JPH04336109A - Permeable sheet for civil work - Google Patents

Abstract

PURPOSE:To improve the permeability and compressive strength of a sheet by linedly providing undulating rows provided in series with many projections whose surface and back adjoin mutually so as not to be parallel to the direction of a mash. CONSTITUTION:A net-shaped sheet 1 made of polypropylene resin or the like and an undulating row provided in series with many projections adjoining mutually on the surface and back of a sheet 1 are linedly provided so as to be oblique as much as 30 deg.-60 deg. to the direction of a mesh 3. In addition to that, the many projections can be provided in series on both the surface and back of the sheet to form the undulating row.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a water-permeable sheet for civil engineering. Specifically, the present invention relates to a water permeable sheet having water permeability and strength and used as a drain material, a greening mat, etc.

0002

[Prior Art] Conventionally, permeable sheets for civil engineering have been made by intertwining a large number of threads made of natural plant fibers such as coconut shell or thermoplastic synthetic resins such as polypropylene and forming them into a mat shape. Ta. However, this water-permeable sheet had low compressive strength and high surface specific gravity, making it inconvenient to handle. Furthermore, the manufacturing process was relatively complicated, and it was difficult to make the thickness uniform.

[0003] As a water-permeable sheet for civil engineering that is lighter in weight and has a simpler manufacturing process, there is a reticulated thermoplastic resin synthetic sheet having undulating rows in which a large number of continuous protrusions are alternately arranged on the front and back sides. A general method for producing this sheet is to thermoform a reticulated thermoplastic synthetic resin sheet using a mold having a large number of columnar protrusions placed in opposition. However, when the protrusion row of the mold and the mesh of the net-like sheet are made parallel, there is a problem in that the elongation rate of the resin becomes significantly large in the intermediate portion between two consecutive protrusions. For this reason, depending on the type of resin and the degree of protrusion depth, the threads in this part may be cut during molding, or even if they are not cut, the threads in this part become extremely thin and the sheet Overall, this resulted in a decrease in compressive strength, and the conventional strength problems could not be improved.

0004

Problem to be Solved by the Invention The problem to be solved by the present invention is that, in particular, on the side surface between two successive protrusions that alternate on the front and back sides of a reticulated thermoplastic synthetic resin sheet,
The goal is to minimize the elongation rate of the mesh threads. The purpose of this is to make the elongation rate of the resin uniform over the entire surface of the sheet and to provide a water-permeable sheet having stable compressive strength.

[0005]

[Means for Solving the Problems] The most important feature of the present invention is that rows of undulations in which a large number of protrusions are connected alternately on the front and back are arranged so as not to be parallel to the mesh direction. do. As a result, the elongation rate of the resin on the side surface between the two protrusions of the undulating row was made relatively small.

[0006]

[Example] Two molds each having a large number of cylindrical protrusions each having a height of 10 mm and a diameter of 5 mm arranged in rows at 20 mm intervals were arranged facing each other (Fig. 4).
A mesh sheet made of polypropylene resin heated to 0 degrees and having a basis weight of 380 g/m2 and a thread pitch of 3 mm is heated at 30 degrees and 45 degrees in the mesh direction with respect to the projection row of the mold.
Then, the two molds are brought close to each other so that the protrusions of one enter into the center between the protrusions of the other (Fig. 5), and a large number of continuous protrusions on both the front and back are connected. A reticulated sheet having undulating rows was obtained. The angle between the undulating rows of the resulting mesh sheet and the mesh is 30 degrees for those inserted at 30 degrees, parallel for those inserted at 45 degrees, and 90 degrees for those inserted at 45 degrees.
The angle of insertion was 45 degrees.

[0007] This reticulated sheet was compressed according to JIS-K7208 with a compressive strength of 2 mm/min, and the compressive yield point load was measured. As a result, when the angle between the relief row and the mesh direction is 30 degrees, it is 0.42Kg/cm2, and when it is 45 degrees, it is 0.53Kg/cm2.
/cm2, and in parallel it was 0.19Kg/cm2. That is, the mesh sheet of the present invention in which the angles formed between the protrusion rows and the mesh direction are 30 degrees and 60 degrees has a compressive strength of 2 to 2.5 times that of the conventional mesh sheet in which the projections are parallel.
It was found that the amount doubled.

[0008] The mesh sheet made of polypropylene resin used in this example is obtained by heat-sealing polypropylene resin threads that are crossed and stacked so that the length and breadth are perpendicular to each other using a heat press (Fig. 1). ). Here, the resin threads are not limited to those running perpendicularly, but also those that are diagonal can be used in the same manner (FIG. 2). Alternatively, a net-like shape can be obtained by punching a large number of holes in a thermoplastic synthetic resin sheet (FIG. 3). In addition to polypropylene, many other thermoplastic synthetic resins can be used, but particularly hard thermoplastic resins such as hard polyvinyl chloride, polystyrene, polyethylene, nylon, polyester, and ABS resin are preferred.

[0009] The water-permeable sheet obtained in this example has a large number of protrusions that are alternately continuous on the front and back sides and are arranged in rows and columns to form undulating rows (FIG. 6). On the other hand, a large number of protrusions that alternately continue on the front and back sides may be connected in one direction, either vertically or horizontally, to form an undulating row (FIG. 7). The angle between the relief row and the mesh direction is preferably 30 degrees to 60 degrees. In this case, the supplementary angle will be 120 degrees to 150 degrees.

A more preferable arrangement of the protrusion rows is such that all the protrusion rows, which are formed by connecting a large number of continuous protrusions on both the front and back surfaces, are arranged in such a way that they are not parallel to the mesh direction. (Figure 9). With this arrangement, it is possible to reduce the elongation of the resin on the side surfaces between the protrusions even for protrusions that are consecutively adjacent to each other on the same surface.

[0011]

Effects of the Invention As described above, in the mesh sheet of the present invention, on the side surfaces of the protrusions, especially on the side surfaces between the continuous protrusions and the depressions, the threads of the mesh are Since it is positioned obliquely, the elongation rate of the resin per unit length is lower compared to the conventional parallel position. This makes it possible to provide a water-permeable sheet with good water permeability and significantly improved compressive strength.

[Brief explanation of drawings]

[Figure 1] Explanatory diagram showing an example of the shape of a reticulated sheet before molding

[Fig. 2] An explanatory diagram showing another example of a reticulated sheet before molding

[
Figure 3: An explanatory diagram showing another example of a reticulated sheet before molding

[Figure 4] Explanatory diagram showing the shape and arrangement of the mold

[Fig. 5] An explanatory diagram showing the state of forming a mesh sheet using a mold.

[Fig. 6] Explanatory diagram showing an example of arrangement of relief rows

[Fig. 7] Explanatory diagram showing another example of arrangement of relief rows

[Fig. 8] Partially enlarged perspective view of a water-permeable sheet according to the present invention

[Fig. 9] Partially enlarged perspective view of a water-permeable sheet according to the present invention.

[Explanation of symbols]

1...Mesh sheet 2...Resin thread 3...Mesh 4...Mesh direction (vertical) 5...Mesh direction (horizontal) 6...Mold 7...Columnar projections 8...・Protrusions 9...Indentations 10...An undulating row in which a large number of protrusions are connected, alternating from front to back.

Claims (2)

[Claims] Claim 1: A net-like sheet made of thermoplastic synthetic resin, which has rows of undulations in which a large number of protrusions are connected alternately on the front and back, and the rows of undulations are not parallel to the mesh direction. A water-permeable sheet for civil engineering, characterized by being arranged in rows. 2. A net-like sheet made of thermoplastic synthetic resin, which has rows of undulations in which a large number of continuous protrusions are connected on both the front and back surfaces, and all the rows of undulations are parallel to the mesh direction. A water-permeable sheet for civil engineering, characterized by being arranged in rows to prevent