Tire with functional component

Abstract

To provide a tire which includes a storage body storing a functional component on a tire inner surface of a tread part, is excellent in sensing strength of a sensor function possessed by the functional component and insertion property of the functional component, prevents falling off of the functional component, and is excellent in durability of the storage body.SOLUTION: A tire with a functional component includes a storage body storing a functional component on a tire inner surface of a tread part, wherein the functional component has at least a contact surface contacting the tire inner surface and a sensor function for detecting tire information, the storage body is composed of a rubber component containing 50 mass% or more of natural rubber (NR), and 40 to 80 pts.mass of silica is contained with respect to 100 pts.mass of the rubber component.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tire having a functional component with a sensor function for detecting tire information provided on the inner surface of the tire.

Background Art

[0002] In order to detect tire information, a functional component having a sensor function (such as an electronic component such as a sensor unit) is disposed in a tire. In particular, due to ease of detecting air pressure and wear, the above-described functional component is disposed on the inner surface of the tread portion of the tire (for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, a container that houses a functional component disposed on the inner surface of the tread portion of the tire is likely to be subjected to forces due to the rotation of the tire during running and impacts from the road surface, and thus has problems in terms of durability. Patent Documents 1 and 2 disclose tires in which peeling from the tire surface of an electronic component mounting member (container) etc. hardly occurs even when a large impact is applied during high-speed running or during high-speed running in a low-temperature environment. However, these have limitations in the rubber physical properties of the members constituting the tire and the mounting position of the electronic component mounting member (container), and there is room for further improvement in terms of achieving both the durability of the container and the insertability and non-detachability (difficulty of detachment) of the functional component. In addition, this functional component is less likely to have a high sensing intensity of the sensor function due to the influence of the rotation of the tire during running, etc., and there is also room for further improvement in this regard.

[0005] Therefore, an object of the present invention is to provide a tire having a container housing functional components on the inner surface of the tread portion of the tire, excellent in the sensing intensity of the sensor function of the functional components and the insertability of the functional components, difficult for the functional components to fall off, and further excellent in the durability of the container.

Means for Solving the Problems

[0006] In order to solve the above problems, the present inventor has intensively studied and provided a container housing functional components on the inner surface of the tread portion of the tire. The functional components have at least a contact surface that contacts the inner surface of the tire and a sensor function for detecting tire information. The container is composed of a rubber component containing 50% by mass or more of natural rubber (NR), and further contains 40 to 80 parts by mass of silica with respect to 100 parts by mass of the rubber component. It has been found that such a tire has excellent sensing intensity of the sensor function of the functional components and excellent insertability of the functional components, is difficult for the functional components to fall off, and is further excellent in the durability of the container, and thus the present invention has been completed.

[0007] That is, the present invention is as follows <1> to <7>. <1>A tire comprising a container housing functional components on the inner surface of the tread portion of the tire, wherein the functional components have at least a contact surface that contacts the inner surface of the tire and a sensor function for detecting tire information, and the container is composed of a rubber component containing 50% by mass or more of natural rubber (NR), and further contains 40 to 80 parts by mass of silica with respect to 100 parts by mass of the rubber component. <2>The tire according to <1>, wherein the elongation at break (EB) of the container at 20°C is 150% or more and the tensile stress at 100% elongation (M100) at 100°C is 5.0 MPa or less. <3>The average value of the CTAB specific surface area of the silica is 130 m 2 / g or more, and the tire according to <1> or <2>. <4>The tire according to any one of <1> to <3>, wherein the rubber component contains butadiene rubber (BR). <5>The tire according to any one of <1> to <4>, wherein the container is fixed to the inner surface of the tire. <6>The tire according to <5>, wherein the container is fixed to the inner surface of the tire by an adhesive. <7>The tire according to any one of <1> to <6>, wherein the sensor function of the functional component is a sensor function using a piezoelectric element as a sensor element.

Advantages of the Invention

[0008] According to the present invention, a tire can be obtained that has a container housing a functional component on the inner surface of the tire in the tread portion, and the sensing intensity of the sensor function of this functional component and the insertability of this functional component are excellent, this functional component is difficult to fall off, and furthermore, the durability of this container is also excellent.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0010] The present invention will be described. The present invention provides a tire having a container on the inner surface of the tread portion for housing a functional component. This functional component has at least a contact surface that contacts the inner surface of the tire and a sensor function for detecting tire information. The container is made of a rubber component containing 50% by mass or more of natural rubber (NR), and further contains 40 to 80 parts by mass of silica per 100 parts by mass of this rubber component. Hereinafter, this will also be referred to as "the tire of the present invention".

[0011] In the present invention, the numerical range represented by "~" means a numerical range in which the numerical value described before "~" is the lower limit value and the numerical value described after "~" is the upper limit value, unless otherwise specified.

[0012] Hereinafter, the configuration, contained components and their contents of the container provided in the tire of the present invention, the configuration of the tire of the present invention (as a whole), etc. will be described in detail with reference to the drawings. Note that the dimensional ratios (length, thickness, etc.) and orientations of each member shown in the drawings may be different from the actual dimensional ratios and orientations in order to facilitate understanding of the invention. In addition, some may omit reference signs, etc.

[0013] [Container] The container provided in the tire of the present invention is made of a predetermined rubber component. The container is provided on the inner surface of the tread portion of the tire and houses a functional component having a sensor function for detecting tire information so as to have a contact surface that contacts the inner surface of the tire. For example, as shown in FIGS. 1 to 3, the base portion 31 of the container 30 is joined and fixed to the inner surface 12 of the tread portion 1 of the tire (the inner surface 12 joined to the base portion 31 is omitted in FIGS. 2 and 3). The accommodating portion 33 houses the functional component 20 so as to be surrounded by the side wall 32. Further, an embodiment is shown in which the accommodated functional component 20 has a contact surface 21 that contacts the inner surface 12 of the tread portion 1 via the base portion 31.

[0014] Here, the statement that the container is "provided on the inner surface of the tire in the tread portion" means that the container is connected and disposed on the inner surface of the tire in the tread portion (the inner circumferential surface of the tire at a position facing the tread surface of the tread portion). Further, the statement that the functional component has "a contact surface that contacts the inner surface of the tire (in the tread portion)" includes not only embodiments in which the functional component has a contact surface that directly contacts the inner surface of the tire in the tread portion, but also embodiments in which the functional component has a contact surface that contacts via a member (the base portion 31 in the embodiment of FIG. 1) that is in surface contact with the inner surface of the tire in the tread portion of the container. That is, embodiments in which the functional component is in direct surface contact with the inner surface of the tire in the tread portion, and embodiments in which the functional component is in surface contact via a member that is in surface contact with the inner surface of the tire in the tread portion of the container are included.

[0015] And it is more preferable that the container in which this functional component is housed is fixed to the inner surface of the tire in the tread portion (in a state where the position of the container does not substantially change), and further, it is more preferable that this is an embodiment in which the container is fixed to the inner surface of the tire in the tread portion by an adhesive. As this adhesive, an epoxy-based adhesive, an acrylic-based adhesive, or the like can be used. Also, a double-sided tape or the like may be used as the adhesive.

[0016] Hereinafter, details of each component included in this container and physical properties of this container will be described.

[0017] <Rubber component> The container provided in the tire of the present invention is composed of a rubber component containing 50% by mass or more of natural rubber (NR). That is, this container is composed of a rubber component, and this rubber component contains 50% by mass or more of natural rubber (NR). This rubber component is not particularly limited as long as it contains natural rubber (NR) at a content ratio of 50% by mass or more, and any known rubber component used (used in combination) for applications constituting rubber products such as diene rubbers can be used. Examples of diene rubbers include, in addition to the natural rubber (NR) described above, for example, butadiene rubber (BR), styrene-butadiene copolymer rubber (styrene-butadiene rubber, SBR), acrylonitrile-butadiene copolymer rubber (nitrile rubber, NBR), chloroprene rubber (CR), synthetic isoprene rubber (IR), styrene-isoprene copolymer rubber, isoprene-butadiene copolymer rubber, styrene-butadiene-vinylpyridine terpolymer (VP), and the like. Furthermore, it is also possible to use in combination rubber components other than diene rubbers such as olefin rubbers (ethylene-propylene rubber, acrylic rubber, etc.), fluororubbers, silicone rubbers, and butyl rubber (IIR). Also, as the butyl rubber (IIR), recycled butyl rubber obtained by recycling from used rubber products and the like can be used. In particular, when the rubber component constituting this container contains 50% by mass or more of natural rubber (NR) and contains butadiene rubber (BR) or butyl rubber (IIR), it is suitable because the effects of the present invention are more easily exhibited. When this rubber component contains 50% by mass or more of natural rubber (NR) and contains butadiene rubber (BR), it is more suitable from viewpoints such as achieving both an improvement in sensing strength and difficulty in dropping of functional parts.

[0018] In addition, the content ratio of natural rubber (NR) in the rubber component constituting the container provided in the tire of the present invention is more preferably more than 50% by mass, even more preferably 55% by mass or more, even more preferably 60% by mass or more, and may be 65% by mass or more, 70% by mass or more, 75% by mass or more, or 80% by mass or more, since the effects of the present invention are more likely to be exhibited. The upper limit may be 100% by mass, but is more preferably 95% by mass or less, even more preferably less than 90% by mass, and even more preferably 85% by mass or less. When the rubber component constituting the container provided in the tire of the present invention contains butyl rubber (IIR) or butadiene rubber (BR), the content ratio (the total content ratio when these are used in combination) is more preferably more than 10% by mass, even more preferably 15% by mass or more, and even more preferably 20% by mass or more. The upper limit is 50% by mass or less, but is more preferably 45% by mass or less, and even more preferably 40% by mass or less. The content ratio of butyl rubber (IIR) in the present invention is the content ratio of the entire butyl rubber including recycled butyl rubber (the same applies hereinafter).

[0019] Furthermore, when the rubber component constituting the container contains butyl rubber (IIR) or butadiene rubber (BR) in addition to natural rubber (NR), the effects of the present invention are more likely to be exerted. Therefore, in this rubber component, the content ratio of natural rubber (NR) is higher than the content ratio of butyl rubber (IIR) or butadiene rubber (BR) (when using them in combination, the total content ratio of these). It is more preferable that NR / (BR and / or IIR) is more than 1.0. Further preferably, the ratio of natural rubber (NR) to butyl rubber (IIR) or butadiene rubber (BR) in this rubber component is 1.5 times or more (NR / (BR and / or IIR) is 1.5 or more). Even more preferably, this ratio is 2 times or more (NR / (BR and / or IIR) is 2.0 or more), even more preferably 2.5 times or more (NR / (BR and / or IIR) is 2.5 or more), and even more preferably 3 times or more (NR / (BR and / or IIR) is 3.0 or more). The upper limit is not particularly limited, and it may be, for example, 20 times or less (NR / (BR and / or IIR) is 20 or less).

[0020] <Silica> The container provided in the tire of the present invention contains silica in addition to the above-described predetermined rubber component which is a constituent component. This silica is not particularly limited, and any known silica used in applications such as rubber products can be used. As specific examples of silica, for example, wet silica, dry silica, fumed silica, diatomaceous earth, etc. can be used. And this silica may be used alone or in combination of two or more. In addition, since it becomes easier to further improve the insertability of the functional parts and the durability of the container, the average value of the CTAB specific surface area of this silica is 130 m 2 / g or more is more preferable, 140 m 2 / g or more is even more preferable, 150 m 2 / g or more is even more preferable. That is, it is more suitable that the particle size of silica is smaller. The upper limit is more preferably 200 m 2 / g or less from the viewpoint of easily maintaining a high effect of suppressing the dropout of the functional parts, etc., and 180 m2 It is more preferably below / g.

[0021] Here, this "silica" means a particulate substance composed of silicon dioxide (SiO 2 2) or having silicon dioxide as a main component (for example, containing 80% by mass or more, more preferably 90% by mass or more). Also, the CTAB specific surface area of silica is a value measured according to "ISO5794 / 1". Furthermore, the "average value of the CTAB specific surface area of silica" is the value of the CTAB specific surface area of the silica when using one kind alone, and when using two or more kinds in combination, it is the value obtained by multiplying the value of the CTAB specific surface area of each silica used in combination by its usage ratio and adding them together. In this calculation, the total of the usage ratios of each silica is set to 1.0.

[0022] And in this container, the above-mentioned silica is contained in an amount of 40 to 80 parts by mass with respect to 100 parts by mass of the rubber component constituting the container. Furthermore, the content of this silica is more preferably 45 parts by mass or more, even more preferably 50 parts by mass or more, even more preferably 55 parts by mass or more, and even more preferably 60 parts by mass or more with respect to 100 parts by mass of the rubber component described above. The upper limit is more preferably 75 parts by mass or less, and even more preferably 70 parts by mass or less. Note that if the amount of this silica is less than 40 parts by mass or more than 80 parts by mass with respect to 100 parts by mass of the rubber component described above, the effects of the present invention (especially the durability of the container) may not be obtained. Here, the content of silica in the present invention means the total content of all silica when a plurality of silicas are included.

[0023] <Other components> The container provided in the tire of the present invention may further contain, as optional components, components other than the rubber component and silica described above, as long as it does not significantly affect the effects of the present invention. For example, carbon black, white fillers other than silica (talc, mica, clay, calcium carbonate, etc.), resin components (terpene resin, coumarone resin, indene resin, rosin resin, etc.), zinc oxide (zinc white), oil (aromatic oil, etc.), stearic acid, wax, lecithin, anti-aging agent, plasticizer, vulcanizing agent, vulcanization accelerator, vulcanization accelerator aid, and other various additives commonly used in rubber products can be contained in an appropriate amount. As the vulcanizing agent, sulfur is typically exemplified, but as a component other than sulfur, a compound having a cross-linking function between polymers such as peroxide may also be used. Further, these may be used in combination.

[0024] For example, the content of oil, wax, zinc oxide, and anti-aging agent in this container is preferably 0.5 to 10 parts by mass, and more preferably 1.0 to 8.0 parts by mass, based on 100 parts by mass of the rubber component constituting the container. And the content of sulfur in this container is preferably 1.0 to 5.0 parts by mass based on 100 parts by mass of the rubber component constituting the container. Further, the content of the vulcanization accelerator in this container is preferably 0.3 to 3.0 parts by mass, and more preferably 0.5 to 2.0 parts by mass, based on 100 parts by mass of the rubber component constituting the container, either with the primary accelerator alone or in a blend with the secondary accelerator.

[0025] In addition, in the container provided in the tire of the present invention, a silane coupling agent may be further contained in order to further improve the dispersibility of silica. This silane coupling agent is not particularly limited as long as it is a silane compound having a hydrolyzable group and an organic functional group. And this hydrolyzable group is not limited either, but for example, an alkoxy group, a phenoxy group, a carboxy group, an alkenyloxy group, etc. can be mentioned, and it is more preferable that the alkoxy group is an alkoxysilyl group bonded to a silicon atom. When the hydrolyzable group is an alkoxysilyl group, the carbon number of the alkoxy group is preferably 1 to 16, and more preferably 1 to 4. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, etc.

[0026] In addition, the organic functional group is not limited either, but it may be a group that can form a chemical bond with an organic compound. For example, an epoxy group, a vinyl group, an acryloyl group, a methacryl group, an amino group, a sulfide group (especially, a polysulfide group (-S n -: n is an integer of 2 or more)), a mercapto group, a blocked mercapto group (protected mercapto group) (for example, an octanoylthio group), etc. can be mentioned. Among them, a sulfide group (especially, a disulfide group, a tetrasulfide group), a mercapto group, and a blocked mercapto group are preferable. And such a silane coupling agent may be used alone or in combination of two or more.

[0027] And in this embodiment, it is preferable to contain 1 to 20 parts by mass of the silane coupling agent with respect to 100 parts by mass of silica, and more preferably 2 to 10 parts by mass.

[0028] <Elongation at break (EB) at 20°C and tensile stress at 100% elongation (M100) at 100°C> The container provided in the tire of the present invention has the above-described configuration. Further, it is more preferable that the elongation at break (EB) of this container at 20°C is 150% or more and the tensile stress at 100% elongation (M100) at 100°C is 5.0 MPa or less. This is because it is easy for the container and the like to have sufficient durability to withstand the forces and impacts caused by the rotation of the tire during running. This EB is more preferably 180% or more, further preferably 200% or more, further preferably 230% or more, further preferably 270% or more, and further preferably 300% or more. Also, this M100 is more preferably 4.9 MPa or less, further preferably 4.7 MPa or less, and further preferably 4.5 MPa or less. This lower limit is more preferably 1.0 MPa or more, further preferably 1.3 MPa or more, and further preferably 1.5 MPa or more because it becomes easier to further suppress the detachment of functional parts.

[0029] Here, this EB is a value confirmed by a method of collecting a predetermined rubber test piece (for example, dumbbell-shaped No. 7) from the container, performing a tensile test on this rubber test piece at a tensile speed of 500 mm / min in accordance with JIS K6251:2017, and measuring the elongation at break (elongation rate (%) at the time of cutting: EB) at 20°C. Also, this M100 is a value confirmed by a method of collecting a predetermined rubber test piece (for example, dumbbell-shaped No. 7) from the container, performing a tensile test on this rubber test piece at a tensile speed of 500 mm / min in accordance with JIS K6251:2017, and measuring the tensile stress at 100% elongation (MPa: M100) at 100°C. And within the range of the above-described configuration, this EB and M100 can be made within the above-described ranges by adjusting the ratio of each component, etc.

[0030] [Functional parts] As functional components to be accommodated in the tire accommodating body of the present invention, there are no particular limitations as long as they have a sensor function for detecting tire information and can have a contact surface that contacts the inner surface of the tread portion of the tire. For example, electronic components including various sensors, transmitters, receivers, control circuits, batteries, etc. are exemplified. Examples of tire information detected and acquired by the sensor function include the internal temperature and internal pressure (air pressure) of a pneumatic tire, the wear amount of the tread portion, etc. A temperature sensor or a pressure sensor can be used for measuring the internal temperature and internal pressure. For detecting the wear amount of the tread portion, a sensor element using a piezoelectric element is disposed on the contact surface, and a functional component that detects the output voltage corresponding to the tire deformation during running by the sensor element and detects the wear amount of the tread portion based on the output voltage is preferably exemplified. That is, when the sensor function of this functional component is a sensor function using a piezoelectric element as a sensor element, it is more preferable from the viewpoint of detecting the wear amount of the tread portion. In addition, it is also possible to use an acceleration sensor or a magnetic sensor.

[0031] [Tire] The tire of the present invention has, for example, a tread portion 1 that extends in the tire circumferential direction and forms an annular shape as shown in FIG. 1, and a pair of sidewall portions 2, 2 disposed on both sides of the tread portion 1 (both ends in the tire width direction), and an embodiment including a pair of bead portions 3, 3 disposed on the inner side in the tire radial direction of the pair of sidewall portions 2 is shown.

[0032] And in this embodiment, at least one carcass layer 4 is mounted between the pair of bead portions 3, 3. This carcass layer 4 includes a plurality of reinforcing cords extending in the tire radial direction, and is folded back from the inner side to the outer side of the tire around the bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition having a triangular cross section is disposed on the outer periphery of the bead core 5.

[0033] On one side, one or more (preferably multiple) belt layers 7 are arranged on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include a plurality of reinforcing cords inclined in substantially the same direction with respect to the tire circumferential direction (the reinforcing cords are embedded), and when including a plurality (for example, two layers) of belt layers 7, the reinforcing cords are arranged so as to cross each other between these layers. In the belt layer 7, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set, for example, in the range of 10° to 60° at the smaller angle. As the reinforcing cord of the belt layer 7, a steel cord is preferably used. On the outer peripheral side of the belt layer 7, for the purpose of improving high-speed durability, at least one belt cover layer 8 formed by arranging reinforcing cords at an angle of, for example, 5° or less with respect to the tire circumferential direction may be arranged. As the reinforcing cord of the belt cover layer 8, organic fiber cords such as nylon and aramid are preferably used.

[0034] Furthermore, a tread rubber layer 15 is arranged in the tread portion 1. The tread rubber layer 15 includes at least a cap tread rubber layer 15A. In this embodiment, it is composed of two layers, namely the cap tread rubber layer 15A forming the tread surface of the tread portion 1 and the under tread rubber layer 15B located on the inner side in the tire radial direction of the cap tread rubber layer 15A. Note that the tread rubber layer 15 may include a ground tread made of conductive rubber exposed on the tire contact surface and wing tips respectively arranged at both ends in the tire width direction of the cap tread rubber layer 15A.

[0035] The constituent components of the tire of the present invention (components constituting each member such as the tread portion and each layer such as the belt layer) are not particularly limited, and known components for constituting a tire such as rubber components can be arbitrarily used. Also, the tire size and the use of the tire are not particularly limited, and it is possible to make various tires such as passenger car tires, truck bus tires, and off-road tires.

[0036] The tire of the present invention is provided with a container having the above-described configuration on the inner surface of the tire of the tread portion of the tire in such an embodiment. The arrangement position of this container is not particularly limited as long as it is the inner surface of the tire of the tread portion, and it may be a position that does not pass through the center point in the tire width direction on the inner surface of the tire of the tread portion.

[0037] In addition, the tire of the present invention is preferably a pneumatic tire. As the gas filled in this pneumatic tire, for example, air, nitrogen, argon, an inert gas such as helium, and other gases can be used.

[0038] The tire (tire with functional parts) of the present invention having the above-described configuration has excellent sensing intensity of the sensor function of the functional parts provided on the inner surface of the tire of the tread portion, and the insertability of this functional part into the container is easy and it is difficult to fall off from the container. Furthermore, the durability of the container for housing this functional part is also excellent. That is, even if repeated deformation or the like occurs in the container due to rotation, deformation of the tread portion, impact, etc. during tire running, breakage (such as cracking or separation of members) of the container is less likely to occur.

[0039] Hereinafter, examples of the present invention will be described. However, the present invention is not limited to the following examples, and various modifications are possible within the technical idea of the present invention.

Example

[0040] (Fabrication and evaluation of tires with functional parts) Containers having the compositions shown in Table 1 below and the shapes shown in FIGS. 2 to 3 were fabricated, and these containers were bonded and fixed to the inner surface of the tread portion of a tire of tire size 235 / 50R17 96V with an adhesive as shown in FIG. 1. Furthermore, a functional part using a piezoelectric element as a sensor element was mounted on the container so that the piezoelectric element was arranged on the contact surface in contact with the inner surface of the above tire, and tires with various functional parts were fabricated.

[0041] Then, for the tires with functional components obtained in Reference Example 1, Comparative Examples 1-2, and Examples 1-8, the tensile stress at 100% elongation (M100) at 100 °C and the elongation at break (EB) at 20 °C of the receptacle were measured as follows, and the sensing strength of the functional components, the detachability (difficulty of detachment) of the functional components, the insertability of the functional components, and the durability of the receptacle were evaluated.

[0042] <Tensile stress at 100% elongation (M100) at 100 °C> From the accommodating part of the receptacle of each obtained tire with functional components, a dumbbell-shaped No. 7 rubber test piece (thickness 1.0 ± 0.1 mm) was taken, and for this rubber test piece, a tensile test was carried out at a tensile speed of 500 mm / min in accordance with JIS K6251:2017, and the tensile stress at 100% elongation (MPa: M100) was measured at 100 °C. This result was shown in the middle row of Table 1 below.

[0043] <Elongation at break (EB) at 20 °C> From the accommodating part of the receptacle of each obtained tire with functional components, a dumbbell-shaped No. 7 rubber test piece (thickness 1.0 ± 0.1 mm) was taken, and for this rubber test piece, a tensile test was carried out at a tensile speed of 500 mm / min in accordance with JIS K6251:2017, and the elongation at break (elongation rate at the time of cutting (%): EB) was measured at 20 °C. This result was shown in the middle row of Table 1 below.

[0044] <Sensing strength> For each obtained tire with functional components, it was assembled on a wheel with an air pressure of 230 kPa, and drum running was carried out at a speed of 30 km / h by a drum tester, and the peak height of the waveform detected by the sensor element of the functional component was measured. This result was shown in the lower row of Table 1 below. The results were expressed as an index with the value of Reference Example 1 being 100.

[0045] <Detachability of functional components> For each tire with the obtained functional components, it was assembled onto a wheel with an air pressure of 360 kPa and run on a drum tester. It was accelerated to a speed of 260 km / h in the first 10 minutes and then accelerated by 10 km / h every 10 minutes. Then, the speed at which the functional components fell off from the container was taken as the test result. This result was shown in the lower part of Table 1 below. The results are expressed as an index with the value of Reference Example 1 being 100, indicating that the larger the value, the more difficult it is for the components to fall off.

[0046] <Insertability of Functional Components> For each container joined and fixed to the inner surface of the tire, it was evaluated with ○× whether the same functional components could be inserted at once. This result was shown in the lower part of Table 1 below.

[0047] <Durability of Container> For each tire with the obtained functional components, as a pretreatment, oxygen was enclosed at 350 kPa and stored at 80 °C for 5 days. It was assembled onto a wheel and subjected to an indoor running test on a drum tester under the running conditions where the speed was increased by 10 km / h every 2 hours starting from 81 km / h. Then, the speed when the container was broken was taken as the test result. Note that the breakage of this container was defined as a state where the sensor function of the functional components could not be exerted due to cracks or detachment in the storage part of the container. This result was shown in the lower part of Table 1 below. The results were expressed as an index with the value of Reference Example 1 being 100.

[0048]

Table 1

[0049] The detailed contents of each component, etc. in Table 1 above are as follows. ·NR: Natural rubber (SIR20, manufactured by PT. PANTJA SURYA) ·BR: Butadiene rubber (Nipol BR1220, manufactured by Zeon Corporation, Japan) · IIR: Butyl rubber (EXXON Bromobutyl 2255, manufactured by ExxonMobil chemical company) · Silica 1: Silica (Zeosil 115GR, manufactured by solvay: CTAB specific surface area is 115 m 2 / g) · Silica 2: Silica (Zeosil 1165MP, manufactured by solvay: CTAB specific surface area is 160 m 2 / g) · Antioxidant: 6PPD (manufactured by Flexsys) · Wax: OZOACE-0015A (manufactured by Nippon Seiro Co., Ltd.) · Oil: Aroma oil (Diana Process NH-70S, manufactured by Idemitsu Kosan Co., Ltd.) · Zinc oxide: Zinc oxide (Silver Ridge R, manufactured by Toho Zinc Co., Ltd.) · Sulfur: Sulfax 5 (manufactured by Tsurumi Chemical Industry Co., Ltd.) · Vulcanization accelerator: Nocceler DM-PO (manufactured by Ouchi Shinko Chemical Industry Co., Ltd.)

[0050] From these results, in Examples 1 to 8 where the housing is composed of a rubber component containing 60% by mass or more of NR and further contains 60 to 75 parts by mass of silica with respect to 100 parts by mass of this rubber component, the sensing intensity of the sensor function, the drop-off property (difficulty of dropping off) of the functional parts, the insertability of the functional parts, and the durability of the housing were all improved. On the other hand, in Comparative Example 1 where the proportion of NR in the rubber component of the housing was low and Comparative Example 2 where the silica content was high, the durability of the housing was decreased in both cases. Also, in Comparative Example 2, the insertability of the functional parts was also decreased.

Explanation of symbols

[0051] 100 Tire 1 Tread part 2 Sidewall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 8 Belt cover layer 11 Tire circumferential groove Inner surface of the tire tread portion with 12 Functional components with 20 Contact surface (piezoelectric element) with 21 Container with 30 Base with 31 Side wall with 32 Receiving portion with 33

Claims

1. A tire comprising a container in which a functional component is housed on the inner surface of the tread portion of the tire, wherein the functional component has at least a contact surface that contacts the inner surface of the tire and a sensor function for detecting tire information, and the container is made of a rubber component containing 50% by mass or more of natural rubber (NR), and further contains 40 to 80 parts by mass of silica with respect to 100 parts by mass of the rubber component.

2. The tire according to claim 1, wherein the elongation at break (EB) of the container at 20°C is 150% or more and the tensile stress at 100% elongation (M100) at 100°C is 5.0 MPa or less.

3. The average value of the CTAB specific surface area of the silica is 130 m 2 / g or more, the tire according to claim 1 or 2.

4. The tire according to claim 1 or 2, wherein the rubber component contains butadiene rubber (BR).

5. The tire according to claim 1 or 2, wherein the container is fixed to the inner surface of the tire.

6. The tire according to claim 5, wherein the container is fixed to the inner surface of the tire by an adhesive.

7. The tire according to claim 1 or 2, wherein the sensor function of the functional component is a sensor function using a piezoelectric element as a sensor element.

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