Pneumatic tire, and method for manufacturing pneumatic tire

Abstract

To provide a pneumatic tire that can keep good sound suppression performance even during vehicle running in a cold district.SOLUTION: A pneumatic tire 1 comprises a tire main body 10 and a sound suppression material 30. The sound suppression material 30 is attached by an adhesion body 40 to a tire inner cavity surface 14a of the tire main body 10. In the pneumatic tire 1, a glass transition temperature of the adhesion body 40 is lower than a glass transition temperature of the sound suppression material 30.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pneumatic tire provided with a sound damping material.

Background Art

[0002] In a pneumatic tire mounted on a vehicle, cavity resonance occurs due to the air in the tire cavity as the vehicle travels. The sound generated by the cavity resonance of the tire is transmitted to the vehicle and becomes noise in the vehicle interior. Therefore, measures against tire cavity resonance have been taken to reduce it.

[0003] Patent Document 1 describes a pneumatic tire including a carcass extending from a tread portion through a sidewall portion to a bead core of a bead portion, a belt layer disposed radially outside the carcass and inside the tread portion, and a sound damping material disposed on the inner cavity surface of the tread portion, wherein the glass transition temperature of the sound damping material is -55°C to -45°C.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the pneumatic tire described in Patent Document 1, although the glass transition temperature of the sound damping material is mentioned, the glass transition temperature of the adhesive for attaching the sound damping material to the inner cavity surface of the tire is not considered. When the adhesive is damaged in a low-temperature environment, the sound damping material peels off from the inner cavity surface of the tire, generating abnormal noise. Further, the damaged adhesive floats inside the tire and may collide with the inner cavity surface of the tire, for example, causing damage.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a pneumatic tire capable of achieving good sound insulation performance even when traveling in cold regions.

Means for Solving the Problems

[0007] One aspect of the present invention is a pneumatic tire. The pneumatic tire includes a tire body and a sound insulation material attached to the inner cavity surface of the tire body by an adhesive, and is characterized in that the glass transition temperature of the adhesive is lower than the glass transition temperature of the sound insulation material.

Effects of the Invention

[0008] According to the present invention, good sound insulation performance can be achieved even when traveling in cold regions.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Modes for Carrying Out the Invention

[0010] Hereinafter, the present invention will be described based on preferred embodiments with reference to FIGS. 1 to 6. The same or equivalent components and members shown in each drawing are denoted by the same reference numerals, and repeated explanations will be omitted as appropriate. Also, the dimensions of the members in each drawing are appropriately enlarged or reduced for easy understanding. In addition, some of the members that are not important for explaining the embodiments in each drawing are omitted from the display.

[0011] (Embodiment) FIG. 1 is a cross-sectional view showing a longitudinal section of a pneumatic tire 1 including a sound damping material 30 according to an embodiment. The pneumatic tire 1 includes a tire body 10, a wheel 20, a sound damping material 30, and an adhesive 40. The tire body 10 contacts the ground by a tread portion 11 formed in a ring shape. Side portions 12 are continuously provided at both ends in the axial direction (the width direction of the tire) of the tread portion 11, and bead portions 13 are formed at the ends of the side portions 12 on the wheel 20 side.

[0012] A wheel 20 is fitted into the central portion of the tire body 10. The wheel 20 supports a rim portion 23 that forms a cylindrical shape with a disk portion 22 extending radially around a hub portion 21 that connects the axle. The bead portion 13 of the tire body 10 is fitted into the rim portion 23. The tire inner cavity 14 surrounded by the tire body 10 and the rim portion 23 is filled with air.

[0013] The sound damping material 30 is attached to the tire inner cavity surface 14a, which is the surface on the tire inner cavity 14 side of the tread portion 11, by an adhesive 40. The sound damping material 30 is a sponge formed of a foaming material, has a large number of pores, and is an open-cell foam having air permeability with the outside air. The sound damping material 30 is made of, for example, soft urethane foam, and has a density of 60 kg / m from the viewpoint of weight balance in the pneumatic tire 1. 3 The following are preferable, and the density is 40 kg / m. 3The following are more preferable. Also, from the perspective of durability, the sound deadening material 30 preferably has a tensile strength of 30 kPa or more and a tear strength of 2.0 N / cm or more (JIS K 6400-5). The sound deadening material 30 is disposed in a ring shape on the inner cavity surface 14a of the tire by at least one member. The sound deadening material 30 may be configured by two or more members to form a ring.

[0014] Figure 2 is a perspective view showing the appearance of the sound deadening material 30 disposed in the tire inner cavity 14. As described above, the sound deadening material 30 has a ring shape when disposed on the inner cavity surface 14a of the tire. Figure 2 also shows an adhesive body 40 for attaching the sound deadening material 30 to the inner cavity surface 14a of the tire. The sound deadening material 30 is attached by pressing it against the inner cavity surface 14a of the tire after applying the adhesive body 40 to the inner cavity surface 14a of the tire.

[0015] The adhesive body 40 extends in the circumferential direction and is formed linearly, and is applied to the inner cavity surface 14a of the tire in a ring shape as a whole. In Figure 2, three adhesive bodies 40 are provided. The number of the adhesive bodies 40 is not limited to the three shown, and two or more are sufficient. The outer peripheral surface 32 of the sound deadening material 30 is attached to the inner cavity surface 14a of the tire by the adhesive body 40, and the inner peripheral surface 31 faces the tire inner cavity 14. From the perspective of durability, it is preferable to use an adhesive having a shear adhesive strength of 0.1 MPa or more in JIS K 6850 for the adhesive body 40, and more preferably 0.3 MPa or more.

[0016] Before being disposed in the tire inner cavity 14, the sound deadening material 30 is in an elongated plate shape, and is deformed into a ring shape and attached to the inner cavity surface 14a of the tire. In a state where the sound deadening material 30 is attached to the inner cavity surface 14a of the tire, both ends in the circumferential direction of the sound deadening material 30 are butted against each other, and it is preferably joined by an adhesive body 41 to prevent wear due to rubbing of both ends.

[0017] Also, the longitudinal dimension of the outer peripheral surface 32 of the sound deadening material 30 is 100% or more and 105% or less of the inner circumferential length of the inner cavity surface 14a of the tire, so as to prevent a gap from occurring between the end faces when the sound deadening material 30 is attached to the inner cavity surface 14a of the tire.

[0018] Figure 3 is a cross-sectional view showing a longitudinal section of the tire body 10 and the adherend 40. On the tire inner cavity surface 14a of the tire body 10, at the time of molding, the strip portion 50 is formed by pressing a bladder against the tire inner cavity surface 14a. The strip portion 50 is formed in a convex or concave shape. In the example shown in FIG. 3, the strip portion 50 is provided so as to extend in a direction inclined with respect to the circumferential direction, and is formed on both sides with the axial center of the tire body 10 interposed therebetween. The strip portion 50 extends outward from a position closer to the axial center of the tire body 10 and is formed up to the bead portion 13. Further, the strip portion 50 may be provided so as to extend in a direction orthogonal to the circumferential direction.

[0019] The adherend 40 extends in the circumferential direction as described above and intersects the strip portion 50. FIG. 4 is a cross-sectional view of the pneumatic tire 1 taken along line A-A shown in FIG. 3. In FIG. 4, cross-sections of the tire body 10, the sound deadening material 30, and the adherend 40 are shown. Also, the line A-A shown in FIG. 3 is a line segment extending in the circumferential direction at a position including the adherend 40.

[0020] As shown in FIG. 4, the adherend 40 is applied between the convex strip portion 50 and between the strip portions 50, and the sound deadening material 30 is attached and fixed to the tire inner cavity surface 14a. The thickness of the adherend 40 becomes thinner at the convex strip portion 50 and thicker between the strip portions 50. When the strip portion 50 is formed in a concave shape, the thickness of the adherend 40 becomes thicker at the concave strip portion 50 and thinner between the strip portions 50.

[0021] The sound deadening material 30 is fixed to the inner cavity surface 14a of the tire by the adhesive 40. After the adhesion is completed by drying and curing, etc., the glass transition temperature of the adhesive 40 is set to a value lower than the glass transition temperature of the sound deadening material 30. Incidentally, regarding the glass transition temperatures of the adhesive 40 and the sound deadening material 30, as an example, the glass transition temperature of the adhesive 40 may be -130°C or higher and -70°C or lower (by the DMA method which is a dynamic viscoelasticity measurement), and the glass transition temperature of the sound deadening material 30 may be -60°C or higher and -45°C or lower (by the DSC method which is a differential scanning calorimetry measurement). The adhesive 40 may be one with a small change in the glass transition temperature before and after curing, or one that becomes lower than the glass transition temperature of the sound deadening material 30 even if the glass transition temperature changes after curing.

[0022] Next, the operation of the pneumatic tire 1 will be described by focusing on the sound deadening material 30 and the adhesive 40. When a vehicle equipped with the pneumatic tire 1 is running, the cavity resonance generated in the tire inner cavity 14 is absorbed by the sound deadening material 30 and dissipated as heat energy, reducing the noise in the pneumatic tire 1. In cold regions, if the glass transition temperatures of the sound deadening material 30 and the adhesive 40 are high, these members will undergo glass transition and be damaged. The glass transition temperatures of the sound deadening material 30 and the adhesive 40 in this embodiment are set low, and the sound deadening performance by the sound deadening material 30 is maintained well even during running in cold regions.

[0023] The glass transition temperature of the adhesive 40 is set to a value lower than the glass transition temperature of the sound deadening material 30. When the temperature decreases, it is suppressed that the adhesive 40 undergoes glass transition and is damaged before the sound deadening material 30. If the adhesive 40 is damaged before the sound deadening material 30, concerns such as peeling of the sound deadening material 30 from the inner cavity surface 14a of the tire, wear due to vibration of the sound deadening material 30 after peeling, and damage to the inner cavity surface 14a of the tire by fragments of the glass-transitioned adhesive 40 are raised. In this embodiment, since the glass transition temperature of the adhesive 40 is set to a value lower than the glass transition temperature of the sound deadening material 30, it is possible to suppress peeling of the sound deadening material 30, wear of the sound deadening material 30, and damage to the inner cavity surface 14a of the tire by fragments of the adhesive 40.

[0024] The pneumatic tire 1 forms the strip portion 50 by pressing the bladder against the inner cavity surface 14a of the tire during molding. When the strip portion 50 and the adhesive body 40 intersect, as described above, the thickness of the adhesive body 40 changes between the strip portion 50 and the strip portion 50. When the glass transition temperature of the adhesive body 40 is higher than that of the sound deadening material 30, during driving in a cold region, if the adhesive body 40 reaches the glass transition temperature earlier than the sound deadening material 30, due to the change in the thickness of the adhesive body 40, local stress concentration occurs and the damage of the adhesive body 40 tends to progress.

[0025] In the present embodiment, since the glass transition temperature of the adhesive body 40 is set lower than that of the sound deadening material 30, at least the adhesive body 40 can be prevented from reaching the glass transition temperature earlier than the sound deadening material 30 and the damage of the adhesive body 40 due to stress concentration from progressing. Incidentally, the strip portion 50 is provided on the inner cavity surface 14a of the tire body 10 so as to be inclined or orthogonal to the circumferential direction, whereby the peeling of the bladder during molding can be facilitated. However, all of them intersect with the adhesive body 40 extending in the circumferential direction, and the thickness of the adhesive body 40 will change.

[0026] The adhesive body 40 is provided linearly extending in the circumferential direction of the tire body 10, and the adhesion process can be simplified and the influence on the tire weight can be reduced. Since the glass transition temperature of the adhesive body 40 in the pneumatic tire 1 is set lower than that of the sound deadening material 30, at least the adhesive body 40 can be prevented from reaching the glass transition temperature earlier than the sound deadening material 30 and fragments of the linear adhesive body 40 from being generated.

[0027] (Modification example) FIG. 5 is a schematic view showing the strip portion 50 of the inner cavity surface 14a of the tire according to the modification example. The strip portion 50 has a main strip portion 51 extending in a direction inclined in the circumferential direction of the tire body 10, and a plurality of sub-strip portions 52 formed in a concave or convex mesh pattern between the main strip portions 51. The sub-strip portion 52 is formed by providing a large number of convex or concave portions of the same size on the surface of the bladder pressed against the inner cavity surface 14a of the tire during molding.

[0028] FIG. 6 is a cross-sectional view of the pneumatic tire 1 taken along line B-B shown in FIG. 5. As shown in FIG. 4, the adhesive 40 is applied between the convex main ribs 51 and sub-ribs 52 and between each rib, and the sound deadening material 30 is attached and fixed to the inner cavity surface 14a of the tire. The thickness of the adhesive 40 is thinner at the convex main ribs 51 and sub-ribs 52 and thicker between each rib. As shown in this modification, a part of the sub-ribs 52 formed in a mesh shape intersects with the adhesive 40 provided to extend linearly in the circumferential direction, and it is considered to be equivalent to the relationship in which the rib 50 and the adhesive 40 intersect described in the above embodiment.

[0029] Next, the features of the pneumatic tire 1 according to the embodiment and the modification will be described. The pneumatic tire 1 includes a tire body 10 and a sound deadening material 30. The sound deadening material 30 is attached to the inner cavity surface 14a of the tire body 10 by an adhesive 40. The pneumatic tire 1 has a glass transition temperature of the adhesive 40 lower than that of the sound deadening material 30. Thereby, in the pneumatic tire 1, when traveling in a cold region, it is possible to suppress the adhesive 40 from reaching the glass transition temperature and being damaged earlier than at least the sound deadening material 30, and the sound deadening performance can be improved.

[0030] Also, the adhesive 40 extends in the circumferential direction of the tire body 10 and is provided linearly on the inner cavity surface 14a of the tire. Thereby, the pneumatic tire 1 can simplify the adhesion process and reduce the influence on the tire weight.

[0031] Further, the tire body 10 has convex or concave ribs 50 formed by pressing a bladder against the inner cavity surface 14a during molding. The adhesive 40 intersects the rib 50. Thereby, although the thickness of the adhesive changes and stress concentration is likely to occur in the pneumatic tire 1, it is possible to suppress the adhesive 40 from reaching the glass transition temperature and being damaged earlier than at least the sound deadening material 30, and the sound deadening performance can be improved.

[0032] Further, the strip portion 50 is inclined with respect to the circumferential direction of the tire body 10. Thereby, the bladder can be easily peeled off during the molding of the pneumatic tire 1.

[0033] As described above, the embodiments of the present invention have been described. These embodiments are illustrative, and it is understood by those skilled in the art that various modifications and changes are possible within the scope of the claims of the present invention, and such modifications and changes are also within the scope of the claims of the present invention. Therefore, the descriptions and drawings in this specification should be treated as illustrative rather than restrictive.

Explanation of reference numerals

[0034] 1 Pneumatic tire, 10 Tire body, 14a Tire inner cavity surface (inner cavity surface), 30 Sound deadening material, 40 Adhesive, 50 Strip portion.

Claims

1. A tire body, a sound deadening material which is attached to the inner cavity surface of the tire body by an adhesive having a shear adhesion strength of 0.1 MPa or more according to JIS K 6850 and a glass transition temperature of -60°C or more and -45°C or less, and an inflated tire, characterized in that the glass transition temperature of the adhesive is lower than the glass transition temperature of the sound deadening material.

2. The inflated tire according to claim 1, characterized in that the adhesive extends in the circumferential direction of the tire body and is linearly provided on the inner cavity surface.

3. The tire body has convex or concave strip portions formed by pressing a bladder against the inner cavity surface during molding, and the inflated tire according to claim 2, characterized in that the adhesive intersects the strip portions.

4. The inflated tire according to claim 3, characterized in that the strip portions are inclined with respect to the circumferential direction.

5. A method for manufacturing an inflated tire having a tire body, a sound deadening material, and an adhesive for bonding the tire body and the sound deadening material, comprising: a step of forming at least convex or concave strip portions formed by pressing a bladder against the inner cavity surface of the tire body during molding of the tire body; a step of applying an adhesive having a shear adhesion strength of 0.1 MPa or more according to JIS K 6850 to the inner cavity surface so as to intersect the strip portions; a step of attaching the sound deadening material by pressing it against the inner cavity surface; and the glass transition temperature of the sound deadening material is -60°C or more and -45°C or less, a method for manufacturing an inflated tire, characterized in that the glass transition temperature of the adhesive is lower than the glass transition temperature of the sound deadening material.

6. The method for manufacturing an inflated tire according to claim 5, characterized in that the strip portions are inclined with respect to the circumferential direction of the tire body.

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