Polyisocyanate composition, polyaspartic coating composition, and coating film

Abstract

The present invention provides: a polyisocyanate composition which contains a polyisocyanate derived from at least one diisocyanate that is selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate and at least one polyol that is selected from the group consisting of a polyester polyol and a polyoxyalkylene polyol, in which the polyol has a number-average molecular weight of 200 to 2,000 inclusive and an average number of hydroxyl groups of 2 or 3, and the polyisocyanate contains a urethane group and an allophanate group per molecule in which the molar ratio of the allophanate group to the urethane group is 2 / 98 to 30 / 70 inclusisve; and others.

Description

[Technical Field]

[0001] The present invention relates to polyisocyanate compositions, polyaspartic coating compositions, and coating films. [Background technology]

[0002] Among polyurea coating compositions, aliphatic polyaspalatic coating compositions are formed from aspartic acid ester compounds containing amino groups and aliphatic and / or alicyclic polyisocyanate compositions containing isocyanate groups. The yellowing of the coating film due to ultraviolet exposure, a drawback of aromatic polyurea coating compositions, is significantly reduced, and they have been conventionally used in a wide range of applications such as various coatings, flooring materials, and waterproofing materials.

[0003] Aspartic acid ester compounds have lower viscosity compared to the main polyol component of polyurethane coating compositions, and because they significantly reduce the amount of diluent in polyaspartic coating compositions, high-solid and solvent-free formulations are possible. Furthermore, because the amino group of the aspartic acid ester compound reacts quickly with the isocyanate group of aliphatic and / or alicyclic polyisocyanates, polyaspartic coating compositions have the advantage of faster curing speed at room temperature and superior mechanical strength compared to polyurethane coating compositions.

[0004] For example, Patent Document 1 discloses a polyaspartic coating composition containing a polyaspartic acid ester compound and a polyisocyanate composition having a predetermined relationship in the content (mol%) of isocyanurate group, iminooxadiazinedione group, uretdione group, allophanate group, and biuret group. In this polyaspartic coating composition, the polyisocyanate composition has a low viscosity suitable for high-solid formulations and solvent-free formulations, and maintains curability and drying properties while the coating film using this polyaspartic coating composition also has excellent chemical resistance, hardness, and weather resistance. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2018 / 163953 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, while the polyaspartic coating composition proposed in Patent Document 1 achieves high solidity, it does not mention anything about suppressing the crystallization of the polyisocyanate composition used as a curing agent component, nor does it mention the elongation of the coating film obtained using the polyaspartic coating composition at low temperatures of around -20°C.

[0007] The present invention has been made in view of the above circumstances, and provides a polyisocyanate composition that has good viscosity, can suppress crystallization, and has good appearance, weather resistance and elongation at -20°C when formed into a coating film, as well as a polyaspartic coating composition and coating film using the polyisocyanate composition. [Means for solving the problem]

[0008] In other words, the present invention includes the following embodiment 1. (1) At least one diisocyanate selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, At least one polyol selected from the group consisting of polyester polyols and polyoxyalkylene polyols, It contains polyisocyanates derived from, The polyol has a number-average molecular weight of 200 or more and 2000 or less, and an average number of hydroxyl groups of 2 or 3. The aforementioned polyisocyanate contains a urethane group and an allophanate group in one molecule. A polyisocyanate composition having a molar ratio of allophanate groups to urethane groups of 2 / 98 or more and 30 / 70 or less. (2) The polyisocyanate composition according to (1), wherein the ratio of the molar amount of uretdione groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.3 mol% or more and 20 mol% or less. (3) The polyisocyanate composition according to (1) or (2), wherein the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.01 mol% or more and 20.00 mol% or less. (4) The polyisocyanate composition according to any one of (1) to (3), wherein the polyol comprises two polyester polyols having different structures from each other, or the polyester polyol and the polyoxyalkylene polyol. (5) The polyisocyanate composition according to any one of (1) to (4), wherein the content of the polyoxyalkylene polyol is 30% by mass or less relative to the total mass of the polyol. (6) The polyisocyanate composition according to any one of (1) to (5), wherein the content of polyols having an average number of hydroxyl groups of 3 is 30% by mass or less relative to the total mass of polyols. (7) A polyisocyanate composition according to any one of (1) to (6), which is a curing agent for polyaspartic coatings. (8) A polyaspartic coating composition comprising a polyisocyanate composition described in any one of (1) to (7) and an aspartic acid ester compound. (9) A coating film obtained by curing the polyaspartic coating composition described in (8). The present invention also includes the following embodiment 2. (1) A polyisocyanate derived from a diisocyanate, a first polyol, and a second polyol, The aforementioned diisocyanate is at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. The first polyol has a number average molecular weight of 200 or more and 2000 or less, an average number of hydroxyl groups of 2 or 3, and is at least one selected from the group consisting of polyester polyols and polyoxyalkylene polyols. The second polyol is a monool, diol or triol having a branched chain with 2 to 20 carbon atoms. A polyisocyanate composition in which the molar ratio of allophanate groups to urethane groups is 0 / 100 or more and 30 / 70 or less. (2) The polyisocyanate composition according to (1), wherein the content of the second polyol is 1% by mass or more and 30% by mass or less with respect to the total mass of the first polyol and the second polyol. (3) The polyisocyanate composition according to (1) or (2), wherein the second polyol is a diol having a branched chain with 3 to 20 carbon atoms. (4) The polyisocyanate composition according to any one of (1) to (3), wherein the molar ratio of allophanate groups to urethane groups is 2 / 98 or more and 30 / 70 or less. (5) The polyisocyanate composition according to any one of (1) to (4), wherein the ratio of the molar amount of uretdione groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.3 mol% or more and 20 mol% or less. (6) The polyisocyanate composition according to any one of (1) to (5), wherein the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.01 mol% or more and 20.00 mol% or less. (7) The polyisocyanate composition according to any one of (1) to (6), wherein the first polyol contains two types of the polyester polyols having different structures, or the polyester polyol and the polyoxyalkylene polyol. (8) The polyisocyanate composition according to any one of (1) to (7), wherein the content of the polyoxyalkylene polyol is 30% by mass or less with respect to the total mass of the first polyol and the second polyol. (9) The polyisocyanate composition according to claim 1, wherein the content of a polyol having an average number of hydroxyl groups of 3 is 30% by mass or less with respect to the total mass of the first polyol and the second polyol. (10) A polyisocyanate composition according to any one of (1) to (9), which is a curing agent for polyaspartic coatings. (11) A polyaspartic coating composition comprising a polyisocyanate composition described in any one of (1) to (10) and an aspartic acid ester compound. (12) A coating film obtained by curing the polyaspartic coating composition described in (11). [Effects of the Invention]

[0009] The polyisocyanate composition according to the above embodiment provides a polyisocyanate composition that has good viscosity, can suppress crystallization, and has good appearance, weather resistance, and elongation at -20°C when formed as a coating film. The polyaspartic coating composition according to the above embodiment contains the polyisocyanate composition and has good appearance, weather resistance, and elongation at -20°C when formed as a coating film. The coating film according to the above embodiment is formed by curing the polyaspartic coating composition and has good appearance, weather resistance, and elongation at -20°C. [Modes for carrying out the invention]

[0010] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"). However, the present invention is not limited to the following embodiments. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0011] In this specification, "polyol" means a compound having two or more hydroxyl groups (-OH).

[0012] In this specification, "polyisocyanate" means a reaction product obtained by bonding multiple monomer compounds (monomers) having one or more isocyanate groups (-NCO).

[0013] <Polyisocyanate composition according to Embodiment 1> The polyisocyanate composition of this embodiment comprises a polyisocyanate derived from at least one diisocyanate selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, and at least one polyol selected from the group consisting of polyester polyols and polyoxyalkylene polyols.

[0014] The polyol has a number-average molecular weight of 200 or more and 2000 or less, and an average number of hydroxyl groups of 2 or 3.

[0015] The aforementioned polyisocyanate contains a urethane group and an allophanate group in one molecule.

[0016] In the polyisocyanate composition of this embodiment, the molar ratio of allophanate groups to urethane groups (allophanate group / urethane group molar ratio) is preferably 2 / 98 or more and 30 / 70 or less, preferably 3 / 97 or more and 30 / 70 or less, and more preferably 5 / 95 or more and 20 / 80 or less. By having an allophanate group / urethane group molar ratio of 2 / 98 or more than the above lower limit, crystallization can be suppressed, and the polyisocyanate composition of this embodiment can be incorporated into paint compositions, particularly polyaspartic paint compositions, as a uniform curing agent. This results in a coating film with excellent curability, surface appearance, and elongation at low temperatures of around -20°C. On the other hand, by having an allophanate group / urethane group molar ratio of 2 / 98 or less than the above upper limit, a coating film with excellent weather resistance can be obtained.

[0017] The molar ratio of allophanate groups to urethane groups is, for example, 13 It can be calculated by 13C-NMR spectroscopy. Specifically, it can be calculated using the method described in the examples below.

[0018] The polyisocyanate composition of this embodiment, having the above configuration, provides a coating film with good viscosity, suppression of crystallization, and good appearance, weather resistance, and elongation at -20°C.

[0019] The polyisocyanate composition of this embodiment can be suitably used as a curing agent for polyaspartic coating compositions mainly composed of aspartic acid ester compounds, i.e., as a curing agent for polyaspartic coatings.

[0020] Next, each component contained in the polyisocyanate composition of this embodiment will be described in detail below.

[0021] <Polyisocyanate> The polyisocyanate contained in the polyisocyanate composition of this embodiment is derived from at least one diisocyanate selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, and at least one polyol selected from the group consisting of polyester polyols and polyoxyalkylene polyols. In other words, the polyisocyanate is a reaction product of the above diisocyanate and the above polyol.

[0022] Furthermore, polyisocyanates contain both urethane groups and allophanate groups in a single molecule. Urethane groups are formed by the reaction of the isocyanate group of diisocyanate with the hydroxyl group of polyol. Allophanate groups are formed by the reaction of a urethane group with the isocyanate group of diisocyanate, or by the reaction of two isocyanate groups of diisocyanate with one hydroxyl group of polyol.

[0023] Polyisocyanates may have other functional groups in addition to urethane and allophanate groups, such as isocyanurate and uretdione groups.

[0024] Alternatively, the polyisocyanate composition of this embodiment may further include, in addition to a polyisocyanate having a urethane group and an allophanate group in its molecule, a polyisocyanate having one of the urethane group and the allophanate group, or a polyisocyanate having other functional groups such as an isocyanurate group or a uretdione group, either alone or in combination of two or more.

[0025] In the polyisocyanate composition of this embodiment, the ratio of the molar amount of uretdione groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is preferably 0.3 mol% or more and 20 mol% or less, more preferably 1 mol% or more and 10 mol% or less, and even more preferably 2 mol% or more and 10 mol% or less. When the ratio of the molar amount of uretdione groups is above the lower limit, the viscosity of the polyisocyanate composition becomes lower, and it can be made into a high-solids coating. On the other hand, when the ratio of the molar amount of uretdione groups is below the upper limit, the low-temperature elongation when it is made into a coating film can be made better.

[0026] In the polyisocyanate composition of this embodiment, the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is preferably 0.01 mol% to 20.00 mol%, more preferably 0.01 mol% to 10.00 mol%, even more preferably 0.01 mol% to 5.00 mol%, and particularly preferably 0.01 mol% to 3.00 mol%. By keeping the molar ratio of isocyanurate groups below the above upper limit, the low-temperature elongation of the coating film can be improved. On the other hand, the lower the molar amount of isocyanurate groups, the better the low-temperature elongation of the coating film can be.

[0027] The molar amounts of each functional group in a polyisocyanate composition are, for example, 13 The molar amounts of the specific functional groups can be measured by 13C-NMR spectroscopy, and the molar proportion of each functional group can be calculated using the calculated molar amounts of each functional group. Specifically, it can be calculated using the method described in the examples below.

[0028] [Diisocyanate] Diisocyanates are at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

[0029] Examples of aliphatic diisocyanates include, but are not limited to, 1,4-diisocyanatobutane, 1,5-diisocyanatopentane (hereinafter sometimes abbreviated as "PDI"), ethyl(2,6-diisocyanato)hexanoate, 1,6-diisocyanatohexane (hereinafter sometimes abbreviated as "HDI"), 1,9-diisocyanatononane, 1,12-diisocyanatododecane, and 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane. These aliphatic diisocyanates may be used individually or in combination of two or more.

[0030] Examples of alicyclic diisocyanates include, but are not limited to, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (hereinafter sometimes abbreviated as "hydrogenated XDI"), 1,3- or 1,4-diisocyanatocyclohexane, 3,5,5-trimethyl1-isocyanato-3-(isocyanatomethyl)cyclohexane (hereinafter sometimes abbreviated as "IPDI"), 4-4'-diisocyanato-dicyclohexylmethane (hereinafter sometimes abbreviated as "hydrogenated MDI"), and 2,5- or 2,6-diisocyanatomethylnorbornane. These alicyclic diisocyanates may be used individually or in combination of two or more.

[0031] These aliphatic diisocyanates and alicyclic diisocyanates may be used individually, or two or more aliphatic diisocyanates and alicyclic diisocyanates may be used in combination.

[0032] Among these, PDI, HDI, IPDI, hydrogenated XDI, or hydrogenated MDI are preferred as diisocyanates, PDI, HDI, or IPDI are more preferred, and HDI is even more preferred.

[0033] In addition to the diisocyanate described above, isocyanate monomers such as those shown below may also be used in the production of polyisocyanates. (1) Aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and m-tetramethylxylylene diisocyanate (TMXDI). (2) Triisocyanates such as 4-isocyanate methyl-1,8-octamethylene diisocyanate (hereinafter sometimes referred to as "NTI"), 1,3,6-hexamethylene triisocyanate (hereinafter sometimes referred to as "HTI"), bis(2-isocyanatoethyl)2-isocyanatoglutarate (hereinafter sometimes referred to as "GTI"), and lysine triisocyanate (hereinafter sometimes referred to as "LTI").

[0034] [Polyol] The number-average molecular weight of the polyol is 200 to 2000, preferably 300 to 1500, more preferably 350 to 1200, and even more preferably 400 to 1000. Having a number-average molecular weight of the polyol above the lower limit results in a coating film with high and good elongation at low temperatures of around -20°C. On the other hand, having a number-average molecular weight of the polyol below the upper limit allows the viscosity of the polyisocyanate composition to be kept low, enabling the production of a high-solids coating.

[0035] The number-average molecular weight (Mn) of a polyol is, for example, the number-average molecular weight of polystyrene measured by GPC. Furthermore, when two or more polyols are used in mixture, the number-average molecular weight of the mixture is calculated.

[0036] The viscosity of the polyol at 25°C is preferably 90 mPa·s to 3000 mPa·s, more preferably 100 mPa·s to 2500 mPa·s, and even more preferably 100 mPa·s to 2000 mPa·s. A viscosity of the polyol above the lower limit results in greater and better elongation at low temperatures of around -20°C when applied as a coating film. On the other hand, a viscosity of the polyol below the upper limit allows for a lower viscosity of the polyisocyanate composition, enabling the production of a high-solids coating.

[0037] The viscosity of the polyol at 25°C can be measured by the method described in the examples below.

[0038] The average number of hydroxyl groups in a polyol is 2 or 3.

[0039] By using a polyol with an average number of hydroxyl groups of 2, the viscosity of the polyisocyanate composition can be reduced, resulting in a high-solids coating. Furthermore, because the polyisocyanate has fewer branches, the elongation at low temperatures of around -20°C when applied as a coating film is greater, resulting in a superior coating.

[0040] Furthermore, by using a polyol with an average number of hydroxyl groups of 3, crystallization can be further suppressed, and the polyisocyanate composition of this embodiment can be incorporated into paint compositions, particularly polyaspartic paint compositions, as a uniform curing agent. This results in a coating film with superior curability and surface appearance.

[0041] The polyol is at least one selected from the group consisting of polyester polyols and polyoxyalkylene polyols.

[0042] (Polyester polyol) The number-average molecular weight of the polyester polyol can be between 200 and 2000, preferably between 300 and 1500, more preferably between 350 and 1200, and even more preferably between 400 and 1000.

[0043] Examples of polyester polyols include either (1) or (2) below. (1) A polyester polyol obtained by a condensation reaction of a dibasic acid alone or a mixture of two or more dibasic acids with a dihydric or higher alcohol alone or a mixture of two or more dihydric alcohols. (2) Polycaprolactone polyol obtained by ring-opening polymerization of ε-caprolactone with a divalent or higher alcohol.

[0044] Examples of the aforementioned dibasic acids include succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic anhydride, maleic acid, phthalic acid, glutaric acid, speric acid, azelaic acid, sebacic acid, decandioic acid, itaconic acid, itaconic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, and other carboxylic acids.

[0045] Examples of the aforementioned alcohols with a valency of 2 or higher include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, 2-ethyl-1,3-hexanediol, trimethylolpropane, glycerin, pentaerythritol, 2-methylolpropanediol, ethoxylated trimethylolpropane, 1,3-propanediol, pentane-1,5-diol, heptane-1,7-diol, octane-1,8-diol, nonane-1,9-diol, decane-1,1 Examples include 0-diol, dodecane-1,12-diol, cyclohexane-1,4-dimethanol, 4,4'-(1-methylethylidene)biscyclohexanol, 1,1,1-trimethylolethane, hexane-1,2,6-triol, dipropylene glycol, propane-1,2-diol, butane-1,3-diol, hexane-1,2-diol, 2-methylpentane-2,4-diol, 3-methyl-1,5-pentanediol, octane-1,2-diol, 2-butyl-2-ethylpropane-1,3-diol, decane-1,2-diol, and 2-methyl-1,3-propanediol.

[0046] Among these, bifunctional or trifunctional polycaprolactone polyols are preferred as polyester polyols.

[0047] Examples of commercially available bifunctional polycaprolactone polyols include Daicel's product names "Praxel 205H" (number average molecular weight 530), "Praxel 210" (number average molecular weight 1000), "Praxel 210CP" (number average molecular weight 1000), "Praxel 212" (number average molecular weight 1250), "Praxel 212CP" (number average molecular weight 1250), "Praxel 220" (number average molecular weight 2000), and "Praxel 220CPB" (number average molecular weight 2000). Examples include "Praxel 220CPT" (number average molecular weight 2000); Ingevity's product names "Capa2043" (number average molecular weight 400, viscosity at 25°C 246 mPa·s), "Capa2054" (number average molecular weight 550, viscosity at 25°C 360 mPa·s), "Capa2085" (number average molecular weight 830, viscosity at 25°C 627 mPa·s), and "Capa2067A" (number average molecular weight 650, viscosity at 25°C 493 mPa·s).

[0048] In addition, commercially available bifunctional polyester polyols such as "Kuraray Polyol P-510" (number average molecular weight 500, viscosity at 25°C 540 mPa·s) manufactured by Kuraray Co., Ltd., and "ODX2406" (number average molecular weight 440, viscosity at 25°C 460 mPa·s) manufactured by DIC Corporation may be used.

[0049] Examples of commercially available trifunctional polycaprolactone polyols include Daicel's "Praxel 305" (number average molecular weight 550), "Praxel 308" (number average molecular weight 850), "Praxel 309" (number average molecular weight 900), "Praxel 312" (number average molecular weight 1250), and "Praxel 320" (number average molecular weight 2000); DIC's "ODX2542C" (number average molecular weight 850); and Ingevity's "Capa3050" (number average molecular weight 540, viscosity at 60°C 160 mPa·s) and "Capa23091" (number average molecular weight 900, viscosity at 60°C 165 mPa·s).

[0050] (Polyoxyalkylene polyol) Polyoxyalkylene polyols are -O(CH2) n This polyol contains repeating units represented by - and is divalent to tetravalent, and can be derived from a divalent to tetravalent alcohol and ethylene oxide, propylene oxide, tetrahydrofuran, etc. Furthermore, although not particularly limited, it can be obtained by cationic polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc., using a divalent to tetravalent alcohol as an initiator in the presence of a catalyst.

[0051] The number-average molecular weight of the polyoxyalkylene polyol is preferably 200 to 2000, more preferably 200 to 1500, and even more preferably 200 to 1000.

[0052] As initiators, dihydric alcohols include: ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,3-butylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, pentaerythritol, 2-methylolpropanediol, 2-ethyl-1,3-hexanediol, 1,3-propanediol, pentane-1,5-diol, heptane-1,7-diol, octane-1,8-diol, nonane-1,9-diol, decane-1,10-diol, dodecane-1,12-diol, and cyclohexane-1,4-dimethyl Examples of polyisocyanates used include: 4,4'-(1-methylethylidene)biscyclohexanol, 1,1,1-trimethylolethane, hexane-1,2,6-triol, dipropylene glycol, propane-1,2-diol, butane-1,3-diol, hexane-1,2-diol, 2-methylpentane-2,4-diol, 3-methyl-1,5-pentanediol, octane-1,2-diol, 2-butyl-2-ethylpropane-1,3-diol, decane-1,2-diol, 2-methyl-1,3-propanediol, etc. Trihydric alcohols: glycerin, trimethylolpropane, etc. Tetrahydric alcohols: pentaerythritol, etc. From the viewpoint of obtaining a low viscosity polyisocyanate component, branched polyhydric alcohols are preferred.

[0053] As catalysts, hydroxides such as lithium, sodium, and potassium, or strongly basic catalysts such as alkoxides and alkylamines can be used.

[0054] Cationic polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc. is preferably carried out in a nitrogen gas atmosphere, with the ethylene oxide, propylene oxide, tetrahydrofuran, etc. and the above-mentioned initiator set in a molar ratio to achieve a predetermined molecular weight, and then 0.1 ppm to 100 ppm of catalyst added to the ethylene oxide, propylene oxide, tetrahydrofuran, etc., and reacted at a temperature of 150°C to 200°C for 4 to 10 hours.

[0055] Examples of commercially available bifunctional polyoxyalkylene polyols include "ECOTRION H1000" (number average molecular weight 1000, viscosity at 25°C 489 mPa·s) and "ECOTRION H2000" (number average molecular weight 2000, viscosity at 25°C 1701 mPa·s) from SK Chemicals; "Velvet H250" (number average molecular weight 227, viscosity at 25°C 107 mPa·s) from Allessa; and "BioPTMG650" (number average molecular weight 655, viscosity at 25°C 351 mPa·s) from Mitsubishi Chemical Corporation.

[0056] The polyol preferably comprises two polyester polyols with different structures, or a polyester polyol and a polyoxyalkylene polyol. By including the above combination of two polyols, crystallization can be further suppressed.

[0057] Furthermore, when using two polyester polyols with different structures, or a combination of a polyester polyol and a polyoxyalkylene polyol, the blending ratio can be adjusted as appropriate so that the number average molecular weight falls within the above range. These polyester polyols can be blended in mass ratios such as 3:1 to 1:3, 2:1 to 1:2, and 1.5:1 to 1:1.5.

[0058] The polyoxyalkylene polyol content is preferably 30% by mass or less, more preferably 28% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less, based on the total mass of the polyol. By keeping the polyoxyalkylene polyol content below the above upper limit, the weather resistance of the coating film can be improved. The lower limit of the polyoxyalkylene polyol content is not particularly limited and can be, for example, 0%, 1%, 2%, 3%, etc.

[0059] When using a combination of a polyol with an average number of hydroxyl groups of 2 and a polyol with an average number of hydroxyl groups of 3, it is preferable that the polyol with an average number of hydroxyl groups of 2 is present in greater proportion than the polyol with an average number of hydroxyl groups of 3. Specifically, the content of the polyol with an average number of hydroxyl groups of 3 is preferably 30% by mass or less, more preferably 28% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less, relative to the total mass of the polyols. By keeping the content of the polyol with an average number of hydroxyl groups of 3 below the above upper limit, the elongation at low temperatures of around -20°C when used as a coating film can be improved. The lower limit of the content of the polyol with an average number of hydroxyl groups of 3 is not particularly limited and can be, for example, 0%, 1%, 2%, 3%, etc.

[0060] <Other ingredients> The polyisocyanate composition of this embodiment preferably contains one or more selected from the group consisting of ultraviolet absorbers and light stabilizers. Including ultraviolet absorbers and light stabilizers results in a coating film with superior weather resistance.

[0061] While not particularly limited, examples of UV absorbers include benzotriazole compounds, triazine compounds, benzophenone compounds, and cyanoacrylate compounds.

[0062] Benzotriazole compounds are not particularly limited, but examples include the trade names Tinuvin P·PS·99-2·213·234·326·329·360·384-2·571·900·928·970·1130 manufactured by BASF Japan Ltd.; Adeka Stab LA-24·29·31RG·31G·32·36·36RG·F70 manufactured by ADEKA Corporation; and EVERSORB 70·71·72·73·74·75·76·77·78·79·80·81·82·88·89·109·234 manufactured by Taiwan Yongguang Chemical Industry Co., Ltd.

[0063] Triazine compounds are not particularly limited, but examples include the trade names Tinuvin 400, 400-DW, 405, 460, 477, 479, 479-DW, 1577ED, and 1600 manufactured by BASF Japan Ltd., and EVERSORB 40, 41FD, and 45 manufactured by Taiwan Yongguang Chemical Industry Co., Ltd.

[0064] Benzophenone compounds are not particularly limited, but examples include Chimassorb 81·81FL and Uvinul 3049·3050 from BASF Japan Ltd.; Adeka Stab 1413 from ADEKA Corporation; and EVERSORB 10·11·12·51·52 from Taiwan Yongguang Chemical Industry Co., Ltd.

[0065] The cyanoacrylate compounds are not particularly limited, but examples include the trade names Uvinul 3030FF, 3035, and 3039 manufactured by BASF Japan Ltd.

[0066] From the viewpoint of maintaining the weather resistance of the coating film over a long period of time, benzotriazole compounds, triazine compounds, or benzophenone compounds are preferred, and benzotriazole compounds or triazine compounds are more preferred.

[0067] While not particularly limited, examples of light stabilizers include hindered amine compounds.

[0068] Hindered amine compounds are not particularly limited, but examples include the trade names Tinuvin 111FDL, 123, 123-DW, PA144, 152, 249, 292, 783FDL, and 765 manufactured by BASF Japan Ltd.; Adeka Stab LA-52, 57, 63P, 68, 72, 77Y, 77G, 81, and 402AF manufactured by ADEKA Corporation; and EVERSORB 60, 61, 90, 91FD, 93, 94FD, 95, 765, and S02 manufactured by Taiwan Yongguang Chemical Industry Co., Ltd.

[0069] UV absorbers and light stabilizers may be used individually or in combination of two or more types.

[0070] The total amount of UV absorber and light stabilizer added is preferably 10 ppm by mass or more and 15,000 ppm by mass or less, relative to the total mass of the polyisocyanate composition.

[0071] The polyisocyanate composition of this embodiment may further contain an antioxidant.

[0072] Examples of antioxidants include hindered phenol-based antioxidants.

[0073] Hindered phenol antioxidants are not particularly limited, but examples include dibutylhydroxytoluene (hereinafter sometimes abbreviated as "BHT"); BASF brand names "Irganox 1010", "Irganox 1135", "Irganox 1330", "Irganox 3114", "Irganox 565", and "Irganox 1520L"; and ADEKA Corporation brand names "ADEKA Stab AO-20", "ADEKA Stab AO-30", "ADEKA Stab AO-50", "ADEKA Stab AO-60", and "ADEKA Stab AO-80".

[0074] <Method for producing polyisocyanate composition> The polyisocyanate composition of this embodiment can be obtained by simultaneously carrying out a urethane reaction to form urethane groups and an allophanate reaction to form allophanate groups in the presence of an excess of diisocyanate, and then removing the unreacted diisocyanate monomer after the reaction is complete.

[0075] The urethane reaction can be carried out by mixing an excess of diisocyanate with a polyol and adding a urethane reaction catalyst as needed.

[0076] The urethane reaction catalyst is not particularly limited, but examples include tin-based compounds, zinc-based compounds, amine-based compounds, and the like.

[0077] The urethane reaction temperature is preferably 50°C to 160°C, and more preferably 60°C to 120°C.

[0078] By keeping the urethane reaction temperature below the above upper limit, discoloration of the polyisocyanate tends to be more effectively suppressed.

[0079] Furthermore, the urethane reaction time is preferably 30 minutes to 4 hours, more preferably 1 hour to 3 hours, and even more preferably 1 hour to 2 hours.

[0080] The ratio of the molar amount of isocyanate groups in the isocyanate monomer to the molar amount of hydroxyl groups in the alcohol (molar ratio of isocyanate groups to hydroxyl groups) is preferably between 2 / 1 and 50 / 1. A molar ratio above the lower limit allows for a lower viscosity polyisocyanate. A molar ratio below the upper limit allows for a higher yield of urethane group-containing polyisocyanate.

[0081] The allophanate reaction can be carried out after the urethane reaction described above, by reacting the formed urethane group with an isocyanate group, or by reacting two isocyanate groups with one hydroxyl group. The allophanate reaction may also be carried out using an allophanate reaction catalyst.

[0082] The allophanate reaction catalyst is not limited to the following, but examples include alkyl carboxylates of tin, lead, zinc, bismuth, zirconium, zirconyl, etc.

[0083] Examples of alkyl carboxylates of tin (organotin compounds) include tin 2-ethylhexanoate and dibutyltin dilaurate.

[0084] Examples of alkyl carboxylates of lead (organic lead compounds) include lead 2-ethylhexanoate.

[0085] Examples of zinc alkyl carboxylates (organozinc compounds) include zinc 2-ethylhexanoate.

[0086] Examples of alkyl carboxylate salts of bismuth include bismuth 2-ethylhexanoate.

[0087] Examples of alkyl carboxylate salts of zirconium include zirconium 2-ethylhexanoate.

[0088] Examples of alkyl carboxylate salts of zirconyl include zirconyl 2-ethylhexanoate.

[0089] These catalysts can be used individually or in combination of two or more types.

[0090] The lower limit of the amount of allophanate reaction catalyst used is preferably 10 ppm by mass, more preferably 15 ppm by mass, even more preferably 18 ppm by mass, and particularly preferably 20 ppm by mass, relative to the mass of the charged isocyanate monomer.

[0091] The upper limit of the amount of allophanate reaction catalyst used as described above is preferably 1000 ppm by mass, more preferably 800 ppm by mass, even more preferably 500 ppm by mass, and particularly preferably 300 ppm by mass, relative to the mass of the charged isocyanate monomer.

[0092] In other words, the amount of allophanate reaction catalyst used is preferably 10 ppm to 1000 ppm by mass, more preferably 15 ppm to 800 ppm by mass, even more preferably 18 ppm to 500 ppm by mass, and particularly preferably 20 ppm to 300 ppm by mass, relative to the mass of the charged isocyanate monomer.

[0093] Furthermore, the lower limit of the allophanate reaction temperature is preferably 80°C, and more preferably 100°C.

[0094] Furthermore, the upper limit of the allophanate reaction temperature is preferably 200°C, and more preferably 180°C.

[0095] In other words, the allophanate reaction temperature is preferably 80°C to 200°C, and more preferably 100°C to 180°C.

[0096] By keeping the allophanate reaction temperature above the lower limit, the reaction rate can be further improved. By keeping the allophanate reaction temperature below the upper limit, discoloration of the polyisocyanate tends to be more effectively suppressed.

[0097] In the allophanate reaction, the molar ratio of allophanate groups to urethane groups (allophanate group / urethane group molar ratio) can be adjusted to the above range by confirming the increase in the refractive index of the reaction solution. The reaction is stopped when the refractive index of the reaction solution reaches the desired value.

[0098] <Properties of Polyisocyanate Compositions> The isocyanate group content of the polyisocyanate composition of this embodiment is preferably 5.0% by mass or more and 20.0% by mass or less, more preferably 6.0% by mass or more and 18.0% by mass or less, even more preferably 7.0% by mass or more and 15.0% by mass or less, particularly preferably 7.5% by mass or more and 13.0% by mass or less, and most preferably 8.5% by mass or more and 12.5% ​​by mass or less. By having an isocyanate group content above the lower limit, the concentration of urea bonds that serve as bonding sites in the coating film can be increased, resulting in better weather resistance when applied as a coating film. On the other hand, by having an isocyanate group content below the upper limit, it is possible to suppress the concentration of urea bonds that serve as bonding sites in the coating film from rising too high, resulting in good elongation at low temperatures of around -20°C when applied as a coating film.

[0099] The isocyanate group content can be measured using the method described in the examples below.

[0100] The lower limit of the viscosity of the polyisocyanate composition of this embodiment at 25°C is preferably 100 mPa·s, more preferably 500 mPa·s, even more preferably 700 mPa·s, and particularly preferably 800 mPa·s. On the other hand, the upper limit of viscosity is preferably 3000 mPa·s, more preferably 2500 mPa·s, even more preferably 2000 mPa·s, and particularly preferably 1700 mPa·s.

[0101] In other words, the viscosity of the polyisocyanate composition of this embodiment at 25°C is preferably 100 mPa·s or more and 3000 mPa·s or less, more preferably 500 mPa·s or more and 2500 mPa·s or less, even more preferably 700 mPa·s or more and 2000 mPa·s or less, and particularly preferably 800 mPa·s or more and 1700 mPa·s or less.

[0102] When the viscosity is above the lower limit mentioned above, it tends to be possible to better maintain workability during paint compounding. On the other hand, when the viscosity is below the upper limit mentioned above, the amount of solvent used when preparing the polyaspartic paint composition can be further reduced.

[0103] Viscosity can be measured by the method described in the examples below.

[0104] <Polyisocyanate composition according to Embodiment 2> The polyisocyanate composition of this embodiment comprises a diisocyanate, a first polyol, and a polyisocyanate derived from a second polyol.

[0105] The diisocyanate is at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

[0106] The first polyol has a number-average molecular weight of 200 or more and 2000 or less, an average number of hydroxyl groups of 2 or 3, and is at least one selected from the group consisting of polyester polyols and polyoxyalkylene polyols.

[0107] The second polyol is a monool, diol, or triol having a branched chain with 2 to 20 carbon atoms.

[0108] The molar ratio of allophanate groups to urethane groups (allophanate group / urethane group molar ratio) is preferably 0 / 100 or more and 30 / 70 or less, preferably 2 / 98 or more and 30 / 70 or less, preferably 3 / 97 or more and 30 / 70 or less, and more preferably 5 / 95 or more and 20 / 80 or less. By having an allophanate group / urethane group molar ratio above the lower limit, crystallization can be further suppressed, and the polyisocyanate composition of this embodiment can be incorporated into paint compositions, particularly polyaspartic paint compositions, as a uniform curing agent. This results in a coating film with excellent curability and surface appearance. On the other hand, by having an allophanate group / urethane group molar ratio below the upper limit, a coating film with excellent weather resistance can be obtained.

[0109] The molar ratio of allophanate groups to urethane groups is, for example, 13 It can be calculated by 13C-NMR spectroscopy. Specifically, it can be calculated using the method described in the examples below.

[0110] The polyisocyanate composition of this embodiment, having the above configuration, provides a coating film with good viscosity, suppression of crystallization, and good appearance, weather resistance, and elongation at -20°C.

[0111] The polyisocyanate composition of this embodiment can be suitably used as a curing agent for polyaspartic coating compositions mainly composed of aspartic acid ester compounds, i.e., as a curing agent for polyaspartic coatings.

[0112] Next, each component contained in the polyisocyanate composition of this embodiment will be described in detail below.

[0113] <Polyisocyanate> The polyisocyanate contained in the polyisocyanate composition of this embodiment is derived from a diisocyanate, a first polyol, and a second polyol. That is, the polyisocyanate is a reaction product of the diisocyanate, the first polyol, and the second polyol.

[0114] Furthermore, the polyisocyanate composition of this embodiment may be a mixture of a polyisocyanate which is a reaction product of diisocyanate, a first polyol, and a second polyol, a polyisocyanate which is a reaction product of diisocyanate and a first polyol, or a polyisocyanate which is a reaction product of diisocyanate and a second polyol.

[0115] Furthermore, the polyisocyanate contains a urethane group. The urethane group is formed by the reaction of the isocyanate group of the diisocyanate with the hydroxyl group of the first or second polyol.

[0116] Furthermore, the polyisocyanate may contain a urethane group and an allophanate group in one molecule. The allophanate group is formed by the reaction of a urethane group with an isocyanate group of a diisocyanate, or by the reaction of two isocyanate groups of a diisocyanate with one hydroxyl group of the first or second polyol.

[0117] Furthermore, polyisocyanates may have other functional groups in a single molecule, such as isocyanurate groups and uretdione groups, in addition to urethane groups.

[0118] Alternatively, the polyisocyanate composition of this embodiment may further include, in addition to the polyisocyanate having a urethane group, a polyisocyanate having a urethane group and an allophanate group in its molecule, or a polyisocyanate having other functional groups such as an allophanate group, an isocyanurate group, or a uretdione group, either individually or in combination of two or more.

[0119] In the polyisocyanate composition of this embodiment, the ratio of the molar amount of uretdione groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is preferably 0 mol% to 20 mol%, more preferably 0.3 mol% to 20 mol%, even more preferably 1 mol% to 10 mol%, and particularly preferably 2 mol% to 10 mol%. By having a molar ratio of uretdione groups above the above lower limit, crystallization of the polyisocyanate composition can be further suppressed, and the polyisocyanate composition of this embodiment can be incorporated into paint compositions, especially polyaspartic paint compositions, as a uniform curing agent. This results in a coating film with excellent curability and surface appearance. Furthermore, the viscosity of the polyisocyanate composition becomes lower, allowing it to be made into a high-solids paint. On the other hand, by having a molar ratio of uretdione groups below the above upper limit, the low-temperature elongation of the coating film can be improved.

[0120] In the polyisocyanate composition of this embodiment, the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is preferably 0.01 mol% to 20.00 mol%, more preferably 0.01 mol% to 10.00 mol%, even more preferably 0.01 mol% to 5.00 mol%, and particularly preferably 0.01 mol% to 3.00 mol%. By keeping the molar ratio of isocyanurate groups below the above upper limit, the low-temperature elongation of the coating film can be improved. On the other hand, the lower the molar amount of isocyanurate groups, the better the low-temperature elongation of the coating film can be.

[0121] The molar amounts of each functional group in a polyisocyanate composition are, for example, 13 The molar amounts of the specific functional groups can be measured by 13C-NMR spectroscopy, and the molar proportion of each functional group can be calculated using the calculated molar amounts of each functional group. Specifically, it can be calculated using the method described in the examples below.

[0122] [Diisocyanate] Diisocyanates are at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

[0123] Examples of aliphatic diisocyanates include, but are not limited to, 1,4-diisocyanatobutane, 1,5-diisocyanatopentane (hereinafter sometimes abbreviated as "PDI"), ethyl(2,6-diisocyanato)hexanoate, 1,6-diisocyanatohexane (hereinafter sometimes abbreviated as "HDI"), 1,9-diisocyanatononane, 1,12-diisocyanatododecane, and 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane. These aliphatic diisocyanates may be used individually or in combination of two or more.

[0124] Examples of alicyclic diisocyanates include, but are not limited to, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane (hereinafter sometimes abbreviated as "hydrogenated XDI"), 1,3- or 1,4-diisocyanatocyclohexane, 3,5,5-trimethyl1-isocyanato-3-(isocyanatomethyl)cyclohexane (hereinafter sometimes abbreviated as "IPDI"), 4-4'-diisocyanato-dicyclohexylmethane (hereinafter sometimes abbreviated as "hydrogenated MDI"), and 2,5- or 2,6-diisocyanatomethylnorbornane. These alicyclic diisocyanates may be used individually or in combination of two or more.

[0125] These aliphatic diisocyanates and alicyclic diisocyanates may be used individually, or two or more aliphatic diisocyanates and alicyclic diisocyanates may be used in combination.

[0126] Among these, PDI, HDI, IPDI, hydrogenated XDI, or hydrogenated MDI are preferred as diisocyanates, PDI, HDI, or IPDI are more preferred, and HDI is even more preferred.

[0127] In addition to the diisocyanate described above, isocyanate monomers such as those shown below may also be used in the production of polyisocyanates. (1) Aromatic diisocyanates such as diphenylmethane-4,4'-diisocyanate (MDI), 1,5-naphthalene diisocyanate, tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and m-tetramethylxylylene diisocyanate (TMXDI). (2) Triisocyanates such as 4-isocyanate methyl-1,8-octamethylene diisocyanate (hereinafter sometimes referred to as "NTI"), 1,3,6-hexamethylene triisocyanate (hereinafter sometimes referred to as "HTI"), bis(2-isocyanatoethyl)2-isocyanatoglutarate (hereinafter sometimes referred to as "GTI"), and lysine triisocyanate (hereinafter sometimes referred to as "LTI").

[0128] [First polyol] The number-average molecular weight of the polyol is 200 to 2000, preferably 300 to 1500, more preferably 350 to 1200, and even more preferably 400 to 1000. Having a number-average molecular weight of the polyol above the lower limit results in a coating film with high and good elongation at low temperatures of around -20°C. On the other hand, having a number-average molecular weight of the polyol below the upper limit allows the viscosity of the polyisocyanate composition to be kept low, enabling the production of a high-solids coating.

[0129] The number-average molecular weight (Mn) of a polyol is, for example, the number-average molecular weight of polystyrene measured by GPC. Furthermore, when two or more polyols are used in mixture, the number-average molecular weight of the mixture is calculated.

[0130] The viscosity of the polyol at 25°C is preferably 90 mPa·s to 3000 mPa·s, more preferably 100 mPa·s to 2500 mPa·s, and even more preferably 100 mPa·s to 2000 mPa·s. A viscosity of the polyol above the lower limit results in greater and better elongation at low temperatures of around -20°C when applied as a coating film. On the other hand, a viscosity of the polyol below the upper limit allows for a lower viscosity of the polyisocyanate composition, enabling the production of a high-solids coating.

[0131] The viscosity of the polyol at 25°C can be measured by the method described in the examples below.

[0132] The average number of hydroxyl groups in a polyol is 2 or 3.

[0133] By using a polyol with an average number of hydroxyl groups of 2, the viscosity of the polyisocyanate composition can be reduced, resulting in a high-solids coating. Furthermore, because the polyisocyanate has fewer branches, the elongation at low temperatures of around -20°C when applied as a coating film is greater, resulting in a superior coating.

[0134] Furthermore, by using a polyol with an average number of hydroxyl groups of 3, crystallization can be further suppressed, and the polyisocyanate composition of this embodiment can be incorporated into paint compositions, particularly polyaspartic paint compositions, as a uniform curing agent. This results in a coating film with superior curability and surface appearance.

[0135] The polyol is at least one selected from the group consisting of polyester polyols and polyoxyalkylene polyols.

[0136] (Polyester polyol) The number-average molecular weight of the polyesterol can be between 200 and 2000, preferably between 300 and 1500, more preferably between 350 and 1200, and even more preferably between 400 and 1000.

[0137] Examples of polyester polyols include either (1) or (2) below. (1) A polyester polyol obtained by a condensation reaction of a dibasic acid alone or a mixture of two or more dibasic acids with a dihydric or higher alcohol alone or a mixture of two or more dihydric alcohols. (2) Polycaprolactone polyol obtained by ring-opening polymerization of ε-caprolactone with a divalent or higher alcohol.

[0138] Examples of the aforementioned dibasic acids include succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic anhydride, maleic acid, phthalic acid, glutaric acid, speric acid, azelaic acid, sebacic acid, decandioic acid, itaconic acid, itaconic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, tetrahydrophthalic acid, tetrahydrophthalic anhydride, and other carboxylic acids.

[0139] Examples of the aforementioned alcohols with a valency of 2 or higher include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, 2-ethyl-1,3-hexanediol, trimethylolpropane, glycerin, pentaerythritol, 2-methylolpropanediol, ethoxylated trimethylolpropane, 1,3-propanediol, pentane-1,5-diol, heptane-1,7-diol, octane-1,8-diol, nonane-1,9-diol, decane-1,1 Examples include 0-diol, dodecane-1,12-diol, cyclohexane-1,4-dimethanol, 4,4'-(1-methylethylidene)biscyclohexanol, 1,1,1-trimethylolethane, hexane-1,2,6-triol, dipropylene glycol, propane-1,2-diol, butane-1,3-diol, hexane-1,2-diol, 2-methylpentane-2,4-diol, 3-methylpentane-1,5-diol, octane-1,2-diol, 2-butyl-2-ethylpropane-1,3-diol, decane-1,2-diol, and 2-methyl-1,3-propanediol.

[0140] Among these, bifunctional or trifunctional polycaprolactone polyols are preferred as polyester polyols.

[0141] Examples of commercially available bifunctional polycaprolactone polyols include Daicel's product names "Praxel 210" (number average molecular weight 1000), "Praxel 210CP" (number average molecular weight 1000), "Praxel 212" (number average molecular weight 1250), "Praxel 212CP" (number average molecular weight 1250), "Praxel 220" (number average molecular weight 2000), "Praxel 220CPB" (number average molecular weight 2000), and "Praxel 220 Examples include "CPT" (number average molecular weight 2000), Ingevity's product names "Capa2043" (number average molecular weight 400, viscosity at 25°C 246 mPa·s), "Capa2054" (number average molecular weight 550, viscosity at 25°C 360 mPa·s), "Capa2085" (number average molecular weight 830, viscosity at 25°C 627 mPa·s), and "Capa2067A" (number average molecular weight 650, viscosity at 25°C 493 mPa·s).

[0142] In addition, commercially available bifunctional polyester polyols such as "Kuraray Polyol P-510" (number average molecular weight 500, viscosity at 25°C 540 mPa·s) manufactured by Kuraray Co., Ltd., and "ODX2406" (number average molecular weight 440, viscosity at 25°C 460 mPa·s) manufactured by DIC Corporation may be used.

[0143] Examples of commercially available trifunctional polycaprolactone polyols include Daicel's "Praxel 305" (number average molecular weight 550), "Praxel 308" (number average molecular weight 850), "Praxel 309" (number average molecular weight 900), "Praxel 312" (number average molecular weight 1250), and "Praxel 320" (number average molecular weight 2000); DIC's "ODX2542C" (number average molecular weight 850); and Ingevity's "Capa3050" (number average molecular weight 540, viscosity at 60°C 160 mPa·s) and "Capa23091" (number average molecular weight 900, viscosity at 60°C 165 mPa·s).

[0144] (Polyoxyalkylene polyol) Polyoxyalkylene polyols are -O(CH2)n This polyol contains repeating units represented by - and is divalent to tetravalent, and can be derived from a divalent to tetravalent alcohol and ethylene oxide, propylene oxide, tetrahydrofuran, etc. Furthermore, although not particularly limited, it can be obtained by cationic polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc., using a divalent to tetravalent alcohol as an initiator in the presence of a catalyst.

[0145] The number-average molecular weight of the polyoxyalkylene polyol is preferably 200 to 2000, more preferably 200 to 1500, and even more preferably 200 to 1000.

[0146] As initiators, dihydric alcohols include: ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,3-butylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, pentaerythritol, 2-methylolpropanediol, 2-ethyl-1,3-hexanediol, 1,3-propanediol, pentane-1,5-diol, heptane-1,7-diol, octane-1,8-diol, nonane-1,9-diol, decane-1,10-diol, dodecane-1,12-diol, and cyclohexane-1,4-dimethyl Examples of polyisocyanate components that can be used include: 4,4'-(1-methylethylidene)biscyclohexanol, 1,1,1-trimethylolethane, hexane-1,2,6-triol, dipropylene glycol, propane-1,2-diol, butane-1,3-diol, hexane-1,2-diol, 2-methylpentane-2,4-diol, 3-methylpentane-1,5-diol, octane-1,2-diol, 2-butyl-2-ethylpropane-1,3-diol, decane-1,2-diol, 2-methyl-1,3-propanediol, etc. Trihydric alcohols such as glycerin and trimethylolpropane, and tetrahydric alcohols such as pentaerythritol. From the viewpoint of obtaining a low-viscosity polyisocyanate component, branched polyhydric alcohols are preferred.

[0147] As catalysts, hydroxides such as lithium, sodium, and potassium, or strongly basic catalysts such as alkoxides and alkylamines can be used.

[0148] Cationic polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, etc. is preferably carried out in a nitrogen gas atmosphere, with the ethylene oxide, propylene oxide, tetrahydrofuran, etc. and the above-mentioned initiator set in a molar ratio to achieve a predetermined molecular weight, and then 0.1 ppm to 100 ppm of catalyst added to the ethylene oxide, propylene oxide, tetrahydrofuran, etc., and reacted at a temperature of 150°C to 200°C for 4 to 10 hours.

[0149] Examples of commercially available bifunctional polyoxyalkylene polyols include "ECOTRION H1000" (number average molecular weight 1000, viscosity at 25°C 489 mPa·s) and "ECOTRION H2000" (number average molecular weight 2000, viscosity at 25°C 1701 mPa·s) from SK Chemicals; "Velvet H250" (number average molecular weight 227, viscosity at 25°C 107 mPa·s) from Allessa; and "BioPTMG650" (number average molecular weight 655, viscosity at 25°C 351 mPa·s) from Mitsubishi Chemical Corporation.

[0150] The polyol preferably comprises two polyester polyols with different structures, or a polyester polyol and a polyoxyalkylene polyol. By including the above combination of two polyols, crystallization can be further suppressed.

[0151] Furthermore, when using two polyester polyols with different structures, or a combination of a polyester polyol and a polyoxyalkylene polyol, the blending ratio can be adjusted as appropriate so that the number average molecular weight falls within the above range. These polyester polyols can be blended in mass ratios such as 3:1 to 1:3, 2:1 to 1:2, and 1.5:1 to 1:1.5.

[0152] The polyoxyalkylene polyol content is preferably 30% by mass or less, more preferably 28% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less, based on the total mass of the first polyol and the second polyol. By keeping the polyoxyalkylene polyol content below the above upper limit, the weather resistance of the resulting coating film can be improved. The lower limit of the polyoxyalkylene polyol content is not particularly limited and can be, for example, 0%, 1%, 2%, 3%, etc.

[0153] When using a combination of a polyol with an average number of hydroxyl groups of 2 and a polyol with an average number of hydroxyl groups of 3, it is preferable that the polyol with an average number of hydroxyl groups of 2 is present in greater proportion than the polyol with an average number of hydroxyl groups of 3. Specifically, the content of the polyol with an average number of hydroxyl groups of 3 is preferably 30% by mass or less, more preferably 28% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less, based on the total mass of the first polyol and the second polyol. By keeping the content of the polyol with an average number of hydroxyl groups of 3 below the above upper limit, the elongation at low temperatures of around -20°C when used as a coating film can be improved. The lower limit of the content of the polyol with an average number of hydroxyl groups of 3 is not particularly limited and can be, for example, 0%, 1%, 2%, 3%, etc.

[0154] [Second polyol] In the polyisocyanate composition of this embodiment, by using a second polyol in addition to the first polyol, turbidity is almost eliminated and crystallization is suppressed. The polyisocyanate composition of this embodiment can be incorporated into paint compositions, particularly polyaspartic paint compositions, as a uniform curing agent. This results in a coating film with excellent curability and surface appearance.

[0155] The second polyol is a monool, diol, or triol having a branched chain with 2 to 20 carbon atoms.

[0156] Monoalcohols may contain one or more groups selected from the group consisting of ether groups, ester groups, carbonyl groups, and phenyl groups in their molecule. For example, benzyl alcohol may be used, but monoalcohols consisting only of saturated hydrocarbon groups are preferred. Furthermore, branched monoalcohols are more preferred. Examples of such monoalcohols include 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 3,3,5-trimethyl-1-hexanol, tridecanol, pentadecanol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, and trimethylcyclohexanol.

[0157] Examples of diols include ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, neopentyl glycol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-denodiol. Examples include linear aliphatic diols such as candiol, diethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; and branched aliphatic diols such as 2-ethyl-1,3-hexanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, and 2,2-diethyl-1,3-propanediol. These may be used individually or in combination of two or more. Among these, branched aliphatic diols are preferred because they can more effectively suppress crystallization.

[0158] Examples of trialcohols include glycerin and trimethylolpropane.

[0159] In particular, the second polyol is preferably a diol having a branched chain with 3 to 20 carbon atoms. By using a diol having a branched chain with 3 to 20 carbon atoms, crystallization can be further suppressed.

[0160] The content of the second polyol can be 35% by mass or less, preferably 1% to 30% by mass, more preferably 5% to 20% by mass, even more preferably 5% to 15% by mass, and particularly preferably 8% to 12% by mass, based on the total mass of the first polyol and the second polyol. When the content of the second polyol is above the lower limit, there is almost no turbidity, and the crystallinity can be maintained more well, allowing the polyisocyanate composition of this embodiment to be incorporated into paint compositions, especially polyaspartic paint compositions, as a more uniform curing agent. This results in a coating film with superior curability and surface appearance. On the other hand, when the content of the second polyol is below the upper limit, the viscosity can be made lower and more efficient. In addition, the elongation at low temperatures of around -20°C when used as a coating film can be made more efficient.

[0161] <Other ingredients> The polyisocyanate composition of this embodiment preferably contains one or more selected from the group consisting of ultraviolet absorbers and light stabilizers. Including ultraviolet absorbers and light stabilizers results in a coating film with superior weather resistance.

[0162] While not particularly limited, examples of UV absorbers include benzotriazole compounds, triazine compounds, benzophenone compounds, and cyanoacrylate compounds.

[0163] Benzotriazole compounds are not particularly limited, but examples include the trade names Tinuvin P·PS·99-2·213·234·326·329·360·384-2·571·900·928·970·1130 manufactured by BASF Japan Ltd.; Adeka Stab LA-24·29·31RG·31G·32·36·36RG·F70 manufactured by ADEKA Corporation; and EVERSORB 70·71·72·73·74·75·76·77·78·79·80·81·82·88·89·109·234 manufactured by Taiwan Yongguang Chemical Industry Co., Ltd.

[0164] Triazine compounds are not particularly limited, but examples include the trade names Tinuvin 400, 400-DW, 405, 460, 477, 479, 479-DW, 1577ED, and 1600 manufactured by BASF Japan Ltd., and EVERSORB 40, 41FD, and 45 manufactured by Taiwan Yongguang Chemical Industry Co., Ltd.

[0165] Benzophenone compounds are not particularly limited, but examples include Chimassorb 81·81FL and Uvinul 3049·3050 from BASF Japan Ltd.; Adeka Stab 1413 from ADEKA Corporation; and EVERSORB 10·11·12·51·52 from Taiwan Yongguang Chemical Industry Co., Ltd.

[0166] The cyanoacrylate compounds are not particularly limited, but examples include the trade names Uvinul 3030FF, 3035, and 3039 manufactured by BASF Japan Ltd.

[0167] From the viewpoint of maintaining the weather resistance of the coating film over a long period of time, benzotriazole compounds, triazine compounds, or benzophenone compounds are preferred, and benzotriazole compounds or triazine compounds are more preferred.

[0168] While not particularly limited, examples of light stabilizers include hindered amine compounds.

[0169] Hindered amine compounds are not particularly limited, but examples include the trade names Tinuvin 111FDL, 123, 123-DW, PA144, 152, 249, 292, 783FDL, and 765 manufactured by BASF Japan Ltd.; Adeka Stab LA-52, 57, 63P, 68, 72, 77Y, 77G, 81, and 402AF manufactured by ADEKA Corporation; and EVERSORB 60, 61, 90, 91FD, 93, 94FD, 95, 765, and S02 manufactured by Taiwan Yongguang Chemical Industry Co., Ltd.

[0170] UV absorbers and light stabilizers may be used individually or in combination of two or more types.

[0171] The total amount of UV absorber and light stabilizer added is preferably 10 ppm by mass or more and 15,000 ppm by mass or less, relative to the total mass of the polyisocyanate composition.

[0172] The polyisocyanate composition of this embodiment may further contain an antioxidant.

[0173] Examples of antioxidants include hindered phenol-based antioxidants.

[0174] Hindered phenol antioxidants are not particularly limited, but examples include dibutylhydroxytoluene (hereinafter sometimes abbreviated as "BHT"); BASF brand names "Irganox 1010", "Irganox 1135", "Irganox 1330", "Irganox 3114", "Irganox 565", and "Irganox 1520L"; and ADEKA Corporation brand names "ADEKA Stab AO-20", "ADEKA Stab AO-30", "ADEKA Stab AO-50", "ADEKA Stab AO-60", and "ADEKA Stab AO-80".

[0175] <Method for producing polyisocyanate composition> The polyisocyanate composition of this embodiment is obtained by simultaneously reacting an excess of diisocyanate with a first polyol and a second polyol, or by reacting an excess of diisocyanate with a first polyol and then with a second polyol, or by reacting an excess of diisocyanate with a second polyol and then with a first polyol, or by mixing a polyisocyanate obtained by reacting an excess of diisocyanate with a first polyol with a polyisocyanate obtained by reacting an excess of diisocyanate with a second polyol. Unreacted diisocyanate monomers may also be removed after each reaction is complete.

[0176] The reaction of excess diisocyanate with the first or second polyol is a known urethane formation reaction. Hereafter, the first and second polyols may be collectively referred to simply as polyols.

[0177] The urethane reaction can be carried out by mixing an excess of diisocyanate with a polyol and adding a urethane reaction catalyst as needed.

[0178] The urethane reaction catalyst is not particularly limited, but examples include tin-based compounds, zinc-based compounds, amine-based compounds, and the like.

[0179] The urethane reaction temperature is preferably 50°C to 160°C, and more preferably 60°C to 120°C.

[0180] By keeping the urethane reaction temperature below the above upper limit, discoloration of the polyisocyanate tends to be more effectively suppressed.

[0181] Furthermore, the urethane reaction time is preferably 30 minutes to 4 hours, more preferably 1 hour to 3 hours, and even more preferably 1 hour to 2 hours.

[0182] The ratio of the molar amount of isocyanate groups in the isocyanate monomer to the molar amount of hydroxyl groups in the alcohol (molar ratio of isocyanate groups to hydroxyl groups) is preferably between 2 / 1 and 50 / 1. A molar ratio above the lower limit allows for a lower viscosity polyisocyanate. A molar ratio below the upper limit allows for a higher yield of urethane group-containing polyisocyanate.

[0183] An allophanate reaction can be carried out after the urethane reaction described above. The allophanate reaction can be carried out by reacting an isocyanate group with the formed urethane group, or by reacting two isocyanate groups with one hydroxyl group. That is, the allophanate reaction may be carried out immediately after the urethane reaction, or the polyisocyanate obtained by the urethane reaction may be mixed with a polyisocyanate obtained by a separate allophanate reaction. The allophanate reaction may be carried out using an allophanate reaction catalyst.

[0184] The allophanate reaction catalyst is not limited to the following, but examples include alkyl carboxylates of tin, lead, zinc, bismuth, zirconium, zirconyl, etc.

[0185] Examples of alkyl carboxylates of tin (organotin compounds) include tin 2-ethylhexanoate and dibutyltin dilaurate.

[0186] Examples of alkyl carboxylates of lead (organic lead compounds) include lead 2-ethylhexanoate.

[0187] Examples of zinc alkyl carboxylates (organozinc compounds) include zinc 2-ethylhexanoate.

[0188] Examples of alkyl carboxylate salts of bismuth include bismuth 2-ethylhexanoate.

[0189] Examples of alkyl carboxylate salts of zirconium include zirconium 2-ethylhexanoate.

[0190] Examples of alkyl carboxylate salts of zirconyl include zirconyl 2-ethylhexanoate.

[0191] These catalysts can be used individually or in combination of two or more types.

[0192] The lower limit of the amount of allophanate reaction catalyst used is preferably 10 ppm by mass, more preferably 15 ppm by mass, even more preferably 18 ppm by mass, and particularly preferably 20 ppm by mass, relative to the mass of the charged isocyanate monomer.

[0193] The upper limit of the amount of allophanate reaction catalyst used as described above is preferably 1000 ppm by mass, more preferably 800 ppm by mass, even more preferably 500 ppm by mass, and particularly preferably 300 ppm by mass, relative to the mass of the charged isocyanate monomer.

[0194] In other words, the amount of allophanate reaction catalyst used is preferably 10 ppm to 1000 ppm by mass, more preferably 15 ppm to 800 ppm by mass, even more preferably 18 ppm to 500 ppm by mass, and particularly preferably 20 ppm to 300 ppm by mass, relative to the mass of the charged isocyanate monomer.

[0195] Furthermore, the lower limit of the allophanate reaction temperature is preferably 80°C, and more preferably 100°C.

[0196] Furthermore, the upper limit of the allophanate reaction temperature is preferably 200°C, and more preferably 180°C.

[0197] In other words, the allophanate reaction temperature is preferably 80°C to 200°C, and more preferably 100°C to 180°C.

[0198] By keeping the allophanate reaction temperature above the lower limit, the reaction rate can be further improved. By keeping the allophanate reaction temperature below the upper limit, discoloration of the polyisocyanate tends to be more effectively suppressed.

[0199] In the allophanate reaction, the molar ratio of allophanate groups to urethane groups (allophanate group / urethane group molar ratio) can be adjusted to the above range by confirming the increase in the refractive index of the reaction solution. The reaction is stopped when the refractive index of the reaction solution reaches the desired value.

[0200] <Properties of Polyisocyanate Compositions> The isocyanate group content of the polyisocyanate composition of this embodiment is preferably 5.0% by mass or more and 20.0% by mass or less, more preferably 7.0% by mass or more and 18.0% by mass or less, even more preferably 7.5% by mass or more and 15.0% by mass or less, particularly preferably 8.5% by mass or more and 15.0% by mass or less, and most preferably 10.0% by mass or more and 13.5% by mass or less. By having an isocyanate group content above the lower limit, the concentration of urea bonds that serve as bonding sites in the coating film can be increased, resulting in better weather resistance when applied as a coating film. On the other hand, by having an isocyanate group content below the upper limit, it is possible to suppress the concentration of urea bonds that serve as bonding sites in the coating film from rising too high, resulting in good elongation at low temperatures of around -20°C when applied as a coating film.

[0201] The isocyanate group content can be measured using the method described in the examples below.

[0202] The lower limit of the viscosity of the polyisocyanate composition of this embodiment at 25°C is preferably 100 mPa·s, more preferably 500 mPa·s, even more preferably 700 mPa·s, and particularly preferably 800 mPa·s. On the other hand, the upper limit of viscosity is preferably 3000 mPa·s, more preferably 2500 mPa·s, even more preferably 2000 mPa·s, and particularly preferably 1750 mPa·s.

[0203] In other words, the viscosity of the polyisocyanate composition of this embodiment at 25°C is preferably 100 mPa·s or more and 3000 mPa·s or less, more preferably 500 mPa·s or more and 2500 mPa·s or less, even more preferably 700 mPa·s or more and 2000 mPa·s or less, and particularly preferably 800 mPa·s or more and 1750 mPa·s or less.

[0204] When the viscosity is above the lower limit mentioned above, it tends to be possible to better maintain workability during paint compounding. On the other hand, when the viscosity is below the upper limit mentioned above, the amount of solvent used when preparing the polyaspartic paint composition can be further reduced.

[0205] Viscosity can be measured by the method described in the examples below.

[0206] ≪Polyaspalatic paint composition≫ The polyaspartic coating composition of this embodiment comprises the polyisocyanate composition of Embodiment 1 or Embodiment 2 described above, and an aspartic acid ester compound.

[0207] Aspartate ester compounds are compounds represented by the following general formula (I).

[0208] [ka]

[0209] In general formula (I), X11 is an n-valent organic group obtained by removing the primary amino groups of an n11-valent polyamine. R 11 and R 12 are the same or different organic groups that are inert to isocyanate groups under the reaction conditions. n11 is an integer of 2 or more.

[0210] X in formula (I) 11 is not particularly limited, but from the viewpoint of light fastness, it is preferably an organic group based on an aliphatic and / or alicyclic polyamine having no aromatic group. For example, an n11-valent polyamine selected from the following group: ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 2,5-diamino-2,5-dimethylhexane, 2,2,4- and / or 2,4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane, 1,12-diaminododecane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 2,4- and / or 2,6-hexahydrotoluenediamine, 2,4'- and / or 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 2,4,4'-triamino-5-methyldicyclohexylmethane, and an organic group based on a polyether polyamine having a number average molecular weight of 148 or more and 6000 or less and a primary amino group bonded to an aliphatic group.

[0211] Among them, X 11 is preferably an organic group based on 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 2,2,4- and / or 2,4,4-trimethyl-1,6-diaminohexane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 4,4'-diaminodicyclohexylmethane, or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane. More preferably, it is an organic group based on 4,4'-diaminodicyclohexylmethane or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

[0212] R in equation (I) 11 and R 12 The phrase "inert to isocyanate groups under reaction conditions" means that these groups do not contain tserevich-active hydrogen-containing groups (CH acidic compounds) such as hydroxyl groups, amino groups, or thiol groups.

[0213] R 11 and R 12 These are preferably alkyl groups having 1 to 10 carbon atoms, and more preferably methyl, ethyl, or butyl groups, independently of each other.

[0214] In equation (I), n11 is preferably an integer between 2 and 6, more preferably an integer between 2 and 4, and even more preferably 2.

[0215] Preferred aspartic acid ester compounds include, for example, aspartic acid ester compounds derived from two molecules of aspartic acid having a secondary amino group and one molecule of 4,4'-diaminodicyclohexylmethane.

[0216] Commercially available aspartic acid ester compounds may be used. Examples of commercially available aspartic acid ester compounds include Evonik's "Amicure IC-221" (amine value 188 mg KOH / g resin, viscosity 450 mPa·s (typical value measured at 25°C)), "Amicure IC-321" (amine value 190 mg KOH / g resin, viscosity 450 mPa·s (typical value measured at 25°C)), "Amicure IC-322" (amine value 189 mg KOH / g resin, viscosity 150 mPa·s (typical value measured at 25°C)); and Feiyang's "Feispartic F420" (amine value 201 mg KOH / g resin, viscosity 1450 mPa·s (typical value measured at 25°C)), "Feispartic F520" (amine value 189 mg KOH / g resin, viscosity 1400 mPa·s (typical value measured at 25°C)).

[0217] The aspartic acid ester compounds described above may be used individually or in combination of two or more.

[0218] The method for producing aspartic acid ester compounds is not particularly limited, but for example, they can be produced by the reaction of a primary polyamine represented by the following formula (II) with a maleic acid ester or fumaric acid ester represented by the following formula (III).

[0219] X 11 -[NH2] n11 (II) R 11 OOC-CH=CH-COOR 12 (III)

[0220] (In the above formula, X 11 , R 11 , R 12 n11 is equivalent to what is expressed in equation (I).

[0221] Suitable polyamines are not particularly limited, but for example, X 11 The diamines mentioned above form the basis of this.

[0222] Furthermore, while there are no particular limitations on suitable maleic acid esters or fumaric acid esters, for example, R in formula (I) 11 and R 12 The group defined in R 11 and R 12 It is a maleate ester or fumarate ester having as such. Among them, R 11 and R 12 Maleic acid esters or fumarate esters in which the alkyl group has 1 to 10 carbon atoms are preferred, and dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, or dibutyl fumarate are more preferred.

[0223] The preparation of aspartate ester compounds from the described starting materials is preferably carried out in a temperature range of 0°C to 100°C. The starting materials are used in such proportions that each primary amino group contains at least one, preferably only one, olefin double bond. If desired, excess starting materials can be removed after the reaction by distillation. The reaction can be carried out in bulk or in the presence of a suitable solvent (not particularly limited, but for example, methanol, ethanol, propanol, or dioxane, or a mixture of such solvents).

[0224] <Isocyanate group / amino group> The molar ratio of isocyanate groups in a polyisocyanate composition to amino groups in an aspartic acid ester compound (isocyanate groups / amino groups) is preferably 1 / 10 or more and 10 / 1 or less, more preferably 1 / 5 or more and 5 / 1 or less, and even more preferably 1 / 2 or more and 2 / 1 or less.

[0225] By ensuring that the isocyanate group / amino group ratio is above the lower limit, the main component is not excessively present, resulting in good elongation of the coating film at low temperatures of around -20°C. Furthermore, by keeping the isocyanate group / amino group ratio within the above numerical range, a good balance between isocyanate and amino groups is maintained, allowing for a higher concentration of urea bonds, which serve as bonding sites in the coating film, thus improving the weather resistance of the coating film.

[0226] <Other ingredients> The polyaspartic coating composition of this embodiment may further contain, if necessary, other main components such as polyol-containing polyvalent active hydrogen compounds, melamine resin, epoxy resin, polyurethane resin, etc.

[0227] Furthermore, if the polyol described above has a carboxyl group, oxazoline group-containing compounds and carbodiimide group-containing compounds can be added. Also, if the polyol described above has a carbonyl group, hydrazide group-containing compounds and semicarbazide group-containing compounds can be added. These compounds may be added individually or in combination of two or more.

[0228] The polyaspartic coating composition of this embodiment preferably further contains a surface modifier as an additive, as it exhibits superior appearance when formed into a coating film. The type of surface modifier is not particularly limited and examples include silicone-based and acrylic-based agents.

[0229] The content of the surface modifier is preferably 0.05% by mass or more and 5% by mass or less relative to the resin content of the polyaspartic coating composition. A surface modifier content above the lower limit can further improve the appearance of the coating film. On the other hand, a surface modifier content below the upper limit results in better resistance to paint repellency, recoating properties, and stain resistance of the coating film.

[0230] Commercially available silicone-based surface modifiers can be used, such as BYK-300, BYK-302, BYK-306, BYK-307, BYK-310, BYK-313, BYK-315N, BYK-320, BYK-322, BYK-323, BYK-325, BYK-326, BYK-330, BYK-331, BYK-333, BYK-342, BYK-370, BYK-375, BYK-377, BYK-378, BYK-3760 (manufactured by BYK); Disparon 1711EF, Disparon 1761, Disparon LS-001, Disparon LS-050, Disparon LS-280, Disparon LS-460, Disparon LS-480 (manufactured by Kusumoto Kasei Co., Ltd.); Tego Flow Examples include Tego Glide 425, Tego Glide 100, Tego Glide 110, Tego Glide 130, Tego Glide 406, Tego Glide 420, Tego Glide 432, Tego Glide 435, Tego Glide 440, Tego Glide 450, Tego Glide 482, Tego Glide 485, Tego Glide ZG400, Tego wet KL245, Tego wet 250, Tego wet 260, Tego wet 265, Tego wet 270, and Tego wet 280 (manufactured by Evonik Tego Chemie). These can be used individually or in combination of two or more types.

[0231] As acrylic surface modifiers, commercially available products can be used, such as BYK-350, BYK-354, BYK-355, BYK-356, BYK-358N, BYK-361N, BYK-392, BYK-394, BYK-3441 (manufactured by BYK); Disparon LF-1983, Disparon LF-1984, LF-1985, Disparon UVX-35, Disparon UVX-36 (manufactured by Kusumoto Chemical Co., Ltd.); Tego Flow 300, Tego Flow 370, Tego Flow ATF2, Tego Flow ZFS460 (manufactured by Evonik Tego Chemie). These may be used individually or in combination of two or more.

[0232] Other types of surface modifiers not listed above can be commercially available, such as BYK-399, BYK-3440, BYK-3550, BYK-3560, BYK-3565, BYK-SILCLEAN 3700, BYK-SILCLEAN 3701, BYKETOL-OK (manufactured by BYK); Disparon UVX-272, Disparon UVX-2285, Disparon LHP-810, Disparon NSH-8430HF, Disparon LHP-90, Disparon LHP-91, Disparon LHP-95, Disparon LHP-96 (manufactured by Kusumoto Kasei Co., Ltd.). These may be used individually or in combination of two or more types.

[0233] The polyaspartic coating composition of this embodiment preferably further contains an antifoaming, anti-foaming, or defoaming agent as an additive, as it exhibits superior appearance when formed into a coating film. The type of antifoaming, anti-foaming, or defoaming agent is not particularly limited and examples include silicone-based and polymer-based agents.

[0234] The content of the defoaming, foam-suppressing, and defoaming agent is preferably 0.05% by mass or more and 5% by mass or less relative to the resin content of the polyaspartic coating composition. A content of the defoaming, foam-suppressing, and defoaming agent above the lower limit improves workability during compounding and stirring, and also improves the appearance of the resulting coating film. On the other hand, a content of the defoaming, foam-suppressing, and defoaming agent below the upper limit results in better paint repellency, recoatability, and stain resistance of the resulting coating film.

[0235] Commercially available silicone-based defoaming, anti-foaming, and defoaming agents can be used, such as BYK-063, BYK-065, BYK-066N, BYK-067A, BYK-077, BYK-081, BYK-1799 (manufactured by BYK); Disparon 1930N, Disparon 1934, Disparon SPX-44 (manufactured by Kusumoto Kasei Co., Ltd.); Tego Airex 900, Tego Airex 916, Tego Airex 931, Tego Airex 935, Tego Airex 962, Tego Airex 980, Tego Foamex N (manufactured by Evonik Tego Chemie). These may be used individually or in combination of two or more.

[0236] As polymer-based defoaming, anti-foaming, and defoaming agents, commercially available products can be used, for example, BYK-051N, BYK-052N, BYK-054, BYK-055, BYK-057, BYK-354, BYK-392, BYK-1752, BYK-1788, BYK-1790, BYK-1791, BYK-1794 (manufactured by BYK); Disparon OX-60, Disparon OX-6140, Disparon OX-70, Disparon OX-710, Disparon OX-750HF, Disparon OX-77EF, Disparon OX-880EF, Disparon O Examples include X-881, Disparon OX-883HF, Disparon LAP-10, Disparon LAP-20, Disparon LAP-30, Disparon 1952, Disparon 1958, Disparon 1960, Disparon P-410EF, Disparon PD-7, Disparon P-420, Disparon P-450, Disparon OX-881, Disparon OX-883HF, Disparon LAP-10, Disparon P-425, Disparon UVX-188, Disparon UVX-189, Disparon UVX-190 (manufactured by Kusumoto Kasei Co., Ltd.); Tego Airex 910, Tego Airex 920, Tego Airex 936, Tego Airex 944, Tego Airex 955 (manufactured by Evonik Tego Chemie). These can be used individually or in combination of two or more types.

[0237] Other types of defoaming, anti-foaming, and defoaming agents not listed above can be commercially available, such as BYK-088, BYK-141 (manufactured by BYK); Disparon OX-66EF, Disparon OX-715 (manufactured by Kusumoto Chemical Co., Ltd.); Tego Airex 940, Tego Airex 945, Tego Airex 950, Tego Airex 986 (manufactured by Evonik Tego Chemie). These may be used individually or in combination of two or more types.

[0238] The polyaspartic coating composition of this embodiment may further contain one or more selected from the group consisting of ultraviolet absorbers and light stabilizers as described above.

[0239] The polyasparatic coating composition of this embodiment may further contain molecular sieves. Molecular sieves are natural or synthetic zeolites having a relatively high internal surface area and uniform pore size. Molecular sieves have relatively high adsorption capacity. Therefore, molecular sieves are used, in particular, as adsorbents, for example, as water absorbents.

[0240] Suitable molecular sieves have a pore diameter of 2.0 angstroms to 10 angstroms, preferably 2.5 angstroms to 4.0 angstroms, and more preferably about 3.0 angstroms.

[0241] The polyaspartic coating composition of this embodiment generally contains 0.1% to 15% by mass, preferably 0.5% to 8% by mass, of molecular sieves based on the total mass.

[0242] The polyaspartic coating composition of this embodiment may further contain a matting agent. The matting agent is not particularly limited, but examples include dry silica and precipitated silica.

[0243] Dry silica is not particularly limited, but examples include the product names "ACEMATT 3400," "ACEMATT3300," and "ACEMATT TS100" manufactured by Evonik Japan Co., Ltd.

[0244] While there are no particular limitations on the type of settling silica, examples include the product names "ACEMATT 3600", "ACEMATT OK607(LC)", "ACEMATT OK390", "ACEMATT OK900", "ACEMATT OK520", "ACEMATT OK500", "ACEMATT OK412", "ACEMATT HK390", "ACEMATT 790", "ACEMATT 82", "ACEMATT HK520", "ACEMATT HK400", "ACEMATT 810", "ACEMATT HK125", and "ACEMATT HK440" manufactured by Evonik Japan Co., Ltd.

[0245] The matting agent may be surface-treated or untreated. Among these, the use of dry silica is particularly preferred.

[0246] Generally, a matting agent is added in an amount of 3% to 20% by mass, based on the total mass of the polyaspartic coating composition of this embodiment.

[0247] The polyaspartic coating composition of this embodiment may further contain a dispersant. Commercially available dispersants can be used, such as "DESPERBYK-103," "DESPERBYK-145," "DESPERBYK-2155," and "DESPERBYK-2159" manufactured by BYK. These may be used individually or in combination of two or more.

[0248] The polyaspartic coating composition of this embodiment generally contains 0.1% to 15% by mass, preferably 0.3% to 8% by mass, of the total mass of the dispersant.

[0249] The polyaspartic coating composition of this embodiment may further contain, as other components, pigments such as titanium dioxide, carbon black, indigo, quinacridone, and pearl mica; metal powder pigments such as aluminum; rheology control agents such as hydroxyethylcellulose, urea compounds, and microgels; surface modifiers; and curing accelerators such as tin compounds, zinc compounds, and amine compounds.

[0250] <Method for producing polyasparatic coating composition> The polyaspartic coating composition of this embodiment is obtained by mixing the above-mentioned aspartic acid ester compound with other components as needed to obtain a mixture, and then blending the above-mentioned polyisocyanate composition, which is a curing agent component, into the mixture and mixing using a known method. At this time, a solvent may or may not be used. Since the polyaspartic coating composition of this embodiment has a lower viscosity than conventional ones, it can be manufactured while maintaining workability even in a high-solid formulation.

[0251] <Application> The polyasparatic coating composition of this embodiment is suitably used as a primer, intermediate coat, or topcoat on metals such as steel plates and surface-treated steel plates, plastics, inorganic materials such as ceramics, glass, and concrete, by methods such as roll coating, curtain flow coating, spray coating, electrostatic coating, bell coating, dipping, roller coating, and brush coating.

[0252] The polyasparatic coating composition of this embodiment is suitably used to impart aesthetic properties, weather resistance, acid resistance, rust prevention, chipping resistance, adhesion, etc., to pre-coated metals including rust-resistant steel plates, automotive painted parts, plastic painted parts, etc.

[0253] Furthermore, the polyaspartic coating composition of this embodiment is also useful as an adhesive, a sealant, an elastomer, a foam, a surface treatment agent, and the like.

[0254] In addition, the polyaspartic coating composition of the present embodiment has a softened coating film, an increased crosslink density of the coating film, and particularly excellent weather resistance. Therefore, the polyaspartic coating composition of the present embodiment is suitably used for the heavy anti-corrosion coating of structures that require long-term weather resistance, such as bridges, highways, transmission towers, and wind power generation facilities (towers, blades, etc.) that are exposed to harsh environments such as wind, rain, snow, and temperature differences.

[0255] ≪Coating film≫ The coating film of the present embodiment is formed by curing the above-described polyaspartic coating composition.

[0256] The coating film of the present embodiment is excellent in weather resistance and elongation at a low temperature of about -20°C.

[0257] The coating film of the present embodiment is obtained by applying the above-described polyaspartic coating composition using a known method such as roll coating, curtain flow coating, spray coating, bell coating, or electrostatic coating, and then curing it through a normal temperature drying or baking process.

Examples

[0258] Hereinafter, the present embodiment will be described in more detail by way of examples, but the present embodiment is not limited to these examples.

[0259] The measurement methods for various physical properties and the methods for various evaluations will be described below. Unless otherwise specified, "parts" and "%" mean "parts by mass" and "mass%".

[0260] <Measurement method of physical properties> [Physical property 1] (NCO content (mass%)) The NCO content (isocyanate content, mass %) of the polyisocyanate composition was measured as follows. After accurately weighing 1 g or more and 3 g or less of the polyisocyanate composition produced in the production example into an Erlenmeyer flask (W g), 20 mL of toluene was added to completely dissolve the polyisocyanate composition. Then, 10 mL of a toluene solution of 2N di-n-butylamine was added, and after complete mixing, it was left at room temperature for 15 minutes. Further, 70 mL of isopropyl alcohol was added to this solution and mixed completely. This solution was titrated with a 1N hydrochloric acid solution (factor F) using an indicator to obtain a titration value of V2 mL. The same titration operation was carried out without using polyisocyanate to obtain a titration value of V1 mL. From the obtained titration values V2 mL and V1 mL, the NCO content rate (mass %) of the polyisocyanate was calculated based on the following formula.

[0261] (NCO content rate (mass %)) = (V1 - V2) × F × 42 / (W × 1000) × 100

[0262] [Physical property 2] (Molar ratio of each functional group) For the obtained polyisocyanate composition, C-NMR measurement was performed using Biospin Avance600 (trade name) manufactured by Bruker. 13 Specific measurement conditions were as follows.

[0263] (Measurement conditions). 13 C-NMR apparatus: AVANCE600 (manufactured by Bruker). CryoProbe (manufactured by Bruker). CryoProbe (registered trademark). CPDUL. 600S3-C / H-D-05Z. Resonance frequency: 150 MHz. Concentration: 60 wt / vol%. Shift reference: CDCl3 (77 ppm). Number of integrations: 10000 times. Pulse program: zgpg30 (proton complete decoupling method, waiting time 2 sec) [[ID=

[0264] The molar ratios of isocyanurate, uretdione, allophanate, and urethane groups were determined by dividing the integral value of the following signals by the number of carbon atoms being measured. Then, the molar ratios B / A, C × 100 / (A + B + C + D) (mol%), and D × 100 / (A + B + C + D) (mol%) were calculated, where A is the number of moles of urethane groups, B is the number of moles of allophanate groups, C is the number of moles of isocyanurate groups, and D is the number of moles of uretdione groups.

[0265] Isocyanurate group: (Integral value around 148.6 ppm) ÷ 3 Uretidione group: (Integral value around 157.8 ppm) ÷ 2 Urethane group: (Integral value around 156.5 ppm) ÷ 1 Allophanate group: (integral value around 154 ppm) ÷ 1

[0266] <Evaluation Method> [Rating 1] (Viscosity of polyisocyanate composition (mPa·s)) The viscosity of the polyisocyanate composition was measured at 25°C using an E-type viscometer (product name: RE-85R, manufactured by Toki Sangyo Co., Ltd.). A standard rotor (1°34' × R24) was used for the measurement. The rotation speed was set as follows.

[0267] (Rotation speed) 100 r.pm (if less than 128 mPa·s) 50 r.pm (when the pressure is between 128 mPa·s and 256 mPa·s) 20 r.pm (when the pressure is between 256 mPa·s and 640 mPa·s) 10 r.pm (when the pressure is between 640 mPa·s and 1280 mPa·s) 5 r.pm (when the pressure is between 1280 mPa·s and 2560 mPa·s) 2.5 rpm (when pressure is between 2560 mPa·s and 5120 mPa·s)

[0268] (Evaluation Criteria) A: Below 1500 mPa·s B: Exceeding 1500 mPa·s and below 2000 mPa·s C: Exceeding 2000 mPa·s and below 3000 mPa·s D: Exceeding 3000 mPa·s

[0269] [Evaluation 2] (Crystallinity of the polyisocyanate composition) The turbidity of the polyisocyanate composition at room temperature (23°C) was measured as the transmittance (%) at 550 nm in UV measurement using JASCO V-650. The measured transmittance was evaluated according to the following evaluation criteria.

[0270] (Evaluation criteria) A: Transmittance at 550 nm is 90% or more B: Transmittance at 550 nm is 80% or more and less than 90% C: Transmittance at 550 nm is 70% or more and less than 80% D: Transmittance at 550 nm is less than 70%

[0271] [Manufacture of the polyaspartic paint composition] The aspartic acid ester compound "Feispartic F420" (manufactured by Feiyang Co., Ltd., amine value 201 mgKOH / resin g) and each polyisocyanate composition were blended so that NCO / NH = 1.1 (molar ratio), and adjusted with n-butyl acetate so that the paint solid content became 80% by mass to obtain a polyaspartic paint composition. For Examples 1-17, the polyaspartic paint composition was manufactured by the method described later.

[0272] [Evaluation 3] (Appearance of the paint film) The polyaspartic paint composition obtained by the above method was applied to a glass plate with an applicator so that the dry film thickness was 40 μm or more and 60 μm or less. After application, each paint film was obtained by curing for 7 days under the conditions of 23°C and 50 RH% humidity. The appearance of each paint film was evaluated according to the following evaluation criteria.

[0273] (Evaluation criteria) A: The surface is very smooth and shows no irregularities. B: The surface is smooth, but there are some small irregularities. C: The surface has a lot of unevenness and wrinkles.

[0274] [Rating 4] (Weather resistance of the coating) The polyaspalatic coating composition obtained by the above method was applied to a white board using an applicator to a dry film thickness of 40 μm to 60 μm. After application, the coating was cured for 7 days at 23°C and 50 RH% humidity to obtain each coating film. Subsequently, it was evaluated using a DUE-PANEL light-controlled weather meter FDP manufactured by Suga Test Instruments Co., Ltd. under the conditions of JIS K5600-7-8. The weather resistance of each coating film was evaluated according to the evaluation criteria shown below.

[0275] (Evaluation Criteria) A: The gloss retention rate at 60 degrees after 2500 hours of exposure is over 90%. B: Gloss retention rate at 60 degrees Celsius is 90% or higher after 2000 hours of exposure. C: Gloss retention rate at 60 degrees Celsius after 1500 hours of exposure is between 80% and 90%. D: Gloss retention rate at 60 degrees after 1500 hours of exposure is less than 80%.

[0276] [Rating 5] (Low-temperature elongation of the coating film) The polyaspartic coating composition obtained by the above method was applied to a polypropylene (PP) board using an applicator to a dry film thickness of 40 μm to 60 μm. After application, the coating was cured for 7 days at 23°C and 50 RH% humidity to obtain each coating film. The elongation of the coating films was measured at -20°C using a tensile testing machine (Orientec, RTE-1210) and a constant temperature chamber (Orientec, TLA-R3T-FW) at a tensile speed of 20 mm / min and a gripping distance of 20 mm. The low-temperature elongation of each coating film was evaluated according to the evaluation criteria shown below.

[0277] (Evaluation Criteria) A: Coating elongation is 300% or more B: Coating elongation is 200% or more but less than 300% C: Coating elongation is 150% or more but less than 200% D: Coating elongation is 0% or more and less than 150%

[0278] <Production of polyisocyanate compositions> [Example 1-1] (Production of polyisocyanate composition PA1-a1) The inside of a four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen. 450 g of HDI, 74 g of the polycaprolactone polyol Capa2043 (manufactured by Ingevity; hereafter sometimes referred to as "PCL1"), and 74 g of the polycaprolactone polyol Capa2085 (manufactured by Ingevity; hereafter sometimes referred to as "PCL2") were added, and the urethane reaction was carried out at 100°C for 2 hours under stirring. After raising the temperature to 130°C, 0.11 g of a 2-ethyl-1-hexanol solution containing 20% ​​by mass of zirconyl 2-ethylhexanoate was added as an allophanate catalyst. When the refractive index of the reaction solution increased to 0.00094, 1.0 g of a 2-ethyl-1-hexanol solution containing 10% by mass of pyrophosphate (manufactured by Taihei Chemical Industry, trade name "Phosphoric Acid (105%)" diluted with 2-ethyl-1-hexanol) was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under the following conditions: 1st pass at 150°C (0.2 Torr), 2nd pass at 150°C (0.2 Torr), and 3rd pass at 160°C (0.2 Torr). The obtained polyisocyanate composition was liquid with a viscosity of 1,630 mPa·s and an NCO content of 9.4% by mass. The molar ratio of allophanate groups to urethane groups was 10 / 90. The obtained polyisocyanate composition was designated PA1-a1.

[0279] [Examples 1-2] (Production of polyisocyanate composition PA1-a2) A four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 450g of HDI, 74g of PCL1, and 74g of PCL2 were charged. The urethane reaction was carried out at 100°C for 2 hours under stirring. After raising the temperature to 140°C, the allophanate reaction was carried out for 3 hours. After 3 hours, the temperature was lowered to room temperature to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under the conditions of 150°C (0.2 Torr) for the first pass, 150°C (0.2 Torr) for the second pass, and 160°C (0.2 Torr) for the third pass. The obtained polyisocyanate composition was liquid, and the molar ratio of allophanate groups to urethane groups was 10 / 90. The obtained polyisocyanate composition was designated PA1-a2.

[0280] [Examples 1-3] (Production of polyisocyanate composition PA1-a3) Polyisocyanate composition PA1-a3 was prepared using the same method as in Example 1-1, except that the types and amounts of raw materials were as shown in the table below, and the reaction was stopped when the refractive index of the reaction solution increased to 0.00032.

[0281] [Examples 1-4] (Production of polyisocyanate composition PA1-a4) Polyisocyanate composition PA1-a4 was produced using the same method as in Example 1-1, except that the types and amounts of raw materials were as shown in the table below, and the reaction was stopped when the refractive index of the reaction solution increased to 0.0028.

[0282] [Examples 1-6 to 1-13, and Examples 1-15, 1-18] (Production of polyisocyanate compositions PA1-a6 to PA1-a13 and PA1-a15, PA1-a17) Each polyisocyanate composition was prepared using the same method as in Example 1-1, except that the types and amounts of raw materials were as shown in the table below.

[0283] [Examples 1-5] (Production of polyisocyanate composition PA1-a5) A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. 100 parts by mass of HDI were added, and the reactor temperature was maintained at 60°C under stirring. 0.15 parts by mass of a solution of tetrabutylammonium acetate, the isocyanurate reaction catalyst, diluted to 10% by mass with 2-ethyl-1-hexanol, was added to carry out the isocyanurate reaction. When the NCO content of the reaction solution reached 43.8% by mass, phosphoric acid was added to stop the reaction. The reaction solution was then maintained at 90°C for 1 hour. After cooling, the reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator. An isocyanurate-type polyisocyanate with an NCO content of 23.1% by mass and a viscosity of 1350 mPa·s at 25°C was obtained.

[0284] The obtained isocyanurate-type polyisocyanate was mixed with the polyisocyanate composition PA1-a1 obtained in Example 1-1, such that the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups was 22 mol%, to obtain polyisocyanate composition PA1-a5.

[0285] [Examples 1-14] (Production of polyisocyanate composition PA1-a14) Polyisocyanate composition PA1-a14 was obtained by adding a light stabilizer (hindered amine compound, manufactured by BASF Japan Ltd., trade name "Tinuvin765") to the polyisocyanate composition PA1-a6 obtained in Examples 1-6 in an amount of 1.0% by mass relative to the total mass of the polyisocyanate composition.

[0286] [Examples 1-16] (Production of polyisocyanate composition PA1-a16) The inside of a four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 1200 g of HDI and 93 g of 2-ethyl-1-hexanol were charged in. The urethane reaction was carried out at 90°C for 1 hour under stirring. After raising the temperature to 130°C, 0.42 g of a mineral spirit solution containing 20% ​​by mass of zirconyl 2-ethylhexanoate was added as an allophanate catalyst. After 60 minutes, when the refractive index of the reaction solution increased to 0.0055, 3.9 g of a 2-ethyl-1-hexanol solution containing 10% by mass of pyrophosphate (manufactured by Taihei Chemical Industry Co., Ltd., trade name "Phosphoric Acid (105%)" diluted with 2-ethyl-1-hexanol) was added to stop the reaction. After filtering the reaction mixture, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under two conditions: the first at 150°C (0.2 Torr) and the second at 160°C (0.2 Torr). The resulting allophanate-type polyisocyanate compound was a clear liquid with a yield of 330 g, a viscosity of 100 mPa·s, and an NCO content of 17.4% by mass. The molar ratio of allophanate groups to isocyanurate groups was 97 / 3.

[0287] 22 parts by mass of the obtained allophanate-type polyisocyanate was mixed with 78 parts by mass of the polyisocyanate composition PA1-a15 obtained in Examples 1-15 to obtain polyisocyanate composition PA1-a16.

[0288] [Comparative Example 1-1] (Production of polyisocyanate composition PA1-b1) A four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 450 g of HDI, 74 g of PCL1, and 74 g of PCL2 were charged. The urethane reaction was carried out at 100°C for 2 hours under stirring. After filtering the reaction solution, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under the following conditions: 1st pass at 150°C (0.2 Torr), 2nd pass at 150°C (0.2 Torr), and 3rd pass at 160°C (0.2 Torr). The resulting polyisocyanate composition was liquid with a viscosity of 1,560 mPa·s and an NCO content of 9.1% by mass. The obtained polyisocyanate composition was designated PA1-b1.

[0289] [Comparative Example 1-2] (Production of polyisocyanate composition PA1-b2) Polyisocyanate composition PA1-b2 was prepared using the same method as in Example 1-1, except that the types and amounts of raw materials were as shown in the table below, and the reaction was stopped when the refractive index of the reaction solution increased to 0.0046.

[0290] <Manufacturing of paint compositions> [Examples 1-17] A paint composition was obtained by adding molecular sieves (MS) (manufactured by Union Showa Co., Ltd., trade name "3A Powder"; hereinafter sometimes referred to as "3A-MS") to the polyisocyanate composition PA1-a15 obtained in Examples 1-15 in an amount of 1.7% by mass relative to the total mass of the polyaspartic paint composition, as described in the method for producing the polyaspartic paint composition above.

[0291] The various physical properties and evaluation results are shown in the table below. The abbreviations in the table refer to the following compounds.

[0292] (Polyol) • Polyester polyol PCL1: Polycaprolactone polyol "Capa2043", manufactured by Ingevity, number-average molecular weight Mn400, average number of hydroxyl groups 2, viscosity at 25°C 246 mPa·s PCL2: Polycaprolactone polyol "Capa2085", manufactured by Ingevity, number-average molecular weight Mn830, average number of hydroxyl groups 2, viscosity at 25°C 627 mPa·s PCL3: Polycaprolactone polyol "ODX2542C", manufactured by DIC Corporation, number-average molecular weight Mn850, average number of hydroxyl groups 3, viscosity at 25°C 1,270 mPa·s PCL4: Polycaprolactone polyol "Capa2054", manufactured by Ingevity, number-average molecular weight Mn 550, average number of hydroxyl groups 2, viscosity at 25°C 360 mPa·s PCL5: Polycaprolactone polyol "Capa2067A", manufactured by Ingevity, number-average molecular weight Mn650, average number of hydroxyl groups 2, viscosity at 25°C 493 mPa·s PES: Polyester polyol "Kuraray Polyol P-510", manufactured by Kuraray Co., Ltd., number average molecular weight Mn 500, average number of hydroxyl groups 2, viscosity at 25°C 540 mPa·s

[0293] • Polyoxyalkylene polyol PPG1: "ECOTRION H1000", manufactured by SK Chemicals, number-average molecular weight Mn1000, average number of hydroxyl groups 2, viscosity at 25°C 489 mPa·s PPG2: "ECOTRION H2000", manufactured by SK Chemicals, number-average molecular weight Mn2000, average number of hydroxyl groups 2, viscosity at 25°C 1701 mPa·s PPG3: "Velvet H250", manufactured by Allessa, number-average molecular weight Mn227, average number of hydroxyl groups 2, viscosity at 25°C 107 mPa·s PTMG: "BioPTMG650", manufactured by Mitsubishi Chemical Corporation, number-average molecular weight Mn655, average number of hydroxyl groups 2, viscosity at 25°C 351 mPa·s

[0294] [Table 1-1]

[0295] [Table 1-2]

[0296] [Table 1-3]

[0297] As shown in the table above, the polyisocyanate compositions PA1-a1 to PA1-a17 (Examples 1-1 to 1-16, 1-18), which satisfy all the above-mentioned components, had a low viscosity of 3000 mPa·s or less, were easily mixed with aspartic acid ester compounds even in high-solid formulations, and showed almost no turbidity in terms of crystallinity. From this, it was inferred that when these polyisocyanate compositions were used as curing agents for polyaspartic coating compositions, they could be mixed uniformly, resulting in good curability and smoothness of the coating film. Furthermore, the appearance, weather resistance, and low-temperature elongation of the coating film obtained using polyaspartic coating compositions containing these polyisocyanate compositions were also good.

[0298] Furthermore, in a comparison of polyisocyanate compositions PA1-a1 and PA1-a2 (Examples 1-1 and 1-2) with different molar ratios of uretdione groups, a tendency was observed for the low-temperature elongation of the coating film to be superior as the molar ratio of uretdione groups decreased. On the other hand, a tendency was observed for the viscosity of the polyisocyanate composition to be lower and better as the molar ratio of uretdione groups increased.

[0299] Furthermore, in a comparison of polyisocyanate compositions PA1-a1, PA1-a3, and PA1-a4 (Examples 1-1, 1-3, and 1-4), and PA1-a14 and PA1-a16 (Examples 1-14 and 1-16), which have different molar ratios of allophanate groups to urethane groups (B / A), it was observed that the higher the molar ratio B / A, the higher the transparency of the polyisocyanate composition and the greater the suppression of crystallization. On the other hand, it was observed that the lower the molar ratio B / A, the better the weather resistance and low-temperature elongation when used as a coating film.

[0300] Furthermore, in a comparison of polyisocyanate compositions PA1-a1 and PA1-a5 (Examples 1-1 and 1-5) with different molar ratios of isocyanurate groups, it was observed that the lower the molar ratio of isocyanurate groups, the better the low-temperature elongation when used as a coating film.

[0301] Furthermore, in a comparison of polyisocyanate compositions PA1-a1, PA1-a6, PA1-a8, PA1-a10~PA1-a13, and PA1-a15 (Examples 1-1, 1-6, 1-8, 1-10~1-13, and 1-15) with different types of combined polyols, it was observed that combining two types of polyester polyols tended to result in superior weather resistance when used as a coating film. Combining two types of polyester polyols with an average number of hydroxyl groups of 2 resulted in lower viscosity and superior low-temperature elongation when used as a coating film. Furthermore, in a comparison of polyisocyanate compositions PA1-a17 (Examples 1-18) containing only one type of polyol, it was observed that combining two types of polyester polyols tended to further suppress crystallization.

[0302] Furthermore, in a comparison of polyisocyanate compositions PA1-a6 and PA1-a7 (Examples 1-6 and 1-7) with different blending ratios of polyester polyol and polyoxyalkylene polyol, it was observed that the weather resistance of the coating film tended to improve as the blending ratio of polyester polyol increased.

[0303] Furthermore, in a comparison of PA1-a8 and PA1-a9 (Examples 1-8 and 1-9), which differ in the blending ratio of polyester polyols with an average number of hydroxyl groups of 2 and polyester polyols with an average number of hydroxyl groups of 3, it was observed that the elongation of the coating film tended to improve as the blending ratio of polyester polyols with an average number of hydroxyl groups of 2 increased.

[0304] Furthermore, in a comparison of polyisocyanate compositions PA1-a6 and PA1-a14 (Examples 1-6 and 1-14), which differ in the presence or absence of UV absorbers when used as polyaspartic coating compositions, it was observed that incorporating UV absorbers tended to result in superior weather resistance when used as a coating film.

[0305] On the other hand, the polyisocyanate composition PA1-b1 (Comparative Example 1-1), which does not contain allophanate groups, exhibited turbidity and poor crystallinity. Furthermore, its appearance as a coating film was also poor.

[0306] Furthermore, in polyisocyanate compositions PA1-b2 (Comparative Examples 1-2), where the molar ratio of allophanate groups to urethane groups was 50 / 50 and greater than 30 / 70, the viscosity was high at 3100 mPa·s, making it difficult to prepare a polyaspartic coating composition by mixing it with an aspartic acid ester compound without using a solvent. In addition, the appearance, weather resistance, and low-temperature elongation of the resulting coating film were also poor.

[0307] <Production of polyisocyanate compositions> [Example 2-1] (Production of polyisocyanate composition PA2-a1) The inside of a four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 450 g of HDI, 67 g of the polycaprolactone polyol Capa2043 (manufactured by Ingevity; hereafter sometimes referred to as "PCL1"), 67 g of the polycaprolactone polyol Capa2085 (manufactured by Ingevity; hereafter sometimes referred to as "PCL2"), and 14 g of 2-ethyl-1,3-hexanediol were charged in, and the urethane reaction was carried out at 100°C for 2 hours under stirring. After raising the temperature to 130°C, 0.11 g of a 2-ethyl-1-hexanol solution containing 20% ​​by mass of zirconyl 2-ethylhexanoate was added as an allophanate catalyst. When the refractive index of the reaction solution increased to 0.001, 1.0 g of a 2-ethyl-1-hexanol solution containing 10% by mass of pyrophosphate (manufactured by Taihei Chemical Industry Co., Ltd., trade name "Phosphoric Acid (105%)" diluted with 2-ethyl-1-hexanol) was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under the following conditions: 1st pass at 150°C (0.2 Torr), 2nd pass at 150°C (0.2 Torr), and 3rd pass at 160°C (0.2 Torr). The obtained polyisocyanate composition was liquid with a viscosity of 1,720 mPa.s and an NCO content of 10.5% by mass. The molar ratio of allophanate groups to urethane groups was 10 / 90. The obtained polyisocyanate composition was designated PA2-a1.

[0308] [Examples 2-2 to 2-3, Examples 2-9 to 2-14, and Example 2-16] (Production of polyisocyanate compositions PA2-a2 to PA2-a3, PA2-a9 to PA2-a14, and PA2-a16) Each polyisocyanate composition was prepared using the same method as in Example 2-1, except that the types and amounts of raw materials were as shown in the table below.

[0309] [Examples 2-4] (Production of polyisocyanate composition PA2-a4) A four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 450 g of HDI, 67 g of PCL1, 67 g of PCL2, and 14 g of 2-ethyl-1,3-hexanediol were charged. The urethane reaction was carried out at 100°C for 2 hours under stirring. After filtering the reaction solution, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under the following conditions: 1st pass at 150°C (0.2 Torr), 2nd pass at 150°C (0.2 Torr), and 3rd pass at 160°C (0.2 Torr). The resulting polyisocyanate composition was liquid with a viscosity of 1,590 mPa.s and an NCO content of 10.1% by mass. The resulting polyisocyanate composition was designated PA2-a4.

[0310] [Examples 2-5] (Production of polyisocyanate composition PA2-a5) Polyisocyanate composition PA2-a5 was produced using the same method as in Example 2-1, except that the types and amounts of raw materials were as shown in the table below, and the reaction was stopped when the refractive index of the reaction solution increased to 0.00033.

[0311] [Examples 2-6] (Production of polyisocyanate composition PA2-a6) Polyisocyanate composition PA2-a6 was produced using the same method as in Example 2-1, except that the types and amounts of raw materials were as shown in the table below, and the reaction was stopped when the refractive index of the reaction solution increased to 0.003.

[0312] [Examples 2-7] (Preparation of polyisocyanate composition PA2-a7) A four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 450 g of HDI, 67 g of PCL1, 67 g of PCL2, and 14 g of 2-ethyl-1,3-hexanediol were charged. The urethane reaction was carried out at 100°C for 2 hours under stirring. After raising the temperature to 140°C, the allophanate reaction was carried out for 3 hours. After 3 hours, the temperature was lowered to room temperature to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under the conditions of 150°C (0.2 Torr) for the first pass, 150°C (0.2 Torr) for the second pass, and 160°C (0.2 Torr) for the third pass. The obtained polyisocyanate composition was liquid, and the molar ratio of allophanate groups to urethane groups was 10 / 90. The obtained polyisocyanate composition was designated PA2-a7.

[0313] [Examples 2-8] (Production of polyisocyanate composition PA2-a8) A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. 100 parts by mass of HDI were added, and the reactor temperature was maintained at 60°C under stirring. 0.15 parts by mass of a solution of tetrabutylammonium acetate, the isocyanurate reaction catalyst, diluted to 10% by mass with 2-ethyl-1-hexanol, was added to carry out the isocyanurate reaction. When the NCO content of the reaction solution reached 43.8% by mass, phosphoric acid was added to stop the reaction. The reaction solution was then maintained at 90°C for 1 hour. After cooling, the reaction solution was filtered, and unreacted HDI was removed using a thin-film evaporator. An isocyanurate-type polyisocyanate with an NCO content of 23.1% by mass and a viscosity of 1350 mPa·s at 25°C was obtained.

[0314] The obtained isocyanurate-type polyisocyanate was mixed with the polyisocyanate composition PA2-a1 obtained in Example 2-1, such that the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups was 22 mol%, to obtain polyisocyanate composition PA2-a8.

[0315] [Examples 2-15] (Production of polyisocyanate composition PA2-a15) Polyisocyanate composition PA2-a15 was obtained by adding a light stabilizer (hindered amine compound, manufactured by BASF Japan Ltd., trade name "Tinuvin765") to the polyisocyanate composition PA2-a9 obtained in Example 2-9 in an amount of 1.0% by mass relative to the total mass of the polyisocyanate composition.

[0316] [Examples 2-17] (Preparation of polyisocyanate composition PA2-a17) The inside of a four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 1200 g of HDI and 93 g of 2-ethyl-1-hexanol were charged in. The urethane reaction was carried out at 90°C for 1 hour under stirring. After raising the temperature to 130°C, 0.42 g of a mineral spirit solution containing 20% ​​by mass of zirconyl 2-ethylhexanoate was added as an allophanate catalyst. After 60 minutes, when the refractive index of the reaction solution increased to 0.0055, 3.9 g of a 2-ethyl-1-hexanol solution containing 10% by mass of pyrophosphate (manufactured by Taihei Chemical Industry Co., Ltd., trade name "Phosphoric Acid (105%)" diluted with 2-ethyl-1-hexanol) was added to stop the reaction. After filtering the reaction mixture, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under two conditions: the first at 150°C (0.2 Torr) and the second at 160°C (0.2 Torr). The resulting allophanate-type polyisocyanate compound was a clear liquid with a yield of 330 g, a viscosity of 100 mPa·s, and an NCO content of 17.4% by mass. The molar ratio of allophanate groups to isocyanurate groups was 97 / 3.

[0317] 21 parts by mass of the obtained allophanate-type polyisocyanate was mixed with 79 parts by mass of the polyisocyanate composition PA2-a16 obtained in Example 2-16 to obtain polyisocyanate composition PA2-a17.

[0318] [Comparative Example 2-1] (Production of polyisocyanate composition PA2-b1) A four-necked flask equipped with a stirrer, thermometer, and condenser was purged with nitrogen, and 450 g of HDI, 74 g of PCL1, and 74 g of PCL2 were charged. The urethane reaction was carried out at 100°C for 2 hours under stirring. After filtering the reaction solution, unreacted HDI was removed using a gravity-feed thin-film distillation apparatus under the following conditions: 1st pass at 150°C (0.2 Torr), 2nd pass at 150°C (0.2 Torr), and 3rd pass at 160°C (0.2 Torr). The resulting polyisocyanate composition was liquid with a viscosity of 1,560 mPa·s and an NCO content of 9.1% by mass. The resulting polyisocyanate composition was designated PA2-b1.

[0319] <Manufacturing of paint compositions> [Examples 2-18] To the polyisocyanate composition PA2-a16 obtained in Example 2-16, molecular sieves (MS) (manufactured by Union Showa Co., Ltd., trade name "3A Powder"; hereinafter sometimes referred to as "3A-MS") were added in an amount of 1.7% by mass relative to the total mass of the polyaspartic coating composition, as described in the method for producing the polyaspartic coating composition above, to obtain a coating composition.

[0320] The various physical properties and evaluation results are shown in the table below. The abbreviations in the table refer to the following compounds.

[0321] (First polyol) • Polyester polyol PCL1: Polycaprolactone polyol "Capa2043", manufactured by Ingevity, number-average molecular weight Mn400, average number of hydroxyl groups 2, viscosity at 25°C 246 mPa·s PCL2: Polycaprolactone polyol "Capa2085", manufactured by Ingevity, number-average molecular weight Mn830, average number of hydroxyl groups 2, viscosity at 25°C 627 mPa·s PCL3: Polycaprolactone polyol "ODX2542C", manufactured by DIC Corporation, number-average molecular weight Mn850, average number of hydroxyl groups 3, viscosity at 25°C 1,270 mPa·s PCL4: Polycaprolactone polyol "Capa2054", manufactured by Ingevity, number-average molecular weight Mn 550, average number of hydroxyl groups 2, viscosity at 25°C 360 mPa·s PES: Polyester polyol "Kuraray Polyol P-510", manufactured by Kuraray Co., Ltd., number average molecular weight Mn 500, average number of hydroxyl groups 2, viscosity at 25°C 540 mPa·s

[0322] • Polyoxyalkylene polyol PPG1: "ECOTRION H1000", manufactured by SK Chemicals, number-average molecular weight Mn1000, average number of hydroxyl groups 2, viscosity at 25°C 489 mPa·s PTMG: "BioPTMG650", manufactured by Mitsubishi Chemical Corporation, number-average molecular weight Mn655, average number of hydroxyl groups 2, viscosity at 25°C 351 mPa·s

[0323] (Second polyol) Diol1: 2-ethyl-1,3-hexanediol Diol2: 2,4-diethyl-1,5-pentanediol

[0324] [Table 2-1]

[0325] [Table 2-2]

[0326] [Table 2-3]

[0327] As shown in the table above, the polyisocyanate compositions PA2-a1 to PA2-a17 (Examples 2-1 to 2-17), which satisfy all the above-mentioned components, had a low viscosity of 3000 mPa·s or less, were easily mixed with aspartic acid ester compounds even in a high-solid formulation, and showed almost no turbidity in terms of crystallinity. From this, it was inferred that when these polyisocyanate compositions were used as curing agents for polyaspartic coating compositions, they could be mixed uniformly, resulting in good curability and smoothness of the coating film. Furthermore, the appearance, weather resistance, and low-temperature elongation of the coating film obtained using polyaspartic coating compositions containing these polyisocyanate compositions were also good.

[0328] Furthermore, in a comparison of polyisocyanate compositions PA2-a1 and PA2-a3 (Examples 2-1 and 2-3) with different amounts of the second polyol, it was observed that as the amount of the second polyol decreased, the viscosity became lower and better, and the low-temperature elongation of the coating film tended to be superior.

[0329] Furthermore, in a comparison of polyisocyanate compositions PA2-a1 and PA2-a4~PA2-a6 (Examples 2-1 and 2-4~2-6) with different molar ratios of allophanate groups to urethane groups (B / A), it was observed that the higher the molar ratio B / A, the greater the transparency of the polyisocyanate composition and the greater the suppression of crystallization. On the other hand, the lower the molar ratio B / A, the greater the weather resistance and low-temperature elongation of the coating film.

[0330] Furthermore, in a comparison of polyisocyanate compositions PA2-a1 and PA2-a7 (Examples 2-1 and 2-7) with different molar ratios of uretdione groups, it was observed that the lower the molar ratio of uretdione groups, the better the low-temperature elongation when applied as a coating film.

[0331] Furthermore, in a comparison of polyisocyanate compositions PA2-a1 and PA2-a8 (Examples 2-1 and 2-8) with different molar ratios of isocyanurate groups, it was observed that the lower the molar ratio of isocyanurate groups, the better the low-temperature elongation when used as a coating film.

[0332] Furthermore, in a comparison of polyisocyanate compositions PA2-a1, PA2-a9, PA2-a11, PA2-a13~PA2-a14, and PA2-a16 (Examples 2-1, 2-9, 2-11, 2-13~2-14, and 2-16) with different types of combined polyols, a tendency was observed for the weather resistance of the coating film to be superior when two types of polyester polyols were combined. A tendency was observed for the viscosity to be lower and the low-temperature elongation of the coating film to be superior when two types of polyester polyols with an average number of hydroxyl groups of 2 were combined.

[0333] Furthermore, in a comparison of polyisocyanate compositions PA2-a9 and PA2-a10 (Examples 2-9 and 2-10) with different blending ratios of polyester polyol and polyoxyalkylene polyol, it was observed that the weather resistance of the coating film tended to improve as the blending ratio of polyester polyol increased. On the other hand, it was observed that crystallization was more suppressed as the blending ratio of polyoxyalkylene polyol increased.

[0334] Furthermore, in a comparison of polyisocyanate compositions PA2-a9 and PA2-a15 (Examples 2-9 and 2-15), which differ in the presence or absence of UV absorbers when used as polyaspartic coating compositions, it was observed that incorporating UV absorbers tended to result in superior weather resistance when used as a coating film.

[0335] On the other hand, the polyisocyanate composition PA2-b1 (Comparative Example 2-1), which did not contain the second polyol, showed turbidity and poor crystallinity. Furthermore, the appearance of the coated film was also poor. [Industrial applicability]

[0336] The polyisocyanate composition of this embodiment provides a polyisocyanate composition with good viscosity, suppression of crystallization, and good appearance, weather resistance, and elongation at -20°C when formed as a coating film. The polyaspartic coating composition of this embodiment contains the polyisocyanate composition and has good appearance, weather resistance, and elongation at -20°C when formed as a coating film. The coating film of this embodiment is formed by curing the polyaspartic coating composition and has good appearance, weather resistance, and elongation at -20°C.

Claims

1. At least one diisocyanate selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, At least one polyol selected from the group consisting of polyester polyols and polyoxyalkylene polyols, It contains polyisocyanates derived from, The polyol has a number-average molecular weight of 200 or more and 2000 or less, and an average number of hydroxyl groups of 2 or 3. The aforementioned polyisocyanate contains a urethane group and an allophanate group in one molecule. The molar ratio of allophanate groups to urethane groups is 2 / 98 or more and 30 / 70 or less. A polyisocyanate composition in which the molar amount of uretdione groups relative to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.3 mol% or more and 20 mol% or less.

2. The polyisocyanate composition according to claim 1, wherein the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.01 mol% or more and 20.00 mol% or less.

3. The polyisocyanate composition according to claim 1, wherein the polyol comprises two polyester polyols having different structures, or the polyester polyol and the polyoxyalkylene polyol.

4. The polyisocyanate composition according to claim 1, wherein the content of the polyoxyalkylene polyol is 30% by mass or less relative to the total mass of the polyol.

5. The polyisocyanate composition according to claim 1, wherein the content of polyols having an average number of hydroxyl groups of 3 is 30% by mass or less relative to the total mass of polyols.

6. The polyisocyanate composition according to claim 1, which is a curing agent for polyaspartic coatings.

7. A polyaspartic coating composition comprising a polyisocyanate composition according to any one of claims 1 to 6 and an aspartic acid ester compound.

8. A coating film obtained by curing the polyaspartic coating composition according to claim 7.

9. The present invention comprises a diisocyanate, a first polyol, a second polyol, and a polyisocyanate derived from them. The aforementioned diisocyanate is at least one selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates. The first polyol has a number-average molecular weight of 200 or more and 2000 or less, an average number of hydroxyl groups of 2 or 3, and is at least one selected from the group consisting of polyester polyols and polyoxyalkylene polyols. The second polyol is a monool, diol, or triol having a branched chain with 2 to 20 carbon atoms. The molar ratio of allophanate groups to urethane groups is 0 / 100 or more and 30 / 70 or less. A polyisocyanate composition in which the molar amount of uretdione groups relative to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.3 mol% or more and 20 mol% or less.

10. The polyisocyanate composition according to claim 9, wherein the content of the second polyol is 1% by mass or more and 30% by mass or less, relative to the total mass of the first polyol and the second polyol.

11. The polyisocyanate composition according to claim 9, wherein the second polyol is a diol having a branched chain with 3 to 20 carbon atoms.

12. The polyisocyanate composition according to claim 9, wherein the molar ratio of allophanate groups to urethane groups is 2 / 98 or more and 30 / 70 or less.

13. The polyisocyanate composition according to claim 9, wherein the ratio of the molar amount of isocyanurate groups to the total molar amount of isocyanurate groups, uretdione groups, allophanate groups, and urethane groups is 0.01 mol% or more and 20.00 mol% or less.

14. The polyisocyanate composition according to claim 9, wherein the first polyol comprises two polyester polyols having different structures, or the polyester polyol and the polyoxyalkylene polyol.

15. The polyisocyanate composition according to claim 9, wherein the content of the polyoxyalkylene polyol is 30% by mass or less with respect to the total mass of the first polyol and the second polyol.

16. The polyisocyanate composition according to claim 9, wherein the content of a polyol having an average number of hydroxyl groups of 3 is 30% by mass or less with respect to the total mass of the first polyol and the second polyol.

17. The polyisocyanate composition according to claim 9, which is a curing agent for polyaspartic coatings.

18. A polyaspartic coating composition comprising a polyisocyanate composition according to any one of claims 9 to 17 and an aspartic acid ester compound.

19. A coating film obtained by curing the polyaspartic coating composition according to claim 18.

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