JP2019189958A - Sea island fiber and method for producing the same - Google Patents

Abstract

To suppress the detachment of the coating on the fiber.SOLUTION: The sea-island fiber of the present invention has a sea-island structure in which the fiber diameter D is 100 μm or more and 1000 μm or less, and which includes a sea component and an island component. In the cross section perpendicular to the fiber longitudinal direction, the area ratio of the island component in the circle with a diameter of 2/3D from the center of the cross section is 10% or more and 50% or less with respect to the area of the circle with a diameter of 2/3D.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a functional sea island fiber, in particular, an absorptive fiber suitable for removing harmful substances in water, a water purification filter using the sea island fiber, and a water treatment method using the water purification filter.

  Fibers include natural fibers such as cotton and linen, chemical fibers such as rayon, and synthetic fibers such as polyester and nylon, and are widely used for clothing and industrial applications by taking advantage of their elongated shape. On the other hand, in recent years, fibers having various chemical properties have been studied on the surface thereof, for example, hygroscopic functions (for example, Patent Document 1) that can impart wearing comfort during extreme heat or exercise in clothing applications, Examples thereof include a heat retention function that can provide comfort in extreme cold (for example, Patent Document 2). Further, in industrial applications, an adsorption function (for example, Patent Document 3) given to a filter that removes a specific substance from a mixed fluid can be mentioned.

  As a technique for imparting these functions to fibers, the above-mentioned Patent Document 1 describes two steps of 120 ° C. and 180 ° C. after drawing polyester fibers by mixing fine particles of polyacrylic acid with a silicon-based binder. A fiber that has been dry-heated is disclosed. Another method is to graft a monomer having a function to the polymer chain of the fiber, and the above-mentioned Patent Document 3 discloses ionizing radiation to a core-sheath fiber using a polymer as a graft base as a sheath component. A method for producing a separation functional fiber is disclosed in which glycidyl methacrylate is grafted to the fiber after irradiation.

JP 2003-147680 A JP 2006-45720 A Japanese Patent Application Laid-Open No. 08-199480

  Since the conventional technique has a problem of incorporating moisture components generated from the human body and trace components in the fluid into the fiber surface, a compound having a function exists in a thin thickness on the surface of the fiber. There is no particular consideration for capacity. On the other hand, there is a problem that even if a large amount of a substance having a function is attached to the fiber, the substance is peeled off or dropped off by itself.

  An object of this invention is to provide the technique which can suppress peeling of the substance around a core material in the fiber containing a core material and the substance adhering to the core material.

  In order to achieve the above object, the sea-island fiber of the present invention has a fiber diameter D of 100 μm or more and 1000 μm or less, has a sea-island structure including a sea component and an island component, and has a cross-section perpendicular to the longitudinal direction of the fiber from the center of the cross-section. The area ratio of the island components in the 2 / 3D diameter circle is 10% or more and 50% or less with respect to the area of the 2 / 3D diameter circle.

  In the sea-island fiber of the present invention, the ratio of the island component in the vicinity of the center is in the above-mentioned range, which is between the surface of the island-island fiber and the island component due to the sea component present in the gap between the island components. The sea component is firmly fixed to the island component. Therefore, the peeling and dropping of sea components are suppressed.

FIG. 1 is a SEM cross-sectional photograph of an example of the sea-island fiber of the present invention. 2 is a schematic view illustrating the sea-island fiber of the present invention obtained in Example 1. FIG. FIG. 3 is a schematic view illustrating the sea-island fiber of the present invention obtained in Example 4. FIG. 4 is a schematic view illustrating sea-island fibers obtained in Comparative Example 4. FIG. 5 is a schematic view illustrating sea-island fibers obtained in Comparative Example 5. FIG. 6 is a schematic view illustrating sea-island fibers obtained in Comparative Example 6. FIG. 7 is a schematic view illustrating sea-island fibers obtained in Comparative Example 7. FIG. 8 is a schematic view illustrating the fiber coating method of the present invention. FIG. 9 is a schematic view illustrating the fiber coating method of the present invention.

  The sea-island fiber of the present invention is a sea-island fiber in which the area ratio of the island component in a circle having a diameter of 2 / 3D from the center of the cross section is 10% or more and 50% or less with respect to all components in a cross section perpendicular to the fiber direction It is characterized by. A fiber provided with a high ratio of a substance having a function of hygroscopicity, adsorptivity and the like to a sea component can be provided, which is a sea-island fiber that is difficult to peel off by rubbing or the like.

1-1. Shape of sea-island fiber The sea-island fiber of the present invention has a sea-island structure including a sea component and an island component. The sea component and the island component are regions having different compositions in a cross section (radial cross section) perpendicular to the long axis of the fiber. In the sea-island structure, a plurality of island components are scattered in the sea component.

  For example, by using a specific substance (hereinafter referred to as “functional substance”) having functions such as hygroscopicity and adsorptivity to sea components, and using soft and high-strength chemical fibers for island components, Fiber can be provided. As a conventional functional fiber, a core-sheath fiber having a hygroscopic and adsorptive component as shown in FIGS. 6 and 7 as a sheath component is known. In the present invention, it was found that this problem can be solved by using sea-island fibers as shown in FIGS. It seems that peeling is suppressed by the functional component which is a sea component entering between the core fibers which are island components and the sea component being connected.

  In the cross section perpendicular to the major axis direction of the fiber, the area occupied by the island component is preferably 10% or more and 50% or less in a circle having a diameter of 2 / 3D from the center of the cross section. As described above, since many sea components (that is, functional substances) enter the gaps between the island components, the sea components are difficult to peel off, and the proportion of the functional substances in the fibers increases. As described above, the sea-island fiber has the effect of preventing the sea component polymer from being peeled off and detached, but the area ratio of the island component in the circle with a diameter of 2 / 3D from the center of the cross section is 10% to 50%. By being, it can fully acquire the effect of peeling prevention. Moreover, since this area ratio is 15% or more and 40% or less, and further 17% or more and 25% or less, the effect of suppressing peeling is further enhanced, which is more preferable.

  In the fiber obtained by coating the core fiber by the conventional dip nip method, the core fiber is densely packed by the nip process, so that the island component cannot be scattered as shown in FIG. 4 or FIG. The method for producing the sea-island fiber of the present invention will be described later.

  In the sea-island fiber of the present invention, all island components may be covered with sea components as shown in FIG. 2, and the island components covered with sea components as shown in FIG. 3 and the outer peripheral side are exposed. You may be comprised with an island component. However, when a compound having a function as a sea component is used, it is preferable that all island components are covered with the sea component as shown in FIG. 2 because the retention rate of the functional sea component is increased. .

  In the sea-island fiber, the ratio represented by (mass of sea component) / (mass of island component) is preferably 30% by mass or more, more preferably 100% by mass or more, and 300% by mass or more. More preferably. When the ratio is 30% by mass or more, the retention rate of the sea component is high. For example, when a compound having an adsorption function for a specific substance is used as the sea component, a high adsorption capacity can be achieved. On the other hand, the ratio is preferably 1000% by mass or less, and more preferably 700% by mass or less. When it is 1000% by mass or less, it has high flexibility and strength, and is easy to handle.

  In the sea-island fiber of the present invention, the lower limit of the diameter D of the sea-island fiber needs to be 100 μm or more, preferably 200 μm or more, and more preferably 300 μm or more. Sufficient strength can be obtained by being 50 micrometers or more. As an upper limit, it is necessary to be 1000 micrometers or less, it is preferable that it is 800 micrometers or less, and it is more preferable that it is 500 micrometers or less. By being 3000 μm or less, an effect as a fiber can be obtained.

1-2. Sea component The sea component is a structure containing a functional substance having functions such as adsorptivity, hygroscopicity, exothermicity, and molecular sieving. Since the sea component plays a role and the island component takes the strength, both functionality and strength can be achieved.

  The “functional substance” may include not only a compound having a function but also a mixture of a compound having a function and a compound having no function.

  The “structure” may be either porous or non-porous, and the porous may be a co-continuous structure of a solid and a void or an aggregate of particles. The structure may have a porous or non-porous base material and particles dispersed therein. It is also preferable that the constituent sea component is a porous material having molecular sieving properties.

  The content of the functional compound in the sea component is preferably 40% by mass or more.

  Among the functional compounds, examples of the resin include a resin having a cationic functional group such as a carboxy group or a sulfonyl group, an anionic functional group such as an amino group, or a hydroxyl group in the side chain. These resins are preferably cross-linked to the extent that they do not dissolve in water or the like.

  The resin having a carboxy group is a polymer compound having a plurality of carboxy groups in the molecule, and examples thereof include a polymer of acrylic acid or methacrylic acid, or a copolymer containing these. Examples of the copolymer include a copolymer containing at least one of acrylic acid and methacrylic acid as a monomer component, a copolymer containing maleic anhydride as a monomer component, acrylic acid ester, and methacrylic acid ester. More specifically, examples of the polymer compound having a carboxy group include polyacrylic acid and polymethacrylic acid.

  Examples of the functional particles include metal oxides and hydrates thereof. Among them, in particular, rare earth element hydroxides and rare earth element hydroxides can be mentioned because they can adsorb boron, arsenic, phosphorus, and fluorine ions. As rare earth elements, scandium Sc of atomic number 21 and yttrium Y of 39 according to the periodic table of elements, lanthanoid elements of 57 to 71, ie, lanthanum La, cerium Ce, praseodymium Pr, neodymium Nd, promethium Pm, samarium Sm, europium Eu, Cadolinium Gd, terbium Tb, dysprosium Dy, holmium Ho, erbium Er, thulium Tm, ytterbium Yb, lutetium Lu are applicable, and among these, cerium is a preferable element from the viewpoint of the ion removal performance. Valent cerium is preferred. Mixtures of these hydroxides and / or hydrous oxides are also useful. The higher the content of the adsorbent particles, the higher the adsorption performance. Therefore, the adsorbent particle mass ratio r in the total mass of the adsorbent particles and the polymer resin is preferably 30% by mass or more, and 50% by mass or more. More preferably. On the other hand, if it is too high, the strength of the polymer resin is lowered, causing deformation and breakage. Therefore, the upper limit is preferably 99% by mass or less, and more preferably 97% by mass or less.

The content rate of the particles can be measured by the following procedure. First, the mass (W ₁ ) of the fibrous adsorbent is weighed. Next, the resin composition is peeled from the fibrous adsorbent, and the mass (W ₂ ) of the resin composition is weighed. Next, the polymer resin is dissolved in a good solvent such as a strong alkaline aqueous solution or combined with a method of heating at 800 ° C. or higher with an electric furnace to take out the adsorbent particles, and the mass (W ₃ ) of the adsorbent particles is weighed. . The adsorptive particle mass ratio r is the ratio of W ₃ and W ₂ , that is, the percentage of r = W ₃ / W ₂ .

  As a method for confirming whether or not the polymer resin has been removed from the fibrous adsorbent, it can be confirmed by observing the surface and the cross section of the fibrous adsorbent using a microscope or a scanning electron microscope (SEM). .

  The water content of the particles is preferably 1% by mass or more, and more preferably 5% by mass or more. When the content is 1% by mass or more, an adsorption site can be imparted to the inside of the particle, and the adsorption capacity is sufficient. Moreover, it is preferable that it is 30 mass% or less, and it is more preferable that it is 20 mass% or less. By being 30% by mass or less, the density of the adsorption sites inside the particles can be increased, and the adsorption capacity is sufficient.

  These fine particles preferably have a particle size of 50 μm or less, and more preferably 10 μm or less. When the particle diameter is 50 μm or less, the number of adsorption sites existing on the outer surface of the particle can be increased, and the adsorption capacity is sufficient. Moreover, it is preferable that it is 0.01 micrometer or more, and it is more preferable that it is 0.05 micrometer or more. By being 0.01 μm or more, the particles are less likely to aggregate in the solution at the time of producing the fibrous adsorbent, and the particles can be uniformly coated on the fibers.

1-3. Island component In the sea-island fiber of the present invention, the island component is a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate or polycarbonate, an aliphatic polyamide, an aromatic polyamide, acrylic, polyacrylonitrile, polyvinyl chloride, PTFE, or polyvinylidene fluoride. Synthetic resins such as halogenated polyolefins and the like, and resins made from natural fibers such as wool, silk, and cotton can be used. Among these, polyamide and polyester are particularly preferable, and nylon 6 and nylon 6,6 are particularly preferable for polyamide, and polyethylene terephthalate (PET) is particularly preferable for polyester because of its low cost and high strength.

  The number of island components is not particularly limited, but is preferably 4 or more, more preferably 12 or more, and still more preferably 36 or more. When the number of island components is four or more, the strength is increased, and the retention rate of a resin that becomes a sea component at the time of manufacturing, which will be described later, can be increased to obtain a fiber having a higher function. On the other hand, in order to increase the ratio of the sea component to the island component, the island component is preferably 108 or less, and more preferably 72 or less.

The cross-sectional shape of the island component is not limited to a circular shape, but is the same as 3-8 convex portions called a multi-lobe cross section such as a polygonal cross section, a flat cross section, a lens mold cross section, a trilobe cross section, and a six lobe cross section. It may be a modified cross section having a concave portion, a hollow cross section or other known modified cross section. The irregularity of the multi-global cross section is preferably 1.2 or more and 6.0 or less. The irregularity referred to here is obtained by dividing the circumscribed circle diameter of the cross-sectional shape by the inscribed circle diameter of the cross-sectional shape. When the irregularity is 1.2 or more, irregularities in the irregular cross section are large, so that the contact area between the island component and the sea component is large, and peeling is suppressed. On the other hand, if the degree of deformity is 6.0 or less, the strength increases.
The fiber diameter d of one filament in the core fiber is preferably 1 μm or more, and more preferably 10 μm or more. When the fiber diameter d is 1 μm or more, the strength of the sea-island fiber is increased. The upper limit of the fiber diameter d is preferably 50 μm or less, and more preferably 30 μm or less. When the upper limit of the fiber diameter d is 50 μm or less, peeling of the resin and the core fiber is suppressed.

2. Production method The preferred production process of the present invention comprises:
(1) A step of preparing a solution containing a functional substance (2) A step of coating a solution on a multifilament (3) A step of solidifying the stock solution. The production process of the sea-island fiber of the present invention will be described by taking as an example a case where a mixture of cerium particles and PVDF is a sea component and a polyester multifilament is an island component, but is not limited thereto.

(2-1) Step of preparing a stock solution containing a functional substance First, a stock solution containing a functional substance is prepared. This stock solution has a solution viscosity at 45 ° C. in the range of 0.1 to 100 Pa · s. It is preferable to adjust so that. Furthermore, it is preferable to adjust so that it may become the range of 0.1-50 Pa.s. Since the solution viscosity is in the above range, the solution can easily enter the multifilament by coating with a nozzle, which will be described later, so that the area ratio of the island component in the circle with a diameter of 2 / 3D from the center of the cross section is based on the total component. Sea-island fibers that are 10% or more and 50% or less can be obtained. When coating the core fiber, a stock solution having a low viscosity of generally 0.1 Pa · s or less is generally used. In this case, as shown in FIG. 4 or FIG. 7, the fiber has a low resin holding amount, but the resin holding amount becomes high by using a relatively high viscosity stock solution of 1 Pa · s or more. On the other hand, when the viscosity of the resin is too high, productivity is likely to decrease due to yarn clogging in a liquid draining process at the time of coating. Therefore, the viscosity is preferably 100 Pa · s or less, and more preferably 50 Pa · s or less.

  A mixture of polyacrylic acid and a crosslinking agent and / or a polyacrylic acid copolymer in which acrylic acid and a crosslinking site are copolymerized can be considered.

  When the sea component contains the above-described resin having a carboxy group, the coating stock solution is a solution containing the above-described resin and a solvent for dissolving the resin. Since the compound having a carboxy group is easily dissolved in water or the like, it is preferably crosslinked as described above. Examples of the crosslinking method include a method in which a covalent bond is formed by reacting with a compound having a carboxy group such as hydroxyl group, amino group, glycidyl group, oxazoline group, carbodiimide group in the molecule. These compounds having two or more functional groups that react with a carboxy group may be cross-linked between molecules, or a monomer having these functional groups and a monomer having a carboxy group may be copolymerized to form a linear polymer. Then, it may be crosslinked in the molecule.

2-2. The step of coating the solution on the multifilament The solution containing the functional substance is impregnated with the multifilament, and then passed through the nozzle. As the nozzle used here, for example, a nozzle described in JP-A-2004-314059 can be used. The coating method through a nozzle is used when producing a straw-like porous fiber called a hollow fiber membrane. The present invention has been found that by applying nozzle coating to a multifilament, the solution enters the multifilament, and as a result, sea-island fibers are obtained. In the conventional nip method, excess solution is drained by two upper and lower rolls, and the solution flows left and right while the multifilament is crushed, and only the fibers shown in FIG. 4 or FIG. 5 are obtained. It was. On the other hand, by passing through a nozzle as shown in FIGS. 8 and 9, the core fiber is not crushed excessively or the solution does not flow, and the solution enters the multifilament. It was found that the sea-island fiber shown in FIG. 3 was obtained.

  A nozzle suitable for producing the sea-island fiber of the present invention will be described with reference to FIGS. The multifilament introduced into the body 5 from the inlet 4 is immersed in the coating stock solution injected from the inlet 6. Thereafter, the coating fiber having the coating stock solution attached inside and outside the multifilament is led out from the outlet shown by 9 in FIG. 8 and 13 in FIG. Then, the sea-island fiber of this invention can be obtained through the process of solidifying the coating stock solution adhering to coating fiber.

  The diameter of the outlet port is important in the nozzle, and the lower limit of the outlet port diameter is preferably 70% or more, more preferably 90% or more, and more preferably 100% or more with respect to the diameter D of the sea-island fiber to be obtained. More preferably. In order to infiltrate the stock solution into the multifilament, it is important to maintain the gap between the filaments without crushing the multifilament. When the ratio is 70% or more, the gap is maintained and the stock solution enters the multifilament. It becomes easy. On the other hand, the upper limit is preferably 200% or less, more preferably 180% or less, and even more preferably 160% or less. By being 200% or less, the stock solution can enter the multifilament, and excess stock solution adhering around the multifilament can be drained.

  Further, in order to increase the amount of the stock solution entering the multifilament, it is more preferable to provide the outlet pipe 7 having a tapered structure gradually narrowing toward the outlet as shown in FIG. According to the principle of fluid lubrication in hydrodynamics, when a lubricating material is allowed to flow between two surfaces and the distance between the two surfaces is narrow along the flow direction of the lubricating material, the flowing lubricating material In this case, a lubricating film pressure is generated in a direction orthogonal to the flow, and the lubricating substance is expanded in the width direction. This is called a squeezing film pressure action (squeeze action), but this is also used in the present invention. That is, the inner surface of the tapered lead-out pipe portion and the outer surface of the multifilament correspond to the two surfaces described above, and the stock solution used corresponds to the lubricating material. In the undiluted solution flowing through the gap formed between the inner surface of the outlet pipe portion and the outer surface of the multifilament, a pressing force is generated in a direction orthogonal to the flow direction when passing through the gap. Therefore, when the multifilament and the undiluted solution are passed through the tapered portion together, the undiluted solution enters the multifilament even though the undiluted solution is subjected to the squeezing and pressing action. At this time, if the outlet pipe is made of an elastic member, an excessive external force (pressing) acts in the vicinity of the outlet, and the outlet pipe part made of the elastic member is deformed to maintain an equilibrium with the external force. . In other words, even if the outer diameter fluctuates, it is reversibly deformed and uniform pressing occurs. When this nozzle coating is applied to the hollow fiber membrane, a uniform pressure is applied from the outer peripheral portion, so that the effect of uniform coating thickness can be obtained. With a simple press, the undiluted solution enters the multifilament and sea-island fibers are obtained. Further, the expansion of the outlet tube part can alleviate the yarn clogging and can prevent the yarn clogging in the continuous coating.

  Further, it is more preferable that a diameter adjusting portion 8 is provided between the outlet pipe and the outlet. Liquid draining is performed uniformly in the diameter adjusting section, and the outer diameter D of the obtained sea-island fibers is uniform. The diameter adjusting portion is preferably attacked by a deformable elastic member in the same manner as the outlet tube.

As the elastic member constituting the outlet pipe to the outlet, the static shear elastic modulus due to tension, which is one of the indices of the elastic coefficient indicating the repulsive force, is in the range of 0.5 to 2 M Pa, and It is preferable that the elongation at break is in the range of 150 to 40%. Specifically, a thermoplastic resin or rubber is preferable, and among them, isoprene rubber, styrene butadiene rubber, butadiene rubber, butyl rubber, ethylene propylene rubber, and silicone rubber that have both solvent resistance and mechanical strength against the solvent used in the coating stock solution. It is more preferable to use etc. The static shear modulus was measured by measuring 25% elongation stress σ 2 5 (MPa) by 5 (low deformation tensile test) of JIS K 6 2 5 4 The elastic modulus is calculated, and the elongation at break is the value according to JIS K 6251 (a vulcanized rubber tensile test method).
GS = 1.639σ2 5
Here, G S is a static shear elastic modulus (MPa). When the elastic coefficient of the elastic member is in the above range, sea-island fibers having a uniform outer diameter can be obtained by generating a uniform pressing pressure.

  In addition, the parts other than the outlet port from the outlet pipe portion such as the nozzle body may be made of the same member as the outlet pipe portion, but from plastics such as polyethylene and polypropylene, metals such as stainless steel, solvent resistance and machine Can be selected in consideration of the mechanical strength.

  Fiber When the sea-island fiber of the present invention is produced, the core fiber used as a raw material must be a multifilament, and the number of filaments is preferably 12 or more, more preferably 36 or more. Since the number of filaments is 12 or more, it becomes easy to keep the stock solution immersed in the multifilament when the core fiber and the coating stock solution are passed through the nozzle. It can be manufactured easily. Further, the fiber diameter d of one filament in the core fiber is preferably 1 μm or more, and more preferably 10 μm or more. When the fiber diameter d is 1 μm or more, yarn breakage does not occur at the time of coating, production efficiency is increased, and the strength of the manufactured fiber is increased. Further, the upper limit of the core fiber diameter d is preferably 50 μm or less, and more preferably 30 μm or less. When the upper limit of the fiber diameter d is 50 μm or less, it is easy to pass through the nozzle, the production efficiency is increased, and peeling of the resin of the fiber and the core fiber after manufacture is suppressed.

(2-3) Step of solidifying the coated stock solution The coated stock solution is solidified with respect to the coated fiber that has passed through the nozzle to obtain a fiber. Examples of the solidifying method include a method of solidifying by increasing the concentration of solid content by removing the solvent, and a method of solidifying the solid content dissolved in the solvent by phase separation from the solvent.
Examples of the method for removing the solvent include a method in which the solvent is heated to evaporate and then removed by drying. The heating method is not particularly limited, and a sheathed heater, a radiant heater, an infrared heater, hot air, or the like can be used. In this step, when the solvent is water, the drying temperature is preferably 100 ° C. or higher, more preferably 110 ° C. or higher. If the temperature is high, the drying process time can be shortened and the production efficiency can be increased. it can. On the other hand, if the temperature is too high, the water vapor is foamed to form voids, and the increase in volume results in a decrease in ion exchange capacity around the volume, so that the heating temperature is preferably 150 ° C. or lower. It is more preferable that it is below ℃. In addition to keeping the temperature in the steam range, it is preferable to perform hot air circulation because the drying efficiency can be further increased. Although it is preferable to adjust suitably as heating time, 1 minute or more is preferable and 3 minutes or more is more preferable. Moreover, it is preferable that heating time is 10 minutes or less, More preferably, it is 6 minutes or less. When the heating time is 10 minutes or less, the cost for this step can be kept low.

  In particular, solidification by phase separation is preferred to make the sea component porous. When solidifying using phase separation, known methods such as a non-solvent induced phase separation method and a thermally induced phase separation method are applied to the usable phase separation. In the case of non-solvent induced phase separation, phase separation is performed by dipping in a non-solvent after coating. As a non-solvent, many polymers generally use water because water becomes a non-solvent. In addition, mixing the non-solvent and the good solvent can change the phase separation behavior and control the porous structure of the coating layer. The temperature also affects the phase separation of the coating stock solution, and the structure changes, so it must be kept within a certain range. Thermally induced phase separation methods include solid-liquid phase separation methods in which polymer crystallization occurs, liquid-solid phase separation methods in which solvent crystallization occurs, and liquid-liquid phase separation methods in which phases are separated in a liquid-liquid state. It has been known.

3. Water purification filter In the present invention, the water purification filter is obtained by winding sea-island fibers around the outer periphery of a cylindrical perforated core material. The porous core material is preferably made of a porous synthetic resin, but may be perforated in a dense synthetic resin cylinder. The synthetic resin is preferably a polyolefin such as polyethylene or polypropylene, or a fluororesin such as PTFE or PFA, but is not limited thereto. A water purification filter is obtained by winding and laminating a woven or knitted fabric of a fibrous adsorbent around the outer periphery of the perforated core material.

  The diameter (outer diameter) of the perforated core material is preferably 5 mm to 50 mm, particularly 20 mm to 40 mm. The length of the perforated core material is not particularly limited, but a material having a diameter of 80 mm to 500 mm is usually highly versatile. The thickness of the layer around which the sea-island fiber wound around the perforated core material is wound is preferably about 5 mm to 50 mm, particularly about 10 mm to 40 mm, in order to ensure filtration performance and suppress filtration pressure loss. It is preferable to fix the end of the wound fibrous adsorbent to the outer peripheral surface of the woven or knitted wound body by welding, adhesion or the like. The wound end face is preferably sealed with a disk-shaped plate or the like.

  The porosity of the water purification filter is preferably 10% or more, more preferably 20% or more, and further preferably 30% or more. Further, it is preferably 70% or less, more preferably 60% or less, and further preferably 50% or less. By being 30% or more, the water flow resistance is low and the flow rate of the permeated water is high, and clogging due to turbidity is difficult to occur, and the water flow resistance over time is difficult to increase. By being 70% or less, when the raw water is passed through the filter for liquid filtration, the raw water can be suitably removed without causing a short pass, and sufficient to break through A sufficient amount of permeate can be obtained.

  For the water purification filter configured as described above, for example, the liquid to be treated is permeated from the inside of the perforated core material, and the permeated liquid is taken out from the outer peripheral surface of the woven or knitted wound body. In the usual case, the filter is placed coaxially with the casing in a cylindrical casing. And a to-be-processed liquid is permeate | transmitted from the inner side of a perforated core material to the direction of the outer peripheral surface of a filter, and a permeated liquid is made to flow out of a casing from the outlet on the one end surface side of this casing. At this time, if the fiber constituting the filter has an adsorption effect, the specific substance is adsorbed and removed. For this reason, it is preferable to use a solution containing harmful substances such as boron, arsenic, phosphorus and fluorine as the liquid to be treated, and to remove these harmful substances.

4). Water treatment method A water treatment method using the water purification filter will be described.

  The water treatment method removes at least one harmful substance selected from the group consisting of boron, arsenic, phosphorus and fluorine by allowing raw water to permeate through the membrane element and permeate the permeated water of the membrane element through the water purification filter. The process of carrying out. Although the kind of membrane element is not limited, a reverse osmosis membrane or a UF membrane is preferable. For example, boron in seawater is a component removed by the reverse osmosis membrane element, but it is not easy to reduce the boron concentration to a value suitable for drinking water even by reverse osmosis. In order to remove boron, it is conceivable to improve the boron removal performance by making the reverse osmosis membrane dense. However, if the reverse osmosis membrane is densified, the water permeation performance is lowered. Therefore, in order to obtain the same amount of permeated water as in the case of using a non-dense reverse osmosis membrane, the equipment is enlarged and the processing cost is increased. On the other hand, by using the water purification filter of the present invention, the boron concentration of finally obtained water can be reduced without densifying the reverse osmosis membrane (that is, without reducing the water permeability). . Here, boron is taken as an example, but the same applies to arsenic, phosphorus and fluorine.

  The “raw water” refers to water to be treated, and is a word including seawater, brine, groundwater, drainage, etc., and is not limited to a specific mode.

  Moreover, you may permeate | transmit a raw | natural water to a pre filter, before permeate | transmitting a reverse osmosis membrane element. The pre-filter mainly removes fine particles in the raw water and reduces the load on the reverse osmosis membrane.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

<Solution viscosity of coating stock solution>
The solution viscosity of the coating stock solution was measured with a rotary B-type viscometer (model: PV-II + Pro, manufactured by Brookfield, USA) while keeping the solution at 50 ° C. The rotor to be used and the number of rotations were appropriately selected according to the solution viscosity to be measured.

<Diameter of sea island fiber D>
The cross section of the sea-island fiber was observed with a scanning electron microscope (Scanning Electron Microscope, JXA-8530F manufactured by JEOL Ltd.) at a magnification of 20,000, and the major axis in the cross-sectional image was measured. The same operation was performed with 20 fibers, and the average value was defined as the diameter D of the sea-island fibers.

<Proportion of island components in the center of the cross section>
In the cross-sectional image obtained by the scanning electron microscope, when a circle is drawn so as to enclose the cross-section, the ratio (%) of the island component in the circle having a diameter of 2 / 3D from the center of the circle is expressed as (island It calculated by the area of a component / (area of a circle) x100.

<Abrasion resistance test>
The fiber of the present invention was packed in a module container (inner diameter: 10 cm, length: 100 cm) so that the filling rate was 40%. Next, the module container was filled with a 5000 ppm kaolin aqueous solution, and 100 L / min of air was continuously supplied from the lower part of the container for 10 days to perform air scrubbing. From the result, the mass change rate (%) before and after air scrubbing was calculated by 100− (mass after air scrubbing−mass of core fiber) / (mass before air scrubbing−mass of core fiber) × 100.

(Example 1)
8% by mass of an ethylene-vinyl alcohol copolymer (manufactured by Nippon Synthetic Chemical Co., Ltd., Soarnol E type) having an ethylene copolymerization ratio of 32 mol% and 60% by mass of 1,3-propanediol were stirred and dissolved at 150 ° C. Subsequently, a stock solution was obtained by mixing 32% by mass of cerium hydroxide having a particle diameter of 4.5 μm. This coating stock solution had a viscosity of 45 Pa · S. Next, it is tapered from an inner diameter of 3.2 mm, and a triangular cross section with a fiber diameter d of 20 μm, 36 filaments, and an irregularity of 1.8 is applied to a coating nozzle having a lead-out tube made of silicone rubber with a lead-out port of 0.4 mm. The multifilament made of PET was allowed to pass through, and at the same time, the coating stock solution was injected to coat the multifilament. Subsequently, the coating fiber is guided into water at a temperature of 25 ° C., and is wound up at a speed of 10 m / min with a Kozu winder through a process of solidifying the coating solution by non-solvent induced phase separation and a desolvation process by washing with water. The fiber of the present invention was obtained. The obtained fiber had a diameter D of 0.4 mm, a cross-sectional area ratio of the island component in a circle of 2 / 3D was 45%, and a mass change rate before and after air scrubbing was 0.2%.

(Example 2)
A fiber of the present invention was obtained in the same manner as in Example 1 except that the coating nozzle was provided with a lead-out tube having a tapered shape with an inner diameter of 3.2 mm and a lead-out port of 0.8 mm. The obtained sea-island fiber had a diameter D of 0.44 mm, a cross-sectional area ratio of the island component in a circle of 2 / 3D was 32%, and the mass change rate before and after air scrubbing was 0.6%. .

(Example 3)
The fiber of the present invention was obtained in the same manner as in Example 1 except that the coating nozzle was tapered from an inner diameter of 3.2 mm and the outlet port was 1 mm. The obtained fiber had a diameter D of 0.52 mm, an area ratio of island components in a circle having a diameter of 2 / 3D in a cross section was 18%, and a mass change rate before and after air scrubbing was 1.1%.

(Example 4)
A fiber of the present invention was obtained in the same manner as in Example 1 except that the coating nozzle was a simple hole having a lead-out port of 0.3 mm. The obtained fiber had a diameter D of 0.38 mm, the area ratio of island components in a circle having a diameter of 2 / 3D in a cross section was 48%, and the mass change rate before and after air scrubbing was 0.2%.

(Comparative Example 1)
The fiber of the present invention was obtained in the same manner as in Example 1 except that the coating nozzle was tapered from an inner diameter of 3.2 mm and the outlet port was provided with a outlet pipe having a diameter of 1.5 mm. The obtained fiber had a diameter D of 0.63 mm, an area ratio of island components in a circle having a diameter of 2 / 3D in the cross section was 8%, and a mass change rate before and after air scrubbing was 12.2%.

(Comparative Example 2)
A fiber of the present invention was obtained in the same manner as in Example 1 except that the coating nozzle was a simple hole with a 1 mm outlet port. The obtained fiber had a diameter D of 0.48 mm, a cross-sectional area ratio of the island component in a circle of 2 / 3D was 9%, and a mass change rate before and after air scrubbing was 9.3%.

(Comparative Example 3)
A fiber of the present invention was obtained in the same manner as in Example 1 except that the coating nozzle was a simple hole having a lead-out port of 0.2 mm. The obtained fiber had a diameter D of 0.34 mm, an area ratio of island components in a circle having a diameter of 2 / 3D in a cross section was 67%, and a mass change rate before and after air scrubbing was 22%. In addition, thread breakage occurred frequently during production.

(Example 5)
15% by mass of vinylidene fluoride homopolymer (Arkema, Kynar 760), 3% by mass of cellulose acetate (Eastman Chemical, CA-435-75S) and 82% by mass of N-methyl-2-pyrrolidone were stirred at 120 ° C. Then, a coating stock solution was obtained by mixing 13% by mass of cerium hydroxide (manufactured by Daiichi Rare Elemental Chemical) with a particle diameter of 4.5 μm. The coating stock solution had a viscosity of 64 Pa · S. Next, it is tapered from an inner diameter of 3.2 mm, and a coating nozzle having a lead-out tube made of silicone rubber with a lead-out port of 0.4 mm has a round shape with a fiber diameter of d15 μm, 36 filaments, and an irregularity of 1.0. A multifilament made of nylon 6 having a cross section was allowed to pass through, and at the same time, a coating stock solution was injected to coat the multifilament. Subsequently, the coating fiber is guided into water at a temperature of 25 ° C., and the coating solution is solidified by non-solvent organic phase separation, followed by dewatering by water washing, and wound by a Kozu winder at a speed of 10 m / min. The fiber of the present invention was obtained. In the cross section of the obtained fiber, the area ratio of the island component in the circle having a diameter of 2 / 3D was 45%, and the mass change rate before and after air scrubbing was 0.4%.

(Comparative Example 4)
A multi-filament made of nylon 6 having a fiber diameter d of 30 μm, 36 filaments, and a triangular cross section of 1.8 is used in a plain weaving machine to produce a woven fabric made of fibers with a warp and weft mesh count of 40 (pieces / inch). Next, the obtained woven fabric was dipped in the same coating stock solution as in Example 1, then drained with a mangle, and dipped in water. The obtained fiber had a diameter D of 0.26 mm, an area ratio of island components in a circle having a diameter of 2 / 3D in a cross section was 84%, and a mass change rate before and after air scrubbing was 13%.

(Comparative Example 5)
In Comparative Example 4, the steps of immersion in the coating stock solution, draining with mangle, and water immersion were repeated three times. The obtained fiber had a diameter D of 0.42 mm, an area ratio of island components in a circle having a diameter of 2 / 3D in a cross section was 81%, and a mass change rate before and after air scrubbing was 35%.

(Comparative Example 6)
A fiber was obtained in the same manner as in Comparative Example 4 except that a monofilament made of PET having a circular cross section with a fiber diameter of d300 μm was used. The obtained fiber had a diameter D of 0.34 mm, an area ratio of island components in a circle having a diameter of 2 / 3D in the cross section was 88%, and a mass change rate before and after air scrubbing was 54%.

(Comparative Example 7)
A fiber was obtained in the same manner as in Comparative Example 4 except that a monofilament made of PET having a circular cross section with a fiber diameter of d100 μm was used. The obtained fibers were evaluated as bundles of 36 fibers. The fiber had a diameter (bundle diameter) D of 0.52 mm, the area ratio of the island component in a circle having a diameter of 2 / 3D in the cross section was 59%, and the mass change rate before and after air scrubbing was 63%.

(Example 6)
Vinylidene fluoride homopolymer (Akema, Kynar 760) 13 mass, cellulose acetate (Eastman Chemical, CA-435-75S) 2 mass%, N-methyl-2-pyrrolidone 70 mass% at 120 ° C. It was obtained by stirring and dissolving, and then mixing 15% by mass of cerium hydroxide having a particle size of 4.5 μm. This coating stock solution had a viscosity of 94 Pa · S. Using the stock solution, the fiber of the present invention was obtained in the same manner as in Example 5. The obtained sea-island fiber had a diameter D of 0.43 mm, the area ratio of the island component in a circle with a diameter of 2 / 3D in the cross section was 41%, and the mass change rate before and after air scrubbing was 1.3%. .

(Example 7)
10 parts by mass of PVA (saponification degree 98%, molecular weight 1700), 10 parts by mass of hydrous cerium oxide (average particle size 4.5 μm), diisopropoxy bis (triethanolamine) titanium (Matsumoto Fine Chemical Co., Ltd.) 2 parts by mass of 80 wt% isopropanol solution (manufactured by company) was obtained by dissolving 78 parts by mass of water. Next, a multifilament made of PET having a triangular cross section with a fiber diameter of 30 μm, 36 filaments, and an irregularity of 1.8 is applied to a silicone rubber coating nozzle having a tapered shape from an inner diameter of 3.2 mm and an outlet port of 0.4 mm. The multifilament was coated by injecting the coating stock solution at the same time as passing through. Subsequently, the coated fiber was passed through a hot air drying furnace, dried at 110 ° C. for 1 minute and 130 ° C. for 0.5 minute, and wound up with a winder manufactured by Kozu Seisakusho at a speed of 4 m / min. Subsequently, the fiber of the present invention was obtained by performing heat treatment at 180 ° C. for 20 minutes in the wound state. The obtained fiber had a diameter D of 0.38 mm, a cross-sectional area ratio of the island component in a circle of 2 / 3D was 37%, and a mass change rate before and after air scrubbing was 0.5%.

(Example 8)
Acrylic acid (manufactured by Nippon Shokubai Co., Ltd.) 14% by weight, hydroxyethyl methacrylate (manufactured by Nippon Shokubai Co., Ltd.) 1% by weight is dissolved in distilled water 85% by weight, and ammonium persulfate (manufactured by Kanto Chemical Co., Ltd.) is added as an initiator. Then, the mixture was stirred at 53 ° C. for 4 hours for polymerization to obtain a stock solution. This stock solution was degassed and then kept at 60 ° C. Next, a round nozzle with a fiber diameter d of 20 μm, 12 filaments, and an irregularity of 1.0 is applied to a coating nozzle provided with a lead-out tube made of silicone rubber having a taper shape from an inner diameter of 3.2 mm and a lead-out port of 0.6 mm. A multifilament made of PET having a cross section was allowed to pass through, and at the same time, a coating stock solution was injected to coat the multifilament. Subsequently, the coated fiber was passed through a hot air drying furnace, dried at 110 ° C. for 1 minute and 130 ° C. for 0.5 minute, and wound up with a winder manufactured by Kozu Seisakusho at a speed of 4 m / min. Subsequently, the fiber of this invention was obtained by performing heat processing at 200 degreeC for 10 minutes in the wound state. The obtained fiber had a diameter D of 0.68 mm, the area ratio of the island component in a circle having a diameter of 2 / 3D in the cross section was 17%, and the mass change rate before and after air scrubbing was 0.2%.

  The sea-island fiber of the present invention provides a fiber having a functional sea component. In particular, the sea-island fiber is suitably used for removing harmful substances in water by using an adsorbent compound as a sea component.

1: Sea component 2: Island component 3: Core fiber 4: Coating filament multifilament inlet 5: Coating nozzle body 6: Coating nozzle stock injection port 7: Coating nozzle outlet tube 8: Coating nozzle diameter adjusting section 9: Coating nozzle outlet 10: Coated fiber 11: Coating solution injection tube 12: Liquid feed pump 13: Coating nozzle outlet There is a hole in the fuselage.

Claims (11)

The fiber diameter D is 100 μm or more and 1000 μm or less,
It has a sea-island structure that includes sea and island components,
A sea-island fiber in which the area ratio of the island component in a circle with a diameter of 2 / 3D from the center of the cross-section perpendicular to the longitudinal direction of the fiber is 10% to 50% with respect to the area of the circle with a diameter of 2 / 3D.   The sea-island fiber according to claim 1, wherein 40% by mass or more of the sea component is particles. The sea-island fiber according to claim 1 or 2, wherein 60% by mass or more of the island component is a thermoplastic resin. The island component comprises at least one polymer selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate and nylon;
Sea-island fiber as described in any one of Claims 1-3. The cross-sectional shape of the sea component is an irregular cross-section,
Sea-island fiber in any one of Claims 1-4. It is a manufacturing method of the sea-island fiber according to claim 1,
In a coating nozzle having a lead-out port having a diameter that is 80% to 200% of the diameter D of the sea-island fiber,
A method for producing sea-island fibers having a coating step of coating a sea component around a multifilament that is an island component by passing a multifilament having a fiber diameter d of 1 μm to 50 μm and having a filament number of 12 or more and a coating stock solution. . The said coating nozzle is a manufacturing method of the sea-island fiber of Claim 6 provided with the outlet tube which has a taper in which an internal diameter becomes small toward the said outlet. The lead pipe of the coating nozzle is made of an elastic resin having a static shear modulus coefficient in a range of 0.5 to 2 MPa and an elongation at break in a range of 150 to 400%. 7. A method for producing a sea-island fiber according to any one of the above. The sea-island fiber according to any one of claims 6 to 8, wherein the member constituting the lead-out pipe of the coating nozzle is an elastic resin selected from silicone rubber, isoprene rubber, styrene butadiene rubber, butadiene rubber, butyl rubber, and ethylene propylene rubber. Manufacturing method. The method for producing sea-island fibers according to any one of claims 6 to 9, wherein the coating stock solution has a solution viscosity of 1 Pa · s to 100 Pa · s. The method for producing sea-island fibers according to any one of claims 6 to 10, further comprising a step of removing the solvent from the coating stock solution after the coating step.