Paving material

Abstract

The present invention provides a paving material capable of suitably suppressing warpage.　A paving material 1 includes a body portion 10 having a paired front surface F1 and rear surface F2. The paving material 1 is used with the rear surface F2 facing a ground surface. The direction orthogonal to the rear surface F2 is defined as the thickness direction T, and the direction in which the rear surface F2 is viewed from the front surface F1 among the thickness directions T is defined as a lower-side thickness direction T2. The body portion 10 is provided with at least one hollow part 11 and at least one rear-side recess 12 that is open in the lower-side thickness direction T2.

Description

paving materials

[0001] The present disclosure relates to paving materials.

[0002] Conventionally, the surface of the ground or the like has been covered with paving material. For example, Patent Document 1 discloses a mat to be laid on the ground or the like. The mat includes a base, a rigid plate laminated on the base, and a cushion layer laminated on the rigid plate. The rigid plate is provided with elongated ribs. The ribs are made of a hard material. This makes it possible to prevent the mat from warping in the longitudinal direction of the ribs.

[0003] JP 2009-275374 A

[0004] However, depending on the material of the ribs, there is a risk that they may deform due to heat, water absorption, etc. In such cases, there is a risk that the rug may warp.

[0005] An object of the present disclosure is to provide a paving material that can effectively suppress warping.

[0006] The paving material disclosed herein comprises a main body having a mating front and back surface, and is used with the back surface facing the ground. The direction perpendicular to the back surface is defined as the thickness direction, and the direction in the thickness direction when looking at the back surface from the front surface is defined as the downward thickness direction. The main body has at least one hollow portion and at least one back recess that opens to the downward thickness direction, and the thickness direction dimension of the internal space of the back recess is greater than 2 mm.

[0007] Fig. 1 is a perspective view of a paving material of a first embodiment. Fig. 2 is a front view of a paving material of a first embodiment. Fig. 3 is a process diagram showing a method of constructing a paving material. Fig. 4 is a schematic view showing a state in which the paving material of the first embodiment is used. Fig. 5 is a front view of a paving material of a second embodiment. Fig. 6 is a front view of a paving material of a third embodiment. Fig. 7 is a front view of a paving material of a fourth embodiment.

[0008] First Embodiment A first embodiment of the present disclosure will now be described with reference to the drawings. As shown in Figures 1 and 2, a paving material 1 includes a main body 10 having a pair of front and back surfaces F1 and F2. The paving material 1 is used with the back surface F2 facing the ground. The front surface F1 and the back surface F2 each have a rectangular planar shape, more specifically, a square planar shape.

[0009] In this specification, the direction perpendicular to the back surface F2 is referred to as the "thickness direction T." Of the directions in the thickness direction T, the direction when looking from the back surface F2 to the front surface F1 is referred to as the "upper thickness direction T1," and the direction in the thickness direction T when looking from the front surface F1 to the back surface F2 is referred to as the "lower thickness direction T2." Of the directions perpendicular to the thickness direction T, one direction is referred to as the "length direction L." The direction perpendicular to the thickness direction T and the length direction L is referred to as the "width direction W." Of the directions in the width direction W, one direction is referred to as the "one width direction side W1," and the other direction is referred to as the "other width direction side W2."

[0010] The main body 10 is formed as a plate overall, for example, a square plate when viewed in the thickness direction T. Each side of the front surface F1 and each side of the back surface F2 extend parallel to either the length direction L or the width direction W. When the paving material 1 is in use, the thickness direction T coincides with the direction perpendicular to the ground. The paving material 1 is formed, for example, as a single piece. The material of the paving material 1 will be described later.

[0011] Of the outer surfaces of the main body 10, the outer surfaces that face each other in the width direction W are referred to as "width-direction side surfaces F3," and the outer surfaces that face each other in the length direction L are referred to as "length-direction side surfaces F4."

[0012] The thickness direction T dimension of the paving material 1 is, for example, approximately 40 mm. The thickness direction T dimension of the paving material 1 is preferably within the range of 30 mm to 60 mm. The length direction L dimension of the paving material 1 is, for example, approximately 300 mm. The length direction L dimension of the paving material 1 is preferably within the range of 100 mm to 2000 mm. The width direction W dimension of the paving material 1 is, for example, approximately 300 mm. The width direction W dimension of the paving material 1 is preferably within the range of 100 mm to 800 mm.

[0013] The main body 10 has at least one hollow portion 11 and at least one back recess 12 that opens to the lower side T2 in the thickness direction. The main body 10 has a hollow structure with the hollow portion 11 provided therein.

[0014] The hollow portion 11 extends in the length direction L. The hollow portion 11 penetrates the main body 10 in the length direction L. The hollow portion 11 has an inner circumferential surface 11b that surrounds the internal space 11a of the hollow portion 11. The internal space 11a of the hollow portion 11 has, for example, a rectangular shape with the width direction W as the longitudinal direction when viewed in the length direction L, more specifically, a rectangular shape with rounded corners. In this case, the inner circumferential surface 12b of the hollow portion 11 has a curved surface portion 12ba. By forming the inner circumferential surface 11b of the hollow portion 11 into a curved surface, stress concentration on the angular portions of the inner circumferential surface 11b can be suppressed.

[0015] The distance between the hollow portion 11 and the front surface F1 and the distance between the hollow portion 11 and the back surface F2 are, for example, the same. The thickness direction T dimension of the internal space 11a of the hollow portion 11 is approximately 1 / 3 of the thickness direction T dimension of the main body portion 10. It is preferable that the thickness direction T dimension of the internal space 11a of the hollow portion 11 is within a range of 1 / 4 to 1 / 2 of the thickness direction T dimension of the main body portion 10. Note that the distance between the hollow portion 11 and the front surface F1 and the distance between the hollow portion 11 and the back surface F2 do not necessarily have to be the same.

[0016] The main body 10 is provided with, for example, a plurality of hollow portions 11; more specifically, four hollow portions 11. The plurality of hollow portions 11 are spaced apart in the width direction W, for example, equally spaced apart in the width direction W. Two of the hollow portions 11 closer to one width direction side W1 and the other two hollow portions 11 closer to the other width direction side W2 are located on either side of the center of the width direction W of the main body 10; more specifically, they are located symmetrically in the width direction W with respect to the center of the width direction W of the main body 10. Note that the plurality of hollow portions 11 need only be spaced apart in the width direction W, and do not necessarily have to be spaced apart equally.

[0017] The backside recess 12 is recessed from the back surface F2. The backside recess 12 has an inner peripheral surface 12b surrounding an internal space 12a of the backside recess 12. The thickness direction T dimension of the internal space 12a of the backside recess 12 is greater than 2 mm, preferably 3 mm to 20 mm, and preferably 4 mm to 15 mm. For example, when the thickness direction T dimension of the main body 10 is 40 mm, the thickness direction T dimension of the internal space 12a of the backside recess 12 is greater than 1 / 15 and less than 1 / 2 of the thickness direction T dimension of the main body 10, and preferably 1 / 10 to 1 / 3 of the thickness direction T dimension of the main body 10. In this case, the thickness direction T dimension of the internal space 12a of the backside recess 12 is, specifically, approximately 1 / 5 of the thickness direction T dimension of the main body 10.

[0018] If water is present on the surface to be paved with the paving material 1 (sometimes simply referred to as the "surface to be paved"), there is a risk that the paving material 1 will absorb the water. However, by providing the backside recess 12 in the main body 10, it is possible to prevent the paving material 1 from coming into contact with water on the surface to be paved. By making the thickness direction T dimension of the internal space 12a of the backside recess 12 greater than 2 mm, it is possible to effectively prevent the paving material 1 from coming into contact with water on the surface to be paved. This makes it possible to effectively prevent the paving material 1 from absorbing water.

[0019] Since the thickness direction T dimension of the internal space 12a of the rear recess 12 is 20 mm or less, the impact resistance of the paving material 1 can be sufficiently ensured.

[0020] Therefore, the durability of the paving material 1 can be sufficiently ensured while the water absorption of the paving material 1 can be suitably suppressed.

[0021] The rear recess 12 has a groove shape extending in the length direction L. The rear recess 12 penetrates the main body 10 in the length direction L.

[0022] If water accumulates around the paving material 1, it is thought that the paving material 1 will be more likely to absorb water. However, by providing the backside recess 12 that penetrates the main body 10, water can be smoothly drained between the paving material 1 and the surface to be paved. This prevents water from accumulating around the paving material 1. This also prevents the paving material 1 from absorbing water.

[0023] The inner space 12a of the rear recess 12 has a shape including an isosceles trapezoid whose width dimension W decreases toward the upper side T1 in the thickness direction when viewed in the length direction L. More specifically, the inner space 12a has a shape including an isosceles trapezoid with rounded corners. In this case, the inner peripheral surface 12b of the rear recess 12 has a curved surface portion 12ba.

[0024] The main body 10 is provided with, for example, a plurality of rear recesses 12, more specifically, two rear recesses 12. The rear recesses 12 are provided at intervals in the width direction W.

[0025] The rear recesses 12 are provided on either side of the center of the width direction W of the main body 10, and more specifically, are provided at positions symmetrical in the width direction W with respect to the center of the width direction W of the main body 10. The rear recesses 12 are spaced apart from the respective ends of the main body 10 in the width direction W.

[0026] The back-side recesses 12 on one widthwise side W1 of each of the hollow portions 11 are located closer to the one widthwise side W1 than the hollow portions 11 on the one widthwise side W1 of each of the hollow portions 11. The back-side recesses 12 on the other widthwise side W2 of each of the hollow portions 11 are located closer to the other widthwise side W2 than the hollow portions 11 on the other widthwise side W2 of each of the hollow portions 11. The hollow portions 11 and the back-side recesses 12 are spaced apart in the width direction W when viewed in the thickness direction T. In other words, the hollow portions 11 and the back-side recesses 12 do not overlap when viewed in the thickness direction T.

[0027] The end of the internal space 12a of the rear recess 12 on the upper side T1 in the thickness direction and the end of the internal space 11a of the hollow portion 11 on the lower side T2 in the thickness direction are, for example, spaced apart in the thickness direction T. However, this is not limited to this, and the end of the internal space 12a of the rear recess 12 on the upper side T1 in the thickness direction and the end of the internal space 11a of the hollow portion 11 on the lower side T2 in the thickness direction may be aligned in the thickness direction T.

[0028] The shortest distance between the rear recess 12 and the hollow portion 11 adjacent to the rear recess 12 is equal to or greater than the shortest distance between the hollow portion 11 and the rear surface F2. In the drawings, the shortest distance between the rear recess 12 and the hollow portion 11 adjacent to the rear recess 12 is indicated as "d1," and the shortest distance between the hollow portion 11 and the rear surface F2 is indicated as "d2."

[0029] In addition, in the hollow portion 11, the curved portion 11ba is provided so as to include the portion of the inner circumferential surface 11b that is closest to the back-side recess 12. The inner circumferential surface 11b of the hollow portion 11 is formed in a curved shape. This makes it easier to increase d1.

[0030] In the rear recess 12, the curved surface portion 12ba is provided so as to include the portion of the inner circumferential surface 12b that is closest to the hollow portion 11. This makes it easier to increase d1.

[0031] Additionally, for example, multiple backside small grooves 13 are provided on the back surface F2 of the main body 10. Each backside small groove 13 has an inner peripheral surface 13b surrounding an internal space 13a of the backside small groove 13. The thickness direction T dimension of the internal space 13a of the backside small groove 13 is, for example, 0.1 mm or more and 2 mm or less, preferably 0.5 mm or more and 2 mm or less. For example, when the thickness direction T dimension of the main body 10 is 40 mm, the thickness direction T dimension of the internal space 13a of the backside small groove 13 is within the range of 1 / 300 to 1 / 20 of the thickness direction T dimension of the main body 10. The thickness direction T dimension of the internal space 13a of the backside small groove 13 is, for example, 1 mm. The backside small groove 13 is groove-shaped and extends in the length direction L. For example, the backside small groove 13 penetrates the main body 10 in the length direction L.

[0032] The rear small groove portion 13 provided on the rear surface F2 of the main body portion 10 can prevent the paving material 1 from shifting horizontally.

[0033] The inner peripheral surface 13b of the back-side small groove portion 13 has, for example, a V-shape that is convex toward the lower side T2 in the thickness direction when viewed in the length direction L. However, the shape of the inner peripheral surface 13b of the back-side small groove portion 13 is not limited to this. The inner peripheral surface 13b of the back-side small groove portion 13 may have a curved surface shape, for example, a U-shape that is convex toward the lower side T2 in the thickness direction when viewed in the length direction L.

[0034] The surface F1 of the main body 10 is provided with, for example, a plurality of front-side small grooves 14. Each front-side small groove 14 has an inner circumferential surface 14b that surrounds an internal space 14a of the front-side small groove 14. The thickness direction T dimension of the internal space 14a of the front-side small groove 14 is, for example, 0.1 mm to 2 mm, preferably 0.5 mm to 2 mm. For example, when the thickness direction T dimension of the main body 10 is 40 mm, the thickness direction T dimension of the internal space 14a of the front-side small groove 14 is within a range of 1 / 300 to 1 / 20 of the thickness direction T dimension of the main body 10. The thickness direction T dimension of the internal space 14a of the front-side small groove 14 is, for example, 1 mm. The width direction W dimension of the open end of the internal space 14a of the front-side small groove 14 is within a range of 1 / 1600 to 1 / 35 of the width direction W dimension of the main body 10. The width W of the opening end of the internal space 14a of the front small groove 14 is, for example, 1.5 mm. The front small groove 14 is groove-shaped and extends in the length direction L. The front small groove 14 penetrates the main body 10 in the length direction L, for example.

[0035] The small grooves 14 on the surface F1 of the main body 10 can prevent pedestrians from slipping. Also, the gloss of the surface F1 can be varied to improve the aesthetic appearance of the paving material 1.

[0036] The inner peripheral surface 14b of the front-side small groove portion 14 has, for example, a V-shape that is convex toward the lower side T2 in the thickness direction when viewed in the length direction L. However, the shape of the inner peripheral surface 14b of the front-side small groove portion 14 is not limited to this. The inner peripheral surface 14b of the front-side small groove portion 14 may have a curved surface shape, for example, a U-shape that is convex toward the lower side T2 in the thickness direction when viewed in the length direction L. Furthermore, the shape of the back-side small groove portion 13 and the shape of the front-side small groove portion 14 may be the same shape or different shapes.

[0037] The main body 10 is provided with at least one (more specifically, two) side recesses 16 that open in a direction perpendicular to the thickness direction T. One side recess 16 is provided on each widthwise side surface F3. Each side recess 16 opens in the width direction W. Each side recess 16 is concave relative to its corresponding widthwise side surface F3. Each side recess 16 has a groove shape extending in the length direction L. Each side recess 16 extends over the entire length of each widthwise side surface F3 in the length direction L. The internal space 16a of each side recess 16 has a rectangular shape with the thickness direction T as the longitudinal direction when viewed in the length direction L.

[0038] The main body 10 has at least one (more specifically, two) side protrusions 18 that are convex in a direction perpendicular to the thickness direction T. One or more (more specifically, one) side protrusions 18 are provided on each longitudinal side surface F4. Each side protrusion 18 is convex in the longitudinal direction L. Each side protrusion 18 is spaced apart from each end of the main body 10 in the thickness direction T. Each side protrusion 18 has a ridge shape extending in the longitudinal direction L. Each side protrusion 18 extends over the entire length of the main body 10 in the longitudinal direction L. When viewed in the longitudinal direction L, each side protrusion 18 has a rectangular shape with the thickness direction T as its longitudinal direction.

[0039] The thickness direction T dimension of the side convex portion 18 is equal to or less than the thickness direction T dimension of the internal space 16a of the side recess 16. In the two paving materials 1, the side convex portion 18 of one paving material 1 can be inserted into the side recess 16 of the other paving material 1.

[0040] Next, the material of the paving material 1 will be described. The paving material 1 contains, for example, a low-melting-point resin, and non-low-melting-point resin particles and cellulose-based material particles dispersed in the low-melting-point resin. Note that a molded body of a composition containing a resin substrate containing a low-melting-point resin, non-low-melting-point resin particles dispersed in the resin substrate, and cellulose-based material particles dispersed in the resin substrate is sometimes referred to as a "resin composition molded body." The paving material 1 is a resin composition molded body.

[0041] The low-melting-point resin is, for example, a resin whose melting point is in the range of 80°C or higher and lower than 190°C. The low-melting-point resin is, for example, a thermoplastic resin. Examples of low-melting-point resins include polystyrene (PS), acrylonitrile-butadiene-styrene resin (ABS), polyethylene (PE), polymethyl methacrylate (PMMA), polycarbonate (PC), polypropylene (PP), polyamide 12 (PA12), and polyacetal (POM).

[0042] The content of the low-melting-point resin, as a content relative to the total amount of the resin composition molded article, is in the range of 12% by mass to 78% by mass, or may be in the range of 12% by mass to 48% by mass, or 14% by mass to 43% by mass, or 17% by mass to 43% by mass.

[0043] The low-melting-point resin may contain at least polyethylene (PE) and polypropylene (PP). The mass ratio of PE to PP (PE / PP) may be, for example, 5.0 or less, or 3.0 or less.

[0044] The non-low melting point resin particles include, for example, at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin. The melting point of the high melting point resin is, for example, 340°C or lower. Examples of high melting point resins include polyethylene terephthalate (PET), polyamide 6 (PA6), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). The thermosetting resin is a resin after curing. Examples of thermosetting resins include polyimide (PI), polyurethane (PU), and phenolic resin (PF). The average major axis of the non-low melting point resin particles is, for example, less than 3 mm.

[0045] The low-melting-point resin and non-low-melting-point resin particles may be derived from waste, which allows for effective use of resources. The low-melting-point resin and non-low-melting-point resin particles may be separated and recovered from waste plastic collected in accordance with the Containers and Packaging Recycling Law, for example.

[0046] Plastic waste can include municipal solid waste, industrial waste, and marine plastic waste. Municipal waste is waste other than industrial waste and marine plastic waste, including household waste discarded from ordinary households. Plastic waste may contain substances other than synthetic resins. The substances other than synthetic resins may be inorganic or organic. Examples of inorganic substances include magnetic substances, non-magnetic metals, glass, pebbles, metals, shells, sand, desiccants such as silica gel, and iron-based oxygen absorbers. Examples of magnetic substances include iron, stainless steel, ferrite, cobalt, and nickel. Examples of non-magnetic metals include aluminum, copper, zinc, and brass. Examples of organic substances include oils and fats, food residues, and surfactants.

[0047] Examples of plastic waste derived from municipal waste include plastics used as product containers and packaging materials. Waste plastic residue is the residue remaining after separating and recovering a portion of the resin contained in waste plastic derived from municipal waste, such as the residue remaining after separating and recovering a portion of the low-melting-point resin. The low-melting-point resin to be separated and recovered may include, for example, at least one of PP, PE, and PS, or may include both PP and PE. Waste plastic residue may be the residue remaining after separating and recovering 5% by mass or more of the low-melting-point resin contained in the waste plastic, or 5% by mass to 95% by mass or less, or 5% by mass to 50% by mass or less, or 5% by mass to 15% by mass or less. The sum of PP and PE may account for 20% by mass or more of the separated and recovered low-melting-point resin, or may be in the range of 50% by mass to 100% by mass or less, or 70% by mass to 100% by mass or less.

[0048] Plastic waste derived from industrial waste is plastic waste generated as a result of business activities. Examples of plastic waste derived from industrial waste include substandard products and surplus production. Plastic waste derived from marine plastic waste is plastic waste that has accumulated in the ocean due to direct disposal of plastic in the ocean or plastic discarded on land that has washed up in rivers and lakes. Plastic waste derived from marine plastic waste includes, for example, plastic discarded in the ocean (plastic pieces, PET bottles, fishing gear), and microplastics that are plastic products that have deteriorated due to the effects of waves and ultraviolet rays and are now 5 mm or smaller in size.

[0049] When the plastic waste is waste plastic residue, the content of low-melting-point resin in the synthetic resin contained in the waste plastic residue may be, for example, 95% by mass or less, or may be, for example, in the range of 25% by mass to 95% by mass or less, or in the range of 35% by mass to 90% by mass or less. The total content of PE, PP, and PS in the synthetic resin contained in the waste plastic residue may be 80% by mass or less, or may be 70% by mass or less. The total content of PE, PP, and PS may be in any of the ranges of 5% by mass to 80% by mass, 25% by mass to 80% by mass, 25% by mass to 75% by mass, or 30% by mass to 70% by mass.

[0050] The form of the plastic waste is not particularly limited, and may be, for example, bale-like or block-like. When the production units (lots) of resin composition molded products are divided according to the type of plastic waste, the plastic waste used in each production unit may be generated at different locations or times. For example, the plastic waste used in each production unit may have a standard deviation of 2% by mass or more in the content of low-melting-point resin, and may be in the range of 2% by mass or more and 23% by mass or less.

[0051] The particle size of the cellulose-based material particles is not particularly limited, but among particles with a major axis of 1.0 mm or more, the content of particles with a major axis of 2.5 mm or more may be 30% by number or less. Furthermore, the content of particles with a major axis of less than 1.5 mm may be 40% by number or more and 60% by number or less. The content of these particles can be determined by observing a cross section of a resin composition molded product using an optical microscope and measuring the particle diameter of the cellulose-based material particles.

[0052] The content of cellulose-based material particles having a major axis of 4.0 mm or more may be 2.0 particles / 100 mm or less, or 1.0 particles / 100 mm or less, as the average content contained in a 10 mm x 10 mm region of the cross section of the resin composition molded product. The average content of cellulose-based material particles can be determined, for example, by dividing the cross section of the resin composition molded product into 10 mm x 10 mm regions and measuring the particle sizes of the cellulose-based material particles present in 1,000 divided regions using an optical microscope.

[0053] The cellulosic material particles include at least wood particles. The cellulosic material particles may include pulp particles as particles other than wood particles. The content of wood particles relative to the cellulosic material particles may be 52% by mass or more, or 82% by mass or more.

[0054] The wood particles are, for example, crushed waste wood. In this case, resources can be effectively utilized. Examples of waste wood that can be used include construction waste, thinned wood, and sawdust. The average major axis of the wood particles is, for example, less than 3 mm.

[0055] The content of the cellulose-based material particles, as a content relative to the total amount of the resin composition molded body, is in the range of 12% by mass to 48% by mass, and may be in the range of 22% by mass to 38% by mass.

[0056] The ratio of the content of the cellulose-based material particles to the content of the low-melting-point resin contained in the resin substrate (content of cellulose-based material particles / content of low-melting-point resin) may be 4.0 or less.

[0057] The content of the cellulosic material particles may vary depending on the size of the cellulosic material particles. For example, in the case of cellulosic material particles that have passed through a sieve with 1 mm openings, the content may be in the range of 12% by mass to 48% by mass.

[0058] The ratio of the content of cellulose-based material particles passing through a sieve with 1 mm mesh size to the content of low-melting-point resin may be within the range of 0.2 to 4.0.

[0059] In the case of cellulose-based material particles that have passed through a sieve with 2 mm openings, the content may be in the range of 12% by mass or more and 38% by mass or less.

[0060] The ratio of the content of cellulose-based material particles passing through a sieve with 2 mm openings to the content of low-melting-point resin may be in the range of 0.05 or more and 2.5 or less.

[0061] In the case of cellulose-based material particles that have passed through a sieve with 3 mm openings, the content may be in the range of 12% by mass or more and 38% by mass or less.

[0062] The ratio of the content of cellulose-based material particles passing through a sieve with 3 mm openings to the content of low-melting-point resin may be in the range of 0.05 to 1.5.

[0063] The particle size of the non-low melting point resin particles is not particularly limited, but among particles with a major axis of 1.0 mm or more, the content of particles with a major axis of 2.5 mm or more may be 30% by number or less, and the content of particles with a major axis of less than 1.5 mm may be 40% by number or more.

[0064] The content of non-low melting point resin particles having a major axis of 4.0 mm or more may be 2.0 particles / 100 mm or less, or 1.0 particles / 100 mm or less, as the average content contained in a 10 mm x 10 mm cross-sectional area of ​​the resin composition molded body.

[0065] The content of the non-low melting point resin particles is in the range of 12% by mass to 78% by mass inclusive, or may be in the range of 17% by mass to 73% by mass inclusive, or in the range of 32% by mass to 58% by mass inclusive, relative to the total amount of the resin composition molded article.

[0066] The content of non-low melting point resin particles and low melting point resin may be, for example, 0.3 or more and less than 10, in terms of the ratio of the content of non-low melting point resin particles to the content of low melting point resin (content of non-low melting point resin particles / content of low melting point resin).

[0067] The paving material 1 may further contain additives such as pigments, compatibilizers for improving the affinity between the low-melting resin particles, non-low-melting resin particles, and wood particles, fillers, lubricants, weathering agents, heat stabilizers, foaming agents, and antistatic agents.

[0068] The content of the additive is, for example, in the range of 4% by mass to 11% by mass relative to the total amount of the resin composition molded article.

[0069] The resin composition molded product may contain inevitable impurities. Inevitable impurities are impurities that are inevitably mixed in raw materials or during the production process. Examples of inevitable impurities include aluminum derived from aluminum-deposited plastics contained in waste plastics used as raw materials for low-melting-point resins and non-low-melting-point resin particles. The aluminum content relative to the total amount of the resin composition molded product may be, for example, less than 2 mass%.

[0070] When the plastic waste is waste plastic residue, the content of non-low melting point resin in the synthetic resin contained in the waste plastic residue may be, for example, 5% by mass or more, may be in the range of 5% by mass or more and 75% by mass or less, or may be in the range of 10% by mass or more and 65% by mass or less.

[0071] Next, a method for manufacturing the paving material 1 will be described.

[0072] The method for manufacturing the paving material 1 includes a resin raw material preparation step, a wood particle preparation step, a mixing step, an extrusion step, and a cutting step.

[0073] First, a resin raw material preparation process is carried out. In the resin raw material preparation process, for example, low-melting point resin and non-low-melting point resin particles are recovered from a plastic raw material. The plastic raw material is, for example, plastic waste. The resin raw material preparation process includes, for example, a crushing process, a magnetic material removal process, a non-magnetic metal removal process, a water washing process, a volume reduction process, and a pulverization process.

[0074] The shredding process is a process in which plastic waste is shredded using a shredder to obtain plastic fragments. The magnetic substance removal process is a process in which magnetic substances contained in plastic fragments are removed and recovered using a magnetic separator. The non-magnetic metal removal process is a process in which non-magnetic metals contained in plastic fragments are removed and recovered using a non-magnetic metal separator. The water washing process is a process in which plastic fragments are crushed into coarse plastic particles using a wet crushing and washer equipped with a crushing function, while deposits adhering to the coarse plastic particles are washed and removed. The deposits include organic matter such as oils and fats, food residue, and surfactants, and inorganic matter such as glass, pebbles, metals, shells, sand, desiccants, and oxygen absorbers. The volume reduction process is a process in which moisture adhering to the coarse plastic particles is removed and the volume of the coarse plastic particles is reduced using a compression volume reduction machine. The crushing process is a process in which the coarse plastic particles are crushed using a crusher to obtain resin composition particles.

[0075] Next, a wood particle preparation step is carried out. In the wood particle preparation step, wood particles are collected from wood, for example, waste wood. The wood particle preparation step includes, for example, a crushing step, a magnetic substance removal step, and a pulverization step.

[0076] The crushing step is a step of crushing wood using a crusher to obtain wood chips. The magnetic substance removal step is a step of removing and recovering magnetic substances contained in the wood chips using a magnetic separator. The pulverization step is a step of crushing the wood chips using a pulverizer to obtain wood particles. The wood chips may be crushed simultaneously with the crushing of the plastic coarse particles using the same device as that used to crush the plastic coarse particles.

[0077] The plastic raw materials and wood used in the resin raw material preparation step and wood particle preparation step are not limited to waste materials, but may also be valuable resources. In the resin raw material preparation step and wood particle preparation step, ready-made resin powder or wood powder may be prepared as low-melting point resin and non-low-melting point resin particles or wood particles.

[0078] Next, a mixing step is carried out. The mixing step is a step of mixing low-melting point resin and non-low-melting point resin particles with wood particles. In the mixing step, the resin particles / resin composition particles and wood particles are put into a mixer. The mixer is, for example, a heater mixer. The resin particles / resin composition particles and wood particles are kneaded while being heated by the mixer. This allows for a mixture in which each raw material is uniformly dispersed (hereinafter sometimes referred to as a "raw material mixture").

[0079] The total content of the low-melting point resin and non-low-melting point resin in the raw material mixture is, for example, within the range of 50 to 90% by mass. The content of wood particles is, for example, within the range of 5 to 40% by mass. The content of additives is, for example, within the range of 5 to 40% by mass. Furthermore, the ratio of the content of the low-melting point resin to the content of the non-low-melting point resin in the resin composition powder mixture is, for example, within the range of 1 / 3 to 5 by mass.

[0080] Next, the extrusion process is carried out. The extrusion process is a process in which the raw material mixture is extruded using an extrusion molding machine. The raw material mixture is extruded from the nozzle of the extrusion molding machine while being molded into the desired shape. The opening shape of the nozzle is the same as the shape of the paving material 1 when viewed in the length direction L. Therefore, the molded body that emerges from the nozzle has the back side recess 12, front side recess 15, side side recess 16, etc. formed in the desired shapes. Each side of the main body 10 and the open end of each back side recess 12 are, for example, rounded.

[0081] The back-side recess 12, the front-side recess 15, and the side-side recess 16 are each provided penetrating the main body 10 in the length direction L. With this configuration, the back-side recess 12, the front-side recess 15, and the side-side recess 16 can be easily formed in the main body 10 by extrusion molding. Furthermore, while attempting to increase the thickness direction T dimension of the internal space 12a of the back-side recess 12 makes the paving material 1 more susceptible to damage during molding, forming the back-side recess 12 by extrusion molding makes it easier to increase the thickness direction T dimension of the internal space 12a of the back-side recess 12 while suppressing damage to the paving material 1.

[0082] The molding temperature of the extruder varies depending on factors such as the type and content of the low-melting-point resin contained in the raw material mixture, but is preferably, for example, 80°C or higher. This allows the low-melting-point resin particles to melt. A molded product can be obtained in which non-low-melting-point resin particles and wood particles are dispersed in the low-melting-point resin. Because wood particles decompose and gasify at temperatures above 190°C, which can cause bubbles to form in the molded product of the raw material mixture, the molding temperature of the extruder is preferably below 190°C.

[0083] Next, a cutting process is carried out. The molded body formed in the extrusion process is cut, for example, by a cutting device. First, the molded body is cut in a direction perpendicular to the direction in which the molded body is extruded (specifically, a direction parallel to the thickness direction T and the width direction W). This allows the molded body to have the desired length direction L dimension. Next, horizontal (specifically, length direction L) cuts are made on the cut surface of the molded body at positions spaced a predetermined distance from the front surface F1 and a predetermined distance from the back surface F2. Next, vertical (specifically, parallel to the thickness direction T and the width direction W) cuts are made on the front surface F1 and the back surface F2 of the molded body, respectively, so as to connect to the horizontal cuts. As a result, each end of the molded body in the thickness direction T and length direction L is cut off as a small rectangular prism-shaped piece, and side convex portions 18 are formed on the main body portion 10.

[0084] The shape of each part of the main body 10 may be formed by grinding the molded body after the extrusion process. Also, the main body 10 may be subjected to appropriate chamfering.

[0085] The method for producing the paving material 1 (resin composition molded article) of this embodiment may also include an analysis step.

[0086] The analysis step is carried out before the mixing step. The analysis step is a step of analyzing the composition of the resin composition powder. The composition of the resin composition powder can be determined by the ratio of the content of the low-melting point resin to the content of the non-low-melting point resin in the resin composition powder.

[0087] The content of low-melting point resin and the content of non-low-melting point resin in the resin composition powder can be analyzed by, for example, separating the low-melting point resin and the non-low-melting point resin by utilizing the difference in specific gravity between them, and measuring the content of each separated resin.

[0088] More specifically, for example, a resin composition powder is immersed in a heavy liquid as a sample powder. Next, the amount of floating matter rising to the surface of the heavy liquid and the amount of sediment that sinks are measured. The floating matter is scooped out of the heavy liquid. The sediment is recovered by filtering the heavy liquid after all of the floating matter has been scooped out. The recovered floating matter and sediment are washed with water, dried, and the amounts of floating matter and sediment are measured. The amount of floating matter is then taken as the content of the low-melting-point resin, and the amount of sediment is taken as the content of the non-low-melting-point resin. This allows the contents of the low-melting-point resin and non-low-melting-point resin to be measured quickly and accurately.

[0089] The specific gravity of the heavy liquid can be, for example, 1.08 to 1.13. This allows for more accurate measurement of the content of low-melting-point resin and non-low-melting-point resin. The heavy liquid may be, for example, an organic solvent such as ethylene glycol, or an aqueous solution of an inorganic salt such as a sodium chloride solution. To prevent the sample powder from floating up due to its buoyancy, the particle size of the sample powder may be 3 mm or less. Furthermore, if air bubbles are attached to the sample powder, resin powder that would otherwise settle in the heavy liquid may float up. By stirring under appropriate conditions or adding a surfactant or the like to the heavy liquid, air bubble attachment can be suppressed, improving analytical accuracy.

[0090] When the analysis step is performed, the mixing ratio of the resin composition powder to the melting point resin-containing powder and / or the non-low melting point resin-containing powder may be adjusted in the mixing step based on the ratio of the low melting point resin content to the non-low melting point resin content of the resin composition powder obtained in the analysis step.

[0091] The analysis process determines the ratio of low-melting-point resin to non-low-melting-point resin in the resin composition powder, and the mixing process adjusts the content of the low-melting-point resin to the non-low-melting-point resin to an appropriate component ratio, thereby maintaining a stable viscosity of the molten raw material mixture. This improves moldability during extrusion. This allows plastic waste to be used in shapes that are difficult to mold, further expanding the scope of effective use of plastic waste.

[0092] In this way, the paving material 1 can be obtained.

[0093] Next, a method for applying the paving material 1 will be described with reference to FIGS.

[0094] As shown in Figure 3, the construction method for paving material 1 includes a step S1 of placing roadbed material 51 on the ground G, a step S2 of placing base material 52 on roadbed material 51, a step S3 of placing paving material 1 on base material 52, and a joint filling step S4.

[0095] First, step S1 is performed to place a roadbed material 51 on the ground G. As shown in FIG. 4, the roadbed material 51 is placed on the ground G to form a layer of the roadbed material 51 (hereinafter, sometimes referred to as the "roadbed"). The roadbed material 51 is, for example, crusher run. Next, compaction of the roadbed is performed to compact the roadbed and smooth the surface of the roadbed. It is preferable that the thickness of the roadbed be 100 mm or more.

[0096] Next, step S2 is performed to place the base material 52 on the roadbed material 51. The base material 52 is placed on the roadbed material 51 to form a layer of the base material 52. The base material 52 is, for example, basa mortar. Next, the surface of the layer of the base material 52 is smoothed with a leveling board or a trowel.

[0097] Next, step S3 is performed to place the paving material 1 on the base material 52. The paving material 1 is placed on the base material 52 with the back surface F2 facing the base material 52. Adjacent paving materials 1 may be spaced apart or may be abutting. Multiple paving materials 1 are arranged, for example, with the length directions L of adjacent paving materials 1 intersecting (more specifically, perpendicular to) each other. Of the adjacent paving materials 1, the side convex portion 18 of one paving material 1 is inserted into the side concave portion 16 of the other paving material 1. This prevents the paving materials 1 from warping or rattling.

[0098] Next, the joint filling process S4 is carried out. Joint material 53 is placed between adjacent paving materials 1. If a structure such as a curb B is present on the side of the paving material 1, joint material 53 is placed between the paving material 1 and the curb B. The joint material 53 is, for example, joint sand or modified silicone. This can suppress rattling of the paving material 1. Note that the joint sand is not shown in Figure 4.

[0099] This completes the construction of the paving material 1.

[0100] The paving material 1 of this embodiment has the following effects.

[0101] According to this embodiment, the paving material 1 includes a main body 10 having a pair of front and back surfaces F1 and F2. The main body 10 is used with the back surface F2 facing the ground. The main body 10 includes at least one hollow portion 11 and at least one back recess 12 that opens to the lower side T2 in the thickness direction. The dimension of the internal space 12a of the back recess 12 in the thickness direction T is greater than 2 mm.

[0102] With this configuration, when the paving material 1 expands due to water absorption or the like, the paving material 1 can expand toward the internal space 11a of the hollow portion 11. This can prevent changes in the external shape of the paving material 1, and therefore, can effectively prevent warping of the paving material 1.

[0103] Furthermore, by providing the rear recess 12 on the rear surface F2 of the main body 10, contact between the main body 10 and water can be suppressed, for example, when water is present on the surface to be paved. The dimension of the internal space 12a of the rear recess 12 in the thickness direction T is greater than 2 mm, which effectively suppresses contact between the main body and water. This prevents the paving material 1 from absorbing water, thereby suppressing its expansion due to water absorption. This effectively suppresses warping of the paving material 1.

[0104] The dimension of the internal space 12a of the rear recess 12 in the thickness direction T is 20 mm or less, which ensures sufficient impact resistance of the paving material 1.

[0105] According to this embodiment, the main body 10 has a plurality of hollow portions 11 spaced apart in a direction perpendicular to the thickness direction T (specifically, in the width direction W).

[0106] According to this configuration, the hollow portions 11 can suppress expansion of the paving material 1 at various locations of the paving material 1. This makes it possible to more effectively suppress warping of the paving material 1.

[0107] According to this embodiment, the main body 10 has a plurality of rear recesses 12 spaced apart in a direction perpendicular to the thickness direction T (specifically, in the width direction W).

[0108] This configuration makes it possible to suppress moisture absorption in various parts of the paving material 1. Therefore, it is possible to suppress the water absorption and expansion of the paving material 1 in various parts of the paving material 1. As a result, it is possible to more effectively suppress warping of the paving material 1.

[0109] According to this embodiment, the hollow portion 11 and the back side recess 12 (more specifically, the back side recess 12) are spaced apart in a direction perpendicular to the thickness direction T (more specifically, the width direction W) when viewed in the thickness direction T.

[0110] When the main body 10 has a hollow portion 11 and a rear recess 12, it is expected that a portion of the main body 10 will be formed thin. In this case, there is a concern that the impact resistance of the paving material 1 will be reduced. With this configuration, it is possible to prevent the portion of the main body 10 between the hollow portion 11 and the rear recess 12 from becoming so thin that it affects impact resistance, thereby improving the impact resistance of the paving material 1.

[0111] According to this embodiment, the shortest distance between the rear recess 12 and the hollow portion 11 adjacent to the rear recess 12 is equal to or greater than the shortest distance between the hollow portion 11 and the rear surface F2.

[0112] With this configuration, the portion of the main body 10 between the hollow portion 11 and the rear recess 12 can be prevented from becoming thin, thereby improving the impact resistance of the paving material 1.

[0113] According to this embodiment, the main body 10 is provided with at least one front recess 15 that opens to the upper side T1 in the thickness direction.

[0114] According to this configuration, since the main body 10 has a plurality of front side recesses 15, the direction of reflection of light hitting the main body 10 can be changed, thereby giving the paving material 1 a unique luster.

[0115] The rear recess 12 has an inner circumferential surface 12 b with a curved surface portion 12 ba that is curved, and the curved surface portion 12 ba is provided so as to include the portion of the inner circumferential surface 12 b that is closest to the hollow portion 11 .

[0116] This configuration makes it possible to prevent the portion between the hollow portion 11 and the rear recess 12 from becoming thin, compared to when the portion of the inner circumferential surface 12b closest to the hollow portion 11 is a corner. This makes it easier to ensure the durability of the paving material 1.

[0117] According to this embodiment, the paving material 1 comprises wood particles.

[0118] This configuration makes it possible to obtain a paving material 1 that has a texture similar to that of wood, thereby improving the design of the paving material 1.

[0119] Furthermore, wood particles have a high affinity for water. Therefore, if wood particles are included in the paving material 1, there is a risk that the paving material 1 will be prone to absorbing water and expanding. However, according to the above embodiment, the hollow portion 11 and the back recess 12 can suppress the absorbing water expansion of the paving material 1 and the warping of the paving material 1 caused by the absorbing water expansion of the paving material 1. This allows the design of the paving material 1 to be improved while suppressing warping of the paving material 1.

[0120] According to this embodiment, the paving material 1 contains a low-melting resin, and non-low-melting resin particles and wood particles dispersed in the low-melting resin. The low-melting resin has a melting point in the range of 80°C or higher and lower than 190°C. The non-low-melting resin particles contain at least one of a high-melting resin having a melting point of 190°C or higher and a thermosetting resin having a melting point of 190°C or higher.

[0121] With this configuration, the wood particles are dispersed in the low-melting resin. This prevents the wood particles from coming into contact with water, thereby suppressing water absorption by the wood particles. Non-low-melting resin particles are dispersed in the low-melting resin. This prevents the water absorption of the paving material 1 from increasing, while increasing the strength of the paving material 1.

[0122] When dispersing wood particles and non-low-melting resin particles in a low-melting resin, the mixture of wood particles, non-low-melting resin particles, and low-melting resin is heated to melt the low-melting resin. However, the wood particles may gasify at high temperatures. This can cause bubbles to form in the molded product, which can detract from the aesthetic appearance of the molded product.

[0123] However, with this configuration, the melting point of the low-melting-point resin is in the range of 80°C or higher and lower than 190°C. Therefore, the low-melting-point resin can be melted at a temperature in the range of 80°C or higher and lower than 190°C. By setting the temperature of the raw material mixture in the range of 80°C or higher and lower than 190°C, gasification of the wood particles can be suppressed. Therefore, the wood particles and non-low-melting-point resin particles can be dispersed in the low-melting-point resin while suppressing the generation of bubbles in the molded product of the raw material mixture.

[0124] Furthermore, with this configuration, the weight of the paving material 1 can be reduced, which improves workability when installing the paving material 1, etc.

[0125] Second Embodiment Next, a paving material 1 according to a second embodiment of the present disclosure will be described with reference to Fig. 5. The following description will focus on differences from the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0126] In the second embodiment, the main body 10 is provided with at least one front-side recess 15, e.g., three front-side recesses 15, that open to the upper side T1 in the thickness direction and extend in the length direction L. The front-side recess 15 is recessed relative to the surface F1. The front-side recess 15 has an inner circumferential surface 15b that surrounds an internal space 15a of the front-side recess 15. The thickness direction T dimension of the internal space 15a of the front-side recess 15 is greater than 2 mm, preferably greater than 2 mm and less than 10 mm, and preferably greater than 2 mm and less than 7 mm. Furthermore, for example, if the thickness direction T dimension of the main body 10 is 40 mm, the thickness direction T dimension of the internal space 15a of the front-side recess 15 is preferably within a range of 1 / 15 to 1 / 6 of the thickness direction T dimension of the main body 10.

[0127] Since the front side recess 15 extends in the length direction L, the paving material 1 can be cut straight or a plurality of paving materials 1 can be cut to uniform dimensions by cutting the paving material 1 along the front side recess 15.

[0128] The thickness direction T dimension of the internal space 15a of the front recess 15 is greater than 2 mm, which makes it easy to cut the paving material 1. In addition, when cutting the paving material 1, it is easier to determine the position of the cutting tool.

[0129] By making the thickness direction T dimension of the internal space 15a of the front side recess 15 smaller than 10 mm, the durability of the paving material 1 can be sufficiently ensured.

[0130] Therefore, the durability of the paving material 1 can be sufficiently ensured while the paving material 1 can be easily cut.

[0131] The front recess 15 preferably penetrates the main body 10 in the length direction L.

[0132] In this case, water on the surface F1 of the paving material 1 can be discharged to the outside of the surface F1 through the front-side recess 15, thereby preventing water from accumulating on the surface F1 of the paving material 1. Furthermore, the front-side recess 15 can be easily formed in the main body 10 by extrusion molding.

[0133] The thickness T dimension of the internal space 15a of the front recess 15 is preferably in the range of more than 2 mm and not more than 5 mm.

[0134] In this case, it is more preferable that the paving material 1 can be easily cut while the durability of the paving material 1 is sufficiently ensured.

[0135] The front recess 15 has a curved inner circumferential surface 15b, which is U-shaped when viewed in the length direction L, for example.

[0136] The curved inner peripheral surface 15b of the front recess 15 reduces stress concentration on the angular portions of the inner peripheral surface 15b of the front recess 15. This prevents a decrease in the durability of the paving material 1.

[0137] Each of the front-side recesses 15 is provided at a position where it overlaps with a portion of the main body 10 between adjacent hollow portions 11 in the width direction W. In other words, none of the front-side recesses 15 overlaps with any of the hollow portions 11 in the thickness direction T.

[0138] This configuration makes it easier to ensure the distance between the front recess 15 and the hollow portion 11, thereby preventing cracks from occurring between the front recess 15 and the hollow portion 11. This prevents a decrease in the impact resistance of the paving material 1.

[0139] Furthermore, if the hollow portion 11 is separated when the paving material 1 is cut along the front-side recess 15, a portion where the main body 10 is thin will be formed at the end of the paving material 1 after cutting. In this case, the end of the paving material 1 will be more likely to chip, which could reduce the impact resistance of the paving material 1. With this configuration, it is possible to prevent the hollow portion 11 from being separated when the paving material 1 is cut along the front-side recess 15. This makes it possible to prevent a reduction in the impact resistance of the paving material 1.

[0140] In the second embodiment, one or more (more specifically, one) side recess 16 is provided on each of the pair of widthwise side surfaces F3.

[0141] When a joint material 53 is placed between adjacent paving pieces 1, the joint material 53 can penetrate into the internal space 16a of the side recess 16. Therefore, when the paving piece 1 tries to warp in the width direction W, the end of the paving piece 1 in the width direction W gets caught by the joint material 53. This makes it possible to suppress warping of the paving piece 1 in the width direction W. Furthermore, by providing a side recess 16 on both of the paired width direction side surfaces F3, warping of the paving piece 1 in the width direction W can be more effectively suppressed.

[0142] In the second embodiment, the main body 10 is not provided with the back-side small groove 13 or the front-side small groove 14. However, this is not limited to this, and the main body 10 may be provided with the front-side small groove 14 in the second embodiment. Furthermore, in the first embodiment, the main body 10 may be provided with the front-side recess 15. The main body 10 may be provided with both the front-side small groove 14 and the front-side recess 15, or with only one of them, or with neither.

[0143] Third Embodiment Next, a paving material 1 according to a third embodiment of the present disclosure will be described with reference to Fig. 6. The following description will focus on differences from the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0144] As shown in FIG. 6, in the third embodiment, the main body 10 is not provided with a rear recess 12 .

[0145] With this configuration, the impact resistance of the paving material 1 can be improved compared to a configuration in which the main body 10 is provided with a back side recess 12.

[0146] In the third embodiment, the main body 10 is provided with at least one (more specifically, one) hollow portion 11 extending in the length direction L. Even if the main body 10 does not have a rear recess 12, the hollow portion 11 provided in the main body 10 can suppress warping of the paving material 1. However, the configurations of the first and second embodiments are preferred in that they can more effectively suppress warping of the paving material 1.

[0147] In the third embodiment, one hollow portion 11 is provided in the main body portion 10. The center portion of the hollow portion 11 in the width direction W and the center portion of the main body portion 10 in the width direction W overlap with each other in the thickness direction T, for example.

[0148] In this way, it is not necessary to provide a plurality of hollow portions 11. By providing at least one hollow portion 11 in the main body portion 10, warping of the paving material 1 can be suppressed.

[0149] When the main body 10 does not have the back-side recess 12, the paving material 1 is likely to be heavy compared to a configuration in which the main body 10 has the back-side recess 12. This raises concerns about inconveniences such as a decrease in the workability of the paving material 1.

[0150] Therefore, the paving material 1 of the third embodiment comprises a low-melting point resin and non-low-melting point resin particles and wood particles dispersed in the low-melting point resin, and it is preferable that the melting point of the low-melting point resin is in the range of 80°C or higher and lower than 190°C, and that the non-low-melting point resin particles comprise at least one of a high-melting point resin having a melting point of 190°C or higher and a thermosetting resin having a melting point of 190°C or higher.

[0151] According to this configuration, the paving material 1 can be formed from a relatively lightweight material, which prevents the paving material 1 from becoming too heavy.

[0152] Fourth Embodiment Next, a paving material 1 according to a fourth embodiment of the present disclosure will be described with reference to Fig. 7. The following description will focus on differences from the first embodiment, and the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

[0153] As shown in FIG. 7, in the fourth embodiment, the main body 10 does not have a hollow portion 11 .

[0154] With this configuration, the impact resistance of the paving material 1 can be improved compared to a configuration in which a hollow portion 11 is provided in the main body portion 10.

[0155] In the fourth embodiment, the main body 10 is provided with at least one (more specifically, two) back recesses 12 that extend in the length direction L and open to the lower side T2 in the thickness direction. Even if the main body 10 does not have a hollow portion 11, the back recesses 12 provided in the main body 10 can suppress warping of the paving material 1. However, the configurations of the first and second embodiments are preferred in that they can more effectively suppress warping of the paving material 1.

[0156] If the main body 10 does not have a hollow portion 11, the paving material 1 is likely to be heavier than if the main body 10 has a hollow portion 11.

[0157] Therefore, similar to the third embodiment, the paving material 1 of the fourth embodiment contains a low-melting resin and non-low-melting resin particles and wood particles dispersed in the low-melting resin, the melting point of the low-melting resin being in the range of 80°C or higher and lower than 190°C, and the non-low-melting resin particles preferably containing at least one of a high-melting resin having a melting point of 190°C or higher and a thermosetting resin having a melting point of 190°C or higher. This configuration prevents the paving material 1 from becoming too heavy.

[0158] Although one embodiment of the paving material of the present disclosure has been described above, the configuration of the paving material of the present disclosure can be modified as appropriate.

[0159] For example, the back-side recess 12, the front-side recess 15, and the side-side recess 16 may be formed by recessing the outer surface of the main body 10, or may be formed by being sandwiched between two protrusions protruding from the main body 10. The side-side protrusion 18 may be a protrusion protruding from the main body 10, or may be formed by being sandwiched between two recesses formed by recessing the main body 10.

[0160] In each of the above embodiments, the main body 10 has a generally rectangular plate shape overall, but there are no particular limitations on the shape of the main body 10. Furthermore, there are no particular limitations on the shape of the main body 10 in a plan view in the thickness direction T, and it may be, for example, a square or a rectangle.

[0161] In the above embodiments, the internal space 12a of the rear recess 12 has an isosceles trapezoidal shape in which the width W dimension decreases toward the top of the thickness direction when viewed in the length direction L, but the shape of the internal space 12a of the rear recess 12 is not particularly limited. However, in order to effectively prevent water from seeping into the main body 10, it is preferable that the thickness T dimension of the internal space 12a of the rear recess 12 be greater than 2 mm. In order to effectively ensure the strength of the paving material 1, it is preferable that the thickness T dimension of the internal space 12a of the rear recess 12 be 20 mm or less.

[0162] In the first, second, and fourth embodiments, each rear recess 12 is spaced apart from each end of the main body 10 in the width direction W, but this is not limiting. The rear recess 12 may be recessed from the rear surface F2 and from the width direction side surface F3.

[0163] In the first, second, and fourth embodiments, the rear recess 12 has a groove shape extending in the longitudinal direction L, but the shape of the rear recess 12 is not limited to this. The rear recess 12 may be formed, for example, in the shape of a circular hole. This configuration can also suppress water absorption by the paving material 1. In this case, however, the rear recess 12 is formed, for example, by grinding after the extrusion process. The configurations of the first, second, and fourth embodiments are preferred because the rear recess 12 can be easily formed by extrusion molding.

[0164] In the first, second, and fourth embodiments, the main body 10 is provided with two rear recesses 12, but the number of rear recesses 12 provided in the main body 10 is not particularly limited. The rear recesses 12 do not necessarily need to penetrate the main body 10 in the longitudinal direction L. However, the configurations of the above embodiments are preferred in that they can more effectively suppress moisture absorption by the paving material 1 and that the rear recesses 12 can be easily formed in the main body 10 by extrusion molding.

[0165] In the second to fourth embodiments, the shape of the inner peripheral surface 15ba of the front-side recess 15 is U-shaped, convex toward the lower side T2 in the thickness direction, as viewed in the length direction L, but the shape of the inner peripheral surface 15b of the front-side recess 15 is not particularly limited. However, in terms of being able to suppress stress concentration on the inner peripheral surface of the front-side recess 15, it is preferable that the inner peripheral surface 15b of the front-side recess 15 be curved.

[0166] In the second to fourth embodiments, the main body 10 is provided with a front-side recess 15, but the front-side recess 15 is not an essential component. The number of front-side recesses 15 provided in the main body 10 is not particularly limited. The number of front-side recesses 15 provided in the main body 10 may be one, two, or four or more. Furthermore, the position at which the front-side recess 15 is provided in the main body 10 is not limited to that in the second to fourth embodiments.

[0167] The shape of the inner peripheral surface 15b of the front recess 15 is not limited to those of the second to fourth embodiments. The inner peripheral surface 15b of the front recess 15 does not have to be curved, and may, for example, be V-shaped, convex toward the lower side T2 in the thickness direction when viewed in the length direction L. In this case, it is easier to determine the position of the cutting tool when cutting the paving material 1.

[0168] In each of the above embodiments, the main body 10 is provided with a side recess 16, but the side recess 16 is not an essential component. By providing the hollow portion 11 and the back recess 12 in the main body 10, warping of the paving material 1 can be suppressed even if the main body 10 does not have a side recess 16. Furthermore, the number of side recesses 16 provided in the main body 10 is not particularly limited.

[0169] The side recess 16 may be provided on only one of the pair of width-direction side surfaces F3 of the main body 10. In this case, at least one (more specifically, one) side protrusion 18 that is convex in the width direction W may be provided on one of the pair of width-direction side surfaces F3 of the main body 10. In this case, for example, between adjacent paving materials 1, the side protrusion 18 of one paving material 1 can be inserted into the side recess 16 of the other paving material 1.

[0170] In this case, by inserting the side convex portion 18 of one of the adjacent paving materials 1 into the side concave portion 16 of the other paving material 1, it is possible to suppress warping of the paving materials 1. It is also possible to suppress misalignment of the paving materials 1.

[0171] The shape of the side recess 16 as viewed in the length direction L and the shape of the side protrusion 18 as viewed in the length direction L are not particularly limited. The side protrusion 18 of one paving material 1 does not necessarily have to be insertable into the side recess 16 of another paving material 1.

[0172] In the above-described embodiments, the hollow portions 11 and the rear recesses 12 are provided in positions in the main body 10 where they do not overlap when viewed in the thickness direction T, but this is not limited to this. However, the configurations of the above-described embodiments are preferable in that they can suitably ensure the strength of the paving material 1.

[0173] In the above embodiments, the paving material 1 includes a low-melting resin and non-low-melting resin particles and wood particles dispersed in the low-melting resin, the melting point of the low-melting resin being in the range of 80°C or higher but lower than 190°C, and the non-low-melting resin particles including at least one of a high-melting resin having a melting point of 190°C or higher and a thermosetting resin having a melting point of 190°C or higher, but the material of the paving material 1 is not particularly limited. For example, the paving material 1 does not need to include wood particles or various resin materials.

[0174] The method of applying the paving material 1 is not limited to the methods described in the above embodiments, but can be modified as appropriate.

[0175] The present disclosure will be described in more detail below based on examples. The present disclosure is not limited to these examples. In these examples, wastes 1 to 4 were used as plastic waste, with the low-melting-point resin and non-low-melting-point resin contents shown in Table 1 below. Wastes 1 to 4 are waste plastic residues derived from general waste that remain after the low-melting-point resin is separated and recovered from general waste. The ratio of low-melting-point resin content to non-low-melting-point resin content of wastes 1 to 4 is lower than that of general waste. This makes material recycling difficult. Material recycling is particularly difficult for wastes with a low-melting-point resin content / non-low-melting-point resin content ratio of less than 1.00. Recycled resin is low-melting-point resin separated and recovered from general waste. Recycled resin has a high low-melting-point resin content / non-low-melting-point resin content ratio and is used for material recycling.

[0176]

[0177] Example 1 (Production of Resin Composition Powder) Waste 1 was placed in a crusher and crushed. The crushed material obtained was subjected to a high-magnetic pulley-type magnetic separator with a magnetic force of 2000 Gauss on the belt surface to remove iron-containing materials. The crushed material from which the iron-containing materials had been removed was then crushed in a uniaxial coarse crusher until it passed through a 50 mm mesh sieve, yielding plastic fragments (crushing step). The magnetic materials contained in the resulting plastic fragments were removed and recovered using a hanging magnetic separator and a pulley-type magnetic separator (magnetic material removal process). Next, non-magnetic metals contained in the plastic fragments were removed and recovered using a non-magnetic metal separator (non-magnetic metal removal process). Next, the plastic fragments were washed and removed while being crushed using a wet crusher and washer until they passed through a 12 mm mesh sieve, yielding coarse plastic particles (water washing process). Next, the coarse plastic particles obtained in the wet grinding and washing machine were compressed and dehydrated using a volume reduction and compression dehydrator to reduce the volume, resulting in a coarse plastic powder with a moisture content of 0.5% by mass (volume reduction process). Finally, the coarse plastic powder was pulverized using a cutter mill-type pulverizer until it passed through a sieve with 2 mm openings (pulverization process). In this way, a resin composition powder was obtained. The presence or absence of the magnetic substance removal process, non-magnetic metal removal process, water washing process, and volume reduction process, and the opening diameter of the sieve used in the pulverization process are shown in Table 2 below.

[0178] (Production of wood flour) Waste wood was fed into a crusher and crushed using a uniaxial coarse crusher until it passed through a sieve with 50 mm openings, obtaining wood chips (crushing process). Magnetic materials contained in the obtained wood chips were removed and recovered using a hanging magnetic separator and a pulley magnetic separator (magnetic material removal process). Next, the wood chips were crushed using a cutter mill-type crusher until they passed through a sieve with 1 mm openings (crushing process). In this way, wood powder was obtained. The opening diameters of the sieves used in the crushing process are shown in Table 2 below.

[0179] (Method for manufacturing resin composition molded body) 60 parts by mass of resin composition powder, 30 parts by mass of wood powder, and 10 parts by mass of additives (a mixture containing a pigment, a compatibilizer, an inorganic filler, a lubricant, and a weathering material) were mixed at 150 ° C. using a heater mixer. The resulting mixture was molded using an extruder with a rectangular cross-sectional mold 30 mm thick and 300 mm wide to obtain a plate-shaped resin composition molded body. During extrusion molding, a hollow portion and a backside recess were formed in the resin composition molded body. The composition of the obtained resin composition molded body is shown in Table 3 below.

[0180] The resulting molded resin composition articles were evaluated for bending strength, water resistance, and mildew resistance by the following methods, and the results are shown in Table 3 below.

[0181] (Bending strength) Bending strength (three-point bending) is measured using a full-scale test specimen in accordance with Method B specified in JIS A 5741:2016 (recycled wood-plastic composite material). Bending strength of 20 MPa or more is rated as "S", 15 MPa or more but less than 20 MPa is rated as "A", 10 MPa or more but less than 15 MPa is rated as "B", and less than 10 MPa is rated as "C".

[0182] (Water Resistance) The sample is immersed in warm water adjusted to 60°C. The sample is taken out of the warm water every day and the thickness of the sample is measured. The change rate of thickness compared to the thickness of the sample on the previous day is calculated using the following formula (1): Change rate of sample thickness (%) = (sample thickness - sample thickness on the previous day) / sample thickness on the previous day x 100 (1)

[0183] When the change in thickness of the sample becomes 0.5% or less, it is assumed that the expansion rate of the sample's thickness due to water absorption has reached equilibrium, and the equilibrium expansion rate of the sample's thickness is calculated using the following formula (2). The sample thickness was determined as the average of the thicknesses at five locations: the center of the plane and the areas near each of the four corners. Equilibrium expansion rate (%) = {(Tf - Ti) / Ti} × 100 (2) In formula (2), Tf (unit: mm) is the thickness of the resin composition molded article when the change in thickness becomes 0.5% or less, and Ti (unit: mm) is the thickness of the resin composition molded article before immersion in warm water. Water resistance is evaluated as "S" when the equilibrium expansion rate is 5% or less, "A" when it is 10% or less, "B" when it is more than 10% and 20% or less, and "C" when it is more than 20%.

[0184] (Mold resistance) According to Method A specified in Appendix A (Testing of plastic products) of JIS Z 2911:2018 (Mold resistance test method), the area of ​​the sample on which mycelia have grown after two weeks is measured. Mold resistance is rated as "A" if the growth area is less than 25%, "B" if it is 25% or more but less than 50%, and "C" if it is 50% or more.

[0185] [Examples 2 to 16] Resin composition powders and wood flour were produced in the same manner as in Example 1, except that the conditions for producing the resin composition powder and wood flour were changed as shown in Table 2, and resin composition molded articles were produced using the obtained resin composition powders and wood flour. Table 3 shows the bending strength, water resistance, and mold resistance of the obtained resin composition molded articles.

[0186]

[0187]

[0188] The results shown in Table 3 demonstrate that resin composition powders obtained in Examples 1 to 16, which were subjected to the magnetic material removal treatment, non-magnetic metal removal treatment, water washing treatment, and volume reduction treatment, can be used to obtain resin composition molded articles with excellent bending strength, water resistance, and mold resistance. In particular, the resin composition molded articles obtained in Examples 2 and 11, in which the sieve mesh size of the pulverizer used in the production of the resin composition powder was 1 mm, and in Examples 8 and 16, in which the sieve mesh size was 500 μm, exhibited improved bending strength. This is because the use of resin composition powder that passed through a 1 mm or 500 μm sieve resulted in the dispersion of fine, non-low-melting-point resin particles in the resin composition molded article in an island-like pattern. These results demonstrate that, from the perspective of bending strength of the resin composition molded article, it is preferable for the resin composition powder to be fine, i.e., to be finely ground. On the other hand, finely grinding the resin composition powder tends to reduce the processing capacity and long-term stability of the pulverizer, and it is therefore preferable to use a sieve mesh size of 1 mm or larger in the case of a cutter mill-type pulverizer. Furthermore, the resin composition molded bodies obtained in Examples 4 and 12, in which the sieve used in the mill to produce the wood flour had a mesh size of 500 μm, exhibited improved water resistance. This is because the use of fine wood flour that passed through a sieve with a mesh size of 500 μm as the wood flour, which is a water absorption factor in the water resistance test, allows the wood flour to be efficiently mixed and dispersed in the low-melting-point resin, thereby suppressing changes in water absorption in the resin composition molded body. The results of Examples 1 to 16 confirmed that waste plastic residues that were previously used for thermal recycling can be used for material recycling by performing the magnetic material removal process, non-magnetic metal removal process, water washing process, and volume reduction process according to the present disclosure.

[0189] [Aspect 1] A paving material comprising a main body having a mating front and back surfaces, the back surface facing the ground when used, the thickness direction being a direction perpendicular to the back surface, and the thickness direction being defined as a direction in which the back surface is viewed from the front surface to the bottom surface. The main body has at least one hollow portion and at least one back-side recess that opens downward in the thickness direction, and the thickness direction dimension of the internal space of the back-side recess is greater than 2 mm. [Aspect 2] The paving material of Aspect 1, wherein the hollow portion and the back-side recess are spaced apart in a direction perpendicular to the thickness direction when viewed in the thickness direction. [Aspect 3] The paving material of Aspects 1 or 2, wherein the main body has a plurality of hollow portions spaced apart in a direction perpendicular to the thickness direction. [Aspect 4] The paving material of any one of Aspects 1 to 3, wherein the main body has a plurality of back-side recesses spaced apart in a direction perpendicular to the thickness direction. [Aspect 5] The paving material according to Aspect 4, wherein the shortest distance between the rear-side recess and the hollow portion adjacent to the rear-side recess is equal to or greater than the shortest distance between the hollow portion and the rear surface. [Aspect 6] The paving material according to any one of Aspects 1 to 5, wherein the main body portion has at least one front-side recess that opens upward in the thickness direction and extends in the length direction, and the dimension of the internal space of the front-side recess in the thickness direction is greater than 2 mm. [Aspect 7] The paving material according to Aspect 6, wherein the front-side recess has a curved inner circumferential surface. [Aspect 8] The paving material according to Aspects 6 or 7, wherein the hollow portion and the front-side recess are spaced apart in a direction perpendicular to the thickness direction. [Aspect 9] The paving material according to Aspects 1 to 9, wherein the rear-side recess has an inner circumferential surface that has a curved portion, and the curved portion is arranged to include the portion of the inner circumferential surface that is closest to the hollow portion. [Aspect 10] The paving material according to any one of Aspects 1 to 9, wherein the paving material comprises wood particles. [Aspect 11] The paving material according to Aspect 10, comprising a low melting point resin, and non-low melting point resin particles and the wood particles dispersed in the low melting point resin, wherein the melting point of the low melting point resin is in the range of 80°C or higher and lower than 190°C, and the non-low melting point resin particles comprise at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin having a melting point of 190°C or higher.

[0190] 1: paving material, F1: surface, F2: back surface, 11: hollow portion, 12: back side recess, 15: front side recess, 15b: inner surface, 15ba: curved surface portion.

Claims

1. A paving material comprising a main body having a mating front and back surface, the back surface facing the ground when used, the direction perpendicular to the back surface being defined as the thickness direction, and the direction in the thickness direction when looking at the back surface from the front surface being defined as the bottom side in the thickness direction, the main body having at least one hollow portion and at least one back recess that opens to the bottom side in the thickness direction, and the dimension in the thickness direction of the internal space of the back recess being greater than 2 mm.

2. The paving material according to claim 1, wherein the hollow portion and the rear recess are spaced apart in a direction perpendicular to the thickness direction when viewed in the thickness direction.

3. A paving material as described in claim 1 or 2, wherein the main body portion has a plurality of hollow portions spaced apart in a direction perpendicular to the thickness direction.

4. A paving material as described in any one of claims 1 to 3, wherein the main body portion has a plurality of rear recesses spaced apart in a direction perpendicular to the thickness direction.

5. A paving material as described in claim 4, wherein the shortest distance between the rear recess and the hollow portion adjacent to the rear recess is equal to or greater than the shortest distance between the hollow portion and the rear surface.

6. A paving material as described in any one of claims 1 to 5, wherein the main body portion is provided with at least one front-side recess that opens upward in the thickness direction and extends in the length direction, and the dimension of the internal space of the front-side recess in the thickness direction is greater than 2 mm.

7. The paving material according to claim 6, wherein the front recess has a curved inner peripheral surface.

8. A paving material according to claim 6 or 7, wherein the hollow portion and the front-side recess are spaced apart in a direction perpendicular to the thickness direction.

9. A paving material as described in any one of claims 1 to 8, wherein the rear recess has an inner surface with a curved portion that forms a curved shape, and the curved portion is arranged to include the portion of the inner surface that is closest to the hollow portion.

10. The paving material of any one of claims 1 to 9, wherein the paving material comprises wood particles.

11. A paving material as described in claim 10, comprising: a low melting point resin; non-low melting point resin particles and wood particles dispersed in the low melting point resin; the melting point of the low melting point resin is in the range of 80°C or higher but lower than 190°C; and the non-low melting point resin particles comprise at least one of a high melting point resin having a melting point of 190°C or higher and a thermosetting resin having a melting point of 190°C or higher.

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