Composite emulsion for enhancing adhesive property of emulsified asphalt and preparation method thereof

Abstract

The invention discloses a composite emulsion for enhancing the adhesive property of emulsified asphalt and a preparation method, and relates to the technical field of high polymer materials and composite materials, the emulsion is a cationic or nonionic aqueous acrylic acid-butadiene core-shell structure emulsion, the shell layer contains an acrylate hard monomer or a methacrylate hard monomer, and the shell layer contains an acrylate monomer or a methacrylate monomer. The preparation method comprises the following steps: adding an emulsifier and an initiator into a water phase at 60-80 DEG C, dropwise adding a core layer monomer mixed solution, and carrying out heat preservation reaction to form a seed emulsion; synchronously dropwise adding a shell layer monomer pre-emulsion and an initiator solution into the seed emulsion, and carrying out heat preservation reaction to construct a core-shell structure; and cooling the reaction system, adjusting the pH value to 4-6, adding an antioxidant and an ultraviolet absorbent, and filtering to obtain the final composite emulsion. By designing a core-shell structure with specific charge characteristics and introducing a tertiary amine functional monomer and a post-treatment process, the composite emulsion which is good in stability, strong in affinity with a negatively charged base material and excellent in aging resistance can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and composite materials technology, and in particular relates to a composite emulsion for enhancing the bonding performance of emulsified asphalt and its preparation method. Background Technology

[0002] Waterborne acrylic-butadiene emulsions combine the weather resistance of acrylates with the flexibility of butadiene, and are widely used in coatings, adhesives, and other fields. However, traditional anionic emulsions of this type exhibit charge repulsion when bonding with negatively charged substrates (such as acidic aggregates, old asphalt pavements, and paper fibers), leading to poor adhesion and incompatible properties. Particularly in cationic emulsified asphalt systems, the incorporation of anionic polymer emulsions easily causes demulsification and flocculation, hindering their ability to achieve modification effects.

[0003] Although cationic polymer emulsions can effectively improve affinity with negatively charged substrates, existing cationic acrylic-butadiene emulsions suffer from poor stability, limited functional group design, and insufficient aging resistance inherent in butadiene segments, which restricts their promotion in high-performance applications.

[0004] Patents such as CN118290955A, CN1618862A, and CN111218008A all employ solvents such as n-hexane, toluene, cyclohexane, and ethyl acetate to dissolve styrene-butadiene-styrene block copolymers, followed by emulsification and solvent extraction to obtain water-based styrene-butadiene-styrene block copolymer latex. These solvents are all toxic and harmful, posing significant safety and environmental risks to personnel and the environment. The emulsions produced using this simple, single process require further improvement in solid content, stability, and room-temperature film-forming properties. Therefore, the following solutions are proposed to address these issues. Summary of the Invention

[0005] The purpose of this invention is to provide a composite emulsion for enhancing the adhesion performance of emulsified asphalt and its preparation method. By designing a core-shell structure with specific charge characteristics and introducing tertiary amine functional monomers and post-processing, a composite emulsion with good stability, strong affinity for negatively charged substrates, and excellent aging resistance can be prepared. This solves the problems of poor adhesion caused by charge repulsion between anionic emulsions and negatively charged substrates, insufficient stability of cationic emulsions, single functional group design, use of toxic solvents in some processes, low solid content of products, and poor adhesion and film-forming properties.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a composite emulsion for enhancing the bonding performance of emulsified asphalt. The emulsion is a cationic or nonionic aqueous acrylic-butadiene core-shell structure emulsion, the shell of which contains acrylate hard monomers or methacrylate hard monomers, as well as tertiary amine functional monomers. The tertiary amine functional monomers account for 1% to 5% of the total monomer mass of the emulsion. The pH of the emulsion is adjusted to 4 to 6 by organic acid to give it a stable positive charge on its surface.

[0007] Furthermore, the tertiary amine functional monomer is an acrylate or methacrylate containing a tertiary amine group, preferably dimethylaminoethyl methacrylate.

[0008] A method for preparing a composite emulsion to enhance the bonding properties of emulsified asphalt includes the following steps: Step S1, Core layer preparation: In an aqueous phase at 60°C to 80°C, add emulsifier and initiator, and then dropwise add core layer monomer mixture, which contains butadiene monomer, styrene and acrylate soft monomer or methacrylate soft monomer. After the dropwise addition is complete, keep the reaction at the temperature for 1 to 3 hours. Step S2, Shell preparation: Add shell monomer pre-emulsion and initiator solution to the seed emulsion obtained in step S1 simultaneously. The shell monomer pre-emulsion contains acrylate hard monomer or methacrylate hard monomer and tertiary amine functional monomer. The tertiary amine functional monomer accounts for 1% to 5% of the total monomer mass of the emulsion. After the addition is completed, keep the reaction at the temperature for 1 to 3 hours. Step S3, Post-processing: Cool the reaction system to below 40°C, add organic acid to adjust the pH to 4 to 6, and obtain the composite emulsion.

[0009] Further, in steps S1 and S2, the emulsifier is a cationic emulsifier or a nonionic emulsifier; the cationic emulsifier is a quaternary ammonium salt emulsifier; and the nonionic emulsifier is a polyether emulsifier.

[0010] Furthermore, in step S3, after adjusting the pH, 0.1% to 1.5% of an antioxidant and a UV absorber, accounting for 0.1% to 1.5% of the total mass of the emulsion, are added. Furthermore, the initiator is a water-soluble azo initiator.

[0011] An application of the composite emulsion as described above in enhancing the bonding performance between cationic emulsified asphalt and aggregates involves incorporating the composite emulsion into cationic emulsified asphalt to improve the bonding strength between modified emulsified asphalt and negatively charged aggregates, or to improve the early strength and abrasion resistance of the mixture.

[0012] A modified emulsified asphalt composition for enhancing adhesion properties comprises cationic emulsified asphalt and the composite emulsion as described in claim 1 or 2.

[0013] The present invention has the following beneficial effects: 1. Through core-shell structure design, the flexibility of butadiene is combined with the weather resistance of acrylate. The core layer provides flexibility and adhesion, while the shell layer provides hardness and functional groups. The synergistic effect makes the emulsion have excellent overall performance.

[0014] 2. By using tertiary amine functional monomers and organic acid post-treatment, the surface of the emulsion particles is given a stable positive charge, which has a strong affinity with negatively charged substrates. It is particularly suitable for cationic emulsified asphalt systems and can improve the bond strength with aggregates and the early strength of the mixture.

[0015] 3. By optionally adding antioxidants and UV absorbers, the aging resistance of butadiene segments is effectively improved, extending the service life of the products.

[0016] 4. The emulsion has good stability, excellent mechanical and chemical stability, and is easy to store and apply.

[0017] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a method for preparing a composite emulsion to enhance the bonding properties of emulsified asphalt according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention relates to a composite emulsion for enhancing the bonding performance of emulsified asphalt and its preparation method. The emulsion is a cationic or nonionic aqueous acrylic-butadiene core-shell structure emulsion, the shell of which contains acrylate hard monomers or methacrylate hard monomers, as well as tertiary amine functional monomers. The tertiary amine functional monomers account for 1% to 5% of the total monomer mass of the emulsion. The pH of the emulsion is adjusted to 4 to 6 by organic acid to give it a stable positive charge on its surface.

[0022] The tertiary amine functional monomer is an acrylate or methacrylate containing a tertiary amine group, preferably dimethylaminoethyl methacrylate.

[0023] Please see Figure 1 As shown, a method for preparing a composite emulsion to enhance the bonding properties of emulsified asphalt includes the following steps: Step S1, Core layer preparation: In an aqueous phase at 60°C to 80°C, add emulsifier and initiator, and then dropwise add core layer monomer mixture, which contains butadiene monomer, styrene and acrylate soft monomer or methacrylate soft monomer. After the dropwise addition is complete, keep the reaction at the temperature for 1 to 3 hours. Step S2, Shell preparation: Add shell monomer pre-emulsion and initiator solution to the seed emulsion obtained in step S1 simultaneously. The shell monomer pre-emulsion contains acrylate hard monomer or methacrylate hard monomer, as well as tertiary amine functional monomer. The tertiary amine functional monomer accounts for 1% to 5% of the total monomer mass of the emulsion. After the addition is completed, keep the reaction at the temperature for 1 to 3 hours. Step S3, Post-treatment: Cool the reaction system to below 40°C, add organic acid to adjust the pH to 4 to 6, and obtain the composite emulsion. In steps S1 and S2, the emulsifier is either a cationic emulsifier or a nonionic emulsifier; the cationic emulsifier is a quaternary ammonium salt emulsifier; and the nonionic emulsifier is a polyether emulsifier.

[0024] In step S3, after adjusting the pH, antioxidants and UV absorbers are added at a concentration of 0.1% to 1.5% of the total emulsion mass. The initiator is a water-soluble azo initiator.

[0025] An application of the composite emulsion as described above in enhancing the bonding performance between cationic emulsified asphalt and aggregates involves incorporating the composite emulsion into cationic emulsified asphalt to improve the bonding strength between modified emulsified asphalt and negatively charged aggregates, or to improve the early strength and abrasion resistance of the mixture.

[0026] A modified emulsified asphalt composition for enhancing adhesion properties comprises cationic emulsified asphalt and a composite emulsion as claimed in claim 1 or 2.

[0027] The specific application of this embodiment is as follows: Example 1 (Cat type) 1. Core layer preparation: Add 100 parts deionized water, 2.0 parts hexadecyltrimethylammonium bromide, and 0.3 parts sodium bicarbonate to a reaction vessel and heat to 70°C. Add 1 / 3 of the total volume of VA-044 aqueous solution (0.2 parts VA-044 dissolved in 5 parts water), and then dropwise add the core layer mixture (60 parts butadiene emulsion (50% solid content, Tg < -50°C), 10 parts styrene, and 15 parts butyl acrylate), completing the addition over 2 hours, and maintain the temperature for 1 hour.

[0028] 2. Shell preparation: Simultaneously add shell pre-emulsion (25 parts methyl methacrylate, 10 parts butyl acrylate, 4 parts dimethylaminoethyl methacrylate, emulsified with 10 parts water) and the remaining 2 / 3 of VA-044 aqueous solution (0.4 parts VA-044 dissolved in 10 parts water), add dropwise over 3 hours, and keep warm for 1.5 hours.

[0029] 3. Post-processing: Cool to 40℃, add lactic acid to adjust pH to 5.0, add 0.3 parts antioxidant 1076 and 0.2 parts ultraviolet absorber UV-P, and filter to obtain a cationic emulsion with a solid content of about 45%.

[0030] Example 2 (Non-ionic type) Replace the emulsifier with 2.5 parts of BASF Pluronic® PE 6100, and the rest is the same as in Example 1.

[0031] Comparative Example 1 Non-tertiary amine functional monomer: Based on Example 1, dimethylaminoethyl methacrylate was removed from the shell pre-emulsion and replaced with an equal amount of methyl methacrylate, while the other conditions remained unchanged.

[0032] Comparative Example 2 Anionic emulsion: Replace the emulsifier with 2.0 parts of sodium dodecyl sulfate (SDS), do not adjust the pH in the post-treatment, and the rest is the same as in Example 1.

[0033] I. Performance Testing 1. Emulsion properties: Table 1. Results of Emulsion Performance Tests sample Zeta potential (mV) Mechanical stability (3000 r / min, 30 min) Calcium ion stability (0.5% CaCl2, 48h) Example 1 +35.2 pass pass Example 2 +5.1 pass pass Comparative Example 1 10.5 pass pass Comparative Example 2 -40.3 pass Failed (flocculation) 2. Asphalt application performance (the emulsions of Examples 1 and 2 and Comparative Examples 1 and 2 were added to the same cationic emulsified asphalt at a dosage of 3%): Table 2 Performance test results of modified emulsified asphalt sample Storage stability (1D, difference between upper and lower layers) Bond strength with granite aggregate (MPa) Wet wheel wear value (WTAT, g / m2) Example 1 0.5% 1.25 450 Example 2 0.8% 1.10 480 Comparative Example 1 2.5% (stratified) 0.75 550 Comparative Example 2 Broken nipple, unable to be tested Unable to test Unable to test The results above show that the cationic / nonionic emulsions provided by this invention (Examples 1 and 2) have excellent stability and compatibility with cationic emulsified asphalt, and can improve the bond strength and abrasion resistance of modified asphalt and aggregate. Comparative Example 1 (without tertiary amine functional monomer) and Comparative Example 2 (anionic) performed poorly, demonstrating the rationality and inventiveness of this invention.

[0034] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A composite emulsion for enhancing the cohesive properties of emulsified asphalt, characterized by, The emulsion is a cationic or non-ionic aqueous acrylic-butadiene core-shell structure emulsion, the shell layer of which comprises an acrylate hard monomer or a methacrylate hard monomer, and a tertiary amine functional monomer; the tertiary amine functional monomer accounts for 1% to 5% of the total monomer mass of the emulsion; the emulsion is adjusted to a pH of 4 to 6 by an organic acid, so that its surface has a stable positive charge.

2. The composite emulsion for enhancing the binding performance of emulsified asphalt according to claim 1, characterized by, The tertiary amine functional monomer is an acrylate or methacrylate containing a tertiary amine group, preferably dimethylaminoethyl methacrylate.

3. A method for preparing a complex emulsion for enhancing the cohesive properties of emulsified asphalt, characterized by, The preparation method comprises the following steps: Step S1, core layer preparation: in an aqueous phase at 60-80°C, emulsifiers and initiators are added, and then a core layer monomer mixture containing butadiene monomers, styrene and acrylate soft monomers or methacrylate soft monomers is added dropwise, and after the dropwise addition is completed, the reaction is incubated for 1-3 hours; Step S2, shell layer preparation: to the seed emulsion obtained in step S1, a shell layer monomer pre-emulsion containing acrylate hard monomers or methacrylate hard monomers, and a tertiary amine functional monomer accounting for 1% to 5% of the total monomer mass of the emulsion, and an initiator solution are added dropwise at the same time, and after the dropwise addition is completed, the reaction is incubated for 1-3 hours; Step S3, post-treatment: the reaction system is cooled to below 40°C, an organic acid is added to adjust the pH to 4-6, and the composite emulsion is obtained.

4. The complex emulsion for enhancing the binding performance of emulsified asphalt according to claim 3, wherein In steps S1 and S2, the emulsifier is a cationic emulsifier or a non-ionic emulsifier; the cationic emulsifier is a quaternary ammonium salt emulsifier; the non-ionic emulsifier is a polyether emulsifier.

5. The complex emulsion for enhancing the binding performance of emulsified asphalt according to claim 3, wherein In step S3, after adjusting the pH, 0.1%-1.5% of an antioxidant and a UV absorber based on the total mass of the emulsion are also added.

6. The complex emulsion for enhancing the binding performance of emulsified asphalt according to claim 3, wherein The initiator is a water-soluble azo initiator.

7. Use of the composite emulsion according to claim 1 or 2 for enhancing the cationic emulsified bitumen-aggregate adhesion properties, characterized in that, The composite emulsion is incorporated into cationic emulsified asphalt to improve the bonding strength of modified emulsified asphalt to negatively charged aggregates, or to improve the early strength and wear resistance of the mixture.

8. A modified emulsified asphalt composition for enhancing adhesion properties, characterized by, It comprises cationic emulsified asphalt and the composite emulsion of claim 1 or 2.

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