Elastic chip, manufacturing method of the same, covering material and artificial turf containing filler

Abstract

To provide an elastic chip capable of not only suppressing temperature rise but also having high durability.SOLUTION: An elastic chip is formed from a rubber composition containing a rubber constituent and a bamboo powder, and the rubber constituent has a thermosetting elastomer as the main body. The elastic chip can suppress temperature rise even when being used for instance, in the outside due to containing the bamboo powder, and has excellent heat resistance due to that the rubber constituent has the thermosetting elastomer as the main body, and even if a temperature rises, rubber physical properties are hardly lowered. The elastic chip can be manufactured by an elastic chip manufacturing method which passes a blending step of blending a raw material rubber in an uncross-linked or semi-cross-linked state with the bamboo powder and a cross-linking agent so as to obtain a composition before cross-linking, and a cross-linking step of cross-linking the composition before cross-linking.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an elastic chip and a method for manufacturing the same. The present invention also relates to artificial turf filled with a filler containing the elastic chip and a coating material using the elastic chip.

Background Art

[0002] Granular elastic chips (rubber chips) made of an elastic material are used as filling materials for artificial turf, paving materials in parks, etc. As the elastic chips, waste tire chips obtained by crushing waste tires, colored waste tire chips obtained by coloring waste tire chips, etc. are often used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, waste tire-based elastic chips have a problem that the temperature easily rises due to sunlight, etc. In this regard, Patent Document 1 describes a granular material (elastic chip) for artificial turf composed of a thermoplastic elastomer composition containing a thermoplastic elastomer and bamboo powder having a particle size of 100 μm or less. According to the same document, by dispersing bamboo powder in the thermoplastic elastomer, it is possible to exhibit a temperature reduction effect over a long period.

[0005] However, in recent years when global warming has been a major concern, the artificial turf granules described in Citation 1 may not be able to withstand outdoor use. This is because thermoplastic elastomers tend to have a decrease in rubber physical properties with an increase in temperature. Therefore, the artificial turf granules in that document may not be able to exhibit sufficient elasticity when the temperature rises due to strong sunlight in summer or the like. Moreover, since artificial turf is often laid in places where it will be repeatedly stepped on, the artificial turf granules in that document may even have a risk of plastic deformation when repeatedly stepped on in a state where the temperature has risen. And in the artificial turf granules of that document, due to the mixing of bamboo powder, it is highly likely that the rubber physical properties are more likely to decrease compared to the case of thermoplastic elastomer alone, so the above problems are considered to be more prominent.

[0006] The present invention has been made to solve the above problems, and provides an elastic chip that can not only suppress the rise in temperature but also has high durability. Another object of the present invention is to provide a method for manufacturing this elastic chip. Furthermore, it is also an object of the present invention to provide artificial turf filled with this elastic chip and a coating material using this elastic chip.

Means for Solving the Problems

[0007] The above problems are solved by providing an elastic chip formed of a rubber composition containing a rubber component and bamboo powder, wherein the rubber component is mainly a thermosetting elastomer. elastic chip by doing so.

[0008] This elastic chip obtains a pre-crosslinking composition by mixing an uncrosslinked or semi-crosslinked raw rubber, bamboo powder, and a crosslinking agent, and a crosslinking step of crosslinking the pre-crosslinking composition The manufacturing method of the elastic chip passing through can be manufactured by.

[0009] Here, "the rubber component is mainly composed of a thermosetting elastomer" means that the proportion of the thermosetting elastomer in the rubber component is 70% by weight or more. The proportion of the thermosetting elastomer in the rubber component is preferably 80% by weight or more, more preferably 90% by weight or more, and even more preferably 99% by weight or more.

[0010] In the elastic chip according to the present invention, by containing bamboo powder, as shown in the later experimental examples, the temperature rise can be suppressed. Also, deodorizing and bactericidal effects by bamboo powder are expected. Furthermore, in recent years, bamboo damage has often become a problem. By using bamboo powder, the surplus bamboo can be effectively utilized, so the environmental load can be reduced compared to general heat-insulating elastic chips using heat-insulating pigments and the like.

[0011] In addition, in the elastic chip according to the present invention, as the rubber component, one mainly composed of a thermosetting elastomer with high heat resistance is used. Thereby, even if the temperature rises, the rubber physical properties of the elastic chip (rubber composition) can be made less likely to deteriorate. Also, the elastic chip according to the present invention can be manufactured by crosslinking in the crosslinking step after mixing bamboo powder into the raw rubber in the mixing step, so the bamboo powder can be firmly held in the rubber crosslinking network. Therefore, the decrease in rubber physical properties due to the addition of bamboo powder can be significantly suppressed, and the bamboo powder can be made less likely to fall off. For this reason, the elastic chip according to the present invention can exhibit high durability even in long-term use in an environment where strong sunlight continues for a long time.

[0012] In the elastic chip according to the present invention, it is preferable to further contain one or more coupling agents selected from the group consisting of silane coupling agents, aluminate coupling agents, and titanate coupling agents. Thereby, as shown in the following experimental examples, the rubber physical properties of the elastic chip (rubber composition) can be further enhanced. As the coupling agent, it is particularly preferable to use one having a mercapto group. Thereby, the rubber physical properties of the elastic chip can be further enhanced.

[0013] In the elastic chip according to the present invention, it is preferable to further contain white carbon. Thereby, the strength of the elastic chip can be enhanced.

[0014] The elastic chip according to the present invention can be used, for example, for artificial turf with a filler filled between the piles of the artificial turf pile. The elastic chip according to the present invention can alternatively be used as a covering material for the ground or a structure.

Effects of the Invention

[0015] As described above, according to the present invention, it is possible to provide an elastic chip that can not only suppress a temperature rise but also has high durability. It is also possible to provide a method for manufacturing this elastic chip. Furthermore, it is also possible to provide artificial turf with a filler filled with this elastic chip and a covering material using this elastic chip.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0017] 1. Overview A preferred embodiment of the present invention will be described more specifically. The elastic chip of this embodiment is granular and is formed of a rubber composition containing a rubber component and bamboo powder. The bamboo powder is contained in the elastic chip in a state of being dispersed in the rubber component. This elastic chip can be used for outdoor applications, for example, as a filling material for artificial turf, a covering material for the ground or a structure, etc. Conventional general rubber chips (for example, those obtained by coloring waste tire chips) tend to have an increased temperature of the rubber chip and a high surface temperature when used outdoors due to sunlight or the like. In contrast, the elastic chip of this embodiment contains bamboo powder and thus is less likely to have its temperature increased, as shown in later experimental examples. Thereby, it can be suitably used even in places where suppression of temperature rise is desired.

[0018] 2. Composition The elastic chip of this embodiment is formed of a rubber composition containing a rubber component, bamboo powder, a coupling agent, and white carbon.

[0019] 2.1 Rubber Component The rubber component in the elastic chip of this embodiment is mainly a thermosetting elastomer. The thermosetting elastomer is excellent in heat resistance compared to, for example, thermoplastic elastomers. Therefore, in the elastic chip of this embodiment, even if the temperature rises, the rubber physical properties are less likely to deteriorate and it is easy to maintain excellent elasticity. Also, even if it is repeatedly stepped on in a state where the temperature has risen, it is less likely to undergo plastic deformation and is excellent in durability.

[0020] The thermosetting elastomer is obtained by crosslinking a raw rubber (thermosetting elastomer before crosslinking) with a crosslinking agent. The specific type of the raw rubber is not particularly limited as long as it can be crosslinked by the crosslinking agent. Examples of the raw rubber include ethylene propylene diene rubber (EPDM), ethylene propylene rubber (EPM), styrene butadiene rubber (SBR), butadiene rubber (BR), butyl rubber (IIR), natural rubber (NR), acrylonitrile butadiene rubber (NBR), isoprene rubber (IR), chloroprene rubber (CR), acrylic rubber (ACM), silicone rubber, fluorine rubber, urethane rubber, etc. Among them, it is preferable to use raw rubbers capable of being crosslinked (vulcanized) with sulfur, such as EPDM, EPM, SBR, BR, IIR, NR, NBR, IR, etc. The raw rubber contained in the elastic chip may be only one type or two or more types. In the present embodiment, EPDM is adopted as the raw rubber. EPDM has excellent weather resistance and is characterized in that the rubber physical properties are less likely to deteriorate even when a large amount of filler or the like is added.

[0021] The crosslinking agent varies depending on the type of the raw rubber, and the type thereof is not limited. As the crosslinking agent, sulfur (elemental sulfur), sulfur compounds (inorganic sulfur compounds, organic sulfur compounds), organic peroxides, etc. can be used. In the present embodiment, elemental sulfur is used as the crosslinking agent.

[0022] The ratio of the crosslinking agent to the raw rubber also varies depending on the type of the raw rubber and is not particularly limited. The content of the crosslinking agent is preferably 0.5 parts by weight or more, preferably 1 part by weight or more, and more preferably 1.5 parts by weight or more with respect to 100 parts by weight of the raw rubber. Also, the content of the crosslinking agent is preferably 10 parts by weight or less, more preferably 5 parts by weight or less, and more preferably 3 parts by weight or less with respect to 100 parts by weight of the raw rubber.

[0023] The rubber component may include a thermoplastic elastomer in addition to the thermosetting elastomer. However, if the content of the thermoplastic elastomer is too high, it may be difficult to enhance the heat resistance of the elastic chip. For this reason, among the rubber components, the proportion of the thermoplastic elastomer usually accounts for 30% by weight or less, preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 1% by weight or less. In the present embodiment, substantially all of the rubber component is composed of the thermosetting elastomer, and the content of the thermoplastic elastomer is substantially 0% by weight. Examples of the thermoplastic elastomer include styrene-based elastomers, olefin-based elastomers, vinyl chloride-based elastomers, chlorinated polyethylene-based elastomers, chlorosulfonated ethylene-based elastomers, urethane-based elastomers, polyester-based elastomers, polyamide-based elastomers, silicone-based elastomers, acrylic-based elastomers, fluorine-based elastomers, and the like.

[0024] 2.2 Bamboo powder As the bamboo powder, the sieved product of crushed bamboo (bamboo powder product) is used. It is preferable to dry the bamboo before or after sieving. This can prevent the bamboo powder from fermenting or rotting. The moisture content of the bamboo powder (the moisture content measured using an electric resistance type moisture meter. The same shall apply hereinafter) is preferably 20% or less, and more preferably 15% or less. However, if the moisture content of the bamboo powder is too low, the temperature rise suppression function obtained by the bamboo powder may be limited. For this reason, the moisture content of the bamboo powder is preferably 1% or more, more preferably 5% or more, and even more preferably 8% or more.

[0025] The size of the bamboo powder is not limited, but if it is too large, it may be difficult to disperse the bamboo powder in the rubber component. Therefore, the size of the bamboo powder is usually 500 μm or less. The size of the bamboo powder is preferably 300 μm or less, and more preferably 200 μm or less. That is, the mesh opening of the sieve for screening the bamboo powder is usually 500 μm or less, preferably 300 μm or less, and more preferably 200 μm or less. The lower limit of the size of the bamboo powder is not limited, but it is usually 5 nm or more. In this embodiment, the bamboo powder having a size of approximately 150 μm or less and a moisture content of 10% or less is used by passing the pulverized bamboo powder through a 100-mesh (mesh opening approximately 150 μm) sieve after drying.

[0026] The addition amount of the bamboo powder in the rubber composition is not limited, but if it is too small, it may be difficult to suppress the temperature rise of the elastic chip. Therefore, the addition amount of the bamboo powder is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and even more preferably 15 parts by weight or more with respect to 100 parts by weight of the raw rubber. However, if the addition amount of the bamboo powder is too large, it may be difficult to improve the rubber physical properties of the elastic chip (rubber composition). Therefore, the addition amount of the bamboo powder is preferably 40 parts by weight or less, more preferably 30 parts by weight or less, and even more preferably 25 parts by weight or less with respect to 100 parts by weight of the raw rubber.

[0027] 2.3 Coupling Agent In the elastic chip of the present embodiment, by containing a coupling agent, as shown in the subsequent experimental examples, the rubber physical properties of the elastic chip (rubber composition) can be further enhanced. This is because the coupling agent can firmly bond the raw rubber and bamboo powder, and can further suppress the decrease in rubber physical properties due to the addition of bamboo powder. In addition, the raw rubber and white carbon can also be bonded, and thereby the rubber physical properties of the elastic chip (rubber composition) can be further enhanced. As the coupling agent, for example, a silane-based coupling agent, an aluminate-based coupling agent, a titanate-based coupling agent, etc. can be used. The coupling agent contained in the elastic chip may be only one of these, or two or more. In the present embodiment, among these, a silane-based coupling agent is adopted.

[0028] The coupling agent usually has an inorganic reactive group and an organic reactive group in the molecule. Examples of the inorganic reactive group include an alkoxy group. The alkoxy group can form a covalent bond with the hydroxyl group on the surface of bamboo powder through a dehydration condensation reaction. The alkoxy group preferably has 1 to 5 carbon atoms, and more preferably 1 to 2 carbon atoms (methoxy group or ethoxy group). The number of inorganic reactive groups contained in one molecule of the coupling agent is usually 1 to 3, and preferably 2 to 3. In the present embodiment, a coupling agent containing 3 inorganic reactive groups in one molecule is used.

[0029] The type of the organic reactive group is not particularly limited as long as it can bind to the raw rubber to be used. Examples of the organic reactive group of the coupling agent include a mercapto group (including a mercapto group protected by a protecting group exemplified by a silyl group, etc.; the same shall apply hereinafter), an acrylic group, a methacrylic group, a vinyl group, an amino group, an epoxy group, an isocyanate group, an isocyanurate group, etc. Among them, it is preferable to adopt a mercapto group, an acrylic group or a methacrylic group. The number of organic reactive groups contained in one molecule of the coupling agent is not particularly limited, but is preferably 1 to 4, and more preferably 1 to 2. When a plurality of organic reactive groups are contained in one molecule of the coupling agent, these organic reactive groups may be of the same type or different types. In the present embodiment, a coupling agent containing only one organic reactive group in one molecule is used.

[0030] Examples of the coupling agent include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, etc. The coupling agent contained in the elastic chip may be only one kind or two or more kinds. In the present embodiment, 3-mercaptopropyltrimethoxysilane containing three methoxy groups and one mercapto group in one molecule is adopted as the coupling agent.

[0031] The addition amount of the coupling agent varies depending on the type of the coupling agent and the like and is not limited. However, if the addition amount of the coupling agent is too small, it may be difficult to enhance the rubber physical properties of the elastic chip. Therefore, the addition amount of the coupling agent is preferably 0.1 part by weight or more, more preferably 0.3 part by weight or more, and further preferably 0.5 part by weight or more with respect to 100 parts by weight of the raw rubber. Also, the addition amount of the coupling agent is preferably 0.5 part by weight or more, more preferably 1 part by weight or more, and further preferably 2 part by weight or more with respect to 100 parts by weight of the bamboo powder.

[0032] On the other hand, if the addition amount of the coupling agent is too large, it may be difficult to improve the rubber physical properties of the elastic chip, or the cost of the elastic chip may become too high. Therefore, the addition amount of the coupling agent is preferably 2 parts by weight or less, more preferably 1 part by weight or less, and even more preferably 0.8 part by weight or less based on 100 parts by weight of the raw rubber. Further, the addition amount of the coupling agent is preferably 6 parts by weight or less, more preferably 5 parts by weight or less, and even more preferably 4 parts by weight or less based on 100 parts by weight of the bamboo powder.

[0033] 2.4 White Carbon The elastic chip of the present embodiment contains white carbon (a reinforcing filler mainly composed of silicic acid or a silicic acid compound or a mixture thereof). Thereby, the strength of the elastic chip can be increased. White carbon is less likely to reduce the temperature rise suppressing function of the elastic chip compared to, for example, carbon black. Further, in the elastic chip of the present embodiment containing a coupling agent, by adopting white carbon as a filler, the coupling agent can bond white carbon and the raw rubber, and it is possible to prevent the rubber physical properties of the elastic chip from easily decreasing. As the white carbon, wet silica or / and dry silica can be used. In the present embodiment, wet silica is used.

[0034] The addition amount of white carbon is not limited, but if it is too small, it may be difficult to increase the strength of the elastic chip. Therefore, the addition amount of white carbon is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, and even more preferably 15 parts by weight or more based on 100 parts by weight of the raw rubber. On the other hand, if the addition amount of white carbon is too large, the elastic chip may become too hard and may lose the desired elasticity. Therefore, the addition amount of white carbon is preferably 30 parts by weight or less, more preferably 25 parts by weight or less, and even more preferably 20 parts by weight or less based on 100 parts by weight of the raw rubber.

[0035] 2.5 Others In addition to the above-described components, the elastic chip may contain, for example, fillers other than white carbon, processing aids, plasticizers (softening agents), zinc white (or / and activated zinc white), crosslinking accelerators (vulcanization accelerators), crosslinking regulators (for example, glycols such as polyethylene glycol having a number average molecular weight of 200 or more and 20000 or less, amines, etc.), thickeners (for example, tackifiers, etc.), anti-aging agents, coloring materials (for example, heat-shielding pigments, etc.).

[0036] As fillers other than white carbon, for example, calcium carbonate, talc, clay, etc. can be used. The fillers contained in the elastic chip may be only one type or two or more types. The addition amount of all fillers including white carbon is preferably 70 parts by weight or more, more preferably 120 parts by weight or more, based on 100 parts by weight of the raw rubber. Also, the addition amount of all fillers is preferably 200 parts by weight or less, more preferably 150 parts by weight or less, based on 100 parts by weight of the raw rubber. The addition amount of fillers other than white carbon (when containing a plurality of types of fillers other than white carbon, the total amount of all of them. The same applies hereinafter.) is preferably 50 parts by weight or more, more preferably 100 parts by weight or more, based on 100 parts by weight of the raw rubber. Also, the addition amount of fillers other than white carbon is preferably 150 parts by weight or less, more preferably 130 parts by weight or less, based on 100 parts by weight of the raw rubber. Since bamboo powder not only suppresses the temperature rise but also functions as a filler, in the elastic chip of this embodiment containing bamboo powder, the content of the filler can be reduced compared with a general elastic chip.

[0037] Incidentally, carbon black is also known as a rubber filler, but the amount of carbon black added to the elastic chip according to the present invention is preferably 3 parts by weight or less, more preferably 1 part by weight or less, and even more preferably substantially 0 parts by weight (not added) with respect to 100 parts by weight of the raw rubber. This is because adding carbon black may make it difficult to suppress the temperature rise of the elastic chip.

[0038] As processing aids, for example, fatty acids, fatty acid derivatives (such as fatty acid esters, metal soaps, hydroxy fatty acids, fatty acid amides, etc.), aliphatic alcohols, resins (such as petroleum resins, synthetic resins, low molecular weight polymers, etc.) can be used. Among them, it is preferable to use processing aids having a fatty chain in the molecule, such as fatty acids (for example, stearic acid, etc.), fatty acid derivatives, aliphatic alcohols (hereinafter sometimes referred to as "aliphatic processing aids"). Thereby, the dispersibility of bamboo powder in the elastic chip can be enhanced. The fatty chain of the aliphatic processing aid may be saturated or unsaturated, but is preferably a saturated fatty chain. The number of carbon atoms in the fatty chain is not limited, but is preferably 10 or more and 40 or less, and more preferably 15 or more and 25 or less. The processing aids contained in the elastic chip may be only one type or two or more types.

[0039] The addition amount of the processing aid (when including multiple types of processing aids, the total amount of all processing aids) is not limited, but is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more with respect to 100 parts by weight of the raw rubber. Also, it is preferably 10 parts by weight or less, more preferably 8 parts by weight or less with respect to 100 parts by weight of the raw rubber. When using an aliphatic processing aid as the processing aid, the addition amount (when including multiple types of aliphatic processing aids, the total amount of all aliphatic processing aids) is preferably 0.3 parts by weight or more, more preferably 0.5 parts by weight or more. Also, it is preferably 4 parts by weight or less, more preferably 2 parts by weight or less.

[0040] As the crosslinking accelerator, for example, thiazole-based vulcanization accelerators, thiourea-based vulcanization accelerators, thiuram-based vulcanization accelerators, dithiocarbamic acid-based vulcanization accelerators, guanidine-based vulcanization accelerators, etc. can be used. The crosslinking accelerator contained in the elastic chip may be only one kind or two or more kinds. The addition amount of the crosslinking accelerator (when including a plurality of kinds of crosslinking accelerators, the total amount of all crosslinking accelerators) is not limited, but is preferably 2 parts by weight or more, more preferably 3 parts by weight or more, based on 100 parts by weight of the raw rubber. Also, it is preferably 10 parts by weight or less, more preferably 5 parts by weight or less.

[0041] 3. Manufacturing method of elastic chip The elastic chip of the present embodiment can be manufactured by going through a mixing step, a crosslinking step, and a chipping step.

[0042] 3.1 Mixing step The mixing step is a step of obtaining a pre-crosslinked composition by mixing the raw rubber in an uncrosslinked or semi-crosslinked state, bamboo powder, and a crosslinking agent. In the mixing step, all the raw materials of the pre-crosslinked composition can also be mixed at once. However, in the present embodiment, the raw materials of the pre-crosslinked composition are mixed in a plurality of stages. Specifically, the mixing step in the present embodiment includes a bamboo powder mixing step of adding bamboo powder to the raw rubber and kneading, and a crosslinking agent mixing step of adding a crosslinking agent to the mixture obtained in the bamboo powder mixing step and kneading. Thereby, the dispersibility of the bamboo powder in the pre-crosslinked composition (in the elastic chip) can be enhanced. When the elastic chip further contains a vulcanization accelerator, a vulcanization accelerator mixing step of adding a vulcanization accelerator to the mixture obtained in the bamboo powder mixing step can be further passed through between the bamboo powder mixing step and the crosslinking agent mixing step.

[0043] The elastic chip in this embodiment contains a coupling agent and white carbon, and the timing of mixing these into the raw rubber is not particularly limited. In this embodiment, the coupling agent and white carbon are mixed into the raw rubber substantially simultaneously with the bamboo powder in the bamboo powder mixing step. By adding the coupling agent before the crosslinking step, crosslinking can be performed in a state where the bamboo powder and the raw rubber are firmly bonded. The coupling agent and white carbon may be mixed into the raw rubber before the bamboo powder.

[0044] When the elastic chip contains fillers other than white carbon, processing aids, plasticizers, zinc oxide (or / and activated zinc oxide), crosslinking accelerators, thickeners, anti-aging agents, coloring materials, etc., the timing of mixing these is not limited either. These can be mixed into the raw rubber, for example, substantially simultaneously with the bamboo powder in the bamboo powder mixing step. The fillers and processing aids can also be mixed into the raw rubber, for example, substantially simultaneously with the crosslinking agent in the crosslinking agent mixing step.

[0045] 3.2 Crosslinking Step The crosslinking step is a step of crosslinking the pre-crosslinking composition obtained in the mixing step to obtain a crosslinked product of the pre-crosslinking composition (hereinafter sometimes referred to as "rubber mass"). The crosslinking conditions vary depending on the type of raw rubber, crosslinking agent, etc., and are not particularly limited. When using a vulcanizable raw rubber and sulfur or a sulfur compound as the crosslinking agent (vulcanizing agent), the vulcanization temperature is preferably 100°C or higher, more preferably 130°C or higher. Also, the vulcanization temperature is preferably 200°C or lower, more preferably 180°C or lower. Vulcanization can be carried out in a vulcanizing kettle or using a press molding machine. The pressure when vulcanizing in a vulcanizing kettle is usually 1 atm (atmospheric pressure) or more and 8 atm or less. The pressure when vulcanizing using a press molding machine is usually 3 MPa or more and 20 MPa or less. The vulcanization time is not limited, but when vulcanizing in a vulcanizing kettle, it is usually about 30 to 120 minutes, and when vulcanizing using a press molding machine, it is usually about 5 to 30 minutes.

[0046] 3.3 Chip Formation Process The chip formation process is a process of processing the rubber mass obtained in the crosslinking process into a chip shape (granular shape). In this embodiment, a crusher having a plurality of blade-shaped blades is used to process the rubber mass into a chip shape. The crusher is attached with a screen provided with a large number of openings having a predetermined size, and only the granular material crushed to a size that can pass through the openings of the screen comes out. The size of the granular material (elastic chip) thus obtained is not limited, but is preferably 5 mm or less, and more preferably 3.5 mm or less. The lower limit of the size of the granular material (elastic chip) is not limited, but is usually 0 mm or more.

[0047] In this embodiment, the granular material obtained in the chip formation process is used as an elastic chip as it is. However, in other embodiments, a coating process of applying a coating (for example, a resin coating) to the granular material obtained in the chip formation process can be further performed.

[0048] 4. Rubber Physical Properties of the Rubber Composition The tensile strength at break of the rubber composition forming the elastic chip (the tensile strength at break measured in accordance with JIS K6251. The same applies hereinafter.) is not limited, but if it is too small, it may be difficult to increase the strength of the elastic chip. For this reason, the tensile strength at break of the rubber composition is preferably 2 MPa or more, and more preferably 2.5 MPa or more. The upper limit of the tensile strength at break of the rubber composition is not limited, but is usually 5 MPa or less.

[0049] The elongation at break of the rubber composition forming the elastic chip (the elongation at break measured in accordance with JIS K6251. The same applies hereinafter.) is not particularly limited. However, if the elongation at break is too small, the elastic chip may become too brittle, and if the elongation at break is too large, the elastic chip may become too soft and it may be difficult to improve the cushioning property and durability. For this reason, the elongation at break of the rubber composition is preferably 200% or more and 400% or less, and more preferably 250% or more and 300% or less.

[0050] The tear strength of the rubber composition for forming the elastic chip (the tear strength measured in accordance with JIS K6251; the same shall apply hereinafter) is not particularly limited, but if it is too small, it may be difficult to increase the strength of the elastic chip. Therefore, the tear strength of the rubber composition is preferably 10 N / mm or more, and more preferably 12 N / mm or less. The upper limit of the tear strength of the rubber composition is not limited, but is usually 20 N / mm or less.

[0051] The rubber hardness of the rubber composition for forming the elastic chip (Shore A rubber hardness; the same shall apply hereinafter) is not particularly limited. However, if the rubber hardness is too small, it may be difficult to enhance the cushioning property and durability of the elastic chip, and if the rubber hardness is too large, it may be difficult to enhance the elasticity of the elastic chip. Therefore, the rubber hardness of the rubber composition is preferably 50 or more and 80 or less, and more preferably 60 or more and 70 or less.

[0052] 4. Applications The elastic chip according to the present invention can be used, for example, as an artificial turf with a filler for filling between the piles of artificial turf for lawns. The filling of the elastic chip into the piles of artificial turf for lawns is usually performed by spraying the elastic chips in a loose state onto the piles of artificial turf for lawns.

[0053] In addition, the elastic chip according to the present invention can also be used as a covering material for the ground or a structure. More specifically, for example, by mixing the elastic chip with a curable binder and molding it into a tile shape or a block shape, a tile-shaped or block-shaped paving material can be produced. Alternatively, by mixing the elastic chip with a binder and applying it to the ground or a structure (for example, a wall, a fence, a playground equipment, etc.), an elastic coating layer covering the ground or the structure can also be formed. As the binder used in these cases, for example, a urethane-based binder containing polyol and isocyanate can be used.

Examples

[0054] Hereinafter, more specific experimental examples will be given to explain the elastic chip according to the present invention in more detail. However, the embodiments of the present invention are not limited to the following examples.

[0055] [Irradiation Test] In order to verify the temperature rise suppression function of the elastic chip, an irradiation test was conducted in accordance with (4) Appendix-3 "Indoor Irradiation Test Method for Heat Insulating Pavement" published in the "Technical Data on Heat Insulating Pavement" revised on September 1, 2011 by the Road Surface Temperature Rise Suppression Pavement Research Group. However, the irradiation test was conducted at room temperature (about 25°C) in a normal room instead of a constant temperature room.

[0056] [Preparation of Samples] First, the elastic chip was manufactured with the formulation shown in Table 1 below. As the silane coupling agent, 3-mercaptopropyltrimethoxysilane was used. As the bamboo powder, pulverized and dried bamboo passed through a sieve with a mesh size of approximately 150 μm (materials with a size of approximately 150 μm or less) was used. The size of the elastic chip was set to 0 mm or more and 3.5 mm or less. The manufactured elastic chip was mixed with a urethane-based binder at about 3 to 10% by weight, poured into a press mold, and press-molded into a tile shape. The size of the obtained tile-shaped sample (Sample 1) was approximately 300 mm in length, 300 mm in width, and 10 mm in thickness. As comparative samples, a commercially available EPDM-colored rubber chip (brown type) molded into a tile shape in the same manner as Sample 1 (Comparative Sample 1), and a heat-insulating colored rubber chip (brown type) containing 10 parts by weight of a heat-insulating pigment and 16 parts by weight of white carbon with respect to 100 parts by weight of EPDM, molded into a tile shape in the same manner as Sample 1 (Comparative Sample 2) were prepared.

[0057] [Table 1]

[0058] [Irradiation Test] Figure 1 is a schematic diagram showing the state of conducting the irradiation test. The irradiation test was conducted according to the following procedure. [1] The tile-shaped sample (Sample 1, Comparative Sample 1, or Comparative Sample 2) obtained by the above method was left standing in a heat insulating material made of styrofoam as shown in Fig. 1. The heat insulating material has a substantially flat bottom surface portion and side surface portions that can surround the four sides of the tile-shaped sample. The size of the recess surrounded by the side surface portions is substantially the same as that of the tile-shaped sample (that is, the size of the recess is approximately 300 mm in length and approximately 300 mm in width, and the depth of the recess was approximately 50 mm). The thickness of the bottom surface of the heat insulating material was approximately 50 mm. [2] Using a lamp stand (not shown), a beam lamp was installed above the tile-shaped sample. As the beam lamp, an incandescent lamp diffused type BRF110V150W or 120W (manufactured by Toshiba Lighting & Technology) was used. Using a weight (not shown), the position of the beam lamp was adjusted so that the center of the beam lamp was arranged directly above the substantially vertical direction of the horizontal center point of the tile-shaped sample, and the inclination of the beam lamp was adjusted so that the irradiation surface of the beam lamp was substantially horizontal. The distance from the upper surface of the tile-shaped sample to the irradiation surface of the beam lamp was set to approximately 600 mm. [3] A measuring element (thermocouple) for measuring the surface temperature of the tile-shaped sample was attached to approximately the center of the upper surface of the tile-shaped sample. [4] The four sides of the heat insulating material were surrounded by a cardboard cover. Thereby, the convection of the surrounding air can be suppressed. [5] The beam lamp was turned on and the temperature measurement was started. The temperature was measured every 10 minutes for the first 60 minutes and then every 30 minutes. The measurement was completed 90 minutes after the start of lighting.

[0059] (Results) Fig. 2 is a graph showing the results of the irradiation test. As shown in Fig. 2, even when the tile-shaped sample of Sample 1 was irradiated for 90 minutes under the above conditions, its surface temperature was less than 50°C. In contrast, for Comparative Sample 1 and Comparative Sample 2, the surface temperature after 90 minutes of irradiation exceeded 50°C.

[0060] [Physical Property Test] In order to verify the rubber physical properties of the elastic chip (rubber composition), the physical property measurement of the rubber composition was carried out. Specifically, an unvulcanized composition was prepared according to the formulation shown in Table 2 below, and vulcanization was carried out at 160 °C and 15 MPa for 10 minutes using a press molding machine. As the silane coupling agent, 3-mercaptopropyltrimethoxysilane was used. As the bamboo powder, pulverized and dried bamboo passed through a sieve with an aperture of approximately 150 μm (those with a size of approximately 150 μm or less) was used. For the vulcanized samples (Sample 2, Sample 3), in accordance with JIS K6251, the tensile strength at break, elongation at break, tear strength, and rubber hardness were measured. The results are shown in Table 2 below.

[0061]

Table 2

[0062] As shown in Table 2, in Sample 2 containing the silane coupling agent, the tensile strength at break and tear strength were improved compared to Sample 3 not containing the silane coupling agent.

Claims

1. An elastic chip formed of a rubber composition containing a rubber component and bamboo powder, wherein the rubber component is mainly a thermosetting elastomer.

2. The elastic chip according to claim 1, further comprising one or more coupling agents selected from the group consisting of silane-based coupling agents, aluminate-based coupling agents, and titanate-based coupling agents.

3. The elastic chip according to claim 2, wherein the coupling agent has a mercapto group.

4. The elastic chip according to claim 1, further comprising white carbon.

5. An artificial turf with a filler filled between the piles of the pile for artificial turf, wherein the elastic chip according to any one of claims 1 to 4 is used.

6. A covering material for the ground or a structure using the elastic chip according to any one of claims 1 to 4.

7. A mixing step of obtaining a pre-crosslinking composition by mixing an uncrosslinked or semi-crosslinked raw rubber, bamboo powder, and a crosslinking agent, and a crosslinking step of crosslinking the pre-crosslinking composition. A method for manufacturing an elastic chip passing through these steps. ​

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