JPS6125741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel chitin dope. Chitin is a polycontaining compound composed of poly-N acetyl D-glucosamine that is polycondensed with β (1→4) bonds and is widely distributed in nature and is found in shrimp, crabs, and other shellfish, grasshoppers, rhinoceros beetles, and other insects. It is a sugar. Because chitin has a chemical structure similar to cellulose, attempts have been made for a long time to use it in fibers and thin films, which are the main uses of cellulose.In particular, recently it has been used in semipermeable membranes and food packaging as an alternative to biological membranes. Application to thin films for industrial use is being considered. However, unlike cellulose, chitin has a crystal structure due to extremely strong intermolecular forces with aminoacetyl groups in its molecules, and it is hardly soluble in inorganic or organic solvents, but can be dissolved in formic anhydride with decomposition. It is only reported.

Under these circumstances, the present inventors previously considered increasing the solubility of chitin by converting it into viscose. That is, the method involves immersing chitin in a concentrated aqueous sodium hydroxide solution, freezing the resulting alkali chitin at a low temperature, xanthogenizing it with carbon disulfide, dissolving it in an aqueous sodium hydroxide solution, and repeating the freezing process.

As a result of various studies on improving the solubility of chitin and acetyl chitin, the present inventors found that an extremely uniform solution could be obtained if a polar solvent containing methanesulfonic acid or a specific metal halide salt was used as the solvent. This has led to the present invention.

That is, the gist of the present invention is that chitin or acetyl chitin, methanesulfonic acid and the general formula MX
(M represents Ca or Mg, X represents Br or Cl) A chitin or acetyl chitin dope characterized in that it consists of at least one solvent selected from polar solvents containing the compound.

The methanesulfonic acid of the present invention and the polar solvent containing the compound of the general formula MX may be used alone or in combination. It is also possible to use other organic solvents such as formic acid.
Polar solvents containing MX compounds include hexamethylphosphoramide, N-methylpyrrolidone 2, dimethylacetamide, dimethylformamide, tetramethylurea, and dimethyl containing about 0.5 to 0.4 wt% of magnesium chloride or bromide or calcium chloride or bromide. Sulfoxide, tetramethylene sulfoxide, dimethylethylene urea, tetramethylmalonamide, N-methylcaprolactam, N
Preferred examples include acetylpyrrolidine, diethylacetamide, N-ethylpyrrolidone, and dimethylpropionamide. Among these solvents, methanesulfonic acid is the most preferred because it is easy to handle and causes almost no decrease in the molecular weight of chitin when treated at low temperatures. The amount of chitin or acetyl chitin added and dissolved in the solvent is preferably 20% or less by weight. When the amount added is large, there is a tendency for slight suspension. Although the lower limit is not particularly limited, a solution that is too diluted is not preferred because it will take time and effort to remove the solvent in the next step.
Preferably it is 0.5% or more, more preferably 1% or more.

The dope of the present invention is achieved by a method of gradually adding and dissolving chitin or acetyl chitin while maintaining the solvent at a temperature above the melting point of the solvent and stirring. The dope can also be produced satisfactorily by a freezing method in which the material is frozen and then dissolved in a solvent at room temperature.

The dope thus obtained is shaped into a desired shape. The dope is preferably heated above the melting point of the solvent.
It is extruded through a nozzle and T-die at a temperature of 10°C or higher and is regenerated while removing the solvent in a coagulation bath. Next, the material is shaped by winding it up or not winding it up and then passing through a washing, stretching, drying, or hot stretching process. Note that washing and stretching may be performed at the same time or in the reverse order. When shaping fibers, the coagulation bath is, for example, isopropyl ether, and when a second coagulation bath is provided, a mixture of ethanol, acetic acid, and water is appropriately used. The stretching step is preferably carried out in water, and the stretching ratio is preferably 1.05 times or more and 3 times or less, preferably about 1.1 to 1.5 times.

These preferred process diagrams are shown in FIG. 1, in which the dope 1 is extruded from the nozzle 3 by pressure 2, the spun yarn passes through the first coagulation bath 4 and the second coagulation bath 5, and then the washing bath 5. The film passes through the washing bath 8, where it is washed and at the same time is stretched between the first roller 6 and the second roller 7, and then wound into the winder 9.

The present invention will be specifically explained below using Examples.
Chitin was obtained by treating red king crab with dilute hydrochloric acid and then treating it with hot dilute alkali to separate the protein.It has the chemical formula C ₈ H ₁₁ NO ₃ (OH) ₂ .1/2H ₂ O (analytical value C: 44.96%).
A powder represented by H: 6.50% N: 6.57% was used. The acetyl chitin used was mono- or diacetylated chitin treated with acetic anhydride in the presence of hydrochloric acid, methanesulfonic acid or perchloric acid. Parts represent parts by weight.

Example 1 6 parts of acetic anhydride and 4 parts of methanesulfonic acid were mixed at 0°C, and 1 part of chitin was added with stirring. Approximately 5
It became viscous over time. After standing overnight at 0°C, ice water was added to the mixture to cause precipitation. The resulting precipitate was separated, washed with water, neutralized with distilled water and aqueous ammonia, and boiled for 1 hour. The precipitate was separated and dried. When 5 parts of diacetyl chitin (chemical formula [C ₈ H ₁₁ NO ₃ (OCOCH ₃ ) ₂ ] obtained in this way was dissolved in 95 parts of formic acid containing 8 parts of methanesulfonic acid at 30°C, a homogeneous and transparent dope solution was obtained. This dope was
It was extruded from the die into isopropyl ether at 50°C and stretched 1.4 times between extrusion rollers. Then, when washed in boiling water at 90°C, a transparent 50μ thin film was obtained.

Example 2 Diacetyl chitin similar to that used in Example 1
When 10 parts were dissolved in 90 parts of a dimethylformamide solution containing 5 parts of calcium chloride at 80°C, a uniform and transparent dope solution was obtained. This dope at 30℃
The mixture was cast onto a glass plate and heated to evaporate most of the solvent, washed with water, and then dried. The obtained thin film was transparent and had a thickness of 80μ.

[Brief explanation of the drawing]

FIG. 1 shows a process diagram suitable for carrying out the present invention.

Claims (1)

[Claims] 1 Chitin or acetyl chitin and methanesulfonic acid and general formula MX (M is Ca or Mg, X is Br or
A chitin or acetyl chitin dope characterized by comprising at least one solvent selected from polar solvents containing a compound (representing Cl).