Method for manufacturing asphalt mixture

Abstract

To provide a method for manufacturing an asphalt mixture which can efficiently extract a water resistance improving effect of an additive, and can obtain an asphalt mixture excellent in water resistance.SOLUTION: A method for manufacturing an asphalt mixture includes a step of mixing 0.03 to 4 pts.mass of an asphalt master batch to 100 pts.mass of an aggregate at 100 to 200°C, and further adding asphalt (c) thereto and mixing the mixture, wherein the asphalt master batch contains 10 to 50 mass% of a modified hydrogenated petroleum resin (a) satisfying the following (1) to (3), and straight asphalt (b). (1) In terms of silicon atom, 0.5 to 20 mass% of a silicon element is contained, (2) a weight average molecular weight is 500 to 5,000, and (3) molecular weight distribution (Mw / Mn) is 1.1 to 3.5.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for producing an asphalt mixture. [Background technology]

[0002] In recent years, the main cause of damage to asphalt pavement has been the peeling of asphalt, which occurs when rainwater or groundwater penetrates between the asphalt and aggregate, causing the asphalt covering the surface of the aggregate to peel off. This peeling of asphalt reduces the ability of the aggregate to bond together, which can lead to damage such as cracks and potholes. In response to this asphalt peeling phenomenon, methods have been investigated that involve mixing fatty acids, such as resin acids such as dimer acid and rosin, saturated fatty acids such as stearic acid, palmitic acid, and myristic acid, and unsaturated fatty acids such as oleic acid, linoleic acid, and ricinolenic acid, into the asphalt as anti-peeling agents to suppress asphalt peeling (Patent Documents 1 and 2). Furthermore, Patent Document 3 discloses an asphalt composition containing a silane-containing compound having a cyclic structure in its molecular structure or a modified hydrogenated petroleum resin having specific values ​​for bromine number, silicon content, weight average molecular weight, and molecular weight distribution, for the purpose of providing a technology for suppressing peeling of asphalt and improving water resistance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-121320 A [Patent Document 2] JP 2015-143340 A [Patent Document 3] International Publication No. 2021 / 161672 Summary of the Invention [Problem to be solved by the invention]

[0004] Although anti-stripping agents such as resin acids and fatty acids are expensive, adding more than a certain amount of them does not provide sufficient anti-stripping effect, especially for acidic rocks such as granite. Therefore, there is a demand for technology to suppress asphalt stripping even for these rocks. In addition, the technology disclosed in Patent Document 3 requires a large amount of silane-containing compound to exhibit performance. Therefore, it is necessary to add a large amount of silane-containing compound to the asphalt mixed with aggregate, which is not efficient. In other words, when a large amount of silane-containing compound is used, not only is the cost high, but crosslinking of the silane-containing compound proceeds in the high temperature environment when mixed with aggregate, which causes a problem of impeding performance. Therefore, there has been a demand for a method for improving the water resistance of asphalt pavement by more efficiently using additives such as silane-containing compounds while suppressing unnecessary reactions such as crosslinking. Therefore, an object of the present invention is to provide a method for producing an asphalt mixture that can efficiently bring out the water resistance improving effect of an additive and obtain an asphalt mixture having excellent water resistance. [Means for solving the problem]

[0005] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using a method having a step of mixing an asphalt masterbatch containing a specific modified hydrogenated petroleum resin with aggregate.

[0006] That is, the present invention provides the following: <1> ~ <6> Regarding. <1> A method for producing an asphalt mixture, comprising the steps of: mixing 0.03 to 4 parts by mass of an asphalt master batch with 100 parts by mass of aggregate at 100 to 200°C; and further adding and mixing asphalt (c), wherein the asphalt master batch contains 10 to 50% by mass of a modified hydrogenated petroleum resin (a) that satisfies the following (1) to (3); and straight asphalt (b). (1) Contains 0.5 to 20.0 mass% silicon element calculated as silicon atom (2) Weight average molecular weight is 500 to 5,000 (3) Molecular weight distribution (Mw / Mn) is 1.1 to 3.5 <2> The softening point of the modified hydrogenated petroleum resin (a) is 60 to 150° C. <1> A method for producing the asphalt mixture described in claim 1. <3> The mass ratio [(a) / (b)] of the modified hydrogenated petroleum resin (a) to the straight asphalt (b) in the asphalt masterbatch is 10 / 90 to 50 / 50. <1> or <2> A method for producing the asphalt mixture described in claim 1. <4> The total amount of the asphalt (c) and the straight asphalt (b) is 3 to 10 parts by mass per 100 parts by mass of the aggregate. <1> ~ <3> 13. A method for producing an asphalt mixture according to claim 12. <5> The asphalt mixture contains the silicon element contained in the modified hydrogenated petroleum resin (a) in an amount of 1.3 to 4.0 ppm by mass in terms of silicon atoms. <1> ~ <4> 13. A method for producing an asphalt mixture according to claim 12. <6> The above <1> ~ <5> An asphalt masterbatch for use in the method for producing an asphalt mixture according to any one of the preceding claims, An asphalt masterbatch comprising: 10 to 50 mass % of a modified hydrogenated petroleum resin (a) satisfying the following (1) to (3); and straight asphalt (b). (1) Contains 0.5 to 20.0 mass% silicon element calculated as silicon atom (2) Weight average molecular weight is 500 to 5,000 (3) Molecular weight distribution (Mw / Mn) is 1.1 to 3.5 Effect of the Invention

[0007] According to the present invention, it is possible to provide a method for producing an asphalt mixture that can efficiently bring out the water resistance improving effect of an additive and obtain an asphalt mixture having excellent water resistance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Asphalt mixture manufacturing method] The method for producing an asphalt mixture of the present invention includes a step of mixing 0.03 to 4 parts by mass of an asphalt master batch with 100 parts by mass of aggregate at 100 to 200°C, and a step of further adding and mixing asphalt (c), wherein the asphalt master batch contains 10 to 50% by mass of a modified hydrogenated petroleum resin (a) satisfying the following (1) to (3), and straight asphalt (b). (1) Contains 0.5 to 20.0 mass% silicon element calculated as silicon atom (2) Weight average molecular weight is 500 to 5,000 (3) Molecular weight distribution (Mw / Mn) is 1.1 to 3.5

[0009] The reason why the method for producing an asphalt mixture of the present invention can efficiently bring out the water resistance improving effect of the additive and produce an asphalt mixture with excellent water resistance is not clear, but it is thought to be as follows. According to conventional technology, the additive silane-containing compound is mixed with the entire asphalt, so in the production of asphalt mixtures, most of the additive is located away from the aggregate, other than around the aggregate, and does not contribute to the adhesion between the aggregate and asphalt, which is inefficient. On the other hand, by first mixing an asphalt master batch containing a relatively large amount of the modified hydrogenated petroleum resin with aggregate, the aggregate surface can be efficiently coated with the additive, and the affinity between the aggregate surface and asphalt is expressed, improving adhesion. Therefore, it is believed that the water resistance improving effect of the additive can be efficiently brought out, and an asphalt mixture with excellent water resistance can be obtained. The method for producing the asphalt mixture of the present invention will be described in detail below.

[0010] <Asphalt master batch mixing process> The method for producing an asphalt mixture of the present invention includes a step of mixing 0.03 to 4 parts by mass of an asphalt master batch with 100 parts by mass of aggregate at 100 to 200° C. The asphalt master batch contains 10 to 50% by mass of a modified hydrogenated petroleum resin (a) that satisfies the following (1) to (3), and straight asphalt (b). (1) Contains 0.5 to 20.0 mass% silicon element calculated as silicon atom (2) Weight average molecular weight is 500 to 5,000 (3) Molecular weight distribution (Mw / Mn) is 1.1 to 3.5

[0011] (aggregate) The aggregate used in this step may be crushed stone, gravel, recycled aggregate, sand, or the like.

[0012] (Asphalt Masterbatch) The asphalt masterbatch used in this step contains 10 to 50 mass % of a modified hydrogenated petroleum resin (a) that satisfies the following (1) to (3), and straight asphalt (b). (1) Contains 0.5 to 20.0 mass% silicon element calculated as silicon atom (2) Weight average molecular weight is 500 to 5,000 (3) Molecular weight distribution (Mw / Mn) is 1.1 to 3.5

[0013] [Modified hydrogenated petroleum resin (a)] The modified hydrogenated petroleum resin (a) satisfies the above (1) to (3).

[0014] In this specification, the term "petroleum resin" refers to a resin obtained by polymerizing or copolymerizing one or more unsaturated compounds selected from aliphatic olefins and aliphatic diolefins having 4 to 10 carbon atoms, which are obtained as by-products during the production of olefins such as ethylene by thermal decomposition of petroleum such as naphtha, or aromatic compounds having 8 or more carbon atoms and having an olefinically unsaturated bond. Petroleum resins can be roughly classified into, for example, "aliphatic petroleum resins" obtained by polymerizing aliphatic olefins or aliphatic diolefins, "aromatic petroleum resins" obtained by polymerizing aromatic compounds having olefinic unsaturated bonds, and "aliphatic-aromatic copolymer petroleum resins" obtained by copolymerizing aliphatic olefins or aliphatic diolefins with aromatic compounds having olefinic unsaturated bonds.

[0015] Examples of the aliphatic olefins having 4 to 10 carbon atoms include butene, pentene, hexene, and heptene. Examples of the aliphatic diolefins having 4 to 10 carbon atoms include butadiene, pentadiene, isoprene, piperylene, cyclopentadiene, dicyclopentadiene, and methylpentadiene. Examples of aromatic compounds having 8 or more carbon atoms and an olefinically unsaturated bond include styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, vinylxylene, indene, methylindene, and ethylindene. Furthermore, the raw material compounds for the petroleum resin do not all need to be by-products in the production of olefins by thermal decomposition of petroleum such as naphtha, and chemically synthesized unsaturated compounds may also be used.

[0016] Preferable examples of petroleum resins include dicyclopentadiene-based petroleum resins obtained by polymerization of cyclopentadiene or dicyclopentadiene, dicyclopentadiene-styrene-based petroleum resins obtained by copolymerizing these cyclopentadiene or dicyclopentadiene with styrene, C5-based petroleum resins obtained by polymerization of isoprene or piperylene, and C9-based petroleum resins obtained by polymerization of C9 monomers such as indene or vinyltoluene.

[0017] In this specification, the term "hydrogenated petroleum resin" refers to a petroleum resin obtained by adding hydrogen atoms to the above-mentioned petroleum resin. Hydrogenated petroleum resins include fully hydrogenated petroleum resins in which substantially no unsaturated bonds remain and partially hydrogenated petroleum resins in which unsaturated bonds remain, and fully hydrogenated petroleum resins are preferred. The hydrogenated petroleum resin is preferably a hydrogenated aliphatic-aromatic copolymer petroleum resin.

[0018] The modified hydrogenated petroleum resin (a) contains 0.5 to 20.0 mass % of silicon element calculated as silicon atom. The silicon element is preferably derived from an organosilane structure. The silicon element content can be measured by ICP emission spectrometry, specifically, by the method described in the examples. The modified hydrogenated petroleum resin (a) contains, in terms of silicon atoms, 0.5 to 20.0 mass%, preferably 0.5 to 10.0 mass%, more preferably 0.5 to 5.0 mass%, even more preferably 0.8 to 4.0 mass%, and even more preferably 0.8 to 1.8 mass% of silicon element. The modified hydrogenated petroleum resin (a) is preferably a silane-modified hydrogenated petroleum resin having an organosilane structure, and more preferably a modified hydrogenated petroleum resin in which an alkoxysilyl group is bonded to the main chain of the hydrogenated petroleum resin via a bond. Here, "the alkoxysilyl group is bonded to the main chain of the hydrogenated petroleum resin via a bonding portion" means that, for example, a bonding portion is bonded directly to a carbon atom contained in a hydrogenated polymer (hydrogenated petroleum resin) obtained by polymerizing aliphatic olefins, aliphatic diolefins, and an aromatic compound having an olefinically unsaturated bond as described above and adding hydrogen atoms, and further an alkoxysilyl group is bonded to the carbon atom. The alkoxysilyl group is preferably a trialkoxysilyl group having an alkoxy group having 1 to 20 carbon atoms, which may be linear or branched, and more preferably a trialkoxysilyl group having an alkoxy group having 1 to 10 carbon atoms, which may be linear or branched. Specific examples include a trimethoxysilyl group, a triethoxysilyl group, and a tripropoxysilyl group, and at least one selected from the group consisting of a trimethoxysilyl group and a triethoxysilyl group is preferred, and a trimethoxysilyl group is more preferred. The bonding portion may be any divalent or higher organic group that can bond to a carbon atom in the main chain of the hydrogenated petroleum resin and to which an alkoxysilyl group can be bonded, and is preferably an alkylene group, more preferably an alkylene group having 2 to 3 carbon atoms.

[0019] The weight average molecular weight (Mw) of the modified hydrogenated petroleum resin (a) is from 500 to 5,000, preferably from 600 to 3,000, more preferably from 700 to 2,000, and even more preferably from 800 to 1,500. The weight average molecular weight is an index of fluidity when melted. The smaller the weight average molecular weight, the greater the fluidity when melted, resulting in excellent spreading and adhesion to the aggregate surface while maintaining the water resistance, which is the effect of the present invention. The weight average molecular weight can be specifically measured by the method described in the Examples.

[0020] The molecular weight distribution (weight average molecular weight / number average molecular weight, Mw / Mn) of the modified hydrogenated petroleum resin (a) is from 1.1 to 3.5, preferably from 1.3 to 3.0, more preferably from 1.5 to 3.0, and even more preferably from 2.0 to 2.5. The molecular weight distribution indicates the degree of dispersion of molecular weights, and becomes broad when the amount of low molecular weight components or high molecular weight components is extremely large. The molecular weight distribution can be specifically measured by the method described in the Examples.

[0021] The number average molecular weight (Mn) of the modified hydrogenated petroleum resin (a) is preferably from 100 to 4,500, more preferably from 250 to 2,500, and even more preferably from 300 to 1,500.

[0022] The softening point of the modified hydrogenated petroleum resin (a) is preferably from 60 to 150°C, more preferably from 80 to 140°C, even more preferably from 90 to 130°C, and even more preferably from 98 to 120°C. The softening point can be measured by a ring and ball method, specifically, by the method described in the examples. When the softening point is within the above range, an excellent balance between water resistance and adhesion to the aggregate surface is achieved.

[0023] [Method for producing modified hydrogenated petroleum resin (a)] The method for producing the modified hydrogenated petroleum resin (a) is not particularly limited, but the following method is preferred from the viewpoint of efficiently introducing silane into the resin and improving water resistance. The method for producing the modified hydrogenated petroleum resin (a) is preferably a method in which a hydrogenated petroleum resin is reacted with a compound having a carbon-carbon double bond and an alkoxysilyl group in the presence of a compound that generates radicals.

[0024] The hydrogenated petroleum resin used in the above production method is synonymous with the "hydrogenated petroleum resin" described in the above section [Modified hydrogenated petroleum resin (a)], and specifically, is a petroleum resin obtained by adding hydrogen atoms to a petroleum resin. Hydrogenated petroleum resins include fully hydrogenated petroleum resins in which substantially no unsaturated bonds remain, and partially hydrogenated petroleum resins in which unsaturated bonds remain, and the hydrogenated petroleum resin used in the production method of the present invention is preferably a fully hydrogenated petroleum resin. The hydrogenated petroleum resin is preferably a hydrogenated aliphatic-aromatic copolymer petroleum resin.

[0025] The petroleum resin used as the raw material for the hydrogenated petroleum resin has the same meaning as the "petroleum resin" explained in the section [Modified hydrogenated petroleum resin (a)] above, and is specifically as follows. Petroleum resins are resins obtained by polymerizing or copolymerizing one or more unsaturated compounds selected from aliphatic olefins and aliphatic diolefins having 4 to 10 carbon atoms, which are obtained as by-products during the production of olefins such as ethylene by thermal decomposition of petroleum such as naphtha, or aromatic compounds having 8 or more carbon atoms and having an olefinically unsaturated bond. Petroleum resins can be roughly classified into, for example, "aliphatic petroleum resins" obtained by polymerizing aliphatic olefins or aliphatic diolefins, "aromatic petroleum resins" obtained by polymerizing aromatic compounds having olefinic unsaturated bonds, and "aliphatic-aromatic copolymer petroleum resins" obtained by copolymerizing aliphatic olefins or aliphatic diolefins with aromatic compounds having olefinic unsaturated bonds.

[0026] Examples of the aliphatic olefins having 4 to 10 carbon atoms include butene, pentene, hexene, and heptene. Examples of the aliphatic diolefins having 4 to 10 carbon atoms include butadiene, pentadiene, piperylene, isoprene, cyclopentadiene, dicyclopentadiene, and methylpentadiene. Examples of aromatic compounds having 8 or more carbon atoms and an olefinically unsaturated bond include styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, vinylxylene, indene, methylindene, and ethylindene. Furthermore, the raw material compounds for the petroleum resin do not all need to be by-products in the production of olefins by thermal decomposition of petroleum such as naphtha, and chemically synthesized unsaturated compounds may also be used.

[0027] Preferable examples of petroleum resins include dicyclopentadiene-based petroleum resins obtained by polymerization of cyclopentadiene or dicyclopentadiene, dicyclopentadiene-styrene-based petroleum resins obtained by copolymerizing these cyclopentadiene or dicyclopentadiene with styrene, C5-based petroleum resins obtained by polymerization of isoprene or piperylene, and C9-based petroleum resins obtained by polymerization of C9 monomers such as indene or vinyltoluene.

[0028] The compound having a carbon-carbon double bond and an alkoxysilyl group used in the above production method is a compound in which one or more organic groups having a carbon-carbon double bond and one or more alkoxy groups are bonded to a silicon atom. Examples of the organic group having a carbon-carbon double bond include vinyl, allyl, butenyl, cyclohexenyl, cyclopentadienyl, and (meth)acryloxypropyl, with vinyl, methacryloxy, and acryloxy groups being preferred. Examples of the alkoxy group include a methoxy group, an ethoxy group, an isopropoxy group, and a butoxy group. The number of alkoxy groups bonded to the silicon atom is preferably one or more, more preferably two or more, and even more preferably three. Specific examples of the compound having a carbon-carbon double bond and an alkoxysilyl group include vinyltriethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, and methacryloxypropyltriethoxysilane. Of these, at least one selected from the group consisting of vinyltriethoxysilane and vinyltrimethoxysilane is preferred, and vinyltrimethoxysilane is more preferred. The amount of the compound having a carbon-carbon double bond and an alkoxysilyl group used in the production method is, in terms of silicon atoms of the compound having a carbon-carbon double bond and an alkoxysilyl group, preferably 0.5 to 20.0 mass%, more preferably 0.5 to 10.0 mass%, even more preferably 0.5 to 5.0 mass%, still more preferably 0.8 to 4.0 mass%, and even more preferably 0.8 to 1.8 mass%, relative to the hydrogenated petroleum resin.

[0029] The radical-generating compound used in the above-mentioned production method can be a compound generally known as a radical polymerization initiator. The compound that generates radicals can be appropriately selected from, for example, various organic peroxides and azo compounds such as azobisisobutyronitrile and azobisisovaleronitrile, and among these, organic peroxides are preferred. Examples of organic peroxides include diacyl peroxides such as dibenzoyl peroxide, di-3,5,5-trimethylhexanoyl peroxide, dilauroyl peroxide, didecanoyl peroxide, and di(2,4-dichlorobenzoyl)peroxide; hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, and 2,5-dimethylhexane-2,5-dihydroperoxide; di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 1,1-di(t-butylperoxy)cyclohexane, 1,1-di(t-hexylperoxy)cyclohexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, α,α'-bis(t-butylperoxide), and α,α'-bis(t-butylperoxide). Examples of the peroxycarbonates include dialkyl peroxides such as diisopropyl peroxybenzene; peroxyketals such as 1,1-bis-t-butylperoxy-3,3,5-trimethylcyclohexane and 2,2-bis(t-butylperoxy)butane; alkyl peresters such as 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, n-butyl 4,4-di(t-butylperoxy)valerate, t-butyl peroxyoctoate, t-butyl peroxypivalate, t-butyl peroxyneodecanoate, and t-butyl peroxybenzoate; and peroxycarbonates such as di-2-ethylhexyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, and t-butyl peroxyisopropyl carbonate. Among these, dialkyl peroxides are preferred. These may be used alone or in combination of two or more. The amount of the radical-generating compound used is not particularly limited, but is preferably 0.01 to 10% by mass, and more preferably 0.01 to 5% by mass, based on the hydrogenated petroleum resin.

[0030] As described above, a suitable method for producing the modified hydrogenated petroleum resin (a) is a method of reacting a hydrogenated petroleum resin with a compound having a carbon-carbon double bond and an alkoxysilyl group in the presence of a compound that generates radicals. As long as the reaction proceeds sufficiently, there are no limitations on the reaction method. However, (1) a method of mixing a molten hydrogenated petroleum resin, a compound having a carbon-carbon double bond and an alkoxysilyl group, and a compound that generates radicals, and reacting the resulting mixture by generating radicals by heating or the like, is preferred, and (2) a method of dissolving a hydrogenated petroleum resin, a compound having a carbon-carbon double bond and an alkoxysilyl group, and a compound that generates radicals in an organic solvent, and reacting the resulting mixture by generating radicals by heating or the like is more preferred. (1) A method of mixing a molten hydrogenated petroleum resin, a compound having a carbon-carbon double bond and an alkoxysilyl group, and a compound that generates radicals, and reacting the resulting mixture by heating or the like is more preferred.

[0031] In the case of the above-mentioned method (1), it is preferable to melt the hydrogenated petroleum resin, mix it with a compound having a carbon-carbon double bond and an alkoxysilyl group, add a compound that generates radicals, and heat the mixture to react the hydrogenated petroleum resin with the carbon-carbon double bond portion of the compound having a carbon-carbon double bond and an alkoxysilyl group, thereby obtaining a modified hydrogenated petroleum resin. In the present method, when the hydrogenated petroleum resin has a low melt viscosity, it is preferable to carry out the reaction while stirring in a normal reaction apparatus, whereas when the hydrogenated petroleum resin has a high melt viscosity, it is preferable to carry out the reaction while melt-kneading using a roll mill, a Banbury mixer, an extruder, or the like. The reaction temperature is preferably from 100 to 300°C, more preferably from 100 to 200°C.

[0032] In the case of the above method (2), it is preferable to dissolve the hydrogenated petroleum resin in an organic solvent, mix it with a compound having a carbon-carbon double bond and an alkoxysilyl group, add a compound that generates radicals, and heat the mixture to react the hydrogenated petroleum resin with the carbon-carbon double bond portion of the compound having a carbon-carbon double bond and an alkoxysilyl group, thereby obtaining a modified hydrogenated petroleum resin. In the present method, examples of organic solvents that can be used include hydrocarbon solvents such as pentane, hexane, heptane, cyclohexane, toluene, xylene, and decahydronaphthalene; halogenated hydrocarbon solvents such as chlorobenzene, dichlorobenzene, and trichlorobenzene; and liquefied α-olefins. The reaction temperature is preferably from -50 to 300°C, more preferably from 0 to 300°C, further preferably from 100 to 300°C, and even further preferably from 100 to 200°C.

[0033] [Straight asphalt (b)] The straight asphalt (b) may be asphalt or a mixture thereof as specified in JIS K 2207. It is preferable to use the straight asphalt having a penetration grade of 40-60 or 200-300.

[0034] [Asphalt masterbatch composition and manufacturing method] The asphalt master batch contains 10 to 50 mass % of a modified hydrogenated petroleum resin (a) and straight asphalt (b). The content of the modified hydrogenated petroleum resin (a) in the asphalt master batch is 10 to 50 mass%, preferably 15 to 50 mass%, more preferably 15 to 45 mass%, even more preferably 20 to 45 mass%, still more preferably 20 to 40 mass%, even more preferably 25 to 40 mass%, and even more preferably 25 to 35 mass%.

[0035] The mass ratio [(a) / (b)] of the modified hydrogenated petroleum resin (a) to the straight asphalt (b) in the asphalt masterbatch is preferably 10 / 90 to 50 / 50, more preferably 15 / 85 to 50 / 50, even more preferably 15 / 85 to 45 / 55, still more preferably 20 / 80 to 45 / 55, still more preferably 20 / 80 to 40 / 60, still more preferably 25 / 75 to 40 / 60, and still more preferably 25 / 75 to 35 / 65.

[0036] The content of the straight asphalt (b) in the asphalt masterbatch is preferably 50 to 90 mass%, more preferably 50 to 85 mass%, even more preferably 55 to 85 mass%, still more preferably 55 to 80 mass%, even more preferably 60 to 80 mass%, even more preferably 60 to 75 mass%, and even more preferably 65 to 75 mass%.

[0037] By setting the content and mass ratio of the modified hydrogenated petroleum resin (a) and the straight asphalt (b) within the above ranges, the water resistance improving effect of the modified hydrogenated petroleum resin can be efficiently brought out, and an asphalt mixture with excellent water resistance can be obtained.

[0038] In addition to the modified hydrogenated petroleum resin (a) and the straight asphalt (b), the asphalt masterbatch may contain any additives within the scope of the present invention, as long as the additives do not impair the effects of the present invention. In addition, the asphalt masterbatch may contain asphalt base oil and reinforcing materials that are ultimately contained in the asphalt mixture, as long as the additives do not impair the effects of the present invention. Optional additives include antioxidants and the like.

[0039] An antioxidant may be added to enhance thermal stability. As the antioxidant, known antioxidants can be used. As the antioxidant, it is preferable to use a phenol-based antioxidant. Examples of the phenol-based antioxidant include triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,5-di-tert- Examples of such compounds include butyl-4-hydroxybenzylphosphonate-diethyl ester, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. Commercially available antioxidants that can be used include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (IRGANOX1010, manufactured by BASF Ltd.) and 1,3,5-tris-(3',5'-di-tert-butyl-4'-hydroxybenzyl)isocyanuric acid (ADEKA STAB AO-20, manufactured by ADEKA Corporation).

[0040] The asphalt masterbatch contains, in terms of silicon atoms, preferably 0.10 to 0.60 mass%, more preferably 0.13 to 0.50 mass%, even more preferably 0.13 to 0.45 mass%, still more preferably 0.13 to 0.40 mass%, even more preferably 0.15 to 0.40 mass%, even more preferably 0.20 to 0.40 mass%, even more preferably 0.20 to 0.30 mass%, and even more preferably 0.20 to 0.27 mass% of silicon element. From the viewpoint of achieving a more efficient water resistance improving effect in terms of the amount of the masterbatch used, the asphalt masterbatch contains silicon element in an amount calculated as silicon atoms, more preferably 0.15 to 0.50 mass%, even more preferably 0.20 to 0.50 mass%, even more preferably 0.20 to 0.50 mass%, and even more preferably 0.30 to 0.50 mass%. In the manufacturing method of the present invention, since an asphalt master batch containing the above-mentioned amount of silicon element can be used, the water resistance improving effect of the modified hydrogenated petroleum resin can be efficiently brought out, and an asphalt mixture having excellent water resistance can be obtained.

[0041] The method for producing the asphalt masterbatch is not limited, but it can be obtained as follows.

[0042] Specifically, the modified hydrogenated petroleum resin (a) and the straight asphalt (b) are heated and mixed to obtain a mixture. The additives described above, as well as the asphalt base oil and reinforcing material contained in the asphalt mixture described below, may also be mixed. The heated mixing is preferably carried out by stirring at 100° C. or higher using a stirring device. The heating temperature is preferably 100° C. or higher, and although there is no upper limit, it is preferably 200° C. or lower. The heating temperature is preferably 100 to 200° C., more preferably 100 to 180° C., even more preferably 100 to 170° C., still more preferably 100 to 160° C., and even more preferably 140 to 160° C. The resulting mixture can be pulverized, pelletized, or the like to obtain an asphalt master batch in the form of chunks, pellets, or the like.

[0043] (Asphalt masterbatch mixing conditions) This step is a step in which 0.03 to 4 parts by mass of asphalt master batch is mixed with 100 parts by mass of aggregate at 100 to 200°C. The amount of asphalt master batch used for mixing is 0.03 to 4 parts by mass, preferably 0.03 to 3 parts by mass, more preferably 0.03 to 2 parts by mass, even more preferably 0.04 to 2 parts by mass, still more preferably 0.04 to 1.0 part by mass, still more preferably 0.04 to 0.5 parts by mass, still more preferably 0.05 to 0.10 parts by mass, and still more preferably 0.05 to 0.08 parts by mass, relative to 100 parts by mass of aggregate. The temperature at which the asphalt master batch is mixed with the aggregate is 100 to 200° C., and from the viewpoint of suppressing the progression of crosslinking of the modified hydrogenated petroleum resin at high temperatures, it is preferably 100 to 180° C., more preferably 100 to 170° C., even more preferably 100 to 160° C., and even more preferably 140 to 160° C. Mixing at 160° C. or less is particularly preferred because it makes it possible to suppress crosslinking even when a high-concentration modified hydrogenated petroleum resin is used. Therefore, by mixing within the above temperature range, an asphalt mixture having excellent water resistance can be obtained.

[0044] The amount of the asphalt master batch and the amount of the modified hydrogenated petroleum resin (a) contained in the asphalt master batch are preferably adjusted in consideration of the silicon element content of the asphalt mixture. Preferably, the amount of the asphalt (c) in the next step is also adjusted in consideration of the silicon element content in the entire asphalt mixture. The silicon element content referred to here refers to the silicon element contained only in the modified hydrogenated petroleum resin (a), and does not include the silicon element contained in the aggregate, etc. The asphalt mixture contains, in terms of silicon atoms, preferably 1.0 to 6.0 ppm by mass, more preferably 1.3 to 5.0 ppm by mass, even more preferably 1.3 to 4.5 ppm by mass, still more preferably 1.3 to 4.0 ppm by mass, still more preferably 1.5 to 4.0 ppm by mass, still more preferably 2.0 to 4.0 ppm by mass, still more preferably 2.0 to 3.0 ppm by mass, and still more preferably 2.0 to 2.7 ppm by mass of silicon element contained in the modified hydrogenated petroleum resin (a). By including the silicon element contained in the modified hydrogenated petroleum resin (a) in the asphalt mixture in the above-mentioned amount, the water resistance improving effect of the modified hydrogenated petroleum resin can be efficiently brought out, and an asphalt mixture with excellent water resistance can be obtained.

[0045] In this process, the asphalt master batch is added to aggregate having a predetermined particle size and mixed at a predetermined rotation speed to obtain a mixture of the asphalt master batch and aggregate. The above-mentioned optional additives that may be contained in the asphalt master batch may be added when mixing the asphalt master batch and aggregate. By carrying out this process under the above conditions, the aggregate surface can be coated with the modified hydrogenated petroleum resin and straight asphalt, thereby efficiently bringing out the water resistance improving effect of the modified hydrogenated petroleum resin and producing an asphalt mixture with excellent water resistance.

[0046] <Asphalt addition mixing process> The method for producing an asphalt mixture of the present invention further comprises a step of adding and mixing asphalt (c) after the asphalt master batch mixing step. By this process, an asphalt mixture can be obtained, and the obtained asphalt mixture has excellent water resistance.

[0047] (Asphalt (c)) Examples of the asphalt (c) used in this step include straight asphalt, solvent deasphalt such as propane deasphalt, blown asphalt, semi-blown asphalt, and the like, and these may be used in combination.

[0048] The straight asphalt can be asphalt or a mixture thereof as specified in JIS K 2207. It is preferable to use the straight asphalt having a penetration grade of 40-60 or 200-300. Solvent deasphalted asphalt is the residue obtained by extracting solvent deasphalted oil (high viscosity lubricating oil fraction) from vacuum distillation residual oil (see "New Petroleum Dictionary," edited by the Japan Petroleum Institute, 1982, p. 308). It is called propane deasphalted asphalt when propane or propane and butane are used as the solvent. Blown asphalt is, for example, asphalt defined in JIS K 2207. Semi-blown asphalt is, for example, the semi-blown asphalt defined in "Asphalt Pavement Guidelines," published by the Japan Road Association, January 13, 1997, p. 51, Table 3.3.4. In this step, aromatic heavy mineral oil and reinforcing material may be used in addition to asphalt (c). Aromatic heavy mineral oil and reinforcing material may be used appropriately depending on the environment in which the asphalt mixture of the present invention is used. The aromatic heavy mineral oil and reinforcing material used in this step are contained in the resulting asphalt mixture. In addition to asphalt (c), aromatic heavy mineral oil and reinforcing material, any additive may be used within a range that does not impair the effects of the present invention. Any additive used in this step is contained in the resulting asphalt mixture.

[0049] (Aromatic heavy mineral oil) The aromatic heavy mineral oil can be a solvent-extracted oil obtained by deasphalting the residual oil of vacuum distillation of crude oil with propane or the like, and then subjecting the solvent-extracted oil to solvent extraction with a polar solvent such as furfural to obtain bright stock (heavy lubricating oil). It is preferable to add an extract as the aromatic heavy mineral oil.

[0050] The role of the extract is to increase the solubility of the thermoplastic elastomer in asphalt and prevent separation during storage stability, and the amount of extract required increases as the amount of thermoplastic elastomer added increases. Also, adding more extract than necessary for the amount of thermoplastic elastomer added reduces the elastic modulus of the asphalt (composition).

[0051] The content of the extract is determined taking into consideration the penetration, softening point, storage stability, complex modulus indicating strength, dynamic stability (DS) in a wheel tracking test, and bending work and bending stiffness indicating low-temperature properties. The amount of extract relative to the total of straight asphalt (b), asphalt (c), aromatic heavy mineral oil, and reinforcing material is preferably 2.0% by mass or more and 8.0% by mass or less, but the extract does not necessarily have to be used.

[0052] (Reinforcement) A thermoplastic elastomer may be used as the reinforcing material, and among the thermoplastic elastomers, SBS (styrene-butadiene-styrene copolymer) is preferred. The performance of SBS can be estimated mainly from its molecular weight and styrene content, which is the mass % of styrene contained in the SBS.

[0053] At present, the weight average molecular weight of SBS that is easily available industrially is from 120,000 to 250,000. The styrene content of SBS is from 25.0% by mass to 35.0% by mass, preferably from 27.0% by mass to 33.0% by mass.

[0054] In addition to the above, SBS with different molecular weights and styrene contents are available, and the molecular weight of these SBS is between 80,000 and 90,000. Furthermore, the styrene content is between 25.0% and 50.0% by mass of the total SBS.

[0055] Although SBS is not required, when SBS is used, the amount of SBS relative to the total of straight asphalt (b), asphalt (c), aromatic heavy mineral oil, and reinforcing material is preferably 7.0% by mass or less. By making the SBS content 7.0% by mass or less, it is possible to maintain the asphalt continuous phase, and it is possible to improve the water resistance of the dense-graded mixture with excellent water impermeability. On the other hand, when it is desired to produce an asphalt mixture with high drainage or water permeability by intentionally providing voids inside the pavement, it is possible to produce an asphalt mixture with high drainage or water permeability by causing a phase transition of SBS by making the SBS content more than 7.0% by mass.

[0056] The SBS may be a mixture of only one type of SBS, or may be a mixture of two or more types of SBS having specific molecular structures. Mixing only one type of SBS is preferable because it eliminates the complication of selecting and mixing two or more types of SBS and reduces the manufacturing labor.

[0057] (Optional Additives) In this step, in addition to the asphalt (c), the aromatic heavy mineral oil, and the reinforcing material, any additive may be used as long as it does not impair the effects of the present invention.

[0058] Optional additives include petroleum resins and hydrogenated petroleum resins obtained by adding hydrogen atoms to petroleum resins. Petroleum resins are resins obtained by polymerizing or copolymerizing one or more unsaturated compounds selected from aliphatic olefins and aliphatic diolefins having 4 to 10 carbon atoms, which are obtained as by-products during the production of olefins such as ethylene by thermal decomposition of petroleum such as naphtha, or aromatic compounds having 8 or more carbon atoms and having an olefinically unsaturated bond. Petroleum resins can be roughly classified into, for example, "aliphatic petroleum resins" obtained by polymerizing aliphatic olefins or aliphatic diolefins, "aromatic petroleum resins" obtained by polymerizing aromatic compounds having olefinic unsaturated bonds, and "aliphatic-aromatic copolymer petroleum resins" obtained by copolymerizing aliphatic olefins or aliphatic diolefins with aromatic compounds having olefinic unsaturated bonds. Examples of the aliphatic olefins having 4 to 10 carbon atoms include butene, pentene, hexene, and heptene. Examples of the aliphatic diolefins having 4 to 10 carbon atoms include butadiene, pentadiene, isoprene, piperylene, cyclopentadiene, dicyclopentadiene, and methylpentadiene. Examples of aromatic compounds having 8 or more carbon atoms and an olefinically unsaturated bond include styrene, α-methylstyrene, β-methylstyrene, vinyltoluene, vinylxylene, indene, methylindene, and ethylindene. Furthermore, the raw material compounds for the petroleum resin do not all need to be by-products in the production of olefins by thermal decomposition of petroleum such as naphtha, and chemically synthesized unsaturated compounds may also be used. Suitable examples of petroleum resins include dicyclopentadiene-based petroleum resins obtained by polymerization of cyclopentadiene or dicyclopentadiene, dicyclopentadiene-styrene-based petroleum resins obtained by copolymerizing these cyclopentadiene or dicyclopentadiene with styrene, C5-based petroleum resins obtained by polymerization of isoprene or piperylene, and C9-based petroleum resins obtained by polymerization of C9 monomers such as indene or vinyltoluene. Hydrogenated petroleum resins are petroleum resins obtained by adding hydrogen atoms to the above-mentioned petroleum resins, and include fully hydrogenated petroleum resins in which substantially no unsaturated bonds remain and partially hydrogenated petroleum resins in which unsaturated bonds remain, with partially hydrogenated petroleum resins being preferred.

[0059] In addition, as an optional additive, a polyethylene-based polyolefin can be used, specifically, Hi-Zex 1300J, Neo-Zex 20201J, Ult-Zex 15150J (manufactured by Prime Polymer Co., Ltd.), Affinity GA1950, Affinity GA1900H (manufactured by DOW), etc.

[0060] Other optional additives include antioxidants. An antioxidant may be added to enhance thermal stability. As the antioxidant, known antioxidants can be used. As the antioxidant, it is preferable to use a phenol-based antioxidant. Examples of the phenol-based antioxidant include triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,5-di-tert- Examples of such compounds include butyl-4-hydroxybenzylphosphonate-diethyl ester, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and 3,9-bis[2-{3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane. Commercially available antioxidants that can be used include pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] (IRGANOX1010, manufactured by BASF Ltd.) and 1,3,5-tris-(3',5'-di-tert-butyl-4'-hydroxybenzyl)isocyanuric acid (ADEKA STAB AO-20, manufactured by ADEKA Corporation).

[0061] (Asphalt addition mixing conditions) This step is a step of further adding and mixing asphalt (c) after the asphalt master batch mixing step. The amount of asphalt (c) added is preferably adjusted taking into consideration the amount of straight asphalt (b) contained in the asphalt masterbatch. In other words, when a large amount of straight asphalt (b) is used in the previous step, it is preferable to reduce the amount of asphalt (c) added in this step to adjust the amount of asphalt in the entire asphalt mixture.

[0062] The total amount of asphalt (c) and straight asphalt (b) is preferably 3 to 10 parts by mass, more preferably 3 to 9 parts by mass, even more preferably 3 to 8 parts by mass, still more preferably 3 to 7 parts by mass, still more preferably 3 to 6 parts by mass, and even more preferably 4 to 6 parts by mass, relative to 100 parts by mass of aggregate.

[0063] In this process, asphalt (c) is added to the mixture of aggregate and asphalt master batch, and mixed at a predetermined rotation speed to obtain an asphalt mixture. The aromatic heavy mineral oil, reinforcing material, and optional additives may be mixed simultaneously with asphalt (c), or may be mixed with asphalt (c) in advance and mixed with the mixture as an asphalt composition. The temperature when mixing the asphalt (c) with the mixture is preferably 100 to 200°C, more preferably 100 to 180°C, more preferably 100 to 170°C, even more preferably 100 to 160°C, and still more preferably 140 to 160°C. By carrying out this step under the above conditions, the aggregate surface can be coated with the modified hydrogenated petroleum resin and straight asphalt, and the water resistance improving effect of the modified hydrogenated petroleum resin can be efficiently brought out, so that an asphalt mixture with excellent water resistance can be obtained.

[0064] The asphalt mixture obtained as described above may be temporarily stored or preserved in a container in which the temperature is controlled so as to maintain a predetermined temperature.

[0065] <Asphalt mixture> The asphalt mixture obtained by the method for producing an asphalt mixture of the present invention preferably has the following composition. The asphalt mixture contains modified hydrogenated petroleum resin (a), straight asphalt (b) and asphalt (c), and may further contain any additives, aromatic heavy mineral oil, reinforcing materials, and the like.

[0066] The asphalt mixture contains, in terms of silicon atoms, preferably 1.0 to 6.0 ppm by mass, more preferably 1.3 to 5.0 ppm by mass, even more preferably 1.3 to 4.5 ppm by mass, still more preferably 1.3 to 4.0 ppm by mass, still more preferably 1.5 to 4.0 ppm by mass, still more preferably 2.0 to 4.0 ppm by mass, still more preferably 2.0 to 3.0 ppm by mass, and still more preferably 2.0 to 2.7 ppm by mass of silicon element contained in the modified hydrogenated petroleum resin (a). By including the silicon element contained in the modified hydrogenated petroleum resin (a) in the asphalt mixture in the above-mentioned amount, the water resistance improving effect of the modified hydrogenated petroleum resin can be efficiently brought out, and an asphalt mixture with excellent water resistance can be obtained.

[0067] The total amount of asphalt (c) and straight asphalt (b) contained in the asphalt mixture is preferably 3 to 10 parts by mass, more preferably 3 to 9 parts by mass, even more preferably 3 to 8 parts by mass, still more preferably 3 to 7 parts by mass, still more preferably 3 to 6 parts by mass, and even more preferably 4 to 6 parts by mass, relative to 100 parts by mass of aggregate.

[0068] The total amount of the modified hydrogenated petroleum resin (a) and straight asphalt (b) contained in the asphalt mixture is 0.03 to 4 parts by mass, preferably 0.03 to 3 parts by mass, more preferably 0.03 to 2 parts by mass, even more preferably 0.04 to 2 parts by mass, still more preferably 0.04 to 1.0 part by mass, still more preferably 0.04 to 0.5 parts by mass, still more preferably 0.05 to 0.10 parts by mass, and still more preferably 0.05 to 0.08 parts by mass, relative to 100 parts by mass of aggregate.

[0069] The content of the modified hydrogenated petroleum resin (a) relative to the total content of the modified hydrogenated petroleum resin (a) and the straight asphalt (b) is 10 to 50 mass%, preferably 15 to 50 mass%, more preferably 15 to 45 mass%, even more preferably 20 to 45 mass%, still more preferably 20 to 40 mass%, still more preferably 25 to 40 mass%, and even more preferably 25 to 35 mass%.

[0070] The mass ratio of the modified hydrogenated petroleum resin (a) to the straight asphalt (b) [(a) / (b)] is preferably 10 / 90 to 50 / 50, more preferably 15 / 85 to 50 / 50, even more preferably 15 / 85 to 45 / 55, still more preferably 20 / 80 to 45 / 55, still more preferably 20 / 80 to 40 / 60, still more preferably 25 / 75 to 40 / 60, and still more preferably 25 / 75 to 35 / 65.

[0071] The content of straight asphalt (b) relative to the total content of modified hydrogenated petroleum resin (a) and straight asphalt (b) is preferably 50 to 90 mass%, more preferably 50 to 85 mass%, even more preferably 55 to 85 mass%, still more preferably 55 to 80 mass%, still more preferably 60 to 80 mass%, still more preferably 60 to 75 mass%, and still more preferably 65 to 75 mass%.

[0072] The asphalt mixture is obtained by the above-mentioned method for producing an asphalt mixture and has the above-mentioned composition, so that the water resistance improving effect of the modified hydrogenated petroleum resin can be efficiently brought out, and an asphalt mixture having excellent water resistance can be obtained. EXAMPLES

[0073] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0074] [Analysis of modified hydrogenated petroleum resin] [1. Silicon content] 0.1 g of the sample (resin) was heated in an electric furnace at 550°C for 12 hours, and the ash was dissolved in alkali to prepare a measurement solution. ICP emission spectrometry was then performed using an ICP emission spectrometry analyzer "720-ES" (manufactured by Agilent Technologies, Inc.) to determine the silicon content in terms of silicon atoms. The silicon element content derived from the modified hydrogenated petroleum resin in the asphalt master batch, the silicon element content derived from the modified hydrogenated petroleum resin in the asphalt composition, and the silicon element content derived from the modified hydrogenated petroleum resin in the asphalt mixture were calculated using the silicon element content, calculated in terms of silicon atoms, of the modified hydrogenated petroleum resin obtained above.

[0075] 2. Molecular weight and molecular weight distribution The average molecular weight of the resin was measured by gel permeation chromatography (GPC). For the measurement, a GPC measuring device "HLC-8321GPC / HT" (manufactured by Tosoh Technosystems Co., Ltd.) was used, as a detector, a liquid chromatogram RI detector "WATERS 150C" (manufactured by Waters Corporation) was used as a detector, two TOSOH GMHHR-H(S)HT columns were used as a detector, and 1,2,4-trichlorobenzene was used as an eluent. The number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were obtained, and the molecular weight distribution (Mw / Mn) of the resin was calculated.

[0076] [3. Softening point] Measurement was performed according to JIS K 6863.

[0077] [Analysis and evaluation of asphalt mixtures] [1. Evaluation of peel resistance (evaluation of water resistance)] This evaluation was carried out for each of the Examples and Comparative Examples. Ten pieces of asphalt mixture were selected and placed in 100 mL of 1.0 mol / L sodium carbonate aqueous solution. The aqueous solution was then heated on a hot plate, and heated for 1 minute after reaching 90°C. After cooling, the top surface of the asphalt mixture was visually observed, and the peeled area ratio of the asphalt covering the surface of the aggregate was calculated and expressed as a percentage (%). Evaluation was also performed according to the following criteria. The smaller the peeled area ratio of the top surface of the asphalt mixture, the more the peeling of the asphalt is suppressed and the better the water resistance of the asphalt mixture. A: Peeling area rate is 10% or less B: Peeling area rate is over 10% and 30% or less C: Peeling area rate is over 30%

[0078] [Production of modified hydrogenated petroleum resin] Manufacturing Example 1 100 g of hydrogenated petroleum resin (trade name "Imarv P-100" manufactured by Idemitsu Kosan Co., Ltd.) was placed in a 500 mL separable flask equipped with a nitrogen inlet tube and a stirring blade, and was heated and melted at 160° C. in an oil bath under a nitrogen stream. Once the hydrogenated petroleum resin was dissolved, 3.2 g of vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) was added with stirring, and the mixture was stirred until it became homogenous. Next, 0.69 g of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (manufactured by NOF Corporation, product name "Perhexa (registered trademark) 25B") was added dropwise as an organic peroxide. After the addition, the mixture was reacted for 1 hour at an internal temperature (reaction mixture temperature) of 160°C. After the reaction was completed, the mixture was dried for 1 hour at 150°C under reduced pressure and stirring to obtain modified hydrogenated petroleum resin a. The analysis and evaluation results of the obtained modified hydrogenated petroleum resin a are shown in Table 1.

[0079] Manufacturing Example 2 A modified hydrogenated petroleum resin b was obtained in the same manner as in Production Example 1, except that the amount of vinyltrimethoxysilane was changed to 4.7 g in Production Example 1. The analysis and evaluation results of the obtained modified hydrogenated petroleum resin b are shown in Table 1.

[0080] Production Example 3 A modified hydrogenated petroleum resin c was obtained in the same manner as in Production Example 1, except that the amount of vinyltrimethoxysilane was changed to 8.3 g in Production Example 1. The analysis and evaluation results of the obtained modified hydrogenated petroleum resin c are shown in Table 1.

[0081] Production Example 4 A modified hydrogenated petroleum resin d was obtained in the same manner as in Production Example 1, except that the amount of vinyltrimethoxysilane was changed to 10.0 g in Production Example 1. The analysis and evaluation results of the obtained modified hydrogenated petroleum resin d are shown in Table 1.

[0082] [Table 1]

[0083] [Asphalt masterbatch manufacturing] Manufacturing Examples 5-9 The modified hydrogenated petroleum resins obtained in Production Examples 1 to 4 and straight asphalt (Idemitsu Kosan Co., Ltd., penetration 72) were placed in a stainless steel 200 mL cylindrical container in the ratio shown in Table 2, and mixed by stirring for 15 minutes using a stirring device and a mantle heater at 160°C and a rotation speed of 2,000 rpm or more and 4,000 rpm or less to obtain the asphalt master batches shown in Table 2.

[0084] [Table 2]

[0085] [Manufacturing of asphalt mixture] Example 1 (Asphalt master batch mixing process) Hard sandstone aggregate of crushed stone No. 6 was washed with water and dried, and the asphalt master batch A obtained in Production Example 5 was heated at 160°C for 1 hour. 0.1 g of asphalt master batch A was then added to 95 g of hard sandstone aggregate, and the mixture was stirred for 3 minutes to obtain a mixture of asphalt master batch and aggregate. (Asphalt addition mixing process) Next, 4.9 g of straight asphalt was added to the total mixture of asphalt master batch and aggregate (95.1 g) and stirred for 3 minutes to obtain an asphalt mixture. The composition and evaluation results of the obtained asphalt mixture are shown in Table 3.

[0086] Examples 2 to 4 (Asphalt master batch mixing process) An asphalt mixture was obtained in the same manner as in Example 1, except that the asphalt masterbatch used in the asphalt masterbatch mixing step in Example 1 was changed to the type and amount of the masterbatch shown in Table 3. The composition and evaluation results of the obtained asphalt mixture are shown in Table 3.

[0087] Comparative Example 1 Hard sandstone aggregate of No. 6 crushed stone was washed with water and dried, and the asphalt composition obtained in Production Example 9 was heated at 180°C for 1 hour. 5.0 g of the asphalt composition was added to 95 g of hard sandstone aggregate and stirred for 3 minutes to obtain an asphalt mixture. The composition and evaluation results of the obtained asphalt mixture are shown in Table 3.

[0088] [Table 3]

[0089] From the results in Table 3, it can be seen that the asphalt mixture obtained by the manufacturing method of the asphalt mixture of the embodiment has excellent peeling resistance after hot water treatment. Therefore, the asphalt mixture obtained by the manufacturing method of the asphalt mixture of the present invention has a high peeling prevention effect because the water resistance improving effect of the modified hydrogenated petroleum resin can be efficiently brought out. In addition, since a higher concentration of modified hydrogenated petroleum resin than before can be used while suppressing unnecessary reactions such as crosslinking, it has a higher peeling prevention effect. As described above, the manufacturing method of the asphalt mixture of the present invention can efficiently bring out the water resistance improving effect of the additive, and can obtain an asphalt mixture with excellent water resistance.

Claims

1. The method includes a step of mixing 0.03 to 4 parts by mass of an asphalt master batch with respect to 100 parts by mass of aggregate at 100 to 200°C, and a step of further adding and mixing asphalt (c), The asphalt masterbatch comprises 10 to 50% by mass of a modified hydrogenated petroleum resin (a) that satisfies the following (1) to (3), and straight asphalt (b). (1) Contains 0.5 to 20.0 mass% silicon element calculated as silicon atom (2) Weight average molecular weight of 500 to 5,000 (3) Molecular weight distribution (Mw / Mn) is 1.1 to 3.5

2. The method for producing an asphalt mixture according to claim 1, wherein the softening point of the modified hydrogenated petroleum resin (a) is 60 to 150°C.

3. The mass ratio [(a) / (b)] of the modified hydrogenated petroleum resin (a) to the straight asphalt (b) in the asphalt masterbatch is 10 / 90 to 50 / 50. The method for producing an asphalt mixture according to claim 1 or 2.

4. The method for producing an asphalt mixture according to any one of claims 1 to 3, wherein the total amount of the asphalt (c) and the straight asphalt (b) is 3 to 10 parts by mass per 100 parts by mass of the aggregate.

5. The method for producing an asphalt mixture according to any one of claims 1 to 4, wherein the asphalt mixture contains 1.3 to 4.0 ppm by mass of silicon element contained in the modified hydrogenated petroleum resin (a) in terms of silicon atoms.

6. An asphalt masterbatch used in the method for producing an asphalt mixture according to any one of claims 1 to 5, An asphalt masterbatch comprising 10 to 50 mass% of a modified hydrogenated petroleum resin (a) satisfying the following (1) to (3) and straight asphalt (b). (1) Contains 0.5 to 20.0 mass% silicon element calculated as silicon atom (2) Weight average molecular weight of 500 to 5,000 (3) Molecular weight distribution (Mw / Mn) is 1.1 to 3.5

Images