Microcapsule, preparation method therefor, and use thereof

Abstract

A microcapsule, a preparation method therefor, and a use thereof. The microcapsule comprises a capsule core and a capsule wall. The capsule core is wrapped in the capsule wall. The capsule core contains an active ingredient. The elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y=0.42X2-0.92X+T, wherein Y is the elastic modulus of the microcapsule, and the unit thereof is GPa; X is the thickness of the capsule wall, and the unit thereof is μm; and T is 1±0.1. The elastic modulus of the microcapsule is obtained by performing a mechanical property test on the microcapsule by using a nano-indentation instrument. The thickness of the capsule wall is obtained by performing frozen section on the microcapsule by using a scanning electron microscope. The microcapsule is suitable for pavement asphalt, and the self-repairing efficiency of a pavement asphalt material can be effectively improved. In addition, in a process of asphalt construction, the emission of an asphalt flue gas can be effectively reduced and the pollution to the environment is reduced.

Description

A microcapsule and its preparation method and application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application No. 202311125654.2 filed on September 1, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the technical field of microcapsule materials, in particular to a microcapsule and a preparation method and application thereof, and more particularly to a microcapsule and a preparation method thereof and application of the microcapsule in road asphalt. Background Art

[0004] During the use of asphalt pavement, due to the influence of vehicle loads and environmental factors, micro cracks and local damage are very likely to appear inside. If not controlled in time, the micro cracks will expand and crack under the action of external loads, leading to the formation of macro cracks. Water seepage at the cracks will further aggravate the damage to the pavement structure, making it impossible for the road to reach its designed service life. Since micro cracks in asphalt pavement are often generated internally, it is very difficult to detect such micro damage in a timely manner, and it is almost impossible to carry out manual repairs. As a result, it is difficult to repair early cracks. In severe cases, macro cracks will be triggered and lead to structural fractures. Current repair methods only take remedial measures after obvious cracks appear on the pavement. Although this type of repair can solve the existing problem, it is bound to have a certain impact on traffic, resulting in multiple losses of manpower and material resources.

[0005] Using microencapsulation technology, a repair agent is encapsulated in microcapsules. Adding this to asphalt enables the automatic repair of pavement cracks. When microcracks develop in the asphalt due to aging or load, the microcapsules in the crack path rupture due to the expansion of the tip stress. The repair agent is released from the microcapsule wall material and, driven by capillary action, flows along the microcracks, penetrating and diffusing to both sides, gradually eliminating the microcracks and ultimately achieving the self-healing effect of the asphalt. During asphalt pavement use, the microcapsules must be strong enough to avoid rupture during mixing of the asphalt mixture. However, if the microcapsules are too strong, microcracks in the asphalt pavement can easily bypass the microcapsules and propagate forward, making it difficult for the microcapsules to rupture and thus failing to perform their repair function.

[0006] Chinese patent application CN104231642A discloses a self-repairing microcapsule for asphalt cracks containing a regeneration agent and a preparation method thereof. This method uses polyurea formaldehyde resin as the wall material and an asphalt regeneration agent as the core material to prepare the self-repairing microcapsules for asphalt cracks. The microcapsules can enhance the self-repairing ability of asphalt pavement to a certain extent. However, the microcapsules are not tightly bonded to the asphalt, making it difficult for the microcapsules to break, which affects the self-repairing efficiency of the microcapsules.

[0007] In summary, the existing technology does not take into account the bonding strength between microcapsules and asphalt. It simply adds microcapsules to asphalt. The two cannot be effectively integrated, making it easy for the microcapsules to separate from the asphalt, further exacerbating the phenomenon that the microcapsules are difficult to break.

[0008] In addition, asphalt pavement is the main type of highway, and its pavement construction still uses the traditional hot-mix hot-paving process. During the construction process, the asphalt will come into contact with oxygen in the air and react: on the one hand, a condensation reaction will occur to produce polycyclic aromatic hydrocarbons with larger molecular weight, which will further condense into gums and asphalt; on the other hand, the asphalt molecules will undergo cracking under heat conditions to produce compounds with smaller molecular weight. These small molecular compounds will evaporate to form asphalt smoke, which will seriously damage the ecological balance, pollute the surrounding environment and harm human health.

[0009] Given that asphalt pavement releases volatile organic compounds (VOCs) in an unorganized manner during paving, it is difficult to collect and control the entire process. Exploring how to reduce asphalt fume release at the source, achieve clean asphalt pavement construction, and ensure the harmonious development of the transportation industry and the social economy is an urgent issue that needs to be addressed.

[0010] Summary of the Invention

[0011] The present invention aims to overcome the existing problem of microcapsules not effectively fusing with asphalt after addition, resulting in the microcapsules easily separating from the asphalt. The invention provides novel microcapsules, their preparation method, and applications. The microcapsules described in the present invention not only possess high strength, meeting the requirements for pavement use, but also exhibit excellent bonding strength with asphalt.

[0012] In order to achieve the above object, the present invention provides a microcapsule, which includes a capsule core and a capsule wall, wherein the capsule core is wrapped in the capsule wall, and the capsule core contains an active component. The elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0013] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0014] The elastic modulus of the microcapsule is obtained by testing the mechanical properties of the microcapsule using a nanoindenter, and the thickness of the capsule wall is obtained by testing the frozen sections of the microcapsule using a scanning electron microscope.

[0015] Preferably, based on the total weight of the microcapsule, the content of the capsule core is 27-53 wt.%, and the content of the capsule wall is 47-73 wt.%.

[0016] Preferably, the active component is a repairing agent for self-repair of pavement cracks and / or an inhibitor for inhibiting the release of asphalt smoke.

[0017] Preferably, the repairing agent for self-repair of pavement cracks is an aromatic hydrocarbon-rich component.

[0018] Preferably, the aromatics-rich component is selected from at least one of catalytic cracking slurry, oil extracted from a fourth-line reduction reactor, furfural extracted oil and waste lubricating oil.

[0019] Preferably, the aromatic content of the aromatic-rich component is 45-65 wt.%.

[0020] Preferably, the inhibitor for suppressing the release of asphalt fume is at least one of aldehyde compounds, ketone compounds, alcohol compounds, phenol compounds and ester compounds.

[0021] Preferably, the aldehyde compound is selected from aliphatic aldehydes having carbon atoms greater than or equal to 7 and aromatic aldehydes having carbon atoms greater than or equal to 6, more preferably at least one of p-methylbenzaldehyde, decanal, o-carboxybenzaldehyde, p-isopropylbenzaldehyde, cinnamaldehyde, p-hydroxybenzaldehyde, p-methoxybenzaldehyde, 2-methyl-3-(3,4-methylene-dioxyphenyl)propionaldehyde, 3,4-methylenedioxybenzaldehyde, 3-(4-isopropylphenyl)-2-methylpropionaldehyde, ethyl vanillin, phenylacetaldehyde, anisaldehyde, nonadiene-2,6-aldehyde, 2,6-dimethyl-2,6-octadienal, vanillin, citronellal, neral, hydroxymethylpentylcyclohexene acetal, p-diethylaminobenzaldehyde and undecenal.

[0022] Preferably, the ketone compound is selected from aliphatic ketones having carbon atoms greater than or equal to 8 and aromatic ketones having carbon atoms greater than or equal to 8, more preferably at least one of 6-methyl-3,5-heptadien-2-one, 2-undecanone, acetophenone, ionone, irone, methylionone, damascone and dihydrodamascone.

[0023] Preferably, the alcohol compound is an alcohol having more than 6 carbon atoms, more preferably at least one of cinnamyl alcohol, menthol, cis-3,7-dimethyl-2,6-octadienol, citronellol, geraniol, myrcenol, 2,6,10-trimethyl-2,6,10-dodecatrien-12-ol, lavandulol, benzyl alcohol, 2-phenylethanol, dihydromyrcenol, tetrahydrogeraniol and nerolidol.

[0024] Preferably, the phenolic compound is a phenol having 6 or more carbon atoms, more preferably at least one of thymol, ethyl maltol, methyl maltol, 3-propenyl-6-ethoxyphenol and isoeugenol.

[0025] Preferably, the ester compound is an ester having more than 7 carbon atoms, more preferably at least one of methyl salicylate, methyl cinnamate, ethyl cinnamate, ethyl phenylacetate, methyl phenylacetate, geranyl phenylacetate, phenylethyl phenylacetate, isoamyl phenylacetate, benzyl salicylate, p-methylbenzyl acetate, benzyl acetate, isobutyl benzoate, isoamyl salicylate, benzyl cinnamate, phenylethyl cinnamate, linalyl formate, linalyl acetate, linalyl isobutyrate, menthyl acetate, terpineol acetate, and bornyl acetate.

[0026] Preferably, the thickness of the capsule wall is 0.5-5 μm.

[0027] Preferably, the bladder wall comprises an inner layer and an outer layer, the inner layer is made of resin, and the outer layer is made of rubber material.

[0028] Preferably, the mass ratio of the inner layer to the outer layer is 2.4-5:1.

[0029] Preferably, the resin is at least one of melamine resin, urea-formaldehyde resin and polymethyl methacrylate, preferably melamine resin.

[0030] Preferably, the rubber material is at least one of chlorinated rubber, styrene-butadiene rubber and chloroprene rubber.

[0031] Preferably, the size of the microcapsules is 50 μm or less, preferably 20 μm or less, more preferably 3-15 μm.

[0032] A second aspect of the present invention provides a method for preparing microcapsules, the method comprising:

[0033] (1) mixing the active ingredient, emulsifier and water to form an oil-in-water emulsion;

[0034] (2) reacting the oil-in-water emulsion with a resin prepolymer, and then filtering, washing, and drying to obtain a pre-coated material;

[0035] (3) In the presence of a volatile solvent, the rubber material and the pre-coated material are mixed, and then the obtained mixture is mixed with water, and the temperature is raised until the volatile solvent evaporates to obtain microcapsules.

[0036] Preferably, in step (1), the mass ratio of the active component, the emulsifier and water is 1: (0.05-0.09): (6-9).

[0037] Preferably, in step (2), before the oil-in-water emulsion reacts with the resin prepolymer, the pH value of the oil-in-water emulsion is adjusted to below 5, preferably 2-4.

[0038] Preferably, in step (2), the resin prepolymer is a melamine resin prepolymer.

[0039] Preferably, the preparation method of the melamine resin prepolymer comprises: mixing and dissolving melamine and formaldehyde solution with water, adjusting the pH value to 7.5-9.5, and then placing the mixture in a constant temperature water bath at 60-90° C. and reacting for 0.5-3.5 hours under stirring.

[0040] Preferably, the concentration of the formaldehyde solution is 30-40 wt.%.

[0041] Preferably, the mass ratio of the melamine, the formaldehyde solution and water is 1:(2-3):(8-10).

[0042] Preferably, in step (3), the mass ratio of the rubber material, the volatile solvent and water is 1:(10-20):(50-150).

[0043] Preferably, the active component is one or any combination of at least two or more of an aromatic hydrocarbon-rich component, an aldehyde compound, a ketone compound, an alcohol compound, a phenol compound and an ester compound.

[0044] Preferably, the rubber material is at least one of chlorinated rubber, styrene-butadiene rubber and chloroprene rubber.

[0045] Preferably, the emulsifier is selected from at least one of sodium stearate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, cetyltrimethylammonium chloride, cetyltrimethylammonium bromide, cetyldimethylhydroxyethylammonium chloride, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether and hexadecane polyoxyethylene ether.

[0046] Preferably, the volatile solvent is selected from at least one of carbon tetrachloride, dichloromethane and trichloroethylene.

[0047] The third aspect of the present invention provides microcapsules prepared by the above method.

[0048] A fourth aspect of the present invention provides the use of the above-mentioned microcapsules in road asphalt.

[0049] According to the microcapsules of the present invention, the elastic modulus of the microcapsules satisfies a specific functional relationship with the thickness of the capsule wall. In practical applications, the elastic modulus of the microcapsules can be controlled within a desired parameter range by adjusting the thickness of the capsule wall.

[0050] In a preferred embodiment, the active component in the capsule core is a repair agent for self-repairing pavement cracks, and the capsule wall comprises an inner layer and an outer layer, the inner layer being a resin and the outer layer being a rubber material. The microcapsules of this preferred embodiment are particularly suitable for pavement asphalt. On the one hand, the microcapsules possess a certain strength, meeting the requirements for pavement use. On the other hand, the rubber material, which serves as the outer capsule wall, effectively fuses with asphalt. The rubber material has excellent adhesion and forms a strong bond with the resin (particularly melamine resin) serving as the inner capsule wall. When cracks appear in the asphalt pavement, the probability of material rupture is effectively increased. Tearing of the outer capsule wall drives the tearing of the inner capsule wall, releasing the repair agent and achieving the purpose of self-repair. The two capsule wall materials complement each other's strengths, thereby effectively improving the self-repair efficiency of pavement asphalt materials.

[0051] In another preferred embodiment, the active ingredient in the capsule core is an inhibitor for suppressing asphalt fume release, and the capsule wall comprises an inner layer made of resin and an outer layer made of rubber. The microcapsules of this preferred embodiment are particularly suitable for use in road asphalt. The microcapsule structure prolongs the active ingredient's action, extending the storage and service life of the asphalt. This effectively reduces asphalt fume emissions and environmental pollution during asphalt construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG1 is a SEM image of the microcapsules prepared in Example 1. DETAILED DESCRIPTION

[0053] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0054] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0055] The microcapsule of the present invention comprises a capsule core and a capsule wall, wherein the capsule core is wrapped in the capsule wall and contains active components. The elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0056] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0057] The elastic modulus of the microcapsule is obtained by testing the mechanical properties of the microcapsule using a nanoindenter, and the thickness of the capsule wall is obtained by testing the frozen sections of the microcapsule using a scanning electron microscope.

[0058] In the microcapsules of the present invention, the thickness of the capsule wall can be 0.5-5 μm, specifically, for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.1 μm, 2.2 μm, 2.3 μm, 2.4 μm, 2.5μm, 2.6μm, 2.7μm, 2.8μm, 2.9μm, 3μm, 3.1μm, 3.2μm, 3.3μm, 3.4μm, 3.5μm, 3.6μm, 3.7 μm, 3.8μm, 3.9μm, 4μm, 4.1μm, 4.2μm, 4.3μm, 4.4μm, 4.5μm, 4.6μm, 4.7μm, 4.8μm, 4.9μm or 5μm.

[0059] In some embodiments, the thickness of the capsule wall is 0.5-2 μm, preferably 0.5-1.5 μm. The capsule wall of the microcapsule of this embodiment is thinner and the elastic modulus of the microcapsule is smaller, which is suitable for application scenarios requiring rapid release of the active component in the capsule core.

[0060] In other embodiments, the thickness of the capsule wall is 2-3 μm. The capsule wall of the microcapsule of this embodiment is moderate, and the elastic modulus of the microcapsule is moderate, which is suitable for application scenarios requiring the release of the active component in the capsule core at a moderate speed.

[0061] In other embodiments, the thickness of the capsule wall is 3-5 μm. The capsule wall of the microcapsule of this embodiment is thicker and the elastic modulus of the microcapsule is larger, which is suitable for application scenarios requiring slow release of the active component in the capsule core.

[0062] In the microcapsules of the present invention, the size of the microcapsules may be less than 50 μm, preferably less than 20 μm, and more preferably 3-15 μm.

[0063] In the microcapsules of the present invention, based on the total weight of the microcapsules, the content of the capsule core may be 27-53 wt.%, and the content of the capsule wall may be 47-73 wt.%. In some embodiments, in the microcapsules, the content of the capsule core may be 40-53 wt.%, and the content of the capsule wall may be 47-60 wt.%. In other embodiments, in the microcapsules, the content of the capsule core may be 30-40 wt.%, and the content of the capsule wall may be 60-70 wt.%. In other embodiments, in the microcapsules, the content of the capsule core may be 27-30 wt.%, and the content of the capsule wall may be 70-73 wt.%.

[0064] In the microcapsules described in the present invention, the active components can be various conventional active components in slow-release application scenarios. In some embodiments, the active component is a repair agent for self-repair of pavement cracks and / or an inhibitor for suppressing the release of asphalt fumes. When the active component in the microcapsule is a repair agent for self-repair of pavement cracks, in the event of cracks in the asphalt pavement, the probability of material rupture can be effectively increased, and the tearing of the outer wall layer drives the tearing of the inner wall layer, releasing the repair agent, thereby achieving the purpose of automatic repair. When the active component in the microcapsule is an inhibitor for suppressing the release of asphalt fumes, the structure of the microcapsule can extend the action time of the active component, so that the asphalt composition has a longer storage and service life, and can effectively reduce the emission of asphalt fumes during the asphalt construction process, reducing pollution to the environment.

[0065] In the present invention, the repair agent for self-repair of pavement cracks is preferably an aromatics-rich component. The aromatics-rich component refers to a material with an aromatics content of 40 wt.% or more. As a specific material selection, the aromatics-rich component can be selected from at least one of catalytic cracking slurry, oil extracted from a four-line reduction, furfural extracted oil, and waste lubricating oil. In a preferred embodiment, the aromatics content of the aromatics-rich component is 45-65 wt.%, more preferably 50-60 wt.%, and even more preferably 52-56 wt.%.

[0066] In the present invention, the inhibitor for suppressing the release of asphalt fume is preferably at least one of aldehyde compounds, ketone compounds, alcohol compounds, phenol compounds and ester compounds.

[0067] In the present invention, the aldehyde compound may be at least one of an aliphatic aldehyde having 7 or more carbon atoms and an aromatic aldehyde having 6 or more carbon atoms. In a preferred embodiment, the aldehyde compound is at least one of a C7-C13 aliphatic aldehyde and a C6-C13 aromatic aldehyde. Specifically, the aldehyde compound is selected from at least one of p-methylbenzaldehyde, decanal, o-carboxybenzaldehyde, p-isopropylbenzaldehyde, cinnamaldehyde, p-hydroxybenzaldehyde, p-methoxybenzaldehyde, 2-methyl-3-(3,4-methylenedioxyphenyl)propanal, 3,4-methylenedioxybenzaldehyde, 3-(4-isopropylphenyl)-2-methylpropanal, ethyl vanillin, phenylacetaldehyde, nonadiene-2,6-aldehyde, 2,6-dimethyl-2,6-octadienal, vanillin, citronellal, neral, hydroxymethylpentylcyclohexene acetal, p-diethylaminobenzaldehyde and undecenal.

[0068] In the present invention, the ketone compound may be at least one of an aliphatic ketone having 8 or more carbon atoms and an aromatic ketone having 8 or more carbon atoms. Preferably, the ketone compound is at least one of a C8-C11 aliphatic ketone and a C8-C14 aromatic ketone. Specifically, the ketone compound is selected from at least one of 6-methyl-3,5-heptadien-2-one, 2-undecanone, acetophenone, ionone, irone, methylionone, damascone, and dihydrodamascone.

[0069] In the present invention, the alcohol compound is an alcohol having more than 6 carbon atoms, preferably a C7-C15 alcohol. Specifically, the alcohol compound is at least one of cinnamyl alcohol, menthol, cis-3,7-dimethyl-2,6-octadienol, citronellol, geraniol, myrcenol, 2,6,10-trimethyl-2,6,10-dodecatrien-12-ol, lavandulol, benzyl alcohol, 2-phenylethanol, dihydromyrcenol, tetrahydrogeraniol, and nerolidol.

[0070] In the present invention, the phenolic compound is a phenol having 6 or more carbon atoms, preferably a C6-C15 phenol. Specifically, the phenolic compound is at least one of thymol, ethyl maltol, methyl maltol, 3-propenyl-6-ethoxyphenol and isoeugenol.

[0071] In the present invention, the ester compound is an ester having more than 7 carbon atoms, preferably a C8-C17 ester. Specifically, the ester compound is at least one of methyl salicylate, methyl cinnamate, ethyl cinnamate, ethyl phenylacetate, methyl phenylacetate, geranyl phenylacetate, phenylethyl phenylacetate, isoamyl phenylacetate, benzyl salicylate, p-methylbenzyl acetate, benzyl acetate, isobutyl benzoate, isoamyl salicylate, benzyl cinnamate, phenylethyl cinnamate, linalyl formate, linalyl acetate, linalyl isobutyrate, menthyl acetate, terpineol acetate, and bornyl acetate.

[0072] In the microcapsules described herein, the capsule wall preferably comprises an inner layer and an outer layer, the inner layer being a resin and the outer layer being a rubber material. In this preferred embodiment, the microcapsule material is particularly suitable for use on asphalt pavements. On the one hand, the microcapsules possess a certain strength, meeting the requirements for pavement use. On the other hand, the rubber material, serving as the outer capsule wall, effectively blends with asphalt and has excellent adhesion, forming a strong bond with the resin (particularly melamine resin) serving as the inner capsule wall. This effectively increases the probability of material rupture when cracks appear in the asphalt pavement. Tearing of the outer capsule wall drives the tearing of the inner capsule wall, releasing the repair agent and achieving self-healing.

[0073] Further preferably, the mass ratio of the inner layer to the outer layer is 2.4-5:1, specifically, for example, it can be 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1 or 5:1.

[0074] In the present invention, the content of the capsule core, the content of the capsule wall, and the mass of the inner layer and the outer layer of the capsule wall of the microcapsule are detected by the following method: the microcapsules are added to a volatile solvent (the volatile solvent can be selected from one or more of carbon tetrachloride, dichloromethane and trichloroethylene), fully dissolved and filtered, and the obtained first solid powder is fully dried, and the difference between the mass of the obtained first solid powder and the mass of the initial microcapsule is the mass of the capsule wall outer layer; the obtained first solid powder is further fully ground, added to toluene, fully dissolved and filtered, and the obtained second solid powder is fully dried, and the difference between the mass of the obtained second solid powder and the mass of the first solid powder is the mass of the capsule core; the mass of the capsule wall inner layer is the mass of the microcapsule minus the mass of the capsule wall outer layer and the mass of the capsule core.

[0075] In the present invention, the resin may be at least one of melamine resin, urea-formaldehyde resin and polymethyl methacrylate, and is most preferably melamine resin.

[0076] In the present invention, the rubber material may be at least one of chlorinated rubber, styrene-butadiene rubber and chloroprene rubber.

[0077] In some specific embodiments of the present invention, the microcapsule includes a capsule core and a capsule wall, wherein the capsule core is wrapped in the capsule wall, and the capsule core contains an active component. The elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0078] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0079] The thickness of the capsule wall is 0.5-5 μm. Based on the total weight of the microcapsule, the content of the capsule core can be 27-53 wt.%, and the content of the capsule wall can be 47-73 wt.%.

[0080] In other specific embodiments of the present invention, the microcapsule includes a capsule core and a capsule wall, wherein the capsule core is wrapped in the capsule wall, and the capsule core contains an active component. The elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0081] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0082] The thickness of the capsule wall is 0.5-5 μm. Based on the total weight of the microcapsule, the content of the capsule core can be 27-53 wt.%, and the content of the capsule wall can be 47-73 wt.%.

[0083] The active component is a repair agent for self-repair of pavement cracks and / or an inhibitor for suppressing the release of asphalt smoke;

[0084] The bladder wall comprises an inner layer and an outer layer, the inner layer is made of resin, the outer layer is made of rubber material, and the mass ratio of the inner layer to the outer layer is 2.4-5:1.

[0085] In other specific embodiments of the present invention, the microcapsule includes a capsule core and a capsule wall, wherein the capsule core is wrapped in the capsule wall, and the capsule core contains an active component. The elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0086] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0087] The thickness of the capsule wall is 0.5-5 μm. Based on the total weight of the microcapsule, the content of the capsule core can be 30-40 wt.%, and the content of the capsule wall can be 60-70 wt.%.

[0088] The active component is a repair agent (such as an aromatics-rich component) for self-repair of pavement cracks;

[0089] The bladder wall comprises an inner layer and an outer layer, the inner layer is made of melamine resin, the outer layer is made of rubber material, and the mass ratio of the inner layer to the outer layer is 2.4-5:1.

[0090] In other specific embodiments of the present invention, the microcapsule includes a capsule core and a capsule wall, the capsule core is wrapped in the capsule wall, the capsule core contains an active component, and the elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0091] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0092] The thickness of the capsule wall is 0.5-1.5 μm;

[0093] The active component is an inhibitor for inhibiting the release of asphalt smoke (such as an aldehyde compound, a ketone compound, an alcohol compound, a phenol compound or an ester compound);

[0094] The bladder wall comprises an inner layer and an outer layer, the inner layer is melamine resin, and the outer layer is rubber material;

[0095] The mass ratio of the capsule core, the inner layer and the outer layer is 1:0.7-1:0.2-0.3.

[0096] In other specific embodiments of the present invention, the microcapsule includes a capsule core and a capsule wall, the capsule core is wrapped in the capsule wall, the capsule core contains an active component, and the elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0097] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0098] The thickness of the capsule wall is 2.1-3 μm;

[0099] The active component is an inhibitor for inhibiting the release of asphalt smoke (such as an aldehyde compound, a ketone compound, an alcohol compound, a phenol compound or an ester compound);

[0100] The bladder wall comprises an inner layer and an outer layer, the inner layer is melamine resin, and the outer layer is rubber material;

[0101] The mass ratio of the capsule core, the inner layer and the outer layer is 1:1.2-1.5:0.4-0.5.

[0102] In other specific embodiments of the present invention, the microcapsule includes a capsule core and a capsule wall, the capsule core is wrapped in the capsule wall, the capsule core contains an active component, and the elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y = 0.42X 2 -0.92X+T

[0103] Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1;

[0104] The thickness of the capsule wall is 3.1-5 μm;

[0105] The active component is an inhibitor for inhibiting the release of asphalt smoke (such as an aldehyde compound, a ketone compound, an alcohol compound, a phenol compound or an ester compound);

[0106] The bladder wall comprises an inner layer and an outer layer, the inner layer is melamine resin, and the outer layer is rubber material;

[0107] The mass ratio of the capsule core, the inner layer and the outer layer is 1:1.7-2:0.6-0.7.

[0108] The present invention also provides a method for preparing microcapsules, which comprises:

[0109] (1) mixing the active ingredient, emulsifier and water to form an oil-in-water emulsion;

[0110] (2) reacting the oil-in-water emulsion with a resin prepolymer, and then filtering, washing, and drying to obtain a pre-coated material;

[0111] (3) In the presence of a volatile solvent, the rubber material and the pre-coated material are mixed, and then the obtained mixture is mixed with water, and the temperature is raised until the volatile solvent evaporates to obtain microcapsules.

[0112] In step (1), the mixing process can be carried out in a shearing machine, and the operating conditions may include: a rotation speed of 2000-4000 r / min and a time of 20-30 min.

[0113] In step (1), the mass ratio of the active component, the emulsifier and water can be 1: (0.05-0.09): (6-9).

[0114] In some embodiments, the operation process of step (1) is: dissolving the active ingredient in water, then adding the emulsifier, and then performing high-speed shear emulsification at a rotation speed of 2000-4000 r / min.

[0115] In step (2), before the oil-in-water emulsion reacts with the resin prepolymer, the pH of the oil-in-water emulsion is adjusted to below 5, preferably 2 to 4. The reagent used to adjust the pH value can be a conventional inorganic acid solution, such as dilute hydrochloric acid.

[0116] In step (2), the reaction of the oil-in-water emulsion and the resin prepolymer is carried out under stirring. The stirring speed may be 400-800 r / min, the reaction temperature may be 60-90° C., and the reaction time may be 1-5 h.

[0117] In step (2), the filtration process may be suction filtration.

[0118] In step (2), the washing process may include washing with water and ethanol twice or more respectively.

[0119] In step (2), the drying process can be carried out in an oven, the drying temperature can be 60-90° C., and the drying time can be 5-10 hours.

[0120] In step (2), the resin prepolymer may be one or more of a melamine resin prepolymer, a urea-formaldehyde resin prepolymer, and a polymethyl methacrylate prepolymer. Preferably, the resin prepolymer is a melamine resin prepolymer. The preparation method of the melamine resin prepolymer may include: mixing and dissolving melamine and formaldehyde solution with water, adjusting the pH value to 7.5-9.5, and then placing the mixture in a constant temperature water bath at 60-90°C and reacting for 0.5-3.5 hours under stirring. During the preparation of the melamine resin prepolymer, the concentration of the formaldehyde solution may be 30-40wt.%. The mass ratio of the melamine, the formaldehyde solution, and the water may be 1:(2-3):(8-10).

[0121] In step (3), the mass ratio of the rubber material, the volatile solvent and water can be 1: (10-20): (50-150).

[0122] In the method of the present invention, the active component, the resin prepolymer and the rubber material are used in such amounts that the content of the capsule core in the prepared microcapsules is 27-53 wt.%, and the content of the capsule wall is 47-73 wt.%.

[0123] In the method of the present invention, the active component can be selected from one or any combination of at least two of the group consisting of an aromatic-rich component, an aldehyde compound, a ketone compound, an alcohol compound, a phenolic compound, and an ester compound. Specifically, the aromatic-rich component, the aldehyde compound, the ketone compound, the alcohol compound, the phenolic compound, and the ester compound are selected from the same group as described above.

[0124] In the method of the present invention, the rubber material may be at least one of chlorinated rubber, styrene-butadiene rubber and chloroprene rubber.

[0125] In the method of the present invention, the emulsifier can be selected from at least one of sodium stearate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, cetyltrimethylammonium chloride, cetyltrimethylammonium bromide, cetyldimethylhydroxyethylammonium chloride, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether and hexadecane polyoxyethylene ether.

[0126] In the method of the present invention, the volatile solvent can be selected from at least one of carbon tetrachloride, dichloromethane and trichloroethylene.

[0127] The present invention also provides microcapsules prepared by the method.

[0128] The present invention also provides application of the microcapsules in road asphalt.

[0129] The microcapsules, preparation methods and applications of the present invention are further illustrated below by examples. The examples are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the scope of protection of the present invention is not limited to the following examples.

[0130] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.

[0131] Example 1

[0132] (1) After adding 1 part by weight of catalytic cracking oil slurry (aromatic content of 50 wt.%) to 9 parts by weight of water at 60°C, 0.05 parts by weight of cetyltrimethylammonium bromide was added, and shearing and emulsification were carried out using a shearing machine at 2000 r / min for 30 minutes to form an oil-in-water emulsion in the aqueous phase.

[0133] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 8 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8.5. The flask was then placed in a constant temperature water bath at 60° C. and stirred at 800 rpm for 0.5 h to obtain a melamine resin prepolymer.

[0134] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 2, and 0.18 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 700 r / min, and reacted at 75°C for 2 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 60°C for 10 hours to obtain a pre-coated material.

[0135] (3) 0.21 parts by weight of chlorinated rubber was dissolved in 1 part by weight of dichloromethane, and 1 part by weight of the pre-coating material was added and thoroughly stirred. The resulting mixture was added to water and stirred at 500 rpm. The temperature was raised until the solvent evaporated, yielding microcapsules A1 having a size of 7-9 μm, as shown in the SEM image of FIG1 . Testing revealed that the core content of the microcapsules was 30 wt.%, the wall content was 70 wt.%, and the mass ratio of the inner layer to the outer layer of the wall was 3.1:1.

[0136] The elastic modulus of the microcapsule A1 was measured to be 2.4 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A1 was measured to be 3.2 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0137] Example 2

[0138] (1) After adding 1 part by weight of waste lubricating oil (aromatic content of 52 wt.%) to 7 parts by weight of water at 60°C, 0.06 parts by weight of nonylphenol polyoxyethylene ether was added, and shearing and emulsification were carried out using a shearing machine at 2500 r / min for 25 minutes to form an oil-in-water emulsion in the aqueous phase.

[0139] (2) 1 part by weight of melamine, 3 parts by weight of a 37 wt.% formaldehyde solution, and 10 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 7.5. The flask was then placed in a constant temperature water bath at 80°C and stirred at 600 r / min for 1 hour to obtain a melamine resin prepolymer.

[0140] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 4, and 0.13 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 600 r / min, and reacted at 70°C for 3 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven to dry at 70°C for 8 hours to obtain a pre-coated material.

[0141] (3) Dissolve 0.15 parts by weight of chloroprene rubber in 3 parts by weight of carbon tetrachloride, add 1 part by weight of the pre-coating material, and stir thoroughly. Add the resulting mixture to water, stir at 600 rpm, and increase the temperature until the solvent evaporates to obtain microcapsules A2 with a size of 4-6 μm. Testing revealed that the core content of the microcapsules was 43 wt.%, the wall content was 57 wt.%, and the mass ratio of the inner layer to the outer layer of the wall was 3.4:1.

[0142] The elastic modulus of the microcapsule A2 was measured to be 0.7 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A2 was measured to be 1.5 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0143] Example 3

[0144] (1) After adding 1 part by weight of furfural extracted oil (aromatic content of 53 wt.%) to 7 parts by weight of water at 60°C, 0.09 parts by weight of octylphenol polyoxyethylene ether was added, and shearing and emulsification were carried out at 3000 r / min using a shearing machine for 20 minutes to form an oil-in-water emulsion in the aqueous phase.

[0145] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 9 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8. The flask was then placed in a constant temperature water bath at 70°C and stirred at 500 rpm for 2 hours to obtain a melamine resin prepolymer.

[0146] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 3, and 0.12 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 500 r / min, and reacted at 65°C for 3 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 90°C for 6 hours to obtain a pre-coated material.

[0147] (3) 0.2 parts by weight of styrene-butadiene rubber was dissolved in 3 parts by weight of dichloromethane, and 1 part by weight of the pre-coating material was added and thoroughly stirred. The resulting mixture was added to water and stirred at 700 rpm. The temperature was raised until the solvent evaporated, thereby obtaining microcapsules A3 having a size of 4-6 μm. Testing revealed that the core content of the microcapsules was 43 wt.%, the wall content was 57 wt.%, and the mass ratio of the inner layer to the outer layer of the wall was 2.4:1.

[0148] The elastic modulus of the microcapsule A3 was measured to be 0.6 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A3 was measured to be 1.4 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0149] Example 4

[0150] (1) 1 part by weight of furfural extracted oil (aromatic content: 55 wt.%) was added to 6 parts by weight of water at 60°C, and then 0.06 parts by weight of sodium dodecylbenzenesulfonate was added. The mixture was sheared and emulsified at 4000 r / min for 20 minutes to form an oil-in-water emulsion in the aqueous phase.

[0151] (2) 1 part by weight of melamine, 3 parts by weight of a 37 wt.% formaldehyde solution, and 9 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 7.5. The flask was then placed in a constant temperature water bath at 60° C. and stirred at 700 rpm for 2 h to obtain a melamine resin prepolymer.

[0152] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 3, and 0.11 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 500 r / min, and reacted at 60°C for 5 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 90°C for 6 hours to obtain a pre-coated material.

[0153] (3) Dissolve 0.16 parts by weight of chlorinated rubber in 1.7 parts by weight of dichloromethane, add 1 part by weight of the pre-coating material, and stir thoroughly. Add the resulting mixture to water, stir at 800 r / min, and increase the temperature until the solvent evaporates, so that the chlorinated rubber gradually forms a film and adheres to the outer wall of the inner wall coating repair material, thereby obtaining microcapsules A4 with a size of 3-5 μm. Detection revealed that the content of the capsule core in the microcapsules was 49 wt.%, the content of the capsule wall was 51 wt.%, and the mass ratio of the inner layer to the outer layer in the capsule wall was 2.7:1.

[0154] The elastic modulus of the microcapsule A4 was measured to be 0.5 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A4 was measured to be 0.7 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0155] Example 5

[0156] (1) 1 part by weight of oil extracted from the fourth-line extraction (aromatic content of 56 wt.%) was added to 6 parts by weight of water at 60°C, and then 0.08 parts by weight of hexadecyltrimethylammonium chloride was added. The mixture was sheared and emulsified at 3000 r / min for 30 minutes to form an oil-in-water emulsion in the aqueous phase.

[0157] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 9 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8. The flask was then placed in a constant temperature water bath at 90° C. and stirred at 400 rpm for 3.5 hours to obtain a melamine resin prepolymer.

[0158] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 2, and 0.12 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 800 r / min, and reacted at 90°C for 1 hour. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 60°C for 9 hours to obtain a pre-coated material.

[0159] (3) Dissolve 0.18 parts by weight of chlorinated rubber in 5 parts by weight of dichloromethane, add 1 part by weight of the pre-coating material, and stir thoroughly. Add the resulting mixture to water, stir at 700 r / min, and increase the temperature until the solvent evaporates, so that the chlorinated rubber gradually forms a film and adheres to the outer wall of the inner wall coating repair material, thereby obtaining microcapsules A5 with a size of 3-6 μm. Testing revealed that the content of the capsule core in the microcapsules was 46 wt.%, the content of the capsule wall was 54 wt.%, and the mass ratio of the inner layer to the outer layer in the capsule wall was 2.5:1.

[0160] The elastic modulus of the microcapsule A5 was measured to be 0.6 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A5 was measured to be 1.0 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0161] Example 6

[0162] Microcapsules were prepared according to the method of Example 1, except that urea-formaldehyde resin prepolymer was used instead of melamine resin prepolymer. The urea-formaldehyde resin prepolymer was prepared by thoroughly dissolving 1 part by weight of urea, 2 parts by weight of a 37 wt.% formaldehyde solution, and 8 parts by weight of deionized water in a three-necked flask. The pH was adjusted to 9, and the mixture was then placed in a constant-temperature water bath at 60°C and stirred at 800 rpm for 0.5 h to obtain the urea-formaldehyde resin prepolymer. Microcapsules A6 were thus obtained, with a size of 6-9 μm. Testing revealed that the core content of the microcapsules was 30 wt.%, the wall content was 70 wt.%, and the mass ratio of the inner layer to the outer layer of the wall was 3.1:1.

[0163] The elastic modulus of the microcapsule A6 was measured to be 2.1 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A6 was measured to be 3.1 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X2 -0.92X+T.

[0164] Comparative Example 1

[0165] (1) After adding 1 part by weight of catalytic cracking oil slurry (aromatic content of 50 wt.%) to 9 parts by weight of water at 60°C, 0.05 parts by weight of cetyltrimethylammonium bromide was added, and shearing and emulsification were carried out using a shearing machine at 2000 r / min for 30 minutes to form an oil-in-water emulsion in the aqueous phase.

[0166] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 8 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8.5. The flask was then placed in a constant temperature water bath at 60° C. and stirred at 800 rpm for 0.5 h to obtain a melamine resin prepolymer.

[0167] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 2. 0.18 part by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 700 r / min, and reacted at 75°C for 2 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and dried in an oven at 60°C for 10 hours. The prepared product was used as microcapsule D1 with a size of 5-7 μm.

[0168] The elastic modulus of the microcapsule D1 was measured to be 2.7 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule D1 was measured to be 2.2 μm by a scanning electron microscope on a frozen section of the microcapsule, which does not conform to the calculation formula Y=0.42X 2 -0.92X+T.

[0169] Comparative Example 2

[0170] (1) After adding 1 part by weight of catalytic cracking oil slurry (aromatic content of 50 wt.%) to 9 parts by weight of water at 60°C, 0.05 parts by weight of cetyltrimethylammonium bromide was added, and shearing and emulsification were carried out using a shearing machine at 2000 r / min for 30 minutes to form an oil-in-water emulsion in the aqueous phase.

[0171] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 8 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8.5. The flask was then placed in a constant temperature water bath at 60° C. and stirred at 800 rpm for 0.5 h to obtain a melamine resin prepolymer.

[0172] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 2, and 0.18 part by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 700 r / min, and reacted at 75°C for 2 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 60°C for 10 hours to obtain a pre-coated material.

[0173] (3) 0.1 parts by weight of chlorinated rubber and 1 part by weight of the pre-coated material were directly added to water, stirred at 500 r / min, and dried to obtain microcapsules D2 having a size of 8-10 μm. In this microcapsule, the chlorinated rubber was not wrapped in the outermost layer of the microcapsule in the form of a membrane.

[0174] The elastic modulus of the microcapsule D2 was measured to be 2.6 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule D2 was measured to be 4.1 μm by a scanning electron microscope on a frozen section of the microcapsule, which does not conform to the calculation formula Y=0.42X 2 -0.92X+T.

[0175] Test Example 1

[0176] The microcapsules prepared in Examples 1-6 and Comparative Examples 1-2 were used for testing.

[0177] Donghai No. 70 asphalt was used, and 0.4 wt.% of microcapsules were added. Referring to the ductility test method in JTG E20-2011 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering", the specimen was cut in the middle and left for 24 hours. The ductility change before and after the test was tested, and the healing rate was calculated. The results are shown in Table 1.

[0178] Healing rate = elongation 24 hours after cutting / elongation before cutting

[0179] Table 1: Ductility test results of asphalt samples

[0180] It can be seen from the results in Table 1 that the use of the microcapsules of the present invention and the selection of a repair agent for self-repair of pavement cracks as an active component can effectively improve the self-repair efficiency of pavement asphalt materials.

[0181] Example 7

[0182] (1) After adding 1 part by weight of p-anisaldehyde to 9 parts by weight of water at 60° C., 0.05 parts by weight of cetyltrimethylammonium bromide was added, and the mixture was sheared and emulsified at 2000 r / min for 30 minutes to form an oil-in-water emulsion in the aqueous phase.

[0183] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 8 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8.5. The flask was then placed in a constant temperature water bath at 60° C. and stirred at 800 rpm for 0.5 h to obtain a melamine resin prepolymer.

[0184] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 2, and 0.18 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 700 r / min, and reacted at 75°C for 2 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 60°C for 10 hours to obtain a pre-coated material.

[0185] (3) Dissolve 0.21 parts by weight of chlorinated rubber in 1 part by weight of dichloromethane, add 1 part by weight of the pre-coating material, and stir thoroughly. Add the resulting mixture to water, stir at 500 rpm, and increase the temperature until the solvent evaporates, to produce microcapsules A7 with a size of 7-9 μm. Testing revealed that the core content of the microcapsules was 30 wt.%, the wall content was 70 wt.%, and the mass ratio of the inner layer to the outer layer of the wall was 3.1:1.

[0186] The elastic modulus of the microcapsule A7 was measured to be 2.1 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A7 was measured to be 3.0 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0187] Example 8

[0188] (1) After adding 1 part by weight of acetophenone to 7 parts by weight of water at 60° C., 0.06 parts by weight of nonylphenol polyoxyethylene ether was added, and the mixture was sheared and emulsified at 2500 r / min for 25 minutes to form an oil-in-water emulsion in the aqueous phase.

[0189] (2) 1 part by weight of melamine, 3 parts by weight of a 37 wt.% formaldehyde solution, and 10 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 7.5. The flask was then placed in a constant temperature water bath at 80°C and stirred at 600 r / min for 1 hour to obtain a melamine resin prepolymer.

[0190] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 4, and 0.13 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 600 r / min, and reacted at 70°C for 3 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven to dry at 70°C for 8 hours to obtain a pre-coated material.

[0191] (3) Dissolve 0.15 parts by weight of chloroprene rubber in 3 parts by weight of carbon tetrachloride, add 1 part by weight of the pre-coating material, and stir thoroughly. Add the resulting mixture to water, stir at 600 rpm, and increase the temperature until the solvent evaporates to obtain microcapsules A8 with a size of 4-6 μm. Testing revealed that the core content of the microcapsules was 43 wt.%, the wall content was 57 wt.%, and the mass ratio of the inner layer to the outer layer of the wall was 3.4:1.

[0192] The elastic modulus of the microcapsule A8 was measured to be 0.6 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A8 was measured to be 1.4 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0193] Example 9

[0194] (1) After adding 1 part by weight of benzyl alcohol to 7 parts by weight of water at 60°C, 0.09 parts by weight of octylphenol polyoxyethylene ether was added, and shearing and emulsification were carried out for 20 minutes using a shearing machine at 3000 r / min to form an oil-in-water emulsion in the aqueous phase.

[0195] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 9 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8. The flask was then placed in a constant temperature water bath at 70°C and stirred at 500 rpm for 2 hours to obtain a melamine resin prepolymer.

[0196] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 3, and 0.12 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 500 r / min, and reacted at 65°C for 3 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 90°C for 6 hours to obtain a pre-coated material.

[0197] (3) 0.2 parts by weight of styrene-butadiene rubber was dissolved in 3 parts by weight of dichloromethane, and 1 part by weight of the pre-coating material was added and thoroughly stirred. The resulting mixture was added to water and stirred at 700 rpm. The temperature was raised until the solvent evaporated, thereby obtaining microcapsules A9 having a size of 4-6 μm. Testing revealed that the core content of the microcapsules was 43 wt.%, the wall content was 57 wt.%, and the mass ratio of the inner layer to the outer layer of the wall was 2.4:1.

[0198] The elastic modulus of the microcapsule A9 was measured to be 0.5 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A9 was measured to be 1.2 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0199] Example 10

[0200] (1) After adding 1 part by weight of 3-propenyl-6-ethoxyphenol to 6 parts by weight of water at 60°C, 0.06 parts by weight of sodium dodecylbenzenesulfonate was added, and the mixture was sheared and emulsified at 4000 r / min for 20 minutes to form an oil-in-water emulsion in the aqueous phase.

[0201] (2) 1 part by weight of melamine, 3 parts by weight of a 37 wt.% formaldehyde solution, and 9 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 7.5. The flask was then placed in a constant temperature water bath at 60° C. and stirred at 700 rpm for 2 h to obtain a melamine resin prepolymer.

[0202] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 3, and 0.11 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 500 r / min, and reacted at 60°C for 5 hours. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 90°C for 6 hours to obtain a pre-coated material.

[0203] (3) Dissolve 0.16 parts by weight of chlorinated rubber in 1.7 parts by weight of dichloromethane, add 1 part by weight of the pre-coating material, and stir thoroughly. Add the resulting mixture to water, stir at 800 r / min, and increase the temperature until the solvent evaporates, so that the chlorinated rubber gradually forms a film and adheres to the outer wall of the inner wall coating repair material, thereby obtaining microcapsules A10 with a size of 3-5 μm. Detection revealed that the content of the capsule core in the microcapsules was 49 wt.%, the content of the capsule wall was 51 wt.%, and the mass ratio of the inner layer to the outer layer in the capsule wall was 2.7:1.

[0204] The elastic modulus of the microcapsule A10 was measured to be 0.4 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A10 was measured to be 0.8 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0205] Example 11

[0206] (1) After adding 1 part by weight of phenylethyl phenylacetate to 6 parts by weight of water at 60°C, 0.08 parts by weight of hexadecyltrimethylammonium chloride was added, and the mixture was sheared and emulsified at 3000 r / min for 30 minutes to form an oil-in-water emulsion in the aqueous phase.

[0207] (2) 1 part by weight of melamine, 2 parts by weight of a 37 wt.% formaldehyde solution, and 9 parts by weight of deionized water were fully dissolved in a three-necked flask, and the pH value was adjusted to 8. The flask was then placed in a constant temperature water bath at 90° C. and stirred at 400 rpm for 3.5 hours to obtain a melamine resin prepolymer.

[0208] Dilute hydrochloric acid was added dropwise to 1 part by weight of the oil-in-water emulsion to adjust the pH value to 2, and 0.12 parts by weight of the prepared melamine resin prepolymer was slowly added dropwise to the oil-in-water emulsion, stirred at 800 r / min, and reacted at 90°C for 1 hour. After the reaction, the obtained mixed solution was filtered, washed twice with water and ethanol respectively, and placed in an oven at 60°C for 9 hours to obtain a pre-coated material.

[0209] (3) Dissolve 0.18 parts by weight of chlorinated rubber in 5 parts by weight of dichloromethane, add 1 part by weight of the pre-coating material, and stir thoroughly. Add the resulting mixture to water, stir at 700 r / min, and increase the temperature until the solvent evaporates, so that the chlorinated rubber gradually forms a film and adheres to the outer wall of the inner wall coating repair material, thereby obtaining microcapsules A11 with a size of 3-6 μm. Detection revealed that the content of the capsule core in the microcapsules was 46 wt.%, the content of the capsule wall was 54 wt.%, and the mass ratio of the inner layer to the outer layer in the capsule wall was 2.5:1.

[0210] The elastic modulus of the microcapsule A11 was measured to be 0.5 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A11 was measured to be 0.9 μm by a scanning electron microscope on a frozen section of the microcapsule, which is consistent with the calculation formula Y=0.42X 2 -0.92X+T.

[0211] Comparative Example 3

[0212] Microcapsules were prepared according to the method of Example 7, except that in step (1), the amount of water was increased to 15 parts by weight and the amount of chlorinated rubber was increased to 0.25 parts by weight. Finally, capsules D3 were obtained, with a size of 6-8 μm.

[0213] The elastic modulus of the microcapsule D3 was measured to be 3.3 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule D3 was measured to be 3.5 μm by a scanning electron microscope on a frozen section of the microcapsule, which does not conform to the calculation formula Y=0.42X 2 -0.92X+T.

[0214] Comparative Example 4

[0215] Microcapsules were prepared according to the method of Example 7, except that in step (3), the amount of chlorinated rubber was reduced to 0.11 parts by weight and the amount of melamine resin prepolymer was increased to 0.23 parts by weight. Finally, capsules D4 were obtained, with a size of 5-7 μm.

[0216] The elastic modulus of the microcapsule A6 was measured to be 2.6 GPa by a nanoindenter, and the thickness of the capsule wall of the microcapsule A6 was measured to be 2.9 μm by a scanning electron microscope on a frozen section of the microcapsule, which does not conform to the calculation formula Y=0.42X 2 -0.92X+T.

[0217] Test Example 2

[0218] The microcapsules prepared in Examples 7-11 and Comparative Examples 3-4 were used for testing.

[0219] Donghai No. 70 asphalt was used, 0.4 wt.% of microcapsules were added, and the asphalt flue gas was enriched under the condition of heating at 163°C for 6 hours. The asphalt flue gas was tested and analyzed by gas chromatography and total hydrocarbon analyzer. The results are shown in Table 2.

[0220] Table 2: Asphalt smoke test results

[0221] It can be seen from the results in Table 2 that the use of the microcapsules of the present invention and the selection of an inhibitor for inhibiting the release of asphalt fume as an active component can effectively reduce the emission of asphalt fume and reduce pollution to the environment.

[0222] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A microcapsule, characterized in that: The microcapsule comprises a capsule core and a capsule wall, wherein the capsule core is wrapped in the capsule wall, the capsule core contains active components, and the elastic modulus of the microcapsule and the thickness of the capsule wall satisfy the following formula: Y=0.42X 2 -0.92X+T Wherein, Y is the elastic modulus of the microcapsule, in GPa; X is the thickness of the capsule wall, in μm; T is 1±0.1; The elastic modulus of the microcapsule is obtained by testing the mechanical properties of the microcapsule using a nanoindenter, and the thickness of the capsule wall is obtained by testing the frozen sections of the microcapsule using a scanning electron microscope.

2. The microcapsule according to claim 1, characterized in that Based on the total weight of the microcapsule, the content of the capsule core is 27-53wt.%, and the content of the capsule wall is 47-73wt.%.

3. The microcapsule according to claim 1 or 2, characterized in that The active component is a repairing agent for self-repairing of road cracks and / or an inhibitor for inhibiting the release of asphalt smoke.

4. The microcapsule according to claim 3, characterized in that The repairing agent for self-repair of road cracks is rich in aromatic hydrocarbon components; Preferably, the aromatics-rich component is selected from at least one of catalytic cracking slurry, oil extracted from a four-line reduction reactor, furfural extracted oil and waste lubricating oil; Preferably, the aromatic content of the aromatic-rich component is 45-65 wt.%.

5. The microcapsule according to claim 3, characterized in that The inhibitor for inhibiting the release of asphalt smoke is at least one of aldehyde compounds, ketone compounds, alcohol compounds, phenol compounds and ester compounds; Preferably, the aldehyde compound is selected from aliphatic aldehydes having carbon atoms of 7 or more and aromatic aldehydes having carbon atoms of 6 or more, more preferably p-tolualdehyde, decanal, o-carboxybenzaldehyde, p-isopropylbenzaldehyde, cinnamaldehyde, p-hydroxybenzaldehyde, p-methoxybenzaldehyde, 2-methyl-3-(3,4-methylene-dioxyphenyl)propanal, 3,4-methylenedioxybenzaldehyde, 3-(4-isopropylphenyl)-2-methylpropanal, ethyl vanillin, phenylacetaldehyde, anisaldehyde, nonadiene-2,6-aldehyde, 2,6-dimethyl-2,6-octadienal, vanillin, citronellal, neral, hydroxymethylpentylcyclohexene acetal, p-diethylaminobenzaldehyde and undecenal. At least one; Preferably, the ketone compound is selected from aliphatic ketones having carbon atoms greater than or equal to 8 and aromatic ketones having carbon atoms greater than or equal to 8, more preferably at least one of 6-methyl-3,5-heptadien-2-one, 2-undecanone, acetophenone, ionone, irone, methylionone, damascenone and dihydrodamascenone; Preferably, the alcohol compound is an alcohol having more than 6 carbon atoms, more preferably at least one of cinnamyl alcohol, menthol, cis-3,7-dimethyl-2,6-octadienol, citronellol, geraniol, myrcenol, 2,6,10-trimethyl-2,6,10-dodecatrien-12-ol, lavandulol, benzylenol, 2-phenylethanol, dihydromyrcenol, tetrahydrogeraniol and nerolidol; Preferably, the phenolic compound is a phenol having 6 or more carbon atoms, more preferably at least one of thymol, ethyl maltol, methyl maltol, 3-propenyl-6-ethoxyphenol and isoeugenol; Preferably, the ester compound is an ester having a carbon number greater than 7, more preferably at least one of methyl salicylate, methyl cinnamate, ethyl cinnamate, ethyl phenylacetate, methyl phenylacetate, geranyl phenylacetate, phenylethyl phenylacetate, isoamyl phenylacetate, benzyl salicylate, p-methylbenzyl acetate, benzyl acetate, isobutyl benzoate, isoamyl salicylate, benzyl cinnamate, phenylethyl cinnamate, linalyl formate, linalyl acetate, linalyl isobutyrate, menthyl acetate, pine acetate and bornyl acetate.

6. The microcapsule according to any one of claims 1 to 5, characterized in that The thickness of the capsule wall is 0.5-5 μm.

7. The microcapsule according to any one of claims 1 to 6, characterized in that The bladder wall comprises an inner layer and an outer layer, the inner layer is a resin, and the outer layer is a rubber material; Preferably, the mass ratio of the inner layer to the outer layer is 2.4-5:

1.

8. The microcapsule according to claim 7, characterized in that The resin is at least one of melamine resin, urea-formaldehyde resin and polymethyl methacrylate, preferably melamine resin.

9. The microcapsule according to claim 7, characterized in that The rubber material is at least one of chlorinated rubber, styrene-butadiene rubber and chloroprene rubber.

10. The microcapsule according to any one of claims 1 to 9, characterized in that The size of the microcapsule is less than 50 μm, preferably less than 20 μm, and more preferably 3-15 μm.

11. A method for preparing microcapsules, characterized in that: The method includes: (1) mixing the active ingredient, emulsifier and water to form an oil-in-water emulsion; (2) reacting the oil-in-water emulsion with a resin prepolymer, and then filtering, washing, and drying to obtain a pre-coated material; (3) In the presence of a volatile solvent, the rubber material and the pre-coated material are mixed, and then the obtained mixture is mixed with water, and the temperature is raised until the volatile solvent evaporates to obtain microcapsules.

12. The method according to claim 11, characterized in that In step (1), the mass ratio of the active component, the emulsifier and water is 1:(0.05-0.09):(6-9).

13. The method according to claim 11, characterized in that In step (2), before the oil-in-water emulsion reacts with the resin prepolymer, the pH value of the oil-in-water emulsion is adjusted to below 5, preferably 2-4.

14. The method according to claim 11 or 13, characterized in that In step (2), the resin prepolymer is a melamine resin prepolymer; Preferably, the preparation method of the melamine resin prepolymer comprises: mixing and dissolving melamine and formaldehyde solution with water, adjusting the pH value to 7.5-9.5, and then placing in a constant temperature water bath at 60-90° C., and reacting for 0.5-3.5 hours under stirring; Preferably, the concentration of the formaldehyde solution is 30-40wt.%; Preferably, the mass ratio of the melamine, the formaldehyde solution and the water is 1:(2-3):(8-10).

15. The method according to claim 11, characterized in that In step (3), the mass ratio of the rubber material, the volatile solvent and water is 1:(10-20):(50-150).

16. The method according to any one of claims 11 to 15, characterized in that: The active component is one or any combination of at least two or more of an aromatic hydrocarbon-rich component, an aldehyde compound, a ketone compound, an alcohol compound, a phenol compound and an ester compound.

17. The method according to any one of claims 11 to 16, characterized in that: The rubber material is at least one of chlorinated rubber, styrene-butadiene rubber and chloroprene rubber.

18. The method according to any one of claims 11 to 16, characterized in that: The emulsifier is selected from at least one of sodium stearate, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, hexadecyldimethylhydroxyethylammonium chloride, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether and hexadecane polyoxyethylene ether.

19. The method according to any one of claims 11 to 16, characterized in that: The volatile solvent is selected from at least one of carbon tetrachloride, dichloromethane and trichloroethylene.

20. Microcapsules prepared by the method of any one of claims 11 to 19.

21. Use of the microcapsules according to any one of claims 1 to 10 and 20 in road asphalt.

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