Pneumatic tire and manufacturing method thereof

Abstract

To provide a pneumatic tire provided with an inner liner excellent in air barrier properties and a method for manufacturing the same.SOLUTION: A pneumatic tire includes an inner liner formed by a spirally wound rubber ribbon. The rubber ribbon includes a first rubber layer forming an innermost surface of the tire and a second rubber layer disposed outside the first rubber layer in a tire radial direction. The first rubber layer protrudes in a ribbon longitudinal direction more than at least one of a leading edge and a trailing edge of the second rubber layer in a ribbon longitudinal direction. A method for manufacturing the pneumatic tire includes steps of molding the rubber ribbon and molding an inner liner rubber. In the step of molding the rubber ribbon, the first rubber layer is made to protrude in the ribbon longitudinal direction more than at least one of the leading edge and trailing edge of the second rubber layer in the ribbon longitudinal direction.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a pneumatic tire and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 discloses a pneumatic tire with an inner liner formed of a spirally wound rubber ribbon. The cross section of the rubber ribbon is divided into two layers: a first rubber layer made of a first rubber with high air barrier properties and a second rubber layer made of a second rubber with lower air barrier properties than the first rubber. The first rubber layer is disposed on the innermost tire surface of the inner liner.

[0003] From the viewpoint of ensuring the air barrier properties of the inner liner, it is important not to expose the second rubber layer on the innermost tire surface of the inner liner. Therefore, the present inventors have focused on the fact that no effort has been made to prevent the second rubber layer from being exposed at the ends (leading end or trailing end) of the rubber ribbon in the ribbon longitudinal direction, and have conceived of a pneumatic tire and a manufacturing method thereof according to the present disclosure described below in order to form an inner liner with excellent air barrier properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 7420 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a pneumatic tire including an inner liner with excellent air barrier properties, and a method for manufacturing the same. [Means for solving the problem]

[0006] The pneumatic tire of the present disclosure includes an inner liner formed of a spirally wound rubber ribbon, the rubber ribbon including a first rubber layer forming the innermost tire surface of the rubber ribbon, and a second rubber layer arranged radially outward of the first rubber layer, the first rubber layer protruding in the ribbon longitudinal direction beyond at least one of a leading end and a trailing end of the second rubber layer in the ribbon longitudinal direction.

[0007] The manufacturing method of the pneumatic tire disclosed herein includes a step of molding a rubber ribbon including a first rubber layer forming the innermost surface of the tire and a second rubber layer arranged radially outward of the first rubber layer, and a step of spirally winding the rubber ribbon to form an inner liner rubber, wherein the step of molding the rubber ribbon causes the first rubber layer to protrude in the ribbon longitudinal direction beyond at least one of the leading end and trailing end of the second rubber layer in the ribbon longitudinal direction. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a meridian cross-sectional view of a pneumatic tire according to an embodiment; [Diagram 2] Top view of rubber ribbon [Figure 3A] Cross-sectional view of line III-III in Figure 2 [Figure 3B] Cross-sectional view showing a modified example of the rubber ribbon [Figure 3C] FIG. 11 is a cross-sectional view showing a further modified example of the rubber ribbon. [Figure 4] Cross-sectional view of line IV-IV in Figure 2 [Diagram 5] A plan view showing the state in which the rubber ribbon is wound around the forming drum. [Figure 6] Enlarged cross-sectional view of the main part taken along the line VI-VI in Figure 5 [Figure 7] Enlarged cross-sectional view of the main part taken along line VII-VII in FIG. [Figure 8] Schematic diagram of extrusion molding device [Figure 9] Front view of extrusion molding device [Figure 10] Cross-sectional view of line XX in Figure 9 [Figure 11]Cross-sectional view for explaining a method for forming a rubber ribbon DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] First, one embodiment of a pneumatic tire will be described with reference to Fig. 1. Note that in each of the drawings (Figs. 1 to 11), the dimensional ratios in the drawings do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match either.

[0010] In FIG. 1, a first direction D1 is a tire axial direction D1 that is parallel to the tire rotation axis of a pneumatic tire (hereinafter also simply referred to as "tire") 1, and a second direction D2 is a tire radial direction D2 that is the diameter direction of the tire 1.

[0011] In the tire axial direction D1, the inner side is the side closer to the tire equatorial plane S1, and the outer side is the side farther from the tire equatorial plane S1. In addition, in the tire radial direction D2, the inner side is the side closer to the tire rotation axis, and the outer side is the side farther from the tire rotation axis. The tire equatorial plane S1 is a plane that is perpendicular to the tire rotation axis and is located at the center of the tire axial direction D1 of the tire 1, and the tire meridian plane is a plane that includes the tire rotation axis and is perpendicular to the tire equatorial plane S1.

[0012] 1, a tire 1 according to this embodiment includes a pair of beads 11, 11, sidewalls 12, 12 extending outward in the tire radial direction D2 from each bead 11, and a tread 13 continuing to outer ends of the pair of sidewalls 12, 12 in the tire radial direction D2. The tire 1 is mounted on a rim (not shown).

[0013] The tire 1 includes a carcass ply 14 extending between a pair of beads 11, 11, and an inner liner 15 disposed on the inside of the carcass ply 14 in the tire radial direction D2. The carcass ply 14 and the inner liner 15 are disposed along the inner circumference of the tire 1 across the pair of beads 11, 11, the sidewall 12, and the tread 13.

[0014] The inner liner 15 is disposed on the innermost surface of the tire, and faces the internal space filled with air of the tire 1. The inner liner 15 is in close contact with the tire inner circumferential side of the carcass ply 14, and no other members are interposed between the inner liner 15 and the carcass ply 14. The inner liner 15 is formed of an inner liner rubber 500 (see FIG. 5, etc.) formed by a so-called ribbon method in which a rubber ribbon 100 described later is spirally wound around a forming drum 400.

[0015] [Rubber ribbon and inner liner rubber] Next, an example of the rubber ribbon 100 and the inner liner rubber 500 will be described with reference to FIGS.

[0016] As shown in Fig. 2 and Fig. 3A, the rubber ribbon 100 is continuously discharged by an extrusion molding device 20 described later and formed into a long plate shape. The thickness of the rubber ribbon 100 gradually decreases from the center toward the side end 100a in the ribbon width direction D5. As a result, when the rubber ribbon 100 is spirally wound around a molding drum 400 as shown in Fig. 5 and Fig. 6, the thickness of the inner liner rubber 500 formed by the rubber ribbon 100 can be made closer to uniform. In this embodiment, the rubber ribbon 100 is formed into a substantially triangular cross section as shown in Fig. 3A, but is not limited thereto. For example, the rubber ribbon 100 may be formed into a substantially trapezoidal cross section or a substantially crescent cross section.

[0017] The rubber ribbon 100 includes a first rubber layer 101 disposed on one side (first ribbon thickness direction D41) of the ribbon thickness direction D4, and a second rubber layer 102 disposed on the other side (second ribbon thickness direction D42) of the first rubber layer 101 in the ribbon thickness direction D4. One side of the ribbon thickness direction D4 corresponds to the inner side of the tire radial direction D2, and the other side of the ribbon thickness direction D4 corresponds to the outer side of the tire radial direction D2. The first rubber layer 101 forms the innermost surface of the tire when the tire 1 in FIG. 1 is molded, and the second rubber layer 102 is disposed on the outer side of the first rubber layer 101 in the tire radial direction D2.

[0018] The first rubber layer 101 is formed of a first rubber, and the second rubber layer 102 is formed of a second rubber different from the first rubber. In this embodiment, the first rubber is butyl rubber having excellent air barrier properties. The second rubber is squeegee rubber that prevents the carcass ply 14 in FIG. 1 from being exposed to the innermost surface of the tire when the unvulcanized tire is expanded by the bladder. The squeegee rubber is a rubber material that is harder than butyl rubber.

[0019] It is preferable that the thickness T1 of the first rubber layer 101 in the ribbon thickness direction D4 be 1.5 mm or more, from the viewpoint of preventing the second rubber layer 102 from being exposed on the forming drum 400 side when the rubber ribbon 100 is spirally wound around the forming drum 400 (see Figure 6).

[0020] The side end 102a of the second rubber layer 102 in the ribbon width direction D5 is covered by the first rubber layer 101. As a result, as shown in FIG. 5 and FIG. 6, when the rubber ribbon 100 is spirally wound around the forming drum 400, the second rubber layer 102 can be prevented from being exposed to the forming drum 400 side at the interface between the rubber ribbons 100 adjacent to each other in the ribbon width direction D5. As shown in FIG. 3A, the second rubber layer 102 is exposed at the center of the rubber ribbon 100 in the ribbon width direction D5. In this embodiment, the first rubber layer 101 covers the second rubber layer 102 from the side end 102a of the second rubber layer 102 to the second ribbon thickness direction D42 side, but is not limited to this. For example, the first rubber layer 101 may be configured to cover up to the side end 102a of the second rubber layer 102 as shown in FIG. 3B.

[0021] In this embodiment, the second rubber layer 102 has a pair of side ends 102a, 102a covered by the first rubber layer 101 as shown in FIG. 3A, but is not limited thereto. For example, the second rubber layer 102 may have a first side end 102d covered by the first rubber layer 101 and a second side end 102e not covered by the first rubber layer 101 as shown in FIG. 3C. In such a configuration, it is preferable to wind the rubber ribbon 100 around the forming drum 400 so that the second side end 102e becomes the side end 500a on the winding start side of the inner liner rubber 500 in FIG. 5. Then, it is preferable to fold back the side end 500a on the winding start side toward the second ribbon thickness direction D42 side to form the inner liner 15 in FIG. 1. This makes it possible to suppress exposure of the second rubber layer 102 on the innermost surface of the tire even in the configuration of FIG. 3C.

[0022] As shown in Figures 3A and 6, it is preferable that the side end 100a of the rubber ribbon 100 has a pointed shape toward the outside in the ribbon width direction D5, in order to prevent air from entering the areas where the rubber ribbons 100 overlap when forming the inner liner rubber 500.

[0023] As shown in Fig. 4, the first rubber layer 101 protrudes in the ribbon longitudinal direction D3 from at least one of the leading end 102b and the trailing end 102c of the second rubber layer 102 in the ribbon longitudinal direction D3. As shown in Figs. 4 and 5, the leading end 102b of the second rubber layer 102 is located at the leading end 100b of the rubber ribbon 100 that is first wound around the forming drum 400, and the trailing end 102c of the second rubber layer 102 is located at the trailing end 100c of the rubber ribbon 100 that is last wound around the forming drum 400. In this embodiment, the first rubber layer 101 protrudes in the ribbon longitudinal direction D3 from each of the leading end 102b and the trailing end 102c of the second rubber layer 102 in the ribbon longitudinal direction D3.

[0024] The length L1 of the first rubber layer 101 protruding from the front end 102b of the second rubber layer 102 is preferably 1.5 mm or more from the viewpoint of preventing the second rubber layer 102 from being exposed to the forming drum 400 side when the rubber ribbon 100 is spirally wound around the forming drum 400. The length L2 of the first rubber layer 101 protruding from the rear end 102c is also the same.

[0025] In order to prevent the second rubber layer 102 from being exposed to the forming drum 400 side when the rubber ribbon 100 is spirally wound around the forming drum 400, it is preferable that the leading end 102b and / or the trailing end 102c of the second rubber layer 102 are covered by the first rubber layer 101.

[0026] As shown in Figures 4 and 7, the tip 100b of the rubber ribbon 100 preferably has a pointed shape in the ribbon longitudinal direction D3 in order to prevent air from entering the area where the rubber ribbons 100 overlap when the inner liner rubber 500 is formed.

[0027] As shown in Figures 5 and 6, the inner liner rubber 500 is formed by winding the rubber ribbon 100 in a spiral shape (e.g., shifted by half a pitch) around the forming drum 400. By forming the inner liner rubber 500 using the rubber ribbon 100 in which the rubber layers 101, 102 are integrated, it is possible to reduce the time required to form the inner liner rubber 500 and reduce errors in attaching the first rubber layer 101 and the second rubber layer 102, compared to when the rubber layers 101, 102 are wound separately. In addition, it becomes easier to adjust the ratio of the rubber layers 101, 102 in the inner liner rubber 500, which makes it possible to reduce the weight of the tire 1 and improve tire performance such as rolling resistance.

[0028] If the side end portions 102a, 102a of the second rubber layer 102 in the rubber ribbon 100 were exposed, the second rubber layer 102 would be exposed on the innermost tire surface of the inner liner 15 (the surface of the inner liner rubber 500 facing the molding drum 400), and there is a risk that air inside the tire may pass through the exposed portion of the second rubber layer 102. For this reason, it is necessary to suppress exposure of the second rubber layer 102 on the innermost tire surface of the inner liner 15 by suppressing exposure of the side end portions 102a, 102a of the second rubber layer 102 in the rubber ribbon 100.

[0029] As far as the inventors know, no effort has been made to prevent the second rubber layer 102 from being exposed to the tire innermost surface of the inner liner 15 at the end (the leading end 100b or the rear end 100c) of the rubber ribbon 100 in the ribbon longitudinal direction D3. Therefore, in this embodiment, the first rubber layer 101 in the rubber ribbon 100 is made to protrude in the ribbon longitudinal direction D3 beyond the end (the leading end 102b and / or the rear end 102c) of the second rubber layer 102, thereby suppressing exposure of the second rubber layer 102 at the tire innermost surface of the inner liner 15.

[0030] The cross-sectional shape of the rubber ribbon 100 in Figures 3A and 4 can be identified in the cross section of the tire after vulcanization molding. By cutting the tire 1 with a sharp blade or the like, the cross-sectional shapes of the first rubber layer 101 and the second rubber layer 102 can be determined from the shape of the rubber interface observed thinly on the cut surface.

[0031] [Extrusion molding equipment and molding drum] Next, an example of the extrusion molding device 20 for molding the rubber ribbon 100 and the molding drum 400 for molding the inner liner rubber 500 will be described with reference to FIGS.

[0032] As shown in FIG. 8, the extrusion molding device 20 includes a first rubber extruder 21 that extrudes a first rubber, a first rubber supply section 22 that supplies the first rubber, a second rubber extruder 23 that extrudes a second rubber, a second rubber supply section 24 that supplies the second rubber, and a die 25 that molds the supplied first rubber and second rubber into a rubber ribbon 100 and discharges it in a ribbon discharge direction D6.

[0033] The rubber ribbon 100 discharged from the die 25 is transported by a plurality of transport rollers 200 and pressed against a forming drum 400 by a pressure roller 300. The forming drum 400 is configured to be movable in its axial direction (a direction perpendicular to the paper surface of FIG. 8) and rotatable around its axis 400a. The forming drum 400, which has received the rubber ribbon 100, is moved in the axial direction while rotating, whereby the rubber ribbon 100 is wound spirally around the forming drum 400. The rubber ribbon 100 is cut to an arbitrary length by cutting means (not shown).

[0034] The first rubber supplying section 22 is attached to the first rubber extruder 21. As shown in Fig. 10, the first rubber supplying section 22 includes a first rubber supplying path 221 that supplies the first rubber extruded from the first rubber extruder 21 to the die 25. The first rubber supplying path 221 is disposed on the first ribbon thickness direction D41 side of the die 25.

[0035] As shown in Fig. 8, the second rubber supplying section 24 is attached to the second rubber extruder 23. As shown in Fig. 10, the second rubber supplying section 24 includes a second rubber supplying path 241 that supplies the second rubber extruded from the second rubber extruder 23 to the die 25. The second rubber supplying path 241 is disposed upstream of the die 25 in the ribbon discharge direction D6.

[0036] 8 to 10, the die 25 is disposed at the tip of the extrusion molding device 20, and is attached to the first rubber supply unit 22 and the second rubber supply unit 24. The die 25 includes a first rubber inflow path 251 into which the first rubber flows, a second rubber inflow path 252 into which the second rubber flows, and a rubber ribbon discharge path 253 that molds the first rubber and the second rubber into a rubber ribbon 100 and discharges it in a ribbon discharge direction D6.

[0037] The first rubber inlet path 251 extends from the first rubber supply path 221 to the rubber ribbon discharge path 253. The first rubber inlet path 251 extends in a direction intersecting with the second rubber inlet path 252, and merges with the second rubber inlet path 252 at a merging position P1. The first rubber inlet path 251 is formed in a flat plate shape.

[0038] The first rubber inlet passage 251 intersects with one side (first ribbon thickness direction D41) of the second rubber inlet passage 252 in the ribbon thickness direction D4, including the side end 252a of the second rubber inlet passage 252 in the ribbon width direction D5. With this configuration, the side end in the ribbon width direction D5 of the second rubber flowing in from the second rubber inlet passage 252 can be covered by the first rubber flowing in from the first rubber inlet passage 251. This allows the side end 102a of the second rubber layer 102 in FIG. 3A to be appropriately covered by the first rubber layer 101.

[0039] The second rubber inlet path 252 extends from the second rubber supply path 241 to the rubber ribbon discharge path 253. The second rubber inlet path 252 is formed in a substantially triangular shape when viewed in the ribbon discharge direction D6. The second rubber inlet path 252 extends in the same direction (ribbon discharge direction D6) as the rubber ribbon discharge path 253. The rubber ribbon discharge path 253 extends from the joining position P1 toward the outside of the die 25. The rubber ribbon discharge path 253 is formed in a substantially triangular shape when viewed in the ribbon discharge direction D6.

[0040] [Manufacturing method of pneumatic tires] Next, an example of a method for manufacturing the pneumatic tire 1 will be described with reference to FIGS.

[0041] First, the process of forming the rubber ribbon 100 will be described. The process of forming the rubber ribbon 100 includes at least one of a leading end forming stage in which the first rubber R1 is supplied to the rubber ribbon discharge path 253 of the extrusion molding device 20 before the second rubber R2, thereby causing the first rubber layer 101 to protrude in the ribbon longitudinal direction D3 from the leading end 102b of the second rubber layer 102 in the ribbon longitudinal direction D3, and a rear end forming stage in which the first rubber R1 is supplied to the rubber ribbon discharge path 253 after the supply of the second rubber R2 to the rubber ribbon discharge path 253 is stopped, thereby causing the first rubber layer 101 to protrude in the ribbon longitudinal direction D3 from the rear end 102c of the second rubber layer 102. In this embodiment, the process of forming the rubber ribbon 100 includes both the leading end forming stage and the rear end forming stage.

[0042] The process of forming the rubber ribbon 100 in this embodiment will be specifically described. As shown in Fig. 11(a), the second rubber R2 is supplied from the second rubber supply path 241 of the extrusion molding device 20, and the second rubber R2 is filled into the second rubber inflow path 252. Then, after the supply of the second rubber R2 is stopped, the first rubber R1 is supplied from the first rubber supply path 221 of the extrusion molding device 20, and the first rubber R1 is supplied to the rubber ribbon discharge path 253. The supply amount of the first rubber R1 to the rubber ribbon discharge path 253 is appropriately set according to the length L1 of the first rubber layer 101 (see Fig. 4).

[0043] 11(b), after the first rubber R1 is filled into the rubber ribbon discharge passage 253, the supply of the second rubber R2 is resumed, and the first rubber R1 and the second rubber R2 are simultaneously supplied. This tip forming stage allows the first rubber layer 101 in the rubber ribbon 100 to protrude beyond the tip 102b of the second rubber layer 102.

[0044] 11(c), the first rubber R1 and the second rubber R2 are supplied simultaneously to continuously mold and discharge the rubber ribbon 100. Since the first rubber inflow path 251 intersects with the side end 252a of the second rubber inflow path 252, the side end of the second rubber R2 in the ribbon width direction D5 can be covered with the first rubber R1, and the side end 102a of the second rubber layer 102 in the rubber ribbon 100 can be appropriately covered with the first rubber layer 101.

[0045] 11(d), the supply of the second rubber R2 is stopped immediately before the rubber ribbon 100 reaches an arbitrary length, and only the first rubber R1 is supplied to the rubber ribbon discharge path 253. The amount of the first rubber R1 supplied to the rubber ribbon discharge path 253 is appropriately set according to the length L2 (see FIG. 4) of the first rubber layer 101. This rear end forming stage allows the first rubber layer 101 in the rubber ribbon 100 to protrude beyond the rear end 102c of the second rubber layer 102. The rear end 100c of the rubber ribbon 100 is formed by cutting by a cutting means after it is discharged from the die 25.

[0046] Next, a process for forming the inner liner rubber 500 will be described. As shown in Fig. 8, the rubber ribbon 100 discharged from the die 25 is transported by a plurality of transport rollers 200, and pressed against the forming drum 400 by a pressure roller 300. Then, the forming drum 400 is moved in the axial direction of the forming drum 400 while rotating, and the rubber ribbon 100 is wound spirally around the forming drum 400. In this way, the inner liner rubber 500 can be formed with the rubber ribbon 100.

[0047] Next, an unvulcanized tire is molded using the inner liner rubber 500. Finally, the unvulcanized tire is vulcanized in a vulcanization mold to manufacture the tire 1. The manufacturing method of the pneumatic tire 1 of the present disclosure can be performed in the same manner as the conventional tire manufacturing process except for the process related to the inner liner rubber 500, and therefore other explanations will be omitted.

[0048] As described above, in this embodiment, the pneumatic tire 1 has an inner liner 15 formed by a spirally wound rubber ribbon 100, and the rubber ribbon 100 has a first rubber layer 101 that forms the innermost tire surface of the rubber ribbon 100, and a second rubber layer 102 that is arranged outside the first rubber layer 101 in the tire radial direction D2, and it is preferable that the first rubber layer 101 protrudes in the ribbon longitudinal direction D3 beyond at least one of the leading end 102b and the trailing end 102c of the second rubber layer 102 in the ribbon longitudinal direction D3.

[0049] According to this configuration, it is possible to prevent the ends (the leading end 102b and / or the trailing end 102c) of the second rubber layer 102 in the ribbon longitudinal direction D3 of the inner liner 15 from being exposed to the innermost surface of the tire. This makes it possible to prevent the second rubber layer 102 from being exposed to the innermost surface of the tire of the inner liner 15, and it is possible to provide a pneumatic tire 1 including an inner liner 15 with excellent air barrier properties.

[0050] Furthermore, as in the pneumatic tire 1 according to the above embodiment, it is preferable that the first rubber layer 101 protrudes in the ribbon longitudinal direction D3 beyond each of the leading end 102b and the trailing end 102c of the second rubber layer 102 in the ribbon longitudinal direction D3.

[0051] With this configuration, it is possible to prevent the ends (the leading end 102b and the trailing end 102c) of the second rubber layer 102 in the ribbon longitudinal direction D3 of the inner liner 15 from being exposed to the innermost surface of the tire. This makes it possible to further prevent the second rubber layer 102 of the inner liner 15 from being exposed to the innermost surface of the tire.

[0052] Also, like the pneumatic tire 1 according to the above embodiment, a configuration in which the side end portion 102a of the second rubber layer 102 in the ribbon width direction D5 is covered with the first rubber layer 101 is preferable.

[0053] This configuration can prevent the side end portion 102a of the second rubber layer 102 in the inner liner 15 from being exposed to the innermost surface of the tire. This can further prevent the second rubber layer 102 from being exposed to the innermost surface of the tire of the inner liner 15.

[0054] Furthermore, as in the above embodiment, the manufacturing method of the pneumatic tire 1 includes a step of molding a rubber ribbon 100 having a first rubber layer 101 forming the innermost surface of the tire and a second rubber layer 102 arranged outside the first rubber layer 101 in the tire radial direction D2, and a step of spirally winding the rubber ribbon 100 to form the inner liner rubber 500. Preferably, the step of molding the rubber ribbon 100 is performed by causing the first rubber layer 101 to protrude in the ribbon longitudinal direction D3 beyond at least one of the leading end 202b and the trailing end 102c of the second rubber layer 102 in the ribbon longitudinal direction D3.

[0055] According to this method, it is possible to prevent the end portions (the leading end portion 102b and / or the trailing end portion 102c) of the second rubber layer 102 in the ribbon longitudinal direction D3 of the inner liner rubber 500 from being exposed to the inside (for example, the molding drum 400 side). This makes it possible to prevent the second rubber layer 102 from being exposed on the innermost surface of the tire of the inner liner 15, and it is possible to provide a manufacturing method for a pneumatic tire 1 including an inner liner 15 with excellent air barrier properties.

[0056] Furthermore, as in the above embodiment, the process of forming the rubber ribbon 100 in the manufacturing method of the pneumatic tire 1 is preferably a method in which the first rubber layer 101 protrudes in the ribbon longitudinal direction D3 beyond each of the leading end 102b and the trailing end 102c of the second rubber layer 102 in the ribbon longitudinal direction D3.

[0057] According to this method, the ends (the leading end 102b and the trailing end 102c) of the second rubber layer 102 in the ribbon longitudinal direction D3 of the inner liner rubber 500 can be prevented from being exposed to the inside (e.g., the side of the molding drum 400), and exposure of the second rubber layer 102 on the innermost surface of the tire of the inner liner 15 can be further prevented.

[0058] Furthermore, as in the above embodiment, the process of molding the rubber ribbon 100 in the manufacturing method of the pneumatic tire 1 preferably includes at least one of a leading end molding stage in which the first rubber R1 is supplied to the rubber ribbon discharge path 253 of the extrusion molding device 20 before the second rubber R2, thereby causing the first rubber layer 101 to protrude in the ribbon longitudinal direction D3 beyond the leading end 102b in the ribbon longitudinal direction D3 of the second rubber layer 102, and a rear end molding stage in which the supply of the second rubber R2 to the rubber ribbon discharge path 253 is stopped and then the first rubber R1 is supplied to the rubber ribbon discharge path 253, thereby causing the first rubber layer 101 to protrude in the ribbon longitudinal direction D3 beyond the rear end 102c in the ribbon longitudinal direction D3 of the second rubber layer 102.

[0059] According to this method, the first rubber layer 101 in the rubber ribbon 100 can be reliably protruded in the ribbon longitudinal direction D3 beyond the ends (the leading end 102b and / or the trailing end 102c) of the second rubber layer 102 in the ribbon longitudinal direction D3.

[0060] As in the above embodiment, the step of forming the rubber ribbon 100 in the manufacturing method of the pneumatic tire 1 is preferably a method in which the side end portion 102a of the second rubber layer 102 in the ribbon width direction D5 is covered with the first rubber layer 101.

[0061] According to this method, it is possible to prevent the side end portion 102a of the second rubber layer 102 in the inner liner rubber 500 from being exposed to the inside (for example, the molding drum 400 side). This makes it possible to further prevent the exposure of the second rubber layer 102 on the innermost tire surface of the inner liner 15.

[0062] The pneumatic tire 1 and the manufacturing method thereof are not limited to the configurations of the above-mentioned embodiments, and are not limited to the above-mentioned effects. In addition, the pneumatic tire 1 and the manufacturing method thereof can be modified in various ways without departing from the spirit of the present invention. [Explanation of symbols]

[0063] 1: pneumatic tire, 11: bead, 12: sidewall, 13: tread, 14: carcass ply, 15: inner liner, 20: extrusion molding device, 21: first rubber extruder, 22: first rubber supply section, 221: first rubber supply passage, 23: second rubber extruder, 24: second rubber supply section, 241: second rubber supply passage, 25: nozzle, 251: first rubber inlet passage, 252: second rubber inlet passage, 252a: side end portion, 253: Rubber ribbon discharge path, 100: rubber ribbon, 100a: side end, 100b: tip, 100c: rear end, 101: first rubber layer, 102: second rubber layer, 102a: side end, 102b: tip, 102c: rear end, 200: conveying roller, 300: pressure roller, 400: molding drum, 500: inner liner rubber, 500a: side end, P1: joining position, R1: first rubber, R2: second rubber, S1: tire equatorial plane

Claims

1. an inner liner formed by a spirally wrapped rubber ribbon; The rubber ribbon includes a first rubber layer that forms an innermost tire surface of the rubber ribbon, and a second rubber layer that is disposed on an outer side in a tire radial direction of the first rubber layer, the first rubber layer protrudes in the ribbon longitudinal direction beyond at least one of a leading end and a trailing end of the second rubber layer in the ribbon longitudinal direction.

2. The pneumatic tire according to claim 1 , wherein the first rubber layer protrudes in the ribbon longitudinal direction beyond each of a leading end and a trailing end in the ribbon longitudinal direction of the second rubber layer.

3. The pneumatic tire according to claim 1 or 2, wherein a side end portion in a ribbon width direction of the second rubber layer is covered with the first rubber layer.

4. A step of forming a rubber ribbon including a first rubber layer forming an innermost surface of a tire and a second rubber layer disposed on an outer side in a tire radial direction of the first rubber layer; and a step of winding the rubber ribbon in a spiral shape to form an inner liner rubber. In the step of forming the rubber ribbon, the first rubber layer is caused to protrude in the ribbon longitudinal direction beyond at least one of a leading end and a trailing end of the second rubber layer in the ribbon longitudinal direction.

5. The method for manufacturing a pneumatic tire according to claim 4 , wherein the step of forming the rubber ribbon causes the first rubber layer to protrude in the ribbon longitudinal direction beyond each of a leading end and a trailing end in the ribbon longitudinal direction of the second rubber layer.

6. The step of forming the rubber ribbon includes: a tip portion forming step of supplying a first rubber before a second rubber to a rubber ribbon discharge path of an extrusion molding device, so that the first rubber layer protrudes in the ribbon longitudinal direction beyond a tip portion of the second rubber layer in the ribbon longitudinal direction; And, a rear end forming step of supplying the first rubber to the rubber ribbon discharge path after stopping the supply of the second rubber to the rubber ribbon discharge path, thereby causing the first rubber layer to protrude in the ribbon longitudinal direction beyond the rear end of the second rubber layer in the ribbon longitudinal direction; The method for producing a pneumatic tire according to claim 4 or 5, comprising at least one of the steps of:

7. The method for manufacturing a pneumatic tire according to any one of claims 4 to 6, wherein in the step of forming the rubber ribbon, side ends in a ribbon width direction of the second rubber layer are covered with the first rubber layer.

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