Polyisocyanate composition and aqueous two-component urethane coating composition

Abstract

The invention relates to a polyisocyanate composition and an aqueous two-component urethane coating composition. [Problem] To provide a polyisocyanate composition and an aqueous two-component urethane coating composition which have high compatibility with a main agent, good pot life when mixed with the main agent, and good hardness and weather resistance when formed into a coating film. [Solution] A polyisocyanate composition which is a reaction product of an isocyanate compound, a nonionic hydrophilic component, and a long-chain polyol component, the content of isocyanate groups being 3-24 mass%, and the molar ratio of isocyanurate groups to allophanate groups being 40: 60-25: 75.

Description

Technical Field

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

[0002] As a coating composition capable of obtaining a coating film with excellent weather resistance, a fluorine coating composition containing a fluorine-containing copolymer as a main component and a polyisocyanate component as a curing agent component is known. The fluorine coating composition is used as a top coating of, for example, heavy anti-corrosion coatings, structural outer packaging, building outer packaging, aircraft, windmills, floors, plastics, automotive interior components, and optical components. In addition, in recent years, from the perspective of global environmental protection, it is also desired to water-system the fluorine coating composition that was previously used in the form of a solvent-based coating. Regarding water-systemization, as a main component, a fluorine-containing copolymer obtained by emulsion polymerization is known, and as a curing agent component, a polyether-modified isocyanate is used (for example, with reference to Patent Document 1).

[0003] However, the polarity of the main agent containing fluorine is low, and the choice of curing agent is sometimes limited. In order to reduce the polarity, a method of using a polyisocyanate having an allophanate group as a curing agent has been developed so far (for example, refer to Patent Documents 2, 3 and 4).

[0004] In addition, a method has been developed in which the compatibility with fluorine is improved while maintaining the physical properties of the coating film by modifying the curing agent (for example, see Patent Document 5).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 7-324180

[0008] Patent Document 2: International Publication No. 2009 / 130965

[0009] Patent Document 3: International Publication No. 2008 / 142848

[0010] Patent Document 4: Japanese Patent Application Publication No. 2010-116509

[0011] Patent Document 5: Japanese Patent No. 7206089 Summary of the invention

[0012] Problem that the invention aims to solve

[0013] In the methods described in Patent Documents 2 to 4, although the compatibility with the main agent containing fluorine is improved, the crosslinking density is reduced, and the weather resistance and the hardness of the coating film are deteriorated, so there is room for improvement.

[0014] In addition, the method described in Patent Document 5 improves compatibility with a fluorine-containing main agent while maintaining the physical properties of the coating film, but there is still room for improvement in the usable time (pot life) after mixing with the main agent.

[0015] The present invention is made in view of the above situation, and its purpose is to provide a polyisocyanate composition and a water-based two-component urethane coating composition which have high compatibility with a main agent, a good pot life when mixed with the main agent, and good hardness and weather resistance when formed into a coating film.

[0016] Solutions for solving problems

[0017] That is, the present invention includes the following aspects.

[0018] [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 contains 3 or more and 20 or less ethylene oxide repeating units, and the long-chain polyol component is selected from polyisocyanates having 2 or more and 4 or less hydroxyl groups and having a number average molecular weight of 1,000 or more and 15,000 or more. At least one of the following polyether polyols and polyester polyols, the content of the residue of the aforementioned nonionic hydrophilic component is 5% by mass or more and 20% by mass or less relative to the total amount of the polyisocyanate composition, the content of the residue of the aforementioned long-chain polyol component is 6% by mass or more and 30% by mass or less relative to the total amount of the polyisocyanate composition, the content of isocyanate groups in the polyisocyanate composition is 3% by mass or more and 24% by mass or less, and the molar ratio of isocyanurate groups to allophanate groups is 40:60 to 25:75.

[0019] [2] The polyisocyanate composition according to [1], wherein the long-chain polyol component is a polyether polyol.

[0020] [3] The polyisocyanate composition according to [1] or [2], wherein the isocyanate compound is an isocyanate prepolymer, the isocyanate prepolymer is a derivative of either 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 1 to 50 carbon atoms and a polyhydric alcohol having 2 to 50 carbon atoms, and the content of the monohydric alcohol residue or the polyhydric alcohol residue is 0.5% by mass to 30% by mass based on the total amount of the polyisocyanate composition.

[0021] [4] The polyisocyanate composition according to any one of [1] to [3], wherein the content of the ionic surfactant is 0.1% by mass or more and 10% by mass or less relative to the total amount of the polyisocyanate composition, and the content of water in the ionic surfactant is 1% by mass or less relative to the total amount of the ionic surfactant.

[0022] [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.

[0023] [6] A water-based two-component urethane coating composition comprising:

[0024] The polyisocyanate composition according to any one of [1] to [5]; and

[0025] The aqueous polyol has a hydroxyl value of 1 mgKOH / g or more and 300 mgKOH / g or less.

[0026] [7] The water-based two-component urethane coating composition according to [6], wherein the water-based polyol contains a fluorinated polyol or a silicone-based polyol.

[0027] Effects of the Invention

[0028] According to the present invention, a polyisocyanate composition and a water-based two-component urethane coating composition can be provided which have high compatibility with a main agent, a good pot life when mixed with the main agent, and good hardness and weather resistance when formed into a coating film. DETAILED DESCRIPTION

[0029] In addition, in this specification, "polyol" refers to a compound having two or more hydroxyl groups (-OH) in one molecule.

[0030] In the present specification, "polyisocyanate" refers to a reaction product obtained by bonding a plurality of monomer compounds having two or more isocyanate groups (-NCO).

[0031] In the present specification, unless otherwise specified, "(meth)acryloyl" includes methacryloyl and acryloyl, and "(meth)acrylate" includes methacrylate and acrylate.

[0032] <Polyisocyanate composition>

[0033] 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.

[0034] <<Isocyanate Compounds>>

[0035] The isocyanate compound is at least one selected from aliphatic diisocyanates, alicyclic diisocyanates, and isocyanate prepolymers thereof. In the present invention, aliphatic diisocyanates, alicyclic diisocyanates, and isocyanate prepolymers are collectively referred to as isocyanate compounds.

[0036] Examples of the aliphatic diisocyanate include tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (hereinafter referred to as HDI), trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0037] As alicyclic diisocyanates, for example, isophorone diisocyanate (hereinafter referred to as IPDI), xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate (hereinafter referred to as hydrogenated MDI), hydrogenated xylylene diisocyanate (hereinafter referred to as hydrogenated XDI), 1,4-diisocyanate cyclohexane, etc. can be cited. HDI, IPDI, hydrogenated MDI, and hydrogenated XDI are relatively cheap and easy to obtain industrially, so they are preferred. Among them, HDI is most preferred because the viscosity of the obtained polyisocyanate composition is easy to decrease.

[0038] Hereinafter, aliphatic diisocyanate and alicyclic diisocyanate are collectively referred to as raw material diisocyanate.

[0039] Isocyanate prepolymers are obtained by prepolymerizing raw material diisocyanates etc. using known techniques. Specifically, prepolymerization refers to subjecting raw material diisocyanates etc. to biuretization, isocyanurate conversion, urethanization, uretdione conversion, or allophanation conversion, which can be carried out using known techniques.

[0040] After the prepolymerization, it is safe and more preferable to remove the unreacted raw material diisocyanate. The raw material diisocyanate and the solvent used in the prepolymerization can be removed by, for example, a thin film distillation method or a solvent extraction method.

[0041] 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.

[0042] The alcohol is preferably at least one selected from a monohydric alcohol having 1 to 50 carbon atoms and a polyhydric alcohol having 2 to 50 carbon atoms.

[0043] The monoalcohol residue having 1 to 50 carbon atoms refers to a portion obtained by removing a hydrogen atom of a hydroxyl group possessed by the monoalcohol from the monoalcohol.

[0044] The polyol residue having 2 to 50 carbon atoms refers to a portion obtained by removing hydrogen atoms of hydroxyl groups possessed by the polyol from the polyol. By containing at least one of a monool residue and a polyol residue, better water dispersibility can be imparted to the polyisocyanate composition.

[0045] The 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. When the number of carbon atoms is in the range of 1 to 50, the viscosity can be designed appropriately.

[0046] Examples of the monohydric alcohol include saturated aliphatic alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, isopentanol, 1-hexanol, 2-hexanol, 3,3,5-trimethyl-1-hexanol, tridecanol, and pentadecyl alcohol; saturated cyclic aliphatic alcohols such as cyclopentanol, cyclohexanol, methylcyclohexanol, and trimethylcyclohexanol; unsaturated aliphatic alcohols such as propenol, butenol, hexenol, and 2-hydroxyethyl acrylate; ether bond-containing alcohols such as ethylene glycol monoalkyl ether and propylene glycol monoalkyl ether; ester bond-containing alcohols, etc. Among these, one kind may be used, or two or more kinds may be used in combination.

[0047] Polyol refers to an organic compound having two or more hydroxyl groups. The carbon number of the polyol is 2 to 50, preferably 2 to 30, and more preferably 2 to 15. If the carbon number is in the range of 2 to 50, it can be designed with an appropriate viscosity. The number of hydroxyl groups in the polyol is 2 to 10, preferably 2 to 6, and more preferably 2 to 4. If the number of hydroxyl groups is in the range of 2 to 10, it can have an appropriate viscosity and impart stretchability.

[0048] Examples of polyols are as follows.

[0049] Examples of the diol include hydrocarbon compounds such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol, 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.

[0050] Examples of the triol 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.

[0051] Examples of the tetravalent or higher alcohol include sugar alcohols such as tetraitols such as erythritol, pentitols such as xylitol, and hexitols such as sorbitol.

[0052] The monohydric alcohol and the polyhydric alcohol may be used alone or in combination of two or more.

[0053] Relative to the total amount of the polyisocyanate composition, the content of the residue of the monohydric alcohol or the residue of the polyol 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 further preferably 10% by mass or more and 20% by mass or less. If the content is above the lower limit, the dispersibility in water is improved. If the content is below the upper limit, it can be designed with the number of functional groups and viscosity of the appropriate isocyanate group.

[0054] 《Non-ionic hydrophilic ingredients》

[0055] The nonionic hydrophilic component has one hydroxyl group and contains 3 to 20 ethylene oxide repeating units.

[0056] The nonionic hydrophilic component is a component containing ethylene oxide repeating units in polyoxyalkylene ether alcohol. The number of hydroxyl groups of the hydrophilic component is at least one.

[0057] Examples of such compounds include polyethylene glycol, Pluronic (registered trademark) type polyalkylene glycol, etc. A preferred compound is polyethylene glycol monoalkyl ether, and a particularly preferred compound is polyethylene glycol monomethyl ether.

[0058] 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 ethylene oxide repeating units are 3 or more, sufficient emulsifying ability can be obtained. If the ethylene oxide repeating units are 20 or less, the crystallinity will not be too high and it is stable. By incorporating a nonionic hydrophilic component into the structure of the polyisocyanate composition, the ability to act as a surfactant is demonstrated.

[0059] In the polyisocyanate composition of the present invention, the content of the residue of the nonionic hydrophilic component 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, relative to the total amount of the polyisocyanate composition. The residue of the nonionic hydrophilic component refers to a portion obtained by removing the hydrogen atom of the hydroxyl group possessed by the nonionic hydrophilic component from the nonionic hydrophilic component.

[0060] 《Long-chain polyol ingredients》

[0061] The long-chain polyol is at least one selected from polyether polyols and polyester polyols having 2 to 4 hydroxyl groups and having a number average molecular weight of 1,000 to 15,000.

[0062] As the long-chain polyol component used in the present invention, one or a mixture of aliphatic hydrocarbon polyol, fluorine-containing polyol, polyether polyol, polyester polyol, polycarbonate polyol, epoxy resin, acrylic polyol and alkyd polyol can be used. Among them, polyether polyol and polyester polyol are preferred because the obtained polyisocyanate composition is easily dispersed in water, and polyether polyol is more preferred because it is more easily dispersed in water.

[0063] Examples of polyether polyols include: polyether polyols obtained by adding a single alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide, cyclohexane, styrene oxide or a mixture to a single polyhydroxy compound or a mixture using a strong alkaline catalyst such as hydroxides, alcohol salts, alkylamines of lithium, sodium, potassium or the like; further, polyether polyols obtained by reacting alkylene oxides with multifunctional compounds such as ethylenediamines; and so-called polymer polyols obtained by polymerizing acrylamide or the like using these polyethers as a medium.

[0064] Examples of the polyhydroxy compound include glycerol, trimethylolpropane, diglycerol, ditrimethylolpropane, pentaerythritol, dipentaerythritol, and the like; alcohol compounds such as erythritol, D-threitol, L-arabitol, ribitol, xylitol, sorbitol, mannitol, dulcitol, and rhamnitol; monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbitol, rhamnose, fucose, and deoxyribose; disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and melibiose; trisaccharides such as raffinose, gentiotriose, and melezitose; tetrasaccharides such as stachyose, and the like;

[0065] Examples of the polyester polyol include polyester polyols obtained by condensation reaction of a single dibasic acid or a mixture 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, and a single polyol or a mixture selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, glycerol, and the like; and polycaprolactone polyols such as those obtained by ring-opening polymerization of ε-caprolactone using a polyol; and polycarbonate polyols, etc.

[0066] The number average molecular weight of the long-chain polyol component is 1000 or more and 15000 or less, preferably 2000 or more and 12000 or less, and more preferably 3000 or more and 10000 or less. If the number average molecular weight is 1000 or more, stretchability can be imparted. If the number average molecular weight is 15000 or less, it can be designed with an appropriate viscosity.

[0067] The number of hydroxyl groups in the long-chain polyol is 2 or more and 4 or less, preferably 2 or more and 3 or less. If the number of hydroxyl groups is 2 or more, stretchability can be imparted, and if it is 4 or less, appropriate viscosity can be designed.

[0068] By incorporating a long-chain polyol component into the structure of the polyisocyanate composition, it is possible to impart stretchability to the water-based coating composition.

[0069] In the polyisocyanate composition of the present invention, the content of the residue of the long-chain polyol component is 6% by mass or more and 30% by mass or less relative to the total amount of the polyisocyanate composition. The residue of the long-chain polyol component refers to a portion obtained by removing the hydrogen atoms of the hydroxyl groups possessed by the long-chain polyol component from the long-chain polyol component.

[0070] In the polyisocyanate composition, the content of isocyanate groups is 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 main agent is high, and further, the hardness and weather resistance of the formed coating film are easily improved.

[0071] In the polyisocyanate composition, the molar ratio of isocyanurate group to allophanate group is 40:60 to 25:75. If the molar ratio of isocyanurate group to allophanate group is within the above range, the compatibility with the fluorine-based main agent is high, the pot life when mixed with the main agent is good, and the hardness and weather resistance of the coating film are improved.

[0072] The viscosity of the polyisocyanate composition of the present invention is, for example, 100 mP·s to 100,000 mP·s, preferably 100 mP·s to 50,000 mP·s, and more preferably 500 mP·s to 1,000 mP·s. When the viscosity is within the above range, the composition can be easily dispersed in water.

[0073] 《Ionic surfactants》

[0074] The polyisocyanate composition preferably further contains an ionic surfactant. In this case, the content of the ionic surfactant is preferably 0.1% by mass or more and 10% by mass or less relative to the total amount of the polyisocyanate composition.

[0075] The ionic surfactant preferably contains substantially no water. “Substantially no water” means that the water contained in the ionic surfactant reacts with the isocyanate group to such an extent that foaming, white turbidity and viscosity increase do not occur. Specifically, the water content relative to the total amount of the ionic surfactant is preferably 1% by mass or less.

[0076] By adding the ionic surfactant, the emulsification property is improved, the ability to protect the isocyanate groups from water is improved, and the isocyanate group retention rate of the aqueous dispersion and the pot life of the coating composition are improved.

[0077] The ionic surfactant used in the present invention can be an anionic surfactant or a cationic surfactant as long as it is appropriately selected according to the neutralization method of the aqueous polyol of the main agent used in the present invention. Specifically, when the aqueous polyol is neutralized by alkali, an anionic surfactant is preferably used, and when neutralized by acid, it is preferred because no aggregation occurs when a cationic surfactant is used. When the aqueous polyol is not neutralized, either an anionic surfactant or a cationic surfactant can be used.

[0078] Examples of anionic surfactants include alkylbenzene ammonium sulfonate, alkyl sodium disulfate, alkyl diphenyl ether sodium disulfonate, and dialkyl sodium sulfosuccinate. Examples of cationic surfactants include quaternary ammonium salts, pyridinium salts, and imidazolium salts. Examples of cationic surfactants include alkyl trimethylammonium bromide, alkyl pyridinium bromide, and imidazolinium laurate.

[0079] Relative to the total amount of the polyisocyanate composition, 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 further preferably 1.5% by mass or more and 7% by mass or less. If the content of the ionic surfactant is above the above lower limit, it is expected that the effect of dispersion stability can be achieved by mixing the ionic surfactant. If the content is below the above upper limit, the components that do not participate in crosslinking will not be too much, thereby becoming able to form a tough film.

[0080] 《Method for producing polyisocyanate composition》

[0081] 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.

[0082] The polyisocyanate composition of the present invention may be a composition obtained by subjecting a monohydric alcohol or a polyhydric alcohol to a urethanization reaction as required and, if required, to an allophanation reaction.

[0083] The polyisocyanate composition of the present invention may further contain an ionic surfactant as required.

[0084] The urethanization reaction refers to a reaction in which an isocyanate group and a hydroxyl group form a urethanate group. For example, an isocyanate compound and a compound having a hydroxyl group may be simply mixed to react, or a known urethanization catalyst such as dibutyltin laurate may be added as needed to cause the reaction. The reaction temperature is 20 to 200°C, preferably 40 to 180°C, and more preferably 60 to 160°C.

[0085] Allophanate reaction refers to a reaction in which an allophanate group is generated from an isocyanate group and a carbamate group. The allophanate reaction can be carried out using known techniques. For example, a method in which an isocyanate compound is mixed with a compound having a carbamate group and reacted at a temperature above 150°C, preferably above 160°C, can also be used. Alternatively, a method in which an isocyanate compound is mixed with a compound having a carbamate group and reacted using a known allophanate catalyst can also be used. The reaction when using an allophanate catalyst is, for example, above 20°C and below 200°C, preferably above 40°C and below 180°C, and more preferably above 60°C and below 160°C.

[0086] The urethanization reaction and the allophanation reaction may be performed simultaneously. Alternatively, the allophanation reaction may be started during the urethanization reaction, or the allophanation reaction may be performed after the urethanization reaction.

[0087] The isocyanate compound, the nonionic hydrophilic component, the long-chain polyol component, and, if necessary, the monohydric alcohol or polyhydric alcohol are subjected to urethanization reaction, and, if necessary, further subjected to allophanation reaction, can be carried out by any method, for example, the following method is available.

[0088] (Manufacturing method example 1)

[0089] Production method example 1 is a method in which a raw material diisocyanate is prepolymerized, a nonionic hydrophilic component, a long-chain polyol component, and at least one selected from a monool and a polyol are urethanized, and if necessary, allophanated.

[0090] (Manufacturing method example 2)

[0091] Production method example 2 is the following method: an isocyanate prepolymer is prepared from a nonionic hydrophilic component, at least one selected from a monohydric alcohol and a polyhydric alcohol as needed, and a raw material diisocyanate, a long-chain polyol component, at least one selected from a monohydric alcohol and a polyhydric alcohol as needed, is urethanized, and further allophanated as needed.

[0092] (Manufacturing method example 3)

[0093] Manufacturing method example 3 is the following method: an isocyanate prepolymer is prepared from a long-chain polyol component, at least one selected from a monohydric alcohol and a polyhydric alcohol as needed, and a raw material diisocyanate, a non-ionic hydrophilic component, at least one selected from a monohydric alcohol and a polyhydric alcohol as needed, is urethanized, and further allophanated as needed.

[0094] (Manufacturing method example 4)

[0095] Production method example 4 is a method of preparing an isocyanate prepolymer from at least one selected from monools and polyols and a raw material diisocyanate, urethanizing a nonionic hydrophilic component and a long-chain polyol component, and further allophanating the components as needed.

[0096] (Manufacturing method example 5)

[0097] Production method example 5 is a method of preparing a prepolymer from a nonionic hydrophilic component, a long-chain polyol component and a raw material diisocyanate, urethanizing at least one selected from a monool and a polyol as needed, and further allophanating as needed.

[0098] (Manufacturing method example 6)

[0099] Production method example 6 is a method of urethanizing a nonionic hydrophilic component, a long-chain polyol component, and, if necessary, at least one selected from monohydric alcohols and polyhydric alcohols with a raw material diisocyanate, and further allophanating if necessary.

[0100] Production methods 1, 2, 3, 4, and 5 are preferred from the viewpoint of production method and ease of production management.

[0101] Production method 6 is preferred from the viewpoint of lowering the viscosity of the obtained polyisocyanate composition.

[0102] In addition, an isocyanate compound, a nonionic hydrophilic component, a long-chain polyol component, and at least one of a monohydric alcohol and a polyol as required are added, and the resulting mixture is urethanized and / or allophanated to obtain a polyisocyanate composition, which can be further prepolymerized by a known technique as required.

[0103] It should be noted that these reactions may or may not use a solvent. When a solvent is used, it is preferred to select a solvent that is not reactive with isocyanate groups.

[0104] 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; or mixtures thereof. Among them, hydrophilic ether organic solvents and ester organic solvents having no active hydrogen such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol diacetate are particularly preferred.

[0105] After the reaction is finished, if necessary, unreacted raw material diisocyanate and solvent can also be removed. In the case of remaining unreacted raw material diisocyanate, it is preferably removed from the safety aspect. In addition, about ionic surfactant, when the urethanization reaction of isocyanate compound, nonionic hydrophilic component, long-chain polyol component and monohydric alcohol or polyol as needed is carried out allophanate reaction as needed, it can be mixed before reaction or while reacting or after reaction.

[0106] The polyisocyanate composition of the present invention may also be added with a urethanization catalyst as required. As the urethanization catalyst, a known compound may be used. For example, a tin compound such as dibutyltin dilaurate; a zirconium compound such as 2-ethylhexanoic acid zirconium salt, zirconium acetylacetonate; a zinc compound such as zinc 2-ethylhexanoate, etc. may be used. In particular, dibutyltin laurate is preferred because of its good curing acceleration effect.

[0107] <Water-based two-component urethane coating composition>

[0108] The present invention is a water-based 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.

[0109] The aqueous polyol used in the present invention includes all water-dispersible polyols and water-soluble polyols in the form of latex and emulsion.

[0110] The water-dispersible polyol is preferably a fluorine polyol or a silicone polyol.

[0111] 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 latex, styrene butadiene copolymer latex, acrylonitrile butadiene copolymer latex, polybutadiene copolymer latex, urethane acrylic emulsion, polyester latex, and the like.

[0112] As water-soluble polyols, for example, acrylate resins, polyester resins, polyurethane resins, vinyl acetate resins, polyvinyl alcohol resins, epoxy resins, polyalkylene oxide polyol resins, etc. can be cited. These can be obtained by known techniques. Latex and emulsion are excellent in water resistance compared with water-soluble polyols, so they are preferred. In particular, urethane emulsions, acrylic latexes, and fluorinated copolymer emulsions are excellent in weather resistance, so they are further preferred.

[0113] The hydroxyl value of the aqueous polyol used in the present invention is, for example, 1 mgKOH / g to 300 mgKOH / g, preferably 5 mgKOH / g to 150 mgKOH / g, and more preferably 10 mgKOH / g to 100 mgKOH / g.

[0114] If the hydroxyl value of the aqueous polyol is 1 mgKOH / g or more and 300 mgKOH / g or less, appropriate crosslinking is achieved in the coating composition, and a strong coating film can be formed. In addition, the hydroxyl value mentioned in the present invention is a value relative to the non-volatile component of the aqueous polyol.

[0115] 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.

[0116] In the present invention, the equivalent ratio of 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 can be achieved in the coating composition, and a strong coating film can be formed.

[0117] The polyisocyanate composition of the present invention can also be used by adding an organic solvent. The viscosity of the polyisocyanate composition added with an organic solvent decreases, and therefore, it has the effect of becoming easy to handle and easily dispersible in water. In this case, the organic solvent needs not to have a functional group that reacts with an isocyanate group. In addition, the organic solvent needs to be compatible with the polyisocyanate composition of the present invention.

[0118] Examples of such organic solvents include ester compounds such as ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, isoamyl 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.

[0119] 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.

[0120] Examples of the organic solvent include aromatic compounds such as benzene, toluene, xylene, ethylbenzene, butylbenzene, and p-cymene.

[0121] 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.

[0122] 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.

[0123] A urethanization catalyst may be added to the aqueous polyol used in the present invention as needed. As the urethanization catalyst, a known compound may be used. For example, tin compounds such as dibutyltin laurate; zirconium compounds such as 2-ethylhexanoic acid zirconium salt and zirconium acetylacetonate; zinc compounds such as zinc 2-ethylhexanoate, etc. may be used. In particular, a substance obtained by making a catalyst into an aqueous dispersion is easy to disperse in an aqueous polyol, so it is preferred. As a commercialized substance of such a compound, there is SCAT-1W (a substance obtained by making dibutyltin dilaurate into an aqueous dispersion; manufactured by Sankyo Organic Synthesis Co., Ltd.) and the like.

[0124] In the polyisocyanate composition and water-based two-component urethane coating composition of the present invention, pigments, dispersion stabilizers, viscosity modifiers, leveling agents, light stabilizers, antioxidants, ultraviolet absorbers, fillers, plasticizers, lubricants, curing accelerators, defoamers, etc. can be added as needed. In particular, if ultraviolet absorbers are used, weather resistance becomes good, so it is preferred. The polyisocyanate composition and water-based coating composition of the present invention have both high emulsification and stretchability, so they can be used for purposes that are difficult for conventional water-based polyisocyanate compositions, that is, the purposes that require the fragmentation, cracks, and deformation of other substrates to follow the concrete substrate. It is particularly suitable for coatings for building exterior packaging, coatings for building interiors, or coatings for automobile repair, and coatings for plastics. Furthermore, it can be applied to a wide range of fields such as other coatings, sealants, adhesives, inks, coating agents, injection molding agents, elastomers, foams, plastic raw materials, and fiber treatment agents.

[0125] Example

[0126] 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 at all.

[0127] [Materials used]

[0128] As the nonionic hydrophilic component, methoxy polyethylene glycol was used. The number of hydroxyl groups in methoxy polyethylene glycol was 1, and the number of ethylene oxide repeating units was 9. Hereinafter, methoxy polyethylene glycol is referred to as "N1".

[0129] As the long-chain polyol component, a trifunctional polyether polyol (polypropylene type, ethylene oxide added to the terminal) was used. The trifunctional polyether polyol had 3 hydroxyl groups and a number average molecular weight of 6400. Hereinafter, the trifunctional polyether polyol is referred to as "P1".

[0130] As the ionic surfactant, sodium dialkyl succinate sulfonate was used. Hereinafter, sodium dialkyl succinate sulfonate is referred to as "I1".

[0131] As the fluoropolyol, Lumiflon FE4400 (trade name, fluoro emulsion, manufactured by AGC Corporation) was used.

[0132] [Synthesis example 1]

[0133] The interior of a four-necked flask equipped with a stirrer, a thermometer, and a condenser was purged with nitrogen, 100 g of HDI and 10 g of 2-ethylhexanol were added, and the urethanization reaction was carried out at 80° C. for 1 hour under stirring. 0.1 g of tetramethylammonium decanoate was added as an isocyanurate and allophanate catalyst, and the reaction was allowed to proceed for about 3 hours, and 0.02 g of an aqueous solution of 85% solid content of phosphoric acid was added to stop the reaction. Unreacted HDI was removed using a downward 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 was referred to as isocyanurate polymer A1.

[0134] [Example 1]

[0135] 75 g of isocyanurate polymer A1, 15 g of N1, 10 g of P1, and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was performed at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, and the content of isocyanate groups was 11.1% and the viscosity was 1070 mPa·s. The polyisocyanate composition obtained in Example 1 was referred to as polyisocyanate composition 1.

[0136] [Synthesis example 2]

[0137] 67 g of isocyanurate polymer A1, 27 g of N1, and 6 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 3 hours. The obtained polyisocyanate composition was a light yellow liquid, the content of isocyanate groups was 9.02%, and the viscosity was 1052 mPa·s. The polyisocyanate composition obtained in Synthesis Example 2 was referred to as polyisocyanate composition A2.

[0138] [Synthesis example 3]

[0139] 71.4 g of isocyanurate polymer A1 and 28.6 g of P1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 80° C. for 1 hour. The obtained polyisocyanate composition was a transparent liquid, and the content of isocyanate groups was 12.3% and the viscosity was 1540 mPa·s. The polyisocyanate composition obtained in Synthesis Example 3 was referred to as polyisocyanate composition A3.

[0140] [Example 2]

[0141] Polyisocyanate composition A2 and polyisocyanate composition A3 were mixed at 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 having an isocyanate group content of 11.0% and a viscosity of 1600 mPa·s.

[0142] [Synthesis Example 4]

[0143] The interior of a four-necked flask equipped with a stirrer, a thermometer, and a condenser was purged with nitrogen, 100 g of HDI and 7.75 g of 2-ethylhexanol were added, and a urethanization reaction was carried out at 90° C. for 1 hour under stirring. After the temperature was raised to 130° C., 0.03 g of 2-ethylhexanoic acid zirconium oxysalt was added as an allophanation catalyst, and the reaction was carried out for about 2 hours. 0.28 g of a 2-ethyl-1-hexanol solution of pyrophosphoric acid (solid content 10%) (a substance obtained by diluting 2-ethyl-1-hexanol under the trade name "Phosphoric Acid (105%)" manufactured by Taihei Chemical Industry Co., Ltd.) was added, and the reaction was stopped by post-treatment at 130° C. for 1 hour. Unreacted HDI was removed using a downward flow thin film distillation apparatus at 160° C. (0.3 Torr) for the first time and 150° C. (0.1 Torr) for the second time. The obtained isocyanate prepolymer was a transparent liquid with a yield of 29 g and a viscosity of 110 mPa·s. The isocyanate group content was 17.2% and the monool content was 18% by mass. The isocyanurate polymer obtained in Synthesis Example 4 was designated as isocyanurate polymer A4.

[0144] [Example 3]

[0145] 74 g of isocyanurate polymer A1, 16.2 g of N1, 9.9 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 10.7%, and the viscosity was 1150 mPa·s. The polyisocyanate composition obtained in Example 3 was referred to as polyisocyanate composition 3.

[0146] [Example 4]

[0147] 74 g of isocyanurate polymer A1, 16.4 g of N1, 9.8 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 11.1%, and the viscosity was 1160 mPa·s. The polyisocyanate composition obtained in Example 4 was referred to as polyisocyanate composition 4.

[0148] [Example 5]

[0149] 85 g of isocyanurate polymer A1, 5 g of N1, 10 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 16.5%, and the viscosity was 1020 mPa·s. The polyisocyanate composition obtained in Example 5 was referred to as polyisocyanate composition 5.

[0150] [Example 6]

[0151] 70 g of isocyanurate polymer A1, 20 g of N1, 10 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, and the content of isocyanate groups was 9.7% and the viscosity was 2000 mPa·s. The polyisocyanate composition obtained in Example 6 was referred to as polyisocyanate composition 6.

[0152] [Example 7]

[0153] 79 g of isocyanurate polymer A1, 15 g of N1, 6 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, and the content of isocyanate groups was 13.1% and the viscosity was 700 mPa·s. The polyisocyanate composition obtained in Example 7 was referred to as polyisocyanate composition 7.

[0154] [Example 8]

[0155] 83.75 g of isocyanurate polymer A1, 9.75 g of N1, 6.5 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, and the content of isocyanate groups was 9.7% and the viscosity was 2520 mPa·s. The polyisocyanate composition obtained in Example 8 was referred to as polyisocyanate composition 8.

[0156] [Synthesis example 5]

[0157] The interior of a four-necked flask equipped with a stirrer, a thermometer, and a condenser was purged with nitrogen, 100 g of HDI and 0.11 g of tetramethylammonium decanoate as an isocyanurate catalyst were added, and the mixture was reacted for about 4 hours. 0.01 g of an aqueous solution of phosphoric acid having a solid content of 85% was added, and the reaction was stopped by post-treatment at 100°C for 1 hour. Unreacted HDI was removed using a downward 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%. The isocyanurate polymer was designated as isocyanurate polymer A5.

[0158] [Example 9]

[0159] 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 in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 11.5%, and the viscosity was 1050 mPa·s. The polyisocyanate composition obtained in Example 9 was referred to as polyisocyanate composition 9.

[0160] [Example 10]

[0161] The polyisocyanate composition 1 obtained in Example 1 and the isocyanurate polymer A4 obtained in Synthesis Example 4 were mixed at 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, and the content of isocyanate groups was 12.5% ​​and the viscosity was 700 mPa·s. The polyisocyanate composition obtained in Example 10 was referred to as polyisocyanate composition 10.

[0162] [Example 11]

[0163] 75 g of isocyanurate polymer A1, 15 g of N1 and 10 g of P1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, and the content of isocyanate groups was 11.1% and the viscosity was 1000 mPa·s. The polyisocyanate composition obtained in Example 11 was referred to as polyisocyanate composition 11.

[0164] [Comparative Example 1]

[0165] 88 g of isocyanurate polymer A1, 2 g of N1, 10 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 16.0%, and the viscosity was 980 mPa·s. The polyisocyanate composition obtained in Comparative Example 1 was referred to as polyisocyanate composition 1B.

[0166] [Comparative Example 2]

[0167] 79 g of isocyanurate polymer A1, 21 g of N1, 10 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, and the content of isocyanate groups was 8.7% and the viscosity was 2020 mPa·s. The polyisocyanate composition obtained in Comparative Example 2 was designated as polyisocyanate composition 2B.

[0168] [Comparative Example 3]

[0169] 79 g of isocyanurate polymer A1, 15 g of N1, 4 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 13.5%, and the viscosity was 650 mPa·s. The polyisocyanate composition obtained in Comparative Example 3 was referred to as polyisocyanate composition 3B.

[0170] [Comparative Example 4]

[0171] 57 g of isocyanurate polymer A1, 12 g of N1, 31 g of P1 and 2 g of I1 were mixed in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 7.72%, and the viscosity was 3307 mPa·s. The polyisocyanate composition obtained in Comparative Example 4 was designated as polyisocyanate composition 4B.

[0172] [Comparative Example 5]

[0173] 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 in the same apparatus as in Synthesis Example 1, and a urethanization reaction was carried out at 120° C. for 4 hours. The obtained polyisocyanate composition was a transparent liquid, the content of isocyanate groups was 11.4%, and the viscosity was 1040 mPa·s. The polyisocyanate composition obtained in Comparative Example 5 was referred to as polyisocyanate composition 5B.

[0174] [Comparative Example 6]

[0175] Isocyanurate polymer A1 and isocyanurate polymer A4 were mixed at 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, and the content of isocyanate groups was 13.4% and the viscosity was 670 mPa·s. The polyisocyanate composition obtained in Comparative Example 6 was referred to as polyisocyanate composition 6B.

[0176] [Determination of isocyanate group (NCO) content ratio]

[0177] The isocyanate group (NCO) content ratio (mass %) was determined by neutralizing the isocyanate groups in each polyisocyanate composition with an excess of 2N amine and then back-titrating with 1N hydrochloric acid.

[0178] [Viscosity measurement]

[0179] The viscosity of each polyisocyanate composition was measured at 25° C. using an E-type viscometer (manufactured by Tokimec Corporation). During the measurement, a standard rotor (1°34′×R24) was used. The rotation speed was as follows.

[0180] (Speed)

[0181] 100rpm (less than 128mPa·s)

[0182] 50rpm (128mPa·s or more and less than 256mPa·s)

[0183] 20rpm (256mPa·s or more and less than 640mPa·s)

[0184] 10rpm (640mPa·s or more and less than 1280mPa·s)

[0185] 5rpm (1280mPa·s or more and less than 2560mPa·s)

[0186] [Evaluation of compatibility with the main agent]

[0187] The polyisocyanate composition and the fluorine emulsion (trade name Lumiflon manufactured by AGC) are mixed in a ratio of isocyanate group / hydroxyl group equivalent ratio of 1.25, and water is added in a ratio of 47% of the solid content of the polyisocyanate composition and the polyol to obtain a water-based two-component urethane coating composition. The obtained water-based two-component urethane coating composition is applied on a glass plate, and after the prepared coating film is dried, the surface appearance is observed to confirm the compatibility of the polyisocyanate composition obtained in the examples and comparative examples as a curing agent with the acrylic polyol as a main agent. The compatibility with the main agent is evaluated according to the following evaluation criteria. The results are shown in Tables 1 to 2.

[0188] (Evaluation Criteria)

[0189] ◎: The overall appearance of the coating is transparent, without turbidity

[0190] ○: 10 to 30% of the coating area is cloudy in appearance

[0191] △: 30-50% of the coating area is cloudy in appearance

[0192] ×: The overall appearance of the coating film is cloudy and separated

[0193] [Evaluation of shelf life]

[0194] The polyisocyanate composition and the fluorine emulsion (trade name Lumiflon manufactured by AGC) were mixed at a ratio of isocyanate group / hydroxyl group equivalent ratio of 1.25, and water was added at a ratio of 47% of the solid content mass of the polyisocyanate composition and the polyol to obtain a water-based two-component urethane coating composition. The viscosity increase rate at 25°C when the initial viscosity of the obtained water-based two-component urethane coating composition after being stored at 23°C for 1 day was set as 100% was evaluated. The results are shown in Tables 1 and 2.

[0195] (Evaluation Criteria)

[0196] ◎: Viscosity increase rate is 100% or more and less than 150%

[0197] ○: Viscosity increase rate is 150% or more and less than 180%

[0198] △: Viscosity increase rate is 180% or more and less than 200%

[0199] ×: Viscosity increase rate is 200% or more

[0200] [Method for producing coating film]

[0201] The polyisocyanate composition and the water-based fluoropolyol (trade name Lumiflon manufactured by AGC Corporation) were mixed in a ratio of isocyanate group / hydroxyl group equivalent ratio of 1.25, and water was added in a ratio of 47% by weight of the solid content of the polyisocyanate composition and the polyol 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 coated plate with an applicator so that the film thickness after drying was 40 μm, and the coating was aged for 1 week under the conditions of 20° C. and 63% humidity.

[0202] [Evaluation of Weathering Resistance of Polyisocyanate Composition]

[0203] The coating film obtained by the method described in the above-mentioned [Method for preparing coating film] was evaluated for weather resistance. A double-panel weathering instrument (manufactured by Suga Test Instruments) was used for weather resistance evaluation. The evaluation conditions were in accordance with JIS D 0205, at an irradiation illumination of 30 W / m 2 The test was conducted under the conditions of a panel temperature of 60°C, an irradiation time of 4 hours and a condensation time of 4 hours each. The gloss retention rate at the exposure time of 5000 hours was 80% or more and was marked as ○, while the gloss retention rate less than 80% was marked as ×. The results are shown in Tables 1 and 2.

[0204] (Evaluation Criteria)

[0205] ◎: Gloss retention rate is more than 85%

[0206] ○: Gloss retention rate is 80% or more and less than 85%

[0207] △: Gloss retention rate is 70% or more and less than 80%

[0208] ×: Gloss retention rate is less than 70% [Table 1]

[0209]

[0210] [Table 2]

[0211]

[0212] It has been confirmed that the present invention can provide a polyisocyanate composition and a water-based two-component urethane coating composition which have high compatibility with a main agent, a good pot life when mixed with the main agent, and 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 aliphatic diisocyanates, alicyclic diisocyanates and isocyanate prepolymers thereof. The nonionic hydrophilic component has one hydroxyl group and contains 3 or more and 20 or less ethylene oxide repeating units, The long-chain polyol component is at least one selected from polyether polyols and polyester polyols having 2 or more and 4 or less hydroxyl groups and a number average molecular weight of 1,000 or more and 15,000 or less. The content of the residue of the nonionic hydrophilic component is 5% by mass or more and 20% by mass or less relative to the total amount of the polyisocyanate composition. The content of the residue of the long-chain polyol component is 6% by mass or more and 30% by mass or less relative to the total amount of the polyisocyanate composition. In the polyisocyanate composition, the content of the isocyanate group is 3% by mass or more and 24% by mass or less, and the molar ratio of the isocyanurate group to the allophanate group is 40:60 to 25:

75.

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

3. The polyisocyanate composition according to claim 1 or 2, wherein The isocyanate compound is an isocyanate prepolymer, and the isocyanate prepolymer is a derivative of either 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 1 to 50 carbon atoms and a polyhydric alcohol having 2 to 50 carbon atoms. The content of the monool residue or the polyol residue is 0.5% by mass or more and 30% by mass or less relative to the total amount of the polyisocyanate composition.

4. The polyisocyanate composition according to claim 1 or 2, wherein The content of the ionic surfactant is 0.1% by mass or more and 10% by mass or less relative to the total amount of the polyisocyanate composition. The ionic surfactant has a water content of 1% by mass or less relative to 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. A water-based two-component urethane coating composition comprising: The polyisocyanate composition according to claim 1 or 2; and The aqueous polyol has 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 aqueous polyol contains fluorine polyol or silicone polyol.

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