Asphalt emulsion

Abstract

To provide an asphalt emulsion that has good emulsifiability and workability.SOLUTION: The asphalt emulsion contains an emulsion particle in an aqueous phase, the emulsion particle has an asphalt particle and a closed vesicle formed with amphipathic substance that spontaneously forms closed vesicle and / or a particle of polycondensation polymer having hydroxyl group, the surface of the asphalt particle is covered with the closed vesicle and / or the polycondensation polymer particle, and the viscosity of the asphalt particle at 160°C is 20 mPa-s or more and 1580 mPa-s or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an asphalt emulsion. [Background technology]

[0002] Conventionally, asphalt emulsions are emulsified by adding a surfactant to asphalt. However, the type of surfactant suitable for emulsifying asphalt varies depending on the type of asphalt, which is the oil phase. Therefore, in asphalt emulsions emulsified with such surfactants (hereinafter also referred to as surfactant-type asphalt emulsions), it is necessary to select the surfactant according to the type of asphalt and the type of emulsion to be produced. Furthermore, in surfactant-type asphalt emulsions, the emulsifying effect of the surfactant decreases over time, and the emulsified asphalt may separate from the water phase.

[0003] In recent years, an emulsification method using a three-phase emulsification method that solves such problems is described in Patent Document 1. The O / W type emulsion described in Patent Document 1 contains an oil phase that is a liquid having a viscosity of 3000 mPa s or more at 25°C and / or a semi-solid at 25°C and / or a solid at 25°C, an aqueous phase, and polycondensation polymer particles having hydroxyl groups and / or closed vesicles formed by an amphiphilic substance that forms closed vesicles. The polycondensation polymer particles and / or closed vesicles are present at the interface between the oil phase and the aqueous phase. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-026708 A Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 describes an asphalt emulsion produced by an emulsification method using a three-phase emulsification method. However, Patent Document 1 aims to provide an emulsion that is fluid at room temperature while containing a highly viscous liquid, semi-solid or solid oil at room temperature. Therefore, the asphalt emulsion of Patent Document 1 has room for improvement in terms of workability during application such as spraying and coating.

[0006] An object of the present invention is to provide an asphalt emulsion having good emulsification properties and workability. [Means for solving the problem]

[0007] [1] An asphalt emulsion comprising emulsion particles in an aqueous phase, the emulsion particles having asphalt particles and closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having hydroxyl groups, the surfaces of the asphalt particles being covered with the closed vesicles and / or the particles of the polycondensation polymer, and the viscosity of the asphalt particles at 160°C is 20 mPa s or more and 1580 mPa s or less. [2] The asphalt emulsion described in [1] above, wherein the Engler degree of the asphalt emulsion at 25°C is 1 or more and 60 or less. [3] The asphalt emulsion according to [1] or [2] above, wherein the asphalt emulsion further contains saturated fatty acids. [4] The asphalt emulsion according to any one of the above [1] to [3], wherein the asphalt particles are soft asphalt particles. [5] The asphalt emulsion according to any one of the above [1] to [4], wherein the content of the emulsion particles in the asphalt emulsion is 1% or more and 80% or less. Effect of the Invention

[0008] According to the present invention, it is possible to provide an asphalt emulsion having good emulsifiability and workability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a detailed description will be given based on an embodiment.

[0010] An asphalt emulsion according to an embodiment contains emulsion particles in an aqueous phase, the emulsion particles having asphalt particles and closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having hydroxyl groups, the surfaces of the asphalt particles being covered with the closed vesicles and / or particles of the polycondensation polymer, and the viscosity of the asphalt particles at 160°C is 20 mPa·s or more and 1580 mPa·s or less.

[0011] In the asphalt emulsion of the embodiment, the emulsified emulsion particles are contained in the aqueous phase. The emulsion particles have asphalt particles, which are the oil phase of the asphalt emulsion, and closed vesicles (hereinafter also simply referred to as closed vesicles) formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of polycondensation polymers having hydroxyl groups (hereinafter also simply referred to as polycondensation polymer particles). Thus, the asphalt emulsion is an O / W type emulsion in which the emulsion particles are dispersed in the aqueous phase.

[0012] The surface of the asphalt particles is covered with closed vesicles and / or polycondensation polymer particles. The emulsification properties of the emulsion particles are the same whether the surface of the asphalt particles is covered only with closed vesicles, only with polycondensation polymer particles, or both. Therefore, the emulsion particles may have only closed vesicles, only polycondensation polymer particles, or both closed vesicles and polycondensation polymer particles, with respect to the particles of closed vesicles and polycondensation polymer.

[0013] When the closed vesicles and / or polycondensation polymer particles cover the surface of the asphalt particles, the emulsifying properties of the asphalt emulsion are maintained by the following mechanism.

[0014] Closed vesicles formed by amphiphilic substances that spontaneously form closed vesicles have the ability to spontaneously form closed vesicles in water. Closed vesicles and polycondensation polymer particles are known as particles with so-called three-phase emulsification ability. Since the surfaces of closed vesicles and polycondensation polymer particles are hydrophilic, closed vesicles and polycondensation polymer particles generate repulsive forces between each other. By arranging closed vesicles or polycondensation polymer particles on the surfaces of asphalt particles, that is, by covering the surfaces of asphalt particles with closed vesicles or polycondensation polymer particles, repulsive forces are generated between asphalt particles. Since such repulsive forces between asphalt particles are greater than the attractive forces generated between asphalt particles, aggregation between asphalt particles in the aqueous phase is suppressed, and the dispersibility of emulsion particles is maintained and improved.

[0015] In the three-phase emulsification method, closed vesicles or polycondensation polymer particles are present at the interface between the oil phase and the water phase and adhere to the oil phase by van der Waals forces, enabling emulsification. This three-phase emulsification mechanism is completely different from the emulsification mechanism using surfactants, which maintains the emulsified state by directing the hydrophilic and hydrophobic parts toward the water phase and oil phase, respectively, and lowering the oil-water interfacial tension (see, for example, Japanese Patent Publication No. 3855203). In the asphalt emulsion of the embodiment, as described above, the closed vesicles or polycondensation polymer particles emulsify the asphalt particles.

[0016] The amphiphilic substance is an amphiphilic substance capable of forming closed vesicles in water, for example, capable of forming a bilayer membrane in water (i.e., capable of forming a vesicle in water). As an amphiphilic substance that forms closed vesicles, a derivative of polyoxyethylene hydrogenated castor oil represented by the following formula (1), or a dialkylammonium derivative, a trialkylammonium derivative, a tetraalkylammonium derivative, a dialkenylammonium derivative, a trialkenylammonium derivative, or a halogen salt derivative of a tetraalkenylammonium derivative represented by the following formula (2) is suitable. Among them, polyoxyethylene hydrogenated castor oil is preferred.

[0017] [ka]

[0018] In the formula (1), the average number of moles of ethylene oxide added, E (E = L + M + N + X + Y + Z), is preferably 3 or more and 100 or less.

[0019] [ka]

[0020] In formula (2), it is preferable that R1 and R2 are each independently an alkyl group or an alkenyl group having 8 to 22 carbon atoms, R3 and R4 are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and X is F, Cl, Br, or I.

[0021] In addition to the above, other suitable examples of amphipathic substances include phospholipids and phospholipid derivatives, particularly those in which a hydrophobic group and a hydrophilic group are bonded via an ester bond.

[0022] As the phospholipid, among the structures represented by the following formula (3), DLPC (1,2-Dilauroyl-sn-glycero-3-phospho-rac-1-choline) with a carbon chain length of 12, DMPC (1,2-Dimyristoyl-sn-glycero-3-phospho-rac-1-choline) with a carbon chain length of 14, and DPPC (1,2-Dipalmitoyl-sn-glycero-3-phospho-rac-1-choline) with a carbon chain length of 16 are preferred.

[0023] [ka]

[0024] Among the structures represented by the following formula (4), the Na salt or NH4 salt of DLPG (1,2-Dilauroyl-sn-glycero-3-phospho-rac-1-glycerol) having a carbon chain length of 12, the Na salt or NH4 salt of DMPG (1,2-Dimyristoyl-sn-glycero-3-phospho-rac-1-glycerol) having a carbon chain length of 14, and the Na salt or NH4 salt of DPPG (1,2-Dipalmitoyl-sn-glycero-3-phospho-rac-1-glycerol) having a carbon chain length of 16 are preferred.

[0025] [ka]

[0026] Further, suitable examples of phospholipids include lecithin such as egg yolk lecithin or soybean lecithin.

[0027] Other suitable examples of the amphiphilic substance include fatty acid esters, such as glycerin fatty acid esters, polyglycerin fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, and propylene glycol fatty acid esters.

[0028] The polyglycerol fatty acid ester is preferably an ester of a fatty acid with polyglycerol, the fatty acid being a straight-chain fatty acid or a branched fatty acid, regardless of whether the fatty acid is saturated or unsaturated. Among these, polyglyceryl monomyristate, polyglyceryl dimyristate, polyglyceryl trimyristate, polyglyceryl monopalmitate, polyglyceryl dipalmitate, polyglyceryl tripalmitate, polyglyceryl monostearate, polyglyceryl distearate, polyglyceryl tristearate, polyglyceryl monoisostearate, polyglyceryl diisostearate, polyglyceryl triisostearate, polyglyceryl monooleate, polyglyceryl dimonooleate, and polyglyceryl trimonooleate are more preferred, with decaglyceryl myristate being even more preferred.

[0029] As the sucrose fatty acid ester, sucrose laurate, sucrose myristic acid ester, sucrose palmitate, sucrose stearate, and sucrose oleate are preferred.

[0030] The polycondensation polymer constituting the polycondensation polymer particles is preferably a natural polymer or a synthetic polymer, and is appropriately selected depending on the application of the asphalt emulsion. Natural polymers are preferred because they are safe and generally inexpensive, and sugar polymers are more preferred because they have excellent emulsifying properties.

[0031] The polycondensation polymer particles include single particles of polycondensation polymer and single particles of polycondensation polymer linked together, but do not include aggregates (having a network structure) of polycondensation polymer before being made into single particles.

[0032] Sugar polymers are polymers having a glycoside structure, such as cellulose and starch. For example, preferred are those produced by microorganisms using several sugars selected from monosaccharides such as ribose, xylose, rhamnose, fucose, glucose, mannose, glucuronic acid, and gluconic acid as building blocks; natural polymers and derivatives thereof such as xanthan gum, gum arabic, guar gum, karaya gum, carrageenan, pectin, fucoidan, quince seed gum, trant gum, locust bean gum, galactomannan, curdlan, gellan gum, fucogel, casein, gelatin, starch, collagen, hyaluronic acid, hyaluronic acid derivatives, and Tremella fuciformis polysaccharide; semi-synthetic polymers such as methylcellulose, ethylcellulose, cationized cellulose, methylhydroxypropylcellulose, carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, sodium carboxymethylcellulose, propylene glycol alginate, cellulose crystals, starch-sodium acrylate graft polymers, and hydrophobized hydroxypropylmethylcellulose; and synthetic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymers, polyacrylates, and polyethylene oxide. Among these, carboxymethyl cellulose, cationic cellulose, and hydroxyethyl cellulose are more preferable.

[0033] The total amount of the closed vesicles and the polycondensation polymer particles is preferably 0.01% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.30% by mass or more, based on the total amount of the asphalt emulsion. The total amount of the closed vesicles and the polycondensation polymer particles is preferably 30% by mass or less, more preferably 10% by mass or less, and even more preferably 3% by mass or less, based on the total amount of the asphalt emulsion. When the total amount of the closed vesicles and the polycondensation polymer particles is 0.01% by mass or more, based on the total amount of the asphalt emulsion, the emulsification property of the asphalt emulsion is good, and the emulsification property is improved as the total amount of the closed vesicles and the polycondensation polymer particles increases. When the total amount of the closed vesicles and the polycondensation polymer particles is high, the asphalt emulsion can be prevented from adhering to the tires of the automobile after the asphalt emulsion is sprayed on the pavement. In other words, the tire adhesion rate of the asphalt emulsion can be reduced. On the other hand, when the total amount of the closed vesicles and the polycondensation polymer particles is about 30 mass % relative to the total amount of the asphalt emulsion, the emulsifiability of the asphalt emulsion is sufficiently good.

[0034] The total amount of closed vesicles and polycondensation polymer particles means the total amount of closed vesicles and polycondensation polymer particles that constitute emulsion particles, and does not include closed vesicles and polycondensation polymer particles that do not constitute emulsion particles.

[0035] The average particle size of the closed vesicles and polycondensation polymer particles is 8 nm to 800 nm before forming the emulsion particles, but 8 nm to 500 nm in the asphalt emulsion. The average particle size of the closed vesicles and polycondensation polymer particles is measured by dynamic light scattering using a particle size distribution analyzer FPAR (manufactured by Otsuka Electronics Co., Ltd.) and is a value obtained by Contin analysis. The method for preparing the closed vesicles and polycondensation polymer particles having an average particle size within the above range is conventionally known as a method for preparing particles with three-phase emulsification ability, as disclosed in Patent No. 3855203, etc., and is therefore omitted here for convenience.

[0036] In addition, when a light scattering measurement is performed on the mixed solution described below used for emulsifying the oily component, and the average particle size of the closed vesicles and polycondensation polymer particles present in the mixed solution is, for example, 8 nm or more and 800 nm or less, it can be determined that the closed vesicles and polycondensation polymer particles are capable of three-phase emulsification. Furthermore, the emulsion particles can be confirmed by observing the emulsion particles contained in the asphalt emulsion with an atomic force microscope (AFM) and confirming that at least one of the closed vesicles and polycondensation polymer particles is attached to the surface of the asphalt particles.

[0037] The content of emulsion particles in the asphalt emulsion is preferably 1% or more, more preferably 25% or more, and even more preferably 40% or more. The content of emulsion particles in the asphalt emulsion is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less. When the content of emulsion particles in the asphalt emulsion is within the above range, it is possible to produce an asphalt emulsion that fully meets the standards for paving emulsions, and the workability of the asphalt emulsion can be improved.

[0038] The average particle size of the asphalt particles is preferably 0.01 μm or more, more preferably 0.10 μm or more, and even more preferably 1.00 μm or more. The average particle size of the asphalt particles is preferably 1180 μm or less, more preferably 500 μm or less, and even more preferably 20 μm or less. When the average particle size of the asphalt particles is within the above range, the emulsification property of the asphalt emulsion is good. The average particle size of the asphalt particles is measured by dynamic light scattering using a particle size distribution measuring device FPAR (manufactured by Otsuka Electronics Co., Ltd.) and is a value obtained by Contin analysis.

[0039] In asphalt emulsions, the water phase is the medium that disperses the emulsion particles.

[0040] The total amount of the aqueous phase is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, based on the total amount of the asphalt emulsion. The total amount of the aqueous phase is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on the total amount of the asphalt emulsion. When the total amount of the aqueous phase is within the above range, the emulsifiability of the asphalt emulsion is good.

[0041] The viscosity of the asphalt particles contained in the asphalt emulsion at 160°C (hereinafter simply referred to as the viscosity of the asphalt particles) is 20 mPa·s or more and 1580 mPa·s or less. If the viscosity of the asphalt particles is within the above range, it meets the requirements of Japanese Industrial Standards JIS K 2208 2009 and Japan Asphalt Emulsion Association Standard JEAAS 2020 It can satisfy the Engler degree standard set forth in the .

[0042] Furthermore, when the viscosity of the asphalt particles is 20 mPa·s or more, an asphalt emulsion that meets the standards for paving emulsions can be produced, and the asphalt emulsion has good workability during application, such as spraying or coating. Furthermore, when the viscosity of the asphalt particles is 1580 mPa·s or less, the emulsification properties of the asphalt emulsion are good. From this perspective, the lower limit of the viscosity of the asphalt particles contained in the asphalt emulsion at 160°C is 20 mPa·s or more, preferably 40 mPa·s or more, and more preferably 50 mPa·s or more, and the upper limit is 1580 mPa·s or less, preferably 500 mPa·s or less, and more preferably 300 mPa·s or less.

[0043] Furthermore, the Engler degree of the asphalt emulsion at 25°C (hereinafter also simply referred to as the Engler degree of the asphalt emulsion) is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more. When the Engler degree of the asphalt emulsion is 1 or more, it is possible to suppress runoff after spraying due to the low viscosity of the asphalt emulsion. Furthermore, the Engler degree of the asphalt emulsion is preferably 60 or less, more preferably 15 or less, and even more preferably 6 or less. When the Engler degree of the asphalt emulsion is 60 or less, it is possible to suppress uneven spraying and clogging of the spray nozzle due to the excessive viscosity of the asphalt emulsion. Furthermore, when the Engler degree of the asphalt emulsion is within the above range, the workability during application such as spraying and coating of the asphalt emulsion is good.

[0044] In addition, the asphalt emulsion preferably further contains a saturated fatty acid. As the saturated fatty acid, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, arachidic acid, henicosylic acid, behenic acid, tricosylic acid, and lignoceric acid are suitable. When the asphalt emulsion contains a saturated fatty acid, the adhesion of the asphalt emulsion to the tires of a car after being sprayed on the pavement can be suppressed. In other words, the adhesion rate of the asphalt emulsion to the tires can be reduced.

[0045] The total amount of saturated fatty acids is preferably 0.01% by mass or more and 10.00% by mass or less based on the total amount of the asphalt emulsion. When the total amount of saturated fatty acids is within the above range, the adhesion rate of the asphalt emulsion to the tire can be sufficiently reduced.

[0046] Asphalt constituting the asphalt particles, petroleum asphalt produced from petroleum is suitable. Petroleum asphalt includes soft asphalt and hard asphalt. Asphalt may also be bleached asphalt. Bleached asphalt contains polymer particles (bleaching emulsion). The type of asphalt constituting the asphalt particles is appropriately selected according to the application of the asphalt emulsion.

[0047] In addition, in conventional tire adhesion inhibiting asphalt emulsions (surfactant type asphalt emulsions), hard asphalt is mainly used, and asphalt emulsions using soft asphalt have poor tire adhesion rates. On the other hand, since the asphalt emulsion of the embodiment uses a three-phase emulsification method, even if the asphalt constituting the asphalt particles is soft asphalt, that is, the asphalt particles are soft asphalt particles, it has properties such as good emulsification properties, workability, and low tire adhesion rates.

[0048] The asphalt emulsion may further contain a pH adjuster. Suitable acidic pH adjusters include acetic acid and hydrochloric acid. Suitable alkaline pH adjusters include caustic soda (sodium hydroxide).

[0049] In the embodiment, a nonionic asphalt emulsion can be produced. By including various pH adjusters in the asphalt emulsion according to the application of the asphalt emulsion, a cationic asphalt emulsion or an anionic asphalt emulsion can be easily prepared. On the other hand, since cationic asphalt emulsions (surfactant-type asphalt emulsions) are widely used in the past, adding an alkaline pH adjuster to the past asphalt emulsion will cause the asphalt emulsion to degrade. Therefore, it is not easy to prepare an anionic asphalt emulsion with the past asphalt emulsion.

[0050] The asphalt emulsion may also contain optional components to the extent that the emulsifiability and workability are not reduced. Examples of such optional components include polyhydric alcohols, glycol ethers, surfactants, liquid oils, preservatives, and other additives. The asphalt emulsion may contain one type of optional component, or may contain a combination of two or more types of optional components. The total amount of optional components contained in the asphalt emulsion is appropriately set depending on the application of the asphalt emulsion.

[0051] Such an asphalt emulsion is suitable for use as an asphalt emulsion for paving, which requires high workability.

[0052] Next, a method for producing the above-mentioned asphalt emulsion will be described.

[0053] The method for producing an asphalt emulsion includes a mixing step and an emulsification step.

[0054] In the mixing step, the closed vesicles formed by the amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having hydroxyl groups are mixed with water to obtain a mixed solution in which a plurality of closed vesicles and / or particles of a polycondensation polymer having hydroxyl groups are dispersed in water.

[0055] In the mixing step, the particles of the closed vesicles and / or the polycondensation polymer are added to the water while stirring the water with a stirrer, so that the particles of the closed vesicles and / or the polycondensation polymer are mixed with the water. When the temperature of the water is 60°C or higher, the particles of the closed vesicles and / or the polycondensation polymer are easily stirred well.

[0056] When using closed vesicles and polycondensation polymer particles, a mixed solution may be produced by mixing a solution obtained by adding closed vesicles to water with a solution obtained by adding polycondensation polymer particles to water, or a mixed solution may be produced by adding closed vesicles and polycondensation polymer particles to the same water.

[0057] The stirring speed of the water in the mixing step is preferably 1000 rpm or more and 18000 rpm or less. When the stirring speed is 1000 rpm or more, the particles of the closed vesicles and / or polycondensation polymer are sufficiently stirred in the water. Also, when the stirring speed is 18000 rpm or less, the particles of the closed vesicles and / or polycondensation polymer are excessively finely sheared, which can prevent a decrease in the emulsifying ability of the asphalt emulsion.

[0058] In order to maintain the dispersibility of the closed vesicles and / or polycondensation polymer particles, the mixed solution obtained by the mixing step may be continuously stirred at a speed slower than that in the mixing step until the mixed solution is used in the emulsification step.

[0059] In the emulsification process carried out after the mixing process, asphalt is mixed with the mixed solution obtained in the mixing process to obtain an asphalt emulsion containing emulsion particles in which the surface of the asphalt particles is covered with closed vesicles and / or polycondensation polymer particles. The viscosity of the asphalt mixed into the mixed solution at 160°C is 20 mPa·s or more and 1580 mPa·s or less. In asphalt emulsion, multiple emulsion particles are dispersed in water.

[0060] In the emulsification step, asphalt and the mixed solution are mixed to form emulsion particles, and an asphalt emulsion in which the emulsion particles are dispersed is obtained. The asphalt to be mixed with the mixed solution may be in a liquid state heated to above its softening point, or in a solvent state. When heating the asphalt to above its softening point, the temperature of the asphalt is preferably 100°C or higher and 200°C or lower.

[0061] From the viewpoint of improving the emulsifiability of the asphalt emulsion, the agitator for mixing the asphalt and the mixed solution is preferably a homogenizer, a homomixer, or a colloid mill.

[0062] In addition, the method for producing an asphalt emulsion preferably further includes a first addition step of adding a saturated fatty acid to the asphalt before the emulsification step. In the first addition step, the saturated fatty acid is added to the asphalt. Then, in the emulsification step carried out after the first addition step, the asphalt containing the saturated fatty acid is mixed with the mixed solution. By including the first addition step in the method for producing an asphalt emulsion, the tire adhesion rate of the obtained asphalt emulsion can be further reduced.

[0063] In addition, the method for producing an asphalt emulsion preferably further includes a cooling step of cooling the asphalt emulsion after the emulsification step. In the cooling step, the asphalt emulsion is cooled by air cooling or water cooling at a cooling rate faster than the cooling rate during cooling. In the cooling step, the temperature of the asphalt emulsion after cooling is preferably 100°C or less, more preferably 70°C or less, and even more preferably 25°C or less. If the asphalt emulsion after cooling is 100°C or less, aggregation of asphalt particles can be prevented. In addition, the temperature of the asphalt emulsion after cooling is preferably 1°C or more, more preferably 5°C or more, and even more preferably 10°C or more. If the asphalt emulsion after cooling is 1°C or more, separation of the asphalt emulsion can be suppressed.

[0064] In addition, the method for producing an asphalt emulsion preferably further includes a second addition step of adding a pH adjuster to the particles of closed vesicles and / or polycondensation polymer before the mixing step. In the second addition step, the pH adjuster is added to the particles of closed vesicles and / or polycondensation polymer. Then, in the mixing step carried out after the second addition step, the particles of closed vesicles and / or polycondensation polymer containing the pH adjuster are mixed with water. By including the second addition step in the method for producing an asphalt emulsion, cationic asphalt emulsions and anionic asphalt emulsions can be easily prepared.

[0065] Although the embodiments have been described above, the present invention is not limited to the above-described embodiments, and includes all aspects encompassed by the concept of the present invention and the scope of the claims, and can be modified in various ways within the scope of the present invention. EXAMPLES

[0066] Next, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0067] Example 1 First, particles of a polycondensation polymer having a hydroxyl group were mixed with water to obtain a mixed solution shown in Table 1. Then, the mixed solution was mixed with asphalt shown in Table 1 to produce an asphalt emulsion.

[0068] Example 2 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0069] Example 3 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0070] Example 4 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0071] Example 5 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0072] Example 6 First, closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles were mixed with water to obtain a mixed solution shown in Table 1. Next, the mixed solution was mixed with asphalt shown in Table 1 to produce an asphalt emulsion.

[0073] Example 7 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0074] Example 8 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0075] Example 9 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0076] Example 10 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 1 were used.

[0077] Example 11 First, particles of a polycondensation polymer having a hydroxyl group were mixed with water to obtain a mixed solution shown in Table 1. Next, tallow hardened fatty acid (Nippo ST, manufactured by NOF Corporation) was added as a saturated fatty acid to the asphalt shown in Table 1 that had been heated to a softening point or higher. Next, the mixed solution was mixed with the asphalt to which the saturated fatty acid had been added to produce an asphalt emulsion.

[0078] Example 12 Asphalt emulsions were produced in the same manner as in Example 11, except that the asphalts shown in Table 1 were used.

[0079] Comparative Example 1 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 2 were used.

[0080] Comparative Example 2 An asphalt emulsion was produced in the same manner as in Example 1, except that the mixed solution and asphalt shown in Table 2 were used.

[0081] [evaluation] The asphalt emulsions obtained in the above Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2.

[0082] [1] Engler degree The Engler degree of the asphalt emulsion was measured in accordance with JIS K 2208.

[0083] [2] Emulsification The asphalt emulsions immediately after production were visually inspected and ranked as follows: ○: Emulsified. ×: No emulsification.

[0084] [Table 1]

[0085] [Table 2]

[0086] As shown in Table 1, in Examples 1 to 12, the viscosity of the asphalt particles contained in the asphalt emulsion at 160°C was 20 mPa·s or more and 1580 mPa·s or less, suggesting that the asphalt emulsion exhibited good emulsification properties and therefore good workability. On the other hand, as shown in Table 2, in Comparative Examples 1 and 2, the viscosity of the asphalt particles contained in the asphalt emulsion at 160°C was outside the range of 20 mPa·s or more and 1580 mPa·s or less, suggesting that the emulsification properties of the asphalt emulsion were poor and that the workability was also poor.

Claims

1. The emulsion particles are contained in an aqueous phase, The emulsion particles include asphalt particles and particles of closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having a hydroxyl group, The surface of the asphalt particles is covered with the closed vesicles and / or the polycondensation polymer particles, The viscosity of the asphalt particles at 160 ° C. is 20 mPa · s or more and 1580 mPa · s or less, The Engler degree at 25°C is 1 or more and 60 or less. Asphalt emulsion.

2. The asphalt emulsion of claim 1 , wherein the asphalt emulsion further comprises a saturated fatty acid.

3. The asphalt emulsion according to claim 1 or 2, wherein the asphalt particles are soft asphalt particles.

4. The asphalt emulsion according to any one of claims 1 to 3, wherein the content of the emulsion particles in the asphalt emulsion is 1% or more and 80% or less.

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