A reactive self-repairing rubber composition, a preparation method thereof and a self-repairing tire
The self-healing rubber composition, which utilizes chemical anchoring and physical entanglement networks, solves the problems of plasticizer migration and high-speed creep, achieving stability and self-healing efficiency at high temperatures and speeds, thus extending tire lifespan and ensuring safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG CENWAY MATERIALS CO LTD
- Filing Date
- 2026-04-13
- Publication Date
- 2026-06-12
AI Technical Summary
Existing self-healing sealing layer materials pose risks of plasticizer migration and high-speed centrifugal creep during long-term use, leading to tire structural instability and failure of self-healing function.
A self-healing rubber composition with no significant plasticizer migration and excellent high-temperature resistance to centrifugal creep was constructed by co-curing reactive liquid butyl rubber with halogenated butyl rubber and using a dual locking network of chemical anchoring and physical entanglement.
It achieves material stability and self-healing efficiency under high temperature and high speed conditions, avoids plasticizer migration, and ensures long tire life and safety.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of rubber composition technology, and in particular to a reactive self-healing rubber composition, its preparation method, and a self-healing tire. Background Technology
[0002] As the automotive industry transforms towards electrification and intelligentization, tire maintenance-free operation has become a core requirement. Self-sealing tires, as an active safety technology, utilize a highly viscoelastic sealing material on the inner surface of the tire. This material's fluidity and adhesion allow it to instantly seal the puncture after being punctured by a sharp object. This mechanism effectively avoids the risk of tire blowouts caused by sudden pressure drops, which is crucial for ensuring high-speed driving safety. Currently, most self-sealing sealing layer materials use butyl rubber as the base material, supplemented with plasticizers, to achieve the required wetting properties and sealing efficiency.
[0003] However, existing self-healing sealant technologies (especially oil-based systems) have significant drawbacks in practical applications, with plasticizer migration being a key bottleneck limiting their long-term reliability. Traditional systems typically rely heavily on large amounts of mineral oil or low-molecular-weight polyisobutylene (PIB) and other small-molecule substances to achieve sufficient viscosity. During long-term tire service, especially under conditions of high summer temperatures or prolonged driving, these small molecules easily penetrate and migrate into the tire's inner liner (airtight layer). This migration process not only causes swelling and delamination of the inner liner, compromising the overall structural stability of the tire, but also causes the sealant to gradually harden and dry out due to the loss of plasticizers, ultimately leading to the loss of its self-healing function.
[0004] Meanwhile, high-speed centrifugal creep is also a major technical obstacle hindering the development of high-performance self-sealing tires. When a vehicle travels at high speed, the tire rotates at extremely high speeds, and the internal sealing layer material is subjected to enormous centrifugal forces, with local accelerations often exceeding 200g. Under such a strong force field, the low-modulus sealing layer material is prone to macroscopic flow and deformation, leading to uneven accumulation of rubber compound towards the center of the tire crown. This physical displacement of the material severely disrupts the tire's initial dynamic balance, causing severe vibrations and noise, significantly affecting the vehicle's ride comfort and handling safety.
[0005] From a materials design perspective, self-healing sealing layers face a severe challenge in balancing dynamic performance. To effectively seal punctures, the material needs to possess liquid-like fluidity and adhesion at the microscopic level; conversely, to maintain shape stability under high-speed centrifugal conditions, it must exhibit solid-like structural strength and creep resistance at the macroscopic level. Traditional oil-based stretching techniques primarily adjust viscoelasticity by physically filling low-molecular-weight substances. However, lacking an effective structural locking mechanism, these techniques struggle to simultaneously meet these two extreme performance requirements under complex dynamic conditions. Therefore, developing a novel self-healing rubber material that completely eliminates plasticizer migration while possessing excellent high-temperature centrifugal creep resistance has become a pressing technical challenge in the field of safety tires. Summary of the Invention
[0006] The purpose of this invention is to provide a reactive self-healing rubber composition, its preparation method, and a self-healing tire, which solves at least one of the above-mentioned technical problems. By constructing a dual locking network of physical entanglement and chemical anchoring, it achieves a self-healing rubber composition with no significant plasticizer migration and excellent high-temperature resistance to centrifugal creep, as well as a safety tire using this composition as a sealing layer, fundamentally solving the problems of oil leakage and dynamic balance failure in the actual use of self-healing tires.
[0007] The embodiments of the present invention are implemented as follows: A reactive self-healing rubber composition comprising the following components in parts by weight: 100 parts of halogenated butyl rubber.
[0008] 20-80 parts of reactive liquid butyl rubber.
[0009] 0.1 to 5 parts of the vulcanization crosslinking system.
[0010] 30-60 parts of reinforcing agent.
[0011] 10-30 parts of tackifying resin.
[0012] The reactive liquid butyl rubber has a molecular weight higher than its critical entanglement molecular weight. Furthermore, the liquid rubber possesses reactive properties, with a weight-average molecular weight ranging from 20,000 g / mol to 40,000 g / mol.
[0013] The reactive liquid butyl rubber contains isoprene structural units, and the molar fraction of the isoprene structural units is between 0.5% and 2.5%.
[0014] In a preferred embodiment of the present invention, in the above-mentioned reactive self-healing rubber composition, The halogenated butyl rubber is brominated butyl rubber BIIR, which has a Mooney viscosity ML1+8 of 30 to 50 at 125°C.
[0015] In a preferred embodiment of the present invention, in the above-mentioned reactive self-healing rubber composition, In each component, the content of mineral oil and polyisobutylene plasticizer with a weight average molecular weight of less than 5000 g / mol is less than 1 part.
[0016] In a preferred embodiment of the present invention, in the above-mentioned reactive self-healing rubber composition, The halogenated butyl rubber is brominated butyl rubber.
[0017] In a preferred embodiment of the present invention, in the above-mentioned reactive self-healing rubber composition, The vulcanization crosslinking system includes at least one of zinc oxide and sulfur.
[0018] In a preferred embodiment of the present invention, in the above-mentioned reactive self-healing rubber composition, The reinforcing agent used is carbon black N660.
[0019] A method for preparing a reactive self-healing rubber composition, comprising: S100 involves adding halogenated butyl rubber, reinforcing agents, and tackifying resins into a mixing equipment and mixing them at high temperature to obtain a pre-filled masterbatch.
[0020] S200: After cooling the prefilled masterbatch, add it to the vulcanization crosslinking system for refining to make the vulcanization system evenly dispersed, thus obtaining a sulfur-containing intermediate rubber compound.
[0021] S300, the sulfur-containing intermediate rubber compound and reactive liquid butyl rubber are mixed at high temperature in an extrusion device to induce a co-vulcanization reaction between the reactive liquid butyl rubber and the halogenated butyl rubber, thereby obtaining a reactive self-healing rubber composition.
[0022] The reactive self-healing rubber composition is the reactive self-healing rubber composition as described above.
[0023] In a preferred embodiment of the present invention, in the preparation method of the above-mentioned reactive self-healing rubber composition, In S100, the rotor speed of the high-temperature mixing is 60 rpm, the initial temperature is 60℃, and the mixing temperature rises to 110℃~130℃.
[0024] In S200, the vulcanization crosslinking system is added when the temperature of the prefilled masterbatch drops below 60°C, and the mixture is passed through a thin tube 5 to 8 times.
[0025] In S300, the extrusion equipment is a twin-screw extruder, and the mixing temperature is controlled between 130℃ and 180℃.
[0026] A self-healing tire includes a tread, a carcass, an inner liner, and a sealing layer, the sealing layer being adhered to the inner surface of the inner liner, characterized in that the sealing layer is made by vulcanization of the reactive self-healing rubber composition as described above.
[0027] The beneficial effects of the embodiments of the present invention are: This invention utilizes a chemical anchoring and locking mechanism, employing reactive liquid butyl rubber containing a specific proportion of isoprene structural units, to co-vulcanize with a halogenated butyl rubber matrix during the vulcanization stage. Because the liquid rubber molecules are chemically bonded to a cross-linked network forming dangling chains—meaning one end of the liquid rubber is connected to the network through vulcanization while the other end freely oscillates to provide viscosity—its diffusion coefficient approaches zero. This fundamentally solves the problem of plasticizers or inactive liquid rubber easily migrating and precipitating into the tire's inner liner or outer tread in traditional sealing materials. Experiments show that no grease seepage occurred during long-term contact testing at 80°C, significantly extending tire lifespan and ensuring a clean appearance.
[0028] This invention utilizes the principle of physical entanglement locking to control the weight-average molecular weight of reactive liquid butyl rubber to 20,000 g / mol to 40,000 g / mol, a range higher than its critical entanglement molecular weight. Even under dynamic conditions, the physical entanglement formed between molecular chains provides basic yield strength. Combined with a chemical cross-linking network, this composition maintains the stability of the sealing layer shape under high temperature and high centrifugal force conditions, effectively reducing dynamic balance changes and preventing tire vibration caused by material accumulation.
[0029] Although the liquid rubber is anchored within the network, its long chain ends retain a high degree of local freedom, allowing the material to quickly wet the anchor or fill the puncture upon impact. The sealing layer prepared by this invention can repeatedly seal large punctures up to 6 mm in diameter and maintains good airtightness after repeated nail insertions and removals. Simultaneously, by limiting the content of small-molecule mineral oil in the system, excessive reduction of the rubber's viscosity by oily substances is avoided, ensuring the sealing strength after repair.
[0030] The preparation method of this invention achieves precise control of the reaction degree through a process path of pre-filled masterbatch compounding and twin-screw extrusion-induced co-vulcanization. Inducing in-situ reaction in the extrusion stage ensures uniform bonding between the liquid rubber and the matrix. Furthermore, this invention reduces the use of low-molecular-weight plasticizers, which have potential negative environmental impacts in traditional formulations, aligning with the industrial trend of green manufacturing. Detailed Implementation
[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown herein can generally be arranged and designed in various different configurations.
[0032] The first embodiment of the present invention provides a reactive self-healing rubber composition comprising the following components in parts by weight: 100 parts of halogenated butyl rubber; 20-80 parts of reactive liquid butyl rubber; 0.1-5 parts of a vulcanization crosslinking system; 30-60 parts of a reinforcing agent; and 10-30 parts of a tackifying resin; wherein the reactive liquid butyl rubber has a molecular weight higher than its critical entanglement molecular weight. The reactive liquid rubber has a weight-average molecular weight of 20,000 g / mol to 40,000 g / mol; the reactive liquid butyl rubber contains isoprene structural units, and the molar fraction of the isoprene structural units is 0.5% to 2.5%.
[0033] In a preferred embodiment of the present invention, the halogenated butyl rubber in the above-mentioned reactive self-healing rubber composition is brominated butyl rubber BIIR, which has a Mooney viscosity ML1+8 of 30 to 50 at 125°C.
[0034] In a preferred embodiment of the present invention, in the above-mentioned reactive self-healing rubber composition, the content of mineral oil and polyisobutylene plasticizer with a weight average molecular weight of less than 5000 g / mol is less than 1 part in each component.
[0035] In a preferred embodiment of the present invention, the halogenated butyl rubber in the above-mentioned reactive self-healing rubber composition is brominated butyl rubber.
[0036] In a preferred embodiment of the present invention, the vulcanization crosslinking system in the above-mentioned reactive self-healing rubber composition includes at least one of zinc oxide and sulfur.
[0037] In a preferred embodiment of the present invention, the reinforcing agent in the above-mentioned reactive self-healing rubber composition is carbon black N660.
[0038] A second embodiment of the present invention provides a method for preparing a reactive self-healing rubber composition, comprising: S100, adding halogenated butyl rubber, reinforcing agent and tackifying resin into a mixing device and mixing at high temperature to obtain a pre-filled masterbatch; S200, cooling the pre-filled masterbatch and adding it to a vulcanization crosslinking system for re-mixing to make the vulcanization system uniformly dispersed to obtain a sulfur-containing intermediate rubber compound; S300, mixing the sulfur-containing intermediate rubber compound and reactive liquid butyl rubber at high temperature in an extrusion device to induce a co-vulcanization reaction between the reactive liquid butyl rubber and the halogenated butyl rubber to obtain a reactive self-healing rubber composition; the reactive self-healing rubber composition is the reactive self-healing rubber composition as described above.
[0039] In a preferred embodiment of the present invention, in the preparation method of the above-mentioned reactive self-healing rubber composition, in S100, the rotor speed of the high-temperature mixing is 60 rpm, the initial temperature is 60°C, and the mixing temperature is raised to 110°C to 130°C; in S200, the vulcanization crosslinking system is added when the temperature of the prefilled masterbatch drops below 60°C, and the mixture is passed through 5 to 8 times; in S300, the extrusion equipment is a twin-screw extruder, and the mixing temperature is controlled at 130°C to 180°C.
[0040] After vulcanization, the reactive self-healing rubber composition was tested at 70°C and 300Pa constant shear stress for 2 hours, and its shear creep strain was less than 5%. When placed on the surface of qualitative filter paper at 80°C for 168 hours, the oil absorption weight gain of the filter paper was less than 0.1%.
[0041] A third embodiment of the present invention provides a self-healing tire, which includes a tread, a carcass, an inner liner, and a sealing layer, wherein the sealing layer is adhered to the inner surface of the inner liner, characterized in that the sealing layer is made by vulcanization of the reactive self-healing rubber composition as described above.
[0042] In the following examples, the content of each component is expressed as parts by mass, without specifying a particular mass, as long as the mass ratio is met. The formulations of each example are shown in Table 1.
[0043] Table 1: Specific component ratios (by weight) of the embodiments and comparative examples of the present invention
[0044] (I) Example 1: 100 parts of brominated butyl rubber, 45 parts of carbon black N660, and 20 parts of tackifying resin were added to an internal mixer. The rotor speed was set to 60 rpm and the initial temperature to 60°C. The mixture was then discharged after the temperature reached 110°C to 130°C to obtain the pre-filled masterbatch.
[0045] The pre-filled masterbatch is cooled on a two-roll mill until the temperature drops below 60°C. Then, 3.0 parts zinc oxide, 0.5 parts sulfur, and 1.0 part accelerator MBTS are added and the mixture is re-rolled. The mixture is then passed through a thin mill 5-8 times to ensure uniform dispersion of the vulcanization system, resulting in a sulfur-containing intermediate rubber compound.
[0046] The sulfur-containing intermediate rubber compound was mixed with 40 parts of reactive liquid butyl rubber (Mw≈36k) in a twin-screw extruder. The mixing temperature was controlled at 130℃~180℃ to induce a co-vulcanization reaction between the liquid butyl rubber and the matrix, resulting in a self-healing rubber composition.
[0047] (II) Example 2: 100 parts of brominated butyl rubber, 45 parts of carbon black N660, and 20 parts of tackifying resin were added to an internal mixer. The rotor speed was set to 60 rpm and the initial temperature to 60°C. The mixture was then discharged after the temperature reached 110°C to 130°C to obtain the pre-filled masterbatch.
[0048] The pre-filled masterbatch is cooled on a two-roll mill until the temperature drops below 60°C. Then, 3.0 parts zinc oxide, 0.5 parts sulfur, and 1.0 part accelerator MBTS are added and the mixture is re-rolled. The mixture is then passed through a thin mill 5-8 times to ensure uniform dispersion of the vulcanization system, resulting in a sulfur-containing intermediate rubber compound.
[0049] A self-healing rubber composition was obtained by mixing a sulfur-containing intermediate rubber compound with 60 parts of reactive liquid butyl rubber (Mw≈36k) in a twin-screw extruder at 130℃~180℃.
[0050] (III) Example 3: 100 parts of brominated butyl rubber, 45 parts of carbon black N660, and 20 parts of tackifying resin were added to an internal mixer. The rotor speed was set to 60 rpm and the initial temperature to 60°C. The mixture was then discharged after the temperature reached 110°C to 130°C to obtain the pre-filled masterbatch.
[0051] The pre-filled masterbatch is cooled on a two-roll mill until the temperature drops below 60°C. Then, 3.0 parts zinc oxide, 0.8 parts sulfur, and 1.2 parts MBTS accelerator are added and the mixture is re-rolled. The mixture is then passed through a thin mill 5-8 times to ensure uniform dispersion of the vulcanization system, resulting in a sulfur-containing intermediate rubber compound.
[0052] A self-healing rubber composition was obtained by mixing sulfur-containing intermediate rubber compound with 80 parts of reactive liquid butyl rubber (Mw≈36k) in a twin-screw extruder at 130℃~180℃.
[0053] (iv) Comparative Example 1: 100 parts of brominated butyl rubber, 45 parts of carbon black N660, and 20 parts of tackifying resin were added to an internal mixer. The rotor speed was set to 60 rpm and the initial temperature to 60°C. The mixture was then discharged after the temperature reached 110°C to 130°C to obtain the pre-filled masterbatch.
[0054] The pre-filled masterbatch is cooled on a two-roll mill until the temperature drops below 60°C. Then, 3.0 parts zinc oxide, 0.5 parts sulfur, and 1.0 part accelerator MBTS are added and the mixture is re-rolled. The mixture is then passed through a thin mill 5-8 times to ensure uniform dispersion of the vulcanization system, resulting in a sulfur-containing intermediate rubber compound.
[0055] The sulfur-containing intermediate rubber compound was mixed with 40 parts of naphthenic oil in a twin-screw extruder. Since naphthenic oil is non-reactive, it primarily functions as a physical diluent.
[0056] (v) Comparative Example 2: 100 parts of brominated butyl rubber, 45 parts of carbon black N660, and 20 parts of tackifying resin were added to an internal mixer. The rotor speed was set to 60 rpm and the initial temperature to 60°C. The mixture was then discharged after the temperature reached 110°C to 130°C to obtain the pre-filled masterbatch.
[0057] The pre-filled masterbatch is cooled on a two-roll mill until the temperature drops below 60°C. Then, 3.0 parts zinc oxide, 0.5 parts sulfur, and 1.0 part accelerator MBTS are added and the mixture is re-rolled. The mixture is then passed through a thin mill 5-8 times to ensure uniform dispersion of the vulcanization system, resulting in a sulfur-containing intermediate rubber compound.
[0058] The sulfur-containing intermediate rubber compound was mixed with 40 parts of polyisobutylene (PIB, Mw≈2400) in a twin-screw extruder.
[0059] (vi) Performance testing: (1) Shear creep test: Using a rheometer, a constant shear stress of 300 Pa is applied at 70°C, and the cumulative deformation (CreepStrain) is recorded after 2 hours.
[0060] (2) Migration test: A circular vulcanized rubber sheet with a diameter of 20 mm was placed between qualitative filter papers, a 2 kg counterweight was applied, and it was placed in an 80℃ oven for 168 hours. The oil absorption weight gain rate was calculated by weighing the difference in weight of the filter paper before and after.
[0061] (3) Self-healing performance test: the sealing layer is pasted on the surface of the butyl inner liner, pierced with a 6mm diameter steel nail and pulled out, and the hole sealing is observed at 23℃ and 80℃.
[0062] (4) Dynamic balance stability test: The composition is processed into a 4mm thick sealing layer and coated on the inner surface of a 205 / 55R16 tire. The tire is driven continuously at 120km / h for 24 hours, and the increase in dynamic balance mass deviation before and after driving is tested.
[0063] Table 2: Overall performance test results of each embodiment and comparative example
[0064] The performance test results are shown in Table 2.
[0065] Excellent creep resistance: The shear creep of Examples 1-3 was controlled within 5% (2.8%-4.8%), significantly better than Comparative Example 1 (19.2%) and Comparative Example 2 (13.5%). This confirms that when the molecular weight of the liquid rubber is higher than the critical entanglement molecular weight (Mc≈20,000g / mol), it can effectively construct a physical entanglement network, providing basic yield strength to resist high-temperature centrifugal creep.
[0066] Completely solves the migration problem (zero migration): The filter paper migration weight gain rate in the example is extremely low (maximum only 0.05%), close to 0, while Comparative Example 1, due to the use of non-reactive naphthenic oil, has a migration rate as high as 6.50%. This indicates that through a chemical anchoring and locking mechanism, the isoprene double bonds on the reactive liquid butyl rubber are co-vulcanized with the matrix rubber, fixing the liquid molecules to the cross-linked network by chemical bonds, thus completely eliminating exudation.
[0067] Stability under high-speed conditions: Real-world tire driving tests showed that the increase in dynamic balance deviation in the embodiments was less than 10g (3g-8g), while that in Comparative Example 1 was as high as 52g. This indicates that the composition prepared in this invention did not undergo displacement under high-speed centrifugal force, meeting the stringent requirements for dynamic balance and NVH in high-end new energy vehicles.
[0068] High self-healing efficiency: The example maintained a 100% sealing success rate at 80°C, while the comparative example showed a significant decrease in success rate (85%-90%) at high temperatures. This is attributed to the local degrees of freedom at the ends of the long chains of the liquid rubber, which allows the material to maintain excellent wettability and adhesion while possessing structural strength.
[0069] In summary, the present invention utilizes a dual-locking structure constructed from reactive liquid butyl rubber of a specific molecular weight, which achieves zero migration and extremely high high-temperature resistance to centrifugal creep while ensuring high self-healing efficiency.
[0070] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.
Claims
1. A reactive self-healing rubber composition, characterized in that, Includes the following components in parts by weight: 100 parts of halogenated butyl rubber; 20-80 parts of reactive liquid butyl rubber; 0.1–5 parts of the vulcanization crosslinking system; 30-60 parts of reinforcing agent; 10-30 parts of tackifying resin; The weight-average molecular weight of the reactive liquid butyl rubber is between 20,000 g / mol and 40,000 g / mol. The reactive liquid butyl rubber contains isoprene structural units, and the molar fraction of the isoprene structural units is between 0.5% and 2.5%.
2. The reactive self-healing rubber composition according to claim 1, characterized in that, The halogenated butyl rubber is brominated butyl rubber BIIR, which has a Mooney viscosity ML1+8 of 30 to 50 at 125°C.
3. The reactive self-healing rubber composition according to claim 1, characterized in that, In each component, the content of mineral oil and polyisobutylene plasticizer with a weight average molecular weight of less than 5000 g / mol is less than 1 part.
4. The reactive self-healing rubber composition according to claim 1, characterized in that, The halogenated butyl rubber is brominated butyl rubber.
5. The reactive self-healing rubber composition according to claim 1, characterized in that, The vulcanization crosslinking system includes at least one of zinc oxide and sulfur.
6. The reactive self-healing rubber composition according to claim 1, characterized in that, The reinforcing agent used is carbon black N660.
7. A method for preparing a reactive self-healing rubber composition, characterized in that, include: S100 involves adding halogenated butyl rubber, reinforcing agent, and tackifying resin into a mixing equipment and mixing them at high temperature to obtain a pre-filled masterbatch. S200, after cooling the prefilled masterbatch, it is added to the vulcanization crosslinking system for refining to obtain a sulfur-containing intermediate rubber compound; S300, the sulfur-containing intermediate rubber compound and reactive liquid butyl rubber are mixed at high temperature in an extrusion device to induce the reactive liquid butyl rubber and the halogenated butyl rubber to undergo a co-vulcanization reaction to obtain a reactive self-healing rubber composition. The reactive self-healing rubber composition is the reactive self-healing rubber composition as described in any one of claims 1-6.
8. The method for preparing the reactive self-healing rubber composition according to claim 1, In S100, the rotor speed of the high-temperature mixing is 60 rpm, the initial temperature is 60°C, and the mixing temperature rises to 110°C to 130°C. In S200, the vulcanization crosslinking system is added when the temperature of the prefilled masterbatch drops below 60°C, and the mixture is passed through a thin tube 5 to 8 times. In S300, the extrusion equipment is a twin-screw extruder, and the mixing temperature is controlled between 130℃ and 180℃.
9. A self-sealing tire, comprising a tread, a carcass, an inner liner, and a sealing layer, wherein the sealing layer is adhered to the inner surface of the inner liner, characterized in that, The sealing layer is made by vulcanization of the reactive self-healing rubber composition according to any one of claims 1 to 6.