JP7498621B2 - Polyisocyanate composition, coating composition and coated substrate - Google Patents

Description

The present invention relates to a polyisocyanate composition, a coating composition, and a coating substrate.

Two-component polyurethane coating compositions are room temperature curable, and the resulting coating films have excellent abrasion resistance, chemical resistance, and stain resistance. In recent years, in consideration of environmental conservation, there has been a demand for water-based room temperature crosslinking two-component urethane coating compositions that have been conventionally used as solvent-based coatings.
Polyisocyanates modified with anions to impart hydrophilicity have the characteristic of being easily dispersible in water and are increasingly being accepted in many fields. Many methods for producing such water-dispersible polyisocyanates have been reported so far.

For example, Patent Document 1 discloses a reaction product of a polyisocyanate compound and a compound having at least one sulfonic acid group and an isocyanate group.
Patent Documents 2 and 3 disclose polyisocyanate compositions containing modified polyisocyanates obtained by reacting an amine salt of a sulfonic acid having a hydroxyl group with a polyisocyanate.
Patent Documents 4 and 5 disclose modified polyisocyanates obtained by reacting aminosulfonic acids having specific structures with polyisocyanates.

Japanese Patent Application Laid-Open No. 8-176267 JP 2015-205957 A JP 2016-017157 A Japanese Patent No. 4806511 International Publication No. 2015/035673

Water-based two-component urethane coating compositions are used to paint furniture and building materials, residential woodwork, wooden floors in residential and school facilities, trains and construction machinery, agricultural vehicles, etc. There is a demand for polyisocyanate compositions that can produce coating films with excellent appearance, hardness, water resistance, and stain resistance.

With the polyisocyanate composition described in Patent Document 1, it is difficult to achieve both excellent pot life and dispersibility when dispersed in water or a base material containing water.
Patent Documents 2 and 3 disclose that dispersibility in water is improved by using a polyisocyanate containing a sulfonic acid group. However, there is a problem that the synthetic product becomes cloudy due to poor compatibility between the sulfonic acid group and the polyisocyanate. If a highly organic sulfonic acid or its amine salt is used to improve this cloudiness, the appearance of the coating film becomes poor, and it is necessary to modify a large amount of the sulfonic acid or its amine salt, which leads to problems of insufficient water resistance and reduced hardness of the coating film.
Patent Documents 4 and 5 disclose that the hardness and solvent resistance of a coating film can be improved by using a modified polyisocyanate obtained by reaction with an aminosulfonic acid having a specific structure. On the other hand, there is a problem that the appearance of the coating film is deteriorated due to the relatively high hydrophobicity of the aminosulfonic acid having a specific structure. In addition, there is also a problem that the water resistance and stain resistance are poor, despite the relatively high hydrophobicity of the aminosulfonic acid.

The present invention has been made in consideration of the above circumstances, and provides a polyisocyanate composition that is highly transparent and has excellent appearance and water resistance when formed into a coating film. The present invention also provides a coating composition and a coating substrate that use the polyisocyanate composition.

That is, the present invention includes the following aspects.
(1) A polyisocyanate having in its molecule at least one hydrophilic anion group selected from the group consisting of a carboxylate anion group, a phosphate anion group, and a sulfonate anion group;
a cationic compound,
a molar ratio of the hydrophilic anion group to the cationic compound is 1.002 or more and 1.2 or less;
The cationic compound is a tertiary ammonium cation of an amine compound represented by the following general formula (1):
The polyisocyanate containing a hydrophilic anion group in the molecule is obtained by reacting an amine salt of a sulfonic acid having a hydroxyl group with a polyisocyanate, and
The polyisocyanate composition , wherein the amine salt of a sulfonic acid having a hydroxyl group is a salt of a sulfonic acid having a hydroxyl group and an amine compound represented by general formula (1).

(In general formula (1), R ¹¹ , R ¹² and R ¹³ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may contain an ether bond. At least one selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may contain a ring structure, and two or more selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may be bonded to each other to form a ring structure. The ring structure is an aromatic ring, a cycloalkyl group having 5 or 6 carbon atoms, a 5- or 6-membered ring in which R ¹¹ and R ¹² are bonded to each other, or a multi-membered multiple ring in which R ¹¹ , R ¹² and R ¹³ are bonded to each other.)

(2) The polyisocyanate composition according to (1), wherein a molar ratio of the hydrophilic anion group to the cationic compound is 1.01 or more and 1.1 or less.

(3) The polyisocyanate composition according to (1) or (2), wherein the hydrophilic anion group contains a sulfonate anion group.

(4) The amine compound represented by the general formula (1) is R ¹¹ , R ¹² , and R ¹³ (5) The polyisocyanate composition according to any one of (1) to (3), comprising an amine compound in which each of the above is a linear aliphatic hydrocarbon group.

(5) The polyisocyanate composition according to (1), wherein the sulfonic acid having a hydroxyl group is a compound represented by the following general formula (2):

(In the general formula (2), R ²¹ R is a hydrocarbon group having 1 to 10 carbon atoms which may contain at least one selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, a carbonyl group, and an imino group. ²¹ may include a ring structure. The ring structure is an aromatic ring, a 5- or 6-membered ring containing two nitrogen atoms, or a 5- or 6-membered ring containing a nitrogen atom and an oxygen atom.

(6) The polyisocyanate composition according to any one of (1) to (5), wherein the polyisocyanate has an isocyanurate group.

(7) The polyisocyanate composition according to any one of (1) to (6), wherein the polyisocyanate is at least one selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

(8) A coating composition comprising the polyisocyanate composition according to any one of (1) to (7).

(9) A coating substrate coated with the coating composition according to (8) .

The polyisocyanate composition of the above embodiment can provide a polyisocyanate composition that is highly transparent and has excellent appearance and water resistance when formed into a coating film. The coating composition of the above embodiment contains the polyisocyanate composition, and has excellent appearance and water resistance when formed into a coating film. The coating substrate of the above embodiment has a coating film formed by curing the coating composition, and the coating film has excellent appearance and water resistance.

The following describes in detail the form for carrying out the present invention (hereinafter, referred to as the "present embodiment"). Note that the present invention is not limited to the present embodiment. The present invention can be carried out with appropriate modifications within the scope of its gist.

<Polyisocyanate composition>
The polyisocyanate composition of the present embodiment contains a polyisocyanate containing, in the molecule, one or more hydrophilic anion groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, and a sulfonic acid group, and a cationic compound.

The molar ratio of the hydrophilic anionic group to the cationic compound (hydrophilic anionic group/cationic compound) is 1.002 or more and 1.20 or less.
The lower limit of the molar ratio is 1.002, preferably 1.005, and more preferably 1.01. On the other hand, the upper limit of the molar ratio is 1.20, preferably 1.18, more preferably 1.15, and even more preferably 1.10.
That is, the molar ratio of the hydrophilic anion group to the cationic compound (hydrophilic anion group/cationic compound) is from 1.002 to 1.20, preferably from 1.005 to 1.18, more preferably from 1.01 to 1.15, and even more preferably from 1.01 to 1.10.
When the molar ratio of the hydrophilic anion group/cationic compound is within the above range, the polyisocyanate composition becomes more transparent and tends to have better water resistance when formed into a coating film. The molar ratio of the hydrophilic anion group/cationic compound can be adjusted to be within the above range by changing the blending amount of the polyisocyanate containing a hydrophilic anion group in the molecule and the cationic compound. The molar ratio of the hydrophilic anion group/cationic compound can be calculated using the method described in the examples below.

In another embodiment, the polyisocyanate composition contains a polyisocyanate containing a sulfonate anion group in the molecule and a tertiary ammonium cation of an amine compound represented by the following general formula (1) (hereinafter, sometimes referred to as "amine compound (1)").

(In general formula (1), R ¹¹ , R ¹² and R ¹³ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may contain an ether bond. At least one selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may contain a ring structure, and two or more selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may be bonded to each other to form a ring structure. The ring structure is an aromatic ring, a cycloalkyl group having 5 or 6 carbon atoms, a 5- or 6-membered ring in which R ¹¹ and R ¹² are bonded to each other, or a multi-membered multiple ring in which R ¹¹ , R ¹² and R ¹³ are bonded to each other.)

The molar ratio of the sulfonate anion group to the tertiary ammonium cation (sulfonate anion group/tertiary ammonium cation) is from 1.01 to 1.2, preferably from 1.01 to 1.15, more preferably from 1.01 to 1.1, and even more preferably from 1.01 to 1.08.
When the molar ratio of sulfonate anion group/tertiary ammonium cation is within the above range, the polyisocyanate composition becomes more transparent and tends to have better water resistance when formed into a coating film. The molar ratio of sulfonate anion group/tertiary ammonium cation can be adjusted to be within the above range by changing the blending amount of polyisocyanate containing sulfonate anion group in the molecule and tertiary ammonium cation of amine compound (1). The molar ratio of sulfonate anion group/tertiary ammonium cation can be calculated using the method described in the examples below.

The polyisocyanate composition of the present embodiment has the above-mentioned structure, and thus a polyisocyanate composition having high transparency can be obtained, as shown in the examples described later. In addition, by using the polyisocyanate composition of the present embodiment, a coating film having excellent appearance and water resistance can be obtained.
The components of the polyisocyanate composition of the present embodiment will be described in detail.

<Isocyanate component>
The polyisocyanate composition of the present embodiment usually contains unreacted polyisocyanate, i.e., polyisocyanate not containing a hydrophilic anion group in the molecule, as an isocyanate component. Furthermore, various properties of the polyisocyanate composition of the present embodiment described below are properties in a state in which the composition contains a polyisocyanate containing a hydrophilic anion group in the molecule and an unreacted polyisocyanate (a polyisocyanate not containing a hydrophilic anion group in the molecule), unless otherwise specified.

In addition, in the polyisocyanate composition of this embodiment, the ratio of unreacted polyisocyanate to polyisocyanate containing hydrophilic anion groups in the molecule can be calculated, for example, from the ratio of isocyanate groups containing hydrophilic anion groups in the molecule to 100 moles of isocyanate groups in the raw material polyisocyanate.

[Polyisocyanate containing hydrophilic anionic groups in the molecule]
The polyisocyanate containing a hydrophilic anion group in the molecule, which is contained in the polyisocyanate composition of the present embodiment, is a reaction product obtained by reacting a compound having a hydrophilic anion group or a cationic salt thereof with a polyisocyanate, and is preferably a reaction product obtained by reacting a cationic salt of a compound having a hydrophilic anion group with a polyisocyanate.

Among them, the polyisocyanate containing a hydrophilic anion group in the molecule is preferably a polyisocyanate containing a sulfonate anion group in the molecule, more preferably a reaction product obtained by reacting a sulfonic acid having a hydroxyl group or its amine salt with a polyisocyanate, and even more preferably a reaction product obtained by reacting an amine salt of a sulfonic acid having a hydroxyl group with a polyisocyanate. In addition, the amine salt of a sulfonic acid having a hydroxyl group is preferably a salt of a sulfonic acid having a hydroxyl group and an amine compound (1) described later.

(Compound having a hydrophilic anion group)
Examples of the compound having a hydrophilic anion group include a compound containing a carboxylic acid group, a compound containing a phosphoric acid group, a compound containing a sulfonic acid group, etc. Among them, the compound having a hydrophilic anion group preferably includes a compound containing a sulfonic acid group.
The compound having a hydrophilic anion group preferably has one or more active hydrogen groups for reacting with the isocyanate group of the polyisocyanate per molecule of the compound having a hydrophilic anion group.Specific examples of the active hydrogen group include a hydroxyl group, a mercapto group, a carboxylic acid group, an amino group, and a thiol group.

The compound containing a carboxylic acid group is not particularly limited, but examples thereof include monohydroxycarboxylic acids such as 1-hydroxyacetic acid, 3-hydroxypropanoic acid, 12-hydroxy-9-octadecanoic acid, hydroxypivalic acid, and lactic acid; and carboxylic acids containing a hydroxyl group such as polyhydroxycarboxylic acids such as dimethylolacetic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dimethylolpropionic acid, and 4-(hydroxymethyl)cyclohexylcarboxylic acid. Among these, hydroxypivalic acid, dimethylolpropionic acid, and 4-(hydroxymethyl)cyclohexylcarboxylic acid are preferred.

Compounds containing a phosphate group are not particularly limited, but examples include acid phosphate esters, acid phosphites, acid hypophosphites, and specific polyether phosphonates (for example, those commercially available under the trade name RHODAFAC (registered trademark) (Solvay Nicca Co., Ltd.)). Among these, acid phosphate esters are preferred. Specific examples of acid phosphate esters include 2-hydroxyethyl phosphate.

From the viewpoint of water dispersibility, the polyisocyanate composition preferably has a phosphorus atom content of 0.03 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.1 mass% or more, relative to the total amount (100 mass%) of the polyisocyanate composition. When the phosphorus atom content is equal to or more than the above lower limit, the interfacial tension decreases, and the composition tends to exhibit better water dispersibility.
On the other hand, from the viewpoint of coating film properties, the polyisocyanate composition preferably has a phosphorus atom content of 6.0 mass% or less, more preferably 3.0 mass% or less, and even more preferably 1.0 mass% or less, relative to the total amount (100 mass%) of the polyisocyanate composition. When the phosphorus atom content is equal to or less than the above upper limit, the coating film properties tend to be better due to the increased amount of isocyanate groups used for crosslinking.
The method for controlling the phosphorus atom content within the above range includes, but is not limited to, a method of adjusting the compounding ratio of the compound containing a phosphoric acid group to the raw material polyisocyanate compound. The phosphorus atom content is measured by inductively coupled plasma atomic emission spectrometry (ICP-AES).

Compounds containing a sulfonic acid group are not particularly limited, but examples include sulfonic acids containing a hydroxyl group and sulfonic acids containing an amino group. Of these, sulfonic acids containing a hydroxyl group are preferred.

Examples of sulfonic acids containing an amino group include 2-aminoethanesulfonic acid, 2-methylaminoethanesulfonic acid, 2-(cyclohexylamino)-ethanesulfonic acid, 3-(cyclohexylamino)-propanesulfonic acid, 4-aminotoluene-2-sulfonic acid, 5-aminotoluene-2-sulfonic acid, 2-aminonaphthalene-4-sulfonic acid, 4-aminobenzenesulfonic acid, and 3-aminobenzenesulfonic acid.

Examples of sulfonic acids containing hydroxyl groups include compounds represented by the following general formula (2) and specific polyether sulfonates (e.g., those commercially available under the trade name Tegomer (registered trademark) (The Goldschmidt AG, Essen, Germany)), but the compounds represented by the following general formula (2) are preferred.

In the formula (2), ^R21 is a hydrocarbon group having 1 to 10 carbon atoms which may contain at least one selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, a carbonyl group, and an imino group. ^R21 may contain a ring structure. The ring structure is an aromatic ring, a 5- or 6-membered ring containing two nitrogen atoms, or a 5- or 6-membered ring containing a nitrogen atom and an oxygen atom.

In general formula (2), R ²¹ is a hydrocarbon group having 1 to 10 carbon atoms which may contain at least one selected from the group consisting of a hydroxyl group, an ester bond (-COO-), an ether bond (-O-), a carbonyl group (-C(=O)-), an imino group (-NR-), and a ring structure.

The hydrocarbon group having 1 to 10 carbon atoms may be a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a divalent aromatic hydrocarbon group having 6 to 10 carbon atoms. The divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms is preferably a chain alkylene group having 1 to 6 carbon atoms. When the chain alkylene group has 1 to 6 carbon atoms, the chain alkylene group may include a ring structure in part. The alkylene group having 1 to 6 carbon atoms may be linear or branched.

Among these, R ²¹ is preferably a chain-like alkylene group having 1 to 6 carbon atoms, a divalent aromatic hydrocarbon group (arylene group) having 6 to 10 carbon atoms, a divalent alkylene group containing an aromatic ring and having 1 to 10 carbon atoms, a divalent alkylene group containing a 5- or 6-membered ring containing two nitrogen atoms and having 1 to 6 carbon atoms, or a divalent alkylene group containing a 5- or 6-membered ring containing a nitrogen atom and an oxygen atom and having 1 to 6 carbon atoms.

Preferred examples of the sulfonic acid (2) include 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, 4-hydroxybutanesulfonic acid, 5-hydroxypentanesulfonic acid, 6-hydroxyhexanesulfonic acid, hydroxybenzenesulfonic acid, hydroxy(methyl)benzenesulfonic acid, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid, and 2-hydroxy-3-morpholinopropanesulfonic acid.
These compounds are merely a part of the preferred sulfonic acids (2), and the preferred sulfonic acids (3) are not limited to these.
These sulfonic acids (2) may be used alone or in combination of two or more.

Among them, the sulfonic acid having a hydroxyl group is preferably at least one selected from the group consisting of 2-hydroxyethanesulfonic acid, 3-hydroxypropanesulfonic acid, hydroxybenzenesulfonic acid, and hydroxy(methyl)benzenesulfonic acid.

In addition, when the polyisocyanate composition of this embodiment contains two or more types of amine salts of sulfonic acid, the sulfonic acids (2) may be the same or different.

In addition, it is preferable that the sulfonic acid used in the polyisocyanate containing a sulfonate anion group in the molecule forms a salt with the amine compound (1).

(Polyisocyanate)
The polyisocyanate used in the polyisocyanate containing a sulfonate anion group in the molecule is not particularly limited, and examples thereof include polyisocyanates derived from at least one diisocyanate selected from aliphatic diisocyanates, alicyclic diisocyanates, and aromatic diisocyanates. From the viewpoint of industrial availability, the polyisocyanate used in the polyisocyanate containing a sulfonate anion group in the molecule is preferably at least one selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates.

Aliphatic diisocyanates are not particularly limited, but examples include 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, ethyl (2,6-diisocyanato)hexanoate, 1,6-diisocyanatohexane (hereinafter sometimes referred to as "HDI"), 1,9-diisocyanatononane, 1,12-diisocyanatododecane, 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane, etc.

Alicyclic diisocyanates are not particularly limited, but examples include 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (hereinafter sometimes referred to as "hydrogenated XDI"), 1,3- or 1,4-diisocyanatocyclohexane, 3,5,5-trimethyl-1-isocyanato-3-(isocyanatomethyl)cyclohexane (hereinafter sometimes referred to as "IPDI"), 4-4'-diisocyanato-dicyclohexylmethane (hereinafter sometimes referred to as "hydrogenated MDI"), 2,5- or 2,6-diisocyanatomethylnorbornane, etc.

Aromatic diisocyanates include, but are not limited to, xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, etc.

Among them, the diisocyanates preferably used are HDI, IPDI, hydrogenated XDI, and hydrogenated MDI.

The polyisocyanate derived from the above diisocyanate is not particularly limited, but examples thereof include the polyisocyanates shown in (a) to (h) below.
(a) a polyisocyanate having a uretdione group obtained by cyclodimerization of two isocyanate groups;
(b) polyisocyanates having isocyanurate groups or iminooxadiazinedione groups obtained by cyclotrimerization of three isocyanate groups;
(c) polyisocyanates having biuret groups obtained by reacting three isocyanate groups with one water molecule;
(d) polyisocyanates having oxadiazinetrione groups obtained by reacting two isocyanate groups with one molecule of carbon dioxide;
(e) polyisocyanates having a plurality of urethane groups obtained by reacting one isocyanate group with one hydroxyl group;
(f) polyisocyanates having an allophanate group obtained by reacting two isocyanate groups with one hydroxyl group;
(g) polyisocyanates having an acylurea group obtained by reacting one isocyanate group with one carboxyl group;
(h) Polyisocyanates having a urea group obtained by reacting one isocyanate group with one primary or secondary amine.

Among these, the polyisocyanate used for the polyisocyanate containing a sulfonate anion group in the molecule is preferably (b) above, and more preferably a polyisocyanate having an isocyanurate group.

The polyisocyanate used in the polyisocyanate containing a sulfonate anion group in the molecule may also contain an aliphatic triisocyanate. Examples of the aliphatic triisocyanate include 1,3,6-triisocyanatohexane, 1,8-diisocyanato-4-isocyanatomethyloctane, and 2-isocyanatoethyl-2,6-diisocyanato-hexanoate.

These polyisocyanates may also be modified with a nonionic hydrophilic group such as an alkoxy polyalkylene glycol, or a vinyl polymer having a hydroxyl group and a nonionic hydrophilic group.

These polyisocyanates can be used alone or in combination of two or more.

- Method for Producing Polyisocyanate There is no particular limitation on the method for producing a polyisocyanate containing an isocyanurate group. For example, there may be mentioned a method in which a diisocyanate is subjected to an isocyanurate reaction using a catalyst or the like, the reaction is stopped when a predetermined conversion rate is reached, and the unreacted diisocyanate is removed.

The catalyst used in the above-mentioned isocyanurate reaction is not particularly limited, but is preferably one that exhibits basicity. Specific examples thereof include hydroxides and weak organic acid salts of tetraalkylammonium, hydroxides and weak organic acid salts of hydroxyalkylammonium, alkali metal salts of alkylcarboxylic acids, metal alcoholates, aminosilyl group-containing compounds, Mannich bases, combined use of tertiary amines with epoxy compounds, phosphorus-based compounds, and the like.
Examples of tetraalkylammonium include tetramethylammonium and tetraethylammonium.
Examples of the organic weak acid include acetic acid and capric acid.
Examples of hydroxyalkylammonium include trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, and triethylhydroxyethylammonium.
Examples of the alkyl carboxylic acid include acetic acid, caproic acid, octylic acid, and myristic acid.
Examples of the alkali metal salt include tin, zinc, and lead.
Examples of the metal alcoholate include sodium alcoholate and potassium alcoholate.
An example of the aminosilyl group-containing compound is hexamethyldisilazane.
An example of the phosphorus-based compound is tributylphosphine.

The amount of these catalysts used is preferably 10 ppm or more and 1.0% or less based on the total mass of the diisocyanate (and, if necessary, alcohol) that is the raw material. In order to terminate the isocyanurate reaction, the catalyst may be inactivated by adding an acidic substance that neutralizes the catalyst, by thermal decomposition, chemical decomposition, or the like. Examples of acidic substances that neutralize the catalyst include phosphoric acid and acidic phosphate esters.

The yield of polyisocyanate generally tends to be 10% by mass or more and 70% by mass or less. Polyisocyanate obtained with a higher yield tends to have a higher viscosity. The yield can be calculated from the ratio of the mass of the polyisocyanate obtained to the total mass of the raw material components.

The reaction temperature of the isocyanurate reaction is not particularly limited, but is preferably 50°C or higher and 200°C or lower, and more preferably 50°C or higher and 150°C or lower. When the reaction temperature is equal to or higher than the lower limit, the reaction tends to proceed more easily, and when the reaction temperature is equal to or lower than the upper limit, side reactions that cause coloring tend to be suppressed more effectively.

After the isocyanurate reaction is completed, it is preferable to remove the unreacted diisocyanate monomer by a thin film evaporator, extraction, or the like. Even if the polyisocyanate contains unreacted diisocyanate, the diisocyanate content is preferably 3.0% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.5% by mass or less, based on the total mass of the polyisocyanate. When the concentration of the residual unreacted diisocyanate monomer is within the above range, the curing property tends to be better.

(Method for producing polyisocyanate containing hydrophilic anion group in the molecule)
The polyisocyanate containing a hydrophilic anion group in the molecule can be obtained by reacting a compound having a hydrophilic anion group having an active hydrogen group or a cationic salt thereof with the above diisocyanate or the above polyisocyanate.

<Cationic Compound>
Examples of the cationic compound contained in the polyisocyanate composition of the present embodiment include inorganic bases and organic amine compounds.
The hydrophilic anionic group of the polyisocyanate containing the hydrophilic anionic group in the molecule is neutralized with a cationic compound.

Examples of inorganic bases include alkali metals such as lithium, sodium, potassium, rubidium, and cesium; alkaline earth metals such as magnesium, calcium, strontium, and barium; metals such as manganese, iron, cobalt, nickel, copper, zinc, silver, cadmium, lead, and aluminum; and ammonia.

An example of an organic amine compound is a tertiary ammonium cation of amine compound (1).

Among these, the cationic compound contained in the polyisocyanate composition of this embodiment preferably contains a tertiary ammonium cation of amine compound (1). The polyisocyanate composition of this embodiment may contain one type of amine compound (1) alone or two or more types in combination.

(In general formula (1), R ¹¹ , R ¹² and R ¹³ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may contain an ether bond. At least one selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may contain a ring structure, and two or more selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may be bonded to each other to form a ring structure. The ring structure is an aromatic ring, a cycloalkyl group having 5 or 6 carbon atoms, a 5- or 6-membered ring in which R ¹¹ and R ¹² are bonded to each other, or a multi-membered multiple ring in which R ¹¹ , R ¹² and R ¹³ are bonded to each other.)

In the polyisocyanate composition of this embodiment, it is preferable that the amine compound (1) forms a salt with the sulfonic acid.

[Amine compound (1)]
(R ¹¹ , R ¹² and R ¹³ )
In the general formula (1), R ¹¹ , R ¹² and R ¹³ are each independently a hydrocarbon group having from 1 to 10 carbon atoms which may contain an ether bond. R ¹¹ , R ¹² and R ¹³ may be the same or different.

The hydrocarbon group having 1 to 10 carbon atoms may be a monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, or may be a monovalent aromatic hydrocarbon group having 6 carbon atoms. The monovalent aliphatic hydrocarbon group having 1 to 10 carbon atoms is preferably a chain aliphatic hydrocarbon group (chain alkyl group) having 1 to 10 carbon atoms, or a cyclic aliphatic hydrocarbon group (cyclic alkyl group) having 3 to 10 carbon atoms. The chain aliphatic hydrocarbon group (chain alkyl group) having 1 to 10 carbon atoms may be linear or branched, but is preferably a linear aliphatic hydrocarbon group (straight-chain alkyl group) because it has high transparency and excellent appearance when made into a coating film. That is, in the general formula (1), it is preferable that R ¹¹ , R ¹² and R ¹³ are all linear aliphatic hydrocarbon groups (straight-chain alkyl groups).

Preferred examples of the amine compound (1) include trimethylamine, N,N-dimethylethylamine, N,N-dimethylethylamine, N,N-dimethylpropylamine, N-dimethylpentylamine, N,N-dimethylhexylamine, N,N-diethylmethylamine, N,N-methylethylbutylamine, triethylamine, N,N-dimethyloctylamine, N,N-dimethylisopropylamine, N,N-dimethylbutylamine, N,N-dimethylisobutylamine, N,N-dimethyloctylamine, N,N-dimethyl-2-ethylhexylamine, N,N-dimethyllaurylamine, N,N-diethylmethylamine, N,N-diethylbutylamine, N,N-diethylisopropylamine, N , N-diethylisobutylamine, N,N-dimethylheptylamine, N,N-dimethylnonylamine, N,N-dimethyldecylamine, N,N-diethylhexylamine, N,N-diethyloctylamine, N,N-diethyl-2-ethylhexylamine, N,N-diethylpentylamine, N,N-diethylheptylamine, N,N-diethylnonylamine, N,N-diethyldecylamine, N,N-diisopropylmethylamine, N,N-diisopropylethylamine, N,N-diisopropylbutylamine, N,N-diisopropyl-2-ethylhexylamine, N-methyl-dioctylamine, N,N-dimethylallylamine, N-methyldiallylamine, tripropylamine, tripropyla amine, tributylamine, N,N-diethylpropylamine, N,N-dibutylpropylamine, N,N-dipropyloctylamine, N,N-dimethylbenzylamine, N,N-dibutylmethylamine, N,N-dibutylethylamine, N,N-dibutylpentylamine, N,N-dibutylhexylamine, N,N-dibutylheptylamine, N,N-dibutyloctylamine, N,N-dibutyl-2-ethylhexylamine, N,N-dibutylnonylamine, N,N-dibutyldecylamine, triamylamine, trihexylamine, N,N-diethylbenzylamine, N,N-dibenzylmethylamine, tribenzylamine, N,N-dimethyl-4-methylbenzylamine, N,N-dimethylcyclohex ...diethylbenzylamine, N,N-dibenzylmethylamine, tribenzylamine, N,N-dimethyl-4-methylbenzylamine, N,N-dimethylcyclohexylamine, N,N-dimethylcyclohexylamine, N,N-dimethylcyclohexylamine, N,N-dimethylcyclohexylamine, N,N-dimethylcyclohexylamine Examples of the amine compounds include xylamine, N,N-diethylcyclohexylamine, N,N-dicyclohexylmethylamine, N,N-dicyclohexylethylamine, tricyclohexylamine, N-methylpyrrolidine, N-ethylpyrrolidine, N-propylpyrrolidine, N-butylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, N-propylpiperidine, N-butylpiperidine, N-methylmorpholine, N-ethylmorpholine, N-propylmorpholine, N-butylmorpholine, N-sec-butylmorpholine, N-tert-butylmorpholine, N-isobutylmorpholine, quinuclidine, N,N-dimethylphenylamine, N,N-diethylphenylamine, and N,N-diphenylmethylamine. These compounds are merely a part of the preferred amine compounds (1), and the preferred amine compounds (1) are not limited to these. Furthermore, these amine compounds (1) may be used alone or in combination of two or more.

Among them, trimethylamine, N,N-dimethylethylamine, N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-dimethyl-2-ethylhexylamine, N,N-diethylmethylamine, N,N-diisopropylethylamine, N,N-diisopropyl-2-ethylhexylamine, N,N-dimethylallylamine, tripropylamine, tributylamine, N,N-diethylpropylamine, N,N-dibutylpropylamine, N,N-dipropyloctylamine, N,N-dibutylpentylamine, N,N-dibutylhexylamine, Amine, N,N-dibutylheptylamine, N,N-dibutyloctylamine, triamylamine, trihexylamine, N,N-dimethylcyclohexylamine, N,N-dicyclohexylmethylamine, N,N-dibutylpentylamine, N,N-dibutylhexylamine, N,N-dibutylheptylamine, N,N-dibutyloctylamine, triamylamine, trihexylamine, N-methylpyrrolidine, N-methylpiperidine, N-ethylpiperidine, N-methylmorpholine, N-ethylmorpholine, or N-isobutylmorpholine is preferred.

Furthermore, since R ¹¹ , R ¹² and R ¹³ are all linear aliphatic hydrocarbon groups (linear alkyl groups), trimethylamine, N,N-dimethylethylamine, N,N-dimethylpropylamine, N,N-dimethylbutylamine, N,N-diethylmethylamine, N-dimethylpentylamine, N,N-dimethylhexylamine, N,N-diethylmethylamine, N,N-methylethylbutylamine, triethylamine, N,N-dimethyloctylamine, tripropylamine, tributylamine, N,N-dipropyloctylamine, N,N-dibutylpentylamine, N,N-dibutylhexylamine, N,N-dibutylheptylamine, N,N-dibutyloctylamine, triamylamine or trihexylamine is particularly preferred.

[Other amine compounds]
The polyisocyanate composition of the present embodiment may contain, in addition to the tertiary ammonium cation of the amine compound (1), a tertiary ammonium cation of another amine compound.
The other amine compound is not particularly limited as long as it is other than the above amine compound (1). Specific examples of the other amine compound include N,N-dimethylundecylamine, N,N-dimethyldodecylamine, N,N-dimethyltridecylamine, N,N-dimethylstearylamine, N,N-diethyllaurylamine, N,N-diethylundecylamine, N,N-diethyldodecylamine, N,N-diethyltridecylamine, N,N-diethylstearylamine, N,N-dibutylundecylamine, N,N-dibutyldodecylamine, N,N-dibutyltridecylamine, and N,N-dibutylstearylamine. These other amine compounds may be used alone or in combination of two or more.

<Method of producing a cationic salt of a compound having a hydrophilic anion group>
When the compound having the hydrophilic anionic group forms a salt with the cationic compound, i.e., when it is a cationic salt of the compound having a hydrophilic anionic group, it can be obtained, for example, by mixing the compound having the hydrophilic anionic group with the cationic compound and carrying out a neutralization reaction.

The neutralization reaction may be carried out before reacting with the polyisocyanate. Alternatively, it may be carried out simultaneously with the reaction with the polyisocyanate. Alternatively, it may be carried out by adding an amine compound after reacting the polyisocyanate with a sulfonic acid having a hydroxyl group.

The neutralization reaction is preferably carried out before the reaction with the polyisocyanate.
In the neutralization reaction, the ratio at which the compound having a hydrophilic anionic group and the cationic compound are mixed is, in terms of the molar ratio of the compound having a hydrophilic anionic group/cationic compound, from 1.002 to 1.20, preferably from 1.005 to 1.18, more preferably from 1.01 to 1.15, and even more preferably from 1.01 to 1.10.

If the neutralization reaction is carried out in advance, the temperature and time can be appropriately determined depending on the progress of the reaction, but the temperature is usually preferably from about 0°C to about 100°C, and the mixing time is preferably from about 10 minutes to about 24 hours.

The solvent used in preparing the cationic salt of the compound having the hydrophilic anion group is preferably water or a hydrophilic solvent.The hydrophilic solvent is not particularly limited, but may be, for example, alcohols, ether alcohols, ketones, amide solvents, etc.These solvents may be used alone or in combination.
Examples of the alcohols include methanol, ethanol, propanol, butanol, and isopropanol.
Examples of the ether alcohols include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and dipropylene glycol monomethyl ether.
Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone.
Examples of the amide solvent include N,N-dimethylformamide and N,N-dimethylacetamide.

After the neutralization reaction, it is preferable to remove the water or hydrophilic solvent.

<Characteristics of Polyisocyanate Composition>
From the viewpoints of emulsifiability and coating film properties, the polyisocyanate composition of the present embodiment has, relative to 100 molar amounts of isocyanate groups in the raw material polyisocyanate, preferably 0.25 to 50 molar amounts of isocyanate groups modified with a compound having a hydrophilic anion group, more preferably 0.5 to 20 molar amounts of isocyanate groups modified, and even more preferably 1 to 10 molar amounts of isocyanate groups modified.

The isocyanate group content of the polyisocyanate composition of this embodiment is preferably 10% by mass or more and 25% by mass or less, and more preferably 15% by mass or more and 24% by mass or less, from the viewpoint of the solvent resistance of the coating film, when the non-volatile content is taken as 100% by mass. The method of controlling the isocyanate group content within the above range is not particularly limited, but an example of the method is to adjust the compounding ratio of the compound having a hydrophilic anion group and the polyisocyanate.

Moreover, from the viewpoint of the solvent resistance of the coating film, the number average molecular weight of the polyisocyanate used in the polyisocyanate composition of the present embodiment (including the polyisocyanate containing a hydrophilic anion group in the molecule and the unreacted polyisocyanate) is preferably from 450 to 2,000, more preferably from 500 to 1800, and even more preferably from 550 to 1550. The method for controlling the number average molecular weight within the above range is not particularly limited, but examples thereof include a method of adjusting the compounding ratio of a compound having a hydrophilic anion group, a cationic compound, and a polyisocyanate.
The number average molecular weight can be measured, for example, by using gel permeation chromatography (GPC).

The average number of functional groups of the polyisocyanate (including polyisocyanate containing hydrophilic anion groups in the molecule and unreacted polyisocyanate) used in the polyisocyanate composition of this embodiment is preferably 1.8 to 6.2, more preferably 2.0 to 5.6, and even more preferably 2.5 to 4.6, from the viewpoint of the solvent resistance of the coating film and the isocyanate group retention rate. The method of controlling the average number of functional groups within the above range is not particularly limited, but examples thereof include a method of adjusting the compounding ratio of a compound having a hydrophilic anion group, a cationic compound, and a polyisocyanate.

In this embodiment, the isocyanate group content, non-volatile content, and average number of functional groups can be measured by the method described in the Examples below.

<Other ingredients>
The polyisocyanate composition of the present embodiment is a composition containing the polyisocyanate containing the above-mentioned hydrophilic anion group in the molecule, the unreacted polyisocyanate, and a cationic compound. The polyisocyanate composition of the present embodiment may contain other components in addition to the above-mentioned polyisocyanate containing the above-mentioned hydrophilic anion group in the molecule, the unreacted polyisocyanate, and the cationic compound. The other components are not particularly limited, but may include, for example, a solvent, an antioxidant, a light stabilizer, a polymerization inhibitor, a surfactant, etc.

The solvent used in the polyisocyanate composition of this embodiment may be a hydrophilic solvent or a hydrophobic solvent. These solvents may be used alone or in combination.

The hydrophobic solvent is not particularly limited, but examples thereof include mineral spirits, solvent naphtha, LAWS (Low Aromatic White Spirit), HAWS (High Aromatic White Spirit), toluene, xylene, cyclohexane, esters, ketones, and amides.
Examples of esters include ethyl acetate and butyl acetate.
Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.
Examples of the amides include N,N-dimethylformamide and N,N-dimethylacetamide.

The hydrophilic solvent is not particularly limited, but examples thereof include alcohols, ethers, and esters of ether alcohols.
Examples of the alcohols include methanol, ethanol, propanol, isopropanol, and 2-ethylhexanol.
Examples of the ethers include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, and dipropylene glycol dimethyl ether.
Examples of esters of ether alcohols include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and dipropylene glycol monomethyl ether acetate.

In the polyisocyanate composition of this embodiment, the content of the solvent is preferably 0% by mass or more and 90% by mass or less, more preferably 0% by mass or more and 50% by mass or less, and even more preferably 0% by mass or more and 30% by mass or less, based on the total mass of the polyisocyanate composition of this embodiment.

Examples of the antioxidant and light stabilizer include the following (a) to (e). These may be contained alone or in combination of two or more.
(a) aliphatic, aromatic or alkyl-substituted aromatic esters of phosphoric acid or phosphorous acid, and hypophosphorous acid derivatives;
(b) Phosphorus compounds such as phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonic acid, polyphosphonates, dialkyl pentaerythritol diphosphites, and dialkyl bisphenol A diphosphites;
(c) phenol derivatives (particularly, hindered phenol compounds);
(d) Sulfur-containing compounds, such as thioether compounds, dithioacid salt compounds, mercaptobenzimidazole compounds, thiocarbanilide compounds, and thiodipropionate compounds;
(e) Tin compounds such as tin maleate and dibutyltin monoxide

Examples of polymerization inhibitors include hydroquinones, phenols, cresols, catechols, and benzoquinones. Specific examples of polymerization inhibitors include benzoquinone, p-benzoquinone, p-toluquinone, p-xyloquinone, naphthoquinone, 2,6-dichloroquinone, hydroquinone, trimethylhydroquinone, catechol, p-t-butylcatechol, 2,5-di-t-butylhydroquinone, monomethylhydroquinone, p-methoxyphenol, 2,6-di-t-butyl-p-cresol, and hydroquinone monomethyl ether. These may be contained alone or in combination of two or more.

Examples of surfactants include known anionic surfactants, cationic surfactants, amphoteric surfactants, etc.

In the polyisocyanate composition of this embodiment, the total content of the antioxidant, light stabilizer, polymerization inhibitor, and surfactant is preferably 0% by mass or more and 10% by mass or less, more preferably 0% by mass or more and 5% by mass or less, and even more preferably 0% by mass or more and 2% by mass or less, based on the total mass of the polyisocyanate composition of this embodiment.

<Method for producing polyisocyanate composition>
The method for producing the polyisocyanate composition of the present embodiment preferably includes, for example, a step of mixing and reacting (A) a cationic salt of a compound having a hydrophilic anion group with a polyisocyanate.

Alternatively, the method for producing the polyisocyanate composition of this embodiment preferably includes, for example, a step of mixing and reacting (B) a compound having a hydrophilic anion group, a polyisocyanate, and the cationic compound.

In step (A), it is preferable that the cationic salt of the compound having a hydrophilic anionic group is prepared in advance and then added to the polyisocyanate. In step (A), when the cationic salt of the compound having a hydrophilic anionic group is prepared according to the above-mentioned "Method for producing a cationic salt of a compound having a hydrophilic anionic group", the molar ratio of the hydrophilic anionic group/cationic compound can be adjusted to 1.002 or more and 1.2 or less by changing the compounding ratio of the compound having a hydrophilic anionic group and the cationic compound.

In step (B), the compound having a hydrophilic anion group and the cationic compound may be added to the polyisocyanate simultaneously or in order. In step (B), the molar ratio of hydrophilic anion group/cationic compound can be adjusted to 1.002 or more and 1.2 or less by changing the compounding ratio of the compound having a hydrophilic anion group and the cationic compound.

Among these, step (A) is preferred, and it is more preferred that the cationic salt of the compound having a hydrophilic anion group is prepared in advance and then added to the polyisocyanate.

In the reaction process, the mixing ratio of the compound having a hydrophilic anion group having a hydroxyl group or its cationic salt to the polyisocyanate is, from the viewpoint of emulsifiability and coating film properties, preferably in the range of 2 to 400 in terms of the molar ratio of isocyanate groups to hydroxyl groups, more preferably in the range of 5 to 200, and even more preferably in the range of 10 to 100.

In this reaction process, the reaction temperature and reaction time are appropriately determined depending on the progress of the reaction, but the reaction temperature is preferably 0°C or higher and 150°C or lower, and the reaction time is preferably 30 minutes or higher and 48 hours or lower.

In addition, in the reaction step, a known ordinary catalyst may be used in some cases. The catalyst is not particularly limited, but examples thereof include the following (a) to (f). These may be used alone or in combination.
(a) Organotin compounds such as tin octanoate, tin 2-ethyl-1-hexanoate, tin ethylcaproate, tin laurate, tin palmitate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin dimaleate, dibutyltin dilaurate, dioctyltin diacetate, and dioctyltin dilaurate;
(b) organic zinc compounds such as zinc chloride, zinc octanoate, zinc 2-ethyl-1-hexanoate, zinc 2-ethylcaproate, zinc stearate, zinc naphthenate, and zinc acetylacetonate;
(c) an organotitanium compound;
(d) an organic zirconium compound;
(e) tertiary amines such as triethylamine, tributylamine, N,N-diisopropylethylamine, and N,N-dimethylethanolamine;
(f) Diamines such as triethylenediamine, tetramethylethylenediamine, and 1,4-diazabicyclo[2.2.2]octane.

In the method for producing the polyisocyanate composition of this embodiment, a solvent may or may not be used. The solvent used in the method for producing the polyisocyanate composition of this embodiment may be a hydrophilic solvent or a hydrophobic solvent. Examples of hydrophilic and hydrophobic solvents include those exemplified above in the other components.

In addition, in the method for producing the polyisocyanate composition of this embodiment, in addition to the compound having a hydrophilic anion group, the polyisocyanate, and the cationic compound, at least one selected from the group consisting of an antioxidant, a light stabilizer, a polymerization inhibitor, and a surfactant may be added. Examples of the antioxidant, the light stabilizer, the polymerization inhibitor, and the surfactant include the same ones as those exemplified in the other components described above.

<Coating composition>
The coating composition of the present embodiment includes the polyisocyanate composition described above.
The coating composition of the present embodiment can be used as an organic solvent-based coating composition, but is preferably used as an aqueous coating composition in which resins, which are coating film-forming components, are dissolved or dispersed in a medium mainly composed of water. In particular, the coating composition can be used for architectural paints, automotive paints, automotive repair paints, plastic paints, pressure sensitive adhesives, building materials, household water-based paints, other coating agents, sealants, inks, casting materials, elastomers, foams, plastic raw materials, and fiber treatment agents.

<Resins>
The resin used as the base agent is not particularly limited, but examples thereof include acrylic resins, polyester resins, polyether resins, epoxy resins, fluororesins, polyurethane resins, polyvinylidene chloride copolymers, polyvinyl chloride copolymers, vinyl acetate copolymers, acrylonitrile butadiene copolymers, polybutadiene copolymers, and styrene butadiene copolymers.
Among these, the resins are preferably acrylic resins or polyester resins.

(Acrylic resins)
The acrylic resins are not particularly limited, but examples thereof include acrylic resins obtained by polymerizing a single polymerizable monomer or a mixture of polymerizable monomers selected from the following (a) to (e), etc. These acrylic resins may be used alone or in combination.
(a) (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate;
(b) (meth)acrylic acid esters having active hydrogen, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate;
(c) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid;
(d) Unsaturated amides such as acrylamide, N-methylol acrylamide, and diacetone acrylamide;
(e) Other polymerizable monomers such as glycidyl methacrylate, styrene, vinyl toluene, vinyl acetate, acrylonitrile, dibutyl fumarate, p-styrenesulfonic acid, and allylsulfosuccinic acid.

The most common polymerization method is emulsion polymerization, but it can also be produced by suspension polymerization, dispersion polymerization, or solution polymerization. With emulsion polymerization, it is also possible to polymerize in stages.

(Polyester resins)
The polyester resins are not particularly limited, but examples thereof include polyester resins obtained by a condensation reaction between a single or a mixture of carboxylic acids and a single or a mixture of polyhydric alcohols.
Examples of the carboxylic acid include succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, and pyromellitic acid.
Examples of the polyhydric alcohol include diols, triols, and tetraols.
Examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 2-methyl-2,3-butanediol, 1,6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, 2-ethyl-hexanediol, 1,2-octanediol, 1,2-decanediol, 2,2,4-trimethylpentanediol, 2-butyl-2-ethyl-1,3-propanediol, and 2,2-diethyl-1,3-propanediol.
Examples of triols include glycerin and trimethylolpropane.
Examples of tetraols include diglycerin, dimethylolpropane, and pentaerythritol.

Alternatively, for example, polycaprolactones obtained by ring-opening polymerization of ε-caprolactone with the hydroxyl groups of low molecular weight polyols can also be used as polyester resins.

(Polyether resins)
Examples of the polyether resins include the following (a) to (d).
(a) polyether polyols obtained by adding an alkylene oxide or a mixture of alkylene oxides to a polyhydric hydroxy compound or a mixture of polyhydric hydroxy compounds in the presence of a strong basic catalyst;
(b) polyether polyols obtained by reacting a polyamine compound with an alkylene oxide;
(c) polyether polyols obtained by ring-opening polymerization of cyclic ethers;
(d) Polymer polyols obtained by polymerizing acrylamide or the like using the polyether polyols obtained by (a) to (c) as a medium.

Examples of the polyvalent hydroxy compound in (a) include the following compounds (i) to (vi).
(i) diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol, etc.;
(ii) Sugar alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol, and rhamnitol;
(iii) Monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, and ribosaccharides;
(iv) Disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and melibiose;
(v) Trisaccharides such as raffinose, gentianose, and melezitose;
(vi) Tetrasaccharides such as stachyose

Examples of the strong basic catalyst in (a) include hydroxides, alcoholates, and alkylamines of alkali metals. Examples of alkali metals include lithium, sodium, and potassium.

Examples of the alkylene oxide in (a) include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide.

Examples of the polyamine compound in (b) include ethylenediamines.

Examples of the cyclic ethers in (c) include tetrahydrofuran, etc.

In addition, in the coating composition of this embodiment, these resins can be used in combination with resins such as melamine-based hardeners, urethane dispersions, and urethane acrylic emulsions, if necessary.

It is also preferable that these resins are emulsified, dispersed or dissolved in water, and for this purpose, the carboxyl groups, sulfone groups, etc. contained in the resins can be neutralized.
The neutralizing agent for neutralizing the carboxyl group, sulfone group, etc. is not particularly limited, but examples thereof include ammonia, water-soluble amino compounds, etc.
Examples of the water-soluble amino compound include monoethanolamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, triethanolamine, butylamine, dibutylamine, 2-ethylhexylamine, ethylenediamine, propylenediamine, methylethanolamine, dimethylethanolamine, diethylethanolamine, morpholine, etc. These may be used alone or in combination of two or more.
Among these, the neutralizing agent is preferably a tertiary amine, and more preferably triethylamine or dimethylethanolamine.

<Other ingredients>
The coating composition of the present embodiment may further contain additives that are generally added to paints, in addition to the above-mentioned polyisocyanate composition and resins.The additives include, for example, inorganic pigments, organic pigments, extender pigments, silane coupling agents, titanium coupling agents, organic phosphates, organic phosphites, thickeners, leveling agents, thixotropic agents, defoamers, freeze stabilizers, matting agents, crosslinking reaction catalysts (catalysts for promoting curing), antiskinning agents, dispersants, wetting agents, fillers, plasticizers, lubricants, reducing agents, preservatives, antifungal agents, deodorants, anti-yellowing agents, ultraviolet absorbers, antistatic agents or charge regulators, antisettling agents, etc.These additives may be contained alone or in combination of two or more.

Examples of the crosslinking reaction catalyst (catalyst for promoting curing) include, but are not limited to, the following (a) or (b).
(a) Metal salts such as dibutyltin dilaurate, tin 2-ethylhexanoate, zinc 2-ethylhexanoate, and cobalt salts;
(b) Tertiary amines such as triethylamine, pyridine, methylpyridine, benzyldimethylamine, N,N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N,N'-endoethylenepiperazine, and N,N'-dimethylpiperazine.

The coating composition of this embodiment may further contain a surfactant in addition to the polyisocyanate composition and resins described above in order to improve dispersibility in paint.

The coating composition of this embodiment may further contain an antioxidant, a light stabilizer, and a polymerization inhibitor in addition to the polyisocyanate composition and resins described above in order to improve the storage stability of the coating.

<Coating substrate>
The coated substrate of the present embodiment is a substrate coated with the above-mentioned coating composition. The coated substrate of the present embodiment preferably has a coating layer containing the above-mentioned coating composition.

The coating substrate of this embodiment may comprise a desired substrate and, optionally, a conventional primer prior to coating.
Examples of the substrate include metal, wood, glass, stone, ceramic materials, concrete, rigid and flexible plastics, textiles, leather products, paper, and the like.

The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention.
In the examples and comparative examples, the physical properties and evaluations of the polyisocyanate compositions were measured as follows. Unless otherwise specified, "parts" and "%" mean "parts by mass" and "% by mass".
In the following, Examples 1 to 4, 18, and 19 are considered as reference examples.

<Measurement method>
[Physical Properties 1]
(viscosity)
The viscosity was measured at 25° C. using an E-type viscometer (manufactured by Tokimec Co., Ltd.) using a standard rotor (1°34′×R24). The rotation speeds were as follows:

(Rotation speed)
100 rpm (when viscosity is less than 128 mPa.s)
50 rpm (for viscosity between 128 mPa·s and 256 mPa·s)
20 rpm (for viscosity between 256 mPa·s and 640 mPa·s)
10 rpm (for viscosity between 640 mPa·s and 1280 mPa·s)
5 rpm (for viscosity between 1280 mPa·s and 2560 mPa·s)
2.5 rpm (2560 mPa.s or more and less than 5120 mPa.s)

[Physical Properties 2]
(Isocyanate Group Content)
The polyisocyanate compositions obtained in the Examples and Comparative Examples were used as samples to measure the isocyanate group content according to the method described in JIS K7301-1995 (Test method for tolylene diisocyanate-type prepolymers for thermosetting urethane elastomers). A more specific method for measuring the isocyanate group content is described below.

(1) 1 g (Wg) of a sample was placed in a 200 mL Erlenmeyer flask, and 20 mL of toluene was added to the flask to dissolve the sample.
(2) Then, 20 mL of a 2.0 N di-n-butylamine/toluene solution was added to the flask and allowed to stand for 15 minutes.
(3) 70 mL of 2-propanol was added to the flask and dissolved to obtain a solution.
(4) The solution obtained in (3) above was titrated with 1 mol/L hydrochloric acid to determine the sample titer (V1 mL).
(5) Even when no sample was added, the measurement was carried out in the same manner as in (1) to (3) above, and the blank titer (V0 mL) was calculated.
From the sample titration amount and blank titration amount obtained above, the isocyanate group content was calculated using the following formula.

Isocyanate group content (mass%) = (V0-V1) x 42/[W(1g) x 1000] x 100

[Physical Properties 3]
(Non-volatile content)
When the polyisocyanate compositions obtained in the Examples and Comparative Examples were used as samples and diluted with a solvent, the non-volatile content was calculated using the method shown below. First, the mass of an aluminum cup was precisely weighed (W0 g), and about 1 g of a sample was placed in the cup, and the mass of the cup before drying by heating (W1 g) was precisely weighed. Next, the cup containing the sample was heated in a dryer at 105° C. for 3 hours. Next, the cup after heating was cooled to room temperature, and the mass of the cup was precisely weighed again (W2 g). Next, the mass % of the dry residue in the sample was taken as the non-volatile content, and the non-volatile content was calculated using the formula shown below. In addition, when there was no dilution with a solvent, the non-volatile content was treated as being substantially 100%.

Non-volatile content (mass%) = (W2-W0)/(W1-W0) x 100

[Physical Properties 4]
(Number average molecular weight (Mn))
The number average molecular weight of the polyisocyanate composition was obtained by measuring the number average molecular weight against polystyrene standards by GPC measurement under the measurement conditions shown below.

(Measurement condition)
Apparatus: Tosoh Corporation HLC-8120GPC (product name)
Column: Tosoh Corporation TSKgel Super H1000 (product name) x 1 TSKgel Super H2000 (product name) x 1 TSKgel Super H3000 (product name) x 1 Carrier: Tetrahydrofuran Detection method: Differential refractometer

[Physical Properties 5]
(Average number of functional groups)
The average functionality is the number of isocyanate functional groups statistically possessed by one molecule of polyisocyanate, and was calculated using the following formula from the number average molecular weight (Mn) of the polyisocyanate obtained in "Physical Properties 4" and the isocyanate group content (NCO%) obtained in "Physical Properties 2".

Average number of functional groups = Mn x NCO%/420)

[Physical Properties 6]
(Molar ratio of hydrophilic anion group to cationic compound)
Based on the results of LC-MS and UV-MS measurements using a WATERS "UPLC," the molar ratio of hydrophilic anion group/cationic compound was calculated from each peak area.

<Evaluation method>
[Evaluation 1]
(Transparency of Polyisocyanate Composition)
The polyisocyanate compositions obtained in the Examples and Comparative Examples were visually inspected for the presence or absence of foreign matter or turbidity, and were evaluated according to the following evaluation criteria.

(Evaluation criteria)
◎: Transparent homogeneous liquid, transparent homogeneous liquid even after dilution with solvent ○: Transparent homogeneous liquid, slightly turbid after dilution with solvent △: Slightly turbid, turbid after dilution with solvent ×: Foreign matter or turbidity present

[Evaluation 2]
(Appearance of the coating)
Each coating composition obtained by the above method was used to coat a coating film having a thickness of 40 μm on a glass plate. The coating film was then dried under an atmosphere of 23° C. and 50% humidity, and the next day, the gloss value of the coating film obtained was measured using a gloss meter (a digital variable angle gloss meter UDV-6P (product name) manufactured by Suga Test Instruments Co., Ltd.) under the conditions of JIS Z8741 as a 60 degree gloss value. The appearance was evaluated according to the following evaluation criteria.

(Evaluation criteria)
○: 85% or more △: Less than 85% 65% or more ×: Less than 65%

[Evaluation 3]
(Water resistance of coating film)
Each coating composition obtained by the above method was applied to a glass plate with an applicator to a thickness of 40μ. Then, the coating was dried for 7 days under an atmosphere of 23°C and 50% humidity to obtain a coating film. Next, a silicon O-ring with a diameter of 20 mm was placed on the obtained coating film, and 0.5 g of water was poured into it. Then, the coating film was left at 23°C for 24 hours, and the state of the coating film after removing the water remaining on the surface was observed. The water resistance of the coating film was evaluated according to the following evaluation criteria. However, the coating film with the appearance of x in the above "Evaluation 2" was not measurable (x) because it was impossible to evaluate visually. Regarding the evaluation criteria, "blister" means a water bubble or swelling that occurs on the surface of the coating film.

(Evaluation criteria)
○: No change △: Whitening, no blistering ×: Blistering, whitening, or coating film dissolution

<Synthesis of sulfonic acid amine salt (neutralized salt)>
[Synthesis Example 1]
(Synthesis of neutralized salt S-1)
10 parts by mass of 1-propanol was added to 20 parts by mass of a 70% by mass aqueous solution of 2-hydroxyethanesulfonic acid (hereinafter sometimes abbreviated as "HES") and stirred to obtain a solution. Furthermore, sodium was weighed out so that the molar equivalent ratio of 2-hydroxyethanesulfonic acid to sodium was 1.05, and a liquid obtained by diluting with the same part by mass of 1-propanol was added dropwise to the above solution under stirring. Stirring was stopped one hour after the start of the dropwise addition, and the mixture was dehydrated and desolvated using an evaporator to obtain neutralized salt S-1 (2-hydroxyethanesulfonic acid/sodium salt).

[Synthesis Example 2]
(Synthesis of Neutralized Salt S-2)
A solution was obtained by adding 10 parts by mass of 1-propanol to 20 parts by mass of an 80% by mass aqueous solution of 3-hydroxypropanesulfonic acid (hereinafter sometimes abbreviated as "HPS") and stirring. Furthermore, tripropylamine (hereinafter sometimes abbreviated as "TnPA") was weighed out so that the molar equivalent ratio of HPS to tripropylamine was 1.005, and a liquid obtained by diluting with the same part by mass of 1-propanol was added dropwise to the solution under stirring. One hour after the start of the dropwise addition, stirring was stopped, and the mixture was dehydrated and desolvated with an evaporator to obtain neutralized salt S-2 (3-hydroxypropanesulfonic acid tripropylamine salt).

[Synthesis Example 3]
(Synthesis of Neutralized Salt S-3)
A neutralized salt S-3 (3-hydroxypropanesulfonic acid tripropylamine salt) was obtained in the same manner as in Synthesis Example 2, except that TnPA was weighed out so that the molar equivalent ratio of HPS to TnPA was 1.01.

[Synthesis Example 4]
(Synthesis of Neutralized Salt S-4)
A neutralized salt S-4 (3-hydroxypropanesulfonic acid tripropylamine salt) was obtained in the same manner as in Synthesis Example 2, except that TnPA was weighed out so that the molar equivalent ratio of HPS to TnPA was 1.03.

[Synthesis Example 5]
(Synthesis of Neutralized Salt S-5)
A neutralized salt S-5 (3-hydroxypropanesulfonic acid tripropylamine salt) was obtained in the same manner as in Synthesis Example 2, except that TnPA was weighed out so that the molar equivalent ratio of HPS to TnPA was 1.08.

[Synthesis Example 6]
(Synthesis of Neutralized Salt S-6)
A neutralized salt S-6 (3-hydroxypropanesulfonic acid tripropylamine salt) was obtained in the same manner as in Synthesis Example 2, except that TnPA was weighed out so that the molar equivalent ratio of HPS to TnPA was 1.13.

[Synthesis Example 7]
(Synthesis of Neutralized Salt S-7)
A neutralized salt S-7 (3-hydroxypropanesulfonic acid tripropylamine salt) was obtained in the same manner as in Synthesis Example 2, except that TnPA was weighed out so that the molar equivalent ratio of HPS to TnPA was 1.18.

[Synthesis Example 8]
(Synthesis of Neutralized Salt S-8)
A solution was obtained by adding 10 parts by mass of 1-propanol to 20 parts by mass of an 85% by mass aqueous solution of 4-hydroxybenzenesulfonic acid (hereinafter sometimes abbreviated as "HBS") and stirring. Furthermore, tributylamine (hereinafter sometimes abbreviated as "TBA") was weighed out so that the molar equivalent ratio of HBS to tributylamine was 1.08, and a liquid obtained by diluting with the same part by mass of 1-propanol was added dropwise to the solution under stirring. One hour after the start of the dropwise addition, stirring was stopped, and the mixture was dehydrated and desolvated in an evaporator to obtain neutralized salt S-8 (4-hydroxybenzenesulfonic acid tributylamine salt).

[Synthesis Example 9]
(Synthesis of Neutralized Salt S-9)
A neutralized salt S-9 (4-hydroxybenzenesulfonic acid tributylamine salt) was obtained in the same manner as in Synthesis Example 8, except that TBA was weighed out so that the molar equivalent ratio of HBS to TBA was 1.18.

[Synthesis Example 10]
(Synthesis of Neutralized Salt S-10)
10 parts by mass of 1-propanol was added to 20 parts by mass of an 80% by mass aqueous solution of HPS and stirred to obtain a solution. Furthermore, N,N-didimethylcyclohexamine (hereinafter sometimes abbreviated as "DMCHA") was weighed out so that the molar equivalent ratio of HPS to DMCHA was 1.02, and a liquid diluted with the same part by mass of 1-propanol was added dropwise to the solution under stirring. Stirring was stopped one hour after the start of the dropwise addition, and the mixture was dehydrated and desolvated with an evaporator to obtain a neutralized salt S-10 (3-hydroxypropanesulfonic acid N,N-didimethylcyclohexamine salt).

[Synthesis Example 11]
(Synthesis of Neutralized Salt S-11)
10 parts by mass of 1-propanol was added to 20 parts by mass of an 80% by mass HES aqueous solution and stirred to obtain a solution. Furthermore, DMCHA was weighed out so that the molar equivalent ratio of HES to DMCHA was 1.02, and the same part by mass of 1-propanol was diluted and added dropwise to the stirred solution. Stirring was stopped one hour after the start of the dropwise addition, and the mixture was dehydrated and desolvated with an evaporator to obtain a neutralized salt S-11 (3-hydroxyethanesulfonic acid N,N-dimethylcyclohexylamine salt).

[Synthesis Example 12]
(Synthesis of Neutralized Salt S-12)
20 parts by mass of an 80% by mass aqueous solution of HPS and 10 parts by mass of 1-propanol were added and stirred to obtain a solution. Furthermore, N,N-diisopropylethylamine (hereinafter sometimes abbreviated as "DIPEA") was weighed out so that the molar equivalent ratio of HPS to DIPEA was 1.02, and the same part by mass of DIPEA was diluted with 1-propanol and added dropwise to the solution under stirring. Stirring was stopped one hour after the start of the dropwise addition, and the mixture was dehydrated and desolvated with an evaporator to obtain a neutralized salt S-12 (3-hydroxypropanesulfonic acid N,N-diisopropylethylamine salt) with a solid content of 99.5% by mass.

[Synthesis Example 13]
(Synthesis of Neutralized Salt S-13)
A neutralized salt S-13 (3-hydroxypropanesulfonic acid N,N-diisopropylethylamine salt) was obtained in the same manner as in Synthesis Example 12, except that DIPEA was weighed out so that the molar equivalent ratio of HPS to DIPEA was 1.13.

[Synthesis Example 14]
(Synthesis of Neutralized Salt S-14)
10 parts by mass of 1-propanol was added to 20 parts by mass of a 70% by mass HES aqueous solution and stirred to obtain a solution. Furthermore, N-methylpyrrolidine was weighed out so that the molar equivalent ratio of HES to N-methylpyrrolidine was 1.02, and the solution was diluted with the same part by mass of 1-propanol and added dropwise to the stirred solution. Stirring was stopped one hour after the start of the dropwise addition, and the mixture was dehydrated and desolvated with an evaporator to obtain a neutralized salt S-14 (2-hydroxyethanesulfonic acid N-methylpyrrolidine salt).

[Synthesis Example 15]
(Synthesis of Neutralized Salt S-15)
A neutralized salt S-15 (2-hydroxyethanesulfonic acid N,N-didimethylcyclohexamine salt) was obtained in the same manner as in Synthesis Example 11, except that DMCHA was weighed out so that the molar equivalent ratio of HES to DMCHA was 1.33.

[Synthesis Example 16]
(Synthesis of Neutralized Salt S-16)
A neutralized salt S-16 (3-hydroxypropanesulfonic acid tributylamine salt) was obtained in the same manner as in Synthesis Example 9, except that TBA was weighed out so that the molar equivalent ratio to HPS was 1.00.

<Synthesis of Polyisocyanate>
[Synthesis Example 17]
(Synthesis of Polyisocyanate P-1)
A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen blowing tube, and a dropping funnel was conditioned with nitrogen, 1000 g of HDI and 4.0 g of isobutanol were charged, and the temperature inside the reactor was maintained at 70° C. under stirring. Tetramethylammonium caprylate was added thereto, and when the yield reached 25%, phosphoric acid was added to stop the reaction. The reaction liquid was then filtered, and unreacted HDI was removed using a thin-film evaporator to obtain polyisocyanate P-1. The viscosity of the obtained polyisocyanate P-1 at 25° C. was 1500 mPa·s, and the isocyanate group content was 23.1% by mass.

[Synthesis Example 18]
(Synthesis of Polyisocyanate P-2)
Polyisocyanate P-2 was obtained in the same manner as in Synthesis Example 17, except that phosphoric acid was added to terminate the reaction when the yield reached 50%. The viscosity of the obtained polyisocyanate P-2 at 25° C. was 2700 mPa s, and the isocyanate group content was 21.7% by mass.

<Production of polyisocyanate composition>
[Example 1]
(Production of polyisocyanate composition PA-1a)
To 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 17, 4.09 parts by mass (0.035 mol) of hydroxypivalic acid and 6.11 parts by mass (0.033 mol) of TBA were added, and the mixture was stirred at 100° C. for 5 hours under reflux in a nitrogen atmosphere to produce a polyisocyanate composition PA-1a.

[Example 2]
(Production of polyisocyanate composition PA-2a)
To 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 17, 5.94 parts by mass (0.038 mol) of 4-(hydroxymethyl)cyclohexanecarboxylic acid and 6.62 parts by mass (0.036 mol) of TBA were added, and the mixture was stirred at 100° C. for 5 hours under reflux in a nitrogen atmosphere to produce a polyisocyanate composition PA-2a.

[Example 3]
(Production of polyisocyanate composition PA-3a)
To 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 17, 4.51 parts by mass (0.032 mol) of 2-hydroxyethyl phosphate and 5.60 parts by mass (0.030 mol) of TBA were added, and the mixture was stirred at 100° C. for 5 hours under reflux in a nitrogen atmosphere to produce a polyisocyanate composition PA-3a.

[Example 4]
(Production of polyisocyanate composition PA-4a)
To 100 parts by mass of polyisocyanate P-1 obtained in Synthesis Example 17, 5.30 parts by mass of 2-hydroxyethanesulfonic acid/sodium salt (HES/Na) of neutralized salt S-1 obtained in Synthesis Example 1 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-4a.

[Example 5]
(Production of polyisocyanate composition PA-5a)
To 100 parts by mass of polyisocyanate P-2 obtained in Synthesis Example 18, 7.87 parts by mass of 3-hydroxypropanesulfonic acid tripropylamine salt (HPS/TnPA) of neutralized salt S-2 obtained in Synthesis Example 2 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-5a.

[Example 6]
(Production of polyisocyanate composition PA-6a)
A polyisocyanate composition PA-6a was produced in the same manner as in Example 5, except that 7.89 parts by mass of the 3-hydroxypropanesulfonic acid tripropylamine salt (HPS/TnPA) of the neutralized salt S-3 obtained in Synthesis Example 3 was added instead of the neutralized salt S-2 obtained in Synthesis Example 2.

[Example 7]
(Production of polyisocyanate composition PA-7a)
A polyisocyanate composition PA-7a was produced in the same manner as in Example 5, except that 7.93 parts by mass of the 3-hydroxypropanesulfonic acid tripropylamine salt (HPS/TnPA) of the neutralized salt S-4 obtained in Synthesis Example 4 was added instead of the neutralized salt S-2 obtained in Synthesis Example 2.

[Example 8]
(Production of polyisocyanate composition PA-8a)
A polyisocyanate composition PA-8a was produced in the same manner as in Example 5, except that 8.16 parts by mass of the 3-hydroxypropanesulfonic acid tripropylamine salt (HPS/TnPA) of the neutralized salt S-5 obtained in Synthesis Example 5 was added instead of the neutralized salt S-2 obtained in Synthesis Example 2.

[Example 9]
(Production of polyisocyanate composition PA-9a)
A polyisocyanate composition PA-9a was produced in the same manner as in Example 5, except that 8.35 parts by mass of the 3-hydroxypropanesulfonic acid tripropylamine salt (HPS/TnPA) of the neutralized salt S-6 obtained in Synthesis Example 6 was added instead of the neutralized salt S-2 obtained in Synthesis Example 2.

[Example 10]
(Production of polyisocyanate composition PA-10a)
A polyisocyanate composition PA-10a was produced in the same manner as in Example 5, except that 8.54 parts by mass of the 3-hydroxypropanesulfonic acid tripropylamine salt (HPS/TnPA) of the neutralized salt S-7 obtained in Synthesis Example 7 was added instead of the neutralized salt S-2 obtained in Synthesis Example 2.

[Example 11]
(Production of polyisocyanate composition PA-11a)
To 100 parts by mass of polyisocyanate P-1 obtained in Synthesis Example 17, 10.57 parts by mass of 4-hydroxybenzenesulfonic acid tributylamine salt (HBS/TBA) of S-8 obtained in Synthesis Example 8 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-11a.

[Example 12]
(Production of polyisocyanate composition PA-12a)
To 100 parts by mass of polyisocyanate P-2 obtained in Synthesis Example 18, 9.00 parts by mass of 3-hydroxypropanesulfonic acid tributylamine salt (HPS/TBA) of the neutralized salt S-10 of S-9 obtained in Synthesis Example 9 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-12a.

[Example 13]
(Production of polyisocyanate composition PA-13a)
To 100 parts by mass of polyisocyanate P-1 obtained in Synthesis Example 17, 9.58 parts by mass of 3-hydroxypropanesulfonic acid N,N-dimethylcyclohexylamine salt (HES/DMCHA) of the neutralized salt S-10 obtained in Synthesis Example 10 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-13a.

[Example 14]
(Production of polyisocyanate composition PA-14a)
A polyisocyanate composition PA-14a was produced in the same manner as in Example 13, except that 9.14 parts by mass of the 2-hydroxyethanesulfonic acid N,N-dimethylcyclohexylamine salt (HES/DMCHA) of the neutralized salt S-11 obtained in Synthesis Example 11 was added instead of the neutralized salt S-10 obtained in Synthesis Example 10.

[Example 15]
(Production of polyisocyanate composition PA-15a)
To 100 parts by mass of polyisocyanate P-2 obtained in Synthesis Example 18, 8.37 parts by mass of 3-hydroxypropanesulfonic acid N,N-diisopropylethylamine salt (HPS/DIPEA) of neutralized salt S-12 obtained in Synthesis Example 12 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-15a.

[Example 16]
(Production of polyisocyanate composition PA-16a)
A polyisocyanate composition PA-16a was produced in the same manner as in Example 15, except that 8.84 parts by mass of the 3-hydroxypropanesulfonic acid N,N-diisopropylethylamine salt (HPS/DIPEA) of the neutralized salt S-13 obtained in Synthesis Example 13 was added instead of the neutralized salt S-12 obtained in Synthesis Example 12.

[Example 17]
(Production of polyisocyanate composition PA-17a)
A polyisocyanate composition PA-17a was produced in the same manner as in Example 15, except that 6.07 parts by mass of 2-hydroxyethanesulfonic acid N-methylpyrrolidine salt (hereinafter, "HES/N-methylpyrrolidine") of S-14 obtained in Synthesis Example 14 was added instead of the neutralized salt S-12 obtained in Synthesis Example 12.

[Example 18]
(Production of polyisocyanate composition PA-18a)
To 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 17, 5.81 parts by mass (0.028 mol) of 2-cyclohexylaminoethanesulfonic acid (hereinafter, may be abbreviated as "CAES") and 3.50 parts by mass (0.027 mol) of DMCHA were added, and the mixture was stirred at 100°C for 5 hours under reflux in a nitrogen atmosphere to produce a polyisocyanate composition PA-18a.

[Example 19]
(Production of polyisocyanate composition PA-19a)
To 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 17, 7.05 parts by mass (0.030 mol) of 4-cyclohexylaminobutanesulfonic acid (hereinafter, may be abbreviated as "CABS") and 5.09 parts by mass (0.027 mol) of TBA were added, and the mixture was stirred at 100°C for 5 hours under reflux in a nitrogen atmosphere to produce a polyisocyanate composition PA-19a.

[Comparative Example 1]
(Production of polyisocyanate composition PA-1b)
To 100 parts by mass of polyisocyanate P-1 obtained in Synthesis Example 17, 8.11 parts by mass of 2-hydroxyethanesulfonic acid N,N-dimethylcyclohexylamine salt (HES/DMCHA) of S-15 obtained in Synthesis Example 15 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-1b.

[Comparative Example 2]
(Production of polyisocyanate composition PA-2b)
To 100 parts by mass of the polyisocyanate P-1 obtained in Synthesis Example 17, 8.96 parts by mass (0.038 mol) of CABS and 3.85 parts by mass (0.030 mol) of DMCHA were added, and the mixture was stirred at 100° C. for 5 hours under reflux in a nitrogen atmosphere to produce a polyisocyanate composition PA-2b.

[Comparative Example 3]
(Production of polyisocyanate composition PA-3b)
To 100 parts by mass of polyisocyanate P-2 obtained in Synthesis Example 18, 8.35 parts by mass of 3-hydroxypropanesulfonic acid tributylamine salt (HPS/TBA) of S-16 obtained in Synthesis Example 16 was added, and the mixture was reacted under nitrogen and reflux with stirring at 120° C. for 3 hours. Thereafter, the reflux was removed and the reaction was continued with stirring at 100° C. for 1 hour to produce polyisocyanate composition PA-3b.

The physical properties of the polyisocyanate compositions obtained in the Examples and Comparative Examples were measured using the methods described above. The results are shown in Tables 1 to 4. The obtained polyisocyanate compositions were also evaluated using the methods described above. The results are shown in Tables 1 to 4.

As seen from Tables 1 to 3, the polyisocyanate compositions PA-1a to PA-19a (Examples 1 to 19) having a molar ratio of hydrophilic anion group/cationic compound of 1.005 or more and 1.18 or less had good transparency, and when formed into a coating film, the appearance and water resistance were also good.
In a comparison of polyisocyanate compositions PA-1a to PA-3a and PA-11a (Examples 1 to 3 and 11) containing different types of anionic compounds, the polyisocyanate compositions PA-1a to PA-2a in which the anionic compounds were hydroxypivalic acid, 4-(hydroxymethyl)cyclohexanecarboxylic acid and hydroxybenzenesulfonic acid tended to have a more excellent appearance when formed into a coating film, while the polyisocyanate composition PA-11a in which the anionic compound was hydroxybenzenesulfonic acid tended to have a more excellent transparency, and a more excellent appearance and water resistance when formed into a coating film.
In a comparison of polyisocyanate compositions PA-9a and PA-16a (Examples 9 and 16) containing different types of cationic compounds, the polyisocyanate composition PA-9a, in which the cationic compound is an amine compound having a linear alkyl group, tended to have a more excellent appearance when formed into a coating film.
In a comparison of the polyisocyanate compositions PA-5a to PA-10a having different molar ratios of hydrophilic anionic group/cationic compound, when the molar ratio of hydrophilic anionic group/cationic compound was 1.005 or more and 1.08 or less, the transparency tended to be better, when the molar ratio of hydrophilic anionic group/cationic compound was 1.13 or less, the appearance of the coating film tended to be better, and when the molar ratio of hydrophilic anionic group/cationic compound was 1.01 or more, the water resistance of the coating film tended to be better.
In comparison between polyisocyanate compositions PA-a13 and PA-a14, which use a neutralized salt of an anionic compound and a cationic compound, and a case in which an anionic compound and a cationic compound are used as separate compounds, the polyisocyanate compositions PA-a13 and PA-a14, which use a neutralized salt of an anionic compound and a cationic compound, tend to have better appearance and water resistance when formed into a coating film.

On the other hand, from Table 4, polyisocyanate compositions PA-1b and PA-2b (Comparative Examples 1 and 2) in which the molar ratios of hydrophilic anion group/cationic compound were 1.33 and 1.26, respectively, had poor transparency, and the appearance and water resistance of the coating film were also poor. Also, polyisocyanate composition PA-3b (Comparative Example 3) in which the molar ratio of hydrophilic anion group/cationic compound was 1.00 had good transparency and good appearance of the coating film, but poor water resistance of the coating film.

The polyisocyanate composition of this embodiment has high transparency and excellent appearance and water resistance when formed into a coating film.

Claims (9)

A polyisocyanate having in its molecule at least one hydrophilic anion group selected from the group consisting of a carboxylate anion group, a phosphate anion group, and a sulfonate anion group;
a cationic compound,
a molar ratio of the hydrophilic anion group to the cationic compound is 1.002 or more and 1.2 or less;
The cationic compound is a tertiary ammonium cation of an amine compound represented by the following general formula (1):
The polyisocyanate containing a hydrophilic anion group in the molecule is obtained by reacting an amine salt of a sulfonic acid having a hydroxyl group with a polyisocyanate, and
The polyisocyanate composition , wherein the amine salt of a sulfonic acid having a hydroxyl group is a salt of a sulfonic acid having a hydroxyl group and an amine compound represented by general formula (1).

(In general formula (1), R ¹¹ , R ¹² and R ¹³ are each independently a hydrocarbon group having 1 to 10 carbon atoms which may contain an ether bond. At least one selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may contain a ring structure, and two or more selected from the group consisting of R ¹¹ , R ¹² and R ¹³ may be bonded to each other to form a ring structure. The ring structure is an aromatic ring, a cycloalkyl group having 5 or 6 carbon atoms, a 5- or 6-membered ring in which R ¹¹ and R ¹² are bonded to each other, or a multi-membered multiple ring in which R ¹¹ , R ¹² and R ¹³ are bonded to each other.) The polyisocyanate composition according to claim 1, wherein the molar ratio of the hydrophilic anion group to the cationic compound is 1.01 or more and 1.1 or less. The polyisocyanate composition according to claim 1 or 2, wherein the hydrophilic anion group includes a sulfonate anion group. The polyisocyanate composition according to any one of claims 1 to 3 , wherein the amine compound represented by the general formula (1) includes an amine compound in which R ¹¹ , R ¹² , and R ¹³ are all linear aliphatic hydrocarbon groups. The polyisocyanate composition according to claim 1 , wherein the sulfonic acid having a hydroxyl group is a compound represented by the following general formula (2):

(In general formula (2), ^R21 is a hydrocarbon group having 1 to 10 carbon atoms which may contain at least one selected from the group consisting of a hydroxyl group, an ether bond, an ester bond, a carbonyl group, and an imino group. ^R21 may contain a ring structure. The ring structure is an aromatic ring, a 5- or 6-membered ring containing two nitrogen atoms, or a 5- or 6-membered ring containing a nitrogen atom and an oxygen atom.) The polyisocyanate composition according to any one of claims 1 to 5 , wherein the polyisocyanate has an isocyanurate group. The polyisocyanate composition according to any one of claims 1 to 6 , wherein the polyisocyanate is at least one selected from the group consisting of aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. A coating composition comprising the polyisocyanate composition according to any one of claims 1 to 7 . A coated substrate coated with the coating composition according to claim 8 .