JP2002332630A - Drain material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drain material finely collecting redundant water in the ground, having permeability capable of effectively discharging the redundant water specially even under high compressive load, preventing soil particles from being finely filled even if the soil particles and the redundant water suddenly enter therein, difficult to get clogged, rich in high resistance to pressure, firmness and durability and having light and good workability. SOLUTION: The drain material has filter layers to which a web consisting of a heat adhesive composite fiber is thermally welded, the filter layers comprise three layers having consecutive void content slopes, the first filter layer corresponding to an outside layer and the third filter layer corresponding to an inside layer are the layers having the void content slopes with the consecutively low void content in the direction of the thickness, the second filter layer corresponding to an intermediate layer is the layer having a certain void content in the direction of the thickness, and the drain material has the filter layers laminated in order of the first filter layer/the second filter layer/the third filter layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous drain material for discharging surplus water in soil or artificial ground to stabilize the ground.

[0002]

2. Description of the Related Art Conventionally, a porous drain material has been used as a drain material for discharging excess water from the ground and stabilizing the ground. Above all, a porous drain material having a filtration layer in which a web made of a heat-adhesive conjugate fiber is heat-sealed is lightweight and easy to construct, and can prevent deformation and cracking of the drain material after being buried in soil, Furthermore, it is widely used because clogging can be prevented relatively well. For example, Japanese Patent Application Laid-Open No. Hei 8-266149 discloses that the single yarn fineness is 5 to 1%.
A porous drain material obtained by winding a 500-denier heat-fusible composite fiber web around an iron core while heating is disclosed. However, since the drain material has a simple structure in which the porosity continuously decreases from the outside to the inside of the drain material, when the soil particles and water suddenly enter the drain material. However, there is a drawback that the drain material is densely packed with soil particles, the drainage property is reduced, and the function as the drain material is reduced, and there is still room for improvement.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to collect excess water in the ground satisfactorily and to effectively discharge the excess water. It does not cause soil particles to be densely packed even if there is a sudden intrusion of soil particles and surplus water. And to provide a drain material having good workability.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems. As a result, it was found that the intended purpose was achieved by employing the following configuration, and the present invention was completed based on this finding. That is, the present invention has the following configuration. (1) A drain material having a filtration layer to which a web made of a heat-adhesive conjugate fiber is heat-sealed, wherein the filtration layer is composed of three continuous porosity gradients, and a first filtration layer corresponding to an outer layer And the third filtration layer corresponding to the inner layer is a layer having a porosity gradient in which the porosity continuously decreases in the thickness direction,
The second filtration layer corresponding to the intermediate layer is a layer having a constant porosity in the thickness direction, and the first filtration layer / the second filtration layer / the third filtration layer.
A drain material having a filtration layer laminated in the order of a filtration layer. (2) The drain material according to the above (1), wherein the drain material is a cylinder formed by winding a web made of a heat-adhesive conjugate fiber. (3) The fineness of the heat-adhesive conjugate fiber is 10 to 100 dte
The drain material according to the above (1) or (2), wherein x is x. (4) The heat-adhesive conjugate fiber according to (1) to (3), wherein the heat-adhesive conjugate fiber is a heat-adhesive conjugate fiber composed of a low-melting resin having a melting point difference of 10 ° C. or more and a high-melting resin. The drain material according to claim 1.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The drain material of the present invention is a drain material having a filter layer to which a web made of a heat-adhesive conjugate fiber is heat-sealed, wherein the filter layer of the drain material has a porosity gradient. The first filtration layer corresponding to the outer layer and the third filtration layer corresponding to the inner layer are layers having a porosity gradient in which the porosity continuously decreases in the thickness direction. The second filtration layer corresponding to the layer is a layer having a constant porosity in the thickness direction, and has a filtration layer laminated in the order of first filtration layer / second filtration layer / third filtration layer. . When the third filtration layer is clogged by soil particles,
It will not function as a drain material. The second filtration layer may be composed of a plurality of layers as long as the filtration life and the pressure resistance of the drain material are not reduced.
Note that the outer layer refers to a layer on the front surface side of the drain material when buried in soil, and the inner layer refers to a layer on the back surface side or inside of the drain material.

The heat-adhesive conjugate fiber used in the present invention is:
Composite fibers composed of two or more kinds of thermoplastic resins having a difference in melting point are used. In particular, a heat-adhesive conjugate fiber composed of a low melting point resin and a high melting point resin having a melting point difference of 10 ° C. or more is preferable, and the melting point difference is more preferably 15 ° C. or more. In addition, it is preferable that the low melting point resin constituting the conjugate fiber is exposed on the fiber surface and is continuous in the longitudinal direction from the viewpoint of thermal adhesiveness.

As the low-melting resin and the high-melting resin constituting the heat-adhesive conjugate fiber, a crystalline thermoplastic resin is used. Specifically, high-density polyethylene, low-density polyethylene, and polyethylene such as linear low-density polyethylene, ethylene-propylene binary copolymer, ethylene-
Propylene such as propylene-butene-1 terpolymer
Examples thereof include thermoplastic resins such as α-olefin copolymer, polypropylene, polyethylene terephthalate, and polyamide. These thermoplastic resins may be used alone or in combination of two or more.

The combination of the low melting point resin and the high melting point resin is, for example, expressed as low melting point resin / high melting point resin.
High-density polyethylene / polypropylene, linear low-density polyethylene / polypropylene, low-density polyethylene / polypropylene, binary or terpolymer of propylene and other α-olefins / polypropylene, linear low-density polyethylene / High density polyethylene, low density polyethylene / high density polyethylene, various polyethylenes /
Polyethylene terephthalate, polypropylene / polyethylene terephthalate, binary or terpolymer of propylene and other α-olefin / polyethylene terephthalate, low melting thermoplastic polyester / polyethylene terephthalate, various polyethylene / nylon 6, polypropylene / Nylon 6, propylene and other α
-Binary copolymers with olefins or ternary copolymers / Nylon 6, Nylon 6 / Nylon 66, Nylon 6 / Thermoplastic polyester, and any combination selected therefrom.

Of these, combinations of polyolefins or a combination of polyolefin and polyester are preferred. For example, low density polyethylene / polypropylene, linear low density polyethylene / polypropylene, high density polyethylene / polypropylene, ethylene-propylene-butene-1 Ternary copolymer / polypropylene, ethylene-propylene binary copolymer / polypropylene, ethylene-propylene-butene-1 terpolymer / polyethylene terephthalate, or high-density polyethylene / polyethylene terephthalate Combinations can be mentioned. Among them, combinations of polyolefins, such as high-density polyethylene / polypropylene, ethylene-propylene-butene-1 terpolymer / polypropylene, and ethylene-propylene binary copolymer / polypropylene, from the viewpoint of chemical resistance and light weight. Is particularly preferred.

Examples of the composite form of the heat-adhesive composite fiber include concentric sheath core type, eccentric sheath core type, side-by-side type, sea-island type and hollow type. In view of the thermal adhesive property, a composite fiber having a concentric sheath-core type, an eccentric sheath-core type, and a parallel type structure is preferably used. Above all, a heat-adhesive conjugate fiber having a concentric sheath-core structure has a stable heat-adhesive property and is preferable. When the conjugate fiber is a conjugate fiber composed of two components, a low-melting resin and a high-melting resin, the conjugate ratio is determined by considering the weight ratio of the low-melting resin: the weight ratio of the high-melting resin in consideration of thermal bonding performance. It is preferred to be in the range of 30:30 to 70:30. When the weight ratio of the low-melting resin is significantly lower than 30, the adhesiveness is significantly reduced. Conversely, when the weight ratio of the low-melting resin is significantly higher than 70, the low-melting resin in the heat-bonded portion between the fibers. The components are spread to form a film, and the gaps are closed, so that drain performance tends to decrease.
When the composite fiber is composed of three or more components, it is preferable that the weight ratio of the resin that can be an adhesive component does not fall significantly below 30 in the composite ratio.

The fineness of the heat-adhesive conjugate fiber used in the present invention may be determined according to the use of the drain material, but is preferably from 10 to 100 dtex. Fineness is 10 dt
If the value of ex is significantly lower than the value of ex, the mesh composed of the fibers of the obtained drain material becomes very fine and minute, so that earth and sand are easily clogged and long-term use is difficult. Conversely, if the fineness of the thermoplastic fiber greatly exceeds 100 dtex, the rigidity of the fiber becomes too high and it is difficult to consolidate,
It becomes difficult to obtain a molded product having a sufficient porosity with sufficient pressure resistance. For these reasons, the preferred fineness range is from 20 to 9
0 dtex, and a more preferable fineness range is 50 to
80 dtex.

The number of crimps of the heat-adhesive conjugate fiber used in the present invention may be determined in accordance with the specifications of the apparatus for forming the web and the required specifications of the drain material. 5 to 30 peaks per inch. When the number of crimps is significantly less than 5 peaks / 25 mm, not only does the entanglement between the fibers decrease, so that the moldability of the web tends to deteriorate, but also the mesh-like gap of the drain material composed of the fibers increases. Tends to be too much. Conversely, if the number of crimps greatly exceeds 30 peaks / 25 mm, the repulsion between the fibers during the formation of the drain material becomes too strong, making it difficult to consolidate, and the moldability tends to decrease. More preferred number of crimps is 6 to 2
0 peaks / 25 mm, and an even more preferred number of crimps is 7
１５15 peaks / 25 mm. The type of crimp used in the heat-adhesive conjugate fiber of the present invention is not limited, and various crimp forms such as mechanical crimp and spiral crimp can be used.

The heat-adhesive conjugate fiber used in the present invention is:
It is possible to use it as a web in the form of continuous filaments of continuous fibers, or to cut it to an arbitrary length and use it as a web in the form of staple fibers. This is preferable from the viewpoint of the uniformity of the entanglement between them. When used as a staple fiber, the cut length is not particularly limited, but is preferably in the range of 16 to 256 mm, more preferably in the range of 32 to 156 mm. The most preferred staple fiber cut length is 64 to 12
8 mm.

The form of the web composed of the heat-adhesive conjugate fiber is not particularly limited, and the staple fiber can be used as a web such as a parallel web, a random web, and a cross web. The basis weight of the web is not particularly limited, 10 to 200 g / cm ² can be used preferably, can be used more preferably the basis weight of 30 to 80 g / cm ^2. If the basis weight exceeds 200 g / cm ² , the web becomes bulky, and it tends to be difficult to obtain a uniform porosity gradient during processing into a drain material. In the present invention, not only one layer but also a multi-layered web may be used. In the case of laminating in multiple layers, the laying method is such that the fiber directions of the upper layer side and the lower layer side are parallel to each other, the cross laying method in which the fiber directions are perpendicular to each other, Various methods can be used, such as a laying method at an arbitrary angle. The web may be mixed with other thermoplastic fibers or natural fibers to the extent that the effects of the present invention are not impaired. Further, in order to add a function to the drain material, webs made of different types of fibers may be laminated, or webs made of different fineness may be laminated. Also, a process such as a method of stretching the web to increase the strength of the web or a method of strengthening the entanglement between fibers by needling treatment may be combined.

The heat-adhesive conjugate fiber used in the present invention may contain an additive in the raw material thermoplastic resin at the time of production as long as the effects of the present invention are not impaired. Examples of the additive include a colorant, a flame retardant, an antibacterial agent, and a stabilizer. The amount of these additives is appropriately selected depending on the type of the thermoplastic resin constituting the composite fiber, the use, the use place, and the use environment of the present invention.

In order to produce the drain material of the present invention,
Various manufacturing methods can be used depending on the form and shape of the intended drain material, but the shape of the drain material is preferably a tubular shape formed by winding a web made of a heat-adhesive conjugate fiber, A cylindrical shape is particularly preferable in terms of productivity and production cost.

As the cylindrical drain material, for example, a web is produced by a card machine, conveyed by a conveyor, and further subjected to a heat treatment of the web by a through-air heater to form a low-adhesive composite fiber in the web. Softens the melting point component,
In a molten state, the web can be produced by winding the web around an iron core supported by columns on a conveyor belt.
The support supporting the center may be lifted by hydraulic pressure or the like as necessary to adjust the linear pressure applied to the web. At this time, not only in the web but also in the interlayer of the web, the form of the drain material is stabilized. Specifically, first, the web is heat-treated, and is continuously wound around an iron core on a conveyor belt. At this time, since the pressed web is further applied to the web by the wound web, a filtration layer having a porosity gradient is formed. By winding the web until the desired thickness is reached, a third filtration layer can be formed. Next, at the same time when the desired thickness is reached, the iron core is raised to reduce the linear pressure, and the second filtration layer is formed. At this time, compared with the porosity immediately before changing the linear pressure, a filtration layer having a high porosity is temporarily formed, but by continuing to wind the web, the thickness of the filtration layer increases,
The porosity is equal to or close to the value before the change of the linear pressure. In order to prevent the porosity from being largely changed by further increasing the thickness, the same linear pressure change can be repeated several times to form a second filtration layer having substantially the same porosity. When the iron core is further raised to lower the linear pressure and the winding is advanced, a layer is formed in which the porosity gradually increases as the outer diameter increases, and this is the first filtration layer. Becomes In this way, the drain material is wound up to a required thickness, and after cooling the drain material, the iron core is removed from the drain material, and shaping such as cutting off unnecessary ends is performed. Trim to length. Thereby, a cylindrical drain material can be obtained. In addition, as a method of the heat treatment performed here, for example, in addition to a through-air heater, a hot-air circulation heater, an infrared heater, a far-infrared heater, a high-pressure steam heater, an ultrasonic heater, and a hot roll heater , Thermocompression roll type heating machine,
A heat treatment method using an oven or the like can be given. Further, these devices may be used alone or in combination.

By adjusting the linear pressure applied to the web during winding as described above, the porosity can be changed. The porosity of the entire drain material after winding is 60
Preferably, the porosity is 68 to 78%, more preferably 68 to 78%. When the porosity exceeds 85%, it is difficult to maintain the shape as a drain material, and the pressure resistance becomes poor. On the other hand, when the porosity is significantly lower than 60%, the drainage tends to decrease because the porosity is too low. In addition, the filtration life as a drain material tends to be extremely short. When a porosity gradient is provided, the porosity of the first filtration layer corresponding to the outer layer is in the range of 90 to 65%, and the porosity of the third filtration layer corresponding to the inner layer is in the range of 80 to 55%. The porosity of the second filtration layer corresponding to the intermediate layer sandwiched between the first filtration layer and the third filtration layer is substantially constant in the range of 87 to 58% from the first filtration layer to the third filtration layer. It is preferable that the value be as follows. The porosity difference between the first filtration layer and the second filtration layer or between the second filtration layer and the third filtration layer is preferably 10% or less. If this range is significantly exceeded, the drain material tends to be finely packed due to abrupt intrusion of soil particles into the drain material, and delamination tends to occur easily.

The porosity of the entire drain material can be obtained from its volume and weight, and the porosity of each filtration layer is measured by separating each filtration layer from the drain material and using a measuring method suitable for each layer state. be able to. In addition, since the second filtration layer needs to have a constant porosity in the thickness direction, the second filtration layer is divided into two, and the porosity of each of the divided filtration layers is measured to be substantially equal. It is desirable to confirm that. However, the first filtration layer and the third filtration layer
Since the porosity has a porosity gradient in which the porosity continuously decreases in the thickness direction, the porosity obtained from the volume and the weight is the average porosity. The difference in porosity from the layer is unclear. Therefore, if possible, the first filtration layer and the third filtration layer are divided into at least three, and the porosity of each of the divided filtration layers is measured.
The measured data of the porosity on the side in contact with the filtration layer and the porosity of the second filtration layer are graphed and judged from the obtained porosity gradient line. However, when the filtration layer is thin and cannot be divided into two or more, the first filtration layer, the second filtration layer, and the third filtration layer
Graphing can be performed only at points, and it is often difficult to determine the presence or absence of a porosity gradient from the obtained porosity gradient line. In such a case, the particle size distribution of the drain material may be measured using a standard sample, the measured data may be graphed, and the determination may be made from the particle size distribution (density gradient line). In addition, even when the first filtration layer and the third filtration layer can be divided and their porosity can be measured, the particle size distribution of the drain material is measured, the measured data is graphed, and the particle size distribution ( It is preferable to judge from the density gradient line).

The porosity difference between the filtration layers may be obtained by calculating the porosity of each filtration layer and approximating the difference as a porosity gradient. The porosity of two portions of the divided layer including the portion exposed on the surface of the first filtration layer and the divided layer including the portion in contact with the second filtration layer is obtained, and the difference between the porosity of the two portions is calculated from the porosity. You can ask. The same can be obtained for the third filtration layer. In addition, since the thickness of the drain material of the present invention is not particularly limited, there may be a drain material having a filtration layer having a thickness that is too small to be divided depending on the shape and the application. In such a case, the difference in porosity between the first or third filtration layer and the second filtration layer was defined as the porosity difference between the layers. For example, the porosity of the first filtration layer is 80%,
If the porosity of the second filtration layer is 78%, the porosity difference is 2%.
Becomes

The function of the drain material of the present invention will be described in a state where it is buried in soil. Excess water containing earth and sand (soil particles) flows from the outer layer (first filtration layer) of the drain material into the drain material, and moves further inside. At this time, the soil particles having a large particle diameter are collected near the surface, and move into the filtration layer as the particle diameter decreases. At this time, the inflowing soil particles are collected by the mesh portion formed by the heat-adhesive conjugate fibers, and thus provide pressure resistance to the first filtration layer.
Furthermore, the trapped soil particles form a water supply (water path) therebetween, thereby maintaining water permeability. The collected particles such as silt and clay may be aggregated to generate pseudo-large particles. Next, small to medium-sized soil particles that have passed through the first filtration layer, pseudo-large particles generated in the first filtration layer are broken down into fine particles, and organic matter such as collected plants is spoiled. The fine particles and the like move to the second filtration layer having an appropriate thickness and porosity. The second filtration layer has a narrow distribution of the collected soil particle diameter. That is,
When the depth of the second filtration layer in the thickness direction is plotted on the X axis and the particle size of the collected soil particles is plotted on the Y axis, the graph becomes X
It becomes a straight line almost parallel to the axis. Here, the term “parallel” refers to a state where the inclination of the straight line is small. This second filtration layer functions as a buffer that prevents dense packing due to a rapid inflow of soil particles. In addition, soil particles, pseudo-large particle collapse particles, organic flake particles, and the like, collected between the meshes formed by bonding the intersections of the heat-adhesive conjugate fibers with the cushioning material are further reduced by flowing water pressure and frictional force. By being crushed, it is discharged to the third inner filtration layer.

The role of each filtration layer in the drain material of the present invention will be described in detail. The first filtration layer has a porosity gradient in which the porosity continuously decreases, thereby functioning as a prefilter for large-particle-size soil.

As described above, the second filtration layer functions as a cushioning material for preventing fine packing due to a sudden inflow of soil particles. The function of the buffer material is exhibited when the second filtration layer has an appropriate thickness and the porosity is substantially constant. In particular, the thickness of the second filtration layer plays a very important role. For example, when the thickness is very small, such as filter paper, spunbonded nonwoven fabric, and meltblown nonwoven fabric, the density of particles in the thickness direction increases. When the density is further increased, the density of the particles in the plane direction is also increased, so that clogging is easily caused. In order to prevent this, it is effective to provide the filtration layer with a certain thickness. That is, if the density of the particles in the thickness direction does not increase,
It should be possible to suppress the density of particles in the plane direction, and it is estimated that clogging is unlikely to occur. The thickness of the second filtration layer is preferably 5 mm or more, though it depends on the configuration of the soil. Note that the second filtration layer also functions as a filter for soil having a small to medium particle size (soil particles).

Since the third filtration layer has the same structure as the first filtration layer, the function is basically similar to that of the first filtration layer. However, since the porosity is the lowest in the drain material, the pressure resistance of the drain material is reduced. Functions as a reinforcing material (core material). Further, when the soil particles discharged from the drain material are too large or the discharging speed of the soil particles is too high, the third filtration layer may cause sediment or sediment to block a drainage system such as a drainage pit. Therefore, it has a function as a filter that collects only soil particles of a certain size or more. Further, the third filtration layer has a function of preventing the accumulation of the discharged particles by reducing the size of these soil particles to a fine particle size that does not easily block the drainage system. The third filtration layer holds the soil particles in the drain material to such an extent that the drain material does not block, and can discharge over time while sequentially reducing the size of the particles. Usually, the filter material is used for the purpose of filtration, while the drain material is used for the purpose of drainage.

The drain material of the present invention may have a mat shape. Hereinafter, a method for producing a mat-shaped drain material will be described. The third filtration layer and the first filtration layer can be manufactured by scattering the staple fiber in the air, sucking the staple fiber, depositing the staple fiber on the conveyor so as to have a porosity gradient, and further thermally bonding the staple fiber. . In addition, the staple fiber is scattered in the air, deposited on a conveyor without suction, and then thermally bonded to form a second staple fiber.
A filtration layer can be manufactured. Each obtained filtration layer is a first filtration layer,
The drain material of the present invention can be manufactured by laminating and integrating the second filtration layer and the third filtration layer in this order. At this time, the first filtration layer and the third filtration layer are sandwiched by the second filtration layer. It is necessary to adjust the porosity to be continuous, and a mat-shaped drain material can be obtained by further bonding the thus adjusted three-layer mat by heat (compression bonding). Also, as another manufacturing method, for example, a drain material formed into a cylindrical shape is cut open in the length direction of the drain material,
Further, this is heated and press-formed in a softened state, so that a mat-shaped drain material can be obtained.

Examples of the construction method using the drain material of the present invention include a construction method of embedding or placing the drain material of the present invention in soil or artificial ground. By this construction, it becomes possible to discharge surplus water in the soil or artificial ground. The direction in which the drain material is buried is not particularly specified, and the drain material can be installed in any direction with respect to the ground.

Since the drain material of the present invention has excellent properties such as pressure resistance and drainage function, it can be used not only for stabilization of soil in mountains and valleys, but also for roadbed foundations associated with railway track facilities, general roads and roads. It can be used to stabilize various soils such as subgrade foundations, road facilities, airport facilities, harbor facilities, landfills, baseball stadiums and soccer fields, which are associated with road facilities such as high-standard roads.

The drain material of the present invention can be used not only for discharging liquid such as surplus water but also for discharging gas, so that it can be used as a degassing material. For example, by vertically driving the drain material of the present invention into a landfill containing garbage or a layer containing natural gas, gas can be discharged from these layers. In addition, by vertically implanting the drain material of the present invention near the root of a tree, exchange of oxygen and carbon dioxide in soil can be smoothly performed, and growth can be activated.

The drain material of the present invention can be used not only alone but also in combination with other materials such as fabrics, films, metal nets, construction materials, civil engineering materials and agricultural materials.

[0030]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Hereinafter, the measurement and evaluation methods used for the drain material of the present invention will be described. (1) Pressure resistance performance Evaluation was performed using "Autograph AGS-500D type tensile compression tester" manufactured by Shimadzu Corporation. A compression plate having a size of 250 mm × 300 mm was set in the tensile compression tester, and a drain material sample having a length of 250 mm was fed at a speed of 30 m.
Compressed at m / min. The measurement is performed until the pressure strength peak temporarily decreases, and then the maximum strength (yield point strength)
Is the pressure resistance.

(2) Porosity The porosity was determined by the following equation. Porosity (%) = [1- (weight) g ÷ ｛(volume) cm ³ ×
(Fiber specific gravity) g / cm ³ ｝] × 100

(3) Porosity difference The drain material was divided into a first filtration layer, a second filtration layer, and a third filtration layer, and the porosity of each was determined, and the difference was calculated.
If the boundary position of each layer cannot be visually distinguished, a particle size distribution measurement in the thickness direction is performed in advance, the thickness of each layer is determined from the obtained particle size distribution map, and an unused drain material similarly manufactured. Using the sample, each was divided into layers, and the porosity difference was calculated. Porosity difference Δv ₁₂ = (porosity of first filtration layer) − (porosity of second filtration layer) Porosity difference Δv ₂₃ = (porosity of second filtration layer) − (porosity of third filtration layer) When the first and third filtration layers are sufficiently thick even if they are single layers, each of the filtration layers is preferably divided into three or more layers, and the uppermost layer and the lowermost layer of the divided filtration layers are separated. The porosity of the position layer is determined, and the difference can be calculated by the following equation. Porosity difference Δv _TB = (porosity of uppermost layer) − (porosity of lowermost layer)

(4) Measurement of Particle Size Distribution (Thickness Direction) A method of measuring the particle size distribution of the drain material sample in the thickness direction will be described with reference to FIGS. A cylindrical drain material sample B in which one end surface in the length direction is closed with a film G on a wall surface of an apparatus container H (width 400 x depth 550 x height 325 mm).
Is fixed with a joint C, water is supplied to the earth and sand E at a flow rate of 60 (liter / min) from a top surface of the apparatus container by a hose F, and the earth and sand E and the water are stirred to generate turbid water. From drain material sample B to PVC pipe D
And drained from the PVC pipe D. At this time, the head height was always generated. This drain material sample B
Is 250 mm, but the effective filtration length is 150 mm because of the joint C and the film blockage. The sediment deposited on the drain material sample was shaken down every 30 minutes so as not to hinder the inflow of sediment. Water was supplied for a total of 40 hours. As the soil, the trade name “Shiba no Mado” (Create Sumi Waka; particle size 1-2 mm center), the trade name “Horticultural soil” (Tachikawa Heiwa Farm, organic soil), and Sakurajima volcanic ash ( Use 4 liters of mixed soil with Kyushu Expressway SA; silt and clay) and the mixing ratio (volume ratio) is sand: horticultural soil: volcanic ash = 16: 3:
It was set to 1. In addition, although the classification | category by the particle size of a soil particle has a slight difference with the soil classification method, in general, the particle size is 5-5.
The soil particles of 0 μm are classified as silt, and the finer soil particles of 5 μm or less are classified as clay. Here, there is no particular intention of quantitatively configuring the mixed soil, and a mixed soil having a wide range of particle diameters may be used in the test. The drain material sample thus obtained was divided into seven parts in the thickness direction, and photographed at a magnification of 50 times using a microscope from the surface side (high porosity direction side) of each piece (the drain material of the present invention was used). In the case of a cylindrical shape, the outer peripheral direction is the surface, and in the case of the plate shape, the layer having a high porosity is the surface. Ten pieces of earth and sand particles were arbitrarily selected from the photographed photographs, the particle diameter of each particle was measured with calipers, the root-mean-square value of the measured value was calculated, and the actual value was calculated from the enlarged scale. Further, the average of the obtained actual values was determined, and this was defined as the average particle diameter, and the relationship between the average particle diameter and the depth was plotted.

(5) Drainage test 0.2 m wide, 0.2 m deep and 4.2 m long on the ground
The pit was dug, and a drain material sample was installed at a gradient of 3%, and then backfilled with the original earth and sand. The lower end of the drain material sample was connected to a catchment basin where the drainage could be observed. 400 liters of water were sprayed once a month, and the state of drainage to the catchment basin and the state of drainage on the ground surface were observed. The observation was performed for one year.

Example 1 Heat-adhesive conjugate fiber (high-density polyethylene having a sheath component of a melting point of 130 ° C., polypropylene having a core component of a melting point of 163 ° C., a component weight ratio of the sheath core of 50:50, and a number of crimps of 10 peaks / 25 m)
m, a cut length of 89 mm, and a single fiber fineness of 72 dtex) to form a card web, cross-lay it into four layers to obtain a web having a basis weight of 48 g / m ² , and then use a through-air heater set at 143 ° C. While heating, it is wound on an iron core with a diameter of 76 mm on a conveyor belt,
A filtration layer was prepared in the order of the third filtration layer / the second filtration layer / the first filtration layer, and was used as a drain material. At this time, 0.12 MPa
(1.2 kgf / cm ² ; hereinafter, 1 kgf / cm ² = 0.
An iron core was supported by a support at a pressure of 1 MPa (approximately 1 MPa), and a third filtration layer was formed while applying a linear pressure to the web by the load of the core and the wound web. After the thickness of the third filtration layer was reduced to about 1/3 of the target, the core was supported by a column at a pressure of 0.16 MPa (1.6 kgf / cm ² ) while being wound up (the core was lifted). A second filtration layer was formed. After the thickness of the second filtration layer becomes about 2/3 of the target, while the film is further wound up, it is cooled to 0.18 MPa (1.
At a pressure of 8 kgf / cm ² ), the core was supported by columns (the core was lifted) to form a first filtration layer. The web was wound up until the drain material became a specified size, and after cooling the drain material, the core was taken out, and both ends were cut off and shaped to obtain a drain material. This hollow cylindrical drain material has an outer diameter of 114 mm, a wall thickness of 19 mm, and a weight of 229.
6 g / (2 m), and the total porosity was 78.0%.
Also, 12680 N / m (1268 kgf / m; 1 kg
f = 10N). Further, when a particle size distribution measurement in the thickness direction of the drain material was performed, a composite filtration layer in which the first filtration layer 1 / the second filtration layer 2 / the third filtration layer 3 were connected as shown in FIG. 2A was confirmed. did it. The first
The filtration layer and the third filtration layer had a porosity gradient, and the porosity gradient was hardly recognized in the second filtration layer. Also,
When the porosity difference between the respective layers was calculated, Δv ₁₂ was 2.4.
% And Δv ₂₃ were 1.2%. In addition, a drainage test of the drain material was performed, and it was confirmed that drainage to the catchment basin was good one year later, and the ground surface was well drained along with watering (see Table 1). Therefore, it was found that the obtained drain material had excellent pressure resistance and drainage performance.

Example 2 Heat-adhesive conjugate fiber (high-density polyethylene having a sheath component of melting point of 126 ° C., polyester having a core component of melting point of 256 ° C., sheath-core component weight ratio of 60:40, crimp number: 15 ridges / 25 mm) ,
A card web was formed using a cut length of 128 mm and a single yarn fineness of 100 dtex), and this was cross-laid into six layers to obtain a web having a basis weight of 62 g / m ² , and then heated with a through-air heater set at 150 ° C. While winding on a steel core with a diameter of 76 mm on a conveyor belt,
A filtration layer was prepared in the order of the third filtration layer / the second filtration layer / the first filtration layer, and was used as a drain material. At this time, 0.12 MPa
A third filtration layer was formed while supporting the iron core with a support at a pressure of (1.2 kgf / cm ² ) and applying linear pressure to the web by the load of the core and the wound web. After the thickness of the third filtration layer is reduced to about 1/3 of the intended thickness, the core is supported by a support at a pressure of 0.18 MPa (1.8 kgf / cm ² ) while being wound up to form a second filtration layer. I let it. This second
After the thickness of the filtration layer becomes about 2/3 of the target, 0.20 MPa (2.0 kgf / cm ² )
The first core was supported by the support at the pressure described above to form the first filtration layer.
The drain material was wound up to a specified size, and after cooling the drain material, the core was taken out, and both ends were cut off to obtain a drain material. This hollow cylindrical drain material has an outer diameter of 116 mm, a wall thickness of 20 mm, and a weight of 256.
1 g / (2 m), and the total porosity was 76.9%.
Further, 13442 N / m (1344 kgf / m; 1 kg
f = 10N). Further, when the particle size distribution of the drain material in the thickness direction was measured, the first filtration layer 1 / the second filtration layer 2 / the third filtration layer having the same shape as 2B in FIG.
A composite filtration layer in which the filtration layers 3 were connected was confirmed. Note that the first filtration layer and the third filtration layer have a porosity gradient,
The second filtration layer showed almost no porosity gradient. When the porosity difference between the respective layers was calculated, Δv ₁₂ was 2.
7% and Δv ₂₃ were 1.0%. In addition, a drainage test of the drain material was performed, and it was confirmed that drainage to the catchment basin was good one year later, and the ground surface was well drained along with watering (see Table 1). Therefore, it was found that the obtained drain material had excellent pressure resistance and drainage performance.

Example 3 Thermoadhesive conjugate fiber (ethylene-sheath component having a melting point of 143 ° C.)
Propylene-butene-1 terpolymer, core component having a melting point of 1
Polypropylene at 64 ° C., the component weight ratio of the sheath core is 50: 5
0, 8 crimps / 25 mm, cut length 64 mm, single yarn fineness 18 dtex) to obtain a card web.
The layer was cross-laid to give a web with a basis weight of 51 g / m ² , and the web was heated with a through-air heater set at 153 ° C. while a diameter of 114 m on a conveyor belt.
The filter layer was wound around an iron core of m, and a filtration layer was formed in the order of a third filtration layer, a second filtration layer, and a first filtration layer, and was used as a drain material. At this time, the iron core was supported at a pressure of 0.14 MPa (1.4 kgf / cm ² ), and a third filtration layer was formed while applying a linear pressure to the web by the load of the core and the wound web. After the thickness of the third filtration layer is reduced to about 1/3 of the target, while the film is being wound up, it is cooled to 0.16 MPa (1.6 kgf /
The core was supported by columns at a pressure of ² cm ² ) to form a second filtration layer. After the thickness of the second filtration layer was reduced to about ／ of the target, while the film was further wound up, the thickness was reduced to 0.20 MPa (2.0
The core was supported by a column at a pressure of kgf / cm ² ) to form a first filtration layer. The drain material was wound up to a specified size, and after cooling the drain material, the core was taken out, and both ends were cut off to obtain a drain material. This hollow cylindrical drain material has an outer diameter of 166 mm and a thickness of 26 m.
m, weight 4229 g / (2 m), total porosity 7
9.9%. In addition, 10986 N / m (1099
kgf / m; approx. 1 kgf = 10 N). Further, when the particle size distribution of the drain material in the thickness direction was measured, the first filtration layer 1/1 having the same shape as 2C in FIG.
A composite filtration layer in which the second filtration layer 2 / the third filtration layer 3 were connected was confirmed. In addition, the 1st filtration layer and the 3rd filtration layer have a porosity gradient, and the porosity gradient was hardly recognized in the 2nd filtration layer. When the porosity difference between the respective layers was calculated, Δv ₁₂ was 3.3% and Δv ₂₃ was 1.8%. In addition, a drainage test of the drain material was performed, and it was confirmed that drainage to the catchment basin was good one year later, and the ground surface was well drained along with watering (see Table 1). Therefore, it was found that the obtained drain material had excellent pressure resistance and drainage performance.

Comparative Example 1 The same conjugate fiber as in Example 1 was made into a web having a basis weight of 45 g / m ² , and the web was heated with a through-air heater set at 143 ° C., and the diameter was 76 m on a conveyor belt.
m was wound around an iron core to form a filtration layer, which was used as a drain material. At this time, 0.12 MPa (1.2 kgf / c
An iron core was supported by a support at a pressure of m ² ), and a filtration layer was formed while applying linear pressure to the web by the load of the core and the wound web. The drain material was wound up to a specified size, and after cooling the drain material, the core was taken out, and both ends were cut off to obtain a drain material. This drain material had an outer diameter of 114 mm, a wall thickness of 19 mm, a weight of 3855 g / (2 m), and an overall porosity of 63.0%. In addition, 16624 N / m (1662 kgf / m)
Pressure strength. When the particle size distribution of the drain material in the thickness direction was measured, it was found that the drain material had only a layer having a porosity gradient as shown in FIG. 3A. In addition, drainage test of the drainage material confirmed that drainage to the catchment basin was good for half a year, and the ground surface was well drained along with water sprinkling. The amount of drainage decreased, and puddles became visible on the ground surface (drainage worsened). One more
After the lapse of year, the amount of drainage to the catchment basin was visually reduced to about half compared with the drain material of Example 1, and the drainage of the ground was also inferior (see Table 1). Thus, this drain material was excellent in pressure resistance performance, but had a short filtration life and was not suitable for long-term use.

Comparative Example 2 A test sample was prepared in which a polyester nonwoven fabric having a basis weight of 200 g / m ² and a thickness of 2 mm was double wound around a cylindrical resin molded product (having a net-shaped opening). This specimen is
Outer diameter 80mm, inner diameter 74mm, porosity 98.5%
It is. Also, this test piece was 900 N / m (90 kg
f / m). Using the test specimen, when the particle size distribution measurement in the thickness direction of the test specimen was performed, since there was little room for penetration in the thickness direction, earth and sand were deposited on the surface of the nonwoven fabric, and the measurement could not be performed. Was. In addition, when a drainage test was performed, the amount of drainage into the catchment basin decreased in about two months, and puddles began to be seen on the ground surface (drainage deteriorated). After one year, there was almost no drainage to the catchment basin, and puddles due to sprinkling became widespread on the ground surface (see Table 1). Therefore, this test specimen had low pressure resistance performance, an extremely short filtration life, and was unsuitable as a drain material.

[0041]

[Table 1]

[0042]

The drain material of the present invention has a porosity in the thickness direction between the first filtration layer and the third filtration layer having a porosity gradient in which the porosity continuously decreases in the thickness direction. Since the second filtration layer with a constant value is sandwiched and laminated so that the porosity gradient is continuous, it is better to collect and discharge excess water in the ground compared to conventional drain materials. In addition, the drain material is unlikely to be clogged because the drain material is not finely packed due to sudden intrusion of soil particles and surplus water into the drain material, and since the drain material has a long filtration life, it can be used for a long time. it can. Furthermore, the drain material of the present invention has a high pressure resistance and a good water permeability even under a high compression load because the web made of the heat-adhesive conjugate fiber is heat-sealed to form a filtration layer. Have. Further, the drain material of the present invention is a drain material having excellent rigidity and durability. In particular, when the heat-adhesive conjugate fiber is a combination of polyolefins, it is excellent in workability because it is lightweight. Therefore, drainage can be improved by installing the drain material of the present invention in the soil of a ground or a stadium, and by installing it in sloped soil, the soil is stabilized and the risk of collapse is improved. Can be lowered. Moreover, by constructing in the fields, not only can the drainage be good, but also the water retention can be enhanced. Furthermore, by constructing it on road facilities or railway facilities, it is possible to reduce the risk of mud sprays and the like. Further, by constructing a stratum containing a large amount of methane gas or the like, degassing is also possible. In addition, by driving the drain material of the present invention into the vicinity of the root of a tree, the exchange of oxygen and carbon dioxide in the soil can be smoothly performed, and the growth can be activated. The drain material of the present invention is:
For example, it can be used in combination with many materials, such as fabrics, films, metal nets, construction materials, civil engineering materials, agricultural materials, and the like.
It is a drain material that can be used as agricultural material and also as building material.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a particle size distribution measuring device.

FIG. 2 is a schematic diagram showing the relationship between the depth in the thickness direction of the drain material and the particle size distribution.

FIG. 3 is a schematic diagram showing a relationship between a depth in a thickness direction of a first filtration layer or a third filtration layer and a particle size distribution.

[Explanation of symbols]

A: Particle size distribution measuring device B: Drain material sample C: Joint D: PVC pipe E: Earth and sand F: Water supply hose G: Film blockage H: Equipment container (width × depth × height = 400 × 550 × 32)
X: Depth in the thickness direction (mm) Y: Average trapping particle size (μm) a: Maximum head height (100 mm) b: Minimum head height (80 mm) c: Head height d: Flow direction e: First filtration Curve portion indicating the trapped particle size of the layer f: Curve portion indicating the trapped particle size of the second filtration layer g: Curve portion indicating the trapped particle size of the third filtration layer h: of the filtration layer having a porosity gradient Curve portion indicating trapped particle size 2A: Curve portion indicating trapped particle size of second filtration layer (graph in which trapped particle size is almost constant) 2B: Curve portion indicating trapped particle size of second filtration layer (Graph in which trapped particle size rises) 2C: Curve indicating trapped particle size of second filter layer (graph in which trapped particle size falls) 3A: Collected particle in first filter layer or third filter layer Curve portion indicating diameter (graph in which trapped particle diameter changes linearly) 3B: Indicates trapped particle diameter of first filtration layer or third filtration layer Line portions (graphs collecting particle size varies 擬直 Ray)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D043 DA09 4D019 AA03 BA13 BB02 BB10 CA03 DA03 4F100 AK05 AK07 AR00A AR00B AR00C BA03 BA07 BA10A BA10C BA43A BA43C DA11 DG01A DG01B DG01C DG06A03 GB03 EC03 EC04 GB03 ECG JL13C YY00A YY00B YY00C

Claims (4)

[Claims] 1. A drain material having a filtration layer to which a web of heat-adhesive conjugate fibers is heat-sealed, wherein the filtration layer comprises three layers having a continuous porosity gradient, and a first layer corresponding to an outer layer. The third filtration layer corresponding to the filtration layer and the inner layer is a layer having a porosity gradient in which the porosity continuously decreases in the thickness direction, and the second filtration layer corresponding to the intermediate layer has a void in the thickness direction. A drain material which is a layer having a constant rate and has a filtration layer laminated in the order of a first filtration layer / a second filtration layer / a third filtration layer. 2. A cylinder formed by winding a web made of a heat-adhesive conjugate fiber.
The drain material as described. 3. The fineness of the heat-adhesive conjugate fiber is from 10 to 10.
The drain material according to claim 1, wherein the drain material is 0 dtex. 4. The heat-adhesive conjugate fiber according to claim 1, wherein the heat-adhesive conjugate fiber comprises a low-melting resin having a melting point difference of 10 ° C. or more and a high-melting resin. The drain material according to claim 1.