JPH032891B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing chitin molded articles such as chitin fibers and films.

Chitin is a polysaccharide consisting of poly(N-acetyl-D-glucosamine), a substance widely distributed in nature such as the exoskeleton of crustaceans, and each repeating unit of its molecule contains one aminoacetyl group. It has many interesting and unique properties. One of them is that it is enzymatically degraded in vivo and absorbed into tissues, and that it has good stainability.For this reason, it is possible to make chitin into fibers and use it as absorbable surgical suture thread. A dike is being proposed.

The general method for molding chitin is to wet mold a dope made by dissolving chitin in a solvent.
Known examples of this solvent include, for example, a mixture of dimethylacetamide or N-methylpyrrolidone and lithium chloride, trichloroacetic acid, and the like. Among these, the mixture of dimethylacetamide or N-methylpyrrolidone and lithium chloride proposed in JP-A No. 52-100499 is an extremely good solvent for chitin because it causes little decomposition of chitin.

Various methods are known for purifying chitin, such as “chitin” by Riccadoa A. Muzzarelli published by Pergamon Press.
“Method of
Hackman'' is a typical example. However, chitin prepared in this manner has a high viscosity when used as a molding dope, and is generally unsuitable for wet molding. For example, the solution viscosity of chitin prepared by the above method is 800 centipoise or more when measured at 30°C using a solution of 2 g of lithium chloride dissolved in 25 g of dimethylacetamide at a concentration of 0.2 g/100 g dimethylacetamide. . The viscosity of this solution varies depending on the type of crustacean used as a raw material and the purification conditions, but unless harsh conditions are used, it will not fall below the above-mentioned 800 centipoise. When molding dope is prepared using such chitin, even if
Even if the solvent described in Japanese Patent No. 52-100499 is used, the viscosity of the dope becomes high, and as described in the same publication, the dope becomes extremely viscous, especially at a high concentration of 5% or more. Therefore, in general, when obtaining molded articles such as fibers and films, dopes with a chitin concentration of 2% by weight or more are not suitable for obtaining high-quality molded articles.

As a result of extensive research aimed at providing a method for manufacturing high-quality chitin molded articles with high productivity, the present inventors discovered that the above purpose could be achieved by using a specific chitin. ,
This has led to the present invention.

That is, in the present invention, when producing a chitin molded product by wet molding a chitin dope consisting of chitin, dimethylacetamide or N-methylpyrrolidone, and lithium chloride, 2 g of lithium chloride is mixed with 25 g of lithium chloride.
Using a solution dissolved in dimethylacetamide as a solvent, the concentration of 0.2g/100g dimethylacetamide solution,
This is a method for producing a chitin molded article, characterized by using chitin having a solution viscosity of 50 to 600 centipoise measured at 30°C.

The chitin used in the present invention includes not only chitin itself obtained by purifying natural products but also chitin derivatives. Examples of chitin derivatives used in the present invention include etherified chitins such as carboxymethylated chitin and hydroxyethylated chitin, and esterified chitins such as acetylated chitin and sulfonated chitin. Examples of esterified products include formic acid, acetic acid, butyric acid, valeric acid,
Carboxylic acids such as isobutyric acid, isovaleric acid, benzoic acid, cinnamic acid, salicylic acid, anthranilic acid, and phthalic acid, sulfonic acids such as sulfuric acid, toluenesulfonic acid, and sulfanilic acid, carbonates, or esterified products of their anhydrides. can give. The chitin used in the present invention is obtained by using a solution of 2 g of lithium chloride dissolved in 25 g of dimethylacetamide as a solvent.
Concentration 0.2g/100g dimethylacetamide solution, 30℃
The viscosity of the solution measured at is from 50 to 600 centipoise, preferably from 80 to 400 centipoise, and more preferably from 100 to 300 centipoise. Solution viscosity is measured with a B-type viscometer. The chitin used in the present invention can be obtained by the general method of drying and pulverizing the exoskeleton of a crustacean, treating it with an acid such as hydrochloric acid, and then treating it with an alkali such as caustic soda to sufficiently decalcify and deproteinize it. It can be prepared by performing purification treatment and then further treatment with acid such as hydrochloric acid. The solution viscosity can be adjusted by adjusting the type of acid used, concentration, temperature, bath ratio, and time. For example, chitin purified by the above-mentioned "Method of Hackman" has a solution viscosity of 800 centipoise or more.
In order to obtain chitin having the solution viscosity referred to in the present invention, such chitin may be treated with hydrochloric acid as follows, for example. That is, chitin with a solution viscosity of 1000 centipoise was prepared using 1/2N hydrochloric acid at 60%
Approximately 100 centipoise chitin can be obtained by treating at 30°C for 30 minutes, and 250 centipoise chitin can be obtained by treating with 1N hydrochloric acid at 30°C for 2 hours. By changing the treatment conditions in the same manner, various chitins used in the present invention can be prepared. Moreover, the chitin used in the present invention can also be directly prepared by employing strict conditions when acid-treating the shell raw material. However, in order to obtain a high-quality chitin molded article, it is preferable to first obtain purified chitin using a conventional method and then perform acid treatment.

In the present invention, a mixture of dimethylacetamide or N-methylpyrrolidone and lithium chloride is used as the solvent for forming the dope. The blending ratio of lithium chloride to dimethylacetamide or N-methylpyrrolidone is preferably 2wt.
% or more.

The dope used in the present invention can be prepared by a known method, and the melting temperature is not particularly limited.
It can be carried out at 20-30°C. The chitin concentration in the dope is preferably 2 to 10 wt%. In the method of the present invention, a relatively high concentration of dope can be used as described above, so chitin molded articles can be obtained with high productivity.

Various known methods and devices can be used for wet molding of chitin dope. For example, by extruding dope through a nozzle with a fine hole,
Chitin fibers can be obtained by wet spinning in which the fibers are coagulated in a coagulating liquid such as isobutanol and then taken up with rollers. In addition, molded products such as ribbons, films, and sheets can be obtained by known wet molding methods.

According to the present invention, a chitin molded article can be obtained with good moldability, for example, with less yarn breakage during spinning. Furthermore, molded products of excellent quality, such as high strength, can be obtained with good productivity.

On the other hand, when chitin with a solution viscosity of less than 50 centipoise is used, only molded products of inferior quality can be obtained, while when chitin with a solution viscosity of more than 600 centipoise is used, there are many troubles during molding, and the molded products cannot be obtained. The quality of the molded product also tends to be inferior. In addition, when a solvent other than that used in the present invention is used as a solvent, the effects of the present invention are not sufficiently exhibited, probably because chitin decomposes over time from the time of preparing the dope to the time of molding. I can't do it.

The present invention will be explained in more detail below by giving examples.

Example 1 Red snow crab (Chione Cepes Opilio)
After thoroughly washing the exoskeleton of O′fabricus),
Thoroughly dry in a hot air dryer, and then grind to 100% in an impact crusher (Hosokawa Micron Victory Mill VP-10).
Powdered into mesh. 220g of the powder
Treated with 2N-hydrochloric acid at room temperature for 5 hours, and then
91 g was treated with 500 ml of 2N hydrochloric acid for 2 days. After washing these with water, 12 hours with 500ml of 1N caustic soda at 100℃.
After being treated for a period of time, it was washed with water and dried. The viscosity of the solution of chitin thus obtained was measured using a B-type viscometer at 30°C using a solution of 2 g of lithium chloride dissolved in 25 g of dimethylacetamide at a concentration of 0.2 g/100 g of dimethylacetamide. It turned out to be 985 centipoise. When this chitin was further treated with 1N hydrochloric acid at 40°C for 1 hour, the solution viscosity decreased to 305 centipoise.

This chitin was dissolved at room temperature in dimethylacetamide:lithium chloride=20:1 to a concentration of 3 wt%, and filtered and defoamed to obtain a transparent and viscous dope. This dope was placed in a tank, fed with a gear pump, discharged through a 0.08 mmφ, 50-hole nozzle, coagulated in isoptanol, and then wound at a speed of 10 m/min to obtain a 61 denier fiber. The texture was extremely good. The dry strength of this chitin fiber after washing with water and drying was 3.81 g/d.

Comparative Example 1 A dope was prepared in the same manner as in Example 1, except that the chitin having a solution viscosity of 985 centipoise prepared in Example 1 was used as it was without acid treatment, and then the same method as in Example 1 was used. When spinning using this method, yarn breakage occurred, so spinning could only be done at a speed of 3 m/min. Further, the yarn wound at this speed had a denier of 62 and a dry strength of 3.22 g/d.

Comparative Example 2 Chitin having a solution viscosity of 958 centipoise prepared in Example 1 was further treated with 1N hydrochloric acid.
After treatment at 60°C for 1 hour, chitin having a solution viscosity of 24 centipoise was obtained. A dope was prepared in the same manner as in Example 1 except that this chitin was used, and then fiberization was performed under the same conditions as in Example 1. The chitin fibers obtained had a denier of 63 and a dry strength of 2.62. It was g/d.

Claims (1)

[Claims] 1. When manufacturing a chitin molded product by wet molding a chitin dope consisting of chitin, dimethylacetamide or N-methylpyrrolidone, and lithium chloride, a solution of 2 g of lithium chloride dissolved in 25 g of dimethylacetamide as chitin is used as a solvent,
Concentration 0.2g/100g dimethylacetamide solution, 30℃
A method for producing a chitin molded article, characterized by using chitin having a solution viscosity of 50 to 600 centipoise as measured by .