Method for producing asphalt emulsion and method for adjusting viscosity of asphalt emulsion

Abstract

To provide a method for producing an asphalt emulsion that allows easy viscosity adjustment and maintains good emulsifiability over a long period of time, and to provide a method for adjusting viscosity of asphalt emulsion.SOLUTION: The method for producing asphalt emulsion includes a mixing step of mixing a closed vesicle formed with amphipathic substance that spontaneously forms a closed vesicle and / or a particle of polycondensation polymer having hydroxyl group with water to yield a mixture solution, an emulsification step of mixing an asphalt and the mixture solution to yield an emulsion containing an emulsion particle in which the surface of asphalt particle is covered with the closed vesicle and / or the particle of the polycondensation polymer, and a water addition step of adding water to the emulsion.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing an asphalt emulsion and a method for adjusting the viscosity of an asphalt emulsion.

Background Art

[0002] Conventionally, for asphalt emulsions, asphalt has been emulsified by adding a surfactant to asphalt. For example, Patent Document 1 describes an emulsifier for asphalt composed of a specific cationic surfactant.

[0003] However, depending on the type of asphalt, which is the oil phase, the type of surfactant suitable for emulsifying the asphalt differs. Therefore, in an asphalt emulsion emulsified with a surfactant such as that in Patent Document 1 (hereinafter also referred to as a surfactant-type asphalt emulsion), it is necessary to select a surfactant according to the type of asphalt and the type of emulsion to be produced. Furthermore, in a surfactant-type asphalt emulsion, over time, the emulsifying effect of the surfactant decreases, and the emulsified asphalt may separate from the aqueous phase.

[0004] Also, when water is added to a surfactant-type asphalt emulsion for the purpose of adjusting the viscosity of the asphalt emulsion, the emulsified asphalt may separate from the aqueous phase, and a concentration gradient of asphalt in the asphalt emulsion may occur. Furthermore, the long-term stability of the emulsifiability of the asphalt emulsion decreases. Thus, it is difficult to adjust the viscosity of the asphalt emulsion.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a method for producing an asphalt emulsion and a method for adjusting the viscosity of an asphalt emulsion, which are easy to adjust the viscosity and can maintain good emulsifying properties over a long period of time.

Means for Solving the Problems

[0007] [1] A mixing step of mixing closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensed polymer having a hydroxyl group with water to obtain a mixed solution, and mixing asphalt with the mixed solution to obtain an emulsion containing emulsion particles in which the surface of the asphalt particles is covered with the closed vesicles and / or the particles of the polycondensed polymer; and a water addition step of adding water to the emulsion. A method for producing an asphalt emulsion. [2] The production method of the asphalt emulsion according to [1] above, wherein the content ratio of the asphalt particles contained in the asphalt emulsion is 40% or more and 80% or less. [3] The production method of the asphalt emulsion according to [1] or [2] above, wherein in the water addition step, water is added in an amount of 125% by mass or less based on the total amount of the asphalt contained in the emulsion. [4] The production method of the asphalt emulsion according to any one of [1] to [3] above, further having a first addition step of adding a saturated fatty acid to the asphalt before the emulsification step. [5] The production method of the asphalt emulsion according to any one of [1] to [4] above, further having a cooling step of cooling the asphalt emulsion after the water addition step. [6] The production method of the asphalt emulsion according to any one of [1] to [5] above, wherein the asphalt particles are soft asphalt particles. [7] The production method of the asphalt emulsion according to any one of [1] to [6] above, further having a second addition step of adding a pH adjuster to the closed vesicles and / or the particles of the polycondensed polymer before the mixing step. [8] A method for adjusting the viscosity of an asphalt emulsion, which comprises mixing an asphalt emulsion containing, in an aqueous phase, emulsion particles in which the surface of asphalt particles is covered with closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having a hydroxyl group, and water to lower the viscosity of the asphalt emulsion. [9] The method for adjusting the viscosity of an asphalt emulsion according to [8] above, wherein the content ratio of the asphalt particles contained in the asphalt emulsion after adding water is 40% or more and 80% or less.

[10] The method for adjusting the viscosity of an asphalt emulsion according to [8] or [9] above, wherein the amount of water added to the asphalt emulsion before adding water is 125% by mass or less based on the total amount of the asphalt particles contained in the asphalt emulsion before adding water.

[11] The method for adjusting the viscosity of an asphalt emulsion according to any one of [8] to

[10] above, wherein the asphalt emulsion further contains a saturated fatty acid.

[12] The method for adjusting the viscosity of an asphalt emulsion according to any one of [8] to

[11] above, which comprises cooling the asphalt emulsion after adding water to the asphalt emulsion before adding water.

[13] The method for adjusting the viscosity of an asphalt emulsion according to any one of [8] to

[12] above, wherein the asphalt particles are soft asphalt particles.

[14] The method for adjusting the viscosity of an asphalt emulsion according to any one of [8] to

[13] above, wherein the asphalt emulsion further contains a pH adjuster.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide a method for producing an asphalt emulsion and a method for adjusting the viscosity of an asphalt emulsion, which are easy to adjust the viscosity and can maintain good emulsifying properties over a long period of time.

Embodiments for Carrying Out the Invention

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

[0010] First, a method for producing an asphalt emulsion according to an embodiment will be described.

[0011] The method for producing an asphalt emulsion according to the embodiment includes a mixing step of mixing closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having a hydroxyl group with water to obtain a mixed solution, an emulsifying step of mixing asphalt and the mixed solution to obtain an emulsion containing emulsion particles in which the surface of the asphalt particles is covered with the closed vesicles and / or the particles of the polycondensation polymer, and a water addition step of adding water to the emulsion.

[0012] In the asphalt emulsion obtained by the method for producing an asphalt emulsion according to the embodiment, the emulsified emulsion particles are contained in the aqueous phase. The emulsion particles include asphalt particles that 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 a polycondensation polymer having a hydroxyl group (hereinafter, also simply referred to as particles of the polycondensation polymer). Thus, the asphalt emulsion is an O / W type emulsion in which the emulsion particles are dispersed in the aqueous phase.

[0013] The surface of the asphalt particles is covered with closed vesicles and / or particles of the polycondensation polymer. Whether the surface of the asphalt particles is covered only with closed vesicles, only with particles of the polycondensation polymer, or with both closed vesicles and particles of the polycondensation polymer, the emulsifying property of the emulsion particles is the same. Therefore, the emulsion particles may have only closed vesicles, only particles of the polycondensation polymer, or both closed vesicles and particles of the polycondensation polymer with respect to the closed vesicles and the particles of the polycondensation polymer.

[0014] When the closed vesicles and / or the particles of the polycondensation polymer cover the surface of the asphalt particles, the emulsifying property of the asphalt emulsion is maintained by the following mechanism.

[0015] The closed vesicles formed by the amphiphilic substance that spontaneously forms closed vesicles have the ability to form closed vesicles spontaneously in water. The particles of the closed vesicles and the polycondensed polymer are known as particles having so-called three-phase emulsifying ability. Since the surfaces of the particles of the closed vesicles and the polycondensed polymer are hydrophilic, repulsion occurs between the particles of the closed vesicles and the polycondensed polymer. By arranging the particles of the closed vesicles or the polycondensed polymer on the surface of the asphalt particles, that is, by covering the surface of the asphalt particles with the particles of the closed vesicles or the polycondensed polymer, repulsion occurs between the asphalt particles. Since such repulsion between the asphalt particles is greater than the attractive force generated between the asphalt particles, aggregation of the asphalt particles in the aqueous phase is suppressed, and the dispersibility of the emulsion particles is maintained and improved.

[0016] The three-phase emulsification method enables emulsification by the particles of the closed vesicles or the polycondensed polymer intervening at the interface between the oil phase and the aqueous phase and adhering to the oil phase by the van der Waals force. This three-phase emulsification mechanism is completely different from the emulsification mechanism by a surfactant that maintains the emulsified state by lowering the oil-water interfacial tension with the hydrophilic part and the hydrophobic part facing the aqueous phase and the oil phase, respectively (see, for example, Japanese Patent Publication No. 3855203). In the asphalt emulsion obtained by the method for producing an asphalt emulsion according to the embodiment, as described above, the particles of the closed vesicles or the polycondensed polymer emulsify the asphalt particles.

[0017] The amphiphilic substance is an amphiphilic substance having the ability to form closed vesicles in water, for example, a substance capable of forming a bilayer membrane in water (that is, capable of forming vesicles in water). As the amphiphilic substance that forms closed vesicles, a derivative of polyoxyethylene hydrogenated castor oil represented by the following formula (1), or a halogen salt derivative of a dialkylammonium derivative, trialkylammonium derivative, tetraalkylammonium derivative, dialkenylammonium derivative, trialkenylammonium derivative, or tetraalkenylammonium derivative represented by the following formula (2) is preferable. Among them, polyoxyethylene hydrogenated castor oil is preferable.

[0018]

Chem.

[0019] In formula (1), E (E = L + M + N + X + Y + Z), which is the average number of moles of ethylene oxide added, is preferably 3 or more and 100 or less.

[0020]

Chem.

[0021] In formula (2), R1 and R2 are each independently an alkyl group or alkenyl group having 8 to 22 carbon atoms, R3 and R4 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms, and X is preferably F, Cl, Br, or I.

[0022] Preferable examples of the amphiphilic substance include, in addition to the above, phospholipids and phospholipid derivatives, particularly those in which a hydrophobic group and a hydrophilic group are ester-bonded.

[0023] As the phospholipid, among the structures represented by the following formula (3), DLPC (1,2-Dilauroyl-sn-glycero-3-phospho-rac-1-choline) having a carbon chain length of 12, DMPC (1,2-Dimyristoyl-sn-glycero-3-phospho-rac-1-choline) having a carbon chain length of 14, and DPPC (1,2-Dipalmitoyl-sn-glycero-3-phospho-rac-1-choline) having a carbon chain length of 16 are preferable.

[0024]

Chem.

[0025] 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) with a carbon chain length of 12, the Na salt or NH4 salt of DMPG (1,2-Dimyristoyl-sn-glycero-3-phospho-rac-1-glycerol) with 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) with a carbon chain length of 16 are preferred.

[0026]

Chemical formula

[0027] Furthermore, preferred examples of phospholipids include lecithins such as egg yolk lecithin or soybean lecithin.

[0028] Also, other preferred examples of amphiphilic substances include fatty acid esters. Preferred fatty acid esters include glycerol fatty acid esters, polyglycerol fatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, and propylene glycol fatty acid esters.

[0029] As for polyglycerol fatty acid esters, the fatty acid can be saturated or unsaturated, a straight-chain fatty acid or a branched fatty acid, and it is preferably an ester of the fatty acid and polyglycerol. Among them, 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, and decaglyceryl myristate is even more preferred.

[0030] As the sucrose fatty acid ester, sucrose laurate, sucrose myristate, sucrose palmitate, sucrose stearate, and sucrose oleate are preferable.

[0031] The polycondensed polymer constituting the particles of the polycondensed polymer is preferably a natural polymer or a synthetic polymer, and is appropriately selected according to the use of the asphalt emulsion. Natural polymers are preferable in terms of excellent safety and generally low cost, and sugar polymers are more preferable in terms of excellent emulsifying function.

[0032] The particles of the polycondensed polymer include single particles of the polycondensed polymer and those in which single particles of the polycondensed polymer are connected to each other, but do not include aggregates (having a network structure) of the polycondensed polymer before being made into single particles.

[0033] Saccharide polymers are polymers having a glucoside structure such as cellulose and starch. For example, those produced by microorganisms with several saccharides among monosaccharides such as ribose, xylose, rhamnose, fucose, glucose, mannose, glucuronic acid, gluconic acid as constituent elements, xanthan gum, gum arabic, guar gum, karaya gum, carrageenan, pectin, fucoidan, quince seed gum, tragacanth gum, locust bean gum, galactomannan, curdlan, gellan gum, fucogel, casein, gelatin, starch, collagen, hyaluronic acid, hyaluronic acid derivatives, natural polymers such as jellyfish polysaccharide and their derivatives, semi-synthetic polymers such as methylcellulose, ethylcellulose, cationized cellulose, methylhydroxypropyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, sodium carboxymethyl cellulose, propylene glycol alginate, cellulose crystals, starch-sodium acrylate graft polymer, hydrophobized hydroxypropylmethyl cellulose, synthetic polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, carboxyvinyl polymer, polyacrylate, polyethylene oxide are preferred. Among them, carboxymethyl cellulose, cationized cellulose, hydroxyethyl cellulose are more preferred.

[0034] The total amount of the particles of the closed vesicles and the polycondensed polymer is preferably 0.01% by mass or more, more preferably 0.10% by mass or more, and still more preferably 0.30% by mass or more with respect to the total amount of the asphalt emulsion. Also, the total amount of the particles of the closed vesicles and the polycondensed polymer is preferably 30% by mass or less, more preferably 10% by mass or less, and still more preferably 3% by mass or less with respect to the total amount of the asphalt emulsion. When the total amount of the particles of the closed vesicles and the polycondensed polymer is 0.01% by mass or more with respect to the total amount of the asphalt emulsion, the emulsifying property of the asphalt emulsion is good, and the emulsifying property improves as the total amount of the particles of the closed vesicles and the polycondensed polymer increases. Also, when the total amount of the particles of the closed vesicles and the polycondensed polymer is at a high concentration, it is possible to suppress the adhesion of the asphalt emulsion to the tires of automobiles after the asphalt emulsion is sprayed onto the pavement. That is, the tire adhesion rate of the asphalt emulsion can be reduced. On the other hand, if the total amount of the particles of the closed vesicles and the polycondensed polymer is about 30% by mass with respect to the total amount of the asphalt emulsion, the emulsifying property of the asphalt emulsion is sufficiently good.

[0035] The total amount of the particles of the closed vesicles and the polycondensed polymer is the total amount of the particles of the closed vesicles and the polycondensed polymer that constitute the emulsion particles, and does not include the particles of the closed vesicles and the polycondensed polymer that do not constitute the emulsion particles.

[0036] The average particle diameter of the particles of the closed vesicles and the polycondensed polymer is 8 nm or more and 800 nm or less before forming the emulsion particles, but is 8 nm or more and 500 nm or less in the asphalt emulsion. The average particle diameter of the particles of the closed vesicles and the polycondensed polymer is a value measured by the dynamic light scattering method using a particle size distribution measuring device FPAR (manufactured by Otsuka Electronics Co., Ltd.) and obtained by Contin analysis. Since the method for preparing the particles of the closed vesicles and the polycondensed polymer having an average particle diameter within the above range is conventionally known as a method for preparing particles having a three-phase emulsifying ability, as disclosed in Patent No. 3855203, etc., it is omitted here for convenience.

[0037] In addition, when light scattering measurement is performed on the mixed solution described below used for emulsifying the oily component, if the average particle diameter of the closed vesicles and the particles of the polycondensed polymer 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 the particles of the polycondensed polymer are capable of three-phase emulsification. Further, by performing atomic force microscope (AFM) observation on the emulsion particles contained in the asphalt emulsion and confirming that at least one of the closed vesicles and the particles of the polycondensed polymer adheres to the surface of the asphalt particles, the emulsion particles can be confirmed.

[0038] The content ratio of the emulsion particles contained in the asphalt emulsion is preferably 1% or more, more preferably 25% or more, and still more preferably 40% or more. Also, the content ratio of the emulsion particles contained in the asphalt emulsion is preferably 80% or less, more preferably 75% or less, and still more preferably 70% or less. When the content ratio of the emulsion particles contained in the asphalt emulsion is within the above range, it is possible to produce an asphalt emulsion that sufficiently satisfies the performance as an emulsion for paving, and the workability of the asphalt emulsion can be improved.

[0039] The content ratio of the asphalt particles contained in the asphalt emulsion is preferably 40% or more, more preferably 45% or more, and still more preferably 50% or more. Also, the content ratio of the asphalt particles contained in the asphalt emulsion is preferably 80% or less, more preferably 70% or less, and still more preferably 60% or less. When the content ratio of the asphalt particles contained in the asphalt emulsion is within the above range, it is possible to produce an asphalt emulsion that sufficiently satisfies the performance as an emulsion for paving, and the workability of the asphalt emulsion can be improved.

[0040] The asphalt particles contained in the asphalt emulsion are the asphalt particles constituting the emulsion particles, and do not include asphalt particles that do not constitute the emulsion particles.

[0041] The average particle diameter 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. Also, the average particle diameter 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 diameter of the asphalt particles is within the above range, the emulsifiability of the asphalt emulsion is good. The average particle diameter of the asphalt particles is a value measured by the dynamic light scattering method using a particle size distribution measuring device FPAR (manufactured by Otsuka Electronics Co., Ltd.) and obtained by Contin analysis.

[0042] In the asphalt emulsion, the aqueous phase is a medium for dispersing emulsion particles.

[0043] 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 with respect to the total amount of the asphalt emulsion. Also, 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 with respect to 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.

[0044] Also, the asphalt emulsion preferably further contains a saturated fatty acid. Preferred saturated fatty acids include 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, heneicosylic acid, behenic acid, tricosylic acid, and lignoceric acid. When the asphalt emulsion contains a saturated fatty acid, it is possible to suppress the adhesion of the asphalt emulsion after spraying on the pavement to the tires of automobiles. That is, the tire adhesion rate of the asphalt emulsion 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 with respect to the total amount of the asphalt emulsion. When the total amount of the saturated fatty acids is within the above range, the tire adhesion rate of the asphalt emulsion can be sufficiently reduced.

[0046] As the asphalt constituting the asphalt particles, petroleum asphalt produced from petroleum is preferable. Examples of the petroleum asphalt include soft asphalt and hard asphalt. Further, the asphalt may be decolorized asphalt. The decolorized asphalt contains polymer particles (decolorizing emulsion). The type of the asphalt constituting the asphalt particles is appropriately selected according to the use of the asphalt emulsion.

[0047] In addition, in a conventional tire adhesion-inhibiting type asphalt emulsion (surfactant type asphalt emulsion), mainly hard asphalt is used, and in an asphalt emulsion using soft asphalt, the tire adhesion rate is poor. 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 characteristics such as good emulsifiability, workability, and low tire adhesion rate.

[0048] Further, the asphalt emulsion may further contain a pH adjuster. As the acidic pH adjuster, acetic acid and hydrochloric acid are preferable. As the alkaline pH adjuster, caustic soda (sodium hydroxide) is preferable.

[0049] In the method for producing an asphalt emulsion according to the embodiment, a nonionic asphalt emulsion can be produced. Depending on the use of the asphalt emulsion, various pH adjusters can be contained in the asphalt emulsion, whereby a cationic asphalt emulsion or an anionic asphalt emulsion can be easily prepared. On the other hand, since a cationic type is widely used for conventional asphalt emulsions (surfactant type asphalt emulsions), when an alkaline pH adjuster is added to a conventional asphalt emulsion, the asphalt emulsion deteriorates. Therefore, it is not easy to prepare an anionic asphalt emulsion with a conventional asphalt emulsion.

[0050] Further, the asphalt emulsion may contain optional components to such an extent that the emulsifying property is not reduced. Examples of such optional components include polyhydric alcohols, glycol ethers, surfactants, liquid oils, antiseptic components, and other additives. The asphalt emulsion may contain one kind of optional component or a combination of two or more kinds of optional components. The total amount of the optional components contained in the asphalt emulsion is appropriately set according to the use of the asphalt emulsion.

[0051] Such an asphalt emulsion is suitable for an asphalt emulsion for paving that requires high workability.

[0052] The method for producing an asphalt emulsion for producing such an asphalt emulsion as described above includes a mixing step, an emulsifying step, and a water addition step.

[0053] In the mixing step, a closed vesicle formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensed polymer having a hydroxyl group are mixed with water to obtain a mixed solution. In the mixed solution, a plurality of closed vesicles and / or a plurality of particles of the polycondensed polymer are dispersed in water.

[0054] In the mixing step, the closed vesicles and / or polycondensation polymer particles are added to the water while stirring the water with a stirrer, thereby mixing the closed vesicles and / or polycondensation polymer particles with the water. When the water temperature is 60°C or higher, the closed vesicles and / or polycondensation polymer particles are easily stirred.

[0055] When using closed vesicles and particles of a polycondensation polymer, a mixed solution may be produced by mixing a solution obtained by adding closed vesicles to water with a solution obtained by adding particles of a polycondensation polymer to water, or a mixed solution may be produced by adding closed vesicles and particles of a polycondensation polymer to the same water.

[0056] 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 thoroughly stirred into the water. When the stirring speed is 18000 rpm or less, the particles of the closed vesicles and / or polycondensation polymer are not excessively finely sheared, which can prevent a decrease in the emulsifying ability of the asphalt emulsion.

[0057] 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 it is used in the emulsification step.

[0058] In the emulsification process, which follows the mixing process, asphalt is mixed with the mixed solution obtained in the mixing process to obtain an emulsion containing emulsion particles in which the surfaces of asphalt particles are covered with closed vesicles and / or polycondensation polymer particles. In the emulsion, multiple emulsion particles are dispersed in water.

[0059] In the emulsification process, emulsion particles are formed by mixing asphalt and a mixed solution, and an 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 above the softening point or in a solvent state. When the asphalt is heated above the softening point, the temperature of the asphalt is preferably 100°C or higher and 200°C or lower.

[0060] From the viewpoint of improving the emulsifiability of the asphalt emulsion, the stirrer for mixing the asphalt and the mixed solution is preferably a homogenizer, a homomixer, or a colloid mill.

[0061] In the water addition step performed after the emulsification step, water is added to the emulsion obtained in the emulsification step. Thus, an asphalt emulsion can be obtained. By adding water to the emulsion, the Engler degree, which is the viscosity of the asphalt emulsion, can be easily adjusted. Such an asphalt emulsion can maintain good emulsifiability over a long period.

[0062] If water is added to a surfactant-type asphalt emulsion to adjust its viscosity, the emulsified asphalt may separate from the aqueous phase, resulting in a concentration gradient of the asphalt in the surfactant-type asphalt emulsion. Furthermore, the long-term stability of the emulsifiability of the surfactant-type asphalt emulsion decreases.

[0063] Also, in the water addition step, preferably 125% by mass or less of water, more preferably 90% by mass or less of water, and even more preferably 65% by mass or less of water is added with respect to the total amount of asphalt contained in the emulsion. When 125% by mass or less of water is added with respect to the total amount of asphalt, it is possible to produce an asphalt emulsion that fully satisfies the specifications as a paving emulsion, and the emulsifiability of the asphalt emulsion can be improved.

[0064] Further, the method for producing an asphalt emulsion preferably further includes a first addition step of adding a saturated fatty acid to asphalt before the emulsification step. In the first addition step, a 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 and the mixed solution are mixed. By having 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.

[0065] Further, the method for producing an asphalt emulsion preferably further includes a cooling step of cooling the asphalt emulsion after the water addition step. In the cooling step, the asphalt emulsion is cooled at a cooling rate faster than the cooling rate during natural cooling such as air cooling or water cooling. In the cooling step, the temperature of the cooled asphalt emulsion is preferably 100°C or lower, more preferably 70°C or lower, and still more preferably 25°C or lower. When the cooled asphalt emulsion is 100°C or lower, aggregation of asphalt particles can be prevented. Also, the temperature of the cooled asphalt emulsion is preferably 1°C or higher, more preferably 5°C or higher, and still more preferably 10°C or higher. When the cooled asphalt emulsion is 1°C or higher, separation of the asphalt emulsion can be suppressed.

[0066] Further, the method for producing an asphalt emulsion preferably further includes a second addition step of adding a pH adjuster to the particles of the closed vesicles and / or the polycondensed polymer before the mixing step. In the second addition step, the pH adjuster is added to the particles of the closed vesicles and / or the polycondensed polymer. Then, in the mixing step carried out after the second addition step, the particles of the closed vesicles and / or the polycondensed polymer containing the pH adjuster and water are mixed. By having the second addition step in the method for producing an asphalt emulsion, a cationic asphalt emulsion or an anionic asphalt emulsion can be easily prepared.

[0067] Next, the method for adjusting the viscosity of the asphalt emulsion of the embodiment will be described.

[0068] The method for adjusting the viscosity of the asphalt emulsion according to the embodiment reduces the viscosity of the asphalt emulsion by mixing an asphalt emulsion containing emulsion particles in an aqueous phase, wherein the surface of asphalt particles is covered with closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensed polymer having a hydroxyl group (hereinafter, also simply referred to as the asphalt emulsion before adding water) and water.

[0069] In the method for adjusting the viscosity of the asphalt emulsion according to the embodiment, the viscosity of the asphalt emulsion before and after adding water, that is, the Engler degree of the asphalt emulsion before and after adding water, is adjusted. The asphalt emulsion before adding water in the method for adjusting the viscosity of the asphalt emulsion according to the embodiment corresponds to the emulsion in the method for producing the asphalt emulsion according to the above-described embodiment.

[0070] In the method for adjusting the viscosity of the asphalt emulsion, by mixing the asphalt emulsion before adding water and water, the Engler degree, which is the viscosity of the asphalt emulsion after adding water, can be easily adjusted. The asphalt emulsion after adding water with adjusted viscosity can maintain good emulsifying properties over a long period, similar to the asphalt emulsion before adding water. The asphalt emulsion contains a large number of emulsion particles in the aqueous phase.

[0071] If, in order to adjust the viscosity of a surfactant-type asphalt emulsion, the surfactant-type asphalt emulsion before adding water and water are mixed, the emulsified asphalt may separate from the aqueous phase, resulting in a concentration gradient of asphalt in the surfactant-type asphalt emulsion after adding water. Furthermore, for the surfactant-type asphalt emulsion after adding water, the long-term stability of the emulsifying property decreases.

[0072] The content ratio of asphalt particles contained in the asphalt emulsion after adding water is preferably 40% or more, more preferably 45% or more, and still more preferably 50% or more. Also, the content ratio of asphalt particles contained in the asphalt emulsion after adding water is preferably 80% or less, more preferably 70% or less, and still more preferably 60% or less. When the content ratio of asphalt particles contained in the asphalt emulsion after adding water is within the above range, it is possible to produce an asphalt emulsion that sufficiently satisfies the performance as a paving emulsion, and the workability of the asphalt emulsion can be improved.

[0073] Also, the amount of water added to the asphalt emulsion before adding water is preferably 125% by mass or less, more preferably 90% by mass or less, and still more preferably 65% by mass or less with respect to the total amount of asphalt particles contained in the asphalt emulsion before adding water. When the amount of water added to the asphalt emulsion before adding water is within the above range, it is possible to produce an asphalt emulsion that sufficiently satisfies the specifications as a paving emulsion, and the emulsifiability of the asphalt emulsion can be improved.

[0074] Also, the asphalt emulsion preferably further contains a saturated fatty acid. When a saturated fatty acid is contained, after spraying the asphalt emulsion after adding water onto the pavement, it is possible to suppress the adhesion of the asphalt emulsion to the tires of automobiles. That is, the tire adhesion rate of the asphalt emulsion can be reduced. The saturated fatty acid is preferably added to the asphalt emulsion before adding water, but may also be added to the asphalt emulsion after adding water.

[0075] Further, after adding water to the asphalt emulsion before water addition, it is preferable to cool the asphalt emulsion after water addition. This cooling cools the asphalt emulsion after water addition at a cooling rate faster than the cooling rate during natural cooling, such as by air cooling or water cooling. The temperature of the asphalt emulsion after cooling is preferably 100°C or lower, more preferably 70°C or lower, and even more preferably 25°C or lower. When the asphalt emulsion after cooling is 100°C or lower, aggregation of asphalt particles can be prevented. Further, the temperature of the asphalt emulsion after cooling is preferably 1°C or higher, more preferably 5°C or higher, and even more preferably 10°C or higher. When the asphalt emulsion after cooling is 1°C or higher, separation of the asphalt emulsion can be suppressed.

[0076] Further, the asphalt emulsion may further contain a pH adjuster. Depending on the use of the asphalt emulsion, various pH adjusters can be contained in the asphalt emulsion to easily prepare a cationic asphalt emulsion or an anionic asphalt emulsion. The pH adjuster is preferably added to the asphalt emulsion before water addition, but may also be added to the asphalt emulsion after water addition.

[0077] As described above, the embodiments have been explained, but the present invention is not limited to the above embodiments, includes all aspects included in the concept and claims of the present invention, and can be variously modified within the scope of the present invention.

Examples

[0078] Next, examples and comparative examples will be described, but the present invention is not limited to these examples.

[0079] (Example 1) First, particles of a polycondensed polymer having a hydroxyl group and water were mixed to obtain a mixed solution shown in Table 1. Subsequently, the mixed solution and the asphalt shown in Table 1 were mixed to obtain an emulsion. Subsequently, water was added to the emulsion to produce an asphalt emulsion with adjusted viscosity.

[0080] (Example 2) An asphalt emulsion was produced in the same manner as in Example 1, except that hardened beef tallow fatty acid (manufactured by NOF Corporation: Nippo ST) was added as the saturated fatty acid shown in Table 1.

[0081] (Example 3) An asphalt emulsion was produced in the same manner as in Example 1, except that a cooling process was performed on the asphalt emulsion.

[0082] (Example 4) An asphalt emulsion was produced in the same manner as in Example 1, except that acetic acid was added as the pH adjuster shown in Table 1.

[0083] (Example 5) An asphalt emulsion was produced in the same manner as in Example 1, except that hardened beef tallow fatty acid (manufactured by NOF Corporation: Nippo ST) was added as the saturated fatty acid shown in Table 1 and acetic acid was added as the pH adjuster.

[0084] (Example 6) An asphalt emulsion was produced in the same manner as in Example 1, except that acetic acid was added as the pH adjuster shown in Table 1 and a cooling process was performed.

[0085] (Example 7) An asphalt emulsion was produced in the same manner as in Example 1, except that hardened beef tallow fatty acid (manufactured by NOF Corporation: Nippo ST) was added as the saturated fatty acid shown in Table 1 and a cooling process was performed.

[0086] (Example 8) First, a closed vesicle formed by an amphiphilic substance that spontaneously forms a closed vesicle was mixed with water to obtain a mixed solution shown in Table 1. Subsequently, asphalt to which hardened beef tallow fatty acid (manufactured by NOF Corporation: Nippo ST) was added as the saturated fatty acid was mixed with the mixed solution to obtain an emulsion. Subsequently, water was added to the emulsion to produce an asphalt emulsion with adjusted viscosity.

[0087] (Example 9) An asphalt emulsion was produced in the same manner as in Example 1 except that the mixed solution shown in Table 1 was used.

[0088] (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.

[0089] (Comparative Example 1) First, hardened tallow alkyltrimethylenediamine (manufactured by NOF Corporation: Nippo 10) as a surfactant and water were mixed to obtain the mixed solution shown in Table 2. Subsequently, the mixed solution and the asphalt shown in Table 2 were mixed, and then water was added to produce an asphalt emulsion. Comparative Example 1 is a surfactant-type asphalt emulsion.

[0090] (Comparative Example 2) First, particles of a polycondensed polymer having a hydroxyl group and water were mixed to obtain the mixed solution shown in Table 2. Subsequently, the mixed solution and the asphalt shown in Table 2 were mixed to produce an asphalt emulsion. That is, in Comparative Example 2, the water addition step of adding water to the asphalt emulsion was not performed.

[0091] (Comparative Example 3) An asphalt emulsion was produced in the same manner as in Comparative Example 2 except that the mixed solution and asphalt shown in Table 2 were used.

[0092] [Evaluation] The following evaluations were performed on the asphalt emulsions obtained in the above Examples and Comparative Examples. The results are shown in Tables 1 to 2.

[0093] [1] Emulsification The asphalt emulsions 24 hours after production (in Examples 1 to 10 and Comparative Example 1, the asphalt emulsions after water addition, and in Comparative Examples 2 to 3, the asphalt emulsions without water addition) were visually observed and ranked as follows. ○: The emulsification stability was good. ×: The emulsification stability was poor.

[0094] [2] Storage stability test For the purpose of observing the long-term stability of the emulsifiability of the asphalt emulsion, in accordance with JEAAS 2011 and JIS K 2208, the storage stability tests of the asphalt emulsions obtained in Example 1 and Comparative Example 1 were measured.

[0095] [3] Engler degree In accordance with JIS K 2208, the Engler degrees of the asphalt emulsion before and after adding water were measured. In Comparative Example 1, since the evaluation of the above [1] emulsification was ×, the Engler degree was not measured.

[0096]

Table 1

[0097]

Table 2

[0098] As shown in Table 1, in Examples 1 to 10, since water was added to the emulsion, the Engler degree, which is the viscosity of the asphalt emulsion after adding water, could be adjusted. Thus, the viscosity of the asphalt emulsion could be easily adjusted. Furthermore, the asphalt emulsion with adjusted viscosity could maintain good emulsifiability over a long period. On the other hand, in Comparative Example 1, since water was added to the conventional surfactant-type asphalt emulsion, separation occurred 24 hours after adding water, and furthermore, the viscosity of the asphalt emulsion could not be adjusted. Also, in Comparative Examples 2 to 3, since water was not added, the viscosity of the asphalt emulsion could not be adjusted.

Claims

1. A mixing step of mixing a closed vesicle formed of an amphiphilic substance that spontaneously forms a closed vesicle and / or particles of a polycondensation polymer having a hydroxyl group with water to obtain a mixed solution; An emulsifying step of mixing asphalt with the mixed solution to obtain an emulsion containing emulsion particles in which the surface of the asphalt particles is covered with the closed vesicles and / or the particles of the polycondensation polymer; A water addition step of adding water to the emulsion; A method for producing an asphalt emulsion, comprising: Even when the final water content contained in the asphalt emulsion is fixed, by appropriately changing the ratio between the initial water content at the start of production and the final water addition amount at the end of the process, the Engler degree of the asphalt emulsion is made to have a difference. A method for producing an asphalt emulsion, characterized in that.

2. The content ratio of the asphalt particles contained in the asphalt emulsion is 40% or more and 80% or less. The method for producing an asphalt emulsion according to Claim 1.

3. In the water addition step, water is added in an amount of 125% by mass or less based on the total amount of the asphalt contained in the emulsion. The method for producing an asphalt emulsion according to Claim 1 or 2.

4. After the water addition step, the method for producing an asphalt emulsion according to any one of Claims 1 to 3, further comprising a cooling step of cooling the asphalt emulsion.

5. The asphalt particles are soft asphalt particles. The method for producing an asphalt emulsion according to any one of Claims 1 to 4.

6. An asphalt emulsion viscosity adjustment method, wherein an asphalt emulsion containing emulsion particles in which the surface of asphalt particles is covered with closed vesicles formed of an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having a hydroxyl group in an aqueous phase is mixed with water to produce an asphalt emulsion, and the Engler degree of the asphalt emulsion is lowered compared to the asphalt emulsion before water addition. Even when the final water content contained in the asphalt emulsion is fixed, by appropriately changing the ratio between the initial water content at the start of adjustment and the final water addition amount at the end of the process, the Engler degree of the asphalt emulsion is made to have a difference. A method for adjusting the viscosity of an asphalt emulsion, characterized in that.

7. ​ The content ratio of the asphalt particles contained in the asphalt emulsion after adding water is 40% or more and 80% or less. The method for adjusting the viscosity of the asphalt emulsion according to claim 6.

8. The amount of water added to the asphalt emulsion before adding water is 125% by mass or less based on the total amount of the asphalt particles contained in the asphalt emulsion before adding water. The method for adjusting the viscosity of the asphalt emulsion according to claim 6 or 7.

9. After adding water to the asphalt emulsion before adding water, cooling the asphalt emulsion. The method for adjusting the viscosity of the asphalt emulsion according to any one of claims 6 to 8.

10. The asphalt particles are soft asphalt particles. The method for adjusting the viscosity of the asphalt emulsion according to any one of claims 6 to 9.

11. A mixing step of mixing a closed vesicle formed by an amphiphilic substance that spontaneously forms a closed vesicle and / or particles of a polycondensed polymer having a hydroxyl group with water to obtain a mixed solution, An emulsifying step of mixing asphalt with the mixed solution to obtain an emulsion containing emulsion particles in which the surface of the asphalt particles is covered with the closed vesicles and / or the particles of the polycondensed polymer, A water addition step of adding water to the emulsion, A first addition step of adding a saturated fatty acid to the asphalt before the emulsifying step The manufacturing method of the asphalt emulsion which has.

12. A mixing step of mixing a closed vesicle formed by an amphiphilic substance that spontaneously forms a closed vesicle and / or particles of a polycondensed polymer having a hydroxyl group with water to obtain a mixed solution, An emulsifying step of mixing asphalt with the mixed solution to obtain an emulsion containing emulsion particles in which the surface of the asphalt particles is covered with the closed vesicles and / or the particles of the polycondensed polymer, A water addition step of adding water to the emulsion, A second addition step of adding a pH adjuster to the closed vesicles and / or the particles of the polycondensed polymer before the mixing step The manufacturing method of the asphalt emulsion which has.

13. A method for adjusting the viscosity of an asphalt emulsion, comprising mixing an asphalt emulsion containing emulsion particles in an aqueous phase, wherein the surface of the asphalt particles is covered with closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having a hydroxyl group, and water, to lower the viscosity of the asphalt emulsion, and the asphalt emulsion further contains a saturated fatty acid.

14. A method for adjusting the viscosity of an asphalt emulsion, comprising mixing an asphalt emulsion containing emulsion particles in an aqueous phase, wherein the surface of the asphalt particles is covered with closed vesicles formed by an amphiphilic substance that spontaneously forms closed vesicles and / or particles of a polycondensation polymer having a hydroxyl group, and water, to lower the viscosity of the asphalt emulsion, and the asphalt emulsion further contains a pH adjuster.

Images