Self-sealing composition, self-sealing tire and method for manufacturing a self-sealing tire

Abstract

The present application relates to a kind of self-sealing composition, self-sealing tire and the manufacturing method of self-sealing tire.The self-sealing composition includes the following components by weight parts:50~100 parts natural rubber,0~50 parts polybutadiene rubber,40~70 parts high styrene resin,40~60 parts filling material,80~120 parts plasticizer,2~15 parts compatilizer,0~8 parts colorant;Compatilizer is selected to promote the compatilizer of high styrene resin and natural rubber;The number average molecular weight of natural rubber is (100~170) ×10 3 ;The number average molecular weight of polybutadiene rubber is (250~350) ×10 3 . By adjusting the formula, good crosslinking effect is realized in system, the crosslinking system in prior art can be saved, and the compatibility and aging resistance of self-sealing composition are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of tire manufacturing, and in particular relates to a self-sealing composition, a self-sealing tire and a method for manufacturing the self-sealing tire. Background Art

[0002] As the only part of a car that touches the ground, tires are inevitably susceptible to punctures from sharp objects like stones and nails, leading to leaks and even blowouts at high speeds. This presents a significant safety hazard in automotive use. Therefore, puncture-resistant, self-sealing tires have long been a research priority in the tire industry. Thanks to the concerted efforts of the industry, self-sealing tires have made significant progress.

[0003] Due to the puncture-resistant nature of self-sealing tires, when a foreign object pierces the tire during driving, the self-sealing rubber layer must be able to tightly wrap the foreign object to prevent tire leakage. When the foreign object is removed, the self-sealing rubber layer must immediately seal the tire leak. This requires the self-sealing rubber to possess certain special physical and chemical properties. On the one hand, the driving environment of the tire requires the self-sealing rubber to have a wide range of effective temperatures; on the other hand, the long life of the tire requires the self-sealing tire to have a sufficient effective time. To meet these requirements, existing literature and patents have disclosed the composition of existing self-sealing rubber compositions, which generally include butyl rubber or diene rubber, fillers, and additives such as vulcanizers, plasticizers, and crosslinking agents.

[0004] Existing self-sealing adhesives tend to flow inside the tire at high temperatures, while the sealant tends to harden and fall off at low temperatures. To address this problem, those skilled in the art typically increase the type and amount of cross-linking systems in their formulations to improve the stability of the self-sealing adhesives. Commonly used cross-linking systems include, but are not limited to, activators, vulcanizers, and cross-linking agents. However, increasing the cross-linking system can lead to poor aging resistance, significantly shortening the lifespan of self-sealing tires. Summary of the Invention

[0005] In response to the shortcomings in the related art, the present invention provides a self-sealing composition, a self-sealing tire and a method for manufacturing a self-sealing tire. By adjusting the formula, a good cross-linking effect is achieved, and the cross-linking system in the prior art can be omitted.

[0006] In a first aspect, the present application provides a self-sealing composition, comprising the following components, in parts by weight: 50-100 parts of natural rubber, 0-50 parts of polybutadiene rubber, 40-70 parts of high styrene resin, 40-60 parts of filler, 80-120 parts of plasticizer, 2-15 parts of compatibilizer, and 0-8 parts of colorant; the compatibilizer is an additive that can promote the compatibility of high styrene resin and natural rubber; the number average molecular weight of the natural rubber is (100-170)×10 3; The number average molecular weight of polybutadiene rubber is (250~350)×10 3 .

[0007] In some embodiments of the present application, the compatibilizer is a polystyrene-polyisoprene block copolymer.

[0008] In some embodiments of the present application, the high styrene resin is a copolymer of styrene and butadiene, and the styrene content in the high styrene resin is 70% to 90%.

[0009] In some embodiments of the present application, the filler material includes carbon black, white carbon black, or a combination of carbon black and white carbon black.

[0010] In some embodiments of the present application, the filling material further comprises an inorganic filler, and the weight ratio of the inorganic filler to carbon black, white carbon black, or a combination of carbon black and white carbon black is 1:(1-3).

[0011] In some embodiments of the present application, the plasticizer includes one or a combination of two or more of cycloalkanes, aromatic hydrocarbons, paraffin oils, dioctyl oxalate, dioctyl phthalate, and didecyl phthalate.

[0012] In some embodiments of the present application, the colorant includes one or a combination of two or more of carbon black, aniline black, and iron oxide black.

[0013] A second aspect of the present application provides a self-sealing tire, comprising a self-sealing layer prepared from any one of the above self-sealing compositions.

[0014] A third aspect of the present application provides a method for manufacturing a self-sealing tire, comprising the following steps:

[0015] Providing a finished tire, comprising a belt layer disposed inside the finished tire along a circumferential direction of the finished tire;

[0016] Prepare a self-sealing agent using the self-sealing composition as described above as a raw material;

[0017] The self-sealing agent and the organic solvent are mixed in a weight ratio of 1: (3-6) to prepare a slurry;

[0018] Applying rubber along the inner circumferential surface of the finished tire to form a rubber layer;

[0019] After the mortar layer is dried, the self-sealing agent is sprayed on the surface of the mortar layer to form a self-sealing layer;

[0020] After the self-sealing layer is dried, a self-sealing tire is obtained.

[0021] In some embodiments of the present application, the width of the mortar layer is 80% to 98% of the tire belt width, and the thickness is 0.2 to 0.5 mm; the width of the self-sealing layer is 75% to 95% of the tire belt width, and the thickness is 3 to 10 mm.

[0022] Compared with the prior art, the advantages and positive effects of the present invention are:

[0023] (1) The self-sealing composition provided in at least one embodiment of the present application achieves good cross-linking within the formulation system by adding a compatibilizer and limiting the number average molecular weight of the rubber system. Compared with existing formulations, the use of a cross-linking system is eliminated, thereby ensuring the compatibility and high-temperature aging resistance of the self-sealing composition.

[0024] (2) The self-sealing composition provided in at least one embodiment of the present application improves the processing properties of the rubber compound by adding a high-styrene resin. By limiting the styrene content in the high-styrene resin, the rubber compound prepared from the self-sealing composition has higher strength and better sealing properties.

[0025] (3) The self-sealing tire provided by at least one embodiment of the present application has excellent self-sealing properties. Because no cross-linking system is added, the tire's aging resistance is ensured, extending the service life of the self-sealing tire. Furthermore, during high-speed driving, the self-sealing layer remains firmly bonded to the tire's inner wall, preventing accumulation and wrinkling, and avoiding bulging, debonding, or flange displacement.

[0026] (4) The method for manufacturing a self-sealing tire provided in at least one embodiment of the present application provides a specially formulated adhesive that serves as a base layer formed between the self-sealing layer and the inner wall of the tire, achieving good adhesion between the two, eliminating the steps of cleaning and polishing the inner surface of the tire in the prior art, and effectively avoiding problems such as damage to the airtight layer due to excessive polishing of the tire, and the self-sealing layer falling off due to incomplete polishing of the release agent. DETAILED DESCRIPTION

[0027] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] A first aspect of an embodiment of the present application provides a self-sealing composition, comprising the following components, in parts by weight: 50 to 100 parts of natural rubber, 0 to 50 parts of polybutadiene rubber, 40 to 70 parts of high styrene resin, 40 to 60 parts of filler, 80 to 120 parts of plasticizer, 2 to 15 parts of compatibilizer, and 0 to 8 parts of colorant, wherein the compatibilizer is an auxiliary agent that can promote the compatibility of high styrene resin and natural rubber.

[0029] The self-sealing composition provided in the above embodiments of the present application achieves good cross-linking between the components by adding a compatibilizer and limiting the number average molecular weight of natural rubber and polybutadiene rubber. Compared with existing self-sealing formulas, the use of a cross-linking system is eliminated, the compatibility and high-temperature aging resistance of the self-sealing composition are fully guaranteed, and the service life of the self-sealing tire is extended.

[0030] The embodiments of the present application abandon the use of butyl rubber in the self-sealing composition in the prior art and increase the use of natural rubber. Those skilled in the art can adjust the amount of natural rubber added within the above range according to actual needs. For example, it can also be 60, 70, 80, 90, etc. and any value within the above range.

[0031] After omitting the use of cross-linking system, in order to improve the self-sealing effect of self-sealing composition, the number average molecular weight of natural rubber is controlled. If the number average molecular weight of natural rubber is too high, Mooney viscosity will be caused to be high, processing characteristics will be adversely affected, and plasticity retention (PRI) will be caused to reduce. PRI is an antioxidant index, which reflects the ratio of the rapid plasticity value (P30) of the natural rubber after heat aging to the rapid plasticity value (P0) of the unaged sample. PRI reduces the antioxidant variation representing natural rubber, causes the fluidity of the self-sealing agent prepared by this self-sealing composition to increase at high temperatures, and affects the sealing effect of self-sealing agent. If the number average molecular weight of natural rubber is too low, too low Mooney viscosity and too high PRI will be caused, processing characteristics and the sealing performance of self-sealing agent will be adversely affected equally.

[0032] Based on the above, the present invention limits the number average molecular weight of natural rubber to (100-170)×10 3 The natural rubber with a number average molecular weight within the above range can simultaneously meet the processing performance and antioxidant properties required to achieve the self-sealing effect, and can form a good cross-linking effect with other components. Those skilled in the art can adjust the above range according to actual production conditions and needs. For example, it can also be 120×10 3 , 130×10 3 , 140×10 3 , 150×10 3, 160×10 3 etc. and any value within the above range.

[0033] In some embodiments, polybutadiene rubber is used in combination with natural rubber. Both polybutadiene rubber and natural rubber are non-polar rubbers with good compatibility. When blended, they form a sea-island phase structure. Those skilled in the art can adjust the amount of polybutadiene rubber within the aforementioned range based on practical needs. For example, the amount can be 20, 30, 40, or any other value within the aforementioned range.

[0034] At the interface between polybutadiene rubber and natural rubber lies an interfacial layer, a product of the interpenetration and diffusion of the two rubber molecular segments. It is shared by both phases. When an external force acts on the two-phase blend, the force in the sea phase is transmitted to the island phase through this interfacial layer. The island phase particles deform under the force and then transmit the force to the sea phase through this interfacial layer. Therefore, the properties of this interfacial layer significantly influence the bond strength and interfacial stability between the polybutadiene rubber and natural rubber molecules. Generally, a thicker interfacial layer results in a more stable interfacial structure, which promotes crosslinking between the phases and results in a more stable blend.

[0035] The number-average molecular weight of polybutadiene rubber significantly influences the thickness of the interfacial layer between it and natural rubber. A low molecular weight results in a thicker interfacial layer, improving compatibility with natural rubber. However, excessive compatibility can increase the fluidity of the self-sealing adhesive, causing it to flow at high temperatures, impairing its self-sealing performance. A high molecular weight results in a thinner interfacial layer, impairing compatibility with natural rubber and affecting the stability of the blended rubber.

[0036] In the examples of the present application, a large number of tests were conducted to balance compatibility and fluidity according to the requirements of self-sealing. Finally, the number average molecular weight of polybutadiene rubber was limited to (250-350)×10 3 Within this range, polybutadiene rubber can be well blended with natural rubber and its fluidity can meet the requirements of self-sealing effect. Those skilled in the art can adjust the above range according to actual needs. For example, it can also be 280×10 3 , 300×10 3 , 320×10 3 etc. and any value within the above range.

[0037] The embodiments of the present application limit the number average molecular weight of natural rubber and polybutadiene rubber in the self-sealing composition and use a compatibilizer. Even without adding a cross-linking system, a good cross-linking effect can still be formed in the formula system, so that the self-sealing composition does not flow at high temperatures and does not harden at low temperatures, thereby achieving a good self-sealing effect.

[0038] Since the present application adds polybutadiene rubber and a large amount of filling materials, the processing properties of the rubber compound will be affected. Therefore, the addition of high styrene resin to the self-sealing composition of the present application can improve the Mooney scorch performance and significantly improve the processing properties of the rubber compound. In order to match the other components in the self-sealing composition and improve the processing properties to the greatest extent, the addition amount of high styrene resin is 40 to 70 parts. It is understood that those skilled in the art can make adjustments within the above range according to actual conditions. For example, it can also be 45, 50, 55, 60, 65, etc. and any value within the above range.

[0039] The high-styrene resin described in this application is a copolymer of styrene and butadiene. Generally, a high-styrene resin is one with a styrene content of 70% or more. When the styrene content of a high-styrene resin is approximately 70%, the resin softens at approximately 55°C. When the styrene content is 85% to 90%, the resin softens at 90°C to 100°C. When high-styrene resins are used in rubber, increasing the styrene content improves the hardness, strength, and stiffness of the rubber.

[0040] In some embodiments, the styrene content in the high styrene resin is 70% to 90%. After adding a high styrene resin with a styrene content within this range, the self-sealing adhesive made from the self-sealing composition has a higher strength. When a sharp object punctures the tire, the self-sealing adhesive can tightly wrap the sharp object, thereby improving the self-sealing effect. In addition, limiting the styrene content to this range can also avoid a decrease in elasticity due to excessive strength of the self-sealing composition. The styrene content in the high styrene resin can also be 75%, 80%, 85%, etc., as well as any value within the above range. Those skilled in the art can adjust it according to actual needs.

[0041] In the self-sealing composition provided in the embodiment of the present application, although the blending effect of high styrene resin and natural rubber is good, due to the large amount of high styrene resin added, its compatibility with natural rubber will be affected to a certain extent. In order to promote the compatibility of high styrene resin and natural rubber, a compatibilizer is added to the self-sealing composition. In the embodiment of the present application, according to the amount of high styrene resin added, the amount of compatibilizer added is limited to within the range of 2 to 15 parts. It is understood that those skilled in the art can adjust within the above range according to actual needs. For example, it can also be 3, 5, 7, 10, 12, etc. and any value within the above range.

[0042] Since the main component of natural rubber is polyisoprene rubber, the compatibilizer is selected to be an additive that can promote the compatibility of high styrene resin and polyisoprene rubber. The compatibilizer can be enriched at the interface between high styrene resin and polyisoprene rubber, improving the interfacial tension and adhesion, thereby improving the compatibility between the two.

[0043] In some embodiments, the compatibilizer is a polystyrene-polyisoprene block copolymer. The block copolymer has two polymer segments, which can achieve good compatibility.

[0044] The self-sealing composition provided in the embodiments of the present application also includes 40 to 60 parts of a filler material, wherein the filler material includes carbon black, white carbon black, or a combination of carbon black and white carbon black. Alternatively, carbon black or white carbon black can be used alone as the filler material. In some embodiments, when carbon black is used alone as the filler material, the average particle size of the selected carbon black is within the range of 49 to 60 nm, that is, N660 carbon black that meets the ASTM standard can be selected.

[0045] In some embodiments, the filler material further comprises an inorganic filler, and the weight ratio of the inorganic filler to carbon black, white carbon black, or a combination of carbon black and white carbon black is 1:(1-3). The inorganic filler includes one or a combination of two or more of carbonates, silicates, sulfates, and metal oxides. The above ratio can be adjusted according to actual needs, for example, it can be 1:1, 1:2, or 1:3, etc., and those skilled in the art can select according to actual needs.

[0046] The self-sealing composition provided in the embodiments of the present application further comprises 80 to 120 parts of a plasticizer. In some embodiments, the plasticizer comprises one or a combination of two or more of cycloalkanes, aromatic hydrocarbons, paraffin oil (paraffin oil), dioctyl oxalate (DOA), dioctyl phthalate (DOP), and didecyl phthalate (DDP).

[0047] In some embodiments, a plasticizer with a weak polarity is selected so as to have good compatibility with the raw rubber system in the self-sealing composition. In addition, the number average molecular weight of the plasticizer is limited to (0.5 to 10) × 10 3 The plasticizer can be selected from one or a combination of two or more of naphthenic oil, environmentally friendly aromatic oil (TDAE oil), aromatic oil (DAE oil), paraffin oil, and vegetable oil.

[0048] The self-sealing composition provided in the embodiments of the present application further comprises 0 to 8 parts of a colorant. In some embodiments, the colorant comprises one or a combination of two or more of carbon black, aniline black, and black iron oxide.

[0049] A second aspect of the present invention provides a self-sealing tire, comprising a self-sealing layer made from the self-sealing composition according to any of the above embodiments. Typically, the self-sealing layer is applied along the inner circumference of the tire.

[0050] The self-sealing tires provided in the above embodiments of the present application feature a self-sealing layer made from a self-sealing composition that exhibits high viscosity, high elasticity, and high sealing properties. This ensures that even if the airtight layer is punctured by a sharp object during normal driving, the self-sealing layer can still provide a seal and protection against the puncture. Furthermore, because the self-sealing layer rubber compound has good compatibility and lacks a cross-linking system, the self-sealing tire exhibits excellent aging resistance, extending the service life of the self-sealing tire.

[0051] In the manufacturing process of self-sealing tires, there are usually two methods for forming the self-sealing layer: one is to spray a rubber compound with a self-sealing effect onto the inner wall of the tire in the form of spraying after the tire is vulcanized and formed to form a self-sealing layer; the other is to stick the prepared self-sealing film on the tire carcass to form a self-sealing layer during the tire vulcanization and forming. However, these methods all have the problem of unstable adhesion between the self-sealing layer and the tire. The current treatment method is to clean and polish the inner surface of the tire before spraying or patching, and clean the oil stains of the isolation agent on the inner surface of the tire. If the cleaning or polishing is not in place, the self-sealing layer will fall off, flanging, shift, and rubber accumulation during the driving of the tire; and excessive polishing will damage the tire's airtight layer, causing the tire to leak slowly, posing a great hidden danger to driving safety.

[0052] To solve the above problems, a third aspect of the embodiments of the present application provides a method for manufacturing a self-sealing tire, the method comprising the following steps:

[0053] S1. Providing a finished tire, comprising a belt layer disposed within the finished tire along a circumferential direction of the finished tire. The structure of the tire may refer to the prior art and will not be described in detail in this application.

[0054] S2. preparing a self-sealing agent using the self-sealing composition provided in any one of the above embodiments as a raw material;

[0055] S3, mixing the self-sealing agent and the organic solvent in a weight ratio of 1: (3-6) to prepare a slurry;

[0056] S4. Applying rubber along the inner circumferential surface of the tire to form a rubber layer;

[0057] S5, after the mortar layer is dried, spraying the self-sealing agent on the surface of the mortar layer to form a self-sealing layer;

[0058] S6. After the self-sealing layer is dried, a self-sealing tire is obtained.

[0059] In the method for manufacturing the self-sealing tire of the above embodiment, a specially formulated slurry is provided. The slurry is made from the above-mentioned self-sealing composition in combination with an organic solvent. Before spraying the self-sealing agent, the slurry is applied to the inner circumferential surface of the tire, which can effectively bond the inner surface of the tire and the sealant, eliminating the steps of cleaning and polishing the inner surface of the tire in the prior art, and effectively avoiding problems such as damage to the airtight layer due to excessive polishing of the tire, and the self-sealing layer falling off due to incomplete polishing of the release agent. The self-sealing tire prepared using the above preparation method can maintain a strong bond between the self-sealing layer and the inner wall of the tire even when the tire is running at high speed, without accumulation and wrinkling, and without problems such as bulging, degumming, and flange displacement.

[0060] In the above preparation method, the mortar is prepared by mixing a self-sealing agent and an organic solvent in a ratio of 1:3-6. This mortar exhibits good adhesion to both the tire inner wall and the self-sealing layer. It is understood that the ratio of the self-sealing agent to the organic solvent in the mortar can also be 1:4, 1:5, or any other value within the above range. In some embodiments, the organic solvent includes gasoline or a benzene-based solvent. Optionally, the organic solvent is 120# gasoline.

[0061] In some embodiments, the width of the adhesive layer is 80% to 98% of the tire belt width. The adhesive layer in this width range can basically cover the width of the tire in contact with the ground during driving, thereby providing sufficient spraying area for the self-sealing layer.

[0062] In some embodiments, the thickness of the adhesive layer is 0.2-0.5 mm. The adhesive layer within this thickness range can form a tight adhesion with the inner wall of the tire and the self-sealing layer.

[0063] In some embodiments, the width of the self-sealing layer is 75% to 95% of the width of the tire belt layer. This width range can cover the width of the tire in contact with the ground during driving. The thickness of the self-sealing layer is 3 to 10 mm. A self-sealing layer with this thickness can play a good self-sealing role.

[0064] In some embodiments, the method for preparing the self-sealing agent comprises the following steps:

[0065] S21, mixing 50-100 parts of natural rubber, 0-50 parts of polybutadiene rubber, and 40-70 parts of high styrene resin in an internal mixer to 145° C. and discharging the mixed rubber;

[0066] S22, the rubber mixture is left to stand for 4 hours;

[0067] S23, mixing the rubber mixture with 40-60 parts of filler, 80-120 parts of plasticizer, 2-15 parts of compatibilizer and 0-8 parts of colorant in an internal mixer for 800 seconds and then discharging to complete the preparation of the self-sealing agent.

[0068] In some embodiments, during the process of forming the slurry in step S3, after the self-sealing agent and the organic solvent are mixed, the process further includes stirring until the sealant is completely dissolved, and filtering out impurities using a filter.

[0069] In order to more clearly and in detail introduce the self-sealing composition and the self-sealing tire provided by the embodiments of the present invention, they will be described below in conjunction with specific embodiments.

[0070] The components of Examples 1-14 and Comparative Examples 1-7 are shown in Table 1.

[0071] Table 1 Comparative Table of Components of Examples 1-14 and Comparative Examples 1-7

[0072]

[0073] Performance Testing

[0074] 1. High temperature fluidity test

[0075] The sealants prepared in Examples 1-9 and Comparative Examples 1-7 were subjected to a fluidity test at a high temperature of 100° C. The specific experimental method is as follows:

[0076] 10g of sealant was applied to cardboard and placed vertically in a 100°C oven. The initial length was marked as 0cm. The length was measured and recorded at regular intervals to indicate the sealant's high-temperature fluidity. The test results are shown in Table 2.

[0077] Table 2 High temperature fluidity test results

[0078]

[0079] The test results in Table 2 above are analyzed as follows:

[0080] It can be seen from the test results of Examples 1 to 9 that the self-sealing agent prepared from the self-sealing composition provided in the examples of the present application does not flow at high temperatures (100° C.), and its fluidity can meet the requirements for achieving a self-sealing effect during driving.

[0081] In Comparative Example 1, the self-sealing compound prepared without the addition of either a compatibilizer or a crosslinker exhibited significant flow at high temperatures, reaching a length of 46.2 cm after 1 hour and 129 cm after 2 hours. Due to the excessive flow distance, exceeding the length of the cardboard, subsequent measurements were not performed. The self-sealing compound prepared in Comparative Example 2 exhibited poor processing properties, with difficulty in mixing and molding during the preparation process, leading to preparation failure, which was attributed to the excessive addition of a compatibilizer. Comparative Example 3, which did not include a compatibilizer but did include an active agent as a crosslinking agent, exhibited better flowability, but this would have adversely affected the subsequent aging resistance of the tire.

[0082] Analysis of Examples 1 to 3 and Comparative Examples 4 and 5 shows that when the number average molecular weight of natural rubber is limited to (100 to 170)×10 3 When the number average molecular weight of the natural rubber is within this range, the fluidity of the self-sealing agent prepared from the self-sealing composition can meet the requirements of the self-sealing effect. However, when the number average molecular weight of the natural rubber exceeds this range, the self-sealing agent does not form a good cross-linking effect, its fluidity increases, and is not conducive to achieving the self-sealing effect.

[0083] Analysis of Examples 7 to 8 and Comparative Examples 6 and 7 shows that when polybutadiene rubber is added to the self-sealing composition, and the number average molecular weight of the polybutadiene rubber is limited to (250 to 350)×10 3 When the number average molecular weight of polybutadiene rubber is within the above range, the compatibility of polybutadiene rubber and natural rubber can meet the fluidity requirements for achieving a self-sealing effect and achieve good blending performance. However, when the number average molecular weight of polybutadiene rubber exceeds the above range, the fluidity of the self-sealing agent at high temperatures increases, which is not conducive to achieving a self-sealing effect.

[0084] 2. Rolling resistance test

[0085] Tires with a specification of 215 / 55R17 produced by our company were selected for testing. A self-sealing agent was prepared from a self-sealing composition, and the self-sealing agent was mixed with 120# gasoline in a weight ratio of 1:5 to form a slurry, which was then applied to the inner circumferential surface of the tire. The spraying width of the slurry was 95% of the width of the tire belt layer, and the thickness was 0.38 mm; after the slurry layer was dried, the self-sealing agent was sprayed on the surface of the slurry layer to form a sealing layer. The width of the sealing layer was 92% of the width of the belt layer, and the thickness was 4.8 mm. Self-sealing tires were manufactured according to the self-sealing compositions provided in Example 2, Example 8, Comparative Example 3, Comparative Example 5, and Comparative Example 7 according to the above method, and were denoted as A1, A2, A3, A4, and A5, respectively.

[0086] Rolling resistance tests were conducted in accordance with the international standard ISO 28580-2018, including both before and after sealant application. Self-sealing tires were tested at high speeds in accordance with GB / T 4502-2016 on a high-speed tire durability testing machine. The tires were fully heated and then retested after cooling. The rolling resistance results are shown in Table 3 below.

[0087] Table 3 Rolling resistance test results

[0088] serial number A1 A2 A3 A4 A5 Before applying sealant 6.28 6.20 6.16 6.28 6.22 After applying sealant 6.28 6.23 6.19 6.29 6.22 After heat generation 6.29 6.23 6.73 6.33 6.36

[0089] The rolling resistance test results in Table 3 show that the self-sealing tires manufactured according to Examples 2 and 8 of the present application did not experience a significant impact on rolling resistance due to the application of the self-sealing agent. However, the self-sealing tires manufactured according to Comparative Examples 3, 5, and 7 experienced a significant increase in rolling resistance after heating, which was detrimental to the tire's energy conservation and environmental performance.

[0090] 3. Static air tightness test

[0091] A tire with a specification of 215 / 55R17 produced by our company was selected for the test. A self-sealing agent was prepared according to the self-sealing composition of Examples 10 to 14. The self-sealing agent was mixed with 120# gasoline at a weight ratio of 1:5 to form a slurry, and the slurry was applied to the inner circumferential surface of the tire. The spraying width of the slurry was 85% of the width of the tire belt layer, and the thickness was 0.35mm; after the slurry layer was dried, the self-sealing agent was sprayed on the surface of the slurry layer to form a sealing layer. The width of the sealing layer was 80% of the width of the belt layer, and the thickness was 5.5mm. The self-sealing tires manufactured according to the self-sealing compositions provided in Examples 10 to 14 were denoted as B1, B2, B3, B4, and B5, respectively.

[0092] According to GB / T 38510-2020, a static airtightness performance test was conducted on the self-sealing tire at room temperature to evaluate its airtightness. The evaluation results are shown in Table 4.

[0093] Table 4 Static air tightness test results

[0094]

[0095] According to the results in Table 4, the airtightness of tires B2 to B4 is better than that of tires B1 and B5. In other words, when the styrene content in the high styrene resin is in the range of 70% to 90%, the self-sealing properties of the self-sealing tires obtained are significantly improved.

[0096] 4. Evaluation of the uniformity and self-sealing performance of self-sealing tires

[0097] Self-sealing tires C1 to C4 were manufactured according to the parameters in Table 5.

[0098] Table 5 Related parameters of Example 15-Example 18

[0099]

[0100]

[0101] Comparative Example

[0102] Four 215 / 55R17 self-sealing tires of a certain brand were purchased from the market and were labeled D1, D2, D3, and D4.

[0103] Uniformity tests were conducted on tires C1-C4 and D1-D4 in accordance with the national standard GB / T 18506-2013. The tires' RFV values ​​were measured. The RFV value for tire C1 was denoted as 1, and the other tires were represented by corresponding indices. A higher index indicates worse uniformity, while a lower index indicates better uniformity. The results of the uniformity tests are shown in Table 6.

[0104] Table 6 Tire uniformity test results

[0105]

[0106] It can be seen from the uniformity test results in Table 6 that the self-sealing tires manufactured according to Examples 15 to 18 of the present application have better uniformity than commercially available self-sealing tires when the sealing layer thickness is similar.

[0107] The self-sealing performance of the self-sealing tire was evaluated in accordance with GB / T 38510-2020. The evaluation results are shown in Table 7.

[0108] Table 7 Self-sealing performance test results

[0109]

[0110]

[0111] The self-sealing test results in Table 7 show that, compared to existing commercially available self-sealing tires, the self-sealing tires manufactured according to Examples 15 to 18 of the present application exhibit superior sealing properties under various operating conditions. In particular, C1 exhibits zero air pressure loss after nail removal, maintaining excellent sealing properties. These results demonstrate that the sealing layer provided by the examples of the present application can tightly wrap around sharp objects such as nails piercing the tire and quickly seal the puncture site after nail removal, ensuring vehicle safety.

Claims

1. A self-sealing composition, characterized in that The invention comprises the following components in parts by weight: 50 to 100 parts of natural rubber, 0 to 50 parts of polybutadiene rubber, 40 to 70 parts of high styrene resin, 40 to 60 parts of filler, 80 to 120 parts of plasticizer, 2 to 15 parts of compatibilizer, and 0 to 8 parts of colorant; the compatibilizer is an auxiliary agent that can promote the compatibility of the high styrene resin and the natural rubber; the number average molecular weight of the natural rubber is (100 to 170)×10 3 The number average molecular weight of the polybutadiene rubber is (250-350)×10 3 The high styrene resin is a copolymer of styrene and butadiene, and the styrene content in the high styrene resin is 70% to 90%; the self-sealing composition does not include a cross-linking system.

2. The self-sealing composition according to claim 1, characterized in that The compatibilizer is a polystyrene-polyisoprene block copolymer.

3. The self-sealing composition according to claim 1, characterized in that The filler material includes carbon black, white carbon black or a combination of carbon black and white carbon black.

4. The self-sealing composition according to claim 3, characterized in that The filling material further includes an inorganic filler, and the weight ratio of the inorganic filler to the carbon black, the white carbon black, or the combination of the carbon black and the white carbon black is 1:(1-3).

5. The self-sealing composition according to claim 1, characterized in that The plasticizer includes one or a combination of two or more of cycloalkanes, aromatic hydrocarbons, paraffin oil, dioctyl oxalate, dioctyl phthalate, and didecyl phthalate.

6. The self-sealing composition according to claim 1, characterized in that The colorant includes one or a combination of two or more of carbon black, aniline black, and iron oxide black.

7. A self-sealing tire, characterized in that: The invention comprises a self-sealing layer prepared from the self-sealing composition according to any one of claims 1 to 6.

8. A method for manufacturing a self-sealing tire, characterized in that: The following steps are involved: Providing a finished tire, comprising a belt layer disposed inside the finished tire along a circumferential direction of the finished tire; Preparing a self-sealing agent using the self-sealing composition according to any one of claims 1 to 6 as a raw material; The self-sealing agent and the organic solvent are mixed in a weight ratio of 1: (3-6) to prepare a slurry; Applying the rubber along the inner circumferential surface of the finished tire to form a rubber layer; After the mortar layer is dried, spraying the self-sealing agent on the surface of the mortar layer to form a self-sealing layer; After the self-sealing layer is dried, the self-sealing tire is obtained.

9. The method for manufacturing a self-sealing tire according to claim 8, wherein: The width of the mortar layer is 80% to 98% of the width of the tire belt layer, and the thickness is 0.2 to 0.5 mm; the width of the self-sealing layer is 75% to 95% of the width of the tire belt layer, and the thickness is 3 to 10 mm.

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