Pneumatic tires, methods for manufacturing pneumatic tires

Abstract

This invention provides a pneumatic tire equipped with a sealant layer and a sound-absorbing layer, which is highly effective in suppressing the deterioration of puncture resistance. [Solution] The tire 1 comprises a sealant layer 60 disposed on the inner surface of the inner liner 50 on the inner side of the tire cavity, and a sound-absorbing layer 70 disposed on the inner side of the sealant layer 60 on the inner side of the tire cavity. The sealant layer 60 has an inner opposing region 601a, which is a region where the sealant layer 60 and the sound-absorbing layer 70 face each other and is located inward in the tire axial direction from both ends of the sound-absorbing layer 70 in the tire axial direction in the tire axial cross-section, and an outer opposing region 601b, which is a region where the sealant layer 60 and the sound-absorbing layer 70 face each other and is located outward in the tire axial direction from the inner opposing region 601a and inward in the tire axial direction from both ends of the sound-absorbing layer 70 in the tire axial cross-section. The bonding force between the sealant layer 60 and the sound-absorbing layer 70 is higher in the outer opposing region 601b than in the inner opposing region 601a.

Description

Technical Field

[0001] The present disclosure relates to pneumatic tires and a method for manufacturing pneumatic tires.

Background Art

[0002] Conventionally, there is known a pneumatic tire provided with a puncture prevention function in which a hole in the tire formed when a foreign object such as a nail pierces the tire is automatically blocked by a sealant layer provided on the inner surface of the tire. For example, Patent Document 1 describes a pneumatic tire in which a sealant layer is provided on the inner surface of the tire and a sound deadening body is provided inside the sealant layer. Since the contact between the sealant layer and the sound deadening body causes a decrease in puncture resistance performance, in the pneumatic tire of Patent Document 1, the surface of the sealant layer is formed in a cross-sectional wave shape or the like to reduce the contact portion between the sealant layer and the sound deadening body and suppress the decrease in puncture resistance performance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration of Patent Document 1 described above, there are also many positions where the sealant layer contacts the sound deadening body near the center of the tread, and at those positions, the decrease in puncture resistance performance could not be suppressed.

[0005] An object of the present disclosure is to provide a pneumatic tire provided with a sealant layer and a sound absorption layer, which has a high effect of suppressing a decrease in puncture resistance performance.

Means for Solving the Problems

[0006] The pneumatic tire of this disclosure comprises a pair of beads, a pair of sidewalls extending radially outward from each of the pair of beads, a tread disposed between the pair of sidewalls and having a contact surface, a carcass ply spanning between the pair of beads, an inner liner disposed on the inner side of the carcass ply on the inner side of the inner liner on the inner side of the inner liner, and a sound-absorbing layer disposed on the inner side of the sealant layer on the inner side of the sealant layer, wherein the sealant layer has an inner opposing region where the sealant layer and the sound-absorbing layer face each other, which is an area in the inner tire axial direction of the tire axial cross-section that is more inward in the tire axial direction than both ends of the sound-absorbing layer in the tire axial direction, and an outer opposing region where the sealant layer and the sound-absorbing layer face each other, which is an area in the outer tire axial direction of the tire axial cross-section that is more outward in the tire axial direction than the inner opposing region and more inward in the tire axial direction than both ends of the sound-absorbing layer, and the bonding force between the sealant layer and the sound-absorbing layer is higher in the outer opposing region than in the inner opposing region. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide a pneumatic tire that includes a sealant layer and a sound-absorbing layer, and is highly effective in suppressing the deterioration of puncture resistance. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a cross-sectional view in the axial direction of tire 1, which is a pneumatic tire according to this embodiment. [Figure 2] This is a diagram illustrating the manufacturing method of tire 1. [Figure 3] This is a diagram illustrating the manufacturing method of tire 1. [Figure 4] This is a diagram illustrating the manufacturing method of tire 1. [Figure 5] This is a schematic diagram showing an enlarged view of the portion where the outer opposing region 601b and the sound-absorbing layer 70 are facing each other. [Figure 6] This is a schematic diagram showing an enlarged view of the portion where the inner opposing region 601a and the sound-absorbing layer 70 are facing each other. [Modes for carrying out the invention]

[0009] The embodiments will be described below with reference to the drawings. Figure 1 is a diagram showing a cross-sectional view in the axial direction of tire 1, which is a pneumatic tire according to this embodiment. Tire 1 is, for example, a tire for a passenger car. The basic structure of tire 1 is symmetrical in the cross-section in the axial direction of tire 1. In the figure, the symbol S1 is the tire equatorial plane. The tire equatorial plane S1 is a plane that is perpendicular to the tire rotation axis (tire meridian) and is located at the center in the axial direction of tire 1.

[0010] The cross-sectional view in Figure 1 is an axial cross-sectional view (tire meridian cross-section) of the tire in an unloaded state, with tire 1 mounted on a specified rim and filled to the specified internal pressure. The specified rim refers to the standard rim defined by JATMA corresponding to the tire size. The specified internal pressure is, for example, 180 kPa if the tire is for a passenger car.

[0011] Here, the tire axis direction is the direction parallel to the tire rotation axis, and in the cross-sectional view of Figure 1, it is the left-right direction on the paper. In Figure 1, it is shown as the tire axis direction X. The inner direction in the tire axis direction is the direction approaching the tire equatorial plane S1, and in Figure 1, it is the center side of the paper. The outer direction in the tire axis direction is the direction away from the tire equatorial plane S1, and in Figure 1, it is the left and right sides of the paper. The tire radial direction is the direction perpendicular to the tire rotation axis, and in Figure 1, it is the up-down direction on the paper. In Figure 1, it is shown as the tire radial direction Y. The outer direction in the tire radial direction is the direction away from the tire rotation axis, and in Figure 1, it is the bottom side of the paper. The inner direction in the tire radial direction is the direction approaching the tire rotation axis, and in Figure 1, it is the top side of the paper.

[0012] As shown in Figure 1, the tire 1 comprises a pair of beads 10 provided on both sides of the tire axial direction, a pair of sidewalls 20 extending radially outward from each of the pair of beads 10, a tread 30 positioned between the pair of sidewalls 20, a carcass ply 40 positioned between the pair of beads 10, and an inner liner 50 positioned on the inner side of the carcass ply 40.

[0013] The bead 10 comprises a bead core 11, a bead filler 12 extending radially outward from the bead core 11, a chaff 13, and a rim strip rubber 14.

[0014] The bead core 11 is an annular member formed by winding a rubber-coated metal bead wire multiple times, and is a member that fixes the air-filled tire 1 to the rim. The bead filler 12 is a rubber member that tapers towards the outside in the radial direction of the tire. The bead filler 12 is a member provided to increase the rigidity of the peripheral part of the bead 10 and ensure high maneuverability and stability. The bead filler 12 is made of rubber that is harder than the surrounding rubber member, for example.

[0015] The chaff 13 is located on the radially inner side of the carcass ply 40, which is provided around the bead core 11. The rim strip rubber 14 is positioned on the axially outer side of the chaff 13 and carcass ply 40. The rim strip rubber 14 is a component that contacts the rim on which the tire 1 is mounted.

[0016] The sidewall 20 includes sidewall rubber 21 positioned on the axial side of the carcass ply 40. The sidewall rubber 21 constitutes the outer wall surface of the tire 1. The sidewall rubber 21 is the part that flexes the most when the tire 1 performs its cushioning action, and is usually made of a flexible rubber with fatigue resistance.

[0017] The tread 30 comprises an endless belt 31 and a cap ply 32, and tread rubber 33.

[0018] The belt 31 is disposed on the outer side in the tire radial direction of the carcass ply 40. The cap ply 32 is disposed on the outer side in the tire radial direction of the belt 31. The belt 31 is a member for reinforcing the tread 30. The belt 31 of the present embodiment has a two-layer structure including an inner belt and an outer belt 312. Both the inner belt 311 and the outer belt 312 have a structure in which a plurality of cords such as steel cords are covered with rubber. Note that the belt 31 is not limited to a two-layer structure, and may have a single-layer structure or a structure having three or more layers.

[0019] The cap ply 32 is a member for reinforcing the tread 30 together with the belt 31. The cap ply 32 has a structure in which a plurality of insulating organic fiber cords such as polyamide fibers are covered with rubber. By providing the cap ply 32, it is possible to improve durability and reduce road noise during running.

[0020] The tread rubber 33 is disposed on the outer side in the tire radial direction of the cap ply 32. The tread rubber 33 is a member that constitutes the ground contact surface (tread surface) 331 during normal running. The ground contact surface 331 of the tread rubber 33 is provided with a tread pattern 34 composed of, for example, a plurality of grooves. The tread pattern 34 has a plurality of main grooves 341 arranged in the tire axial direction. Each of the plurality of main grooves 341 extends along the tire circumferential direction.

[0021] The carcass ply 40 constitutes a ply that forms the framework of the tire 1. The carcass ply 40 is embedded in the tire 1 in a manner that passes between a pair of beads 10 through a pair of sidewalls 20 and the tread 30. The carcass ply 40 includes a plurality of carcass cords that form the framework of the tire 1. The plurality of carcass cords extend, for example, in the tire axial direction and are arranged side by side in the tire circumferential direction. The carcass cords are composed of insulating organic fiber cords such as polyester and polyamide. The plurality of carcass cords are covered with rubber to form the carcass ply 40.

[0022] The carcass ply 40 has a ply body portion 401 that extends from one bead core 11 to the other bead core 11 and extends between the tread 30 and the bead 10, a pair of bent portions 402 that are folded back by the bead core 11 from the ply body portion 401, and a pair of folded-back portions 403 that extend radially outward in the tire diameter direction from each of the bent portions 402. The ply body portion 401, the bent portions 402, and the folded-back portions 403 are continuous.

[0023] The ply body portion 401 is disposed axially inward of the bead core 11 and the bead filler 12 in the tire radial direction. The folded-back portion 403 is disposed axially outward of the bead core 11 and the bead filler 12 in the tire radial direction. In portions other than the bead core 11 and the bead filler 12, the folded-back portion 403 is overlapped with the ply body portion 401. The bent portion 402 constitutes the innermost portion in the tire radial direction of the carcass ply 40.

[0024] The carcass ply 40 of the present embodiment has a single-layer structure, but the carcass ply 40 is not limited to a single-layer structure and may have a two-layer structure or a structure having three or more layers.

[0025] The chafer 13 of the bead 10 described above is provided so as to surround the radially inner end portion of the carcass ply 40 including the bent portion 402. Further, the rim strip rubber 14 is disposed axially outward of the chafer 13 and the folded-back portion 403 of the carcass ply 40. The radially outer end portion of the rim strip rubber 14 is covered with the sidewall rubber 21 described above.

[0026] The inner liner 50 covers the inner surface of the tire between the pair of beads. The inner liner 50 covers the inner surface of the ply body portion 401 of the carcass ply 40 and the inner surface of the chafer 13 of the pair of beads 10. The inner liner 50 is made of air permeation-resistant rubber and prevents air in the tire inner cavity from leaking to the outside.

[0027] As shown in Figure 1, the tire 1 according to this embodiment further comprises a sealant layer 60 and a sound-absorbing layer 70.

[0028] The sealant layer 60 is positioned on the inner surface 501 of the inner liner 50 that is at least on the inner side of the tire cavity corresponding to the tread 30. The sealant layer 60 is attached to the inner liner 50 by its own adhesive properties. The thickness of the sealant layer 60 is, for example, about 1 mm to 10 mm. By providing the sealant layer 60, if a hole is created in the tread 30 that reaches the sealant layer 60, for example, when a nail is driven into it, the hole is automatically sealed by the sealant layer 60, preventing a puncture.

[0029] A sealant material (sealant) that is a fluid with adhesive properties can be used to form the sealant layer 60. Conventional sealant materials known for puncture sealing can be used as the sealant material for the sealant layer 60. Examples of sealant materials that can be used for the sealant layer 60 include silicone compounds, styrene compounds, urethane compounds, and ethylene compounds. More specifically, an adhesive sealant material can be used, which is made by blending unvulcanized or semi-vulcanized butyl rubber with a plasticizer such as polyisobutylene or polybutene, a tackifier such as a thermoplastic olefin / diolefin copolymer, and a filler such as carbon black or silica. However, the sealant material is not limited to these, and other conventionally used and known sealant materials (sealants) may also be used to form the sealant layer 60.

[0030] The sound-absorbing layer 70 is positioned on the inner surface 601 of the sealant layer 60 on the inner side of the tire cavity. The sound-absorbing layer 70 is attached to the sealant layer 60 by the adhesive properties of the sealant layer 60. The material (sound-absorbing material) constituting the sound-absorbing layer 70 in this embodiment is a sponge with numerous pores formed from a foamed material, and a foamed resin such as polyurethane foam is preferably used. The sound-absorbing layer 70 in this embodiment has a substantially rectangular cross-sectional shape in the tire axial cross-section shown in Figure 1, and is positioned symmetrically with respect to the tire equatorial plane S1 as the central plane of symmetry.

[0031] The sound-absorbing layer 70 is constructed by attaching at least one sheet-like sound-absorbing material in a substantially ring shape along the inner surface 601 of the sealant layer 60. The sound-absorbing layer 70 can be constructed by joining the ends of a single sound-absorbing material along the inner surface 601 of the sealant layer 60 in the circumferential direction of the tire in a substantially ring shape. The sound-absorbing layer 70 may also be constructed in an annular shape with two or more members divided in the circumferential direction of the tire, or it may be arranged intermittently in the circumferential direction of the tire at predetermined intervals rather than in an annular shape. Alternatively, a single sound-absorbing material that has been pre-formed into an annular shape may be joined to the inner surface 601 of the sealant layer 60. By providing the sound-absorbing layer 70, it is possible to reduce in-vehicle noise by reducing cavity resonance that occurs in the tire cavity and absorbing road noise during driving.

[0032] The entire outer surface of the sound-absorbing layer 70 in the tire radial direction (the outer peripheral surface of the sound-absorbing layer 70) is in contact with the inner surface 601 of the sealant layer 60. However, in this embodiment, the bonding force between the sealant layer 60 and the sound-absorbing layer 70 varies greatly depending on the region in which the sealant layer 60 and the sound-absorbing layer 70 are in contact.

[0033] In order for the sealant layer 60 to prevent punctures, it is necessary for the sealant layer 60 to be deformable. However, in areas where the sealant layer 60 and the sound-absorbing layer 70 are firmly bonded, the sound-absorbing layer 70 may inhibit or suppress the deformation of the sealant layer 60, raising concerns about a decrease in the puncture resistance performance that the sealant layer 60 is supposed to provide.

[0034] Conventionally, there was a technique, such as the invention described in Japanese Patent Publication No. 2021-46130 (Patent Document 1), in which the surface of the sealant layer was formed with a wavy cross-section or the like to reduce the contact area between the sealant layer and the sound-dampening material, thereby suppressing the deterioration of puncture resistance. However, in the above-mentioned conventional technique, there were many positions where the sealant layer contacted the sound-dampening material even near the center of the tread, and the deterioration of puncture resistance could not be suppressed at those positions. Furthermore, in the above-mentioned conventional technique, the thickness of the sealant layer was made to be inconsistent, for example, by forming the surface of the sealant layer with a wavy cross-section or the like, but when using a fluid sealant material, it was difficult to form the sealant layer with an inconsistent thickness.

[0035] Therefore, in the tire 1 of this embodiment, the deterioration of puncture resistance is suppressed by changing the contact state between the sealant layer 60 and the sound-absorbing layer 70 depending on the location in the area where they are in contact. This point will be explained in detail below.

[0036] The inner surface 601 of the sealant layer 60 in this embodiment has an inner opposing region 601a, an outer opposing region 601b, 601b, and a non-opposing region 601c, 601c. In Figure 1, etc., different types of hatching are used to indicate the inner opposing region 601a, the outer opposing regions 601b, 601b, and the non-opposing regions 601c, 601c; this is for the purpose of facilitating understanding. In this embodiment, as will be described later, the entire sealant layer 60 is constructed using the same sealant material. Therefore, the difference between the inner opposing region 601a and the outer opposing regions 601b, 601b may not be clearly distinguishable in cross-section.

[0037] The inner opposing region 601a is the region where the sealant layer 60 and the sound-absorbing layer 70 face each other, and is located inward in the tire axial direction from both ends (ends 71, 71) of the sound-absorbing layer 70 in the tire axial direction in the tire axial cross-section. The inner opposing region 601a is positioned from the position through which the tire equatorial plane S1 passes, that is, the center in the tire axial direction, outward in the tire axial direction, to a position where it connects with the outer opposing regions 601b, 601b described later.

[0038] The outer opposing regions 601b, 601b are regions where the sealant layer 60 and the sound-absorbing layer 70 face each other, and in the tire axial cross-section, they are regions that are further outward in the tire axial direction than the inner opposing region 601a, and further inward in the tire axial direction than both ends (ends 71, 71) of the sound-absorbing layer 70. The width in the tire axial direction of one outer opposing region 601b is approximately equal to the width in the tire axial direction of the other outer opposing region 601b.

[0039] The non-opposing regions 601c, 601c are located further outward in the tire axial direction than the outer opposing regions 601b, 601b, and are regions that do not face the sound-absorbing layer 70. The width in the tire axial direction of one non-opposing region 601c is approximately equal to the width in the tire axial direction of the other non-opposing region 601c.

[0040] Both the inner opposing region 601a and the outer opposing regions 601b, 601b are positioned opposite the sound-absorbing layer 70, but the bonding force between the sealant layer 60 and the sound-absorbing layer 70 is higher in the outer opposing regions 601b, 601b than in the inner opposing region 601a. ​​In this embodiment, in the outer opposing regions 601b, 601b, where the sealant layer 60 and the sound-absorbing layer 70 are in contact, the sealant layer 60 and the sound-absorbing layer 70 are bonded together. On the other hand, in the inner opposing region 601a, the sealant layer 60 and the sound-absorbing layer 70 are merely in contact and not substantially bonded together. Note that the state of not substantially bonded together includes not only the case where the bonding force between the two is zero, but also the case where they are in contact with a slight bonding force due to intermolecular forces, etc.

[0041] In other words, in the inner opposing region 601a, the bonding force between the sealant layer 60 and the sound-absorbing layer 70 is zero or very small. Therefore, the sound-absorbing layer 70 does not suppress the deformation of the sealant layer 60, or the sound-absorbing layer 70 has almost no effect in suppressing the deformation of the sealant layer 60. Consequently, the decrease in puncture resistance can be suppressed in the inner opposing region 601a.

[0042] Furthermore, by providing the outer opposing regions 601b, 601b, the sound-absorbing layer 70 is properly fixed within the tire cavity, and a stable noise suppression effect during driving can be obtained. In the outer opposing regions 601b, 601b, there is a risk of a decrease in puncture resistance, so it is desirable that the width of the outer opposing regions 601b, 601b in the tire axial direction be narrow in order to suppress the decrease in puncture resistance. On the other hand, from the viewpoint of fixing the sound-absorbing layer 70, it is desirable that the width of the outer opposing regions 601b, 601b in the tire axial direction be wide. Therefore, it is important to set the width of the outer opposing regions 601b, 601b in the tire axial direction to an appropriate value.

[0043] The width in the tire axial direction of the outer opposing regions 601b, 601b that face each other at both ends (ends 71, 71) of the sound-absorbing layer 70 is preferably between 10% and 30% of the tire axial direction width of the sound-absorbing layer 70. If the tire axial direction width of the outer opposing regions 601b, 601b is less than 10% of the tire axial direction width of the sound-absorbing layer 70, the fixing of the sound-absorbing layer 70 may become unstable. Also, if the tire axial direction width of the outer opposing regions 601b, 601b exceeds 30% of the tire axial direction width of the sound-absorbing layer 70, the proportion occupied by the outer opposing regions 601b, 601b becomes too large, which may reduce the puncture resistance performance of the sealant layer 60.

[0044] In this embodiment, the width of the outer opposing regions 601b, 601b in the tire axial direction is 15% of the width of the sound-absorbing layer 70 in the tire axial direction.

[0045] Furthermore, it is desirable that the width in the tire axial direction of the opposing outer opposing regions 601b, 601b at both ends (ends 71, 71) of the sound-absorbing layer 70 be between 10 mm and 20 mm. If the width in the tire axial direction of the outer opposing regions 601b, 601b is less than 10 mm, the fixing of the sound-absorbing layer 70 may become unstable. Also, if the width in the tire axial direction of the outer opposing regions 601b, 601b exceeds 20 mm, the proportion occupied by the outer opposing regions 601b, 601b becomes too large, which may reduce the puncture resistance performance of the sealant layer 60.

[0046] In this embodiment, the width of the outer opposing regions 601b, 601b in the tire axial direction is 12.5 mm each.

[0047] Furthermore, it is desirable that the width of the inner opposing region 601a is greater than the width of the outer opposing region 601b. That is, it is desirable that the relationship (width of inner opposing region 601a) > (width of outer opposing region 601b) is satisfied. By satisfying the above relationship, the possibility of exhibiting puncture resistance can be increased.

[0048] Furthermore, it is desirable that the width of the inner opposing region 601a is greater than the combined width of the two outer opposing regions 601b, 601b. In other words, it is desirable that the relationship (width of inner opposing region 601a) > 2 × (width of outer opposing region 601b) is satisfied. By satisfying the above relationship, the possibility of achieving puncture resistance can be increased.

[0049] Furthermore, the sealant layer 60 is positioned to be further outward in the tire axial direction than all of the main grooves 341. The main grooves 341 are areas where the thickness of the tread rubber 33 in the tire radial direction is thinner than other parts, making them highly susceptible to punctures by foreign objects. By positioning the sealant layer 60 to be further outward in the tire axial direction than all of the main grooves 341, the sealant layer 60 is positioned on the inner side of the tire cavity of all the main grooves 341, thereby increasing the likelihood of achieving puncture resistance.

[0050] Furthermore, it is desirable that the inner opposing region 601a is positioned further outward in the tire axial direction than all of the main grooves 341. This arrangement prevents the deformation of the sealant layer 60, which is located on the inner lumen side of all the main grooves 341, from being hindered by the sound-absorbing layer 70, thereby suppressing a decrease in puncture resistance.

[0051] Furthermore, the sealant layer 60 is positioned further outward from the belt 31 in the tire axial direction. This allows the sealant layer 60 to cover almost the entire area of ​​the tire cavity where there is a high risk of foreign objects puncturing it, thereby increasing the likelihood of achieving puncture resistance.

[0052] Furthermore, the sealant layer 60 is positioned further outward from the cap ply 32 in the tire axial direction. This allows the sealant layer 60 to cover almost the entire area of ​​the tire cavity where there is a high risk of foreign objects puncturing it, thereby increasing the likelihood of achieving puncture resistance.

[0053] Furthermore, the axial width of the non-opposing regions 601c and 601c is wider than the axial width of the outer opposing regions 601b and 601b, respectively. This increases the likelihood that the sealant layer 60 will not have its deformation suppressed by the sound-absorbing layer 70 over a wider area, thereby allowing it to exhibit puncture resistance.

[0054] (Manufacturing method) The inner opposing region 601a, the outer opposing regions 601b, 601b, and the non-opposing regions 601c, 601c of the sealant layer 60 described above can be formed from the same sealant material. Despite using the same sealant material, in this embodiment, a significant difference in bonding strength is created between the inner opposing region 601a and the outer opposing regions 601b, 601b. Figures 2 to 4 illustrate the manufacturing method of the tire 1. The following description will explain the method for forming such a characteristic sealant layer 60 (manufacturing method of the tire 1) with reference to Figures 2 to 4.

[0055] (Step of applying sealant to the area corresponding to the inner opposing region) The remaining parts of the tire 1 that do not have the sealant layer 60 and the sound-absorbing layer 70 are manufactured in advance by a conventionally known manufacturing method. Then, a sealant material that will form the base of the sealant layer 60 is applied to the inner surface 501 of the inner liner 50 using a nozzle (not shown) or the like (see Figure 2). For example, the sealant material may be discharged from the nozzle onto the inner surface 501 of the inner liner 50 while the tire 1 is rotated around its axis and the nozzle is moved in the axial direction of the tire. In this case, the sealant material is applied only to the region Ra (see Figure 2) corresponding to the inner opposing region 601a.

[0056] (Sealant curing step to form the inner opposing region) Next, the sealant applied to region Ra, which corresponds to the inner opposing region 601a, is cured to form the inner opposing region 601a (see Figure 2). Once the sealant hardens, it loses its fluidity, and even if it comes into contact with the sound-absorbing layer 70, the inner opposing region 601a and the sound-absorbing layer 70 will not adhere to each other. In this step of curing the sealant, heating or blowing air may be used to accelerate the hardening of the sealant as needed.

[0057] (Step of applying sealant material to the area axially outward of the inner opposing region 601a) Next, sealant material is applied to the area Rbc on the tire axial side of the inner opposing region 601a on the inner surface 501 of the inner liner 50 on the inner lumen side of the tire (see Figure 3). The application of sealant material in this step can also be carried out using a nozzle or the like (not shown), similar to the sealant material application step to the area Ra corresponding to the inner opposing region 601a described above.

[0058] (Step of joining the sound-absorbing layer 70) Next, before the sealant applied to the area Rbc on the tire axial side of the inner opposing region 601a hardens, the sound-absorbing layer 70 is positioned so that it overlaps the area Rb on the tire axial side of the sealant applied to the tire axial side of the inner opposing region 601a with the vicinity of the ends 71, 71 of the sound-absorbing layer 70 (see Figure 4). At this time, the area of ​​the sound-absorbing material 70 on the tire axial side overlaps with the area Ra corresponding to the inner opposing region 601a. ​​Also, the area Rc on the tire axial side of the sealant applied to area Rbc that is further out in the tire axial direction than where the sound-absorbing layer 70 is positioned is not covered by the sound-absorbing layer 70. After positioning the sound-absorbing layer 70, it may be pressed outward in the tire radial direction, i.e., toward the sealant layer 60, if necessary. The uncured sealant material and the vicinity of the edges 71, 71 of the sound-absorbing layer 70 are superimposed, and then, as the sealant material hardens, the outer opposing regions 601b, 601b and the non-opposing regions 601c, 601c are formed.

[0059] Figure 5 is a schematic diagram showing an enlarged view of the area where the outer opposing region 601b and the sound-absorbing layer 70 face each other. In Figure 5 and Figure 6, described later, only the sealant layer 60 and the sound-absorbing layer 70 are shown, schematically illustrating the voids S in the sound-absorbing layer 70, which is a porous material. When the uncured sealant material and the vicinity of the ends 71, 71 of the sound-absorbing layer 70 are superimposed, the sealant material partially penetrates into the voids S of the sound-absorbing layer 70. As the sealant material that has entered into the voids S hardens, in the outer opposing regions 601b, 601b, as shown in Figure 5, a portion of the sealant layer 60 penetrates into and engages with the voids S of the sound-absorbing layer 70. As a result, the outer opposing region 601b and the sound-absorbing layer 70 are strongly bonded, exhibiting high bonding strength.

[0060] Figure 6 is a schematic diagram showing an enlarged view of the area where the inner opposing region 601a and the sound-absorbing layer 70 are facing each other. In the inner opposing region 601a, the sealant material is already hardened when the sound-absorbing layer 70 is placed. Therefore, in the inner opposing region 601a, as shown in Figure 6, the sealant layer 60 does not penetrate into the void S of the sound-absorbing layer 70. Consequently, in the inner opposing region 601a, the bonding force between the sealant layer 60 and the sound-absorbing layer 70 is smaller than the bonding force between the sealant layer 60 and the sound-absorbing layer 70 in the outer opposing regions 601b, 601b.

[0061] This configuration can be more clearly understood by disassembling the tire 1 and peeling the sound-absorbing layer 70 from the sealant layer 60. Specifically, in the outer opposing regions 601b, 601b, the sealant layer 60 and the sound-absorbing layer 70 are bonded together, while in the inner opposing region 601a, the sealant layer 60 and the sound-absorbing layer 70 are facing each other in a state where they can be peeled off. Therefore, if the sound-absorbing layer 70 is forcibly peeled off from the sealant layer 60, in the outer opposing regions 601b, 601b, the sealant layer 60 or the sound-absorbing layer 70 will be partially damaged, and it will not peel off cleanly. In contrast, in the inner opposing region 601a, the sealant layer 60 and the sound-absorbing layer 70 can be easily peeled off cleanly.

[0062] The tire 1 according to the embodiment described above provides the following effects.

[0063] (1) The tire 1 according to this embodiment comprises a pair of beads 10, a pair of sidewalls 20 extending radially outward from each of the pair of beads 10, a tread 30 disposed between the pair of sidewalls 20 and having a contact surface, a carcass ply 40 spanning between the pair of beads 10, an inner liner 50 disposed on the inner cavity side of the carcass ply 40, a sealant layer 60 disposed on the inner surface of the inner cavity side of the inner liner 50, and a sound-absorbing layer 70 disposed on the inner cavity side of the sealant layer 60, wherein the sealant layer 60 is the sealant layer The sealant layer 60 and the sound-absorbing layer 70 face each other, and the sealant layer 60 has an inner facing region 601a which is inward in the tire axial direction from both ends of the sound-absorbing layer 70 in the tire axial direction in a cross-section of the tire, and an outer facing region 601b which is inward in the tire axial direction from the inner facing region 601a in a cross-section of the tire, and inward in the tire axial direction from both ends of the sound-absorbing layer 70, wherein the bonding force between the sealant layer 60 and the sound-absorbing layer 70 is higher in the outer facing region 601b than in the inner facing region 601a.

[0064] As a result, in the inner opposing region 601a, the sealant layer 60 is less likely to have its deformation inhibited by the sound-absorbing layer 70, thereby enhancing the effect of suppressing the decrease in puncture resistance.

[0065] (2) A pneumatic tire as described in (1), wherein in the outer opposing region 601b, the sealant layer 60 and the sound-absorbing layer 70 are bonded together, and in the inner opposing region 601a, the sealant layer 60 and the sound-absorbing layer 70 are facing each other in a manner that allows them to be peeled off.

[0066] This further enhances the effect of suppressing the deterioration of puncture resistance.

[0067] (3) A pneumatic tire as described in (1) or (2), wherein in the outer opposing region 601b, a portion of the sealant layer 60 penetrates and engages with the void S of the sound-absorbing layer 70, and in the inner opposing region 601a, the sealant layer 60 does not penetrate the void S of the sound-absorbing layer 70.

[0068] This enhances the adhesion between the sealant layer 60 and the sound-absorbing layer 70 in the outer opposing region 601b, more securely fixing the sound-absorbing layer 70 while improving the effect of suppressing the decrease in puncture resistance in the inner opposing region 601a.

[0069] (4) A pneumatic tire according to any one of (1) to (3), wherein the width in the tire axial direction of the outer opposing regions 601b that face each other at both ends of the sound-absorbing layer 70 is 10% or more and 30% or less of the width of the sound-absorbing layer 70 in the tire axial direction.

[0070] This makes it possible to enhance the effect of suppressing the decrease in puncture resistance while ensuring the stability of the sound-absorbing layer 70 in place.

[0071] (5) A pneumatic tire according to any of (1) to (4), wherein the width in the tire axial direction of the outer opposing regions 601b that face each other at both ends of the sound-absorbing layer 70 is 10 mm or more and 20 mm or less.

[0072] This makes it possible to enhance the effect of suppressing the decrease in puncture resistance while ensuring the stability of the sound-absorbing layer 70 in place.

[0073] (6) A pneumatic tire according to any one of (1) to (5), wherein the contact surface 331 of the tread 30 has at least one main groove 341 that extends continuously along the circumferential direction of the tire, and the sealant layer 60 is positioned to be outward in the tire axial direction from all of the main grooves 341.

[0074] This ensures that the sealant layer 60 is placed on the inner side of all main grooves 341, increasing the likelihood of achieving puncture resistance.

[0075] (7) A pneumatic tire according to any one of (1) to (3), wherein the tread 30 is provided with a belt 31 disposed on the outer circumference side of the carcass ply 40, and the sealant layer 60 is disposed to a position that is outward in the tire axial direction from the belt 31.

[0076] This allows the sealant layer 60 to cover almost the entire area of ​​the tire cavity where there is a high risk of foreign objects puncturing it, thereby increasing the likelihood of achieving puncture resistance.

[0077] (8) A pneumatic tire according to any one of (1) to (3), wherein the sealant layer 60 is located outward in the tire axial direction from the outer opposing region 601b and has non-opposing regions 601c that do not oppose the sound-absorbing layer 70, and the width of the non-opposing region 601c in the tire axial direction is wider than the width of the outer opposing region 601b in the tire axial direction, pneumatic tire (1).

[0078] This increases the likelihood that the sealant layer 60 will not have its deformation suppressed by the sound-absorbing layer 70 over a wider area, thereby allowing it to exhibit puncture resistance.

[0079] (9) A method for manufacturing a pneumatic tire according to any one of (1) to (3), comprising the steps of: applying a sealant material to a region corresponding to the inner opposing region 601a on the inner surface of the inner liner (50) on the inner cavity side of the tire; curing the sealant material applied to the region corresponding to the inner opposing region 601a to form the inner opposing region 601a; applying a sealant material to the region of the inner opposing region 601a on the outer side of the tire axial direction on the inner surface of the inner liner (50) on the inner cavity side of the tire; and placing the sound-absorbing layer 70 overlapping at least a portion with the sealant material applied to the region of the inner opposing region 601a on the outer side of the tire axial direction before the sealant material applied to the outer side of the tire axial direction of the inner opposing region 601a hardens.

[0080] This makes it possible to easily manufacture pneumatic tires in which the deformation of the sealant layer 60 in the inner opposing region 601a is not hindered by the sound-absorbing layer 70, thereby suppressing a decrease in puncture resistance.

[0081] (Transformed form) The embodiments described above are not limited to those described above, and various modifications and changes are possible, which are also within the scope of this disclosure.

[0082] (Modified form 1) In the embodiment described, the sealant layer 60 was shown to have a non-facing region 601c. However, the sealant layer may not have a region corresponding to the non-facing region and may face the sound-absorbing layer 70 over its entire surface.

[0083] (Modified form 2) In the embodiment described, the inner opposing region 601a and the outer opposing region 601b and non-opposing region 601c were treated with the same sealant material, and the inner opposing region 601a was cured first. However, the invention is not limited to this, and for example, the sealant material used for the inner opposing region 601a and the outer opposing region 601b and non-opposing region 601c may be different.

[0084] While each embodiment and its variations can be used in combination as appropriate, a detailed explanation is omitted. Furthermore, this disclosure is not limited to the embodiments described above. [Explanation of Symbols]

[0085] 1 tire 10 beads 11 Bead core 12 Bead Fillers 13 Cheha 14 Rim strip rubber 20 Sidewall 21 Sidewall rubber 30 tread 31 belt 32 Cap Ply 33 Tread Rubber 34 Tread Pattern 40 Carcass Ply 50 Inner Liner 60 sealant layer 70 Sound-absorbing layer 71 End 311 Belt 312 belt 331 Ground plane 341 Main groove 401 Main body 402 Bending section 403 Fold-over section 501 Inner self 601 Inner self 601a Medial facing area 601b Outer facing area 601c Non-opposed area

Claims

1. A pair of beads, A pair of sidewalls extending radially outward from each of the pair of beads, A tread having a contact surface is positioned between the pair of sidewalls, A carcass ply is stretched between the pair of beads, The inner liner is positioned on the inner side of the tire cavity of the carcass ply, A sealant layer is disposed on the inner surface of the inner liner on the inner side of the tire cavity, The sealant layer comprises a sound-absorbing layer disposed on the inner side of the tire cavity, The sealant layer is The region where the sealant layer and the sound-absorbing layer face each other is an inner opposing region which is a region in the tire axial direction that is inward from both ends of the sound-absorbing layer in the tire axial direction in the tire axial cross-section, The region where the sealant layer and the sound-absorbing layer face each other is an outer opposing region which, in a cross-section of the tire axis, is located further outward in the tire axis direction than the inner opposing region and further inward in the tire axis direction than both ends of the sound-absorbing layer, It has, A pneumatic tire in which the bonding force between the sealant layer and the sound-absorbing layer is higher in the outer opposing region than in the inner opposing region.

2. In the pneumatic tire described in claim 1, In the aforementioned outer opposing region, the sealant layer and the sound-absorbing layer are in adhesion. In the aforementioned inner opposing region, the sealant layer and the sound-absorbing layer are facing each other in a manner that allows for separation, in a pneumatic tire.

3. In the pneumatic tire according to claim 1 or claim 2, In the aforementioned outer opposing region, a portion of the sealant layer penetrates and engages with the void in the sound-absorbing layer. In the aforementioned inner opposing region, the sealant layer does not penetrate into the voids of the sound-absorbing layer, in a pneumatic tire.

4. In the pneumatic tire according to claim 1 or claim 2, A pneumatic tire in which the width in the tire axial direction of the outer opposing regions facing each other at both ends of the sound-absorbing layer is 10% or more and 30% or less of the width in the tire axial direction of the sound-absorbing layer.

5. In the pneumatic tire according to claim 1 or claim 2, A pneumatic tire in which the width in the tire axial direction of the outer opposing regions facing each other at both ends of the sound-absorbing layer is 10 mm or more and 20 mm or less, respectively.

6. In the pneumatic tire according to claim 1 or claim 2, The contact surface of the tread has at least one main groove that extends continuously along the circumferential direction of the tire. A pneumatic tire in which the sealant layer is positioned to be outward in the tire axial direction from all of the main grooves.

7. In the pneumatic tire according to claim 1 or claim 2, The tread comprises a belt disposed on the outer circumference side of the carcass ply, A pneumatic tire in which the sealant layer is positioned to be outward from the belt in the tire axial direction.

8. In the pneumatic tire according to claim 1 or claim 2, The sealant layer is positioned further outward in the tire axial direction than the outer opposing region and has non-opposing regions that do not face the sound-absorbing layer. A pneumatic tire in which the width in the axial direction of the non-opposing region is wider than the width in the axial direction of the outer opposing region.

9. A method for manufacturing a pneumatic tire according to claim 1 or claim 2, The steps include applying a sealant material to the region corresponding to the inner opposing region on the inner surface of the inner liner on the inner lumen side of the tire, The steps include: curing the sealant material applied to the region corresponding to the inner opposing region to form the inner opposing region; The steps include applying a sealant material to the area on the tire axial side of the inner opposing region on the inner surface of the inner liner on the inner cavity side of the tire, A method for manufacturing a pneumatic tire, comprising the steps of: placing the sound-absorbing layer on top of the sealant applied to the area axially outward of the inner opposing region, at least in part, before the sealant applied to the area axially outward of the inner opposing region hardens.

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