JP7724092B2 - Coating resin composition for civil engineering and construction, cured film, coating method for civil engineering and construction structures, method for preventing tile peeling, and structure - Google Patents

Description

The present invention relates to a coating resin composition for civil engineering and architectural use, a cured film, a coating method for civil engineering and architectural structures, a method for preventing tile peeling, and a structure. In particular, it relates to an exterior wall surface protection method for preventing tiles from peeling from structures with tiled exterior walls.

In recent years, buildings and other structures with tiles attached to their exterior walls have been facing problems with tiles falling off due to deterioration over time. Furthermore, concrete fragments have also fallen from concrete structures such as the inner walls of tunnels, highway piers, railway piers, and bridges.

It is known that tile peeling can be caused by a variety of factors. Such factors include, for example, poor installation, damage to the tile or underlying mortar due to impacts such as earthquakes or collisions, deterioration of the underlying mortar due to deterioration factors seeping into the exterior wall surface between the tile joints, and mortar peeling due to differences in shrinkage rates relative to the structure. The scale of peeling accidents is known to range from small-scale incidents such as tiles falling due to loose ceramic fragments to large-scale incidents such as the entire underlying mortar peeling off.

In order to prevent such tile peeling, various methods are known for buildings and other structures with tiles attached to their exterior walls. For example, one known method is to provide a transparent resin layer on the exterior wall surface in order to maintain the appearance of the tile finish. Patent Document 1 describes such a method, in which an organic solvent-based resin composition is applied to the exterior wall surface of a structure to provide a transparent resin layer. However, using an organic solvent-based resin composition is undesirable from a safety perspective, as it poses risks such as fire and workers inhaling the organic solvent, and there is a tendency for complaints about odors, particularly from residents of apartment buildings and other buildings, to become frequent.

For the above reasons, there is a demand for the use of water-based resin compositions rather than organic solvent-based resin compositions for exterior wall surface protection. Patent Document 2 describes applying a water-based resin composition to the exterior wall surface of a structure.

JP 2011-069160 A JP 2019-035240 A

However, the aqueous resin composition described in Patent Document 2 uses a metal-based crosslinking agent as a crosslinking agent to ensure sufficient tensile elongation in the cured film. When using a cured film obtained from such an aqueous resin composition on exterior walls that may be exposed to high temperatures and humid conditions, particularly during sunlight, the film may not have sufficient water whitening resistance.

Furthermore, when conventional waterborne resin compositions are adjusted to the required viscosity to achieve good coatability, components in the waterborne resin composition can cause whitening of the coating or cured film obtained by applying the waterborne resin composition. Therefore, with conventional waterborne resin compositions, there are currently only a limited number of construction methods that offer both ease of application and satisfactory performance, particularly in applications that require high functionality in maintaining appearance and preventing tile peeling.

The present invention aims to provide a resin composition for civil engineering and architectural coatings that has good workability and is capable of forming a cured product with good transparency and water-whitening resistance. The present invention also aims to provide a cured film, a method for coating civil engineering and architectural structures, a method for preventing tile peeling, and a structure using such a resin composition for civil engineering and architectural coatings.

One aspect of the present invention relates to a coating resin composition for civil engineering and construction (hereinafter, sometimes simply referred to as a "resin composition"). The resin composition includes a polyurethane resin (a) having a polycarbonate structure (hereinafter, sometimes simply referred to as a "polyurethane resin (a)"), an aqueous medium (b), and a crosslinking agent (c) reactive with an acidic group or a salt thereof (hereinafter, sometimes simply referred to as a "crosslinking agent (c)"). The resin composition satisfies at least one of the following conditions A and B:
Condition A: The acid value of the nonvolatile matter in the resin composition is 5 to 17 mgKOH/g.
Condition B: The acid value of the polyurethane resin (a) is 5 to 22 mgKOH/g.

The resin composition can be dried at room temperature to evaporate low-boiling components, including the aqueous dispersion medium, to form a cured product. During this process, the polyurethane resin (a) and crosslinker (c) react to form crosslinks in the cured product, strengthening it. Furthermore, the acid value is reduced, resulting in a cured product with excellent water resistance. Furthermore, the resin composition can suppress whitening of the cured film by ensuring that at least one of the acid values of the nonvolatile content in the resin composition and the polyurethane resin (a) is within a specified range. Furthermore, the resin composition has a sufficient pot life, free from the limitations imposed by two-component materials and the risk of poor curing due to inconsistent blending ratios. Therefore, it can be used effectively on various shapes, such as uneven or angular portions, on the surface of substrates (e.g., concrete).

Preferred embodiments of the resin composition are shown below. A plurality of these preferred embodiments can be combined.
(1) Both conditions A and B are satisfied.
(2) The polyurethane resin (a) has an acidic group.
(3) The polyurethane resin (a) has a structure derived from a linear aliphatic diol in the polycarbonate structure of the polyurethane resin (a).
(4) The polyurethane resin (a) has a structure derived from an aliphatic polyisocyanate.
(5) The crosslinking agent (c) contains a compound having a carbodiimide group.
(6) The resin composition further contains a thixotropy-imparting agent (e), and the content of the thixotropy-imparting agent (e) is 20 mass % or less based on the total amount of nonvolatile components of the resin composition.
(7) The viscosity of the resin composition is measured in accordance with JIS-Z8803:2011 (Method for measuring viscosity of liquids) using an E-type viscometer with a 3° x R9.7 cone rotor at a rotation speed of 5 rpm and 23°C. The viscosity is 6.0 to 60 Pa s.
(8) The resin composition is applied and subjected to a sagging test in accordance with ASTM D4400, and the coating thickness of the coating resin composition for civil engineering and construction, which shows no run-in, is 0.75 mm or more.
(9) When a coating film formed from the resin composition is cured for 7 days under standard conditions of 23°C and 50% RH to form a cured film, the grip elongation at 23°C based on JIS A 6021:2011, measured on a cured film with a film thickness of 0.3 mm, is 150% or more.
(10) When a coating film formed from the resin composition is cured for 7 days under standard conditions of 23°C and 50% RH to form a cured film, the total light transmittance measured for a cured film having a thickness of 0.3 mm is 10% or more.
(11) To be used for preventing tile peeling, waterproofing of buildings, preventing concrete structures from peeling, protecting concrete structures, or waterproofing of concrete slabs.

Another aspect of the present invention relates to a cured film. The cured film comprises a cured product of the above-described resin composition.

Preferred embodiments of the cured film are shown below. Multiple of these preferred embodiments can be combined.

(1) The grip elongation at 23 ° C. based on JIS A 6021:2011 measured at a film thickness of 0.3 mm is 150% or more.
(2) The total light transmittance measured at a film thickness of 0.3 mm is 10% or more.
(3) The haze measured at a film thickness of 0.3 mm is 70% or less.

Another aspect of the present invention relates to a method for coating a civil engineering or architectural structure. The coating method includes a step of applying the above-described resin composition to the civil engineering or architectural structure.

Another aspect of the present invention relates to a method for preventing tile peeling. The method includes the steps of fixing the surface of an existing tiled exterior wall with metal anchors and covering the exterior wall surface with a coating layer. The coating layer contains a layer containing a cured product of the resin composition described above.

Another aspect of the present invention relates to a structure. The structure includes an exterior wall structure including tiles and a coating layer provided on the exterior wall structure.

One embodiment of the coating layer includes a layer containing a cured product of the resin composition described above. Another embodiment of the coating layer includes a first layer and a second layer, in this order from the exterior wall structure. Here, the first layer is a resin layer of any of acrylic resin, acrylic styrene resin, urethane resin, epoxy resin, and vinyl acetate resin. The second layer is a layer containing a cured product of the resin composition described above. In this embodiment, the coating layer may further include a third layer, which is a resin layer of any of urethane resin, fluororesin, and acrylic silicone resin, on the second layer opposite to the first layer. Another embodiment of the coating layer includes a second layer and a third layer, in this order from the exterior wall structure.

The structure may further comprise metal anchors that hold tiles and/or coating layers included in the exterior wall structure.

The present invention provides a resin composition for civil engineering and architectural coatings that has good workability and is capable of forming a cured product with good transparency and water whitening resistance. The present invention also provides a cured film, a method for coating civil engineering and architectural structures, a method for preventing tile peeling, and a structure using the resin composition for civil engineering and architectural coatings.

Embodiments of the present invention are described below. However, the present invention is not limited to the following embodiments.

As used herein, the term "civil engineering and construction use" in the context of a coating resin composition for civil engineering and construction means that the coating resin composition is used in the civil engineering field, such as bridges, elevated roads, dams, tunnels, roads, and land development; and in the architectural field, such as buildings, condominiums, and homes. As used herein, a "civil engineering and construction coating resin composition" can be used, for example, in coatings, paints (top coats, intermediate coats, and primers), primers, top coats, paints, sprays, varnishes, and the like.

<Coating resin composition for civil engineering and construction>
A coating resin composition for civil engineering and construction (resin composition) according to one embodiment includes a polyurethane resin (a), an aqueous medium (b), and a crosslinking agent (c). The resin composition satisfies at least one of the following conditions A and B, and preferably satisfies both conditions A and B:
Condition A: The acid value of the nonvolatile matter in the resin composition is 5 to 17 mgKOH/g.
Condition B: The acid value of the polyurethane resin (a) is 5 to 22 mgKOH/g.

[Polyurethane resin (a) having a polycarbonate structure]
The polyurethane resin (a) preferably has a polyol-derived structure and a polyisocyanate-derived structure, and has an acidic group (an acidic group structure). When the polyurethane resin (a) has an acidic group having a predetermined acid value, it tends to be easy to obtain a resin composition that has good workability and is capable of forming a cured product having good transparency and water whitening resistance.

As long as the polyurethane resin (a) has a polycarbonate structure, one type may be used alone, or two or more types may be used in combination. When two or more types of polyurethane resin (a) are used in combination, the polyurethane resins (a) as a whole must satisfy the acid value requirement of condition B, and polyurethane resins that do not satisfy the acid value requirement of condition B on their own (polyurethane resins with an acid value of less than 5 mg KOH/g or more than 22 mg KOH/g) can be used in combination.

The polyurethane resin (a) may have, for example, a polyol-derived structure, a polyisocyanate-derived structure, and an acidic group-containing polyol.

(Polyol-derived structure)
In this embodiment, the polyol-derived structure in the polyurethane resin (a) refers to a partial structure of the molecular structure of the polyol other than the group involved in the polyurethane-forming reaction. The polyol-derived structure may have a structure derived from a polycarbonate polyol. The polyol-derived structure may be a structure derived from a polyol not containing an acidic group.

The "polycarbonate polyol-derived structure" refers to the partial structure of the polycarbonate polyol molecular structure other than the groups involved in the urethane reaction. The structure of polyurethane resin (a) may contain structures derived from multiple types of polyols in relation to the polycarbonate polyol.

Examples of polycarbonate polyols that introduce a polycarbonate polyol-derived structure into polyurethane resin (a) include polycarbonate polyols having a structure derived from a polyol of a linear aliphatic diol, a branched aliphatic diol, or an alicyclic diol. A structure derived from a polyol of a linear aliphatic diol, a branched aliphatic diol, or an alicyclic diol refers to the partial structure of the polyol molecule of a linear aliphatic diol, a branched aliphatic diol, or an alicyclic diol other than the groups involved in the carbonation reaction.

Examples of linear aliphatic diols include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, and 1,9-nonanediol. The linear aliphatic diol preferably has 4 to 9 carbon atoms, more preferably 6 carbon atoms.

Examples of branched aliphatic diols include 2-methyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, and 2-methyl-1,9-nonanediol.

Examples of alicyclic aliphatic diols include 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanediol, 1,3-cyclopentanediol, and 1,4-cycloheptanediol.

Among these, linear aliphatic diols, due to the absence of tertiary carbons, tend to generate fewer radicals due to C-H bond cleavage when irradiated with light, etc. Furthermore, linear aliphatic diols tend to lower the glass transition temperature of polyurethane resin (a) and improve film-forming properties when dried at room temperature. For these reasons, the polycarbonate polyol is preferably a polycarbonate polyol having a structure derived from a linear aliphatic diol, more preferably a polycarbonate polyol having a structure derived from a linear aliphatic diol having 4 to 9 carbon atoms, and even more preferably a polycarbonate polyol having a structure derived from a linear aliphatic diol having 6 carbon atoms.

The number-average molecular weight of the polycarbonate polyol can be adjusted appropriately depending on the purpose, but is preferably 200 to 5,000, more preferably 200 to 4,000, and even more preferably 300 to 3,000. Setting the number-average molecular weight of the polycarbonate polyol within this range makes the polycarbonate polyol easier to handle and tends to improve the low-temperature properties of polyurethane resins derived from the polycarbonate polyol. The number-average molecular weight refers to the number-average molecular weight calculated based on the hydroxyl value measured in accordance with JIS K 1557-1:2007. Specifically, the hydroxyl value of the polycarbonate polyol is measured, and the hydroxyl value is calculated using the terminal group determination method using the formula (56.1 x 1000 x valence) / hydroxyl value. In this formula, the unit of hydroxyl value is [mgKOH/g], and the valence is the number of hydroxyl groups per molecule.

The polyol-derived structure may have a structure derived from a polyol other than a polycarbonate polyol, in addition to a structure derived from a polycarbonate polyol. Examples of polyols other than polycarbonate polyols include linear or branched aliphatic polyols having 2 to 10 carbon atoms, aliphatic polyols having an alicyclic structure having 6 to 12 carbon atoms, polyester polyols, polyether polyols, polycarbonate polyester polyols, polyoxyalkylene polyols, polyesteramide polyols, polyether-polyester polyols, poly(meth)acrylic polyols, and (hydrogenated) polybutadiene polyols.

(Polyisocyanate-derived structure)
In the present embodiment, the polyisocyanate-derived structure in the polyurethane resin (a) refers to a partial structure of the molecular structure of the polyisocyanate other than the groups involved in the polyurethane-forming reaction.

Examples of polyisocyanates for introducing polyisocyanate-derived structures into polyurethane resin (a) include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, and 2,6-diisocyanatomethyl caproate. aliphatic polyisocyanates such as bis(2-isocyanatoethyl) fumarate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexanoate; isophorone diisocyanate (IPDI), 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, methylcyclohexylene diisocyanate (hydrogenated TDI), bis(2-isocyanatoethyl) methylisocyanate, and bis(2-isocyanatoethyl) methylisocyanate; aliphatic polycyanates having an alicyclic structure, such as 2,5-norbornane diisocyanate, 2,6-norbornane diisocyanate, and the like; 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate (TDI), 2,6-tolylene diisocyanate, and 4,4'-diphenylenemethane diisocyanate (MDI); Examples include aromatic polyisocyanates having an aromatic structure, such as 2,4-diphenylmethane diisocyanate, 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, m-isocyanatophenylsulfonyl isocyanate, and p-isocyanatophenylsulfonyl isocyanate.

Among these, a structure derived from an aliphatic polyisocyanate is preferred because it is less prone to yellowing due to light irradiation. A structure derived from a polyisocyanate that prevents crystallization of the polyurethane resin (a) and exhibits stable physical properties over the long term is preferably a structure derived from an aliphatic polyisocyanate having an alicyclic structure, more preferably a structure derived from a polyisocyanate having an asymmetric structure, and even more preferably a structure derived from isophorone diisocyanate.

(Structure derived from acidic group-containing polyol)
In this embodiment, the structure derived from an acidic group-containing polyol refers to a partial structure of the molecular structure of the acidic group-containing polyol other than the group involved in the polyurethane-forming reaction. Examples of polyols that introduce a structure derived from an acidic group-containing polyol into polyurethane include polyol compounds having at least one acidic group in the molecule. The acidic group is not particularly limited, and examples include a carboxy group, a sulfonyl group, a phosphate group, and a phenolic hydroxyl group. The structure derived from an acidic group-containing polyol is preferably a structure derived from a carboxylic acid group-containing polyol.

The type of acidic group-containing polyol is not particularly limited, but specific examples include dimethylolalkanoic acids such as 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid, N,N-bishydroxyethylglycine, N,N-bishydroxyethylalanine, 3,4-dihydroxybutanesulfonic acid, and 3,6-dihydroxy-2-toluenesulfonic acid. Among these, alkanoic acids having 4 to 12 carbon atoms and two methylol groups (dimethylolalkanoic acids) are preferred from the standpoint of availability. Among these, dimethylolalkanoic acids are preferred because of their excellent reactivity with crosslinking agents, and 2,2-dimethylolpropionic acid or 2,2-dimethylolbutanoic acid are more preferred, with 2,2-dimethylolpropionic acid being even more preferred. The structure of polyurethane resin (a) may contain structures derived from multiple types of acidic group-containing polyols.

(Characteristics of polyurethane resin (a))
In the polyurethane resin (a) of this embodiment, the total amount of urethane bonds and urea bonds in the polyurethane resin (a) is preferably 20 to 40 mass %, more preferably 20 to 30 mass %, and even more preferably 20 to 26 mass %, based on the total amount of the polyurethane resin (a). When the total amount is within such a range, the adhesion between the coating film (or cured film) formed from the resin composition and the substrate tends to be higher, and the mechanical properties such as elastic modulus and stress of the cured film derived from the resin composition tend to be better.

The total content of urethane bonds and urea bonds can be controlled by the molecular weights of the polyisocyanate, polyol, acidic group-containing polyol, and chain extender, the number of hydroxyl groups, isocyanato groups, and amino groups per molecule, and the proportion of each raw material used in polyurethane resin (a).

The acid value (mg KOH/g) of the polyurethane resin (a) can be determined by JIS K5601:1999 Acid Value (Titration Method). In this analysis method, the titrant, solvent, etc. can be appropriately selected depending on the components in the resin composition. Alternatively, the acid value of the polyurethane resin (a) may be calculated based on the following formula instead of this analysis method.
Acid value (mg KOH/g) of polyurethane resin (a) = molar amount (mmol) of acidic groups (carboxylic acid groups) in polyurethane resin (a) ÷ polyurethane resin (a) (g) × 56.1

The acid value of the polyurethane resin (a) may be 5 to 22 mgKOH/g (Condition B). When two or more polyurethane resins (a) are used in combination, the acid value of the polyurethane resin (a) refers to the acid value of the polyurethane resin (a) as a whole. When the acid value of the polyurethane resin (a) is 5 mgKOH/g or higher, the polyurethane resin (a) tends to be more easily dispersed in an aqueous medium. When the acid value of the polyurethane resin (a) is 22 mgKOH/g or lower, water resistance tends to be improved. When the acid value of the polyurethane resin (a) exceeds 22 mgKOH/g, the amount of hard segments increases, making the resin harder and reducing elongation and out-of-plane bending performance, since low-molecular-weight diols are typically used to introduce acidic groups. The acid value of the polyurethane resin (a) is preferably 7 to 22 mgKOH/g, more preferably 10 to 20 mgKOH/g.

The acid value of polyurethane resin (a) can be adjusted, for example, by adjusting the amount of acidic groups introduced or by combining polyurethane resins (a) with different acid values.

The weight-average molecular weight of polyurethane resin (a) is preferably 25,000 to 10,000,000, more preferably 50,000 to 5,000,000, and even more preferably 100,000 to 1,000,000. The weight-average molecular weight is measured by gel permeation chromatography (GPC), and a converted value obtained from a previously prepared calibration curve of standard polystyrene can be used. When the weight-average molecular weight is 25,000 or more, a good coating film tends to be obtained by drying the resulting resin composition containing polyurethane resin (a). When the weight-average molecular weight is 10,000,000 or less, the drying properties of the resin composition tend to be improved.

The content of polyurethane resin (a) is preferably 10 to 99% by mass, and more preferably 30 to 90% by mass, based on the total amount of nonvolatile content of the resin composition. Note that, in this specification, the nonvolatile content of the resin composition can be determined by known methods, such as the heating residue method specified in JIS K5601-1-2:2008.

In addition to polyurethane resin (a), the resin composition of this embodiment may also contain polyurethane resin (a') (hereinafter sometimes simply referred to as "polyurethane resin (a')") that does not have a polycarbonate structure. Polyurethane resin (a') has a different polyol-derived structure from polyurethane resin (a), and the polyol-derived structure does not have a polycarbonate polyol-derived structure. Examples of polyols used to introduce such polyol-derived structures into polyurethane resin (a') include polyester polyols, polyether polyols, polycarbonate polyester polyols, polyoxyalkylene polyols, polyesteramide polyols, polyether-polyester polyols, poly(meth)acrylic polyols, and (hydrogenated) polybutadiene polyols.

The content of polyurethane resin (a') is preferably 0 to 90 mass% and more preferably 0 to 50 mass% based on the total amount of nonvolatile matter in the resin composition.

[Aqueous medium (b)]
Examples of the aqueous medium (b) include tap water, ion-exchanged water, distilled water, and ultrapure water. Among these, ion-exchanged water is preferred as the aqueous medium (b) from the viewpoints of ease of availability and suppression of particle destabilization due to the influence of salts. Furthermore, the aqueous medium (b) may be a mixture of water and a water-miscible organic solvent. Examples of such organic solvents include alcohol solvents such as methanol, ethanol, n-propanol, and isopropanol; ketone solvents such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ether solvents of polyalkylene glycols; and lactam solvents such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone. It should be noted that a plurality of aqueous media (b) may be used in combination.

The content of the aqueous medium (b) is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass, based on the total amount of the polyurethane resin (a) and the aqueous medium (b).

(Aqueous polyurethane resin dispersion)
The polyurethane resin (a) of this embodiment can be suitably in the form of an emulsion or dispersion in which the polyurethane resin (a) is dispersed in the form of fine particles in an aqueous medium (b) (hereinafter, this may be referred to as an "aqueous polyurethane resin dispersion" or "PUD"). When such an aqueous polyurethane resin dispersion is used, the resin composition can be said to contain the aqueous polyurethane resin dispersion containing the polyurethane resin (a) and the aqueous medium (b), and the crosslinking agent (c).

Methods for dispersing polyurethane resin (a) in aqueous medium (b) include self-emulsification, in which a structure derived from an acidic group-containing polyol is introduced into polyurethane resin (a) and then neutralized with an amine or the like, or forced emulsification, which uses an external emulsifier. These are classified as cationic, anionic, or nonionic depending on the polarity of the acidic group. Self-emulsification is preferred as a method for dispersing polyurethane resin (a) in aqueous medium (b), as there is less concern about bleed-out due to low-molecular-weight emulsifiers. Anionic methods, particularly those using carboxy groups, are also preferred, as they can reduce the concentration of carbonyl groups (acid value) using crosslinker (c), described below, thereby reducing the amount of hydrophilic groups in the cured film and improving water resistance.

(Method for producing aqueous polyurethane resin dispersion)
The aqueous polyurethane resin dispersion of the present embodiment contains a polyurethane resin (a) having a structure derived from the polyol, a structure derived from the polyisocyanate, and a structure derived from the acidic group-containing polyol, and an aqueous medium (b) for dispersing the polyurethane resin (a).

The aqueous polyurethane resin dispersion may be, for example,
a step (α) of reacting the polyol, the polyisocyanate, and the acidic group-containing polyol to obtain a polyurethane prepolymer;
a step (β) of neutralizing the acidic groups of the polyurethane prepolymer;
a step (γ) of dispersing the neutralized polyurethane prepolymer in an aqueous medium;
a step (δ) of reacting the isocyanato group of the polyurethane prepolymer with a chain extender to obtain an aqueous polyurethane resin;
It can be produced by a method comprising:

The above step (α) is preferably carried out by adding at least one type of aqueous organic solvent to the reaction system. There are no particular restrictions on the type of aqueous organic solvent, as long as it is a liquid that is soluble in water and does not inhibit the urethanization reaction. Specific examples include alkyl ether solvents of polyalkylene glycols, such as dipropylene glycol dimethyl ether, and lactams, such as N-ethylpyrrolidone.

The step (β) of neutralizing the acidic groups of the polyurethane prepolymer and the step (γ) of dispersing the polyurethane prepolymer in an aqueous medium may be carried out simultaneously, and the step (γ) of dispersing the polyurethane prepolymer in an aqueous medium and the step (δ) of reacting it with a chain extender to obtain an aqueous polyurethane resin may be carried out simultaneously.

The method for dispersing the polyurethane prepolymer in the aqueous medium (b) in step (γ) is not particularly limited, but can be achieved by adding the polyurethane prepolymer or polyurethane prepolymer solution while stirring the aqueous medium (b) with a homomixer or homogenizer. Alternatively, the aqueous medium may be added to the polyurethane prepolymer solution and dispersed. In this case, the proportion of the polyurethane prepolymer is preferably 5 to 60% by mass, and more preferably 20 to 50% by mass, based on the total amount of the polyurethane prepolymer and aqueous medium.

(Polyurethane prepolymer)
The polyurethane prepolymer of this embodiment is obtained by reacting the polyol, the polyisocyanate, and the acidic group-containing polyol. The ratio of the number of moles of isocyanato groups of the polyisocyanate compound to the total number of moles of hydroxyl groups of the polyol and the acidic group-containing polyol is preferably 1.1 to 2.5, more preferably 1.2 to 2.2, and even more preferably 1.3 to 2.0.

A catalyst can also be used when reacting polyols and acidic group-containing polyols with polyisocyanates to obtain polyurethane prepolymers.

The catalyst is not particularly limited, but examples include salts of metals with organic or inorganic acids, such as tin-based catalysts (trimethyltin laurate, dibutyltin dilaurate, etc.) and lead-based catalysts (lead octoate, etc.); organometallic derivatives; amine-based catalysts (triethylamine, N-ethylmorpholine, triethylenediamine, etc.); and diazabicycloundecene-based catalysts. Of these, dibutyltin dilaurate is preferred from the standpoint of reactivity.

The reaction between the polyol and acidic group-containing polyol and the polyisocyanate may be carried out solventlessly or with the addition of an organic solvent. Examples of organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, N-ethylpyrrolidone, ethyl acetate, diethylene glycol butyl ether, and dipropylene glycol monomethyl ether. Among these, acetone, methyl ethyl ketone, or ethyl acetate is preferred as the organic solvent, since it allows the polyurethane prepolymer to be dispersed in water, subjected to a chain extension reaction, and then removed by heating under reduced pressure. Furthermore, N-methylpyrrolidone, N-ethylpyrrolidone, or dipropylene glycol monomethyl ether are preferred because they function as film-forming aids when forming a coating film from the resulting aqueous polyurethane resin dispersion.

(Neutralizing agent)
In order to disperse the polyurethane prepolymer in water, a basic component can be added to the polyurethane prepolymer solution to neutralize the acid groups derived from the acid group-containing polyol contained in the polyurethane prepolymer.

Basic components that can be used for neutralization include organic amines such as trimethylamine, triethylamine, triisopropylamine, tributylamine, triethanolamine, N-methyldiethanolamine, N-phenyldiethanolamine, dimethylethanolamine, diethylethanolamine, N-methylmorpholine, and pyridine, inorganic alkalis such as sodium hydroxide and potassium hydroxide, and ammonia. Among these, the basic component is preferably an organic amine, and of the organic amines, triethylamine is preferred.

The basic component is preferably added to the polyurethane prepolymer solution directly or as an aqueous solution. The amount added may be 0.5 to 2 equivalents, preferably 0.7 to 1.5 equivalents, and more preferably 0.85 to 1.3 equivalents, relative to the acidic groups in the polyurethane prepolymer. Note that multiple types of these neutralizing agents may be used in combination.

The content of aqueous medium (b) in the aqueous polyurethane resin dispersion is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass, based on the total amount of polyurethane resin (a) and aqueous medium (b).

(Chain extender)
In the production of the aqueous polyurethane resin dispersion, a chain extender can be used to increase the molecular weight.

The chain extender used can be selected appropriately depending on the purpose or application, but examples include water; ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,10-decanediol, 1,1-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, tricyclodecanedimethanol, xylylene glycol, bis(p-hydroxy)diphenyl, bis(p-hydroxyphenyl)propane, 2,2-bis[4-(2-hydroxyethoxy)phenyl]propane, bis[4-(2-hydroxy Examples include low molecular weight polyols such as 1,1-bis[4-(2-hydroxyethoxy)phenyl]sulfone and 1,1-bis[4-(2-hydroxyethoxy)phenyl]cyclohexane; high molecular weight polyols such as polyester polyols, polyesteramide polyols, polyether polyols, polyetherester polyols, polycarbonate polyols, and polyolefin polyols; and polyamines such as ethylenediamine, isophoronediamine, 2-methyl-1,5-pentanediamine, aminoethylethanolamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine.

For details on chain extenders, see, for example, "Latest Polyurethane Application Technology" (CMC Corporation, 1985), and for details on polymer polyols, see, for example, "Polyurethane Foam" (Kobunshi Kankokai, 1987).

Multiple types of chain extenders may be used in combination. The temperature for the reaction between the polyurethane prepolymer and the chain extender is 0 to 50°C, preferably 0 to 40°C. The reaction time varies depending on the reaction temperature, but is typically 0.1 to 5 hours, preferably 0.2 to 3 hours.

The amount of chain extender added is preferably equal to or less than the equivalent of the isocyanato group that will serve as the chain extension initiation point in the resulting urethane polymer. If the amount of chain extender added is equal to or less than the equivalent of the isocyanato group, it is possible to avoid a decrease in the molecular weight of the urethane polymer obtained by chain extension and a decrease in the strength of the cured film. The chain extender can be added after or during dispersion of the polyurethane prepolymer in the aqueous medium. Chain extension can also be carried out using water. In this case, the water used as the aqueous medium doubles as the chain extender.

[Crosslinking agent (c) reactive with acidic groups or salts thereof]
The resin composition of the present embodiment contains a crosslinking agent (c), which allows a cured product of the resin composition to be formed, and can improve the water resistance of a cured film containing the cured product.

The crosslinking agent (c) is not particularly limited as long as it is a compound that reacts with the acidic groups (preferably carboxylic acid groups) or salts thereof of the polyurethane resin (a). Examples include compounds having carbodiimide groups, compounds having oxazoline groups, amino resins, polyisocyanates, blocked polyisocyanates, melamine resins, and polyvalent metal complexes. Among these, the crosslinking agent (c) is preferably a compound having a carbodiimide group, polyisocyanates, blocked polyisocyanates, or polyvalent metal complexes, as these have excellent reactivity with carboxylic acids at room temperature, do not react in the presence of an aqueous medium, and are easily converted into a one-component product. The crosslinking agent (c) is more preferably a compound having a carbodiimide group, as these have excellent water-whitening resistance.

The compound having a carbodiimide group may be, for example, an organic compound having multiple NCN groups in one molecule. Typically, one carbonyl group is bonded to one NCN group, so having multiple NCN groups allows multiple molecules to bond to the polyurethane resin (a) and form a crosslink. Examples of organic compounds having multiple NCN groups in one molecule include compounds represented by the following general formula (1):

In formula (1), R ¹ , R ² , and R ³ represent organic groups, and n represents an integer of 2 or greater. The organic groups are preferably hydrophilic organic groups.

When the polyurethane resin (a) has an acid value and the crosslinking agent (c) is a compound having a carbodiimide group, the resin composition has an equivalent ratio of the carbodiimide group in the crosslinking agent to the acid value in the coating resin composition for civil engineering and construction, calculated by the following formula (B), of preferably 0.1 or more and less than 2.0, more preferably 0.1 or more and less than 1.2, and even more preferably 0.3 or more and less than 1.2.
Equivalent ratio = Concentration of crosslinking agent (c) in coating resin composition for civil engineering and construction (% by mass) ÷ Carbodiimide group equivalent of crosslinking agent (c) (g/mol) ÷ Concentration of non-volatile matter in coating resin composition for civil engineering and construction (% by mass) ÷ Acid value (mg KOH/g) × 56.1 × 1000 (Formula (B))

Commercially available compounds containing carbodiimide groups include the Carbodilite series manufactured by Nisshinbo Chemical Inc. Specific product names include, for example, water-soluble types "SV-02," "V-02," "V-02-L2," and "V-04"; emulsion types "E-01," "E-02," and "E-05"; organic solution types "V-01," "V-03," "V-07," and "V-09"; and solventless type "V-05." Among these, "E-05" is preferred due to its excellent long-term storage stability.

Compounds containing an oxazoline group are generally obtained by polymerizing addition-polymerizable oxazolines such as 2-vinyl-2-oxazoline, 2-vinyl-4-methyl-2-oxazoline, and 2-isopropenyl-2-oxazoline. Compounds containing an oxazoline group may be copolymerized with other monomers as needed. The polymerization method for obtaining compounds containing an oxazoline group is not particularly limited, and known polymerization methods can be used. Commercially available compounds containing an oxazoline group include the Epocross series manufactured by Nippon Shokubai Co., Ltd. Specific product names include water-soluble types "WS-500" and "WS-700" and emulsion types "K-1010E," "K-1020E," "K-1030E," "K-2010E," "K-2020E," and "K-2030E."

Examples of amino resins include partially or fully methylolated amino resins obtained by reacting an amino component with an aldehyde component. Examples of amino components include melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide. Examples of aldehyde components include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde.

Examples of polyisocyanates include compounds having two or more isocyanate groups per molecule, such as hexamethylene diisocyanate and trimethylhexamethylene diisocyanate.

Blocked polyisocyanates include those obtained by adding a blocking agent to the isocyanato groups of the above-mentioned polyisocyanates. Examples of blocking agents include phenol-based agents such as phenol and cresol, aliphatic alcohol-based agents such as methanol and ethanol, active methylene-based agents such as dimethyl malonate and acetylacetone, mercaptan-based agents such as butyl mercaptan and dodecyl mercaptan, acid amide-based agents such as acetanilide and acetic acid amide, lactam-based agents such as ε-caprolactam and δ-valerolactam, acid imide-based agents such as succinimide and maleimide, oxime-based agents such as acetaldoxime, acetoneoxime, and methyl ethyl ketoxime, and amine-based agents such as diphenylaniline, aniline, and ethyleneimine.

Examples of melamine resins include methylol melamines such as dimethylol melamine and trimethylol melamine; alkyl ethers or condensates of these methylol melamines; and condensates of alkyl ethers of methylol melamine.

Examples of polyvalent metal complexes include complexes in which one or more ligands, such as ammonium ions, hydroxide ions, carbonate ions, acetate ions, tartrate ions, or malate ions, are bound to a divalent or higher metal ion, such as calcium, magnesium, zinc, aluminum, titanium, or zirconium.

The content of crosslinking agent (c) is preferably 0.1 to 50 mass% and more preferably 2.0 to 10 mass% based on the total amount of nonvolatile matter in the resin composition.

The resin composition of this embodiment may further contain a weather resistance imparting agent (d), a thixotropy imparting agent (e), a thickener, resins other than the polyurethane resin (a) and the polyurethane resin (a'), other components, etc.

The weather resistance imparting agent (d) may be, for example, at least one selected from the group consisting of hydroxyphenyltriazine derivatives and hindered amine derivatives. By further including weather resistance imparting agent (d) in the resin composition, the cured film can achieve both higher levels of mechanical strength and weather resistance.

Hydroxyphenyltriazine derivatives can improve the weather resistance of cured products by absorbing ultraviolet rays in sunlight. Compared to common benzophenone-type and benzotriazole-type ultraviolet absorbers, hydroxyphenyltriazine derivatives are less likely to bleed out from cured products, allowing the cured product to maintain its weather resistance for long periods of time.

Examples of hydroxyphenyltriazine derivatives include a mixture of 2-[4-(2-hydroxy-3-dodecyloxypropyl)oxy-2-hydroxyphenyl]-4,6-[bis(2,4-dimethylphenyl)-1,3,5-triazine and 2-[4-(2-hydroxy-3-tridecyloxypropyl)oxy-2-hydroxyphenyl]-4,6-[bis(2,4-dimethylphenyl)-1,3,5-triazine (manufactured by BASF Japan Ltd., trade name: TINUVIN 400). ), 2-[4-(octyl-2-methylethanoate)oxy-2-hydroxyphenyl]-4,6-[bis(2,4-dimethylphenyl)]-1,3,5-triazine (manufactured by BASF Japan Ltd., trade name: TINUVIN 479), tris[2,4,6-[2-{4-(octyl-2-methylethanoate)oxy-2-hydroxyphenyl}]-1,3,5-triazine (manufactured by BASF Japan Ltd., trade name: TINUVIN 777), TINUVIN 477, etc. Hydroxyphenyltriazine derivatives are preferably TINUVIN 400 or TINUVIN 477, more preferably TINUVIN 400, as they provide excellent weather resistance to the cured product.

The hindered amine derivative is a 2,2,6,6-tetraalkylpiperidine derivative having a substituent at the 4-position. Examples of the substituent at the 4-position include an alkyl group, an ester group, an alkoxy group, an alkylamino group, and various other substituents. Because the weather resistance of the cured product is improved when the hindered amine derivative is used in combination with a hydroxyphenyltriazine derivative, it is preferable for the hindered amine derivative to have an ester group as the substituent at the 4-position and an alkyl group as the substituent at the N-position. The N-position may also be substituted with an alkyl group, oxy radical, or the like.

Examples of hindered amine derivatives include TINUVIN 292, TINUVIN 123, TINUVIN 144, TINUVIN 765, CHIMASOLV 119FL, CHIMASOLV 2020FDL, CHIMASOLV 944, CHIMASOLV 622LD, etc. (trade names, manufactured by BASF Japan Ltd.); Sumisorb 577, etc. (trade names, manufactured by Sumitomo Chemical Co., Ltd.); Adekastab LA-52, Adekastab LA-5 Examples of suitable hindered amine derivatives include ADK STAB LA-62, ADK STAB LA-67, ADK STAB LA-63P, ADK STAB LA-68LD, ADK STAB LA-82, ADK STAB LA-87, ADK STAB LA-503, and ADK STAB LA-601 (manufactured by ADEKA Corporation, trade names); and SANOL LS-2626, SANOL LS-744, and SANOL LS-440 (manufactured by Sankyo Co., Ltd., trade names). Preferred hindered amine derivatives are TINUVIN 292 and TINUVIN 123, with TINUVIN 123 being more preferred, as they provide excellent weather resistance to the cured product over a long period of time.

The weather resistance additive (d) can also be an aqueous dispersion of at least one selected from the group consisting of hydroxyphenyltriazine derivatives and hindered amine derivatives. Examples of such aqueous dispersions include TINUVIN 123-DW(N), TINUVIN 400-DW(N), TINUVIN 477-DW(N), and TINUVIN 5333-DW(N) (product names, manufactured by BASF Japan Ltd.). The aqueous dispersion is preferably TINUVIN 123-DW(N) or TINUVIN 400-DW(N).

The content of weather resistance imparting agent (d) is preferably 0.01 to 20% by mass, and more preferably 0.05 to 10% by mass, based on the total amount of non-volatile content of the resin composition. When the content of weather resistance imparting agent (d) is 0.01% by mass or more, the weather resistance of the cured product tends to be further improved. When the content of weather resistance imparting agent (d) is 20% by mass or less, bleeding out of weather resistance imparting agent (d) from the cured product can be sufficiently suppressed, and discoloration of the cured product due to the weather resistance imparting agent can tend to be suppressed. Furthermore, when the content of weather resistance imparting agent (d) is within the above range, there tends to be an excellent balance between the effect of imparting weather resistance to the cured product and economic efficiency.

By further including a thixotropic agent (e), the resin composition can maintain coatability with a roller or the like while suppressing sagging when applied to inclined and vertical surfaces. The thixotropic agent (e) may be, for example, finely divided silica. The finely divided silica may be hydrophilic finely divided silica or may have been subjected to a hydrophobic treatment. The hydrophobic treatment can be carried out, for example, by treatment with an alkylsilyl compound. The alkylsilyl compound is preferably dimethylsilyl or trimethylsilyl.

Finely powdered silica can be used in combination with polyhydroxycarboxylic acid ester derivatives, polycarboxylic acid amide derivatives, etc., allowing the amount of finely powdered silica added to be reduced. Examples of polyhydroxycarboxylic acid ester derivatives that can be used include BYK-R 606 (trade name, manufactured by BYK Japan KK). Examples of polycarboxylic acid amide derivatives that can be used include BYK-405 and BYK-R 605 (trade names, manufactured by BYK Japan KK).

The content of the thixotropy-imparting agent (e) is preferably 0 to 20% by mass, based on the total amount of nonvolatile content in the resin composition. Because the acid value of the polyurethane resin (a) is within a predetermined range or the acid value of the nonvolatile content in the resin composition is within a predetermined range, the resin composition of this embodiment can thicken and maintain sufficient viscosity even when the content of the thixotropy-imparting agent (e) is 20% by mass or less. Furthermore, because the content of the thixotropy-imparting agent (e) can be reduced, the transparency of the cured film tends to be improved. The content of the thixotropy-imparting agent (e) is more preferably 1.0 to 15% by mass, and even more preferably 3.0 to 10% by mass, based on the total amount of nonvolatile content in the resin composition.

By including a thickener in the resin composition, the viscosity of the entire resin composition can be increased, thereby preventing sagging when applied to inclined and vertical surfaces. Examples of such thickeners include acrylic thickeners such as polyacrylic acid and acrylic copolymers; urethane associative thickeners; alkali-swellable thickeners; copolymer thickeners such as modified polyoxyethylene-urethane block copolymers; cellulose thickeners such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and hydrophobically modified hydroxycellulose; surfactants such as polyethylene glycol ethers and nonionic surfactants; polysaccharides such as alginates, guar gum, and mannan; and water-soluble resins such as polyvinyl alcohol and polyvinylpyrrolidone. The thickener is preferably a urethane associative thickener.

The content of the thickener is preferably 0 to 20% by mass, more preferably 0.1 to 10% by mass, and even more preferably 0.5 to 2.0% by mass, based on the total amount of non-volatile matter in the resin composition.

Examples of resins other than polyurethane resin (a) and polyurethane resin (a') include acrylic resins, acrylic silicone resins, epoxy resins, alkyd resins, polyolefin resins, and fluororesins. These may be used alone or in combination. The other resins preferably contain one or more hydrophilic groups. Examples of hydrophilic groups include hydroxyl groups, carboxyl groups, sulfonic acid groups, and polyethylene glycol groups. The other resins are preferably at least one selected from the group consisting of polyester resins, acrylic resins, and polyolefin resins.

The acrylic resin is preferably a hydroxyl-containing acrylic resin. Hydroxyl-containing acrylic resins can be produced by copolymerizing a hydroxyl-containing polymerizable unsaturated monomer with another polymerizable unsaturated monomer that is copolymerizable with the hydroxyl-containing polymerizable unsaturated monomer, using known methods such as solution polymerization in an organic solvent or emulsion polymerization in water.

A hydroxyl group-containing polymerizable unsaturated monomer is a compound that has one or more hydroxyl groups and one or more polymerizable unsaturated bonds per molecule. Examples of hydroxyl group-containing polymerizable unsaturated monomers include monoesters of (meth)acrylic acid with dihydric alcohols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; ε-caprolactone-modified products of these monoesters; N-hydroxymethyl (meth)acrylamide; allyl alcohol; and (meth)acrylates having a polyoxyethylene chain with a hydroxyl group at the molecular terminal.

Other polymerizable unsaturated monomers include compounds with polyfunctional polymerizable unsaturated bonds, such as trimethylolpropane triacrylate and divinylbenzene.

The hydroxyl group-containing acrylic resin preferably has an anionic functional group. A hydroxyl group-containing acrylic resin having an anionic functional group can be produced, for example, by using a polymerizable unsaturated monomer having an anionic functional group such as a carboxy group, sulfonic acid group, or phosphate group as one type of polymerizable unsaturated monomer.

From the viewpoints of the storage stability of the resin composition and the water resistance of the cured film, the hydroxyl value of the hydroxyl-containing acrylic resin is preferably 1 to 200 mgKOH/g, more preferably 2 to 100 mgKOH/g, and even more preferably 3 to 60 mgKOH/g.

Furthermore, when the hydroxyl group-containing acrylic resin has an acidic group such as a carboxy group, the acid value of the hydroxyl group-containing acrylic resin is preferably 1 to 200 mgKOH/g, more preferably 2 to 150 mgKOH/g, and even more preferably 5 to 100 mgKOH/g, from the viewpoint of the water resistance of the cured film.

The acrylic silicone resin is not particularly limited, as long as it is, for example, a resin obtained by polymerizing an acrylic silicone monomer together with other polymerizable unsaturated monomers. The acrylic silicone resin is preferably a water-dispersed acrylic silicone resin emulsion.

Examples of epoxy resins include resins obtained by reacting a bisphenol compound with epichlorohydrin. Examples of bisphenol compounds include bisphenol A and bisphenol F.

Examples of alkyd resins include those obtained by reacting polybasic acids such as phthalic acid, terephthalic acid, and succinic acid with polyhydric alcohols and modifiers such as fats and oils, fatty acids (soybean oil, linseed oil, coconut oil, stearic acid, etc.), and natural resins (rosin, amber, etc.).

Examples of polyolefin resins include those obtained by polymerizing or copolymerizing an olefinic monomer with other monomers according to conventional polymerization methods, and then dispersing the resulting polyolefin resin in water using an emulsifier, or those obtained by emulsion polymerizing an olefinic monomer with other monomers. The polyolefin resin may be a chlorinated polyolefin-modified resin.

Examples of olefin-based monomers include α-olefins such as ethylene, propylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-hexene, 1-decene, and 1-dodecene; and conjugated or non-conjugated dienes such as butadiene, ethylidene norbornene, dicyclopentadiene, 1,5-hexadiene, and styrenes. Multiple types of these monomers may be used in combination.

Other monomers copolymerizable with olefin-based monomers include, for example, vinyl acetate, vinyl alcohol, maleic acid, citraconic acid, itaconic acid, maleic anhydride, citraconic anhydride, and itaconic anhydride. Two or more of these monomers may be used in combination.

The fluororesin is not particularly limited, as long as it is, for example, a polymer of a fluorine-containing olefin with other monomers. The fluororesin is preferably a water-dispersible fluororesin emulsion.

The content of resins other than polyurethane resin (a) and polyurethane resin (a') is preferably 0 to 90 mass% and more preferably 0 to 50 mass% based on the total amount of non-volatile components of the resin composition.

Other ingredients that may be used include additives such as film-forming aids, antifoaming agents, wetting and dispersing agents, surfactants, pigments, dyes, inorganic fillers, antioxidants, hardening regulators, metal deactivators, antiozonants, lubricants, anti-termite agents, and anti-fungal agents.

The content of other components is preferably 0 to 90% by mass, and more preferably 0 to 50% by mass, based on the total amount of the resin composition.

The resin composition of this embodiment can be obtained by mixing polyurethane resin (a) (aqueous polyurethane resin dispersion) and crosslinking agent (c), as well as, if necessary, weather resistance imparting agent (d), thixotropy imparting agent (e), resins other than polyurethane resin (a) and polyurethane resin (a'), and other components, using, for example, a disper, ball mill, S.G. mill, roll mill, planetary mixer, etc.

The acid value of the nonvolatile content in the resin composition of this embodiment may be 5 to 17 mgKOH/g (Condition A). When the acid value of the nonvolatile content in the resin composition is 5 mgKOH/g or more, the repulsive force of the emulsion particles can prevent aggregation and precipitation between particles, tending to ensure storage stability. When the acid value of the nonvolatile content in the resin composition is 17 mgKOH/g or less, the re-emulsification or water swelling of the cured product can be suppressed, tending to ensure water resistance. Furthermore, by having the acid value of the nonvolatile content in the resin composition within the above range, sufficient viscosity can be maintained without increasing the content of the thixotropy-imparting agent (d), and sagging resistance can be imparted. Furthermore, since the above effects can be achieved without increasing the content of the thixotropy-imparting agent (d), it tends to be easier to ensure the transparency of the cured product. The acid value of the nonvolatile content in the resin composition is preferably 7 to 17 mgKOH/g, more preferably 10 to 17 mgKOH/g, and even more preferably 13 to 16 mgKOH/g. In this specification, the acid value of the nonvolatile content in a resin composition can be suitably determined by JIS K5601:1999 Acid Value (Titration Method). In this analysis method, the titrant, solvent, etc. can be selected appropriately depending on the components in the resin composition.

The viscosity of the resin composition of this embodiment at 5 rpm may be 0.05 Pa·s or more, 0.1 Pa·s or more, 1.0 Pa·s or more, 6.0 Pa·s or more, or 10 Pa·s or more. When the viscosity of the resin composition is within this range, sagging tends to be less likely to occur when applied by roller or spray. The viscosity of the resin composition at 5 rpm may be 100 Pa·s or less, 60 Pa·s or less, or 30 Pa·s or less. When the viscosity of the resin composition is within this range, stringing and other problems tend to be less likely to occur when applied by roller or spray, and workability tends to be excellent. Note that viscosity refers to the viscosity measured at 23°C using an E-type viscometer with a 3° x R9.7 cone rotor at a rotation speed of 5 rpm in accordance with JIS-Z8803:2011 (Method for measuring viscosity of liquids).

The viscosity of the resin composition of this embodiment at 50 rpm may be 0.01 Pa·s or more, 0.5 Pa·s or more, 1.0 Pa·s or more, or 3.0 Pa·s or more. When the viscosity of the resin composition is within this range, sagging tends to be less likely to occur when applied by roller or spray. The viscosity of the resin composition at 50 rpm may be 50 Pa·s or less, 30 Pa·s or less, or 10 Pa·s or less. When the viscosity of the resin composition is within this range, stringing and other problems tend to be less likely to occur when applied by roller or spray, and workability tends to be excellent. Note that the viscosity at 50 rpm refers to the viscosity measured when the rotation speed at 5 rpm is changed from 5 rpm to 50 rpm.

The thixotropy index (TI) (viscosity at 5 rpm/viscosity at 50 rpm) of the resin composition of this embodiment may be 1.0 or greater, 2.0 or greater, or 3.0 or greater. When the TI of the resin composition is within this range, the resin composition can be more fully imparted with thixotropy (thixotropy), which can better suppress the occurrence of dripping during coating. It also has adequate leveling properties, and when roller coated, no roller pattern remains in the coating film after drying, making it easier to form a smooth coating.

The resin composition of this embodiment is applied and subjected to a sagging test based on ASTM D4400. The coating thickness at which the resin composition does not flow may be 0.75 mm or more, 1.0 mm or more, or 1.5 mm or more. A coating thickness within this range tends to make application to ceilings and vertical surfaces easier.

The tack-free time of the resin composition of this embodiment may be less than 72 hours, less than 24 hours, or less than 6 hours. If the tack-free time is within this range, for example, when a top coat is further applied to a coating formed using the resin composition, the time until the top coat can be applied tends to be shorter. The tack-free time can be measured in accordance with "5.19 Tack-Free Test" in JIS A1439:2010 "Test Methods for Construction Sealant Materials."

When a coating film formed from the resin composition of this embodiment is cured for 7 days under standard conditions of 23°C and 50% RH to form a cured film, the grip elongation at 23°C measured on a 0.3 mm thick cured film may be 150% or more, 200% or more, or 250% or more. When the grip elongation of the cured film is within this range, it tends to have better out-of-plane bending resistance. Grip elongation can be measured in accordance with JIS A 6021:2011.

When a coating film formed from the resin composition of this embodiment is cured for 7 days under standard conditions of 23°C and 50% RH to form a cured film, the total light transmittance measured for the cured film having a thickness of 0.3 mm may be 10% or more, 30% or more, 50% or more, 60% or more, or 80% or more. Total light transmittance can be measured in accordance with JIS K 7375:2008 "Plastics - Determination of total light transmittance and total light reflectance."

When a coating film formed from the resin composition of this embodiment is cured for 7 days under standard conditions of 23°C and 50% RH to form a cured film, the haze measured for the cured film having a thickness of 0.3 mm may be 70% or less, 50% or less, 30% or less, or 20% or less. Haze can be measured in accordance with JIS K 7136:2000 "Determination of haze for plastics - transparent materials."

By simultaneously satisfying that the total light transmittance and haze measured as described above are within the above ranges, the cured film formed from the resin composition of this embodiment has excellent transparency.

<Applications of coating resin compositions for civil engineering and construction>
The resin composition of the present embodiment can be suitably used for preventing tile peeling, waterproofing of buildings, preventing concrete structures from peeling, protecting concrete structures, waterproofing concrete slabs, and the like.

The resin composition for preventing tile peeling is, for example, one that uses the above-mentioned resin composition to prevent tiles from peeling. Because the resin composition for preventing tile peeling uses the above-mentioned resin composition, it is superior in safety during work and ease of application, and can reduce the effects of humidity during application. Furthermore, when using the resin composition for preventing tile peeling, the number of layers required is reduced, preventing the construction period from being extended. Furthermore, the resin composition for preventing tile peeling has excellent weather resistance and can be used to preferably produce a transparent, high-strength cured film.

The resin composition for waterproofing buildings uses, for example, the resin composition described above for waterproofing buildings. Because the resin composition for waterproofing buildings uses the resin composition described above, it offers excellent safety and workability during work and can reduce the effects of humidity during construction. Furthermore, because the resin composition for waterproofing buildings requires a small number of layers, it can prevent the construction period from being extended. Furthermore, the resin composition for waterproofing buildings has excellent weather resistance and can suitably produce a transparent, high-strength cured film. Because the resin composition for waterproofing buildings uses the resin composition described above, it produces a high-strength cured film compared to conventional urethane waterproofing materials. Therefore, when used as a waterproofing material for building roofs, it can improve the durability of the roof and enable the roof to be used for a variety of purposes.

The resin composition for preventing spalling of concrete structures is, for example, one that uses the above-mentioned resin composition to prevent spalling of concrete structures. Because the resin composition for preventing spalling of concrete structures uses the above-mentioned resin composition, it is superior in safety during work and ease of application, and can reduce the impact of humidity during application. Furthermore, when the resin composition for preventing spalling of concrete structures is used, the number of layers required is reduced, which prevents the construction period from being extended compared to when conventional coating resin compositions are used. Furthermore, the resin composition for preventing spalling of concrete structures has excellent weather resistance and strength, and can produce a transparent cured film. The resin composition for preventing spalling of concrete structures can be applied to the surface of a concrete structure to form a cured film that can prevent concrete pieces from spalling due to deterioration of the structure.

The resin composition for preventing spalling of concrete structures has the performance described, for example, in the Push-out Test Method for Surface Coating Materials Applied to Prevent Spalling of Concrete Pieces (JSCE-K 533-2013) of the Japan Society of Civil Engineers, or in the Spalling Prevention Measures of the Structural Construction Management Guidelines (July 2017, East Nippon Expressway Company Limited, Central Nippon Expressway Company Limited, West Nippon Expressway Company Limited).

The resin composition for protecting concrete structures uses, for example, the resin composition described above to protect concrete structures. Because the resin composition for protecting concrete structures uses the resin composition described above, it offers excellent safety and workability during work and can reduce the effects of humidity during construction. Furthermore, when using the resin composition for protecting concrete structures, the number of layers required is reduced, preventing the construction period from being extended. Furthermore, the resin composition for protecting concrete structures can favorably produce a transparent cured film that has excellent weather resistance and strength. The resin composition for protecting concrete structures tends to offer excellent protective performance for concrete structures, such as the appearance of the cured film, adhesion to concrete, and barrier properties against deterioration factors (salt protection, oxygen permeation prevention, water vapor permeation prevention, and carbonation prevention).

The resin composition for waterproofing concrete slabs is, for example, one in which the above-mentioned resin composition is used as a resin composition for waterproofing concrete slabs (e.g., slab waterproofing layer (NEXCO slab waterproofing grade I), slab waterproofing layer (NEXCO slab waterproofing grade II), edge protection material, etc.). Because the resin composition for waterproofing concrete slabs uses the above-mentioned resin composition, it is superior in safety during work and ease of application, and can reduce the effects of humidity during application. Furthermore, because the resin composition for waterproofing concrete slabs requires a small number of layers, it can prevent the construction period from being extended. Because the resin composition for waterproofing concrete slabs uses the above-mentioned resin composition, it is possible to obtain a cured film with excellent weather resistance and high strength.

The resin composition for waterproofing concrete slabs can form a cured film with higher strength than conventional slab waterproofing. Because the resin composition for waterproofing concrete slabs also has excellent weather resistance, when used as a slab waterproofing layer (NEXCO slab waterproofing grade II), the slab waterproofing can be used directly as an edge protection material for the slab waterproofing. Furthermore, by using the resin composition for waterproofing slabs, the slab waterproofing material and edge protection material form a seamless structure, providing a structure with excellent waterproofing reliability.

The resin composition for waterproofing concrete slabs (slab waterproofing layer (NEXCO slab waterproofing grade I), slab waterproofing layer (NEXCO slab waterproofing grade II), edge protection material) meets the performance requirements for slab waterproofing in the Structure Construction Management Guidelines (July 2017, East Nippon Expressway Company Limited, Central Nippon Expressway Company Limited, West Nippon Expressway Company Limited).

<Cured film>
The cured film of one embodiment includes a cured product of the resin composition (a cured product obtained by curing the resin composition). The cured film can also be referred to as a coating film.

The cured film of this embodiment can be obtained, for example, by applying the resin composition to a substrate or the like and curing the resulting coating film for 7 days or more under standard conditions of 23°C and 50% RH. The conditions for preparing the cured film when measuring its physical properties may be, for example, the preparation conditions described in the Examples.

The thickness of the cured film in this embodiment may be 0.1 mm or more, 0.2 mm or more, or 0.3 mm or more, and may be 5.0 mm or less, 3.0 mm or less, or 2.0 mm or less. When the thickness of the cured film is within this range, the peeling prevention effect tends to be more sufficient.

The cured film of this embodiment may be slightly colored or slightly cloudy, but preferably has excellent transparency. The haze of the cured film of this embodiment, measured at a film thickness of 0.3 mm, may be 70% or less, 50% or less, 30% or less, or 20% or less. The haze value of the cured film can also be adjusted with additives, etc., as appropriate, to improve appearance, such as glare. Haze can be measured in accordance with JIS K 7136:2000, "Determination of haze for plastics - transparent materials."

In the cured film of this embodiment, the total light transmittance measured at a film thickness of 0.3 mm may be 10% or more, 30% or more, 50% or more, 60% or more, or 80% or more. When the total light transmittance of the cured film is within this range, abnormalities such as cracks beneath the cured film tend to be easily visible even after the cured film has been formed. Total light transmittance can be measured in accordance with JIS K 7375:2008 "Plastics - Determination of total light transmittance and total light reflectance."

The grip elongation of the cured film of this embodiment, measured at 23°C with a film thickness of 0.3 mm, may be 150% or more, 200% or more, or 250% or more. When the grip elongation of the cured film is within this range, it tends to have better out-of-plane bending resistance. In this specification, grip elongation can be measured in accordance with JIS A 6021:2011.

The gage length elongation of the cured film of this embodiment, measured at 23°C with a film thickness of 0.3 mm, may be 150% or more, 200% or more, or 250% or more. When the gage length elongation of the cured film at 23°C is within this range, the film tends to have better out-of-plane bending resistance. The grip elongation can be measured in accordance with JIS A 6021:2011.

The breaking stress of the cured film of this embodiment, measured at 23°C with a film thickness of 0.3 mm, may be 15 MPa or more, 25 MPa or more, 30 MPa or more, or 40 MPa or more. When the breaking stress of the cured film is within this range, it tends to have better out-of-plane bending resistance. The breaking stress can be measured in accordance with JIS A 6021:2011.

The cured film of this embodiment may have a tensile modulus of elasticity at 23°C measured at a film thickness of 0.3 mm of 1 to 500 MPa, preferably 10 to 300 MPa, and more preferably 50 to 250 MPa. The tensile modulus of elasticity can be measured in accordance with JIS A 6021:2011.

In the cured film of this embodiment, the loss tangent (tan δ) measured by dynamic viscoelasticity measurement does not need to have a maximum value in the temperature range of -10 to 30°C. By not having a maximum value for the loss tangent within this temperature range, the changes in the breaking stress and gauge length elongation within the above temperature range (the temperature range where the loss tangent does not have a maximum value) are small, resulting in excellent toughness and load-bearing capacity reliability even in environments such as cold and hot climates. Dynamic viscoelasticity measurement can be performed using the method described in the Examples. The maximum value for the loss tangent can be determined from a graph showing the temperature dependence of the ratio of the loss modulus (E") to the storage modulus (E') measured by dynamic viscoelasticity measurement (the value obtained by dividing the loss modulus by the storage modulus: E"/E').

The cured film of this embodiment may have a breaking stress retention rate of 60% or more, 80% or more, or 90% or more before and after an accelerated exposure test. The cured film may have a gauge length elongation retention rate of 60% or more, 80% or more, or 90% or more before and after an accelerated exposure test. The accelerated exposure test is a weather resistance test conducted using a sunshine weatherometer as specified in JIS B 7753:2007 for a test time of 2,500 hours.

The color difference (ΔE) of the cured film after an accelerated exposure test may be 15 or less, 5 or less, or 3 or less. The color difference can be determined by measuring test pieces before and after the accelerated exposure test in accordance with JIS K5600-4-6:1999 "Colorimetry (SCE) for General Test Methods for Paints."

The gloss retention of the cured film before and after the accelerated exposure test may be 60% or more, or 80% or more. The gloss retention can be determined by measuring the test piece before and after the accelerated exposure test in accordance with JIS K5600-4-7:1999 "Specular Gloss (60°) - General Test Methods for Paints."

Regarding the flexibility (crack-following ability) of the cured film, the elongation of the cured film may be 3 mm or more, 10 mm or more, or 20 mm or more. The above-mentioned concrete surface protection performance is required in accordance with the concrete surface protection performance verification of the Structure Construction Management Guidelines (July 2017, East Nippon Expressway Company Limited, Central Nippon Expressway Company Limited, West Nippon Expressway Company Limited).

<Coating method for civil engineering and architectural structures>
A coating method for a civil engineering or architectural structure according to one embodiment includes a step of applying the resin composition to the civil engineering or architectural structure. The coating method of this embodiment may include, for example, a step of applying the resin composition to the target civil engineering or architectural structure to form a coating film (resin layer) and a step of curing the coating film to form a cured film (cured product layer). The coating method of this embodiment may also include, for example, a step of applying at least one selected from the group consisting of a primer, a leveling agent, a gas barrier paint, a reinforcing paint, and a putty to the surface of the civil engineering or architectural structure before applying the resin composition to the civil engineering or architectural structure. The coating method of this embodiment may also include a step of applying a reinforcing mesh or staple fibers (e.g., a step of impregnating the mesh or staple fibers with the resin composition). The term "civil engineering or architectural structure" refers to, for example, civil engineering structures such as bridges, elevated roads, dams, tunnels, roads, and land developments; buildings such as buildings, condominiums, and houses.

Methods for applying the above-mentioned resin composition to civil engineering and architectural structures (e.g., methods for forming a coating film) include, for example, painting and coating. Because the above-mentioned resin composition has a sufficiently long pot life, it can also be applied manually using a spray, trowel, spatula, brush, roller, etc. By applying the resin composition manually, a coating film of the desired thickness can be formed outdoors.

The unevenness control agent and putty are preferably used when the surface of a civil engineering or architectural structure is uneven. Applying the unevenness control agent and putty to the surface of the civil engineering or architectural structure makes it easier to apply the resin composition. The unevenness control agent may be applied after applying a primer to the surface of the concrete structure.

In the coating method of this embodiment, the thickness of the coating film can be adjusted depending on the thickness after curing (thickness of the cured film (cured product layer)), and may be, for example, 0.1 mm or more, 0.2 mm or more, or 0.3 mm or more, and 5.0 mm or less, 3.0 mm or less, or 2.0 mm or less. When the coating film thickness is within this range, it tends to be more effective in preventing peeling. In the coating method of this embodiment, the resin composition may be applied in multiple applications.

In the coating method of this embodiment, a resin layer made of a primer may be provided as a first layer to enhance adhesion between the cured film (cured product layer) and the surface of the civil engineering or architectural structure. The resin constituting the first resin layer may be, for example, an acrylic resin, a urethane resin, an epoxy resin, or a vinyl acetate resin. From the standpoints of odor and environmental impact, the primer is preferably a solvent-free or water-based material. The primer is also preferably a one-component material. The thickness of the first layer can be adjusted depending on the thickness of the cured film (cured product layer). For example, it may be 0.01 mm or more, 0.05 mm or more, or 0.1 mm or more, and may be 1.0 mm or less, 0.5 mm or less, or 0.3 mm or less. A thickness of the first layer within this range tends to provide excellent adhesion and suppress the occurrence of blistering. The primer may be applied in multiple applications to form the first layer.

In the coating method of this embodiment, after forming the cured film (cured product layer), a resin layer made of a topcoat material may be applied as a third layer. By applying a resin layer made of a topcoat material, the strength of the cured film (cured product layer) can be further increased. The resin constituting the resin layer serving as the third layer may be, for example, a urethane resin, a fluororesin, or an acrylic silicone resin. From the standpoints of odor and environmental impact, the topcoat material is preferably a solvent-free or water-based material. Furthermore, the topcoat material is preferably a one-component material. The thickness of the third layer can be adjusted depending on the thickness of the cured film (cured product layer). For example, it may be 0.01 mm or more, 0.05 mm or more, or 0.1 mm or more, and may be 1.0 mm or less, 0.5 mm or less, or 0.3 mm or less. A thickness of the third layer within this range tends to provide excellent weather resistance and maintain aesthetic appearance for a long period of time. The topcoat material may be applied in multiple coats to form the third layer.

<How to prevent tiles from falling off>
In one embodiment, a method for preventing tile peeling includes fixing an existing tiled exterior wall surface with metal anchors and covering the exterior wall surface with a coating layer, the coating layer including a layer containing a cured product of the resin composition.

An existing tiled exterior wall refers to an exterior wall that has a laminated finish in which inorganic tiles with low water absorption and excellent durability are attached to a concrete frame using cement mortar or the like, with joints formed. Examples of tiles include porcelain tiles and stoneware tiles. Porcelain tiles are preferred.

The method for fixing the exterior wall surface with metal anchors is not particularly limited, and existing construction methods can be applied. The anchors are preferably drilled into the center of the tile and driven in to secure the tile to the frame, but they can also be driven into the joints. Furthermore, it is preferable to insert the anchors so that their tips reach the frame by 20 mm or more. Taking into account the mass of the existing tiled exterior wall, it is preferable to drive four or more anchors per square meter (1 ^m2 ). It is preferable to use anchors with injection ports, and after driving, inject a reactive curing resin such as epoxy resin to reinforce the interior of the frame with resin. It is preferable that the anchors be able to withstand pull-out forces from the frame by, for example, expanding their tips after driving. One suitable example of an anchor is one with a slit formed from the axial midpoint of the hollow shaft of the anchor to the tip and a built-in extension, which can be further driven with a metal rod or the like after driving the anchor in to expand the tip and drive it into the frame.

The method for covering the exterior wall surface with a coating layer can be the same as the coating method (applying method) for civil engineering and architectural structures described above.

<Structure>
In one embodiment, the structure comprises an exterior wall structure including tiles and a coating layer disposed on the exterior wall structure.

One embodiment of the coating layer includes a layer containing a cured product of the resin composition described above. Another embodiment of the coating layer includes a first layer and a second layer, in this order from the exterior wall structure. Here, the first layer is a resin layer of any of acrylic resin, acrylic styrene resin, urethane resin, epoxy resin, and vinyl acetate resin. The second layer is a layer containing a cured product of the resin composition described above. In this embodiment, the coating layer may further include a third layer, which is a resin layer of any of urethane resin, fluororesin, and acrylic silicone resin, on the second layer opposite to the first layer. Another embodiment of the coating layer includes a second layer and a third layer, in this order from the exterior wall structure.

Examples of resins that make up the resin layer as the first layer include those similar to the resins that make up the resin layer as the first layer in the coating method (applying method) for civil engineering and architectural structures. Examples of resins that make up the resin layer as the third layer include those similar to the resins that make up the resin layer as the third layer in the coating method (applying method) for civil engineering and architectural structures.

The structure of this embodiment may further include metal anchors that hold the tiles and/or coating layers included in the exterior wall structure.

The present invention will be explained in more detail below using examples. However, the present invention is not limited to these examples.

<Evaluation method>
(Characteristics of Resin Composition)
[Measurement of non-volatile content]
The resin composition was mixed until homogeneous and then measured according to JIS K5601-1-2: 2008. In this measurement, the heating temperature was 140°C and the heating time was 180 minutes.

[Measurement of acid value]
The resin composition was mixed until homogeneous and then measured for acid value (titration method) according to JIS K5601:1999 using an automatic titrator COM-1600 manufactured by HIRANUMA Co., Ltd. In this measurement, 3.0 g of the resin composition was thoroughly dispersed in 10 mL of pure water, and then 50 mL of ethanol was added to prepare a titration solution.

[Viscosity measurement]
The resin composition was mixed until homogeneous, and the viscosity was measured according to JIS-Z8803:2011 (Method for measuring viscosity of liquids) using an E-type viscometer TVE25H manufactured by Toki Sangyo Co., Ltd. A 3° x R9.7 cone rotor was used, and the sample volume was 0.2 mL. The measurement temperature was 23°C. The viscosity was measured at rotation speeds of 5 rpm and 50 rpm, and the thixotropy index (TI) was calculated by dividing the viscosity at a rotation speed of 5 rpm by the viscosity at a rotation speed of 50 rpm.

[Measurement of sagging resistance]
Based on the method described in ASTM D4400, under conditions of 23 ° C, a glass plate (thickness: 4 mm × width: 200 mm × length: 200 mm) was placed on a horizontal table, and the resin composition was spread into the groove of a metal sag tester (manufactured by BYK ASTM ASM-3) and slid while pressing the sag tester against the glass, and the resin composition was coated in parallel bands of different thicknesses. Thereafter, the glass plate was immediately held vertically with the thicker band facing downwards so that the trajectory line of the sag tester was horizontal for 8 hours, and the state of flow of the resin composition was examined. The presence or absence of paint flow into the width of the trajectory line was confirmed, and the largest band where the resin composition did not flow was determined. The coating thickness of the resin composition of this largest band was evaluated according to the following criteria. A large coating thickness of the resin composition means that there is little (or no) sagging even when the resin composition is applied thickly.
A: The coating thickness of the resin composition was 1.5 mm or more.
B: The coating thickness of the resin composition was 1.0 mm or more and less than 1.5 mm.
C: The coating thickness of the resin composition was 0.75 mm or more and less than 1.0 mm.
D: The coating thickness of the resin composition was less than 0.75 mm.

(Characteristics of the cured film)
[Preparation of cured film]
The resin composition was mixed until homogeneous, and applied to a release-treated substrate at a rate of 0.3 kg/ ^m² per application. After drying at room temperature (23°C) and confirming that there was no tack, the same amount was applied again. After applying three times in total, the composition was cured for seven days under standard conditions of 23°C and 50% RH to produce a cured film as an evaluation sample. The film thickness of the cured film was 0.3 mm.

[Preparation of multilayer cured film]
The resin composition was mixed until homogeneous, and applied to a release-treated substrate at 0.3 kg/ ^m² per application. After drying at room temperature (23°C) to confirm that there was no tack, the same amount was applied again. After applying a total of three times, the coating was dried at room temperature (23°C) to confirm that there was no tack, and then topcoat material 1 (water-based fluororesin 1) or topcoat material 2 (water-based fluororesin 2) was applied at 0.1 kg/ ^m² per application. After drying at room temperature (23°C) to confirm that there was no tack, the same amount was applied again. A cured film, which was an evaluation sample, was prepared by aging for 7 days under standard conditions of 23°C and 50% RH.

[Tensile test (grip elongation, gauge elongation, breaking stress, and tensile modulus)]
Test specimens were punched out from the cured films obtained above using a No. 3 dumbbell punch, and the grip elongation, gauge elongation, breaking stress, and tensile modulus of the obtained test specimens were measured in accordance with JIS A 6021:2011.

[Water resistance (water whitening resistance, water swelling rate, and elution rate)]
The cured film obtained above was cut into a size of 25 x 25 mm, and the initial mass W0 (mg) was measured. After immersion in hot water at 60°C for 24 hours, moisture on both sides of the cured film was wiped off with a Kimtowel, and the water whitening resistance (appearance) of the cured film was evaluated and the wet mass Wt (mg) of the cured film was measured. The wet mass Wt (mg) was then measured. The cured film was then force-dried at 100°C for 3 hours, and the dry mass Wd (mg) was measured. Note that all masses were measured to the first decimal place.

The appearance was observed, and the water whitening resistance was evaluated according to the following criteria.
A: No change in appearance.
B: Whitened, but when the cured film was placed on a Kimtowel, the pattern was visible.
C: Significant whitening occurred, and the pattern underneath the cured film was not visible.

The water swelling ratio was calculated using the following formula (C).
Water swelling rate (mass%) = (Wt-W0)/W0 (formula (C))

The dissolution rate was calculated by the following formula (D).
Elution rate (mass%) = (W0-Wd)/W0 (formula (D))

[Haze Measurement]
The haze of the cured film obtained above was measured using NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K 7136:2000 (Method of determining haze of plastic transparent materials).

[Measurement of total light transmittance]
The total light transmittance of the cured film obtained above was measured using NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K 7136:2000 (Plastics - Determination of total light transmittance and total light reflectance).

[Weather resistance (elongation retention rate and stress retention rate)]
Test pieces measuring 150 mm long x 70 mm wide x 0.3 mm thick were taken from the cured films obtained above and subjected to an accelerated exposure test using the xenon lamp method, Method 1, Cycle A, specified in JIS K 5600-7-7: 2008. The test pieces were then aged for 3 days under standard conditions of 25°C and 50% RH, and then subjected to tensile tests (gauge line elongation and breaking stress), which were compared with the tensile properties before the accelerated exposure test.

(Structure characteristics)
[Crack followability]
The crack follow-up ability was evaluated according to the method specified in JSCE-K 532-2013. The test specimens were prepared according to the following procedure.
A substrate was prepared using the method specified in Regulation 4.3, and a one-component water-based primer (primer 1 (acrylic styrene resin)) was applied at an amount of 0.1 kg/ ^m² , leaving 30 mm on both ends, and then dried at room temperature for 3 hours to obtain a resin layer (first layer). The resin composition was then applied at 0.3 kg/ ^m² per application, dried at room temperature (23°C), and after confirming that there was no tack, the same amount was applied again. The resin composition was applied a total of three times, and then cured for 7 days under standard conditions of 23°C and 50% RH to obtain a layer (second layer) containing the cured product of the resin composition, which was the evaluation sample. Each evaluation sample was evaluated three times and judged as follows:
A: In all three tests, the cured film did not break even at a displacement of 20 mm.
B: In two out of three tests, the cured film did not break at a displacement of 20 mm.
C: In one out of three tests, the cured film did not break at a displacement of 20 mm.
D: In all three tests, the cured film broke at a displacement of less than 20 mm.

[Weather resistance (elongation retention rate and stress retention rate)]
Test pieces measuring 150 mm long x 70 mm wide x 0.3 mm thick were taken from the cured film obtained in the above [Preparation of multilayer cured film] and subjected to an accelerated exposure test using the xenon lamp method, Method 1, Cycle A, specified in JIS K 5600-7-7: 2008. Thereafter, the test pieces were aged for 3 days under standard conditions of 25°C and 50% RH, and then subjected to tensile tests (gauge line elongation and breaking stress), and the tensile properties were compared with those before the accelerated exposure test.

[Repeated hot and cold performance]
The study was conducted in accordance with the Urban Renaissance Agency's "Common Specifications for Maintenance Works: Collection of Registrations for Quality Assessment Standards for Equipment and Construction Methods, 2017 Edition." Specifically, a 0.1 kg/m² application of a one-component water-based primer (primer 1 (acrylic styrene resin)) was applied to a mortar board (300 mm wide x 300 mm long x ⁵⁰ mm thick) with 45-layer glazed ceramic tiles and to an unapplied mortar board. The primer was then dried at room temperature for three hours to obtain a resin layer (first layer). Each resin composition was then applied at a rate of 0.3 kg/ ^m² per application. After drying at room temperature (23°C) to confirm the absence of tackiness, the same amount was applied again. Each resin composition was applied a total of three times to obtain a layer containing the resin composition. Thereafter, a one-component water-based topcoat material (Topcoat material 1 (water-based fluororesin 1)) was applied at a coating amount of 0.08 kg/ ^m² , dried at room temperature, and after confirming that there was no tack, the same amount was applied again to obtain a resin layer (third layer). The sample was then cured for 7 days under standard conditions of 23°C and 50% RH to harden the resin composition, forming a layer (second layer) containing the cured resin composition, thereby obtaining an evaluation sample. After 3 days of curing, the sides were sealed with epoxy resin (E250, manufactured by Konishi Co., Ltd.).

The evaluation samples prepared as described above were immersed in water at room temperature (23°C) for 16 hours and then dried in a dryer at 80°C for 8 hours. This cycle was repeated 10 times, after which the samples were attached to a 40mm x 40mm metal attachment with epoxy resin (Konishi Co., Ltd., E250), and incisions were made around the edges that reached the substrate. The tensile adhesive strength was measured using a hydraulic tensile tester. Tests were performed at three locations in the center of the specimen and three locations at the end of the specimen (approximately 10mm from the edge), and the average value was calculated.

[Out-of-plane bending performance]
The test was conducted in accordance with the Urban Renaissance Agency's "Conservation Work Common Specifications: Collection of Registrations for Quality Assessment Standards for Equipment and Construction Methods, 2017 Edition." Specifically, a mortar board (100 mm wide x 600 mm long x 30 mm thick) was split in half at the longitudinal center, and the fractured surfaces were butted together. A one-component water-based primer (primer 1 (acrylic styrene resin)) was applied to the upper surface of the formwork face at a rate of 0.1 kg/ ^m² and dried at room temperature for 3 hours to obtain a resin layer (first layer). Each resin composition was then applied at a rate of 0.3 kg/ ^m² per application, and after drying at room temperature to confirm the absence of tackiness, the same amount was applied again. Each resin composition was applied a total of three times to obtain a layer containing the resin composition. Thereafter, a one-component water-based topcoat material (Topcoat material 1 (water-based fluororesin 1)) was applied in an amount of 0.08 kg/ ^m² , and after drying at room temperature to confirm that there was no tack, the same amount was applied again to obtain a resin layer (third layer). Next, the sample was cured for 7 days under standard conditions of 23°C and 50% RH to harden the resin composition, and a layer (second layer) containing the cured resin composition was formed to obtain an evaluation sample. Next, a four-point bending test was performed by loading the bottom of the evaluation sample at a rate of 5 mm/min. The sample was displaced up to 40 mm and the presence or absence of rupture in the cured film was confirmed.

<Synthesis of aqueous polyurethane resin dispersion>
(Synthesis Example 1)
In a reaction vessel equipped with a stirrer and a heater, 2000 g (1.00 mol) of ETERNACOLL UH-200 (registered trademark; polycarbonate diol manufactured by Ube Industries, Ltd.; number average molecular weight 2000; hydroxyl value 56.1 mgKOH/g; polycarbonate diol obtained by reacting 1,6-hexanediol with a carbonate ester), 553.8 g (2.49 mol) of isophorone diisocyanate, and 104.6 g (0.780 mol) of 2,2-dimethylolpropionic acid were heated in 936 g of dipropylene glycol dimethyl ether in the presence of a catalyst under a nitrogen atmosphere at 80 to 90°C for 5 hours. The isocyanato group content at the end of the urethanization reaction was 1.71% by mass. After the reaction mixture was heated to 80°C, 74.1 g of triethylamine was added and the mixture was stirred for 30 minutes. The reaction mixture was withdrawn and added to 5367 g of water with vigorous stirring, and then 74.5 g of 2-methyl-1,5-pentanediamine was added as a chain extender to obtain an aqueous polyurethane resin dispersion (PUD) P1.

(Synthesis Examples 2 to 4)
Aqueous polyurethane resin dispersions (PUD) P2 to P4 were synthesized in the same manner as in Synthesis Example 1, except that the raw materials and charging ratios (mass ratios) shown in Table 1 were changed. In particular, the charging ratios of the acidic group-containing polyol and water were adjusted so that the acid value and nonvolatile content concentration would be the calculated values shown in Table 1. P4 was synthesized by synthesizing an aqueous polyurethane resin dispersion using the method described in JP 2019-035240 A, and then distilling off methyl ethyl ketone under reduced pressure.

The materials used in Table 1 are as follows:
UH-200: Polycarbonate diol (manufactured by Ube Industries, Ltd., product name: ETERNACOLL UH-200, hydroxyl value: 56.1 mg KOH/g)
UH-100: Polycarbonate diol (manufactured by Ube Industries, Ltd., product name: ETERNACOLL UH-100, hydroxyl value: 112.2 mg KOH/g)
C-2090: Polycarbonate diol (manufactured by Kuraray Co., Ltd., product name: Kuraray Polyol C-2090, hydroxyl value: 56.1 mgKOH/g)
BDL: 1,4-butanediol, IPDI: isophorone diisocyanate, HMDI: dicyclohexylmethane-4,4'-diisocyanate, DMPA: 2,2-dimethylolpropionic acid, DMBA: 2,2-bis(hydroxymethyl)butyric acid, MPMD: 2-methyl-1,5-pentanediamine, IPDA: isophorone diamine, TEA: triethylamine, DMM: dipropylene glycol dimethyl ether, NEP: N-ethylpyrrolidone, MEK: methyl ethyl ketone

(Examples 1, 2A, 2B and Comparative Examples 1A, 1B, 2A, 2B, 3)
The components of the formulation in the mass (g) shown in the "Formulation" section of Table 2 were mixed until uniform, to obtain resin compositions of Examples 1, 2A, and 2B and Comparative Examples 1A, 1B, 2A, 2B, and 3. Using these resin compositions, the physical properties of the resin compositions, the cured films, and the structures were evaluated using the evaluation methods described above. The results are shown in Tables 2 and 3.

(Examples 3 and 4)
Using the resin composition obtained in Example 1 and the topcoat material 1 listed in Table 4, a layer containing a cured product of the resin composition was obtained by the method described above in [Weather resistance (elongation retention and stress retention)]. Using the resin composition obtained in Example 1 and the topcoat material 2 listed in Table 4, a layer containing a cured product of the resin composition was obtained by the method described above in [Weather resistance (elongation retention and stress retention)]. Using these structures, the above [Weather resistance (elongation retention and stress retention)] was evaluated. The results are shown in Table 4.

(Examples 5 and 6)
Using the resin composition obtained in Example 1 and the primer material 1 listed in Table 4, a layer containing a cured product of the resin composition was obtained by the methods described above in [Hot/Cool Cycling Performance] and [Out-of-Plane Bending Performance]. Using the resin composition obtained in Example 1, the topcoat material 1 listed in Table 3, and the primer material 1 listed in Table 3, a layer containing a cured product of the resin composition was obtained by the methods described above in [Hot/Cool Cycling Performance] and [Out-of-Plane Bending Performance]. Using these structures, the above-mentioned [Hot/Cool Cycling Performance] and [Out-of-Plane Bending Performance] were evaluated. The results are shown in Table 4.

The materials used in Table 2 are as follows:
Carbodilite E-05: a compound having a carbodiimide group (manufactured by Nisshinbo Chemical Inc., NCN equivalent 310, emulsion type, active ingredient concentration 40% by mass)
Carbodilite V-02: a compound having a carbodiimide group (manufactured by Nisshinbo Chemical Inc., NCN equivalent 590, water-soluble type, active ingredient concentration 40% by mass)
Baycoat 20: Polyvalent metal complex (zirconium ammonium carbonate aqueous solution) (manufactured by Nippon Light Metal Co., Ltd., 20% by mass in terms of zirconium oxide)
Tinuvin-400DW(N): Water-dispersible UV absorber (manufactured by BASF Japan Ltd., active ingredient concentration 40% by mass)
Tinuvin-123DW(N): Water-dispersible HALS (manufactured by BASF Japan Ltd., active ingredient concentration 30% by mass)
Aerosil R974: fumed silica (manufactured by Nippon Aerosil Co., Ltd., specific surface area 200 m ² /g, dimethylsilyl treated)
Adekanol UH-756VF: urethane associative thickener (manufactured by ADEKA Corporation, active ingredient concentration 32% by mass)
Ester compound: 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate BYK-093: Silicone-based defoamer (manufactured by BYK Chemie)

The materials used in Table 4 are as follows:
Primer 1: Acrylic styrene resin Top coat 1: Water-based fluororesin 1 (medium gloss, 60° Gloss value of multi-layer cured film: 41)
Topcoat 2: Water-based fluororesin 2 (low gloss multi-layer cured film 60 ° Gloss value 68)

As shown in Table 2, the civil engineering and construction coating resin compositions of Examples 1 and 2 had better application properties than the civil engineering and construction coating resin compositions of Comparative Examples 1 to 3. Furthermore, the cured products had good elongation and therefore excellent crack followability. As shown in Table 3, they also had excellent water resistance and transparency. These results confirm that the civil engineering and construction coating resin composition of the present invention has good application properties and is capable of forming cured products with good transparency and water whitening resistance.

Claims (21)

A coating resin composition for civil engineering and construction, comprising (a) a polyurethane resin having a polycarbonate structure, (b) an aqueous medium, and (c) a crosslinking agent reactive with an acidic group or a salt thereof,
A coating resin composition for civil engineering and construction, which satisfies at least condition A of the following conditions A and B:
Condition A: The acid value of the nonvolatile matter in the coating resin composition for civil engineering and construction is 5 to 17 mgKOH/g.
Condition B: The acid value of the polyurethane resin (a) having a polycarbonate structure is 5 to 22 mgKOH/g. The coating resin composition for civil engineering and construction described in claim 1 satisfies both condition A and condition B. The coating resin composition for civil engineering and construction according to claim 1 or 2, wherein the polyurethane resin (a) having a polycarbonate structure has an acidic group. The coating resin composition for civil engineering and construction according to any one of claims 1 to 3, wherein the polyurethane resin (a) having a polycarbonate structure has a structure derived from a linear aliphatic diol within the polycarbonate structure of the polyurethane resin. The coating resin composition for civil engineering and construction according to any one of claims 1 to 4, wherein the polyurethane resin (a) having a polycarbonate structure has a structure derived from an aliphatic polyisocyanate in the polyurethane resin. The coating resin composition for civil engineering and construction according to any one of claims 1 to 5, wherein the crosslinking agent (c) reactive with an acidic group or a salt thereof includes a compound having a carbodiimide group. Further comprising a thixotropic agent (e),
7. The coating resin composition for civil engineering and construction according to claim 1, wherein the content of the thixotropy-imparting agent (e) is 20 mass% or less, based on the total amount of non-volatile components of the coating resin composition for civil engineering and construction. The coating resin composition for civil engineering and construction according to any one of claims 1 to 7, wherein the viscosity of the coating resin composition for civil engineering and construction measured in accordance with JIS-Z8803:2011 (Method for measuring viscosity of liquids) using an E-type viscometer with a 3° x R9.7 cone rotor at a rotation speed of 5 rpm and at 23°C is 6.0 to 60 Pa·s. The coating resin composition for civil engineering and construction according to any one of claims 1 to 8, wherein the coating resin composition for civil engineering and construction is applied and subjected to a sagging test in accordance with ASTM D4400, and the coating thickness of the coating resin composition for civil engineering and construction without any run-in is 0.75 mm or more. The coating resin composition for civil engineering and construction according to any one of claims 1 to 9, wherein when a coating film formed from the coating resin composition for civil engineering and construction is cured for 7 days under standard conditions of 23°C and 50% RH to form a cured film, the grip elongation at 23°C, measured on a cured film having a thickness of 0.3 mm according to JIS A 6021:2011, is 150% or more. The coating resin composition for civil engineering and construction according to any one of claims 1 to 10, wherein a coating film formed from the coating resin composition for civil engineering and construction is cured for 7 days under standard conditions of 23°C and 50% RH to form a cured film, and the total light transmittance measured for a cured film having a thickness of 0.3 mm is 10% or more. The coating resin composition for civil engineering and construction according to any one of claims 1 to 11, which is used to prevent tile peeling, waterproof buildings, prevent concrete structure peeling, protect concrete structures, or waterproof concrete decks. A cured film comprising a cured product of the coating resin composition for civil engineering and construction use described in any one of claims 1 to 11. A method for coating a civil engineering or architectural structure, comprising the step of applying the coating resin composition for civil engineering or architectural structures described in any one of claims 1 to 11 to the civil engineering or architectural structure. The method includes a step of fixing an existing tiled exterior wall surface with metal anchors and covering the exterior wall surface with a coating layer,
A method for preventing tile peeling, wherein the coating layer comprises a layer containing a cured product of the coating resin composition for civil engineering and construction use according to any one of claims 1 to 11. A method for coating a civil engineering and architectural structure, comprising a step of applying to the civil engineering and architectural structure a coating resin composition for civil engineering and architectural use, the coating resin composition comprising (a) a polyurethane resin having a polycarbonate structure, (b) an aqueous medium, and (c) a crosslinking agent reactive with an acidic group or a salt thereof, and satisfying at least one of the following conditions A and B:
Condition A: The acid value of the nonvolatile matter in the coating resin composition for civil engineering and construction is 5 to 17 mgKOH/g.
Condition B: The acid value of the polyurethane resin (a) having a polycarbonate structure is 5 to 22 mgKOH/g. The method includes a step of fixing an existing tiled exterior wall surface with metal anchors and covering the exterior wall surface with a coating layer,
The method for preventing tile peeling, wherein the coating layer contains a layer containing a cured product of a coating resin composition for civil engineering and construction, which comprises (a) a polyurethane resin having a polycarbonate structure, (b) an aqueous medium, and (c) a crosslinking agent reactive with an acidic group or a salt thereof, and satisfies at least one of the following conditions A and B:
Condition A: The acid value of the nonvolatile matter in the coating resin composition for civil engineering and construction is 5 to 17 mgKOH/g.
Condition B: The acid value of the polyurethane resin (a) having a polycarbonate structure is 5 to 22 mgKOH/g. An exterior wall structure including tiles, and a coating layer provided on the exterior wall structure,
A structure, wherein the coating layer comprises a layer containing a cured product of the coating resin composition for civil engineering and construction use according to any one of claims 1 to 11. A structure comprising an exterior wall structure including tiles and a coating layer provided on the exterior wall structure,
the coating layer includes a first layer and a second layer in this order from the outer wall structure,
the first layer is a resin layer selected from the group consisting of an acrylic resin, an acrylic-styrene resin, a urethane resin, an epoxy resin, and a vinyl acetate resin;
A structure, wherein the second layer is a layer comprising a cured product of the coating resin composition for civil engineering and construction use according to any one of claims 1 to 11. 20. The structure according to claim 19 , wherein the coating layer further comprises a third layer of a resin layer selected from a urethane resin, a fluororesin, and an acrylic silicone resin, on the second layer and on the opposite side to the first layer. 21. The structure of claim 19 or 20 , further comprising metal anchors that hold the tiles and/or the coating layer included in the exterior wall structure.