Asphalt modifier

Abstract

To provide an asphalt modifier that enables obtaining an asphalt composition having excellent weather resistance, and an asphalt composition using the asphalt modifier.SOLUTION: An asphalt modifier contains a polyester resin, wherein the polyester resin is a composite resin including a polyester resin segment containing a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from polyethylene terephthalate, a vinyl resin segment containing a structural unit derived from a styrene-based compound, and a structural unit derived from a bifunctional reactive monomer, and a weight-average molecular weight of the polyester resin is 30,000 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an asphalt modifier and an asphalt composition. [Background technology]

[0002] Asphalt pavement, which uses an asphalt mixture obtained by adding aggregate to an asphalt composition (asphalt binder), 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, the paved road has good hardness and durability.

[0003] For example, Patent Document 1 discloses an asphalt emulsion containing composite particles for the purpose of improving the weather resistance of asphalt pavement, the composite particles containing asphalt and polyester and having a volume median particle size (D 50 ) is a composite particle of 1 μm or more and 40 μm or less is described. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-112510 Summary of the Invention [Problem to be solved by the invention]

[0005] Asphalt pavement has the problem that when exposed to sunlight for a long period of time, ultraviolet rays cause deterioration and cracks. This problem is particularly serious in areas with strong sunlight irradiation. When asphalt pavement deteriorates, repairs become necessary. Pavement repairs increase maintenance costs and have a significant impact on automobile traffic. Therefore, there is a demand for asphalt pavement that is less susceptible to deterioration by ultraviolet rays and has excellent weather resistance. Although the asphalt emulsion described in Patent Document 1 can improve the weather resistance of asphalt pavement to a certain extent, further improvement in weather resistance is desired. The present invention relates to an asphalt modifier that can produce an asphalt composition with excellent weather resistance, and an asphalt composition that uses the asphalt modifier. [Means for solving the problem]

[0006] The present inventors have discovered that the above problems can be solved by using an asphalt modifier containing a polyester resin having a specific structure including structural units derived from polyethylene terephthalate and a specific weight average molecular weight. That is, the present invention includes the following [1] and [2]. [1] An asphalt modifier containing a polyester resin, An asphalt modifier, wherein the polyester-based resin is a composite resin containing a polyester resin segment containing a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from polyethylene terephthalate, a vinyl-based resin segment containing a structural unit derived from a styrene-based compound, and a structural unit derived from a bireactive monomer, and the weight-average molecular weight of the polyester-based resin is 30,000 or less. [2] An asphalt composition containing asphalt and the asphalt modifier described in [1] above. [Effects of the Invention]

[0007] The present invention can provide an asphalt modifier that can produce an asphalt composition with excellent weather resistance, and an asphalt composition that uses the asphalt modifier. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Asphalt modifier] The asphalt modifier of the present invention comprises a polyester resin, which is a composite resin comprising a polyester resin segment containing structural units derived from an alcohol component, structural units derived from a carboxylic acid component, and structural units derived from polyethylene terephthalate, a vinyl resin segment containing structural units derived from a styrene compound, and structural units derived from a bireactive monomer, and the weight-average molecular weight of the polyester resin is 30,000 or less. The asphalt modifier of the present invention may comprise one type of polyester resin alone or a combination of two or more types. By mixing the asphalt modifier of the present invention with asphalt, an asphalt composition with excellent weather resistance can be obtained.

[0009] The reason why the present invention has an effect is not clear, but is thought to be as follows. The polyester resin contained in the asphalt modifier of the present invention is a composite resin containing polyester resin segments including structural units derived from alcohol components, structural units derived from carboxylic acid components, and structural units derived from polyethylene terephthalate (PET), vinyl resin segments including structural units derived from styrene compounds, and structural units derived from bireactive monomers. The polyester resin does not contain double bonds within its structure and acts as a UV absorber in asphalt, making it resistant to UV degradation. Furthermore, when the polyester resin contains vinyl resin segments and has a weight-average molecular weight of 30,000 or less, the vinyl resin segments act as compatible moieties with hydrophobic asphalt, allowing for uniform dispersion as fine particles in asphalt. Furthermore, during the production of polyester resins, during the polycondensation reaction of alcohol components, carboxylic acid components, bireactive monomers, and PET, the PET undergoes depolymerization and is incorporated into the polyester resin chain via a transesterification reaction. However, the PET is not incorporated in a completely randomized manner; rather, units that can be called PET segments are present in the resulting resin. These PET segments can act as polar group units in the molecule in the asphalt binder, and when they come into contact with highly polar materials such as glass, they adsorb to the surface of the material, forming a strong coating that is difficult to peel off, which is one of the reasons for improving the weather resistance of the asphalt composition. For this reason, it is believed that the asphalt modifier of the present invention has excellent weather resistance.

[0010] The definitions of various terms used in this specification are shown below. In the polyester-based resin, a "structural unit derived from an alcohol component" means a structure in which a hydrogen atom is removed from a hydroxy group of an alcohol component, and a "structural unit derived from a carboxylic acid component" means a structure in which a hydroxy group is removed from a carboxy group of a carboxylic acid component. The term "carboxylic acid component" encompasses not only the carboxylic acid itself, but also anhydrides that decompose to produce an acid during the reaction, and alkyl esters of carboxylic acids (for example, alkyl groups having 1 to 3 carbon atoms). When the carboxylic acid component is an alkyl ester of carboxylic acid, the number of carbon atoms in the alkyl group that is the alcohol residue of the ester is not included in the number of carbon atoms of the carboxylic acid.

[0011] <Polyester resin> The polyester-based resin is a composite resin containing a polyester resin segment containing a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from polyethylene terephthalate, a vinyl resin segment containing a structural unit derived from a styrene compound, and a structural unit derived from a bireactive monomer, and the weight-average molecular weight of the polyester-based resin is 30,000 or less. The polyester resin segment, the vinyl resin segment, and the physical properties of the polyester resin will be described below. The polyester resin may be either amorphous or crystalline, but is preferably amorphous.

[0012] (Polyester resin segment) The polyester resin segment contains a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from polyethylene terephthalate, i.e., is a polycondensate of an alcohol component, a carboxylic acid component, and polyethylene terephthalate (PET). Examples of the alcohol component include alkylene oxide adducts of aromatic diols, aliphatic diols, alicyclic diols, and trihydric or higher polyhydric alcohols. Among these, alkylene oxide adducts of aromatic diols and aliphatic diols are preferred.

[0013] The alkylene oxide adduct of an aromatic diol is preferably an alkylene oxide adduct of bisphenol A, more preferably an alkylene oxide adduct of formula (I):

[0014] [ka] (In the formula, OR 1 and R 2 O is an oxyalkylene group, and R 1 and R 2 are each independently an ethylene group or a propylene group, x and y are each a positive number that indicates the average number of moles of alkylene oxide added, and the sum of x and y is 1 or more, preferably 1.5 or more, and 16 or less, preferably 8 or less, and more preferably 4 or less.

[0015] Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A. The content of the alkylene oxide adduct of bisphenol A in the alcohol component is preferably 25 mol% or more, more preferably 30 mol% or more, even more preferably 35 mol% or more, and preferably 55 mol% or less, more preferably 50 mol% or less, even more preferably 45 mol% or less.

[0016] Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,2-propanediol, 3-methyl-1,5-pentanediol, and neopentyl glycol, with neopentyl glycol being preferred.

[0017] The amount of structural units derived from aliphatic diols in the structural units derived from the alcohol component is preferably 35 mol% or more, more preferably 45 mol% or more, even more preferably 55 mol% or more, and is preferably 75 mol% or less, more preferably 70 mol% or less, even more preferably 65 mol% or less.

[0018] The amount of PET-derived ethylene glycol structural units in the aliphatic diol-derived structural units is preferably 85 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and is 100 mol% or less, preferably 100 mol% or less. As will be described later, the constituent units derived from alcohol components include constituent units derived from ethylene glycol, which is derived from PET.

[0019] Examples of alicyclic diols include hydrogenated bisphenol A [2,2-bis(4-hydroxycyclohexyl)propane] and adducts of hydrogenated bisphenol A with alkylene oxides having 2 to 4 carbon atoms (average number of added moles: 2 to 12).

[0020] Examples of trihydric or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0021] Examples of the carboxylic acid component include dicarboxylic acids and trivalent or higher polycarboxylic acids.

[0022] Examples of dicarboxylic acids include aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and alicyclic dicarboxylic acids. Among these, at least one selected from aromatic dicarboxylic acids and aliphatic dicarboxylic acids is preferred.

[0023] Examples of aromatic dicarboxylic acids include phthalic acid, isophthalic acid, and terephthalic acid. Among these, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred. The amount of structural units derived from aromatic dicarboxylic acids in the structural units derived from the carboxylic acid component is preferably 75 mol% or more, more preferably 80 mol% or more, even more preferably 85 mol% or more, and is preferably 97 mol% or less, more preferably 95 mol% or less, even more preferably 93 mol% or less.

[0024] The amount of terephthalic acid constituent units derived from PET is preferably 55 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, and preferably 85 mol% or less, more preferably 80 mol% or less, even more preferably 75 mol% or less, of the constituent units derived from aromatic dicarboxylic acids.

[0025] The aliphatic dicarboxylic acid preferably has 2 or more carbon atoms, more preferably 3 or more carbon atoms, and preferably has 30 or less carbon atoms, more preferably 20 or less carbon atoms. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, maleic acid, fumaric acid, succinic acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, azelaic acid, and succinic acid substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms. Examples of succinic acid substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Among these, adipic acid and succinic acid substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms are preferred, and succinic acid substituted with an aliphatic hydrocarbon group having from 1 to 20 carbon atoms is more preferred. When the carboxylic acid component contains an aliphatic dicarboxylic acid, the amount of the aliphatic dicarboxylic acid in the carboxylic acid component is preferably 3 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, and preferably 25 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less.

[0026] An example of the alicyclic dicarboxylic acid is cyclohexanedicarboxylic acid.

[0027] The trivalent or higher polyvalent carboxylic acid is preferably a trivalent carboxylic acid, such as trimellitic acid. When the carboxylic acid component contains a trivalent or higher polycarboxylic acid, the amount of the trivalent or higher polycarboxylic acid in the carboxylic acid component is preferably 3 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, and is preferably 25 mol% or less, more preferably 20 mol% or less, even more preferably 15 mol% or less.

[0028] The structural units derived from the carboxylic acid component preferably include a structural unit derived from terephthalic acid and at least one selected from a structural unit derived from dodecenylsuccinic acid, a structural unit derived from trimellitic acid, and a structural unit derived from adipic acid, more preferably a structural unit derived from terephthalic acid and at least one selected from a structural unit derived from dodecenylsuccinic acid and a structural unit derived from adipic acid, and even more preferably a structural unit derived from terephthalic acid and a structural unit derived from dodecenylsuccinic acid.

[0029] PET is produced by the polycondensation reaction of an alcohol component with a carboxylic acid component, and / or by the depolymerization of a portion of PET. Ethylene glycol and terephthalic acid are produced as raw material monomers in the polycondensation reaction, and are then incorporated into polyester resins. PET is an equimolar polycondensation product of ethylene glycol and terephthalic acid, and the amounts of the constituent units derived from the alcohol component and the constituent units derived from the carboxylic acid component mentioned above include the constituent units derived from ethylene glycol and terephthalic acid, respectively, derived from PET. PET can be produced by conventional methods through the polycondensation of ethylene glycol with terephthalic acid, dimethyl terephthalate, or the like. The PET can be new virgin PET or recycled PET. Recycled PET is obtained by collecting used PET, washing it as needed, separating it from other materials, and then pulverizing it. The pulverized material is then depolymerized to break it down into monomer units, which are then used as raw materials for resynthesis.

[0030] From the viewpoint of weather resistance, the intrinsic viscosity (hereinafter also referred to as "IV value") of PET is preferably 0.40 or more, more preferably 0.50 or more, even more preferably 0.55 or more, and preferably 0.85 or less, more preferably 0.80 or less, even more preferably 0.75 or less, even more preferably 0.70 or less. The IV value is an index of molecular weight. The IV value of PET can be adjusted by the polycondensation time, etc. The IV value can be measured, for example, by dissolving a sample in a mixed solvent of phenol / tetrachloroethane = 60 / 40 (mass ratio) at a concentration of 0.4 g / dL, measuring with an Ubbelohde viscometer, and calculating according to the following formula.

[0031]

number

[0032] Commercially available PET products include, for example, "RAMAPET L1" (manufactured by Indorama Ventures, IV value: 0.60), "RAMAPET BF3067" (manufactured by Indorama Ventures, IV value: 0.65), "RAMAPET N2G" (manufactured by Indorama Ventures, IV value: 0.75), "TRN-NTJ" (manufactured by Teijin Limited, IV value: 0.53), "TRN-RTJC" (manufactured by Teijin Limited, IV value: 0.64), and "UK-31" (manufactured by Utsumi Recycle Systems Co., Ltd., IV value: 0.67).

[0033] In the polyester resin segment, the molar equivalent ratio of carboxy groups (COOH groups) of the carboxylic acid component to hydroxy groups (OH groups) of the alcohol component (COOH groups / OH groups) is preferably 0.7 or more, more preferably 0.8 or more, and preferably 1.3 or less, more preferably 1.2 or less. The hydroxy groups of the ambireactive monomer described below are not included in the hydroxy groups of the alcohol component, and the carboxy groups of the ambireactive monomer are not included in the carboxy groups of the carboxylic acid component. The "molar equivalent ratio (COOH groups / OH groups)" is calculated assuming that the alcohol component contains the same mole of ethylene glycol as the ethylene glycol-derived structural unit derived from PET, and that the carboxylic acid component contains the same mole of terephthalic acid as the terephthalic acid-derived structural unit derived from PET.

[0034] From the viewpoint of weather resistance, the PET content is preferably 30 mol% or more, more preferably 35 mol% or more, even more preferably 40 mol% or more, based on the total amount (100 mol%) of the alcohol component, carboxylic acid component, and PET, which are raw materials for the polyester resin segment, and is preferably 65 mol% or less, more preferably 60 mol% or less, even more preferably 55 mol% or less. Since PET is a polycondensation product of ethylene glycol with terephthalic acid, dimethyl terephthalate, etc., the terephthalic acid-ethylene glycol unit (Mw: 192) is counted as 1 mole. Therefore, moles of PET = moles of ethylene glycol = moles of terephthalic acid.

[0035] (Vinyl resin segment) The vinyl resin segment is an addition polymer of raw material monomers including a styrene compound. Examples of styrene compounds include unsubstituted or substituted styrene. Examples of the substituent substituted on styrene include an alkyl group having 1 to 5 carbon atoms, a halogen atom, an alkoxy group having 1 to 5 carbon atoms, a sulfonic acid group, or a salt thereof. Examples of styrene compounds include styrene, methylstyrene, α-methylstyrene, β-methylstyrene, tert-butylstyrene, chlorostyrene, chloromethylstyrene, methoxystyrene, styrenesulfonic acid, and salts thereof. Among these, styrene is preferred. The content of the styrene compound in the raw material monomers of the vinyl resin segment is preferably 85% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and is 100% by mass or less, preferably 100% by mass.

[0036] Examples of raw material monomers other than styrene-based compounds include (meth)acrylic acid esters such as benzyl (meth)acrylate and dimethylaminoethyl (meth)acrylate; olefins such as ethylene, propylene, and butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0037] (Structural units derived from bireactive monomers) The polyester resin has a structural unit derived from a bireactive monomer that is bonded to a polyester resin segment and a vinyl resin segment via a covalent bond. The term "structural unit derived from a bireactive monomer" refers to a unit formed by reaction of a functional group and an addition polymerizable group of a bireactive monomer. An example of the addition polymerizable group is a carbon-carbon unsaturated bond (ethylenically unsaturated bond). Examples of the bireactive monomer include addition polymerizable monomers having at least one functional group selected from a hydroxyl group, a carboxyl group, an epoxy group, a primary amino group, and a secondary amino group in the molecule. Among these, from the viewpoint of reactivity, addition polymerizable monomers having at least one functional group selected from a hydroxyl group and a carboxyl group are preferred, and addition polymerizable monomers having a carboxyl group are more preferred. Addition polymerizable monomers having a carboxyl group include addition polymerizable monomers having a substituent that generates a carboxyl group by transesterification. Examples of addition-polymerizable monomers having a carboxy group include acrylic acid, methacrylic acid, alkyl acrylate (the alkyl group has 1 to 18 carbon atoms), alkyl methacrylate (the alkyl group has 1 to 18 carbon atoms), fumaric acid, and maleic acid. Among these, from the viewpoint of reactivity in both polycondensation reactions and addition polymerization reactions, acrylic acid, methacrylic acid, and butyl acrylate are preferred, and butyl acrylate is more preferred. The amount of the structural units derived from the bireactive monomer is preferably 25% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, and is preferably 55% by mass or less, more preferably 50% by mass or less, even more preferably 45% by mass or less, based on 100% by mass of the total of the vinyl resin segment and the structural units derived from the bireactive monomer.

[0038] The content of the polyester resin segment in the polyester resin is preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and preferably 97% by mass or less, more preferably 95% by mass or less, even more preferably 93% by mass or less, based on 100% by mass of the total amount of the polyester resin segment and the vinyl resin segment. The structural unit derived from a bireactive monomer is referred to as a polyester resin segment.

[0039] The content of the vinyl resin segment in the polyester resin is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 7% by mass or more, and preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 20% by mass or less, based on 100% by mass of the total amount of the polyester resin segment and the vinyl resin segment.

[0040] The amount of structural units derived from bireactive monomers in the polyester resin is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, and is preferably 20% by mass or less, more preferably 15% by mass or less, even more preferably 10% by mass or less, based on 100% by mass of the total amount of the polyester resin segment and the vinyl resin segment.

[0041] The total amount of polyester resin segments and vinyl resin segments in the polyester resin is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and is 100% by mass or less, preferably 100% by mass.

[0042] The above amounts are calculated based on the ratio of the amounts of the polyester resin segment, raw material monomer for the vinyl resin segment, bireactive monomer, and radical polymerization initiator, and the mass of the polyester resin segment, etc. is based on the mass excluding the mass of water produced by polycondensation. When a radical polymerization initiator is used, the mass of the radical polymerization initiator is calculated by including it in the vinyl resin segment.

[0043] From the viewpoint of weather resistance, the weight average molecular weight of the polyester resin is 30,000 or less, preferably 25,000 or less, more preferably 20,000 or less, even more preferably 18,000 or less, and preferably 7,000 or more, more preferably 10,000 or more, even more preferably 13,000 or more.

[0044] (Physical properties of polyester resin) From the viewpoint of weather resistance, the softening point of the polyester resin is preferably 80°C or higher and 140°C or lower, more preferably 85°C or higher, even more preferably 90°C or higher, and more preferably 130°C or lower, even more preferably 120°C or lower, and even more preferably 115°C or lower. From the viewpoint of weather resistance, the glass transition point of the polyester resin is preferably 30°C or higher and 95°C or lower, more preferably 35°C or higher, even more preferably 40°C or higher, and more preferably 80°C or lower, even more preferably 70°C or lower, and even more preferably 60°C or lower. From the viewpoint of weather resistance, the acid value of the polyester resin is preferably 1 mgKOH / g or more and 50 mgKOH / g or less, more preferably 3 mgKOH / g or more, even more preferably 5 mgKOH / g or more, and more preferably 45 mgKOH / g or less, even more preferably 40 mgKOH / g or less. From the viewpoint of weather resistance, the hydroxyl value of the polyester resin is preferably 5 mgKOH / g or more and 50 gKOH / g or less, more preferably 10 mgKOH / g or more, even more preferably 15 mgKOH / g or more, and more preferably 45 mgKOH / g or less, even more preferably 40 mgKOH / g or less.

[0045] The softening point, glass transition temperature, acid value, and hydroxyl value of the polyester resin can be appropriately adjusted by the type and amount of raw material monomers used, as well as production conditions such as reaction temperature, reaction time, and cooling rate, and these values ​​can be determined by the methods described in the examples. When two or more polyester resins are used in combination, the softening point, glass transition temperature, acid value and hydroxyl value of the resulting mixture are preferably within the above ranges.

[0046] (Method of producing polyester resin) The polyester resin may be produced, for example, by a method including a step A of polycondensing an alcohol component and a carboxylic acid component, and a step B of addition-polymerizing a raw material monomer for a vinyl resin segment and a bireactive monomer. Step B may be carried out after step A, step B may be carried out after step A, or step A and step B may be carried out simultaneously. A preferred method is to subject a portion of the carboxylic acid component to a polycondensation reaction in step A, then carry out step B, and then add the remainder of the carboxylic acid component to the polymerization system to further promote the polycondensation reaction of step A and the polycondensation reaction with, for example, a carboxy group possessed by the bireactive monomer or the constituent unit derived from the bireactive monomer.

[0047] The polycondensation in step A can be carried out, for example, in an inert gas atmosphere, in the presence of an esterification catalyst, an esterification promoter, a polymerization inhibitor, etc., as necessary, at a temperature of about 120°C or higher and 250°C or lower. Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) di(2-ethylhexanoate), and titanium compounds such as titanium diisopropoxybis(triethanolaminate). Examples of the esterification co-catalyst that can be used together with the esterification catalyst include gallic acid (3,4,5-trihydroxybenzoic acid). The amount of the esterification catalyst used is preferably 0.01 to 10 parts by mass relative to 100 parts by mass of the total amount of the alcohol component, carboxylic acid component, and PET, which are raw materials for the polyester resin segment. The amount of the esterification promoter used is preferably 0.001 part by mass or more and 1 part by mass or less relative to 100 parts by mass of the total amount of the alcohol component, carboxylic acid component, and PET, which are raw materials for the polyester resin segment. Furthermore, examples of the polymerization inhibitor include radical polymerization inhibitors such as 4-tert-butylcatechol. When a polymerization inhibitor is used, the amount of the polymerization inhibitor used is preferably 0.001 part by mass or more and 1 part by mass or less per 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0048] Examples of the radical polymerization initiator for the addition polymerization in step B include peroxides such as dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile). The amount of the radical polymerization initiator used is preferably 1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the total amount of the raw material monomers of the vinyl resin segment and the bireactive monomer. The temperature of the addition polymerization is preferably 110°C or higher, more preferably 130°C or higher, and preferably 230°C or lower, more preferably 220°C or lower, and even more preferably 210°C or lower.

[0049] (Polyester resin content in asphalt modifier) The content of polyester resin in the asphalt modifier is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and is 100% by mass or less, preferably 100% by mass, of the total mass of the asphalt modifier.

[0050] The asphalt modifier of the present invention can be used, for example, by mixing it with asphalt to obtain an asphalt composition. For example, heated aggregate can be added to the obtained asphalt composition to form an asphalt mixture, which can then be used for paving. The asphalt modifier of the present invention can be suitably used as an asphalt modifier to be blended into asphalt mixtures containing aggregate.

[0051] [Asphalt composition] The asphalt composition of the present invention contains asphalt and the above-mentioned asphalt modifier. That is, the asphalt composition of the present invention contains asphalt and the polyester resin that constitutes the above-mentioned asphalt modifier.

[0052] <Asphalt> The asphalt composition of the present invention contains asphalt. As the asphalt, various types of asphalt can be used, including, for example, straight asphalt, which is petroleum asphalt for paving, and modified asphalt. Straight asphalt is the residual bitumen material obtained by subjecting crude oil to atmospheric distillation or vacuum distillation. Modified asphalts include blown asphalt, polymer-modified asphalt modified with polymeric materials such as thermoplastic elastomers and thermoplastic resins (hereinafter also referred to as "polymer-modified asphalt"). Blown asphalt refers to asphalt obtained by heating a mixture of straight asphalt and heavy oil and then blowing air into it to oxidize it. The asphalt is preferably selected from straight asphalt and polymer-modified asphalt, and from the viewpoint of the durability and weather resistance of the asphalt pavement, polymer-modified asphalt is more preferable, and polymer-modified asphalt type II, polymer-modified asphalt type III, and polymer-modified asphalt type H are more preferable, and polymer-modified asphalt type H is more preferable from the viewpoint of further increasing compatibility with thermoplastic elastomers.

[0053] (thermoplastic elastomer) Examples of thermoplastic elastomers in polymer-modified asphalt include styrene / butadiene block copolymers (hereinafter also referred to as "SB"), styrene / butadiene / styrene block copolymers (hereinafter also referred to as "SBS"), styrene / butadiene random copolymers (hereinafter also referred to as "SBR"), styrene / isoprene block copolymers (hereinafter also referred to as "SI"), styrene / isoprene / styrene block copolymers (hereinafter also referred to as "SIS"), styrene / isoprene random copolymers (hereinafter also referred to as "SIR"), ethylene / vinyl acetate copolymers, ethylene / acrylic acid ester copolymers, styrene / ethylene / butylene / styrene copolymers, styrene / ethylene / propylene / styrene copolymers, polyurethane-based thermoplastic elastomers, isobutylene / isoprene copolymers, polyisoprene, polychloroprene, synthetic rubbers other than those mentioned above, and at least one selected from natural rubber.

[0054] Among these, from the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the thermoplastic elastomer is preferably at least one selected from SB, SBS, SBR, SI, SIS, SIR, and ethylene / acrylic acid ester copolymers, more preferably at least one selected from SB, SBS, SBR, SI, SIS, and SIR, and even more preferably at least one selected from SBR and SBS. From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the content of thermoplastic elastomer in the polymer-modified asphalt is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and more preferably 15% by mass or less, even more preferably 5% by mass or less.

[0055] The content of polymer-modified asphalt in the asphalt composition is preferably 70% by mass or more and 99% by mass or less, more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and more preferably 98% by mass or less, even more preferably 97% by mass or less, even more preferably 96% by mass or less, from the viewpoint of exhibiting asphalt performance and obtaining an asphalt mixture that can maintain good adhesion between aggregates.

[0056] (Polyester Resin Content in Asphalt Composition) From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the content of polyester resin in the asphalt composition is preferably 0.5 parts by mass or more and 20 parts by mass or less, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and more preferably 13 parts by mass or less, even more preferably 10 parts by mass or less, and even more preferably 7 parts by mass or less, per 100 parts by mass of asphalt.

[0057] <Dispersant> The asphalt composition may further include a dispersant. Examples of dispersants include polymer dispersants such as polyamidoamines and their salts, polycarboxylic acids and their salts, high molecular weight unsaturated acid esters, modified polyurethanes, modified polyesters, modified poly(meth)acrylates, (meth)acrylic copolymers, and naphthalenesulfonic acid-formalin condensates. In the present invention, the term "polymer dispersant" refers to a dispersant having a weight-average molecular weight of 1,000 or more. However, from the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the content of dispersant is preferably less than 1 part by mass, more preferably less than 0.5 parts by mass, per 100 parts by mass of polyester resin, and even more preferably, it may be substantially free of dispersant.

[0058] <Water> The asphalt composition may contain water to the extent that the effects of the present invention are not impaired. The water content in the asphalt composition is preferably 0.5 mass% or less, more preferably 0.3 mass% or less, even more preferably 0.1 mass% or less, and even more preferably 0 mass%. The water content in the asphalt composition can be determined by the method described in the Examples.

[0059] [Method for producing asphalt composition] The asphalt composition of the present invention can be produced by mixing asphalt with the asphalt modifier. Specifically, the asphalt is heated and melted, the asphalt modifier is added, and the mixture is stirred and mixed in a commonly used mixer until the polyester resin is uniformly dispersed in the asphalt, thereby obtaining the asphalt composition. Commonly used mixers include a homomixer, a dissolver, a paddle mixer, a ribbon mixer, a screw mixer, a planetary mixer, a vacuum countercurrent mixer, a roll mill, and a twin-screw extruder.

[0060] The mixing temperature of the asphalt and the asphalt modifier is preferably 140°C or higher and 230°C or lower, more preferably 150°C or higher, even more preferably 160°C or higher, and more preferably 210°C or lower, even more preferably 200°C or lower, from the viewpoint of uniformly dispersing the polyester resin in the asphalt. Furthermore, the mixing time of the asphalt and the asphalt modifier is preferably 10 minutes or more, more preferably 20 minutes or more, from the viewpoint of uniformly dispersing the polyester resin in the asphalt, and is preferably 10 hours or less, more preferably 5 hours or less, even more preferably 3 hours or less, and even more preferably 1 hour or less.

[0061] The asphalt composition of the present invention is a binder composition, and can be used for paving, for example, by adding aggregate to the asphalt composition to form an asphalt mixture, or by mixing aggregate, the asphalt composition, and a polyester-based resin to form an asphalt mixture. In other words, the asphalt composition of the present invention is suitable for paving, and particularly suitable for road paving.

[0062] [Asphalt mixture] An asphalt mixture, which is a suitable example of the use of the asphalt composition, will now be described. The asphalt mixture contains aggregate and the asphalt composition. That is, the asphalt mixture contains at least aggregate, asphalt, and the polyester resin. The content of each component in the asphalt mixture of the present invention can be considered as the blending amount of each component in the asphalt mixture of the present invention.

[0063] <Aggregate> The aggregate can be selected from crushed stone, boulders, gravel, sand, recycled aggregate, ceramics, etc. In addition, the aggregate can be either coarse aggregate with a particle size of 2.36 mm or more or fine aggregate with a particle size of less than 2.36 mm, with a combination of coarse and fine aggregate being preferred. From the viewpoint of the durability of the asphalt pavement, the aggregate content in the asphalt mixture is preferably 85% by mass or more, more preferably 90% by mass or more, more preferably 92% by mass or more, and preferably 98% by mass or less, more preferably 97% by mass or less, and even more preferably 96% by mass or less.

[0064] <Additives> In addition to the aggregate, asphalt, and polyester resin described above, various additives conventionally used in asphalt mixtures, such as film-forming agents, thickening stabilizers, and emulsifiers, may also be added to the asphalt mixture as needed. The total content of these additives in the asphalt mixture is preferably 50% by mass or less, more preferably 25% by mass or less, and even more preferably 5% by mass or less.

[0065] [Asphalt mixture manufacturing method] There are no particular limitations on the method for producing the asphalt mixture, and any method may be used. Generally, the method can be carried out in accordance with the method for producing an asphalt mixture containing aggregate and asphalt. Specifically, the asphalt composition described above can be added to heated aggregate and mixed.

[0066] The temperature of the heated aggregate is preferably 130°C or higher and 230°C or lower, more preferably 150°C or higher, even more preferably 170°C or higher, and more preferably 210°C or lower, even more preferably 200°C or lower, from the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between the aggregates and from the viewpoint of preventing thermal degradation of the asphalt.

[0067] The mixing temperature of the aggregate and asphalt composition is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, from the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between the aggregates, and is preferably 230°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower, from the viewpoint of preventing thermal degradation of the asphalt. The mixing time of the aggregate and the asphalt composition is not particularly limited, but is preferably 30 seconds or more, more preferably 1 minute or more, and is preferably 2 hours or less, more preferably 1 hour or less, and even more preferably 30 minutes or less.

[0068] From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the method for producing an asphalt mixture may include a step of mixing aggregate and an asphalt composition and then holding the obtained asphalt mixture at the above-mentioned mixing temperature or a temperature equal to or higher than the mixing temperature. In the step of holding the asphalt mixture, the mixture may be further mixed. The retention time is preferably 0.5 hours or more, more preferably 1 hour or more, and even more preferably 1.5 hours or more. The upper limit of the time is not particularly limited, but is, for example, about 48 hours.

[0069] [Paving method] Asphalt mixtures are suitable for paving, and as described above, asphalt mixtures in which aggregate is added to an asphalt composition, or asphalt mixtures in which aggregate and an asphalt composition are mixed, are used for paving. The road paving method includes the steps of applying the asphalt mixture described above to a paving object such as a road or parking lot to form an asphalt pavement layer. Specifically, the paving method includes the steps of mixing the asphalt composition described above with heated aggregate to obtain an asphalt mixture (Step 1), and applying the asphalt mixture obtained in Step 1 to the paving object to form an asphalt pavement layer (Step 2). The asphalt pavement layer is preferably a base layer or a surface layer.

[0070] The asphalt mixture may be compacted and applied in the same manner using known construction machinery. From the viewpoint of the durability of the asphalt pavement, the compaction temperature when used as a heated asphalt mixture is preferably 100°C or higher, more preferably 120°C or higher, and even more preferably 130°C or higher, and is preferably 200°C or lower, more preferably 180°C or lower.

[0071] The present invention includes the following aspects. <1> An asphalt modifier containing a polyester resin, An asphalt modifier, wherein the polyester-based resin is a composite resin containing a polyester resin segment containing a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from polyethylene terephthalate, a vinyl-based resin segment containing a structural unit derived from a styrene-based compound, and a structural unit derived from a bireactive monomer, and the weight-average molecular weight of the polyester-based resin is 30,000 or less. <2> The structural units derived from the alcohol component include structural units derived from an alkylene oxide adduct of bisphenol A. <1> The asphalt modifier according to claim 1. <3> The structural unit derived from a carboxylic acid component includes a structural unit derived from terephthalic acid and at least one selected from a structural unit derived from dodecenylsuccinic acid, a structural unit derived from trimellitic acid, and a structural unit derived from adipic acid. <1> or <2> The asphalt modifier according to claim 1. <4> The weight average molecular weight of the polyester resin is 7,000 or more. <1> ~ <3> The asphalt modifier according to any one of the above. <5> Asphalt and <1> ~ <4> An asphalt composition comprising the asphalt modifier according to any one of the preceding claims. <6> The asphalt is polymer-modified asphalt H type; <5> The asphalt composition according to claim 1. <7> The water content in the asphalt composition is 0.5% by mass or less. <5> Or the asphalt composition according to <6>. <8> It is for paving, <5> ~ <7> The asphalt composition according to any one of the preceding claims. <9> Asphalt and <1> ~ <4> A method for improving the weather resistance of an asphalt composition, comprising a step of mixing the asphalt modifier according to any one of the above items. [Example]

[0072] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these examples in any way. In the notation "alkylene oxide (X)" and the like, the number X in parentheses means the average number of moles of alkylene oxide added.

[0073] The physical properties of the polyester resin were measured by the following methods. [Measurement method] [Softening point and glass transition point] (1) Softening point Using a flow tester "CFT-500D" (Shimadzu Corporation), 1 g of sample was heated at a temperature increase rate of 6°C / min, while applying a load of 1.96 MPa with the plunger, and extruded from a nozzle 1 mm in diameter and 1 mm in length. The plunger depression distance of the flow tester was plotted against the temperature, and the temperature at which half of the sample flowed out was taken as the softening point. (2) Glass transition temperature Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan Co., Ltd.), 0.01 to 0.02 g of sample was weighed into an aluminum pan, heated to 200°C, and cooled from 200°C to 0°C at a rate of 10°C / min. Measurements were then performed while the temperature was increased to 150°C at a rate of 10°C / min. The glass transition temperature was determined as the temperature at the intersection of an extension of the baseline below the maximum endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0074] [Acid value and hydroxyl value of polyester resin] The acid value and hydroxyl value of the polyester resin 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)).

[0075] [Weight average molecular weight of polyester resin] The weight average molecular weight was determined by gel permeation chromatography (GPC) according to the following method. (i) Preparation of sample solution The sample was dissolved in chloroform at 40° C. to a concentration of 0.5 g / 100 mL. Next, this solution was filtered using a polytetrafluoroethylene (PTFE) type membrane filter "DISMIC-25JP" (manufactured by Toyo Roshi Kaisha, Ltd.) with a pore size of 0.20 μm to remove insoluble components, and a sample solution was obtained. (ii) Molecular weight measurement The following measurement equipment and analytical column were used, and chloroform was used as the eluent at a flow rate of 1 mL per minute. The column was stabilized in a thermostatic bath at 40°C. 200 μL of sample solution was injected into the column and measurement was performed. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curve used here was prepared using several types of monodisperse polystyrene (A-500 (5.0 × 10) manufactured by Tosoh Corporation). 2 ), A-1000(1.01×10 3 ), A-2500(2.63×10 3 ), A-5000(5.97×10 3 ), F-1(1.02×10 4 ), F-2(1.81×10 4 ), F-4(3.97×10 4 ), F-10(9.64×10 4 ), F-20(1.90×10 5 ), F-40(4.27×10 5 ), F-80(7.06×10 5 ), F-128(1.09×10 6 )) was used as a standard sample. The molecular weight is shown in parentheses. Measuring device: "HLC-8320GPC" (Tosoh Corporation) Analytical column: "TSKgel Super HZM" + "TSKgel Super H-RC" x 2 (Tosoh Corporation)

[0076] [Water content in asphalt composition] Using an infrared moisture meter (Kett Electric Laboratory, "FD-230"), 5 g of the measurement sample was dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, fluctuation range 0.05%), and the moisture content (mass%) of the measurement sample was measured.

[0077] [Production of polyester resin] Resins A to D and e to h were produced as follows, and used as asphalt modifiers A to D and e to h, respectively, in the production of asphalt compositions described below.

[0078] Example 1 (Resin A) The BPA-PO listed in Table 1 was placed in a 5-liter four-neck flask equipped with a thermometer, stainless steel stirrer, downflow condenser, and nitrogen inlet tube and heated to 100°C. Terephthalic acid and PET (RAMAPET L1, manufactured by Indorama Ventures) were added at 100°C, and the temperature was increased to 165°C at 2°C / min. A mixture of styrene, n-butyl acrylate, and dibutyl peroxide was added dropwise over 1.5 hours at 165°C under a nitrogen atmosphere to conduct polymerization. After the dropwise addition, the temperature was maintained at 165°C for 30 minutes, and then the pressure was reduced to 8 kPa for 30 minutes. The pressure was returned to atmospheric pressure, and the temperature was increased to 200°C at 2°C / min. Tin(II) di(2-ethylhexanoate) and gallic acid (3,4,5-trihydroxybenzoic acid) were added, and the condensation polymerization reaction was carried out at 235°C for 6 hours. After cooling to 180°C, dodecenyl succinic anhydride was added, the temperature was raised from 180°C to 210°C, and the reaction was carried out at 210°C and 20 kPa until the softening point shown in Table 1 was reached, thereby obtaining Resin A.

[0079] Example 2 (Resin B) Resin B was obtained in the same manner as Resin A, except that the reaction was carried out until the softening point shown in Table 1 was reached.

[0080] Example 3 (Resin C) The BPA-PO listed in Table 1 was placed in a 5-liter four-neck flask equipped with a thermometer, stainless steel stirrer, downflow condenser, and nitrogen inlet tube and heated to 100°C. Terephthalic acid and PET (RAMAPET L1) were added at 100°C, and the temperature was increased to 165°C at 0.5°C / min. A mixture of styrene, n-butyl acrylate, and dibutyl peroxide was added dropwise over 1.5 hours at 165°C under a nitrogen atmosphere to conduct polymerization. After the dropwise addition, the temperature was maintained at 165°C for 30 minutes, and then the pressure was reduced to 8 kPa for 30 minutes. The pressure was returned to atmospheric pressure, and the temperature was increased to 200°C at 0.5°C / min. Tin(II) di(2-ethylhexanoate) and gallic acid (3,4,5-trihydroxybenzoic acid) were added, and the condensation polymerization reaction was carried out at 235°C for 6 hours. After cooling to 180°C, trimellitic anhydride was added, the temperature was raised from 180°C to 210°C, and the reaction was carried out at 210°C and 20 kPa until the softening point shown in Table 1 was reached, thereby obtaining Resin C.

[0081] Example 4 (Resin D) The BPA-PO listed in Table 1 was placed in a 5-liter four-neck flask equipped with a thermometer, stainless steel stirrer, downflow condenser, and nitrogen inlet tube and heated to 100°C. Terephthalic acid and PET (RAMAPET L1) were added at 100°C, and the temperature was increased to 165°C at 0.5°C / min. A mixture of styrene, n-butyl acrylate, and dibutyl peroxide was added dropwise over 1.5 hours at 165°C under a nitrogen atmosphere to conduct polymerization. After the dropwise addition, the temperature was maintained at 165°C for 30 minutes, and then the pressure was reduced to 8 kPa for 30 minutes. The pressure was returned to atmospheric pressure, and the temperature was increased to 200°C at 0.5°C / min. Tin(II) di(2-ethylhexanoate) and gallic acid (3,4,5-trihydroxybenzoic acid) were added, and the condensation polymerization reaction was carried out at 235°C for 6 hours. After cooling to 180°C, adipic acid was added, the temperature was raised from 180°C to 210°C, and the reaction was carried out at 210°C and 20 kPa until the softening point shown in Table 1 was reached, thereby obtaining Resin D.

[0082] Comparative Example 1 (Resin e) The BPA-PO listed in Table 1 was placed in a 5-liter four-neck flask equipped with a thermometer, a stainless steel stirrer, a downflow condenser, and a nitrogen inlet tube and heated to 100°C. After adding terephthalic acid and PET (RAMAPET L1) at 100°C, tin(II) di(2-ethylhexanoate) and gallic acid (3,4,5-trihydroxybenzoic acid) were added at 235°C under a nitrogen atmosphere. The temperature was increased to 235°C at a rate of 0.5°C / min. Polycondensation reaction was carried out at 235°C for 6 hours, followed by cooling to 180°C and the addition of adipic acid. The temperature was increased from 180°C to 220°C at a rate of 0.5°C / min, and the reaction was continued at 220°C and 20 kPa until the softening point listed in Table 1 was reached, yielding Resin e.

[0083] Comparative example 2 (resin f) The BPA-PO listed in Table 1 was placed in a 5-liter four-neck flask equipped with a thermometer, stainless steel stirrer, downflow condenser, and nitrogen inlet tube and heated to 100°C. Terephthalic acid and PET (RAMAPET L1) were added at 100°C, and the temperature was increased to 160°C at 2°C / min. A mixture of styrene, n-butyl acrylate, and dibutyl peroxide was added dropwise over 1.5 hours at 160°C under a nitrogen atmosphere to conduct polymerization. After the dropwise addition, the mixture was held at 160°C for 30 minutes and then depressurized to 8 kPa for 30 minutes. The pressure was returned to normal and the temperature was increased to 200°C at 2°C / min. Tin(II) di(2-ethylhexanoate) and gallic acid (3,4,5-trihydroxybenzoic acid) were added, and the condensation polymerization reaction was carried out at 235°C for 6 hours. After cooling to 180°C, dodecenyl succinic anhydride was added, the temperature was raised from 180°C to 210°C, and the reaction was carried out at 210°C and 20 kPa until the softening point shown in Table 1 was reached, to obtain resin f.

[0084] Comparative Example 3 (Resin g) The BPA-PO and BPA-EO listed in Table 1 were placed in a 5-liter four-neck flask equipped with a thermometer, stainless steel stirrer, downflow condenser, and nitrogen inlet tube and heated to 100°C. Terephthalic acid and dodecenyl succinic anhydride were added at 100°C, and the temperature was increased to 160°C at 2°C / min. A mixture of styrene, 2-ethylhexyl acrylate, acrylic acid, and dibutyl peroxide was added dropwise over 1.5 hours at 160°C under a nitrogen atmosphere to conduct polymerization. After the dropwise addition, the temperature was maintained at 160°C for 30 minutes, then the temperature was increased to 200°C at 2°C / min and the pressure was reduced to 200°C at 8 kPa for 30 minutes. The pressure was returned to normal and tin(II) di(2-ethylhexanoate) and gallic acid (3,4,5-trihydroxybenzoic acid) were added at 200°C. The temperature was increased to 235°C at 2°C / min and the condensation polymerization reaction was conducted at 235°C for 5 hours. After cooling to 210°C, trimellitic anhydride was added and the mixture was kept at 210°C for 1 hour, and then reacted at 210°C and 8 kPa until the softening point shown in Table 1 was reached, to obtain resin g.

[0085] Comparative example 4 (resin h) The BPA-PO and ethylene glycol listed in Table 1 were placed in a 5-liter four-neck flask equipped with a thermometer, a stainless steel stirrer, a dehydration tube equipped with a fractionating column through which hot water was passed at 98°C, and a nitrogen inlet tube, and heated to 100°C. Terephthalic acid was added at 100°C, and the temperature was increased to 165°C at 2°C / min. A mixture of styrene, n-butyl acrylate, and dibutyl peroxide was added dropwise over 1.5 hours at 165°C under a nitrogen atmosphere to carry out polymerization. After the dropwise addition, the mixture was maintained at 165°C for 30 minutes, after which tin(II) di(2-ethylhexanoate) and gallic acid (3,4,5-trihydroxybenzoic acid) were added, and the temperature was increased to 220°C at 2°C / h. The condensation polymerization reaction was carried out at 220°C for 5 hours. After cooling to 180°C, dodecenyl succinic anhydride was added, the temperature was raised from 180°C to 220°C, and the reaction was carried out at 220°C and 20 kPa until the softening point shown in Table 1 was reached, to obtain resin h.

[0086] [Table 1]

[0087] [Production of asphalt composition] Example 11 (Production of Asphalt Composition 11) 50 g of polymer-modified asphalt H type (Senaphalt, manufactured by Nisshin Seiki Co., Ltd.) was weighed into a 300 mL stainless steel container and stirred at 300 rpm with a propeller while heating to 180°C. After stirring for 10 minutes, 2.5 g of asphalt modifier A was added, and the mixture was stirred for 30 minutes to obtain asphalt composition 11. The water content in asphalt composition 11 was 0.1 mass% or less. One to two drops of the above-mentioned asphalt composition 11 were placed on a glass slide, which was then covered with a cover glass and left to stand for 3 minutes in a dryer at 180° C. After confirming that the asphalt composition 11 sandwiched between the glass slide and the cover glass had spread and an asphalt coating had been formed on the glass slide, the cover glass was immediately removed.

[0088] Examples 12 to 14 and Comparative Examples 11 to 15 (Production of Asphalt Compositions 12 to 14 and c11 to c15) Asphalt compositions 12 to 14 and c11 to c15 were produced in the same manner as in Example 11, except that the type and amount of asphalt modifier were as shown in Table 2. Each asphalt composition was used to form an asphalt coating on a glass slide.

[0089] [evaluation] The asphalt coatings obtained from the asphalt compositions were evaluated as follows, and the results are shown in Table 2.

[0090] [Evaluation of Dispersibility of Polyester Resin] The morphology of the asphalt coating on the glass slide was observed under bright-field observation with a microscope (DSX1000, manufactured by Olympus Corporation) at a magnification of 120x. This morphology photograph was imported into image analysis software (OLYMPUS Stream, manufactured by Olympus Corporation) and the image was segmented. Specifically, a threshold value was set and a binarization process was performed to separate the polyester resin particles dispersed from the asphalt base, and the average dispersed particle size was determined using the software. The measurement count in one visual field was selected to be 500 to 5000 points, and the average dispersed particle diameter of the three visual fields was taken as the average dispersed particle diameter of the polyester resin.

[0091] [Weather resistance test] The asphalt coating on the slide glass obtained in each example and comparative example was measured using a Super Xenon Weather Meter SX75 (manufactured by Suga Test Instruments Co., Ltd.) with a UV intensity of 150 W / m 2 The sample was irradiated with ultraviolet light at a wavelength of 300 to 400 nm, at a chamber temperature of 40°C, and at a humidity of 75%. The slide glass was attached around the lamp to ensure uniform irradiation of the ultraviolet light, and was rotated while being irradiated with ultraviolet light for 100 hours. This was used as the sample after ultraviolet irradiation. For the measurements (1) and (2) below, samples before and after ultraviolet irradiation were used.

[0092] (1) Pencil hardness measurement The pencil hardness was measured using a pencil scratch tester (manufactured by TP Giken Co., Ltd.) according to JIS K5600-5-4:1990. An asphalt coating formed on a glass slide was scratched with the tester using gradually decreasing hardness pencils, starting with the hardest 9H pencil. The scratches were observed using a microscope (DSX1000 manufactured by Olympus Corporation), and the pencil hardness at which the coating was scraped and the glass was exposed was determined. The highest pencil hardness at which the coating was scraped and the glass was not exposed was taken as the pencil hardness of the asphalt coating. For example, if the glass was exposed by scraping with 4H, but not by 3H, the pencil hardness of the asphalt coating was considered to be 3H.

[0093] (2) FT-IR measurement (calculation of carbonyl index increment) FT-IR measurements were performed using an instrument manufactured by Thermo Fisher Scientific Inc. Measurements were performed using samples before and after UV irradiation, and the carbonyl indices (I) and (II) below were calculated from the obtained absorption peak curves. The carbonyl index increment was then calculated using the following formula. A larger carbonyl index increment indicates more deterioration of the asphalt coating, and a smaller carbonyl index increment indicates better weather resistance. Carbonyl index increment = Carbonyl index (II) / Carbonyl index (I) Carbonyl Index (II): 1700 cm of sample after UV irradiation -1 absorbance / 1600cm -1 absorbance of Carbonyl index (I): 1700 cm of the sample before UV irradiation -1 absorbance / 1600cm -1 absorbance of

[0094] [Table 2]

[0095] As is clear from Table 2, the asphalt coatings produced using the asphalt compositions of the present invention, which contain the asphalt modifiers of the present invention, have pencil hardnesses of F or higher even after ultraviolet irradiation, and the increase in the carbonyl index is small, indicating that they have excellent weather resistance (Examples 11 to 14). In contrast, the asphalt coating using resin e as an asphalt modifier that does not have structural units derived from styrene-based compounds or structural units derived from bireactive monomers (Comparative Example 11), the asphalt coating using resin f with a weight-average molecular weight of more than 30,000 as an asphalt modifier (Comparative Example 12), the asphalt coatings using resins g and h that do not have structural units derived from PET (Comparative Examples 13 and 14), and the asphalt coating that does not use an asphalt modifier (Comparative Example 15) all have poor weather resistance.

Claims

1. An asphalt modifier containing a polyester resin, An asphalt modifier, wherein the polyester-based resin is a composite resin containing a polyester resin segment containing a structural unit derived from an alcohol component, a structural unit derived from a carboxylic acid component, and a structural unit derived from polyethylene terephthalate, a vinyl-based resin segment containing a structural unit derived from a styrene-based compound, and a structural unit derived from a bireactive monomer, and the weight-average molecular weight of the polyester-based resin is 30,000 or less.

2. The asphalt modifier according to claim 1, wherein the structural units derived from the alcohol component include structural units derived from an alkylene oxide adduct of bisphenol A.

3. The structural unit derived from the carboxylic acid component comprises a structural unit derived from terephthalic acid, a structural unit derived from dodecenyl succinic acid, a structural unit derived from trimellitic acid, and at least one selected from a structural unit derived from adipic acid. The asphalt modifier according to claim 1 or 2.

4. The asphalt modifier according to claim 1 or 2, wherein the weight average molecular weight of the polyester resin is 7,000 or more.

5. An asphalt composition comprising asphalt and the asphalt modifier according to claim 1 or 2.

6. 6. The asphalt composition of claim 5, wherein the asphalt is a polymer-modified asphalt H type.

7. The asphalt composition according to claim 5, wherein the water content in the asphalt composition is 0.5 mass% or less.

8. The asphalt composition according to claim 5, which is for paving purposes.

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