Manufacturing method for self-sealing tires

Abstract

This invention provides a method for manufacturing a self-sealing tire that suppresses the formation of gaps in the sealant layer and enables excellent sealing performance. [Solution] In a method for manufacturing a self-sealing tire comprising a tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3, and having a sealant layer 20 on the inner surface 10 of the tire in the tread portion 1, after manufacturing the tire excluding the sealant layer 20, the sealant layer 20 is formed by applying a strip of sealant material 21, which has an extruded shape that is substantially rectangular, in a spiral manner along the circumferential direction of the tire to the inner surface 10 of the tire in the tread portion 1, and the upper surface 23 and lower surface 22 of adjacent circumferential portions of the strip material 21 in the tire width direction are partially overlapped when applying the sealant.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a self-sealing tire having a sealant layer on the inner surface of the tire in the tread portion, and more particularly to a method for manufacturing a self-sealing tire that suppresses the formation of gaps in the sealant layer and enables excellent sealing performance to be exhibited.

Background Art

[0002] In a pneumatic tire, it has been proposed to provide a sealant layer on the inner side in the tire radial direction of the inner liner layer in the tread portion. In such a pneumatic tire, when a foreign object such as a nail pierces the tread portion, the sealant flows into the through-hole, thereby suppressing a decrease in air pressure and enabling driving to be maintained.

[0003] Conventionally, the sealant constituting the sealant layer is generally a rubber composition mainly composed of butyl rubber (see, for example, Patent Documents 1 to 3). Examples of butyl rubber include halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (Cl-IIR) in addition to butyl rubber (IIR). Such a sealant is applied to the inner surface of the tire in a state of being softened by heating to a high temperature (see, for example, Patent Document 4). More specifically, a sealant layer is formed by arranging a strip material of the sealant in a softened state by heating to a high temperature in a spiral shape along the tire circumferential direction on the inner surface of the tire.

[0004] However, when forming the sealant layer as described above, since the sealant is applied so that the circumferential portions of the sealant strip material are arranged in the tire width direction, a slight gap may be formed between the circumferential portions of the sealant strip material, and there is a problem that the sealing performance locally decreases at the site where such a gap occurs.

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 [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a method for manufacturing a self-sealing tire that suppresses the formation of gaps in the sealant layer and enables excellent sealing performance. [Means for solving the problem]

[0007] A method for manufacturing a self-sealing tire according to the present invention to achieve the above objective comprises a tread portion extending in the circumferential direction of the tire and forming an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of these sidewall portions, wherein the self-sealing tire has a sealant layer on the inner surface of the tire in the tread portion, After manufacturing the tire excluding the sealant layer, The sealant layer is formed on the inner surface of the tire in the tread portion by applying a strip of sealant material, which has an extruded shape that is approximately square, in a spiral pattern along the circumferential direction of the tire. This method is characterized by partially overlapping the upper and lower surfaces of adjacent circumferential portions of the strip material in the tire width direction when applying the sealant. [Effects of the Invention]

[0008] In this invention, when forming a sealant layer on the inner surface of the tire in the tread portion by applying a strip of sealant material, which has an extruded shape that is approximately square, in a spiral manner along the circumferential direction of the tire, the formation of gaps in the sealant layer is suppressed and excellent sealing performance is achieved by partially overlapping the upper and lower surfaces of adjacent circumferential portions of the strip material in the tire width direction.

[0009] In the present invention, it is preferable that the viscosity of the sealant at 30°C is 3000 Pa·s or less. By having a viscosity of 3000 Pa·s or less at 30°C, when the peripheral portions of the sealant strip material are partially overlapped, the sealant layer can be flattened by the weight of the sealant, and the formation of cavities within the sealant layer can be effectively prevented.

[0010] In this invention, it is preferable that the thixoindex of the sealant at 30°C is in the range of 1 to 5. When the thixoindex of the sealant at 30°C is 5 or less, when the peripheral portions of the sealant strip material are partially overlapped, the sealant layer is more likely to flatten due to the weight of the sealant, and the formation of voids within the sealant layer can be effectively prevented. Furthermore, when the thixoindex of the sealant at 30°C is 1 or more, the flow of the sealant is suppressed, so the sealant application speed can be increased and tire productivity can be improved.

[0011] In this invention, it is preferable that the width W of the sealant strip material and the overlap width w of the sealant strip material satisfy the relationship 1 / 3 ≤ w / W ≤ 2 / 3. A ratio w / W of 1 / 3 or more ensures that the peripheral portions of the sealant strip material can be reliably overlapped. Furthermore, a ratio w / W of 2 / 3 or less increases tire production efficiency.

[0012] In the present invention, it is preferable that the tire rotation speed when applying the sealant is in the range of 5 rpm to 30 rpm. When the tire rotation speed when applying the sealant is 5 rpm or higher, the centrifugal force during tire rotation makes it easier for the sealant layer to flatten, and the formation of voids within the sealant layer can be effectively prevented. Furthermore, when the tire rotation speed when applying the sealant is 30 rpm or lower, deterioration of uniformity due to uneven distribution of the sealant layer can be avoided.

[0013] In the present invention, it is preferable that the sealant is composed of a silicone-based composition. A sealant made of a silicone-based composition can exhibit excellent puncture sealing properties. Furthermore, a sealant made of a silicone-based composition has the advantage of excellent weather resistance and low temperature dependence of its physical properties. In particular, it is preferable that the silicone-based composition is a two-component curing silicone or a moisture-curing silicone. Two-component curing silicones and moisture-curing silicones have low viscosity during application, making it less likely for gaps to form in the sealant layer, while also having good flow resistance because they cure after application.

[0014] In the present invention, it is preferable that the surface curing time of the sealant is 1 hour or more and 12 hours or less. A surface curing time of 1 hour or more makes handling easier during production. Furthermore, a surface curing time of 12 hours or less prevents the sealant layer from crumbling during tire storage after sealant application.

[0015] In the present invention, it is preferable to attach the sound-absorbing material to the sealant layer after applying the sealant but before the sealant surface hardens. By attaching the sound-absorbing material to the sealant layer before the sealant surface hardens, good adhesion to the sound-absorbing material can be obtained when the sealant has hardened.

[0016] In the present invention, the viscosity of the sealant at 30°C is measured using a rotational viscometer in accordance with JIS-Z8803 under the condition of a rotational speed of 10 rpm. Further, the thixotropic index (TI) of the sealant at 30°C is the ratio of the viscosity (V 10 ) at 1 rpm to the viscosity (V1) at 10 rpm (TI = V1 / V 10 ). The thixotropic index is the gradient of the viscosity with respect to the rotational speed of the viscometer, and a higher thixotropic index means a less sagging property.

Brief Description of the Drawings

[0017] [Figure 1] It is a meridian cross-sectional view showing a self-sealing tire according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view showing a manufacturing method of the self-sealing tire of FIG. 1. [Figure 3] It is a plan view showing a sealant layer formed on the inner surface of the tire in the tread portion of the self-sealing tire of FIG. 1. [Figure 4] (a) to (c) are each a cross-sectional view showing an example of a sealant strip. [Figure 5] It is a cross-sectional view showing the state at the time of applying the sealant strip in the present invention. [Figure 6] It is a cross-sectional view showing a state in which a gap is formed between the circumferential portions of the sealant strip. [Figure 7] It is a cross-sectional view showing a state in which a cavity is formed in the sealant layer. [Figure 8] It is a meridian cross-sectional view showing a self-sealing tire according to another embodiment of the present invention.

Modes for Carrying Out the Invention

[0018] Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a self-sealing tire according to an embodiment of the present invention.

[0019] As shown in Figure 1, the self-sealing tire of this embodiment comprises a tread portion 1 that extends in the circumferential direction of the tire and forms an annular 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 these sidewall portions 2.

[0020] A carcass layer 4 is mounted between a pair of bead sections 3, 3. This carcass layer 4 includes multiple carcass cords extending in the radial direction of the tire, which are folded back from the inside to the outside of the tire around the bead core 5 located in each bead section 3. A bead filler 6 made of a rubber composition with a triangular cross-section is placed on the outer circumference of the bead core 5.

[0021] On the other hand, multiple belt layers 7 are embedded on the outer circumference 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 the belt cords are arranged so as to intersect each other between 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 outside the first belt layer 7A, with the width of the first belt layer 7A being 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 to, for example, a range of 10° to 40°. Steel cords are preferably used as the belt cords of the belt layers 7.

[0022] On the outer circumference of the belt layer 7, at least one belt cover layer 8 is arranged, with reinforcing cords arranged at an angle of, for example, 5° or less with respect to the tire circumferential direction, for the purpose of improving high-speed durability. It is desirable that this belt cover layer 8 has a jointless structure in which a strip material made of at least one reinforcing cord aligned and covered with rubber is continuously wound at substantially 0° with respect to the tire circumferential direction. Organic fiber cords such as nylon or polyethylene terephthalate (PET) are preferably used as the reinforcing cords of the belt cover layer 8.

[0023] The tire internal structure described above is a typical example for pneumatic tires, but is not limited to this. The tread portion 1 has various grooves formed in it, including multiple main grooves 11 that extend in the circumferential direction of the tire.

[0024] In the above-described pneumatic tire, a sealant layer 20 is formed on the inner surface 10 of the tire in the tread portion 1 so as to be continuous in the circumferential direction of the tire. Preferably, the center position of the sealant layer 20 in the tire width direction coincides with the tire equator, but the center position may be offset from the tire equator toward 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 is preferably 10 mm or less, more preferably 5 mm or less. This ensures that the sealant layer 20 does not adversely affect the tire balance. The sealant of the sealant layer 20 may be composed of a rubber composition mainly composed of butyl rubber, but is preferably composed of a silicone-based composition. The silicone-based composition includes synthetic polymer compounds having a main skeleton of siloxane bonds.

[0025] The pneumatic tire described above can be manufactured by the following method. First, a pneumatic tire is manufactured as described above, comprising a tread portion 1, a pair of sidewall portions 2, and a pair of bead portions 3. Next, a sealant made of, for example, a silicone-based composition is applied to the inner surface 10 of the tire in the tread portion 1 to form a sealant layer 20.

[0026] Figure 2 shows a specific manufacturing method for the pneumatic tire shown in Figure 1, and Figure 3 shows the sealant layer formed on the inner surface of the tire in the tread area. In Figure 2, the sealant extruder 31 mixes the sealant supplied from pumps 32 and 33 and continuously discharges the mixed sealant as a strip material 21 from a nozzle 34. The nozzle 34 of this sealant extruder 31 is configured to be freely displaceable. Therefore, by moving the nozzle 34 in the axial direction of the tire while rotating the tire, starting from a state where the nozzle 34 is close to the inner surface 10 of the tire, the sealant strip material 21 can be arranged spirally on the inner surface 10 of the tire while being inclined with respect to the circumferential direction Tc of the tire (see Figure 3). The circumferential portions of the spirally arranged sealant strip material 21 are in close contact with each other. The spirally arranged sealant strip material 21 thus integrate to form a sealant layer 20.

[0027] Figures 4(a) to 4(c) show cross-sections of the sealant strip material 21, respectively. As shown in Figures 4(a) to 4(c), the strip material 21 has an extruded shape that is approximately rectangular. More specifically, the strip material 21 has a flat lower surface 22 that abuts against the inner surface 10 of the tire, an upper surface 23 opposite to the lower surface 22, and a pair of side surfaces 24 and 25 that connect the lower surface 22 and the upper surface 2 to each other. The extruded shape of the strip material 21 is preferably a rectangle as shown in Figure 4(a), but it may also be a rectangle with a smoothly bulging upper surface 23 as shown in Figure 4(b), or a trapezoid as shown in Figure 4(c).

[0028] Figure 5 shows the state of the sealant strip material 21 during application according to the present invention. As shown in Figure 5, when forming a sealant layer 20 by applying a sealant strip material 21, which has an extruded shape that is approximately rectangular, in a spiral manner along the circumferential direction of the tire to the inner surface 10 of the tread portion 1, the upper surface 23 and lower surface 22 of adjacent circumferential portions of the strip material 21 in the tire width direction are partially overlapped. As a result, the sealant layer 20 levels due to the weight of the sealant itself, making it possible to apply the sealant without gaps and to exhibit excellent sealing performance. However, as shown in Figure 6, if the sealant strip material 21 is placed without overlapping, gaps may be formed between the circumferential portions. In this case, the sealing performance will be locally reduced in the areas where gaps are formed.

[0029] In the manufacturing method described above, the viscosity of the sealant at 30°C should be 3000 Pa·s or less. By having a viscosity of 3000 Pa·s or less at 30°C, when the peripheral portions of the sealant strip material 21 are partially overlapped, the sealant layer 20 flattens due to the weight of the sealant, effectively preventing the formation of voids within the sealant layer 20. Conversely, if the viscosity of the sealant at 30°C is greater than 3000 Pa·s, the leveling of the sealant layer 20 becomes insufficient, and voids may form within the sealant layer 20, as shown in Figure 7. Furthermore, from the viewpoint of suppressing sealant flow, the lower limit of the viscosity of the sealant at 30°C is preferably 1000 Pa·s. Also, the temperature during sealant application should be, for example, in the range of 30°C to 40°C, preferably in the range of 25°C to 35°C.

[0030] In the manufacturing method described above, it is desirable for the sealant's thixoindex at 30°C to be in the range of 1 to 5. A thixoindex of 5 or less at 30°C allows the sealant layer 20 to flatten more easily due to the sealant's own weight when the peripheral portions of the sealant strip material 21 are partially overlapped, effectively preventing the formation of voids within the sealant layer 20. Conversely, if the sealant's thixoindex at 30°C is greater than 5, the sealant layer 20 becomes difficult to level, potentially leading to the formation of voids within the sealant layer 20. Furthermore, a thixoindex of 1 or greater at 30°C suppresses sealant flow, allowing for a faster sealant application speed and increased tire productivity. Conversely, if the sealant's thixoindex at 30°C is less than 1, the sealant flows more easily, requiring a slower application speed and thus reducing tire productivity.

[0031] In the manufacturing method described above, as shown in Figure 5, it is desirable that the width W of the sealant strip material 21 and the overlap width w of the sealant strip material 21 satisfy the relationship 1 / 3 ≤ w / W ≤ 2 / 3. When the ratio w / W is 1 / 3 or greater, the peripheral portions of the sealant strip material 21 can be reliably overlapped. Conversely, if the ratio w / W is less than 1 / 3, there is a risk that the peripheral portions of the sealant strip material 21 will not overlap, for example, when the unevenness of the inner surface 10 of the tire is large. Also, when the ratio w / W is 2 / 3 or less, the productivity of tire production can be increased. Conversely, if the ratio w / W is greater than 2 / 3, it will take longer to apply the sealant, and the productivity of tire production will decrease.

[0032] In the manufacturing method described above, the tire rotation speed when applying the sealant is preferably in the range of 5 rpm to 30 rpm. When the tire rotation speed when applying the sealant is 5 rpm or higher, the centrifugal force during tire rotation makes it easier for the sealant layer 20 to flatten, effectively preventing the formation of cavities within the sealant layer 20. Conversely, if the tire rotation speed when applying the sealant is lower than 5 rpm, there is a risk of cavities forming within the sealant layer 20 due to insufficient centrifugal force. Also, when the tire rotation speed when applying the sealant is 30 rpm or lower, deterioration of uniformity due to uneven distribution of the sealant layer 20 can be avoided. Conversely, if the tire rotation speed when applying the sealant is higher than 30 rpm, the sealant tends to shift towards the center in the width direction of the tire, which may worsen uniformity.

[0033] In the manufacturing method described above, it is preferable that the sealant be composed of a silicone-based composition. A sealant layer 20 is formed on the inner surface 10 of the tire in the tread portion 1, having a structure in which sealant strips 21 are arranged spirally along the circumferential direction of the tire. Since the sealant is composed of a silicone-based composition, the circumferential portions of the sealant strips 21 become more easily integrated with each other during the curing reaction process of the silicone-based composition, resulting in good integration between the circumferential portions of the sealant strips 21, thus improving the sealing performance of the sealant layer 20. Furthermore, because the circumferential portions of the sealant strips 21 are well integrated, the sealant layer 20 is less likely to flow towards the center in the width direction of the tire due to the centrifugal force generated when the tire rotates, which also contributes to the improvement of sealing performance. In addition, when a silicone-based composition is used as the sealant for the sealant layer 20, it has the advantage of excellent weather resistance and low temperature dependence of its physical properties.

[0034] As the silicone-based composition constituting the sealant in the sealant layer 20, one-component curing silicone or two-component curing silicone can be used. An example of a one-component curing silicone is a moisture-curing silicone. Two-component curing silicones or moisture-curing silicones have low viscosity during application, making it less likely for gaps to form in the sealant layer 20, while also having good flow resistance because they cure after application. Two-component curing silicones consist of a first liquid and a second liquid. The curing reaction begins when these first and second liquids are mixed, and stability as a sealant layer 20 is ensured after curing. In the apparatus described above, the first and second liquids of the two-component curing silicone are supplied from pumps 32 and 33, respectively. Examples of two-component curing silicones include those described in Japanese Patent Publication No. 2018-503725 and Japanese Patent Publication No. 2022-550962. As a commercially available two-component curing silicone, for example, Dow's SST-2650 can be used.

[0035] Two-component curing silicones are composed of, for example, condensation-curable silyl-terminated polymers, silane crosslinking agents, condensation catalysts, and fillers. Examples of condensation-curable silyl-terminated polymers include polydialkylsiloxanes, alkylphenylsiloxanes, organic polymers having silyl groups (e.g., silyl polyethers, silyl acrylates), and polyisobutylene having silyl groups. Examples of silane crosslinking agents include alkoxy-functional silanes, oxymosilanes, acetoxysilanes, and enoxysilanes. Examples of fillers include iron oxides, titanium dioxide, carbon black, and talc. Examples of condensation catalysts include titanate and zirconate. These condensation-curable silyl-terminated polymers, silane crosslinking agents, condensation catalysts, and fillers are stored in a state where the curing reaction does not proceed in combination as a first liquid and a second liquid, and are mixed at the time of use.

[0036] In the manufacturing method described above, it is preferable that the surface hardening time of the sealant be between 1 hour and 12 hours. A surface hardening time of 1 hour or more makes handling easier during production. Conversely, if the surface hardening time of the sealant is less than 1 hour, the hardening speed is too fast, making handling difficult during production. Also, a surface hardening time of 12 hours or less prevents the sealant layer 20 from collapsing during tire storage after sealant application. Conversely, if the surface hardening time of the sealant is more than 12 hours, the hardening speed is too slow, and there is a risk that the sealant layer 20 will collapse during tire storage after sealant application. Surface hardening time is the time until the viscosity (tack) of the surface disappears. Surface hardening time is measured by the fingertip method. The fingertip method is a method in which an unhardened sample is placed flat on a glass plate, the surface is touched with a fingertip cleaned with ethyl alcohol, and this is repeated in different locations, and the time until the sample no longer adheres to the fingertip is measured.

[0037] Figure 8 shows a self-sealing tire according to another embodiment of the present invention. In Figure 8, a sound-absorbing material 40 is installed along the circumferential direction of the tire on the radially inner side of the sealant layer 20. The sound-absorbing material 40 is composed of a porous material having open cells and has predetermined sound-absorbing properties based on its porous structure. Foamed polyurethane is preferably used as the porous material for the sound-absorbing material 40.

[0038] When manufacturing such self-sealing tires, the sound-absorbing material 40 is attached to the sealant layer 20 after the sealant has been applied but before the sealant has hardened. This allows for good adhesion between the sound-absorbing material 40 and the hardened sealant. In this case, the sound-absorbing effect based on the sound-absorbing material 40 can be obtained while preventing foreign matter from adhering to the sealant layer 20. In particular, if the sealant of the sealant layer 20 is made of a silicone-based composition, the sound-absorbing material 40 is installed on the sealant layer 20 which has been applied at a low temperature, thus avoiding damage to the sound-absorbing material 40 and maintaining its sound-absorbing effect well. [Examples]

[0039] In manufacturing a self-sealing tire with a tire size of 255 / 45R19, comprising a tread section, a pair of sidewall sections, and a pair of bead sections, and having a sealant layer on the inner surface of the tire in the tread section, the sealant layer was formed by applying a sealant strip material with an extruded shape that is approximately square in a spiral pattern along the circumferential direction of the tire to the inner surface of the tire in the tread section. Comparative Examples 1 and Examples 1 to 23 were manufactured by varying the presence or absence of overlap of the sealant strip material during application, the viscosity of the sealant at 30°C, the thixoindex of the sealant at 30°C, the ratio of the width W of the sealant strip material to the overlap width w of the sealant strip material w / W, the tire rotation speed when applying the sealant, the type of sealant, and the surface curing time of the sealant, as shown in Tables 1 and 2. The types of sealants used were two-component curing silicone (A), moisture-curing silicone (B), or butyl rubber (C).

[0040] For these test tires, the presence or absence of gaps, uniformity, sealant application time, and flow resistance were evaluated using the test methods described below, and the results are shown in Tables 1 and 2.

[0041] Presence or absence of gaps: For each test tire, the presence or absence of gaps (including voids) in the sealant layer was checked. If gaps were present, the gap area was measured, and the ratio of that gap area to the coated area was calculated. The evaluation results were indicated as follows: "○" for no gaps, "△" for gaps present (gap area ratio less than 5%), and "×" for gaps present (gap area ratio 5% or more).

[0042] Uniformity: For each test tire, the thickness of the sealant layer was measured at 40 locations, and the standard deviation was calculated. The evaluation results were expressed as an index using the reciprocal of the standard deviation, with Comparative Example 1 set to 100. A larger index value indicates better uniformity.

[0043] Sealant application time: For each test tire, the sealant application time was measured with a sealant application width of 200 mm. The target application time is 180 seconds or less.

[0044] Flow resistance: Each test tire was mounted on a wheel with a rim size of 19 x 8.5J and placed on an indoor drum testing machine (drum diameter 1707 mm). The air pressure was set to 230 kPa, the load to 100% of the maximum load capacity, and the speed was set to 200 km / h for a one-hour driving test. After the test, the degree of sealant flow was checked. The evaluation results were indicated as follows: "○" for no flow, "△" for some flow (less than 1 / 4 of the total), and "×" for some flow (1 / 4 or more of the total).

[0045] [Table 1]

[0046] [Table 2]

[0047] As can be seen from Tables 1 and 2, Examples 1 to 23 were able to suppress the formation of gaps in the sealant layer compared to Comparative Example 1, that is, a self-sealing tire with excellent sealing properties was obtained.

[0048] This disclosure encompasses the following inventions [1] to [9]. The invention [1] relates to a method for manufacturing a self-sealing tire comprising a tread portion extending in the circumferential direction of the tire and forming an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of the sidewall portions, wherein the tire has a sealant layer on the inner surface of the tread portion, After manufacturing the tire excluding the sealant layer, The sealant layer is formed on the inner surface of the tire in the tread portion by applying a strip of sealant material, which has an extruded shape that is approximately square, in a spiral pattern along the circumferential direction of the tire. This is a method for manufacturing a self-sealing tire, characterized by partially overlapping the upper and lower surfaces of adjacent circumferential portions of the strip material in the tire width direction when applying the sealant. Invention [2] is a method for manufacturing a self-sealing tire according to Invention [1], characterized in that the viscosity of the sealant at 30°C is 3000 Pa·s or less. Invention [3] is a method for manufacturing a self-sealing tire according to Invention [1] or [2], characterized in that the thixoindex of the sealant at 30°C is in the range of 1 to 5. Invention [4] is a method for manufacturing a self-sealing tire according to any one of Inventions [1] to [3], characterized in that the width W of the sealant strip material and the overlap width w of the sealant strip material satisfy the relationship 1 / 3 ≤ w / W ≤ 2 / 3. Invention [5] is a method for manufacturing a self-sealing tire according to any one of Inventions [1] to [4], characterized in that the tire rotation speed when applying the sealant is in the range of 5 rpm to 30 rpm. Invention [6] is a method for manufacturing a self-sealing tire according to any one of Inventions [1] to [5], characterized in that the sealant is composed of a silicone-based composition. Invention [7] is a method for manufacturing a self-sealing tire according to Invention [6], characterized in that the silicone composition is a two-component curing silicone or a moisture-curing silicone. Invention [8] is a method for manufacturing a self-sealing tire according to any one of Inventions [1] to [7], characterized in that the surface hardening time of the sealant is 1 hour or more and 12 hours or less. Invention [9] is a method for manufacturing a self-sealing tire according to any one of Inventions [1] to [8], characterized in that a sound-absorbing material is attached to the sealant layer after the application of the sealant but before the surface hardening of the sealant. [Explanation of Symbols]

[0049] 1. Tread section 2 Sidewall section 3. Bead section 4. Carcass layer 5 Bead core 6. Bead Filler 7 Belt layer 8 Belt cover layer 10. Inside of the tire 20 sealant layer 21. Sealant strip 22 Bottom side 23 Top side 24,25 Side view 31. Sealant extruder 40 Sound-absorbing materials

Claims

1. A method for manufacturing a self-sealing tire comprising a tread portion extending in the circumferential direction of the tire and forming an annular shape, a pair of sidewall portions arranged on both sides of the tread portion, and a pair of bead portions arranged radially inward of these sidewall portions, wherein the tire has a sealant layer on the inner surface of the tread portion, After manufacturing the tire excluding the sealant layer, The sealant layer is formed on the inner surface of the tire in the tread portion by applying a strip of sealant material, which has an extruded shape that is approximately square, in a spiral pattern along the circumferential direction of the tire. A method for manufacturing a self-sealing tire, characterized by partially overlapping the upper and lower surfaces of adjacent circumferential portions of the strip material in the tire width direction when applying the sealant.

2. The method for manufacturing a self-sealing tire according to claim 1, characterized in that the viscosity of the sealant at 30°C is 3000 Pa·s or less.

3. The method for manufacturing a self-sealing tire according to claim 1 or 2, characterized in that the thixoindex of the sealant at 30°C is in the range of 1 to 5.

4. The method for manufacturing a self-sealing tire according to claim 1 or 2, characterized in that the width W of the sealant strip material and the overlap width w of the sealant strip material satisfy the relationship 1 / 3 ≤ w / W ≤ 2 / 3.

5. The method for manufacturing a self-sealing tire according to claim 1 or 2, characterized in that the tire rotation speed when applying the sealant is in the range of 5 rpm to 30 rpm.

6. The method for manufacturing a self-sealing tire according to claim 1 or 2, characterized in that the sealant is composed of a silicone-based composition.

7. The method for manufacturing a self-sealing tire according to claim 6, characterized in that the silicone composition is a two-component curable silicone or a moisture-curable silicone.

8. The method for manufacturing a self-sealing tire according to claim 1 or 2, characterized in that the surface curing time of the sealant is 1 hour or more and 12 hours or less.

9. A method for manufacturing a self-sealing tire according to claim 1 or 2, characterized in that after applying the sealant and before the surface hardening of the sealant, a sound-absorbing material is attached to the sealant layer.

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