Asphalt Composition

Abstract

To provide an asphalt composition that has excellent storage stability and that can prevent rutting on a paved surface after construction, an asphalt mixture, a method for producing the same, and a pavement and a road pavement method.SOLUTION: An asphalt composition contains asphalt, polyester and a hydrocarbon solvent.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] 2. Description of the Related Art Asphalt pavement using asphalt mixtures 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 has a road surface formed from an asphalt mixture in which aggregate is bound with asphalt, so the paved road has good hardness and durability. However, asphalt pavement surfaces develop ruts and cracks over time, making it necessary to repair the pavement, which increases maintenance costs and has a significant impact on automobile traffic.

[0003] Patent Document 1 discloses an asphalt composition containing asphalt, a polyester resin, and a dispersant, as an asphalt composition having excellent storage stability at high temperatures and high dry strength. Patent Document 2 discloses an additive for recycled asphalt obtained by mixing 40% by mass to 95% by mass of pyrolysis by-product oil, which is a by-product produced when petroleum hydrocarbons are pyrolyzed to produce olefins, with 5% by mass to 60% by mass of liquid polystyrene obtained by dissolving gel-like or cake-like polystyrene in an aromatic hydrocarbon solvent having a boiling point of 100°C to 220°C, with the aim of providing a low-cost additive for recycled asphalt that restores the physical properties of deteriorated asphalt components to the same extent as conventional additives for recycled asphalt and has high fluidity at room temperature. Patent Document 3 discloses an asphalt composition that provides excellent durability of pavement surfaces after construction, the asphalt composition containing asphalt, a thermoplastic elastomer, and a polyester, the polyester having a softening point of 90°C or higher and 140°C or lower and a glass transition point of 40°C or higher and 80°C or lower, and the ratio of the polyester being 1 part by mass or higher and 17 parts by mass or lower per 100 parts by mass of asphalt. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-030996 A [Patent Document 2] JP 2008-095062 A [Patent Document 3] JP 2019-019325 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the prior art, it was difficult to simultaneously suppress rutting and ensure the storage stability of the asphalt composition at high temperatures. For example, the techniques of Patent Documents 2 and 3 can suppress rutting, but have problems with the storage stability of asphalt at high temperatures. In Patent Document 1, the storage stability is improved by adding a dispersant, but there is still room for improvement in suppressing rutting. The problem that the present invention aims to solve is to provide an asphalt composition, an asphalt mixture and a manufacturing method thereof, and a pavement and road paving method that are excellent in storage stability and can suppress rutting on the pavement surface after construction. [Means for solving the problem]

[0006] The present invention relates to the following [1] to [5]. [1] An asphalt composition comprising asphalt, a polyester and a hydrocarbon solvent. [2] An asphalt mixture comprising the asphalt composition according to [1] above and aggregate. [3] A pavement formed by paving with the asphalt mixture described in [2] above. [4] A method for paving a road, comprising the step of applying the asphalt mixture according to [2] above to a road to form an asphalt pavement layer. [5] A method for producing an asphalt mixture, comprising the step of mixing heated aggregate, asphalt, polyester, and a hydrocarbon solvent. Effect of the Invention

[0007] According to the present invention, it is possible to provide an asphalt composition, an asphalt mixture and a method for producing the same, and a method for paving a pavement and a road, which have excellent storage stability and can suppress rutting on a pavement surface after construction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Asphalt composition] The asphalt composition of the present invention contains asphalt, polyester, and a hydrocarbon solvent. The asphalt composition of the present invention has excellent storage stability and can significantly reduce rutting on the pavement surface after construction compared to conventional techniques. Furthermore, by applying this technology, it is possible to provide an asphalt mixture and a method for producing the same, as well as a pavement and a method for paving roads.

[0009] Although the detailed mechanism by which the effects of the present invention are obtained is unclear, part of it is thought to be as follows. It is presumed that the polyester interacts with asphaltene to form a high-strength polyester-asphaltene complex, which in turn suppresses rutting on the pavement surface after construction. On the other hand, in asphalt, asphaltene is surrounded by resin, and the resin inhibits the interaction between polyester and asphaltene. Here, hydrocarbon solvents such as dodecane have a high affinity with resin and a slightly low affinity with asphaltene. Therefore, it is presumed that the addition of a hydrocarbon solvent promotes the desorption of resin from asphaltene, which in turn promotes the interaction between asphaltene and polyester, and as a result, it is possible to further suppress rutting on the pavement surface after construction. Furthermore, it is presumed that the incorporation of a hydrocarbon solvent makes the polyester more compatible with the asphalt components, the polyester particles are finely dispersed in the asphalt, and aggregation of the polyester is suppressed, resulting in improved storage stability of the asphalt composition.

[0010] "Rutting" refers to the flow of the asphalt layer that forms the pavement surface during high temperatures such as summer, resulting in continuous unevenness in the longitudinal direction of the roadway. Rutting is correlated with the plastic flow resistance of the asphalt composition that is the binder of asphalt pavement, and according to the SUPERPAVE binder standard (Japan Road Association, Pavement Testing Method Handbook Supplement, 1996), the G of the asphalt composition (binder) * / sinδ, where G * represents the complex modulus of elasticity, and G * and sin δ are measured with a rheometer. G * The larger the value of / sin δ, the greater the plastic flow resistance, and therefore it is evaluated that the asphalt composition can provide an asphalt pavement with excellent rut resistance.

[0011] The definitions of various terms used in this specification are given 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 obtained by removing a hydrogen atom from a hydroxyl group of an alcohol component, and a "structural unit derived from a carboxylic acid component" means a structure obtained by removing a hydroxyl group 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 a reaction to generate 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 a carboxylic acid, the number of carbon atoms of the alkyl group that is the alcohol residue of the ester is not included in the number of carbon atoms of the carboxylic acid compound.

[0012] <Asphalt> The asphalt composition of the present invention contains asphalt. As the asphalt, various kinds of asphalt can be used. For example, in addition to straight asphalt, which is petroleum asphalt for paving, modified asphalt can be mentioned. Modified asphalt can be blown asphalt; asphalt modified with polymeric materials such as thermoplastic elastomers and thermoplastic resins. Straight asphalt is a residual bituminous material obtained by subjecting crude oil to atmospheric distillation equipment, vacuum distillation equipment, etc. Blown asphalt means asphalt obtained by heating a mixture of straight asphalt and heavy oil, and then blowing air into it to oxidize it. Modified asphalt is preferable from the viewpoint of rut resistance, and straight asphalt is preferable from the viewpoint of versatility.

[0013] (Thermoplastic elastomer) From the viewpoint of rut resistance, the asphalt composition preferably contains a thermoplastic elastomer. The asphalt and the thermoplastic elastomer are preferably used as a binder mixture, which is a mixture of these. Examples of the binder mixture include straight asphalt (modified asphalt) modified with a thermoplastic elastomer.

[0014] Examples of the thermoplastic elastomer include at least one selected from the group consisting of styrene / butadiene block copolymer (hereinafter, also referred to as "SB"), styrene / butadiene / styrene block copolymer (hereinafter, also referred to as "SBS"), styrene / butadiene random copolymer (hereinafter, also referred to as "SBR"), styrene / isoprene block copolymer (hereinafter, also referred to as "SI"), styrene / isoprene / styrene block copolymer (hereinafter, also referred to as "SIS"), styrene / isoprene random copolymer (hereinafter, also referred to as "SIR"), ethylene / vinyl acetate copolymer, and ethylene / acrylic acid ester copolymer. An example of a commercially available ethylene / acrylic acid ester copolymer is "Elvaroy" (manufactured by DuPont).

[0015] Among these thermoplastic elastomers, from the viewpoint of improving rut resistance, at least one selected from the group consisting of styrene / butadiene block copolymers, styrene / butadiene / styrene block copolymers, styrene / butadiene random copolymers, styrene / isoprene block copolymers, styrene / isoprene / styrene block copolymers, and styrene / isoprene random copolymers is preferred, and at least one selected from the group consisting of styrene / butadiene random copolymers and styrene / butadiene / styrene block copolymers is more preferred.

[0016] From the viewpoint of improving rut resistance, the content of the thermoplastic elastomer in the asphalt composition is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, even more preferably 1 mass% or more, and even more preferably 2 mass% or more, based on 100 mass% of the asphalt composition, and is preferably 30 mass% or less, more preferably 20 mass% or less, even more preferably 10 mass% or less, and even more preferably 5 mass% or less.

[0017] In the asphalt composition, the content of the thermoplastic elastomer is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, even more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, per 100 parts by mass of asphalt, from the viewpoint of improving rut resistance, and is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less.

[0018] In the asphalt composition of the present invention, the content of asphalt is preferably 60% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 70% by mass or more, from the viewpoint of rut resistance and exhibiting asphalt performance, and from the viewpoint of containing polyester and hydrocarbon solvent and improving rut resistance, the content of asphalt is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0019] <Polyester> The asphalt composition of the present invention contains a polyester. From the viewpoint of improving the rut resistance of the pavement surface after construction, the polyester preferably contains constitutional units derived from an alcohol component containing 60 mol % or more of an alkylene oxide adduct of bisphenol A and constitutional units derived from a carboxylic acid component.

[0020] (Alcohol content) Examples of the alcohol component include diols and polyhydric alcohols having three or more valences. Examples of the diols include aliphatic diols and aromatic diols. These alcohol components can be used alone or in combination of two or more. From the viewpoint of obtaining excellent rut resistance, the alcohol component preferably contains an alkylene oxide adduct of bisphenol A, and more preferably contains an alkylene oxide adduct of bisphenol A represented by formula (I). [ka] [In the formula, OR 1 and R 1O is an 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.

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

[0022] From the viewpoint of improving melt dispersibility in asphalt and obtaining excellent rut resistance, the content of the alkylene oxide adduct of bisphenol A is preferably 60 mol % or more, more preferably 75 mol % or more, and even more preferably 90 mol % or more, and is 100 mol % or less, based on 100 mol % of the alcohol component.

[0023] Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,10-decanediol, and 1,12-dodecanediol. The polyhydric alcohol having a valence of three or more is, for example, a trihydric alcohol. An example of the polyhydric alcohol having a valence of three or more is glycerin.

[0024] (Carboxylic acid component) Examples of the carboxylic acid component include an aliphatic dicarboxylic acid compound, an aromatic dicarboxylic acid compound, and a polyvalent carboxylic acid compound having a valence of 3 to 6. These carboxylic acid components can be used alone or in combination of two or more kinds.

[0025] From the viewpoint of improving rut resistance, the carbon number of the main chain of the aliphatic dicarboxylic acid compound is preferably 3 or more, more preferably 4 or more, and is preferably 10 or less, more preferably 8 or less. Examples of the aliphatic dicarboxylic acid compound include fumaric acid, maleic acid, oxalic acid, malonic acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, and succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms. Examples of the substituted succinic acid include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Among the above aliphatic dicarboxylic acid compounds, at least one selected from the group consisting of fumaric acid, maleic acid, and adipic acid is preferred, and adipic acid is more preferred.

[0026] Examples of the aromatic dicarboxylic acid compound include phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. Among the above aromatic dicarboxylic acid compounds, isophthalic acid and terephthalic acid are preferred from the viewpoint of obtaining rut resistance, and terephthalic acid is more preferred.

[0027] The polycarboxylic acid compound having a valence of 3 to 6 is preferably a tricarboxylic acid. Examples of the polycarboxylic acid compound having a valence of 3 to 6 include trimellitic acid, 2,5,7-naphthalene tricarboxylic acid, and pyromellitic acid. When the polycarboxylic acid compound is contained, from the viewpoint of adjusting physical properties, the alcohol component may appropriately contain a monohydric alcohol, and the carboxylic acid component may appropriately contain a monocarboxylic acid compound.

[0028] From the viewpoint of increasing the flexibility of the polyester and improving the rut resistance, the content of the aliphatic dicarboxylic acid compound is preferably 1 mol % or more, more preferably 5 mol % or more, and even more preferably 10 mol % or more, based on 100 mol % of the carboxylic acid component, and is preferably 40 mol % or less, more preferably 25 mol % or less.

[0029] From the viewpoint of improving melt dispersibility in asphalt and obtaining excellent rut resistance, the content of the aromatic dicarboxylic acid compound is preferably 60 mol% or more, more preferably 75 mol% or more, and preferably 99 mol% or less, more preferably 95 mol% or less, and even more preferably 90 mol% or less, based on 100 mol% of the carboxylic acid component.

[0030] (Molar ratio of structural units derived from carboxylic acid components to structural units derived from alcohol components) From the viewpoint of adjusting the acid value, the molar ratio of the constituent units derived from the carboxylic acid component to the constituent units derived from the alcohol component [carboxylic acid component / alcohol component] is preferably 0.7 or more, more preferably 0.8 or more, and is preferably 1.5 or less, more preferably 1.3 or less, and even more preferably 1.1 or less.

[0031] The polyester of the present invention may be modified to such an extent that its properties are not substantially impaired.Specific examples of modified polyesters include polyesters grafted or blocked with phenol, urethane, epoxy, or the like by the methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc.Preferred modified polyesters include urethane-modified polyesters obtained by urethane-extending polyesters with a polyisocyanate compound.

[0032] (Physical properties of polyester) From the viewpoint of obtaining rut resistance, the softening point of the polyester 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 125°C or lower, even more preferably 120°C or lower, even more preferably 115°C or lower.

[0033] From the viewpoint of promoting adsorption to aggregate and improving rut resistance, the acid value of the polyester is preferably 2 mgKOH / g or more, more preferably 3 mgKOH / g or more, and even more preferably 4 mgKOH / g or more, and from the viewpoint of improving the water resistance of the pavement surface, it is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and even more preferably 18 mgKOH / g or less.

[0034] From the viewpoint of improving rut resistance, the hydroxyl value of the polyester is preferably 1 mgKOH / g or more, more preferably 2 mgKOH / g or more, even more preferably 5 mgKOH / g or more, even more preferably 10 mgKOH / g or more, and is preferably 70 mgKOH / g or less, more preferably 50 mgKOH / g or less, even more preferably 30 mgKOH / g or less, even more preferably 25 mgKOH / g or less.

[0035] From the viewpoint of obtaining rut resistance and improving flow resistance at high temperatures, the glass transition point of the polyester is preferably 40°C or higher, more preferably 45°C or higher, and is preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower.

[0036] The softening point, acid value, hydroxyl value and glass transition point can be measured by the methods described in the Examples. The softening point, acid value, hydroxyl value and glass transition point can be adjusted by the raw material monomer composition, molecular weight, catalyst amount or reaction conditions.

[0037] (Tin(II) compounds without Sn-C bonds) One embodiment of the polyester of the present invention contains a tin(II) compound having no Sn-C bond, such as tin(II) di(2-ethylhexanoate). The tin(II) compound having no Sn-C bond is derived from a polycondensation reaction in the production of polyester. The content of the tin(II) compound having no Sn-C bond is preferably 0.01 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 0.6 parts by mass or less, based on 100 parts by mass of the polycondensate of the above-mentioned alcohol component and carboxylic acid component.

[0038] (Production method of polyester) The method for producing the polyester is not particularly limited, but the polyester can be produced, for example, by polycondensing the above-mentioned alcohol component and carboxylic acid component. 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 reactivity.

[0039] In the polycondensation reaction, a tin(II) compound not having a Sn-C bond, such as tin(II) di(2-ethylhexanoate), may be used as an esterification catalyst, preferably in an amount of 0.01 part by mass or more, 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, from the viewpoint of rut resistance. In the polycondensation reaction, in addition to the esterification catalyst, from the viewpoint of rut resistance, a pyrogallol compound such as gallic acid may be used as a co-catalyst, preferably in an amount of 0.001 part by mass or more, more preferably 0.005 part by mass or more, even more preferably 0.01 part by mass or more, and preferably 0.15 part by mass or less, more preferably 0.10 part by mass or less, and even more preferably 0.05 part by mass or less, per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0040] (Polyester content) In the asphalt composition of the present invention, the content of the polyester is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of asphalt from the viewpoint of improving rut resistance, and from the viewpoint of storage stability, it is preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 20 parts by mass or less.

[0041] <Hydrocarbon solvent> The asphalt composition of the present invention contains a hydrocarbon solvent. The hydrocarbon solvent desorbs the resin adsorbed to asphaltene in the asphalt, increasing the opportunities for interaction between the polyester and asphaltene, thereby further improving rut resistance, and also improves the compatibility of the polyester with asphalt components, thereby allowing the polyester to be finely dispersed in the asphalt, which is believed to improve the storage stability of the asphalt composition.

[0042] In the above Patent Document 1, polymer dispersants, polyoxyethylene alkylamines, alkanolamines, and other surfactants are used as dispersants that dissolve in asphalt and have affinity with polyesters. When these dispersants are used, polyesters can be dispersed in asphalt to improve the storage stability of the asphalt composition. However, these dispersants have little effect on rut resistance, and only polyesters contribute to rut resistance. In contrast, as mentioned above, a hydrocarbon solvent such as dodecane has a high affinity with resins but a slightly lower affinity with asphaltene. Therefore, the incorporation of a hydrocarbon solvent promotes the desorption of resins from asphaltene, which in turn promotes the interaction between asphaltene and polyester, and as a result, the synergistic effect of polyester and hydrocarbon solvent can further suppress rutting on the pavement surface after construction.

[0043] The hydrocarbon solvent used in the present invention is preferably at least one selected from the group consisting of aliphatic hydrocarbons having 8 to 16 carbon atoms and aromatic hydrocarbons having 8 to 16 carbon atoms, more preferably at least one selected from the group consisting of linear aliphatic hydrocarbons having 8 to 16 carbon atoms, cyclic aliphatic hydrocarbons having 8 to 16 carbon atoms and aromatic hydrocarbons having 8 to 16 carbon atoms, and even more preferably at least one selected from the group consisting of linear aliphatic hydrocarbons having 10 to 12 carbon atoms and cyclic aliphatic hydrocarbons having 10 to 12 carbon atoms.

[0044] The boiling point of the hydrocarbon solvent is desirably higher than the softening point of the polyester. When producing an asphalt mixture, the mixture is stirred and mixed at a temperature equal to or higher than the softening point of the polyester. If the boiling point of the hydrocarbon solvent is lower than the softening point of the polyester, the hydrocarbon solvent will volatilize during stirring and mixing. Therefore, the carbon number of the hydrocarbon solvent is preferably 8 or more, more preferably 10 or more, since the boiling point is higher than the softening point of the polyester. On the other hand, a high boiling point hydrocarbon solvent is difficult to mix with asphalt even when heated, so the carbon number of the hydrocarbon solvent is preferably 16 or less, more preferably 12 or less, from the viewpoint of affinity with asphalt. The boiling point of the hydrocarbon solvent is preferably equal to or higher than the softening point of the polyester, and is preferably 300° C. or lower.

[0045] Specific examples of the hydrocarbon solvent include linear aliphatic hydrocarbons such as octane, nonane, decane, and dodecane, branched aliphatic hydrocarbons such as squalene and squalane, cyclic aliphatic hydrocarbons such as ethylcyclohexane, decalin, and methyldecalin, and aromatic hydrocarbons such as toluene, tetralin, and 1-methylnaphthalene. Examples of commercially available hydrocarbon mixtures include kerosene and diesel.

[0046] (Hydrocarbon solvent content) In the asphalt composition of the present invention, from the viewpoints of rut resistance and storage stability, the content of the hydrocarbon solvent is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 5 parts by mass or more, even more preferably 8 parts by mass or more, per 100 parts by mass of asphalt, and is preferably 25 parts by mass or less, more preferably 20 parts by mass or less, even more preferably 15 parts by mass or less, even more preferably 12 parts by mass or less.

[0047] [Method of producing asphalt composition] The method for producing the asphalt composition of the present invention preferably includes a step of mixing asphalt, a polyester, and a hydrocarbon solvent.

[0048] The asphalt composition can be obtained by heating and melting the asphalt, adding the polyester and the hydrocarbon solvent, and stirring and mixing the components until they are uniformly dispersed in a commonly used mixer. Commonly used mixers include homomixers, dissolvers, paddle mixers, ribbon mixers, screw mixers, planetary mixers, vacuum countercurrent mixers, roll mills, twin-screw extruders, etc.

[0049] The mixing temperature of the asphalt, polyester and hydrocarbon solvent 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 viewpoints of uniformly dispersing the polyester and hydrocarbon solvent in the asphalt and of rut resistance and storage stability, 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.

[0050] Furthermore, the mixing time of the asphalt, polyester, and hydrocarbon solvent is, from the viewpoint of efficiently dispersing the polyester and hydrocarbon solvent uniformly in the asphalt and of rut resistance and storage stability, preferably 0.1 hour or more, more preferably 0.5 hour or more, even more preferably 1.0 hour or more, and even more preferably 1.5 hour or more, and is preferably 10 hours or less, more preferably 7 hours or less, even more preferably 5 hours or less, and even more preferably 3 hours or less. The preferred contents of polyester and hydrocarbon solvent relative to asphalt are as described above.

[0051] [Asphalt mixture] The asphalt composition of the present invention is a binder composition, and is used for paving after adding aggregate to the asphalt composition to form an asphalt mixture. That is, the asphalt composition of the present invention is suitable for paving, and is particularly suitable for road paving. The asphalt mixture according to the embodiment of the present invention contains the above-mentioned asphalt composition and aggregate. That is, the asphalt mixture contains asphalt, polyester, a hydrocarbon solvent, and aggregate, and preferably contains asphalt, a thermoplastic elastomer, polyester, a hydrocarbon solvent, and aggregate.

[0052] The aggregate may be selected from any of crushed stone, boulders, gravel, sand, recycled aggregate, ceramics, and the like. As the aggregate, either coarse aggregate with a particle size of 2.36 mm or more or fine aggregate with a particle size of less than 2.36 mm can be used. Examples of coarse aggregate include No. 7 crushed stone with a particle size range of 2.36 mm or more and less than 4.75 mm, No. 6 crushed stone with a particle size range of 4.75 mm or more and less than 13.2 mm, No. 5 crushed stone with a particle size range of 13.2 mm or more and less than 19 mm, and No. 4 crushed stone with a particle size range of 19 mm or more and less than 31.5 mm. The fine aggregate is preferably one having 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 the value specified in JIS A5001:1995. Among these, a combination of coarse aggregate and fine aggregate is preferable.

[0053] The fine aggregate may contain a filler (such as sand) having a particle size of less than 0.075 mm. Examples of the filler include sand, fly ash, calcium carbonate, hydrated lime, etc. Among these, calcium carbonate is preferred from the viewpoint of rut resistance.

[0054] The average particle size of the filler is preferably 0.001 mm or more from the viewpoint of rut resistance, and from the same viewpoint, is preferably 0.05 mm or less, more preferably 0.03 mm or less, and further preferably 0.02 mm or less. The average particle size of the filler can be measured by a laser diffraction particle size distribution measuring device. Here, the average particle size means the average particle size at 50% cumulative volume.

[0055] [Method of measuring average particle size of filler] The average particle size of the filler was measured using a laser diffraction particle size distribution measuring device "LA-950" (manufactured by Horiba, Ltd.) under the conditions shown below. Measurement method: Flow method Dispersion medium: Ethanol Sample preparation: 2mg / 100mL Dispersion method: Stirring, built-in ultrasonic 1 minute

[0056] From the viewpoint of rut resistance, 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. The content of the aggregate, per 100 parts by mass of the asphalt composition, is preferably 1,000 parts by mass or more, more preferably 1,200 parts by mass or more, even more preferably 1,500 parts by mass or more, and is preferably 3,000 parts by mass or less, more preferably 2,500 parts by mass or less, even more preferably 2,000 parts by mass or less.

[0057] The mixing ratio of asphalt in conventional asphalt mixtures containing aggregate and asphalt may usually be determined in accordance with the optimal amount of asphalt obtained from the "Mix Design of Asphalt Composition" described in the "Guidelines for Pavement Design and Construction" issued by the Japan Road Association. In the present invention, the above-mentioned optimum asphalt amount corresponds to the total amount of asphalt, polyester and hydrocarbon solvent. Therefore, it is usually preferable that the optimum asphalt amount is the total amount of asphalt, polyester and hydrocarbon solvent. 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 method.

[0058] [Asphalt mixture manufacturing method] The method for producing an asphalt mixture of the present invention includes a step of mixing heated aggregate, asphalt, a polyester, and a hydrocarbon solvent, and preferably includes a step of mixing heated aggregate, asphalt, a thermoplastic elastomer, a polyester, and a hydrocarbon solvent.

[0059] Specific methods for producing asphalt mixtures include conventional methods for producing asphalt mixtures called the plant mix method and the premix method. All of these methods involve adding asphalt (and thermoplastic elastomer if necessary) to heated aggregate. Examples of the addition method include the premix method in which asphalt (and thermoplastic elastomer if necessary), polyester, and a hydrocarbon solvent are dissolved in advance, or the plant mix method in which modified asphalt in which a thermoplastic elastomer is dissolved in asphalt is added to aggregate, and then polyester and a hydrocarbon solvent are added. Among these, the premix method is preferred from the viewpoint of rut resistance. More specifically, in the method for producing an asphalt mixture, in the mixing step, preferably, (i) Adding and mixing asphalt (and thermoplastic elastomer, if necessary) to heated aggregate to obtain a mixture, then adding polyester and a hydrocarbon solvent, and mixing the mixture with the polyester and the hydrocarbon solvent; (ii) adding and mixing the asphalt (and optionally the thermoplastic elastomer), polyester and hydrocarbon solvent simultaneously to the heated aggregate; or (iii) Adding and mixing a pre-heat mixed mixture of asphalt (and optionally thermoplastic elastomer), polyester and hydrocarbon solvent to the heated aggregate. Among these, method (iii) is preferred from the viewpoint of rut resistance.

[0060] In the method (iii), the mixing temperature when the asphalt, polyester, and hydrocarbon solvent are mixed in advance is preferably a temperature higher than the softening point of the polyester from the viewpoint of durability, and is preferably 130°C or higher, more preferably 150°C or higher, even more preferably 170°C or higher, and even more preferably 180°C or higher. From the viewpoint of preventing thermal deterioration of the asphalt and suppressing the volatilization of the hydrocarbon solvent, it is preferably 220°C or lower, more preferably 200°C or lower, and even more preferably 190°C or lower. The mixing time is, for example, 10 minutes or more, preferably 30 minutes or more, more preferably 1 hour or more, and even more preferably 2 hours or more. The upper limit of the time is not particularly limited, but is, for example, about 5 hours.

[0061] The temperature of the heated aggregate in the methods (i) to (iii) is preferably higher than the softening point of the polyester from the viewpoint of durability, and is preferably 130°C or higher, more preferably 150°C or higher, even more preferably 170°C or higher, and even more preferably 180°C or higher, and from the viewpoint of preventing thermal degradation of the asphalt, is preferably 230°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower.

[0062] In the mixing step, the mixing temperature is preferably higher than the softening point of the polyester, and is preferably 130° C. or higher, more preferably 150° C. or higher, even more preferably 170° C. or higher, and even more preferably 180° C. or higher, and from the viewpoint of preventing thermal deterioration of the asphalt and suppressing volatilization of the hydrocarbon solvent, is preferably 220° C. or lower, more preferably 200° C. or lower, and even more preferably 190° C. or lower. The mixing time in the mixing step is, for example, 30 seconds or longer, preferably 1 minute or longer, more preferably 2 minutes or longer, and the upper limit of the time is not particularly limited, but is, for example, about 10 minutes.

[0063] From the viewpoint of further improving durability, the method for producing an asphalt mixture preferably includes, after the mixing step, a step of holding the resulting mixture at a temperature higher than the softening point of the polyester or higher. In the holding step, the mixture may be further mixed, but it is sufficient that the temperature is held at or above the above-mentioned temperature. The holding temperature is preferably a temperature higher than the softening point of the polyester, and is preferably 130°C or higher, more preferably 150°C or higher, more preferably 170°C or higher, and even more preferably 180°C or higher. From the viewpoint of preventing thermal deterioration of the asphalt composition and suppressing the volatilization of the hydrocarbon solvent, it is preferably 220°C or lower, more preferably 200°C or lower, and even more preferably 190°C or lower. The holding time in the holding step is preferably 0.5 hours or more, more preferably 1 hour or more, and even more preferably 1.5 hours or more, and the upper limit of the time is not particularly limited, but is, for example, about 5 hours.

[0064] [Road paving method, pavement material] The asphalt composition of the present invention is suitable for road paving, and as described above, an asphalt mixture obtained by adding aggregate to the asphalt composition is used for road paving. The road paving 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. A pavement paved with the asphalt mixture of the present invention has strong adhesion between the aggregate and the asphalt, and can suppress rutting.

[0065] In the road paving method, the asphalt mixture may be compacted and applied in the same manner as in the case of normal asphalt mixtures using the same construction machine arrangement. 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, from the viewpoint of rut resistance, and is preferably 200°C or lower, more preferably 180°C or lower, and even more preferably 170°C or lower. EXAMPLES

[0066] Various physical properties were measured and evaluated by the following methods. In the following examples and comparative examples, parts and percentages are by weight unless otherwise specified.

[0067] (1) 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)).

[0068] (2) Softening point of polyester Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of the sample was heated at a temperature increase rate of 6°C / min, while applying a load of 1.96 MPa with the plunger, and extruding the sample from a nozzle with a diameter of 1 mm and a length of 1 mm. The plunger descent amount 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] (3) Glass transition temperature of polyester Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed into an aluminum pan, heated to 200°C, and cooled to 0°C at a rate of 10°C / min. The calorific value was then measured while heating to 150°C at a rate of 10°C / min. The glass transition point 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 apex of the peak.

[0070] Manufacturing Example 1 (Production of polyester resin (A1)) The alcohol components of the polyester shown in Table 1 and terephthalic acid were placed in a 5-liter four-neck flask equipped with a thermometer, a stainless steel stirring rod, a downflow condenser, and a nitrogen inlet tube, and 20 g of tin(II) di(2-ethylhexanoate) and 2 g of gallic acid were added in a nitrogen atmosphere. The temperature was raised to 235°C over 3 hours in a mantle heater, and after reaching 235°C, it was held for 7 hours, and then a reaction was carried out under reduced pressure at 8.0 kPa for 1 hour. After that, it was cooled to 180°C, and the remaining acid was added, and the temperature was raised to 210°C over 2 hours, and then it was held at 210°C for 1 hour, and a reaction was carried out under reduced pressure at 8.0 kPa, and the reaction was continued until the softening point shown in Table 1 was reached, to obtain polyester resin (A1).

[0071] [Table 1]

[0072] Example 1 To 100 parts of modified asphalt A (polymer modified asphalt, manufactured by Ergon Asphalt and Emulsions) preheated to 180°C, 3 parts of polyester resin A1 prepared in Production Example 1 and 10 parts of decalin (decahydronaphthalene, cis / trans mixture, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were added, and the mixture was stirred in a homomixer at a rotation speed of 3,000 r / min and an internal temperature of 180°C for 2 hours to obtain an asphalt composition.

[0073] Examples 2 to 4 An asphalt composition was obtained in the same manner as in Example 1, except that the amount of decalin was changed to the amount shown in Table 2.

[0074] Examples 5 to 8 An asphalt composition was obtained in the same manner as in Example 1, except that decalin was changed to an additive shown in Table 2.

[0075] Example 9 An asphalt composition was obtained in the same manner as in Example 1, except that in Example 1, modified asphalt A was changed to modified asphalt B (modified type II asphalt, manufactured by Toa Road Industry Co., Ltd.) and the amount of polyester resin was changed to 20 parts.

[0076] Comparative Example 1 Modified asphalt A was used.

[0077] Comparative Example 2 An asphalt composition was obtained in the same manner as in Example 1, except that the polyester resin was not blended.

[0078] Comparative Example 3 An asphalt composition was obtained in the same manner as in Example 1, except that decalin was not blended.

[0079] Comparative Example 4 An asphalt composition was obtained in the same manner as in Example 1, except that 10 parts of decalin was replaced with 0.5 parts of a polymer dispersant "Solsperse 11200" (manufactured by Lubrizol Corporation).

[0080] [evaluation] [Storage stability of asphalt composition] 50 mL of the asphalt composition was poured into a sample bottle (inner diameter 3.5 cm x height 7.8 cm) and stored in a 180°C oven for 12 hours, after which the height of the polyester precipitate in the asphalt composition was measured. The percentage of the height of the precipitate that had occurred relative to the height of the precipitate if all of the polyester in the asphalt had precipitated was calculated and used as an index of storage stability. The lower the value, the less the amount of precipitation and the better the storage stability. In Table 2, "PES" means polyester.

[0081] [Rutting resistance of pavement surface after construction] 11 kg of aggregate heated to 180°C was added to an asphalt mixer (20 L capacity, Iwata Kogyosho Co., Ltd. "AI-110-B") heated to 180°C and mixed for 60 seconds, after which 621 g (3 parts polyester) or 723 g (20 parts polyester) of asphalt previously heated and mixed at 180°C, or 603 g (0 parts polyester) of asphalt simply melted by heating, were added and mixed for 120 seconds. The mixed asphalt mixture was cured in an oven (180°C) for 2 hours, then filled into a metal formwork (300 x 300 x 50 mm) and compacted with a linear pressure of 29.4 kN / m using an air-pressure roller compactor (Iwata Kogyosho Co., Ltd.) to create a wheel tracking specimen. The created specimen was cooled at room temperature overnight, and then a rut measurement test was performed using a water-immersion wheel tracking tester (Iwata Kogyosho Co., Ltd. "AI-1100-S"). The measurement conditions were: temperature 60°C, running speed 15±1 round trips / min, wheel load 100kgf, and number of round trips 2,500. (Aggregate blend) Ieshima crushed stone (small) 52% by mass Ieshima crushed sand 10% by mass Ibi River sand 22% by mass Koga crushed sand 10% by mass Neoflow manufactured by Shimizu Kogyo Co., Ltd. 5% by mass

[0082] [Table 2]

[0083] In Comparative Example 2, in which decalin was blended with asphalt, Comparative Example 3, in which polyester was blended with asphalt, and Comparative Example 4, in which polyester and a polymer dispersant were blended with asphalt, rutting on the pavement surface after construction was suppressed compared to the asphalt of Comparative Example 1, which did not contain polyester and a hydrocarbon solvent. In contrast, in Examples 1 to 9, in which polyester and a hydrocarbon solvent were blended with asphalt, rutting could be suppressed more significantly than in Comparative Examples 2 to 4. In addition, a comparison of Comparative Examples 3 and 4 shows that when a polymer dispersant was added, polyester was dispersed in the asphalt, improving the storage stability of the asphalt composition, but the polymer dispersant did not have the effect of improving rut resistance. In contrast, in Examples 1 to 9, in which polyester and a hydrocarbon solvent were added to the asphalt, not only was the storage stability of the asphalt composition improved, but the synergistic effect of the polyester and the hydrocarbon solvent was able to further suppress rut ​​formation on the pavement surface after construction. In particular, among the examples, Examples 1, 5, and 8, which contained a hydrocarbon solvent having a carbon number of 10 to 12, were able to more significantly suppress rutting, and the storage stability of the asphalt composition was also significantly excellent.

Claims

1. The method includes mixing heated aggregate, asphalt, polyester, and a hydrocarbon solvent; The softening point of the polyester is 90° C. or higher and 140° C. or lower, The mixing temperature is higher than the softening point of the polyester, (i) adding and mixing asphalt with heated aggregate to obtain a mixture, then adding polyester and a hydrocarbon solvent, and mixing the mixture with the polyester and the hydrocarbon solvent; (ii) adding and mixing the asphalt, polyester and hydrocarbon solvent simultaneously to the heated aggregate; or (iii) A method for producing an asphalt mixture, in which a mixture of pre-heated and mixed asphalt, polyester and hydrocarbon solvent is added to and mixed with heated aggregate.

2. The temperature of the heated aggregate is 130°C or higher and 230°C or lower, and The method for producing an asphalt mixture according to claim 1, wherein the mixing temperature is 130°C or higher and 220°C or lower.

3. The method for producing an asphalt mixture according to claim 1 or 2, wherein the hydrocarbon solvent is at least one selected from the group consisting of aliphatic hydrocarbons having 8 to 16 carbon atoms and aromatic hydrocarbons having 8 to 16 carbon atoms.

4. The method for producing an asphalt mixture according to any one of claims 1 to 3, wherein the blending amount of the polyester is 0.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the asphalt.

5. The method for producing an asphalt mixture according to any one of claims 1 to 4, wherein the amount of the hydrocarbon solvent is 0.5 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the asphalt.

6. A method for producing an asphalt mixture described in any one of claims 1 to 5, wherein the asphalt is a modified asphalt containing a thermoplastic elastomer.

7. The method for producing an asphalt mixture according to claim 6, wherein the thermoplastic elastomer is at least one selected from the group consisting of styrene / butadiene block copolymers, styrene / butadiene / styrene block copolymers, styrene / butadiene random copolymers, styrene / isoprene block copolymers, styrene / isoprene / styrene block copolymers, and styrene / isoprene random copolymers.

8. The method for producing an asphalt mixture according to any one of claims 1 to 7, wherein the polyester contains a tin (II) compound that does not have a Sn-C bond.

9. The method for producing an asphalt mixture according to any one of claims 1 to 8, wherein the hydrocarbon solvent is at least one selected from the group consisting of linear aliphatic hydrocarbons having 10 to 12 carbon atoms and cyclic aliphatic hydrocarbons having 10 to 12 carbon atoms.

10. A process for producing an asphalt mixture by the method for producing an asphalt mixture according to any one of claims 1 to 9; and A method for paving a road, comprising a step of applying the asphalt mixture to a road to form an asphalt pavement layer.

11. A road paving method as described in claim 10, wherein the process of applying the asphalt mixture to a road to form an asphalt pavement layer includes compaction construction, and the compaction temperature of the asphalt mixture is 100°C or higher and 200°C or lower.

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