JPH0216404B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an athletic field made of artificial turf, and more particularly to an athletic field made of artificial turf, which is formed by filling the artificial turf with dry sand.

Generally, artificial lawns are made of flat pile threads made from synthetic resins such as polyamide, acrylic, vinylidene chloride, or polypropylene, which are grafted onto a backing fabric using various methods.
The pile length and turf density differ slightly depending on the stadium to which it is applied, such as a tennis court or soccer field, but the length is generally around 7 to 12 mm. Artificial lawns have become rapidly popular in recent years because they are more durable and easier to maintain than natural lawns, but there are still issues that need to be resolved in terms of their characteristics and construction. left behind.

According to previous examples, it has been reported that by filling the grains of an artificial lawn with dried sand (mineral particles), the characteristics of the artificial lawn can be made to more closely resemble those of a natural lawn. Although this dry sand satisfies the buffering capacity of the artificial lawn and the ability to prevent spikes from getting caught, the following points must be kept in mind. That is,
In order to increase the water retention capacity of this sand layer, the finer the particle size, the better. However, if the particle size is too small, it will harden over time, impairing the appropriate cushioning properties, and the sand filling process will be difficult. During construction, or after construction, the sand is blown up by the wind, which is unfavorable in terms of occupational safety and health and environmental health. This dust generation is particularly problematic in indoor courts. For this reason, in the past, soil fixatives were sprinkled on top of the filled sand layer to harden the surface, or the grain size of the sand was kept to a certain level, and moisture retaining materials such as vermiyquilite or calcium chloride were used instead. It may be mixed in.

However, the method using a soil fixative is not very permanent, is troublesome in terms of maintenance, and is not preferable in terms of cost. On the other hand, as for the moisture retaining material, mixing it into the sand layer requires a certain amount of effort, and like the former, cost problems remain.

Therefore, an object of the present invention is to provide a playing field surface that has characteristics similar to natural grass in terms of buffering capacity and ability to prevent spikes from getting caught, as well as water retention capacity, and which is easy to maintain after rain and is flat. To provide an athletic field made of artificial grass that is easy to construct and has a sand layer that generates extremely little dust due to wind or the like.

The above purpose is, first of all, to form a lower layer of fine dry sand below the grain of the artificial lawn;
This is achieved by filling and layering coarse dry sand on top. In this case, fine dry sand is 100
The coarse dry sand preferably contains 80% or more of grain size between 70 mesh and 28 mesh, and the coarse dry sand preferably contains 80% or more of grain size between 70 mesh and 14 mesh.

Further, according to the present invention, the ground below where the artificial lawn is laid is made of crushed stone, volcanic gravel, or/and sand and is made of water permeable material, and the upper surface thereof is made of synthetic fibers such as polypropylene, polyamide, polyester, etc. A bulky felt-like nonwoven fabric sheet formed by a spunbond method, a needle punch method, or the like is spread to form a substantially flat sheet.

In the permeable ground of the present invention formed in this way, the recesses formed between the individual crushed stones, etc. constituting the upper surface thereof are filled with the nonwoven fabric, and the ridges of each crushed stone, etc. The entanglement with the nonwoven fabric prevents each crushed stone from rolling, and as a result, it is constructed as a flat and firm ground.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

This athletic field consists of a ground 1 whose upper surface is finished substantially flat, an artificial lawn 2 laid on this ground 1, and dry sand 3 filled in the grass grains of this artificial lawn 2. We are prepared. In this example, the ground 1 consists of stabilized crushed stone, volcanic gravel, and/or sand. That is, a stabilizer such as cement or quicklime is mixed into the crushed stone, etc., and an appropriate amount of clay as a moisture donor is added as needed, and then it is spread evenly and the surface is compacted or not compacted. Level it out roughly evenly. However, in order to have sufficient support capacity for the load applied from above after completion, the ground 1 is usually composed of the above-mentioned crushed stone with a particle size of about 25 mm, so its upper surface is uneven and There are many gaps between crushed stones, making them unstable.

Therefore, in this example, a felt-like nonwoven fabric sheet 4 made of polypropylene is spread on the surface of the ground 1 to form a substantially flat surface.

By laying this non-woven fabric sheet 4, the upper surface of the ground 1, which has many gaps between crushed stones and lacks stability because crushed stones, etc. with a relatively large diameter and many surface irregularities are simply laid down, is flattened. Since the artificial turf is stabilized and stabilized, the artificial turf can be laid more evenly and stably.

The artificial lawn 2 consists of a backing base fabric 5 and pile threads 6 planted on the base fabric 5. In this case, the base fabric 5 is made of crushed stone, volcanic gravel, or/and sand that has been stabilized by the ground 1, and in order to prevent the stability from being weakened and weakened by rainwater penetration, the base fabric 5 is made of non-woven fabric. Made to be water permeable. This water impermeability can be obtained by, for example, backing the base fabric 5 with rubber or urethane resin.

The pile yarn 6 can be made of various synthetic resins, but in terms of appearance and texture it is more similar to natural grass, and considering durability, it is made of polyamide, polyethylene terephthalate, polyurethane, polyvinylidene chloride, polypropylene, or Acrylic resins are preferred, and are made from slit yarns obtained by cutting films of these resins, or from flat yarns formed by melt spinning through nozzles having irregular cross-sectional holes. Considering that this artificial grass 2 is used in place of conventional natural grass in tennis courts, soccer fields, baseball fields, etc., it is preferable that the pile length is 10 mm to 40 mm. In addition,
According to this invention, the dry sand 3 has two layers: a lower layer 7 made of fine dry sand filled on the base fabric 5, and an upper layer 8 made of coarse dry sand layered thereon.
Consists of layered structure. In this case, fine dry sand is defined as containing preferably more than 80% sand with a grain size of 100 mesh to 28 mesh (approximately 0.15 mm to approximately 0.6 mm), while coarse dry sand is defined as having a grain size of 70 mesh
mesh to 14 mesh (approx. 0.21 mm to approx.
1.2 mm), preferably 80% or more. When this dry sand 3 is spread on the artificial lawn 2, it is filled into the grass grains, but if the particle size is finer than 100 mesh, it tends to be gradually pounded and hardened by the pressure of the players. In addition, there is a risk that it may be blown up as dust, which is unfavorable from the standpoint of occupational safety and health as well as environmental health, especially in the case of indoor facilities. In view of this, in this invention, the particle size of the fine dry sand used in the lower layer is within the above-mentioned range, thereby reducing the friction speed of the wind to 15 cm/s (the wind speed on the ground is approximately 4 cm/s).
(corresponding to m), combined with the erosion control effect of the pile yarns 6, there is almost no blowing away, and therefore, especially during construction, the amount of dust generated is extremely small. Furthermore, considering the relationship with the particle size, we were able to obtain results that were satisfactory to some extent in both water retention capacity and drainage performance, and even without mixing water retention materials such as vermiyquilite or calcium chloride as in the past, we were able to achieve results that are almost comparable to those of conventional water retention materials. Water retention capacity is indicated. Also,
Since the coarse dry sand having the particle size range described above is layered on the lower layer of fine dry sand, there is almost no risk that the entire layer will be blown away by the influence of the wind.

On the other hand, the layer thickness of the dry sand 3 including the lower layer 7 and the upper layer 8 is about 70% to 110% of the length of the pile yarn 6.
is appropriate. Note that this value is based on the time of completion of construction, and in reality, the level decreases over time due to rainfall and tread pressure, and stabilizes after approximately one month.
Therefore, the layer thickness is selected in relation to, for example, the bouncing characteristics of the ball and the aesthetic appearance of the artificial lawn. That is, if enough sand is added to cover the tips of the pile yarns 6, the pile yarns 6 will stand upright, and
Since it becomes rigid, the bounce of the ball becomes higher and the durability is improved, but on the other hand, the green color of the artificial lawn 2 becomes less conspicuous and the aesthetics are slightly inferior.

On the other hand, if the amount of sand 3 is reduced and the tips of the pile threads 6 are made to protrude more from the upper surface of the sand layer, the playing surface becomes more flexible and the hound of the ball becomes lower. Moreover, although the green color of the artificial lawn 2 stands out and is aesthetically pleasing, on the contrary, the pile threads 6 wear out more quickly. Note that the ratio of the layer thicknesses of the lower layer 7 and the upper layer 8 is appropriately determined by taking into consideration water retention and the like.

As is clear from the above description of the embodiments, according to the present invention, the base is made of crushed stone, volcanic gravel, sand, etc. to have a water-permeable structure, and moreover, the grass grains of the artificial lawn are filled with a large amount of sand. This allows for good water drainage even when there is a relatively large amount of rainfall, and the effort required for maintenance during rainfall is significantly reduced.In addition, the ground is formed from easily available materials such as crushed stone, volcanic gravel, and sand, making it easier to use than conventional materials. When converting a clay court or antuca court into an all-weather court, it is cheaper and easier to construct than an asphalt-based court. Furthermore, the upper surface of the ground, which is made of a material with relatively sharp edges and many surface irregularities, such as crushed stone, is smoothed with a bulky non-woven fabric sheet before the artificial lawn is laid. This prevents the individual pieces of crushed stone from rolling and creates a flat, solid foundation. This means that an artificial grass athletic field that is stable in appearance and dimensions can be obtained.

Further, according to the present invention, between the turf grains or pile threads of the artificial lawn, there is a lower layer consisting of fine dry sand containing 80% or more of sand in the range of 100 mesh to 28 mesh, and a lower layer of fine dry sand in the range of 70 mesh to 14 mesh. By layering the artificial lawn with an upper layer of coarse dry sand that contains more than 80% of the sand in the grass, the scattering of sand is avoided when the sand is spread on the artificial lawn and filled into the grass grains. The amount is small and there is little risk of causing occupational safety and health problems. Further, since the fine dry sand in the lower layer is held down by the coarse dry sand in the upper layer, there is no need to spread a soil fixing agent on the sand layer to harden the surface as in the conventional method to prevent the sand from scattering. Furthermore, since it exhibits a good value for water retention capacity, there is no need to mix water retention materials such as permiyulite or calcium chloride. Therefore, it is easy to construct and is advantageous in terms of cost.

[Brief explanation of drawings]

The figure is a cross-sectional view showing a portion of an athletic field made of artificial grass according to the present invention. In the diagram, 1 is the ground, 2 is artificial grass, 3 is dry sand,
4 is a layer consisting of slag dust etc. and soil fixative;
5 is a backing base fabric, 6 is a pile yarn, 7 is a lower layer, and 8 is an upper layer.

Claims (1)

[Scope of Claims] 1. A permeable ground made of crushed stone and/or sand and having a substantially flat upper surface, an artificial lawn laid on the ground, a base fabric, and the base fabric. The artificial lawn is made of pile yarn having a length in the range of 10 mm to 40 mm, and the artificial lawn is filled with dry sand having a thickness of 70% to 110% of the pile length. The dry sand includes:
An athletic field made of artificial turf having a two-layer structure including a lower layer made of fine dry sand layered on the base fabric and an upper layer made of coarse dry sand layered on the lower layer, wherein the water permeable An athletic field made of artificial grass, characterized in that the upper surface of the ground is formed substantially flat by spreading a bulky non-woven sheet. 2 The lower layer of the two-layered dry sand filled in the artificial lawn contains 80% or more of fine dry sand with a particle size in the range of 100 mesh to 28 mesh, and the upper layer of the dry sand has a particle size of 100 mesh to 28 mesh. 70 meters or 14
The artificial grass sports field according to claim 1, which contains 80% or more of coarse dry sand within the mesh area.