Soil erosion / weed growth control sheet and manufacturing method thereof

Abstract

To provide a soil erosion / weed growth control sheet protecting aesthetic appearance of a slope face, etc., and preventing weed growth and soil collapse due to environmental factors in soil where strong soil is required.SOLUTION: A soil erosion / weed growth control sheet, the weed control sheet formed by bonding a resin sheet without permeability and with elasticity, and a nonwoven fabric sheet together, includes through-holes formed from one surface to the other, at prescribed intervals apart. The control sheet is characterized in that the resin sheet has water proof performance, allowing a small amount of rainwater to flow through the through-holes into the soil side, the nonwoven fabric sheet diffuses the flow-in rainwater through the entire nonwoven fabric sheet by capillary action to supply the lower soil with the rainwater, and the through-holes allow fine particles such as silt and colloids in the soil that flow in with the rainwater, to pass through into the lower soil.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a soil erosion and weed growth inhibition sheet that prevents the growth of weeds on slopes and the like and prevents soil collapse due to environmental factors. [Background technology]

[0002] Traditionally, slopes have been planted with vegetation to prevent erosion by surface runoff from rainwater. However, it takes time for the greening to be complete, and there are cases where the greening base materials, such as plant seeds, are washed away before the slope is fully covered with vegetation. In addition, if weeding is not done periodically after a long period of time has passed, the beauty of the slope will be lost.

[0003] In recent years, instead of vegetation works, slopes have been covered with plastic weed-control sheets. For the weed-control sheets, plastic sheets with high light-blocking properties and no water permeability or nonwoven fabric sheets with a certain degree of water permeability are used.

[0004] On the surface of soil, fine particles such as silt and colloids in the soil usually form soil clumps due to the effect of pore water and maintain their strength, so when covered with a resin sheet that has no water permeability, the soil dries out and the structure of the soil aggregates becomes fragile, causing the soil to lose its strength. If water is supplied to soil that has lost its strength through the gaps at the ends of the resin sheet, the fine particles will melt, forming water channels that will ultimately lead to the collapse of the soil, such as slopes.

[0005] On the other hand, conventional nonwoven weed control sheets have a certain degree of water permeability and have drainage capabilities throughout the entire weed control sheet, so the main body of the weed control sheet retains a fair amount of rainwater due to the capillary phenomenon between the fibers. This allows the rainwater to be supplied to the soil, which helps maintain the strength of the soil. However, the surface of the nonwoven fabric sheet is rough, so plant seeds and soil tend to accumulate on the nonwoven fabric sheet, and the soil underneath the nonwoven fabric sheet also contains moisture, so over time weeds will begin to grow.

[0006] Furthermore, when rainwater is drained from the surface of a nonwoven fabric sheet by utilizing the capillary action of the nonwoven fabric, there is a concern that fine soil particles and silt will also be drained along with the rainwater, causing the fine soil particles and silt to accumulate between the fibers and lead to clogging.

[0007] In order to solve the above problems, the following prior art documents have been disclosed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 6794122 [Patent Document 2] JP 2004-166620 A Summary of the Invention [Problem to be solved by the invention]

[0009] Patent Document 1 discloses a weed control sheet with a water repellent attached to the surface of a nonwoven fabric. The nonwoven fabric contains a water repellent, which can inhibit the evaporation of water from the soil and the associated leaching of nutrients, thereby inhibiting the growth of plants on the weed control sheet. However, the water repellent also inhibits water from penetrating through the surface of the nonwoven fabric, which reduces the strength of the soil.

[0010] Patent Document 2 discloses a conventional weed control sheet 100 in which a resin sheet 110 and a mechanically entangled nonwoven fabric sheet 120 are welded together, and the resin sheet 110 is provided with resin sheet holes 130 at a predetermined density. Fig. 6 shows a cross-sectional view of the conventional weed control sheet 100. Fig. 7 shows an enlarged cross-sectional view of the resin sheet hole 130 of the conventional weed control sheet 100. In the conventional weed control sheet 100, the resin sheet holes 130 are provided, but the holes do not penetrate all the way to the nonwoven fabric sheet 120 and do not communicate with the soil. Moisture WA that flows in from the resin sheet holes 130 diffuses into the nonwoven fabric sheet 120 and is then supplied to the soil.

[0011] However, when the soil base on which a conventional weed-control sheet 100 is installed is strong, mainly rainwater WA flows in through the resin sheet holes 130, but when the soil base is weak, not only water WA flows in through the resin sheet holes 130, but also fine particles CL contained in the soil, which adhere to the nonwoven fabric fibers 122.

[0012] After a long period of time, the areas around the outlets of the resin sheet holes 130 will become clogged with the fine particles CL that have flowed in. Clogging reduces the drainage capacity, and prevents the moisture WA that has flowed in from the resin sheet holes 130 from penetrating and diffusing into the nonwoven fabric sheet 120, preventing it from reaching the soil. As the supply of moisture to the soil below the weed control sheet 100 decreases, as mentioned above, the soil will dry out and lose its strength as a lump of soil.

[0013] When rainwater is supplied to soil that has lost its strength through the gaps at the edges of the resin sheet, the fine particles melt, forming water channels that ultimately lead to the soil collapsing.

[0014] The reduction in the drainage capacity of a nonwoven fabric sheet due to clogging varies depending on the condition of the soil at the installation site, so the through-holes in the weed control sheet need to be individually designed in terms of the thickness or fiber density of the nonwoven fabric part, and the diameter or arrangement density of the through-holes, taking into account the drainage capacity of the nonwoven fabric, posing a challenge that requires a great deal of effort.

[0015] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a soil erosion and weed growth inhibition sheet that prevents the growth of weeds and prevents soil collapse due to environmental factors in soil that protects the aesthetic appearance of slopes and other areas where strong soil is required. [Means for solving the problem]

[0016] In order to solve the above problems, the soil erosion and weed growth inhibition sheet of the present invention is characterized in that in a weed control sheet comprising an impermeable and elastic resin sheet and a nonwoven fabric sheet bonded together, the resin sheet has through holes formed at predetermined intervals from one side to the other, the resin sheet has water-proofing properties and allows a very small amount of rainwater to flow through the through holes into the soil, the nonwoven fabric sheet diffuses the flowed-in rainwater throughout the nonwoven fabric sheet by capillary action and then supplies it to the soil below, thereby maintaining the strength of the soil, and the through holes allow fine particles such as silt and colloids in the soil that have flowed in together with the rainwater to pass through to the soil below.

[0017] In addition, the method for manufacturing a soil erosion and weed growth inhibition sheet of the present invention is characterized in that an uncured, water-impermeable resin sheet and a nonwoven fabric sheet are overlapped and pressed together to entangle and bond the resin sheet and the nonwoven fabric fibers, and then a punching process or a laser drilling process is used to form through holes at predetermined intervals that penetrate from one side to the other side of the bonded resin sheet and nonwoven fabric sheet. Effect of the Invention

[0018] The soil erosion and weed growth inhibition sheet of the present invention (hereinafter referred to as "soil protection sheet 1") is made by laminating a resin sheet and a nonwoven fabric sheet, and thus has excellent light blocking properties and can prevent the growth of weeds. The surface of the soil protection sheet has a water-repellent function that does not retain rainwater, and rainwater does not accumulate on the sheet, so there is no mechanism that promotes plant growth. This makes it possible to prevent the soil from losing its strength due to plant erosion.

[0019] Although the surface material of the soil protection sheet 1 of the present invention is not coated or applied with a water repellent, the resin sheet itself has a water repellent function, so that the surface of the soil protection sheet has a drainage function. Moreover, the through holes are not provided with the function of impregnating the nonwoven fabric sheet with rainwater, but with the function of allowing rainwater, fine soil particles, and silt to fall to the soil below the soil protection sheet by their own weight. Specifically, by providing through holes that penetrate from the resin sheet to the nonwoven fabric sheet and communicate with the soil, fine soil particles and silt that flow in with rainwater through the through holes can be discharged to the soil surface without stagnating and clogging the through holes, which has the effect of preventing a decrease in the drainage ability of the nonwoven fabric.

[0020] On the other hand, rainwater that flows in through the resin sheet through-holes adheres to the fibers of the nonwoven fabric by capillary action, spreads within the nonwoven fabric, and is then drained into the soil below the soil protection sheet, preventing the soil from drying out and allowing it to maintain its strength. This prevents the soil from losing its strength due to weathering.

[0021] Fine particles of soil that flow in with rainwater pass through the through holes that are provided in the nonwoven fabric sheet and communicate with the soil, thereby eliminating the risk of clogging.

[0022] The soil protection sheet of the present invention has a water-proof resin sheet as an upper layer and a nonwoven fabric sheet exhibiting capillary action as a lower layer, and by drilling fine through holes in the sheet, it is possible to supply rainwater and discharge air, and in addition to providing high water-proofing properties, it also has good adhesion between the soil protection sheet and the soil, thereby preventing soil collapse. [Brief description of the drawings]

[0023] [Figure 1] 1 is a perspective view of a soil protection sheet according to the present invention. [Diagram 2] 1 is a plan view of a soil protection sheet according to the present invention. [Diagram 3] 3 is a cross-sectional view taken along the line AA in FIG. 2. [Figure 4] 1 is an example of a soil protection sheet according to the present invention. [Diagram 5] FIG. 2 is an enlarged cross-sectional view showing a through-hole portion of the soil protection sheet according to the present invention. [Figure 6] FIG. 1 is a cross-sectional view of a conventional weed control sheet. [Figure 7] FIG. 1 is an enlarged cross-sectional view showing a hole portion of a resin sheet of a conventional weed control sheet. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment of a soil protection sheet 1 according to the present invention will now be described with reference to the drawings. Fig. 1 is a perspective view of a soil protection sheet 1 according to the present invention.

[0025] The soil protection sheet according to the present invention has a two-layer structure in which a water-impermeable resin sheet and a nonwoven fabric sheet are bonded together.

[0026] The resin sheet is a flat sheet with no gaps that has light-shielding and waterproof properties, while the nonwoven fabric sheet is a sheet of mechanically intertwined fibers.

[0027] The resin sheet is preferably made of silicone resin. The resin sheet itself provides a water-repellent function, and the surface of the soil protection sheet can have a drainage function. Silicone resin is also excellent in elasticity, weather resistance, light-shielding and waterproofing. Polyvinyl chloride has water-proofing properties similar to silicone resin, but in terms of elasticity, polyvinyl chloride has an elongation of 40-80%, whereas silicone resin has an elongation of 80-110%. Other water-proof materials, such as concrete, have no elongation and are prone to cracks and distortion. For vibrations that cause cracks and distortion, it is preferable to use a material with high elasticity, such as silicone resin, as the resin sheet. However, it is not limited to silicone resin, and it is sufficient if it has the same elasticity as silicone resin.

[0028] The nonwoven fabric sheet is preferably made of polyester (PET) nonwoven fabric. PET nonwoven fabric has the effect of mitigating the pressure from the soil by utilizing its cushioning properties. The cushioning properties also have the effect of increasing the strength that is poor in a resin sheet alone. In addition, nonwoven fabric fibers have the characteristic of having a capillary effect, which causes rainwater that flows on the soil side of the resin sheet to spread throughout the nonwoven fabric sheet, and then falls to the soil under its own weight.

[0029] When the resin sheet is made of silicone resin and the nonwoven fabric sheet is made of PET, the thickness of the soil protection sheet is preferably 0.8 mm or more for the silicone resin sheet and 1.0 mm or more for the PET nonwoven fabric sheet, taking into consideration strength, cushioning properties, and water retention due to the capillary phenomenon of the nonwoven fabric, and the thickness of the entire soil protection sheet is preferably 1.8 mm or more. However, taking flexibility into consideration, it is preferable to keep the thickness at 4.0 mm or less.

[0030] FIG. 2 is a plan view of the soil protection sheet according to the present invention. When the soil protection sheet is installed on soil such as a slope for the purpose of weed prevention, the resin sheet is installed on the upper surface and the nonwoven fabric sheet is installed facing the soil side. FIG. 3 shows a cross-sectional view along the line AA in FIG. 2. The soil protection sheet according to the present invention has through holes formed at a predetermined interval, penetrating from one surface to the other surface. Resin sheets with excellent waterproofing are prone to puddles of rainwater on the surface layer, and further soil and sand flow into the puddle, making it easier for weeds to grow. Therefore, through holes are formed at a predetermined interval in the soil protection sheet, and rainwater that accumulates on the surface layer of the soil protection sheet is guided to the soil below the soil protection sheet, preventing puddles.

[0031] If the through-hole diameter is too small, rainwater will not flow into the through-hole due to surface tension. According to the inventor's experiments, it was found that if the hole diameter is 0.3 mm or more, surface tension will not occur. On the other hand, if the through-hole diameter is too large, a large amount of rainwater will flow into the soil below the soil protection sheet, creating water channels, and the strength of the soil will be lost. According to the inventor's experiments, if the hole diameter is larger than 1.2 mm, the water retention limit of the nonwoven fabric sheet having the above-mentioned thickness will be exceeded, and water will flow in the soil below the soil protection sheet, forming water channels. Therefore, the through-hole diameter is preferably 0.3 mm or more and 1.2 mm or less.

[0032] FIG. 2 shows an example in which through holes are provided at a predetermined interval. The interval between the through holes needs to take into consideration the spread of moisture due to the capillary phenomenon of the nonwoven fabric sheet. If the interval is too narrow, the water retention capacity will be exceeded, and water will flow in the soil below the soil protection sheet, forming a water path. According to the experiments of the present inventor, it was found that the nonwoven fabric sheet can maintain water retention if the interval between the through holes is 10.0 mm or more. On the other hand, if the interval exceeds 20.0 mm, moisture will not spread within the nonwoven fabric sheet and will not be evenly distributed in the soil below the soil protection sheet, and the nonwoven fabric sheet will not be able to fulfill the role required of the nonwoven fabric sheet described below. Therefore, the interval between the through holes is preferably 10.0 mm or more and 20.0 mm or less.

[0033] The arrangement pattern of the through holes may be a symmetrical pattern with equal pitch as shown in Fig. 2, or a repeating pattern of a fixed arrangement of through holes such as a houndstooth pattern as shown in Fig. 4. Even in this case, it is preferable to keep the number of through holes per unit area constant.

[0034] When changing the number of through holes per unit area, it is preferable to change the hole diameter. For example, in the case of the arrangement pattern of through holes spaced at regular intervals, for example 10.0 mm intervals, as in Fig. 2, the hole diameter is set to 1.0 mm, and in the case of the houndstooth pattern in Fig. 4 where the intervals between diagonals are shorter, it is preferable to set the hole diameter to 0.5 mm.

[0035] As mentioned above in the background art, fine particles such as silt and colloids in the soil usually form lumps of soil due to the effect of pore water on the soil surface, which maintains its strength, so when covered with an impermeable resin sheet, the soil dries out and the aggregate structure becomes fragile, causing the soil to lose its strength as a lump. The through holes in the soil protection sheet according to the present invention are intended to provide an even and constant supply of moisture to the soil below the soil protection sheet.

[0036] FIG. 5 is an enlarged cross-sectional view showing the through-hole portion of the soil protection sheet according to the present invention. Rainwater on the surface layer of the soil protection sheet penetrates through the through-holes provided at a predetermined interval, passes through the resin sheet portion, and reaches the nonwoven fabric sheet. At that time, most of the rainwater is attracted into the nonwoven fabric sheet due to the capillary phenomenon of the nonwoven fabric. The attracted water is diffused into the nonwoven fabric sheet and then reaches the soil. The moisture penetrates into fine particles such as silt and colloids in the soil, forming lumps of soil and maintaining its strength. As a result, it is possible to prevent the soil from losing its strength due to weathering or erosion by plants.

[0037] Fine particles such as mud and colloids may get into the through-holes. The fine particles pass through the through-holes that connect the resin sheet to the nonwoven fabric sheet and reach the soil below the soil protection sheet. When they do so, they are not attracted to the nonwoven fabric fibers, and the fine particles such as mud and colloids do not remain on the nonwoven fabric sheet.

[0038] As a result, the problem of clogged holes that occurs in conventional weed control sheets has been solved.

[0039] The soil protection sheet according to the present invention was subjected to a performance test under the test conditions shown in Table 1. [Table 1] As a result of the above tests, the soil protection sheet's water impermeability rate was over 97%, which is equivalent to that of concrete.

[0040] It is known that when air accumulates in the soil below a conventional resin sheet laid on a slope, the moisture content and air content (atmospheric air content) differ from those of the soil surrounding the resin sheet, causing the soil to lose its balance and collapse. The through-holes act to collect air present in the soil after rainwater penetrates through the through-holes in the surface of the soil protection sheet and reaches and permeates the soil, and then release the air to the ground surface through the through-holes. The air in the soil is discharged from each of the through-holes to the upper side of the soil protection sheet, causing the soil protection sheet to adhere closely to the soil, thereby preventing soil collapse.

[0041] When a water-permeable sheet is used, both rainwater and air are discharged, but when a large amount of rainwater is supplied from above the sheet, the large amount of rainwater penetrates into the soil below the sheet, creating water paths and causing soil erosion. On the other hand, when a sheet with 100% water impermeability is used, the underside of the sheet dries out, leading to soil erosion. The soil protection sheet of the present invention has a water-impermeable resin sheet in the upper layer and a nonwoven fabric sheet with capillary action in the lower layer, and by opening fine through holes in the soil protection sheet, it is possible to supply water and discharge air, thereby providing a water impermeability of over 97% and adhesion between the soil protection sheet and the soil.

[0042] The method for producing the soil protection sheet according to the present invention will now be described.

[0043] The soil protection sheet according to the present invention is a process in which a resin material and a vulcanizing agent are kneaded together to adjust the thickness, and then a nonwoven fabric sheet formed by piercing a web of overlapping fibers with a needle having a protrusion by, for example, a needle punch method to entangle the fibers is laminated on the uncured resin sheet extruded from a roll machine, and the resin sheet and the nonwoven fabric fibers are entangled and bonded. When bonding different types of materials, it is common to use adhesives or synthetic resins such as polypropylene as adhesive materials, but since the soil protection sheet is exposed to the outdoor environment for a long period of time, there is a concern that hydrolysis due to ultraviolet rays and moisture, even if in small amounts, may occur and the bonding members may peel off. On the other hand, in the method of bonding an uncured resin sheet to a nonwoven fabric, there is no concern of peeling when using adhesives, etc.

[0044] Thereafter, a step of forming through holes at a predetermined interval that penetrate from one side to the other side of the bonded resin sheet and nonwoven fabric sheet by punching or laser drilling is performed to manufacture a soil protection sheet. The drilling is preferably laser processing. In the case of punching a needle into the nonwoven fabric, the nonwoven fabric fibers escape from the needle, making the through holes irregular in shape and causing clogging with fine particles such as silt and colloids in the soil. On the other hand, in the case of laser processing, the nonwoven fabric fibers are burned off with a laser, so the through holes are processed into a stable shape, the hole diameter is narrowed, and the possibility of clogging with fine particles such as silt and colloids in the soil can be suppressed.

[0045] Since the soil protection sheet according to the present invention is often installed near transportation infrastructure, it is preferable to apply an irregular embossing process to the surface of the resin sheet, which reproduces the texture of concrete or stone and reduces reflection of natural light. It is also preferable to apply a grayish color so that it blends in with the transportation infrastructure. [Industrial Applicability]

[0046] The soil protection sheet of the present invention prevents the growth of weeds on flat land and slopes such as roads, developed land, unused land, etc. In particular, it also prevents soil collapse caused by rainwater on slopes. [Explanation of symbols]

[0047] 1. Weed control sheet 10 Resin sheet 20 Nonwoven sheet 22 Non-woven yarn 30 through holes 100 Conventional weed control sheet 110 Resin sheet 120 Nonwoven Sheet 122 Nonwoven fibers 130 Resin sheet hole CL Mud (fine particles contained in soil) WA Moisture (rainwater)

Claims

1. A weed control sheet in which a resin sheet having no water permeability and elasticity and a nonwoven fabric sheet are bonded together, A through hole formed from one surface to the other surface, Provided at predetermined intervals, The resin sheet is It has water-proofing properties, allowing a very small amount of rainwater to flow through the holes into the soil. The nonwoven fabric sheet is The rainwater that flows in is dispersed throughout the nonwoven fabric sheet by capillary action and then supplied to the soil below. The through hole is Allowing fine particles such as silt and colloids in the soil that flow with rainwater to pass through to the soil below; A soil erosion and weed growth inhibition sheet characterized by the above.

2. An uncured water-impermeable resin sheet and a nonwoven fabric sheet are laminated and pressed together to entangle and bond the resin sheet and the nonwoven fabric fibers, and then forming through holes at predetermined intervals through one surface of the resin sheet and the nonwoven fabric sheet bonded together by punching or laser drilling; A method for producing a soil erosion and weed growth inhibition sheet, comprising:

Images