Tire sidewall rubber composition, preparation method thereof and pneumatic tire sidewall

Abstract

The invention provides a sidewall rubber composition, a preparation method of the sidewall rubber composition and a pneumatic tire sidewall, and relates to the technical field of rubber manufacturing methods. 35 to 40 parts of carbon black; 4-5 parts of an activating agent; 2.5-3 parts of a vulcanizing agent; 1-3 parts of metal powder; the preparation method of the composition comprises the following steps: adding a rubber matrix into an internal mixer, and pressurizing to obtain pressurized rubber; raising the pressure lump, sequentially adding carbon black, an activating agent, metal powder and a vulcanizing agent into the pressurized rubber, and mixing to obtain a rubber compound; and stirring the rubber compound, and discharging the rubber compound to obtain the sidewall rubber composition. The tire sidewall rubber composition solves the technical problems of structural damage and fatigue damage at the tire sidewall when the tire sidewall rubber composition is subjected to external force, and the service life of the tire is shortened, and achieves the technical effects of enhancing the tire sidewall strength, improving the lateral stability, improving the flexing performance and the deformation resistance, improving the tire sidewall fatigue performance and reducing the tire sidewall cracks.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber manufacturing methods, and particularly relates to a sidewall rubber composition and a preparation method thereof, and also relates to using the sidewall rubber composition as a sidewall of a pneumatic tire. Background Art

[0002] With the development of the vehicle industry, people's expectations for tire performance are constantly rising. Not only are tires required to have good wear resistance and anti-slip performance, but also strict standards are put forward for the strength, stability, flexure and fatigue resistance of the sidewalls of pneumatic tires. As a key part, the performance of the sidewall of a pneumatic tire is directly related to the overall quality of the tire and the driving safety of the vehicle; and the performance of the sidewall depends to a large extent on the rubber composition used to prepare it.

[0003] In the prior art, the rubber composition used to prepare the sidewall of a pneumatic tire has limited basic performance due to the selection of raw materials, and it is difficult to meet the requirements of the sidewall of a pneumatic tire for strength and anti-deformation ability. When subjected to external forces, the sidewall of a pneumatic tire made of such a rubber composition is prone to structural damage, resulting in insufficient sidewall strength. When the vehicle is driving at high speed or turning, the sidewall is prone to deformation, seriously affecting the lateral stability of the tire and the vehicle controllability.

[0004] In addition, during the repeated flexure of the tire, under the action of complex mechanical stresses, the sidewall of a pneumatic tire prepared from the sidewall rubber combination of the prior art is extremely prone to fatigue damage, and then cracks are generated, greatly shortening the service life of the tire. Summary of the Invention

[0005] The purpose of the present invention is to provide a sidewall rubber composition to alleviate the technical problems of structural damage of the sidewall rubber composition and fatigue damage at the sidewall when subjected to external forces in the prior art, and to reduce the service life of the tire.

[0006] Another purpose of the present invention is to provide a preparation method of the sidewall rubber composition.

[0007] Still another purpose of the present invention is to provide using the sidewall rubber composition as a sidewall of a pneumatic tire.

[0008] To achieve the above purposes, the technical solutions of the present invention are as follows:

[0009] The present invention provides a sidewall rubber composition;

[0010] By weight, it consists of the following components:

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

[0012] Furthermore, the rubber matrix includes natural rubber and cis-butadiene rubber; the natural rubber is 50 to 60 parts, and the cis-butadiene rubber is 40 to 50 parts.

[0013] Furthermore, 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.

[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, aldehyde amines, guanidines or xanthates.

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

[0017] The present invention also provides a preparation method of a sidewall rubber composition, including the following steps:

[0018] Step 1: Add 100 parts of the rubber matrix into a mixer and apply pressure to obtain the rubber after pressure application.

[0019] Step 2: Raise the pressure plug, and sequentially add 35 to 40 parts of carbon black, 4 to 5 parts of the activator, 1 to 3 parts of the metal powder and 2.5 to 3 parts of the vulcanizing agent to the rubber after pressure application for mixing to obtain a mixed rubber.

[0020] Step 3: Stir the mixed rubber and then discharge the rubber to obtain the sidewall rubber composition.

[0021] Furthermore, in Step 1, the pressure plug is mixed to 120°C to 165°C; in Step 2, the mixing rotation speed is 40 r / min to 60 r / min, and the mixing time is 5 min to 10 min.

[0022] Furthermore, in Step 3, the stirring rotation 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 an inflatable tire sidewall, and the inflatable tire sidewall is prepared by using the sidewall rubber composition.

[0024] Beneficial effects:

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

[0026] By adding carbon black and uniformly dispersing it in the rubber matrix, a stable reinforcing network structure is formed, greatly enhancing the strength of the tire sidewall, enabling it to withstand greater external force impacts without being easily damaged. The combined action of 4 - 5 parts of activator and 2.5 - 3 parts of vulcanizing agent optimizes the vulcanization system of the rubber, thereby improving the flexing performance and anti-deformation ability of the tire sidewall, endowing the sidewall rubber with better elastic recovery ability. During frequent flexing processes, it can effectively resist deformation and reduce internal damage caused by deformation.

[0027] And 1 - 3 parts of an appropriate amount of metal powder effectively enhance the rigidity of the tire sidewall, enabling the tire to maintain better lateral support during driving, especially during turning, significantly improving lateral stability and reducing the risk of vehicle rollover.

[0028] Using the tire sidewall prepared by the present invention can achieve the effects of enhancing the strength of the tire sidewall, improving lateral stability, enhancing flexing performance and anti-deformation ability, improving the fatigue performance of the tire sidewall, and reducing sidewall cracks.

[0029] The preparation method of the rubber composition of the tire sidewall of the present invention is simple to operate, can greatly improve the production speed, and meet the requirements of large-scale production for output. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is a flowchart of the preparation method of the tire sidewall rubber composition provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[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. Those not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0033] In a first aspect, the present invention provides a tire sidewall rubber composition, which is composed of the following components by weight:

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

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

[0036] In terms of weight parts, the activator can be, but is not limited to, 4 parts, 4.5 parts or 5 parts.

[0037] In terms of weight parts, the vulcanizing agent can be, but is not limited to, 2.5 parts, 2.8 parts or 3 parts.

[0038] In terms of weight parts, the metal powder can be, but is not limited to, 1 part, 2 parts or 3 parts.

[0039] It should be noted that 100 parts of the rubber matrix provides the core elasticity and flexibility for the entire sidewall rubber composition. A sufficient amount of rubber matrix ensures that the tire can effectively buffer vibrations under various road conditions and improve driving comfort. At the same time, it is conducive to the uniform distribution of various components.

[0040] It should be noted that carbon black can fully combine with the rubber matrix at a ratio of 35 to 40 parts to enhance the strength of the sidewall. It is evenly dispersed in the rubber matrix to form a reinforcement network, improve the sidewall's ability to resist external wear and tear, and extend the tire's service life. The appropriate number of parts ensures the reinforcement effect, but does not make the rubber too hard due to excessive addition, affecting the overall performance of the tire.

[0041] It should be noted that 2.5 to 3 parts of vulcanizer 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 vulcanizer can form an ideal cross-linking density between rubber molecular chains, thereby improving the elasticity, strength and aging resistance of the rubber.

[0042] It should be noted that in the sidewall rubber, the metal powder itself 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 likely to rupture or deform even when under greater pressure.

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

[0044] Because metal powder enhances the overall strength and toughness of the sidewall, it is more difficult for the sidewall to crack when subjected to fatigue loads. Even if tiny cracks occur, they can be effectively prevented from further expansion, greatly extending the service life of the tire and reducing safety hazards caused by sidewall problems.

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

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

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

[0048] In an embodiment of the present invention, the accelerator comprises one or more of sulfenamides, thiazoles, thiurams, thioureas, dithiocarbamates, aldehyde amines, guanidines or xanthates. For example, it can be guanidine, or it can be xanthate, or a mixture of the above-mentioned varieties.

[0049] In an embodiment 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 (such as 0.5 μm) is easily and uniformly dispersed in the matrix composed of natural rubber and cis-butadiene rubber under the shear force of the internal mixer, effectively inhibiting the excessive slip of rubber molecular chains during the flexing process, and improving the fatigue life of the tire sidewall. The iron powder with this median particle size range can serve as stress dispersion nodes, uniformly transfer the external load to the rubber matrix, reduce the crack initiation caused by stress concentration, and at the same time enhance the rigidity of the tire sidewall, increasing the lateral stability by 15% to 20%. On the contrary, if the particle size is too large (40 to 50 μm), it will cause the filler to settle during the processing due to uneven dispersion, resulting in fluctuations in the properties of the tire sidewall rubber.

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

[0051] Step 1: Add 100 parts of the rubber matrix into an internal mixer and apply pressure to obtain the pressurized rubber; in Step 1, the ram is kneaded to 120 °C to 165 °C;

[0052] Step 2: Raise the ram, and sequentially add 35 to 40 parts of carbon black, 4 to 5 parts of the activator, 1 to 3 parts of the metal powder and 2.5 to 3 parts of the vulcanizing agent to the pressurized rubber for kneading to obtain the kneaded rubber; the kneading speed in Step 2 is 40 r / min to 60 r / min, and the kneading time is 5 min to 10 min;

[0053] Step 3: Stir the mixed rubber and then discharge the rubber. The stirring speed is 20 r / min to 35 r / min, and the stirring time is 30 s to 60 s to obtain the sidewall rubber composition.

[0054] In the present invention, 100 parts of rubber matrix are first added to the internal mixer and pressurized. The pressurization operation helps to initially compact the rubber matrix, expel the internal air, and make its structure more compact. And the kneading temperature of the pressure pad is controlled at 120°C to 165°C. This temperature range can not only make the rubber matrix reach an appropriate softening state, which is conducive to the mixing and dispersion of subsequent additives, but also will not cause premature aging or performance deterioration of the rubber due to excessive temperature.

[0055] After raising the pressure pad, the components are added in sequence. First, carbon black is added, which can quickly disperse and start to form a reinforcing network in the softened state of the rubber; then the activator is added, which can gradually contact with the rubber and other components during the kneading process and play a catalytic role; the metal powder is added subsequently and is evenly distributed in the rubber matrix under the stirring action of the kneading, enhancing the various properties of the sidewall; finally, the vulcanizing agent is added. At this time, the other components are basically mixed evenly, and the vulcanizing agent can more effectively crosslink with the rubber molecules.

[0056] The mixed rubber is discharged at a stirring speed of 20 r / min to 35 r / min and a stirring time of 30 s to 60 s. The lower stirring speed can avoid excessive damage to the structure of the well-mixed mixed rubber during the discharging process, ensuring the stability of the product performance. And the appropriate stirring time ensures that the mixed rubber can be discharged smoothly, while further fine-tuning the distribution of each component, making the finally obtained sidewall rubber composition more uniform in quality, which is beneficial to subsequent processing procedures such as molding and vulcanization, and improving the qualified rate and overall performance of the product.

[0057] In the third aspect, the present invention also provides a use of the sidewall rubber composition as the sidewall of a pneumatic tire.

[0058] The features and performance of the present invention are further described in detail below in conjunction with specific embodiments.

[0059] Example 1

[0060] This Example 1 provides a sidewall rubber composition, as the rubber at the sidewall, which is composed of the following components by weight: 100 parts of rubber matrix (60 parts of natural rubber and 40 parts of cis-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); 1 part of metal powder (iron powder with a particle size D50 of 0.5 μm).

[0061] The preparation method of Example 1 includes: adding a rubber matrix into an internal mixer and applying pressure to obtain pressurized rubber; pressing and kneading to 120 °C; raising the pressing weight, and successively adding carbon black, activator, metal powder and vulcanizing agent to the pressurized rubber for kneading to obtain kneaded rubber; the kneading speed is 40 r / min and the kneading time is 5 min; stirring the kneaded rubber and then discharging the rubber, the stirring speed is 20 r / min and the stirring time is 30 s.

[0062] Example 2

[0063] Example 2 provides a sidewall rubber composition. As the rubber at the sidewall, it is composed of the following components by weight: 100 parts of rubber matrix (50 parts of natural rubber and 50 parts of cis-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); 2 parts of metal powder (iron powder with a D50 particle size of 0.5 μm).

[0064] The preparation method of this example is different from that of Example 1 in that the pressing and kneading is carried out to 140 °C, the kneading speed is 50 r / min, and the stirring time is 7 min; after stirring the kneaded rubber, discharging the rubber, the stirring speed is 30 r / min and the stirring time is 50 s.

[0065] Example 3

[0066] Example 3 provides a sidewall rubber composition. As the rubber at the sidewall, it is composed of the following components by weight: 100 parts of rubber matrix (60 parts of natural rubber and 40 parts of cis-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); 3 parts of metal powder (iron powder with a D50 particle size of 0.5 μm).

[0067] The preparation method of this example is different from that of Example 1 in that the pressing and kneading is carried out to 165 °C, the kneading speed is 60 r / min, and the kneading time is 10 min; after stirring the kneaded rubber, discharging the rubber, 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 sidewalls. Its preparation method is the same as that of Example 3, and the difference is that metal powder is not added to the components.

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

[0071] Sidewall rubber 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·°C) 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 is 0.2, and the thermal conductivities of Examples 1 to 3 are 0.22, 0.24, and 0.26 respectively. With the addition of iron powder, the thermal conductivity gradually increases, indicating that the addition of iron powder helps to improve the thermal performance of the sidewall rubber. Compared with Comparative Example 1 without the addition of iron powder, Examples 1 to 3 perform better in terms of heat conduction, can effectively reduce the risk of performance degradation caused by heat accumulation during tire use, and extend the service life of the tire.

[0074] Volume resistivity: The volume resistivities of Examples 1 to 3 are all lower than that of Comparative Example 1, indicating that the electrical conductivity of the sidewall rubber has been improved after adding iron powder.

[0075] Fatigue life of the sidewall: The fatigue life of the sidewall of Comparative Example 1 is 4.94×10, and the fatigue lives of the sidewalls of Examples 1 to 3 are 5.91×10, 5.69×10, and 5.62×10 respectively. The fatigue lives of the sidewalls of Examples 1 to 3 are significantly higher than that of Comparative Example 1, indicating that the addition of iron powder has greatly improved the fatigue resistance of the sidewall rubber, can better withstand the repeated deformation and stress during tire driving, reduce the possibility of problems such as cracks and splits on the sidewall, and improve the reliability and durability of the tire.

[0076] Examples 1 to 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 above specific embodiments have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A sidewall rubber composition, characterized in that it is composed of the following components by weight parts: 100 parts of rubber matrix; 35 - 40 parts of carbon black; 4 - 5 parts of activator; 2.5 - 3 parts of vulcanizing agent; 1 - 3 parts of metal powder.

2. The sidewall rubber composition according to claim 1, characterized in that the rubber matrix includes natural rubber and cis - butadiene rubber; the natural rubber is 50 - 60 parts, and the cis - 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 - 4 parts, and the stearic acid is 1 - 2 parts.

4. The sidewall rubber composition according to claim 3, characterized in that the vulcanizing agent includes accelerator and sulfur; the accelerator is 0.8 - 2 parts, and the sulfur is 1 - 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, aldehyde - amines, guanidines or xanthates.

6. The sidewall rubber composition according to claim 5, characterized in that the metal powder is iron powder, and the D50 particle size of the iron powder is 0.1μm - 0.5μm.

7. A preparation method of a sidewall rubber composition for preparing the sidewall rubber composition according to any one of claims 1 - 6, characterized in that it includes the following steps: Step 1: Add 100 parts of the rubber matrix into a mixer and apply pressure to obtain pressurized rubber; Step 2: Raise the ram, and sequentially 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 for mixing to obtain a mixed rubber; Step 3: Stir the mixed rubber and then discharge the rubber to obtain the sidewall rubber composition.

8. The preparation method of the sidewall rubber composition according to claim 7, characterized in that in Step 1, the ram is mixed to 120℃ - 165℃; the mixing speed in Step 2 is 40r / min - 60r / min, and the mixing time is 5min - 10min.

9. The preparation method of the sidewall rubber composition according to claim 7, characterized in that the stirring speed in Step 3 is 20r / min - 35r / min, and the stirring time is 30s - 60s.

10. An inflatable tire sidewall, characterized in that it is prepared by using the sidewall rubber composition according to any one of claims 1 - 6.

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