Turf filler and turf using the same

Abstract

To provide a turf filler which is excellent in shock absorbing properties, can more surely suppress the rise of the surface temperature of turf, and does not pollute the environment even when flowing out to the environment outside the system, and to provide turf using the turf filler.SOLUTION: A turf filler of the present invention comprises 0.1 pt.wt. or more and less than 10 pts.wt. of paraffin wax per 100 pts.wt. of a base material composed of plant fibers, 10 pts.wt. or more and less than 100 pts.wt. of an inorganic filler, and 1 pt.wt. or more and 30 pts.wt. or less of a paste material, and is composed of granules having a particle size of 0.5 mm or more and 5 mm or less. The turf is characterized in that the gaps of the turf will be filled with the filler.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a lawn infill material that is used to fill gaps in grass in lawns made of natural or artificial grass. [Background technology]

[0002] A conventional filler of this type is described in the following Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-014268). This conventional technology is configured as follows. It is composed of granules made of a thermoplastic elastomer composition containing 100 parts by weight of thermoplastic elastomer and 10 to 100 parts by weight of bamboo powder with a particle size of 100 μm or less.

[0003] According to the above-mentioned prior art, it is possible to improve the weather resistance of the organic bamboo powder by dispersing bamboo powder of a specific size in a thermoplastic elastomer. As a result, it is possible to maintain the excellent temperature-reducing, antibacterial, and deodorizing effects of the bamboo powder over a long period of time, along with the shock absorption properties of the thermoplastic elastomer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-014268 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional techniques have the following problems. Bamboo powder is prone to blackening due to carbonization caused by heat when melted into thermoplastic elastomer, and granular materials containing blackened bamboo powder are prone to absorbing sunlight, which can lead to temperature increases. Furthermore, thermoplastic elastomers are composed of petroleum-derived plastics such as polyolefins, styrene polymers, polyurethanes, and polyamides, and are therefore not biodegradable. If filler material is blown away by wind or other factors and flows into the ocean via rivers or other sources, microplastics will be generated from the crushed filler, raising concerns about marine pollution caused by these microplastics.

[0006] Therefore, the main objective of the present invention is to provide a lawn infill that has excellent shock absorption properties, can more reliably suppress an increase in the surface temperature of the lawn, and will not pollute the environment even if it leaks into an external environment, as well as a lawn that uses this lawn infill. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a lawn infill (hereinafter simply referred to as "infill") configured as follows. That is, the composition is characterized by containing 0.1 parts by weight or more and less than 10 parts by weight of paraffin wax, 10 parts by weight or more and less than 100 parts by weight of inorganic filler, and 1 part by weight or more and 30 parts by weight or less of adhesive material relative to 100 parts by weight of a base material made of plant fiber, and being made of granular material with a particle size of 0.5 mm or more and 5 mm or less.

[0008] In this invention, the base material is made of plant fibers, which provide cushioning and shock absorption, reducing the strain on players' feet and knees caused by the hardening of artificial or natural turf used in sports fields and stadiums. Furthermore, the base material contains at least 0.1 parts by weight but less than 10 parts by weight of paraffin wax per 100 parts by weight of the base material. This paraffin wax forms a water-repellent coating on the filler's surface, allowing the filler to control the amount of moisture absorbed and released in response to temperature changes. As a result, when the filler reaches high temperatures, the paraffin wax melts and softens, reducing its water repellency. This increases the amount of moisture evaporating from the filler, thereby removing the heat of vaporization and enabling the filler to maintain its temperature rise suppression effect for a long period of time. Furthermore, by adding at least 10 parts by weight but less than 100 parts by weight of inorganic filler per 100 parts by weight of the base material and forming the filler into granular particles with a particle size of at least 0.5 mm and less than 5 mm, the apparent specific gravity of the filler can be increased. As a result, the filler is less likely to scatter during and after application, and it can also be prevented from adhering to the player's feet. In addition, the gaps between the dietary fiber, which is the base material of the filler, are larger, which improves elasticity, impact resistance, and resilience.

[0009] In the present invention, the melting point of the paraffin wax is preferably 60°C or higher. In this case, the effect of the filler in suppressing temperature rise is the most effective measure against heatstroke for players and other lawn users.

[0010] In the present invention, the adhesive material is preferably at least one selected from the group consisting of pregelatinized starch, modified starch, CMC, methyl cellulose, and PVA. In this case, the filler does not contain any components that could become microplastics or harmful components, and the filler is highly biodegradable, so even if it flows into the ocean, it can prevent environmental pollution such as microplastic contamination.

[0011] A second aspect of the present invention is a lawn in which any of the lawn infill materials described above is filled into gaps in the lawn. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a lawn infill that has excellent shock absorption properties and can more reliably suppress an increase in the surface temperature of the lawn, and that will not pollute the environment even if it leaks into an external environment, as well as a lawn that uses this lawn infill. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram showing the state of the grass in each example and comparative example of the present invention. [Figure 2] 1 is a graph showing the results of an impact absorption test in each of the examples and comparative examples. [Figure 3] 1 is a graph showing the results of a test of the temperature rise suppression effect in each example and comparative example. [Figure 4] 1 is a graph showing the results of biodegradability tests in each example and comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to specific examples. The lawn filler of the present invention contains 100 parts by weight of a base material made of plant fiber, 0.1 parts by weight or more but less than 10 parts by weight of paraffin wax, 10 parts by weight or more but less than 100 parts by weight of an inorganic filler, and 1 part by weight or more but less than 30 parts by weight of a glue material, and is composed of granular materials with a particle size of 0.5 mm or more but less than 5 mm.

[0015] The plant fiber used as the base material for the filler can be any type of plant, as long as it is powdered or pulverized. Specific examples include wood flour such as sawdust, coconut shells, bamboo powder, and rice husks. Among these, sawdust from cypress, cedar, and pine, which is generated at sawmills, contains plant essential oils. Using this sawdust as the base material is preferable because it gives off a woody scent, evoking the feeling of forest bathing. From the perspective of efficient resource utilization, used tea leaves, coffee grounds, and soybean pulp can also be used. Furthermore, processed dietary fibers such as paper powder and wood pulp can also be used.

[0016] Paraffin wax is a type of hydrocarbon compound, consisting of alkane C with 20 or more carbon atoms. n H 2n+2 It is primarily used as a raw material for candles and crayons. Paraffin waxes come in a variety of melting points, but to maximize water-repellent properties (and the temperature rise suppression function that utilizes this property) for fillers at room temperature, paraffin waxes with a melting point of 60°C or higher are preferred. If the paraffin wax melting point is below 60°C, the paraffin wax crystalline coating on the surface of the filler is likely to soften due to the influence of the outside temperature, resulting in a low water-repellent effect and, as a result, a low temperature rise suppression effect. In contrast, paraffin waxes with a melting point of 60°C or higher have paraffin crystals that soften when the artificial turf reaches temperatures above 60°C, allowing the moisture inside the filler to effectively dissipate.

[0017] The blending ratio of paraffin wax in the filler is preferably 0.1 part by weight or more and less than 10 parts by weight, and more preferably 1 part by weight or more and 5 parts by weight or less, per 100 parts by weight of the base material. If the blending ratio of paraffin wax is less than 0.1 part by weight per 100 parts by weight of the base material, a sufficient water-repellent effect for suppressing temperature rise in the filler cannot be obtained, and conversely, if it is 10 parts by weight or more, the water-repellent effect becomes too strong, reducing the water absorption of the filler, and in this case too, a sufficient temperature-rise suppression effect cannot be obtained.

[0018] The inorganic filler is used to give the molded filler a sense of weight, and any type of inorganic filler with a large apparent specific gravity can be used, such as calcium carbonate, zeolite, silicon dioxide, talc, titanium oxide, etc. Of these, calcium carbonate is preferred from the standpoint of availability and economy.

[0019] The blending ratio of the inorganic filler in the filler is preferably 10 parts by weight or more and less than 100 parts by weight, more preferably 20 parts by weight or more and 50 parts by weight or less, relative to 100 parts by weight of the base material. If the blending ratio of the inorganic filler is less than 10 parts by weight relative to 100 parts by weight of the base material, a sufficient apparent specific gravity cannot be imparted to the filler, whereas if it is 100 parts by weight or more, the apparent specific gravity of the filler becomes too large, resulting in a significant decrease in the impact absorption properties of the filler.

[0020] A paste is a material used as an excipient when forming a filler. While any type of paste can be used, it is preferable to use at least one selected from the group consisting of pregelatinized starch, modified starch, CMC, methylcellulose, and PVA. The pastes exemplified here are biodegradable and do not contain components that could become microplastics or that are harmful to humans or the environment. Among these, the raw materials for pregelatinized starch include tapioca, wheat, corn, and potato, with tapioca being particularly preferred due to its high adhesiveness.

[0021] The blending ratio of glue in the filler is preferably 1 part by weight or more and 30 parts by weight or less, and more preferably 5 parts by weight or more and 20 parts by weight or less, per 100 parts by weight of the base material. If the blending ratio of glue is less than 1 part by weight per 100 parts by weight of the base material, the dry strength will be low and the filler will break down into fine particles, while if it exceeds 30 parts by weight, the dry strength will be sufficient, but not only will it be uneconomical, but the burden on the machine when molding the filler will be too great, which may cause molding defects.

[0022] The filler of the present invention may be blended with an antibacterial material as needed. The antibacterial material is a material blended to protect the filler from decay caused by mold and bacteria. Examples of such antibacterial materials include thiapentazole, sodium benzoate, sorbic acid, potassium sorbate, didecylmethylammonium, benzalkonium chloride, polyphenols, silver, and copper. Taking into account the effect of addition and economic efficiency, the blending ratio of the antibacterial material in the filler is preferably 0.1 wt% or less of the total weight of the filler.

[0023] In addition to this antibacterial material, part of the base material may be replaced with charcoal or activated charcoal to improve water retention, or dyes or pigments may be added to improve aesthetic appeal.

[0024] When manufacturing a filler made from the above-mentioned raw materials, it is preferable to form the above-mentioned raw materials into pellets (granules) using a known molding machine such as a single-screw kneading extruder, a twin-screw kneading extruder, a disk pelletizer, or a ring die molding machine. Furthermore, the particle size of the filler formed into pellets is preferably 0.5 mm or more and 5 mm or less, more preferably 1 mm or more and 4 mm or less, from the viewpoints of ease of filling gaps in the turf and ease of movement for players. If the particle size of the filler is less than 0.5 mm, the filler will easily solidify and will not be able to exhibit sufficient shock absorption. Conversely, if the particle size exceeds 5 mm, sufficient shock absorption will be ensured, but it will be difficult to fill gaps in the turf and players and other users of the turf will feel a rough, uncomfortable feeling underfoot. [Example]

[0025] EXAMPLES The present invention will be explained in more detail below with reference to examples (and comparative examples), but the present invention is not limited to these examples.

[0026] Preparation of Example Samples Cypress sawdust was used as the base material, FP300 from Calfine Corporation as calcium carbonate, Moldex αk from Takara Starch Chemical Co., Ltd. as the adhesive, and SP0145 (melting point 62°C) from Nippon Seiro Co., Ltd. as paraffin wax. The mixture was adjusted to the blending ratios shown in Examples 1 to 4 in Table 1 below, and mixed in a mixer (manufactured by Dalton Corporation) while adding water to obtain a mixed raw material until the moisture content reached 20 to 30%. The mixed raw material was then placed in a molding machine (Disc Pelleter F20, manufactured by Dalton Corporation) and granulated to a width of 4 mm. The granulated mixed raw material was then dried at 150°C for 0.5 hours in a dryer (manufactured by Kawasaki Kiko Co., Ltd.) until the moisture content reached 20 wt% or less. Fine powder with a particle size of 1 mm or less was then removed by sieving, yielding fillers of Examples 1 to 4 with particle sizes uniformed between 1 and 4 mm. The filler of Example 5 was obtained in the same manner as in Examples 1 to 4 above, except that coconut shell powder was prepared (used) as the base material.

[0027] Preparation of comparative sample The fillers of Comparative Examples 1 and 2 shown in Table 1 below were prepared in the same manner as in the above-mentioned Examples. For the filler of Comparative Example 3, bamboo powder was used as the base material, FP300 from Calfine Corporation as calcium carbonate, and Esprene (registered trademark) 505A from Sumitomo Chemical Co., Ltd. as the synthetic rubber EPDM. These components were mixed in a mixer (manufactured by Dalton Corporation) according to the blending ratio shown in Comparative Example 3 in Table 1 below, and then extruded into strands at temperatures of 150°C to 180°C using a twin-screw kneading extruder (manufactured by Moriyama Corporation). The extruded product was then water-cooled and the particle size was adjusted to 1 to 4 mm to obtain the filler of Comparative Example 3. Furthermore, the filler of Comparative Example 5 in Table 1 below was obtained in the same manner as in Comparative Example 3, except that rice husk powder was used as the base material. Furthermore, for the filler of Comparative Example 4 in Table 1 below, coconut shell powder, silica sand (Shinozawa Silica Sand Industry Co., Ltd. No. 4), and EPDM rubber chips (particle size 1 mm to 3 mm) were prepared, and these raw materials were laid directly on a grass sheet substrate 10 (see Figure 1) to form the filler (details will be described later).

[0028] [Table 1]

[0029] The suitability of each filler of the following Examples and Comparative Examples as a lawn filler was evaluated by an impact absorption test, a temperature rise suppression test, and a biodegradability test.

[0030] Impact absorption test As shown in Figure 1, a 1m x 1m artificial turf was prepared by planting multiple piles 12 on a sheet substrate 10. For all Examples and Comparative Examples except Comparative Example 4, as shown on the left side of Figure 1, silica sand (Shinozawa Silica Sand Industry Co., Ltd. No. 4) was laid on the sheet substrate 10 to form a 2cm-thick silica sand layer, and then each filler material was laid on top of the silica sand layer to form a 2cm-thick infill layer to prepare the turf sample. Meanwhile, for Comparative Example 4, as shown on the right side of Figure 1, rice husk powder and silica sand were laid on the sheet substrate 10 of the above-mentioned artificial turf to form a 3cm-thick infill layer, and then EPDM rubber chips were laid on top of the infill layer to form a 1cm-thick elastic granular layer to prepare the turf sample.

[0031] The turf samples (immediately after construction) of each of the examples and comparative examples constructed as described above were compacted by vibrating them using a compactor (plate compactor HVP80W manufactured by Meiwa Seisakusho Co., Ltd., total weight 100 kg, vibration dimensions 480 mm x 500 mm) for the elapsed times (30 minutes and 1 hour) shown in Table 2 below. Then, using a simple bearing capacity measuring device called "Caspol," a rammer (weight) with a diameter of 50 mm and a mass of 4.5 kg was allowed to freely drop from a height of 45 cm. The impact acceleration measured by the accelerometer built into the rammer was used to calculate the impact value (Ia value) using Equation 1 below. This test was repeated five times to determine the average of the impact values (Ia average value), and the Ia value increase rate was calculated using Equation 2 below. These values were used as indicators of impact absorption. Impact value (Ia value) = acceleration (gal) / 2.78 x 980 (gal) ... (Equation 1) Ia value increase rate (%) = average Ia value after time has elapsed / average Ia value immediately after construction × 100 ... (Formula 2) The simple bearing capacity measuring device "Caspol" is a measuring device developed by the Kinki Technical Office of the Kinki Regional Construction Bureau of the Ministry of Construction (currently the Kinki Regional Development Bureau of the Ministry of Land, Infrastructure, Transport and Tourism), and is a device that measures the condition of the ground based on the basic principle of the impact acceleration method. The results are shown in Table 2, and the change in Ia value over time is shown in FIG.

[0032] [Table 2]

[0033] As shown in Table 2 above, in Examples 1-5 and Comparative Examples 1 and 2, when compacted with a roller for 30 minutes, an increase of up to 11.3% from the initial hardness was observed, and when compacted for 1 hour, an increase of up to 12.5% from the initial hardness was observed. In contrast, in Comparative Examples 3-5, when compacted with a roller for 30 minutes, an increase of at least 12.4% from the initial hardness was observed, and when compacted for 1 hour, an increase of at least 26.7% from the initial hardness was observed. Furthermore, as shown in Figure 2, in Examples 1-5 and Comparative Examples 1 and 2, the increase in the average Ia value over time after compaction with a roller was gradual, whereas in Comparative Examples 3-5, the average Ia value tended to increase rapidly over time after compaction with a roller. These results suggest that Examples 1-5 and Comparative Examples 1 and 2 have higher shock absorption properties than Comparative Examples 3-5, even when subjected to long-term vibration and compaction.

[0034] Temperature rise suppression test As shown in Figure 1, a 0.5m x 0.5m artificial turf was prepared by planting multiple piles 12 on a sheet substrate 10. For all Examples and Comparative Examples except Comparative Example 4, as shown on the left side of Figure 1, silica sand was laid on the sheet substrate 10 to form a 2cm thick silica sand layer, and then each filler material was laid on top of the silica sand layer to form a 2cm thick infill layer to prepare the turf sample. Meanwhile, for Comparative Example 4, as shown on the right side of Figure 1, rice husk powder and silica sand were laid on the sheet substrate 10 of the above-mentioned artificial turf to form a 3cm thick infill layer, and then EPDM rubber chips were laid on top of the infill layer to form a 1cm thick elastic granular layer to prepare the turf sample.

[0035] For each of the turf samples constructed as described above, a K-type thermocouple (E52, manufactured by Omron Corporation) was installed as a thermometer at a height of 4 cm from the surface of the packed bed or elastic granular layer. The K-type thermocouple was positioned so that it was not directly exposed to the light of the heat source described below. A floodlight (200W, manufactured by Hataya Limited) was used as the heat source, and light was irradiated from a height of 1 m above the surface of the packed bed or elastic granular layer. The temperature change of the K-type thermocouple was measured with a recorder. Since heatstroke is generally a risk for humans when the surface temperature of artificial turf reaches 60°C (time 0), 1 liter of water was sprinkled over the entire turf sample when the surface temperature of the turf sample reached 60°C. The temperature was measured and recorded every hour for up to 3 hours after watering. After 3 hours, turf sample surface temperatures below 60°C were evaluated as having a temperature rise suppression effect (◯), and those above 60°C were evaluated as not having a temperature rise suppression effect (×). The results obtained are shown in Table 3 and FIG.

[0036] [Table 3]

[0037] 3 above, in Examples 1 to 5, the surface temperature of the lawn sample was below 60°C three hours after watering, whereas in Comparative Examples 1 to 5, the surface temperature of the lawn sample was above 60°C three hours after watering. Thus, the results showed that Examples 1 to 5 were effective in suppressing a rise in lawn temperature, whereas Comparative Examples 1 to 5 were not.

[0038] Biodegradability test (BOD method) The biodegradability test (BOD method) measures the percentage (%) of organic matter in a filler that is decomposed by microorganisms over a certain period of time, and this percentage serves as an indicator of how easily it decomposes in the environment. Specifically, the test was conducted in accordance with the measurement method of the Japan Food Research Laboratories (JFRC) as follows: 30 g of filler was used as a test sample and cultured in a sealed container, and the amount of enzyme consumed by microbial decomposition, i.e., BOD (biochemical oxygen demand), was continuously measured. The measured amount of oxygen (BOD) and the amount of oxygen required for the sample to be completely decomposed and become inorganic, ThOD (theoretical oxygen demand), were applied to the following formula 3 to calculate the degree of biodegradation (%). Biodegradation rate (%)=BOD / ThOD×100…(Equation 3) The results are shown in Table 4 and Figure 4. The "pass level" in Table 4 and Figure 4 is an index for determining "ready biodegradability," and if the biodegradability reaches the pass level within 28 days, the substance is determined to decompose quickly in the environment, i.e., to be readily biodegradable.

[0039] [Table 4]

[0040] From Table 4 and Figure 4 above, it can be seen that in Examples 1 to 5 and Comparative Example 2, the biodegradability reached the pass level 21 days after the start of the test, whereas in Comparative Examples 3 to 5, the biodegradability did not reach the pass level 28 days after the start of the test, indicating low biodegradability. [Industrial Applicability]

[0041] The lawn filler of the present invention can also be suitably used as a ground mix by mixing it with the soil of a ground where no lawn is laid. [Explanation of symbols]

[0042] 10: Sheet substrate, 12: Pile.

Claims

1. For 100 parts by weight of a base material made of plant fibers, Paraffin wax in an amount of 0.1 parts by weight or more and less than 10 parts by weight, an inorganic filler in an amount of 10 parts by weight or more and less than 100 parts by weight; and Contains 1 part by weight or more and 30 parts by weight or less of a glue material, A lawn filler characterized by being made of granular material having a particle size of 0.5 mm or more and 5 mm or less.

2. The lawn filler of claim 1, A lawn filler characterized in that the melting point of the paraffin wax is 60°C or higher.

3. The lawn filler of claim 1 or 2, The lawn filler is characterized in that the adhesive is at least one selected from the group consisting of pregelatinized starch, modified starch, CMC, methyl cellulose, and PVA.

4. A lawn in which the lawn filler according to claim 1 or 2 is filled into gaps in the lawn.

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