Self-repairing lunar vehicle tire tread rubber composition, preparation method thereof and tire

Abstract

The invention relates to the technical field of tire rubber manufacturing, and discloses a self-repairing lunar vehicle tire tread rubber composition, a preparation method thereof and a tire. The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 25-75 parts by weight of silicone rubber, 10-45 parts by weight of fluororubber, 15-30 parts by weight of ethylene propylene diene monomer, 30-50 parts by weight of carbon black, 2-8 parts by weight of an active agent, 2-4 parts by weight of an anti-aging agent and 5-15 parts by weight of polyurethane microcapsules. According to the invention, the silicone rubber, the fluororubber and the ethylene propylene diene monomer are adopted, and through scientific proportioning, the silicone rubber, the fluororubber and the ethylene propylene diene monomer generate a synergistic effect, so that the physical tensile properties of the rubber composition at low temperature (-100 DEG C) and high temperature (140 DEG C) are obviously improved; by adding a proper amount of polyurethane microcapsules, the tread rubber composition has self-repairing capability, so that the reliability and the running efficiency of the lunar rover are comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tire rubber manufacturing, and in particular to a self-repairing lunar rover tire tread rubber composition, a preparation method thereof, and a tire. Background Art

[0002] The National Aeronautics and Space Administration (NASA) developed ground vehicles to support long-distance lunar exploration and the development of a lunar base. These vehicles were heavier and required to travel greater distances than the Lunar Roving Vehicle (LRV) developed by the Apollo program in the late 1960s. Therefore, new tires were required to support up to ten times the weight and a hundred times the distance compared to the tires used on the Apollo LRV, requiring handling characteristics similar to those of Earth-based cars. However, conventional rubber pneumatic tires do not perform satisfactorily in space. Rubber properties vary significantly between the low temperatures of shadow (as low as -100°C) and the high temperatures of sunlight (as high as 140°C), and rubber degrades when exposed to direct solar radiation without atmospheric protection.

[0003] A Chinese invention patent (publication number: CN117511227A, publication date: February 6, 2024) discloses a weather-resistant, high- and low-temperature-resistant silicone rubber composition for tires. The composition comprises the following components, based on 100 parts by weight of rubber: 25-65 parts by weight of silicone rubber, 35-75 parts by weight of modified low-cis polybutadiene rubber, 30-50 parts by weight of carbon black, 2-6 parts by weight of an activator, 2-4 parts by weight of an antioxidant, and appropriate amounts of an accelerator and a vulcanizing agent. The silicone rubber is methyl vinyl silicone rubber 110-5. This silicone rubber composition exhibits both weather resistance and high- and low-temperature resistance, making it suitable for use in lunar rover tires. It ensures that the tire tread does not significantly deform under both low temperatures (as low as -100°C) and high temperatures (as high as 140°C).

[0004] As lunar exploration missions become increasingly complex, lunar rover tires will need to operate for extended periods in extreme environments. While existing lunar rover tire tread rubber compositions offer excellent resistance to high and low temperatures and weathering, they lack the ability to self-repair from damage such as micrometeorite impacts and lunar dust erosion on the lunar surface. Tiny cracks or punctures on the tire surface can lead to performance degradation or even failure, impacting the rover's normal operation. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a self-repairing lunar rover tire tread rubber composition, a preparation method thereof, and a tire.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A lunar rover tire tread rubber composition with a self-repairing function is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 25-75 parts by weight of silicone rubber, 10-45 parts by weight of fluororubber, 15-30 parts by weight of EPDM rubber, 30-50 parts by weight of carbon black, 2-8 parts by weight of active agent, 2-4 parts by weight of antioxidant, 5-15 parts by weight of polyurethane microcapsules; The capsule core of the polyurethane microcapsule is polyurethane, and the microcapsule shell is gelatin or polylactic acid.

[0007] Preferably, the rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 30-70 parts by weight of silicone rubber, 10-40 parts by weight of fluororubber, 20-25 parts by weight of EPDM rubber, 30-50 parts by weight of carbon black, 2-8 parts by weight of active agent, 2-4 parts by weight of antioxidant, 8-12 parts by weight of polyurethane microcapsules 0.5-3 parts by weight of accelerator, 2-6 parts by weight of vulcanizing agent.

[0008] Preferably, the fluororubber is a ternary copolymer of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene, wherein the content of vinylidene fluoride is 65-70%, and the contents of tetrafluoroethylene and hexafluoropropylene are both 15-17%.

[0009] Preferably, the EPDM rubber is a terpolymer of ethylene, propylene and a third monomer, wherein the content of ethylene and propylene are both 40-60%, and the content of the third monomer is 7-17%.

[0010] Preferably, the carbon black is one or more of N330, N375, N550, and N660; preferably, the carbon black is N375.

[0011] Preferably, the active agent is one or more of zinc oxide, stearic acid, and trimethylolpropane tris(3-mercaptopropionate), wherein zinc oxide is 2-5 parts by weight, stearic acid is 2-4 parts by weight, and trimethylolpropane tris(3-mercaptopropionate) is 1-3 parts by weight.

[0012] Preferably, the antioxidant is antioxidant TMQ and / or antioxidant 6PPD, wherein the antioxidant TMQ is 1-3 parts by weight and the antioxidant 6PPD is 1-3 parts by weight.

[0013] Preferably, the accelerator is accelerator CZ and / or accelerator TBzTD, wherein the accelerator CZ is 1-2 parts by weight and the accelerator TBzTD is 0.5-1.5 parts by weight.

[0014] Furthermore, the present invention also provides a method for preparing the tread rubber composition, comprising the following steps: 1) Mixing: Use a tangential internal mixer, set the mixer rotor speed to 40-55 rpm, the upper bolt pressure to 4.2±0.2 bar, and the mixer cooling water temperature to 25-40°C; a. Add all silicone rubber, fluororubber and EPDM rubber, press the top bolt and hold for 10-20 seconds; b. Raise the top plug, add carbon black, active agent, antioxidant and polyurethane microcapsules, and press the top plug to heat the rubber to 100-110℃; c. Raise the top bolt and hold for 6-10 seconds; d. Press the top bolt to heat the rubber compound to 120-130℃, raise the top bolt, discharge the rubber compound and press it into sheets to obtain the masterbatch; 2) Final refining and sulfur addition: Use a tangential internal mixer, set the internal mixer rotor speed to 15-30rpm, the upper bolt pressure to 4.2±0.2bar, and the internal mixer cooling water temperature to 25-40℃; a. Add the mixed masterbatch, vulcanizing agent and accelerator, and press the top bolt to heat the rubber to 70-80℃; b. Raise the top bolt and hold it for 6-10 seconds; c. Press the top bolt to raise the temperature of the rubber compound to 80-90℃; d. Raise the top bolt and hold for 6-8 seconds; e. Press the top bolt to raise the temperature of the rubber compound to 90-95℃, and then discharge the rubber compound and press it into sheets.

[0015] Furthermore, the present invention also provides a lunar rover tire, wherein the non-tread portion of the tire is made of metal, and the tread is prepared by vulcanizing the tread rubber composition.

[0016] The beneficial effects of the present invention are as follows: the present invention adopts silicone rubber, fluororubber and EPDM rubber. Through scientific proportioning, silicone rubber, fluororubber and EPDM rubber produce a synergistic effect, which significantly improves the physical tensile properties of the rubber composition at low temperature (-100°C) and high temperature (140°C); and by adding an appropriate amount of polyurethane microcapsules, the tread rubber composition has self-repairing ability, thereby comprehensively improving the reliability and operating efficiency of the lunar rover. DETAILED DESCRIPTION

[0017] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of protection of the present invention.

[0018] The formulations of the embodiments and comparative examples are shown in Table 1. Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Silicone rubber*1 100 / / 80 60 40 40 50 50 50 60 70 Fluororubber*2 / 100 / / 40 40 40 30 30 30 20 10 EPDM*3 / / 100 20 / 20 20 20 20 20 20 20 N375 40 40 40 40 40 40 40 40 40 40 40 40 zinc oxide 3 3 3 3 3 3 3 3 3 3 3 3 stearic acid 2 2 2 2 2 2 2 2 2 2 2 2 Trimethylolpropane tris(3-mercaptopropionate)*4 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 2.5 Antioxidant TMQ 2 2 2 2 2 2 2 2 2 2 2 2 Antioxidant 6PPD 2 2 2 2 2 2 2 2 2 2 2 2 Polyurethane microcapsules*5 / / / / / / 10 5 10 15 10 10 Accelerator CZ 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Accelerator TBzTD 1 1 1 1 1 1 1 1 1 1 1 1 sulfur 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2

[0019] Source of raw materials: 1. Silicone rubber 107, a product of Shenzhen Jingyi Chemical Co., Ltd. 2. Fluororubber 246, product of LG, South Korea; 3. EPDM rubber KEP350, a product of Kumho, South Korea. 4. Trimethylolpropane tris(3-mercaptopropionate), a product of Shanghai Yuanye Biotechnology Co., Ltd. 5. Polyurethane microcapsules, TPU32807, product of Huntsman International LLC; The remaining products are commercially available.

[0020] The mixing method of the embodiment is as follows: 1) Mixing: Use a tangential internal mixer with the rotor speed set to 50 rpm, the top bolt pressure to 4.2 bar, and the cooling water temperature to 30°C. a. Add all silicone rubber, fluororubber and EPDM rubber, press the top bolt and hold for 15 seconds; b. Raise the top bolt, add carbon black, activator and antioxidant, and press the top bolt to heat the rubber to 105℃; c. Raise the top bolt and hold for 8 seconds; d. Press the top bolt to heat the rubber compound to 125℃, raise the top bolt, discharge the rubber compound and press it into sheets to obtain the masterbatch; 2) Final refining and sulfur addition: Use a tangential internal mixer, set the internal mixer rotor speed to 25 rpm, the upper bolt pressure to 4.2 bar, and the internal mixer cooling water temperature to 30°C; a. Add the mixed masterbatch, vulcanizing agent and accelerator, and press the top bolt to heat the rubber to 75℃; b. Raise the top bolt and hold it for 8 seconds; c. Press the top bolt to raise the temperature of the rubber compound to 85°C; d. Raise the top bolt and hold for 7 seconds; e. Press the top bolt to raise the temperature of the rubber compound to 95℃, and then discharge the rubber compound and press it into sheets.

[0021] The mixing method of comparative examples and reference examples refers to that of the examples.

[0022] The tread rubber compositions obtained from the reference example, comparative example, and example were subjected to aging tests. The results are shown in Table 2. The data of the examples and comparative examples were processed with the performance of the reference example as 100%.

[0023] Aging tests are carried out at different temperatures, and the tensile strength and elongation at break are tested using a tensile testing machine. The larger the value, the greater the tensile strength and the elongation at break.

[0024] Low-temperature tensile test: vulcanization condition: 160°C x 15 min, aging condition: -100°C x 7 days, with Comparative Example 1 as 100% reference.

[0025] High temperature tensile test: vulcanization condition 160℃×15min, aging condition: first -100℃*7 days, then 140℃*7 days, with Comparative Example 1 as 100% reference.

[0026] Repair efficiency test: pre-cut, test the original tear strength after aging (T0), then measure the tear strength after repair (T1), calculate the repair efficiency (T1 / T0×100%), and take Example 3 as 100% as a reference.

[0027] Table 2 The above test results show that Example 3 is the best embodiment with the best comprehensive performance. By comparing 1-6, it can be seen that the scientific proportion of silicone rubber, fluororubber and EPDM rubber, as well as the synergistic effect of silicone rubber, fluororubber and EPDM rubber, can significantly improve the physical tensile properties of the rubber composition under low and high temperature conditions. And it can be seen from Examples 1, 3, 5, and 6 that the optimal ratio of silicone rubber, fluororubber and EPDM rubber is 50 parts of silicone rubber, 30 parts of fluororubber and 20 parts of EPDM rubber. It can be seen from Comparative Example 6 and Example 1 that when 10 parts of polyurethane microcapsules are added, it does not affect the high and low temperature resistance and weather resistance of the tire, and enables the tire to automatically repair and fill cracks when it suffers minor damage. At the same time, it can be seen from Examples 2-4 that when the addition amount of polyurethane microcapsules is 15 parts, it will affect the physical tensile properties of the rubber composition under low and high temperature conditions. Taking into account the physical tensile properties and automatic repair ability of the rubber composition, the addition amount of polyurethane microcapsules is best when it is 10 parts.

[0028] The above is a description of the embodiments of the present invention. The above description of the disclosed embodiments will enable professionals in the field to implement or use the present invention. Various modifications to these embodiments will be apparent to professionals in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A self-repairing lunar rover tire tread rubber composition, characterized in that: The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 25-75 parts by weight of silicone rubber, 10-45 parts by weight of fluororubber, 15-30 parts by weight of EPDM rubber, 30-50 parts by weight of carbon black, 2-8 parts by weight of active agent, 2-4 parts by weight of antioxidant, 5-15 parts by weight of polyurethane microcapsules; The capsule core of the polyurethane microcapsule is polyurethane, and the microcapsule shell is gelatin or polylactic acid.

2. The self-repairing lunar rover tire tread rubber composition according to claim 1, characterized in that: The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 30-70 parts by weight of silicone rubber, 10-40 parts by weight of fluororubber, 20-25 parts by weight of EPDM rubber, 30-50 parts by weight of carbon black, 2-8 parts by weight of active agent, 2-4 parts by weight of antioxidant, 8-12 parts by weight of polyurethane microcapsules 0.5-3 parts by weight of accelerator, 2-6 parts by weight of vulcanizing agent.

3. A self-repairing lunar rover tire tread rubber composition according to claim 1 or 2, characterized in that: The fluororubber is a ternary copolymer of vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene, wherein the content of vinylidene fluoride is 65-70%, and the contents of tetrafluoroethylene and hexafluoropropylene are both 15-17%.

4. A self-repairing lunar rover tire tread rubber composition according to claim 1 or 2, characterized in that: The EPDM rubber is a terpolymer of ethylene, propylene and a third monomer, wherein the content of ethylene and propylene is 40-60% each, and the content of the third monomer is 7-17%.

5. The self-repairing lunar rover tire tread rubber composition according to claim 1 or 2, characterized in that: The carbon black is one or more of N330, N375, N550, and N660; preferably, the carbon black is N375.

6. The self-repairing lunar rover tire tread rubber composition according to claim 1 or 2, characterized in that: The active agent is one or more of zinc oxide, stearic acid, and trimethylolpropane tris(3-mercaptopropionate), wherein the zinc oxide is 2-5 parts by weight, the stearic acid is 2-4 parts by weight, and the trimethylolpropane tris(3-mercaptopropionate) is 1-3 parts by weight.

7. The self-repairing lunar rover tire tread rubber composition according to claim 1 or 2, characterized in that: The antioxidant is antioxidant TMQ and / or antioxidant 6PPD, wherein the antioxidant TMQ is 1-3 parts by weight and the antioxidant 6PPD is 1-3 parts by weight.

8. The self-repairing lunar rover tire tread rubber composition according to claim 1 or 2, characterized in that: The accelerator is accelerator CZ and / or accelerator TBzTD, wherein the accelerator CZ is 1-2 parts by weight and the accelerator TBzTD is 0.5-1.5 parts by weight.

9. The method for preparing the tread rubber composition according to any one of claims 1 to 8, characterized in that: The following steps are involved: 1) Mixing: Use a tangential internal mixer, set the mixer rotor speed to 40-55 rpm, the upper bolt pressure to 4.2±0.2 bar, and the mixer cooling water temperature to 25-40°C; a. Add all silicone rubber, fluororubber and EPDM rubber, press the top bolt and hold for 10-20 seconds; b. Raise the top plug, add carbon black, active agent, antioxidant and polyurethane microcapsules, and press the top plug to heat the rubber to 100-110℃; c. Raise the top bolt and hold for 6-10 seconds; d. Press the top bolt to heat the rubber compound to 120-130℃, raise the top bolt, discharge the rubber compound and press it into sheets to obtain the masterbatch; 2) Final refining and sulfur addition: Use a tangential internal mixer, set the internal mixer rotor speed to 15-30rpm, the upper bolt pressure to 4.2±0.2bar, and the internal mixer cooling water temperature to 25-40℃; a. Add the mixed masterbatch, vulcanizing agent and accelerator, and press the top bolt to heat the rubber to 70-80℃; b. Raise the top bolt and hold it for 6-10 seconds; c. Press the top bolt to raise the temperature of the rubber compound to 80-90℃; d. Raise the top bolt and hold for 6-8 seconds; e. Press the top bolt to raise the temperature of the rubber compound to 90-95℃, and then discharge the rubber compound and press it into sheets.

10. A lunar rover tire, characterized in that: The non-tread portion of the tire is made of metal, and the tread is prepared by vulcanizing the tread rubber composition according to any one of claims 1 to 8.

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