Application of environment-friendly tire regenerated rubber particles as asphalt road-building oil formula

Abstract

The invention discloses application of environment-friendly tire regenerated rubber particles as an asphalt road-building oil formula, rubber particles are endowed with a stable three-dimensional cross-linked network through rubber particle gradient distribution and a dynamic vulcanization technology, and the interface bonding effect of a silane coupling agent and nano SiO2 is combined, so that the high and low temperature performance of an asphalt mixture is remarkably improved, and the fatigue life of the asphalt mixture is remarkably prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of recycled rubber particles, and particularly to the use of an environment-friendly recycled rubber particle for tire as a formula of asphalt road oil. Background Art

[0002] Waste tires are a global environmental problem. Every year, more than 1.5 billion waste tires are discarded globally. Traditional landfill and incineration treatment methods not only occupy a large amount of land resources but also cause serious environmental pollution. For example, the emission concentration of volatile organic compounds (VOCs) during the incineration process is as high as 200 mg / m 3 above. With the improvement of environmental awareness and the promotion of the concept of circular economy, the resource utilization of waste tires has become a research hotspot. Among them, processing waste tires into recycled rubber particles and applying them to asphalt pavement materials can not only solve the problem of waste tire treatment but also improve the performance of asphalt pavements, with significant environmental benefits and economic value.

[0003] Currently, there are various technical solutions for the application of recycled rubber from waste tires in asphalt. CN111944321B discloses a highly viscous, semi-fused functional composite environment-friendly asphalt interface regenerant, which contains 10-20 parts of industrial waste rubber powder. By optimizing the main raw materials, the materials in the interface area have strong adhesion and high ductility deformation ability. CN118546538A proposes a road asphalt based on recycled rubber particles, including components such as 70%-85% of matrix asphalt and 5%-15% of recycled rubber particles. By adding recycled rubber particles and chemical modifiers to the matrix asphalt, the high-temperature stability and low-temperature crack resistance of the asphalt are significantly improved.

[0004] In terms of the treatment technology of recycled rubber particles, CN117402502A discloses a preparation method of a rubber asphalt material with self-recovering performance. In this method, rubber powder is blended with a microwave activator and then fused with matrix asphalt, and the self-recovering performance is achieved through microwave heating treatment. CN118126739B provides an environment-friendly rubber plasticizer and its preparation method and application, and this plasticizer can be used for the preparation of recycled rubber [4]. In addition, CN111704747A introduces an environment-friendly recycled material. By adding an activator and an activation auxiliary particle, the mercapto groups on the surface of the rubber powder can be effectively eliminated, preventing the reconnection of the broken disulfide bonds and polysulfide bonds on the surface of the rubber particles, and achieving the purpose of stabilizing the Mooney viscosity.

[0005] However, the existing technology still has the following technical problems in the application of recycled rubber particles from waste tires to asphalt road oil:

[0006] 1. The traditional preparation process of recycled rubber mainly adopts the high-temperature and high-pressure desulfurization process (220°C, 1.8 MPa). Under such process conditions, the main chain of rubber is prone to degradation, and the molecular weight retention rate usually does not exceed 60%, resulting in a significant decline in the mechanical properties of recycled rubber and making it difficult to meet the requirements of high-performance asphalt pavements.

[0007] 2. The interfacial compatibility between recycled rubber particles and asphalt is poor. When directly incorporated into asphalt, the dosage of rubber powder is limited (usually not exceeding 15%), and the mass loss rate is as high as more than 5% under harsh environments such as acid rain, seriously affecting the service life and performance stability of asphalt pavements.

[0008] 3. In the existing technologies, the surface treatment methods of recycled rubber particles are single, and it is difficult to simultaneously solve the problems of interfacial compatibility and environmental durability. Especially under high-dosage conditions, the performance of asphalt mixtures often fails to meet the engineering requirements.

[0009] 4. There is a lack of effective co-modification technologies, and the reinforcing and modifying effects of recycled rubber particles in asphalt cannot be fully exerted, resulting in unstable comprehensive performance of modified asphalt.

[0010] Therefore, there is an urgent need for the use of environmentally friendly tire recycled rubber particles as an asphalt road construction oil formula. Through technical means such as microwave pretreatment, dynamic vulcanization co-modification, and surface nano-coating, the compatibility between recycled rubber particles and asphalt is improved, and their dosage and stability in asphalt are enhanced, so as to achieve the high-value utilization of waste tires and the overall improvement of the performance of asphalt pavements. Summary of the Invention

[0011] The technical problems to be solved by the present invention are: to solve the problems of serious pollution in waste tire treatment and low resource utilization rate, as well as the degradation of the rubber main chain and poor interfacial compatibility of asphalt composites caused by existing recycled rubber technologies, and to achieve technical effects such as environmental protection and emission reduction, improving the utilization rate of rubber powder, and extending the service life of pavements.

[0012] To solve the above technical problems, the technical solution adopted by the present invention is: a use of environmentally friendly tire recycled rubber particles as an asphalt road construction oil formula, and the recycled rubber particles are prepared through the following steps:

[0013] Crush and screen waste tires into rubber powder particles with a size of 0.5 - 3 mm, and form a gradient distribution according to the mass percentage: 25% - 35% for 0.5 - 1 mm, 40% - 50% for 1 - 2 mm, and 25% - 35% for 2 - 3 mm;

[0014] Microwave pretreatment: Place the screened rubber powder particles in a microwave treatment device and treat them for 10 - 20 min under the conditions of a microwave frequency of 2400 - 2500 MHz and a power density of 0.7 - 1.0 kW / kg to obtain pretreated rubber powder;

[0015] Dynamic vulcanization: The pre-treated rubber powder reacts with a compound vulcanizing agent of 0.5% - 1.0% sulfur and 0.1% - 0.5% peroxide under shear conditions at 150 - 170 °C to form regenerated particles with a crosslinking density.

[0016] Surface nano-coating: The rubber powder is coated with a composite of a silane coupling agent and nano-SiO₂ with a particle size of 10 - 50 nm, so that the nano-SiO₂ particles are firmly attached to the surface of the rubber powder through the silane coupling agent, forming a uniform coating layer of 75 nm - 100 nm, and thus obtaining modified regenerated rubber particles.

[0017] The beneficial effects of the present invention are as follows: By using the setting of gradient pore sizes, small particles are used to fill the gaps between large particles, reducing the porosity of the mixture. Medium particles act as the main framework to bear the vehicle load stress, improving the dynamic stability. Large particles absorb the energy of crack propagation through elastic deformation, so that the porosity can be evenly distributed through gradient ratio, improving the dynamic stability. Then, microwave pretreatment is used to selectively break S-S / C-S bonds, avoiding excessive degradation of the main chain, so that the elastic recovery rate reaches more than 80%. Then, in combination with the compound of sulfur and DCP, sulfur forms a flexible three-dimensional network structure by forming polysulfide bonds (S-S / C-S), and DCP initiates a free radical reaction to generate carbon-carbon bonds (C-C), strengthening the crosslinking density and improving the thermal stability. Then, in combination with the surface coating of nano-SiO₂, the surface of SiO₂ is modified by a silane coupling agent (KH550 / KH570) to form a covalent bond with the rubber particles, forming a nano-SiO₂ coating layer, improving the interfacial bonding force, so that the tensile strength is above 0.85 MPa. And the nano-SiO₂ coating layer can block the penetration of acid rain, reducing the acid rain mass loss rate to less than 0.7%. At the same time, the gradient particle size reduces stress concentration, and the nano-SiO₂ coating layer fills the interfacial micro-defects, forming a double protection, so that the ultraviolet retention rate reaches more than 90%, extending the service life. Specific embodiments

[0018] To illustrate the technical content, the achieved objectives and the effects of the present invention in detail, the following is an illustration in combination with the embodiments.

[0019] The use of an environmentally friendly tire regenerated rubber particle as an asphalt road construction oil formula, and the regenerated rubber particle is prepared by the following steps:

[0020] The waste tires are crushed and screened into rubber powder particles of 0.5 - 3 mm, and a gradient distribution is formed according to the mass percentage: 0.5 - 1 mm accounts for 25% - 35%, 1 - 2 mm accounts for 40% - 50%, and 2 - 3 mm accounts for 25% - 35%.

[0021] Microwave pretreatment: Place the screened rubber powder particles in a microwave treatment device and treat them under the conditions of a microwave frequency of 2400 - 2500 MHz and a power density of 0.7 - 1.0 kW / kg for 10 - 20 minutes to obtain pretreated rubber powder;

[0022] Dynamic vulcanization: React the pretreated rubber powder with a compound vulcanizing agent of 0.5% - 1.0% sulfur and 0.1% - 0.5% peroxide under shear conditions at 150 - 170 °C to form regenerated particles with a crosslinking density;

[0023] Surface nano - coating: Use a silane coupling agent and nano - SiO₂ with a particle size of 10 - 50 nm for composite coating, so that the nano - SiO₂ particles are firmly attached to the surface of the rubber powder through the silane coupling agent, forming a uniform coating layer of 75 nm - 100 nm, that is, modified regenerated rubber particles are obtained.

[0024] Furthermore, the mass ratio of the three particle size gradients is 30%:40%:30%.

[0025] Furthermore, the dynamic vulcanizing agent is composed of a compound of 0.8% sulfur and 0.3% dicumyl peroxide.

[0026] Furthermore, the nano - SiO₂ coating layer is composed of a composite of a silane coupling agent and SiO₂ particles. Among them, the silane coupling agent is composed of a compound solution of KH550 and KH570, and the mass ratio of KH550 to KH570 is 1:1. The addition amount of the silane coupling agent is 3% of the total mass of the rubber powder, and the ratio of the total mass of the solid SiO₂ particles to the total mass of the silane coupling agent is 1:1.

[0027] Furthermore, the dosage of the modified regenerated rubber particles is 30% of the total mass of the asphalt road - building oil.

[0028] Example 1:

[0029] A preparation method of modified regenerated rubber particles, comprising the following steps:

[0030] Select waste tires and obtain initial rubber powder through a conventional crushing process. Screen out rubber powder particles with a particle size of 0.5 - 3 mm, among which those with a particle size of 0.5 - 1 mm account for 30%, those with a particle size of 1 - 2 mm account for 40%, and those with a particle size of 2 - 3 mm account for 30%, forming a gradient distribution.

[0031] Microwave pretreatment: Place the screened rubber powder in a microwave treatment device, set the microwave frequency to 2450 MHz, the power density to 0.8 kW / kg, and the treatment time to 15 minutes. During the microwave treatment process, the surface temperature of the rubber powder rises to 120 °C, causing partial breakage of the rubber molecular chains, increasing the active sites, and at the same time causing partial decomposition of the residual vulcanization system inside the rubber powder, creating conditions for subsequent dynamic vulcanization.

[0032] Dynamic vulcanization treatment: Transfer the microwave-pretreated rubber powder into a high-speed shear mixer, and add 0.8% sulfur and 0.3% dicumyl peroxide (DCP) as a compound vulcanization system. The rotation speed of the mixer is set at 150 r / min, and dynamic vulcanization is carried out at this shear rate. The treatment temperature is controlled at 160 °C, and the treatment time is 30 minutes. During this process, sulfur and peroxide act synergistically to re-crosslink the rubber molecular chains, forming a more stable network structure and improving the elastic recovery and thermal stability of the rubber powder.

[0033] Surface coating of nano-SiO2: Cool the dynamically vulcanized rubber powder to room temperature and transfer it into a surface treatment reactor. First, add a mixed solution of silane coupling agents KH550 and KH570 with a concentration of 3%, and soak for 2 hours to allow the silane coupling agent to fully contact the surface of the rubber powder. Subsequently, add nano-SiO2 sol (particle size 20 nm), and stir and react at 60 °C for 4 hours to make the nano-SiO2 particles firmly adhere to the surface of the rubber powder through the silane coupling agent, forming a uniform coating layer with a thickness of 75 nm. The treated rubber powder is washed and dried to obtain modified recycled rubber particles with a nano-SiO2 layer on the surface.

[0034] Example 2:

[0035] Preparation method of modified recycled rubber particles, including the following steps:

[0036] Select waste tires and obtain initial rubber powder through a conventional crushing process. Screen out rubber powder particles with a particle size of 0.5 - 3 mm, where the particle size of 0.5 - 1 mm accounts for 25%, 1 - 2 mm accounts for 45%, and 2 - 3 mm accounts for 30%, forming a gradient distribution.

[0037] Microwave pretreatment: Place the screened rubber powder in a microwave treatment device, set the microwave frequency at 2450 MHz, the power density at 0.8 kW / kg, and the treatment time at 20 minutes. During the microwave treatment, the surface temperature of the rubber powder rises to 130 °C, causing partial breakage of the rubber molecular chains, increasing the active sites, and simultaneously causing partial decomposition of the residual vulcanization system inside the rubber powder, creating conditions for subsequent dynamic vulcanization.

[0038] Dynamic vulcanization treatment: Transfer the microwave-pretreated rubber powder into a high-speed shear mixer, and add 1.0% sulfur and 0.5% dicumyl peroxide (DCP) as a compound vulcanization system. The rotation speed of the mixer is set at 180 r / min, and dynamic vulcanization is carried out at this shear rate. The treatment temperature is controlled at 170 °C, and the treatment time is 35 minutes. During this process, sulfur and peroxide act synergistically to re-crosslink the rubber molecular chains, forming a more stable network structure and improving the elastic recovery and thermal stability of the rubber powder.

[0039] Surface Coating of Nano-SiO₂: The dynamically vulcanized rubber powder was cooled to room temperature and transferred to a surface treatment reactor. First, a KH570 solution of silane coupling agent with a concentration of 3.5% was added, and the soaking time was 2.5 hours to ensure sufficient contact between the silane coupling agent and the surface of the rubber powder. Subsequently, nano-SiO₂ sol (particle size 25 nm) was added, and the mixture was stirred and reacted at 65 °C for 5 hours, enabling the nano-SiO₂ particles to firmly adhere to the surface of the rubber powder through the silane coupling agent, forming a uniform coating layer with a thickness of 100 nm. The treated rubber powder was washed and dried to obtain modified recycled rubber particles with a nano-SiO₂ layer coated on the surface.

[0040] Comparative Example 1:

[0041] Different from the preparation method of the modified recycled rubber particles in Example 1, the microwave pretreatment was omitted.

[0042] Comparative Example 2:

[0043] Different from the preparation method of the modified recycled rubber particles in Example 1, the surface coating of nano-SiO₂ was omitted.

[0044] Comparative Example 3:

[0045] Different from the preparation method of the modified recycled rubber particles in Example 1, only 1% of single sulfur was added during the dynamic vulcanization treatment, and dicumyl peroxide (DCP) was not added.

[0046] Comparative Example 4:

[0047] Different from the preparation method of the modified recycled rubber particles in Example 1, the initial rubber powder was prepared from waste tires through a conventional crushing process, and the particle size was screened to be 1 - 2 mm. The microwave pretreatment was replaced by a traditional high-temperature and high-pressure desulfurization method. Specifically, after the rubber powder was mixed evenly with the regenerant, it was placed in a closed high-pressure container, and direct steam with a pressure of 4.9 - 6.9 MPa was introduced for desulfurization and regeneration. Under high temperature conditions of 220 - 250 °C and high pressure, the fibers in the rubber powder were damaged, thereby achieving desulfurization. The surface coating of nano-SiO₂ was omitted.

[0048] Comparative Example 5:

[0049] Different from Example 1, the initial rubber powder had a single particle size of 1 - 2 mm.

[0050] Experimental Group:

[0051] The recycled rubber particles prepared in the above Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 5 were incorporated into 90# road petroleum asphalt at a mass ratio of 30%, and stirred and mixed at 175°C for 2 hours to fully blend the recycled rubber particles with the asphalt, forming a uniform modified asphalt material, namely asphalt road construction oil. The recycled rubber particles of Comparative Example 4 were incorporated into 90# road petroleum asphalt at a mass ratio of 15%, and stirred and mixed at 175°C for 2 hours to fully blend the recycled rubber particles with the asphalt, forming a uniform modified asphalt material, namely asphalt road construction oil.

[0052] The experimental group data of the content of recycled rubber particles in asphalt road construction oil are as follows:

[0053]

[0054]

[0055] Experimental detection indexes:

[0056] Dynamic stability (times / mm): Measured by T0719-2011 (rutting test). Specific conditions: 60°C, wheel pressure: 0.7 MPa.

[0057] Low-temperature bending strain energy (kJ / m 2 ): Measured by T0728-2000 (low-temperature small beam test).

[0058] Acid rain mass loss rate (%): Measured by JTG E20-2011 (immersion method). The simulated acid rain condition is a H2SO4 / HNO3 mixed solution with pH = 3.5 (volume ratio 3:1), soaking temperature 40°C, and the mass loss rate is tested.

[0059] Elastic recovery rate (%): Measured by ASTM D6084. Specific conditions: constant temperature at 25°C, loading stress 0.1 MPa, holding time 60 s, recovery time 30 s.

[0060] Ultraviolet aging retention rate (%): Measured by GB / T 3511-2008.

[0061] Performance comparison table of modified asphalt materials:

[0062]

[0063] It can be seen from the above performance comparison table that:

[0064] The performances of Example 1 and Example 2 are the best, which indicates that through the four steps of gradient particle size distribution, microwave pretreatment, dynamic vulcanization treatment and nano-SiO2 surface coating in this application, the compatibility of the interface between the recycled rubber particles and the asphalt is improved, the content of the rubber powder is increased, and the service life is extended.

[0065] The above are only embodiments of the present invention, and do not thereby limit the patent scope of the present invention. Any equivalent transformation made by using the content of the specification of the present invention, or directly or indirectly applied in related technical fields, shall equally be included in the patent protection scope of the present invention.

Claims

1. Use of an environment-friendly tire recycled rubber granule as an asphalt road construction oil formulation, characterized in that, The recycled rubber particles are prepared through the following steps: The waste tires are crushed and screened into rubber powder particles with a size of 0.5 - 3 mm, forming a gradient distribution with 25% - 35% of 0.5 - 1 mm, 40% - 50% of 1 - 2 mm, and 25% - 35% of 2 - 3 mm by mass percentage; Microwave pretreatment: The screened rubber powder particles are placed in a microwave treatment device and treated for 10 - 20 min under the conditions of a microwave frequency of 2400 - 2500 MHz and a power density of 0.7 - 1.0 kW / kg to obtain pretreated rubber powder; Dynamic vulcanization: The pretreated rubber powder reacts with a compound vulcanizing agent of 0.5% - 1.0% sulfur and 0.1% - 0.5% peroxide under the conditions of 150 - 170 °C and shear to form recycled particles with a crosslinking density; Surface nano - coating: The surface is coated with a composite of a silane coupling agent and nano - SiO2 with a particle size of 10 - 50 nm, so that the nano - SiO2 particles are firmly attached to the surface of the rubber powder through the silane coupling agent, forming a uniform coating layer of 75 nm - 100 nm, namely, the modified recycled rubber particles are obtained.

2. The use according to claim 1, characterized in that, The mass ratio of the three particle size gradients is 30%:40%:30%.

3. Use of the environment-friendly tire recycled rubber particles as an asphalt road construction oil formulation according to claim 1, characterized in that: The dynamic vulcanizing agent is composed of a compound of 0.8% sulfur and 0.3% dicumyl peroxide.

4. Use of the environment-friendly tire recycled rubber particles as an asphalt road construction oil formulation according to claim 1, characterized in that: The nano - SiO2 coating layer is composed of a composite of a silane coupling agent and SiO2 particles. The silane coupling agent is composed of a solution of KH550 and KH570, and the mass ratio of KH550 to KH570 is 1:

1. The addition amount of the silane coupling agent is 3% of the total mass of the rubber powder, and the mass ratio of the total mass of the solid SiO2 particles to the total mass of the silane coupling agent is 1:

1.

5. Use of the environmentally friendly tire recycled rubber particles as an asphalt road construction oil formulation according to claim 1, characterized in that: The dosage of the modified recycled rubber particles is 30% of the total mass of the asphalt road - building oil.

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