JPH0649830B2 - Salt resistant water swelling material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a water swelling material useful as a sealing material or the like for filling and sealing gaps of various structures. More specifically, salt-resistant water useful as a water-stopping material, etc., which can absorb and swell even an aqueous liquid containing a high concentration of salt, thereby completely preventing leaching of the aqueous liquid from the outside or the inside. Regarding swelling material.

(Prior Art) Conventionally, many techniques have been proposed in which a water-absorbent resin is dispersed in a thermoplastic resin or rubber to prepare a water-swellable composition, and the water-swellable composition is used as the water-stopping material.

However, all of them have poor salt resistance, and when they come into contact with an aqueous liquid containing a high concentration of a salt, especially a polyvalent metal ion, or an aqueous liquid containing a novel salt continuously at a low concentration for a long period of time. Has a drawback that the swelling rate decreases and a sufficient water blocking effect cannot be exhibited.

(Problems to be Solved by the Invention) As a result of intensive studies, the present inventors have improved the above-mentioned drawbacks and developed a salt-resistant water-swelling material having a sufficient swelling rate even when contacted with an aqueous liquid containing salt. The present invention has been completed.

(Means and Actions for Solving Problems) That is, the present invention has the general formula (However, R ¹ is hydrogen or a methyl group, and R ² has 2 to 4 carbon atoms.
, X is hydrogen, an alkali metal, an alkaline earth metal, an ammonium group, or a substituted ammonium group. ) Unsaturated sulfonic acid group-containing monomer (A)
A water-absorbent resin (I) obtained by polymerizing a monomer component that essentially contains (C) in the presence of a crosslinking agent (B) is dispersed in a base material (II) made of a thermoplastic resin and / or rubber. The present invention provides a salt-resistant water swelling material.

Sulfonic acid group-containing unsaturated monomer used in the present invention (A)
(Hereinafter, referred to as a monomer (A).) Is represented by the above general formula, for example, 2-acrylamido-2-methylpropanesulfonic acid, 2-acrylamido-2-ethylpropanesulfonic acid, acrylamide. Unsaturated sulfonic acids such as methyl sulfonic acid and acrylamidoethyl sulfonic acid, their alkali metal salts, alkaline earth metal salts,
Examples thereof include ammonium salts and substituted ammonium salts, and one or more of these can be used.

Water-absorbent resin (I) used in the present invention may be obtained by polymerizing the monomer (A) alone, but other water-soluble monomers (C)
It may be used in combination with and copolymerized. Examples of the other water-soluble monomer (C) (hereinafter referred to as the monomer (C)) include acrylic acid or its alkali metal salt or ammonium salt, methacrylic acid or its alkali metal salt or ammonium salt, etc. And one or more of these can be used. The ratio of the monomer (C) used is preferably 90 with respect to the total amount of the monomer (A) and the monomer (C).
The proportion is preferably not more than 60% by weight, more preferably not more than 60% by weight. If the amount of the monomer (C) used exceeds 90% by weight, the salt resistance of the resulting water absorbent resin (I) may be deteriorated.

Further, even if a water-insoluble monomer is copolymerizable with the monomer (A) and the monomer (C), it does not significantly reduce the water absorbing ability of the resulting water absorbent resin (I). It can be used in a range. The combined use of water-insoluble monomers may be preferable in order to improve the affinity between the water-absorbent resin (I) and the substrate (II) to be obtained.

Examples of the crosslinking agent (B) used in the present invention include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth)
A compound having two or more ethylenically unsaturated groups in one molecule such as acrylate, pentaerythritol di (meth) acrylate, N, N'-methylenebisacrylamide, triallyl isocyanurate, and trimethylolpropane diallyl ether can be used. .

When the monomer (C) contains an unsaturated carboxylic acid,
Polyhydric alcohols such as ethylene glycol, triethylene glycol, dipolyethylene glycol, glycerin, polyglycerin, propylene glycol, diethanolamine, triethanolamine, polyvinyl alcohol, pentaerythritol, sorbit, sorbitan, glucose, mannitol, mannitol sucrose and glucose;
Ethylene glycol diglycidyl ether, glycerin diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,
Epoxy compounds such as 6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, trimethylolpropane triglycidyl ether, and glycerin triglycidyl ether are listed, and one or more of these may be appropriately selected and used. it can. When a polyhydric alcohol is used as the cross-linking agent (B), it is preferable to perform post-polymerization heat treatment at 150 ° C to 250 ° C, and when using a polyepoxy compound, at 50 ° C to 250 ° C. The amount of the cross-linking agent (B) used is preferably in the range of 0.00001 to 0.1 in terms of molar ratio with respect to the total amount of the monomer components essentially containing the monomer (A). .

The polymerization method for obtaining the water absorbent resin (I) in the present invention,
Any conventionally known method may be used, including a method using a radical polymerization catalyst, a method of irradiating with radiation, an electron beam, ultraviolet rays, and the like. Radical polymerization catalysts include peroxides such as hydrogen peroxide, benzoyl peroxide, cumene hydroperoxide; azo compounds such as azobisisobutyronitrile; radical generation of persulfates such as ammonium persulfate and potassium persulfate. A redox initiator is used which is an agent or a combination thereof with a reducing agent such as sodium bisulfite, L-ascorbic acid and ferrous salt.

As the polymerization solvent, for example, water, methanol, ethanol, acetone, dimethylformamide, dimethylsulfoxide, or the like, or a mixture thereof can be used. The temperature at the time of polymerization varies depending on the type of the polymerization catalyst used, but a relatively low temperature is preferable because the molecular weight of the crosslinked polymer increases. However, in order to complete the polymerization, 20 ° C or higher and 10
It is preferably in the range of 0 ° C or lower. The concentration of the monomer in the polymerization system is not particularly limited, but is preferably 20 to 60% by weight in consideration of the ease of control of the polymerization reaction and the yield. Although various forms of polymerization can be adopted, a method of polymerizing while subdividing the hydrogel polymer by shearing force of reverse phase suspension polymerization, cast polymerization, or double arm type kneader (JP-A-57-
34101) is preferred.

Base material (II) in which the water-absorbent resin (I) is dispersed in the present invention
Can be appropriately selected and used from various thermoplastic resins and / or rubbers.

Examples of the thermoplastic resin used in the present invention include ethylene-vinyl acetate copolymers, saponified ethylene-vinyl acetate copolymers, ethylene-isobutylene copolymers, ethylene-acrylic acid salt copolymers, vinyl chloride copolymers. Examples include coalesced materials, polyurethane, polyethylene, polypropylene, polystyrene, ABS resin, polyamide polyvinyl acetate and the like. Examples of the rubber include ethylene-propylene rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene copolymer rubber, chloroprene rubber, fluororubber, silicon rubber, urethane rubber,
Examples thereof include polysulfide rubber, acrylic rubber, butyl rubber, epichlorohydrin rubber, and natural rubber. The salt-resistant water-swelling material of the present invention is obtained by uniformly dispersing the water-absorbent resin (I) in the base material (II) made of a thermoplastic resin and / or rubber by mechanical methods. The dispersion method is not particularly limited, for example, a method of kneading the water-absorbent resin (I) and the base material (II) with a commonly used mixing device such as a roll or a Banbury mixer, to form the base material (II). Examples include a method in which the water-absorbent resin (I) is dispersed in a monomer or a prepolymer and then a polymerization or curing reaction is performed. The preferred blending ratio of the water absorbent resin (I) to the base material (II) in the salt-resistant water-swelling material of the present invention varies depending on the type of the base material (II) used and the dispersion method of the water absorbent resin (I). Although it cannot be said, it is generally 5 to 300 parts by weight of the water absorbent resin (I) with respect to 100 parts by weight of the base material (II). When the amount of the water-absorbent resin (I) is less than 5 parts by weight, it is not possible to obtain a water-swelling material having a sufficient swelling ratio when contacted with an aqueous liquid. Also, 3
If it exceeds 100 parts by weight, the strength of the resulting water-swelling material becomes weak and the water-absorbing gel drops off remarkably, so that a stable performance for a long period cannot be obtained.

The water swelling material of the present invention includes fillers such as carbon black, calcium silicate, calcium carbonate, zinc oxide and clay; modifiers such as rosin, petroleum resin, coumarone resin and phenol resin; sulfur, polysulfide rubber and the like. Vulcanizing agent; 2-mercaptobenzothiazole, dibenzothiazyl disulfide and other vulcanization accelerators; stabilizers; antioxidants; pigments; processing aids; plasticizers and the like. Further, the water swelling material of the present invention may be molded into a desired shape by various molding methods such as press molding.

(Effect of the invention) The salt-resistant water-swelling material of the present invention obtained as described above,
Since it greatly swells even when it comes into contact with an aqueous liquid containing a high concentration of salt, it can be used to prevent water retention or passage of an aqueous liquid containing salt, especially seawater. Therefore, for example, it can be effectively used as a seal between segments for tunnel construction, a seal for a fume pipe connection portion, a water retaining bed for agriculture and horticulture, a medical hygiene material, and the like. In addition, since the amount of water-soluble substances eluted from the water swelling material is small, it is not only used as a waterproofing material for civil engineering, waterproofing material between segments for tunnel construction, industrial sealing material, etc., but also as a waterproofing material and sealing material for waterworks. It can be effectively used as a water retention bed for gardening, medical hygiene materials, etc.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited to these Examples.

Example 1 Sodium 2-acrylamido-2-methylpropanesulfonate 183.
2g (0.8mol), acrylic acid 3.6g (0.05mo
l), sodium acrylate 14.1g (0.15mo
l), N, N'-methylenebisacrylamide 0.15
4 g (0.001 mol) and 260 g of water were charged and stirred to dissolve uniformly.

After replacing the inside of the flask with nitrogen, heat to 40 ° C in a water bath,
1.0 g of a 10% sodium persulfate aqueous solution and 0.5 g of a 1% L-ascorbic acid aqueous solution were added, and the stirring was stopped to perform polymerization. After the initiation of polymerization, heat was generated, and 40 minutes later, the temperature rose to 68 ° C. When the rise in the liquid temperature stops, the bath temperature is set to 90 ° C.
The temperature was raised to 40 ° C., and aging was performed for 40 minutes. The obtained polymer was subdivided, dried with hot air at 150 ° C. for 3 hours, and pulverized to obtain a water absorbent resin (1).

80 g of the obtained water absorbent resin (1) and ethylene-vinyl acetate
Copolymer (Evaflex , Mitsui Polychemical Company
(Made in Japan) 100g after kneading with a roll for 15 minutes
Pressed with, and molded into a sheet with a thickness of 1 mm
A bright salt-resistant water swelling material (1) was obtained.

Comparative Example 1 Acrylic acid 1 was added to a 500 ml cylindrical separable flask.
8.0 g (0.025 mol), sodium acrylate 7
0.5 g (0.75 mol), N, N'-methylenebisacrylamide 0.154 g (0.001 mol) and water 1
21 g was charged, and a 10% ammonium persulfate aqueous solution was prepared.
Comparative water absorbent resin (1) was obtained by polymerizing, drying and pulverizing in the same manner as in Example 1 using 0 g and 0.5 g of 1% L-ascorbic acid aqueous solution.

80 g of the obtained water absorbent resin (1) and ethylene-vinyl acetate
Copolymer (Evaflex , Mitsui Polychemical Company
100 g) were mixed and pressed in the same manner as in Example 1.
The comparative water swelling material (1) molded into a 1 mm thick sheet
Obtained.

Example 2 220 ml of n-hexane was added to a 500 ml four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a nitrogen gas inlet pipe.
Was charged, 1.8 g of sorbitan monostearate was added and dissolved, and then the atmosphere was replaced with nitrogen. 22.9 g (0.10 mol) of sodium salt of 2-acrylamido-2-methylpropanesulfonic acid and 4.3 g of methacrylic acid were added to the dropping funnel.
(0.05 mol), trimethylolpropane triacrylate 0.0296 (0.0001 mol), 50 g of water and 0.05 g of potassium persulfate were added to form a uniform aqueous solution, and then nitrogen gas was blown into the solution to generate oxygen present in the aqueous solution. Was removed. Then, the contents of the dropping funnel were added to the four-necked flask and dispersed therein, and while slightly introducing nitrogen gas, the temperature of the polymerization system was kept at 60 to 65 ° C. by a water bath and the polymerization reaction was continued for 3 hours. . Then, n-hexane was distilled off under reduced pressure, and the residue was heated and dried to obtain a water absorbent resin (2).

35 g of the resulting water absorbent resin (2), polyetherpolol (EP-550H, manufactured by Mitsui Nisso Urethane Co., Ltd.) 100
g, silicone surfactant (F-258, manufactured by Shin-Etsu Chemical Co., Ltd.)
A composition obtained by mixing 2 g, tin octylate 0.15 g, water 2 g and tolylene diisocyanate 30.8 g,
By curing in a petri dish having a diameter of 20 mm and a height of 5 mm, a disc-shaped salt-resistant water swelling material (2) of the present invention was obtained.

Example 3 Sodium salt of 2-acrylamido-2-methylpropanesulfonic acid 9 in a 500 ml cylindrical separable flask 9
1.6 g (0.40 mol), methacrylic acid 30.1 g
(0.35mol), sodium methacrylate 27.0g
(0.25 mol), glycerin 0.46 g (0.005 m
ol) and 190 g of water were charged, and polymerization was carried out in the same manner as in Example 1 using 1.0 g of a 10% ammonium persulfate aqueous solution and 0.5 g of a 1% L-ascorbic acid aqueous solution. The water-containing gel of the water-absorbent resin obtained was subdivided, dried at 180 ° C. for 2 hours, and pulverized to obtain a water-absorbent resin (3).

60 g of the resulting water absorbent resin (3), 10 chloroprene rubber
0 g, zinc white (No. 1) 5 g, magnesium oxide 4 g, stearic acid 1 g, P, P'-diaminodiphenylmethane (anti-aging agent) 2 g and 2-mercaptobenzothiazole (vulcanization accelerator) 2 g were kneaded with a roll for 15 minutes. After doing
It was press-vulcanized at 150 ° C. for 10 minutes to obtain a salt-resistant water-swelling material (3) of the present invention molded into a sheet having a thickness of 1 mm.

Example 4 The same four-necked flask used in Example 2 was charged with 250 ml of cyclohexane, 2.0 g of sorbitan monostearate was added and dissolved, and then the atmosphere was replaced with nitrogen. Into the dropping funnel, 40.4 g (0.2 mol) of sodium salt of 2-acrylamido-2-methylpropanesulfonic acid, 0.0428 g (0.000 g) of diethylene glycol diacrylate.
2 mol), 50 g of water and 0.1 g of potassium sulphate were added to form a uniform aqueous solution, and then nitrogen gas was blown into the solution to remove oxygen existing in the aqueous solution. Then, the contents of the dropping funnel were added to the four-necked flask and dispersed therein, and Example 2
After carrying out the polymerization reaction in the same manner as in (1), cyclohexane was distilled off, and the hydrogel was dried under reduced pressure at 80 ° C to obtain a water-absorbent resin (4).
Got

20 g of the water absorbent resin (4) thus obtained and ethylene-vinyl acetate
Copolymer (Evaflex , Mitsui Polychemical Company
(Made in Japan) 25 g on a roll for 15 minutes, then at 100 ° C
The present invention formed by pressing into a sheet having a thickness of 1 mm
A salt-resistant water swelling material (4) was obtained.

Example 5 20 g of the water absorbent resin (1) obtained in Example 1 and ethylene
-Vinyl acetate copolymer (Eva Flex , Mitsui Polique
Using 100 g (manufactured by Mikaru) in the same manner as in Example 1.
And the salt-resistant water swelling of the present invention formed into a sheet having a thickness of 1 mm.
A lumber (5) was obtained.

Example 6 100 g of the water absorbent resin (1) obtained in Example 1 and ethyl
-Vinyl acetate copolymer (Evaflex , Mitsui Poly
(Chemical company) 40 g
And a salt-resistant water swell of the present invention formed into a sheet having a thickness of 1 mm.
A lumber (6) was obtained.

Example 7 Salt-resistant water-swelling material obtained in Examples 1 to 6 and Comparative Example 1
Using (1) to (6) and the comparative water swelling material (1) as test pieces, the water swelling rate was measured.

The water swelling ratio was measured by immersing each test piece in 2000 ml of synthetic seawater having the composition shown in Table 1 for 24 hours, and then taking it out.
The measurement was performed by measuring the ratio of the volume of the test piece after the immersion to the volume before the immersion. The results are shown in Table 2.

Claims (1)

[Claims] 1. A general formula (However, R ¹ is hydrogen or a methyl group, and R ² has 1 to 5 carbon atoms.
, X is hydrogen, an alkali metal, an alkaline earth metal, an ammonium group, or a substituted ammonium group. ) Unsaturated sulfonic acid group-containing monomer (A)
A water-absorbent resin (I) obtained by polymerizing a monomer component that essentially contains (C) in the presence of a crosslinking agent (B) is dispersed in a base material (II) made of a thermoplastic resin and / or rubber. Salt resistant water swelling material.