Water-swellable waterstop composition

Abstract

To provide a water-swellable composition that is superior in terms of water swellability, shape retention after water swelling, adhesion resistance, and deformability.SOLUTION: The present invention provides a water-swellable waterstop composition which includes 10 to 300 pts.mass of an inorganic compound and 10 to 300 pts.mass of a plasticizer relative to 100 pts.wt. of a rubber A that is an epichlorohydrin-based rubber copolymerized with an ethylene oxide component.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a water-swellable waterstop composition capable of manufacturing a sealing material.

Background Art

[0002] In the field of civil engineering and architecture, water-swellable waterstop materials formed into tape-like or film-like shapes are used for the purpose of preventing water leakage and stopping water at the joints of various pipes such as tunnel segments, underground sewer pipes, and U-shaped grooves for water supply and drainage.

[0003] For example, Patent Document 1 discloses a vulcanizing composition containing a rubber component composed of an epichlorohydrin-based polymer rubber and a styrene-butadiene rubber (SBR), magnesium oxide, a sulfenamide-based compound, sulfur and / or an active sulfur-releasing organic vulcanization accelerator, a thiourea-based compound, and further, if necessary, a water-absorbing substance.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A sealing material manufactured using a water-swellable waterstop composition exhibits waterstop performance by absorbing water and expanding in volume when it comes into contact with water. Such a sealing material is desired to have both excellent expansibility due to water absorption and excellent shape stability such that it does not disintegrate even when it swells after absorbing water.

[0006] In addition, since the shape of the water-swellable composition of Patent Document 1 is tape-like or sheet-like, it has been difficult to freely deform and construct the water-swellable composition according to the shape when the shape of the waterstop target location is complex.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a water-swellable composition excellent in water-swellability, shape retention after water swelling, non-adhesiveness, and deformability.

Means for Solving the Problems

[0008] The inventors of the present invention intensively studied to solve the above problems. As a result, they found that the above problems can be solved by using a composition with a specific formulation, and thus completed the present invention.

[0009] That is, the present invention is as follows [1] A water-swellable waterstop composition containing 10 to 300 parts by mass of an inorganic compound and 10 to 300 parts by mass of a softening agent with respect to 100 parts by weight of rubber A, which is an epichlorohydrin rubber copolymerized with an ethylene oxide component. [2] The water-swellable waterstop composition according to [1], further containing 300 parts by mass or less of a water-absorbing resin other than rubber A with respect to 100 parts by weight of the rubber A. [3] The water-swellable waterstop composition according to [1] or [2], wherein the inorganic compound contains silica. [4] The water-swellable waterstop composition according to [1] or [2], wherein the softening agent contains at least one of an ester plasticizer or an ether plasticizer. [5] The water-swellable waterstop composition according to any one of [1] to [4], used as a sealing material.

Effects of the Invention

[0010] According to the present invention, it is possible to provide a water-swellable waterstop composition capable of manufacturing a sealing material excellent in water-swellability, shape retention after water swelling, non-adhesiveness, and deformability.

Modes for Carrying Out the Invention

[0011] Hereinafter, the modes for carrying out the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0012] 1. Water-swellable waterstop composition The water-swellable waterstop composition of the present embodiment contains 10 to 300 parts by mass of an inorganic compound and 10 to 300 parts by mass of a softening agent with respect to 100 parts by weight of rubber A (hereinafter also referred to as "rubber A"), which is an epichlorohydrin-based rubber copolymerized with an ethylene oxide component. Such a water-swellable composition is a composition excellent in deformability and can be used as a putty that is easy to use according to the shape. That is, the composition can be provided as a putty-like water-swellable composition.

[0013] <Epichlorohydrin-based rubber copolymerized with an ethylene oxide component> Examples of the epichlorohydrin-based rubber A copolymerized with an ethylene oxide component include epichlorohydrin-ethylene oxide copolymer and epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer. These rubbers A may be used alone or in combination of two or more.

[0014] Rubber A contains, for example, 70 to 95 mol% of an ethylene oxide component, preferably 80 to 90 mol%. When the ethylene oxide component is within this range, the water-swellability is improved. Further, rubber A may contain, for example, 5 to 30 mol%, preferably 10 to 20 mol% of an epichlorohydrin component, and 0 to 10 mol%, preferably 0 to 8 mol%, more preferably 0 to 6 mol% of an allyl glycidyl ether component.

[0015] The water-swellable waterstop composition preferably contains 15 to 55% by mass of rubber A with respect to 100% by mass of the water-swellable waterstop composition. Specifically, the content of rubber A is, for example, 15, 18, 20, 25, 30, 35, 40, 45, 50, 53, 55% by mass, and may be within the range between any two of the values exemplified herein.

[0016] <Water-absorbing resin> A water-absorbing resin, also called SAP (Super Absorbent Polymer), is a polymer that has a water absorption performance of absorbing 300 to 2000 times its own weight of water and a water retention performance of holding the water in a very stable state. The water-absorbing resin is not particularly limited. For example, acrylic acid polymer partial sodium salts and their cross-linked products, acrylic acid graft polymer partial sodium salts and their cross-linked products, starch-acrylic acid graft polymer salts and their cross-linked products, saponified products of vinyl acetate-acrylic acid ester copolymers and their cross-linked products, 2-acrylamido-2-methylpropanesulfonic acid-acrylic acid copolymer salts and their cross-linked products, etc. of acrylic polymers; carboxymethyl cellulose sodium, carboxymethyl cellulose ammonium and other cellulose compounds; polyalkylene oxides, alkylene oxide polymers such as modified polyalkylene oxides; hydrolysis products of starch-acrylonitrile graft polymers, hydrolysis products of acrylonitrile copolymers or acrylamide copolymers or their cross-linked products, cross-linked products of cationic monomers, cross-linked isobutylene-maleic acid copolymers, etc. The water-absorbing resin may be used alone or in combination of two or more. In this specification, the "water-absorbing resin" is a water-absorbing resin other than Rubber A and does not contain Rubber A.

[0017] Among these, the water-absorbing resin preferably contains an alkylene oxide polymer and may be an alkylene oxide polymer. By using such a water-absorbing resin, the water swelling property tends to be further improved.

[0018] The content of the water-absorbing resin is, for example, 0 to 300 parts by mass, preferably 1 to 200 parts by mass, and more preferably 5 to 50 parts by mass with respect to 100 parts by mass of Rubber A. The water-swellable water-stopping composition may contain 300 parts by mass or less of a water-absorbing resin other than Rubber A with respect to 100 parts by mass of Rubber A. Specifically, the content of the water-absorbing resin is, for example, 0, 1, 5, 10, 20, 30, 40, 50, 55, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 300 parts by mass with respect to 100 parts by mass of Rubber A, and it may be within the range between any two of the numerical values exemplified here.

[0019] <Inorganic compound> The inorganic compound preferably contains silica, and more preferably the inorganic compound is silica. Silica is a general term for silicon dioxide or substances composed of silicon dioxide, and may also be called silicic anhydride, silicic acid, or silicon oxide in addition to the name silica. Silica takes various forms (crystal polymorphs) depending on conditions such as pressure and temperature, and is roughly classified into two types: crystalline silica and amorphous silica.

[0020] The water-swellable water-stopping composition has particularly good water-swellability by containing 10 parts by mass or more of silica with respect to 100 parts by mass of Rubber A.

[0021] The inorganic compound may include inorganic compounds other than silica. Such inorganic compounds include, for example, metal oxides such as calcium carbonate, alumina, aluminosilicate, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, aluminum hydroxide, ferrites; hydrous inorganic substances such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, hydrotalcite; metal carbonates (excluding calcium carbonate) such as basic magnesium carbonate, magnesium carbonate, zinc carbonate, strontium carbonate, barium carbonate; calcium salts such as calcium sulfate, calcium silicate; diatomaceous earth, dacite, barium sulfate, mica, activated clay, imogolite, 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, pearlite, pitchstone, diatomaceous earth, dehydrated sludge, boron, glass fiber, sodium tetraborate hydrate (borax), clay minerals, and the like.

[0022] The content of the inorganic compound is 10 to 300 parts by mass, preferably 50 to 230 parts by mass, and more preferably 70 to 210 parts by mass with respect to 100 parts by mass of rubber A. When the content of the inorganic compound is less than 10 parts by mass, the non-adhesiveness deteriorates. On the other hand, when the content of the inorganic compound exceeds 300 parts by mass, the deformability deteriorates. Specifically, the content of the inorganic compound is, for example, 10, 20, 30, 40, 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 parts by mass with respect to 100 parts by mass of rubber A, and it may be within the range between any two of the values exemplified here.

[0023] <Softening agent> The softening agent is not particularly limited, and examples thereof include rapeseed oil, cottonseed oil, palm oil, coconut oil, peanut oil, tall oil, pine tar, mineral oil, process oil (paraffin-based oil, naphthene-based oil, and aromatic-based process oil), ester-based plasticizer, ether-based plasticizer, ether-ester-based plasticizer, and the like. The softening agent may be used alone or in combination of two or more. Among these, it is preferable to contain at least one of an ester-based plasticizer or an ether-based plasticizer.

[0024] Examples of the ester-based plasticizer include phthalic acid esters such as di(2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP); aliphatic dibasic acid esters such as di(2-ethylhexyl) adipate (DEHA) and di(2-ethylhexyl) sebacate (DEHS); trimellitic acid esters such as tri(2-ethylhexyl) trimellitate (TEHTM) and triisononyl trimellitate (TINTM); phosphate esters such as triisopropylphenyl phosphate; adipic acid polyesters such as adipic acid polyester; and others such as maleic acid ester, fumaric acid ester, citric acid ester, oleic acid ester, ricinoleic acid ester, stearic acid ester, glycolic acid ester, and the like.

[0025] Examples of the ether-based plasticizer include bis[2-(2-butoxyethoxy)ethyl] adipate (DBEEA), polyethylene glycol ester, and the like.

[0026] The content of the softening agent is 10 to 300 parts by mass, preferably 50 to 250 parts by mass, and more preferably 100 to 200 parts by mass with respect to 100 parts by mass of Rubber A. When the content of the softening agent is less than 10 parts by weight, the deformability deteriorates. On the other hand, when the content of the softening agent exceeds 200 parts by weight, the non-adhesiveness and shape stability deteriorate. Specifically, for example, the content of the softening agent is 10, 20, 30, 40, 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 parts by mass with respect to 100 parts by mass of Rubber A, and it may be within the range between any two of the numerical values exemplified here.

[0027] <Other additives> In addition to the above components, the water-swellable composition of the present embodiment may, if necessary, be used in combination with rubbers other than Rubber A or thermoplastic elastomers, and various additives such as crosslinking (vulcanizing) agents, crosslinking (vulcanizing) aids, antioxidants, ultraviolet absorbers, tackifier resins, lubricants, dispersants, fibrous compounds, etc. used for rubbers or thermoplastic elastomers.

[0028] <Crosslinking agent and crosslinking accelerator> When the water-swellable waterstop composition of the present embodiment is in a mode that does not require crosslinking (vulcanizing) treatment, it is preferably substantially free of a crosslinking agent (vulcanizing agent) and / or a crosslinking accelerator (vulcanizing accelerator). Further, when it is in a mode that requires crosslinking treatment, it may contain a crosslinking agent and / or a crosslinking accelerator.

[0029] Here, the crosslinking agent is not particularly limited as long as it can crosslink rubber. For example, sulfur-based compounds such as sulfur and polysulfide; oxime compounds such as p-quinonedioxime and p,p'-dibenzoylquinone oxime; organic peroxide-based compounds such as t-butyl hydroperoxide, acetylacetone peroxide, and cumene hydroperoxide, etc. can be mentioned. Note that crosslinking agents, particularly sulfur-based compounds such as sulfur and polysulfide, etc. can also be regarded as acting as crosslinking accelerators.

[0030] Moreover, the crosslinking accelerator is not particularly limited as long as it is a crosslinking accelerator used for promoting the crosslinking of rubber. For example, thiuram compounds such as tetramethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, dipentamethylenethiuram tetrasulfide; thiazole compounds such as 2-mercaptobenzothiazole and dibenzothiazole disulfide; carbamate compounds such as zinc dimethyldithiocarbamate and zinc dibutyldithiocarbamate; aldehydeamine compounds such as n-butylaldehyde aniline; sulfenamide compounds such as N-cyclohexyl-2-benzothiazylsulfenamide; guanidine compounds such as diorthotolylguanidine and diorthonitrileguanidine; thiourea compounds such as thiocarbanilide, diethylthiourea, trimethylthiourea, ethylene thiourea; compounds such as zinc oxide. Note that crosslinking accelerators, especially thiourea compounds, etc. can also be regarded as acting as crosslinking agents.

[0031] In the case of a mode that does not require crosslinking treatment, "substantially free of" a crosslinking agent, etc. means that both the crosslinking agent and the crosslinking accelerator are at least preferably less than 0.1 part by mass, more preferably less than 0.01 part by mass, and still more preferably less than 0.005 part by mass with respect to 100 parts by mass of rubber A. Also, the lower limit value of the content of the crosslinking agent and the crosslinking accelerator is not particularly limited, but can be set below the detection limit. In one aspect, the total content of the crosslinking agent and the crosslinking accelerator is preferably less than 0.11 part by mass with respect to 100 parts by mass of rubber A.

[0032] The content of rubber or thermoplastic elastomer other than rubber A is, for example, 0 to 40 parts by mass, preferably 0 to 10 parts by mass with respect to 100 parts by mass of rubber A. Examples of the rubber other than rubber A include styrene-butadiene rubber (SBR).

[0033] <Method for producing and uses of water-swellable composition> The water-swellable composition of this embodiment can be produced by kneading the necessary components. Further, a molded article using the water-swellable composition can be produced by molding the water-swellable composition by pressing or the like. This molded article can be used as a sealing material.

[0034] Examples of the apparatus for kneading the formulation include conventionally known kneading apparatuses such as mixers, Banbury mixers, kneader mixers, and two-roll mills. Examples of the apparatus for molding the kneaded formulation include conventionally known molding apparatuses such as press molding, extrusion molding, and calender molding. Further, the shape of the molded article may be appropriately designed according to the application, such as in the form of a sheet or a tape.

[0035] Further, the water-swellable waterstop composition of this embodiment can have appropriate deformability as putty and may be used as a putty-like sealing material.

Examples

[0036] Hereinafter, the present invention will be described in more detail with reference to examples. In the following, the unit of the amount of each substance used is parts by mass.

[0037] 1. Preparation of water-swellable waterstop composition The water-swellable compositions of the examples and comparative examples were obtained by kneading the components shown in Table 1 at 100 ° C for 10 minutes using a 3 L pressure kneader (manufactured by Moriya Co., Ltd., model: DS3-10MWB-S). The unit of the amount of each substance shown in Table 1 is parts by mass unless otherwise specified.

[0038]

Table 1

[0039]

Table 2

[0040]

Table 3

[0041] Details of each component in Table 1 are as follows. <Epichlorohydrin rubber> · Rubber a-1: Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer: manufactured by Osaka Soda Co., Ltd., "Epion 301" · Rubber a-2: Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer: manufactured by Osaka Soda Co., Ltd., "Epichlomer DG" · Rubber a-3: Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer: manufactured by Osaka Soda Co., Ltd., "Epichlomer CG102" · Rubber b-1: Epichlorohydrin polymer: manufactured by Osaka Soda Co., Ltd., "Epichlomer H" <Water-absorbing resin> · Modified polyalkylene oxide: manufactured by Sumitomo Seika Chemicals Co., Ltd., "Aquacoke TWB" · Acrylic acid polymer partial sodium salt cross-linked product: manufactured by Nippon Shokubai Co., Ltd., "Aquaric CS-6S" <Inorganic compound> · Silica: manufactured by Tosoh Silica Corporation, "Nipsil VN3" · Calcium carbonate: manufactured by Chichibu Cement Co., Ltd., "TA-044" <Softening agent> · Polyether ester plasticizer manufactured by ADEKA Corporation, "Adekaser RS-700" · Process oil: manufactured by Idemitsu Kosan Co., Ltd., "Diana Process Oil NP-24"

[0042] 2. Evaluation The following various measurements and evaluations were performed on the water-swellable waterstop compositions obtained in the examples and comparative examples.

[0043] <Deformability (softness)> The water-swellable composition was processed into a sheet-shaped molded body with a thickness of 2 mm using a press machine (temperature: 80 °C, time: 1 minute). Using the obtained molded body (test piece 1), the softness of test piece 1 was measured at a load of 150 g and a temperature of 21 °C in accordance with JIS A5752. A specified cone was vertically penetrated into test piece 1, and the penetration depth was measured in units of 0.1 mm. Then, based on the penetration depth, the deformability was determined according to the following criteria. ◎: 60 [1 / 10 mm] or more ○: 50 [1 / 10 mm] or more and less than 60 [1 / 10 mm] △: 40 [1 / 10 mm] or more and less than 50 [1 / 10 mm] ×: less than 40 [1 / 10 mm]

[0044] <Non-adhesiveness> Wearing latex rubber gloves, the mass of the adherents on the gloves after grasping 100 g of the water-swellable composition 10 times was measured, and the mass of the adherents was calculated based on the following formula. Then, based on the mass of the adherents, the non-adhesiveness was determined according to the following criteria. Note that the lower the non-adhesiveness, the easier it is to process. Mass of adherents (g) = (mass of the gloves after grasping 100 g of the water-swellable composition 10 times) - (mass of the original gloves) ◎: less than 0.02 [g] ○: 0.02 [g] or more and less than 0.05 [g] △: 0.05 [g] or more and less than 0.10 [g] ×: 0.10 [g] or more

[0045] <Water-swellability> In accordance with JIS K-6258, 10 g of the water-swellable composition was formed into a spherical molded body (test piece 2), immersed in water at 23 °C for 7 days, and the volume change rate before and after immersion was calculated using the following formula. Assuming that the volume change rate before and after immersion indicates the water supply amount of test piece 2, that is, the volume change amount, the water-swellability was evaluated according to the following evaluation criteria. Volume change rate (%) = ((c - d) - (a - b)) / (a - b) × 100 a: Air mass before water immersion, b: Water mass before water immersion c: Air mass after water immersion, d: Water mass after water immersion (Evaluation Criteria) ◎: Volume change rate is 150% or more ○: Volume change rate is 130% or more and less than 150% △: Volume change rate is 110% or more and less than 130% ×: Volume change rate is less than 110%

[0046] <Shape Retention after Water Swelling> A 5 g water-swellable composition was molded into a spherical molded body (Test Specimen 3), immersed in water at 23°C for 7 days, and the shape retention of the test specimen was visually observed and evaluated according to the following evaluation criteria. (Evaluation Criteria) ◎: No cracks are observed in Test Specimen 3 after water swelling ○: Cracks are observed in Test Specimen 3 after water swelling, but it does not collapse even when taken out of water △: Cracks are observed in Test Specimen 3 after water swelling, and it collapses when taken out of water ×: Test Specimen 3 after water swelling has collapsed in water

Claims

1. A water-swellable waterstop composition comprising 10 to 300 parts by mass of an inorganic compound and 10 to 300 parts by mass of a softening agent with respect to 100 parts by weight of rubber A, which is an epichlorohydrin rubber copolymerized with an ethylene oxide component.

2. The water-swellable waterstop composition according to claim 1, further comprising 300 parts by mass or less of a water-absorbing resin other than the rubber A with respect to 100 parts by weight of the rubber A.

3. The water-swellable waterstop composition according to claim 1 or claim 2, wherein the inorganic compound contains silica.

4. The water-swellable waterstop composition according to claim 1 or claim 2, wherein the softening agent contains at least one of an ester plasticizer or an ether plasticizer.

5. The water-swellable waterstop composition according to claim 1 or claim 2, which is used as a sealing material.

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