tire

Abstract

To provide a tire which uses thermoplastic elastomer and is excellent in stability.SOLUTION: A tire has a tread part and a side wall part which are formed of thermoplastic elastomer composition. A deviation A in a tire radial direction on an outermost surface of a tread crown part satisfies an expression (1) when a prescribed air pressure is filled after performing normal rim assembly: A≤3.0% ...(1). A total thickness T (mm) of the tread crown part and an outer diameter Dt (mm) of the tire satisfy an expression (2): T / Dt≤0.034 ...(2).<Prescribed air pressure> In a case that a virtual volume V of the tire is 15000 cm3 or more: 250 (kPa). In a case that the virtual volume V of the tire is less than 15000 cm3: 0.0152×V+22.553 (kPa). The virtual volume V (mm3) of the tire is calculated based on an outer diameter Dt (mm) of the tire, a sectional width Wt (mm), a cross section height H (mm) when the normal rim assembly is performed and an inner pressure is air pressure: V={(Dt / 2)2-(R / 2)2}×π×Wt; and R=Dt-2H.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a tire.

Background Art

[0002] Tires generally have a vulcanized rubber composition occupying most of their components. Since the vulcanized rubber composition is difficult to recycle, tires using, for example, thermoplastic elastomers have been studied to improve recyclability. However, there are few examples of commercializing tires using the above thermoplastic elastomers, and there are still problems to be solved for commercialization at present.

Summary of the Invention

Problems to be Solved by the Invention

[0003] An object of the present disclosure is to solve the above problems and provide a tire using a thermoplastic elastomer that has excellent handling stability.

Means for Solving the Problems

[0004] The present disclosure is a tire in which a tread portion and a sidewall portion are formed from a thermoplastic elastomer composition, when filled with the following predetermined air pressure after rim assembly on a regular rim, the displacement A in the tire radial direction on the outermost surface of the tread crown portion satisfies the following formula (1), (1) A ≦ 3.0% relates to a tire in which the total thickness T (mm) in the tread crown portion and the outer diameter Dt (mm) of the tire satisfy the following formula (2). (2) T / Dt ≦ 0.034 <Predetermined air pressure> When the virtual volume V of the tire is 15000 cm 3 or more: 250 (kPa) When the virtual volume V of the tire is less than 15000 cm 3 : 0.0152 × V + 22.553 (kPa) Note that the virtual volume V of the tire (mm 3) is a value calculated by the following formula using the outer diameter Dt (mm) of the tire, the section width Wt (mm) of the tire, the rim diameter R (mm), and the section height H (mm) of the tire. V = {(Dt / 2) 2 - (R / 2) 2} × π × Wt R = Dt - 2H (In the formula, Dt, Wt, and H are all values in a state where the tire is assembled on a standard rim and the internal pressure is atmospheric pressure.)

Advantages of the Invention

[0005] According to the present disclosure, since the tread portion and the sidewall portion are formed from a thermoplastic elastomer composition and the tire satisfies the above formulas (1) and (2), a tire excellent in handling stability can be provided.

Brief Description of the Drawings

[0006] [Figure 1] A cross-sectional view showing a part of the pneumatic tire 2. [Figure 2] An enlarged cross-sectional view showing the vicinity of the tread portion 4 of the tire 2 in FIG. 1.

Modes for Carrying Out the Invention

[0007] The tire of the present disclosure has a tread portion and a sidewall portion formed from a thermoplastic elastomer composition and satisfies the above formulas (1) and (2).

[0008] Although the mechanism by which the above effects are obtained is not clear, it is presumed as follows. When a slightly high internal pressure during actual use is applied, since the amount of deformation is 3.0% or less (formula (1)), the amount of deformation during the rolling of the tread portion can be reduced, and the heat generation associated therewith can be reduced. Therefore, plasticization of each member of the thermoplastic elastomer can be suppressed, good responsiveness can be obtained, and it is considered that the handling stability is improved. Also, by setting the ratio of the total thickness of the tread crown portion to the tire outer diameter to a predetermined value or less (Equation (2)), heat inside the tire can be easily released from the tread portion, heat accumulation in the tread portion can be suppressed, and furthermore, plasticization of the entire tire can be easily suppressed, resulting in good handling stability. Therefore, it is presumed that a tire formed with a thermoplastic elastomer composition for the tread portion and the sidewall portion and satisfying the above-described Equations (1) and (2) is excellent in handling stability.

[0009] Thus, the tire is a tire in which the tread portion and the sidewall portion are formed of a thermoplastic elastomer composition, and by configuring the tire to have the following equations: Equation (1) “A ≤ 3.0%” and Equation (2) “T / Dt ≤ 0.034”, the problem (objective) of imparting excellent handling stability is solved. That is, the configurations of Equation (1) “A ≤ 3%” and Equation (2) “T / Dt ≤ 0.034” do not define the problem (objective). The problem of the present application is to impart excellent handling stability, and the solution means therefor is to configure to satisfy the parameters.

[0010] When the tire is mounted on a standard rim and filled with the following predetermined air pressure, the displacement A in the tire radial direction at the outermost surface of the tread crown portion satisfies the following Equation (1). (1) A ≤ 3.0% <Predetermined air pressure> When the virtual volume V of the tire is 15000 cm 3 or more: 250 (kPa) When the virtual volume V of the tire is less than 15000 cm 3 : 0.0152 × V + 22.553 (kPa) Note that the virtual volume V (mm 3 ) of the tire is a value calculated by the following equation using the outer diameter Dt (mm) of the tire, the cross-sectional width Wt (mm) of the tire, the rim diameter R (mm), and the cross-sectional height H (mm) of the tire. V = {(Dt / 2) 2 - (R / 2) 2} × π × Wt R = Dt - 2H (In the formula, Dt, Wt, and H are all values ​​obtained when the tire is mounted on a standard rim and the internal pressure is equal to atmospheric pressure.)

[0011] A can be set appropriately depending on the tire's application, but is preferably 12.0% or less, more preferably 5.0% or less, even more preferably 1.5% or less, and particularly preferably 1.0% or less. The lower limit is preferably 0.1% or more, more preferably 0.2% or more, and even more preferably 0.3% or more. Within the above range, a better effect tends to be obtained.

[0012] For passenger car tires, A is preferably 5.0% or less, more preferably 1.5% or less, even more preferably 1.0% or less, and particularly preferably 0.5% or less. The lower limit is preferably 0.1% or more, more preferably 0.2% or more, and even more preferably 0.3% or more. Within the above range, a better effect tends to be obtained.

[0013] For racing tires (such as kart tires), A is preferably 12.0% or less, more preferably 2.0% or less, even more preferably 1.5% or less, and particularly preferably 1.2% or less. The lower limit is preferably 0.1% or more, more preferably 0.2% or more, and even more preferably 0.3% or more. Within the above range, better effects tend to be obtained.

[0014] From the viewpoint of obtaining better performance, it is desirable that the virtual volume V of the tire satisfies the following equation. V≧4000cm 3 V can be set appropriately depending on the tire's intended use, but preferably 5000 cm. 3 More preferably 10,000 cm 3 More preferably 20,000 cm 3 That is all. The upper limit is preferably 450,000 cm. 3 More precisely, 42,000 cm 3 Further preferably 40,000 cm 3The following applies. Within the above range, better results tend to be obtained.

[0015] For passenger car tires, V is preferably 20,000 cm 3 More preferably 30,000 cm 3 More preferably 32,000 cm² 3 In particular, 37698cm is preferred. 3 That is all. The upper limit is preferably 450,000 cm. 3 More precisely, 42,000 cm 3 Further preferably 40,000 cm 3 The following applies. Within the above range, better results tend to be obtained.

[0016] For racing tires (such as karting tires), V is preferably 4500 cm². 3 More preferably 4800 cm 3 More preferably 5000 cm 3 In particular, 5108 cm is preferred. 3 That is all. The upper limit is preferably 10,000 cm. 3 More specifically, 7000 cm 3 Further preferably, 6000 cm 3 The following applies. Within the above range, better results tend to be obtained.

[0017] From the viewpoint of obtaining better performance, it is desirable that the outer diameter Dt of the tire satisfies the following formula. Dt≧200mm Dt can be set appropriately depending on the tire's application, but is preferably 250mm or more, more preferably 350mm or more, even more preferably 450mm or more, and particularly preferably 550mm or more. The upper limit is preferably 800mm or less, more preferably 700mm or less, even more preferably 670mm or less, and particularly preferably 650mm or less. Within the above range, a better effect tends to be obtained.

[0018] For passenger car tires, Dt is preferably 550 mm or more, more preferably 600 mm or more, even more preferably 620 mm or more, particularly preferably 630 mm or more, and most preferably 632 mm or more. The upper limit is preferably 750 mm or less, more preferably 700 mm or less, even more preferably 680 mm or less, and particularly preferably 670 mm or less. Within the above range, a better effect tends to be obtained.

[0019] For racing tires (such as kart tires), Dt is preferably 220 mm or more, more preferably 230 mm or more, even more preferably 240 mm or more, particularly preferably 250 mm or more, and most preferably 255 mm or more. The upper limit is preferably 350 mm or less, more preferably 300 mm or less, even more preferably 280 mm or less, and particularly preferably 270 mm or less. Within the above range, a better effect tends to be obtained.

[0020] From the viewpoint of obtaining better performance, it is desirable that the tire's cross-sectional width Wt satisfies the following formula. Wt≧100mm Wt can be set appropriately depending on the tire's application, but is preferably 120mm or more, more preferably 125mm or more, and even more preferably 130mm or more. The upper limit is preferably 250mm or less, more preferably 230mm or less, and even more preferably 210mm or less. Within the above range, better performance tends to be obtained.

[0021] For passenger car tires, Wt is preferably 150 mm or more, more preferably 180 mm or more, even more preferably 200 mm or more, and particularly preferably 205 mm or more. The upper limit is preferably 250 mm or less, more preferably 230 mm or less, and even more preferably 210 mm or less. Within the above range, better effects tend to be obtained.

[0022] For racing tires (such as kart tires), the Wt is preferably 120 mm or more, more preferably 125 mm or more, even more preferably 130 mm or more, and particularly preferably 133 mm or more. The upper limit is preferably 200 mm or less, more preferably 170 mm or less, and even more preferably 150 mm or less. Within the above range, better performance tends to be obtained.

[0023] From the viewpoint of obtaining better performance, it is desirable that the tire's cross-sectional height H satisfies the following formula. H≧50mm H can be set appropriately depending on the tire's application, but is preferably 80mm or more, more preferably 90mm or more, even more preferably 100mm or more, and particularly preferably 110mm or more. The upper limit is preferably 180mm or less, more preferably 160mm or less, even more preferably 140mm or less, and particularly preferably 130mm or less. Within the above range, a better effect tends to be obtained.

[0024] For passenger car tires, H is preferably 90 mm or more, more preferably 100 mm or more, even more preferably 105 mm or more, particularly preferably 110 mm or more, and most preferably 113 mm or more. The upper limit is preferably 180 mm or less, more preferably 160 mm or less, even more preferably 140 mm or less, and particularly preferably 130 mm or less. Within the above range, a better effect tends to be obtained.

[0025] For racing tires (such as karting tires), H is preferably 55 mm or more, more preferably 57 mm or more, even more preferably 60 mm or more, and most preferably 64 mm or more. The upper limit is preferably 90 mm or less, more preferably 80 mm or less, and even more preferably 70 mm or less. Within the above range, a better effect tends to be obtained.

[0026] From the viewpoint of obtaining better performance, it is desirable that the tire's cross-sectional width Wt and cross-sectional height H satisfy the following formula. H / Wt × 100 ≥ 35% The lower limit of H / Wt × 100 is preferably 35% or more, more preferably 45% or more, even more preferably 48% or more, particularly preferably 50% or more, and most preferably 55% or more. The upper limit is preferably 70% or less, more preferably 65% ​​or less, and even more preferably 60% or less. Within the above range, a better effect tends to be obtained.

[0027] In this disclosure, A is the radial displacement of the tire at the outermost surface of the tread crown when the tire is mounted on a regular rim and then inflated to a predetermined air pressure. Specifically, it refers to the value calculated by the following formula. A = [{(Outer diameter in the radial direction of the tire at the outermost surface of the tread crown when the tire is mounted on a standard rim and the internal pressure is set to the predetermined air pressure) - (Outer diameter in the radial direction of the tire at the outermost surface of the tread crown when the tire is mounted on a standard rim and the internal pressure is set to atmospheric pressure)} / (Outer diameter in the radial direction of the tire at the outermost surface of the tread crown when the tire is mounted on a standard rim and the internal pressure is set to atmospheric pressure)] × 100 (%)

[0028] In this disclosure, the tread crown portion refers to the portion of the tire cross-section located on the tire's equatorial plane. The outermost surface of the tread crown refers to the tread surface of the tread crown (the tread surface on the tire's equator). If the tread crown has circumferential grooves, the tread surface is defined as the point where the straight line formed by connecting the outermost ends of the circumferential grooves intersects with the tire's equator.

[0029] In this disclosure, “regular rim” means the rim specified for each tire in the standards system on which the tire is based, including the standard on which the tire is based. For example, it means the standard rim for JATMA, the “Design Rim” for TRA, or the “Measuring Rim” for ETRTO. As mentioned above, the "specified air pressure" is when the virtual volume V of the tire is 15,000 cm³. 3 In the above case, the pressure is 250 kPa, and the virtual volume V of the tire is 15,000 cm³. 3If the value is less than 0.0152 × V + 22.553, the value (kPa) is calculated using the formula. The "virtual volume V of the tire" is given by V = {(Dt / 2)} 2 -(R / 2) 2 This value is calculated using the formula} × π × Wt. As mentioned above, "tire outer diameter Dt" is the outer diameter of the tire when it is mounted on a standard rim and the internal pressure is at atmospheric pressure. "Tire section width Wt" is the width obtained by subtracting the patterns, letters, etc. on the sidewalls from the straight-line distance between the sidewalls (total tire width), including all patterns and letters on the sidewall of the tire, when the tire is mounted on a regular rim and the internal pressure is at atmospheric pressure. "Tire section height H" is the length along the radial direction of the tire, from the position of the minimum outer diameter (the tip of the tire in the radial direction) to the position of the maximum outer diameter (the position on the tire's equator), when the tire is mounted on a regular rim and the internal pressure is at atmospheric pressure.

[0030] The aforementioned tire has a total thickness T (mm) at the tread crown and an outer diameter Dt (mm) of the tire that satisfies the following formula (2). (2) T / Dt ≤ 0.034 The T / Dt ratio can be set appropriately depending on the tire's application, but is preferably 0.030 or less, more preferably 0.025 or less, even more preferably 0.020 or less, and particularly preferably 0.016 or less. The lower limit is preferably 0.005 or more, more preferably 0.010 or more, and even more preferably 0.012 or more. Within the above range, better performance tends to be obtained.

[0031] For passenger car tires, T / Dt is preferably 0.030 or less, more preferably 0.025 or less, even more preferably 0.020 or less, and particularly preferably 0.016 or less. The lower limit is preferably 0.005 or more, more preferably 0.008 or more, and even more preferably 0.010 or more. When it is within the above range, the effect tends to be better obtained.

[0032] For racing tires (such as kart tires), T / Dt is preferably 0.030 or less, more preferably 0.025 or less, even more preferably 0.022 or less, and particularly preferably 0.020 or less. The lower limit is preferably 0.005 or more, more preferably 0.010 or more, and even more preferably 0.013 or more. Within the above range, better performance tends to be obtained.

[0033] From the viewpoint of obtaining better performance, it is desirable that the total thickness T (mm) of the tread crown portion of the aforementioned tire satisfies the following formula. T≦15.0mm T can be set appropriately depending on the tire's application, but is preferably 10.0 mm or less, more preferably 8.0 mm or less, even more preferably 6.0 mm or less, and particularly preferably 5.0 mm or less. The lower limit is preferably 1.0 mm or more, more preferably 2.0 mm or more, even more preferably 2.5 mm or more, and particularly preferably 3.0 mm or more. Within the above range, a better effect tends to be obtained.

[0034] For passenger car tires, T is preferably 12.0 mm or less, more preferably 11.0 mm or less, and even more preferably 10.0 mm or less. The lower limit is preferably 5.0 mm or more, more preferably 7.0 mm or more, and even more preferably 8.0 mm or more. When within the above range, a better effect tends to be obtained.

[0035] For racing tires (such as kart tires), T is preferably 8.0 mm or less, more preferably 7.0 mm or less, and even more preferably 5.0 mm or less. The lower limit is preferably 1.0 mm or more, more preferably 2.0 mm or more, and even more preferably 3.0 mm or more. Within the above range, better performance tends to be obtained.

[0036] In this disclosure, "total thickness T in the tread crown portion" refers to the distance from the tread surface to the inner surface of the tread on the equatorial plane in a cross-section cut by a plane containing the rotation axis of the tire. If the tread crown portion includes parts not made of thermoplastic elastomer composition (such as reinforcing layers or support members), it refers to the distance from the tread surface to the inner surface of the tread on the equatorial plane including those parts. Furthermore, if the tire has grooves on the equatorial plane, it refers to the straight-line distance from the intersection of the straight line connecting the outermost ends of the grooves in the radial direction of the tire and the equatorial plane. The outer diameter Dt of the tire is as described above.

[0037] The tire will be described in detail below based on an example of a preferred embodiment, with reference to the drawings as appropriate. Note that this embodiment is an example, and this disclosure is not intended to be restrictive.

[0038] Figure 1 shows a pneumatic tire 2. In Figure 1, the vertical direction is the radial direction of tire 2, the horizontal direction is the axial direction of tire 2, and the direction perpendicular to the plane of the paper is the circumferential direction of tire 2. In Figure 1, the dashed line CL represents the equatorial plane of tire 2. The shape of tire 2 is symmetrical with respect to the equatorial plane, except for the tread pattern.

[0039] This tire 2 comprises a tread section 4 and a pair of sidewall sections 6. This tire 2 is of the tubeless type. This tire 2 can be mounted on passenger cars and the like. The tire 2 may further have an elastomer layer, rubber layer, support layer, etc., that serve as a base tread and other components (clinch, bead, carcass, belt, band, inner liner, chafer, etc.).

[0040] The tread portion 4 has a shape that is convex radially outward. The tread portion 4 forms the tread surface 11 that contacts the road surface. The tread portion 4 may be a single thermoplastic elastomer composition, a laminate of multiple thermoplastic elastomer compositions, or a laminate of a vulcanized rubber composition and a thermoplastic elastomer composition. When a laminate of multiple compositions is used, it is thought that it is possible to improve the balance of performance during straight driving and cornering by laminating them in the radial direction of the tire and giving them a role such as a base tread, similar to a normal passenger car tire, or by connecting them in the width direction of the tire.

[0041] In the tire 2 shown in Figure 1, each sidewall portion 6 is joined to the end of the tread portion 4 at a joint portion 5 and extends approximately inward in the radial direction. The sidewall portion 6 may be a single thermoplastic elastomer composition, a laminate of multiple thermoplastic elastomer compositions, or a laminate of a vulcanized rubber composition and a thermoplastic elastomer composition. The sidewall portion 6 is joined to the tread portion 4 in the tire axial direction, but the tread portion 4 may be joined so as to overlap the radially outer side of the sidewall portion 6, or the sidewall portion 6 may be joined so as to overlap the radially outer side of the tread portion 4. Furthermore, the bead portion in the radially inner part of the sidewall portion 6 may be provided with a chafer or bead reinforcement layer from the viewpoint of fit with the rim and handling stability. In addition, the sidewall portion 6 may be a laminated structure consisting of multiple different compositions between the tire surface and the inner surface.

[0042] The tread portion 4 and sidewall portion 6 of tire 1 are made of a thermoplastic elastomer composition. The thermoplastic elastomer composition is a composition containing a thermoplastic elastomer.

[0043] From the viewpoint of obtaining better effects, it is desirable that the thermoplastic elastomer composition constituting the tread portion 2 has a complex modulus of elasticity Et* that satisfies the following formula. Et*≧5.0 MPa (In the formula, Et* is the complex modulus of elasticity measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.) The lower limit of Et* is preferably 6.0 MPa or higher, more preferably 6.5 MPa or higher, and even more preferably 7.0 MPa or higher. The upper limit is preferably 15.0 MPa or lower, more preferably 13.0 MPa or lower, even more preferably 11.0 MPa or lower, and particularly preferably 10.0 MPa or lower. Within the above range, the effect can be suitably obtained.

[0044] Although the mechanism by which the above effects are obtained by setting Et* within a predetermined range, particularly 5.0 MPa ≤ Et* ≤ 13.0 MPa, is not clear, it is presumed that having an Et* within a predetermined range in the tread makes it easier to reduce deformation of the tread due to internal pressure, and that good responsiveness is achieved, thereby improving handling stability.

[0045] From the viewpoint of obtaining better effects, it is desirable that the thermoplastic elastomer composition constituting the sidewall portion 3 has a complex modulus of elasticity Es* that satisfies the following formula. Es* ≥ 13.0 MPa (In the formula, Es* is the complex modulus of elasticity measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.) The lower limit of Es* is preferably 25.0 MPa or higher, more preferably 35.0 MPa or higher, even more preferably 40.0 MPa or higher, particularly preferably 42.0 MPa or higher, and most preferably 42.7 MPa or higher. The upper limit is preferably 130.0 MPa or lower, more preferably 100.0 MPa or lower, even more preferably 80.0 MPa or lower, and particularly preferably 70.0 MPa or lower. Within the above range, the effect can be suitably obtained.

[0046] Although the mechanism by which the above effects are obtained by setting Es* within a predetermined range, particularly 13.0 MPa ≤ Es* ≤ 80.0 MPa, it is presumed that having Es* within the predetermined range in the sidewall portion results in good responsiveness and improved handling stability.

[0047] From the viewpoint of obtaining better performance, it is desirable that the complex modulus of elasticity Et* (MPa) of the thermoplastic elastomer composition constituting the tread portion 2 and the complex modulus of elasticity Es* (MPa) of the thermoplastic elastomer composition constituting the sidewall portion 3 satisfy the following formula. Es* / Et*≦10.0 (In the formula, Et* is the complex modulus measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode. Es* is the complex modulus measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.) The upper limit of Es* / Et is preferably 7.0 or less, more preferably 6.1 or less, even more preferably 2.4 or less, particularly preferably 2.1 or less, and most preferably 1.9 or less. The lower limit is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 1.3 or more. Within the above range, the effect is suitably obtained.

[0048] Although the mechanism by which the above effects are obtained by setting Es* / Et* within a predetermined range is not clear, it is presumed that by making the elastic modulus of the sidewall sufficiently high compared to the elastic modulus of the tread, the sidewall does not deform excessively in response to friction generated in the tread, thereby transmitting force to the vehicle and making it easier to change the direction of the vehicle, resulting in good responsiveness and improved handling stability.

[0049] In this specification, the complex modulus E* refers to the E* of the thermoplastic elastomer composition after tire molding, and in the case of a rubber composition, it corresponds to the modulus after vulcanization. Specifically, it refers to the E* of the thermoplastic elastomer composition measured by the method described in the examples.

[0050] In this specification, E* of the thermoplastic elastomer composition is the complex modulus measured under the conditions of a temperature of 30°C, initial strain of 10%, dynamic strain of 1%, frequency of 10Hz, and extension mode. Measurement samples were taken from each component of a manufactured tire, measuring 4 mm in width, 20 mm in length, and 1 mm in thickness, with the circumferential direction of the tire and the longitudinal direction of the sample being aligned.

[0051] The E* of a thermoplastic elastomer composition can be adjusted by the type and amount of chemicals (particularly the thermoplastic elastomer, fillers, and softeners such as oils) incorporated into the composition. For example, using a polyether-based thermoplastic polyurethane elastomer tends to increase E*, while using a polyester-based thermoplastic polyurethane elastomer tends to decrease E*. Furthermore, reducing the amount of softener or increasing the amount of filler tends to increase E*.

[0052] Examples of thermoplastic elastomers used in the aforementioned thermoplastic elastomer composition include olefin-based thermoplastic elastomers, styrene-based thermoplastic elastomers (elastomer styrene-isobutylene-styrene block copolymer (SIBS), styrene-isoprene-styrene block copolymer (SIS), styrene-isobutylene block copolymer (SIB), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene-butene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-butadiene-butylene-styrene block copolymer (SBBS), etc.), PVC-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polyester-based thermoplastic elastomers, fluorine-based thermoplastic elastomers, and the like. These may be used individually or in combination of two or more. Among these, urethane-based thermoplastic elastomers (thermoplastic polyurethane elastomers (TPU)) are preferred.

[0053] Examples of thermoplastic polyurethane elastomers (urethane-based thermoplastic elastomers) include those composed of isocyanates, polyols, and, if necessary, chain extenders.

[0054] The isocyanates constituting the thermoplastic polyurethane elastomer are not particularly limited as long as they are isocyanate compounds having two or more isocyanate groups, for example, aromatic isocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 3,3'-vitrylene-4,4'-diisocyanate (TODI), xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), paraphenylenedi diisocyanate (PPDI), 4,4'-methylene-bis(phenylisocyanate); and 4,4'-dicyclohexylmethane diisocyanate (H 12 Examples include alicyclic isocyanates or aliphatic isocyanates such as MDI, hydrogenated xylylene diisocyanate (H6XDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI). These may be used individually or in combination of two or more.

[0055] Examples of polyols (high molecular weight polyols) that constitute thermoplastic polyurethane elastomers include polyether polyols such as polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), and polyoxytetramethylene glycol (PTMG); condensed polyester polyols such as polyethylene adipate (PEA), polybutylene adipate (PBA), and polyhexamethylene adipate (PHMA); lactone-based polyester polyols such as poly-ε-caprolactone (PCL); polycarbonate polyols such as polyhexamethylene carbonate; and acrylic polyols. Among these, polyether polyols and polycarbonate polyols are preferred from the viewpoint of ride comfort performance after long-term storage. These may be used individually or in combination of two or more.

[0056] Examples of chain extenders include low molecular weight polyols, polyamines, and amino alcohols. Among these, low molecular weight polyols are preferred from the viewpoint of ride comfort performance after long-term storage.

[0057] Examples of the low molecular weight polyols include triols such as glycerin, trimethylolethane, trimethylolpropane, and hexanetriol; tetraols such as pentaerythritol; and hexaols such as sorbitol. Other examples include diols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,8-octanediol, aniline diols, and bisphenol A diols. These can be used individually or in combination of two or more.

[0058] Examples of the polyamines include triamines such as diethylenetriamine and dipropylenetriamine; aliphatic diamines such as ethylenediamine and hexamethylenediamine; alicyclic diamines such as isophoronediamine and piperazine; and aromatic diamines. Aromatic diamines may be monocyclic aromatic diamines in which two amino groups are bonded to one aromatic ring, or polycyclic aromatic diamines containing two aminophenyl groups, each with at least one amino group bonded to one aromatic ring. Examples of monocyclic aromatic diamines include types in which the amino group is directly bonded to the aromatic ring, such as phenylenediamine, toluenediamine, diethyltoluenediamine, and dimethylthiotoluenediamine; and types in which the amino group is bonded to the aromatic ring via a lower alkylene group, such as xylylenediamine. Examples of polycyclic aromatic diamines include diaminodiphenylalkanes (such as 4,4'-diaminodiphenylmethane and its derivatives). These may be used individually or in combination of two or more.

[0059] Thermoplastic polyurethane elastomers can be synthesized by known methods, including the one-shot method and the prepolymer method. The one-shot method involves reacting isocyanate and polyol, etc., in a single step to achieve high molecular weight. On the other hand, the prepolymer method involves reacting isocyanate and polyol, etc., in multiple steps to achieve high molecular weight. For example, a low molecular weight urethane prepolymer is first synthesized, and then this prepolymer is reacted with the chain extender mentioned above to achieve high molecular weight.

[0060] Known catalysts can be used for the synthesis of polyurethanes. Examples of catalysts include monoamines such as triethylamine and N,N-dimethylcyclohexylamine; polyamines such as N,N,N',N'-tetramethylethylenediamine; cyclic diamines such as 1,8-diazabicyclo[5,4,0]-7-undecene (DBU) and triethylenediamine; and tin-based catalysts such as dibutyltin dilaurate and dibutyltin diacetate. These can be used individually or in combination of two or more.

[0061] The composition ratio of isocyanate to polyol in polyurethane is not particularly limited, but the NCO / OH ratio (molar ratio) of isocyanate groups to hydroxyl groups of polyol is preferably 0.5 or higher, more preferably 0.7 or higher, and even more preferably 0.8 or higher. If it falls below the lower limit, there is too little isocyanate component, which tends to reduce the mechanical strength of the urethane. On the other hand, the NCO / OH ratio (molar ratio) is preferably 2.5 or lower, more preferably 2.2 or lower, and even more preferably 2.0 or lower. If it exceeds the upper limit, there is an excess of isocyanate component, which can lead to increased moisture absorption and a decrease in the mechanical strength of the urethane.

[0062] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of thermoplastic elastomer in 100% by mass of the elastomer component is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. The upper limit is not particularly limited and may be 100% by mass. When within the above range, the effect tends to be better obtained.

[0063] The thermoplastic elastomer composition may contain other elastomer components besides the thermoplastic elastomer. Examples of other elastomer components include diene rubbers. Examples of diene rubbers include isoprene rubber, butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), and acrylonitrile-butadiene rubber (NBR). Butyl rubbers and fluororubbers are also examples. These may be used individually or in combination of two or more. From the viewpoint of suitability for tire applications, SBR, BR, and isoprene rubbers are preferred as other elastomers.

[0064] The above diene rubber may be either unmodified diene rubber or modified diene rubber. Modified diene rubbers can be any diene rubber having a functional group that interacts with a filler such as silica. Examples include end-modified diene rubbers (end-modified diene rubbers having the functional group at the end) in which at least one end of the diene rubber is modified with a compound (modifier) ​​having the functional group, main-chain modified diene rubbers having the functional group in the main chain, main-chain end-modified diene rubbers having the functional group in both the main chain and the end (for example, main-chain end-modified diene rubbers having the functional group in the main chain and at least one end modified with the modifier), and end-modified diene rubbers that are modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule, and in which hydroxyl groups or epoxy groups are introduced.

[0065] Examples of the above functional groups include amino groups, amide groups, silyl groups, alkoxysilyl groups, isocyanate groups, imino groups, imidazole groups, urea groups, ether groups, carbonyl groups, oxycarbonyl groups, mercapto groups, sulfide groups, disulfide groups, sulfonyl groups, sulfinyl groups, thiocarbonyl groups, ammonium groups, imide groups, hydrazo groups, azo groups, diazo groups, carboxyl groups, nitrile groups, pyridyl groups, alkoxy groups, hydroxyl groups, oxy groups, epoxy groups, and the like. These functional groups may have substituents. Among these, amino groups (preferably amino groups in which the hydrogen atoms of the amino group are substituted with C1-C6 alkyl groups), alkoxy groups (preferably alkoxy groups having C1-C6), and alkoxysilyl groups (preferably alkoxysilyl groups having C1-C6) are preferred.

[0066] The SBR is not particularly limited; for example, emulsion-polymerized styrene-butadiene rubber (E-SBR), solution-polymerized styrene-butadiene rubber (S-SBR), etc., can be used. These may be used individually or in combination of two or more types.

[0067] The styrene content of SBR is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, the styrene content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. The above effects are more favorably obtained when the content is within the above range. In this specification, the styrene content of SBR is as follows: 1 It is calculated by 1H-NMR measurement.

[0068] For example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Co., Ltd. can be used.

[0069] SBR can be either unmodified or modified. Modified SBR can be a type of modified SBR in which functional groups similar to those of modified diene rubber have been introduced.

[0070] When the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 contains SBR, the SBR content in 100% by mass of the elastomer component is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of ride comfort performance after long-term storage. The upper limit is preferably 90% by mass or less, more preferably 80% by mass or less.

[0071] BR is not particularly limited, and for example, high-cis BR with a high cis content, BR containing syndiotactic polybutadiene crystals, and BR synthesized using a rare-earth catalyst (rare-earth BR) can be used. These may be used individually or in combination of two or more. Among these, high-cis BR with a cis content of 90% by mass or more is preferred because it improves wear resistance.

[0072] Furthermore, BR may be either unmodified BR or modified BR. Modified BR can be a type of modified BR in which functional groups similar to those of modified diene rubber have been introduced.

[0073] When the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 contains BR, the BR content in 100% by mass of the elastomer component is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of wear resistance and the like. The upper limit is preferably 90% by mass or less, more preferably 80% by mass or less.

[0074] For example, products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Nippon Zeon Corporation can be used as BRs.

[0075] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. For NR, common types used in the rubber industry can be used, such as SIR20, RSS#3, and TSR20. For IR, there are no particular limitations; common types used in the rubber industry can be used, such as IR2200. Examples of modified NR include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Examples of modified NR include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Examples of modified IR include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These may be used individually or in combination of two or more types.

[0076] When the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 contains isoprene-based rubber, the isoprene-based rubber content in 100% by mass of the elastomer component is preferably 10% by mass or more, more preferably 20% by mass or more, from the viewpoint of low fuel consumption, etc. The upper limit is preferably 90% by mass or less, more preferably 80% by mass or less.

[0077] The thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 preferably contains a crosslinking agent from the viewpoint of obtaining a better effect. Any known crosslinking agent can be used as the crosslinking agent, but one that has the effect of partially bonding the thermoplastic elastomers together to form a network can be suitably used. In this case, for example, instead of adjusting the crosslinking state of the thermoplastic elastomer during synthesis, the crosslinking agent can be added later, kneaded in a twin-screw extruder, and heat-treated to change the crosslinking state while suppressing changes in hardness.

[0078] As such a crosslinking agent, the aforementioned isocyanates can be suitably used from the viewpoint of obtaining better effects. Among isocyanates, MDI (4,4'-diphenylmethane diisocyanate) and methylenebis(4,1-phenylene) diisocyanate are preferred, with MDI being more preferred. These may be used individually or in combination of two or more.

[0079] Furthermore, when isocyanate is used as the crosslinking agent and the thermoplastic polyurethane elastomer is used as the thermoplastic elastomer, the thermoplastic elastomer composition contains isocyanate as a crosslinking agent in addition to the isocyanate that constitutes the thermoplastic polyurethane elastomer. In other words, in this case, the thermoplastic elastomer composition contains the crosslinked thermoplastic polyurethane elastomer and isocyanate (another crosslinking agent).

[0080] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of the crosslinking agent (a crosslinking agent added separately in addition to the components of the thermoplastic elastomer) is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, even more preferably 2.5 parts by mass or more, and particularly preferably 3.0 parts by mass or more, per 100 parts by mass of the elastomer component. The upper limit is preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, even more preferably 7.0 parts by mass or less, and particularly preferably 5.0 parts by mass or less. By keeping it within the above range, good ride comfort performance after long-term storage tends to be obtained.

[0081] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of isocyanate as a crosslinking agent (isocyanate added separately in addition to the isocyanate component of the thermoplastic elastomer) is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, even more preferably 2.5 parts by mass or more, and particularly preferably 3.0 parts by mass or more, per 100 parts by mass of the elastomer component. The upper limit is preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, even more preferably 7.0 parts by mass or less, and particularly preferably 5.0 parts by mass or less. Within the above range, a better effect tends to be obtained.

[0082] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of MDI (MDI added separately in addition to the MDI components of the thermoplastic elastomer) as a crosslinking agent is preferably 1.0 part by mass or more, more preferably 2.0 parts by mass or more, even more preferably 2.5 parts by mass or more, and particularly preferably 3.0 parts by mass or more, per 100 parts by mass of the elastomer component. The upper limit is preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, even more preferably 7.0 parts by mass or less, and particularly preferably 5.0 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0083] The thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 can be appropriately blended with fillers, such as fibers. Fibrous fillers that are generally difficult to disperse in thermoplastic elastomers can also be used, and difficult-to-disperse fillers such as microfibrillated plant fibers, short fibrous cellulose, and gel-like compounds can be suitably applied.

[0084] As the above-mentioned microfibrillated plant fiber, cellulose microfibrils are preferred in that they provide good reinforcing properties. The cellulose microfibrils are not particularly limited as long as they are derived from natural products, and examples include resource biomass such as fruits, grains, and root vegetables; wood, bamboo, hemp, jute, and kenaf, as well as waste biomass such as pulp, paper, cloth, agricultural residues, food waste, and sewage sludge obtained from these raw materials, unused biomass such as rice straw, wheat straw, and thinned wood, and cellulose produced by sea squirts, acetic acid bacteria, etc. One type of these microfibrillated plant fiber may be used, or two or more types may be used in combination.

[0085] In this specification, cellulose microfibrils typically refer to cellulose fibers having an average fiber diameter of 10 μm or less, and more typically, cellulose fibers having a microstructure with an average fiber diameter of 500 nm or less, formed by an aggregate of cellulose molecules. Typical cellulose microfibrils are formed, for example, as aggregates of cellulose fibers having the average fiber diameter described above.

[0086] The method for producing the above-mentioned microfibrillated plant fibers is not particularly limited, but examples include chemically treating the raw material for the cellulose microfibrils with an alkali such as sodium hydroxide as needed, and then mechanically grinding or beating it using a refiner, twin-screw kneader (twin-screw extruder), twin-screw kneading extruder, high-pressure homogenizer, media stirring mill, millstone, grinder, vibratory mill, sand grinder, etc. In these methods, lignin is separated from the raw material by chemical treatment, so microfibrillated plant fibers that are substantially free of lignin are obtained. In addition, other methods include treating the raw material for the cellulose microfibrils under ultra-high pressure.

[0087] As the above-mentioned microfibrillated plant fibers, for example, products from Sugino Machine Co., Ltd. can be used.

[0088] Furthermore, the above-mentioned microfibrillated plant fibers may be those obtained by the above-mentioned manufacturing method, further subjected to oxidation treatment or various chemical modification treatments, or natural materials that can be the source of the above-mentioned cellulose microfibrils (for example, wood, pulp, bamboo, hemp, jute, kenaf, agricultural waste, cloth, paper, ascidian cellulose, etc.) may be used as cellulose raw materials, subjected to oxidation treatment or various chemical modification treatments, and then subjected to defibration treatment as necessary. For example, oxidized microfibrillated plant fibers can be suitably used.

[0089] Examples of oxidation treatment methods include oxidation treatment using an N-oxyl compound. This oxidation treatment using an N-oxyl compound can be carried out, for example, by using the N-oxyl compound as an oxidation catalyst in water and reacting a co-oxidant with the microfibrillated plant fibers. Examples of the N-oxyl compound include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and its derivatives. Examples of the co-oxidant include sodium hypochlorite.

[0090] The average fiber diameter of the above-mentioned microfibrillated plant fibers is preferably 10 μm or less. This range improves the dispersibility of the microfibrillated plant fibers in the elastomer. Furthermore, it tends to suppress damage to the microfibrillated plant fibers during processing. The average fiber diameter is more preferably 500 nm or less, even more preferably 100 nm or less, and particularly preferably 50 nm or less. While there is no particular lower limit to the average fiber diameter, it is preferable to have a diameter of 4 nm or more, more preferably 10 nm or more, and even more preferably 20 nm or more, because the microfibrillated plant fibers tend to become entangled and difficult to disperse.

[0091] The average fiber length of the above-mentioned microfibrillated plant fibers is preferably 100 nm or more, more preferably 300 nm or more, and even more preferably 500 nm or more. Furthermore, it is preferably 5 mm or less, more preferably 1 mm or less, even more preferably 50 μm or less, particularly preferably 3 μm or less, and most preferably 2 μm or less. When the average fiber length is below the lower limit or above the upper limit, the same tendencies as described above for the average fiber diameter are observed.

[0092] Furthermore, if the above-mentioned microfibrillated plant fibers consist of a combination of two or more types, the above-mentioned average fiber diameter and average fiber length are calculated as the average of the entire microfibrillated plant fiber.

[0093] In this specification, the average fiber diameter and average fiber length of the above-mentioned microfibrillated plant fibers can be measured by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray scattering data analysis, pore electrical resistance method (Culter principle method), etc.

[0094] Because the above-mentioned short fibrous cellulose has good dispersibility in the elastomer, it can maintain or improve the fracture strength of the elastomer without impairing it, resulting in good elastomer properties.

[0095] The fiber width of the short cellulose fibers described above is preferably 3 to 200 μm. Generally, when fibrous fillers are incorporated into thermoplastic elastomer composites, a smaller fiber width is preferable in terms of reinforcing the elastomer. However, fibrous fillers with a small fiber width tend to be difficult to orient. From the viewpoint of balancing the reinforcing properties of the elastomer and the orientation of the fibers, as well as from the viewpoint of dispersibility in the elastomer, the fiber width is preferably 10 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. Furthermore, it is preferably 120 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less.

[0096] The fiber length of the short cellulose fibers described above is preferably 20 to 1000 μm. Similar to the fiber width, from the viewpoint of balancing the reinforcing properties of the elastomer and the orientation of the fibers, and further from the viewpoint of dispersibility in the elastomer, the fiber length is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 200 μm or more. Also, it is preferably 700 μm or less, and more preferably 500 μm or less.

[0097] The above short fibrous cellulose preferably has a fiber width-to-fiber length ratio (fiber length / fiber width) of 5 to 1000. Similar to the fiber width, from the viewpoint of balancing the reinforcing properties of the elastomer and the orientation of the fibers, the fiber width-to-fiber length ratio is preferably 6 or more, more preferably 10 or more. Furthermore, it is preferably 800 or less, more preferably 500 or less, even more preferably 400 or less, and particularly preferably 300 or less.

[0098] The fiber width and fiber length of the above-mentioned short fibrous cellulose can be measured by image analysis of scanning atomic force microscopy, image analysis of scanning electron microscopy, image analysis of transmission microscopy, analysis of X-ray scattering data, pore electrical resistance method (Culter principle method), etc.

[0099] Gel compounds are substances obtained by gelling microfibrillated plant fibers or short fibrous cellulose. Even when using such gelled materials, the gel compounds can be dispersed well. The gelation method is not particularly limited and can be agitated using an ultra-high pressure homogenizer or the like.

[0100] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of the poorly dispersible filler is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of the elastomer component. The upper limit of the content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 20 parts by mass or less, and particularly preferably 10 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0101] The thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 may contain silica as a filler, from the viewpoint of various physical properties. Examples of silica include dry-process silica (anhydrous silica) and wet-process silica (hydrated silica). Among these, wet-process silica is preferred because it contains a large number of silanol groups. Commercially available products include those from Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Ltd., and Tokuyama Corporation. These may be used individually or in combination of two or more types.

[0102] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the silica content is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more, per 100 parts by mass of the elastomer component. The upper limit of the content is not particularly limited, but is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, even more preferably 170 parts by mass or less, particularly preferably 100 parts by mass or less, and most preferably 80 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0103] The nitrogen adsorption specific surface area (N2SA) of silica is preferably 70 m². 2 / g or more, more preferably 140m 2 / g or more, more preferably 160m 2 It is above / g. Setting it above the lower limit tends to result in good ride comfort performance and fracture strength after long-term storage. Furthermore, while there is no particular upper limit to the N2SA of silica, it is preferably 500m. 2 Less than / g, more preferably 300m 2 / g or less, more preferably 250m 2 It is less than / g. Keeping it below the upper limit tends to result in good variance. Note that the N2SA value of silica is measured by the BET method in accordance with ASTM D3037-93.

[0104] If the above thermoplastic elastomer composition contains silica, it is preferable that it further contains a silane coupling agent. The silane coupling agent is not particularly limited and includes, for example, bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl) trisulfide, bis(4-trimethoxysilylbutyl) trisulfide, bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, and 3-trimethoxysilylpropyl-N,N-dimethylthiocal Examples include sulfide-based compounds such as bamoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilylpropyl methacrylate monosulfide; mercapto-based compounds such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and Momentive's NXT and NXT-Z; vinyl-based compounds such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based compounds such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; glycidoxy-based compounds such as γ-glycidoxypropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane; nitro-based compounds such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chloro-based compounds such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. Commercially available products from companies such as Degussa, Momentive, Shin-Etsu Silicone Co., Ltd., Tokyo Chemical Industry Co., Ltd., Azumax Co., Ltd., and Toray Dow Corning Co., Ltd. can be used. These can be used individually or in combination of two or more types.

[0105] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of the silane coupling agent is preferably 3 parts by mass or more, and more preferably 6 parts by mass or more, per 100 parts by mass of silica. When it is 3 parts by mass or more, good fracture strength and the like tend to be obtained. Furthermore, the above content is preferably 20 parts by mass or less, and more preferably 15 parts by mass or less. When it is 20 parts by mass or less, the effect commensurate with the amount added tends to be obtained.

[0106] The thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 may contain carbon black as a filler, from the viewpoint of various physical properties. It is believed that using carbon black can easily improve the strength of the elastomer composition.

[0107] While not particularly limited, examples of carbon black include N134, N110, N220, N234, N219, N339, N330, N326, N351, N550, and N762. Commercially available products include those from Asahi Carbon Co., Ltd., Cabot Japan Co., Ltd., Tokai Carbon Co., Ltd., Mitsubishi Chemical Corporation, Lion Corporation, Shin-Nippon Chemical Carbon Co., Ltd., and Columbia Carbon Corporation. These can be used individually or in combination of two or more types.

[0108] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the carbon black content is preferably 1 part by mass or more, more preferably 3 parts by mass or more, per 100 parts by mass of the elastomer component. Furthermore, the above content is preferably 20 parts by mass or less, more preferably 15 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0109] The specific surface area (N2SA) of carbon black for nitrogen adsorption is 50 m². 2 Preferably 80m / g or more. 2 More preferably 100m / g or more, 2 More preferably, the amount of N2SA is 200m 2 Preferably less than / g, 150m2 More preferably less than / g, 130m 2 A value of less than / g is even more preferable. Within the above range, there is a tendency to obtain better effects. The specific surface area for nitrogen adsorption of carbon black is determined according to JIS K6217-2:2001.

[0110] The above thermoplastic elastomer composition may contain other fillers besides the flame-retardant filler, silica, and carbon black. Examples of other fillers include calcium carbonate, talc, alumina, clay, aluminum hydroxide, aluminum oxide, and mica.

[0111] The thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 may contain a plasticizer. The plasticizer is not particularly limited, but examples include liquid plasticizers that are liquid at 25°C, such as oil and liquid resin, and solid plasticizers that are solid at 25°C, such as resins (polymers that are solid at room temperature (25°C)). One type of plasticizer may be used, or two or more types may be used in combination.

[0112] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of plasticizers (total amount of liquid plasticizers, solid plasticizers, etc.) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the elastomer component. Furthermore, the above content is preferably 80 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 50 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0113] The above oils are not particularly limited, and conventionally known oils can be used, such as paraffinic process oils, aromatic process oils, naphthenic process oils, low PCA (polycyclic aromatic) process oils such as TDAE and MES, vegetable oils, and mixtures thereof. Among these, aromatic process oils are preferred in terms of wear resistance and fracture characteristics. Specific examples of aromatic process oils include the Diana Process Oil AH series manufactured by Idemitsu Kosan Co., Ltd.

[0114] The above-mentioned liquid resin is not particularly limited, but examples include liquid aromatic vinyl polymers, coumarone indene resins, indene resins, terpene resins, rosin resins, or hydrogenated versions thereof.

[0115] Liquid aromatic vinyl polymers are resins obtained by polymerizing α-methylstyrene and / or styrene, and include liquid resins such as styrene homopolymers, α-methylstyrene homopolymers, and copolymers of α-methylstyrene and styrene.

[0116] Liquid coumarone-indene resin is a resin that contains coumarone and indene as the main monomer components that make up the resin's backbone (main chain). Other monomer components that may be included in the backbone besides coumarone and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0117] Liquid indene resin is a liquid resin that contains indene as the main monomer component that makes up the resin's backbone (main chain).

[0118] Liquid terpene resins are resins obtained by polymerizing terpene compounds such as α-pinene, β-pinene, camphene, and dipetene, or liquid terpene-based resins such as terpenephenols, which are obtained using terpene compounds and phenolic compounds as raw materials.

[0119] Liquid rosin resins are liquid rosin-based resins represented by natural rosin, polymerized rosin, modified rosin, their ester compounds, or hydrogenated versions thereof.

[0120] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of the liquid plasticizer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the elastomer component. Furthermore, the above content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0121] The solid resin is not particularly limited, but examples include solid styrene resins, coumarone indene resins, terpene resins, pt-butylphenol acetylene resins, acrylic resins, dicyclopentadiene resins (DCPD resins), C5 petroleum resins, C9 petroleum resins, and C5C9 petroleum resins. These may be used individually or in combination of two or more.

[0122] Solid styrene resins are solid polymers that use styrene monomers as constituent monomers, and include polymers polymerized with styrene monomers as the main component (50% by mass or more). Specifically, examples include homopolymers obtained by polymerizing styrene monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) individually, copolymers obtained by copolymerizing two or more styrene monomers, and copolymers of styrene monomers and other monomers that can copolymerize with them.

[0123] Examples of other monomers mentioned above include acrylonitriles such as acrylonitrile and methacrylonitrile, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, unsaturated carboxylic acid esters such as methyl acrylate and methyl methacrylate, dienes such as chloroprene and butadiene isoprene, olefins such as 1-butene and 1-pentene; α,β-unsaturated carboxylic acids such as maleic anhydride or their acid anhydrides; and so on.

[0124] Among these, solid α-methylstyrene resins (α-methylstyrene homopolymers, copolymers of α-methylstyrene and styrene, etc.) are preferred.

[0125] Examples of solid coumarone indene resins include solid resins having the same constituent units as the liquid coumarone indene resin described above.

[0126] Examples of solid terpene resins include polyterpenes, terpene phenols, and aromatically modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrogenated products. Terpene compounds are (C5H8) n A hydrocarbon and its oxygen-containing derivative represented by the following composition, monoterpene (C 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpene (C 20 H 32 These are compounds with a terpene as their basic skeleton, classified as such, and examples include α-pinene, β-pinene, dipentene, limonene, myrcene, allocimene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, and γ-terpineol.

[0127] Examples of solid polyterpenes include terpene resins such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin, which are made from the terpene compounds mentioned above, as well as solid resins such as hydrogenated terpene resins, which are obtained by hydrogenating the terpene resins.

[0128] Examples of solid terpene phenols include solid resins obtained by copolymerizing the above-mentioned terpene compound with a phenolic compound, and solid resins obtained by hydrogenating the resin. Specifically, examples include solid resins obtained by condensing the above-mentioned terpene compound, a phenolic compound, and formalin. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol.

[0129] Examples of solid aromatically modified terpene resins include solid resins obtained by modifying terpene resins with aromatic compounds, and solid resins obtained by hydrogenating the resins. The aromatic compounds are not particularly limited as long as they are compounds having an aromatic ring, but examples include phenol compounds such as phenol, alkylphenol, alkoxyphenol, and phenol containing an unsaturated hydrocarbon group; naphthol compounds such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthol containing an unsaturated hydrocarbon group; styrene derivatives such as styrene, alkylstyrene, alkoxystyrene, and styrene containing an unsaturated hydrocarbon group; coumarone, indene, and the like.

[0130] Examples of solid pt-butylphenol acetylene resins include solid resins obtained by a condensation reaction between pt-butylphenol and acetylene.

[0131] While there are no particular limitations on the solid acrylic resin, solvent-free acrylic solid resins are preferably used because they have fewer impurities and a sharper molecular weight distribution.

[0132] Examples of solid, solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized by high-temperature continuous polymerization (high-temperature continuous bulk polymerization) (as described in U.S. Patent No. 4,414,370, Japanese Patent Publication No. 59-6207, Japanese Patent Publication No. 5-58005, Japanese Patent Publication No. 1-313522, U.S. Patent No. 5,010,166, and the Toa Gosei Research Annual Report TREND2000 No. 3, pp. 42-45, etc.) with minimal use of polymerization initiators, chain transfer agents, organic solvents, and other auxiliary raw materials. In this specification, (meth)acrylic means methacrylic and acrylic.

[0133] The solid acrylic resin preferably does not contain substantially any secondary raw materials such as polymerization initiators, chain transfer agents, or organic solvents. Furthermore, the acrylic resin obtained by continuous polymerization preferably has a relatively narrow compositional distribution and molecular weight distribution.

[0134] As described above, the solid acrylic resin is preferably one that does not contain polymerization initiators, chain transfer agents, organic solvents, etc., which are substantially auxiliary raw materials, i.e., one with high purity. The purity of the solid acrylic resin (the proportion of resin contained in the resin) is preferably 95% by mass or more, more preferably 97% by mass or more.

[0135] Examples of monomer components that constitute solid acrylic resins include (meth)acrylic acid, (meth)acrylic acid esters (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylic acid derivatives such as (meth)acrylamide derivatives.

[0136] Furthermore, as monomer components constituting the solid acrylic resin, aromatic vinyls such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, and divinylnaphthalene may be used along with (meth)acrylic acid and (meth)acrylic acid derivatives.

[0137] The solid acrylic resin may be a resin composed solely of (meth)acrylic components, or a resin that also contains components other than (meth)acrylic components. Furthermore, the solid acrylic resin may have hydroxyl groups, carboxyl groups, silanol groups, etc.

[0138] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of the solid plasticizer is preferably 1 part by mass or more, more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more, per 100 parts by mass of the elastomer component. Furthermore, the above content is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. When the content is within the above range, a better effect tends to be obtained.

[0139] Examples of liquid and solid plasticizers that can be used include products from Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Corporation, Rutgers Chemicals, BASF, Arizona Chemical Company, Nippon Paint Chemical Co., Ltd., Nippon Shokubai Co., Ltd., JXTG Energy Corporation, Arakawa Chemical Industries, Ltd., and Taoka Chemical Industries, Ltd.

[0140] The thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6 preferably contains an anti-aging agent from the viewpoint of crack resistance, ozone resistance, etc.

[0141] While not particularly limited, the following are examples of anti-aging agents: naphthylamine-based anti-aging agents such as phenyl-α-naphthylamine; diphenylamine-based anti-aging agents such as octylated diphenylamine and 4,4′-bis(α,α′-dimethylbenzyl)diphenylamine; N-isopropyl-N′-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine, and N,N′-di-2-naphthyl-p-phenylenediamine. Examples of anti-aging agents include p-phenylenediamine-based anti-aging agents such as amines; quinoline-based anti-aging agents such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based anti-aging agents such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; and bis, tris, and polyphenol-based anti-aging agents such as tetrakis-[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane. Among these, p-phenylenediamine-based anti-aging agents and quinoline-based anti-aging agents are preferred, and polymers of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine and 2,2,4-trimethyl-1,2-dihydroquinoline are more preferred. Commercial products such as those from Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinko Chemical Co., Ltd., and Flexis Co., Ltd. can be used.

[0142] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the content of the anti-aging agent is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, per 100 parts by mass of the elastomer component. A content above the lower limit tends to provide sufficient ozone resistance. The content is preferably 7.0 parts by mass or less, more preferably 4.0 parts by mass or less. A content below the upper limit tends to provide a good appearance.

[0143] The above thermoplastic elastomer composition may contain stearic acid. In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the stearic acid content is preferably 0.5 to 10 parts by mass or more, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the elastomer component.

[0144] In addition, conventionally known stearic acid can be used, such as products from NOF Corporation, NOF Corporation, Kao Corporation, Fujifilm Wako Pure Chemical Corporation, Chiba Fatty Acid Co., Ltd.

[0145] The thermoplastic elastomer composition described above preferably contains zinc oxide. In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the zinc oxide content is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the elastomer component.

[0146] In addition, conventionally known zinc oxides can be used, such as products from Mitsui Mining & Smelting Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0147] The above thermoplastic elastomer composition may contain wax. The wax is not particularly limited and includes petroleum-based waxes, natural waxes, and synthetic waxes obtained by refining or chemically treating multiple waxes. These waxes may be used individually or in combination of two or more types.

[0148] Examples of petroleum-based waxes include paraffin wax and microcrystalline wax. Examples of natural waxes are not limited to those derived from non-petroleum resources, and include plant-based waxes such as candelilla wax, carnauba wax, wood wax, rice wax, and jojoba wax; animal-based waxes such as beeswax, lanolin, and whale wax; mineral waxes such as ozokerite, ceresin, and petrolactam; and refined products thereof. Commercially available products include those from companies such as Ouchi Shinko Chemical Industry Co., Ltd., Nippon Seiro Co., Ltd., and Seiko Chemical Co., Ltd. The wax content should be set appropriately in terms of ozone resistance and cost.

[0149] If the thermoplastic elastomer composition contains a diene-based rubber component, sulfur may be added to form appropriate cross-linked chains in the polymer chains of the diene-based rubber component, thereby providing a good balance of performance.

[0150] In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, the sulfur content is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more, per 100 parts by mass of the diene-based rubber component. The content is preferably 6.0 parts by mass or less, more preferably 4.0 parts by mass or less, and even more preferably 3.0 parts by mass or less.

[0151] Examples of sulfur commonly used in the rubber industry include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersible sulfur, and soluble sulfur. Commercially available products include those from Tsurumi Chemical Industries, Karuizawa Sulfur Co., Ltd., Shikoku Chemicals Co., Ltd., Flexis Co., Ltd., Nippon Dry Distillation Co., Ltd., and Hosoi Chemical Industry Co., Ltd. These can be used individually or in combination of two or more types.

[0152] The above thermoplastic elastomer composition may contain a vulcanization accelerator. In the thermoplastic elastomer composition constituting the tread portion 4 and the sidewall portion 6, there are no particular restrictions on the content of the vulcanization accelerator, and it can be freely determined according to the desired vulcanization rate and crosslinking density. However, it is usually 0.3 to 10 parts by mass, preferably 0.5 to 7 parts by mass, per 100 parts by mass of the elastomer component.

[0153] There are no particular restrictions on the type of vulcanization accelerator; commonly used ones can be used. Examples of vulcanization accelerators include thiazole-based vulcanization accelerators such as 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, and N-cyclohexyl-2-benzothiadylsulfenamide; thiuram-based vulcanization accelerators such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetrakis(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators such as N-cyclohexyl-2-benzothiazolesulfenamide, Nt-butyl-2-benzothiazolylsulfenamide, N-oxyethylene-2-benzothiazolesulfenamide, and N,N'-diisopropyl-2-benzothiazolesulfenamide; and guanidine-based vulcanization accelerators such as diphenylguanidine, diortotrilguanidine, and orthotrilbiguanidine. These may be used individually or in combination of two or more. Among them, sulfenamide-based vulcanization accelerators and guanidine-based vulcanization accelerators are preferred from the viewpoint of the aforementioned performance balance.

[0154] In addition to the above-mentioned components, the thermoplastic elastomer composition may also contain, as appropriate, conventional additives used in the application field, such as mold release agents and pigments.

[0155] As for the method of producing the above thermoplastic elastomer composition, known methods can be used. For example, it can be produced using known molding methods such as injection molding with the above thermoplastic elastomer and other components. Alternatively, it can be produced by kneading the above components using a rubber kneading device such as an open roll or Banbury mixer, and crosslinking as necessary. The kneading conditions are that the kneading temperature is usually 50 to 200°C, preferably 80 to 190°C, and the kneading time is usually 30 seconds to 30 minutes, preferably 1 minute to 30 minutes.

[0156] In particular, the thermoplastic elastomer composition is preferably prepared by heat-treating a composition containing the thermoplastic elastomer, etc., under conditions of 100°C or higher, and especially preferably prepared by heat-treating a composition containing the thermoplastic polyurethane elastomer and 4,4'-diphenylmethane diisocyanate under conditions of 100°C or higher. The heat treatment temperature is more preferably 130°C or higher, even more preferably 140°C or higher, and particularly preferably 150°C or higher. The heat treatment time is not particularly limited and may be set as appropriate, but is preferably 0.5 to 24 hours, more preferably 2 to 12 hours, and even more preferably 3 to 8 hours.

[0157] In tire 2, each sidewall portion 6 is joined to the end of the tread portion 4. From the viewpoint of obtaining a better effect, it is desirable that the joining portion 6 be located outward in the tire width direction from a distance of 1 / 4 of the tire's cross-sectional width Wt (Wt / 4) from the tire's equatorial plane. Although the mechanism by which these effects are achieved is not clear, it is presumed that the entire thermoplastic elastomer composition constituting the tread becomes more easily in contact with the ground, further improving handling stability.

[0158] The tread portion 4, the sidewall portion 6, and other components as needed can be joined using known methods for joining thermoplastic elastomer compositions. Examples include hot plate welding, adhesive welding, vibration welding, ultrasonic welding, injection welding, and laser welding.

[0159] As shown in Figure 1, from the viewpoint of obtaining a better effect, it is desirable that the tread portion 4 is provided with a tread portion reinforcing layer 4a within the tread portion 4. Although the mechanism by which these effects are achieved is not clear, it is presumed that the inclusion of a reinforcing layer within the tread suppresses deformation under high internal pressure and during rolling, thereby further improving handling stability.

[0160] The tread reinforcement layer 4a can be applied without particular limitations, as long as it is a member that has the function of reinforcing the tread portion 4. In Figure 1, the tire 2 has the tread reinforcement layer 4a positioned slightly inward in the tire radial direction within the tread. However, it can be placed at any position within the tread 4, and the appropriate position should be selected considering the reinforcement effect. Examples include near the center of the tire radial direction within the tread, outward, inward, and on the innermost surface of the tread.

[0161] From the viewpoint of obtaining a better effect, it is desirable that the tire 2 is provided with a support member 8 on at least a portion of the tread portion 4 and / or sidewall portion 6 on the inner side of the tire cavity. Although the mechanism by which such effects are achieved is not clear, it is presumed that by providing support members on the inner surface side of the tire in the tread and sidewall sections, the entire tire is supported, deformation is suppressed, and handling stability is further improved.

[0162] In the tire 2 shown in Figure 1, support members 8 are provided on the entire inner surface of the tread portion 4 and the sidewall portion 6. However, support members 8 may be provided only on the inner surface of the tread portion 4 or only on the inner surface of the sidewall portion 6. Alternatively, support members 8 may be provided on only a portion of the inner surface of the tread portion 4 and the sidewall portion 6. In particular, from the viewpoint of obtaining a better effect, it is desirable that support members 8 be provided on the entire inner surface of the tread portion 4 and the sidewall portion 6. Furthermore, other layers or members may be provided between the tread portion 4 and the support member 8, or between the sidewall portion 6 and the support member 8.

[0163] From the viewpoint of obtaining better effects, it is desirable that the tread reinforcement layer 4a and the support member 8 be layers and members made of various resins.

[0164] Any resin capable of providing the above-mentioned effects can be used as the resin for the tread reinforcement layer 4a and the support member 8. Specifically, these include polyethylene resins (low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, etc.), polyolefin resins such as polypropylene resins; cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), poly(meth)acrylic resins, polycarbonate resins, polyvinyl alcohol resins, ethylene-vinyl ester copolymer saponifies, polyethylene terephthalate, polyethylene naphthalate, and other polyester resins; various types of nylon and other polyamide resins; polyurethane resins; acetal resins; cellulose resins; and others.

[0165] In particular, from the viewpoint of obtaining better effects, polyolefin resins and polyester resins are preferred for the tread reinforcement layer 4a, and polyethylene resins and polypropylene resins are more preferred. Furthermore, polyester resins and polyurethane resins are preferred for the support member 8, and polyethylene terephthalate is more preferred.

[0166] Furthermore, metal fiber cords such as steel, or organic fiber cords such as polyester, nylon, rayon, and aramid can also be suitably used for the tread reinforcement layer 4a and the support member 8.

[0167] From the viewpoint of obtaining a better effect, the tensile modulus of the support member 8 is preferably 0.05 GPa or higher, more preferably 0.1 GPa or higher, even more preferably 0.5 GPa or higher, and particularly preferably 0.9 GPa or higher. The upper limit is preferably 13.0 GPa or lower, more preferably 3.0 GPa or lower, even more preferably 2.0 GPa or lower, and particularly preferably 1.5 GPa or lower. In this disclosure, the tensile modulus is a value measured in accordance with JIS R7606.

[0168] Although the mechanism by which the above effects are obtained by setting the tensile modulus within a predetermined range, particularly 0.1 to 13.0 GPa, is not clear, it is presumed that the support member having a tensile modulus within a predetermined range results in good responsiveness and improved handling stability.

[0169] The thickness of the tread reinforcement layer 4a is preferably 0.5 mm or more, more preferably 0.7 mm or more, even more preferably 0.8 mm or more, particularly preferably 1.0 mm or more, and also preferably 2.5 mm or less, more preferably 2.0 mm or less, and even more preferably 1.5 mm or less. When the thickness is within the above range, a better effect tends to be obtained. In this disclosure, "thickness of the tread reinforcement layer" is the average value of the thickness of the tread reinforcement layer at each point on the surface of the tread reinforcement layer in a cross-section cut by a plane containing the rotation axis of the tire. In the tire shown in Figure 2, T4a indicates the thickness at one point on the surface of the tread reinforcement layer, and the thickness of the tread reinforcement layer 4a represents the average value at each point.

[0170] The cross-sectional width of the tread reinforcement layer 4a in the tire width direction is preferably 50 mm or more, more preferably 65 mm or more, even more preferably 70 mm or more, and also preferably 300 mm or less, more preferably 270 mm or less, and even more preferably 250 mm or less. When it is within the above range, the effect tends to be better obtained. In this disclosure, "cross-sectional width in the tire width direction of the tread reinforcement layer" refers to the straight-line distance between the two ends of the tread reinforcement layer in the tire width direction in a cross-section cut by a plane containing the tire's axis of rotation, and in tire 2 of Figure 1, this refers to W4a.

[0171] The cross-sectional width (mm) in the tire circumferential direction of the tread reinforcement layer 4a and the thickness (mm) of the tread reinforcement layer 4a are preferably 50 or more, more preferably 65 or more, even more preferably 70 or more, and also preferably 300 or less, more preferably 270 or less, and even more preferably 250 or less. Within the above range, a better effect tends to be obtained.

[0172] The thickness of the support member 8 is preferably 0.5 mm or more, more preferably 0.7 mm or more, even more preferably 0.8 mm or more, particularly preferably 1.0 mm or more, and also preferably 2.0 mm or less, more preferably 1.8 mm or less, and even more preferably 1.5 mm or less. When the thickness is within the above range, a better effect tends to be obtained. In this disclosure, "thickness of the support member" refers to the average value of the thickness of the support member at each point on the surface of the support member in a cross-section cut by a plane containing the rotation axis of the tire. In the tire shown in Figure 2, T8 indicates the thickness at one point on the surface of the support member, and the thickness of the support member 8 represents the average value at each point.

[0173] Tire 2 may have a composition layer in the bead area that performs a similar role to conventional rubber compositions such as clinch or bead apex, from the viewpoint of handling stability, or it may have a core made of a non-stretchable wire wound with steel cord.

[0174] Furthermore, the tire 2 may have a carcass in the tread and sidewall portions, similar to conventional tires. The carcass consists of carcass plies, each carcass ply consisting of a number of parallel cords and a covering layer. The absolute value of the angle that each cord makes with respect to the tire's equatorial plane is preferably between 75° and 90°. In other words, it is preferable that the carcass has a radial structure. The cords are made of organic fibers. Examples of preferred organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0175] Furthermore, tire 2 may have a belt layer and a belt reinforcement layer in the tread area. Although not shown in the figures, the belt layer and the belt reinforcement layer may each include a number of parallel cords and a covering layer. When a belt layer is provided, each cord is preferably inclined with respect to the equatorial plane, and the general absolute value of the inclination angle is 10° to 35°. When there are multiple belt layers, it is preferable that the inclination directions of two adjacent layers with respect to the tire equatorial plane are opposite. The preferred material for the cords of the belt layer is steel. Organic fibers may be used for the cords. In this case, examples of organic fibers include polyester fibers, nylon fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0176] If a belt reinforcement layer is provided, it is preferable that it be provided on the radially outer side of the belt layer. Although not shown, the belt reinforcement layer includes a cord and a covering layer. The cord is wound spirally and may have a so-called jointless structure. The cord extends substantially in the circumferential direction, and the angle of the cord with respect to the circumferential direction is 5° or less, and even 2° or less. The belt layer is restrained by this cord, so that lifting of the belt layer is suppressed. The cord is made of organic fibers. Examples of preferred organic fibers include nylon fibers, polyester fibers, rayon fibers, polyethylene naphthalate fibers, and aramid fibers.

[0177] By incorporating any of the above-mentioned carcass, belt layer, or belt reinforcement layer, it is possible to reduce the deformation applied to the tire, thereby reducing permanent deformation during tire storage and making it easier to improve ride comfort after storage.

[0178] Furthermore, the innermost layer of the tire may be provided with an elastomer layer that has excellent resistance to air permeability. This elastomer layer may be a so-called inner liner containing butyl rubber, or a thermoplastic elastomer layer using styrene-isobutylene-styrene copolymer, etc. It is believed that providing such a layer makes it easier to maintain air pressure, prevents the tire from deforming due to the weight of the vehicle during storage, and helps maintain ride comfort performance after long-term storage.

[0179] Figure 2 shows a cross-section of the tread portion 4 of the tire 2, cut along a plane containing the tire axis. In Figures 1 and 2, the crown center 17, which is the position of the equatorial plane CL, corresponds to the "tread crown portion." After the tire 2 is mounted on the regular rim and filled with a predetermined air pressure, the radial displacement A of the outermost surface 14 of the tread crown portion satisfies equation (1).

[0180] In tire 2, the total thickness T of the tread portion 4 on the equatorial plane of the tire's radial cross-section (total thickness at the tread crown portion) is the distance from the tread surface 11 on the equatorial plane (since tire 1 has grooves on the tire's equatorial plane, this is a straight line connecting the ends of the grooves 7 on the outermost radial surface of the tire) to the inner surface 12 of the tread, in a cross-section cut by a plane containing the tire's axis. The total thickness T (mm) at the tread crown portion and the outer diameter Dt (mm) of the tire satisfy equation (2) above. [Examples]

[0181] The following examples (implementations) are considered preferable for implementation, but the scope of this disclosure is not limited to these examples.

[0182] The following tables show the results of examining compositions obtained by varying the formulations of various chemicals according to the tables below, and the tires made from these compositions, based on the evaluation method described below. TPU1: BASF Elastolane 1198ATR (polyether-based thermoplastic polyurethane elastomer) TPU2: BASF Elastolane 1180A (polyether-based thermoplastic polyurethane elastomer) TPU3: BASF Elastolane C60A10WN (Polyester-based thermoplastic polyurethane elastomer) TPU4: Lezamin P-2283 (thermoplastic polyurethane elastomer) manufactured by Dainichi Seika Kogyo Co., Ltd. TPU5: Lezamin P-6165 (thermoplastic polyurethane elastomer) manufactured by Dainichi Seika Kogyo Co., Ltd. TPU6: Lezamin PB-2285 (thermoplastic polyurethane elastomer) manufactured by Dainichi Seika Kogyo Co., Ltd. TPU7: Lezamin P-2275 (thermoplastic polyurethane elastomer) manufactured by Dainichi Seika Kogyo Co., Ltd. Crosslinking agent: 4,4'-diphenylmethane diisocyanate (MDI), manufactured by Dainichi Seika Kogyo Co., Ltd. (MDI content 30-40%), the amount of crosslinking agent listed in Table 1 is the amount as MDI. LDPE: Novatec LD LJ902, manufactured by Japan Polyethylene Co., Ltd. HDPE: Made by Japan Polyethylene Novatec HD HJ360 PET: Unitika SA-1206

[0183] (Preparation of thermoplastic elastomer compositions) According to the formulations in Table 1, the mixture was kneaded in a twin-screw extruder to produce a thermoplastic elastomer composition (without heat treatment). Then, the obtained thermoplastic elastomer composition (without heat treatment) was heat-treated in a dryer at 100°C for 6 hours to obtain thermoplastic elastomer compositions (with heat treatment) of formulations A to H.

[0184] [Table 1]

[0185] (Preparation of test tires) The thermoplastic elastomer compositions (with heat treatment) of formulations A to H in Table 1 are injection molded into the tread and sidewall shapes according to the specifications in Tables 2 and 3. In tread injection molding, specifications that include a tread reinforcement layer include the tread reinforcement layer inside, forming the entire tread portion of the tire (in Tables 2 and 3, a "-" in the tread reinforcement layer column indicates no tread reinforcement layer, while the listed thickness and cross-sectional width in the tire width direction indicate those thickness and cross-sectional width). In injection molding of the sidewall, the bead wire is housed internally to improve fit with the rim, forming the entire sidewall of the tire. Furthermore, the support members are injection molded to the shape specified in Tables 2 and 3 (a "-" in the support member column indicates no support member, while a material name is listed, indicating an internal support layer made of that material). By welding each injection-molded part afterward, the test tire shown in Figure 1 (specifications: Tables 2 and 3, Table 2: kart tire, Table 3: passenger car tire (205 / 55R16)) is obtained.

[0186] Tables 1, 2, and 3 show the results calculated based on the evaluation method below, assuming test tires obtained according to the specifications for thermoplastic elastomer compositions A to H (with heat treatment) obtained by varying the formulation according to Table 1, and for test tires obtained according to the specifications. The reference comparative examples are as follows. Table 2: Comparative Examples 1-9 Table 3: Comparative Example 2-9

[0187] <Viscoelasticity Test> Samples of each of the thermoplastic elastomer compositions (with heat treatment) of formulations A to H were taken from the tread and sidewall of the test tire, with dimensions of 4 mm in width, 20 mm in length, and 1 mm in thickness. The complex modulus of each sample was measured using an RSA series instrument manufactured by TA Instruments under the conditions of a temperature of 30°C, initial strain of 10%, dynamic strain of 1%, frequency of 10 Hz, and extension mode.

[0188] <Tensile modulus> The tensile modulus of the support member is measured in accordance with JIS R7606.

[0189] <Handling Stability> The test tire is mounted on a rim, and with internal pressure applied, the handling stability is calculated by simulation when it is rolled under a load simulating that of a 1500cc passenger car. The results are displayed as a score with the standard comparison example set to 100, and a higher number indicates superior handling stability.

[0190] [Table 2]

[0191] [Table 3]

[0192] (1) The present disclosure relates to a tire in which the tread portion and sidewall portion are formed from a thermoplastic elastomer composition, After mounting the tire onto a standard rim and filling it with the following specified air pressure, the radial displacement A at the outermost surface of the tread crown satisfies the following equation (1): (1) A ≤ 3.0% The tire is one in which the total thickness T (mm) at the tread crown and the outer diameter Dt (mm) of the tire satisfy the following formula (2). (2) T / Dt ≤ 0.034 <Specified air pressure> The virtual volume V of the tire is 15,000 cm³ 3 In the above cases: 250 (kPa) The virtual volume V of the tire is 15,000 cm³ 3 If less than: 0.0152 × V + 22.553 (kPa) Note that the virtual volume V (mm²) of the tire 3 The tire diameter is calculated using the following formula, with the tire's outer diameter Dt (mm), tire's section width Wt (mm), rim diameter R (mm), and tire's section height H (mm). V = {(Dt / 2)} 2 -(R / 2) 2} × π × Wt R = Dt - 2H (In the formula, Dt, Wt, and H are all values ​​obtained when the tire is mounted on a standard rim and the internal pressure is at atmospheric pressure.)

[0193] Disclosure (2) is the tire according to Disclosure (1), wherein the joint between the tread portion and the sidewall portion is located outside the tire width direction by more than Wt / 4 (mm) from the tire equatorial plane.

[0194] Disclosure (3) is the tire according to Disclosure (1) or (2) having a tread reinforcing layer within the tread portion.

[0195] Disclosure (4) is a tire according to any one of Disclosures (1) to (3) wherein a support member is provided on the inner side of the tire of the tread portion and / or on the inner side of the tire of the sidewall portion.

[0196] This disclosure (5) is the tire described in this disclosure (4), wherein the tensile modulus of the support member is 0.1 to 13.0 GPa.

[0197] Disclosure (6) is a tire according to any of Disclosures (1) to (5) in which the thermoplastic elastomer composition constituting the tread portion has a complex modulus of elasticity Et* that satisfies the following formula. 5.0 MPa ≤ Et* ≤ 13.0 MPa (In the formula, Et* is the complex modulus of elasticity measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.)

[0198] Disclosure (7) relates to a tire according to any of Disclosures (1) to (6) wherein the thermoplastic elastomer composition constituting the sidewall portion has a complex modulus of elasticity Es* that satisfies the following formula. 13.0 MPa ≤ Es* ≤ 80.0 MPa (In the formula, Es* is the complex modulus of elasticity measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.)

[0199] Disclosure (8) is a tire according to any of Disclosures (1) to (7) wherein the tire section width Wt (mm) and tire section height H (mm) satisfy the following formula. H / Wt × 100 ≥ 45%

[0200] Disclosure (9) is a tire according to any of Disclosures (1) to (8) in which the complex modulus of elasticity Et* (MPa) of the thermoplastic elastomer composition constituting the tread portion and the complex modulus of elasticity Es* (MPa) of the thermoplastic elastomer composition constituting the sidewall portion satisfy the following formula. Es* / Et*≦7.0 (In the formula, Et* is the complex modulus measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode. Es* is the complex modulus measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.) [Explanation of Symbols]

[0201] 2. Pneumatic tires 4 Tread section 5 Joint 6. Sidewall section 4a Tread reinforcement layer 8. Support Member 11 Tread surface 12 Tread inner surface 14. Outer surface of the tread crown. 17. Tread crown area (crown center) CL Tire 2 equatorial plane T Total thickness of the tread crown Thickness of a single point on the surface of the T4a tread reinforcement layer W4a Tread reinforcement layer cross-sectional width in the tire width direction T8 Thickness at one point on the surface of the support member

Claims

1. A tire in which the tread portion and sidewall portion are formed from a thermoplastic elastomer composition, After mounting the tire onto a standard rim and filling it with the following specified air pressure, the radial displacement A at the outermost surface of the tread crown satisfies the following equation (1): (1) A ≤ 3.0% The total thickness T (mm) at the tread crown and the outer diameter Dt (mm) of the tire satisfy the following equation (2): (2) T / Dt≦0.034 The thermoplastic elastomer composition constituting the tread portion of the tire satisfies the following formula for its complex modulus of elasticity Et*. 5.0MPa≦Et*≦13.0MPa (In the formula, Et* is the complex modulus of elasticity measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.) <Specified air pressure> The virtual volume V of the tire is 15,000 cm³. ３ In the above case: 250 (kPa) The virtual volume V of the tire is 15,000 cm³. ３ If less than: 0.0152 × V + 22.553 (kPa) Note that the virtual volume V (mm) of the tire ３ The tire diameter is calculated using the following formula, with the tire's outer diameter Dt (mm), tire's section width Wt (mm), rim diameter R (mm), and tire's section height H (mm). V={(Dt / 2) ２ -(R / 2) ２ }×π×Wt R = Dt - 2H (In the formula, Dt, Wt, and H are all values ​​obtained when the tire is mounted on a standard rim and the internal pressure is at atmospheric pressure.)

2. A tire in which the tread portion and the sidewall portion are formed from a thermoplastic elastomer composition, After mounting the tire onto a standard rim and filling it with the following specified air pressure, the radial displacement A at the outermost surface of the tread crown satisfies the following equation (1): (1) A ≤ 3.0% The total thickness T (mm) at the tread crown and the outer diameter Dt (mm) of the tire satisfy the following equation (2): (2) T / Dt≦0.034 A tire in which the complex modulus of elasticity Et* (MPa) of the thermoplastic elastomer composition constituting the tread and the complex modulus of elasticity Es* (MPa) of the thermoplastic elastomer composition constituting the sidewall satisfy the following formula. Es* / Et*≦7.0 (In the formula, Et* is the complex modulus measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode. Es* is the complex modulus measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.) <Specified air pressure> If the virtual volume V of the tire is 15,000 cm³ or more: 250 (kPa) If the virtual volume V of the tire is less than 15,000 cm³: 0.0152 × V + 22.553 (kPa) The virtual volume V (mm³) of the tire is calculated using the following formula, with respect to the tire's outer diameter Dt (mm), tire's cross-sectional width Wt (mm), rim diameter R (mm), and tire's cross-sectional height H (mm). V={(Dt / 2) 2 - (R / 2) 2}×π×Wt R = Dt - 2H (In the formula, Dt, Wt, and H are all values ​​obtained when the tire is mounted on a standard rim and the internal pressure is at atmospheric pressure.)

3. The tire according to claim 1 or 2, wherein the joint between the tread portion and the sidewall portion is located more than Wt / 4 (mm) outward in the tire width direction from the tire equator.

4. A tire according to any one of claims 1 to 3, having a tread reinforcing layer within the tread portion.

5. A tire according to any one of claims 1 to 4, further comprising a support member on the inner side of the tire cavity of the tread portion and / or on the inner side of the tire cavity of the sidewall portion.

6. The tire according to claim 5, wherein the tensile modulus of the support member is 0.1 to 13.0 GPa.

7. The thermoplastic elastomer composition constituting the sidewall portion is a tire according to any one of claims 1 to 6, wherein the complex modulus Es* satisfies the following formula. 13.0MPa≦Es*≦80.0MPa (In the formula, Es* is the complex modulus of elasticity measured under the conditions of a temperature of 30°C, an initial strain of 10%, a dynamic strain of 1%, a frequency of 10Hz, and the extension mode.)

8. A tire according to any one of claims 1 to 7, wherein the tire's cross-sectional width Wt (mm) and tire's cross-sectional height H (mm) satisfy the following formula. H / Wt×100≧45%

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