Pneumatic tire and method for manufacturing same

Abstract

The present invention provides a pneumatic tire and a method for manufacturing the same, in which a sound-absorbing material is adhered in a state in which a release agent is adhered to the inner surface of the tire, whereby both air retention and adhesiveness of the sound-absorbing material can be achieved without deteriorating tire productivity. A pneumatic tire vulcanized using a bladder provided with a coating layer formed from a release agent, in which a sound-absorbing material (6) is affixed to the inner surface of a tread portion (1) in the tire circumferential direction via an adhesive layer (7), and the silicon content of the release agent detected by X-ray fluorescence analysis at least in the affixed region of the sound-absorbing material (6) is 0.1-10.0 wt%.

Description

[0001] This application is a divisional application of Chinese patent application filed on November 14, 2017, with application number 201780085640.9 and invention title: "Pneumatic Tire and Method for Manufacturing the Same". Technical Field

[0002] This invention relates to a pneumatic tire and a method for manufacturing the same, and more specifically, to a method for manufacturing the same pneumatic tire and a method for bonding a sound-absorbing component while a release agent is applied to the inner surface of the tire, thereby achieving both air retention and adhesion of the sound-absorbing component without deteriorating tire productivity. Background Technology

[0003] One cause of tire noise is cavity resonance, resulting from the vibration of the air filling the tire cavity. When a vehicle is in motion, the tire tread vibrates due to the unevenness of the road surface, causing the air inside the tire cavity to vibrate and produce this cavity resonance. This cavity resonance contains a frequency range that constitutes noise, and reducing the noise level within this frequency range is important for reducing tire noise.

[0004] As a method to reduce noise caused by such cavity resonance, a solution has been proposed in which a sound-absorbing element made of porous material such as sponge is attached to the inner circumferential surface of the tire tread via an elastic fixing band (for example, see Patent Document 1). However, when the fixing of the sound-absorbing element depends on the elastic fixing band, there is a problem that the elastic fixing band deforms at high speeds.

[0005] On the other hand, when using airbags to vulcanize green tires, the airbags tend to stick to the inner surfaces of the green tire. Therefore, a release agent is applied to the inner surface of the green tire to prevent this sticking. In this case, if the sound-absorbing component is directly bonded and fixed to the inner surface of the tire, there is a problem that the adhesion between the tire's inner surface with the release agent and the sound-absorbing component is poor, and the sound-absorbing component is prone to peeling off.

[0006] In contrast, a method has been proposed that involves applying a release agent to the inner surface of the green tire and removing it by polishing the inner surface after vulcanization (e.g., Patent Document 2). However, such polishing also reduces the thickness of the inner liner, thus deteriorating air retention. Furthermore, a method has been proposed that involves pre-applying a film to the inner surface of the green tire, applying a release agent to the inner surface while the film is applied, and removing the release agent by peeling off the film after vulcanization (e.g., Patent Document 3). However, the need to peel off the film after vulcanization increases manufacturing time, thus reducing tire productivity. Additionally, a method has been proposed that involves cleaning the inner surface of the tire with the applied release agent, but this method cannot adequately remove the release agent and results in poor tire productivity.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent No. 4281874

[0010] Patent Document 2: Japanese Patent No. 4410753

[0011] Patent Document 3: Japanese Patent Application Publication No. 2015-107690 Summary of the Invention

[0012] The problem the invention aims to solve

[0013] The purpose of this invention is to provide a pneumatic tire and a method for manufacturing the same, in which a sound-absorbing component is bonded to the inner surface of the tire while a release agent is attached, thereby achieving both air retention and adhesion of the sound-absorbing component without deteriorating tire productivity.

[0014] Technical solution

[0015] The pneumatic tire of the present invention for achieving the above-mentioned objectives is a pneumatic tire vulcanized using an air bladder having a coating formed by a release agent, characterized in that a sound-absorbing element is fixed to the inner surface of the tread along the tire circumference via an adhesive layer, and the amount of silicon in the release agent, as detected by X-ray fluorescence analysis, is 0.1% to 10.0% by weight in at least the fixed area of ​​the sound-absorbing element.

[0016] The method for manufacturing a pneumatic tire of the present invention is a method for manufacturing a pneumatic tire by using an air bladder having a coating formed by a release agent to vulcanize a green tire. The method is characterized in that, when fixing a sound-absorbing element to the inner surface of the tread of the vulcanized pneumatic tire, the amount of silicon in the release agent, as detected by X-ray fluorescence analysis, is 0.1% to 10.0% by weight in at least the fixing area of ​​the sound-absorbing element, and the sound-absorbing element is fixed in the fixing area of ​​the sound-absorbing element along the tire circumferential direction via an adhesive layer.

[0017] Beneficial effects

[0018] In this invention, by using an airbag with a coating formed by a release agent for vulcanization, the amount of silicon in the release agent in at least the fixed area of ​​the sound-absorbing element can be 0.1% to 10.0% by weight. Thus, even when a small amount of release agent adheres to the inner surface of the tire, the release agent prevents air from permeating from the inner surface of the tire, resulting in good air retention. On the other hand, sufficient adhesion between the inner surface of the tire and the sound-absorbing element can be ensured. Furthermore, according to this invention, unlike conventional methods such as polishing the inner surface of the tire, applying a film to the inner surface of the tire, or cleaning the inner surface of the tire, tire productivity is not deteriorated. As a result, both air retention and adhesion of the sound-absorbing element can be achieved without deteriorating tire productivity.

[0019] In this invention, it is preferred that the peel adhesion strength of the adhesive layer is 5N / 20mm to 100N / 20mm. This allows for good maintenance of the sound-absorbing component's fixation strength while facilitating the bonding process and disassembly of the component when using discarded tires. The peel adhesion strength of the adhesive layer is measured according to JIS-Z0237. Specifically, a 25µm thick PET film is laminated to reinforce the double-sided adhesive sheet. The reinforced adhesive sheet is then cut into 20mm × 200mm squares to create test pieces. The peel lining is peeled off from the test piece, and a 2kg roller is used for one reciprocating motion, exposing the adhesive surface to a stainless steel (SUS304, surface finished BA) plate as the substrate. After maintaining it at 23°C (standard conditions) and 50% RH for 30 minutes, the 180° peel bond strength to the SUS board was measured using a tensile testing machine according to JIS-Z0237 at 23°C and 50% RH, with a peel angle of 180° and a tensile speed of 300 mm / min.

[0020] In this invention, it is preferable that the adhesive layer is formed of double-sided adhesive tape, and the total thickness of the adhesive layer is 10µm to 150µm. This ensures adaptability to deformation during molding.

[0021] In this invention, it is preferable that the adhesive layer is formed of a double-sided tape containing only adhesive or a double-sided tape containing both adhesive and non-woven fabric. With a double-sided tape containing only adhesive, heat dissipation is not hindered, thus suppressing the deterioration of high-speed durability and providing excellent responsiveness to tire deformation. Furthermore, with a double-sided tape containing both adhesive and non-woven fabric, both high-speed durability and responsiveness can be achieved.

[0022] In this invention, it is preferable that the center position of the sound-absorbing element in the width direction is located within a range of ±10 mm relative to the tire equator. By arranging the sound-absorbing element as described above, tire uniformity will not be deteriorated. In particular, it is more preferable that it is located within a range of ±5 mm relative to the tire equator.

[0023] In this invention, it is preferable that the volume of the sound-absorbing component is 10% to 30% of the tire's inner cavity volume. This further enhances the sound absorption effect achieved by the sound-absorbing component. Thus, by increasing the volume of the sound-absorbing component, excellent noise reduction is achieved, and even large sound-absorbing components maintain good adhesion over a long period. The tire's inner cavity volume is the volume of the cavity formed between the tire and the rim when the tire and rim are assembled onto a standard rim and filled with the standard internal pressure. A "standard rim" refers to a rim specified for the tire within a specification system that includes the tire's base specifications; for example, a JATMA rim is designated as a standard rim, a TRA rim as a "Design Rim," or an ETRTO rim as a "Measuring Rim." However, when the tire is installed on a new vehicle, the volume of the cavity is determined using the original factory wheel with the tire installed. "Standard tire pressure" refers to the tire pressure specified for each specification within the tire specification system. For JATMA, it is the maximum tire pressure; for TRA, it is the maximum value recorded in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES"; and for ETRTO, it is "INFLATION PRESSURE". However, when the tire is installed on a new vehicle, it is set to the tire pressure displayed on the vehicle.

[0024] In this invention, it is preferred that the hardness of the sound-absorbing component is 80N to 150N, the tensile strength is 90kPa or higher, and the elongation at break is 200% or higher. Sound-absorbing components with these physical properties exhibit excellent durability against expansion caused by tire inflation and shear strain on the adhesive surface caused by ground rotation. The hardness, tensile strength, and elongation at break of the sound-absorbing component were measured according to JIS-K6400.

[0025] In this invention, it is preferable that the sound-absorbing element has a missing portion at at least one location in the tire circumferential direction. This allows it to withstand prolonged exposure to expansion caused by tire inflation and shear strain on the adhesive surface caused by ground rotation.

[0026] In this invention, preferably, during the process of forming the coating on the airbag, the coating coverage time t (hour) and temperature T (°C) satisfy the conditions t ≥ -0.0571T + 9.14 and 10°C ≤ T ≤ 180°C. Therefore, in an airbag with a coating, the time for applying the release agent can be shortened, and the shortening of the airbag's service life can be prevented. Attached Figure Description

[0027] [ Figure 1 ] Figure 1This is a perspective cross-sectional view showing an inflatable tire constructed according to an embodiment of the present invention.

[0028] [ Figure 2 ] Figure 2 This is an equatorial cross-sectional view showing an inflatable tire constructed according to an embodiment of the present invention.

[0029] [ Figure 3 ] Figure 3 This is an enlarged cross-sectional view showing a portion of an inflatable tire constructed according to an embodiment of the present invention. Detailed Implementation

[0030] Hereinafter, the structure of the present invention will be described in detail with reference to the accompanying drawings. Figures 1-3 This is a diagram showing an inflatable tire constructed according to an embodiment of the present invention. Figure 1 In this embodiment, the pneumatic tire includes: a tread portion 1 extending circumferentially and forming a ring; a pair of sidewall portions 2 disposed on both sides of the tread portion 1; and a pair of bead portions 3 disposed radially inside these sidewall portions 2. Furthermore, a [missing information - likely a tire type] is fitted into the cavity portion 4 formed by the tread portion 1, the sidewall portions 2, and the bead portions 3. Figure 2 The ring-shaped sound-absorbing element 6 is shown. This sound-absorbing element 6 is disposed on the inner surface 5 of the tire, in the area corresponding to the tread portion 1.

[0031] A sound-absorbing element 6 is fixed along the tire circumference in the region corresponding to the tread portion 1 on the inner surface 5 of the tire via an adhesive layer 7. The sound-absorbing element 6 is made of a porous material with continuous air bubbles and has specified sound-absorbing characteristics based on its porous structure. Foamed polyurethane is preferably used as the porous material for the sound-absorbing element 6. On the other hand, the adhesive layer 7 is not particularly limited; for example, adhesives or double-sided tape can be used.

[0032] like Figure 3 As shown, in the aforementioned pneumatic tire, a release agent transfer layer 8 exists between the tire inner surface 5 and the adhesive layer 7. That is, the sound-absorbing element 6, the adhesive layer 7, and the release agent transfer layer 8 are sequentially stacked starting from the radially inner side of the tire. By using an airbag with a coating formed by the release agent to vulcanize the green tire, the release agent transfer layer 8 is transferred to the tire inner surface 5 in the vulcanized pneumatic tire. In this way, the transferred release agent is not transferred to the entire surface of the tire inner surface 5, but rather dispersed across the tire inner surface 5.

[0033] The amount of silicone in the release agent transferred to the inner surface of the tread 1 is 0.1% to 10.0% by weight in a fixed area of ​​at least the sound-absorbing element 6 on the inner surface 5 of the tire. In this invention, when specifying the amount of release agent on the inner surface of the tread 1, the amount of silicone, which is the main component of a typical release agent, is used as an indicator. The amount of silicone can be detected using X-ray fluorescence analysis. Generally, X-ray fluorescence analysis methods include the FP method (basic parameter method) and the calibration curve method. In this invention, the FP method is used. When determining the amount of release agent (silicone), sheet samples (size: width 70 mm, length 100 mm) obtained by peeling off the carcass layer and the inner liner layer at multiple locations (e.g., four locations in the tire circumference and three locations in the tire width direction, for a total of seven locations) of the pneumatic tire are used. From each sheet sample, five test samples (size: width 13 mm to 15 mm, length 35 mm to 40 mm) are further extracted from four corners and one central location. The amount of release agent in each test sample is determined using an X-ray fluorescence analysis device. Then, by averaging the measured values ​​of five samples for each sheet material, the amount of release agent for each sheet material was calculated, with the calculated values ​​ranging from 0.1 wt% to 10.0 wt%. Furthermore, fluorescent X-ray particles possess intrinsic energies proportional to their atomic numbers; by measuring these intrinsic energies, elements can be identified. Specifically, the intrinsic energy of silicon is 1.74 ± 0.05 keV. It should be noted that the number of fluorescent X-ray particles (X-ray intensity) of the release agent (silicon) ranges from 0.1 cps / µA to 1.5 cps / µA.

[0034] As a component that can be incorporated into the transfer layer 8 formed by the release agent, examples include components containing an organosilicon as an active ingredient. Examples of organosilicon components include polysiloxanes, such as dialkyl polysiloxanes, alkylphenyl polysiloxanes, alkylaralkyl polysiloxanes, and 3,3,3-trifluoropropylmethyl polysiloxane. Examples of dialkyl polysiloxanes include dimethyl polysiloxane, diethyl polysiloxane, methyl isopropyl polysiloxane, and methyl dodecyl polysiloxane. Examples of alkylphenyl polysiloxanes include methylphenyl polysiloxane, dimethylsiloxane / methylphenylsiloxane copolymer, and dimethylsiloxane / diphenylsiloxane copolymer. Examples of alkylaralkyl polysiloxanes include methyl (phenylethyl) polysiloxane and methyl (phenylpropyl) polysiloxane. These polysiloxanes can be used in combination, one or more of them.

[0035] As described above, by using an airbag with a coating formed by a release agent for vulcanization, the amount of silicon in the release agent in the fixed area of ​​the sound-absorbing element 6 can be at least 0.1% to 10.0% by weight. In this way, even when a small amount of release agent adheres to the inner surface 5 of the tire, the release agent prevents air from passing through the inner surface 5 of the tire, resulting in good air retention. On the other hand, it ensures sufficient adhesion between the inner surface 5 of the tire and the sound-absorbing element 6. Here, if the amount of silicon in the release agent in the fixed area of ​​the sound-absorbing element 6 is less than 0.1% by weight, the air retention will not be improved; if the amount of silicon is more than 10.0% by weight, the adhesion of the sound-absorbing element 6 will deteriorate, and sufficient durability will not be achieved.

[0036] Furthermore, unlike conventional methods that involve polishing the inner surface of the tire, applying a film to the inner surface, or cleaning the inner surface, tire productivity is not negatively impacted. As a result, both air retention and the adhesion of the sound-absorbing component 6 are maintained without compromising tire productivity. In contrast, conventional methods, by removing the release agent adhering to the inner surface of the tire, add processing time to each step, thus worsening tire productivity compared to fixing the sound-absorbing component while it still has release agent adhering, as in this invention.

[0037] In the aforementioned pneumatic tire, the peel adhesion force of the adhesive layer 7 is preferably 5 N / 20 mm to 100 N / 20 mm. By appropriately setting the peel adhesion force of the adhesive layer 7, the fixing strength of the sound-absorbing component 6 can be well maintained, while the bonding and disassembly of the sound-absorbing component 6 can be easily performed. As the adhesive forming the adhesive layer 7, acrylic adhesives, rubber adhesives, and silicone adhesives can be listed, and it is preferable that the adhesive layer 7 is composed of any of these adhesives. In particular, silicone adhesives are preferred because even if residual release agent remains, there is no temperature dependence on adhesion, thus resulting in excellent adhesion to the sound-absorbing component 6. Furthermore, acrylic adhesives have excellent heat resistance, making them suitable for high-speed applications.

[0038] The adhesive layer 7 is formed of double-sided adhesive tape, and its total thickness is preferably 10µm to 150µm. This configuration ensures adaptability to deformation during molding. If the total thickness of the adhesive layer 7 is less than 10µm, the double-sided adhesive tape lacks sufficient strength and cannot adequately ensure adhesion to the sound-absorbing component 6. If the total thickness of the adhesive layer 7 exceeds 150µm, it hinders heat dissipation during high-speed operation, thus easily deteriorating high-speed durability.

[0039] Preferably, the adhesive layer 7 is formed of a double-sided tape containing only adhesive, or a double-sided tape containing both adhesive and non-woven fabric. In the case of a double-sided tape containing only adhesive (in the case of a double-sided tape without a substrate serving as a support for the adhesive), heat dissipation is not hindered, thus suppressing the deterioration of high-speed durability and providing good responsiveness to tire deformation. Furthermore, in the case of a double-sided tape containing both adhesive and non-woven fabric (in the case of a double-sided tape with non-woven fabric as the substrate), both high-speed durability and responsiveness can be balanced. Here, when the substrate is formed of a rigid material such as polyethylene terephthalate (PET), peeling easily occurs between the substrate and the adhesive, or between the tire and the adhesive, relative to tire deformation, leading to the detachment of the sound-absorbing element 6. Furthermore, when the substrate has low tensile strength and elongation at break, the substrate itself may sometimes be damaged. When the substrate is formed of acrylic foam, the thickness increases, thus easily deteriorating high-speed durability.

[0040] In the aforementioned pneumatic tire, it is preferable that the hardness of the sound-absorbing element 6 is 80N to 150N, the tensile strength of the sound-absorbing element 6 is 90kPa or more, and the elongation at break of the sound-absorbing element 6 is 200% or more. Sound-absorbing elements 6 with these physical properties exhibit excellent durability against the expansion caused by tire inflation and the shear strain of the adhesive surface caused by ground rotation. However, if the hardness of the sound-absorbing element 6 is less than 80N, it is prone to compression deformation due to centrifugal force during driving; if the hardness of the sound-absorbing element 6 exceeds 150N, it may sometimes fail to adapt to the deformation of the tire during driving and break.

[0041] Preferably, the center position of the sound-absorbing element 6 in the width direction is located within ±10 mm of the tire equator; more preferably, it is located within ±5 mm of the tire equator. By arranging the sound-absorbing element 6 as described above, tire uniformity will not be deteriorated.

[0042] Preferably, the volume of the sound-absorbing element 6 is 10% to 30% of the tire's inner cavity volume. More preferably, the width of the sound-absorbing element 6 is 30% to 90% of the tire's contact patch width. This further enhances the sound absorption effect achieved by the sound-absorbing element 6. If the volume of the sound-absorbing element 6 is less than 10% of the tire's inner cavity volume, an adequate sound absorption effect cannot be obtained. Furthermore, if the volume of the sound-absorbing element 6 is greater than 30% of the tire's inner cavity volume, the noise reduction effect caused by cavity resonance is fixed, and further reduction cannot be expected.

[0043] like Figure 2As shown, preferably, the sound-absorbing element 6 has a missing portion 9 at at least one location in the tire circumference. The missing portion 9 refers to a part of the tire circumference where the sound-absorbing element 6 is absent. By providing a missing portion 9 in the sound-absorbing element 6, it can withstand the expansion caused by tire inflation and the shear strain on the adhesive surface caused by ground rotation over a long period, effectively mitigating the shear strain generated on the adhesive surface of the sound-absorbing element 6. It is preferable to provide one or three to five such missing portions 9 on the tire circumference. That is, when two missing portions 9 are provided on the tire circumference, the tire uniformity will significantly deteriorate due to mass imbalance; when six or more missing portions 9 are provided on the tire circumference, the manufacturing cost will significantly increase.

[0044] It should be noted that when there are two or more missing parts 9 on the tire circumference, the sound-absorbing part 6 is interrupted in the tire circumferential direction. However, even in this case, if multiple sound-absorbing parts 6 are connected to each other by other laminates such as adhesive layer 7 formed by double-sided tape, these sound-absorbing parts 6 can be used as a single component. Therefore, it is easy to perform the pasting operation to the inner surface 5 of the tire.

[0045] Next, the manufacturing method of the pneumatic tire of the present invention will be described. During the vulcanization of the green tire, a release agent is pre-coated (preferably baked) onto the air bladder, forming a coating of the release agent on the outer surface of the air bladder. This coating formation process on the outer surface of the air bladder is performed, for example, simultaneously with the conditions of storing the air bladder at 150°C for one hour, at 90°C for four hours, or at room temperature for eight hours after applying the release agent. Furthermore, the coating formation process on the outer surface of the air bladder is performed more than once and no more than three times. The green tire is vulcanized using an air bladder with the coating formed as described above. Then, in the vulcanized tire, the sound-absorbing element 6 is fixed along the tire circumferential direction via an adhesive layer 7 in the fixing area of ​​the sound-absorbing element 6 on the inner surface 5 of the tread portion 1.

[0046] As described above, by using an airbag with a coating formed by a release agent for vulcanization, the amount of silicon in the release agent in the fixed area of ​​the sound-absorbing element 6 can be 0.1% to 10.0% by weight. As described above, when a small amount of release agent is adhered to the inner surface 5 of the tire, the release agent prevents air from passing through the inner surface 5, resulting in good air retention. On the other hand, it ensures sufficient adhesion between the inner surface 5 of the tire and the sound-absorbing element 6. Furthermore, unlike conventional methods such as polishing the inner surface of the tire, applying a film to the inner surface of the tire, or cleaning the inner surface of the tire, tire productivity is not negatively affected. As a result, both air retention and adhesion of the sound-absorbing element 6 can be achieved without negatively impacting tire productivity.

[0047] In particular, it is preferable that, in the process of forming a coating on the outer surface of the airbag, the coating covering time t (hour) and temperature T (°C) satisfy the conditions t ≥ -0.0571T + 9.14 and 10°C ≤ T ≤ 180°C. Furthermore, it is more preferable to set the temperature T to 90°C and the covering time t to 4 hours; even more preferably, it is preferable to set the temperature T to 150°C and the covering time t to 1 hour. By satisfying these conditions, the time for applying the release agent can be shortened in the coated airbag, and the shortening of the airbag's service life can be prevented. Here, a higher temperature T (°C) allows the coating to form in a shorter time, but the airbag is more prone to deterioration, shortening its service life.

[0048] Example

[0049] Tires were manufactured with a tire size of 275 / 35ZR20, in which sound-absorbing elements were fixed to the inner surface of the tread along the tire circumference via an adhesive layer. As shown in Table 1, the following tires were constructed: a method for removing the release agent, application of the release agent to the inner surface of the tire, use of an air bladder with a coating formed by the release agent during vulcanization, and the amount (by weight%) of the release agent (silicone) on the inner surface of the tire. These tires were compared with those of Examples 1 to 5 and Examples 1 to 3.

[0050] For Comparative Example 1, a release agent was applied to the inner surface of the tire, and no removal of the release agent was performed. However, for Comparative Examples 2-4, a release agent was applied to the inner surface of the tire, and the release agent was removed after the vulcanization process. Specifically, in Comparative Example 2, the release agent on the inner surface of the tire was removed by polishing; in Comparative Example 3, the release agent on the inner surface of the tire was removed by peeling off a film pre-applied to the inner surface of the tire; and in Comparative Example 4, the release agent on the inner surface of the tire was removed by cleaning the inner surface of the tire.

[0051] It should be noted that the amount of release agent (silicone) on the inner surface of the tire in Table 1 is the average of calculated values ​​based on measurements taken at four points along the tire circumference and three points along the tire width of each test tire after the manufacturing process using an energy-dispersive X-ray fluorescence analyzer (Shimadzu EDX-720). The measurement conditions were: vacuum, voltage 50 kV, current 100 µA, integration time 50 seconds, and collimator φ10 mm.

[0052] The adhesion, air retention, and tire productivity of the sound-absorbing components of these test tires were evaluated according to the following test methods, and the results are presented in Table 1.

[0053] Adhesion of sound-absorbing components:

[0054] The adhesion of the sound-absorbing component mentioned here refers to the evaluation of the peeling of the adhesive surface between the inner surface of the tire and the sound-absorbing component. Each test tire was assembled onto a wheel with a rim size of 20×9.5J. After a driving test using a rotary drum tester at a speed of 80 km / h, a tire pressure of 160 kPa, a load of 8.5 kN, and a driving distance of 6480 km, the presence or absence of sound-absorbing component detachment or peeling was visually confirmed. "◎" indicates no detachment or peeling of the sound-absorbing component; "○" indicates peeling of less than 1 / 8 of the entire sound-absorbing component; "Δ" indicates peeling of more than 1 / 8 but less than 1 / 4 of the entire sound-absorbing component; and "×" indicates peeling of more than 1 / 4 of the entire sound-absorbing component.

[0055] Air retention:

[0056] Each test tire was assembled onto a wheel with a rim size of 20×9.5J and placed under conditions of 270 kPa and 21°C for 24 hours. With an initial pressure of 250 kPa, the tires were then placed for 42 days. The pressure was measured, and the slope of the gas leakage from day 15 to day 42 was calculated. The evaluation results were expressed as the reciprocal of the measured values, with Comparative Example 1 set to 100. A higher index value indicates better air retention. It should be noted that an index value of 98 or higher indicates that the air retention performance remains at the previous level.

[0057] Tire productivity:

[0058] For each test tire, the manufacturing time (in minutes) required to produce one tire was measured. The evaluation results were expressed as the reciprocal of the measured value, with Comparative Example 1 set to 100. The higher the index value, the better the tire productivity.

[0059] [Table 1]

[0060]

[0061] According to Table 1, the pneumatic tires of Examples 1 to 3, compared with Comparative Example 1, do not worsen tire productivity, maintain air retention, and improve the adhesion of sound-absorbing components.

[0062] On the other hand, in Comparative Example 2, the inner surface of the tire was polished, which worsened tire productivity and reduced the thickness of the inner liner, thus deteriorating air retention. In Comparative Example 3, the film was adhered to the inner surface of the tire and then peeled off after vulcanization, which also worsened tire productivity. In Comparative Example 4, although the inner surface of the tire was cleaned, the release agent could not be completely removed, leaving a significant amount of release agent residue, which reduced the adhesion of the sound-absorbing component. In Comparative Example 5, the amount of release agent (silicone) on the inner surface of the tire was set too high, resulting in insufficient improvement in the adhesion of the sound-absorbing component.

[0063] Symbol Explanation

[0064] First pregnancy face

[0065] 2 side wall sections

[0066] 3rd tire bead

[0067] 4. Cavity

[0068] 5. Tire inner surface

[0069] 6 sound absorbing parts

[0070] 7 adhesive layers

[0071] 8 transfer layers

[0072] 9 missing parts

Claims

1. A pneumatic tire, vulcanized using an air bladder having a coating formed by a release agent, characterized in that, A sound-absorbing element is fixed to the inner surface of the tread along the tire circumference via an adhesive layer. The ratio of the amount of silicon in the release agent as detected by X-ray fluorescence analysis in at least the fixed area of ​​the sound-absorbing element, and the amount of silicon as measured by X-ray fluorescence analysis using sheet samples obtained from the tire carcass and inner liner as the test objects, is in the range of 0.1% to 10.0% by weight.

2. The pneumatic tire according to claim 1, characterized in that, The peel adhesion force of the adhesive layer is 5N / 20mm to 100N / 20mm.

3. The pneumatic tire according to claim 1 or 2, characterized in that, The adhesive layer is formed of double-sided adhesive tape, and the total thickness of the adhesive layer is 10µm to 150µm.

4. The pneumatic tire according to any one of claims 1 to 3, characterized in that, The adhesive layer is formed from double-sided tape containing only adhesive or double-sided tape containing both adhesive and non-woven fabric.

5. The pneumatic tire according to any one of claims 1 to 4, characterized in that, The center position of the sound-absorbing element in the width direction is configured within a range of ±10mm relative to the tire equator.

6. The pneumatic tire according to any one of claims 1 to 5, characterized in that, The volume of the sound-absorbing component is 10% to 30% of the inner volume of the tire.

7. The pneumatic tire according to any one of claims 1 to 6, characterized in that, The hardness of the sound-absorbing component is 80N to 150N, the tensile strength of the sound-absorbing component is above 90kPa, and the elongation at break of the sound-absorbing component is above 200%.

8. The pneumatic tire according to any one of claims 1 to 7, characterized in that, The sound-absorbing component has a missing portion at at least one location in the circumferential direction of the tire.

9. A method for manufacturing a pneumatic tire, comprising using an air bladder having a coating formed by a release agent to vulcanize a green tire, the method being characterized in that... When fixing a sound-absorbing component to the inner surface of the tread of a vulcanized pneumatic tire, the ratio of the amount of silicon in the release agent as detected by X-ray fluorescence analysis in at least the fixing area of ​​the sound-absorbing component, and the amount of silicon content as measured by X-ray fluorescence analysis using sheet samples obtained from the tire carcass and inner liner as the test objects, is in the range of 0.1% to 10.0% by weight. The sound-absorbing component is fixed in the fixing area of ​​the sound-absorbing component along the tire circumference via an adhesive layer.

10. The method for manufacturing a pneumatic tire according to claim 9, characterized in that, The peel adhesion force of the adhesive layer is 5N / 20mm to 100N / 20mm.

11. The method for manufacturing a pneumatic tire according to claim 9 or 10, characterized in that, The adhesive layer is formed of double-sided adhesive tape, and the total thickness of the adhesive layer is 10µm to 150µm.

12. The method for manufacturing a pneumatic tire according to any one of claims 9 to 11, characterized in that, The adhesive layer is formed from double-sided tape containing only adhesive or double-sided tape containing both adhesive and non-woven fabric.

13. The method for manufacturing a pneumatic tire according to any one of claims 9 to 12, characterized in that, The center position of the sound-absorbing element in the width direction is configured within a range of ±10mm relative to the tire equator.

14. The method for manufacturing a pneumatic tire according to any one of claims 9 to 13, characterized in that, The volume of the sound-absorbing component is 10% to 30% of the inner volume of the tire.

15. The method for manufacturing a pneumatic tire according to any one of claims 9 to 14, characterized in that, The hardness of the sound-absorbing component is 80N to 150N, the tensile strength of the sound-absorbing component is above 90kPa, and the elongation at break of the sound-absorbing component is above 200%.

16. The method for manufacturing a pneumatic tire according to any one of claims 9 to 15, characterized in that, The sound-absorbing component has a missing portion at at least one location in the circumferential direction of the tire.

Images