JP4395599B2 - Radiation graft polymerization substrate and filter material - Google Patents

Description

  The present invention relates to a base material for radiation graft polymerization composed of polymer fibers, particularly polyethylene fibers, and a radiation graft material obtained by introducing functional functional groups into the base material using radiation graft polymerization. The present invention also relates to improvements in the radiation graft polymerization process for woven or nonwoven substrates.

  In the radiation graft polymerization method, a polymer substrate is irradiated with radiation to form radicals, and a polymerizable monomer is grafted to the radical portion. Has recently been attracting attention as a method for producing a separation functional material. In particular, as a method of manufacturing chemical filter materials for air cleaning and ion exchange filter materials used in pure water manufacturing equipment that have recently been used for clean air in the precision electronics industry such as the semiconductor industry and pharmaceutical manufacturing industry. Radiation graft polymerization has attracted attention.

  As a polymer base material for radiation graft polymerization, a polyolefin-based polymer material is considered to be suitable, and among them, polyethylene is considered to be an optimum material for radiation graft polymerization. This is because polyethylene is more easily crosslinked and less likely to collapse when exposed to radiation than other polyolefin-based materials. Films and hollow fibers are well known as base materials for radiation graft polymerization using polyethylene, and they are used as ion exchange membranes, battery membranes, air purification materials, affinity separation membranes, water treatment materials, deodorizers, etc. It has been. For example, production of a battery membrane using a radiation-grafted polymer film is disclosed in Yuasa Jiho, 54, 57-62 (1983) “Grafted membrane by radiation pre-irradiation method”. Furthermore, the use of a polymer molded body as a water treatment material is disclosed in JP-A Nos. 5-1111685 and 5-1111637.

  On the other hand, it is widely practiced to form a woven or non-woven fabric from polymer fibers such as polyolefin and polyester, and to use this as a filter material. A filter material that is an aggregate of fibers such as woven or non-woven fabric. As far as the present inventor knows, practical examples in which polyethylene monofilament is used as a raw material for the production are few. This is because polyethylene's monofilament itself is a filter material because the physical and chemical properties such as melting point and chemical resistance of polyethylene are inferior to polypropylene, which is a typical example of other polyolefin materials. This is because it has not received much attention. In fact, polyethylene single fibers have excellent properties for radiation graft polymerization, but by constituting a woven or non-woven fabric from polyethylene single fibers and introducing functional functional groups thereto using radiation graft polymerization, Even if a radiation-grafted polymer woven or non-woven material is manufactured, its physical strength is not sufficient and “sag” occurs, so that the strength and shape stability as a filter material cannot be obtained. There was a problem that it was difficult to form the filter and the pressure loss of the resulting filter was high.

  As a method for solving such problems, the present inventors have proposed to produce a fiber having excellent separation functionality by applying radiation graft polymerization to the core / sheath composite fiber (Japanese Patent Laid-Open No. Hei 8-). (199480). The separation functional fiber proposed in this patent application is a non-woven fabric because a composite fiber using a high melting point polymer such as polyethylene as a sheath material and polypropylene or polyethylene terephthalate as a core material is used as a graft substrate. The heat fusion method can be adopted at the stage of the conversion, and the physical strength of the fiber and the bonding strength at the contact point of each fiber are taken into account. .

  However, in this composite fiber, since graft polymerization mainly occurs in the polyethylene of the sheath material, the sheath portion after the graft polymerization sometimes peels off from the core material, and a gap is formed between the core material and the sheath material. In some cases, the drug remains on the surface, resulting in deterioration of cleaning characteristics in the manufacturing process. Further, when trying to increase the graft ratio of the composite fiber as a whole, the graft ratio of the sheath portion becomes extremely high, so that a phenomenon that the sheath portion collapses is rarely observed.

  The present inventors have conducted intensive research to increase the strength of the formed radiation graft material when a radiation graft polymerization treatment is performed on a woven or non-woven base material composed of polyethylene single fibers to form a radiation graft material. It was. As a result, by combining a woven or non-woven base material composed of polyethylene monofilament with a polymer reinforcing material having higher strength and slower graft polymerization rate than the polyethylene monofilament, It has been found that a filter material having an excellent function and strength can be obtained by increasing the mechanical strength and applying radiation graft polymerization thereto, and further exhibiting an unexpectedly excellent effect as described below.

  That is, the first aspect of the present invention is a woven fabric or non-woven fabric composed of polyethylene fibers, and a woven fabric characterized by comprising a polymer reinforcing material having a higher strength and a slower graft polymerization rate than the polyethylene fibers. The present invention relates to a base material for radiation graft polymerization in the form of a cloth or a nonwoven fabric.

  The present invention also relates to a filter material characterized in that a functional functional group is introduced into the radiation graft polymerization base material according to the above-described embodiment using radiation graft polymerization.

  The unexpected effects of the radiation graft polymerization base material according to the first aspect of the present invention will be described below. When a woven or non-woven fabric that is an aggregate of fibers is used as a filter material for gas and liquid, it is often performed to form a filter by forming the filter material into a pleated shape in order to reduce pressure loss. . In this case, in order to keep the distance between the filter materials in the flat part between the peak part and the peak part, the valley part and the valley part, and the peak part and the valley part of the pleats folded from the nonwoven fabric, insert a spacer. Is common. A spacer made of metal or plastic is often used as the spacer. As the shape of the spacer, a shape in which irregularities are regularly arranged is often adopted in order to maintain a constant interval between the filter materials including a corrugated shape.

  In the case of a chemical filter, it is very important to make the surface wind speed of a woven fabric or a non-woven fabric uniform. This is because a conventional filter for removing fine particles has a large flow rate of fluid in a high flow rate portion and traps many fine particles even if the flow rate is non-uniform. Since the flow becomes larger and the flow is directed to the part where the pressure loss is small, the flow rate is naturally uniformed. In the case of a chemical filter, the substance to be removed is a gas component. This is because the pressure loss does not increase. Therefore, in chemical filters, the latest attention has been paid to the design of spacers for keeping the surface wind speed constant.

As a result, the unevenness | corrugation for keeping the space | interval of a woven fabric or a nonwoven fabric constant must be increased. However, when the uneven portion of the spacer comes into contact with the woven or non-woven fabric, the contact of air to that portion is hindered, so the effective filtration area of the filter is reduced. In extreme cases, the ineffective filtration area sometimes exceeded 20% of the total area of the woven or non-woven fabric. Considering this problem, in forming a pleated filter, a large amount of woven fabric or non-woven fabric is often folded in advance, resulting in an increase in cost. The same problem applies not only to pleated filters but also to parallel flow filters.

  When radiation graft polymerization is applied to a woven or non-woven fabric composed of polymer fibers, dimensional changes in the thickness direction, the longitudinal direction, and the transverse direction occur. Here, since the base material according to the present invention combines a woven or non-woven fabric composed of polyethylene fibers with a polymer reinforcing material having a strength higher than that of the polyethylene fibers and a slow graft polymerization rate, the fiber portion and the reinforcement are combined. Graft polymerization proceeds at a different rate from the material part, thus causing dimensional changes at different rates. As a result, the base material after the graft polymerization has a rough surface.

  For example, a polyethylene net with a larger wire diameter (that is, higher strength and slower graft polymerization rate than polyethylene constituting the nonwoven fabric base) is fused as a polymer reinforcing material to a nonwoven fabric base composed of polyethylene. When radiation graft polymerization is performed on the base material, the base material after polymerization has undulations on the surface as shown in FIG. In addition, in FIG. 1, 10 shows a fiber nonwoven fabric material and 11 shows a net material.

  In the examples described later, a base material (Example 1) in which 100 d (denier) polyethylene filaments are woven vertically and horizontally into a non-woven base material composed of polyethylene fibers, and the fibers on both sides of the polyethylene non-woven base material. A base material (Example 2) in which a polyethylene net having a larger diameter is fused is manufactured and subjected to radiation graft polymerization. The shape of the surface of the base material before and after the radiation graft polymerization is shown in FIG. 3 and FIG. 4 / FIG. 5 (micrographs). Also from these photographs, it is clearly shown that undulations are formed on the surface when graft polymerization is applied to the substrate according to the present invention.

  Thus, since the graft material obtained by graft polymerization on the nonwoven fabric substrate of the present invention has undulations on the surface, when this is folded into a pleat shape, without using a spacer, between the materials Pleats are formed with a constant spacing. Therefore, when an ion exchange chemical filter is manufactured by processing the graft material manufactured according to the present invention into a pleat shape, the intervals between the flat portions between the peaks and the peaks, the valleys and the valleys, and the peaks and the valleys can be obtained without using a spacer. It is kept constant, the flow rate becomes uniform, and the ion exchange capacity of the entire filter is efficiently consumed. Further, since the work of inserting the spacer is unnecessary, the work can be simplified and the cost can be reduced. Furthermore, although the grafting is carried out in the reinforcing material portion even though the graft rate is small, both the nonwoven fabric base material portion and the reinforcing material portion have ion exchange groups, so that the entire material The gas adsorption capacity becomes larger and the service life becomes longer. Further, by devising the joining between the reinforcing material and the polyethylene fiber, it becomes possible to suppress the release of the fiber pieces from the woven / nonwoven fabric.

In the present invention, the polyethylene single fiber constituting the woven or non-woven fabric is usually preferably from several denier to several tens of denier.
In addition, as a polymer reinforcing material that functions as a reinforcing material for woven or non-woven fabrics and has a higher strength than that of polyethylene single fibers of woven or non-woven fabrics and has a slow rate of radiation graft polymerization, a polyethylene yarn or thread-like material that is thicker than polyethylene single fibers In addition, those processed products, for example, a net, a sheet-like material such as a polyethylene film, and a material obtained by tearing or perforating the sheet-like material can be used. Since these have a larger wire diameter and a smaller surface area per unit weight than a woven or non-woven polyethylene single fiber, the rate of radiation graft polymerization is low.

Usually, it is known that when a polymer material is subjected to radiation graft polymerization, the physical strength of the material decreases. However, the polyethylene reinforcing material according to the present invention described above has a larger wire diameter compared to the polyethylene single fiber constituting the woven / nonwoven fabric, so that the surface of the polyethylene reinforcing material is not changed even after the radiation graft polymerization reaction is completed. However, radiation graft polymerization has not progressed, and therefore its physical strength is not greatly impaired. Therefore, in the polyethylene material according to the present invention, by combining such a reinforcing material, the physical strength is maintained without being greatly reduced after the radiation graft polymerization.

  As a method of using polyethylene having various shapes as a reinforcing material and processing it into a reinforced woven / nonwoven fabric material by combining with polyethylene monofilament, polyethylene is used when the reinforcing material is a polyethylene thread or a filamentous material. A method of knitting the yarn or thread into a woven / nonwoven fabric composed of single fibers is convenient. Further, when the reinforcing material is a polyethylene film or a net-like material, a method of adhering to the surface of the polyethylene woven fabric / nonwoven fabric is convenient, and as the adhering method, heat fusion is preferable. Further, a method of forming a nonwoven fabric material by entwining polyethylene single fibers with a net or the like can also be employed.

  As a method for producing a woven / nonwoven fabric composed of polyethylene single fibers, various methods known in the art can be used, such as needle punching or embossing such as spot welding. As described above, it is preferable to employ various methods for preventing the fiber aggregates from being dispersed.

  In addition, although the above description is mainly related to forming a woven or non-woven fabric from a single polyethylene fiber and combining it with a polyethylene reinforcing material, the idea of the present invention can be applied to other polymer materials. Can do. That is, polymer fibers other than polyethylene fibers can be used as the fibers constituting the woven or non-woven fabric, and / or the polymer having a higher strength and slower graft polymerization rate than the fibers constituting the woven or non-woven fabric as the reinforcing material. Materials can be combined. When such a graft polymerization base material is subjected to radiation graft polymerization, the graft ratio of the woven / nonwoven fabric material portion and the reinforcement material portion are different from each other, and thus the dimensional change is different, as in the polyethylene material described above. As a result, the base material after the graft polymerization similarly has undulations, and can be formed into a pleated shape without using a separator. In addition, since the graft polymerization rate of the reinforcing material is low, its strength is not greatly impaired, and thereby the physical strength of the base material is maintained.

  That is, the second aspect of the present invention is characterized in that it is composed of a woven or non-woven fabric composed of polymer fibers and a polymer reinforcing material having a strength higher than that of the polymer fibers and a slow rate of radiation graft polymerization. The present invention relates to a woven or non-woven polymer substrate for radiation graft polymerization.

  As a material that can be used in the second aspect of the present invention, halogenated polyolefins such as vinyl chloride and vinyl fluoride can be used as the polymer fibers constituting the woven or non-woven fabric. Further, as the polymer material constituting the reinforcing material, halogenated polyolefins, polyethylene terephthalate, polyurethane fibers, vinylon fibers, cellulose fibers, glass fibers, and other inorganic fibers can be used.

  In the above embodiment of the present invention, the height of the undulations formed after graft polymerization is performed on the graft polymerization base material (that is, the interval between pleats when formed into a pleat shape), the number, etc. It can be controlled by adjusting the graft ratio of the fiber substrate, the shape of the reinforcing material, the basis weight, the thickness, and the like.

Also, when forming a woven or non-woven fabric substrate from polymer fibers, other polymer fibers having a radiation graft polymerization rate slower than that of the polymer fibers are used in combination, and the polymer fibers and the other polymer fibers are mixed. Thus, the strength of the woven fabric or nonwoven fabric substrate after radiation graft polymerization can also be increased by forming the woven fabric or nonwoven fabric substrate. For example, polyethylene fibers and polyethylene terephthalate fibers (known to hardly react even when subjected to radiation grafting) are mixed at a ratio of about 80:20 to form a nonwoven fabric to form a base material for radiation graft polymerization. Obtainable. In such a radiation graft polymerization base material, polyethylene fibers and polyethylene terephthalate fibers are randomly entangled. When subjected to a radiation graft polymerization reaction, only the polyethylene fibers of the randomly entangled fibers undergo a graft reaction. The polyethylene terephthalate fiber remains almost unreacted. Therefore, the strength of the nonwoven fabric substrate is maintained by the polyethylene terephthalate fiber in which no graft reaction has occurred. However, in this case, since the polyethylene fibers and the polyethylene terephthalate fibers are arranged randomly, that is, uniformly, the undulations are hardly formed after the radiation graft polymerization reaction, and in the case of using in a pleated shape It is necessary to use a spacer as usual.

  That is, the third aspect of the present invention is a woven fabric or nonwoven fabric characterized in that a polymer fiber and another polymer fiber having a radiation graft polymerization rate slower than that of the polymer fiber are mixed to form a woven fabric or a nonwoven fabric. The present invention relates to a nonwoven fabric-like polymer substrate for radiation graft polymerization.

  As a material that can be used in the third aspect of the present invention, polyethylene or halogenated polyolefins such as vinyl chloride and vinyl fluoride can be used as the polymer fiber. Further, as other polymer fibers having a radiation graft polymerization rate slower than that of the polymer fibers, inorganic fibers such as halogenated polyolefins, polyethylene terephthalate, polyurethane fibers, vinylon fibers, cellulose fibers, and glass fibers can be used. . Also, as other polymer fibers, two or more of these fibers can be used in combination.

  In addition, as another technique for increasing the strength of a radiation graft material formed from a base material composed of a polyethylene monofilament woven or non-woven fabric, the present inventors have made a woven or non-woven fabric base composed of polyethylene monofilament. When carrying out the radiation graft polymerization treatment on the material, the graft reaction is limited to the surface portion of the fiber, and the central portion of the fiber is left in the non-grafted state. It has been found that a radiation-grafted woven or nonwoven material having a high physical strength can be provided.

  That is, the fourth aspect of the present invention is a woven or non-woven material composed of polyethylene monofilament, wherein only the surface portion of the fiber is subjected to radiation graft polymerization, and the center portion of the fiber is in an ungrafted state. The present invention relates to a radiation graft processing material.

  In general, radiation graft polymerization is performed in order to introduce functional functional groups such as ion exchange groups into a base material, so that from the viewpoint of increasing the functional group density of the base material by introducing as many functional functional groups as possible. The fact that it is desirable to carry out the graft polymerization deep inside the substrate is a matter generally considered in the art. However, it is known that when a polymer material is subjected to a radiation graft polymerization treatment, the physical strength of the material decreases. In particular, when a hydrophilic group typified by an ion exchange group or the like is introduced into a substrate through radiation graft polymerization, water is attracted around the ion exchange group, so that the physical strength of the substrate is increased by the grafting. It is greatly reduced compared to the previous one.

In the radiation graft material according to the fourth aspect of the present invention, the center portion of the fiber cross section is not grafted, and the graft polymerization is performed only on the surface portion. The strength retains the value before grafting. Therefore, it is possible to obtain a fiber material into which a functional functional group has been introduced through radiation graft polymerization without significantly impairing the physical strength of the entire fiber. That is, in the radiation grafted material according to the fourth aspect of the present invention, the non-grafted portion at the center of the fiber introduces a physical strength maintaining function, and the grafted portion of the surface portion of the fiber is introduced by graft polymerization. It performs additional functions such as ion exchange function.

  Thus, in the fourth aspect of the present invention, the maintenance of physical strength, which has not been considered in the conventional radiation grafting treatment, is achieved. Therefore, due to problems such as fiber strength and sag, the radiation grafting is performed. By using a woven fabric or a nonwoven fabric substrate composed of polyethylene single fibers that could not be used conventionally as a polymerization substrate, a radiation-grafted material showing excellent physical strength and a high graft rate can be obtained.

  In the fourth aspect of the present invention, “only the surface portion of the fiber is subjected to the radiation graft polymerization treatment” means that the entire cross section of the fiber is not grafted and a non-grafted portion remains in the central portion of the fiber cross section. Means that When the proportion of the non-grafted portion is large, the strength of the graft-treated fiber material is high, but the graft rate is low. Conversely, when the proportion of the non-grafted portion is small, a high graft ratio is achieved, but the strength of the graft-treated fiber material is lowered. The depth of the grafted portion is determined by a balance between a desired graft ratio and the strength of the material depending on the use of the material. Usually, a fiber material grafted from the surface of the fiber cross section to a depth of 2/3 to 1/3 is preferable in terms of balance between strength retention and achievement of a high graft ratio.

  Grafting is performed only on the surface portion of the fiber substrate, and the radiation graft polymerization reaction proceeds so that the non-grafted portion remains in the central portion and the depth of the graft portion is determined by the type, size, and size of the fiber substrate. A person skilled in the art can empirically select various parameters such as the irradiation method, irradiation intensity, time, graft polymerization reaction method, and graft polymerization reaction conditions as appropriate.

  Polyethylene is classified into low-density polyethylene and high-density polyethylene depending on the production method. Low density polyethylene has a small degree of crystallinity of 50 to 60% and a large number of amorphous parts. Therefore, the monomer diffusion rate is high during the grafting reaction, and graft polymerization easily occurs inside the fiber. In contrast, high density polyethylene has a specific gravity greater than 0.94, a high degree of crystallinity of 80 to 90%, and a small amount of amorphous parts, so that the graft reaction is relatively stopped near the fiber surface. Convenient to. Furthermore, since high density polyethylene has many radicals generated in the crystal, that is, radicals that can be used in the grafting reaction, and has the advantage that the strength after graft polymerization is high and the ultimate graft ratio is high, the present invention has the advantages. It is excellent as a base material for producing such a radiation graft processing material.

  The technical idea according to the fourth aspect of the present invention can be applied not only to a material based on a woven or non-woven fabric composed of polyethylene single fibers but also to other polymer materials. That is, the fifth aspect of the present invention is a woven or non-woven material composed of a single polymer fiber, wherein only the surface portion of the fiber is subjected to radiation graft polymerization, and the center portion of the fiber is in a non-grafted state. The present invention relates to a radiation graft processing material. Examples of the fiber base material constituting the woven or nonwoven material that can be used in the fifth aspect of the present invention include halogenated polyolefins such as vinyl chloride and vinyl fluoride in addition to polyethylene.

  As a method of performing radiation graft polymerization on the base material for graft polymerization according to the present invention, a pre-irradiation graft polymerization method in which a radical is formed by previously irradiating the base material and then a polymerizable monomer (monomer) is contacted. And a simultaneous irradiation graft polymerization method in which the substrate is irradiated with radiation in the presence of a monomer, and any method can be employed in the present invention.

Further, the graft polymerization method is classified into the following methods depending on the manner of contact between the monomer and the substrate.
A method of graft polymerization while immersing the irradiated base material in a monomer solution is called liquid phase graft polymerization. In this case, a reaction temperature of 20 to 60 ° C. and a reaction time of 2 to 10 hours are suitable. The liquid phase graft polymerization method can uniformly perform graft polymerization, but has a problem of consuming a large amount of drug.

  The method of bringing the irradiated substrate into contact with the monomer vapor is called gas phase graft polymerization, which can be applied only to monomers with a relatively high vapor pressure and tends to cause uneven grafting, but the amount of waste liquid generated is small and after graft polymerization. There is an advantage that the substrate is obtained in a dry state. In this case, the reaction temperature is preferably 20 to 80 ° C. and the reaction time is 2 to 10 hours.

Any of the above polymerization methods can be applied to the present invention.
In addition, a method of applying a predetermined amount of monomer to an irradiated base material and performing graft polymerization by reacting in a vacuum or in an inert gas is referred to as impregnation graft polymerization, and in this case, a reaction temperature of 20 to 60 ° C, A reaction time of 0.2 to 8 hours is preferred. In this impregnation graft polymerization method, since almost all of the used monomers are reacted, the residual amount of unreacted drug is small and economical, and the base material after graft polymerization is obtained in a dry state. Is easy to handle and has a small amount of waste liquid. This method is extremely effective when a porous material such as woven / nonwoven fabric is used as the graft substrate.

  The impregnation graft polymerization method is very effective for use in the fourth and fifth aspects of the present invention for the following reasons. In radiation graft polymerization, an irradiated base material having radicals and a monomer are brought into contact with each other to undergo a polymerization reaction, but as the polymerization reaction proceeds, radicals move from the irradiated base material to the monomer, and the monomer itself undergoes polymerization. The phenomenon of starting occurs. For this reason, the molecular weight of the monomer increases with the second half of the reaction, and it becomes difficult for the monomer to impregnate / penetrate into the fiber base material, so that the graft reaction is easily stopped at the surface portion of the fiber base material. It is. On the other hand, in the case of liquid phase graft polymerization, the amount of monomer is overwhelmingly larger than that of the base material, so the proportion of unpolymerized monomer is large even in the latter half of the reaction, and these unpolymerized monomers diffuse and penetrate into the fiber. Therefore, in order to obtain a graft-treated material in which only the surface portion of the fiber according to the fourth and fifth aspects of the present invention is subjected to the radiation graft polymerization treatment, conditions such as graft reaction time and reaction temperature are reliably controlled. There is a need.

The polyethylene single fibers constituting the woven fabric or the nonwoven fabric substrate used in the present invention are usually preferably those having a thickness of several deniers to several tens of deniers.
As a method for producing a woven / nonwoven fabric used as a graft base material in the present invention, various methods known in the art can be used, but needle punching or embossing such as spot welding is performed. As described above, it is preferable to employ a method of applying various ideas so as not to disperse the fiber aggregate.

  The polymerizable monomer introduced into the substrate by radiation graft polymerization is itself a polymerizable monomer having various functional functional groups, or functions by further performing a secondary reaction after grafting it. A polymerizable monomer capable of introducing a functional functional group can be used.

  For example, when producing an ion exchange filter material according to the present invention, examples of monomers having ion exchange groups include acrylic acid, methacrylic acid, sodium styrenesulfonate, sodium methallylsulfonate, sodium allylsulfonate, vinylbenzyltrimethylammonium chloride, and the like. By carrying out radiation graft polymerization using, a functional functional group can be directly introduced into the fiber substrate to obtain an ion exchange filter material.

  Examples of the monomer that can further introduce an ion exchange group by performing a secondary reaction after radiation graft polymerization include acrylonitrile, acrolein, vinylpyridine, styrene, chloromethylstyrene, and glycidyl methacrylate. For example, ion exchange fibers can be obtained by introducing glycidyl methacrylate into a nonwoven fabric substrate by radiation grafting and then introducing a sulfone group by reacting a sulfonating agent such as sodium sulfite. In addition, ion exchange groups such as quaternary ammonium and tertiary amino groups can be introduced by diethanolamine or the like through glycidyl methacrylate.

  As an application example of the present invention, there is mainly a method for obtaining an ion exchange filter material. However, the present invention can also be applied to a heavy metal adsorbent having a chelate group, a catalyst, a carrier for affinity chromatography, and the like. Can do.

  Note that the first to third aspects of the present invention described above can be combined with the fourth and fifth aspects. That is, a polymer substrate for radiation graft polymerization in the form of a woven fabric or a nonwoven fabric composed of a woven fabric or a nonwoven fabric composed of polymer fibers and a polymer reinforcing material having a strength higher than that of the polymer fibers and a low rate of radiation graft polymerization, Alternatively, a polymer group for radiation graft polymerization in the form of a woven or non-woven fabric, wherein a polymer fiber and another polymer fiber having a slower radiation graft polymerization rate than the polymer fiber are mixed to form a woven or non-woven fabric. The material is subjected to a radiation graft polymerization reaction on the base material, and at that time, only the surface portion of the polymer fiber is subjected to the radiation graft polymerization treatment, thereby obtaining a radiation grafted material having excellent strength. be able to.

The inventors have also found a very effective method of performing radiation graft polymerization on woven or non-woven materials. This will be described in detail below.
As described above, the radiation graft polymerization method can be classified into a simultaneous irradiation graft polymerization method and a pre-irradiation graft polymerization method. Any of the polymerization methods can be put into practical use, but the pre-irradiation graft polymerization method has a small amount of homopolymer produced by polymerization of the monomer itself. For example, pure water is used for water treatment. As a material for production and gas treatment, it is suitable as a method for producing a material for air purification or clean air production.

The pre-irradiation graft polymerization method is classified into a liquid phase graft polymerization method and a gas phase graft polymerization method depending on whether the monomer brought into contact with the irradiated substrate is liquid or gas.
The gas phase graft polymerization method is economical because it uses a small amount of monomer, but can be applied only to a monomer having a high vapor pressure, and has a problem that uneven grafting tends to occur in the product. . On the other hand, since the liquid phase graft polymerization method can be applied to a wide range of monomers, it is highly versatile.

  However, when pre-irradiation liquid phase graft polymerization is applied to a substrate with a large number of voids such as woven fabric or nonwoven fabric, it enters into the voids in the substrate at the time of radiation irradiation or graft polymerization reaction. If the oxygen is not sufficiently removed, it is difficult to perform uniform graft polymerization at a high graft rate, which causes a problem in the physical stability of the product after the graft polymerization. Furthermore, after the graft polymerization, a large amount of cleaning liquid is required for cleaning unnecessary monomers that have entered the voids of the base material, and the waste liquid treatment is very expensive.

As a method for solving such problems, the present inventors have proposed a new graft polymerization method in Japanese Patent No. 1933644.
This method separates the irradiation and the graft polymerization reaction, impregnates a pre-irradiated substrate with a predetermined amount of monomer liquid, and then reduces the residual oxygen by reducing the pressure. This is a radiation graft polymerization method in which a graft polymerization reaction is performed. In this method, the monomer liquid adhering to the base material becomes a monomer evaporation source for the gas phase grafting reaction, the product after grafting is finished in a dry state, and the graft ratio can be easily controlled. It was an epoch-making method that had the advantages of both phase graft polymerization and gas phase graft polymerization. Furthermore, since this method separates the radiation irradiation step and the graft polymerization reaction step, it is not necessary for the person who performs the graft polymerization reaction to own an irradiation source, which is suitable for small-scale production.

  However, this method has the following problems. The distribution of radicals generated in the base material upon irradiation is uniform in the base material, although it depends on the energy of the radiation. When the radiation irradiation and the graft polymerization reaction are carried out separately, the radicals in the amorphous part disappear, and only the radicals generated in the crystal are used for the graft polymerization reaction. Therefore, in order to obtain a low graft utilization efficiency and a sufficient graft ratio, a high dose had to be irradiated.

  In addition, if the time from radiation irradiation to graft polymerization reaction becomes longer, depending on the material of the storage container of the irradiated base material, oxygen contamination occurs from the storage container, resulting in a decrease in the number of radicals and alteration of the quality of the radicals. It is easy to happen. Furthermore, the stage of shifting from the storage process of irradiated base materials to the graft polymerization reaction requires manpower to take out the irradiated base materials from the storage container and to store and attach the extracted base materials to the reactor. In addition, since the substrate was exposed to the air during this stage, radical reduction and alteration were likely to occur.

  At the time of graft polymerization, the presence of oxygen further adversely affects the progress of the reaction than at the time of irradiation, so oxygen must be removed from the substrate once exposed to the air, In order to sufficiently remove the oxygen that entered, a decompression operation was necessary. Therefore, it is necessary to make the graft polymerization reaction vessel a sealed vessel according to the vacuum vessel, which has been a major factor that hinders the continuation of the processing steps.

Under such circumstances, there has been a long-awaited method capable of continuously subjecting a long woven or non-woven material to radiation graft polymerization in large quantities.
As a result of intensive studies to find a method for solving the above-mentioned problems, the present inventor continuously performed irradiation of an electron beam to the substrate, impregnation of the monomer to the irradiated substrate, and graft polymerization reaction in a nitrogen atmosphere. It has been found that radiation graft polymerization can be carried out efficiently particularly for long woven / nonwoven fabric materials. That is, the sixth aspect of the present invention is a first step of irradiating an electron beam in a nitrogen atmosphere to a woven or non-woven base material that is an aggregate of fibers; the irradiated base material in a nitrogen atmosphere. A second step of contacting a predetermined amount of the monomer; a third step of graft polymerization of the contacted monomer and the substrate in a nitrogen atmosphere; and the first to third steps are continuously performed. The present invention relates to a radiation graft polymerization method for a long woven fabric or a nonwoven fabric substrate. If desired, it is preferable to perform a preliminary step of replacing air present in the base material with nitrogen gas before the first step.

  The radiation source used in the sixth aspect of the method of the present invention is preferably an electron beam. When using γ-rays, a woven or non-woven substrate wound in a roll is placed on an irradiation table and irradiated while cooling. The amount of the processed substrate is limited to several hundred meters. On the other hand, in the electron beam irradiation, since the radiation transmission power is small, but the dose rate is large, a method is adopted in which a woven or non-woven fabric is fed at a high speed from a roll and irradiated, and then wound around the roll again. be able to. Therefore, no problem arises even if the number of m of the base material is increased, which is suitable for mass production.

In the sixth aspect of the present invention, the electron beam irradiation conditions are preferably a voltage range of 100 keV to 500 keV, an electron beam current range of 3 mA to 50 mA, and an irradiation dose range of 30 kGy to 200 kGy. When the above parameters are within this range, radicals are uniformly generated on the front and back of a normal woven fabric or non-woven fabric, and the conveyance speed of the base material can be sufficiently large to enable mass production.

  In the method according to the sixth aspect of the present invention, since the radiation irradiation step and the graft polymerization reaction are continuous, the radical generated by the radiation irradiation can be used for the graft reaction before disappearing. Therefore, the necessary irradiation dose can be reduced to 1/4 to 1/7 of the conventional method.

  In the sixth aspect of the present invention, various means known in the art can be used as means for achieving a nitrogen atmosphere at the time of radiation irradiation, but there is a method of introducing liquid nitrogen into the system. It is preferable because removal of oxygen and prevention of temperature rise during irradiation can be achieved at the same time. Although the temperature of the base material at the time of electron beam irradiation depends on the shape of the base material and the time from the radiation irradiation to the graft polymerization reaction, it is generally preferably −50 ° C. to + 50 ° C. According to the method of the present invention, since the substrate irradiated with radiation is not exposed to air before graft polymerization, oxygen entering the substrate can be reduced as much as possible, and the graft polymerization reaction vessel is sealed. Since it is not necessary to reduce the pressure in the structure, the processing steps can be continued.

  In the method according to the sixth aspect of the present invention, it is necessary to remove oxygen present in the woven fabric or non-woven fabric substrate before performing radiation irradiation. It is preferable to provide a preliminary step for nitrogen substitution. For example, in the radiation irradiation step, oxygen in the base material can be removed by adopting a method such as blowing nitrogen on the base material. In this case, the nitrogen replacement preliminary step can be eliminated. In order to apply the method of the present invention to woven fabrics or nonwoven fabric substrates having various shapes, it is preferable to provide a preliminary step of nitrogen substitution.

  Nitrogen replacement can be achieved by operating the system under reduced pressure-introducing nitrogen. The frequency | count of pressure reduction-nitrogen introduction operation can be determined with the shape of the base material to process, the length of a base material, etc. The decompression operation in the nitrogen substitution preliminary step is preferably performed in a closed container, but it is not necessary to control the oxygen concentration as strictly as in the graft polymerization reaction, so that a constant decompression state can be maintained in the continuous apparatus. It is also sufficient to arrange possible chambers. By repeating the operation of reducing the pressure and introducing nitrogen several times, the oxygen concentration in the voids of the substrate can be easily reduced to a desired value or less. The degree of pressure reduction and the amount of nitrogen introduction necessary for sufficient nitrogen substitution in the method of the present invention vary greatly depending on the shape of the substrate, the material, the conveyance speed of the substrate, etc., but generally the system is 20-30 mmHg. After depressurizing to nitrogen, nitrogen substitution can be performed by introducing nitrogen to bring the system pressure to atmospheric pressure. When the oxygen concentration in the system is further lowered, this operation can be repeated 2 to 3 times.

  In the method according to the sixth aspect of the present invention, a second step of bringing the substrate into contact with a predetermined amount of monomer is provided between the radiation irradiation step and the graft polymerization reaction step. This step is for preliminarily applying the amount of monomer used for the graft polymerization reaction to the irradiated substrate. In this step, by removing excess monomer from the substrate in excess of the amount used for the graft polymerization reaction, the operation of removing the excess monomer from the substrate after the graft polymerization reaction can be eliminated. Further, in the conventional method in which the liquid phase graft polymerization is performed while the irradiated substrate is immersed in the monomer liquid, the graft ratio is controlled by the reaction temperature and the reaction time. By controlling the application amount, in addition to the control by the reaction temperature and the reaction time, the graft ratio can be controlled more stably.

As a method for bringing the substrate into contact with a predetermined amount of monomer, various methods known in the art can be adopted. For example, when a product with a longer lifetime is preferable, such as when a product is used as a chemical filter. The graft ratio is preferably large, and for this purpose, it is a simple method to impregnate the substrate into the monomer liquid. However, when the substrate is dipped in the monomer solution and the substrate is pulled up, the adhesion amount of the monomer solution becomes more than 5 times the weight of the substrate and dripping occurs. In the method of the present invention, in order to bring a predetermined amount of monomer into contact with the substrate, it is necessary to squeeze the excess monomer solution with a roll or the like. Of course, the excess monomer solution can be removed by other methods known in the art.

  The substrate provided with a predetermined amount of the monomer liquid is then subjected to a graft polymerization step. In the method of the present invention, the graft polymerization is performed by heating the substrate impregnated with the monomer to a graft polymerization temperature of 20 to 80 ° C. in a nitrogen atmosphere. At this time, although depending on the graft polymerization reaction temperature, it is desirable to maintain the oxygen concentration in the atmosphere at 1000 ppm or less in order to obtain a high graft ratio in a short time. The oxygen concentration, radiation irradiation dose, and graft polymerization reaction temperature can be adjusted as appropriate so as to achieve a predetermined reaction rate and ultimate graft rate. In the present invention, generally, the graft polymerization reaction is carried out by heating the substrate at a graft polymerization temperature within the above range for 5 minutes to 5 hours, preferably 5 minutes to 1 hour, most preferably 10 minutes to 30 minutes. To advance.

  FIG. 6 shows the concept of an apparatus for performing the method according to the sixth aspect of the present invention. The apparatus includes a nitrogen replacement tank 1 for replacing air existing in a woven or non-woven fabric substrate with nitrogen gas; electron beam irradiation for irradiating the woven or non-woven fabric substrate with an electron beam in a nitrogen atmosphere. Apparatus 3; a monomer impregnation tank 4 for bringing the irradiated base material into contact with the monomer in a nitrogen atmosphere; a graft polymerization tank 5 for graft polymerizing the contacted monomer and the base material in a nitrogen atmosphere; Each device is configured in series. Further, sheet material transfer means for pulling out the roll-shaped woven fabric or nonwoven fabric substrate 2 and continuously passing through each of the above-described apparatuses and winding it again in a roll shape after the graft polymerization treatment is completed, Located in each device. The sheet material transfer means includes a sheet drawing device 7, a sheet conveying roll 8, and a sheet winding device 9. As described above, the nitrogen replacement step can be omitted, and in this case, the nitrogen replacement tank 1 is not necessary.

  In the continuous processing apparatus for a long base material according to the present invention, the long base material is subjected to continuous processing in each step by transporting the long base material through the apparatus at an appropriate transport speed. Suitable transport speeds are generally in the range of 1-20 m / min, preferably 2-15 m / min, most preferably 2-10 m / min.

  Examples of the base material that can be subjected to radiation graft polymerization using the method according to the sixth aspect of the present invention include polyolefins such as polyethylene and polypropylene, and woven fabrics made of halogenated polyolefins such as polyvinyl chloride, Long materials such as non-woven fabrics and foams can be used.

In the method according to the sixth aspect of the present invention, a woven or non-woven long sheet material (long sheet material for radiation graft polymerization) subjected to radiation graft polymerization is used as it is as shown in FIG. In this case, unreacted portions are formed at the front end portion and the rear end portion of the long sheet material. That is, after attaching a long sheet material to the reaction apparatus shown in FIG. 6, when the reaction is performed while winding the long sheet material by the take-up roll 9 with each step as a reaction condition, Of the long sheet material attached to the part, the part existing in the previous region from the irradiation region 3 at the start of operation is wound around the roll 9 without performing all the steps of the radiation graft polymerization reaction. . In addition, when a plurality of rolls of sheet material are processed continuously, when the next roll is attached after the roll of one long sheet material is processed, If the reaction is resumed by joining the front end portion of the long sheet material, there will be no unreacted portion at the joining location, but if the processing of all rolls is completed and the reaction device is stopped, the sheet drawing device Since all the sheets of the last roll are drawn from 7 and all the sheet material is taken up by the take-up roll 9 after the reaction apparatus is stopped, the previous area from the polymerization reaction area 5 in the apparatus when the reaction is stopped. Also, the portion existing in the film is wound around the roll 9 without performing all the steps of the radiation graft polymerization reaction. In this way, there are portions where the radiation graft polymerization reaction is not performed at the front and rear ends of the long sheet material for radiation graft polymerization, so this portion is removed and used as a filter material, etc. There is a problem that the yield of the is reduced. For example, assuming that the length of the long roll sheet for radiation graft polymerization is 500 m and the stroke length in the reactor is 50 m, the front end 50 m of the first roll and the rear end 50 m of the last roll are unreacted. This part will not be used as a product.

  As a means for solving such a problem, it is conceivable to use a long conveying material (dummy sheet) having a length equivalent to or slightly larger than the stroke length of the reaction apparatus. For example, first, the dummy sheet is attached to the take-up roll 9 of the apparatus shown in FIG. 6 and the dummy sheet is transferred to the conveyance line in the apparatus so that the rear end is arranged in the nitrogen replacement tank 1. Next, the roll of the long sheet material for radiation graft polymerization is set in the sheet drawing device 7, and the leading end of the long sheet material for radiation graft polymerization and the rear end portion of the dummy sheet are joined in the nitrogen replacement tank 1. After that, each process of the apparatus is subjected to reaction conditions, and the dummy sheet is wound up by the winding roll 9 so that the long sheet material for radiation graft polymerization is sent out sequentially. If it does in this way, all the long sheet materials for radiation graft polymerization can be applied to the whole process of radiation graft polymerization reaction from the front end part. Further, if a dummy sheet is further bonded to the rear end portion of the long sheet material for radiation graft polymerization, after all the long sheet material for radiation graft polymerization is wound on the roll 9 through all the steps of the radiation graft polymerization reaction. The apparatus is stopped, and the wound long sheet material subjected to the radiation graft polymerization treatment is separated from the dummy sheet and taken out. Next, the front end of the dummy sheet left in the apparatus is attached to the take-up roll 9, and a small amount is taken up on the take-up roll 9 so that the rear end of the dummy sheet is placed in the nitrogen replacement tank 1. Then, after setting a new roll of radiation graft polymerization long sheet material in the drawer 7 and joining the rear end of the dummy sheet and the front end of the radiation graft polymerization long sheet material in the same manner as described above, By operating the take-up roll 9 with each process of the apparatus as a reaction condition, all of the long sheet material can be similarly subjected to a radiation graft polymerization treatment. In addition, this eliminates the trouble of attaching the sheet material along the conveying line in the apparatus every time the roll is replaced, leading to a significant labor saving.

  The long sheet for transportation (dummy sheet) that can be used for the above purpose is made of inorganic fibers such as halogenated polyolefins, polyethylene terephthalate, polyurethane fibers, vinylon fibers, cellulose fibers, and glass fibers. Non-porous films, net materials, woven / nonwoven fabrics and the like can be mentioned.

In the above method according to the sixth aspect of the present invention, radiation graft polymerization treatment can be performed using a long woven / nonwoven fabric material composed of ordinary polymer monofilaments. The fiber may become brittle, and problems such as breaking of the woven / non-woven long material may occur during conveyance in the apparatus by winding the roll. However, such a problem is that a woven or non-woven long sheet substrate and a sheet conveying support material (conveying sheet) having the same length as the long sheet substrate are joined together and wound together. It can be solved by transporting the woven or non-woven long sheet base material in the apparatus by winding it with a take-up roll. By using such a transport sheet, it is possible to avoid a situation in which a woven fabric or a nonwoven fabric long sheet base material is broken due to the winding tension of the roll, without considering the strength of the long sheet base material. Can be wound with a certain amount of force. As means for carrying out this method, for example, as shown in FIG. 7, a roll 7 of a woven or non-woven long sheet substrate and a roll 7 of a transport sheet having a length equivalent to the long sheet substrate. 'And prepare them in a nitrogen replacement tank, transport the joined sheets along the line in the equipment, pass through the graft reaction tank, separate the sheets and wind up each The method of winding up to roll 9 and 9 'is mentioned.

  As a support material (conveyance sheet) for sheet conveyance that can be used for the above-mentioned purposes, halogenated polyolefins, polyethylene terephthalate, polyurethane fibers, vinylon fibers, cellulose fibers, glass fibers, and other inorganic fibers are used as materials. A net material, a film, a woven / nonwoven fabric, or the like can be used.

  Furthermore, a woven / nonwoven material in which the reinforcing materials according to the first and second aspects of the present invention are combined is used as the long sheet material that is subjected to the radiation graft polymerization treatment according to the method according to the sixth aspect of the present invention. Or using a woven / nonwoven material composed of mixed polymer fibers according to the third aspect of the present invention, or in the radiation graft polymerization treatment step according to the sixth aspect of the present invention, By grafting only the surface portion of the fiber according to the fifth aspect, the strength of the woven fabric / nonwoven fabric material is maintained, thereby ensuring the strength of the fiber itself, and the sheet base by the roll winding tension as described above. In addition to solving problems such as material breakage, the base material after grafting is fragile and fibers are likely to fall off, and the size of the base material is greatly reduced by grafting. The problem of the base material itself, such as results in can be solved.

  That is, the seventh aspect of the present invention is the first step of irradiating a woven or non-woven substrate with an electron beam in a nitrogen atmosphere; the irradiated substrate is brought into contact with a predetermined amount of monomer in a nitrogen atmosphere. A long woven fabric comprising: a second step of conducting; a third step of graft-polymerizing the contacted monomer and the substrate in a nitrogen atmosphere; and performing the first to third steps continuously Or a method of radiation graft polymerization of a nonwoven fabric substrate, wherein the woven fabric or nonwoven fabric substrate is a woven fabric or nonwoven fabric composed of polymer fibers, and a polymer reinforcing material having a higher strength and a slower radiation graft polymerization rate than the polymer fibers A woven or nonwoven polymer substrate for radiation graft polymerization, or a polymer fiber and another polymer fiber having a radiation graft polymerization rate slower than that of the polymer fiber. It said method characterized by that the formed a woven or nonwoven radiation-induced graft polymerization for the polymer substrate and said related. Furthermore, an eighth aspect of the present invention is a first step of irradiating a woven or nonwoven fabric substrate composed of polymer fibers with an electron beam in a nitrogen atmosphere; the irradiated substrate in a nitrogen atmosphere. A second step of contacting a predetermined amount of the monomer; a third step of graft polymerizing the contacted monomer and the substrate in a nitrogen atmosphere; and performing the first to third steps continuously. A radiation graft polymerization method for a long woven fabric or a nonwoven fabric substrate, wherein the radiation graft polymerization reaction is performed under the condition that only the surface portion of the fiber is subjected to radiation graft polymerization and the center portion of the fiber is in an ungrafted state. It relates to the above method characterized in that it is carried out below.

INDUSTRIAL APPLICABILITY According to the present invention, a polyethylene graft polymerization base material exhibiting excellent characteristics can be obtained using polyethylene in the form of a woven fabric or a nonwoven fabric that has not been used so far.

First, in the first and second aspects of the present invention, since the reinforcing material is introduced, the strength of the nonwoven material itself is increased, and further, a graft polymerization reaction step, an ion exchange group introduction reaction step, a filter molding process step Since no decrease in strength is exhibited, breakage and defects of the nonwoven fabric material in these steps are eliminated. In addition, when the graft polymerization base material according to the first aspect of the present invention is graft-polymerized, undulations are formed on the surface of the base material. Therefore, when this is formed into a pleated shape to form a filter, for example, Without the ability to adsorb, without using a separator that causes a reduction in the effective filtration area of the filter, the spacing between the pleats can be kept constant, and also in the reinforcing material part, graft polymerization is performed, Since the functional functional group is introduced, the function of the entire filter can be further improved. Further, since no separator is used, the weight of the filter can be reduced. Furthermore, the manufacturing process of the filter is simplified, and the cost can be reduced.

  Further, in the fourth aspect of the present invention, a polyethylene graft polymerization treatment using polyethylene fibers or polymer fibers in the form of a woven or non-woven fabric and having excellent physical strength and high graft ratio without using a reinforcing material. A material is obtained. In addition, by applying the idea of the present invention to a wide range of polymer materials, a polymer graft polymerized material having excellent physical strength and high graft ratio can be obtained.

  The graft polymerization treatment material according to the first to fifth aspects of the present invention is useful as an air cleaning chemical filter material, an ion exchange filter material used in a pure water production apparatus, or the like.

  Furthermore, in the sixth aspect of the present invention, it is possible to continuously subject a long base material to a radiation graft polymerization process, which has been difficult in the past, and mass production of a long woven or non-woven material is possible. Became. Further, the radical utilization efficiency is high, the amount of monomer consumption is small, and a washing step after the graft polymerization reaction is unnecessary. This makes it possible to reduce manufacturing costs. Furthermore, the quality of the graft polymerized product was stabilized and the yield was improved.

  Furthermore, according to the seventh and eighth aspects of the present invention, it is possible to continuously perform the radiation graft polymerization treatment while maintaining the strength of the long base material, thereby improving the quality of the graft polymerization product. We were able to.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
Example 1
A nonwoven fabric was formed using polyethylene fibers having a fiber diameter of 20 μm and embossed to produce a nonwoven fabric material having a basis weight of 60 g / m ² and a thickness of about 0.35 mm. A 100d (denier) polyethylene filament was woven into a mesh at intervals of 2 to 3 mm in the longitudinal direction and the width direction as a reinforcing material. The tensile strength of the obtained reinforced nonwoven fabric substrate was 12 kg / 5 cm in the longitudinal direction and 5 kg / 5 cm in the width direction, and had sufficient strength.

  This substrate was irradiated with an electron beam of 50 kGy and reacted with glycidyl methacrylate for 2 hours to obtain a graft ratio of 146%. The filament was taken out from a part of the graft base material and the graft ratio of the filament reinforcing material alone was measured to be 37%. Thereby, the graft ratio of the polyethylene fiber nonwoven fabric alone was calculated to be about 160%. The shape of the surface of the substrate before and after grafting is shown in FIGS. 2 and 3 (micrographs). The thickness of the substrate increased to about 1.7 mm due to the formation of irregularities on the surface as shown in FIG. The nonwoven fabric substrate was sulfonated with a sodium sulfite solution to obtain a filament-reinforced strongly acidic cation exchange fiber nonwoven fabric. The neutral salt decomposition capacity was measured and found to be 2.77 meq / g.

  The tensile strength of the grafted nonwoven fabric material is 17 kg / 5 cm in the longitudinal direction and 9 kg / 5 cm in the width direction, which is higher than before graft polymerization, and the nonwoven fabric shape cannot be maintained even in the ion exchange group introduction process. The fiber pieces were not dropped off.

Using this material, a pleated filter having a cross section of 100 mm square, a depth of 50 mm, and 10 peaks was formed. At this time, molding was performed without using a conventional separator. Using the gas adsorption test apparatus shown in FIG. 8, 5 ppm of ammonia gas was passed through the filter at a rate of 200 L / min. In FIG. 8, 101 is a permeator, 102 is a gas sampling line, 103 is a filter mounting portion, 104 is a suction pump, and 105 is a flow meter. The initial ammonia removal rate exceeded 99%. After about 23 hours, the gas passage was stopped when the removal rate dropped to 90%. The exchange capacity consumption rate was 78%.
Comparative Example 1
Except that the polyethylene filament reinforcing material was not knitted, the same non-woven fabric as in Example 1 was subjected to radiation graft polymerization and sulfonation reaction as in Example 1.

  The tensile strength of the nonwoven fabric material before graft polymerization was as low as 0.35 kg / 5 cm in the longitudinal direction and 0.07 kg / 5 cm in the width direction. The graft ratio was 131%, and in the shape after polymerization, a lump of fibers was observed in some places and the thickness varied from 1 to 5 mm, but the shape of the nonwoven fabric was maintained.

The shape of the nonwoven fabric after the sulfonation reaction is difficult to handle, and even if it is handled with care, it becomes cottony and cannot be processed into a filter.
Example 2
A nonwoven fabric having a basis weight of 65 g / m ² and a thickness of 0.4 mm was formed using polyethylene fibers having a fiber diameter of 10 to 30 μm, and polyethylene nets were heat-sealed on both sides to obtain a base material for radiation graft polymerization. The polyethylene net is formed by tearing a polyethylene film with a thickness of about 0.8 mm into a thread shape, arranging this in a mesh shape with a mesh width of 5 mm, and forming a net in which threads are diagonally arranged between the vertical and horizontal lines. Thus, strength reinforcement was performed. This was irradiated with an electron beam of 50 kGy and reacted with glycidyl methacrylate for 2 hours to obtain a graft ratio of 193%. The shape of the surface of the base material before and after graft polymerization is shown in FIGS. 4 and 5 (micrographs). Under the same conditions, only polyethylene net was subjected to radiation graft polymerization and the graft ratio of polyethylene net alone was measured and found to be 70%. Thereby, the graft ratio of the polyethylene nonwoven fabric alone excluding the net was calculated to be 275%. The thickness of the nonwoven fabric material after the radiation graft polymerization increased to about 4.2 mm due to the formation of irregularities. This nonwoven fabric was sulfonated with a sodium sulfite solution to obtain a net reinforced strongly acidic cation exchange fiber nonwoven fabric having a neutral salt decomposition capacity of 2.98 meq / g.

  The tensile strength of this nonwoven fabric material is 8 kg / 5 cm in the longitudinal direction before graft polymerization and 7 kg / 5 cm in the width direction, and has sufficient strength. Even after graft polymerization and sulfonation reaction, the longitudinal direction 9kg / 5cm in the width direction and 15kg / 5cm in the width direction, and it was rather strong. During the above treatment, no change in the shape of the polyethylene fibers or dropping of the fiber pieces was observed.

Using this material, a pleated filter having a cross section of 100 mm square, a depth of 50 mm, and 7 peaks was formed without using a conventional separator. Using the experimental apparatus shown in FIG. 8, 2 ppm of ammonia gas was passed through the filter at a rate of 200 L / min. The initial ammonia removal rate was over 98%. Gas passing was stopped when the removal rate dropped to 90% after about 61 hours. The exchange capacity consumption rate was 74%.
Comparative Example 2
A non-woven fabric composed of the same polyethylene fibers as in Example 2 except that the polyethylene net was not thermally fused was subjected to radiation graft polymerization and sulfonation reaction under the same conditions as in Example 2 to obtain a neutral salt decomposition capacity. A strongly acidic cation exchange nonwoven fabric material of 3.04 meq / g was obtained. The nonwoven fabric material had a tensile strength of 6 kg / 5 cm in the longitudinal direction and 2 kg / 5 cm in the width direction, and was carefully handled to maintain the shape of the nonwoven fabric.

Using this nonwoven fabric material, a pleated filter similar to that of Example 2 was manufactured and a gas flow test was attempted. However, due to the “sagging” of the nonwoven fabric, the pressure loss increased and the gas flow rate was 132 L / min. Only reached. Therefore, an aluminum corrugated separator having a width of 5 mm was inserted between the pleat crests. Using this filter, the same gas flow test as in Example 2 was performed. The removal rate was 99% at the beginning of gas passing. The gas passing was stopped when the removal rate reached 90%, but the exchange capacity consumption rate was 59%, which was lower than 74% in Example 2.
Example 3
Using a mixed fiber in which a polyethylene fiber having a fiber diameter of about 20 μm and a polyethylene terephthalate fiber having a fiber diameter of 15 μm were mixed at a quantitative ratio of 75:25, a nonwoven fabric substrate having a basis weight of 45 g / m ² and a thickness of 0.25 mm was formed. . The nonwoven fabric had a tensile strength of 8.2 kg / 5 cm in the longitudinal direction and 6.7 kg / 5 cm in the width direction.

  When this non-woven fabric substrate sample (20 cm × 20 cm, 1.89 g (ie, polyethylene 1.42 g)) was subjected to radiation graft polymerization in the same manner as in Example 1, 4.67 g of a graft product was obtained. That is, a 196% graft ratio of glycidyl methacrylate to polyethylene was obtained. The nonwoven material was sulfonated in the same manner as in Example 1 to obtain a strongly acidic cation exchange nonwoven fabric having a neutral salt decomposition capacity of 2.72 meq / g.

This nonwoven fabric had dimensions of 19.4 cm × 20.0 cm and a thickness of 0.63 mm, and there was almost no dimensional change in the longitudinal direction and the width direction, except that the thickness increased. In addition, the tensile strength is 7.5 kg / 5 cm in the longitudinal direction and 6.1 kg / 5 cm in the width direction. The decrease in tensile strength is slight, and the strength is sufficient for filter processing. It was strong enough to withstand the conveyance for.
Example 4
A nonwoven fabric substrate having a basis weight of 55 g / m ² was produced by spot welding using 6 denier high density polyethylene fiber. The tensile strength of the base material was 5.3 kg / 5 cm in the longitudinal direction and 4.1 kg / 5 cm in the width direction.

  This nonwoven fabric substrate was irradiated with an electron beam of 150 kGy in a nitrogen atmosphere and then impregnated with 130% of the weight of the nonwoven fabric by glycidyl methacrylate and reacted at 50 ° C. for 4 hours. As a result, a grafting ratio of 124% of glycidyl methacrylate was obtained. It was. The graft-treated nonwoven fabric substrate was immersed in an aqueous solution of 10% sodium sulfite and 10% isopropyl alcohol and reacted at 80 ° C. for 8 hours to effect sulfonation to obtain a strongly acidic cation exchange fiber nonwoven fabric material. The neutral salt decomposition capacity was measured and found to be 2.61 meq / g.

The distribution of sulfur atoms in the fiber cross section of the grafted nonwoven material was observed with SEM-XMA (Scanning Electron Microscope-X-ray Microanalyzer). A SEM-XMA photograph is shown in FIG. FIG. 9a is a SEM of the fiber cross section
FIG. 9b is an XMA photograph showing the distribution of sulfur atoms in the fiber cross section. FIG. 9b shows that sulfur atoms are present in about 1/3 of the radius of the fiber cross section, so that 1/3 of the surface is grafted and about 2/2 from the center. The part 3 was shown to remain ungrafted. The tensile strength of this nonwoven fabric material was 4.6 kg / 5 cm in the longitudinal direction and 3.7 kg / 5 cm in the width direction in the dry state, which was only about 10% lower than before the treatment. There was no hindrance.
Comparative Example 3
A nonwoven fabric substrate having a basis weight of 60 g / m ² was manufactured by spot welding using 6 denier low density polyethylene fibers. The tensile strength of the base material is 4.4 kg / 5c in the longitudinal direction.
m, 3.7 kg / 5 cm in the width direction. This nonwoven fabric substrate was subjected to radiation graft polymerization in the same manner as in Example 1 to effect sulfonation. The graft ratio of glycidyl methacrylate before sulfonation over the entire substrate was 130%. A strongly acidic cation exchange fiber nonwoven fabric material having a neutral salt decomposition capacity of 2.77 meq / g was obtained. However, the strength of the fibers is insufficient, and in some cases, the shape of the nonwoven fabric cannot be maintained and becomes cottony. The distribution of sulfur atoms in the fiber cross section of the grafted material was observed with SEM-XMA. An SEM photograph and an XMA photograph are shown in FIG. FIG. 10a is an SEM photograph of the fiber cross section, and FIG. 10b is an XMA photograph showing the distribution of sulfur atoms in the fiber cross section. From FIG. 10b, it was found that sulfur atoms exist up to the center of the fiber cross section, and therefore the grafting reaction proceeds to the center of the fiber cross section. Therefore, in contrast to the case of Example 4, in Comparative Example 3, the graft sites were dispersed throughout the cross section of the base material, and in Example 4, the graft was formed at a higher density on the surface portion of the base material. It is understood that it is done.

The tensile strength of this grafted nonwoven material is drastically reduced to 1.4 kg / 5 cm in the longitudinal direction and 0.3 kg / 5 cm in the width direction in the dry state. If this is processed into a pleated filter material, the nonwoven fabric may be torn. The strength was insufficient, such as a large amount of fine fiber waste.
Example 5
A roll 7 of a nonwoven fabric long sheet (50 cm width × 600 m) having a weight per unit area of 50 g / m ² and a thickness of 0.3 mm formed from a polyethylene (PE) single fiber having a fiber diameter of about 15 μm is shown in FIG. It put into the nitrogen substitution tank 1, and the edge part of the sheet | seat was joined to the dummy net | network. The dummy net is from the take-up roll 9 through the graft polymerization treatment tank 5, the monomer impregnation tank 4, and the radiation irradiation device 3, and the end reaches the nitrogen substitution tank 1, and by winding this, The nonwoven fabric sheet 2 for irradiation is sequentially sent out.

  Close the shutter provided on the wall of the nitrogen replacement tank 1 and the irradiation chamber 3 and the space between the nitrogen irradiation tank 3 and the nitrogen replacement tank, and repeat the pressure reduction to 50 mmHg and the nitrogen introduction to the atmospheric pressure twice. Nitrogen replacement was performed.

  Next, the cooling nitrogen which vaporized liquid nitrogen was introduce | transduced from this compartment, the temperature of the irradiation part of the radiation irradiation apparatus 3 was set to -20 degreeC, and oxygen concentration was 200-on the exit side of the graft polymerization processing tank 5. Set to 300 ppm.

The irradiation conditions of the radiation irradiation device 3 were set to 300 keV and 15 mA, and the driving roll and the winding device were adjusted so that the dummy net transport speed was 2 m / min.
Next, the dummy net is wound, and the nonwoven fabric sheet 2 bonded to the end of the net is sequentially carried into the radiation irradiation apparatus, irradiated with radiation, and further impregnated with the glycidyl methacrylate solution in the monomer impregnation tank 4, In the next graft polymerization treatment tank 5, a graft polymerization reaction was carried out at 50 ° C. for 20 minutes. The drawing roll was adjusted so that the impregnation ratio of the monomer into the nonwoven fabric sheet was 120% using another nonwoven fabric sheet in advance.

  Table 1 shows the results of calculating the graft ratio for every 100 m of the 600 m roll sheet by the basis weight measurement of the obtained graft polymerization treated nonwoven fabric sheet. Considering the variation in the basis weight of the nonwoven fabric substrate itself, it can be seen that a very uniform graft polymerization-treated long nonwoven fabric sheet was obtained.

  The graft ratio was determined by the following equation by immersing the obtained graft polymer in a dimethylformamide solution at 60 ° C. for 6 hours, washing with methanol, drying and measuring the weight.

Formula 1

Comparative Example 4
The long non-woven sheet material was subjected to graft polymerization under the same conditions except that the oxygen concentration was set to 1300 ppm on the outlet side of the graft polymerization treatment tank 5. It was speculated that the wound graft polymerization treated nonwoven material was wet with unreacted monomers, and the graft polymerization did not proceed sufficiently.

  When the graft ratio was measured in the same manner as in Example 4, it was as shown in Table 2. Although the graft ratio has increased slightly from around 300 m of winding, this is considered to be because the oxygen concentration was slightly decreased by the nitrogen stream.

Example 6
The same nonwoven fabric long sheet as that used in Example 5 was used, and the treatment was performed in the same manner as in Example 5. However, the oxygen concentration at the outlet side of the graft polymerization treatment tank 5 is set to 50 to 100 ppm, the irradiation condition of the radiation irradiation apparatus 3 is set to 275 keV, 3 mA, and the conveyance speed of the dummy net is 1.5 m / min. Adjusted. Moreover, all the conveyance rolls in the graft polymerization treatment tank 5 were not used, and were appropriately bypassed to adjust the residence time in the graft polymerization treatment tank 5 to 20 minutes.

A result almost the same as that of Example 5 was obtained, and a high graft ratio was obtained over the entire roll. Example 7
A long nonwoven fabric sheet material was formed from the same reinforcing nonwoven fabric substrate as used in Example 1 (width 500 mm × length 600 m), and a radiation graft polymerization treatment was performed in the same manner as in Example 5. As a result, the graft ratio from 0 to 600 m was in the range of 135% ± 15% as in Example 5, and a uniform graft product was obtained.

Further, the width dimension was 500 ± 3 mm while the original fabric was 500 ± 5 mm after the graft treatment, and almost no dimensional change was observed.
Example 8
A long nonwoven fabric sheet material is formed from a nonwoven fabric substrate made of high-density polyethylene fibers similar to that used in Example 4 (width 500 mm × length 600 m), and a radiation graft polymerization treatment is performed in the same manner as in Example 5. went.

As a result, the graft ratio from 0 to 600 m was in the range of 135% ± 19% as in Example 5, and a practically sufficiently uniform graft product was obtained.
Further, the width dimension was 500 ± 5 mm for the original fabric, but 500 ± 12 mm after the graft treatment, and practically no problem was recognized.
Comparative Example 5
A long nonwoven fabric sheet material is formed from a nonwoven fabric substrate made of low-density polyethylene fibers similar to that used in Comparative Example 3 (width 500 mm × length 600 m), and radiation graft polymerization treatment is performed in the same manner as in Example 5. went.

  As a result, the width shrunk to 400 mm or less from the start of the reaction, and the sheet was torn when 43 m was drawn. The strength against the tension in the length direction of the sheet was insufficient, and it was impossible to react as a fabric.

Embodiments of the present invention are as follows.
1. A woven or non-woven fabric for radiation graft polymerization, comprising a woven or non-woven fabric composed of polymer fibers and a polymer reinforcing material having a strength higher than that of the polymer fibers and a slow rate of radiation graft polymerization. Base material.

  2. A base material for radiation graft polymerization in the form of a woven or non-woven fabric comprising a woven or non-woven fabric composed of polyethylene fibers and a polyethylene material having a strength higher than that of the polyethylene fibers and a slow rate of radiation graft polymerization. .

3. 3. The substrate for radiation graft polymerization according to item 1 or 2, wherein the reinforcing material is in the form of a filament and is woven into a woven or non-woven fabric.
4). 3. The substrate for radiation graft polymerization according to item 1 or 2, wherein the reinforcing material has a net shape and is bonded to the surface of a woven fabric or a non-woven fabric.

  5. A polymer substrate for radiation graft polymerization in the form of a woven fabric or a nonwoven fabric, wherein a polymer fiber and another polymer fiber having a radiation graft polymerization rate slower than that of the polymer fiber are mixed to form a woven fabric or a nonwoven fabric.

6). 6. The polymer substrate for radiation graft polymerization according to item 5, wherein the polymer fiber is a polyethylene fiber and the other polymer fiber is a polyethylene terephthalate fiber.
7). A filter material having undulations on the surface, wherein a functional functional group is introduced into the base material for radiation graft polymerization according to any one of items 1 to 6 using radiation graft polymerization. .

8). The filter material according to claim 7, wherein the functional functional group is an ion exchange group.
9. 9. The filter material according to item 8, wherein glycidyl methacrylate is introduced into a woven or non-woven substrate by radiation graft polymerization, and an ion exchange group is introduced into the glycidyl methacrylate.

10. A filter, wherein the filter material according to any one of Items 7 to 9 is formed into a pleated shape.
11. A radiation-grafted material, which is a woven or non-woven material composed of a single polymer fiber, wherein only the surface portion of the fiber is subjected to radiation graft polymerization, and the center portion of the fiber is in a non-grafted state.

  12 A woven or non-woven fabric for radiation graft polymerization, comprising a woven or non-woven fabric composed of polymer fibers and a polymer reinforcing material having a strength higher than that of the polymer fibers and a slow rate of radiation graft polymerization. A radiation grafted material obtained by subjecting a substrate to radiation graft polymerization, wherein only the surface portion of the polymer fiber is subjected to radiation graft polymerization, and the central portion of the polymer fiber is in a non-grafted state. Radiation graft processing material.

  13. A polymer substrate for radiation graft polymerization in the form of a woven or non-woven fabric, characterized in that a polymer fiber and another polymer fiber having a radiation graft polymerization rate slower than that of the polymer fiber are mixed to form a woven or non-woven fabric. Radiation graft treatment material obtained by radiation graft polymerization treatment, wherein only the surface portion of the polymer fiber is subjected to radiation graft polymerization treatment, and the central portion of the polymer fiber is in a non-grafted state. material.

14 The radiation graft treatment material according to any one of the above items 11 to 13, wherein the woven fabric or the nonwoven fabric material is composed of polyethylene monofilament.
15. 15. The radiation grafting material according to item 14, wherein the polyethylene is high density polyethylene.

16. The radiation graft treatment material according to any one of the above items 11 to 15, wherein a functional functional group is introduced by using radiation graft polymerization.
17. The filter material comprised from the radiation graft processing material of the said 16th item whose functional functional group is an ion exchange group.

  18. Item 18. The ion exchange filter material according to Item 17, wherein the functional functional group is a sulfone group, a quaternary ammonium group, or a tertiary amino group introduced via glycidyl methacrylate.

  19. Item 18. The filter material according to Item 17, wherein the functional functional group is an ion exchange group introduced by grafting sodium styrenesulfonate, vinylbenzyltrimethylammonium chloride or acrylic acid.

  20. Control conditions under which a woven or non-woven fabric is formed from a single polymer fiber, and only the surface portion of the woven or non-woven fabric is subjected to radiation graft polymerization treatment, and the central portion of the fiber remains in an ungrafted state. 17. The method for producing a radiation graft treatment material according to any one of the above items 11 to 16, wherein the radiation graft polymerization treatment is carried out.

21. Item 21. The method according to Item 20, wherein the radiation graft polymerization treatment is performed by a pre-irradiation impregnation graft polymerization method.
22. A woven or non-woven fabric is formed from a single polymer fiber, and radiation is applied to the woven or non-woven fabric under such a condition that only the surface portion of the fiber is subjected to a radiation graft polymerization treatment and the central portion of the fiber remains in an ungrafted state. 18. Glycidyl methacrylate is introduced by carrying out a graft polymerization treatment, which is then sulfonated by reacting with sodium sulfite or aminated in an aqueous solution of diethanolamine. Manufacturing method of ion exchange filter material.

23. A woven or non-woven fabric is formed from a single polymer fiber, and radiation is applied to the woven or non-woven fabric under such a condition that only the surface portion of the fiber is subjected to a radiation graft polymerization treatment and the central portion of the fiber remains in an ungrafted state. 18. The method for producing an ion exchange filter material according to item 17, wherein sodium styrenesulfonate, vinylbenzyltrimethylammonium chloride or acrylic acid is introduced by performing graft polymerization.

  24. A first step of irradiating a woven or non-woven substrate with an electron beam in a nitrogen atmosphere; a second step of bringing the irradiated base material into contact with a predetermined amount of monomer in a nitrogen atmosphere; A radiation graft polymerization method for a long woven fabric or a nonwoven fabric base material, comprising: a third step of graft polymerization of a material in a nitrogen atmosphere, wherein the first step to the third step are continuously performed.

  25. Item 25. The above item 24, wherein a preliminary step of replacing the air present in the base material with nitrogen gas is performed before the first step of irradiating the base material with an electron beam, and the preliminary step to the third step are continuously performed. A radiation graft polymerization method for a long woven fabric or a nonwoven fabric substrate.

  26. In the second step, the contact between the base material and the monomer is performed by immersing the base material in the monomer solution and then removing the monomer liquid unnecessary for the graft polymerization from the base material. A radiation graft polymerization method for a long woven fabric or a nonwoven fabric substrate.

27. 27. The radiation graft polymerization method for a long woven fabric or a nonwoven fabric base material according to any one of the above 24th to 26th items, wherein the oxygen concentration in the nitrogen atmosphere in the third step is 1000 ppm or less.
28. In the first step, the electron beam irradiation conditions are a voltage of 100 keV to 500 keV, an electron beam current of 3 mA to 50 mA, and an irradiation dose of 30 kGy to 200 kGy. A method of radiation graft polymerization of a nonwoven fabric substrate.

  29. In the first step, radiation graft polymerization of the long woven fabric or the non-woven fabric substrate according to any one of Items 24 to 28, wherein the temperature of the substrate at the time of electron beam irradiation is -50 ° C to + 50 ° C. Method.

  30. 30. The radiation graft polymerization method for a long woven fabric or a nonwoven fabric base material according to any one of the above items 25 to 29, wherein in the preliminary step, nitrogen substitution is performed by repeating reduced-pressure exhaust and nitrogen introduction at least once.

  31. A woven or non-woven radiation graft comprising a woven or non-woven base material composed of polymer fibers and a polymer reinforcing material having a higher strength and a slower radiation graft polymerization rate than the polymer fibers. 31. The radiation graft polymerization method as described in any one of 24 to 30 above, which is a polymer substrate for polymerization.

  32. A woven or non-woven fabric substrate comprising a woven fabric or a non-woven fabric formed by mixing a polymer fiber with another polymer fiber having a radiation graft polymerization rate slower than that of the polymer fiber. 31. The radiation graft polymerization method according to any one of items 24 to 30, which is a polymer base material for radiation graft polymerization.

  33. The above-mentioned item 24, wherein the radiation graft polymerization reaction is carried out under such a condition that only the surface portion of the fiber constituting the woven or non-woven fabric substrate is subjected to radiation graft polymerization and the central portion of the fiber is in an ungrafted state. Item 33. The method according to any one of Items 32 to 32.

  34. A long material for transporting a substrate that does not need to be subjected to radiation graft polymerization treatment is joined to the front end and / or the rear end of a long woven fabric or non-woven fabric substrate, and this long material for transporting the substrate is put into the reactor. The long woven fabric or non-woven fabric base material is transported into the reactor by transporting, and after the reaction is finished, the long woven fabric or non-woven fabric base material is separated from the long material for transporting the base material and taken out. The method according to any one of Items 24 to 33.

  35. An electron beam irradiation apparatus for irradiating a woven or non-woven substrate with an electron beam in a nitrogen atmosphere; a monomer impregnation tank for bringing the irradiated substrate into contact with a predetermined amount of monomer in a nitrogen atmosphere; A graft polymerization tank for graft polymerization of the monomer and the substrate in a nitrogen atmosphere, and these are arranged in series, and a long woven fabric or a nonwoven fabric substrate is connected to each of the above devices. A continuous radiation graft polymerization processing apparatus for a long woven fabric or a nonwoven fabric base material, comprising a conveying means for continuously passing in the above order.

  36. 36. The apparatus according to the above item 35, which has a nitrogen replacement tank for replacing air existing in the woven fabric or non-woven fabric substrate with nitrogen gas in the front stage of the electron beam irradiation apparatus.

FIG. 1 is a perspective view showing the shape of the surface of a material after subjecting the reinforced nonwoven material according to the present invention to radiation graft polymerization. FIG. 2 shows a radiation graft polymerization base material comprising a nonwoven fabric composed of polyethylene fibers and a polyethylene filament reinforcing material woven into the nonwoven fabric according to the first embodiment of the present invention before radiation graft polymerization. It is a microscope picture which shows the shape of a fiber. FIG. 3 is a photomicrograph showing the shape of the fiber after radiation graft polymerization of the substrate shown in FIG. FIG. 4 shows a radiation graft polymerization of a base material for radiation graft polymerization comprising a nonwoven fabric composed of polyethylene fibers and a polyethylene net reinforcing material fused to both surfaces of the nonwoven fabric according to the first embodiment of the present invention. It is a microscope picture which shows the shape of the front fiber. FIG. 5 is a photomicrograph showing the shape of the fiber after radiation graft polymerization of the substrate shown in FIG. FIG. 6 is a diagram showing the concept of a continuous radiation graft polymerization apparatus for carrying out the method according to the sixth aspect of the present invention. FIG. 7 is a diagram showing the concept of another embodiment of the continuous radiation graft polymerization processing apparatus. FIG. 8 is a schematic view of a test apparatus used for testing the graft nonwoven fabric material according to the first embodiment of the present invention. FIG. 9 is an SEM photograph and an XMA photograph of a cross section of the high-density polyethylene radiation-grafted polymer fiber produced in Example 4. FIG. 9a is an SEM photograph of the fiber cross section, and FIG. 9b is an XMA photograph showing the distribution of sulfur atoms in the fiber cross section. FIG. 10 is an SEM photograph and an XMA photograph of a cross section of the low density polyethylene radiation graft polymerized fiber produced in Comparative Example 3. FIG. 10a is an SEM photograph of the fiber cross section, and FIG. 10b is an XMA photograph showing the distribution of sulfur atoms in the fiber cross section.

Claims (3)

A polyethylene film or net-like reinforcing material composed of polyethylene having a strength higher than that of the polyethylene fiber and a slow radiation graft polymerization rate is adhered to both surfaces of a woven fabric or a nonwoven fabric composed of polyethylene fibers. , Polymer substrate for radiation graft polymerization. The polymer substrate for radiation graft polymerization according to claim 1, wherein the surface area per unit weight of the polyethylene film or the net-like reinforcing material is smaller than the surface area per unit weight of the woven fabric or nonwoven fabric. 2. The polymer base material for radiation graft polymerization according to claim 1, wherein the diameter of the net-like reinforcing material is larger than the diameter of polyethylene fibers constituting the woven or non-woven fabric.