JP4717673B2 - Water absorption / water retention sheet - Google Patents

Description

  The present invention relates to a water absorption / water retention sheet. More specifically, the present invention relates to a water-absorbing / water-retaining sheet that is excellent in water permeability and water absorption and that can moderately suppress moisture divergence. The water-absorbing / water-retaining sheet of the present invention is particularly useful as a herbicidal sheet that prevents weed germination and promotes the growth of fruit trees and trees.

  In fields such as agricultural sheets, civil engineering sheets, sanitary materials, and the like, sheets having excellent water absorption and water retention are required and various proposals have been made (see Patent Documents 1 and 2). However, it has been pointed out that these water-absorbing / water-retaining sheets have insufficient water absorption performance and are inferior in strength.

  On the other hand, water supply, fertilizer addition, and weeding work are carried out for the growth of vegetables, fruit trees, trees grown in farmland, gardens, green belts, etc., but weeds grow fast and must be frequently weeded. It must be labor intensive and time consuming. As the herbicidal work, there is a method of spraying herbicides, etc., but the effect of the herbicides is temporary and there is a tendency to refrain from using herbicides due to the recent increase in environmental awareness. Therefore, various types of herbicidal sheets that are laid on the cultivation ground to prevent weed germination have been proposed (see, for example, Patent Documents 3 to 6).

However, these herbicidal sheets do not have sufficient water absorption and are inferior in water retention, so it is necessary to spray water frequently especially in midsummer. Moreover, since there is no water absorption by rain water in a cultivation house, regular watering work is needed. On the other hand, in recent years, farmers are required to reduce their labor force with the aging of farmers.
Under the background as described above, there is a need for a herbicidal sheet that lowers the frequency of water spraying and keeps the water retention of the ground moderately, and further prevents weeds from germinating.

JP 2002-347153 A Japanese Patent Laying-Open No. 2005-082904 JP-A-8-103177 Japanese Patent Laid-Open No. 10-262472 Japanese Patent Laid-Open No. 9-099980 Japanese Patent Laying-Open No. 2005-034013

  The present invention has been made in view of the current situation, and an object of the present invention is to provide a water-absorbing / water-retaining sheet having excellent water absorption and appropriate water retention and excellent in herbicidal properties. .

  That is, the present invention is a water-absorbing / water-retaining sheet in which a dry nonwoven fabric containing polyvinyl alcohol fibers, hydrophobic fibers, and heat-fusible fibers is laminated on at least one surface of a meltblown nonwoven fabric.

  According to the present invention, it is possible to obtain a water-absorbing / water-holding sheet having excellent water absorption, water permeability and appropriate water retention. Moreover, by using the water-absorbing / water-retaining sheet of the present invention as a herbicidal sheet, weeds can be prevented from germinating, and the growth of vegetables, fruit trees and trees is promoted.

  As described above, the water-absorbing / water-holding sheet of the present invention is formed by laminating a dry nonwoven fabric containing polyvinyl alcohol fibers, hydrophobic fibers, and heat-fusible fibers on one or both sides of a meltblown nonwoven fabric. The melt blown nonwoven fabric and the dry nonwoven fabric are bonded by interfiber fusion.

The melt-blown nonwoven fabric constituting the water-absorbing / water-holding sheet of the present invention is preferably a melt-blown nonwoven fabric made of ultrafine fibers having an average fiber diameter of 15 μm or less and having a basis weight of 15 to 100 g / m ² . If the average fiber diameter of the fibers constituting the melt blown nonwoven fabric exceeds 15 μm, the diffusibility of the soaked water may be deteriorated.
From the viewpoint of water permeability and suppression of transpiration from the ground, the average fiber diameter of the fibers constituting the meltblown nonwoven fabric is preferably 15 μm or less, and more preferably 2 to 15 μm. Further, from the viewpoint of uniform permeability by appropriately diffused water that has steeped than dry nonwoven fabric side to the ground, a basis weight of the meltblown nonwoven fabric is preferably ^{5~50g / m 2, 10~30g / m} 2 and more preferable.

The fibers constituting the meltblown nonwoven fabric used in the present invention are preferably ultrafine fibers made of a fiber-forming thermoplastic elastomer, such as polystyrene-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, polyurethane-based thermoplastic elastomer, polyester-based heat. Examples thereof include ultrafine fibers made of a plastic elastomer, a polyether thermoplastic elastomer, a polyamide thermoplastic elastomer, and the like. Of these, polyolefin elastomers are preferable, and ethylene-α-olefin copolymers are particularly preferably used.
The α-olefin copolymerized with ethylene is preferably an α-olefin having 3 to 10 carbon atoms.

  When an ethylene-α-olefin copolymer is used in the present invention, the melt flow rate (MFR: based on ASTM D1238) is preferably 5 to 200 g / 10 minutes, and more preferably 10 to 100 g / 10 minutes.

  In particular, in the present invention, it is preferable to use an ethylene-octene copolymer as the ethylene-α-olefin copolymer from the viewpoint of moisture diffusibility.

  Further, when the water absorbing / retaining sheet of the present invention is used for a herbicidal sheet, it is desirable to use a sheet having a light shielding property. It is preferable to use a melt blown nonwoven fabric composed of the contained original fibers. If the carbon black content is less than 0.1%, the light shielding effect is not sufficient, and the required herbicidal effect may not be obtained. On the other hand, if the content exceeds 10%, melt blow spinning may be difficult. The content of the carbon black is preferably 3 to 7% from the viewpoint of ensuring a balance between melt blown spinnability and light shielding properties.

  As the carbon black added to the resin constituting the melt blown nonwoven fabric, known ones such as channel black, furnace black, thermal black, acetylene black and lamp black can be used.

  The melt blown nonwoven fabric used in the present invention extrudes heat-melted resin from nozzles having orifices arranged in a row, ejects high-temperature air heated to the same temperature as the nozzles from a slit provided in the vicinity thereof, and spins from the orifices. It is obtained by making it thin by bringing it into contact with the molten resin, and laminating it on a collection surface arranged below the nozzle to form a sheet.

The dry nonwoven fabric used in the present invention contains polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) fiber, hydrophobic fiber, and heat-fusible fiber.
The PVA fiber used in the present invention is produced by solution spinning a spinning solution containing a PVA resin, specifically, wet spinning, dry wet spinning, or dry spinning. Solvents used in the spinning dope include solvents conventionally used in the production of PVA fibers, such as dimethyl sulfoxide (DMSO), dimethylformamide, dimethylacetamide, water, or polyvalent such as glycerin, ethylene glycol, triethylene glycol, etc. One kind or a combination of two or more kinds of alcohols, diethylenetriamine, rhodan salts and the like can be used. Among these, DMSO and water are particularly preferable from the viewpoints of availability and influence on environmental load. The resin concentration in the spinning dope varies depending on the composition of PVA resin, the degree of polymerization, and the solvent, but is generally in the range of 6 to 60% by mass. As long as the effects of the present invention are not impaired, additives such as antioxidants, antifreezing agents, pH adjusting agents, concealing agents, coloring agents, and oils are added to the spinning dope according to the purpose in addition to the PVA resin. Etc. may be included.

  The PVA fiber obtained by the solution spinning described above may be subjected to a stretching heat treatment in order to improve the crystallinity and orientation. The stretching heat treatment condition is generally 210 ° C. or higher, preferably 220 ° C. to 260 ° C., and stretched at a total stretching ratio of 8 times or more, preferably 10 to 25 times. Then, since the crystallinity degree and orientation degree of a fiber increase and the mechanical property of a fiber improves remarkably, it is preferable. In addition, the PVA fiber may be subjected to an acetalization treatment or other cross-linking treatment that is generally performed for PVA fibers for the purpose of improving hot water resistance, if necessary.

  The cross-sectional shape of the PVA fiber is not particularly limited, and may be, for example, a round cross section, a modified cross section, a polygonal cross section, or the like. Further, the single fiber fineness of the PVA fiber is not particularly limited, but is preferably 1 to 10 dtex, more preferably 1 to 7 dtex, and still more preferably 1 to 1 dtex from the viewpoint of the mechanical properties, water absorption, water retention balance, and the like of the nonwoven fabric. 5 dtex. On the other hand, the average fiber length of the PVA fibers is preferably 20 to 70 mm, more preferably 25 to 60 mm.

  The hydrophobic fiber constituting the dry nonwoven fabric used in the present invention refers to a fiber having an official moisture content of less than 5% in a standard state (20 ° C., 65% RH) and a melting point of 160 ° C. or more. Polyester fiber, polyolefin fiber, acrylic fiber, and the like, among which polyester fiber, particularly polyethylene terephthalate fiber is preferable.

The cross-sectional shape of the hydrophobic fiber is not particularly limited. For example, various cross-sections such as a round cross section, an irregular cross section, a polygon cross section, a multilobal cross section, a hollow cross section, a V shape, a T shape, an H shape, and an array shape. Etc.
In addition, the single fiber fineness of the hydrophobic fiber is preferably 1 to 10 dtex, more preferably 1 to 7 dtex, and still more preferably 1 to 5 dtex, from the viewpoint of ensuring card passage and an appropriate non-woven fabric density. On the other hand, the average fiber length of the hydrophobic fiber is preferably 20 to 70 mm, more preferably 25 to 60 mm.

On the other hand, the kind of the heat-fusible fiber constituting the dry nonwoven fabric used in the present invention is not particularly limited, but it is desirable to use a fiber having a low melting point resin having a melting point of 150 ° C. or lower as one component, for example, the low melting point resin. A single component (for example, polyethylene fiber) or a high melting point resin (polyester resin, polyamide resin, etc.) as a core component, and a low melting point resin (for example, polyethylene resin, modified polyester resin) as a sheath component A core-sheath type composite fiber can be used.
Among these, from the viewpoint of excellent weather resistance, a heat-fusible fiber made of a polyester resin is preferable, and it is particularly preferable to use a core-sheath type composite fiber in which the core component is polyethylene terephthalate and the sheath component is a modified polyester.
In addition, the single fiber fineness of the heat-fusible fiber is preferably 1 to 10 dtex, more preferably 1 to 7 dtex, and still more preferably 1 to 5 dtex, from the viewpoints of card passability and ensuring adhesion with a melt blown nonwoven fabric. is there. On the other hand, the average fiber length is preferably 20 to 70 mm, more preferably 25 to 65 mm.

In the dry nonwoven fabric used in the present invention, the above-described PVA fiber, hydrophobic fiber, and heat-fusible fiber are preferably blended in a ratio of 6 to 81% by mass: 54 to 9% by mass: 40 to 10% by mass, respectively. . By setting it as the above-mentioned ratio, it becomes possible to ensure an excellent balance between water absorption and water permeability, and good thermal adhesion with the above-described melt-blown nonwoven fabric improves sheet strength.
In particular, when used for grass protection sheets, etc., if the water permeability is low, it will flow from the surface of the sheet even if it is sprinkled. There is a risk that vegetables will die. In other words, it is necessary to quickly absorb moisture at the sprayed portion.
Moreover, the water | moisture content absorbed by the ground needs to be kept moderately and to be gradually dehumidified. Sheets that are unlikely to release moisture may have excessive moisture and cause roots such as vegetables to rot. On the other hand, if the moisture-releasing property is high, the moisture becomes insufficient, and the vegetables may die.
In this invention, the said subject can be solved by using the nonwoven fabric of the said structure as a dry-type nonwoven fabric.
The ratio of PVA fiber, hydrophobic fiber, and heat-fusible fiber is more preferably 30 to 55% by mass: 45 to 30% by mass: 25 to 15% by mass.

The dry nonwoven fabric can be produced by a known method. For example, the above short fibers are carded to obtain a short fiber web. As the short fiber web, parallel, random, semi-random, cross web, and the like can be used, and a semi-random web is particularly preferable.
The basis weight of the dry nonwoven fabric obtained by the above method is preferably 15 to 100 g / m ² , more preferably 20 to 70 g / m ² .

  The method for producing the water-absorbing / water-retaining sheet of the present invention is not particularly limited, and any method can be used as long as the melt-blown nonwoven fabric and the dry nonwoven fabric can be satisfactorily heat-bonded. Can be manufactured. Moreover, after entanglement of both by mechanical entanglement such as needle punching or water flow entanglement, the constituent fibers may be heat-sealed by heat treatment. Among these, hydroentanglement and embossing are preferably employed because they can be manufactured with high productivity.

  When embossing is performed, the embossed pattern is preferably a point embossed pattern rather than a continuous pattern from the viewpoint of ensuring water absorption, and the crimping area ratio is 5 to 40%, preferably 10 to 30%. If the crimping area exceeds 40%, the water absorption amount (water absorption speed) may be inferior. Conversely, if the area ratio is too low, the sheet strength may be insufficient.

Basis weight of the water-water retention sheet of the present invention thus obtained is preferably 30 to 250 g / ^{m 2,} more preferably from 40~150g / ^{m 2.} In addition, the water-absorbing / water-retaining sheet of the present invention preferably has a three-layer structure in which a dry nonwoven fabric is laminated on both surfaces of a melt-blown nonwoven fabric from the viewpoint of ensuring better water absorption and water retention.

The water-absorbing / retaining sheet of the present invention thus obtained preferably has a water permeability of 70% or more and a transpiration rate of 3 to 15 g / day, more preferably a water permeability of 80% or more and a transpiration property. 5 to 13 g / day. If the water permeability is too low, water may flow on the sheet surface and water may not penetrate into the necessary part.
Also, if the transpiration is too low, soil may rot due to moisture, gas escape from the ground may be poor, roots of rapeseed trees may be spoiled, and growth may be poor. Conversely, if the transpiration is too high, water shortage may occur.
In addition, the water permeability and transpiration | evaporation said by this invention are measured by the method mentioned later.

  Further, when using the water-absorbing / water-retaining sheet of the present invention as a herbicidal sheet, it is desirable to have a light-shielding property to prevent weed germination, specifically, a light-shielding rate of 90% or more, preferably 92% or more, more preferably 95% or more. The light shielding rate referred to in the present invention is measured by the method described later.

  The water-absorbing / water-retaining sheet of the present invention is particularly useful as a herbicidal sheet, but is not limited thereto, and can also be applied to uses such as fruit tree multi-sheets, seedling sheets, fruit vegetable multi-sheets. In addition, the water-absorbing / water-retaining sheet of the present invention is excellent in water permeability and water absorption, and emits moisture appropriately, so that when used as the above-described various sheets, the temperature change of the coated ground is small. There is.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these Examples at all. In addition, each physical property value in a present Example was measured with the following method.

(Weight, thickness, density)
The thickness (mm) corresponding to one sample was calculated by stacking four samples cut into 30 cm squares and making the thickness measured under 12 gf / cm ² load 1/4. Furthermore, the mass of the same sample (30 cm square × 4 sheets) was measured to determine the basis weight (g / m ² ) per sheet. Further, the apparent density (g / cm ³ ) was obtained by dividing the basis weight by the thickness.

(Average fiber diameter)
Using a scanning electron microscope (SEM), take a photograph of the surface of the nonwoven fabric magnified 1000 times, draw two diagonal lines on this photograph, and calculate the value obtained by converting the thickness of the fiber that intersects the diagonal line into a magnification. Using. And the average value of 50 of these fibers was made into the average fiber diameter.

(Light shielding)
The light shielding rate (%) was measured according to JIS L1906 5.10 (light shielding property and light projecting property). The illuminance of the light source was adjusted to 1000 lx.

(Water permeability)
The water permeability was measured by the method shown in FIG.
First, a 30 cm × 62 cm grid net 1 (net diameter 1 mm diameter, hole interval 3.5 cm) was arranged at an angle of 30 ° with respect to the ground. Next, a sample 2 (sheet) having a width of 30 cm and a length of 40 cm was placed on the lattice net. At this time, the receiving tank (I) 3 was installed immediately below the sample, and the receiving tank (II) 4 was installed in the vicinity of the portion where the lattice net and the ground contact.
A beaker 5 containing 500 g of water was prepared, water was poured from a position 3 cm high from the upper end of the sample over 20 seconds, and then left for 1 minute.
Next, the amount of water that fell into the receiving tank (I) (water permeability; g), the amount of water absorbed into the sample (water retention amount; g), and the amount of water that fell into the receiving tank (II), that is, it did not fall into the receiving tank (I), and Also, the amount of water that flowed out without being absorbed (flow amount; g) was measured.
A value (%) obtained by dividing the total amount of water permeability and water retention by 500 g was defined as water permeability (water permeability).
The same measurement was performed three times, and the results were recorded for each. The interval between each measurement was 5 minutes.
The higher the water permeability value, the better the water permeability.

(Transpiration)
After putting 300 g of water in a 500 cc beaker (diameter 10 cm) and covering a 15 cm × 15 cm sample (sheet) so as to cover the spout of the beaker, the vicinity of the spout was bound with a rubber band and the mass was measured.
This beaker was placed in a thermo-hygrostat (“Platinum Rainbow PR-1S” manufactured by Tabai Espec Co., Ltd.), and the mass was measured every 24 hours under the conditions of 40 ° C. and 60% humidity to determine the amount of water evaporation. The measurement time was 5 days (120 hours), and the total amount of evaporated water was divided by the measurement time to obtain transpiration.
Transpiration (g / day) = moisture evaporation (g) / 5 (day)
In addition, the transpiration | evaporation property at the time of measuring without covering a sample to a beaker was 43 g / day.

(Ground temperature measurement)
A sample (sheet) of 1 m ² was put on the soil ground, and a thermocouple for heat measurement was inserted into the center of the soil from the ground to a point 5 cm underground. The ground temperature was measured every 5 minutes for 72 hours using a temperature recorder (manufactured by Keyence Corporation, “NR-1000”), and the maximum temperature and the minimum temperature of the ground temperature during the measurement period were recorded. The outside temperature (maximum temperature and minimum temperature) during the measurement period is as shown in Table 2.

The following were prepared as raw fiber and raw nonwoven fabric, respectively.
[Fiber A]: Polyvinyl alcohol fiber (manufactured by Kuraray Co., Ltd., “Kuraron K-II EQ0”) 1.7 dtex × 38 mm
[Fiber B]: Polyethylene terephthalate fiber (manufactured by Teijin Limited, “TT04L”) 1.7 dtex × 44 mm
[Fiber C]: Heat-sealable fiber (core: polyethylene terephthalate / sheath: core-sheath type composite fiber which is a copolyester, sheath component melting point 110 ° C., manufactured by Teijin Ltd., “TT04C2”) 2.2 dtex × 51 mm
[Nonwoven fabric D] A melt blown nonwoven fabric having an average fiber diameter of 7 μm and a basis weight of 20 g / m ² was produced using an ethylene-octene copolymer (manufactured by Dow Chemical Company, “engage”, MFR: 30 g / 10 min). In addition, carbon black was added to the copolymer so that the content was 5% by mass in the constituent fibers of the melt blown nonwoven fabric.

40% by mass of polyvinyl alcohol fiber (fiber A), 40% by mass of polyethylene terephthalate fiber (fiber B), 20% by mass of heat-fusible fiber (fiber C), and a semi-random web having a basis weight of 30 g / m ² Manufactured to obtain a dry nonwoven fabric.
Next, after laminating the obtained dry nonwoven fabric on both sides of the melt blown nonwoven fabric (nonwoven fabric D), a water stream was sprayed on the three-layer laminate to perform an entanglement treatment. In addition, the hydroentanglement process used the nozzle in which the orifice of 0.1 mm in diameter was provided for every 0.6 mm space | interval in the width direction of the web, and was entangled by injecting on both sides with water pressure 3MPa and 5MPa, respectively.
After the entanglement treatment, drying was performed at 130 ° C. with a cylinder dryer to obtain the water absorbing / retaining sheet of the present invention. The results are shown in Tables 1 and 2.

A dry nonwoven fabric and a meltblown nonwoven fabric similar to those used in Example 1 were prepared, and three-layer lamination and hydroentanglement treatment were performed.
Next, a black pigment (Toyo Ink, “WS-Black K-7”) and an acrylic binder (Nihon Carbide, “FX-582”) are mixed at a mass ratio of 15:85, The mixture was applied to the entire surface of the sheet with a gravure roll of 3.2 g / m ² .
Subsequently, it dried at 130 degreeC with the cylinder dryer, and obtained the water absorption and water retention sheet | seat of this invention whose sheet | seat surface is black. The results are shown in Tables 1 and 2.

A dry nonwoven fabric and a meltblown nonwoven fabric similar to those used in Example 1 were prepared, and three layers were laminated to obtain a laminate. The thus obtained laminate, heat embossing roll with (bonding area ratio of 26%, the point area 0.51 cm ² / number, number of points 51 pieces / cm ^2), roll temperature 130 ° C., the linear pressure 30kg / cm Then, a heat embossing treatment was performed to obtain a water absorbing / retaining sheet of the present invention. The results are shown in Tables 1 and 2.

After using the same raw material fiber as that used in Example 1 to produce a semi-random web at the same mixing rate, a water stream was jetted to perform an entanglement treatment. In addition, the hydroentanglement treatment uses a nozzle in which an orifice having a diameter of 0.1 mm is provided at intervals of 0.6 mm in the width direction of the web, and is entangled by spraying the front and back at a water pressure of 3 MPa and 5 MPa, respectively, and has a basis weight of 30 g / m. ² hydroentangled nonwoven fabric was obtained.
On the other hand, the melt blown nonwoven fabric (nonwoven fabric D) used in Example 1 was prepared, and the obtained water-entangled nonwoven fabric was laminated on both sides of the melt blown nonwoven fabric to form a three-layer laminate.
The thus obtained laminate, heat embossing roll with (bonding area ratio of 26%, the point area 0.51 cm ² / number, number of points 51 pieces / cm ^2), roll temperature 130 ° C., the linear pressure 30kg / cm Then, a heat embossing treatment was performed to obtain a water absorbing / retaining sheet of the present invention. The results are shown in Tables 1 and 2.

Comparative Example 1
80% by mass of polyethylene terephthalate fiber (fiber B) and 20% by mass of heat-fusible fiber (fiber C) were mixed to produce a semi-random web having a basis weight of 30 g / m ² to obtain a dry nonwoven fabric.
Next, after laminating the obtained dry nonwoven fabric on both surfaces of the meltblown nonwoven fabric (nonwoven fabric D), a water stream was sprayed onto the laminate to perform an entanglement treatment. In addition, the hydroentanglement process used the nozzle in which the orifice of 0.1 mm in diameter was provided for every 0.6 mm space | interval in the width direction of the web, and was entangled by injecting on both sides with water pressure 3MPa and 5MPa, respectively.
After the entanglement treatment, drying was performed at 130 ° C. with a cylinder dryer to obtain a water absorption / water retention sheet. The results are shown in Tables 1 and 2.

Comparative Example 2
40% by mass of polyvinyl alcohol fiber (fiber A), 40% by mass of polyethylene terephthalate fiber (fiber B), 20% by mass of heat-fusible fiber (fiber C), and a semi-random web having a basis weight of 80 g / m ² Manufactured. Subsequently, a water flow was sprayed on this web, and the entanglement process was performed. In addition, the hydroentanglement process used the nozzle in which the orifice of 0.1 mm in diameter was provided for every 0.6 mm space | interval in the width direction of the web, and was entangled by injecting on both sides with water pressure 3MPa and 5MPa, respectively.
After the entanglement treatment, drying was performed at 130 ° C. with a cylinder dryer to obtain a water absorption / water retention sheet. The results are shown in Tables 1 and 2.

Comparative Example 3
The same evaluation as in the example was performed using an agricultural polyethylene black film (manufactured by Yasushi Watanabe, “Pokapoka Sheet”, thickness 30 μm). The results are shown in Tables 1 and 2.

  Using the water-absorbing / water-retaining sheet obtained in the above examples as a herbicidal sheet and cultivating tomatoes, weeds were hardly sprouting on the part where the herbicidal sheet was laid, and tomato growth was also good. It was. Good results were also obtained for the cultivation of cucumbers and house oranges.

The schematic diagram which shows the apparatus for measuring the water permeability in this invention.

Explanation of symbols

1: Grid net 2: Sample 3: Receiving tank (I)
4: Receiving tank (II)
5: Beaker

Claims (6)

A water-absorbing / water-retaining sheet obtained by laminating a dry nonwoven fabric containing polyvinyl alcohol fibers, hydrophobic fibers, and heat-fusible fibers on at least one surface of a meltblown nonwoven fabric. The water absorption / water retention according to claim 1, wherein a mixing ratio of polyvinyl alcohol fiber, hydrophobic fiber, and heat-fusible fiber constituting the dry nonwoven fabric is 6 to 81 mass%: 54 to 9 mass%: 40 to 10 mass%. Sheet. The water-absorbing / water-retaining sheet according to claim 1 or 2, wherein the fibers constituting the melt blown nonwoven fabric are made of an olefin elastomer resin. The water-absorbing / water-retaining sheet according to any one of claims 1 to 3, wherein the melt-blown nonwoven fabric is composed of an original fiber containing 0.1 to 10% of carbon black with respect to the fiber mass. The water absorption / water retention sheet according to any one of claims 1 to 4, wherein the water permeability is 70% or more and the transpiration is 3 to 15 g / day. The weed prevention sheet | seat which uses the water absorption and water retention sheet | seat of any one of Claims 1-5.

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