Green tire and tire

Abstract

An object of the present invention is to provide a green tire capable of shortening the vulcanization time during retreading, and a tire manufactured using the green tire.SOLUTION: In the green tire of the present invention, the temperature increase ratio X1 of the high temperature increase ratio unvulcanized rubber layer is greater than the temperature increase ratio X2 of the one or more unvulcanized main body rubber layers. In the tire of the present invention, the temperature increase ratio Y1 of the high temperature increase ratio rubber layer is greater than the temperature increase ratio Y2 of the one or more main body rubber layers.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a green tire and a tire. [Background technology]

[0002] Conventionally, when vulcanizing and molding a tire using a rigid inner mold for tire vulcanization and molding, a technology has been proposed that can shorten the vulcanization time by heating the rigid inner mold and the unvulcanized tire formed on the outer surface of the rigid inner mold to a predetermined temperature in advance using microwaves (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-022010 Summary of the Invention [Problem to be solved by the invention]

[0004] Even during vulcanization of retreading, by using microwaves and setting the irradiation position, it is possible to preheat only the unvulcanized tread rubber.

[0005] However, during vulcanization, vulcanization tends to be slower in the radially inner region of the tire that is far from the mold, and even when preheating is performed using microwaves, there is still room for improvement in shortening the vulcanization time.

[0006] Therefore, an object of the present invention is to provide a green tire that can shorten the vulcanization time during retreading, and a tire manufactured using the green tire. [Means for solving the problem]

[0007] The following is a summary of the present invention. (1) A raw tire for retreading having unvulcanized tread rubber and a vulcanized case portion, The unvulcanized tread rubber comprises one or more unvulcanized main body rubber layers and a high-heat-rate unvulcanized rubber layer disposed radially inward of the one or more unvulcanized main body rubber layers, The high-heating-rate unvulcanized rubber extends in at least a portion of the tire width direction region, When the heating rate of unvulcanized rubber by microwaves is defined as the product of the dielectric constant and loss tangent of the unvulcanized rubber, The green tire is characterized in that the heating rate X1 of the high-heating-rate unvulcanized rubber layer is greater than the heating rate X2 of the one or more unvulcanized main body rubber layers.

[0008] Here, the "dielectric constant" of unvulcanized rubber is measured by the coaxial cable method. The "loss tangent" of unvulcanized rubber refers to the ratio (E" / E") of the dynamic loss modulus E" to the dynamic storage modulus E', obtained using a dynamic tensile viscoelasticity measuring instrument on a test piece of unvulcanized rubber 2 mm thick, 5 mm wide, and 20 mm long under the conditions of a temperature of 60°C, a frequency of 52 Hz, an initial strain of 2%, and a dynamic strain of 1%. In this specification, the term "microwave" refers to an electromagnetic wave with a frequency of 300 MHz to 300 GHz.

[0009] (2) The raw tire according to (1), wherein the heating rate X1 is equal to or greater than twice the heating rate X2.

[0010] (3) The raw tire according to (2), wherein the heating rate X1 is five times or more the heating rate X2.

[0011] (4) The green tire according to any one of (1) to (3), wherein the high-heating-rate unvulcanized rubber layer extends in a region in the tire width direction including between tread ends of the green tire.

[0012] (5) The green tire includes a shoulder land portion defined between a tread edge of the green tire and a portion corresponding to an outermost circumferential main groove, The green tire according to any one of (1) to (3), wherein the high-heating-rate unvulcanized rubber layer is disposed in at least a part of the tire width direction region where the shoulder land portion is located.

[0013] (6) When the midpoint in the tire width direction between the tire equatorial plane and the tread end of the raw tire is defined as a quarter point, The green tire according to any one of (1) to (3), wherein the high-heating-rate unvulcanized rubber layer extends only in the region between the quarter points in the tire width direction.

[0014] (7) The green tire according to any one of (1) to (3), wherein an end of the high-heating-rate unvulcanized rubber layer in the tire width direction is located 5 mm or more inward of a belt end in the tire width direction.

[0015] (8) The green tire according to any one of (1) to (7), wherein the high-heating-rate unvulcanized rubber layer has a thickness of 2 mm or less. Here, the "thickness of the high-heating-rate unvulcanized rubber layer" refers to the maximum thickness when measured in the tire radial direction.

[0016] (9) A retreaded tire having a tread rubber and a case portion, The tread rubber includes one or more main rubber layers and a high heating rate rubber layer disposed radially inward of the one or more main rubber layers, The high heating rate rubber extends in at least a portion of the tire width direction region, When the heating rate of vulcanized rubber by microwaves is defined as the product of the dielectric constant and loss tangent of the vulcanized rubber, A tire characterized in that the heating rate Y1 of the high heating rate rubber layer is greater than the heating rate Y2 of the one or more main rubber layers. Here, the "dielectric constant" of the vulcanized rubber is measured by the coaxial cable method. The "loss tangent" of vulcanized rubber refers to the ratio (E" / E") of the dynamic loss modulus E" to the dynamic storage modulus E', obtained using a dynamic tensile viscoelasticity measuring instrument on a test piece of vulcanized rubber 2 mm thick, 5 mm wide, and 20 mm long under the conditions of a temperature of 60°C, a frequency of 52 Hz, an initial strain of 2%, and a dynamic strain of 1%.

[0017] (10) The tire according to (9), wherein the heating rate Y1 is equal to or greater than twice the heating rate Y2.

[0018] (11) The tire according to (10), wherein the heating rate Y1 is five times or more the heating rate Y2.

[0019] (12) The tire according to any one of (9) to (11), wherein the high heating rate rubber layer extends in a region in the tire width direction including between tread ends of the tire. Here, the "tread edge" of a tire refers to the outermost point in the width direction of the contact patch that comes into contact with the road surface when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and subjected to the maximum load.

[0020] In this specification, the term "applicable rim" refers to the standard rim (Measuring Rim in the ETRTO Standards Manual, Design Rim in the TRA Year Book) for the applicable size that is described or will be described in the future, as an industrial standard in effect in the region where the tire is produced and used, such as the JATMA Year Book of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the Standards Manual of the European Tyre and Rim Technical Organization (ETRTO) in Europe, or the Year Book of the Tire and Rim Association, Inc. (TRA) in the United States. (In other words, the "rim" in the above "wheel" includes not only current sizes but also sizes that may be included in the above industrial standards in the future. An example of a "size to be described in the future" is the size listed under "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO.) However, in the case of a size not described in the above industrial standards, the term refers to a rim with a width that corresponds to the bead width of the tire. Furthermore, "specified internal pressure" refers to the air pressure (maximum air pressure) that corresponds to the maximum load capacity of a single wheel for the applicable size and ply rating as specified in the above JATMA etc., and in the case of sizes not specified in the above industry standards, "specified internal pressure" refers to the air pressure (maximum air pressure) that corresponds to the maximum load capacity specified for each vehicle on which the tire is fitted. Furthermore, the "maximum load" refers to the load corresponding to the maximum load capacity.

[0021] (13) The tire includes a shoulder land portion defined between a tread edge of the tire and an outermost circumferential main groove, The tire according to any one of (9) to (11), wherein the high heating rate rubber layer is disposed in at least a part of the tire width direction region where the shoulder land portion is located.

[0022] (14) When the midpoint in the tire width direction between the tire equatorial plane and the tread end of the tire is defined as a quarter point, The tire according to any one of (9) to (11), wherein the high heating rate rubber layer extends only in the region between the quarter points in the tire width direction. Here, the "1 / 4 point" refers to the midpoint when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and no load is applied.

[0023] (15) The tire according to any one of (9) to (11), wherein an end of the high heating rate rubber layer in the tire width direction is located 5 mm or more inward of a belt end in the tire width direction.

[0024] (16) The tire according to any one of (9) to (11), wherein the high heating rate rubber layer has a thickness of 2 mm or less. Here, the "thickness of the high heating rate rubber layer" in a tire refers to the maximum thickness of the high heating rate rubber layer when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and under no load, and measured in the radial direction of the tire. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a green tire that can shorten the vulcanization time during retreading, and a tire manufactured using the green tire. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a schematic partial cross-sectional view in the width direction of a raw tire according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic partial cross-sectional view in the width direction of a raw tire according to a first modified example. [Figure 3] FIG. 10 is a schematic partial cross-sectional view in the width direction of a green tire according to a second modified example. [Figure 4] 1 is a schematic partial cross-sectional view in the width direction of a tire according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <Raw tires> 1 is a schematic partial cross-sectional view in the width direction of a green tire according to one embodiment of the present invention. This green tire 1 is a green tire for retreading, including unvulcanized tread rubber 2 and a vulcanized case portion 3.

[0028] The case portion 3 includes a pair of bead portions (not shown) and a sidewall portion (not shown) connected to the pair of bead portions. The carcass 7 extends toroidally between the pair of bead portions. A belt 6 consisting of one or more belt layers 6a, 6b (two layers in the illustrated example) is disposed on the radially outer side of the carcass 7. The configuration of the case portion 3 is not particularly limited. For example, a bead core may be embedded in the bead portion, or the tire may be coreless. The number of carcass plies is not particularly limited as long as it is one or more. The carcass structure may also have a carcass folded portion, or may be wrapped around a bead core. The belt structure is also not particularly limited. The number of belt layers, the width of the belt layer, the inclination angle with respect to the circumferential direction, and the like may vary. In addition, various materials may be used for the respective members.

[0029] The unvulcanized tread rubber 2 comprises one or more unvulcanized main rubber layers 4 and a high heating rate unvulcanized rubber layer 5 arranged radially inward of the one or more unvulcanized main rubber layers 4.

[0030] In the illustrated example, the one or more unvulcanized main rubber layers 4 are made up of two unvulcanized main rubber layers 4a, 4b. The two unvulcanized main rubber layers 4a, 4b have a so-called cap-and-base structure, with the unvulcanized main rubber layer 4a on the outer side in the tire radial direction being the cap rubber layer and the unvulcanized main rubber layer 4b on the inner side in the tire radial direction being the base rubber layer. In the illustrated example, the unvulcanized main rubber layer 4 has two layers, but it may also have one layer, or three or more layers.

[0031] The loss tangent tanδ1 of the unvulcanized main rubber layer 4a (cap rubber layer) is preferably larger than the loss tangent tanδ2 of the unvulcanized main rubber layer 4b (base rubber layer). This is because excessive heat generation in the base rubber layer can be suppressed while the grip performance of the cap rubber layer arranged on the radially outer side of the tire is exhibited. The loss tangent tanδ1 of the unvulcanized main rubber layer 4a (cap rubber layer) is not particularly limited, but is preferably 0.01 or more and 0.08 or less. The loss tangent tanδ2 of the unvulcanized main rubber layer 4b (base rubber layer) is not particularly limited, but is preferably 0.13 or more and 0.6 or less. The dielectric constant of the unvulcanized main rubber layer 4a (cap rubber layer) is not particularly limited, but is preferably 2.0 (F / m) or more and 8.0 (F / m) or less. The dielectric constant of the unvulcanized main rubber layer 4b (base rubber layer) is not particularly limited, but is preferably 10 (F / m) or more and 60 (F / m) or less.

[0032] The high-heating-rate unvulcanized rubber 5 extends in at least a part of the tire width direction region. In the illustrated example, the high-heating-rate unvulcanized rubber layer 5 extends in the tire width direction region including the region between the tread ends of the raw tire 1 (extending to the entire region between the tread ends and to regions on both outer sides in the tire width direction).

[0033] Here, the heating rate of unvulcanized rubber by microwaves is defined as the product of the dielectric constant and loss tangent of the unvulcanized rubber. At this time, in the raw tire 1 of this embodiment, the heating rate X1 of the high-heating-rate unvulcanized rubber layer 5 is larger than the heating rate X2 of one or more unvulcanized main rubber layers 4. In particular, in this example, the loss tangent of the cap rubber layer is larger than the loss tangent of the base rubber layer, and the heating rate of the cap rubber layer is larger than the heating rate of the base rubber layer, but the heating rate X1 of the high-heating-rate unvulcanized rubber layer 5 is larger than the heating rate of the cap rubber layer. The following describes the effects of the green tire 1 of this embodiment.

[0034] In the raw tire 1 of this embodiment, a high-heating-rate unvulcanized rubber layer 5 is disposed radially inward of one or more unvulcanized main body rubber layers 4, and the heating rate X1 of the high-heating-rate unvulcanized rubber layer 5 is greater than the heating rate X2 of the one or more unvulcanized main body rubber layers 4. The high-heating-rate unvulcanized rubber 5 extends over at least a portion of the tire width direction region. In the tread rubber 2, the region on the inner side in the tire radial direction has a tendency to be vulcanized slowly because it is far from the mold. In contrast to this, in this embodiment, the high-heating-rate unvulcanized rubber layer 5 is arranged on the inner side in the tire radial direction, and therefore, by preheating the tread rubber 2 with microwaves, the high-heating-rate unvulcanized rubber layer 5, which has a higher heating rate X1 (relatively higher than the heating rate X2), is selectively heated in particular, thereby shortening the vulcanization time of the region that was previously the slowest vulcanization location, and also shortening the vulcanization time of the entire vulcanization process during retreading. As described above, according to the green tire 1 of this embodiment, the vulcanization time can be shortened during retreading.

[0035] The heating rate X1 is preferably at least twice the heating rate X2. This is because the vulcanization time during retreading can be further shortened. For the same reason, the heating rate X1 is more preferably at least five times the heating rate X2, even more preferably at least 10 times, and particularly preferably at least 12 times. In the case of a cap-and-base structure, the heating rate X1 is preferably at least two times the heating rate of the cap rubber layer, more preferably at least five times, even more preferably at least 10 times, and particularly preferably at least 12 times.

[0036] Although there are no particular limitations on how to adjust the heating rate X1 of the high heating rate unvulcanized rubber layer 5 to fall within the above ranges, the heating rate can be adjusted by appropriately adjusting the proportion of carbon black.

[0037] 1, it is preferable that the high-heating-rate unvulcanized rubber layer 5 extends in a region in the tire width direction including between the tread ends of the raw tire 1. This is because the above-mentioned effects can be obtained in a wide region in the tire width direction, and a further reduction in the vulcanization time can be expected.

[0038] FIG. 2 is a schematic widthwise partial cross-sectional view of a raw tire according to a first modified example. It is also preferable that the raw tire 1 has a shoulder land portion defined between the tread edge of the raw tire 1 and a portion corresponding to the outermost circumferential main groove 8 (the raw tire 1 has no circumferential main grooves yet formed therein), and that the high-heating-rate unvulcanized rubber layer 5 is disposed in at least a portion of the tire widthwise region where the shoulder land portion is located. The shoulder land portion tends to have the thickest rubber gauge among the land portions and may be the slowest location for vulcanization. Therefore, disposing the high-heating-rate unvulcanized rubber layer 5 with a high heating rate in such a location may be effective in further shortening the vulcanization time. More preferably, the high-heating-rate unvulcanized rubber layer 5 is disposed over the entire tire widthwise region where the shoulder land portion is located.

[0039] 3 is a schematic widthwise partial cross-sectional view of a raw tire according to a second modified example. When the midpoint in the tire width direction between the tire equatorial plane and the tread end of the raw tire 1 is defined as a quarter point (point P), it is also preferable that the high-heating-rate unvulcanized rubber layer 5 extends only in the tire widthwise region between the quarter points. Belts usually extend further outward in the tire width direction than the quarter point (the belt end is located further outward in the tire width direction than the quarter point). In this case, by setting the extension range of the high-heating-rate unvulcanized rubber layer 5 as described above, it is possible to ensure a distance between the high-heating-rate unvulcanized rubber layer 5 (end) and the belt end, and to prevent peeling of the belt coating rubber at the belt end due to microwave heating.

[0040] The end of the high-heating-rate unvulcanized rubber layer 5 in the tire width direction is preferably located 5 mm or more inward from the belt end in the tire width direction. By setting the extension width of the high-heating-rate unvulcanized rubber layer 5 as described above, the distance between the (end of) the high-heating-rate unvulcanized rubber layer 5 and the belt end can be secured, and peeling of the belt coating rubber at the belt end due to heating by microwaves can be suppressed.

[0041] The thickness of the high-heat-rate unvulcanized rubber layer 5 is preferably 2 mm or less, because this allows the basic tire performance to be mainly borne by the (vulcanized) unvulcanized main rubber layer 4, and for example, even if the loss tangent of the high-heat-rate unvulcanized rubber layer 5 is large, low heat generation and low rolling resistance can be achieved for the entire tire.

[0042] <Tires> 4 is a schematic partial cross-sectional view in the width direction of a tire according to one embodiment of the present invention. The tire 10 is a retreaded tire including a tread rubber 20 and a case portion 30. The tire 10 of this embodiment can be obtained by vulcanizing the unvulcanized tread rubber 2 of the raw tire 1 of the above embodiment.

[0043] The case portion 30 includes a pair of bead portions (not shown) and a sidewall portion (not shown) connected to the pair of bead portions. The carcass 70 extends toroidally between the pair of bead portions. A belt 60 consisting of one or more belt layers 60a, 60b (two layers in the illustrated example) is disposed on the radially outer side of the carcass 70. The configuration of the case portion 30 is not particularly limited. For example, a bead core may be embedded in the bead portion, or the tire may be coreless. The number of carcass plies is not particularly limited as long as it is one or more. The carcass structure may also have a carcass folded portion, or may be wrapped around a bead core. The belt structure is also not particularly limited. The number of belt layers, the width of the belt layer, the inclination angle with respect to the circumferential direction, and the like may vary. In addition, various materials may be used for the respective components.

[0044] The tread rubber 20 includes one or more main rubber layers 40 and a high heating rate rubber layer 50 arranged inside the one or more main rubber layers 40 in the tire radial direction.

[0045] In the illustrated example, the one or more main rubber layers 40 are made up of two main rubber layers 40a, 40b. The two main rubber layers 40a, 40b have a so-called cap and base structure, with the main rubber layer 40a on the outer side in the tire radial direction being the cap rubber layer and the main rubber layer 40b on the inner side in the tire radial direction being the base rubber layer. In the illustrated example, the main rubber layer 4 is made up of two layers, but it may also be made up of one layer, or three or more layers.

[0046] The loss tangent tanδ3 of the main rubber layer 40a (cap rubber layer) is preferably larger than the loss tangent tanδ4 of the main rubber layer 40b (base rubber layer). This is because excessive heat generation in the base rubber layer can be suppressed while maintaining the grip performance of the cap rubber layer arranged on the radially outer side of the tire. The loss tangent tanδ3 of the main rubber layer 40a (cap rubber layer) is not particularly limited, but is preferably 0.01 or greater and 0.08 or less. The loss tangent tanδ4 of the main rubber layer 40b (base rubber layer) is not particularly limited, but is preferably 0.13 or greater and 0.6 or less. The dielectric constant of the main rubber layer 40a (cap rubber layer) is not particularly limited, but is preferably 2.0 (F / m) or more and 8.0 (F / m) or less, and the dielectric constant of the main rubber layer 40b (base rubber layer) is not particularly limited, but is preferably 10 (F / m) or more and 60 (F / m) or less.

[0047] The high heating rate rubber 50 extends in at least a part of the tire width direction region. In the illustrated example, the high heating rate rubber layer 50 extends in the tire width direction region including the region between the tread ends of the tire 10 (extending to the entire region between the tread ends and to regions on both outer sides in the tire width direction).

[0048] Here, the heating rate of vulcanized rubber by microwaves is defined as the product of the dielectric constant and loss tangent of the vulcanized rubber. At this time, in the tire 10 of this embodiment, the heating rate Y1 of the high heating rate rubber layer 50 is greater than the heating rate Y2 of the one or more main rubber layers 40. In particular, in this example, the loss tangent of the cap rubber layer is greater than the loss tangent of the base rubber layer, and the heating rate of the cap rubber layer is greater than the heating rate of the base rubber layer, but the heating rate Y1 of the high heating rate rubber layer 50 is greater than the heating rate of the cap rubber layer. The effects of the tire 10 of this embodiment will be described below.

[0049] As described above, the tire 10 of this embodiment is obtained by vulcanizing the unvulcanized tread rubber 2 of the raw tire 1 of the above embodiment. Furthermore, a high-heating-rate rubber layer 50 is disposed radially inward of one or more main rubber layers 40, and the heating rate Y1 of the high-heating-rate rubber layer 50 is greater than the heating rate Y2 of the one or more main rubber layers 40. The high-heating-rate rubber 50 extends over at least a portion of the tire width direction region. Therefore, when vulcanizing the raw tire 1 to obtain the tire 10 having the above-described configuration, the vulcanization time during retreading can be shortened by preheating the tread rubber 2 with microwaves. As described above, according to the tire 10 of the present embodiment, when such a tire 10 is to be manufactured by retreading, the vulcanization time in the retreading can be shortened.

[0050] For the same reasons as those explained in the embodiment of the raw tire 1, the heating rate Y1 is preferably at least twice the heating rate Y2, more preferably at least five times, even more preferably at least 10 times, and particularly preferably at least 12 times. In the case of a cap-and-base structure, the heating rate Y1 is preferably at least twice the heating rate of the cap rubber layer, more preferably at least five times, even more preferably at least 10 times, and particularly preferably at least 12 times.

[0051] Although there are no particular limitations on how to adjust the heating rate Y1 of the high heating rate rubber layer 50 to fall within the above ranges, the heating rate can be adjusted by appropriately adjusting the ratio of carbon black.

[0052] 4, it is preferable that the high heating rate rubber layer 50 extends in a region in the tire width direction including between the tread ends of the tire 10. This is because the above-mentioned effects can be obtained in a wide region in the tire width direction, and a further reduction in vulcanization time can be expected.

[0053] It is also preferable that the tire 10 has a shoulder land portion defined between the tread edge and the outermost circumferential main groove of the tire 10, and that the high heating rate rubber layer 50 be disposed in at least a part of the tire width direction region where the shoulder land portion is located. The shoulder land portion tends to have the thickest rubber gauge among the land portions and may be the slowest part to vulcanize, so disposing the high heating rate rubber layer 50 with a high heating rate in such a part may be effective in further shortening the vulcanization time. More preferably, the high heating rate rubber layer 50 is disposed over the entire tire width direction region where the shoulder land portion is located.

[0054] When the midpoint in the tire width direction between the tire equatorial plane and the tread end of the tire 10 is defined as a quarter point (point P), it is also preferable that the high heating rate rubber layer 50 extends only in the tire width direction region between the quarter points. The belt usually extends further outward in the tire width direction than the quarter point (the belt end is located further outward in the tire width direction than the quarter point), and in this case, by setting the extension range of the high heating rate rubber layer 50 as described above, the distance between (the end of) the high heating rate rubber layer 50 and the belt end can be secured, and peeling of the belt coating rubber at the belt end due to heating by microwaves can be suppressed.

[0055] The end of the high-heating-rate rubber layer 50 in the tire width direction is preferably located 5 mm or more inward from the belt end in the tire width direction. By setting the extension width of the high-heating-rate rubber layer 50 as described above, it is possible to ensure a distance between the (end of) the high-heating-rate rubber layer 50 and the belt end, and to prevent peeling of the belt coating rubber at the belt end due to heating by microwaves.

[0056] The thickness of the high-heating-rate rubber layer 50 is preferably 2 mm or less, because this allows the main rubber layer 40 to bear the basic tire performance, and for example, even if the loss tangent of the high-heating-rate rubber layer 50 is large, low heat generation and low rolling resistance can be achieved for the entire tire.

[0057] [Contribution to the United Nations-led Sustainable Development Goals (SDGs)] The SDGs have been proposed to realize a sustainable society. One embodiment of the present invention is expected to be a technology that contributes to goals such as "No. 12: Responsible Consumption and Production" and "No. 13: Take concrete action against climate change." [Explanation of symbols]

[0058] 1: Raw tires, 2: Tread rubber, 3: Case part, 4: Unvulcanized main rubber layer, 5: High heating rate unvulcanized rubber layer, 6: Belt, 7: Carcass, 8: outermost circumferential main groove corresponding portion, 10: Tires, 20: Tread rubber, 30: Case part, 40: Main body rubber layer, 50: High heating rate rubber layer, 60: Belt, 70: Carcass

Claims

1. A raw tire for retreading having an unvulcanized tread rubber and a vulcanized case portion, The unvulcanized tread rubber includes one or more unvulcanized main body rubber layers and a high-heat-rate unvulcanized rubber layer disposed radially inward of the one or more unvulcanized main body rubber layers, The high-heating-rate unvulcanized rubber extends in at least a portion of the tire width direction region, When the heating rate of unvulcanized rubber by microwaves is defined as the product of the dielectric constant and loss tangent of the unvulcanized rubber, The raw tire is characterized in that the heating rate X1 of the high-heating-rate unvulcanized rubber layer is greater than the heating rate X2 of the one or more unvulcanized main rubber layers.

2. The raw tire according to claim 1 , wherein the heating rate X1 is equal to or greater than twice the heating rate X2.

3. The raw tire according to claim 2 , wherein the heating rate X1 is five times or more the heating rate X2.

4. The green tire according to claim 1 or 2, wherein the high-heating-rate unvulcanized rubber layer extends in a region in the tire width direction including between tread ends of the green tire.

5. the raw tire includes a shoulder land portion defined between a tread end of the raw tire and a portion corresponding to an outermost circumferential main groove, The raw tire according to claim 1 or 2, wherein the high-heating-rate unvulcanized rubber layer is disposed in at least a part of a region in the tire width direction where the shoulder land portion is located.

6. When the midpoint in the tire width direction between the tire equatorial plane and the tread end of the raw tire is defined as a quarter point, The green tire according to claim 1 or 2, wherein the high-heating-rate unvulcanized rubber layer extends only in a region between the quarter points in the tire width direction.

7. The raw tire according to claim 1 or 2, wherein an end in the tire width direction of the high-heating-rate unvulcanized rubber layer is located 5 mm or more inward in the tire width direction from an end of the belt.

8. 3. The raw tire according to claim 1, wherein the high-heating-rate unvulcanized rubber layer has a thickness of 2 mm or less.

9. A retreaded tire having a tread rubber and a case portion, The tread rubber includes one or more main rubber layers and a high heating rate rubber layer disposed radially inward of the one or more main rubber layers, The high heating rate rubber extends in at least a portion of the tire width direction region, When the heating rate of vulcanized rubber by microwaves is defined as the product of the dielectric constant and loss tangent of the vulcanized rubber, A tire characterized in that the heating rate Y1 of the high heating rate rubber layer is greater than the heating rate Y2 of the one or more main rubber layers.

10. The tire according to claim 9, wherein the heating rate Y1 is equal to or greater than twice the heating rate Y2.

11. The tire according to claim 10, wherein the heating rate Y1 is equal to or greater than five times the heating rate Y2.

12. The tire according to claim 9 or 10, wherein the high heating rate rubber layer extends in a region in the tire width direction including between tread ends of the tire.

13. The tire includes a shoulder land portion defined between a tread edge and an outermost circumferential main groove of the tire, The tire according to claim 9 or 10, wherein the high heating rate rubber layer is disposed in at least a part of a tire width direction region where the shoulder land portion is located.

14. When the midpoint in the tire width direction between the tire equatorial plane and the tread end of the tire is defined as a quarter point, The tire according to claim 9 or 10, wherein the high heating rate rubber layer extends only in a region between the quarter points in the tire width direction.

15. The tire according to claim 9 or 10, wherein an end of the high heating rate rubber layer in the tire width direction is located 5 mm or more inward of a belt end in the tire width direction.

16. The tire according to claim 9 or 10, wherein the high heating rate rubber layer has a thickness of 2 mm or less.

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