Artificial mushroom structure

Abstract

Impact cushioning particles contain a poly(3-hydroxybutyrate)-based resin component. The poly(3-hydroxybutyrate)-based resin component contains a copolymer (A) component, and the copolymer (A) component contains a copolymer (A-1) and / or a copolymer (A-2). The impact cushioning particles are suitably used particularly in artificial lawn or pavement.　Copolymer (A-1) is a copolymer of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit the content of which is 1-10 mol% (exclusive of 10). Copolymer (A-2) is a copolymer of a 3-hydroxybutyrate unit and another hydroxyalkanoate unit the content of which is at least 24 mol%.

Description

Impact-absorbing particles, artificial turf structure, and pavement

[0001] The present invention relates to shock-absorbing particles that are laid on floor surfaces to absorb shocks such as those caused by walking or landing during sports, and to artificial turf structures or pavements that utilize the particles.

[0002] Impact-resistant particles made of rubber, elastomers, resins, etc. are used in conjunction with artificial turf on floors at sports facilities and other facilities to cushion the impact of people landing on them. However, if these particles adhere to the soles of shoes or are scattered outside the facility due to the impact of being kicked, they are released into the environment and are eventually carried to the ocean via rivers and other streams, causing marine pollution as microplastics.

[0003] In response to such environmental pollution in the ocean and elsewhere, attempts have been made to use coconut shells (see Patent Document 1), cork, wood chips, etc., but these materials can absorb water, causing the facility to remain wet for a long time, and can also reduce impact resistance.

[0004] Patent No. 6849454

[0005] To address environmental pollution caused by impact-absorbing particles, the use of biodegradable resins such as polylactic acid has been considered; however, polylactic acid is hard and therefore lacks impact absorption properties, and its biodegradability in the environment, especially in the ocean, is low, so it has not led to a solution to the problem of environmental pollution.

[0006] In view of the above-mentioned current situation, an object of the present invention is to provide particles imparting impact cushioning properties that are biodegradable in the ocean and have excellent impact absorption properties.

[0007] As a result of intensive research aimed at solving the above problems, the present inventors have found that particles containing a poly(3-hydroxybutyrate)-based resin component having a specific structure not only have good biodegradability in the ocean but also have the impact absorption properties required for materials used to impart impact cushioning to paved roads, artificial turf, etc., and have thus completed the present invention.

[0008] That is, the present invention relates to impact-cushioning particles containing a poly(3-hydroxybutyrate)-based resin component, wherein the poly(3-hydroxybutyrate)-based resin component contains a copolymer (A) component, and the copolymer (A) component contains the following copolymer (A-1) and / or the following copolymer (A-2): Copolymer (A-1): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 mol % or more and less than 10 mol % Copolymer (A-2): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol % or more

[0009] According to the present invention, it is possible to provide impact-absorbing particles that are biodegradable in the ocean and have excellent impact absorption properties. The impact-absorbing particles can be particularly suitably used in artificial turf or pavement.

[0010] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. One embodiment of the present invention relates to impact-cushioning particles containing a poly(3-hydroxybutyrate)-based resin component.

[0011] (Poly(3-hydroxybutyrate)-Based Resin Component) The poly(3-hydroxybutyrate) resin component may be a single poly(3-hydroxybutyrate)-based resin or a mixture of two or more poly(3-hydroxybutyrate)-based resins. However, in terms of excellent impact absorption properties and ease of processing into particles, a mixture of at least two types of poly(3-hydroxybutyrate)-based resins that differ from each other in the types of constituent monomers and / or the content ratios of the constituent monomers is preferred.

[0012] The poly(3-hydroxybutyrate) resin is a polymer having a 3-hydroxybutyrate unit, specifically a polymer containing a unit represented by the following general formula (1): [—CH(CH ３ )-CH ２ -CO-O-] (1)

[0013] The poly(3-hydroxybutyrate) resin is preferably a poly(3-hydroxybutyrate) resin produced by a microorganism, in which all 3-hydroxybutyrate units are contained as (R)-3-hydroxybutyrate units.

[0014] The poly(3-hydroxybutyrate) resin preferably contains 3-hydroxybutyrate units (particularly units represented by general formula (1)) in an amount of 50 mol % or more, more preferably 60 mol % or more, and even more preferably 70 mol % or more of the total structural units. The poly(3-hydroxybutyrate) resin may contain only one or more types of 3-hydroxybutyrate units as structural units of the polymer, or may contain one or more types of 3-hydroxybutyrate units as well as other units (e.g., 4-hydroxyalkanoate units).

[0015] The poly(3-hydroxybutyrate) resin is preferably a homopolymer or copolymer containing 3-hydroxybutyrate (hereinafter sometimes referred to as 3HB) units. In particular, it is preferable that all of the 3-hydroxybutyrate units are (R)-3-hydroxybutyrate units. Furthermore, the poly(3-hydroxybutyrate) resin is preferably a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units.

[0016] Specific examples of poly(3-hydroxybutyrate)-based resins include poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxypropionate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (abbreviation: P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (abbreviation: P3HB3HH), Examples of suitable polyhydroxybutyrates include poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly(3-hydroxybutyrate-co-3-hydroxynonanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-3-hydroxyundecanoate), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (abbreviation: P3HB4HB). In particular, from the viewpoints of particle productivity and mechanical properties, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate) is preferred.

[0017] When the poly(3-hydroxybutyrate) resin component contains a copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, the average content ratio of 3-hydroxybutyrate units and other hydroxybutyrate units to all monomer units constituting the poly(3-hydroxybutyrate) resin component is, from the viewpoint of achieving both particle productivity and mechanical properties, preferably 3HB units / other hydroxyalkanoate units = 93 / 7 to 80 / 30 (mol % / mol %), more preferably 92 / 8 to 72 / 28 (mol % / mol %), even more preferably 90 / 10 to 75 / 25 (mol % / mol %), still more preferably 88 / 12 to 76 / 24 (mol % / mol %), particularly preferably 86 / 14 to 78 / 22 (mol % / mol %), and most preferably 84 / 16 to 80 / 20 (mol % / mol %).

[0018] When the poly(3-hydroxybutyrate)-based resin component contains a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymer, which is a copolymer of 3-hydroxybutyrate units and 3-hydroxyhexanoate (3HH) units, the average content ratio of 3-hydroxybutyrate units and other hydroxyalkanoate units to all monomer units constituting the poly(3-hydroxybutyrate)-based resin component is preferably 3HB units / 3HH units=90 / 10 to 75 / 25 (mol % / mol %), even more preferably 88 / 12 to 76 / 24 (mol % / mol %), particularly preferably 86 / 14 to 78 / 22 (mol % / mol %), and most preferably 84 / 16 to 80 / 20 (mol % / mol %).

[0019] The average content ratio of each monomer unit in all monomer units constituting the poly(3-hydroxybutyrate)-based resin component can be determined by a method known to those skilled in the art, for example, the method described in paragraph

[0047] of WO 2013 / 147139. The average content ratio means the molar ratio of each monomer unit in all monomer units constituting the poly(3-hydroxybutyrate)-based resin component, and when the poly(3-hydroxybutyrate)-based resin component is a mixture of two or more poly(3-hydroxybutyrate)-based resins, it means the molar ratio of each monomer unit contained in the entire mixture.

[0020] The weight average molecular weight of the poly(3-hydroxybutyrate)-based resin component is not particularly limited, but from the viewpoint of achieving both productivity and mechanical properties of the particles, it is preferably 200,000 to 2,000,000, more preferably 250,000 to 1,500,000, and even more preferably 300,000 to 1,000,000.

[0021] Furthermore, when the poly(3-hydroxybutyrate)-based resin component is a mixture of two or more poly(3-hydroxybutyrate)-based resins, the weight-average molecular weight of each poly(3-hydroxybutyrate)-based resin is not particularly limited. However, for example, when a highly crystalline poly(3-hydroxybutyrate)-based resin and a low-crystalline poly(3-hydroxybutyrate)-based resin are used in combination as described below, the weight-average molecular weight of the highly crystalline poly(3-hydroxybutyrate)-based resin is preferably 200,000 to 1,000,000, more preferably 220,000 to 800,000, and even more preferably 250,000 to 600,000, from the viewpoint of achieving both particle productivity and mechanical properties. On the other hand, the weight-average molecular weight of the low-crystalline poly(3-hydroxybutyrate)-based resin is preferably 200,000 to 2,500,000, more preferably 250,000 to 2,300,000, and even more preferably 300,000 to 2,000,000, from the viewpoint of achieving both particle productivity and mechanical properties.

[0022] The weight-average molecular weight of the poly(3-hydroxybutyrate) resin or poly(3-hydroxybutyrate) resin component can be measured in terms of polystyrene using gel permeation chromatography (HPLC GPC system manufactured by Shimadzu Corporation) using a chloroform solution. As the column for the gel permeation chromatography, a column appropriate for measuring the weight-average molecular weight may be used.

[0023] As the at least two poly(3-hydroxybutyrate)-based resins differing from each other in the type and / or content ratio of the constituent monomers, it is preferable to use a combination of at least one highly crystalline poly(3-hydroxybutyrate)-based resin and at least one low-crystalline poly(3-hydroxybutyrate)-based resin. Generally, highly crystalline poly(3-hydroxybutyrate)-based resins have excellent productivity but poor mechanical strength, while low-crystalline poly(3-hydroxybutyrate)-based resins have poor productivity but excellent mechanical properties. It is presumed that when the two resins are mixed, the highly crystalline poly(3-hydroxybutyrate)-based resin forms fine resin crystal particles, while the low-crystalline poly(3-hydroxybutyrate)-based resin forms tie molecules that connect the resin crystal portions. Using these resins in combination can improve the impact absorption, abrasion resistance, and heat resistance of the particles.

[0024] The content of 3-hydroxybutyrate units in the high-crystalline poly(3-hydroxybutyrate) resin is preferably higher than the average content of 3-hydroxybutyrate units in all monomer units constituting the poly(3-hydroxybutyrate) resin component. Also, the content of 3-hydroxybutyrate units in the low-crystalline poly(3-hydroxybutyrate) resin is preferably lower than the average content of 3-hydroxybutyrate units in all monomer units constituting the poly(3-hydroxybutyrate) resin component.

[0025] Specifically, the poly(3-hydroxybutyrate)-based resin component contained in the impact-cushioning particles according to this embodiment contains a copolymer (A) component, and the copolymer (A) component contains the following copolymer (A-1) and / or the following copolymer (A-2): Copolymer (A-1): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of the other hydroxyalkanoate units is 1 mol % or more but less than 10 mol % Copolymer (A-2): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of the other hydroxyalkanoate units is 24 mol % or more

[0026] The content of the other hydroxybutyrate units in the copolymer (A-1) is preferably from 1 to 9 mol %, more preferably from 1 to 8 mol %, and even more preferably from 1 to 6 mol %.

[0027] The copolymer (A-1) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0028] The content of the other hydroxyalkanoate units in the copolymer (A-2) is preferably from 24 to 99 mol %, more preferably from 24 to 50 mol %, even more preferably from 24 to 35 mol %, and particularly preferably from 24 to 30 mol %.

[0029] The copolymer (A-2) is preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) or poly(3-hydroxybutyrate-co-4-hydroxybutyrate), more preferably poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

[0030] From the viewpoint of particle processability and strength, the content of copolymer (A-1) and / or copolymer (A-2) is preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more, relative to the total weight of the poly(3-hydroxybutyrate)-based resin component. The upper limit may be 100% by weight or less. The poly(3-hydroxybutyrate)-based resin component may contain a poly(3-hydroxybutyrate)-based resin that does not fall into either copolymer (A-1) or copolymer (A-2).

[0031] The proportion of each copolymer used relative to the total amount of copolymer (A-1) and copolymer (A-2) is not particularly limited, but from the viewpoint of the processability and strength of the particles, the former is preferably 50% by weight or more and 95% by weight or less, and the latter is preferably 5% by weight or more and 50% by weight or less, more preferably 60% by weight or more and 90% by weight or less, and the latter is more preferably 10% by weight or more and 40% by weight or less, and even more preferably 70% by weight or more and 85% by weight or less, and the latter is more preferably 15% by weight or more and 30% by weight or less.

[0032] The melting point of the poly(3-hydroxybutyrate) resin component is preferably 120 to 170°C, more preferably 130 to 160°C, from the viewpoint of the processability and strength of the particles.

[0033] The method for producing poly(3-hydroxybutyrate)-based resins is not particularly limited, and may be a production method using chemical synthesis or a production method using a microorganism. Among these, a production method using a microorganism is preferred. Known methods can be applied to the production method using a microorganism. For example, known bacteria that produce copolymers of 3-hydroxybutyrate and other hydroxyalkanoates include Aeromonas caviae, which produces P3HB3HV and P3HB3HH, and Alcaligenes eutrophus, which produces P3HB4HB. In particular, with regard to P3HB3HH, in order to increase the productivity of P3HB3HH, Alcaligenes eutrophus AC32 strain (FERM BP-6038) (T. Fukui, Y. Doi, J. Bateriol., 179, pp. 4821-4830 (1997)) or the like into which genes encoding P3HA synthases have been introduced is more preferred, and microbial cells obtained by culturing these microorganisms under appropriate conditions and allowing P3HB3HH to accumulate within the cells are used. In addition to the above, genetically modified microorganisms into which various poly(3-hydroxybutyrate) resin synthesis-related genes have been introduced may be used depending on the poly(3-hydroxybutyrate) resin to be produced, or the culture conditions, including the type of substrate, may be optimized.

[0034] The method for obtaining a blend of two or more poly(3-hydroxybutyrate) resins is not particularly limited, and may be a method for obtaining a blend by microbial production or a method for obtaining a blend by chemical synthesis. Alternatively, a blend may be obtained by melt-kneading two or more resins using an extruder, kneader, Banbury mixer, roll mill, or the like, or by dissolving two or more resins in a solvent, mixing, and drying the resins.

[0035] (Other Resins) The impact-absorbing particles according to this embodiment may contain other resins besides poly(3-hydroxybutyrate)-based resins, as long as the effects of the invention are not impaired. Examples of such other resins include aliphatic polyester-based resins such as polybutylene succinate adipate, polybutylene succinate, polycaprolactone, and polylactic acid, and aliphatic aromatic polyester-based resins such as polybutylene adipate terephthalate, polybutylene sebacate terephthalate, and polybutylene azelate terephthalate. Only one type of other resin may be contained, or two or more types may be contained.

[0036] The content of the other resin is not particularly limited, but is preferably 30 parts by weight or less, more preferably 20 parts by weight or less, even more preferably 10 parts by weight or less, and particularly preferably 5 parts by weight or less, relative to 100 parts by weight of the total poly(3-hydroxybutyrate)-based resin components. It may even be 1 part by weight or less. The lower limit of the content of the other resin is not particularly limited, and may even be 0 part by weight.

[0037] (Plasticizer) The impact-cushioning particles according to this embodiment preferably contain a plasticizer in addition to the poly(3-hydroxybutyrate)-based resin component. By incorporating a plasticizer, it is possible to provide particles that have better impact absorption properties while still containing the poly(3-hydroxybutyrate)-based resin component.

[0038] The plasticizer is not particularly limited, but from the viewpoint of compatibility with the poly(3-hydroxybutyrate)-based resin component, it is preferable to use an ester compound having an ester bond in the molecule.

[0039] Examples of ester compounds that can be used as plasticizers include modified glycerin ester compounds, dibasic acid ester compounds, adipate ester compounds, polyether ester compounds, benzoate ester compounds, citrate ester compounds, isosorbide ester compounds, and polycaprolactone compounds. Among these, modified glycerin ester compounds, dibasic acid ester compounds, adipate ester compounds, polyether ester compounds, and isosorbide ester compounds are preferred. The ester compounds can be used alone or in combination of two or more. When two or more compounds are used in combination, the mixing ratio of the ester compounds can be appropriately adjusted.

[0040] Specific examples of modified glycerin ester compounds include glycerin monoesters, diesters, and triesters, but glycerin triesters are preferred from the viewpoint of compatibility with poly(3-hydroxybutyrate) resin components. Among glycerin triesters, glycerin diacetomonoesters are particularly preferred. Specific examples of glycerin diacetomonoesters include glycerin diacetomonolaurate, glycerin diacetomonooleate, glycerin diacetomonostearate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate. Examples of the modified glycerin compounds include Riken Vitamin Co., Ltd.'s "Rikemal" PL series and "BIOCIZER."

[0041] Specific examples of dibasic acid ester compounds include dibutyl adipate, diisobutyl adipate, bis(2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, bis(2-ethylhexyl) azelate, dibutyl sebacate, bis(2-ethylhexyl) sebacate, diethyl succinate, and mixed-group dibasic acid ester compounds.

[0042] Examples of the adipate compounds include diethylhexyl adipate, dioctyl adipate, and diisononyl adipate.

[0043] Examples of polyether ester compounds include polyethylene glycol dibenzoate, polyethylene glycol dicaprylate, and polyethylene glycol diisostearate.

[0044] As the ester compound, a modified glycerin-based ester compound is preferred, a glycerin triester is more preferred, a glycerin diacetomonoester is even more preferred, and glycerin diacetomonolaurate is particularly preferred, from the viewpoints of cost, versatility, and high biomass content.

[0045] The content of the plasticizer can be appropriately determined taking into consideration the productivity and mechanical properties of the particles. It is preferably 10 to 70 parts by weight, more preferably 20 to 60 parts by weight, and even more preferably 30 to 50 parts by weight, per 100 parts by weight of the poly(3-hydroxybutyrate) resin component. By setting the content of the plasticizer within the above range, impact-absorbing particles with favorable productivity and mechanical properties can be obtained. (Additives) The impact-absorbing particles according to this embodiment may contain additives within a range that does not impair the effects of the invention. Examples of additives that can be used depending on the purpose include crystallization nucleating agents, lubricants, plasticizers, antistatic agents, flame retardants, conductive agents, heat insulating agents, crosslinking agents, antioxidants, UV absorbers, colorants, inorganic fillers, organic fillers, and hydrolysis inhibitors. Biodegradable additives are particularly preferred.

[0046] Examples of crystallization nucleating agents include poly(3-hydroxybutyrate), which is a homopolymer of 3-hydroxybutyrate, pentaerythritol, orotic acid, aspartame, cyanuric acid, glycine, zinc phenylphosphonate, and boron nitride. Among these, poly(3-hydroxybutyrate) or pentaerythritol is preferred because of its particularly excellent effect of promoting the crystallization of poly(3-hydroxybutyrate)-based resin components. Note that poly(3-hydroxybutyrate) can also fall under the category of the poly(3-hydroxybutyrate)-based resin component described above.

[0047] The amount of the crystallization nucleating agent used is not particularly limited, but is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, and even more preferably 0.7 to 1.5 parts by weight, relative to 100 parts by weight of the total of the poly(3-hydroxybutyrate) resin components. One type of crystallization nucleating agent may be used, or two or more types may be used, and the usage ratio can be appropriately adjusted depending on the purpose.

[0048] Examples of lubricants include behenamide, oleamide, erucamide, stearamide, palmitamide, N-stearylbehenamide, N-stearylerucamide, ethylenebisstearamide, ethylenebisoleamide, ethylenebiserucamide, ethylenebislauricamide, ethylenebiscapricamide, p-phenylenebisstearamide, polycondensates of ethylenediamine, stearic acid, and sebacic acid, etc. Among these, behenamide and erucamide are preferred because of their particularly excellent lubricating effect on poly(3-hydroxybutyrate)-based resin components.

[0049] The amount of lubricant used is not particularly limited, but is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 3 parts by weight, and even more preferably 0.1 to 1.5 parts by weight, relative to 100 parts by weight of the total poly(3-hydroxybutyrate) resin components. One type of lubricant may be used, or two or more types may be used, and the usage ratio can be appropriately adjusted depending on the purpose.

[0050] (Particles) The shape of the impact-absorbing particles according to this embodiment is not particularly limited as long as it does not impair the effects of the invention, but for example, approximately spherical, approximately cylindrical (approximately disc-like), approximately polygonal (approximately polygonal disc-like), etc. are preferred. The particle size of the impact-absorbing particles can be adjusted as appropriate. For example, when used by filling artificial turf, the number average value of the largest axis diameter among the vertical axis, horizontal axis, and width of a particle diameter is preferably 0.5 mm or more and 7 mm or less, more preferably 1 mm or more and 5 mm or less, even more preferably 2 mm or more and 4 mm or less, and even more preferably 2 mm or more and 3 mm or less. If the particle size is within the above range, it can prevent particles from flowing out, scattering, floating on water, etc. due to wind and rain.

[0051] The specific gravity of the impact-absorbing particles according to this embodiment is not particularly limited as long as it is within a range that does not impair the effects of the invention. However, for example, when used by filling artificial turf, it is preferable that the specific gravity be 1 or more, since this can prevent the particles from leaking, scattering, floating on water, etc. due to wind and rain.

[0052] The hardness of the impact-cushioning particles according to this embodiment is not particularly limited as long as it is within a range that does not impair the effects of the invention. However, for example, when used as an infill for artificial turf or a pavement, the particles are less likely to be compacted due to deformation caused by repeated treading, less likely to wear out shoe soles, and less likely to slip on rainy days, so the hardness measured by a hardness measurement method in accordance with the Type A method of JIS-K7215 is preferably 60 or more and 95 or less, and more preferably 70 or more and 90 or less.

[0053] (Method for Producing Particles) The impact-cushioning particles according to this embodiment can be produced by a known method. For example, a poly(3-hydroxybutyrate) resin component and other components are melt-kneaded in an extruder (a single-screw extruder or a twin-screw extruder), and then extruded in the form of strands through a die connected to the outlet of the extruder. The resin material is then cut to obtain pellets, i.e., particles, having a particle shape such as a cylindrical, elliptical, spherical, cubic, or rectangular parallelepiped shape.

[0054] The melt-kneading conditions are not particularly limited and can be set appropriately, but from the viewpoint of the thermal properties of the poly(3-hydroxybutyrate)-based resin component, it is preferable to melt-knead the resin at a temperature measured with a die thermometer in the range of 155° C. to 175° C. In addition, it is preferable to melt-knead the resin so that the residence time in the extruder is 60 seconds to 300 seconds.

[0055] (Use of Particles) The impact-absorbing particles according to this embodiment are particles used to provide impact-absorbing properties. In particular, they are suitable for use in applications where they are laid on road surfaces for the purpose of absorbing impacts during walking or sports. The laid impact-absorbing particles may or may not be fixed to the road surface. Examples of such road surfaces include artificial turf and pavement.

[0056] (Artificial turf structure) The artificial turf structure according to one aspect of the present embodiment is constructed by filling the impact-absorbing particles according to the present embodiment between the pile (grass threads) of the artificial turf. Conventional artificial turf can be used as the artificial turf, which is manufactured by planting resin pile into a base fabric. The impact-absorbing particles according to the present embodiment are filled between the pile.

[0057] The amount of particles to be packed can be set appropriately depending on the required elasticity and shock absorption, and is preferably enough to form a packed layer, more preferably a packed amount that is about half the pile height. Furthermore, from the viewpoint of preventing spillage and scattering, it is preferable that the thickness be such that the pile protrusion height h (the length from the surface of the packed layer to the tip of the pile) is 10 to 30 mm or more.

[0058] The impact absorption of the artificial turf structure according to this embodiment is preferably such that the attenuation rate is 40% or more, more preferably 50% or more, in the impact absorption test according to DIN 18032. There is no particular upper limit to the attenuation rate, but from the viewpoint of tread comfort (ease of release of the foot from the artificial turf structure), it is preferably less than 90%.

[0059] (Pavement) A pavement according to another aspect of this embodiment is, for example, a pavement in which the impact-cushioning particles according to this embodiment are filled into a portion of the pavement of a facility such as an athletics stadium or golf course. The structure of the elastic pavement portion of an athletics stadium generally consists of, from the surface, an embossed top layer, a top coat layer, an elastic base layer, an asphalt concrete layer, and a quarry layer. The impact-cushioning particles according to this embodiment can be filled into the embossed top layer and the elastic base layer.

[0060] The amount of particles to be filled can be set as appropriate, preferably to the extent that a filled layer is formed. Such a pavement can be produced by filling a portion of the pavement with particles by a known method.

[0061] The impact absorption of the pavement according to this embodiment is preferably such that the damping rate is 50% or more in the impact absorption test according to DIN 18032. There is no particular upper limit to the damping rate, but from the viewpoint of comfort (ease of release of the foot from the pavement), it is preferably less than 90%.

[0062] The following items are preferred embodiments of the present disclosure, but the present invention is not limited to them. [Item 1] Impact-cushioning particles containing a poly(3-hydroxybutyrate)-based resin component, wherein the poly(3-hydroxybutyrate)-based resin component contains a copolymer (A) component, and the copolymer (A) component contains the following copolymer (A-1) and / or the following copolymer (A-2). Copolymer (A-1): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of other hydroxyalkanoate units is 1 mol % or more but less than 10 mol %. Copolymer (A-2): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, in which the content of other hydroxyalkanoate units is 24 mol % or more. [Item 2] The impact cushioning particle according to Item 1, in which the content of the copolymer (A-1) and / or the copolymer (A-2) is 50 wt % or more relative to the total weight of the poly(3-hydroxybutyrate)-based resin component. [Item 3] The impact cushioning particle according to Item 1 or 2, in which the average content of hydroxyalkanoate units other than 3-hydroxybutyrate units in the poly(3-hydroxybutyrate)-based resin component is 10 to 25 mol %. [Item 4] The impact cushioning particle according to any one of items 1 to 3, wherein the poly(3-hydroxybutyrate)-based resin component has a melting point of 120 to 170°C. [Item 5] The impact cushioning particle according to any one of items 1 to 4, wherein the other hydroxyalkanoate units are 3-hydroxyhexanoate. [Item 6] The impact cushioning particle according to any one of items 1 to 5, wherein a plasticizer is contained in an amount of 10 to 70 parts by weight per 100 parts by weight of the poly(3-hydroxybutyrate)-based resin component in total. [Item 7] The impact cushioning particle according to item 6, wherein the plasticizer is a modified glycerin-based ester compound.[Item 8] The impact-cushioning particle according to Item 7, wherein the modified glycerin-based ester compound comprises at least one selected from the group consisting of glycerin diacetomonolaurate, glycerin diacetomonooleate, glycerin monoacetomonostearate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate. [Item 9] The impact-cushioning particle according to Item 8, wherein the modified glycerin-based ester compound comprises glycerin diacetomonolaurate. [Item 10] The impact-cushioning particle according to any one of Items 1 to 9, used in artificial turf or pavement. [Item 11] An artificial turf structure in which the impact-cushioning particles according to any one of Items 1 to 9 are filled between the piles of artificial turf. [Item 12] A pavement in which the impact-cushioning particles according to any one of Items 1 to 9 are filled into at least a portion of the pavement.

[0063] The present invention will be specifically explained below with reference to examples, but the technical scope of the present invention is not limited to these examples.

[0064] The materials used in the examples and comparative examples are as follows. [Poly(3-hydroxybutyrate)-based resin] P3HB3HH-1: P3HB3HH (average content ratio 3HB / 3HH = 96 / 3 (mol% / mol%), weight-average molecular weight 600,000 g / mol), produced in accordance with the method described in Example 2 of WO 2019 / 142845. P3HB3HH-2: P3HB3HH (average content ratio 3HB / 3HH = 72 / 28 (mol% / mol%), weight-average molecular weight 600,000 g / mol), produced in accordance with the method described in Example 9 of WO 2019 / 142845. P3HB3HH-3: P3HB3HH (average content ratio 3HB / 3HH=94 / 6 (mol % / mol %), weight average molecular weight 600,000 g / mol), produced in accordance with the method described in WO 2008 / 010296.

[0065] [Plasticizer] Glycerin diacetomonolaurate (BIOCIZER manufactured by Riken Vitamin Co., Ltd.) [Additives] Lubricant: behenic acid amide (BNT-22H manufactured by Nippon Fine Chemical Co., Ltd.).

[0066] The evaluation methods used in the Examples and Comparative Examples are described below. [Method for Evaluating Pellet Hardness] The pellets prepared in the Examples and Comparative Examples were filled between two polyimide films and then molded into a plate using a heat press (temperature: 165°C, pressure: 5 MPa, time: 5 minutes) to prepare a sample, and the durometer hardness was evaluated in accordance with JIS K7215 (Method A). The pellets were also crushed with fingers, and the hardness (flexibility) was qualitatively evaluated based on the feel according to the following evaluation criteria. <Evaluation Criteria> Hard: Not easily deformed even when strong force is applied. Good: Deformed, but elastic and easy to recover to its original shape. Soft: Deformed with weak force, weak elasticity making it difficult to recover to its original shape.

[0067] [Evaluation of Specific Gravity of Pellets] The specific gravity of the pellets produced in the Examples and Comparative Examples was measured in accordance with the underwater displacement method of JIS K7112.

[0068] [Impact absorption of structure (artificial turf)] The structures produced in the examples and comparative examples were evaluated for impact absorption using the DIN 18032 impact absorption test. Furthermore, the structures produced in the examples and comparative examples were placed on a concrete floor, and participants repeatedly walked barefoot on the same spot on the structure, and qualitative evaluation was performed according to the following evaluation criteria. <Evaluation criteria> Hard: No difference from walking on concrete, with impact felt in joints such as the knees when landing. Good: The structure absorbs impact while walking, making it difficult to feel impact when landing, and a moderate rebound force felt when the foot leaves the structure, making it easy to walk. Soft: The structure deforms with a weak force, and no impact is felt when landing, but the elasticity is weak, so resistance is felt when the foot leaves the structure, making it difficult to walk.

[0069] [Biodegradability of pellets in seawater] 1 g of each of the pellets prepared in the Examples and Comparative Examples was immersed in 300 ml of seawater, washed after 12 months, and weighed to evaluate the weight loss rate. The seawater used had been added with 0.15 g of ammonium chloride and 0.03 g of potassium phosphate monobasic, in accordance with ASTM D7081-05.

[0070] Example 1: A resin mixture was obtained by blending 50 parts by weight of P3HB3HH-1 and 50 parts by weight of P3HB3HH-2, adding 50 parts by weight of a plasticizer, and further blending. The resulting resin mixture was extruded into a φ26 mm co-rotating twin-screw extruder with a cylinder temperature set to 150°C and a die temperature set to 145°C. The extruded resin material was passed through a water bath filled with hot water at 40°C to solidify the strands, which were then cut with a pelletizer to obtain pellets of the resin mixture. The pellets had a roughly elliptical shape with a minor axis of 2 mm to 2.5 mm, a major axis of 2.8 to 3.0 mm, and a height of 1.0 to 1.5 mm. The hardness and specific gravity of the produced pellets were measured, and the results are shown in Table 1.

[0071] In addition, an artificial turf sample was prepared by laying 1 m x 1 m of artificial turf (grass height: 65 mm, pile type: polyethylene, pile shape: straight, diamond-shaped yarn / width 1 mm, pile thickness: 14,400 dtex, base fabric: plain woven PP fabric) on concrete and filling the spaces between the piles with the prepared pellets (filling layer: 3 mm).

[0072] Furthermore, a primer (polyoxypropylene glycol / methylene bisphenyl isocyanate addition polymer with Mw=1000: terminal isocyanate group content 16%) was applied to the asphalt surface at a basis weight of 300 g / m ２ A primer layer was formed by coating the pellets at a thickness of 30 mm with a mixture of 100 parts by weight of the pellets and 100 parts by weight of a binder (polyoxypropylene glycol / methylene bisphenyl isocyanate addition polymer with a Mw of 1000 and a terminal isocyanate group content of 9%) to form an elastic layer on the primer layer. The resulting artificial turf sample was evaluated for impact absorption, and the results are shown in Table 1.

[0073] (Examples 2 and 3) Pellets, artificial turf samples, and pavement samples were prepared in the same manner as in Example 1, except that the composition was changed according to the description in Table 1. The hardness, specific gravity, and impact absorption of the pellets were evaluated, and the results are shown in Table 1.

[0074] Comparative Example 1 Pellets, artificial turf samples, and pavement samples were prepared in the same manner as in Example 1, except that the resin mixture was changed to biodegradable polybutylene succinate (BioPBS (registered trademark) FZ91PM, manufactured by PTT MCC Biochem). The pellets were evaluated for hardness, specific gravity, and impact absorption, and the results are shown in Table 1.

[0075]

[0076] The following can be seen from Table 1. Examples 1 to 3 show that impact-cushioning particles using poly(3-hydroxybutyrate) resins have good hardness, excellent impact absorption, and excellent biodegradability in seawater. On the other hand, Comparative Example 1 shows that impact-cushioning particles using polybutylene succinate are too hard, have poor impact absorption, and do not exhibit biodegradability in seawater.

Claims

1. An artificial turf structure in which shock-absorbing particles containing a poly(3-hydroxybutyrate)-based resin component are filled between the piles of the artificial turf, The poly(3-hydroxybutyrate)-based resin component contains a copolymer (A), The copolymer (A) component contains the following copolymer (A-1) and / or the following copolymer (A-2), The poly(3-hydroxybutyrate) resin component has an average content of hydroxyalkanoate units other than 3-hydroxybutyrate units of 10 to 25 mol %. Copolymer (A-1): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 1 mol % or more and less than 10 mol %. Copolymer (A-2): A copolymer of 3-hydroxybutyrate units and other hydroxyalkanoate units, the content of which is 24 mol % or more.

2. The content of the copolymer (A-1) and / or the copolymer (A-2) is 50% by weight or more based on the total weight of the poly (3-hydroxybutyrate) resin component. The artificial turf structure according to claim 1.

3. The artificial turf structure according to claim 1, wherein the poly(3-hydroxybutyrate)-based resin component has a melting point of 120 to 170°C.

4. 2. The artificial turf structure of claim 1, wherein the other hydroxyalkanoate units are 3-hydroxyhexanoate.

5. The artificial turf structure according to claim 1, comprising 10 to 70 parts by weight of a plasticizer per 100 parts by weight of the poly(3-hydroxybutyrate)-based resin components.

6. 6. The artificial turf structure of claim 5, wherein the plasticizer is a modified glycerin-based ester compound.

7. The artificial turf structure according to claim 6, wherein the modified glycerin-based ester compound comprises at least one selected from the group consisting of glycerin diacetomonolaurate, glycerin diacetomonooleate, glycerin monoacetomonostearate, glycerin diacetomonocaprylate, and glycerin diacetomonodecanoate.

8. 8. The artificial turf structure of claim 7, wherein the modified glycerin-based ester compound comprises glycerin diacetomonolaurate.