High performance rubber composite particle modifier and method of making same

Abstract

This invention belongs to the field of asphalt modification technology and discloses a high-performance rubber composite particle modifier and its preparation method. The high-performance rubber composite particle modifier is prepared by extrusion granulation of a novel thermoplastic elastomer, desulfurized rubber powder, and a rubber deodorizer using a multi-stage screw extruder. The novel thermoplastic elastomer is obtained by chemical grafting of a moderately pyrolyzed rubber polymer, the thermoplastic elastomer, and a second free radical scavenger. The desulfurized rubber powder is obtained by high-temperature oxygen-free degradation of a second rubber powder and a third free radical scavenger. Rubber-modified asphalt prepared using the high-performance rubber composite particle modifier of this invention exhibits superior high and low temperature performance, heat and oxygen aging resistance, and storage stability. It also demonstrates good workability, minimal performance degradation during long-term high-temperature storage, significantly reduced odor emissions, and a more stable and lasting odor-neutralizing effect, thus significantly extending the service life of asphalt pavements and improving environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of asphalt modification technology, specifically relating to a high-performance rubber composite particle modifier and its preparation method. Background Technology

[0002] Rubberized asphalt is a modified road asphalt made primarily from waste tire rubber powder and supplemented with other additives through high-temperature processing. It is generally believed that rubber powder plays a dual-modification role in asphalt modification, primarily through physical swelling and dispersion, supplemented by chemical degradation. Although rubberized asphalt is a popular modified asphalt technology, compared to traditional petroleum asphalt and SBS modified asphalt, it has a higher kinematic viscosity, requiring more sophisticated production, mixing, and construction processes. To address this, the industry has adopted measures such as adding appropriate amounts of warm mix additives to the rubberized asphalt system or using desulfurized rubber powder to prepare rubberized asphalt. Due to the poor bonding force between granular rubber powder and asphalt, rubber asphalt exhibits poor overall physical properties and high-temperature storage stability. To address this issue, industry scholars have conducted extensive research, employing methods such as adding appropriate chemical crosslinking agents, increasing aromatic asphalt compatibilizers, and adding elastomeric polymers, such as styrene-butadiene block copolymers (SBS), to improve the overall physical properties and high-temperature storage stability of rubber asphalt. Among these methods, adding SBS is the most common. The underlying principle is that after sufficient swelling, SBS, under the action of chemical crosslinking agents, forms a weak chemical bond with the active components in the rubber powder and asphalt, thus achieving a relatively stable state. However, this relatively stable state is easily destroyed with prolonged storage time and high-temperature thermal oxidation. Furthermore, the mainstream rubber asphalt production process both domestically and internationally is the high-temperature method, which involves adding waste rubber powder to asphalt at a high temperature of 200-230℃ and stirring for a prolonged period (no less than 45 minutes). The production of rubber powder asphalt using this process is energy-intensive. Furthermore, the high temperatures generated by the rubber powder and asphalt produce large amounts of fumes and toxic substances, leading to secondary environmental pollution and the production of malodorous gases, such as hydrogen sulfide. This has immeasurable impacts on the environment and human health. To address the problem of toxic and malodorous gases emitted by rubber asphalt at high temperatures, many scholars have explored methods such as desulfurization pretreatment of rubber powder and the addition of appropriate rubber odor deodorizers during the rubber asphalt production process. Among these methods, rubber odor deodorizers with a dual mechanism of physical adsorption and chemical chelation can improve the odor of rubber asphalt in a short time. However, as processing and storage time increase, the effectiveness of these deodorizers gradually diminishes and may even become ineffective.

[0003] New technologies are urgently needed to address the technical challenges of high-temperature production and storage of rubber asphalt, such as the easy degradation of its comprehensive physical properties, poor long-term thermal storage stability, and the accompanying foul odor. Summary of the Invention

[0004] This invention addresses the shortcomings of the prior art by providing a high-performance rubber composite particle modifier and its preparation method. It improves upon the problems in the prior art where rubber powder composite modified asphalt suffers from performance degradation and decreased storage stability due to heat-oxygen and ultraviolet heat-oxygen / ultraviolet aging during high-temperature long-term storage. At the same time, it significantly reduces the odor and toxic and harmful gas emissions generated during the production and construction of rubber asphalt.

[0005] To achieve the above objectives, the technical solution of this invention is as follows:

[0006] A high-performance rubber composite particle modifier is prepared by extruding and granulating a novel thermoplastic elastomer, desulfurized rubber powder, and rubber deodorizer in a mass ratio of 10-30:30-65:2-7 using a multi-stage screw extruder.

[0007] The novel thermoplastic elastomer is prepared by chemical grafting of a moderately pyrolyzed rubber polymer, a thermoplastic elastomer, and a second free radical scavenger in a mass ratio of 20-60:40-80:0.2-0.6; the moderately pyrolyzed rubber polymer is obtained by high-temperature pyrolysis of a first rubber powder and a first free radical scavenger in a mass ratio of 100:0.15-2.5; and the desulfurized rubber powder is obtained by high-temperature oxygen-free degradation of a second rubber powder and a third free radical scavenger in a mass ratio of 100:0.15-2.5.

[0008] Preferably, the acetone-soluble content of the moderately pyrolyzed rubber polymer is ≤10% by weight, the trichloroethylene-soluble content is ≥90% by weight, the number-average molecular weight (Mn) of the trichloroethylene-soluble content is between 2000-5000 g / mol, and the polydispersity index (PDI) of the polymer is between 3.0-5.5.

[0009] Preferably, the acetone-soluble content of the novel thermoplastic elastomer is ≤10% by weight, the trichloroethylene-soluble content is ≥90% by weight, the number-average molecular weight (Mn) of the trichloroethylene-soluble content is between 100,000 and 550,000 g / mol, and the polydispersity index (PDI) is between 2.0 and 5.0.

[0010] Preferably, the first rubber powder and the second rubber powder are any one or more combinations of waste all-steel radial tires, waste semi-steel radial tires, and waste bicycle tires; wherein the particle size range of the first rubber powder is 20-100 mesh, and the particle size range of the second rubber powder is 60-120 mesh.

[0011] Preferably, the first free radical scavenger, the second free radical scavenger, and the third free radical scavenger are all combinations of one or more of diphenylamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and 2,6-di-tert-butyl-4-methylphenol.

[0012] Preferably, the thermoplastic elasticity is any one or a combination of two of styrene-butadiene-styrene block copolymer and styrene-isoprene-styrene.

[0013] Preferably, the rubber deodorizer is prepared by mixing a chemical deodorizer and a physical deodorizer in a mass ratio of 1:1.

[0014] Preferably, the chemical deodorizer is any one of hydroquinone, salicylic acid, sodium dodecylbenzenesulfonate, and octadecylamine, and the physical deodorizer is any one of activated carbon fiber, alumina, and diatomaceous earth.

[0015] This invention also provides a method for preparing a high-performance rubber composite particle modifier, comprising the following steps:

[0016] S1, the first rubber powder and the first free radical scavenger are put into a high-speed mixer and mixed for 20-40 minutes until the temperature of the mixed rubber powder rises to 115-145℃, to obtain rubber powder mixture A;

[0017] S2, continuously and in a closed manner inject the rubber powder mixture A into the first-stage screw extruder, and control the temperature of the screw extruder temperature zone to be 380-430℃;

[0018] S3, the material obtained from the first-stage screw extruder is continuously and in a sealed manner injected at a constant temperature into the second-stage venting screw extruder. The temperature of the first venting zone of the second-stage venting screw extruder is controlled at 270-310℃ and a vacuum is drawn, with a vacuum degree of 10. -2 -10 -3 pa; The temperature of the second exhaust zone of the second-stage exhaust screw extruder is controlled at 190-230℃ and a vacuum is applied with a vacuum degree of 10. -3 -10 -6 pa;

[0019] S4. Add the thermoplastic elastomer and the second free radical scavenger into a high-speed mixer and mix for 5-10 minutes until the material temperature rises to 60-90℃ to obtain thermoplastic elastomer mixture B.

[0020] S5, the material obtained by the second-stage exhaust screw extruder is continuously and sealedly injected into the first feed port of the third-stage screw extruder at a constant temperature, and the thermoplastic elastomer mixture B is continuously and sealedly injected into the second feed port of the third-stage screw extruder. The temperature of the third-stage extruder is controlled at 190-230℃. The material is melted and mixed and undergoes a chemical reaction to obtain a new thermoplastic elastomer mixture C.

[0021] S6. The second rubber powder and the third free radical scavenger are put into a high-speed mixer under a nitrogen atmosphere and stirred for 20-40 minutes in an oxygen-free environment until the temperature of the mixed rubber powder rises to 145-175℃ to obtain desulfurized rubber powder.

[0022] S7, desulfurized rubber powder is continuously and sealedly injected at a constant temperature through the first feed port of the fourth-stage screw extruder, novel thermoplastic elastomer mixture C is continuously and sealedly injected at a constant temperature through the second feed port of the fourth-stage screw extruder, and rubber deodorizer is continuously and sealedly injected through the third feed port of the fourth-stage screw extruder. The temperature of the fourth-stage extruder is controlled at 190-230℃. The materials are melted, mixed, and chemically reacted, and then extruded and granulated to obtain a high-performance rubber composite particle modifier.

[0023] In the preparation method of the above-mentioned high-performance rubber composite particle modifier, the first-stage screw extruder is a twin-screw extruder or a three-screw extruder with a screw speed of 50-90 rpm; the second-stage screw extruder is a vented twin-screw extruder or a vented three-screw extruder with a screw speed of 40-70 rpm; and the third-stage and fourth-stage screw extruders are twin-screw extruders or three-screw extruders with a screw speed of 60-120 rpm.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] (1) Unlike traditional asphalt modifiers such as styrene-butadiene block copolymer (SBS) / styrene-isoprene-styrene block copolymer (SIS), the polymer molecular chain free radicals formed by the moderate cracking of rubber in this invention achieve molecular-level melt blending and grafting with SBS / SIS under high temperature and oxygen-free conditions to form a novel thermoplastic elastomer. This novel thermoplastic elastomer has stronger resistance to thermo-oxidative / ultraviolet aging, which essentially improves the aging resistance of thermoplastic elastomer modifiers in rubber-modified asphalt and greatly delays the degradation of the comprehensive physical properties of rubber asphalt during high-temperature storage. In addition, the novel thermoplastic elastomer component in the modified composite particles has a significantly higher molecular weight than SBS / SIS. When applied to rubber-modified asphalt, the cohesiveness, adhesion, and viscosity of the asphalt are greatly improved, further enhancing the high and low temperature performance and water damage resistance of rubber-modified asphalt.

[0026] (2) Traditional rubber-modified asphalt uses chemical crosslinking aids to form weak chemical bonds between rubber powder (or desulfurized rubber powder), elastomer polymers (mainly SBS), and asphalt. These chemical bonds are formed by the crosslinking action of sulfur-containing chemical crosslinking aids, which inevitably produces some sulfur-containing gases, such as H2S and other odorous gases. At the same time, these chemical bonds are easily broken by high temperature and oxygen, which greatly affects the stability of the asphalt system, leading to a decline in the overall physical properties of the rubber-modified asphalt and a decrease in high-temperature storage stability. In contrast, during the preparation of the product of this invention, a portion of the novel thermoplastic elastomer and desulfurized rubber powder undergo further graft copolymerization in a high-temperature oxygen-free environment, forming a "hyperbranched" core-shell structure of moderately pyrolyzed rubber polymer-SBS-desulfurized rubber powder. This "hyperbranched" core-shell structure is significantly different from that of traditional rubber-modified asphalt. The structural stability of the moderately pyrolyzed rubber polymer-SBS-desulfurized rubber powder is significantly enhanced, resulting in better aging resistance in the asphalt system and stronger performance stability of the rubber-modified asphalt.

[0027] (3) Traditional rubber powder composite modified asphalt is prepared by blending rubber powder or desulfurized rubber powder and polymer with asphalt. Even when desulfurized rubber powder is used, the high-temperature viscosity of the modified asphalt is still relatively high due to the shallow desulfurization degree of the desulfurized rubber powder prepared by traditional technology, which still has a significant impact on construction and workability. The product of this invention adopts a core-shell structure of moderately cracked rubber polymer-SBS-desulfurized rubber powder, which acts on the modified asphalt. The high-temperature viscosity of the system is lower, and the impact on construction and workability is smaller. It can be used to prepare high-dosage, low-viscosity rubber composite modified asphalt.

[0028] (4) One of the traditional methods for reducing odor emissions in rubber-modified asphalt is to add an appropriate amount of rubber deodorizer along with rubber powder during the production process to reduce the amount of odor emissions during production. This method can effectively reduce the concentration of odorous gases in a localized and short-term manner. However, as time goes on, the excess rubber deodorizer gradually becomes ineffective, its ability to adsorb / chelate odorous gases decreases, and the concentration of odorous gases gradually increases, making it difficult to achieve the goal of "odor removal" in a sustained and long-term manner. The product of this invention achieves molecular-level melt blending of a physical-chemical combination rubber deodorizer and a modifier component of a moderately cracked rubber polymer-SBS-desulfurized rubber powder. The rubber deodorizer is uniformly "pre-embedded" in the product of this invention. During the asphalt modification process, the product of this invention gradually and slowly dissolves in the asphalt under the action of stirring. At the same time, the rubber deodorizer also gradually and slowly dissolves in the asphalt system and adsorbs / chelates odorous gases until the production cycle is completed. The rubber deodorizer achieves a capsule-like "slow release" throughout the process, ensuring stable and low-concentration emissions of odorous gases throughout the cycle, thereby achieving a stable and long-lasting "odor removal" effect. Detailed Implementation

[0029] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following examples provide a detailed description of the specific implementation methods, features, and effects of the present invention.

[0030] The high-performance rubber composite particle modifier and its preparation method described in this invention can be made using the following materials and components, but are not limited to them, such as: waste rubber, SBS, SIS, rubber deodorizer, antioxidant, asphalt, screw extruder, etc.

[0031] Examples 1-7

[0032] A method for preparing a high-performance rubber composite particle modifier includes the following steps:

[0033] S1, 40 mesh waste all-steel radial tire rubber powder and 2,6-di-tert-butyl-4-methylphenol are put into a high-speed mixer and mixed for 20 minutes until the temperature of the mixed rubber powder is 115℃ to obtain mixture A;

[0034] S2: Add mixture A to the first-stage co-rotating parallel twin-screw extruder, and control the temperature of the first-stage extruder to 420℃ and the screw speed to 65rpm;

[0035] S3: The material obtained from the high-temperature pyrolysis of the first-stage screw extruder is continuously injected into the second-stage venting screw extruder in a sealed, oxygen-free environment. The first venting temperature zone of the second-stage venting screw extruder is controlled at 290℃ and a vacuum of 0.006 Pa is applied; the second venting temperature zone of the second-stage venting screw extruder is controlled at 220℃ and a vacuum of 10 Pa is applied. -5 pa, screw speed 50 rpm;

[0036] S4: Add SBS (Sinopec Yueyang Petrochemical model: 791-H: Mn: 98000g / mol, PDI: 3.2, trichloroethylene soluble content: 100%) and 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 7 minutes until the material temperature reaches 80℃ to obtain mixture B;

[0037] S5: The material obtained in S3 and mixture B are continuously injected into the third-stage screw extruder in a closed and oxygen-free environment. The temperature of the third-stage screw extruder is controlled at 220℃ and the screw speed is 85rpm. After the material is melt-mixed and grafted, a mixture of a novel thermoplastic elastomer and a moderately cracked rubber polymer is obtained, namely mixture C.

[0038] S6: Add 80-mesh waste all-steel radial tire rubber powder and 2,6-di-tert-butyl-4-methylphenol to a high-speed mixer under nitrogen atmosphere and stir for 30 minutes in an oxygen-free environment until the temperature of the mixed rubber powder rises to 170℃ to obtain desulfurized rubber powder.

[0039] S7: The desulfurized rubber powder obtained from S6, the mixture C obtained from S5, and the rubber deodorizer are continuously injected into the fourth-stage screw extruder in a closed and oxygen-free environment. The temperature of the fourth-stage extruder is controlled at 220℃ and the screw speed is 85rpm. After the materials are melted, mixed and chemically reacted, they are extruded to obtain a high-performance rubber composite particle modifier. The rubber deodorizer is a mixture of hydroquinone and alumina with a mass ratio of 1:1.

[0040] The differences between Examples 1-7 lie in the different mass proportions of the raw material components, including the first rubber powder (40-mesh waste all-steel radial tire rubber powder), the second rubber powder (80-mesh waste all-steel radial tire rubber powder), thermoplastic elastomer (SBS), the first free radical scavenger (2,6-di-tert-butyl-4-methylphenol), the second free radical scavenger (2,6-di-tert-butyl-4-methylphenol), the third free radical scavenger (2,6-di-tert-butyl-4-methylphenol), and the rubber deodorizer. See Table 1 for details.

[0041] Table 1

[0042]

[0043] Examples 8-10

[0044] This invention discloses a method for preparing a moderately pyrolytic polymer, comprising the following steps:

[0045] S1: Add 100 parts by weight of 40-mesh waste all-steel radial tire rubber powder and 0.15 parts by weight of 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 20 minutes until the temperature of the mixed rubber powder is 115℃ to obtain mixture A;

[0046] S2: Add mixture A to the first-stage co-rotating parallel twin-screw extruder, and control the temperature of the first-stage extruder to 380℃ and the screw speed to 65rpm;

[0047] S3: The material obtained from the high-temperature pyrolysis of the first-stage screw extruder is continuously injected into the second-stage venting screw extruder in a closed and oxygen-free environment. The first venting temperature zone of the venting screw extruder is controlled at 290°C and a vacuum is drawn with a vacuum degree of 0.006 Pa. The second venting temperature zone of the venting screw extruder is controlled at 220°C and a vacuum is drawn with a vacuum degree of 10⁻⁵ Pa. The screw speed is 50 rpm.

[0048] S4: The material obtained in S3 is continuously injected into the third-stage screw extruder in a closed, oxygen-free environment. The temperature of the third-stage screw extruder is controlled at 150℃ and the screw speed is 85rpm.

[0049] S5: The material obtained in S4 is continuously injected into the fourth-stage screw extruder in a closed, oxygen-free environment. The temperature of the fourth-stage extruder is controlled at 50°C and the screw speed is 85 rpm. The material is extruded to obtain a moderately cracked polymer.

[0050] The difference between Examples 8-10 is that the temperature of the first-stage screw extruder in step S2 of each example is different: 380°C in Example 8; 420°C in Example 9; and 430°C in Example 10. Step S5 is a further optimization of step S4, which involves continuing to cool down.

[0051] Examples 11-14

[0052] This invention discloses a method for preparing a novel thermoplastic elastomer, comprising the following steps:

[0053] S1: Add 40-mesh waste all-steel radial tire rubber powder and 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 20 minutes until the temperature of the mixed rubber powder is 115℃ to obtain mixture A;

[0054] S2: Add the mixed rubber powder to the first-stage co-rotating parallel twin-screw extruder, and control the temperature of the first-stage extruder to 420℃ and the screw speed to 65rpm;

[0055] S3: The material obtained from the high-temperature pyrolysis of the first-stage screw extruder is continuously injected into the second-stage venting screw extruder in a closed and oxygen-free environment. The first venting temperature zone of the venting screw extruder is controlled at 290°C and a vacuum is drawn with a vacuum degree of 0.006 Pa. The second venting temperature zone of the venting screw extruder is controlled at 220°C and a vacuum is drawn with a vacuum degree of 10⁻⁵ Pa. The screw speed is 50 rpm.

[0056] S4: Add SBS (Sinopec Yueyang Petrochemical model: 791-H: Mn: 98000g / mol, PDI: 3.2, trichloroethylene soluble content: 100%) and 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 7 minutes until the material temperature reaches 80℃ to obtain mixture B;

[0057] S5: The material obtained in S3 and mixture B are continuously injected into the third-stage screw extruder in a closed and oxygen-free environment. The temperature of the third-stage screw extruder is controlled at 220℃ and the screw speed is 85rpm. After the material is melt-mixed and grafted, a mixture of a novel thermoplastic elastomer and a moderately cracked rubber polymer is obtained, namely mixture C.

[0058] S6: The mixture C obtained from S5 is continuously injected into a closed, oxygen-free fourth-stage screw extruder. The temperature of the fourth-stage extruder is controlled at 220℃ and the screw speed is 85rpm. A novel thermoplastic elastomer is obtained by extrusion.

[0059] The differences between Examples 11-14 lie in the rubber powder, elastomer polymer, first / second free radical scavenger, and their composition ratios, as detailed in Table 2:

[0060] Table 2

[0061]

[0062] Comparative Example D1

[0063] A method for preparing a high-performance rubber composite particle modifier includes the following steps:

[0064] S1: Add 36 parts by weight of 40-mesh waste all-steel radial tire rubber powder and 0.108 parts by weight of 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 20 minutes until the temperature of the mixed rubber powder is 115℃ to obtain mixture A;

[0065] S2: Add mixture A to the first-stage co-rotating parallel twin-screw extruder, and control the temperature of the first-stage extruder to 420℃ and the screw speed to 65rpm;

[0066] S3: The material obtained from the high-temperature pyrolysis of the first-stage screw extruder is continuously injected into the second-stage venting screw extruder in a sealed, oxygen-free environment. The first venting temperature zone of the venting screw extruder is controlled at 290℃ and a vacuum of 0.006 Pa is applied; the second venting temperature zone of the venting screw extruder is controlled at 220℃ and a vacuum of 10 Pa is applied. -5 pa, screw speed 50 rpm;

[0067] S4: Add 14 parts by mass of SBS (Sinopec Yueyang Petrochemical model: 791-H: Mn: 98000g / mol, PDI: 3.2, trichloroethylene soluble content: 100%) and 0.065 parts by mass of 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 7 minutes until the material temperature reaches 80℃ to obtain mixture B;

[0068] S5: The material obtained after vacuum separation of the second-stage screw and mixture B are continuously injected into the third-stage screw extruder in a sealed and oxygen-free manner according to the mass ratio of 36.108:14.065. The temperature of the third-stage extruder is controlled at 150℃ and the screw speed is 85rpm. After the material is melt-mixed and grafted, a mixture of a new thermoplastic elastomer and a moderately cracked rubber polymer is obtained, namely mixture C.

[0069] S6: Add 50 parts by weight of 80-mesh waste all-steel radial tire rubber powder and 0.1 parts by weight of 2,6-di-tert-butyl-4-methylphenol to a high-speed mixer under nitrogen atmosphere and stir for 30 minutes in an oxygen-free environment until the temperature of the mixed rubber powder rises to 170℃ to obtain desulfurized rubber powder.

[0070] S7: The desulfurized rubber powder obtained from S6, the novel thermoplastic elastomer obtained from S5, the mixture of moderately cracked rubber polymer, and the rubber deodorizer (a mixture of hydroquinone and alumina in a mass ratio of 1:1) are continuously injected into the fourth-stage screw extruder in a closed, oxygen-free manner according to a mass fraction ratio of 50.1:50.137:4. The temperature of the fourth-stage extruder is controlled at 140℃ and the screw speed is 85rpm. After the materials are melted, mixed, and chemically reacted, they are extruded to obtain a high-performance rubber composite particle modifier.

[0071] Comparative Example D2

[0072] A method for preparing a high-performance rubber composite particle modifier includes the following steps:

[0073] S1: Add 36 parts by weight of 40-mesh waste all-steel radial tire rubber powder and 0.108 parts by weight of 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 20 minutes until the temperature of the mixed rubber powder is 115℃ to obtain mixture A;

[0074] S2: Add mixture A to the first-stage co-rotating parallel twin-screw extruder, and control the temperature of the first-stage extruder to 420℃ and the screw speed to 65rpm;

[0075] S3: The material obtained from the high-temperature pyrolysis of the first-stage screw extruder is continuously injected into the second-stage venting screw extruder in a sealed, oxygen-free environment. The first venting temperature zone of the venting screw extruder is controlled at 290℃ and a vacuum of 0.006 Pa is applied; the second venting temperature zone of the venting screw extruder is controlled at 220℃ and a vacuum of 10 Pa is applied. -5 pa, screw speed 50 rpm;

[0076] S4: Add 14 parts by mass of SBS (Sinopec Yueyang Petrochemical model: 791-H: Mn: 98000g / mol, PDI: 3.2, trichloroethylene soluble content: 100%) and 0.065 parts by mass of 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 7 minutes until the material temperature reaches 80℃ to obtain mixture B;

[0077] S5: The material obtained after vacuum separation of the second-stage screw and mixture B are continuously injected into the third-stage screw extruder in a closed and oxygen-free manner according to the mass ratio of 36.108:14.065. The temperature of the third-stage extruder is controlled at 220℃ and the screw speed is 85rpm. After the material is melt-mixed and grafted, a mixture of a new thermoplastic elastomer and a moderately cracked rubber polymer is obtained, namely mixture C.

[0078] S6: Add 50 parts by weight of 80-mesh waste all-steel radial tire rubber powder and 0.1 parts by weight of 2,6-di-tert-butyl-4-methylphenol to a high-speed mixer under nitrogen atmosphere and stir for 30 minutes in an oxygen-free environment until the temperature of the mixed rubber powder rises to 170℃ to obtain desulfurized rubber powder.

[0079] S7: The mixture of desulfurized rubber powder obtained from S6, novel thermoplastic elastomer obtained from S5, and moderately cracked rubber polymer is continuously injected into a fourth-stage screw extruder in a closed, oxygen-free environment at a mass fraction ratio of 50.1:50.137. The temperature of the fourth-stage extruder is controlled at 220℃ and the screw speed is 85rpm. After the materials are melted, mixed, and chemically reacted, they are extruded to obtain a high-performance rubber composite particle modifier.

[0080] Comparative Example D3

[0081] A method for preparing a high-performance rubber composite particle modifier includes the following steps:

[0082] S1: Add 36 parts by weight of 40-mesh waste all-steel radial tire rubber powder and 0.108 parts by weight of 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 20 minutes until the temperature of the mixed rubber powder is 115℃ to obtain mixture A;

[0083] S2: Add mixture A to the first-stage co-rotating parallel twin-screw extruder, and control the temperature of the first-stage extruder to 420℃ and the screw speed to 65rpm;

[0084] S3: The material obtained from the high-temperature pyrolysis of the first-stage screw extruder is continuously injected into the second-stage venting screw extruder in a sealed, oxygen-free environment. The first venting temperature zone of the venting screw extruder is controlled at 290℃ and a vacuum of 0.006 Pa is applied; the second venting temperature zone of the venting screw extruder is controlled at 220℃ and a vacuum of 10 Pa is applied. -5 pa, screw speed 50 rpm;

[0085] S4: Add 14 parts by mass of SBS (Sinopec Yueyang Petrochemical model: 791-H: Mn: 98000g / mol, PDI: 3.2, trichloroethylene soluble content: 100%) and 0.065 parts by mass of 2,6-di-tert-butyl-4-methylphenol into a high-speed mixer and mix for 7 minutes until the material temperature reaches 80℃ to obtain mixture B;

[0086] S5: The material obtained after vacuum separation of the second-stage screw and mixture B are continuously injected into the third-stage screw extruder in a sealed and oxygen-free manner according to the mass ratio of 36.108:14.065. The temperature of the third-stage extruder is controlled at 150℃ and the screw speed is 85rpm. After the material is melt-mixed and grafted, a mixture of a new thermoplastic elastomer and a moderately cracked rubber polymer is obtained, namely mixture C.

[0087] S6: Add 50 parts by weight of 80-mesh waste all-steel radial tire rubber powder and 0.1 parts by weight of 2,6-di-tert-butyl-4-methylphenol to a high-speed mixer under nitrogen atmosphere and stir for 10 minutes in an oxygen-free environment until the temperature of the mixed rubber powder rises to 75°C to obtain desulfurized rubber powder.

[0088] S7: The desulfurized rubber powder obtained from S6, the novel thermoplastic elastomer obtained from S5, the mixture of moderately cracked rubber polymer, and the rubber deodorizer (a mixture of hydroquinone and alumina in a mass ratio of 1:1) are continuously injected into the fourth-stage screw extruder in a closed, oxygen-free manner according to a mass fraction ratio of 50.1:50.137:4. The temperature of the fourth-stage extruder is controlled at 220℃ and the screw speed is 85rpm. After the materials are melted, mixed, and chemically reacted, they are extruded to obtain a high-performance rubber composite particle modifier.

[0089] The products of Examples 8-10 were treated as follows:

[0090] First, acetone was used as the solvent, and Soxhlet extraction was performed continuously for 48 hours until the small organic molecules (acetone-soluble substances) were completely extracted and separated by acetone. Subsequently, the soluble fraction was dried in a vacuum drying oven until its mass remained constant; the insoluble fraction was dried until its mass remained constant, and a second extraction was performed using trichloroethylene as the solvent to separate the large molecular soluble substances (trichloroethylene-soluble substances) and the insoluble substances.

[0091] The number average molecular weight and polydispersity index (PDI) of trichloroethylene solubles were tested (GPC testing can simultaneously characterize molecular weight and PDI). The test method is as follows: the trichloroethylene solubles were fully swollen with toluene, and then the number average molecular weight (Mn) and polydispersity index (PDI) of each component of the sample were determined using a Waters 515-2410 GPC analyzer. The weight percentage of different molecular weight components was calculated by peak area. Tetrahydrofuran was used as the mobile phase, polystyrene was used as the standard, and the test temperature was 35℃. See Table 3 for details.

[0092] Table 3

[0093]

[0094] The products of Examples 11-14 were treated as follows:

[0095] First, acetone was used as the solvent, and Soxhlet extraction was performed continuously for 48 hours until the small organic molecules (acetone-soluble substances) were completely extracted and separated by acetone. Subsequently, the soluble fraction was dried in a vacuum drying oven until its mass remained constant; the insoluble fraction was dried until its mass remained constant, and a second extraction was performed using trichloroethylene as the solvent to separate the large molecular soluble substances (trichloroethylene-soluble substances) and the insoluble substances.

[0096] The number average molecular weight and polydispersity index (PDI) of trichloroethylene solubles were tested (GPC testing can simultaneously characterize molecular weight and PDI). The test method is as follows: the trichloroethylene solubles were fully swollen with toluene, and then the number average molecular weight (Mn) and polydispersity index (PDI) of each component of the sample were determined using a Waters 515-2410 GPC analyzer. The weight percentage of different molecular weight components was calculated by peak area. Tetrahydrofuran was used as the mobile phase, polystyrene was used as the standard, and the test temperature was 35℃. See Table 4 for details.

[0097] Table 4

[0098]

[0099] The products of Examples 1-7 and Comparative Examples 1-3 were subjected to the following treatment:

[0100] (1) Using trichloroethylene as a solvent, Soxhlet extraction was performed continuously for 48 hours until the organic soluble matter was completely extracted and separated. Subsequently, the soluble part was dried in a vacuum drying oven until its mass remained unchanged, and the insoluble part was dried until its mass remained unchanged.

[0101] (2) The average molecular weight and polydispersity index (PDI) of trichloroethylene solubles were tested (GPC test can characterize molecular weight and polydispersity index (PDI) simultaneously). The test method is as follows: trichloroethylene solubles were fully swollen with toluene, and then the number average molecular weight (Mn) and polydispersity index (PDI) of each component of the sample were determined using a Waters 515-2410 GPC analyzer. The weight percentage of different molecular weight components was calculated by peak area. Tetrahydrofuran was used as the mobile phase and polystyrene was used as the standard. The test temperature was 35℃.

[0102] (3) The insoluble trichloroethylene was inserted into a cylindrical glass tube, and the crosslinking density of the sample was determined using an MR-CDS 3500 NMR crosslinking density meter manufactured by Innovative Imaging GmbH, Germany, at a magnetic induction intensity of 3.5 A / m, a frequency of 15 MHz, and a temperature of 60°C. See Table 5 for details.

[0103] Table 5

[0104]

[0105]

[0106] It is important to clarify that, based on the principle of "like dissolves like" in organic molecules, trichloroethylene can effectively dissolve organic polymers. In the absence of cross-linking between molecular chain segments, both lower and higher molecular weight organic polymers can be well dissolved. Acetone, as another solvent for organic molecules, exhibits good solubility for small molecular weight polymers but poor solubility for larger molecular weight organic polymers. Academically, these two types of solvents are commonly used to separate small and large organic polymers. According to the relevant data from Examples 1-7 and Comparative Examples D1-D3 in Table 5, the component contents of the moderately pyrolyzed rubber polymer, SBS, and desulfurized rubber powder in the product changed significantly compared to the raw material ratio. The molecular weight of the trichloroethylene-soluble components was higher than that of SBS and the moderately pyrolyzed rubber polymer, while the cross-linking density of the trichloroethylene-insoluble components was slightly higher than that of the desulfurized rubber powder. These phenomena indicate that, under certain process conditions, the moderately pyrolyzed polymer, SBS, and desulfurized rubber powder underwent a free radical copolymerization reaction, resulting in the presence of SBS-moderately pyrolyzed rubber polymer copolymers and SBS-moderately pyrolyzed rubber polymer copolymer-desulfurized rubber powder copolymers in the product.

[0107] To illustrate the beneficial effects of the high-performance rubber composite particle modifier prepared by the present invention in the application of rubber composite modified asphalt, the following exemplary comparison of the performance of modified asphalt prepared using the high-performance rubber composite particles of the present invention as modifier and traditional rubber composite modified asphalt is provided.

[0108] Examples 15-21, Comparative Examples DM1-DM4

[0109] The specific asphalt modification process is as follows: Qinhuangdao 70A base asphalt (from PetroChina Qinhuangdao Refinery, whose physical properties meet the technical requirements for base asphalt in JTG F40-2004) is heated to 190℃, and high-performance rubber composite particle modifier or 40-mesh rubber, SBS (791-H) and rubber deodorizer (a mixture of hydroquinone and alumina in a mass ratio of 1:1) are added. The mixture is kept at this temperature and stirred for 45 minutes at a stirring speed of 1000 rpm. Then, the stirring speed is increased to 5000 rpm, a stabilizer is added, and the mixture is kept at this temperature and stirred for 240 / 480 / 720 minutes. After the process, the performance indicators of each modified asphalt and the changes in VOC emission content are tested.

[0110] The amounts of each raw material added in Examples 15 to 21 and Comparative Examples DM1 to DM4 are shown in Table 6. The performance indicators of the modified asphalt in each example and comparative example are shown in Table 7. The VOC emissions of the modified asphalt in each example and comparative example are shown in Table 8.

[0111] Table 6

[0112]

[0113] Table 7

[0114]

[0115]

[0116] Note: The testing methods shall be in accordance with the relevant testing methods in JTG E20-2011 standard.

[0117] Table 8

[0118]

[0119]

[0120] The results of the rubber-modified asphalt in the above examples show that:

[0121] (1) As can be seen from Examples 15-21 and Comparative Example DM1, compared with traditional rubber powder composite modified asphalt, the rubber composite modified asphalt of the present invention has significantly better high-temperature (softening point) and low-temperature (5°C ductility) performance, significantly lower high-temperature rotational viscosity, stronger heat-oxidative aging resistance (RTOFT), and better high-temperature long-term storage stability. The long-term high-temperature stirring and development process has less impact on the high and low temperature, heat-oxidative aging resistance, and high-temperature long-term storage stability of the composite modified asphalt of the present invention. This indicates that the high-performance rubber composite particle modifier of the present invention has better comprehensive physical properties than traditional technology, especially excellent aging resistance, and better compatibility with asphalt.

[0122] As can be seen from Examples 15-21 and Comparative Example DM1, compared with traditional rubber powder composite modified asphalt, the odorous gas emission of the modified asphalt of the present invention is significantly lower than that of traditional technical methods. Moreover, with the development of high temperature and long-term stirring, the odorous gas emission remains at an extremely low level. This indicates that the ability of the high-performance rubber composite particle modifier of the present invention to generate toxic and harmful gases is greatly reduced after desulfurization and degradation treatment. It also indicates that the rubber deodorizer is pre-embedded in the rubber asphalt composite particles and enters the asphalt system through capsule-type slow release, which can stably capture and absorb toxic and harmful gases, so that the generation and emission of odorous gases from rubber asphalt are maintained at an extremely low level.

[0123] (2) As can be seen from Examples 15-21 and Comparative Example DM2, the moderately cracked rubber polymer, styrene-butadiene block copolymer (SBS), and desulfurized rubber powder components in the high-performance rubber composite particle modifier of the present invention are chemically copolymerized, resulting in superior low-temperature performance and heat-oxidative aging resistance (RTOFT) of the granular composite modified asphalt, as well as superior high-temperature long-term storage stability. The long-term high-temperature stirring and development process has less impact on the high and low temperature, heat-oxidative aging resistance, and high-temperature long-term storage stability of the composite modified asphalt of the present invention. This indicates that the high-performance rubber asphalt composite particles of the present invention underwent a copolymerization reaction during the preparation process, forming a new product: SBS-moderately cracked rubber polymer-desulfurized rubber powder. This product has a larger molecular weight, stronger aging resistance, and a more significant comprehensive contribution to the modified asphalt.

[0124] (3) As can be seen from Examples 15-21 and Comparative Example DM3, when the rubber deodorizer is uniformly embedded in the high-performance rubber composite particle modifier of the present invention, the rubber composite modified asphalt has a longer-lasting ability to absorb / adsorb malodorous gases during preparation and long-term high-temperature storage, and the deodorization effect is more stable and lasting.

[0125] (4) As can be seen from Examples 15-21 and Comparative Example DM4, the desulfurized rubber powder component in the high-performance rubber composite particle modifier was not pre-desulfurized. The high temperature (softening point), low temperature (5℃ ductility), high temperature rotational viscosity, heat and oxygen aging resistance (RTOFT) and high temperature long-term storage stability of the particle composite modified asphalt were weaker. The high and low temperature, heat and oxygen aging resistance, and high temperature long-term storage stability of the composite modified asphalt were more significantly affected by the long-term high temperature stirring development process, and the odor gas emission was higher.

[0126] The sequence numbers of the above embodiments of the present invention are merely for description and do not represent the superiority or inferiority of the embodiments. Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of some modifications and the superposition of necessary general technologies; of course, they can also be implemented by simplifying some important technical features.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-performance rubber composite particle modifier, characterized in that: It is prepared by extruding and granulating a novel thermoplastic elastomer, desulfurized rubber powder and rubber deodorizer in a mass ratio of 10-30:30-65:2-7 using a multi-stage screw extruder. The novel thermoplastic elastomer is prepared by chemical grafting of a moderately pyrolyzed rubber polymer, a thermoplastic elastomer, and a second free radical scavenger in a mass ratio of 20-60:40-80:0.2-0.6; wherein the moderately pyrolyzed rubber polymer is obtained by high-temperature pyrolysis of a first rubber powder and a first free radical scavenger in a mass ratio of 100:0.15-2.

5. The desulfurized rubber powder is prepared by high-temperature oxygen-free degradation of a second rubber powder and a third free radical scavenger in a mass ratio of 100:0.15-2.

5.

2. The high-performance rubber composite particle modifier according to claim 1, characterized in that: The moderately pyrolyzed polymer of the rubber has an acetone-soluble content of ≤10% by weight, a trichloroethylene-soluble content of ≥90% by weight, a number-average molecular weight (Mn) of the trichloroethylene-soluble content between 2000-5000 g / mol, and a polymer polydispersity index (PDI) between 3.0-5.

5.

3. The high-performance rubber composite particle modifier according to claim 1, characterized in that: The novel thermoplastic elastomer has an acetone-soluble content of ≤10% by weight, a trichloroethylene-soluble content of ≥90% by weight, a number-average molecular weight (Mn) of the trichloroethylene-soluble content between 100,000 and 550,000 g / mol, and a polymer polydispersity index (PDI) between 2.0 and 5.

0.

4. The high-performance rubber composite particle modifier according to claim 1, characterized in that: The first rubber powder and the second rubber powder are any one or more combinations of waste all-steel radial tires, waste semi-steel radial tires, and waste bicycle tires; wherein the particle size range of the first rubber powder is 20-100 mesh, and the particle size range of the second rubber powder is 60-120 mesh.

5. The high-performance rubber composite particle modifier according to claim 1, characterized in that: The first free radical scavenger, the second free radical scavenger, and the third free radical scavenger are all combinations of one or more of diphenylamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, and 2,6-di-tert-butyl-4-methylphenol.

6. The high-performance rubber composite particle modifier according to claim 1, characterized in that: The thermoplastic elasticity is any one or a combination of two of styrene-butadiene-styrene block copolymer and styrene-isoprene-styrene.

7. The high-performance rubber composite particle modifier according to claim 1, characterized in that: The rubber deodorizer is prepared by mixing a chemical deodorizer and a physical deodorizer in a mass ratio of 1:

1.

8. The high-performance rubber composite particle modifier according to claim 7, characterized in that: The chemical deodorizer is any one of hydroquinone, salicylic acid, sodium dodecylbenzenesulfonate, and octadecylamine, and the physical deodorizer is any one of activated carbon fiber, alumina, and diatomaceous earth.

9. A method for preparing a high-performance rubber composite particle modifier as described in any one of claims 1-8, characterized in that, Includes the following steps: S1, the first rubber powder and the first free radical scavenger are put into a high-speed mixer and mixed for 20-40 minutes until the temperature of the mixed rubber powder rises to 115-145℃ to obtain mixture A; S2, continuously and in a closed manner inject mixture A into the first-stage screw extruder, and control the temperature of the screw extruder temperature zone to be 380-430℃; S3, the material obtained from the first-stage screw extruder is continuously and in a sealed manner injected at a constant temperature into the second-stage venting screw extruder. The temperature of the first venting zone of the second-stage venting screw extruder is controlled at 270-310℃ and a vacuum is drawn, with a vacuum degree of 10. -2 -10 - 3 pa; The temperature of the second exhaust zone of the second-stage exhaust screw extruder is controlled at 190-230℃ and a vacuum is applied with a vacuum degree of 10. -3 -10 -6 pa; S4. Add the thermoplastic elastomer and the second free radical scavenger into a high-speed mixer and mix for 5-10 minutes until the material temperature rises to 60-90℃ to obtain mixture B. S5, the material obtained by the second-stage exhaust screw extruder is continuously and sealedly injected into the first feed port of the third-stage screw extruder at a constant temperature, and mixture B is continuously and sealedly injected into the second feed port of the third-stage screw extruder. The temperature of the third-stage screw extruder is controlled at 190-230℃. The material is melted and mixed and undergoes a chemical reaction to obtain mixture C. S6. The second rubber powder and the third free radical scavenger are put into a high-speed mixer under a nitrogen atmosphere and stirred for 20-40 minutes in an oxygen-free environment until the temperature of the mixed rubber powder rises to 145-175℃ to obtain desulfurized rubber powder. S7, desulfurized rubber powder is continuously and sealedly injected at a constant temperature through the first feed port of the fourth-stage screw extruder, mixture C is continuously and sealedly injected at a constant temperature through the second feed port of the fourth-stage screw extruder, and rubber deodorizer is continuously and sealedly injected through the third feed port of the fourth-stage screw extruder. The temperature of the fourth-stage extruder is controlled at 190-230℃. The materials are melted, mixed and chemically reacted, and then extruded and granulated to obtain a high-performance rubber composite particle modifier.

10. The method for preparing a high-performance rubber composite particle modifier according to claim 9, characterized in that: The first-stage screw extruder is a twin-screw extruder or a three-screw extruder, with a screw speed of 50-90 rpm; the second-stage vented screw extruder is a vented twin-screw extruder or a vented three-screw extruder, with a screw speed of 40-70 rpm; the third-stage screw extruder and the fourth-stage screw extruder are twin-screw extruders or three-screw extruders, with a screw speed of 60-120 rpm.

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