JPH0213044B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing high-quality chitin molded articles. 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 decomposed in vivo and absorbed into tissues, and that it has good dyeability.Therefore, it has been proposed that chitin be made into fibers and used as absorbable surgical sutures. has been done. The common method for molding chitin is to wet mold a dope made by dissolving chitin in a solvent.
This solvent may be dimethylacetamide or N
-Mixtures of methylpyrrolidone and lithium chloride are known and are particularly suitable solvents for chitin, which is difficult to select. It is also known to use ketones or alcohol as a coagulation bath for wet molding of chitin. However, the conventionally known wet molding methods have not been fully satisfactory as wet molding methods for obtaining molded products with good moldability and excellent mechanical properties from chitin dope. The inventors of the present invention have conducted extensive research in consideration of the actual situation, and have found that by coagulating a specific chitin dope with a specific alcohol at 60 to 90°C, extremely satisfactory results were obtained in terms of moldability and mechanical properties. The present invention has been developed based on the discovery that this can be achieved. That is, the present invention provides a method for producing a chitin molded article by a wet method from a chitin dope consisting of chitin, dimethylacetamide or N-methylpyrrolidone, and lithium chloride. This is a method for producing chitin molded articles, characterized by discharging the chitin dope into a coagulation bath made of alcohol and having a temperature of 60 to 90°C and coagulating it. The chitin used in the present invention includes not only chitin itself but also chitin derivatives. Examples of its derivatives include carboxymethylated chitin,
Examples include etherified chitin such as hydroxyethylated chitin, esterified chitin such as acetylated chitin, and sulfonated chitin. Examples of esterified products include formic acid, acetic acid, butyric acid, valeric acid, isobutyric acid, isovaleric acid, benzoic acid,
Examples include carboxylic acids such as cinnamic acid, salicylic acid, anthranilic acid, and phthalic acid, sulfonic acids such as sulfuric acid, toluenesulfonic acid, and sulfanilic acid, carbonates, and esterified products of their anhydrides. The chitin used in the present invention has a solution viscosity (hereinafter abbreviated as solution viscosity) measured at 30°C at a concentration of 0.2g/100g dimethylacetamide using a solution of 2g of lithium chloride dissolved in 25g of dimethylacetamide as a solvent. is preferably 50 cps or more, more preferably 50 to 600 cps, and even more preferably 80 to 600 cps.
400 cps, more preferably 100 to 300 cps. Solution viscosity is measured with a B-type viscometer. The chitin solvent used in the present invention is a mixture of dimethylacetamide or N-methylpyrrolidone and lithium chloride, preferably 2% by weight or more of lithium chloride dissolved in the amide. The chitin dope used in the present invention is prepared by dissolving chitin preferably in an amount of 2 to 10% by weight in these solvents, filtering,
It can be prepared by defoaming. In the present invention, the coagulation bath is made of an alcohol selected from the group consisting of propyl alcohol, butyl alcohol, and amyl alcohol, and has a temperature of 60 to 90°C. Specific examples of propyl alcohol include 1-propanol, 2-propanol,
Specific examples of propanol and butyl alcohol include n-butyl alcohol (1-butanol, 2-butanol,
Specific examples of amyl alcohol include n-amyl alcohol, sec-amyl alcohol, tert-amyl alcohol, isoamyl alcohol, sec-isoamyl alcohol, activated amyl alcohol, Examples include diethyl carbinol and tert-butyl carbinol. Among these alcohols, e.g.
For substances with boiling points below 90°C, such as tert-butyl alcohol and isopropyl alcohol, they are used at temperatures below that boiling point. Coagulation bath temperature is 60
If the temperature is lower than 90°C or higher than 90°C, moldability will be poor and the resulting molded product will have poor mechanical properties. In the present invention, conventionally known methods and devices are appropriately selected and used for wet molding. According to the method of the present invention, chitin molded articles such as fibers, films, sheets, and tapes can be molded with extremely good moldability. For example, when producing chitin fibers, the spinning speed can be increased without yarn breakage. Furthermore, chitin molded articles with excellent mechanical properties can be obtained. The present invention will be explained in more detail below by giving examples. Example 1 Red snow crab (Chione Cepes Opilio)
o′fabricus) exoskeleton was thoroughly washed with water, and then heated to 40°C.
Thoroughly dry in a warm air dryer, then grind to 100% in an impact crusher (Hosokawa Cyclone Victory Mill VP-10).
Powdered into mesh. Add this powder at a bath ratio of 1:10.
Treated with 2N hydrochloric acid at 30°C for 5 hours, and then washed with water at 90°C with 1N caustic soda at a bath ratio of 1:
10 for 5 hours, followed by washing with water and drying.
The viscosity of the chitin solution obtained in this way is
It was 600cps. This chitin was dissolved in a dimethylacetamide solution containing lithium chloride [dimethylacetamide/lithium chloride = 25/2 (weight ratio)] at room temperature to a concentration of 3.5wt%, and filtered and defoamed to make it transparent and viscous. I got some dope. This dope was put into a tank and pumped using a gear pump at an air pressure of 5 kg/ ^cm2 , then discharged through a 0.08 mmφ, 50-hole nozzle into isobutyl alcohol heated to 70°C, solidified, and then rolled at a speed of 7 m/min. I picked it up at. The immersion length in the coagulation bath was 1 m.
The collected yarn was wound without tension in a winder. The wound yarn was immersed in methanol to sufficiently remove the solvent contained in the yarn, and then dried to obtain chitin fibers. The obtained chitin fiber had a single denier of 58 d and a dry strength of 4.02 g/d. Comparative Examples 1 to 5 Spinning was carried out in the same manner as in Example 1, except that acetone, methanol, ethanol, methyl ethyl ketone, and water were used instead of isobutyl alcohol as the coagulation bath, and each was used at a temperature approximately 15°C lower than the boiling point. . The take-up speed and the strength of the obtained yarn were as shown in Table 1. As is clear from Table 1, the take-up speed of all of the comparative examples was significantly lower than that of Example 1, and the strength of the obtained fibers was also low.

[Table] Examples 2 to 4, Comparative Examples 6 to 8 600 cps of chitin obtained in Example 1 was further added to 1N
- Solution viscosity is 332 after treatment with hydrochloric acid at 40℃ for 1 hour
Obtained centipoise chitin. This chitin was dissolved in an N-methylprolidone solution containing lithium chloride [N-methylpyrrolidone/lithium chloride = 25/2].
(weight ratio)] at a concentration of 4.0 wt% at room temperature and filtered and defoamed to obtain a transparent and viscous dope. This dope was put into a tank, and under a pressure of 5Kg/ ^cm2 , the diameter was 0.09mm.
It is discharged into 1-butanol from a 30-hole nozzle, solidified, and taken off with a roll at a speed of 5 m/min.
It was rolled up and washed without tension. At that time, the temperature of the coagulation bath was changed from 45°C to 95°C at 10°C intervals, and the spinnability and strength of the obtained yarn were measured. The results were as shown in Table 2. At low temperatures below 60°C, spinnability was poor, while at temperatures above 90°C, yarn breakage occurred due to nozzle clogging. In addition, the strength of the comparative example was lower than that of the example.

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Claims (1)

[Claims] 1. When producing a chitin molded article by a wet method from a chitin dope consisting of chitin, dimethylacetamide or N-methylpyrrolidone, and lithium chloride, an alcohol consisting of an alcohol selected from the group consisting of propyl alcohol, butyl alcohol, and amyl alcohol, A method for producing a chitin molded article, characterized in that the chitin dope is discharged into a coagulation bath at a temperature of 60° to 90°C and coagulated.