Method for manufacturing non-pneumatic tire

Abstract

To provide a method for manufacturing a non-pneumatic tire that can improve a mold-injecting property of a thermosetting resin composition and suppress occurrence of a sink mark in a support structure.SOLUTION: A method for manufacturing a non-pneumatic tire 1 is a method for manufacturing a non-pneumatic tire 1 comprising a support structure 10. The method for manufacturing the non-pneumatic tire 1 includes a step of injecting a thermosetting resin composition containing a polyol and a polyisocyanate into a mold, and a step of thermally curing the thermosetting resin composition injected into the mold to obtain at least a portion of the support structure 10. A temperature of the thermosetting resin composition injected into the mold is 50°C or more and 70°C or less, and a temperature of the mold into which the thermosetting resin composition is injected is in a range of 15°C or more and 40°C or less lower than the temperature of the thermosetting resin composition injected into the mold.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, a non-pneumatic tire is known that includes a support structure for supporting a load from a vehicle, and a tread located radially outside the support structure in the tire diameter direction and extending along the tire circumferential direction. At this time, the support structure includes an inner annular portion, an outer annular portion 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 connecting the inner annular portion and the outer annular portion and arranged along the tire circumferential direction.

[0003] Patent Document 1 describes a method for manufacturing a non-pneumatic tire, which includes a step of preparing a raw material liquid of a thermosetting resin so that the liquid viscosity becomes 600 to 6000 mPa·s, a step of stirring and defoaming the prepared raw material liquid of the thermosetting resin, and a step of injecting the defoamed raw material liquid of the thermosetting resin into a mold and curing it to mold a support structure.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, it is desired to improve the castability of the raw material liquid and suppress the occurrence of sink marks in the support structure.

[0006] An object of the present invention is to provide a method for manufacturing a non-pneumatic tire capable of improving the castability of a thermosetting resin composition and suppressing the occurrence of sink marks in the support structure.

Means for Solving the Problems

[0007] One aspect of the present invention is a method for manufacturing a non-pneumatic tire including a support structure, the method including injecting a thermosetting resin composition including a polyol and a polyisocyanate into a mold, and thermosetting the thermosetting resin composition injected into the mold to obtain at least a part of the support structure, wherein the temperature of the thermosetting resin composition injected into the mold is 50°C or higher and 70°C or lower, and the temperature of the mold into which the thermosetting resin composition is injected is 15°C or higher and 40°C or lower lower than the temperature of the thermosetting resin composition injected into the mold.

Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for manufacturing a non-pneumatic tire that improves the castability of a thermosetting resin composition and suppresses the occurrence of sink marks in a support structure.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] [Method for Manufacturing Non-Pneumatic Tire] The method for manufacturing a non-pneumatic tire according to the present embodiment is a method for manufacturing a non-pneumatic tire including a support structure described later. The method for manufacturing a non-pneumatic tire according to the present embodiment includes injecting a thermosetting resin composition including a polyol and a polyisocyanate into a mold, and thermosetting the thermosetting resin composition injected into the mold to obtain a support structure.

[0012] Instead of obtaining the support structure, a part of the support structure may be obtained. Examples of the part of the support structure include an inner annular portion, an outer annular portion, and spokes. Further, the non-pneumatic tire may further include a member corresponding to a tread, a reinforcing layer, a fitting member for an axle or a rim, and the like.

[0013] The temperature of the thermosetting resin composition to be injected into the mold is 50°C or higher and 70°C or lower, preferably 50°C or higher and 55°C or lower. When the temperature of the thermosetting resin composition to be injected into the mold is less than 50°C, the injectability of the thermosetting resin composition decreases as the viscosity of the thermosetting resin composition increases. When it exceeds 70°C, the injectability of the thermosetting resin composition decreases as the thermosetting resin composition thermosets.

[0014] The temperature of the mold into which the thermosetting resin composition is injected is preferably 15°C or higher and 40°C or lower, more preferably 30°C or higher and 40°C or lower, lower than the temperature of the thermosetting resin composition to be injected into the mold. When the difference between the temperature of the mold into which the thermosetting resin composition is injected and the temperature of the thermosetting resin composition to be injected into the mold is less than 15°C, sink marks on the support structure and cracks in the spokes are likely to occur. When it exceeds 40°C, the injectability of the thermosetting resin composition decreases as the viscosity of the thermosetting resin composition in contact with the mold increases.

[0015] When thermosetting the thermosetting resin composition in an environment of 130°C or lower, the time required for the temperature of the mold to reach 100°C is 180 minutes or more, preferably 185 minutes or more. When the time required for the temperature of the mold to reach 100°C is 180 minutes or more when thermosetting the thermosetting resin composition in an environment of 130°C or lower, sink marks on the support structure are less likely to occur. Note that the time required for the temperature of the mold to reach 100°C when thermosetting the thermosetting resin composition in an environment of 130°C or lower is, for example, 230 minutes or less.

[0016] As the polyol, as long as it has a plurality of hydroxyl groups, it is not particularly limited. For example, low molecular weight polyols, polyether polyols, and polyester polyols can be mentioned, and two or more of them may be used in combination. Among these, low molecular weight polyols and polyether polyols are preferred.

[0017] Examples of the low molecular weight polyol 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, 1,9 - nonanediol; alicyclic diols such as 1,4 - cyclohexanediol; aromatic diols such as 1,4 - bis(β - hydroxyethoxy)benzene, hydroquinone, resorcinol, chlorohydroquinone, bromohydroquinone, methylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4,4’ - dihydroxybiphenyl, 4,4’ - dihydroxydiphenyl ether, 4,4’ - dihydroxydiphenyl sulfide, 4,4’ - dihydroxydiphenyl sulfone, 4,4’ - dihydroxybenzophenone, 4,4’ - dihydroxydiphenyl methane, bisphenol A, 1,1 - bis(4 - hydroxyphenyl)cyclohexane, 1,2 - bis(4 - hydroxyphenoxy)ethane, 1,4 - dihydroxynaphthalene, 2,6 - dihydroxynaphthalene. Among these, 1,4 - butanediol is preferred.

[0018] Examples of the polyether polyol 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 or more and 3000 or less.

[0019] Examples of the polyester polyol include polyadipate glycol, polyphthalic acid glycol, polycarbonate diol, and polycaprolactone polyol. The number average molecular weight of the polyester polyol is, for example, 200 or more and 3000 or less.

[0020] The polyisocyanate is not particularly limited as long as it has a plurality of isocyanate groups. Examples thereof include low molecular weight polyisocyanates and urethane prepolymers, and two or more thereof may be used in combination. Among these, urethane prepolymers are preferred.

[0021] Examples of the low molecular weight polyisocyanate include aromatic diisocyanates such as 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, 1,4-xylylene 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-phenylene diisocyanate is preferred.

[0022] 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 the thermosetting resin composition, but they may be the same as or different from the low molecular weight polyisocyanate and polyol used in the thermosetting resin composition.

[0023] The isocyanate index of the thermosetting resin composition is not particularly limited, but is, for example, 1.00 or more and 1.10 or less. Here, the isocyanate index of the thermosetting resin composition is the molar ratio of the isocyanate groups of the polyisocyanate constituting the thermosetting resin composition to the hydroxyl groups of the polyol constituting the thermosetting resin composition.

[0024] [Non-pneumatic tire] Fig. 1 shows an example of a non-pneumatic tire. The non-pneumatic tire 1 includes a support structure 10 and a tread 50. Here, the support structure 10 supports the load from the vehicle. Further, the tread 50 is located outside the support structure 10 in the tire radial direction X, and extends along the tire circumferential direction C. The support structure 10 includes an inner annular portion 20, an outer annular portion 30 coaxially arranged outside 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. The details of the structure of the non-pneumatic tire 1 will be described later.

[0025] The inner annular portion 20, the outer annular portion 30, and the spokes 40 are obtained by injecting the thermosetting resin composition into a mold and then thermosetting it. When the materials constituting the inner annular portion 20, the outer annular portion 30, and the spokes 40 are the same, for example, the inner annular portion 20, the outer annular portion 30, and the spokes 40 can be integrally molded by a casting method.

[0026] Note that a part of the inner annular portion 20, the outer annular portion 30, and the spoke 40 may be obtained by injecting a thermosetting resin composition into a mold and then thermosetting it as described above. In this case, the remaining portions of the inner annular portion 20, the outer annular portion 30, and the spoke 40 are made of a known elastic material.

[0027] The non-pneumatic tire 1 can be obtained, for example, by vulcanizing and adhering a support structure 10 and a tread rubber composition using a vulcanizing adhesive. Specifically, first, the outer peripheral surface of the outer annular portion 30 of the support structure 10 is roughened. This increases the adhesiveness between the support structure 10 and the tread 50. The method of roughening the outer peripheral surface of the outer annular portion 30 is not particularly limited, and examples include buffing. Next, a vulcanizing adhesive is applied to the roughened outer peripheral surface of the outer annular portion 30 and dried. Next, after winding the tread rubber composition around the outer peripheral surface of the outer annular portion 30 to which the vulcanizing adhesive has been applied, vulcanizing adhesion is performed.

[0028] The tread rubber composition includes, for example, natural rubber and carbon black, and may further include sulfur, silica, etc. Here, the tread rubber composition may include a synthetic rubber such as polyisoprene rubber or styrene-butadiene rubber together with or instead of natural rubber.

[0029] Hereinafter, the details of the structure of the non-pneumatic tire 1 will be described. FIG. 1 is a side view of the non-pneumatic tire 1 viewed from the side in a direction parallel to the tire rotation axis (tire meridian), that is, in the direction along the front and back of the paper in FIG. 1. The non-pneumatic tire 1 shown in FIG. 1 is in an unloaded state. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. FIG. 3 is a partial perspective view of the non-pneumatic tire 1 looking obliquely at the portion shown in FIG. 2.

[0030] In FIGS. 1 and 3, C indicates the tire circumferential direction. In FIGS. 1 to 3, X indicates the tire radial direction. In FIGS. 2 and 3, Y indicates the tire width direction. In FIG. 1, the tire width direction Y is the front and back of the paper. In FIG. 2, E indicates the tire equatorial plane. In FIG. 2, the tire circumferential direction C is the front and back of the paper.

[0031] The tire circumferential direction C is the direction around the tire rotation axis and is the same as the 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 FIGS. 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 FIG. 2 is a plane orthogonal to the tire rotation axis and is located at the center of the tire width direction Y.

[0032] Note that the thicknesses of the inner annular portion 20 and the outer annular portion 30 are dimensions in the tire radial direction X. Also, the widths of the inner annular portion 20 and the outer annular portion 30 are dimensions in the tire width direction Y shown in FIG. 2.

[0033] The inner annular portion 20 is an annular portion along the tire circumferential direction C that constitutes the inner peripheral portion 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 disposed in the space on the inner peripheral side of the inner annular portion 20. The inner peripheral portion of the inner annular portion 20 is fitted and mounted on the outer peripheral portion of the rim of the tire wheel. When the inner annular portion 20 is mounted on the rim, the non-pneumatic tire 1 is mounted on the tire wheel. On the inner peripheral surface of the inner annular portion 20, a fitting portion composed of convex portions, grooves, etc. may be provided for fitting with the rim.

[0034] 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 satisfying the function of sufficiently transmitting the rotational force to the spokes 40 while achieving weight reduction and durability. The thickness of the inner annular portion 20 is not particularly limited, but for example, it is preferably 2% or more and 7% or less of the tire cross-sectional height H shown in FIG. 2, and more preferably 3% or more and 6% or less.

[0035] 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 use of the vehicle, and the like. For example, when assuming the replacement of 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 thereto.

[0036] The width of the inner annular portion 20 is appropriately determined according to the use of the vehicle on which the non-pneumatic tire 1 is mounted, the length of the axle, and the like. For example, when assuming the replacement of a general pneumatic tire, the width of the inner annular portion 20 may be a dimension of 100 mm or more and 300 mm or less, but is not limited thereto.

[0037] The outer annular portion 30 is an annular portion along the tire circumferential direction C that constitutes the outer peripheral portion of the non-pneumatic tire 1. The outer annular portion 30 is disposed concentrically with the inner annular portion 20 on the outer peripheral side of the inner annular portion 20. The thickness and width of the outer annular portion 30 are set to be constant in order to improve uniformity.

[0038] The outer annular portion 30 transmits the rotation of the inner annular portion 20 and the spoke 40 to the road surface via the tread 50. The thickness of the outer annular portion 30 is determined from the viewpoint of satisfying the function of sufficiently transmitting the rotational force from the spoke 40 to the road surface while achieving weight reduction and durability. The thickness of the outer annular portion 30 is not particularly limited, but is preferably, for example, 2% or more and 7% or less of the tire cross-sectional height H shown in FIG. 2, and more preferably 2% or more and 5% or less.

[0039] The inner diameter of the outer annular portion 30 is appropriately determined according to the dimensions of the rim of the tire wheel on which the non-pneumatic tire 1 is mounted, the use of the vehicle, and the like. For example, when assuming the replacement of a general pneumatic tire, the inner diameter of the outer annular portion 30 may be a dimension of 420 mm or more and 750 mm or less, but is not limited thereto.

[0040] The width of the outer annular portion 30 is appropriately determined according to the use of the vehicle to which the non-pneumatic tire 1 is mounted, etc. For example, when assuming the replacement of a general pneumatic tire, the width of the outer annular portion 30 may be dimensions such as 100 mm or more and 300 mm or less, but is not limited thereto.

[0041] 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. Each of the plurality of spokes 40 is independently arranged 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.

[0042] As shown in FIGS. 2 and 3, the plurality of spokes 40 of the present embodiment include a plurality of first spokes 41 and a plurality of second spokes 42. In either the first spoke 41 or the second spoke 42, the extending direction thereof is not parallel to the tire radial direction X when viewed in the direction along the tire circumferential direction C. The first spoke 41 is inclined toward one side in the tire axial direction, that is, the tire width direction Y. The second spoke 42 is inclined toward the side opposite to the first spoke 41. The first spoke 41 and the second spoke 42 are alternately arranged in the tire circumferential direction C.

[0043] Specifically, as shown in FIGS. 2 and 3, the first spoke 41 extends obliquely 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 spoke 42 extends obliquely 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.

[0044] The inclination angles of the first spoke 41 and the second spoke 42 are the same. Therefore, the first spoke 41 and the second spoke 42 adjacent to each other in the tire circumferential direction C are arranged in a substantially X shape when viewed from the direction along the tire circumferential direction C. As shown in FIG. 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 the angle θ is preferably, for example, 30° or more and 60° or less.

[0045] As shown in FIG. 2, each of the first spoke 41 and the second spoke 42 in a state viewed from the direction along the tire circumferential direction C has the same shape that is symmetric with respect to the tire equatorial plane E. Therefore, in the following, when there is no need to distinguish between the first spoke 41 and the second spoke 42 and they can be collectively described, the first spoke 41 and the second spoke 42 are collectively referred to as the spoke 40.

[0046] The spoke 40 is plate-shaped and extends obliquely at an angle of the angle θ as described above from the inner annular portion 20 toward the outer annular portion 30. As shown in FIG. 3, the spoke 40 has a plate thickness t along the tire circumferential direction that 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 spoke 40 is formed in a plate shape that extends along the plane of the tire radial direction X and the tire width direction Y. Here, the plate width w is, as also shown in FIG. 2, the dimension in the direction orthogonal to the inclination direction in which the spoke 40 extends when the spoke 40 is viewed from the direction along the tire circumferential direction C. In the present embodiment, the plate thickness t of all the spokes 40 is the same. Also, the plate width w of all the spokes 40 is the same.

[0047] Since the spoke 40 is in the shape of a long plate, even if the plate thickness t is made thin, the durability of the spoke 40 can be improved by setting the plate width w wide. Furthermore, by reducing the plate thickness t and increasing the number of the spokes 40, the interval between the spokes 40 adjacent to each other in the tire circumferential direction C can be reduced while maintaining the rigidity of the entire non-pneumatic tire 1. As a result, the contact pressure during tire rolling by the spokes 40 is dispersed, and the contact pressure can be reduced.

[0048] Note that although the spoke 40 is parallel to the tire radial direction X in side view, the spoke 40 may be arranged obliquely with respect to the tire radial direction X so as to intersect the tire radial direction X in side view.

[0049] As shown in FIGS. 2 and 3, 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. Each of the first outer connection portion 412 and the second outer connection portion 422 is an example of a connection portion of the spoke 40 connected to the outer annular portion 30 in the present embodiment.

[0050] As shown in FIG. 2, the first inner connection portion 411 of the first spoke 41 has a shape that spreads along the tire width direction Y as it approaches the inner annular portion 20. The side surface 411a on the tire width direction Y2 side of the first inner connection portion 411 extends while gently curving to the end portion 20b on the tire width direction Y2 side of the inner annular portion 20. The side surface 411b on the tire width direction Y1 side of the first inner connection portion 411 curves and extends toward the tire width direction Y1 side to the position of the tire equatorial plane E of the inner annular portion 20.

[0051] The first outer connection portion 412 of the first spoke 41 has the same shape as the first inner connection portion 411 and has a shape that spreads along the tire width direction as it approaches the outer annular portion 30. The side surface 412a on the tire width direction Y1 side of the first outer connection portion 412 extends while gently curving to the end portion 30a on the tire width direction Y1 side of the outer annular portion 30. The side surface 412b on the tire width direction Y2 side of the first outer connection portion 412 curves and extends toward the tire width direction Y2 side to the position of the tire equatorial plane E of the outer annular portion 30.

[0052] The first inner connection part 411 is provided in a region that is half of the inner annular part 20 on the tire width direction Y2 side. The first outer connection part 412 is provided in a region that is half of the outer annular part 30 on the tire width direction Y1 side.

[0053] As shown in FIG. 2, the second inner connection part 421 of the second spoke 42 has a shape that spreads along the tire width direction Y as it approaches the inner annular part 20. The side surface 421a on the tire width direction Y1 side of the second inner connection part 421 extends while gently curving up to the end part 20a on the tire width direction Y1 side of the inner annular part 20. The side surface 421b on the tire width direction Y2 side of the second inner connection part 421 curves and extends toward the tire width direction Y2 side up to the position of the tire equatorial plane E of the inner annular part 20.

[0054] The second outer connection part 422 of the second spoke 42 has the same shape as the second inner connection part 421, and has a shape that spreads along the tire width direction as it approaches the outer annular part 30. The side surface 422a on the tire width direction Y2 side of the second outer connection part 422 extends while gently curving up to the end part 30b on the tire width direction Y2 side of the outer annular part 30. The side surface 422b on the tire width direction Y1 side of the second outer connection part 422 curves and extends toward the tire width direction Y1 side up to the position of the tire equatorial plane E of the outer annular part 30.

[0055] The second inner connection part 421 is provided in a region that is half of the inner annular part 20 on the tire width direction Y1 side. The second outer connection part 422 is provided in a region that is half of the outer annular part 30 on the tire width direction Y2 side.

[0056] As described above, the plate thickness t of all the spokes 40 in the present embodiment is the same. The dimension of the plate thickness t is not particularly limited, but in order for the spoke 40 to sufficiently receive the rotational force from the inner annular part 20 and the outer annular part 30 and to be able to flexibly deform moderately when receiving a load, it is preferably 1 mm or more and 30 mm or less, and more preferably 5 mm or more and 25 mm or less.

[0057] As described above, the plate width w of all the spokes 40 in the present embodiment is the same. The plate width w of the spoke 40 is not particularly limited, but in order to sufficiently receive the rotational force from the inner annular portion 20 and the outer annular portion 30 and be able to flexibly deform appropriately when receiving a load, it is preferably 5 mm or more and 25 mm or less, and more preferably 10 mm or more and 20 mm or less. Further, from the viewpoint of being able to disperse the ground pressure while improving the durability, the plate width w is preferably 110% or more of the plate thickness t, and more preferably 115% or more.

[0058] The number of the spokes 40 is preferably 80 or more and 300 or less, and more preferably 100 or more and 200 or less, from the viewpoint of being able to sufficiently support the load from the vehicle, being able to achieve weight reduction, and improving both power transmission performance and durability.

[0059] 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. The tread 50 has a tread surface 51 that contacts the road surface on its outer peripheral surface. A tread pattern formed by a plurality of grooves and land portions is provided on the tread surface 51 of the tread 50 in the same manner as a conventional pneumatic tire.

[0060] Note that the tread 50 may have a structure in which a plurality of vulcanized rubber layers having different components and properties are laminated (for example, two layers or three layers).

[0061] Although the 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 appropriately modified within the scope of the gist of the present invention.

[0062] Note that the configuration of the embodiment of the present invention is as follows.

[0063] (1) A method for manufacturing a non-pneumatic tire provided with a support structure, the method including: injecting a thermosetting resin composition containing a polyol and a polyisocyanate into a mold; and thermosetting the thermosetting resin composition injected into the mold to obtain at least a part of the support structure, wherein the temperature of the thermosetting resin composition injected into the mold is 50°C or higher and 70°C or lower, and the temperature of the mold into which the thermosetting resin composition is injected is 15°C or higher and 40°C or lower lower than the temperature of the thermosetting resin composition injected into the mold.

[0064] (2) The method for manufacturing a non-pneumatic tire according to (1), wherein when thermosetting the thermosetting resin composition in an environment of 130°C or lower, the time required for the temperature of the mold to reach 100°C is 180 minutes or more.

[0065] (3) The method for manufacturing a non-pneumatic tire according to (1) or (2), wherein the polyol includes 1,4-butanediol and polytetramethylene glycol, and the polyisocyanate includes a urethane prepolymer.

[0066] (4) The support structure includes an inner annular portion, an outer annular portion disposed coaxially with the inner annular portion on the outer side in the tire radial direction of the inner annular portion, and a plurality of spokes connecting the inner annular portion and the outer annular portion and arranged along the tire circumferential direction, and at least a part of the support structure is at least one of the inner annular portion, the outer annular portion, and the spokes.

Examples

[0067] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the examples.

[0068] [Agent 1] After mixing Vibracure A250 (manufactured by LANXESS) as 1,4 - butanediol and PTMG1000 (manufactured by Mitsubishi Chemical) as polytetramethylene glycol in a predetermined mass ratio, a vacuum isothermal dryer DP63 (manufactured by Yamato Scientific) was used to perform vacuum degassing at a predetermined temperature for 2 hours to obtain the first agent.

[0069] [Second agent] Adiprene LFPE560 (manufactured by LANXESS) as a urethane prepolymer was vacuum degassed at a predetermined temperature for 2 hours using a vacuum isothermal dryer DP63 (manufactured by Yamato Scientific) to obtain the second agent.

[0070] [Examples 1 - 11, Comparative Examples 1 - 7] After mixing the first agent and the second agent, a magnetic stirrer KK - 5000W (manufactured by Kurashiki Boseki) as a planetary mixer was used to stir to obtain a thermosetting resin composition at a predetermined temperature (see Table 1). At this time, the isocyanate index of the thermosetting resin composition was set to 1.03. Next, after injecting the thermosetting resin composition into a mold, it was thermally cured at 130°C for 16 hours. At this time, using a thermocouple, the time required for the mold temperature to reach 100°C was measured. Next, after removing the mold, it was cooled to obtain a support structure (see Figures 1 - 3).

[0071] [Castability of the thermosetting resin composition] The thermosetting resin composition to be injected into the mold was visually confirmed to evaluate the castability. The criteria for judging the castability of the thermosetting resin composition are as follows. A: When the thermosetting resin composition can be injected into the mold B: When the thermosetting resin composition cannot be injected into the mold

[0072] [Sink marks on the support structure] The sink marks on the support structure were visually confirmed. The criteria for judging the sink marks on the support structure are as follows. A: When no sink marks are visible on the support structure B: When a small amount of sink marks are visible on the support structure C: When a large amount of sink marks are observed in the support structure

[0073] [Crack of spoke] The crack of the spoke was visually confirmed. The criteria for judging the crack of the spoke are as follows. A: When no crack is observed in the spoke B: When a crack is observed in the spoke

[0074] Table 1 shows the evaluation results of the castability of the thermosetting resin composition, the sink marks of the support structure, and the crack of the spoke. When the castability of the thermosetting resin composition is B, the evaluation of the sink marks of the support structure and the crack of the spoke is omitted.

Table 1

[0075] From Table 1, it can be seen that in Examples 1 to 11, the castability of the thermosetting resin composition is high, and the occurrence of sink marks on the support structure and cracks in the spokes is suppressed. On the other hand, in Comparative Examples 1 and 2, since T1 - T2 is 10.0 °C, sink marks on the support structure and cracks in the spokes are likely to occur. In Comparative Example 3, since T1 - T2 is 50.0 °C, the castability of the thermosetting resin composition is low. In Comparative Examples 4 and 5, since T1 - T2 is -3.0 °C and -13.5 °C, sink marks on the support structure and cracks in the spokes are likely to occur. In Comparative Examples 6 and 7, since T1 is 45.0 °C and 80.5 °C, the castability of the thermosetting resin composition is low.

Explanation of symbols

[0076] 1 Non-pneumatic tire 10 Support structure 20 Inner annular part 20a, 20b Ends 30 Outer annular part 30a, 30b Ends 40 Spoke 41 First spoke 42 Second spoke 411 First inner connection part 411a, 411b Sides 412 First outer connection part 412a, 412b Sides 421 Second inner connection part 421a, 421b Sides 422 Second outer connection part 422a, 422b Sides 50 Tread 51 Tread surface C Tire circumferential direction E Tire equatorial plane O Axis X Tire radial direction Y Tire width direction

Claims

1. A method for manufacturing a non-pneumatic tire having a support structure, comprising: injecting a thermosetting resin composition containing a polyol and a polyisocyanate into a mold; thermosetting the thermosetting resin composition injected into the mold to obtain at least a part of the support structure, wherein the temperature of the thermosetting resin composition injected into the mold is 50°C or higher and 70°C or lower, and the temperature of the mold into which the thermosetting resin composition is injected is 15°C or higher and 40°C or lower lower than the temperature of the thermosetting resin composition injected into the mold. A method for manufacturing a non-pneumatic tire.

2. When thermosetting the thermosetting resin composition in an environment of 130°C or lower, the time required for the temperature of the mold to reach 100°C is 180 minutes or more. The method for manufacturing a non-pneumatic tire according to claim 1.

3. The polyol includes 1,4-butanediol and polytetramethylene glycol, and the polyisocyanate includes a urethane prepolymer. The method for manufacturing a non-pneumatic tire according to claim 1 or 2.

4. The support structure includes an inner annular portion, an outer annular portion coaxially arranged with the inner annular portion on the outer side in the tire radial direction of the inner annular portion, and a plurality of spokes connecting the inner annular portion and the outer annular portion and arranged along the tire circumferential direction, and at least a part of the support structure is at least one of the inner annular portion, the outer annular portion, and the spokes. The method for manufacturing a non-pneumatic tire according to claim 1 or 2.

Images