Rubber basketball inner liner aging-resistant crosslinking modification treatment method

Abstract

The application belongs to the technical field of rubber material modification, and discloses an anti-aging cross-linking modification treatment method for a rubber basketball inner liner, which comprises the following steps: step 1, pretreatment; step 2, preparation of a composite cross-linking agent; step 3, mixing; step 4, sectional cross-linking; step 5, gradient vulcanization; step 6, post-treatment; and step 7, performance detection. The application adopts a dynamic disulfide bond-hydrogen bond double cross-linking system and rare earth composite modification synergistic effect, breaks through the technical bottleneck of traditional single cross-linking and single modification, the double cross-linking system can form a dense and stable three-dimensional cross-linking network, the mechanical properties and fatigue resistance of the inner liner are improved, the rare earth modifier can capture aging free radicals, tea polyphenol extract and nano titanium dioxide form a double anti-aging protection, the three are synergistic, the anti-aging performance of the inner liner is greatly improved compared with the existing traditional process, the service life is significantly prolonged compared with the existing product, and the problems of easy aging and elastic attenuation of the existing inner liner are solved.

Description

Technical Field

[0001] This invention belongs to the field of rubber material modification technology, specifically a method for aging-resistant crosslinking modification of rubber basketball bladders. Background Technology

[0002] The rubber basketball bladder is a core component of the basketball, and its performance directly determines the basketball's elasticity, airtightness, lifespan, and user experience. Currently, most rubber basketball bladders on the market are made from a single base material of natural or synthetic rubber, prepared using a traditional sulfur cross-linking process. This process has significant technical limitations: On the one hand, traditional cross-linking systems are mostly single sulfur cross-linking, with loose cross-linking structure and insufficient cross-linking density. As a result, the inner bladder is prone to oxidation aging, thermal aging, and fatigue aging during long-term use due to factors such as temperature changes, ultraviolet radiation, and repeated impacts. This leads to problems such as surface cracking, loss of elasticity, and decreased airtightness, which seriously shortens the service life of the basketball. On the other hand, traditional modification processes often use a single antioxidant, which has limited anti-aging effect. In addition, some modifiers pose environmental risks. Furthermore, the process parameters are poorly controlled, resulting in poor performance stability of the inner liner and large batch-to-batch errors.

[0003] While some existing technologies exist for modifying rubber bladders, such as using rare earth modification or silane coupling agents, most suffer from complex modification processes, unclear parameters, and a lack of a synergistic modification system, making it difficult to simultaneously achieve good aging resistance, mechanical properties, and airtightness. For example, some technologies use single rare earth oxide modification, which can improve aging resistance to some extent, but the compatibility between rare earth oxides and rubber substrates is poor, easily leading to agglomeration and affecting the elasticity and uniformity of the bladder. Other technologies use a single dynamic crosslinking system, which can improve recyclability, but the improvement in aging resistance is limited and cannot meet the requirements for long-term use of basketball bladders.

[0004] In addition, existing modification processes are mostly single-temperature crosslinking and single-temperature vulcanization, which leads to insufficient crosslinking reaction and uneven vulcanization, further affecting the aging resistance and service life of the inner liner.

[0005] Based on this, a method for aging-resistant crosslinking modification of rubber basketball bladders was designed. Summary of the Invention

[0006] In view of the above situation and to overcome the defects of the prior art, the present invention provides an aging-resistant crosslinking modification treatment method for rubber basketball bladders, which effectively solves the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for aging-resistant crosslinking modification of rubber basketball bladders, comprising the following steps: Step 1: Pretreatment: Select a blend of natural rubber and styrene-butadiene rubber as the substrate, add a pretreatment agent and activate it at a constant temperature of 55-65℃, a rotation speed of 200-250 rpm, and an activation time of 30-45 minutes. Then, perform vacuum dehydration at a temperature of 70-80℃, a vacuum degree of 0.06-0.08 MPa, and a dehydration time of 20-30 minutes to obtain an activated rubber substrate. The pretreatment agent is a mixture of nano-titanium dioxide, tea polyphenol extract, and anhydrous ethanol, wherein the mass fraction of nano-titanium dioxide is 3-5%, the mass fraction of tea polyphenol extract is 1-2%, the mass fraction of anhydrous ethanol is 93-96%, and the mass ratio of the pretreatment agent to the rubber substrate is 1:18-22. Step 2, Preparation of composite crosslinking agent: The dynamic disulfide bond crosslinking agent 4,4'-diaminodiphenyl disulfide, the hydrogen bond crosslinking agent 3-amino-1,2,4-triazole, the rare earth modifier cerium nitrate, and the silane coupling agent KH560 are mixed, and deionized water is added and stirred to disperse. The stirring temperature is 40-50℃, the speed is 300-350 rpm, and the stirring time is 25-35 minutes. Then, the temperature is raised to 60-70℃ and the reaction is maintained for 15-20 minutes. After cooling to room temperature, the composite crosslinking agent is obtained. The mass ratio of each component in the composite crosslinking agent is 4,4'-diaminodiphenyl disulfide:3-amino-1,2,4-triazole:cerium nitrate:silane coupling agent KH560:deionized water = 8-10:4-6:5-7:2-3:80-90. Step 3, Mixing: Add the activated rubber substrate obtained in Step 1 to a mixer and preheat at a constant temperature for 5-8 minutes (70-80℃). Then add the composite crosslinking agent prepared in Step 2, as well as the antioxidant, accelerator, and softener, and perform segmented mixing. The first stage mixing temperature is 80-90℃, the rotation speed is 250-300 rpm, and the mixing time is 8-10 minutes. The second stage mixing temperature is 95-105℃, the rotation speed is 300-350 rpm, and the mixing time is 5-7 minutes. After mixing, discharge the rubber compound and cool it to 40-50℃ to obtain the modified compound. The mass ratio of the composite crosslinking agent to the activated rubber substrate is 1:12-15, and the amounts of antioxidant, accelerator, and softener added are 1.5-2.5%, 1.0-1.5%, and 3-5% of the mass of the activated rubber substrate, respectively. Step 4, Segmented Crosslinking: Place the modified compound obtained in Step 3 into a crosslinking machine for segmented crosslinking treatment; the first stage crosslinking temperature is 110-120℃, the pressure is 1.2-1.5MPa, and the crosslinking time is 15-20 minutes; the second stage crosslinking temperature is 130-140℃, the pressure is 1.6-1.8MPa, and the crosslinking time is 10-15 minutes; during the segmented crosslinking process, the crosslinking machine speed is maintained at 50-80 rpm to ensure uniform crosslinking; Step 5, Gradient vulcanization: Place the segmented cross-linked rubber compound into a vulcanizing machine and use a gradient temperature vulcanization process; the first stage heats up to 145-155℃ and holds for 20-25 minutes; the second stage heats up to 160-170℃ and holds for 15-20 minutes; the third stage cools down to 120-130℃ and holds for 10-15 minutes; the pressure is maintained at 1.8-2.0 MPa during vulcanization. After vulcanization, allow it to cool naturally to room temperature to obtain the vulcanized rubber blank. Step 6, Post-processing: The vulcanized rubber blank obtained in Step 5 is subjected to surface grinding and edge trimming. The grinding speed is 150-200 rpm and the grinding time is 3-5 minutes. After trimming, vacuum setting is performed at a setting temperature of 60-70℃, a vacuum degree of 0.07-0.09MPa, and a setting time of 15-20 minutes. Subsequently, an anti-aging coating is applied to the surface with a coating thickness of 0.03-0.05mm. After coating, constant temperature drying is performed at a drying temperature of 80-90℃ and a drying time of 10-15 minutes to obtain the crude rubber basketball inner bladder. Step 7, Performance Testing: The crude rubber basketball bladder is tested for aging resistance, mechanical properties, and air tightness. If the test is qualified, it is a finished product; if the test is unqualified, return to step 3 for re-mixing and modification.

[0008] Preferably, the mass ratio of natural rubber to styrene-butadiene rubber in step 1 is 7:3-6:4, and the Mooney viscosity of the blended substrate is 45-55 mL (1+4) 100°C.

[0009] Preferably, the antioxidant in step 3 is a compound of antioxidant MB and antioxidant 4010NA in a mass ratio of 1:1.5-2; The accelerator is a compound of accelerator TMTD and accelerator CZ, with a mass ratio of 1:2-3; The softener is a compound of dibutyl phthalate and naphthenic oil in a mass ratio of 1:1.

[0010] Preferably, the surface anti-aging coating in step 6 is a composite coating of polysiloxane and nano zinc oxide, wherein the mass fraction of nano zinc oxide is 5-8%.

[0011] Preferably, the aging resistance test in step 7 includes thermal aging test, ultraviolet aging test, and fatigue aging test; the thermal aging test condition is to place at a constant temperature of 100℃ for 72 hours, and the tensile strength retention effect is good after aging; the ultraviolet aging test condition is to use an ultraviolet lamp with a power of 300W and an irradiation time of 120 hours, and the surface shows no obvious cracks and the elastic recovery effect is good after aging; the fatigue aging test condition is to repeatedly compress and stretch 10,000 times, and the airtightness is well maintained after aging.

[0012] Preferably, in step 4, during the segmented crosslinking process, after each segment of crosslinking is completed, the temperature is cooled to 100-110℃ using air cooling before proceeding to the next segment of crosslinking.

[0013] Preferably, in step 5, during the gradient vulcanization process, the heating rate is controlled at 2-3℃ / minute, and the cooling rate is controlled at 1-2℃ / minute.

[0014] Preferably, after vacuum dehydration in step 1, the moisture content of the rubber substrate is ≤0.5%.

[0015] Preferably, after the mixing in step 3, the uniformity error of the modified compound is ≤5%, and there are no obvious particulate impurities.

[0016] Preferably, after vacuum shaping in step 6, the dimensional error of the rubber basketball bladder is ≤0.1mm.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention utilizes a dynamic disulfide-hydrogen bond dual crosslinking system and rare earth composite modification to overcome the technical bottlenecks of traditional single crosslinking and single modification. The dual crosslinking system can form a dense and stable three-dimensional crosslinking network, improving the mechanical properties and fatigue resistance of the inner liner. The rare earth modifier can capture aging free radicals, and the tea polyphenol extract and nano titanium dioxide form a dual anti-aging protection. The three work synergistically to significantly improve the anti-aging performance of the inner liner compared to existing traditional processes and significantly extend its service life compared to existing products, thus solving the problems of easy aging and elasticity decay of existing inner liners. 2. This invention replaces the traditional single-temperature crosslinking and vulcanization process with a segmented crosslinking and gradient vulcanization process, which can ensure sufficient crosslinking reaction and uniform vulcanization, avoid insufficient or excessive crosslinking, and improve the stability of the inner liner performance. At the same time, the process steps are simple, no complex equipment is required, and it can be directly adapted to existing industrial production lines, reducing production costs. 3. This invention is environmentally friendly and efficient. The pretreatment agent uses natural tea polyphenol extract and nano titanium dioxide, which are free of toxic and harmful substances. The components of the composite crosslinking agent are all environmentally friendly and pollution-free. The entire process has no pollutant emissions and meets the requirements of green production. At the same time, the modified inner liner can be recycled, reducing resource waste and improving resource utilization. 4. The rubber basketball bladder modified by this invention not only has significantly improved aging resistance, but also has excellent mechanical properties and airtightness, which can meet the needs of professional competitive basketballs, while also taking into account daily recreational use, making it widely applicable. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0019] In the attached diagram: Figure 1 This is a schematic flowchart of the aging-resistant crosslinking modification treatment method for the rubber basketball bladder of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Depend on Figure 1 This invention relates to a method for aging-resistant crosslinking modification of rubber basketball bladders, comprising the following steps: Step 1: Preprocessing A blend of natural rubber and styrene-butadiene rubber (SBR) is selected as the base material, with a mass ratio of natural rubber to SBR of 7:3-6:4. The Mooney viscosity of the blend base material is 45-55 mL (1+4) at 100℃. This ratio ensures both the elasticity and toughness of the inner liner and improves the basic aging resistance of the base material, avoiding the shortcomings of a single base material. A pretreatment agent is added to the blend base material, and it is placed in a stirrer for constant temperature activation. The activation temperature is controlled at 55-65℃, the rotation speed is 200-250 rpm, and the activation time is 30-45 minutes. Through activation treatment, the active sites of the rubber molecular chains can be opened, improving the efficiency and uniformity of subsequent cross-linking reactions.

[0022] The pretreatment agent is a mixture of nano-titanium dioxide, tea polyphenol extract, and anhydrous ethanol, wherein the mass fraction of nano-titanium dioxide is 3-5%, the mass fraction of tea polyphenol extract is 1-2%, and the mass fraction of anhydrous ethanol is 93-96%. Nano-titanium dioxide has excellent UV shielding properties, which can effectively block the damage of ultraviolet rays to rubber molecules. Tea polyphenol extract is a natural antioxidant that can inhibit the oxidative aging of rubber. The two work synergistically to build a basic aging-resistant protection for the rubber substrate in advance. The mass ratio of the pretreatment agent to the rubber substrate is 1:18-22. This ratio can ensure the pretreatment effect without affecting the original properties of the rubber substrate.

[0023] After activation, the rubber substrate is placed in a vacuum drying oven for vacuum dehydration. The dehydration temperature is 70-80℃, the vacuum degree is 0.06-0.08MPa, and the dehydration time is 20-30 minutes to ensure that the moisture content of the rubber substrate is ≤0.5%. This moisture content can effectively prevent moisture from affecting the subsequent crosslinking reaction and vulcanization effect. After dehydration, it is taken out and cooled to room temperature to obtain the activated rubber substrate.

[0024] Step 2: Preparation of composite crosslinking agent A composite crosslinking agent was prepared by using a dynamic disulfide bond-hydrogen bond dual crosslinking system, combined with rare earth modifiers and silane coupling agents, to achieve synergistic reinforcement of the crosslinking structure and improve aging resistance. The specific preparation process is as follows: 4,4'-diaminodiphenyl disulfide, a dynamic disulfide crosslinking agent, 3-amino-1,2,4-triazole, a rare earth modifier, cerium nitrate, and a silane coupling agent, KH560, are mixed in proportion, deionized water is added, and the mixture is placed in a stirrer and stirred to disperse.

[0025] The mass ratio of each component in the composite crosslinking agent is 4,4'-diaminodiphenyl disulfide: 3-amino-1,2,4-triazole: cerium nitrate: silane coupling agent KH560: deionized water = 8-10: 4-6: 5-7: 2-3: 80-90. This ratio can achieve synergistic effects between the dual crosslinking system and rare earth modification. 4,4'-diaminodiphenyl disulfide can form dynamic disulfide bonds, giving the crosslinking network good reversibility and fatigue resistance. 3-amino-1,2,4-triazole can form hydrogen bonds, enhancing the stability of the crosslinking network. Cerium nitrate, as a rare earth modifier, can capture free radicals generated during rubber aging due to its special electronic layer structure, thus delaying the aging process. Silane coupling agent KH560 can improve the compatibility of each component with the rubber substrate and avoid agglomeration.

[0026] The stirring and dispersion conditions are as follows: stirring temperature 40-50℃, stirring speed 300-350 rpm, stirring time 25-35 minutes, which can ensure that the components are evenly dispersed and there is no obvious agglomeration; then the mixture is heated to 60-70℃ and kept at this temperature for 15-20 minutes to allow the components to react fully and form a stable composite crosslinking system; after the reaction is completed, it is naturally cooled to room temperature to obtain the composite crosslinking agent for later use.

[0027] Step 3, Mixing Add the activated rubber substrate obtained in step 1 into a mixer and preheat it at a constant temperature for 5-8 minutes at 70-80℃. The purpose of preheating is to soften the rubber substrate and facilitate uniform mixing in the subsequent process. After preheating, add the composite crosslinking agent prepared in step 2, as well as antioxidants, accelerators, and softeners, and perform segmented mixing. Segmented mixing can avoid problems such as uneven dispersion of crosslinking agents and breakage of rubber molecular chains caused by mixing at a single temperature, thus ensuring the uniformity and performance stability of the mixed rubber.

[0028] The mass ratio of the composite crosslinking agent to the activated rubber substrate is 1:12-15. This ratio ensures sufficient crosslinking reaction while avoiding excessive crosslinking agent that could lead to an overly hard inner liner and reduced elasticity. The amounts of antioxidant, accelerator, and softener added are 1.5-2.5%, 1.0-1.5%, and 3-5% of the mass of the activated rubber substrate, respectively. This amount of addition can balance processing performance and finished product performance.

[0029] The antioxidant is a compound of antioxidant MB and antioxidant 4010NA in a mass ratio of 1:1.5-2. The two work synergistically to simultaneously inhibit oxidative aging and ozone aging of rubber, improving aging resistance. This compound ratio has a better antioxidant effect than a single antioxidant. The accelerator is a compound of accelerator TMTD and accelerator CZ in a mass ratio of 1:2-3. It can accelerate the rate of crosslinking and vulcanization reactions, reduce reaction temperature, and save energy. This compound ratio can avoid over-vulcanization caused by excessive accelerator. The softener is a compound of dibutyl phthalate and naphthenic oil in a mass ratio of 1:1. It can improve the processing performance of rubber base material and enhance the flexibility and uniformity of the compound.

[0030] Specific parameters for staged mixing: The first stage mixing temperature is 80-90℃, the rotation speed is 250-300 rpm, and the mixing time is 8-10 minutes, mainly to achieve the initial dispersion of each component; the second stage mixing temperature is 95-105℃, the rotation speed is 300-350 rpm, and the mixing time is 5-7 minutes, mainly to achieve the deep dispersion and initial cross-linking of each component; this staged mixing can avoid uneven mixing or over-mixing. After mixing, the rubber compound is discharged and naturally cooled to 40-50℃ to obtain the modified compound. The uniformity error of the modified compound is required to be ≤5%, with no obvious particulate impurities.

[0031] Step 4: Segmented crosslinking The modified compound obtained in step 3 is placed in a crosslinking machine for segmented crosslinking. Segmented crosslinking can achieve the gradual progress of the crosslinking reaction, avoiding problems such as uneven crosslinking and insufficient crosslinking density caused by single-temperature crosslinking. At the same time, it can control the structure of the crosslinking network and improve the mechanical properties and aging resistance of the inner liner. Compared with the traditional single-temperature crosslinking, this process has significantly improved the crosslinking uniformity.

[0032] Specific parameters for segmented crosslinking: The first stage crosslinking temperature is 110-120℃, the pressure is 1.2-1.5MPa, and the crosslinking time is 15-20 minutes. This stage mainly achieves the initial crosslinking of rubber molecular chains and composite crosslinking agents, forming a basic crosslinking network. The second stage crosslinking temperature is 130-140℃, the pressure is 1.6-1.8MPa, and the crosslinking time is 10-15 minutes. This stage achieves deep crosslinking, increases the crosslinking density, and strengthens the stability of the crosslinking network.

[0033] During the segmented crosslinking process, the crosslinking machine speed is maintained at 50-80 rpm to ensure uniform crosslinking reaction. After each segment of crosslinking is completed, the temperature is cooled to 100-110℃ by air cooling before the next segment of crosslinking is carried out. This avoids sudden temperature changes that may cause the crosslinking network to break and affect the crosslinking effect. This cooling method can effectively protect the integrity of the crosslinking network structure.

[0034] Step 5: Gradient vulcanization The segmented cross-linked rubber compound is placed in a vulcanizing machine and a gradient temperature vulcanization process is adopted. Gradient vulcanization can avoid problems such as insufficient vulcanization, over-vulcanization or uneven vulcanization caused by single temperature vulcanization. At the same time, it can further strengthen the cross-linked network and improve the aging resistance, mechanical properties and airtightness of the inner liner. Compared with the traditional single temperature vulcanization, the finished product qualification rate is significantly improved.

[0035] Specific parameters for gradient vulcanization: The first stage involves heating to 145-155℃ and holding for 20-25 minutes. This stage primarily initiates the vulcanization reaction and strengthens the cross-linking network. The second stage involves heating to 160-170℃ and holding for 15-20 minutes. This stage achieves deep vulcanization, improving the hardness and toughness of the vulcanized rubber. The third stage involves cooling to 120-130℃ and holding for 10-15 minutes. This stage ensures a smooth end to the vulcanization reaction, reducing vulcanization stress and preventing problems such as deformation and cracking of the inner liner. This gradient ensures a smooth vulcanization reaction and improves the stability of the finished product's performance.

[0036] During the vulcanization process, the pressure is maintained at 1.8-2.0 MPa, the heating rate is controlled at 2-3℃ / min, and the cooling rate is controlled at 1-2℃ / min to ensure a stable vulcanization process. After vulcanization, the product is naturally cooled to room temperature to obtain the vulcanized rubber blank.

[0037] Step 6, Post-processing Post-processing mainly includes surface polishing, trimming, vacuum shaping, and surface anti-aging coating treatment, with the aim of improving the appearance quality, dimensional accuracy, and aging resistance of the inner liner.

[0038] First, place the vulcanized rubber blank obtained in step 5 into a grinding machine for surface grinding. The grinding speed is 150-200 rpm, and the grinding time is 3-5 minutes to remove burrs, impurities, and uneven parts from the surface of the rubber blank, so that the inner liner surface is smooth and flat. After grinding, trim the edges to remove excess rubber edges and ensure that the dimensions of the inner liner meet the design requirements.

[0039] After trimming, the inner bladder is placed in a vacuum forming chamber for vacuum forming at a temperature of 60-70℃ and a vacuum level of 0.07-0.09MPa for 15-20 minutes to ensure dimensional stability with a tolerance of ≤0.1mm, meeting the requirements for basketball inner bladders. After forming, an anti-aging coating is applied to the surface of the bladder. This coating is a composite of polysiloxane and nano-zinc oxide, with a nano-zinc oxide mass fraction of 5-8%. This ratio achieves optimal UV shielding and weather resistance. Polysiloxane has excellent weather resistance and water resistance, while nano-zinc oxide further enhances the UV shielding effect. The two work synergistically to form dual anti-aging protection. The coating thickness is controlled at 0.03-0.05mm. After coating, the bladder is placed in a constant temperature drying oven at 80-90℃ for 10-15 minutes to ensure firm adhesion, resulting in a rough rubber basketball inner bladder.

[0040] Step 7, Performance Testing Comprehensive performance testing is conducted on the crude rubber basketball bladder to ensure that the finished product meets the quality requirements. Testing items include aging resistance, mechanical properties, and airtightness. Specific testing standards are as follows. All testing standards are formulated with reference to relevant national standards for rubber products (GB / T 528-2009, GB / T 3512-2014, etc.), and the testing methods all adopt the corresponding national standard testing methods. 1) Aging resistance testing: including thermal aging test, ultraviolet aging test, and fatigue aging test; thermal aging test conditions are constant temperature of 100℃ for 72 hours, and the tensile strength retention effect is good after aging; ultraviolet aging test conditions are ultraviolet lamp power of 300W and irradiation time of 120 hours, and the surface shows no obvious cracks and the elastic recovery effect is good after aging; fatigue aging test conditions are repeated compression-tension 10,000 times, and the air tightness is maintained well after aging. 2) Mechanical property testing: The tensile strength, elongation at break, Shore hardness and elastic recovery rate all meet the design requirements, with the elastic recovery effect being excellent; 3) Air tightness test: Inflate the inner liner to the standard pressure and leave it for 24 hours. The pressure drop should meet the design requirements and the air tightness should remain stable.

[0041] Once the test is passed, it becomes the finished rubber basketball bladder; if the test fails, return to step 3 for re-mixing and modification until the test is passed. Example 1:

[0042] This invention relates to a method for aging-resistant crosslinking modification of rubber basketball bladders, comprising the following steps: Step 1, Pretreatment: Select a blend of natural rubber and styrene-butadiene rubber (mass ratio 7:3) with a Mooney viscosity of 45 mL (1+4) at 100°C; add a pretreatment agent (3% nano titanium dioxide, 1% tea polyphenol extract, and 96% anhydrous ethanol) to the blend, with a mass ratio of pretreatment agent to rubber substrate of 1:18; place it in a stirrer and activate it at 55°C and 200 rpm for 30 minutes; then place it in a vacuum drying oven and dehydrate it at 70°C and 0.06 MPa for 20 minutes until the moisture content is 0.4%; cool it to room temperature to obtain the activated rubber substrate.

[0043] Step 2, Preparation of composite crosslinking agent: Mix 4,4'-diaminodiphenyl disulfide, 3-amino-1,2,4-triazole, cerium nitrate, silane coupling agent KH560 and deionized water in a mass ratio of 8:4:5:2:80; stir and disperse at 40℃ and 300 rpm for 25 minutes; heat to 60℃ and keep warm for 15 minutes; cool to room temperature to obtain composite crosslinking agent.

[0044] Step 3, Mixing: Add the activated rubber base material to the internal mixer and preheat at 70°C for 5 minutes; add the composite crosslinking agent (mass ratio of 1:12 to the activated rubber base material), antioxidant (antioxidant MB: antioxidant 4010NA = 1:1.5, addition amount 1.5%), accelerator (accelerator TMTD: accelerator CZ = 1:2, addition amount 1.0%), and softener (dibutyl phthalate: naphthenic oil = 1:1, addition amount 3%); mix at 80°C and 250 rpm for 8 minutes in the first stage, and at 95°C and 300 rpm for 5 minutes in the second stage; cool to 40°C to obtain the modified compound with a uniformity error of 4%.

[0045] Step 4, Segmented crosslinking: Place the modified compound into the crosslinking machine. Crosslink for 15 minutes at 110℃, 1.2MPa, and 50 rpm for the first stage; then air cool to 100℃. Crosslink for 10 minutes at 130℃, 1.6MPa, and 50 rpm for the second stage.

[0046] Step 5, Gradient vulcanization: Place the product in a vulcanizing machine. In the first stage, heat the product to 145°C and hold for 20 minutes. In the second stage, heat the product to 160°C and hold for 15 minutes. In the third stage, cool the product to 120°C and hold for 10 minutes. Maintain a pressure of 1.8 MPa, a heating rate of 2°C / minute, and a cooling rate of 1°C / minute. Cool the product to room temperature to obtain a vulcanized rubber blank.

[0047] Step 6, Post-processing: Grind at 150 rpm for 3 minutes, trim the edges; Vacuum set at 60℃ and 0.07MPa for 15 minutes, with a dimensional error of 0.08mm; Coat the surface with a 0.03mm composite anti-aging coating (5% nano zinc oxide); Dry at 80℃ for 10 minutes to obtain the rough inner liner.

[0048] Step 7, Performance Testing: The product is tested using national standard testing methods. All performance indicators meet the design requirements, and the product is qualified. Example 2:

[0049] This invention relates to a method for aging-resistant crosslinking modification of rubber basketball bladders, comprising the following steps: Step 1, Pretreatment: Select a blend of natural rubber and styrene-butadiene rubber (mass ratio 6.5:3.5) with a Mooney viscosity of 50 mL (1+4) at 100°C; add a pretreatment agent (4% nano-titanium dioxide, 1.5% tea polyphenol extract, and 94.5% anhydrous ethanol) to the blend, with a mass ratio of pretreatment agent to rubber substrate of 1:20; place it in a stirrer and activate it at 60°C and 220 rpm for 38 minutes; then place it in a vacuum drying oven and dehydrate it at 75°C and 0.07 MPa for 25 minutes until the moisture content is 0.3%; cool it to room temperature to obtain the activated rubber substrate.

[0050] Step 2, Preparation of composite crosslinking agent: Mix 4,4'-diaminodiphenyl disulfide, 3-amino-1,2,4-triazole, cerium nitrate, silane coupling agent KH560 and deionized water in a mass ratio of 9:5:6:2.5:85; stir and disperse at 320 rpm for 30 minutes at 45°C; heat to 65°C and maintain the temperature for 18 minutes; cool to room temperature to obtain the composite crosslinking agent.

[0051] Step 3, Mixing: Add the activated rubber base material to the internal mixer and preheat at 75°C for 6 minutes; add the composite crosslinking agent (mass ratio of activated rubber base material 1:13.5), antioxidant (antioxidant MB:antioxidant 4010NA=1:1.8, addition amount 2.0%), accelerator (accelerator TMTD:accelerator CZ=1:2.5, addition amount 1.2%), and softener (dibutyl phthalate:naphthenic oil=1:1, addition amount 4%); mix at 85°C and 280 rpm for 9 minutes in the first stage, and at 100°C and 320 rpm for 6 minutes in the second stage; cool to 45°C to obtain the modified compound with a uniformity error of 3%.

[0052] Step 4, Segmented crosslinking: Place the modified compound into the crosslinking machine. Crosslink for 18 minutes at 115℃, 1.3MPa, and 65 rpm for the first stage; then air cool to 105℃. Crosslink for 12 minutes at 135℃, 1.7MPa, and 65 rpm for the second stage.

[0053] Step 5, Gradient vulcanization: Place the product in a vulcanizing machine. In the first stage, heat the product to 150°C and hold for 22 minutes. In the second stage, heat the product to 165°C and hold for 18 minutes. In the third stage, cool the product to 125°C and hold for 12 minutes. Maintain a pressure of 1.9 MPa, a heating rate of 2.5°C / min, and a cooling rate of 1.5°C / min. Cool the product to room temperature to obtain a vulcanized rubber blank.

[0054] Step 6, Post-processing: Grind at 180 rpm for 4 minutes, trim the edges; Vacuum set at 65℃ and 0.08MPa for 18 minutes, with a dimensional error of 0.07mm; Coat the surface with a 0.04mm composite anti-aging coating (6.5% nano zinc oxide); Dry at 85℃ for 12 minutes to obtain the rough inner liner.

[0055] Step 7, Performance Testing: The product is tested using national standard testing methods. All performance indicators meet the design requirements, and the product is qualified. Example 3:

[0056] This invention relates to a method for aging-resistant crosslinking modification of rubber basketball bladders, comprising the following steps: Step 1, Pretreatment: Select a blend of natural rubber and styrene-butadiene rubber (mass ratio 6:4) with a Mooney viscosity of 55 mL (1+4) at 100°C; add a pretreatment agent (5% nano-titanium dioxide, 2% tea polyphenol extract, and 93% anhydrous ethanol) to the blend, with a mass ratio of pretreatment agent to rubber substrate of 1:22; place it in a stirrer and activate it at 65°C and 250 rpm for 45 minutes; then place it in a vacuum drying oven and dehydrate it at 80°C and 0.08 MPa for 30 minutes until the moisture content is 0.2%; cool it to room temperature to obtain the activated rubber substrate.

[0057] Step 2, Preparation of composite crosslinking agent: Mix 4,4'-diaminodiphenyl disulfide, 3-amino-1,2,4-triazole, cerium nitrate, silane coupling agent KH560 and deionized water in a mass ratio of 10:6:7:3:90; stir and disperse at 50℃ and 350 rpm for 35 minutes; heat to 70℃ and keep warm for 20 minutes; cool to room temperature to obtain composite crosslinking agent.

[0058] Step 3, Mixing: Add the activated rubber base material to the internal mixer and preheat at 80°C for 8 minutes; add the composite crosslinking agent (mass ratio of 1:15 to the activated rubber base material), antioxidant (antioxidant MB: antioxidant 4010NA = 1:2, addition amount 2.5%), accelerator (accelerator TMTD: accelerator CZ = 1:3, addition amount 1.5%), and softener (dibutyl phthalate: naphthenic oil = 1:1, addition amount 5%); mix at 90°C and 300 rpm for 10 minutes in the first stage, and at 105°C and 350 rpm for 7 minutes in the second stage; cool to 50°C to obtain the modified compound with a uniformity error of 2%.

[0059] Step 4, Segmented crosslinking: Place the modified compound into a crosslinking machine. Crosslink for 20 minutes at 120℃, 1.5MPa, and 80 rpm for the first stage; then air-cool to 110℃. Crosslink for 15 minutes at 140℃, 1.8MPa, and 80 rpm for the second stage.

[0060] Step 5, Gradient vulcanization: Place the product in a vulcanizing machine. In the first stage, heat the product to 155°C and hold for 25 minutes. In the second stage, heat the product to 170°C and hold for 20 minutes. In the third stage, cool the product to 130°C and hold for 15 minutes. Maintain a pressure of 2.0 MPa, a heating rate of 3°C / minute, and a cooling rate of 2°C / minute. Cool the product to room temperature to obtain a vulcanized rubber blank.

[0061] Step 6, Post-processing: Grind at 200 rpm for 5 minutes, trim the edges; Vacuum set at 70℃ and 0.09MPa for 20 minutes, with a dimensional error of 0.06mm; Coat the surface with a 0.05mm composite anti-aging coating (8% nano zinc oxide); Dry at 90℃ for 15 minutes to obtain the rough inner liner.

[0062] Step 7, Performance Testing: The product is tested using national standard testing methods. All performance indicators meet the design requirements, and the product is qualified.

[0063] Comparative test A rubber basketball bladder prepared using the existing traditional sulfur crosslinking process (control group) was selected and compared with the bladder prepared in Example 2 of this invention (experimental group) for performance evaluation. All tests were conducted using the same national standard testing methods to ensure the objectivity and accuracy of the comparison results. The results showed that the experimental group outperformed the control group in all aspects, with significant improvements in aging resistance, mechanical properties, and airtightness. Specific test data are shown in the table below: It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the anti-aging crosslinking modification treatment of a rubber basketball inner liner, characterized in that, Includes the following steps: Step 1: Pretreatment: Select a blend of natural rubber and styrene-butadiene rubber as the substrate, add a pretreatment agent and activate it at a constant temperature of 55-65℃, a rotation speed of 200-250 rpm, and an activation time of 30-45 minutes. Then, perform vacuum dehydration at a temperature of 70-80℃, a vacuum degree of 0.06-0.08 MPa, and a dehydration time of 20-30 minutes to obtain an activated rubber substrate. The pretreatment agent is a mixture of nano-titanium dioxide, tea polyphenol extract, and anhydrous ethanol, wherein the mass fraction of nano-titanium dioxide is 3-5%, the mass fraction of tea polyphenol extract is 1-2%, the mass fraction of anhydrous ethanol is 93-96%, and the mass ratio of the pretreatment agent to the rubber substrate is 1:18-22. Step 2, Preparation of composite crosslinking agent: The dynamic disulfide bond crosslinking agent 4,4'-diaminodiphenyl disulfide, the hydrogen bond crosslinking agent 3-amino-1,2,4-triazole, the rare earth modifier cerium nitrate, and the silane coupling agent KH560 are mixed, and deionized water is added and stirred to disperse. The stirring temperature is 40-50℃, the speed is 300-350 rpm, and the stirring time is 25-35 minutes. Then, the temperature is raised to 60-70℃ and the reaction is maintained for 15-20 minutes. After cooling to room temperature, the composite crosslinking agent is obtained. The mass ratio of each component in the composite crosslinking agent is 4,4'-diaminodiphenyl disulfide:3-amino-1,2,4-triazole:cerium nitrate:silane coupling agent KH560:deionized water = 8-10:4-6:5-7:2-3:80-90. Step 3, Mixing: Add the activated rubber substrate obtained in Step 1 to a mixer and preheat at a constant temperature for 5-8 minutes (70-80℃). Then add the composite crosslinking agent prepared in Step 2, as well as the antioxidant, accelerator, and softener, and perform segmented mixing. The first stage mixing temperature is 80-90℃, the rotation speed is 250-300 rpm, and the mixing time is 8-10 minutes. The second stage mixing temperature is 95-105℃, the rotation speed is 300-350 rpm, and the mixing time is 5-7 minutes. After mixing, discharge the rubber compound and cool it to 40-50℃ to obtain the modified compound. The mass ratio of the composite crosslinking agent to the activated rubber substrate is 1:12-15, and the amounts of antioxidant, accelerator, and softener added are 1.5-2.5%, 1.0-1.5%, and 3-5% of the mass of the activated rubber substrate, respectively. Step 4, Segmented crosslinking: The modified compound obtained in step 3 is placed into a crosslinking machine for segmented crosslinking treatment; The first stage crosslinking temperature is 110-120℃, the pressure is 1.2-1.5MPa, and the crosslinking time is 15-20 minutes; The second stage crosslinking temperature is 130-140℃, the pressure is 1.6-1.8MPa, and the crosslinking time is 10-15 minutes. During the segmented crosslinking process, the crosslinking machine speed is maintained at 50-80 rpm to ensure uniform crosslinking. Step 5, Gradient vulcanization: Place the segmented cross-linked rubber compound into a vulcanizing machine and use a gradient temperature vulcanization process; the first stage heats up to 145-155℃ and holds for 20-25 minutes; the second stage heats up to 160-170℃ and holds for 15-20 minutes; the third stage cools down to 120-130℃ and holds for 10-15 minutes; the pressure is maintained at 1.8-2.0 MPa during vulcanization. After vulcanization, allow it to cool naturally to room temperature to obtain the vulcanized rubber blank. Step 6, Post-processing: The vulcanized rubber blank obtained in Step 5 is subjected to surface grinding and edge trimming. The grinding speed is 150-200 rpm and the grinding time is 3-5 minutes. After trimming, vacuum setting is performed at a setting temperature of 60-70℃, a vacuum degree of 0.07-0.09MPa, and a setting time of 15-20 minutes. Subsequently, an anti-aging coating is applied to the surface with a coating thickness of 0.03-0.05mm. After coating, constant temperature drying is performed at a drying temperature of 80-90℃ and a drying time of 10-15 minutes to obtain the crude rubber basketball inner bladder. Step 7, Performance Testing: The crude rubber basketball bladder is tested for aging resistance, mechanical properties, and air tightness. If the test is qualified, it is a finished product; if the test is unqualified, return to step 3 for re-mixing and modification.

2. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, The mass ratio of natural rubber to styrene-butadiene rubber in step 1 is 7:3-6:4, and the Mooney viscosity of the blended substrate is 45-55 mL (1+4) 100℃.

3. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, The antioxidant mentioned in step 3 is a compound of antioxidant MB and antioxidant 4010NA, with a mass ratio of 1:1.5-2; The accelerator is a compound of accelerator TMTD and accelerator CZ, with a mass ratio of 1:2-3; The softener is a compound of dibutyl phthalate and naphthenic oil in a mass ratio of 1:

1.

4. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, The surface anti-aging coating mentioned in step 6 is a composite coating of polysiloxane and nano zinc oxide, wherein the mass fraction of nano zinc oxide is 5-8%.

5. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, The aging resistance test described in step 7 includes thermal aging test, ultraviolet aging test, and fatigue aging test. The thermal aging test condition is to place the product at a constant temperature of 100℃ for 72 hours, and the tensile strength retention effect is good after aging. The ultraviolet aging test condition is to use an ultraviolet lamp with a power of 300W and an irradiation time of 120 hours, and the surface shows no obvious cracks and the elastic recovery effect is good after aging. The fatigue aging test condition is to repeatedly compress and stretch 10,000 times, and the airtightness is well maintained after aging.

6. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, In step 4, during the segmented crosslinking process, after each segment of crosslinking is completed, the temperature is lowered to 100-110℃ using air cooling before proceeding to the next segment of crosslinking.

7. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, In step 5, during the gradient vulcanization process, the heating rate is controlled at 2-3℃ / minute, and the cooling rate is controlled at 1-2℃ / minute.

8. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, After vacuum dehydration in step 1, the moisture content of the rubber substrate is ≤0.5%.

9. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, After the mixing in step 3, the uniformity error of the modified compound is ≤5%, and there are no obvious particulate impurities.

10. The method for aging-resistant crosslinking modification of rubber basketball bladder according to claim 1, characterized in that, After vacuum shaping in step 6, the dimensional error of the rubber basketball bladder is ≤0.1mm.

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