JPH054139B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for producing an anion exchanger using granular porous chitosan as a carrier.
It is suitable for many uses such as a carrier for immobilizing a biocatalyst and a carrier for cell culture. [Prior Art] In recent years, continuous automation of reaction processes using catalytic action has been progressing in the enzyme/cell utilization industry. In such processes, various ion exchangers are used, but while the carrier is packed in a column or tank and used, clogging occurs or the carrier itself is destroyed, causing the reaction solution to deteriorate. There is a drawback that distribution cannot be carried out smoothly, and improvements to the carrier are being considered to overcome this problem, but the situation is still insufficient. As a method for producing an anion exchanger using chitin or chitosan as a carrier, for example,
Proposal No. 35180 has been made. The method disclosed in this publication involves using chitin or chitosan itself as a raw material and contacting it with an aqueous alkali solution, and then bonding it with an organic halide having a substituted or unsubstituted amino group or a substituted quaternary ammonium group to form an anion exchanger. As is clear from Examples, the ion exchange capacity of the anion exchanger obtained is only about 0.8 meq/g, and when used as a carrier for enzyme immobilization, the ion exchange capacity of the anion exchanger obtained is This method has the drawbacks of extremely low adsorption amount and poor catalytic efficiency, and when used as a cell culture carrier, charge control is required depending on the cells used. The anion exchanger thus obtained has the disadvantage that it swells or dissolves due to acid or alkali during treatment. [Problems to be Solved by the Invention] An object of the present invention is to provide a method for producing a chitosan-based anion exchanger that solves the above-mentioned conventional drawbacks. The present invention uses low molecular weight chitosan to obtain granular porous chitosan with uniform particle size and uniform micropores on the spherical surface and cut surface, and further cross-links this by contact with an organic diisocyanate compound in a polar solvent. By using this material, the ion exchange ability can be significantly improved compared to chitosan-based anion exchangers obtained by conventional methods, and the ability can be freely adjusted.
A chitosan-based anion exchanger that has sufficient physical strength, does not swell or dissolve in acidic and alkaline solutions, and can be used in a wide range of ion exchange capacities is produced, thereby solving the above-mentioned conventional drawbacks. This is the solution. [Means for Solving the Problems] The present invention involves dissolving low molecular weight chitosan in an acidic aqueous solution and dropping the dissolved solution into a basic solution. Relates to a method for producing an anion exchanger characterized by contacting and crosslinking with a compound, then contacting with a basic solution, and then reacting with an organic halide having a substituted or unsubstituted amino group or a substituted quaternary ammonium group. . In the present invention, the average molecular weight is from 10,000 to
230,000 low molecular weight chitosan is used. High-quality chitosan having a desired molecular weight can be obtained by heating flaky high-molecular-weight chitosan in an aqueous solution of sodium perborate. Low-molecular-weight chitosan is dissolved in an aqueous solution of acetic acid, dichloroacetic acid, or formic acid alone or in a mixture to form an acidic chitosan solution, and the concentration is within an easy-to-handle range, that is, 2 to 2.
You can freely choose within a range of 20%. A fixed amount of the acidic solution is dropped into the next basic coagulation bath under pressure from, for example, a pore size of 0.1 to 0.25 m/m to obtain granular porous chitosan. As the basic substance in the coagulation bath, alkaline substances such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonia, and ethylenediamine are used.The basic solution is water, or polar substances such as methanol and ethanol. The basic substance is added to an alcohol or a mixture of water and alcohol. The granular porous chitosan forms a fine structure as the desolvation reaction progresses while settling in the coagulation liquid in granular form. The precipitated granular coagulum is taken out and washed with water until it becomes neutral to obtain granular porous chitosan. Next, the water used for washing is removed by displacement from the granular porous chitosan using a polar solvent. Crosslinking of chitosan spherical coagulates is carried out in a solution in which an organic diisocyanate compound is dissolved in a polar solvent that is the same as or different from the polar solvent used for water displacement. After sufficient crosslinking, unreacted After the organic diisocyanate compound is thoroughly washed away with the polar solvent used in the reaction, the mixture is further washed thoroughly with water to obtain crosslinked granular porous chitosan. The polar solvent used in the present invention includes alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, and amides such as dimethylformamide and dimethylacetamide. May be used. Examples of the organic diisocyanate include 4,4'-diphermethane diisocyanate, 2,4-tolylene diisocyanate, naphthalene diisocyanate, 1,4-diclohexane diisocyanate,
Examples include 4,4'-dicyclohexylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and the like. The amount of organic diisocyanate is 0.5 to 1 per mole of glucosamine residue in chitosan.
mol, and catalytic crosslinking is carried out under reaction conditions of 30 to 60°C for 0.5 to 4 hours. In addition, when an anion exchanger is produced by reacting with an organic halide as described below using porous granular chitosan that is not brought into contact with an organic diisocyanate,
The obtained anion exchanger is completely dissolved in 1N-NCl. Furthermore, when porous granular chitosan that is not brought into contact with an organic diisocyanate is partially chitinized with acetic anhydride, the anion exchanger particles are brittle and have a strength disadvantage. The granular porous chitosan crosslinked as described above is brought into contact with a 50% aqueous solution of caustic soda, caustic potash, etc. as a basic aqueous solution by immersion. The contact conditions may be 40°C for about 24 hours. With this process,
The OH group in the porous granular chitosan molecule is -ONa group,
Or converted to -OK group, etc. Further, an organic halide reagent having a substituted or unsubstituted amino group or a substituted quaternary ammonium group having anion exchange ability is applied in an amount necessary to develop the desired ion exchange ability. As the organic halide, β-diethylaminoethyl chloride hydrochloride, β-chloroethylamine hydrochloride, etc. are generally used. When reacting with an organic halide reagent, −ONa
Since it is undesirable if the group or -OK group is easily converted to -OH group, the chitosan porous granules treated with the basic aqueous solution are suctioned under reduced pressure to sufficiently remove the excess basic aqueous solution. Furthermore, it is necessary to react with an organic halide reagent in an organic polar solvent such as isopropyl alcohol. Thereafter, the product is further thoroughly washed with an organic polar solvent such as isopropyl alcohol, such as with water or hot water, deionized with a basic aqueous solution, and then thoroughly washed with deionized water to obtain a chitosan-based anion exchanger. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the scope described in the Examples. ΓTotal ion exchange capacity (CTW) per dry weight unit
The measurement method involves taking approximately 100 ml of a wet sample that has been washed with 1N NaOH and deionized water, adjusting the water balance, and quickly weighing approximately 30 g each to calculate the next operation. (1) Dry the exact weight W ₂ (g), dry weight W ₃
Find (g). (2) Take the exact weight W ₁ (g) and add N/5-HCl
Pour into 500 ml of water, stir occasionally and leave for 12 hours or more. Take 10ml of this solution and add N/10-NaOH
Perform neutralization titration using phenolphthalene as an indicator, and calculate the total ion exchange capacity (CTW) using the following formula. (meq/g) (3) CTW=(ba-a)×NaOH×1/10×500/10
×100/W ₁ × (100-moisture content) (meq/g) However: b: N/10-NaOH consumption of sample a: N/10-NaOH consumption of blank NaOH: N/10-NaOH consumption Titer water content = W ₂ - W ₃ / W ₃ × 100 (%) Γ Swelling degree is Swelling degree (%) = Y-X/X × 100 Y: Swell the sample in IN-HCl or 4N-NaOH After that, the sample was dehydrated under reduced pressure to adjust the water balance. X: Wet weight after the sample was dehydrated under reduced pressure to adjust the water balance. Example 1 60 g of chitosan with a degree of deacetylation of 80% and an average molecular weight of 43,000 was dissolved in 910 g of water containing 30 g of acetic acid,
A chitosan solution with a viscosity of 2700 cp was obtained. This is 0.25
After dropping into a basic solution consisting of 10% caustic soda, 30% methanol, and 60% water through a m/m hole diameter nozzle and allowing it to solidify and precipitate, it was thoroughly washed with water until it became neutral, and a diameter of 0.8 m/m was formed. Granular porous chitosan with a specific surface area of 78.6 m ² /g was obtained. After 50 ml of this was taken and suctioned under reduced pressure to remove the water contained therein, it was placed in 100 ml of acetone organic polar solvent to sufficiently replace the water with the polar solvent. Add this to 1 glucosamine residue in 100 ml of acetone.
Add 1 mol of 4,4'-diphenylmethane diisocyanate (MDI) per mole, react at 30°C for 30 minutes, and wash unreacted MDI thoroughly with acetone.
Further, granular porous chitosan was obtained by thoroughly washing with water and contacting with an organic diisocyanate. 47% caustic soda 200% in this granular porous chitosan
After injecting ml, stir the reaction at 40℃ for 24 hours, then vacuum the solution to remove the attached caustic soda aqueous solution, and inject 100ml of isopropyl alcohol.
For sample numbers 1 to 5, hydrochloric acid β-diethylaminoethyl chloride was used as the organic halide reagent,
For sample numbers 6 to 10, 0.5 g, 1 g, 2 g, 5 g, and 10 g of β-chloroethylamine hydrochloride were added to 100 ml of porous granular chitosan, respectively.
The reaction was carried out at ℃ for 4 hours. After that, an additional 100 ml of isopropyl alcohol was injected three times, followed by washing with water and hot water to obtain a chitosan-based anion exchanger. The specific area, CTW, degree of swelling in 1N-HCl and 4N-NaOH were measured, and the results shown in Table 1 were obtained.

[Table] Example 2 Chitosan porous granules obtained in the same manner as in Example 1 were mixed with 0.5 mol of hexamethylene diisocyanate (HDI) per 1 mol of glucosamine residue in 100 ml of dimethylformamide at 60°C. After reacting for a time, unreacted HDI was thoroughly washed in dimethylformamide, and then thoroughly washed with water to obtain granular porous chitosan. This chitosan was used in Example 1.
In the same manner as above, using β-chloroethylamine hydrochloride as the organic halide, 5 g, 2 g, and 1 g were added to obtain a chitosan anion exchanger. The specific surface area CTW, swelling degree of 1N-HCl and 4N-NaOH were measured, and the results shown in Table 2 were obtained.

[Table] Example 3 Using 60 g of chitosan with a degree of deacetylation of 80% and an average molecular weight of 47,000, the same operation as in Example 1 was performed to obtain porous chitosan with a specific surface area of 80.6 m ² /g and a particle size of 1.0 m/m. 1 mole of glucosamine residue in chitosan was reacted with 1 mole each of xylylene diisocyanate (XDI) or tolylene diisocyanate (TDI) at 30°C for 1 hour in the same manner as in Example 1. Then, 10 g and 5 g of 2 g of β-diethylaminoethyl chloride hydrochloride as an organic halide were reacted in isopropyl alcohol to obtain a chitosan-based anion exchanger. Table 3 shows the results of measuring the specific surface area and degree of swelling in CTW, 1N-HCl, and 4N-NaOH.

〔Effect of the invention〕

As described in the above examples, the chitosan-based anion exchanger obtained by the present invention has a total ion exchange capacity 8 to 6 times stronger than that of the conventional one, and moreover, The total ion exchange capacity can be freely controlled by selecting conditions. Furthermore, since it has excellent swelling resistance against acids and alkalis, it can be used in a wide range of ion exchange capacities. In addition, the chitosan-based anion exchanger obtained by the present invention has uniform micropores on the fractured surface and surface of the granules, and has high strength despite having a large specific surface area. Even when used by filling a column etc., there is no deformation and no increase in liquid flow resistance.

Claims (1)

[Claims] 1. Particulate porous chitosan obtained by dissolving low molecular weight chitosan in an acidic aqueous solution and dropping the solution into a basic solution is contacted and crosslinked with an organic diisocyanate compound in a polar solvent, and then brought into contact with a basic solution. A method for producing an anion exchanger, which comprises reacting the anion exchanger with an organic halide having a substituted or unsubstituted amino group or a substituted quaternary ammonium group.