Additive for asphalt compositions

Abstract

The purpose of the present invention is to provide a lignin derivative compound which is capable of efficiently improving the physical properties of asphalt. Specifically, the present invention provides: an additive for asphalt compositions, which contains a lignin derivative compound that contains a constituent unit (I) which is derived from a lignin-based compound and a constituent unit (II) which is derived from an aromatic water-soluble compound that includes at least an aromatic water-soluble compound having an alkylene oxide chain; and an asphalt composition which contains the lignin derivative compound and asphalt.

Description

Additives for asphalt compositions

[0001] The present invention relates to an additive for an asphalt composition.

[0002] Asphalt is widely used for paving surfaces on roads and other ground surfaces. Development of various asphalt modifiers (modifiers) is underway to improve physical properties such as maintaining fluidity and reducing viscosity during high-temperature processing in asphalt paving. For example, Patent Document 1 describes that the viscosity of asphalt at high temperatures can be reduced by adding compounds such as bis(3-aminopropyl) disulfide and bis(2-aminoethyl) disulfide.

[0003] On the other hand, Patent Document 2 describes that a lignin derivative compound, which is a reaction product of a lignin sulfonic acid compound and a water-soluble aromatic compound, exhibits high dispersibility in cement, gypsum, and the like.

[0004] International Publication No. 2016 / 121580 Patent No. 7154217

[0005] The modifier in Patent Document 1 is added to molten asphalt or a mixture of asphalt and aggregate while stirring, and compatibility at low temperatures is not taken into consideration. Furthermore, Patent Document 2 improves the dispersibility of a substance to be dispersed in water as a dispersion medium, but does not describe improving dispersibility in a substance that does not substantially contain water, such as an asphalt composition.

[0006] An object of the present invention is to provide a lignin derivative compound that can efficiently improve the physical properties of asphalt.

[0007] The present invention provides the following items [1] to [7]. [1] An additive for asphalt compositions, comprising a lignin derivative compound containing the following structural units (I) and (II): (I): a structural unit derived from a lignin-based compound; (II): a structural unit derived from an aromatic water-soluble compound containing at least an aromatic water-soluble compound having an alkylene oxide chain; [2] The agent according to [1], wherein the aromatic water-soluble compound having an alkylene oxide chain comprises an aromatic water-soluble compound having an alkylene oxide chain with an average number of alkylene oxide addition moles of 25 or more. [3] The agent according to [1] or [2], comprising a lignin derivative compound in which the weight ratio (I) / (II) of structural unit (I) to structural unit (II) is 1 / 99 to 99 / 1. [4] An asphalt composition comprising a lignin derivative compound containing the following structural units (I) and (II) and asphalt. (I): A structural unit derived from a lignin-based compound (II): A structural unit derived from an aromatic water-soluble compound containing at least an aromatic water-soluble compound having an alkylene oxide chain. [5] The asphalt composition according to [4], wherein the content of the lignin derivative compound per 100 parts by weight of asphalt is 0.005 to 3.0 parts by weight. [6] The asphalt composition according to [4] or [5], further comprising aggregate, for use in road paving. [7] A pavement comprising the asphalt composition according to any one of [4] to [6].

[0008] According to the present invention, there is provided an asphalt composition that can suppress an increase in viscosity of the asphalt composition and exhibit good compatibility with asphalt at low temperatures.

[0009] FIG. 1 is an image of a GPC chart (UV detection wavelength: 280 nm) of a lignin derivative compound for explaining the peak area ratio of high molecular weight components.

[0010] [1. Additive for Asphalt Composition] The additive for asphalt composition contains the following lignin derivative compound as an active ingredient.

[0011] [1.1 Structural Units of Lignin Derivative Compounds] Lignin derivative compounds are polymers containing at least structural units (I) and (II). Because lignin, which is the main skeleton of structural unit (I), has a very complex molecular structure, it is difficult to uniformly specify the chemical structure of lignin derivative compounds by a general formula or the like.

[0012] —Structural Unit (I)—The structural unit (I) is a structural unit derived from a lignosulfonic acid compound. A lignosulfonic acid compound is a compound having a skeleton in which a sulfo group (sulfonic acid group) has been introduced by cleavage of the carbon at the α-position of the side chain of the hydroxyphenylpropane structure of lignin. The structure of the skeleton portion is shown in formula (1).

[0013] The lignosulfonic acid compound may be a modified product of a compound having the skeleton represented by formula (1) (hereinafter also referred to as a "modified lignosulfonic acid compound"). The modification method is not particularly limited, and examples include chemical modification methods such as hydrolysis, alkylation, alkoxylation, sulfonation, sulfonate esterification, sulfomethylation, aminomethylation, and desulfonation; and molecular weight fractionation of the lignosulfonic acid compound by ultrafiltration. Among these, the chemical modification method is preferably one or more modification methods selected from hydrolysis, alkoxylation, desulfonation, and alkylation.

[0014] The lignosulfonic acid compound may be in the form of a salt. Examples of the salt include monovalent metal salts, divalent metal salts, ammonium salts, and organic ammonium salts. Among these, calcium salts, magnesium salts, sodium salts, and calcium-sodium mixed salts are preferred.

[0015] Lignosulfonic acid compounds typically have at least one functional group moiety capable of reacting with the aromatic water-soluble compound that constitutes the structural unit (II). Examples of such moieties include a carboxyl group, a hydroxyl group (phenolic hydroxyl group, alcoholic hydroxyl group), a thiol group, a sulfo group, an aromatic ring, an ether bond, and an alkyl chain. In one embodiment, the functional group moiety of the lignosulfonic acid compound is bonded to the aromatic water-soluble compound directly or via a condensing agent such as formaldehyde to form a lignin derivative compound.

[0016] The method for producing the lignosulfonate-based compound and its origin are not particularly limited, and either natural or synthetic products may be used. Lignin sulfonate-based compounds are one of the main components of sulfite pulp waste liquor obtained by cooking wood under acidic conditions. Therefore, lignosulfonate-based compounds derived from sulfite pulp waste liquor may be used.

[0017] -Structural Unit (II)- The structural unit (II) is a structural unit derived from a water-soluble aromatic compound. An aromatic water-soluble compound refers to a compound that contains at least one aromatic skeleton and exhibits water solubility. The aromatic water-soluble compound is preferably a compound that can bond through a chemical reaction with a functional group contained in a lignosulfonic acid compound, and more preferably a compound that can react with a functional group contained in a lignosulfonic acid compound that is the main component of sulfite pulp waste liquor. The type of chemical reaction is not particularly limited, and examples include a radical reaction, an ionic bond, a coordinate bond, a condensation reaction, a reaction involving hydrolysis, a reaction involving dehydration, a reaction involving oxidation, a reaction involving reduction, and a reaction involving neutralization.

[0018] The aromatic water-soluble compound preferably has an alkylene oxide chain or a polar group. This can improve the reactivity when forming a bond between the structural units (I) and (II). The polar group may be an ionic functional group, such as a carboxyl group, a hydroxyl group, a sulfo group, a nitroxyl group, a carbonyl group, a phosphate group, an amino group, or an epoxy group. Anionic functional groups such as a hydroxyl group, a carboxyl group, a sulfo group, or a phosphate group are preferred, and a carboxyl group or a sulfo group is more preferred. The anionic functional group in the lignin derivative compound can be quantitatively and qualitatively observed by instrumental analysis such as NMR or IR.

[0019] Examples of the aromatic water-soluble compound include the following compounds.

[0020] (Aromatic Water-Soluble Compound Having an Alkylene Oxide Chain) The number of carbon atoms in the alkylene oxide units constituting the alkylene oxide chain (group) is not particularly limited, and is typically 2 to 18, preferably 2 to 4, and more preferably 2 to 3. Examples of alkylene oxide units include ethylene oxide units, propylene oxide units, and butylene oxide units, with ethylene oxide units or propylene oxide units being preferred. The average number of moles of alkylene oxide units added is typically 20 or more or 25 or more, preferably 30 or more, and more preferably 35 or more. This can further improve the stability of the asphalt composition. The upper limit is preferably 300 or less, more preferably 200 or less, and even more preferably 150 or less. This can efficiently improve the stability of the asphalt composition. Therefore, the average number of moles added is preferably 20 to 300, or 25 to 300, more preferably 30 to 200, and even more preferably 35 to 150. The above-mentioned average number of moles added is a guideline, and regardless of whether the above-mentioned range is satisfied, the alkylene oxide chain may contain one in which alkylene oxide units are not repeatedly added (monoalkylene oxide group).

[0021] The polyalkylene oxide chain may be composed of one type of alkylene oxide group alone or two or more types of alkylene oxide groups. In a polyalkylene oxide chain composed of two or more types of alkylene oxide groups, the addition form of each alkylene oxide group may be random, block, or a mixture thereof. The terminal unit of the polyalkylene oxide chain is usually a hydroxyl group, but is not limited thereto, and may be an alkyl ether or a carboxylic acid ester as long as it does not interfere with bonding with the lignosulfonic acid compound.

[0022] Examples of aromatic water-soluble compounds having an alkylene oxide chain include oxyalkylene group adducts to aromatic compounds such as phenol, cresol, nonylphenol, naphthol, methylnaphthol, butylnaphthol, bisphenol A, and bisphenol S. More specifically, examples include polyalkylene oxide alkylphenyl ethers, polyalkylene oxide phenyl ethers, polyalkylene oxide alkylnaphthyl ethers, and polyalkylene oxide naphthyl ethers. Among these, benzene ring derivatives are preferred because they can exhibit good co-condensation properties, and at least one of polyalkylene oxide alkylphenyl ethers and polyalkylene oxide phenyl ethers is more preferred, with polyalkylene oxide phenyl ethers (particularly, oxyalkylene group adducts to phenol) (e.g., poly(ethylene oxide) monophenyl ether, poly(propylene oxide) monophenyl ether, and the preferred ranges of the average added mole numbers of ethylene oxide units and propylene oxide units are as described above) being even more preferred. The aromatic water-soluble compound having an alkylene oxide chain may be used alone or in combination of two or more.

[0023] (Aromatic Water-Soluble Compound Having a Carboxyl Group) Examples of aromatic water-soluble compounds having a carboxyl group include naphthalene ring or benzene ring derivatives having at least one carboxyl group. More specific examples include isophthalic acid, oxynaphthoic acid, benzoic acid, hydroxybenzoic acid, and isomers thereof. Due to their good reactivity, o-hydroxybenzoic acid, m-hydroxybenzoic acid, and p-hydroxybenzoic acid are preferred, with p-hydroxybenzoic acid being more preferred. The aromatic water-soluble compound having a carboxyl group may be one type or a combination of two or more types.

[0024] (Aromatic water-soluble compound having a sulfo group) Examples of aromatic water-soluble compounds having a sulfo group include alkylnaphthalenesulfonic acid, alkylphenolsulfonic acid, aniline sulfonic acid, and alkylbenzenesulfonic acid. More specifically, examples include naphthalenesulfonic acid, methylnaphthalenesulfonic acid, butylnaphthalenesulfonic acid, phenolsulfonic acid, cresolsulfonic acid, aniline sulfonic acid, benzenesulfonic acid, toluenesulfonic acid, and isomers and condensates thereof. Examples of condensates include naphthalenesulfonic acid-formaldehyde condensates. Because of their good reactivity, phenol derivatives and aniline sulfonic acid having a sulfo group are preferred, phenolsulfonic acid and aniline sulfonic acid are more preferred, and aniline sulfonic acid is even more preferred. The aromatic water-soluble compound having a sulfo group may be one type or a combination of two or more types.

[0025] (Other Aromatic Water-Soluble Compounds) Examples of other aromatic water-soluble compounds include aromatic water-soluble compounds that do not have any of an alkylene oxide chain, a carboxyl group, or a sulfo group, such as (alkyl)phenols such as phenol and cresol. The other aromatic water-soluble compounds may be used alone or in combination of two or more.

[0026] The aromatic water-soluble compound contains at least an aromatic water-soluble compound having an alkylene oxide chain, and more preferably, only an aromatic water-soluble compound having an alkylene oxide chain, or a combination of such a compound with an aromatic water-soluble compound having a carboxyl group and / or an aromatic water-soluble compound having a sulfo group.

[0027] The structural unit (II) may be a structural unit derived from one type of aromatic water-soluble compound, or may be a structural unit derived from two or more types. The aromatic water-soluble compound may be a single type or a combination of two or more types, and is preferably an aromatic water-soluble compound having an alkylene oxide chain alone, or a combination of such a compound with an aromatic water-soluble compound having a carboxyl group and / or an aromatic water-soluble compound having a sulfo group.

[0028] -Other structural unit (III)- The lignin derivative compound may have a structural unit (III) other than the structural units (I) and (II). Examples include aromatic compounds other than water-soluble aromatic compounds (e.g., simple aromatic hydrocarbon compounds such as benzene and naphthalene), (poly)alkylene glycol alkenyl ether compounds; and structural units derived from water-soluble polyalkylene glycols, polyoxyalkylene compounds, polycarboxylic acid compounds, and polyester compounds, both of which have hydrogen atoms at both ends (e.g., polymer blocks described in WO 2018 / 56124). The structural unit (III) may be one type or a combination of two or more types.

[0029] [1.2 Composition Ratio of Each Structural Unit of Lignin Derivative Compound] The weight ratio (I) / (II) of structural unit (I) to structural unit (II) is usually 1 / 99 to 99 / 1, preferably 2 / 98 to 90 / 10, more preferably 5 / 95 to 70 / 30, or 10 / 90 to 70 / 30, and even more preferably 15 / 85 to 70 / 30 or 20 / 80 to 60 / 40 (the total of (I) and (II) being 100% by weight).

[0030] When the structural unit (III) is contained, the weight proportion thereof is generally 5% by weight or less, preferably 3% by weight or less, and more preferably 2% by weight or less, relative to 100% by weight of the total of (I) and (II).

[0031] (I) / (II) is defined as (weight of solids of lignosulfonic acid compound before reaction) / (weight of solids of aromatic water-soluble compound before reaction) in the reaction between a lignosulfonic acid compound and a water-soluble aromatic compound, and is measured by this method in the examples described later.

[0032] When the structural unit (II) contains a structural unit derived from a compound other than an aromatic water-soluble compound having an alkylene oxide chain, the proportion of the structural unit derived from an aromatic water-soluble compound having an alkylene oxide chain in the structural unit (II) is usually 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, and even more preferably 80% by weight or more. There is no particular upper limit, as long as it is 100% by weight or less.

[0033] The weight ratio of each of the constituent units corresponds to the ratio of each compound as a raw material used at the start of the reaction.

[0034] [1.3 Salts of Lignin Derivative Compounds] The lignin derivative compound may be any reaction product obtained by the above-described reaction, and may be either a free acid or a neutralized salt thereof. Neutralized salts are preferred because they facilitate storage and use of the polymer. Examples of neutralized salts of the reaction product include alkali metal salts such as sodium salts or potassium salts; alkaline earth metal salts such as calcium salts; ammonium salts; and salts of organic amines.

[0035] [1.4 Physical Properties of Lignin Derivative Compound] The lignin derivative compound preferably has the following physical properties.

[0036] -Weight-average molecular weight- The weight-average molecular weight of the lignin derivative compound is not particularly limited, but is preferably 1,000 to 500,000, more preferably 2,000 to 300,000, and even more preferably 5,000 to 200,000. The weight-average molecular weight in the present invention can be measured by a known method using gel permeation chromatography (GPC) in terms of polyethylene glycol.

[0037] The following conditions are exemplified as measurement conditions for GPC. The values ​​measured in the examples below are also measured under these conditions. Measurement device: manufactured by Tosoh Corporation Column used: Shodex Column OH-pak SB-806HQ, SB-804HQ, SB-802.5HQ Eluent: 0.05 mM sodium nitrate / acetonitrile 8 / 2 (v / v) Standard substance: polyethylene glycol (manufactured by Tosoh Corporation or GL Sciences Corporation) Detector: differential refractometer (manufactured by Tosoh Corporation)

[0038] -Peak Area Ratio of High Molecular Weight Component- The peak area ratio of the high molecular weight component of the lignin derivative compound is usually 80% or more, preferably 85% or more. The upper limit is 99% or less, more preferably 97% or less. By being within this range, the structural units (I) and (II) in the lignin derivative compound are present in a balanced manner, and the effect of improving physical properties such as viscosity reduction of the asphalt composition can be further enhanced. In this specification, the peak area ratio of the high molecular weight component means the ratio of the peak area value of components having a weight average molecular weight of 1,200 or more to the peak area of ​​all components in a chart obtained by gel permeation chromatography (GPC) measurement of the lignin derivative compound using UV (detection wavelength 280 nm), and can be calculated using the following formula: Peak Area Ratio of High Molecular Weight Component = (area value of high molecular weight component in GPC chart (280 nm)) / (area value of all components in GPC chart (280 nm)) The detector is not particularly limited, but an ultraviolet absorption detector (manufactured by Tosoh Corporation) can be used as an example.

[0039] The method for determining each area value will be described with reference to the GPC chart in Figure 1. In Figure 1, point (1) is the elution start point, point (2) is the elution end point, and point (3) is the value corresponding to a weight-average molecular weight of 1,200. The area value of the high molecular weight component in the above formula is the intersection of the line connecting point (1) and point (2) (baseline: dotted line in Figure 1) and . The area value of all components means the area enclosed by the line connecting point (1) and point (2) (baseline: dotted line in Figure 1) and the curve from point (1) to point (2). The peak area value of a component having a weight-average molecular weight of 1,200 or more means the area enclosed by the line extending from point (1) to point (3) of the baseline, the line extending perpendicular to the baseline from point (3) (dash-dotted line in Figure 1), and the curve. The GPC measurement conditions can be the same as those used for measuring the weight-average molecular weight described above.

[0040] - Thermal Weight Loss Rate - The lower limit of the thermal weight loss rate of the lignin derivative compound is usually 50% or more, preferably 55% or more, and more preferably 60% or more. At 50% or more, the ash content is low, which suppresses the inhibition of the effects of the present invention by inevitable impurities other than the lignin derivative compound, ensuring good effects. The upper limit is 85% or less, preferably 80% or less, and more preferably 75% or less. At 85% or less, heat resistance can be ensured. Therefore, the thermal weight loss rate measured by TG-DTA is 50 to 85%, preferably 55 to 80%, and more preferably 60 to 75%. When granules containing a lignin derivative compound are used as an additive for asphalt compositions, it is preferable that the above thermal weight loss rate is satisfied.

[0041] - Thermal decomposition point - The lower limit of the thermal decomposition point of the lignin derivative compound is preferably 350 ° C or higher, more preferably 360 ° C or higher, and even more preferably 370 ° C or higher. When it is 350 ° C or higher, heat resistance can be ensured. Furthermore, the upper limit is less than 400 ° C, preferably 398 ° C or lower, more preferably less than 395 ° C or 394 ° C or lower. When it is less than 400 ° C, resinification of the granular composition is suppressed, and the effects of the present invention can be better exhibited. Therefore, the thermal decomposition point measured by TG-DTA is preferably 350 ° C or higher and less than 400 ° C, more preferably 360 to 398 ° C, and even more preferably 370 to less than 395 ° C or 394 ° C or lower. When a granule containing a lignin derivative compound is used as an additive for an asphalt composition, it is preferable to satisfy the above-mentioned thermal weight loss rate.

[0042] The thermal decomposition point and the rate of thermal weight loss can be measured using a thermogravimetric differential calorimeter (TG-DTA). An example of the method for measuring a granular material is as follows. A sample is prepared by drying and solidifying 10 g of a granular composition of a lignin derivative compound sample (which may contain compounds (i) and (ii)). Methods for drying and solidifying include: 1) a method of drying and solidifying at 105°C for one day using a dryer (trade name "Air-Blowing Constant Temperature Incubator DKM600", manufactured by Yamato Scientific Co., Ltd.); 2) a method of drying and solidifying at -20°C for one day using a freeze dryer (trade name "FDU-1200", manufactured by Tokyo Rikakikai Co., Ltd.); 3) a method of drying and solidifying at 180°C using a spray dryer (e.g., trade name "TR120", manufactured by Pris Co., Ltd.); and 4) a method using a drum dryer (e.g., manufactured by Katsuragi Kogyo Co., Ltd.). Approximately 10 mg of the solidified sample is then heated in a nitrogen atmosphere from 50°C to 600°C at a heating rate of 10°C / min. The temperature at which the weight loss rate of the sample is at its maximum is taken as the thermal decomposition point, and the weight loss rate up to 600°C is taken as the thermal weight loss rate.

[0043] -Melting Point- The upper limit of the melting point of the lignin derivative compound is usually 70°C or lower or 65°C or lower, preferably 60°C or lower, and more preferably 55°C or lower. This ensures good compatibility with asphalt and can suppress an increase in viscosity after mixing with asphalt. The lower limit is not particularly limited, but is, for example, 25°C or higher or 30°C or higher. The melting point can be measured using a DSC measurement device.

[0044] -Average particle size- When a granular material containing a lignin derivative compound is used as an additive for an asphalt composition, the average particle size is preferably 30 μm or more. The upper limit is preferably 250 μm or less. The average particle size is the value at which the cumulative distribution reaches 50% based on the molecular weight distribution obtained by measuring 3 g of a powder sample under dry conditions using a laser diffraction particle size distribution analyzer (Mastersizer 3000 (manufactured by Malvern)), with the horizontal axis representing particle size (μm) and the vertical axis representing volume (%).

[0045] -Surface Tension- When a liquid containing a lignin derivative compound is used as an additive for an asphalt composition, the surface tension of a solution having a non-volatile content of 10% at 100°C is preferably 25 dyne / cm or more, more preferably 27 dyne / cm or more, and even more preferably 29 dyne / cm or more. The upper limit is preferably 55 dyne / cm or less, more preferably 50 dyne / cm or less, and even more preferably 45 dyne / cm or less. The definition of "non-volatile content at 100°C" is the same as that for B-type viscosity. "A solution having a non-volatile content of 10%" refers to an aqueous solution having a non-volatile content of the lignin derivative of 8 to 12%. The surface tension can be measured using a surface tensiometer (for example, a CBVP-A3 manufactured by Kyowa Interface Science Co., Ltd.).

[0046] The above physical properties can be adjusted by appropriately adjusting the types and amounts of the lignosulfonic acid compound, water-soluble compound, and lignin derivative. In particular, when a lignin derivative is included, the properties can be adjusted by appropriately designing the reaction conditions for the lignin derivative. More specifically, the properties can be adjusted by appropriately changing the type and amount of the reaction initiator, the concentration of the reaction solution, the ratio of the lignosulfonic acid compound to the water-soluble compound, the type and amount of side chain functional groups of the water-soluble compound, the reaction temperature, the reaction time, etc.

[0047] [1.5 Method for Producing Lignin Derivative Compound] The preparation of a lignin derivative compound may be carried out by reacting raw material compounds including a lignosulfonic acid compound (hereinafter sometimes referred to as compound (i)) and a water-soluble aromatic compound (hereinafter sometimes referred to as compound (ii)). For example, a method of reacting a lignosulfonic acid compound with a water-soluble aromatic compound may be mentioned. More specifically, for example, a method of condensing a water-soluble aromatic compound with a lignosulfonic acid compound (e.g., formaldehyde condensation), a radical reaction, or an ionic bonding method may be mentioned. For example, a formaldehyde condensation method may be a method of adding formaldehyde to a lignosulfonic acid compound and bonding it with a water-soluble aromatic compound. For example, a radical reaction method may be a method of abstracting a hydrogen radical by reacting a radical initiator with a lignosulfonic acid compound, and then radically reacting the generated radical with at least one water-soluble aromatic compound.

[0048] The method for producing the lignosulfonic acid compound as a raw material is not particularly limited, and it can be produced, for example, by extracting it from the waste liquor of sulfite pulp obtained by cooking wood under acidic conditions. Furthermore, a powdered product that has undergone a drying process such as powder drying may also be used. The powder form makes it easy to handle.

[0049] The lignosulfonic acid compound may be a commercially available product, such as Vanilex HW (manufactured by Nippon Paper Industries Co., Ltd.), Sunex M (manufactured by Nippon Paper Industries Co., Ltd.), Pearlex NP (manufactured by Nippon Paper Industries Co., Ltd.), or Sunflow RH (manufactured by Nippon Paper Industries Co., Ltd.) The lignosulfonic acid compound may be in the form of a salt such as a monovalent metal salt, a divalent metal salt, an ammonium salt, or an organic ammonium salt (preferably a monovalent metal salt or a divalent metal salt, more preferably a calcium salt, a magnesium salt, a sodium salt, or a calcium-sodium mixed salt).

[0050] The reaction temperature between the lignosulfonic acid compound and the aromatic compound may be appropriately set depending on the solvent used, and is not particularly limited, but is usually 0 to 200° C., preferably 45 to 150° C. When a low-boiling compound is used as the reaction solvent, it is preferable to carry out the reaction under pressure using an autoclave in order to improve the reaction rate.

[0051] The reaction between the lignosulfonic acid compound and the aromatic water-soluble compound may be either a solution reaction or a bulk reaction. In the case of a solution reaction, a solvent may be used. Examples of the solvent include water; alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as cyclohexane and n-hexane; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; and cyclic ethers such as tetrahydrofuran and dioxane. Among these, water and / or lower alcohols are preferred, with water being more preferred. This improves the solubility of the raw material monomers and the resulting copolymer, and also eliminates the need for a solvent removal step. The solvent may be used alone or in combination (e.g., a water-alcohol mixed solvent).

[0052] An antifoaming agent may be used during the preparation of the lignin derivative. This can suppress foaming during the reaction, allowing for a uniform reaction system. Examples of antifoaming agents include those containing a nonionic surfactant as an active ingredient.

[0053] The reaction conditions for preparing the lignin derivative compound can be adjusted as needed. The progress of the reaction is characterized by a clear increase in viscosity. When the desired viscosity is reached, the reaction can be stopped by cooling or neutralization.

[0054] In preparing the lignin derivative compound, the addition of water may be adjusted to control the condensation viscosity and condensation time. The pH during the reaction may also be adjusted to an appropriate value. The reaction is typically carried out under acidic conditions. If the reaction system is already acidic due to the aromatic compound having a sulfo group and the unreacted acid contained therein, the reaction may be carried out in the acidic range. If the reaction system is not acidic, the reaction may be carried out by adding an acid catalyst such as hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, or p-toluenesulfonic acid in advance. A preferred acid is sulfuric acid, but other acids may also be used, and the acid is not limited thereto.

[0055] The reaction rate of the water-soluble aromatic compound is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. A reaction rate of 50% or more can further improve the stability of the asphalt composition.

[0056] The reaction rate of the water-soluble aromatic compound can be measured as follows, and this method is also used in the examples described below. First, in GPC measurement using UV (detection wavelength 280 nm), the peak areas before and after the reaction are compared. Next, when the peak area before the reaction (i.e., the peak area of ​​the peak corresponding to the water-soluble aromatic compound) is [b] and the peak area after the reaction is [a], the reaction rate can be calculated using the formula: ([b] - [a]) / [b]. The GPC measurement conditions can be the same as those used for measuring the weight-average molecular weight described above.

[0057] If necessary, the reaction solution after the condensation reaction may be subjected to post-treatments such as heat treatment at a temperature of 60 to 120°C under a pH of 8.0 to 13.0, neutralization treatment, or treatment of adjusting the pH of the reaction solution (e.g., to 1.0 to 4.0, preferably 1.5 to 2.0) to precipitate the reaction product as a solid. Post-treatments are typically carried out continuously for approximately 10 minutes to 3 hours. This significantly reduces the aldehyde content (e.g., formaldehyde content) of the reaction solution. In addition to or instead of the removal of free formaldehyde by the so-called Cannizzaro reaction, other methods for reducing excess formaldehyde may also be used, such as those known in the field of melamine-formaldehyde resin and phenol-formaldehyde resin chemistry. Examples of such methods include the addition of a formaldehyde absorber (such as a small amount of sodium bisulfite or hydrogen peroxide).

[0058] In the case of a treatment in which the pH of the reaction solution is adjusted to precipitate the reaction product as a solid, the supernatant salt solution is then separated and removed, and the remaining free reaction product, which is mostly salt-free, is redissolved in an amount of water sufficient to obtain the desired solid concentration, thereby obtaining the lignin derivative.

[0059] The neutralization treatment can be carried out using a neutralizing agent capable of neutralizing the reaction product and the catalyst. Examples of the neutralizing agent include sodium hydroxide, calcium hydroxide, and Ba(OH). ２ Examples of suitable basic compounds include those containing methyl methyl acrylate and methyl methacrylate, such as methyl methacrylate, ...

[0060] When by-products such as sodium sulfate, calcium sulfate, and hydrates thereof are generated during the addition and neutralization of the basic compound, it is preferable to add the basic compound in a heated state after the reaction and maintain the heated state to improve the removability of the by-products. Heating is preferably performed to 40°C or higher. The heated state is preferably maintained for 30 minutes or longer. After the reaction is completed, the concentration, pH, etc. of the obtained lignin derivative compound may be adjusted as necessary.

[0061] [1.6 Optional Components] The asphalt additive may contain optional components other than the lignin derivative compound, such as anti-exfoliation components other than the copolymer, solvents, antioxidants, heat stabilizers, light stabilizers, UV absorbers, flame retardants, plasticizers, pigments, dyes, dye dispersants, chelating agents, and unreacted compounds (i) and (ii).

[0062] [1.7 Formulation] The formulation of the asphalt additive is not particularly limited. For example, it may be granular (solid such as powder or pellet) or liquid (including gel). Examples of methods for forming into granules include a method of drying a lignin derivative compound (including optional components as necessary). Drying methods include, for example, a method of neutralizing with a hydroxide of a divalent metal such as calcium or magnesium to form a polyvalent metal salt and then drying; a method of supporting the compound on an inorganic powder such as silica-based fine powder and drying; a method of drying and solidifying the compound into a thin film on a support of a drying device (e.g., a drum-type drying device, a disk-type drying device, or a belt-type drying device); and a method of drying and solidifying the compound using a spray dryer. Of these, drying methods using a drying device are preferred, and drying methods using a disk-type drying device or a drum-type drying device are more preferred. Alternatively, a method using a pulverizer after drying with a drying device may be used. This makes it easier to adjust the particle size, and adjusting to a predetermined particle size (e.g., 250 μm or less) can make the compound more compatible with asphalt. The grinding device is not particularly limited, but examples thereof include a hammer mill, a pin mill, a rotary mill, a vibration mill, a roller mill, a cutter mill, etc. On the other hand, examples of methods for preparing a liquid include a method in which the above-mentioned drying treatment is not carried out after the preparation of the lignin derivative compound, and a method in which the above-mentioned drying treatment is carried out, and then the lignin derivative compound is dissolved in an arbitrarily selected solvent and stirred as necessary to prepare a solution, suspension, dispersion, or gel.

[0063] [2. Asphalt Additives] By adding a lignin derivative compound to an asphalt composition or an asphalt emulsion composition, the compound can be melted with asphalt at relatively low temperatures and can provide effects such as viscosity reduction. Therefore, the compound can be used as an additive for asphalt compositions or asphalt emulsion compositions.

[0064] [2.1 Asphalt Composition] An asphalt composition (asphalt mixture, asphalt mixture) typically contains asphalt and aggregate. The asphalt composition is typically used in at least one of the surface course and the base course of an asphalt pavement (surface course, base course, and subgrade).

[0065] Asphalt Asphalt (bituminous material) may be any of straight asphalt and modified asphalt (polymer modified asphalt, semi-blown asphalt, hard asphalt).

[0066] -Aggregate- Asphalt compositions typically contain aggregate. Examples of aggregates include crushed stone, crushed rock, boulders, gravel, sand, crusher run, recycled aggregate, and ceramics. Aggregates typically contain a combination of fine and coarse aggregates. Examples of fine aggregates include relatively small aggregates (e.g., aggregates with a particle size of 2.36 mm or less and 0.075 mm or more) such as river sand, dune sand, mountain sand, sea sand, crushed sand, fine sand, screenings, crushed stone dust, silica sand, artificial sand, glass cullet, foundry sand, and crushed recycled aggregate sand. Examples of coarse aggregates include relatively large aggregates (e.g., aggregates with a particle size greater than 2.36 mm) such as crushed stone. The aggregate may also be recycled asphalt aggregate (e.g., crushed and decomposed used asphalt). The aggregate may further contain a filler (aggregates smaller than fine aggregate, e.g., aggregates with a particle size less than 0.075 mm). The particle size of the aggregate can be measured in accordance with the definition of particle size in JIS A5001: 1995. The weight ratio of the fine aggregate, coarse aggregate and filler is not particularly limited.

[0067] Components Other Than Asphalt and Aggregate The asphalt composition may contain components other than asphalt and aggregate, such as fillers (e.g., stone powder), emulsifiers, solvents (e.g., water), pigments, synthetic rubber, anti-agglomerating agents, fluidizing agents, plasticizers, electrolytes, and anti-adhesion agents.

[0068] [2.2 Asphalt Emulsion Composition] In this specification, an asphalt emulsion composition is a composition containing asphalt, an emulsifier, and a solvent. In an asphalt emulsion composition, asphalt is usually dispersed in a solvent, and the dispersed state can preferably be maintained at room temperature (e.g., 5 to 80°C). The asphalt emulsion composition can be used for surface treatment of each layer in an asphalt pavement (to improve properties such as adhesion and waterproofing). The asphalt that can be contained in the asphalt emulsion composition is as explained in the asphalt composition.

[0069] -Emulsifier- Any of cationic, anionic, nonionic, and amphoteric emulsifiers can be used as the emulsifier contained in the asphalt emulsion. Among these, cationic emulsifiers are preferred from the viewpoint of better exerting the effects of the present invention.

[0070] Examples of cationic emulsifiers include primary amines, secondary amines, tertiary amines, quaternary ammonium salts, and polyamines, and specific examples include amines such as alkyl (poly)amines (e.g., alkyl monoamines, alkyl diamines, and alkyl triamines), amidoamines, alkyl polyamines, alkyl imidazolines, hydroxyalkyl amines, and rosin amines, as well as salts thereof (e.g., mineral acid salts (e.g., hydrochlorides), lower carboxylates, sulfamates, and quaternary ammonium salts). As the cationic emulsifier, alkyl amines or salts thereof are preferred, and (hardened) beef tallow diamine or salts thereof (e.g., hydrochloride) are more preferred.

[0071] Examples of the anionic emulsifier include fatty acids, alkyl sulfates, alkyl ether sulfates, alkylbenzenesulfonic acids, naphthalenesulfonic acids, alkylnaphthalenesulfonic acids, melaminesulfonic acids, rosin acids, alkylphosphoric acids, and salts thereof.

[0072] Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, oxyethylene-oxypropylene block polymers, sorbitan fatty acid esters, alkylene oxide adducts of sorbitan esters, polyoxyethylene sorbitan fatty acid esters, polyethylene glycol fatty acid esters, alkyl glycosides, and polyoxyethylene alkylamines.

[0073] Examples of amphoteric emulsifiers include betaine-type emulsifiers such as betaine acetate, amidobetaine, sulfobetaine, and imidazolium betaine, aminated lignin, and amine oxide.

[0074] -Acid- The asphalt emulsion composition may contain an acid together with the emulsifier, and when a cationic emulsifier is contained, it is preferable to further contain an acid. This makes it possible to adjust the pH of the composition and improve its performance as an emulsion. Examples of acids include hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, acetic acid, and glycolic acid, and hydrochloric acid and phosphoric acid are preferred, and hydrochloric acid is more preferred.

[0075] The solvent may be any solvent capable of maintaining the asphalt in a dispersed state. Examples include water and organic solvents. Examples of organic solvents include alcohols such as methanol, ethanol, isopropanol, and alkylene glycols; ketones such as acetone and methyl ethyl ketone; alkylene glycol esters / ethers / amides; and combinations of two or more of these. Water or a combination of water and an organic solvent is preferred.

[0076] [2.2 Amount Used] The effective amount of the asphalt additive relative to the asphalt contained in the asphalt composition or asphalt emulsion composition, converted into the amount of lignin derivative compound, is usually 0.0001 wt% or more, 0.01 wt% or more, or 0.05 wt% or more, preferably 0.1 wt% or more, and more preferably 0.3 wt% or more. The upper limit is usually 30 wt% or less, preferably 20 wt% or less, and more preferably 15 wt% or less.

[0077] The amount of aggregate in the asphalt composition (assumed to be 100% by weight) is usually 70% by weight or more, preferably 75% by weight or more, and more preferably 80% by weight or more. The upper limit is usually 97% by weight or less, preferably 95% by weight or less, and more preferably 90% by weight or less. By keeping the amount in this range, the durability of the pavement laminate can be improved.

[0078] The content of asphalt is preferably 30 to 65 mass %, more preferably 35 to 65 mass %, and even more preferably 40 to 65 mass %, based on the asphalt composition (100 parts by weight).

[0079] The content of the emulsifier in the asphalt emulsion composition (when an acid is further contained, the total amount of the acid and emulsifier) ​​is preferably 0.1 to 15 mass%, more preferably 0.5 to 10 mass%, and even more preferably 1 to 10 mass%, relative to the asphalt emulsion composition (100% by weight). When the emulsifier content is within this range, aggregation of the asphalt emulsion can be suppressed, and mixability with aggregate can be further improved.

[0080] [2.3 Method for Producing Asphalt Composition] An asphalt composition can be produced by adding all or successively the raw materials constituting the asphalt composition (asphalt, additives, aggregate, and optional components) and mixing them. Mixing is usually carried out under heated conditions. The heating temperature is usually high, for example, 120°C or higher, preferably 130°C or higher. The upper limit is usually 220°C or lower, preferably 200°C or lower. If the asphalt additive contains moisture, it is preferable to dry it before adding it. On the other hand, when producing an asphalt composition using an asphalt emulsion composition, the asphalt composition can be produced by adding all or successively the asphalt emulsion composition, aggregate, additives, and optional components at room temperature (usually 5 to 80°C, 15 to 50°C).

[0081] [2.4 Pavement] The asphalt composition can be used to form a pavement. A pavement typically has a layered structure including, from bottom to top, a roadbed, a base layer, and a surface layer. A layer containing an asphalt emulsion composition may be formed on the surface of the surface layer, between the surface layer and the base layer, and / or between the base layer and the roadbed. Examples of methods for producing a pavement laminate include forming a base layer on the surface of the roadbed and then forming a surface layer on the base layer, as follows: First, a roadbed is formed by digging down the road surface and laying sand on top of the roadbed, and then crushed stone, gravel, etc. are laid on top of the roadbed. The roadbed may be formed in two layers, for example, by laying large crushed stone to form a lower roadbed, and then laying relatively small crushed stone to form an upper roadbed. During roadbed formation, compaction may be performed using equipment such as a rolling vehicle, if necessary. Subsequently, a base layer is formed on the roadbed. The base layer can be formed, for example, by spreading a heated asphalt composition on the roadbed and, if necessary, compacting it using equipment such as a rolling vehicle. Subsequently, a surface layer is formed on the base layer. The surface layer can be formed, for example, by spreading a heated asphalt composition on the base layer and, if necessary, compacting it using equipment such as a rolling vehicle. It is preferable to maintain a high temperature during the work of forming the base layer and the surface layer. The heating temperature is usually 120°C or higher, preferably 140°C or higher. The upper limit is usually 220°C or lower, preferably 200°C or lower. When a layer containing an asphalt emulsion composition is formed, for example, after the roadbed, base layer, or surface layer is formed, the asphalt emulsion composition is sprayed on the surface of the layer, and, if necessary, cured with aggregate such as sand, and then an upper layer is constructed in sequence.

[0082] Examples 1 to 5 and Comparative Examples 1 to 3 (1-1) Preparation of Lignin Sulfonate a-1 Wood derived from Radiata pine was subjected to sulfite cooking using SO ２ The composition was subjected to sulfite treatment at 140°C and pH 2 for 3 hours using a magnesium sulfite solution with a concentration of 4 g / 100 mL, and the resulting composition was filtered. The filtrate was adjusted to pH 5.0 with an aqueous sodium hydroxide solution and spray-dried using a spray dryer to obtain a powder of lignin sulfonate a-1.

[0083] (1-2) Preparation of Lignin Sulfonate a-2 Wood derived from Radiata pine was extracted with SO based on the sulfite cooking method. ２ A sulfite treatment was carried out for 3 hours at 140°C and pH 2 using a magnesium sulfite solution with a concentration of 4 g / 100 mL, and a magnesium hydroxide solution was added to the resulting composition so that the solid content was 9 wt %, followed by holding for 4 hours at 90°C. Next, oxygen was blown in for 2 hours for oxygen treatment, after which the pH was adjusted to 7.0 and spray-dried using a spray dryer to obtain a powder of lignin sulfonate a-2.

[0084] (1-3) Preparation of lignin sulfonate a-3 Wood derived from Radiata pine was subjected to sulfite cooking. ２ The composition was subjected to sulfite treatment at 140°C and pH 2 for 3 hours using a magnesium sulfite solution with a concentration of 4 g / 100 mL, and the resulting composition was filtered. The filtrate was adjusted to pH 5.0 with an aqueous sodium hydroxide solution, concentrated using a polysulfone-based ultrafiltration membrane with a molecular weight cutoff of 20,000, and spray-dried using a spray dryer to obtain a powder of lignin sulfonate a-3.

[0085] (2) Preparation of lignin derivative (2-1) Preparation of lignin derivative compound (1) Thermometer, stirrer, reflux device, and a glass reaction vessel equipped with a dropping device, 106 g of water, 45 g of lignin sulfonate a-1 as compound (i), 55 g of poly (ethylene oxide) monophenyl ether (average number of moles of ethylene oxide added 50) as compound (ii), 8 g of 37% aqueous formaldehyde solution, 37 g of 72% sulfuric acid, 0.05 g of Pronal 753 (manufactured by Toho Chemical Co., Ltd.) as a defoaming agent was added, and the mixture was stirred while heating, and the reaction was completed by stirring at 105 ° C. for 10 hours. To the resulting aqueous solution, 70 g of a 250 g / L calcium hydroxide aqueous solution was added, and after stirring for 1 hour, the resulting gypsum was removed by filtration, and the pH was adjusted with aqueous sodium hydroxide solution to obtain a liquid lignin derivative compound (1). This liquid was dried at 140° C. using a drum dryer (manufactured by Katsuragi Kogyo Co., Ltd.) and then pulverized using an extreme mill to obtain a dried product of lignin derivative compound (1).

[0086] The weight ratio of the constituent units contained in the obtained lignin derivative compound (1) was (I) / (II) = 45 / 55, the peak area ratio of the high molecular weight component was 91%, the reaction rate of compound (i) with compound (ii) was 80%, and the weight average molecular weight of the lignin derivative compound (1) was 59,000.

[0087] (2-2) Preparation of lignin derivative compound (2) Thermometer, stirrer, reflux device, and a glass reaction vessel equipped with a dropping device, 200 g of water, compound (i) as lignin sulfonate a-130 g, compound (ii) as poly (ethylene oxide) monophenyl ether (average addition moles of ethylene oxide 25) 70 g, 37% formaldehyde aqueous solution 10 g, 72% sulfuric acid 40 g, Pronal 753 (manufactured by Toho Chemical Co., Ltd.) 0.05 g as a defoaming agent was added, and the mixture was stirred while heating, and the reaction was completed by stirring at 105 ° C. for 10 hours. To the resulting aqueous solution, 80 g of a 250 g / L calcium hydroxide aqueous solution was added, and after stirring for 1 hour, the resulting gypsum was removed by filtration, and the pH was adjusted with aqueous sodium hydroxide solution to obtain a liquid of lignin derivative compound (2). This liquid was dried at 140° C. using a drum dryer (manufactured by Katsuragi Kogyo Co., Ltd.) and then pulverized using an extreme mill to obtain a dried product of lignin derivative compound (2).

[0088] The weight ratio of the structural units contained in the obtained lignin derivative compound (2) was (I) / (II) = 30 / 70, the peak area ratio of the high molecular weight component was 94%, the reaction rate of compound (i) with compound (ii) was 80%, and the weight average molecular weight of lignin derivative compound (2) was 55,000. (2-3) Preparation of Lignin Derivative Compound (3)

[0043] Into a glass reaction vessel equipped with a thermometer, a stirrer, a reflux device, and a dropping device, 90 g of water, 198 g of Sunflow RH (lignin sulfonate, manufactured by Nippon Paper Industries Co., Ltd.) as compound (i), 75 g of poly(ethylene oxide) monophenyl ether (average number of moles of ethylene oxide added: 37) as compound (ii), 10 g of a 37% aqueous formaldehyde solution, and 61 g of a 72% aqueous sulfuric acid solution were charged, and the mixture was heated and stirred, and maintained at 105°C for 3 hours to complete the reaction. To the resulting aqueous solution, 127 g of a 250 g / L calcium hydroxide aqueous solution was added to a reaction vessel. After stirring for 1 hour, the mixture was filtered to remove the gypsum produced by neutralization. The pH was then adjusted with a sodium hydroxide aqueous solution to obtain a liquid lignin derivative compound (3) containing a copolymer with a weight-average molecular weight of 29,500. The weight ratio of each structural unit contained in the resulting lignin derivative compound (3) was (I) / (II) = 50 / 50, and the reaction rate of the aromatic water-soluble compound was 59%. The peak area ratio of the high molecular weight component of the resulting lignin derivative compound (3) was 87%.

[0089] (2-4) Preparation of lignin derivative compound (4) Thermometer, stirrer, reflux device, and a glass reaction vessel equipped with a dropping device, 212 g of water, 90 g of lignin sulfonic acid a-2 as compound (i), 124 g of poly (ethylene oxide) monophenyl ether (average addition moles of ethylene oxide 50) as compound (ii), 17 g of 37% aqueous formaldehyde solution, 74 g of 72% aqueous sulfuric acid solution, 0.05 g of Pronal 753 (manufactured by Toho Chemical Co., Ltd.) as a defoaming agent was added, and the mixture was stirred while heating, and the reaction was completed by holding at 105 ° C. for 3 hours. To the resulting aqueous solution, 140 g of 250 g / L aqueous calcium hydroxide solution was added to the reaction vessel, and after stirring for 1 hour, the mixture was filtered to remove the gypsum produced by neutralization, and then the pH was adjusted with aqueous sodium hydroxide solution to obtain a liquid of lignin derivative compound (4) containing a copolymer of weight average molecular weight 47,600.

[0090] This liquid was dried at 140° C. using a drum dryer (manufactured by Katsuragi Kogyo Co., Ltd.) and then pulverized using an extreme mill to obtain a dried product of lignin derivative compound (4).

[0091] The weight ratio of the structural units contained in the obtained lignin derivative compound (4) was (I) / (II)=42 / 58, and the reaction rate of the aromatic water-soluble compound was 77%. The peak area ratio of the high molecular weight component of the obtained lignin derivative compound (4) was 90%.

[0092] (2-5) Preparation of lignin derivative compound (5) Thermometer, stirrer, reflux device, and a glass reaction vessel equipped with a dropping device, 305 g of water, 25 g of lignin sulfonate a-3 as compound (i), 37 g of poly (ethylene oxide) monophenyl ether (average addition moles of ethylene oxide 47 moles) as compound (ii), 6 g of 37% aqueous formaldehyde solution, 22 g of 72% aqueous sulfuric acid solution, 0.02 g of Pronal 753 (manufactured by Toho Chemical Co., Ltd.) as a defoamer, and stirred while heating, and the reaction was completed by holding at 105 ° C. for 16 hours. To the resulting aqueous solution, 45 g of a 250 g / L calcium hydroxide aqueous solution was added to the reaction vessel, and after stirring for 1 hour, the mixture was filtered to remove the gypsum produced by neutralization, and then the pH was adjusted with aqueous sodium hydroxide solution to obtain a liquid of lignin derivative compound (5) containing a copolymer of weight average molecular weight 114,000. The weight ratio of the structural units (I) / (II) contained in the obtained lignin derivative compound (5) was 40 / 60, and the reaction rate of the aromatic water-soluble compound was 82%. The peak area ratio of the high molecular weight component of the obtained lignin derivative compound (5) was 97%.

[0093] (3) Evaluation of asphalt additives (3-1) Preparation of asphalt samples Using a dryer, 115 ° C. × 2 hours, dried lignin derivative compounds (1), (2), (4), kraft lignin (manufactured by Domtar), and lignin sulfonate a-1 were dried at 115 ° C. × 2 hours, and then added to 60-80 straight asphalt heated to 150 ° C. in the amounts shown in Table 1. After the total amount was added, the mixture was stirred in a homomixer for 1 hour at 5000 rpm. On the other hand, the liquid lignin derivative compounds (3) and (5) were added in the amounts shown in Table 1 to 60-80 straight asphalt heated to 150 ° C., and after stirring in a homomixer to remove the moisture, the mixture was stirred for 1 hour at 5000 rpm.

[0094] (3-2) Evaluation Tests The prepared asphalt samples (Table 1) and each additive (Table 2) were subjected to the following tests.

[0095] - Viscosity - The asphalt sample after stirring at 150°C described above was transferred to an oil bath set to about 100°C and the temperature was lowered until the asphalt temperature reached about 97°C. Once the temperature stabilized, the viscosity of the asphalt sample was measured at a shear rate of 141.6 1 / s using a soft solid tester (manufactured by Brookfield) with a blade-type spindle (VT-40-20).

[0096] -DSC Measurement (Melting Point)- Measurement was carried out using a differential scanning calorimeter (DSC) (manufactured by TA Instruments) according to the following procedure: Approximately 5 mg of a sample was heated in a nitrogen atmosphere from -50°C to 200°C at a heating rate of 10°C / min, and this heating process was repeated twice, with the maximum endothermic peak temperature in the second heating process being taken as the melting point.

[0097] - TG-DTA Measurement (Thermal Decomposition Point, Thermal Weight Loss Rate) - Measurements were performed using a thermogravimetric differential thermal analyzer (TG-DTA) (manufactured by SII NanoTechnology Inc.) according to the following procedure. Approximately 10 mg of a sample was heated from 50°C to 600°C at a heating rate of 10°C / min in a nitrogen atmosphere, and the thermal decomposition point and thermal weight loss rate were measured (Table 2). Thermal decomposition point: The temperature at which the weight loss rate of the sample is at its maximum. Thermal weight loss rate: The weight loss rate of the sample up to 600°C.

[0098]

[0099]

[0100] Compared with lignin sulfonic acid (Comparative Example 2), lignin derivative compounds (1) to (5) had lower melting points and higher thermal decomposition temperatures. Therefore, it was found that they can exist in a fluid state even in materials that require high-temperature processing, such as asphalt. Because the melting points of lignin derivative compounds (1) to (5) are all lower than that of wax (Comparative Example 4), they are found to be compatible with asphalt even at low temperatures of around 100°C and contribute to viscosity reduction. The thermal weight loss rates of lignin derivative compounds (1) to (5) were 72 and 73%, respectively, demonstrating that they can achieve both good dispersibility and heat resistance.

[0101] (4) Evaluation of Asphalt Emulsion Compositions (4-1) Production of Asphalt Emulsion Compositions Asphalt emulsion compositions were produced by adding a lignin derivative compound in the amount shown in Table 1 to an asphalt emulsion containing an emulsifier (containing 10% by weight of emulsifier) ​​and thoroughly mixing at room temperature. The emulsifiers used contained hardened tallow diamine, tallow-based diamine ammonium salt, and hydrochloric acid in amounts of about 10% by weight, about 80% by weight, and about 10% by weight, respectively, relative to 100% by weight of the emulsifier.

[0102] (4-2) Preparation of MS Specimens Each asphalt emulsion composition (10% by weight) and aggregate (crushed stone and crushed sand: 90% by weight) were mixed at room temperature to prepare Marshall (hereinafter referred to as MS) specimens. The MS specimens were prepared in accordance with the Pavement Survey and Testing Methods Handbook, 2019 Edition (Japan Road Association, Public Interest Incorporated Association, published March 2019) B001, Marshall Test Stabilization Method and Simple Pavement Guidelines, 1979 Edition (Japan Road Association, Public Interest Incorporated Association, published 1979), except that the series of processes were carried out at room temperature. That is, the mixture was placed in a Marshall stability test mold and compacted 50 times on each side.

[0103] (4-3) Evaluation Tests The following evaluation tests were carried out on each test specimen.

[0104] - Density - After curing the MS specimen at room temperature for three days, the density of the mixture was calculated using the Vernier caliper method. That is, the height and diameter of the MS specimen were measured using the Vernier caliper method to calculate the volume. At the same time, the weight of the specimen was measured. From these measured values, the density of the mixture was calculated using the formula: density = weight / volume.

[0105] - Standard Marshall Stability Test - The MS specimen was placed in a mold in a high-temperature drying oven at 110 ± 5°C and cured for 24 hours. After removing it, it was immediately tamped 25 times on each side, cured at room temperature for one day, and then demolded. A standard Marshall stability test was then conducted according to the conditions described in B001 Marshall Test Stability Method in the Pavement Survey and Testing Methods Handbook, 2019 Edition (published by the Japan Road Association, a public interest incorporated association, in March 2019).

[0106]

[0107] As shown in Table 3, when a lignin derivative compound was added (Examples 9 and 10), the mixing properties of the room-temperature mixture during specimen preparation were good. Furthermore, the MS specimens containing the lignin derivative compound (Examples 9 and 10) had higher densities than the MS specimen without the lignin derivative compound (Comparative Example 5). These results suggest that an asphalt emulsion composition containing a lignin derivative compound together with an emulsifier can be prepared, and that the use of this emulsion composition can produce an asphalt composition that is easy to compact. Furthermore, Example 9 tended to have a higher standard Marshall stability than Comparative Example 5 without the lignin derivative compound. This confirms that adding a lignin derivative compound to an asphalt emulsion can improve the strength of the asphalt composition using it.

Claims

1. An additive for asphalt compositions, comprising a lignin derivative compound containing the following structural units (I) and (II): (I): a structural unit derived from a lignin-based compound (II): a structural unit derived from an aromatic water-soluble compound containing at least an aromatic water-soluble compound having an alkylene oxide chain.

2. The agent according to claim 1, wherein the aromatic water-soluble compound having an alkylene oxide chain includes an aromatic water-soluble compound having an alkylene oxide chain with an average added mole number of 25 or more of alkylene oxide.

3. The agent according to claim 1 or 2, which contains a lignin derivative compound in which the weight ratio (I) / (II) of the structural unit (I) to the structural unit (II) is 1 / 99 to 99 / 1.

4. An asphalt composition comprising asphalt and a lignin derivative compound containing the following structural units (I) and (II): (I): A structural unit derived from a lignin-based compound (II): A structural unit derived from an aromatic water-soluble compound containing at least an aromatic water-soluble compound having an alkylene oxide chain.

5. The asphalt composition according to claim 4, wherein the content of the lignin derivative compound is 0.005 to 3.0 parts by weight per 100 parts by weight of asphalt.

6. The asphalt composition according to claim 4 or 5, further comprising aggregate and used for road paving.

7. A pavement comprising the asphalt composition of claim 6.

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