Self-sealing tire

Abstract

A self-sealing tire is provided, which has a sealing layer on an inner peripheral surface of the tire, wherein, when a cross-sectional width and an outer diameter of the self-sealing tire at the time when the self-sealing tire is mounted on a standard rim and has an internal pressure of 250 kPa are defined as Wt (unit: mm) and Dt (unit: mm), respectively, Wt and Dt satisfy the following inequality (1): 1600 ≦ (Dt 2 × π / 4) / Wt ≦ 2827.4 (1), and a dynamic complex elastic modulus G* of the sealing layer, which is measured in accordance with ISO 13145, in an atmosphere at 100°C, under a condition that a strain is 100% and a frequency is 0.1 Hz, is 0.50 to 3.50 kPa.

Description

Technical Field

[0001] This invention relates to a self-sealing tire. Background Technology

[0002] Patent document 1 discloses a tire that improves fuel efficiency compared to conventional tires by increasing the tire's outer diameter relative to its contact patch width. However, such a narrow-width, large-diameter tire has a small contact patch, thus making it difficult to ensure handling stability.

[0003] Patent document 2 discloses a tire using a sealing material with excellent tear resistance and sealing performance.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: WO 2012 / 176476

[0007] Patent Document 2: WO 2017 / 094653 Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] The purpose of this invention is to provide a self-sealing tire with improved overall performance in terms of handling stability and airtightness.

[0010] [Methods used to solve problems]

[0011] Further research revealed that in tires with narrow width and large diameter that meet predetermined requirements for tire cross-sectional width and outer diameter, the above problems can be solved by setting the dynamic complex elastic modulus of the sealing layer within a predetermined range.

[0012] That is, the present invention is a self-sealing tire, which includes a sealing layer on the inner circumferential surface of the tire. When the cross-sectional width and outer diameter of the self-sealing tire are defined as Wt (in mm) and Dt (in mm), respectively, and the self-sealing tire is mounted on a standard rim with an internal pressure of 250 kPa, Wt and Dt satisfy the following inequality (1), wherein the dynamic complex elastic modulus G* of the sealing layer, measured according to ISO 13145, in an atmosphere at 100°C, under conditions of 100% strain and a frequency of 0.1 Hz, is 0.50–3.50 kPa.

[0013] 1600≦(Dt 2 ×π / 4) / Wt≦2827.4(1).

[0014] [The effects of the invention]

[0015] According to the present invention, a self-sealing tire with improved overall performance in terms of handling stability and airtightness is provided. Attached Figure Description

[0016] Figure 1 An illustrative diagram illustrating an example of the cross-section of a self-sealing tire.

[0017] Reference Symbol List Detailed Implementation

[0018] As one embodiment of the present invention, the tire is a self-sealing tire having a sealing layer on the inner circumferential surface of the tire. When the cross-sectional width and outer diameter of the self-sealing tire are defined as Wt (in mm) and Dt (in mm), respectively, and the self-sealing tire is mounted on a standard rim with an internal pressure of 250 kPa, Wt and Dt satisfy the following inequality (1), wherein the dynamic complex elastic modulus G* of the sealing layer, measured according to ISO 13145, in an atmosphere at 100°C, under conditions of 100% strain and a frequency of 0.1 Hz, is 0.50–3.50 kPa (preferably 0.55–3.20 kPa, more preferably 0.60–2.90 kPa, and even more preferably 0.65–2.70 kPa):

[0019] 1600≦(Dt 2 ×π / 4) / Wt≦2827.4(1).

[0020] In this invention, the tire cross-sectional width Wt (in mm), tire cross-sectional height Ht (in mm), and tire outer diameter Dt (in mm) are measured with the tire mounted on a standard rim, filled with air to achieve an internal pressure of 250 kPa or more, and without any applied load. Furthermore, "tire cross-sectional width" refers to the maximum width between the outer surfaces of the tire sidewalls, excluding any patterns or characters (if present) on the tire sidewall, under the aforementioned conditions. The tire cross-sectional height Ht is the distance from the bottom surface of the bead portion to the outermost surface of the tread, and is half the difference between the tire outer diameter and the nominal diameter of the rim.

[0021] A "standard rim" refers to the rim specified for each tire within a standards system that includes the standards upon which the tire is based. For example, in JATMA it is a "regular rim," in TRA it is a "design rim," or in ETRTO it is a "measuring rim." Furthermore, if no tire size is specified in the aforementioned standards system, a standard rim refers to a rim that can be fitted to a tire, and whose width is the narrowest among rims with the smallest diameter that will not cause air leakage between the rim and the tire.

[0022] In the self-sealing tire of the present invention, the tire is shaped such that the tire area viewed from the lateral side is greater than the tire's cross-sectional width within a predetermined range. As a result, the heat dissipation performance of the tire sidewall can be improved, and sufficient fuel efficiency can be achieved. Specifically, the self-sealing tire is characterized in that when the tire's cross-sectional width and outer diameter are defined as Wt (in mm) and Dt (in mm), respectively, and the tire is mounted on a standard rim with an internal pressure of 250 kPa, Wt and Dt satisfy the following inequality (1):

[0023] 1600≦(Dt 2 ×π / 4) / Wt≦2827.4(1).

[0024] When the tire has a shape that satisfies inequality (1), it can be adequately ensured that the tire area (in mm²) relative to the tire cross-sectional width Wt (in mm) when viewed from the lateral side is [missing information]. 2 ), that is, [(Dt / 2) 2 ×π)=(Dt 2 [×π / 4)], and the heat dissipation performance of the tire sidewall is improved, thus significantly reducing rolling resistance and achieving good fuel efficiency.

[0025] Here, as Dt increases, the value of inequality (1) increases, and conversely, as Dt decreases, the value decreases. On the other hand, as Wt increases, the value of inequality (1) decreases, and conversely, as Wt decreases, the value increases. Therefore, with this in mind, Dt and Wt can be adjusted to satisfy inequality (1). Furthermore, the value of inequality (1) is preferably 1963.4 or more, more preferably 2000 or more. Furthermore, the value of inequality (1) is preferably 2800 or less, more preferably 2700 or less, and even more preferably 2600 or less.

[0026] Specific examples of tire sizes that satisfy inequality (1) include 125 / 65R19, 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, 195 / 55R20, 205 / 55R16, etc.

[0027] However, when manufacturing tires with the aforementioned shape, the centrifugal force during rolling increases, and the tire radius increases significantly during rolling. As a result, the contact patch pressure becomes uneven, raising concerns about potential deterioration in handling stability. In particular, the wider the tire cross-section width Wt, the greater the difference between the contact patch pressure at the center of the tread and at the tread shoulder, which is believed to easily lead to a deterioration in handling stability.

[0028] Therefore, if the dynamic complex elastic modulus G* of the sealing layer meets the above requirements, the overall performance of the self-sealing tire in terms of handling stability and airtightness will be improved. The reasons for this are not intended to be constrained by any theory, but can be considered as follows.

[0029] By setting a sealing layer with a dynamic complex elastic modulus G* of 0.50 kPa or higher to resist tire torsion, the reaction force against tire torsion is increased, while maintaining the shape of the sealing layer, thus improving handling stability. Furthermore, it is believed that setting the dynamic complex elastic modulus G* of the sealing layer to 3.50 kPa or lower allows for appropriate flowability of the sealing layer, and airtightness can be ensured through tear sealing.

[0030] The self-sealing tire of the present invention preferably has a Dt / G* of 150 or more, more preferably 240 or more, even more preferably 330 or more, even more preferably 420 or more, and particularly preferably 500 or more. Since the self-sealing tire of the present invention has a large tire outer diameter and a small dynamic complex modulus, there is a concern that handling stability performance may deteriorate. Therefore, by reducing the tire outer diameter according to the dynamic complex modulus, handling stability performance can be improved. Furthermore, Dt / G* is preferably 1500 or less, more preferably 1300 or less, even more preferably 1100 or less, and particularly preferably 1000 or less.

[0031] The Wt / G* of the self-sealing tire of the present invention is preferably 400 or less, more preferably 320 or less, even more preferably 300 or less, and particularly preferably 280 or less. Since the self-sealing tire of the present invention has a small tire cross-sectional width and a small dynamic complex modulus, there is a concern that handling stability performance may deteriorate. Therefore, by increasing the tire cross-sectional width according to the dynamic complex modulus, handling stability performance can be improved. Furthermore, Wt / G* is preferably 30 or more, more preferably 40 or more, even more preferably 50 or more, and particularly preferably 60 or more.

[0032] In the self-sealing tire of the present invention, the cross-sectional area of ​​the sealing layer is defined as S (unit: mm). 2When the S / G* is less than 3000, more preferably less than 2000, further preferably less than 1500, further preferably less than 1000, further preferably less than 900, further preferably less than 850, and particularly preferably less than 800. Furthermore, the S / G* is preferably 100 or more, more preferably 150 or more, further preferably 200 or more, further preferably 250 or more, and particularly preferably 300 or more. Since the self-sealing tire of the present invention has a small tire cross-sectional width and a small dynamic complex modulus of elasticity, there is a concern that handling stability performance may deteriorate. Therefore, by increasing the cross-sectional area of ​​the sealing layer according to the dynamic complex modulus of elasticity, it is believed that handling stability performance can be improved, and airtightness performance can also be ensured.

[0033] The G*×S / Wt of the self-sealing tire of the present invention is preferably 30 or less, more preferably 20 or less, even more preferably 10 or less, even more preferably 8.0 or less, and particularly preferably 7.0 or less. Furthermore, G*×S / Wt is preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 1.5 or more. Since the self-sealing tire of the present invention has a small tire cross-sectional width and a small dynamic complex modulus, there is a concern that handling stability performance may deteriorate. Therefore, by increasing the cross-sectional area of ​​the sealing layer according to the dynamic complex modulus, it is believed that handling stability performance can be improved, and airtightness can also be ensured.

[0034] The aspect ratio of the self-sealing tire of the present invention is preferably 40% or more, more preferably 45% or more, even more preferably 47.5% or more, even more preferably 50% or more, even more preferably 52.5% or more, and particularly preferably 55% or more. When the aspect ratio is within the above range, the height of the tire sidewall portion can be increased, and local deformation of the tire can be suppressed, thereby further improving the tire's durability. Furthermore, the aspect ratio (%) is calculated based on the tire's cross-sectional height Ht (in mm) and cross-sectional width Wt (in mm) (with an internal pressure of 250 kPa), by (Ht / Wt) × 100.

[0035] The outer diameter Dt of the tire is preferably 515 mm or more, more preferably 558 mm or more, even more preferably 585 mm or more, and particularly preferably 632 mm or more. Furthermore, the outer diameter Dt of the tire is preferably less than 843 mm, more preferably less than 725 mm, even more preferably less than 707 mm, even more preferably less than 685 mm, and particularly preferably less than 655 mm.

[0036] The tire's cross-sectional width Wt is preferably 115 mm or more, more preferably 125 mm or more, even more preferably 150 mm or more, and particularly preferably 170 mm or more. Furthermore, the tire's cross-sectional width Wt is preferably less than 305 mm, more preferably less than 245 mm, even more preferably less than 210 mm, and particularly preferably less than 200 mm.

[0037] The tire's section height Ht is preferably 37 mm or more, more preferably 60 mm or more, and even more preferably 80 mm or more. Furthermore, the tire's section height Ht is preferably less than 180 mm, more preferably less than 152 mm, and even more preferably less than 115 mm.

[0038] In the self-sealing tire of the present invention, from the perspective of ride comfort and stability during driving, (Dt-2×Ht) is preferably 360 mm or more, more preferably 380 mm or more, further preferably 400 mm or more, and particularly preferably 420 mm or more. On the other hand, from the perspective of tread deformation, it is preferably less than 560 mm, more preferably less than 530 mm, and further preferably less than 510 mm.

[0039] Furthermore, the virtual volume V (in mm) of the tire when it is mounted on a standard rim and the tire pressure is 250 kPa. 3 The cross-sectional width Wt (in mm), outer diameter Dt (in mm), and cross-sectional height Ht (in mm) can be calculated using the following equation (2):

[0040] V = [(Dt / 2)] 2 -{(Dt / 2)-Ht} 2 ]×π×Wt (2).

[0041] The virtual volume V is preferably 1.2 × 10⁻⁶. 7 mm 3 The above is preferred, and more preferably is 1.6 × 10⁻⁶. 7 mm 3 The above is further preferred to be 2.0×10 7 mm 3 That's all. On the other hand, the virtual volume V is preferably less than 8.8 × 10⁻⁶. 7 mm 3 More preferably less than 6.6×10 7 mm 3 Further preferred is less than 4.4×10 7 mm 3 Especially preferred is less than 3.9×10 7 mm 3 .

[0042] Furthermore, in the self-sealing tire of the present invention, the virtual volume V of the tire (in mm) 3 The cross-sectional width Wt (in mm) preferably satisfies the following inequality (3):

[0043] [(V+1.5×10 7 ) / Wt]≦4.02×10 5 (3).

[0044] Thus, by reducing the virtual volume V of the tire by decreasing the cross-sectional width Wt, and by reducing the volume of the tire itself, the outer diameter growth rate caused by centrifugal force can be reduced. Therefore, it is believed that the amount of deformation in the bead portion of the tire sidewall can be reduced, and the rounding of the tread portion can also be suppressed.

[0045] The virtual volume V of the tire (in mm) 3 The cross-sectional width Wt (mm) preferably satisfies the following inequality (4), and even more preferably satisfies the following inequality (5):

[0046] [(V+2.0×10 7 ) / Wt]≦4.02×10 5 (4),

[0047] [(V+2.5×10 7 ) / Wt]≦4.02×10 5 (5).

[0048] The following details the process for manufacturing a self-sealing tire including a sealing layer, as one embodiment of the present invention. However, this description is illustrative and not intended to limit the scope of the invention to the scope of this description. Furthermore, in this specification, numerical ranges indicated by "~" mean values ​​including both ends.

[0049] <Rubber Composition>

[0050] Self-sealing tires can be conventionally manufactured using known methods, such as by mixing the components constituting the sealing material to prepare a sealing material, and then applying the resulting sealing material to the inner circumferential surface of the tire by coating or the like to form a sealing layer. Self-sealing tires have a sealing layer on the radially inner side of the inner liner of the tire. The sealing material is not particularly limited as long as it has adhesive properties, and rubber compositions conventionally used for tire puncture sealing can be used.

[0051] The rubber composition constituting the sealing layer according to the invention (hereinafter, simply referred to as "the rubber composition of the invention") preferably contains butyl rubber as a rubber component. Examples of butyl rubber include butyl rubber (IIR) and halogenated butyl rubber (X-IIR) (e.g., brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR), etc.). Halogenated butyl rubber is preferred. Brominated butyl rubber is particularly suitable for use due to its rapid reaction. Furthermore, granulated butyl rubber is preferred as the butyl rubber. As a result, the butyl rubber can be accurately and appropriately supplied to the continuous kneader, and the sealing material can be manufactured efficiently.

[0052] As a rubber component other than butyl rubber, other components can be used in combination, such as natural rubber (NR), isoprene rubber (IR), diene rubbers such as butadiene rubber (BR), styrene-butadiene rubber (SBR), styrene-isoprene-butadiene rubber (SIBR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), etc. From the perspective of flowability, the content of butyl rubber in 100% by mass of the rubber component is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, further preferably 80% by mass or more, further preferably 81% by mass or more, further preferably 85% by mass or more, further preferably 87% by mass or more, further preferably 90% by mass or more, and particularly preferably 95% by mass or more. Furthermore, the rubber component can be a rubber component consisting solely of butyl rubber.

[0053] The rubber composition of the present invention can be compounded with, for example, composite materials containing at least one functional group with metal coordination capability in their molecular structure. Here, the functional group with metal coordination capability is not particularly limited as long as it possesses metal coordination capability; examples include functional groups containing metal coordinating atoms such as oxygen, nitrogen, sulfur, etc. Specific examples of such functional groups include dithiocarbamic acid groups, phosphate groups, carboxylic acid groups, carbamic acid groups, dithioacid groups, aminophosphate groups, thiol groups, etc. The above functional groups may be contained individually or in combination with two or more of them.

[0054] Examples of coordinating metals for this functional group include, for example, Fe, Cu, Ag, Co, Mn, Ni, Ti, V, Zn, Mo, W, Os, Mg, Ca, Sr, Ba, Al, Si, etc. For example, in the presence of metal atoms with such a functional group (M... 1 In polymer materials containing compounds that are mixed with functional groups (-COO, etc.) with metal coordination ability, each -COO 1 Through coordination binding, therefore a large number of -COOM 1Overlapping, thus forming clusters of metal atoms. Furthermore, based on 100 parts by mass of the polymer component in the polymer material, the aforementioned metal atoms (M... 1 The preferred mixing amount is 0.01 to 200 parts by weight.

[0055] The rubber composition of the present invention preferably comprises a liquid polymer. Examples of liquid polymers include, for example, liquid polybutene, liquid polyisobutylene, liquid polyisoprene, liquid polybutadiene, liquid polyα-olefin, liquid isobutylene, liquid ethylene α-olefin copolymer, liquid ethylene propylene copolymer, and liquid ethylene butene copolymer. Among these, liquid polybutene is preferred because it has good compatibility with butyl rubbers. Examples of liquid polybutene include copolymers that are mainly composed of isobutylene and also have a long-chain hydrocarbon molecular structure (obtained by the reaction of n-butene), and hydrogenated liquid polybutene may also be used.

[0056] From the perspective of maintaining the shape of the sealing material, the kinematic viscosity of the liquid polymer at 100°C is preferably 100 cSt (100 mm³ / s). 2 The viscosity is preferably 200 cSt or higher, more preferably 5000 cSt or higher, and particularly preferably 1000 cSt or higher. Furthermore, from the perspective of airtightness, the kinematic viscosity of the liquid polymer at 100°C is preferably 6000 cSt (6000 mm² / s) or higher. 2 The viscosity is preferably 5500 cSt or less, more preferably 5000 cSt or less, and particularly preferably 4500 cSt or less. Furthermore, in this invention, the kinematic viscosity of the liquid polymer is determined according to ASTM D445.

[0057] From the perspective of airtightness, based on 100 parts by weight of rubber component, the content of liquid polymer is preferably 50 parts by weight or more, more preferably 100 parts by weight or more, and even more preferably 150 parts by weight or more. Furthermore, from the perspective of maintaining the shape of the sealing material, the content of liquid polymer is preferably 400 parts by weight or less, more preferably 350 parts by weight or less, and even more preferably 300 parts by weight or less.

[0058] The rubber composition of the present invention preferably contains inorganic fillers. Examples of inorganic fillers include, for example, carbon black, silica, and mM... 2 ·xSiOy·zH2O(where M) 2The symbol represents at least one metal selected from aluminum, calcium, magnesium, titanium, and zirconium, or an oxide, hydroxide, hydrate, or carbonate of that metal; m represents a value in the range of 1 to 5, x represents a value in the range of 0 to 10, y represents a value in the range of 2 to 5, and z represents a value in the range of 0 to 10. The symbol also represents inorganic fillers, etc. From the perspective of preventing degradation caused by ultraviolet light, carbon black is preferred.

[0059] By mM 2 Specific examples of inorganic fillers represented by ·xSiOy·zH2O include: aluminum hydroxide (Al(OH)3), bauxite (Al2O3, Al2O3·3H2O), clay (Al2O3·2SiO2), kaolin (Al2O3·2SiO2·2H2O), pyrophyllite (Al2O3·4SiO2·H2O), bentonite (Al2O3·4SiO2·2H2O), and aluminum silicate (Al2SiO5, Al4(SiO2)3·5H2O). Calcium aluminum silicate (Al2O3·CaO·2SiO2), calcium hydroxide (Ca(OH)2), calcium oxide (CaO), calcium silicate (Ca2SiO4), calcium magnesium silicate (CaMgSiO4), magnesium hydroxide (Mg(OH)2), magnesium oxide (MgO), talc (MgO·4SiO2·H2O), attapulgite (5MgO·8SiO2·9H2O), magnesium aluminum oxide (MgO·Al2O3), titanium dioxide (TiO2), titanium black (Ti n O 2n-1 In rubber compositions containing such fillers, clusters of filler aggregates are formed. Furthermore, the preferred amount of the filler is 10 to 200 parts by weight per 100 parts by weight of the rubber component.

[0060] There are no particular limitations on carbon black; those commonly used in the tire industry, such as GPF, FEF, HAF, ISAF, and SAF, can be used. Specifically, N110, N115, N120, N125, N134, N135, N219, N220, N231, N234, N293, N299, N326, N330, N339, N343, N347, N351, N356, N358, N375, N539, N550, N582, N630, N642, N650, N660, N683, N754, N762, N765, N772, N774, N787, N907, N908, N990, and N991 can also be used appropriately. In-house synthesized products can also be used. These carbon blacks can be used alone or in combination of two or more.

[0061] From the perspective of suppressing the deterioration of sealing performance caused by ultraviolet radiation, the content of inorganic filler (preferably carbon black) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, based on 100 parts by mass of rubber composition. Furthermore, from the perspective of suppressing the deterioration of sealing performance (caused by an increase in the viscosity of the sealing material), it is preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less.

[0062] (Other compounding agents)

[0063] In addition to the above-mentioned components, the rubber composition of the present invention may also suitably contain compounding agents that are conventional and commonly used in the tire industry, such as oils, resin components, waxes, zinc oxide, stearic acid, antioxidants, crosslinking agents, vulcanization accelerators, etc.

[0064] Examples of oils include processing oils, vegetable oils, and animal fats. Examples of processing oils include alkane-based processing oils, cycloalkane-based processing oils, and aromatic processing oils. Furthermore, as an environmental countermeasure, processing oils with low polycyclic aromatic hydrocarbon (PCA) content can be used. Examples of processing oils with low PCA content include lightly extracted solvates (MES), treated distillate aromatic extracts (TDAE), and heavy cycloalkane oils.

[0065] When formulating the oil mixture, the oil content 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, based on 100 parts by mass of rubber component. Furthermore, this content is preferably 40 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less.

[0066] The resin composition is not particularly limited, and examples include petroleum resins, terpene resins, rosin resins, and phenolic resins commonly used in the tire industry. Petroleum resins are preferred. These resin components can be used alone or in combination of two or more.

[0067] When formulating the resin composition, the resin content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, further preferably 10 parts by mass or more, and particularly preferably 15 parts by mass or more, based on 100 parts by mass of the rubber composition. Furthermore, this content is preferably 100 parts by mass or less, more preferably 60 parts by mass or less, further preferably 40 parts by mass or less, and particularly preferably 30 parts by mass or less.

[0068] When compounding stearic acid, from a processability perspective, the stearic acid content is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, based on 100 parts by mass of rubber component. Furthermore, from a vulcanization rate perspective, this content is preferably 10 parts by mass or less, more preferably 5 parts by mass or less.

[0069] When compounding zinc oxide, from the perspective of maintaining the shape of the sealing material, the zinc oxide content is preferably 1 part by mass or more, more preferably 2 parts by mass or more, further preferably 4 parts by mass or more, and particularly preferably 6 parts by mass or more, based on 100 parts by mass of rubber component. Furthermore, from the perspective of airtightness, this content is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, further preferably 15 parts by mass or less, and particularly preferably 12 parts by mass or less.

[0070] Examples of vulcanizing agents include, for example, sulfur, organic peroxides, alkylphenol / sulfur chloride condensates, hexamethylene-1,6-dithiosulfate sodium dihydrate, and 1,6-bis(N,N'-dibenzylthiocarbamoyldithio)hexane. As sulfur, powdered sulfur, oil-treated sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, and highly dispersed sulfur can be used.

[0071] When compounding vulcanizing agents, from the perspective of suppressing the thermal aging of the sealing layer to ensure airtight performance until the end of the driving period, the content of vulcanizing agent is preferably less than 1.0 part by weight, more preferably less than 0.5 parts by weight, further preferably less than 0.1 parts by weight, and particularly preferably less than 0.01 parts by weight, based on 100 parts by weight of rubber composition. Alternatively, the rubber composition may not contain vulcanizing agents. Furthermore, when using oil-containing sulfur as a vulcanizing agent, the content of the vulcanizing agent should be the total content of pure sulfur contained in the oil-containing sulfur.

[0072] Examples of vulcanization accelerators include, but are not limited to, sulfenamide-based, thiazole-based, thiuram-based, thiourea-based, guanidine-based, dithiocarbamate-based, aldehyde-amine-based, aldehyde-amine-based, imidazoline-based, xanthic acid-based, and quinone dioxime compound (quinone-type compound) vulcanization accelerators. Among these, sulfenamide-based, thiazole-based, and guanidine-based vulcanization accelerators are preferred from the perspective of more appropriately obtaining the desired effect.

[0073] Examples of sulfenamide-based vulcanization accelerators include N-cyclohexyl-2-benzothiazolyl sulfenamide (CBS), N-(tert-butyl)-2-benzothiazolyl sulfenamide (TBBS), N-oxyethylene-2-benzothiazolyl sulfenamide, N,N'-diisopropyl-2-benzothiazolyl sulfenamide, and N,N-dicyclohexyl-2-benzothiazolyl sulfenamide. Examples of thiazole-based vulcanization accelerators include 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide. Examples of thiuram-based vulcanization accelerators include tetramethylthiuram monosulfide, tetramethylthiuram disulfide, and tetrabenzylthiuram disulfide (TBzTD). Examples of guanidine-based vulcanization accelerators include diphenylguanidine (DPG), di-o-tolylguanidine, and o-tolyl biguanide. Examples of dithiocarbamate-based vulcanization accelerators include zinc dimethyl dithiocarbamate (ZnMDC). These vulcanization accelerators can be used alone or in combination of two or more of them.

[0074] When compounding a vulcanization accelerator, the content of the vulcanization accelerator is preferably 8.0 parts by weight or less, more preferably 7.0 parts by weight or less, and even more preferably 6.0 parts by weight or less, based on 100 parts by weight of rubber component. Furthermore, the lower limit of this content can be, but is not particularly limited to, for example, 0.1 parts by weight or more, 0.5 parts by weight or more, 1.0 parts by weight or more, 1.5 parts by weight or more, 2.0 parts by weight or more, or 2.5 parts by weight.

[0075] In addition, from the perspective of suppressing the thermal aging of the sealing layer to ensure airtight performance until the end of the driving period, the content of vulcanization accelerator can be, for example, less than 1.0 parts by weight, less than 0.5 parts by weight, less than 0.1 parts by weight, or less than 0.01 parts by weight, or the rubber composition may not contain vulcanization accelerator.

[0076] Based on 100 parts by weight of rubber composition, the content of thiuram-based vulcanization accelerator is preferably less than 1.0 parts by weight, more preferably less than 0.5 parts by weight, even more preferably less than 0.1 parts by weight, particularly preferably less than 0.01 parts by weight, or the rubber composition may not contain thiuram-based vulcanization accelerator.

[0077] Based on 100 parts by weight of rubber composition, the content of dithiocarbamate-based vulcanization accelerator is preferably less than 1.0 parts by weight, more preferably less than 0.5 parts by weight, even more preferably less than 0.1 parts by weight, particularly preferably less than 0.01 parts by weight, or the rubber composition may not contain dithiocarbamate-based vulcanization accelerator.

[0078] By mixing the above-mentioned materials to prepare a sealing material, and applying the prepared sealing material to the inner circumferential surface of a tire (preferably, the radially inner portion of the inner liner), a self-sealing tire with a sealing layer A on the radially inner side of the inner liner can be manufactured. The mixing of the materials constituting the sealing material can be carried out using, for example, a known continuous kneader. Preferably, a multi-screw kneading extruder, particularly a twin-screw kneading extruder, is used for mixing, either rotating in the same or opposite directions.

[0079] From the perspectives of ease of mixing, extrudability, dispersibility and crosslinking reaction, it is preferable to carry out mixing in a continuous kneader (especially a twin-screw kneading extruder) at a barrel temperature of 30°C (preferably 50°C) to 150°C.

[0080] From the perspective of thorough mixing, the mixing time of the material is preferably 1 to 30 minutes, more preferably 2 to 20 minutes. Furthermore, in this invention, the mixing time refers to the residence time from the time of supply to the continuous kneader (especially a twin-screw kneading extruder) to the time of discharge.

[0081] The temperature of the sealing material discharged from the outlet can be adjusted by changing the screw speed of the continuous kneader (especially a twin-screw kneading extruder) or by setting the temperature controller, and the curing acceleration rate of the sealing material can also be controlled. When the screw speed of the continuous kneader (especially a twin-screw kneading extruder) increases, the kneading properties and material temperature increase. Furthermore, the screw speed does not affect the discharge volume. From the perspective of thorough mixing and controlling the curing acceleration rate, the screw speed is preferably 50–700 rpm, more preferably 50–550 rpm.

[0082] From the perspective of thorough mixing and controlling the curing acceleration rate, the temperature of the sealing material discharged from the outlet of a continuous kneader (especially a twin-screw kneading extruder) is preferably 70–150°C, more preferably 90–130°C. When the temperature of the sealing material is within the above range, the crosslinking reaction begins during coating, allowing the sealing material to have good adhesion to the inner circumferential surface of the tire, and the crosslinking reaction proceeds more appropriately. Therefore, it is possible to manufacture self-sealing tires with high sealing performance without the need for a crosslinking step.

[0083] The sealing material can be applied to the inner circumferential surface of the tire at least on the inner circumferential surface corresponding to the tread portion, and more preferably at least on the inner circumferential surface corresponding to the buffer layer. By omitting the application of the sealing material to the uncoated portions, self-sealing tires with higher productivity can be manufactured. Here, the inner circumferential surface corresponding to the tread portion refers to the inner circumferential surface of the tire located radially inside the tread portion that contacts the road surface, and the inner circumferential surface corresponding to the buffer layer refers to the inner circumferential surface of the tire located radially inside the buffer layer. Furthermore, the buffer layer is a component equipped with cords (e.g., steel cords), which is disposed inside the tread and on the radially outer side of the tire carcass.

[0084] Sealing layer A is preferably formed by continuously and spirally applying a sealing material with a substantially linear shape to the inner circumferential surface of the tire. When the sealing material has a substantially linear shape, a sealing layer A consisting of a single layer of sealing material can be formed by continuously and spirally applying the sealing material to the inner circumferential surface of the tire. When the sealing material has a substantially linear shape, the applied sealing material has a certain thickness, thus preventing the tire's uniformity from deteriorating even with a single layer of sealing material, achieving good weight balance, and enabling the manufacture of a self-sealing tire with good sealing performance. Furthermore, since multiple layers are not required, applying only one layer of sealing material is sufficient, thus enabling the manufacture of self-sealing tires with higher productivity.

[0085] Considering the reasons that this can prevent the uniformity of the tire from deteriorating to achieve good weight balance, and that it can enable the manufacture of self-sealing tires with good sealing performance with better productivity, the number of times the sealing material is wrapped around the inner circumference of the tire is preferably 20 to 70 times, more preferably 20 to 60 times, and even more preferably 35 to 50 times. Here, the number of wrapping times of 2 times means that the sealing material is applied so that it wraps around the inner circumference of the tire twice.

[0086] From the perspective of reliably sealing the puncture hole in a tire, the thickness of the sealing layer A is preferably 1.0 mm or more, more preferably 1.5 mm or more, further preferably 2.0 mm or more, and particularly preferably 2.5 mm or more. Furthermore, the upper limit of the thickness of the sealing layer A is preferably, but not particularly limited to, 10.0 mm or less, more preferably 8.0 mm or less, further preferably 5.0 mm or less, and particularly preferably 4.0 mm or less. In addition, the thickness of the sealing material can be adjusted by adjusting the tire's rotational speed, its movement speed in the tire width direction, and the distance between the nozzle tip and the inner circumferential surface of the tire.

[0087] Preferably, the thickness of sealing layer A is substantially constant. As a result, tire uniformity can be further prevented, and a self-sealing tire with better weight balance can be manufactured. Here, in this specification, substantially constant thickness means that the thickness variation is in the range of 90 to 110% (preferably 95 to 105%, more preferably 98 to 102%, and even more preferably 99 to 101%).

[0088] The cross-sectional area S of the sealing layer A is preferably 50 mm². 2 The above, preferably 100mm 2 The above is further preferred to be 150mm. 2 The above is particularly preferred, with 200mm being the most suitable. 2 That's all. Additionally, the cross-sectional area S of the sealing layer A is preferably 1500 mm². 2 The following is a preferred size: 1200mm 2 Hereinafter, 1000mm is further preferred. 2 Hereinafter, 800mm is further preferred. 2 Hereinafter, 700mm is further preferred. 2 The following is particularly preferred: 600mm 2 the following.

[0089] In this specification, the dynamic complex modulus of elasticity G* refers to the dynamic complex modulus of elasticity (kPa) measured according to ISO 13145, in an atmosphere at 100°C, under conditions of 100% strain and a frequency of 0.1Hz. From the perspective of maintaining the shape of the sealant to improve operational stability, the G* of the sealing layer A is 0.50 kPa or more, preferably 0.55 kPa or more, more preferably 0.60 kPa or more, further preferably 0.65 kPa or more, and particularly preferably 0.70 kPa or more. On the other hand, from the perspective of airtightness, the G* of the sealing layer is 3.50 kPa or less, preferably 3.20 kPa or less, more preferably 2.90 kPa or less, further preferably 2.70 kPa or less, further preferably 2.50 kPa or less, further preferably 2.30 kPa or less, and particularly preferably 2.10 kPa or less.

[0090] Furthermore, the G* value of sealing layer A can be appropriately adjusted based on the content of the liquid polymer, the kinematic viscosity of the liquid polymer, and the zinc oxide content. Specifically, when the liquid polymer content increases, the G* value tends to decrease; conversely, when the liquid polymer content decreases, the G* value tends to increase. When the kinematic viscosity of the liquid polymer increases, the G* value tends to increase; conversely, when the kinematic viscosity of the liquid polymer decreases, the G* value tends to decrease. When the zinc oxide content increases, the G* value tends to increase; conversely, when the zinc oxide content decreases, the G* value tends to decrease.

[0091] The elongation at break (EB) (%) in this specification refers to the elongation at break (elongation at cut) measured according to JIS K 6251:2017 in an atmosphere at 25°C and a tensile speed of 500 mm / s. From the perspective of ensuring airtight performance at low temperatures, the EB of sealing layer A is preferably 500% or more, more preferably 520% ​​or more, and even more preferably 540% or more. Furthermore, there is no particular upper limit for EB.

[0092] In the self-sealing tire of the present invention, a sound-absorbing layer B can be provided on the radially inner side of the inner liner layer. Since the sealing material constituting the sealing layer A has adhesive strength, the sound-absorbing layer B can be easily provided on the radially inner side of the sealing layer A by contacting the sound-absorbing layer B with the sealing layer A.

[0093] As sound-absorbing layer B, any material can be used appropriately, as long as it can achieve a noise suppression effect within the tire cavity. Sound-absorbing layer B is composed of, for example, a porous sponge material. The sponge material is a sponge-like porous structure, for example, a so-called sponge itself with open cells (in which rubber or synthetic resin is foamed), and a mesh structure (in which animal fibers, plant fibers, or synthetic fibers are entwined and connected). Furthermore, "porous structure" includes structures with both open and closed cells. As sound-absorbing layer B, considering noise suppression, lightweight, adjustable foaming, and durability, a sponge material made of polyurethane is appropriately used.

[0094] Example

[0095] The present invention will be described below based on embodiments, but the invention is not limited to these embodiments.

[0096] The various chemicals used in the examples and comparative examples are summarized below.

[0097] Butyl rubber: Bromobutyl 2255 (bromobutyl rubber), manufactured by JSR Corporation.

[0098] Carbon black: DIABLACK H (N330), manufactured by Mitsubishi Chemical Corporation

[0099] Liquid Polymer 1: HV-1900 (Liquid Polybutene, kinematic viscosity at 100°C: 3710 cSt), manufactured by ENEOS Corporation

[0100] Liquid Polymer 2: HV-100 (Liquid Polybutene, kinematic viscosity at 100°C: 220 cSt), manufactured by ENEOS Corporation

[0101] Liquid polymer 3: LUCANT HC-1100 (liquid ethylene-α-olefin copolymer, kinematic viscosity at 100°C: 1100 cSt), manufactured by Mitsui Chemicals Co., Ltd.

[0102] Resin composition: Quintone A100 (aliphatic hydrocarbon resin), manufactured by Zeon Corporation, Japan.

[0103] Zinc oxide: Zinc oxide No. 2, manufactured by Mitsui Metals & Minerals Co., Ltd.

[0104] Stearic acid: Beaded stearic acid "Camellia", manufactured by Nippon Oil Co., Ltd.

[0105] (Examples and Comparative Examples)

[0106] According to the formulations shown in Tables 1 and 2, butyl rubber, carbon black, liquid polymer, resin components, zinc oxide, stearic acid, and vulcanization accelerators as needed were added to a 3L twin-screw kneading extruder. The mixture was kneaded at a barrel temperature of 120–135°C and 200 rpm to prepare sealing materials. The sealing materials (essentially linear shape, thickness: 3 mm, width: 4 mm) were extruded from the twin-screw kneading extruder and continuously and spirally adhered through nozzles to the inner circumferential surface of various tires as shown in Tables 1 (size: 175 / 55R20, rim: 5.5×20J) and 2 (size: 205 / 55R16, rim: 6.5×16J) ​​to form a sealing layer, thus producing test tires. The obtained sealing materials and test tires were evaluated as follows.

[0107] <Determination of Dynamic Complex Elastic Modulus G*>

[0108] For each rubber test piece produced by stamping, the dynamic complex modulus G* was determined using a Premier RPA manufactured by Alpha Technologies, according to ISO 13145, in an atmosphere at 100°C, under conditions of 100% strain and a frequency of 0.1 Hz.

[0109] Tensile Test

[0110] Dumbbell-shaped No. 7 test pieces with a thickness of 1 mm were prepared and cut from the inside of the sealing layer of each test tire so that the tire circumferential direction was the tensile direction. Tensile tests were conducted according to JIS K 6251:2017 in an atmosphere at 25°C and a tensile speed of 500 mm / s, and the elongation at break (EB) was determined. In addition, the thickness direction of the sample was defined as the tire radial direction.

[0111] <Maneuverability and Stability>

[0112] Each test tire was mounted on all wheels of a vehicle (a Japanese-made FF vehicle with a 2000cc engine). The vehicle was driven on a circular test track on a dry asphalt surface, and the lap time was measured. Handling stability was expressed exponentially using the following equation. The results show that the larger the exponent, the better the handling stability. Furthermore, the reference tire, a tire without a sealing layer, had a longer (slower) lap time than the examples and comparative examples. Regarding the reference comparative examples, Table 1 shows the tire of Comparative Example 2, or Table 2 shows the tire of Comparative Example 4.

[0113] (Handling stability performance) = [(Loop time of reference tire - lap time of test tire) / (Loop time of reference tire - lap time of reference comparison tire)] × 100

[0114] <Air tightness performance>

[0115] A self-sealing tire was manufactured using the above method by puncturing it with a nail of 4 mm diameter and 50 mm length, and simultaneously filled with air to an internal pressure of 230 kPa. Three hours later, the internal pressure was measured immediately after removing the nail. The airtightness performance was expressed as an index according to the following equation. For the reference comparison examples, Table 1 shows the tire of Comparative Example 2, or Table 2 shows the tire of Comparative Example 4. The results show that the larger the index, the smaller the internal pressure drop and the better the airtightness performance.

[0116] (Air tightness index) = (internal pressure of each test tire) / (internal pressure of the benchmark comparison example) × 100

[0117] In addition, the target value for the combined performance of handling stability and airtightness (the sum of the handling stability performance index and the airtightness performance index) should be greater than 200.

[0118]

[0119]

[0120]

[0121] As can be seen from the results in Tables 1 and 2, the overall performance of the self-sealing tire of the present invention, in which the tire cross-sectional width, tire outer diameter, and dynamic complex elastic modulus of the sealing layer are set within a predetermined range, is improved in terms of handling stability and airtightness.

[0122] <Implementation Method>

[0123] Examples of embodiments of the present invention are shown below.

[0124] [1] A self-sealing tire, which includes a sealing layer on the inner circumferential surface of the tire, wherein, when the cross-sectional width and outer diameter of the self-sealing tire are defined as Wt (in mm) and Dt (in mm) respectively, and the self-sealing tire is mounted on a standard rim and has an internal pressure of 250 kPa, Wt and Dt satisfy the following inequality (1), wherein the dynamic complex elastic modulus G* of the sealing layer, measured according to ISO 13145, in an atmosphere at 100°C, under conditions of 100% strain and 0.1 Hz frequency, is 0.50 to 3.50 kPa (preferably 0.55 to 3.20 kPa, more preferably 0.60 to 2.90 kPa, and even more preferably 0.65 to 2.70 kPa):

[0125] 1600≦(Dt 2 ×π / 4) / Wt≦2827.4 (1).

[0126] [2] The self-sealing tire described in [1] above, wherein Dt / G* is 150 or more.

[0127] [3] The self-sealing tire described in [2] above, wherein Dt / G* is 240 or more.

[0128] [4] The self-sealing tire according to any one of [1] to [3] above, wherein the cross-sectional area of ​​the sealing layer is defined as S (unit: mm). 2 When ), S / G* is 100 to 3000.

[0129] [5] The self-sealing tire described in [4] above, wherein S / G* is 150 to 900.

[0130] [6] The self-sealing tire according to any one of [1] to [5] above, wherein the cross-sectional area of ​​the sealing layer is defined as S (unit: mm). 2 When ), G*×S / Wt is 0.5~30.

[0131] [7] The self-sealing tire described in [6] above, wherein G*×S / Wt is 1.0 to 10.

[0132] [8] The self-sealing tire according to any one of [1] to [7] above, wherein the aspect ratio of the self-sealing tire is 40% or more (preferably 45% or more, more preferably 50% or more, and even more preferably 55% or more).

[0133] [9] The self-sealing tire according to any one of [1] to [8] above, wherein the outer diameter Dt of the self-sealing tire is less than 843 mm (preferably less than 725 mm, more preferably less than 707 mm, and even more preferably less than 685 mm).

[0134]

[10] The self-sealing tire according to any one of [1] to [9] above, wherein the cross-sectional width Wt of the self-sealing tire is less than 305 mm (preferably less than 245 mm, more preferably less than 210 mm, and even more preferably less than 200 mm).

[0135]

[11] The self-sealing tire according to any one of [1] to

[10] above, wherein when the cross-sectional height of the self-sealing tire is defined as Ht (in mm), and the self-sealing tire is mounted on a standard rim and has an internal pressure of 250 kPa, (Dt-2×Ht) is 360 mm or more (preferably 380 mm or more, more preferably 400 mm or more, and even more preferably 420 mm or more).

[0136]

[12] The self-sealing tire according to any one of [1] to

[11] above, wherein the virtual volume V (in mm) of the space occupied by the self-sealing tire is... 3 The following inequality (3) is satisfied by Wt:

[0137] [(V+1.5×10 7 ) / Wt]≦4.02×10 5 (3).

[0138]

[13] According to the self-sealing tire described in

[12] above, the virtual volume V (unit: mm) of the space occupied by the self-sealing tire 3 The following inequality (4) is satisfied by Wt:

[0139] [(V+2.0×10 7 ) / Wt]≦4.02×10 5 (4).

[0140]

[14] According to the self-sealing tire described in

[13] above, the virtual volume V (unit: mm) of the space occupied by the self-sealing tire 3 The following inequality (5) is satisfied by Wt:

[0141] -Continued-

[0142] [(V+2.5×10 7 ) / Wt]≦4.02×10 5 (5).

[0143] Figure Labels

[0144] A: Sealing layer

[0145] B: Sound-absorbing layer

[0146] Wt: Cross-sectional width of the self-sealing tire

[0147] Dt: Outer diameter of the self-sealing tire

[0148] Ht: Section height of the self-sealing tire

Claims

1. A self-sealing tire, wherein the self-sealing tire has a sealing layer on the inner circumferential surface of the tire, wherein, When the cross-sectional width and outer diameter of the self-sealing tire are defined as Wt, in mm and Dt, in mm respectively, and the self-sealing tire is mounted on a standard rim with an internal pressure of 250 kPa, Wt and Dt satisfy the following inequality (1): 1600 ≦ (Dt) 2 ×π / 4) / Wt≦ 2827.4 (1), and The dynamic complex elastic modulus of the sealing layer was measured according to ISO 13145, in an atmosphere at 100°C, under conditions of 100% strain and a frequency of 0.1Hz. The range is 0.50~3.50 kPa; For 240 or above, When the cross-sectional area of ​​the sealing layer is defined as S, the unit is mm. 2 hour, The range is 100 to 3000. The value is 1.0~10. The elongation at break of the sealing layer is 500% or more.

2. The self-sealing tire according to claim 1, wherein, The range is 150 to 900.

3. The self-sealing tire according to claim 1, wherein, The aspect ratio of the self-sealing tire is 40% or higher.

4. The self-sealing tire according to claim 1, wherein, The outer diameter Dt of the self-sealing tire is less than 843 mm.

5. The self-sealing tire according to claim 1, wherein, The cross-sectional width Wt of the self-sealing tire is less than 305 mm.

6. The self-sealing tire according to claim 1, wherein, When the cross-sectional height of a self-sealing tire is defined as Ht, in mm, and the self-sealing tire is mounted on a standard rim with an internal pressure of 250 kPa, (Dt-2×Ht) is 360 or more.

7. The self-sealing tire according to claim 1, wherein, The virtual volume V occupied by the self-sealing tire is in mm. 3 The following inequality (3) is satisfied by Wt: [(V+1.5×10 7 ) / Wt] ≦ 4.02×10 5 (3), In the formula, the virtual volume V of the tire is calculated based on the cross-sectional width Wt (in mm), outer diameter Dt (in mm), and cross-sectional height Ht (in mm) using the following equation: V=[(Dt / 2) 2 -{(Dt / 2)-Ht} 2 ]×π×Wt。 8. The self-sealing tire according to claim 7, wherein, The virtual volume V occupied by the self-sealing tire is in mm. 3 And Wt satisfies the following inequality (4): [(V+2.0×10 7 ) / Wt] ≦ 4.02×10 5 (4)。 9. The self-sealing tire according to claim 8, wherein, The virtual volume V occupied by the self-sealing tire is in mm. 3 And Wt satisfies the following inequality (5): [(V+2.5×10 7 ) / Wt] ≦ 4.02×10 5 (5)。

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