JPH0453889B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to water-swellable foam sealants, and in particular water-swellable foams that absorb water and expand at a high speed, have low expansion pressure, and shrink less even when dried after being expanded. This relates to sealants. The sealing material of the present invention exhibits sufficient water-stopping performance in the field of civil engineering and construction, and is particularly effective as a water-stopping material for above-ground structures. [Prior art and problems] Conventionally, water-swellable sealants have been made by adding water-absorbing substances such as sodium polyacrylate, starch, carboxymethyl cellulose, and polyethylene glycol to rubber or plastic to impart water-swellability. However, all of these shrink to almost their original state when dried.
Further, in these water-swellable sealing materials, the water-swelling rate gradually decreases because the water-absorbing substance becomes water-soluble and is eluted. Furthermore, when used as a water stop material for joints of concrete, the expansion pressure caused by water swelling causes the concrete to crack or break at an early stage, so there are various restrictions on its use. [Means for Solving the Problems] The present inventors have completed the present invention as a result of intensive research in order to improve the above problems. That is, the water-swellable foam sealant of the present invention is
It is characterized in that it contains a water-swellable substance ( ), a hydraulic substance ( ), and a rubber ( ) as essential components, and is foamed with a foaming agent. In the present invention, the water-swellable substance () can be selected as appropriate depending on the intended use of the sealant, but
Those that can be kneaded with rubber and/or elastomers (hereinafter referred to as rubbers) are preferred, such as water-swellable urethane resins, carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol,
Hydroxyethyl cellulose, methyl cellulose, etc. can be used alone or in combination, and in addition, what is usually called a water-absorbing resin can also be used. Among them, water-swellable urethane resins are preferred. The water-swellable urethane resin is preferably a paste or an elastomer when mixed with a hydraulic substance, and a paste is particularly preferred. Examples of pasty water-swellable urethane resins include resins obtained by reacting a water-swellable polyurethane prepolymer containing terminal isocyanate groups with water and/or a curing agent. The water-swellable polyurethane prepolymer containing terminal isocyanate groups may have, for example, a hydroxyl equivalent of
Examples include prepolymers having a propylene oxide/ethylene oxide ratio of 7/3 to 0/10 obtained by reacting 400 to 6000 ethylene oxide/propylene oxide random/block polymerized polyoxyalkylene glycol with an organic diisocyanate in a conventional manner. The prepolymer can be partially cured by a conventional method with water or an amine-based or polyol-based curing agent to form a water-swellable urethane resin in the form of a paste. Curing may be carried out using a combination of water and a curing agent. As a curing agent, 4,4'-methylene-bis-2-chloroaniline, 1,4-butanediol, hydroquinone-bis-(β-hydroxy)
Ether, resorcinol bis-(β-hydroxy) ether, 1,2-bis-(2-aminophenolthio)ethane, trimethylene glycol di-p-aminobenzoate, etc. can be used alone or in combination. In addition, what is usually referred to as water-absorbing resin here includes molecules containing a carboxyl group or a group that can be induced into a carboxyl group, such as a carboxyl group, a carboxylate, a carboxylic acid amide, a carboxylic acid imide, and a carboxylic acid anhydride. The main component is one or two α,β-unsaturated compounds, and if necessary, other α,β-unsaturated compounds are added and polymerized, or these are further modified with isocyanates, etc. can be mentioned. Examples of such water-absorbing resins include starch/acrylic acid graft copolymers, salts of styrene-maleic anhydride copolymers, crosslinked products of sodium polyacrylate, crosslinked products of polyvinyl alcohol/maleic anhydride reactants, and vinyl Known super absorbent polymers such as saponified products of esters/ethylenically unsaturated carboxylic acids or derivatives thereof can be used. Further, in the present invention, as the hydraulic substance (2), hydraulic cement is preferable, and in addition, gypsum and latent hydraulic substances can also be used. Further, it is more preferable to add a cement-based quick hardening agent to the hydraulic material. Here, hydraulic cement is usually white,
Various types of early-strength Portland cement, special cements such as blast furnace cement, colloidal cements classified by particle size, etc. can be used as appropriate. As cement-based quick hardening agents, calcium aluminate-based inorganic substances, namely 3CaO・AI ₂ O ₃ , CaO・
Al ₂ O ₃ , 12CaO・7Al ₂ O ₃ , CaO・2Al ₂ O ₃ , CaO・
Calcined products and molten mixtures of CaO and Al ₂ O ₃ such as 6Al ₂ O ₃ ,
Alternatively, calcium sulfoaluminate mixed with gypsum or the like may be used, and commercially available products include Denka ES (trade name, manufactured by Denki Kagaku Co., Ltd.). Rubber used in the present invention includes natural rubber,
There are synthetic rubbers and recycled rubbers, such as natural rubber,
It is selected from among styrene butane diene rubber, isoprene rubber, acrylonitrile butadiene rubber, chloroprene rubber, ethylene propylene terpolymer, butyl rubber and recycled rubber thereof, depending on the use and purpose. In the present invention, an elastomer can be used in place of or together with the above rubber, and such elastomers include polyurethane, polyolefin, polystyrene, and the like. As the blowing agent used in the present invention,
N,N'-dinitrosopentamethylenetetramine,
Examples include organic blowing agents such as azodicarboxinamide and p,p'-oxybis(benzenesulfonylhydrazide), and microcapsule type blowing agents. Further, a urea-based or organic acid-based foaming aid may be used as appropriate. In addition, in the case of the present invention, adding a substance that causes cross-linking between molecules makes it easier to manufacture the foam,
This is preferred because it improves the physical properties of the foam. The substances that cause cross-linking between molecules used in the present invention include water-swellable substances and substances that can cause cross-linking between molecules of rubber, such as sulfur, sulfur chloride, organic Rubber vulcanizing agents such as peroxides, organic sulfur compounds, metal oxides, alkylphenol resins, polythiol compounds, polyamine compounds, azo compounds, etc. can be used. Particular preference is given to crosslinking with sulfur and organic peroxides. The sulfur is preferably powdered sulfur, and suitable organic peroxides include benzoyl peroxide, dicumyl peroxide, methyl ethyl ketone peroxide, lauryl peroxide, cyclohexanone peroxide, t-butyl perbenzoate, and t-butyl perbenzoate.
-butyl hydroperoxide, t-butylbenzene peroxide, cumene hydroperoxide, t
-butyl peroctoate, etc. Suitable organic sulfur compounds include tetramethylthiuram disulfide (TT), N,N'-dithiobismorpholine, and the like. Suitable metal oxides include zinc white, magnesia, litharge, and the like. Suitable alkylphenol resins include alkylphenol formaldehyde resins containing 7 to 10% methylol groups. Suitable polythiol compounds include trimethylolpropane trithioglycolate, trimethylolpropane tri(3-mercaptopropionate), glycol dimercaptopropionate,
Examples include glycol dimercaptoacetate, pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetrathioglycolate, dipentaerythritol hexa(3-mercaptopropionate), and the like. Suitable polyamine compounds include aldehyde-amine condensates, guanidines, and the like. Suitable azo compounds include azobisisobutyronitrile, 2-t-butylazo-2-cyano-
4-methylpentane, 4-t-butylazo-4-
Examples include cyano-valeric acid. The above crosslinking agents can be used alone or in combination of two or more, and the appropriate amount is 0.5 to 10 parts per 100 parts (by weight, the same applies hereinafter) of the rubber (). be. The content of the water-swellable substance () in the water-swellable foam sealant of the present invention is preferably 20 to 250 parts, particularly 60 to 180 parts, per 100 parts of the rubber (). It is preferable to use Further, the content of the hydraulic substance ( ) can be appropriately selected in relation to the water swelling rate and physical properties of the water-swellable foam sealant of the present invention, but the content of the hydraulic substance ( ) 20 to 300 copies are preferred;
More preferably 50 to 150 parts. When hydraulic substances and other inorganic additives are added, the foam can be manufactured more easily if the total amount is smaller, but the shrinkage during drying increases, so please adjust the amount accordingly depending on the purpose of use. It's good to choose. Furthermore, when a cement-based quick hardening agent is added to the above-mentioned hydraulic substance (), the amount added is preferably 30 to 150 parts per 100 parts of the hydraulic substance (), particularly 50 parts.
~100 parts is preferred. Furthermore, the total amount of the hydraulic substance (), inorganic additive, and cement-based quick hardening agent is preferably 20 to 500 parts, especially with respect to 100 parts of the total amount of the water-swellable substance () and the rubber (). 100 to 300 parts is preferred. The amount of the blowing agent to be added can be selected as appropriate by considering the type of blowing agent used, the specific gravity of the foam, the water expansion rate, etc., but it is 0.3 to 20 parts of the blowing agent per 100 parts of the rubber (). is preferred. The water swelling rate of the sealant of the present invention is 20 to 350% (by volume), preferably 40 to 250% (by volume). The water-swellable foam sealing material of the present invention can be molded by an appropriate method and used as a sealing material, but it can be compounded using an ordinary rubber kneading machine such as a roll, kneader, or Banbury mixer, and then molded using an extrusion molding machine or a press molding machine. It is preferable to mold by. A cross-linking agent is added to the above water-swellable substances () and rubbers (), and general foaming agents, foaming aids, vulcanization accelerators, vulcanization aids, softeners, anti-aging agents, adhesives, etc. A rubber compounding agent is appropriately selected and blended, and a hydraulic substance (2), a cement quick hardening agent, an inorganic additive, etc. are added, and then kneading is carried out using a kneading roll, a Banbury mixer, or the like. After molding, this is subjected to pressing, foaming, and vulcanization treatment (usually at 120°C or higher) to obtain a water-swellable foam sealant. The vulcanization treatment is not limited to heat vulcanization, steam vulcanization, or hot air vulcanization, but may also be natural vulcanization, hot water vulcanization, or cold vulcanization. When a cross-linking agent is used, water-swellable foam sealants are treated with water-swellable substances ().
It is characterized by the fact that the rubber and rubber () are integrally cross-linked with each other. [Effects of the Invention] The water-swellable foam sealing material of the present invention has excellent water-swellability, excellent mechanical properties, and water-stopping properties, and can be used in a wide range of applications as water-stopping materials, packing materials, and the like. The water-swellable foam sealing material of the present invention forms a skeleton (matrix) of hydraulic material after absorbing water, so it has good stability in water and shrinks little even when dried. The water-swellable foam sealant of the present invention has a low expansion pressure when it swells with water, so when used to stop water at concrete joints, it does not cause problems such as cracking of the concrete, and can be applied to relatively thin concrete. It can also be used for joints. Furthermore, the same degree of swelling can be obtained even with seawater as with freshwater. [Example] Hereinafter, the present invention will be explained in more detail with reference to Examples. Examples 1 to 4 and Comparative Example 1 The formulations shown in Table 1 (unit: parts by weight) were kneaded using a 20 cm open roll to create blended products 1 to 5.

【table】

[Table] Press these blended products at 140℃ for 10 minutes,
A sheet with a thickness of mm was obtained. The sheet was subjected to a tensile test (measurement method: JIS K6301), specific gravity, swelling rate when immersed in water (volume change rate after 12 days of immersion), swelling rate and swelling pressure after 21 days of drying. The results are shown in Table 2. Comparative Example 1 was a compounded product that did not use a hydraulic substance or a blowing agent.

[Table] Example 5 and Comparative Example 2 The blended product used in Example 1 was pressed at 140°C for 10 minutes to obtain a sheet of approximately 2 mm, which was cut into rings and the water pressure resistance was measured. For comparison, similar measurements were conducted using a foam manufactured by Company S. The shape of the ring is 12 cm in inner diameter, 2 cm in width, and 2 mm in thickness.
As for the product from Company S, a long piece with a width of 2 cm was used to make the same shape. In addition, to measure the water pressure resistance, place a ring of the above dimensions between the spacers 3.0 mm apart, act as a seal when inflated, and use a device that can measure the water pressure resistance until water leaks when water pressure is applied with a pump. The temperature was increased by 1 kg/cm ² and maintained at that pressure for 5 minutes, and the highest pressure before water leakage was defined as the water resistance pressure. The results are shown in Table 3.

[Table] Nakatsuta stopped there.

Claims (1)

[Claims] 1 Water-swellable substances () as essential constituents
Contains a hydraulic substance () and a rubber (),
A water-swellable foam sealant characterized by being foamed with a foaming agent.