JPS58134101A - Dissolving method for chitin - Google Patents

Abstract

PURPOSE:Chitin is pretreated with a solution consisting of dimethylacetamide or N-methylpyrrolidone and lithium chloride, then dissolved at higher temperature and filtered to give a uniform chitin dope with good filtering characteristics. CONSTITUTION:Chitin is pretreated with a solution containing more than 2wt% lithium chloride in dimethylacetamide or N-methylpyrrolidone at 0-16 deg.C, then dissolved at a temperature higher than 16 deg.C, preferably at 17-40 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dissolving chitin to prepare a uniform dope with good filterability.

The real thing is df! It is a polysaccharide consisting of (1-acetyp-D-gu*: ltmine), and is a substance widely distributed in silver, such as the exoskeleton of shellfish IIm.
Because it has one acetylamino group per return unit, it has interesting transient properties.

One of the advantages is that chitin can be broken down by enzymatic decomposition and absorbed into tissues in the living body, and has good easterly properties.For this reason, chitin can be made into fibers and used as an absorbable surgical suture thread. It is widely used.

The general method for molding chitin is wet molding in which chitin is soaked in a solvent. However, when dissolving chitin in this solvent to prepare a dope, a wet process is preferably used to obtain a dope with a chitin concentration of 2% or more, which is generally If chitin is dissolved at a temperature higher than room temperature, the dissolution of chitin will suddenly change and the dope will become extremely viscous. There were problems in that the dope had a large amount of dissolved gel and had poor filterability, and the molded products obtained therefrom did not have sufficient performance such as strength.

The present inventors have conducted intensive research to develop a method for preparing a dope with a high concentration of 1st chitin (even in a solubility state of 1). The present invention was achieved based on the discovery that a chitin dope with excellent filterability can be obtained by keeping the material for a long time.

That is, the present invention provides dimethylacetamide or N-methylpyrrolidone and 9. This method of dissolving chitin is characterized in that when dissolving chitin in a solution consisting of chloride and thium, the chitin is previously treated with the solution at a temperature of 16°C to 16°C and then dissolved at a temperature higher than 16°C.

The chitin used in the present invention includes poly(N-acetyl--
In addition to the D-G~Kosamine) itself, there is also Kichi.

This also includes rust conductors. Such chitin is found in 9 e.g. crustaceans,
It can be prepared by treating the exoskeleton of insects, etc. with hydrochloric acid and hydrochloric acid to separate and purify the exoskeleton and protein, or by etherifying, esterifying, etc. Examples of chitin conductors preferably used in the present invention include spruped chitin such as carboxymethylated chitin and sulfonated chitin. Examples of esterified products include formic acid, acetic acid, butyric acid, valeric acid, and isobutyric acid. , benzoic acid, cinnamic acid, salicylic acid, anthrani acid, phthalic acid, etc.
Examples include esters of bonic acids, sulfuric acid, toluene sulphates, and anhydrides thereof.

The chitin used in the present invention includes 2 g of lithium chloride.
Using a solution of 259 V methylacetamide C as a solvent, the concentration is 0.29/100? The dimethylacetamide solution has a solution viscosity (hereinafter abbreviated as "solution viscosity") measured at 30C, preferably 50 ape or more, I! preferably 50 to 600 cpa, iIC preferably 80 to 400.
cpa, preferably 10.0 to 500 cps. Solution viscosity is measured with a BW1 viscometer. For example, after drying and pulverizing the exoskeleton of a mesospore, it is treated with an acid, followed by an alkali treatment with a caustic acid, etc., to obtain a sufficient amount of decomposition, force μVum, -
After performing the general purification process of protein
! It can be prepared by performing acid treatment such as c-filling acid.

In the present invention, dimethylatoamide or N-methylpyrrolidone is used as a solvent for chitin, and salts 1 and 4 are used. ,,． 6.9 ka 8□I, wa, ka 89. The ratio of lithium chloride to dithylacetamide or N-methylpyrrolidone is preferably 2% by weight or more. When the amount of lithium chloride is small, the solubility in chitin tends to decrease.

To dissolve chitin by the method of the present invention, it is first treated with a solution of dimethylacetamide or N-methylpyrrolidone and lithium chloride at a temperature of 0 to 16°C. It is necessary. Such processing is 1 e.g. υ~16C
This can be carried out by adding chitin powder to the above-mentioned solution heated to a simmering temperature and stirring if necessary. A known dissolving device can be used as the processing device. Processing temperature is 0
If the temperature is below .degree. C., lithium chloride may precipitate or a long treatment time will be required to bring out the effects of the present invention, which is not economical. On the other hand, when the temperature exceeds 16°C, the viscosity of the solution increases rapidly, so only a dope containing undissolved gel can be obtained.
Only moldings with poor performance can be obtained from such dopes. Processing time.

Although it varies depending on the type of solvent, processing temperature, stirring conditions, etc., 60 minutes to 2 hours is generally sufficient.

In the present invention, the above-treated chitin is dissolved in a solution consisting of dimethylacetamide or N-methylpyrrolidone and -lithium chloride at a temperature higher than 16°C. The above treatment i and dissolution may be performed in separate devices, but
It is convenient to carry out dissolution by raising the temperature after the above treatment in the same apparatus. The dissolution is carried out at a temperature higher than 16 DEG C., preferably between 17 DEG and 40 DEG C., for 1 to 2 hours, with stirring.

For example, chitin powder is added to a dimethylacetamide solution containing 8% lithium chloride, stirred at 6C for 60 minutes, heated to 17C, and stirred at 17-20C for 60-45 minutes, or added to a dimethylacetamide solution containing 8% lithium chloride. N- containing lithium
By adding to the methylpyrrolidone solution, stirring at 5°C for 30 minutes, raising the temperature to 20°C, and stirring at 20 to 50°C for 1 hour, a viscous dope with good transparency can be obtained.

According to the method of the present invention, it has a chitin concentration of 2 to 1% by weight, which is suitable for molding, and even 1840 mesh stainless steel net can be easily detected by filtration at a pressure of 1 to 2 #/d, and can be wet molded. This makes it possible to prepare a chitin dope that can produce molded products with good properties such as strength. Chitin fibers made from such chitin dope are flexible and easy to handle, preferably have a tensile strength of 5 #/d or more in the dry state, and are made into nine braids. By twisting the yarn, it is possible to obtain an absorbable surgical suture end that has sufficient strength, is easy to handle, and has excellent biocompatibility.

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 Chitin powder (manufactured by Kyowa Yushi ■) was treated with 1N citric acid at room temperature for 60 minutes, and then treated with 1N sodium hydroxide at 80°C for 60 minutes.
Purified chitin was obtained by time treatment. This purified chitin has an ash content of less than 0.1% by weight, and a solution viscosity of 60%.
It was 0 cps. This purified chitin 509 was mixed with dimethylacetamide 90% by weight and 10% by weight of lithium chloride.
In addition to 970 g of solvent adjusted to 3'c,
After stirring for 0 minutes, chitin swelled. Temperature 25℃
A transparent chitin dope was obtained within 60 minutes. When the obtained chitin dope was filtered using a 1480 mm stainless steel net, it could be easily filtered at a pressure of 1.5 #/d. The 101F of the filtered dope was taken, coagulated in acetone, and the weight after drying was measured, and it was 0.2959, and the chitin content in the dope was 2.
．． It was 95% by weight.

Comparative Example 1 Purified chitin S09 obtained in the same manner as in Example 1 was
When the same solvent 9709Cfi as in Example 1, which had been adjusted to 5°C, was stirred, the viscosity increased rapidly. Stirring was carried out for 30 minutes to obtain chitin dope. The obtained chitindog contained many fine gels and had low transparency. □ Filtration was attempted for this dope in the same manner as in Example 1, but 1.5#
Filtration was not possible at a pressure of /d, and a small amount of dope was obtained only at a filtration pressure of 6.5 #/d. Dope for filtration 109
The dope was taken, coagulated in acetone, and the weight after drying was measured and found to be 0.18609, and the chitin content in the dope was 1.86 weight. Further, when the dissolution time was increased to 2 hours, a filtration pressure of 7.2 to 9/d was required.

The filtered dope 109 was taken, coagulated in acetone, and the weight after drying was measured and found to be 0.249, and the chitin content in the dope was 2.4 weights t96.

Example 2 Ash content is 0.1% by weight or less and solution viscosity is 3500p
The purified chitin 509 of No. 8 was composed of 90% by weight of dimethylacetamide and 7% by weight of lithium chloride.
The mixture was added to 950 g of the prepared solvent, and after stirring for 1 hour, the temperature was raised to 25 C#c and stirring was continued for 45 minutes to obtain a chitin dope. The resulting chitin dope (7") had a high lightness (when filtered through a 1480 mesh stainless steel net, it could be easily filtered at a pressure of 2.0 phantom/d. The filtered dope 109 was coagulated in acetone. When the weight after drying was measured, it was 0.499, and the chitin content in the dope was 4.9% by weight.

Comparative Example 2 50f of the same purified chitin as in Example 2 was added to 950 g of the same solvent as in Example 2 adjusted to 25 cc and stirred for 45 minutes to obtain a chitin dope. The obtained chitin dope was opaque and was filtered through a 1.480mm stainless steel net, but a filtration pressure of 8.54/d was required. The chitin content in the filtered dope was 6.6% by weight.

Example 6 Purified chitin 609 having a solution viscosity of 150 cpa was added to 940 g of a solvent containing 94% by weight of N-methylpyrrolidone and 6.0% by weight of lithium chloride and adjusted to 1°C.
After stirring for an hour, the temperature was raised by 500°C and stirring was continued for 1 hour to obtain a chitin dope.

The obtained chitindog had high transparency (2.0 # when filtered using a stainless steel net of 1480 mm).
It could be easily filtered with a filtration pressure of /d. The chitin content in the rsa dope was 5.9% by weight.

Using a wet spinning device, this dope was pumped with a gear pump through a nozzle with a hole diameter of tJ, 0711N and 40 holes at a discharge rate of 1.1
Spun into globil alcohol (coagulation liquid) at 1 n/min,
It was picked up at a speed of 10111/min and sold to Twin Goo. Wash the wound yarn with methanol and water,
Chitin fibers were obtained by drying. The total denier of the obtained chitin fibers was 60d.

The tensile strength was 5.759/(1), the elongation was 1296, and it could be used as a suture yarn.

Patent applicant: Unitika Co., Ltd.

Claims (1)

[Claims] (1) When dissolving chitin in a solution consisting of dimethylace)amide or N-methylpyrodone and 9tium monide, it is also possible to treat chitin in advance at 0 to 16°C at a temperature higher than 16C. A method for dissolving chitin, which is characterized by being dissolved by temperature.