A direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier and its preparation method and application

Abstract

A direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier and its preparation method and application belong to the technical field of new road materials. The raw materials of the direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier include the following components in parts by mass: 40-60 parts of elastomer, 15-30 parts of blocked isocyanate and blocked polyurethane prepolymer, 10-20 parts of plasticizer and 10-20 parts of low-grade asphalt, which are prepared by open-type banburying mixing and twin-screw melt blending and granulation. The fast-melting high-viscoelastic anti-fatigue asphalt modifier provided by the present invention has the characteristics of fast direct-cast melting speed, high viscosity and high elasticity, high fatigue resistance, and high and low temperature performance. It is suitable for application fields such as high-toughness ultra-thin overlays, high modulus anti-fatigue asphalt pavements, and semi-flexible pavements.

Description

Technical Field

[0001] The invention relates to the technical field of new road materials, and in particular to a direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier and a preparation method and application thereof. Background Art

[0002] High-performance asphalt binder is a key component to achieve the performance improvement of asphalt concrete. It plays a vital role in the high-temperature deformation resistance, low-temperature cracking resistance, fatigue life increase and road service life of asphalt pavement. At present, high-performance asphalt binder is mainly divided into two technical routes, finished high-performance modified asphalt and direct asphalt additive technology, each of which has its own advantages and disadvantages and application scenarios. Finished high-performance modified asphalt such as high-viscosity asphalt, high-elastic asphalt and high-modulus asphalt is suitable for large-scale projects. Although it has excellent performance, it is not flexible enough, the formula is not easy to adjust quickly and needs to occupy a special asphalt storage tank. In addition, long-term storage is prone to aging and segregation, resulting in a significant reduction in performance. Compared with finished asphalt, direct additives have the advantages of easy use, long-term storage, easy performance adjustment by dosage, strong mobility, etc., and are currently widely used. Direct modifiers work by first dry mixing and then wet mixing in the mixture during use. The mixing time is generally only about 1 min, so the high-temperature melting rate of the modifier is crucial to the degree of effect of the modifier.

[0003] As a high-performance asphalt binder, high-viscosity asphalt additives are currently mainly used in ultra-thin overlays, drainage pavements and other fields because of their advantages of increasing asphalt viscosity, improving the high and low temperature performance of the mixture, and reducing the dispersion of the mixture. Although some high-viscosity modifiers have better performance, there are not many studies on some application scenarios such as ultra-thin overlays, large bridge and tunnel paving, etc., which require improving the elastic recovery of asphalt, especially extending fatigue life. At present, the preparation of high-viscosity asphalt additives is mainly based on the technical path of composite modification of polymers such as SBS and other functional components. The Chinese patent application with publication number CN 114806193 A discloses a direct-cast high-viscosity asphalt modifier and its preparation method and application. It is mainly prepared from SEBS, viscous resin and other components. Although it can greatly increase the viscosity of asphalt, it does not pay attention to the elastic recovery of high-viscosity asphalt and the anti-fatigue performance of the mixture. The Chinese patent application with publication number CN 109553991 A discloses a high-viscosity modified asphalt based on SBS / polyurethane composite and its preparation method. The modified asphalt is prepared by adopting the technical route of composite modification of SBS and reactive polyurethane materials. Although the performance indicators have reached the technical requirements of high-viscosity asphalt, the overall indicators are poor, and the elastic recovery and fatigue resistance of high-viscosity asphalt are not involved. In addition, as a wet modification method, its feasibility as a direct-cast modifier has not been studied. The Chinese patent application with publication number CN 114163811 A discloses a multi-energy-efficient thin layer modifier for a high-elastic ultra-thin overlay asphalt mixture, which is prepared by mixing thermoplastic elastomers with components such as polyvinyl butyral. Although the proposed multi-functional thin layer modifier can improve the fatigue resistance of the mixture to a certain extent, the dosage of the modifier is too high and the cost performance is low.

[0004] In summary, although the existing technologies are mostly related to the preparation of high-viscosity modifiers and high-viscosity asphalt and their performance research, there are few studies that can simultaneously meet the requirements of direct-injection instant modification, high viscosity and high elasticity, and especially improving anti-fatigue performance, and the overall application performance needs to be optimized and improved. Summary of the invention

[0005] Technical problem to be solved: In view of the problem in the prior art that conventional direct-throw high-viscosity asphalt modifiers cannot simultaneously achieve quick solubility, high viscosity and elasticity, and excellent anti-fatigue performance, the present invention proposes a direct-throw fast-melting high-viscosity and anti-fatigue asphalt modifier and its preparation method and application. The prepared asphalt modifier has the properties of direct-throw fast melting, high viscosity and elasticity, and anti-fatigue. The preparation method is simple, the prepared modifier can be stored for a long time, the dosage is easy to adjust, and it is easy to use. In addition, the modifier has a fast melting speed, does not need to increase the mixing time, and can appropriately reduce the mixing and discharging temperature.

[0006] Technical solution: The first object of the present invention is to provide a direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier, the raw materials of which are proportioned by mass as follows: 40-60 parts of elastomer, 15-30 parts of blocked isocyanate and blocked polyurethane prepolymer, 10-20 parts of plasticizer and 10-20 parts of low-grade asphalt;

[0007] The elastomer is a mixture of linear SBS (linear thermoplastic styrene butadiene rubber), star SBS (star thermoplastic styrene butadiene rubber) and styrene butadiene rubber in a mass ratio of 2:2:1 (through a reasonable ratio of the three materials, the high viscosity and high elasticity characteristics of the modified asphalt can be taken into account to the greatest extent);

[0008] The blocked isocyanate and the blocked polyurethane prepolymer include phenol blocked isocyanate and phenol blocked polyurethane prepolymer in a mass ratio of 1:2-1:1. The blocked isocyanate and the blocked polyurethane prepolymer can be deblocked to isocyanate and terminal isocyanate polyurethane prepolymer at 160-180°C. The isocyanate is at least two of 4,4-diphenylmethane diisocyanate (MDI), polymethylene polyphenyl polyisocyanate (PAPI) and isophorone diisocyanate (IPDI). The polyurethane prepolymer is prepared by reacting polymethylene polyphenyl polyisocyanate (PAPI) with polyether polyol. The isocyanate content of the polyurethane prepolymer is controlled at 10-25 wt%. The low-grade asphalt is asphalt with a needle penetration of less than 30.

[0009] Conventional isocyanates and polyurethane prepolymers have poor storage stability and are easily reacted with moisture in the air and active hydrogen in chemical materials. Based on the technical route of the direct-addition modifier of the present invention, in order to ensure that isocyanates and polyurethane prepolymers do not react during the preparation of the modifier (active components such as hydroxyl groups exist in low-grade asphalt; in addition, the production temperature of the modifier is relatively low, less than 120°C), the end-blocking is unblocked during the direct-addition dry mixing process to react with the active hydrogen in the asphalt. By selecting a suitable end-blocking agent, the unblocking temperature of the blocked isocyanate and blocked polyurethane prepolymer is controlled to 160-180°C, which is close to the mixing temperature. Under this temperature condition, most of the phenol produced by unblocking after direct-addition dry mixing reaches the boiling point and volatilizes.

[0010] On the one hand, the introduction of low-grade asphalt can be miscible with the elastomer melt, increasing the solubility and compatibility with asphalt during direct dry mixing. On the other hand, it can well coat and isolate the isocyanate and polyurethane prepolymer system, achieving material stability and subsequent granulation and long-term storage.

[0011] Furthermore, the polyether polyol includes at least one of polyoxypropylene glycol (PPG) and polytetramethylene ether glycol (PTMEG).

[0012] The introduction of isocyanate and polyurethane prepolymer can give full play to the principle of chemical modification, and can react with functional groups such as pyrrole, indole, carbazole, phenols, and carboxylic acid in asphalt to generate chemical bonds such as carbamate and urea. Studies have shown that it can improve the high temperature and fatigue resistance of asphalt. By introducing low molecular weight isocyanate and high molecular weight polyurethane prepolymer at the same time, the high content of active isocyanate in low molecular weight isocyanate can play a high temperature modification role, and polyurethane prepolymer can achieve asphalt flexibility and toughness. The combination of the two can achieve the reduction of modifier dosage and the balance of performance. By controlling the dosage and isocyanate content of isocyanate and polyurethane prepolymer, and generating physical-chemical synergistic effects with polymers such as SBS, a multiple network structure is formed to achieve high viscoelasticity and fatigue resistance of asphalt binder. In addition, the isocyanate content of polyurethane prepolymer is controlled and the type of isocyanate is selected to achieve excessive isocyanate content. After the asphalt mixture is paved and rolled, it will be affected by moisture in the air and maintained, and the performance of the asphalt mixture will continue to increase.

[0013] Preferably, the plasticizer is a mixture of aromatic oil and dioctyl phthalate (DOP) in a mass ratio of 3-5:1.

[0014] Preferably, the asphalt is at least one of rock asphalt, lake asphalt, hard asphalt and anti-rutting masterbatch.

[0015] The present invention is aimed at the technical problem that conventional direct-cast high-viscosity asphalt modifiers cannot simultaneously achieve instant dissolution, high viscosity elasticity and excellent fatigue resistance. Through the method of physical and chemical composite modification of elastomers and polyurethanes, with the help of the technical path of isocyanate and polyurethane prepolymer blocking and the preparation method of the mixed system first mixing and then twin-screw granulation, a single particle type direct-cast instant modifier is prepared by regulating the amount and key parameters of materials such as elastomers, plasticizing components, and blocked isocyanates. Compared with the method of preparing modified asphalt in advance in a modified asphalt factory or on-site storage tank for SBS / liquid polyurethane modified asphalt, the operation is simpler. In addition, compared with the direct addition of liquid and other additives in the mixing station, it does not require a special liquid and other feeding system, and can simply adjust the performance by the dosage of the granular direct-cast instant modifier, which is flexible and maneuverable, does not need to increase the mixing time, and greatly reduces the difficulty of production operation.

[0016] The second object of the present invention is to provide a method for preparing the above-mentioned direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier, the steps of which are as follows:

[0017] Step 1, reacting excess isocyanate with polyether polyol to obtain an isocyanate-terminated polyurethane prepolymer;

[0018] Step 2: reacting isocyanate with phenol under the action of a catalyst to obtain blocked isocyanate; reacting the product of step 1 with phenol under the action of a catalyst to obtain a blocked polyurethane prepolymer;

[0019] Step 3, mixing the blocked isocyanate and the blocked polyurethane prepolymer with the plasticizer, the elastomer and the low-grade asphalt in an open internal mixer;

[0020] Step 4: Add the mixture prepared in step 3 to the feeding port of the twin-screw extruder by forced feeding, and melt blend and granulate at a temperature range of 80-110°C to obtain a direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier. Since the solubility parameters of elastic polymers such as SBS and aromatic oils and plasticizers are similar, the oil filling process during the stirring process is different from that of conventional SBS and naphthenic oil, which is manifested as partial plasticization and agglomeration of SBS, and conventional high-speed mixers and other stirring equipment are blocked and cannot work. It is necessary to preferably use an open internal mixer to mix the materials.

[0021] As a preference, the steps are as follows:

[0022] Step 1, dehydrating the polyether polyol at 120° C. under nitrogen conditions, adding isocyanate dropwise to the dehydrated polyether polyol according to a ratio of n(NCO):n(OH) of 5:1-20:1, and reacting at 60-90° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining an isocyanate-terminated polyurethane prepolymer;

[0023] Step 2: adding phenol to isocyanate at a ratio of n(NCO):n(OH) of 1:1.05-1:1.1, adding 0.3-0.6 wt% of dibutyltin dilaurate catalyst, reacting at 50-90°C under nitrogen until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; adding phenol to the product of step 1 at a ratio of n(NCO):n(OH) of 1:1.05-1:1.1, adding 0.3-0.6 wt% of dibutyltin dilaurate catalyst, reacting at 50-90°C under nitrogen until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0024] Step 3: Mix the blocked isocyanate and blocked polyurethane prepolymer produced in step 2 with the plasticizer, elastomer and low-grade asphalt in an open internal mixer according to the mass ratio for 3-6 minutes;

[0025] Step 4: Add the mixture prepared in step 3 into the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 80-110° C. to obtain a direct-throw fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0026] The third purpose of the present invention is the application of the above-mentioned direct-thrown fast-melting high-viscosity elastic anti-fatigue asphalt modifier in the preparation of asphalt mixture. The specific steps are as follows: directly add the direct-thrown fast-melting high-viscosity elastic anti-fatigue asphalt modifier at a dosage of 0.25-0.55 wt% of the asphalt mixture into the aggregate at 170-185°C for dry mixing, and then add asphalt and mineral powder to mix. The discharge temperature of the prepared asphalt mixture is 170-180°C.

[0027] Since the melting characteristics of the modifier are fully considered during the development of the direct-cast instant high-viscosity elastic anti-fatigue modifier, it can achieve rapid dispersion and melting during the aggregate mixing process (melting index of 140℃ / 2.16kg is greater than 5g / 10min, and melting index of 170℃ / 2.16kg is greater than 15g / 10min), which will increase the viscosity of the modified asphalt at low temperatures, but will not increase the viscosity of the asphalt at high temperatures. Compared with conventional high-viscosity asphalt mixtures, the mixing and discharging temperatures of the mixture of the present invention can be reduced by about 10℃.

[0028] Beneficial effects: Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] (1) The present invention uses the technical principle of improving the stability of isocyanate and polyurethane prepolymer by phenol end-capping, and realizes melt blending and granulation with elastomer materials under relatively low temperature conditions by means of a preparation method of internal mixing and twin-screw melt blending. It has the advantages of simple preparation method, long-term storage of modifier, easy adjustment of dosage, and convenient use. In addition, the modifier melts quickly, does not need to increase the mixing time, and can appropriately reduce the mixing and discharge temperatures.

[0030] (2) The phenol-terminated isocyanate and the polyurethane prepolymer components can be deblocked at a temperature of 160-180°C during the direct dry mixing process. The generated isocyanate and polyurethane prepolymer can play a synergistic modification role with the elastomer component, greatly improving the viscoelasticity of the modified asphalt and the fatigue resistance and comprehensive performance of the mixture. The prepared high-viscoelastic modified asphalt has a dynamic viscosity of more than 450,000 Pas at 60°C, an elastic recovery of more than 85% at 5°C, and a modulus decrease of no more than 30% in the fatigue performance (15°C, 600µε) of the mixture after 1 million times.

[0031] (3) The modifier dosage is low, and it can modify the base asphalt or SBS modified asphalt, which can effectively reduce the cost compared with other modifiers. When the base asphalt uses SBS modified asphalt, the modifier dosage is even lower. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0033] The types of materials used in the examples of this specification are as follows:

[0034] Linear SBS: SBS791H (Baling Branch of China Petrochemical Asset Management Co., Ltd.), SBS3501 (Huizhou LCY Rubber Co., Ltd.).

[0035] Star-type SBS: SBS LG411 (LG Chemical of South Korea), SBS4303 (Baling Branch of China Petrochemical Group Asset Management Co., Ltd.), SBS D1102 (Kraton Chemical of the United States).

[0036] Styrene butadiene rubber: SBR1502 (Shandong Xianyuan Chemical Technology Co., Ltd.).

[0037] Isocyanates: MDI (MDI-50, MDI-100), PAPI (PM100, PM200), and IPDI were purchased from Wanhua Chemical Group Co., Ltd.

[0038] Polyether polyol: PPG (PPG-400, PPG-1000, Hai'an Petrochemical Plant, Jiangsu Province), PTMEG (PTMEG1000, PTMEG2000, Ningwu New Material Technology Co., Ltd.).

[0039] SBS asphalt: SBS asphalt ID, Jiangsu Baoli Asphalt Co., Ltd., meets the relevant requirements of JTG F40-2004.

[0040] Rock asphalt: Anhui Zhongyin Natural Rock Asphalt Co., Ltd., natural asphalt content ≥ 20%.

[0041] Lake asphalt: Trinidad Asphalt (Beijing) Co., Ltd., needle penetration 1-4 (0.1mm), softening point 93-99℃.

[0042] Hard asphalt: Sinopec Donghai brand hard asphalt, needle penetration 30 (0.1mm).

[0043] Lignin fiber: flocculent commercially available wood fiber that meets the technical requirements of JT / T 533-2020.

[0044] Aromatic oil: Shandong Taichang Petrochemical Technology Co., Ltd., aromatic content ≥85%.

[0045] Anti-rutting masterbatch: China Petrochemical Corporation Luoyang Branch, softening point 110℃.

[0046] Commercially available high-viscosity and high-elastic asphalt modifier: Go Green Lihong high-viscosity asphalt modifier, Shanghai Lihong New Materials Co., Ltd.

[0047] Mixture gradation: The mixture gradation used in the following examples and comparative examples is consistent, all of which adopt ultra-thin cover dense gradation (void ratio controlled between 3.5-5.0%), the maximum nominal particle size of aggregate is 8 mm, and the actual asphalt-stone ratio (modifier + asphalt) is 6.0%. Example 1

[0048] Preparation of modifier:

[0049] S1. Dehydrate polyether polyol PPG-400 at 120° C. under nitrogen conditions, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 5:1, and react at 60° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining an isocyanate-terminated polyurethane prepolymer (isocyanate content 10wt%);

[0050] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to MDI-50, PM100 (mass ratio 1:1) isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the product of S1, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 75°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0051] S3, 20 parts of the blocked isocyanate and blocked polyurethane prepolymer (the mass ratio of the two is 1:2) S2 product, 15 parts of plasticizer (aromatic oil and DOP are in a mass ratio of 3:1), 50 parts of elastomer (SBS791H, SBS LG411, SBR1502 are in a mass ratio of 2:2:1), and 20 parts of rock asphalt are mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0052] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 80-100° C. to obtain a direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0053] Preparation of modified asphalt:

[0054] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0055] Preparation of modified asphalt mixture:

[0056] 0.45 wt% quick-melting modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry-mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance stabilized. Example 2

[0057] Preparation of modifier:

[0058] S1. Dehydrate polyether polyol PPG-1000 at 120° C. under nitrogen, add PM200 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 20:1, and react at 90° C. under nitrogen until the isocyanate content of the synthesized product reaches the theoretical value range, to obtain an isocyanate-terminated polyurethane prepolymer (isocyanate content 25wt%);

[0059] S2, according to the ratio of n(NCO):n(OH) of 1:1.1, phenol was added to MDI-100, PM200 (mass ratio 1:1) isocyanate, and 0.6 wt% of dibutyltin dilaurate catalyst was added, and the reaction was carried out at 90°C under nitrogen conditions until the residual isocyanate content of the synthesized product was less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) of 1:1.05, phenol was added to the product of S1, and 0.4 wt% of dibutyltin dilaurate catalyst was added, and the reaction was carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product was less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0060] S3, 30 parts of blocked isocyanate and blocked polyurethane prepolymer (mass ratio of 1:1) S2 product, 20 parts of plasticizer (mass ratio of aromatic oil and DOP 5:1), 40 parts of elastomer (mass ratio of SBS3501, SBS4303, SBR1502 2:2:1), 15 parts of lake asphalt are mixed in an open internal mixer according to mass ratio for 6 minutes;

[0061] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 90-110°C to obtain a direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0062] Preparation of modified asphalt:

[0063] Heat 100 parts of 70# asphalt to 160°C, add 9.5 parts of modifier, and stir at 500 rpm for 30 min to prepare modified asphalt. Place at room temperature for 7 days for performance testing.

[0064] Preparation of modified asphalt mixture:

[0065] 0.55 wt% quick-melting modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry-mixed for 30 s, then 70# asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stabilized. Example 3

[0066] Preparation of modifier:

[0067] S1. Dehydrate polyether polyol PTMEG1000 at 120° C. under nitrogen conditions, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 10:1, and react at 80° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining a terminal isocyanate polyurethane prepolymer (isocyanate content 16wt%);

[0068] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to MDI-100, PM100, IPDI (mass ratio 1:1:1) isocyanate, and 0.4 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 90°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the product of S1, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 90°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0069] S3, 15 parts of the blocked isocyanate and blocked polyurethane prepolymer (mass ratio of 1:1) S2 product, 10 parts of plasticizer (mass ratio of aromatic oil and DOP 4:1), 60 parts of elastomer (mass ratio of SBS791H, SBS D1102, SBR1502 2:2:1), 10 parts of hard asphalt are mixed in an open internal mixer according to the mass ratio for 3 min;

[0070] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 80-110°C to obtain a direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0071] Preparation of modified asphalt:

[0072] 100 parts of SBS asphalt were heated to 165°C, 5.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0073] Preparation of modified asphalt mixture:

[0074] 0.35 wt% quick-melting modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry-mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance stabilized. Example 4

[0075] Preparation of modifier:

[0076] S1. Dehydrate polyether polyol PPG-400 and PTMEG1000 at a mass ratio of 1:1 at 120°C under nitrogen conditions, add PM200 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 8:1, and react at 70°C under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, to obtain a terminal isocyanate polyurethane prepolymer (isocyanate content 13.5 wt%);

[0077] S2, according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to PM100, IPDI (mass ratio 1:1) isocyanate, and 0.5 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 70°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to the product of S1, and 0.5 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 80°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0078] S3, 25 parts of blocked isocyanate and blocked polyurethane prepolymer (mass ratio of 1:1.5) S2 product, 15 parts of plasticizer (aromatic oil and DOP mass ratio of 5:1), 55 parts of elastomer (SBS3501, SBS4303, SBR1502 mass ratio of 2:2:1), 15 parts of anti-rutting masterbatch are mixed in an open internal mixer according to mass ratio for 4 min;

[0079] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 80-100° C. to obtain a direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0080] Preparation of modified asphalt:

[0081] Heat 100 parts of 90# asphalt to 165°C, add 7.5 parts of modifier, and stir at 500 rpm for 30 min to prepare modified asphalt. Place at room temperature for 7 days for performance testing.

[0082] Preparation of modified asphalt mixture:

[0083] 0.45 wt% quick-melting modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry-mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance stabilized. Example 5

[0084] Preparation of modifier:

[0085] S1. Dehydrate polyether polyol PTMEG2000 at 120° C. under nitrogen conditions, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 17.5:1, and react at 75° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining a terminal isocyanate polyurethane prepolymer (isocyanate content 22.5 wt%);

[0086] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to PM200, IPDI (mass ratio 1:1) isocyanate, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 80°C and nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to the product of S1, and 0.4 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C and nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0087] S3, 30 parts of the blocked isocyanate and blocked polyurethane prepolymer (mass ratio of 1:2) S2 product, 20 parts of plasticizer (mass ratio of aromatic oil and DOP 4:1), 60 parts of elastomer (mass ratio of SBS3501, SBS D1102, SBR1502 2:2:1), 20 parts of low-grade asphalt (mass ratio of rock asphalt: hard asphalt 1:1) were mixed in an open internal mixer according to the mass ratio for 6 minutes;

[0088] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 85-105°C to obtain a direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0089] Preparation of modified asphalt:

[0090] 100 parts of SBS asphalt were heated to 165°C, 4 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0091] Preparation of modified asphalt mixture:

[0092] 0.25 wt% quick-melting modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry-mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance stabilized. Example 6

[0093] Preparation of modifier:

[0094] S1. Dehydrate polyether polyol PPG-1000 and PTMEG2000 at a mass ratio of 1:1 at 120°C under nitrogen conditions, add PM200 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 12:1, and react at 90°C under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, to obtain a terminal isocyanate polyurethane prepolymer (isocyanate content 18 wt%);

[0095] S2. According to the ratio of n(NCO):n(OH) of 1:1.1, phenol was added to MDI-100, PM200, IPDI (mass ratio of 1:1:1) isocyanate, and 0.4 wt% of dibutyltin dilaurate catalyst was added, and the reaction was carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product was less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) of 1:1.1, phenol was added to the product of S1, and 0.3 wt% of dibutyltin dilaurate catalyst was added, and the reaction was carried out at 90°C under nitrogen conditions until the residual isocyanate content of the synthesized product was less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0096] S3, 20 parts of the blocked isocyanate and blocked polyurethane prepolymer (mass ratio of 1:2) S2 products, 10 parts of plasticizer (mass ratio of aromatic oil and DOP 5:1), 40 parts of elastomer (mass ratio of SBS791H, SBS LG411, SBR1502 2:2:1), 10 parts of low-grade asphalt (mass ratio of hard asphalt: anti-rutting masterbatch 1:1) were mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0097] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 80-105°C to obtain a direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0098] Preparation of modified asphalt:

[0099] Heat 100 parts of 70 asphalt to 160°C, add 6 parts of modifier, and stir at 500 rpm for 30 min to prepare modified asphalt. Place it at room temperature for 7 days for performance testing.

[0100] Preparation of modified asphalt mixture:

[0101] 0.35 wt% quick-melting modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry-mixed for 30 s, then 70# asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance stabilized. Comparative Example 1

[0102] Same as Example 1, except that the contents of the elastomer and the terminal isocyanate and terminal polyurethane prepolymers are not within the set range, as follows:

[0103] Preparation of modifier:

[0104] S1. Dehydrate polyether polyol PPG-400 at 120° C. under nitrogen, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 5:1, and react at 60° C. under nitrogen until the isocyanate content of the synthesized product reaches the theoretical value range, to obtain an isocyanate-terminated polyurethane prepolymer (isocyanate content 10 wt%);

[0105] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to MDI-50, PM100 (mass ratio 1:1) isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the product of S1, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 75°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0106] S3, 10 parts of the blocked isocyanate and blocked polyurethane prepolymer (the mass ratio of the two is 1:2) S2 product, 15 parts of plasticizer (aromatic oil and DOP are in a mass ratio of 3:1), 65 parts of elastomer (SBS791H, SBS LG411, SBR1502 are in a mass ratio of 2:2:1), and 20 parts of rock asphalt are mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0107] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, perform melt blending and granulation at a temperature range of 80-100° C., and obtain an asphalt modifier.

[0108] Preparation of modified asphalt:

[0109] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0110] Preparation of modified asphalt mixture:

[0111] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable. Comparative Example 2

[0112] Same as Example 1, except that the elastomer content and the type of plasticizer are not within the set range.

[0113] Preparation of modifier:

[0114] S1. Dehydrate polyether polyol PPG-400 at 120° C. under nitrogen conditions, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 5:1, and react at 60° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining an isocyanate-terminated polyurethane prepolymer (isocyanate content 10wt%);

[0115] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to MDI-50, PM100 (mass ratio 1:1) isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the product of S1, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 75°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0116] S3, 20 parts of the blocked isocyanate and blocked polyurethane prepolymer (the mass ratio of the two is 1:2) S2 product, 15 parts of plasticizer (the mass ratio of naphthenic oil and DOP is 3:1), 20 parts of elastomer (the mass ratio of SBS791H, SBS LG411, and SBR1502 is 2:2:1), and 20 parts of rock asphalt are mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0117] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, perform melt blending and granulation at a temperature range of 80-100° C., and obtain an asphalt modifier.

[0118] Preparation of modified asphalt:

[0119] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0120] Preparation of modified asphalt mixture:

[0121] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable. Comparative Example 3

[0122] Same as Example 1, except that the terminal isocyanate and terminal polyurethane prepolymer are missing. The details are as follows:

[0123] Preparation of modifier:

[0124] S1. Mix 15 parts of plasticizer (aromatic oil and DOP in a mass ratio of 3:1), 50 parts of elastomer (SBS791H, SBSLG411, and SBR1502 in a mass ratio of 2:2:1), and 20 parts of rock asphalt in an open internal mixer according to the mass ratio for 5 minutes;

[0125] S2. The S1 product is added to the feeding port of a twin-screw extruder through a forced feeding system, and melt-blended and granulated at a temperature range of 80-100° C. to obtain an asphalt modifier.

[0126] Preparation of modified asphalt:

[0127] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0128] Preparation of modified asphalt mixture:

[0129] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable. Comparative Example 4

[0130] Same as Example 1, except that there is only terminal isocyanate and no terminal polyurethane prepolymer. The details are as follows:

[0131] Preparation of modifier:

[0132] S1. According to the ratio of n(NCO):n(OH) of 1:1.05, phenol was added to MDI-50 and PM100 (mass ratio of 1:1) isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst was added, and the mixture was reacted at 50°C under nitrogen until the residual isocyanate content of the synthesized product was less than 0.1 wt%, thereby obtaining blocked isocyanate;

[0133] S2, 20 parts of blocked isocyanate, 15 parts of plasticizer (aromatic oil and DOP in a mass ratio of 3:1), 50 parts of elastomer (SBS791H, SBS LG411, SBR1502 in a mass ratio of 2:2:1), and 20 parts of rock asphalt were mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0134] S3. The S3 product is added to the feeding port of the twin-screw extruder through a forced feeding system, and melt-blended and granulated at a temperature range of 80-100° C. to obtain an asphalt modifier.

[0135] Preparation of modified asphalt:

[0136] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0137] Preparation of modified asphalt mixture:

[0138] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable. Comparative Example 5

[0139] Same as Example 1, except that the isocyanate content is not within the set range.

[0140] Preparation of modifier:

[0141] S1. Dehydrate polyether polyol PPG-400 at 120° C. under nitrogen conditions, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 3:1, and react at 60° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining a terminal isocyanate polyurethane prepolymer (isocyanate content 6wt%);

[0142] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to MDI-50, PM100 (mass ratio 1:1) isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the product of S1, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 75°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0143] S3, 20 parts of the blocked isocyanate and blocked polyurethane prepolymer (the mass ratio of the two is 1:2) S2 product, 15 parts of plasticizer (aromatic oil and DOP are in a mass ratio of 3:1), 50 parts of elastomer (SBS791H, SBS LG411, SBR1502 are in a mass ratio of 2:2:1), and 20 parts of rock asphalt are mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0144] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, perform melt blending and granulation at a temperature range of 80-100° C., and obtain an asphalt modifier.

[0145] Preparation of modified asphalt:

[0146] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0147] Preparation of modified asphalt mixture:

[0148] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable. Comparative Example 6

[0149] Same as Example 1, except that the types of terminal isocyanate and terminal polyurethane materials are not within the set range.

[0150] Preparation of modifier:

[0151] S1. Dehydrate the polyether polyol PPG-400 at 120° C. under nitrogen conditions, add TDI-100 isocyanate (2,4-toluene diisocyanate) dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 5:1, and react at 60° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining a terminal isocyanate polyurethane prepolymer (isocyanate content 10 wt%);

[0152] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to TDI-100 isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the S1 product, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 75°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0153] S3, 20 parts of the blocked isocyanate and blocked polyurethane prepolymer (the mass ratio of the two is 1:2) S2 product, 15 parts of plasticizer (aromatic oil and DOP are in a mass ratio of 3:1), 50 parts of elastomer (SBS791H, SBS LG411, SBR1502 are in a mass ratio of 2:2:1), and 20 parts of rock asphalt are mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0154] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, perform melt blending and granulation at a temperature range of 80-100° C., and obtain an asphalt modifier.

[0155] Preparation of modified asphalt:

[0156] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0157] Preparation of modified asphalt mixture:

[0158] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable. Comparative Example 7

[0159] Same as Example 1, except that the content of plasticizer and low-grade asphalt is not within the set range.

[0160] Preparation of modifier:

[0161] S1. Dehydrate polyether polyol PPG-400 at 120° C. under nitrogen conditions, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 5:1, and react at 60° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining an isocyanate-terminated polyurethane prepolymer (isocyanate content 10wt%);

[0162] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to MDI-50, PM100 (mass ratio 1:1) isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the product of S1, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 75°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0163] S3, 20 parts of the blocked isocyanate and blocked polyurethane prepolymer (the mass ratio of the two is 1:2) S2 product, 5 parts of plasticizer (aromatic oil and DOP are in a mass ratio of 3:1), 50 parts of elastomer (SBS791H, SBS LG411, SBR1502 are in a mass ratio of 2:2:1), and 25 parts of rock asphalt are mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0164] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, perform melt blending and granulation at a temperature range of 80-100° C., and obtain an asphalt modifier.

[0165] Preparation of modified asphalt:

[0166] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0167] Preparation of modified asphalt mixture:

[0168] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 170℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable. Comparative Example 8

[0169] The same as Example 1, except that the preparation temperature of the modified asphalt is not within the set range of the blocked isocyanate / blocked polyurethane prepolymer deblocking in the modifier. The details are as follows:

[0170] Preparation of modifier:

[0171] S1. Dehydrate polyether polyol PPG-400 at 120° C. under nitrogen conditions, add PM100 isocyanate dropwise to the dehydrated polyol at a ratio of n(NCO):n(OH) of 5:1, and react at 60° C. under nitrogen conditions until the isocyanate content of the synthesized product reaches the theoretical value range, thereby obtaining an isocyanate-terminated polyurethane prepolymer (isocyanate content 10wt%);

[0172] S2, according to the ratio of n(NCO):n(OH) being 1:1.05, phenol is added to MDI-50, PM100 (mass ratio 1:1) isocyanate, and 0.3 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 50°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; according to the ratio of n(NCO):n(OH) being 1:1.1, phenol is added to the product of S1, and 0.6 wt% of dibutyltin dilaurate catalyst is added, and the reaction is carried out at 75°C under nitrogen conditions until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer;

[0173] S3, 20 parts of the blocked isocyanate and blocked polyurethane prepolymer (the mass ratio of the two is 1:2) S2 product, 15 parts of plasticizer (aromatic oil and DOP are in a mass ratio of 3:1), 50 parts of elastomer (SBS791H, SBS LG411, SBR1502 are in a mass ratio of 2:2:1), and 20 parts of rock asphalt are mixed in an open internal mixer according to the mass ratio for 5 minutes;

[0174] S4. Add the S3 product to the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 80-100° C. to obtain a direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

[0175] Preparation of modified asphalt:

[0176] 100 parts of SBS asphalt were heated to 150°C, 7.5 parts of modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The performance test was performed after the mixture was placed at room temperature for 7 days.

[0177] Preparation of modified asphalt mixture:

[0178] 0.45 wt% quick-melting modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 170-185℃ and dry-mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 165℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance stabilized. Comparative Example 9

[0179] This comparative example uses a commercially available high-viscosity and high-elastic asphalt modifier.

[0180] Preparation of modified asphalt:

[0181] 100 parts of SBS asphalt were heated to 165°C, 7.5 parts of commercially available high-viscosity and high-elastic asphalt modifier were added, and the mixture was stirred at 500 rpm for 30 min to prepare the modified asphalt. The mixture was placed at room temperature for 7 days for performance testing.

[0182] Preparation of modified asphalt mixture:

[0183] 0.45 wt% asphalt modifier and 0.3 wt% lignin fiber were directly added to the aggregate at 180-190℃ and dry mixed for 30 s, then SBS asphalt was added and mixed for 90 s, and finally mineral powder was added and mixed for 90 s to obtain asphalt mixture. The discharge temperature of the prepared asphalt mixture was 180℃, and the molded specimens were placed at room temperature for 7 days before testing after the performance was stable.

[0184] Table 1 Different direct-injection modifiers and the modified asphalt indicators prepared

[0185] Serial number 140℃ / 2.16kg Melt index (g / 10min) 170℃ / 2.16kg Melt index (g / 10min) 60℃ dynamic viscosity (10,000 Pas) 5℃ elastic recovery (%) Softening point (℃) Example 1 7.5 21.4 75.5 95 105.6 Example 2 10.2 30.6 68.4 92 101.4 Example 3 5.8 19.4 52.6 91 98.1 Example 4 8.3 24.8 50.6 89 95.4 Example 5 8.5 26.6 47.8 89 94.2 Example 6 6.8 20.3 45.2 86 92.4 Comparative Example 1 5.5 18.2 55.8 81 95.6 Comparative Example 2 14.2 36.8 53.5 73 92.5 Comparative Example 3 4.2 14.0 44.5 71 83.4 Comparative Example 4 7.3 20.8 61.2 83 96.6 Comparative Example 5 7.6 21.6 58.6 86 95.2 Comparative Example 6 7.2 19.2 63.5 87 99.2 Comparative Example 7 6.4 16.2 55.4 71 93.1 Comparative Example 8 7.5 21.4 51.3 73 93.5 Comparative Example 9 0.4 2.1 48.5 52 97.7

[0186] Table 2 Performance indexes of different ultra-thin overlay asphalt mixtures

[0187] Serial number 60℃ dynamic stability (times / mm) -10℃ low temperature strain (µε) 15℃ / 1000µε, 1 million times four-point fatigue modulus decrease percentage (%) Freeze-thaw splitting strength ratio (%) Example 1 13620 5150 15.5 93.6 Example 2 10455 4652 18.6 92.1 Example 3 11988 4624 22.0 89.5 Example 4 9562 4829 23.8 93.0 Example 5 8565 4052 24.1 88.4 Example 6 8910 4185 26.8 91.6 Comparative Example 1 8022 3643 44.2 89.2 Comparative Example 2 9125 3764 36.4 87.8 Comparative Example 3 7066 4045 47.8 92.5 Comparative Example 4 8734 4145 42.5 91.4 Comparative Example 5 8472 3990 35.6 88.4 Comparative Example 6 7828 3844 37.9 87.9 Comparative Example 7 7565 3456 34.4 91.2 Comparative Example 8 13280 5245 15.8 93.0 Comparative Example 9 8055 3650 65.6 86.1

[0188] The data in Table 1 and Table 2 are summaries of different modifier material indices, modified asphalt indices and mixture indices of the embodiments and comparative examples, respectively. The results show that the direct-throw fast-melting asphalt modifier of the present invention has excellent fast-melting characteristics, with a melting index of more than 5g / 10min at 140°C / 2.16kg and a melting index of more than 15g / 10min at 170°C / 2.16kg. In addition, compared with the comparative example, the embodiment shows excellent low-temperature elastic recovery, and the elastic recovery index at 5°C can be greater than 85%, which is much better than the comparative example. In addition, the dynamic viscosity of the modified asphalt at 60°C can be greater than 450,000 Pas, and the softening point of the modified asphalt is greater than 90°C, with better performance.

[0189] The mixture experiment shows that the modifier of the present invention, under the premise of reducing the mixing and compaction temperature by 5-10°C, the ultra-thin overlay mixture prepared shows excellent fatigue resistance, high and low temperature resistance and water damage resistance. In addition, the dosage of the modifier of the present invention is not high. When the benchmark asphalt is the base asphalt, the dosage of the modifier is 0.35-0.55% of the mixture. When the benchmark asphalt is SBS modified asphalt, the dosage of the modifier is 0.25-0.45% of the mixture. The modulus decrease of the mixture prepared by the embodiment of the present invention after 1 million times of fatigue performance (15°C, 600µε) does not exceed 30%, which is much better than that of comparative examples 1-8, and the percentage of modulus decrease is half of that of the commercial product of comparative example 9. The high-temperature dynamic stability index of the mixture prepared by the embodiment of the present invention is greater than 8000 times / mm, the low-temperature strain at -10°C is greater than 4000µε, the freeze-thaw splitting strength ratio is greater than 85%, and the comprehensive performance is excellent.

[0190] Compared with Example 1, the contents of elastomer and terminal isocyanate and terminal polyurethane prepolymer in Comparative Example 1 are not within the set range, specifically, the elastomer content is relatively high, while the terminal isocyanate and terminal polyurethane prepolymer content is relatively low. Terminal isocyanate and terminal polyurethane prepolymer cannot play the best composite modification effect of viscosity-increasing and elasticity-increasing with the elastomer, and in addition, the elastomer cannot be effectively plasticized. This is manifested in the decrease in the melt index of the modifier, the decrease in the dynamic viscosity and elastic recovery of the modified asphalt, and the obvious decrease in the fatigue performance of the asphalt mixture. Similarly, in Comparative Examples 2-7, the parameters such as the content and type of each component are not within the set range, resulting in the decrease in performance due to the inability to take into account both the viscoelasticity of the asphalt and the high and low temperature and fatigue performance of the mixture.

[0191] In Comparative Example 8, the preparation temperature of the modified asphalt is controlled outside the set range of the deblocking of the blocked isocyanate / blocked polyurethane prepolymer in the modifier. The preparation temperature of the modified asphalt is 150°C, and most of the blocked isocyanate and blocked polyurethane prepolymer in the modifier are not deblocked, and further no chemical reaction occurs with the asphalt, resulting in a significant decrease in the dynamic viscosity, elastic recovery and softening point indexes of the modified asphalt compared with Example 1. The preparation of the modifier and the mixture is not affected by the temperature of the deblocking section, so the melt index index of the modifier itself and the mixture index are basically unchanged.

[0192] Comparative Example 9 uses a commercially available high-viscosity modifier, which lacks the quick-melting, high-viscosity elastic and anti-fatigue system design of the present invention, and the melt index of the modifier is much lower than that of the embodiments of the present invention, and the quick-melting effect cannot be achieved. Although the 60°C dynamic viscosity of the modified asphalt in Comparative Example 9 and the high and low temperature performance of the mixture are slightly lower or not much different than those of the embodiments, the elastic recovery of the modified asphalt and the fatigue performance of the mixture are significantly lower than those of Example 1. This shows that the system design of the present invention has produced obvious beneficial effects compared with conventional technical solutions.

[0193] In summary, the fast-melting, high-viscosity and high-elasticity anti-fatigue asphalt modifier prepared by the present invention has the characteristics of fast direct melting speed, high viscosity and high elasticity, high fatigue resistance, and high and low temperature performance. It is suitable for application fields such as high-toughness ultra-thin overlays, high-modulus anti-fatigue asphalt pavements, and semi-flexible pavements.

[0194] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned implementation modes, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned implementation modes can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the implementation modes of the present invention.

Claims

1. A method for preparing a direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier, characterized in that: The raw materials of the direct-cast fast-melting high-viscosity elastic anti-fatigue asphalt modifier are proportioned as follows by mass: 40-60 parts of elastomer, 15-30 parts of blocked isocyanate and blocked polyurethane prepolymer, 10-20 parts of plasticizer and 10-20 parts of low-grade asphalt; The elastomer is a linear SBS, a star-shaped SBS and a styrene-butadiene rubber in a mass ratio of 2:2:1; the blocked isocyanate and the blocked polyurethane prepolymer include a phenol blocked isocyanate and a phenol blocked polyurethane prepolymer in a mass ratio of 1:2-1:1; the blocked isocyanate and the blocked polyurethane prepolymer can be deblocked to be an isocyanate and an isocyanate-terminated polyurethane prepolymer at 160-180°C; the isocyanate in the phenol blocked isocyanate is at least two of 4,4-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate and isophorone diisocyanate; the polyurethane prepolymer in the phenol blocked polyurethane prepolymer is prepared by reacting polymethylene polyphenyl polyisocyanate with a polyether polyol; and the isocyanate content of the polyurethane prepolymer is controlled to be 10-25 wt%, the plasticizer is a mixture of aromatic oil and dioctyl phthalate in a mass ratio of 3-5:1, the low-grade asphalt is asphalt with a needle penetration of less than 30, The preparation method steps are as follows: Step 1, reacting an excess of polymethylene polyphenyl polyisocyanate with a polyether polyol to obtain an isocyanate-terminated polyurethane prepolymer; Step 2: reacting isocyanate with phenol under the action of a catalyst to obtain blocked isocyanate; reacting the product of step 1 with phenol under the action of a catalyst to obtain a blocked polyurethane prepolymer; Step 3, mixing the blocked isocyanate and the blocked polyurethane prepolymer with the plasticizer, the elastomer and the low-grade asphalt in an open internal mixer; Step 4: Add the mixture prepared in step 3 into the feeding port of the twin-screw extruder by forced feeding, and perform melt blending and granulation at a temperature range of 80-110° C. to obtain a direct-throw fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

2. The method for preparing a direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier according to claim 1, characterized in that: The asphalt is at least one of rock asphalt, lake asphalt, hard asphalt and anti-rutting masterbatch.

3. The method for preparing a direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier according to claim 1, characterized in that: Here are the steps: Step 1, dehydrating the polyether polyol at 120° C. under nitrogen conditions, adding polymethylene polyphenyl polyisocyanate dropwise to the dehydrated polyether polyol at a ratio of n(NCO):n(OH) of 5:1-20:1, and reacting at 60-90° C. under nitrogen conditions to obtain an isocyanate-terminated polyurethane prepolymer; Step 2: adding phenol to isocyanate at a ratio of n(NCO):n(OH) of 1:1.05-1:1.1, adding 0.3-0.6 wt% of dibutyltin dilaurate catalyst, reacting at 50-90°C under nitrogen until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked isocyanate; adding phenol to the product of step 1 at a ratio of n(NCO):n(OH) of 1:1.05-1:1.1, adding 0.3-0.6 wt% of dibutyltin dilaurate catalyst, reacting at 50-90°C under nitrogen until the residual isocyanate content of the synthesized product is less than 0.1 wt%, thereby obtaining a blocked polyurethane prepolymer; Step 3: Mix the blocked isocyanate and blocked polyurethane prepolymer produced in step 2 with the plasticizer, elastomer and low-grade asphalt in an open internal mixer according to the mass ratio for 3-6 minutes; Step 4: Add the mixture prepared in step 3 into the feeding port of the twin-screw extruder through a forced feeding system, and perform melt blending and granulation at a temperature range of 80-110° C. to obtain a direct-throw fast-melting high-viscosity elastic anti-fatigue asphalt modifier.

4. The use of the direct-cast fast-melting high-viscoelastic anti-fatigue asphalt modifier according to claim 1 in the preparation of asphalt mixture is characterized in that: The specific steps are as follows: directly add 0.25-0.55 wt% of the direct-throw fast-melting high-viscoelastic anti-fatigue asphalt modifier to the asphalt mixture into the aggregate at 170-185°C for dry mixing, and then add asphalt and mineral powder to mix. The discharge temperature of the prepared asphalt mixture is 170-180°C.