Compound polymer modifiers, modified asphalt containing them, and their preparation methods

Abstract

This disclosure provides a compound polymer modifier, modified asphalt containing the same, and a method for preparing the same. The compound polymer modifier includes a polymer-modified matrix and a functional layer coated on the surface of the polymer-modified matrix. The functional layer includes an inorganic material and an active component encapsulated within the inorganic material, wherein the active component has anti-aging properties. The modified asphalt comprises a base asphalt and the aforementioned compound polymer modifier dispersed therein. The preparation method includes preparing anti-aging microcapsules by liquid-phase deposition, and then coating them onto the surface of the polymer-modified matrix by dry blending or solution blending. This disclosure significantly inhibits oxidative crusting and phase separation of modified asphalt during high-temperature storage through the synergistic effect of the physical barrier of the inorganic wall material and the slow-release effect of the active component, reducing the difference in the segregation softening point, improving interfacial compatibility, and enhancing storage stability. Furthermore, the process is simple and easy for industrial application.

Description

Technical Field

[0001] This disclosure relates to the field of functional composite materials technology, and more specifically to compounded polymer modifiers, modified bitumen containing the same, and methods for their preparation. Background Technology

[0002] With the rapid development of highway construction and transportation, asphalt has become an important road construction material. Polymer (polystyrene-butadiene-styrene copolymer) modified asphalt is widely used in modified asphalt due to its excellent low-temperature performance and anti-aging properties. However, polymer-modified asphalt is easily affected by oxygen during high-temperature storage or long-term transportation, resulting in oxidation reactions, leading to a series of problems such as asphalt oxidation, skin formation, and decreased tensile strength, which seriously affect the engineering application effect and safety of asphalt. Summary of the Invention

[0003] The inventors unexpectedly discovered that by encapsulating an active component with anti-aging properties within an inorganic material to form a functional layer, and then coating this functional layer onto the surface of a polymer-modified matrix, the resulting compound polymer modifier, when added to the base asphalt, not only significantly reduces the oxygen permeability in the asphalt system by utilizing the inorganic material as a physical barrier, but also allows the encapsulated active component to achieve long-term sustained release during high-temperature storage, continuously inhibiting free radical chain reactions. Even more unexpectedly, the core-shell structured compound polymer modifier also significantly improves the interfacial compatibility between the polymer-modified matrix and the base asphalt, substantially reducing the difference in the segregation softening point. This invention was derived based on these unexpected discoveries.

[0004] In one aspect of this disclosure, a compound polymer modifier is provided, comprising:

[0005] A polymer-modified matrix; and a functional layer coated on the surface of the polymer-modified matrix; the functional layer comprising an inorganic material and an active component encapsulated within the inorganic material, wherein the active component has an anti-aging function.

[0006] In another aspect of this disclosure, a modified bitumen comprising:

[0007] Base bitumen; and

[0008] The compound polymer modifier according to the above aspects is dispersed in the matrix bitumen.

[0009] In another aspect of this disclosure, a method for preparing the above-described compounded polymer modifier is provided, comprising:

[0010] (1) Preparation of anti-aging microcapsules: The active component is dissolved in an organic solvent, an inorganic material precursor is added to it, and the inorganic material is generated on the surface of the active component by liquid phase deposition under the action of a catalyst to obtain anti-aging microcapsules;

[0011] (2) Coating treatment: The polymer-modified matrix is ​​mixed with the anti-aging microcapsules, and the anti-aging microcapsules are coated on the surface of the polymer-modified matrix by mechanical force or solvent binding.

[0012] This disclosure offers at least one of the following beneficial effects: By encapsulating the active component in an inorganic material to form a functional layer and coating it on the surface of the polymer-modified matrix, a dual anti-aging mechanism is achieved through the synergistic effect of the physical barrier of the inorganic wall material and the chemical slow-release of the active component. This effectively inhibits oxidative crusting and phase separation during high-temperature storage of modified asphalt, reducing the difference in the segregation softening point. Simultaneously, the surface treatment of the outer microcapsule wall material improves the interfacial compatibility between the polymer and asphalt, significantly improving the dispersion stability of the polymer modifier in the asphalt system. This not only avoids phase separation during high-temperature storage but also stabilizes the colloidal structure of the asphalt. Furthermore, outstanding effects can be achieved within a narrow addition range without the need for additional dispersants or complex processes. Moreover, the microcapsules are prepared using dry blending or liquid-phase deposition methods, resulting in less microcapsule aggregation, stable product quality, simple process, and ease of industrial application. Detailed Implementation

[0013] This disclosure will be described in more detail below to aid in understanding it.

[0014] It should be understood that the terms or words used in this specification and the appended claims should not be construed as limited to their general or dictionary meanings, but rather interpreted based on their meanings and concepts corresponding to the technical aspects of this disclosure, on the basis of the principle that the inventors are allowed to define terms appropriately for the purpose of best illustration.

[0015] It should be further understood that, unless otherwise expressly stated, when used in the specification, "comprising" or "including" indicates the presence of the said element and does not exclude the presence or addition of one or more other elements.

[0016] As used herein, a range is used as a shorthand to describe the individual values ​​within the range and each value. Any value within the range can be chosen as an endpoint of the range. Thus, the ranges 1 to 5 specifically include 1, 2, 3, 4, and 5, as well as subranges such as 2 to 5, 3 to 5, 2 to 3, 2 to 4, 1 to 4, etc.

[0017] As used in this article, "selected from" means selecting one, two or more candidates.

[0018] As used herein, the term "compound polymer modifier" refers to composite particles consisting of a polymer-modified matrix and a functional layer coated on its surface.

[0019] As used herein, the term "functional layer" refers to a layered structure located outside a polymer-modified matrix, containing inorganic materials and active components encapsulated therein.

[0020] As used herein, the term "inorganic material" refers to inorganic substances used as microcapsule wall materials, including but not limited to silicon dioxide, modified alumina, and mixtures thereof.

[0021] As used herein, the term "active component" refers to a chemical additive that is encapsulated within an inorganic material and has anti-aging properties, including but not limited to hindered phenolic antioxidants and phosphite antioxidants.

[0022] As used in this article, the term "anti-aging function" refers to the ability to inhibit or delay the aging, degradation, cross-linking, or discoloration of materials under the influence of environmental factors such as heat, oxygen, and light.

[0023] As used in this article, the term "anti-aging microcapsule" refers to core-shell particles with inorganic materials as the wall material and anti-aging active components as the core material.

[0024] As used in this article, the term "wall material" refers to the inorganic material layer that constitutes the outer shell of the microcapsule.

[0025] As used in this article, the term "core material" refers to the internal material encapsulated by the wall material.

[0026] As used in this article, the term "core-shell structure" refers to a composite structure consisting of a core (polymer-modified matrix) and an outer shell (functional layer or anti-aging microcapsule layer).

[0027] As used herein, the term "polymer-modified matrix" refers to the polymeric materials used to modify bitumen, including thermoplastic elastomers, rubbers, and thermoplastic resins.

[0028] As used herein, the term "thermoplastic elastomer" refers to a polymer that is rubber-elastic and thermoplasticizable, including but not limited to styrene-butadiene-styrene block copolymer (SBS).

[0029] As used herein, the term "rubber" refers to polymeric materials with high elasticity and crosslinkability, including but not limited to natural rubber, styrene-butadiene rubber, cis-butadiene rubber, chloroprene rubber, nitrile rubber, and butyl rubber.

[0030] As used herein, the term "thermoplastic resin" refers to a polymeric material that softens when heated, hardens when cooled, and can be repeatedly plasticized, including but not limited to polyethylene, polypropylene, polyvinyl chloride, polystyrene, ethylene-vinyl acetate copolymer, and atactic polypropylene.

[0031] As used herein, the term “hindered phenolic antioxidant” refers to antioxidants containing sterically hindered phenolic structures, such as 2,6-di-tert-butyl-p-cresol (BHT).

[0032] As used herein, the term "phosphite antioxidant" refers to auxiliary antioxidants containing a phosphite structure, such as antioxidant 168.

[0033] As used in this article, the term "inorganic oxide" refers to compounds formed by metals or nonmetals with oxygen, such as silicon dioxide and aluminum oxide.

[0034] As used in this article, the term "inorganic silicate" refers to inorganic compounds containing silicate groups.

[0035] As used herein, the term “nano silica” refers to silica particles with an average particle size in the range of 1 to 200 nanometers.

[0036] As used in this article, the term "modified alumina" refers to alumina whose surface has been chemically treated or doped.

[0037] As used herein, the term "base bitumen" refers to petroleum bitumen used in road or building construction projects, such as 70# road petroleum bitumen.

[0038] As used herein, the term "compatibility agent" refers to a substance that can improve the interfacial compatibility between the polymer-modified matrix and the base bitumen, including but not limited to aromatic oils, naphthenic oils, rubber oils, styrene-butadiene block copolymers, and maleic anhydride grafted polymers.

[0039] As used herein, the term "stabilizer" refers to a substance that can promote the chemical crosslinking or physical stabilization of polymer modifiers with asphalt, including but not limited to sulfur powder, elemental sulfur, and sulfur-containing crosslinking agents.

[0040] As used herein, the term "liquid phase deposition" refers to a method of depositing wall materials on the surface of a core material in a liquid phase system through reactions such as sol-gel or in-situ polymerization.

[0041] As used in this article, the term "mechanical action" refers to the process by which microcapsules are attached to the surface of a polymer matrix through physical means such as stirring, mixing, and grinding.

[0042] As used herein, the term "solvent binding" refers to a method in which microcapsules are embedded in or adhered to the surface of a polymer matrix by means of an organic solvent dissolving or swelling the surface of the matrix.

[0043] In one aspect of this disclosure, a compound polymer modifier is provided, comprising:

[0044] A polymer-modified matrix; and a functional layer coated on the surface of the polymer-modified matrix; the functional layer includes an inorganic material and an active component encapsulated within the inorganic material, wherein the active component has an anti-aging function.

[0045] In some implementations, the functional layer is composed of anti-aging microcapsules, which use inorganic materials as wall materials and active components as core materials.

[0046] In some embodiments, the compounded polymer modifier is particulate and has a core-shell structure, with the polymer-modified matrix forming the core and the functional layer forming the shell. Preferably, the active components in the functional layer are distributed in the form of microcapsules.

[0047] In some embodiments, the mass percentage of the polymer-modified matrix can be 80% to 90% based on the total mass of the compounded polymer modifier. In some embodiments, the mass percentage of the polymer-modified matrix can be 80%, 81%, 82%, 84%, 86%, 88%, 89% to 90% based on the total mass of the compounded polymer modifier. In some embodiments, the mass percentage of the functional layer can be 10% to 20% based on the total mass of the compounded polymer modifier. In some embodiments, the mass percentage of the functional layer can be 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% to 20% based on the total mass of the compounded polymer modifier. In some embodiments, the mass ratio of inorganic material to active component in the functional layer can be 1:1 to 3:1. In some embodiments, the mass ratio of inorganic material to active component in the functional layer can be 1:1, 1.5:1, 2:1, 2.5:1 to 3:1.

[0048] In some embodiments, the polymer-modified matrix is ​​selected from thermoplastic elastomers, rubbers, and thermoplastic resins. In some embodiments, the thermoplastic elastomer is selected from styrene-butadiene-styrene block copolymers (SBS), styrene-isoprene-styrene block copolymers (SIS), and styrene-ethylene / butene-styrene block copolymers (SEBS). In some embodiments, the rubber is selected from styrene-butadiene rubber (SBR), natural rubber (NR), chloroprene rubber (CR), and recycled rubber powder. In some embodiments, the thermoplastic resin is selected from polyethylene (PE), polypropylene (PP), and ethylene-vinyl acetate copolymer (EVA).

[0049] In some embodiments, the active ingredient is selected from hindered phenolic antioxidants and phosphite antioxidants. In some embodiments, the active ingredient may be 2,6-di-tert-butyl-p-cresol (BHT). In some embodiments, the inorganic material is selected from inorganic oxides and inorganic silicates. In some embodiments, the inorganic material is selected from silica and modified alumina. In some embodiments, the inorganic material is selected from nano-silica and modified alumina. Preferably, the silica may be nano-silica. In some embodiments, the average particle size of the inorganic material may be 50 to 200 nm. In some embodiments, the average particle size of the inorganic material may be 50, 70, 90, 110, 130, 150, 170, 190 to 200 nm. In some embodiments, for example, the average particle size of silica or modified alumina is 50 to 200 nm.

[0050] In some implementations, the inorganic material exhibits a thermal weight loss of less than 1% at 200°C. The inorganic material demonstrates excellent thermal stability, maintaining structural integrity during high-temperature storage and processing of asphalt, ensuring the continued effectiveness of the physical barrier function.

[0051] In another aspect of this disclosure, a modified bitumen is provided comprising: a base bitumen; and a compound polymer modifier according to the foregoing aspects dispersed in the base bitumen.

[0052] In some embodiments, the content of the compounded polymer modifier is 3 to 20 parts by weight per 100 parts by weight of the base asphalt. In some embodiments, for example, the content of the compounded polymer modifier may be 3, 4, 5, 6, 7, 8, 10 to 12 parts by weight per 100 parts by weight of the base asphalt. In some embodiments, the content of the compounded polymer modifier is preferably 3 to 8 parts by weight per 100 parts by weight of the base asphalt.

[0053] In some embodiments, the modified bitumen may further comprise a compatibilizer. In some embodiments, the compatibilizer is selected from aromatic oils, naphthenic oils, rubber oils, styrene-butadiene block copolymers, and maleic anhydride graft polymers, preferably aromatic oils. In some embodiments, the compatibilizer content may be 0.5 to 12 parts by weight per 100 parts by weight of the base bitumen. In some embodiments, the compatibilizer content may be 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 to 2 parts by weight per 100 parts by weight of the base bitumen.

[0054] In some embodiments, the modified asphalt may further comprise a stabilizer. In some embodiments, the stabilizer is selected from sulfur powder, elemental sulfur, and sulfur-containing crosslinking agents, preferably sulfur powder. In some embodiments, the stabilizer content may be 0.1 to 0.3 parts by weight per 100 parts by weight of base asphalt. In some embodiments, the stabilizer content may be 0.1, 0.12, 0.14, 0.16, 0.18, 0.2, 0.22, 0.24, 0.26, 0.28 to 0.3 parts by weight per 100 parts by weight of base asphalt.

[0055] In some embodiments, based on 100 parts by weight of base bitumen, the modified bitumen comprises: 3 to 8 parts by weight of a compound polymer modifier, 0.5 to 12 parts by weight of a compatibilizer, and 0.1 to 0.3 parts by weight of a stabilizer.

[0056] In some implementation schemes, the base asphalt may be selected from 70# road petroleum asphalt.

[0057] In another aspect of this disclosure, a method for preparing the above-described compound polymer modifier is provided, comprising: (1) preparation of anti-aging microcapsules: dissolving an active component in an organic solvent, adding an inorganic material precursor thereto, and generating an inorganic material on the surface of the active component by liquid-phase deposition under the action of a catalyst to obtain anti-aging microcapsules; (2) coating treatment: mixing a polymer-modified matrix with the anti-aging microcapsules, and coating the anti-aging microcapsules on the surface of the polymer-modified matrix by mechanical force or solvent binding.

[0058] In some embodiments, a surface activation treatment may be performed prior to the coating process. This surface activation treatment modifies the polymer matrix surface using a silane coupling agent to improve the adhesion and uniformity of the antioxidant microcapsules on the polymer surface. The silane coupling agent is selected from KH-550, KH-560, and KH-570. Preferably, the silane coupling agent is KH-550.

[0059] In some embodiments, the organic solvent is selected from anhydrous ethanol, methanol, isopropanol, acetone or ethyl acetate; anhydrous ethanol is preferred.

[0060] In some embodiments, the inorganic precursor is selected from alkoxysilanes, inorganic silicates, aluminum alkoxides, and inorganic aluminum salts. In some embodiments, the aluminum alkoxide is selected from aluminum isopropoxide or aluminum isobutoxide. In some embodiments, the alkoxysilane is selected from tetraethyl orthosilicate (TEOS) or methyl orthosilicate (TMOS).

[0061] In some embodiments, when the inorganic material precursor is selected from aluminum alkoxides (e.g., aluminum isopropoxide or aluminum isobutoxide), the method further includes a step of calcining the encapsulated product. The calcination temperature is 120 to 180°C. Preferably, the calcination temperature is 140 to 160°C. In some embodiments, calcination is carried out under vacuum or nitrogen protection to protect the activity of the internal active components.

[0062] In some embodiments, the catalyst is selected from ammonia, sodium hydroxide, hydrochloric acid, and acetic acid. In some embodiments, preferably, the catalyst is ammonia. In some embodiments, the concentration of the catalyst can be from 0.1 to 2.0 mol / L. In some embodiments, the concentration of the catalyst can be from 0.1, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 to 2.0 mol / L.

[0063] In some embodiments, the coating process specifically includes dry blending of the polymer-modified matrix with the anti-aging microcapsules in a high-speed mixer or by solution blending, so that the anti-aging microcapsules are embedded or adhered to its surface.

[0064] In another aspect of this disclosure, a method for preparing modified asphalt is provided, comprising heating base asphalt to a molten state, adding the above-mentioned compound polymer modifier, performing high-speed shearing at a set temperature, adding a compatibilizer and a stabilizer after shearing, stirring and developing, and obtaining modified asphalt.

[0065] In some implementations, the heating temperature of the base bitumen is 130°C to 150°C.

[0066] In some embodiments, the high-speed shearing rate can be from 2000 to 5000 r / min. In some embodiments, the shearing time can be from 20 to 60 min. In some embodiments, the shearing temperature can be from 160°C to 180°C.

[0067] In some implementations, the temperature for stirring and developing can be 160°C to 180°C, and the development time can be 2 to 5 hours.

[0068] In some embodiments, based on 100 parts by weight of base bitumen, the amount of compound polymer modifier added is 3 to 8 parts by weight, the amount of compatibilizer added is 0.5 to 12 parts by weight, and the amount of stabilizer added is 0.1 to 0.3 parts by weight.

[0069] This disclosure employs a compound "polymer matrix-antioxidant" microencapsulation technology to address the performance degradation of polymer-modified asphalt caused by oxidation during high-temperature storage, long-term storage, or long-distance transportation. This technology holds significant technical importance and has promising application prospects. Through a double-layer encapsulation structure and a slow-release antioxidant design, this disclosure effectively delays oxygen diffusion and gradually releases the antioxidant, thereby improving the stability of asphalt during storage and transportation, and further enhancing its performance under high-temperature conditions.

[0070] Example

[0071] The effects and functions of this disclosure will be described in more detail below through specific embodiments thereof. However, these embodiments are for illustrative purposes only, and the scope of the claims of this disclosure is not defined thereto.

[0072] Example 1

[0073] (1) Preparation of antioxidant microcapsules

[0074] 8 g of antioxidant BHT (2,6-di-tert-butyl-p-cresol) was dissolved in 400 g of anhydrous ethanol and stirred until dissolved. 15 g of tetraethyl orthosilicate (TEOS) was added, and 4 g of ammonia was added as a catalyst at 45 °C. After reacting for 5 hours, the product was washed, dried, and crushed to obtain BHT@SiO2 microcapsule powder with a particle size of 80 to 150 nm.

[0075] (2) Preparation of compound polymer modifiers

[0076] 100 g of SBS (styrene-butadiene-styrene block copolymer) was put into a mixer, and 1.5 g of silane coupling agent KH-550 was sprayed for surface activation. Then, 12 g of microcapsule powder obtained in step (1) was added, and the mixture was mixed at high speed at 70°C for 10 minutes to form a continuous coating layer on the polymer surface, thus obtaining a compound polymer modifier.

[0077] (3) Preparation of modified asphalt

[0078] 70# base asphalt was heated to 165℃ to melt it. Based on 100 parts by weight of base asphalt, 5% of the compound polymer modifier obtained in step (2) was added. The mixture was sheared for 30 min at 4000 r / min using a high-speed shearing machine. After shearing, based on 100 parts by weight of base asphalt, 0.1% sulfur powder and 8% aromatic oil were added, and the mixture was developed at 180℃ for 2 hours to obtain modified asphalt.

[0079] Example 2

[0080] (1) Preparation of antioxidant microcapsules

[0081] Antioxidant 1010 and antioxidant 168 were compounded at a mass ratio of 1:1. Using aluminum isopropoxide as a precursor, hydrolysis was carried out under acidic conditions (pH adjusted to 4-5 by adding acetic acid). By controlling the reaction time, the compounded antioxidants were encapsulated in the resulting alumina gel. The encapsulated product was calcined at 135℃ to obtain modified alumina-coated antioxidant particles (i.e., antioxidant microcapsules).

[0082] (2) Preparation of compound polymer modifiers

[0083] 100 g of SBS was added to a mixer, and 1.5 g of silane coupling agent KH-550 was sprayed on for surface activation treatment. Then, 18 g of the above-mentioned alumina microcapsule powder was added, and the mixture was pre-dispersed by high-speed mixing at 80°C for 8 minutes to embed the microcapsules into the surface structure of the polymer, thus obtaining a compound polymer modifier.

[0084] (3) Preparation of modified asphalt

[0085] Modified asphalt was prepared in the same manner as step (3) of Example 1, except that the compound polymer modifier prepared in this example was used instead of the compound polymer modifier in Example 1, and the other conditions were the same.

[0086] Comparative Example 1

[0087] (1) Polymer-modified matrix

[0088] The same polymer-modified matrix as in Example 1 was directly selected without any microencapsulation treatment.

[0089] (2) Preparation of modified asphalt

[0090] 70# base asphalt was heated to 165°C to melt it. Based on 100 parts by weight of base asphalt, 5% polymer-modified matrix was added, and the same amount of antioxidant BHT as in Example 1 was directly added (i.e., without coating, directly added externally). Then, the same shearing process as in Example 1 was performed. After shearing, based on 100 parts by weight of base asphalt, 0.1% sulfur powder and 8% aromatic oil were added, and the mixture was developed at 180°C for 2 hours to obtain modified asphalt.

[0091] Comparative Example 2

[0092] (1) Polymer-modified matrix

[0093] The same polymer-modified matrix as in Example 1 was directly selected without any microencapsulation treatment.

[0094] (2) Preparation of modified asphalt

[0095] 70# base asphalt was heated to 170°C to melt it. Based on 100 parts by weight of base asphalt, 5% of a polymer-modified matrix was added. Then, the same shearing process as in Example 1 was performed. After shearing, based on 100 parts by weight of base asphalt, 0.1% of a sulfur-containing crosslinking agent and 8% rubber oil were added, and the mixture was developed at 180°C for 2 hours to obtain modified asphalt.

[0096] Comparative Example 3

[0097] (1) Preparation of antioxidant microcapsules

[0098] BHT@SiO2 microcapsule powder was prepared in exactly the same manner as step (1) of Example 1.

[0099] (2) Polymer-modified matrix

[0100] The same polymer-modified matrix as in Example 1 was used, without any microencapsulation treatment.

[0101] (3) Preparation of modified asphalt

[0102] 70# base asphalt was heated to 165°C to melt it. Based on 100 parts by weight of base asphalt, 5% of the above-mentioned polymer-modified matrix (uncoated) was added directly to it, and antioxidant microcapsule powder prepared in step (1) in the same amount as in Example 1 was added separately. The mixture was sheared at 4000 r / min for 30 min using a high-speed shearing machine. After shearing, based on 100 parts by weight of base asphalt, 0.1% sulfur powder and 8% aromatic oil were added, and the mixture was developed at 180°C for 2 hours to obtain modified asphalt.

[0103] Performance testing

[0104] To evaluate the performance of the polymer-modified asphalt disclosed in this paper, performance tests were conducted in accordance with the standard "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering (JTJ E20-2011)". The specific evaluation indicators are shown in Table 1.

[0105] Table 1 Comparison of Test Indicators

[0106]

[0107] The results above show that Examples 1 and 2 maintained a bright surface and no crusting during three consecutive days of high-temperature storage, and the difference in the segregation softening point was 0.7℃ and 0.2℃, respectively. This indicates that the compound modifier formed by encapsulating antioxidant microcapsules on the surface of the polymer-modified matrix can significantly inhibit the oxidative crusting of asphalt surface and effectively prevent phase separation between polymer and asphalt.

[0108] Both Comparative Example 1 and Comparative Example 2 showed varying degrees of crusting within 2 to 3 days of storage, with segregation softening point differences as high as 2.1℃ and 2.8℃, respectively. This indicates that simply adding antioxidants to asphalt or not adding antioxidants cannot solve the oxidation and segregation problems under high temperature conditions. It also shows that conventional antioxidants are easily volatilized and depleted at high temperatures, and the polymer undergoes severe cross-linking and aging.

[0109] The results of Comparative Example 3 showed that no skin formation occurred within 2 days of storage, which was superior to Comparative Examples 1 and 2. However, slight skin formation occurred on the third day, and the difference in the segregation softening point was 1.5°C, which was still significantly worse than Examples 1 and 2. This indicates that simply adding microcapsule powder and polymer particles separately to asphalt can provide some antioxidant protection, but because the microcapsules fail to adhere tightly to the polymer surface, a localized high-concentration protective layer cannot be formed on the polymer surface, and the improvement on interfacial compatibility is limited.

[0110] To further verify the thermal stability of the inorganic wall material used in this disclosure, thermogravimetric analysis was performed on the microcapsules prepared in Examples 1 and 2, and the test results are shown in Table 2.

[0111] Table 2. Thermogravimetric loss rate (%) at different temperatures

[0112]

[0113] As shown in Table 2, the weight loss rates of Examples 1 and 2 are both less than 1% at 200°C and less than 2.5% at 300°C. Even when the temperature is increased to 500°C, the weight loss rates are approximately 6.5% and 5.0%, respectively. This indicates that the inorganic wall material used in this disclosure has excellent thermal stability and can maintain structural integrity under high-temperature asphalt processing and storage conditions, effectively playing a physical barrier and slow-release protective role.

[0114] This disclosure discloses a composite structure formed by pre-encapsulating microcapsules on the surface of a polymer, achieving a synergistic effect of physical barrier and chemical slow release, and unexpectedly improving the interfacial bonding between the polymer and asphalt, thereby achieving better storage stability. Based on the above analysis, the composite microcapsule technology has excellent application value for the long-distance transportation and long-term storage stability of polymer-modified asphalt.

[0115] Although several embodiments of this disclosure have been described and illustrated herein, those skilled in the art will readily contemplate a variety of other ways and / or structures for performing the functions described herein and / or obtaining the results described herein and / or one or more advantages, and each such variation and / or modification is considered to be within the scope of this disclosure.

Claims

1. A compound polymer modifier, comprising: Polymer-modified matrix; and A functional layer is coated on the surface of the polymer-modified matrix; the functional layer includes an inorganic material and an active component encapsulated within the inorganic material. The active component described therein has anti-aging properties.

2. The compound polymer modifier according to claim 1, wherein the functional layer is composed of anti-aging microcapsules, wherein the anti-aging microcapsules use the inorganic material as the wall material and the active component as the core material.

3. The compound polymer modifier according to claim 1 or 2, wherein the compound polymer modifier is particulate and has a core-shell structure, the polymer modified matrix constitutes the core, and the functional layer constitutes the shell.

4. The compound polymer modifier according to any one of claims 1 to 3, wherein: Based on the total mass of the compounded polymer modifier, the polymer-modified matrix accounts for 80% to 90% of the mass, and the functional layer accounts for 10% to 20% of the mass; and In the functional layer, the mass ratio of the inorganic material to the active component is 1:1 to 3:

1.

5. The compound polymer modifier according to any one of claims 1 to 4, wherein: The polymer-modified matrix is ​​selected from thermoplastic elastomers, rubbers, and thermoplastic resins; The active ingredient is selected from hindered phenolic antioxidants and phosphite antioxidants, and The inorganic material is selected from inorganic oxides and inorganic silicates; preferably, the inorganic material is selected from silicon dioxide and modified alumina.

6. A modified bitumen comprising: Base bitumen; and The compound polymer modifier according to any one of claims 1 to 5 dispersed in the base asphalt.

7. The modified bitumen according to claim 6, wherein the content of the compound polymer modifier is 3 to 12 parts by weight, for example 3, 4, 5, 6, 7, 8, 10 to 12 parts by weight, preferably 3 to 8 parts by weight, based on 100 parts by weight of the base bitumen.

8. The modified bitumen according to claim 6 or 7, further comprising a compatibilizer selected from aromatic oils, naphthenic oils, rubber oils, styrene-butadiene block copolymers and maleic anhydride graft polymers, preferably aromatic oils.

9. The modified bitumen according to any one of claims 6 to 8, further comprising a stabilizer selected from sulfur powder, elemental sulfur and sulfur-containing crosslinking agents, preferably sulfur powder.

10. A method for preparing a compound polymer modifier according to any one of claims 1 to 5, comprising: (1) Preparation of anti-aging microcapsules: The active component is dissolved in an organic solvent, an inorganic material precursor is added to it, and the inorganic material is generated on the surface of the active component by liquid phase deposition under the action of a catalyst to obtain anti-aging microcapsules; (2) Coating treatment: The polymer-modified matrix is ​​mixed with the anti-aging microcapsules, and the anti-aging microcapsules are coated on the surface of the polymer-modified matrix by mechanical force or solvent binding.

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