JPH0417226B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new water-absorbing rubber composition, and more specifically, to a water-absorbing rubber composition that can absorb water and exhibit excellent swelling performance without being affected by metal ions. Water-absorbent rubber compositions made by blending natural rubber or synthetic rubber with super-absorbent resins have been known (Japanese Patent Application Laid-Open No. 108143/1983), and water-stopping materials and caulking materials using these compositions have been known. is widely used in the civil engineering field. However, in conventional water-absorbing rubber compositions, the swelling degree of the water-absorbing substance contained in the composition is low in water containing metal ions, such as hard water, cement curing water, and seawater. However, there are drawbacks such as the swelling performance of the composition is reduced and the composition hardens when soaked for a long period of time. The present inventors have conducted intensive research to overcome these drawbacks and provide a water-absorbing rubber composition that is not affected by metal ions and exhibits excellent swelling performance. The inventors have discovered that a composition consisting of rubber mixed with a water-insoluble superabsorbent resin and a specified amount of a specific ion sequestering agent can be suitable for this purpose, and based on this knowledge, they have completed the present invention. . That is, the present invention provides (A) at least one rubber component selected from natural rubber and synthetic rubber; (B)
It consists of a water-insoluble superabsorbent resin and (C) at least one ion sequestering agent selected from synthetic phosphates and aminocarboxylic acid derivatives, and ( The present invention provides a water-absorbing rubber composition characterized in that the proportion of C) is in the range of 1 to 50% by weight. The natural rubber or synthetic rubber used as component (A) of the present invention may be uncrosslinked rubber, partially crosslinked rubber, or crosslinked rubber. Examples of uncrosslinked rubber include natural rubber, styrene-butadiene rubber, and styrene-butadiene block. Copolymer, styrene-isoprene block copolymer, butadiene rubber, isoprene rubber, acrylonitrile-butadiene rubber, acrylic rubber, ethylene-propylene-dienterpolymer rubber, ethylene-propylene rubber, chloroprene rubber, butyl rubber, halogenated butyl rubber, thiol , polyether rubber, ethylene-vinyl acetate rubber, Hypalon, polyisobutylene, etc. are used. Further, as the partially cross-linked rubber, for example, partially cross-linked butyl rubber or recycled rubber is preferably used. The material used is one that has been subjected to so-called semi-vulcanization or vulcanization treatment by adding and applying heat. These rubbers may be used alone or in a blend of two or more. Also,
Various hardening agents, inorganic and organic reinforcing agents and fillers are used to improve the hardness and texture of rubber, anti-aging agents are used to prevent aging due to sunlight and heat, and various other additives are used to improve processability. Oils, lubricants, and colorants such as dyes and pigments can also be added. Examples of the softening agent include mineral oil, vegetable oil, etc., examples of inorganic reinforcing agents and fillers include clay, magnesium carbonate, hydrated silica, calcium carbonate, carbon black, etc., and organic reinforcing agents and fillers. As the agent, for example, various types of fiber chips and plastic powder can be used. The water-insoluble super absorbent resin used as component (B) in the composition of the present invention includes carboxyl groups, sulfonic acid residues, phosphoric acid residues, quaternary ammonium salt residues,
Natural or synthetic hydrophilic and water containing ionizable groups such as amino groups, imino groups, pyridinium salt residues, nonionic hydrophilic groups such as hydroxyl groups, ether groups, amide groups (chain or cyclic), and nitrile groups. An insoluble polymer substance, such as a copolymer of acrylic acid or its salt and divinylbenzene, acrylonitrile and vinyl chloride or vinylidene chloride, and at least one ethylene type copolymerizable with them. Alkaline hydrolyzate of a polymer obtained by copolymerizing with a monomer,
Formaldehyde crosslinked polymer obtained by hydrolyzing acrylonitrile polymer with alkali,
Formaldehyde crosslinked product of acrylamide copolymer, acid condensate of polyacrylic acid and polyvinyl alcohol, epichlorohydrin crosslinked product of polyvinyl alcohol, phosphoric acid condensate of polyvinyl alcohol, co-formation of 2-hydroxyethyl methacrylate and ethylene glycol methacrylate Polymer, 2-
Copolymer of methyl-5-vinylpyridine and N,N'-methylenebisacrylamide, copolymer of N,N-dimethylaminoethyl methacrylate and N,N'-methylenebisacrylamide, N-vinyl-2 - Copolymers of pyrrolidone and ethylene glycol dimethacrylate, crosslinked products of polyoxyethylene by irradiation, oxidized heat condensates of starch, saponified products of starch-acrylonitrile graft copolymers, graft polymers of starch and acrylic acid Crosslinked product, dried saponified copolymer of vinyl ester and ethylenically unsaturated carboxylic acid or its derivative, crosslinked product of copolymer of α-olefin or vinyl compound and maleic anhydride, oxidation of gelatin Examples include lower heating condensates. Among these, polymers such as acrylic acid and methacrylic acid, and polymers of α-olefin or vinyl compounds and maleic anhydride are preferably used. These polymers or copolymers can be prepared by reacting compounds such as hydroxides, oxides or carbonates of alkali metals or alkaline earth metals such as sodium, potassium, magnesium, barium, ammonia, amines, etc. A roller that improves hydrophilicity is produced. Furthermore, to make it water insoluble,
Polymers containing α,β-unsaturated compounds as monomer components include polyvalent epoxy compounds, polyvalent amines,
It may also be crosslinked with polyhydric alcohol, amino alcohol, polyisocyanate, polyhydric halohydrin, or the like. Among these, a polymer of α-olefin or a vinyl compound and maleic anhydride is particularly preferred because of its excellent durability. These super absorbent resins are used in an amount of 10 to 300 parts by weight, preferably 50 to 200 parts by weight, per 100 parts by weight of the rubber used.
Used in parts by weight. The ion sequestering agent used as component (C) in the water-absorbing rubber composition of the present invention is selected from condensed phosphates and aminocarboxylic acid derivatives. The former condensed phosphate is generally XMO−YP ₂ O ₅
(M in the formula is a monovalent or divalent metal), examples of which include orthophosphates, polyphosphates, metaphosphates, ultraphosphates, etc. The metals constituting the salt are preferably potassium and sodium.
In particular, from the viewpoint of mixing with rubber, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, and potassium tripolyphosphate obtained in powder form are suitable because they are easy to handle and have strong ion-sequestering power. These condensed phosphates may be used alone or in combination of two or more. On the other hand, examples of ion sequestering agents made of aminocarboxylic acid derivatives include iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, and cyclohexane-1,2-acetic acid.
Examples include diaminetetraacetic acid, N-hydroxyethylethylenediaminetriacetic acid, ethylene glycol diethyl ether diaminetetraacetic acid, ethylenediaminetetrapropionic acid, and alkali metal salts and ammonium salts thereof. Among these, nitrilotriacetic acid and ethylenediaminetetraacetic acid are particularly suitable because of their fast ion sequestration rate. Further, these aminocarboxylic acid derivatives may be used alone or in combination of two or more. Furthermore, depending on the type of ions contained in the water, the condensed phosphate and an aminocarboxylic acid derivative may be combined. In the composition of the present invention, the content of the ion sequestering agent as component (C) must be within the range of 1 to 50% by weight based on the total amount of components (A) and (B). .
If this amount is less than 1% by weight, the superabsorbent resin will adsorb ions in water first, resulting in a decrease in swelling, and if it exceeds 50% by weight, the ion sequestering agent will dissolve into water. Even if it is swollen, long-term immersion will reduce the swelling and cause it to become thinner.In addition, the hardness of the rubber composition itself will increase, resulting in a loss of rubber-like elasticity and poor compression resistance. Become. However, when using condensed phosphate as an ion sequestering agent, the amount is 5% relative to the total amount of components (A) and (B).
The amount is preferably within the range of ~50% by weight, and when using an aminocarboxylic acid derivative, the amount is within the range of 2 to 30% by weight based on the total amount of components (A) and (B). It is preferable that there be. The water-absorbent rubber composition of the present invention can be produced by kneading rubber, a superabsorbent resin, and an ion sequestering agent in a conventional manner using a mixer such as a roll mixer, Banbury mixer, or kneader. Alternatively, a composition containing a solvent can be prepared by dissolving or dispersing the rubber in a suitable solvent to obtain a rubber solution or rubber dispersion, and mixing a superabsorbent resin and an ion sequestering agent thereto. This material is suitable for producing paints and putty. The water absorbent rubber composition thus obtained is
In addition to being put into practical use by forming it into a desired shape such as a sheet or string shape suitable for pasting, wrapping, or embedding, it can also be cut into spherical, cylindrical, or square shapes and used as a water stop valve. Depending on the location, it may be filled into the space as a solution, dispersion, or putty.
It is used by applying it to cloth, nets, etc. It can also be combined with rubber or plastic and used as a packing or water stop ring. Furthermore, in addition to the above-mentioned water-stopping materials, it is also suitable for use as desiccants, anti-condensation agents, hand warmers, soil conditioners, and the like. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. The degree of swelling was determined using the following formula. Degree of swelling (times) = weight of swollen sample after immersion/weight of sample before immersion Further, the types of superabsorbent resins used in each example are shown below. KI Gel 201: Manufactured by Clarei Soprene Chemical Co., Ltd., a super absorbent resin cross-linked with isobutylene-maleic anhydride copolymer Aqua Keep 4S: Manufactured by Steel Chemical Co., Ltd., acrylic super absorbent resin Sunwet IM-300: Manufactured by Sanyo Chemical Co., Ltd. Starch-acrylic superabsorbent resin Example 1 100 parts by weight of chloroprene rubber [Skyprene rubber, manufactured by Toyo Soda Co., Ltd.] and the superabsorbent resin shown in Table 1
After mixing 80 parts by weight and 5 to 80 parts by weight of sodium tripolyphosphate as an ion sequestering agent using a roll at 50°C, the mixture was molded for 15 minutes using a heated press at 100°C. The obtained water-absorbing rubber composition sample measuring 50 x 50 mm and 3 mm in thickness was immersed in a 2.5% by weight calcium hydroxide slurry to examine changes in swelling degree over time. The results are shown in Table 1. Comparative Example 1 A rubber composition sample of the same size was obtained in the same manner as in Example 1 except that the sodium tripolyphosphate in Example 1 was not used. This product was immersed in a 2.5% by weight calcium hydroxide slurry solution, and the change in degree of swelling over time was examined. The results are shown in Table 1.

[Table] Example 2 100 parts by weight of chloroprene rubber, 10 parts by weight of hydrated silica, 5 parts by weight of zinc white, 4 parts by weight of magnesium oxide, 0.5 parts by weight of ethylene thiourea as a vulcanization accelerator, 1 part by weight of stearic acid, naphthene 5 parts by weight of oil (manufactured by Sun Oil Co., Ltd., Sansen 450), 1 part of antioxidant (manufactured by Ouchi Shinko Co., Ltd., Nokuratsuku NS-6)
After mixing 80 parts by weight of a super absorbent resin as shown in Table 2 and 5 to 40 parts by weight of sodium tripolyphosphate as an ion sequestering material using a roll at 50°C, the mixture was heated using a heated press at 160°C for 30 minutes. Crosslinking molding was performed. The resulting rubber composition sample measuring 50 x 50 mm and 3 mm in thickness was immersed in a 2.5% by weight calcium hydroxide slurry to examine changes in swelling degree over time. The results are shown in Table 2. Comparative Example 2 A rubber composition sample of the same size was obtained in the same manner as in Example 2, except that the sodium tripolyphosphate in Example 2 was not used. This product was immersed in a 2.5% by weight calcium hydroxide slurry solution, and the change in degree of swelling over time was examined. The results are shown in Table 2.

【table】

[Table] Example 3 100 parts by weight of polyisoprene rubber (manufactured by Kuraray Isoprene Chemical Co., Ltd., Kuraprene IR-10), 3 parts by weight of stearic acid, 1 weight of antioxidant (manufactured by Ouchi Shinko Co., Ltd., Nokuratsuku NS-6) parts, 5 parts by weight of zinc white,
3 parts by weight of tetramethylthiuram disulfide, 3rd
100 parts by weight of a superabsorbent resin as shown in the table and 2 to 2 to ethylenediaminetetraacetic acid as an ion sequestering agent.
After mixing 20 parts by weight with a roll at 40℃, it was heated to 170℃.
Cross-linking molding was performed for 5 minutes using a hot press.
The obtained rubber composition sample of 50 x 50 mm and 3 mm thickness was
It was immersed in an aqueous solution containing 0.3% by weight of calcium chloride and 0.5% by weight of magnesium chloride, and the change in degree of swelling over time was examined. The results are shown in Table 3. Comparative Example 3 A rubber composition sample of the same size was obtained in the same manner as in Example 3, except that ethylenediaminetetraacetic acid in Example 3 was not used. This product was immersed in an aqueous solution containing 0.3% by weight of calcium chloride and 0.5% by weight of magnesium chloride, and the change in degree of swelling over time was examined. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1. (A) at least one rubber component selected from natural rubber and synthetic rubber, (B) super absorbent resin insoluble in water, and (C) selected from synthetic phosphates and aminocarboxylic acid derivatives. 1. A water-absorbing rubber composition comprising at least one ion sequestering agent, wherein the proportion of (C) to the total amount of (A) and (B) is in the range of 1 to 50% by weight.