JP6865136B2 - Hydrogel fiber manufacturing method - Google Patents

Description

The present invention relates to a method for producing a hydrogel fiber and a method for controlling the fiber diameter thereof.

Hydrogels are widely used in the fields of cosmetics, pharmaceuticals, quasi-drugs, foods, etc. because of their high water retention, structural flexibility, oxygen diffusivity, substance absorption, elasticity, and biocompatibility. ing. Further, unlike the hydrogel particles formed in the form of particles, the hydrogel fiber in which the hydrogel is formed in a linear shape has a very large specific surface area, strong and supple mechanical properties, and an arrangement with a high aspect ratio. It is expected that various functions will be created because of its features such as controllability and controllability of the diffusion direction of functional substances.

By the way, when an aqueous solution of sodium alginate is added to an aqueous solution of calcium chloride, an ion-crosslinked hydrogel of calcium alginate is formed by ion exchange between calcium ions and sodium ions. Hydrogel fibers can be manufactured by utilizing this property. Patent Documents 1 and 2 describe a wet spinning method in which an aqueous solution of sodium alginate is linearly discharged into an aqueous solution of calcium chloride from a nozzle, and an ion-crosslinked hydrogel of calcium alginate is formed by ion exchange between calcium ions and sodium ions. A method for producing a hydrogel fiber is disclosed.

Japanese Unexamined Patent Publication No. 62-141199 Japanese Unexamined Patent Publication No. 5-209318

However, with the techniques disclosed in Patent Documents 1 and 2, it is difficult to arbitrarily control the fiber diameter of the obtained hydrogel fiber.

An object of the present invention is to provide a method for producing a hydrogel fiber having a desired fiber diameter while suppressing fluctuations in the fiber diameter along the length direction.

In the present invention, a second aqueous solution containing a gel-forming substance that forms an ion-crosslinked hydrogel by ion exchange with the metal ions is linearly discharged into a first aqueous solution containing metal ions using a discharge means. This is a method for producing a hydrogel fiber, wherein the second aqueous solution is discharged into the first aqueous solution by the discharging means in a state where the Reynolds number is 10 or less, and the pressure loss at that time is 0.20 MPa or more. Set in the range of.

In the present invention, a second aqueous solution containing a gel-forming substance that forms an ion-crosslinked hydrogel by ion exchange with the metal ions is linearly discharged into a first aqueous solution containing metal ions by using a discharge means. This is a method of controlling the fiber diameter of the hydrogel fiber produced by the above method, in which the second aqueous solution is discharged into the first aqueous solution by the discharging means in a state where the Reynolds number is 10 or less, and the correlation with the fiber diameter. The pressure loss at that time is set to a value corresponding to the target fiber diameter in the range of 0.20 MPa or more.

According to the present invention, when the second aqueous solution is linearly discharged into the first aqueous solution by the discharging means in a state where the Reynolds number is 10 or less, the fiber diameter of the obtained hydrogel fiber has a pressure loss of 0 at that time. Since it has a correlation with the pressure loss in the range of .20 MPa or more, the fiber diameter of the hydrogel fiber obtained by the setting can be controlled. Therefore, the second aqueous solution is added to the first aqueous solution by the discharging means. If the pressure loss at the time of discharge is set to a value corresponding to the target fiber diameter in the range of 0.20 MPa or more, the fluctuation of the fiber diameter along the length direction of the hydrogel fiber having the desired fiber diameter can be suppressed. Can be manufactured.

It is a figure which shows the structure of the hydrogel fiber manufacturing system. It is sectional drawing of the tip part of a discharge nozzle. It is a graph which shows the relationship between the pressure loss for Examples 1-12 and Comparative Example 1 and the fiber diameter of the obtained hydrogel fiber.

Hereinafter, embodiments will be described in detail.

(Hydrogel Fiber Manufacturing System S)
FIG. 1 shows a hydrogel fiber manufacturing system S used in the hydrogel fiber manufacturing method according to the embodiment.

The hydrogel fiber manufacturing system S includes a fiber recovery tank 10 for storing the first aqueous solution and a second aqueous solution supply unit 20 for supplying the second aqueous solution to the fiber recovery tank 10.

The second aqueous solution supply unit 20 has a second aqueous solution storage tank 21 for storing the second aqueous solution and a second aqueous solution supply pipe 22 extending from the second aqueous solution storage tank 10 toward the fiber recovery tank 10. The second aqueous solution supply pipe 22 includes a cock 23 for switching the flow and shutoff of the second aqueous solution, a pump 24 for sending the second aqueous solution, and a flow meter 25 for detecting the flow rate of the second aqueous solution. A pressure gauge 26 for detecting the pressure of the second aqueous solution is provided on the downstream side of the flow meter 25 in order from the upstream side, and a discharge nozzle 27 (discharge) as shown in FIG. 2 is further provided at the tip. Means) are attached. The tip of the second aqueous solution supply pipe 22 to which the discharge nozzle 27 is attached is guided into the fiber recovery tank 10. The pump 24 and the flow meter 25 are electrically connected to each other, and are configured to perform feedback control of the flow rate of the second aqueous solution.

The material forming at least the portion of the discharge nozzle 27 in which the discharge hole 27a is formed is a material for producing a hydrogel fiber having a small fiber diameter by suppressing fluctuations in the fiber diameter along the length direction, as will be described later. The static contact angle with water is preferably 40 ° or more, more preferably 50 ° or more, still more preferably 60 ° or more, still more preferably 80 ° or more, and it is preferable from the viewpoint of being an easily available material. Is 180 ° or less, more preferably 120 ° or less, still more preferably 110 ° or less. The static contact angle with respect to water is measured 6 seconds after the water droplets of 10 μL of ion-exchanged water are dropped on the surface of the material using an automatic contact angle meter DM-500 manufactured by Kyowa Interface Science Co., Ltd. is there.

Examples of the material forming at least the portion of the discharge nozzle 27 in which the discharge hole 27a is formed include a fluororesin such as polytetrafluoroethylene (PTFE) and an alloy such as stainless steel (SUS) and brass. From the viewpoint of suppressing fluctuations in the fiber diameter along the length direction to produce a hydrogel fiber having a small fiber diameter, a fluororesin is preferable, and polytetrafluoroethylene is more preferable.

As for the discharge nozzle 27, it is preferable that the inner wall 27b of the flow path of the second aqueous solution continuous with the discharge hole 27a is also formed of the above material. It is preferable that the peripheral portion 27c of the discharge nozzle 27, which is continuous from the discharge hole 27a to the outside, is also made of the above material. The entire nozzle of the discharge nozzle 27 may be made of the above material. Alternatively, the discharge nozzle 27 may have a nozzle body made of a metal such as stainless steel, and at least a portion of the surface thereof corresponding to the discharge hole 27a may be coated with a fluororesin.

The number of discharge holes of the discharge nozzle 27 may be singular or plural. The discharge hole diameter of the discharge hole 27a of the discharge nozzle 27 is preferably 0.010 mm or more, more preferably 0.10 mm or more, still more preferably 0.15 mm or more, and preferably 5.0 mm or less, more preferably 1. It is 0.0 mm or less, more preferably 0.80 mm or less. The discharge hole diameter of the discharge hole 27a is preferably 0.010 mm or more and 5.0 mm or less, more preferably 0.10 mm or more and 1.0 mm or less, and further preferably 0.15 mm or more and 0.80 mm or less. The discharge hole diameter of the discharge hole 27a is preferably circular, but may be non-circular, and the discharge hole diameter of the discharge hole 27a in that case is a hydraulic power equivalent diameter (= 4 × (cross-sectional area) / ( Edge length)).

(Manufacturing method of hydrogel fiber)
In the method for producing a hydrogel fiber according to the embodiment, first, a first aqueous solution containing metal ions and a second aqueous solution containing a gel-forming substance that forms an ion-crosslinked hydrogel by ion exchange with the metal ions are prepared. , The first aqueous solution is charged into the fiber recovery tank 10 of the hydrogel fiber manufacturing system S, and the second aqueous solution is charged into the second aqueous solution storage tank 21 of the second aqueous solution supply unit 20. At this time, the fiber recovery tank 10 is charged with the first aqueous solution to the extent that the discharge nozzle 27 is immersed. Next, the cock 23 interposed in the second aqueous solution supply pipe 22 is opened and the pump 24 is operated to circulate the second aqueous solution through the second aqueous solution supply pipe 22. As a result, in the fiber recovery tank 10, the second aqueous solution is linearly discharged into the first aqueous solution from the discharge hole 27a of the discharge nozzle 27 in a state where the Reynolds number is 10 or less. Then, a hydrogel fiber is manufactured by forming an ion-crosslinked hydrogel by ion exchange between the first aqueous solution and the second aqueous solution. Then, in the method for producing a hydrogel fiber according to the embodiment, at this time, the pressure loss ΔP when the second aqueous solution is discharged into the first aqueous solution by the second aqueous solution supply unit 20 is set in the range of 0.20 MPa or more. ..

The present inventors can stably produce a hydrogel fiber when the second aqueous solution is linearly discharged into the first aqueous solution in a state where the Reynolds number is 10 or less, and the obtained hydrogel fiber can be produced. It was found that the fiber diameter of the above has a correlation with the pressure loss ΔP in the range where the pressure loss ΔP at that time is 0.20 MPa or more. It is presumed that this is because the velocity distribution in the cross section of the flowing second aqueous solution has a correlation with the fiber diameter of the hydrogel fiber obtained, and the velocity distribution has a correlation with the pressure loss ΔP. .. From this, according to the method for producing a hydrogel fiber according to the embodiment, the fiber diameter of the hydrogel fiber obtained by setting the pressure loss ΔP can be controlled, and therefore, the second aqueous solution supply unit 20 can control the first. If the pressure loss ΔP when discharging the second aqueous solution into the aqueous solution is set to a value corresponding to the target fiber diameter in the range of 0.20 MPa or more, the hydrogel fiber having a desired fiber diameter can be formed along the length direction. It can be manufactured by suppressing fluctuations in the fiber diameter. Here, the “pressure loss” in the present application means a pressure loss in the discharge means which is a terminal member of the pipe. Therefore, in the method for manufacturing a hydrogel fiber according to the embodiment, the pressure loss ΔP is the pressure loss ΔP at the discharge nozzle 27. This pressure loss ΔP can be calculated from the difference between the indicated value of the pressure gauge 26 when the discharge nozzle 27 is attached and operated and the indicated value of the pressure gauge 26 when the discharge nozzle 27 is removed and operated.

Examples of the metal ion contained in the first aqueous solution include potassium ion and the like as the monovalent metal ion, and calcium ion, magnesium ion, iron ion (II) and copper ion (II) as the polyvalent metal ion. ), Divalent metal ions such as zinc ion and manganese ion; and trivalent metal ions such as aluminum ion and iron ion (III). The first aqueous solution preferably contains one or more of these metal ions. Potassium ion is preferable as the monovalent metal ion, and calcium ion and magnesium ion are preferable as the polyvalent metal ion.

The first aqueous solution is preferably an aqueous solution containing a metal salt containing metal ions. Metal salts containing metal ions include inorganic acid salts such as chloride salts, sulfates, nitrates, carbonates and phosphates; monovalent metal salts of organic acid salts such as lactates, citrates and acetates. And polyvalent metal salts. The first aqueous solution preferably contains one or more of these metal salts. Chloride salts are preferable as the inorganic acid salts.

_{The concentration c 1} of the metal salt in the first aqueous solution is preferably 0.30% by mass or more, more preferably 0.50% by mass or more, still more preferably 1.0% by mass or more, from the viewpoint of accurately controlling the fiber diameter. From the same viewpoint, it is preferably 30% by mass or less, more preferably 20% by mass or less, and further preferably 10% by mass or less. The concentration c ₁ of this metal salt is preferably 0.30% by mass or more and 30% by mass or less, more preferably 0.50% by mass or more and 20% by mass or less, and further preferably 1.0% by mass or more and 10% by mass or less. is there.

The first aqueous solution may contain a surfactant, an organic solvent, a preservative and the like as long as the action and effect of controlling the fiber diameter are not impaired.

_{The viscosity η 1} of the first aqueous solution may be adjusted by appropriately adding a viscosity regulator or the like, if necessary. _{The viscosity η 1} of the first aqueous solution is preferably 0.10 mPa · s or more, more preferably 0.50 mPa · s or more, still more preferably 1.0 mPa · s or more, from the viewpoint of accurately controlling the fiber diameter. From the same viewpoint, it is preferably 10000 mPa · s or less, more preferably 5000 mPa · s or less, and further preferably 3000 mPa · s or less. _{The viscosity η 1} of the first aqueous solution is preferably 0.10 mPa · s or more and 10,000 mPa · s or less, more preferably 0.50 mPa · s or more and 5000 mPa · s or less, and further preferably 1.0 mPa · s or more and 3000 mPa · s or less. Is. Here, the viscosity eta ₂ of the second aqueous solution viscosity eta ₁ and below the first aqueous solution is measured by the viscosity measuring instrument such as a B-type viscometer.

Examples of the gel-forming substance contained in the second aqueous solution include alginates such as sodium alginate, potassium alginate, and ammonium alginate; κ-carrageenan, ι-carrageenan, and LM pectin. The second aqueous solution preferably contains one or more of these gel-forming substances. As the gel-forming substance contained in the second aqueous solution, sodium alginate and κ-carrageenan are preferable. Alginate is formed by calcium ions and the like, κ-carrageenan is formed by potassium ions, ι-carrageenan is formed by calcium ions, and LM pectin is formed by calcium ions and the like.

_{The concentration c 2} of the gel-forming substance in the second aqueous solution is preferably 0.50% by mass or more, more preferably 0.70% by mass or more, still more preferably 1.0% by mass, from the viewpoint of accurately controlling the fiber diameter. From the same viewpoint, it is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and further preferably 3.0% by mass or less. _{The concentration c 2} of this gel-forming substance is preferably 0.50% by mass or more and 5.0% by mass or less, more preferably 0.70% by mass or more and 4.0% by mass or less, and further preferably 1.0% by mass or more. It is 3.0% by mass or less.

The second aqueous solution may contain an aqueous and / or oily functional substance, a surfactant, an organic solvent, a reactive substance and the like as long as the action and effect of controlling the fiber diameter are not impaired.

Viscosity eta ₂ of the second aqueous solution can be adjusted concentration c ₂ in the gel-forming _material, molecular weight, and by the operating temperature. _{The viscosity η 2} of the second aqueous solution is preferably 10 mPa · s or more, more preferably 50 mPa · s or more, still more preferably 100 mPa · s or more, from the viewpoint of accurately controlling the fiber diameter, and from the same viewpoint. It is preferably 100,000 mPa · s or less, more preferably 50,000 mPa · s or less, and further preferably 30,000 mPa · s or less. _{The viscosity η 2} of the second aqueous solution is preferably 10 mPa · s or more and 100,000 mPa · s or less, more preferably 50 mPa · s or more and 50,000 mPa · s or less, and further preferably 100 mPa · s or more and 30,000 mPa · s or less.

The second aqueous solution is circulated through the discharge nozzle 27 under laminar flow conditions. The Reynolds number Re ₂ is 10 or less, and is preferably 8.0 or less from the viewpoint of accurately controlling the fiber diameter and suppressing fluctuations in the fiber diameter along the length direction to produce a hydrogel fiber. More preferably, it is 7.0 or less.

_{The flow velocity u 2} of the second aqueous solution flowing through the discharge nozzle 27 is preferably 0.10 m / sec or more, more preferably 0.30 m / sec or more, still more preferably 0.50 m, from the viewpoint of accurately controlling the fiber diameter. It is more than / sec, and from the same viewpoint, it is preferably 20 m / sec or less, more preferably 15 m / sec or less, still more preferably 10 m / sec or less. The flow velocity u ₂ of the second aqueous solution is preferably 0.10 m / sec or more and 20 m / sec or less, more preferably 0.30 m / sec or more and 15 m / sec or less, and further preferably 0.50 m / sec or more and 10 m / sec or less. Is.

Flow rate _{Q 2} of the second aqueous solution flowing through the second aqueous solution supply unit 20, from the viewpoint of controlling precisely the fiber diameter, preferably 0.10 mL / min or more, more preferably 0.50 mL / min or more, more preferably It is 1.0 mL / min or more, and from the same viewpoint, it is preferably 10000 mL / min or less, more preferably 1000 mL / min or less, still more preferably 100 mL / min or less. Flow rate _{Q 2} of the second aqueous solution is preferably 0.10 mL / min to 10000 mL / min or less, more preferably 0.50 mL / min or more 1000 mL / min or less, more preferably 1.0 mL / min to 100 mL / min or less Is.

The pressure loss ΔP when the second aqueous solution is discharged into the first aqueous solution by the second aqueous solution supply unit 20 is 0.20 MPa or more, but from the viewpoint of accurately controlling the fiber diameter, it is preferably 0.23 MPa or more. It is preferably 0.25 MPa or more, more preferably 0.30 MPa or more, and from the same viewpoint, preferably 1.0 MPa or less, more preferably 0.90 MPa or less, still more preferably 0.80 MPa or less. The pressure loss ΔP is preferably 0.23 MPa or more and 1.0 MPa or less, more preferably 0.25 MPa or more and 0.90 MPa or less, and further preferably 0.30 MPa or more and 0.80 MPa or less. The pressure loss ΔP in the second aqueous solution supply unit 20 can be controlled by the flow rate Q ₂ of the apparatus configuration and the second aqueous solution, such as the discharge nozzle 27.

_{The concentration c 1} of the metal salt in the first aqueous solution may be the same as the concentration c ₂ of the gel-forming substance in the second aqueous solution, or may be lower than _{the concentration c 2 of the gel-forming substance in the second aqueous solution.} Alternatively, it may be higher than _{the concentration c 2} of the gel-forming substance in the second aqueous solution. The ratio to the concentration _{c 2} in the gel-forming material in a second aqueous solution having a concentration _{c 1} of the metal salt in the first aqueous solution _(c 1 / _{c 2),} from the viewpoint of controlling precisely the fiber diameter, preferably 0.050 or more, It is more preferably 0.10 or more, still more preferably 0.30 or more, and from the same viewpoint, it is preferably 60 or less, more preferably 40 or less, still more preferably 20 or less. This concentration ratio (c ₁ / c ₂ ) is preferably 0.050 or more and 60 or less, more preferably 0.10 or more and 40 or less, and further preferably 0.30 or more and 20 or less.

_{The viscosity η 1} of the first aqueous solution is preferably lower than _{the viscosity η 2} of the second aqueous solution. The ratio viscosity eta ₁ of the first aqueous solution viscosity eta ₂ of the second aqueous solution (η _{2 /} η _1), from the viewpoint of controlling precisely the fiber diameter, preferably 1.0 or more, more preferably 5.0 or more It is more preferably 10 or more, and from the same viewpoint, it is preferably 100,000 or less, more preferably 50,000 or less, still more preferably 30,000 or less. This viscosity ratio (η ₂ / η ₁ ) is preferably 1.0 or more and 100,000 or less, more preferably 5.0 or more and 50,000 or less, and further preferably 10 or more and 30,000 or less.

The temperature of the first aqueous solution is preferably the same as the temperature of the second aqueous solution, but may be different.

The fiber diameter of the hydrogel fiber recovered in the fiber recovery tank 10 is preferably 1.0 μm or more, more preferably 5.0 μm or more, further preferably 10 μm or more, and preferably 1000 μm or less, more preferably 800 μm. Below, it is more preferably 700 μm or less. The fiber diameter of the hydrogel fiber is preferably 1.0 μm or more and 1000 μm or less, more preferably 5.0 μm or more and 800 μm or less, and further preferably 10 μm or more and 700 μm or less. Here, the "fiber diameter of the hydrogel fiber" in the present application refers to the atmospheric pressure after drying the wet hydrogel fiber in an atmosphere of atmospheric pressure, temperature 25 ° C., and humidity 50% RH for 24 hours. It is a fiber diameter in a state of being stored in an atmosphere of a temperature of 25 ° C. and a humidity of 50% RH. Further, the "fiber diameter" in the present application is obtained as an average value of 10 points along the length direction in an arbitrary length of 3 cm from an optical microscope observation image of the hydrogel fiber.

The fiber diameter of the hydrogel fiber is preferably smaller than the discharge hole diameter of the discharge nozzle 27. The fiber diameter of the hydrogel fiber is preferably 0.0050 times or more, more preferably 0.020 times or more, still more preferably 0.050 times or more, and preferably 0.050 times or more, with respect to the discharge hole diameter of the discharge nozzle 27. It is 0.90 times or less, more preferably 0.80 times or less, still more preferably 0.70 times or less. The fiber diameter of the hydrogel fiber is preferably 0.0050 times or more and 0.90 times or less, more preferably 0.020 times or more and 0.80 times or less, still more preferably 0. It is 050 times or more and 0.70 times or less.

For the fluctuation of the fiber diameter of the hydrogel fiber, select five parts having an arbitrary section length L from the obtained optical microscope observation image of the hydrogel fiber, and the difference between the maximum fiber diameter D and the minimum fiber diameter d in each part. It is possible to calculate (Dd) / L by dividing (Dd) by the section length L, and use the value obtained by averaging the (Dd) / L of the five points calculated in this way as an index. it can. The average value of (Dd) / L is preferably 0.080 or less, more preferably 0.070 or less, and further preferably 0.060 or less.

The recovered hydrogel fiber is used as a compounding material for, for example, cosmetics, pharmaceuticals, quasi-drugs, foods and the like.

(Manufacturing of hydrogel fiber)
Hydrogel fibers were prepared as in Examples 1 to 12 and Comparative Example 1 below, using an aqueous solution of calcium chloride as a first aqueous solution and an aqueous solution of sodium alginate as a second aqueous solution. Then, the formed wet hydrogel fiber is taken out from the recovery tank 10, dried for 24 hours in an atmosphere of atmospheric pressure, temperature 25 ° C., and humidity 50% RH, and then atmospheric pressure, temperature 25 ° C. , And stored in an atmosphere of 50% humidity RH, and observed with an optical microscope to determine the fiber diameter. Specifically, the fiber diameter was determined from the obtained optical microscope observation image of the hydrogel fiber as an average value of 10 points along the length direction in an arbitrary portion having a length of 3 cm. In addition, the presence or absence of fluctuations in the fiber diameter along the length direction of the obtained hydrogel fiber was evaluated. Specifically, the presence or absence of fluctuations in the fiber diameter is determined by selecting five parts having an arbitrary section length L (200 μm) from the obtained optical microscope observation image of the hydrogel fiber, and the maximum fiber diameter D and the minimum in each part. The difference (Dd) from the fiber diameter d is divided by the section length L to calculate (Dd) / L, and the average value of (Dd) / L at five locations is calculated, and the average value is 0. When it was .080 or less, it was evaluated as "no fluctuation", and when it was larger than 0.080, it was evaluated as "with fluctuation". The contents of Examples 1 to 12 and Comparative Example 1 are also shown in Tables 1 and 2.

<Example 1>
693 g of ion-exchanged water is charged in a 1 L glass beaker, and 7 g of calcium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) is added thereto and dissolved at room temperature to prepare a calcium _{chloride aqueous solution having a concentration c 1} of 1.0% by mass. It was prepared as a first aqueous solution (viscosity η ₁ : 1.0 mPa · s, specific gravity: 1.013). Further, 693 g of ion-exchanged water was charged into another 1 L glass beaker, 7 g of sodium alginate (manufactured by Wako Pure Chemical Industries, Ltd.) was added thereto, and the mixture was heated to 70 ° C. to dissolve it, and the concentration c ₂ was 1. A 0 mass% sodium alginate aqueous solution _{was prepared as a second aqueous solution (viscosity η 2} : 290 mPa · s, specific gravity: 1.004).

In Example 1, a hydrogel fiber manufacturing system S having the same configuration as that shown in FIG. 1 was used. The discharge nozzle 27 is composed of a SUS pipe (static contact angle: 63 °) having an outer diameter of 1.6 mm and an inner diameter (discharge hole diameter) of 0.25 mm, and the pump 24 is a gear pump (model: DGS.11EEV2NN15000 Tuthill). ) Was used.

The fiber recovery tank 10 composed of a 3 L beaker was charged with the first aqueous solution whose temperature was adjusted to 25 ° C., and the second aqueous solution storage tank 21 was charged with the second aqueous solution whose temperature was adjusted to 25 ° C.

The second solution, laminar flow in which the flow rate _{Q 2} and 6.0 mL / min (Reynolds number _Re 2: 1.7) at was discharged into the first aqueous solution. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 2000 mm / sec, and the pressure loss ΔP was 0.40 MPa.

When the second aqueous solution was continuously discharged into the first aqueous solution, the second aqueous solution immediately gelled to form a hydrogel fiber.

The fiber diameter of the obtained hydrogel fiber was 150 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 2>
In Example 2, the flow rate _{Q 2} of the second aqueous solution 9.0 mL / min (Reynolds number _Re 2: 2.7) except for using, was subjected to the same procedure as in Example 1. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 3100 mm / sec, and the pressure loss ΔP was 0.50 MPa.

The fiber diameter of the obtained hydrogel fiber was 80 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 3>
In Example 3, the flow rate _{Q 2} of the second aqueous solution 12 mL / min (Reynolds number _Re 2: 3.5) except for using, was subjected to the same procedure as in Example 1. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 4100 mm / sec, and the pressure loss ΔP was 0.60 MPa.

The fiber diameter of the obtained hydrogel fiber was 60 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 4>
In Example 4, the flow rate _{Q 2} of the second aqueous solution 18 mL / min (Reynolds number _Re 2: 5.3) except for using, was subjected to the same procedure as in Example 1. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 6100 mm / sec, and the pressure loss ΔP was 0.75 MPa.

The fiber diameter of the obtained hydrogel fiber was 40 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 5>
In Example 5, the discharge nozzle 27 was composed of a SUS pipe having an outer diameter of 1.6 mm and an inner diameter (discharge hole diameter) of 0.50 mm. Then, the flow rate _{Q 2} of the second aqueous solution 25 mL / min (Reynolds number _Re 2: 3.6) except for using, was subjected to the same procedure as in Example 1. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 2100 mm / sec, and the pressure loss ΔP was 0.23 MPa.

The fiber diameter of the obtained hydrogel fiber was 250 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 6>
In Example 6, the flow rate _{Q 2} of the second aqueous solution 45 mL / min (Reynolds number _Re 2: 6.6) except for using, was subjected to the same procedure as in Example 5. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 3800 mm / sec, and the pressure loss ΔP was 0.33 MPa.

The fiber diameter of the obtained hydrogel fiber was 180 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Comparative example 1>
In Comparative Example 1, the flow rate _{Q 2} of the second aqueous solution 100 mL / min (Reynolds number _Re 2: 15) except for using, was subjected to the same procedure as in Example 5. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 8500 mm / sec, and the pressure loss ΔP was 0.64 MPa.

Fluctuations along the length direction were confirmed in the fiber diameter of the obtained hydrogel fiber, and the average fiber diameter was 50 μm.

<Example 7>
In Example 7, the discharge nozzle 27 was composed of a PTFE pipe (static contact angle: 101 °) having an outer diameter of 1.6 mm and an inner diameter (discharge hole diameter) of 0.25 mm. Then, the flow rate _{Q 2} of the second aqueous solution 6 mL / min (Reynolds number _Re 2: 1.7) except for using, was subjected to the same procedure as in Example 1. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 2000 mm / sec, and the pressure loss ΔP was 0.45 MPa.

The fiber diameter of the obtained hydrogel fiber was 60 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 8>
In Example 8, the flow rate _{Q 2} of the second aqueous solution 9 mL / min (Reynolds number _Re 2: 2.6) except for using, was subjected to the same procedure as in Example 7. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 3100 mm / sec, and the pressure loss ΔP was 0.55 MPa.

The fiber diameter of the obtained hydrogel fiber was 30 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 9>
In Example 9, the flow rate _{Q 2} of the second aqueous solution 12 mL / min (Reynolds number _Re 2: 3.5) except for using, was subjected to the same procedure as in Example 7. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 4100 mm / sec, and the pressure loss ΔP was 0.68 MPa.

The fiber diameter of the obtained hydrogel fiber was 25 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 10>
In Example 10, the flow rate _{Q 2} of the second aqueous solution 18 mL / min (Reynolds number _Re 2: 5.2) except for using, was subjected to the same procedure as in Example 7. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 6100 mm / sec, and the pressure loss ΔP was 0.88 MPa.

The fiber diameter of the obtained hydrogel fiber was 20 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 11>
In Example 11, the discharge nozzle 27 was composed of a PTFE pipe having an outer diameter of 1.6 mm and an inner diameter (discharge hole diameter) of 0.17 mm. Then, the flow rate _{Q 2} of the second aqueous solution 5 mL / min (Reynolds number _Re 2: 2.1) except for using, was subjected to the same procedure as in Example 1. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 3700 mm / sec, and the pressure loss ΔP was 0.45 MPa.

The fiber diameter of the obtained hydrogel fiber was 70 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

<Example 12>
In Example 12, the flow rate _{Q 2} of the second aqueous solution 18 mL / min (Reynolds number _Re 2: 6.8) except for using, was subjected to the same procedure as in Example 11. _{The flow velocity u 2} of the second aqueous solution at the discharge nozzle 27 was 11700 mm / sec, and the pressure loss ΔP was 0.95 MPa.

The fiber diameter of the obtained hydrogel fiber was 18 μm, and no fluctuation of the fiber diameter along the length direction was confirmed.

(Results and discussion)
FIG. 3 shows the relationship between the pressure loss ΔP for Examples 1 to 12 and Comparative Example 1 and the fiber diameter of the obtained hydrogel fiber.

According to FIG. 3, the material of the discharge nozzle 27 is compared in Examples 1 to 6 and Comparative Example 1 is SUS, configuration of the discharge nozzle 27 used during the production of the hydrogel fiber, the flow rate Q ₂ and a second aqueous solution It can be seen that the fiber diameter of the obtained hydrogel fiber has a correlation with the pressure loss ΔP regardless of the flow velocity u ₂ and the Reynolds number Re _{2 of the second aqueous solution. However, in Comparative Example 1 in which the Reynolds number Re 2} of the second aqueous solution was 15 and was larger than 10, fluctuation of the fiber diameter along the length direction was confirmed. Further, the correlation with the pressure loss ΔP of the fiber diameter of the hydrogel fiber is also recognized in the comparison of Examples 7 to 12 in which the material of the discharge nozzle 27 is PTFE.

Comparing Examples 1 to 6 in which the material of the discharge nozzle 27 is SUS and Examples 7 to 12 in which the material is PTFE, the latter can obtain a hydrogel fiber having a smaller fiber diameter than the former. I understand.

The present invention is useful in the technical field of a method for manufacturing a hydrogel fiber and a method for controlling the fiber diameter thereof.

S Hydrogel fiber manufacturing system 10 Fiber recovery tank 20 Second aqueous solution supply unit 21 Second aqueous solution storage tank 22 Second aqueous solution supply pipe 23 Cock 24 Pump 25 Flow meter 26 Pressure gauge 27 Discharge nozzle (discharge means)
27a Discharge hole 27b Flow path inner wall 27c Peripheral part

Claims (6)

Hydrogel by linearly discharging a second aqueous solution containing a gel-forming substance that forms an ion-crosslinked hydrogel by ion exchange with the metal ions into a first aqueous solution containing metal ions using a discharge means. A method of manufacturing fibers
A method for producing a hydrogel fiber, in which the second aqueous solution is discharged into the first aqueous solution by the discharging means in a state where the Reynolds number is 10 or less, and the pressure loss at that time is set in the range of 0.20 MPa or more. The method for manufacturing a hydrogel fiber according to claim 1, wherein the static contact angle of the material forming the portion formed by at least the discharge hole of the discharge means with respect to water is 40 ° or more. The method for manufacturing a hydrogel fiber according to claim 1 or 2, wherein the discharge hole diameter of the discharge means is 0.010 mm or more and 5.0 mm or less. The method for producing a hydrogel fiber according to any one of claims 1 to 3, wherein the hydrogel fiber has a fiber diameter of 1000 μm or less. The method for producing a hydrogel fiber according to any one of claims 1 to 4, wherein the gel-forming substance is alginate. It is produced by linearly discharging a second aqueous solution containing a gel-forming substance that forms an ion-crosslinked hydrogel by ion exchange with the metal ions into a first aqueous solution containing metal ions using a discharge means. A method of controlling the fiber diameter of a hydrogel fiber.
The second aqueous solution is discharged into the first aqueous solution by the discharging means in a state where the Reynolds number is 10 or less, and the pressure loss at that time having a correlation with the fiber diameter is targeted in the range of 0.20 MPa or more. A method for controlling the fiber diameter of a hydrogel fiber, which is set to a value corresponding to the fiber diameter.

Images