Polyisocyanate composition and water-based two-component urethane coating composition

Abstract

To provide a polyisocyanate composition that allows high compatibility with a main agent, ensures favorable pot life upon mixing with the main agent, and enables formation of a coating film exhibiting excellent hardness and weather resistance, and also to provide a water-based two-component urethane coating composition.SOLUTION: There is provided a polyisocyanate composition which is a reaction product of an isocyanate compound, a nonionic hydrophilic component, and a long-chain polyol component, wherein an isocyanate group content is 3 mass% or more and 24 mass% or less, and a molar ratio of isocyanurate groups to allophanate groups is from 40:60 to 25:75.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyisocyanate composition and a water-based two-component urethane coating composition. [Background technology]

[0002] Conventionally, a fluorine coating composition containing a fluorine-containing copolymer as a main component and a polyisocyanate component as a curing agent component has been known as a coating composition that can obtain a coating film with excellent weather resistance. This fluorine coating composition is used, for example, as a heavy-duty anticorrosion coating, a structural exterior, an architectural exterior, or a top coat for aircraft, a windmill, a floor, a plastic, an automobile interior member, an optical member, etc. In addition, in recent years, from the viewpoint of protecting the global environment, it is also desired to make a fluorine coating composition that has been used as a solvent-based paint into a water-based paint. In making a water-based paint, a fluorine-containing copolymer obtained by emulsion polymerization is known as a main component, and a polyether-modified isocyanate is used as a curing agent component (for example, see Patent Document 1).

[0003] However, the base resin containing fluorine has low polarity, and the selection of the curing agent may be limited. In order to reduce the polarity, a method of using a polyisocyanate having an allophanate group as a curing agent has been developed (see, for example, Patent Documents 2, 3 and 4). In addition, a method has been developed to improve compatibility with fluorine while maintaining the physical properties of the coating film by modifying the curing agent (see, for example, Patent Document 5). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-324180 [Patent Document 2] International Publication No. 2009 / 130965 [Patent Document 3] International Publication No. 2008 / 142848 [Patent Document 4] JP 2010-116509 A [Patent Document 5] Patent No. 7206089 Summary of the Invention [Problem to be solved by the invention]

[0005] The methods described in Patent Documents 2 to 4 improve the compatibility with the fluorine-containing base agent, but the crosslink density decreases, resulting in poor weather resistance and coating hardness, leaving room for improvement. Furthermore, the method described in Patent Document 5 improves compatibility with the fluorine-containing base resin while maintaining the physical properties of the coating film, but there is room for improvement in the pot life after mixing with the base resin.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyisocyanate composition and an aqueous two-component urethane coating composition that have high compatibility with a base agent, a good pot life when mixed with the base agent, and further have good hardness and weather resistance when formed into a coating film. [Means for solving the problem]

[0007] That is, the present invention includes the following aspects. [1] A polyisocyanate composition which is a reaction product of an isocyanate compound, a nonionic hydrophilic component, and a long-chain polyol component, wherein the isocyanate compound is at least one selected from aliphatic diisocyanates, alicyclic diisocyanates, and isocyanate prepolymers thereof, the nonionic hydrophilic component has one hydroxyl group and is composed of 3 to 20 ethylene oxide repeating units, and the long-chain polyol component is a polyether polyol having 2 to 4 hydroxyl groups and a number average molecular weight of 1,000 to 15,000. a polyisocyanate composition having an isocyanate group content of 3% by mass or more and 24% by mass or less, and a molar ratio of isocyanurate groups to allophanate groups of 40:60 to 25:75. [2] The polyisocyanate composition according to [1], wherein the long-chain polyol component is a polyether polyol. [3] The polyisocyanate composition according to [1] or [2], wherein the isocyanate compound is an isocyanate prepolymer which is a derivative of either one or both of an aliphatic diisocyanate and an alicyclic diisocyanate and an alcohol, the alcohol being at least one selected from a monohydric alcohol having from 1 to 50 carbon atoms and a polyhydric alcohol having from 2 to 50 carbon atoms, and the content of residues of the monohydric alcohol or residues of the polyhydric alcohol relative to the total amount of the polyisocyanate composition is 0.5 mass% or more and 30 mass% or less. [4] The polyisocyanate composition according to any one of [1] to [3], wherein the content of the ionic surfactant relative to the total amount of the polyisocyanate composition is 0.1 mass% or more and 10 mass% or less, and the content of water relative to the total amount of the ionic surfactant is 1 mass% or less. [5] The polyisocyanate composition according to any one of [1] to [3], wherein the isocyanate compound is an isocyanate prepolymer derived from an aliphatic diisocyanate. [6] A water-based two-component urethane coating composition comprising the polyisocyanate composition according to any one of [1] to [5] and an aqueous polyol having a hydroxyl value of 1 mgKOH / g or more and 300 mgKOH / g or less. [7] The aqueous two-component urethane coating composition according to [6], wherein the aqueous polyol contains a fluorine-based polyol or a silicone-based polyol. Effect of the Invention

[0008] According to the present invention, it is possible to provide a polyisocyanate composition and an aqueous two-component urethane coating composition which have high compatibility with a base agent, a good pot life when mixed with the base agent, and further have good hardness and weather resistance when formed into a coating film. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In this specification, the term "polyol" refers to a compound having two or more hydroxyl groups (-OH) in one molecule. In addition, in this specification, the term "polyisocyanate" refers to a reaction product in which a plurality of monomer compounds each having two or more isocyanate groups (-NCO) are bonded together. In this specification, unless otherwise specified, "(meth)acrylic" includes both methacrylic and acrylic, and "(meth)acrylate" includes both methacrylate and acrylate.

[0010] <Polyisocyanate composition> The polyisocyanate composition of the present embodiment is a reaction product of an isocyanate compound, a nonionic hydrophilic component, and a long-chain polyol component.

[0011] <Isocyanate compounds> The isocyanate compound is at least one selected from aliphatic diisocyanates, alicyclic diisocyanates, and isocyanate prepolymers thereof. In the present invention, the aliphatic diisocyanates, alicyclic diisocyanates, and isocyanate prepolymers are collectively referred to as isocyanate compounds.

[0012] Examples of the aliphatic diisocyanate include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (hereinafter, HDI), trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0013] Examples of alicyclic diisocyanates include isophorone diisocyanate (hereinafter, IPDI), xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate (hereinafter, hydrogenated MDI), hydrogenated xylylene diisocyanate (hereinafter, hydrogenated XDI), and 1,4-diisocyanate cyclohexane. HDI, IPDI, hydrogenated MDI, and hydrogenated XDI are relatively inexpensive and industrially easily available, and therefore are preferred. Among these, HDI is the most preferred because the viscosity of the resulting polyisocyanate composition is likely to be low.

[0014] Hereinafter, aliphatic diisocyanates and alicyclic diisocyanates will be collectively referred to as raw material diisocyanates.

[0015] An isocyanate prepolymer is a prepolymer made by a known technique from a raw material diisocyanate, etc. Specifically, the prepolymerization refers to a biuret reaction, an isocyanurate reaction, a urethanization reaction, a urethodione reaction, or an allophanate reaction of a raw material diisocyanate, etc., which can be carried out by a known technique.

[0016] It is safer and more preferable to remove the unreacted raw diisocyanate after the prepolymerization. The raw diisocyanate and the solvent used in the prepolymerization can be removed by, for example, thin film distillation or solvent extraction.

[0017] The isocyanate compound is preferably an isocyanate prepolymer which is a derivative of either or both of an aliphatic diisocyanate and an alicyclic diisocyanate and an alcohol.

[0018] The alcohol is preferably at least one selected from monohydric alcohols having 1 to 50 carbon atoms and polyhydric alcohols having 2 to 50 carbon atoms.

[0019] The monohydric alcohol residue having 1 to 50 carbon atoms refers to a moiety obtained by removing the hydrogen atom of the hydroxyl group contained in the monohydric alcohol from the monohydric alcohol.

[0020] The polyhydric alcohol residue having 2 to 50 carbon atoms is a portion obtained by removing a hydrogen atom of a hydroxyl group of the polyhydric alcohol from the polyhydric alcohol. By containing at least one of a monohydric alcohol residue and a polyhydric alcohol residue, it is possible to impart better water dispersibility to the polyisocyanate composition.

[0021] A monohydric alcohol is an organic compound having one hydroxyl group. The number of carbon atoms in the monohydric alcohol is 1 to 50, preferably 1 to 20, and more preferably 1 to 15. If the number of carbon atoms is within the range of 1 to 50, it is possible to design an appropriate viscosity.

[0022] Examples of monohydric alcohols include saturated aliphatic alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, i-butanol, 1-pentanol, isoamyl alcohol, 1-hexanol, 2-hexanol, 3,3,5-trimethyl-1-hexanol, tridecanol, and pentadecanol, saturated cyclic aliphatic alcohols such as cyclopentanol, cyclohexanol, methylcyclohexanol, and trimethylcyclohexanol, unsaturated aliphatic alcohols such as propenol, butenol, hexenol, and 2-hydroxyethyl acrylate, alcohols containing an ether bond such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether, and alcohols containing an ester bond. One of these may be used, or two or more may be used in combination.

[0023] A polyhydric alcohol is an organic compound having two or more hydroxyl groups. The number of carbon atoms in the polyhydric alcohol is 2 to 50, preferably 2 to 30, and more preferably 2 to 15. If the number of carbon atoms is within the range of 2 to 50, it is possible to design an appropriate viscosity. The number of hydroxyl groups in the polyhydric alcohol is appropriately 2 to 10, preferably 2 to 6, and more preferably 2 to 4. If the number of hydroxyl groups is within the range of 2 to 10, it is possible to impart extensibility while maintaining an appropriate viscosity.

[0024] Examples of polyhydric alcohols are as follows: Examples of dihydric alcohols include hydrocarbon compounds such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,5-pentanediol, 1,6-hexanediol, methylpentanediol, cyclohexanedimethanol, methylpentanediol, and neopentyl glycol; and organic compounds having two hydroxyl groups such as diethylene glycol, triethylene glycol, polyethylene glycol, and polypropylene glycol.

[0025] Examples of trihydric alcohols include organic compounds having three hydroxyl groups, such as glycerin, 2-methyl-2-hydroxymethyl-1,3-propanediol, 2,4-hydroxy-3-hydroxymethylpentane, 1,2,6-hexanetriol, and trimethylolpropane. Examples of the tetrahydric or higher alcohol include sugar alcohols such as tetritols such as erythrose, pentitols such as xylitol, and hexitols such as sorbitol.

[0026] The monohydric alcohols and polyhydric alcohols may be used alone or in combination of two or more kinds.

[0027] The content of the monohydric alcohol residue or polyhydric alcohol residue relative to the total amount of the polyisocyanate composition is preferably 0.5% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 25% by mass or less, and even more preferably 10% by mass or more and 20% by mass or less. When the content is equal to or more than the lower limit, the dispersibility in water is improved. When the content is equal to or less than the upper limit, it is possible to design the appropriate number of functional groups of the isocyanate group and the viscosity.

[0028] <Nonionic hydrophilic component> The nonionic hydrophilic component has one hydroxyl group and is composed of 3 to 20 ethylene oxide repeating units. The nonionic hydrophilic component is a polyalkylene oxide ether alcohol containing an ethylene oxide repeating unit, and the number of hydroxyl groups in this hydrophilic component is at least one. Such compounds include polyethylene glycol, Pluronic (registered trademark) type polyalkylene glycols, etc. A preferred compound is polyethylene glycol monoalkyl ether, and particularly preferred is polyethylene glycol monomethyl ether.

[0029] The number of ethylene oxide repeating units is 3 or more and 20 or less, preferably 4 or more and 20 or less, more preferably 4 or more and 10 or less. If the number of ethylene oxide repeating units is 3 or more, it is possible to obtain sufficient emulsifying ability. If the number of ethylene oxide repeating units is 20 or less, the crystallinity is not too high and the composition is stable. The nonionic hydrophilic component is incorporated into the structure of the polyisocyanate composition to exhibit its ability as a surfactant.

[0030] In the polyisocyanate composition of the present invention, the content of the residue of the nonionic hydrophilic component relative to the total amount of the polyisocyanate composition is 5% by mass or more and 20% by mass or less, preferably 5% by mass or more and 18% by mass or less, and more preferably 5.5% by mass or more and 17% by mass or less. The residue of the nonionic hydrophilic component refers to the portion of the nonionic hydrophilic component obtained by removing the hydrogen atom of the hydroxyl group contained in the nonionic hydrophilic component from the nonionic hydrophilic component.

[0031] <Long-chain polyol component> The long-chain polyol component is at least one selected from polyether polyols and polyester polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 1,000 to 15,000.

[0032] The long-chain polyol component used in the present invention may be one or a mixture of aliphatic hydrocarbon polyols, fluorine-containing polyols, polyether polyols, polyester polyols, polycarbonate polyols, epoxy resins, acrylic polyols, alkyd polyols, etc. Among these, polyether polyols and polyester polyols are preferred because the resulting polyisocyanate composition is more easily dispersed in water, and polyether polyols are particularly preferred because they are more easily dispersed in water.

[0033] Examples of polyether polyols include polyether polyols obtained by adding alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide, either alone or in combination, to a polyhydric hydroxy compound, either alone or in combination, using a strong basic catalyst, such as a hydroxide, alcoholate, or alkylamine, of lithium, sodium, potassium, or the like; polyether polyols obtained by reacting alkylene oxides with polyfunctional compounds, such as ethylenediamines; and so-called polymer polyols obtained by polymerizing acrylamide or the like using these polyethers as a medium.

[0034] Examples of polyhydric hydroxy compounds include glycerin, trimethylolpropane, diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol, and alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol, and rhamnitol; monosaccharides such as arabinose, ribose, xylose, glucolose, mannose, galactose, fructose, sorbose, rhamnose, fucose, and ribodesose; disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and melibiose; trisaccharides such as raffinose, gentianose, and melezitose; and tetrasaccharides such as stachyose.

[0035] Examples of the polyester polyol include polyester polyols obtained by a condensation reaction of a dibasic acid selected from the group consisting of carboxylic acids such as succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid, either alone or in a mixture, with a polyhydric alcohol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, and glycerin, either alone or in a mixture; polycaprolactone polyols obtained by ring-opening polymerization of ε-caprolactone with a polyhydric alcohol; and polycarbonate polyols.

[0036] The long-chain polyol component has a number average molecular weight of 1000 to 15000, preferably 2000 to 12000, and more preferably 3000 to 10000. If the number average molecular weight is 1000 or more, it is possible to impart extensibility. If the number average molecular weight is 15000 or less, it is possible to design an appropriate viscosity.

[0037] The number of hydroxyl groups in the long-chain polyol is from 2 to 4, and preferably from 2 to 3. If the number of hydroxyl groups is 2 or more, extensibility can be imparted, and if the number is 4 or less, an appropriate viscosity can be designed.

[0038] A long chain polyol component can be incorporated into the structure of the polyisocyanate composition to impart extensibility to the water-based coating composition. The polyisocyanate composition of the present invention has a content of residues of a long-chain polyol component of 6% by mass or more and 30% by mass or less of the total amount of the polyisocyanate composition. The residues of a long-chain polyol component refer to the portion of the long-chain polyol component obtained by removing hydrogen atoms of hydroxyl groups contained in the long-chain polyol component.

[0039] The polyisocyanate composition has an isocyanate group content of 3% by mass or more and 24% by mass or less, preferably 4% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 16% by mass or less. If the isocyanate group content is within the above range, the compatibility with the base agent is high, and furthermore, the hardness and weather resistance of the formed coating film are likely to be improved.

[0040] The polyisocyanate composition has a molar ratio of isocyanurate groups to allophanate groups of 40:60 to 25:75. When the molar ratio of isocyanurate groups to allophanate groups is within the above range, the compatibility with the fluorine-based base resin is high, the pot life when mixed with the base resin is good, and further the hardness and weather resistance when formed into a coating film are improved.

[0041] The viscosity of the polyisocyanate composition of the present invention is, for example, 100 mP·s or more and 100,000 mP·s or less, preferably 100 mP·s or more and 50,000 mP·s or less, and more preferably 500 mP·s or more and 1,000 mP·s or less. If the viscosity is within the above range, the composition can be easily dispersed in water.

[0042] <Ionic surfactants> The polyisocyanate composition preferably further contains an ionic surfactant. In this case, the content of the ionic surfactant relative to the total amount of the polyisocyanate composition is preferably 0.1% by mass or more and 10% by mass or less.

[0043] The ionic surfactant preferably does not substantially contain water. The term "substantially does not contain water" means that the water contained in the ionic surfactant does not react with the isocyanate group to cause foaming, clouding, or an increase in viscosity. Specifically, the content of water in the ionic surfactant is preferably 1% by mass or less based on the total amount of the ionic surfactant.

[0044] The addition of an ionic surfactant improves emulsifiability and enhances the ability to protect isocyanate groups from water, improving the retention of isocyanate groups in the aqueous dispersion and the pot life of the coating composition.

[0045] The ionic surfactant used in the present invention can be selected as an anionic surfactant or a cationic surfactant according to the neutralization method of the aqueous polyol of the main component used in the present invention.Specifically, when the aqueous polyol is neutralized by base, an anionic surfactant is preferred, and when the aqueous polyol is neutralized by acid, it is preferred to use a cationic surfactant, since it does not cause aggregation.When the aqueous polyol is not neutralized, either an anionic surfactant or a cationic surfactant can be used.

[0046] Examples of anionic surfactants include ammonium alkylbenzenesulfonate, sodium alkyldisulfate, sodium alkyldiphenyletherdisulfonate, and sodium dialkylsulfosuccinate. Examples of cationic surfactants include quaternary ammonium salts, pyridinium salts, and imidazolinium salts. Examples of such surfactants include alkyltrimethylammonium bromide, alkylpyridinium bromide, and imidazolinium laurate.

[0047] The content of the ionic surfactant that can be used in the present invention is preferably 0.1% by mass or more and 10% by mass or less, more preferably 1.5% by mass or more and 8% by mass or less, and even more preferably 1.5% by mass or more and 7% by mass or less, based on the total amount of the polyisocyanate composition. When the content of the ionic surfactant is equal to or more than the lower limit, the effect of dispersion stability due to the mixing of the ionic surfactant can be expected. When the content is equal to or less than the upper limit, it is possible to form a tough film without too many components that are not involved in crosslinking.

[0048] <<Method for producing polyisocyanate composition>> The polyisocyanate composition of the present invention is a reaction product obtained by reacting an isocyanate compound, a nonionic hydrophilic component, and a long-chain polyol component. The polyisocyanate composition of the present invention may be one obtained by subjecting a monohydric alcohol or a polyhydric alcohol to a urethanization reaction, if necessary, and an allophanation reaction, if necessary. The polyisocyanate composition of the present invention may further contain an ionic surfactant, if necessary.

[0049] The urethanization reaction is a reaction that produces a urethane group from an isocyanate group and a hydroxyl group. For example, an isocyanate compound and a compound having a hydroxyl group can be simply mixed and reacted, or a known urethanization catalyst such as dibutyltin laurate can be added as necessary. The reaction temperature is 20 to 200°C, preferably 40 to 180°C, and more preferably 60 to 160°C.

[0050] The allophanate reaction is a reaction that generates an allophanate group from an isocyanate group and a urethane group. The allophanate reaction can be carried out by a known technique. For example, a method can be adopted in which an isocyanate compound and a compound having a urethane group are mixed and reacted at a temperature of 150°C or higher, preferably 160°C or higher. Alternatively, a method can be adopted in which an isocyanate compound and a compound having a urethane group are mixed and reacted using a known allophanate catalyst. The reaction using an allophanate catalyst is carried out at a temperature of, for example, 20°C or higher and 200°C or lower, preferably 40°C or higher and 180°C or lower, more preferably 60°C or higher and 160°C or lower.

[0051] The urethanization reaction and the allophanate reaction may be carried out simultaneously, or the allophanate reaction may be started during the urethanization, or the allophanate reaction may be carried out after the urethanization reaction.

[0052] The urethane reaction of an isocyanate compound, a nonionic hydrophilic component, a long-chain polyol component, and, if necessary, a monohydric alcohol or a polyhydric alcohol, and further, if necessary, an allophanate reaction, may be carried out by any method, but examples of the method include the following method.

[0053] (Manufacturing method example 1) Production method example 1 is a method in which a raw material diisocyanate is prepolymerized, and then a nonionic hydrophilic component, a long-chain polyol component, and at least one selected from a monohydric alcohol and a polyhydric alcohol are urethane-converted and, if necessary, allophanated.

[0054] (Manufacturing method example 2) Production method example 2 is a method in which an isocyanate prepolymer is produced from a nonionic hydrophilic component, and optionally at least one selected from a monohydric alcohol and a polyhydric alcohol, and a raw material diisocyanate, and then a long-chain polyol component and optionally at least one selected from a monohydric alcohol and a polyhydric alcohol are urethane-converted, and optionally further allophanated.

[0055] (Manufacturing method example 3) Production method example 3 is a method in which an isocyanate prepolymer is produced from a long-chain polyol component and, if necessary, at least one selected from a monohydric alcohol and a polyhydric alcohol, and a raw material diisocyanate, and a nonionic hydrophilic component and, if necessary, at least one selected from a monohydric alcohol and a polyhydric alcohol are urethane-converted, and if necessary, further allophanated.

[0056] (Manufacturing method example 4) Production method example 4 is a method in which an isocyanate prepolymer is produced from at least one selected from a monohydric alcohol and a polyhydric alcohol and a raw material diisocyanate, and a nonionic hydrophilic component and a long-chain polyol component are urethane-converted and, if necessary, further allophanated.

[0057] (Manufacturing method example 5) Production method example 5 is a method in which a prepolymer is produced from a nonionic hydrophilic component, a long-chain polyol component, and a raw material diisocyanate, and at least one selected from a monohydric alcohol and a polyhydric alcohol is optionally urethane-converted, and optionally further allophanated.

[0058] (Manufacturing method example 6) Production method example 6 is a method in which a raw material diisocyanate is urethane-treated with a nonionic hydrophilic component, a long-chain polyol component, and, if necessary, at least one selected from a monohydric alcohol and a polyhydric alcohol, and further allophanated if necessary.

[0059] Production methods 1, 2, 3, 4 and 5 are preferred in that they are easy to produce and to manage production. Production method 6 is preferred in that the viscosity of the resulting polyisocyanate composition is low. In addition, the polyisocyanate composition obtained by adding an isocyanate compound, a nonionic hydrophilic component, a long-chain polyol component, and, if necessary, at least one of a monohydric alcohol and a polyhydric alcohol to the polyisocyanate composition and subjecting the mixture to urethanization and / or allophanation may, if necessary, be further subjected to prepolymerization by a known technique.

[0060] In addition, these reactions may or may not involve the use of a solvent, but when a solvent is used, it is preferable to select a solvent that has no reactivity with the isocyanate group. Examples of the solvent include aliphatic hydrocarbon organic solvents such as mineral spirits, aromatic hydrocarbon organic solvents such as diethylbenzene, trimethylbenzene, and xylene, ether organic solvents such as dibutyl ether, ester organic solvents such as butyl acetate, ketone organic solvents such as methyl ethyl ketone, and mixtures thereof. Among these, hydrophilic ether organic solvents and ester organic solvents not having active hydrogen, such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethyl glycol diacetate, are particularly preferred.

[0061] After the reaction is completed, if necessary, the unreacted raw diisocyanate and the solvent may be removed. If any unreacted raw diisocyanate remains, it is preferable to remove it for safety reasons. In addition, the ionic surfactant may be mixed before, simultaneously with, or after the urethane reaction of the isocyanate compound, the nonionic hydrophilic component, the long-chain polyol component, and, if necessary, the monohydric alcohol or the polyhydric alcohol, and the allophanate reaction.

[0062] In the polyisocyanate composition of the present invention, a urethanization catalyst can be added as necessary. Known compounds can be used as the urethanization catalyst. For example, tin compounds such as dibutyltin dilaurate, zirconium compounds such as zirconyl 2-ethylhexanoate and zirconium acetylacetonate, and zinc compounds such as zinc 2-ethylhexanoate can be used. Dibutyltin laurate is particularly preferred because it has a high curing acceleration effect.

[0063] <Water-based two-liquid urethane coating composition> The present invention relates to an aqueous two-component urethane coating composition comprising the polyisocyanate composition of the present embodiment and an aqueous polyol having a hydroxyl value of 1 mgKOH / g or more and 300 mgKOH / g or less.

[0064] The aqueous polyol used in the present invention includes all water-dispersible polyols such as latex and emulsion, as well as water-soluble polyols.

[0065] The water-dispersible polyol is preferably a fluorine-based polyol or a silicone-based polyol.

[0066] Examples of the latex and emulsion include polyvinylidene chloride copolymer latex, polyvinyl chloride copolymer latex, vinyl acetate copolymer latex, urethane emulsion, acrylic latex, fluorine-containing copolymer emulsion, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, polybutadiene copolymer latex, urethane acrylic emulsion, polyester latex, and the like.

[0067] Examples of water-soluble polyols include acrylic acid ester resins, polyester resins, polyurethane resins, vinyl acetate resins, polyvinyl alcohol resins, epoxy resins, and polyalkylene oxide polyol resins. These can be obtained by known techniques. Latex and emulsion are preferred because they have better water resistance than water-soluble polyols. In particular, urethane emulsions, acrylic latexes, and fluorine-containing copolymer emulsions are more preferred because they have better weather resistance.

[0068] The hydroxyl value of the aqueous polyol used in the present invention is, for example, 1 mgKOH / g or more and 300 mgKOH / g or less, preferably 5 mgKOH / g or more and 150 mgKOH / g or less, and more preferably 10 mgKOH / g or more and 100 mgKOH / g or less. If the hydroxyl value of the aqueous polyol is 1 mgKOH / g or more and 300 mgKOH / g or less, appropriate crosslinking occurs in the coating composition, and a tough coating film can be formed. Note that the hydroxyl value referred to in the present invention is a value relative to the non-volatile content of the aqueous polyol.

[0069] The particle size of the latex or emulsion used in the present invention is, for example, 0.01 μm or more and 1.0 μm or less, preferably 0.02 μm or more and 0.5 μm or less, and more preferably 0.05 μm or more and 0.2 μm or less. If the particle size of the latex or emulsion is 0.01 μm or more, the viscosity is appropriate. If the particle size of the latex or emulsion is 1.0 μm or less, the latex or emulsion is stable.

[0070] In the present invention, the equivalent ratio of the isocyanate group / hydroxyl group of the aqueous polyol and the polyisocyanate composition is, for example, 0.5 to 5.0, preferably 0.8 to 3.0, and more preferably 1.0 to 2.0. If it is 0.5 to 5.0, appropriate crosslinking occurs in the coating composition, and a tough coating film can be formed.

[0071] The polyisocyanate composition of the present invention can be used by adding an organic solvent. The polyisocyanate composition to which an organic solvent has been added has a lower viscosity, which makes it easier to handle and easier to disperse in water. In this case, it is necessary that the organic solvent does not have a functional group that reacts with an isocyanate group. In addition, it is necessary that the organic solvent is compatible with the polyisocyanate composition of the present invention.

[0072] Examples of such organic solvents include ester compounds such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, isopentyl acetate, methoxypropyl acetate, 3-methoxybutyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, cyclohexyl acetate, methyl propionate, butyl propionate, butyl butyrate, dioctyl adipate, and diisopropyl glutarate; and ether compounds such as diisopropyl ether, dibutyl ether, dibutyl ether, dioxane, and diethoxyethane.

[0073] Examples of the organic solvent include ketone compounds such as 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone, isophorone, cyclohexanone, and methylcyclohexanone.

[0074] Examples of the organic solvent include aromatic compounds such as benzene, toluene, xylene, ethylbenzene, butylbenzene, and p-cymene.

[0075] Examples of the organic solvent include polyethylene glycol diethyl alkyl ether compounds such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and triethylene glycol dimethyl ether.

[0076] Examples of the organic solvent include polyethylene glycol dicarboxylate compounds such as diethylene glycol diacetate, diethylene glycol monoalkyl ether monocarboxylates such as diethylene glycol monoethyl ether monoacetate and diethylene glycol monobutyl ether acetate, and n-methylpyrrolidone.

[0077] A urethanization reaction catalyst can be added to the aqueous polyol used in the present invention as necessary. Known compounds can be used as the urethanization catalyst. For example, tin compounds such as dibutyltin laurate, zirconium compounds such as zirconyl 2-ethylhexanoate and zirconium acetylacetonate, and zinc compounds such as zinc 2-ethylhexanoate can be used. In particular, catalysts in the form of aqueous dispersions are preferred because they are easily dispersed in aqueous polyols. Such compounds that have been commercialized include SCAT-1W (a water dispersion of dibutyltin dilaurate, manufactured by Sankyo Kigosei Co., Ltd.).

[0078] The polyisocyanate composition and the aqueous two-liquid urethane coating composition of the present invention may contain pigments, dispersion stabilizers, viscosity modifiers, leveling agents, light stabilizers, antioxidants, UV absorbers, fillers, plasticizers, lubricants, curing accelerator catalysts, defoamers, etc., as necessary. In particular, the use of UV absorbers is preferable because it improves weather resistance. The polyisocyanate composition and the aqueous coating composition of the present invention have both high emulsifying power and extensibility, and therefore can be used in applications that were difficult with conventional aqueous polyisocyanate compositions, that is, applications that require following cracks and cracks in concrete substrates and other substrate deformations. They are particularly suitable for architectural exterior paints, architectural interior paints, automotive repair paints, and plastic paints. They can also be used in a wide range of fields, such as other paints, sealants, adhesives, inks, coating agents, casting agents, elastomers, foams, plastic raw materials, and fiber treatment agents. EXAMPLES

[0079] Hereinafter, the present embodiment will be described in more detail based on examples and comparative examples, but the present embodiment is not limited to the following examples in any way.

[0080] [Materials used] Methoxypolyethylene glycol was used as the nonionic hydrophilic component. Methoxypolyethylene glycol has one hydroxyl group and nine ethylene oxide repeating units. Hereinafter, methoxypolyethylene glycol will be referred to as "N1". A trifunctional polyether polyol (polypropylene type, terminal ethylene oxide added) was used as the long-chain polyol component. The trifunctional polyether polyol has three hydroxyl groups and a number average molecular weight of 6400. Hereinafter, the trifunctional polyether polyol will be referred to as "P1". As the ionic surfactant, sodium dialkyl succinate sulfonate was used. Hereinafter, sodium dialkyl succinate sulfonate will be referred to as "I1". As the fluorine polyol, Lumiflon FE4400 (product name, fluorine emulsion, manufactured by AGC Corporation) was used.

[0081] [Synthesis Example 1] The inside of a four-neck flask equipped with a stirrer, a thermometer, and a cooling tube was replaced with nitrogen, and 100 g of HDI and 10 g of 2-ethylhexanol were charged and subjected to a urethane reaction at 80°C for 1 hour under stirring. 0.1 g of tetramethylammonium caprylate was added as an isocyanurate and allophanate catalyst, and the reaction was carried out for about 3 hours. The reaction was stopped by adding 0.02 g of an aqueous solution of phosphoric acid with a solid content of 85%. Unreacted HDI was removed using a falling thin film distillation apparatus at 160°C (0.3 Tor) for the first time and 150°C (0.1 Tor) for the second time. The obtained isocyanate prepolymer was a transparent liquid, with a yield of 49.5 g, a viscosity of 420 mPa·s, an isocyanate group content of 17.8%, and a monohydric alcohol content of 18% by mass. The isocyanurate polymer obtained in Synthesis Example 1 is designated as Isocyanurate Polymer A1.

[0082] [Example 1] In the same apparatus as in Synthesis Example 1, 75 g of isocyanurate polymer A1, 15 g of N1, 10 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 11.1% and a viscosity of 1070 mPa s. The polyisocyanate composition obtained in Example 1 is referred to as polyisocyanate composition 1.

[0083] [Synthesis Example 2] In the same apparatus as in Synthesis Example 1, 67 g of isocyanurate polymer A1, 27 g of N1, and 6 g of I1 were mixed and subjected to a urethane reaction at 120°C for 3 hours. The obtained polyisocyanate composition was a pale yellow liquid with an isocyanate group content of 9.02% and a viscosity of 1052 mPa s. The polyisocyanate composition obtained in Synthesis Example 2 is referred to as polyisocyanate composition A2.

[0084] [Synthesis Example 3] In the same apparatus as in Synthesis Example 1, 71.4 g of isocyanurate polymer A1 and 28.6 g of P1 were mixed and subjected to a urethane reaction at 80°C for 1 hour. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 12.3% and a viscosity of 1540 mPa s. The polyisocyanate composition obtained in Synthesis Example 3 is referred to as polyisocyanate composition A3.

[0085] [Example 2] Polyisocyanate composition A2 and polyisocyanate composition A3 were mixed in a ratio of polyisocyanate composition A2 / polyisocyanate composition A3 = 33 / 66 to obtain polyisocyanate composition 2. The obtained polyisocyanate composition 2 was a transparent liquid with an isocyanate group content of 11.0% and a viscosity of 1600 mPa s.

[0086] [Synthesis Example 4] The inside of a four-neck flask equipped with a stirrer, thermometer, and cooling tube was replaced with nitrogen, and 100g of HDI and 7.75g of 2-ethylhexanol were charged and subjected to a urethane reaction at 90°C for 1 hour under stirring. After heating to 130°C, 0.03g of 2-ethylhexanoic acid ZrO was added as an allophanate catalyst and reacted for about 2 hours, and 0.28g of a 2-ethyl-1-hexanol solution of pyrophosphoric acid (solid content 10%) (manufactured by Taihei Chemical Industry, product name "Phosphoric acid (105%)" diluted with 2-ethyl-1-hexanol) was added and post-treated at 130°C for 1 hour to stop the reaction. Unreacted HDI was removed using a falling thin-film distillation apparatus at 160°C (0.3 Tor) for the first time and 150°C (0.1 Tor) for the second time. The obtained isocyanate prepolymer was a transparent liquid, with a yield of 29 g, a viscosity of 110 mPa s, an isocyanate group content of 17.2%, and a monohydric alcohol content of 18 mass%. The isocyanurate polymer obtained in Synthesis Example 4 is designated as Isocyanurate Polymer A4.

[0087] [Example 3] In the same apparatus as in Synthesis Example 1, 74 g of isocyanurate polymer A1, 16.2 g of N1, 9.9 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 10.7% and a viscosity of 1150 mPa s. The polyisocyanate composition obtained in Example 3 is referred to as polyisocyanate composition 3.

[0088] [Example 4] In the same apparatus as in Synthesis Example 1, 74 g of isocyanurate polymer A1, 16.4 g of N1, 9.8 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 11.1% and a viscosity of 1160 mPa s. The polyisocyanate composition obtained in Example 4 is referred to as polyisocyanate composition 4.

[0089] [Example 5] In the same apparatus as in Synthesis Example 1, 85 g of isocyanurate polymer A1, 5 g of N1, 10 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 16.5% and a viscosity of 1020 mPa s. The polyisocyanate composition obtained in Example 5 is referred to as polyisocyanate composition 5.

[0090] [Example 6] In the same apparatus as in Synthesis Example 1, 70 g of isocyanurate polymer A1, 20 g of N1, 10 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 9.7% and a viscosity of 2000 mPa s. The polyisocyanate composition obtained in Example 6 is referred to as polyisocyanate composition 6.

[0091] [Example 7] In the same apparatus as in Synthesis Example 1, 79 g of isocyanurate polymer A1, 15 g of N1, 6 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 13.1% and a viscosity of 700 mPa s. The polyisocyanate composition obtained in Example 7 is referred to as polyisocyanate composition 7.

[0092] [Example 8] In the same apparatus as in Synthesis Example 1, 83.75 g of isocyanurate polymer A1, 9.75 g of N1, 6.5 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 9.7% and a viscosity of 2520 mPa s. The polyisocyanate composition obtained in Example 8 is referred to as polyisocyanate composition 8.

[0093] [Synthesis Example 5] The inside of a four-neck flask equipped with a stirrer, thermometer, and condenser was replaced with nitrogen, and 100 g of HDI and 0.11 g of tetramethylammonium caprylate as an isocyanurate catalyst were added and reacted for about 4 hours. 0.01 g of an aqueous solution of phosphoric acid with a solid content of 85% was added and post-treated at 100°C for 1 hour to stop the reaction. Unreacted HDI was removed using a falling thin-film distillation apparatus at 160°C (0.3 Tor) for the first time and 150°C (0.1 Tor) for the second time. The obtained isocyanate prepolymer was a transparent liquid with a yield of 24.0 g, a viscosity of 1500 mPa·s, and an isocyanate group content of 23.25%. This isocyanurate polymer was designated isocyanurate polymer A5.

[0094] [Example 9] In the same apparatus as in Synthesis Example 1, 70 g of isocyanurate polymer A1, 5 g of isocyanurate polymer A5, 15 g of N1, 10 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 11.5% and a viscosity of 1050 mPa s. The polyisocyanate composition obtained in Example 9 is referred to as polyisocyanate composition 9.

[0095] [Example 10] Polyisocyanate composition 1 obtained in Example 1 and isocyanurate polymer A4 obtained in Synthesis Example 4 were mixed in a weight ratio of 80 / 20 (polyisocyanate composition 1 / isocyanurate polymer A4) to obtain a polyisocyanate composition. The obtained polyisocyanate composition was a transparent liquid, with an isocyanate group content of 12.5% ​​and a viscosity of 700 mPa s. The polyisocyanate composition obtained in Example 10 is designated as polyisocyanate composition 10.

[0096] [Example 11] In the same apparatus as in Synthesis Example 1, 75 g of isocyanurate polymer A1, 15 g of N1, and 10 g of P1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 11.1% and a viscosity of 1000 mPa s. The polyisocyanate composition obtained in Example 11 is designated as polyisocyanate composition 11.

[0097] [Comparative Example 1] In the same apparatus as in Synthesis Example 1, 88 g of isocyanurate polymer A1, 2 g of N1, 10 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 16.0% and a viscosity of 980 mPa s. The polyisocyanate composition obtained in Comparative Example 1 is designated as polyisocyanate composition 1B.

[0098] [Comparative Example 2] In the same apparatus as in Synthesis Example 1, 79 g of isocyanurate polymer A1, 21 g of N1, 10 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 8.7% and a viscosity of 2020 mPa s. The polyisocyanate composition obtained in Comparative Example 2 is designated as polyisocyanate composition 2B.

[0099] [Comparative Example 3] In the same apparatus as in Synthesis Example 1, 79 g of isocyanurate polymer A1, 15 g of N1, 4 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 13.5% and a viscosity of 650 mPa s. The polyisocyanate composition obtained in Comparative Example 3 is designated as polyisocyanate composition 3B.

[0100] [Comparative Example 4] In the same apparatus as in Synthesis Example 1, 57 g of isocyanurate polymer A1, 12 g of N1, 31 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 7.72% and a viscosity of 3307 mPa s. The polyisocyanate composition obtained in Comparative Example 4 is designated as polyisocyanate composition 4B.

[0101] [Comparative Example 5] In the same apparatus as in Synthesis Example 1, 65 g of isocyanurate polymer A1, 10 g of isocyanurate polymer A5, 15 g of N1, 10 g of P1, and 2 g of I1 were mixed and subjected to a urethane reaction at 120°C for 4 hours. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 11.4% and a viscosity of 1040 mPa s. The polyisocyanate composition obtained in Comparative Example 5 is designated as polyisocyanate composition 5B.

[0102] [Comparative Example 6] Isocyanurate polymer A1 and isocyanurate polymer A4 were mixed in a weight ratio of 70 / 30 (isocyanurate polymer A1 / isocyanurate polymer A4) to obtain a polyisocyanate composition. The obtained polyisocyanate composition was a transparent liquid with an isocyanate group content of 13.4% and a viscosity of 670 mPa s. The polyisocyanate composition obtained in Comparative Example 6 is referred to as polyisocyanate composition 6B.

[0103] [Measurement of isocyanate group (NCO) content] The isocyanate group (NCO) content (mass %) was determined by neutralizing the isocyanate groups in each polyisocyanate composition with an excess of 2N amine, and then performing back titration with 1N hydrochloric acid.

[0104] [Viscosity measurement] The viscosity of each polyisocyanate composition was measured at 25° C. using an E-type viscometer (manufactured by Tokimec Co., Ltd.). A standard rotor (1°34′×R24) was used for the measurement. The rotation speeds were as follows.

[0105] (Rotation Speed) 100 rpm (less than 128 mPa s) 50 rpm (for 128 mPa s or more and less than 256 mPa s) 20 rpm (for values ​​between 256 mPa s and 640 mPa s) 10 rpm (for values ​​between 640 mPa s and 1280 mPa s) 5 rpm (for 1280 mPa s or more but less than 2560 mPa s)

[0106] [Evaluation of compatibility with base agent] The polyisocyanate composition and fluorine emulsion (product name Lumiflon manufactured by AGC) were mixed in a ratio where the equivalent ratio of isocyanate group / hydroxyl group was 1.25, and water was added in a ratio where the solid content mass of the polyisocyanate composition and polyol was 47% to obtain a water-based two-component urethane coating composition. The obtained water-based two-component urethane coating composition was applied to a glass plate to prepare a coating film, which was then dried. The surface appearance was observed to confirm the compatibility of the polyisocyanate composition obtained in the examples and comparative examples, which is a curing agent, with the acrylic polyol, which is a base agent. The compatibility with the base agent was evaluated according to the following evaluation criteria. The results are shown in Tables 1 to 2.

[0107] (Evaluation Criteria) ◎: The entire coating is transparent and not cloudy. ○: 10-30% of the coating area is cloudy in appearance △: 30-50% of the coating area is cloudy in appearance ×: The entire coating film appears cloudy and separated.

[0108] [Pot life evaluation] A polyisocyanate composition and a fluorine emulsion (trade name Lumiflon, manufactured by AGC) were mixed in a ratio where the equivalent ratio of isocyanate group / hydroxyl group was 1.25, and water was added in a ratio where the solid content mass of the polyisocyanate composition and polyol was 47%, to obtain a water-based two-component urethane coating composition. The obtained water-based two-component urethane coating composition was stored at 23°C for 1 day, and then the increase rate of the viscosity at 25°C when the initial viscosity was taken as 100% was evaluated. The results are shown in Tables 1-2.

[0109] (Evaluation Criteria) ◎: Viscosity increase rate is 100% or more but less than 150% ○: Viscosity increase rate is 150% or more but less than 180% △: Viscosity increase rate is 180% or more but less than 200% ×: Viscosity increase rate is 200% or more

[0110] [Coating film preparation method] A polyisocyanate composition and a water-based fluorine polyol (product name Lumiflon, manufactured by AGC) were mixed in a ratio where the equivalent ratio of isocyanate group / hydroxyl group was 1.25, and water was added in a ratio where the solid content mass of the polyisocyanate composition and polyol was 47%, to obtain a water-based two-component urethane coating composition. The obtained water-based two-component urethane coating composition was applied to a white enamel painted board with an applicator so that the film thickness after drying was 40 μm, and the coating was aged for one week under conditions of 20°C and 63% humidity.

[0111] [Weather resistance evaluation of polyisocyanate compositions] The weather resistance of the coating film obtained by the method described in [Coating film preparation method] above was evaluated. The weather resistance was evaluated using a Dew Panel Weather Meter (manufactured by Suga Test Instruments Co., Ltd.). The evaluation conditions were in accordance with JIS D0205, with an irradiation illuminance of 30 W / m 2 The panel temperature was 60°C, and the irradiation and dew condensation times were 4 hours each. Gloss retention of 80% or more after 5000 hours of exposure was evaluated as ○, and that of less than 80% was evaluated as ×. The results are shown in Tables 1 and 2.

[0112] (Evaluation Criteria) ◎: Gloss retention is 85% or more Good: Gloss retention is 80% or more but less than 85% △: Gloss retention is 70% or more but less than 80% ×: Gloss retention is less than 70%

[0113] [Table 1]

[0114] [Table 2]

[0115] According to the present invention, it has been confirmed that it is possible to provide a polyisocyanate composition and an aqueous two-component urethane coating composition which have high compatibility with a base agent, a good pot life when mixed with the base agent, and further have good hardness and weather resistance when formed into a coating film.

Claims

1. A polyisocyanate composition which is a reaction product of an isocyanate compound, a nonionic hydrophilic component, and a long-chain polyol component, The isocyanate compound is at least one selected from the group consisting of an aliphatic diisocyanate, an alicyclic diisocyanate, and an isocyanate prepolymer thereof; The nonionic hydrophilic component has one hydroxyl group and is composed of 3 to 20 ethylene oxide repeating units, the long-chain polyol component is at least one selected from the group consisting of polyether polyols and polyester polyols having 2 to 4 hydroxyl groups and a number average molecular weight of 1,000 to 15,000, The content of the residue of the nonionic hydrophilic component relative to the total amount of the polyisocyanate composition is 5% by mass or more and 20% by mass or less, the content of the residue of the long-chain polyol component relative to the total amount of the polyisocyanate composition is 6% by mass or more and 30% by mass or less; The polyisocyanate composition has an isocyanate group content of 3% by mass or more and 24% by mass or less, and a molar ratio of isocyanurate groups to allophanate groups of 40:60 to 25:

75.

2. The polyisocyanate composition of claim 1 , wherein the long-chain polyol component is a polyether polyol.

3. the isocyanate compound is an isocyanate prepolymer which is a derivative of either one or both of an aliphatic diisocyanate and an alicyclic diisocyanate and an alcohol; The alcohol is at least one selected from a monohydric alcohol having from 1 to 50 carbon atoms and a polyhydric alcohol having from 2 to 50 carbon atoms, 3. The polyisocyanate composition according to claim 1, wherein the content of the residue of the monohydric alcohol or the residue of the polyhydric alcohol relative to the total amount of the polyisocyanate composition is 0.5% by mass or more and 30% by mass or less.

4. The content of the ionic surfactant relative to the total amount of the polyisocyanate composition is 0.1% by mass or more and 10% by mass or less, The polyisocyanate composition according to claim 1 or 2, wherein the ionic surfactant has a water content of 1 mass% or less based on the total amount of the ionic surfactant.

5. The polyisocyanate composition according to claim 1 or 2, wherein the isocyanate compound is an isocyanate prepolymer derived from an aliphatic diisocyanate.

6. The polyisocyanate composition according to claim 1 or 2, and an aqueous polyol having a hydroxyl value of 1 mgKOH / g or more and 300 mgKOH / g or less.

7. The water-based two-component urethane coating composition according to claim 6, wherein the water-based polyol contains a fluorine-based polyol or a silicone-based polyol.

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