Asphalt composition

Abstract

To provide an asphalt composition, an asphalt mixture, and a road pavement method which enable formation of a paved surface having excellent durability and flexibility.SOLUTION: An asphalt composition contains asphalt, a polyester resin, and a polymer having a main chain composed of an aromatic ring.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an asphalt composition, an asphalt mixture, 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 emulsion for slow setting that contains an amidoamine of a specific structure or a water-soluble salt thereof, a nonionic surfactant with an HLB value within a specific range, and a naphthalenesulfonic acid-formalin condensate of a specific structure, and that is not affected by the temperature during slurry seal construction or the properties of the aggregate used, can ensure sufficient aggregate mixing time without using a decomposition retarder, and provides slurry fluidity suitable for construction. Patent Document 2 discloses an asphalt composition that provides excellent durability of pavement surfaces after construction, which contains asphalt, a thermoplastic elastomer, and a specific amount of a polyester having a specific softening point, which contains 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-169719 [Patent Document 2] Japanese Patent Application Publication No. 2019-019663 Summary of the Invention [Problem to be solved by the invention]

[0005] When modifying asphalt with polyester resin, the high molecular weight component asphaltene forms an association / aggregation structure, which means that the polyester resin modification effect cannot be achieved efficiently. Therefore, when trying to achieve sufficient durability using this modifier, there was a problem that flexibility could be deteriorated. The present invention relates to an asphalt composition, an asphalt mixture, and a road paving method that maximize the asphalt modification effect of polyester resins and allow the formation of paved surfaces with excellent durability and flexibility. [Means for solving the problem]

[0006] The present invention relates to the following [1] to [3]. [1] An asphalt composition containing asphalt, a polyester resin, and a polymer whose main chain is composed of aromatic rings. [2] An asphalt mixture containing asphalt, aggregate, polyester resin, and a polymer whose main chain is composed of aromatic rings. [3] A road paving method comprising the step of applying the asphalt mixture according to [2] above to a road to form an asphalt pavement layer. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an asphalt composition, an asphalt mixture, and a road paving method that can form a paved surface having excellent durability and flexibility. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Asphalt composition] The asphalt composition contains asphalt, a polyester resin, and a polymer whose main chain is composed of aromatic rings.

[0009] The present inventors have discovered that by mixing a polymer whose main chain is composed of aromatic rings in combination with a polyester resin into an asphalt composition, an asphalt composition can be obtained that can form a pavement surface with excellent durability and flexibility. 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. The polymer of the present invention, whose main chain is composed of aromatic rings, can disperse asphaltene through π-π interactions, thereby increasing the frequency of contact with polyester resin, thereby making the interaction more efficient and achieving a high asphalt modification effect.

[0010] 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 resin, 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.

[0011] <Asphalt> Various types of asphalt can be used. Examples include straight asphalt, which is petroleum asphalt for paving, as well as modified asphalt. Examples of modified asphalt include blown asphalt and polymer-modified asphalt modified with polymeric materials such as thermoplastic elastomers and thermoplastic resins. Straight asphalt refers to the residual bituminous material obtained by subjecting crude oil to atmospheric distillation equipment, vacuum distillation equipment, etc. Blown asphalt refers to asphalt obtained by heating a mixture of straight asphalt and heavy oil and then 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. The modified asphalt is preferably a polymer-modified asphalt, more preferably a polymer-modified asphalt modified with a thermoplastic elastomer.

[0012] (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.

[0013] <Polyester resin> The polyester resin contained in the asphalt composition of the present invention is a polycondensate of an alcohol component and a carboxylic acid component, and contains structural units derived from an alcohol component and structural units derived from a carboxylic acid component. The polyester resin 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, anhydrides thereof, and alkyl esters thereof (for example, alkyl groups having 1 to 3 carbon atoms). Among these aromatic dicarboxylic acids, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred, from the viewpoints of suppressing aggregate scattering and water resistance.

[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 unit derived from polyethylene terephthalate) The polyester resin 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 contains structural units consisting of ethylene glycol and terephthalic acid derived from polyethylene terephthalate, the "structural units derived from alcohol components" include structural units derived from ethylene glycol derived from polyethylene terephthalate, and the "structural units derived from carboxylic acid components" include structural units derived from terephthalic acid derived from polyethylene terephthalate.

[0029] (Preferred embodiment of polyester resin) In a preferred embodiment of the polyester resin, from the viewpoint of ensuring compatibility with asphaltene in asphalt, the content of terephthalic acid in 100 mol% of the carboxylic acid component is preferably 20 mol% or more, more preferably 40 mol% or more, even more preferably 60 mol% or more, and preferably 100 mol% or less. Furthermore, in a preferred embodiment of the polyester resin, from the viewpoint of further improving durability through interaction with asphaltene in asphalt, the content of bisphenol A derivative in 100 mol% of the alcohol component is preferably 10 mol% or more, more preferably 20 mol% or more, even more preferably 30 mol% or more, and preferably 100 mol% or less.

[0030] The bisphenol A derivative is, for example, an alcohol component containing a structure represented by the following formula (i) or formula (ii).

[0031] [ka]

[0032] The phenylene group in formula (i) and the cyclohexylene group in formula (ii) may have a substituent such as a halogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an i-propyl group.

[0033] Examples of bisphenol A derivatives include bisphenol A, alkylene oxide adducts of bisphenol A, hydrogenated bisphenol A, and alkylene oxide adducts of hydrogenated bisphenol A. Of these, alkylene oxide adducts of bisphenol A and hydrogenated bisphenol A are preferred.

[0034] (Physical properties of polyester resin) From the viewpoint of durability and flexibility of the asphalt pavement, the softening point of the polyester resin is preferably 90°C or higher, more preferably 95°C or higher, even more preferably 100°C or higher, and preferably 140°C or lower, more preferably 130°C or lower, even more preferably 120°C or lower. From the same viewpoint, the weight average molecular weight Mw of the polyester resin is preferably 5,000 or more, more preferably 7,000 or more, even more preferably 8,000 or more, and preferably 70,000 or less, more preferably 40,000 or less, even more preferably 25,000 or less.

[0035] The softening point and weight average molecular weight Mw of the polyester resin can be measured by the method described in the Examples. The softening point and weight average molecular weight Mw can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0036] The polyester resin may be 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-11-133668, JP-A-10-239903, JP-A-8-20636, etc. A preferred modified polyester resin is a urethane-modified polyester resin obtained by urethane-extending a polyester resin with a polyisocyanate compound.

[0037] (Polyester resin content) The content of polyester resin is preferably 3 parts 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 asphalt from the viewpoint of improving durability, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less from the viewpoint of maintaining flexibility.

[0038] (Method of producing polyester resin) The method for producing the polyester resin contained in the modified asphalt composition 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 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 the durability and flexibility of the asphalt pavement.

[0039] 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 durability and flexibility 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.

[0040] 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.

[0041] <Polymer with aromatic main chain> The asphalt composition of the present invention contains a polymer whose main chain is composed of aromatic rings. Hereinafter, a polymer whose main chain is composed of aromatic rings may be referred to as an aromatic polymer. Aromatic polymers contain an aromatic ring skeleton on the main chain of the polymer's structural units. Examples of the aromatic ring skeleton include benzene, naphthalene, anthracene, tetracene, pentacene, triphenylene, and pyrene from the viewpoint of ensuring compatibility with asphaltene, and among these, naphthalene and anthracene are preferred from the viewpoints of availability and performance. The aromatic ring skeleton may have a substituent, such as an alkyl group such as a methyl group, an ethyl group, or a butyl group, and among these, a methyl group or an ethyl group is preferred from the viewpoint of ensuring compatibility with asphaltene. Examples of aromatic polymers include those obtained by addition polymerization, those obtained by sequential polymerization, particularly condensation polymerization, those obtained by ring-opening polymerization, those obtained by living polymerization, those obtained by aromatic nucleophilic substitution reaction (also called aromatic electrophilic substitution reaction), and polyphenylene sulfide, among which those obtained by condensation polymerization or aromatic nucleophilic substitution reaction are preferred. Among aromatic polymers obtained by condensation polymerization, those obtained by formalin condensation are preferred, and specific examples include naphthalenesulfonic acid formalin condensate, methylnaphthalenesulfonic acid formalin condensate, and butylnaphthalene / naphthalenesulfonic acid formalin condensate. Examples of aromatic polymers obtained by aromatic nucleophilic substitution reaction include aromatic polyether ketone (PEK) and aromatic polyether ether ketone (PEEK).

[0042] (Aromatic polymer content) The content of the polymer whose main chain is composed of aromatic rings is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, per 100 parts by mass of asphalt from the viewpoint of improving durability, and is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 3 parts by mass or less from the viewpoint of maintaining workability. From the viewpoint of improving durability, the mass ratio of the polyester resin to the aromatic polymer in the asphalt composition [(polyester resin) / (aromatic polymer)] is preferably 3 or more, more preferably 4 or more, even more preferably 5 or more, and is preferably 40 or less, more preferably 30 or less, even more preferably 25 or less.

[0043] 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.

[0044] [Method for producing asphalt composition] The method for producing the asphalt composition of the present invention preferably includes a step of mixing asphalt, the polyester resin, and the aromatic polymer.

[0045] The asphalt composition can be obtained by heating and melting asphalt, adding the polyester resin and aromatic polymer, and stirring and mixing until the components are uniformly dispersed using a commonly used mixer, such as a homomixer, dissolver, paddle mixer, ribbon mixer, screw mixer, planetary mixer, vacuum countercurrent mixer, roll mill, or twin-screw extruder.

[0046] From the viewpoint of uniformly dispersing the polyester resin and aromatic polymer in the asphalt, the mixing temperature of the asphalt with the polyester resin and aromatic polymer 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.

[0047] Furthermore, from the viewpoint of efficiently dispersing the polyester resin and aromatic polymer uniformly in the asphalt, the mixing time of the asphalt with the polyester resin and aromatic polymer 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.

[0048] [Asphalt mixture] The asphalt mixture of the present invention contains the asphalt, aggregate, the polyester resin, and the aromatic polymer.

[0049] The total content of the polyester resin and the aromatic polymer 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.

[0050] In the asphalt mixture of the present invention, the total content of the polyester resin and the aromatic polymer is, from the viewpoint of the durability of the asphalt pavement, preferably 1 part by mass, 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 preferably 30 parts by mass or less, more preferably 25 parts by mass or less, even more preferably 20 parts by mass or less.

[0051] <Aggregate> The aggregate can be selected from crushed stone, boulders, gravel, sand, recycled aggregate, ceramics, etc. In addition, the aggregate can be either coarse aggregate with a particle size of 2.36 mm or more, or fine aggregate with a particle size of less than 2.36 mm. Examples of coarse aggregate include crushed stone with a particle size range of 2.36 mm or more and less than 4.75 mm, crushed stone with a particle size range of 4.75 mm or more and less than 12.5 mm, crushed stone with a particle size range of 12.5 mm or more and less than 19 mm, and crushed stone with a particle size range of 19 mm or more and less than 31.5 mm. The fine aggregate preferably has a particle size of 0.075 mm or more and less than 2.36 mm. Examples of fine aggregate include river sand, dune sand, mountain sand, sea sand, crushed sand, fine sand, screenings, crushed stone dust, silica sand, artificial sand, glass cullet, foundry sand, and recycled crushed aggregate sand. The above particle size is a value specified in JIS A5001:2008. Among these, a combination of coarse aggregate and fine aggregate is preferred.

[0052] 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.

[0053] 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.

[0054] Suitable blending examples for asphalt mixtures include the following (1) to (3): (1) Fine-graded asphalt containing 30% to less than 45% by volume of coarse aggregate, 30% to 50% by volume of fine aggregate, and 5% to 10% by volume of asphalt composition. (2) An example of an asphalt mixture is a dense-graded asphalt containing 45% to less than 70% by volume of coarse aggregate, 20% to 45% by volume of fine aggregate, and 3% to 10% by volume of asphalt composition. (3) Porous asphalt containing 70% to 80% by volume of coarse aggregate, 10% to 20% by volume of fine aggregate, and 3% to 10% by volume of 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.

[0055] [Asphalt mixture manufacturing method] The method for producing an asphalt mixture of the present invention includes a step of mixing asphalt, heated aggregate, polyester resin, and the aromatic polymer. In the mixing step, the asphalt, heated aggregate, polyester resin, and aromatic polymer can be mixed simultaneously or in any order. From the viewpoint of durability and flexibility of the asphalt pavement, the aromatic polymer is preferably mixed with the heated aggregate simultaneously with or after the asphalt. Specific methods for producing asphalt mixtures include conventional methods for producing asphalt mixtures known as the plant mix method and the premix method. All of these methods involve adding the polyester resin and aromatic polymer to heated aggregate and asphalt (and a thermoplastic elastomer, if necessary). Examples of the addition method include a premix method in which asphalt (and a thermoplastic elastomer, if necessary), the polyester resin, and the aromatic polymer are dissolved in advance, or a plant mix method in which asphalt (and a thermoplastic elastomer, if necessary) is added to aggregate, and then the polyester resin and the aromatic polymer are added simultaneously or in any order. Of these, the plant mix method is preferred from the viewpoint of exhibiting 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 as needed) to heated aggregate to obtain a mixture, then adding the polyester resin and the aromatic polymer, and mixing the mixture with the polyester resin; (ii) Adding and mixing asphalt (and optionally a thermoplastic elastomer), the polyester resin, and the aromatic polymer simultaneously to the heated aggregate, or (iii) A mixture of asphalt (and thermoplastic elastomer, if necessary), the polyester resin, and the aromatic polymer, which has been pre-heat mixed, is added to the heated aggregate and mixed. Among these, from the viewpoint of efficiently dispersing the asphalt component, the mixing step is preferably the method (i) in which asphalt and heated aggregate are mixed, and then the polyester resin and the aromatic polymer are mixed.

[0056] The temperature when asphalt, the polyester resin, and the aromatic polymer are mixed with the 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 asphalt, the polyester resin, and the aromatic polymer 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.

[0057] In the above methods (i) to (iii), the method for preparing a mixture of asphalt (and a thermoplastic elastomer, if necessary), polyester resin, and the aromatic polymer is not particularly limited, but preferably includes a step of heating and melting the asphalt, adding the polyester resin, the aromatic polymer, and, if necessary, other additives, and stirring and mixing the components in a commonly used mixer until they are uniformly dispersed. Commonly used mixers include a homomixer, dissolver, paddle mixer, ribbon mixer, screw mixer, planetary mixer, vacuum countercurrent mixer, roll mill, twin-screw extruder, etc.

[0058] The mixing temperature for the asphalt, polyester resin, and aromatic polymer 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 and aromatic polymer 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.

[0059] Furthermore, the mixing time for asphalt, polyester resin, and aromatic polymer 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 and aromatic polymer 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 and salt powder relative to the asphalt are as described above.

[0060] In the above methods (i) to (iii), the mixture of asphalt, the polyester resin, and the aromatic polymer 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, the polyester resin, and the aromatic polymer preferably does not substantially contain water.

[0061] 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.

[0062] [Road paving construction method] The asphalt mixture of the present invention is suitable for road paving. The road paving 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.

[0063] 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 layer of a road.

[0064] 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. [Example]

[0065] 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.

[0066] (1) Softening point of polyester resin 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.

[0067] (2) Weight average molecular weight (Mw) of polyester resin 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)

[0068] Production Example 1 (Polyester Resin A-1) The raw materials listed in Table 1, except for alkenyl succinic anhydride, 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. The amount of tin(II) di(2-ethylhexanoate) listed in Table 1 was added under a nitrogen atmosphere. The mixture was heated to 235°C over 3 hours in a mantle heater and maintained at 235°C for 5 hours. After visually confirming the disappearance of PET particles from the reaction mixture, the mixture was cooled to 180°C. After cooling to 180°C, alkenyl succinic anhydride was added, the mixture was heated to 210°C over 2 hours, maintained at 210°C for 1 hour, and reacted under reduced pressure of 8.3 kPa until the softening point listed in Table 1 was reached, yielding the target polyester resin 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).

[0069] Production Example 2 (Polyester Resin B-1) The raw materials listed in Table 1, except for alkenyl succinic anhydride, 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 listed 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 of 8.3 kPa, and the reaction was continued until the softening point listed in Table 1 was reached, yielding the target polyester resin B-1.

[0070] [Table 1]

[0071] Example 1 15 kg of aggregate heated to 180°C (see below for aggregate composition) was placed in an asphalt mixer and mixed at 180°C for 60 seconds. 820 g of straight asphalt (manufactured by Mitsubishi Corporation Energy Corporation) was then added and mixed for 1 minute in the asphalt mixer. 82 g of polyester resin A-1 and 16 g of aromatic polymer P-1 (Demol MS (trade name), manufactured by Kao Corporation, methylnaphthalenesulfonic acid formalin condensate) were then added and mixed for 2 minutes in the asphalt mixer to obtain an asphalt mixture. <Aggregate composition> No. 6 crushed stone 40.0 parts by mass No. 7 crushed stone 13.0 parts by mass Crushed sand 10.0 parts by mass River sand 22.0 parts by mass Mountain sand 10.0 parts by mass Stone powder (calcium carbonate) 5.0 parts by mass Passed mass%: Sieve size 15 mm: 100% by mass Sieve size 10 mm: 88.7% by mass Sieve size 5 mm: 60.5% by mass Sieve size 2.5 mm: 42.6% by mass Sieve size 1.2 mm: 29.9% by mass Sieve size 0.6 mm: 19.8% by mass Sieve size 0.3 mm: 11.5% by mass Sieve size 0.15mm: 6.2% by mass

[0072] [evaluation] <Evaluation of rutting amount (wheel tracking test)> The resulting asphalt mixture was quickly filled into a 300 x 300 x 50 mm formwork and stored at 180°C for 2 hours for thermal curing. After that, 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 produce asphalt specimen M-1a. Asphalt specimen M-1a 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 1716N, 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 15 round trips per minute, measuring the amount of displacement after 1,250 round trips. 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 amount of rutting in the wheel tracking test is an indicator of the durability of the asphalt pavement. The results are shown in Table 2.

[0073] <Flow value evaluation: Marshall stability test> 1.2 kg of the resulting asphalt mixture was weighed and stored at 180°C for 2 hours for thermal curing. It was then 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 M-1b. The demolded asphalt specimen M-1b 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 M-1b with a flat plate at a rate of 50 mm / min, and the amount of displacement from the start of the slope of the displacement 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 Method Handbook" published by the Japan Road Association. The flow value is used as an indicator of the flexibility and crack resistance of asphalt pavement at operating temperatures. The results are shown in Table 2.

[0074] Examples 2 to 8, Comparative Examples 1 to 3 Asphalt specimens were prepared in the same manner as in Example 1, except that the blending ratio was changed to that shown in Table 2, and the amount of rutting and flow value were evaluated. The results are shown in Table 2.

[0075] The aromatic polymers used in Examples 1 to 8 and Comparative Example 3 are shown below. Aromatic polymer P-1: Demol MS (trade name), manufactured by Kao Corporation, sodium salt of methylnaphthalenesulfonic acid formalin condensate Aromatic polymer P-2: Demol SN-B (trade name), manufactured by Kao Corporation, sodium salt of butylnaphthalene / naphthalenesulfonic acid formalin condensate Aromatic polymer P-3: Demol N (trade name), manufactured by Kao Corporation, sodium salt of β-naphthalenesulfonic acid formalin condensate Aromatic polymer P-4: Demol T (trade name), manufactured by Kao Corporation, sodium salt of β-naphthalenesulfonic acid formalin condensate (excessive amount of sodium sulfate) Aromatic polymer P-5: Mighty 100 (product name), manufactured by Kao Corporation, naphthalenesulfonic acid formalin condensate, high molecular weight type Aromatic polymer P-6: Torelina (trade name), model number: 3A30, manufactured by Toray Industries, Inc., polyphenylene sulfide film; crushed using a coffee mill before use.

[0076] [Table 2]

[0077] The results shown in Table 2 show that the present invention can provide asphalt pavement with excellent durability and flexibility. In particular, Examples 1 and 2 have excellent durability with particularly small amounts of rutting, and also have low flow values ​​and excellent flexibility. On the other hand, Comparative Example 1, which does not contain the aromatic polymer of the present invention, shows a large amount of rutting, poor durability, and a high flow value, resulting in insufficient flexibility. Comparative Example 2, which contains a large amount of polyester resin, shows sufficient durability, but an even higher flow value and poor flexibility. Comparative Example 3, which does not contain polyester resin, shows extremely poor durability.

Claims

1. An asphalt composition containing asphalt, a polyester resin, and a polymer whose main chain is composed of aromatic rings, the polymer having a main chain composed of an aromatic ring is at least one selected from the group consisting of a naphthalenesulfonic acid-formalin condensate, a methylnaphthalenesulfonic acid-formalin condensate, a butylnaphthalene / naphthalenesulfonic acid-formalin condensate, and polyphenylene sulfide; The content of the polyester resin is 3 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the asphalt, The content of the polymer whose main chain is composed of an aromatic ring is 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the asphalt, An asphalt composition, wherein the mass ratio of the polyester resin to the polymer whose main chain is composed of aromatic rings [(polyester resin) / (polymer whose main chain is composed of aromatic rings)] is 3 or more and 40 or less.

2. 2. The asphalt composition according to claim 1, wherein the polyester resin contains structural units derived from an alcohol component and structural units derived from a carboxylic acid component, and contains 20 mol% or more of terephthalic acid relative to 100 mol% of the carboxylic acid component.

3. 3. The asphalt composition according to claim 1 or 2, wherein the asphalt is straight asphalt or modified asphalt.

4. The asphalt composition of claim 3, wherein the modified asphalt is a thermoplastic elastomer-modified asphalt.

5. An asphalt mixture containing asphalt, aggregate, polyester resin, and a polymer whose main chain is composed of aromatic rings, the polymer having a main chain composed of an aromatic ring is at least one selected from the group consisting of a naphthalenesulfonic acid-formalin condensate, a methylnaphthalenesulfonic acid-formalin condensate, a butylnaphthalene / naphthalenesulfonic acid-formalin condensate, and polyphenylene sulfide; The content of the polyester resin is 3 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass of the asphalt, The content of the polymer whose main chain is composed of an aromatic ring is 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the asphalt, An asphalt mixture, wherein the mass ratio of the polyester resin to the polymer whose main chain is composed of aromatic rings [(polyester resin) / (polymer whose main chain is composed of aromatic rings)] is 3 or more and 40 or less.

6. A road paving method, comprising the step of applying the asphalt mixture according to claim 5 to a road to form an asphalt pavement layer.

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