Pneumatic tire and manufacturing method for the same

Abstract

To provide a pneumatic tire configured to be able to suppress oxygen permeating through an inner liner layer from deteriorating a belt layer, and a manufacturing method for the same.SOLUTION: A pneumatic tire comprises a tread part 1 in an annular shape extending in a tire circumferential direction, a pair of side wall parts 2 arranged at both sides of the tread part 1, and a pair of bead parts 3 arranged inside in a tire radial direction of the side wall parts 2, in which a carcass layer 4 is hung between the pair of bead parts, a belt layer 7 is arranged at an outer periphery side of the carcass layer 4 in the tread part 1, and an inner liner layer 9 is arranged along the carcass layer 4. A sealant layer 20 is formed on an inner surface 10 of the tire in the tread part 1, where sealant of the sealant layer 20 is composed of silicone-based compositions and a gas permeation suppressing layer 25 is laminated inside in a tire radial direction of the sealant layer 20.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pneumatic tire having a sealant layer on the inner surface of the tire in the tread portion, and a manufacturing method thereof, and more particularly to a pneumatic tire that can suppress deterioration of a belt layer due to oxygen that has permeated an inner liner layer, and a manufacturing method thereof. [Background technology]

[0002] It has been proposed to provide a sealant layer in a pneumatic tire radially inward of an inner liner layer in the tread portion of the tire. In such a pneumatic tire, when a foreign object such as a nail penetrates the tread portion, the sealant flows into the through-hole, thereby suppressing a decrease in air pressure and enabling the tire to continue running.

[0003] Conventionally, sealants constituting a sealant layer have generally been rubber compositions mainly containing butyl rubber (see, for example, Patent Documents 1 to 3). Examples of butyl rubber include butyl rubber (IIR) and halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR). Such sealants are heated to a high temperature to soften them and then applied to the inner surface of a tire (see, for example, Patent Document 4).

[0004] However, in a pneumatic tire having a sealant layer on the inner surface of the tread portion, the weight of the sealant layer causes the tread portion to rise significantly during running, which causes significant strain in the tread portion and makes the tread portion prone to heat generation. When the tread portion generates a large amount of heat, air easily permeates the inner liner layer, and the oxygen that has permeated the inner liner layer deteriorates the belt layer, which in turn causes the belt layer to easily separate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6583456 [Patent Document 2] Patent No. 6620851 [Patent Document 3] Patent No. 7319533 [Patent Document 4] Patent No. 6124967 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a pneumatic tire that can suppress deterioration of a belt layer due to oxygen that has permeated through an inner liner layer, and a method for manufacturing the same. [Means for solving the problem]

[0007] In order to achieve the above object, a pneumatic tire of the present invention includes a tread portion extending in a circumferential direction of the tire to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed radially inward of the sidewall portions, wherein a carcass layer is mounted between the pair of bead portions, a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer is disposed along the carcass layer; The tire is characterized in that a sealant layer is formed on the inner surface of the tire in the tread portion, the sealant of the sealant layer is made of a silicone-based composition, and a gas permeation suppression layer is laminated on the radially inner side of the sealant layer.

[0008] In order to achieve the above object, a method for manufacturing a pneumatic tire according to the present invention is a method for manufacturing the above-mentioned pneumatic tire, comprising: After manufacturing a pneumatic tire excluding the sealant layer and the gas permeation suppressing layer, The present invention is characterized in that a sealant made of a silicone-based composition is applied to the inner surface of the tire in the tread portion to form the sealant layer, and the gas permeation suppression layer is attached to the tire radially inward side of the sealant layer. [Effects of the Invention]

[0009] In the present invention, a sealant layer is formed on the tire inner surface in the tread portion, the sealant of the sealant layer is composed of a silicone-based composition, and a gas permeation suppressing layer is laminated on the tire radially inward side of the sealant layer. Therefore, even if the sealant layer causes significant heat generation in the tread portion during driving, causing air inside the tire to easily permeate through the inner liner layer, the gas permeation suppressing layer laminated on the sealant layer blocks the movement of air and suppresses deterioration of the belt layer due to oxygen that has permeated through the inner liner layer. This improves the durability of the pneumatic tire. In particular, a sealant composed of a silicone-based composition exhibits good puncture sealing properties but also has the property of easily allowing oxygen to permeate. Therefore, by blocking the movement of air with the gas permeation suppressing layer, deterioration of the belt layer can be effectively suppressed. Furthermore, a sealant composed of a silicone-based composition can be applied at low temperatures; for example, the temperature of the sealant applied to the tire inner surface can be lowered to below 70°C. This has the advantage of reducing the thermal effects on the tire and preventing deterioration of tire performance. Furthermore, when a gas permeation suppression layer is laminated on the inner side of the sealant layer in the tire radial direction, it is possible to avoid the inconvenience of foreign matter adhering to the sealant layer and deteriorating its appearance.

[0010] In the present invention, the oxygen permeability of the gas permeation suppression layer is preferably lower than that of the inner liner layer. In particular, the oxygen permeability of the gas permeation suppression layer is preferably 12×10 -10 cc·cm / cm 2·sec·cmHg or less. By lowering the oxygen permeability of the gas permeation suppression layer, it is possible to reduce the thickness of the gas permeation suppression layer and suppress weight gain while suppressing oxygen permeation. Oxygen permeability is measured in accordance with JIS-K7126-1 at a temperature of 30°C.

[0011] In the present invention, the gas permeation suppression layer is preferably a resin film. Because a resin film can satisfy the above-mentioned oxygen permeability requirement, the gas permeation suppression layer can be made thinner and weight increase can be suppressed while suppressing oxygen permeation.

[0012] In the present invention, the width of the gas permeation suppression layer is preferably in the range of 80% to 120% of the width of the sealant layer. By making the width of the gas permeation suppression layer sufficiently larger than the width of the sealant layer, deterioration of the belt layer can be sufficiently suppressed. Furthermore, by not making the width of the gas permeation suppression layer excessively large, peeling of the gas permeation suppression layer from the sealant layer can be prevented.

[0013] In the present invention, the gas permeation suppressing layer preferably has a uniform thickness in the range of 5 μm to 500 μm along the tire width direction. This makes it possible to suppress weight gain while suppressing oxygen permeation. Furthermore, a gas permeation suppressing layer having this thickness can be easily attached to a sealant layer.

[0014] In the present invention, it is preferable that the thickness of the inner liner layer at the portion overlapping with the gas permeation suppression layer is smaller than the thickness of the other portion. Because oxygen permeation is suppressed in the region where the gas permeation suppression layer is present, it is possible to make the thickness of the inner liner layer at the portion overlapping with the gas permeation suppression layer smaller than the thickness of the other portion, thereby achieving weight reduction.

[0015] In the present invention, it is preferable that an adhesive layer be interposed between the gas permeation suppression layer and the sealant layer. By interposing an adhesive layer between the gas permeation suppression layer and the sealant layer, peeling of the gas permeation suppression layer can be effectively prevented.

[0016] In the present invention, the width of the sealant layer is preferably 90% or more of the width of the belt layer located at the innermost position in the tire radial direction. In particular, it is preferable that the end of the sealant layer is located outward in the tire width direction than the end of the belt layer located at the innermost position in the tire radial direction. By making the width of the sealant layer sufficiently large, sufficient puncture sealing performance can be ensured.

[0017] In the present invention, the thickness of the sealant layer is preferably in the range of 2.0 mm to 5.0 mm, which ensures puncture sealing performance while reducing distortion caused by rising of the tread portion during high-speed driving and maintaining good durability.

[0018] In the present invention, the sealant layer preferably has a tan δ at 100°C in the range of 0.2 to 0.6. This optimizes the flow characteristics of the sealant layer during driving, enabling it to maintain good puncture sealing and flow resistance. The loss tangent tan δ is measured in accordance with JIS-K6394 using a viscoelasticity spectrometer in a tensile deformation mode under conditions of a temperature of 100°C, a frequency of 10 Hz, an initial strain of 10%, and a dynamic strain of ±2%.

[0019] In the present invention, the silicone composition is preferably a two-component curing silicone, which has low viscosity immediately after mixing the two components, making it possible to apply the composition even at low temperatures.

[0020] According to the method for manufacturing a pneumatic tire according to the present invention, the pneumatic tire described above can be manufactured by manufacturing a pneumatic tire excluding the sealant layer and the gas permeation suppressing layer, applying a sealant made of a silicone-based composition to the inner surface of the tire in the tread portion to form a sealant layer, and attaching the gas permeation suppressing layer to the radially inward side of the sealant layer.

[0021] In the method for manufacturing a pneumatic tire according to the present invention, when a sealant made of a silicone composition is applied to the inner surface of the tire in the tread portion to form a sealant layer, it is preferable that the temperature of the sealant applied to the inner surface of the tire be lower than 70° C. This reduces the effect of heat on the tire and prevents deterioration of tire performance.

[0022] In the method for manufacturing a pneumatic tire according to the present invention, it is preferable to attach the gas permeation suppressing layer to the sealant layer before the sealant layer is cured, thereby improving the integrity of the sealant layer and the gas permeation suppressing layer and suppressing peeling of the gas permeation suppressing layer. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view showing a main part of the pneumatic tire of FIG. [Figure 3] 2 is a cross-sectional view illustrating a method for manufacturing the pneumatic tire of FIG. 1. [Figure 4] 2 is a plan view showing a sealant layer formed on the inner surface of the tire in the tread portion of the pneumatic tire of FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: Figures 1 and 2 show a pneumatic tire according to an embodiment of the present invention.

[0025] As shown in FIG. 1, the pneumatic tire of this embodiment includes a tread portion 1 extending circumferentially in a ring shape, a pair of sidewall portions 2, 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3, 3 arranged radially inward of the sidewall portions 2.

[0026] A carcass layer 4 is mounted between a pair of bead portions 3, 3. This carcass layer 4 includes a plurality of carcass cords extending in the tire radial direction, and is folded back from the inside to the outside of the tire around a bead core 5 disposed in each bead portion 3. A bead filler 6 made of a rubber composition and having a triangular cross section is disposed on the outer periphery of the bead core 5.

[0027] On the other hand, multiple belt layers 7 are embedded on the outer peripheral side of the carcass layer 4 in the tread portion 1. These belt layers 7 include multiple belt cords that are inclined with respect to the tire circumferential direction, and are arranged so that the belt cords cross each other between the layers. The multiple belt layers 7 include a first belt layer 7A located on the innermost side in the tire radial direction and a second belt layer 7B located on the outer side of the first belt layer 7A, and the width of the first belt layer 7A is wider than the width of the second belt layer 7B. In the belt layers 7, the inclination angle of the belt cords with respect to the tire circumferential direction is set in the range of 10° to 40°, for example. Steel cords are preferably used as the belt cords of the belt layers 7.

[0028] At least one belt cover layer 8 is arranged on the outer periphery of the belt layer 7, with the aim of improving high-speed durability, and is made up of reinforcing cords arranged at an angle of, for example, 5° or less relative to the tire circumferential direction. This belt cover layer 8 preferably has a jointless structure in which a strip material made of at least one reinforcing cord that has been aligned and rubber-coated is continuously wound at an angle of substantially 0° relative to the tire circumferential direction. The reinforcing cord of the belt cover layer 8 is preferably an organic fiber cord such as nylon or polyethylene terephthalate (PET).

[0029] The tire internal structure described above shows a typical example of a pneumatic tire, but is not limited thereto. An inner liner layer 9 (air permeation prevention layer) made of, for example, a butyl-based rubber composition is disposed inside the carcass layer 4, and the inner surface of the inner liner layer 9 forms the tire inner surface 10. Various grooves, including a plurality of main grooves 11 extending in the tire circumferential direction, are formed in the tread portion 1.

[0030] In the pneumatic tire described above, a sealant layer 20 is formed continuously in the tire circumferential direction on the tire inner surface 10 in the tread portion 1. The center position of the sealant layer 20 in the tire width direction preferably coincides with the tire equator CL, but the center position may be offset from the tire equator CL to either side in the tire width direction. The distance in the tire width direction between the center position of the sealant layer 20 in the tire width direction and the tire equator CL is preferably 10 mm or less, more preferably 5 mm or less. This prevents the sealant layer 20 from adversely affecting tire balance. The sealant layer 20 has a structure in which, for example, a sealant strip 21 is spirally arranged along the tire circumferential direction (see FIG. 4). The sealant of the sealant layer 20 is composed of a silicone-based composition. The silicone-based composition includes a synthetic polymer compound having a main skeleton formed by siloxane bonds.

[0031] Furthermore, a gas permeation suppressing layer 25 is laminated around the entire circumference of the tire on the inner side of the sealant layer 20 in the tire radial direction. Because the gas permeation suppressing layer 25 is laminated on the inner side of the sealant layer 20 in the tire radial direction, even if the weight of the sealant layer 20 causes the tread portion 1 to rise significantly during running, resulting in greater strain in the tread portion 1 and increased heat generation in the tread portion 1, making it easier for air inside the tire to permeate the inner liner layer 9, the gas permeation suppressing layer 25 laminated on the sealant layer 20 blocks the movement of air and suppresses deterioration of the belt layer 7 due to oxygen that has permeated the inner liner layer 9. This improves the durability of the pneumatic tire. In particular, a sealant made of a silicone-based composition exhibits good puncture sealing properties but also has the property of easily allowing oxygen to permeate. Therefore, by blocking the movement of air with the gas permeation suppressing layer 25, deterioration of the belt layer 7 can be effectively suppressed. Furthermore, a sealant made from a silicone-based composition can be applied at low temperatures, and for example, the temperature of the sealant applied to the tire inner surface 10 can be lowered to below 70°C, which has the advantage of reducing the thermal effects on the tire and preventing deterioration of tire performance. Furthermore, by laminating the gas permeation-suppressing layer 25 on the inner side of the sealant layer 20 in the tire radial direction, it is possible to avoid the inconvenience of foreign matter adhering to the sealant layer 20 and deteriorating its appearance.

[0032] In the above pneumatic tire, the oxygen permeability of the gas permeation suppression layer 25 is preferably lower than the oxygen permeability of the inner liner layer 9. In particular, the oxygen permeability of the gas permeation suppression layer 25 is preferably 12×10 -10 cc·cm / cm 2 ·sec·cmHg or less. By lowering the oxygen permeability of the gas permeation suppression layer 25, it is possible to reduce the thickness of the gas permeation suppression layer 25 and suppress weight increase while suppressing oxygen permeation. In particular, the oxygen permeability of the gas permeation suppression layer 25 is preferably 1.2×10 -10 cc·cm / cm 2 It is desirable that it is less than 1 / sec / cmHg.

[0033] In the above pneumatic tire, a rubber sheet or a resin film can be used, but a resin film is particularly preferable, as the gas permeation suppression layer 25. A resin film can satisfy the oxygen permeability requirements described above, and therefore the gas permeation suppression layer 25 can be made thinner and weight increase can be suppressed while suppressing oxygen permeation.

[0034] The resin film can be made of a thermoplastic resin or a thermoplastic elastomer composition in which an elastomer is dispersed in a thermoplastic resin.

[0035] Examples of the thermoplastic resin include polyolefin resins (e.g., polyethylene (PE) and polypropylene (PP)), polyamide resins (e.g., nylon 6 (N6), nylon 66 (N66), nylon 46 (N46), nylon 11 (N11), nylon 12 (N12), nylon 610 (N610), nylon 612 (N612), nylon 6 / 66 copolymer (N6 / 66), nylon 6 / 66 / 610 copolymer (N6 / 66 / 610), nylon MXD6 (MXD6), nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer), and the like. copolymers, nylon 66 / PPS copolymers)] and their N-alkoxyalkylated products [e.g., methoxymethylated nylon 6, methoxymethylated nylon 6 / 610 copolymers, methoxymethylated nylon 612], polyester resins [e.g., polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), PET / PEI copolymers, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystal polyesters, polyoxyalkylene diimide diacid / polybutylene terephthalate aromatic polyesters such as acrylate copolymers], polynitrile resins [for example, polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymers (AS), (meth)acrylonitrile / styrene copolymers, (meth)acrylonitrile / styrene / butadiene copolymers], polymethacrylate resins [for example, polymethyl methacrylate (PMMA), polyethyl methacrylate], polyvinyl resins [for example, polyvinyl acetate, polyvinyl alcohol (PVA), vinyl alcohol / ethylene copolymers (EVOH), polychlorinated Preferred examples of the resin that can be used include polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, vinylidene chloride / methyl acrylate copolymer, vinylidene chloride / acrylonitrile copolymer), cellulose-based resins (e.g., cellulose acetate, cellulose acetate butyrate), fluorine-based resins (e.g., polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE)), and imide-based resins (e.g., aromatic polyimide (PI)).In particular, resin films made of polyethylene, polyvinyl chloride, and polyvinylidene chloride are preferred because they are less permeable to oxygen. For example, the oxygen permeability of butyl rubber is 13 x 10. -10 cc·cm / cm 2 ·sec·cmHg, whereas for polyethylene it is 11×10 -10 cc·cm / cm 2 ·sec·cmHg, and for polyvinyl chloride it is 1.2 × 10 -10 cc·cm / cm 2 ·sec·cmHg~6×10 -10 cc·cm / cm 2 ·sec·cmHg, and for polyvinylidene chloride it is 0.05×10 -10 cc·cm / cm 2 ·sec·cmHg.

[0036] Examples of the elastomer include diene rubbers and their hydrogenated products [e.g., natural rubber (NR), isoprene rubber (IR), epoxidized natural rubber, styrene butadiene rubber (SBR), butadiene rubber (BR, high cis BR and low cis BR), nitrile rubber (NBR), hydrogenated NBR, hydrogenated SBR], olefin rubbers [e.g., ethylene propylene rubber (EPDM, EPM), maleic acid modified ethylene propylene rubber (M-EPM), butyl rubber (IIR), copolymers of isobutylene and aromatic vinyl or diene monomers, acrylic rubber (ACM), ionomers], halogen-containing rubbers [e.g., Br-IIR, Cl-IIR, brominated isobutylene-paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydride rubber], and the like. Preferably usable elastomers include polyethylene rubber (CHR), chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene rubber (CM), maleic acid-modified chlorinated polyethylene rubber (M-CM), silicone rubber (e.g., methyl vinyl silicone rubber, dimethyl silicone rubber, methyl phenyl vinyl silicone rubber), sulfur-containing rubber (e.g., polysulfide rubber), fluororubber (e.g., vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, tetrafluoroethylene-propylene rubber, fluorine-containing silicone rubber, fluorine-containing phosphazene rubber), and thermoplastic elastomer (e.g., styrene-based elastomer, olefin-based elastomer, ester-based elastomer, urethane-based elastomer, polyamide-based elastomer).

[0037] In the above pneumatic tire, the width Wf of the gas permeation suppression layer 25 is preferably in the range of 80% to 120% of the width Ws of the sealant layer 20. By making the width Wf of the gas permeation suppression layer 25 sufficiently larger than the width Ws of the sealant layer 20, deterioration of the belt layer 7 can be sufficiently suppressed. However, if the width Wf of the gas permeation suppression layer 25 is greater than 120% of the width Ws of the sealant layer 20, the unbonded portions of the gas permeation suppression layer 25 will be displaced during running, making it more likely for the gas permeation suppression layer 25 to peel off from the sealant layer 20. In particular, it is desirable for the width Wf of the gas permeation suppression layer 25 to be in the range of 90% to 110% of the width Ws of the sealant layer 20.

[0038] In the above pneumatic tire, as shown in Fig. 2, the thickness Tf of the gas permeation suppression layer 25 is preferably uniform along the tire width direction and in the range of 5 µm to 500 µm. This makes it possible to suppress weight gain while suppressing oxygen permeation. Furthermore, the gas permeation suppression layer 25 having the above thickness Tf also has good workability in attaching to the sealant layer 20. Here, if the thickness Tf of the gas permeation suppression layer 25 is less than 5 µm, the effect of suppressing oxygen permeation is reduced, and the workability in attaching the gas permeation suppression layer 25 is reduced, making the gas permeation suppression layer 25 more likely to peel off during driving. Conversely, if it is greater than 500 µm, it will cause weight gain. In particular, the thickness Tf of the gas permeation suppression layer 25 is preferably in the range of 10 µm to 100 µm.

[0039] In the above pneumatic tire, it is preferable that the thickness T1 of the inner liner layer 9 at the portion overlapping with the gas permeation suppression layer 25 is smaller than the thickness T2 of the remaining portion (see FIG. 2). Because oxygen permeation is suppressed in the region where the gas permeation suppression layer 25 is present, it is possible to make the thickness T1 of the inner liner layer 9 at the portion overlapping with the gas permeation suppression layer 25 smaller than the thickness T2 of the remaining portion, thereby achieving weight reduction. The thicknesses T1 and T2 of the inner liner layer 9 are the average thicknesses in each region. In particular, it is preferable that the thickness T1 of the inner liner layer 9 at the portion overlapping with the gas permeation suppression layer 25 be in the range of 50% to 90% of the thickness T2 of the remaining portion.

[0040] In the above pneumatic tire, it is preferable that an adhesive layer 26 be interposed between the gas permeation suppression layer 25 and the sealant layer 20. By interposing the adhesive layer 26 between the gas permeation suppression layer 25 and the sealant layer 20, peeling of the gas permeation suppression layer 25 can be effectively prevented. An acrylic adhesive is an example of a constituent material of such an adhesive layer 26. The adhesive layer 26 can be applied to the surface of the gas permeation suppression layer 25 to be adhered.

[0041] In the above pneumatic tire, as shown in Fig. 1, the width Ws of the sealant layer 20 is preferably 90% or more of the width Wb of the belt layer 7A located at the innermost position in the tire radial direction. In particular, it is preferable that the end of the sealant layer 20 is located outward in the tire width direction from the end of the belt layer 7A located at the innermost position in the tire radial direction. By making the width Ws of the sealant layer 20 sufficiently larger than the width Wb of the belt layer 7A, sufficient puncture sealing performance can be ensured. Here, if the width Ws of the sealant layer 20 is less than 90% of the width Wb of the belt layer 7A, the puncture sealing performance will be reduced.

[0042] In the pneumatic tire, as shown in FIG. 2, the thickness S of the sealant layer 20 is preferably in the range of 2.0 mm to 5.0 mm. This ensures puncture sealing performance while reducing distortion caused by tread swelling during high-speed driving, thereby maintaining excellent durability. Here, if the thickness S of the sealant layer 20 is less than 2.0 mm, puncture sealing performance will be reduced. Conversely, if the thickness S of the sealant layer 20 is greater than 5.0 mm, distortion caused by tread swelling during high-speed driving will be increased, resulting in a reduced improvement in durability. The thickness S of the sealant layer 20 is the average thickness of the entire tire. The average thickness of the sealant layer 20 can be calculated, for example, by CT scanning a tire meridian cross section at eight locations around the tire circumference, and measuring the thickness of the sealant layer 20 at five points in each image: the tire equator, outer edge positions (on both sides) 10 mm inward in the tire width direction from the edge of the sealant layer 20, and intermediate positions (on both sides) between the tire equator and outer edge positions. This is a total of 40 measurements.

[0043] In the above pneumatic tire, the tan δ of the sealant layer 20 at 100°C is preferably in the range of 0.2 to 0.6. This optimizes the flow characteristics of the sealant layer 20 during running, and enables good puncture sealing and flow resistance to be maintained. If the tan δ of the sealant layer 20 at 100°C is less than 0.2, the puncture sealing performance will be reduced, and conversely, if it is greater than 0.6, the sealant will easily flow.

[0044] The above-described pneumatic tire can be manufactured by the following method. First, a pneumatic tire is manufactured as described above, which includes a tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3, with a belt layer 7 and a belt cover layer 8 embedded in the tread portion 1. Next, a sealant made of a silicone-based composition is applied to the tire inner surface 10 of the tread portion 1 to form a sealant layer 20. Thereafter, the gas permeation suppressing layer 25 is attached to the tire radially inward side of the sealant layer 20, thereby manufacturing the above-described pneumatic tire. In particular, when the gas permeation suppressing layer 25 is attached to the sealant layer 20 before the sealant layer 20 cures, the integrity between the sealant layer 20 and the gas permeation suppressing layer 25 is improved, and peeling of the gas permeation suppressing layer 25 can be suppressed.

[0045] FIG. 3 shows a specific manufacturing method for the pneumatic tire of FIG. 1, and FIG. 4 shows a sealant layer formed on the tire inner surface in the tread portion. In FIG. 3, a sealant extrusion device 31 mixes sealants supplied from pumps 32 and 33 and continuously discharges the mixed sealant as a strip 21 from a nozzle 34. The sealant extrusion device 31 is configured so that the position of the nozzle 34 can be freely changed. Therefore, by moving the nozzle 34 in the axial direction of the tire while rotating the tire from a state in which the nozzle 34 is close to the tire inner surface 10, the sealant strip 21 can be arranged spirally on the tire inner surface 10 while being inclined with respect to the tire circumferential direction Tc (see FIG. 4). The spirally arranged sealant strips 21 are in close contact with each other at their circumferential portions. The spirally arranged sealant strips 21 are integrated to form the sealant layer 20.

[0046] In the pneumatic tire described above, a sealant layer 20 is formed on the tire inner surface 10 of the tread portion 1, with a sealant strip 21 spirally arranged along the tire circumferential direction. Because the sealant is composed of a silicone-based composition, the circumferential portions of the sealant strip 21 fit together easily during the curing reaction of the silicone-based composition, improving the integrity of the circumferential portions of the sealant strip 21, thereby improving the sealing performance of the sealant layer 20. Furthermore, because the circumferential portions of the sealant strip 21 are well-integrated, the sealant layer 20 is less likely to flow toward the center of the tire width direction due to centrifugal force generated during tire rotation, which also contributes to improved sealing performance. Furthermore, using a silicone-based composition as the sealant for the sealant layer 20 has the advantages of excellent weather resistance and low temperature dependency of physical properties.

[0047] Because silicone-based compositions have good fluidity even at low temperatures, it is preferable to set the temperature of the sealant applied to the tire inner surface 10 to below 70°C. This reduces the thermal effects on the tire and prevents deterioration of tire performance. If this temperature is 70°C or higher, the thermal effects on the tire will be significant, causing deterioration of tire performance. In particular, it is desirable that the temperature of the sealant applied to the tire inner surface 10 be preferably 5°C to 40°C, more preferably 10°C to 35°C, and even more preferably 15°C to 30°C. Because such temperatures are below the heat resistance temperature of the resin film that constitutes the gas permeation suppression layer 25, it becomes possible to attach the resin film that constitutes the gas permeation suppression layer 25 to the sealant layer 20 immediately after the sealant is applied.

[0048] The silicone-based composition constituting the sealant of the sealant layer 20 can be a one-component curing silicone or a two-component curing silicone, with two-component curing silicone being particularly preferred. Examples of one-component curing silicones include moisture-curing silicone. Two-component curing silicones are composed of a first component and a second component, and mixing these components initiates a curing reaction, ensuring the stability of the sealant layer 20 after curing. In the above-described device, the first component and the second component of the two-component curing silicone are supplied from pumps 32 and 33, respectively. Two-component curing silicones have low viscosity immediately after mixing, allowing them to be applied even at low temperatures. In particular, two-component curing silicones that take 5 days or more to fully cure are preferred.

[0049] Two-component curing silicones are composed of, for example, a condensation-curable silyl-terminated polymer, a silane crosslinker, a condensation catalyst, a filler, and the like. Examples of condensation-curable silyl-terminated polymers include polydialkylsiloxanes, alkylphenylsiloxanes, organic polymers having silyl groups (e.g., silyl polyethers, silyl acrylates), and polyisobutylenes having silyl groups. Examples of silane crosslinkers include alkoxy-functional silanes, oximosilanes, acetoxysilanes, and enoxysilanes. Examples of fillers include iron oxide, titanium dioxide, carbon black, and talc. Examples of condensation catalysts include titanates and zirconates. These condensation-curable silyl-terminated polymers, silane crosslinkers, condensation catalysts, and fillers are stored in a first and second liquid form in a combination that does not promote a curing reaction, and are mixed when used. [Example]

[0050] In a pneumatic tire having a tire size of 255 / 45R21, which is provided with a tread portion, a pair of sidewall portions, and a pair of bead portions, a carcass layer is mounted between the pair of bead portions, a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer is disposed along the carcass layer, a sealant layer is formed on the inner surface of the tire in the tread portion, and the constituent material of the sealant layer, the presence or absence of a gas permeation suppressing layer (resin film), the oxygen permeability of the gas permeation suppressing layer, and the ratio of the width Wf of the gas permeation suppressing layer to the width Ws of the sealant layer (Wf / Ws×10 0%), the thickness Tf of the gas permeation suppressing layer, the relationship between the thickness T1 of the inner liner layer overlapping with the gas permeation suppressing layer and the thickness T2 of the other portion, the ratio (Ws / Wb × 100%) of the width Wf of the sealant layer to the width Wb of the belt layer positioned radially innermost in the tire, the thickness S of the sealant layer, the tan δ of the sealant layer at 100°C, the sealant application temperature, the presence or absence of an adhesive layer between the gas permeation suppressing layer and the sealant layer, and the timing of application of the gas permeation suppressing layer were varied as shown in Tables 1 and 2 to produce tires of Conventional Example, Comparative Example, and Examples 1 to 23.

[0051] Butyl rubber or two-component curing silicone (SST-26 manufactured by DOW) was used as the constituent material of the sealant layer. Furthermore, with regard to the timing of applying the gas permeation suppression layer, when the gas permeation suppression layer was applied after the sealant layer cured it was indicated as "after curing," and when the gas permeation suppression layer was applied before the sealant layer cured it was indicated as "before curing."

[0052] These test tires were evaluated for durability, sealing performance, ease of application of the gas permeation suppressing layer, and peel resistance of the gas permeation suppressing layer using the following test methods. The results are shown in Tables 1 and 2.

[0053] Durability: Each test tire was mounted on a wheel with a rim size of 21 x 9.0J and attached to a drum testing machine, and the tire was measured for running distance until the tire broke due to edge separation of the belt layer while periodically varying the load and slip angle at an air pressure of 120 kPa, a speed of 60 km / h, a load of 100% ± 25% of the maximum load capacity, and a slip angle of ± 5°. The evaluation results were expressed as an index, with the conventional example being 100. A higher index value indicates better durability. Sealability: Each test tire was mounted on a wheel with a rim size of 21 x 9.0J and the initial air pressure was set to 250 kPa. A nail with a diameter of 4.0 mm was driven into the tread in an environment of 23°C, and the nail was then removed and the tire was left for one hour, after which the air pressure was measured again. The evaluation results were expressed as an index, with the conventional example being 100. The higher the index value, the better the sealing performance.

[0054] Ease of application of gas permeation control layer: For each test tire, the work time required per tire to attach the gas permeation suppressing layer to the sealant layer was measured. The evaluation results were expressed as an index using the reciprocal of the measured value, with Example 1 being set at 100. A larger index value indicates better workability in attaching the gas permeation suppressing layer.

[0055] Peeling resistance of gas permeation control layer: After the durability test, the inner surface of each test tire was checked for peeling of the gas permeation suppressing layer. The evaluation results were indicated as follows: no peeling of the gas permeation suppressing layer at all was indicated by "◎", peeling over less than 1 / 8 of the total width of the gas permeation suppressing layer was indicated by "◯", peeling over less than 1 / 4 of the total width of the gas permeation suppressing layer was indicated by "△", and peeling over 1 / 4 or more of the total width of the gas permeation suppressing layer was indicated by "×".

[0056] [Table 1]

[0057] [Table 2]

[0058] As can be seen from Tables 1 and 2, in comparison with the conventional example and comparative example, the tires of Examples 1 to 23 had a gas permeation suppressing layer laminated on the radially inner side of the sealant layer, which made it possible to suppress deterioration of the belt layer due to oxygen that had permeated through the inner liner layer, and as a result, improved durability was observed. Furthermore, Examples 1 to 23 also had good sealing properties, ease of application of the gas permeation suppressing layer, and peel resistance of the gas permeation suppressing layer.

[0059] The present disclosure includes the following inventions [1] to

[15] . Invention [1] is a pneumatic tire comprising a tread portion extending in the tire circumferential direction and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the tire radially inward side of the sidewall portions, a carcass layer mounted between the pair of bead portions, a belt layer disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer disposed along the carcass layer, The pneumatic tire is characterized in that a sealant layer is formed on the inner surface of the tire in the tread portion, the sealant in the sealant layer is made of a silicone-based composition, and a gas permeation suppressing layer is laminated on the radially inner side of the sealant layer. Invention [2] is the pneumatic tire according to invention [1], characterized in that the oxygen permeability of the gas permeation suppression layer is lower than the oxygen permeability of the inner liner layer. Invention [3] is a gas permeation suppression layer having an oxygen permeability of 12 × 10 -10 cc·cm / cm 2 The pneumatic tire according to the invention [1] or [2] is characterized in that the tensile strength is 1.0 sq mHg or less. Invention [4] is the pneumatic tire according to any one of inventions [1] to [3], characterized in that the gas permeation suppression layer is a resin film. Invention [5] is a pneumatic tire according to any one of inventions [1] to [4], characterized in that the width of the gas permeation suppression layer is in the range of 80% to 120% of the width of the sealant layer. Invention [6] is a pneumatic tire according to any one of inventions [1] to [5], characterized in that the thickness of the gas permeation suppression layer is uniform along the tire width direction and is in the range of 5 μm to 500 μm. Invention [7] is a pneumatic tire according to any one of inventions [1] to [6], characterized in that the thickness of the inner liner layer at the portion overlapping with the gas permeation suppression layer is smaller than the thickness of the other portion. Invention [8] is the pneumatic tire according to any one of inventions [1] to [7], characterized in that an adhesive layer is interposed between the gas permeation suppression layer and the sealant layer. Invention [9] is a pneumatic tire according to any one of inventions [1] to [8], characterized in that the width of the sealant layer is 90% or more of the width of the belt layer located at the innermost side in the tire radial direction. Invention

[10] is the pneumatic tire according to any one of inventions [1] to [9], characterized in that the thickness of the sealant layer is in the range of 2.0 mm to 5.0 mm. An invention

[11] is the pneumatic tire according to any one of inventions [1] to

[10] , characterized in that the tan δ at 100° C. of the sealant layer is in the range of 0.2 to 0.6. An invention

[12] is the pneumatic tire according to any one of inventions [1] to

[11] , characterized in that the silicone composition is a two-component curing silicone. Invention

[13] is a method for manufacturing a pneumatic tire according to any one of Inventions [1] to

[12] , After manufacturing a pneumatic tire excluding the sealant layer and the gas permeation suppressing layer, A method for manufacturing a pneumatic tire, comprising: applying a sealant made of a silicone-based composition to the inner surface of the tire in the tread portion to form the sealant layer; and attaching the gas permeation suppressing layer to the inner surface of the sealant layer in the tire radial direction. Invention

[14] is the method for manufacturing a pneumatic tire according to Invention

[13] , characterized in that when a sealant made of a silicone-based composition is applied to the inner surface of the tire in the tread portion to form the sealant layer, the temperature of the sealant applied to the inner surface of the tire is lowered to below 70°C. Invention

[15] is a method for manufacturing a pneumatic tire according to invention

[13] or

[14] , characterized in that the gas permeation suppression layer is attached to the sealant layer before the sealant layer hardens. [Explanation of symbols]

[0060] 1 Tread section 2 Sidewall 3 Bead section 4 carcass layers 5 bead core 6 Bead filler 7 Belt Layer 8 Belt cover layer 9 Inner liner layer 10 Tire inner surface 20 Sealant Layer 21 Sealant Strip 25 Gas permeation suppression layer 26 Adhesive layer

Claims

1. A pneumatic tire comprising a tread portion extending in the tire circumferential direction and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed radially inward of the sidewall portions, a carcass layer mounted between the pair of bead portions, a belt layer disposed on the outer peripheral side of the carcass layer in the tread portion, and an inner liner layer disposed along the carcass layer, a sealant layer is formed on the tire inner surface in the tread portion, the sealant in the sealant layer is made of a silicone-based composition, and a gas permeation suppressing layer is laminated on the tire radially inward side of the sealant layer.

2. 2. The pneumatic tire according to claim 1, wherein the gas permeation suppression layer has an oxygen permeability lower than that of the inner liner layer.

3. The oxygen permeability of the gas permeation suppressing layer is 12×10 -10 cc・cm / cm 2 3. The pneumatic tire according to claim 1, wherein the pressure is 0.05 sec.cmHg or less.

4. 3. The pneumatic tire according to claim 1, wherein the gas permeation suppression layer is a resin film.

5. 3. The pneumatic tire according to claim 1, wherein the width of the gas permeation suppression layer is in the range of 80% to 120% of the width of the sealant layer.

6. 3. The pneumatic tire according to claim 1, wherein the gas permeation suppression layer has a uniform thickness in the tire width direction, in the range of 5 μm to 500 μm.

7. 3. The pneumatic tire according to claim 1, wherein the thickness of the inner liner layer at a portion overlapping the gas permeation suppressing layer is smaller than the thickness of the remaining portion.

8. 3. The pneumatic tire according to claim 1, wherein an adhesive layer is interposed between the gas permeation suppression layer and the sealant layer.

9. 3. The pneumatic tire according to claim 1, wherein the width of the sealant layer is 90% or more of the width of the belt layer located at the innermost position in the tire radial direction.

10. 3. The pneumatic tire according to claim 1, wherein the sealant layer has a thickness in the range of 2.0 mm to 5.0 mm.

11. 3. The pneumatic tire according to claim 1, wherein the sealant layer has a tan δ at 100° C. in the range of 0.2 to 0.

6.

12. 3. The pneumatic tire according to claim 1, wherein the silicone-based composition is a two-component curing silicone.

13. A method for manufacturing the pneumatic tire according to claim 1 or 2, After manufacturing a pneumatic tire excluding the sealant layer and the gas permeation suppressing layer, a sealant layer formed by applying a sealant made of a silicone-based composition to an inner surface of the tire in the tread portion, and attaching the gas permeation suppressing layer to the inner surface of the tire in the radial direction of the tire.

14. 14. The method for manufacturing a pneumatic tire according to claim 13, wherein when a sealant made of a silicone-based composition is applied to the tire inner surface in the tread portion to form the sealant layer, the temperature of the sealant applied to the tire inner surface is lowered to less than 70°C.

15. The method for manufacturing a pneumatic tire according to claim 13, wherein the gas permeation suppression layer is attached to the sealant layer before the sealant layer is cured.

Images