Weed control sheets, weed control sheet manufacturing methods, weed control materials, weed control material manufacturing methods

Abstract

The present invention provides a weed control sheet with an easy-to-manufacture structure that does not require removal, and a method for manufacturing the weed control sheet. [Solution] The weed control sheet and weed control material of the present invention are mainly composed of fibers obtained by defibrating the bark of coniferous trees, and are formed into a sheet shape by hardening the lignin present in the bark. The weed control sheet is characterized by the distribution of areas with different degrees of hardening. The weed control sheet manufacturing method of the present invention involves heating and pressurizing fibers derived from the bark of coniferous trees or a material containing them, distributing areas with different molding conditions in a planar manner, thereby hardening the lignin present in the bark and forming it into a sheet shape. The weed control material manufacturing method of the present invention involves heating and pressurizing fibers derived from the bark of coniferous trees or a material containing them, thereby hardening the lignin present in the bark and forming it into a plate shape.

Description

Technical Field

[0001] The present invention relates to a weed control sheet for preventing the growth of weeds, a method for manufacturing the weed control sheet, a weed control material, and a method for manufacturing the weed control material.

Background Art

[0002] As weed control sheets, for example, Patent Documents 1 to 4 are known as prior arts. In the solution means of the summary of Patent Document 1, it is shown that "The cedar bark weed control mat of the present invention is formed in a sandwich shape by laying fiber chip-shaped bark (tree bark) 2 peeled from cedar trees on a biodegradable lower cloth 1 with an appropriate thickness, and further laying a biodegradable upper cloth 3 thereon, and is composed of a biodegradable thread 4 that integrally sews the upper cloth 3, bark 2, and lower cloth 1 formed in this sandwich shape. Therefore, it has excellent water retention and air permeability, has appropriate rigidity, can be cut into an appropriate length from a roll-shaped mat for use, and has the effect of being biodegradable in the long term."

[0003] In the solution means of the summary of Patent Document 2, it is shown that "A weed control material composed of an alkaline soil material and a bark material, which is industrial waste, and the bark material hardly contains xylem and has a high water permeability. Further, the weed control construction method using such a material includes a step of leveling unevenness in the construction area, a step of laying an alkaline soil material, a step of applying a predetermined pressure to the material, a step of giving a predetermined slope to the construction area after rolling, a step of laying a bark material on the material, and a step of low-density scattering of an alkaline soil material on the surface layer of the construction area."

[0004] In the solution means of the summary of Patent Document 3, it is shown that "The weed control and greening sheet S according to the present invention includes a strip-shaped base material bag 2 on a weed control sheet 1. The base material bag 2 is held so as to be exposed on the lower surface side of the weed control sheet 1. A sparse portion 5 with a low weed control function is provided at the holding position of the base material bag 2 on the weed control sheet 1."

[0005] The abstract of Patent Document 4 describes the solution as follows: "This retroreflective weed control sheet is laid at the boundary between a roadway or sidewalk and a curb. This retroreflective weed control sheet is laminated and integrated in the following order from the surface: glass beads 2 embedded in a transparent resin layer 1, an aluminum layer 3, a nonwoven fabric layer 4, and an asphalt layer 5. Due to the glass beads 2 embedded in the transparent resin layer 1 and the aluminum layer 3, when a vehicle's headlights are shone on it at night, the surface appears silvery-gray, allowing the position of the curb to be confirmed. The aluminum layer 3 and the nonwoven fabric layer 4 are made of aluminum-deposited nonwoven fabric."

[0006] Non-patent document 1 provides an explanation regarding the light-blocking rate of weed control sheets. Specifically, it states that at around 500 lux, the amount of CO2 emitted by plants through respiration becomes equivalent to the amount of CO2 fixed by photosynthesis, and that on a clear summer day, the light level can reach around 100,000 lux, so if the weed control sheet has a light-blocking rate of 99.5% or more, plant growth can be inhibited. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2017-099344 [Patent Document 2] Japanese Patent Publication No. 2022-146661 [Patent Document 3] Japanese Patent Publication No. 2023-017166 [Patent Document 4] Japanese Patent Publication No. 2025-070263 [Non-patent literature]

[0008] [Non-Patent Document 1] Shirasaki Corporation, Weed Control Sheet Specialist, Weed Control Sheet.com "Regarding the Light Blocking Rate of Weed Control Sheets", [Searched February 12, 2026], Internet <https: / / www.bousou-sheet.com / docs / course / %E9%98%B2%E8%8D%89%E3%82%B7%E3%83%BC%E3%83%88%E3%81%AE%E9%81%AE%E5%85%89%E7%8E%87%E3%81%AB%E3%81%A4%E3%81%84%E3%81%A6 / ?srsltid=AfmBOooXnbJ0c1n9Yuw2_Up6NDEhxZq0mHkd03VaveY6T1GAr2aLF2Nk> . [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the weed control sheet in Patent Document 1 requires sewing to form a sandwich structure, and therefore requires a sewing machine for manufacturing. The technology in Patent Document 2 is a weed control material consisting of alkaline soil material and bark material, and is not a weed control sheet, so complicated work must be performed on-site. Paragraph 0035 of Patent Document 3 states, "The material of the weed control sheet 1 (warp threads 6 and weft threads 7) may be the same as polyethylene, etc., used in so-called blue sheets." The weed control sheet in Patent Document 4 contains glass beads and an aluminum layer. In other words, the weed control sheets in Patent Documents 3 and 4 need to be removed when they are no longer in use.

[0010] Areas where weed growth needs to be inhibited include land around seedlings after planting in forestry, field edges, road embankments, open spaces in parks and businesses, and vacant lots after land development or demolition of buildings. It is strongly desired that the weed control sheets do not need to be removed when they are no longer needed. In particular, on slopes after planting, it is necessary to inhibit weed growth until the planted trees have grown to a certain extent. Therefore, to improve the productivity of forestry, it is desirable to install weed control sheets over a wide area. However, once the trees have grown to a certain extent, weeds will no longer block sunlight from reaching the trees, and the trees will block sunlight from reaching the weeds, so weed control sheets are no longer necessary. If weed control sheets need to be removed when they are no longer needed, it will require removal work over a wide area, and as a result, productivity improvements will not be achieved.

[0011] In view of these circumstances, the present invention aims to provide a weed control sheet that is easy to manufacture and does not require removal, and a method for manufacturing the weed control sheet. [Means for solving the problem]

[0012] The present invention relates to a weed control sheet and weed control material mainly composed of fibers obtained by defibrating the bark of coniferous trees, and formed by the hardening of lignin present in the bark. The weed control sheet is characterized by the distribution of areas with different degrees of hardening. The weed control sheet manufacturing method of the present invention involves heating and pressurizing coniferous tree bark-derived fibers or a material containing them, distributing areas with different molding conditions in a planar manner, thereby hardening the lignin present in the bark and forming it into a sheet. The weed control material manufacturing method of the present invention involves heating and pressurizing coniferous tree bark-derived fibers or a material containing them, thereby hardening the lignin present in the bark and forming it into a plate. [Effects of the Invention]

[0013] The weed control sheet of the present invention is a non-woven fabric mainly composed of the fibers of the bark of coniferous trees, and the fibers are bonded together by curing the lignin present in the bark. Therefore, it has biodegradability. Also, since it is mainly composed of the fibers of the bark and sufficient light-shielding properties can be obtained, it functions as a weed control sheet or a weed control material. The method for manufacturing the weed control sheet and the method for manufacturing the weed control material of the present invention are formed by performing heating and pressurization. Since no sewing is performed, the manufacturing is easy.

Brief Description of the Drawings

[0014] [Figure 1] A diagram showing the flow of the method for manufacturing the weed control sheet of the present invention. [Figure 2] A diagram showing the state of felled cedar. [Figure 3] A diagram showing the state when the bark of cedar is put into a bucket and fibrillation starts. [Figure 4] A diagram showing the state when fibrillation ends. [Figure 5] A diagram showing the state of a formed sheet obtained by heating and pressurizing the fibers obtained in the fibrillation step at a first temperature and a first pressure. [Figure 6] A diagram showing the state of a weed control sheet obtained by heating and pressurizing the formed sheet at a second temperature and a second pressure. [Figure 7] A diagram showing the state when one of the weed control sheets shown in FIG. 6 is wound around the core 810 of toilet paper. [Figure 8] A diagram showing the images of the preliminary forming step and the main forming step of the example. [Figure 9] A diagram showing the images of the preliminary forming step and the main forming step of Modification 1.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail. Components having the same function are denoted by the same numbers, and redundant explanations are omitted.

Examples

[0016] Figure 1 shows the flow chart of the weed control sheet manufacturing method of the present invention. Figure 2 shows the state of felled cedar trees. In many cases, the interior of older cedar trees becomes hollow, as shown in the cedar tree on the right in Figure 2, making it unusable as timber. Furthermore, the bark of coniferous trees contains components that inhibit plant growth, making it difficult to use as compost. On the other hand, there are examples of using the components that inhibit plant growth to prevent weed growth (e.g., Patent Document 2). The weed control sheet of the present invention is characterized by being mainly composed of fibers obtained by defibrating the bark of coniferous trees, and being formed into a sheet shape by lignin in the bark that has been hardened by heating and pressurizing. "Main component" means the main material that constitutes the weed control sheet. It does not mean that no other materials are included at all. The weed control sheet manufacturing method of the present invention involves heating and pressurizing fibers derived from the bark of coniferous trees or a material containing them, with different molding conditions distributed in a planar manner, thereby hardening the lignin present in the bark and forming it into a sheet shape. For example, the defibration step (S100), pre-forming step (S200), and main forming step (S300) can be performed. "Forming conditions" are conditions determined based on the heating temperature, pressurizing pressure, the moisture content of the fibers (described later), and the amount or thickness of the material containing the fibers.

[0017] The defibration step (S100) involves defibrating the bark of a coniferous tree to obtain fibers. Figure 3 shows the state of a bucket containing cedar bark at the beginning of the defibration process. Figure 4 shows the state at the end of the defibration process. Figure 3(A) shows cedar bark 110 cut to a certain size placed in a bucket 910. Figure 3(B) shows the bark 110 in the bucket 910 being wetted and then beaten with a stick 920. A certain size means approximately 20-30 cm in the direction of the fibers and about 10 cm perpendicular to the fibers. Only the outer bark may be used, or the inner bark may also be included. The ratio of bark 110 to water should be, for example, about 1:1 by weight.

[0018] Figure 4(A) shows the bark 110 becoming fibers 120 as the defibration process nears completion. Figure 4(B) shows the completed defibration process. In the defibration step (S100), defibration is performed on the bark 110 while it is wet, and the fibers 120 are obtained in a wet state. Performing defibration in a wet state allows the fibers 120 to be loosened without being cut in the direction of the fibers, compared to performing it in a dry state. In addition, the wet fibers 120 contain lignin that was present in the bark 110.

[0019] The pre-forming step (S200) involves heating and pressurizing a fiber-containing material at a predetermined first temperature and pressure to form the fibers into a sheet. In the pre-forming step (S200), heating and pressurizing should be applied to the wet fibers 120 obtained in the defibration step (S100). This is because the wet fibers 120 obtained in the defibration step (S100) contain lignin that was present in the bark 110. Figure 5 shows the state of the molded sheet obtained by heating and pressurizing the fibers obtained in the defibration step at a first temperature and pressure. Figure 5 shows four molded sheets 210-1 to 4, each approximately 6 cm wide and 10 cm long. In the example in Figure 5, the "first temperature" was set to 60°C and the "first pressure" to 1 ton, and heating and pressurizing were performed for 10 seconds. When manufacturing a weed control sheet for practical use, for example, a molded sheet of about 1 m x 1.5 m or 1 m x 2 m should be manufactured. The size of the weed control sheet should be determined appropriately according to its intended use.

[0020] The "first temperature" and "first pressure" should be conditions that allow the molded fiber 120 to soften sufficiently, achieve adequate fluidity, and eliminate uneven thickness. Furthermore, the pre-molding step (S200) using the wet fiber 120 obtained in the defibration step (S100) serves two functions: uniform thickness through softening in a wet state (first function) and adjustment to a moisture content suitable for the main molding step (S300) (second function).

[0021] The first function is to improve fluidity and eliminate thickness variations in the defibrated bark by utilizing the softening effect of the bark components in a hydrated state. Components such as lignin and hemicellulose in the bark are known to have a lower glass transition temperature when hydrated, and plastic deformation is more likely to occur even at relatively low temperatures in a wet state. For this reason, in a dry state, almost no deformation occurs under the same conditions and thickness uniformity does not occur, whereas in a wet state, the fibers are rearranged within the defibrated bark, resulting in a molded sheet 210 with homogenized density.

[0022] The second function is to adjust the moisture content to a level suitable for the main molding step (S300). In the main molding step (S300), described later, regions with different degrees of hardening are formed by applying differences in molding conditions (temperature, pressure, ventilation, etc.) within a plane. However, if the moisture content of the material is too high, the thermal conductivity increases due to the moisture, causing heat to diffuse widely within the plane. Furthermore, since moisture acts as a medium for pressure propagation, localized compaction is difficult to occur, and the pressure difference is also leveled out within the plane. As a result, it becomes difficult to effectively reflect the differences in molding conditions (temperature difference, pressure difference) within the plane, and the intended degree of hardening cannot be obtained. In the preliminary molding step (S200), excess moisture is gradually released during the heating and pressurizing process, so the moisture content is adjusted to a level in which the differences in molding conditions within the plane can be effectively reflected in the main molding step (S300). Note that the explanations of the first and second functions are for the purpose of aiding understanding and are not essential functions for the present invention.

[0023] In this molding step (S300), the molded sheet 210 is heated and pressurized at a predetermined second temperature and second pressure. However, the second temperature is higher than the first temperature, and the second pressure is higher than the first pressure. Figure 6 shows the state of the weed control sheet obtained by heating and pressurizing the molded sheet at the second temperature and second pressure. Both sides are shown in Figures 6(A) and 6(B). In the example of the weed control sheet 310 shown in Figure 6, the molded sheet 210 was heated and pressurized for 10 seconds at a "second temperature" of 160°C and a "second pressure" of 3 tons. In addition, one side of the pressurized surface was a flat plate, and 40 M6 cap nuts were arranged in a square grid on the other side. In other words, in the pressurization in this molding step (S300), a pressurized surface with distributed irregularities was used. Therefore, regions with different molding conditions are distributed in this molding step. Because the irregularities are arranged in a grid, the regions with different molding conditions are distributed periodically. Furthermore, the convex parts of the uneven surface are spherical. By making the convex parts spherical, the thickness of the weed control sheet 310 can be changed gradually, creating a structure with a continuously changing degree of hardening. By forming a hardening gradient in this way, stress concentration when the weed control sheet 310 is bent can be reduced, making it more flexible. It should be noted that if the thickness of the weed control sheet 310 can be changed gradually and a structure with a continuously changing degree of hardening can be created, it is not necessary to limit it to a spherical surface; a pressure surface with an inclination can be used.

[0024] Figure 7 shows one of the weed control sheets shown in Figure 6 wrapped around a toilet paper roll core 810. During pressurization, a pressurized surface with a grid-like pattern of irregularities is used to distribute and maintain the flexibility of the molded sheet 210. Furthermore, by making the convex parts spherical, the degree of flexibility can be changed gradually. Therefore, even large weed control sheets can be rolled up, making them easy to transport. Whether to use a pressurized surface with irregularities, the spacing of the irregularities if a pressurized surface is used, whether to make the convex parts spherical or not, and the curvature if spherical should be determined by considering the size and application of the weed control sheet. In the example in Figure 6, a pressurized surface with a grid-like pattern of irregularities was used, but in order to make it easier to roll up, areas with different degrees of lignin hardening should be distributed so that flexibility can be distributed and maintained. To achieve this, heating and pressurization should be performed with areas with different molding conditions distributed over a surface.

[0025] Figure 8 shows an image of the pre-forming step and the main forming step of this embodiment. Figure 8(A) shows the pre-forming step, Figure 8(B) shows the main forming step, and Figure 8(C) shows a cross-section of the weed control sheet. In the pre-forming step (S200), heating and pressurization are performed using a plate 220 with a flat pressurizing surface and a flat plate 900. Then, in the main forming step (S300), heating and pressurization are performed using a plate 320 with a pressurizing surface having irregularities 321 and a flat plate 900. As a result, a weed control sheet 310 having recesses 311 is manufactured. The region 312 with a high degree of hardening is the part of the weed control sheet 310 that is thin, and the region 313 with a low degree of hardening is the part of the weed control sheet 310 that is thick.

[0026] The weed control sheet of the present invention is a nonwoven fabric mainly composed of coniferous tree bark fibers, with the fibers bonded together by hardening the lignin present in the bark. Therefore, it is biodegradable. Furthermore, because it is mainly composed of bark fibers, the weed control sheet shown in Figure 6 provides sufficient light blocking (99.5% or more), thus functioning as a weed control sheet. The manufacturing method of the weed control sheet of the present invention involves heating and pressurizing at a first temperature and a first pressure to obtain a molded sheet, and then heating and pressurizing at a second temperature and a second pressure. Since no stitching is required, manufacturing is easy. Although the coniferous tree shown in the experiment was Japanese cedar, similar effects can be obtained with Japanese cypress.

[0027] The bark stripped from felled cedar trees is often incinerated because it is difficult to use as compost, and since the quantity is large, there is a desire for its effective utilization. Cedar bark contains a relatively large amount of uniform lignin, so if the lignin it contains is actively utilized, there is no need to add adhesive to bind the fibers together. It is suitable as a raw material for the weed control sheet of the present invention. In addition, coniferous trees often have bark that contains phenols and other components that inhibit plant growth, so in addition to weed control by shading, the effect of components that inhibit weed growth can also be expected. The same applies to cypress. It should be noted that, although there may be differences in degree, other coniferous trees also contain both lignin and components that inhibit plant growth, so some effect can be expected from them as well. [Example 1]

[0028] The flow of the weed control sheet manufacturing method for Modification 1 is the same as in Figure 1. Figure 9 shows an image of the pre-forming step and the main forming step of Modification 1. Figure 9(A) shows the pre-forming step, Figure 9(B) shows the main forming step, and Figure 9(C) shows a cross-section of the weed control sheet. In the pre-forming step (S200), heating and pressurization are performed using a plate 230 having a pressure surface with irregularities 231 and a flat plate 900. Then, in the main forming step (S300), heating and pressurization are performed using a plate 330 having a flat pressure surface and a flat plate 900.

[0029] By manufacturing in this manner, during the pre-forming step (S200), heating and pressurizing at a first temperature and pressure softens the fibers 120, providing sufficient fluidity. The material containing the fibers 120 moves along the irregularities 231, creating a molded sheet 212 with regions of varying material thickness. Regions with convex portions 213 in the molded sheet 212 are regions with thicker material containing the fibers 120. By making the shape of the concave portions spherical, a slope can be created at the boundary of the irregularities. Because regions of varying material thickness are distributed, even if heating and pressurizing are performed using a plate 330 with a flat pressurizing surface and a flat plate 900 in the main molding step (S300), regions with varying molding conditions can be distributed. Since regions with varying molding conditions are distributed, the degree of lignin hardening can also be distributed. Furthermore, if a slope exists at the boundary between the concave and convex portions of the irregularities 231, a gradient can be created in the degree of hardening. Therefore, stress concentration when bending can be reduced. Making the recesses spherical is one way to create a slope at the boundary between the recesses and the convex parts. The slope does not necessarily have to be spherical. By periodically distributing the irregularities 231, it is possible to periodically distribute regions with different molding conditions (regions with different degrees of lignin hardening).

[0030] As a result, a weed control sheet 315 can be manufactured that is flat on both sides and has a distribution of areas 312 with a high degree of hardening and areas 313 with a low degree of hardening. The weed control sheet 315 is a nonwoven fabric mainly composed of conifer bark fibers, and the fibers are bonded together by hardening the lignin present in the bark. Therefore, it is biodegradable. In addition, sufficient light blocking (99.5% or more) is obtained, so it functions as a weed control sheet. In the weed control sheet manufacturing method of Modification 1, a molded sheet is obtained by heating and pressurizing at a first temperature and a first pressure, and then heating and pressurizing are performed at a second temperature and a second pressure. Since no stitching is performed, it is easy to manufacture. Also, since the weed control sheet 315 is flat on both sides, it can be laid in a way that prevents weed seeds from accumulating regardless of which side is facing up. [Differentiation 2]

[0031] Up to this point, we have described weed control sheets that can be bent into a roll shape and their manufacturing method, with the aim of preventing weed growth over a large area. However, there may also be applications where weed growth is prevented in the gardens of ordinary households. If the target area is relatively small, bending into a roll shape is not required. In such cases, the weed control material used should mainly consist of fibers obtained by defibrating the bark of coniferous trees, and can be formed into a plate shape by uniformly hardening the lignin present in the bark. For example, uniform heating and pressurizing can be applied to fibers derived from the bark of coniferous trees or materials containing them, hardening the lignin present in the bark and forming it into a plate shape. In this case, there is little need to divide the process into a preliminary molding step and a final molding step; heating and pressurizing can be applied to flat plates.

[0032] The weed control material is a nonwoven fabric primarily composed of conifer bark fibers, with the fibers bonded together by hardening the lignin present in the bark. Therefore, it is biodegradable. It also provides sufficient light blocking (over 99.5%), making it functional as a weed control material. It is easy to manufacture as it is formed by heating and pressurizing without stitching. Furthermore, in the case of plate-shaped weed control material, it is suitable for use under the foundations of outdoor facilities, in planting areas, temporary pathways, and as protective mats. It should be provided with the appropriate bending rigidity and load-bearing capacity for each application. Since both sides of the plate-shaped weed control material are flat, it can be laid in a way that prevents the accumulation of weed seeds regardless of which side is facing up. [Explanation of Symbols]

[0033] 110 Bark 120 fibers 210,212 molded sheets 310,315 Weed control sheets

Claims

1. It mainly consists of fibers obtained by dissecting the bark of coniferous trees. The lignin present in the bark hardened and formed into a sheet. It is a weed control sheet, Regions with different degrees of hardening are distributed. A weed control sheet characterized by the following features.

2. A weed control sheet according to claim 1, The aforementioned coniferous tree is either Japanese cedar or Japanese cypress. A weed control sheet characterized by the following features.

3. A weed control sheet according to claim 1, The regions with different degrees of hardening are distributed periodically. A weed control sheet characterized by the following features.

4. The weed control sheet according to claim 3, A gradient of hardening exists between regions with different degrees of hardening. A weed control sheet characterized by the following features.

5. A weed control sheet according to claim 1, In the areas where the degree of hardening is high, the thickness of the weed control sheet is thin. A weed control sheet characterized by the following features.

6. The weed control sheet according to claim 5, The thickness of the weed control sheet is changing gradually. A weed control sheet characterized by the following features.

7. A weed control sheet according to any one of claims 1 to 6, The weed control sheet is rolled up in a roll. A weed control sheet characterized by the following features.

8. A material derived from the bark of a coniferous tree, or a material containing such material, is subjected to heating and pressurizing with different molding conditions distributed across the surface, thereby hardening the lignin present in the bark and forming it into a sheet. A method for manufacturing a weed control sheet, characterized by the following features.

9. The defibration step involves breaking down the bark of coniferous trees to obtain fibers, A pre-forming step in which a material containing the aforementioned fibers is heated and pressurized at a predetermined first temperature and first pressure to obtain a molded sheet in which the fibers are formed into a sheet, This molding step involves heating and pressurizing the aforementioned molded sheet at a predetermined second temperature and second pressure, It has, The second temperature is higher than the first temperature, and the second pressure is higher than the first pressure. Regions with different molding conditions in the aforementioned molding step are distributed. A method for manufacturing a weed control sheet, characterized by the following features.

10. A method for manufacturing a weed control sheet according to claim 8 or 9, The regions with different molding conditions are distributed periodically. A method for manufacturing a weed control sheet, characterized by the following features.

11. A method for manufacturing a weed control sheet according to claim 9, The pressing in the aforementioned molding step is performed using a pressing surface with a distributed uneven surface. A method for manufacturing a weed control sheet, characterized by the following features.

12. A method for manufacturing a weed control sheet according to claim 11, The protrusions of the aforementioned irregularities are spherical. A method for manufacturing a weed control sheet, characterized by the following features.

13. A method for manufacturing a weed control sheet according to claim 9, The pressing in the aforementioned pre-forming step is performed using a pressure surface with a distributed uneven surface. A method for manufacturing a weed control sheet, characterized by the following features.

14. A method for manufacturing a weed control sheet according to claim 13, A slope exists at the boundary between the recessed and convex portions of the aforementioned uneven surface. A method for manufacturing a weed control sheet, characterized by the following features.

15. A method for manufacturing a weed control sheet according to claim 13, The pressing in the molding step described above is performed using a flat pressing surface. A method for manufacturing a weed control sheet, characterized by the following features.

16. A method for manufacturing a weed control sheet according to claim 8 or 9, The regions with different molding conditions are defined by distributing regions with different material thicknesses. A method for manufacturing a weed control sheet, characterized by the following features.

17. A method for manufacturing a weed control sheet according to claim 8 or 9, The aforementioned fibers are obtained by defibrillating the bark while it is wet. Heat and pressure are applied to the aforementioned fibers while they are wet. A method for manufacturing a weed control sheet, characterized by the following features.

18. It contains materials mainly composed of fibers obtained by dissecting the bark of coniferous trees. The lignin present in the bark hardened and formed into a plate-like shape. A weed control material characterized by the following features.

19. Fibers derived from the bark of coniferous trees or materials containing them are heated and pressurized to harden the lignin present in the bark and form it into a plate-like shape. A method for manufacturing weed control material characterized by the following features.

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