Asphalt modifier for modified asphalt

Abstract

To provide an asphalt modifier for a modified asphalt capable of forming a paved surface having excellent rutting resistance and surface aesthetic.SOLUTION: An asphalt modifier for modified asphalt containing a polyester (A) and a polyester (B). (A) contains a constituent unit derived from an alcohol component (a1) and a constituent unit derived from a carboxylic acid component (a2), a total content of the alcohol and carboxylic acid components having a structure X represented by residues excluding two hydroxyl groups from bisphenol A in total 100 mol% of the (a1) and (a2) is 10 mol% or larger, (B) contains a constituent unit derived from the alcohol component (b1) and a constituent unit derived the carboxylic acid component (b2), in total 100 mol% of the (b1) and (b2), a total content of the alcohol component and carboxylic acid component having an aliphatic saturated hydrocarbon skeleton is 20 mol% or larger, and, a total content of the alcohol component and carboxylic acid component having a structure X is smaller than 5 mol%.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Asphalt pavement, which uses asphalt mixture, is used for paving roads, parking lots, freight yards, sidewalks, etc., because it is relatively easy to lay and the time from the start of paving work to the start of traffic is short. Asphalt pavement is formed by an asphalt mixture in which aggregate is bound with asphalt, the paved road has good hardness and durability. However, asphalt pavement surfaces deteriorate over time, requiring repairs, which increases maintenance costs and significantly impacts automobile traffic.

[0003] Patent Document 1 discloses an asphalt composition containing asphalt, a thermoplastic elastomer, and a specific amount of polyester, the polyester having a specific softening point and glass transition point. Patent Document 2 discloses an asphalt composition containing asphalt and a polyester polymer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-19325 [Patent Document 2] Japanese Patent Application Publication No. 04-8766 Summary of the Invention [Problem to be solved by the invention]

[0005] When asphalt is modified with polyester containing bisphenol A, rutting on the pavement surface after construction is suppressed, resulting in a pavement surface with excellent rutting resistance (rutting resistance) and a beautiful surface appearance. However, there is a demand for asphalt mixtures that can produce pavement surfaces with even better rutting resistance. In particular, rutting resistance can sometimes be insufficient in specially formulated asphalt pavements, such as drainage pavements and thin-layer pavements, which tend to require insufficient thermal curing. The present invention relates to an asphalt modifier for modified asphalt to obtain an asphalt mixture that forms a paved surface having even better rutting resistance and surface aesthetics, 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 [5]. [1] An asphalt modifier for modified asphalt comprising a polyester (A) and a polyester (B), The polyester (A) contains a structural unit derived from an alcohol component (a1) and a structural unit derived from a carboxylic acid component (a2), and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is 10 mol % or more relative to 100 mol % in total of the alcohol component (a1) and the carboxylic acid component (a2): The polyester (B) contains structural units derived from an alcohol component (b1) and structural units derived from a carboxylic acid component (b2), and the total content of the alcohol component having an aliphatic saturated hydrocarbon skeleton and the carboxylic acid component is 20 mol% or more, and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is less than 5 mol%, based on a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2):

[0007] [ka]

[0008] [2] An asphalt mixture comprising modified asphalt, aggregate, the polyester (A) described in [1] above, and the polyester (B) described in [1] above. [3] An asphalt mixture obtained by blending modified asphalt, aggregate, the polyester (A) described in [1] above, and the polyester (B) described in [1] above. [4] A method for producing the asphalt mixture according to [2] or [3] above, comprising a step of mixing modified asphalt, heated aggregate, polyester (A) and polyester (B). [5] A road paving method comprising the step of applying the asphalt mixture according to [2] or [3] above to a road to form an asphalt pavement layer. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an asphalt modifier for modified asphalt, an asphalt mixture and a method for producing the same, and a road paving method, which are used to obtain an asphalt mixture that forms a paved surface with even better rutting resistance and surface aesthetics. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Asphalt modifier for modified asphalt] The asphalt modifier for modified asphalt of the present invention comprises a blend of polyester (A) and polyester (B), The polyester (A) contains a structural unit derived from an alcohol component (a1) and a structural unit derived from a carboxylic acid component (a2), and the total content of the alcohol component having a structure represented by formula (1) and the carboxylic acid component is 10 mol % or more relative to 100 mol % in total of the alcohol component (a1) and the carboxylic acid component (a2), The polyester (B) contains a structural unit derived from an alcohol component (b1) and a structural unit derived from a carboxylic acid component (b2), and the total content of the alcohol component having an aliphatic saturated hydrocarbon skeleton and the carboxylic acid component is 20 mol % or more, and the total content of the alcohol component having a structure represented by formula (1) and the carboxylic acid component is less than 5 mol %, based on a total of 100 mol % of the alcohol component (b1) and the carboxylic acid component (b2).

[0011] [ka]

[0012] The present inventors have discovered that by incorporating a combination of a specified polyester (A) and a polyester (B) into an asphalt mixture containing polymer-modified asphalt, a pavement surface having even better rutting resistance and surface aesthetics can be formed. 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. Asphalt components are broadly classified into asphaltenes and maltenes. In the present invention, it is presumed that polyester (A) having a specific structure effectively modifies asphaltene to improve the hardness of the pavement, and polyester (B) having a specific structure effectively modifies maltene to impart adhesion to aggregate. Furthermore, since polyester (A) and polyester (B) each have a specific structure that enhances compatibility between the polyesters and with each other and with the other components, the effects of each are exerted synergistically, resulting in excellent rutting resistance in the asphalt mixture and high durability, which is thought to provide an excellent surface appearance.

[0013] The definitions of various terms used in this specification are shown below. The term "binder mixture" refers to a mixture containing asphalt and a thermoplastic elastomer, and is a concept that includes, for example, asphalt modified with the thermoplastic elastomer described below (hereinafter also referred to as "modified asphalt"). In the polyester, 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.

[0014] <Polyester (A)> From the viewpoint of rutting resistance and surface aesthetics of asphalt pavement, polyester (A) contains structural units derived from alcohol component (a1) and structural units derived from carboxylic acid component (a2), and out of a total of 100 mol% of alcohol component (a1) and carboxylic acid component (a2), the total content of alcohol component and carboxylic acid component having a structure represented by formula (1) is 10 mol% or more, preferably 20 mol% or more, more preferably 25 mol% or more, even more preferably 40 mol% or more, and preferably 70 mol% or less, preferably 60 mol% or less, even more preferably 55 mol% or less.

[0015] [ka]

[0016] (Structure represented by formula (1)) The structure represented by formula (1) is a 4,4'-isopropylidenediphenyl structure. In one preferred embodiment of the present invention, the structure represented by formula (1) is a structure containing a bisphenol A skeleton represented by the following formula (1').

[0017] [ka]

[0018] The structure represented by formula (1) may be present in both the alcohol component (a1) and the carboxylic acid component (a2), or in either the alcohol component (a1) or the carboxylic acid component (a2), and preferably in only the alcohol component (a1).

[0019] When only the alcohol component (a1) has the structure represented by formula (1), the content of the alcohol component having the structure represented by formula (1) in the alcohol component (a1) is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 25 mol% or more, and even more preferably 40 mol% or more. The content of the alcohol component having the structure represented by formula (1) may be 90 mol% or more, 95 mol% or more, or 100 mol%.

[0020] (Alcohol component (a1)) Examples of the alcohol component (a1) include diols, trihydric or higher polyhydric alcohols, etc. Examples of the diols include aliphatic diols, aromatic diols, etc. These alcohol components can be used alone or in combination of two or more. From the viewpoint of rutting resistance and surface appearance of the asphalt pavement, the alcohol component (a1) preferably contains an alkylene oxide adduct of bisphenol A, and more preferably contains an alkylene oxide adduct of bisphenol A represented by the following formula (I):

[0021] [ka]

[0022] [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.

[0023] Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a propylene oxide adduct of bisphenol A [2,2-bis(4-hydroxyphenyl)propane] 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.

[0024] From the viewpoint of rutting resistance and surface appearance of the asphalt pavement, the content of the alkylene oxide adduct of bisphenol A is preferably 20 mol% or more, more preferably 25 mol% or more, and even more preferably 30 mol% or more, based on 100 mol% of the alcohol component (a1), and is preferably 100 mol% or less.

[0025] 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. Examples of the polyhydric alcohol having a valence of three or more include trihydric alcohols, etc. Examples of the polyhydric alcohol having a valence of three or more include glycerin, etc.

[0026] (Carboxylic acid component (a2)) Examples of the carboxylic acid component (a2) include aliphatic dicarboxylic acid compounds, aromatic dicarboxylic acid compounds, and polycarboxylic acid compounds having a carboxylic acid value of 3 to 6. These carboxylic acid components can be used alone or in combination of two or more.

[0027] The number of carbon atoms in the main chain of the aliphatic dicarboxylic acid is preferably 3 or more, more preferably 4 or more, and preferably 10 or less, more preferably 8 or less, from the viewpoint of rutting resistance and surface appearance of the asphalt pavement. Examples of aliphatic dicarboxylic acid compounds include 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, and succinic acid substituted with an alkyl group having from 1 to 20 carbon atoms or an alkenyl group having from 2 to 20 carbon atoms. Examples of substituted succinic acids include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Among the above aliphatic dicarboxylic acid compounds, succinic acid substituted with an alkenyl group having from 2 to 20 carbon atoms is preferred.

[0028] Examples of aromatic dicarboxylic acid compounds include phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc. Among these aromatic dicarboxylic acid compounds, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred, from the viewpoints of rutting resistance and surface appearance of asphalt pavement. The trivalent or more and hexavalent polycarboxylic acid compound is preferably a tricarboxylic acid. Examples of trivalent or more and hexavalent polycarboxylic acid compounds include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, and pyromellitic acid. When a polycarboxylic acid compound is contained, from the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monocarboxylic acid compound.

[0029] From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the content of the aliphatic dicarboxylic acid compound in the carboxylic acid component (a2) is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, and is preferably 40 mol% or less, more preferably 30 mol% or more, even more preferably 25 mol% or less. From the viewpoint of rutting resistance and surface appearance of the asphalt pavement, the content of the aromatic dicarboxylic acid compound is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 75 mol%, and is 100 mol% or less, preferably 98 mol% or less, more preferably 95 mol% or less, even more preferably 90 mol% or less, based on 100 mol% of the carboxylic acid component.

[0030] In one preferred embodiment of the present invention, the carboxylic acid component (a2) contains a total of 50 mol% or more of one or more selected from the group consisting of terephthalic acid and isophthalic acid, and from the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, this is preferably 75 mol% or more, more preferably 90 mol% or more, and preferably 100 mol% or less.

[0031] (Mole ratio of carboxylic acid component (a2) to alcohol component (a1)) The molar ratio of the carboxylic acid component (a2) to the alcohol component (a1) [carboxylic acid component (a2) / alcohol component (a1)] is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, from the viewpoint of adjusting the acid value and from the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, and is preferably 1.5 or less, more preferably 1.3 or less, even more preferably 1.1 or less.

[0032] (Structural unit derived from polyethylene terephthalate) The polyester (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 (A) contains structural units derived from ethylene glycol and terephthalic acid derived from polyethylene terephthalate, the "structural units derived from the alcohol component (a1)" contain structural units derived from ethylene glycol derived from polyethylene terephthalate, and the "structural units derived from the carboxylic acid component (a2)" contain structural units derived from terephthalic acid derived from polyethylene terephthalate.

[0033] (Physical properties of polyester (A)) From the viewpoint of rutting resistance and surface appearance of the asphalt pavement, the softening point of the polyester (A) is preferably 90°C or higher, more preferably 95°C or higher, even more preferably 100°C or higher, and is preferably 140°C or lower, more preferably 130°C or lower, even more preferably 120°C or lower. From the viewpoint of rutting resistance and surface appearance of the asphalt pavement, the hydroxyl value of the polyester (A) is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, and preferably 70 mgKOH / g or less, more preferably 60 mgKOH / g or less, even more preferably 40 mgKOH / g or less, and even more preferably 30 mgKOH / g or less. The weight average molecular weight Mw of the polyester (A) is preferably 5,000 or more, more preferably 7,000 or more, even more preferably 8,000 or more, from the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, and is preferably 70,000 or less, more preferably 40,000 or less, even more preferably 25,000 or less.

[0034] The softening point, hydroxyl value, and weight average molecular weight Mw of the polyester (A) can be measured by the methods described in the Examples. The softening point, hydroxyl value, and weight average molecular weight Mw can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0035] [Polyester (B)] The polyester (B) contains a structural unit derived from an alcohol component (b1) and a structural unit derived from a carboxylic acid component (b2), and the total content of the alcohol component having an aliphatic saturated hydrocarbon skeleton and the carboxylic acid component is 20 mol % or more, and the total content of the alcohol component having a structure represented by the above-mentioned formula (1) and the carboxylic acid component is less than 5 mol %, based on a total of 100 mol % of the alcohol component (b1) and the carboxylic acid component (b2).

[0036] (Aliphatic saturated hydrocarbon skeleton) The total content of the alcohol component and carboxylic acid component having an aliphatic saturated hydrocarbon skeleton is 20 mol% or more, based on a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2). From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the total content is preferably 25 mol% or more, more preferably 30 mol% or more, and even more preferably 40 mol% or more, and is preferably 85 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less. The aliphatic saturated hydrocarbon skeleton may be contained in both the alcohol component (b1) and the carboxylic acid component (b2), or in either the alcohol component (b1) or the carboxylic acid component (b2). Preferably, the alcohol component (b1) and the carboxylic acid component (b2), or only the alcohol component (b1), contain the aliphatic saturated hydrocarbon skeleton. From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the number of carbon atoms in the aliphatic saturated hydrocarbon skeleton is preferably 5 or more, and preferably 100 or less, more preferably 50 or less, even more preferably 20 or less, and even more preferably 10 or less.

[0037] (Structure represented by formula (1)) The total content of the alcohol component and carboxylic acid component having the structure represented by formula (1) is less than 5 mol % out of a total of 100 mol % of the alcohol component (b1) and the carboxylic acid component (b2). From the viewpoint of the rutting resistance and surface aesthetics of the asphalt pavement, the total content is preferably less than 1 mol %, more preferably less than 0.1 mol %, and even more preferably is substantially free of the structure represented by formula (1). [ka]

[0038] In a preferred embodiment of the polyester (B), the total content of the alcohol component having an aromatic ring skeleton and the carboxylic acid component is preferably 15 mol% or more, more preferably 20 mol% or more, even more preferably 40 mol% or more, and is preferably 70 mol% or less, more preferably 60 mol% or less, even more preferably 55 mol% or less, based on a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2). The aromatic ring skeleton can be derived from both the alcohol component (b1) and the carboxylic acid component (b2), or from either the alcohol component (b1) or the carboxylic acid component (b2), and is preferably derived from the carboxylic acid component (b2). The aromatic ring skeleton is derived from, for example, the above-mentioned aromatic diol or aromatic dicarboxylic acid, preferably from an aromatic dicarboxylic acid, more preferably from terephthalic acid or isophthalic acid.

[0039] In a preferred embodiment of polyester (B), the total content of alcohol components and carboxylic acid components having an aliphatic saturated hydrocarbon skeleton having 5 to 100 carbon atoms is 30 mol% to 85 mol% out of a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2). From the viewpoint of rutting resistance and surface appearance of asphalt pavement, it is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more, and preferably 82 mol% or less, more preferably 80 mol% or less, even more preferably 78 mol% or less. In addition, the total content of alcohol components and carboxylic acid components having an aromatic ring skeleton is 15 mol% or more. From the viewpoint of rutting resistance and surface appearance of asphalt pavement, it is preferably 20 mol% or more, more preferably 40 mol% or more, even more preferably 45 mol% or more, and preferably 70 mol% or less, more preferably 60 mol% or less, even more preferably 55 mol% or less.

[0040] (Alcohol component (b1)) Examples of the alcohol component (b1) include diols and trihydric or higher polyhydric alcohols. Examples of the diols include aliphatic diols and aromatic diols. These alcohol components can be used alone or in combination of two or more. From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the aliphatic diol is preferably a saturated aliphatic diol, more preferably an α,ω-straight chain saturated aliphatic diol. The aliphatic diol preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms, and even more preferably 5 or more carbon atoms, and preferably has 100 or less carbon atoms, more preferably 50 or less carbon atoms, more preferably 20 or less carbon atoms, and even more preferably 10 or less carbon atoms.

[0041] Examples of saturated aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-eicosanediol, and other saturated aliphatic diols having 100 or less carbon atoms. Among these, ethylene glycol, 1,5-pentanediol, 1,6-hexanediol, and 1,9-nonanediol are preferred. These saturated aliphatic diols can be used alone or in combination of two or more. From the viewpoint of rutting resistance and surface appearance of the asphalt pavement, the content of saturated aliphatic diol is preferably 20 mol% or more, more preferably 40 mol% or more, and even more preferably 50 mol% or more, based on 100 mol% of the alcohol component (b1), and is preferably 100 mol% or less. The alcohol component (b1) may contain other alcohol components different from the saturated aliphatic diol. Examples of other alcohol components include aromatic diols such as alkylene oxide adducts of bisphenol A, and trihydric or higher alcohols such as glycerin, pentaerythritol, and trimethylolpropane. These alcohol components may be used alone or in combination of two or more.

[0042] In a preferred embodiment of the alcohol component (b1), the content of saturated aliphatic diols having 5 to 100 carbon atoms is preferably 60 mol % or more, more preferably 70 mol % or more, based on 100 mol % of the alcohol component (b1).

[0043] (Carboxylic acid component (b2)) Examples of the carboxylic acid component (b2) include aliphatic monocarboxylic acids, aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and polycarboxylic acid compounds having a valence of 3 to 6. From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the carboxylic acid component is preferably an aliphatic dicarboxylic acid or an aromatic dicarboxylic acid, more preferably an aromatic dicarboxylic acid. These carboxylic acid components can be used alone or in combination of two or more. From the viewpoint of rutting resistance and surface appearance of the asphalt pavement, the number of carbon atoms in the main chain of the aliphatic dicarboxylic acid is preferably 4 or more, more preferably 5 or more, even more preferably 6 or more, and preferably 20 or less, more preferably 18 or less, even more preferably 16 or less. Examples of aliphatic dicarboxylic acids include fumaric acid, sebacic acid, dodecanedioic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and eicosanedioic acid. Among these, sebacic acid is preferred. These aliphatic dicarboxylic acids can be used alone or in combination of two or more. The number of carbon atoms of the aromatic dicarboxylic acid is preferably 8 or more, and preferably 20 or less, more preferably 16 or less, and even more preferably 12 or less, from the viewpoint of the rutting resistance and surface appearance of the asphalt pavement. Examples of aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, anthracenedicarboxylic acid, and phenanthrenedicarboxylic acid. Among these, terephthalic acid is preferred. These aromatic dicarboxylic acids can be used alone or in combination of two or more. From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the content of the aliphatic dicarboxylic acid or aromatic dicarboxylic acid in the carboxylic acid component (b2) is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and even more preferably 95 mol% or more, and is 100 mol% or less. The carboxylic acid component (b2) may contain other carboxylic acid components different from aliphatic dicarboxylic acids and aromatic dicarboxylic acids. Examples of other carboxylic acid components include aliphatic monocarboxylic acids such as stearic acid, capric acid, lauric acid, myristic acid, palmitic acid, arachidic acid, behenic acid, and lignoceric acid; and trivalent or higher polycarboxylic acids such as trimellitic acid and pyromellitic acid. These carboxylic acid components may be used alone or in combination of two or more.

[0044] In a preferred embodiment of the carboxylic acid component (b2), the total content of one or more selected from terephthalic acid and isophthalic acid is preferably 30 mol % or more, more preferably 40 mol % or more, in the carboxylic acid component (b2).

[0045] (molar ratio of carboxylic acid component (b2) to alcohol component (b1)) The molar ratio of the carboxylic acid component (b2) to the alcohol component (b1) [carboxylic acid component (b2) / alcohol component (b1)] is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, from the viewpoint of adjusting the acid value and from the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, and is preferably 1.5 or less, more preferably 1.3 or less, even more preferably 1.1 or less.

[0046] (Physical properties of polyester (B)) From the viewpoint of rutting resistance and surface appearance of asphalt pavement, the hydroxyl value of the polyester (B) is preferably 5 mgKOH / g or more, more preferably 10 mgKOH / g or more, even more preferably 15 mgKOH / g or more, and is preferably 70 mgKOH / g or less, more preferably 60 mgKOH / g or less, even more preferably 40 mgKOH / g or less. The weight average molecular weight Mw of the polyester (B) is preferably 3,000 or more, more preferably 5,000 or more, even more preferably 7,000 or more, from the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, and is preferably 50,000 or less, more preferably 30,000 or less, even more preferably 20,000 or less.

[0047] The hydroxyl value and weight average molecular weight Mw of the polyester (B) can be measured by the method described in the Examples. The hydroxyl value and weight average molecular weight Mw can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0048] The polyester (A) and the polyester (B) may be modified to such an extent that their properties are not substantially impaired. Specific examples of modified polyesters include polyesters 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 is a urethane-modified polyester obtained by urethane-extending polyester with a polyisocyanate compound.

[0049] From the viewpoint of rutting resistance of the asphalt pavement, the content of polyester (A) in the asphalt modifier for modified asphalt is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 80% by mass or more, and is preferably 95% by mass or less, more preferably 90% by mass or less. From the viewpoint of rutting resistance of the asphalt pavement, the content of polyester (B) in the asphalt modifier for modified asphalt is preferably 5% by mass or more, more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 20% by mass or less.

[0050] From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the content ratio of polyester (A) to polyester (B) in the asphalt modifier for modified asphalt is, in mass ratio, polyester (A) / polyester (B), preferably 60 / 40 or more, more preferably 65 / 45 or more, even more preferably 70 / 30 or more, even more preferably 75 / 25 or more, and even more preferably 80 / 20 or less, and is preferably 99 / 1 or less, more preferably 98 / 2 or less, even more preferably 97 / 3 or less, even more preferably 95 / 5 or less, and even more preferably 90 / 10 or less. That is, polyester (A) is a base material for the polyester, and polyester (B) is an auxiliary material for the polyester.

[0051] (Polyester manufacturing method) The method for producing the polyester (A) and polyester (B) constituting the asphalt modifier for modified asphalt of the present invention is not particularly limited, but they can be produced, for example, by polycondensing the above-mentioned alcohol component (a1) and carboxylic acid component (a2), and the above-mentioned alcohol component (b1) and carboxylic acid component (b2). The temperature of the polycondensation reaction is not particularly limited, but is preferably 160° C. or higher and 260° C. or lower in terms of adjusting the reactivity and improving the rutting resistance and surface appearance of the asphalt pavement.

[0052] When the polyester 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 to 80 mass%, more preferably 15 to 70 mass%, and even more preferably 25 to 60 mass%, 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 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 rutting resistance and surface aesthetics 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 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.

[0053] In the polycondensation reaction, a tin(II) compound not having a Sn-C bond, such as tin(II) di(2-ethylhexanoate), may be used as an esterification catalyst, and from the viewpoint of reaction rate, the amount used is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, even more preferably 0.2 part by mass or more, and preferably 1.5 parts by mass or less, more preferably 0.6 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 esterification catalyst, from the viewpoint of reaction rate, a pyrogallol compound such as gallic acid may be used as a co-catalyst in the polycondensation reaction, preferably in an amount of 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, and even more preferably 0.05 part 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, from the viewpoint of reaction rate, 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, per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0054] (Preferred embodiment of asphalt modifier for modified asphalt) Preferred embodiments of the asphalt modifier for modified asphalt of the present invention include the following first and second preferred embodiments. A first preferred embodiment is an asphalt modifier for modified asphalt comprising a polyester (A) and a polyester (B), The polyester (A) contains structural units derived from an alcohol component (a1) and structural units derived from a carboxylic acid component (a2), in which the alcohol component (a1) contains 90 mol % or more of an alcohol component having a structure represented by formula (1), and the carboxylic acid component (a2) contains a total of 50 mol % or more of one or more acids selected from terephthalic acid and isophthalic acid, The polyester (B) is an asphalt modifier for modified asphalt, which comprises structural units derived from an alcohol component (b1) and structural units derived from a carboxylic acid component (b2), wherein the alcohol component (b1) comprises 50 mol% or more of a saturated aliphatic diol having from 2 to 12 carbon atoms, and the carboxylic acid component (b2) comprises a total of 50 mol% or more of one or more selected from terephthalic acid and isophthalic acid, and the total content of the alcohol component and the carboxylic acid component having the structure represented by formula (1) is less than 5 mol%. In a first preferred embodiment, the ratio of the contents of polyester (A) and polyester (B) in the asphalt modifier for modified asphalt is preferably polyester (A) / polyester (B) in mass ratio of 60 / 40 or more and 90 / 10 or less.

[0055] A second preferred embodiment is an asphalt modifier comprising a polyester (A) and a polyester (B), The polyester (A) contains structural units derived from an alcohol component (a1), structural units derived from a carboxylic acid component (a2), and structural units derived from polyethylene terephthalate, wherein the alcohol component (a1) contains 10 mol % or more of an alcohol component having a structure represented by formula (1), the content of ethylene glycol in the alcohol component is 50 mol % or more, and the total content of one or more acids selected from terephthalic acid and isophthalic acid in the carboxylic acid component is 50 mol % or more; The polyester (B) is an asphalt modifier for modified asphalt, which comprises structural units derived from an alcohol component (b1) and structural units derived from a carboxylic acid component (b2), wherein the alcohol component (b1) comprises 50 mol % or more of a saturated aliphatic diol having from 2 to 12 carbon atoms, and the carboxylic acid component (b2) comprises 50 mol % or more of one or more selected from terephthalic acid and isophthalic acid, and the total content of the alcohol component and the carboxylic acid component having the structure represented by formula (1) is less than 5 mol %.

[0056] In a second preferred embodiment in which the polyester (A) contains structural units derived from polyethylene terephthalate, the content of ethylene glycol in the alcohol component is the content of ethylene glycol in the total content of the alcohol component (a1) and the ethylene glycol derived from polyethylene terephthalate, i.e., the content of structural units derived from ethylene glycol in the total content of structural units derived from the alcohol component (a1) and the ethylene glycol derived from polyethylene terephthalate. Furthermore, the total content of one or more selected from terephthalic acid and isophthalic acid in the carboxylic acid component is the total content of one or more selected from terephthalic acid and isophthalic acid in the total content of terephthalic acid derived from carboxylic acid component (a2) and polyethylene terephthalate. That is, it is the content of structural units derived from terephthalic acid and isophthalic acid in the total content of structural units derived from carboxylic acid component (a2) and structural units derived from ethylene glycol derived from polyethylene terephthalate. In a second preferred embodiment, the ratio of polyester (A) to polyester (B) in the asphalt modifier for modified asphalt is preferably polyester (A) / polyester (B) by mass ratio of 60 / 40 or more and 90 / 10.

[0057] The asphalt modifier for modified asphalt of the present invention can be used, for example, by mixing with modified asphalt to obtain an asphalt composition. The asphalt modifier for modified asphalt of the present invention further modifies the modified asphalt so that a paved surface having even better rutting resistance and surface aesthetics is formed. Heated aggregate is added to the obtained asphalt composition to form an asphalt mixture, which can then be used for paving. The asphalt modifier for modified asphalt of the present invention can be suitably used as an asphalt modifier for modified asphalt to be blended into asphalt mixtures containing aggregate.

[0058] [Asphalt mixture] The asphalt mixture of the present invention comprises modified asphalt, aggregate, polyester (A), and polyester (B). The asphalt mixture of the present invention is also formed by blending modified asphalt, aggregate, polyester (A), and polyester (B). The asphalt mixture of the present invention is suitable for paving, and is particularly suitable for road paving. <Asphalt> The asphalt mixture of the present invention contains modified asphalt as the asphalt. Examples of modified asphalt include blown asphalt, which is obtained by heating a mixture of straight asphalt and heavy oil and then oxidizing it by blowing air into it, and polymer-modified asphalt, which is asphalt modified with a polymer material such as a thermoplastic elastomer or a thermoplastic resin. The modified asphalt is preferably a polymer-modified asphalt, more preferably a polymer-modified asphalt modified with a thermoplastic elastomer.

[0059] <Thermoplastic elastomer> Examples of thermoplastic elastomers in polymer-modified asphalt modified with thermoplastic elastomers 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. The thermoplastic elastomer in the modified asphalt is preferably 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, and ethylene / acrylic acid ester copolymers. Among these, from the viewpoint of rutting resistance 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 rutting resistance and surface appearance 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 20% by mass or less, even more preferably 10% by mass or less.

[0060] <Aggregate> Aggregates can be selected from crushed stone, boulders, gravel, sand, recycled aggregate, ceramics, etc. In addition, both coarse aggregate with a particle size of 2.36 mm or more and 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.

[0061] 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. Of these, calcium carbonate is preferred from the viewpoint of improving the strength of the asphalt pavement. From the viewpoint of improving dry strength, the average particle size of the filler is preferably 0.001 mm or more, and preferably 0.06 mm or less, more preferably 0.04 mm or less, and even more preferably 0.03 mm or less. The average particle size of the filler can be measured using a laser diffraction particle size distribution analyzer. Here, the average particle size means the average particle size at 50% cumulative volume.

[0062] From the viewpoint of the rutting resistance of the asphalt pavement, the mass ratio of coarse aggregate to fine aggregate is preferably 10 / 90 or more, more preferably 20 / 80 or more, even more preferably 30 / 70 or more, and is preferably 90 / 10 or less, more preferably 80 / 20 or less, even more preferably 70 / 30 or less.

[0063] Suitable examples of blending in asphalt mixtures include the following (1) to (3). (1) For example, 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) For example, dense-graded asphalt containing 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) For example, 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.

[0064] The porous asphalt can be suitably used for drainage pavement.

[0065] From the viewpoints of rutting resistance and surface aesthetics, the aggregate content in the asphalt mixture is preferably 50% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less, even more preferably 96% by mass or less.

[0066] 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 modified asphalt, polyester (A) and polyester (B). However, it is not necessary to be limited to the method described in the "Guidelines for Pavement Design and Construction" and it may be determined by other methods.

[0067] From the viewpoint of the rutting resistance of the asphalt pavement, the content of modified asphalt in the asphalt mixture is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less.

[0068] (Polyester content) The total content of polyester (A) and polyester (B) in the asphalt mixture of the present invention is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, per 100 parts by mass of modified asphalt, from the viewpoint of rutting resistance and surface appearance of the asphalt pavement, and from the viewpoint of workability, it is preferably 40 parts by mass or less, more preferably 35 parts by mass or less, and more preferably 30 parts by mass or less. From the viewpoint of the rutting resistance and surface appearance of the asphalt pavement, the content ratio of polyester (A) to polyester (B) in the asphalt mixture is preferably polyester (A) / polyester (B) by mass ratio of 60 / 40 or more, more preferably 65 / 45 or more, even more preferably 70 / 30 or more, even more preferably 75 / 25 or more, even more preferably 80 / 20 or more, and is preferably 99 / 1 or less, more preferably 98 / 2 or less, even more preferably 97 / 3 or less, even more preferably 95 / 5 or less, even more preferably 90 / 10 or less.

[0069] The asphalt mixture may further contain other components as required.

[0070] [Asphalt mixture manufacturing method] The asphalt mixture of the present invention can be obtained by blending modified asphalt, heated aggregate, polyester (A), and polyester (B). The method for producing an asphalt mixture of the present invention includes a step of mixing modified asphalt, heated aggregate, polyester (A), and polyester (B) simultaneously or in any order. 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 polyester to heated aggregate. The mixing step is preferably any one of the following steps (i) to (iii). (i) adding and mixing modified asphalt to heated aggregate, and then adding and mixing polyester (A) and polyester (B); (ii) Adding and mixing the modified asphalt, polyester (A) and polyester (B) simultaneously to the heated aggregate, or (iii) A mixture of modified asphalt, polyester (A) and polyester (B) that has been pre-heat mixed is added to the heated aggregate and mixed.

[0071] The polyester (A) and the polyester (B) may be added simultaneously or separately in a sequential order. When the polyesters are added separately in a sequential order, the polyester (B) may be added after the polyester (A), or the polyester (A) may be added after the polyester (B).

[0072] The temperature of the heated aggregate in methods (i) to (iii) is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, from the viewpoint of the rutting resistance 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 modified asphalt.

[0073] The mixing temperature of the aggregate with the modified asphalt and / or polyester is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, from the viewpoint of the rutting resistance 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 modified asphalt. The mixing time of the aggregate with the modified asphalt and / or polyester is not particularly limited, but is preferably 30 seconds or more, more preferably 1 minute or more, and even more preferably 2 minutes or more. The upper limit of the time is not particularly limited, but is preferably about 30 minutes.

[0074] From the viewpoint of the rutting resistance of the asphalt pavement, the method for producing an asphalt mixture preferably includes a step of holding the resulting mixture at the above-mentioned mixing temperature after the mixing step. In the step of holding the asphalt mixture, the mixture may be further mixed. The retention time is preferably 0.2 hours or more, more preferably 0.3 hours or more, and even more preferably 0.5 hours or more. The upper limit of the time is not particularly limited, but is, for example, about 5 hours.

[0075] [Road paving method] The asphalt mixture of the present invention is suitable for road paving and 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 1) of mixing modified asphalt, the polyester (A) and polyester (B), and aggregate to obtain an asphalt mixture, and a step (step 2) of applying the asphalt mixture obtained in step 1 to a road to form an asphalt pavement layer. The asphalt pavement layer is usually a base layer or a surface layer, and is preferably a surface layer from the viewpoint of exhibiting the effects of rut resistance and surface aesthetics.

[0076] From the viewpoint of rutting resistance and surface aesthetics, the thickness of the asphalt pavement layer is preferably 3 cm or more, more preferably 4 cm or more, even more preferably 4.5 cm or more, and preferably 7 cm or less, more preferably 6 cm or less, even more preferably 5.5 cm or less. In another embodiment of the present invention, the asphalt pavement layer can be a thin-layer pavement, and the thickness of the surface layer is preferably 1 cm or more, more preferably 1.5 cm or more, even more preferably 2 cm or more, and preferably 4 cm or less, more preferably 3.5 cm or less, even more preferably 3 cm or less. The asphalt mixture may be compacted and applied in the same manner using a known construction machine. When used as a heated asphalt mixture, the compaction temperature is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 130°C or higher, from the viewpoint of the rutting resistance of the asphalt pavement, and is preferably 200°C or lower, more preferably 180°C or lower. [Example]

[0077] Various physical properties were measured and evaluated by the following methods. In the following examples and comparative examples, parts and percentages are by mass unless otherwise specified.

[0078] (1) Hydroxyl value of polyester The hydroxyl value of the polyester was 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)).

[0079] (2) Softening point of polyester 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.

[0080] (3) Weight average molecular weight (Mw) of polyester The weight average molecular weight was determined by gel permeation chromatography (GPC) according to the following method. (i) Preparation of sample solution The sample was dissolved in chloroform at 40°C to a concentration of 0.5 g / 100 mL. Next, this solution was filtered using a PTFE-type membrane filter "DISMIC-25JP" (manufactured by Toyo Roshi Kaisha, Ltd.) with a pore size of 0.20 μm to remove insoluble components, and a sample solution was obtained. (ii) Molecular weight measurement The following measurement equipment and analytical column were used, and chloroform was used as the eluent at a flow rate of 1 mL per minute. The column was stabilized in a thermostatic chamber at 40°C. 200 μL of sample solution was injected into the column and the measurement was performed. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curve used here was prepared using several types of monodisperse polystyrene (A-500 (5.0 × 10) manufactured by Tosoh Corporation). 2 ), A-1000(1.01×10 3 ), A-2500(2.63×10 3 ), A-5000(5.97×10 3 ), F-1(1.02×10 4 ), F-2(1.81×10 4 ), F-4(3.97×10 4 ), F-10(9.64×10 4 ), F-20(1.90×10 5 ), F-40(4.27×10 5 ), F-80(7.06×10 5 ), F-128(1.09×10 6 )) was used as a standard sample. The molecular weight is shown in parentheses. Measuring device: "HLC-8320GPC" (Tosoh Corporation) Analytical column: "TSKgel Super HZM" + "TSKgel Super H-RC" x 2 (Tosoh Corporation)

[0081] Production Example 1 (Polyester A-1) The polyester alcohol components and terephthalic acid shown in Table 1 were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirrer, a downflow condenser, and a nitrogen inlet tube. In a nitrogen atmosphere, tin(II) di(2-ethylhexanoate) and gallic acid were added in the amounts shown in Table 1. The mixture was heated to 235°C over 3 hours in a mantle heater, maintained at 235°C for 5 hours, and then cooled to 180°C. After cooling to 180°C, alkenyl succinic anhydride was added, and the mixture was heated to 210°C over 2 hours and maintained at 210°C for 1 hour. The reaction was carried out under reduced pressure at 8.3 kPa, and the reaction was continued until the softening point shown in Table 1 was reached, yielding the target polyester A-1. The alkenyl succinic anhydride used had an average number of moles added of 12 and a molecular weight of 256 (calculated from GC-MS and saponification value).

[0082] Production Example 2 (Polyester B-1) The raw materials shown in Table 1, except for adipic acid, were placed in a 10-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube. In a nitrogen atmosphere, the amounts of tin(II) di(2-ethylhexanoate) and gallic acid shown in Table 1 were added, and the mixture was heated to 235°C over 3 hours in a mantle heater. After reaching 235°C, the mixture was maintained for 5 hours. After visually confirming that the PET particles had disappeared from the reaction mixture, the mixture was cooled to 180°C. Next, adipic acid was added, and the mixture was heated from 180°C to 210°C over 3 hours. After reaching 210°C, the reaction was continued at 10 kPa until the softening point shown in Table 1 was reached, yielding Polyester B-1.

[0083] [Table 1]

[0084] Production Examples 3 and 5 to 7 (Polyesters A-2, C-2, D-2 and E-2) The raw material monomers shown in Table 2 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 the amounts of tin(II) di(2-ethylhexanoate) and gallic acid shown in Table 2 were added under a nitrogen atmosphere. The mixture was maintained at 180°C for 2 hours, then heated to 210°C over 3 hours, and reacted at 210°C for 4 hours, and then reacted at 8.3 kPa for 1 hour to obtain polyesters A-2, C-2, D-2, and E-2.

[0085] Production Example 4 (Polyester B-2) The raw material monomers shown in Table 2 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 in the amounts shown in Table 2 were added under a nitrogen atmosphere. The mixture was maintained at 180°C for 2 hours under a nitrogen atmosphere, and then heated to 210°C over 3 hours, after which a reaction was carried out at 210°C for 4 hours. After cooling to 150°C, sebacic acid was added, the mixture was heated to 200°C over 5 hours, and then reacted at 8.3 kPa for 1 hour to obtain polyester B-2.

[0086] Production Example 8 (Polyester F-2) The raw material monomers shown in Table 2 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 the amounts of tin(II) di(2-ethylhexanoate) and gallic acid shown in Table 2 were added under a nitrogen atmosphere. The mixture was maintained at 140°C for 6 hours, and then heated to 200°C over 6 hours. The mixture was then reacted at 200°C for 1 hour, and then reacted at 8.3 kPa for 1 hour to obtain polyester F-2.

[0087] [Table 2]

[0088] The abbreviations for the alcohol components and carboxylic acid components used are as follows: EG: ethylene glycol 1,5-PD: 1,5-pentanediol 1,6-HD: 1,6-hexanediol 1,9-ND: 1,9-nonanediol 1,2-PD: 1,2-propanediol BPA-EO: Polyoxyethylene (2.2 moles) adduct of bisphenol A BPA-PO: Polyoxypropylene (2.2 moles) adduct of bisphenol A SA: Sebacic acid TPA: terephthalic acid ADA: adipic acid ASAN: alkenyl succinic anhydride

[0089] Example 1 As a binder mixture, 1,000 g of modified type II asphalt (manufactured by Toa Road Industry Co., Ltd.) heated to 180°C was placed in a 3-L stainless steel container and stirred at 100 rpm. Next, 170 g of polyester A-1 (17 parts by mass per 100 parts by mass of asphalt) was gradually added, followed immediately by the gradual addition of 30 g of polyester A-2 (3 parts by mass per 100 parts by mass of asphalt). The mixture was stirred at 300 rpm for 2 hours to produce asphalt composition (AS-1).

[0090] Next, 15 kg of aggregate heated to 180°C (see below for the composition of the aggregate) was placed in an asphalt mixer and mixed for 60 seconds at 180°C. Next, 986 g of the asphalt composition (AS-1) was added, and the mixture was mixed in the asphalt mixer for 2 minutes. The resulting asphalt mixture was quickly filled into a 300 x 300 x 50 mm formwork. Using a roller compactor (manufactured by Iwata Kogyosho Co., Ltd.), the mixture was subjected to 25 rotations at a temperature of 150°C and a load of 0.44 kPa to prepare an asphalt specimen (M-1a) without heat curing. Separately, an asphalt specimen (M-1b) was prepared under normal curing conditions following the same procedure as described above, except that the asphalt mixture was stored at 180°C for 2 hours before being filled into a formwork.

[0091] <Aggregate composition> No. 6 crushed stone 50.9 parts by mass Crushed sand 1 10.4 parts by mass Crushed sand 2 22.1 parts by mass Fine sand 10.4 parts by mass Stone powder (calcium carbonate) 6.2 parts by mass Passed mass%: Sieve size 15 mm: 100% by mass Sieve size 10 mm: 85.6% by mass Sieve size 5 mm: 49.7% by mass Sieve size 2.5 mm: 44.6% by mass Sieve size 1.2 mm: 31.6% by mass Sieve size 0.6 mm: 21.3% by mass Sieve size 0.3 mm: 12.7% by mass Sieve size 0.15mm: 7.1% by mass

[0092] [evaluation] The asphalt specimen (M-1a) and asphalt specimen (M-1b) described above were subjected to the following evaluation tests. The effects of heat curing were evaluated by comparing the evaluation results of asphalt specimen (M-1a) and asphalt specimen (M-1b). <Amount of rutting> The asphalt specimen was immersed in hot water set to 60°C in a 60°C thermostatic chamber, and a wheel tracking tester (manufactured by Iwata Kogyosho Co., Ltd., load 1,370 N, steel wheel width 47 mm, linear pressure 291.5 N / cm) was used to move a wheel back and forth over the specimen at a speed of 15 passes per minute, measuring the amount of displacement after 2,500 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 3.

[0093] Examples 2 to 8, Comparative Examples 1 to 3 Asphalt specimens were prepared in the same manner as in Example 1, except for changing the formulation as shown in Table 3. 945 g of the asphalt composition was used in Example 2, 822 g in Comparative Example 1, and 986 g in the other cases. An evaluation test of the strength development was conducted, and the results are shown in Table 3.

[0094] [Table 3]

[0095] The results in Table 3 show that the asphalt mixture of the present invention, which contains a combination of the specified polyester (A) and the specified polyester (B), exhibits low rutting in asphalt specimens produced under normal curing conditions, exhibits excellent adhesive strength, and is excellent in rutting resistance. In particular, when the specific polyester (B) is included, even asphalt specimens produced without heat curing exhibit excellent rutting resistance. Furthermore, the asphalt mixture of the present invention has excellent surface aesthetics, and is expected to form pavement surfaces with excellent rutting resistance in specially formulated asphalt pavements such as drainage pavements and thin-layer pavements.

Claims

1. An asphalt modifier for modified asphalt comprising a polyester (A) and a polyester (B), The polyester (A) contains a structural unit derived from an alcohol component (a1) and a structural unit derived from a carboxylic acid component (a2), and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is 10 mol % or more relative to 100 mol % in total of the alcohol component (a1) and the carboxylic acid component (a2): The polyester (B) contains a structural unit derived from an alcohol component (b1) and a structural unit derived from a carboxylic acid component (b2), and, based on a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2), the total content of the alcohol component having an aliphatic saturated hydrocarbon skeleton and the carboxylic acid component is 20 mol% or more, and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is less than 5 mol%, the alcohol component (b1) contains a diol, the diol comprises an aliphatic diol, The asphalt modifier for modified asphalt, wherein the aliphatic diol has 3 or more and 20 or less carbon atoms. 【Chemistry 1】

2. 2. The asphalt modifier for modified asphalt according to claim 1, wherein the content of alkylene oxide adduct of bisphenol A in the alcohol component (a1) is 20 mol% or more.

3. The asphalt modifier for modified asphalt according to claim 1 or 2, wherein the hydroxyl value of the polyester (A) is 10 mg KOH / g or more and 60 mg KOH / g or less.

4. The asphalt modifier for modified asphalt according to any one of claims 1 to 3, wherein the content of one or more selected from terephthalic acid and isophthalic acid in the carboxylic acid component (b2) is 30 mol% or more.

5. The asphalt modifier for modified asphalt according to any one of claims 1 to 4, wherein the hydroxyl value of the polyester (B) is 10 mg KOH / g or more and 60 mg KOH / g or less.

6. The asphalt modifier for modified asphalt according to any one of claims 1 to 5, wherein the mass ratio of polyester (A) to polyester (B) is 60 / 40 or more and 99 / 1 or less.

7. An asphalt mixture comprising a modified asphalt, an aggregate, a polyester (A), and a polyester (B), The polyester (A) contains a structural unit derived from an alcohol component (a1) and a structural unit derived from a carboxylic acid component (a2), and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is 10 mol % or more relative to 100 mol % in total of the alcohol component (a1) and the carboxylic acid component (a2): The polyester (B) contains a structural unit derived from an alcohol component (b1) and a structural unit derived from a carboxylic acid component (b2), and, based on a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2), the total content of the alcohol component having an aliphatic saturated hydrocarbon skeleton and the carboxylic acid component is 20 mol% or more, and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is less than 5 mol%, the alcohol component (b1) contains a diol, the diol comprises an aliphatic diol, The asphalt mixture, wherein the aliphatic diol has 3 or more and 20 or less carbon atoms. 【Chemistry 2】

8. An asphalt mixture comprising modified asphalt, aggregate, polyester (A) and polyester (B), The polyester (A) contains a structural unit derived from an alcohol component (a1) and a structural unit derived from a carboxylic acid component (a2), and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is 10 mol % or more relative to 100 mol % in total of the alcohol component (a1) and the carboxylic acid component (a2): The polyester (B) contains a structural unit derived from an alcohol component (b1) and a structural unit derived from a carboxylic acid component (b2), and, based on a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2), the total content of the alcohol component having an aliphatic saturated hydrocarbon skeleton and the carboxylic acid component is 20 mol% or more, and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is less than 5 mol%, the alcohol component (b1) contains a diol, the diol comprises an aliphatic diol, The asphalt mixture, wherein the aliphatic diol has 3 or more and 20 or less carbon atoms. 【Transformation 3】

9. The asphalt mixture according to claim 7 or 8, wherein the total content of the polyester (A) and the polyester (B) is 1 part by mass or more and 40 parts by mass or less per 100 parts by mass of the modified asphalt.

10. The asphalt mixture according to any one of claims 7 to 9, wherein the modified asphalt is a polymer-modified asphalt.

11. 11. The asphalt mixture of claim 10, wherein the modified asphalt is a polymer-modified asphalt modified with a thermoplastic elastomer.

12. 12. The asphalt mixture of claim 11, wherein the thermoplastic elastomer is 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, and ethylene / acrylic acid ester copolymers.

13. A method for producing an asphalt mixture, comprising a step of mixing modified asphalt, heated aggregate, polyester (A), and polyester (B), The polyester (A) contains a structural unit derived from an alcohol component (a1) and a structural unit derived from a carboxylic acid component (a2), and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is 10 mol % or more relative to 100 mol % in total of the alcohol component (a1) and the carboxylic acid component (a2): The polyester (B) contains a structural unit derived from an alcohol component (b1) and a structural unit derived from a carboxylic acid component (b2), and, based on a total of 100 mol% of the alcohol component (b1) and the carboxylic acid component (b2), the total content of the alcohol component having an aliphatic saturated hydrocarbon skeleton and the carboxylic acid component is 20 mol% or more, and the total content of the alcohol component and the carboxylic acid component having a structure represented by the following formula (1) is less than 5 mol%, the alcohol component (b1) contains a diol, the diol comprises an aliphatic diol, The method for producing an asphalt mixture, wherein the aliphatic diol has 3 or more and 20 or less carbon atoms. 【Chemistry 4】

14. A road paving method comprising the step of applying the asphalt mixture according to any one of claims 7 to 12 to a road to form an asphalt pavement layer.

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