JPS627287B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a method for producing chitin fibers, and more particularly to chitin fibers having high strength and flexibility, and particularly suitable for the preparation of absorbable surgical sutures, and a method for producing the same. Chitin is a polysaccharide consisting of poly(N-acetyl-D-glucosamine), a substance widely distributed in nature such as the exoskeleton of crustaceans, and has one aminoacetyl group in each repeating unit of its molecule. It has many interesting and unique properties. One of its properties is that it undergoes enzymatic decomposition within the human body and is absorbed into tissues, and that it has good dyeability.For this reason, chitin is turned into fibers and used as absorbable surgical sutures. It is proposed to do so. Absorbable surgical sutures must have good biocompatibility, be absorbed after retaining their strength within the body for a certain period of time, and be sterilizable, as well as being easy to sew and tie. It must be easy to use and have suitable physical properties as a suture thread, such as tensile strength and flexibility. Sutures are usually manufactured by twisting multiple fibers and then knitting or braiding them, but in order for sutures to satisfy the above performance, they must be particularly usable as described above. In order to have good properties and appropriate physical properties as a suture thread, at least the fibers constituting it need to have appropriate strength and thickness. Specifically, the fibers need to have a dry strength of at least 2 g/d and a thickness of 20 denier or less, preferably 0.5 to 20 denier. In the past, various proposals have been made to produce fibers by wet spinning a chitin solution, but at present no fibers have been obtained that have both the above-mentioned properties of strength and thickness. For example, JP-A-51-133367 discloses that a chitin dope was prepared by dissolving chitin in a solution containing trichloroacetic acid, which was wet-spun and then cold-stretched to obtain highly strong chitin fibers. However, the obtained fibers are very thick. In other words, Example 2 shows that a filament with a tensile strength of 63 kg/mm ² was obtained, and this value is equivalent to 5 g/d when the density is calculated as 1.4, which is a high-strength chitin. It is clear that fibers have been obtained, but the diameter of the fibers is 0.25 mm as seen in Example 3, which corresponds to 618 denier when calculated with a density of 1.4. , does not satisfy the above conditions. Additionally, JP-A-53-127500 describes that chitin dope was prepared by dissolving chitin in a solvent such as dichloroacetic acid, which was wet-spun and then drawn to obtain fine denier chitin fibers. However, the strength of the obtained fibers is low. That is, although the example shows that chitin fibers of 3.0 to 3.5 deniers were obtained, the strength thereof was 1.2 to 1.5 g/d, which does not satisfy the above conditions. As described above, chitin fibers having sufficient strength and flexibility, that is, appropriate thickness, to be used for preparing surgical suture threads have not been known so far. In view of the current situation, the present inventors have developed a fiber having sufficient strength and sufficient flexibility, that is, an appropriate thickness, to be used in the preparation of surgical sutures, and more specifically, a fiber having a thickness of at least 2 g/d. Strength and 0.5~
As a result of extensive research with the aim of providing chitin fibers with a thickness of 20 denier, the above objective was achieved by further treating the threads formed in a coagulation bath in a free state with a coagulation solution. We have discovered what can be achieved and arrived at the present invention. That is, the present invention, when producing chitin fiber by wet spinning a chitin dope consisting of chitin and a solvent, extrudes the chitin dope through a nozzle into a coagulation bath and takes it out to form a thread containing the solvent. This method of producing chitin fibers is characterized in that the obtained yarn is treated with a coagulating liquid in a state where substantially no tension is applied to the yarn. Chitin in the present invention includes not only chitin itself but also chitin derivatives. Chitin used in the present invention can be prepared by, for example, treating crustaceans, insects, etc. with hydrochloric acid and caustic soda to separate and purify protein and calcium components, or by etherifying, esterifying, etc. can do. Examples of chitin derivatives used in the present invention include etherified chitin such as carboxymethylated chicken, hydroxyethylated chitin, acetylated chitin,
Examples include esterified chitin such as sulfonated chitin. Examples of esterified products include formic acid,
Carboxylic acids such as acetic acid, butyric acid, valeric acid, isobutyric acid, isovaleric acid, benzoic acid, cinnamic acid, salicylic acid, anthranilic acid, phthalic acid, sulfonic acids such as sulfuric acid, toluenesulfonic acid, sulfanilic acid, carbonates, or the like. Examples include esterified products of anhydrides. To prepare these esterified products, for example, chitin powder may be treated with the above-mentioned acids or their aqueous solutions, and if necessary, sulfuric acid, hydrochloric acid, toluenesulfonic acid, etc. can also be used as a catalyst. The degree of esterification can be adjusted by changing the composition, temperature, or treatment time of the treatment solution. For example, acetylation can be carried out in a relatively short time. For example, chitin powder is soaked in 90% acetic acid for 10 minutes at room temperature, thoroughly washed with water, then neutralized with ammonium hydroxide to completely remove free acetic acid, and dried to achieve an acetylation degree of approximately 6%. Acetylated chitin can be prepared. In the present invention, various known chitin solvents can be used as the solvent for preparing the chitin dope, but trichloroacetic acid is preferably used. Since the melting point of trichloroacetic acid is 57°C, it is necessary to maintain the temperature at least above 57°C in order to obtain chitin dope. Since chitin decomposes to some extent at such temperatures, it is desirable to use trichloroacetic acid as a solvent together with an organic solvent that can dissolve trichloroacetic acid, preferably at 50° C. or lower, more preferably at room temperature or lower. Examples of solvents that can dissolve trichloroacetic acid and provide a uniform chitin dope at room temperature include chlorinated hydrocarbons. Preferred chlorinated hydrocarbons include, for example, chloromethane, dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, etc., and these may be used alone. They may be used alone, or two or more kinds may be used in combination. The mixing ratio of trichloroacetic acid and chlorinated hydrocarbon is 25~
The range of 75:75 to 25 (weight ratio) is preferable. The higher the proportion of trichloroacetic acid, the better the solubility of chitin, but in order to avoid a decrease in the molecular weight due to the decomposition of chitin, the above range in which the mixed solvent is liquid at room temperature or lower is preferable. In the present invention, the chitin dope is
For example, it can be prepared as follows. That is, when only trichloroacetic acid is used as a solvent, chitin powder may be gradually added while heating the trichloroacetic acid to at least 57°C or higher, and the chitin powder may be stirred and mixed to dissolve it. In addition, when using a mixed solvent of trichloroacetic acid and chlorinated hydrocarbon as a solvent, add and mix trichloroacetic acid to the chlorinated hydrocarbon in advance to obtain a liquid mixed solvent at as low a temperature as possible, preferably below 10°C. Chitin powder may be gradually added to the mixed solvent and dissolved by stirring and mixing. The concentration of chitin in the chitin dope is preferably 0.5-20% by weight, more preferably 0.5-10% by weight, even more preferably 1-10% by weight. If the concentration of chitin becomes too high, it will be difficult to dissolve and produce fibers from such a chitin dope, while if it becomes too low, it will be difficult to obtain fibers with excellent mechanical properties, which is undesirable. In the present invention, additives such as dyes, pigments, stabilizers, antioxidants, heat resistant agents, bactericides, preservatives, anesthetics, and fillers may be added to the chitin dope as necessary. To produce chitin fibers by the method of the present invention, it is first necessary to extrude the chitin dope prepared as described above into a coagulation bath through a nozzle and take it off to form a thread containing a solvent. It is. Examples of coagulation baths include organic ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, diethyl ketone, and cyclopentanone, chlorinated hydrocarbons such as ethylene chloride, carbon tetrachloride, trichlorethylene, and tetrahydrofuran, cyclohexane, hexane, and petroleum ether. hydrocarbons such as methanol, ethanol, isopropyl alcohol, n-butyl alcohol, esters such as ethyl acetate,
Amides such as dimethylformamide and N-methylpyrrolidone can be used, but anhydrous acetone, anhydrous methanol, or anhydrous ethanol are particularly preferred. The temperature of the coagulation bath is 10~
A temperature of about 25°C is suitable. The chitin dope is filtered and defoamed if necessary, and then extruded from a nozzle into a coagulation bath and taken off. For this purpose, a conventional wet spinning device and method can be employed. At this time, it is necessary that the yarn taken off contains a solvent, that is, is in an incompletely coagulated state. In the present invention, it is necessary to treat the yarn formed as described above with a coagulating liquid in a state where substantially no tension is applied to the yarn. As mentioned above, the taken yarn still contains some solvent, but in order to treat it with a coagulation liquid in a state where no tension is applied, for example, after spinning, Coagulation bath (first coagulation bath)
It is possible to adopt a method in which the yarn taken up by a roll through the steps is introduced into a second coagulation bath and treated. In order to show this method more specifically, one embodiment is shown in FIG. In FIG. 1, a yarn 1a is extruded from a nozzle into a first coagulation bath and then taken up by a roller, and is shaken off from an introduction roller 2 onto a conveyor 3 to form a yarn pile 1b. The conveyor 3 is in the second coagulation bath 4 and is moving at a speed slower than the introduction speed of the yarn 1a, and after the yarn is coagulated in the second coagulation bath 4, it is returned from the yarn pile 1b to the yarn 1c. It is returned to the state shown in FIG. Further, another embodiment is shown in FIG. In Fig. 2, a yarn 1 is extruded from a nozzle into a first coagulation bath and then taken off by a roller.
A is dropped by an introduction roller 2 into a device having the shape of a curved pipe capable of stuffing yarn, such as a U-shaped tube 6, and is laminated. The U-shaped tube 6 is filled with a coagulating liquid, and the yarn is moved to the other opening of the U-shaped tube 6 due to the lamination pressure and coagulated, and then returned to the state of the yarn 1c and pulled. Take-off roller 5
It will be taken over by. In the present invention, it is possible to provide a plurality of second coagulation baths, and it is also possible to provide a plurality of second coagulation baths.
It is possible to stack the yarn introduced into the coagulation bath as it is in the coagulation bath and then take it off, or it is also possible to treat the yarn in the first coagulation bath without providing a second coagulation bath. Any method can be used as long as it can be processed without substantially applying tension to the strip. As the coagulating liquid used in this treatment, those used in the above-mentioned coagulating bath (spinning bath) can be used. In the present invention, when performing the treatment with the above-mentioned coagulation liquid, the residual amount of solvent in the yarn is 10 to 50% before treatment.
% by weight (based on the polymer), preferably in a range of 10% by weight or less after treatment. It is desirable that the treatment time is 1 minute or more, particularly 10 minutes or more. Another preferred method is to leave it for one night or more. The fibers obtained as described above have a dry strength of 2 g/d or more as is, but by stretching them, fibers with even higher strength can be obtained. Stretching may be carried out subsequent to treatment with a coagulating solution, or may be carried out after neutralization and washing, and various known devices may be used; be able to. The yarn treated with the coagulation liquid is neutralized, washed, and dried as necessary. Various known devices and methods can be used for neutralization, washing, and drying. As described above, according to the present invention, the single yarn has a denier of 0.5 to 20 denier, and at least 2 g/
It is possible to obtain chitin fibers having a dry strength of d, preferably 2.5 g/d or more, more preferably 3 g/d or more, even more preferably 3.5 g/d or more, which is particularly useful for absorbable surgical sutures. It is preferred as a fiber for preparing yarn. The chitin fibers obtained by the method of the present invention have a total denier of, for example, 30 to 200 deniers and can be used as clothing yarns or special yarns, as well as knitted fabrics and woven fabrics. The present invention will be explained in more detail below by giving examples. In addition, the dry strength in the example is 25℃, 60%RH
It was measured using an Instron tensile tester under controlled humidity. Example 1, Comparative Examples 1 and 2 Chitin powder [manufactured by Kyowa Yushi Co., Ltd., degree of polymerization approximately 1 million]
A chitin dope was obtained by dissolving 3 parts by weight in a mixed solvent consisting of 50 parts by weight of trichloroacetic acid and 50 parts by weight of methylene chloride at 5°C. The dope obtained was a clear and viscous solution. This dope was filtered under a pressure of 4 kg/cm ² using a stainless wire mesh of 1480 mesh, and then thoroughly defoamed under reduced pressure. After the defoamed dope was transferred to a tank, it was pumped with a gear pump under a pressure of 2.5 kg/cm ² to form a hole with a pore diameter of 0.08 mm and 40 holes.
The yarn was spun into acetone (first coagulation bath) whose temperature was controlled at 14° C. at a discharge rate of 2.3 ml/min from a nozzle, and the yarn was drawn onto a roller at a speed of 10 m/min. The collected yarn is then guided to the device shown in Figure 1, and 15
In methanol (second coagulation bath) whose temperature was controlled to ℃,
After processing for 5 minutes on a conveyor moving at a speed of 0.5 m/min, it was wound up into a winder at a speed of 9 m/min. The wound yarn was immersed in a caustic soda aqueous solution with a concentration of 0.3 g for 1 hour to neutralize it, then washed with ion-exchanged water until the pH of the washing water became neutral, and then dehydrated with a centrifugal dehydrator. Chitin fibers were obtained by drying under reduced pressure at room temperature overnight (sample A). The results of measuring the denier, dry strength and residual elongation of the obtained chitin fibers are shown in Table 1. For comparison, without using a belt conveyor,
Chitin fibers were obtained in the same manner as in Example 1, except that the fibers were simply passed through the second coagulation bath under tension (Sample B). In addition, instead of using a belt conveyor, a parallel pair of rollers with the roller part immersed in the coagulation bath is installed in the second coagulation bath, and the yarn is wound around this pair of rollers 20 times to process it in a tensioned state. Chitin fibers were obtained in the same manner as in Example 1 except for the above (Sample C). The performance of the obtained Samples B and C was measured in the same manner as Sample A. The results were as shown in Table 1.

[Table] Take 12 pieces of sample A and make a braid, USP
A suture with a thickness of 3-0 was created using the × version collagen suture standard. The tensile strength of the obtained suture was 2.41 kg, and the knot tensile strength, which is the standard for tensile strength in the Japanese Pharmacopoeia, was 1.87 kg.
1.25Kg or more). In addition, this material was flexible and easy to handle, and could be fully used as a surgical suture thread. On the other hand, we tried to make a braid using Samples B and C in the same way as Sample A, but due to the low strength of the fibers, the threads were severed during the braiding process, and we were unable to make a good braid. I couldn't get the string. Examples 2 to 6 The same dope as in Example 1 was used, and the same filtration and defoaming as in Example 1 were carried out. After the defoamed dope was transferred to a tank, under a pressure of 2.5 kg/cm ² , the methanol was pumped using a gear pump and the temperature was controlled at 16°C at a discharge rate of 2.5 ml/min from a nozzle with a hole diameter of 0.07 mm and 30 holes. (first coagulation bath) to form a yarn;
It was taken up by rollers at a speed of 15 m/min. The drawn yarn was subsequently immersed in methanol (second coagulation bath) containing 0.3 g of caustic soda in a substantially free and tension-free state. The soaked yarn was removed from the bath at intervals of 1 minute (Example 2), 10 minutes (Example 3), 1 hour (Example 4), 10 hours (Example 5), and 24 hours (Example 6). Take out, 0.5 each
After neutralizing for about 1 hour with a caustic soda aqueous solution with a concentration of 1.5 g/g, the mixture was washed repeatedly with ion-exchanged water until the washing water became neutral, then dehydrated using a centrifugal dehydrator, and dried under reduced pressure at room temperature overnight. Seed chitin fibers were obtained.
The results of measuring the denier, dry strength and residual elongation of the obtained chitin fibers are shown in Table 2. In addition, all the fibers of Examples 2 to 6 were silk-like fibers. When we attempted to create a suture using these fibers in the same manner as in Example 1, we found that the suture was easy to create, and the resulting suture had sufficient tensile strength and knot strength. It was flexible and easy to handle, and was satisfactory as a surgical suture thread.

[Table] Comparative Example 3 Chitin powder [manufactured by Kyowa Yushi Co., Ltd., degree of polymerization approximately 1 million]
A chitin dope was obtained by dissolving 6 parts by weight in a mixed solvent consisting of 50 parts by weight of trichloroacetic acid and 50 parts by weight of dichloromethane at 0°C. The dope obtained was a clear and viscous solution. This dope was filtered under a pressure of 6 kg/cm ² using an 800 mesh stainless steel wire mesh, and then thoroughly defoamed under reduced pressure. After the defoamed dope was transferred to a tank, it was pumped with a gear pump under a pressure of 4 kg/cm ² and acetone (humidified at 14°C) was discharged from a nozzle with a hole diameter of 0.4 mm and 2 holes at a discharge rate of 2.5 ml/min. The yarn was spun into a coagulation bath (1 coagulation bath) to form a yarn, which was taken up by rollers at a speed of 8 m/min. The taken yarn was then immersed in methanol (second coagulation liquid) containing 0.3 g of caustic soda and neutralized for 1 hour, then taken out from the bath and washed with ion-exchanged water. The fibers were then dehydrated using a centrifugal dehydrator and dried under reduced pressure at room temperature overnight to obtain chitin fibers. The obtained fiber is 71d
(single yarn denier 35.5 d), dry strength 2.9 g/d, and residual elongation 26%. Twelve of these fibers were braided in the same manner as in Example 1, and were rated at 3-0 according to the US Pharmacopoeia XX edition collagen suture standard.
However, the texture of the obtained material was extremely hard and stiff, making it difficult to use as a suture.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams showing one embodiment of the present invention. 1a, 1b, 1c... yarn, 2... introduction roller, 3... conveyor, 4... second coagulation bath, 5...
...Take-up roller, 6...U-shaped tube.

Claims (1)

[Scope of Claims] 1. When manufacturing chitin fiber by wet spinning a chitin dope consisting of chitin and a solvent, the chitin dope is extruded through a nozzle into a coagulation bath and taken off to form a thread containing a solvent, A method for producing chitin fibers, which comprises treating the formed threads with a coagulating liquid in a state where no tension is substantially applied to the threads. 2. The manufacturing method according to claim 1, wherein the solvent is trichloroacetic acid. 3. The manufacturing method according to claim 1, wherein the solvent is a mixture of trichloroacetic acid and a chlorinated hydrocarbon. 4. The manufacturing method according to claim 1, wherein the formed thread is treated with a coagulating liquid using a belt conveyor. 5. The manufacturing method according to claim 1, wherein the formed yarn is treated with a coagulating liquid using a device having a curved pipe shape capable of stuffing the yarn. 6. The manufacturing method according to claim 1, which comprises treating with a coagulating solution for at least 1 minute.