JP5737862B2 - Capping sheet joining method and joining structure - Google Patents

Description

  The present invention relates to a capping sheet joining method used in a waste disposal site and the like, and a capping sheet joining structure obtained by the joining method.

  In waste disposal sites and illegal dumping sites, water-impervious sheets and moisture-permeable waterproof sheets that do not allow water to pass through are used as capping sheets for the purpose of preventing the penetration of rainwater and the like. Among these, as the capping sheet, a moisture-permeable waterproof sheet that blocks the penetration of rainwater and permeates various gases and water vapor generated from waste is preferably used.

  As a structure of a capping sheet, for example, a structure in which a nonwoven fabric obtained by a needle punch method or the like is laminated on both surfaces of a moisture permeable waterproof film is known (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). ). Such a capping sheet is usually used by using a plurality of sheets and joining the edges of adjacent sheets laid together by adhesive tape or heat fusion.

  In the structure of the capping sheet, the nonwoven fabric is excellent in cushioning properties, so that it does not damage the moisture permeable waterproof film and does not impair the performance of the moisture permeable waterproof film, and is therefore used as an ideal reinforcing material. The needle punched nonwoven fabric has a certain thickness and has many voids. For this reason, when the edges of the capping sheet are joined and used, the embankment placed on the capping sheet contains rainwater after the rain. After that, if the embankment containing rainwater remains on the sheet for a long time, water pressure is applied to the capping sheet, and water leaks from the gaps in the needle punched nonwoven fabric at the joint, and rainwater penetrates inside. I had to do it. That is, rainwater does not permeate in a short period, but if rainwater stays for a long time, it is difficult to prevent rainwater from permeating from the joint.

  As a method for evaluating the water-imperviousness (resistance to penetration of rainwater at the joint) of the capping sheet joint, in the above-mentioned prior art document, the water pressure measurement obtained by the water resistance test A method of JIS L 1092 is used. It has been. This water resistance indicates the water pressure at the time of water leakage when “the water pressure applied to the sample is increased at a constant speed”, and “when a constant water pressure is continuously applied to the sample for a predetermined time or longer (actual It does not observe the presence or absence of water leakage in the case of the same measurement as in use). In other words, the method is based on the idea that even if a water pressure lower than the water pressure resistance is applied, no water leakage occurs at the joint, and is not based on actual use. For example, when it has a 50 cm water head (water pressure resistance of about 5 kPa), even if a water pressure of less than 50 cm water head is applied to the upper surface of the capping sheet, water leakage does not occur.

  Therefore, at the joint portion of the capping sheet, a water pressure smaller than the water pressure value obtained in the water resistance test was continuously added, and the “water resistance evaluation” as referred to in this specification was performed. As time passed, water leakage was confirmed. That is, in the nonwoven fabric, the shape of the void formed by the fiber is complicated, and it takes a certain amount of time for the fiber surface to be completely wetted by water permeation, so no water leakage is confirmed in a short water resistance test. However, in the case of long-time measurement, water leakage is confirmed.

  The method for measuring water resistance in the above prior art documents is suitable for evaluating the penetration of rainwater in a short time, but is not suitable for evaluating the penetration of rainwater staying for a long time. This is because the measurement of the water pressure resistance is performed in a relatively short time of several minutes to several tens of minutes, and the measurement is completed when water penetration is recognized. This is because of the evaluation.

  In addition, in the water resistance test in the above-mentioned prior art document, once the water permeation path is formed in the fiber, the apparent water permeation resistance is reduced and the water permeation coefficient is increased, whereby the water resistance obtained in the water resistance test is obtained. There arises a problem that the magnitude relationship between the water pressure and the water permeability coefficient obtained by the water permeability evaluation does not necessarily match.

  Therefore, it is not sufficient to use the conventional “water pressure resistance” as an index to evaluate the water-imperviousness at the joint of the capping sheet.

  Therefore, the present inventors evaluated the situation close to the actual infiltration of rainwater by measuring the amount of water permeation after the elapse of a certain time. The method for evaluating the amount of water permeation after the elapse of a certain time proposed by the present inventors is to measure the amount of water permeation from the joint after elapse of 10,000 seconds or more using the apparatus of FIG. is there. When measured by such an evaluation method, it is difficult to sufficiently suppress or prevent the penetration of rainwater into the joint by the simple adhesion described in the prior art document.

Japanese Patent No. 4377636 JP 2006-116512 A JP 2009-183878 A

  The present invention relates to a capping sheet joining method capable of preventing rainwater from permeating from a joined part even after a long stay even when a needle punched nonwoven fabric having excellent cushioning properties is used, and a capping obtained by the method It aims at providing the joining structure of a sheet | seat.

  As a result of intensive studies to solve the above problems, the present inventors first filled the void of the nonwoven fabric constituting the capping sheet in the portion where the edges of the capping sheet were overlapped, and then the edge of the edge. The present inventors have found that the above-mentioned problems can be solved by joining, and have reached the present invention.

That is, the gist of the present invention is as follows.
(1) When overlapping and joining the edges of a pair of capping sheets in which a nonwoven fabric layer is laminated on a moisture permeable waterproof film,
(A) compressing the portion to be the joint portion of the capping sheet , or (b) interposing an adhesive layer made of a fluid material between the edges of the overlapped capping sheets, By causing the edge of the adhesive layer to protrude from the edge of the capping sheet and allowing the fluid substance to enter the nonwoven fabric layer of the capping sheet ,
After filling the voids in the nonwoven layer,
By joining,
When the water pressure of 50 g weight / cm ² is applied to the joint portion of the obtained capping sheet, the water permeability coefficient k calculated using the following formula is 1 × 10 ⁻⁶ cm / second or less. A capping sheet joining method characterized by the above.
k = (d / h) × [V / (A × t)]
{D: Sample thickness (cm)
The thickness d of the sample is set to be twice the thickness of the material of the base material portion.
h: Head of water (cm)
V: Water permeability (cm ³ )
t: Water permeability measurement time (seconds)
The water permeability measurement time is 10,000 seconds or longer.
A: Sample area (cm ² )
The sample area is the area of the water contact surface and is calculated by the following formula.
(Area of water contact surface) = π × [30 (cm) / 2] ² }
(2) The method for joining a capping sheet according to (1), wherein compressing a portion to be a joined portion in (a) is filling a gap in the nonwoven fabric layer by a hot roll press .
(3) In (b), an adhesive layer composed of a fluid material is interposed between the edges of the overlapped capping sheets, and the edges of the adhesive layer are separated from the edges of the capping sheet. When the material having fluidity is allowed to enter the inside of the non-woven fabric layer of the capping sheet, as the material having fluidity, an acrylic adhesive, a butyl rubber adhesive, a urethane adhesive, an asphalt adhesive, (1) The capping sheet joining method according to (1), wherein at least one selected from modified asphalt pressure-sensitive adhesives is used.
(4) A joining structure in which the edges of the capping sheet in which the nonwoven fabric layer is formed on both surfaces of the moisture permeable waterproof film are joined together,
The adhesive layer made of a material having fluidity is interposed between the edges of the capping sheets that have been compressed, or between the edges of the overlapped capping sheets, and the end of the adhesive layer The edge protrudes from the edge of the capping sheet, and the substance having the fluidity enters the inside of the nonwoven fabric layer of the capping sheet, so that the void of the nonwoven fabric layer is filled,
A joining structure of a capping sheet, wherein a water permeability coefficient k calculated by the following formula when a water pressure of 50 g weight / cm ² is applied is 1 × 10 ⁻⁶ cm / second or less .
k = (d / h) × [V / (A × t)]
{D: Sample thickness (cm)
The thickness d of the sample is set to be twice the thickness of the material of the base material portion.
h: Head of water (cm)
V: Water permeability (cm ³ )
t: Water permeability measurement time (seconds)
The water permeability measurement time is 10,000 seconds or longer.
A: Sample area (cm ² )
The sample area is the area of the water contact surface and is calculated by the following formula.
(Area of water contact surface) = π × [30 (cm) / 2] ² }
(5) The material having fluidity is at least one selected from an acrylic adhesive, a butyl rubber adhesive, a urethane adhesive, an asphalt adhesive, and a modified asphalt adhesive. (4) Capping sheet joining structure.

  According to the present invention, there is provided a method for joining a capping sheet that can effectively prevent or suppress the penetration of rainwater due to a long-term stay in a joining portion even when a needle punched nonwoven fabric having cushioning properties is used. can do. Furthermore, the joining structure of the capping sheet of the present invention obtained by the joining method can effectively prevent the penetration of rainwater due to a long-term stay.

It is a schematic sectional drawing which shows an example of the state which laid the capping sheet in the waste disposal site. It is a schematic sectional drawing which shows the capping sheet used for this invention. It is the schematic which shows the junction part of the capping sheets in FIG. It is a schematic sectional drawing which shows the junction part of the capping sheet which filled the space | gap of the nonwoven fabric layer by compression. It is a schematic sectional drawing which shows the junction part of the capping sheet which filled the space | gap of the nonwoven fabric layer by interposing the adhesion layer obtained from the substance which has fluidity | liquidity. It is a schematic sectional drawing which shows the joined part of the capping sheet which filled the space | gap of the nonwoven fabric layer by interposing the adhesion layer obtained from the substance which has fluidity, and also coat | covered another adhesion layer from it. It is a schematic sectional drawing which shows the apparatus used for water permeability evaluation. It is the schematic which shows sectional drawing and the top view of the water-contact surface of the sample at the time of water permeability evaluation.

  Hereinafter, the present invention will be described in detail. First, the capping sheet used for the joining method of the capping sheet of this invention is demonstrated.

  FIG. 1 is an example of a cross-sectional structure of a waste disposal site where a capping sheet is used. Here, 1 is earth and sand, for example, the processing pond 2 is formed by digging up this earth and sand from the ground surface. The waste 3a thrown into the treatment pond 2 becomes the upper limit of the allowable amount, and when the treatment pond 2 is closed, the capping sheet 4 is covered to seal the treatment pond 2 in which the waste 3a is accumulated. Further, the embankment 3b is placed on the capping sheet 4 so as to have a height of about 50 cm, for example.

  The structure of this capping sheet 4 is shown in FIG. The capping sheet 4 is obtained by laminating a nonwoven fabric layer 6 formed of a needle punched nonwoven fabric having cushioning properties on both surfaces of a moisture permeable waterproof film 5. That is, the configuration of (nonwoven fabric layer) / (moisture permeable waterproof film) / (nonwoven fabric layer) is adopted.

  Since the nonwoven fabric layer is excellent in cushioning properties, it can prevent damage to the moisture permeable waterproof film 5 in the capping sheet, and additionally plays a role of reinforcing the moisture permeable waterproof film 5. The fiber constituting the nonwoven fabric layer 6 is not particularly limited, but is a fiber obtained from a polymer such as a polyester such as polyethylene terephthalate or polybutylene terephthalate, a polyolefin such as polyethylene or polypropylene, or a polyamide such as nylon 6 or nylon 66. Is mentioned.

  Especially, the fiber which comprises the nonwoven fabric layer 6 employ | adopts the method of compressing the part used as the below-mentioned joining part, and when joining sheets after that, from a viewpoint of the heat adhesiveness of sheets, a core component The sheath component is preferably a core-sheath composite fiber having a melting point different from that of the sheath component, and the sheath component having a lower melting point. As a preferable combination of the core component and the sheath component, there may be mentioned those in which the core component is polyester, for example, polyethylene terephthalate, and the sheath component is polyethylene. With such a combination, the difference in melting point between the core component and the sheath component can be set to 100 ° C. or more, for example. In addition, since the core component polyethylene terephthalate has a high strength among polymers, the core component does not melt even if the sheath component as a heat-adhesive component is sufficiently melted. The form can be reliably maintained.

  The nonwoven fabric constituting the nonwoven fabric layer may be composed of one type of fiber, or may be mixed with other core-sheath composite fibers, single-phase fibers, or other fibers having different cross-sectional shapes. Good. The ratio of the mixed fiber is not particularly limited.

  The fibers constituting the nonwoven fabric layer may be continuous fibers or short fibers. In the case of short fibers, the fiber length is preferably 30 to 150 mm. Moreover, it is preferable that the fineness is 2 to 10 dtex.

  The nonwoven fabric layer is preferably obtained by a needle punch method from the viewpoint of cushioning properties. The nonwoven fabric layer may be further subjected to resin bonding or heat bonding processing as necessary.

Woven cloth layer is not particularly limited, from the viewpoint of preventing damage to the moisture-permeable waterproof film, it is preferable that at least one side is 100 to 1000 g / ^{m 2,} and more preferably 200-500 g / ^{m 2} .

  The thickness of the nonwoven fabric layer is not particularly limited, but from the viewpoint of preventing damage to the moisture-permeable and waterproof film, at least one side is preferably 1000 to 10000 μm, and more preferably 1500 to 6000 μm.

The moisture permeable waterproof film used for the capping sheet 4 is a film having air permeability and water shielding properties, and is made of a polyolefin resin such as polyethylene or polypropylene, polytetrafluoroethylene, or polyvinylidene fluoride. The moisture permeable waterproof film preferably has a moisture permeability in the range of 1000 to 10,000 g / m ² · 24 hr. Those outside this range may have insufficient waterproof performance to prevent rainwater from penetrating into the disposal site, or may obstruct the escape of gas generated inside the disposal site.

  The lamination method of the nonwoven fabric and the moisture permeable waterproof film is not particularly limited, and examples thereof include a method using thermal lamination and a method of bonding using a resin such as a hot melt resin. When employing a heat laminate, it is preferable to appropriately select the conditions under which the moisture-permeable and waterproof film does not melt. Moreover, when employ | adopting adhesion | attachment by resin, it is preferable to select the conditions which do not cover the moisture-permeable waterproof film whole surface with resin.

  Since the treatment pond 2 is very large, the capping sheet 4 is usually laid by joining a plurality of sheets. The configuration of the joint portion where the adjacent capping sheets are joined together can be, for example, as shown in FIG. That is, the edges of adjacent capping sheets can be overlapped with each other, and the overlapping portion 7 can be thermally bonded to form the thermal bonding portion 8, or the two can be joined by tape bonding. it can.

  However, in the prior art, since there are a large number of voids in the nonwoven fabric layer 6, it was not possible to prevent the penetration of rainwater from the voids at the joint when rainwater stayed for a long time. Therefore, it has been difficult to prevent or suppress water permeation when rainwater stays for a long time at the joint. In the present invention, at the portion to be overlapped, after filling the voids of the nonwoven fabric, the edges are overlapped and thermally bonded by melting part or all of the overlapped portion, or tape bonded Join with. Thus, by joining after filling the voids of the nonwoven fabric, it is possible to prevent or suppress permeation of rainwater or the like in the joint for a long period of time.

In the present invention, the following method (a) or (b) is used as a method for filling the voids of the nonwoven fabric.
(A) In the overlapping portion, the capping sheet is compressed in order to compress the nonwoven fabric.
(B) In the overlapping portion, a material having fluidity is allowed to enter the nonwoven fabric.

The above (a) will be described.
In (a), after compressing the part used as the superposition | stacking part 7 so that it may become the structure shown by FIG. 4, it joins. Since the compression is applied, the voids of the nonwoven fabric 6 are crushed and filled, and it is possible to effectively prevent or suppress the penetration of rainwater from the voids for a long period of time at the joint.

  The thickness of the capping sheet after compression is preferably 50% or less of the original thickness from the viewpoint of filling the gap and preventing the penetration of rainwater, and reducing the porosity of the nonwoven fabric based on the reduction in thickness. Is preferably achieved. In the present invention, the porosity of the nonwoven fabric when the thickness is compressed to 50% or less is preferably 80% or less.

The porosity of a nonwoven fabric here shall be the calculated value by the following formula.
a: Nonwoven fabric thickness (cm)
b: Unit area weight of the nonwoven fabric (g / m ² )
c: Density of non-woven resin (g / cm ³ )
Porosity (%) = [a × 100 × 100 × c−b] / (a × 100 × 100 × c) × 100

  The method for compressing the joint portion is not particularly limited, but a method using a hot roll press is preferable from the viewpoint of preventing the moisture-permeable waterproof film from being damaged. Although the conditions of a hot roll press are not specifically limited, For example, it is preferable that they are the temperature of 130-210 degreeC, and the roll speed of 1-30 m / min.

  The above (b) will be described. As shown in FIG. 5, an adhesive layer 9 obtained from a material having fluidity (hereinafter sometimes simply referred to as “adhesive layer”) is used in the portion that becomes the overlapping portion 7. The overlapping portion of the capping sheet is attached with the adhesive layer 9. By doing in this way, the substance which has fluidity at normal temperature can fill the voids of the nonwoven fabric from the adhesive layer, and effectively prevent or suppress the penetration of rainwater from the voids even when the rainwater stays for a long time. can do.

  Examples of the material having fluidity include acrylic adhesives, butyl rubber adhesives, urethane adhesives, asphalt adhesives, and modified asphalt adhesives. Especially, it is preferable that it is a butyl rubber-type adhesive from a durable viewpoint.

  In the case of (b) above, as shown in FIG. 5, the adhesive layer 9 preferably has a portion 9a exposed to the air. By adopting such a configuration, there is an advantage that the adhesive easily penetrates into the capping sheet joining section. It is preferable that the part exposed in the air shall be 3-10 cm from a viewpoint of improving the completeness of filling.

  In addition, as shown in FIG. 6, it is more possible to cover the edge by further attaching another adhesive layer 10 on the joining portion of the two capping sheets attached by the adhesive layer 9. preferable. By joining in this way, it can prevent that a space | gap generate | occur | produces because two adhesion layers contact in a junction part, and can prevent rain water from entering effectively. In addition, the adhesion layer 10 is obtained from the substance which has the fluidity | liquidity mentioned above.

  The thickness of the adhesive layer is preferably 0.1 to 2 mm, and more preferably 0.5 to 2 mm. When the thickness is less than 0.1 mm, it may be difficult to fill the fiber gap with the adhesive component. On the other hand, if it exceeds 2 mm, the strength between the adhesive layers may be insufficient.

  When the method (a) is adopted, the edges of the capping sheet filled with the gap are overlapped, and at least a part of the overlapped portion is thermally bonded or tape-bonded by a known and conventional method to obtain a plurality of The capping sheet can be integrated. The width of the overlapping portion is not particularly limited, but is preferably 10 to 30 cm from the viewpoint of ease of heat fusion work. When the method (b) is adopted, the pressure-sensitive adhesive layer 9 fulfills the function of adhering the capping sheets at the same time as filling the voids of the nonwoven fabric.

  The method for thermal bonding is not particularly limited, and examples thereof include a method using a hot air trowel type and a self-propelled fusion apparatus using a thermal trowel type. The heat bonding conditions are not particularly limited, and can be set to a machine setting temperature of 320 ° C., a machine setting speed of 2 m / min, or the like. Although the width | variety of a heat bonding part is not specifically limited, From a viewpoint of the ease of heat sealing | fusion operation | work, it is preferable that it is about 5 cm.

The joining portion of the capping sheet obtained by the method as described above preferably has a water permeability coefficient of 1 × 10 ⁻⁶ cm / second or less when a water pressure of 50 g weight / cm ² is applied to the joining surface. It is more preferably 10 × ^{8 −8} cm / second or less, and particularly preferably 1 × 10 ⁻¹² cm / second or less. In addition, how to obtain | require a water permeability coefficient is explained in full detail in an Example.

  According to the capping sheet joining method of the present invention, it is possible to join the capping sheet by effectively preventing water permeation from the joining portion even during a long-term stay of rainwater. Moreover, according to the joining structure of the present invention obtained by the joining method, it is possible to effectively prevent water permeation from the joining portion even when rainwater stays for a long time.

  Hereinafter, the present invention will be described more specifically with reference to examples. The method used for water permeability evaluation of an Example and a comparative example is as follows.

(Water pressure resistance evaluation)
According to JIS L-1092 water resistance test method A (low water pressure method), the water pressure resistance was measured using a water resistance tester (“WP-5k” manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.). A sample was placed in a water resistance tester so that the joint portion of the capping sheet passed through the center of the circle, and the water pressure when water droplet leakage was visually confirmed at the joint portion was measured, and this was taken as the water pressure resistance. Since the capping sheet is laid in the soil and used in a situation where deformation in the in-plane direction is restricted, a stainless steel mesh is placed on the top surface of the sample to prevent deformation (expansion) of the sample due to water pressure. Measurements were performed.

(Permeability evaluation)
Using the water permeability evaluation apparatus shown in FIG. 7, the water permeability V (cm ³ ) from the joint at a fixed time t (second) was measured under the following conditions. As shown in FIG. 7, a plurality of holes 20 are arranged in the bottom plate 12 arranged on the lower surface of the sample 11. The water that has passed through the hole 20 accumulates in the tray 13 for measuring the amount of water permeation. The amount of water accumulated in the tray 13 was measured, and this was taken as the water permeability V from the joined portion of the capping sheet.
The water contact surface diameter 15 of the sample was 30 cm, and the water head 16 was 50 cm.
Moreover, in water permeability evaluation, the sample was arrange | positioned so that the junction part 17 of a capping sheet may pass the center of a circle, as shown in FIG.

From the above measurement results, the hydraulic conductivity k (cm / sec) was calculated using the following formula.
k = (d / h) × [V / (A × t)]
d: Sample thickness (cm)
Note that the thickness d of the sample was twice the thickness of the material of the base material portion (that is, two sheets).
h: Head of water (cm)
V: Water permeability (cm ³ )
t: Water permeability measurement time (seconds)
The water permeability measurement time was set to 10,000 seconds or longer.
A: Sample area (cm ² )
The sample area is the area of the water contact surface and was calculated by the following formula.
(Area of water contact surface) = π × [30 (cm) / 2] ²

Example 1
The core part is polyethylene terephthalate (PET) having a melting point of 260 ° C., the sheath part is polyethylene (PE) having a melting point of 125 ° C., and the mixing ratio of the core part and the sheath part is a volume ratio of (core part): (sheath part) ) = 50: 50, core / sheath portion = PET / PE core-sheath composite fiber was obtained. Using this fiber, a spunbonded nonwoven fabric having a constituent fiber fineness of 5 dtex and a basis weight of 100 g / m ² was prepared.

Three spunbond nonwoven fabrics having a basis weight of 100 g / m ² were stacked and subjected to needle punching. The needle punching conditions were a punch count of 50 p / cm ² and a needle depth of 10 mm. Thus, a needle punched nonwoven fabric having a cushioning property of 3 mm in thickness was obtained.

  Next, a laminate having a configuration of (needle punch nonwoven fabric) / (moisture permeable waterproof film) / (needle punch nonwoven fabric) using the obtained needle punch nonwoven fabric and a polyethylene moisture permeable waterproof film (thickness 100 μm). And a capping sheet was obtained. Lamination of the nonwoven fabric and the moisture permeable waterproof film was performed by an adhesive process using hot melt. Next, pressing with a hot roll was performed at both ends 20 cm in the width direction of the capping sheet to compress the voids in the nonwoven fabric layer, and the thickness of the portions at the ends 20 cm was set to 2 mm. The conditions of the hot roll were a temperature of 180 ° C. and a speed of 2 m / min.

  Using two capping sheets obtained by heat-compressing the edges obtained as described above, the edges are overlapped so that the overlapped width is 10 cm, and a self-propelled thermal fusion apparatus (manufactured by Leister, Using the product name “TWINNY”), the edges were heat-sealed together at a machine setting temperature of 320 ° C. and a machine setting speed of 2 m / min to obtain a joint. When the water permeability was evaluated at the joint, water permeability was not confirmed even after 24 hours. Moreover, it was 13.8 kPa when the water-proof pressure of this junction part was measured.

(Example 2)
A black spunbond nonwoven fabric (hereinafter sometimes referred to as “nonwoven fabric A”) composed of polyethylene terephthalate formed by thermally bonding fibers having a width of 2 m, a fineness of constituent fibers of 2.2 dtex, and a basis weight of 130 g / m ² Using a black spunbonded non-woven fabric made of polyethylene terephthalate in which fibers having a width of 2 m, a fineness of constituent fibers of 3.8 dtex, and a basis weight of 300 g / m ² are entangled with each other by a needle punch, a cushioning property having a thickness of 3 mm A certain needle punched nonwoven fabric (hereinafter sometimes referred to as “nonwoven fabric B”) was obtained.

  The nonwoven fabric A, a moisture-permeable waterproof film made of polyethylene (thickness: 100 μm), and the nonwoven fabric B are used to perform hot-melt bonding, and have a configuration of (nonwoven fabric A) / (breathable waterproof film) / (nonwoven fabric B). A laminate was produced to obtain a capping sheet.

  Two pieces of this capping sheet were prepared by cutting to a length of 10 m, and butyl rubber double-sided pressure-sensitive adhesive tape (width: 10 cm, thickness) so that the nonwoven fabric A was on the upper layer side and the overlapped width was 8 cm. 1 mm) (hereinafter may be referred to as “adhesive tape C”) to form a laminated portion of the capping sheets. At this time, the adhesive layer was exposed at a width of 2 cm.

Furthermore, a butyl rubber single-sided pressure-sensitive adhesive tape (width: 20 cm, thickness: 1.5 mm) is bonded to the inside of the nonwoven fabric of the capping sheet by being bonded via the pressure-sensitive adhesive tape C (width: 20 cm, thickness: 1.5 mm) ( Hereinafter, the adhesive surface of the adhesive tape D and the exposed adhesive surface of the adhesive tape C were affixed while pressing so that air was not caught. In the same manner as in Example 1, the edges were thermally fused to obtain a joint. When the water permeability was evaluated at the joint, the water permeability coefficient k was 1.2 × 10 ⁻⁷ cm / s. Moreover, it was 38.2 kPa when the water-proof pressure of this junction part was measured.

(Comparative Example 1)
In the same manner as in Example 1, a capping sheet having a configuration of (needle punch nonwoven fabric) / (moisture permeable waterproof film) / (needle punch nonwoven fabric) was obtained. Two edges of the capping sheet were used, and the edges were heat-sealed in the same manner as in Example 1 except that the edges were not thermally compressed to obtain a joint. When the water permeability was evaluated at the joint, the water permeability coefficient k was 4.2 × 10 ⁻⁴ cm / s. Moreover, it was 10.1 kPa when the water-proof pressure of this junction part was measured.

(Comparative Example 2)
In the same manner as in Example 2, a capping sheet having a configuration of (nonwoven fabric A) / (moisture permeable waterproof film) / (nonwoven fabric B) was obtained. Two edges of the capping sheet were used, and the edges were heat-sealed in the same manner as in Example 1 except that the edges were not thermally compressed to obtain a joint. When the water permeability was evaluated at the joint, the water permeability coefficient k was 1.3 × 10 ⁻⁴ cm / s. Moreover, it was 2.2 kPa when the water-proof pressure of this junction part was measured.

  The evaluation results of Examples 1 and 2 and Comparative Examples 1 and 2 are summarized in Table 1.

  As is clear from the above, the gaps of the nonwoven fabric were filled in the joint portions of the capping sheets obtained in Examples 1 and 2. Therefore, Example 1 can prevent long-term water permeation, and Example 2 can effectively suppress long-term water permeation.

  The capping sheets of Comparative Example 1 and Comparative Example 2 were not able to suppress water permeation for a long period of time because the edges were joined without performing the process of filling the voids of the nonwoven fabric.

DESCRIPTION OF SYMBOLS 1 Earth and sand 2 Treatment pond 3a Waste 3b Filling 4 Capping sheet 5 Moisture permeable waterproof film 6 Nonwoven fabric layer 7 Lamination | stacking part 8 Thermal bonding part 9 Adhesive layer 9a Exposed part 10 in the air of the adhesive layer 9 Adhesive layer 11 Sample 12 Bottom plate 13 Saucepan 14 Water 15 Diameter of water contact surface of sample 16 Water head 17 Joint 18 Cross section 19 of water contact surface of sample 19 Upper surface 20 of water contact surface of sample

Claims (5)

When overlapping and joining the edges of a pair of capping sheets in which a nonwoven fabric layer is laminated on a moisture permeable waterproof film,
(A) compressing the portion to be the joint portion of the capping sheet , or (b) interposing an adhesive layer made of a fluid material between the edges of the overlapped capping sheets, By causing the edge of the adhesive layer to protrude from the edge of the capping sheet and allowing the fluid substance to enter the nonwoven fabric layer of the capping sheet ,
After filling the voids in the nonwoven layer,
By joining,
When the water pressure of 50 g weight / cm ² is applied to the joint portion of the obtained capping sheet, the water permeability coefficient k calculated using the following formula is 1 × 10 ⁻⁶ cm / second or less. A capping sheet joining method characterized by the above.
k = (d / h) × [V / (A × t)]
{D: Sample thickness (cm)
The thickness d of the sample is set to be twice the thickness of the material of the base material portion.
h: Head of water (cm)
V: Water permeability (cm ³ )
t: Water permeability measurement time (seconds)
The water permeability measurement time is 10,000 seconds or longer.
A: Sample area (cm ² )
The sample area is the area of the water contact surface and is calculated by the following formula.
(Area of water contact surface) = π × [30 (cm) / 2] ² } 2. The capping sheet joining method according to claim 1, wherein compressing the part to be the joining part in (a) is filling the voids of the nonwoven fabric layer with a hot roll press . In (b), an adhesive layer composed of a fluid material is interposed between the edges of the overlapped capping sheets, and the edges of the adhesive layer are protruded from the edges of the capping sheet. When the substance having fluidity enters the nonwoven fabric layer of the capping sheet, as the substance having fluidity, acrylic adhesive, butyl rubber adhesive, urethane adhesive, asphalt adhesive, modified asphalt 2. The capping sheet joining method according to claim 1, wherein at least one selected from an adhesive is used. A joining structure in which the edges of a capping sheet in which a nonwoven fabric layer is formed on both surfaces of a moisture permeable waterproof film are joined together,
The adhesive layer made of a material having fluidity is interposed between the edges of the capping sheets that have been compressed, or between the edges of the overlapped capping sheets, and the end of the adhesive layer The edge protrudes from the edge of the capping sheet, and the substance having the fluidity enters the inside of the nonwoven fabric layer of the capping sheet, so that the void of the nonwoven fabric layer is filled,
A joining structure of a capping sheet, wherein a water permeability coefficient k calculated by the following formula when a water pressure of 50 g weight / cm ² is applied is 1 × 10 ⁻⁶ cm / second or less .
k = (d / h) × [V / (A × t)]
{D: Sample thickness (cm)
The thickness d of the sample is set to be twice the thickness of the material of the base material portion.
h: Head of water (cm)
V: Water permeability (cm ³ )
t: Water permeability measurement time (seconds)
The water permeability measurement time is 10,000 seconds or longer.
A: Sample area (cm ² )
The sample area is the area of the water contact surface and is calculated by the following formula.
( Area of water contact surface) = π × [30 (cm) / 2] ² } Substances having fluidity, acrylic adhesive, rubber-based adhesive, a urethane adhesive, an asphalt-based adhesives, claim, characterized in that at least one selected from modified asphalt-based adhesive 4 The joining structure of the capping sheet described.

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