Asphalt modifying material

Abstract

To provide an asphalt modifying material that enables production of an asphalt mixture resistant to scattering of aggregate and exhibiting favorable adhesion between aggregates with superior abrasion resistance, even under continuous impact load on asphalt pavement caused by running vehicles, and also provide an asphalt composition and an asphalt mixture using the asphalt modifying material.SOLUTION: An asphalt modifying material comprising a polyester resin and an olefin resin, the olefin resin being a polyolefin having no functional group, the content of the olefin resin being 0.03 pt.mass or more and 6.00 pts.mass or less relative to 100 pts.mass of the polyester resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an asphalt modifier, an asphalt composition, and an asphalt mixture. [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 describes an asphalt binder that includes straight asphalt and a thermoplastic resin, with the thermoplastic resin content being 15% by mass or more, with the aim of providing an asphalt binder that enables paving with excellent dynamic stability and is less likely to bleed out from the asphalt mixture for paving. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 032609 Summary of the Invention [Problem to be solved by the invention]

[0005] Asphalt pavements are continuously subjected to impact loads from passing vehicles. Therefore, if the adhesion between aggregates in the asphalt mixture via the asphalt binder is insufficient, the continuous impact load can cause aggregate to scatter from the pavement surface of roads paved with the asphalt mixture. However, the asphalt mixture obtained using the asphalt binder described in Patent Document 1 may not be able to sufficiently prevent aggregate from scattering from the pavement surface. The present invention relates to an asphalt modifier that can produce an asphalt mixture that is resistant to aggregate scattering, has good adhesion between aggregates, and has excellent abrasion resistance even when an impact load is continuously applied to an asphalt pavement by a traveling vehicle, and to an asphalt composition and asphalt mixture that use the asphalt modifier. [Means for solving the problem]

[0006] The present inventors have discovered that in an asphalt modifier containing a polyester resin and an olefin-based resin, the olefin-based resin is a polyolefin having no functional groups, and that the above-mentioned problems can be solved by controlling the content of the olefin-based resin within a specific range. That is, the present invention includes the following [1] to [3]. [1] An asphalt modifier containing a polyester resin and an olefin resin, An asphalt modifier, wherein the olefin-based resin is a polyolefin having no functional groups, and the content of the olefin-based resin is 0.03 parts by mass or more and 6.00 parts by mass or less per 100 parts by mass of the polyester resin. [2] An asphalt composition containing asphalt and the asphalt modifier according to [1], An asphalt composition, in which the content of the olefin-based resin is 0.003 parts by mass or more and 0.500 parts by mass or less per 100 parts by mass of the total content of the asphalt, olefin-based resin, and polyester resin. [3] [2] An asphalt mixture comprising the asphalt composition according to the present invention and aggregate. [Effects of the Invention]

[0007] The present invention provides an asphalt modifier that can produce an asphalt mixture that is resistant to aggregate scattering, has good adhesion between aggregates, and has excellent abrasion resistance even when an impact load is continuously applied to an asphalt pavement by a traveling vehicle, as well as an asphalt composition and asphalt mixture that use the asphalt modifier. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Asphalt modifier] The asphalt modifier of the present invention contains a polyester resin and an olefin resin, the olefin resin being a polyolefin having no functional groups, and the content of the olefin resin per 100 parts by mass of the polyester resin is 0.03 parts by mass or more and 6.00 parts by mass or less. By using an asphalt composition using the asphalt modifier of the present invention as a binder in an asphalt mixture, it is possible to maintain good adhesion between aggregates, prevent aggregate from scattering due to impact loads, and obtain an asphalt mixture with excellent abrasion resistance.

[0009] The reason why the present invention has an effect is not clear, but is thought to be as follows. The asphalt modifier of the present invention contains a polyester resin and a small amount of an olefin resin without functional groups. It is believed that the small amount of olefin resin, which does not affect the compatibility of asphalt and polyester resin, is present at the aggregate interface together with the polyester resin in the asphalt mixture. This is believed to impart impact absorption properties to the asphalt mixture in addition to the asphalt mixture modifying effects of the polyester resin, such as improved rutting resistance. As a result, it is believed that an asphalt mixture using an asphalt composition obtained using the asphalt modifier of the present invention as a binder can maintain good adhesion between aggregates and is less likely to scatter aggregates due to impact loads.

[0010] The definitions of various terms used in this specification are shown below. By "functional group" is meant epoxy groups, carboxy groups, hydroxy groups, amino groups and amide groups. Whether a resin is crystalline or amorphous is determined by its crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the endothermic maximum peak temperature (softening point (°C) / endothermic maximum peak temperature (°C)) measured by the method described in the Examples below. A crystalline resin is one with a crystallinity index of 0.6 or more and 1.4 or less. An amorphous resin is one in which no endothermic peak is observed, or, if an endothermic peak is observed, one with a crystallinity index of less than 0.6 or more than 1.4. The crystallinity index can be adjusted appropriately by adjusting the types and ratios of raw material monomers, as well as production conditions such as reaction temperature, reaction time, and cooling rate. In the polyester resin, a "structural unit derived from an alcohol component" means a structure in which a hydrogen atom is removed from a hydroxy group of an alcohol component, and a "structural unit derived from a carboxylic acid component" means a structure in which a hydroxy group is removed from a carboxy group of a carboxylic acid component. The term "carboxylic acid component" 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 resin is a polycondensation product of an alcohol component and a carboxylic acid component, and contains structural units derived from an alcohol component and structural units derived from a carboxylic acid component. The polyester resin may be an amorphous polyester resin or a crystalline polyester resin, and is preferably an amorphous polyester resin. The alcohol component, the carboxylic acid component, and the physical properties of the polyester resin will be described below.

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

[0013] The chain aliphatic diol is preferably a linear or branched chain aliphatic diol having from 2 to 12 carbon atoms in the main chain, more preferably a linear or branched chain aliphatic diol having from 2 to 8 carbon atoms in the main chain, and even more preferably a linear or branched chain aliphatic diol having from 2 to 4 carbon atoms in the main chain. The chain aliphatic diol is preferably a saturated chain aliphatic diol. Specific examples of the chain aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,10-decanediol, and 1,12-dodecanediol.

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

[0015] Examples of aromatic diols include bisphenol A (2,2-bis(4-hydroxyphenyl)propane) and alkylene oxide adducts of bisphenol A. Examples of alkylene oxide adducts of bisphenol A include alkylene oxide adducts of bisphenol A represented by the following formula (I):

[0016] [ka]

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

[0018] Examples of the alkylene oxide adduct of bisphenol A represented by formula (I) include a propylene oxide adduct of bisphenol A and an ethylene oxide adduct of bisphenol A. These alkylene oxide adducts of bisphenol A can be used alone or in combination of two or more.

[0019] The trihydric or higher polyhydric alcohol is preferably a trihydric alcohol, and examples of the trihydric or higher polyhydric alcohol include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0020] The alcohol component may further contain a monohydric aliphatic alcohol from the viewpoint of adjusting physical properties. Examples of the monohydric aliphatic alcohol include lauryl alcohol, myristyl alcohol, palmityl alcohol, and stearyl alcohol. These monohydric aliphatic alcohols may be used alone or in combination of two or more.

[0021] (carboxylic acid component) Examples of the carboxylic acid component include aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and polycarboxylic acids having a valence of 3 to 6. These carboxylic acid components can be used alone or in combination of two or more.

[0022] The aliphatic dicarboxylic acid preferably has 4 or more carbon atoms in the main chain and preferably 10 or less, more preferably 8 or less, and even more preferably 6 or less, such as fumaric acid, maleic acid, oxalic acid, malonic acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, or anhydrides or alkyl esters thereof (e.g., alkyl groups having 1 to 3 carbon atoms). Examples of substituted succinic acids include dodecylsuccinic acid, dodecenylsuccinic acid, and octenylsuccinic acid. Succinic acid substituted with an alkyl group having from 1 to 20 carbon atoms or an alkenyl group having from 2 to 20 carbon atoms, or an anhydride thereof, can be produced, for example, according to the description in JP-A-2008-145712. Alternatively, commercially available products can also be used.

[0023] Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, anhydrides thereof, and alkyl esters thereof (for example, alkyl groups having 1 to 3 carbon atoms). Of the above aromatic dicarboxylic acids, isophthalic acid and terephthalic acid are preferred, with terephthalic acid being more preferred, from the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates.

[0024] The trivalent or more and hexavalent polycarboxylic acid is preferably a trivalent carboxylic acid. Examples of the trivalent or more and hexavalent polycarboxylic acid include trimellitic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, and acid anhydrides thereof.

[0025] The carboxylic acid component may further contain a monovalent aliphatic carboxylic acid from the viewpoint of adjusting physical properties. Examples of the monovalent aliphatic carboxylic acid include monovalent aliphatic carboxylic acids having from 12 to 20 carbon atoms, such as lauric acid, myristic acid, palmitic acid, stearic acid, and alkyl (having from 1 to 3 carbon atoms) esters of these acids. These monovalent aliphatic carboxylic acids may be used alone or in combination of two or more.

[0026] (Structural unit derived from polyethylene terephthalate) The polyester resin preferably contains a polycondensate of an alcohol component, a carboxylic acid compound, and polyethylene terephthalate (PET). The polyethylene terephthalate may contain small amounts of components such as butanediol and isophthalic acid in addition to structural units derived from ethylene glycol and terephthalic acid. The polyethylene terephthalate is preferably recycled polyethylene terephthalate. When the polyester resin contains structural units consisting of ethylene glycol and terephthalic acid derived from polyethylene terephthalate, the "structural units derived from alcohol components" include structural units derived from ethylene glycol derived from polyethylene terephthalate, and the "structural units derived from carboxylic acid components" include structural units derived from terephthalic acid derived from polyethylene terephthalate.

[0027] (Preferred embodiment of polyester resin) In a preferred embodiment of the polyester resin, when the structural units derived from the alcohol component include structural units derived from an aromatic diol, the content of the structural units derived from the aromatic diol in 100 mol% of the structural units derived from the alcohol component is preferably 10 mol% or more and 70 mol% or less, more preferably 20 mol% or more, even more preferably 30 mol% or more, even more preferably 40 mol% or more, and more preferably 60 mol% or less, even more preferably 50 mol% or less. In a preferred embodiment of the polyester resin, when the structural units derived from the alcohol component include structural units derived from an aromatic diol, the content of structural units derived from an aliphatic diol in 100 mol% of structural units derived from the alcohol component is preferably 30 mol% or more and 90 mol% or less, more preferably 40 mol% or more, even more preferably 50 mol% or more, and more preferably 80 mol% or less, even more preferably 70 mol% or less, and even more preferably 60 mol% or less. In a preferred embodiment of the polyester resin, when the structural units derived from the alcohol component do not contain structural units derived from an aromatic diol, the content of structural units derived from an aliphatic diol in 100 mol % of structural units derived from the alcohol component is 100 mol %. In a preferred embodiment of the polyester resin, the content of structural units derived from aromatic dicarboxylic acids in 100 mol% of structural units derived from carboxylic acid components is preferably 50 mol% or more and 98 mol% or less, more preferably 60 mol% or more, even more preferably 70 mol% or more, even more preferably 80 mol% or more, and more preferably 95 mol% or less, even more preferably 90 mol% or less. In a preferred embodiment of the polyester resin, the content of structural units derived from aliphatic dicarboxylic acids in 100 mol% of structural units derived from carboxylic acid components is preferably 1 mol% or more and 20 mol% or less, more preferably 4 mol% or more, even more preferably 7 mol% or more, and more preferably 18 mol% or less, even more preferably 15 mol% or less. In a preferred embodiment of the polyester resin, the content of the alcohol component, the carboxylic acid compound, and the polycondensate of polyethylene terephthalate (PET) in the polyester resin is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more, and 100% by mass or less, from the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates.

[0028] (Physical properties of polyester resin) From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, 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 obtaining an asphalt mixture that can maintain good adhesion between aggregates, the glass transition point of the polyester resin is preferably 30°C or higher and 95°C or lower, more preferably 40°C or higher, even more preferably 50°C or higher, and more preferably 85°C or lower, even more preferably 75°C or lower, and even more preferably 65°C or lower. From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the acid value of the polyester resin is preferably 1 mgKOH / g or more and 30 mgKOH / g or less, more preferably 3 mgKOH / g or more, even more preferably 5 mgKOH / g or more, and more preferably 25 mgKOH / g or less, even more preferably 20 mgKOH / g or less. From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the hydroxyl value of the polyester resin is preferably 1 mgKOH / g or more and 40 mgKOH / g or less, more preferably 10 mgKOH / g or more, even more preferably 15 mgKOH / g or more, and more preferably 35 mgKOH / g or less, even more preferably 30 mgKOH / g or less.

[0029] The softening point, glass transition point, acid value, and hydroxyl value of the polyester resin can be measured by the methods described in the Examples. The softening point, glass transition point, acid value, and hydroxyl value can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0030] The polyester resin may be modified to such an extent that its properties are not substantially impaired. Specific examples of modified polyester resins include polyester resins grafted or blocked with phenol, urethane, epoxy, or the like, by methods described in JP-A-11-133668, JP-A-10-239903, JP-A-8-20636, etc. A preferred modified polyester resin is a urethane-modified polyester resin obtained by urethane-extending a polyester resin with a polyisocyanate compound.

[0031] (Method of producing polyester resin) The polyester resin can be produced, for example, by polycondensing the alcohol component and the carboxylic acid component described above. The temperature of the polycondensation reaction adjusts the reactivity and is preferably 150°C or higher and 260°C or lower, more preferably 160°C or higher, even more preferably 170°C or higher, and more preferably 250°C or lower, even more preferably 240°C or lower.

[0032] When the polyester resin contains structural units derived from ethylene glycol derived from polyethylene terephthalate and structural units derived from terephthalic acid derived from polyethylene terephthalate, the amount of polyethylene terephthalate present in the raw material is preferably 5% by mass or more and 55% by mass or less, more preferably 15% by mass or more, even more preferably 25% by mass or more, and more preferably 45% by mass or less, even more preferably 35% by mass or less, of the total amount of polyethylene terephthalate, alcohol component, and carboxylic acid component. By adding polyethylene terephthalate during the polycondensation reaction between the alcohol component and the carboxylic acid component, an ester exchange reaction occurs, and a polyester resin can be obtained in which structural units derived from polyethylene terephthalate are incorporated into structural units derived from the alcohol component and structural units derived from the carboxylic acid component. Polyethylene terephthalate may be present from the start of the polycondensation reaction or may be added to the reaction system during the polycondensation reaction. The timing of adding polyethylene terephthalate is when the reaction rate between the alcohol component and the carboxylic acid component is 10% or less, and more preferably 5% or less. The reaction rate refers to the value of the amount of reaction water produced (moles) / the theoretical amount of water produced (moles) × 100.

[0033] In view of the reaction rate, an esterification catalyst can be used in the polycondensation reaction. Examples of the esterification catalyst include tin(II) compounds that do not have a Sn-C bond, such as tin(II) di(2-ethylhexanoate). From the viewpoint of the reaction rate, the amount of the esterification catalyst used is preferably 0.01 to 2.0 parts by mass, more preferably 0.1 to 100 parts by mass of the raw material monomer, even more preferably 0.2 to 100 parts by mass of the raw material monomer, and more preferably 1.5 to 100 parts by mass of the raw material monomer. In addition to the esterification catalyst, an esterification promoter can be used in the polycondensation reaction. Examples of the esterification promoter include pyrogallol compounds such as gallic acid. The amount of the esterification promoter used is preferably 0.001 to 0.20 parts by mass, more preferably 0.005 to 0.01 parts by mass, even more preferably 0.01 to 0.15 parts by mass, and even more preferably 0.10 to 0.10 parts by mass, relative to 100 parts by mass of the raw material monomer.

[0034] (Polyester resin content in asphalt modifier) The content of the 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, and even more preferably 90% by mass or more, of the total mass of the asphalt modifier.

[0035] <Olefin resin> The olefin resin is a polyolefin having no functional groups. The polyolefin is preferably a hydrocarbon, and is preferably a homopolymer of an α-olefin such as ethylene, propylene, or butene, or a copolymer thereof. From the viewpoint of obtaining an asphalt mixture capable of maintaining good adhesion between aggregates, at least one selected from polyethylene and polypropylene is preferred, and polyethylene is more preferred. Specific examples of polyethylene include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), ultra-low-density polyethylene (ULDPE), and linear low-density polyethylene (LLDPE). From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, at least one selected from LLDPE, LDPE, and HDPE is preferred, at least one selected from LLDPE and LDPE is more preferred, and LLDPE is even more preferred. The polypropylene may be a homopolymer of propylene or a copolymer of propylene and an α-olefin. The copolymer of propylene and an α-olefin may be polymerized in a random or block manner. The number of carbon atoms in the α-olefin is preferably from 2 to 18. Specific examples of the α-olefin include ethylene, propylene, butene, pentene, hexene, heptene, octene, and nonene. The content of propylene-derived structural units in the copolymer of propylene and α-olefin is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, and 99% by mass or less.

[0036] (Physical properties of olefin resins) The melt mass-flow rate (MFR) of the olefin resin is preferably 0.01 g / 10 min or more and 50 g / 10 min or less, and from the viewpoint of solubility in asphalt, it is more preferably 0.1 g / 10 min or more, and even more preferably 0.5 g / 10 min or more, and from the viewpoint of impact absorption, it is more preferably 20 g / 10 min or less, even more preferably 10 g / 10 min or less, and even more preferably 5 g / 10 min or less. The melt mass-flow rate of an olefin resin is a value measured in accordance with JIS K7210-1:2014. For example, the melt mass-flow rate of polyethylene is measured at 190°C under a load of 2.16 kg. The melt mass-flow rate of polypropylene is measured at 230°C under a load of 2.16 kg.

[0037] (Olefin resin content in asphalt modifier) From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the content of the olefin resin in the asphalt modifier is 0.03 parts by mass or more and 6.00 parts by mass or less, preferably 0.10 parts by mass or more, more preferably 0.30 parts by mass or more, more preferably 0.80 parts by mass or more, and preferably 3.00 parts by mass or less, more preferably 2.00 parts by mass or less, more preferably 1.80 parts by mass or less, per 100 parts by mass of polyester resin.

[0038] 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.

[0039] [Asphalt composition] The asphalt composition of the present invention contains asphalt and the asphalt modifier described above. That is, the asphalt composition of the present invention contains asphalt and the polyester resin and olefin resin that constitute the asphalt modifier described above.

[0040] <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, with polymer-modified asphalt being more preferred from the viewpoint of durability of the asphalt pavement, and straight asphalt being more preferred from the viewpoint of versatility.

[0041] (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.

[0042] 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.

[0043] The total content of straight asphalt and 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.

[0044] (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 25 parts by mass or less, more preferably 1 part by mass or more, even more preferably 4 parts by mass or more, even more preferably 7 parts by mass or more, and more preferably 21 parts by mass or less, even more preferably 17 parts by mass or less, even more preferably 13 parts by mass or less, per 100 parts by mass of asphalt.

[0045] (Content of olefin resin in asphalt composition) From the viewpoint of obtaining an asphalt mixture that can maintain good adhesion between aggregates, the content of the olefin-based resin per 100 parts by mass of the total content of asphalt, polyester resin, and olefin-based resin that make up the asphalt composition is preferably 0.003 parts by mass or more and 0.500 parts by mass or less, more preferably 0.010 parts by mass or more, even more preferably 0.030 parts by mass or more, and more preferably 0.350 parts by mass or less, even more preferably 0.200 parts by mass or less, and even more preferably 0.150 parts by mass or less.

[0046] <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.

[0047] [Method for producing asphalt composition] The asphalt composition of the present invention can be produced by mixing asphalt with the polyester resin and olefin-based resin. Specifically, the asphalt is heated and melted, the polyester resin and olefin-based resin are added, and the mixture is stirred and mixed in a commonly used mixer until the polyester resin and olefin-based resin are uniformly dispersed in the asphalt, thereby obtaining the asphalt composition. The polyester resin and olefin-based resin may be added simultaneously or sequentially. 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.

[0048] The mixing temperature of the asphalt, polyester resin, and olefin resin 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 and olefin resin in the asphalt. Furthermore, the mixing time for the asphalt, polyester resin, and olefin resin is preferably 15 minutes or more, more preferably 30 minutes or more, and even more preferably 1 hour or more, from the viewpoint of uniformly dispersing the polyester resin and olefin resin in the asphalt, and is preferably 10 hours or less, more preferably 5 hours or less, and even more preferably 3 hours or less. 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 with the asphalt, polyester resin, and olefin resin that constitute the asphalt composition to form an asphalt mixture. In other words, the asphalt composition of the present invention is suitable for paving, and particularly suitable for road paving.

[0049] [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, i.e., the asphalt mixture contains at least aggregate, asphalt, and the polyester resin and olefin resin.

[0050] <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.

[0051] <Additives> In addition to the aggregate, asphalt, polyester resin, and olefin 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.

[0052] [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, examples include a method in which the above-mentioned asphalt composition is added to heated aggregate and mixed therewith, and a method in which the asphalt, polyester resin, and olefin resin constituting the above-mentioned asphalt composition are added to heated aggregate and mixed therewith.

[0053] 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.

[0054] The mixing temperature of the aggregate with the asphalt, polyester resin, and olefin resin that make up the 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 with the asphalt, polyester resin, and olefin resin that make up 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.

[0055] 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 with asphalt, polyester resin, and olefin-based resin that constitute the 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.

[0056] [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 is mixed with asphalt, polyester resin, and olefin resin that constitute the asphalt composition, are used for paving. The road paving method includes the steps of applying the asphalt mixture described above to a paving target 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; or mixing the asphalt, polyester resin, and olefin resin that constitute the asphalt composition with heated aggregate to obtain an asphalt mixture (Step 1); and applying the asphalt mixture obtained in Step 1 to the paving target to form an asphalt pavement layer (Step 2). The asphalt pavement layer is preferably a base layer or a surface layer.

[0057] 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.

[0058] The present invention includes the following aspects. <1> An asphalt modifier containing a polyester resin and an olefin resin, An asphalt modifier, wherein the olefin-based resin is a polyolefin having no functional groups, and the content of the olefin-based resin is 0.03 parts by mass or more and 6.00 parts by mass or less per 100 parts by mass of the polyester resin. <2> The melt mass flow rate of the olefin resin is 0.01 g / 10 min or more and 50 g / 10 min or less. <1> The asphalt modifier according to claim 1. <3> The olefin-based resin is at least one selected from polyethylene and polypropylene. <1> or <2> The asphalt modifier according to claim 1. <4> The olefin resin is polyethylene. <1> ~ <3> The asphalt modifier according to any one of the above. <5> The olefin-based resin is at least one selected from linear low-density polyethylene and low-density polyethylene. <1> ~ <4> The asphalt modifier according to any one of the above. <6> Asphalt and <1> ~ <5> An asphalt composition containing the asphalt modifier according to any one of the preceding claims, An asphalt composition having an olefin resin content of 0.003 parts by mass or more and 0.500 parts by mass or less per 100 parts by mass of the total content of asphalt, olefin resin, and polyester resin. <7> <6> An asphalt mixture comprising the asphalt composition according to claim 1 and aggregate. [Example]

[0059] 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.

[0060] The physical properties of the polyester resin and the olefin resin were measured and evaluated by the following methods. [Measurement method] [Softening point, crystallinity index and glass transition point of polyester resin] (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) Crystallinity index Using a differential scanning calorimeter "Q100" (TA Instruments Japan), 0.02 g of sample was weighed into an aluminum pan and cooled to 0°C at a rate of 10°C / min. The sample was then left to stand for 1 minute, after which it was heated to 180°C at a rate of 10°C / min and the calorific value was measured. The temperature of the endothermic peak with the largest area was defined as the endothermic maximum peak temperature (1), and the crystallinity index was calculated by (softening point (°C)) / (endothermic maximum peak temperature (1) (°C)). (3) Glass transition temperature Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.01-0.02 g of sample was weighed into an aluminum pan, heated to 200 °C, and cooled to 0 °C at a rate of 10 °C / min. Measurements were then performed while the temperature was increased to 150 °C at a rate of 10 °C / min. The temperature of the endothermic peak with the largest peak area was determined as the endothermic maximum peak temperature (2). The glass transition temperature was determined as the temperature at the intersection of the extended line of the baseline below the endothermic maximum peak temperature (2) and the tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0061] [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)).

[0062] [Melt mass flow rate of olefin resin] The melt mass flow rate of the olefin resin was measured at 190°C under a load of 2.16 kg in accordance with JIS K7210-1:2014.

[0063] Production Example 1 (Production of Polyester Resin A1) The alcohol components listed in Table 1 were 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 at 100°C, the flask was heated to 220°C at 0.5°C / min. Polyethylene terephthalate (PET) was added at 220°C and then heated to 235°C at 0.5°C / min. Under a nitrogen atmosphere, tin(II) di(2-ethylhexanoate) and gallic acid were added at 235°C. Polycondensation reaction was carried out at 235°C for 6 hours. After cooling to 180°C, branched alkenyl succinic anhydride was added. The temperature was increased from 180°C to 220°C at 0.3°C / min. The reaction was continued at 220°C and 20 kPa until the softening point listed in Table 1 was reached, yielding Polyester Resin A1.

[0064] Production Example 2 (Production of Polyester Resin A2) The alcohol components listed in Table 1 were 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. At 100°C, 34 g of adipic acid was added, and the temperature was raised to 180°C at 2.0°C / min. After reaching 180°C, a condensation polymerization reaction was carried out for 2 hours. At 180°C, terephthalic acid and PET were added, and the temperature was raised to 235°C at 2.0°C / min. Under a nitrogen atmosphere, tin(II) di(2-ethylhexanoate) and gallic acid were added at 235°C and a condensation polymerization reaction was carried out for 6 hours at 235°C. After cooling to 180°C, 172 g of adipic acid was added. The temperature was raised from 180°C to 210°C at 0.3°C / min, and the reaction was continued at 210°C and 8 kPa until the softening point listed in Table 1 was reached, yielding Polyester Resin A2.

[0065] Production Example 3 (Production of Polyester Resin A3) The alcohol components shown in Table 1 were 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. Branched alkenyl succinic anhydride (90 g) was added at 100°C, and the temperature was raised to 180°C at 0.5°C / min. After reaching 180°C, a condensation polymerization reaction was carried out for 2 hours. Terephthalic acid and PET were added at 180°C, and the temperature was raised to 180°C at 0.5°C / min. Under a nitrogen atmosphere, tin(II) di(2-ethylhexanoate) and gallic acid were added at 180°C, and the temperature was raised to 235°C at 0.5°C / min. After reaching 235°C, a condensation polymerization reaction was carried out for 8 hours. After cooling to 180°C, branched alkenyl succinic anhydride (360 g) was added. The temperature was raised from 180°C to 220°C at a rate of 0.3°C / min, and the reaction was carried out at 220°C and 8 kPa until the softening point shown in Table 1 was reached, to obtain polyester resin A3.

[0066] [Table 1]

[0067] Example 1 200 g of Toyoura standard sand (manufactured by Toyoura Silica Mining Co., Ltd.) heated at 180°C for at least 6 hours in a thermostatic bath was placed in a 200 mL SUS beaker placed on a hot plate, and while stirring at 100 rpm with a disc turbine-type stirring blade, 10 g of straight asphalt 60-80 (manufactured by Mitsubishi Corporation Energy Corporation) heated to 180°C, 1 g of polyester resin A1, and 0.01 g of SIGMA-ALDRICH polyethylene (linear-low density, melt flow rate 1.0 g / 10 min) were added and mixed at 180°C for 1 minute to obtain asphalt mixture AS-1.

[0068] Examples 2 to 14, Comparative Examples 1 and 2 Asphalt mixtures AS-2 to AS-14 and AS'-1 to AS'-2 were obtained in the same manner as in Example 1, except that the polyester resins and olefin-based resins shown in Table 2 were used in the amounts shown in Table 2.

[0069] <Scratching test> The asphalt mixture immediately after being obtained was quickly and evenly spread over the entire surface of an AS ONE test piece (a slate board 150 mm long, 70 mm wide, and 4.0 mm thick) using a metal spatula, and was then left to stand until it reached room temperature (25°C), creating a layer of asphalt mixture. The abrasion test was carried out using an AB-201 Sutherland type Ink Lab Tester manufactured by Tester Sangyo Co., Ltd. The load was 0.31 kg / cm. 2 (Base 908g + weight 3090g, friction surface 2.54cm x 5.08cm) TRUSCO sheet paper #40 was fixed to the friction surface. The abrasion tester and the slate board coated with the asphalt mixture were left to stand in a constant temperature room at 5°C for at least 6 hours, after which the abrasion test was carried out 1000 times at 5°C, the mass of the asphalt mixture was measured, and the residual rate was calculated using the following formula to evaluate aggregate scattering. A higher residual rate means that the aggregate is less likely to scatter and the asphalt mixture has good adhesion between the aggregates. If the slate surface was exposed before 1000 times, the evaluation was deemed impossible at that point. Residual rate (%) = 100 x mass of asphalt mixture after abrasion test / mass of asphalt mixture before abrasion test after leaving it in a constant temperature room at 5°C for 6 hours or more

[0070] [Table 2]

[0071] The results in Table 2 show that the asphalt mixture of the present invention is less likely to scatter aggregates even when subjected to continuous impact loads, and the adhesion between the aggregates is good (Examples 1 to 14). In contrast, in the asphalt mixture produced without using the olefin resin, the slate surface was exposed before being rubbed 1,000 times in the rub test, indicating poor adhesion between the aggregates (Comparative Example 1).The asphalt mixture produced using an olefin resin content of more than 6.00 parts by mass (6.50 parts by mass) per 100 parts by mass of polyester resin indicated poor adhesion between the aggregates (Comparative Example 2).

Claims

1. An asphalt modifier containing a polyester resin and an olefin resin, An asphalt modifier, wherein the olefin-based resin is a polyolefin having no functional group, and the content of the olefin-based resin is 0.03 parts by mass or more and 6.00 parts by mass or less per 100 parts by mass of the polyester resin.

2. The asphalt modifier according to claim 1, wherein the melt mass flow rate of the olefin resin is 0.01 g / 10 min or more and 50 g / 10 min or less.

3. The asphalt modifier according to claim 1 or 2, wherein the olefin-based resin is at least one selected from polyethylene and polypropylene.

4. The asphalt modifier according to claim 1 or 2, wherein the olefin-based resin is polyethylene.

5. The asphalt modifier according to claim 1 or 2, wherein the olefin resin is at least one selected from linear low-density polyethylene and low-density polyethylene.

6. An asphalt composition containing asphalt and the asphalt modifier according to claim 1 or 2, An asphalt composition, wherein the content of the olefin-based resin is 0.003 parts by mass or more and 0.500 parts by mass or less per 100 parts by mass of the total content of the asphalt, the olefin-based resin, and the polyester resin.

7. An asphalt mixture comprising the asphalt composition of claim 6 and aggregate.

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