JPH09207258A - Cut-off agent and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a water path from being generated in a cut-off agent layer, if a large quantity of water flows in by arranging a water permeable sheet on both surfaces of the cut-off agent layer laminated in such a manner that a water-absorbing material whose water-absorptive rate is the highest among two or more different water-absorbing materials whose water-absorbing rates are different, is located on at least, one of the surfaces of the cut-off agent layer. SOLUTION: An adhesive is applied to a needle punching unwoven fabric 1A as a water-permeable sheet, then sodium polyacrylate 2A with high water- absorbing rate is sprayed over the adhesive coat, and a reinforcing sheet 3A is laid over this sodium polyacrylate 2A. In addition, bentonite 5 with a low water-absorbing rate is sprayed over the reinforcing sheet 3A and the bentonite layer 5 is lightly pressed with a roll 16. Further, a composite sheet 3B is the needle punching unwoven fabric 1B and the sodium polyacrylate 2B is laminated on the bentonite layer 5 in such a manner that the sodium polyacrylate 2B is set to face the bentonite layer 5. Finally, this laminate is subjected to a needle punching process and the adhesive is cured to obtain the cut-off agent 6.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to the bottom of a pond or river,
The present invention relates to a water blocking material used for waterproofing an inclined surface or a revetment portion, or for water blocking in civil engineering work such as construction of an underground structure, or for blocking wastes.

[0002]

2. Description of the Related Art In recent years, as a water blocking material suitable for the above-mentioned applications, a three-layer structure having upper and lower water-permeable sheets and a water blocking agent positioned in an intermediate layer is generally used. It's starting. For example, Japanese Patent Application Laid-Open No. 60-240446 proposes a waterproof sheet in which particles of a water-absorbent gelling substance are adhesively fixed between water-permeable sheets. In addition, JP-A-3
-59154 and Japanese Patent Laid-Open No. 4-216929 disclose a waterproof sheet in which an inorganic water-absorbing substance is interposed between two upper and lower fiber layers made of a non-woven fabric or the like, and needle punching is performed on the inorganic water-absorbing substance. Is disclosed.

Bentonite, which is a swelling clay substance, is mentioned as a preferable example of the water-absorbing substance positioned in the intermediate layer in any of the water-stopping materials. This bentonite swells about 8 to 10 times and exerts a good water-stopping effect, absorbs water containing salt, and is suitable for construction near the coast, and has low cost.
For these reasons, it is preferred.

[0004]

However, the water stopping material having bentonite as an intermediate layer has the following problems. That is, since bentonite has a low water absorption rate, it is suitable for absorbing water that has gradually exuded from the ground, but as in the case of being constructed at the bottom of a pond or river, a large amount of water is injected after laying. When the bentonite layer flows into the bentonite layer, a “water channel” is formed in the bentonite layer before the bentonite layer is sufficiently swollen, and the layer thickness becomes uneven. As a result, the water pressure resistance of the water blocking material is lowered, and there is a problem that a sufficient water blocking effect cannot be exhibited.

In order to avoid such a problem, it is sufficient to use a water-absorbing substance having a high water absorption rate such as a polymer absorber, but the polymer absorber absorbs water and has a volume of 100 to 1 of its own.
Since it swells 000 times or more, peeling may occur between the upper and lower fibrous sheets. When peeling occurs, for example, when a waterproof material is laid on the inclined surface,
The waterproofing agent layer becomes a sliding surface, which causes the ground located on the upper surface of the waterproofing material to slide, which is not preferable. In addition, the polymer absorber
Its high cost makes it unsuitable for use in large construction sites.

Further, in the case where the water-permeable sheet and the water-absorbent substance are fixed with an adhesive, such as the water blocking material described in JP-A-60-240446, earth and sand are thrown in after laying. When pressure is applied to the water blocking material, partial peeling easily occurs between the water permeable sheet and the water absorbing substance.
As a result, a free space is partially formed in the water blocking material, and water is likely to concentrate in that portion, which causes a problem that the formation of water channels is further promoted.

On the other hand, the one in which each layer is joined by needle punching as described in JP-A-3-59154 and JP-A-4-216929 has the above-mentioned problem when an adhesive is used. There is no problem. However, this water blocking material has a problem that the water blocking agent easily passes through between the fibers and is scattered to the outside of the fiber layer due to an impact force applied at the time of needle punching treatment or construction. The scattering of the waterproofing agent impairs the smooth progress of the needle punching process and the laying work. Further, it is not economically preferable because it is necessary to prepare a waterproofing agent in consideration of the scattered amount. Further, if the water blocking agent is scattered in a large amount, unevenness in the thickness of the water blocking agent may be caused, and the water blocking function may be partially deteriorated.

The present invention has been made in order to solve the above-mentioned problems and does not form a water groove even when a large amount of water flows in, and the water-stopping agent is scattered even if needle punching is applied. The purpose is to provide a small amount of waterproof material.

[0009]

The water-stopping material of the present invention comprises two or more water-absorbing substances having different water-absorbing speeds laminated so that the water-absorbing substance having the highest water-absorbing speed is located on at least one surface. A coating material made of a water-permeable sheet is disposed on both surfaces of the water blocking agent layer. According to this structure, even if a large amount of water flows in, the water-absorbing substance having a high water-absorption rate quickly absorbs the water, so that no water channel is formed. On the other hand, a water-absorbing substance having a low water-absorption rate absorbs water and swells even after the water-absorbing substance having a high water-absorption rate is saturated, so that the presence of such a water-absorbing substance makes the water-stopping effect of the entire water-stopping material long-term. It can be demonstrated over a period of time.

In the above water-stopping material, the water-stopping agent layer includes a water-absorbing substance made of an inorganic substance (hereinafter sometimes abbreviated as an inorganic water-absorbing substance) and a polymer absorber, and a polymer absorber. It is desirable that they are laminated so as to be located on at least one surface. If such a water blocking material is laid and constructed so that water flows in from the surface of the polymer absorbent, the polymer absorbent quickly absorbs a large amount of water and swells,
It is possible to prevent the formation of water lines in the water blocking agent layer. On the other hand, the inorganic water-absorbing substance, after a large amount of water is absorbed by the polymer absorber, gradually absorbs the invading water and swells to form a water-stop layer, which has a long-term water-stopping effect. secure.
In addition, since the volumetric increase of the inorganic water-absorbing substance due to swelling is smaller than that of the polymer absorbent, by using it together, excessive swelling of the entire waterproofing agent layer is suppressed. Further, the use of the inorganic water-absorbing substance is advantageous in terms of cost.

In the above water-stopping material, an adhesive is used between each layer of water-absorbing substances constituting the water-stopping agent layer or between some layers and / or between the water-stopping agent layer and the covering material. It is preferable that the water-stopping agent layer and the covering material are connected by needle punching. In such a water blocking material, the water blocking agent is firmly held between the coating materials by the adhesive and needle punching, so that delamination of the water blocking agent and scattering of the water blocking agent are suppressed.

A preferred method for producing the above water-stopping material is that a composite sheet obtained by laminating and fixing a polymer absorber on one surface of an inorganic water-absorbing substance layer on one surface of a water-permeable sheet with an adhesive is used. Laminating so that it is on the outside, and only the water-permeable sheet on the other side, or the composite sheet is laminated so that the water-permeable sheet is on the outside, and needle punching is performed while the adhesive in the composite sheet does not solidify. This is a method in which the treatment is integrated. According to this method, the non-solidified adhesive prevents the water blocking agent from scattering during the needle punching process. In the water blocking material produced by this method, a part of the adhesive penetrates into the water blocking agent layer by needle punching and solidifies to firmly grip the water blocking agent. Therefore, the use of this water blocking material also prevents the water blocking agent from scattering during the construction work. Hereinafter, the present invention will be described specifically.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The water-stopping material of the present invention comprises a water-stopping agent layer composed of two or more water-absorbing substances having different water-absorption rates, and the water-absorbing substance having the highest water-absorption rate is located on at least one surface. To be laminated. When a substance with a high water absorption rate is laminated on only one surface, it is necessary to lay and construct so that water will flow in from that side, so for example It is preferable to color the coating material or to mark the coating material to facilitate discrimination at the construction site. Further, in order to avoid the troublesomeness of such discrimination, it is possible to stack water-absorbing substances having a high water-absorption rate so as to be located on both sides.

The water blocking agent layer may be composed of only two kinds of substances having a high water absorption rate and a substance having a lower water absorption rate, and it is possible to form a water absorption rate gradient for many kinds of water absorbing substances. Multiple layers may be stacked. However, it should be kept in mind that stacking many kinds of water-absorbing substances leads to an increase in manufacturing cost. The above-mentioned purpose, even when the waterproofing agent layer is formed of only two kinds of water-absorbing substances,
Fully achieved.

In the present invention, it is desirable to use a polymer absorber as the water-absorbing substance having a high water-absorbing rate, and laminate it so that it is located on at least one surface of the inorganic water-absorbing substance. Since all of them are commonly used substances and are easily available, they are preferable as materials for forming a wide area sheet-like material as in the present invention.

As the polymer absorber, CMC, salts of polyacrylic acid, polyvinyl alcohol, polyacrylonitrile and the like which can absorb 50 to 1000 times as much water as its own weight can be used. The polymer absorber may be used in the form of powder or granules, and the size (diameter) of the particles is preferably 0.1 to 1 mm in the dry state.
If it is less than 0.1 mm, it becomes powdery, which makes it difficult to fix it to the covering material with needle punching or an adhesive.
If it exceeds 1 mm, the volume when absorbing water and swelling becomes too large, which may cause peeling from the coating material. Also, due to excessive swelling of the polymer absorber, the thickness of the adjacent inorganic water absorbing substance decreases. Then, the thickness distribution becomes uneven, which is not preferable.

The polymer absorbent preferably has a layer of ^{20 to} 80 g / m ² on one or both surfaces. Even if an attempt is made to form a layer of less than 20 g / m ^2, it is difficult to evenly distribute the polymer absorber,
Since coarseness and denseness occur, water channels are likely to be formed in the rough portion of the polymer absorber. If it exceeds 80 g / m ² , the effect of volume increase due to swelling of the polymer absorbent cannot be ignored, and there is a risk of causing peeling from the coating material, for example. Also, the use of a large amount of polymer absorber leads to high cost.

Next, as the inorganic water-absorbing substance, bentonite, beidellite, nontelonite, saponite, hectorite of the montmorillonite genus, and attapulgite, sepiolite of the holmite genus are used as natural or synthetic substances of swelling clay minerals. It is desirable to do. These clay minerals are also preferably used in the form of powder or granules, and the size of the particles is preferably 200 to 350 mesh (diameter about 74 to 44 μm) in a dry state. If it is less than 200 mesh, the water absorption capacity becomes small, and if it is more than 350 mesh, it is not preferable because fine ones easily pass through the fiber gaps of the water permeable sheet and scatter to the outside. Also, the use of fine clay minerals leads to high costs.

In the waterproofing agent layer, the layer thickness of the inorganic water-absorbing substance is 3 to
8mm is recommended. If the layer thickness is less than 3 mm, it is not preferable because a sufficient water blocking function is not exhibited. Further, the larger the layer thickness is, the better the waterproof function is, but if it is too thick, the needle will be damaged during the integration with the coating material layer by the needle punching treatment described later, and the like. Will be difficult. Therefore, it is desirable that the layer thickness is 8 mm or less.
In order to obtain a layer having a thickness within such a range, it is preferable to use 1 to ⁵ kg of an inorganic water-absorbing substance per 1 m ² .

In the present invention, a water permeable sheet is used to coat the water blocking agent layer. As the water-permeable sheet, for example, a non-woven fabric in which fibers are entangled with each other by needle punching a fiber web having a unit weight of 200 to 500 g / m ² made of synthetic fiber having a fineness of 2 to 15 denier and a fiber length of 50 to 90 mm is used. Good. Here, the type of synthetic fiber is not particularly limited, and for example, fibers made of polypropylene, polyethylene, polyester, polyamide and the like can be used alone or in combination of two or more. Further, in this needle-punched nonwoven fabric, it is desirable that its water permeability is 1 × 10 ⁻² to 1 × 10 ⁻³ cm / sec. When it exceeds 1 × 10 ^-2 cm / sec, the water blocking agent easily passes through the fiber gaps and is scattered, which is not preferable. Further, the smaller the water permeability is, the more the waterproofing agent is prevented from scattering. However, in order to obtain a water blocking agent of less than 1 × 10 ⁻³ cm / sec, it is necessary to increase the number of times of needle punching on the fiber web. This leads to higher costs.

Next, a method for producing the water blocking material of the present invention will be described. The water blocking material of the present invention can be manufactured by any conventionally known method. For example, as described in JP-A-60-240446, the waterproof agent layer and the covering material may be integrated by bonding with an adhesive. In addition, as described in JP-A-3-59154 and JP-A-4-216929,
A method in which a laminate of the waterproofing agent layer and the coating material is subjected to a needle punching process to entangle the fibers constituting the coating material between the upper and lower sides, and the waterproofing agent is held by the entanglement may be adopted.

However, in the present invention, in order to further suppress the scattering of the water blocking agent and strengthen the bond between the layers, it is desirable to manufacture the water blocking material by the following method.

First, an adhesive is applied to one surface of a water-permeable sheet as a covering material, and a polymer absorber is sprinkled on the adhesive to form a composite sheet in which the both are bonded. At this time, it is preferable to use a starch-based or polyvinyl alcohol-based water-soluble adhesive as the adhesive. The amount of the adhesive used is not particularly limited and is determined depending on the form of the water permeable sheet and the amount of the polymer absorber used. For example, in the case of adhering and fixing a polymer absorber having a weight of ^{20 to} 80 g / m ² to a coating material, an adhesive having a polyvinyl alcohol solid content of 20 to 50% may be applied at 100 to 500 g / m ² .

Subsequently, this composite sheet is laminated on one or both surfaces of the inorganic water-absorbing substance. When the composite sheet is laminated on only one surface, the water permeable sheet is laminated on the other surface. At this time, it is essential that the composite sheet is laminated so that the polymer absorber side faces the inorganic water-absorbing substance. Moreover, it is necessary to stack the composite sheets before the adhesive applied to the water-permeable sheet is solidified. Further, before laminating the composite sheets, an adhesive may be applied to the surface of the inorganic water-absorbing substance layer, and the adhesive may be interposed between the polymer absorber and the inorganic water-absorbing substance.

Next, the laminate is subjected to needle punching treatment. In the present invention, it is important to perform needle punching before the adhesive solidifies. By performing the needle punching treatment in a state where the adhesive is wet, it is possible to suppress the scattering of the water blocking agent. Further, while the adhesive is not solidified, since the adhesive has fluidity, a part of the adhesive easily penetrates into the water blocking agent layer or the covering material by needle punching. Then, the invading adhesive solidifies in the waterproofing agent layer and firmly grips the waterproofing agent, so if the waterproofing agent obtained by such a method is used, the scattering of the waterproofing agent at the time of construction is also suppressed. Will be done.

By the needle punching process, some of the fibers constituting the water permeable sheet may enter the water blocking agent layer, or the water absorbing substances may enter each other's layers and the boundaries thereof may become unclear. However, if the presence of each layer is recognized when the entire waterproofing material is viewed, it is included in the concept of “lamination” in the present invention even if the boundary line between them is not clear.

In the water blocking material of the present invention, a reinforcing sheet may be interposed between the water blocking agent layer and the covering material or between the layers of the water absorbing substance layer for reinforcement. As the reinforcing sheet, a woven fabric obtained by weaving uniaxially stretched polypropylene film tape yarns in warp and weft is conveniently used in terms of strength and cost.

Further, in the present invention, the water blocking material obtained by the needle punching treatment may be sewn with a sewing machine. By using the sewing machine together, the upper and lower covering materials are more firmly joined, and the waterproofing agent layer located in the middle is also more firmly gripped. The perforation may be carried out, for example, so that the perforations are in a grid pattern, or the perforations are curved.

[0029]

The present invention will be described below with reference to examples. The water-permeable sheet, water blocking agent, adhesive, and reinforcing sheet used in the examples are as follows.

[Water-permeable sheet] 70% by weight of polyester fiber having a fineness of 8 denier and a fiber length of 64 mm is mixed with 30% by weight of polyester fiber having a fineness of 3 denier and a fiber length of 51 mm to form a card web having a basis weight of 150 g / m ^2. Created.
Then, a two-layered product was subjected to needle punching treatment to produce a nonwoven fabric having a basis weight of 200 g / m ² and a thickness of 2.5 mm, which was used as a water-permeable sheet. The fiber density of this non-woven fabric was 0.08 g / cm ³ , and the water permeability was 5 × 10 5.
^-3 cm / sec.

[Water Stopper] Sodium polyacrylate having a particle size of 0.3 to 0.6 mm is used as a water-absorbing substance having a high water-absorption rate, and a water-absorbing substance having a smaller water-absorption rate is used.
A 250-mesh bentonite was prepared.

[Adhesive] An adhesive prepared by dissolving polyvinyl alcohol in water at a solid content of about 30% was prepared.

[Reinforcing Sheet] A woven fabric was prepared by weaving a uniaxially stretched polypropylene tape film yarn having a width of 2 mm and arranging it on the weft.

<Example 1> A water blocking material was manufactured using an apparatus as shown in FIG. First, the needle punching non-woven fabric (1A), which is a water permeable sheet, is placed on the conveyor (11), and 200 g of the adhesive is applied onto the conveyor (11) using the coating roll (12).
/ M ² applied, and using a roll (13), spray sodium polyacrylate (2A) at a rate of 40 g / m ² to integrate the non-woven fabric (1A) and sodium polyacrylate (2A) The composite sheet (3A) was prepared. Then, composite sheet
On the sodium polyacrylate (2A) of (3A), the reinforcing sheet (4) is fed from the roll (14) and superposed,
Bentonite (5) on it, using roll (15), about 3kg
/ M ² was sprayed, and the bentonite layer (5) was lightly pressed by a roll (16) in order to level it. Furthermore, on it, manufactured in the same method as described above in another place,
A composite sheet (3B) of needle punched nonwoven fabric (1B) and sodium polyacrylate (2B) was laminated so that sodium polyacrylate (2B), bentonite and (5) faced each other.

Subsequently, while the adhesive in the composite sheets (3A) (3B) is not solidified, needle punching treatment is performed using a needle punching machine (17), and the upper and lower nonwoven fabrics (1A) (1B) The constituent fibers were entangled with each other to bond the layers. The needle punching conditions at this time are 1.1 needle density / c
The m2 was ² , the needle depth was 18 mm, the processing speed was 1.5 m / min, and the shot density was 37 shots / cm ² . During the needle punching, almost no scattering of sodium polyacrylate or bentonite was observed. Then, the needle-punched product is dried to solidify the adhesive, and the water-stopping material of the present invention.
I got (6). The waterproofing material (6) thus obtained had a thickness of about 9 mm, and the bentonite layer (5) had a thickness of about 5 mm.
The cross section was as shown in FIG. In the actual waterproofing material, the boundaries between the layers were not clear as shown in the figure due to the needle punching treatment, but the existence of each layer was clearly recognized.

Comparative Example 1 A water blocking material was produced in the same manner as in Example 1 without using sodium polyacrylate and an adhesive. Since we didn't use any glue here,
Scattering of bentonite was remarkably observed during needle punching. The obtained waterproof material had a thickness of about 8 mm, and the thickness of the bentonite layer was about 5 mm.

The waterproof pressure resistance of the waterproof materials of Example 1 and Comparative Example 1 was measured. Table 1 shows the results.

[0038]

[Table 1]

The waterproof pressure resistance was measured according to the water resistance test method of JIS L 1079, and at the time of measurement, a water pressure gauge for waterproof material and its auxiliary tool were separately used. Moreover, in the table, "at the time of dryness" means that the water blocking agent layer was measured when it was in a dry state. In addition, “30 minutes later” means that after setting the waterproofing material in the tester, contacting it with water pressure of 0.1 kg / cm ² or less, and applying water pressure 30 minutes after contacting with water "
Means that the water-stopping material was set in the tester and brought into contact with water according to the above-mentioned procedure, and the measurement was performed in a state where the bentonite was completely swollen.

The waterproofing material of Example 1 has a higher water pressure resistance when dried than that of Comparative Example 1. This is because the polymer absorber rapidly absorbed a large amount of water and swollen to form a water blocking layer. Further, the water pressure resistance of Example 1 is higher after 30 minutes of contact with water and in the completely swollen state. This is because in the water-stopping material of Example 1, the polymer absorbent swelled remarkably due to water absorption and seals the fiber gaps in the non-woven fabric, so that the bentonite is prevented from passing through, resulting in improved water pressure resistance. it is conceivable that. On the other hand, in the water-stopping material of Comparative Example 1, since the “sealing layer” between the non-woven fabric and the bentonite does not exist, the bentonite easily flows out of the water-stopping material. Therefore, its water pressure resistance is low.

[0041]

As described above, according to the present invention, a water absorbing substance having a high water absorbing rate such as a polymer absorber is laminated on at least one surface of a water absorbing substance having a low water absorbing rate such as bentonite. It is characterized in that the water blocking agent layer is constituted by. Therefore, even when a large amount of water suddenly flows in, a considerable amount of water is quickly absorbed in the polymer absorbent, so that the flow of the bentonite layer is suppressed and water channels are not formed. Then, after the polymer absorber becomes saturated at a relatively early stage, the bentonite gradually absorbs water and swells, so that the water blocking material as a whole exhibits a water blocking effect for a long period of time. In addition, the polymer absorbent body after absorbing water remarkably increases in volume to form a kind of sealing layer, and also plays a role of preventing bentonite from flowing out of the water blocking material.

Further, in the method for producing a waterproofing material of the present invention, a part of the layers is bonded by using an adhesive, and needle punching is performed while the adhesive is in a wet state to integrate the whole. However, according to such a method, excessive scattering of the waterproofing agent during the production and construction of the waterproofing material is suppressed, so that the working environment is greatly improved.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for producing a water blocking material according to the present invention.

FIG. 2 is a cross-sectional view showing an example of the water blocking material of the present invention.

[Explanation of symbols]

 1A, 1B Water-permeable sheet 2A, 2B Polymeric absorber 3A, 3B Composite sheet 4 Reinforcing sheet 5 Bentonite 6 Water stop material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area E02B 3/12 E02B 3/12 7/02 7/02 A E02D 31/02 E02D 31/02 E21D 11 / 38 E21D 11/38 A

Claims (4)

[Claims] 1. A water-permeable sheet on both sides of a waterproofing agent layer, which is formed by laminating two or more water-absorbing substances having different water-absorption rates so that the water-absorbing substance having the highest water-absorption rate is located on at least one surface. A water blocking material with a coating material made of. 2. The water blocking agent layer is formed by laminating a water absorbent substance made of an inorganic substance and a polymer absorbent so that the polymer absorbent is located on at least one surface. Water stop material described 3. An adhesive is interposed between each layer of water-absorbing substances constituting the water-stopping agent layer or between a part of the layers and / or between the water-stopping agent layer and the covering material. The water blocking material according to claim 1 or 2, wherein the water blocking agent layer and the covering material are joined by needle punching. 4. A composite sheet in which a polymer absorbent is laminated and fixed on one surface of a water-permeable sheet with an adhesive on one surface of a water-absorbent material layer made of an inorganic material, with the water-permeable sheet facing outside. However, the other surface is a water-permeable sheet alone, or the composite sheet is laminated so that the water-permeable sheet is on the outside, and a needle punching treatment is applied to this before the adhesive in the composite sheet solidifies. And a method of manufacturing a waterproof material.