Pneumatic tires and methods for manufacturing them

Abstract

A pneumatic tire capable of satisfactorily maintaining its sealing properties through a sealant layer and a method for manufacturing the pneumatic tire are provided. The pneumatic tire includes a tread section (1) extending in a circumferential direction and having a ring shape, a pair of sidewall sections (2) arranged on both sides of the tread section (1), and a pair of bead sections (3) arranged on an inner surface of the sidewall sections (2) in a radial direction of the tire, wherein a sealant layer (20) having a structure in which a strip (21) of a sealant is arranged spirally along the circumferential direction of the tire is formed on an inner surface (10) of the tire in the tread section (1), and the sealant consists of a silicone-based composition.

Description

Technical field

[0001] The present invention relates to a pneumatic tire including a sealing layer on an inner tire surface in a tread section and a method for manufacturing therefor, and relates in particular to a pneumatic tire which can satisfactorily maintain the sealing properties through the sealing layer, and a method for manufacturing therefor. State of the art

[0002] In a proposed pneumatic tire, a sealant layer is provided on the inner surface of an inner liner layer in a section of the tread, running radially in the direction of the tire's radial axis. If a foreign object, such as a nail, penetrates this section of the tread, sealant flows into a through-hole, thus preventing a drop in air pressure and allowing the journey to continue.

[0003] In the prior art, the sealant forming the sealant layer is typically a rubber composition consisting mainly of a butyl-based rubber (see, for example, patent documents 1 to 3). Examples of butyl-based rubber include not only butyl rubber (IIR) but also halogenated butyl rubbers such as brominated butyl rubber (Br-IIR) and chlorinated butyl rubber (CI-IIR). Such a sealant is applied to the inner surface of a tire in a state softened by heating to a high temperature (see, for example, patent document 4). More precisely, the sealant layer is formed by spirally arranging a strip of sealant, in a state softened by heating to a high temperature, on the inner surface of the tire along a circumferential direction.

[0004] In the sealant layer formed as described above, the sealant cools before the circumferential sections of the sealant strip bond together, resulting in unsatisfactory integrity of these sections and consequently, inadequate sealing properties. Furthermore, this insufficient integrity also causes the sealant layer to flow towards the center of the tread section due to centrifugal force generated during tire rotation, further reducing its sealing performance. List of literature on patent literature Patent document 1: JP 6583456 B Patent document 2: JP 6620851 B Patent Document 3: JP 7319533 B Patent Document 4: JP 6124967 B Brief description of the invention: Technical problem

[0005] One object of the present invention is to provide a pneumatic tire which can satisfactorily maintain the sealing properties by means of a sealing agent layer, and a method for manufacturing the pneumatic tire. Solution to the problem

[0006] A pneumatic tire according to the present invention for fulfilling the above-described problem is a pneumatic tire comprising a tread section extending in a tire circumferential direction and having a ring shape, a pair of sidewall sections arranged on both sides of the tread section, and a pair of bead sections arranged on an inner side of the sidewall sections in a tire radial direction, wherein a sealant layer having a structure in which a strip of a sealant is arranged spirally along the tire circumferential direction is formed on an inner surface of the tire in the tread section, and the sealant comprising a silicone-based composition.

[0007] A method for manufacturing a pneumatic tire according to the present invention to fulfill the above objective is a method for manufacturing the pneumatic tire described above, including: Manufacturing the pneumatic tire excluding the sealant layer, and forming the sealant layer by applying a sealant that includes a silicone-based composition to the inner surface of the tire in the tread section and adjusting the temperature of the sealant applied to the inner surface of the tire to less than 70 °C. Advantageous effects of the invention

[0008] In the present invention, a sealant layer, having a structure in which a strip of sealant is arranged spirally along the tire's circumferential direction, is formed on an inner tire surface in a tread section, and the sealant consists of a silicone-based composition, whereby circumferential sections of the sealant strip can be easily adapted to one another in a curing reaction process of the silicone-based composition and the integrity of the circumferential sections of the sealant strip is satisfactorily improved, so that the sealing properties can be improved by the sealant layer.Furthermore, since the integrity of the sealant strip's circumferential sections is good, the sealant layer is less likely to flow towards the center in the tire's width direction due to centrifugal force generated during tire rotation, which also contributes to improved sealing properties. Additionally, because the sealant, which consists of a silicone-based composition, can be applied at a low temperature, and the temperature of the sealant applied to the inner tire surface can be below 70°C, the advantage is that the heat impact on the tire is reduced, thus preventing a deterioration in tire performance.

[0009] In the present invention, the silicone-based composition is preferably a two-part curable silicone. Since the two-part curable silicone has a low viscosity immediately after the two parts are mixed, it can also be applied at low temperatures.

[0010] In the present invention, the sealant preferably has a glass transition temperature in the range of -120 °C to -40 °C. By using a sealant with a low glass transition temperature, the tire puncture sealing properties can be satisfactorily ensured in low-temperature environments.

[0011] In the present invention, the sealant layer preferably has a thickness in the range of 2.0 mm to 5.0 mm. This makes it possible to suppress a deterioration in rolling resistance due to an increase in tire weight and to suppress uneven distribution of the sealant layer due to the flow of the sealant, while at the same time ensuring the tire puncture sealing properties.

[0012] In the present invention, in a case where a belt layer including a belt cord thread inclined with respect to the tire's circumferential direction is embedded in the tread section, the inclination direction of the sealant strip with respect to the tire's circumferential direction is preferably opposite in phase to the inclination direction of a belt cord thread of a belt layer on an innermost side in a tire radial direction with respect to the tire's circumferential direction. In a pneumatic tire, crab tread occurs due to the orientation of the belt cord thread of the belt layer, and the orientation of the sealant strip also causes crab tread.Therefore, it is possible to reduce crab tread by causing the inclination direction of the sealant strip with respect to the tire circumferential direction to be opposite to the inclination direction of the belt cord thread of the belt layer on the innermost side in the tire radial direction with respect to the tire circumferential direction.

[0013] In the present invention, in a case where the belt layer, including the belt cord thread inclined to the tire circumference, is embedded in the tread section, the width of the sealant layer is preferably 90% or more of the width of the belt layer on the innermost side in the tire radial direction. In particular, an end section of the sealant layer is preferably positioned further on an outer side in the tire width direction than an end section of the belt layer on the innermost side in the tire radial direction. A sufficiently large width of the sealant layer effectively prevents a puncture in the pneumatic tire.

[0014] In the present invention, in a case where a belt cover layer, which encloses organic fiber cord threads oriented in the tire's circumferential direction on the outside of the belt layer, is embedded in the tread section, the end section of the sealant layer is preferably located further outwards in the tire width direction than an end section of the belt cover layer. A sufficiently large width of the sealant layer effectively prevents a puncture in the pneumatic tire.

[0015] In the present invention, the distance L between the belt layer and the sealant layer in all sections of the belt layer located on the innermost side in the tire radial direction is preferably 10 mm or less. This allows the sealant to easily flow into the belt layer if a foreign object such as a nail penetrates the tread section, thus ensuring good tire puncture sealing properties.

[0016] In the present invention, the ratio between the thickness S of the sealant layer and the distance L from the belt layer on the innermost side in the tire radial direction to the sealant layer preferably satisfies a relationship of S / L ≥ 0.3. By making the thickness S of the sealant layer sufficiently large in relation to the distance L, good tire puncture sealing properties can be ensured.

[0017] In the present invention, a sound-absorbing element is preferably arranged along the circumferential direction of the tire on an inner surface of the sealant layer in the radial direction of the tire. In this case, the sound-absorbing element can be arranged on the sealant layer applied at a low temperature, thereby preventing damage to the sound-absorbing element and ensuring its sound-absorbing effect is satisfactorily maintained. Brief description of the drawings Fig. Figure 1 is a meridian cross-sectional view illustrating a pneumatic tire according to an embodiment of the present invention. Fig. Figure 2 is a cross-sectional view showing a major part of the pneumatic tire. Fig. 1 illustrates. Fig. 3 is a top view showing a belt layer, a belt cover layer and a sealant layer as an extract of the pneumatic tire from Fig. 1 illustrates. Fig. Figure 4 is a cross-sectional view showing a method for manufacturing the pneumatic tire of Fig. 1 illustrates. Fig. 5 is a top view illustrating the sealant layer applied to the inner surface of a tire in a tread section of the pneumatic tire. Fig. 1 is trained. Fig.Figure 6 is a meridian cross-sectional view illustrating an air tire according to another embodiment of the present invention. Description of embodiments

[0018] One configuration of an embodiment of the present invention is described in detail below with reference to the accompanying drawings. Fig. 1, Fig. 2 to Fig. Figure 3 shows a pneumatic tire according to an embodiment of the present invention.

[0019] As in Fig. As illustrated in Figure 1, a pneumatic tire of the present invention includes a tread section 1 extending in the circumferential direction of the tire and having a ring shape, a pair of sidewall sections 2, 2 arranged on both sides of the tread section 1, and a pair of bead sections 3, 3 arranged on an inner side in the radial direction of the sidewall sections 2.

[0020] A carcass layer 4 is mounted between the pair of bead sections 3, 3. The carcass layer 4 encloses a plurality of carcass cord threads extending in the tire radial direction and is folded back from one tire inside to one tire outside around a bead core 5 located in each bead section 3. A bead filler 6, having a triangular cross-sectional shape and made of a rubber compound, is arranged on the outer circumference of the bead core 5.

[0021] On the other hand, a plurality of belt layers 7 are embedded on the outer circumferential side of the carcass layer 4 in the tread section 1. The belt layers 7 enclose a plurality of belt cord threads that are inclined with respect to the tire's circumferential direction and arranged such that the belt cord threads of the layers intersect each other. The inclination angle of the belt cord thread in the belt layers 7 with respect to the tire's circumferential direction is set within a range of, for example, 10° to 40°. Steel cord threads are preferably used as the belt cord threads of the belt layers 7.

[0022] To improve durability at high speeds, at least one belt cover layer 8, formed by arranging reinforcing cord threads, for example, at an angle of no more than 5° with respect to the tire's circumferential direction, is arranged on the outer circumferential side of the belt layers 7. The belt cover layer 8 preferably has a seamless structure in which a strip material, made of at least one reinforcing cord thread laid out and covered with rubber, is continuously wound at substantially an angle of 0° with respect to the tire's circumferential direction. Preferably, a cord thread made of an organic fiber such as nylon and polyethylene terephthalate (PET) is used as the reinforcing cord thread for the belt cover layer 8.

[0023] It should be noted that the tire internal structure described above is a typical example for pneumatic tires, but is not limited to them. A plurality of grooves, including a plurality of main grooves 11 extending in the circumferential direction of the tire, are formed in the tread section 1.

[0024] In the pneumatic tire described above, a sealant layer 20 is continuously formed in the circumferential direction on an inner tire surface 10 in the tread section 1. Preferably, the central position of the sealant layer 20 coincides with the tire equator in the tire width direction, but the central position in the tire width direction can also be offset to either side of the tire equator. A distance in the tire width direction between the central position of the sealant layer 20 and the tire equator is preferably 10 mm or less, more preferably 5 mm or less. Consequently, the sealant layer 20 does not impair the tire's equilibrium. As described in Fig.As illustrated in Figure 3, the sealant layer 20 has a structure in which a strip 21 of sealant is arranged spirally along the tire's circumferential direction. The sealant of the sealant layer 20 is composed of a silicone-based composition. The silicone-based composition includes a synthetic polymer compound with a main backbone formed by siloxane bonds.

[0025] The pneumatic tire described above can be manufactured using the following method. First, the pneumatic tire is manufactured, comprising the tread section 1, the two sidewall sections 2, and the two bead sections 3, as described above, with the belt layer 7 and the belt cover layer 8 embedded in the tread section 1. Next, the sealant layer 20 is formed by applying a sealant consisting of a silicone-based composition to the inner surface 10 of the tread section 1.

[0026] Fig. Figure 4 illustrates a specific process for manufacturing the pneumatic tire of Fig. 1 and Fig. Figure 5 illustrates the sealant layer that forms on the inner surface of the tire in the tread section. Fig.4. A sealant extrusion device 31 mixes the sealant supplied by pumps 32, 33 and continuously dispenses the mixed sealant as a strip 21 from a nozzle 34. The sealant extrusion device 31 is configured such that the position of the nozzle 34 can be freely moved. Therefore, by moving the nozzle 34 in a tire axial direction during tire rotation from a state in which the nozzle 34 is brought close to the inner tire surface 10, the strip 21 of sealant can be arranged spirally on the inner tire surface 10 while inclined with respect to a tire circumferential direction Tc (see Fig. 5) The spirally arranged strip 21 of sealant has circumferential sections in close contact with each other. The spirally arranged strip 21 of sealant is formed in one piece to form the sealant layer 20.

[0027] In the pneumatic tire described above, the sealant layer 20, which has a structure in which the strip 21 of the sealant is arranged spirally along the tire's circumferential direction, is formed on the inner surface 10 of the tire in the tread section 1, and the sealant consists of a silicone-based composition, so that the circumferential sections of the sealant strip 21 are easily adapted to one another in a curing reaction process of the silicone-based composition and the integrity of the circumferential sections of the sealant strip 21 is satisfactorily improved, thereby enabling an improvement in the sealing properties by the sealant layer 20.Since the integrity of the circumferential sections of the sealant strip 21 is good, the sealant layer 20 is also less likely to flow towards the center in the tire width direction due to the centrifugal force generated during tire rotation, which also contributes to improving the sealing properties. Furthermore, when the silicone-based composition is used as the sealant in the sealant layer 20, the advantages arise that it exhibits excellent weather resistance and low temperature dependence of its physical properties.

[0028] Since the silicone-based composition exhibits good flowability even at low temperatures, the temperature of the sealant applied to the inner surface of the tire 10 can be below 70 °C. This reduces the effect of heat on the tire and prevents a deterioration in tire performance. At temperatures of 70 °C or higher, the heat effect on the tire becomes significant and contributes to a decline in tire performance. In particular, the temperature of the sealant applied to the inner surface of the tire 10 is preferably 35 °C or less. Furthermore, considering the flowability of the silicone-based composition, the lower limit for the temperature of the sealant applied to the inner surface of the tire 10 can be 20 °C.

[0029] The silicone-based composition forming the sealant of the sealant layer 20 can be a one-part or a two-part curable silicone, with the two-part curable silicone being particularly preferred. Examples of the one-part curable silicone include a moisture-curable silicone. The two-part curable silicone comprises a first liquid and a second liquid, and the curing reaction is initiated by mixing the first and second liquids, thus ensuring the stability of the sealant layer 20 after curing. In the apparatus described above, the first and second liquids of the two-part curable silicone are supplied by pumps 32 and 33, respectively. Since the two-part curable silicone has a low viscosity immediately after the two parts are mixed, it can also be applied at low temperatures.In particular, the two-part curable silicone is preferably one in which the time until complete curing is five days or more.

[0030] The two-part curable silicone consists of, for example, a condensation-curable silyl-terminated polymer, a silane crosslinking agent, a condensation catalyst, a filler, and the like. Examples of condensation-curable polymers with a silyl-terminated polymer include polydialkylsiloxane, alkylphenylsiloxane, organic polymers containing a silyl group (e.g., silyl polyether, silyl acrylate), polyisobutylene containing a silyl group, and the like. Examples of the silane crosslinking agent include alkoxy-functional silanes, oximosilanes, acetoxysilanes, and enoxysilanes. Examples of the filler include iron oxide, titanium dioxide, carbon black, and talc. Examples of the condensation catalyst include titanates and zirconates.The condensation-curable silyl-terminated polymer, the silane crosslinking agent, the condensation catalyst, and the filler are stored in a state where they are separated into a first liquid and a second liquid in a combination in which no curing reaction occurs, and are mixed upon use. Examples of two-part curable silicone include those described in JP 2018-503725 A and JP 2022-550962 A. For example, SST-2650, available from Dow Inc., can be used as a commercially available two-part curable silicone product.

[0031] In the pneumatic tire described above, the sealant in the sealant layer 20 preferably has a glass transition temperature in the range of -120 °C to -40 °C. By using a sealant with a low glass transition temperature, the tire puncture sealing properties can be satisfactorily ensured in low-temperature environments. If the glass transition temperature of the sealant is above -40 °C, the tire puncture sealing properties deteriorate in low-temperature environments.

[0032] In the pneumatic tire described above, as in Fig.As illustrated in Figure 2, the thickness S of the sealant layer 20 can range from 2.0 mm to 5.0 mm. This makes it possible to suppress a deterioration in rolling resistance due to an increase in tire weight and to suppress uneven distribution of the sealant layer 20 due to sealant flow, while simultaneously ensuring the tire puncture sealing properties. If the thickness S of the sealant layer 20 is less than 2.0 mm, the tire puncture sealing properties are reduced, while if the thickness S is greater than 5.0 mm, the rolling resistance deteriorates due to the increase in tire weight, which may lead to uneven distribution of the sealant layer 20 due to sealant flow. It should be noted that the thickness S of the sealant layer 20 refers to an average thickness of the entire sealant layer.The average thickness of the sealant layer 20 can be calculated from measurements at a total of 40 points, for example by taking images of the tire meridian cross-section at eight locations on the tire circumference using CT scanning and measuring the thickness of the sealant layer 20 at five points in each of the images taken, namely a tire equator position, outer edge positions (both sides) in a 10 mm section from the edge of the sealant layer 20 to the inside in the tire width direction and intermediate positions (both sides) between the tire equator position and the outer edge positions.

[0033] In the pneumatic tire described above, as in Fig.As illustrated in Figure 3, when the belt layer 7 (7A, 7B), including a belt cord thread inclined with respect to the tire's circumferential direction, is embedded in the tread section 1, the inclination direction of the strip 21 of the sealant with respect to the tire's circumferential direction is preferably opposite in phase to the inclination direction of the belt cord thread of a belt layer 7A on an innermost side in the tire's radial direction with respect to the tire's circumferential direction. In the pneumatic tire, crab tread occurs due to the orientation of the belt cord thread of the belt layer 7, but the orientation of the strip 21 of the sealant also causes crab tread.Therefore, it is possible to reduce crab gait by causing the inclination direction of the strip 21 of the sealant with respect to the tire circumferential direction to be opposite to the inclination direction of the belt cord thread of the belt layer 7A on the innermost side in the tire radial direction with respect to the tire circumferential direction.

[0034] In the pneumatic tire described above, as in Fig.As illustrated in Figure 1, the width Ws of the sealant layer 20 is preferably 90% or more of the width Wb of the belt layer 7A on the innermost side in the tire radial direction. In particular, an end section of the sealant layer 20 can be located further on an outer side in the tire width direction than an end section of the belt layer 7A on the innermost side in the tire radial direction. A sufficiently large width Ws of the sealant layer 20 compared to the width Wb of the belt layer 7A can effectively prevent a puncture in the pneumatic tire. However, if the width Ws of the sealant layer 20 is less than 90% of the width Wb of the belt layer 7A, the tire puncture sealing properties deteriorate.

[0035] For the same reason, if the belt cover layer 8, including the organic fiber cord thread oriented in the tire's circumferential direction, is embedded in the tread section 1 on the outer circumferential side of the belt layer 7, the end section of the sealant layer 20 can be located further on the outside in the tire's width direction than the end section of the belt cover layer 8. A sufficiently large width of the sealant layer 20 can effectively prevent a puncture in the pneumatic tire.

[0036] With the pneumatic tire described above, as in Fig.As illustrated in Figure 2, for all sections of the belt layer 7A located on the innermost side in the tire radial direction, the distance (shortest distance) L from the belt layer 7A to the sealant layer 20 is preferably 10 mm or less. This allows the sealant to easily flow into the belt layer 7A if a foreign object, such as a nail, penetrates the tread section 1, thus ensuring good tire puncture sealing properties. If there is a section where the distance L from the first belt layer 7A to the sealant layer 20 is greater than 10 mm, the tire puncture sealing properties in that section may be inadequate.

[0037] In the pneumatic tire described above, the ratio between the thickness S of the sealant layer 20 and the distance L from the belt layer 7A on the innermost side in the tire radial direction to the sealant layer 20 preferably satisfies a relationship of S / L ≥ 0.3. By setting the thickness S of the sealant layer 20 sufficiently large with respect to the distance L, good tire puncture sealing properties can be ensured. If the ratio S / L is less than 0.3, the tire puncture sealing properties deteriorate.

[0038] Fig. Figure 6 illustrates a pneumatic tire according to a further embodiment of the present invention. Fig.6. A sound-absorbing element 40 is arranged along the circumferential direction of the tire on the inside of the sealant layer 20 in the tire radial direction. The sound-absorbing element 40 encloses a porous, open-cell material and exhibits predefined sound absorption properties based on a porous structure. Preferably, polyurethane foam is used as the porous material of the sound-absorbing element 40. The sound-absorbing element 40 is applied to the sealant layer 20 after its formation, based on the adhesion of the sealant layer 20. In this case, since the sound-absorbing element 40 is arranged on the sealant layer 20, which is applied at a low temperature, damage to the sound-absorbing element 40 can be avoided and its sound-absorbing effect can be satisfactorily maintained. Examples

[0039] For a pneumatic tire having a tire size of 255 / 45R19 and including a tread section, a pair of sidewall sections and a pair of bead sections, the tires of Comparative Example 1 and Examples 1 to 6 were manufactured by forming a sealant layer having a structure in which a strip of sealant is arranged spirally along a tire circumferential direction on an inner tire surface in the tread section, and by varying a material of the sealant layer, a thickness S of the sealant layer, a ratio of the width of the sealant layer to the width of the belt layer, an inclination direction of the strip of sealant, a distance L from the belt layer on an innermost side in the tire radial direction to the sealant layer, and a ratio S / L as shown in Table 1.A tire representing the state of the art was prepared in a tread section without a sealant layer on the inner tire surface.

[0040] Regarding the inclination direction of the sealant strip, the case in which the inclination direction of the sealant strip with respect to the tire circumferential direction coincides with the inclination direction of the belt cord thread of the belt layer on the innermost side in the tire radial direction with respect to the tire circumferential direction is indicated by "same", and the case in which the inclination direction of the sealant strip with respect to the tire circumferential direction is in opposite phase to the inclination direction of the belt cord thread of the belt layer on the innermost side in the tire radial direction with respect to the tire circumferential direction is indicated by "opposite".

[0041] For these test tires, rolling resistance, ply control and tire puncture sealing properties were evaluated by the following test procedure, and the results are shown together in Table 1. Rolling resistance:

[0042] In the rolling resistance evaluation, each of the test tires was mounted on a wheel with a rim size of 19 × 8.5J and installed on a rolling resistance testing machine. The rolling resistance was measured at an air pressure of 210 kPa according to JIS-D4234. The evaluation results are expressed as index values ​​using inverses of measured values, with the prior art example assigned an index value of 100. Higher index values ​​indicate lower rolling resistance. Crabwalk:

[0043] Each test tire was mounted on a 19 × 8.5J rim and installed on a consistency testing machine, and crab gait was measured at an air pressure of 200 kPa according to JIS-D4233. The evaluation results are expressed as index values ​​using inverses of measured values, with the prior art example assigned an index value of 100. Higher index values ​​indicate less crab gait. Tire puncture sealing properties:

[0044] Each test tire was mounted on a wheel with a rim size of 19 × 8.5J. The initial air pressure was set to 250 kPa. A nail with a diameter of 4.0 mm was driven into the tread section, and the test tire was then left for one hour in a condition in which the nail had been removed. After this time, the air pressure was measured again, and the ratio of the pressure drop to the initial air pressure was determined. For the evaluation results, “⊚” was indicated if the pressure drop ratio was 2% or less, “◯” if the pressure drop ratio was more than 2% and 7% or less, “△” if the pressure drop ratio was more than 7% and 20% or less, and “×” if the pressure drop ratio was more than 20%. [Table 1] State of the art example Comparison s-example Example Example Example Example Example Example 1 1 2 3 4 5 6 Sealant layer material - Butyl rubber silicone silicone silicone silicone silicone silicone Thickness S (mm) of the sealant layer - 2,5 2,5 2,0 3,0 5,0 2,5 2,5 Ratio (%) of the width of the sealant layer - 90 90 90 90 90 90 105 Direction of inclination of the sealant strip - Same Same Same Same Same On the contrary Same Distance L (mm) from belt layer to sealant layer - 10 10 10 10 10 10 10 S / L ratio - 0,25 0,25 0,20 0,30 0,50 0,25 0,25 Rolling resistance (index value) 100 100 100 102 100 98 100 100 Crabwalk (Index) 100 100 100 100 100 100 105 100 Tire puncture sealing properties × △ ◯ ◯ ⊚ ⊚ ◯ ⊚

[0045] As can be seen from Table 1, all tires in Examples 1 to 6 exhibited good puncture sealing properties. In contrast, the tire in Comparison Example 1 used a sealant consisting mainly of butyl rubber to form a sealant layer with a structure in which a strip of sealant is arranged spirally along the tire's circumference. Consequently, the integrity of the circumferential sections of the sealant strip was not good, resulting in inadequate sealing properties from the sealant layer. List of reference symbols 1 tread section 2 Side wall section 3 bead section 4 Carcass layer 5 bead core 6 bead fillers 7th belt layer 8 Belt cover layer 10 Tire inner surface 20 Sealant layer 21 strips of sealant 40 sound-absorbing elements QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 6583456 B

[0004] JP 6620851 B

[0004] JP 7319533 B

[0004] JP 6124967 B

[0004] JP 2018-503725 A

[0030] JP 2022-550962 A

[0030]

Claims

[1] Pneumatic tire comprising: a tread section extending in the circumferential direction of the tire and having a ring shape; a pair of sidewall sections arranged on both sides of the tread section; and a pair of bead sections arranged on an inner side of the sidewall sections in a tire radial direction, wherein a sealant layer having a structure in which a strip of sealant is arranged spirally along the circumferential direction of the tire is formed on an inner surface of the tire in the tread section, and the sealant comprising a silicone-based composition. [2] Pneumatic tire according to claim 1, wherein the silicone-based composition comprises a two-part curable silicone. [3] Pneumatic tires according to claim 1 or 2, wherein the sealing material has a glass transition temperature in the range of -120 °C to -40 °C. [4] Pneumatic tire according to any one of claims 1 to 3, wherein the sealing layer has a width in the range of 2.0 mm to 5.0 mm. [5] Pneumatic tire according to any one of claims 1 to 4, wherein a belt layer comprising a belt cord thread inclined in respect of the tire circumferential direction is embedded in the tread section and an inclination direction of the strip of the sealant in respect of the tire circumferential direction is opposite in phase to an inclination direction of a belt cord thread of a belt layer on an innermost side in the tire radial direction in respect of the tire circumferential direction. [6] Pneumatic tire according to any one of claims 1 to 5, wherein a belt layer comprises a belt cord thread inclined with respect to the tire circumferential direction, which is embedded in the tread section, and a width of the sealant layer is 90% or more of the width of a belt layer on an innermost side in the tire radial direction. [7] Pneumatic tire according to claim 6, wherein an end section of the sealing layer is located further on an outer side in a tire width direction than an end section of the belt layer on the innermost side in the tire radial direction. [8] Pneumatic tire according to claim 7, wherein a belt cover layer is embedded in the tread section on an outer circumferential side of the belt layer, comprising organic fiber cord threads oriented in the tire circumferential direction, and the end section of the sealant layer is located further outwards in the tire width direction than an end section of the belt cover layer. [9] Pneumatic tire according to any one of claims 5 to 8, wherein on all sections of the belt layer on the innermost side in the tire radial direction the distance L from the belt layer to the sealant layer is 10 mm or less. [10] Pneumatic tire according to claim 9, wherein a ratio between a thickness S of the sealant layer and the distance L from the belt layer on the innermost side in the tire radial direction to the sealant layer satisfies a relationship of S / L ≥ 0.

3. [11] Pneumatic tire according to any one of claims 1 to 10, wherein a sound-absorbing element is arranged along the circumferential direction of the tire on an inner side of the sealant layer in the radial direction of the tire. [12] Method for manufacturing the pneumatic tire according to any one of claims 1 to 10, comprising: Manufacturing the pneumatic tire exclusively of the sealant layer, and Forming the sealant layer by applying a sealant comprising a silicone-based composition to the inner surface of the tire in the tread section and adjusting the temperature of the sealant applied to the inner surface of the tire to less than 70 °C. [13] Method for manufacturing a pneumatic tire according to claim 12, further comprising arranging a sound-absorbing element along the tire circumferential direction on an inside of the sealant layer in the tire radial direction.

Images