JPH04128410A - Water impervious sheet - Google Patents

Abstract

PURPOSE:To obtain a water impervious sheet which can be manufactured at any desired thickness by coating high water absorbing inorganic particles having a predetermined particle diameter to the water permeable sheet having a predetermined strength with the specified adhesive showing the elasticity at an ordinary temperature, and forming a sheet as a plurality of layers which consists of multiple sheets coated with the high water absorbing inorganic particles. CONSTITUTION:High water absorbing inorganic particles 2 are distributed between an upper and a lower water permeable sheets 1, and the adhesive 3 is distributed fibrously between layers of the inorganic particles 2 to form a water impervious sheet. The hot-melt adhesive 3 is sprayed like a spider's net on the permeable polyester non woven fabric 1 having a tensile strength at about 30kg/5cm width, and thereafter, bentonite granulated products, which has a particle diameter of about 1.5mm and a length of about 2.5mm and shows the elasticity at an ordinary temperature, are stuck immediately at a predetermined thickness. This process is repeated sometimes to laminate the permeable polyester non woven fabric, and they are rolled by a pressurizing roller to form a water impervious sheet having a thickness of about 15mm. A permanent water impervious sheet having high reliability and any desired thickness is thereby obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sheet used mainly for water-blocking civil engineering structures, such as lining waterways and lining ponds.

(Prior Art) Conventional water-blocking sheets mainly use polymeric materials such as synthetic rubber and synthetic resin sheets. These polymeric materials are prone to defects such as poor joints and pinholes, and if they are damaged or punctured, water leaks, and it is difficult to expect a permanent water-stopping effect. Therefore, a water-blocking sheet to prevent water leakage is created by gluing and fixing granules of highly water-absorbing and gelling material between water-permeable sheets with a thickness of 1. ．． A sheet of about 5 mm (Japanese Unexamined Patent Publication No. 60-240446) and a waterproof sheet in which particles that can expand upon contact with water are attached to a water-impermeable sheet with an adhesive (Japanese Unexamined Patent Publication No. 63-501413) Publications) etc. are known.

However, in the sheet described in JP-A-60-240446, even if adhesive is present near the water-permeable material, it is not present in the highly water-absorbent or gelled material, so gelled material that can be adhesively fixed is used. amount is limited. The gelling substance is fixed in a single layer, so to speak, and even if you try to obtain a thick product with multiple layers, the gelling substance in the middle layer will move freely within the layers, making the sheet thickness uneven and unsatisfactory. Not only will it not be possible to obtain a water-blocking sheet, but the water-blocking effect itself cannot be expected.

In addition, in order to increase the thickness of the sheet described in this publication, if a common rubber adhesive with adhesive strength and high flexibility described in this publication is present between gelling substances,
Even if the adhesive is sticky and flexible,
The adhesive may harden in a block state, or the adhesive may accumulate near the bottom layer of the gelled material, impeding the movement of the gelled material. As a result, the completed sea I itself becomes rigid and cannot be rolled up or follows the unevenness of the ground during construction, and furthermore, the gelled material peels off and falls off during handling before construction. There are drawbacks such as these, and the water-stopping effect is incomplete.

Further, in the sheet described in JP-A-63-501.413, water-swellable particles such as sodium montmorillonite are adhered to a water-impermeable sheet via an adhesive. However, the adhesion of the adhesive to the particles tends to be uneven, and the adhesive itself becomes rigid at room temperature, so if the amount of particles filled is increased, the flexibility of the finished sheet itself will decrease. The sheet is lost, cannot follow the unevenness of the ground during construction, causes cracks, etc., and has drawbacks such as particles falling off from the sheet, making it impossible to obtain a complete water-stopping effect.

(Problems to be Solved by the Invention) The present invention aims to improve the drawback that when a conventional sheet is made thick, it becomes rigid and a practical sheet can only be obtained with a thin thickness.

(Means for Solving the Problems) The sheet of the present invention is composed of multiple layers of highly water-absorbing inorganic material particles having a particle size of 0.5 to 5.0 mm bound between water-permeable sheets. This is a water-shielding sheet in which an adhesive exhibiting elasticity at room temperature and dispersed in the form of fibers is present between the highly water-absorbing inorganic material particles and between the highly water-absorbing inorganic material particles and the water-permeable sheet.

As shown in FIGS. 1 and 2, the structure of this sheet is that multiple layers of highly water-absorbing inorganic material particles 2 are present between upper and lower water-permeable sheets 1, and each of the super-absorbing inorganic material particles is This is a water-shielding sheet in which an adhesive 3 exhibiting elasticity at room temperature is present in a fibrous form between the particles of the highly water-absorbing inorganic material and the water-permeable sheet.

Examples of water permeable sheets used in the present invention include natural fibers, recycled fibers, inorganic fibers, nylon, polyester,
Examples include woven and knitted fabrics of synthetic fibers such as polypropylene, sheet-like materials such as non-woven fabrics, and paper. Among these, long-fiber nonwoven fabrics of synthetic fibers, knit reinforced nonwoven fabrics, and tape yarn fabrics made of synthetic fibers are particularly suitable as water-permeable sheets in terms of strength, water resistance, and fineness.

The role of the water-permeable sheet used in the present invention is not only to hold the highly water-absorbing inorganic material particles, but also to serve as a support layer that can withstand handling during on-site installation, and to prevent the highly water-absorbing inorganic material from washing away after being laid. be. Therefore, the water-permeable sheet on at least one side has a tensile strength (20 kg 15 cm width or more).
Measuring method: It is preferable to use a method according to JIS L 1096 (Tensile test method for textiles). On the other hand, the sheet on the other surface is preferably a fine nonwoven fabric.

As described above, each water-permeable sheet has a different role, but as long as it satisfies these required performances, non-woven fabrics or woven fabrics can be used in combination as appropriate.

The highly water-absorbing inorganic substance used in the present invention may be anything as long as it absorbs water in the presence of water and can swell with hydration. Examples include clay minerals such as bentonite, montmorillonite, hectorite, saponite, beidellite, acpulgite, and sepiolite. Either pulverized or granulated granules of these highly water-absorbing inorganic substances can be used. The latter is preferred.

In addition, the particle size of the super absorbent inorganic material particles is 0.5 to 5.0 mm.
Use the one. The particle size referred to here is obtained by a method of measuring the size of a general irregular single particle in powder. This is the diameter in a fixed direction as measured using an ordinary microscope, and the numerical value is the minor axis diameter.

Therefore, the particle size of a pulverized product of a super absorbent inorganic substance is expressed by the short axis diameter of the diameter in a fixed direction, and in the case of a granulated product, the short axis diameter of the cross section is taken as the particle size, and the maximum diameter in the direction perpendicular to the cross section is The particle height is expressed as length, and the length of the granulated product used is 0.5 to 5.0 mm. That is, if the particle size of the superabsorbent inorganic substance is less than 0.5 mm, the apparent surface area of the particles increases, making it difficult to evenly and sufficiently fix the particles with an adhesive. Moreover, if it exceeds 5.0 mm, the voids between the particles will increase and even the swollen particles will not be able to completely fill these voids, making it impossible to expect a complete water-stopping effect. Particularly suitable is one of 1.0 to 3.0 m+n.

One feature of the water-blocking sheet of the present invention is that an adhesive exhibiting elasticity at room temperature is present in a fibrous form between the super-absorbent inorganic material particles and between the particles and the water-permeable sheet. . As shown in FIG. 2, this adhesive is also present in the form of fibers and dispersed between the layers of the super-absorbent inorganic material particles 2, and not only does it adhere the super-absorbent inorganic material particles to each other, but also makes it difficult to peel them off. Then, it shows stringiness.

In order for the adhesive to be dispersed in the form of fibers and exhibit elasticity at room temperature, the adhesive must first be made of styrene-butadiene-styrene (SBS), styrene-isobutylene-styrene (SIS), etc. Styrenic block copolymers, polyester-based and polyurethane-based elastomers, and synthetic rubber-based polymers such as chloroprene rubber and nitrile rubber, with tackifiers such as rosin, softeners such as process oil, and other additives if necessary. Add the agent,
An adhesive with hot melt properties is used,
By hot-melting this adhesive and spraying it in the form of spider threads, it exhibits elasticity even at room temperature and exists in a fibrously dispersed state.

Here, as a method for dispersing the adhesive in the form of fibers,
For example, spray coating, spiral coating, or the like may be used. In order to disperse the hot-melt adhesive into fibers and spray apply it, air pressure (for example 1.5
The softened adhesive (approximately 2.5 kg 1 crl) is pumped, and a plurality of small holes with a diameter of 1 to 1.5 mmΦ are formed, for example, 4
The most preferable method is to blow it out from separate nozzles.

The water-shielding sheet of the present invention that satisfies all of these requirements can have excellent flexibility even if it has a dry thickness of 3 to 20 mm, as shown by d in FIG.

The thickness of the water-blocking sheet of the present invention is preferably 3 to 20 mm. If the thickness is less than 3 mm, the amount of superabsorbent inorganic material particles used will be less than 5 kg/m, making it difficult to obtain a permanent water-blocking effect. Due to the accompanying construction time and effort, it is difficult to obtain a satisfactory water-blocking sheet.Especially, 10~
A diameter of 15 mm is suitable.

Next, a method for manufacturing the water-blocking sheet of the present invention will be described. The method for producing the water-blocking sheet of the present invention uses a fabric with excellent water permeability and strength, such as a non-woven fabric or a woven or knitted fabric made of synthetic fibers such as polyester or polypropylene polymer, and on top of this, for example, The elastomeric hotmel type I adhesive is heated to a high temperature, softened, and sprayed in the form of fibers. Immediately, the highly water-absorbent inorganic material particles are placed on the fabric to which the adhesive has been applied, and after a predetermined amount of particles are adhered thereto, the adhesive is applied again in the same manner. This operation is repeated several times to form multiple layers of the inorganic snow grains, and then the adhesive is sprayed again and the flexible non-woven fabric is layered and rolled and crimped. There are ways to do this.

EXAMPLES The present invention will be explained below using Examples, but the present invention is not limited thereto in any way.

(Example) Example 1 Tensile strength 30kg15cmrlt (JIS L-10
96 method, a water permeable polyester non-woven fabric (manufactured by Asahi Kasei Industries, Ltd.) having a vertical dimension, an elastomer such as a styrene-butadiene block copolymer, a tackifier such as rosin, a softener such as process oil, etc. Hot melt adhesive containing anti-aging agents and fillers is heated to 25°C in advance.
Use a nozzle with 4 holes with a diameter of 1.2 mm to spray it in the form of a spider thread after it has been softened.
kg/cnf), a bentonite granulated product with a particle size of 1.5 mm and a length of 2.5 mm is immediately introduced and deposited in a predetermined amount. Spray adhesive again on the bentonite granules that have adhered to the soil.

After repeating this operation several times, a water-permeable polyester nonwoven fabric (manufactured by Asahi Kasei Kogyo Co., Ltd., basis weight: 20 g/m) was layered and integrated through a pressure roll to obtain a water-blocking sheet with a thickness of 15 mm.

Table 1 shows the results of examining the performance of the obtained water-blocking sheet.

The water barrier coefficient of this sheet was on the order of 10-9, and an impermeable layer was formed. Moreover, this sheet had excellent flexibility and could be easily wound into a roll with a diameter of 20 cm. Furthermore, when I tried to peel off the nonwoven fabric portion of the obtained sheet, the adhesive became stringy.

Example 2 The same adhesive used in Example 1 was spray-coated onto a water-permeable polypropylene tape yarn fabric having a tensile strength of 25 kg and a width of 15 cm (as measured by JIS L-1096 method), and immediately a woven fabric with a particle size of 1.2 mm was applied. Add the crushed bentonite product and allow it to adhere to the specified amount. This repeated operation was performed in the same manner as in Example 1, and finally a water-permeable polypropylene nonwoven fabric (manufactured by Asahi Kasei Corporation, basis weight 20g/
rn') were stacked and integrated through a pressure roll to obtain a water-shielding sheet with a thickness of 6 mm.

Table 1 shows the results of examining the performance of the obtained water-blocking sheet.

The obtained sheet showed sufficient water-stopping effect and excellent flexibility.

Example 3 The particle size of the bentonite granulated product was 2.8 mm and the length was 3.0 mm.
A water-shielding sheet was obtained under the same conditions as in Example 1, except that the water-shielding sheet was replaced with one of mm. Table 1 shows the results of examining the performance of the obtained water-blocking sheet. The obtained sheet showed sufficient water-stopping effect and excellent flexibility.

Example 4 The particle size of the bentonite granulated product was 0.7 mm and the length was 1.2 mm.
A water-shielding sheet was obtained under the same conditions as in Example 1, except that the water-shielding sheet was replaced with one of mm. Table 1 shows the results of examining the performance of the obtained water-blocking sheet. The obtained sheet showed sufficient water-stopping effect and excellent flexibility.

Example 5 The particle size of the bentonite granulated product was 3.5 mm and the length was 4.5 mm.
A water-shielding sheet was obtained under the same conditions as in Example 1, except that the water-shielding sheet was replaced with one of mm. Table 1 shows the results of examining the performance of the obtained water-blocking sheet. The obtained sheet showed sufficient water-stopping effect and excellent flexibility.

Comparative Example 1 A water-blocking sheet was obtained under the same conditions as in Example 1, except that the bentonite particle size was 0.4 mm and the length was 0.4 mm. Table 1 shows the results of examining the performance of the obtained water-blocking sheet. The obtained sheet had uneven thickness, and a sufficient water-stopping effect could not be obtained.

Comparative Example 2 A water-blocking sheet was obtained under the same conditions as in Example 1, except that only the adhesive was replaced with a vinyl acetate resin type adhesive (solvent type).

Table 1 shows the results of examining the performance of the obtained water-blocking sheet.

The obtained sheet had no flexibility at all and had poor formability.

(Margin below) table In addition, The performance tests in the table are Run as below. It was.

■ Formability - The water-blocking sheet was cut using a cutter knife, etc., and the condition of the cut end was observed. If particles such as bentonite inside were spilled from the cut end, it was considered to be defective.

Permeability coefficient: Pressure filtration tester (cell: 100 mm)
A water permeability test was carried out by filling the sample with water at a constant pressure of 1 kg/cnf to determine the water permeability coefficient.

(Effects of the Invention) According to the present invention, by dispersing a specific adhesive that exhibits elasticity at room temperature in the form of fibers and making it exist between particles of a highly water-absorbing inorganic material having a specific particle size range and length, The water-absorbing inorganic material particles are restrained in a predetermined position between the water-permeable sheets, making the thickness uniform. ■ The thickness of the sheet itself can be adjusted as desired. ■ The sheet has excellent flexibility and can be rolled into a roll at the construction site. ■The highly water-absorbent inorganic material particles become powdered and do not fall off.Furthermore, ■If the thickness d is increased, after the highly water-absorbent inorganic material swells when it comes into contact with water, it can be transported to rocks, etc. Because of the sharp edges of the material, even if a hole is created that penetrates the nuclear layer, it has an excellent self-healing effect that closes the hole within a short time, making it a reliable and permanent stopper. It is possible to provide a water-blocking sheet that can be expected to have a water effect.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of one embodiment of the water-shielding sheet of the present invention, and FIG. 2 is a partially enlarged view of the highly water-absorbent inorganic material branch with adhesive applied to it, viewed from above. be. The symbols in the figure are as follows. 1... Water permeable sheet 2... Highly absorbent inorganic material particles 3... Adhesive d... Thickness of multiple layers of highly water absorbent inorganic material particles Patent applicant Asahi Kasei Corporation J r

Claims (1)

[Claims] 1. Multiple layers of highly water-absorbent inorganic material particles having a particle size of 0.5 to 5.0 mm are bound between water-permeable sheets, and between the particles of the super-absorbent inorganic material particles and the super-absorbent inorganic material particles. A water-shielding sheet characterized by the presence of an adhesive that exhibits elasticity at room temperature and is dispersed in the form of fibers between the water-permeable sheet and the water-permeable sheet.