Asphalt composition

Abstract

To provide an asphalt modifying agent that can achieve asphalt pavement having excellent water resistance even under high-temperature conditions.SOLUTION: An asphalt composition contains asphalt and an asphalt modifying agent, wherein the asphalt modifying agent contains a polyester amide containing a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component and a structural unit derived from a polyamide component.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an asphalt composition, an asphalt mixture and a method for producing the same, an asphalt modifier and a method for producing the same, and a road paving method. [Background technology]

[0002] BACKGROUND ART Asphalt pavements using asphalt compositions are used for paving roads, parking lots, freight yards, sidewalks, etc. because they are relatively easy to lay and require a short time from the start of paving work until traffic can begin. Asphalt pavement has a road surface formed from an asphalt mixture in which aggregate is bound with asphalt, so the paved road has good hardness and durability. However, asphalt pavement surfaces develop ruts and cracks over time, necessitating repairs, which increases maintenance costs and has a significant impact on automobile traffic.

[0003] Patent Document 1 discloses an asphalt composition for road paving that has excellent dry strength, water immersion strength, and petroleum immersion strength. The asphalt composition contains asphalt, a specific amount of polyester resin, and aggregate, where the polyester resin is a polyester having structural units derived from an alcohol component including a specific amount of an alkylene oxide adduct of bisphenol A and structural units derived from a carboxylic acid component including a specific amount of one or more acids selected from terephthalic acid and isophthalic acid, and has a specific softening point and hydroxyl value. Patent Document 2 discloses a waterproof layer material used in a waterproof layer formed for waterproofing a structure, which contains a polyamide resin having a specific softening point and a specific melt viscosity at 180°C, and which has excellent high-temperature shear strength without compromising low-temperature shear strength and is also easy to work with. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 125421 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-217044 Summary of the Invention [Problem to be solved by the invention]

[0005] If asphalt pavement exposed to rainwater or other elements does not have sufficient water resistance, moisture can penetrate and remain between the asphalt and aggregate, peeling off the asphalt coating on the aggregate surface. This, combined with the load caused by vehicle traffic, can cause the asphalt pavement to turn into gravel. The technology described in Patent Document 1 exhibits excellent water resistance up to temperatures of 50°C, but even greater water resistance under high-temperature conditions of 60°C or higher is desired. Patent Document 2 does not relate to problems in asphalt pavement. The present invention relates to an asphalt composition that can provide an asphalt pavement that is excellent in water resistance even under high-temperature conditions, an asphalt modifier and a method for producing the same, an asphalt mixture and a method for producing the same, and a road paving method. [Means for solving the problem]

[0006] The present invention relates to the following [1] to [6]. [1] An asphalt composition containing asphalt and an asphalt modifier, The asphalt composition, wherein the asphalt modifier comprises a polyesteramide containing structural units derived from an alcohol component, structural units derived from a carboxylic acid component, and structural units derived from a polyamide component. [2] An asphalt mixture comprising the asphalt composition according to [1] above and aggregate. [3] An asphalt modifier comprising a polyesteramide containing structural units derived from an alcohol component, structural units derived from a carboxylic acid component, and structural units derived from a polyamide component. [4] A method for producing the asphalt modifier described in [3] above, comprising the following step 1: Step 1: Polycondensation of an alcohol component, a carboxylic acid component, and a polyamide component to obtain a polyesteramide [5] A method for producing an asphalt mixture according to [2] above, comprising the following steps 1 and 2: Step 1: Polycondensation of an alcohol component, a carboxylic acid component, and a polyamide component to obtain a polyesteramide Step 2: Mixing the heated aggregate, asphalt, and polyesteramide obtained in step 1 [6] A road paving method comprising the step of applying the asphalt mixture described in [2] above to a road to form an asphalt pavement layer. [Effects of the Invention]

[0007] The present invention can provide an asphalt composition, an asphalt modifier and a method for producing the same, an asphalt mixture and a method for producing the same, and a road paving method that can provide an asphalt pavement that is excellent in water resistance even under high-temperature conditions. DETAILED DESCRIPTION OF THE INVENTION

[0008] The asphalt composition of the present invention contains asphalt and a polyesteramide as an asphalt modifier. The asphalt modifier can be used alone or in combination of two or more kinds. The asphalt modifier contained in the asphalt composition and its manufacturing method, the asphalt composition and its manufacturing method, the asphalt mixture and its manufacturing method, and the road paving method will be described below in that order.

[0009] [Asphalt modifier] The asphalt modifier of the present invention comprises a polyesteramide containing structural units derived from an alcohol component, structural units derived from a carboxylic acid component, and structural units derived from a polyamide component. By incorporating an asphalt modifier consisting of a polyesteramide containing structural units derived from an alcohol component, structural units derived from a carboxylic acid component, and structural units derived from a polyamide component into an asphalt composition or asphalt mixture, an asphalt composition or asphalt mixture having excellent water resistance even under high temperature conditions can be obtained.

[0010] The reason why the present invention has an effect is not clear, but is thought to be as follows. In general, in asphalt pavement, asphalt coats aggregates and bonds them together. In the technology described in Patent Document 1, the ester groups of polyester in the asphalt interact with polar groups such as silanol groups on the aggregate surface through hydrogen bonding, improving adhesion between the aggregates and providing water resistance. However, under high temperature conditions of 60°C or higher, the movement of polyester molecular chains and water molecules becomes more intense, and the intrusion of water molecules onto the aggregate surface inhibits the interaction between the aggregate surface and the polyester, making it difficult to provide water resistance. In the present invention, polyesteramides, which incorporate amide groups into polyester, are presumed to exhibit water resistance even under high-temperature conditions because the amide groups interact more strongly with the aggregate at multiple points through hydrogen bonds and are less susceptible to interaction inhibition by the intervention of water molecules even under high-temperature conditions.

[0011] The definitions of various terms used in this specification are shown below. In polyesteramides, a "structural unit derived from an alcohol component" means a structure in which a hydrogen atom is removed from a hydroxy group of an alcohol component, and a "structural unit derived from a carboxylic acid component" means a structure in which a hydroxy group is removed from a carboxy group of a carboxylic acid component. The term "carboxylic acid component" is a concept that includes not only the carboxylic acid itself, but also anhydrides that decompose during the reaction to produce an acid, and alkyl esters of carboxylic acids (for example, alkyl groups having 1 to 3 carbon atoms). When the carboxylic acid component is an alkyl ester of carboxylic acid, the number of carbon atoms of the alkyl group that is the alcohol residue of the ester is not counted in the number of carbon atoms of the carboxylic acid component.

[0012] [Polyesteramide] The polyesteramide constituting the asphalt modifier of the present invention contains constituent units derived from an alcohol component, constituent units derived from a carboxylic acid component, and constituent units derived from a polyamide component. The polyesteramide is a polycondensate obtained by polycondensation of an alcohol component, a carboxylic acid component, and a polyamide component. That is, the asphalt modifier of the present invention can be obtained by a production method including the following step 1. Step 1: Polycondensation of an alcohol component, a carboxylic acid component, and a polyamide component to obtain a polyesteramide The physical properties of the alcohol component, the carboxylic acid component, the polyamide component, and the polyesteramide will be described below.

[0013] <Alcohol content> Examples of the alcohol component include aliphatic diols, aromatic diols, trihydric or higher polyhydric alcohols, etc. These alcohol components can be used alone or in combination of two or more.

[0014] The aliphatic diol is preferably a linear or branched aliphatic diol having from 2 to 12 carbon atoms, more preferably a linear or branched aliphatic diol having from 2 to 8 carbon atoms. Specific examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,10-decanediol, and 1,12-dodecanediol.

[0015] An example of the aromatic diol is an alkylene oxide adduct of bisphenol A. An example of the alkylene oxide adduct of bisphenol A is an alkylene oxide adduct of bisphenol A represented by the following formula (I).

[0016] [ka]

[0017] [In the formula, OR 1 and R 1 O is alkylene oxide and R 1 is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers indicating the average number of moles of alkylene oxide added, and the sum of x and y is preferably 1 or more, more preferably 1.5 or more, and is preferably 16 or less, more preferably 8 or less, and even more preferably 4 or less.

[0018] Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0019] The alcohol component may further contain a monohydric aliphatic alcohol from the viewpoint of adjusting physical properties. Examples of the monohydric aliphatic alcohol include lauryl alcohol, myristyl alcohol, palmityl alcohol, and stearyl alcohol. These monohydric aliphatic alcohols may be used alone or in combination of two or more.

[0020] From the viewpoint of water resistance at high temperatures, the alcohol component preferably contains an alkylene oxide adduct of bisphenol A, and more preferably contains an alkylene oxide adduct of bisphenol A represented by the above formula (I).

[0021] Examples of the alkylene oxide adduct of bisphenol A represented by the formula (I) include a propylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane and an ethylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane. These alkylene oxide adducts of bisphenol A can be used alone or in combination of two or more. Among these, a combination of a propylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane and an ethylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane is preferred.

[0022] In terms of water resistance at high temperatures, the amount of alkylene oxide adduct of bisphenol A in the alcohol component is 65 mol % or more, more preferably 75 mol % or more, more preferably 90 mol % or more, and even more preferably 100 mol %.

[0023] The molar ratio of the propylene oxide adduct of bisphenol A to the ethylene oxide adduct of bisphenol A is preferably 10 / 90 or more, more preferably 20 / 80 or more, and even more preferably 30 / 70 or more, from the viewpoints of the dry strength and water resistance of the asphalt pavement, and is preferably 70 / 30 or less, more preferably 60 / 40 or less, and more preferably 50 / 50 or less, from the viewpoints of the dry strength, water resistance, and oil resistance of the asphalt pavement.

[0024] <Carboxylic acid component> Examples of the carboxylic acid component include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and polycarboxylic acids having a valence of 3 to 6. These carboxylic acid components can be used alone or in combination of two or more.

[0025] The aliphatic dicarboxylic acid preferably has 4 or more carbon atoms in the main chain and 10 or less, more preferably 8 or less, and more preferably 6 or less, such as fumaric acid, maleic acid, oxalic acid, malonic acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, or anhydrides or alkyl esters thereof (e.g., alkyl groups having 1 to 3 carbon atoms). Examples of substituted succinic acids include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid.

[0026] Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, anhydrides thereof, and alkyl esters thereof (for example, alkyl groups having 1 to 3 carbon atoms). Of these aromatic dicarboxylic acids, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred, from the viewpoint of reducing the amount of microplastics generated.

[0027] The trivalent or more and hexavalent polycarboxylic acid is preferably a trivalent carboxylic acid. Examples of the trivalent or more and hexavalent polycarboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and acid anhydrides thereof.

[0028] The carboxylic acid component may further contain a monovalent aliphatic carboxylic acid from the viewpoint of adjusting physical properties. Examples of the monovalent aliphatic carboxylic acid include monovalent aliphatic carboxylic acids having from 12 to 20 carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, and alkyl (having from 1 to 3 carbon atoms) esters of these acids. These monovalent aliphatic carboxylic acids may be used alone or in combination of two or more.

[0029] From the viewpoint of water resistance at high temperatures, the carboxylic acid component preferably contains at least one selected from terephthalic acid and isophthalic acid, and more preferably contains terephthalic acid. The content of one or more selected from terephthalic acid and isophthalic acid in the carboxylic acid component is 50 mol% or more, preferably 60 mol% or more, preferably 80 mol% or more, and more preferably 100 mol%, from the viewpoints of melt dispersibility in asphalt and dry strength of asphalt pavement.

[0030] <Polyamide component> Examples of polyamides include aliphatic polyamides and aromatic polyamides. Examples of polyamides include polyamides made from polycondensates of diamines and dicarboxylic acids, polyamides made from polycondensates of lactams, polyamides made from polycondensates of aminocarboxylic acids, and polyamides made from copolymers of lactams and aminocarboxylic acids.

[0031] Examples of the diamine include aliphatic diamines and diamines having an aromatic or cyclic structure. Examples of the aliphatic diamine include tetramethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, undecamethylenediamine, and dodecamethylenediamine. Examples of diamines having an aromatic or cyclic structure include metaxylylenediamine.

[0032] Examples of dicarboxylic acids include aliphatic dicarboxylic acids and dicarboxylic acids having an aromatic or cyclic structure. Examples of the aliphatic dicarboxylic acid include adipic acid, heptanedicarboxylic acid, octanedicarboxylic acid, nonanedicarboxylic acid, undecanedicarboxylic acid, and dodecanedicarboxylic acid. Examples of dicarboxylic acids having an aromatic or cyclic structure include terephthalic acid and isophthalic acid.

[0033] Examples of lactams include lactams having from 6 to 12 carbon atoms, and examples of aminocarboxylic acids include aminocarboxylic acids having from 6 to 12 carbon atoms, such as 6-aminocaproic acid, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, α-pyrrolidone, ε-caprolactam, ω-laurolactam, ε-enantholactam, and lauryllactam.

[0034] Aliphatic polyamides include polycapramide (nylon 6), poly-ω-aminoheptanoic acid (nylon 7), poly-ω-aminononanoic acid (nylon 9), polyundecaneamide (nylon 11), polylauryl lactam (nylon 12), polyethylenediamine adipamide (nylon 2,6), polytetramethylene adipamide (nylon 4,6), polyhexamethylene adipamide (nylon 6,6), polyhexamethylene sebacamide (nylon 6,10), polyhexamethylene dodecamide (nylon 6,12), polyoctamethylene adipamide (nylon 8,6), polydecamethylene adipamide (nylon 10,8), caprolactam / lauryl lactam copolymer (nylon 6 / 12), caprolactam / ω-amino Examples of such aliphatic nylons and their copolymers include nonanoic acid copolymer (nylon 6 / 9), caprolactam / hexamethylenediammonium adipate copolymer (nylon 6 / 6,6), lauryllactam / hexamethylenediammonium adipate copolymer (nylon 12 / 6,6), ethylenediamine adipamide / hexamethylenediammonium adipate copolymer (nylon 2,6 / 6,6), caprolactam / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6,6 / 6,10), and ethyleneammonium adipate / hexamethylenediammonium adipate / hexamethylenediammonium sebacate copolymer (nylon 6 / 6,6 / 6,10). Among these, nylon 6, nylon 6, and nylon 6 / 6,6 (a copolymer of nylon 6 and nylon 6,6) are preferred. Examples of aromatic polyamides include crystalline aromatic polyamides obtained by polycondensation of aromatic diamines such as metaxylylenediamine and paraxylylenediamine with dicarboxylic acids or derivatives thereof such as adipic acid, suberic acid, sebacic acid, cyclohexanedicarboxylic acid, terephthalic acid, and isophthalic acid. Among these, preferred are crystalline aromatic polyamides such as polymetaxylyleneadipamide (MXD-nylon).

[0035] From the viewpoint of water resistance at high temperatures, the polyamide component preferably contains an aliphatic polyamide, more preferably one or more selected from nylon 6, nylon 2,6, nylon 4,6, nylon 6,6 and nylon 12, even more preferably one or more selected from nylon 6, nylon 6,6 and nylon 12, and even more preferably one or more selected from nylon 6 and nylon 6,6. In terms of water resistance at high temperatures, the content of one or more selected from nylon 6 and nylon 6,6 in the polyamide component is 50 mol % or more, preferably 60 mol % or more, preferably 80 mol % or more, and more preferably 100 mol %.

[0036] <Molar ratio of structural units derived from carboxylic acid components to structural units derived from alcohol components> From the viewpoint of adjusting the hydroxyl value, the molar ratio of the structural units derived from the carboxylic acid component to the structural units derived from the alcohol component in the polyesteramide [carboxylic acid component / alcohol component] is preferably 0.7 or more, more preferably 0.8 or more, and is preferably 1.5 or less, more preferably 1.3 or less, more preferably 1.1 or less, and more preferably less than 1.0.

[0037] <Molar ratio of structural units derived from the alcohol component to amide bonds in the polyamide component> In view of water resistance under high temperature conditions, the molar ratio of the structural units derived from the alcohol component to the amide bonds in the polyamide component in the polyesteramide (alcohol component / amide bond) (A / N ratio) is preferably 40 / 60 or more, more preferably 60 / 40 or more, and is preferably 95 / 5 or less, more preferably 93 / 7 or less, and even more preferably 90 / 10 or less. The A / N ratio may also be 70 / 30 or more, or 80 / 20 or more.

[0038] <Physical properties of polyesteramide> From the viewpoint of the dry strength of the asphalt pavement, the acid value of the polyesteramide is preferably 2 mgKOH / g or more, more preferably 3 mgKOH / g or more, even more preferably 4 mgKOH / g or more, and is preferably 40 mgKOH / g or less, more preferably 30 mgKOH / g or less, even more preferably 20 mgKOH / g or less. From the viewpoint of the dry strength of the asphalt pavement, the hydroxyl value of the polyesteramide is preferably 1 mgKOH / g or more, more preferably 2 mgKOH / g or more, and even more preferably 5 mgKOH / g or more, and from the viewpoint of improving the dry strength and water immersion strength, it is preferably 50 mgKOH / g or less, and preferably 30 mgKOH / g or less.

[0039] The softening point of the polyesteramide is preferably 85°C or higher, more preferably 90°C or higher, and even more preferably 95°C or higher, from the viewpoint of exhibiting high adhesive strength to aggregate and improving dry strength, and is preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower, from the viewpoint of excellent melt dispersibility in asphalt and improving dry strength. The glass transition point of the polyesteramide is preferably 30°C or higher, more preferably 40°C or higher, and even more preferably 45°C or higher, from the viewpoint of improving dry strength, and is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower, from the viewpoint of excellent melt dispersibility in asphalt and improving dry strength.

[0040] The polyesteramide has a solubility in toluene at 20°C of preferably 10 g / L or more, more preferably 15 g / L or more, and even more preferably 20 g / L or more, from the viewpoint of excellent melt dispersibility in asphalt and improving dry strength. As shown in the Examples, the solubility in toluene at 20°C can be measured by dissolving a predetermined amount of polyesteramide in a predetermined amount of toluene, and determining whether or not a precipitate is formed when the solution is allowed to stand for a predetermined period of time.

[0041] The 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. The acid value, hydroxyl value, softening point, and glass transition point can be measured by the methods described in the Examples below.

[0042] <Method of producing polyesteramide> The method for producing polyesteramide is not particularly limited, but it can be produced, for example, by polycondensing the above-mentioned alcohol component, carboxylic acid component, and polyamide component. There is no particular restriction on the timing of adding the polyamide component, but it is preferable to add it together with the alcohol component and the carboxylic acid component before the start of the reaction. From the viewpoint of reactivity, the temperature of the polycondensation reaction is preferably 160°C or higher, more preferably 190°C or higher, even more preferably 220°C or higher, and preferably 260°C or lower, more preferably 250°C or lower, even more preferably 240°C or lower.

[0043] In the polycondensation reaction, from the viewpoint of reaction rate, a tin(II) compound having no Sn-C bond, such as tin(II) di(2-ethylhexanoate), can be used as an esterification catalyst. From the viewpoint of reaction rate, the amount of the 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, even more preferably 0.6 parts by mass or less, per 100 parts by mass of the total amount of the alcohol component, carboxylic acid component, and polyamide component. In addition to the esterification catalyst, a pyrogallol compound such as gallic acid can be used as a co-catalyst in the polycondensation reaction from the viewpoint of reaction rate. From the viewpoint of reaction rate, the amount of the co-catalyst used is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, even more preferably 0.01 part by mass or more, and preferably 0.15 part by mass or less, more preferably 0.10 part by mass or less, even more preferably 0.05 part by mass or less, per 100 parts by mass of the total amount of the alcohol component, carboxylic acid component, and polyamide component. In addition to the catalyst, a polymerization inhibitor such as tertiary butyl catechol can be used in the polycondensation reaction from the viewpoint of reaction rate. From the viewpoint of reaction rate, the amount of the polymerization inhibitor used is preferably 0.001 part by mass or more, more preferably 0.01 part by mass or more, and preferably 0.5 part by mass or less, more preferably 0.2 part by mass or less, per 100 parts by mass of the total amount of the alcohol component, the carboxylic acid component, and the polyamide component.

[0044] In the method for producing polyesteramide, preferably, in a spectrum obtained by infrared spectroscopy (IR), the polyamide component has a peak at 1630 cm before the polycondensation reaction. -1 ~1640cm -1 At 1630 cm, a peak due to the amide C=O stretching vibration of the polyamide is observed. However, after the polycondensation reaction, the peak due to the amide C=O stretching vibration shifts, and the peak at 1630 cm -1 ~1640cm -1 The peak is no longer observed in the region. Therefore, the polyesteramide constituting the asphalt modifier of the present invention preferably has a peak at 1630 cm in a spectrum obtained by infrared spectroscopy (IR). -1 ~1640cm -1 The peak due to the amide C=O stretching vibration is not observed. Infrared spectroscopy (IR) spectra are measured using a Nicolet Summit FT-IR spectrophotometer manufactured by Thermo Fisher Scientific.

[0045] The asphalt modifier of the present invention may contain components other than the polyesteramide as long as the effects are not impaired, or may consist solely of the polyesteramide. The content of polyesteramide in the asphalt modifier is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the asphalt modifier.

[0046] The asphalt modifier of the present invention can be used, for example, by mixing with asphalt to obtain an asphalt composition. Heated aggregate is added to the obtained asphalt composition to form an asphalt mixture, which can then be used for paving. The asphalt modifier of the present invention can be suitably used as a modifier to be blended into asphalt mixtures containing aggregate.

[0047] [Asphalt composition] The asphalt composition of the present invention contains asphalt and the above-mentioned asphalt modifier (polyesteramide). The asphalt modifiers can be used alone or in combination of two or more. The content of the asphalt modifier (polyesteramide) is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, per 100 parts by mass of the asphalt, from the viewpoint of accelerating the development of water resistance, and from the viewpoint of workability, it is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 15 parts by mass or less.

[0048] <Asphalt> Various types of asphalt can be used. Examples include straight asphalt, which is petroleum asphalt for paving, as well as modified asphalt. Examples of modified asphalt include blown asphalt and polymer-modified asphalt modified with polymeric materials such as thermoplastic elastomers and thermoplastic resins. Straight asphalt refers to the residual bituminous material obtained by subjecting crude oil to atmospheric distillation equipment, vacuum distillation equipment, etc. Blown asphalt refers to asphalt obtained by heating a mixture of straight asphalt and heavy oil and then blowing air into it to oxidize it. The asphalt is preferably selected from straight asphalt and polymer-modified asphalt, with modified asphalt being more preferred from the viewpoint of durability of the asphalt pavement and straight asphalt being more preferred from the viewpoint of versatility.

[0049] (thermoplastic elastomer) Examples of thermoplastic elastomers in polymer-modified asphalt include styrene / butadiene block copolymers (hereinafter also referred to as "SB"), styrene / butadiene / styrene block copolymers (hereinafter also referred to as "SBS"), styrene / butadiene random copolymers (hereinafter also referred to as "SBR"), styrene / isoprene block copolymers (hereinafter also referred to as "SI"), styrene / isoprene / styrene block copolymers (hereinafter also referred to as "SIS"), styrene / isoprene random copolymers (hereinafter also referred to as "SIR"), ethylene / vinyl acetate copolymers, ethylene / acrylic acid ester copolymers, styrene / ethylene / butylene / styrene copolymers, styrene / ethylene / propylene / styrene copolymers, polyurethane-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, isobutylene / isoprene copolymers, polyisoprene, polychloroprene, synthetic rubbers other than those mentioned above, and at least one selected from natural rubber.

[0050] Among these, from the viewpoint of durability of asphalt pavement, the thermoplastic elastomer is preferably at least one selected from SB, SBS, SBR, SI, SIS, SIR, and ethylene / acrylic acid ester copolymer, more preferably at least one selected from SB, SBS, SBR, SI, SIS, and SIR, and even more preferably at least one selected from SBR and SBS. From the viewpoint of the durability of the asphalt pavement, the content of thermoplastic elastomer in the polymer modified asphalt is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and preferably 30% by mass or less, more preferably 15% by mass or less, even more preferably 5% by mass or less.

[0051] The asphalt content in the asphalt composition is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, from the viewpoint of exhibiting asphalt performance, and is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, from the viewpoint of storage stability.

[0052] [Method for producing asphalt composition] The method for producing an asphalt composition of the present invention includes a step of mixing asphalt with the asphalt modifier (polyesteramide). That is, the asphalt composition of the present invention is an asphalt composition obtained by blending asphalt and the asphalt modifier. The asphalt composition can be obtained by heating and melting asphalt, adding an asphalt modifier, and stirring and mixing the components until they are uniformly dispersed using a commonly used mixer, such as a homomixer, dissolver, paddle mixer, ribbon mixer, screw mixer, planetary mixer, vacuum countercurrent mixer, roll mill, or twin-screw extruder.

[0053] The mixing temperature of the asphalt and the asphalt modifier is preferably 130°C or higher, more preferably 150°C or higher, even more preferably 170°C or higher, from the viewpoint of uniformly dispersing the polyesteramide that constitutes the asphalt modifier in the asphalt, and is preferably 230°C or lower, even more preferably 210°C or lower, more preferably 200°C or lower. Furthermore, the mixing time between the asphalt and the asphalt modifier is preferably 30 seconds or longer, more preferably 1 minute or longer, and even more preferably 2 minutes or longer, from the viewpoint of efficiently dispersing the polyesteramide that constitutes the asphalt modifier uniformly in the asphalt, and is preferably 2 hours or shorter, more preferably 1 hour or shorter, and even more preferably 30 minutes or shorter. The asphalt composition of the present invention is a binder composition, and can be used for paving after, for example, adding aggregate to the asphalt composition to form an asphalt mixture. In other words, the asphalt composition of the present invention is suitable for paving, and particularly suitable for road paving.

[0054] [Asphalt mixture] The asphalt mixture of the present invention contains aggregate and the asphalt composition described above. That is, the asphalt mixture contains at least aggregate, asphalt, and the asphalt modifier (polyesteramide).

[0055] The content of the asphalt modifier (polyesteramide) in the asphalt mixture is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.10% by mass or more, even more preferably 0.15% by mass or more, and preferably 4% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, even more preferably 1% by mass or less. The asphalt content in the asphalt mixture is preferably 2.5% by mass or more, more preferably 3% by mass or more, even more preferably 3.5% by mass or more, even more preferably 4% by mass or more, and preferably 10% by mass or less, more preferably 9% by mass or less, even more preferably 8% by mass or less, even more preferably 7% by mass or less.

[0056] <Aggregate> The aggregate can be selected from crushed stone, boulders, gravel, sand, recycled aggregate, ceramics, etc. In addition, the aggregate can be either coarse aggregate with a particle size of 2.36 mm or more, or fine aggregate with a particle size of less than 2.36 mm. Examples of coarse aggregate include crushed stone with a particle size range of 2.36 mm or more and less than 4.75 mm, crushed stone with a particle size range of 4.75 mm or more and less than 12.5 mm, crushed stone with a particle size range of 12.5 mm or more and less than 19 mm, and crushed stone with a particle size range of 19 mm or more and less than 31.5 mm. The fine aggregate preferably has a particle size of 0.075 mm or more and less than 2.36 mm. Examples of fine aggregate include river sand, dune sand, mountain sand, sea sand, crushed sand, fine sand, screenings, crushed stone dust, silica sand, artificial sand, glass cullet, foundry sand, and recycled crushed aggregate sand. The above particle size is a value specified in JIS A5001:2008. Among these, a combination of coarse aggregate and fine aggregate is preferred.

[0057] The fine aggregate may contain a filler with a particle size of less than 0.075 mm. Examples of fillers include sand, fly ash, calcium carbonate such as limestone powder, and slaked lime. Among these, calcium carbonate is preferred from the viewpoint of improving the strength of the asphalt pavement. From the viewpoint of improving the strength of the asphalt pavement, the average particle size of the filler is preferably 0.001 mm or more, and preferably 0.05 mm or less, more preferably 0.03 mm or less, and even more preferably 0.02 mm or less. Here, the average particle size is the average particle size at 50% cumulative volume (D 50 ) and can be measured using a laser diffraction particle size distribution analyzer.

[0058] From the viewpoint of water resistance under high temperature conditions, the aggregate preferably contains powder components with a particle size of 150 μm or less in amount of 8% by mass or more, more preferably 8.5% by mass or more, even more preferably 9% by mass or more, and preferably 15% by mass or less, more preferably 12% by mass or less, even more preferably 10% by mass or less. The powder component having a particle size of 150 μm or less includes filler having a particle size of less than 0.075 mm, and fine aggregate having a particle size of 0.075 mm or more and 0.150 mm or less.

[0059] From the viewpoint of durability of the asphalt pavement, the mass ratio of coarse aggregate to fine aggregate is preferably 10 / 90 or more, more preferably 15 / 85 or more, even more preferably 20 / 80 or more, and is preferably 90 / 10 or less, more preferably 80 / 20 or less, even more preferably 70 / 30 or less.

[0060] The aggregate content in the asphalt mixture is preferably 90% by mass or more, preferably 92% by mass or more, preferably 93% by mass or more, and preferably 98% by mass or less, preferably 97% by mass or less, preferably 96% by mass or less.

[0061] Suitable examples of blending in asphalt mixtures include the following (1) to (3). (1) Fine-grained asphalt containing 30% by volume or more but less than 45% by volume of coarse aggregate, 30% by volume or more but less than 50% by volume of fine aggregate, and 5% by volume or more but less than 10% by volume of an asphalt composition. (2) An example of an asphalt mixture is a dense-graded asphalt mixture containing, for example, 45% by volume or more but less than 70% by volume of coarse aggregate, 20% by volume or more but less than 45% by volume of fine aggregate, and 3% by volume or more but less than 10% by volume of an asphalt composition. (3) Porous asphalt containing 70% by volume or more and 80% by volume or less of coarse aggregate, 10% by volume or more and 20% by volume or less of fine aggregate, and 3% by volume or more and 10% by volume or less of an asphalt composition. The asphalt mixing ratio in conventional asphalt mixtures containing aggregate and asphalt is usually determined according to the optimal amount of asphalt determined from the "Mix Design of Asphalt Compositions" described in the "Guidelines for Pavement Design and Construction" published by the Japan Road Association, a public interest incorporated association. In the present invention, the above-mentioned optimum amount of asphalt corresponds to the total amount of asphalt and asphalt modifier. However, it is not necessary to be limited to the method described in the "Guidelines for Pavement Design and Construction" and other methods may be used to determine the amount of asphalt.

[0062] [Asphalt mixture manufacturing method] The method for producing an asphalt mixture of the present invention includes a step of mixing heated aggregate, asphalt, and polyesteramide obtained by polycondensation of an alcohol component, a carboxylic acid component, and a polyamide component. That is, the asphalt mixture of the present invention is an asphalt mixture containing asphalt, aggregate, and the asphalt modifier described above. In the mixing step, the heated aggregate, asphalt, and polyamide can be mixed simultaneously or in any order.

[0063] A preferred embodiment of the method for producing an asphalt mixture includes the following steps 1 and 2. Step 1: Polycondensation of an alcohol component, a carboxylic acid component, and a polyamide component to obtain a polyesteramide Step 2: Mixing the heated aggregate, asphalt, and polyesteramide obtained in step 1 The step 1 of obtaining a polyesteramide can be carried out by the above-mentioned method for producing a polyesteramide.

[0064] Specific methods for producing asphalt mixtures include conventional methods known as the plant mix method and the premix method, both of which involve adding asphalt and an asphalt modifier to heated aggregate. The mixing step is preferably any one of the following steps (i) to (iii). (i) A method in which heated aggregate and asphalt are mixed to obtain a mixture, and then the mixture is mixed with an asphalt modifier. (ii) A method in which asphalt and asphalt modifier are simultaneously added to and mixed with heated aggregate. (iii) A method in which a premixed mixture of asphalt and asphalt modifier is added to and mixed with heated aggregate. Among these, method (i) is preferred from the viewpoint of durability of the asphalt pavement.

[0065] In methods (i) to (iii), the temperature of the heated aggregate is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, from the viewpoint of durability of the asphalt pavement, and is preferably 230°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower, from the viewpoint of preventing thermal degradation of the asphalt.

[0066] From the viewpoint of durability of the asphalt pavement, the mixing temperature is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, and from the viewpoint of preventing thermal degradation of the asphalt, it is preferably 230°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower. The mixing time is not particularly limited, but is preferably 30 seconds or more, more preferably 1 minute or more, even more preferably 2 minutes or more, and is preferably 2 hours or less, more preferably 1 hour or less, even more preferably 30 minutes or less.

[0067] From the viewpoint of durability of the asphalt pavement, the method for producing an asphalt mixture preferably includes a step of mixing asphalt, aggregate, and asphalt modifier, and then holding the resulting asphalt mixture at the above-mentioned mixing temperature or a temperature higher than the mixing temperature. In the step of holding the asphalt mixture, the mixture may be further mixed. The retention time is preferably 0.25 hours or more, more preferably 0.5 hours or more, and even more preferably 1 hour or more, and the upper limit of the time is not particularly limited, but is, for example, about 5 hours. Furthermore, the retention time for achieving the effects of the present invention may be 3 hours or less, preferably 1 hour or less, and more preferably 0.5 hours or less.

[0068] [Road paving method] The asphalt mixture of the present invention is suitable for road paving, and as described above, an asphalt mixture obtained by adding aggregate to an asphalt composition is used for road paving. The road paving method includes a step of applying the asphalt mixture to a road to form an asphalt pavement layer. Specifically, the road paving method includes a step (step 2) of mixing asphalt, the asphalt modifier, and aggregate to obtain an asphalt mixture, and a step (step 3) of applying the asphalt mixture obtained in step 2 to a road to form an asphalt pavement layer. The asphalt pavement layer is preferably a base layer or a surface layer.

[0069] The asphalt mixture may be compacted and applied in the same manner using known construction machinery. From the viewpoint of the durability of the asphalt pavement, the compaction temperature when used as a heated asphalt mixture is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 130°C or higher, and is preferably 200°C or lower, more preferably 180°C or lower. [Example]

[0070] The physical properties of the resin and the like were measured and evaluated by the following methods. [Measurement method] [Acid value and hydroxyl value of polyesteramide] The acid value and hydroxyl value of the polyesteramide 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)).

[0071] [Softening point and glass transition point] (1) Softening point Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C / min, while applying a load of 1.96 MPa with the plunger, and extruded from a nozzle 1 mm in diameter and 1 mm in length. The plunger depression distance of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point. (2) Glass transition temperature Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.01-0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and cooled to 0°C at a rate of 10°C / min. Measurements were then performed while the temperature was increased to 150°C at a rate of 10°C / min. The glass transition temperature was determined as the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex. [Measurement of solubility in toluene] 0.5 g of polyesteramide was placed in a 300 mL or 1000 mL beaker, toluene was added, and the mixture was stirred for 1 hour using a stirrer. After stirring, the solution was allowed to stand for 1 hour and the presence or absence of precipitate was checked. Toluene was added gradually, starting with a small amount, and the above stirring and standing procedure was repeated after each addition. After standing, the solubility was calculated from the amount of toluene added when no precipitate was observed.

[0072] Production Examples 1 to 7 (Polyesteramides A1 to A7) The alcohol component, carboxylic acid component, and polyamide component shown in Table 1 were placed in a 10-L four-neck flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, nitrogen inlet tube, and thermocouple, and tin(II) di(2-ethylhexanoate) was added under a nitrogen atmosphere and the temperature was raised to 235°C. The mixture was then reacted at 235°C for 6 hours, and then further reacted at 235°C and a reduced pressure of 8.3 kPa for 1 hour to obtain polyesteramides A1 to A7. The results are shown in Table 1. For polyesteramide A5, the melting point was measured.

[0073] Manufacturing Example 8 (Polyester a1) The alcohol and carboxylic acid components shown in Table 1 were placed in a 10-L four-neck flask equipped with a thermometer, stainless steel stirring rod, dehydration tube, nitrogen inlet tube, and thermocouple. Under a nitrogen atmosphere, tin(II) di(2-ethylhexanoate) and gallic acid were added, and the temperature was raised to 235°C. The reaction was then continued at 235°C for 8 hours, and then further continued at 235°C and a reduced pressure of 8.3 kPa until the softening point indicated, yielding polyester a1. The results are shown in Table 1.

[0074] [Table 1]

[0075] Example 1 15 kg of aggregate preheated to 180°C (see below for aggregate composition) was placed in an asphalt mixer and mixed at 180°C for 30 seconds. 0.82 kg of modified type II asphalt (manufactured by Toa Road Industry Co., Ltd., "HR Binder") was then added and mixed for 30 seconds. 165 g of polyesteramide A1 obtained in Production Example 1 was then added as a resin and mixed for another 1 minute to obtain asphalt mixture AS-1. The resulting asphalt mixture AS-1 was stored at 180°C for 1 hour, after which approximately 10.7 kg of the asphalt mixture was filled into a metal formwork (300 x 300 x 50 mm) and compacted at 150°C, 0.44 kPa load, and 25 rotations using an air-operated roller compactor (manufactured by Iwata Kogyosho Co., Ltd.) to produce wheel tracking specimen T-1.

[0076] <Aggregate composition> No. 6 crushed stone 38.5 parts by mass No. 7 crushed stone 12.0 parts by mass Crushed sand 10.5 parts by mass Coarse sand 22.0 parts by mass Mountain sand 10.5 parts by mass Stone powder 5.0 parts by mass Fine aggregate powder 1.5 parts by mass Passed mass%: Sieve size 19.0 mm: 100% by mass Sieve size 9.50mm: 80.9% by mass Sieve size 4.75mm: 61.0% by mass Sieve size 2.36mm: 45.0% by mass Sieve size 1.18mm: 30.7% by mass Sieve size 600 μm: 20.5 mass% Sieve size 300 μm: 13.3 mass% Sieve size 150 μm: 9.2 mass%

[0077] Examples 2 to 7 Asphalt mixtures AS-2 to AS-7 were prepared in the same manner as in Example 1 except that the blending ratios shown in Table 2 were used, and wheel tracking specimens T-2 to T-7 were fabricated.

[0078] Comparative Examples 1 to 4 Asphalt mixtures AS-C1 to AS-C4 were prepared in the same manner as in Example 1 except that the blending ratios shown in Table 2 were used, and wheel tracking specimens TC1 to TC4 were fabricated. In Comparative Examples 3 and 4, nylon 6 (manufactured by Unitika Ltd., grade A1030BRL) was used as resin a2.

[0079] [Water resistance evaluation] A water-immersion wheel tracking test was conducted under high-temperature conditions using a water-immersion wheel tracking tester (Iwata Kogyosho Co., Ltd., "AI-1100-S") at a temperature of 60°C, a running speed of 15 strokes per minute, a load of 140 kgf, and steel wheels. The evaluation index was the stripping inflection point (SIP). The definition of SIP in water-immersion wheel tracking tests was based on the following literature. Near the SIP, moisture penetration causes the asphalt composition to peel from the aggregate, and this peeling rapidly accelerates deformation and destruction of the test specimen beyond the SIP. Therefore, the more wheel strokes required to reach the stripping inflection point, the more water-resistant the asphalt pavement is. A stripping inflection point of 500 or more strokes was considered a pass. Literature: AASHTO T 324,2019 Edition,2019-Standard Method of Test for Hamburg Wheel-Track Testing of Compacted Asphalt Mixtures The results are shown in Table 2.

[0080] [Table 2]

[0081] The results in Table 2 show that Examples 1 to 7, which are asphalt mixtures containing specified polyesteramides, have improved water resistance at high temperatures compared to Comparative Example 2, which contains only polyester, Comparative Example 3, which contains only polyamide, and Comparative Example 4, which contains polyester and polyamide separately. Examples 1 and 3, in which the polyamide component of the polyesteramide is nylon 6 or nylon 6,6, have improved water resistance, particularly at high temperatures, compared to Example 6, in which the polyamide component is nylon 12. This is presumably because nylon 6 and nylon 6,6 have dense spacing between amide groups, resulting in more adsorption points for aggregates.

Claims

1. An asphalt composition containing asphalt and an asphalt modifier, wherein the asphalt modifier contains a polyester amide including a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from a polyamide component.

2. The asphalt composition according to Claim 1, wherein in the polyester amide, the molar ratio [alcohol component / amide bond] of the structural unit derived from the alcohol component to the amide bond in the polyamide component is 40 / 60 or more and 95 / 5 or less.

3. The asphalt composition according to Claim 1 or 2, wherein the polyester amide has a solubility in toluene at 20 °C of 10 g / L or more.

4. The asphalt composition according to Claim 1 or 2, wherein the polyamide component contains one or more selected from nylon 6 and nylon 6,6.

5. The asphalt composition according to Claim 1 or 2, wherein the alcohol component contains an alkylene oxide adduct of bisphenol A.

6. The asphalt composition according to Claim 1 or 2, wherein the content of the asphalt modifier is 0.1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the asphalt.

7. An asphalt mixture containing the asphalt composition according to Claim 1 and an aggregate.

8. The asphalt mixture according to Claim 7, wherein the content of the powder component having a particle size of 150 μm or less in the aggregate is 8% by mass or more and 15% by mass or less.

9. An asphalt modifier containing a polyester amide including a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from a polyamide component.

10. The method for producing an asphalt modifier according to claim 9, comprising the following step 1. Step 1: A step of polycondensing an alcohol component, a carboxylic acid component, and a polyamide component to obtain a polyester amide

11. The method for producing an asphalt mixture according to claim 7 or 8, comprising the following step 1 and step 2. Step 1: A step of polycondensing an alcohol component, a carboxylic acid component, and a polyamide component to obtain a polyester amide Step 2: A step of mixing heated aggregate, asphalt, and the polyester amide obtained in step 1

12. A road paving method, comprising a step of constructing the asphalt mixture according to claim 7 or 8 on a road to form an asphalt paving material layer.