Self-repairing tire inner liner composite material as well as preparation method and application thereof

Abstract

The invention discloses a self-repairing tire inner liner composite material and a preparation method and application thereof, and belongs to the technical field of tire inner liner materials. The material comprises: 10-50 parts of epoxidized natural rubber; 50 to 100 parts of epoxidized iron-series butadiene-isoprene rubber; 0.5-2 parts of a metal salt; 1-3 parts of dicarboxylic acid; 20 to 80 parts of reinforcing filler; 10-30 parts of a plasticizer; 1-5 parts of zinc oxide; 0.5 to 3 parts of stearic acid; 0.1 to 3 parts of sulfur; 0.1 to 2 parts of an accelerant; 0.1 to 1 part of an imidazole catalyst; the number-average molecular weight of the epoxidized-oxide-series butadiene-isoprene rubber is 30-90 w, and the epoxidation degree of the epoxidized-oxide-series butadiene-isoprene rubber is 10-30%; the metal salt is one or more of ferric salt, aluminum salt and copper salt. According to the preparation method, the epoxidized natural rubber and the epoxidized-iron-series combed butadiene-isoprene rubber are blended, then the metal salt, the dicarboxylic acid and the sulfur are matched to serve as cross-linking agents, the composite material for the tire inner liner with excellent self-repairing performance and air tightness is prepared, and compared with a tire inner liner material in the prior art, the composite material has obvious performance advantages, and the service life of the tire inner liner is prolonged. The comprehensive performance of the tire can be improved.

Description

Technical Field

[0001] The present application relates to a self-healing tire airtight layer composite material, a preparation method thereof, and an application thereof, belonging to the technical field of tire airtight layer materials. Background Art

[0002] With the continuous development of the automotive industry, people are increasingly concerned about the performance of automobiles. As the only medium for an automobile to contact the ground, during the dynamic movement process, the tire performance will directly affect the comfort and safety of the vehicle driving. At the same time, as an auto parts consumable, its own performance will also affect the service life and fuel economy of the vehicle.

[0003] Since the invention of the tire, after several reforms, vacuum radial tires have gradually replaced the old-fashioned inner tube tires. Vacuum tires have more excellent safety (certain self-sealing ability for punctures), improved wear resistance (the tire is in direct contact with the wheel hub, with better heat dissipation, improving wear resistance), better fuel economy (able to maintain good driving stability and small friction, which is beneficial for shock absorption and increasing vehicle speed), and a more comfortable driving experience (the tire is sealed integrally with the wheel rim, with high manufacturing precision, high positioning between tires, and small radial runout of the wheel).

[0004] For a vacuum tire to be a container for gas, it is necessary to ensure excellent airtightness to guarantee the use stability of the tire. Butyl rubber has rich side groups and a unique spatial helical structure, which can isolate the passage of gas between molecular chains. Its airtightness is about 10 times that of natural rubber, and it is an ideal main rubber material for the airtight layer.

[0005] Although butyl rubber has excellent airtightness, when applied to rubber composites, due to its low content of unsaturated chemical bonds, its vulcanization speed is slow, its processing performance is poor, and its adhesiveness and mutual adhesiveness need to be improved. In addition, when butyl rubber is used as an airtight layer material, there are also problems such as poor flexibility and large hysteresis deformation, resulting in high dynamic heat generation.

[0006] Patent CN116285135A provides a rubber composite material with both high airtightness and tear resistance, a preparation method thereof, and an application thereof. Iron-based comb-branched butyl-pentyl rubber with the same high side group content is introduced into butyl rubber to improve its vulcanization processing performance and flexibility. However, due to the same high side group content of this material, the problem of high dynamic heat generation still exists; at the same time, since this material does not have self-healing properties during actual use, once the tire airtight layer is punctured by a sharp object, its airtightness will permanently decrease, and there is no other way but to repair the airtight layer.

[0007] Patent CN118006051A also provides a rubber composition for a tire inner liner and its preparation method. However, its tensile strength, modulus at a specified elongation, and airtightness still need to be improved, and it also does not have self-healing properties.

[0008] Therefore, developing a tire inner liner material with excellent airtightness and self-healing properties is of great significance for the manufacture of high-performance tires. Summary of the Invention

[0009] To solve the above problems, a self-healing tire inner liner composite material, its preparation method, and application are provided. By blending and compounding epoxidized natural rubber with epoxidized iron-based comb-branched butadiene-pentadiene rubber, the dynamic heat generation is reduced without sacrificing the airtightness of the material. Secondly, by adding metal salts and dicarboxylic acids that can react with epoxy groups, metal-epoxy group coordination bonds and β-hydroxyester bonds are formed inside the material. These metal coordination bonds and dynamic covalent bonds endow the material with rapid self-healing properties, and the properties of the material after repair are not attenuated compared with the raw material. The tire inner liner composite material provided by the solution of this application has obvious performance advantages compared with the products in the prior art, can improve the comprehensive performance of the tire, and has important market application potential.

[0010] This application provides a self-healing tire inner liner composite material. By weight, the tire inner liner composite material includes: 10-50 parts of epoxidized natural rubber; 50-100 parts of epoxidized iron-based comb-branched butadiene-pentadiene rubber; 0.5-2 parts of metal salt; 1-3 parts of dicarboxylic acid; 20-80 parts of reinforcing filler; 10-30 parts of plasticizer; 1-5 parts of zinc oxide; 0.5-3 parts of stearic acid; 0.1-3 parts of sulfur; 0.1-2 parts of accelerator; 0.1-1 part of imidazole catalyst; The molecular weight of the epoxidized iron-based comb-branched butadiene-pentadiene rubber is 300,000-900,000, and the epoxidation degree is 10%-30%; the metal salt is one or more of iron salts, aluminum salts, and copper salts.

[0011] The present application provides a self-healing tire airtight layer composite material, in which metal ions in the metal salt can form coordination bonds with epoxy groups in the rubber. These coordination bonds belong to non-covalent bonds. After being damaged by external forces, they can absorb part of the energy and have a fast re-bonding speed, accelerating the self-healing speed. When combined with dicarboxylic acid, it forms β-hydroxyester bonds with epoxy groups in the rubber, which belong to dynamic covalent bonds. The self-healing speed is slower but the bond energy is larger, enabling the repaired material to regain high strength, so that the airtight layer composite material has both excellent self-healing performance and airtight performance.

[0012] In the solution of the present application, iron oxide-based comb-shaped butadiene-pentene rubber and epoxidized natural rubber are selected for combination. The iron oxide-based comb-shaped butadiene-pentene rubber has a chemical structure similar to that of butyl rubber, such as a relatively high side group content and excellent airtightness. And after epoxidation, the intermolecular interaction is closer, the airtightness is further improved, and the combination with the belt layer is closer. The epoxy groups in the iron oxide-based comb-shaped butadiene-pentene rubber and epoxidized natural rubber provide active sites, providing a basis for the material to achieve self-healing function. They cooperate synergistically with metal salts and dicarboxylic acids, making it have obvious performance advantages compared with the tire airtight layer materials in the prior art and capable of improving the comprehensive performance of the tire.

[0013] Optionally, the iron oxide-based comb-shaped butadiene-pentene rubber is obtained by epoxidation modification of iron-based comb-shaped butadiene-pentene rubber with one or more of hydrogen peroxide, performic acid or peracetic acid. The degree of epoxidation represents the proportion of original carbon-carbon double bonds converted into epoxy groups on the rubber molecular chain.

[0014] Optionally, the iron oxide-based comb-shaped butadiene-pentene rubber is a gel-free iron oxide-based comb-shaped butadiene-pentene rubber. If gel appears during the epoxidation process, the iron-based comb-shaped butadiene-pentene rubber undergoes premature crosslinking, which has an adverse effect on subsequent properties.

[0015] Optionally, the iron-based comb-shaped butadiene-pentene rubber is composed of random copolymerization of isoprene and butadiene, and the side group content is 60-80%.

[0016] Optionally, the iron-based comb-shaped butadiene-pentene rubber is composed of random copolymerization of isoprene and butadiene, and the molar ratio of butadiene to isoprene is 1:(1-10).

[0017] Optionally, the iron-based comb-shaped butadiene-pentene rubber is composed of random copolymerization of isoprene and butadiene, and the molar ratio of butadiene to isoprene is 1:(3-10). A higher isoprene content will be better for improving airtightness.

[0018] Among them, isoprene includes 3,4-isoprene and 1,4-isoprene, and butadiene includes 1,2-butadiene and 1,4-butadiene.

[0019] Optionally, the molar content of 1,2-butadiene in the butadiene is 60-80%; Optionally, the molar content of 3,4-isoprene in the isoprene is 60-80%.

[0020] In this application, the iron-based comb-branched butyl-pentene rubber with specific properties is selected as the raw material for preparing the epoxidized iron-based comb-branched butyl-pentene rubber mainly for the following reasons: (1) This structure of butyl-pentene rubber has a higher side group content and a smaller free volume between molecular chains, which hinders the diffusion of gas molecules inside the material. Therefore, when used as an airtight layer material, better airtightness can be obtained; (2) This structure of butyl-pentene rubber has more side group double bonds than butyl rubber, so it has a faster vulcanization speed and is convenient for processing and molding; (3) During the epoxidation process of this structure of butyl-pentene rubber, the molecular main chain is less damaged, and the high molecular weight of the rubber and its excellent properties can be retained to the greatest extent.

[0021] Optionally, the epoxidation degree of the epoxidized natural rubber is 20-40%. The epoxidized natural rubber mainly plays a reinforcing role in the system of this application. After the epoxidation treatment of natural rubber, the compatibility with the epoxidized iron-based comb-branched butyl-pentene rubber is improved. However, if the epoxidation degree is too high, the elasticity of the rubber will be lost. By controlling the epoxidation degree within the above range, while ensuring the strength of the epoxidized iron-based comb-branched butyl-pentene rubber, the system compatibility is better and its elastic properties can also be guaranteed.

[0022] Optionally, the dicarboxylic acid is one or more of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, methylmalonic acid, 2-methylsuccinic acid, 2-methylglutaric acid, 2,2,3,3-tetramethylsuccinic acid, 1,4-cyclohexanedicarboxylic acid, 2,2-dimethyl-3-carboxycyclobutaneacetic acid, 1,2,2-trimethylcyclopentane-1,3-dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, o-biphenyldicarboxylic acid, o-diphenyletherdicarboxylic acid and p-diphenyletherdicarboxylic acid.

[0023] Optionally, the dicarboxylic acid is one or more of pimelic acid, suberic acid, azelaic acid, sebacic acid. Selecting the above long-chain carboxylic acid molecules, their structures are more flexible, which is more conducive to improving the toughness of the airtight layer composite material.

[0024] Optionally, the dicarboxylic acid is suberic acid or sebacic acid. Selecting the above long-chain carboxylic acid molecules, the prepared airtight layer material has better comprehensive properties.

[0025] Optionally, the metal salt is one or more of ferric chloride, aluminum chloride, cupric chloride.

[0026] Optionally, the metal salt includes one or both of ferric chloride and aluminum chloride. By selecting the above trivalent metal salt, the metal ion has a higher charge density, resulting in a stronger electrostatic attraction between it and the oxygen atom with partial negative charge in the epoxy group. The formed coordination bond is more stable, has a greater bond energy, and better self-healing performance.

[0027] Optionally, the reinforcing filler is one or more of carbon black N110, N219, N220, N231, N234, N326, and N330; Optionally, the plasticizer is one or more of aromatic oil, naphthenic oil, paraffin oil, DOP, and DBP; Optionally, the accelerator is a sulfenamide accelerator. In the system of the present application's solution, it has good scorch resistance.

[0028] Optionally, the sulfenamide accelerator is one or both of accelerator CZ and accelerator NS.

[0029] Optionally, the imidazole catalyst is one or both of 1-methylimidazole and 2-ethyl-4-methylimidazole. The imidazole catalyst serves as a catalyst for the reaction between the dicarboxylic acid and the epoxy group.

[0030] The present application provides a method for preparing the above-mentioned tire innerliner composite material, which is characterized in that the preparation method includes the following steps: 1) In a mixer, with a filling coefficient of 0.6 - 0.8, add epoxidized natural rubber, epoxidized iron-based comb-branched butadiene-pentene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer, and reinforcing filler for mixing. The mixing temperature is 135 - 155 °C, and the mixing time is 180 - 360 s. After mixing is completed, a first-stage mixed rubber is obtained; 2) Add the first-stage mixed rubber, sulfur, accelerator, and imidazole catalyst to the mixer. The mixing temperature is 70 - 80 °C, and the mixing time is 120 - 180 s to obtain a second-stage mixed rubber; 3) Put the second-stage mixed rubber into a mold for vulcanization. The vulcanization temperature is 130 - 160 °C to obtain the tire innerliner composite material.

[0031] The present application provides the application of the above-mentioned tire innerliner composite material in tires, which is used for the innerliners of passenger car tires, motorcycle tires, and truck tires.

[0032] The beneficial effects of the present application include but are not limited to: 1. The tire airtight layer composite material according to the present application, its preparation method and application. By blending and compounding epoxidized natural rubber with iron-based comb-branched butyl-pentyl rubber, the mechanical properties are improved without sacrificing the airtightness of the material. Secondly, by adding metal salts and dicarboxylic acids that can react with epoxy groups, metal-epoxy group coordination bonds and β-hydroxy ester bonds are formed inside the material. These coordination bonds and dynamic covalent bonds endow the material with fast self-healing performance, and the performance of the repaired material shows no obvious attenuation compared with the raw material.

[0033] 2. The tire airtight layer composite material according to the present application, its preparation method and application. The butyl-pentyl rubber itself has a relatively fast vulcanization rate, and the introduction of epoxy groups can further improve the vulcanization rate of the rubber composite material.

[0034] 3. The tire airtight layer composite material according to the present application, its preparation method and application. In the iron-based comb-branched butyl-pentyl rubber used in the present application, hydrogen bond interactions are easily formed between epoxy groups, further compressing the free volume between molecular chains. Coupled with the relatively high side group content of the iron-based comb-branched butyl-pentyl rubber itself, the tire airtight layer composite material has excellent airtightness.

[0035] 4. The tire airtight layer composite material according to the present application, its preparation method and application. On the one hand, a part of the 1,4-isoprene structure is contained in the molecular chain of the iron-based comb-branched butyl-pentyl rubber, which has a relatively high structural similarity with the isoprene chain segment in natural rubber. On the other hand, the epoxy groups existing in both epoxidized natural rubber and iron-based comb-branched butyl-pentyl rubber can form extensive hydrogen bond interactions between molecular chains, so that different rubbers have higher compatibility during the mixing process. After vulcanization and crosslinking, the molecular chain segments are entangled and combined with each other to form a homogeneous structure of "you have me, and I have you", which can maximize the advantages of natural rubber and iron-based comb-branched butyl-pentyl rubber, and the synergistic effect is more obvious, making the tire airtight layer composite material of the present application scheme have better comprehensive performance. Description of the Drawings

[0036] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings: Figure 1 It is a schematic diagram of the puncture object specifications involved in the test example of the present application. Detailed Embodiments

[0037] The present application will be described in detail below with reference to embodiments, but the present application is not limited to these embodiments. Unless otherwise specified, the raw materials and reagents in the embodiments of the present application are purchased through commercial channels.

[0038] The preparation of the epoxidized iron-based comb-shaped butadiene-isoprene rubber in the solution of the present application can refer to the disclosure in Patent CN117603378A. The solution of the present application will be described below through specific examples.

[0039] Example 1 The self-healing tire airtight layer composite material of this example includes, by weight: 30 parts of epoxidized natural rubber; 80 parts of epoxidized iron-based comb-shaped butadiene-isoprene rubber; 1 part of ferric chloride and 1 part of aluminum chloride; 2 parts of binary carboxylic acid suberic acid; 50 parts of reinforcing filler carbon black N110; 20 parts of plasticizer DBP; 3 parts of zinc oxide; 2 parts of stearic acid; 1.5 parts of sulfur; 1 part of sulfenamide accelerator CZ; 0.5 part of imidazole catalyst 2-ethyl-4-methylimidazole.

[0040] Among them, the epoxidation degree of the epoxidized natural rubber is 20%.

[0041] Among them, the number average molecular weight of the epoxidized iron-based comb-shaped butadiene-isoprene rubber is 540,000, the epoxidation degree is 20%, and the side group content is 71%; the epoxidized iron-based comb-shaped butadiene-isoprene rubber is a gel-free epoxidized iron-based comb-shaped butadiene-isoprene rubber.

[0042] The raw material of the epoxidized iron-based comb-shaped butadiene-isoprene rubber, that is, the iron-based comb-shaped butadiene-isoprene rubber, is composed of random copolymerization of isoprene and butadiene; among them, the isoprene structure is composed of 3,4-isoprene and 1,4-isoprene; the butadiene structure is composed of 1,2-butadiene and 1,4-butadiene; the iron-based comb-shaped butadiene-isoprene rubber is prepared by coordination polymerization using an iron-based catalyst. During the preparation process, the molar ratio of monomer butadiene to isoprene is 1:1. The molar content of the butadiene structure in the epoxidized iron-based comb-shaped butadiene-isoprene rubber is 50%, and the molar content of the isoprene structure in the epoxidized iron-based comb-shaped butadiene-isoprene rubber is 50%.

[0043] The molar content of 1,2-butadiene in the butadiene structure of the iron-based comb-shaped butadiene-isoprene rubber is 69%, and the total molar content of cis-1,4-butadiene and trans-1,4-butadiene accounts for 31% of the total butadiene structure; the molar content of 3,4-isoprene in the isoprene structure of the epoxidized iron-based comb-shaped butadiene-isoprene rubber is 73%, and the total molar content of cis-1,4-isoprene and trans-1,4-isoprene accounts for 27% of the total isoprene structure.

[0044] The preparation steps are as follows: 1) In the internal mixer, with a filling coefficient of 0.7, epoxidized natural rubber, epoxy iron-based comb-shaped butadiene-pentadiene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer and reinforcing filler are added for mixing. The mixing temperature is 145 °C and the mixing time is 270 s. After mixing, a first-stage mixed rubber is obtained; 2) The first-stage mixed rubber, sulfur, accelerator and imidazole catalyst are added to the internal mixer. The mixing temperature is 75 °C and the mixing time is 150 s to obtain a second-stage mixed rubber; 3) The second-stage mixed rubber is put into a mold for vulcanization at a vulcanization temperature of 145 °C to obtain the tire airtight layer composite material.

[0045] Example 2 The self-healing tire airtight layer composite material of this example includes by weight: 20 parts of epoxidized natural rubber; 50 parts of epoxy iron-based comb-shaped butadiene-pentadiene rubber; 0.5 part of aluminum trichloride; 1 part of dicarboxylic acid octanedioic acid; 20 parts of reinforcing filler carbon black N110; 10 parts of plasticizer DOP; 1 part of zinc oxide; 0.5 part of stearic acid; 0.1 part of sulfur; 0.1 part of sulfenamide accelerator CZ; 0.1 part of imidazole catalyst 2-ethyl-4-methylimidazole.

[0046] Among them, the epoxidation degree of epoxidized natural rubber is 20%.

[0047] Among them, the number-average molecular weight of the epoxy iron-based comb-shaped butadiene-pentadiene rubber is 420,000, the epoxidation degree is 31%, and the side group content is 69%; the epoxy iron-based comb-shaped butadiene-pentadiene rubber is a gel-free epoxy iron-based comb-shaped butadiene-pentadiene rubber.

[0048] The raw material of the epoxy iron-based comb-shaped butadiene-pentadiene rubber, that is, the iron-based comb-shaped butadiene-pentadiene rubber, is composed of random copolymerization of isoprene and butadiene; among them, the isoprene structure is composed of 3,4-isoprene and 1,4-isoprene; the butadiene structure is composed of 1,2-butadiene and 1,4-butadiene; the iron-based comb-shaped butadiene-pentadiene rubber is prepared by coordination polymerization using an iron-based catalyst. During the preparation process, the molar ratio of monomer butadiene to isoprene is 1:1. The molar content of the butadiene structure in the obtained epoxy iron-based comb-shaped butadiene-pentadiene rubber is 50%, and the molar content of the isoprene structure in the epoxy iron-based comb-shaped butadiene-pentadiene rubber is 50%.

[0049] In the iron-based comb-branched butyl-pentene rubber, the molar content of 1,2-butadiene in the butadiene structure is 68%, and the total molar content of cis-1,4-butadiene and trans-1,4-butadiene accounts for 32% of the total butadiene structure; in the epoxidized iron-based comb-branched butyl-pentene rubber, the molar content of 3,4-isoprene in the isoprene structure is 70%, and the total molar content of cis-1,4-isoprene and trans-1,4-isoprene accounts for 30% of the total isoprene structure.

[0050] The preparation steps are as follows: 1) In a Banbury mixer with a filling coefficient of 0.6, epoxidized natural rubber, epoxidized iron-based comb-branched butyl-pentene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer, and reinforcing filler are added for mixing. The mixing temperature is 135 °C, and the mixing time is 360 s. After mixing, the first-stage mixed rubber is obtained. 2) The first-stage mixed rubber, sulfur, accelerator, and imidazole catalyst are added to the Banbury mixer. The mixing temperature is 80 °C, and the mixing time is 120 s to obtain the second-stage mixed rubber. 3) The second-stage mixed rubber is put into a mold for vulcanization at a vulcanization temperature of 150 °C to obtain the tire airtight layer composite material.

[0051] Example 3 The self-healing tire airtight layer composite material of this example includes the following components by weight: 50 parts of epoxidized natural rubber; 100 parts of epoxidized iron-based comb-branched butyl-pentene rubber; 2 parts of ferric chloride; 3 parts of dicarboxylic acid octanedioic acid; 80 parts of reinforcing filler carbon black N110; 30 parts of paraffin oil plasticizer; 5 parts of zinc oxide; 3 parts of stearic acid; 3 parts of sulfur; 2 parts of sulfenamide accelerator NS; 1 part of imidazole catalyst 1-methylimidazole.

[0052] Among them, the epoxidation degree of the epoxidized natural rubber is 40%.

[0053] Among them, the number-average molecular weight of the epoxidized iron-based comb-branched butyl-pentene rubber is 700,000, the epoxidation degree is 10%, and the side group content is 67%; the epoxidized iron-based comb-branched butyl-pentene rubber is an epoxidized iron-based comb-branched butyl-pentene rubber without gel.

[0054] The raw material of the epoxidized iron-based comb-branched butyl-pentene rubber, namely the iron-based comb-branched butyl-pentene rubber, is composed of random copolymerization of isoprene and butadiene; among them, the isoprene structure is composed of 3,4-isoprene and 1,4-isoprene; the butadiene structure is composed of 1,2-butadiene and 1,4-butadiene; the epoxidized iron-based comb-branched butyl-pentene rubber is prepared by coordination polymerization using an iron-based catalyst. During the preparation process, the molar ratio of monomer butadiene to isoprene is 1:1. The molar content of the butadiene structure in the obtained epoxidized iron-based comb-branched butyl-pentene rubber is 50%, and the molar content of the isoprene structure in the epoxidized iron-based comb-branched butyl-pentene rubber is 50%.

[0055] In the iron-based comb-branched butyl-pentene rubber, the molar content of 1,2-butadiene in the butadiene structure is 67%, and the total molar content of cis-1,4-butadiene and trans-1,4-butadiene accounts for 33% of the total butadiene structure; in the epoxidized iron-based comb-branched butyl-pentene rubber, the molar content of 3,4-isoprene in the isoprene structure is 67%, and the total molar content of cis-1,4-isoprene and trans-1,4-isoprene accounts for 33% of the total isoprene structure.

[0056] The preparation steps are as follows: 1) In an internal mixer with a filling coefficient of 0.8, add epoxidized natural rubber, epoxidized iron-based comb-branched butyl-pentene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer and reinforcing filler for mixing. The mixing temperature is 155 °C and the mixing time is 180 s. After mixing, a first-stage mixed rubber is obtained; 2) Add the first-stage mixed rubber, sulfur, accelerator and imidazole catalyst to the internal mixer. The mixing temperature is 70 °C and the mixing time is 180 s to obtain a second-stage mixed rubber; 3) Put the second-stage mixed rubber into a mold for vulcanization at a vulcanization temperature of 130 °C to obtain the tire airtight layer composite material.

[0057] Example 4 This example is basically the same as Example 1, except that the dicarboxylic acid is sebacic acid.

[0058] Example 5 This example is basically the same as Example 1, except that the dicarboxylic acid is succinic acid.

[0059] Example 6 This example is basically the same as Example 1, except that the dicarboxylic acid is terephthalic acid.

[0060] Example 7 This example is basically the same as Example 1, except that the metal salt (iron(III) chloride and aluminum(III) chloride) is an equal total amount of copper(II) chloride.

[0061] Comparative Example 1 This comparative example is basically the same as Example 1, except that the epoxidized natural rubber is replaced with an equal amount of epoxidized iron-based comb-shaped butadiene-pentene rubber.

[0062] Comparative Example 2 This comparative example is basically the same as Example 1, except that the epoxidized iron-based comb-shaped butadiene-pentene rubber is replaced with an equal amount of epoxidized natural rubber.

[0063] Comparative Example 3 This comparative example is basically the same as Example 1, except that the dicarboxylic acid is replaced with an equal amount of metal salts (the dosage ratio of ferric chloride and aluminum chloride is 1:1).

[0064] Comparative Example 4 This comparative example is basically the same as Example 1, except that the metal salts (ferric chloride and aluminum chloride) are replaced with an equal amount of dicarboxylic acid.

[0065] Test Example 1 The performance of the obtained tire inner liner composite material was detected, and the results are shown in Table 1 below.

[0066] The performance detection contents involved include: T90 represents the time required for the torque of the rubber to reach 90% of the maximum torque (MH) during vulcanization. It is tested with a rotor vulcanizer at a test temperature of 160 °C; The detection methods for tensile strength, elongation at break, and 300% modulus are referred to GB / T 528-2009 "Rubber, vulcanized or thermoplastic - Determination of tensile stress - strain properties"; The detection method for tear strength is referred to GB / T 529-2008 "Rubber, vulcanized or thermoplastic - Determination of tear strength (trouser, right angle and crescent specimens)"; The detection method for fatigue life is referred to GB / T 1688-2008 "Rubber, vulcanized - Determination of flex fatigue", with the strain set to 100%; The detection method for gas permeability coefficient is referred to GB / T 1038-2000 "Plastics - Film and sheeting - Determination of gas permeability - Manometric method"; The self-healing performance test is carried out by piercing the specimen with a puncture object as shown in Figure 1 In order to accelerate the self-healing speed, the punctured sample is placed in an oven at 60 °C, and then the tensile strength and gas permeability coefficient at the puncture site are tested after taking it out.

[0067] Table 1

[0068] Continued Table 1

[0069] According to the results in Table 1, Examples 1-7 demonstrate the mechanical properties, airtightness, and self-healing properties of the tire inner liner composites under different rubber ratios, different crosslinker dosages, and different filler filling amounts.

[0070] Examples 1, 4, and 5 show that long-chain dicarboxylic acids as crosslinkers are beneficial to improving the tensile properties, tear resistance, fatigue resistance, airtightness, and self-healing rate of the material. The dicarboxylic acid used in Example 6 contains a benzene ring structure, which is beneficial to improving the tensile properties of the material, and the tensile strength increases significantly, but the fatigue resistance of the material decreases significantly. Examples 1 and 7 show that trivalent metal salts have a more significant improvement in tensile properties and self-healing rate than divalent metal salts.

[0071] Comparative Example 1 shows that only using epoxidized iron oxide-based comb-branched butyl rubber as the matrix can significantly improve the airtightness of the material, but the mechanical properties of the material decrease significantly. Comparative Example 2 shows that only using epoxidized natural rubber as the matrix, the material has excellent mechanical properties, but the airtightness of the material is poor. Comparative Examples 3 and 4 show that only using a single crosslinker, the self-healing time of the material is long and the healing effect is poor, while the combination of metal salts and dicarboxylic acids used in the examples plays a better synergistic effect.

[0072] As described above, the above are only the embodiments of the present application. The protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the technical idea and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A self-healing composite material for the airtight layer of a tire, characterized in that, By weight parts, the tire inner liner composite material comprises: 10 - 50 parts of epoxidized natural rubber; 50 - 100 parts of epoxy iron - based comb - branched butadiene - isoprene rubber; 0.5 - 2 parts of metal salt; 1 - 3 parts of dicarboxylic acid; 20 - 80 parts of reinforcing filler; 10 - 30 parts of plasticizer; 1 - 5 parts of zinc oxide; 0.5 - 3 parts of stearic acid; 0.1 - 3 parts of sulfur; 0.1 - 2 parts of accelerator; 0.1 - 1 part of imidazole - type catalyst; The number - average molecular weight of the epoxy iron - based comb - branched butadiene - isoprene rubber is 300,000 - 900,000, and the epoxy degree is 10% - 30%; the metal salt is one or more of iron salts, aluminum salts and copper salts.

2. The self-healing tire airtight layer composite material according to claim 1, wherein The epoxy iron - based comb - branched butadiene - isoprene rubber is obtained by epoxidation modification of iron - based comb - branched butadiene - isoprene rubber with one or more of hydrogen peroxide, performic acid or peracetic acid.

3. The self-healing tire airtight layer composite material according to claim 2, wherein The epoxy iron - based comb - branched butadiene - isoprene rubber is a gel - free epoxy iron - based comb - branched butadiene - isoprene rubber.

4. The self-healing tire airtight layer composite material according to claim 2, characterized in that, The iron - based comb - branched butadiene - isoprene rubber is composed of random copolymerization of isoprene and butadiene, and the side - group content is 60% - 80%; Among them, the isoprene includes 3,4 - isoprene and 1,4 - isoprene, and the butadiene includes 1,2 - butadiene and 1,4 - butadiene.

5. The self-healing tire airtight layer composite material according to claim 4, characterized in that, The molar content of 1,2 - butadiene in the butadiene is 60% - 80%; and / or, The molar content of 3,4 - isoprene in the isoprene is 60% - 80%.

6. The self-healing tire airtight layer composite material according to claim 4, characterized in that, The metal salt is one or more of ferric chloride, aluminum chloride, cupric chloride.

7. The self-healing tire airtight layer composite material according to claim 1, characterized in that, The dicarboxylic acid is one or more of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, methylmalonic acid, 2 - methylsuccinic acid, 2 - methylglutaric acid, 2,2,3,3 - tetramethylsuccinic acid, 1,4 - cyclohexanedicarboxylic acid, 2,2 - dimethyl - 3 - carboxycyclobutaneacetic acid, 1,2,2 - trimethylcyclopentane - 1,3 - dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, o - biphenyl - dicarboxylic acid, o - diphenylether - dicarboxylic acid and p - diphenylether - dicarboxylic acid.

8. The self-healing tire airtight layer composite material according to claim 1, characterized in that The reinforcing filler is one or more of carbon black N110, N219, N220, N231, N234, N326, N330; and / or, The plasticizer is one or more of aromatic oil, naphthenic oil, paraffin oil, DOP, DBP; and / or, The accelerator is a sulfenamide - type accelerator; and / or, The imidazole - type catalyst is one or two of 1 - methylimidazole, 2 - ethyl - 4 - methylimidazole.

9. The preparation method of the tire airtight layer composite material according to any one of claims 1 to 8, characterized in that, The preparation method comprises the following steps: 1) In an internal mixer, with a filling coefficient of 0.6 - 0.8, add epoxidized natural rubber, epoxy iron - based comb - branched butadiene - isoprene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer and reinforcing filler for mixing. The mixing temperature is 135 - 155 °C, and the mixing time is 180 - 360 s. After mixing, obtain a first - stage mixed rubber; 2) Add the first - stage mixed rubber, sulfur, accelerator and imidazole - type catalyst into the internal mixer. The mixing temperature is 70 - 80 °C, and the mixing time is 120 - 180 s to obtain a second - stage mixed rubber. 3) Put the two-stage mixed rubber into a mold for vulcanization at a vulcanization temperature of 130~160°C to obtain the tire airtight layer composite material.

10. The application of the tire airtight layer composite material according to any one of claims 1~8 in a tire, which is used for the airtight layer of a passenger car tire, a motorcycle tire, and a truck tire.

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