A self-repairing tire inner liner composite material and its preparation method and application

Abstract

This application discloses a self-repairing tire innerliner composite material, its preparation method, and application, belonging to the technical field of tire innerliner materials. The material comprises: 10-50 parts of epoxidized natural rubber; 50-100 parts of epoxidized iron-based combed butadiene-vinyl rubber; 0.5-2 parts of a metal salt; 1-3 parts of a dicarboxylic acid; 20-80 parts of a reinforcing filler; 10-30 parts of a 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 an accelerator; and 0.1-1 parts of an imidazole catalyst. The epoxidized iron-based combed butadiene-vinyl rubber has a number-average molecular weight of 30-90w and a degree of epoxidation of 10-30%. The metal salt is one or more of an iron salt, an aluminum salt, and a copper salt. This application prepares a composite material for tire airtight layers with excellent self-repairing and airtight properties by blending epoxidized natural rubber with epoxidized iron-based combed butadiene-pentadiene rubber, and then using metal salts, dicarboxylic acids and sulfur as cross-linking agents. Compared with the tire airtight layer materials in the existing technology, the composite material has obvious performance advantages and can improve the overall performance of the tire.

Description

Technical Field

[0001] The present application relates to a self-repairing tire inner liner composite material, a preparation method thereof, and an application thereof, and belongs to the technical field of tire inner liner materials. Background Art

[0002] With the continuous development of the automotive industry, people are paying more and more attention to the performance of their vehicles. As the only contact medium between a vehicle and the ground, tire performance directly affects the vehicle's driving comfort and safety during dynamic movement. Furthermore, as a consumable auto part, tire performance also affects the vehicle's service life and fuel economy.

[0003] Since the invention of the tire, it has undergone numerous changes, with vacuum radial tires gradually replacing older tube-type tires. Vacuum tires are known for their superior safety (a certain degree of self-sealing ability), improved wear resistance (direct contact between the tire and the wheel hub, better heat dissipation, and improved wear resistance), better fuel economy (maintaining good driving stability and low friction, which helps reduce shock and increase vehicle speed), and a more comfortable driving experience (the tire and wheel rim are sealed together, with high manufacturing precision, good tire-to-tire alignment, and reduced radial runout).

[0004] To function as a gas container, vacuum tires must maintain excellent airtightness to ensure stable operation. Butyl rubber, with its abundant side groups and unique spatial helical structure, can prevent gas from passing between molecular chains. Its airtightness is approximately 10 times that of natural rubber, making it an ideal base material for innerliners.

[0005] Although butyl rubber has excellent air tightness, when used in rubber composites, its low content of unsaturated chemical bonds leads to a slow vulcanization rate, poor processing performance, and its adhesion and mutual adhesion need to be improved. In addition, when used as an airtight layer material, butyl rubber also has the problems of poor flexibility and large hysteresis deformation, which leads to high dynamic heat generation.

[0006] Patent CN116285135A provides a rubber composite material with both high air tightness and tear resistance, as well as its preparation method and application. Iron-based combed butadiene-pentadiene rubber, which also has a high side group content, is introduced into butyl rubber to improve its vulcanization processing performance and flexibility. However, since this material also has a high side group content, the problem of high dynamic heat generation still exists; at the same time, since this material does not have self-repairing properties during actual use, once the tire airtight layer is punctured by a sharp object, its airtightness will be permanently reduced, 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 a preparation method thereof. However, its tensile strength, tensile stress at constant elongation and air tightness still need to be improved, and it also does not have self-repairing properties.

[0008] Therefore, developing a tire airtight layer material with both excellent airtightness and self-repairing properties is of great significance to the manufacturing of high-performance tires. Summary of the Invention

[0009] In order to solve the above problems, a self-repairing tire airtight layer composite material and its preparation method and application are provided. By blending and compounding epoxidized natural rubber with epoxidized iron-based combed butadiene-pentadiene rubber, 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-hydroxy ester bonds are formed inside the material. These metal coordination bonds and dynamic covalent bonds give the material rapid self-repairing properties and the repaired material has no performance degradation compared to the raw material. The tire airtight layer composite material provided by the present application scheme has obvious performance advantages over the products in the prior art, can improve the comprehensive performance of the tire, and has important market application potential.

[0010] The present application provides a self-repairing tire inner liner composite material, which comprises, by weight:

[0011] 10-50 parts of epoxidized natural rubber;

[0012] Epoxy iron-based combed butadiene-pentadiene rubber 50-100 parts;

[0013] 0.5-2 parts of metal salt;

[0014] 1-3 parts of dicarboxylic acid;

[0015] 20~80 parts of reinforcing filler;

[0016] 10-30 parts of plasticizer;

[0017] 1-5 parts of zinc oxide;

[0018] 0.5-3 parts of stearic acid;

[0019] 0.1~3 parts of sulfur;

[0020] 0.1~2 parts of accelerator;

[0021] 0.1~1 part of imidazole catalyst;

[0022] The molecular weight of the epoxidized iron-based combed butadiene-pentadiene rubber is 30-90w, and the epoxidation degree is 10-30%; the metal salt is one or more of iron salt, aluminum salt and copper salt.

[0023] The present application provides a self-repairing tire airtight layer composite material, in which the metal ions in the metal salt can form coordination bonds with the epoxy groups in the rubber, which are non-covalent bonds. After being destroyed by external force, they can absorb part of the energy and re-bond quickly, thereby accelerating the self-repair speed. In combination with dicarboxylic acid, they form β-hydroxy ester bonds with the epoxy groups in the rubber, which are dynamic covalent bonds. The self-repair speed is slow but the bond energy is large, so that the repaired material has a higher strength again, thereby making the airtight layer composite material have both excellent self-repairing performance and airtight performance.

[0024] In this application, epoxidized iron-based combed butadiene-pentadiene rubber (P-butyl) is combined with epoxidized natural rubber. The epoxidized iron-based combed butadiene-pentadiene rubber (P-butyl) has a chemical structure similar to butyl rubber, such as a high content of side groups and excellent air tightness. Furthermore, after epoxidation, the molecular chains interact more closely, further improving air tightness and bonding with the belt layer. The epoxy groups in the epoxidized iron-based combed butadiene-pentadiene rubber and epoxidized natural rubber provide active sites, laying the foundation for the material's self-healing function. The synergistic combination with metal salts and dicarboxylic acids gives it significant performance advantages over existing tire innerliner materials, enhancing the overall performance of the tire.

[0025] Optionally, the epoxidized iron-based combed butadiene rubber is obtained by epoxidizing the iron-based combed butadiene rubber with one or more of hydrogen peroxide, performic acid or peracetic acid. The degree of epoxidation refers to the proportion of the original carbon-carbon double bonds on the rubber molecular chain that are converted into epoxy groups.

[0026] Optionally, the epoxidized iron-based combed butadiene rubber is a gel-free epoxidized iron-based combed butadiene rubber. If gel is formed during the epoxidation process, the iron-based combed butadiene rubber undergoes premature crosslinking, which has an adverse effect on subsequent performance.

[0027] Optionally, the iron-based combed butadiene-pentadiene rubber is composed of random copolymerization of isoprene and butadiene, with a side group content of 60-80%.

[0028] Optionally, the iron-based combed butadiene-vinyl rubber is composed of random copolymerization of isoprene and butadiene, and the molar ratio of butadiene to isoprene is 1:(1-10).

[0029] Optionally, the iron-based combed butadiene-vinyl 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 better improve the air tightness.

[0030] Among them, isoprene includes 3,4-isoprene and 1,4-isoprene, and butadiene includes 1,2-butadiene and 1,4-butadiene.

[0031] Optionally, the molar content of 1,2-butadiene in the butadiene is 60-80%;

[0032] Optionally, the molar content of 3,4-isoprene in the isoprene is 60-80%.

[0033] In this application, iron-based combed butadiene rubber with specific properties is selected as the raw material for preparing epoxidized iron-based combed butadiene rubber mainly due to the following reasons: (1) The butadiene rubber with this structure has a higher side group content and a smaller free volume between molecular chains, which hinders the diffusion of gas molecules inside the material, thereby achieving better airtightness when used as an airtight layer material; (2) The butadiene rubber with this structure has more side double bonds than butyl rubber, so it has a faster vulcanization speed and is easy to process and shape; (3) The main chain of the butadiene rubber with this structure is less damaged during the epoxidation process, which can retain the high molecular weight of the rubber and its own excellent properties to the greatest extent.

[0034] Optionally, the epoxidized natural rubber has a degree of epoxidation of 20-40%. Epoxidized natural rubber primarily serves as a reinforcement in the system of this application. The epoxidized natural rubber improves its compatibility with the epoxidized iron-based combed butadiene-pentadiene rubber (B-P-ER). However, excessive epoxidation can compromise the rubber's elasticity. Controlling the degree of epoxidation within the above range ensures the strength of the epoxidized iron-based combed butadiene-pentadiene rubber while also improving system compatibility and ensuring its elastic properties.

[0035] 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-diphenyl dicarboxylic acid, o-diphenyl ether dicarboxylic acid and p-diphenyl ether dicarboxylic acid.

[0036] Optionally, the dicarboxylic acid is one or more of pimelic acid, suberic acid, azelaic acid, and sebacic acid. The long-chain carboxylic acid molecules mentioned above are more flexible in structure, thus being more conducive to improving the toughness of the airtight layer composite material.

[0037] Optionally, the dicarboxylic acid is suberic acid or sebacic acid. The airtight layer material prepared by selecting the above-mentioned long-chain carboxylic acid molecules has better comprehensive properties.

[0038] Optionally, the metal salt is one or more of ferric chloride, aluminum chloride, and copper dichloride.

[0039] Optionally, the metal salt includes one or both of ferric chloride and aluminum chloride. The trivalent metal salts mentioned above are selected because the metal ions have a higher charge density, resulting in stronger electrostatic attraction between the metal ions and the partially negatively charged oxygen atoms in the epoxy groups, more stable coordination bonds, greater bond energy, and better self-healing properties.

[0040] Optionally, the reinforcing filler is one or more of carbon black N110, N219, N220, N231, N234, N326, and N330;

[0041] Optionally, the plasticizer is one or more of aromatic oil, naphthenic oil, paraffin oil, DOP, and DBP;

[0042] Optionally, the accelerator is a sulfenamide accelerator. In the system of the present application, it has good anti-scorch performance.

[0043] Optionally, the sulfenamide accelerator is one or both of accelerator CZ and accelerator NS.

[0044] Optionally, the imidazole catalyst is one or both of 1-methylimidazole and 2-ethyl-4-methylimidazole, and the imidazole catalyst serves as a catalyst for the reaction between the dicarboxylic acid and the epoxy group.

[0045] The present application provides a method for preparing the above-mentioned tire inner liner composite material, characterized in that the preparation method comprises the following steps:

[0046] 1) In an internal mixer, epoxidized natural rubber, epoxidized iron-based combed butadiene-pentadiene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer, and reinforcing filler are added and mixed at a filling factor of 0.6-0.8. The mixing temperature is 135-155°C and the mixing time is 180-360 seconds. After mixing, a rubber compound is obtained.

[0047] 2) Add the first-stage rubber mix, sulfur, accelerator, and imidazole catalyst into an internal mixer at a mixing temperature of 70-80°C for 120-180 seconds to obtain a second-stage rubber mix;

[0048] 3) placing the second-stage rubber mix into a mold for vulcanization at a vulcanization temperature of 130-160° C. to obtain the tire innerliner composite material.

[0049] The present application provides the application of the above tire airtight layer composite material in tires, which is used for the airtight layers of passenger car tires, motorcycle tires and truck tires.

[0050] The beneficial effects of this application include but are not limited to:

[0051] 1. The tire innerliner composite material, preparation method, and application disclosed herein utilizes a blend of epoxidized natural rubber and epoxidized iron-based combed butadiene-pentadiene rubber to enhance mechanical properties without sacrificing airtightness. Furthermore, the addition of metal salts and dicarboxylic acids reactive with epoxy groups allows for the formation of metal-epoxy coordination bonds and β-hydroxyester bonds within the material. These coordination bonds and dynamic covalent bonds impart rapid self-healing properties to the material, with no significant degradation in performance compared to the original material.

[0052] 2. According to the tire airtight layer composite material and its preparation method and application of the present application, the butadiene-vinyl rubber itself has a relatively fast vulcanization speed, and the introduction of epoxy groups can further increase the vulcanization speed of the rubber composite material.

[0053] 3. According to the tire innerliner composite material, its preparation method, and its use described herein, the epoxy groups in the epoxidized iron-based combed butadiene-vinyl rubber used herein readily form hydrogen bonds, further compressing the free volume between the molecular chains. Combined with the high pendant group content of the iron-based combed butadiene-vinyl rubber itself, the tire innerliner composite material exhibits excellent airtightness.

[0054] 4. According to the tire innerliner composite material of the present application, its preparation method, and application, on the one hand, the molecular chain of the epoxidized iron-based combed butadiene-vinyl rubber contains a portion of 1,4-isoprene structure, which has a high structural similarity to the isoprene chain segment in natural rubber. On the other hand, the epoxidized groups present in both the epoxidized natural rubber and the epoxidized iron-based combed butadiene-vinyl rubber can form extensive hydrogen bonding between the molecular chains, thereby enhancing compatibility between the different rubbers during the mixing process. After vulcanization and cross-linking, the molecular segments entangle and bond with each other, forming a homogeneous "you-in-me-me" structure. This maximizes the advantageous properties of natural rubber and the iron-based combed butadiene-vinyl rubber, enhances synergistic effects, and thus gives the tire innerliner composite material of the present application scheme excellent overall performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0056] Figure 1 This is a schematic diagram of the specifications of the puncture object involved in the test example of this application. DETAILED DESCRIPTION

[0057] The present application is described in detail below with reference to examples, but the present application is not limited to these examples. Unless otherwise specified, the raw materials and reagents in the examples of the present application are purchased through commercial channels.

[0058] The preparation of the epoxidized iron-based combed butadiene-vinyl rubber in the present application can refer to the disclosure in patent CN117603378A. The present application will be described below through specific examples.

[0059] Example 1

[0060] The self-repairing tire inner liner composite material of this embodiment comprises, by weight:

[0061] 30 parts of epoxidized natural rubber;

[0062] 80 parts of epoxidized iron-based combed butadiene-pentadiene rubber;

[0063] 1 part of ferric chloride, 1 part of aluminum chloride;

[0064] 2 parts of dicarboxylic acid suberic acid;

[0065] 50 parts of reinforcing filler carbon black N110;

[0066] Plasticizer DBP 20 parts;

[0067] 3 parts zinc oxide;

[0068] 2 parts of stearic acid;

[0069] 1.5 parts of sulfur;

[0070] 1 part of sulfenamide accelerator CZ;

[0071] 0.5 parts of imidazole catalyst 2-ethyl-4-methylimidazole.

[0072] The epoxidation degree of the epoxidized natural rubber is 20%.

[0073] The number average molecular weight of the epoxidized iron-based combed butadiene rubber is 54w, the epoxidation degree is 20%, and the side group content is 71%; the epoxidized iron-based combed butadiene rubber is an epoxidized iron-based combed butadiene rubber that does not contain gel.

[0074] The raw materials of the epoxidized iron-based combed butadiene rubber, i.e., the iron-based combed butadiene rubber, are composed of random copolymers of isoprene and butadiene; wherein the isoprene structure is composed of 3,4-isoprene and 1,4-isoprene; and the butadiene structure is composed of 1,2-butadiene and 1,4-butadiene; the iron-based combed butadiene rubber is prepared by coordination polymerization using an iron-based catalyst, wherein the molar ratio of the monomers butadiene to isoprene is 1:1 during the preparation process, the molar content of the butadiene structure in the epoxidized iron-based combed butadiene rubber is 50%, and the molar content of the isoprene structure in the epoxidized iron-based combed butadiene rubber is 50%.

[0075] The molar content of 1,2-butadiene in the butadiene structure of iron-based combed butadiene 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 epoxidized iron-based combed butadiene 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.

[0076] The preparation steps are as follows:

[0077] 1) In an internal mixer, epoxidized natural rubber, epoxidized iron-based combed butadiene-pentadiene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer, and reinforcing filler were added and mixed at a filling factor of 0.7. The mixing temperature was 145°C and the mixing time was 270 seconds. After the mixing was completed, a rubber compound was obtained.

[0078] 2) Add the first-stage rubber mix, sulfur, accelerator, and imidazole catalyst into an internal mixer at a mixing temperature of 75°C for 150 seconds to obtain a second-stage rubber mix;

[0079] 3) placing the second-stage rubber mix into a mold for vulcanization at a vulcanization temperature of 145° C. to obtain the tire innerliner composite material.

[0080] Example 2

[0081] The self-repairing tire inner liner composite material of this embodiment comprises, by weight:

[0082] 20 parts of epoxidized natural rubber;

[0083] 50 parts of epoxidized iron-based combed butadiene-pentadiene rubber;

[0084] 0.5 parts of aluminum chloride;

[0085] 1 part of dicarboxylic acid suberic acid;

[0086] 20 parts of reinforcing filler carbon black N110;

[0087] Plasticizer DOP 10 parts;

[0088] 1 part zinc oxide;

[0089] 0.5 parts of stearic acid;

[0090] 0.1 part of sulfur;

[0091] 0.1 part of sulfenamide accelerator CZ;

[0092] 0.1 parts of imidazole catalyst 2-ethyl-4-methylimidazole.

[0093] The epoxidation degree of the epoxidized natural rubber is 20%.

[0094] Among them, the number average molecular weight of the epoxidized iron-based combed butadiene rubber is 42w, the epoxidation degree is 31%, and the side group content is 69%; the epoxidized iron-based combed butadiene rubber is an epoxidized iron-based combed butadiene rubber that does not contain gel.

[0095] The raw materials of epoxidized iron-based combed butadiene rubber, i.e., iron-based combed butadiene rubber, are composed of random copolymers of isoprene and butadiene; the isoprene structure is composed of 3,4-isoprene and 1,4-isoprene; and the butadiene structure is composed of 1,2-butadiene and 1,4-butadiene. The iron-based combed butadiene rubber is prepared by coordination polymerization using an iron-based catalyst. During the preparation process, the molar ratio of the monomers butadiene to isoprene is 1:1. The molar content of the butadiene structure in the obtained epoxidized iron-based combed butadiene rubber is 50%, and the molar content of the isoprene structure in the epoxidized iron-based combed butadiene rubber is 50%.

[0096] The molar content of 1,2-butadiene in the butadiene structure of iron-based combed butadiene rubber 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; the molar content of 3,4-isoprene in the isoprene structure of epoxidized iron-based combed butadiene rubber 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.

[0097] The preparation steps are as follows:

[0098] 1) In an internal mixer, epoxidized natural rubber, epoxidized iron-based combed butadiene-pentadiene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer, and reinforcing filler were added and mixed at a filling factor of 0.6 at a mixing temperature of 135°C for 360 seconds to obtain a first-stage rubber mix.

[0099] 2) Add the first-stage rubber mix, sulfur, accelerator, and imidazole catalyst into an internal mixer at a mixing temperature of 80°C for 120 seconds to obtain a second-stage rubber mix;

[0100] 3) placing the second-stage rubber mix into a mold for vulcanization at a vulcanization temperature of 150° C. to obtain the tire innerliner composite material.

[0101] Example 3

[0102] The self-repairing tire inner liner composite material of this embodiment comprises, by weight:

[0103] 50 parts of epoxidized natural rubber;

[0104] 100 parts of epoxidized iron-based combed butadiene-pentadiene rubber;

[0105] 2 parts of ferric chloride;

[0106] 3 parts of dicarboxylic acid suberic acid;

[0107] 80 parts of reinforcing filler carbon black N110;

[0108] 30 parts of paraffin oil plasticizer;

[0109] 5 parts of zinc oxide;

[0110] 3 parts of stearic acid;

[0111] 3 parts sulfur;

[0112] 2 parts of sulfenamide accelerator NS;

[0113] 1 part of imidazole catalyst 1-methylimidazole.

[0114] The epoxidation degree of the epoxidized natural rubber is 40%.

[0115] The number average molecular weight of the epoxidized iron-based combed butadiene rubber is 70w, the epoxidation degree is 10%, and the side group content is 67%; the epoxidized iron-based combed butadiene rubber is an epoxidized iron-based combed butadiene rubber that does not contain gel.

[0116] The raw materials of epoxidized iron-based combed butadiene rubber, i.e., the iron-based combed butadiene rubber, are composed of random copolymers of isoprene and butadiene; the isoprene structure is composed of 3,4-isoprene and 1,4-isoprene; and the butadiene structure is composed of 1,2-butadiene and 1,4-butadiene. The epoxidized iron-based combed butadiene rubber is prepared by coordination polymerization using an iron-based catalyst. During the preparation process, the molar ratio of the monomers butadiene to isoprene is 1:1. The molar content of the butadiene structure in the obtained epoxidized iron-based combed butadiene rubber is 50%, and the molar content of the isoprene structure in the epoxidized iron-based combed butadiene rubber is 50%.

[0117] The molar content of 1,2-butadiene in the butadiene structure of iron-based combed butadiene rubber 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; the molar content of 3,4-isoprene in the isoprene structure of epoxidized iron-based combed butadiene rubber 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.

[0118] The preparation steps are as follows:

[0119] 1) In an internal mixer, epoxidized natural rubber, epoxidized iron-based combed butadiene-pentadiene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer, and reinforcing filler were added and mixed at a filling factor of 0.8. The mixing temperature was 155°C and the mixing time was 180 seconds. After the mixing was completed, a rubber compound was obtained.

[0120] 2) Add the first-stage rubber mix, sulfur, accelerator, and imidazole catalyst into an internal mixer at a mixing temperature of 70°C for 180 seconds to obtain a second-stage rubber mix;

[0121] 3) placing the second-stage rubber mix into a mold for vulcanization at a vulcanization temperature of 130° C. to obtain the tire innerliner composite material.

[0122] Example 4

[0123] This embodiment is substantially the same as embodiment 1, except that the dicarboxylic acid is sebacic acid.

[0124] Example 5

[0125] This embodiment is substantially the same as embodiment 1, except that the dicarboxylic acid is succinic acid.

[0126] Example 6

[0127] This embodiment is substantially the same as embodiment 1, except that the dicarboxylic acid is terephthalic acid.

[0128] Example 7

[0129] This embodiment is substantially the same as embodiment 1, except that the metal salts (ferric chloride and aluminum chloride) are equal in total amount to copper dichloride.

[0130] Comparative Example 1

[0131] This comparative example is basically the same as Example 1, except that the epoxidized natural rubber is replaced by an equal amount of epoxidized iron-based combed butadiene-pentadiene rubber.

[0132] Comparative Example 2

[0133] This comparative example is basically the same as Example 1, except that the epoxidized iron-based combed butadiene-pentadiene rubber is replaced by an equal amount of epoxidized natural rubber.

[0134] Comparative Example 3

[0135] This comparative example is basically the same as Example 1, except that the dicarboxylic acid is replaced by an equal amount of metal salt (the ratio of ferric chloride to aluminum chloride is 1:1).

[0136] Comparative Example 4

[0137] This comparative example is basically the same as Example 1, except that the metal salts (ferric chloride and aluminum chloride) are replaced by an equal amount of dicarboxylic acid.

[0138] Test Example 1

[0139] The properties of the tire inner liner composite material obtained above were tested, and the results are shown in Table 1 below.

[0140] The performance testing contents involved include:

[0141] T90 refers to the time required for the rubber's torque to reach 90% of the maximum torque (MH) during the vulcanization process. The test is carried out using a rotor vulcanizer at a temperature of 160°C.

[0142] The test methods for tensile strength, elongation at break and 300% modulus of elongation refer to GB / T 528-2009 “Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties”;

[0143] The test method for tear strength refers to GB / T 529-2008 "Rubber, vulcanized or thermoplastic rubber - Determination of tear strength (trouser-shaped, right-angled and crescent-shaped test specimens)";

[0144] The fatigue life test method refers to GB / T 1688-2008 "Determination of tensile fatigue of vulcanized rubber", and the strain is set to 100%;

[0145] The test method of gas permeability coefficient refers to GB / T 1038-2000 "Plastic film and sheeting gas permeability test method pressure difference method";

[0146] The self-repair performance test is carried out using Figure 1 The puncture object shown punctured the sample. In order to accelerate the self-repair speed, the punctured sample was placed in a 60°C oven. After being taken out, the tensile strength and gas permeability coefficient of the punctured part were tested.

[0147] Table 1

[0148]

[0149] Table 1 continued

[0150]

[0151] According to the results in Table 1, Examples 1 to 7 demonstrate the mechanical properties, air tightness, and self-repairing properties of tire innerliner composite materials under different rubber ratios, different crosslinking agent dosages, and different filler filling amounts.

[0152] Examples 1, 4, and 5 demonstrate that long-chain dicarboxylic acids as crosslinkers can improve the material's tensile properties, tear resistance, fatigue resistance, air tightness, and self-repair rate. The dicarboxylic acid used in Example 6 contains a benzene ring structure, which improves the material's tensile properties, resulting in a significant increase in tensile strength, but also a significant decrease in fatigue resistance. Examples 1 and 7 demonstrate that trivalent metal salts significantly improve tensile properties and self-repair rate compared to divalent metal salts.

[0153] Comparative Example 1 shows that using only epoxidized iron-based combed butadiene-pentadiene rubber as a matrix significantly improves the material's airtightness, but its mechanical properties deteriorate significantly. Comparative Example 2 shows that using only epoxidized natural rubber as a matrix exhibits excellent mechanical properties, but its airtightness is poor. Comparative Examples 3 and 4 demonstrate that using only a single crosslinker results in a long self-healing time and poor post-healing performance. However, the combined use of metal salts and dicarboxylic acids in the examples demonstrated a significant synergistic effect.

[0154] The foregoing is merely an embodiment of the present application, and the scope of protection 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, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the technical ideas and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A self-repairing tire inner liner composite material, characterized in that: The tire inner liner composite material comprises, by weight: 10-50 parts of epoxidized natural rubber; Epoxy iron-based combed butadiene-pentadiene rubber 50-100 parts; 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 epoxidized iron-based combed butadiene rubber has a number average molecular weight of 30-90w and a degree of epoxidation of 10-30%. The epoxidized iron-based combed butadiene rubber is obtained by epoxidation modification of the iron-based combed butadiene rubber. The iron-based combed butadiene rubber is composed of a random copolymer of isoprene and butadiene, with a side group content of 60-80%. The isoprene includes 3,4-isoprene and 1,4-isoprene, and the butadiene includes 1,2-butadiene and 1,4-butadiene. The epoxidation degree of the epoxidized natural rubber is 20-40%; The metal salt is one or both of ferric chloride and aluminum chloride; The dicarboxylic acid is one or more of pimelic acid, suberic acid, azelaic acid, and sebacic acid.

2. The self-repairing tire inner liner composite material according to claim 1, characterized in that: The epoxidized iron-based combed butadiene-vinyl rubber is obtained by epoxidizing the iron-based combed butadiene-vinyl rubber through one or more of hydrogen peroxide, peroxyformic acid or peracetic acid.

3. The self-repairing tire inner liner composite material according to claim 2, characterized in that: The epoxidized iron-based combed butadiene-pentadiene rubber is an epoxidized iron-based combed butadiene-pentadiene rubber that does not contain gel.

4. The self-repairing tire inner liner composite material according to claim 1, 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%.

5. The self-repairing tire inner liner 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, and N330; and / or, The plasticizer is one or more of aromatic oil, naphthenic oil, paraffin oil, DOP, and DBP; and / or The accelerator is a sulfenamide accelerator; and / or, The imidazole catalyst is one or both of 1-methylimidazole and 2-ethyl-4-methylimidazole.

6. The method for preparing the composite material for a tire inner liner according to any one of claims 1 to 5, wherein: The preparation method comprises the following steps: 1) In an internal mixer, epoxidized natural rubber, epoxidized iron-based combed butadiene-pentadiene rubber, metal salt, dicarboxylic acid, zinc oxide, stearic acid, plasticizer, and reinforcing filler are added and mixed at a filling factor of 0.6-0.

8. The mixing temperature is 135-155°C and the mixing time is 180-360 seconds. After mixing, a rubber compound is obtained. 2) Add the first-stage rubber mix, sulfur, accelerator, and imidazole catalyst into an internal mixer at a mixing temperature of 70-80°C for 120-180 seconds to obtain a second-stage rubber mix; 3) placing the second-stage rubber mix into a mold for vulcanization at a vulcanization temperature of 130-160° C. to obtain the tire innerliner composite material.

7. Use of the tire inner liner composite material according to any one of claims 1 to 5 in tires, wherein the composite material is used for the inner liner of passenger car tires, motorcycle tires and truck tires.

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