Asphalt modifier

Abstract

The present invention relates to an asphalt modifier for obtaining an asphalt mixture that forms a paved surface with excellent durability of the coating film of paving paint, a method for producing the same, an asphalt mixture containing the asphalt modifier, and a paving method. [Solution] An asphalt modifier containing a polyester comprising structural units derived from an alcohol component and structural units derived from a carboxylic acid component, wherein the structural units derived from the carboxylic acid component include structural units derived from an organic acid having a rosin-derived structure.

Description

[Technical Field]

[0001] The present invention relates to an asphalt modifier, a method for producing the same, an asphalt mixture containing the asphalt modifier, and a paving method. [Background technology]

[0002] Asphalt paving is used for roads, parking lots, freight yards, and sidewalks because it is relatively easy to lay and the time from the start of paving work to the start of traffic is short. Asphalt paving is formed by an asphalt mixture in which aggregates are bound together with asphalt, so the paved road has good hardness and durability. However, asphalt pavements deteriorate with long-term use, necessitating repairs. These repairs increase maintenance costs and significantly impact automobile traffic.

[0003] Patent Document 1 discloses an asphalt-containing material comprising an asphalt binder composition that can make an asphalt composition that delays and reduces the aging deterioration of asphalt materials, the asphalt binder comprising at least one of virgin asphalt binder, air-blown virgin asphalt binder, recycled asphalt binder material (RAP) including asphalt pavement material, or recycled asphalt binder material (RAS) including asphalt shingles; and an anti-aging agent which is a reaction product of a component comprising (i) a first material comprising a compound containing one or more carbonyl groups, and (ii) a second material that reacts with the one or more carbonyl groups of the first material to add hydroxyl groups to the reaction product, wherein the anti-aging agent contains a hydroxyl value of more than about 25 mg KOH / g. Patent Document 2 discloses a method for producing modified asphalt that facilitates the production of inexpensive modified asphalt, which involves preheating and mixing asphalt and rosin to fuse and melt them together, thereby creating a binder with high hardness and elasticity. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2024-504283 [Patent Document 2] Japanese Patent Application Publication No. 9-302233 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The asphalt-containing material described in Patent Document 1 can be used as a replacement for virgin asphalt binders in recycled pavement mixtures by delaying and reducing the aging degradation of asphalt materials. Furthermore, the manufacturing method described in Patent Document 2 can provide high-performance and inexpensive modified asphalt. However, pavements using the asphalt-containing material described in Patent Document 1 or the modified asphalt described in Patent Document 2 suffer from the problem of low durability of the coating film of the pavement paint on the pavement surface. The present invention relates to an asphalt modifier for obtaining an asphalt mixture that forms a paved surface with excellent durability of the coating film of a paving paint, a method for producing the same, an asphalt mixture containing the asphalt modifier, and a paving method. [Means for solving the problem]

[0006] The present invention relates to the following [1] to [4]. [1] An asphalt modifier containing a polyester resin that includes constituent units derived from an alcohol component and constituent units derived from a carboxylic acid component, An asphalt modifier in which the constituent units derived from the carboxylic acid component include constituent units derived from an organic acid having a rosin-derived structure. [2] An asphalt mixture containing asphalt, aggregate, and the asphalt modifier described in [1]. A paving method comprising the steps of applying the asphalt mixture described in [3] and [2] to the paving target, and forming an asphalt paving material layer. [4] A method for producing an asphalt modifier containing a polyester resin, comprising the step of polycondensing a monomer mixture containing an alcohol component and a carboxylic acid component, A method for producing an asphalt modifier, wherein the carboxylic acid component contains an organic acid having a rosin-derived structure. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an asphalt modifier and a method for producing the same for obtaining an asphalt mixture that forms a paved surface with excellent durability of the coating film of a paving paint, an asphalt mixture containing the asphalt modifier, and a paving method. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows the results of differential scanning calorimetry of polyester resin A1 manufactured in Example 1-1. [Modes for carrying out the invention]

[0009] [Asphalt modifier] The asphalt modifier of the present invention contains a polyester resin comprising structural units derived from an alcohol component and structural units derived from a carboxylic acid component. Here, the structural units derived from the carboxylic acid component include structural units derived from an organic acid having a rosin-derived structure.

[0010] The inventors have found that an asphalt mixture containing asphalt modified with the asphalt modifier of the present invention forms a paved surface with excellent durability of the coating film for paving paints. The detailed mechanism by which the effects of this invention are obtained is unknown, but some aspects may be as follows. Conventional asphalt modifiers containing polyester resin can produce asphalt mixtures that form a highly durable pavement surface by binding hydrophilic aggregates and hydrophobic asphalt. However, the coating film of pavement paints is formed by melting a thermoplastic resin such as petroleum resin containing a colorant at high temperature and applying it to the pavement material layer, or by applying and drying a water-based paint, which is made by dissolving acrylic resin containing a colorant in a solvent, onto the pavement material layer. The inventors of the present invention have found that when using conventional asphalt modifiers containing polyester resin, the hydrophilic polyester resin has low affinity with the coating film of pavement paints, which are mainly made of hydrophobic resins. This makes it easy for water to penetrate the interface between the asphalt pavement and the coating film of the pavement paint, resulting in the coating film being destroyed in a short period of time after its formation. In contrast, the polyester resin contained in the asphalt modifier of the present invention has highly hydrophobic and bulky rosin-derived organic acid-derived structural units, which give it highly hydrophobic regions. Therefore, it is believed that the affinity between the polyester resin and the hydrophobic coating film of the paving paint is improved, and the durability of the coating film of the paving paint applied on a paving material layer formed using an asphalt mixture containing the asphalt modifier of the present invention can be improved.

[0011] The definitions of various terms used in this specification are shown below. In polyester resins, "constituent units derived from alcohol components" refers to the structure obtained by removing a hydrogen atom from the hydroxyl group of an alcohol component, and "constituent units derived from carboxylic acid components" refers to the structure obtained by removing a hydroxyl group from the carboxyl group of a carboxylic acid component. The term "carboxylic acid component" is a concept that includes not only the carboxylic acid itself, but also anhydrides that decompose during the reaction to form an acid, and alkyl esters of carboxylic acids (for example, the number of carbon atoms in the alkyl group is 1 or more and 3 or less). However, polyethylene terephthalate is not included in the carboxylic acid component. When the carboxylic acid component is an alkyl ester of a carboxylic acid, the number of carbon atoms in the carboxylic acid does not include the number of carbon atoms in the alkyl group, which is the alcohol residue of the ester. Whether the resin is crystalline or amorphous is determined by the crystallinity index. The crystallinity index is defined as the ratio of the softening point of the resin to the temperature of the maximum peak of the endotherm (softening point (°C) / maximum peak temperature of the endotherm (°C)). A crystalline resin is one with a crystallinity index of 0.3 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, the crystallinity index is less than 0.3 or more than 1.4. The crystallinity index can be appropriately adjusted according to the type and ratio of the raw material monomers, as well as manufacturing conditions such as reaction temperature, reaction time, and cooling rate.

[0012] <Polyester resin> The polyester resin contained in the asphalt composition of the present invention is a polycondensate of an alcohol component and a carboxylic acid component, including a structural unit derived from the alcohol component and a structural unit derived from the carboxylic acid component. Examples of the polyester resin include amorphous polyester resins and crystalline polyester resins, and preferably amorphous polyester resins. Hereinafter, the physical properties of the alcohol component, carboxylic acid component, and polyester resin will be described.

[0013] (Alcohol component) Examples of the alcohol component include aliphatic diols, alicyclic diols, aromatic diols, polyhydric alcohols with three or more valences, etc. These alcohol components can be used alone or in combination of two or more.

[0014] As for the aliphatic diol, from the viewpoint of obtaining an asphalt modifier for obtaining an asphalt mixture that forms a pavement surface with excellent durability of the coating film of pavement paint (hereinafter referred to as "the viewpoint of obtaining excellent durability of the coating film of pavement paint"), it is preferably a linear or branched aliphatic diol having 2 to 6 carbon atoms, more preferably a linear or branched aliphatic diol having 2 to 4 carbon atoms, and even more preferably a branched aliphatic diol having 2 to 4 carbon atoms. Furthermore, from the viewpoint of availability and cost-effectiveness, the aliphatic diol is preferably a saturated aliphatic diol. Specific examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol. As for the aliphatic diol, from the viewpoint of obtaining excellent durability of the paving coating film, availability, and economy, one or more selected from ethylene glycol and 1,2-propanediol are preferred, and 1,2-propanediol is even more preferred from the viewpoint of obtaining excellent durability of the paving coating film.

[0015] Examples of alicyclic diols include hydrogenated bisphenol A (2,2-bis(4-hydroxycyclohexyl)propane), alkylene oxide adducts of hydrogenated bisphenol A, cyclohexanediol, and cyclohexanedimethanol.

[0016] 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 those represented by the following formula (I).

[0017] [ka]

[0018] In equation (I), OR 1 and R 1 O is an alkylene oxide, and R 1 x is an alkylene group having 2 or 3 carbon atoms, x and y are positive numbers representing 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 preferably 16 or less, more preferably 8 or less, and even more preferably 4 or less, from the viewpoint of productivity and availability of the alkylene oxide adduct of bisphenol A.

[0019] Examples of alkylene oxide adducts of bisphenol A represented by formula (I) include propylene oxide adducts of bisphenol A and ethylene oxide adducts of bisphenol A. These alkylene oxide adducts of bisphenol A can be used individually or in combination of two or more.

[0020] From the viewpoint of easily controlling the glass transition temperature and softening temperature of the polyester resin, trivalent or higher polyhydric alcohols are preferred. From the viewpoint of availability and economic efficiency, the number of carbon atoms in trivalent or higher polyhydric alcohols is 3 to 6. Examples of trivalent or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0021] The alcohol component may further contain monohydric aliphatic alcohols from the viewpoint of adjusting physical properties. Examples of monohydric aliphatic alcohols include lauryl alcohol, myristyl alcohol, palmityl alcohol, and stearyl alcohol. These monohydric aliphatic alcohols can be used individually or in combination of two or more.

[0022] (Carboxylic acid component) The carboxylic acid component includes an organic acid having a structure derived from rosin acid, from the viewpoint of obtaining excellent durability of the paving paint coating film.

[0023] Organic acids having a structure derived from rosin acid are compounds containing a carboxyl group found in natural resin rosin, unrefined rosin, refined rosin, and modified rosin. Specifically, these include abietic acid, neoabietic acid, palastic acid, pimaric acid, isopimaric acid, sandaracopimaric acid, dehydroabietic acid, and lepopimaric acid. Alternatively, organic acids obtained by adding one or more of these to one or more selected from acrylic acid, methacrylic acid, fumaric acid, and maleic acid are also included. An example of an addition reaction is the Diels-Alder reaction. Among these, abietic acid is preferred among organic acids having a structure derived from rosinic acid, from the viewpoint of obtaining excellent durability of the coating film for paving.

[0024] From the viewpoint of obtaining excellent durability of the paving paint coating film, the carboxylic acid component preferably further contains an aromatic dicarboxylic acid. Examples of aromatic dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, or their anhydrides, or their alkyl esters (for example, alkyl groups with 1 to 3 carbon atoms). Among these aromatic dicarboxylic acids, isophthalic acid and terephthalic acid are preferred, and terephthalic acid is more preferred, from the viewpoint of forming an asphalt pavement surface with excellent durability.

[0025] Furthermore, the carboxylic acid component may include aliphatic dicarboxylic acids and / or polycarboxylic acids with a valency of 3 to 6.

[0026] Examples of aliphatic dicarboxylic acids include those having four or more carbon atoms, preferably 10 or fewer, more preferably 8 or fewer, and more preferably 6 or fewer carbon atoms, such as fumaric acid, maleic acid, oxalic acid, malonic acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic 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 their anhydrides, or their alkyl esters (for example, alkyl groups with 1 to 3 carbon atoms). Examples of substituted succinic acids include dodecyl succinic acid, dodecenyl succinic acid, and octenyl succinic acid.

[0027] From the viewpoint of easily controlling the glass transition temperature and softening temperature of the polyester resin, trivalent to hexavalent polycarboxylic acids are preferred. Examples of trivalent to hexavalent polycarboxylic acids include trimellitic acid, 2,5,7-naphthalentricarboxylic acid, pyromellitic acid, or their acid anhydrides.

[0028] From the viewpoint of adjusting physical properties, the carboxylic acid component may further contain monovalent aliphatic carboxylic acids. Examples of monovalent aliphatic carboxylic acids include lauric acid, myristic acid, palmitic acid, stearic acid, and monovalent aliphatic carboxylic acids with 12 to 20 carbon atoms, such as alkyl (1 to 3 carbon atoms) esters of these acids. These monovalent aliphatic carboxylic acids can be used alone or in combination of two or more.

[0029] (Constituent units derived from polyethylene terephthalate) From the viewpoint of obtaining excellent durability of the paving coating film, the polyester resin may contain constituent units derived from polyethylene terephthalate, ethylene glycol, and terephthalic acid. In addition to the constituent units derived from ethylene glycol and terephthalic acid, polyethylene terephthalate may also contain small amounts of other components such as butanediol and isophthalic acid. From the viewpoint of SDGs, recycled polyethylene terephthalate is preferable. When a polyester resin contains constituent units consisting of ethylene glycol and terephthalic acid derived from polyethylene terephthalate, the "constituent units derived from alcohol components" include constituent units derived from ethylene glycol derived from polyethylene terephthalate, and the "constituent units derived from carboxylic acid components" include constituent units derived from terephthalic acid derived from polyethylene terephthalate.

[0030] (Preferred embodiment of polyester resin) In a preferred embodiment of the polyester resin, from the viewpoint of obtaining excellent durability of the paving coating film, the content of organic acid-derived structural units having a rosin-derived structure in the carboxylic acid-derived structural units is preferably 1 mol% or more, more preferably 4 mol% or more, even more preferably 6 mol% or more, even more preferably 12 mol% or more, even more preferably 18 mol% or more, and preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 35 mol% or less, even more preferably 32 mol% or less, and even more preferably 26 mol% or less. In a preferred embodiment of the polyester resin, from the viewpoint of obtaining excellent durability of the paving paint film, the content of constituent units derived from aromatic dicarboxylic acid components in constituent units derived from carboxylic acid components is preferably 30 mol% or more, more preferably 40 mol% or more, even more preferably 50 mol% or more, even more preferably 56 mol% or more, even more preferably 60 mol% or more, even more preferably 64 mol% or more, and preferably 95 mol% or less, more preferably 90 mol% or less, even more preferably 88 mol% or less, even more preferably 84 mol% or less, even more preferably 78 mol% or less, and even more preferably 72 mol% or less. Furthermore, in a preferred embodiment of the polyester resin, from the viewpoint of obtaining excellent durability of the paving paint coating film, the content of structural units derived from linear or branched aliphatic diol components having 2 to 4 carbon atoms in the structural units derived from the alcohol component is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, even more preferably 90 mol% or more, even more preferably 95 mol% or more, even more preferably 99 mol% or more, and even more preferably 100 mol%. Furthermore, in a preferred embodiment of the polyester resin, from the viewpoint of obtaining excellent durability of the paving paint coating film, the content of constituent units derived from the 1,2-propanediol component is preferably 30 mol% or more, more preferably 50 mol% or more, even more preferably 70 mol% or more, even more preferably 90 mol% or more, and even more preferably 100 mol% in 100 mol% of constituent units derived from the alcohol component. Furthermore, in a preferred embodiment of the polyester resin, from the viewpoint of obtaining excellent durability of the paving paint coating film, the content of constituent units derived from the ethylene glycol component is preferably 50 mol% or less, more preferably 40 mol% or less, even more preferably 30 mol% or less, even more preferably 10 mol% or less, even more preferably 5 mol% or less, and even more preferably 0 mol% in 100 mol% of constituent units derived from the alcohol component. Furthermore, in a preferred embodiment of the polyester resin, from the viewpoint of obtaining excellent durability of the paving paint coating film, the content of constituent units derived from the aromatic diol component is preferably 80 mol% or less, more preferably 60 mol% or less, even more preferably 30 mol% or less, even more preferably 10 mol% or less, even more preferably 5 mol% or less, and even more preferably 0 mol% in 100 mol% of constituent units derived from the alcohol component.

[0031] (Method of manufacturing polyester resin) The method for producing the polyester resin contained in the asphalt modifier of the present invention is not particularly limited, but for example, it can be produced by polycondensation of the alcohol component and carboxylic acid component described above. Details regarding the conditions for polycondensation between the alcohol component and the carboxylic acid component are described below in the [Method for Manufacturing Asphalt Modifier].

[0032] (Physical properties of polyester resin) The softening point of the polyester resin is preferably 80°C or higher, more preferably 90°C or higher, and more preferably 140°C or lower, more preferably 130°C or lower, and even more preferably 120°C or lower, from the viewpoint of forming an asphalt pavement surface with excellent durability. From a similar viewpoint, the glass transition temperature of the polyester resin is preferably 40°C or higher, more preferably 45°C or higher, even more preferably 48°C or higher, and preferably 80°C or lower, more preferably 75°C or lower, and even more preferably 70°C or lower. From the viewpoint of productivity of the polyester resin, the acid value of the polyester resin is preferably 1 mg KOH / g or more, more preferably 5 mg KOH / g or more, and even more preferably 10 mg KOH / g or more. From the viewpoint of forming an asphalt pavement surface with excellent durability, the acid value is preferably 30 mg KOH / g or less, more preferably 25 mg KOH / g or less, and even more preferably 20 mg KOH / g or less. The hydroxyl value of the polyester resin is preferably 0.5 mg KOH / g or more, more preferably 1 mg KOH / g or more, and even more preferably 3 mg KOH / g or more, from the viewpoint of the productivity of the polyester resin, and preferably 15 mg KOH / g or less, more preferably 10 mg KOH / g or less, and even more preferably 8 mg KOH / g or less, from the viewpoint of forming an asphalt pavement surface with excellent durability.

[0033] The softening point, glass transition temperature, acid value, and hydroxyl value of the polyester resin can be measured by the method described in the examples. Note that the softening point, glass transition temperature, acid value, and hydroxyl value can be adjusted by the raw material monomer composition, molecular weight, catalyst amount, or reaction conditions.

[0034] The asphalt modifier of the present invention may contain a polyester resin that has been modified to such an extent that its properties are not substantially impaired. Specifically, the modified polyester resin may be a polyester resin that has been grafted or blocked with phenol, urethane, epoxy, etc., by methods described in Japanese Patent Publication No. 11-133668, Japanese Patent Publication No. 10-239903, Japanese Patent Publication No. 8-20636, etc. A preferred modified polyester resin is a urethane-modified polyester resin obtained by urethane elongation of a polyester resin with a polyisocyanate compound.

[0035] (Polyester resin content) From the viewpoint of forming an asphalt pavement surface with excellent durability, the polyester resin content in the asphalt modifier is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more, and even more preferably 100% by mass.

[0036] The asphalt modifier is preferably in powder form. More specifically, the asphalt modifier is in powder form, and from the viewpoint of ease of handling, the average particle size is preferably less than 5 mm, more preferably 3 mm or less, even more preferably 1 mm or less, and preferably 10 μm or more, more preferably 50 μm or more, and even more preferably 100 μm or more. The average particle size of the asphalt modifier powder can be measured by sieving. Here, the average particle size refers to the average particle size at 50% weight cumulative.

[0037] The asphalt modifier of the present invention can be used, for example, by mixing it with asphalt to obtain an asphalt composition. The modifier of the present invention modifies the asphalt so that a pavement surface with excellent durability is formed. The obtained asphalt composition can be used for paving after adding heated aggregate to form an asphalt mixture. The asphalt modifier of the present invention can be suitably used as an asphalt modifier for modified asphalt to be blended into an asphalt mixture containing aggregate.

[0038] [Manufacturing method for asphalt modifiers] The present invention provides a method for producing an asphalt modifier, comprising the step of polycondensing a monomer mixture containing an alcohol component and a carboxylic acid component. Here, the carboxylic acid component includes an organic acid having a rosin-derived structure.

[0039] As for the alcohol component, the alcohol components listed above in the section on <polyester resin> can be used, and the same applies to preferred alcohol components.

[0040] As the carboxylic acid component, the carboxylic acid components listed above in <Polyester Resin> can be used, and the same applies to preferred carboxylic acids.

[0041] The content of organic acids and aromatic dicarboxylic acid components having a rosin-derived structure in the carboxylic acid component, and the content of linear or branched aliphatic diols having 2 to 4 carbon atoms in the alcohol component, the content of 1,2-propanediol, the content of ethylene glycol, and the content of aromatic diols are the same as, respectively, the content of organic acid-derived components having a rosin-derived structure and aromatic dicarboxylic acid-derived components in the carboxylic acid component-derived component, and the content of linear or branched aliphatic diol components having 2 to 4 carbon atoms, the content of 1,2-propanediol-derived components, and the content of aromatic diol-derived components in the alcohol component-derived component, as described above (preferred embodiment of polyester resin).

[0042] The monomer mixture may be a raw material mixture containing polyethylene terephthalate, from the viewpoint of obtaining excellent durability of the paving paint coating. In addition to constituent units derived from ethylene glycol and terephthalic acid, the polyethylene terephthalate may also contain small amounts of components such as constituent units derived from butanediol and isophthalic acid. From the viewpoint of SDGs, recycled polyethylene terephthalate is preferable. If the raw material mixture contains polyethylene terephthalate, the "alcohol component" contains ethylene glycol derived from polyethylene terephthalate, and the "carboxylic acid component" contains terephthalic acid derived from polyethylene terephthalate.

[0043] (A process of polycondensing a monomer mixture containing alcohol and carboxylic acid components.) In the step of polycondensing a monomer mixture containing an alcohol component and a carboxylic acid component, the temperature of the polycondensation reaction is not particularly limited, but from the viewpoint of adjusting the reactivity and productivity, it is preferably 160°C to 260°C.

[0044] From the viewpoint of reaction rate, an esterification catalyst can be used in the polycondensation reaction. Examples of esterification catalysts include tin(II) compounds that do not have a Sn-C bond, such as di(2-ethylhexanoic acid)tin(II). From the viewpoint of reaction rate, the amount of esterification catalyst used is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, even more preferably 0.2 parts by mass or more, and preferably 1.5 parts by mass or less, more preferably 1.0 part by mass or less, and even more preferably 0.8 parts by mass or less, per 100 parts by mass of the total amount of polyethylene terephthalate, alcohol component, and carboxylic acid component. In addition to the esterification catalyst, a co-catalyst can be used in the polycondensation reaction. Examples of co-catalysts include pyrogallol compounds such as gallic acid. The amount of co-catalyst used is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.01 parts by mass or more, and preferably 0.20 parts by mass or less, more preferably 0.15 parts by mass or less, and even more preferably 0.10 parts by mass or less, based on 100 parts by mass of the total amount of the alcohol component and the carboxylic acid component.

[0045] [Asphalt mixture] The asphalt mixture of the present invention comprises asphalt, aggregate, and the above-mentioned asphalt modifier.

[0046] <Asphalt> The asphalt mixture of the present invention may include straight asphalt and / or modified asphalt as the asphalt. Examples of modified asphalt include blown asphalt, which is obtained by heating a mixture of straight asphalt and heavy oil and then blowing air into it to oxidize it; and polymer-modified asphalt, which is obtained by modifying asphalt with a polymer material such as a thermoplastic elastomer or thermoplastic resin.

[0047] Examples of thermoplastic elastomers used in polymer-modified asphalt modified with thermoplastic elastomers include at least one selected from styrene / butadiene block copolymer, styrene / butadiene / styrene block copolymer, styrene / butadiene random copolymer, styrene / isoprene block copolymer, styrene / isoprene / styrene block copolymer, styrene / isoprene random copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid ester copolymer, styrene / ethylene / butylene / styrene copolymer, styrene / ethylene / propylene / styrene copolymer, polyurethane-based thermoplastic elastomer, polyolefin-based thermoplastic elastomer, isobutylene / isoprene copolymer, polyisoprene, polychloroprene, synthetic rubber other than those listed above, and natural rubber. The thermoplastic elastomer in the modified asphalt is preferably at least one selected from styrene / butadiene block copolymer, styrene / butadiene / styrene block copolymer, styrene / butadiene random copolymer, styrene / isoprene block copolymer, styrene / isoprene / styrene block copolymer, styrene / isoprene random copolymer, ethylene / vinyl acetate copolymer, and ethylene / acrylic acid ester copolymer. Among these, the thermoplastic elastomer is preferably at least one selected from styrene / butadiene block copolymer, styrene / butadiene / styrene block copolymer, styrene / butadiene random copolymer, styrene / isoprene block copolymer, styrene / isoprene / styrene block copolymer, styrene / isoprene random copolymer, and ethylene / acrylic acid ester copolymer, more preferably at least one selected from styrene / butadiene block copolymer, styrene / butadiene / styrene block copolymer, styrene / butadiene random copolymer, styrene / isoprene block copolymer, and styrene / isoprene random copolymer, and even more preferably at least one selected from styrene / butadiene random copolymer and styrene / butadiene / styrene block copolymer. From the viewpoint of forming an asphalt pavement surface with excellent durability, the content of thermoplastic elastomer in polymer-modified asphalt is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, even more preferably 1% by mass or more, and preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0048] <Aggregates> As aggregate, crushed stone, boulders, gravel, sand, recycled aggregate, ceramics, etc., can be arbitrarily selected and used. In addition, both coarse aggregate with a particle size of 2.36 mm or larger and fine aggregate with a particle size of less than 2.36 mm can be used. Recycled aggregate is made by collecting used asphalt pavement, crushing it, and classifying it. Examples of coarse aggregate include crushed stone with a particle size range of 2.36 mm or more and less than 4.75 mm, crushed stone with a particle size range of 4.75 mm or more and less than 12.5 mm, crushed stone with a particle size range of 12.5 mm or more and less than 19 mm, and crushed stone with a particle size range of 19 mm or more and less than 31.5 mm. The fine aggregate is preferably fine aggregate with a particle size of 0.075 mm or more and less than 2.36 mm. Examples of fine aggregate include river sand, hill sand, mountain sand, sea sand, crushed sand, fine sand, screenings, crushed stone dust, silica sand, artificial sand, glass cullet, foundry sand, and recycled aggregate crushed sand. The particle size values ​​mentioned above are those specified in JIS A5001:2008. Among these, a combination of coarse aggregate and fine aggregate is preferred.

[0049] Furthermore, the fine aggregate may contain fillers with a particle size of less than 0.075 mm. Examples of fillers include sand, fly ash, calcium carbonate such as limestone powder, and slaked lime. Of these, calcium carbonate is preferred from the viewpoint of forming an asphalt pavement surface with excellent strength. The average particle size of the filler is preferably 0.001 mm or larger, more preferably 0.06 mm or smaller, more preferably 0.04 mm or smaller, and even more preferably 0.03 mm or smaller, from the viewpoint of forming an asphalt pavement surface with excellent dry strength. The average particle size of the filler can be measured with a laser diffraction particle size distribution analyzer. Here, the average particle size refers to the average particle size of 50% of the volume cumulative.

[0050] From the viewpoint of forming an asphalt pavement surface with excellent durability, the mass ratio of coarse aggregate to fine aggregate is preferably 10 / 90 or more, more preferably 20 / 80 or more, even more preferably 30 / 70 or more, and preferably 90 / 10 or less, more preferably 80 / 20 or less, and even more preferably 70 / 30 or less.

[0051] The following (1) to (3) are examples of suitable formulations for asphalt mixtures. (1) For example, fine-grained asphalt comprising coarse aggregate of 30% to less than 45% by volume, fine aggregate of 30% to 50% by volume, and an asphalt composition of 5% to 10% by volume. (2) For example, dense-graded asphalt comprising coarse aggregate of 45% to less than 70% by volume, fine aggregate of 20% to 45% by volume, and asphalt composition of 3% to 10% by volume. (3) For example, porous asphalt comprising 70% to 80% by volume of coarse aggregate, 10% to 20% by volume of fine aggregate, and 3% to 10% by volume of asphalt composition.

[0052] The above porous asphalt can be suitably used for permeable pavement.

[0053] From the viewpoint of forming an asphalt pavement surface with excellent durability, the aggregate content in the asphalt mixture is preferably 50% by mass or more, more preferably 75% by mass or more, even more preferably 80% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 96% by mass or less.

[0054] In addition, the mixing ratio of asphalt in conventional asphalt mixtures containing aggregate and asphalt is usually determined according to the optimal amount of asphalt found in the "Asphalt Composition Mix Design" described in the "Pavement Design and Construction Guidelines" published by the Japan Road Association. In this invention, the above-mentioned optimal amount of asphalt corresponds to the total amount of asphalt and asphalt modifier. However, it is not necessary to limit the method to the method described in the "Guidelines for Pavement Design and Construction," and it may be determined by other methods.

[0055] From the viewpoint of forming an asphalt pavement surface with excellent durability, the asphalt content in the asphalt mixture is preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 4% by mass or more, and preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less.

[0056] The content of the asphalt modifier in the asphalt mixture of the present invention is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, per 100 parts by mass of asphalt, from the viewpoint of obtaining excellent durability of the paving coating film, and preferably 35 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 25 parts by mass or less, from the viewpoint of workability.

[0057] The asphalt mixture may also contain other components as needed.

[0058] <Method for producing asphalt mixture> The asphalt mixture of the present invention can be obtained by blending asphalt, heated aggregate, and an asphalt modifier. The method for producing the asphalt mixture of the present invention includes the step of mixing asphalt, heated aggregate, and asphalt modifier simultaneously or in any order. Specific methods for manufacturing asphalt mixtures include conventional methods such as the plant mix method and the premix method. Both methods involve adding asphalt and polyester resin to heated aggregate. The above mixing step is preferably one of the following (i) to (iii). (i) After adding and mixing asphalt to heated aggregate, add and mix asphalt modifier. (ii) Adding and mixing asphalt and asphalt modifier to heated aggregate simultaneously, (iii) Add and mix the preheated aggregate with the mixture of asphalt and asphalt modifier.

[0059] The temperature of the heated aggregate in methods (i) to (iii) is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, from the viewpoint of forming an asphalt pavement surface with excellent durability, and 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.

[0060] From the viewpoint of forming an asphalt pavement surface with excellent durability, the mixing temperature of the aggregate and asphalt and / or polyester resin is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher. From the viewpoint of preventing thermal degradation of the asphalt, the mixing temperature is preferably 230°C or lower, more preferably 210°C or lower, and even more preferably 200°C or lower. The mixing time between the aggregate and asphalt is not particularly limited, but is preferably 30 seconds or more, more preferably 1 minute or more, and even more preferably 2 minutes or more. The upper limit of the time is not particularly limited, but is preferably about 30 minutes. From the viewpoint of manufacturing efficiency, the mixing time between the aggregate and asphalt mixture and the asphalt modifier is preferably 20 seconds or more, more preferably 30 seconds or more, even more preferably 40 seconds or more, preferably 1 minute 30 seconds or less, more preferably 1 minute 20 seconds or less, and even more preferably 1 minute 10 seconds or less. The mixing time refers to the time from when the entire amount of asphalt modifier is added until the mixing is completed. From the viewpoint of manufacturing efficiency, the time required to add the entire amount of asphalt modifier is preferably 1 minute or less from the start to the end of the addition, more preferably 45 seconds or less, and even more preferably 30 seconds or less.

[0061] From the viewpoint of forming an asphalt pavement surface with excellent durability, the method for producing the asphalt mixture preferably includes a step of holding the obtained mixture at the above-mentioned mixing temperature after the mixing step. In the process of holding the asphalt mixture, the mixture may be further mixed. The holding time is preferably 0.2 hours or more, more preferably 0.3 hours or more, and even more preferably 0.5 hours or more. The upper limit of the time is not particularly limited, but is preferably 5 hours or less, more preferably 4 hours or less, and even more preferably 3 hours or less.

[0062] [Paving Method] The asphalt mixture of the present invention is suitable for paving, and suitable applications for paving include roads, parking lots, and the like. The paving method includes the step of applying the aforementioned asphalt mixture to the area to be paved to form an asphalt paving material layer. The asphalt paving material layer is usually a base layer or a surface layer, and from the viewpoint of obtaining an asphalt pavement with excellent durability, it is preferably a surface layer.

[0063] The thickness of the asphalt pavement layer is preferably 3 cm or more, more preferably 4 cm or more, even more preferably 4.5 cm or more, and preferably 7 cm or less, more preferably 6 cm or less, and even more preferably 5.5 cm or less, from the viewpoint of forming an asphalt pavement surface with excellent durability. In another embodiment of the present invention, the asphalt pavement layer can be a thin-layer pavement, and the thickness of the surface layer is preferably 1 cm or more, more preferably 1.5 cm or more, even more preferably 2 cm or more, and preferably 4 cm or less, more preferably 3.5 cm or less, and even more preferably 3 cm or less. The asphalt mixture can be compacted using a known construction machinery setup and a similar method. When used as a heated asphalt mixture, the compaction temperature is preferably 100°C or higher, more preferably 120°C or higher, even more preferably 130°C or higher, and preferably 200°C or lower, more preferably 180°C or lower, from the viewpoint of forming an asphalt pavement surface with excellent durability.

[0064] The above paving method may further include a step of applying paint to the asphalt paving material layer formed above. The paints used for painting are not particularly limited, but examples include powder coatings containing a colorant and a thermoplastic resin such as petroleum resin or rosin resin, and water-based paints in which a colorant and an acrylic resin, alkyd resin, etc. are dispersed in an aqueous solvent.

[0065] The colorants used in the paint may include either organic or inorganic pigments, such as white pigments like titanium dioxide and zinc oxide. Extender pigments such as calcium carbonate, silica powder, and granite, as well as glass beads, can also be used.

[0066] When applying a coating to an asphalt pavement layer using powder coating, for example, the powder coating can be melted by heating it to about 200°C, and then applied to the surface of the asphalt pavement layer using an application machine and cooled to complete the coating. Furthermore, when applying paint to an asphalt pavement layer using water-based paint, the paint can be applied by, for example, using a brush or roller to apply and dry the water-based paint on the surface of the asphalt pavement layer. [Examples]

[0067] Various physical properties were measured and evaluated using the following methods. In the following examples and comparative examples, unless otherwise specified, parts and percentages are based on mass.

[0068] (1) Softening point of polyester resin Using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation), 1 g of sample was heated at a heating rate of 6°C / min while a load of 1.96 MPa was applied by a plunger and extruded from a nozzle with a diameter of 1 mm and a length of 1 mm. The amount of plunger descent of the flow tester was plotted against temperature, and the temperature at which half of the sample flowed out was defined as the softening point.

[0069] (2) Glass transition temperature (Tg) of polyester resin Using a differential scanning calorimeter "Q-100" (manufactured by T.A. Instruments Japan Co., Ltd.), 0.01 to 0.02 g of the sample was weighed into an aluminum pan, heated to 200°C, and then cooled to 0°C at a rate of 10°C / min. Subsequently, the heat content of the sample was measured while heating to 150°C at a rate of 10°C / min. The glass transition temperature was defined as the temperature at the intersection of the extension of the baseline below the maximum endothermic peak temperature and the tangent line representing the maximum slope from the peak's rising portion to its peak. Furthermore, if a step was observed without an endothermic peak, the temperature at the intersection of the tangent line showing the maximum slope of the curve in the step portion and the extension of the baseline on the lower temperature side of the step was defined as the glass transition temperature.

[0070] (3) Crystallinity index The crystallinity index is defined as the ratio of the softening point of a resin to the temperature of the maximum endothermic peak (softening point (°C) / maximum endothermic peak temperature (°C)). Crystalline resins are those with a crystallinity index of 0.3 or higher and 1.4 or lower. Amorphous resins are those in which no endothermic peak is observed, or, if observed, have a crystallinity index of less than 0.3 or greater than 1.4.

[0071] (4) 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)).

[0072] (5) Method for measuring the weight-average molecular weight of polyester resin The molecular weight distribution was measured using the following gel permeation chromatography (GPC) method, and the weight-average molecular weight was determined. (i) Preparation of sample solution The sample was dissolved in a solvent at 25°C to a concentration of 0.5 g / 100 mL. This solution was then filtered using a fluoropolymer filter with a pore size of 0.2 μm (DISMIC-25JP, manufactured by Toyo Roshi Co., Ltd.) to remove undissolved material and obtain the sample solution. Tetrahydrofuran was used as the solvent. (ii) Molecular weight measurement Using the measuring apparatus and analytical column described below, the same solvent used to prepare the sample solution was flowed at a flow rate of 1 mL per minute as the eluent, and the column was stabilized in a constant temperature bath at 40°C. 100 μL of the sample solution was injected into the column and measurements were performed. The molecular weight of the sample was calculated based on a calibration curve prepared in advance. The calibration curve used in this measurement included several types of monodisperse polystyrene "A-500" (5.0 × 10⁻¹⁰). 2 ), "A-1000" (1.01 x 10 3 ), "A-2500" (2.63 x 10 3 ), "A-5000" (5.97 x 10 3)、 "F-1" (1.02×10 3 )、 "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 )(Above, manufactured by Tosoh Corporation) were used as standard samples. Measuring device: "HLC-8220CPC" (manufactured by Tosoh Corporation) Analysis column: "GMHXL" + "G3000HXL" (manufactured by Tosoh Corporation)

[0073] <Manufacture of Asphalt Modifier> Example 1-1 (Manufacture of Polyester Resin A1 as Asphalt Modifier) Among the raw material mixtures shown in Table 1, 1,2-propanediol, terephthalic acid, and white chrysanthemum rosin (manufactured by Arakawa Chemical Industries, Ltd., molecular weight 336), di(2-ethylhexanoic acid)tin(II) (manufactured by Nitto Kasei Co., Ltd., trade name "Neostan E-80") and gallic acid were placed in a 5-liter four-necked flask equipped with a thermometer, a stainless steel stirring rod, a fractionating tube through which hot water at 100°C passed, a water removal tube, and a nitrogen introduction tube. In a nitrogen atmosphere, the reaction system was heated to 180°C while stirring in a mantle heater, held at 180°C for 1 hour, then heated from 180°C to 230°C at 5°C / h, and then held at 230°C for 5 hours to carry out a polycondensation reaction. After cooling the reaction system to 180°C, succinic acid was added to the reaction system, and the reaction system was heated to 210°C over 2 hours. Then, it was held at 210°C for 1 hour, and the reaction was further carried out under a reduced pressure of 8.0 kPa until the softening point reached the temperature shown in Table 1, to obtain polyester resin A1 as an asphalt modifier. The physical properties of polyester resin A1 are shown in Table 1. When the glass transition temperature of polyester resin A1 was measured using the method described above, a step was observed without an endothermic peak, as shown in Figure 1. Therefore, the temperature at the intersection of the maximum slope tangent of the curve at the step and the extension of the baseline on the lower temperature side of the step, 56.4°C, was defined as the glass transition temperature. The weight-average molecular weight of polyester resin A1 was 2640.

[0074] Examples 1-2 to 1-9 and Comparative Manufacturing Example 1 (Manufacturing of polyester resins A2 to A9 and A12 as asphalt modifiers) Polyester resins A2-A9 and A12 were obtained as asphalt modifiers in the same manner as in Example 1-1, except that the raw material mixture was changed as shown in Table 1. The physical properties of polyester resins A2-A9 and A12 are shown in Table 1.

[0075] Examples 1-10 (Production of polyester resin A10 as an asphalt modifier) From the raw material mixture shown in Table 1, BPA-EO, terephthalic acid, Shiragiku rosin (manufactured by Arakawa Chemical Industries, Ltd., molecular weight 336), and polyethylene terephthalate, along with di(2-ethylhexanoate tin(II) (manufactured by Nitto Kasei Co., Ltd., trade name "Neostan E-80")) and gallic acid, were placed in a 5-liter four-necked flask equipped with a thermometer, stainless steel stirring rod, fall-flow condenser, and nitrogen inlet tube. The reaction system was heated to 235°C in a mantle heater under a nitrogen atmosphere while stirring. The condensation polymerization reaction was carried out by holding the system at 235°C for 8 hours. After cooling the reaction system to 180°C, succinic acid was added to the reaction system, and the system was heated to 210°C over 2 hours. Then, it was held at 210°C for 1 hour, and the reaction was further carried out under reduced pressure of 8.0 kPa until the softening point reached the temperature shown in Table 1, yielding polyester resin A10 as an asphalt modifier. The physical properties of polyester resin A10 are shown in Table 1.

[0076] Example 1-11 (Production of polyester resin A11 as an asphalt modifier) Polyester resin A11 was obtained as an asphalt modifier in the same manner as in Examples 1-10, except that the raw material mixture was changed as shown in Table 1. The physical properties of polyester resin A11 are shown in Table 1.

[0077] [Table 1]

[0078] <Manufacturing of asphalt mixtures and evaluation of coating films> Example 2-1 (Production of Asphalt Mixture AS-1) 100g of straight asphalt 60-80 (manufactured by Mitsubishi Corporation Energy Co., Ltd.), heated to 180°C in a constant temperature bath, was placed in a 200mL SUS beaker set up on a hot plate. While stirring at 200rpm with a disc turbine type stirring blade, 10g of polyester resin A1 produced in Example 1-1 as an asphalt modifier was added, and the mixture was mixed at 180°C for 30 minutes to obtain asphalt mixture AS-1.

[0079] (Evaluation of the durability of the coating film of paving paint) The obtained asphalt mixture AS-1 was quickly and evenly applied to the entire surface of a test piece (slate board: 150 mm long, 70 mm wide, 4.0 mm thick) manufactured by AS ONE Corporation at 180°C using an applicator (film thickness 50 μm). The mixture was then left to stand until it reached room temperature (25°C) to create a layer of asphalt mixture. The surface was then masked with mending tape to create a 2 cm x 2 cm square area. Water-based paint (Asahi Paint Co., Ltd.'s "Water-based Road Marking Paint") was roughly applied to the surface of the asphalt mixture layer using a brush, smoothed with a stainless steel rod, and then dried at 40°C for 6 hours. After drying, the mending tape was removed, and an asphalt coating film was produced on the surface of the asphalt mixture layer. This evaluation was a simple assessment of the durability of the paving coating film on the surface layer of the asphalt mixture, and therefore the asphalt mixture was not made to contain aggregate. The manufactured asphalt coating was immersed in 60°C hot water for 6 hours, then left to stand at room temperature for 2 hours. After removing surface water droplets by lightly wiping with Kimwipes (registered trademark) (manufactured by Nippon Paper Crecia Co., Ltd.), it was left to stand in a freezer set to -10°C for 6 hours. The asphalt coating was removed from the freezer and left to stand in the air at room temperature for 2 hours. This cycle was repeated until the coating peeled off, and the number of cycles at which the coating peeled off was defined as the durability of the paving coating. The results are shown in Table 2.

[0080] Examples 2-1 to 2-13 and Comparative Example 1 An asphalt mixture was obtained in the same manner as in Example 1, except that the polyester resin A1 and its quantity were changed as shown in Table 2. An asphalt coating was applied using the obtained asphalt mixture, and the asphalt coating was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0081] Reference example An asphalt coating was manufactured using Straight Asphalt 60-80 (manufactured by Mitsubishi Corporation Energy Co., Ltd.), and the asphalt coating was evaluated in the same manner as in Example 1. However, during the initial hot water immersion, the asphalt coating peeled off from the slate board, making evaluation impossible.

[0082] [Table 2]

[0083] The results in Table 2 show that the asphalt coatings of Examples 2-1 to 2-13, which were formed on asphalt modified with an asphalt modifier containing a polyester resin that includes organic acid-derived structural units having a rosin-derived structure, exhibit superior durability compared to the asphalt coating of Comparative Example 1, which was formed on asphalt modified with an asphalt modifier containing a polyester resin that does not include organic acid-derived structural units having a rosin-derived structure.

Claims

1. An asphalt modifier containing a polyester resin that includes constituent units derived from alcohol components and constituent units derived from carboxylic acid components, An asphalt modifier in which the constituent units derived from the carboxylic acid component include constituent units derived from an organic acid having a rosin-derived structure.

2. The asphalt modifier according to claim 1, wherein the content of organic acid-derived structural units having a rosin-derived structure in the carboxylic acid-derived structural units is 1 mol% or more and 50 mol% or less.

3. The asphalt modifier according to claim 1, wherein the constituent units derived from the carboxylic acid component further include constituent units derived from an aromatic dicarboxylic acid.

4. The asphalt modifier according to claim 3, wherein the content of the aromatic dicarboxylic acid-derived structural unit in the structural unit derived from the carboxylic acid component is 30 mol% or more and 90 mol% or less.

5. The asphalt modifier according to claim 1, wherein the glass transition temperature of the polyester resin is 40°C or higher.

6. The asphalt modifier according to claim 1, wherein the constituent units derived from the alcohol component include constituent units derived from a linear or branched aliphatic diol having 2 to 4 carbon atoms.

7. The asphalt modifier according to claim 6, wherein the content of structural units derived from the alcohol component is 30 mol% or more of the structural units derived from the linear or branched aliphatic diol having 2 to 4 carbon atoms.

8. An asphalt mixture containing asphalt, aggregate, and an asphalt modifier according to any one of claims 1 to 7.

9. The asphalt mixture according to claim 8, wherein the mixture contains 1 to 30 parts by mass of the asphalt modifier per 100 parts by mass of the asphalt.

10. A paving method comprising the steps of applying the asphalt mixture described in claim 8 to a paving target and forming an asphalt paving material layer.

11. Furthermore, the paving method according to claim 10, further comprising the step of applying paint to the asphalt paving material layer.

12. A method for producing an asphalt modifier containing a polyester resin, comprising the step of polycondensing a monomer mixture containing an alcohol component and a carboxylic acid component, A method for producing an asphalt modifier, wherein the carboxylic acid component contains an organic acid having a rosin-derived structure.

13. The method for producing an asphalt modifier according to claim 12, wherein the content of an organic acid having a rosin-derived structure in the carboxylic acid component is 1 mol% or more and 50 mol% or less.

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