Water-swellable water-stopping composition

Abstract

To provide a water-swelling sealant composition that can produce a sealing material that not only expands preferentially in the thickness direction but also exhibits superior water swellability, shape retention following water-induced expansion, and flexibility.SOLUTION: The present invention provides a water-swelling sealant composition that contains rubber and / or elastomer. Relative to 100 pts.mass of the rubber and / or elastomer, the water-swelling sealant composition also contains 1-300 pts.mass of a water-absorbing resin and 1-300 pts.mass of a fibrous compound.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a water-swellable water-stopping composition that can be used to produce a sealant. [Background technology]

[0002] In the fields of civil engineering and construction, water-expanding water-stopping materials formed into tapes or films are used at the joints of various pipes, such as tunnel segments, underground fume pipes, and U-shaped gutters for water supply and sewerage, to prevent water leakage and stop water leakage.

[0003] For example, Patent Document 1 discloses a water-expandable foam sealant obtained by adding a highly water-absorbent resin containing a crosslinked sodium polyacrylate, silica, a nonionic surfactant, a vulcanizing agent and a vulcanization accelerator, and a thermally decomposable foaming agent to a vulcanizable rubber, and then subjecting the resulting mixture to a vulcanization and foaming treatment, with the aim of providing a water-expandable foam sealant that exhibits good expansion properties in water and ionized water such as seawater, has a small amount of elution into water, is lightweight, and is easy to install. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-063450 Summary of the Invention [Problem to be solved by the invention]

[0005] Sealants made using water-swellable water-stopping compositions absorb water and expand in volume when they come into contact with water, thereby achieving water-stopping properties. Because such sealants tend to expand almost uniformly in the length, width, and thickness directions, when long products are used, the absolute value of expansion in the length direction increases, which can result in partial lifting of the sealant (meandering). To prevent this, it has been necessary to insert a core material or stainless steel mesh into the sealant or firmly fix the sealant to the component with an adhesive.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a water-swellable water-stopping composition that can be used to produce a sealing material that not only expands preferentially in the thickness direction but also has excellent water-swellability, shape retention after water-swelling, and flexibility. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by using a predetermined amount of a fibrous compound, thereby completing the present invention.

[0008] That is, according to the present invention, the following inventions are provided. [1] A water-swellable waterproof composition comprising rubber and / or elastomer, and containing 1 to 300 parts by mass of a water-absorbent resin and 1 to 300 parts by mass of a fibrous compound per 100 parts by mass of the rubber and / or elastomer. [2] The water-swellable waterproof composition according to [1], which contains silica and / or clay minerals. [3] The water-swellable water-stopping composition according to [1] or [2], wherein the water-absorbent resin comprises at least one selected from the group consisting of acrylic polymers, alkylene oxide polymers, and cellulose compounds. [4] The water-swellable water-stopping composition according to any one of [1] to [3], wherein the average length of the fibrous compound is 0.5 to 10 mm. [5] The water-swellable water-stopping composition according to any one of [1] to [4], wherein the fibrous compound contains a fibrous organic compound. [6] The water-swellable water-stop composition according to any one of [1] to [5], wherein the water-swellable water-stop composition is molded into a flat plate having a thickness of 2 mm, a width of 30 mm, and a length of 30 mm, and the resulting test piece is immersed in water at 23°C for 3 days to expand, and the expanded test piece has an aspect ratio after expansion in water of less than 6. [7] The water-swellable waterproof composition according to any one of [1] to [6], which is used as a sealing material. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a water-swellable water-stopping composition that can be used to produce a sealing material that not only expands preferentially in the thickness direction but also has excellent water-swellability, shape retention after water expansion, and flexibility. DETAILED DESCRIPTION OF THE INVENTION

[0010] Below, we will explain in detail the form for implementing the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

[0011] 1.1. Water-swellable water-stopping composition <Rubber and / or elastomer> A wide range of known rubbers and / or elastomers can be used.

[0012] Examples of rubber include natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, chlorinated butyl rubber, chlorinated polyethylene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), ethylene-vinyl acetate rubber, chloroprene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, crosslinkable rubber such as reclaimed rubber, silicone rubber, fluororubber, and urethane rubber.

[0013] Examples of the elastomer include polyolefin-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, and styrene-based thermoplastic elastomers.

[0014] The styrene-based thermoplastic elastomer is preferably a block copolymer consisting of a polymer block mainly composed of a vinyl aromatic hydrocarbon and a polymer block mainly composed of a conjugated diene. Examples of vinyl aromatic hydrocarbons include styrene, p-methylstyrene, α-methylstyrene, vinylxylene, monochlorostyrene, dichlorostyrene, monobromostyrene, etc., which may be used alone or in combination of two or more. Examples of conjugated dienes include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, etc., which may be used alone or in combination of two or more.

[0015] Specific examples of styrene-based thermoplastic elastomers include styrene-butadiene-styrene (SBS) copolymer, styrene-isoprene-styrene (SIS) copolymer, styrene-ethylene-butylene-styrene (SEBS) copolymer, styrene-isoprene-hydrogenated styrene-isoprene-styrene (SEPS) copolymer, styrene-ethylene-propylene (SEP) copolymer, styrene-ethylene-propylene-styrene (SEPS) copolymer, and styrene-ethylene-ethylene-propylene-styrene (SEEPS) copolymer.

[0016] These rubbers and / or elastomers can be used singly or in combination of two or more.

[0017] <Water absorbent resin> Water-absorbent resins, also known as SAPs (Super Absorbent Polymers), are polymers with the ability to absorb 300 to 2,000 times their own weight in water and the ability to retain that water in a very stable state. Examples of water-absorbent resins include, but are not limited to, acrylic acid polymer partial sodium salts and crosslinked products thereof, acrylic acid graft polymer partial sodium salts and crosslinked products thereof, starch-acrylic acid graft polymer salts and crosslinked products thereof, saponified vinyl acetate-acrylic acid ester copolymers and crosslinked products thereof, 2-acrylamido-2-methylpropanesulfonic acid-acrylic acid copolymer salts and crosslinked products thereof, cellulose compounds such as sodium carboxymethylcellulose and ammonium carboxymethylcellulose, alkylene oxide polymers such as polyalkylene oxides and modified polyalkylene oxides, hydrolyzed starch-acrylonitrile graft polymers, hydrolyzed acrylonitrile copolymers or acrylamide copolymers or crosslinked products thereof, crosslinked products of cationic monomers, and crosslinked isobutylene-maleic acid copolymers. The water-absorbing resin may be used alone or in combination of two or more kinds.

[0018] Among these, it is preferable to contain at least one selected from the group consisting of acrylic polymers, alkylene oxide polymers, and cellulose compounds, and more preferably partial sodium salts of acrylic acid polymers or crosslinked products thereof, partial sodium salts of acrylic acid graft polymers or crosslinked products thereof, sodium carboxymethylcellulose, and modified polyalkylene oxides. By using such water-absorbent resins, water swelling properties tend to be further improved.

[0019] The content of the water-absorbent resin is 1 to 300 parts by mass, preferably 20 to 230 parts by mass, and more preferably 45 to 150 parts by mass, per 100 parts by mass of the rubber and / or elastomer. When the content of the water-absorbent resin is 1 part by mass or more, water swelling tends to be further improved. Furthermore, when the content of the water-absorbent resin is 300 parts by mass or less, cracking is further suppressed, and shape retention tends to be further improved. The content of the water-absorbing resin is, for example, 1, 5, 10, 20, 30, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 parts by mass per 100 parts by mass of the rubber and / or elastomer, and may be within a range between any two of the numerical values ​​exemplified here.

[0020] <Fibrous compounds> The shape of the fibrous compound may be any as long as it is fibrous, and the cross-sectional shape of the fiber may be, for example, circular, elliptical, polygonal, etc. The L / D of the fiber is, for example, more than 10, preferably 50 or more, and more preferably 100 or more. The upper limit is not particularly specified, but is, for example, 10,000. The diameter of the fiber is, for example, 1 to 100 μm, preferably 2 to 50 μm, and more preferably 5 to 20 μm.

[0021] The average length of the fibrous compound is, for example, 0.1 to 20 mm, preferably 0.25 to 15 mm, and more preferably 0.5 to 10 mm. This average fiber length is, for example, 0.1, 0.2, 0.25, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mm, and may be within a range between any two of the values ​​exemplified here.

[0022] The average length of the fibrous compound can be calculated by measuring the lengths of a sufficiently large number of fibrous compounds, i.e., 20 or more, and averaging the measured lengths. The length of each fibrous compound can be measured using, for example, a field emission scanning electron microscope (FE-SEM).

[0023] The fibrous compound contains at least one of a fibrous organic compound and a fibrous inorganic compound, and preferably contains a fibrous organic compound, because in this case, the aspect ratio after water expansion, which will be described later, tends to be particularly small.

[0024] Examples of fibrous organic compounds include meta-aramid fibers, para-aramid fibers, amide fibers, cellulose fibers (e.g., pulp fibers), polyparaphenylenebenzbisoxazole fibers, polyarylate fibers, polyester fibers, acrylic fibers, acrylonitrile fibers, rayon, silk, cotton, hemp, and wool.

[0025] Examples of fibrous inorganic compounds include glass fibers (E glass fibers, C glass fibers, S glass fibers, D glass fibers), rock wool, ceramic fibers (silica alumina fibers, alumina fibers, silica fibers), zirconia fibers, carbon fibers, sepiolite, palygorskite, wollastonite, bulk alkaline earth silicate fibers, gypsum fibers, carbon fibers, metal fibers, slag fibers, and basalt fibers.

[0026] The content of the fibrous compound is 1 to 300 parts by mass, preferably 6 to 200 parts by mass, and more preferably 12 to 110 parts by mass, per 100 parts by mass of the rubber and / or elastomer. If the content of the fibrous compound is less than 1 part by mass, the aspect ratio after water expansion (described below) becomes too large. On the other hand, if the content of the fibrous compound exceeds 300 parts by mass, flexibility is impaired and flexibility is poor. The content of the fibrous compound is, for example, 1, 3, 6, 9, 12, 20, 30, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, or 300 parts by mass per 100 parts by mass of the rubber and / or elastomer, and may be within a range between any two of the numerical values ​​exemplified here.

[0027] <Silica and / or clay minerals> The water-swellable water-stopping composition of this embodiment preferably contains silica and / or a clay mineral. By blending silica and / or a clay mineral, the water-swellability of the composition of this embodiment can be increased.

[0028] Examples of silica include crystalline silica, amorphous anhydrous silica, and hydrated amorphous silica. The clay mineral used is at least one selected from natural or synthetic inorganic clay minerals. Examples of clay minerals include smectite clays such as bentonite, montmorillonite, and hectorite; fibrous clays such as sepiolite and palygorskite; sericite, illite, glauconite, chlorite, talc, zeolite, beidellite, nontronite, saponite, hectorite, sauconite, stevensite, cristopalite, smectite, and kaolin. These inorganic compounds may be used alone or in combination.

[0029] The content of silica and / or clay mineral is, for example, 0.5 to 310 parts by mass, preferably 1 to 300 parts by mass, more preferably 20 to 220 parts by mass, and even more preferably 40 to 140 parts by mass, per 100 parts by mass of rubber and / or elastomer. If the amount of silica and / or clay mineral is too small, water swelling tends to be insufficient, while if the amount of silica and / or clay mineral is too large, flexibility tends to be poor. The content of silica and / or clay mineral is, for example, 0.5, 1, 3, 6, 9, 12, 20, 30, 40, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, or 310 parts by mass per 100 parts by mass of rubber and / or elastomer, and may be within a range between any two of the numerical values ​​exemplified here.

[0030] <Other inorganic compounds> The water-swellable water-stopping composition of the present embodiment may contain other inorganic compounds. The other inorganic compounds are inorganic compounds other than fibrous compounds, silica, and clay minerals. By blending the other inorganic compounds, the water-swellability can be increased.

[0031] Other inorganic compounds include, for example, metal oxides such as alumina, aluminosilicate, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, aluminum hydroxide, and ferrites; hydrated inorganic substances such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, and hydrotalcite; metal carbonates such as basic magnesium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, strontium carbonate, and barium carbonate; and calcium sulfate and calcium silicate. Examples include calcium salts, glass beads, silica-based balloons, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon balloons, charcoal powder, various metal powders, potassium titanate, magnesium sulfate, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, zinc borate, various magnetic powders, fly ash, inorganic hollow fillers, perlite, obsidian, perlite, rosin, diatomaceous earth, dewatered sludge, boron, sodium tetraborate hydrate (borax), and inorganic phosphorus compounds.

[0032] The content of the other inorganic compounds is, for example, 1 to 300 parts by mass, preferably 20 to 220 parts by mass, and more preferably 40 to 140 parts by mass, per 100 parts by mass of the rubber and / or elastomer. If the content of the other inorganic compounds exceeds 300 parts by mass, flexibility is impaired and flexibility is poor.

[0033] <Other additives> In addition to the above components, the water-swellable water-stopping composition of this embodiment may also contain various additives, such as antioxidants, ultraviolet inhibitors, tackifying resins, lubricants, dispersants, and softeners, which are commonly used in rubber, as needed.

[0034] 1.2.Physical Properties The water-swellable water-stopping composition of this embodiment preferably has excellent water-swelling properties. The water-swelling properties can be evaluated based on the volume change rate of a test piece before and after immersion. Furthermore, the water-swellable water-stopping composition of this embodiment preferably has a small aspect ratio after swelling in water.

[0035] The test piece can be obtained by molding the water-swellable water-stopping composition into a flat plate having a thickness of 2 mm, a width of 30 mm and a length of 30 mm.

[0036] The volume change rate of the test piece before and after immersion can be calculated using the following formula in accordance with JIS K-6258 after immersing the test piece in water at 23°C for 3 days. Volume change rate (%) = {((cd)-(ab)) / (ab)} x 100 a: Weight in the air before immersion, b: Weight in water before immersion c: Weight in air after immersion in water, d: Weight in water after immersion in water

[0037] The volume change rate of the test piece before and after immersion is, for example, 100 to 1000%, such as 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 700, 800, 900, or 1000%, and may be within a range between any two of the values ​​exemplified here, or may be greater than or less than any of these values.

[0038] The aspect ratio after expansion in water refers to the aspect ratio of the expanded test specimen after immersion in water at 23°C for 3 days to expand it. The aspect ratio is the ratio of the horizontal width to the vertical thickness. In the case of a flat test specimen or expanded test specimen, the vertical direction can be considered to be the thickness direction, and the horizontal direction can be considered to be the width direction. Therefore, the aspect ratio of the test specimen or expanded test specimen can be calculated by dividing the average dimension of the four horizontal sides of the test specimen or expanded test specimen by the maximum vertical dimension.

[0039] The aspect ratio of the flat test specimen is 15, and the aspect ratio of the expanded test specimen (i.e., the aspect ratio after expansion in water) is preferably less than 10, more preferably less than 8, and even more preferably less than 6. This is because the smaller the aspect ratio of the expanded test specimen, the more likely it is that a sealant manufactured using the water-swellable waterstop composition of the present invention will expand in the thickness direction. The aspect ratio of the expanded test specimen may be, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0, and may be greater than or equal to any of the values ​​exemplified here but less than any of them.

[0040] 1.3.Applications The water-swellable water-stopping composition of this embodiment is preferably used as a sealing material. Sealing materials produced using the water-swellable water-stopping composition of this embodiment can be suitably used for applications such as civil engineering water-stopping materials for shield tunneling segments, box culverts, flumes (steel frames, benches), Hume pipes, manhole joints, reservoirs, water channels, pools, and the like, and concrete joint waterstops; construction-related water-stopping materials for various water tanks, H-beam surroundings, and various joints; and housing equipment-related water-stopping materials for purified water tanks, water receiving tanks, and unit baths. Furthermore, sealing materials produced using the water-swellable water-stopping composition of this embodiment can exhibit sufficient water-stopping effects even when used in the joints of concrete products used in waterways for not only freshwater but also seawater.

[0041] 2. Water-swellable water-stopping composition and method for producing molded article The water-swellable water-stopping composition of this embodiment can be produced by kneading the necessary components. Furthermore, a molded article using the water-swellable water-stopping composition can be produced by molding the water-swellable water-stopping composition by pressing or the like. This molded article can be used as a sealing material.

[0042] Apparatuses for kneading the compound include conventionally known kneading apparatuses such as mixers, Banbury mixers, kneader mixers, and two-roll mills. Apparatuses for molding the kneaded compound include conventionally known molding apparatuses such as press molding, extrusion molding, and calendar molding. The shape of the molded product may be designed to be, for example, a sheet or tape, depending on the application. [Example]

[0043] The present invention will be described in more detail below with reference to examples, in which the amount of each substance used is expressed in parts by mass.

[0044] 1. Preparation of water-swellable water-stopping composition The components listed in Tables 1 to 5 were kneaded for 10 minutes at 100°C using a 3L pressure kneader (manufactured by Moriyama Co., Ltd., model: DS3-10MWB-S) to obtain water-swellable waterproof compositions for Examples and Comparative Examples. The amount of each substance used in the tables is in parts by mass unless otherwise specified.

[0045] [Table 1]

[0046] [Table 2]

[0047] [Table 3]

[0048] [Table 4]

[0049] [Table 5]

[0050] Details of each component in the table are as follows: The numerical value in parentheses after the name of the fibrous organic or inorganic compound in the table indicates the average length of the fiber. <Rubber and / or elastomer> EPDM rubber (Sumitomo Chemical Co., Ltd., "Esprene 505") Butyl rubber (JSR Corporation, "Butyl 268") <Thermoplastic resin> LDPE: Ube Maruzen Polyethylene Co., Ltd. "J5019" <Water absorbent resin> Acrylic acid polymer partially cross-linked with sodium salt: "Aqualic CS-6S" manufactured by Nippon Shokubai Co., Ltd. Sodium carboxymethylcellulose (CMC-Na): Hayashi Pure Chemical Industries, Ltd. <Fibrous organic compounds> Pulp fiber, average length 2 mm: "Neofiber NS-10" manufactured by Oji Seitai Co., Ltd. Polyarylate fiber, average length 2 mm: "Vectran UM1580" manufactured by Kuraray Co., Ltd. Para-aramid fiber, average length 0.25, 0.5, 3, 10, 12 mm: Twaron Short Cut Fiber manufactured by Teijin Limited <Fiber-like inorganic compounds> Alumina fiber, average length 0.5, 7, 10, 11 mm: Nichibi Co., Ltd. "Nichibi ALF" <Silica and clay minerals> Silica: Nipsil VN3 manufactured by Tosoh Silica Corporation Sepiolite: Miraclay P150 manufactured by Omi Mining Co., Ltd. Bentonite: "Bengel" manufactured by Hojun Co., Ltd. <Other inorganic compounds> Calcium carbonate: TA-044, manufactured by Chichibu Lime Industry Co., Ltd.

[0051] 2. Evaluation The water-swellable waterproofing compositions obtained in the examples and comparative examples were processed into sheet-shaped molded bodies 2 mm thick using a press (temperature: 80°C, time: 1 minute), and the obtained molded bodies were used to perform the various evaluations shown below.

[0052] 2.1. Water swelling In accordance with JIS K-6258, a test piece 2 mm thick, 30 mm wide, and 30 mm long was immersed in water at 23°C for 3 days, and the volume change rate before and after immersion was calculated using the following formula. The volume change rate before and after immersion was considered to indicate the amount of water absorbed by the test piece, i.e., the amount of volume change, and the water swelling property was evaluated according to the following evaluation criteria. Volume change rate (%) = {((cd)-(ab)) / (ab)} x 100 a: Weight in the air before immersion, b: Weight in water before immersion c: Weight in air after immersion in water, d: Weight in water after immersion in water

[0053] (Evaluation criteria) ◎: Volume change rate is 300% or more ○: Volume change rate is 200% or more but less than 300% △: Volume change rate is 100% or more but less than 200% ×: Volume change rate is less than 100%

[0054] 2.2. Shape retention after swelling in water A test piece having a thickness of 2 mm, a width of 30 mm and a length of 30 mm was immersed in water at 23°C for 3 days, and then the shape retention of the test piece was visually observed and evaluated according to the following evaluation criteria. (Evaluation criteria) ◎: No cracks were observed in the test piece after swelling with water ○: Cracks were observed in the test piece after swelling in water, but it did not crumble when taken out of water. ×: The test piece collapses when taken out of the water after swelling with water

[0055] 2.3. Water swelling in the thickness direction A test piece 2 mm thick, 30 mm wide, and 30 mm long was immersed in water at 23°C for 3 days to expand, and the aspect ratio of the expanded test piece was measured. Specifically, the aspect ratio after water expansion was determined by dividing the average dimension of the four horizontal sides of the expanded test piece by the maximum vertical dimension. ◎: Aspect ratio after water expansion is less than 6 ○: Aspect ratio after water expansion is 6 or more and less than 8 △: Aspect ratio after water expansion is 8 or more and less than 10 ×: Aspect ratio after water expansion is 10 or more

[0056] 2.4. Flexibility Two SUS304 plates, each 1 mm thick, 25 mm wide, and 100 mm long, were prepared with double-sided tape attached and placed side by side, 3 mm apart in the longitudinal direction. A test piece, 2 mm thick, 10 mm wide, and 100 mm long, was attached across the two SUS304 plates, and the test piece was bent in the opposite direction from the attached surface. The angle at which the test piece cracked was measured, and the flexibility was evaluated according to the following criteria. The larger the angle at which the crack appeared, the better the flexibility. ◎: No cracks even at a 180 degree angle ○: Cracks occur at angles between 160 degrees and 180 degrees △: Cracks occur at angles between 140 degrees and 160 degrees ×: Cracks occur at angles less than 140 degrees

Claims

1. Contains rubber, The rubber composition contains 45 to 150 parts by mass of a water-absorbent resin and 12 to 110 parts by mass of a fibrous compound relative to 100 parts by mass of the rubber, The rubber composition contains 12 to 150 parts by mass of silica and / or clay mineral per 100 parts by mass of the rubber, the rubber is at least one selected from butyl rubber and ethylene-propylene-diene rubber, The water-swellable water-stopping composition includes at least one absorbent resin selected from the group consisting of partial sodium salts of acrylic acid polymers and crosslinked products thereof, partial sodium salts of acrylic acid graft polymers and crosslinked products thereof, and sodium carboxymethylcellulose.

2. 2. The water-swellable water-stopping composition according to claim 1, wherein the average length of the fibrous compound is 0.5 to 10 mm.

3. The water-swellable waterstop composition of claim 1 , wherein the fibrous compound comprises a fibrous organic compound.

4. The water-swellable water-stopping composition according to claim 1, wherein a test piece obtained by molding the water-swellable water-stopping composition into a flat plate having a thickness of 2 mm, a width of 30 mm, and a length of 30 mm is immersed in water at 23°C for 3 days to expand the expanded test piece, and the aspect ratio after expansion in water is less than 6.

5. The water-swellable water-stopping composition according to any one of claims 1 to 4, which is used as a sealing material.

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