Asphalt mixture

Abstract

To provide an asphalt modifier that gives an asphalt pavement having excellent durability and capable of keeping its blackness even after the start of traffic.SOLUTION: The present invention relates to an asphalt mixture containing a polyester resin (A), a compound (B) illustrated below, asphalt, and aggregate, wherein the aggregate contains an asphalt recycled aggregate. The compound (B): an 8C or greater compound having a hydroxyl group or an amino group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an asphalt mixture, an asphalt modifier, a road paving method, and an additive for recycled asphalt mixtures. [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. In addition, the asphalt coating on the asphalt pavement surface peels off over time, causing the resulting whitening and reducing the visibility of the white lines, which 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 method for producing a heat-type paving material that is excellent in preventing peeling between bitumen and aggregate, characterized by adding a specific amount of a composition that is a specific blend of a condensate obtained by reacting a polyalkylene polyamine of a specific structure with a specific fatty acid, and a modified polyolefin resin having a carboxyl group with a specific acid value, in a specific ratio, to the bitumen. Patent Document 3 discloses a heated asphalt additive containing a specific gallic acid amide or the like, which is a heated asphalt composition that can further improve the effect of preventing separation between asphalt and aggregate, and which does not lose this effect even after prolonged heating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 125421 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-2928 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-323695 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology described in Patent Document 1 allows for the production of highly durable asphalt pavements that are resistant to rutting. However, during the construction of asphalt pavements, after compaction using a roller and opening to traffic, external factors such as friction from repeated vehicle traffic, rainwater, and exposure to ultraviolet rays can cause the asphalt coating to peel off, causing the asphalt to change color from its original black to white, damaging the appearance. This problem is particularly pronounced when recycled asphalt aggregate is used. Furthermore, maintaining the black color is desirable not only from the perspective of the surface aesthetics of the pavement's appearance, but also from the perspective of visibility. Although the technology described in Patent Document 2 can prevent peeling, it is thought that it is not very effective in improving durability. Furthermore, it is presumed that sufficient effects cannot be obtained when using recycled aggregate in which asphalt and aggregate are bonded together. The technology described in Patent Document 3 is specialized in preventing peeling and does not have the effect of improving durability.

[0006] The present invention relates to an asphalt mixture, an asphalt modifier, a road paving method, and an additive for recycled asphalt mixtures, for obtaining an asphalt pavement that is excellent in durability and can maintain its black color even after the road is opened to traffic.

[0007] The present invention relates to the following [1] to [4]. [1] A composition comprising a polyester resin (A), the following compound (B), asphalt, and aggregate, The asphalt mixture, wherein the aggregate contains recycled asphalt aggregate. Compound (B): a compound having 8 or more carbon atoms and a hydroxyl group or an amino group [2] An asphalt modifier containing a polyester resin (A) and the following compound (B): Compound (B): a compound having 8 or more carbon atoms and a hydroxyl group or an amino group [3] A road paving method comprising a step of compacting and applying the asphalt mixture described in [1] above, A road paving method in which the compaction temperature of the asphalt mixture is 100°C or higher and 200°C or lower. [4] An additive for recycled asphalt mixtures containing one or more compounds having 8 or more carbon atoms selected from alkylamines, alkyl alcohols, sugar alcohols, and alkylamide compounds. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an asphalt mixture, an asphalt modifier, a road paving method, and an additive for recycled asphalt mixtures for obtaining asphalt pavement that is excellent in durability and can maintain its black color even after the road is opened to traffic. DETAILED DESCRIPTION OF THE INVENTION

[0009] The asphalt mixture of the present invention contains asphalt and aggregates including recycled aggregate, and asphalt modifiers, polyester resin (A) and compound (B), which is a compound having hydroxyl groups or amino groups and 8 or more carbon atoms. The asphalt modifiers can be used alone or in combination of two or more. Below, we will explain the asphalt modifier contained in the asphalt mixture and its manufacturing method, the asphalt composition and its manufacturing method, the asphalt mixture and its manufacturing method, the road paving method, and the additive for recycled asphalt mixtures in that order.

[0010] [Asphalt modifier] The asphalt modifier of the present invention contains a polyester resin (A) and the following compound (B). Compound (B): a compound having 8 or more carbon atoms and a hydroxyl group or an amino group The present inventors have discovered that by incorporating an asphalt modifier that combines a polyester resin (A) and a specified compound (B) into an asphalt composition or asphalt mixture, it is possible to obtain an asphalt pavement that is excellent in durability and that can maintain its black color even after the pavement is opened to traffic. The amino group referred to here includes a primary amino group (-NH), a secondary amino group (-NRH), and a tertiary amino group (-NRR'). The amino group also includes -NH- and -NR- in an amide bond (-NH-CO- or -NR-CO-).

[0011] Although the detailed mechanism by which the effects of the present invention are obtained is unknown, part of it is thought to be as follows. It is believed that the asphalt modifier, which uses a highly compatible polyester resin (A) in combination with a specific compound (B), improves the coating state of the binder composition on the aggregate. When recycled asphalt aggregate is used as aggregate, the asphalt in the recycled asphalt aggregate deteriorates due to its thermal history over time, and asphalt may not be extracted efficiently. In the present invention, by using a specific compound (B) that has a high affinity with recycled asphalt aggregate in combination, it is believed that the asphalt in the recycled asphalt aggregate can be efficiently extracted, and a good coating state of the aggregate can be achieved, even when recycled aggregate is used as aggregate. Specifically, it is believed that the carbon atoms of compound (B) have a high affinity with the asphalt in the recycled asphalt aggregate, and that the hydroxyl or amino groups of compound (B) have a high affinity with the surface of aggregate that is not covered with asphalt. Due to these affinities, compound (B) acts at the interface between the asphalt and aggregate in the recycled asphalt aggregate, promoting the asphalt in the recycled aggregate to peel from the aggregate and dissolve into the newly mixed asphalt. This, combined with polyester resin (A), functions as a binder, achieving a good coating state on the aggregate. Furthermore, it is believed that the good coating state on the aggregate firmly holds the aggregate in the pavement, thereby maintaining the durability and black color of the pavement. As described above, by incorporating the asphalt modifier of the present invention into an asphalt composition or asphalt mixture, it is believed that an asphalt pavement that is excellent in durability and can maintain its black color even after traffic is opened can be obtained, especially when recycled asphalt aggregate is included.

[0012] The definitions of various terms used in this specification are shown below. In the polyester resin, a "structural unit derived from an alcohol component" means a structure in which a hydrogen atom is removed from a hydroxyl group (hydroxy group) of an alcohol component, and a "structural unit derived from a carboxylic acid component" means a structure in which a hydroxyl group is removed from a carboxyl 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. Whether a resin is crystalline or amorphous is determined by its crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the temperature of the maximum endothermic peak (softening point (°C) / maximum endothermic peak temperature (°C)). A crystalline resin is one with a crystallinity index of 0.3 or more and 1.4 or less. An amorphous resin is one in which no endothermic peak is observed, or if an endothermic peak is observed, the crystallinity index is less than 0.3 or more than 1.4. The crystallinity index can be adjusted appropriately by adjusting the types and ratios of raw material monomers, as well as production conditions such as reaction temperature, reaction time, and cooling rate.

[0013] [Polyester resin (A)] The asphalt modifier of the present invention contains a polyester resin (A). The polyester resin (A) contains structural units derived from an alcohol component and structural units derived from a carboxylic acid component. The polyester resin (A) may be an amorphous polyester resin or a crystalline polyester resin, and is preferably an amorphous polyester resin. The alcohol component, the carboxylic acid component, and the physical properties of the polyester resin will be described below.

[0014] <Alcohol content> Examples of the alcohol component include aliphatic diols, alicyclic diols, aromatic diols, trihydric or higher polyhydric alcohols, etc. These alcohol components can be used alone or in combination of two or more.

[0015] The aliphatic diol is preferably a linear or branched aliphatic diol having 2 to 12 carbon atoms in the main chain, more preferably a linear or branched aliphatic diol having 2 to 8 carbon atoms in the main chain. The aliphatic diol is preferably a saturated aliphatic diol. Specific examples of aliphatic diols 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.

[0016] Examples of alicyclic diols include hydrogenated bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane), alkylene oxide adducts of hydrogenated bisphenol A, cyclohexanediol, and cyclohexanedimethanol.

[0017] Examples of aromatic diols include bisphenol A [2,2-bis(4-hydroxyphenyl)propane] and alkylene oxide adducts of bisphenol A. Examples of alkylene oxide adducts of bisphenol A include alkylene oxide adducts of bisphenol A represented by the following formula (I):

[0018] [ka]

[0019] [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.

[0020] Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A. These alkylene oxide adducts of bisphenol A can be used alone or in combination of two or more.

[0021] The trihydric or higher polyhydric alcohol is preferably a trihydric alcohol, and examples of the trihydric or higher polyhydric alcohol include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0022] 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.

[0023] <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.

[0024] 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.

[0025] Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, or anhydrides thereof, and alkyl esters thereof (for example, alkyl groups having 1 to 3 carbon atoms). Of the above aromatic dicarboxylic acids, isophthalic acid and terephthalic acid are preferred, with terephthalic acid being more preferred, from the viewpoint of durability of asphalt pavement.

[0026] 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.

[0027] 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.

[0028] <Structural units derived from polyethylene terephthalate> The polyester resin (A) may contain ethylene glycol-derived structural units and terephthalic acid-derived structural units derived from polyethylene terephthalate. The polyethylene terephthalate may contain small amounts of components such as butanediol and isophthalic acid in addition to the ethylene glycol-derived and terephthalic acid-derived structural units. The polyethylene terephthalate is preferably recycled polyethylene terephthalate. When the polyester resin (A) contains structural units consisting of ethylene glycol and terephthalic acid derived from polyethylene terephthalate, the "structural units derived from an alcohol component" include structural units derived from ethylene glycol derived from polyethylene terephthalate, and the "structural units derived from a carboxylic acid component" include structural units derived from terephthalic acid derived from polyethylene terephthalate.

[0029] <Molar ratio of structural units derived from carboxylic acid component to structural units derived from alcohol component> The molar ratio of structural units derived from carboxylic acid components to structural units derived from alcohol components [carboxylic acid component / alcohol component] is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and is preferably 1.5 or less, more preferably 1.3 or less, even more preferably 1.0 or less.

[0030] In one preferred embodiment of the present invention, the polyester resin (A) contains a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component, the alcohol component is at least one selected from aliphatic diols, alicyclic diols, aromatic diols, and trihydric or higher polyhydric alcohols; The carboxylic acid component is at least one selected from aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and polycarboxylic acids having a valence of 3 or more and 6 or less.

[0031] <Physical properties of polyester resin (A)> From the viewpoint of durability of the asphalt pavement, the softening point or melting point of the polyester resin (A) is preferably 60°C or higher, more preferably 70°C or higher, even more preferably 90°C or higher, even more preferably 100°C or higher, and preferably 150°C or lower, more preferably 145°C or lower, even more preferably 140°C or lower. The melting point (the temperature of the maximum endothermic peak) is generally observed when the polyester resin (A) is a crystalline polyester resin. The softening point of the polyester resin (A) can be measured by the method described in the Examples. The softening point can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0032] The polyester resin (A) may be a polyester resin modified to such an extent that its properties are not substantially impaired. Specific examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like, by methods described in JP-A Nos. 11-133668, 10-239903, and 8-20636. A preferred modified polyester resin is a urethane-modified polyester resin obtained by urethane-extending a polyester resin with a polyisocyanate compound.

[0033] <Method for producing polyester resin (A)> The method for producing the polyester resin (A) constituting the asphalt modifier of the present invention is not particularly limited, but it can be produced, for example, by polycondensing the alcohol component and carboxylic acid component described above. The amounts of the alcohol component and the carboxylic acid to be blended are such that the molar ratio of the structural units derived from the carboxylic acid component to the structural units derived from the alcohol component [carboxylic acid component / alcohol component] falls within the above-mentioned 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, even more preferably 190°C or higher, and preferably 260°C or lower, more preferably 250°C or lower, even more preferably 240°C or lower.

[0034] When the polyester resin used in the present invention contains structural units derived from ethylene glycol derived from polyethylene terephthalate and structural units derived from terephthalic acid derived from polyethylene terephthalate, the amount of polyethylene terephthalate present in the raw material is preferably 5% by mass or more, more preferably 15% by mass or more, even more preferably 25% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, even more preferably 60% by mass or less, of the total amount of polyethylene terephthalate, alcohol component, and carboxylic acid component. By adding polyethylene terephthalate during the polycondensation reaction between the alcohol component and the carboxylic acid component, an ester exchange reaction occurs, and a polyester resin can be obtained in which the structural units of polyethylene terephthalate are incorporated into structural units derived from the alcohol component and structural units derived from the carboxylic acid component. Polyethylene terephthalate may be present from the start of the polycondensation reaction, or may be added to the reaction system during the polycondensation reaction. From the viewpoint of the durability of the asphalt pavement, the timing of adding polyethylene terephthalate is preferably when the reaction rate between the alcohol component and the carboxylic acid component is 10% or less, and more preferably when it is 5% or less. The reaction rate refers to the value of the amount of water produced by reaction (moles) / the theoretical amount of water produced (moles) × 100.

[0035] In view of the reaction rate, an esterification catalyst can be used in the polycondensation reaction. Examples of the esterification catalyst include tin(II) compounds that do not have a Sn-C bond, such as tin(II) di(2-ethylhexanoate). From the viewpoint of the 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, and even more preferably 0.2 parts by mass or more, relative to 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component, and is 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. In addition to the esterification catalyst, a co-catalyst can be used in the polycondensation reaction. Examples of the co-catalyst include pyrogallol compounds such as gallic acid. The amount of the co-catalyst used is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, and 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, per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component. In addition to the catalyst, a polymerization inhibitor such as tertiary butyl catechol may be used in the polycondensation reaction in an amount of 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, and even more preferably 0.1 part by mass or less, per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0036] <Compound (B)> From the viewpoint of maintaining the black color of the asphalt pavement, the asphalt composition of the present invention contains (B) a compound having 8 or more carbon atoms and having a hydroxyl group (hydroxy group) or an amino group, preferably one or more compounds having 8 or more carbon atoms selected from alkylamines, alkyl alcohols, sugar alcohols, and alkylamides. As compound (B), one compound may be used alone, or two or more compounds may be used in combination. The compound (B) has 8 or more carbon atoms, preferably 10 or more, more preferably 12 or more, and preferably 30 or less, more preferably 25 or less, and even more preferably 20 or less. From the viewpoint of affinity with the asphalt in the recycled asphalt aggregate, compound (B) preferably has an alkyl or alkenyl group having 8 or more carbon atoms, more preferably has an alkyl group having 8 or more carbon atoms, and even more preferably has a straight-chain alkyl group having 8 or more carbon atoms. The number of carbon atoms in the alkyl or alkenyl group is more preferably 10 or more, even more preferably 12 or more, and is preferably 30 or less, more preferably 25 or less, even more preferably 20 or less.

[0037] [Alkylamines with 8 or more carbon atoms] The alkylamine having 8 or more carbon atoms has one or more amino groups and alkyl groups, and there are no limitations on its structure as long as the total number of carbon atoms is 8 or more. The number of amino groups that the alkylamine has is not particularly limited, and from the viewpoint of maintaining the black color of the asphalt pavement, it is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Furthermore, the amino group possessed by the alkylamine may be any of a primary amino group, a secondary amino group, or a tertiary amino group, and from the viewpoint of maintaining the black color of the asphalt pavement, a primary amino group or a secondary amino group is preferred, and a primary amino group is more preferred. When an alkylamine has two amino groups, for example, it has one primary amino group and one secondary amino group in the molecule. Specific examples of alkylamines include primary amines such as octylamine, decylamine, laurylamine, myristylamine, palmitylamine, stearylamine, oleylamine, coconut amine, soy amine, tallow amine, and hardened tallow amine; Secondary amines such as dibutylamine, dioctylamine, didecylamine, dilaurylamine, dimyristylamine, dipalmitylamine, distearylamine, dioleylamine, dicoconutamine, disoyaamine, ditallowamine, and di-hardened tallowamine; Tertiary amines such as dimethyloctylamine, dimethyldecylamine, dimethyllaurylamine, dimethylmyristylamine, dimethylpalmitylamine, dimethylstearylamine, dimethyloleylamine, dimethylcoconutamine, dimethylsoyamine, dimethyl tallowamine, and dimethyl hardened tallowamine; Diamines such as octyl propylene diamine, decyl propylene diamine, lauryl propylene diamine, myristyl propylene diamine, palmityl propylene diamine, stearyl propylene diamine, oleyl propylene diamine, coconut propylene diamine, soy propylene diamine, tallow propylene diamine, and hardened tallow propylene diamine; Examples of the alkylamine include triamines such as beef tallow dipropylene triamine, etc. These alkylamines can be used alone or in combination of two or more. As the alkylamine, preferred are tallow amine, tallow triamine and dimethyldecylamine, more preferred are tallow amine.

[0038] It should be noted that coconut amine, soy amine, tallow amine, hydrogenated tallow amine, dicoconat amine, disoyamine, ditallow amine, dihydrogenated tallow amine, dimethyl coconut amine, dimethyl soy amine, dimethyl tallow amine, dimethyl hydrogenated tallow amine, coconut propylene diamine, soy propylene diamine, tallow propylene diamine, hydrogenated tallow propylene diamine, and tallow dipropylene triamine are mixed amines containing two or more alkylamines.

[0039] Commercially available alkylamines include "DANOX AP," "ASFIER N480L," "Farmin 86T," "Farmin D86," "Farmin DM20," "Triamine T," and "Triamine R-86" (all trade names, manufactured by Kao Corporation), "Armin 16D," "Armin 2C," and "Armin DMSD" (all trade names, manufactured by Lion Corporation), etc.

[0040] [Alkyl alcohol with 8 or more carbon atoms] The alkyl alcohol having 8 or more carbon atoms has one or more hydroxyl groups and an alkyl group, and there are no limitations on its structure as long as the total number of carbon atoms is 8 or more. The number of hydroxy groups that the alkyl alcohol has is not particularly limited, and from the viewpoint of maintaining the black color of the asphalt pavement, it is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Furthermore, the hydroxyl group possessed by the alkyl alcohol may be a primary hydroxyl group, a secondary hydroxyl group, or a tertiary hydroxyl group, and from the viewpoint of maintaining the black color of the asphalt pavement, a primary hydroxyl group or a secondary hydroxyl group is preferred, and a primary hydroxyl group is more preferred.

[0041] Specific examples of alkyl alcohols include octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, etc. These alkyl amines can be used alone or in combination of two or more. The alkyl alcohol is preferably lauryl alcohol. Commercially available alkyl alcohols include "Kalcol 8098" and "Kalcol 2098" (all trade names, manufactured by Kao Corporation), which contain one type of alkyl alcohol, and "Kalcol 8650," "Kalcol 4250," "Rheodol SP-S30V," and "Rheodol SP-O30V" (all trade names, manufactured by Kao Corporation), which contain two or more types of alkyl alcohols.

[0042] [Sugar alcohols with 8 or more carbon atoms] The sugar alcohol having 8 or more carbon atoms has one or more hydroxyl groups and a sugar alcohol skeleton portion, and there are no restrictions on its structure as long as the total number of carbon atoms is 8 or more. Preferably, it is an ester of a sugar alcohol and a fatty acid. Examples of the sugar alcohol skeleton include glycerol, sorbitol, sorbitan, etc. Examples of fatty acids that constitute the ester include oleic acid, palmitic acid, stearic acid, etc. The number of hydroxyl groups that the sugar alcohol has is not particularly limited, and from the viewpoint of maintaining the black color of the asphalt pavement, it is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Furthermore, the hydroxyl group possessed by the sugar alcohol may be a primary hydroxyl group, a secondary hydroxyl group, or a tertiary hydroxyl group, and from the viewpoint of maintaining the black color of the asphalt pavement, a primary hydroxyl group or a secondary hydroxyl group is preferred, and a primary hydroxyl group is more preferred.

[0043] Specific examples of sugar alcohols include sugar alcohols having two hydroxyl groups, such as glycerol monostearate, glycerol monooleate, sorbitan distearate, and sorbitan diolate, and sugar alcohols having three hydroxyl groups, such as sorbitan monolaurate, sorbitan monopalmitate, and sorbitan monostearate. These sugar alcohols can be used alone or in combination of two or more. The sugar alcohol is preferably sorbitan monostearate. Commercially available sugar alcohols include "Rheodol MS-50," "Rheodol MO-60," "Rheodol SP-S20," "Rheodol SP-L10," and "Rheodol SP-S10V" (all trade names, manufactured by Kao Corporation).

[0044] [Alkylamide with 8 or more carbon atoms] Alkylamides having 8 or more carbon atoms have an amide group and an alkyl group, and there are no limitations on their structure as long as the total number of carbon atoms is 8 or more. Alkylamides also include alkylalkanolamides.

[0045] Specific examples of alkylamides include ethylene bisstearamide, stearamide, oleamide, etc. Specific examples of alkylalkanolamides include stearylethanolamide, laurylethanolamide, etc. These alkylamides can be used alone or in combination of two or more. The alkylamide is preferably ethylene bisstearamide. Commercially available alkylamide products include "Kaowax EB-G," "Fatty Acid Amide T," "Fatty Acid Amide S," "Aminone L-02," and "Aminone PK-02S" (all trade names, manufactured by Kao Corporation).

[0046] Among these, the compound (B) is preferably an alkylamine, an alkyl alcohol, or a sugar alcohol, more preferably an alkylamine.

[0047] <Contents of Polyester Resin (A) and Compound (B)> In the asphalt modifier, the mass ratio of polyester resin (A) to compound (B) [polyester resin (A) / compound (B)] is preferably 4 or more, more preferably 5 or more, even more preferably 6 or more, from the viewpoint of the durability of the asphalt pavement and maintaining the black color of the asphalt pavement, and is preferably 39 or less, more preferably 30 or less, even more preferably 25 or less.

[0048] The asphalt modifier of the present invention may contain components other than the polyester resin (A) and the compound (B) to the extent that the effects are not impaired, or may consist only of the polyester resin (A) and the compound (B). The total content of the polyester resin (A) and the compound (B) in the asphalt modifier is preferably 50 mass % or more, more preferably 70 mass % or more, and even more preferably 85 mass % or more, based on the total mass of the asphalt modifier.

[0049] The asphalt modifier of the present invention can be used, for example, by mixing it 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 an asphalt modifier to be blended into asphalt mixtures containing aggregate.

[0050] [Asphalt composition] The asphalt composition of the present invention contains the polyester resin (A), the compound (B), and asphalt.

[0051] <Asphalt> Various types of asphalt can be used. Examples include straight asphalt, which is petroleum asphalt for paving, as well as modified asphalt. Modified asphalts include blown asphalt and polymer-modified asphalt modified with polymeric materials such as thermoplastic elastomers and thermoplastic resins. Straight asphalt refers to the residual bitumen 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 oxidizing it by blowing air into it. The asphalt is preferably selected from straight asphalt and polymer-modified asphalt, with polymer-modified asphalt being more preferred from the viewpoint of the durability of the asphalt pavement and straight asphalt being more preferred from the viewpoint of versatility. As polymer-modified asphalt, asphalt modified with a thermoplastic elastomer is more preferred.

[0052] (thermoplastic elastomer) Examples of the thermoplastic elastomer in asphalt modified with a thermoplastic elastomer include at least one selected from styrene / butadiene block copolymers, styrene / butadiene / styrene block copolymers, styrene / butadiene random copolymers, styrene / isoprene block copolymers, styrene / isoprene / styrene block copolymers, styrene / isoprene random copolymers, ethylene / vinyl acetate copolymers, ethylene / acrylate 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 natural rubber.

[0053] Among these, from the viewpoint of durability of asphalt pavement, the thermoplastic elastomer is preferably at least one selected from styrene / butadiene block copolymer, styrene / butadiene / styrene block copolymer, styrene / butadiene random copolymer, styrene / isoprene block copolymer, styrene / isoprene / styrene block copolymer, styrene / isoprene random copolymer, and ethylene / acrylic acid ester copolymer, more preferably at least one selected from styrene / butadiene block copolymer, styrene / butadiene / styrene block copolymer, styrene / butadiene random copolymer, styrene / isoprene block copolymer, and styrene / isoprene random copolymer, and even more preferably at least one selected from styrene / butadiene random copolymer and styrene / butadiene / styrene block copolymer. 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.

[0054] <Contents of Polyester Resin (A) and Compound (B)> In the asphalt composition of the present invention, the total content of the polyester resin (A) and the compound (B) is, from the viewpoint of the durability of the asphalt pavement and maintaining the black color of the asphalt pavement, preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, per 100 parts by mass of asphalt, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less.

[0055] 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.

[0056] [Method for producing asphalt composition] The method for producing the asphalt composition of the present invention preferably includes a step of mixing asphalt with the polyester resin (A) and the compound (B).

[0057] The asphalt composition can be obtained by heating and melting asphalt, adding the polyester resin (A) and the compound (B), and stirring and mixing the components until they are uniformly dispersed using a commonly used mixer. Commonly used mixers include homomixers, dissolvers, paddle mixers, ribbon mixers, screw mixers, planetary mixers, vacuum countercurrent mixers, roll mills, and twin-screw extruders.

[0058] From the viewpoint of uniformly dispersing the polyester resin (A) and the compound (B) in the asphalt, the mixing temperature of the asphalt with the polyester resin (A) and the compound (B) is preferably 100°C or higher, more preferably 130°C or higher, even more preferably 160°C or higher, still more preferably 170°C or higher, and is preferably 230°C or lower, more preferably 210°C or lower, even more preferably 200°C or lower, and still more preferably 190°C or lower.

[0059] Furthermore, from the viewpoint of efficiently dispersing the polyester resin (A) and the compound (B) uniformly in the asphalt, the mixing time of the asphalt with the polyester resin (A) and the compound (B) is preferably 0.1 hour or longer, more preferably 0.5 hour or longer, even more preferably 1.0 hour or longer, still more preferably 1.5 hour or longer, and is preferably 10 hours or shorter, more preferably 7 hours or shorter, even more preferably 5 hours or shorter, and still more preferably 3 hours or shorter.

[0060] [Asphalt mixture] The asphalt mixture of the present invention contains the polyester resin (A), the compound (B), asphalt, and aggregate, and the aggregate contains recycled asphalt aggregate.

[0061] The total content of the polyester resin (A) and the compound (B) 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 is 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.

[0062] In the asphalt mixture of the present invention, the total content of the polyester resin (A) and the compound (B) is, from the viewpoint of the durability of the asphalt pavement and maintaining the black color of the asphalt pavement, preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, per 100 parts by mass of asphalt, and is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less. The asphalt content in the asphalt mixture is the total content of new asphalt and asphalt derived from recycled asphalt aggregate. The asphalt content in an asphalt mixture can be determined from the blending amount. It can also be determined by measuring the loss on ignition using an asphalt mixture or asphalt pavement. Loss on ignition measurement is performed according to the method specified in AASHTO (American Association of State Highway and Transportation Officials) T 308-10 (2015). Since recycled aggregate, described below, is included as an aggregate, the amount of asphalt is determined from the loss on ignition of the recycled asphalt aggregate and used in the blending calculation.

[0063] <Aggregate> The aggregate essentially contains recycled asphalt aggregate, and other materials such as crushed stone, boulders, gravel, sand, and ceramics can also be selected and used as desired. As for the aggregate, 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 can be used. 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.

[0064] 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 powder such as limestone powder, and slaked lime. Among these, calcium carbonate powder 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.

[0065] 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.

[0066] The aggregate includes recycled asphalt aggregate. Recycled asphalt aggregate is made by collecting used asphalt pavement, crushing it, and classifying it. The post-consumer asphalt pavement from which the recycled asphalt aggregate is derived contains asphalt and aggregate, and may contain other additives as needed. The physical and chemical properties of the asphalt contained in recycled asphalt aggregate have deteriorated due to the effects of environmental factors such as heat and light. The physical and chemical properties of asphalt can be evaluated by measuring the asphalt's penetration, softening point, flexural strength, strain at break, asphalt composition, etc. Generally, asphalt in which the maltene fraction in asphalt has migrated to asphaltene and the penetration has decreased is often referred to as deteriorated asphalt. However, even if the penetration of recycled asphalt is equivalent to that of new asphalt, changes in other properties may prevent it from exhibiting the same performance as new asphalt.

[0067] The aggregate content in the asphalt mixture is preferably 90% by mass or more, more preferably 92% by mass or more, even more preferably 93% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, even more preferably 96% by mass or less. The content of recycled asphalt aggregate in the asphalt mixture is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of reducing the environmental impact and reducing production costs, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, from the viewpoint of ensuring quality stability and workability.

[0068] 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.

[0069] [Asphalt mixture manufacturing method] The asphalt mixture of the present invention can be obtained, for example, by a production method including a step of adding and mixing a mixture of pre-heated and mixed asphalt, polyester resin (A), and the compound (B) to heated aggregate. Specific methods for producing asphalt mixtures include conventional methods for producing asphalt mixtures known as the plant mix method and the premix method. Both methods involve adding polyester resin (A) and compound (B) to heated aggregate, asphalt (and thermoplastic elastomer, if necessary). Examples of the addition method include the premix method, in which asphalt (and thermoplastic elastomer, if necessary), polyester resin (A), and compound (B) are dissolved in advance, or the plant mix method, in which modified asphalt in which thermoplastic elastomer is dissolved in asphalt is added to aggregate, and then polyester resin (A) and compound (B) are added. Among these, the premix method is preferred from the viewpoint of exerting asphalt performance. More specifically, in the method for producing an asphalt mixture, preferably, in the mixing step, (i) Adding and mixing asphalt (and thermoplastic elastomer, if necessary) to heated aggregate to obtain a mixture, then adding polyester resin (A) and compound (B) and mixing the mixture with the polyester resin; (ii) Adding and mixing the asphalt (and optionally the thermoplastic elastomer), the polyester resin (A) and the compound (B) simultaneously to the heated aggregate, or (iii) A mixture of asphalt (and thermoplastic elastomer, if necessary), polyester resin (A) and compound (B) that has been pre-heat mixed is added to the heated aggregate and mixed. Among these, method (iii) is preferred from the viewpoint of exerting asphalt performance.

[0070] The temperature when asphalt, polyester resin (A) and compound (B) are mixed with heated aggregate is preferably 130°C or higher, more preferably 140°C or higher, from the viewpoint of softening the asphalt and exhibiting asphalt performance, and is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C or lower. Furthermore, the time for mixing the heated aggregate with the asphalt, polyester resin (A) and compound (B) is preferably 30 seconds or more, more preferably 1 minute or more, even more preferably 2 minutes or more, and even more preferably 5 minutes or more, from the viewpoint of exhibiting asphalt performance, and the upper limit of the time is not particularly limited, but is, for example, about 30 minutes.

[0071] In the above method (iii), the method for preparing a mixture of preheated and mixed asphalt (and thermoplastic elastomer, if necessary), polyester resin (A), and compound (B) is not particularly limited, but it preferably includes a step of heating and melting the asphalt, adding the polyester resin (A), compound (B), and other additives if necessary, and stirring and mixing the components in a commonly used mixer until they are uniformly dispersed. Commonly used mixers include homomixers, dissolvers, paddle mixers, ribbon mixers, screw mixers, planetary mixers, vacuum countercurrent mixers, roll mills, twin-screw extruders, etc.

[0072] The mixing temperature of the asphalt, polyester resin (A) and compound (B) is preferably 100°C or higher, more preferably 130°C or higher, even more preferably 160°C or higher, and even more preferably 170°C or higher, from the viewpoint of uniformly dispersing the polyester resin in the asphalt and exhibiting asphalt performance, and is preferably 230°C or lower, more preferably 210°C or lower, even more preferably 200°C or lower, and even more preferably 190°C or lower.

[0073] Furthermore, the mixing time for the asphalt, polyester resin (A) and compound (B) is preferably 0.1 hour or longer, more preferably 0.5 hour or longer, even more preferably 1.0 hour or longer, and even more preferably 1.5 hour or longer, from the viewpoint of efficiently dispersing the polyester resin (A) and compound (B) uniformly in the asphalt and exhibiting asphalt performance, and is preferably 10 hours or shorter, more preferably 7 hours or shorter, even more preferably 5 hours or shorter, and even more preferably 3 hours or shorter. The preferred contents of the polyester resin (A) and the compound (B) relative to the asphalt are as described above.

[0074] In the above method (iii), the mixture of asphalt, polyester resin (A) and compound (B) may be used as a hot asphalt mixture substantially free of water, or the asphalt mixture may be blended with an emulsifier and water to form an asphalt emulsion, which may then be blended with aggregate and the like to be used as a cold asphalt mixture. From the viewpoint of exhibiting asphalt performance, the mixture of asphalt and polyester resin preferably does not substantially contain water.

[0075] When the asphalt mixture is used as a heated asphalt mixture, there are no particular limitations on the method for producing the asphalt mixture, and the asphalt mixture may be produced by any method. However, the asphalt mixture may generally be produced in accordance with the method for producing an asphalt mixture containing aggregate and an asphalt composition.

[0076] [Road paving construction method] The asphalt mixture of the present invention is suitable for road pavement. The road pavement construction method of the present invention preferably includes a step of applying the asphalt mixture of the present invention to a road or the like to form an asphalt pavement layer. The asphalt pavement formed from the asphalt mixture of the present invention has excellent aggregate scattering suppression and water resistance, and can be suitably used in drainage pavements.

[0077] The road pavement construction method of the present invention preferably includes a step of applying the asphalt mixture of the present invention to the surface course of a road. In particular, it is preferable to apply the asphalt mixture of the present invention to the surface course of an expressway.

[0078] In road paving methods, the asphalt mixture can be compacted and applied using the same construction machinery and methods as for ordinary asphalt mixtures. To ensure optimal asphalt performance, the compaction temperature of the asphalt mixture 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, and even more preferably 170°C or lower. That is, one preferred embodiment of the road paving method of the present invention is a road paving method that includes a step of compacting and applying the asphalt mixture, in which the compaction temperature of the asphalt mixture is 100°C or higher and 200°C or lower.

[0079] [Additive for recycled asphalt mixtures] As will be shown in the Examples below, compound (B) alone is effective in maintaining the black color of asphalt pavement even after traffic is reopened. Therefore, the present invention also provides an additive for recycled asphalt mixtures containing a compound having 8 or more carbon atoms and a hydroxyl group or an amino group, preferably one or more compounds having 8 or more carbon atoms selected from alkylamines, alkyl alcohols, sugar alcohols, and alkylamide compounds. From the viewpoint of maintaining the black color of the asphalt pavement, the amount of compound (B) used is preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1.0 part by mass or more, per 100 parts by mass of asphalt, and is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 2.0 parts by mass or less. The additive of the present invention is used as an additive when producing a recycled asphalt mixture containing recycled asphalt aggregate as the aggregate. [Example]

[0080] The physical properties of the resin and the like were measured and evaluated by the following methods. [Measurement method] (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.

[0081] Production Example 1 (Polyester Resin A1) The alcohol component and terephthalic acid, among the raw material monomers shown in Table 1, were placed in a 10-L four-neck flask equipped with a thermometer, a stainless steel stirrer, a dehydration tube, a downflow condenser, and a nitrogen inlet tube. The amounts of tin(II) di(2-ethylhexanoate) and gallic acid shown in Table 1 were added under a nitrogen atmosphere. The mixture was heated to 235°C over 3 hours in a mantle heater, held at 235°C for 5 hours, and then reacted under reduced pressure at 8.0 kPa for 1 hour. After cooling to 180°C, alkenylsuccinic anhydride was added. The mixture was heated to 210°C over 2 hours, held at 210°C for 1 hour, and then reacted under reduced pressure at 8.3 kPa. The reaction was continued until the softening point shown in Table 1 was reached, yielding Polyester Resin A1.

[0082] Production Example 2 (Polyester Resin A2) The raw material monomers shown in Table 1, alcohol component, terephthalic acid, and PET (polyethylene terephthalate), were placed in a 10-L four-neck flask equipped with a thermometer, stainless steel stirrer, dehydration tube, downflow condenser, and nitrogen inlet tube. The amount of tin(II) di(2-ethylhexanoate) shown in Table 1 was added under a nitrogen atmosphere. The mixture was heated to 235°C over 3 hours in a mantle heater, held at 235°C for 5 hours, and then reacted under reduced pressure at 8.0 kPa for 1 hour. After visually confirming the disappearance of PET particles from the reaction mixture, the mixture was cooled to 180°C and alkenylsuccinic anhydride was added. The mixture was heated to 210°C over 2 hours, held at 210°C for 1 hour, and reacted under reduced pressure at 8.3 kPa. The reaction was continued until the softening point shown in Table 1 was reached, yielding Polyester Resin A2.

[0083] Production Example 3 (Polyester Resin A3) The raw material monomers shown in Table 1 were placed in a 10 L four-neck flask equipped with a thermometer, a stainless steel stirring rod, a dehydration tube, a nitrogen inlet tube, and a thermocouple, and tin(II) di(2-ethylhexanoate) and gallic acid were added. The mixture was maintained at 180°C for 2 hours under a nitrogen atmosphere, and then heated to 210°C over 3 hours. The mixture was then reacted at 210°C for 4 hours, and then reacted under reduced pressure of 8.3 kPa for 1 hour to obtain polyester resin A3.

[0084] Production Example 4 (Polyester Resin A4) The raw material monomers shown in Table 1 were placed in a 10 L four-neck flask equipped with a thermometer, a stainless steel stirring rod, a dehydration tube, a nitrogen inlet tube, and a thermocouple, and held at 140°C for 6 hours under a nitrogen atmosphere. The temperature was then raised to 200°C over a period of 6 hours, after which tin(II) di(2-ethylhexanoate) and gallic acid were added and reacted at 200°C for 1 hour, followed by a reduced pressure reaction at 8.3 kPa for 1 hour to obtain polyester resin A4.

[0085] [Table 1]

[0086] Example 1 12 kg of aggregate (mixture A; see below for aggregate composition) heated to 180°C was placed in an asphalt mixer and mixed at 180°C for 60 seconds. 540 g of straight asphalt (Idemitsu Kosan Co., Ltd.) was then added and mixed for 1 minute in the asphalt mixer. 146 g of polyester resin A1 and 7.7 g of compound B1 (DANOX AP; beef tallow amine mixture, Kao Corporation) were then added and mixed for 2 minutes in the asphalt mixer to obtain asphalt mixture M-1. "DANOX AP" is a mixture of various amines and amidated products (main component: tallow amine) obtained as residue from the tallow amine refining process. (1) Preparation of asphalt specimen T1 for wheel tracking test The resulting asphalt mixture M-1 was quickly filled into a 300 x 300 x 50 mm formwork, and after heat curing at 180°C for 2 hours, it was subjected to a pressure treatment of 25 revolutions at a temperature of 150°C and a load of 0.44 kPa using a roller compactor (manufactured by Iwata Kogyosho Co., Ltd.) to prepare asphalt specimen T1-1.

[0087] (2) Preparation of asphalt specimen T2 for Marshall stability test 1.2 kg of the resulting asphalt mixture M-1 was weighed out and stored at 180°C for 2 hours for thermal curing. After that, it was compacted using a Marshall test compactor, the "Automatic Asphalt Compaction Device" (manufactured by Nakajima Gihan Co., Ltd.), 50 times on each side for a total of 100 times, to produce cylindrical asphalt specimen T2-1 for the Marshall stability test.

[0088] The asphalt mixture contains asphalt derived from newly mixed straight asphalt and asphalt derived from recycled asphalt aggregate. The content of polyester resin A1 in the asphalt mixture was 19 parts by mass, and the content of compound B1 was 1 part by mass, relative to 100 parts by mass of the total content of asphalt.

[0089] <Aggregate composition> [Formulation A] No. 6 crushed stone 31.0 parts by mass Crushed sand 6.0 parts by mass River sand 13.0 parts by mass Mountain sand 6.0 parts by mass Stone powder (calcium carbonate powder) 4.0 parts by mass Recycled asphalt aggregate: 40.0 parts by mass (asphalt content: 4.7% by mass (estimated value)) Passed mass%: Sieve size 15 mm: 100% by mass Sieve size 10 mm: 87.9% by mass Sieve size 5 mm: 57.5% by mass Sieve size 2.5 mm: 53.1% by mass Sieve size 1.2 mm: 36.7% by mass Sieve size 0.6 mm: 23.1% by mass Sieve size 0.3 mm: 12.7% by mass Sieve size 0.15mm: 6.5% by mass

[0090] The asphalt content in the recycled asphalt aggregate was estimated according to the method specified in AASHTO T 308-10(2015).

[0091] Examples 2 and 3 Asphalt specimens T1-2 and T1-3 for wheel tracking tests were prepared in the same manner as in Example 1, except that the amount of compound B1 added was changed as shown in Table 2. Examples 4 to 8 Asphalt specimens T1-4 to T1-8 for wheel tracking tests were prepared in the same manner as in Example 1, except that compound B1 was changed to compounds B2 to B6 shown in Table 2. Examples 9 to 11 Asphalt specimens T1-9 to T1-11 for wheel tracking tests were prepared in the same manner as in Example 1, except that polyester resin A1 was changed to polyester resins A2 to A4 obtained in Production Examples 2 to 4 shown in Table 2. Example 12 An asphalt specimen T1-12 for wheel tracking test was prepared in the same manner as in Example 1, except that polyester resin A1 was not added. Comparative Example 1 An asphalt specimen T1-C1 for wheel tracking test was prepared in the same manner as in Example 1, except that polyester resin A1 and compound B1 were not added. Comparative Example 2 An asphalt specimen T1-C2 for the wheel tracking test and an asphalt specimen T2-C2 for the Marshall stability test were prepared in the same manner as in Example 1, except that Compound B1 was not added. Comparative Examples 3 to 5 Asphalt specimens T1-C3 to T1-C5 for wheel tracking tests were prepared in the same manner as in Example 1, except that compound B1 was changed to compounds C1 to C3 shown in Table 2.

[0092] Compounds B2 to B6 and C1 to C3 used in the examples are as follows. Compound B2: "ASFIER N480L"; beef tallow triamine (manufactured by Kao Corporation) Compound B3: "Kaowax EB-G"; ethylene bis(stearic acid amide) (Kao Corporation) Compound B4: "Rheodol SP-S10V"; sorbitan monostearate (manufactured by Kao Corporation) Compound B5: "Kalcol 2098"; lauryl alcohol (manufactured by Kao Corporation) Compound B6: "Farmin DM1098"; dimethyldecylamine (Kao Corporation) Compound C1: γ-aminobutyric acid Compound C2: n-heptanol Compound C3: "Gripper 4131"; a mixture of stearyl phosphate and phosphoric acid (manufactured by Kao Corporation)

[0093] [Rating(1)] The asphalt specimens for wheel tracking test T1-1 to T1-12 and T1-C1 to T1-C5 obtained in Examples 1 to 12 and Comparative Examples 1 to 5 were subjected to the following evaluation tests. <Durability evaluation: Rutting amount (wheel tracking test)> An asphalt specimen was immersed in hot water set to 65°C in a 60°C thermostatic chamber, and a wheel tracking tester (manufactured by Iwata Kogyosho Co., Ltd., load 686N, steel wheel width 47mm, linear pressure 291.5N / cm) was used to move a wheel back and forth over the specimen at a speed of 21 passes per minute, measuring the amount of displacement after 2,000 passes. Other measurement conditions followed the "B003 Wheel Tracking Test" described in the "Pavement Survey and Testing Methods Handbook" published by the Japan Road Association. The results are shown in Table 2.

[0094] <Evaluation of pavement blackness> Before the wheel tracking test, the asphalt specimen was measured for L at four randomly selected points using a portable color difference meter (TES-3250, manufactured by Sato Shoji Co., Ltd.).* a * b * L in color space * The average value was used as the measurement value before the test. After the wheel tracking test, the asphalt specimen was subjected to the same L test at four randomly selected locations from the wheel travel locations. * The average value was used as the measured value after the test. L before and after wheel tracking test * The index of change in value was calculated as [measured value before test / measured value after test]. The results are shown in Table 2.

[0095] In addition, L * a * b * L in color space * The value is a value between 0 and 100, which represents brightness, and the smaller the value, the darker the black, and the larger the value, the brighter the white. From the viewpoint of surface aesthetics and visibility, a darker black, i.e., a smaller value, is preferable. The closer the value of [measured value before test / measured value after test] is to 1.0, the better the blackness can be maintained. The asphalt specimen before the wheel tracking test corresponds to the asphalt pavement immediately after compaction, and the asphalt specimen after the wheel tracking test corresponds to the asphalt pavement that has deteriorated over time after opening to traffic.

[0096] [Table 2]

[0097] The results shown in Table 2 show that by using an asphalt modifier containing polyester resin (A) and a specified compound (B), it is possible to obtain an asphalt pavement that is excellent in durability and maintains its black color even after traffic is reopened, even when the aggregate contains recycled asphalt aggregate (for example, Examples 1 to 11).It is also clear that such effects can be achieved by using an asphalt modifier that does not contain polyester resin (A) but contains a specified compound (B) (for example, Example 12).

[0098] [Rating (2)] The asphalt specimens T2-1 and T2-C2 obtained in Example 1 and Comparative Example 2 for the Marshall stability test were subjected to the following evaluation tests. <Marshall stability test> The demolded asphalt specimen T2 was immersed in a 60°C water bath for 30 minutes, and then a Marshall loading device (manufactured by Nakajima Gihan Co., Ltd.) was used to crush the overturned asphalt specimen T2 with a flat plate at a speed of 50 mm / min. The maximum load until fracture was recorded as the Marshall stability. The amount of displacement from the start of the displacement slope to the maximum load was measured and used as the flow value. Other measurement conditions followed the "B001 Marshall Stability Test" described in the "Pavement Survey and Testing Methods Handbook" published by the Japan Road Association. The flow value of asphalt specimen T2-1 (Example 1) was 30 [1 / 100 cm], and the flow value of asphalt specimen T2-C2 (Comparative Example 2) was 18 [1 / 100 cm]. The flow value in the Marshall stability test is an indicator of the flexibility and crack resistance of asphalt pavement at the service temperature, and the higher the flow value, the better the flexibility and crack resistance of the asphalt pavement.

[0099] These results show that asphalt specimens obtained using an asphalt modifier containing polyester resin (A) and a specified compound (B) have superior flexibility and crack resistance compared to asphalt specimens that do not contain compound (B) (for example, compare Example 1 with Comparative Example 2).

Claims

1. The composition contains a polyester resin (A), the following compound (B), asphalt, and aggregate, The asphalt mixture wherein the aggregate contains recycled asphalt aggregate. Compound (B): a compound having 8 or more carbon atoms and having a hydroxyl group or an amino group

2. The asphalt mixture according to claim 1, wherein the compound (B) has 30 or less carbon atoms.

3. The asphalt mixture according to claim 1, wherein the compound (B) is one or more compounds selected from the group consisting of alkylamines, alkyl alcohols, sugar alcohols, and alkylamide compounds.

4. The asphalt mixture according to claim 1, wherein the mass ratio of the polyester resin (A) to the compound (B) [polyester resin (A) / compound (B)] is 4 or more and 39 or less.

5. The asphalt mixture according to claim 1, wherein the content of the recycled asphalt aggregate in the asphalt mixture is 10% by mass or more and 80% by mass or less.

6. 2. The asphalt mixture according to claim 1, wherein the softening point or melting point of the polyester resin (A) is 90°C or higher.

7. An asphalt modifier comprising a polyester resin (A) and the following compound (B): Compound (B): a compound having 8 or more carbon atoms and having a hydroxyl group or an amino group

8. A road paving method comprising a step of compacting and applying the asphalt mixture according to any one of claims 1 to 6, A road paving method in which the compaction temperature of the asphalt mixture is 100°C or higher and 200°C or lower.

9. An additive for recycled asphalt mixtures containing one or more compounds having 8 or more carbon atoms selected from alkylamines, alkyl alcohols, sugar alcohols, and alkylamide compounds.

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