JP2007169372A - Water-swellable sealing material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-swellable sealing material exhibiting high swellability and stable swellability for a long term to water containing much polyvalent metal ion, such as cement water and calcium chloride water and little eluating fraction to aqueous liquids. <P>SOLUTION: The water-swellable sealing material comprises rubber (A) and a water-swellable material (B) comprising a polymer crosslinked copolymer particle obtained by copolymerizing a mixture of monomers, comprising (i) 20-60 mol.% mixture of sulfonic group-containing acrylamide monomers, containing unneutralized-sulfonic group-containing acrylamide monomer (a) and neutralized-sulfonic group-containing acrylamide monomer (b) at a molar ratio (a)/(b) of from 20/80 to 60/40, (ii) 35-79 mol.% acrylamide monomer and (iii) ≤5 mol.% unneutralized (meth)acrylic acid monomer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water-swellable sealing material. In more detail, civil engineering works that show high swellability to water containing a high concentration of polyvalent metal ions such as cement water and calcium chloride water, stable swelling over a long period of time, and little elution into aqueous liquids The present invention relates to a water-swellable sealing material useful as a waterproofing material in construction work.

  Many techniques have been proposed in which a water-swellable sealing material is prepared by containing a water-absorbing resin in a thermoplastic resin or rubber, and this is used as a water-stopping material for civil engineering or construction work. However, due to the problem of salt water resistance, there is a drawback that the swelling rate is lowered when a long-term contact with an aqueous solution containing a polyvalent metal ion such as hard water or seawater and a sufficient water-stopping effect cannot be exhibited.

  In order to solve such a problem, a water-absorbing material composed of sulfoalkyl (meth) acrylate, 2-acrylamido-2-methylpropanesulfonic acid or the like has been proposed (see, for example, Patent Documents 1 and 2), which is used as rubber or the like. A salt-resistant swelling agent (water-swellable sealing material) used has been proposed (see, for example, Patent Documents 3, 4, and 5). Moreover, in order to improve the elution at the time of being immersed in water for a long time, mixing a urethane prepolymer and these swelling agents is proposed (patent documents 6 and 7).

  In recent years, when water-swellable sealing materials are used as concrete segment materials in urban submarine tunnels and subway construction, there is an increasing demand for higher swelling and stability over time for water containing polyvalent metal ions, especially cement water. ing.

  In spite of such a requirement, in the case of a salt-resistant swelling agent using a water-absorbing material composed of the aforementioned sulfoalkyl (meth) acrylate, 2-acrylamido-2-methylpropanesulfonic acid, etc., the swelling property against cement water And the stability over time was not sufficient. For this reason, when the said water absorbing material was used as a concrete segment material in the subway construction which requires the high swelling property with respect to cement water, the case where sufficient performance was not obtained was seen.

JP-A-61-36309 Japanese Patent Laid-Open No. 62-144748 JP-A-61-31450 Japanese Patent Laid-Open No. 3-157455 JP-A-6-1886 Japanese Patent Laid-Open No. 2-155953 Japanese Patent Laid-Open No. 2-155554

  The object of the present invention is to exhibit high swellability with respect to water containing a high concentration of polyvalent metal ions such as cement water and calcium chloride water, and stable swellability over a long period of time. The object is to provide a swellable sealing material.

  As a result of intensive studies to solve the above problems, the present inventors have found that a mixture of specific monomers has a high water absorption particularly in cement water among aqueous solutions containing polyvalent metal ions in a specific ratio. A water-swellable sealing material prepared by adding a water-swellable substance prepared by adding a mixture of such specific monomers at a specific ratio to rubber and having excellent gel shape retention and gel strength is cement water, calcium chloride water. The present invention is completed by finding high swellability with respect to water containing a high concentration of equivalent metal ions, showing stable swellability over a long period of time, and less elution into an aqueous liquid. It came.

That is, the present invention relates to rubber (A),
(I) The sulfonic acid group-containing acrylamide monomer (a) in which the sulfonic acid group is not neutralized and the sulfonic acid group-containing acrylamide monomer (b) in which the sulfonic acid group is neutralized are ) / 20-60 mol% of a mixture of sulfonic acid group-containing acrylamide monomers comprising (B) in a molar ratio of 20 / 80-60 / 40,
(Ii) acrylamide monomer 35-79 mol%,
(iii) a mixture of said monomers containing 5 mol% or less of unneutralized (meth) acrylic acid monomer,
A water-swellable sealing material comprising a water-swellable substance (B) comprising polymer crosslinked copolymer particles obtained by copolymerization is provided.

  The water-swellable sealing material of the present invention exhibits high swellability with respect to water containing a high concentration of polyvalent metal ions such as cement water and calcium chloride water, and exhibits stable swellability over a long period of time. Since there are few minutes, it can be used as a waterproofing material in civil engineering and construction work.

Next, details necessary for carrying out the present invention will be described in detail.
Examples of the rubber (A) used in the water-swellable sealing material of the present invention include synthetic rubber such as polybutadiene rubber, polyisoprene rubber, styrene-butadiene rubber, chloroprene rubber, isoprene-isobutylene rubber, ethylene-propylene copolymer rubber, and chlorine. Synthetic rubber or synthetic rubber having rubber elasticity such as sulfonated polyethylene, chlorosulfonated polyethylene, ethylene-vinyl acetate copolymer, soft polyvinyl chloride, polyurethane, etc. are mentioned, and synthetic rubber or a mixture thereof with natural rubber is particularly preferable. . These may be used alone or in combination of two or more. As the synthetic rubber, chloroprene rubber and styrene-butadiene rubber are preferable.

The water-swellable substance (B) used in the water-swellable sealing material of the present invention is obtained from polymer cross-linked copolymer particles obtained by copolymerizing a mixture of monomers in a specific ratio in the presence of a cross-linking agent. It will be.
The composition of such a monomer includes (i) a sulfonic acid group-containing acrylamide monomer (a) in which the sulfonic acid group is not neutralized and a sulfonic acid group-containing acrylamide monomer in which the sulfonic acid group is neutralized ( 20) to 60 mol% of a sulfonic acid group-containing acrylamide monomer comprising (a) / (b) in a molar ratio of 20/80 to 60/40, (ii) an acrylamide system It consists of a monomer of 35 to 79 mol%, and (iii) an unneutralized (meth) acrylic acid monomer of 5 mol% or less.

  Examples of the sulfonic acid group-containing acrylamide monomer (a) in which the sulfonic acid group is not neutralized include, for example, the general formula (1)

（式中、Ｒ^１は、水素原子又はメチル基、Ｘは-ＮＨ-、Ｒ^２は直鎖状または分岐鎖状の炭素原子数が２〜４のアルキレン基を示す。）で表される化合物が挙げられ、この一般式（１）で表される化合物であることが好ましい。

(Wherein R ¹ represents a hydrogen atom or a methyl group, X represents —NH—, and R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms). It is preferable that it is a compound represented by this general formula (1).

  Specific examples of the sulfonic acid group-containing acrylamide monomer (a) represented by the general formula (1) include 2-acrylamide-2-methylpropanesulfonic acid and 2-methacrylamide-2-methylpropanesulfone. An acid etc. can be mentioned. Of these, 2-acrylamido-2-methylpropanesulfonic acid is particularly preferable.

  Examples of the sulfonic acid group-containing acrylamide monomer (b) in which the sulfonic acid group is neutralized include, for example, the general formula (2)

(In the formula, R ¹ is a hydrogen atom or a methyl group, X is —NH—, R ² is a linear or branched alkylene group having 2 to 4 carbon atoms, Y is an alkali metal or alkaline earth metal) Or an ammonium group.), And a compound represented by the general formula (2) is preferable.

  Specific examples of the sulfonic acid group-containing acrylamide monomer (b) represented by the general formula (2) include 2-acrylamido-2-methylpropanesulfonic acid and 2-methacrylamide-2-methylpropanesulfone. Examples include alkali metal salts such as acids, alkaline earth metal salts, and ammonium salts. Examples of the alkali metal salt include sodium salt, potassium salt, lithium salt, and rubidium salt. Examples of the alkaline earth metal salt include calcium salt and magnesium salt. Of these, alkali metal salts such as sodium salt, potassium salt, lithium salt and rubidium salt of 2-acrylamido-2-methylpropanesulfonic acid are particularly preferable.

The polymer cross-linked copolymer particles used in the present invention include (i) a sulfonic acid group-containing acrylamide monomer (a) whose sulfonic acid group is not neutralized and a sulfonic acid group-containing neutralized sulfonic acid group. By copolymerizing the acrylamide monomer (b) at a molar ratio of (a) / (b) of 20/80 to 60/40, the water absorption with respect to 1% cement water is controlled to 55 g / g or more. be able to.
When the molar ratio of the neutralized sulfonic acid group-containing acrylamide monomer (b) is less than 40, the water absorption rate of 1% cement water becomes low and the requirement is not satisfied. Moreover, when the molar ratio of the neutralized sulfonic acid group-containing acrylamide monomer (b) exceeds 80, not only the water absorption rate of cement water is improved, but also the strength of the water absorbing gel is lowered.

  The sulfonic acid group-containing acrylamide monomer (a) and the sulfonic acid group-containing acrylamide monomer (b) may be different types or the same type. When using one type of sulfonic acid group-containing acrylamide monomer that is different from the above (a) and (b) except for neutralization, the neutralization rate of the sulfonic acid group should be adjusted to 40 to 80%. Is preferable because it can be prepared at a molar ratio of (a) / (b) = 20/80 to 60/40.

  The mixture (i) of the sulfonic acid group-containing acrylamide monomer comprising the sulfonic acid group-containing acrylamide monomer (a) and (b) in the molar ratio is 20 to 60 mol in the raw material monomer mixture. % Content. By containing 20 to 60 mol%, the water absorption with respect to 1% cement water can be controlled to 55 g / g or more. Among these, it is preferable to contain 20-50 mol%.

  When the content of the mixture (i) of the sulfonic acid group-containing acrylamide monomer is less than 20 mol%, the water absorption of the cement water becomes low and the requirement is not satisfied. Further, when the content of the monomer mixture (i) exceeds 60 mol%, the molecular weight of the copolymer is lowered due to polymerizability, and when the water is absorbed by the copolymer particles, It becomes a factor that leads to a decrease in gel strength, and when added to other materials, it leads to elution of components, which is not preferable. Further, the fluidity of the resulting copolymer particles is impaired, and the particles are difficult to handle, such as the particles tend to aggregate.

  The acrylamide monomer (ii) is contained in the raw material monomer mixture in an amount of 35 to 79 mol%, preferably 49 to 79 mol%. Specific examples thereof include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methyl (meth) acrylamide, N-isopropyl (meth) acrylamide and the like. Of these, (meth) acrylamide is preferred.

  Examples of the non-neutralized (meth) acrylic acid monomer (iii) include acrylic acid and methacrylic acid. The (meth) acrylic acid monomer is contained in an amount of 5 mol% or less, preferably 1 mol% or less in the mixture of raw material monomers. By containing the (meth) acrylic acid monomer in an amount of 5 mol% or less, the water absorption rate of the cement water can be increased while keeping the water absorption gel strength high. When the (meth) acrylic acid monomer exceeds 5 mol%, the water absorption of the cement water becomes low, and when the water is absorbed for a long time, the water absorption of the cement water changes unstably and changes. . Further, when the amount of the sulfonic acid group-containing acrylamide monomer (i) is increased in order to prevent this, it becomes a water paste when the copolymer particles absorb water, causing a decrease in gel strength and others. When added to the above materials, there is a problem that leads to elution of components, which is not preferable.

  The polymer cross-linked copolymer particles used in the present invention include (i) a mixture of the sulfonic acid group-containing acrylamide monomer (a) and (b) in an amount of 20 to 50 mol%, and (ii) an acrylamide monomer. By copolymerizing a monomer mixture containing 49 to 79 mol%, (iii) 1 mol% or less of an unneutralized acrylic acid monomer, all water absorption, gel strength, gel shape retention, etc. The performance can be further improved.

  The polymer crosslinked copolymer particles preferably have an average particle size of 1 to 50 μm, more preferably 10 to 30 μm. If it is less than 1 μm, the polymer cross-linked copolymer particles tend to remain untreated and difficult to handle, and if it exceeds 50 μm, the appearance of the water-swellable sealing material added to the rubber is impaired, and water swelling This causes a decrease in the physical and mechanical strength of the sealing material.

  Polymers obtained by polymerizing a mixture of the monomers may self-crosslink without using a crosslinking agent, but crosslinking using a crosslinking agent may result in copolymer particles having excellent water absorption. It is preferable in manufacturing.

Examples of the crosslinking agent include a monomer having two or more ethylenically unsaturated bonds and a compound having two or more functional groups that react with the functional group of the monomer in the monomer mixture.
Preferred examples of the monomer having two or more ethylenically unsaturated bonds include di (meth) acrylic acid ester, tri (meth) acrylic acid ester, and bisacrylamide. Examples of di (meth) acrylic acid esters include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, di (meth) acrylic acid carb Examples include mill esters.

Examples of the tri (meth) acrylic acid ester include trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate.
Examples of bisacrylamide include N, N′-methylenebisacrylamide and N, N′-ethylenebisacrylamide. Among these, it is preferable to use ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, and N, N′-methylenebis (meth) acrylamide.

  Moreover, as a compound which has two or more functional groups which react with the functional group which the monomer in the said mixture of monomers has, it has two or more functional groups which react with the carboxyl group which (meth) acrylic acid has Compounds. Specifically, for example, a compound having two or more epoxy groups, a compound having two or more isocyanate groups, and the like are used, and it is particularly preferable to use a diglycidyl ether compound.

  Examples of the compound having two or more epoxy groups include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, and polyglycerin diglycidyl ether. Of these, ethylene glycol diglycidyl ether is preferably used.

  Examples of the compound having two or more isocyanate groups include 2,4-tolylene diisocyanate and hexamethylene diisocyanate.

  The monomer having two or more ethylenically unsaturated bonds and the compound having two or more functional groups that react with the carboxyl group of the (meth) acrylic acid are based on 100 mol% of the monomer mixture. Preferably it is used within the range of 0.001 to 1 mol%, more preferably 0.01 to 0.1 mol%. If it is the range of 0.001-1 mol%, while sufficient water absorption performance will be obtained, sufficient crosslinked structure can be obtained.

  The polymer cross-linked copolymer particles used in the water-swellable sealing material of the present invention can be produced by a conventionally known polymerization method, for example, a method of polymerizing while stirring in a twin-type kneader, a container Among them, there are a method of cast polymerization, a method of continuous stationary polymerization on a driving belt, a reverse phase suspension polymerization method, and the like. Specifically, a mixture of sulfonic acid group-containing acrylamide monomers comprising (a) and (b) in the molar ratio (i) 20 to 60 mol%, (ii) acrylamide monomer 35 Radical polymerization is initiated in the presence of a crosslinking agent and a surfactant in a mixture of non-neutralized (meth) acrylic acid monomers consisting of ˜79 mol% and (iii) 5 mol% or less Polymerization is performed using an agent. Among these, the reverse-phase suspension polymerization method can perform polymerization by dispersing a water-soluble ethylenically unsaturated monomer in a hydrophobic organic solvent by using a surfactant. This is preferred in that crosslinked polymer particles having a particle size can be obtained.

The following method is mentioned as a more specific method of the reverse phase suspension polymerization method.
A sulfonic acid group-containing acrylamide monomer (a) in which the sulfonic acid group is not neutralized and a sulfonic acid group-containing acrylamide monomer (b) in which the sulfonic acid group is neutralized are dissolved as necessary. These are dissolved by weighing them into the water. Alternatively, the sulfonic acid group-containing acrylamide monomer (a) that has not been neutralized is weighed and added to an aqueous solution containing a polymerization inhibitor and dissolved in a neutralizer, if necessary, to neutralize and dissolve it. Acrylamide monomer (ii) and (meth) acrylic acid monomer (iii) are added and dissolved therein. Subsequently, a crosslinking agent, a radical polymerization initiator, and if necessary, a water-soluble chain transfer agent such as thiols, thiolic acids, secondary alcohols, amines, hypophosphites, etc. are added, if necessary A monomer aqueous solution is prepared by introducing an inert gas such as nitrogen and degassing.
On the other hand, a surfactant is placed in a hydrophobic organic solvent in the polymerization apparatus, and if necessary, heated and dissolved slightly, and an inert gas such as nitrogen is introduced to perform deaeration. The monomer aqueous solution is added to the hydrophobic organic solvent, and heating is started with stirring. During this period, the aqueous monomer solution in the reaction system becomes fine droplets and is suspended while being dispersed in the hydrophobic organic solvent. Over time, heat generation occurs and the polymerization starts.

  After the start of polymerization, depending on the state of heat generation, cooling or heating is appropriately performed. The polymerization reaction temperature is preferably in the range of 60 to 100 ° C, more preferably 60 to 80 ° C.

  The water-swellable substance used in the present invention is added with a sucrose fatty acid ester for the purpose of preventing fusion between primary particles of the polymer crosslinked copolymer particles and enhancing mechanical stability and thermal stability. May be. As the sucrose fatty acid ester, the same ones as described above can be used. Among these, a sucrose stearate having a monoester as a main component and an HLB of 1 to 11 is preferred depending on the composition of diester and triester.

  The water-swellable substance used in the present invention has a particularly high water absorbency with respect to cement water among aqueous solutions containing polyvalent metal ions such as calcium salts and magnesium salts, and preferably has a water absorbency with respect to 1% cement water of 55 g / g or more. Is 60 g / g or more. At the same time, it has high gel form retention and gel strength.

  As the water swellable substance, a water swellable substance other than the above can be used in combination with the above water swellable substance. Examples of water-swellable substances other than the above include hydrophilic urethane prepolymers, polymerized hydrophilic urethane prepolymers, carboxymethylcellulose, polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, and the like. Polymers or polymerized hydrophilic urethane prepolymers are preferred.

  The hydrophilic urethane prepolymer has the general formula (3)

（式中（ＯＲ^４）はオキシエチレン基と炭素原子数３〜４のアルキレン基を有するオキシアルキレン基からなるポリオキシアルキル鎖、ｎは２から２０００の整数、ｍは１〜８の整数）で表される多価アルコールとポリイソシアネートとを反応させて得られる末端イソシアネート基含有の低分子量ポリウレタン化合物を意味する。

(Wherein (OR ⁴ ) is a polyoxyalkyl chain comprising an oxyethylene group and an oxyalkylene group having an alkylene group having 3 to 4 carbon atoms, n is an integer of 2 to 2000, and m is an integer of 1 to 8) It means a low molecular weight polyurethane compound containing a terminal isocyanate group obtained by reacting the polyhydric alcohol represented with polyisocyanate.

  Examples of the polyhydric alcohol represented by the general formula (3) include diols such as polyoxypropylene glycol, poly (oxypropylene) poly (oxyethylene) glycol, poly (oxytetramethylene) glycol, and poly (oxypropylene). Examples include triols such as triol, poly (oxypropylene) poly (oxyethylene) triol, poly (oxypropylene) poly (oxyethylene) poly (oxypropylene) triol, sorbitol, pentaerythritol, and sucrose.

  Examples of the isocyanate compound include 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, dianisidine diisocyanate, tolden diisocyanate, hexamethylene diisocyanate, metaxylylene diisocyanate, 1,4-butane diisocyanate, 1,6- Examples thereof include hexane diisocyanate, 3,3′-dimethyldiphenylmethane diisocyanate, 1,5-naphthylene diisocyanate and isomers or hydrogenated products thereof.

  By previously mixing the polymer crosslinked copolymer particles obtained by copolymerizing the monomer mixture in the presence of a crosslinking agent and the hydrophilic polyurethane prepolymer, the hydrophilic polyurethane prepolymer is mixed. Since the terminal isocyanate group reacts with the carboxylic acid group and sulfonic acid group in the polymer crosslinked copolymer particles to form a paste, it can be easily mixed with rubber.

  In addition, the hydrophilic polyurethane prepolymer is mixed with the polymer crosslinked copolymer particles, or in advance, a heavy metal compound such as tin octylate or dibutyltin dilaurate, or 3,3′-dichro-4,4′-diaminodiphenylmethane. It may be polymerized in advance using a curing catalyst such as amines such as (MOCA) or a curing accelerator such as polyester polyol, polyether polyol, alcohols or amino alcohol which are usually used.

The water-swellable sealing material of the present invention can be obtained by mixing the rubber (A) and the water-swellable substance (B) at a weight ratio of 95: 5 to 50:50. If the ratio of the water-swellable substance is less than 5% by weight, the water-swelling / swelling property of the resulting water-swellable sealing material will decrease, and if it exceeds 50% by weight, the strength of the resulting water-swellable rubber will decrease, The amount of elution increases.
(A) (B) Both are preferably mixed and dispersed by uniformly dispersing the water-swellable substance in rubber by a mechanical method. Although there is no restriction | limiting in particular about the dispersion method, For example, it is preferable to use the mixing apparatus used normally, such as a kneading roll, an oven roll, a kneader, and a Banbury mixer.

In the water-swellable sealing material of the present invention, in addition to the essential components of the rubber (A) and the water-swellable substance (B), a vulcanizing agent and a vulcanization accelerator are added as necessary, as long as the purpose is not lost. Agents, vulcanization aids, inorganic fillers, reinforcing agents, softeners, plasticizers, colorants, ultraviolet absorbers, and the like can be added.
These additives may be mixed simultaneously with the essential components, or may be mixed sequentially. Further, the water-swellable sealing material of the present invention may be used after performing molding such as extrusion molding, press molding or vulcanization molding, if necessary. At that time, the water-swellable sealing material of the present invention may be molded into a predetermined shape.

  The water-swellable sealing material of the present invention is suitably used as, for example, a seal segment joint surface in civil engineering work such as tunnel excavation and a water-stopping material in building work.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these. In the following, all parts and percentages are based on weight unless otherwise specified.

  1% cement water and 1% calcium chloride water were prepared by the following method. Various properties of the resin of the present invention were measured by the following methods.

[Preparation of 1% cement water]
As for 1% cement water, 30 g of Portland cement was weighed in a 5 L plastic flask, and ion-exchanged water maintained at 25 ° C. so that the total weight was 3 kg was poured, stirred for 5 minutes, and then kept at 25 ° C. for 24 hours. I left it alone. Thereafter, the supernatant was prepared by filtering.

[Preparation of 1% calcium chloride water]
39.7 g of CaCl ₂ · 2H ₂ O was weighed into a 5 L plastic flask, and ion-exchanged water was poured so that the total weight was 3 kg, and the CaCl ₂ · 2H ₂ O was dissolved.

<Measurement method>
[Measurement of water absorption]
0.1 g of polymer particles obtained in Reference Examples described later were weighed. Each solution of 1% cement water and 1% calcium chloride water was weighed into a 100 g beaker, 0.1 g of dry resin powder was added, and water was absorbed for 1 hour. A Buchner funnel was attached to the suction bottle, and qualitative filter paper (Whatman No. 5) with an opening of 2.5 μm was attached. The mixture of the resin and the water after water absorption for 1 hour was poured into a Buchner funnel while keeping the suction bottle at a reduced pressure with an aspirator. Filtration was performed until the liquid content was removed. The liquid absorption ratio W (g / g) is the mass a (g) of the sample, the mass b _60min (g) of (gel resin + qualitative filter paper + Buchner funnel) after draining, (qualitative filter paper + Buchner funnel) before filtration It calculated from the value of mass c (g) of according to the following formula.

[Measurement of average particle size and particle size distribution]
Using the polymer particles obtained in Reference Examples described later as samples, the average particle size and particle size distribution were measured using a laser diffraction / scattering particle size distribution measuring device LA-910 (manufactured by Horiba, Ltd.). The median diameter measured on a volume basis was defined as the average particle diameter.
[Measurement of swelling rate]
The water-swellable sealing material obtained in Examples described later was measured for the swelling rate after being immersed in 1% cement water and 1% calcium chloride water for 30 days. The swelling rate (%) was calculated according to the following formula from the mass a (g) of the sample before swelling and the sample mass b (g) after swelling for 30 days.

<< Reference Example 1 >>
750 g of cyclohexane, Rhedol SP-S10V (sorbitan monostearate, HLB = 5, Kao Corporation) in a polymerization tank of a 130 mm inner diameter 2 L separable flask equipped with a three-stage pitched paddle blade with a stirring blade diameter of 95 mm, a condenser, and a thermometer Product) After charging 10.0 g, a reflux cooling dehydration tube and a dropping funnel were provided, and stirring was started at a stirring speed of 700 rpm. Meanwhile, TBAS-Q (2-acrylamido-2-methylpropanesulfonic acid, manufactured by MRC Unitech Co., Ltd.) 207 g (32.5 mol%) was added to a 2 L disc, and hydroxy-tetramethyl-1 was cooled from the outside. -Non-neutralized 2-acrylamide-2 by dropping 410 g of an aqueous sodium hydroxide solution containing 0.02 g of piperidine oxyl and dissolving 24.0 g of sodium hydroxide to neutralize 60 mol% of TBAS-Q An aqueous solution containing 40% by mole of methylpropanesulfonic acid and 60% by mole of 2-acrylamido-2-methylpropanesulfonic acid that had been neutralized was prepared. After 142 g (67.3 mol%) of acrylamide, 0.5 g (0.2 mol%) of acrylic acid, 0.15 g of N, N′-methylenebisacrylamide and 0.5 g of ammonium persulfate were added to this solution and dissolved. Nitrogen gas was blown to expel dissolved oxygen.

  Next, the monomer aqueous solution containing the polymerization initiator and the crosslinking agent obtained as described above was added to the above-mentioned cyclohexane, 0.3 g of sodium hydrogen sulfite was added in a powder state, and then the temperature was increased to 70 ° C. Polymerization was started by raising the temperature. After the exotherm due to polymerization had subsided, 3.0 g of DK ester F-90 (sucrose stearate ester, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added. While stirring at a stirring speed of 700 rpm for 1 hour, the temperature in the system was controlled to a temperature of 60 ° C to 70 ° C. After 330 g of water was extracted by azeotropic dehydration, the resin was taken out and dried at 70 ° C. under reduced pressure to obtain polymer particles A. The volume-based median diameter of the polymer particles A was 20 μm, and the fluidity was smooth.

  The liquid absorption characteristics and the state of the water absorbing gel are summarized in Table 2. The polymer particles A were excellent in gel shape retention, and high gel strength and water absorption performance were obtained.

<< Reference Example 2 >>
By adding 410 g of an aqueous sodium hydroxide solution in which 30.0 g of sodium hydroxide was added dropwise to neutralize 75 mol% of TBAS-Q, the unneutralized 2-acrylamido-2-methylpropanesulfonic acid was in a molar ratio. Preparation of polymer particles B was carried out in the same manner as in Example 1 except that an aqueous solution containing 25% of a neutralized 2-acrylamido-2-methylpropanesulfonic acid in a molar ratio of 75% was prepared. It was. Particles were obtained in a state where the primary particles did not aggregate. The volume-based median diameter of the polymer particles B was 16 μm, and the fluidity was smooth. The liquid absorption characteristics and the state of the water absorbing gel are summarized in Table 2. The polymer particles B were excellent in gel shape retention, and high gel strength and liquid absorption performance were obtained.

<< Reference Example 3 >>
TBAS-Q (280 g, 56.7 mol%) was added, and 410 g of an aqueous sodium hydroxide solution containing 0.03 g of hydroxy-tetramethyl-1-piperidineoxyl and 29.8 g of sodium hydroxide was added dropwise while cooling from the outside. By neutralizing 55 mol% of TBAS-Q, 2-acrylamido-2-methylpropane sulfone neutralized with a non-neutralized 2-acrylamido-2-methylpropanesulfonic acid at a molar ratio of 45% An aqueous solution containing 55% acid by mole was prepared. 66.1 g (39.1 mol%) of acrylamide, 7.2 g (4.2 mol%) of acrylic acid, 0.15 g of N, N′-methylenebisacrylamide and 0.5 g of ammonium persulfate are added to this solution and dissolved. Thereafter, polymer particles C were prepared by the same operation as in Example 1 except that a monomer aqueous solution containing a polymerization initiator and a crosslinking agent prepared by blowing nitrogen gas and expelling dissolved oxygen was used. It was. Particles were obtained in a state where the primary particles did not aggregate. The volume-based median diameter of the polymer particles C was 17 μm. The liquid absorption characteristics and the state of the water absorbing gel are summarized in Table 2. Although the polymer particles C were somewhat heavy and the water-absorbing gel was somewhat fluid, high gel strength and liquid absorption performance were obtained.

<< Reference Example 4 >>
By dropping 410 g of an aqueous sodium hydroxide solution in which 16.0 g of sodium hydroxide was dissolved to neutralize TBAS-Q by 40 mol%, 2-acrylamido-2-methylpropanesulfonic acid that was not neutralized was in a molar ratio. Preparation of polymer particles D was carried out in the same manner as in Example 1, except that an aqueous solution containing 60% by moles of neutralized 2-acrylamido-2-methylpropanesulfonic acid was contained in a molar ratio of 40%. It was. Particles were obtained in a state where the primary particles did not aggregate. The volume-based median diameter of the polymer particles D was 18 μm, and the fluidity was smooth. The liquid absorption characteristics and the state of the water absorbing gel are summarized in Table 2. The polymer particles D were excellent in gel shape retention, and high gel strength and liquid absorption performance were obtained.

<< Reference Example 5 >>
A polymerization tank of a 2-liter separable flask having an inner diameter of 130 mm, equipped with a three-stage pitched paddle blade with a stirring blade diameter of 95 mm, a cooling tube, and a thermometer was charged with 750 g of cyclohexane and 10.0 g of Rheodor SP-S10V, and then a reflux cooling dehydration tube A dropping funnel was provided, and stirring was started at a stirring speed of 700 rpm. On the other hand, TBAS-Q 194 g (28.2 mol%) was added to a 2 L disc, 0.02 g of hydroxy-tetramethyl-1-piperidineoxyl was dissolved while cooling from the outside, and 24.0 g of sodium hydroxide was dissolved. By adding dropwise 410 g of an aqueous sodium oxide solution to neutralize 60 mol% of TBAS-Q, the neutralized 2-acrylamido-2-methylpropanesulfonic acid is neutralized at a molar ratio of 2- An aqueous solution containing 60% of acrylamide-2-methylpropanesulfonic acid by molar ratio was prepared. After 146 g (62.0 mol%) of acrylamide, 23.4 g (9.8 mol%) of acrylic acid, 0.15 g of N, N′-methylenebisacrylamide and 0.5 g of ammonium persulfate were added to this solution and dissolved. Nitrogen gas was blown to expel dissolved oxygen.

  Next, the monomer aqueous solution containing the polymerization initiator and the crosslinking agent obtained as described above was added to the above-mentioned cyclohexane, 0.3 g of sodium hydrogen sulfite was added in a powder state, and then the temperature was increased to 70 ° C. Polymerization was started by raising the temperature. After the exotherm due to polymerization had subsided, the temperature in the system was controlled at a temperature of 60 ° C. to 70 ° C. while stirring at 700 rpm for 1 hour. After 330 g of water was extracted by azeotropic dehydration, the resin was taken out and dried at 70 ° C. under reduced pressure to obtain polymer particles E. The liquid absorption characteristics of this polymer particle E and the state of the water absorbing gel are summarized in Table 2. The fluidity of the polymer particles E was slightly heavy, and a slight fluidity was observed in the water-absorbing gel. Further, the gel strength was slightly weak and the water absorption rate of cement water was particularly low in the liquid absorption characteristics.

<< Reference Example 6 >>
By dropping 410 g of an aqueous sodium hydroxide solution in which 12.0 g of sodium hydroxide was dissolved to neutralize TBAS-Q by 30 mol%, unneutralized 2-acrylamido-2-methylpropanesulfonic acid was in a molar ratio. Preparation of polymer particles F was carried out in the same manner as in Reference Example 5 except that an aqueous solution containing 70% of neutralized 2-acrylamido-2-methylpropanesulfonic acid in a molar ratio of 30% was prepared. It was. The liquid absorption characteristics of the polymer particles F and the state of the water absorption gel are summarized in Table 2. The fluidity of the polymer particles F was slightly heavy, and a slight fluidity was observed in the water-absorbing gel. Further, the gel strength was slightly weak and the water absorption ratio was relatively low.

<< Reference Example 7 >>
By adding 410 g of an aqueous sodium hydroxide solution in which 40.0 g of sodium hydroxide was added dropwise to neutralize TBAS-Q to 100 mol%, unneutralized 2-acrylamido-2-methylpropanesulfonic acid was in a molar ratio. The polymer particles G were prepared in the same manner as in Reference Example 5 except that an aqueous solution containing 0% and neutralized 2-acrylamido-2-methylpropanesulfonic acid in a molar ratio of 100% was prepared. It was. The liquid absorption characteristics of the polymer particles G and the state of the water absorbing gel are summarized in Table 2. The fluidity of the polymer particles G was slightly heavy, and the water-absorbent gel was slightly water-glue and had high fluidity and low gel strength. The water absorption ratio was also relatively low.

<< Reference Example 8 >>
TBAS-Q (137 g, 17.7 mol%) was added, and 410 g of aqueous sodium hydroxide solution containing 0.02 g of hydroxy-tetramethyl-1-piperidineoxyl and 15.9 g of sodium hydroxide was added dropwise while cooling from the outside. By neutralizing 60 mol% of TBAS-Q, 2-acrylamido-2-methylpropane sulfone neutralized with 2-acrylamido-2-methylpropanesulfonic acid that is not neutralized by 40% in molar ratio An aqueous solution containing 60% acid by mole was prepared. Prepared by adding 219 g (82.3 mol%) of acrylamide, 0.15 g of N, N′-methylenebisacrylamide and 0.5 g of ammonium persulfate to this solution and then blowing out nitrogen to blow out dissolved oxygen. Polymer particles H were prepared in the same manner as in Reference Example 5 except that the monomer aqueous solution containing the polymerization initiator and the crosslinking agent was used. The liquid absorption characteristics of the polymer particles H and the state of the water absorbing gel are summarized in Table 2. The fluidity of the polymer particles H was somewhat heavy, and the water-absorbing gel had a strong fluidity and a low gel strength. The water absorption rate was also relatively low.

<< Reference Example 9 >>
TBAS-Q (300 g, 70.0 mol%) was added, and 410 g of an aqueous sodium hydroxide solution containing 0.02 g of hydroxy-tetramethyl-1-piperidineoxyl and 34.8 g of sodium hydroxide was added dropwise while cooling from the outside. By neutralizing 60% by mole of TBAS-Q, 2-acrylamido-2-methylpropanesulfone in which 2-acrylamido-2-methylpropanesulfonic acid that has not been neutralized is neutralized by 40% in a molar ratio An aqueous solution containing 60% acid by mole was prepared. Add 44.9 g (30.0 mol%) of acrylamide, 0.15 g of N, N′-methylenebisacrylamide and 0.5 g of ammonium persulfate to this solution and dissolve, then blow out nitrogen gas to drive out dissolved oxygen. Polymer particles I were prepared in the same manner as in Reference Example 5 except that a monomer aqueous solution containing a polymerization initiator and a crosslinking agent prepared in the above was used. The liquid absorption characteristics of the polymer particles L and the state of the water absorbing gel are summarized in Table 2. The resin particles of the polymer particles I had an original appearance and very poor fluidity. Further, the water-absorbing gel was slightly water-glue and strong in fluidity and weak in gel strength.

<< Reference Example 10 >>
TBAS-Q (290 g, 60.2 mol%) and acrylic acid (34.0 g, 20.3 mol%) were added, and 0.02 g of hydroxy-tetramethyl-1-piperidineoxyl was added while cooling from the outside. By adding 410 g of an aqueous solution of sodium hydroxide in which 2 g was dissolved dropwise to neutralize TBAS-Q to 100 mol%, non-neutralized 2-acrylamido-2-methylpropanesulfonic acid had a molar ratio of 0%, An aqueous solution containing 100% molar ratio of 2-acrylamido-2-methylpropanesulfonic acid was prepared. At this time, 75% of acrylic acid was simultaneously neutralized. Add 32.0 g (19.4 mol%) of acrylamide, 0.15 g of N, N′-methylenebisacrylamide, and 0.5 g of ammonium persulfate to this solution and dissolve it, then blow out nitrogen gas to drive out dissolved oxygen. Polymer particles J were prepared in the same manner as in Reference Example 1 except that a monomer aqueous solution containing a polymerization initiator and a crosslinking agent prepared in the above was used. The liquid absorption characteristics of the polymer particles J are summarized in Table 2. The fluidity of the polymer particles J was slightly heavy, and the water-absorbent gel was slightly water-glue and had high fluidity and low gel strength. In the liquid absorption characteristics, the water absorption rate of CaCl ₂ water was particularly low.

<< Reference Example 11 >>
TBAS-Q (15.5 g, 3.0 mol%) and acrylic acid (48.6 g, 27.0 mol%) were added. While cooling from the outside, 0.01 g of hydroxy-tetramethyl-1-piperidineoxyl was added, and hydroxylated. By dropping 410 g of an aqueous sodium hydroxide solution in which 30.0 g of sodium was dissolved to neutralize TBAS-Q to 100 mol%, the unneutralized 2-acrylamido-2-methylpropanesulfonic acid was 0% in molar ratio. An aqueous solution containing neutralized 2-acrylamido-2-methylpropanesulfonic acid in a molar ratio of 100% was prepared. At this time, 100% of acrylic acid was simultaneously neutralized. Prepared by adding 125 g (70.0 mol%) of acrylamide, 0.78 g of N, N'-methylenebisacrylamide, and 0.5 g of ammonium persulfate to this solution and then dissolving the oxygen by blowing in nitrogen gas. Polymer particles K were prepared in the same manner as in Reference Example 5 except that the monomer aqueous solution containing the polymerization initiator and the crosslinking agent was used. The liquid absorption characteristics of the polymer particles K are summarized in Table 2. The fluidity of the polymer particles K was slightly heavy, and the water-absorbing gel had a strong fluidity and a low gel strength. The water absorption rate was also low.

<< Example 1-4 >>
50 parts by weight of the water-absorbent resin of Reference Example 1-4 as the component (A), 100 parts by weight of chloroprene rubber as the component (B), 4 parts by weight of magnesium oxide, 5 parts by weight of zinc oxide, 2- Mercaptoimidazoline 1 part by weight, stearic acid 1 part by weight, 2,2-methylenebis-4-methyl-6-tert-butylphenol 2 parts by weight, calcium carbonate 20 parts by weight and process oil 15 parts by weight on a 10 inch test roll for 20 minutes After kneading, a compound having a thickness of 3.5 mm was obtained. This compound was vulcanized at 170 ° C. for 10 minutes by an electric heating press to obtain a sheet-like water-swellable sealing material of the present invention having a thickness of 3 mm. The swelling properties of this product are shown in Table 3.

<< Comparative Example 1-7 >>
50 parts by weight of the water-absorbent resin of Reference Example 5-11 as component (A), 100 parts by weight of chloroprene rubber as component (B), 4 parts by weight of magnesium oxide, 5 parts by weight of zinc oxide, 2- Mercaptoimidazoline 1 part by weight, stearic acid 1 part by weight, 2,2-methylenebis-4-methyl-6-tert-butylphenol 2 parts by weight, calcium carbonate 20 parts by weight and process oil 15 parts by weight on a 10 inch test roll for 20 minutes After kneading, a compound having a thickness of 3.5 mm was obtained. This compound was vulcanized at 170 ° C. for 10 minutes by an electric heating press to obtain a sheet-like water-swellable sealing material of the present invention having a thickness of 3 mm. The swelling properties of this product are shown in Table 3.

Example 5
A mixture of 25 parts by weight of the water-absorbent resin of Reference Example 1 and 25 parts by weight of a hydrophilic urethane prepolymer (Pandex TP-654, manufactured by Dainippon Ink & Chemicals, Inc.) as the component (A). 100 parts by weight of chloroprene rubber as component (B), 4 parts by weight of magnesium oxide, 5 parts by weight of zinc oxide, 1 part by weight of 2-mercaptoimidazoline, 1 part by weight of stearic acid, 2,2-methylenebis-4 -After compounding with 2 parts by weight of methyl-6-tert-butylphenol, 20 parts by weight of calcium carbonate and 15 parts by weight of process oil for 20 minutes on a 10 inch test roll, a compound having a thickness of 3.5 mm was obtained. This compound was vulcanized at 170 ° C. for 10 minutes by an electric heating press to obtain a sheet-like water-swellable sealing material of the present invention having a thickness of 3 mm. The swelling properties of this product are shown in Table 4.

Claims (7)

Rubber (A),
(I) The sulfonic acid group-containing acrylamide monomer (a) in which the sulfonic acid group is not neutralized and the sulfonic acid group-containing acrylamide monomer (b) in which the sulfonic acid group is neutralized are ) / 20 to 60 mol% of a mixture of sulfonic acid group-containing acrylamide monomers comprising (b) in a molar ratio of 20/80 to 60/40,
(Ii) acrylamide monomer 35-79 mol%,
(iii) a mixture of said monomers containing 5 mol% or less of unneutralized (meth) acrylic acid monomer,
A water-swellable sealing material comprising a water-swellable substance (B) comprising polymer crosslinked copolymer particles obtained by copolymerization. The sulfonic acid group-containing acrylamide monomer (a) is
General formula (1)

(Wherein R ¹ represents a hydrogen atom or a methyl group, X represents —NH—, and R ² represents a linear or branched alkylene group having 2 to 4 carbon atoms). The water-swellable sealing material according to claim 1. The sulfonic acid group-containing acrylamide monomer (b)
General formula (2)

(In the formula, R ¹ is a hydrogen atom or a methyl group, X is —NH—, R ² is a linear or branched alkylene group having 2 to 4 carbon atoms, Y is an alkali metal or alkaline earth metal) Or an ammonium group.) The water-swellable sealing material according to claim 1. The monomer mixture is 20-50 mol% of the sulfonic acid group-containing acrylamide monomer mixture (i), 49-79 mol% of the acrylamide monomer (ii), and is not neutralized. The water-swellable sealing material according to any one of claims 1 to 3, wherein the (meth) acrylic acid monomer (iii) is contained in an amount of 1 mol% or less. The neutralization rate of the sulfonic acid group of the sulfonic acid group-containing acrylamide monomer (b) in which the sulfonic acid group is neutralized is 40 to 80%, according to any one of claims 1 to 4. Water-swellable sealing material. The sulfonic acid group-containing acrylamide monomer (a) in which the sulfonic acid group is not neutralized is 2-acrylamido-2-methylpropanesulfonic acid in which the sulfonic acid group is not neutralized, and the sulfonic acid group is The water-swellable seal according to any one of claims 1 to 5, wherein the neutralized sulfonic acid group-containing acrylamide monomer (b) is an alkali metal salt of 2-acrylamido-2-methylpropanesulfonic acid. Wood. The water-swellable sealing material according to any one of claims 1 to 6, wherein the water-swellable substance comprises a mixture of the polymer crosslinked copolymer particles and a hydrophilic polyurethane prepolymer.