JPH11199857A - Water-swelling composite sealant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject sealant having high durability and suppressed elution of highly water-absorbing resins and other additives, by including, as water-swelling materials, an inner layer consisting of a highly water-absorbing resin and a waterswelling urethane bound to each other and an outer layer containing the water-swelling urethane. SOLUTION: This water-swelling composite sealant consists of (A) a rubber material (natural rubber or synthetic ruber such as chloroprene rubber), (B) a highly water-absorbing resin (e.g. a hydroxy group-containing gelled product of vinyl acetate-methyl acrylate copolymer) and (C) a water-swelling urethane (a liquid water-swelling urethane prepolymer containing 0.5-15% terminal NCO and obtained by reacting a mixture of polyether polyols with an aromatic isocyanate) as the main components, wherein, as water-swelling materials, its inner layer consists of the highly water-absorbing resin and the water-swelling urethane bound to each other and its outer layer contains the water swelling urethane (in the periphery or a part thereof). The weight ratio of inner/outer layers of the sealant is preferably 2-10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-swellable composite sealing material for sealing gaps in various types of civil engineering and construction works for the purpose of, for example, waterproofing or airtightness.

[0002]

2. Description of the Related Art As a water-swellable sealing material, there are many known methods of mixing a rubber material with a superabsorbent resin or water-swellable urethane (for example, JP-B-63-18623, JP-B-63-28107). No., JP-A-64-60
683, JP-A-1-103661, JP-A-2-88619, JP-A-8-157803). Further, for the purpose of improving the durability of the water-swellable sealing material, a water-swellable sealing material is used. BACKGROUND ART A water-swellable composite sealing material in which a non-water-swellable sealing material or a high-water-swelling sealing material and a low-water-swelling sealing material are combined is known. However, these seal materials are inferior in durability and frequently cause water leakage accidents.

[0003]

The high water-swellable sealing material containing a super-water-absorbent resin as a main component has poor durability because the super-water-absorbent resin gradually elutes over a long period of time and the swelling function is reduced. There's a problem. In addition, a low water swellable sealing material containing water swellable urethane as a main component is less common but has a low swelling ratio and a limited range of use, which is not common. The present invention has been made in view of these problems, and it is an object of the present invention to provide a novel water-swellable composite sealing material in which a highly water-absorbent resin is hardly eluted over a long period of time and the swelling ratio can be arbitrarily controlled. I do.

[0004]

[Means for Solving the Problems]

[Summary] In a water-swellable composite sealing material containing a rubber substance, a highly water-absorbent resin, and water-swellable urethane as main components, as a water-swellable substance, the inner layer is a combination of the highly water-absorbent resin and water-swellable urethane. On the other hand, the outer layer (surrounding or a part thereof) is characterized by being coated with a low water swellable sealing material mainly composed of water swellable urethane with little elution. In this case, a part of the water-swellable composite sealing material may be a non-swelling layer, and ribs, embossments, adhesives and the like may be used to improve the adhesiveness with the inner layer. In the water-swellable composite sealing material of the present invention, the ratio between the inner layer and the outer layer, the swelling ratio, and the like can be freely selected depending on the purpose of stopping water, but is usually preferably 2 to 10 times.

[0005]

[Material] Among the materials of the present invention, important matters will be described.

[Rubber substance] The rubber substance used in the present invention is selected from natural rubber and synthetic rubber. As the latter synthetic rubber, for example, chloroprene rubber, butyl rubber, SBR
(Styrene butadiene rubber), acrylic rubber, isoprene rubber, ethylene propylene rubber and the like. These may be vulcanized or unvulcanized.

[0006]

[Superabsorbent resin] The superabsorbent resin usable in the present invention includes a hydroxyl group, a carboxylic acid group, an amide group, an ammonium group, which binds to a terminal isocyanate group of water-swellable urethane.
It is essential that an epoxy group or the like be included. Specifically, a hydroxylated vinyl acetate-methyl acrylate copolymer chelicide, a partially cross-linked carboxylic acid group-containing polyacrylate, a salt of a cross-linked isobutylene-maleic anhydride and a modified product thereof, and an amide A crosslinked product of a group-containing poly (N-vinylacetamide) is exemplified.

[0007]

[Water-swellable urethane] The water-swellable urethane usable in the present invention is generally used for a water-swellable sealing material, and has a general formula R [(OR ₁ ) nOH] p (wherein
R represents a polyhydric alcohol residue; (OR ₁ ) n represents a polyoxyalkylene chain comprising an oxyethylene group and an oxyalkylene group having an alkylene group having 3 to 4 carbon atoms (provided that the proportion of the oxyethylene group is Is the molecular weight of 20-7
N occupying 0%) n is a number indicating the degree of polymerization of the oxyalkylene group, a number corresponding to a hydroxyl equivalent of 500 to 5000, and p is one or two of polyether polyols represented by an integer of 2 to 8. The terminal NCO content obtained by reacting the above mixture with an aromatic isocyanate is 0.5 to 15
% Liquid water-swellable urethane prepolymer. Examples of the polyhydric alcohol include dihydric alcohols (such as ethylene glycol and propylene glycol), trihydric alcohols (such as glycerin and trimerol propane), and tetrahydric alcohols (such as erythritol and pentaerythritol).
Examples thereof include pentahydric alcohols (such as arapit and xylit) and hexahydric alcohols (such as sorbit and mannitol). Examples of the isocyanate compound include 2,4-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, dianisidine isocyanate, tolidine diisocyanate, hexanemethylene diisocyanate, and the like, but are not limited thereto.

[0008]

[Filler] Any commonly used filler such as clay, calcium carbonate, white carbon, carbon black, talc, bentonite and the like can be used.

[0009]

[Method of bonding super water absorbent resin and water swellable urethane]
A method in which a carboxylic acid group, a hydroxyl group, an amide group, an ammonium group, an epoxy group, or the like contained in the superabsorbent resin and the terminal isocyanate group of the water-swellable urethane are bonded at room temperature or by heating. When the liquid water-swellable urethane prepolymer to be used has a high viscosity, it is diluted with an organic solvent such as xylene, and then sufficiently mixed with the superabsorbent resin and easily bonded by stirring. The mixing ratio of the two is a property to be determined from the swelling ratio of the water-swellable sealing material,
In the production of a sealing material requiring a high swelling ratio, it is preferable that the mixing ratio of the superabsorbent resin used for the inner layer is higher than that of the water-swellable urethane.

[0010]

The function of the present invention is to prevent the elution of the superabsorbent resin from the superswellable sealing material used for the inner layer, and to combine the superabsorbent resin with the water-swellable urethane in advance to polymerize the resin.
In addition, the outer layer is covered with a low swelling sealant containing water-swellable urethane with little elution, and a composite structure with excellent durability that can almost completely prevent the elution of the highly water-absorbent resin in the inner layer for a long time. To provide.

[0011]

The present invention will now be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The high water swellable rubber composition of Example 1 is shown in Table 1, and the low water swellable rubber composition with little elution is shown in Table 2.

[0012]

Example 1 A conventional 75φ vent type extruder (L / D = 1)
6) Using two units, the high-water-swellable rubber composition shown in Table 1 was used for the inner layer, and the dimensions were 19 mm width × 4 mm thickness, and the periphery (for the outer layer) was a 75φ vent type extruder (L / D). = 16)
And coated with a 0.5 mm thick low water swellable rubber composition of Table 2 in an indirect vulcanizer at 130 ° C. for 100 minutes, air pressure 3
Vulcanization was performed at kg / cm ² to obtain a water-swellable composite sealing material.

[0013]

Comparative Example 1 A high water swellable rubber composition shown in Table 3 was subjected to a 75 mm vent type extruder (L / D = 16) to obtain a 20 mm width × 5 mm.
It was molded to a thickness and vulcanized under the conditions of Example 1 to obtain a highly water-swellable sealing material.

Comparative Example 2 Next, using the low water swellable rubber composition shown in Table 2, a low water swellable sealing material was obtained in the same manner as in Comparative Example 1.

[0014]

[Measurement of Water Swelling Magnification] Each of the water-swellable sealing materials obtained in Examples and Comparative Examples was cut to a length of 20 mm, immersed in 1 liter of tap water at room temperature, and after 30 days,
The change in volume was measured after and 90 days, respectively, and the swelling ratio (volume) was determined from the calculation formula shown in Table 4 and shown in Table 6.

[0015]

[Measurement of Weight Change Rate of Water-Swellable Sealing Material] Each of the various water-swellable sealing materials obtained in Examples and Comparative Examples was measured for 2 parts each.
Cut to 0 mm length, immersed in 1 liter of tap water at room temperature, taken out after 30, 60 and 90 days.
The sample was placed in a thermostat at 0 ° C., dried until a constant weight was obtained, the change in weight of each sample was measured, and the rate of change in weight was calculated from the calculation formula shown in Table 5 and shown in Table 7.

From the results of the Examples and Comparative Examples, it can be seen that the amount of the superabsorbent resin dissolved in Example 1 is clearly smaller than that of Comparative Example 1.

[0017]

As described above, the water-swellable composite sealing material according to the present invention is excellent in durability and environmentally friendly because the amount of the highly water-absorbing resin dissolved out over a long period of time is smaller than conventionally known ones. It provides a water-swellable sealing material and can greatly contribute to the development of civil engineering and construction fields.

[0018]

[Brief explanation of the table]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

[Table 7]

Claims (3)

[Claims] 1. A water-swellable composite sealing material comprising a rubber substance, a highly water-absorbent resin and water-swellable urethane as main components, wherein the inner layer is a water-swellable resin and a water-swellable urethane as the water-swellable substance. Wherein the outer layer (its periphery or a part thereof) contains water-swellable urethane. 2. The water-swellable composite sealing material according to claim 1, wherein a material in which a superabsorbent resin and water-swellable urethane are previously bonded is used for the inner layer. 3. The water-swellable composite seal material according to claim 1, wherein the water-swellable composite seal material contains water-swellable urethane in an outer layer (around or a part of the outer layer).