Bagged modified asphalt and preparation process thereof

Abstract

The invention discloses bagged modified asphalt and a preparation process thereof, and relates to the technical field of asphalt, and the preparation process comprises the following steps: adding alkali-extracted corn stalk lignin and modified attapulgite into a reaction container, uniformly mixing, adding maleic anhydride, and heating for reaction to obtain a compound additive; adding the methyl ethyl ketoxime blocked polyurethane prepolymer and the hydrogenated styrene-isoprene-styrene block copolymer into a reaction container, and stirring at room temperature in a nitrogen atmosphere to obtain a copolymerized modified polyurethane prepolymer; the preparation method comprises the following steps: adding matrix asphalt into a reaction container, heating, shearing and stirring uniformly, adding a compound additive, heating, shearing and stirring, cooling, adding a copolymerized modified polyurethane prepolymer and 4, 4 '-diaminodiphenyl disulfide, preserving heat, shearing and stirring to obtain modified asphalt; and cooling the modified asphalt, injecting into a packaging bag, sealing, and cooling to room temperature to obtain the bagged modified asphalt.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of asphalt, in particular to a bagged modified asphalt and a preparation process thereof. BACKGROUND

[0002] As the core cementitious material in the construction of transportation infrastructure, asphalt is widely used in the engineering fields of highway pavement, airport runway, municipal road, etc., and its performance directly determines the durability, safety and service life of transportation engineering. With the continuous improvement of transportation network and the challenges of extreme weather conditions (such as high-temperature exposure in summer and severe cold and freezing in winter) and the continuous increase of heavy traffic volume, the traditional base asphalt has been difficult to meet the requirements of the comprehensive performance of the material for engineering - rutting, etc. diseases easily occur under high-temperature environment, cracking and peeling easily occur under low-temperature condition, and road damage caused by fatigue aging also occurs after long-term service, which not only increases the maintenance cost, but also affects the traffic efficiency.

[0003] To solve the above problems, the industry generally uses modified asphalt technology, which introduces high molecular polymer, inorganic filler, biomass material and other modified components into base asphalt to control the microstructure and macro performance of asphalt. The current mainstream modified asphalt types include styrene-butadiene-styrene block copolymer (SBS) modified asphalt, polyurethane (PU) modified asphalt, etc. Among them, SBS modified asphalt is widely used in improving the low-temperature crack resistance of asphalt due to its good elastic recovery capacity, but this type of modified asphalt has obvious shortcomings: the compatibility of SBS and base asphalt is poor, and phase separation easily occurs during long-term storage, which requires high shear equipment to enhance the mixing effect, and the construction temperature is usually as high as 160-180℃, which is high in energy consumption and easy to produce harmful volatile substances; at the same time, the high-temperature rutting resistance of SBS modified asphalt is limited, and permanent deformation still easily occurs in heavy traffic sections.

[0004] Polyurethane modified asphalt constructs a three-dimensional network structure through cross-linking reaction and performs better in high-temperature stability and mechanical strength, but its core component isocyanate group (-NCO) has strong chemical activity, which easily reacts with water vapor in the air and hydroxyl group (-OH) in asphalt, resulting in premature curing of the prepolymer, making it difficult to achieve long-term storage at room temperature, and usually the components need to be mixed on site, which not only increases the operation complexity, but also easily affects the modification effect due to uneven mixing. In addition, although the single polyurethane cross-linking system can improve the rigidity, it may also increase the brittleness of asphalt and increase the risk of low-temperature fracture, making it difficult to balance the performance of "high-temperature deformation resistance-low-temperature crack resistance".

[0005] In addition to high molecular polymers, inorganic fillers (such as attapulgite, montmorillonite, etc.) are also often used for asphalt modification to improve material rigidity and aging resistance through "nanofilling effect". However, such inorganic fillers have strong surface polarity, poor compatibility with non-polar asphalt matrix, and easy agglomeration, which not only cannot fully play the role of reinforcement, but also may destroy the continuity of asphalt, leading to a decrease in low-temperature ductility and a damage to toughness. In recent years, biomass materials (such as lignin) have gradually become a research hotspot in the field of modified asphalt due to their green and environmentally friendly advantages and wide sources. The hydroxyl groups in lignin can form hydrogen bonds with asphalt components, but the improvement effect on high-temperature performance of asphalt is limited when lignin is used alone, and the synergistic action mechanism with inorganic fillers and high molecular polymers is not clear, making it difficult to form a stable "reinforcement-toughening" system.

[0006] From the perspective of engineering application, the existing packaging and storage methods of modified asphalt also have limitations: most products are in the form of barrels or bulk, which are easy to be contaminated during transportation and need to be maintained at a certain temperature to prevent caking, increasing the logistics cost; some bagged modified asphalt products are prone to hardening and delamination after cooling due to unreasonable formula design, and need to be melted at high temperature for a long time during use, which not only reduces the construction efficiency, but also may cause local overheating and aging of asphalt.

[0007] In summary, the current modified asphalt technology still faces multiple challenges: first, the performance balance is insufficient, making it difficult to meet the engineering requirements of high-temperature rut resistance, low-temperature crack resistance, and long-term fatigue resistance; second, the storage stability is poor, and the performance may be degraded due to environmental factors; third, the construction convenience is low, relying on complex equipment or on-site blending; fourth, the greenness needs to be improved, and some modified components (such as specific chemical additives) have environmental risks, and the efficient utilization technology of biomass materials is not mature. Therefore, developing a modified asphalt with balanced performance, stable storage, convenient construction, and in line with the trend of green building materials has become a key demand for promoting the high-quality development of transportation infrastructure. SUMMARY

[0008] The purpose of the present application is to provide a bagged modified asphalt and a preparation process thereof to solve the problems in the prior art.

[0009] To achieve the above-mentioned purpose, the present application provides the following technical solutions: A preparation process of a bagged modified asphalt, comprising the following steps: S1: vacuum dehydrating polypropylene glycol after adding poly-methylene polyphenyl polyisocyanate into a reaction container, heating to 70-75℃ for 15-30min, adding methyl ethyl ketone oxime, stirring uniformly, and keeping warm for 18-24h to obtain a methyl ethyl ketone oxime blocked polyurethane prepolymer; Further, in the preparation process of the methyl ethyl ketone oxime blocked polyurethane prepolymer, the mass ratio of the polymethylene polyphenyl polyisocyanate to the polypropylene glycol is (9-10):(5-5.5); the methyl ethyl ketone oxime is added in an amount of 5.6-5.8% of the total mass of the polymethylene polyphenyl polyisocyanate and the polypropylene glycol; Further, the polymethylene polyphenyl polyisocyanate has a specification of an isocyanate group content of 31.06% and a diisocyanate group: triisocyanate group ratio of 7:3; Further, the polypropylene glycol has a specification of a molecular weight of 400; S2: The alkali-extracted corn stalk lignin and the modified attapulgite are added into a reaction container, uniformly mixed, maleic anhydride is added, heated to 110-115°C and reacted for 30-35 min to obtain a composite additive; Further, in the preparation process of the composite additive, the mass ratio of the alkali-extracted corn stalk lignin to the modified attapulgite is (3-5):(1-2); the maleic anhydride is added in an amount of 2-3% of the total mass of the alkali-extracted corn stalk lignin and the modified attapulgite; Further, the alkali-extracted corn stalk lignin has a specification of a hydroxyl group content of 8-10 mmol / g; Further, the preparation method of the modified attapulgite comprises the following steps: The attapulgite is soaked in 4-5 mol / L sulfuric acid, heated to 75-78°C and reacted for 4-5 h, centrifuged, the product is washed to neutral to obtain activated attapulgite; the activated attapulgite is soaked in 1-1.5 mol / L sodium chloride solution, washed, dried and then placed in an aqueous solution of quaternary ammonium salt cationic surfactant, ultrasonically treated, washed and dried to obtain the modified attapulgite; Further, in the modified attapulgite, the concentration of the aqueous solution of quaternary ammonium salt cationic surfactant is 0.036-0.048 mol / L; Further, the attapulgite has a specification of a particle size of 40-50 μm; Further, the quaternary ammonium salt cationic surfactant includes any one of cetyltrimethylammonium bromide and tetradecyltrimethylammonium chloride; S3: The methyl ethyl ketone oxime blocked polyurethane prepolymer and the hydrogenated styrene-isoprene-styrene block copolymer are added into a reaction container, stirred at room temperature for 20-25 min under a nitrogen atmosphere to obtain a copolymer modified polyurethane prepolymer; Further, in the preparation process of the copolymer modified polyurethane prepolymer, the mass ratio of the methyl ethyl ketone oxime blocked polyurethane prepolymer to the hydrogenated styrene-isoprene-styrene block copolymer is 1:(1.25-1.5); S4: the base pitch is added into a reaction container, heated to 130-135 DEG C, shearing and stirring uniformly, the composite additive is added, heated to 150-155 DEG C, shearing and stirring for 1-1.5 h, the copolymer modified polyurethane prepolymer and 4,4'-diamino diphenyl disulfide are added at 120-125 DEG C, and shearing and stirring for 2-2.5 h, to obtain modified pitch; Further, the mechanism pitch specification: penetration is 85.2 DEG C; Further, the modified pitch is prepared by the following components in parts by mass: base pitch 90-100 parts, composite additive 4-6 parts, copolymer modified polyurethane prepolymer 5-8 parts, and 4,4'-diamino diphenyl disulfide 0.75-1.2 parts; S5: the modified pitch is cooled to 80-90 DEG C and injected into a packaging bag, sealed and cooled to room temperature to obtain a bagged modified pitch.

[0010] Compared with the prior art, the beneficial effects of the present application are: 1, in the present application, methyl ethyl ketone oxime reacts with isocyanate groups to form a C-N-O weak bond, which closes the activity of -NCO and prevents it from reacting with water vapor in the air or -OH in pitch, ensuring the storage stability at room temperature and greatly improving the convenience of construction production; at 120-125 DEG C, the C-N-O weak bond breaks, releasing free -NCO, which reacts with the active sites of the isoprene segment of hydrogenated styrene-isoprene-styrene block copolymer, -NH2 of 4,4'-diamino diphenyl disulfide and -OH in pitch to form urethane bonds and construct a three-dimensional crosslinked network.

[0011] 2, in the present application, the hydroxyl groups of alkali-extracted lignin are adsorbed on the pores and surface of attapulgite, which inhibits the agglomeration of attapulgite and connects attapulgite and pitch matrix through polarity to form a "nano-filling-polar bridging" reinforcing system; the -CO-O-CO- of maleic anhydride reacts with the hydroxyl groups of lignin and the Si-OH of attapulgite to form ester groups, eliminating the interfacial tension between the two, improving the dispersion uniformity of the composite additive in pitch and avoiding the increase in brittleness caused by "filling agglomeration".

[0012] 3、The application can wrap the methyl ethyl ketoxime blocked polyurethane prepolymer particles by the segment of hydrogenated styrene-isoprene-styrene block copolymer, avoid the methyl ethyl ketoxime blocked polyurethane prepolymer from agglomerating in the asphalt at room temperature, and the crosslinked network formed after the methyl ethyl ketoxime blocked polyurethane prepolymer is unblocked can provide 'rigid support' for the hydrogenated styrene-isoprene-styrene block copolymer, and the elastic soft segment of the hydrogenated styrene-isoprene-styrene block can provide 'flexible cushion' for the crosslinked network, and the IPN structure formed by the two can improve the elastic recovery rate of the modified asphalt, and meanwhile, the brittle fracture can be avoided to improve the elongation at break.

[0013] 4、The application can embed the needle-shaped particles of the modified attapulgite into the IPN network of the copolymer modified polyurethane prepolymer to serve as 'nano reinforcing points', improve the anti-deformation ability of the network, and form hydrogen bonds between the hydroxyl groups of the alkali-extracted lignin and the urethane groups in the IPN network to reduce phase separation, so that the storage stability of the modified asphalt is further improved.

[0014] 5、The application can form a 'dynamic stress adjustment system' by the disulfide bond of 4,4'-diaminodiphenyl disulfide and the elastic soft segment of the hydrogenated styrene-isoprene-styrene block copolymer, so that the disulfide bond can be reorganized to relieve local stress when stressed, and the soft segment can absorb energy through chain segment motion.

[0015] 6、The application can realize the storage stabilization, performance equalization and construction convenience of the modified asphalt through the synergistic design of 'composite additive enhancement + copolymer prepolymer crosslinking + 4,4'-diaminodiphenyl disulfide chain extension' and precise process control. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the application will be described below in a clear and complete manner. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0017] In the following embodiments, the poly-methylene-polyphenyl-polyisocyanate is CAS: 9016-87-9. The preparation method of the modified attapulgite includes the following steps: The attapulgite is soaked in 4 mol / L sulfuric acid and heated to 75℃ for 4h, centrifuged, and the product is washed to neutral to obtain activated attapulgite; 10g of the activated attapulgite is soaked in 1 mol / L sodium chloride solution, washed, dried, and then placed in 0.036 mol / L cetyltrimethylammonium bromide aqueous solution, ultrasonically treated, washed, and dried to obtain the modified attapulgite.

[0018] Embodiment 1: A preparation process of a bagged modified asphalt, comprising the following steps: S1: 9g of polymethylene polyphenyl polyisocyanate, 5g of polypropylene glycol after vacuum dehydration is added into a reaction container, heated to 70 DEG C for reaction for 15min, 0.784g of methyl ethyl ketone oxime is added, stirred uniformly, and incubated for reaction for 18h to obtain a methyl ethyl ketone oxime blocked polyurethane prepolymer; S2: 3g of alkali-extracted corn stalk lignin, 1g of modified attapulgite is added into a reaction container, mixed uniformly, 0.08g of maleic anhydride is added, heated to 110 DEG C for reaction for 30min to obtain a composite additive; S3: 1g of the methyl ethyl ketone oxime blocked polyurethane prepolymer, 1.25g of hydrogenated styrene-isoprene-styrene block copolymer is added into a reaction container, stirred at room temperature for 20min under a nitrogen atmosphere to obtain a copolymer modified polyurethane prepolymer; S4: 100 parts of base asphalt is added into a reaction container, heated to 130 DEG C, and sheared and stirred uniformly, 4 parts of the composite additive is added, heated to 150 DEG C, and sheared and stirred for 1h, cooled to 120 DEG C, 5 parts of the copolymer modified polyurethane prepolymer, 0.75 parts of 4,4'-diaminodiphenyl disulfide is added, and sheared and stirred for 2h to obtain a modified asphalt; S5: The modified asphalt is cooled to 80-90 DEG C, injected into a packaging bag, sealed, and cooled to room temperature to obtain a bagged modified asphalt.

[0019] Embodiment 2: A preparation process of a bagged modified asphalt, comprising the following steps: S1: 9g of polymethylene polyphenyl polyisocyanate, 5g of polypropylene glycol after vacuum dehydration is added into a reaction container, heated to 70 DEG C for reaction for 15min, 0.784g of methyl ethyl ketone oxime is added, stirred uniformly, and incubated for reaction for 18h to obtain a methyl ethyl ketone oxime blocked polyurethane prepolymer; S2: 3g of alkali-extracted corn stalk lignin, 1g of modified attapulgite is added into a reaction container, mixed uniformly, 0.08g of maleic anhydride is added, heated to 110 DEG C for reaction for 30min to obtain a composite additive; S3: 1g of the methyl ethyl ketone oxime blocked polyurethane prepolymer, 1.25g of hydrogenated styrene-isoprene-styrene block copolymer is added into a reaction container, stirred at room temperature for 20min under a nitrogen atmosphere to obtain a copolymer modified polyurethane prepolymer; S4: 100 parts of base asphalt is added into a reaction container, heated to 130 DEG C, and sheared and stirred uniformly, 5 parts of the composite additive is added, heated to 150 DEG C, and sheared and stirred for 1h, cooled to 120 DEG C, 6 parts of the copolymer modified polyurethane prepolymer, 0.9 parts of 4,4'-diaminodiphenyl disulfide is added, and sheared and stirred for 2h to obtain a modified asphalt; S5: The modified asphalt is cooled to 80-90 DEG C, injected into a packaging bag, sealed, and cooled to room temperature to obtain a bagged modified asphalt.

[0020] Example 3: A preparation process of a bagged modified asphalt, comprising the following steps: S1: 9 g of polymethylene polyphenyl polyisocyanate, 5 g of polypropylene glycol after vacuum dehydration is added to a reaction container, heated to 70 DEG C for 15 min, 0.784 g of methyl ethyl ketone oxime is added, stirred uniformly, and incubated for 18 h to obtain a methyl ethyl ketone oxime blocked polyurethane prepolymer; S2: 3 g of alkali-extracted corn stalk lignin, 1 g of modified attapulgite is added to the reaction container, mixed uniformly, 0.08 g of maleic anhydride is added, heated to 110 DEG C for 30 min to obtain a composite additive; S3: 1 g of methyl ethyl ketone oxime blocked polyurethane prepolymer, 1.25 g of hydrogenated styrene-isoprene-styrene block copolymer is added to the reaction container, stirred at room temperature for 20 min under nitrogen atmosphere to obtain a copolymer modified polyurethane prepolymer; S4: 100 parts of base asphalt is added to the reaction container, heated to 130 DEG C, sheared and stirred uniformly, 6 parts of the composite additive is added, heated to 150 DEG C, sheared and stirred for 1 h, cooled to 120 DEG C, 8 parts of the copolymer modified polyurethane prepolymer, 1.2 parts of 4,4'-diamino diphenyl disulfide is added, and sheared and stirred for 2 h to obtain a modified asphalt; S5: The modified asphalt is cooled to 80-90 DEG C and injected into a packaging bag, sealed and cooled to room temperature to obtain a bagged modified asphalt.

[0021] Comparative Example 1: A preparation process of a bagged modified asphalt, comprising the following steps: S1: 9 g of polymethylene polyphenyl polyisocyanate, 5 g of polypropylene glycol after vacuum dehydration is added to a reaction container, heated to 70 DEG C for 15 min, 0.784 g of methyl ethyl ketone oxime is added, stirred uniformly, and incubated for 18 h to obtain a methyl ethyl ketone oxime blocked polyurethane prepolymer; S2: 1 g of methyl ethyl ketone oxime blocked polyurethane prepolymer, 1.25 g of hydrogenated styrene-isoprene-styrene block copolymer is added to the reaction container, stirred at room temperature for 20 min under nitrogen atmosphere to obtain a copolymer modified polyurethane prepolymer; S3: 100 parts of base asphalt is added to the reaction container, heated to 130 DEG C, sheared and stirred uniformly, cooled to 120 DEG C, 5 parts of the copolymer modified polyurethane prepolymer, 0.75 parts of 4,4'-diamino diphenyl disulfide is added, and sheared and stirred for 2 h to obtain a modified asphalt; S4: The modified asphalt is cooled to 80-90 DEG C and injected into a packaging bag, sealed and cooled to room temperature to obtain a bagged modified asphalt.

[0022] Comparative Example 2: A preparation process of a bagged modified asphalt, comprising the following steps: S1: 9 g of polymethylene polyphenyl polyisocyanate, 5 g of polypropylene glycol after vacuum dehydration were added to a reaction container, heated to 70°C for 15 min, 0.784 g of methyl ethyl ketone oxime was added, stirred uniformly, and incubated for 18 h to obtain a methyl ethyl ketone oxime blocked polyurethane prepolymer; S2: 3 g of alkali-extracted corn stalk lignin, 1 g of modified attapulgite were added to a reaction container, mixed uniformly, 0.08 g of maleic anhydride was added, heated to 110°C for 30 min to obtain a composite additive; S3: 100 parts of base asphalt were added to a reaction container, heated to 130°C, and sheared and stirred uniformly, 4 parts of the composite additive were added, heated to 150°C, and sheared and stirred for 1 h, cooled to 120°C, 5 parts of the methyl ethyl ketone oxime blocked polyurethane prepolymer, 0.75 parts of 4,4'-diamino diphenyl disulfide were added, and incubated and sheared and stirred for 2 h to obtain a modified asphalt; S4: The modified asphalt was cooled to 80-90°C and injected into a packaging bag, sealed, and cooled to room temperature to obtain a bagged modified asphalt.

[0023] Comparative Example 3: A preparation process of a bagged modified asphalt, comprising the following steps: S1: 9 g of polymethylene polyphenyl polyisocyanate, 5 g of polypropylene glycol after vacuum dehydration were added to a reaction container, heated to 70°C for 15 min, 0.784 g of methyl ethyl ketone oxime was added, stirred uniformly, and incubated for 18 h to obtain a methyl ethyl ketone oxime blocked polyurethane prepolymer; S2: 3 g of alkali-extracted corn stalk lignin, 1 g of modified attapulgite were added to a reaction container, mixed uniformly, 0.08 g of maleic anhydride was added, heated to 110°C for 30 min to obtain a composite additive; S3: 1 g of the methyl ethyl ketone oxime blocked polyurethane prepolymer, 1.25 g of hydrogenated styrene-isoprene-styrene block copolymer were added to a reaction container, stirred at room temperature for 20 min under a nitrogen atmosphere to obtain a copolymer modified polyurethane prepolymer; S4: 100 parts of base asphalt were added to a reaction container, heated to 130°C, and sheared and stirred uniformly, 4 parts of the composite additive were added, heated to 150°C, and sheared and stirred for 1 h, cooled to 120°C, 5 parts of the copolymer modified polyurethane prepolymer, 0.75 parts of 4,4'-methylene bis(2-chloroaniline) were added, and incubated and sheared and stirred for 2 h to obtain a modified asphalt; S5: The modified asphalt was cooled to 80-90°C and injected into a packaging bag, sealed, and cooled to room temperature to obtain a bagged modified asphalt.

[0024] Comparative Example 4: A commercially available SBS modified asphalt; specification: 70#, SBS content is 4.5%.

[0025] Comparative Example 5: Commercial PU modified asphalt; Specification: PU prepolymer content is 6%.

[0026] Experiment: High temperature rutting resistance: G' at 64℃, 10 rad / s under dynamic shear rheometer according to ASTM D7175 * / sin delta (the bigger, the stronger the rutting resistance); Low temperature cracking resistance: Creep stiffness S (the smaller, the better) and creep rate m (the bigger, the better) at -18℃ under bending beam rheometer according to ASTM D6648; General high and low temperature indicators: 5℃ ductility The above experimental samples are selected from Examples 1-3, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5; the experimental results are shown in Table 1 below.

[0027] Static mechanical properties: 5℃ tensile strength and elastic recovery rate (measured after 25℃ storage for 10 min) by force elongation instrument; Fatigue resistance: linear amplitude sweep test, 19℃, 8mm parallel plate, measured fatigue cycle number Nf at 5% strain (the more, the better); Hardness: cone penetration test; The above experimental samples are selected from Examples 1-3, Comparative Example 1, Comparative Example 4, and Comparative Example 5; the experimental results are shown in Table 2 below.

[0028] Table 1 Performance test data table Conclusion: Comparative Example 1 has weak high temperature deformation resistance and large low temperature stiffness without composite aid; Comparative Example 2 has poor high temperature rutting resistance due to incomplete IPN network of hydrogenated styrene-isoprene-styrene block copolymer; Comparative Example 3 has poor low temperature stress relaxation due to insufficient chain extension of disulfide bond; and Comparative Example 4 has weak low temperature cracking resistance of traditional SBS.

[0029] Table 2 Performance test data table Conclusion: Comparative Example 1 has poor fatigue resistance due to insufficient rigidity without composite aid; Comparative Example 4 has poor elastic recovery of commercial SBS modified asphalt; and Comparative Example 5 has weak fatigue resistance of commercial PU modified asphalt.

[0030] It is apparent for those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and that the present application can be implemented in other particular forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalents of the claims are therefore intended to be embraced therein.

Claims

1. A process for the preparation of a bagged modified bitumen, characterized in that: It comprises the following steps: S1: the alkali extraction of corn stalk lignin, modified attapulgite is added to the reaction container, mixed uniformly, maleic anhydride is added, heated to 110-115℃ for 30-35min, the composite additive is obtained; S2: methyl ethyl ketone oxime blocked polyurethane prepolymer, hydrogenated styrene-isoprene-styrene block copolymer is added to the reaction container, nitrogen atmosphere, room temperature stirring, copolymer modified polyurethane prepolymer is obtained; S3: the matrix asphalt is added to the reaction container, heated to 130-135℃, shear stirring, the composite additive is added, heated to 150-155℃, shear stirring 1-1.5h, the temperature is reduced to 120-125℃, copolymer modified polyurethane prepolymer, 4,4'-diamino diphenyl disulfide is added, shear stirring 2-2.5h, modified asphalt is obtained; S4: the modified asphalt is cooled to 80-90℃ and injected into the packaging bag, sealed and cooled to room temperature, bagged modified asphalt is obtained.

2. The process for preparing a bagged modified bitumen according to claim 1, characterized in that: The preparation method of the methyl ethyl ketone oxime blocked polyurethane prepolymer comprises the following steps: after vacuum dehydration of the polypropylene glycol, the polypropylene glycol is added to the reaction container, heated to 70-75℃ for 15-30min, methyl ethyl ketone oxime is added, stirred uniformly, and the reaction is carried out for 18-24h to obtain the methyl ethyl ketone oxime blocked polyurethane prepolymer.

3. The process for preparing a bagged modified bitumen according to claim 2, characterized in that: In the preparation process of the methyl ethyl ketone oxime blocked polyurethane prepolymer, the mass ratio of the polypropylene glycol to the polypropylene glycol is (9-10):(5-5.5); the amount of methyl ethyl ketone oxime added is 5.6-5.8% of the total mass of the polypropylene glycol and the polypropylene glycol.

4. The process for preparing a bagged modified bitumen as claimed in claim 1, wherein: In the preparation process of the composite additive, the mass ratio of the alkali extraction of corn stalk lignin to the modified attapulgite is (3-5):(1-2); the amount of maleic anhydride added is 2-3% of the total mass of the alkali extraction of corn stalk lignin and the modified attapulgite.

5. The process for preparing a bagged modified bitumen as claimed in claim 1, wherein: The preparation method of the modified attapulgite comprises the following steps: The attapulgite is soaked in 4-5mol / L sulfuric acid, heated to 75-78℃ for 4-5h, centrifuged, and the product is washed to neutral to obtain activated attapulgite; the activated attapulgite is soaked in 1-1.5mol / L sodium chloride solution, washed, dried, and then placed in an aqueous solution of quaternary ammonium salt cationic surfactant, ultrasonic treated, washed, and dried to obtain modified attapulgite.

6. The process for preparing a bagged modified bitumen according to claim 5, characterized in that: In the modified attapulgite, the concentration of the aqueous solution of quaternary ammonium salt cationic surfactant is 0.036-0.048mol / L; The quaternary ammonium salt cationic surfactant includes any one of cetyltrimethylammonium bromide and tetradecyltrimethylammonium chloride.

7. The process for preparing a bagged modified bitumen as claimed in claim 1, wherein: In the preparation process of the copolymer modified polyurethane prepolymer, the mass ratio of the methyl ethyl ketone oxime blocked polyurethane prepolymer to the hydrogenated styrene-isoprene-styrene block copolymer is 1:(1.25-1.5).

8. The process for preparing a bagged modified bitumen as claimed in claim 1, wherein: In the preparation process of the modified asphalt, the proportions of the components are as follows in terms of mass parts: matrix asphalt 90-100 parts, composite additive 4-6 parts, copolymer modified polyurethane prepolymer 5-8 parts, and 4,4'-diamino diphenyl disulfide 0.75-1.2 parts.

9. A bagged modified bitumen prepared according to the process of any one of claims 1 to 8.

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