Method for manufacturing non-pneumatic tires

Abstract

To provide a method for manufacturing a non-pneumatic tire and a non-pneumatic tire which can secure adhesive force between a support structure and a tread without using a support structure containing a resin having a specific chemical structure or specific physical properties.SOLUTION: There is provided a method for manufacturing a non-pneumatic tire having a support structure 10 containing a resin, and a tread which is positioned outside the support structure 10 in a tire radial direction X and extends in a tire circumferential direction. The method for manufacturing the non-pneumatic tire includes a step of sequentially applying a first adhesive 2 and a second adhesive 3 to a surface outside the support structure 10 in a tire radial direction X, and vulcanizing and bonding the support structure 10 to which the first adhesive 2 and the second adhesive 3 are sequentially applied, and a rubber composition 4 for the tread. The first adhesive 2 has higher compatibility with the resin contained in the support structure 10 than that of the second adhesive 3, and the second adhesive 3 is a vulcanization adhesive.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a non-pneumatic tire and to a non-pneumatic tire. [Background technology]

[0002] Conventionally, non-pneumatic tires have been known that include a support structure that supports a load from a vehicle and a tread that is located radially outward of the support structure and extends along the tire circumferential direction.

[0003] In non-pneumatic tires, if the tread separates from the support structure, it will cause problems in the running of the vehicle, so it is desirable to ensure adhesive strength between the support structure and the tread.

[0004] Therefore, Patent Document 1 describes the production of a support structure by curing a polyurethane composition containing an isocyanate-terminated prepolymer having a double bond in the main chain, an organic sulfide, and dimethylthiotoluenediamine.

[0005] Furthermore, Patent Document 2 describes that the storage modulus at 150° C. of the resin contained in the connecting structure that connects the inner annular portion and the outer annular portion of the support structure is set to 8 MPa or more. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5175587 [Patent Document 2] Japanese Patent Application Publication No. 2019-218002 Summary of the Invention [Problem to be solved by the invention]

[0007] However, Patent Documents 1 and 2 require the use of a support structure containing a resin having a specific chemical structure or specific physical properties.

[0008] An object of the present invention is to provide a method for manufacturing a non-pneumatic tire that can ensure adhesive strength between a support structure and a tread without using a support structure that includes a resin having a specific chemical structure or specific physical properties, and a non-pneumatic tire. [Means for solving the problem]

[0009] One aspect of the present invention is a method for manufacturing a non-pneumatic tire comprising a support structure containing a resin and a tread located radially outward of the support structure and extending circumferentially along the tire, the method comprising the steps of sequentially applying a first adhesive and a second adhesive to the radially outer surface of the support structure, and vulcanizing and bonding the support structure to which the first adhesive and the second adhesive have been sequentially applied and a rubber composition for the tread, wherein the first adhesive has a higher affinity for the resin than the second adhesive, and the second adhesive is a vulcanizing adhesive.

[0010] The resin may be a urethane resin, the first adhesive may be an epoxy resin-based adhesive or a urethane resin-based adhesive, and the second adhesive may include a halogenated polymer.

[0011] The support structure may have an arithmetic mean roughness Ra of an outer surface in the tire radial direction of the support structure of 2.0 μm or more and 18.0 μm or less.

[0012] In the method for manufacturing a non-pneumatic tire, the second adhesive may have an applied film thickness of 1.0 μm or more and 23.0 μm or less.

[0013] The pressure applied when vulcanizing and bonding the support structure and the rubber composition for a tread may be 0.6 MPa or more.

[0014] Another aspect of the present invention is a non-pneumatic tire comprising a support structure containing a resin, and a tread located radially outward of the support structure and extending circumferentially along the tire, the tire being manufactured by sequentially applying a first adhesive and a second adhesive to the radially outer surface of the support structure, and then vulcanizing and bonding the support structure and a rubber composition for the tread, wherein the first adhesive has a higher affinity for the resin than the second adhesive, and the second adhesive is a vulcanizing adhesive. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a method for manufacturing a non-pneumatic tire and a non-pneumatic tire that can ensure adhesive strength between a support structure and a tread without using a support structure that includes a resin having a specific chemical structure or specific physical properties. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a side view showing a non-pneumatic tire according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view showing an example of a method for manufacturing the non-pneumatic tire of FIG. 1. FIG. [Figure 3] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Figure 4] FIG. 4 is a partial perspective view of the non-pneumatic tire, as seen obliquely from the portion shown in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] The method for manufacturing a non-pneumatic tire of this embodiment is a method for manufacturing a non-pneumatic tire having a support structure containing resin and a tread located radially outward of the support structure and extending circumferentially along the tire.

[0019] Fig. 1 shows a non-pneumatic tire of this embodiment. The non-pneumatic tire 1 includes a support structure 10 and a tread 50. The support structure 10 contains resin and supports a load from a vehicle. The tread 50 is located outward of the support structure 10 in the tire radial direction X and extends along the tire circumferential direction C. Details of the structure of the non-pneumatic tire 1 will be described later.

[0020] 2 shows an example of a method for manufacturing the non-pneumatic tire 1. When manufacturing the non-pneumatic tire 1, first, a first adhesive 2 and a second adhesive 3 are applied in sequence to the outer surface of the support structure 10 in the tire radial direction X.

[0021] The thickness of the applied film of the first adhesive 2 is not particularly limited, but is, for example, 10 μm or more and 30 μm or less.

[0022] The coating thickness of the second adhesive 3 is preferably 1.0 μm or more and 23.0 μm or less, and more preferably 5.0 μm or more and 20.0 μm or less. When the coating thickness of the second adhesive 3 is 1.0 μm or more and 23.0 μm or less, the adhesive strength between the support structure 10 and the tread 50 is improved.

[0023] If necessary, the first adhesive 2 and the second adhesive 3 may be dried. The drying conditions are not particularly limited, but may be, for example, at a temperature of 50°C or higher and 80°C or lower for 5 minutes or longer and 10 minutes or shorter.

[0024] At this time, after applying the first adhesive 2 and after applying the second adhesive 3, the first adhesive 2 and the second adhesive 3 may be dried, respectively, or after applying the first adhesive 2 and the second adhesive 3, the first adhesive 2 and the second adhesive 3 may be dried.

[0025] Next, the tread rubber composition 4 is attached to the surface of the support structure 10 to which the first adhesive 2 and the second adhesive 3 have been applied in sequence, and then the support structure 10 and the tread rubber composition 4 are vulcanized and bonded together by applying heat and pressure using a vulcanizing device.

[0026] The pressure applied when vulcanizing and bonding the support structure 10 and the rubber composition for tread 4 is preferably 0.6 MPa or more, and more preferably 0.8 MPa or more. When the pressure applied when vulcanizing and bonding the support structure 10 and the rubber composition for tread 4 is 0.6 MPa or more, the adhesive strength between the support structure 10 and the tread 50 is improved.

[0027] Here, the first adhesive 2 has a higher affinity for the resin contained in the support structure 10 than the second adhesive 3, and the second adhesive 3 is a vulcanization adhesive. This results in good compatibility between the resin contained in the support structure 10 and the first adhesive 2, and good compatibility between the first adhesive 2 and the second adhesive 3, and as a result, it is possible to ensure adhesive strength between the support structure 10 and the tread 50 without using a support structure that includes a resin with a specific chemical structure or specific physical properties. In contrast, if the first adhesive 2 is not applied, compatibility between the support structure 10 and the second adhesive 3 will be poor, and as a result, it will be necessary to use a support structure that includes a resin with a specific chemical structure or specific physical properties.

[0028] The material forming the outer surface of the support structure 10 in the tire radial direction X is not particularly limited, but examples thereof include thermoplastic elastomers, crosslinked rubbers, other resins, and the like.

[0029] Here, when the resin constituting the outer surface of the support structure 10 in the tire radial direction X is a urethane resin, the first adhesive 2 can be an epoxy resin adhesive or a urethane resin adhesive, and the second adhesive 3 can be a vulcanization adhesive containing a halogenated polymer. In this case, the second adhesive 3 may further contain a metal oxide (acid acceptor) as necessary.

[0030] Here, the epoxy resin adhesive and the urethane resin adhesive are adhesives containing epoxy resin and urethane resin as main components, respectively.

[0031] The urethane resin may be a known urethane resin used in a support structure. The epoxy resin adhesive or urethane resin adhesive may be a known epoxy resin adhesive or urethane resin adhesive. The halogenated polymer and metal oxide (acid acceptor) may be known halogenated polymers and metal oxides (acid acceptors) used in vulcanization adhesives.

[0032] The first adhesive 2 may be a primer.

[0033] The rubber composition 4 for tread is not particularly limited, but for example, contains natural rubber and carbon black, and may further contain sulfur, silica, etc. Here, the rubber composition 4 for tread may contain synthetic rubber such as polyisoprene rubber, styrene butadiene rubber, etc. together with the natural rubber or instead of the natural rubber.

[0034] The rubber composition 4 for tread may be either an unvulcanized rubber composition or a vulcanized rubber composition.

[0035] The vulcanization temperature is not particularly limited, but is, for example, 140°C or higher and 180°C or lower.

[0036] The arithmetic mean roughness Ra of the outer surface of the support structure 10 in the tire radial direction X is preferably 2.0 μm or more and 18.0 μm or less, and more preferably 5.0 μm or more and 18.0 μm or less. When the arithmetic mean roughness Ra of the outer surface of the support structure 10 in the tire radial direction X is 2.0 μm or more and 18.0 μm or less, the adhesive strength between the support structure 10 and the tread 50 is improved.

[0037] The method for adjusting the surface roughness of the outer surface of the support structure 10 in the tire radial direction X is not particularly limited, but examples thereof include buffing. In this case, it is preferable to degrease and clean the surface of the support structure 10 on the buffed side.

[0038] The structure of the non-pneumatic tire 1 (see FIG. 1) will be described in detail below. FIG. 1 is a side view of the non-pneumatic tire 1 of this embodiment, viewed from the side in a direction parallel to the tire rotation axis (tire meridian), i.e., in a direction along the front-to-back direction of the paper in FIG. 1. The non-pneumatic tire 1 shown in FIG. 1 is in an unloaded state. FIG. 3 is a cross-sectional view taken along line II-II in FIG. 1. FIG. 4 is a partial perspective view of the non-pneumatic tire 1, as viewed obliquely from the portion shown in FIG. 3.

[0039] In Fig. 1 and Fig. 4, arrow C indicates the tire circumferential direction. In Fig. 1, Fig. 3, and Fig. 4, arrow X indicates the tire radial direction. In Fig. 3 and Fig. 4, arrow Y indicates the tire width direction. In Fig. 1, the tire width direction Y is the front-to-back direction of the page. In Fig. 3, symbol E is the tire equatorial plane. In Fig. 3, the tire circumferential direction C is the front-to-back direction of the page.

[0040] The tire circumferential direction C is a direction around the tire rotational axis and is the same direction as the rotational direction of the non-pneumatic tire 1. The tire radial direction X is a direction perpendicular to the tire rotational axis. The tire width direction Y is a direction parallel to the tire rotational axis. In FIGS. 3 and 4, one side of the tire width direction Y is indicated as Y1, and the other side of the tire width direction Y is indicated as Y2. The tire equatorial plane E shown in FIG. 3 is a plane perpendicular to the tire rotational axis and located at the center of the tire width direction Y.

[0041] The non-pneumatic tire 1 of this embodiment includes an inner annular portion 20, an outer annular portion 30, a support structure 10 having a plurality of spokes 40, and a tread 50. Therefore, the outer surface of the support structure 10 in the tire radial direction X is the outer surface of the outer annular portion 30 in the tire radial direction X.

[0042] In the following description, the thickness of the inner annular portion 20 and the outer annular portion 30 refers to the dimension in the tire radial direction X. The width of the inner annular portion 20 and the outer annular portion 30 refers to the dimension in the tire width direction Y shown in FIG.

[0043] The inner annular portion 20 is an annular portion along the tire circumferential direction C that constitutes the inner circumferential portion of the non-pneumatic tire 1. The thickness and width of the inner annular portion 20 are set to be constant to improve uniformity. A tire wheel (not shown) is placed in the space on the inner circumferential side of the inner annular portion 20. The inner circumferential portion of the inner annular portion 20 is fitted onto the outer circumferential portion of the rim of the tire wheel. The inner annular portion 20 is fitted onto the rim, and the non-pneumatic tire 1 is then fitted onto the tire wheel. The inner circumferential surface of the inner annular portion 20 may be provided with a fitting portion consisting of a protrusion, a groove, etc. for fitting with the rim.

[0044] The inner annular portion 20 can be made of, for example, a resin material having elasticity, but the material is not limited to resin.

[0045] The inner annular portion 20 transmits the rotation of the tire wheel to the spokes 40 and the outer annular portion 30. The thickness of the inner annular portion 20 is determined from the viewpoint of achieving light weight and durability while fulfilling the function of sufficiently transmitting rotational force to the spokes 40. The thickness of the inner annular portion 20 is not particularly limited, but is preferably 2% to 7% of the tire cross-sectional height H shown in FIG. 3, and more preferably 3% to 6%.

[0046] The inner diameter of the inner annular portion 20 is determined depending on the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the use of the vehicle, etc. For example, when assuming a replacement for a general pneumatic tire, the inner diameter of the inner annular portion 20 may be, for example, a dimension of 250 mm or more and 500 mm or less, but is not limited to this.

[0047] The width of the inner annular portion 20 is determined appropriately depending on the use of the vehicle on which the non-pneumatic tire 1 is mounted, the length of the axle, etc. For example, when assuming a replacement for a general pneumatic tire, the width of the inner annular portion 20 may be, but is not limited to, a dimension of 100 mm or more and 300 mm or less.

[0048] The outer annular portion 30 is an annular portion along the tire circumferential direction C that constitutes the outer periphery of the non-pneumatic tire 1. The outer annular portion 30 is disposed on the outer circumferential side of the inner annular portion 20 and concentric with the inner annular portion 20. The thickness and width of the outer annular portion 30 are set to be constant to improve uniformity.

[0049] The outer annular portion 30 transmits the rotation of the inner annular portion 20 and the spokes 40 to the road surface via the tread 50. The thickness of the outer annular portion 30 is determined from the viewpoint of achieving light weight and durability while also fulfilling the function of sufficiently transmitting rotational force from the spokes 40 to the road surface. The thickness of the outer annular portion 30 is not particularly limited, but is preferably, for example, 2% to 7% of the tire cross-sectional height H shown in FIG. 3, and more preferably 2% to 5%.

[0050] The inner diameter of the outer annular portion 30 is determined appropriately depending on the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the use of the vehicle, etc. For example, when assuming a replacement for a general pneumatic tire, the inner diameter of the outer annular portion 30 may be, but is not limited to, a dimension of 420 mm or more and 750 mm or less.

[0051] The width of the outer annular portion 30 is determined appropriately depending on the application of the vehicle on which the non-pneumatic tire 1 is mounted, etc. For example, when assuming a replacement for a general pneumatic tire, the width of the outer annular portion 30 may be, but is not limited to, a dimension of 100 mm or more and 300 mm or less.

[0052] The plurality of spokes 40 connect the inner annular portion 20 and the outer annular portion 30. The inner annular portion 20 and the outer annular portion 30, connected by the plurality of spokes 40, are arranged concentrically with each other. The plurality of spokes 40 are arranged independently along the tire circumferential direction C. As shown in FIG. 1 , when the non-pneumatic tire 1 is in an unloaded state, the plurality of spokes 40 extend linearly in the radial direction substantially parallel to the tire radial direction X in a side view.

[0053] As shown in Figures 3 and 4, the multiple spokes 40 of this embodiment include multiple first spokes 41 and multiple second spokes 42. The extension direction of both the first spokes 41 and the second spokes 42 is not parallel to the tire radial direction X when viewed in a direction along the tire circumferential direction C. The first spokes 41 are inclined toward one side in the tire axial direction, i.e., the tire width direction Y. The second spokes 42 are inclined toward the opposite side to the first spokes 41. The first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction C.

[0054] 3 and 4, the first spokes 41 extend at an angle from the Y1 side, which is one side in the tire width direction Y of the outer annular portion 30, toward the Y2 side, which is the other side in the tire width direction Y of the inner annular portion 20. The second spokes 42 extend at an angle from the Y2 side, which is the other side in the tire width direction Y of the outer annular portion 30, toward the Y1 side, which is one side in the tire width direction Y of the inner annular portion 20.

[0055] The inclination angles of the first spokes 41 and the second spokes 42 are the same. Therefore, the first spokes 41 and the second spokes 42 that are adjacent in the tire circumferential direction C are arranged in a substantially X-shape when viewed from a direction along the tire circumferential direction C. As shown in FIG. 3 , the first spokes 41 and the second spokes 42 are inclined at an angle θ with respect to the tire width direction Y, and the angle θ is preferably, for example, 15° or more and 50° or less.

[0056] 3, when viewed in a direction along the tire circumferential direction C, the first spokes 41 and the second spokes 42 each have the same shape and are symmetrical with respect to the tire equatorial plane E. Therefore, hereinafter, when there is no need to distinguish between the first spokes 41 and the second spokes 42 and they can be described together, the first spokes 41 and the second spokes 42 will be collectively referred to as spokes 40.

[0057] The spokes 40 are plate-shaped and extend obliquely at the angle θ from the inner annular portion 20 toward the outer annular portion 30 as described above. As shown in FIG. 4 , the thickness t of the spokes 40 along the tire circumferential direction is smaller than the width w, and the direction of the thickness t is along the tire circumferential direction C. That is, the spokes 40 are formed in a plate shape extending in a plane of the tire radial direction X and the tire width direction Y. Note that the width w here refers to the dimension in a direction perpendicular to the oblique direction in which the spokes 40 extend when viewed from a direction along the tire circumferential direction C, as also shown in FIG. 3 . In this embodiment, all of the spokes 40 have the same thickness t. All of the spokes 40 also have the same width w.

[0058] Because the spokes 40 are long and plate-shaped, the durability of the spokes 40 can be improved by widening the plate width w even if the plate thickness t is thin. Furthermore, by thinning the plate thickness t and increasing the number of spokes 40, the distance between adjacent spokes 40 in the tire circumferential direction C can be reduced while maintaining the rigidity of the entire non-pneumatic tire 1. This distributes the ground contact pressure when the tire rolls through the spokes 40, thereby reducing the ground contact pressure.

[0059] Although the spokes 40 in this embodiment are parallel to the tire radial direction X in a side view, the spokes 40 may be disposed obliquely with respect to the tire radial direction X so as to intersect with the tire radial direction X in a side view.

[0060] 3 and 4 , the first spoke 41 has a first inner connection portion 411 connected to the tire width direction Y2 side of the inner annular portion 20, and a first outer connection portion 412 connected to the tire width direction Y1 side of the outer annular portion 30. The second spoke 42 has a second inner connection portion 421 connected to the tire width direction Y1 side of the inner annular portion 20, and a second outer connection portion 422 connected to the tire width direction Y2 side of the outer annular portion 30. The first outer connection portion 412 and the second outer connection portion 422 are each an example of a connection portion of the spoke 40 connected to the outer annular portion 30 in this embodiment.

[0061] 3 , the first inner connection portion 411 of the first spoke 41 has a shape that widens in the tire width direction Y as it approaches the inner annular portion 20. A side surface 411a on the tire width direction Y2 side of the first inner connection portion 411 extends while gently curving to an end portion 20b on the tire width direction Y2 side of the inner annular portion 20. A side surface 411b on the tire width direction Y1 side of the first inner connection portion 411 extends while curving toward the tire width direction Y1 side to the position of the tire equatorial plane E of the inner annular portion 20.

[0062] The first outer connection portion 412 of the first spoke 41 has a shape similar to that of the first inner connection portion 411, and has a shape that widens in the tire width direction as it approaches the outer annular portion 30. A side surface 412a on the tire width direction Y1 side of the first outer connection portion 412 extends in a gently curved manner to an end portion 30a of the outer annular portion 30 on the tire width direction Y1 side. A side surface 412b on the tire width direction Y2 side of the first outer connection portion 412 extends in a curved manner toward the tire width direction Y2 to the position of the tire equatorial plane E of the outer annular portion 30.

[0063] The first inner connecting portion 411 is provided in a half region on the tire width direction Y2 side of the inner annular portion 20. The first outer connecting portion 412 is provided in a half region on the tire width direction Y1 side of the outer annular portion 30.

[0064] 3, the second inner connection portion 421 of the second spoke 42 has a shape that widens in the tire width direction Y as it approaches the inner annular portion 20. A side surface 421a on the tire width direction Y1 side of the second inner connection portion 421 extends in a gently curved manner to an end portion 20a of the inner annular portion 20 on the tire width direction Y1 side. A side surface 421b on the tire width direction Y2 side of the second inner connection portion 421 extends in a curved manner toward the tire width direction Y2 to the position of the tire equatorial plane E of the inner annular portion 20.

[0065] The second outer connection portion 422 of the second spoke 42 has a shape similar to that of the second inner connection portion 421, and has a shape that widens in the tire width direction as it approaches the outer annular portion 30. A side surface 422a on the tire width direction Y2 side of the second outer connection portion 422 extends in a gently curved manner to an end portion 30b of the outer annular portion 30 on the tire width direction Y2 side. A side surface 422b on the tire width direction Y1 side of the second outer connection portion 422 extends in a curved manner toward the tire width direction Y1 side to the position of the tire equatorial plane E of the outer annular portion 30.

[0066] The second inner connecting portion 421 is provided in a half region on the tire width direction Y1 side of the inner annular portion 20. The second outer connecting portion 422 is provided in a half region on the tire width direction Y2 side of the outer annular portion 30.

[0067] As described above, in this embodiment, all of the spokes 40 have the same thickness t. The dimension of the thickness t is not particularly limited, but is preferably 1 mm or more and 30 mm or less, and more preferably 5 mm or more and 25 mm or less, so that the spokes 40 can fully receive the rotational force from the inner annular portion 20 and the outer annular portion 30 and can be appropriately flexibly deformed when subjected to a load.

[0068] As described above, all spokes 40 in this embodiment have the same width w. The width w of the spokes 40 is not particularly limited, but is preferably 5 mm to 25 mm, more preferably 10 mm to 20 mm, so as to be able to adequately withstand rotational forces from the inner annular portion 20 and the outer annular portion 30 while also being able to flex appropriately when subjected to a load. Furthermore, the width w is preferably 110% or more of the thickness t, more preferably 115% or more, so as to be able to distribute ground pressure while improving durability.

[0069] The number of spokes 40 is preferably 80 to 300, and more preferably 100 to 200, from the viewpoint of being able to adequately support the load from the vehicle while being lightweight and achieving both improved power transmission and durability.

[0070] The dimension of the spoke 40 in the tire radial direction X may be, but is not limited to, 26.8 mm or more and 357.5 mm or less.

[0071] The spokes 40 can be made of any of the elastic materials listed below. First, in terms of the properties of the elastic material, from the viewpoint of providing adequate rigidity while ensuring sufficient durability, the Young's modulus calculated from the tensile stress at 10% elongation in a tensile test conducted in accordance with JIS K7312:1996 is preferably 50 MPa or more and 120 MPa or less, and more preferably 70 MPa or more and 105 MPa or less.

[0072] If the Young's modulus of the spokes 40 is less than 50 MPa, sufficient rigidity cannot be obtained, and there is a possibility that adjacent spokes 40 in the tire circumferential direction C may come into contact with each other. On the other hand, if the Young's modulus of the spokes 40 is more than 120 MPa, the rigidity becomes excessively high, resulting in a deterioration in ride comfort.

[0073] The elastic material used as the base material of the spokes 40 may be a thermoplastic elastomer, a crosslinked rubber, or other resin.

[0074] Examples of thermoplastic elastomers include polyester elastomers, polyolefin elastomers, polyamide elastomers, polystyrene elastomers, polyvinyl chloride elastomers, and polyurethane elastomers.

[0075] The rubber material constituting the crosslinked rubber can be either natural rubber or synthetic rubber. Examples of synthetic rubber include styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IIR), nitrile rubber (NBR), hydrogenated nitrile rubber (hydrogenated NBR), chloroprene rubber (CR), ethylene propylene rubber (EPDM), fluororubber, silicone rubber, acrylic rubber, and urethane rubber. Two or more of these rubber materials may be used in combination as needed.

[0076] Other resins include thermoplastic resins and thermosetting resins. Thermoplastic resins include polyethylene resins, polystyrene resins, polyvinyl chloride resins, etc. Thermosetting resins include epoxy resins, phenolic resins, polyurethane resins, silicone resins, polyimide resins, melamine resins, etc.

[0077] Of the above elastic materials, urethane resin is preferably used for the spokes 40 from the viewpoints of moldability, processability, and cost. However, foamed materials can also be used as the elastic material. That is, foamed materials made from the above thermoplastic elastomers, crosslinked rubber, and other resins can be used.

[0078] The elastic material used as the base material of the spokes 40 may be reinforced with reinforcing fibers. Examples of reinforcing fibers include long fibers, short fibers, woven fabrics, and nonwoven fabrics. Examples of reinforcing fibers include rayon cords, polyamide cords such as nylon-6,6, polyester cords such as polyethylene terephthalate, aramid cords, glass fiber cords, carbon fibers, and steel cords.

[0079] The reinforcement of the elastic material is not limited to reinforcement with reinforcing fibers. For example, reinforcement may be performed by adding granular fillers. Examples of the granular fillers that can be added include carbon black, ceramics such as silica and alumina, and other inorganic fillers.

[0080] Incidentally, it is preferable that the inner annular portion 20 and the outer annular portion 30 are formed from the same resin material as the spokes 40. In this case, the inner annular portion 20, the outer annular portion 30 and the spokes 40 can be integrally molded, for example, by a cast molding method.

[0081] The tread 50 is provided on the outer peripheral surface of the outer annular portion 30 and constitutes the outermost peripheral portion of the non-pneumatic tire 1. As described above, the tread 50 is formed by vulcanization bonding the support structure 10 and the tread rubber composition 4 together. The tread 50 has a tread surface 51 on its outer peripheral surface that comes into contact with the road surface. The tread surface 51 of the tread 50 is provided with a tread pattern formed of a plurality of grooves and land portions, similar to conventional pneumatic tires.

[0082] The tread 50 may be configured by laminating a plurality of vulcanized rubber layers having different components and properties (for example, two or three layers).

[0083] The non-pneumatic tire 1 of the present embodiment may further include a reinforcing layer (not shown). The reinforcing layer may be embedded in the outer annular portion 30. Alternatively, the reinforcing layer may be provided between the outer annular portion 30 and the tread 50. The reinforcing layer is a cylindrical layer extending along the tire circumferential direction C.

[0084] The reinforcing layer is arranged evenly around the entire circumference of the tire to suppress the occurrence of buckling, in which the outer annular portion 30 bends in the tire radial direction X at the center in the tire width direction Y. The reinforcing layer is configured, for example, by arranging steel cords so that they are generally parallel to the tire width direction Y. The reinforcing layer may be a cylindrical metal ring, a high-modulus resin ring, or the like. For example, the reinforcing layer may be a ring made of fiber-reinforced plastic (FRP), such as carbon fiber-reinforced plastic (CFRP) or glass fiber-reinforced plastic (GFRP).

[0085] By providing the reinforcing layer, the rigidity of the non-pneumatic tire 1 is ensured, and the contact of the tread 50 with the road surface is improved.

[0086] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments may be modified as appropriate within the scope of the spirit of the present invention. [Example]

[0087] Examples of the present invention will be described below, but the present invention is not limited to these examples. Since it is difficult to directly measure the adhesive strength between the support structure and the tread using a non-pneumatic tire, the adhesive strength was measured using a test piece simulating a non-pneumatic tire.

[0088] [Example 1] A 100 mm long adhesive area from one end of a 100 mm wide, 200 mm long, and 2.0 mm thick urethane resin sheet was buffed using a sanding belt with a grit size of #80 and a belt sander until the arithmetic mean roughness Ra was 10.2 μm. The adhesive area was then air-blown and degreased with ethanol. Next, an epoxy resin adhesive, Chemlok® 210 (manufactured by LOAD Co., Ltd.), was applied to the adhesive area using a brush, and the adhesive was then dried at 80°C for 10 minutes. Next, a vulcanization adhesive, Chemlok 6108S (manufactured by LOAD Co., Ltd.), containing a halogenated polymer and a metal oxide (acid acceptor), was applied to the adhesive area using a brush, and the adhesive was then dried at 80°C for 10 minutes. An unvulcanized rubber composition was then applied to the adhesive area, and the adhesive was then vulcanized and bonded under conditions of a pressure of 1 MPa, a heating temperature of 140°C, and a heating and pressing time of 36 minutes. Next, a test piece was obtained by cutting it into a piece 25 mm wide and 150 mm long.

[0089] [Comparative Example 1] A test piece was obtained in the same manner as in Example 1, except that the first adhesive was not used.

[0090] Comparative Example 2 A test piece was obtained in the same manner as in Example 1, except that a phenolic resin adhesive, Chemlok 205 (manufactured by LOAD), was used as the first adhesive.

[0091] Comparative Example 3 A test piece was obtained in the same manner as in Example 1, except that a phenolic resin adhesive Chemlok 218E (manufactured by LOAD) was used as the first adhesive.

[0092] [Arithmetic mean roughness Ra of the adhesive area] The arithmetic mean roughness Ra of the adhesive area was measured using a contact type surface roughness meter.

[0093] [Coating film thickness of first adhesive and second adhesive] The dry weight of the applied adhesive was divided by the dry specific gravity and the applied area to calculate the applied film thickness of the first adhesive and the second adhesive.

[0094] [T-type peel test] A T-peel test was carried out at room temperature with reference to JIS K6854-3:1999, and the average peel strength of the test pieces was measured.

[0095] Table 1 shows the preparation conditions of the test specimens and the measurement results of the average peel force. [Table 1]

[0096] Table 1 shows that the test piece of Example 1 had a high average peel strength. In contrast, the test piece of Comparative Example 1 had a low average peel strength because the first adhesive was not applied. Furthermore, the test pieces of Comparative Examples 2 and 3 used a phenolic resin adhesive as the first adhesive, so the affinity of the first adhesive to the urethane resin sheet was lower than the affinity of the second adhesive to the urethane resin sheet, resulting in a low average peel strength. [Explanation of symbols]

[0097] 1 Non-pneumatic tires 1A Precursor to non-pneumatic tires 2. First Adhesive 3 Second Adhesive 4. Rubber composition for tread 10 Support structure 20 Inner annular portion 20a, 20b end 30 Outer annular part 30a, 30b end 40 spokes 41 First Spoke 42 Second Spoke 411 First inner connection 411a, 411b side 412 first outer connection 412a, 412b side 421 Second inner connection 421a, 421b side 422 Second outer connection 422a, 422b side 50 tread 51 tread 60 Vulcanization equipment 61 Lower mold 62 Upper mold 63, 64 segments 63a, 64a Molding surface 65, 66 Packing C Circumferential direction of tire E Tire equatorial plane O axis center X radial direction of tire Y Tire width direction

Claims

[Claim 1] A method for manufacturing a non-pneumatic tire comprising: a support structure including a urethane resin; and a tread located radially outward of the support structure and extending circumferentially along the tire, comprising: applying a first adhesive to an outer surface of the support structure in the tire radial direction and then drying the first adhesive; applying a second adhesive onto the first adhesive and then drying the second adhesive; a step of adhering a rubber composition for a tread to the surface of the support structure on which the first adhesive and the second adhesive have been applied in sequence, and then applying a pressure of 0.8 MPa or more to vulcanize and bond the support structure and the rubber composition for a tread together, the support structure has an arithmetic mean roughness Ra of an outer surface in the tire radial direction of 5.0 μm or more and 18.0 μm or less; the first adhesive is an epoxy resin adhesive, The method for manufacturing a non-pneumatic tire, wherein the second adhesive is a vulcanization adhesive containing a halogenated polymer and an acid acceptor, and the coating thickness is 5.0 μm or more and 20.0 μm or less.

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