JP5637592B2 - Artificial grass structure - Google Patents

Description

  The present invention relates to an artificial turf structure laid on, for example, a soccer field, and more specifically to an artificial turf structure that suppresses the temperature increase of the artificial turf and reduces the burden on the player.

  For example, as shown in Patent Document 1, a long pile artificial turf is made by filling a filler between piles of a base fabric in which a pile longer than a normal artificial turf is planted, and has an elasticity characteristic close to that of natural turf. As an artificial turf surface, it is widely used in various sports facilities such as soccer, rugby and baseball fields.

  As this type of artificial turf filler, for example, rubber chips (crushed products of industrial rubber such as waste tires and EPDM) and elastic elastomers of thermoplastic elastomers (EPDM and PE-based elastic resins) are used. It is done.

  By the way, since rubber chips such as waste tires are colored black with carbon, they easily absorb sunlight, and the surface temperature of artificial turf may be 60 ° C. or higher under hot weather such as summer.

  For this reason, exercise on artificial grass in the summer is a heavy load on the player and the comfort is deteriorated. Therefore, most of this type of artificial turf is designed to lower the surface temperature by watering before playing. However, watering is only a temporary treatment, and a sustained effect of several hours was not obtained.

  Thus, as a method for more efficiently using the heat of vaporization by watering, for example, there is Patent Document 2. Patent Document 2 discloses a method of containing a water-absorbing material in a part of a base fabric of artificial turf, storing water in the water-absorbing material, and suppressing a temperature rise due to heat of vaporization for a long time. . As for the water-absorbing resin, the measuring method of the water absorption amount and the water absorption speed is also defined by Japanese Industrial Standards (JIS) (Non-Patent Documents 1 and 2), and many types are now available from various companies including the past.

  However, since the method described in Patent Document 2 contains a water-absorbing material in the base fabric, the temperature suppression effect on the artificial turf surface (that is, the surface of the filler) that has the highest temperature cannot be expected so much. . In particular, the long pile artificial turf has a pile length (length from the base fabric to the pile tip) as long as 30 mm or more, so it is considered that there is almost no temperature suppression effect on the surface of the artificial turf.

  In addition, regarding artificial turf and water absorbent resin, Patent Document 3 discloses that artificial turf containing sand has rubber or synthetic resin powder containing water absorbent resin in the lower layer so that the sand does not harden even when used for a long time. Disclosed are artificial grasses with sand dispersed on the upper layers. According to Patent Document 4, the maximum water absorption measured according to JIS K-6767 is 100 to 1000 times its own weight in response to a change in the surrounding humidity in order to prevent scratches and burns in an athletic field made of artificial grass. An artificial turf athletic stadium in which fine particles of water-absorbing resin that absorbs and releases moisture are dispersed is disclosed. Patent Document 5 also discloses the use of a water-absorbing resin for preventing the elastic filler (rubber) from sagging. These are also considered to have almost no temperature suppression effect on the surface of the artificial turf due to the difference described later.

JP 2003-34906 A JP 2007-126850 A JP-A-3-72102 JP-A-6-33411 JP 2002-294620 A

Japanese Industrial Standard (JIS) K7223-1996 Japanese Industrial Standard (JIS) K7224-1996

  Therefore, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide an artificial turf structure that can suppress a temperature rise for a long time and maintain a comfortable play. It is in.

In order to solve the above problems, the present inventors have intensively studied and found that the above problems can be solved by using an artificial turf having a specific structure, thereby completing the present invention. That is, the artificial turf structure according to the present invention is an artificial turf structure in which a filler is filled between piles of an artificial turf having a pile length of 30 mm or more, and the unit per unit area defined by the following formula. In order to satisfy the hydraulic power of 50 to 2000 [g / m ² ], a water absorbent resin whose pure water absorption magnification is 3 to 150 [g / g] as measured by a measurement method based on (JIS) K7223 , An artificial turf structure characterized in that the content per unit area is 0.5 to 100 [g / m ² ] and is included in the filler. However, the water retention capacity per unit area is defined by the following formula.
(Water retention capacity per unit area) = (pure water absorption ratio) x (content per unit area)

The artificial turf structure cooling method of the present invention is a method for cooling an artificial turf structure in which a filler is filled between piles of an artificial turf having a pile length of 30 mm or more, and is defined by the following formula: In order to satisfy the water holding power per unit area of 50 to 2000 [g / m ² ] , the pure water absorption magnification is 3 to 150 [g / g] with a measured value according to the measurement method based on (JIS) K7223 . In an artificial turf structure in which a certain water-absorbing resin is contained in the filler with a content per unit area of 0.5 to 100 [g / m ² ], the water-absorbing resin is added to the upper layer portion of the filler. It is a method for cooling an artificial turf structure characterized by being sprayed on the surface. However, the water retention capacity per unit area is defined by the following formula.
(Water retention capacity per unit area) = (pure water absorption ratio) x (content per unit area)

  Preferably, the artificial turf structure has a weight average particle diameter of 0.1 to 2.0 mm.

Preferably, it is an artificial turf structure in which the water-absorbing resin is present in the surface layer portion of the filler. Moreover, it is preferable that the protruding height of the pile from the surface of the filler to the tip of the pile is 10 mm or more.

  According to the present invention, by including a predetermined amount of water-absorbing resin in a part of the filler, the water can be efficiently retained for a long time without impairing the properties and playability of the artificial turf. The temperature rise can be suppressed over the entire range.

FIG. 1 is a schematic diagram showing an artificial turf structure according to an embodiment of the present invention.

  Hereinafter, the present invention will be described. However, the scope of the present invention is not limited to these descriptions, and other than the following examples, the present invention can be appropriately modified and implemented without departing from the scope of the present invention. is there. Specifically, the present invention is not limited to the following embodiments, and various modifications are possible within the scope of the claims, and technical means disclosed in different embodiments are appropriately combined. Embodiments obtained in this manner are also included in the technical scope of the present invention. In this specification, “mass” and “weight” are synonymous. Further, “X to Y” indicating a range means “X or more and Y or less”.

  As shown in FIG. 1, the artificial turf structure 1 has an artificial turf 3 laid on a base 2, and a granular material 5 is filled between piles 4 of the artificial turf 3. In this embodiment, the base 2 uses a simple pavement surface that leveles the ground flat, but in addition to this, gravel may be spread, or an existing pavement surface paved with asphalt or the like is used. Also good.

  Furthermore, an elastic pavement or the like may be provided on the base 2. In the present invention, the configuration of the base 2 can be changed according to the specifications and is an optional matter.

  In the artificial turf 3, piles 4 are planted on a base cloth 31 at a predetermined interval. For the base fabric 31, for example, a thermoplastic resin such as polypropylene or polyethylene is preferably selected. In consideration of recyclability, low-density polyethylene with good meltability is more preferable.

  In this example, the base fabric 31 is a plain woven fabric made of synthetic resin such as polypropylene or polyethylene, but in addition to this, even if a cotton fabric of synthetic resin is planted on the plain woven fabric by punching Good. In addition, although the color of the base fabric 31 is arbitrarily determined according to a specification, when it is remade to a granular material, it may be colored in colors other than black so that it may be hard to absorb the heat of the sun. preferable.

  Various artificial turf can be used as the artificial turf of the present invention, but it is preferably applied to long pile artificial turf. The pile 4 is preferably a so-called long pile in which the pile length H1 from the surface to the tip of the base fabric 31 is 30 mm or more, preferably 40 to 75 mm. The pile 4 is preferably selected from thermoplastic resins such as polypropylene and polyethylene, but in view of recyclability, low-density polyethylene with good meltability is more preferable. The pile 4 is colored green, but any color other than black is used.

The pile 4 may be a bundle of a plurality of monotape yarns or monofilament yarns, or a strip-like split yarn. In this example, the pile 4 has a thickness of 8000 to 16000 dtex, and is planted on the base fabric 31 with a planting amount of 1000 to 2000 [g / m ² ].

  Further, a backing material 32 (backing material) is uniformly applied to the back surface of the base fabric 31 in order to prevent the tufted pile 4 from falling off. For the backing material 32, for example, a thermosetting resin such as SBR latex or urethane is used. If necessary, an extender such as calcium carbonate is added.

In this example, the backing material 32 is uniformly applied so that the application amount is 600 to 800 [g / m ² ] (when dried). The backing material 32 is preferably colored in a color other than black in consideration of the color at the time of reproduction of the granular material to be reproduced.

  In the present invention, the base fabric 31 and the pile 4 are made of a thermoplastic resin such as polypropylene and polyethylene that can be easily heated and melted in consideration of recyclability, but may be made of other materials. The backing material 5 is made of a thermosetting resin such as SBR latex in consideration of workability and the like, but this can be arbitrarily changed according to the specifications.

  A filler 5 is filled between the piles 4 of the artificial turf 3 thus created. In this example, the filler 5 is made of a mixture of elastic granular material and hard granular material, and is filled so as to have a predetermined thickness. The filler 5 may have a two-layer structure of an upper layer made of only elastic granular material and a lower layer made of only hard granular material, or may be a single layer structure of either elastic or hard granular material.

The layer thickness of the filler 5 is arbitrarily selected depending on the required elasticity, but in order to prevent the filler 5 from flowing out and scattering, the pile protrusion height H2 (from the surface of the filler layer to the tip of the pile) It is preferable that the thickness is 10 mm or more.

  The elastic granular material is preferably a recycled product of a waste rubber product such as a waste tire. Moreover, it is preferable that 0.3-3 mm is a main component (especially 90 weight% or more) as for the particle size (upper and lower limits prescribed | regulated by standard sieve classification) of an elastic granular material. That is, if many coarse particles having a particle size exceeding 3 mm are contained, the elastic particles are not well-contained between the piles. If many fine particles less than 0.3 mm are contained, they may be scattered by the wind or run out by rainfall.

  The hard granular material may be stones in addition to various ceramics, and quartz sand is particularly suitable. Moreover, it is preferable that 0.1-1.2 mm is a main component (50 weight% or more, Furthermore, 70 weight% or more) as for the particle size (upper and lower limits prescribed | regulated by standard sieve classification) of a hard granular material. That is, if there are many coarse particles having a particle size exceeding 1.2 mm and fine particles less than 0.1 mm, they are easily separated even when mixed with elastic particles, and the separated hard particles are on the lower layer side. Therefore, the elasticity of the whole artificial turf will be reduced.

  The filler 5 further includes a water absorbent resin 6 for temporarily storing the sprinkled water. The water-absorbing resin 6 (water-absorbing polymer) is made of various water-absorbing resins such as polyacrylic acid type, polysaccharide type, polyvinyl alcohol type, polyacrylic acid amide type, and is formed in a predetermined shape. Of these, polyacrylic acid-based water-absorbing resins are most preferred from the standpoints of physical properties and cost.

  The water-absorbing resin 6 contained in the artificial turf structure 1 of the present invention is not particularly limited, but from the viewpoint of water-absorbing properties, it optionally contains a graft component, and acrylic acid and / or a salt thereof (neutralized product) (hereinafter referred to as “the water-absorbing resin”). A polyacrylic acid water-absorbing resin having an internal cross-linked structure obtained by polymerizing a monomer mainly composed of “acrylic acid (salt)” is preferable. Furthermore, the surface of the water absorbent resin 6 may have an organic secondary cross-linked structure. (Hereinafter, simply referred to as “water absorbent resin 6”.)

  As the main raw material of the water-absorbent resin 6, that is, an unsaturated monomer (hereinafter simply referred to as “monomer”), it is preferable to use acrylic acid (salt) as a main component. A monomer may be used in combination.

  The acrylate ratio (neutralization rate) in the acrylic acid monomer is preferably 10 to 95 mol%, more preferably 30 to 90 mol%, and 60 to 80 mol%. Most preferred. If the acrylate ratio is less than 10 mol%, the pH of the water-absorbing gel will be too low, and if the acrylate is greater than 95 mol%, the pH of the water-absorbing gel will be too high. This is not preferable. The pH of the water-absorbing gel is preferably from 5 to 7 in terms of irritation to the skin. The pH of the water-absorbing gel can be measured according to the test method ERT400.2-02 recommended by EDANA.

  Here, “EDANA” is an abbreviation for European Disposables and Nonwovens Associations, and “ERT” is an abbreviation for a method for measuring water-absorbent resin (ERT / EDANA Recommended Test Methods) of European standards (almost world standards). is there.

  The water-absorbent resin 6 essentially has a crosslinked structure, and the form of crosslinking may be a self-crosslinking type that does not use a crosslinking monomer, or two or more polymerizable unsaturated groups in one molecule. Copolymer of 0.001 to 30% by weight, preferably 0.01 to 15% by weight of a crosslinkable monomer having a group or two or more reactive groups (hereinafter simply referred to as “internal crosslinking agent”). Alternatively, it may be reacted. In the present invention, the internal crosslinking agent is not particularly limited.

  The water absorbent resin 6 is obtained by polymerizing the above monomers. In this example, a radical polymerization initiator is used as the polymerization initiator used in the polymerization, but in the present invention, the polymerization initiator is not particularly limited.

  Further, as a polymerization method for obtaining the water absorbent resin 6, from the viewpoint of water absorption performance of the water absorbent resin 6 and ease of polymerization control, aqueous polymerization or reverse phase suspension polymerization using the above monomer as an aqueous solution is preferable. However, the polymerization method is not particularly limited in the present invention.

  The shape of the water-absorbent resin may be a gel or a fiber, but preferably a powder, further a crushed shape, a spherical shape, etc. can be used, but an irregularly crushed shape that is likely to stay in the upper layer of the artificial turf filler. Particles are preferred.

  The water-containing gel-like polymer obtained by the above polymerization process may be dried as it is, but may be dried after being chopped using a gel grinder if necessary. The water-absorbent resin 6 obtained in the drying step may be subjected to a pulverization and / or classification step in order to control the particle size as necessary according to the purpose. These methods are disclosed in, for example, International Publication No. 2004/69915. Moreover, you may further provide processes, such as a surface bridge | crosslinking process, a granulation process, a fine powder removal process, and a fine powder recycling process, as needed.

  In this example, the water-absorbing resin 6 is formed by molding a polyacrylic acid-based water-absorbing resin mainly made of sodium acrylate into a granular shape (powder). And may be added with a weather resistance additive.

The water absorbent resin 6 according to the present invention has a pure water absorption ratio of 3 to 150 [g / g], preferably 4 to 130 [g / g], more preferably 5 to 120 [g / g], Furthermore, it should just be 6-90 [g / g], and a spraying form is not specifically limited. That is, it may be a dried product, a water-containing gel-like product that has been absorbed in advance, or an aqueous dispersion. The content per unit area is 0.5 to 100 [g / m ² ], preferably 1 to 90 [g / m ² ], more preferably 100% by weight in terms of solid content of the water absorbent resin. Is ^{2 to} 80 [g / m ² ]. Furthermore, the water holding capacity per unit area defined by the following formula is 50 to 2000 [g / m ² ], preferably 60 to 1500 [g / m ² ], more preferably 70 to 1000 [g / m. ² ]. The sprayed state of the water-absorbent resin may draw a pattern such as a stripe or dot, but is preferably sprayed uniformly.

  In addition, although the pure water absorption magnification of the water-absorbent resin generally marketed varies in its measuring method, it is usually 200 to 1000 [g / g]. More specifically, as a catalog value, Name Aqua Keep (manufactured by Sumitomo Seika); 200-1000 [g / g], trade name Sunwet (manufactured by Sanyo Kasei); 400-1000 [g / g], trade name Sumikagel (manufactured by Sumitomo Chemical); 500-700 [G / g], trade name Aqua reserve (manufactured by Nippon Synthetic Chemical); 250 to 800 [g / g].

  In addition, as a method for measuring the water absorption rate of a water absorbent resin, in Japanese Industrial Standard (JIS) K7223-1996, the water absorbent resin contained in a tea bag type bag is immersed in water and freely swollen, and then the bag is taken out of the water. A method of measuring weight after hanging and draining is disclosed. The water absorption ratio of the present invention is defined by the method of measuring the water absorption ratio by centrifuging (250 G, 3 minutes) rather than hanging the drainer. By the measurement method specified in this specification, pure water (30 minutes) The water-absorbing resin having a low water absorption ratio of 3 to 150 g / g is used after centrifugation.

  Regarding artificial turf and water-absorbent resin, Patent Document 3 (Japanese Patent Laid-Open No. 3-72102) describes sand or artificial turf containing rubber or water-absorbing resin so that sand does not harden even when used for a long time. Disclosed is an artificial turf containing sand in which a synthetic resin powder is dispersed in a lower layer and sand is dispersed in an upper layer. In this example, Patent Document 3 mixes a water-absorbent resin Aquakeep 10SH (polyacrylic acid, manufactured by Iron and Chemical Industries (currently, Sumitomo Seika)) with natural rubber. The water absorption ratio of Aqua Keep 10SH into pure water is a high magnification of 600 to 1000 g / g in the above catalog value, and Patent Document 3 discloses the water absorption ratio of the present invention with the low water absorption ratio (3 to 150 g / g in pure water). No resin is disclosed.

  Regarding artificial turf and water-absorbing resin, Patent Document 4 (Japanese Patent Laid-Open No. 6-33411) discloses a maximum water absorption amount measured according to JIS K-6767 in an athletic stadium made of artificial grass to prevent scratches and burns. Discloses an athletic stadium made of artificial turf that is 100 to 1000 times its own weight and sprayed with fine particles of a water absorbent resin that absorbs and releases moisture according to changes in ambient humidity.

  In this example, Patent Document 4 sprays a crosslinked polyacrylate having a particle size of 20 to 50 microns (manufactured by Sanyo Chemical Industries; Sunwet) as a water-absorbing resin. The sunwet used in this example (PATENT DOCUMENT 4 does not have a product number) has a high magnification of 400 to 1000 g / g in the above catalog value. For example, the catalog value of Sunwet IM-1000MPS has a center particle size of 20 to 50 μm. The water absorption rate for ion exchange is 1000 g / g. Therefore, Patent Document 4 (cross-linked polyacrylate having a particle size of 20 to 50 microns in the examples (manufactured by Sanyo Kasei Kogyo; using Sunwet)) has a low water absorption capacity (3 to 150 g / g in pure water) of the present invention. ) Is not disclosed at all.

  Furthermore, regarding artificial turf and a water-absorbing resin, Patent Document 5 (Japanese Patent Laid-Open No. 2002-294620) also discloses the use of a water-absorbing resin to prevent the elastic filler (rubber) from sagging. No. 5 does not disclose any water-absorbing resin of the present invention having a low water absorption ratio (3 to 150 g / g in pure water).

  In contrast to the above-mentioned Patent Documents 2 to 5, the water-absorbing resin having a low water absorption ratio of 3 to 150 g / g with respect to pure water essential in the present invention is crosslinked at the time of production (after polymerization or after polymerization) of the water-absorbing resin. The amount of the agent may be increased as appropriate to obtain a high crosslinking / low water absorption ratio, or a commercially available water absorbent resin may be further crosslinked.

  The water absorption capacity of the water-absorbing resin is often measured with physiological saline (0.9% -NaCl aqueous solution), and the water-absorbing resin generally used in commercially available diapers is the water absorption capacity with physiological saline. Is about 25 to 60 g / g, more preferably about 30 to 50 g / g. However, the water absorption ratio in pure water is about an order of magnitude higher (about 10 times the water absorption capacity in physiological saline) compared to the water absorption ratio in physiological saline. Although the water absorption ratio with respect to ion-exchanged water is 200 to 1000 g / g, the water-absorbent resin of the present invention is more pure than the general water-absorbent resins described in Patent Documents 2 to 5 and commercial water-absorbent resin catalogs. It is characterized by using a low water absorption rate of 3 to 150 g / g for water (an order of magnitude lower for physiological saline).

When the water retention capacity per unit area is less than 50 [g / m ² ], since the water retention capacity after water absorption is small, the temperature rise suppressing effect cannot be maintained for a long time. In addition, when the water retention capacity exceeds 2000 [g / m ² ], the amount of water-absorbing resin per unit area is large, and when the water-absorbing resin gels after watering, the surface between the artificial turf surface and the shoe sole It becomes slippery and the playability is impaired.

  The weight average particle diameter of the water absorbent resin 6 according to the present invention is 0.1 to 2.0 mm, preferably 0.2 to 1.8 mm, and more preferably 0.3 to 1.5 mm. When the weight average particle diameter is less than 0.1 mm, the water absorbent resin 6 falls from the gaps between the fillers 5 and the temperature suppression effect on the artificial turf surface may be reduced. On the other hand, when the weight average particle diameter exceeds 2.0 mm, it appears on the surface of the artificial turf, which is not preferable in appearance.

  In this embodiment, the water absorbent resin 6 is obtained by sieving the bulk material of the water absorbent resin 6 finely with a crusher or the like with a sieve having a mesh size of 0.1 to 2.0 mm and passing through the sieve. The water-absorbent resin powder that can be prepared is preferably used, and fine particles may be removed if necessary. Therefore, since it is only necessary to be able to pass through the sieve, the shape includes, for example, a powdery shape and a needle shape having a high aspect ratio in addition to the granular shape.

  Furthermore, it is desirable that the water absorbent resin 6 has a constant water absorption speed. As a guideline, the water absorption resin 6 can reach a predetermined water absorption rate by watering for about 1 minute by the method prescribed in the embodiment. preferable. That is, if the water absorption speed is low, water at the time of watering cannot be absorbed, and the effect of suppressing the temperature rise may be reduced, which is not preferable.

  As shown also in FIG. 1, it is preferable that the water absorbent resin 6 exists in the surface layer part of a filler. That is, the presence of the water-absorbing resin in the surface layer portion of the filler allows water to be retained near the surface of the artificial turf, so that the temperature rise suppression effect is the highest and the water absorption efficiency during watering is also good. .

  Next, specific examples of the present invention will be described together with comparative examples. First, a sample of a water absorbent resin was prepared by the following method.

[Production of water-absorbing resin]
As the water-absorbent resin contained in the artificial turf structure 1 of the present invention, by changing the reaction conditions such as the type and amount of the crosslinking agent during polymerization of the partially neutralized sodium acrylate aqueous solution having a neutralization rate of 60 mol%, Four types of irregularly crushed sodium polyacrylate (polyacrylic acid-based water-absorbing properties) having absorption ratios different from 12 [g / g], 64 [g / g], 150 [g / g] and 250 [g / g] Resin powder). Here, the method for measuring the water absorption magnification is calculated by putting a sample into a nonwoven fabric, attaching it to pure water, dehydrating the sample taken out, and comparing and measuring the weight before and after the water absorption.

(Measurement of water absorption rate)
The water absorption rate for each sample of the water absorbent resin was measured. In the measurement method, a mesh having an opening of 0.2 mm is attached to the bottom of a 20 cm × 20 cm wooden frame case, a 1 g water-absorbing resin sample is placed in the center, and 1 L of pure water is applied to the sample with a joro. After the application of pure water, the weight of each case is measured 1 minute later. By measuring the difference from the weight before measurement, the amount of water absorption per minute (water absorption rate) was obtained.

[Measurement of water absorption ratio]
Put 0.02g of water-absorbent resin uniformly in a bag made of unwoven cloth (60mm x 85mm), and after heat sealing, immerse it in 500mL pure water (electric conductivity 5 [μS / cm] or less) adjusted to 23 ° C. And allowed to stand. After 30 minutes, the bag was pulled up, drained with a centrifuge (250 G / 3 minutes), and the weight W2 [g] of the bag was measured. The same operation was performed without putting a sample, and the weight W1 [g] of the bag at that time was measured. From these weights W1 and W2, the water absorption capacity [g / g] was determined according to the following equation.
Water absorption ratio [g / g] = (W2-W1-sample weight) / (sample weight)

(Measurement of weight average particle diameter)
The water-absorbent resin was sieved with JIS standard sieves having openings of 5600 μm, 4750 μm, 3350 μm, 2800 μm, 2000 μm, 1400 μm, 1000 μm, 850 μm, 600 μm, 500 μm, 300 μm, 150 μm, and 45 μm, and the residual percentage R was plotted on logarithmic probability paper. . Thereby, the particle size corresponding to R = 50% by weight was read as the weight average particle size (D50).

  As a sieving method, 10 g of a water-absorbing resin was charged into the above JIS-Z8801-1 standard sieve (The IIDA TESTING SIEVE: inner diameter 80 mm) under conditions of room temperature (20 to 25 ° C.) and relative humidity 50% RH, and a low tap. Using a type sieve shaker (“ES-65 type sieve shaker” manufactured by Iida Seisakusho Co., Ltd .: rotation speed 230 rpm, impact number 130 rpm), the mixture was shaken for 10 minutes for classification.

Next, each evaluation test of each example and comparative example was performed.
[Evaluation test of temperature rise suppression effect]
A black rubber chip filler made of waste tire is filled in a 20 cm × 20 cm wooden frame with a thickness of 30 mm, and water-absorbing resin based on various setting conditions of Examples 1 to 7 and Comparative Examples 1 to 6 is sprayed on the surface layer. Create test soil. Next, after sufficient watering is performed on the test soil, light is irradiated from above with a projector, and the change in surface temperature is measured. The case where the surface temperature after the elapse of 3 hours from the start of irradiation was 55 ° C. or lower was rated as “◯”, and the case where the surface temperature was higher than 55 ° C. was evaluated as “X”.

[Evaluation test for playability]
A test artificial turf of 1 m × 3 m is prepared, and a test soil is prepared by spraying water-absorbing resin based on various setting conditions of Examples 1 to 7 and Comparative Examples 1 to 6 on the surface. Next, after watering the test soil sufficiently, three testers run on each test soil to make turns, etc. Compared to the case where water-absorbent resin is not sprayed, such as slipperiness. The presence or absence of an influence on playability was evaluated. As an evaluation method, if playability such as slipperiness or uncomfortable feeling is affected, ×, if not, ○, if any one of the three evaluators has ×, playability is × did.
Further, from these evaluation tests, a comprehensive evaluation was performed with both marked as “good” when “good” and “good” when either of them was “good”.
Below, the specification of each Example and a comparative example, each evaluation result, and its comprehensive evaluation are shown.

Example 1
[Water absorption ratio A] 12 [g / g]
[Spreading amount B] 15 [g / m ² ]
[A × B] 180 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ○
[Comprehensive evaluation] ○

Example 2
[Water absorption ratio A] 12 [g / g]
[Spreading amount B] 30 [g / m ² ]
[A × B] 360 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ○
[Comprehensive evaluation] ○

Example 3
[Water absorption ratio A] 12 [g / g]
[Spreading amount B] 100 [g / m ² ]
[A × B] 1200 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ○
[Comprehensive evaluation] ○

Example 4
[Water absorption ratio A] 64 [g / g]
[Spreading amount B] 1 [g / m ² ]
[A × B] 64 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ○
[Comprehensive evaluation] ○

Example 5
[Water absorption ratio A] 64 [g / g]
[Spreading amount B] 15 [g / m ² ]
[A × B] 960 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ○
[Comprehensive evaluation] ○

Example 6
[Water absorption ratio A] 64 [g / g]
[Spreading amount B] 30 [g / m ² ]
[A × B] 1920 [g / m ² ]
Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ○
[Comprehensive evaluation] ○

Example 7
[Water absorption ratio A] 150 [g / g]
[Spreading amount B] 1 [g / m ² ]
[A × B] 150 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ○
[Comprehensive evaluation] ○

<Comparative example 1>
[Water absorption ratio A] 0 [g / g]
[Spreading amount B] 0 [g / m ² ]
[A × B] 0 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect] ×
[Playability evaluation] ○
[Comprehensive evaluation] ×

<Comparative example 2>
[Water absorption ratio A] 12 [g / g]
[Spreading amount B] 1 [g / m ² ]
[A × B] 12 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect] ×
[Playability evaluation] ○
[Comprehensive evaluation] ×

<Comparative Example 3>
[Water absorption ratio A] 12 [g / g]
[Spreading amount B] 200 [g / m ² ]
[A × B] 2400 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ×
[Comprehensive evaluation] ×

<Comparative example 4>
[Water absorption ratio A] 64 [g / g]
[Spreading amount B] 100 [g / m ² ]
[A × B] 6400 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ×
[Comprehensive evaluation] ×

<Comparative Example 5>
[Water absorption ratio A] 150 [g / g]
[Spreading amount B] 15 [g / m ² ]
[A × B] 22500 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ×
[Comprehensive evaluation] ×

<Comparative Example 6>
[Water absorption ratio A] 250 [g / g]
[Spreading amount B] 1 [g / m ² ]
[A × B] 250 [g / m ² ]
[Weight average particle size] 1.0 mm
[Temperature rise suppression effect]
[Playability evaluation] ×
[Comprehensive evaluation] ×

  Table 1 shows the specifications of the water-absorbent resins of Examples and Comparative Examples and a summary of the evaluation results.

According to this, the following knowledge was obtained. Examples 1 to 7 (shaded portions in Table 1) satisfying a water retention per unit area of 50 to 2000 [g / m ² ] using a water absorbing resin having a low water absorption ratio are filled with a water absorbing resin. Even if sprayed on the surface layer, the playability is not affected and the temperature rise suppressing effect is the best. In other words, this is the most preferred embodiment in the present invention. On the other hand, as in the comparative example, when the water holding power per unit area deviates from 50 to 2000 [g / m ² ], or a water absorption ratio of 250 g / g corresponding to a conventional general commercially available water absorbent resin. This water absorbent resin does not give satisfactory results.

DESCRIPTION OF SYMBOLS 1 Artificial turf structure 2 Underlayer 3 Artificial turf 4 Pile 5 Filler 6 Water absorbing resin

Claims (5)

An artificial turf structure in which a filler is filled between piles of artificial turf having a pile length of 30 mm or more ,
In order to satisfy the water holding power per unit area defined by the following formula of 50 to 2000 [g / m ² ] , the pure water absorption ratio is 3 to 150 [ g / g], the artificial turf structure is characterized in that a water-absorbent resin having a content per unit area of 0.5 to 100 [g / m ² ] is included in the filler.
However, the water retention capacity per unit area is defined by the following formula.
(Water retention capacity per unit area) = (pure water absorption ratio) x (content per unit area)   The artificial turf structure according to claim 1, wherein the water-absorbent resin has a weight average particle diameter of 0.1 to 2.0 mm.   The artificial turf structure according to claim 1 or 2, wherein the water absorbent resin is present in a surface layer portion of the filler. The artificial turf structure according to any one of claims 1 to 3, wherein a height of protrusion of the pile from the surface of the filler to the tip of the pile is 10 mm or more. A method for cooling an artificial turf structure in which a filler is filled between piles of artificial turf having a pile length of 30 mm or more ,
In order to satisfy the water holding power per unit area defined by the following formula of 50 to 2000 [g / m ² ] , the pure water absorption ratio is 3 to 150 [ g / g], the content per unit area is 0.5 to 100 [g / m ² ], and the artificial turf structure includes the filler in the artificial turf structure. A method for cooling an artificial turf structure, characterized in that the artificial turf structure is sprayed on a surface layer of a filler.
However, the water retention capacity per unit area is defined by the following formula.
(Water retention capacity per unit area) = (pure water absorption ratio) x (content per unit area)

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