JPH0224304B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dope containing chitin.

Chitin is a polysaccharide that is widely distributed in nature, such as in the exoskeletons of crustaceans and the cell walls of molds, and has many interesting and unique properties because each repeating unit of its molecule contains one aminoacetyl group. are doing.
One of these properties is that it causes oxygen decomposition in the living body and is absorbed into the tissues. Taking advantage of this property, it has been proposed to make chitin into fibers and use it as absorbable sutures, films, non-woven fabrics, etc.

Chitin is a substance that is difficult to dissolve in general solvents, but conventionally preferred solvents include trichloroacetic acid, dichloroacetic acid (Japanese Patent Application Laid-open No. 133367/1982), dimethylacetamide or N-methyl containing a small amount of lithium chloride, about 5% by weight. Pyrrolidone solution (Japanese Patent Application Laid-Open No. 1983-
100499) has been proposed. Although these solvents appear to dissolve chitin well, they each have the following drawbacks. In other words, the former drastically reduces the degree of polymerization of chitin during dissolution;
The latter can only dissolve chitin with a relatively low degree of polymerization, and chitin with a high degree of polymerization cannot be completely dissolved. Therefore, chitin molded products such as fibers and films obtained from dopes made using these solvents do not have high mechanical properties, especially high strength, and cannot be used for applications that require high strength. For example, the reality is that it is difficult to use it for manufacturing absorbable sutures. For example, when manufacturing fibers from a dope made of trichloroacetic acid or dichloroacetic acid, or a dope made of N-methylpyrrolidone or dimethylacetamide containing a small amount of lithium chloride of about 5% by weight,
Unless a special method such as relaxing treatment in a coagulating solution immediately after spinning was used, only a product with a strength of up to about 3 g/d could be obtained.

As a result of the present inventor's earnest efforts to provide a chitin dope capable of obtaining high-strength fibers of, for example, 4 g/d or more without using a special spinning method, the inventors discovered that a large amount of lithium chloride and N-methyl It was discovered that pyrrolidone or dimethylacetamide and chitin form a good chitin dope, and that the molded products obtained from the dope are of good quality.
This has led to the present invention.

That is, the present invention provides a chitin dope consisting of (A) chitin, (B) lithium chloride, and (C) N-methylpyrrolidone or dimethylacetamide, in which lithium chloride exceeds the saturated dissolution amount of N-methylpyrrolidone or dimethylacetamide. It is a chitin dope characterized by containing a large amount of chitin.

It is surprising that a molded article with high mechanical strength can be obtained from a dope containing such a large amount of lithium chloride.

In the present invention, chitin includes not only chitin itself but also chitin derivatives. It can be prepared by treating the exoskeleton of such chitinous crustaceans, insects, etc. with acid and caustic soda to separate and purify the flea white matter and calcium content. Examples of chitin derivatives 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 carboxylic acids such as formic acid, acetic acid, butyric acid, valeric acid, isobutyric acid, isovaleric acid, cinnamic acid, salicylic acid, anthranilic acid, and phthalic acid, and sulfonic acids such as sulfuric acid, toluenesulfonic acid, and sulfanilic acid. , carbonates, or esterified products of their anhydrides.

The saturated dissolution amount as used in the present invention means the saturated dissolution amount of lithium chloride in N-methylpyrrolidone or dimethylacetamide, and its value depends on the type of solvent and temperature and shows different values. To determine the amount of saturated dissolution at a certain temperature, add a pre-weighed excess amount of lithium chloride to N-methylpyrrolidone or dimethylacetamide, and stir at a temperature approximately 20°C higher than the temperature to be measured until no further dissolution occurs. It can be determined by cooling to the temperature to be measured and weighing the lithium chloride present in solid form. The value of this saturated dissolution amount depends on the temperature, but in the range of 20 to 60°C, it is about 9 to 10% by weight (total weight of N-methylpyrrolidone or dimethylacetamide and lithium chloride; the same applies hereinafter).

In the present invention, the phrase "containing lithium chloride in an amount exceeding the saturated dissolution amount" means that lithium chloride is contained in N-methylpyrrolidone or dimethylacetamide in excess of the saturated dissolution amount. In view of the filterability of the dope, the amount of excess lithium chloride may range from a very small amount exceeding the saturated dissolution amount to about 2% by weight, especially about 0.7% by weight, and especially
A range of up to 0.5% by weight is preferred.

To prepare the dope of the present invention, for example, the following method can be adopted. First, lithium chloride is dissolved in N-methylpyrrolidone or dimethylacetamide to a saturated amount, and chitin is added to the solution and stirred to prepare a chitin dope. Next, lithium chloride in an amount exceeding the saturated dissolution amount is added to this dope, and the dope is stirred again to dissolve the dope. In this case, if the added lithium chloride is small, it will be dissolved in the dope and a uniform chitin dope will be produced again, and no lithium chloride will remain in the filter medium even after filtration.

The concentration of chitin in the chitin dope of the present invention is suitably in the range of 0.5 to 10% by weight based on the amount of N-methylpyrrolidone or dimethylacetamide solution containing lithium chloride.

From the chitin dope of the present invention, it is possible to create various molded products such as fibers, hollow fibers, films, nonwoven fabrics, sheets, sponges, and molded products thicker than these, and a wet molding method is preferably employed. . For example, the chitin dope of the present invention is coagulated with a ketone or alcohol that does not dissolve chitin, such as acetone, methyl ethyl ketone, methanol, ethanol, propanol, or butanol, regenerated, washed with water, dried, and stretched as necessary. By doing so, molded products such as films and fibers with excellent mechanical properties can be obtained.

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

Example 1, Comparative Example 1 Red snow crab (chione Cepes Opilio-
After thoroughly washing the exoskeleton of O′ fabricus),
Dry thoroughly in a warm air dryer at ℃, then crush in an impact crusher (Hosokawa Micron Victory Mill VP-10).
Powdered into 100 pieces. 220g of this powder
This was treated with 2N hydrochloric acid for 5 hours at room temperature, and 91 g of this was further treated with 500 ml of 2N hydrochloric acid for 2 days. After washing the treated powder with water, it was treated with 500 ml of 1N caustic soda at 100°C for 12 hours, then washed with water, and dried. To further adjust the molecular weight of the chitin obtained in this way, 1N
- treated with hydrochloric acid at 40°C for 1.5 hours. The obtained chitin was prepared using a solution of 2 g of lithium chloride dissolved in 25 g of dimethylacetamide as a solvent, and the concentration was 0.2.
g/100 g dimethylacetamide solution, the solution viscosity measured at 30° C. was 180 centipoise.

On the other hand, 100 g of an N-methylpyrrolidone solution containing saturated dissolved amount of lithium chloride was prepared at 25°C. Next, 3 g of the chitin described above was added to this solution and stirred and mixed at 25°C to obtain a viscous solution. Add another 0.5 g of lithium chloride to this solution, stir and mix thoroughly again, and then
It was filtered through a mesh stainless steel net and defoamed to obtain a transparent and viscous dope. During this filtration, no lithium chloride accumulated on the net. The dope thus obtained was placed in a tank and pumped at 25°C using a gear pump.
After discharging into isobutanol at 70℃ from the hole nozzle and coagulating in isobutanol for about 2 seconds,
It was wound at a speed of 10 m/min to obtain fibers with a total denier of 65 d. The dry strength of the obtained chitin fiber is 4.18
It was g/d.

For comparison, fibers were obtained in the same manner as in Example 1, except that a dope consisting of 3 g of chitin, 100 g of N-methylpyrrolidone, and 5 g of lithium chloride was used.
The obtained chitin fiber has a total denier of 66d,
The dry strength was 3.10 g/d.

Example 2, Comparative Example 2 The chitin purified in Example 1 before its molecular weight was adjusted was treated with 1N hydrochloric acid at 50°C for 30 minutes. The obtained chitin was prepared by adding 2 g of lithium chloride to 25
The solution viscosity of the solution measured at 30° C. was 195 centipoise using a solution of 0.2 g/100 g of dimethylacetamide as a solvent. 6 g of this chitin was dissolved at 30° C. in 200 g of a dimethylacetamide solution containing a saturated amount of lithium chloride to obtain a viscous dope. Add 1.0g of lithium chloride to this dope and mix with stirring.
A transparent and viscous dope was obtained by filtration and defoaming. This dope was cast onto a glass plate at 30°C.
After coagulating with methanol and washing with water and drying, a transparent and tough film was obtained. The strength of the obtained film was 11.5 Kg/mm ² .

For comparison, when a chitin dope with the same concentration as in Example 2 was prepared, except that a solution of 6 g of chitin dissolved in 200 g of dimethylacetamide solution containing 5% by weight of lithium chloride was used as the dope, Example 2 using a 1480 mesh unit was prepared. A film was made in the same manner. In this case, the filtration performance with the 1480 mesh unit was poor, and even after defoaming, the dope had poor transparency, and the resulting film contained what was considered to be a gelled product, resulting in poor transparency. The strength of the obtained film was 3.4 Kg/mm ² .

Claims (1)

[Claims] 1 In a chitin dope consisting of (A) chitin, (B) lithium chloride, and (C) N-methylpyrrolidone or dimethylacetamide, the amount of lithium chloride that exceeds the saturated amount dissolved in N-methylpyrrolidone or dimethylacetamide is contained. Chitin dope is characterized by: