with an organic solvent (-30℃~=
-0℃) and leave to warm to room temperature while stirring gently.

The mixing ratio of the emulsion and the organic solvent is 1/0 by volume.
It is sufficient if it is 5 or more.

The organic solvent used here is l) freely miscible with water;
2) mixes freely with the organic solvent used during emulsion preparation, 3) dissolves the thickening polymer, and 4)
Those in which cellulose or cellulose derivatives are insoluble are suitable.

Examples of organic solvents that meet these conditions include methanol, ethanol, dimethylformamide (
For (2), methanol, DMF, D
MSO, especially methanol, and for (3) acetone are preferably used.

A process in which particles of cellulose or cellulose derivatives are formed by injecting an emulsion of cellulose or cellulose derivatives into a cooled water-soluble organic solvent in which they are insoluble, and the water inside the particles is eluted little by little into the organic solvent for dehydration. As a result, uniform porous particles are formed.

Temperature and volume of cellulose emulsion,
It is desirable to tightly control four factors: temperature and volume of the cooled organic solvent.

That is, the porous state of the resulting particles changes slightly depending on the temperature conditions of the emulsion and the organic solvent.

This is because, if the temperature changes, the rate at which water in the particles dissolves into the organic phase and the state of phase separation between the polymer and the solution will also change.

In this case, the heat of mixing and heat of dilution accompanying mixing of the emulsion and the organic solvent must be taken into consideration.

Therefore, by strictly controlling the above four factors, the same porous state can be achieved with good reproducibility.

More specifically, the temperature of the emano region and the temperature of the organic solvent affect the porosity of the resulting particles.

For example, when an emulsion cooled to -20°C is added to an organic solvent at -20°C, the resulting beads have fine pores on their surfaces.

Conversely, when an emulsion at +25°C is poured into an organic solvent at -20°C, beads with a larger pore size than the former are obtained.

After filtering the porous particles thus formed, the polymer used for thickening is removed by washing, followed by washing with a solvent such as metal or ether, dehydration, and drying to obtain the final product. It will be done.

When using isolated porous particles in an aqueous system, it is necessary to perform water insolubilization treatment by crosslinking, which involves reaction in an organic solvent using shrimp chlorohydrin, a bisepoxide compound, a dichloride compound, etc. It may be processed according to known methods.

Furthermore, when cellulose xanthate is used as a derivative, spherical porous particles of cellulose can be obtained by regeneration using a weak acid.

<Function> In the method for producing porous cellulose or cellulose derivative particles of the present invention, any cellulose or cellulose derivative that is soluble in an aqueous medium, that is, water, an acid, or an aqueous alkali solution, can be suitably used as a raw material. can.

Unlike conventional methods, cellulose derivatives can be used that have been delocalized by introducing various functional groups in advance, and do not require heat treatment, so there is no risk of deterioration and uniform porosity. Spherical particles with .

Formation of porous spherical particles can be carried out in a short time by an extremely simple process of cooling and dehydrating an emulsion of cellulose or a cellulose derivative in the above-mentioned water-soluble organic solvent.

The particle size and porosity can be easily adjusted by changing the concentration of cellulose or cellulose derivative, emulsification conditions, temperature and time of cooling and dehydration, stirring speed, etc.

<Example> Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1) Pulp was immersed in a 17.5% aqueous sodium hydroxide solution at room temperature for 1 hour, and then squeezed to 2.8 times the original weight of the pulp.

This was pulverized to produce alkali cellulose powder, which was used in the production of cellulose derivatives.

550 ml of 9% aqueous sodium hydroxide solution was added to 100 g of this alkali cellulose powder to form a slurry.

Furthermore, 30 g of acrylonitrile (cellulose/acrylonitrile) -1/3 (mole ratio) was added and reacted for 1 hour to obtain a yellow transparent viscous aqueous solution.

15 ml of polyoxyethylene ricinoleate was added as a surfactant to 500 ml of this viscous solution.

On the other hand, as an oil layer, 90 g of polyvinylbilolibin (PVP) (K-30 manufactured by Hayashi Pure Chemical Industries, Ltd.) was mixed with 20 g of chloroform.
A solution uniformly dissolved in 0On+I was used.

550 ml of the polymer solution and 770 ml of chloroform thickened with PVP were mixed, and the emulsion was cooled to -20°C while stirring at a stirring speed of 400 rpm.
It was held for a minute.

Subsequently, 1980 ml of MeOH cooled to -10°C
The solution was gradually poured into the solution and left to stand at room temperature.

The supernatant was removed by decantation, washed thoroughly with methanol and then with ether, filtered through a glass filter, and dried under vacuum.

(a) For crosslinking treatment: Suspend the above dried beads in a dimethyl sulfoxide/acetone mixed solvent, add a predetermined amount of shrimp chlorohydrin, and react with gentle shaking at 60°C for 24 hours to perform crosslinking. (method of Honsato et al., Journal of the Chemical Society of Japan, No.
9, 1187 (1988)).

The beads were filtered from the reaction solution, washed with methanol, and then diluted with methanol/0.1%}12sO4 until the washing solution became acidic.
Washed with H20: (5/1) solution.

Thereafter, it was washed with methanol 820: (3/1), washed with methanol and then with ether, and then dried under vacuum.

(b) In the case of no crosslinking After the cooling and dehydration process, the heat in methanol was filtered off at room temperature.

This was mixed with 9% H2SO4 methanol/H20: (1
0/l) solution, methanol and then ether, dried in vacuo and stored on silica gel.

Example 2) 100 g of the alkali cellulose used in Example 1 was placed in an eggplant-shaped flask, and the pressure was reduced using an aspirator.

64.4 g of propylene oxide (6 times the mole relative to cellulose) was added to this, and the mixture was left to stand for 18 hours.

200g of the obtained hydroxypropyl cellulose
% NaOH aqueous solution (polymer concentration 13%).

Using this dope, hydroxypropylcellulose beads were obtained in the same manner as in Example 1.

Example 3) Hiscose for the production of soap (cellulose content 9.5%, sodium hydroxide concentration 5.5%, γ value 4El52) 120
Emulsify 0ml in 1750ml of PVP thickened chloroform in the same manner as in Example 1. Cool at -20°C for 30 minutes).

This was poured into 4000 ml of methanol at -20°C.

Under cooling, acetic acid was added to a concentration of 1% based on methanol, and the mixture was gently stirred to regenerate cellulose.

After standing at room temperature, this was thoroughly washed with water, methanol, and then ether to obtain beads.

Electron micrographs of the obtained beads are shown in Figures 1 to 3 (30, 100, and 5000 times magnification).

<Effects of the present invention> As explained above, according to the present invention, cellulose and cellulose derivative particles having uniform porosity can be produced using a general water-soluble cellulose derivative as a raw material through a simple synthesis route. .

[Brief explanation of drawings]

Figures 1 to 3 are electron micrographs of cellulose beads obtained in Example 3 (30, 100, 500,
0 times). Procedural amendment 7. Contents of the amendment The description of "Brief explanation of the drawings" is revised as follows. Patent Application No. 1-55151 2. Name of the Invention Process for Producing Porous Cellulose and Cellulose Derivative Particles Figures 1 to 3 are electron micrographs (30, 1
00,5000 times). ”3. Relationship with the case of the person making the amendment

Claims (8)

[Claims] (1) An aqueous solution of cellulose or a cellulose derivative is added to an organic solvent containing a thickening polymer to emulsify it, the emulsion temperature is set to 40°C or less, and the emulsion is prepared so that the cellulose or cellulose derivative is insoluble and soluble in water. A method for producing porous cellulose and cellulose derivative particles, which comprises injecting the particles into a cooled organic solvent and allowing the particles to stand until room temperature. (2) The production method according to claim (1), wherein the cellulose derivative is a water-soluble cellulose derivative that is soluble in water, an acidic or alkaline aqueous solution. (3) The water-soluble cellulose derivative is carboxymethylcellulose, carboxyethylcellulose, carbamoylethylcellulose, cellulose acetate, methylcellulose, ethylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, ethylhydroxyethylcellulose, hydroxypropylmethylcellulose, cellulose xanthate, aminoethylcellulose, diethylaminoethylcellulose, The method according to claim 1, wherein the cellulose is selected from the group consisting of triethylaminoethylcellulose and sulfoethylcellulose. (4) The method of claim (1), wherein the aqueous solution of cellulose or cellulose derivative has a concentration of 1 to 20%. (5) A claim in which a nonionic surfactant is added to emulsify an aqueous solution of cellulose or a cellulose derivative (
1) Manufacturing method. (6) The temperature of the organic solvent into which the emulsion is added is 0℃~
The manufacturing method according to claim (1), wherein the temperature is in the range of -30°C. (7) The manufacturing method according to claim (1), wherein the mixing ratio of the emulsion and the organic solvent is set to a volume ratio of 1/0.5 or more. (8) Add an aqueous solution of cellulose or a cellulose derivative to an organic solvent containing a thickening polymer to emulsify it, bring the emulsion temperature to 40°C or less, and then cool the emulsion to a solution in which the cellulose derivative is insoluble and soluble in water. A method for producing porous cellulose and cellulose derivative particles, the method comprising: injecting the particles into an organic solvent, leaving the cells up to room temperature, filtering out the generated cellulose or cellulose derivative particles, and subjecting the particles to the necessary water insolubilization treatment. .