Asphalt Modifier

Abstract

To provide an asphalt modifier for obtaining an asphalt mixture that forms a paved surface having excellent rutting resistance even with a short mixing time of the asphalt mixture, an asphalt mixture and a method for producing the same, and a method for paving a road.SOLUTION: An asphalt modifier comprises a polyester containing a constitutional unit derived from an alcohol component and a constitutional unit derived from a carboxylic acid component, with an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an asphalt modifier, 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 polyester resin, and a dispersant, which has excellent storage stability at high temperatures and high dry strength. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-030996 Summary of the Invention [Problem to be solved by the invention]

[0005] It is known that modifying asphalt with polyester can achieve excellent durability of asphalt pavement. However, due to the high affinity between polyester and aggregate, the polyester must be sufficiently dispersed in the asphalt by mechanical force, which may require a relatively long mixing time for the asphalt mixture. If it were possible to shorten the mixing time, it would be possible to improve construction efficiency, shorten the time traffic restrictions caused by asphalt paving work, and hopefully alleviate congestion. However, with conventional technology, shortening the mixing time could sometimes reduce the durability of the asphalt pavement. The present invention relates to an asphalt modifier for obtaining an asphalt mixture that forms a pavement surface having excellent rutting resistance even when the asphalt mixture is mixed for a short time, 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 [4]. [1] An asphalt modifier containing a polyester that contains a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component and has an amine value of 5 mg KOH / g or more and 100 mg KOH / g or less. [2] An asphalt mixture comprising asphalt, aggregate, polyester, and calcium carbonate powder, The polyester contains structural units derived from alcohol components and structural units derived from carboxylic acid components, and the asphalt mixture has an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less. [3] A method for producing an asphalt mixture, comprising a step of mixing asphalt, heated aggregate, calcium carbonate powder, and the polyester, wherein the polyester contains a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component, and has an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less. [4] 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 modifier for obtaining an asphalt mixture that forms a pavement surface with excellent rutting resistance even when the asphalt mixture is mixed for a short time, an asphalt mixture and a method for producing the same, and a road paving method. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Asphalt modifier] The asphalt modifier of the present invention comprises a polyester that contains structural units derived from an alcohol component and structural units derived from a carboxylic acid component and has an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less.

[0009] The inventors have discovered that by incorporating a specific polyester as an asphalt modifier into an asphalt mixture, a pavement surface with excellent rutting resistance can be formed even if the asphalt mixture is mixed for a short time. 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. When producing an asphalt mixture, if the mixing time is insufficient, polyester may become localized in the asphalt mixture. When polyester becomes localized, there will be areas with a low amount of polyester and areas where the polyester remains localized as coarse clumps. In the former, the adhesive strength will be weak, and in the latter, the polyester will not be able to sufficiently interact with the asphalt to modify it, which will result in an increase in the fluid component and reduced durability. In conventional technology, the polar functional groups of the polyester, i.e., carboxyl and hydroxyl groups, tend to interact with the filler component, causing agglomerations of the polyester and filler. Once agglomerations form, agitation is required to break them up, which requires a sufficiently long mixing time. In the present invention, a structural unit having a predetermined amine value, typically derived from an amino alcohol or amino carboxylic acid, is present at the end of the polyester, increasing the tendency of the polyester to be positively charged. This is thought to suppress the generation of aggregates due to, for example, charge repulsion with the filler component. As a result, it is thought that fine dispersion of the polyester can be achieved in a shorter time, and sufficient durability can be exhibited even with a shorter mixing time.

[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, 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 carboxyl group of a carboxylic acid component. The term "carboxylic acid compound" 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 compound 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 compound.

[0011] <Polyester> The polyester contains a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component, and has an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less. The alcohol component, the carboxylic acid component, and the physical properties of the polyester resin will be described below.

[0012] (alcohol content) Examples of the alcohol component include aliphatic diols, alicyclic diols, aromatic diols, trihydric or higher polyhydric alcohols, amino alcohols, etc. These alcohol components can be used alone or in combination of two or more.

[0013] 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.

[0014] Examples of alicyclic diols include hydrogenated bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane), alkylene oxide adducts of hydrogenated bisphenol A, cyclohexanediol, and cyclohexanedimethanol.

[0015] 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):

[0016] [ka]

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

[0018] Examples of 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.

[0019] 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.

[0020] 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.

[0021] As the amino alcohol, from the viewpoint of shortening the mixing time, an amino alcohol having a dialkylamino group is preferable, and an amino alcohol represented by the following formula (1a) is more preferable.

[0022] [ka]

[0023] [In the formula, R 11 and R 12 each independently represents a hydrocarbon group having 1 to 20 carbon atoms; and X represents a hydrocarbon group having 2 to 20 carbon atoms.

[0024] R 11 and R 12 has 1 or more carbon atoms and preferably 15 or less, more preferably 10 or less, and even more preferably 4 or less. X is preferably a saturated hydrocarbon group, and has 2 or more carbon atoms and 15 or less, more preferably 10 or less, and even more preferably 5 or less.

[0025] Examples of the amino alcohol represented by the following formula (1a) include 3-(dimethylamino)-1-propanol, dimethylaminoethanol, 3-(diethylamino)-1-propanol, and 2-diethylaminoethanol, and among these, 3-(dimethylamino)-1-propanol is preferred.

[0026] (carboxylic acid component) Examples of the carboxylic acid component include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, polycarboxylic acids having a valence of 3 or more and a valence of 6 or less, aminocarboxylic acids, etc. These carboxylic acid components can be used alone or in combination of two or more.

[0027] 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.

[0028] 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 viewpoint of rutting resistance.

[0029] 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.

[0030] 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.

[0031] The aminocarboxylic acid is preferably an aminocarboxylic acid having a dialkylamino group, more preferably an aminocarboxylic acid represented by the following formula (1b).

[0032] [ka]

[0033] [In the formula, R 11 and R 12 each independently represents a hydrocarbon group having 1 to 20 carbon atoms; and Y represents a hydrocarbon group having 1 to 20 carbon atoms.

[0034] R 11 and R 12 has 1 or more carbon atoms and preferably 15 or less, more preferably 10 or less, and even more preferably 4 or less. X is preferably a saturated hydrocarbon group, and has 1 or more carbon atoms and preferably 15 or less, more preferably 10 or less, and even more preferably 5 or less.

[0035] An example of the aminocarboxylic acid represented by the following formula (1b) is dimethylaminoglycine.

[0036] (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.

[0037] (Preferred embodiment of polyester) In a preferred embodiment of the polyester, the alcohol component contains an amino alcohol as a constituent unit having an amino group, or the carboxylic component contains an amino carboxylic acid as a constituent unit having an amino group. The amino alcohol and amino carboxylic acid are believed to cap the terminal functional groups of the polyester and provide the polyester with amino groups. When the alcohol component contains an amino alcohol, the content of the amino alcohol is preferably 2 mol% or more, more preferably 4 mol% or more, even more preferably 6 mol% or more, and preferably 20 mol% or less, more preferably 16 mol% or less, even more preferably 12 mol% or less, based on 100 mol% of the alcohol component. In a preferred embodiment of the polyester, from the viewpoint of rutting resistance, the alcohol component contains an alkylene oxide adduct of bisphenol A. The content of the alkylene oxide adduct of bisphenol A is preferably 20 mol % or more, more preferably 30 mol % or more, and preferably 100 mol % or less, based on 100 mol % of the alcohol component. In a preferred embodiment of the polyester, the carboxylic acid component contains at least one selected from the group consisting of terephthalic acid and isophthalic acid from the viewpoint of rutting resistance. The total content of terephthalic acid and isophthalic acid is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and preferably 100 mol% or less.

[0038] (molar ratio of carboxylic acid component to alcohol component) From the viewpoint of rutting resistance of asphalt pavement, the molar ratio of carboxylic acid component to alcohol component [carboxylic acid component / alcohol component] is preferably 0.6 or more, more preferably 0.7 or more, even more preferably 0.8 or more, and is preferably 1.5 or less, more preferably 1.3 or less, even more preferably 1.1 or less.

[0039] (Physical properties of polyester) The softening point of the polyester is preferably 80°C or higher, more preferably 85°C or higher, and even more preferably 90°C or higher from the viewpoint of rutting resistance, and is preferably 140°C or lower, more preferably 130°C or lower, even more preferably 125°C or lower, and even more preferably 120°C or lower from the viewpoint of shortening the mixing time.

[0040] From the viewpoint of rutting resistance, the glass transition point of the polyester is preferably 30°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and even more preferably 55°C or higher, and is preferably 80°C or lower, more preferably 70°C or lower, and even more preferably 65°C or lower.

[0041] The acid value of the polyester is preferably 1 mgKOH / g or more, more preferably 2 mgKOH / g or more, from the viewpoint of rutting resistance, and is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and even more preferably 15 mgKOH / g or less, from the viewpoint of shortening the mixing time.

[0042] From the viewpoint of rutting resistance, the hydroxyl value of the polyester is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, even more preferably 5 mgKOH / g or more, and is preferably 50 mgKOH / g or less, more preferably 40 mgKOH / g or less.

[0043] The amine value of the polyester is 5 mgKOH / g or more, preferably 7 mgKOH / g or more, more preferably 9 mgKOH / g or more, and 100 mgKOH / g or less from the viewpoint of shortening the mixing time, and is preferably 70 mgKOH / g or less, more preferably 50 mgKOH / g or less, and even more preferably 30 mgKOH / g or less from the viewpoint of rutting resistance.

[0044] The softening point, glass transition point, acid value, hydroxyl value, and amine value of the polyester can be measured by the methods described in the Examples. The softening point, glass transition point, acid value, hydroxyl value, and amine value can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0045] (Polyester manufacturing method) The method for producing the polyester constituting the asphalt modifier of the present invention is not particularly limited, but it can be produced, for example, by polycondensing the alcohol component and carboxylic acid component described above. The temperature of the polycondensation reaction is not particularly limited, but is preferably 160° C. or higher and 260° C. or lower from the viewpoint of adjusting the reactivity.

[0046] 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% 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 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 rutting resistance of 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.

[0047] In the polycondensation reaction, from the viewpoint of reaction rate, a tin(II) compound having no Sn-C bond, such as tin(II) di(2-ethylhexanoate), can be used as an esterification catalyst. The amount of the esterification catalyst 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, a pyrogallol compound such as gallic acid can be used as a promoter in the polycondensation reaction from the viewpoint of reaction rate. The amount of the promoter used is preferably 0.001 part by mass or more, more preferably 0.005 part by mass or more, even more preferably 0.01 part by mass or more, and preferably 0.15 part by mass or less, more preferably 0.10 part by mass or less, even more preferably 0.05 part by mass or less, relative to 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.

[0048] The asphalt modifier of the present invention can be used, for example, by mixing it with asphalt to obtain an asphalt composition. Heated aggregate is added to the obtained asphalt composition to form an asphalt mixture, which can then be used for paving. The asphalt modifier of the present invention can be suitably used as an asphalt modifier to be blended into asphalt mixtures containing aggregate.

[0049] [Asphalt mixture] The asphalt mixture of the present invention contains asphalt, aggregate, the polyester, and calcium carbonate powder. The asphalt mixture of the present invention is also formed by blending asphalt, the polyester, and calcium carbonate powder. The asphalt mixture of the present invention is suitable for paving, particularly for road paving. <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 bitumen obtained by subjecting crude oil to atmospheric distillation equipment, vacuum distillation equipment, etc. Blown asphalt refers to asphalt obtained by heating a mixture of straight asphalt and heavy oil and then oxidizing it by blowing air into it. The asphalt is preferably selected from straight asphalt and modified asphalt, with modified asphalt being more preferred from the viewpoint of rutting resistance of asphalt pavement and straight asphalt being more preferred from the viewpoint of versatility.

[0050] (thermoplastic elastomer) Examples of the thermoplastic elastomer in the modified asphalt include styrene / butadiene block copolymers (hereinafter also referred to as "SB"), styrene / butadiene / styrene block copolymers (hereinafter also referred to as "SBS"), styrene / butadiene random copolymers (hereinafter also referred to as "SBR"), styrene / isoprene block copolymers (hereinafter also referred to as "SI"), styrene / isoprene / styrene block copolymers (hereinafter also referred to as "SIS"), styrene / isoprene random copolymers (hereinafter also referred to as "SIR"), ethylene / vinyl acetate copolymers, ethylene / acrylic acid ester copolymers, styrene / ethylene / butylene / styrene copolymers, styrene / ethylene / propylene / styrene copolymers, polyurethane-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, isobutylene / isoprene copolymers, polyisoprene, polychloroprene, synthetic rubbers other than those mentioned above, and at least one selected from natural rubber. 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 rutting resistance of the asphalt pavement, the content of thermoplastic elastomer in the 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.

[0051] <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.

[0052] <Calcium carbonate powder> The asphalt mixture of the present invention contains calcium carbonate powder. The calcium carbonate powder is a powdery material, and specific examples thereof include limestone powder. The average particle size of the calcium carbonate powder is preferably 0.001 mm or more from the viewpoint of adhesion of asphalt mortar, and from the same viewpoint, it is preferably less than 0.075 mm, more preferably 0.05 mm or less, even more preferably 0.03 mm or less, and even more preferably 0.02 mm or less. The average particle size of the calcium carbonate powder can be measured with a laser diffraction particle size distribution analyzer. Here, the average particle size is the average particle size at 50% cumulative volume (D 50 ) means

[0053] The content of calcium carbonate powder in the total of 100% by mass of aggregate and calcium carbonate powder is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of maintaining mortar between the coarse aggregates, and is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, from the viewpoint of maintaining a certain strength.

[0054] 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.

[0055] 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.

[0056] The porous asphalt can be suitably used for drainage pavement.

[0057] From the viewpoint of rutting resistance, 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.

[0058] 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 polyester. 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.

[0059] From the viewpoint of the rutting resistance of the asphalt pavement, the asphalt content in the asphalt mixture is preferably 1% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and preferably 40% by mass or less, more preferably 35% by mass or less, even more preferably 30% by mass or less.

[0060] The asphalt mixture may further contain other components as required.

[0061] [Asphalt mixture manufacturing method] The asphalt mixture of the present invention can be obtained by blending asphalt, heated aggregate, calcium carbonate powder, and the polyester. The method for producing an asphalt mixture of the present invention includes a step of mixing asphalt, heated aggregate, calcium carbonate powder, and polyester 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 asphalt to heated aggregate and calcium carbonate powder, and then adding and mixing polyester; (ii) Adding and mixing asphalt and polyester simultaneously to the heated aggregate and calcium carbonate powder; or (iii) The heated aggregate and calcium carbonate powder are mixed with the pre-heated mixture of asphalt and polyester.

[0062] 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 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 asphalt.

[0063] The mixing temperature of the aggregate with 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 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 asphalt. The mixing time for the aggregate, calcium carbonate powder, asphalt, and polyester is not particularly limited, but is preferably 20 seconds or more, more preferably 40 seconds or more, and even more preferably 1 minute or more. The upper limit of the time is not particularly limited, but is preferably about 30 minutes. The asphalt mixture of the present invention allows for a shorter mixing time.

[0064] 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.

[0065] [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 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 rut resistance.

[0066] From the viewpoint of rutting resistance, 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]

[0067] 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.

[0068] [Softening point of polyester (Ts)] 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.

[0069] [Polyester glass transition temperature (Tg)] Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.01-0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and cooled to 0°C at a rate of 10°C / min. Measurements were then performed while the temperature was increased to 150°C at a rate of 10°C / min. The glass transition temperature was determined as the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0070] [Acid value and hydroxyl value of polyester] The acid value and hydroxyl value of the polyester were measured according to the method of JIS K0070: 1992. However, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070: 1992 to a mixed solvent of acetone and toluene (acetone:toluene = 1:1 (volume ratio)).

[0071] [Amine value of polyester] The amine value of the polyester was measured based on the method of JIS K2501:2003.

[0072] Production Examples 1, 2 and 6 (Polyesters A1, A2 and A6) The raw material monomers listed in Table 1, except for 3-(dimethylamino)-1-propanol, were placed in a 10-L four-neck flask equipped with a thermometer, stainless steel stirrer, dehydration tube, nitrogen inlet tube, and thermocouple. The amounts of tin(II) di(2-ethylhexanoate) and gallic acid listed in Table 1 were added under a nitrogen atmosphere, and the mixture was heated to 235°C over 3 hours in a mantle heater. After holding at 235°C for 5 hours, the reaction was carried out under reduced pressure at 8.0 kPa for 1 hour. The mixture was then cooled to 140°C, and 3-(dimethylamino)-1-propanol was added. The mixture was heated to 200°C over 2 hours, held at 200°C for 1 hour, and then reacted under reduced pressure at 8.3 kPa until the listed softening points were reached, yielding polyesters A1, A2, and A6. The results are shown in Table 1.

[0073] Manufacturing Example 3 (Polyester A3) The raw material monomers listed in Table 1, except for N,N-dimethylglycine, were placed in a 10-L four-neck flask equipped with a thermometer, stainless steel stirrer, dehydration tube, nitrogen inlet tube, and thermocouple. Under a nitrogen atmosphere, the amounts of tin(II) di(2-ethylhexanoate) and gallic acid listed in Table 2 were added, and the mixture was heated to 235°C over 3 hours in a mantle heater. After holding at 235°C for 5 hours, the reaction was carried out under reduced pressure at 8.0 kPa for 1 hour. The mixture was then cooled to 140°C, and N,N-dimethylglycine was added. The mixture was heated to 200°C over 2 hours, held at 200°C for 1 hour, and then reacted under reduced pressure at 8.3 kPa until the softening point was reached, yielding Polyester A3. The results are shown in Table 1.

[0074] Production Examples 4 and 5 (Polyesters A4 and A5) The raw material monomers listed in Table 1, bisphenol A PO adduct, terephthalic acid, and PET (polyethylene terephthalate), were placed in a 10 L four-neck flask equipped with a thermometer, stainless steel stirrer, dehydration tube, downflow condenser, and nitrogen inlet tube. The amounts of tin(II) di(2-ethylhexanoate) and gallic acid listed in Table 1 were added under a nitrogen atmosphere. The mixture was heated to 235°C over 3 hours in a mantle heater, held at 235°C for 5 hours, and then reacted under reduced pressure at 8.0 kPa for 1 hour. After visually confirming the disappearance of PET particles from the reaction mixture, the mixture was cooled to 180°C and alkenylsuccinic anhydride was added. The mixture was heated to 210°C over 2 hours, held at 210°C for 1 hour, and then reacted under reduced pressure at 8.3 kPa. The mixture was then cooled to 140°C and 3-(dimethylamino)-1-propanol was added. The temperature was raised to 200°C over 2 hours, and then the mixture was maintained at 200°C for 1 hour, after which the reaction was continued under reduced pressure of 8.3 kPa until the softening point was reached, yielding polyesters A4 and A5. The results are shown in Table 1. The alkenyl succinic anhydride used was dodecenyl succinic anhydride (average molecular weight 256).

[0075] Production Example 7 (Polyester C1) The raw material monomers shown in Table 1 were placed in a 10-L four-neck flask equipped with a thermometer, stainless steel stirrer, dehydration tube, nitrogen inlet tube, and thermocouple. Tin(II) di(2-ethylhexanoate) and gallic acid were added under a nitrogen atmosphere, and the temperature was raised to 235°C. The reaction was then continued at 235°C for 8 hours, and then further continued at 235°C and a reduced pressure of 8.3 kPa until the softening point indicated, yielding polyester C1. The results are shown in Table 1.

[0076] [Table 1]

[0077] 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. Next, 0.82 kg of modified type II asphalt (Epochphalt D, manufactured by Nisshin Seiki Co., Ltd.) heated to 180°C was added and mixed in the asphalt mixer for 60 seconds. 164.6 kg of Polyester A1 obtained in Production Example 1 was then added and mixed for an additional 20 seconds to obtain asphalt mixture AS-1. The resulting asphalt mixture AS-1 was stored at 180°C for 1 hour, after which approximately 10.7 kg of the asphalt mixture was filled into a metal formwork (300 x 300 x 50 mm) and compacted at 150°C, 0.44 kPa load, and 25 revolutions using an air-operated roller compactor (manufactured by Iwata Kogyosho Co., Ltd.) to produce a wheel tracking specimen (T-1). Durability evaluation was performed as follows.

[0078] <Amount of rutting> An asphalt specimen was immersed in hot water set to 60°C in a 60°C thermostatic chamber for one hour, and a water-immersion wheel tracking test was performed using a wheel tracking tester (Iwata Kogyosho Co., Ltd., "AI-1100-S") under the following conditions: temperature 60°C, running speed 15 times / min, load 140 kgf, and steel wheels (47 mm wide). The amount of rutting was measured by measuring the displacement of the specimen after 1,200 wheel cycles. Other measurement conditions followed the "B003 Wheel Tracking Test" described in the "Pavement Survey and Testing Methods Handbook" published by the Japan Road Association. The results are shown in Table 2.

[0079] <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 19.0 mm: 100% by mass Sieve size 9.50mm: 80.1% by mass Sieve size 4.75mm: 59.4% by mass Sieve size 2.36mm: 43.4% by mass Sieve size 1.18mm: 29.1% by mass Sieve size 600 μm: 18.9 mass% Sieve size 300 μm: 11.7 mass% Sieve size 150 μm: 7.6 mass%

[0080] Examples 2 to 6 Asphalt specimens were prepared in the same manner as in Example 1, except that the composition was changed to that shown in Table 2. The results are shown in Table 2.

[0081] Example 7 Except for changing the mixing time after adding Polyester A1 to 60 seconds, an asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Example 1. The results are shown in Table 2.

[0082] Example 8 Except for changing the mixing time after adding Polyester A5 to 60 seconds, an asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Example 5. The results are shown in Table 2.

[0083] Comparative Example 1 Except for not adding Polyester A1 and mixing for an additional 20 seconds after 60 seconds, an asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Example 1. The results are shown in Table 2.

[0084] Comparative Example 2 Asphalt specimens were prepared and the amount of rutting was measured in the same manner as in Example 1, except that the blending was changed to that shown in Table 2. The results are shown in Table 2.

[0085] Comparative Example 3 Except for adding 164.6 g of Polyester C1 and 7.63 g of 3-(dimethylamino)-1-propanol instead of Polyester A1, an asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Example 1. The results are shown in Table 2.

[0086] Comparative Example 4 An asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Example 1, except that 164.6 g of Polyester C1 and 8.23 ​​g of an effective amount of dispersant "Solsperse 11200" (manufactured by Lubrizol, 50% by mass solution) were added instead of Polyester A1. The results are shown in Table 2.

[0087] Comparative Example 5 Except for not adding Polyester A1 and mixing for another 60 seconds after 60 seconds, an asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Example 1. The results are shown in Table 2.

[0088] Comparative Example 6 Except for changing the mixing time after adding Polyester C1 to 60 seconds, an asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Comparative Example 2. The results are shown in Table 2.

[0089] Comparative Example 7 Except for changing the mixing time after adding Polyester C1 and the dispersant to 60 seconds, an asphalt specimen was prepared and the amount of rutting was measured in the same manner as in Comparative Example 4. The results are shown in Table 2.

[0090] [Table 2]

[0091] The results in Table 2 show that in Examples 1 to 6, in which specific asphalt modifiers were added, pavement surfaces with excellent rutting resistance could be formed even with a short mixing time for the asphalt mixture. Even when compared with cases in which the mixing time was long (Examples 7 and 8), durability was similarly excellent. In contrast, in Comparative Example 2, in which a polyester other than the present invention was used, Comparative Example 3, in which an amino alcohol was used in combination with a polyester other than the present invention, and Comparative Example 4, in which a dispersant was used in combination with a polyester other than the present invention, the rutting resistance was poor when the mixing time was short. When the mixing time was long (Comparative Examples 6 and 7), the desired durability was achieved.

Claims

1. An asphalt modifier comprising a polyester which contains structural units derived from an alcohol component and structural units derived from a carboxylic acid component and has an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less.

2. The asphalt modifier according to claim 1 , wherein the alcohol component comprises an amino alcohol or the carboxylic acid component comprises an amino carboxylic acid.

3. The asphalt modifier according to claim 2, wherein the amino alcohol is an amino alcohol having a dialkylamino group, or the amino carboxylic acid is an amino carboxylic acid having a dialkylamino group.

4. The asphalt modifier according to claim 2 or 3, wherein the amino alcohol is an amino alcohol represented by the following formula (1a), or the amino carboxylic acid is an amino carboxylic acid represented by the following formula (1b): 【Chemical 1】 【Chemistry 2】 [In the formula, R 11 and R 12 are independently a hydrocarbon group having 1 to 20 carbon atoms; X is a hydrocarbon group having 2 to 20 carbon atoms; and Y is a hydrocarbon group having 1 to 20 carbon atoms.

5. The asphalt modifier according to any one of claims 2 to 4, wherein the content of amino alcohol in the alcohol component is 2 mol% or more and 20 mol% or less.

6. The asphalt modifier according to any one of claims 1 to 5, wherein the alcohol component comprises an alkylene oxide adduct of bisphenol A.

7. 7. The asphalt modifier according to claim 6, wherein the content of the alkylene oxide adduct of bisphenol A is 20 mol% or more based on 100 mol% of the alcohol component.

8. The asphalt modifier according to any one of claims 1 to 7, wherein the carboxylic acid component contains a total of 40 mol% or more of one or more selected from terephthalic acid and isophthalic acid.

9. An asphalt mixture comprising asphalt, aggregate, polyester, and calcium carbonate powder, The polyester contains structural units derived from alcohol components and structural units derived from carboxylic acid components, and the asphalt mixture has an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less.

10. The asphalt mixture according to claim 9, wherein the content of the calcium carbonate is 1% by mass or more and 30% by mass or less, based on a total of 100% by mass of the aggregate and calcium carbonate.

11. A method for producing an asphalt mixture, comprising the step of mixing asphalt, heated aggregate, calcium carbonate powder, and the polyester, wherein the polyester contains a structural unit derived from an alcohol component and a structural unit derived from a carboxylic acid component, and has an amine value of 5 mgKOH / g or more and 100 mgKOH / g or less.

12. A road paving method, comprising the step of applying the asphalt mixture according to claim 9 or 10 to a road to form an asphalt pavement layer.

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