Early-use asphalt emulsion composition

Abstract

The present invention aims to provide an asphalt emulsion composition that can improve workability and, as a result, exhibit high stability, strength, and durability. [Solution] The present invention provides an early-use asphalt emulsion composition containing a lignin derivative compound comprising (I) a structural unit derived from a lignin-based compound and (II) a structural unit derived from an aromatic water-soluble compound having an alkylene oxide chain, and an asphalt composition comprising the early-use asphalt emulsion composition and aggregate.

Description

Technical Field

[0001] The present invention relates to an early-use asphalt emulsion composition.

Background Art

[0002] As road paving materials, generally, a heated asphalt mixture obtained by mixing aggregate and asphalt in a heated state of about 200°C is used. On the other hand, as a road paving material that does not require heating, there is also a normal-temperature asphalt emulsion mixture obtained by mixing an asphalt emulsion with aggregate. The normal-temperature asphalt emulsion mixture was widely used until around the 1980s. However, with the increase in combined material plants capable of mixing heated asphalt, the high performance of road paving materials has been demanded, and the demand for asphalt emulsion mixtures with inferior strength has been decreasing.

[0003] Patent Document 1 describes that by adding water to a normal-temperature asphalt mixture containing a surfactant containing oleic acid, a predetermined amount of an alkaline additive, in addition to aggregate and asphalt, high adhesiveness, Marshall stability, and dynamic stability can be exhibited even when the road surface is wet.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the normal-temperature asphalt mixture described in Patent Document 1 has a problem that it cannot sufficiently increase the strength of the asphalt composition when aggregate is added.

[0006] An object of the present invention is to provide an asphalt emulsion composition that can improve workability and, as a result, exhibit high stability, strength, and durability. [Means for solving the problem]

[0007] The present invention provides the following [1] to [8]. [1] An early-use asphalt emulsion composition containing a lignin derivative compound comprising the following constituent units (I) and (II). (I): Constituent units derived from lignin compounds (II): Constituent units derived from aromatic water-soluble compounds, including at least one aromatic water-soluble compound having an alkylene oxide chain. [2] The early-use asphalt emulsion composition according to [1], wherein the lignin derivative compound comprises at least an aromatic water-soluble compound having an alkylene oxide chain with an average number of added alkylene oxide moles of 25 or more. [3] The early-use asphalt emulsion composition according to [1] or [2], comprising a lignin derivative compound having a weight ratio (I) / (II) of the constituent unit (I) to the constituent unit (II) of 1 / 99 to 99 / 1. [4] The early-use asphalt emulsion composition according to any one of [1] to [3], wherein the content of the lignin derivative compound is 0.01 parts by weight or more per 100 parts by weight of the composition. An asphalt composition comprising an early-use asphalt emulsion composition described in any one of items [5], [1], to [4], and aggregate. [6] The asphalt composition according to [5], which is a room-temperature asphalt composition. A method for producing an asphalt composition, comprising mixing an early-use asphalt emulsion composition described in any one of items [7], [1], to [4] with a material containing aggregate and solidifying it at room temperature. A pavement comprising the asphalt composition described in [8], [5], or [6]. [Effects of the Invention]

[0008] The asphalt emulsion of the present invention can be easily compacted when mixed with aggregate, thereby improving workability and resulting in high stability, strength, and durability. Furthermore, by applying external energy through compaction using a tandem roller or a tire roller (with vibration), water evaporation and emulsion decomposition can be promoted, accelerating the strength development of the mixture. This enables early reopening of roads when used for pavement. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows the measurement results of the change in water content during curing at room temperature in the example. [Modes for carrying out the invention]

[0010] [1. Asphalt emulsion composition] The asphalt emulsion composition contains the following lignin derivative compounds as active ingredients. This allows the composition to be easily compacted when mixed with aggregate, thereby improving workability. As a result, it exhibits high stability, strength, and durability when mixed with aggregate, further improving workability.

[0011] [1.1 Constituent Units of Lignin Derivative Compounds] Lignin derivative compounds are polymers containing at least two constituent units (I) and (II). Because lignin, the main backbone of constituent unit (I), has a very complex molecular structure, it is difficult to uniformly specify the chemical structure of lignin derivative compounds using general formulas or similar methods.

[0012] -Constituent Unit (I)- The constituent unit (I) is a constituent unit derived from a ligninsulfonic acid compound. Lignin sulfonic acid compounds are compounds that have a skeleton in which the carbon atom at the α-position of the side chain of the hydroxyphenylpropane structure of lignin is cleaved and a sulfo group (sulfonic acid group) is introduced. The structure of the above skeleton is shown in the following formula. [ka]

[0013] The lignin sulfonic acid-based compound may be a modified product of the compound having the skeleton represented by the above formula (1) (hereinafter, also referred to as "modified lignin sulfonic acid-based compound"). The modification method is not particularly limited, but chemical modification methods such as hydrolysis, alkylation, alkoxylation, sulfonation, sulfonic acid esterification, sulfomethylation, aminomethylation, desulfonation, etc.; methods of molecular weight fractionation of lignin sulfonic acid-based compounds by ultrafiltration are exemplified. Among these, as the chemical modification method, one or more modification methods selected from hydrolysis, alkoxylation, desulfonation, and alkylation are preferable.

[0014] The lignin sulfonic acid-based compound can take 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, calcium-sodium mixed salts, etc. are preferable.

[0015] The lignin sulfonic acid-based compound usually has at least one functional group site that can react with the aromatic water-soluble compound constituting the structural unit (II). Examples of such sites include carboxyl groups, hydroxyl groups (phenolic hydroxyl groups, alcoholic hydroxyl groups), thiol groups, sulfo groups, aromatic rings, ether bonds, and alkyl chains. In one aspect, the lignin derivative compound is formed by the bonding of the functional group site of the lignin sulfonic acid-based compound and the aromatic water-soluble compound directly or through a condensing agent such as formaldehyde.

[0016] The production method and origin of the lignin sulfonic acid-based compound are not particularly limited, and either natural products or synthetic products may be used. The lignin sulfonic acid-based compound is one of the main components of the waste liquid of sulfite pulp obtained by digesting wood under acidic conditions. Therefore, a lignin sulfonic acid-based compound derived from sulfite pulp waste liquid may be used.

[0017] -Structural unit (II)- The structural unit (II) is a structural unit derived from an aromatic water-soluble compound. An aromatic water-soluble compound means a compound containing at least one aromatic skeleton and exhibiting water solubility. The aromatic water-soluble compound is preferably a compound that can be bonded to a functional group contained in a lignin sulfonic acid compound by a chemical reaction, and more preferably a compound that can react with a functional group contained in a lignin sulfonic acid compound as the main component of sulfite pulp waste liquor. The form of the chemical reaction is not particularly limited, and examples include radical reactions, ionic bonds, coordination bonds, condensation reactions, reactions involving hydrolysis, reactions involving dehydration, reactions involving oxidation, reactions involving reduction, and reactions involving neutralization.

[0018] The aromatic water-soluble compound preferably has an alkylene oxide chain or a polar group. Thereby, the reactivity when forming the bond between the structural units (I) and (II) can be improved. The polar group may be an ionic functional group, and examples thereof include a carboxyl group, a hydroxyl group, a sulfo group, a nitroxyl group, a carbonyl group, a phosphate group, an amino group, and an epoxy group. Anionic functional groups such as a hydroxyl group, a carboxyl group, a sulfo group, and a phosphate group are preferred, and a carboxyl group and a sulfo group are more preferred. The anionic functional group in the lignin derivative compound can be quantitatively and qualitatively observed by instrumental analysis such as NMR and 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 unit constituting the alkylene oxide chain (group) is not particularly limited, and is usually 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 added moles of alkylene oxide units is usually 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 emulsion 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 emulsion composition. Therefore, the average number of added moles is preferably 20 to 300, or 25 to 300, more preferably 30 to 200, and even more preferably 35 to 150. The average number of moles added mentioned above is a guideline, and regardless of whether or not it meets the above range, the alkylene oxide chain may include units that do not have repeated alkylene oxide units (monoalkylene oxide groups).

[0021] A polyalkylene oxide chain may consist of one or more alkylene oxide groups. The addition of each alkylene oxide group to a polyalkylene oxide chain composed of two or more alkylene oxide groups may be random, block, or a mixture thereof. The terminal units of a polyalkylene oxide chain are usually hydroxyl groups, but are not limited to these; they may be alkyl ethers or carboxylic acid esters, provided they do not interfere with bonding with ligninsulfonic acid compounds.

[0022] Examples of aromatic water-soluble compounds having alkylene oxide chains 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 co-condense well, at least one of polyalkylene oxide alkylphenyl ethers and polyalkylene oxide phenyl ethers is more preferred, and polyalkylene oxide phenyl ethers (especially oxyalkylene group adducts to phenol) (for example, poly(ethylene oxide) monophenyl ether, poly(propylene oxide) monophenyl ether, the preferred range for the average number of added moles of ethylene oxide units and propylene oxide units is as described above) is even more preferred. The aromatic water-soluble compound having an alkylene oxide chain may be one type or a combination of two or more types.

[0023] (Aromatic water-soluble compounds containing 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 specifically, examples include isophthalic acid, oxynaphthoic acid, benzoic acid, hydroxybenzoic acid, and their isomers. 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 compounds containing a sulfo group) Examples of aromatic water-soluble compounds having a sulfo group include alkylnaphthalene sulfonic acid, alkylphenol sulfonic acid, aniline sulfonic acid, and alkylbenzene sulfonic acid. More specifically, examples include naphthalene sulfonic acid, methylnaphthalene sulfonic acid, butylnaphthalene sulfonic acid, phenol sulfonic acid, cresol sulfonic acid, aniline sulfonic acid, benzene sulfonic acid, toluene sulfonic acid, their isomers, and condensates. An example of a condensate is naphthalene sulfonic acid formaldehyde condensate. Due to their good reactivity, phenol derivatives and aniline sulfonic acid having a sulfo group are preferred, phenol sulfonic 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) Other aromatic water-soluble compounds include aromatic water-soluble compounds that do not have alkylene oxide chains, carboxyl groups, or sulfo groups, such as (alkyl)phenols like phenol and cresol. These other aromatic water-soluble compounds may be one type or a combination of two or more types.

[0026] The aromatic water-soluble compound includes at least an aromatic water-soluble compound having an alkylene oxide chain, and more preferably is the aromatic water-soluble compound having an alkylene oxide chain alone, or a combination of said compound and an aromatic water-soluble compound having a carboxyl group and / or an aromatic water-soluble compound having a sulfo group.

[0027] The constituent unit (II) may be a constituent unit derived from one aromatic water-soluble compound, or from two or more aromatic water-soluble compounds. The aromatic water-soluble compound may be a single compound, or a combination of two or more, preferably only an aromatic water-soluble compound having an alkylene oxide chain, or a combination of said compound and an aromatic water-soluble compound having a carboxyl group and / or an aromatic water-soluble compound having a sulfo group.

[0028] -Other constituent units (III)- Lignin derivative compounds may have a constituent unit (III) other than constituent units (I) and (II). Examples include aromatic compounds other than aromatic water-soluble compounds (e.g., simple aromatic hydrocarbon compounds such as benzene and naphthalene), (poly)alkylene glycol alkenyl ether compounds; and constituent units derived from water-soluble polyalkylene glycols, polyoxyalkylene compounds, polycarboxylic acid compounds, and polyester compounds, each having hydrogen atoms at both ends (e.g., polymer blocks described in International Publication No. 2018 / 56124). Constituent unit (III) may be one type or a combination of two or more types.

[0029] [1.2 Composition ratio of each constituent unit of lignin derivative compounds] The weight ratio (I) / (II) of constituent unit (I) to constituent 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, even more preferably 15 / 85 to 70 / 30, or 20 / 80 to 60 / 40 (assuming the sum of (I) and (II) is 100% by weight).

[0030] When component unit (III) is included, its weight ratio is usually 5% by weight or less, preferably 3% by weight or less, and more preferably 2% by weight or less, relative to the total of 100% by weight of (I) and (II).

[0031] (I) / (II) is defined as (weight of solids of the ligninsulfonic acid compound before reaction) / (weight of solids of the aromatic water-soluble compound before reaction) in the reaction between a ligninsulfonic acid compound and an aromatic water-soluble compound, and this method is also used for measurement in the examples described later.

[0032] If the constituent unit (II) includes constituent units derived from compounds other than aromatic water-soluble compounds having alkylene oxide chains, the ratio of constituent units derived from aromatic water-soluble compounds having alkylene oxide chains to constituent 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, and it is acceptable as long as it is 100% by weight or less.

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

[0034] [1.3 Salts of lignin derivative compounds] The lignin derivative compound can be any reaction product obtained by the above-described reaction, and may be either a free acid or its neutralized salt. Neutralized salts are preferred because they facilitate the storage and use of the polymer. Examples of neutralized salts of the reaction product include alkali metal salts such as sodium 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 Compounds] 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 this invention can be measured by a known method of converting it to polyethylene glycol using gel permeation chromatography (GPC).

[0037] The following conditions are examples of GPC measurement conditions. The measurements in the later examples were also taken under these conditions. Measuring device; manufactured by Tosoh Corporation. Columns used: Shodex Column OH-pak SB-806HQ, SB-804HQ, SB-802.5HQ Eluent: 0.05 mM sodium nitrate / acetonitrile 8 / 2 (v / v) Standard material: Polyethylene glycol (manufactured by Tosoh or GL Science) Detector; Differential refractometer (manufactured by Tosoh Corporation)

[0038] [1.5 Method for producing lignin derivative compounds] The preparation of lignin derivative compounds can be carried out by reacting a starting compound containing a ligninsulfonic acid compound (hereinafter sometimes referred to as compound (i)) and an aromatic water-soluble compound (hereinafter sometimes referred to as compound (ii)). For example, a method of reacting a ligninsulfonic acid compound with an aromatic water-soluble compound can be used. More specifically, methods include condensation (e.g., formaldehyde condensation), radical reaction, and ionic bonding of a ligninsulfonic acid compound with an aromatic water-soluble compound. As an example of a formaldehyde condensation method, formaldehyde is added to the ligninsulfonic acid compound and bonded to the aromatic water-soluble compound. As an example of a radical reaction method, a hydrogen radical is abstracted from the ligninsulfonic acid compound by acting a radical initiator on it, and the generated radical is subjected to a radical reaction with at least one aromatic water-soluble compound.

[0039] The method for producing lignin sulfonic acid compounds as raw materials is not particularly limited; for example, they can be produced by extraction from the wastewater of sulfurous acid pulp obtained by pulping wood under acidic conditions. Furthermore, powdered products that have undergone drying treatments such as powder drying may also be used. Being in powder form makes handling easier.

[0040] The lignin sulfonic acid compound may be a commercially available product, such as Vanirex HW (manufactured by Nippon Paper Industries Co., Ltd.), Sunex M (manufactured by Nippon Paper Industries Co., Ltd.), Pearllex NP (manufactured by Nippon Paper Industries Co., Ltd.), or Sunflow RH (manufactured by Nippon Paper Industries Co., Ltd.). The lignin sulfonic acid compound may also be in the form of a salt such as a monovalent metal salt, divalent metal salt, ammonium salt, or organic ammonium salt (preferably a monovalent metal salt, divalent metal salt, more preferably a calcium salt, magnesium salt, sodium salt, or calcium-sodium mixed salt).

[0041] The reaction temperature between ligninsulfonic acid compounds and aromatic compounds can 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. Furthermore, when using a low-boiling point compound as the reaction solvent, it is preferable to carry out the reaction under pressure using an autoclave in order to improve the reaction rate.

[0042] The reaction between the lignin sulfonic acid compound and the aromatic water-soluble compound may be carried out in either a solution reaction or a bulk reaction. In the case of a solution reaction, a solvent may be used. Examples of solvents 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. Of these, at least one of water and a lower alcohol is preferred, with water being more preferred. This improves the solubility of the starting monomers and the resulting copolymer, and eliminates the need for a desolvation step. The solvent may be used alone or in combination of two or more (for example, a water-alcohol mixed solvent).

[0043] An antifoaming agent may be used during the preparation of lignin derivatives. This can suppress foaming during the reaction and allow for the construction of a homogeneous reaction system. Examples of antifoaming agents include those containing nonionic surfactants as active ingredients.

[0044] The reaction progresses by a clear increase in viscosity. Once the desired viscosity is reached, the reaction can be stopped by cooling or neutralization.

[0045] In the preparation of lignin derivative compounds, water may be added to control the condensation viscosity and condensation time. The pH during the reaction may also be adjusted to an appropriate value. The reaction is usually carried out under acidic conditions. If the reaction system is already acidic due to the sulfo group-containing aromatic compound and any unreacted acid contained therein, the reaction can be carried out in the acidic region. If the reaction system is not acidic, an acid catalyst such as hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, or p-toluenesulfonic acid may be added beforehand. Sulfuric acid is preferred, but other acids are also acceptable and not limited to those specified above.

[0046] The reaction rate of the aromatic water-soluble 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 allows the resulting lignin derivative to effectively improve the stability of the asphalt emulsion composition.

[0047] The reaction rate of aromatic water-soluble compounds can be measured as follows, and this method is also used in the examples described later. First, the peak areas before and after the reaction are compared when UV (detection wavelength 280 nm) is used in the GPC measurement. Next, if the peak area before the reaction (i.e., the peak area of ​​the peak corresponding to the aromatic water-soluble 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 the weight-average molecular weight measurement described above.

[0048] If necessary, the reaction solution after the condensation reaction may be subjected to post-treatment such as heat treatment at a temperature of 60 to 120°C under a pH of 8.0 to 13.0, neutralization treatment, or adjustment of the pH of the reaction solution (for example, lowering it to 1.0 to 4.0, preferably 1.5 to 2.0) to precipitate the reaction product as a solid. Post-treatment is usually carried out continuously for about 10 minutes to 3 hours. This can significantly reduce 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 described above, other methods for reducing excess formaldehyde, known in the field of chemistry for melamine-formaldehyde resins and phenol-formaldehyde resins, may be used. Such methods include, for example, the addition of a formaldehyde absorbent (addition of a small amount of sodium bisulfite, addition of hydrogen peroxide).

[0049] In the process of adjusting the pH of the reaction solution to precipitate the reaction product as a solid, the supernatant salt solution is then separated and removed. The remaining free reaction product, which is mostly salt-free, can then be dissolved again in an amount of water sufficient to obtain the desired solid concentration to acquire the lignin derivative.

[0050] The neutralization treatment can be carried out using a neutralizing agent capable of neutralizing the reaction products and catalyst. Examples of neutralizing agents include basic compounds such as sodium hydroxide, calcium hydroxide, and Ba(OH)2 (including their salts and hydroxides). This causes less soluble calcium sulfate and barium sulfate to form together with free sulfuric acid, which precipitate in the form of gypsum or similar. Therefore, the precipitate can be separated and removed by subsequent filtration, and a salt-free polymer can be obtained. Furthermore, undesirable sodium sulfate may be separated and removed by dialysis or ultrafiltration.

[0051] When by-products such as sodium sulfate, calcium sulfate, or their hydrates are generated during the addition and neutralization of basic compounds, it is preferable to add the basic compound while the mixture is still warm after the reaction and maintain the warming state to improve the removal of these by-products. Warming to 40°C or higher is preferable. The warming state should be maintained for 30 minutes or more. After the reaction is complete, the resulting lignin derivative compound may be adjusted in concentration, pH, etc., as needed.

[0052] [1.6 Content of lignin derivative compounds] The content of the lignin derivative compound in the asphalt emulsion composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and even more preferably 0.1% by mass or more, based on the total mass of the composition. There is no particular upper limit, for example, 30% by mass or less, 20% by mass or less, or 10% by mass or less.

[0053] [1.7 Other ingredients] The asphalt emulsion composition further contains other components besides the lignin derivative compound, such as asphalt and emulsifiers.

[0054] -asphalt- Examples of asphalt (bituminous material) include straight asphalt and modified asphalt (polymer-modified asphalt, semi-blown asphalt, hard asphalt), and any of these may be used.

[0055] The asphalt content is preferably 30 to 65% by mass, more preferably 35 to 65% by mass, and even more preferably 40 to 65% by mass, relative to the total mass of the asphalt emulsion.

[0056] -emulsifier- Any type of emulsifier can be used in the asphalt emulsion: cationic, anionic, nonionic, or amphoteric. Among these, cationic emulsifiers are preferred from the viewpoint of better demonstrating the effects of the present invention.

[0057] Examples of cationic emulsifiers include primary amines, secondary amines, tertiary amines, quaternary ammonium salts, and polyamines. Specifically, examples include alkyl(poly)amines (e.g., alkylmonoamines, alkyldiamines, alkyltriamines), amideamines, alkylpolyamines, alkylimidazolines, hydroxyalkylamines, rosinamines, and other amines, as well as their salts (e.g., mineral salts (e.g., hydrochloride salts), lower carboxylate salts, sulfamate salts, quaternary ammonium salts). Alkylamines or their salts are preferred as cationic emulsifiers, and (hydrogenated) beef tallow diamines or their salts (e.g., hydrochloride salts) are more preferred.

[0058] Examples of anionic emulsifiers include fatty acids, alkyl sulfates, alkyl ether sulfates, alkylbenzene sulfonic acid, naphthalene sulfonic acid, alkylnaphthalene sulfonic acid, melamine sulfonic acid, rosin acid, alkyl phosphoric acid, and salts thereof.

[0059] 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.

[0060] Examples of amphoteric emulsifiers include betaine-type emulsifiers such as betaine acetate, amide betaine, sulfobetaine, and imidazolium betaine, as well as amination lignin and amine oxide.

[0061] The emulsifier content (or the total amount of acid and emulsifier if the acid described later is further included) is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, and even more preferably 1 to 10% by mass, relative to the total mass of the asphalt emulsion. When the emulsifier content is within the above range, aggregation of the asphalt emulsion can be suppressed and the miscibility with aggregate can be further improved.

[0062] -acid- The asphalt emulsion composition may contain an acid, and if it contains a cationic emulsifier, it is preferable to further contain an acid. This allows the pH of the composition to be adjusted and improves its performance as an emulsion. Examples of acids include hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid, acetic acid, and glycolic acid, with hydrochloric acid and phosphoric acid being preferred, and hydrochloric acid being more preferred.

[0063] -solvent- Asphalt emulsion compositions typically exhibit a state in which asphalt is dispersed in a solvent (dispersion), and preferably, they can maintain this dispersion state at room temperature. Examples of solvents include water and organic solvents. Examples of organic solvents include alcohols such as methanol, ethanol, isopropanol, and alkylene glycol; ketones such as acetone and methyl ethyl ketone; esters / ethers / amides of alkylene glycols; and combinations of two or more selected from these. Water, or a combination of water and an organic solvent, is preferred.

[0064] -Optional ingredients- The asphalt emulsion composition may further contain optional components other than lignin derivative compounds, asphalt, and emulsifiers. Examples of optional components include anticoagulants, fluidizers, plasticizers, electrolytes, anti-adhesion agents, and two or more combinations selected from these.

[0065] [1.8 Method for producing asphalt emulsion composition] The asphalt emulsion composition can be manufactured by mixing raw materials containing a lignin derivative compound (asphalt, emulsifier, etc.) either all at once or sequentially. While there are no particular limitations on the order of sequential mixing, it is preferable to mix the emulsifier and lignin derivative and then add this mixture to separately mixed asphalt. Stirring may be performed during mixing as needed. The mixing temperature is not particularly limited but may be adjusted depending on the type of raw materials being mixed. For example, the mixing temperature for asphalt is 150-185°C, the mixing temperature when the emulsifier (containing the lignin derivative compound) is added is 40-70°C, and the mixing temperature after adding the lignin derivative compound during asphalt emulsion production is room temperature (e.g., 5-80°C), preferably 15-50°C.

[0066] [1.9 Characteristics and Uses of Asphalt Emulsion] The asphalt emulsion composition of the present invention can be used immediately after preparation and can be used as an early-use asphalt emulsion composition.

[0067] Asphalt emulsion compositions can be used for surface treatment of each layer in asphalt pavement (improvement of properties such as adhesion and waterproofing). Asphalt emulsions are generally classified according to their use, such as for penetration and mixing. For example, the following classifications are made: Classification in JIS K 2008 (2000): No. 3 PK-3 (for prime coat and cement-stabilized layer curing); Cationic emulsion for mixing No. 1 MK-1 (for mixing with coarse-graded aggregate), No. 2 MK-2 (for mixing with dense-graded aggregate); Nonionic emulsion for mixing No. 1 MN-1 (for cement-asphalt emulsion stabilization mixing); Classification according to JEAAS-2006: High-penetration asphalt emulsion PK-P (for prime coat), high-concentration asphalt emulsion PK-H (for penetration and surface treatment), modified asphalt emulsion MS-1 (for microsurfacing). The asphalt emulsion composition of the present invention can be used for any of these purposes.

[0068] [2. Asphalt Composition] The asphalt composition (asphalt mixture, asphalt composite) includes the above-mentioned asphalt emulsion composition.

[0069] [2.1 Content of asphalt emulsion composition] In an asphalt composition (assuming 100% by weight), the effective amount of the asphalt emulsion composition is typically 0.0001% by weight or more, preferably 0.01% by weight or more, and more preferably 0.05% by weight or more, when converted to the amount of the lignin derivative compound. The amount of the asphalt emulsion composition is typically 1% by weight or more, preferably 3% by weight or more, and more preferably 5% by weight or more. The upper limit is typically 30% by weight or less, preferably 20% by weight or less, and more preferably 15% by weight or less.

[0070] [2.2 Other ingredients] The asphalt composition contains other components such as aggregates in addition to the asphalt emulsion composition. The asphalt is the same as the asphalt that may be included in the asphalt emulsion composition.

[0071] -aggregate- Examples of aggregates include crushed stone, crushed rock, boulders, gravel, sand, crusher run, recycled aggregate, and ceramics. The aggregate usually includes a combination of fine aggregate and coarse aggregate. 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, which have relatively small particle sizes (e.g., aggregate with particle sizes between 0.075 mm and 2.36 mm). Examples of coarse aggregate include crushed stone and other aggregates with relatively large particle sizes (e.g., aggregate with particle sizes greater than 2.36 mm). The aggregate may also be recycled asphalt aggregate (e.g., crushed and decomposed asphalt from used asphalt). The aggregate may further contain fillers (aggregates smaller than the fine aggregate, e.g., aggregate with particle sizes less than 0.075 mm). The aggregate particle size can be measured according to the definition of particle size in JIS A5001:1995. The weight ratio of fine aggregate, coarse aggregate, and filler is not particularly limited.

[0072] The amount of aggregate in the asphalt composition (assuming 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. Within this range, the durability of the pavement layer can be improved.

[0073] - Components other than asphalt and aggregate - The asphalt composition may contain components other than aggregate. Examples include fillers (e.g., stone powder), emulsifiers, solvents (e.g., water), pigments, and synthetic rubber.

[0074] [2.3 Method for producing asphalt composition] Asphalt compositions can be manufactured by adding each of the constituent raw materials (asphalt emulsion composition, aggregate, and any other components used as needed) all at once or sequentially and mixing them. Mixing is preferably carried out at room temperature (for example, 5 to 80°C).

[0075] [2.4 Pavement] The above asphalt composition can be used to form a pavement. A pavement usually has a layered structure including a base layer, a subgrade, and a surface layer, in that order from bottom to top. Layers containing the asphalt emulsion composition may be formed on the surface of the surface layer, between the surface layer and the subgrade, and / or between the subgrade and the base layer. As a method for manufacturing a pavement layer, for example, a method in which a subgrade is formed on the surface of the base layer and a surface layer is formed on the surface of the subgrade is given as follows. First, a base layer is formed by laying crushed stone, gravel, etc. on a subgrade formed by excavating the road surface and laying sand, etc. The base layer may be formed in two layers. For example, a method can be given in which a lower base layer is formed by laying and leveling large crushed stone, and then an upper base layer is formed by laying and leveling relatively small crushed stone. When forming the base layer, compaction may be performed using equipment such as a compaction vehicle as needed. Subsequently, a subgrade is formed on the base layer. Formation of the base layer can be done, for example, by spreading a heated asphalt composition on the roadbed and compacting it using equipment such as a compaction vehicle as needed. Subsequently, the surface layer is formed on the base layer. Formation of the surface layer can be done, for example, by spreading a heated asphalt composition on the base layer and compacting it using equipment such as a compaction vehicle as needed. Construction can usually be carried out at room temperature. When forming layers containing an asphalt emulsion composition (e.g., tack coat, prime coat), for example, after forming the roadbed, base layer, or surface layer, the asphalt emulsion composition can be sprayed onto the layer surface, cured with aggregate such as sand as needed, and then the upper layers can be constructed sequentially. [Examples]

[0076] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0077] Examples 1-3 and Comparative Example 1: Production of Asphalt Composition The following procedure was used to prepare an asphalt emulsion containing a lignin derivative compound, and an asphalt composition containing the same, and to evaluate their performance.

[0078] (1) Production of lignin derivative compounds The following lignin derivative compounds -1 to -4 were used, respectively.

[0079] (1) Preparation of lignin sulfonate (powder) (1-1) Adjustment of lignin sulfonate-1 Wood derived from radiata pine was treated with a magnesium sulfite solution with an SO2 concentration of 4 g / 100 mL at 140°C and pH 2 for 3 hours using the sulfite pulping method. The resulting composition was filtered, and the filtrate was adjusted to pH 5.0 with an aqueous sodium hydroxide solution. The filtrate was then spray-dried using a spray dryer to obtain lignin sulfonate-1 powder.

[0080] (1-2) Adjustment of Lignin Sulfonate-2 Wood derived from radiata pine was treated with a magnesium sulfite solution with an SO2 concentration of 4 g / 100 mL at 140°C and pH 2 for 3 hours using the sulfite pulping method. To the resulting composition, a magnesium hydroxide solution was added to a solid content of 9 wt%, and the mixture was held at 90°C for 4 hours. Subsequently, oxygen was blown in for 2 hours for oxygen treatment, the pH was adjusted to 7.0, and the mixture was spray-dried using a spray dryer to obtain lignin sulfonate-2 powder.

[0081] (1-3) Preparation of lignin sulfonate-3 Wood derived from radiata pine was treated with a magnesium sulfite solution with an SO2 concentration of 4 g / 100 mL at 140°C and pH 2 for 3 hours using the sulfite pulping method. The resulting composition was filtered, and the filtrate was adjusted to pH 5.0 with an aqueous sodium hydroxide solution. The filtrate was concentrated using a polysulfone-based ultrafiltration membrane with a molecular weight cutoff of 20,000, and spray-dried using a spray dryer to obtain lignin sulfonate-3 powder.

[0082] (2) Preparation of lignin derivatives (2-1) Preparation of lignin derivative-1 In a glass reaction vessel equipped with a thermometer, stirrer, reflux apparatus, and dropper, 212 g of water, 90 g of lignin sulfonate-1 as compound (i), 124 g of poly(ethylene oxide) monophenyl ether (average number of moles of ethylene oxide added: 50) as compound (ii), 17 g of 37% formaldehyde aqueous solution, 74 g of 72% sulfuric acid aqueous solution, and 0.05 g of Pronal 753 (manufactured by Toho Chemical Co., Ltd.) as an antifoaming agent were added. The mixture was stirred while heating and held at 105°C for 3 hours to complete the reaction. To the resulting aqueous solution, 140 g of 250 g / L calcium hydroxide aqueous solution was added to the reaction vessel and stirred for 1 hour. After filtering the mixture to remove the gypsum produced by neutralization, the pH was adjusted with sodium hydroxide aqueous solution to obtain a liquid lignin derivative-1 containing a copolymer with a weight-average molecular weight of 47,600.

[0083] This liquid was dried at 140°C using a drum dryer (manufactured by Katsuragi Industries Co., Ltd.), and then pulverized with an extreme mill to obtain a dried product of lignin derivative compound-1.

[0084] The weight ratio of each constituent unit in the obtained lignin derivative compound-1 was (I) / (II) = 42 / 58, and the reaction rate was 77%.

[0085] (2-2) Preparation of lignin derivative-2 In a glass reaction vessel equipped with a thermometer, stirrer, reflux apparatus, and dropper, 150 g of water, 92 g of poly(ethylene oxide) monophenyl ether (average number of moles of ethylene oxide added: 50) as compound (ii), 60 g of lignin sulfonate-2 as compound (i), 12 g of 37% formaldehyde aqueous solution, and 49 g of 72% sulfuric acid aqueous solution were added. The mixture was stirred while heating and maintained at 105°C for 6 hours to complete the reaction. To the resulting aqueous solution, 106 g of 250 g / L calcium hydroxide aqueous solution was added to the reaction vessel and stirred for 1 hour. After filtering the mixture to remove the gypsum produced by neutralization, the pH was adjusted with sodium hydroxide aqueous solution to obtain a liquid lignin derivative compound-2 containing a copolymer with a weight-average molecular weight of 29,000.

[0086] This liquid was dried at 140°C using a drum dryer (manufactured by Katsuragi Industries Co., Ltd.), and then pulverized with an extreme mill to obtain a dried product of lignin derivative compound-2.

[0087] The weight ratio of each constituent unit in the obtained lignin derivative compound-2 was (I) / (II) = 28 / 72, and the reaction rate of compound (i) with compound (ii) was 84%.

[0088] (2-3) Preparation of lignin derivative-3 In a glass reaction vessel equipped with a thermometer, stirrer, reflux apparatus, and dropper, 305 g of water, 25 g of lignin sulfonate-3 as compound (i), 37 g of poly(ethylene oxide) monophenyl ether (average number of moles of ethylene oxide added: 47 moles) as compound (ii), 6 g of 37% formaldehyde aqueous solution, 22 g of 72% sulfuric acid aqueous solution, and 0.02 g of Pronal 753 (manufactured by Toho Chemical Co., Ltd.) as an antifoaming agent were added. The mixture was stirred while heating and maintained at 105°C for 16 hours to complete the reaction. To the resulting aqueous solution, 45 g of 250 g / L calcium hydroxide aqueous solution was added to the reaction vessel and stirred for 1 hour. After filtering the mixture to remove the gypsum produced by neutralization, the pH was adjusted with sodium hydroxide aqueous solution to obtain a liquid lignin derivative-3 containing a copolymer with a weight-average molecular weight of 114,000.

[0089] The weight ratio of each constituent unit in the obtained lignin derivative compound-3 was (I) / (II) = 40 / 60, and the reaction rate between compound (i) and compound (ii) was 82%.

[0090] (2-4) Preparation of lignin derivative-4 In a glass reaction vessel equipped with a thermometer, stirrer, reflux apparatus, and dropper, 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 37% formaldehyde aqueous solution, and 61 g of 72% sulfuric acid aqueous solution were added. The mixture was stirred while heating and maintained at 105°C for 3 hours to complete the reaction. To the resulting aqueous solution, 127 g of 250 g / L calcium hydroxide was added to the reaction vessel and stirred for 1 hour. After filtering the mixture to remove the gypsum produced by neutralization, the pH was adjusted with sodium hydroxide aqueous solution to obtain a liquid lignin derivative compound-4 containing a copolymer with a weight-average molecular weight of 29,500.

[0091] The weight ratio of each constituent unit in the obtained lignin derivative compound-3 was (I) / (II) = 50 / 50, and the reaction rate of aromatic water-soluble compound-4 was 59%.

[0092] (3) Manufacture of early-use asphalt emulsion composition An asphalt emulsion composition was prepared by adding a lignin derivative compound in the amount specified in Table 1 to an asphalt emulsion characterized by containing the emulsifiers listed in Table 1, and thoroughly mixing the mixture at room temperature.

[0093] [Table 1]

[0094] (4) Manufacturing of MS test specimens Marshall (hereinafter referred to as MS) specimens were prepared by mixing the above-mentioned asphalt emulsion composition (10% by weight) and aggregate (crushed stone and crushed sand: 90% by weight) at room temperature. The preparation of the MS specimens was carried out in accordance with the Pavement Survey and Testing Methods Handbook, 2019 Edition (Japan Road Association, published March 2019), B001 Marshall Test Stabilization Method and Simple Pavement Guidelines, 1979 Edition (Japan Road Association, published 1979). Specifically, the mixture was placed in a Marshall stability test mold and compacted 50 times on each side.

[0095] (5) Evaluation Test The following evaluation tests were performed on each specimen.

[0096] (5-1) Density of a mixture at room temperature After curing the MS specimens at room temperature for three days, the density of the mixture was calculated using the caliper method. Specifically, the height and diameter of the MS specimens were measured using calipers, and the volume was calculated. The weight of the specimens was also measured. From these measurements, the density of the mixture was calculated using the formula: density = weight / volume (Table 2).

[0097] (5-2) Cantablo test After curing the MS specimens at 20°C for 7 days, a cantablo test was conducted at 20°C according to the Cantablo test method described in the Pavement Survey and Testing Methods Handbook, FY2019 Edition (Japan Road Association, published March 2019), and the loss rate due to the change in mass of the specimens before and after the test was calculated (Table 2).

[0098] (5-3) Standard Marshall Stability Test The MS specimens were placed in a mold and then in a high-temperature drying oven at 110±5℃ for 24 hours. Immediately after removal, both sides were compacted 25 times each, and after curing at room temperature for one day, the molds were removed. Subsequently, a standard Marshall stability test was performed according to the conditions described in the Pavement Survey and Testing Methods Handbook, FY2019 Edition (Japan Road Association, published March 2019), B001 Marshall Stabilization Method (Table 2).

[0099] (5-4) Water content in the mixture The following procedure was used to calculate the change in mass over time (change in moisture content) due to water evaporation when the above MS specimen was cured at room temperature.

[0100] Specifically, the moisture content was calculated using the following formula: Moisture content % = Weight A immediately after preparation - Weight B after preparation / Final weight C × 100 (Figure 1).

[0101] The results of the above tests yielded the findings shown in Table 2 below.

[0102] [Table 2]

[0103] MS specimens with added lignin derivative compounds (Examples 1-6) had a higher density than the MS specimen without the compound (Comparative Example 1) (Figure 1). This result suggests that using an asphalt emulsion composition containing a lignin derivative compound can yield asphalt that is easily compacted even at room temperature.

[0104] MS specimens with lignin derivative compound-1 added (Examples 1-6) showed lower loss rates in the Cantablo test, higher standard Marshall stability, and better miscibility and storage stability of the room-temperature mixture compared to the MS specimen without the compound (Comparative Example 1). Furthermore, when comparing Examples 1-3, which used lignin derivative compound-1 but with varying amounts, Marshall stability increased as the amount of lignin derivative compound added increased (Examples 2 and 3) (Table 2). These results indicate that asphalt emulsion compositions containing lignin derivative compounds can improve strength and aggregate scattering resistance even when mixed with aggregates at room temperature.

[0105] MS specimens with added lignin derivative compound-1 (Examples 1-3) tended to show a slower rate of decrease in moisture content than MS specimens without the compound (Comparative Example 1), but by the third day after production, the moisture content of all specimens was 0.5% or less (Figure 1). This result indicates that the inclusion of the lignin derivative compound in the asphalt emulsion composition allows for a high water retention rate immediately after production, making compaction easier and improving workability and constructability. Furthermore, it also indicates that applying external energy during compaction using tandem rollers or tire rollers (with vibration) promotes water evaporation and emulsion decomposition, accelerating the strength development of the mixture and enabling earlier reopening of the road to traffic.

Claims

1. An early-use asphalt emulsion composition containing a lignin derivative compound comprising the following constituent units (I) and (II). (I): Constituent unit derived from lignin compounds (II): Constituent units derived from aromatic water-soluble compounds, including at least one aromatic water-soluble compound having an alkylene oxide chain.

2. The early-use asphalt emulsion composition according to claim 1, wherein the lignin derivative compound comprises at least an aromatic water-soluble compound having an alkylene oxide chain with an average number of added alkylene oxide moles of 25 or more.

3. The early-use asphalt emulsion composition according to claim 1 or 2, comprising a lignin derivative compound having a weight ratio (I) / (II) of the constituent unit (I) to the constituent unit (II) of 1 / 99 to 99 / 1.

4. The early-use asphalt emulsion composition according to claim 1 or 2, wherein the content of the lignin derivative compound is 0.01 parts by weight or more per 100 parts by weight of the composition.

5. An asphalt composition comprising the early-use asphalt emulsion composition and aggregate according to claim 1 or 2.

6. The asphalt composition according to claim 5, which is a room-temperature asphalt composition.

7. A method for producing an asphalt composition, comprising mixing the early-use asphalt emulsion composition described in claim 1 or 2 with a material containing aggregate and solidifying it at room temperature.

8. A pavement comprising the asphalt composition described in claim 5.

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