JP3674985B2 - Drainage material for soil water - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a drainage material for soil water used for drainage on embankments, soft ground, and the like.
[0002]
[Prior art]
Conventionally, what consists of various nonwoven fabrics is used as a drainage material for soil water. For example, a strip or sheet drainage material for soil water is laid horizontally in the embankment, its end is exposed on the slope of the embankment, and the soil water in the embankment is drained from that end. It has been broken. In addition, a strip-shaped or sheet-shaped drainage material for soil water is inserted vertically into the soft ground, its end is exposed on the soft ground, and the soil water in the soft ground is drained from that end. Has been done. The non-woven fabric is formed by collecting short fibers or long fibers as constituent fibers, and has a large number of voids between the constituent fibers. If such a non-woven fabric is embedded in embankment or soft ground and one end of the non-woven fabric is exposed to the atmosphere, soil water is drained to the outside through the constituent fiber gaps in the non-woven fabric. It is. However, in the case of this nonwoven fabric, when the pressure in the soil (earth pressure) is increased, the gap between the constituent fibers is crushed, so that the soil water does not flow and good drainage cannot be performed.
[0003]
For this reason, by inserting a small-diameter pipe or the like into the nonwoven fabric, even if the constituent fiber gap of the nonwoven fabric is crushed, it is possible to secure a water passage by the pipe or the like. However, such a water channel is not drained by capillarity such as gaps between the constituent fibers of the nonwoven fabric, so when there is a large amount of water in the soil, it is drained from the water channel, but the amount of water in the soil is When the amount was small, good drainage could not be expected.
[0004]
[Problems to be solved by the invention]
Therefore, the present inventors have examined how to prevent the constituent fiber gaps in the nonwoven fabric from being crushed even when a high earth pressure is applied to the nonwoven fabric. First, the present inventors considered why the constituent fiber gaps were crushed by a high earth pressure in a conventionally used nonwoven fabric. As a result, it was considered that the constituent fibers used in the conventional nonwoven fabric are close-packed by high earth pressure because the cross-section is almost circular.
[0005]
Therefore, it was considered that if the cross-section of the constituent fiber is irregular (star shape, triangle, etc.), the close-packing is difficult and the constituent fiber gap is not crushed even by high earth pressure. However, this attempt did not give satisfactory results. The reason is considered as follows. In other words, even if the cross section is irregular, when a high earth pressure is applied, the constituent fibers that are in contact with each other slip and tend to gradually close-pack.
[0006]
  The present inventors further examined why the constituent fibers slip even though the cross section of the constituent fibers is irregular. As a result, the fiber having an irregular cross-section is obtained by making the shape of the spinning hole into a star shape or a triangular shape at the time of melt spinning, but it is a very short time such as before being pulled after spinning the fiber. The thermoplastic polymer constituting the fiber has fluidity during that time, and the fiber surface is rounded by this fluidity and surface tension. In other words, even if the cross-section of the fiber is irregular,(Kado. Hereinafter, the term “corner” in this specification is used to mean “Kado”.)There is no slippery, rounded state. Accordingly, when a high earth pressure is applied to the nonwoven fabric in which such constituent fibers are accumulated, the constituent fibers slip.
[0007]
Accordingly, the present inventors have made various studies to obtain fibers having substantial corners on the surface in order to make the constituent fibers difficult to slip, and as a result, instead of directly melt spinning the cornered fibers, It was thought that a fiber having an angle on the surface can be easily obtained by dividing and splitting the composite-type split fiber after melt-spun composite-type split fiber. The present invention has been made based on such a technical idea.
[0008]
[Means for Solving the Problems]
  That is, the present invention provides the weight produced by split splitting of a composite split fiber in which a thermoplastic polymer A and a thermoplastic polymer B that is incompatible with the polymer A are combined. Nonwoven fabric comprising thermoplastic fiber A made of coalescence A and thermoplastic fiber B made of polymer B as constituent fibersOnly drainage materialThe thermoplastic fiber A and / or the thermoplastic fiber B relates to a soil water drainage material characterized in that the surface thereof has a continuous corner in the longitudinal direction.
[0009]
First, the composite split fiber used in the present invention will be described. The composite-type split fiber is a composite of a thermoplastic polymer A and a thermoplastic polymer B that is incompatible with the polymer A. The form of the composite is arbitrary, but at least one of the fiber A formed of the thermoplastic polymer A and the fiber B formed of the thermoplastic polymer B is an angle where the surface is continuous in the longitudinal direction. It must be in a form that has 1 to 4 are cross-sectional views of composite-type split fibers used in the present invention. The scattered dot portion indicates that it is the thermoplastic polymer B, and the shaded portion indicates that it is the thermoplastic polymer A.
[0010]
In the case of a composite split fiber having a cross section as shown in FIG. 1, the fiber B produced by split splitting has a corner 1 that is continuous in the longitudinal direction on the surface thereof. Sixteen corners 1 are formed in the fiber B. On the other hand, the fiber A formed of the thermoplastic polymer A is a fiber having a circular cross section and no corners. In the case of a composite-type splitting fiber having a cross section as shown in FIG. 2 (a hollow composite-type splitting fiber, the white portion in FIG. 2 indicates that it is hollow), both fiber A and fiber B , A fiber having a continuous corner 1 in the longitudinal direction on its surface. Both fiber A and fiber B have four corners 1 per fiber. Also in the case of a composite-type split fiber having a cross section as shown in FIG. 3, both the fiber A and the fiber B are fibers having corners 1 continuous in the longitudinal direction on the surface thereof. Both fiber A and fiber B have three corners 1 per fiber. Also in the case of a composite-type split fiber having a cross section as shown in FIG. 4, both the fiber A and the fiber B are fibers having corners 1 continuous in the longitudinal direction on the surface thereof. One fiber A has two corners 1, and one fiber B has 12 corners 1.
[0011]
As is clear from the above description, the composite split fiber used in the present invention is a composite boundary portion of the thermoplastic polymer A and the thermoplastic polymer B (joint portion between the polymer A and the polymer B). Thus, the corner 1 is obtained on the outer peripheral surface of the composite split fiber. In the case of the cross section as shown in FIG. 2, the angle 1 is obtained even on the inner peripheral surface of the composite-type split fiber, and in the case of the cross-section as shown in FIG. It is done. Therefore, the thermoplastic polymer A and the thermoplastic polymer B are incompatible with each other because the affinity between the two is lowered and the two are easily separated, so that the polymer A and the polymer B are joined. This is because it is easy to obtain the corner 1 that is continuous in the longitudinal direction at the portion. When the polymer A and the polymer B are compatible with each other, the bonding strength between the two is high and it is difficult to peel off, and there is a possibility that a continuous corner 1 may be taken off in peeling.
[0012]
Specific combinations of the polymer A and the polymer B (polymer A / polymer B) include polyamide polymer / polyester polymer, polyolefin polymer / polyester polymer, polyolefin polymer / polyamide. A polymer or the like can be used. And as a polyester-type polymer, polyethylene terephthalate, polybutylene terephthalate, or copolyester which has these as a main component can be used. As the polyamide-based polymer, nylon 6, nylon 46, nylon 66, nylon 610, copolymerized nylon mainly containing these, or the like can be used. As the polyolefin polymer, polypropylene, high-density polyethylene, linear low-density polyethylene, ethylene-propylene copolymer, or the like can be used. In addition, a lubricant, a pigment, a matting agent, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a conductive agent, a heat storage agent, and the like are added to the polymer A or the polymer B as desired. It may be.
[0013]
It is preferable that the polymer A and the polymer B have a predetermined melting point difference. For example, the polymer B preferably has a melting point 30 to 180 ° C. higher than the melting point of the polymer A, more preferably 40 to 160 ° C., and most preferably 50 to 140 ° C. The reason for providing such a difference in melting point is that there are cases where dotted fusion zones are provided in the nonwoven fabric in which the thermoplastic fibers A formed of the polymer A and the thermoplastic fibers B formed of the polymer B are accumulated. Because there is. The fusion zone is present in the non-fusion zone by fusing the thermoplastic fiber A and the thermoplastic fiber B or the composite type split fiber by softening or melting the thermoplastic fiber A or the polymer A having a low melting point. The thermoplastic fibers A and B are fixed. Therefore, if the difference in melting point is less than 30 ° C., if the thermoplastic fiber A or the polymer A is softened or melted, the thermoplastic fiber B or the polymer B may also be softened or melted, and the fiber form disappears in both cases. As a result, a hole is opened in the fusion zone, and the strength of the drainage material for soil water obtained may be reduced. In addition, it is difficult to perform composite melt spinning of the polymer A and the polymer B having a melting point difference of 180 ° C. or more, which makes it difficult to produce the composite split fiber used in the present invention. The melting points of the polymers A and B are temperatures that give extreme values of a melting absorption curve obtained by heating from room temperature at a heating rate of 20 ° C./min using a DSC-2C type manufactured by PerkinElmer. .
[0014]
The quantitative ratio of the polymer A and the polymer B in the composite split fiber is an item that can be arbitrarily determined. In the case where the fusion zone is provided by providing a difference in melting point between the polymer A and the polymer B. The polymer A / polymer B is preferably 20 to 80/80 to 20 (parts by weight). For example, when the amount of the polymer A having a low melting point is less than 20 parts by weight, the degree of fusion in the fusion zone becomes low, and the strength of the obtained groundwater drainage material may be reduced. Further, when the amount of the polymer B having a high melting point is less than 20 parts by weight, the amount of the polymer B or the thermoplastic fiber B that maintains the fiber form in the fusion zone is decreased, and there is a possibility that holes are formed in the fusion zone. is there. If a hole is opened in the fusion zone, the strength of the drainage material for soil water obtained may decrease.
[0015]
The fineness of the composite split fiber used in the present invention is also a matter that can be arbitrarily determined, but generally it is preferably 2 to 12 denier. It is difficult to produce a composite split fiber having a fineness of less than 2 denier. Further, when the fineness of the composite split fiber exceeds 12 denier, the fineness of the thermoplastic fiber A and the thermoplastic fiber B generated by split splitting is increased, the gap between constituent fibers is increased, and capillary action is caused. There is a tendency for the passage of soil water to decrease. That is, the fineness of the thermoplastic fiber A and the thermoplastic fiber B is preferably such that the capillary phenomenon in the gaps between the constituent fibers is satisfactorily exhibited, and is preferably about 0.02 to 2 denier.
[0016]
The fiber length of the composite split fiber is arbitrary, and may be a short fiber having a short fiber length or a long fiber having a long fiber length. In particular, in the present invention, it is preferable to use substantially endless long fibers. Substantially endless long fibers can be accumulated as they are without performing the melt melt spinning and cutting the resulting fibers. Have. If the composite split fiber is a substantially endless long fiber, the thermoplastic fiber A and the thermoplastic fiber B obtained by splitting the split fiber are also substantially endless long fibers. Accordingly, the angles formed on the surface of the thermoplastic fiber A and / or the thermoplastic fiber B are infinitely continuous. Then, the gap maintained between the constituent fibers is easily continued due to the presence of the corners, and the soil water easily passes through the gap.
[0017]
In order to split the composite-type split fibers, first, a fiber web in which the composite-type split fibers are integrated is obtained. When the composite-type split fibers are short fibers, a fiber web may be obtained by a conventionally known card method or the like. In the case where the composite-type split fibers are substantially endless long fibers, a fiber web may be obtained by a conventionally known spunbond method or the like. In the present invention, it is preferable to employ a spunbond method, which is a method as described below. That is, the thermoplastic polymers A and B are introduced into a spinneret having a large number of complex spinning holes, and a large number of complex type split fibers are obtained by a conventionally known complex melt spinning method. A large number of melt-spun composite split fibers are then cooled and introduced into an air soccer. The air soccer is usually called an air jet, and causes the fiber to be conveyed and the fiber to be stretched by sucking and feeding air. The composite split fiber introduced into the air soccer is conveyed to the outlet of the air soccer while being drawn. Then, a large number of composite-type split fibers are opened by the opening device provided at the outlet of the air soccer. As the opening method, a conventionally known method is employed, and for example, a corona discharge method, a friction charging method, or the like is employed. Then, the opened composite split fibers are collected on a moving conveyor such as a wire mesh to form a fiber web.
[0018]
A physical impact is given to the fiber web obtained as described above by needling or water needling. Needling is a method of passing a needle with a needle many times in the thickness direction of the fiber web. Water needling is a method of penetrating a high-pressure columnar flow in the thickness direction of the fiber web. When such a method is applied to the fiber web, an impact is given to the composite split fiber, and the composite split fiber is split and split by this impact, and the fiber A and the thermoplastic polymer B made of the thermoplastic polymer A. The fiber B which consists of this produces | generates, and the nonwoven fabric used by this invention is obtained. Further, simultaneously by this method, the split fibers A and B are entangled three-dimensionally with each other. Therefore, since the constituent fibers in the nonwoven fabric are entangled three-dimensionally with each other, the form is stable and the strength becomes high, and it can be used as it is as a drainage material for soil water.
[0019]
Further, the fiber web may be subjected to stagnation processing to divide and split the composite split fiber. In the stagnation process, when a bending force is applied to the composite split fiber, split split is generated by this force, and the thermoplastic fibers A and B are generated. Examples of the squeezing method include a buckling compression method in which a fiber web is bent at a higher introduction speed than a derivation speed when the fiber web is introduced into a roll, and a high-pressure liquid flow that applies a high-pressure liquid flow to the fiber web A method of applying a processing method can be adopted. In addition to this method, any method can be adopted as long as the stagnation action that splits and splits the composite split fiber is applied to the fiber web. When the buckling compression method is adopted, it is preferable to use a microcreper machine manufactured by Mike Rex or a cam fit machine manufactured by Uenoyama Kiko. Moreover, when employ | adopting a high pressure liquid flow processing method, it is preferable to use the high pressure liquid flow dyeing machine generally used. In the case of the high-pressure liquid flow treatment method, since the fiber web absorbs water, it is necessary to dry after the treatment. However, in the case of the buckling compression method, since this is not the case, the drying step is unnecessary, and economically. It is advantageous.
[0020]
By the kneading process, thermoplastic fibers A and B are produced, and a nonwoven fabric is obtained. In this case, unlike the case of needling or the like, the thermoplastic fibers A and B are not substantially entangled three-dimensionally, the form of the nonwoven fabric is not stable, and the tensile strength is sufficient. It does not have high strength. Therefore, it is preferable to interspers the fusion zone by the softening or melting of the thermoplastic fiber A or the thermoplastic fiber B. Preferably, the fused areas are interspersed so that there are continuous non-fused areas. This is because the soil water passes through the gaps between the constituent fibers in the non-fused area. That is, in the case where the fused area is a continuous line, the non-fused area is cut off by the fused area, and there is a risk that the passage of soil water may be blocked by the fused area. . As a preferable means for providing the fusion zone, a thermoplastic polymer A having a melting point lower than that of the thermoplastic polymer B is adopted, and the thermoplastic fiber A is a constituent fiber by softening or melting. The plastic fibers A and B may be fused to fix the thermoplastic fibers A and B in the fused area. Even when the constituent fibers are entangled three-dimensionally with each other by needling or water needling, the above-described fusion zone may be provided in order to give high strength to the nonwoven fabric.
[0021]
In the above example, when the fusion zone is provided, the composite segmented fiber is split or split and then the thermoplastic polymer A is softened or melted. It may be provided. That is, the fiber web in which the composite-type split fibers are accumulated may be provided with interspersed fusion areas. The composite split fiber before split splitting is in a state where the thermoplastic polymers A and B are not separated, but the low melting thermoplastic polymer A is exposed on the surface of the composite split fiber For example, the polymer A can be softened or melted to fuse the composite-type split fibers to provide a fusion zone. Then, after that, the composite-type split fiber in the non-fused area may be split and split. As the split splitting method at this time, the above-described needling, water needling or squeezing can be employed. When the difference in melting point between the thermoplastic polymers A and B is small (for example, when the difference between the melting points is less than 30 ° C.), both the polymers A and B are softened or melted in the fusion zone, and composite split fibers May be fused. Moreover, also when providing a fusion | melting area after split splitting, both the thermoplastic fibers A and B may be softened or melted, and the thermoplastic fibers A and B may be fused.
[0022]
  In order to improve the shape stability of the nonwoven fabric and achieve high strength in the nonwoven fabric, there is a method of laminating a reinforcing material on one or both sides of the nonwoven fabric in addition to the method of providing a fusion zone. As the reinforcing material, a high-strength woven fabric, knitted fabric, net, other non-woven fabric, or the like can be used. As the reinforcing material, it is preferable that water in the soil can be satisfactorily passed in the thickness direction. This is because soil water does not flow into the non-woven fabric if a reinforcing material such as a metal plate that cannot pass water in the thickness direction is employed. However, even if it is a material that cannot pass water in the thickness direction, such as a metal plate, if it is laminated only on one side without being laminated on both sides of the nonwoven fabric, soil water will flow into the nonwoven fabric from the other side. Can be used. When reinforcing materials are laminated, the need to provide a fusion zone for improving the shape stability of the nonwoven fabric is reduced, but a fusion zone is provided in the nonwoven fabric for the purpose of suppressing fuzz on the nonwoven fabric surface. Needless to say, there is no problem.Needless to say, this reinforcing material is used for improving the shape stability of the nonwoven fabric, which is a drainage material, and does not have a function as a drainage material.
[0023]
It is preferable to apply a surfactant to the surface of the constituent fibers of the nonwoven fabric constituting the drainage material for soil water. As the surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant and the like can be generally used. Of these, nonionic surfactants are preferable, and monoesters of lauric acid, stearic acid, and oleic acid, and polyoxyethylene adducts of lauryl alcohol, stearyl alcohol, and oleyl alcohol are more preferable. When such a surfactant is applied to the surface of the constituent fiber, the surface of the constituent fiber is easily wetted by the soil water, the capillary phenomenon is likely to work, and the drainage efficiency of the soil water is improved. As a method for imparting a surfactant to the thermoplastic fibers A and B, a surfactant solution may be attached to a nonwoven fabric in which the thermoplastic fibers A and B are accumulated by a spray method, a dipping method, or the like. In addition, a surfactant solution may be attached to the fiber web formed by collecting the composite split fibers before split splitting or the composite split fibers by spraying, dipping, or the like.
[0024]
The drainage material for soil water according to the present invention is made of a nonwoven fabric as described above. Then, this non-woven fabric is cut into a predetermined length of strip or sheet to form a predetermined shape, laminated with a reinforcing material as necessary, and laid horizontally in the embankment or vertically in the soft ground By inserting it and exposing its end to the atmosphere, it becomes a drainage material for soil water. In addition, the fabric weight of the nonwoven fabric to be used is generally 10 to 250 g / m.²The degree is preferred.
[0025]
【Example】
Example 1
As the thermoplastic polymer A, a high-density polyethylene having a melting point of 130 ° C. and a melt index value (measured according to the method described in ASTM D1238 (E)) of 20 g / 10 minutes was prepared. On the other hand, as the thermoplastic polymer B, a polyethylene terephthalate having a melting point of 258 ° C. and a relative viscosity of 1.38 at 20 ° C. when dissolved in an equal mixed solvent of tetrachloroethane and phenol was prepared. Then, composite melt spinning was performed using the polymer A and the polymer B. At this time, a composite spinning machine base having a spinneret with 162 composite spinning holes and 4 spindles was used. The composite melt spinning is performed so that the single-hole discharge rate is 1.20 g / min, the discharge rate of the polymer A is 0.60 g / min, and the discharge rate of the polymer B is 0.60 g / min. did. The spinning temperature was 230 ° C. for polymer A and 285 ° C. for polymer B.
[0026]
After the composite melt spinning, the composite split fiber was pulled through 6 air soccer balls per spindle arranged at a position 120 cm below the spinneret, and taken up at a speed of 4000 m / min. The composite segmented fiber thus obtained had a cross section as shown in FIG. 1 and a fineness of 2.70 denier. Subsequently, the pulled composite type split fiber group was opened by corona discharge and deposited on a moving conveyor net to form a fiber web. This fiber web was introduced between an uneven roll heated to 120 ° C. and a smooth roll heated to 120 ° C. As a result, the area of the fiber web in contact with the convex part of the uneven roll was heated in the thickness direction, the polyethylene of the composite-type split fibers softened, and the composite-type split fibers were fused together. The fused area corresponding to the convex part of the concave-convex roll was arranged in the form of dots, and the total area was 14% with respect to the nonwoven fabric surface area.
[0027]
As described above, a fiber web was obtained in which the composite split fibers were bonded to each other in the fusion zone, and the composite split fibers were simply accumulated in the non-fusion zone. The fiber web was subjected to a squeezing process using a Microcreper II manufactured by Mike Rex. The processing conditions at this time were a processing speed of 10 m / min and a nip pressure between a pair of supply rolls of 6 kg / cm.², Upper retarder pressure 3kg / cm², Supply roll temperature 50 ° C, Lower retarder pressure 5kg / cm²The distance between the contact pressure center point between the supply rolls and the upper retarder was 5 mm, and the distance between the contact pressure center point between the supply rolls and the lower retarder was 10 mm.
[0028]
The non-woven fabric obtained as described above has a 0.19 denier polyethylene terephthalate long fiber and a 1.5 denier polyethylene long fiber produced by split splitting of a composite split fiber by squeezing in a non-fusion region. In the fusion zone, the composite-type split fibers were bonded together by the fusion of polyethylene in the composite-type split fibers. And the basis weight of this nonwoven fabric is 50 g / m²The tensile strength was 23.1 kg / 5 cm. If this nonwoven fabric was cut into long strips, it could be used as it is as a drainage material for soil water.
[0029]
Example 2
As thermoplastic polymer A, nylon 6 having a melting point of 225 ° C. and a relative viscosity of 2.57 measured at 25 ° C. with 96% concentrated sulfuric acid was prepared. On the other hand, the same polyethylene terephthalate as used in Example 1 was prepared as the thermoplastic polymer B. Then, composite melt spinning was performed using the polymer A and the polymer B. At this time, except for using a 16-divided hollow radial composite spinning hole that gives a composite-type splitting fiber having a cross section as shown in FIG. 2 as the spinning hole, and the spinning temperature of the polymer A is set to 270 ° C. In the same manner as in Example 1, composite melt spinning was performed.
[0030]
And it pulled with the air soccer like Example 1, and the cross section was a form as shown in FIG. 2, and obtained the composite type | mold split fiber whose fineness is 2.7 denier. Subsequently, a fiber web is formed in the same manner as in Example 1, and a fiber web having interspersed fusion zones is obtained in the same manner as in Example 1 except that the temperature of the uneven roll and the smooth roll is 220 ° C. It was.
[0031]
The obtained fiber web was subjected to scumming using a loco-type liquid flow dyeing machine (made by Hokuriku Processing Machine). The conditions for applying the liquid flow are as follows: liquid temperature 100 ° C., fiber web speed 100 m / min, nozzle pressure 3 kg / cm.²The time was 1 hour. After squeezing with a loco-type liquid dyeing machine, it was dehydrated and dried to obtain a nonwoven fabric.
[0032]
The obtained non-woven fabric is a mixture of 0.17 denier nylon 6 long fibers and polyethylene terephthalate long fibers produced by split splitting of the composite split fibers by kneading in the non-fusion zone, In the fusion zone, the composite-type split fibers were bonded to each other by the fusion of nylon 6 in the composite-type split fibers. The basis weight of this nonwoven fabric is 50 g / m²Met. If this nonwoven fabric was cut into long strips, it could be used as it is as a drainage material for soil water.
[0033]
Comparative Example 1
Using a polyester short fiber with a fineness of 1 denier and a fiber length of 51 mm and a circular cross section, the parallel card is approximately 50 g / m.²After the web was prepared, it was introduced into the same uneven roll and smooth roll as in Example 1. The basis weight is 50 g / m under the same conditions as in Example 1 except that the temperature of each roll is 240 ° C.²A non-woven fabric was prepared. This nonwoven fabric is provided with the same fusion zone as in Example 1, and this fusion zone is due to softening or melting of the polyester staple fibers.
[0034]
Comparative Example 2
Polypropylene having a melting point of 160 ° C. and MFR of 120 g / 10 min was spun at a spinning temperature of 340 ° C. with a single-hole discharge rate of 0.2 g / min, and the spun polymer stream was subjected to a high-pressure high-temperature air stream (temperature: 370 ° C., pressure: 1. 2kg / cm²), Cooled and formed into fibers, and then collected on a wire mesh belt disposed at a position 20 cm away from the die equipped with spinning holes and moving at a speed of 6.7 m / min. , Deposited weight 50g / m²Created a non-woven web. Since the fibers in the nonwoven web are formed by being discharged in a melted state, the cross section is often circular, and even if it is not circular, it does not substantially have corners. . Further, at this time, the fineness of the fibers was 0.1 denier, which substantially occupied the nonwoven web. Using this nonwoven web, it was introduced into the same uneven roll and smooth roll as in Example 1. The basis weight is 50 g / m under the same conditions as in Example 1 except that the temperature of each roll is 140 ° C.²A non-woven fabric was prepared. This non-woven fabric is provided with the same fusion zone as in Example 1, and this fusion zone is due to the softening or melting of the polyolefin fibers.
[0035]
After compressing the nonwoven fabric according to Example 1, the nonwoven fabric according to Comparative Example 1, and the nonwoven fabric according to Comparative Example 2 in the thickness direction, the water absorption height is measured by the following method based on the Bayrec method described in JIS L-1096. Was measured. That is, the longitudinal length of the nonwoven fabric is 20 cm, the lateral length is 2.5 cm, 10 strips are cut from the nonwoven fabric, the lateral length of the nonwoven fabric is 20 cm, and the longitudinal length is 5 strips were cut from a non-woven fabric. These strips are suspended with a pin on a horizontal bar supported at a certain height on a water tank containing 20 ± 2 ° C. distilled water. Align the bottom of the strips in a line and lower the horizontal bar so that 1 cm at the bottom of the strips is immersed in water. Next, the height (mm) of the water after standing for 10 minutes is measured. In addition, the elevated height of water after 20 and 30 minutes was also measured. In the measurement, 0.2% by weight of a cationic surfactant was applied to the strip. This result is as shown in FIG. 5. When the nonwoven fabric according to Example 1 was used, the water absorption height was higher than that of the nonwoven fabrics according to Comparative Examples 1 and 2. Therefore, it can be seen that the nonwoven fabric according to Example 1 exhibits a better capillary phenomenon than the nonwoven fabrics according to Comparative Examples 1 and 2. As is clear from this, the nonwoven fabric according to Example 1 can be suitably used as it is as a drainage material for soil water.
[0036]
[Action]
The drainage material for soil water according to the present invention is made of a nonwoven fabric. And as the constituent fibers in this nonwoven fabric, thermoplastic fibers A and B produced by split splitting of composite split fibers are employed. At least one of the fibers A and B has a continuous corner in the longitudinal direction on the surface thereof. Therefore, even if a high earth pressure is applied to the nonwoven fabric due to the presence of the continuous corners in the longitudinal direction, it is difficult to slip between the constituent fibers that are in contact with each other, and the closest packing is prevented. A gap in which capillary action is exerted is maintained between them.
[0037]
【The invention's effect】
Therefore, when the soil water drainage material according to the present invention is laid horizontally in the embankment or inserted vertically into the soft ground, a high earth pressure is applied to the soil water drainage material. In addition, the capillary phenomenon is satisfactorily exerted, and there is an effect that the soil water can be quickly drained out of the embankment and out of the soft ground.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a cross section of a composite split fiber used in the present invention.
FIG. 2 is a view showing an example of a cross section of a composite-type split fiber used in the present invention.
FIG. 3 is a view showing an example of a cross section of a composite-type split fiber used in the present invention.
FIG. 4 is a view showing an example of a cross section of a composite split long fiber used in the present invention.
5 is a graph showing measurement results of water absorption heights of nonwoven fabrics according to Example 1, Comparative Example 1, and Comparative Example 2. FIG.
[Explanation of symbols]
A Thermoplastic polymer A
B Thermoplastic polymer B
1 Contiguous corners in the longitudinal direction

Claims (6)

Thermoplastic composed of the polymer A produced by split splitting of a composite split fiber in which a thermoplastic polymer A and a thermoplastic polymer B incompatible with the polymer A are combined. Only the nonwoven fabric comprising the fiber A and the thermoplastic fiber B made of the polymer B as a constituent fiber is used as a drainage material. Drainage material for soil water, characterized by having (corner) .   The drainage material for soil water according to claim 1, wherein the constituent fibers are entangled three-dimensionally with each other.   3. The soil according to claim 1, wherein fusion zones scattered in the nonwoven fabric are provided, and the fusion fibers are fused with the constituent fibers by softening or melting of the thermoplastic polymer A or the thermoplastic polymer B. 4. Waste water for middle water.   The drainage material for soil water according to any one of claims 1 to 3, wherein the constituent fibers are substantially endless long fibers.   The drainage material for soil water according to any one of claims 1 to 4, wherein a surfactant is applied to the constituent fibers. The drainage material for soil water according to any one of claims 1 to 5, wherein a reinforcing material is laminated on one side or both sides of the nonwoven fabric.

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