Sidewall rubber composition, method for producing the same, and pneumatic tire sidewall

Abstract

The application provides a tire side rubber composition, a preparation method thereof and a pneumatic tire tire side, relates to the technical field of rubber manufacturing methods, and comprises 100 parts of a rubber matrix, 35-40 parts of carbon black, 4-5 parts of an activator, 2.5-3 parts of a vulcanizing agent and 1-3 parts of a metal powder. The preparation method of the composition comprises the following steps: adding the rubber matrix into a mixer, pressurizing the rubber matrix to obtain pressurized rubber, lifting the pressurized rubber, adding the carbon black, the activator, the metal powder and the vulcanizing agent into the pressurized rubber in sequence and mixing to obtain a mixed rubber, and stirring the mixed rubber and discharging the mixed rubber to obtain the tire side rubber composition. The application solves the technical problems that the tire side rubber composition is damaged in structure when subjected to external force and the tire side is damaged due to fatigue, reduces the service life of the tire, enhances the strength of the tire side, improves the lateral stability, improves the flexing performance and the anti-deformation capability, improves the fatigue performance of the tire side and reduces the technical effect of the crack of the tire side.

Description

Technical Field

[0001] This invention relates to the field of rubber manufacturing technology, specifically to a sidewall rubber composition and its preparation method, and also to a sidewall using the sidewall rubber composition as a pneumatic tire. Background Technology

[0002] With the development of the automotive industry, people's expectations for tire performance are constantly rising. Not only are good wear resistance and anti-skid properties required, but stringent standards are also being imposed on the strength, stability, flexural strength, and fatigue resistance of pneumatic tire sidewalls. As a key component, the performance of the pneumatic tire sidewall directly affects the overall quality of the tire and vehicle driving safety; and the performance of the sidewall largely depends on the rubber composition used to prepare it.

[0003] The rubber compositions used in the prior art for preparing pneumatic tire sidewalls have limited basic properties due to the selection of raw materials, making it difficult to meet the strength and deformation resistance requirements of pneumatic tire sidewalls. When subjected to external forces, pneumatic tire sidewalls made from such rubber compositions are prone to structural damage, resulting in insufficient sidewall strength. When the vehicle is traveling at high speed or turning, the sidewall is easily deformed, which seriously affects the lateral stability of the tire and the vehicle's handling.

[0004] Furthermore, during the repeated flexing of the tire, under the action of complex mechanical stress, the sidewall of the pneumatic tire made of the existing sidewall rubber combination is very prone to fatigue damage, which in turn causes cracks and significantly shortens the service life of the tire. Summary of the Invention

[0005] The purpose of this invention is to provide a sidewall rubber composition to alleviate the technical problems of structural damage and fatigue damage at the sidewall when the sidewall rubber composition is subjected to external force, thereby reducing tire service life.

[0006] Another object of the present invention is to provide a method for preparing a sidewall rubber composition.

[0007] Another object of the present invention is to provide a sidewall rubber composition for use as the sidewall of a pneumatic tire.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] This invention provides a sidewall rubber composition;

[0010] It consists of the following components in parts by weight:

[0011] 100 parts rubber matrix; 35-40 parts carbon black; 4-5 parts activator; 2.5-3 parts vulcanizing agent; 1-3 parts metal powder.

[0012] Furthermore, the rubber matrix includes natural rubber and butadiene rubber; natural rubber accounts for 50-60 parts, and butadiene rubber accounts for 40-50 parts.

[0013] Furthermore, the activator includes zinc oxide and stearic acid; zinc oxide is 2.5 to 4 parts and stearic acid is 1 to 2 parts.

[0014] Furthermore, the vulcanizing agent includes an accelerator and sulfur; the accelerator is 0.8 to 2 parts, and the sulfur is 1 to 1.8 parts.

[0015] Furthermore, the accelerator includes at least one of sulfenamides, thiazoles, thiurams, thioureas, dithiocarbamates, aldehydes, guanidines, or xanthates.

[0016] Furthermore, the metal powder is iron powder with a particle size D50 of 0.1 μm to 0.5 μm.

[0017] The present invention also provides a method for preparing a tire sidewall rubber composition, comprising the following steps:

[0018] Step 1: Add 100 parts of rubber matrix to the internal mixer and pressurize it to obtain pressurized rubber;

[0019] Step 2: Raise the pressure block and add 35-40 parts of carbon black, 4-5 parts of activator, 1-3 parts of metal powder and 2.5-3 parts of vulcanizing agent to the pressurized rubber in sequence for mixing to obtain the compound rubber.

[0020] Step 3: After stirring the compounded rubber, discharge the rubber to obtain the sidewall rubber composition.

[0021] Furthermore, in step 1, the mixing is carried out at 120℃~165℃; in step 2, the mixing speed is 40r / min~60r / min, and the mixing time is 5min~10min.

[0022] Furthermore, in step 3, the stirring speed is 20 r / min to 35 r / min, and the stirring time is 30 s to 60 s.

[0023] The present invention also provides a pneumatic tire sidewall, which is prepared using a sidewall rubber composition.

[0024] Beneficial effects:

[0025] The present invention comprises the following components by weight: 100 parts rubber matrix; 35-40 parts carbon black; 4-5 parts activator; 2.5-3 parts vulcanizing agent; and 1-3 parts metal powder.

[0026] By adding carbon black and dispersing it evenly in the rubber matrix, a stable reinforcing network structure is formed, which greatly improves the strength of the tire sidewall, making it able to withstand greater external impacts without being easily damaged. The combined action of 4-5 parts activator and 2.5-3 parts vulcanizing agent optimizes the rubber vulcanization system, thereby improving the flexural properties and deformation resistance of the tire sidewall, giving the sidewall rubber better elastic recovery ability, and effectively resisting deformation during frequent flexing, reducing internal damage caused by deformation.

[0027] One to three parts of appropriate metal powder effectively enhance the rigidity of the tire sidewall, enabling the tire to maintain better lateral support during driving, especially when cornering, significantly improving lateral stability and reducing the risk of vehicle rollover.

[0028] The pneumatic tire sidewall prepared using this invention can achieve the effects of enhancing sidewall strength, improving lateral stability, improving flexural performance and resistance to deformation, improving sidewall fatigue performance, and reducing sidewall cracks.

[0029] The method for preparing the rubber composition for tire sidewalls of the present invention is simple to operate, can greatly improve production speed, and meet the output requirements of large-scale production. Attached Figure Description

[0030] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1 The flowchart illustrates the preparation method of the tire sidewall rubber composition provided in this embodiment of the invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0033] In a first aspect, the present invention provides a tire sidewall rubber composition, comprising the following components in parts by weight:

[0034] The rubber matrix consists of 100 parts; carbon black of 35-40 parts; activator of 4-5 parts; vulcanizing agent of 2.5-3 parts; and metal powder of 1-3 parts.

[0035] In embodiments of the present invention, the carbon black may be, but is not limited to, 35 parts, 38 parts or 40 parts by weight.

[0036] The activator can be, but is not limited to, 4 parts, 4.5 parts, or 5 parts by weight.

[0037] The amount of vulcanizing agent can be, but is not limited to, 2.5 parts, 2.8 parts, or 3 parts by weight.

[0038] The metal powder can be, but is not limited to, 1 part, 2 parts or 3 parts by weight.

[0039] It should be noted that 100 parts of rubber matrix provide the core elasticity and flexibility for the entire sidewall rubber composition. Sufficient rubber matrix ensures the tire can effectively cushion vibrations under various road conditions, improving ride comfort. At the same time, it facilitates the even distribution of all components.

[0040] It should be noted that carbon black, at a ratio of 35-40 parts, can fully bond with the rubber matrix, enhancing the strength of the tire sidewall. It is evenly dispersed within the rubber matrix, forming a reinforcing network that improves the sidewall's resistance to external wear and tear, thus extending tire life. The appropriate amount ensures the reinforcing effect without causing the rubber to become too hard due to excessive addition, which would negatively impact the overall tire performance.

[0041] It should be noted that 2.5 to 3 parts of vulcanizing agent and 4 to 5 parts of activator work synergistically. The activator can reduce the reaction activation energy, accelerate the vulcanization speed, shorten the production cycle, and improve production efficiency; while the vulcanizing agent can enable the rubber molecular chains to form an ideal cross-linking density, thereby improving the elasticity, strength, and aging resistance of the rubber.

[0042] It should be noted that the metal powder in the sidewall rubber has high strength and hardness. After 1 to 3 parts of metal powder are evenly dispersed in the rubber matrix, the sidewall’s ability to resist external forces such as tension and compression is greatly enhanced, making the sidewall less prone to cracking or deformation when subjected to greater pressure.

[0043] Metal powder in the rubber matrix can inhibit the relative displacement and deformation of rubber molecular chains during repeated flexing. When the tire sidewall is subjected to repeated bending, the metal powder can disperse stress and prevent stress concentration, thereby effectively reducing fatigue cracks caused by flexing, improving the tire sidewall's resistance to deformation, and ensuring that the tire maintains good performance under frequent flexing conditions.

[0044] Because the metal powder enhances the overall strength and toughness of the tire sidewall, it is less likely to crack when the sidewall is subjected to fatigue loads. Even if a small crack appears, it can effectively prevent it from expanding further, greatly extending the tire's service life and reducing safety hazards caused by sidewall problems.

[0045] In an embodiment of the present invention, the rubber matrix comprises 50 to 60 parts of natural rubber and 40 to 50 parts of butadiene rubber; for example, 60 parts of natural rubber and 40 parts of butadiene rubber.

[0046] In embodiments of the present invention, the activator comprises a mixture of 2.5 to 4 parts zinc oxide and 1 to 2 parts stearic acid; for example, 2.5 parts zinc oxide and 1.5 parts stearic acid.

[0047] In embodiments of the present invention, the vulcanizing agent comprises 0.8 to 2 parts of an accelerator and 1 to 1.8 parts of sulfur; for example, it may be 1 part of an accelerator and 2 parts of sulfur.

[0048] In embodiments of the present invention, the accelerator includes one or more of the following: sulfenamides, thiazoles, thiurams, thioureas, dithiocarbamates, aldehyde amines, guanidines, or xanthates. For example, it can be a guanidine, a xanthate, or a mixture of the above.

[0049] In embodiments of the present invention, the metal powder is iron powder, and the particle size D50 of the iron powder is 0.1 μm to 0.5 μm. Preferably, it is 0.5 μm. When the particle size D50 is in the range of 0.1 to 0.5 μm, the smaller particle size (e.g., 0.5 μm) is easily and uniformly dispersed in the matrix composed of natural rubber and butadiene rubber under the shear force of the internal mixer, effectively inhibiting excessive slippage of rubber molecular chains during flexure, thereby improving the fatigue life of the tire sidewall. Iron powder in this median particle size range can act as a stress dispersion node, uniformly transferring external loads to the rubber matrix, reducing crack initiation caused by stress concentration, and enhancing the rigidity of the tire sidewall, thereby improving lateral stability by 15% to 20%. Conversely, if the particle size is too large (40 to 50 μm), uneven dispersion will cause filler sedimentation during processing, leading to fluctuations in the performance of the tire sidewall rubber.

[0050] Secondly, such as Figure 1 As shown, the present invention provides a method for preparing a tire sidewall rubber composition, which includes the following steps:

[0051] Step 1: Add 100 parts of rubber matrix to a mixer and pressurize it to obtain pressurized rubber; in Step 1, the mixing temperature is 120℃~165℃.

[0052] Step 2: Raise the pressure block and add 35-40 parts of carbon black, 4-5 parts of activator, 1-3 parts of metal powder and 2.5-3 parts of vulcanizing agent to the pressurized rubber in sequence for mixing to obtain the compound rubber; the mixing speed in Step 2 is 40 r / min to 60 r / min and the mixing time is 5 min to 10 min.

[0053] Step 3: After mixing the rubber compound, discharge the rubber by stirring at a speed of 20 r / min to 35 r / min for 30 s to 60 s to obtain the sidewall rubber composition.

[0054] This invention involves first adding 100 parts of rubber matrix to a mixer and applying pressure. This pressure helps to initially compact the rubber matrix, expel internal air, and make its structure more compact. The mixing temperature is controlled between 120℃ and 165℃. This temperature range allows the rubber matrix to reach a suitable softening state, facilitating the subsequent mixing and dispersion of additives, while preventing premature aging or performance degradation of the rubber due to excessively high temperatures.

[0055] After the rubber is compressed, the components are added sequentially: first, carbon black is added, which can quickly disperse and begin to form a reinforcing network in the softened state of the rubber; then, an activator is added, which can gradually come into contact with the rubber and other components during the mixing process and play a catalytic role; metal powder is then added, which is evenly distributed in the rubber matrix under the stirring action of the mixing process, enhancing the various properties of the tire sidewall; finally, a vulcanizing agent is added, at which point the other components have been basically mixed evenly, and the vulcanizing agent can more effectively undergo a cross-linking reaction with the rubber molecules.

[0056] The rubber compound is discharged at a stirring speed of 20-35 rpm for 30-60 seconds. The lower stirring speed avoids excessive damage to the already homogeneous compound structure during discharge, ensuring product performance stability. The appropriate stirring time ensures smooth discharge of the compound and further fine-tunes the distribution of each component, resulting in a more uniform quality of the final sidewall rubber composition. This is beneficial for subsequent molding and vulcanization processes, improving product yield and overall performance.

[0057] Thirdly, the present invention also provides a method for using a sidewall rubber composition as the sidewall of a pneumatic tire.

[0058] The features and performance of the present invention will be further described in detail below with reference to specific embodiments.

[0059] Example 1

[0060] Example 1 provides a sidewall rubber composition, which is composed of the following components in parts by weight: 100 parts of rubber matrix (60 parts of natural rubber and 40 parts of butadiene rubber); 35 parts of carbon black; 4 parts of activator (2.5 parts of zinc oxide and 1.5 parts of stearic acid); 2.5 parts of vulcanizing agent (1 part of accelerator and 1.5 parts of sulfur); and 1 part of metal powder (iron powder with a particle size of 0.5 μm and a D50).

[0061] The preparation method of this embodiment 1 includes: adding a rubber matrix to a mixer and then pressing it to obtain pressurized rubber; mixing the rubber at 120°C; raising the mixer and sequentially adding carbon black, activator, metal powder and vulcanizing agent to the pressurized rubber to obtain a compound; the mixing speed is 40 r / min and the mixing time is 5 min; the compound is stirred and then discharged, the stirring speed is 20 r / min and the stirring time is 30 s.

[0062] Example 2

[0063] This embodiment 2 provides a sidewall rubber composition, which is a rubber for the sidewall and is composed of the following components in parts by weight: 100 parts of rubber matrix (50 parts of natural rubber and 50 parts of butadiene rubber); 38 parts of carbon black; 4.5 parts of activator (3.5 parts of zinc oxide and 1 part of stearic acid); 2.8 parts of vulcanizing agent (1 part of accelerator and 1.8 parts of sulfur); and 2 parts of metal powder (iron powder with a particle size of 0.5 μm and a D50).

[0064] The preparation method of this embodiment differs from that of Example 1 in that the mixing is carried out at 140°C with a mixing speed of 50 r / min and a stirring time of 7 min; after the mixed rubber is stirred, it is discharged with a stirring speed of 30 r / min and a stirring time of 50 s.

[0065] Example 3

[0066] This embodiment 3 provides a sidewall rubber composition, which is a rubber for the sidewall and is composed of the following components in parts by weight: 100 parts of rubber matrix (60 parts of natural rubber and 40 parts of butadiene rubber); 40 parts of carbon black; 5 parts of activator (4 parts of zinc oxide and 1 part of stearic acid); 3 parts of vulcanizing agent (1.3 parts of accelerator and 1.7 parts of sulfur); and 3 parts of metal powder (iron powder with a particle size of 0.5 μm and a D50).

[0067] The preparation method of this embodiment differs from that of Example 1 in that the mixing is carried out at 165°C, the mixing speed is 60 r / min, and the mixing time is 10 min; after stirring the mixed rubber, the rubber is discharged, the stirring speed is 35 r / min, and the stirring time is 60 s.

[0068] Comparative Example 1

[0069] Comparative Example 1 provides a rubber composition for tire sidewalls, which is prepared in the same way as in Example 3, except that no metal powder is added to the components.

[0070] The sidewall rubber compositions obtained in Examples 1-3 were compared with those in Comparative Example 1 in terms of thermal conductivity, volume resistivity, and fatigue life. The results are shown in Table 1.

[0071] Sidewall Comparative Example 1 Example 1 Example 2 Example 3 Iron powder (parts) 0 1 2 3 Iron powder particle size D50 (μm) 0 0.5 0.5 0.5 Thermal conductivity (W / m·℃) 0.2 0.22 0.24 0.26 Volume resistivity (Ω·cm) <![CDATA[4.31×10 6 ]]> <![CDATA[3.88×10 6 ]]> <![CDATA[3.49×10 6 ]]> <![CDATA[3.14×10 6 ]]> Sidewall fatigue life <![CDATA[4.94×10 7 ]]> <![CDATA[5.91×10 7 ]]> <![CDATA[5.69×10 7 ]]> <![CDATA[5.62×10 7 ]]>

[0072] Table 1

[0073] Thermal conductivity: The thermal conductivity of Comparative Example 1 was 0.2, while the thermal conductivity of Examples 1-3 were 0.22, 0.24, and 0.26, respectively. The thermal conductivity gradually increased with the addition of iron powder, indicating that the addition of iron powder helps improve the thermal conductivity of the tire sidewall rubber. Compared to Comparative Example 1 without added iron powder, Examples 1-3 performed better in terms of thermal conductivity, effectively reducing the risk of performance degradation due to heat accumulation during tire use and extending tire lifespan.

[0074] Volume resistivity: The volume resistivity of Examples 1 to 3 is lower than that of Comparative Example 1, indicating that the conductivity of the sidewall rubber is improved after the addition of iron powder.

[0075] Sidewall fatigue life: The sidewall fatigue life of Comparative Example 1 was 4.94 × 10⁻⁶, while the sidewall fatigue lives of Examples 1-3 were 5.91 × 10⁻⁶, 5.69 × 10⁻⁶, and 5.62 × 10⁻⁶, respectively. The sidewall fatigue lives of Examples 1-3 were significantly higher than those of Comparative Example 1, indicating that the addition of iron powder greatly improved the fatigue resistance of the sidewall rubber, enabling it to better withstand repeated deformation and stress during tire operation, reducing the possibility of sidewall cracks and fissures, and improving tire reliability and durability.

[0076] Examples 1-3 are superior to Comparative Example 1 in terms of thermal conductivity, volume resistivity, and fatigue life.

[0077] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tire sidewall rubber composition, characterized in that, It consists of the following components in parts by weight: 100 parts rubber matrix; 35-40 parts carbon black; 4-5 parts activator; 2.5-3 parts vulcanizing agent; 1-3 parts metal powder; The metal powder is iron powder, and the particle size D50 of the iron powder is 0.1μm to 0.5μm.

2. The sidewall rubber composition according to claim 1, characterized in that, The rubber matrix includes natural rubber and butadiene rubber; the natural rubber is 50-60 parts and the butadiene rubber is 40-50 parts.

3. The sidewall rubber composition according to claim 2, characterized in that, The activator includes zinc oxide and stearic acid; the zinc oxide is 2.5 to 4 parts and the stearic acid is 1 to 2 parts.

4. The sidewall rubber composition according to claim 3, characterized in that, The vulcanizing agent includes an accelerator and sulfur; the accelerator is 0.8 to 2 parts, and the sulfur is 1 to 1.8 parts.

5. The sidewall rubber composition according to claim 4, characterized in that, The accelerator includes at least one of sulfenamides, thiazoles, thiurams, thioureas, dithiocarbamates, aldehydes, guanidines, or xanthates.

6. A method for preparing a sidewall rubber composition, used to prepare the sidewall rubber composition according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Add 100 parts of the rubber matrix to a mixer and pressurize it to obtain pressurized rubber; Step 2: Raise the pressure block and add 35-40 parts of the carbon black, 4-5 parts of the activator, 1-3 parts of the metal powder and 2.5-3 parts of the vulcanizing agent to the pressurized rubber in sequence for mixing to obtain the compound rubber. Step 3: After stirring the compounded rubber, discharge the rubber to obtain the sidewall rubber composition.

7. The method for preparing the sidewall rubber composition according to claim 6, characterized in that, In step 1, the mixing is carried out at 120℃~165℃; in step 2, the mixing speed is 40r / min~60r / min, and the mixing time is 5min~10min.

8. The method for preparing the sidewall rubber composition according to claim 6, characterized in that, In step 3, the stirring speed is 20 r / min to 35 r / min, and the stirring time is 30 s to 60 s.

9. A sidewall of a pneumatic tire, characterized in that, It is prepared using the sidewall rubber composition according to any one of claims 1 to 5.

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