A high-damping, high-airtightness rubber composition, its preparation method and application

Abstract

This invention discloses a high-damping, high-airtightness rubber composition, its preparation method, and its application, comprising the following components by weight: 100 parts of halogenated butyl rubber; 10-30 parts of liquid butyl rubber; 30-80 parts of reinforcing agent; 1.3-6 parts of vulcanization system; and 4-13 parts of processing aid. The liquid butyl rubber is a copolymer of isobutylene and conjugated diene, with a weight-average molecular weight of 10,000 g / mol to 50,000 g / mol, and the content of structural units from conjugated diene in the liquid butyl rubber is 0.5 mol% to 4 mol%. The content of mineral oil plasticizer in each component is less than 2 parts. By introducing liquid butyl rubber with a specific molecular weight range and a vulcanizable unsaturated structure into the halogenated butyl rubber, effective suppression of tire cavity resonance noise is achieved.

Description

Technical Field

[0001] This invention relates to the field of rubber composition technology, and in particular to a high-damping, high-airtightness rubber composition, its preparation method, and its application. Background Technology

[0002] As automotive powertrains move towards electrification, internal combustion engine noise has significantly decreased during vehicle operation. Noise generated by tires during driving, especially tire cavity resonance noise (typically concentrated in the 200–250 Hz frequency range), is gradually becoming one of the main sources of noise inside the vehicle. Simultaneously, electric vehicles are highly sensitive to driving range, requiring tires to have their inner liner thickness reduced as much as possible while maintaining airtightness, in order to reduce tire weight and rolling resistance.

[0003] In existing technologies, tire inner linings typically use halogenated butyl rubber combined with mineral oil plasticizers to improve processing performance. However, the introduction of mineral oil significantly increases the free volume of the material system, leading to a decrease in gas barrier properties. Furthermore, mineral oil is prone to migration and volatilization during long-term use, resulting in interfacial contamination and performance degradation. Therefore, achieving a 'decoupling' improvement of high-frequency damping performance and ultra-low gas permeability is a key technical challenge in this field.

[0004] To reduce tire cavity noise, most existing electric vehicle tires use polyurethane sound-absorbing cotton pasted on the inner wall of the tire for acoustic absorption. However, this solution has problems such as added weight, difficulty in dynamic balance control, and the possibility of sound-absorbing material falling off during service, affecting the reliability and safety of the tire.

[0005] In addition, some existing technologies form a viscous sealing layer by introducing a large amount of low-molecular-weight polyisobutylene into butyl rubber. The main purpose of this is to achieve the self-repair function of the tire. Such materials usually have the characteristics of low modulus and high fluidity, which makes it difficult to meet the mechanical performance and long-term stability requirements of the tire inner liner as a structural airtight layer.

[0006] Therefore, there is an urgent need for a new material solution that can achieve both high airtightness and high acoustic damping performance while maintaining the structural integrity and manufacturability of the tire inner liner. Summary of the Invention

[0007] The present invention aims to provide a high-damping, high-airtightness rubber composition, its preparation method, and its applications, to solve at least one of the aforementioned technical problems. It involves introducing liquid butyl rubber with a specific molecular weight range and a vulcanizable unsaturated structure into halogenated butyl rubber, and co-curing the low-molecular-weight liquid butyl rubber containing double bonds with the matrix rubber. In the crosslinked network, one or more ends of the liquid butyl rubber are locked onto the main grid, forming a large number of confined suspended chains. These suspended chains undergo intramolecular friction in a specific frequency band of 200-250Hz, generating efficient energy dissipation, thereby achieving precise noise reduction. Simultaneously, due to the excellent structural homology between the liquid butyl rubber and the matrix, it not only does not increase the free volume but also fills the micropores of the matrix through molecular chain entanglement, achieving a reverse improvement in airtightness. The significant improvement in the material's airtightness allows for a thinner tire inner liner, thus balancing the tire's noise reduction performance, airtightness, and engineering applicability.

[0008] The embodiments of the present invention are implemented as follows:

[0009] A high-damping, high-airtightness rubber composition comprising the following components in parts by weight:

[0010] 100 parts of halogenated butyl rubber.

[0011] 10-30 parts of liquid butyl rubber.

[0012] 30-80 parts of reinforcing agent.

[0013] Vulcanization system: 1.3 to 6 parts.

[0014] Processing aids: 4-13 parts.

[0015] The liquid butyl rubber is a copolymer of isobutylene and conjugated diene, with a weight-average molecular weight of 10,000 g / mol to 50,000 g / mol, and the content of structural units from conjugated diene in the liquid butyl rubber is 0.5 mol% to 4 mol.

[0016] The liquid butyl rubber is co-vulcanized with the halogenated butyl rubber matrix through unsaturated double bonds in its structure to form a cross-linked network containing a suspended chain structure.

[0017] The content of mineral oil plasticizer in each component is less than 2 parts.

[0018] In a preferred embodiment of the present invention, in the above-mentioned high-damping, high-airtightness rubber composition,

[0019] The liquid butyl rubber has a weight-average molecular weight of 25,000 g / mol to 45,000 g / mol and a content of 15 to 25 parts.

[0020] In a preferred embodiment of the present invention, in the above-mentioned high-damping, high-airtightness rubber composition,

[0021] The halogenated butyl rubber includes at least one of brominated butyl rubber and chlorinated butyl rubber.

[0022] In a preferred embodiment of the present invention, in the above-mentioned high-damping, high-airtightness rubber composition,

[0023] The reinforcing agent used is carbon black N660.

[0024] In a preferred embodiment of the present invention, in the above-mentioned high-damping, high-airtightness rubber composition,

[0025] The sulfidation system includes at least one of zinc oxide and sulfur.

[0026] The zinc oxide content is 1 to 5 parts, and the sulfur content is 0.3 to 1 part.

[0027] In a preferred embodiment of the present invention, in the above-mentioned high-damping, high-airtightness rubber composition,

[0028] The processing aids include at least one of stearic acid and C5 resin.

[0029] The content of stearic acid is 1 to 3 parts, and the content of C5 resin is 3 to 10 parts.

[0030] A method for preparing a high-damping, high-airtightness rubber composition, comprising:

[0031] S100: Liquid butyl rubber and halogenated butyl rubber are uniformly mixed to obtain a masterbatch containing liquid butyl rubber.

[0032] S200, the masterbatch is mixed with a reinforcing agent, a vulcanization system, and processing aids, and then vulcanized to obtain the target rubber composition. The high-damping, high-airtightness rubber composition is the rubber composition described above.

[0033] In a preferred embodiment of the present invention, in the preparation method of the above-mentioned high-damping and high-airtightness rubber composition, the mixing method in S100 is liquid phase mixing, in which liquid butyl rubber is dissolved in an organic solvent to form a first solution, which is then introduced into the halogenated butyl rubber solution for mixing, and the masterbatch is obtained after solvent removal treatment.

[0034] An electric vehicle tire, the tire comprising an inner liner made of the rubber composition as described above.

[0035] In a preferred embodiment of the present invention, the thickness of the inner liner layer in the electric vehicle tire is no greater than 0.9 mm.

[0036] The beneficial effects of the embodiments of the present invention are:

[0037] The high-damping, high-airtightness rubber composition of the present invention introduces liquid butyl rubber with a specific molecular weight range and a vulcanizable unsaturated structure into halogenated butyl rubber, thereby constructing a highly efficient energy dissipation structure within the material matrix. This effectively suppresses cavity resonance noise in electric vehicle tires without the need for external sound-absorbing materials. Because the liquid butyl rubber and the halogenated butyl rubber matrix have a highly compatible polyisobutylene backbone structure, the gas barrier properties of the material are significantly improved, allowing for a reduction in the thickness of the tire inner liner. This system-wide approach balances quietness, airtightness, and tire rolling performance.

[0038] By introducing co-vulcanizable liquid butyl rubber to replace the traditional mineral oil plasticizing system, the internal plasticizing and internal damping of the rubber system are synergistically regulated, avoiding the migration of low-molecular-weight plasticizers. The liquid butyl rubber forms a large number of suspended chain structures in the vulcanization network, which significantly improves the energy dissipation capacity of the material in the resonant frequency band of the tire cavity. Since the liquid butyl rubber and the matrix halogenated butyl rubber have the same polyisobutylene main chain structure, the free volume of the material is reduced, and the gas barrier performance is significantly improved, so that the thickness of the tire inner liner can be reduced to 0.6–0.7 mm. Through the system design of high material damping and structural thinning, the acoustic performance is improved without significantly increasing the overall rolling resistance of the tire. Detailed Implementation

[0039] 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. 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.

[0040] The first embodiment of the present invention provides a high-damping, high-airtightness rubber composition comprising the following components by weight: 100 parts of halogenated butyl rubber; 10-30 parts of liquid butyl rubber; 30-80 parts of reinforcing agent; 1.3-6 parts of vulcanization system; and 4-13 parts of processing aid. The liquid butyl rubber is a copolymer of isobutylene and conjugated diene, with a weight-average molecular weight of 10,000 g / mol to 50,000 g / mol. The content of structural units derived from conjugated diene in the liquid butyl rubber is 0.5 mol% to 4 mol%. The liquid butyl rubber is co-vulcanized with the halogenated butyl rubber matrix through unsaturated double bonds in its structure to form a cross-linked network containing a suspended chain structure. The content of mineral oil plasticizer in each component is less than 2 parts.

[0041] In the system of this invention, since liquid butyl rubber also has the function of internal plasticizing, there is no need to add mineral oil, thereby avoiding the deterioration of air tightness caused by the increase of free volume.

[0042] In a preferred embodiment of the present invention, in the above-mentioned high-damping and high-airtightness rubber composition, the liquid butyl rubber has a weight-average molecular weight of 25,000 g / mol to 45,000 g / mol and a content of 15 to 25 parts.

[0043] In a preferred embodiment of the present invention, the halogenated butyl rubber in the above-mentioned high-damping and high-airtightness rubber composition includes at least one of brominated butyl rubber and chlorinated butyl rubber.

[0044] In a preferred embodiment of the present invention, the reinforcing agent in the above-mentioned high-damping and high-airtightness rubber composition is carbon black N660.

[0045] In a preferred embodiment of the present invention, the vulcanization system in the above-mentioned high-damping and high-airtightness rubber composition includes at least one of zinc oxide and sulfur; the content of zinc oxide is 1 to 5 parts, and the content of sulfur is 0.3 to 1 part.

[0046] In a preferred embodiment of the present invention, the processing aid in the above-mentioned high-damping and high-airtightness rubber composition includes at least one of stearic acid and C5 resin; the content of stearic acid is 1 to 3 parts, and the content of C5 resin is 3 to 10 parts.

[0047] The second embodiment of the present invention provides a method for preparing a high-damping, high-airtightness rubber composition, comprising: S100, uniformly mixing liquid butyl rubber and halogenated butyl rubber to obtain a masterbatch containing liquid butyl rubber; S200, mixing the masterbatch with a reinforcing agent, a vulcanization system and a processing aid and vulcanizing to obtain a target rubber composition; wherein the high-damping, high-airtightness rubber composition is the rubber composition as described above.

[0048] In S100, the mixing method is liquid phase mixing, in which liquid butyl rubber is dissolved in an organic solvent to form a first solution, which is then introduced into the halogenated butyl rubber solution for mixing, and the masterbatch is obtained after solvent removal treatment.

[0049] A third embodiment of the present invention provides an electric vehicle tire, the tire comprising an inner liner made of the rubber composition as described above.

[0050] The thickness of the inner lining layer is no greater than 0.9 mm.

[0051] 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.

[0052] Table 1: Formulations of each embodiment in performance testing

[0053] Component Name Example 1 Example 2 Comparative Example 1 Comparative Example 2 Component Function Description Halogenated butyl rubber (BIIR) 100 100 100 100 Matrix rubber Liquid butyl rubber (LBR) 20 20 - - Damping plasticizer Paraffin-based mineral oil - - 10 - Traditional plasticizers Polyisobutylene (PIB) - - - 20 Does not contain unsaturated structures Carbon Black N660 50 50 50 50 Reinforcing agent (median value) Zinc oxide 3 3 3 3 Vulcanizing agent (median value) sulfur 0.5 0.5 0.5 0.5 Vulcanizing agent (median value) stearic acid 2 2 2 2 Processing aids (median value) C5 resin 5 5 5 5 Processing aids (median value)

[0054] (I) Example 1:

[0055] Take 100 parts of brominated butyl rubber (BIIR), and introduce 20 parts of liquid butyl rubber in its solution post-treatment stage. The liquid butyl rubber is an isobutylene-isoprene copolymer with a weight-average molecular weight of about 25,000 g / mol and an isoprene structural unit content of about 2.0 mol.

[0056] The above mixed solution was subjected to desolventizing, coagulation, and drying treatment to obtain a halogenated butyl rubber masterbatch pre-filled with the liquid butyl rubber. Subsequently, carbon black, vulcanizing agent, and additives were added, and the mixture was compounded and vulcanized to obtain a vulcanized rubber composition.

[0057] Tests showed that the gas permeability coefficient of this vulcanized rubber composition at 60°C was 1.9 × 10⁻⁶. -16 mol·m / (m 2 The loss factor tanδ (·s·Pa) measured at 60℃ and 10Hz is 0.28; its 100% constant tensile stress is 1.0MPa; and its Shore A hardness is 51.

[0058] (II) Example 2:

[0059] Take 100 parts of brominated butyl rubber (BIIR), and introduce 20 parts of liquid butyl rubber into its solution post-treatment stage. The liquid butyl rubber is an isobutylene-isoprene copolymer with a weight-average molecular weight of about 42,000 g / mol and an isoprene structural unit content of about 1.0 mol.

[0060] The above mixed solution was subjected to desolventizing, coagulation, and drying treatment to obtain a halogenated butyl rubber masterbatch pre-filled with the liquid butyl rubber. Subsequently, carbon black, vulcanizing agent, and additives were added, and the mixture was compounded and vulcanized to obtain a vulcanized rubber composition.

[0061] Tests showed that the gas permeability coefficient of this vulcanized rubber composition at 60°C was 1.9 × 10⁻⁶. -16 mol·m / (m 2 The loss factor tanδ measured at 60℃ and 10Hz is 0.26; its 100% constant tensile stress is 0.9MPa; and its Shore A hardness is 49.

[0062] The results show that when the molecular weight of liquid butyl rubber is in the range of 25000 g / mol–45000 g / mol, the technical solution of the present invention can stably achieve a synergistic improvement in acoustic damping performance and airtightness performance.

[0063] (III) Comparative Example 1: Mineral Oil Plasticizing System

[0064] Take 100 parts of brominated butyl rubber, add 10 parts of paraffinic mineral oil, and mix and vulcanize according to the conventional tire inner liner formula. The resulting vulcanized rubber is used as a comparative sample.

[0065] Test results show that the gas permeability coefficient of this vulcanizate at 60°C is 2.4 × 10⁻⁶. -16 mol·m / (m 2 The strength of the sample was significantly higher than that of Examples 1–2 (·s·Pa); the loss factor tanδ was 0.20 under the conditions of 60℃ and 10Hz, which had a limited effect on suppressing the resonance noise of the tire cavity; its 100% constant tensile stress was 0.6MPa, and its Shore A hardness was 47, which was significantly lower than that of the sample in the examples, showing lower structural strength.

[0066] Furthermore, after the thermal aging test, it was observed that the mineral oil tended to migrate to the adjacent rubber layer, indicating that the system is at risk of performance degradation during long-term use.

[0067] (iv) Comparative Example 2: Non-vulcanizable polyisobutylene system

[0068] Take 100 parts of brominated butyl rubber and introduce 20 parts of polyisobutylene (PIB) with a weight-average molecular weight of approximately 35,000 g / mol, wherein the polyisobutylene does not contain unsaturated structural units. Prepare vulcanizate samples using the same mixing and vulcanization process as in the examples.

[0069] Test results show that the gas permeability coefficient of this vulcanizate at 60℃ is 2.2 × 10⁻⁶. -16 mol·m / (m 2 Its 100% tensile stress is 0.5 MPa, and its Shore A hardness is 46, which is significantly lower than that of the example sample, indicating lower structural strength.

[0070] Meanwhile, in dynamic mechanical testing, its loss factor tanδ under conditions of 60℃ and 10Hz was 0.22, which failed to meet the high damping level required by this invention.

[0071] (V) Application Examples

[0072] The rubber compositions obtained in Examples 1-2 were calendered into a rubber film with a thickness of 0.7 mm and applied as an inner liner in electric vehicle tires. Test results showed that, without the use of any external sound-absorbing materials, the interior cavity noise level of this tire was significantly lower than that of the comparison tire using a conventional mineral oil-plasticized inner liner.

[0073] Based on the performance test results, the beneficial effects of the rubber composition of the present invention are as follows: By introducing liquid butyl rubber with a specific molecular weight and unsaturated structural unit content, the gas permeability coefficients of Examples 1–2 are all as low as 1.9 × 10⁻⁶. -16mol·m / (m 2 (·s·Pa), significantly better than Comparative Example 1's 2.4×10 -16 mol·m / (m 2 ·s·Pa) and 2.2×10 of Comparative Example 2 -16 mol·m / (m 2 The results show that the liquid butyl rubber, with its polyisobutylene backbone structure identical to the matrix, effectively reduces the free volume of the material. The improved airtightness supports the thinning of the inner liner to 0.6-0.7 mm to achieve lightweighting. Simultaneously, the loss factor tanδ of the example at 60°C and 10Hz reaches 0.26-0.28, significantly exceeding the 0.20-0.22 of the comparative example. This demonstrates that the suspended chain structure formed by the co-vulcanizable liquid butyl rubber in the network significantly enhances energy dissipation and effectively suppresses cavity resonance noise in electric vehicle tires. Furthermore, the 100% tensile stress of the example is not less than 0.9 MPa, overcoming the performance degradation caused by mineral oil migration in Comparative Example 1 and the insufficient strength (only 0.5 MPa) of the non-vulcanizable system in Comparative Example 2. It achieves a system synergy of high damping, high airtightness, and high strength without external sound-absorbing materials, significantly improving the tire's quietness and service reliability.

[0074] 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 high-damping, high-airtightness rubber composition, characterized in that, Includes the following components in parts by weight: 100 parts of halogenated butyl rubber; 10-30 parts of liquid butyl rubber; 30-80 parts of reinforcing agent; Vulcanization system: 1.3–6 parts; Processing aids: 4-13 parts; The liquid butyl rubber is a copolymer of isobutylene and conjugated diene, with a weight-average molecular weight of 10,000 g / mol to 50,000 g / mol, and the content of structural units derived from conjugated diene in the liquid butyl rubber is 0.5 mol% to 4 mol%. The content of mineral oil plasticizer in each component is less than 2 parts.

2. The high-damping, high-airtightness rubber composition according to claim 1, characterized in that, The liquid butyl rubber has a weight-average molecular weight of 25,000 g / mol to 45,000 g / mol and a content of 15 to 25 parts.

3. The high-damping, high-airtightness rubber composition according to claim 1, characterized in that, The halogenated butyl rubber includes at least one of brominated butyl rubber and chlorinated butyl rubber.

4. The high-damping, high-airtightness rubber composition according to claim 1, characterized in that, The reinforcing agent used is carbon black N660.

5. The high-damping, high-airtightness rubber composition according to claim 1, characterized in that, The sulfidation system includes at least one of zinc oxide and sulfur; The zinc oxide content is 1 to 5 parts, and the sulfur content is 0.3 to 1 part.

6. The high-damping, high-airtightness rubber composition according to claim 1, characterized in that, The processing aid includes at least one of stearic acid and C5 resin; The content of stearic acid is 1 to 3 parts, and the content of C5 resin is 3 to 10 parts.

7. A method for preparing a high-damping, high-airtightness rubber composition, characterized in that, include: S100, liquid butyl rubber and halogenated butyl rubber are uniformly mixed to obtain a masterbatch containing liquid butyl rubber; S200, the masterbatch is mixed with reinforcing agent, vulcanization system and processing aid and vulcanized to obtain target rubber composition; The high-damping, high-airtightness rubber composition is the rubber composition as described in any one of claims 1-6.

8. The method for preparing the high-damping, high-airtightness rubber composition according to claim 7, characterized in that, The mixing method in S100 is liquid phase mixing, in which liquid butyl rubber is dissolved in an organic solvent to form a first solution, which is then introduced into the halogenated butyl rubber solution for mixing, and the masterbatch is obtained after solvent removal treatment.

9. An electric vehicle tire, characterized in that, The tire includes an inner liner made of any one of the rubber compositions of claims 1–6.

10. The electric vehicle tire according to claim 8, characterized in that, The thickness of the inner lining layer is no greater than 0.9 mm.