JP7655643B2 - Road paving emulsion - Google Patents

Description

The present invention relates to an emulsion for road paving and its manufacturing method, as well as a composition for road paving and a paint composition for colored paving.

In recent years, due to the diversification of traffic conditions, sidewalks and bicycle paths that are clearly distinguished from roadways have been increasingly constructed. By using colored pavement for such pavements, the roadway can be clearly distinguished from the bicycle path or sidewalk by coloring. Colored pavements are mainly made using water dispersions of acrylic resins and polyester resins.
Patent Document 1 discloses a road paving composition that can be applied at room temperature, develops sufficient strength soon after application, and enables efficient formation or repair of pavements. The road paving composition contains an aqueous dispersion in which a resin (A) having a specific acid value is neutralized with a basic compound, and a silane coupling agent having an alkoxy group having 1 to 5 carbon atoms and an amino group, and serves as a binder for aggregates in road paving or a surface layer of a pavement.
Polyamide resins are also known as resins that are expected to bond strongly to aggregates and improve the water resistance of coating films.
Patent Document 2 discloses an aqueous dispersion that is substantially free of emulsifiers or surfactants and can provide a polyamide resin coating film having good adhesion, flexibility, chemical resistance, and heat-resistant adhesion, the aqueous dispersion having excellent dispersion stability even at room temperature and a small particle size sufficient to form a dense coating film, the aqueous dispersion containing a specific amount of dimer acid as a dicarboxylic acid component and a dimer acid-based polyamide resin having a specific acid value and a specific number average particle size dispersed in an aqueous medium, the aqueous dispersion containing a specific basic compound and substantially free of a specific aqueous dispersing aid.

JP 2005-126998 A JP 2011-094072 A

In the technique described in Patent Document 1, the water resistance and durability of the coating film of the pavement may be insufficient.
In addition, when using the polyamide resin described in Patent Document 2, it may be difficult to obtain an aqueous dispersion because the particles may aggregate due to the strong intermolecular interaction of the amide bond. Patent Document 2 describes that a stable emulsion can be obtained even at room temperature by performing dispersion under high pressure conditions, but since the dispersion is performed under high pressure conditions in this technology, decomposition may be easily induced and storage stability may be low, particularly at high temperatures.
The present invention relates to an emulsion for road paving that has storage stability at high temperatures.

The present invention relates to the following [1] to [4].
[1] An emulsion for road paving, comprising a polyamide (A) and at least one carboxylic acid compound (B) selected from a branched-chain aliphatic carboxylic acid having from 8 to 24 carbon atoms and a linear aliphatic carboxylic acid containing a secondary carboxy group having from 8 to 24 carbon atoms.
[2] A method for producing an emulsion for road paving, comprising the following step 1:
Step 1: A step of adding an aqueous medium to an organic solvent solution of a polyamide (A) and a carboxylic acid compound (B) to effect phase inversion emulsification [3] A road paving composition comprising the road paving emulsion described in [1] above and silica sand.
[4] A colored pavement coating composition, comprising the road pavement composition according to [3] above, further comprising a pigment.

The present invention provides an emulsion for road paving that has storage stability at high temperatures.

[Road paving emulsion]
The emulsion for road paving of the present invention contains a polyamide (A) and at least one carboxylic acid compound (B) selected from a branched-chain aliphatic carboxylic acid having from 8 to 24 carbon atoms and a linear aliphatic carboxylic acid containing a secondary carboxy group having from 8 to 24 carbon atoms.
According to the above, an emulsion for road paving having storage stability at high temperatures can be obtained. Furthermore, this technology can be applied to provide a composition for road paving and a coating composition for colored paving.
Although the detailed mechanism by which the effects of the present invention are obtained is unclear, part of it is thought to be as follows.
In the present invention, when dispersing polyamide, at least one carboxylic acid compound selected from a branched chain aliphatic carboxylic acid compound having from 8 to 24 carbon atoms and a secondary carboxy group-containing linear aliphatic carboxylic acid compound having from 8 to 24 carbon atoms is used, which has good solubility in organic solvents and good compatibility with polyamide resins, and can obtain uniform particles without separation when made into a dispersion. Furthermore, neutralization of the terminal carboxylic acid can improve the electrostatic repulsion of the dispersion without reducing compatibility, so that the storage stability is also excellent at high temperatures, which are harsh conditions such as outdoors.

The emulsion for road paving of the present invention is an O/W type emulsion in which the polyamide (A) and the carboxylic acid compound (B) are dispersed in an aqueous medium.
The aqueous medium is a dispersion medium in which water accounts for the largest proportion by mass. From the viewpoint of storage stability, the water content in the aqueous medium is preferably 60% by mass or more, more preferably 75% by mass or more, and even more preferably 90% by mass or more, and 100% by mass or less.
Examples of components other than water include organic solvents that dissolve in water, such as alkyl alcohols having 1 to 5 carbon atoms, such as methanol and ethanol; dialkyl ketones having 3 to 5 carbon atoms, such as acetone and methyl ethyl ketone; and cyclic ethers, such as tetrahydrofuran.
In one preferred embodiment of the present invention, the aqueous medium consists essentially of water.

The total solid content of the polyamide (A) and the carboxylic acid compound (B) in the road paving emulsion is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of storage stability, and is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less, from the viewpoint of dispersibility.

From the viewpoint of dispersibility, the volume median particle size ( _D50 ) of the emulsion particles in the road paving emulsion is preferably 50 nm or more, more preferably 80 nm or more, even more preferably 100 nm or more, and is preferably 1500 nm or less, more preferably 1000 nm or less, even more preferably 300 nm or less.
The volume median particle size can be appropriately adjusted by adjusting the molecular weight, acid value, and degree of neutralization of the polyamide (A) and by changing the phase inversion emulsification conditions.
In this specification, the volume median particle size ( _D50 ) means the particle size at which the cumulative volume frequency calculated by volume fraction is 50% from the smallest particle size. The volume median particle size ( _D50 ) can be determined by the method described in the Examples below.

[Polyamide (A)]
Polyamide is a polymeric compound having an amide bond (-CONH-) and includes a component derived from a carboxylic acid component and a component derived from an amine component. That is, it is a polycondensation product of a carboxylic acid component and an amine component. Polyamide can be obtained by a condensation polymerization reaction between a carboxylic acid component and an amine component, a ring-opening polymerization reaction of a cyclic lactam, a self-condensation reaction of an amino acid or a derivative thereof, or the like.

(Carboxylic Acid Component)
As the carboxylic acid component, a monobasic carboxylic acid, a dibasic carboxylic acid, or a polymerized fatty acid can be used.
The monobasic carboxylic acid includes saturated or unsaturated aliphatic monobasic carboxylic acids having 4 or more carbon atoms, preferably 8 or more carbon atoms, more preferably 12 or more carbon atoms, and 24 or less carbon atoms, preferably 22 or less carbon atoms.
Specific examples of the saturated aliphatic monocarboxylic acid include butyric acid, valeric acid, lauric acid, palmitic acid, stearic acid, arachidic acid, and behenic acid.
Examples of unsaturated aliphatic monocarboxylic acids include oleic acid, linoleic acid, linolenic acid, eicosenoic acid, erucic acid, and mixed fatty acids obtained from natural fats and oils (tall oil fatty acids, rice bran fatty acids, soybean oil fatty acids, beef tallow fatty acids, etc.).
The dicarboxylic acid may be an aliphatic or aromatic dicarboxylic acid having 4 or more carbon atoms, preferably 6 or more carbon atoms. Specific examples thereof include succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, dodecanedioic acid, phthalic acid, isophthalic acid, and terephthalic acid.

The polymerized fatty acid is a polymer obtained by polymerizing a monobasic fatty acid having an unsaturated bond, or a polymer obtained by polymerizing an ester of a monobasic fatty acid having an unsaturated bond. Examples of the polymerized fatty acid include those obtained by a dehydration condensation reaction of a divalent carboxylic acid derived from vegetable oils and fats.
Examples of monobasic fatty acids having unsaturated bonds include unsaturated fatty acids having a total of 8 to 24 carbon atoms and typically having 1 to 3 unsaturated bonds, and specific examples thereof include oleic acid, linoleic acid, linolenic acid, natural drying oil fatty acids, and natural semi-drying oil fatty acids.
Furthermore, examples of the esterification product of the monobasic fatty acid having an unsaturated bond include esterification products of the above-mentioned monobasic fatty acid having an unsaturated bond and an aliphatic alcohol, preferably an aliphatic alcohol having 1 to 3 carbon atoms.
The polymerized fatty acid, which is a polymer obtained by polymerizing a monobasic fatty acid having an unsaturated bond or an ester of a monobasic fatty acid having an unsaturated bond, is preferably one mainly composed of a dimer. For example, a polymer of an unsaturated fatty acid having 18 or more carbon atoms is commercially available that has a composition of 0 to 10 mass% of a monobasic acid (monomer) having 18 carbon atoms, 60 to 99 mass% of a dibasic acid (dimer) having 36 carbon atoms, and 30 mass% or less of a tribasic acid or more having 54 carbon atoms (trimer or more).
The above carboxylic acid components can be used alone or in combination of two or more kinds, and it is more preferable to use a monobasic carboxylic acid and a polymerized fatty acid in combination.

Among the carboxylic acid components, it is preferable to contain at least a monovalent carboxylic acid, and the content thereof is preferably 5 molar equivalent % or more, more preferably 8 molar equivalent % or more, even more preferably 10 molar equivalent % or more, and preferably 50 molar equivalent % or less, based on the total amount of the carboxylic acid components, from the viewpoint of storage stability.
When a monobasic carboxylic acid and a polymerized fatty acid are used in combination as the carboxylic acid component, the content of the monobasic carboxylic acid is preferably 10 molar equivalent % or more, more preferably 15 molar equivalent % or more, and preferably less than 50 molar equivalent %, more preferably less than 40 molar equivalent %, based on the total amount of the carboxylic acid component. Also, the content of the polymerized fatty acid is preferably 50 molar equivalent % or more, more preferably 60 molar equivalent % or more, and preferably less than 90 molar equivalent %, more preferably less than 85 molar equivalent %, based on the total amount of the carboxylic acid component.

(Amine component)
Examples of the amine component include polyamines, aminocarboxylic acids, and aminoalcohols.

Examples of the polyamine include aliphatic diamines, aliphatic triamines, alicyclic diamines, and aromatic diamines.
The aliphatic diamine is preferably an aliphatic diamine having from 2 to 6 carbon atoms, and examples of such diamine include ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, etc. Among these, ethylenediamine and hexamethylenediamine are preferred.
Examples of the aliphatic triamine include diethylenetriamine, dipropylenetriamine, benzenetriamine, etc. Among these, diethylenetriamine is preferable.
Examples of the alicyclic diamine include isophorone diamine, tricyclodecane diamine, and norbornane diamine. Among these, isophorone diamine is preferable.
Examples of aromatic diamines include xylylenediamine, diphenylmethanediamine, diaminodiphenylsulfone, methylenebischloroaniline, etc. Among these, xylylenediamine is preferred.

From the viewpoint of storage stability, the polyamine contains at least two or more polyamines of the same or different kinds selected from aliphatic diamines, aliphatic triamines, alicyclic diamines and aromatic diamines, at least one of which is an aliphatic diamine. Among them, the amine component contains, as the two or more polyamines, preferably one aliphatic diamine and at least one other aliphatic diamine, one or more aliphatic triamines, one or more alicyclic triamines and one or more aromatic diamines, totaling two or more polyamines, more preferably two or more aliphatic diamines and one or more alicyclic diamines, totaling three or more polyamines.
By containing two or more polyamines with different structures in the amine component, the orientation of the amide group between polyamide molecules can be adjusted. This can reduce the amount of crystallization and hydrogen bonds caused by intermolecular interactions of polyamide, and is therefore considered to be able to suppress the aggregation of the dispersion. Furthermore, by containing two or more polyamines with different structures, it is possible to lower the softening point of the polyamide, and the desired softening point can be easily adjusted. Note that, when the amine component is made of a single type, the polyamide tends to have a high softening point.

As the two or more aliphatic diamines, ethylenediamine and hexamethylenediamine are preferred. As the alicyclic diamine, isophoronediamine is preferred.

In the polyamine, the polyamine species present in the largest amount is preferably an aliphatic diamine, more preferably ethylenediamine. From the viewpoint of storage stability, the amount of the polyamine species present in the largest amount is preferably 55 mol% or more, more preferably 60 mol% or more, even more preferably 65 mol% or more, and preferably 85 mol% or less, more preferably 80 mol% or less, even more preferably 75 mol% or less, based on the total amount of the amine components.
When an alicyclic diamine is contained, the content thereof is preferably 1 mol % or more, more preferably 2 mol % or more, even more preferably 3 mol % or more, and preferably 10 mol % or less, more preferably 8 mol % or less, even more preferably 7 mol % or less, based on the total amount of amines.

(Physical properties of polyamide)
From the viewpoint of storage stability, the softening point of the polyamide used in the present invention is preferably 60° C. or higher, more preferably 70° C. or higher, even more preferably 75° C. or higher, and even more preferably 80° C. or higher, and is preferably 105° C. or lower, more preferably 100° C. or lower, and even more preferably 95° C. or lower.
From the same viewpoint, the acid value of the polyamide is preferably 15 mgKOH/g or more, more preferably 18 mgKOH/g or more, even more preferably 22 mgKOH/g or more, and preferably 50 mgKOH/g or less, more preferably 40 mgKOH/g or less, even more preferably 30 mgKOH/g or less.
From the same viewpoint, the amine value of the polyamide is preferably 0.1 mgKOH/g or more, more preferably 0.2 mgKOH/g or more, even more preferably 0.4 mgKOH/g or more, and preferably 7 mgKOH/g or less, more preferably 5 mgKOH/g or less, even more preferably 3 mgKOH/g or less.
The softening point, acid value and amine value of the polyamide can be measured by the method described in the Examples.
From the same viewpoint, the polyamide preferably has a heat of crystallization (ΔHc) of more than 2 J/g, more preferably 3 J/g or more, even more preferably 4.5 J/g or more, and preferably 13 J/g or less, more preferably 10 J/g or less, even more preferably 8 J/g or less, when cooled at 20° C./min and then 5° C./min in differential scanning calorimetry (DSC) according to JIS-K7121.
The heat of crystallization (ΔHc) is the peak area of the crystallization peak temperature Tc (°C) that appears when a polyamide is heated at a heating rate of 20°C/min and cooled at a rate of 5°C/min. The measurement can be performed by the method described in the Examples.

(Degree of Neutralization)
From the viewpoint of dispersibility, the polyamide may be at least partially neutralized in acid groups. In this case, the amount of the neutralizing agent used is preferably 80 mol% or more, more preferably 90 mol% or more, even more preferably 95 mol% or more, and preferably 140 mol% or less, more preferably 120 mol% or less, even more preferably 110 mol% or less.
Here, the degree of neutralization (mol %) can be specifically determined by the following formula: When the degree of neutralization is 100 mol % or less, it is equivalent to the amount of the neutralizing agent used.
Degree of neutralization (mol %)=[{weight (g) of neutralizing agent added/equivalent weight of neutralizing agent}/[{acid value (mg KOH/g)×weight (g) of polyamide}/(56×1,000)]]×100
Examples of the neutralizing agent used for neutralizing the polyamide include basic compounds. Examples of the basic compound include hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, and calcium hydroxide, ammonia, and organic amines. From the viewpoint of high temperature stability, ammonia or organic amines are preferred. Examples of the organic amines include triethylamine, N,N-diethylethanolamine, N,N-dimethylethanolamine, and triethanolamine. Nitrogen-containing basic substances are preferred, and N,N-dimethylethanolamine is more preferred.

(Production method of polyamide)
The polyamide can be obtained by subjecting a carboxylic acid component and an amine component, preferably a carboxylic acid component containing a monovalent carboxylic acid and a polymerized fatty acid, and an amine component containing a polyamine, to a polycondensation reaction under known reaction conditions.
From the viewpoint of storage stability, the polyamide used in the present invention is preferably made to have an excess molar equivalent ratio of the carboxylic acid component to the amine component. Specifically, the molar equivalent ratio of the carboxyl group of the carboxylic acid component to the amino group of the amine component (carboxyl group/amino group) is preferably more than 1.0/1.0, more preferably 1.15/1.0 or more, even more preferably 1.1/1.0 or more, and is preferably 1.4/1.0 or less, more preferably 1.3/1.0 or less, even more preferably 1.25/1.0 or less.
The polycondensation reaction temperature is preferably 180° C. or higher, more preferably 190° C. or higher, and preferably 250° C. or lower, more preferably 240° C. or lower.
Polyamides can be easily produced by adjusting the reaction temperature and reaction time under the above molar equivalent ratio conditions of the carboxylic acid component and the amine component, and, in some cases, by adding a monovalent carboxylic acid or a monoamine.

[Carboxylic Acid Compound (B)]
The road paving emulsion of the present invention contains at least one carboxylic acid compound (B) selected from branched-chain aliphatic carboxylic acids having from 8 to 24 carbon atoms and linear aliphatic carboxylic acids containing a secondary carboxy group having from 8 to 24 carbon atoms.
The term "secondary carboxy group" refers to a carboxy group in which the carbon atom to which the carboxy group is bonded is a secondary carbon atom having two carbon atoms bonded thereto.

The carboxylic acid compound (B) may be a monocarboxylic acid, a dicarboxylic acid, or a trivalent or higher polycarboxylic acid, and from the viewpoint of storage stability, a monocarboxylic acid is preferred.
From the viewpoint of accelerating the development of water resistance, the carboxylic acid (B) has a carbon number of 8 or more, preferably 10 or more, more preferably 12 or more, and even more preferably 14 or more, and has a carbon number of 24 or less, preferably 23 or less, more preferably 22 or less, and even more preferably 20 or less.
Specific examples of branched chain aliphatic carboxylic acid compounds having from 8 to 24 carbon atoms and secondary carboxy group-containing linear aliphatic carboxylic acid compounds having from 8 to 24 carbon atoms include isostearic acid (2,2,4,8,10,10-hexamethylundecane-5-carboxylic acid), 16-methylheptadecanoic acid, 2-hexyldecanoic acid, 2-ethylhexanoic acid, 4-methylnonanoic acid, octyldecanoic acid, hexyldodecanoic acid, isoarachic acid, 2-propylvaleric acid, etc. These carboxylic acid compounds may be used alone or in combination.

From the viewpoint of storage stability, the content of the carboxylic acid compound (B) in the emulsion for road paving is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 6 parts by mass or more, per 100 parts by mass of the total content of the polyamide (A) and the carboxylic acid compound (B), and is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, even more preferably 14 parts by mass or less.
In other words, the mass ratio of the polyamide (A) to the carboxylic acid compound (B) [(A):(B)] is, from the viewpoint of abrasion resistance, preferably 80:20 or more, more preferably 82:18 or more, even more preferably 86:14 or more, and is preferably 99:1 or less, more preferably 97:3 or less, even more preferably 94:6 or less.

[Method of manufacturing emulsion for road paving]
The emulsion for road paving of the present invention can be produced by a known method for dispersing polyamide. For example, a method of forcibly emulsifying polyamide (A) and carboxylic acid compound (B) in an aqueous medium, optionally in the presence of a surfactant, using an emulsifier, a phase inversion emulsification method, etc. are included. From the viewpoint of storage stability, the method for producing the emulsion for road paving is preferably a phase inversion emulsification method.

[Step 1]
A preferred embodiment of the method for producing an emulsion for road paving includes the following step 1.
Step 1: A step of adding an aqueous medium to an organic solvent solution of a polyamide (A) and a carboxylic acid compound (B) to effect phase inversion emulsification (organic solvent)
The organic solvent solution in step 1 is a solution in which the polyamide (A) and the carboxylic acid compound (B) are dissolved in an organic solvent.
Examples of the organic solvent include acetone, isopropyl alcohol, methyl ethyl ketone, and tetrahydrofuran (THF), and preferred are organic solvents that are water-soluble and have a boiling point lower than that of water.
In particular, the organic solvent is preferably a mixed solvent of isopropyl alcohol and THF. In this case, the mass ratio of isopropyl alcohol/THF is preferably 40/60 or more, more preferably 45/55 or more, and preferably 60/40 or less, more preferably 55/45 or less, and even more preferably 50/50 or less.
The amount of the organic solvent used is preferably 80 parts by mass or more, more preferably 90 parts by mass or more, and 200 parts by mass or less, more preferably 150 parts by mass or less, per 100 parts by mass of the total mass of the polyamide (A) and the carboxylic acid compound (B).
From the viewpoint of storage stability, the temperature of the organic solvent phase (oil phase) during phase inversion emulsification is preferably 10° C. or higher, more preferably 15° C. or higher, even more preferably 20° C. or higher, and is preferably 70° C. or lower, more preferably 50° C. or lower, even more preferably 40° C. or lower.

(Aqueous medium)
In step 1, an aqueous medium is added to the organic solvent solution, preferably with stirring.
As the aqueous medium, the aqueous medium described above can be used.
The amount of the aqueous medium used is preferably 100 parts by mass or more, more preferably 200 parts by mass or more, and 1,000 parts by mass or less, more preferably 600 parts by mass or less, per 100 parts by mass of the total mass of the polyamide (A) and the carboxylic acid compound (B).
In order to neutralize the polyamide (A), a basic compound is preferably further added together with the aqueous medium.
Moreover, from the viewpoint of adjusting the volume median particle size (D ₅₀ ) of the emulsion particles in the road paving emulsion, a surfactant may be further added.
The amount of the surfactant used is preferably 20 parts by mass or less, and more preferably 5 parts by mass or less, based on 100 parts by mass of the polyamide (A).

(Phase inversion emulsification)
In the phase inversion emulsification, an aqueous medium and, if necessary, a basic compound and a surfactant are added, and then the organic solvent is preferably distilled off to invert the phase into an aqueous medium.
The organic solvent is distilled off under reduced pressure conditions of preferably 8 kPa to 50 kPa and at a temperature of preferably 25° C. to 70° C.
It is preferable to distill off the organic solvent so that the content of the organic solvent in the road paving emulsion is preferably 1% by mass or less, more preferably 0.1% by mass or less.
It is also preferable to add a basic compound or the like to the resulting treatment liquid to adjust the pH to 6 or more and 10 or less.

In this manner, an emulsion for road paving, which is a water dispersion, is produced.
The emulsion for road paving of the present invention may be the aqueous dispersion obtained as described above, or may further contain an aqueous medium.

[Road paving composition and colored paving coating composition]
In one embodiment, the road paving emulsion of the present invention can be used in combination with aggregate and a hardener to prepare a road paving composition for forming a surface layer made of a resin on a road pavement. The surface layer formed by the road paving composition protects the pavement surface and improves the durability of the road pavement by hardening the polyamide (A) and the carboxylic acid compound (B). In addition, the aggregate contained in the surface layer roughens the surface, providing a slip effect. Furthermore, when the road pavement is a drainage pavement using an asphalt mixture, the hardened road pavement composition forms a layer to cover the aggregate in the voids of the drainage pavement, and the aggregate can be more firmly bonded.

In another embodiment, the road pavement emulsion of the present invention can be used to prepare a colored pavement paint composition for forming a colored surface layer made of resin on a road pavement by further combining a pigment with the road pavement composition. The colored pavement paint composition can clearly color-code sidewalks, indicate stopping zones, etc., by using the colored surface layer.

〔aggregate〕
Examples of aggregates include natural aggregates such as gravel and sand; processed aggregates such as crushed stone, crushed sand, and fillers; recycled aggregates; and artificial materials such as ceramics and slag. Specific examples of crushed sand include silica sand and limestone. Specific examples of sand include natural silica sand. Of these, silica sand is preferred.
These aggregates can be used alone or in combination of two or more.
From the viewpoint of abrasion resistance, the aggregate content is preferably 300 parts by mass or more, more preferably 400 parts by mass or more, even more preferably 450 parts by mass or more, per 100 parts by mass of the road paving emulsion solids, and is preferably 800 parts by mass or less, even more preferably 700 parts by mass or less, more preferably 600 parts by mass or less.

[Hardening agent]
Examples of the curing agent include a silane coupling agent, an oxazoline-based curing agent, and an isocyanate-based curing agent.
Among these, silane coupling agents are preferred. Specific examples of the silane coupling agent include aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, organosilazane compounds, titanate coupling agents, and the like. Among these, preferred are epoxysilane coupling agents having an alkoxy group and a glycidyl group having 1 to 5 carbon atoms, such as 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and more preferably 3-glycidoxypropylmethyldimethoxysilane.
These curing agents can be used alone or in combination of two or more.
When the curing agent is a silane coupling agent, the content of the silane coupling agent is preferably 5 parts by weight or more, more preferably 6 parts by weight or more, even more preferably 7 parts by weight or more, and preferably 12 parts by weight or less, more preferably 11 parts by weight or less, even more preferably 10 parts by weight or less, based on 100 parts by weight of the solid content of the road paving emulsion.

[Pigments]
The pigment may be either an organic pigment or an inorganic pigment, and a lake pigment or a fluorescent pigment may also be used. If necessary, these pigments may be used in combination with an extender pigment. The pigments may be used alone or in combination of two or more kinds.
Specific examples of organic pigments include azo pigments such as azo lake pigments, insoluble monoazo pigments, insoluble disazo pigments, condensed azo pigments, and chelate azo pigments; and polycyclic pigments such as phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, isoindoline pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, threne pigments, and metal complex pigments.
Specific examples of inorganic pigments include carbon blacks such as furnace black, thermal lamp black, acetylene black, and channel black; metal oxides such as titanium oxide, zinc oxide, iron oxide, red iron oxide, and chromium oxide; and pearlescent pigments.
Examples of the extender pigment include silica, calcium carbonate, and talc.
The hue is not particularly limited, and any chromatic pigment such as yellow, magenta, cyan, blue, red, orange, green, etc. can be used.
The pigment content is preferably 2% by mass or more, more preferably 4% by mass or more, even more preferably 6% by mass or more, based on 100 parts by mass of the solid content of the road paving emulsion, and is preferably 20% by mass or less, more preferably 16% by mass or less, even more preferably 10% by mass or less.

[Other ingredients]
The road paving composition and colored paving coating composition may further contain various known additives such as film-forming assistants, anti-stripping agents, antioxidants, process oils, etc. in addition to the above-mentioned components.
The road paving composition and color paving coating composition can be given flexibility and further improved strength after application by using a film-forming assistant in combination. An example of the film-forming assistant is an aqueous dispersion of a thermoplastic resin having a glass transition temperature of 20° C. or less. The glass transition temperature of the thermoplastic resin is preferably −50° C. or more, more preferably −20° C. or more, and is preferably 5° C. or less, more preferably 0° C. or less.
Specific examples of thermoplastic resins include styrene-acrylic resins, poly(meth)acrylic acid esters, polyvinyl acetate, ethylene-vinyl acetate copolymers, polyurethane, styrene-butadiene rubber, acrylonitrile-butadiene rubber, isoprene rubber, chloroprene rubber, natural rubber, and aqueous latexes thereof. Among these, from the viewpoint of imparting flexibility, styrene-acrylic aqueous dispersions are preferred.

[Paving method]
By applying the road paving composition or colored pavement coating composition of the present invention onto a pavement surface, which is an asphalt pavement layer or a concrete pavement layer, a surface layer or a colored surface layer made of a resin can be formed.
Therefore, the present invention also provides a method for paving a road, which comprises a step of applying the road paving composition or colored paving coating composition onto a paved surface.
Application onto the pavement surface can be carried out, for example, by coating or spraying. The road paving composition and the color paving coating composition can react and harden at room temperature due to the evaporation of water, so the application temperature can be room temperature (e.g., 20° C. or higher and 35° C. or lower).

Various physical properties were measured and evaluated by the following methods.
In the following examples and comparative examples, parts and percentages are by weight unless otherwise specified.

(1) Softening Point of Polyamide The softening point of polyamide was measured by the ring and ball method described in "JIS K2207:2006 Petroleum Asphalt".

(2) Measurement of Acid Value of Polyamide The acid value of the polyamide was measured based on the method of JIS K0070: 1992. However, the measurement solvent was changed from the mixed solvent of ethanol and ether specified in JIS K0070: 1992 to a mixed solvent of methanol and chloroform (methanol:chloroform = 1:1 (volume ratio)).

(3) Measurement of Amine Value of Polyamide The amine value of polyamide was measured based on the method of JIS K7237: 1995. However, the measurement solvent was changed from the mixed solvent of o-nitrotoluene and acetic acid specified in JIS K7237: 1995 to a mixed solvent of methanol and chloroform (methanol:chloroform = 1:1 (volume ratio)).

(4) Measurement of heat of crystallization (ΔHc) of polyamide Using a differential scanning calorimeter "DSC Q20" (manufactured by TA Instruments Japan, Inc.) conforming to JIS-K7121, 0.01 to 0.02 g of a sample was weighed into an aluminum pan, heated to 150°C at a heating rate of 20°C/min, and cooled from that temperature to -10°C at a heating rate of 5°C/min to obtain a crystallization exothermic curve. The heat of crystallization (ΔHc) was calculated from the area of the exothermic peak obtained from the crystallization exothermic curve.

(5) Measurement of volume median particle size ( _D50 ) of polyamide emulsion Measurement device: Laser diffraction type particle size measuring device (manufactured by Horiba, Ltd.)
Measurement conditions: Distilled water was added to the sample to be measured, and the concentration was adjusted to a level that would allow the particle sizes of 30,000 particles to be measured in 20 seconds. The particle sizes of the 30,000 particles were then measured, and the volume median particle size ( _D50 ) was calculated from the particle size distribution obtained.

(6) Measurement of solid content concentration of polyamide emulsion Using an infrared moisture meter (Kett Electric Laboratory, "FD-230"), 5 g of a measurement sample was dried at a drying temperature of 150°C and measurement mode 96 (monitoring time 2.5 minutes, fluctuation range 0.05%), and the moisture content (mass%) of the measurement sample was measured. The solid content concentration was calculated according to the following formula.
Solid content concentration (mass%) = 100 - water (mass%)

Production Example 1 (Production of Polyamide PA1)
The carboxylic acid component including oleic acid (manufactured by Kao Corporation, product name: Lunac O-V), propionic acid, and polymerized fatty acid (dimer acid, manufactured by Tsuno Food Industry Co., Ltd., product name: Tsunodym 205) and the amine component consisting of ethylenediamine (EDA), hexamethylenediamine (HMDA), and isophoronediamine (IPDA) were placed in a four-neck round-bottom flask equipped with a thermometer, a stirring system, a dehydration tube, and a nitrogen blowing tube in the amounts shown in Table 1, the mixture was stirred, and a small amount of nitrogen was blown in to prevent discoloration of the contents, and then the mixture was reacted at 210°C for 3 hours and further under reduced pressure (13.3 kPa) for 2 hours, cooled, and pulverized to obtain polyamide PA1. The results are shown in Table 1.

Production Examples 2 to 7 (Production of Polyamides PA2 to PA7)
Polyamides PA2 to PA7 were obtained in the same manner as in Production Example 1, except that the compositions of the carboxylic acid component and the amine component were as shown in Table 1. The results are shown in Table 1.

Production Example 8 (Production of Polyamide Emulsion Em1)
In a 2L container equipped with a stirrer "Three One Motor BL300" (manufactured by Shinto Scientific Co., Ltd.), a reflux condenser, a dropping funnel, a thermometer and a nitrogen inlet tube, 90 g of the polyamide PA1 obtained in Production Example 1, 10 g of monocarboxylic acid C1 (manufactured by Tokyo Chemical Industry Co., Ltd.: Isosteric Acid: also known as 2,2,4,8,10,10-Hexamethylundecane-5-carboxylic Acid), 50 g of isopropyl alcohol (IPA), and 50 g of tetrahydrofuran (THF) were added, and the polyamide was dissolved at 50 ° C. for 3 hours. After cooling to 30 ° C., a neutralizing agent N1 (2-dimethylaminoethanol) was added to the solution so that the degree of neutralization was 100 mol % with respect to the acid value of polyamide PA1 and carboxylic acid compound C1, and the mixture was stirred for 60 minutes.
Next, while maintaining the temperature at 30°C, 400g of deionized water was added over 120 minutes while stirring at 200 r/min, and phase inversion emulsification was performed. After heating to 50°C, isopropyl alcohol and THF were distilled off under reduced pressure to obtain an aqueous dispersion. After cooling the aqueous dispersion to 30°C while stirring, it was filtered through a 300 mesh wire net to obtain polyamide emulsion Em1. The results are shown in Table 2.

Production Examples 9 to 14 (Production of Polyamide Emulsions Em2 to Em7)
Polyamide emulsions Em2 to Em7 were obtained in the same manner as in Production Example 8, except that the types of polyamide were as shown in Table 2. The results are shown in Table 2.

Production Examples 15 to 21 (Production of Polyamide Emulsions Em8 to Em14)
Polyamide emulsions Em8 to Em14 were obtained in the same manner as in Production Example 8, except that the amount of the carboxylic acid compound or the type of the carboxylic acid compound used was as shown in Table 2. The results are shown in Table 2.

Production Example 22 (Production of Polyamide Emulsion Em15)
A polyamide emulsion Em15 was obtained in the same manner as in Production Example 8, except that the neutralizing agent was changed to Neutralizing Agent N2 (25% aqueous ammonia). The results are shown in Table 2.

Production Example 23 (Production of Polyamide Emulsion Em16)
A polyamide emulsion Em16 was obtained in the same manner as in Production Example 8, except that the organic solvent was 0 g of isopropyl alcohol (IPA) and 100 g of tetrahydrofuran (THF). The results are shown in Table 2.

Examples 1 to 15, Comparative Example 1
20 g of aqueous dispersions prepared by adding deionized water to the polyamide emulsions obtained in Production Examples 8 to 23 to adjust the solid content to 20% were placed in 50 mL screw tube bottles and left to stand in a thermostatic chamber set at 40° C. for 6, 12, 24, and 72 hours. After standing, the screw tube was inverted, and if the paint reached the bottom within 3 seconds, it was marked as ◯. If the paint lost fluidity and did not reach the bottom even after 3 seconds, it was marked as ×.
The results are shown in Table 3.

From Table 3, it can be seen that the polyamide emulsions containing specific carboxylic acid compounds obtained in Production Examples 8 to 17 and Production Examples 19 to 23 do not lose fluidity even when left standing at high temperatures and have excellent storage stability.

Claims (10)

1. An emulsion for road paving comprising: a polyamide (A); and at least one carboxylic acid compound (B) selected from a branched-chain aliphatic carboxylic acid having from 8 to 24 carbon atoms and a linear aliphatic carboxylic acid containing a secondary carboxy group having from 8 to 24 carbon atoms, wherein the mass ratio of the polyamide (A) to the carboxylic acid compound (B) [(A):(B)] is 80:20 or more and 99:1 or less . The road paving emulsion according to claim 1, wherein the acid value of the polyamide (A) is 15 mg KOH/g or more and 50 mg KOH/g or less. The road paving emulsion according to claim 1 or 2, wherein the heat of crystallization (ΔHc) of polyamide (A) is 2 J/g or more and 13 J/g or less. The road paving emulsion according to any one of claims 1 to 3, wherein the carboxylic acid compound (B) is a monocarboxylic acid. A method for producing an emulsion for road paving, comprising the following step 1:
Step 1: A step of adding an aqueous medium to an organic solvent solution containing a polyamide (A) and a carboxylic acid compound (B), in which the mass ratio of the polyamide (A) to the carboxylic acid compound (B) [(A):(B)] is 80:20 or more and 99:1 or less , to perform phase inversion emulsification. The method for producing an emulsion for road paving according to claim 5, wherein the temperature of the oil phase during phase inversion emulsification is 50°C or less. The road paving emulsion according to any one of claims 1 to 4, for use in preparing a road paving composition. An emulsion for road paving according to any one of claims 1 to 4 for use in preparing a colored paving paint composition. A road paving composition comprising the road paving emulsion according to any one of claims 1 to 4 and silica sand. A colored pavement paint composition according to claim 9, further comprising a pigment.