JPH11241264A - Three-dimensional netty structure and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject cushionable composite resistant to tensile breakage and having large voids. SOLUTION: This flat plate-like three-dimensional netty structure with randomly spiral linear thermoplastic resin threads point-bonded to one another is so designed that the percentage of voids on one or both surface(s) thereof is lower than that at the central portion thereof. This structure 3 is obtained by the following process: a molten thermoplastic resin is extruded via a plurality of nozzles 4 downward and allowed to descend spontaneously into a space between a pair of belt conveyors 1 partly dipped into water, and subjected to takeup at a speed lower than the descending speed, wherein the space between the pair of belt conveyors 1 is narrower than the width of the extruded molten resin 5 bundle, and, before the belt conveyors 1 run into the water, one or both surfaces of the molten resin 5 bundle come into contact with the belt conveyors 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cushion member,
The present invention relates to a three-dimensional net-like structure having voids used for water treatment materials, filter materials, culvert drainage materials, base materials for slope greening, and the like.

[0002]

2. Description of the Related Art As a method for producing a three-dimensional network structure having voids, a method described in Japanese Patent Publication No. 50-39185 or a three-dimensional network structure is obtained by crimping a monofilament, applying an adhesive and adhering intersections. And the like are known.

A three-dimensional network structure manufactured by a conventional method exhibits excellent elasticity in terms of compressive properties due to its structure. However, the three-dimensional network structure has a structure in which a skeleton is helical and its intersection is bonded or welded. However, when a tensile stress or a bending stress is applied, there is a disadvantage that the intersections are relatively easily peeled off and the three-dimensional network structure does not function sufficiently.

When a three-dimensional network structure manufactured by a conventional method is used as a drainage material for culverts for civil engineering, large voids in the three-dimensional network structure have a function as a drainage channel. In order to improve the porosity, the porosity usually has a porosity of 85% or more. However, a non-woven fabric such as a nonwoven fabric having a relatively low porosity is provided around the three-dimensional network structure so that soil particles do not enter the cavities and cause clogging. It was necessary to wind a filter material, and a process of attaching a nonwoven fabric to the manufactured three-dimensional net-like structure was indispensable, and it was difficult to say that it was reasonable in terms of manufacturing.

Further, when a three-dimensional network structure manufactured by a conventional method is used as a base material for greening a slope, a large-sized space in the three-dimensional network structure is entangled with a spraying material for greening, and the spraying material for greening is formed. It has a porosity of 85% or more so that the sprayed material easily enters the inside of the three-dimensional network structure. However, since the tensile strength of the three-dimensional network structure is weak, the weight of the spray material is small. In some cases, the three-dimensional network structure was broken.

[0006]

In the present invention, in order to solve the above-mentioned problems, a cushion material, a water treatment material and a filter material which are difficult to be pulled or bent and a culvert which secures a sufficient amount of flowing water and hardly allows soil particles to enter therein. An object of the present invention is to provide a three-dimensional net-like structure as a base material for slope greening, in which a drainage material and a spraying material are easily entangled and hard to break, in a rational and economical manner.

[0007]

According to the study of the present inventor, a flat three-dimensional net-like structure to which a random spiral linear thermoplastic resin is point-adhered has a linear shape from the surface in the thickness direction. Provided is a flat three-dimensional net-like structure in which the porosity of both surfaces or one surface is lower than the porosity of the central portion excluding the surface portion up to a distance of 1 to 3 times the wire diameter of the thermoplastic resin. Thought it reasonable.

As one of the methods for obtaining the three-dimensional network structure of the present invention, the molten thermoplastic resin is extruded downward from a plurality of nozzles, and is naturally lowered between a pair of partially conveyed belt conveyors. When the three-dimensional net-like structure is manufactured by taking it slower than the descending speed of the molten resin, the interval between the pair of belt conveyors is narrower than the width of the extruded molten resin bundle, and the molten resin is removed before the belt conveyor is submerged. Both sides or one side of the bundle were brought into contact with the belt conveyor.

That is, both or one surface portion of the molten thermoplastic resin bundle falls onto the belt conveyor, moves inside the molten thermoplastic resin bundle, and becomes a dense state. That is, the porosity is smaller than that of the central part where the liquid has fallen. As a matter of course, the surface portion where the porosity is low has a larger number of intersections than the central portion where the porosity is high, and the tensile strength is significantly increased. In addition, the surface portion having a low porosity has a small area of the void portion, resulting in a fine filter layer.

As a result of the study of the present invention, the porosity of the surface portion is preferably in the range of 10% to 80% in order to function as a filter layer for culvert drainage, though it depends on the local soil used. Was obtained. That is, if the porosity of the surface portion is lower than 10%, clogging with soil particles is likely to occur, and if the porosity is higher than 80%, the soil particles easily pass through.

[0011] Further, in order to exhibit sufficient tensile strength as an industrial material, it was found that the porosity of the surface should be at least 80% or less, depending on the resin used. That is, when the porosity of the surface portion was larger than 80%, the tensile strength was not improved as expected, and only about 10 to 30% was improved. About the porosity of this surface part,
Depending on the use of the three-dimensional net-like structure, it may be appropriately designed in the range of 10% or more and 80% or less.

Further, the three-dimensional net-like structure is made of a cushion material,
When used as a water treatment material, a substrate for slope greening, etc., if the porosity at the center exceeds 98%, it is difficult to mold as a structure with only voids. It is difficult to sufficiently exhibit functions as a three-dimensional network structure such as water-based properties and air permeability.

Here, the surface portion is a portion having a distance of 1 to 3 times the wire diameter from the surface. Due to the structure of the three-dimensional network structure of the present invention, the wires are dense at the surface, and there are portions where the wires overlap each other. When the porosity is in the range of 10% or more and 80% or less, the wires are used. However, it was confirmed that up to about three portions overlapped. The wire diameter is the diameter of the wire that constitutes the three-dimensional net-like structure when the cross-sectional shape is circular.If the cross-sectional shape is not circular, such as square, the cross-section is assumed to be circular. And the diameter obtained from the cross-sectional area.

The thermoplastic resin used here includes polyolefins such as polyethylene and polypropylene,
Normal extrusion of not only polyesters such as polyethylene terephthalate, polyamides such as nylon 66, but also polyvinyl chloride, polystyrene, or copolymers or elastomers copolymerized based on the above resins, or polymer blends of the above resins There is no problem if the resin can be processed by a molding machine.

The wire diameter of the three-dimensional network structure is as follows.
0.1 to 5.0 mm, preferably about 0.3 to 2.0 mm, has good moldability, and the larger the strand diameter, the better the pressure resistance. As another method for improving the pressure resistance, a thermoplastic resin having a relatively large flexural modulus may be used, or an inorganic filler may be used in combination. On the contrary, in order to obtain a soft three-dimensional net-like structure having a good cushioning property, it is preferable to reduce the strand diameter or to use a thermoplastic resin such as an elastomer having a small bending elastic modulus.

[0016]

FIG. 1 is a sectional view of a typical apparatus for manufacturing a three-dimensional net-like structure according to the present invention. Embodiments of the present invention will be described based on the following examples.

[0017]

EXAMPLE In Example 1, the screw diameter was 90 m.
A single screw extruder having a diameter of 1.0 m × 50 mm and a die 2 having nozzles 0.8 having a diameter of 0.8 mm and approximately 800 at substantially equal intervals were attached to the single screw extruder. A cooling water tank 6 having a water level at a position of about 120 mm below the nozzle 4 is installed, and a pair of 1.2 m wide belt conveyors 1 are spaced apart by 25 mm so that the upper part of the belt conveyor 1 comes out of the water surface by about 40 mm. It was installed almost vertically.

With this apparatus, the EVA resin is heated and plasticized by applying heat to the die 2 so that the resin temperature becomes 240 ° C.
The molten resin bundle 5 discharged from the nozzle 4 was extruded between the pair of belt conveyors 1 at an extrusion rate of 120 kg per hour such that both surfaces of the bundle 5 dropped on the belt conveyor 1. At this time, the take-up speed of the belt conveyor 1 was 0.7 m / min. The molded product that has been moved downward by being sandwiched between the belt conveyors 1 changes its direction at the lower part of the cooling water tank 6 and moves to the water surface from the side opposite to the extruder. Water was blown away.

The three-dimensional network structure 3 thus obtained
Has a width of 1.0 m, a thickness of 25 mm, and a strand diameter of 1.0 m.
m, porosity at center is about 96%, 2.0 mm from surface
The porosity of both surface portions up to about 70%.

In Example 2, the screw diameter is 90
A single-screw extruder having a diameter of 1.0 mm and an area of 1.0 mm × 30 mm were provided with approximately 500 dies having nozzles having a diameter of 0.5 mm at substantially equal intervals. A water tank having a water level is installed at a position of about 150 mm below the nozzle, and a pair of 1.2 m wide belt conveyors are arranged at intervals of 20 mm.
It was installed almost vertically so as to come out of the water surface by about 0 mm.

While plasticizing the polypropylene resin by applying heat, the temperature of the die was controlled so that the resin temperature reached 260 ° C., and the belt conveyor was shifted from the nozzle at an extrusion rate of 100 kg per hour by shifting the position of the belt conveyor. It was extruded between a pair of belt conveyors such that only one side of the resin bundle fell onto the belt conveyor. The take-up speed of the belt conveyor at this time was 1.0 m / min. The molded product, which was moved downward by being sandwiched by the belt conveyor, changed its direction at the lower part of the water tank, moved to the water surface from the side opposite to the extruder, and when it came out of the water tank, the moisture was removed by a vacuum pump.

The three-dimensional network structure 3 thus obtained
Has a width of 1.0 m, a thickness of 20 mm, and a wire diameter of 0.7 mm.
The porosity of the central portion was around 94%, and the porosity of the one-side surface portion from the surface having the higher density to 1.5 mm was around 50%.

[0023]

The three-dimensional network structure obtained in Example 1 is
When used as a drainage material on the back side of the retaining wall, the density of the surface is high, so it is difficult for soil particles to enter inside, and the porosity of the central part is high, so the water collected in the drainage material flows smoothly inside, It was confirmed that a good drainage function was exhibited.

The three-dimensional network structure obtained in Example 2 was used as a substrate for greening the slope. First, fix the three-dimensional network structure on the slope to be greened with pins so that the side with the low porosity is on the side of the slope, and mix soil, water, fertilizer, seeds, aggregates, etc. from above, The slurry was sprayed by the thickness of the three-dimensional network structure.

Since the porosity of the sprayed surface of the three-dimensional network structure is high, the sprayed mixture easily entered the inside of the three-dimensional network structure, was not entangled, and did not flow down. In addition, the low-porosity surface of the three-dimensional network structure with a low porosity is fixed to the slope with a pin, and the density is high and the tensile strength is strong, so the three-dimensional network structure may be damaged by the load of the sprayed earth and sand. There was no.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a typical apparatus for manufacturing a three-dimensional network structure of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Belt conveyor 2 Dice 3 Solid net structure 4 Nozzle 5 Molten resin 6 Cooling water tank

Claims (3)

[Claims] In a flat three-dimensional net-like structure to which a random spiral linear thermoplastic resin is point-adhered, from the surface in the thickness direction, 1 to 3 times the element wire diameter of the linear thermoplastic resin. A porosity of a surface portion on both surfaces or one surface up to a distance of less than a porosity of a central portion excluding the surface portion. 2. The porosity at the center is 85% or more and 98% or less, and the porosity at both surfaces or one surface is 10% or more.
The three-dimensional network structure according to claim 1, which is 0% or less. 3. A three-dimensional net-like structure is produced by extruding a molten thermoplastic resin downward from a plurality of nozzles, allowing the molten thermoplastic resin to naturally descend between a pair of partially conveyed belt conveyors, and taking it down at a speed lower than the descending speed. At this time, the interval between the pair of belt conveyors is narrower than the width of the extruded molten resin bundle, and both or one surface of the molten resin bundle is in contact with the belt conveyor before the belt conveyor is submerged. A method for producing a three-dimensional network structure characterized by the following.