JPS59227901A - Treatment of chitin - Google Patents

Abstract

PURPOSE:To obtain chitin having an improved solvent solubility and a high purity and providing a molding of excellent mechanical properties, by treating chitin with a nonaqueous solvent containing a specified acid. CONSTITUTION:1pt.wt. chitin from which part or most of impurities such as Ca compounds and proteins were removed and which has a particle diamater <=50 mesh is mixed with 5-20pts.wt. nonaqueous solvent (e.g., methyl alcohol) containing 0.5-20mol, per mole of chitin, of acetic, propionic, or butyric anhydrides, and the mixture is heated at 20-80 deg.C for 30min or longer, neutralized with an alkali, washed and dried.

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, and further relates to a method for producing chitin that can provide a molded article with high purity and improved mechanical properties. Production of chitin that has good solubility in Q and 2 solvents when it is made into 1--p, solidified with a coagulating liquid, and then wet-molded, and the resulting molded product has high strength. It is about the method.

Chitin is a substance widely distributed in nature, such as in crustaceans, which is composed of poly(N-acetyl-D-glycolymin), and has one aminoacetyl group in each repeating unit of its molecule. Therefore, it has many interesting and unique properties. One of these properties is that it undergoes enzymatic decomposition in vivo and is absorbed into tissues, and it has been considered that it could be used as a material for absorbable sutures and the like. Chitin, which is obtained by refining natural products used by Shime, Shi, Ashiki, et al., is completely dissolved when dissolved in a solvent (in good cases, there may be some in the /8 solution). The insoluble force (existing 7) of such a solution has excellent mechanical performance ■[
: There was a problem that it was difficult to obtain molded products such as films.

The inventors of the present invention have carried out extensive research in view of this fact, and have found that it is possible to treat chitin under specific conditions, thereby dissolving it in a solvent. The present invention was achieved based on the discovery that a molded product having improved properties and excellent strength and mechanical performance can be obtained.

Specifically, the present invention is a method for treating chitin, which is characterized in that chitin is treated with a non-aqueous mixture containing any one of acetic anhydride, pionic anhydride, and acetic anhydride.

Chitin in the present invention refers to chitin and its derivatives contained in the exoskeleton of crustaceans. Examples of chitin derivatives include etherified chitins such as carboxymethylated chitin and hydroxyedylated 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 a powder, particularly a powder thicker than 50 mesosinus, is preferably used. Here, purification refers to calcium compounds from natural products containing chitin.

It refers to the removal of substances other than chitin, such as proteins.
For example, Ricca'doa, 8, Muzzarelli, published by Pergamon Press.
4? ``chitin'' P, 90 (1977) (rMethod of llackman)
I can list the operations of J. That is, it refers to the removal of some or most of the impurities by methods such as removing calcium compounds by acid treatment such as hydrochloric acid, and removing proteins by alkaline treatment such as caustic soda.

In the present invention, such chitin is treated with a non-aqueous solvent containing any one of acetic anhydride, propionic anhydride, and butyric anhydride. Examples of the non-aqueous solvent preferably used in the present invention include 1, for example, methyl alcohol, Ethyl alcohol, propyl alcohol.

Alcohol cheeks such as butyl alcohol, acetone.

Organic solvents include ketones such as methyl ethyl ketone, amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

The amount of acetic anhydride, propionic anhydride or butyric anhydride used is preferably 0.5 to 20 mol per mol of chitin,
The amount of non-aqueous solvent used is preferably 5 parts by weight of chitin.
~20 parts by weight. The treatment temperature is preferably 20 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 white discoloration can be obtained as described above, but the treatment can be confirmed by 1. For example, if chitin powder is treated with a methanol solution containing 5% by weight of glutaraldehyde at 40°C for 6 hours, untreated This can be done because, in contrast to the yellowish-brown coloration, the treated material does not undergo coloring, or even if it does, 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 can be dissolved in dimethylacetamide or a mixed solvent of N-methylpyrrolidone and lithium chloride to form a dope. It can be molded into sea 1, etc. The use of chitin treated by the method of the present invention can have different characteristics from the use of conventional chitin, particularly in the following points. (1) It has excellent solubility in solvents and has a small amount of insoluble matter. (2) The degree of polymerization decreases little during dissolution, and a value close to the degree of polymerization before dissolution can be maintained. (3) A molded article with high mechanical performance, 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 Chione cepes opili
After thoroughly washing the skeleton of the o-o fabric with water, it was thoroughly dried in a warm air dryer at 40°C, and then crushed in an impact crusher (fine Micron Victory Mill VP-10).
It was powdered to 100 methane. 220 g of this powder was treated with 2N hydrochloric acid at room temperature for 5 hours, and 91 g of this powder was further treated with 500 ml of 2N hydrochloric acid. After the treated powder was washed with water, it was treated with 500 ml of IN-hydrocarbon soda at 100°C for 12 hours, then washed with water, and dried to give the purified chitin a blue color.

, 2 IOQg of chitin was added to a mixture 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.

This powder was mixed with methane containing 5% by weight of glutaraldehyde.
When the sample was immersed in a liquid solution at pH=7.4 and 45°C for 6 hours, no coloring occurred and the sample remained white. In contrast, the untreated powder was colored yellowish-brown.

On the other hand, 50 g of chitin powder after acetic anhydride treatment was mixed with 1000 g of N-methylpyrrolidone solution containing 8% by weight of lithium chloride.
g, and 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 a 2000 mesh stainless steel net, the filtration pressure of dope A was 3.
．． While it was 8 kg/cJ, the filtration pressure of Dope B was 6.7 kg/cJ. Put these dopes in a tank and pump it with a gear pump to a diameter of 0.08mmψ, 10
Discharge from the nozzle of 0 pole into isobutanol at 70°C 1 After coagulating in isobutanol for about 2 seconds, lO
The fibers were removed at a speed of 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 strength of 4.28 g/d, whereas the fibers obtained from Schiff and Dope B had a strength of 4.03 g/d.

Example 2. Comparative Example 2 Chione cepes opili
The exoskeleton of the o-o fabrecus) was sufficiently washed with water, thoroughly dried in a warm air dryer at 40°C, and then crushed in an impact crusher (fine micron Victory Mill VP-10) for 50 minutes.
Powdered to 0 me nosh. This powder was treated with 2N hydrochloric acid at room temperature for 5 hours, washed with water, and treated with IN-hydrocarbon soda at 85°C for 6 hours. Wash the obtained chitin powder with water.

Dry and purified chitin was obtained.

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 mixed with 1000 g of N-methylpyrrolidone/8 solution containing 8% by weight of lithium chloride. Add at 25°C.

Dope C was prepared by thorough stirring and mixing. For comparison, when we attempted to dissolve chitin in /8 under the same conditions using untreated powder, only 50 gL was not melted, but Dope D was obtained at that concentration. Put these dopes in the tank,
The liquid was fed by a gear pump and discharged from a 0.07 mmψ, 50-pole nozzle into isobutanol at 75°C, and after solidifying, it was withdrawn at a speed of 5 m7 and washed with methanol to obtain fibers. When the dry strength of the obtained fibers was measured, the fiber obtained from Dope C was 4.28 g/d, while the fiber obtained from Dope D was 3.96 g/d.
g/d.

Patent applicant: Unijinriki Co., Ltd.

Claims (1)

[Claims] (A method for treating chitin, which comprises treating 1,1 chitin with a non-aqueous solvent containing any one of acetic anhydride, propionic anhydride, and butyric anhydride.