JPH051282B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing chitin that can provide a molded article with high purity and improved mechanical properties. The present invention relates to a method for producing chitin that has good solubility in a solvent when coagulated and wet-molded, and can provide molded products with high strength.

Chitin is a substance widely distributed in nature, such as the exoskeleton of crustaceans, which is made of poly(N-acetyl-D-glycosamine), and has one aminoacetyl group in each repeating unit of its molecule, so it has many It has interesting and unique properties. One such property is that it undergoes enzymatic decomposition in vivo and is absorbed into tissues, and has been considered for use as a material for absorbable sutures and the like. However, when chitin, which is conventionally obtained by purifying natural products, is dissolved in a solvent, the dissolution is not complete, and some undissolved substances are present in the solution. There was a problem in that it was difficult to obtain molded products such as fibers and films with excellent mechanical performance.

The inventors of the present invention have conducted extensive research in light of the above circumstances, and have found that by treating chitin under specific conditions, its solubility in solvents is improved, and molded products with excellent mechanical performance can be produced from it. The present invention has been developed based on the discovery that this can be achieved.

That is, the present invention provides a treatment for chitin, which is characterized in that chitin is treated at 30° C. or higher for 30 minutes or more in an alcoholic solution containing 0.5 mol or more of any of acetic anhydride, propionic anhydride, or butyric anhydride based on chitin. The gist is the method.

Chitin in the present invention refers to chitin and derivatives thereof contained in the exoskeleton of crustaceans. Examples of chitin derivatives include etherified chitins such as carboxymethylated chitin and hydroxyethylated chitin, and esterified chitins such as acetylated chitin and sulfonated chitin.

In carrying out the method of the present invention, purified chitin from which some or most of the impurities have been removed is generally used, but powder, particularly powder finer than 50 mesh, is preferably used. Here, purification refers to the production of calcium compounds from natural products containing chitin,
Refers to the removal of substances other than chitin, such as proteins. For example, “chitin” by Riccadoa.A.MuzzareIIi, published by Pergamon Press, P.90
(1977).
I can show you how to use "Hackman". That is, it refers to the removal of some or most of the impurities by a method in which calcium compounds are removed by acid treatment such as hydrochloric acid, and proteins are removed by alkaline treatment such as caustic soda.

In the present invention, such chitin is treated with an alcohol solution containing any one of acetic anhydride, propionic anhydride, and butyric anhydride. Examples of alcohols preferably used in the present invention include methyl alcohol, ethyl alcohol, propyl alcohol, Examples include butyl alcohol.

The amount of acetic anhydride, propionic anhydride or butyric anhydride used is preferably 0.5 to 20 mol per mol of chitin, and the amount of alcohol solution used is preferably 5 to 20 parts by weight per 1 part of chitin. The treatment temperature is preferably 30 to 80°C and the treatment time is preferably 30 minutes or more. After the treatment, the chitin is transferred to a solution such as water, neutralized with an alkali, thoroughly washed, and then dried. Chitin with high whiteness can be obtained as described above, but to check the treatment, for example, if chitin powder is treated with a methanol solution containing 5% by weight of glutaraldehyde at 40°C for 6 hours, untreated chitin will turn yellow. This can be done because the treated material is not colored, or even if it is colored, the degree of coloration is lower than that of the untreated material.

Chitin treated by the method of the present invention can be used as it is, or can be dissolved in a solvent to form a dope and used as a molded article. For example, it is dissolved in dimethylacetamide or a mixed solvent of N-methylpyrrolidone and lithium chloride to form a dope, and coagulated with a coagulant such as methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, etc. to produce fibers,
It can be formed into films, sheets, etc.
Using chitin treated with the method of the present invention,
In particular, it can have the following characteristics different from the case of using conventional chitin. (1) Excellent solubility in solvents and low insoluble matter; (2) Small drop in degree of polymerization during dissolution; can maintain a value close to the degree of polymerization before dissolution; (3) Mechanical performance , molded products with particularly high strength can be obtained.

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

Example 1, Comparative Example 1 Red snow crab (chione cepes opilio-o
After thoroughly washing the skeleton of the material (Fabricus fabricus) with water, it was sufficiently dried in a hot air dryer at 40°C, and then powdered into 100 meshes in an impact type powder frame machine (Hosokawa Micron Victory Mill VP-10). 220g of this powder
- treated with hydrochloric acid at room temperature for 5 hours;
91 g was treated with 500 ml of 2N hydrochloric acid. After washing the treated powder with water, it was washed with 500ml of 1N caustic soda.
The mixture was treated at 100°C for 12 hours, then washed with water and dried to obtain purified chitin.

100 g of this chitin was added to a mixed solution of 250 g of acetic anhydride and 1000 g of methanol, and stirred at 57° C. for 4 hours. After 4 hours, the chitin was taken out and immediately neutralized, washed, and dried to obtain white chitin powder.

When this powder was immersed in a methanol solution containing 5% by weight of glutaraldehyde at pH=7.4 and 45° C. for 6 hours, there was no coloration and the powder remained white. In contrast, the untreated powder was yellow and colored.

On the other hand, 50 g of chitin powder treated with acetic anhydride was added to 1000 g of N-methylpyrrolidone solution containing 8% by weight of lithium chloride, and the mixture was sufficiently stirred and mixed to prepare Dope A. For comparison, Dope B was prepared using untreated powder under the same conditions. When these dopes were filtered through 2000 mesh stainless steel net, the filtration pressure of Dope A was 3.8 Kg/cm ² , while the filtration pressure of Dope B was 6.7 Kg/cm ² . These dopes are placed in a tank, pumped with a gear pump, and sprayed through a 0.08mmφ, 100-hole nozzle.
It was discharged into isobutanol at 70° C., coagulated for about 2 seconds in isobutanol, and then wound at a speed of 10 m/min to obtain fibers with a total denier of 58 d. When the dry strength of the resulting fibers was measured, the fibers obtained from Dope A had a dry strength of 4.28 g/d, while the fibers obtained from Dope B had a dry strength of 4.03 g/d.

Example 2, Comparative Example 2 Red snow crab (chione cepes opilio-o
After thoroughly washing the exoskeleton of the exoskeleton (Fabrecus) with water, it was thoroughly dried in a hot air dryer at 40°C, and then powdered into 50 meshes in an impact-type powder frame (Hosokawa Micron Victory Mill VP-10). This powder was treated with 2N hydrochloric acid at room temperature for 5 hours, washed with water, and treated with 1N caustic soda at 85°C for 6 hours. The obtained chitin powder was washed with water and dried to obtain purified chitin.

100 g of this chitin was added to a mixed solution of 300 g of propionic anhydride and 1000 g of ethanol, and the mixture was stirred at 60° C. for 5 hours. After 5 hours, the chitin was taken out and immediately neutralized, washed, and dried to obtain white chitin powder.

60 g of this powder was added to 1000 g of N-methylpyrrolidone solution containing 8% by weight of lithium chloride at 25°C.
Dope C was prepared by thorough stirring and mixing. For comparison, when an attempt was made to dissolve chitin under the same conditions using untreated powder, only 50 g was dissolved, but Dope D was obtained at that concentration. Put these dopes in a tank, pump them with a gear pump,
It was discharged into isobutanol at 75° C. through a 0.07 mmφ, 50-hole nozzle, solidified, and then taken out at a speed of 5 m/min and washed with methanol to obtain fibers. When the dry strength of the obtained fiber was measured, it was found that Dope C
The fiber obtained from Dope D was 4.28 g/d, while the fiber obtained from Dope D was 3.96 g/d.

Example 3, Comparative Examples 3 and 4 100g of chitin purified in Example 1 was mixed with 300g of acetic anhydride.
g and 1000 g of ethanol, and the mixture was stirred at 62°C for 3 hours. After 3 hours, the chitin was taken out and immediately neutralized, washed, and dried to obtain white chitin powder (Example 3).

On the other hand, 100 g of the same chitin was added to a mixed solution consisting of 300 g of acetic anhydride, 500 g of dimethylformamide, and 300 g of pyridine, and the mixture was reacted at 45° C. for 40 hours. After the reaction, remove the excess and wash the chitin thoroughly with water.
Drying was performed (Comparative Example 3).

Furthermore, 20g of the same chitin was added to 350g of trichloroacetic acid.
The mixture was added to a mixed solvent consisting of 650 g of 1,2-dichloroethane, and the mixture was maintained at 15° C. and mixed and dissolved while stirring. Furthermore, 108 parts of acetic anhydride was added,
Stirring was continued for 30 minutes, resulting in a homogeneous solution. This solution was allowed to stand at 4° C. for 20 hours, then coagulated with acetone, washed with water, the solvent was removed, dried, and pulverized (Comparative Example 4).

The chitin obtained in Example 3 and Comparative Examples 3 and 4 was added to a methanol solution containing 5% by weight of glutaraldehyde.
When immersed for 6 hours at PH7.4 and 45°C, Example 3
The samples of Comparative Examples 3 and 4 were colored yellowish brown, whereas the samples of Comparative Examples 3 and 4 were not colored at all.

On the other hand, each of these was 8% by weight of lithium chloride.
When dissolved in an N-methylpyrrolidone solution containing the following, a clear solution was obtained for Example 3, whereas in Comparative Examples 3 and 4, undissolved residue remained and the solution was opaque and had poor solubility. It turned out to be insufficient.

Claims (1)

[Claims] 1. A method for treating chitin, which comprises treating chitin at 30° C. or higher for 30 minutes or more in an alcoholic solution containing 0.5 mole or more of any of acetic anhydride, propionic anhydride, or butyric anhydride based on chitin.