Method for manufacturing asphalt emulsion

Abstract

To provide a method for producing an asphalt emulsion having excellent weather resistance, an asphalt emulsion, an asphalt mixture for paving, and a method for road paving.SOLUTION: The present invention pertains to: [1] a method for producing an asphalt emulsion, the method comprising (step 1) a step for melt-mixing asphalt and polyester to obtain an asphalt mixture, and (step 2) a step for adding by mixing an aqueous medium and a surfactant to the asphalt mixture obtained in step 1; [2] an asphalt emulsion containing composite particles, wherein the composite particles contain asphalt and polyester and have the volume median particle diameter (D50) of 1-40 μm; [3] an asphalt mixture for paving, the mixture containing the asphalt emulsion of [2] and an aggregate; and [4] a method for road paving, the method comprising a step for laying the asphalt mixture for paving of [3] onto a road at 150°C or lower.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing asphalt emulsion, asphalt emulsion, asphalt mixture for paving, and road paving method. [Background technology]

[0002] Asphalt paving is used for roads, parking lots, freight yards, and sidewalks because it is relatively easy to lay and the time from the start of paving work to the start of traffic is short. Asphalt paving requires performance such as durability, so it has been proposed to improve the performance of asphalt paving by modifying the asphalt with polyester.

[0003] Furthermore, asphalt has high viscosity at room temperature, resulting in poor workability. Therefore, to ensure the desired workability at room temperature without requiring heating, asphalt emulsion is used, in which asphalt is dispersed in water to reduce its apparent viscosity. Patent Document 1 discloses an additive for asphalt emulsion and an asphalt composition that exhibits strength equivalent to or greater than that of heated asphalt, further improves water resistance, and allows control over the rate of strength development. These include an additive for asphalt emulsion containing a specific binder and a specific hardening agent composition, and an asphalt composition containing the additive for asphalt emulsion and an asphalt emulsion.

[0004] Furthermore, various asphalt-free compositions that can be paved at room temperature have been proposed. Patent Document 2 discloses a road pavement composition that has sufficient strength, develops strength quickly, and enables efficient formation or repair of the pavement, comprising an aqueous dispersion of a resin (A) of a specific acid value neutralized with a basic compound, and a silane coupling agent of a specific structure, which constitutes a binder for aggregates in road pavements or the surface layer of the pavement. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 09-59354 [Patent Document 2] Japanese Patent Publication No. 2005-126998 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Asphalt pavement has a problem: prolonged exposure to sunlight causes deterioration due to ultraviolet rays, leading to cracking. This problem is particularly serious in areas with strong sunlight intensity. When asphalt pavement deteriorates, repairs become necessary. Repairing the pavement increases maintenance costs and significantly impacts automobile traffic. Therefore, there is a demand for asphalt pavement that is less susceptible to deterioration from ultraviolet rays and has excellent weather resistance. In particular, from the standpoint of energy conservation and ease of construction, there is a demand for asphalt pavement that can be constructed using cold paving with excellent weather resistance. However, cold pavement tends to have a high moisture content, and deterioration due to ultraviolet rays is more pronounced.

[0007] The technology described in Patent Document 1 results in insufficient weather resistance for asphalt pavement. Patent Document 2 does not specifically disclose any compositions containing asphalt, and is not intended to improve the weather resistance of asphalt pavement. The present invention relates to a method for producing asphalt emulsion, asphalt emulsion, asphalt mixture for paving, and road paving method. [Means for solving the problem]

[0008] The inventor has found that an asphalt emulsion with suppressed deterioration by ultraviolet rays and improved weather resistance can be produced by a method for producing an asphalt emulsion including Step 1: melting and mixing asphalt and polyester to obtain an asphalt mixture, and Step 2: adding and mixing an aqueous medium and a surfactant to the asphalt mixture obtained in Step 1. That is, the present invention provides the following [1] to [4]. [1] A method for producing an asphalt emulsion including the following Step 1 and Step 2. Step 1: A step of melting and mixing asphalt and polyester to obtain an asphalt mixture Step 2: A step of adding and mixing an aqueous medium and a surfactant to the asphalt mixture obtained in Step 1 [2] An asphalt emulsion containing composite particles, where the composite particles contain asphalt and polyester and have a volume median particle diameter (D , ) of 1 μm or more and 40 μm or less, the asphalt emulsion. [3] An asphalt binder for paving containing the asphalt emulsion of [2] above and an aggregate [4] A road paving method including a step of constructing the asphalt binder for paving of [3] above on a road at 150° C. or lower. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a method for producing an asphalt emulsion excellent in weather resistance, an asphalt emulsion, an asphalt binder for paving, and a road paving method. [Embodiments for Carrying Out the Invention]

[0010] [Method for Producing Asphalt Emulsion] The method for producing an asphalt emulsion of the present invention includes the following Step 1 and Step 2. Step 1: A step of melting and mixing asphalt and polyester to obtain an asphalt mixture Step 2: A step of adding and mixing an aqueous medium and a surfactant to the asphalt mixture obtained in Step 1

[0011] The present invention also includes the following embodiments: A method for producing an asphalt emulsion, comprising the following steps 1 and 2. Step 1: A process to obtain an asphalt mixture by melt-mixing asphalt and polyester having a weight-average molecular weight of 2,000 or more and 100,000 or less. Step 2: Adding and mixing an aqueous medium and a surfactant to the asphalt mixture obtained in Step 1.

[0012] Although the reason for the effects obtained by the present invention is not clear, it has been found that the asphalt emulsion obtained by the manufacturing method of the present invention, and the asphalt road surface produced with said asphalt emulsion, have improved weather resistance.

[0013] [Process 1] In step 1, asphalt and polyester are melt-mixed to obtain an asphalt mixture, from the viewpoint of emulsification and weather resistance.

[0014] <Asphalt> Various types of asphalt can be used in this invention. Examples include straight asphalt, which is petroleum asphalt for paving, and modified asphalt. Straight asphalt refers to the residual bituminous substance obtained by subjecting crude oil to atmospheric distillation, vacuum distillation, and other similar processes. Modified asphalts include blown asphalt, asphalt modified with polymer materials such as thermoplastic elastomers and thermoplastic resins, and others. Examples of thermoplastic elastomers include styrene / butadiene / block copolymer (SBS), styrene / isoprene / block copolymer (SIS), and ethylene / vinyl acetate copolymer (EVA). Examples of thermoplastic resins include ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, polyethylene, and polypropylene. Among these, straight asphalt is preferred. The penetration degree of asphalt, particularly straight asphalt, is preferably 40 or higher, more preferably 60 or higher, and even more preferably 80 or higher, from the viewpoint of emulsification properties, and from the viewpoint of pavement strength after construction, it is preferably 250 or lower, more preferably 230 or lower, and even more preferably 210 or lower. Penetration is an indicator of asphalt hardness. The method for measuring penetration is as specified in JIS K2207:2006. Under the test conditions described in JIS K2207:2006, at 25°C, a length of 0.1 mm when a specified needle penetrates perpendicularly into the sample is expressed as 1.

[0015] <Polyester> Polyester contains structural units derived from alcohol components and structural units derived from carboxylic acid components, and is obtained by polycondensation reaction between the carboxylic acid component and the alcohol component. The physical properties of the alcohol component, carboxylic acid component, and polyester will be described below. Polyester can be used alone or in combination of two or more types. In this specification, in polyester, "constituent unit derived from alcohol component" means the structure obtained by removing a hydrogen atom from the hydroxyl group of the alcohol component, and "constituent unit derived from carboxylic acid component" means the structure obtained by removing a hydroxyl group from the carboxyl group of the carboxylic acid component. The term "carboxylic acid component" is a concept that includes not only the carboxylic acid itself, but also the anhydride that decomposes during the reaction to produce acid, and alkyl esters of carboxylic acids (for example, alkyl groups with 1 to 3 carbon atoms). When the carboxylic acid component is an alkyl ester of a carboxylic acid, the number of carbon atoms in the alkyl group, which is the alcohol residue of the ester, is not included in the number of carbon atoms of the carboxylic acid component.

[0016] (Alcohol content) Examples of alcohol components include aliphatic diols, aromatic diols, and polyhydric alcohols with a hydride of three or more. These alcohol components can be used individually or in combination of two or more. From the viewpoint of emulsification, the number of carbon atoms in the aliphatic diol is preferably 4 or more, more preferably 5 or more, and even more preferably 6 or more, and from the viewpoint of weather resistance, it is preferably 16 or less, more preferably 12 or less, and even more preferably 8 or less. Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol. Preferably, one or more are selected from 1,4-butanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, and 1,12-dodecanediol, and more preferably, one or more are selected from 1,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol. Furthermore, from the viewpoint of emulsification, the aliphatic diol is preferably an aliphatic diol having a hydroxyl group at the end of the carbon chain, more preferably an α,ω-aliphatic diol, and even more preferably an α,ω-linear alkanediol. Examples of aromatic diols include bisphenol A and alkylene oxide adducts of bisphenol A. Examples of alkylene oxide adducts of bisphenol A include propylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane and ethylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane. Among these, a combination of propylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane and ethylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane is preferred. Examples of polyhydric alcohols with a valency of 3 or higher include glycerin.

[0017] From the viewpoint of weather resistance, the alcohol component preferably contains an aliphatic diol. The alcohol component may also contain alcohols other than aliphatic diols, but the aliphatic diol content is preferably 70 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and 100 mol% or less of the alcohol component. One preferred embodiment of the present invention is that the alcohol component consists substantially of aliphatic diols.

[0018] The alcohol component may contain a monohydric aliphatic alcohol. From the viewpoint of emulsification, the carbon number of the monohydric aliphatic alcohol is preferably 12 or more, more preferably 14 or more. From the viewpoint of weather resistance, it is preferably 20 or less, more preferably 18 or less. Examples of monohydric aliphatic alcohols include lauryl alcohol, myristyl alcohol, palmityl alcohol, and stearyl alcohol, which have 12 to 20 carbon atoms. The content of monohydric aliphatic alcohol is preferably 20 mol% or less, and more preferably 15 mol% or less, of the total amount of alcohol and carboxylic acid components, from the viewpoint of weather resistance.

[0019] (Carboxylic acid component) Examples of carboxylic acid components include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and polycarboxylic acids with a valency of 3 to 6. These carboxylic acid components can be used individually or in combination of two or more. From the viewpoint of emulsification, the number of carbon atoms in the aliphatic dicarboxylic acid is preferably 4 or more, more preferably 6 or more, and even more preferably 8 or more, and from the viewpoint of weather resistance, it is preferably 14 or less, more preferably 13 or less, and even more preferably 12 or less. The linear hydrocarbon group in aliphatic dicarboxylic acids may be either a straight chain or a branched chain. Examples of aliphatic dicarboxylic acids include succinic acid, suberic acid, azelaic acid, sebacic acid, dodecane di acid, tetradecane di acid, and succinic acid having an alkyl or alkenyl group in its side chain, with a total of 4 to 14 carbon atoms. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid. Examples of polycarboxylic acids with a valency of 3 or higher include trimellitic acid and pyromellitic acid.

[0020] From the viewpoint of weather resistance, the carboxylic acid component preferably contains an aliphatic dicarboxylic acid. The carboxylic acid component may also contain carboxylic acids other than aliphatic dicarboxylic acids. The content of aliphatic dicarboxylic acids is preferably 70 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more of the carboxylic acid component. One preferred embodiment of the present invention is that the carboxylic acid component consists substantially of only aliphatic dicarboxylic acids.

[0021] The carboxylic acid component may contain a monovalent aliphatic carboxylic acid. From the viewpoint of emulsification, the number of carbon atoms in the monovalent aliphatic carboxylic acid is preferably 12 or more, more preferably 14 or more. From the viewpoint of weather resistance, it is preferably 20 or less, more preferably 18 or less. Examples of monovalent aliphatic carboxylic acids include lauric acid, myristic acid, palmitic acid, stearic acid, and alkyl (1 to 3 carbon atoms) esters of these acids, which have 12 to 20 carbon atoms. The content of monovalent aliphatic carboxylic acid is preferably 20 mol% or less, and more preferably 15 mol% or less, of the total amount of alcohol and carboxylic acid components, from the viewpoint of weather resistance.

[0022] (Preferred embodiment of polyester) A preferred embodiment of the polyester comprises a constituent unit derived from an alcohol component containing preferably 70 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more of an α,ω-aliphatic diol having 4 to 16 carbon atoms. It contains a carboxylic acid-derived structural unit that preferably contains 70 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more, an aliphatic dicarboxylic acid having 4 to 14 carbon atoms.

[0023] (Composite resin) The polyester may be a composite resin containing polyester segments and addition polymerization resin segments. Preferably, the composite resin has constituent units derived from both reactive monomers that are covalently bonded to the polyester segments and the addition polymerization resin segments. The polyester segment is made of the aforementioned polyester. Examples of addition polymerization resin segments include addition polymers of raw material monomers containing styrene compounds. "Constituent units derived from both reactive monomers" refers to units formed by the reaction of the functional groups and addition polymerizable groups of both reactive monomers. Examples of addition polymerizable groups include carbon-carbon unsaturated bonds.

[0024] Examples of styrene compounds include unsubstituted or substituted styrenes. Substituents that can be substituted for styrene include alkyl groups having 1 to 5 carbon atoms, halogen atoms, alkoxy groups having 1 to 5 carbon atoms, sulfonic acid groups, or salts thereof. Examples of styrene-based compounds include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrene sulfonic acid, or salts thereof. Among these, styrene is preferred.

[0025] The raw material monomers for addition polymers may include raw material monomers other than styrene compounds. Examples of raw material monomers other than styrene compounds include (meth)acrylic acid esters such as alkyl (meth)acrylate, benzyl (meth)acrylate, and dimethylaminoethyl (meth)acrylate; olefins such as ethylene, propylene, and butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone. Among these, (meth)acrylic acid esters are preferred, and alkyl (meth)acrylates are preferred. The number of carbon atoms in the alkyl group of (meth)acrylate is preferably 1 or more, more preferably 6 or more, even more preferably 8 or more, and preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, iso(or tertiary)butyl (meth)acrylate, isoamyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, isododecyl (meth)acrylate, isopalmityl (meth)acrylate, isostearyl (meth)acrylate, and isobehenyl (meth)acrylate, with 2-ethylhexyl (meth)acrylate being preferred. Note that "(meth)acrylic acid" refers to acrylic acid or methacrylic acid. "(iso or tertiary)" and "(iso)" refer to both cases where these prefixes are present and where they are not, and when these prefixes are absent, it refers to the normal form.

[0026] Examples of both reactive monomers include addition polymerizable monomers having at least one functional group selected from hydroxyl groups, carboxyl groups, epoxy groups, primary amino groups, and secondary amino groups within the molecule. Among these, from the viewpoint of reactivity, addition polymerizable monomers having at least one functional group selected from hydroxyl groups and carboxyl groups are preferred, and addition polymerizable monomers having carboxyl groups are more preferred. Examples of addition polymerizable monomers having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, and maleic acid. Among these, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred, from the viewpoint of reactivity in both polycondensation and addition polymerization reactions.

[0027] The polyester segment content in the composite resin is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less. The content of addition polymerization resin segments in the composite resin is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 60% by mass or less, more preferably 50% by mass or less, and even more preferably 40% by mass or less. The content of constituent units derived from both reactive monomers is preferably 1 mol% or more, more preferably 1.5 mol% or more, even more preferably 2 mol% or more, and preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, based on 100 mol% of the alcohol component of the polyester segment of the composite resin. The total content of polyester segments, addition polymerization resin segments, and constituent units derived from both reactive monomers in the composite resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

[0028] The content of styrene compounds in the raw material monomers of the addition polymerization resin segment is preferably 50% by mass or more, more preferably 65% ​​by mass or more, even more preferably 75% by mass or more, and 100% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. The content of (meth)acrylic acid ester in the raw material monomer of the addition polymerization resin segment is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 35% by mass or less, and even more preferably 25% by mass or less.

[0029] The total content of styrene compounds and (meth)acrylic acid esters in the raw material monomers of the addition polymerization resin segment is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass.

[0030] (Molar ratio of constituent units derived from carboxylic acid component to constituent units derived from alcohol component) The molar ratio of constituent units derived from the carboxylic acid component to constituent units derived from the alcohol component [carboxylic acid component / alcohol component] is preferably 0.6 or higher, more preferably 0.7 or higher, even more preferably 0.8 or higher, and preferably 1.5 or lower, more preferably 1.3 or lower, and even more preferably 1.0 or lower, from the viewpoint of weather resistance.

[0031] (Physical properties of polyester) The weight-average molecular weight of the polyester is preferably 2,000 or more, more preferably 3,000 or more, even more preferably 4,000 or more, even more preferably 5,000 or more, and even more preferably 8,000 or more from the viewpoint of weather resistance, and preferably 100,000 or less, more preferably 80,000 or less, even more preferably 50,000 or less, and even more preferably 35,000 or less from the viewpoint of emulsification. From the viewpoint of weather resistance, the acid value of the polyester is preferably 0.5 mg KOH / g or more, more preferably 1.0 m KOH / g or more, even more preferably 1.5 mg KOH / g or more, and preferably 50 mg KOH / g or less, more preferably 30 mg KOH / g or less, and even more preferably 15 mg KOH / g or less. From the viewpoint of improving weather resistance through reactivity with marten components, the hydroxyl value of the polyester is preferably 2 mg KOH / g or more, more preferably 10 mg KOH / g or more, and even more preferably 20 mg KOH / g or more. From the viewpoint of emulsification, it is preferably 70 mg KOH / g or less, more preferably 50 mg KOH / g or less, and even more preferably 40 mg KOH / g or less. From the viewpoint of weather resistance, the softening point of polyester is preferably 40°C or higher, more preferably 50°C or higher, and even more preferably 60°C or higher. From the viewpoint of emulsification, it is preferably 130°C or lower, more preferably 110°C or lower, and even more preferably 90°C or lower. If the polyester has a glass transition temperature, from the viewpoint of weather resistance, it is preferably 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher, and from the viewpoint of emulsification, it is preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower. When polyester has an endothermic peak temperature, it is preferably 50°C or higher, preferably 60°C or higher, from the viewpoint of weather resistance, and 150°C or lower from the viewpoint of emulsification. The weight-average molecular weight, acid value, hydroxyl value, softening point, and glass transition point of polyester can be measured by the method described in the examples. Note that the weight-average molecular weight, acid value, hydroxyl value, softening point, and glass transition point can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0032] The solubility parameter (SP value) of polyester is preferably 8 or higher, and more preferably 8.5 (cal / cm³), from the viewpoint of weather resistance. 3 ) 1 / 2 More preferably 9 (cal / cm²) 3 ) 1 / 2or less, and from the viewpoint of emulsifying properties, preferably 12 (cal / cm 3 ) 1 / 2 or less, more preferably 11 (cal / cm 3 ) 1 / 2 or less, still more preferably 10 (cal / cm 3 ) 1 / 2 or less. In this specification, the SP value is calculated using the method described in "Specific Interactions and the Miscibility of Polymer Blends" (1991), Technomic Publishing Co. Inc. by Michael M. Coleman, John F. Graf, Paul C. Painter (Pennsylvania State Univ.).

[0033] (Method for producing polyester) The method for producing the polyester is not particularly limited, and for example, it can be produced by polycondensing the above-described alcohol component and carboxylic acid component. The blending amount of each of the alcohol component and the carboxylic acid is such that the molar ratio [carboxylic acid component / alcohol component] of the structural unit derived from the carboxylic acid component to the structural unit derived from the alcohol component is within the above-described numerical range. From the viewpoint of reactivity, the temperature of the polycondensation reaction is preferably 160°C or higher, more preferably 180°C or higher, still more preferably 190°C or higher, and preferably 260°C or lower, more preferably 250°C or lower, still more preferably 240°C or lower. From the viewpoint of reaction rate, an esterification catalyst can be used in the polycondensation reaction. Examples of esterification catalysts include tin(II) compounds that do not have a Sn-C bond, such as di(2-ethylhexanoic acid)tin(II). From the viewpoint of reaction rate, the amount of esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1.0 part by mass or less, and even more preferably 0.6 parts by mass or less, per 100 parts by mass of the total amount of alcohol and carboxylic acid components. In addition to the esterification catalyst, a co-catalyst can be used in the polycondensation reaction. Examples of co-catalysts include pyrogallol compounds such as gallic acid. The amount of co-catalyst used is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, and preferably 0.15 parts by mass or less, more preferably 0.10 parts by mass or less, and even more preferably 0.05 parts by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0034] When polyester is a composite resin, it can be produced, for example, by a method comprising step A, which involves polycondensation of the alcohol component and the carboxylic acid component of the polyester segment, and step B, which involves addition polymerization of the raw material monomers and both reactive monomers of the addition polymerization resin segment. Process A may be performed after process B, or process B may be performed after process A, or process A and process B may be performed simultaneously.

[0035] The addition polymerization temperature in step B is preferably 110°C or higher, more preferably 130°C or higher, and preferably 230°C or lower, more preferably 220°C or lower, and even more preferably 210°C or lower. Radical polymerization initiators can be used in addition polymerization. Examples of radical polymerization initiators include peroxides such as dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). The amount of radical polymerization initiator used is preferably 1 to 20 parts by mass per 100 parts by mass of raw material monomers of the addition polymerization resin segment.

[0036] From the viewpoint of weather resistance, the amount of polyester used in step 1 is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of asphalt.

[0037] The time for melting and mixing in step 1 is preferably 5 minutes or more, more preferably 10 minutes or more, even more preferably 20 minutes or more, and even more preferably 30 minutes or more, from the viewpoint of weather resistance, and preferably 5 hours or less, more preferably 4 hours or less, even more preferably 3 hours or less, and even more preferably 2 hours or less, from the viewpoint of emulsification. From the viewpoint of weather resistance, the temperature during melting and mixing is preferably 130°C or higher, more preferably 140°C or higher, and even more preferably 150°C or higher. From the viewpoint of emulsification, it is preferably 220°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower.

[0038] The stirring device used for melting and mixing is not particularly limited, and general anchor-type stirring blades or propeller-type stirring blades can be used. The stirring speed is preferably 50 rpm or more, more preferably 100 rpm or more, even more preferably 150 rpm or more, and preferably 500 rpm or less, more preferably 450 rpm or less, and even more preferably 400 rpm or less. In addition, from the viewpoint of emulsification, high-speed shearing equipment such as homomixers may be used. The stirring speed of the high-speed shearing equipment is preferably 3,000 rpm or more, more preferably 4,000 rpm or more, even more preferably 5,000 rpm or more, and preferably 15,000 rpm or less, more preferably 12,000 rpm or less, and even more preferably 10,000 rpm or less.

[0039] Thus, an asphalt mixture is obtained. In the resulting asphalt mixture, polyester is dispersed in the asphalt. From the viewpoint of weather resistance, the average dispersion diameter of polyester in the asphalt is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, and preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. The average dispersion diameter of polyester in asphalt can be measured by the method described in the examples below.

[0040] [Process 2] In step 2, an aqueous medium and a surfactant are added to and mixed with the asphalt mixture obtained in step 1.

[0041] (aqueous medium) The aqueous medium is a dispersion medium in which water accounts for the largest proportion by mass. From the viewpoint of weather resistance, the water content in the aqueous medium is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and 100% by mass or less. Other components besides water include alkyl alcohols with 1 to 5 carbon atoms, such as methanol and ethanol; dialkyl ketones with 3 to 5 carbon atoms, such as acetone and methyl ethyl ketone; and organic solvents that dissolve in water, such as cyclic ethers like tetrahydrofuran. One preferred embodiment of the present invention is that the aqueous medium consists substantially of water alone. The solid content of the resulting asphalt emulsion is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, from the viewpoint of weather resistance, and preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less, from the viewpoint of emulsification. It is preferable to add an amount of aqueous medium such that the solid content of the asphalt emulsion falls within the above range.

[0042] (Surfactants) Examples of surfactants include cationic surfactants, anionic surfactants, amphoteric surfactants, and nonionic surfactants, with cationic surfactants being preferred from the viewpoint of emulsification. Examples of cationic surfactants include mineral salts or lower carboxylates, quaternary ammonium salts, etc., of amines such as alkylamines, alkyl polyamines, amidoamines, and alkylimidazolines. Cationic surfactants can also be formulated with other substances, such as water, lower alcohols, solvents like glycols and polyoxyethylene glycol, sugars like glucose and sorbitol, lower fatty acids, lower amines, and hydrotropes like p-toluenesulfonic acid and ether carboxylic acids, for the purpose of making them liquid. Considering economic efficiency and the viewpoint of obtaining excellent storage stability, the content of the cationic surfactant is preferably 0.02% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.10% by mass or more, and preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less, based on the total mass of the obtained asphalt emulsion.

[0043] (Inorganic salts) In step 2, from the viewpoint of emulsification, an inorganic salt may be further added and mixed. Examples of inorganic salts include sodium chloride, potassium chloride, calcium chloride, and aluminum chloride, with calcium chloride being preferred. The inorganic salt content is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and preferably 3.0% by mass or less, more preferably 2.0% by mass or less, and even more preferably 1.0% by mass or less, based on the total mass of the resulting asphalt emulsion.

[0044] From the viewpoint of emulsification, the addition and mixing in step 2 is preferably carried out using an emulsifier such as a colloid mill, Hallel-type homogenizer, homogenizer, or line mixer. From the viewpoint of emulsification, the asphalt mixture obtained in step 1 is preferably subjected to the addition and mixing in step 2 in a molten state at a temperature of preferably 120°C or higher, more preferably 125°C or higher, even more preferably 130°C or higher, and preferably 160°C or lower, more preferably 155°C or lower, and even more preferably 150°C or lower. The aqueous medium and surfactant are preferably mixed beforehand. From the viewpoint of emulsification, the aqueous medium and surfactant are preferably subjected to the addition and mixing in step 2 at a temperature of 30°C or higher, more preferably 35°C or higher, even more preferably 40°C or higher, and preferably 60°C or lower, more preferably 55°C or lower.

[0045] <Asphalt Emulsion> Thus, an asphalt emulsion is obtained. Asphalt emulsion is generally a substance in which asphalt particles are stably dispersed in water using a surfactant. The present invention also relates to an asphalt emulsion that can be obtained by the above manufacturing method. The asphalt emulsion of the present invention contains composite particles, the composite particles contain asphalt and polyester, and the volume-median particle size (D 50The composite particles are 1 μm to 40 μm in size. The asphalt emulsion is preferably an aqueous dispersion of the above composite particles, and the composite particles are preferably composite particles in which the polyester is dispersed in the asphalt.

[0046] The present invention also encompasses the following aspects: An asphalt emulsion containing asphalt and polyester with a weight-average molecular weight of 2,000 to 100,000.

[0047] (Volume median particle size (D 50 ) and particle size distribution) The median particle size (D) of the composite particles constituting the asphalt emulsion 50 From the viewpoint of weather resistance, the thickness is 1 μm or more and 40 μm or less, preferably 2 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. In this specification, the volume median particle size (D 50 ) refers to the particle size at which the cumulative volume frequency calculated using volume fractions accounts for 50% of the total volume frequency, starting from the smallest particle size. 50 ) can be determined by the method described in the examples below.

[0048] From the viewpoint of weather resistance, the composite particles constituting the asphalt emulsion preferably have a particle size distribution in which the frequency of particles with a size of 500 nm or less is 5% by volume or less, more preferably 2% by volume or less, even more preferably 1% by volume or less, and even more preferably 0.5% by volume or less. The particle size distribution can be determined by the method described in the examples below.

[0049] (Asphalt content) From the viewpoint of weather resistance, the asphalt content in the composite particles constituting the asphalt emulsion is preferably 50% by mass or more, more preferably 75% by mass or more, even more preferably 90% by mass or more, and preferably 99% by mass or less, and more preferably 98% by mass or less. (Polyester content) From the viewpoint of weather resistance, the polyester content in the composite particles constituting the asphalt emulsion is preferably 1 part by mass or more, more preferably 2 parts by mass or more, even more preferably 3 parts by mass or more, and preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, per 100 parts by mass of asphalt. (solid content) From the viewpoint of weather resistance, the solid content of the asphalt emulsion is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. From the viewpoint of emulsification, it is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0050] The asphalt emulsion of the present invention can be used alone or in combination with other additives. For example, it can be suitably used alone for prime coat, tack coat, etc., in accordance with known asphalt emulsions. It can also be suitably used in combination with aggregates, fillers, etc., to produce asphalt mixtures for paving. Because the asphalt emulsion of the present invention contains dispersed asphalt in an unheated state, it can be used in an unheated state, preferably at 150°C or below, more preferably at 100°C or below, and even more preferably at 50°C or below. Therefore, it can be suitably used for asphalt paving at room temperature.

[0051] [Asphalt mixture for paving] The asphalt mixture for paving according to the present invention contains the above-mentioned asphalt emulsion and aggregate. As aggregate, crushed stone, pebbles, gravel, sand, recycled aggregate, ceramics, etc., can be selected and used as desired. The aggregate content is preferably 1,000 parts by mass or more, more preferably 1,200 parts by mass or more, more preferably 1,500 parts by mass or more, per 100 parts by mass of composite particles, and preferably 3,000 parts by mass or less, more preferably 2,500 parts by mass or less, and even more preferably 2,000 parts by mass or less. Since the asphalt mixture for paving according to the present invention contains dispersed asphalt in a non-heated state, it can be manufactured by mixing the above-mentioned composite particles and aggregate in a non-heated state, preferably at 150°C or lower, more preferably at 100°C or lower, and even more preferably at 50°C or lower.

[0052] [Road paving methods] The asphalt mixture for paving according to the present invention can be suitably used for constructing asphalt pavement on roads. The road paving method of the present invention comprises the step of applying the aforementioned paving mixture to a road to form an asphalt paving material layer. The asphalt paving material layer may be either a base layer or a surface layer. The asphalt mixture for paving according to the present invention can be suitably used for room-temperature paving. Specifically, the application temperature is preferably 150°C or lower, more preferably 100°C or lower, and even more preferably 50°C or lower in an unheated state. [Examples]

[0053] In the following preparation examples, manufacturing examples, examples, and comparative examples, "parts" and "%" refer to "parts by mass" and "mass%" respectively, unless otherwise specified.

[0054] (1) Method for measuring the acid value and hydroxyl value of polyester The acid value and hydroxyl value of polyesters were measured according to the method of JIS K0070:1992. However, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070:1992 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)) for polyesters (A1) and (A2), and to a mixed solvent of chloroform and dimethylformamide (chloroform:dimethylformamide = 7:3 (volume ratio)) for polyester (A3).

[0055] (2) Method for measuring the softening point, maximum endothermic peak temperature, and glass transition temperature of polyester (i) Softening point Using a flow tester (Shimadzu Corporation, "CFT-500D"), 1 g of sample was heated at a heating rate of 6°C / min while a load of 1.96 MPa was applied by a plunger and extruded through a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester was plotted against temperature, and the temperature at which half of the sample flowed out was defined as the softening point. (ii) Maximum endothermic peak temperature and glass transition temperature Using a differential scanning calorimeter (TA Instruments Japan Co., Ltd., "Q-100"), 0.01 to 0.02 g of the sample was weighed into an aluminum pan, heated to 200°C, and then cooled to 0°C at a rate of 10°C / min. Next, the heat quantity was measured while heating to 150°C at a rate of 10°C / min. Among the observed endothermic peaks, the temperature of the peak with the largest peak area was defined as the maximum endothermic peak temperature. When no peak was observed but a step was observed, the temperature at the intersection of the tangent line representing the maximum slope of the curve in the step portion and the extension of the baseline on the lower temperature side of the step was defined as the glass transition point.

[0056] (3) Method for measuring the weight-average molecular weight of polyester The molecular weight distribution was measured by gel permeation chromatography (GPC), obtained using the following method, and the weight-average molecular weight was determined. (i) Preparation of sample solution The sample was dissolved in a solvent at 25°C to a concentration of 0.5 g / 100 mL. This solution was then filtered using a fluoropolymer filter with a pore size of 0.2 μm (DISMIC-25JP, manufactured by Toyo Roshi Co., Ltd.) to remove undissolved material and obtain the sample solution. As the solvent, chloroform was used for polyesters (A1) and (A2), and tetrahydrofuran was used for polyester (A3). (ii) Molecular weight measurement Using the measuring apparatus and analytical column described below, the same solvent used to prepare the sample solution was flowed at a flow rate of 1 mL per minute as the eluent, and the column was stabilized in a constant temperature bath at 40°C. 100 μL of the sample solution was injected into the column and measurements were performed. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curve used in this measurement included several types of monodisperse polystyrene "A-500" (5.0 × 10⁻¹⁰). 2 ), "A-1000" (1.01 x 10 3 ), "A-2500" (2.63 x 10 3 ), "A-5000" (5.97 x 10 3 ), "F-1" (1.02×10 3 ), "F-2" (1.81×10 4 ), "F-4" (3.97×10 4 ), "F-10" (9.64×10 4 ), "F-20" (1.90×10 5 ), "F-40" (4.27×10 5 ), "F-80" (7.06×10 5 ), "F-128" (1.09×10 6 The above samples were prepared using Tosoh Corporation's standard sample. Measuring device: "HLC-8220CPC" (manufactured by Tosoh Corporation) Analysis columns: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0057] (4) Method for measuring the polyester dispersion diameter in asphalt mixture A molten asphalt mixture was dropped onto a glass slide, sandwiched between cover slips, and heated at 120°C for 1 minute to obtain a thin layer for measurement. The measurement sample was observed using a digital microscope (Keyence Corporation, "VHX-1000"), and the diameter of 30 polyester particles randomly selected from the field of view was measured by image analysis. The average value was defined as the polyester dispersion diameter.

[0058] (5) Medium particle size of asphalt emulsion (D 50 ) and method for measuring particle size distribution (i) Measuring device: Laser diffraction particle size analyzer "LA-920" (manufactured by Horiba, Ltd.) (ii) Measurement conditions: Distilled water was added to the asphalt emulsion to adjust the concentration to one that could measure the particle size of 30,000 particles in 20 seconds. Then, the 30,000 particles were measured to obtain the particle size distribution. From the obtained particle size distribution, the median particle size by volume (D 50 The frequency of particles with a particle size of 500 nm or less was determined.

[0059] Synthesis Examples 1-2 (Synthesis of Polyester (A1)-(A2)) The 1,6-hexanediol and sebacic acid shown in Table 1 were placed in a 5-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, fall-flow condenser, and nitrogen inlet tube. 20 g of tin(II) di(2-ethylhexanoate) was added under a nitrogen atmosphere, and the temperature was raised from 140°C to 200°C over 7 hours in a mantle heater. After reaching 200°C, a reduced pressure reaction was carried out at 8.0 kPa, and the reaction was continued until the softening point shown in Table 1 was reached to obtain the target polyesters (A1) and (A2). The results are shown in Table 1.

[0060] Synthesis Example 3 (Synthesis of Polyester (A3)) The polyoxypropylene adduct of bisphenol, the polyoxyethylene adduct of bisphenol, terephthalic acid, and dodecenyl succinic anhydride shown in Table 1 were placed in a 5-liter four-necked flask equipped with a stainless steel stirring rod, a drop-through condenser, and a nitrogen inlet tube, and heated to 160°C in a mantle heater under a nitrogen atmosphere. A mixture of styrene, 2-ethylhexyl acrylate, acrylic acid, and dibutyl peroxide was then added dropwise to carry out polymerization. Subsequently, 20 g of tin(II) di(2-ethylhexanoate) and 2 g of gallic acid were added, and the temperature was raised to 235°C over 3 hours, after which it was held for 5 hours. After that, a reduced-pressure reaction was carried out at 8.0 kPa for 1 hour, and then it was cooled to 210°C. At 210°C, trimellitic anhydride was added, and it was held at 210°C for 1 hour, followed by a reduced-pressure reaction at 8.0 kPa. The reaction was then carried out until the softening point shown in Table 1 was reached, yielding the composite resin polyester (A3). The results are shown in Table 1.

[0061] [Table 1]

[0062] Manufacturing Example 1 (Manufacturing of Asphalt Mixture (AS1)) As a binder mixture, 1560g of straight asphalt (manufactured by Cosmo Oil Co., Ltd., penetration 150-200) heated to 180°C was placed in a 3L stainless steel container, and 78g of polyester (A1) obtained in Synthesis Example 1 (5 parts by mass per 100 parts by mass of asphalt) was gradually added. The mixture was stirred at 180°C for 1 hour with an anchor-type stirring blade at 300 rpm to prepare asphalt mixture (AS1). The dispersion diameter of polyester in the asphalt mixture was measured to confirm that polyester was dispersed in the asphalt. The results are shown in Table 2.

[0063] Manufacturing Examples 2-5 and Comparative Manufacturing Example 1 Asphalt mixtures (AS2) to (AS6) were obtained in the same manner as in Production Example 1, except that the conditions shown in Table 2 were changed.

[0064] [Table 2]

[0065] Example 1 (Production of asphalt emulsion (AE1)) As the aqueous phase, 7.2 g (0.3% by mass of the theoretical yield) of a cationic surfactant (Quimi-Kao SA de CV; "Asfire N100L", amine mixture), 780 g of deionized water, and 2.4 g of calcium chloride (0.1% by mass of the theoretical yield) were mixed and the pH was adjusted to 2.0 with 1.0 M hydrochloric acid, and then the total weight of the aqueous phase was adjusted to 840 g with deionized water. 840 g of the aqueous phase heated to 50°C and 1560 g of the asphalt mixture (AS1) obtained in Production Example 1, heated to 140°C, were simultaneously placed in a colloid mill to obtain asphalt emulsion (AE1). The volume-median particle size (D) of the asphalt emulsion was measured. 50The particle size distribution was measured, and the results are shown in Table 3.

[0066] Examples 2-5 and Comparative Example 1 Asphalt emulsions (AE2) to (AE6) were obtained in the same manner as in Example 1, except that the conditions shown in Table 3 were changed. The results are shown in Table 3.

[0067] [Weather resistance evaluation] The weather resistance of the asphalt emulsions (AE1) to (AE6) obtained in the examples and comparative examples was evaluated by the following method. The results are shown in Table 3. (Preparation of samples for weather resistance evaluation) Asphalt emulsion was placed in a disposable dish (Anton Paar, "EMS / TEK500 / 600") in an amount equivalent to 3g of solid content, spread evenly, and then dried in a high-temperature dryer at 60°C for 3 days to obtain a sample for weather resistance evaluation. (UV irradiation degradation acceleration test) The weather resistance evaluation samples obtained above were placed in an accelerated weathering tester (Suga Test Instruments Co., Ltd., "Super Xenon Weather Meter SX75") and subjected to a UV intensity of 120 W / m². 2 A UV irradiation degradation acceleration test was conducted by scanning with an irradiation wavelength of 300-400 nm, chamber temperature of 40°C, humidity of 75%, panel temperature of 65°C, and irradiation time of 100 hours. (Tanδ measurement before and after UV irradiation) Dynamic viscoelasticity measurements were performed on samples before and after UV irradiation using a viscoelasticity analyzer (Anton Paar, "MCR301"). A 1g weather-resistant sample heated to 120°C was placed in a disposable dish (Anton Paar, EMS / TEK500 / 600) fixed to the measuring device using a dedicated jig (Anton Paar, P-PTD200 / 62). Dynamic viscoelasticity was measured using a 25mm disposable flat plate (Anton Paar, PP25) with a gap of 1.0mm, strain of 0.1%, and frequency of 1.0Hz. A mold temperature control unit at the bottom of the sample was used for temperature control, and tanδ was measured at 20°C when the sample was cooled from 120°C to 0°C at a cooling rate of 5°C / min. The rate of change of tanδ was calculated according to the following formula, and the weather resistance was evaluated. The closer the rate of change is to 100%, the less degradation due to ultraviolet irradiation is observed, indicating superior weather resistance. The test results are shown in Table 3. Rate of change of tanδ = [(tanδ after UV irradiation) / (tanδ before UV irradiation)] × 100

[0068] [Table 3]

[0069] Table 3 shows that the asphalt emulsions obtained in Examples 1 to 5 exhibit excellent weather resistance. Because the asphalt emulsion of the present invention has excellent weather resistance, it can be expected to suppress the occurrence of cracks.

Claims

1. A method for producing an asphalt emulsion, comprising the following steps 1 and 2, Step 1: A process of melting and mixing asphalt and polyester to obtain an asphalt mixture. Step 2: Adding and mixing an aqueous medium and a surfactant to the asphalt mixture obtained in Step 1. A method for producing an asphalt emulsion, wherein the polyester comprises a structural unit derived from an alcohol component containing 70 mol% or more of an α,ω-aliphatic diol having 4 to 16 carbon atoms, and a structural unit derived from a carboxylic acid component containing 70 mol% or more of an aliphatic dicarboxylic acid having 4 to 14 carbon atoms.

2. The solubility parameter (SP value) of the polyester is 12 (cal / cm³). 3 ) 1 / 2 The method for producing an asphalt emulsion according to claim 1 is as follows:

3. The method for producing an asphalt emulsion according to claim 1 or 2, wherein the solubility parameter (SP value) of the polyester is 8 (cal / cm³) 1 / 2 or more and 10 (cal / cm³) 1 / 2 or less.

4. The method for producing an asphalt emulsion according to any one of claims 1 to 3, wherein the melting and mixing temperature is 130°C or higher and 220°C or lower.

5. A method for producing an asphalt emulsion according to any one of claims 1 to 4, wherein the weight-average molecular weight of the polyester is 2,000 or more and 100,000 or less.

6. An asphalt emulsion containing composite particles, The composite particles contain asphalt and polyester, and have a medium volume particle size (D 50 ) are composite particles with a size of 1 μm or more and 40 μm or less. An asphalt emulsion wherein the polyester comprises a structural unit derived from an alcohol component containing 70 mol% or more of an α,ω-aliphatic diol having 4 to 16 carbon atoms, and a structural unit derived from a carboxylic acid component containing 70 mol% or more of an aliphatic dicarboxylic acid having 4 to 14 carbon atoms.

7. The asphalt emulsion according to claim 6, wherein the particle frequency of particles with a particle size of 500 nm or less in the particle size distribution is 5% by volume or less.

8. The solubility parameter (SP value) of the polyester is 12 (cal / cm³). 3 ) 1 / 2 The asphalt emulsion according to claim 6 or 7, which is as follows:

9. The asphalt emulsion according to any one of claims 6 to 8, wherein the solubility parameter (SP value) of the polyester is 8 (cal / cm³) 1 / 2 or more and 10 (cal / cm³) 1 / 2 or less.

10. A paving asphalt mixture containing the asphalt emulsion and aggregate described in any one of claims 6 to 9.

11. A road paving method comprising the step of applying the asphalt mixture for paving described in claim 10 to a road at a temperature of 150°C or lower.

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