Pneumatic tires and methods for their manufacture

Abstract

A pneumatic tire, which can reduce vulcanization defects by using a release agent and furthermore suppress the peeling of the sealant layer, and a manufacturing process for 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 side of the sidewall sections (2) in a radial direction, and has an inner tire surface (10) onto which a release agent (16) containing particles (15) is applied.A sealant layer (20) is formed on an inner tire surface (10) in the tread section (1), a sealant of the sealant layer (20) consists of a silicone-based composition, and the particles (15) applied to a region to form the sealant layer (20) are present in the sealant layer (20) in a mixed state.

Description

Technical field

[0001] The present invention relates to a pneumatic tire including a sealant layer on an inner tire surface in a tread section and a manufacturing method therefor, and relates in particular to a pneumatic tire which can reduce vulcanization defects by using a release agent and furthermore suppress the peeling of the sealant layer, and to a manufacturing method for the pneumatic tire. 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).

[0004] However, during the manufacturing of a pneumatic tire, a release agent containing particles such as talc or mica is applied to the inner surface of an unvulcanized tire. This release agent remains on the inner surface of the tire after vulcanization, causing the sealant layer to tend to peel away from the inner surface due to the action of the release agent. While it is conceivable to remove the remaining release agent from the inner surface before the sealant layer forms, this increases the labor required, negatively impacting productivity.Furthermore, instead of applying the release agent directly to the inner surface of the tire, it is possible to prevent its adhesion by providing a blister with release properties. However, these release properties tend to deteriorate during the continuous production of pneumatic tires, which can lead to vulcanization defects. Therefore, it is still necessary to apply the release agent to the inner surface of the unvulcanized tire, and it is an unavoidable fact that the release agent will remain on the inner surface of the tire after vulcanization. List of literature on patent literature Patent document 1: JP 6583456 B Patent document 2: JP 6620851 B Patent Document 3: JP 7319533 B Brief description of the invention: Technical problem

[0005] One object of the present invention is to provide a pneumatic tire which can reduce vulcanization defects by using a release agent and furthermore suppress the peeling of a sealant layer, and a manufacturing method for the pneumatic tire. Solution to the problem

[0006] A pneumatic tire according to the present invention for fulfilling the above 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 the pneumatic tire has an inner tire surface on which a release agent containing particles is applied, wherein a sealant layer is formed on the inner tire surface in the tread section, wherein a sealant of the sealant layer includes a silicone-based composition, and the particles applied to a region for forming the sealant layer are present in a mixed state in the sealant layer.

[0007] A manufacturing method for a pneumatic tire according to the present invention for fulfilling the above objective, wherein the method includes: Forming an unvulcanized tire corresponding to a pneumatic tire, comprising a tread section extending in a 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 inside of the sidewall sections in a tire radial direction; Vulcanizing the unvulcanized tire in a state where a release agent containing particles is applied to an inner surface of the unvulcanized tire to produce the pneumatic tire; and Forming a sealant layer by applying a sealant including a silicone-based composition to an inner tire surface in the tread section, wherein the particles applied to a region for forming the sealant layer are incorporated into the sealant layer. Advantageous effects of the invention

[0008] In the present invention, in a pneumatic tire having an inner surface to which a release agent containing particles is applied, a sealant layer containing a sealant consisting of a silicone-based composition is formed on the inner surface of the tire in a tread section, and the particles applied to a region to form the sealant layer are present in a mixed state in the sealant layer.This means that when a pneumatic tire is manufactured by vulcanizing an unvulcanized tire in a state where a release agent containing particles is applied to the inner surface of the unvulcanized tire, and then the sealant layer is formed by applying the sealant, which consists of a silicone-based composition, to the inner surface of the tire in the tread area, the particles applied to the area for forming the sealant layer are incorporated into the sealant layer. If the sealant consists of a rubber composition that mainly contains butyl rubber, the particles are not incorporated into the sealant layer. However, if the sealant consists of a silicone-based composition, the sealant acts in such a way that it incorporates the particles contained in the release agent as the applied sealant layer cures.This prevents an uneven distribution of the release agent particles at the interface between the inner tire surface and the sealant layer, and thus prevents the sealant layer from peeling off the inner tire surface. According to the present invention, vulcanization defects can be prevented by using the release agent, and since the release agent does not need to be removed from the inner tire surface, the tire's productivity is not affected.

[0009] In the present invention, the release agent preferably comprises the silicone-based composition. When the release agent contains the silicone-based composition, vulcanization defects can be effectively reduced, and since the release agent, which consists of the silicone-based composition, is readily incorporated into the sealant layer containing the sealant, which also consists of the silicone-based composition, peeling of the sealant layer can be effectively suppressed.

[0010] In the present invention, the weight of the sealant layer is preferably 10 times or more the weight of the particles applied to a region for forming the sealant layer. By sufficiently increasing the ratio between the weight of the sealant layer and the weight of the particles, the particles are more easily incorporated into the sealant layer, and thus peeling of the sealant layer can be effectively suppressed.

[0011] 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 mixing the two liquids, it can also be applied at low temperatures. Furthermore, mixing the two liquids reduces the mixing time and stabilizes (uniforms) the thickness of the sealant layer after curing.

[0012] In the present invention, if a belt layer, including a belt cord thread inclined to the tire circumference, is embedded in the tread section, the distance L from the belt layer to the sealant layer on an innermost side in the tire radial direction is preferably 10 mm or less in all sections of a belt layer. This allows the sealant to easily flow into the belt layer if a foreign body, such as a nail, penetrates the tread section, thus ensuring good tire puncture sealing properties.

[0013] 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.

[0014] 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, it is possible to prevent the adhesion of foreign material to the sealant layer and simultaneously achieve a sound-absorbing effect based on the sound-absorbing element. 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. Figure 3 is an enlarged cross-sectional view showing an inner liner layer, a release agent layer, and a sealant layer of the pneumatic tire. Fig. 1 illustrates. Fig. 4 is a cross-sectional view showing a manufacturing process for 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

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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 cords are preferably used as the belt cords of the belt layers 7.

[0019] 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.

[0020] It should be noted that the tire internal structure described above is a typical example for pneumatic tires, but pneumatic tires are not limited to this. Furthermore, an inner liner layer 9 (air penetration protection layer) is arranged along the inside of the carcass layer 4. 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.

[0021] In the pneumatic tire described above, as in Fig.As illustrated in Figure 3, a release agent 16 containing particles 15 is applied to the inner surface 10 of the tire. The release agent 16 may, if necessary, contain a silicone-based composition, a surfactant, and the like in addition to the particles 15. These components are dispersed in water when the release agent is applied to the inner surface of an unvulcanized tire, but the water has evaporated in a vulcanized tire. Examples of the particles 15 include talc, mica, carbon black, and aluminum oxide. The particles 15 are effective as a release agent if they are in powder form and may have a spherical, plate-like, rod-shaped, or other form. The largest dimension of the particles 15 is preferably 1 mm or less. The electrically conductive particles 15 preferably contribute to a reduction in the electrical resistance of the pneumatic tire.

[0022] 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. The 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. 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.At least some of the particles 15 applied to a region to form the sealant layer 20 are then present in the sealant layer 20 in a mixed state.

[0023] The pneumatic tire described above can be manufactured by the following process. First, the pneumatic tire is manufactured by forming an unvulcanized tire corresponding to the pneumatic tire, comprising the tread section 1, the two sidewall sections 2, and the two bead sections 3 as described above, and in which the belt layer 7 and the belt cover layer 8 are embedded in the tread section 1; and vulcanizing the unvulcanized tire in a state in which the release agent 16, containing the particles 15, is applied to the inner surface of the unvulcanized tire. 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.Accordingly, the particles 15, which were applied to the region to form the sealant layer 20, are incorporated into the sealant layer 20 when the sealant of the sealant layer 20 cures after application.

[0024] In the pneumatic tire, which has an inner surface 10 onto which the release agent 16 containing particles 15 is applied in this manner, the sealant layer 20, which contains a sealant consisting of a silicone-based composition, is formed on the inner surface 10 in the tread section 1, and the particles 15 applied to the region for forming the sealant layer 20 are present in a mixed state within the sealant layer 20. This prevents an uneven distribution of the particles 15 of the release agent 16 at an interface between the inner surface 10 and the sealant layer 20 and prevents the sealant layer 20 from peeling off the inner surface 10.Furthermore, vulcanization defects can be reduced by using the release agent 16, and since the release agent 16 does not need to be removed from the inner surface of the tire 10, the productivity of the tire is not affected.

[0025] In the pneumatic tire described above, the release agent 16 preferably contains a silicone-based composition. When the release agent 16 contains the silicone-based composition, vulcanization defects can be effectively reduced, and since the release agent 16, which consists of the silicone-based composition, is readily incorporated into the sealant layer 20, which contains the sealant that also consists of the silicone-based composition, peeling of the sealant layer 20 can be effectively suppressed.

[0026] In the pneumatic tire described above, the weight of the sealant layer 20 is preferably 10 times or more the weight of the particles 15 applied to the region for forming the sealant layer 20. By sufficiently increasing the ratio between the weight of the sealant layer 20 and the weight of the particles 15, the particles 15 are more readily incorporated into the sealant layer 20, and thus peeling of the sealant layer 20 can be effectively suppressed. If the ratio between the weight of the sealant layer 20 and the weight of the particles 15 is less than 10 times, the particles 15 are hardly incorporated into the sealant layer 20. In particular, the ratio between the weight of the sealant layer 20 and the weight of the particles 15 is preferably 25 times or more, more preferably 50 times or more, and preferably has an upper limit of 110 times.

[0027] Fig. Figure 4 illustrates a specific manufacturing process for the pneumatic tire of Fig. 1, and Fig. Figure 5 illustrates a 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 Figure 4). 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.

[0028] 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 easily adapt 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[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 a 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] If the pneumatic tire described above, as in Fig.As illustrated in Figure 2, where the belt layer 7 (7A, 7B), including the belt cord thread inclined to the tire's circumferential direction, is embedded in the tread section 1, the distance (shortest distance) L from the belt layer 7A to the sealant layer 20 is preferably 10 mm or less for all sections of a belt layer 7A located on the innermost side in the tire's radial direction. 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 belt layer 7A to the sealant layer 20 is greater than 10 mm, the tire puncture sealing property 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 in relation 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 a sealant layer 20 in a radial direction. The sound-absorbing element 40 encloses a porous, open-cell material and exhibits predefined sound absorption properties based on its 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, it is possible to prevent the adhesion of foreign material to the sealant layer 20 while simultaneously achieving a sound-absorbing effect based on the sound-absorbing element 20. Examples

[0039] The manufacture of pneumatic tires, each having a tire size of 255 / 45R19 and each comprising a tread section, a pair of sidewall sections, and a pair of bead sections, wherein the presence of a release agent applied to an inner tire surface; the type of release agent; a material component of a sealant layer; a ratio of the weight of the sealant layer to a weight (20 g) of particles applied to a region to form the sealant layer; a thickness S of the sealant layer; a distance L from a belt layer on an innermost side in a tire radial direction to the sealant layer; and a ratio S / L have been varied as specified in Table 1 (Comparison Examples 1 and 2 and Examples 1 to 6). A composition of the release agent is given in Table 2.In comparative example 2, instead of applying the release agent to the surface of the tire, an outer surface of a bladder of a tire vulcanizing device was subjected to a release treatment.

[0040] For these test tires, vulcanization defects, peel resistance and tire puncture sealing properties were evaluated by the following test procedures, and the results are summarized in Table 1. Vulcanization defects:

[0041] The frequency of vulcanization defects was determined after the continuous vulcanization of 400 test tires. The evaluation result was indicated as “⊚” if the frequency of vulcanization defects was 0%, “◯” if the frequency of vulcanization defects was more than 0% and less than 1%, “△” if the frequency of vulcanization defects was 1% or more and less than 5%, and “×” if the frequency of vulcanization defects was 5% or more. Resistance to peeling:

[0042] Each test tire was mounted on a 19 × 8.5J rim, installed on an indoor drum tire testing machine (drum diameter of 1707 mm), and driven for 6000 km under controlled ambient temperature conditions of 38 ± 3 °C, tire pressure of 120 kPa, a load of 120% of the maximum load capacity, and a speed of 80 km / h. The sealant layer on the inner surface of the tire was then observed. Evaluation results were indicated with “⊚” if there was no lifting or misalignment in the sealant layer, “◯” if there was no lifting in the sealant layer and the misalignment was less than 5 cm, and “×” if there was lifting in the sealant layer or the misalignment was 5 cm or more. Tire puncture sealing properties:

[0043] 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. The evaluation results were indicated with "⊚" 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] Comparative example 1 Comparative example 2 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Presence of release agent Available Unavailable Available Available Available Available Available Available Type of release agent A - A B C A A A Sealant layer material Butyl rubber Butyl rubber silicone silicone silicone silicone silicone silicone Weight ratio (%) of the sealant layer 50 50 50 50 50 25 10 66 Thickness S (mm) of the sealant layer 2,3 2,3 2,3 2,3 2,3 1,2 0,5 3,0 Distance L (mm) from belt layer to sealant layer 10 10 10 10 10 10 10 10 S / L ratio 0,23 0,23 0,23 0,23 0,23 0,12 0,05 0,3 Vulcanization defects ◯ × ◯ ◯ ⊚ ◯ ◯ ◯ peel resistance × ◯ ◯ ◯ ⊚ ◯ ◯ ◯ Tire puncture sealing properties △ △ ◯ ◯ ◯ ◯ △ ⊚ [Table 2] (weight parts) Release agent A Release agent B Release agent C Water 100 100 100 talc powder 100 - 100 mica powder - 100 - silicone emulsion - - 17 surfactant 4 4 4

[0044] As shown in Table 1, all tires in Examples 1 to 6 exhibited very few vulcanization defects, and peeling of the sealant layer was sufficiently suppressed. In contrast, although the release agent containing particles was applied to the inner surface of the tire in Comparison Example 1, a butyl-based rubber sealant was used, resulting in peeling of the sealant layer. In Comparison Example 2, a release agent treatment was applied to the outer surface of a blister to avoid using the release agent itself, and consequently, the incidence of vulcanization defects was high during continuous vulcanization. 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 9 Inner Soul Layer 10 Tire inner surface 15 particles 16 release agents 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 2018-503725 A

[0031] JP 2022-550962 A

[0031]

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, the pneumatic tire having an inner surface on which a release agent containing particles is applied, a sealant layer being formed on the inner surface of the tire in the tread section, a sealant of the sealant layer comprising a silicone-based composition, and the particles applied to a region for the formation of the sealant layer being present in a mixed state in the sealant layer. [2] Pneumatic tires according to claim 1, wherein the release agent comprises a silicone-based composition. [3] Pneumatic tire according to claim 1 or 2, wherein the weight of the sealant layer is 10 times or more the weight of the particles applied to the region to form the sealant layer. [4] Pneumatic tires according to any one of claims 1 to 3, wherein the silicone-based composition comprises a two-part curable silicone. [5] Pneumatic tire according to any one of claims 1 to 4, wherein a belt layer including a belt cord thread inclined to the tire circumferential direction is embedded in the tread section and in all sections of a belt layer, on an innermost side in the tire radial direction, a distance L from the belt layer to the sealant layer is 10 mm or less. [6] Pneumatic tire according to claim 5, 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. [7] Pneumatic tire according to any one of claims 1 to 6, 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. [8] Manufacturing process of an pneumatic tire, the process comprising: Forming an unvulcanized pneumatic tire that is equivalent to a pneumatic tire, which consists of a tread section extending in a circumferential direction of the tire and having a ring shape, a pair of sidewall sections arranged on both sides of the tread section, and comprising a pair of bead sections, each arranged on an inside sidewall section in a tire radial direction; Vulcanizing the unvulcanized tire in a state where a release agent containing particles is applied to an inner surface of the unvulcanized tire to produce the pneumatic tire; and Forming a sealant layer by applying a sealant including a silicone-based composition to an inner tire surface in the tread section, wherein the particles, which were applied to a region to form the sealant layer, are incorporated into the sealant layer. [9] Manufacturing process for a pneumatic tire according to claim 8, wherein the release agent comprises a silicone-based composition. [10] Manufacturing method for a pneumatic tire according to claim 8 or 9, wherein the weight of the sealant layer is 10 times or more the weight of the particles applied to the region to form the sealant layer. [11] Manufacturing method for an air tire according to one of claims 8 to 10, wherein the silicone-based composition comprises a two-part curable silicone. [12] Manufacturing method for a pneumatic tire according to one of claims 8 to 11, wherein a belt layer including a belt cord thread inclined to the tire circumferential direction is embedded in the tread section and in all sections of a belt layer, on an innermost side in the tire radial direction, a distance L from the belt layer to the sealant layer is 10 mm or less. [13] Manufacturing method for a pneumatic tire according to claim 12, 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. [14] Manufacturing method for a pneumatic tire according to one of claims 8 to 13, further comprising: arranging a sound-absorbing element along the tire circumferential direction on an inner side of the sealant layer in the tire radial direction.

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