JPH0343371B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hollow fibers made of chitin and a method for producing the same, and more specifically to hollow fibers made of chitin, of high quality, which have high strength during use and are easy to handle. The present invention relates to a manufacturing method thereof.

Chitin is a substance that is widely distributed in nature, such as the exoskeleton of polysaccharides made of poly(N-acetyl-D-glycosamine), and has one aminoacetyl group in each repeating unit of its molecule, so it has many It has interesting and unique properties. One of these properties is that it undergoes enzymatic decomposition in vivo and is absorbed into tissues. Furthermore, chitin is a highly hydrophilic substance and is excellent as an adsorbent for proteins and sugars, and if made into a porous structure, it can be used as a semipermeable membrane. Therefore, hollow fibers can be considered as one form that utilizes these properties. However, until now, hollow fibers that can be advantageously used industrially have not been obtained.

The common method for molding chitin is to wet mold a dope made by dissolving chitin in a solvent.
As this solvent, for example, a mixture of dimethylacetamide or N-methylpyrrolidone and lithium chloride, formic acid, dichloroacetic acid, trichloroacetic acid, etc. are known. Among these, JP-A-52-
Dimethylacetamide containing about 5% by weight of lithium chloride or N-
Methylpyrrolidone solution is an extremely good solvent for chitin because it causes little decomposition of chitin.

On the other hand, various methods are known for the purification of chitin, including the method described in "chitin" P.90 (1977) by Riccadoa.A.Muzzarelli, published by Pergamon Press. 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 0.2 g/100 using a solution of 2 g of lithium chloride dissolved in 25 g of dimethylacetamide as a solvent.
g dimethylacetamide solution, exceeds 800 centipoise when measured at 30°C. The viscosity of this solution varies depending on the type of crustacean used as a raw material and the refining conditions, but unless harsh conditions are used,
It will never fall below 800 centipoise. When a molding dope is prepared using such chitin, the viscosity of the dope becomes high even if the solvent described in JP-A-52-100499 is used.
Wet molding is difficult, and molded products with sufficient performance cannot be obtained. For these reasons, conventionally only fibers and films with low strength or large thickness have been obtained, and it has been difficult to obtain molded products with special shapes such as hollow fibers and excellent performance. It was extremely difficult.

As a result of intensive research to obtain hollow fibers from chitin that can be advantageously used industrially, the present inventors have found that
The fact that hollow fibers with a strength of 0.5 g/d or more, an inner diameter of 50 to 100 μm, and a membrane thickness of 5 to 200 μm is preferably used for various uses including membrane separation, and that such hollow fibers are specified The present invention was achieved by discovering the fact that chitin can be obtained by wet molding using chitin having a solution viscosity of .

That is, the present invention provides (1) hollow fibers made of chitin having a dry strength of 0.5 g/d or more, an inner diameter of 50 to 100 μm, and a film thickness of 5 to 200 μm, and (2) a double tube containing a solution of chitin in an organic solvent. The structure is extruded through the annular slit in the outer tube of the spinneret, and a solution containing a non-solvent of chitin is injected as a core material from the inner tube of the spinneret to form a hollow stock solution, which is then introduced into a coagulating solution to form hollow fibers. After forming, when producing hollow fibers made of chitin by washing, a solution of 2 g of lithium chloride dissolved in 25 g of dimethylacetamide was used as the solvent, and a chitin solution with a concentration of 0.2% by weight was heated at 30°C. (3) A method for producing hollow fibers made of chitin, characterized in that chitin having a solution viscosity in the range of 50 to 800 centipoise is used; The gist of the invention is a hollow fiber made of chitin according to item 1 of the scope.

The chitin used in the present invention includes not only chitin itself but also chitin derivatives. Such chitin can be prepared by treating the exoskeleton of crustaceans, insects, etc. with acid and caustic soda to separate and purify the protein and calcium components. Examples of chitin derivatives include those partially converted to chitosan by deacetylation, etherified chitins such as carboxymethylated chitin and hydroxyethylated chitin, and esterified chitins such as acetylated chitin and sulfonated chitin. It will be done. Examples of esterified products include formic acid, acetic acid, butyric acid, valeric acid, isobutyric acid, isovaleric acid, benzoic acid, cinnamic acid, salicylic acid, anthranilic acid,
Examples include carboxylic acids such as phthalic acid, sulfonic acids such as sulfuric acid, toluenesulfonic acid, and sulfanilic acid, and esterified products of their anhydrides.

The chitin used in the present invention is 2g of lithium chloride.
The solution viscosity measured at 30℃ is 50-800 centipoise using a solution of 25g of dimethylacetamide as a solvent. Preferably it is between 80 and 400 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 acid treatment 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 "Methcd of Hackman" has a solution viscosity exceeding 800 centipoise, but in order to obtain chitin having the solution viscosity of the present invention, such chitin is treated with hydrochloric acid as follows. Just go. That is, by treating chitin with a solution viscosity of 1000 centipoise with 1/2N hydrochloric acid at 60℃ for 30 minutes, approximately 100 centipoise of chitin can be treated with 1N hydrochloric acid at 30℃ for 2 minutes.
Chitin of 250 centipoise can be obtained by processing for 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 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, generally known solvents such as trichloroacetic acid, dichloroacetic acid, N-methylpyrrolidone, or a mixture of dimethylacetamide and lithium chloride can be used as the organic solvent in which chitin can be dissolved. −
From 55% by weight or more to methylpyrrolidone or dimethylacetamide to 0.5% by weight from the saturated dissolved amount
Those containing less than a small amount can be preferably used. The saturated solution amount herein means the saturated solution amount of lithium chloride in N-methylpyrrolidone or dimethylacetamide, and its value depends on the type of solvent and temperature and shows different values for each.
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. After that, 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).

As the coagulating liquid used in carrying out the present invention, any coagulating liquid can be used as long as it is mainly a non-solvent of chitin. Examples of such coagulating liquids include water, methanol, ethanol,
Examples include isopropanol, butanol, acetone, methyl ethyl ketone, and others containing some amide solvents, but alcohols are preferably used. Most chitin non-solvent core materials can be used, but in order to avoid problems such as deformation due to pulsation near the spinneret and destruction of the hollow part during extrusion of the hollow stock solution, it is necessary to use a core material with slow coagulation ability. For example, fatty acid esters are preferably used. Specific examples of fatty acid esters include those with a total carbon number of 4 to 30;
For example, methyl oleate, methyl laurate,
Examples include oleyl oleate, sorbitan oleate, isopropyl stearate, isopropyl myristate, monomethyl azelate, dimethyl azelate, dodecyl acetate, and decyl propionate.

To produce chitin hollow fibers by the method of the present invention, an organic solvent solution of chitin is discharged from an outer tube with a double tube structure, and a core material is injected through a double inner tube, and the solution is directly coagulated from a spinneret. The hollow stock solution is extruded into a spinneret, or as is often done when manufacturing cellulose hollow fibers, the hollow stock solution discharged from the spinneret surface is introduced into an inert gas such as air and subjected to a high draft. Just use the method that guides you.

In order to produce hollow fibers by the method of the present invention, it is necessary to wash the hollow fibers containing the core material produced by the method described above in alcohol, hot water, or the like. Furthermore, if necessary
Stretching may be performed up to about 20 times.

According to the method of the present invention as described above, the dry strength is
0.5g/d or more, and the inner diameter in the dry state is
Hollow fibers having a thickness of 50 to 100 μm and a film thickness of 5 to 200 μm can be obtained, and homogeneous hollow fibers in which the hollow portion is located approximately at the center of the fiber cross section can be obtained. If the method of the present invention were not used, it would be impossible to form such hollow fibers, and for example, yarn breakage would occur during spinning of hollow fibers, or if the inner diameter
If the diameter is less than 1,000 μm, a sufficiently large hollow part cannot be obtained, or only one having a diameter exceeding 1000 μm can be obtained. Furthermore, the film thickness can be extremely thin, less than 5 μm, or more than 200 μm. Furthermore, the method of the present invention makes it possible to obtain practical hollow fibers for the first time, such as dry strength of less than 0.5 g/d.

The hollow fibers of the present invention can be used in many applications utilizing chitin's biodegradability, adsorption, water absorption, etc. It can be particularly preferably used as a membrane separation material.
In this case, it is necessary to create pores in the porous structure, and these pores can be created in various sizes by particularly selecting the coagulating liquid and the core material. Furthermore, if necessary, the size of the pores can be adjusted by adding a small amount of polyethylene glycol or the like to the chitin solution in an organic solvent during coagulation. Compared to commercially available cellulose, PVA, and polyacrylonitrile hollow fibers, the hollow fibers of the present invention have better water permeability when used as a filter for ultrafiltration, etc., and can perform efficient filtration. Therefore, dialysis,
It can be used as a membrane separation material for ultrafiltration and the like, and is particularly preferably used for dialysis membranes for artificial kidneys, plasma separation membranes, etc.

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

Example 1 Red snow crab (chione cepes opilio-o
After thoroughly washing the exoskeleton of the exoskeleton with water, it was thoroughly dried in a hot air dryer at 40°C, and then it was pulverized into 100 meshes using an impact pulverizer (Hosokawa Micron Victory Mill VP-10). 220g of this powder
- treated with hydrochloric acid at room temperature for 5 hours;
91 g was treated with 500 ml of 2N hydrochloric acid for 2 days. After washing the treated powder with water, it was treated with 500ml of 1N caustic soda at 100℃ for 12 hours, then washed with water,
I did drying. The chitin thus obtained was treated with 1N hydrochloric acid at 40°C for 1 hour to further adjust the molecular weight. This chitin had a solution viscosity of 350 centipoise 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.

On the other hand, at 25°C, a solution was prepared in which 8% by weight of lithium chloride was added to 200g of N-methylpyrrolidone.

To this solution, 10 g of the above chitin was added, thoroughly stirred and mixed, filtered through a 1480 mesh stainless steel net, and defoamed to obtain a transparent and viscous dope.

This dope is supplied at a rate of 5 g/min to the outer tube part of a spinning nozzle that has a double tube structure, the inner diameter of the outer tube part is 6 mm, the outer diameter of the inner tube part is 4 mm, and the same inner diameter is 1 mm. On the other hand, methyl oleate was supplied as a core material to the inner tube at a rate of 5.5 g/min. The hollow stock solution that had passed through the spinning nozzle was passed through the air for 2 cm while being drafted, and then introduced into an isobutanol coagulation solution at 65°C to solidify it.
It was wound up at a speed of 10 min, and then thoroughly washed in hot water at 90°C.

The obtained hollow fibers have an almost perfect circular shape and an outer diameter of
312μm, inner diameter 286μm, dry strength 1.2g/d
It was hot.

When the permeation performance of this hollow fiber was measured, urea and creatinine permeated sufficiently, but albumin did not ^permeate at all ^.・ATM)
It showed good performance as an ultrafiltration membrane and a dialysis membrane.

On the other hand, the water permeation rate of a commercially available Cyprofane membrane (outer diameter 260 μm, inner diameter 201 μm) measured under the same conditions for comparison was 9×10 ^-2 cc/hr・cm ²・atm at 36°C; 250 μm, inner diameter 189 μm), it was 8×10 ^-2 cc/hr・cm ²・atm.

Comparative Example 1 The same procedure as in Example 1 was carried out, except that instead of the chitin used in Example 1, chitin with a solution viscosity of 1050 centipoise before adjusting the degree of polymerization was used, and the amount used was changed from 10 g to 8 g. Although spinning was performed, the hollow portion was eccentric and partially torn, making it impossible to obtain a satisfactory hollow fiber.

Comparative Example 2 Chitin with a solution viscosity of 1050 centipoise used in Comparative Example 1 was further diluted with 1N to adjust the degree of polymerization.
- Treated with hydrochloric acid at 40℃ for 2 hours to reduce the viscosity of the solution.
40 centipoise of chitin was obtained. Hollow fibers were spun in the same manner as in Example 1 except that this chitin was used instead of the chitin used in Example 1.
Thread breakage was frequent and hollow fibers could not be obtained satisfactorily.

Example 2 In Example 1, the chitin treated with hydrochloric acid and alkali was further treated to adjust its molecular weight.
Treatment was performed with 1N hydrochloric acid at 50°C for 1 hour. The obtained chitin was prepared using a solution of 2 g of lithium chloride dissolved in dimethylacetamide as a solvent, at a concentration of 0.2 g/
A 100 g dimethylacetamide solution had a solution viscosity of 85 centipoise, measured at 30°C.

On the other hand, at 25°C, a solution containing 7% by weight of lithium chloride was prepared for 200g of dimethylacetamide.
12 g of the above chitin was added to this solution, thoroughly stirred and mixed, filtered through a 1480 mesh stainless steel net, and defoamed to obtain a transparent and viscous dope.

This dope has a double tube structure, the inner diameter of the outer tube is 8 mm, the outer diameter of the inner tube is 5 mm, and the inner diameter of the outer tube is 8 mm.
It was supplied to the outer tube of a 1.5 mm spinning nozzle at a rate of 8.1 g/min, while isopropyl silistate was supplied as a core material to the inner tube at a rate of 9.0 g/min. The hollow stock solution that has passed through the spinning nozzle is introduced into a methanol coagulation solution at 30°C and coagulated.
It was wound up at a speed of m/min and then thoroughly washed in hot water at 90°C.

The obtained hollow fibers have an almost perfect circular shape and an outer diameter of
The diameter was 368μ, the inner diameter was 339μ, and the dry strength was 1.5g/d. When we measured the permeation performance of this hollow fiber, urea nocreatinine permeated sufficiently, but albumin did not permeate at all, and the water permeation rate of the dry hollow fiber was 36.
15×10 ^-2 (cc/hr・cm ²・atm) at °C,
It showed good performance as an ultrafiltration and dialysis membrane.

Claims (1)

[Claims] 1. Dry strength is 0.5 g/d or more and inner diameter is 50 to 1000μ
m, hollow fibers made of chitin with a film thickness of 5 to 200 μm. 2. Extruding an organic solvent solution of chitin through an annular slit in the outer tube of a spinneret having a double tube structure, and injecting a solution containing a non-solvent of chitin as a core material from the inner tube of the spinneret to form a hollow stock solution; Subsequently, after introducing it into a coagulation solution to form hollow fibers, washing is performed to produce hollow fibers made of chitin.
As chitin, chicken is used, the solution of which is 2 g of lithium chloride dissolved in 25 g of dimethylacetamide is used as the solvent, and the chitin solution has a concentration of 0.2% by weight, and the solution viscosity at 30°C is in the range of 50 to 800 centipoise. A method for producing hollow fibers made of chitin. 3. A hollow fiber made of chitin according to claim 1 obtained by the production method according to claim 2.