JP6502209B2 - Run flat tire - Google Patents

Description

  The present invention relates to run flat tires.

When a tire punctures while traveling, there is a run flat tire in which a sidewall portion is reinforced with side reinforcing rubber as a tire which can puncture a fixed distance.
As a run flat tire, for example, a color change material which irreversibly changes color due to a change in temperature is applied to the inner surface of the sidewall portion of the tire, thereby making it possible to determine the presence or absence of puncture travel history later Have been reported (e.g., Patent Document 1).

JP, 2013-132989, A

On the other hand, a run flat tire can be used after repairing a flat after run flat driving (punk driving). However, when running on a run flat, if the side reinforcement rubber receives a certain amount of heat or more, the side reinforcement rubber may be altered, so it is better to replace the tire itself than to do a simple puncture repair. desired.
However, it is difficult to visually determine whether or not the side reinforcing rubber has received a certain amount of heat during runflat running.
Further, for example, in the run flat tire of Patent Document 1, when the tire is bent and deformed due to run flat running, there is a risk that the applied color changing material may be peeled off at a portion where the bending deformation of the tire is severe. It is also assumed that the heat history of the bent and deformed portion can not be known with certainty.

  An object of this invention is to provide the run flat tire which can confirm the heat history of the side reinforcement rubber in run flat driving | running | working in consideration of the said matter.

<1> Sidewall portion connecting the tread portion and the bead portion, side reinforcing rubber disposed on the inner surface of the sidewall portion, and a region including the maximum bending portion on the inner surface side of the side reinforcing rubber A temperature flat member comprising a foamable material and a compressive strain absorbing material.

In the run flat tire according to <1>, a temperature indicating member having a compressive strain absorbing material and a thermosensitive foam material on the inner surface side of the side reinforcing rubber disposed on the inner surface of the sidewall portion connecting the tread portion and the bead portion. The temperature indicator is adhered to the inner surface of the side reinforcing rubber during normal driving. On the other hand, when the side reinforcing rubber formed on the inner surface of the sidewall portion is bent and deformed to raise the temperature, the volume of the heat-sensitive foamable material expands. The expansion of this volume causes all or part of the temperature indicating member to drop off or deform. Such falling-off is, for example, when the heat-sensitive foam material is present in the vicinity of the side reinforcing rubber in the temperature indication member, the temperature indication member and the side reinforcement rubber are expanded by the expansion of the volume of the heat-sensitive foam material. This is caused by a decrease in the adhesion area with the inner surface, or a decrease in the compressive strain absorbing ability of the temperature indicator.
Further, in the temperature-measuring member, when the heat-sensitive foam material is separated from the inner surface of the side reinforcing rubber, the portion containing the heat-sensitive foam material expands due to the expansion of the heat-sensitive foam material. The portion containing the heat-sensitive foam material may fall off or the portion may be deformed due to the decrease in the contact area between the portion and the other portion.
Therefore, even if the side reinforcing rubber is bent and deformed by run flat running, when the side reinforcing rubber does not rise to a certain temperature or more, the temperature indicating member is adhered to the inside of the side reinforcing rubber without being deformed. However, during run flat running, if the side reinforcing rubber is repeatedly bent significantly and the side reinforcing rubber reaches a certain temperature or more, all or part of the temperature measuring member falls off or deforms, so the side reinforcing rubber after run flat running The heat history of can be checked. Whether or not the side reinforcing rubber has deteriorated can be determined based on the heat history, that is, the degree of durability of the side reinforcing rubber, etc. can be determined, and effective information can be provided to determine whether the tire is repaired or punctured after puncture.

  Here, the temperature indicating member may be provided on the inner surface of the side reinforcing rubber. That is, although the temperature indicating member may be disposed directly on the side reinforcing rubber, when the inner liner is provided on the inner surface of the side reinforcing rubber, the inner side on the area including the maximum bending portion of the side reinforcing rubber. The temperature indicating member is disposed on the inner surface of the side reinforcing rubber through the liner.

  The run flat tire as described in <1> in which the <2> above-mentioned temperature indication member has a layer containing the said compressive-strain absorptive material and the said thermosensitive foamable material.

  <3> The temperature indicating member is a laminate in which the compression strain absorbing layer containing the compression strain absorbing material and the temperature indicating layer containing the thermosensitive foamable material are laminated in this order on the inner surface side of the side reinforcing rubber. The run flat tire as described in <1>.

  The run flat tire as described in any one of <1>-<3> in which the <4> above-mentioned compressive-strain absorptive material contains the adhesive agent of a silicone resin type.

  The run flat tire as described in any one of <1>-<4> whose heat conductivity of the <5> above-mentioned temperature indication member is 0.2 W / m * K or more.

<6> The temperature indicator member, run-flat tire according to any one of the elastic modulus is ^{1 × 10 6 Pa~1 × 10 10} Pa <1> ~ <5> at 25 ° C..

  The run flat tire as described in any one of <1>-<6> by which the <7> above-mentioned temperature indication member is multiply arranged.

  <8> The run flat tire according to <7>, wherein the plurality of temperature indicating members are arranged at an interval of 4 mm or more from each other in at least one of the tire circumferential direction and the tire radial direction.

  The area | region containing the <9> said largest bending part is an area | region within 80% of the length from the lower end of side reinforcement rubber to the upper end of side reinforcement rubber in the tire radial direction of the said side reinforcement rubber <1>-< The run flat tire as described in any one of 8>.

  The run flat tire as described in any one of <1>-<9> which the <10> above-mentioned heat-sensitive foamable material foams at the temperature of 80 degreeC-150 degreeC.

  ADVANTAGE OF THE INVENTION According to this invention, the run flat tire which can confirm the heat history of the side reinforcement rubber in run flat driving | running | working can be provided.

It is sectional drawing which shows the shape of the cross section which followed the tire width direction of the run flat tire which concerns on 1st Embodiment. It is sectional drawing which shows the change of the curvature radius in the largest bending part of the tire bent and deformed by a puncture. (A) shows the bending state of the tire at the time of normal driving | running | working, (B) shows the bending state of the tire at the time of run flat driving | running | working. It is sectional drawing which shows the temperature indication member in the tire of 1st Embodiment. (A) The schematic diagram which cut | disconnected the tire of 1st Embodiment along the tire peripheral direction, and observed the inner surface of the tire from the tire side side. (B) It is the perspective view which expanded a part of inner surface of the tire of 1st Embodiment.

The run flat tire according to the present invention includes a sidewall portion connecting the tread portion and the bead portion, a side reinforcing rubber disposed on the inner surface side of the sidewall portion, and a maximum bending portion on the inner surface side of the side reinforcing rubber. And a temperature indicating member disposed in the area and including a heat-sensitive foamable material and a compressive strain-absorbing material.
According to the run-flat tire of the present invention, the degree of durability and the like of the side reinforcing rubber can be determined by confirming the heat history of the side reinforcing rubber after run flat running (punk running).
"Confirmation" of the heat history means confirmation of "presence or absence or deformation" of the temperature sensing member. Moreover, as a confirmation method, a visual method as well as a tactile method is included.
Details will be described below.

First Embodiment
A run flat tire 10 according to a first embodiment will be described with reference to FIG. The present invention is not limited to the first embodiment.
FIG. 1 is a cross-sectional view showing the shape of the cross section along the tire width direction of the run flat tire according to the first embodiment. The arrow W in the figure indicates the width direction of the run flat tire 10, and the arrow R indicates the tire radial direction of the run flat tire 10. Further, a reference symbol CL indicates a center line passing through the center of the run flat tire 10 in the width direction.

The run flat tire 10 (hereinafter referred to as "tire 10") according to the first embodiment includes a pair of left and right bead portions 12 (only one bead portion 12 is shown in FIG. 1) and the pair of bead portions 12 A pair of bead cores 14 embedded in each, a carcass layer 16 extending in a toroidal shape between the pair of bead cores 14, a belt layer 18 provided radially outward of the carcass layer 16 from the carcass layer 16, and the belt layer A tread portion 20 provided radially outward of the tire 10 from 18, a sidewall portion 22 connecting the bead portion 12 and the tread portion 20, an inner liner 25 and a side formed on the inner surface of the sidewall portion 22 And a reinforcing rubber 26.
Further, the tire 10 may not have the inner liner 25. In this case, the temperature indicator 28 described later is directly adhered to the surface of the side reinforcing rubber 26. Therefore, the temperature indicating member 28 in the present invention is adhered to the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25.

  The carcass layer 16 is composed of one or more carcass plies. In the present embodiment, as an example, two carcass plies are provided. The carcass ply is formed by coating a plurality of cords (for example, organic fiber cords and metal cords) with a covering rubber. In addition, the carcass layer 16 has its end side folded back around the bead core 14 from the inside to the outside of the tire 10.

  The belt layer 18 is constituted by, for example, a plurality of belt plies (it may be constituted by one belt ply). The belt ply is formed by coating a plurality of cords (for example, organic fiber cords and metal cords) with a covering rubber.

  The tread portion 20 is formed with a plurality of circumferential grooves 24 extending in the circumferential direction of the tire 10. Further, in the tread portion 20, a plurality of width direction grooves (not shown) extending in a direction intersecting the circumferential direction are formed.

  A side reinforcing rubber 26 is installed on the inner side in the tire axial direction of the sidewall portion 22, and constitutes a part of the inner side wall of the tire 10. An inner liner 25 is provided on the inner side wall of the tire 10 including the inner side wall of the side reinforcing rubber 26. The upper end portion 26A of the side reinforcing rubber 26 extends to the tread portion 20, and the lower end portion 26B of the side reinforcing rubber 26 extends to the vicinity of the bead portion 12. In addition, the thickness of the side reinforcing rubber 26 becomes thinner toward the upper end portion 26A and the lower end portion 26B. Furthermore, the side reinforcing rubber 26 is formed of rubber harder than the rubber that constitutes the sidewall portion 22. Even if the tire 10 is punctured, the side reinforcing rubber 26 supports the weight of the vehicle and the occupant to run. It is configured to enable flat driving (punk driving).

The temperature indicating member 28 is disposed on the inner surface side of the side reinforcing rubber 26, that is, in the region 29 'including the maximum bending portion of the surface of the side reinforcing rubber 26 on the inner side in the tire axial direction (the inner side in the tire width direction). As described later, the temperature indicating member 28 includes a compressive strain absorbing material and a heat sensitive foamable material, and is disposed on the surface of the side reinforcing rubber 26. In the tire 10, the heat generated by the deflection generated around the maximum bending portion 29 of the side reinforcing rubber 26 is transmitted to the temperature indicating member 28. In addition, since the temperature sensing member 28 contains a compressive strain absorbing material, the maximum bending of the side reinforcing rubber 26 occurs even when normally traveling or run flat and the side reinforcing rubber 26 of the tire 10 is bent and deformed. When the region including the part does not rise to a predetermined temperature or more, the temperature indicator 28 is unlikely to be peeled off from the side reinforcing rubber 26 or the inner liner 25.
In the tire 10, when the run flat traveling is continued, the side reinforcing rubber 26 of the tire 10 is repeatedly and largely bent, thereby generating heat at a certain temperature or more around the maximum bending portion 29 of the side reinforcing rubber 26. The heat is transferred to the temperature indicator 28 disposed in the area 29 ′ including the maximum bending portion 29, and the heat-sensitive foamable material in the temperature indicator 28 expands to expand the temperature indicator 28. As a result of not being able to maintain the adhesion to the side reinforcing rubber 26, the temperature indicating member 28 is peeled off from the side reinforcing rubber 26 or the inner liner 25. For this reason, the heat history of the side reinforcing rubber 26 can be confirmed by the presence or absence of the temperature indicating member 28 after run-flat travel.

  In the first embodiment, the temperature indicating member 28 is disposed in the area 29 ′ including the maximum bending portion 29 of the inner surface of the side reinforcing rubber 26 of the tire 10.

Here, the “maximum bending portion” of the side reinforcing rubber means a portion where the bending of the side reinforcing rubber becomes maximum during run flat traveling. The maximum bending portion of the side reinforcing rubber is determined, for example, as follows. First, as shown in FIGS. 2A and 2B, in the cross section in the tire width direction, the innermost periphery of the tire is 0.5 cm apart from the side reinforcing rubber toward the bead portion 31 from the center (CL) in the tire width direction. Areas of fixed intervals demarcating the face are determined (in FIG. 2, each area is indicated by an area 35). Next, the amount of change in the radius of curvature due to bending in each of the regions 35 at a predetermined position from CL, ie, the radius of curvature (r1) in the tire (load 0 kN, internal pressure 200 kPa) during normal traveling in each region 35 The radius of curvature (r2) of the tire (load 8.5 kN, internal pressure 50 kPa) at the time of traveling is measured, and the amount of change (| r1-r2 |) is calculated.
By the above, on the inner surface of the side reinforcing rubber layer, the region 35 having the largest calculated variation is referred to as the maximum bending portion (see 32 in FIG. 2A and 33 in FIG. 2B).
The radius of curvature under each of the above conditions can be measured by image processing and measuring a cross-sectional image obtained by X-ray CT.

  As shown in FIGS. 2A and 2B, when the tire punctures, the side reinforcing rubber 26 is largely bent and deformed due to the load in the tire radial direction. In addition, since the tire 10 is rolling, the side reinforcing rubber 26 is repeatedly flexed and deformed continuously over the entire circumference. At this time, as shown in FIG. 2 (B), the largest bending portion 33 of the radius r2 is generated. In this case, the location of the maximum bending portion is often near the maximum width of the tire regardless of the tire diameter, and often occurs at a fixed position of the thickest portion of the side reinforcing rubber of the tire.

Next, the temperature indicator 28 will be described.
The temperature indicating member 28 of the first embodiment is disposed in a region (region 29 'in FIG. 1) including the largest bend of the surface of the side reinforcing rubber 26 formed on the inner surface of the sidewall portion.
FIG. 3 is a view showing a cross section of the temperature indicator. As shown in FIG. 3, the temperature indicator 28 disposed on the surface of the inner liner 25 has a layer containing a compressive strain absorbing material and a thermally expandable material.
The temperature indicator member 28 contains a compressive strain absorbing material, and absorbs compressive strain due to bending deformation from the side reinforcing rubber 26 until the tire starts to be largely bent by continuing the run flat running, and adheres to the surface of the inner liner 25. Keep doing.
After that, when the side reinforcing rubber 26 repeatedly starts to be largely bent and the temperature of the inner surface of the side reinforcing rubber 26 rises, the heat sensitive foamable material is ejected by heat, and the temperature indicating member 28 is rapidly expanded. As a result, the temperature indicating member 28 Can not continue to adhere and come off from the surface of the inner liner 25. The heat history after run flat traveling can be easily confirmed by the presence or absence of the dropout. In addition, even if the temperature-increasing member 28 does not drop off, it deforms to a large extent, so in this case as well, the heat history can be easily confirmed. The arrow H in FIG. 3 indicates the height of the temperature indicator 28, and the arrow L indicates the length of the temperature indicator 28 in the tire width direction.

  Moreover, an example of arrangement | positioning of the temperature indication member 28 is shown to (A) and (B) of FIG. FIG. 4A is a schematic view in which the tire 10 is cut along the circumferential direction of the tire and the inside of the tire 10 is observed from the side surface side of the tire 10. 4B is a perspective view in which a part of the inner surface of the tire 10 is enlarged. As shown in FIG. 4A, the temperature indicating member 28 is disposed on the inner surface of the side reinforcing rubber 26 via the inner liner 25. A plurality of temperature indication members 28 are arranged in a region including the maximum bending portion of the side reinforcing rubber 26 so as to be along the serration line 6 which is decorated in stripes along the tire radial direction on the inner surface of the tire 10. As shown in FIG. 4 (B), the temperature indicator 28 has a dome-shaped structure as a whole. When the temperature indicator 28 is observed from above, it has a circular shape as shown in FIGS. 4 (A) and 4 (B). However, the shape of the temperature display member 28 is not particularly limited. For example, the shape of the temperature display member 28 when observed from the upper side is circular (including oval), polygonal (for example, triangle, square, rhombus, It may be a pentagon, a hexagon, a star, etc.). Further, the overall shape of the temperature-measuring member 28 is not limited to the dome shape, and may be a conical shape such as a cylindrical shape, a prismatic shape, or a pyramid shape.

  Also, the temperature indicator 28 is disposed in a region including the maximum bending portion of the side reinforcing rubber 26. As a result, heat from the maximum bending portion of the side reinforcing rubber where the temperature is most raised by deformation of the tire is directly transmitted, while with respect to compression strain from the tire, the side reinforcing rubber is increased until the temperature rises. It can be made less susceptible to compressive strain due to bending of the rubber.

Here, the “region including the maximum bending portion” refers to the region including the maximum bending portion 29 on the inner surface of the tire 10 from the lower end of the side reinforcing rubber to the upper end of the side reinforcing rubber in the tire radial direction of the side reinforcing rubber. The length, that is, the area within at least 80% of the length from the side reinforcing rubber end 26A of FIG. 1 to the side reinforcing rubber end 26B.
Further, from the viewpoint of efficiently transmitting the heat from the maximum bending portion to the temperature-increasing member 28, the above-mentioned region is further preferably 50% or less, particularly preferably 30% or less.

The temperature measuring member 28 preferably has an elastic modulus at 25 ° C. of 1 × 10 ⁶ Pa to 1 × 10 ¹⁰ Pa. When the elastic modulus at 25 ° C. is 1 × 10 ⁶ Pa or more, the adhesion of the temperature-retaining member 28 to the side reinforcing rubber 26 or the inner liner 25 is enhanced, and by being 1 × 10 ¹⁰ Pa or less, the temperature-measuring member 28 is It is possible to further accelerate the drop-off during the expansion of the Further, the elastic modulus at 25 ° C., is preferably ^{1 × 10 7 Pa~1 × 10 9} Pa, particularly preferably ^{1 × 10 7 Pa~1 × 10 8} Pa.

  The elastic modulus of the temperature indicator 28 can be calculated using a universal compression tester. For example, a resin piece containing a thermosensitive foamable material and a compressive strain absorbing material constituting the temperature indicator is formed into a sheet of 3 cm × 1 cm × 50 μm by a known method, and the resulting sheet is measured by a viscoelasticity measuring device ( It can be measured at a test speed of 5 mm / min with Hitachi High-Tech Science DMS 7100), and a compressive stress-strain curve can be prepared from the measured values and calculated based on this.

  The compressive strain absorbing material is not particularly limited as long as it can absorb the bending deformation of the side reinforcing rubber 26 and has an adhesive force on the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25. Among them, from the viewpoint of a flexible adhesive having an appropriate elastic modulus and a small change in elastic modulus with respect to temperature, for example, polyolefin adhesives, chlorine rubber adhesives, acrylic adhesives [eg Y610 (Cemedine, Inc. Made of epoxy resin], epoxy-based adhesive [eg EP 138 (made by Cemedine), polyurethane-based adhesive [eg UM 700 (made by Cemedine)], nitrile rubber-based adhesive [eg Cemedine 521 (made by Cemedine)], vinyl chloride-based Adhesive [e.g. 201 (made by Cemedine)], vinyl acetate adhesive [e.g. 195 (made by Cemedine)], polyester-based adhesive [eg R820 (made by Cemedine)], phenolic adhesive [e.g. Metallock U-20 (for example, manufactured by Toyo Chemical Laboratory Co., Ltd.)], silicone resin adhesive [for example, KR-28 2, KR-311 (manufactured by Shin-Etsu Chemical Co., Ltd.)], modified silicone resin adhesives [for example, PM 100 (manufactured by Cemedine]), and the like. Among them, silicone resin adhesives and silicone resin adhesives and modified silicone resin adhesives are preferable, and among modified silicone resin adhesives, acrylic modified silicone resin adhesives are more preferable.

  Although the content rate (mass%) with respect to the thermogravimetric member 28 total mass of the said compressive-strain absorptive material which can be included in the thermochromic member 28 is suitably set, it is preferable that they are 10 mass%-95 mass%. By being 10% by mass or more, the adhesion between the temperature-increasing member 28 and the side reinforcing rubber 26 or the inner liner 25 can be more easily ensured at a temperature not higher than the temperature at which the temperature-increasing member 28 starts to expand. Thus, the temperature indicator 28 can be more reliably removed from the side reinforcing rubber 26 or the inner liner 25 when the temperature indicator 28 is expanded. Furthermore, it is more preferable that it is 40 mass%-90 mass%, and it is especially preferable that it is 50 mass%-80 mass%.

  The temperature indicator 28 may include a thermally conductive material in order to efficiently transfer the heat generated at the maximum bending portion 29 to the heat-sensitive foamable material when the tire 10 is bent and deformed. By including the thermally conductive material, it is possible to more reliably and efficiently transfer the heat due to the temperature increase of the maximum bending portion of the tire. From such a viewpoint, the thermal conductivity of the temperature indicator 28 is preferably 0.2 W / m · K or more, more preferably 0.5 W / m · K or more, and particularly preferably 1.5 W / m · K It is above.

Examples of the thermally conductive material include thermally conductive fillers. Examples of the thermally conductive filler include thermally conductive metal oxides, nitrides, metal powders, and carbides (carbon nanotubes, graphite, carbon fibers, etc.).
Examples of the metal oxide include aluminum oxide, magnesium oxide, zinc oxide, titanium oxide and silicon oxide. Examples of the nitride include boron nitride, aluminum nitride and silicon nitride. Examples of the carbide include silicon carbide and boron carbide. Examples of the metal powder include silver, gold, copper, and aluminum. As the heat conductive material, one or more of them can be used. As said heat conductive material, carbon, a carbon nanotube, a graphite, and a carbon fiber are preferable.

The temperature indication member 28 of the first embodiment includes a heat-sensitive foamable material that foams due to temperature change. The heat-sensitive foamable material means a material that foams by absorbing heat, and is a material that irreversibly expands the temperature-measuring member.
The heat-sensitive foamable material that foams due to temperature change is not particularly limited, and examples thereof include known heat-sensitive foamable materials. Among them, a heat-sensitive foamable material (hereinafter referred to as a thermally expandable microcapsule) which is microencapsulated is preferably mentioned.
The thermally expandable microcapsule is formed of, for example, a liquid foaming agent and a polymer shell containing the liquid foaming agent, and when heated, the polymer shell is softened and contained. As the blowing agent turns into gas, the pressure causes the capsule to expand to several tens to several hundreds of the previous volume. Therefore, by including a predetermined amount of such heat-sensitive foamable material in the temperature indicating member 28, the volume of the temperature indicating member 28 can be expanded by temperature rise. Thus, the shell of the polymer expanded by temperature is not particularly limited, and examples thereof include thermoplastic resins such as vinylidene chloride resins, acrylonitrile resins, and acrylic resins, among which acrylic resins are preferred. preferable.
As the foaming agent, various known inorganic foaming agents and organic foaming agents can be used. Moreover, a foaming agent can be used individually or in combination of 2 or more types.

As the thermally expandable microcapsule, for example, a microencapsulated thermal foaming agent described in JP-A-2013-79322 can be used.
The thermally expandable microcapsules may be commercially available ones and may be suitably prepared. As a preparation method, it describes in Unexamined-Japanese-Patent No. 2013-79322, for example. Moreover, as a commercially available product, for example, trade names “Matsumoto Microsphere F-36” “Matsumoto Microsphere F-36LV” “Matsumoto Microsphere F-48” “Matsumoto Microsphere FN-80 GS” “Matsumoto Microsphere F- 50 (manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.), and trade names "Expancel Microsphere WU" and "Exppancel Microsphere DU" (manufactured by Nippon Fillite Co., Ltd.).
The average particle diameter of the thermally expandable microcapsule is preferably 1 μm to 100 μm, and more preferably 3 μm to 50 μm from the viewpoint of dispersibility and thin layer formation.

  The content of the heat-sensitive foamable material relative to the total amount of the temperature-measuring member 28 is preferably 5% by mass to 90% by mass. By being 5 mass% or more, the thermal expansion property of the temperature indicator 28 can be enhanced, and the temperature can be more reliably caused to come off the inner surface of the side reinforcing rubber 26 of the temperature indicator 28 or the surface of the inner liner 25. . By being 90 mass% or less, sufficient adhesiveness with the side reinforcement rubber 26 or the inner liner 25 and more appropriate compression strain absorption capability can be ensured. Furthermore, the content is more preferably 10% by mass to 60% by mass, and particularly preferably 20% by mass to 50% by mass.

  Moreover, as a content rate with respect to the said compressive-strain absorptive material of the said thermosensitive foamable material, 5 mass%-90 mass% are preferable. By being 5 mass% or more, the thermal expansion property of the temperature indicator 28 can be enhanced, and the temperature can be more reliably caused to come off the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25. By being 90 mass% or less, sufficient adhesiveness with the side reinforcement rubber 26 or the inner liner 25 and more appropriate compressive strain absorption ability can be ensured. Furthermore, the content is more preferably 20% by mass to 80% by mass, and particularly preferably 30% by mass to 70% by mass.

  The volume when the temperature indicator 28 is expanded is appropriately adjusted. For example, the volume when the temperature indicator 28 is most expanded is 1.1 times to 3.0 times the volume of the temperature indicator 28 before expansion. Is preferred. The temperature indicator 28 can be more reliably removed from the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25 by being 1.1 times or more, and by 3.0 times or less, the temperature indicator 28 More reasonable compression strain absorption capacity is secured, and is more economical. The volume is more preferably 1.2 times to 2.5 times, and particularly preferably 1.5 times to 2.0 times.

  Further, the temperature at which the temperature indicator 28 is expanded can be adjusted by changing the type of the heat-sensitive foam material. The temperature at which the temperature-increasing member is expanded is appropriately adjusted according to the desired threshold value, but it is preferable to use a heat-sensitive foamable material that foams at an arbitrary temperature of 80 ° C. to 150 ° C. It is further preferable that the heat-sensitive foamable material foam at any temperature of 90 ° C to 140 ° C.

  As types of compressive strain absorbing materials and thermosensitive foamable materials contained in the temperature indicating member 28 and the content thereof, 10% by mass to 95% by mass of silicone resin based adhesive based on the total mass of the temperature indication member 28 and As the heat-sensitive foamable material, it is preferable to contain 5% by mass to 90% by mass of thermally expandable microcapsules having a shell of a thermoplastic polymer made of an acrylic resin and including a foaming agent. Furthermore, 10% by mass to 60% by mass of thermally expandable microcapsules containing a silicone resin adhesive at 40% by mass to 90% by mass and having a shell of a thermoplastic polymer consisting of an acrylic resin and including a foaming agent It is more preferable to contain%.

It is preferable that a plurality of temperature indicating members 28 be disposed on the inner surface of the side reinforcing rubber 26 or the surface of the inner liner. In this case, the plurality of temperature indicating members 28 can be provided to be aligned in the tire radial direction.
The thickness of the temperature-measuring member (see FIG. 3) is preferably 0.1 mm to 10 mm, more preferably 0.1 mm to 5 mm, from the viewpoint of adhesion and expansivity. Particularly preferred is 3 mm.

  In addition to the above-described materials, other components can be further added to the temperature indicator 28. The other components can be appropriately selected according to the purpose and necessity, and examples thereof include pressure-sensitive adhesives, coloring materials, pigments, binders, lubricants, known heat fusible substances, antioxidants, antistatic agents, etc. Be

  For example, the temperature-measuring member 28 kneads an additive such as an adhesive as the compressive strain-absorbing material, microbeads as a heat-sensitive foamable material, and an additive such as a binder using a revolution / revolution mixer etc. The flat tire side reinforcing rubber 26 is coated with a fixed area and a fixed thickness. Thereafter, the run-flat tire 10 having the temperature indicator 28 can be prepared by drying the run-flat tire at a temperature equal to or less than the temperature at which the expansion of the heat-sensitive foamable material starts.

An example of the arrangement position of the temperature indicator is shown in (A) and (B) of FIG. The plurality of temperature indicating members 28 disposed on the surface of the inner liner 25 are preferably disposed at a distance of 4 mm or more in at least one of the tire circumferential direction (C) and the tire radial direction (R). By setting the distance in at least one of the tire circumferential direction and the tire radial direction to 4 mm or more, it is possible to more reliably avoid contact with each other due to the plurality of temperature measuring members 28 being close to each other at the time of bending deformation of the tire. preferable. Further, by disposing a plurality of temperature-indicating members, temperature detection can be performed more accurately even with slight changes in the maximum bending site.
In the case where the temperature display members 28 are arranged in a plurality, a plurality of thermosensitive foamable materials may be used which foam in the same temperature range, or thermosensitive foamable materials which foam at different temperatures may be used. For example, by using a thermosensitive foam material that foams at a temperature range higher than that of the temperature indicating members arranged at a long distance, the temperature history of the plural temperature indicating members, that is, It is possible to know in detail the heat history of a wider range of side reinforcement rubber.

Next, the operation of the tire 10 of the first embodiment will be described.
When the tire 10 punctures while the vehicle is traveling, air (nitrogen) filled in the tire 10 leaks to the outside of the tire 10, and the air pressure of the tire 10 decreases.
The tire 10 in which air has leaked can be run-flat for a certain distance because the side reinforcing rubber 26 formed on the inner surface of the sidewall portion 22 supports the weight of the vehicle and the occupant.
During run-flat travel, the side reinforcing rubber 26 close to the tread portion 20 that is in contact with the road surface is largely bent and deformed due to the load in the tire radial direction. In addition, since the tire 10 is rolling, the side reinforcing rubber 26 is repeatedly flexed and deformed continuously over the entire circumference. Thereby, the hysteresis loss increases and the temperature of the side reinforcing rubber 26 rapidly rises. Such a phenomenon does not occur when the side reinforcing rubber 26 is bent several times, so it occurs only when the tire 10 is punctured.

  When the temperature of the side reinforcing rubber 26 rises and the surface temperature of the side reinforcing rubber 26 reaches, for example, 80 ° C. to 90 ° C., the temperature indicating member 28 disposed on the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25 In response to the heat transferred from the side reinforcing rubber 26, the expansion starts. Further, the side reinforcing rubber 26 generates heat by repeating bending deformation continuously. When the surface temperature of the side reinforcing rubber 26 is increased, the temperature indicator 28 can not maintain the adhesion between the temperature indicator 28 and the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25. Peel off. For this reason, even if the run-flat travel is finished and time passes, the heat history of the side reinforcing rubber 26 can be confirmed by the presence or absence of the temperature indicator 28.

  Here, since the temperature indicating member 28 disposed on the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25 contains a compressive strain absorbing material, until the side reinforcing rubber 26 is repeatedly bent to a large temperature, The temperature indicator 28 is unlikely to be missing from the inner surface of the side reinforcing rubber 26 or the surface of the inner liner 25.

  After run-flat traveling a fixed distance in the tire 10, the punctured tire 10 is removed from the rim, and it is confirmed whether or not the temperature indicating member 28 is present. Under the present circumstances, since it can be judged that temperature of side reinforcement rubber 26 has reached fixed temperature when temperature indicator 28 does not exist, it can be judged whether a tire can be repaired and it can be used. .

  For example, as a result of confirming the temperature indicating member 28, even though run-flat travel is performed, if the temperature indicating member 28 is present, the temperature of the side reinforcing rubber 26 does not reach a constant temperature. In this case, since the side reinforcing rubber 26 has not deteriorated, the tire 10 can be used again by repairing the punctured portion and filling it with air.

Conversely, if the temperature indicator 28 is not present, it means that the surface temperature of the side reinforcing rubber 26 has reached a certain temperature, and the side reinforcing rubber 26 may be degraded. It can be estimated that there is a fear that the strength is decreasing. In this case, the tire 10 is replaced with a new tire without being reused.
As described above, the heat history of the tire 10 can be determined by arranging the temperature indicating member 28 that expands with the temperature rise of the side reinforcing rubber 26.

Other Embodiments
As another embodiment, the temperature indicator is a laminate in which a compression strain absorbing layer containing a compression strain absorbing material and a temperature sensing layer containing a thermosensitive foam material are laminated in this order on the inner surface side of the side reinforcing rubber. It may be configured as it is. The compressive strain absorbing layer is a layer that absorbs compressive strain from the side reinforcing rubber 26, and the maximum bending portion of the surface on the inner side in the tire axial direction of the side reinforcing rubber 26 is the same as the temperature measuring member 28 of the first embodiment. It is arranged in the area 29 'including.
In addition, the temperature indicator refers to a layer showing a heat history due to temperature rise. The thermophilic layer receives heat from the side reinforcing rubber 26 through the compressive strain absorbing layer or the compressive strain absorbing layer and the inner liner 25 and expands when it rises above a certain temperature, causing a volume change, and then falling off or Or it deforms greatly. Therefore, the heat history can be confirmed by the presence or absence of the temperature indication layer or the presence or absence of deformation of the temperature indication layer. The thermophilic layer may be provided directly on the surface of the compressive strain absorbing layer, or another layer such as an adhesive layer may be further provided between the thermophilic layer and the compressive strain absorbing layer as long as the effects of the present invention are not affected. You may have.

As in the case of the temperature indicator described above, by forming the compression strain absorbing layer and the temperature indication layer in a separate layer configuration, desired functions can be easily provided in advance for each layer. That is, in the compressive strain absorbing layer, since it is not necessary to consider the influence by not including the thermosensitive foamable material etc. in the layer, the elastic modulus and the adhesive force necessary to maintain the compressive strain absorbing ability It is easy to preselect a compressive strain absorbing material etc. and set the necessary content so that Further, in the thermophilic layer, it is not necessary to consider the influence by not including the compressive strain absorbing material and the like in the layer, so that it is not necessary to consider the thermally expandable material and the like necessary to have the desired coefficient of thermal expansion. It is easy to select in advance and set the required content rate.
In addition, since the thermophilic layer is attached to the inner surface of the side reinforcing rubber 26 or the inner liner 25 via the compressive strain absorbing layer, the thermosensitive foam in the thermophilic layer is heated until the side reinforcing rubber rises to a certain temperature or higher. It is possible to prevent the foam material from foaming and to prevent the temperature sensing layer from falling off or being greatly deformed.

  The present invention will be specifically described by way of the following examples, but the present invention is not limited thereto.

Example 1
«Fabrication of test run flat tire»
The component shown to the following composition 1 was knead | mixed using the revolution mixer, and the mixture for temperature indicator preparation was obtained.
<Composition 1>
· Compression strain absorbing material: silicone modified acrylic resin (made by Cemedine) 66% by mass
Thermosensitive foamable material: Matsumoto Microsphere F-48 (manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) 33% by mass
Next, it is a run flat tire (size: 255 / 35R18) similar to the tire shown in the first embodiment, and is a region including the maximum bending portion on the inner side of the side reinforcing rubber, ie, the maximum bending portion on the inner liner The above mixture was applied to a region including the above using a mold or the like, and curing was performed at 23 ° C. for 24 hours to obtain a run flat tire having a dome-shaped temperature-measuring member with a diameter of 3 mm and a height of 1.5 mm.
Further, the temperature indicating members were arranged at an interval of 5 mm in the R direction (see FIG. 4B) in the region including the maximum bending portion on the inner liner.
As described above, the largest bend in the run flat tire is calculated as the absolute value of the variation between the curvature radius of the run flat tire during normal travel and the curvature radius of the run flat travel, and the largest value is calculated. It asked by specifying the place to have. Moreover, the curvature radius at the time of run flat driving | running | working was measured by image-processing and measuring the cross-sectional image obtained by X-ray CT (Y. MTIS, product made by YXLON).
«Run test»
The run flat tire having the temperature indicator member prepared above was mounted on a drum type running test machine, and running was performed under the following conditions.
<Condition>
· Tire internal pressure: 50kPa
・ Total load: 7 kN
・ Speed: 120km / h
Travel distance: 180 km
After run-flat traveling under the above conditions, the state of the temperature indicating member was confirmed.

(Example 2)
In Example 1, the presence or absence of a temperature indicating member was confirmed after traveling (normal traveling) in the same manner as in Example 1 except that the tire internal pressure of the conditions in the test method was changed to 260 kPa.

(Comparative example 1)
In Example 1, run flat running was performed in the same manner as in Example 1 except that the composition 1 of the mixture used for preparation of the temperature indicating member was changed to the following composition 2, and the state of the temperature indicating member was confirmed.
<Composition 2>
· Compression strain absorbing material: 100% by mass of silicone modified acrylic resin (made by Cemedine)
・ Heat-sensitive foamable material: None «Result»

From the results shown in Table 1, in Example 1, the temperature indication member was peeled off by run flat traveling, and in Example 2, the temperature indication member was not peeled off by normal traveling. For this reason, it was shown that, in a run flat tire equipped with a temperature indication member containing a heat-sensitive foamable material, the heat history of the side reinforcing rubber in run flat running can be confirmed by the presence or absence of the temperature indication member.
On the other hand, in Comparative Example 1, the temperature indicating member did not peel even by run flat traveling. For this reason, it was not possible to confirm the heat history of the side reinforcing rubber in run flat running in a run flat tire equipped with a temperature indicator not including a heat sensitive foam material.

DESCRIPTION OF SYMBOLS 10 run flat tire, 12, 31 bead part, 20 tread part, 22 sidewall part, 25 inner liner, 26 side reinforcement rubber, 28 temperature indication member, 29 maximum bending part, 29 'area including the maximum bending part, 35 area

Claims (10)

A sidewall portion connecting the tread portion and the bead portion;
A side reinforcing rubber disposed on the inner surface of the sidewall portion;
A temperature indicating member disposed in a region including the maximum bending portion on the inner surface side of the side reinforcing rubber, and including a heat sensitive foamable material and a compressive strain absorbing material;
Run flat tire with.   The run flat tire according to claim 1, wherein the temperature indicator has a layer including the compressive strain absorbing material and the heat-sensitive foamable material.   The thermosensitive member is a laminate in which a compressive strain absorbing layer containing the compressive strain absorbing material and a thermophilic layer containing the thermosensitive foamable material are laminated in this order on the inner surface side of the side reinforcing rubber. Run flat tire according to 1.   The run flat tire according to any one of claims 1 to 3, wherein the compressive strain absorbing material includes a silicone resin adhesive.   The run flat tire according to any one of claims 1 to 4, wherein a thermal conductivity of the temperature indicating member is 0.2 W / m · K or more. The run-flat tire according to any one of claims 1 to 5, wherein the temperature indicating member has an elastic modulus at 25 ° C of 1 × 10 ⁶ Pa to 1 × 10 ¹⁰ Pa.   The run flat tire according to any one of claims 1 to 6, wherein a plurality of the temperature indicating members are disposed.   The run flat tire according to claim 7, wherein the plurality of temperature indicating members are arranged at a distance of 4 mm or more from each other in at least one of the tire circumferential direction and the tire radial direction.   The area including the maximum bending portion is an area within 80% of the length from the lower end of the side reinforcing rubber to the upper end of the side reinforcing rubber in the tire radial direction of the side reinforcing rubber. The run flat tire according to any one of the items.   The run flat tire according to any one of claims 1 to 9, wherein the heat-sensitive foamable material foams at a temperature of 80 ° C to 150 ° C.