JP2019014777A - Polyisocyanate composition, dilution solution of polyisocyanate composition, coating composition and coating film - Google Patents

Abstract

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【選択図】なしDisclosed is a polyisocyanate composition that is excellent in storage stability at high and low temperatures when diluted with a solvent, and that provides a water-resistant coating film.
A polyisocyanate composition comprises a polyisocyanate obtained from one or more diisocyanates selected from the group consisting of aliphatic diisocyanates containing 1,6-diisocyanatohexane and alicyclic diisocyanates containing isophorone diisocyanate. It contains isocyanate and one or more types of triisocyanate represented by the following general formula (I), and the mass ratio of the polyisocyanate to the triisocyanate is from 100 / 5.0 to 100 / 0.01.
[Chemical 1]

... (I)
[Selection figure] None

Description

  The present invention relates to a polyisocyanate composition, a dilute solution of a polyisocyanate composition, a coating composition, and a coating film.

  Conventionally, a urethane coating film formed from a polyurethane paint has very excellent flexibility, chemical resistance, and stain resistance. In particular, it is represented by an aliphatic diisocyanate represented by 1,6-diisocyanatohexane (hereinafter sometimes referred to as “HDI”) or by an isophorone diisocyanate (hereinafter sometimes represented by “IPDI”). Urethane coatings using non-yellowing polyisocyanates obtained from alicyclic polyisocyanates as curing agents are further excellent in weather resistance, and their demand is increasing.

 Moreover, when preparing the coating composition using the said polyisocyanate as a hardening | curing agent, the said polyisocyanate may be diluted with a solvent beforehand and used from the workability | operativity. At that time, when the amount of water in the solvent used is large, the isocyanate group of the polyisocyanate reacts with water to cause gelation, turbidity, and the like. As a countermeasure, a technique of adding a dehydrating agent such as p-toluenesulfonyl isocyanate or methyl orthoformate to a solvent to be used or polyisocyanate is disclosed (for example, see Patent Document 1).

JP 2006-36807 A

However, in the technique described in Patent Document 1, when the polyisocyanate is stored as a diluted solution containing a solvent and a dehydrating agent, the added dehydrating agent may cause coloration or turbidity at low temperatures. It was.
In addition, there is a method of use after reducing the water content of the solvent in advance by treating the solvent used for dilution with a dehydrating agent such as precision distillation or molecular sieve in advance. However, since the above treatment is costly, a polyisocyanate composition that can provide a coating film having excellent storage stability after dilution and excellent water resistance even when a solvent containing water is used as a diluent solvent is anxious. It had been.

  The present invention has been made in view of the above circumstances, and is a polyisocyanate composition from which a coating film having excellent storage stability at high and low temperatures when diluted with a solvent and excellent in water resistance can be obtained. Offer things. The present invention also provides a dilute solution of the polyisocyanate composition containing the polyisocyanate composition and having excellent storage stability at high temperatures and low temperatures. Moreover, the coating composition which contains the diluted solution of the said polyisocyanate composition and can obtain the coating film excellent in water resistance is provided. Moreover, the coating film obtained from the said coating composition and excellent in water resistance is provided.

That is, the present invention includes the following aspects.
The polyisocyanate composition according to the first aspect of the present invention is one or more diisocyanates selected from the group consisting of aliphatic diisocyanates containing 1,6-diisocyanatohexane and alicyclic diisocyanates containing isophorone diisocyanate. And a polyisocyanate represented by the following general formula (I), wherein a mass ratio of the polyisocyanate to the triisocyanate is from 100 / 5.0 to 100 / 0.01 It is.

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... (I)

[In General Formula (I), a plurality of Y ¹ are each independently a single bond, or a divalent group having 1 to 20 carbon atoms that may contain one or more selected from the group consisting of an ester structure and an ether structure. It is a hydrocarbon group. A plurality of Y ¹ may be the same or different. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. ]
In the polyisocyanate composition according to the first aspect, one or more of Y ^{1 in} the triisocyanate may include an ester structure.

  The dilute solution of the polyisocyanate composition according to the second aspect of the present invention includes the polyisocyanate composition according to the first aspect and a volatile organic solvent, and the polyisocyanate and the triisol with respect to the volatile organic solvent. The mass ratio of the total amount of isocyanate is 5/95 or more and 95/5 or less.

  The coating composition which concerns on the 3rd aspect of this invention contains the diluted solution of the polyisocyanate composition which concerns on the said 2nd aspect, and a polyol.

  The coating film according to the fourth aspect of the present invention is obtained by curing the coating composition according to the third aspect.

  According to the said aspect, the polyisocyanate composition from which the coating film excellent in the storage stability in the time of high temperature and low temperature at the time of diluting with a solvent and excellent in water resistance can be obtained can be provided. In addition, it is possible to provide a dilute solution of a polyisocyanate composition that contains the polyisocyanate composition and has excellent storage stability at high temperatures and low temperatures. Moreover, the coating composition which contains the diluted solution of the said polyisocyanate composition and can obtain the coating film excellent in water resistance can be provided. Moreover, the coating film obtained from the said coating composition and excellent in water resistance can be provided.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

In the present specification, “polyisocyanate” means a reaction product in which a plurality of monomer compounds having one or more isocyanate groups (—NCO) are bonded.
In this specification, “polyol” means a compound having two or more hydroxy groups (—OH).
In this specification, unless otherwise specified, “(meth) acryl” includes methacryl and acryl, and “(meth) acrylate” includes methacrylate and acrylate.

≪Polyisocyanate composition≫
A polyisocyanate composition according to an embodiment of the present invention includes an aliphatic diisocyanate containing 1,6-diisocyanatohexane (hereinafter sometimes referred to as “HDI”), and an isophorone diisocyanate (hereinafter referred to as “IPDI”). A polyisocyanate obtained from one or more diisocyanates selected from the group consisting of alicyclic diisocyanates, and one or more triisocyanates represented by the following general formula (I): The mass ratio of the polyisocyanate to the triisocyanate is 100 / 5.0 or more and 100 / 0.01 or less.

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... (I)

[In General Formula (I), a plurality of Y ¹ are each independently a single bond, or a divalent group having 1 to 20 carbon atoms that may contain one or more selected from the group consisting of an ester structure and an ether structure. It is a hydrocarbon group. A plurality of Y ¹ may be the same or different. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. ]

  The polyisocyanate composition of the present embodiment includes a polyisocyanate and a triisocyanate, and the mass ratio of the polyisocyanate to the triisocyanate is 100 / 5.0 or more and 100 / 0.01 or less. When the product is diluted with a solvent, it has excellent storage stability at both high and low temperatures. Furthermore, the coating film obtained from the coating composition containing the polyisocyanate composition of this embodiment has excellent water resistance.

In the present specification, “storage stability” means a property in which appearance changes such as gelation and coloring are less likely to occur when a dilute solution of a polyisocyanate composition is stored at high or low temperatures.
Details of each component constituting the polyisocyanate composition of the present embodiment will be described below.

<Polyisocyanate>
The polyisocyanate contained in the polyisocyanate composition of the present embodiment is obtained by reacting a plurality of one or more diisocyanates selected from the group consisting of aliphatic diisocyanates containing HDI and alicyclic diisocyanates containing IPDI. It is a reactant. The polyisocyanate may be a reaction product obtained by reacting one kind of the above-mentioned diisocyanate, or a reaction product obtained by reacting two or more kinds of the above-mentioned diisocyanate. The polyisocyanate may be a mixture of the reactants.
Especially, it is preferable that the polyisocyanate contained in the polyisocyanate composition of this embodiment is a polyisocyanate obtained from HDI from the reactivity at the time of manufacture of a polyisocyanate.

The aliphatic diisocyanate preferably has 4 to 30 carbon atoms. For example, 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, HDI, 2,2,4-trimethyl-1,6- Examples include diisocyanatohexane, 2-methylpentane-1,5-diisocyanate (MPDI), and lysine diisocyanate. These aliphatic diisocyanates may be used alone or in combination of two or more.
Of these, HDI is preferred as the aliphatic diisocyanate because of its industrial availability.

The alicyclic diisocyanate preferably has 8 to 30 carbon atoms, and examples thereof include IPDI, 1,3-bis (isocyanatomethyl) -cyclohexane, 4,4′-dicyclohexylmethane diisocyanate, and norbornene diisocyanate. These alicyclic diisocyanates may be used alone or in combination of two or more.
Among these, as the alicyclic diisocyanate, IPDI is preferable because of the weather resistance of the resulting coating film and industrial availability.

  The polyisocyanate contained in the polyisocyanate composition of the present embodiment preferably includes an isocyanurate structure. Here, the “isocyanurate structure” is a polyisocyanate composed of three diisocyanate molecules, and is represented by the following formula (II).

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... (II)

Examples of the method for producing polyisocyanate include a method using an isocyanurate-forming catalyst.
As the isocyanurate-forming catalyst, for example, those having basicity are generally preferred, and examples thereof are shown below.
(1) Tetraalkylammonium hydroxide (eg, tetramethylammonium, tetraethylammonium, etc.), hydroxyalkylammonium hydroxide (eg, trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium, triethylhydroxyethylammonium, etc.) ), Organic weak acid salts such as acetic acid and capric acid.
(2) Alkali metal (eg, tin, zinc, lead, etc.) salts of alkyl carboxylic acids (eg, acetic acid, caproic acid, octylic acid, myristic acid, etc.).
(3) Metal alcoholates such as sodium and potassium.
(4) Aminosilyl group-containing compounds such as hexamethyldisilazane.
(5) Mannich bases.
(6) Combined use of tertiary amines and epoxy compounds.
(7) Phosphorus compounds such as tributylphosphine.

  Among them, as the isocyanurate-forming catalyst, an organic weak acid salt of quaternary ammonium is preferable, and an organic weak acid salt of tetraalkylammonium is more preferable.

Moreover, it is preferable to stop the reaction after the isocyanuration reaction. Examples of the method for stopping the reaction include a method for deactivating the catalyst. Examples of the method for deactivating the catalyst include neutralization with an acidic substance such as phosphoric acid and acidic phosphoric acid ester, thermal decomposition, chemical decomposition, and the like.

  Further, the polyisocyanate contained in the polyisocyanate composition of the present embodiment includes a uretdione structure (structure represented by the following formula (III)) and an iminooxadiazinedione structure (structure represented by the following formula (IV)). , Allophanate structure (structure represented by the following formula (V)), urethane structure (structure represented by the following formula (VI)), or burette structure (structure represented by the following formula (VII)) Good.

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... (III)

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... (IV)

・・・（Ｖ）

... (V)

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... (VI)

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... (VII)

In the polyisocyanate contained in the polyisocyanate composition of the present embodiment, the upper limit value of the diisocyanate monomer content is preferably 1% by mass or less, and 0.5% by mass or less, based on the total mass of the polyisocyanate. Is more preferably 0.3% by mass or less, and particularly preferably 0.2% by mass or less. When the content of the diisocyanate monomer is not more than the above upper limit, it is possible to suppress a decrease in crosslinkability of the polyisocyanate composition of the present embodiment.
On the other hand, the lower limit of the content of the diisocyanate monomer is not particularly limited and may be, for example, 0% by mass or more.

[Physical properties of polyisocyanate]
(Viscosity at 25 ° C.)
The viscosity at 25 ° C. of the polyisocyanate contained in the polyisocyanate composition of the present embodiment is not particularly limited, but is preferably 100 mPa · s or more and 10,000 mPa · s or less, more preferably 150 mPa · s or more and 5000 mPa · s or less. It is preferably 200 mPa · s or more and 3000 mPa · s or less, and particularly preferably 200 mPa · s or more and 1500 mPa · s or less.
When the viscosity at 25 ° C. of the polyisocyanate is equal to or higher than the lower limit, it is possible to suppress a decrease in drying property when a coating film is formed using the polyisocyanate composition of the present embodiment. On the other hand, when the viscosity of the polyisocyanate at 25 ° C. is not more than the above upper limit, the amount of the solvent used for diluting the polyisocyanate composition of the present embodiment can be limited.
The viscosity at 25 ° C. can be measured by using an E-type viscometer (manufactured by Tokimec).

(Number average molecular weight)
The number average molecular weight of the solid content of the polyisocyanate contained in the polyisocyanate composition of the present embodiment is not particularly limited, but is preferably 400 or more and 1,500 or less, more preferably 440 or more and 1,200 or less. 480 or more and 1000 or less are more preferable, and 480 or more and 700 or less are particularly preferable.
By making the number average molecular weight of the solid content of polyisocyanate more than the said lower limit, the yield of the polyisocyanate composition of this embodiment improves further. On the other hand, by making the number average molecular weight of the solid content of the polyisocyanate not more than the above upper limit value, the underlying concealability of the obtained coating film is improved.
The number average molecular weight can be determined by gel permeation chromatography (GPC). Specifically, it can measure according to the method as described in an Example.

<Triisocyanate>
The triisocyanate contained in the polyisocyanate composition of the present embodiment is a compound represented by the above general formula (I) (hereinafter sometimes referred to as “triisocyanate (I)”).

[Y ¹ ]
In general formula (I), a plurality of Y ¹ are each independently a single bond or a divalent divalent having 1 to 20 carbon atoms that may contain one or more selected from the group consisting of an ester structure and an ether structure. It is a hydrocarbon group. A plurality of Y ¹ may be the same or different.

The divalent hydrocarbon group having 1 to 20 carbon atoms may be an aliphatic group or an aromatic group. The aliphatic group may be linear, branched or cyclic.
Examples of the linear or branched aliphatic group include alkanediyl groups (alkylene groups) and alkylidene groups.
Examples of the cyclic aliphatic group include a cycloalkylene group.
Examples of the aromatic group include an arylene group such as a phenylene group.

Table Examples of the divalent hydrocarbon group having the ester structure and one or more comprise carbon atoms which may 1 to 20 selected from the group consisting of ether structure in Y ^1, for example, by the following general formula (VIII) Group (hereinafter may be referred to as “group (VIII)”).
_{- (CH 2) n1 -X- (} CH 2) n2 - ··· (VIII)

In the group (VIII), a bond opposite to X of — (CH ₂ ) _n1 — is bonded to carbon (C) in the general formula (I), and is opposite to X of — (CH ₂ ) _n2 —. Are bonded to the NCO in the general formula (I). Further, it is an integer satisfying 1 ≦ n1 + n2 ≦ 20. That is, both n1 and n2 do not become 0, and n2 on the side bonded to the NCO is preferably 1 or more.
Especially, it is preferable that n1 and n2 are respectively independently the integers of 0-20, 0-4 are more preferable, and 0-2 are more preferable.
As a combination of n1 and n2, for example, a combination of n1 = 0 and n2 = 2, a combination of n1 = 2 and n2 = 2 is preferable.

  Moreover, in group (VIII), X is an ester structure or an ether structure. Especially, since reaction rate goes up, it is preferable that X is an ester structure.

Moreover, when one or more of Y ^{1 in} a plurality contain an ester structure, the storage stability of the diluted solution of the polyisocyanate composition of the present embodiment at a low temperature can be further improved.

[R ¹ ]
R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. The hydrocarbon group of R ^1, is not particularly limited, an alkyl group, an alkenyl group, an alkynyl group. Among these, as R ¹ , a hydrogen atom is preferable.

  Specific examples of the triisocyanate contained in the polyisocyanate composition of the present embodiment include, for example, 4-isocyanate methyl-1,8-octamethylene diisocyanate disclosed in International Publication No. 1996/17881 (Reference 1). (Hereinafter sometimes referred to as “NTI”) (molecular weight 251), 1,3,6-hexamethylene triisocyanate (hereinafter referred to as “HTI”) disclosed in JP-A-57-198760 (reference 2). (Molecular weight 209), bis (2-isocyanatoethyl) 2-isocyanatoglutarate (hereinafter referred to as “GTI”) disclosed in Japanese Examined Patent Publication No. 4-1033 (reference 3). (Molecular weight 311), lysine disclosed in JP-A-53-135931 (Reference 4) Polyisocyanate (hereinafter, sometimes referred to as "LTI") (molecular weight 267), and the like.

Especially, NTI, GTI, or LTI is preferable, and since one or more of Y ^{1 having} a plurality include an ester structure, GTI or LTI is more preferable. By containing these triisocyanates, the reactivity of isocyanate groups when the polyisocyanate composition of this embodiment is used as a curing agent for a coating composition can be further increased.

[Method for producing triisocyanate]
In the present embodiment, the triisocyanate (I) contained in the cross-linking agent mixture can be obtained by, for example, subjecting amines such as amino acid derivatives, ether amines, and alkyl triamines to isocyanate.
Examples of the amino acid derivative include 2,5-diaminovaleric acid, 2,6-diaminohexanoic acid, aspartic acid, glutamic acid and the like. Since these amino acid derivatives are diamine monocarboxylic acid or monoamine dicarboxylic acid, a triamine having an ester group can be obtained by esterifying the carboxyl group with an alkanolamine such as ethanolamine. The obtained triamine having an ester group can be converted to a triisocyanate containing an ester structure by phosgenation of an amine or the like.

  Examples of the ether amine include trade name “D403” of Mitsui Chemicals Fine, which is polyoxyalkylene triamine. These ether amines are triamines, and can be converted to triisocyanates having an ether structure by phosgenation of amines.

  Examples of the alkyltriamine include triisocyanatononane (4-aminomethyl-1,8-octanediamine). These alkyltriamines are triamines, and can be converted to triisocyanates containing only hydrocarbons by phosgenation of amines.

<Mass ratio of polyisocyanate to triisocyanate>
In the polyisocyanate composition of the present embodiment, the mass ratio of the polyisocyanate to the triisocyanate is not particularly limited, but is preferably 100 / 5.0 or more and 100 / 0.01 or less, and 100 / 4.0 or more and 100 or less. /0.05 or less is more preferable, 100 / 3.0 or more and 100 / 0.1 or less is more preferable, and 100 / 3.0 or more and 100 / 0.2 or less is particularly preferable.
When the mass ratio of the polyisocyanate to the triisocyanate is not less than the above lower limit, the water resistance of the obtained coating film can be further improved. On the other hand, when the polyisocyanate mass ratio of the polyisocyanate with respect to triisocyanate is not more than the above upper limit value, the polyisocyanate composition of the present embodiment is stored at both high temperature and low temperature when diluted with a solvent. Stability can be further improved.

<Diluted solution of polyisocyanate composition>
A dilute solution of a polyisocyanate composition according to an embodiment of the present invention includes the polyisocyanate composition described above and a volatile organic solvent, and a total amount of the polyisocyanate and the triisocyanate with respect to the volatile organic solvent. The mass ratio is 5/95 or more and 95/5 or less.

  The dilute solution of the polyisocyanate composition of the present embodiment is excellent in storage stability at both high temperature and low temperature.

  The diluted solution of the polyisocyanate composition of the present embodiment can be obtained by diluting the above-described polyisocyanate composition with a volatile organic solvent. Moreover, the workability | operativity in the case of manufacturing the below-mentioned coating composition is improved by including the volatile organic solvent in the diluted solution of the polyisocyanate composition of this embodiment.

<Volatile organic solvent>
The volatile organic solvent contained in the dilute solution of the polyisocyanate composition of the present embodiment is not particularly limited as long as it does not have a functional group that reacts with the hydroxyl group of the polyol and the isocyanate group of the polyisocyanate composition described below. Moreover, it is preferable that it is compatible with the above-mentioned polyisocyanate composition. The volatile organic solvent is not particularly limited as long as it is generally used as a coating solvent, and specific examples include ester compounds, ether compounds, ketone compounds, aromatic hydrocarbons, hydrocarbon solvents and the like. .
Among these, as the volatile organic solvent, an ester compound, an ether compound, a ketone compound, or an aromatic hydrocarbon is preferable from the viewpoint of compatibility with a compound having an isocyanurate structure and triisocyanate. From the viewpoint of environmental regulations, an ester compound or a ketone compound is preferable.

  The boiling point of the volatile organic solvent is preferably 60 ° C. or higher and 240 ° C. or lower, more preferably 70 ° C. or higher and 220 ° C. or lower, more preferably 80 ° C. or higher and 200 ° C. or lower, still more preferably 80 ° C. or higher and 180 ° C. or lower. A temperature of not higher than ° C is particularly preferred.

  The ester compound is preferably an ester compound having 3 to 9 carbon atoms. Specific examples of the ester compound include, but are not limited to, methyl acetate, ethyl acetate, butyl acetate, γ-butyrolactone, and methyl benzoate.

  The ether compound is preferably an ether compound having 2 to 9 carbon atoms. Specific examples of the ether compound include, but are not limited to, dimethyl ether, diethyl ether, methyl ethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and the like.

  The ketone compound is preferably a ketone compound having 2 to 6 carbon atoms. Specific examples of the ketone compound include, but are not limited to, acetone, methyl ethyl ketone, and the like.

  The aromatic hydrocarbon is preferably an aromatic hydrocarbon compound having 6 to 10 carbon atoms. Specific examples of the aromatic hydrocarbon include, but are not limited to, benzene, toluene, xylene, mesitylene, tetralin and the like.

<Mass ratio of total amount of polyisocyanate and triisocyanate to volatile organic solvent>
In the diluted solution of the polyisocyanate composition of the present embodiment, the mass ratio of the total amount of polyisocyanate and triisocyanate to the volatile organic solvent is preferably 5/95 or more and 95/5 or less, and preferably 10/90 or more and 90 / It is more preferably 10 or less, further preferably 20/80 or more and 80/20 or less, and particularly preferably 25/75 or more and 70/30 or less.
By setting the mass ratio of the total amount of polyisocyanate and triisocyanate to the volatile organic solvent to be not less than the above lower limit, the diluted solution of the polyisocyanate composition of this embodiment can be stored stably at both high temperature and low temperature. The sex can be further improved. On the other hand, workability | operativity can be improved further because the mass ratio of the total amount of polyisocyanate and triisocyanate with respect to a volatile organic solvent shall be below the said upper limit.

≪Paint composition≫
The coating composition which concerns on one Embodiment of this invention contains the dilution solution of the above-mentioned polyisocyanate composition, and a polyol.

The coating composition of this embodiment can obtain the coating film which has the outstanding water resistance by including the dilution solution of the above-mentioned polyisocyanate composition as a hardening | curing agent, and including a polyol as a resin component.
Details of each component contained in the coating composition of the present embodiment will be described below.

<Polyol>
Examples of the polyol contained in the coating composition of the present embodiment include polyester polyol, polyether polyol, acrylic polyol, polyolefin polyol, and fluorine polyol. Among them, as the polyol, acrylic polyol is preferable from the viewpoint of weather resistance, chemical resistance and hardness of the obtained coating film, and polyester polyol is preferable from the viewpoint of mechanical strength and oil resistance of the obtained coating film.

[Polyester polyol]
The polyester polyol can be obtained, for example, by subjecting a dibasic acid alone or a mixture of two or more kinds to a polyhydric alcohol alone or a mixture of two or more kinds.
Examples of the dibasic acid include succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, carboxylic acids such as isophthalic acid, terephthalic acid, and 1,4-cyclohexanedicarboxylic acid.
Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, trimethylolpropane, glycerin, and pentaerythritol. , 2-methylolpropanediol, ethoxylated trimethylolpropane and the like.

  As a specific method for producing the polyester polyol, for example, the above-mentioned components are mixed and heated at about 160 to 220 ° C. to perform the condensation reaction.

  Alternatively, for example, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone using a polyhydric alcohol can also be used as the polyester polyol.

  The polyester polyol obtained by the above-described production method can be modified using aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, compounds obtained from these, and the like. Among these, from the viewpoint of weather resistance and yellowing resistance of the obtained coating film, the polyester polyol is preferably modified using aliphatic diisocyanate, alicyclic diisocyanate, and compounds obtained therefrom.

  When the coating composition of the present embodiment contains a solvent having a high water content, a part of the carboxylic acid derived from the dibasic acid in the polyester polyol is left and neutralized with a base such as amine or ammonia. By doing so, the polyester polyol can be made into a water-soluble or water-dispersible resin.

[Polyether polyol]
The polyether polyol can be obtained, for example, using any one of the methods (1) to (3) below.
(1) A method of obtaining a polyether polyol by randomly or block-adding an alkylene oxide alone or a mixture to a polyvalent hydroxy compound alone or a mixture using a catalyst.
Examples of the catalyst include hydroxides (lithium, sodium, potassium, etc.), strong basic catalysts (alcolate, alkylamine, etc.), complex metal cyanide complexes (metal porphyrin, hexacyanocobaltate zinc complex, etc.) and the like. It is done.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide.
(2) A method of obtaining a polyether polyol by reacting an alkylene oxide with a polyamine compound.
As said polyamine compound, ethylenediamine etc. are mentioned, for example.
As said alkylene oxide, the thing similar to what was illustrated by (1) is mentioned.
(3) A method of obtaining so-called polymer polyols by polymerizing acrylamide or the like using the polyether polyols obtained in (1) or (2) as a medium.

Examples of the polyvalent hydroxy compound include the following.
(I) Diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol and the like.
(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 ribodesource.
(Iv) Disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, melibiose.
(V) Trisaccharides such as raffinose, gentianose, and meletitose.
(Vi) Tetrasaccharides such as stachyose.

[Acrylic polyol]
The acrylic polyol, for example, polymerizes only a polymerizable monomer having one or more active hydrogens in one molecule, or a polymerizable monomer having one or more active hydrogens in one molecule and, if necessary, It can be obtained by copolymerizing the polymerizable monomer and another monomer copolymerizable.

Examples of the polymerizable monomer having one or more active hydrogens in one molecule include the following. These may be used alone or in combination of two or more.
(I) Acrylic acid esters having active hydrogen such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 2-hydroxybutyl acrylate.
(Ii) Methacrylic acid having active hydrogen such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate Esters.
(Iii) (meth) acrylic acid esters having polyvalent active hydrogen such as (meth) acrylic acid monoesters of triols such as glycerin and trimethylolpropane.
(Iv) Monoethers of polyether polyols (for example, polyethylene glycol, polypropylene glycol, polybutylene glycol, etc.) and (meth) acrylic acid esters having the above active hydrogen.
(V) Adducts of glycidyl (meth) acrylate and monobasic acids (for example, acetic acid, propionic acid, p-tert-butylbenzoic acid, etc.).
(Vi) An adduct obtained by ring-opening polymerization of a lactone (for example, ε-caprolactam, γ-valerolactone, etc.) to the active hydrogen of the (meth) acrylic acid ester having the active hydrogen.

Examples of other monomers copolymerizable with the polymerizable monomer include the following. These may be used alone or in combination of two or more.
(I) Methyl acrylate, ethyl acrylate, isopropyl acrylate, acrylic acid-n-butyl, acrylic acid-2-ethylhexyl, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, methacrylic acid-n-butyl, methacrylic acid (Meth) acrylic acid esters such as isobutyl, methacrylic acid-n-hexyl, cyclohexyl methacrylate, lauryl methacrylate and glycidyl methacrylate.
(Ii) Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc.) and unsaturated amides (acrylamide, N-methylolacrylamide, diacetoneacrylamide, etc.).
(Iii) Vinyl monomers having a hydrolyzable silyl group such as vinyltrimethoxysilane, vinylmethyldimethoxysilane, and γ- (meth) acrylopropyltrimethoxysilane.
(Iv) Other polymerizable monomers such as styrene, vinyl toluene, vinyl acetate, acrylonitrile, and dibutyl fumarate.

  As a specific method for producing an acrylic polyol, for example, the above monomers are solution-polymerized in the presence of a known radical polymerization initiator such as a peroxide or an azo compound, and diluted with an organic solvent or the like as necessary. As a result, an acrylic polyol can be obtained.

  When the coating composition of the present embodiment contains a solvent having a large amount of water, it can be produced by a known method such as solution polymerization of the above monomers and conversion to an aqueous layer or emulsion polymerization. In that case, it is possible to impart water solubility or water dispersibility to the acrylic polyol by neutralizing an acidic moiety such as a carboxylic acid-containing monomer such as acrylic acid or methacrylic acid or a sulfonic acid-containing monomer with an amine or ammonia. it can.

[Polyolefin polyol]
Examples of the polyolefin polyol include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene having two or more hydroxyl groups, polyisoprene having two or more hydroxyl groups, and hydrogenated polyisoprene having two or more hydroxyl groups.
Further, the number of hydroxyl groups (hereinafter sometimes referred to as “average number of hydroxyl groups”) possessed by one statistical molecule of polyolefin polyol is preferably 2 or more.

[Fluorine polyol]
In this specification, “fluorine polyol” means a polyol containing fluorine in the molecule. Specific examples of the fluoropolyol include fluoroolefins, cyclovinyl ethers, hydroxys disclosed in JP-A-57-34107 (reference 5), JP-A-61-275111 (reference 6), and the like. Examples thereof include copolymers such as alkyl vinyl ethers and monocarboxylic acid vinyl esters.

[Hydroxyl value and acid value of polyol]
The hydroxyl value of the polyol is preferably 10 mgKOH / g or more and 200 mgKOH / g or less, more preferably 20 mgKOH / g or more and 200 mgKOH / g or less, and further preferably 30 mgKOH / g or more and 200 mgKOH / g or less.
Moreover, it is preferable that the acid value of a polyol is 0 mgKOH / g or more and 30 mgKOH / g or less.
The hydroxyl value and acid value can be measured according to JIS K1557.

[NCO / OH]
The molar equivalent ratio (NCO / OH) of the isocyanate group of the polyisocyanate composition to the hydroxyl group of the polyol is preferably 0.2 or more and 5.0 or less, more preferably 0.4 or more and 3.0 or less. More preferably, it is 5 or more and 2.0 or less. When the molar equivalent ratio is not less than the above lower limit value, it becomes possible to obtain a tougher coating film. When the molar equivalent ratio is not more than the above upper limit, the smoothness of the coating film can be further improved.

<Other components>
[Melamine curing agent]
In addition to the above-mentioned diluted solution of the polyisocyanate composition and the above-mentioned polyol, the coating composition of the present embodiment may further include a melamine-based curing such as a complete alkyl type, a methylol type alkyl, and an imino group type alkyl as necessary. An agent may be contained.

[Volatile organic solvent]
The coating composition of this embodiment contains a volatile organic solvent for adjusting the viscosity of the coating composition, in addition to the volatile organic solvent derived from the dilute solution of the polyisocyanate composition. Also good.
As a volatile organic solvent, the thing similar to what was illustrated in the dilution solution of the above-mentioned polyisocyanate composition is mentioned.

[Other components]
In addition to the dilute solution of the polyisocyanate composition and the polyol described above, the coating composition of the present embodiment further includes a catalyst, a pigment, and the like, as long as the effects of the present embodiment are not impaired depending on the purpose and application. , Various additives used in the technical field, such as leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, and surfactants.

  Any catalyst may be used as long as it accelerates the curing of the coating composition. Examples thereof include metal salts such as dibutyltin dilaurate, tin 2-ethylhexanoate, zinc 2-ethylhexanoate, and cobalt salt; triethylamine, pyridine, and methylpyridine. , Tertiary amines such as benzyldimethylamine, N, N-dimethylcyclohexylamine, N-methylpiperidine, pentamethyldiethylenetriamine, N, N′-endoethylenepiperazine, N, N′-dimethylpiperazine, and the like.

<Method for producing coating composition>
As a manufacturing method of the coating composition of this embodiment, the following methods etc. are mentioned, for example.
First, additives such as other resins, catalysts, pigments, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, surfactants and the like were added to polyols or solvent dilutions thereof as necessary. A dilute solution of the polyisocyanate composition described above is added as a curing agent. Next, if necessary, after adding a solvent to adjust the viscosity, the coating composition can be obtained by hand stirring or stirring using a stirring device such as Mazelar.

<Application>
The coating composition of the present embodiment can be used as a coating such as roll coating, curtain flow coating, spray coating, bell coating, and electrostatic coating.
In addition, the coating composition of the present embodiment is useful as a primer or top intermediate coating for materials such as metals (steel plates, surface-treated steel plates, etc.), plastics, wood, films, inorganic materials, and the like.
The coating composition of the present embodiment is, for example, a pre-coated metal including a rust-proof steel plate, a paint for imparting cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, etc. to a painted part of an automobile, etc. It is also useful.
Moreover, the coating composition of this embodiment is useful also as urethane raw materials, such as an adhesive agent, an adhesive, an elastomer, foam, a surface treating agent, for example.

≪Coating film≫
The coating film which concerns on one Embodiment of this invention hardens the above-mentioned coating composition.

The coating film of this embodiment is obtained by applying and curing the above-described coating composition using a known method such as roll coating, curtain flow coating, spray coating, bell coating, electrostatic coating or the like.
The coating film of this embodiment is excellent in water resistance.

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example and a comparative example, this invention is not limited at all by the following examples.

≪Evaluation item≫
In accordance with the method shown below, the dilute solution of the polyisocyanate composition produced in Examples and Comparative Examples, the coating composition containing the diluted solution of the polyisocyanate composition, and the coating film obtained by curing the coating composition About each physical property and each evaluation were performed.

<Physical property 1: viscosity>
The viscosity of each triisocyanate was measured at 25 ° C. using an E-type viscometer (manufactured by Tokimec). In the measurement, a standard rotor (1 ° 34 ′ × R24) was used. The number of revolutions was set as shown below.
100 rpm (when less than 128 mPa · s)
50 rpm (128 mPa · s or more and less than 256 mPa · s)
20 rpm (in the case of 256 mPa · s or more and less than 640 mPa · s)
10 rpm (in the case of 640 mPa · s or more and less than 1280 mPa · s)
5 rpm (when 1280 mPa · s or more and less than 2560 mPa · s)

  In addition, the non-volatile content of triisocyanate was investigated by the method described below, and the viscosity of the compound whose value was 98% by mass or more was measured as it was.

(Measurement method of nonvolatile content)
The residual amount when triisocyanate was heated at 105 ° C. for 3 hours was measured, and the nonvolatile content was calculated using the following formula [A].
Nonvolatile content (mass%)
= (Mass of triisocyanate after heating at 105 ° C. for 3 hours) / (mass of triisocyanate before heating) × 100 (A)

<Physical property 2: Number average molecular weight of polyisocyanate>
The number average molecular weight of the polyisocyanate blended in the polyisocyanate composition was determined from the polystyrene-based number average molecular weight by gel permeation chromatography (hereinafter referred to as “GPC”) measurement using the following apparatus.
Equipment: “HLC-8120GPC (trade name)” manufactured by Tosoh Corporation
Column: "TSKgel SuperH1000 (trade name)" manufactured by Tosoh Corporation x 1
"TSKgel SuperH2000 (trade name)" x 1
"TSKgel SuperH3000 (trade name)" x 1 Carrier: Tetrahydrofuran Detection method: Differential refractometer Sample concentration: 5 wt / vol%
Carrier: THF
Detection method: Parallax refractometer Outflow amount: 0.6 mL / min
Column temperature: 30 ° C

<Physical property 3: NCO content>
The NCO content of the polyisocyanate composition was determined by back titration with 1N hydrochloric acid after neutralizing the isocyanate groups in the measurement sample with excess 2N amine. In addition, the non volatile matter of each polyisocyanate composition was investigated by the method mentioned above, and the thing whose value was 98 mass% or more was measured as it was.

<Evaluation 1: Storage stability (appearance after 40 ° C. × 10 days)>
The diluted solution of the polyisocyanate composition produced in Examples and Comparative Examples was sealed in a 100 mL glass bottle, and the state of the coating solution stored at 40 ° C. for 10 days was visually observed. As evaluation criteria, gelled ones were evaluated as x, turbidity was observed as Δ, and no change was observed as ◯.

<Evaluation 2: Storage stability (appearance after 0 degreeC x 10 days)>
The dilute solution of the polyisocyanate composition produced in Examples and Comparative Examples was sealed in a 100 mL glass bottle, stored at 0 ° C. for 10 days, and the state of the coating solution allowed to stand at 23 ° C. for 2 hours was visually observed. As evaluation criteria, gelled ones were evaluated as x, turbidity was observed as Δ, and no change was observed as ◯.

<Evaluation 3: Storage stability (color change)>
The dilute solution of the polyisocyanate composition produced in Examples and Comparative Examples was sealed in a 100 mL glass bottle and stored at 40 ° C. for 10 days. The chromaticity of the obtained coating liquid was evaluated according to ISO 6271. As evaluation criteria, the case where the difference in APHA value between storage and the initial stage was 50 or more was evaluated as x, the case of 30 or more and less than 50 was Δ, the case of 15 or more and less than 30 was ◯, and the case of less than 15 was rated ◎.

<Evaluation 4: Water resistance test of coating film>
The coating films obtained in Examples and Comparative Examples were put into a unicool adjusted to a temperature of 85 ° C. and a humidity of 85% for 100 hours, and the state of the coating film after being taken out was visually evaluated. As the evaluation criteria, the coating film after the test was marked with x when it was found to be blistered or swollen, Δ when the film was partially whitened, and ◯ when it was not changed.
Here, the “butsu” means a portion that has a protruding shape (convex shape) due to the presence of foreign matter or the like in the coating film.

[Synthesis Example 1] Synthesis of NTI (Triisocyanate (T-1)) 4-Isocyanatemethyl-1,8-octamethylenediamine was phosgenated in the presence of a solvent, cooled, filtered, and distilled under reduced pressure. Triisocyanate (T-1)) was obtained. The viscosity of the obtained triisocyanate (T-1) was 5 mPa · s / 25 ° C.

[Synthesis Example 2] Synthesis of LTI (Triisocyanate (T-2)) Lysine hydrochloride and ethanolamine were reacted in the presence of a solvent, methanol and the like were added, and then recrystallized to produce lysine β-aminoester trihydrochloride. Got. Next, lysine β-aminoester trihydrochloride was phosgenated in the presence of a solvent, filtered after cooling, and distilled under reduced pressure to obtain LTI (triisocyanate (T-2)). The viscosity of the obtained triisocyanate (T-2) was 25 mPa · s / 25 ° C.

[Synthesis Example 3] Synthesis of GTI (triisocyanate (T-3)) Glutamate hydrochloride and ethanolamine were reacted in the presence of a solvent, methanol and the like were added, and then recrystallization gave bis (2-aminoethyl) glutamate. Trihydrochloride was obtained. Next, bis (2-aminoethyl) glutamate trihydrochloride was phosgenated in the presence of a solvent, filtered after cooling, and distilled under reduced pressure to obtain GTI (triisocyanate (T-3)). The viscosity of the obtained triisocyanate (T-3) was 50 mPa · s / 25 ° C.

[Example 1] Production of polyisocyanate composition 1, dilute solution 1 of polyisocyanate composition, coating composition 1 and coating film 1 (1) Production of polyisocyanate composition 1 HDI-based isocyanurate type polyisocyanate "Duranate TPA" −100 (trade name) ”(manufactured by Asahi Kasei Corporation, viscosity: 1350 mPa · s / 25 ° C., number average molecular weight: 580) (hereinafter sometimes referred to as“ polyisocyanate (P-1) ”) 0.5 parts by mass of LTI (triisocyanate (T-2)) was mixed with stirring at room temperature over 30 minutes to obtain a polyisocyanate composition 1.

(2) Production of dilute solution 1 of polyisocyanate composition Next, 100.5 parts by mass of the obtained polyisocyanate composition 1 200 parts by mass of butyl acetate containing 500 ppm of water, and dibutyltin dilaurate “Neostan U-100 (Product Name) ”(manufactured by Nitto Kasei Co., Ltd.) 0.3 parts by mass was added and mixed for 5 minutes at room temperature with stirring to obtain a diluted solution 1 of a polyisocyanate composition. About the diluted solution 1 of the obtained polyisocyanate composition, the storage stability was evaluated according to the above-mentioned evaluation method. The evaluation results are shown in Table 1 below.

(3) Manufacture of coating composition 1 Next, the diluted solution 1 of the obtained polyisocyanate composition, and an acrylic polyol ("Setalux 1903 (trade name)", manufactured by Nuplex Resin, resin solid concentration 75%, Hydroxyl value 150 mgKOH / resin g) was blended so that the molar equivalent ratio of isocyanate group to hydroxyl group was 1: 1. Subsequently, the viscosity of the paint was No. The viscosity was adjusted with butyl acetate so as to be 20 seconds at 4 to obtain a coating composition 1.

(4) Manufacture of the coating film 1 Next, the obtained coating composition 1 was applied so as to have a resin film thickness of 30 μm. After leaving at room temperature for 15 minutes, it was cured in an oven at 120 ° C. for 30 minutes to obtain a coating film 1. About the obtained coating film 1, water resistance was evaluated according to the above-mentioned evaluation method. The evaluation results are shown in Table 1 below.

[Examples 2-7, Comparative Examples 1-5] Production of polyisocyanate compositions 2-12, dilute solutions 2-12 of polyisocyanate compositions, coating compositions 2-12 and coatings 2-12 (1) Poly Production of Isocyanate Compositions 2 to 12 The same method as (1) of Example 1 except that the types and blending amounts of polyisocyanate, triisocyanate and other additives were as shown in Table 1 or Table 2 below. Used to produce polyisocyanate compositions 2-12.

(2) Production of dilute solutions 2 to 12 of polyisocyanate composition Next, the same polyisocyanate composition 2 to 12 as in Example 1 (2) except that 100.5 to 110 parts by mass were used. Using the method, dilute solutions 2-12 of the polyisocyanate composition were prepared. About the obtained dilute solutions 2-12 of the polyisocyanate composition, the storage stability was evaluated according to the above-mentioned evaluation method. The evaluation results are shown in Table 1 and Table 2 below.

(3) Manufacture of coating compositions 2 to 12 Next, a coating composition was prepared using the same method as in (3) of Example 1 except that the obtained dilute solutions 2 to 12 of the polyisocyanate composition were used. 2-12 were obtained.

(4) Manufacture of coating films 2 to 12 Next, coating films 2 to 12 were obtained using the same method as (4) of Example 1 except that the obtained coating compositions 2 to 12 were used. . About the obtained coating films 2-12, according to the above-mentioned evaluation method, water resistance was evaluated. The evaluation results are shown in Table 1 and Table 2 below.

From Table 1, dilute solutions 1 to 7 of polyisocyanate compositions produced in Examples 1 to 7 containing polyisocyanate and triisocyanate are large in appearance such as gelation and turbidity after storage at 40 ° C. There was no change.
In addition, the polyisocyanate composition produced in Examples 2, 3, and 5 to 7, wherein the content of LTI (triisocyanate (T-2)) or GTI (triisocyanate (T-3)) is 1 part by mass or more. The diluted solutions 2, 3 and 5 to 7 of the product were particularly good without significant changes in appearance such as gelation and turbidity after storage at 0 ° C.
Moreover, the polyisocyanate composition manufactured in Examples 1, 2, and 4-7 whose content of LTI (triisocyanate (T-2)) or GTI (triisocyanate (T-3)) is less than 3 parts by mass. The diluted solutions 1, 2 and 4 to 7 of the product were particularly good because the difference in APHA values before and after storage at 40 ° C. was less than 15, and no significant change in chromaticity was observed.
Moreover, the coating compositions 1, 2, and 5-7 whose content of LTI (triisocyanate (T-2)) or GTI (triisocyanate (T-3)) is 1 part by mass or less are cured. The coating films 1, 2, and 5-7 produced in Examples 1, 2, and 5-7 did not show a significant change after the water resistance test, and the water resistance was particularly good.

On the other hand, from Table 2, the diisocyanate solution 1 of the polyisocyanate composition produced in Comparative Examples 1, 3, and 5 having a triisocyanate content of 0.005 parts by mass or less or containing methyl orthoformate. In 3 and 5, turbidity was observed after storage at 40 ° C., and the appearance was particularly inferior.
Further, the diisocyanate solutions 1, 3, and 3 of the polyisocyanate composition produced in Comparative Examples 1, 3, and 5 having a triisocyanate content of 0.005 parts by mass or less or containing methyl orthoformate In No. 5, gelation was observed after storage at 0 ° C., and the appearance was particularly inferior.
In addition, diluted solutions 2 and 3 of the polyisocyanate composition produced in Comparative Examples 2 and 3 containing other additives of p-toluenesulfonyl isocyanate or methyl orthoformate have APHA values before and after storage at 40 ° C. The difference was 30 or more, and the change in chromaticity was large and particularly inferior.
Moreover, the coating film 4 manufactured by the comparative example 4 which hardened the coating composition 4 whose content of LTI (triisocyanate (T-2)) is 10 mass parts, Swelling was observed and water resistance was particularly poor.

  From the above, the polyisocyanate composition of the present embodiment contains polyisocyanate and triisocyanate, and the mass ratio of the polyisocyanate to the triisocyanate is 100 / 5.0 or more and 100 / 0.01 or less. It was confirmed that when the polyisocyanate composition was diluted with a solvent, it had excellent storage stability at both high temperature and low temperature. Furthermore, it was confirmed that the coating film obtained from the coating composition containing the polyisocyanate composition of this embodiment has excellent water resistance.

  The polyisocyanate composition of this embodiment has excellent storage stability at both high and low temperatures when diluted with a solvent. Moreover, the coating composition of this embodiment contains the diluted solution of the said polyisocyanate composition as a hardening | curing agent, and can be utilized as coating materials, such as roll coating, curtain flow coating, spray coating, bell coating, and electrostatic coating. . Moreover, the said coating composition can be used as a primer and top intermediate coating material to materials, such as metals, such as a steel plate and a surface-treated steel plate, and a plastic, a timber, a film, and an inorganic material. The coating composition is also useful as a coating that imparts heat resistance, cosmetic properties (surface smoothness, sharpness), etc. to pre-coated metal including a rust-proof steel plate, and painted parts of automobiles. The coating composition is also useful as a raw material for urethane such as adhesives, pressure-sensitive adhesives, elastomers, foams, and surface treatment agents.

Claims (5)

A polyisocyanate obtained from one or more diisocyanates selected from the group consisting of an aliphatic diisocyanate containing 1,6-diisocyanatohexane and an alicyclic diisocyanate containing isophorone diisocyanate;
Including one or more triisocyanates represented by the following general formula (I),
The polyisocyanate composition whose mass ratio of the said polyisocyanate with respect to the said triisocyanate is 100 / 5.0 or more and 100 / 0.01 or less.

... (I)
[In General Formula (I), a plurality of Y ¹ are each independently a single bond, or a divalent group having 1 to 20 carbon atoms that may contain one or more selected from the group consisting of an ester structure and an ether structure. It is a hydrocarbon group. A plurality of Y ¹ may be the same or different. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. ] The polyisocyanate composition according to claim 1, wherein at least ^one of Y ¹ in the triisocyanate contains an ester structure. The polyisocyanate composition according to claim 1 or 2, and a volatile organic solvent,
A dilute solution of a polyisocyanate composition having a mass ratio of the total amount of the polyisocyanate and the triisocyanate to the volatile organic solvent of 5/95 or more and 95/5 or less.   The coating composition containing the diluted solution of the polyisocyanate composition of Claim 3, and a polyol.   A coating film obtained by curing the coating composition according to claim 4.