Weed control sheet and weed control sheet molding device

Abstract

Weed control sheets, made from woven plastic, are inexpensive, highly flexible, and easy to handle, making them widely used in fields and greatly contributing to reducing the workload of farmers in weeding. To prevent the weed control sheets from shifting or being blown away by the wind, they are secured to the ground with fixing pins. Generally, U-shaped pins fitted with fixing washers are driven through the weed control sheet and into the ground. However, if the sheets are subjected to strong stress from wind or other factors after installation, the edges around where the fixing pins are driven in can fray, and once frayed, it can fray endlessly. Furthermore, the frayed threads scatter in the fields, worsening the environment. [Solution] A weed control sheet made of thermoplastic woven fabric, with fray-preventing sections of a certain width on both edges, characterized in that the fray-preventing sections are formed by locally melting and molding multiple recesses by heat pressing and welding the warp threads to the weft threads.

Description

Technical Field

[0001] The present invention relates to a weed control sheet made of a woven fabric of thermoplastic plastic and having a fraying prevention structure, and a molding apparatus thereof.

Background Art

[0002] In order to suppress the growth of weeds, various weed control sheets have been proposed. Commercially available ones are mainly classified into non-woven fabrics and woven fabrics. The non-woven weed control sheet is integrally formed into a sheet shape by heat-sealing fibrous materials, and is strong and has an excellent weed control effect, but it is expensive and the material is hard and difficult to handle. The woven weed control sheet is generally plain-woven using flat yarns made of olefin resins such as polyethylene and polypropylene, which are thermoplastic general-purpose plastics. Compared with the non-woven weed control sheet, the weed control effect is lower, but it is inexpensive, highly flexible, and easy to handle. Therefore, farmers mainly use the woven weed control sheet, which greatly helps to reduce weeding work. After the weed control sheet is laid, it is fixed to the ground with fixing pins so that it does not shift or be rolled up and blown away by the wind. Generally, a fixing washer is fitted to a U-shaped pin, which is passed through the weed control sheet from above and driven into the ground.

[0003] The woven weed control sheet is cut by the manufacturer from the original fabric to make individual products. However, since only the cut surface is heat-sealed, when it is subjected to strong stress by wind or the like after laying, it frays from the end surface around where the fixing pin is driven in, and once it frays, it frays indefinitely. Further, the frayed yarns scatter in the field, deteriorating the environment.

[0004] Regarding the fraying from the end face of the woven fabric, a proposal has been made as in Patent Document 1. That is, a sheet formed by weaving a yarn material having a high melting point polymer as a core and a low melting point polymer on its surface for both warp and weft, and an edge tape in which a low melting point polymer is laminated on a high melting point polymer base material are heat-sealed to the sheet to increase the strength of the end.

[0005] Furthermore, as described in Patent Document 2, there is a proposal to form a resin coating layer with a lower melting point than the base fabric on both sides of the flat yarn base fabric of the woven fabric, and then heat-seal a similarly formed strip-shaped sheet to cover the edges of the woven fabric from both sides to form a reinforcing edge. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 4-281040 [Patent Document 2] Japanese Patent Publication No. 2014-156064 [Overview of the project] [Problems that the invention aims to solve]

[0007] To prevent fraying of woven fabrics, it is desirable to fuse the warp and weft threads together completely, as this would also strengthen the entire base fabric. To achieve this, methods such as fusing special materials with surface treatments, such as polymers or resin coatings with a lower melting point than the base material, as described in prior art literature, have been employed. However, these methods have problems with increased productivity and material costs. Fusing edge tapes made of a separate material or folding and fusing the edges significantly increases manufacturing costs and requires special materials for fusing. In the case of woven weed control sheets, where the material has a single melting point, attempting to melt the entire surface causes the base material itself to soften, resulting in deformation or holes, making it difficult to manufacture stably. Currently, no effective fray prevention measures have been implemented. This invention provides a weed control sheet made of thermoplastic plastic, which is inexpensive and has a sturdy, fray-resistant structure.

[0008] Furthermore, this invention provides a weed control sheet molding device that enables the fray-prevention structure to be realized inexpensively, quickly, and stably. [Means for solving the problem]

[0009] The present invention relates to a weed control sheet made of thermoplastic woven fabric, with fray-preventing sections of a certain width provided on both edges, characterized in that the fray-preventing sections are formed by locally melting and molding multiple recesses by heat pressing and welding the warp threads to the weft threads.

[0010] Furthermore, the weed control sheet is characterized in that the fray prevention portion has multiple recesses exposed on the end face and multiple recesses provided inside them, which are formed in a dot pattern at appropriate intervals and with appropriate size and depth.

[0011] Furthermore, the weed control sheet molding apparatus includes a press roller with a press die embedded in its outer circumference for melt-molding recesses to form the fray-preventing portion, a heating unit for heating the press die, and a conveying roller that faces the press roller and grips and conveys the weed control sheet, thereby enabling the continuous formation of the fray-preventing portion. [Effects of the Invention]

[0012] A weed control sheet made of thermoplastic woven fabric, with fray-preventing sections of a certain width on both edges, wherein the fray-preventing sections are formed by locally melting and molding multiple recesses by heat pressing and welding the warp threads to the weft threads, thereby eliminating the need for special materials, surface treatments, or separate edge tapes for welding the warp and weft threads, making it possible to produce a weed control sheet that is inexpensive, highly productive, and has significantly improved durability.

[0013] A weed control sheet molding apparatus is possible that enables the continuous formation of fray-preventing sections in a weed control sheet, by providing a press roller with a press die embedded in its outer circumference for melting and molding recesses, a heating unit for heating the press die, and a conveying roller that faces the press roller and grips and conveys the weed control sheet. [Brief explanation of the drawing]

[0014] [Figure 1] Plan view of a weed control sheet, an embodiment of the present invention. [Figure 2]Side view of a weed control sheet, an embodiment of the present invention. [Figure 3] Side view of a weed control sheet forming machine, which is an embodiment of the present invention. [Figure 4] Front view of a weed control sheet forming machine, which is an embodiment of the present invention. [Figure 5] Plan view showing a weed control sheet with fixing pins driven into it, which is an embodiment of the present invention. [Figure 6] Side view of a weed control sheet with fixing pins driven into it, which is an embodiment of the present invention. [Modes for carrying out the invention]

[0015] Figures 1 and 2 are a plan view and a side view of an embodiment of the weed control sheet according to the present invention. 1 is a weed control sheet made of plain-woven flat yarn of thermoplastic general-purpose plastic, cut from the raw material using a heat-cutting method, and the warp threads in the longitudinal direction and the weft threads perpendicular to them are fused at the end face 2. As shown in Figures 1 and 2, by locally melting and forming semicircular recesses 3 from the end face using a heat press, the area over which the warp and weft threads are welded from the end face is increased, and the prevention of fraying from the end face can be strengthened. It is desirable that the occupancy rate of the recesses 3 exposed on the end face is about half of the end face. Furthermore, circular recesses 4 are welded in a dot-like pattern in a staggered arrangement inside the recesses 3 using a heat press, and by arranging these at appropriate intervals in the longitudinal direction at both ends, a fray-preventing section A is formed in which the warp threads are welded to the weft threads at appropriate intervals. In addition, by leaving a wide area that is not melted, quality difficulties such as deformation of the edges are eliminated. Multiple rows of recesses 4 may be provided depending on their size. The width W of the fray-prevention section A is preferably 4 cm to 6 cm, the depth of the recesses 3 and 4 is preferably about half the sheet thickness, or 0.05 to 0.1 mm, and the diameter is preferably 3 to 4 mm. Furthermore, if recesses 3 and 4 are formed in the same location on both the front and back surfaces of the weed control sheet, a weed control sheet without a distinct front or back surface can be created. In that case, the melting depth of the recesses needs to be shallower.

[0017] Figs. 3 and 4 are schematic views of the main part of a molding machine E for rapidly forming the recesses 3 and 4, which are embodiments of the present invention, in the weed control sheet 1. Press dies 22 for forming a plurality of recesses 3 and 4 are embedded at regular intervals on the outer peripheral surface of a press roller 21. Further, a heating device 23 for heating the press dies 22 and a conveying roller 24 arranged to sandwich the weed control sheet 1 are provided, and the recesses 3 and 4 can be melted and formed in the weed control sheet 1 by the press dies 22 while being conveyed at high speed. The heating device 23 is preferably a high-frequency heating device or the like. The heating temperature of the press dies is preferably 300°C to 400°C although it depends on the conveying speed.

[0018] Figs. 5 and 6 are a plan view and a cross-sectional view showing the laying of the weed control sheet 1 by fixing pins 41, which are embodiments of the present invention. The fixing pins 41 are in an inverted U shape, penetrate the weed control sheet 1 via presser washers 42, and are driven into the ground. The fixing pins 41 are driven into the fraying prevention part A. In order to drive them into the end part so that the weed control sheet 1 does not turn up, when it is fanned by the wind, stress is applied to the driven part, and fraying of the end face is likely to occur, but the fraying prevention part A is formed, so that unrestricted fraying from the end face can be prevented.

Explanation of Reference Numerals

[0019] 1: Weed control sheet 2: End face of weed control sheet 3, 4: Recesses 21: Press roller 22: Press die 23: Heating device 24: Conveying roller 41: Fixing pin 42: Presser washer A: Fraying prevention part E: Weed control sheet molding machine W: Width of fraying prevention part A

Claims

1. A weed control sheet made of thermoplastic woven fabric, with fray-preventing sections of a certain width provided on both edges, characterized in that the fray-preventing sections are formed by locally melting and molding multiple recesses by heat pressing and welding the warp threads to the weft threads.

2. The weed control sheet described in claim 1 is characterized in that the fray prevention portion has a plurality of recesses exposed on the end face and a plurality of recesses provided inside it, which are formed in a dot pattern at appropriate intervals and of appropriate size and depth.

3. A weed control sheet molding apparatus that enables the continuous formation of the fray-preventing portion, comprising a press roller with a press die embedded in its outer circumference for melt-molding a recess, a heating unit for heating the press die, and a conveying roller that faces the press roller and grips and conveys the weed control sheet.

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