JPH08199480A - Production of separation functional fiber, and ion exchange fiber and gas adsorbing material produced by using the same - Google Patents

Abstract

PURPOSE: To obtain an ion exchange fiber and a gas absorbing material by irradiating an ionizing radiation to a fiber having a specific core-sheath structure and grafting the fiber with a polymerizable monomer. CONSTITUTION: An olefinic polymer such as a polyethylene capable of producing a radical by irradiating ionizing radioaction rays such as γ-rays or electron beam is arranged in the sheath part of a fiber and a polyethylene terephthalate hardly causing degradation due to irradiation is arranged in the core part to afford a core-sheath type fiber concentrically or eccentrically formed in a shear-core weight ratio of 0.1-10 and the ionizing radioactive rays are irradiated to the core-sheath type fiber or fabric or nonwoven fabric made therefrom in which sheath parts of adjacent fibers are fused or its processed product, and then, the fiber is grafted with a polymerizable monomer such as glycidyl methacrylate to form the objective separation functional fiber. The core-sheath structure fiber or the separation functional fiber is subjected to radiation graft polymerization with a monomer other than styrene to provide the objective ion exchange fiber, and the objective gas adsorbing material is obtained by using the separation functional fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation functional fiber, and more particularly to a method for manufacturing a separation functional fiber using radiation graft polymerization and an ion exchange fiber and a gas adsorbent obtained by using the method. It is a thing.

[0002]

2. Description of the Related Art Clean rooms are used not only in the advanced industries such as semiconductor industry, precision machinery industry, photographic industry, pharmaceutical manufacturing industry, and biological clean rooms such as hospitals, but also recently in food industry, agriculture field, and other peripheral industries. The field of application is expanding to. As environmental conditions in such industrial fields, air purification is extremely important in addition to temperature, humidity, and air flow. Air purification in these industries is a high performance filter that uses glass fiber as a constituent component.
EPA (High Efficiency Parti)
create Air) filter and more efficient ULP
A (UltraLow Penetration Ai
r) A filter is used. Also, as prefilters for these filters, medium-performance fibers containing synthetic fibers other than glass fibers as constituent components, coarse dust filters, etc. are often used. The above filters are intended to remove particles, and are designed so that even particles of about 0.1 μm can be removed efficiently. However, the effect of removing gas and ions cannot be expected.

In the current LSI manufacturing factory, contamination of the wafer surface is considered to be caused by both fine particles and gases and ions. In particular, the latter contamination causes problems such as an increase in contact resistance and an influence on the characteristics inside the wafer. There are various sources of gas and ions, such as a manufacturing process such as etching, a clean room finishing material, and mixing when introducing outside air.
The generated gas and ions are not removed by the air purification system despite being circulated in the clean room, so they are gradually accumulated, and it is feared that not only the quality of the product but also the health of the worker may be affected. There is.

Separation-functional fibers or ion-exchange fibers are cobalt contained in water and wastewater in the fields of precision electronics industry, medical care, pharmaceuticals, nuclear power generation, food industry, etc., as disclosed in JP-A-5-111685. , Nickel,
It is possible to effectively adsorb and remove heavy metal ions such as mercury and copper. Also, Japanese Patent Publication No. 5-67325, Japanese Patent Laid-Open No. 5-111607, and Japanese Patent Laid-Open No. 6-142439.
In the publication, it is shown that fine particles in the gas and H ₂ S, NH ₃ , carbon dioxide and hydrogen fluoride can be removed by a filter of ion exchange fiber. However,
These conventional fibers have not been able to remove such from the gas sufficiently effectively.

Japanese Examined Patent Publication No. 6-
20554 (US patent application No. 08/264,
No. 762), the ion exchange fiber adsorbs hydrogen chloride and ammonia in the air in the examples therein, but more effective adsorption of hydrogen chloride and ammonia is desired.

The rate of adsorption or ion exchange increases as the surface area increases and the density of functional groups on the surface area increases. This is because the adsorption or ion exchange reaction first occurs on the surface of the fiber and gradually progresses to the inside, so that the internal functional groups cannot be said to be fully utilized. Therefore, it is advantageous that the functional groups are densely present on the fiber surface.

On the other hand, the radiation graft polymerization method is easy to control the field of the graft polymerization and has attracted attention as a method of producing a separation functional material, and ion exchange fibers and adsorbents by this method have been studied. The radiation graft polymerization method is generally a pre-irradiation liquid phase graft polymerization method in which a base material is irradiated with ionizing radiation and then immersed in a monomer solution for reaction. In this case, graft polymerization occurs near the surface of the base material at the initial stage of the reaction, and the polymerization proceeds to the inside of the base material as the reaction time elapses. Therefore, it is difficult to concentrate the graft polymerization near the surface at a sufficiently high graft rate of 100% or more. Even in the gas phase graft polymerization method, at a high graft ratio, the graft polymerization proceeds to the inside of the substrate. Therefore, even in the radiation graft polymerization, it was not easy to produce a fibrous separation functional material in which functional groups such as ion-exchange groups are concentrated on the surface.

Further, when the reaction proceeds to the inside of the substrate by applying radiation graft polymerization, the physical strength is lowered when a substrate such as polypropylene is used, and oxidative deterioration occurs to release decomposition products. There was a problem such as doing. As the closest prior art to this, a method for producing a gas adsorbent in which an ion exchange group is introduced into a base material of polypropylene fiber having no core-sheath structure by radiation graft polymerization is disclosed in Japanese Patent Publication No. 6-2.
It is known as Japanese Patent No. 0554.

In general, a separation functional material such as an ion exchange material or an adsorbent has a larger exchange rate or adsorption rate as the surface area is larger, which is advantageous. Therefore, the frequency of using a fibrous ion exchange material or adsorbent having a large surface area is increasing. As an example of the fibrous separation functional material, ion-exchange fiber will be explained. Currently, polystyrene is the base material (matrix).
Or, in the sea, there is a fiber with a multi-core structure in which polyethylene is a filamentous multi-core or islands in the base material, and an ion exchange group is introduced into the base material part, or a polyvinyl alcohol fiber fired It is known that an ion exchange group is introduced.

In Example 3 of Japanese Patent Application Laid-Open No. 5-64726, an electrically regenerative desalting apparatus is ion-exchanged with polypropylene as a core, polyethylene as a sheath, and a composite fiber converted after grafting a styrene monomer. It shows very excellent results when used as a fiber, and it is shown that the ion-exchange fiber having a core-sheath structure is excellent even when applied to an electric regenerative desalination apparatus. However, when the fiber whose core is polypropylene is used in the atmosphere, the strength and decomposition of polypropylene of the core occur, but by replacing this core with polyethylene terephthalate, which has good radiation resistance and oxidation resistance, It has been found in previous studies that it is stable even in the atmosphere.

In recent years, gas adsorption filters made of ion-exchange fiber as a material have been developed for clean rooms, in addition to materials supporting activated carbon, zeolite, and manganese oxide to which chemicals have been added. Among them, JP-A-6-14243
As shown in No. 8 (Japanese Patent Application No. 4-294501),
The one using the ion exchange fiber of the polymer resin produced by the radiation graft polymerization has shown very good results as the gas adsorbent in the clean room.

JP-A-6-142438 (Japanese Patent Application No. 4-2)
No. 94501), as a method for purifying a trace amount of contaminated air in a clean room, a method for purifying air in a clean room by making a non-woven fabric filter of polymer ion exchange fibers by radiation graft polymerization is shown. In the examples in these, as a raw material for irradiating with ionizing radiation, a non-woven fabric of polypropylene fiber, a non-woven fabric of composite fiber composed of polyethylene and polypropylene is used.However, polypropylene and polyethylene have acidic substances due to radiation irradiation and the presence of oxygen. The problem is that they are easily generated, and further deteriorate due to irradiation and easily generate dust.

[0013]

In the future, it is inevitable that the cleanliness in the clean room will become more severe than it is now, and therefore, the dust generated from the filter itself and the generation of gaseous substances will be further increased. The problem is clear. For this reason, in the present invention, a polymer component that is less likely to cause radical generation and / or polymer collapse by irradiation with ionizing radiation is used as a core, and conversely, a polymer component that is easy to generate radicals is used. By forming the sheath on this core,
Prevents dust generation and gaseous substances from the filter itself.

The present invention solves the above-mentioned problems of the prior art and is based on a method for producing a separation functional fiber by radiation graft polymerization in which functional groups are densely introduced on the surface of the fiber and physical and chemical deterioration is small. An ion exchange fiber and a gas adsorbent are provided. That is, the ion-exchange fiber and the gas adsorbent produced from the separation-functional fiber of the present invention can more effectively remove the gas pollutants in the gas, and particularly not only the fine particles in the clean room but also the trace amount thereof. It is possible to purify air contaminated with gas, ions and the like.

[0015]

In view of the above, according to the present invention, first, a fiber having a core-sheath structure is irradiated with ionizing radiation, and then a polymerizable monomer is graft-polymerized on the fiber to obtain an ion exchange property and a chelate property. It is a method for producing a separation functional fiber having various properties such as. That is, the method for producing a separation-functional fiber is characterized in that a fiber having a core-sheath structure made of different polymers is irradiated with ionizing radiation and then a polymerizable monomer is grafted onto the fiber.

Next, the present invention is produced by introducing an ion-exchange group into the sheath of a composite fiber having a core-sheath structure having a core and a sheath made of different types of polymer components by radiation graft polymerization. Ion exchange fiber and gas adsorbent. That is, the core portion and the sheath portion of the fiber having a core-sheath structure are composed of different polymer components, and by introducing a ion-exchange group into the sheath portion of the fiber through radiation graft polymerization of a monomer other than styrene. Produced ion-exchange fiber, the sheath part is a component that is easy to generate radicals by irradiation of ionizing radiation, and the core part is a component that is hard to generate radicals and / or collapse of polymers by irradiation of ionizing radiation. Which is a gas adsorbent produced by irradiating a fiber having a core-sheath structure with ionizing radiation and then grafting a polymerizable monomer on the sheath.

Next, the structure of the present invention will be described in detail.

FIG. 1 shows a cross section of a fiber having a core-sheath structure. A fiber having a core-sheath structure as shown in FIG. 1 is a structure in which a sheath portion 2 surrounds a core portion 1. As shown in FIG. 1A, the core portion and the sheath portion are concentric circles. However, it may be eccentric instead of being concentric as shown in FIG. 1 (b), and as shown in FIG. 1 (c), the sheath 2 forming the sea or matrix forms an island forming a multicore. The islands and islands type in which 1 is scattered may be used.

Further, the material of the fiber having the core-sheath structure is such that the sheath portion is a material capable of generating radicals by irradiation of ionizing radiation, and the core portion generates and / or radicals by irradiation of ionizing radiation. A material that does not easily cause the polymer to collapse is preferable.

Furthermore, it is preferable that the material of the core portion has a higher melting point than the material of the sheath portion. The reason is that the core-sheath fiber can be made into a non-woven fabric by a heat fusion method. Particles such as crushed pieces of fiber because each fiber is fused at the sheath
Is extremely rare. This is an extremely important characteristic for water treatment and air treatment in the precision electronics industry, nuclear power generation, etc. to which the present invention is applied.

Specifically, a polyolefin-based material is suitable as the material for the sheath, because a material suitable for radiation graft polymerization is used for the sheath. Polyolefins represented by polyethylene and polypropylene,
Polyvinyl chloride and polytetrafluoroethylene (PTF
E) halogenated polyolefins, copolymers of olefins and halogenated polyolefins represented by ethylene-tetrafluoroethylene copolymers, ethylene-vinyl alcohol copolymer (EVOH), ethylene-vinyl acetate Copolymers of olefins represented by (EVA) and the like with other monomers are suitable materials. In particular, polyethylene is excellent as the sheath component of the ion exchange fiber.

The material of the core portion can be selected from those different from the material of the sheath portion, and a material that can maintain the strength of the fiber after radiation graft polymerization to the sheath portion is preferable. Especially when the core material of polyolefin cannot be used,
Polyesters represented by polyethylene terephthalate and polybutylene terephthalate are suitable as the core material.

Examples of the combination of materials of the core / sheath include polyethylene (sheath) / polypropylene (core), polyethylene (sheath) / polyethylene terephthalate (core), and the like. Particularly, the material of polyethylene / polyethylene terephthalate excellent in radiation resistance. However, the present invention is not limited thereto.

The weight ratio of the sheath portion to the core portion of the fiber having the core-sheath structure is preferably in the range of 0.1 to 10. If it is 0.1 or less, the graft ratio of the sheath portion must be made extremely high in order to obtain a sufficient amount of the functional group, and the strength becomes weak and the core-sheath structure cannot be maintained. When it exceeds 10, it becomes almost the same as the single fiber of the material of the sheath portion, and the effect of forming the core-sheath structure disappears.

As shown in FIG. 7, when graft polymerization is performed on the sheath portion of the fiber having a core-sheath structure, the dimension of the sheath portion increases and the core portion is separated. That is, there is no gap between the core and the sheath before grafting, but after the graft polymerization, there is a gap between the core and the sheath, resulting in folds in the sheath. Then, after the introduction of the functional group, the gap is further expanded and the folds are expanded.

8 to 11, the core portion is polyethylene terephthalate (PET) and the sheath portion is polyethylene (PE).
Before grafting of the composite fiber of FIG. 8 (FIG. 8), grafting of about 116% of glycidyl methacrylate (FIG. 9), and further after sulfonation (FIG. 10) or amination (FIG. 11). The cross-section photograph of the composite fiber is shown.

A large number of folds are observed in the sheath after grafting, as compared with the smooth surface before grafting. Since the surface of the sheath portion has many undulations in this manner, the surface area increases, which is not only preferable for improving the adsorption separation rate, but also increases the physical capturing function of the fine particles. Further, the peeling of the core-sheath has a function of enhancing the water retention performance of the entire fiber. This phenomenon is advantageous in that when the separation functional fiber according to the present invention, particularly the ion exchange fiber is used as an air filter for removing harmful gases such as acidic and alkaline gases, performance deterioration due to drying can be prevented. Although the physical strength is slightly deteriorated by the graft of the sheath, the strength of the fiber as a whole is maintained in the core.

The shape of the fiber having the core-sheath structure can be applied to long fibers and short fibers. It can also be applied to woven or non-woven fabrics, which are aggregates of fibers, or processed products thereof.

The following method can be applied as a method for radiation-induced graft polymerization of a fiber having a core-sheath structure as a base material.

First, α rays and β are used as the radiation irradiation source.
Various kinds of rays such as rays, γ rays, electron rays, X rays and ultraviolet rays can be used, but γ rays and electron rays are suitable for the present invention. The irradiation dose is preferably 20 to 300 kGy. 20 kG
If y or less, sufficient radicals are not generated for the reaction. 300
When it is equal to or higher than kGy, there is a problem that radiation deterioration becomes large and irradiation cost becomes high.

A method of graft-polymerizing by contacting a polymerizable monomer (monomer) after irradiation with radiation in advance is called a pre-irradiation graft polymerization method, and is a simultaneous irradiation method in which a base material is irradiated with radiation in the presence of the monomer. Compared with the above, since the amount of the homopolymer produced is small, it is suitable as a method for producing the separation functional fiber as in the present invention.

The case where the irradiated substrate is graft-polymerized while being immersed in the monomer solution is called liquid-phase graft polymerization, and a reaction temperature of 20 to 60 ° C. and a reaction time of 2 to 10 hours are suitable.

The impregnation graft polymerization in which a predetermined amount of the monomer is applied to the irradiated substrate and the reaction is performed in a vacuum or in an inert gas is suitable for a reaction temperature of 20 to 60 ° C. and a reaction time of 0.2 to 8 hours. In this case, since the base material after the graft polymerization is in a dry state, there are advantages such as easy handling of the base material and a small amount of waste liquid generated.

The vapor phase graft polymerization in which the irradiated substrate and the monomer vapor are brought into contact with each other can be applied only to a monomer having a relatively high vapor pressure, and graft unevenness is likely to occur, but the amount of waste liquid generated is small and after the graft polymerization. It has the advantage that the substrate is dry. In this case, the reaction temperature is 20 to 8
A reaction time of 2 to 10 hours is required at 0 ° C.

In the present invention, any of the above radiation graft polymerization methods can be used. As the polymerizable monomer,
A polymerizable monomer having various functions or a polymerizable monomer having a function introduced by a secondary reaction after grafting can be used. For example, in the case of ion-exchange fiber, there are acrylic acid, methacrylic acid, sodium styrene sulfonate, sodium methacryl sulfonate, sodium allyl sulfonate, etc. as the monomer having an ion exchange group, and the ion exchange can be performed only by graft-polymerizing these. Fibers are obtained.

Monomers capable of introducing an ion-exchange group by further reacting after graft polymerization include acrylonitrile, acrolein, vinylpyridine, styrene, chloromethylstyrene, glycidyl methacrylate and the like.
For example, in the glycidyl methacrylate graft product, a sulfone group can be introduced by using a sulfonating agent such as sodium sulfite.

As the application of the method for producing the separation-functional fiber of the present invention, the ion-exchange fiber was mainly described, but the present invention is also applicable to a heavy metal adsorbent having a chelate group, a catalyst, a carrier for affinity chromatography and the like. Is applicable.

[0038]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1 A non-woven fabric (weight per unit area of 50 g / m ² ) composed of composite fibers of core polypropylene and sheath polyethylene (weight ratio of core / sheath: 1) having an average diameter of 20 μm was irradiated with γ-rays in a nitrogen atmosphere at 200 kGy. Then, it was immersed in a 50% aqueous solution of acrylic acid and reacted at 40 ° C. for 6 hours to obtain a graft ratio of 53%. The ion exchange capacity was 4.8 meq / g.

When this fiber was converted to Na type with sodium hydroxide and the cross section was observed with an X-ray microanalyzer, sodium distribution was observed only in the polyethylene of the sheath.

This non-woven fabric (H type) was punched out to a diameter of 20 mm, and the glass column of the gas adsorption experimental apparatus shown in FIG.
4 g was filled, the test gas was circulated at 3 l / min, and the ammonia gas removal test was conducted.

In FIG. 2, 3 is a fluororesin bag (4
0l), 4 is a glass column (20 mmφ), and the nonwoven fabric 5 is filled therein. Reference numeral 6 is a pump, 7, 8 and 9 are sampling portions for sample analysis, and 10 is a flow meter.

The results are shown in FIG. 3 as-○-. As shown in FIG. 3, in the nonwoven fabric using the fiber of the present invention, the ammonia concentration in the fluororesin bag 3 was 40 ppm at the initial stage, but was reduced to 10 ppm or less in about 50 minutes, and after 5 hours, the ammonia concentration was 5 ppm.
It became below ppm.

Comparative Example 1 A polypropylene single fiber having an average diameter of 20 μm,
A non-woven fabric having a basis weight of 40 g / m ² was subjected to radiation-induced graft polymerization of acrylic acid in the same manner as in Example 1 to obtain a graft ratio of 58%. The ion exchange capacity of this fiber was 5.0 meq / g, and the ion exchange groups were distributed relatively uniformly to the center of the fiber.

This fiber was punched out in the same manner as in Example 1 and
Ammonia gas removal test was conducted using the gas adsorption experimental device. The results are also shown in FIG. 3 as -Δ-, but it took 1 hour and 50 minutes for the ammonia concentration in the fluorine bag to drop to 10 ppm or less.

Example 2 A nonwoven fabric (weight per unit area: 40 g / m ² ) made of a composite fiber of a core polypropylene and a sheath polyethylene (core-sheath weight ratio of 1) having an average diameter of 20 μm was irradiated with γ rays in a nitrogen atmosphere at 200 kG.
After y irradiation, it was immersed in a glycidyl methacrylate / methanol (1/1) solution and reacted at 45 ° C. for 7 hours to obtain a graft ratio of 138%. This grafted fiber was immersed in an aqueous solution of sodium sulfite and reacted at 80 ° C. for 8 hours for sulfonation. This fiber has an ion exchange capacity of 2.4.
It was a strongly acidic cation exchange fiber of 2 meq / g, and almost all of the sulfone groups were distributed in the sheath.

This fiber (H type) was punched out into 20φ, and an ammonia gas removal test was conducted under the same conditions as in Example 1 using the apparatus of FIG. The results are shown as-○-in Fig. 4, but the ammonia concentration in the fluorocarbon resin bag was 40 at the initial stage.
Although it was ppm, it decreased to 10 ppm or less within 20 minutes.

Comparative Example 2 A non-woven fabric made of polypropylene single fiber having an average diameter of 20 μm and having a basis weight of 40 g / m ² was subjected to radiation graft polymerization of glycidyl methacrylate in the same manner as in Example 2 to obtain a graft ratio of 135%. Then, sulfonation was performed in the same manner as in Example 2 to obtain a strongly acidic cation exchange fiber having an ion exchange capacity of 2.45 meq / g. The sulfonic groups of this fiber were relatively evenly distributed near the center of the fiber.

The fibers were punched into 20φ in the same manner as in Example 2,
When an ammonia gas removal test was conducted using the apparatus shown in FIG. 2, the result was as shown by -Δ- in FIG. 4, and it took 35 minutes for the ammonia concentration in the fluororesin bag to reach 10 ppm or less.

As compared with Examples 1 and 2 and Comparative Examples 1 and 2, the fiber having the core-sheath structure of the present invention was more ammonia than the fibers having the same graft ratio, kind of functional group and ion exchange capacity. It is clear that the gas removal performance is excellent.

Example 3 A non-woven fabric (unit weight: 55 g / m ² ) made of a composite fiber of concentric polyethylene terephthalate having a mean diameter of 20 μm and sheath polyethylene (weight ratio of the sheath core was 0.7) was irradiated with an electron beam of nitrogen. After irradiation with 100 kGy in the atmosphere, glycidyl methacrylate was reacted in the same manner as in Example 2 to give a graft ratio of 1
A 16% graft nonwoven was obtained. This nonwoven fabric was immersed in an ethylenediamine solution and reacted at 50 ° C. for 3 hours to obtain a nonwoven fabric having a chelate group with an acid adsorption amount of 5.3 meq / g. Almost all the chelating groups of the fibers of this non-woven fabric were distributed in the sheath.

This non-woven fabric was punched out into 20φ and 0.5 g was sampled. This is an aqueous solution of copper sulfate (concentration 110 mg / l
AsCu) was immersed in 300 ml, and the change with time of the copper concentration was examined while stirring. The result is as shown by-○-in FIG. 5, and the copper concentration decreased to 20 mg / lasCu in 1 minute.

A cross-sectional photograph of the non-woven fiber used as the base film in Example 3 is shown in FIG. 8, a cross-sectional photograph of the fiber after grafting is shown in FIG. 9, and a cross section of the fiber aminated with an ethylenediamine solution after grafting is shown. It shows in FIG.

Comparative Example 3 A non-woven fabric composed of polyethylene single fibers having an average diameter of 20 μ (weight per unit area: 60 g / m ² ) was irradiated with an electron beam under the same conditions as in Example 3, and then reacted with glycidyl methacrylate to give a graft ratio of 131%. A graft nonwoven fabric of Further, it was reacted with ethylenediamine under the same conditions and the acid adsorption amount was 5.1.
A non-woven fabric having a chelate group of 9 mq / g was obtained. The chelate groups of this non-woven fiber were evenly distributed near the center of the fiber.

This non-woven fabric was punched out into 20φ in the same manner as in Example 3 and immersed in a copper sulfate solution to examine changes in copper concentration with time.
The results are as shown in FIG. 5 as -Δ-, which was reduced to about 40 mg / lasCu in 1 minute.

It is clear from Example 3 and Comparative Example 3 that the fibers having the core-sheath structure of the present invention have a better heavy metal adsorption performance regardless of the graft ratio and the functional group concentration which are almost the same. .

Example 4 (a) A non-woven fabric made of concentric polyethylene (PE) (sheath) / polypropylene (PP) (core) fibers (diameter about 17 μm) having a basis weight of 50 g / m ² was irradiated with gamma rays in a nitrogen atmosphere. Was irradiated, and then glycidyl methacrylate was graft-polymerized. A graft rate of 153% was obtained.

This non-woven fabric was immersed in a sulfonation solution containing 8% of sodium sulfite, 12% of isopropyl alcohol and 80% of water, and reacted at 80 ° C. for 8 hours for sulfonation.
Further, it was immersed in 7% hydrochloric acid and replaced with an H type. This fiber is (a) PE / PP.

(B) Next, concentric polyethylene (P
E) (sheath) / polyethylene terephthalate (PET)
50 g / unit weight consisting of (core) fibers (diameter about 17 μm)
Graft polymerization, sulfonation and regeneration were carried out on m ² in the same manner as in the above (a). This fiber is (b) PE / PET
And The cross section of this fiber is shown in FIG.

The tensile strength of the non-woven fabric of the fibers (a) and (b) is shown in FIG. In the figure, (a) PE / PP is-○-
PE / PET of (b) is indicated by -Δ-. Thus, it can be seen that the tensile strength does not decrease with the irradiation dose of radiation when PE / PET of (b) is used.

Next, a test was conducted to confirm the release of degradable products due to the chemical deterioration of the fibers. In general, even in the case of synthetic polymer-based ion exchangers, deterioration of the polymer skeleton due to oxidation, and accompanying formation of low-molecular decomposition products and elimination of functional groups are unavoidable. There is a greater need for ion exchangers that are highly resistant.

In order to evaluate the release of decomposition products due to this deterioration, PE / PP of (a) above and PE / PE of (b) above are evaluated.
Air in a container containing about 200 g of T non-woven fabric (20 cm × 4 cm) at 1 liter / min. The decomposition products contained in the exhaust gas that were circulated in 1. were collected with ultrapure water and analyzed. TOC was measured to evaluate the organic low-molecular-weight decomposition products, and the concentration of sulfate ion was measured by ion chromatography to evaluate the elimination of ion-exchange groups. Table 1 shows the results.

[0063]

[Table 1] Example 5 (removal of SO ₂ ) γ rays were applied to the same nonwoven fabric as in Example 1 at 200 k in a nitrogen atmosphere.
After Gy irradiation, it was dipped in a solution of glycidyl methacrylate to impregnate 150% by weight of the substrate. After putting this non-woven fabric into a glass ampoule and reducing the pressure with a vacuum pump, 4
The reaction was carried out at 5 ° C for 3 hours to obtain a graft ratio of 141%. The grafted nonwoven fabric was immersed in a 30% aqueous solution of iminodiethanol and reacted at 70 ° C. for 3 hours to obtain a weakly basic anion exchange nonwoven fabric having an ion exchange capacity of 2.89 meq / g.

This non-woven fabric was punched out to 20φ and Example 1 was used.
A sulfur dioxide (SO ₂ ) removal test was carried out using the above apparatus. The initial concentration of SO ₂ in the fluorine bag is 30 ppm
Fell to 1 ppm or less in 40 minutes.

Example 6 (Removal of CO ₂ ) The same nonwoven fabric as in Example 1 was irradiated with the same radiation, and then immersed in a solution of chloromethylstyrene (CMS),
The reaction was carried out at 40 ° C for 7 hours to give a CMS graft ratio of 1
12% non-woven fabric was obtained. This non-woven fabric was immersed in a 10% aqueous solution of trimethylamine and subjected to a quaternary ammonium formation reaction at 50 ° C. for 3 hours. This non-woven fabric was immersed in a 5% aqueous sodium hydroxide solution and regenerated into an OH type. This nonwoven fabric was a strongly basic anion exchange nonwoven fabric having a neutral salt decomposition capacity of 2.38 mg / g.

This non-woven fabric was punched out to 20φ, dried in a vacuum and N ₂ atmosphere so as not to come into contact with air, filled in the apparatus of Example 1, and subjected to a carbon dioxide (CO ₂ ) removal test.
The CO ₂ in the fluorine bag was diluted with pure air to 130 ppm. After the start of the removal test, CO _{2 at} the filter outlet showed 0 ppm, and the CO ₂ concentration in the bag dropped to 1 ppm or less in 50 minutes.

Example 7 (Removal of H ₂ S Hydrogen Sulfide) The same non-woven fabric as in Example 6 was filled in the apparatus of Example 1 and a hydrogen sulfide (H ₂ S) removal test was conducted. In addition, H ₂ S concentration
₂ was adjusted to 3 ppm with pure air. After the removal test was started, the H ₂ S concentration at the filter outlet was 0.0 ppm, and the H ₂ S concentration in the fluorine bag was reduced from the initial 3 ppm to less than 1 ppm in about 30 minutes.

Example 8 (Removal of NO ₃ ) Using the weakly basic anion exchange nonwoven fabric used in Example 5 and the apparatus of Example 1, a NO ₃ gas removal test was conducted.
The NO ₃ concentration in the fluorine bag was adjusted to 2 ppm with pure air. NO in the fluorine bag after the removal test started
_The concentration of ₃ decreased to 0.5 ppm or less in 30 minutes.

Example 9 (Removal of HF Hydrogen Fluoride) Using the weakly basic anion exchange nonwoven fabric used in Example 5 and the apparatus of Example 1, a hydrogen fluoride gas (HF) removal test was conducted. The HF concentration in the fluorine bag was 5 ppm, but decreased to 1 ppm or less 30 minutes after the start of the removal test. The HF concentration at the filter outlet was 0.5 ppm or less.

[0070]

EFFECTS OF THE INVENTION According to the present invention, a separation functional fiber in which functional groups are densely introduced on the fiber surface, physical and chemical deterioration is small, and strength can be sufficiently retained is obtained. Also,
This separation functional fiber has an excellent separation function and can perform gas separation or heavy metal separation from a liquid in a short time, so that it can be used as a gas removal filter, a heavy metal adsorbent, or the like.

Further, since the ion-exchange fiber is recyclable, a filter is made by using all the constituent components including the filter frame and the separator that are not violated by the regenerator, so that it can be regenerated with the regenerator after use. It is possible to use an ion exchange gas removal filter.

The above-mentioned concrete example is
The general characteristics of the invention are fully demonstrated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a fiber having a core-sheath structure of the present invention.

FIG. 2 is a schematic configuration diagram of a gas adsorption experimental apparatus used in Examples.

FIG. 3 is a graph showing the change over time in the ammonia concentration in the bag of Example 1.

FIG. 4 is a graph showing changes over time in the ammonia concentration in the bag of Example 2.

FIG. 5 is a graph showing changes with time of copper concentration in Example 3.

FIG. 6 is a graph showing a radiation irradiation dose and a reduction rate of tensile strength.

FIG. 7 shows a process of graft-polymerizing a sheath portion of a fiber having a core-sheath structure, and then, when a functional group is introduced, the dimensions of the core portion and the sheath portion increase and the sheath portion peels from the core portion. FIG.

FIG. 8 is a view showing a cross-sectional photograph of a composite fiber of a core part (PET) and a sheath part (PE) before grafting.

FIG. 9 is a view showing a cross-sectional photograph of the composite fiber of the core (PET) and the sheath (PE) after grafting.

FIG. 10: Sulfonated core after grafting (PE
The figure which shows the cross-section photograph of the composite fiber of T) and a sheath part (PE).

FIG. 11: Core part aminated after grafting (PE
The figure which shows the cross-section photograph of the composite fiber of T) and a sheath part (PE).

[Explanation of symbols]

1: core, 2: sheath, 3 fluororesin bag, 4: glass column, 5: non-woven fiber, 6: pump, 7, 8, 9: sampling unit, 10: flow meter

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[Procedure amendment]

[Submission date] August 30, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a fiber having a core-sheath structure of the present invention.

FIG. 2 is a schematic configuration diagram of a gas adsorption experimental apparatus used in Examples.

FIG. 3 is a graph showing the change over time in the ammonia concentration in the bag of Example 1.

FIG. 4 is a graph showing changes over time in the ammonia concentration in the bag of Example 2.

FIG. 5 is a graph showing changes with time of copper concentration in Example 3.

FIG. 6 is a graph showing a radiation irradiation dose and a reduction rate of tensile strength.

FIG. 7: Graft polymerization is performed on the sheath portion of a fiber having a core-sheath structure, and when a functional group is introduced next, the dimension between the core portion and the sheath portion increases and the sheath portion separates from the core portion. The figure which shows a process.

FIG. 8: Core part (PET) and sheath part (PE) before grafting
Of a cross section of a composite fiber having

FIG. 9: Core part (PET) and sheath part (PE) after grafting
Of a cross section of a composite fiber having

FIG. 10: Sulfonated core (PET) after grafting
And a cross-sectional photograph of a composite fiber having a sheath portion (PE).

FIG. 11 is a cross-sectional photograph of a composite fiber having a core portion (PET) and a sheath portion (PE) that are aminated after grafting.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location D01D 5/34 // D03D 1/00 Z (72) Inventor Hiroyuki Shima Asahi-machi, Ota-ku, Tokyo No. 11-1 EBARA CORPORATION (72) Inventor Kunio Fujiwara 4-2-1 Honfujisawa, Fujisawa City, Kanagawa Prefecture EBARA Research Institute

Claims (20)

[Claims] 1. A method for producing a separation-functional fiber, which comprises irradiating a fiber having a core-sheath structure composed of different polymers with ionizing radiation and then grafting a polymerizable monomer on the fiber. 2. The method for producing a separation-functional fiber according to claim 1, wherein the polymerizable monomer is glycidyl methacrylate. 3. The fiber having a core-sheath structure is a polymer whose sheath portion is capable of generating radicals upon irradiation with ionizing radiation, and whose core portion is capable of generating radicals and / or high radicals upon irradiation with ionizing radiation. The method for producing a separation-functional fiber according to claim 1, wherein the polymer is a polymer that is unlikely to cause molecular collapse. 4. The method for producing a separation-functional fiber according to claim 3, wherein the sheath portion is polyolefin and the core portion is polyester. 5. The method for producing a separation-functional fiber according to claim 1, wherein the fiber having the core-sheath structure has a sheath / core weight ratio in the range of 0.1 to 10. 6. The method for producing a separation-functional fiber according to claim 1, wherein during the graft polymerization, at least a part of the interface between the core portion and the sheath portion is separated in the fiber having the core-sheath structure. 7. The fiber having the core-sheath structure is a single fiber,
The method for producing a separation functional fiber according to any one of claims 1 to 6, which is selected from a woven fabric or a non-woven fabric, or a processed product of the single fiber, the woven fabric or a non-woven fabric. 8. A fiber having a core-sheath structure is composed of polymer components having different cores and sheaths, and an ion exchange group is introduced into the sheath of the fiber through radiation graft polymerization of a monomer other than styrene. Ion exchange fiber produced by 9. The ion exchange fiber according to claim 8, wherein glycidyl methacrylate is grafted by the radiation graft polymerization, and then ion exchange groups are introduced into the glycidyl methacrylate. 10. The ion exchange fiber according to claim 8, wherein the sheath portion is polyolefin and the core portion is polyester. 11. The ion exchange fiber according to claim 8, wherein the core-sheath portions are separated from each other at least at a part of the interface. 12. The shape of a monofilament, a woven fabric or a non-woven fabric, a porous processed product of the monofilament, a woven fabric or a non-woven fabric, or a non-porous processed product of the monofilament, a woven fabric or a non-woven fabric. The ion exchange fiber described. 13. The ion exchange fiber according to claim 12, wherein the sheath portions of adjacent fibers are fused to each other. 14. The ion exchange fiber according to claim 8, wherein the constituent component of the fiber having the core-sheath structure is polyethylene as the sheath component and polyethylene terephthalate as the core component. 15. The core-sheath, wherein the sheath part is a component that easily generates radicals upon irradiation with ionizing radiation, and the core part is a component that does not easily generate radicals and / or polymer collapse upon irradiation of ionizing radiation. A gas adsorbent produced by irradiating fibers having a structure with ionizing radiation and then grafting a polymerizable monomer on the sheath. 16. The gas adsorbent according to claim 15, wherein the polymerized monomer is glycidyl methacrylate. 17. The gas adsorbent according to claim 15, wherein the sheath portion is polyolefin and the core portion is polyester. 18. The gas adsorbent according to claim 15, wherein the fiber having the core-sheath structure has a sheath / core weight ratio in the range of 0.1-10. 19. The gas adsorbent according to claim 15, wherein the cross-sectional shape of the fiber having the core-sheath structure is a single core, and the core and the sheath are arranged concentrically or eccentrically. 20. The fiber having the core-sheath structure is selected from a single fiber or a processed product thereof, a woven or non-woven fabric which is an aggregate of single fibers, or a processed product of the woven or non-woven fabric. The gas adsorbent according to claim 15, characterized in that.