Non-pneumatic tires

Abstract

To provide a non-pneumatic tire that can suppress the decrease in fracture stress of the support structure even after long-term use. [Solution] The non-pneumatic tire 1 comprises a support structure 10 and a tread 50 located outside the support structure 10 in the tire radial direction X and extending along the tire circumferential direction C. The support structure 10 comprises a resin, a first light stabilizer, and a second light stabilizer. The first light stabilizer is a hindered amine-based light stabilizer with a molecular weight of less than 550. The second light stabilizer is a hindered amine-based light stabilizer with a molecular weight of 1900 or more. In the non-pneumatic tire 1, the first light stabilizer is contained on one side of the support structure 10 from the center in the tire width direction, and the second light stabilizer is contained on the other side of the support structure 10 from the center in the tire width direction. When the non-pneumatic tire 1 is mounted on a vehicle body, one side in the tire width direction is the inside of the vehicle, and the other side in the tire width direction is the outside of the vehicle.

Description

Technical Field

[0001] The present invention relates to a non-pneumatic tire.

Background Art

[0002] Conventionally, a non-pneumatic tire including a support structure that supports a load from a vehicle body, and a tread that is located radially outside the support structure in the tire diameter direction and extends along the tire circumferential direction is known. Here, the support structure includes an inner annular portion, an outer annular portion that is coaxially arranged with the inner annular portion on the radially outer side of the inner annular portion in the tire diameter direction, and a plurality of spokes that connect the inner annular portion and the outer annular portion and are arranged along the tire circumferential direction.

[0003] Patent Document 1 describes a support structure including a resin and a light stabilizer. Here, the light stabilizer is a hindered amine light stabilizer having a molecular weight of 500 or more.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when a non-pneumatic tire is used for a long period of time, the breaking stress of the support structure decreases. This is presumably because light is likely to irradiate the outer surface of the support structure in the tire width direction, and thus the light stabilizer existing near the outer surface of the support structure in the tire width direction is likely to be consumed. Therefore, it is desired to suppress the decrease in the breaking stress of the support structure.

[0006] An object of the present invention is to provide a non-pneumatic tire capable of suppressing a decrease in the breaking stress of a support structure even when used for a long period of time.

Means for Solving the Problems

[0007] One aspect of the present invention relates to a non-pneumatic tire comprising a support structure and a tread located radially outward from the support structure and extending along the circumferential direction of the tire, wherein the support structure comprises a resin, a first light stabilizer, and a second light stabilizer, the first light stabilizer being a hindered amine light stabilizer having a molecular weight of less than 550, and the second light stabilizer being a hindered amine light stabilizer having a molecular weight of 1900 or more, the first light stabilizer being contained on one side of the support structure from the center in the tire width direction, and the second light stabilizer being contained on the other side of the support structure from the center in the tire width direction, and when mounted on a vehicle body, one side in the tire width direction is on the inside of the vehicle, and the other side in the tire width direction is on the outside of the vehicle. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a non-pneumatic tire that can suppress the decrease in fracture stress of the support structure even after long-term use. [Brief explanation of the drawing]

[0009] [Figure 1] This is a side view showing a non-pneumatic tire according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 3] Figure 2 is a perspective view of a portion of a non-pneumatic tire, seen from an oblique angle. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] Figure 1 shows a non-pneumatic tire according to one embodiment of the present invention. The non-pneumatic tire 1 comprises a support structure 10 and a tread 50. Here, the support structure 10 supports the load from the vehicle body. The tread 50 is located outside the support structure 10 in the tire radial direction X and extends along the tire circumferential direction C. Furthermore, the support structure 10 comprises an inner annular portion 20, an outer annular portion 30 arranged coaxially with the inner annular portion 20 on the outside of the inner annular portion 20 in the tire radial direction X, and a plurality of spokes 40 connecting the inner annular portion 20 and the outer annular portion 30 and arranged along the tire circumferential direction C. Details of the structure of the non-pneumatic tire 1 will be described later.

[0012] The support structure 10 comprises a resin, a first light stabilizer, and a second light stabilizer. The first light stabilizer is a hindered amine-based light stabilizer with a molecular weight of less than 550, and the second light stabilizer is a hindered amine-based light stabilizer with a molecular weight of 1900 or more. The non-pneumatic tire 1 contains the first light stabilizer on one side of the support structure 10 in the tire width direction, and the second light stabilizer on the other side of the support structure 10 in the tire width direction. When the non-pneumatic tire 1 is mounted on the vehicle body, one side in the tire width direction is the inside of the vehicle, and the other side in the tire width direction is the outside of the vehicle. Therefore, even if the non-pneumatic tire 1 is used for a long period of time, the decrease in the fracture stress of the support structure 10 is suppressed.

[0013] Here, when the non-pneumatic tire 1 is used for a long period of time, light is more easily irradiated onto the outer surface of the support structure 10 in the tire width direction, so the first and second light stabilizers contained on the outer surface are consumed more easily than those in the center in the tire width direction. On the other hand, light is less easily irradiated onto the inner surface of the support structure 10 in the tire width direction, so the first and second light stabilizers contained on the inner surface are consumed less easily than those in the center in the tire width direction. At this time, since the molecular weight of the first light stabilizer contained on the inner surface of the support structure 10 in the tire width direction is less than 550, the first light stabilizer is more likely to migrate to the outer surface of the support structure 10 in the tire width direction than the center, and as a result, it is presumed that the decrease in the fracture stress of the support structure 10 is suppressed. On the other hand, since the molecular weight of the second light stabilizer contained on the outer surface of the support structure 10 in the tire width direction is 1900 or more, bleed-out of the second light stabilizer is suppressed, and as a result, the decrease in the fracture stress of the support structure 10 is suppressed.

[0014] The molecular weight of the first light stabilizer is, for example, 200 or more. The molecular weight of the second light stabilizer is, for example, 4000 or less.

[0015] In this case, the ratio A of the first light stabilizer to the second light stabilizer may be uniform in the tire width direction of the support structure 10, but multiple layers with different ratios A may be laminated in the tire width direction. In this case, it is preferable that the ratio A in the first layer located on one side in the tire width direction is greater than the ratio A in the second layer located on the other side in the tire width direction than the first layer. This makes it possible to increase the amount of the first light stabilizer that migrates outward from the center of the support structure 10 in the tire width direction, thereby further suppressing the decrease in the fracture stress of the support structure 10.

[0016] The ratio of the thickness of the second layer to the thickness of the first layer is not particularly limited, but for example, it is 0.25 or more and 4 or less. In this case, it is preferable that the first layer is formed in a region including the center of the support structure 10 in the tire width direction, so that the first light stabilizer can easily migrate to the outside of the vehicle from the center of the support structure 10 in the tire width direction.

[0017] The number of stacked layers of multiple layers is not particularly limited as long as it is 2 or more, but for example, it is 5 or less.

[0018] Examples of commercially available products of the first light stabilizer include, for example, Adeka Stab LA-77Y with a molecular weight of 480, Adeka Stab LA-82 with a molecular weight of 239 (both manufactured by ADEKA), Tinuvin 249 with a molecular weight of 482, and Tinuvin 292 which is a mixture of light stabilizers with molecular weights of 370 and 509 (both manufactured by BASF). Examples of commercially available products of the second light stabilizer include, for example, Adeka Stab LA-63P with a molecular weight of 2000 (manufactured by ADEKA), and Tinuvin 111FDL with a molecular weight of 2500 (manufactured by BASF).

[0019] The total content of the first light stabilizer and the second light stabilizer in the support structure 10 is preferably 0.05% by mass or more and 1.5% by mass or less, and more preferably 0.1% by mass or more and 0.5% by mass or less. When the total content of the first light stabilizer and the second light stabilizer in the support structure 10 is 0.05% by mass or more, even if the non-pneumatic tire 1 is used for a long time, the decrease in the breaking stress of the support structure 10 is suppressed, and when it is 1.5% by mass or less, the bleed-out of the first light stabilizer and the second light stabilizer is suppressed.

[0020] The mass ratio of the second light stabilizer to the first light stabilizer in the first layer is, for example, 0 or more and 7 / 3 or less. Also, the mass ratio of the first light stabilizer to the second light stabilizer in the second layer is, for example, 0 or more and 7 / 3 or less.

[0021] In addition to the resin, the first light stabilizer, and the second light stabilizer, the support structure 10 may further contain an ultraviolet blocker, an ultraviolet absorber, an antioxidant, a reinforcing material, a pigment, etc.

[0022] The material constituting the support structure 10 is not particularly limited, and examples include thermoplastic elastomers, crosslinked rubbers, and other resins, and two or more kinds may be used in combination.

[0023] Examples of thermoplastic elastomers include polyester elastomers, polyolefin elastomers, polyamide elastomers, polystyrene elastomers, polyvinyl chloride elastomers, and polyurethane elastomers. The rubber constituting the crosslinked rubber can be either natural rubber or synthetic rubber. Examples of synthetic rubbers 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. Other resins can be either thermoplastic resins or thermosetting resins. Examples of thermoplastic resins include polyethylene resin, polystyrene resin, and polyvinyl chloride resin. Examples of thermosetting resins include epoxy resin, phenolic resin, polyurethane resin, silicone resin, polyimide resin, and melamine resin. Among these, urethane resin is preferred from the viewpoint of moldability and processability of the support structure 10.

[0024] The support structure 10 may be a cured product of a composition containing a resin precursor, a first light stabilizer, and a second light stabilizer. In this case, for example, the support structure 10 can be manufactured by molding a thermosetting resin composition containing a resin precursor, a first light stabilizer, and a second light stabilizer using a mold, and then curing it. When manufacturing a support structure 10 in which multiple layers with different ratios A are laminated in the tire width direction, multiple thermosetting resin compositions with different ratios A are laminated and then cured. Alternatively, the support structure 10 may be manufactured by bonding a pre-molded inner annular portion 20, an outer annular portion 30, and spokes 40 together.

[0025] If the support structure 10 contains urethane resin, the thermosetting resin composition preferably contains polyol and polyisocyanate as precursors of the urethane resin.

[0026] The polyol is not particularly limited as long as it has multiple hydroxyl groups, but examples include low molecular weight polyols, polyether polyols, and polyester polyols, and two or more types may be used in combination. Among these, low molecular weight polyols and polyether polyols are preferred.

[0027] Examples of low molecular weight polyols include aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, methyloctanediol, and 1,9-nonanediol; alicyclic diols such as 1,4-cyclohexanediol; and 1,4-bis(β-hydroxyethoxy)benzene, hydroquinone, resorcinol, chlorohydroquinone, bromohydroquinone, methylhydroquinone, phenylhydroquinone, and methoxyquinone. Examples include aromatic diols such as droquinone, phenoxyhydroquinone, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxydiphenylmethane, bisphenol A, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,2-bis(4-hydroxyphenoxy)ethane, 1,4-dihydroxynaphthalene, and 2,6-dihydroxynaphthalene. Among these, 1,4-butanediol is preferred.

[0028] Examples of polyether polyols include polytetramethylene glycol, polyethylene glycol, and polypropylene glycol. Among these, polytetramethylene glycol is preferred. The number-average molecular weight of the polyether polyol is, for example, 200 to 3000.

[0029] Examples of polyester polyols include polyadipate glycol, polyphthalate glycol, polycarbonate diol, and polycaprolactone polyol. The number-average molecular weight of polyester polyols is, for example, between 200 and 3000.

[0030] The polyisocyanate is not particularly limited as long as it has multiple isocyanate groups, but examples include low molecular weight polyisocyanates and urethane prepolymers, and two or more may be used in combination. Among these, urethane prepolymers are preferred.

[0031] Examples of low molecular weight polyisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modified MDI, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate (PPDI), 1,3-phenylene diisocyanate, and 1,4-xy Examples include aromatic diisocyanates such as reylene diisocyanate and 1,3-xylylene diisocyanate, aliphatic diisocyanates such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate and 1,6-hexamethylene diisocyanate, and alicyclic diisocyanates such as 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate and norbornane diisocyanate. Among these, 1,4-phenylenediisocyanate is preferred.

[0032] The urethane prepolymer is synthesized by polyaddition of an excess of low molecular weight polyisocyanate and a polyol, and has isocyanate groups at its terminals. Here, the low molecular weight polyisocyanate and polyol used in the synthesis of the urethane prepolymer are the same as those used in thermosetting resin compositions, but may be identical or different from those used in thermosetting resin compositions.

[0033] The isocyanate index of the thermosetting resin composition is not particularly limited, but for example, it is between 1.00 and 1.10. Here, the isocyanate index of the thermosetting resin composition is the molar ratio of isocyanate groups in the polyisocyanate constituting the thermosetting resin composition to the hydroxyl groups in the polyol constituting the thermosetting resin composition.

[0034] A non-pneumatic tire 1 can be manufactured, for example, by vulcanizing and bonding a support structure 10 and a tread rubber composition using a vulcanizing adhesive. At this time, for example, the outer surface of the outer annular portion 30 of the support structure 10 is roughened. This improves the adhesion between the support structure 10 and the tread 50. The method for roughening the outer surface of the outer annular portion 30 is not particularly limited, but for example, buffing can be used. Next, a vulcanizing adhesive is applied to the roughened outer surface of the outer annular portion 30 and allowed to dry. Then, the tread rubber composition is wrapped around the outer surface of the outer annular portion 30 to which the vulcanizing adhesive has been applied, and then vulcanized and bonded.

[0035] The tread rubber composition may, for example, include natural rubber and carbon black, and may further contain sulfur, silica, etc. Here, the tread rubber composition may contain synthetic rubber such as polyisoprene rubber or styrene-butadiene rubber together with natural rubber, or in place of natural rubber.

[0036] The following describes the structure of the non-pneumatic tire 1 in detail. Figure 1 is a side view of the non-pneumatic tire 1, taken from a direction parallel to the tire rotation axis (tire meridian), that is, from a direction along the front-to-back direction of the paper in Figure 1. The non-pneumatic tire 1 shown in Figure 1 is in an unloaded state. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a partial perspective view of the non-pneumatic tire 1, taken from an oblique angle from the part shown in Figure 2.

[0037] In Figures 1 and 3, C represents the circumferential direction of the tire. In Figures 1-3, X represents the radial direction of the tire. In Figures 2 and 3, Y represents the width direction of the tire. In Figure 1, the tire width direction Y is the front-to-back direction of the paper. In Figure 2, E represents the tire equatorial plane. In Figure 2, the tire circumferential direction C is the front-to-back direction of the paper.

[0038] The tire circumferential direction C is the direction around the tire rotation axis and is the same direction in which the non-pneumatic tire 1 rotates. The tire radial direction X is the direction perpendicular to the tire rotation axis. The tire width direction Y is the direction parallel to the tire rotation axis. In Figures 2 and 3, one side of the tire width direction Y is shown as Y1 and the other side of the tire width direction Y is shown as Y2. The tire equatorial plane E shown in Figure 2 is a plane perpendicular to the tire rotation axis and is located at the center of the tire width direction Y.

[0039] Note that the thickness of the inner annular portion 20 and the outer annular portion 30 is the dimension in the tire radial direction X. Also, the width of the inner annular portion 20 and the outer annular portion 30 is the dimension in the tire width direction Y, as shown in Figure 2.

[0040] The inner annular portion 20 is an annular part along the tire circumferential direction C that constitutes the inner circumference of the non-pneumatic tire 1. The thickness and width of the inner annular portion 20 are set to be constant in order to improve uniformity. A tire wheel is placed in the space on the inner circumference side of the inner annular portion 20. The inner circumference of the inner annular portion 20 is fitted and mounted onto the outer circumference of the rim of the tire wheel. With the inner annular portion 20 mounted on the rim, the non-pneumatic tire 1 is mounted on the tire wheel. The inner circumferential surface of the inner annular portion 20 may be provided with fitting portions consisting of protrusions, grooves, etc., for fitting with the rim.

[0041] 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 weight reduction and durability while satisfying the function of sufficiently transmitting rotational force to the spokes 40. The thickness of the inner annular portion 20 is not particularly limited, but for example, it is preferably 2% to 7% of the tire cross-sectional height H shown in Figure 2, and more preferably 3% to 6%.

[0042] The inner diameter of the inner annular portion 20 is determined according to the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the intended use of the vehicle, etc. For example, when considering a replacement for a general pneumatic tire, the inner diameter of the inner annular portion 20 may be, for example, 250 mm or more and 500 mm or less, but is not limited to this.

[0043] The width of the inner annular portion 20 is determined appropriately according to the intended use of the vehicle on which the non-pneumatic tire 1 is fitted, the length of the axle, etc. For example, when considering a replacement for a general pneumatic tire, the width of the inner annular portion 20 may be between 100 mm and 300 mm, but is not limited to this.

[0044] The outer annular portion 30 is an annular part along the tire circumferential direction C that constitutes the outer circumference of the non-pneumatic tire 1. The outer annular portion 30 is arranged concentrically with the inner annular portion 20 on its outer circumference side. The thickness and width of the outer annular portion 30 are set to be constant in order to improve uniformity.

[0045] The outer annular portion 30 transmits the rotation of the inner annular portion 20 and 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 weight reduction and durability while satisfying 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 for example, it is preferably 2% to 7% of the tire cross-sectional height H shown in Figure 2, and more preferably 2% to 5%.

[0046] The inner diameter of the outer annular portion 30 is determined appropriately according to the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the intended use of the vehicle, etc. For example, when considering a replacement for a general pneumatic tire, the inner diameter of the outer annular portion 30 may be between 420 mm and 750 mm, but is not limited to this.

[0047] The width of the outer annular portion 30 is determined appropriately according to the intended use of the vehicle on which the non-pneumatic tire 1 is fitted. For example, when considering a replacement for a general pneumatic tire, the width of the outer annular portion 30 may be between 100 mm and 300 mm, but is not limited to this.

[0048] Multiple 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 multiple spokes 40, are arranged concentrically with respect to each other. Each of the multiple spokes 40 is arranged independently along the tire circumferential direction C. As shown in Figure 1, when the non-pneumatic tire 1 is unloaded, the multiple spokes 40 extend linearly in the radial direction, approximately parallel to the tire radial direction X, when viewed from the side.

[0049] As shown in Figures 2 and 3, the spokes 40 of this embodiment include a plurality of first spokes 41 and a plurality of second spokes 42. The extending direction of both the first spokes 41 and the second spokes 42 is not parallel to the tire radial direction X when viewed 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 from the first spokes 41. The first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction C.

[0050] More specifically, as shown in Figures 2 and 3, the first spoke 41 extends inclined from the Y1 side, which is one side of the outer annular portion 30 in the tire width direction Y, toward the Y2 side, which is the other side of the inner annular portion 20 in the tire width direction Y. The second spoke 42 extends inclined from the Y2 side, which is the other side of the outer annular portion 30 in the tire width direction Y, toward the Y1 side, which is one side of the inner annular portion 20 in the tire width direction Y.

[0051] The inclination angles of the first spoke 41 and the second spoke 42 are the same. Therefore, when viewed from a direction along the tire circumferential direction C, the first spoke 41 and the second spoke 42 adjacent to each other in the tire circumferential direction C are arranged in a roughly X shape. As shown in Figure 2, the first spoke 41 and the second spoke 42 are inclined at an angle θ with respect to the tire width direction Y, and it is preferable that this angle θ is, for example, 30° or more and 60° or less.

[0052] As shown in Figure 2, when viewed from a direction along the tire circumferential direction C, the first spoke 41 and the second spoke 42 each have the same shape, symmetrical with respect to the tire equatorial plane E. Therefore, in the following, there is no need to distinguish between the first spoke 41 and the second spoke 42, and when they can be described together, the first spoke 41 and the second spoke 42 will be collectively referred to as spoke 40.

[0053] The spokes 40 are plate-shaped and extend diagonally from the inner annular portion 20 toward the outer annular portion 30 at an angle θ as described above. As shown in Figure 3, the plate thickness t of the spokes 40 along the tire circumferential direction is smaller than the plate width w, and the direction of the plate thickness t is along the tire circumferential direction C. That is, the spokes 40 are formed in a plate shape that extends along the plane of the tire radial direction X and the tire width direction Y. The plate width w referred to here is the dimension in the direction perpendicular to the inclination direction on which the spokes 40 extend, when the spokes 40 are viewed from the direction along the tire circumferential direction C, as also shown in Figure 2. In this embodiment, the plate thickness t of all spokes 40 is the same. Also, the plate width w of all spokes 40 is the same.

[0054] Since the spokes 40 are long, plate-shaped, even if the plate thickness t is reduced, the durability of the spokes 40 can be improved by setting a wider plate width w. Furthermore, by reducing the plate thickness t and increasing the number of spokes 40, the spacing between adjacent spokes 40 in the tire circumferential direction C can be reduced while maintaining the overall rigidity of the non-pneumatic tire 1. This distributes the contact pressure during tire rolling by the spokes 40, thereby reducing the contact pressure.

[0055] In addition, while the spokes 40 are parallel to the tire radial direction X in a side view, the spokes 40 may also be arranged diagonally with respect to the tire radial direction X so as to intersect with the tire radial direction X in a side view.

[0056] As shown in Figures 2 and 3, the first spoke 41 has a first inner connecting portion 411 that connects to the inner annular portion 20 on the tire width direction Y2 side, and a first outer connecting portion 412 that connects to the outer annular portion 30 on the tire width direction Y1 side. The second spoke 42 has a second inner connecting portion 421 that connects to the inner annular portion 20 on the tire width direction Y1 side, and a second outer connecting portion 422 that connects to the outer annular portion 30 on the tire width direction Y2 side. The first outer connecting portion 412 and the second outer connecting portion 422 are examples of connecting portions of the spoke 40 connected to the outer annular portion 30 in this embodiment.

[0057] As shown in Figure 2, the first inner connecting portion 411 of the first spoke 41 has a shape that widens along the tire width direction Y as it approaches the inner annular portion 20. The side surface 411a of the first inner connecting portion 411 on the tire width direction Y2 side extends in a gentle curve to the end 20b of the inner annular portion 20 on the tire width direction Y2 side. The side surface 411b of the first inner connecting portion 411 on the tire width direction Y1 side extends in a curve toward the tire width direction Y1 to the position of the tire equatorial plane E of the inner annular portion 20.

[0058] The first outer connecting portion 412 of the first spoke 41 has the same shape as the first inner connecting portion 411, and has a shape that widens along the tire width direction as it approaches the outer annular portion 30. The side surface 412a of the first outer connecting portion 412 on the tire width direction Y1 side extends in a gentle curve to the end 30a of the outer annular portion 30 on the tire width direction Y1 side. The side surface 412b of the first outer connecting portion 412 on the tire width direction Y2 side extends in a curve toward the tire width direction Y2 to the position of the tire equatorial plane E of the outer annular portion 30.

[0059] The first inner connecting portion 411 is provided in half of the inner annular portion 20 on the tire width direction Y2 side. The first outer connecting portion 412 is provided in half of the outer annular portion 30 on the tire width direction Y1 side.

[0060] As shown in Figure 2, the second inner connecting portion 421 of the second spoke 42 has a shape that widens along the tire width direction Y as it approaches the inner annular portion 20. The side surface 421a of the second inner connecting portion 421 on the tire width direction Y1 side extends in a gentle curve to the end 20a of the inner annular portion 20 on the tire width direction Y1 side. The side surface 421b of the second inner connecting portion 421 on the tire width direction Y2 side extends in a curve toward the tire width direction Y2 to the position of the tire equatorial plane E of the inner annular portion 20.

[0061] The second outer connecting portion 422 of the second spoke 42 has the same shape as the second inner connecting portion 421, and has a shape that widens along the tire width direction as it approaches the outer annular portion 30. The side surface 422a of the second outer connecting portion 422 on the tire width direction Y2 side extends in a gentle curve to the end 30b of the outer annular portion 30 on the tire width direction Y2 side. The side surface 422b of the second outer connecting portion 422 on the tire width direction Y1 side extends in a curve toward the tire width direction Y1 to the position of the tire equatorial plane E of the outer annular portion 30.

[0062] The second inner connecting portion 421 is provided in half of the inner annular portion 20 on the tire width direction Y1 side. The second outer connecting portion 422 is provided in half of the outer annular portion 30 on the tire width direction Y2 side.

[0063] As described above, the plate thickness t of all spokes 40 in this embodiment is the same. The dimension of the plate thickness t is not particularly limited, but in order for the spokes 40 to receive sufficient rotational force from the inner annular portion 20 and the outer annular portion 30, and to be able to deform appropriately when a load is applied, it is preferably 1 mm to 30 mm, and more preferably 5 mm to 25 mm.

[0064] As described above, the plate width w of all spokes 40 in this embodiment is the same. The plate width w of the spokes 40 is not particularly limited, but it is preferably 5 mm to 25 mm, and more preferably 10 mm to 20 mm, in order to sufficiently receive rotational force from the inner annular portion 20 and the outer annular portion 30, while also allowing for appropriate deflection and deformation when a load is applied. Furthermore, from the viewpoint of improving durability and distributing the ground pressure, the plate width w is preferably 110% or more of the plate thickness t, and more preferably 115% or more.

[0065] 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, reduce weight, and improve both power transmission and durability.

[0066] The tread 50 is provided on the outer circumferential surface of the outer annular portion 30 and constitutes the outermost periphery of the non-pneumatic tire 1. The tread 50 has a tread surface 51 on its outer circumferential surface that contacts the road surface. The tread surface 51 of the tread 50 is provided with a tread pattern formed by multiple grooves and land areas, similar to conventional pneumatic tires.

[0067] Furthermore, the tread 50 may have a structure in which multiple vulcanized rubber layers with different components and properties are laminated together (for example, two or three layers).

[0068] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and the above embodiments may be modified as appropriate within the scope of the spirit of the present invention.

[0069] The configuration of the embodiment of the present invention is as follows.

[0070] (1) A non-pneumatic tire comprising a support structure and a tread located radially outward from the support structure and extending along the circumferential direction of the tire, wherein the support structure comprises a resin, a first light stabilizer, and a second light stabilizer, the first light stabilizer being a hindered amine light stabilizer having a molecular weight of less than 550, and the second light stabilizer being a hindered amine light stabilizer having a molecular weight of 1900 or more, the first light stabilizer being contained on one side of the support structure from the center in the tire width direction, and the second light stabilizer being contained on the other side of the support structure from the center in the tire width direction, and when mounted on a vehicle body, one side in the tire width direction is on the inside of the vehicle and the other side in the tire width direction is on the outside of the vehicle.

[0071] (2) The non-pneumatic tire according to (1), wherein the support structure is made up of multiple layers having different ratios of the first light stabilizer to the second light stabilizer, laminated in the tire width direction.

[0072] (3) The non-pneumatic tire according to (2), wherein the ratio of the first layer located on one side in the tire width direction is greater than the ratio of the second layer located on the other side in the tire width direction than the first layer.

[0073] (4) The support structure is a non-pneumatic tire according to any one of (1) to (3), wherein the total content of the first light stabilizer and the second light stabilizer is 0.05% by mass or more and 1.5% by mass or less.

[0074] (5) The non-pneumatic tire according to any one of (1) to (4), wherein the resin is urethane resin.

[0075] (6) The non-pneumatic tire according to any one of (1) to (5), wherein the support structure comprises an inner annular portion, an outer annular portion arranged coaxially with the inner annular portion on the radially outer side of the inner annular portion in the tire direction, and a plurality of spokes connecting the inner annular portion and the outer annular portion and arranged along the circumferential direction of the tire. [Examples]

[0076] The following describes embodiments of the present invention, but the present invention is not limited to these embodiments. Since it is difficult to measure the fracture stress of the support structure, in this embodiment, the fracture stress of a sample sheet simulating the support structure was measured.

[0077] [Examples 1-6, Comparative Examples 1 and 2] Adiprene LFP E560 (manufactured by LANXESS) as a urethane prepolymer, VibraCure A250 (manufactured by LANXESS) as 1,4-butanediol, and PTMG1000 (manufactured by Mitsubishi Chemical) as polytetramethylene ether glycol were weighed in a mass ratio of 123:7:3. Next, the mixture was stirred using a hybrid mixer (manufactured by Kurabo Industries Ltd.), followed by vacuum degassing to obtain a precursor of urethane resin.

[0078] After weighing the urethane resin precursor, the first light stabilizer, and the second light stabilizer according to the formulation [mass%] shown in Table 1, the mixture was stirred using a hybrid mixer (manufactured by Kurabo Industries Ltd.) to obtain a thermosetting resin composition. Next, the thermosetting resin composition was poured into a mold with a frame measuring 120 mm in width, 200 mm in length, and 1 mm in height, and then cured in an oven at 130°C for 16 hours to obtain a sample sheet.

[0079] The details of the light stabilizers in Table 1 are as follows:

[0080] LA-82: Hindered amine-based light stabilizer with a molecular weight of 239 (manufactured by ADEKA) Tinuvin249: A hindered amine-based light stabilizer with a molecular weight of 482 (manufactured by BASF). Tinuvin292: A mixture of hindered amine-based light stabilizers with molecular weights of 370 and 509 (manufactured by BASF). LA-63P: Hindered amine-based light stabilizer with a molecular weight of 2000 (manufactured by ADEKA) Tinuvin111FDL: A hindered amine-based light stabilizer with a molecular weight of 2500 (manufactured by BASF).

[0081] [Exposure test] Using a super xenon weather meter (Suga Test Instruments), an exposure test of 720 hours was conducted on one side of a sample sheet under the following conditions, in accordance with JIS K7350-2. Ambient temperature: 38℃ Ambient humidity: 50%RH Black panel temperature: 65℃ Wavelength of light emitted from the light source: 300-400nm Illuminance of light emitted from the light source: 180 W / m 2

[0082] [Retention rate of fracture stress] Using a universal testing machine (manufactured by Shimadzu Corporation), in accordance with JIS K7161-1, 2 mm thick test specimens punched out of sample sheets before and after exposure testing with a No. 3 dumbbell were pulled at a tensile speed of 300 mm / min, and the fracture stress was measured. Next, the formula (Fracture stress after exposure test) / (Fracture stress before exposure test) × 100 The retention rate of fracture stress was determined by this method.

[0083] Table 1 shows the evaluation results of the fracture stress of the sample sheet.

[0084] [Table 1]

[0085] Table 1 shows that the sample sheets of Examples 1 to 6 have a high retention rate of fracture stress. In contrast, the sample sheet of Comparative Example 1 has a low retention rate of fracture stress because it does not contain the first light stabilizer. Also, the test specimen of Comparative Example 2 has a low retention rate of fracture stress because it does not contain the second light stabilizer.

[0086] [Examples 7-9, Comparative Example 3] After weighing the urethane resin precursor, the first light stabilizer, and the second light stabilizer according to the formulations [mass%] shown in Table 2, the mixture was stirred using a hybrid mixer (manufactured by Kurabo Industries Ltd.) to obtain the thermosetting resin composition for the first layer and the thermosetting resin composition for the second layer. Next, the thermosetting resin composition for the first layer and the thermosetting resin composition for the second layer were sequentially poured into a mold with a frame measuring 120 mm in width, 200 mm in length, and 1 mm in height, and then cured in an oven at 130°C for 16 hours to obtain a sample sheet.

[0087] [Exposure test] Using a super xenon weather meter (Suga Test Instruments), a 720-hour exposure test was conducted on the second layer of the sample sheet under the following conditions, in accordance with JIS K7350-2. Ambient temperature: 38℃ Ambient humidity: 50%RH Black panel temperature: 65℃ Wavelength of light emitted from the light source: 300-400nm Illuminance of light emitted from the light source: 180 W / m 2

[0088] [Retention rate of fracture stress] Using a universal testing machine (manufactured by Shimadzu Corporation), in accordance with JIS K7161-1, 2 mm thick test specimens punched out of sample sheets before and after exposure testing with a No. 3 dumbbell were pulled at a tensile speed of 300 mm / min, and the fracture stress was measured. Next, the formula (Fracture stress after exposure test) / (Fracture stress before exposure test) × 100 The retention rate of fracture stress was determined by this method.

[0089] Table 2 shows the evaluation results of the fracture stress of the sample sheet.

[0090] [Table 2]

[0091] Table 2 shows that the sample sheets of Examples 7-9 have a high retention rate of fracture stress. In contrast, the sample sheet of Comparative Example 3 has a low retention rate of fracture stress because the first layer, which corresponds to the inside of the vehicle, does not contain the first light stabilizer, and the second layer, which corresponds to the outside of the vehicle, does not contain the second light stabilizer. [Explanation of Symbols]

[0092] 1. Non-pneumatic tires 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 C Tire circumferential direction E Tire Equatorial Plane O axis center X Tire radial direction Y tire width direction

Claims

1. The system comprises a support structure and a tread located radially outward from the support structure and extending along the circumferential direction of the tire. The support structure comprises a resin, a first light stabilizer, and a second light stabilizer. The first light stabilizer is a hindered amine-based light stabilizer with a molecular weight of less than 550. The second light stabilizer is a hindered amine-based light stabilizer with a molecular weight of 1900 or more. The first light stabilizer is contained on one side of the support structure, rather than on the side of the center in the tire width direction. The second light stabilizer is contained on the side of the support structure other than the center in the tire width direction, A non-pneumatic tire in which, when mounted on a vehicle body, one side in the tire width direction is on the inside of the vehicle and the other side in the tire width direction is on the outside of the vehicle.

2. The non-pneumatic tire according to claim 1, wherein the support structure is formed by laminating a plurality of layers in the tire width direction, each having a different ratio of the first light stabilizer to the second light stabilizer.

3. The non-pneumatic tire according to claim 2, wherein the ratio of the first layer located on one side in the tire width direction is greater than the ratio of the second layer located on the other side in the tire width direction than the first layer.

4. The support structure is a non-pneumatic tire according to any one of claims 1 to 3, wherein the total content of the first light stabilizer and the second light stabilizer is 0.05% by mass or more and 1.5% by mass or less.

5. The non-pneumatic tire according to any one of claims 1 to 3, wherein the resin is a urethane resin.

6. The non-pneumatic tire according to any one of claims 1 to 3, wherein the support structure comprises an inner annular portion, an outer annular portion arranged coaxially with the inner annular portion on the radially outer side of the inner annular portion in the tire direction, and a plurality of spokes connecting the inner annular portion and the outer annular portion and arranged along the circumferential direction of the tire.

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