JP2975166B2 - Permeable sheet for civil engineering - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permeable sheet for civil engineering. More specifically, the present invention relates to a water-permeable and strong water-permeable sheet used as a drain material, a greening mat or the like.

[0002]

2. Description of the Related Art Conventionally, as a water-permeable sheet for civil engineering, there is a water-permeable sheet formed by mating a large number of yarns made of natural plant fibers such as palms and thermoplastic synthetic resins such as polypropylene with each other to form a mat. Was. However, this permeable sheet has a low compressive strength, a large surface specific gravity, and is inconvenient to handle. Further, the manufacturing process is relatively complicated, and it is difficult to make the thickness uniform.

As a water-permeable sheet for civil engineering which is lighter and has a simple manufacturing process, there has been a net-shaped thermoplastic resin composite sheet having an undulating row in which a large number of continuous projections are alternately arranged on the front and back. A general method for producing this sheet is by thermoforming a reticulated thermoplastic synthetic resin sheet using a mold having a large number of columnar projections opposed to each other. However, when the projection row of the mold and the mesh of the net-like sheet are parallel to each other, there has been a problem that the elongation rate of the resin is significantly increased in the intermediate portion between the two projecting portions that project continuously. For this reason, depending on the type of the resin and the degree of the protruding depth, even if the yarn in this portion is cut during molding, or even if it is not cut, the yarn in this portion becomes extremely thin, so the sheet As a whole, the compression strength was reduced, and the conventional strength problems were not improved.

[0004]

The problem to be solved by the present invention is that the reticulated thermoplastic synthetic resin sheet, particularly on the side face between two projecting portions that are alternately continuous on the front and back sides,
The aim is to minimize the elongation of the mesh yarn portion. Accordingly, an object of the present invention is to provide a water-permeable sheet having a uniform compressive strength over the entire surface of the resin and having stable compressive strength.

[0005]

The most important feature of the present invention is that a row of undulations in which a large number of protrusions that are alternately arranged on the front and back are connected is not parallel to the mesh direction. I do. Thereby, the elongation rate of the resin on the side surface between the two protruding portions of the undulating row is relatively reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Two molding dies having a number of columnar projections having a height of 10 mm and a diameter of 5 mm arranged at intervals of 20 mm are arranged to face each other (FIG. 4).
A mesh sheet made of a polypropylene resin heated to 0 degrees and having a basis weight of 380 g / m2 and a yarn pitch of 3 mm was placed at a mesh direction of 30 degrees and 45 degrees with respect to the row of projections of the mold.
The two molds are brought close to each other so that one protrusion enters the center between the other protrusions (FIG. 5), and a large number of protrusions continuous on both front and back surfaces are connected. Thus, a net-like sheet having undulating rows was obtained. The angle between the undulating rows of the obtained mesh sheet and the mesh is 30 degrees when inserted at 30 degrees, parallel when inserted at 45 degrees, and 90 degrees.
What was inserted in degrees was 45 degrees.

[0007] This mesh sheet is JIS-K7208, pressure
The material was compressed at a compression speed of 2 mm / min, and the compression yield point load was measured. As a result, when the angle between the undulating rows and the mesh direction is 30 degrees, 0.42 kg / cm2, and when the angle is 45 degrees, 0.53 kg / cm2.
g / cm2, and 0.19 kg / cm2 in parallel. That is, the mesh sheet of the present invention in which the angle between the projection row and the mesh direction is 30 degrees and 60 degrees has a compressive strength twice or more as compared with a conventional mesh sheet that is parallel.
It was found to be 2.5 times.

The polypropylene resin mesh sheet used in the present embodiment is obtained by heat-sealing polypropylene resin yarns which overlap each other so that their length and width are orthogonal to each other (FIG. 1). ). Here, the resin thread is not limited to the straight thread, but can be used similarly even if it is oblique (FIG. 2). Alternatively, the sheet can be formed into a net shape by punching out a large number of holes in the thermoplastic synthetic resin sheet (FIG. 3). In addition to polypropylene, many other thermoplastic synthetic resins can be used, but hard thermoplastic resins such as hard polyvinyl chloride, polystyrene, polyethylene, nylon, polyester, and ABS resin are particularly preferable.

In the water-permeable sheet obtained in this embodiment, a large number of projections, which are alternately arranged on the front and back, are arranged vertically and horizontally to form an undulating row (FIG. 6). On the other hand, a large number of projections continuous alternately on the front and back may be connected in one of the vertical and horizontal directions to form an undulating row (FIG. 7). The angle between the undulating rows and the mesh direction is preferably 30 degrees to 60 degrees. In this case, the supplementary angle is 120 degrees to 150 degrees.

[0010] A more preferable arrangement of the projection rows is such that all of the projection rows formed by connecting a large number of continuous projections on both front and back surfaces are not parallel to the mesh direction. (FIG. 9). In this arrangement, the extension of the resin on the side surface between the protrusions can be reduced even for the protrusions adjacent to the same surface.

[0011]

As described above, in the reticulated sheet of the present invention, the thread portion of the mesh on the side surface of the projection, particularly on the side surface between the continuous projection portion and the depression, extends in the height direction. Since the resin is positioned obliquely, the elongation of the resin per unit length is smaller than that of a conventional resin positioned in parallel. This makes it possible to provide a water-permeable sheet having good water permeability and significantly improved compressive strength.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of the shape of a mesh sheet before molding.

FIG. 2 is an explanatory view showing another example of the mesh sheet before molding.

FIG. 3 is an explanatory view showing another example of the mesh sheet before molding.

FIG. 4 is an explanatory view showing the shape and arrangement of a molding die.

FIG. 5 is an explanatory view showing a state in which a reticulated sheet is formed by a forming die.

FIG. 6 is an explanatory diagram showing an example of an array of undulating rows.

FIG. 7 is an explanatory view showing another example of the arrangement of the undulating rows.

FIG. 8 is a partially enlarged perspective view of a water-permeable sheet according to the present invention.

FIG. 9 is a partially enlarged perspective view of a water-permeable sheet according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mesh sheet 2 ... Resin thread 3 ... Mesh 4 ... Mesh direction (longitudinal) 5 ... Mesh direction (horizontal) 6 ... Mold 7 ... Columnar protrusion 8. · Projection 9 ··· Depression 10 ··· Undulating row in which a large number of continuous protruding parts are connected alternately front and back 11 ··· Undulating row in which a large number of continuous protruding parts are connected

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) E02D 3/00 102

Claims (2)

(57) [Claims] 1. A reticulated sheet made of a thermoplastic synthetic resin , wherein a large number of protrusions are alternately formed on both sides of the entire sheet.
Have a continuous undulating row, and are arranged in a row so that the undulating row is not parallel to the mesh direction. 2. A reticulated sheet made of a thermoplastic synthetic resin, comprising a plurality of projecting portions on both front and back surfaces over the entire sheet.
Has a continuous undulating row, and is arranged so that all undulating rows are not parallel to the mesh direction.