Process for preparing asphalt modifier through co-pyrolysis activation of waste rubber powder and lignin

Abstract

The invention relates to a process for preparing an asphalt modifier through co-pyrolysis activation of waste rubber powder and lignin. The process utilizes a device consisting of a double-screw extruder, a single-screw extruder and the like, and comprises the following steps: putting low-mesh waste rubber powder, lignin, an activating agent, a softening agent and a stabilizing agent into a stirring tank for premixing treatment, and adding into a co-rotating parallel double-screw extruder and the single-screw extruder through a main feeding port for desulfurization, activation and extrusion, cooling and granulating to obtain a lignin waste rubber powder activated material, and adding the obtained lignin waste rubber powder composite activated material, non-activated high-mesh waste rubber powder, inorganic filler and an SBS modifier into an internal mixer and a granulator for compounding and granulating to obtain the lignin waste rubber powder composite activated material. The prepared composite activation material is environmentally friendly, simple and convenient composite activation of the lignin and the rubber powder is achieved, the storage performance is good, processing is facilitated, the temperature sensitivity of the product is high, and the high-temperature rut resistance, the elastic recovery capacity and the segregation performance of the product are all improved.

Description

Technical Field

[0001] The present invention relates to a process for co - pyrolysis activation of waste rubber powder and lignin for use as an asphalt modifier. A method for preparing a high - performance asphalt modifier from waste resources (waste rubber powder and lignin) through a co - pyrolysis activation process and its application in asphalt pavement materials. This process uses a device composed of a twin - screw extruder and a single - screw extruder, etc., which can co - pyrolyze and activate the rubber powder and lignin, achieving a good composite modification effect, and making the obtained product have strong temperature sensitivity, and improving its high - temperature rutting resistance, elastic recovery ability, and segregation performance. Background Art

[0002] China is a large agricultural country, with an annual output of straw exceeding 900 million tons. Lignin widely exists in the cell walls of plants such as straw and is the most abundant renewable and natural aromatic compound on earth. Most lignin is a by - product in the pulp and paper - making process and is usually recycled as boiler fuel in pulp and paper mills, with only about 5% used for other purposes, which causes serious waste of resources and environmental pollution. As the main component of papermaking waste, lignin has a high carbon content and thermal stability, but it is difficult to effectively combine with asphalt alone.

[0003] Automobile waste tires are also increasing day by day. For a long time, waste tires have been commonly known as "black pollution", so the recycling and treatment of waste tires have become a common worldwide problem. The rubber powder produced by pyrolysis of waste tires can be directly used for asphalt modification, but there are problems such as poor dispersibility and insufficient compatibility with asphalt.

[0004] However, there are many current technologies for applying lignin to rubber, mainly as a reinforcing agent or coupling agent, and there are problems such as low doping ratio and low activation degree. Some studies directly modify lignin with asphalt, but it affects the low - temperature performance of asphalt, so it can only be used when low - temperature ductility is not required. Lignin is mostly used as a fiber - type additive in asphalt mixtures.

[0005] However, there is little research on jointly modifying a large amount of straw - based lignin raw materials and waste tire rubber powder to prepare a composite activated material and applying it to asphalt in road materials. This is of great significance for solving the problem of lignin waste, the "black pollution" problem of waste tires, and promoting green and low - carbon road materials.

[0006] Chinese Patent CN 201310388313.4 discloses an "asphalt modifier with low-temperature resistance and modified asphalt", which is characterized by adding a bio-based filler such as lignin to an asphalt modifier with low-temperature resistance and modified asphalt. However, in the asphalt modifier prepared by this method, a large amount of polyethylene, i.e., PE, is used. PE is also a petroleum derivative and a non-renewable energy source, and its price is relatively high. In addition, the amount of bio-based filler is small, and the dosage of the modifier in asphalt is also small. Therefore, although bio-based fillers are used in this application, the effect on low-carbon is not ideal.

[0007] CN 200910053344.8 discloses an "apparatus for producing a high-viscosity asphalt modifier". The apparatus consists of an automatic batching system, a twin-screw extruder, a single-screw extruder, a pelletizing vehicle, a cooling water tank, a centrifugal dehydrator, a vibrating screen, a blower, a venturi tube, a cyclone drying tank, a circulating water pump, a circulating water tank, etc. However, in this process method, complicated production equipment and processes are used, and high-pressure water washing is not suitable for bio-based materials such as lignin. Therefore, although this technology uses a coherent production apparatus, it is not suitable for bio-based low-carbon road asphalt modifiers.

[0008] CN201810907069.0 discloses a "modified asphalt modifier and its production method", in which a large amount of SBS asphalt modifier is used to obtain better modified asphalt performance. However, this technology is aimed at SBS, a common asphalt modifier. The amount of lignin added is small, and SBS is derived from petroleum, which is a non-renewable resource, and its price is too high. In addition, most of the SBS in China depends on imports, which is not the best choice for the current demand of low-carbon roads.

[0009] In the prior art, the processes of modifying asphalt with waste rubber powder or lignin alone have defects such as limited modification effect, high energy consumption, and insufficient environmental protection. Therefore, there is an urgent need to develop a new type of composite modifier with low cost, greenness, and high efficiency. Summary of the Invention

[0010] The object of the present invention is to provide a process for co-pyrolysis activation of waste rubber powder and lignin for asphalt modifier in view of the problems existing in the prior art, such as low activation degree of the composite material of lignin directly and rubber powder, and low content ratio of lignin. That is, the present invention provides a method for preparing a composite modifier by a co-pyrolysis activation process using waste rubber powder and lignin as raw materials. The composite modifier solves the defects of separately modifying asphalt by the two, and improves the high and low temperature performance, anti-aging property and environmental protection benefit of asphalt. In particular, the present invention uses a device combination process composed of a twin-screw extruder and a single-screw extruder, etc., which can co-pyrolyze and activate the rubber powder and lignin, achieving a good composite modification effect, and the obtained product has strong temperature sensitivity, and its high temperature rutting resistance, elastic recovery ability and segregation performance are all improved.

[0011] The process for co-pyrolysis activation of waste rubber powder and lignin for asphalt modifier provided by the present invention includes the following steps: 1) The process device mainly includes a stirring tank, a co-rotating parallel twin-screw extruder, a single-screw extruder, a mixer, and a granulator; 2) Materials including main components such as waste rubber powder (low mesh number), lignin, activator, softening agent, stabilizer, etc. are first stirred and mixed evenly in the stirring tank (1). After premixing, the materials enter the feeding port (4) through the automatic feeding guide rail (3) of the co-rotating parallel twin-screw extruder and then enter the co-rotating parallel twin-screw extruder; 3) The premixed materials are subjected to high-temperature shearing and desulfurization in the co-rotating parallel twin-screw extruder; the independent control console (2) of the co-rotating parallel twin-screw extruder controls the temperature and rotation speed of each temperature zone, and the temperature is cooled by its cooling water circulation tank (5); 4) After high-temperature shearing and desulfurization, the materials pass through the extrusion port of the co-rotating parallel twin-screw extruder to the connection port (6) of the single-screw extruder, and then are further cooled and formed by the single-screw extruder. Under the combined action of the screw, the engaging block and high temperature, plasticization and modification are carried out to obtain a lignin waste rubber powder composite activated material; 5) Unactivated waste rubber powder (high mesh number), inorganic filler, and SBS modifier (styrene-butadiene-styrene block copolymer) are added to the feeding port (8) of the mixer containing the lignin and waste rubber powder composite activated material. After the upper cover (9) of the mixer controls the lid to be closed and mixed evenly, it is fed through the feeding port (10) of the granulator, cut by the blade cutting system (11) of the granulator, transported by the conveying track (12), cooled by the air blowing system (13), and discharged from the receiving port (14) into finished products and packaging bags to obtain a composite modifier.

[0012] The stirring speed of the said stirring tank is 500 - 2000 rpm, preferably 600 - 650 rpm, the time of premixing treatment is 5 - 30 minutes, preferably 5 - 8 min, and the temperature of premixing treatment is 40 - 100 °C, preferably 45 - 60 °C; The mesh number of the unactivated high-mesh waste rubber powder is 50 - 100 meshes, preferably 60 meshes; the mesh number of the low-mesh waste rubber powder is 5 - 20 meshes, preferably 20 meshes; During the activation extrusion process of the parallel twin-screw extruder, the temperature of each barrel is 210 - 300 °C, preferably 210 - 230 °C, the screw diameter is 25 - 70 mm, preferably 30 - 45 mm, the twin-screw has 8 temperature zones, the screw speed is 550 - 650 rpm, preferably 550 - 600 rpm, and the speed of the single-screw extruder is 50 - 350 rpm, preferably 100 - 150 rpm; The temperature of the internal mixer is 50 - 200 °C, preferably 60 - 90 °C, and the rotational speed of the rotating knife of the granulator is 50 - 150 rpm; preferably 50 - 100 rpm; The lignin is one or two of hydrolyzed lignin, enzymatically hydrolyzed lignin, and alkali lignin, preferably a by-product of corn stover biorefining; The high-mesh waste rubber powder is one or several of the rubber powders prepared by crushing radial tires, non-radial tires, waste conveyor belts, and waste rubber shoes; The mass ratio of the waste rubber powder (low-mesh), lignin, activator, softener, and stabilizer is: 100:45 - 155:1:4:0.5; among them, the waste rubber powder is 100 g as the formula reference amount, and other components are added according to the ratio; The mass ratio of the lignin rubber powder composite activation material, unactivated waste rubber powder (high-mesh), inorganic filler, and SBS modifier (styrene-butadiene-styrene block copolymer) is: 100:20:20:3; The inorganic filler is one or several of montmorillonite, diatomite, hydrotalcite, clay, and light calcium carbonate; The SBS modifier (styrene-butadiene-styrene block copolymer) is star-shaped SBS or linear SBS; The activator is one or several of phenyl disulfide, benzenethiol, polyalkylphenol disulfide, and octadecylamine, preferably phenyl disulfide (B480); The softener is one or several of aromatic oil, naphthenic oil, tall oil pitch, and rosin; The stabilizer is one or several of sulfur powder, dicumyl peroxide, di-tert-butylbenzene peroxide, accelerator TMTD, accelerator M, accelerator DM, zinc stearate, and maleimide.

[0013] The device provided by the present invention mainly includes a stirring tank, a co-rotating parallel twin-screw extruder, a single-screw extruder, a mixer, and a granulator, which are connected in sequence; the material is stirred in the stirring tank, and the co-rotating parallel twin-screw extruder is provided with an independent control console (2) to control the temperature and rotation speed of each temperature zone of the screw; the automatic feeding guide rail (3) is connected to the feeding port (4) of the co-rotating parallel twin-screw extruder, the water-cooled circulating water tank system (5) is connected to the connection port (6) between the twin-screw extruder and the single-screw extruder, the material is extruded from the discharge port (7) of the single-screw extruder, the mixer is provided with a feeding port (8), the upper cover (9) of the mixer is controlled to close the cover by its control console and lifting system, the granulator is provided with a feeding port (10) for feeding, the blade cutting system (11) in the granulator is connected to the conveying track (12), and the air blowing system (13) is connected to the receiving port (14).

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention is a method for preparing a high-performance asphalt modifier by co-pyrolysis activation process using waste resources (waste rubber powder and lignin) and its application in asphalt pavement materials. The present invention realizes a significant increase in the lignin content of the lignin waste rubber powder composite activated material, which can be between 30% and 60%. It is a low-carbon road modifier and a green process. Using waste as raw materials, the carbon resource is realized during the pyrolysis process, reducing environmental pollution.

[0015] 2. The present invention uses a twin-screw extruder and a single-screw extruder to co-pyrolyze and activate the rubber powder and lignin, achieving a good composite modification effect and a synergistic effect: the waste rubber powder provides elasticity, the pyrolytic carbon of lignin enhances rigidity, and the porous structure formed by co-pyrolysis improves the adsorption and stability of asphalt.

[0016] 3. The temperature sensitivity of the product is improved, and its high-temperature rutting resistance, elastic recovery ability, and segregation performance are all improved. The performance is optimized, making the softening point of the modified asphalt increase by 1-13°C, the ductility (5°C) increase by 1-6 cm, the penetration (25°C) increase by 0.5-2 mm, the dynamic viscosity of the modified asphalt (180°C) decrease by 30-50%, and the 24-hour segregation performance is greatly improved.

[0017] In summary, the present invention is a method for co-pyrolysis activation of waste rubber powder and lignin to prepare an asphalt modifier. By co-pyrolysis, a porous composite carbon material is formed, significantly improving the high and low temperature performance, anti-aging property, and durability of asphalt. At the same time, the high-value utilization of waste resources is realized, with significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Shown are the infrared spectra of six different modified asphalts, including the infrared spectrum of the matrix asphalt and the spectra of the modified asphalts in the comparative examples and the examples.

[0019] Figure 2 Scanning microscope image of the base asphalt; Figure 3 Scanning microscope image of the modified asphalt in Comparative Example 2; Figure 4 Scanning microscope image of the modified asphalt in Example 2; Figure 5 Scanning microscope image of the modified asphalt in Example 4.

[0020] Figure 6 Performance graph of the rutting factor for the base asphalt, comparative examples, and examples.

[0021] Figure 7 Schematic diagram of the device used in this process, showing the connection methods of equipment such as the mixing tank, twin-screw extruder, and single-screw extruder.

[0022] The following further elaborates on the present invention in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0023] For the experimental methods and tests without specifying specific conditions in the examples, they are generally carried out according to conventional conditions and the conditions described in the manual, or according to the conditions recommended by the manufacturer; for the general equipment, materials, reagents, etc. used, if not otherwise specified, they can be obtained from commercial channels.

[0024] Comparative Example 1 Premixing treatment was carried out on waste rubber powder of 20 mesh, lignin (Shandong Longli Biotechnology, enzymatically hydrolyzed lignin, by-product of corn straw), B480, tall oil, and sulfur powder with a mass ratio of 100:40.9:1:4:1 in a mixing tank. The rotation speed of the high-speed stirring mixer was 1000 rpm, the premixing treatment time was 12 minutes, and the premixing stirring temperature was 50°C; after the premixing treatment, the lignin waste rubber powder composite activation material A was prepared. Then, the lignin waste rubber powder composite material A, unactivated waste rubber powder of 60 mesh, light calcium, and SBS modifier (styrene-butadiene-styrene block copolymer) with a mass ratio of 100:20:20:3 were added to a kneader (Hebei Ruiwei Technology, screw refining machine) for kneading and blending. The kneading and blending temperature was 150°C, and the kneading and blending time was 10 minutes. Then, granulation was carried out in a granulator (Hebei Ruiwei Technology, cutting granulation system). The temperature of the barrel was controlled at 100°C, the rotation speed of the rotary knife was 200 rpm, and after granulation, it was naturally cooled through the conveying track and cooled by the air-blowing system, and lignin waste rubber powder composite material 1 was obtained from the discharge port; Comparative Example 2 Premixing treatment is carried out on waste rubber powder of 20 mesh, lignin (enzymatic hydrolysis lignin, by-product of corn straw, Shandong Longli Biotechnology Co., Ltd.), B480, and tall oil with a mass ratio of 100:25:1:4:0.8 in a stirring tank (50L stainless steel stirring tank, Shandong Jiade Machinery Co., Ltd.). The rotation speed of the high-speed stirring mixer is 1000 rpm, the premixing treatment time is 12 minutes, and the premixing stirring temperature is 50 °C. After premixing treatment, it enters the twin-screw extruder through the feeding guide rail and feeding port of the first-stage screw extruder (MRSRM rubber twin-screw extruder, Hebei Ruiwei Technology Co., Ltd.) for high-temperature shearing and desulfurization. The first-stage screw extruder is a co-rotating parallel twin-screw extruder with a screw diameter of 25 mm. The twin-screw has 8 temperature zones (the temperatures at the front and rear ends of the temperature zone are low, for adapting to temperature and extrusion cooling, and the temperature in the middle is high, as the main plasticization zone). The temperature of the barrel is controlled at 220 °C by an independent control console and a water-cooled circulating water tank system, and the screw rotation speed is 250 rpm. Then it directly enters a single-screw extruder (MRSRM rubber single-screw extruder, Hebei Ruiwei Technology Co., Ltd.) for further cooling and shaping. Under the combined action of the screw, kneading blocks, and high temperature, plasticization and modification are carried out. The screw diameter is 60 mm, the barrel temperature is controlled at 150 °C, and the screw rotation speed is 150 rpm to obtain lignin waste rubber powder composite activated material B. Lignin waste rubber powder composite activated material B, unactivated waste rubber powder of 60 mesh, light calcium, and SBS modifier (styrene-butadiene-styrene block copolymer) with a mass ratio of 100:20:20:3 are added to a mixer (screw refining machine, Hebei Ruiwei Technology Co., Ltd.) for mixing and blending. The temperature of mixing and blending is 150 °C, and the time of mixing and blending is 10 minutes. Then granulation is carried out in a granulator (cutting granulation system, Hebei Ruiwei Technology Co., Ltd.). The temperature of the barrel is controlled at 100 °C, and the rotation speed of the rotary knife is 200 rpm. After granulation, it is naturally cooled through the conveying track and cooled by the air-blowing system, and lignin waste rubber powder composite activated material 2 is obtained from the discharge port; Example

[0025] Premixing treatment is carried out on waste rubber powder of 20 mesh, lignin (enzymatic hydrolysis lignin, by-product of corn straw from Shandong Longli Biotechnology Co., Ltd.), B480, tall oil, and sulfur powder with a mass ratio of 100:40.9:1:4:1 in a stirring tank (50L stainless steel stirring tank from Shandong Jiade Machinery Co., Ltd.). The rotation speed of the high-speed stirring mixer is 1000 rpm, the premixing treatment time is 12 minutes, and the premixing stirring temperature is 50 °C. After the premixing treatment, it enters the twin-screw extruder through the feeding guide rail and feeding port of the first-stage screw extruder (MRSRM rubber twin-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for high-temperature shearing and desulfurization. The first-stage screw extruder is a co-rotating parallel twin-screw extruder with a screw diameter of 25 mm. The twin-screw has 8 temperature zones (the temperatures at the front and rear ends of the temperature zone are low, for adapting to temperature and extrusion cooling, and the temperature in the middle is high, which is the main plasticization zone). The temperature of the barrel is controlled at 220 °C by an independent control console and a water-cooled circulating water tank system, and the screw rotation speed is 250 rpm. Then it directly enters a single-screw extruder (MRSRM rubber single-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for further cooling and shaping. Under the combined action of the screw, kneading blocks, and high temperature, plasticization and modification are carried out. The screw diameter is 60 mm, the barrel temperature is controlled at 150 °C, and the screw rotation speed is 150 rpm to prepare the lignin waste rubber powder composite activated material C. The lignin waste rubber powder composite activated material C, unactivated 60-mesh waste rubber powder, light calcium, and SBS modifier (styrene-butadiene-styrene block copolymer) with a mass ratio of 100:20:20:3 are added to a mixer (screw refining machine from Hebei Ruiwei Technology Co., Ltd.) for mixing and blending. The temperature of the mixing and blending is 150 °C, and the time is 10 minutes. Then granulation is carried out in a granulator (cutting granulation system from Hebei Ruiwei Technology Co., Ltd.). The temperature of the barrel is controlled at 100 °C, and the rotation speed of the rotating knife is 200 rpm. After granulation, it is naturally cooled through the conveying track and cooled by the air-blowing system, and the lignin waste rubber powder composite activated material 3 is obtained from the discharge port; Example

[0026] Premixing treatment is carried out on waste rubber powder of 20 mesh, lignin (enzymatic hydrolysis lignin, by-product of corn straw, from Shandong Longli Biotechnology Co., Ltd.), B480, tall oil, and sulfur powder with a mass ratio of 100:60.7:1:4:1 in a stirring tank (50L stainless steel stirring tank from Shandong Jiade Machinery Co., Ltd.). The rotation speed of the high-speed stirring mixer is 1000 rpm, the premixing treatment time is 12 minutes, and the premixing stirring temperature is 50°C. After premixing treatment, it enters the twin-screw extruder through the feeding guide rail and feeding port of the first-stage screw extruder (MRSRM rubber twin-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for high-temperature shearing and desulfurization. The first-stage screw extruder is a co-rotating parallel twin-screw extruder with a screw diameter of 25 mm. The twin-screw has 8 temperature zones (the temperatures at the front and rear ends of the temperature zones are low, for adapting to temperature and extrusion cooling, and the temperature in the middle is high, as the main plasticization zone). The temperature of the barrel is controlled at 220°C by an independent control console and a water-cooled circulating water tank system, and the screw rotation speed is 250 rpm. Then it directly enters a single-screw extruder (MRSRM rubber single-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for further cooling and shaping. Under the combined action of the screw, kneading blocks, and high temperature, plasticization and modification are carried out. The screw diameter is 60 mm, the barrel temperature is controlled at 150°C, and the screw rotation speed is 150 rpm to prepare the lignin waste rubber powder composite activated material D. The lignin waste rubber powder composite activated material D, unactivated 60-mesh waste rubber powder, light calcium, and SBS modifier (styrene-butadiene-styrene block copolymer) with a mass ratio of 100:20:20:3 are added to a mixer (screw refining machine from Hebei Ruiwei Technology Co., Ltd.) for mixing and blending. The mixing and blending temperature is 150°C, and the mixing and blending time is 10 minutes. Then granulation is carried out in a granulator (cutting granulation system from Hebei Ruiwei Technology Co., Ltd.). The temperature of the barrel is controlled at 100°C, and the rotation speed of the rotating knife is 200 rpm. After granulation, it is naturally cooled through the conveying track and cooled by the air-blowing system, and the lignin waste rubber powder composite activated material 4 is obtained from the discharge port; Example

[0027] Premixing treatment is carried out on waste rubber powder of 20 mesh, lignin (enzymatic hydrolysis lignin, by-product of corn straw, from Shandong Longli Biotech Co., Ltd.), B480, tall oil, and sulfur powder with a mass ratio of 100:98:1:4:1.2 in a stirring tank (a 50L stainless steel stirring tank from Shandong Jiade Machinery Co., Ltd.). The rotation speed of the high-speed stirring mixer is 1000 rpm, the premixing treatment time is 12 minutes, and the premixing stirring temperature is 50 °C. After premixing treatment, it enters the twin-screw extruder through the feeding guide rail and feeding port of the first-stage screw extruder (MRSRM rubber twin-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for high-temperature shearing and desulfurization. The first-stage screw extruder is a co-rotating parallel twin-screw extruder with a screw diameter of 25 mm. The twin-screw has 8 temperature zones (the temperatures at the front and rear ends of the temperature zone are low, for adapting to temperature and extrusion cooling, and the temperature in the middle is high, which is the main plasticization zone). The temperature of the barrel is controlled at 220 °C by an independent control console and a water-cooled circulation water tank system, and the screw rotation speed is 250 rpm. Then it directly enters a single-screw extruder (MRSRM rubber single-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for further cooling and shaping. Under the combined action of the screw, kneading blocks, and high temperature, plasticization and modification are carried out. The screw diameter is 60 mm, the temperature of the barrel is controlled at 150 °C, and the screw rotation speed is 150 rpm to obtain the lignin waste rubber powder composite activation material E. The lignin waste rubber powder composite activation material E, unactivated 60-mesh waste rubber powder, light calcium, and SBS modifier (styrene-butadiene-styrene block copolymer) with a mass ratio of 100:20:20:3 are added to a kneader (screw refining machine from Hebei Ruiwei Technology Co., Ltd.) for kneading and blending. The temperature of kneading and blending is 150 °C, and the time of kneading and blending is 10 minutes. Then granulation is carried out in a granulator (cutting granulation system from Hebei Ruiwei Technology Co., Ltd.). The temperature of the barrel is controlled at 100 °C, and the rotation speed of the rotating knife is 200 rpm. After granulation, it is naturally cooled through the conveying track and cooled by the air-blowing system, and the lignin waste rubber powder composite activation material 5 is obtained from the discharge port; Example

[0028] Premixing treatment is carried out on waste rubber powder of 20 mesh, lignin (enzymatic hydrolysis lignin, by-product of corn straw, from Shandong Longli Biotechnology Co., Ltd.), B480, tall oil, and sulfur powder with a mass ratio of 100:148:1:4:1.5 in a stirring tank (50L stainless steel stirring tank from Shandong Jiade Machinery Co., Ltd.). The rotation speed of the high-speed stirring mixer is 1000 rpm, the premixing treatment time is 12 minutes, and the premixing stirring temperature is 50°C. After premixing treatment, it enters the twin-screw extruder through the feeding guide rail and feeding port of the first-stage screw extruder (MRSRM rubber twin-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for high-temperature shearing and desulfurization. The first-stage screw extruder is a co-rotating parallel twin-screw extruder with a screw diameter of 25 mm. The twin-screw has 8 temperature zones (the temperatures at the front and rear ends of the temperature zones are low, for adapting to temperature and extrusion cooling, and the temperature in the middle is high, as the main plasticization zone). The temperature of the barrel is controlled at 220°C by an independent control console and a water-cooled circulating water tank system, and the screw rotation speed is 250 rpm. Then it directly enters a single-screw extruder (MRSRM rubber single-screw extruder from Hebei Ruiwei Technology Co., Ltd.) for further cooling and forming. Under the combined action of the screw, kneading blocks, and high temperature, plasticization and modification are carried out. The screw diameter is 60 mm, the barrel temperature is controlled at 150°C, and the screw rotation speed is 150 rpm to prepare the lignin waste rubber powder composite activation material F. The lignin waste rubber powder composite activation material F, unactivated 60-mesh waste rubber powder, light calcium, and SBS modifier (styrene-butadiene-styrene block copolymer) with a mass ratio of 100:20:20:3 are added to a mixer (screw refining machine from Hebei Ruiwei Technology Co., Ltd.) for mixing and blending. The mixing and blending temperature is 150°C, and the mixing and blending time is 10 minutes. Then granulation is carried out in a granulator (cutting granulation system from Hebei Ruiwei Technology Co., Ltd.). The temperature of the barrel is controlled at 100°C, and the rotation speed of the rotary knife is 200 rpm. After granulation, it is naturally cooled through the conveying track and cooled by a blast system, and the lignin waste rubber powder composite activation material 6 is obtained from the discharge port. In the example, B480 belongs to alkylphenol polysulfide compounds and is purchased from Anhui Jinma Rubber Auxiliary Co., Ltd.

[0029] Add 70 - 75% of the lignin rubber powder composite material (referred to as the composite material) by mass of the matrix asphalt to the matrix asphalt at 185°C and stir for 15 minutes, then grind it once through a colloid mill, and finally stir and develop at 180°C for 2 hours and 7 hours to finally prepare the lignin rubber powder composite material modified asphalt 1 - 6. The specific proportions are shown in Table 2.

[0030]

[0031]

[0032] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

[0033] As can be seen from the data in Table 3, by comparing Comparative Example 1 with Example 1, it can be obtained that at the same proportion dosage, Example 1 processed by the process described in the present invention has better ductility performance, higher softening point and penetration, as well as better viscosity and segregation performance than Comparative Example 1. Thus, it can be seen that through the process described in the present invention, the temperature sensitivity of the modified asphalt is greatly reduced, and the high-temperature stability performance and low-temperature anti-cracking performance of the modified asphalt are enhanced. Example

[0034] The most typical raw materials and ratios: Premixed materials (mass ratio, unit: g): Waste rubber powder (20 mesh, waste tire crushed): 100 g Lignin (enzymatic hydrolysis lignin, corn straw by-product): 60 g Activator (phenyl disulfide, B480): 1 g Softening agent (tall oil): 4 g Stabilizer (sulfur powder): 0.5 g Banbury compounded materials (mass ratio, unit: g): Lignin waste rubber powder composite activation material: 100 g Unactivated waste rubber powder (60 mesh): 20 g Inorganic filler (light calcium): 20 g SBS modifier (star-shaped SBS): 3 g Process steps (based on the device of Example 1): 1) Premixing treatment: Add the above-mentioned premixed materials into a stirring tank (Shandong Jiade Machinery, 50L stainless steel stirring tank), set the stirring speed to 650 rpm, the premixing time to 8 minutes, and the premixing temperature to 60 °C to ensure uniform mixing of the materials.

[0035] 2) Twin-screw extrusion activation: The premixed materials enter a co-rotating parallel twin-screw extruder (Hebei Ruiwei Technology, MRSRM rubber twin-screw extruder) through an automatic feeding guide rail 3, and the parameters are set as follows: Screw diameter: 45 mm Temperature zone setting (8 temperature zones): the front section is 210 °C, the middle section is 230 °C, and the rear section is 210 °C Screw speed: 600 rpm The material undergoes high-temperature shearing and desulfurization in the twin-screw, and is then cooled to 80°C through the water-cooling circulation system (5).

[0036] 3) Single-screw extrusion molding: The activated material enters the single-screw extruder (Hebei Ruiwei Technology, MRSRM rubber single-screw extruder) through the connection port (6), and the parameters are set as follows: Screw speed: 150 rpm Barrel temperature: 150°C The material is further plasticized under the action of the screw and the kneading block to form a lignin waste rubber powder composite activated material.

[0037] 4) Internal mixer compounding: The composite activated material, unactivated rubber powder, light calcium, and SBS modifier (styrene-butadiene-styrene block copolymer) are added to the internal mixer (Hebei Ruiwei Technology, screw refining machine). The internal mixing temperature is set at 90°C, and the mixing time is 10 minutes to ensure uniform dispersion of each component.

[0038] 5) Pelletizing and cooling: The compounded material enters the pelletizer through the pelletizer feed port (10), and the parameters are set as follows: Rotating knife speed: 100 rpm Barrel temperature: 100°C The cut pellets are conveyed through the conveying track (12) and cooled to room temperature by the air-blowing system (13), and are finally packaged as finished products through the receiving port 14.

[0039] Performance testing: 71.4 g of the prepared composite modifier is incorporated into 100 g of matrix asphalt (70#A), stirred at 185°C for 15 minutes, ground by a colloid mill, and developed at 180°C for 2 hours. The test results are as follows (Table 4):

[0040] Performance data analysis: High-temperature performance: The softening point is increased by 11.8°C, significantly enhancing the rutting resistance ability; Low-temperature performance: The ductility at 5°C is increased by 68%, with excellent anti-cracking performance; Processing performance: The viscosity is reduced by 52.4%, improving the construction fluidity; Storage stability: The segregation temperature difference is only 0.3°C, far lower than the industry standard (≤2.5°C).

[0041] Conclusion: In this example, by optimizing the parameters (such as twin-screw speed, temperature gradient, material ratio), under the condition of 60% lignin content, the balance between high performance and low cost of the asphalt modifier is achieved, which fully meets the protection scope of the present invention.

[0042] The specific effects of the present invention are as follows: the softening point of the modified asphalt is increased by 1 - 12 °C, the ductility (at 5 °C) is increased by 1 - 6 cm, the penetration (at 25 °C) is increased by 0.5 - 2 mm, the dynamic viscosity of the modified asphalt (at 180 °C) is reduced by 30 - 50%, and the segregation performance in 24 hours is greatly improved.

[0043] From the comparison between Comparative Example 2 and Examples 2, 3, and 4, it can be seen that the modification process described in the present invention can significantly increase the dosage of lignin in the modifier and maintain good high-temperature stability of the modified asphalt. In Examples 2 and 3, the segregation performance of the modified asphalt is lower than that of Comparative Example 2, indicating that the co-pyrolysis effect of lignin and rubber powder in the modified asphalt is good, the properties of the modified asphalt are more uniform, and the dosage of rubber powder is reduced, thus achieving the effect of low-carbon emission reduction. In short, within the scope defined by the present invention, the performance of the modified asphalt can be comprehensively improved.

[0044] Infrared spectrum analysis was respectively carried out on the base asphalt, Comparative Example 2, Example 1, Example 2, Example 3, and Example 4 of the modified asphalt, and the results are as Figure 1 shown. It can be seen that the modified asphalt added with the lignin waste rubber powder composite activation material can correspond to the basic functional peaks of the base asphalt, which indicates that the basic properties of the modified asphalt have not changed compared with the base asphalt, and there is an additional peak at 3735 cm -1 for the modified asphalt compared with the base asphalt, which is the characteristic fatty hydroxyl peak of lignin, indicating that the modified asphalt has successfully completed the activation modification with lignin.

[0045] Scanning electron microscopy analysis was respectively carried out on the base asphalt, Comparative Example 2, Example 2, and Example 4 of the modified asphalt, and the results are as Figures 2 - 5 shown. The surface of the base asphalt is very smooth. In the modified asphalt of Comparative Example 2, obvious rubber powder particles can be seen, and the compatibility is poor. While the modified asphalt of Example 2 shows a flaky structure without obvious particle sense, indicating that the rubber powder particles in the lignin rubber powder composite modified asphalt form good compatibility with the asphalt. The modified asphalt of Example 4 also shows a sense of particles, indicating that the process described in the present invention is beneficial to the modification of asphalt in the range of high dosage of lignin in the modifier, making the modified asphalt more uniform and having good compatibility.

[0046] Rheological property tests were respectively carried out on the base asphalt, Comparative Example 2, Example 1, Example 2, Example 3, and Example 4 of the modified asphalt, and the rutting resistance factor was characterized. The rutting resistance factor reflects the high-temperature rutting resistance strain ability of the asphalt. The results are as Figure 6 shown. At high temperatures, the modified asphalt under the process of the present invention all shows better rutting resistance than the base asphalt, which makes it have strong anti-strain ability and rutting resistance on the highway pavement in summer. These also indicate that the high dosage of lignin brings better performance of the modified asphalt.

[0047] The lignin and waste rubber powder composite modified asphalt of the present invention well solves the problem of poor thermal storage stability of ordinary rubber powder modified asphalt. Especially when stored at high temperature for a long time, the performance changes little, the product is more resistant to aging and has a longer service life. The dosage of the lignin and waste rubber powder composite can reach more than 40% and even up to 60%, which is much higher than that of ordinary rubber powder modified asphalt (the rubber powder dosage is 20%). And even at a ratio of 40%, good performance indicators can still be achieved, greatly reducing the dosage of matrix asphalt and reducing the construction cost. It well solves the environmental pollution and resource waste problems of lignin and waste tires, and makes a contribution to "carbon peak" and "carbon neutrality".

[0048] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. A process for co-pyrolysis activation of waste rubber powder and lignin for use as an asphalt modifier. The main devices used include a stirring tank, a co-rotating parallel twin-screw extruder, a single-screw extruder, a mixer, and a granulator, which are connected in sequence; it is characterized in that: The materials are stirred in the mixing tank of the device. The co-rotating parallel twin-screw extruder is equipped with an independent control console (2) to control the temperature of each screw zone and the rotation speed. The automatic feeding guide rail (3) is connected to the feeding port (4) of the co-rotating parallel twin-screw extruder. The water-cooled circulating water tank system (5) is connected to the connection port (6) between the twin-screw extruder and the single-screw extruder. The materials are extruded from the discharge port (7) of the single-screw extruder. The internal mixer is provided with a feeding port (8). The upper cover (9) of the internal mixer is controlled to close the cover by its control console and lifting system. The granulator is provided with a feeding port (10) for feeding. The blade cutting system (11) inside the granulator is connected to the conveying track (12). The air-blowing system (13) is connected to the receiving port (14). including the steps of: 1) Materials including low-mesh waste rubber powder, lignin, activator, softener, stabilizer, etc. are first stirred and mixed evenly in the mixing tank (1). After premixing, the materials then enter the feeding port (4) through the automatic feeding guide rail (3) of the co-rotating parallel twin-screw extruder and enter the co-rotating parallel twin-screw extruder; 2) The premixed materials are subjected to high-temperature shearing and desulfurization in the co-rotating parallel twin-screw extruder. The independent control console (2) of the co-rotating parallel twin-screw extruder controls the temperature and rotation speed of each zone, and the temperature is cooled by its cooling circulating water tank (5); 3) After high-temperature shearing and desulfurization, the materials pass through the extrusion port of the co-rotating parallel twin-screw extruder to the connection port (6) of the single-screw extruder, and then are further cooled and formed by the single-screw extruder. Under the combined action of the screw, the engaging block and high temperature, plasticization and modification are carried out to obtain the lignin waste rubber powder composite activated material; 4) In the feeding port (8) of the internal mixer containing the lignin waste rubber powder composite activated material, unactivated high-mesh waste rubber powder, inorganic filler, SBS modifier (styrene-butadiene-styrene block copolymer) are added again. The upper cover (9) of the internal mixer controls the covering to mix evenly, then feeds through the feeding port (10) of the granulator, is cut by the blade cutting system (11) of the granulator, conveyed by the conveying track (12), cooled by air blowing of the air-blowing system (13), and enters the finished product and packaging bag from the receiving port (14) to obtain the composite modifier.

2. The process according to claim 1, wherein: The stirring speed of the mixing tank is 500 - 2000 rpm, preferably 600 - 650 rpm. The premixing time of the materials is 5 - 30 minutes, preferably 5 - 8 min. The premixing temperature is 40 - 100 °C, preferably 45 - 60 °C. The mass ratio of the waste rubber powder, lignin, activator, softener, stabilizer is: 100:45 - 155:1:4:0.5; among them, the waste rubber powder is 100 g as the formula reference amount, and other components are added in proportion. In step 4), in the internal mixer, the mass ratio of the lignin waste rubber powder composite activated material, unactivated high-mesh waste rubber powder, inorganic filler, SBS modifier (styrene-butadiene-styrene block copolymer) is 100:20:20:

3.

3. The process according to claim 1, characterized in that: The mesh number of the unactivated high-mesh waste rubber powder is 50 - 100 mesh, preferably 60 mesh; the mesh number of the low-mesh waste rubber powder is 5 - 20 mesh, preferably 20 mesh.

4. The process according to claim 1, characterized in that: During the activation extrusion process of the co-rotating parallel twin-screw extruder, the temperature of each barrel is 210 - 300 °C, preferably 210 - 230 °C, the screw diameter is 25 - 70 mm, preferably 30 - 45 mm, the twin-screw has 8 temperature zones, the screw speed is 550 - 650 rpm, preferably 550 - 600 rpm; the speed of the single-screw extruder is 50 - 350 rpm, preferably 100 - 150 rpm.

5. The process according to claim 1, characterized in that: The temperature of the internal mixer is 50 - 200 °C, preferably 60 - 90 °C; the rotational speed of the rotating knife of the granulator is 50 - 150 rpm; preferably 50 - 100 rpm.

6. The process according to claim 1, characterized in that: The lignin is one or two of hydrolyzed lignin, enzymatically hydrolyzed lignin, and alkali lignin, preferably a by-product of corn stover biorefining.

7. The process according to claim 1, characterized in that: The high-mesh waste rubber powder is one or several of the rubber powders prepared by pulverizing radial tires, non-radial tires, waste conveyor belts, and waste rubber shoes; the inorganic filler is one or several of montmorillonite, diatomite, hydrotalcite, kaolin, and light calcium carbonate.

8. The process according to claim 1, wherein: The SBS modifier (styrene-butadiene-styrene block copolymer) is star-shaped SBS or linear SBS.

9. The process according to claim 1, wherein: The activator is one or several of phenyl disulfide, benzenethiol, polyalkylphenol disulfide, and octadecylamine, preferably phenyl disulfide; the softener is one or several of aromatic oil, naphthenic oil, tall oil pitch, and rosin.

10. The process according to claim 1, characterized in that: The stabilizer is one or several of sulfur powder, dicumyl peroxide, di-tert-butylbenzene peroxide, accelerator TMTD, accelerator M, accelerator DM, zinc stearate, and maleimide.

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