Polyisocyanate compositions, coating compositions, coating films, and coated articles

Abstract

To provide a polyisocyanate composition that can reduce the amount of solvent used when adjusting the viscosity of paint and has excellent curability and weather resistance when formed into a coating film. [Solution] A polyisocyanate composition obtained from an aliphatic diisocyanate containing 1,5-pentamethylene diisocyanate and a hydroxyl group-containing compound, wherein the specific molar ratio calculated from the content (mol%) of isocyanurate group, iminooxadiazinedione group, uretdione group, allophanate group, and burette group is within a specific range, and the average number of isocyanate groups is 2.7 or more and 3.4 or less.

Description

[Technical Field]

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

[0002] Polyisocyanate-based urethane paints form durable and chemically resistant coatings, and demand for them is increasing year by year. The isocyanate groups in polyisocyanate, the curing agent, react at room temperature with the hydroxyl groups of polyols (which are commonly used as main agents) or the amino groups of polyamines. As a result, paints containing these react with a wide range of substrates and have a broad range of applications. Among these, polyisocyanates made from aliphatic diisocyanates, such as 1,6-hexamethylene diisocyanate (hereinafter also simply referred to as "HDI"), are widely used in various outdoor coatings due to their excellent weather resistance when formed into a coating film.

[0003] In recent years, in order to reduce the proportion of polyisocyanates added to paints, polyisocyanates made from 1,5-pentamethylene diisocyanate (hereinafter also simply referred to as "PDI"), which has one less carbon atom than HDI, have been proposed (see, for example, Patent Document 1).

[0004] On the other hand, polyisocyanates made from PDI have a higher viscosity than polyisocyanates made from HDI, resulting in a larger amount of solvent being used when adjusting paint viscosity. From the perspective of protecting the global environment, the paint industry desires to reduce the amount of solvent used when adjusting paint viscosity.

[0005] As a technique to reduce the viscosity of polyisocyanates made from PDI, polyisocyanates containing uretdione groups as part of their structure have been proposed (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 6920999 [Patent Document 2] Patent No. 6482657 [Overview of the project] [Problems that the invention aims to solve]

[0007] In a wide range of coating applications, including automobiles, building exteriors, and industrial coatings, there is a demand for polyisocyanates that can reduce the amount of solvent used when adjusting paint viscosity and that offer excellent curability and weather resistance when formed into a coating film.

[0008] However, although the polyisocyanate described in Patent Document 1 has good curability and weather resistance when used as a coating film, its high viscosity means there is room for improvement in terms of reducing the amount of solvent used when adjusting the viscosity of the paint. Although the polyisocyanate described in Patent Document 2 has low viscosity, it has a small average number of isocyanate groups, so there is room for improvement in terms of curability and weather resistance when used as a coating film.

[0009] The present invention has been made in view of the above circumstances, and aims to provide a polyisocyanate composition that can reduce the amount of solvent used when adjusting the viscosity of paint and has excellent curability and weather resistance when formed into a coating film. Another objective is to provide a coating composition containing the polyisocyanate composition, a coating film obtained by curing the coating composition, and a coated article equipped with the coating film. [Means for solving the problem]

[0010] The inventors diligently studied to resolve the problems of the prior art described above. As a result, they discovered that a polyisocyanate composition obtained from an aliphatic diisocyanate containing PDI and a hydroxyl group-containing compound, in which a specific molar ratio calculated from the content (mol%) of isocyanurate group, iminooxadiazinedione group, uretdione group, allophanate group, and burette group is within a specific range, and the average number of isocyanate groups is between 2.7 and 3.4, can reduce the amount of solvent used when adjusting the viscosity of paints and exhibits excellent curability and weather resistance when formed into a coating film, thus completing the present invention.

[0011] In other words, embodiments of the present invention are as follows. [1] A polyisocyanate composition obtained from an aliphatic diisocyanate containing 1,5-pentamethylene diisocyanate and a hydroxyl group-containing compound, wherein a specific molar ratio 1 represented by the following formula (1) is 0.02 or more and 0.50 or less, a specific molar ratio 2 represented by the following formula (2) is 0.60 or more and 0.96 or less, and the average number of isocyanate groups is 2.7 or more and 3.4 or less. Specific molar ratio 1 = B / (A+B+C+D+E) (1) Specific molar ratio 2 = (A + B) / (A + B + C + D + E) (2) (In formulas (1) and (2), A represents the content (mol%) of isocyanurate groups represented by formula (I) below, B represents the content (mol%) of iminooxadiazinedione groups represented by formula (II) below, C represents the content (mol%) of uretdione groups represented by formula (III) below, D represents the content (mol%) of allophanate groups represented by formula (IV) below, and E represents the content (mol%) of burette groups represented by formula (V) below.) [ka] [2] The polyisocyanate composition according to [1], wherein the specific molar ratio 3 represented by the following formula (3) is 0.25 or more and 0.95 or less. Specific molar ratio 3 = A / (A+B+C+D+E) (3) In formula (3), A, B, C, D, and E have the same definitions as those shown in the above formula (1) and the above formula (2). [3] The polyisocyanate composition according to [1] or [2], wherein the specific molar ratio 4 represented by the following formula (4) is 0.01 or more and 0.10 or less. Specific molar ratio 4 = D / (A+B+C+D+E) (4) In formula (4), A, B, C, D, and E have the same definitions as those shown in the above formula (1) and the above formula (2). [4] The polyisocyanate composition according to any one of [1] to [3], wherein the isocyanate group concentration relative to the total mass of the polyisocyanate composition is 23.0% by mass or more and 27.0% by mass or less. [5] A coating composition comprising the polyisocyanate composition according to any one of [1] to [4] and a polyvalent active hydrogen compound. [6] A coating film obtained by curing the coating composition according to [5].[end]] [7] A coated article comprising the coating film according to [6].[end]] Effects of the Invention

[0012] According to the polyisocyanate composition of the present invention, the amount of solvent used during coating viscosity adjustment can be reduced, and a polyisocyanate composition excellent in curability and weather resistance when formed into a coating film can be provided. In addition, a coating composition containing the polyisocyanate composition, a coating film obtained by curing the coating composition, and a coated article including the coating film can also be provided. Mode for Carrying Out the Invention

[0013] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an illustration for describing the present invention, and is not intended to limit the present invention to the following content. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

[0014] <Polyisocyanate Composition> The polyisocyanate composition of the present embodiment comprises a polyisocyanate obtained from an aliphatic diisocyanate containing PDI and a hydroxy group-containing compound. In one aspect of the present invention, the polyisocyanate is a reaction product of an aliphatic diisocyanate containing PDI and a hydroxy group-containing compound. In the polyisocyanate composition of the present embodiment, the specific molar ratio 1 represented by the following formula (1) is 0.02 or more and 0.50 or less, the specific molar ratio 2 represented by the following formula (2) is 0.60 or more and 0.96 or less, and the average number of isocyanate groups is 2.7 or more and 3.4 or less.

[0015] Specific molar ratio 1 = B / (A+B+C+D+E) (1) Specific molar ratio 2 = (A+B) / (A+B+C+D+E) (2) (In formulas (1) and (2), A represents the content (mol%) of an isocyanurate group represented by the following formula (I), B represents the content (mol%) of an iminooxadiazinedione group represented by the following formula (II), C represents the content (mol%) of a uretdione group represented by the following formula (III), D represents the content (mol%) of an allophanate group represented by the following formula (IV), and E represents the content (mol%) of a biuret group represented by the following formula (V).)

[0016] Chemical Formula

[0017] With the above configuration, the polyisocyanate composition of the present embodiment has improved compatibility with polyvalent active hydrogen compounds, and contains components excellent in heat resistance at a constant ratio, so that the amount of solvent used when adjusting the viscosity of a coating material can be reduced, and the resulting coating film is excellent in curability and weather resistance.

[0018] The lower limit of the specific molar ratio 1 only needs to be 0.02, but is preferably 0.04, more preferably 0.08, still more preferably 0.10, and particularly preferably 0.12. When the specific molar ratio 1 is not lower than the above lower limit, the amount of solvent used when adjusting the viscosity of a coating material can be further reduced. The upper limit of the specific molar ratio 1 can be 0.50, but 0.47 is preferred, 0.44 is more preferred, 0.40 is even more preferred, and 0.32 is particularly preferred. When the specific molar ratio 1 is below the above upper limit, the weather resistance of the coating film is further improved.

[0019] The above upper and lower limits for specific molar ratio 1 can be combined arbitrarily. Examples of specific molar ratio 1 include 0.04 to 0.50, 0.08 to 0.47, 0.10 to 0.47, 0.12 to 0.47, 0.12 to 0.44, and 0.10 to 0.40.

[0020] The lower limit of the specific molar ratio 2 is 0.60, but 0.65 is preferred, 0.70 is more preferred, 0.75 is even more preferred, and 0.80 is particularly preferred. When the specific molar ratio 2 is equal to or above the above lower limit, the weather resistance of the coating film is further improved. The upper limit of the specific molar ratio 2 can be 0.96, but 0.95 is preferred, 0.94 is more preferred, 0.935 is even more preferred, and 0.93 is particularly preferred. When the specific molar ratio 2 is below the above upper limit, the compatibility with polyvalent active hydrogen compounds is further improved.

[0021] The above upper and lower limits for the specific molar ratio 2 can be combined arbitrarily. Examples of specific molar ratio 2 include 0.65 to 0.96, 0.70 to 0.96, 0.75 to 0.96, 0.80 to 0.96, and 0.60 to 0.95.

[0022] The lower limit of the average number of isocyanate groups in the polyisocyanate composition of this embodiment may be 2.7, preferably 2.75, more preferably 2.80, even more preferably 2.85, and particularly preferably 2.90. A lower limit of the average number of isocyanate groups equal to or greater than the above lower limit results in a higher crosslinking density when applied as a coating film. The upper limit of the average number of isocyanate groups mentioned above may be 3.4, preferably 3.35, more preferably 3.30, and even more preferably 3.25. By keeping the upper limit of the average number of isocyanate groups below this upper limit, the amount of solvent used when adjusting the viscosity of the paint can be further reduced.

[0023] The above upper and lower limits for the average number of isocyanate groups can be combined in any way. Examples of average numbers of isocyanate groups include 2.75 to 3.35, 2.80 to 3.30, 2.85 to 3.25, and 2.90 to 3.25.

[0024] The average number of isocyanate groups can be calculated using the following formula based on the isocyanate group concentration and the number-average molecular weight described below. Average number of isocyanate groups = (number-average molecular weight) × (isocyanate group concentration) / 100 / 42

[0025] The polyisocyanate composition of this embodiment is preferably one in which the specific molar ratio 3 represented by the following formula (3) is 0.25 or more and 0.95 or less.

[0026] Specific molar ratio 3 = A / (A+B+C+D+E) (3) (In equation (3), A, B, C, D, and E are equivalent to those shown in equations (1) and (2) above.)

[0027] The lower limit of the specific molar ratio 3 is preferably 0.25, more preferably 0.30, even more preferably 0.35, and particularly preferably 0.40. When the specific molar ratio 3 is equal to or above the above lower limit, the weather resistance of the coating film is further improved. The upper limit of the specific molar ratio 3 is preferably 0.95, more preferably 0.90, even more preferably 0.85, and particularly preferably 0.80. By keeping the specific molar ratio 3 below the above upper limit, the amount of solvent used when adjusting the paint viscosity can be further reduced.

[0028] The above upper and lower limits for the specific molar ratio 3 can be combined arbitrarily. Examples of specific molar ratio 3 include 2.75 to 3.35, 2.80 to 3.30, 2.85 to 3.25, and 2.90 to 3.25.

[0029] The polyisocyanate composition of this embodiment is preferably one in which the specific molar ratio 4 represented by the following formula (4) is 0.01 or more and 0.10 or less.

[0030] Specific molar ratio 4 = D / (A+B+C+D+E) (4) (In equation (4), A, B, C, D, and E are equivalent to those shown in equations (1) and (2) above.)

[0031] The lower limit of the specific molar ratio 4 is preferably 0.01, more preferably 0.02, even more preferably 0.03, and particularly preferably 0.04. When the specific molar ratio 4 is equal to or above the above lower limit, the compatibility with polyvalent active hydrogen compounds is improved. The upper limit of the specific molar ratio of 4 is preferably 0.10, more preferably 0.09, even more preferably 0.08, and particularly preferably 0.07. When the specific molar ratio of 4 is below the above upper limit, the drying properties and weather resistance of the coating film are better.

[0032] The upper and lower limits of the specific molar ratio 4 can be combined arbitrarily. Examples of specific molar ratio 4 include 0.01 to 0.09, 0.01 to 0.08, 0.01 to 0.07, and 0.02 to 0.09.

[0033] The polyisocyanate composition of this embodiment is preferably one in which the specific molar ratio 5 represented by the following formula (5) is 0.01 or more and 0.5 or less.

[0034] Specific molar ratio 5 = C / (A+B+C+D+E) (5) (In equation (5), A, B, C, D, and E are equivalent to those shown in equations (1) and (2) above.)

[0035] The lower limit of the specific molar ratio 5 is preferably 0.01 or higher, and more preferably 0.02 or higher. Having the specific molar ratio 5 at or above this lower limit allows for a further reduction in the amount of solvent used when adjusting the paint viscosity. The upper limit of the specific molar ratio of 5 is preferably 0.5 or less, more preferably 0.4 or less, even more preferably 0.25 or less, and particularly preferably 0.1 or less. When the specific molar ratio of 5 is below the above upper limit, the weather resistance of the coating film is further improved.

[0036] The above upper and lower limits for the specific molar ratio 5 can be combined arbitrarily. Examples of specific molar ratio 5 include 0.01 to 0.5, 0.01 to 0.4, and 0.01 to 0.25.

[0037] The specific molar ratios of 1 to 5 mentioned above can be achieved by appropriately adjusting the content of each functional group using the manufacturing method described later.

[0038] The specific molar ratios 1 to 5 are, respectively, 13 The content of each functional group can be calculated by appropriately using known methods such as 13C-NMR measurement. More specifically, it can be calculated by the method described in the examples below.

[0039] In the polyisocyanate composition of this embodiment, the isocyanate group concentration is preferably 20% to 30% by mass relative to the total mass (100% by mass) of the polyisocyanate composition, excluding unreacted diisocyanate.

[0040] The lower limit of the isocyanate group concentration is more preferably 21% by mass, even more preferably 22% by mass, and particularly preferably 23% by mass. When the isocyanate group concentration is above the above lower limit, the compatibility with polyvalent active hydrogen compounds is improved. The upper limit for the isocyanate group concentration is more preferably 29% by mass, even more preferably 28% by mass, and particularly preferably 27% by mass. By keeping the isocyanate group concentration below the above upper limit, the polyvalent active hydrogen compound and the polyisocyanate composition can be blended in nearly equal amounts, making them easier to mix more uniformly. The upper and lower limits of the isocyanate group concentration mentioned above can be combined arbitrarily. Examples of isocyanate group concentrations include 21% to 29% by mass, 22% to 28% by mass, and 23% to 27% by mass.

[0041] The isocyanate group concentration can be determined by neutralizing the isocyanate groups of the polyisocyanate composition with an excess of 2N amine, followed by back titration with 1N hydrochloric acid. More specifically, it can be measured by the titration method described in the examples below.

[0042] The number-average molecular weight of the polyisocyanate composition in this embodiment is preferably 350 or more and 700 or less.

[0043] The lower limit of the number-average molecular weight is more preferably 400, even more preferably 450, and particularly preferably 500. A number-average molecular weight of 400 or higher than the lower limit results in a higher crosslinking density when applied to a coating film. The upper limit of the number-average molecular weight is more preferably 670, even more preferably 640, and particularly preferably 600. Having the number-average molecular weight below this upper limit allows for a further reduction in the amount of solvent used when adjusting the paint viscosity. The upper and lower limits of the number-average molecular weight mentioned above can be combined arbitrarily. Examples of such number-average molecular weights include 400 to 670, 450 to 640, and 500 to 640.

[0044] The above number-average molecular weight can be measured using known methods such as gel permeation chromatography. More specifically, it can be measured by the method described in the examples below.

[0045] The viscosity of the polyisocyanate composition of this embodiment at 25°C is preferably 200 mPa·s or more and 5000 mPa·s or less. The lower limit of the viscosity is more preferably 300 mPa·s, even more preferably 400 mPa·s, and particularly preferably 500 mPa·s. When the viscosity is above the lower limit, the crosslinking density when it is formed into a coating film is higher. The upper limit of the viscosity is more preferably 4000 mPa·s, even more preferably 3500 mPa·s, and particularly preferably 3000 mPa·s. By keeping the viscosity below the upper limit, the amount of solvent used when adjusting the viscosity of the paint can be further reduced.

[0046] The upper and lower limits of viscosity mentioned above can be combined in any way. Examples of such viscosities include 300 mPa·s to 4000 mPa·s, 400 mPa·s to 3500 mPa·s, and 500 mPa·s to 3000 mPa·s.

[0047] The viscosity described above can be measured by the method described in the examples below.

[0048] In this embodiment, the aliphatic diisocyanate monomer concentration (mass%) in the polyisocyanate composition refers to the total mass of aliphatic diisocyanate monomers that remained unreacted during the production of the polyisocyanate, relative to the total mass (100 mass%) of the polyisocyanate composition. The aliphatic diisocyanate monomer concentration is preferably 1.0 mass% or less, more preferably 0.5 mass% or less, and even more preferably 0.3 mass% or less. A mass concentration of aliphatic diisocyanate monomer below the above upper limit results in a higher crosslinking density when used as a coating film.

[0049] The mass concentration of aliphatic diisocyanate monomers can be measured using known methods such as gas chromatography. More specifically, it can be measured by the method described in the examples below.

[0050] In the polyisocyanate composition of this embodiment, the solid content refers to the non-volatile components excluding volatile substances. The total mass of the solid content is not particularly limited, but is preferably 98% to 100% by mass, and more preferably 99% to 100% by mass, relative to the total mass (100% by mass) of the polyisocyanate composition.

[0051] The solid content can be measured using known methods as appropriate. More specifically, it can be measured by the method described in the examples below.

[0052] Polyisocyanates The polyisocyanate composition of this embodiment may contain a polyisocyanate obtained from PDI and a hydroxyl group-containing compound, and may further contain a polyisocyanate obtained from another aliphatic diisocyanate other than PDI and a hydroxyl group-containing compound. The polyisocyanate may be a single type or two or more types may be used in combination.

[0053] (Aliphatic diisocyanates) The aliphatic diisocyanate used as a raw material for the polyisocyanate in this embodiment may contain PDI. The aliphatic diisocyanate may be PDI alone, or it may contain PDI and other aliphatic diisocyanates.

[0054] Other aliphatic diisocyanates are not particularly limited, but aliphatic diisocyanates having 4 to 30 carbon atoms are preferred. Examples of aliphatic diisocyanates having 4 to 30 carbon atoms include, but are not limited to, 1,4-butanediisocyanate, HDI, 2,2,4-trimethyl-hexamethylene-1,6-diisocyanate, and lysine diisocyanate. Among these, 1,4-butanediisocyanate or HDI is preferred, and HDI is more preferred, from the viewpoint of having better reactivity with hydroxyl group-containing compounds, being able to further reduce the amount of solvent used when adjusting the viscosity of the paint, and having better weather resistance when formed into a coating film.

[0055] (Hydroxy group-containing compound) In this embodiment, the hydroxyl group-containing compound used as a raw material for the polyisocyanate is preferably a dihydric or less alcohol, and more preferably a monohydric alcohol, from the viewpoint of reducing viscosity. In this embodiment, the hydroxyl group-containing compound, which is a raw material for the polyisocyanate, promotes the progress of the reaction by uniformly dispersing the initiator of the isocyanuration reaction or the iminooxadiazinedione reaction. As a result, the amount of initiator used can be reduced, and discoloration of the polyisocyanate is suppressed. In addition, the hydroxyl group-containing compound reacts with the isocyanate group to form an allophanate group, which contributes to improved compatibility with the main component, resulting in good weather resistance. Examples of monohydric alcohols include, but are not limited to, methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, and branched aliphatic monoalcohols. Examples of branched aliphatic monoalcohols include isopropanol, 2-butanol, isobutanol, and 2-ethylhexanol.

[0056] Examples of dihydric alcohols include, but are not limited to, 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, 1,10-decanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, and linear aliphatic diols such as polytetramethylene glycol; and branched aliphatic diols such as 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,8-octanediol, and 2,2-diethyl-1,3-propanediol.

[0057] Among the alcohols with a hydride of 2 or less, those with 2 to 10 carbon atoms are preferred. For divalent or less alcohols, a lower limit of 3 carbon atoms is more preferable, and 4 carbon atoms is even more preferable. When the number of carbon atoms in the divalent alcohol is greater than or equal to the above lower limit, the average number of isocyanate groups increases, resulting in better drying and curing properties when used as a coating film. The upper limit for the number of carbon atoms in a divalent or less alcohol is more preferably 8, even more preferably 6, and particularly preferably 5. Having a carbon number below the above upper limit improves compatibility with polyvalent active hydrogen compounds and results in a superior appearance when applied as a coating.

[0058] The upper and lower limits for the number of carbon atoms in alcohols with a valence of 2 or less can be any combination. For example, 3 to 8 is more preferable, 4 to 6 is even more preferable, and 4 or 5 is particularly preferable.

[0059] The above-mentioned alcohols with a hydride of 2 or less may be used alone or in combination of two or more types.

[0060] The concentration of the hydroxyl group-containing compound-derived component constituting the polyisocyanate composition of this embodiment is not particularly limited, but is preferably 0.05% by mass or more and 10% by mass or less based on the total amount (100% by mass) of the polyisocyanate composition. The lower limit of the concentration of the hydroxyl group-containing compound-derived component is more preferably 0.1% by mass, even more preferably 0.15% by mass, particularly preferably 0.2% by mass, and most preferably 0.25% by mass. When the concentration of the hydroxyl group-containing compound-derived component is above the above lower limit, the compatibility with the polyvalent active hydrogen compound is improved. The upper limit for the concentration of the hydroxyl group-containing compound-derived component is more preferably 9% by mass, even more preferably 8% by mass, and particularly preferably 7% by mass. When the concentration of the hydroxyl group-containing compound-derived component is below the above upper limit, the weather resistance of the resulting coating film is superior.

[0061] The upper and lower limits for the concentration of components derived from hydroxyl group-containing compounds can be arbitrarily combined. Examples of concentrations of components derived from hydroxyl group-containing compounds include 0.1% to 9% by mass, 0.15% to 8% by mass, 0.2% to 7% by mass, and 0.25% to 7% by mass.

[0062] The concentration of components derived from hydroxyl group-containing compounds can be determined by heating the polyisocyanate composition to approximately 300°C and measuring the thermally decomposed components using GC-MS.

[0063] ≪Optional ingredients≫ The polyisocyanate composition of this embodiment may contain optional components depending on the purpose and application. For example, when storing a polyisocyanate composition, at least one selected from the group consisting of antioxidants (e.g., hindered phenols such as 2,6-di-t-butyl-p-cresol) and ultraviolet absorbers (e.g., benzotriazole and benzophenone) may be added to the polyisocyanate composition in an amount of 10 ppm to 500 ppm by mass in order to suppress discoloration during storage.

[0064] <Method for producing polyisocyanate composition> The method for producing the polyisocyanate composition of this embodiment will be described in detail below, but is not limited thereto.

[0065] The polyisocyanate composition of this embodiment uses an aliphatic diisocyanate containing PDI and a hydroxyl group-containing compound as essential raw materials.

[0066] The reaction between an aliphatic diisocyanate containing PDI and a hydroxyl group-containing compound can simultaneously carry out an isocyanuration reaction to form an isocyanurate group and an iminooxadiadindione reaction to form an iminooxadiadindione group, in the presence of an excess of aliphatic diisocyanate monomer relative to the hydroxyl group-containing compound. Among these, the molar ratio of the hydroxyl group-containing compound to the aliphatic diisocyanate monomer is preferably in the range of 100:0.01 to 100:5. After the reaction is complete, the polyisocyanate composition of this embodiment can be obtained by removing the unreacted aliphatic diisocyanate monomer. Alternatively, a polyisocyanate composition can be obtained by mixing the polyisocyanates after carrying out the above reactions separately.

[0067] From the viewpoint of simplifying the production of the polyisocyanate composition, it is preferable to carry out the above reactions simultaneously. From the viewpoint of making it easier to adjust the specific molar ratio of 1 to 5 of the polyisocyanate composition, it is preferable to carry out the reactions separately and then mix each polyisocyanate.

[0068] Furthermore, when producing the polyisocyanate composition of this embodiment, in addition to the isocyanuration reaction and the iminooxadiazinedione reaction, an allophanate reaction to form an allophanate group, a uretdione reaction to form a uretdione group, and a biuret reaction to form a biuret group may also be included. In particular, it is preferable to include either or both of the allophanate reaction and the uretdione reaction, and it is more preferable to include the allophanate reaction. The following explains each reaction.

[0069] • Isocyanuration reaction Commonly used isocyanurate reaction catalysts can be used as catalysts for deriving isocyanurate group-containing polyisocyanates from aliphatic diisocyanate monomers.

[0070] The isocyanurate reaction catalyst is not particularly limited, but one that is basic is preferred. Examples of basic isocyanurate reaction catalysts include (1) to (8) below. (1) Hydroxides of tetraalkylammonium such as tetramethylammonium, tetraethylammonium, and tetrabutylammonium; organic weak salts such as their acetate, octylate, myristicate, and benzoate. (2) Hydroxyalkylammonium hydroxides such as trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium, and triethylhydroxypropylammonium; organic weak salts such as their acetates, octylates, myristicates, and benzoates. (3) Metal salts of alkyl carboxylic acids such as acetic acid, caproic acid, octicic acid, and myristic acid, zinc of the alkyl carboxylic acids, and lead of the alkyl carboxylic acids. (4) Metal alkoxides such as sodium and potassium. (5) Aminosilyl group-containing compounds such as hexamethylene disilazane. (6) Mannich bases. (7) Combined use of tertiary amines and epoxy compounds. (8) Phosphorus compounds such as tributylphosphine.

[0071] Among the above, organic weak salts of quaternary ammonium compounds are preferred, and organic weak salts of tetraalkylammonium compounds are more preferred.

[0072] The amount of the above-mentioned isocyanurate reaction catalyst added is preferably 10 ppm by mass or more and 1000 ppm by mass or less relative to the total mass of the aliphatic diisocyanate raw material. The upper limit is more preferably 500 ppm by mass, and even more preferably 200 ppm by mass.

[0073] The isocyanuration reaction temperature is preferably 50°C to 120°C, and more preferably 60°C to 90°C. A isocyanuration reaction temperature below the above upper limit results in a polyisocyanate composition that is less prone to discoloration.

[0074] The isocyanuration reaction can be stopped at a desired conversion rate (total mass of polyisocyanate produced by the isocyanuration reaction relative to the total mass of aliphatic diisocyanate monomers charged), which can be stopped, for example, by adding an acidic compound such as phosphoric acid or an acidic phosphoric acid ester.

[0075] To obtain the polyisocyanate composition of this embodiment, it is necessary to stop the reaction in its initial stages. However, because the isocyanuration reaction has a very fast initial reaction rate, it is difficult to stop the reaction in its initial stages, and the reaction conditions, particularly the amount and method of catalyst addition, must be carefully selected. For example, a method of adding the catalyst in installments at regular intervals is recommended as a suitable approach. Therefore, the conversion rate of the isocyanurate reaction to obtain the polyisocyanate composition of this embodiment is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. By keeping the conversion rate below the above upper limit, the viscosity of the polyisocyanate composition can be further reduced.

[0076] • Iminooxadiazinedione reaction For the imino-oxadiazine reaction, for example, the following (I) or (II), which are generally known as imino-oxadiazine dione reaction catalysts, can be used. (I) Tetramethylammonium fluoride hydrate, tetraethylammonium fluoride, etc., with the general formula M[F n ], or general formula M[F n (HF) m (Poly)hydrogen fluoride represented by ] (wherein m and n are integers satisfying the relationship m / n>0, and M represents an n-charged cation (mixture) or one or more radicals with a total valency of n). (II) General formula R of 3,3,3-trifluorocarboxylic acid; 4,4,4,3,3-pentafluorobutanoic acid; 5,5,5,4,4,3,3-heptafluoropentanoic acid; 3,3-difluoropropane-2-enoic acid, etc. 1 -CR'2-C(O)O-, or general formula R 2 =CR'-C(O)O-(wherein, R 1 , and R 2 A compound comprising a quaternary ammonium cation or a quaternary phosphonium cation, wherein R' is optionally a branched, cyclic, and / or unsaturated perfluoroalkyl group having 1 to 30 carbon atoms, and R' is identical or different, selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, and an aryl group, and optionally containing a heteroatom; and a quaternary ammonium cation or a quaternary phosphonium cation.

[0077] As the catalyst for the imino-oxadiazine dionation reaction, (a) above is preferred from the viewpoint of availability, and (b) above is preferred from the viewpoint of safety. The amount of imino-oxadiazine dionation catalyst used is preferably 10 ppm by mass or more and 1000 ppm by mass or less relative to the mass of diisocyanate charged. The lower limit of the amount of imino-oxadiazinedione catalyst used is more preferably 20 ppm by mass, even more preferably 40 ppm by mass, and particularly preferably 80 ppm by mass. The upper limit for the amount of iminooxadiazinedione catalyst used is more preferably 800 ppm by mass, even more preferably 600 ppm by mass, and particularly preferably 500 ppm by mass.

[0078] Furthermore, the reaction temperature for the iminooxadiazinedione is preferably between 40°C and 120°C. The lower limit of the imino-oxadiazinedione reaction temperature is more preferably 50°C, and even more preferably 55°C. Maintaining a reaction temperature above this lower limit allows for a higher reaction rate. The upper limit for the imino-oxadiazinedione reaction temperature is more preferably 100°C, even more preferably 90°C, and particularly preferably 80°C. Keeping the reaction temperature below the upper limit makes the polyisocyanate composition less prone to discoloration.

[0079] • Allophanate reaction To generate allophanate groups, it is preferable to use an allophanate reaction catalyst. Examples of allophanate reaction catalysts include alkyl carboxylates of tin, lead, zinc, bismuth, zirconium, and zirconyl, such as organotin compounds like tin 2-ethylhexanoate and dibutyltin dilaurate, organolead compounds like lead 2-ethylhexanoate, organozinc compounds like zinc 2-ethylhexanoate, bismuth 2-ethylhexanoate, zirconium 2-ethylhexanoate, and zirconyl 2-ethylhexanoate. The allophanate reaction catalyst may be used alone or in combination of two or more types.

[0080] Furthermore, the above-mentioned isocyanurate reaction catalyst can also be used as an allophanate reaction catalyst. When the allophanate reaction is carried out using the above-mentioned isocyanurate reaction catalyst, isocyanurate group-containing polyisocyanates are naturally produced. From the viewpoint of production costs, it is preferable to use the above-mentioned isocyanurate reaction catalyst as the allophanate reaction catalyst to carry out both the allophanate reaction and the isocyanurate reaction.

[0081] • Uretdione reaction The uretdione reaction that forms the uretdione group can be obtained, for example, using a uretdione reaction catalyst. The uretdione reaction catalyst is not particularly limited, but examples include trialkylphosphines such as tri-n-butylphosphine and tri-n-octylphosphine, tris(dialkylamino)phosphine such as tris-(dimethylamino)phosphine, and cycloalkylphosphines such as cyclohexyl-di-n-hexylphosphine. Many of the uretdione reaction catalysts described above also promote the isocyanurate reaction, producing isocyanurate group-containing polyisocyanates in addition to uretdione group-containing polyisocyanates. The uretdione reaction can be stopped when the desired yield is reached. For example, the reaction can be stopped by adding a deactivator of the uretdione reaction catalyst (e.g., phosphoric acid and methyl p-toluenesulfonate). After stopping the reaction, filtration may be performed if necessary.

[0082] Furthermore, uretdione groups can also be obtained by heating aliphatic diisocyanate monomers without using the uretdione reaction catalysts described above. The heating temperature for the aliphatic diisocyanate monomer is preferably 120°C or higher, more preferably 130°C to 170°C, and even more preferably 140°C to 160°C. Furthermore, the heating time for the aliphatic diisocyanate monomer is preferably 30 minutes to 4 hours, more preferably 1 hour to 3 hours, and even more preferably 1 hour to 2 hours.

[0083] • Burette reaction A burette reaction that forms a burette bond can be obtained, for example, by reacting a so-called burette agent such as water, t-butanol, or urea with an aliphatic diisocyanate monomer under conditions where the molar ratio of (burette agent) to (isocyanate group of aliphatic diisocyanate monomer) is approximately 1 / 2 to approximately 1 / 100. These techniques are disclosed, for example, in Japanese Patent Publication No. 53-106797, Japanese Patent Publication No. 55-11452, and Japanese Patent Publication No. 59-95259.

[0084] The isocyanurate reaction, iminooxadiazinedione reaction, allophanate reaction, biuret reaction, and uretdione reaction described above can be carried out sequentially, or some of them can be carried out in parallel. In particular, it is preferable to carry out the isocyanurate reaction first, followed by the uretdione reaction. From the viewpoint of further simplifying the manufacturing process, it is even more preferable to carry out the isocyanurate reaction first, followed by the thermal uretdione reaction.

[0085] The yield (mass of the obtained polyisocyanate composition / total mass of the raw materials × 100) when producing the polyisocyanate composition of this embodiment is preferably 10% by mass or more and 70% by mass or less. The lower limit of the above yield is more preferably 14% by mass, even more preferably 18% by mass, and particularly preferably 22% by mass. A yield above the above lower limit allows for a higher average number of isocyanate groups in the resulting polyisocyanate composition. The upper limit of the above yield is more preferably 65% ​​by mass, even more preferably 60% by mass, and particularly preferably 55% by mass. By keeping the yield below the above upper limit, the viscosity of the resulting polyisocyanate composition can be further reduced. The upper and lower limits of the yield mentioned above can be combined in any way. Examples of yields include 14% to 65% by mass, 18% to 60% by mass, and 22% to 55% by mass.

[0086] <Coating composition> The coating composition of this embodiment comprises the polyisocyanate composition of this embodiment and a polyvalent active hydrogen compound. A polyvalent active hydrogen compound means a compound that contains two or more active hydrogens in its molecule that are reactive with isocyanate groups. For example, the coating composition of this embodiment can be produced by mixing the polyisocyanate composition of this embodiment with a polyvalent active hydrogen compound. These components react with each other to form a crosslinked coating film.

[0087] ≪Polyvalent Active Hydrogen Compounds≫ The polyvalent active hydrogen compound in the coating composition of this embodiment is not particularly limited, but it is preferable to include at least one selected from the group consisting of polyols, polyamines, and alkanolamines, more preferably to include either one or both of a polyol and a polyamine, and even more preferably to include a polyol.

[0088] (Polyol) The polyol is not particularly limited, but examples include polyester polyols, acrylic polyols, polyether polyols, polyolefin polyols, fluorine polyols, polycarbonate polyols, and polyurethane polyols. The polyols listed above may be used individually or in combination of two or more.

[0089] Examples of polyester polyols include the same polyester polyols exemplified above as hydroxyl group-containing compounds.

[0090] The acrylic polyol is not particularly limited, but it can be obtained by copolymerizing a monomer containing an ethylenically unsaturated bond having a hydroxyl group, either alone or in a mixture thereof, with another monomer containing an ethylenically unsaturated bond, either alone or in a mixture thereof, that is copolymerizable with the acrylic polyol.

[0091] The above-mentioned monomers containing ethylenically unsaturated bonds and having a hydroxyl group are not particularly limited, but include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and hydroxybutyl methacrylate. Among these, hydroxyethyl acrylate and hydroxyethyl methacrylate are preferred.

[0092] Other ethylenically unsaturated bond-containing monomers copolymerizable with the above monomers are not particularly limited, but include acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, benzyl acrylate, and phenyl acrylate; methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, and methacrylic acid Examples include methacrylic acid esters such as lauryl, benzyl methacrylate, and phenyl methacrylate; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid; unsaturated amides such as acrylamide, methacrylamide, N,N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, maleic acid amide, and maleimide; vinyl monomers such as glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile, and dibutyl fumarate; and vinyl monomers having hydrolyzable silyl groups such as vinyltrimethoxysilane, vinylmethyldimethoxysilane, and γ-(meth)acryloxypropyltrimethoxysilane.

[0093] Polyether polyols are not particularly limited, but examples include: hydroxides such as lithium, sodium, and potassium added to a polyvalent hydroxy compound alone or in a mixture of polyvalent hydroxy compounds; polyether polyols obtained by adding a single or mixture of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide using a strongly basic catalyst such as an alkoxide or alkylamine; polyether polyols obtained by reacting a polyfunctional compound such as ethylenediamine with an alkylene oxide; and so-called polymer polyols obtained by polymerizing acrylamide, etc., using these polyethers as a medium.

[0094] Examples of the polyhydric hydroxy compounds mentioned above include (1) to (6) below. (1) Diglycerin, ditrimethylolpropane, pentaerythritol, and dipentaerythritol, etc. (2) Sugar alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol, and rhamnitol. (3) Monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, ribodesose, (4) Disaccharides such as trehalose, sucrose, maltose, cellobiose, genthiobiose, lactose, and melibiose. (5) Trisaccharides such as raffinose, gentianose, and meletitose. (6) Tetrasaccharides such as stachyose.

[0095] The polyolefin polyol is not particularly limited, but examples include polybutadiene, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene having two or more hydroxyl groups. It is preferable that the statistical number of hydroxyl groups per molecule of the polyol (hereinafter also referred to as the "average number of hydroxyl groups") is 2.0 or higher. Having an average number of hydroxyl groups of 2.0 or higher in the polyol makes it less likely for the crosslinking density of the resulting coating film to decrease.

[0096] Fluorine polyols are polyols containing fluorine in their molecule, and examples include copolymers of fluoroolefins, cyclovinyl ethers, hydroxyalkyl vinyl ethers, and vinyl monocarboxylate esters, as disclosed in Japanese Patent Publication No. 57-34107 and Japanese Patent Publication No. 61-275311.

[0097] Polycarbonate polyols are not particularly limited, but examples include those obtained by condensation polymerization of dialkyl carbonates such as dimethyl carbonate; alkylene carbonates such as ethylene carbonate; diaryl carbonates such as diphenyl carbonate; and low molecular weight carbonate compounds such as diphenyl carbonate; and low molecular weight polyols used in the polyester polyols mentioned above.

[0098] Polyurethane polyols are not particularly limited, but can be obtained by reacting a polyol with a polyisocyanate using conventional methods. Examples of polyols that do not contain carboxyl groups include low molecular weight polyols such as ethylene glycol and propylene glycol, and high molecular weight polyols such as acrylic polyols, polyester polyols, and polyether polyols.

[0099] The hydroxyl group value per resin of the polyol shown above is preferably 10 mg KOH / g resin or more and 300 mg KOH / g resin or less. A hydroxyl group value of 10 mg KOH / g resin or more per resin makes it less likely for the crosslinking density to decrease, and sufficient weather resistance of the coating film can be achieved. On the other hand, a hydroxyl group value of 300 mg KOH / g resin or less per resin makes it less likely for the crosslinking density to increase excessively, and a higher level of adhesion of the coating film to the substrate when it is bent can be maintained.

[0100] Among the polyols listed above, acrylic polyols or polyester polyols are preferred. In coating compositions using polyols, the equivalent ratio (NCO:OH) of polyisocyanate groups to hydroxyl groups of the polyol is preferably 10:1 to 1:10.

[0101] (Polyamines) Examples of polyamines, though not particularly limited, include diamines such as ethylenediamine, propylenediamine, butylenediamine, triethylenediamine, hexamethylenediamine, 4,4'-diaminodicyclohexylmethane, piperazine, 2-methylpiperazine, and isophoronediamine; chain-like polyamines having three or more amino groups such as bishexamethylenetriamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentamethylenehexamine, and tetrapropylenepentamine; and cyclic polyamines such as 1,4,7,10,13,16-hexazacyclooctadecane, 1,4,7,10-tetraazacyclodecane, 1,4,8,12-tetraazacyclopentadecane, and 1,4,8,11-tetraazacyclotetradecane.

[0102] In particular, polyamines having two or more primary or secondary amino groups per molecule are preferred, and among these, those having three or more primary or secondary amino groups per molecule are more preferred.

[0103] (Alkanolamine) Alkanolamines are compounds that have an amino group and a hydroxyl group in one molecule. Examples of alkanolamines, though not particularly limited, include monoethanolamine, diethanolamine, aminoethylethanolamine, N-(2-hydroxypropyl)ethylenediamine, mono-, di-(n- or iso-)propanolamine, ethylene glycol-bis-propylamine, neopentanolamine, and methylethanolamine.

[0104] ≪Optional ingredients≫ The coating composition of this embodiment may contain optional components depending on the purpose and application. Optional components include ultraviolet absorbers such as benzotriazole and benzophenone, light stabilizers such as hindered amines and hindered phenols represented by dibutylhydroxytoluene, organic pigments such as quinacridone, pigment red, and phthalocyanine blue, inorganic pigments such as titanium dioxide and carbon black, metallic pigments such as aluminum powder, light interference pigments such as pearl mica powder, curing accelerators such as tin compounds, zinc compounds, and amine compounds, and various solvents. The solvent is not particularly limited, but examples include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as ethyl acetate, n-butyl acetate, and cellosolve acetate; and alcohols such as butanol and isopropyl alcohol. The optional components may be used alone or in combination of two or more.

[0105] <coating film> The coating film of this embodiment is formed when the coating composition of this embodiment has hardened. The coating film of this embodiment can be formed by applying the coating composition of this embodiment to an article using a coating method such as roll coating, curtain flow coating, and spray coating. This coating method includes applying the coating onto a base coat containing a pigment. The pigment can be any organic pigment, inorganic pigment, metallic pigment, light interference pigment, etc., as described above. The coating film in this embodiment is preferably formed with a dry film thickness of approximately 10 μm to 100 μm.

[0106] <Painted items> The painted article of this embodiment may be any article that has the coating film of this embodiment, for example, an article that has a coating film on an automobile or the like. This embodiment

[0107] <Usage> The polyisocyanate composition of this embodiment is useful in a wide range of fields, including new car paints, automotive refinish paints, and plastic paints. In particular, the polyisocyanate composition of this embodiment can be suitably used in high-solid paints from the viewpoint of reducing the amount of solvent used when adjusting paint viscosity. It can also be suitably used as a clear paint that does not contain pigments, and as a paint with excellent acid rain resistance or weather resistance. [Examples]

[0108] The embodiment will be described in more detail below with reference to examples, but this embodiment is not limited to these examples. The following describes methods for measuring and evaluating various physical properties. Unless otherwise specified, "parts" and "%" refer to "parts by mass" and "mass%", respectively.

[0109] [Physical property 1: Isocyanate group concentration (mass%)] The isocyanate group concentration (mass%) of polyisocyanate or polyisocyanate composition was determined by measurement as follows. First, 1 to 3 g of polyisocyanate or polyisocyanate composition was accurately weighed (Wg) into an Erlenmeyer flask. Next, 20 mL of toluene was added to the flask and the polyisocyanate or polyisocyanate composition was completely dissolved. Then, 10 mL of a 2 N toluene solution of di-n-butylamine was added to the flask and thoroughly mixed, and the mixture was left at room temperature for 15 minutes. Next, 70 mL of isopropyl alcohol was added to this solution and thoroughly mixed. This solution was titrated with a 1 N hydrochloric acid solution (factor F) using an indicator to obtain a titration value of V2 mL. The same titration procedure was performed without using polyisocyanate or polyisocyanate composition to obtain a titration value of V1 mL. From the obtained titration values ​​V2 mL and V1 mL, the isocyanate group concentration (mass%) of the polyisocyanate or polyisocyanate composition was calculated based on the following formula. Isocyanate group concentration (mass%) = (V1-V2) × F × 42 / (W × 1000) × 100

[0110] [Physical property 2: Number average molecular weight] The number-average molecular weight of polyisocyanates or polyisocyanate compositions was determined by measuring the number-average molecular weight relative to polystyrene using gel permeation chromatography (hereinafter abbreviated as "GPC") with the following apparatus. Equipment: Tosoh Corporation's "HLC-8120GPC" (product name) Column: 1 x "TSKgel SuperH1000" (product name) manufactured by Tosoh Corporation. "TSKgel SuperH2000" (product name) x 1 bottle "TSKgel SuperH3000" (product name) x 1 bottle Carrier: Tetrahydrofuran Detection method: Differential refractometer

[0111] [Physical property 3: Average number of isocyanate groups] The average number of isocyanate groups in a polyisocyanate or polyisocyanate composition was calculated using the following formula, based on the isocyanate group concentration obtained in [Physical Property 1] above and the number-average molecular weight obtained in [Physical Property 2] above. Average number of isocyanate groups = (number-average molecular weight) × (isocyanate group concentration) / 100 / 42

[0112] [Physical property 4: Viscosity (mPa s)] The viscosity of polyisocyanates or polyisocyanate compositions 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. 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) 1.0 rpm (when pressure is between 5120 mPa·s and less than 10240 mPa·s) 0.5 rpm (when pressure is between 10240 mPa·s and less than 20480 mPa·s)

[0113] [Physical property 5: Aliphatic diisocyanate monomer concentration (mass%)] The mass concentration of aliphatic diisocyanate monomer in polyisocyanates or polyisocyanate compositions was determined as follows. First, a 20 mL sample bottle was placed on a digital balance, and approximately 1 g of the sample was weighed accurately. Next, 0.03 to 0.04 g of nitrobenzene (internal standard solution) was added and weighed accurately. Then, approximately 9 mL of ethyl acetate was added. Finally, the lid of the sample bottle was tightly closed and the mixture was thoroughly mixed to prepare the sample for measurement. Using the above prepared solution, the aliphatic diisocyanate monomer concentration was quantified by gas chromatography analysis under the following conditions. (Analysis conditions) Equipment: “GC-8A” manufactured by SHIMADZU Column: Shinwa Chemical Co., Ltd. "Silicone OV-17" Column oven temperature: 120℃ Injection / Detector Temperature: 160℃

[0114] [Physical property 6: Solid content (mass%)] The solid content (non-volatile content) was measured as follows. First, an aluminum pan with a base diameter of 38 mm was accurately weighed. Next, approximately 1 g of polyisocyanate or polyisocyanate composition was placed on the aluminum pan and weighed again (W1). Then, the polyisocyanate or polyisocyanate composition was adjusted to a uniform thickness and held in an oven at 105°C for 1 hour. After the aluminum pan had cooled to room temperature, the polyisocyanate or polyisocyanate composition remaining on the aluminum pan was accurately weighed (W2). The solid content was determined from the obtained precision values ​​W1 and W2 using the following formula. Solid content (mass%)=W2 / W1×100

[0115] [Physical Property 7: Content of each functional group (mol%) and specific molar ratio] 13 The content of each functional group in the polyisocyanate or polyisocyanate composition was measured by C-NMR measurement, and the following specific molar ratios 1 to 5 were obtained respectively.

[0116] 13 The conditions for C-NMR measurement are as follows. (Analysis Conditions) 13 C-NMR apparatus: AVANCE600 (manufactured by Bruker) Cryoprobe (manufactured by Bruker) Cryo Probe 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 (complete proton decoupling method, waiting time 2 sec)

[0117] The content of each functional group was obtained by dividing the integrated value of each signal by the number of carbons to be measured. Content of isocyanurate group (mol%, hereinafter represented by "A"): around 148.6 ppm: integrated value ÷ 3 Content of iminooxadiazinedione group (mol%, represented by "B"): around 144.6 ppm: integrated value ÷ 1 Content of uretdione group (mol%, hereinafter represented by "C"): around 157.5 ppm: integrated value ÷ 2 Content of allophanate group (mol%, hereinafter represented by "D"): around 154 ppm: integrated value ÷ 1 Content of biuret group (mol%, hereinafter represented by "E"): around 155.8 ppm: (integrated value - integrated value of allophanate group) ÷ 2

[0118] Specific molar ratios 1 to 5 were obtained respectively using the following calculation formulas (1) to (5). Specific molar ratio 1 = B / (A+B+C+D+E) (1) Specific molar ratio 2 = (A + B) / (A + B + C + D + E) (2) Specific molar ratio 3 = A / (A+B+C+D+E) (3) Specific molar ratio 4 = D / (A+B+C+D+E) (4) Specific molar ratio 5 = C / (A+B+C+D+E) (5)

[0119] [Evaluation 1: Solvent usage] Acrylic polyol Ac1, produced in Production Example 8 described below, and a polyisocyanate composition prepared with butyl acetate to a solid content of 85% by mass were mixed so that NCO / OH (ratio of the molar amount of isocyanate groups in the polyisocyanate composition to the molar amount of hydroxyl groups in acrylic polyol Ac1) = 1.1. The resulting mixture was then diluted with a thinner made by mixing 40 parts by mass of solvent naphtha and 60 parts by mass of butyl acetate so that the elution time at 23°C was 23 seconds using a Ford cup viscometer (No. 4, manufactured by Taiyu Kikai Co., Ltd.). After measuring the volume and mass of the paint following viscosity adjustment, the amount of volatile organic solvent components (g / L) was calculated from the amounts of acrylic polyol Ac1, polyisocyanate composition, butyl acetate, and thinner present in the paint. The ability to reduce solvent usage was then evaluated according to the following criteria. A lower amount of volatile organic solvent components indicated a reduction in solvent usage (evaluations a and b), while a higher amount indicated a reduction in solvent usage (evaluation c).

[0120] (Evaluation Criteria) a: Volatile organic solvent content is less than 420 g / L b: Volatile organic solvent content is 420 or more but less than 435 g / L c: Volatile organic solvent content is 435 g / L or more

[0121] [Evaluation 2: Curing properties when used as a coating] Acrylic polyol Ac1, produced in Production Example 8 described below, and a polyisocyanate composition were blended at NCO / OH = 1.1, and butyl acetate was added to the coating composition so that the solid content of the coating composition was 60% by mass. The prepared coating composition was applied to a polypropylene plate and cured at 23°C and 50% RH for 24 hours. Approximately 0.2 g of the obtained coating film was immersed in approximately 40 g of acetone at 20°C for 24 hours, and the value of the undissolved coating film mass after immersion was calculated relative to the coating film mass before immersion (100% by mass). The obtained value was used as an indicator of the curability of the coating film, and the curability was evaluated according to the following criteria. A larger amount of undissolved coating film mass was evaluated as indicating better curability of the coating film (evaluations a, b), and a smaller amount of undissolved coating film mass was evaluated as indicating poor curability of the coating film (evaluation c).

[0122] (Evaluation Criteria) a: 80% by mass or more b: 75% or more in mass and less than 80% in mass c: Less than 75% mass

[0123] [Evaluation 3: Solvent resistance when used as a coating] Acrylic polyol Ac1, produced in Production Example 8 described below, and a polyisocyanate composition were blended at an NCO / OH ratio of 1.1, and butyl acetate was used to prepare a mixture with a solid content of 60% by mass. The prepared coating composition was applied to a glass plate by spraying to a dry film thickness of 50 μm. The coated glass plate was baked at 80°C for 30 minutes. After baking, it was left to stand for 7 days at 23°C and 50% RH. A cotton swab was dipped in gasohol (a mixture of gasoline and methanol in a mass ratio of 85 / 15), and the coating was rubbed 25 times. After letting it stand for 1 minute, the cotton swab was dipped in gasohol again, and the coating was rubbed 25 times. In the following evaluation criteria, the first 25 rubbings will be referred to as "the first round," and the following 25 rubbings will be referred to as "the second round."

[0124] (Evaluation Criteria) a: No changes were observed in the coating after the second application. b: After the second application, a mark was left on the paint film. c: Dissolution of the coating film was observed in the second application. d: Dissolution of the coating film was observed after the first application.

[0125] [Evaluation 4: Weather resistance when used as a coating] (Preparing a whiteboard) A solvent-based two-component urethane paint (product name "Mighty Rack (White)", manufactured by Nippon Paint Co., Ltd.) was spray-painted onto an aluminum plate (150mm x 75mm x 1mm, model number: Al050P (JIS H4000), manufactured by Test Piece Co., Ltd.) to a dry film thickness of 50 μm. After that, it was left to stand for two weeks at 23°C and 50% RH, and then the surface was sanded with #1000 grit sandpaper to create a white plate.

[0126] Acrylic polyol Ac1, produced in Production Example 8 described below, and a polyisocyanate composition were blended at NCO / OH = 1.1, and butyl acetate was used to prepare a solid content of 60% by mass. The prepared coating composition was applied to the aforementioned white board by spraying to a dry film thickness of 50 μm. The coated white board was baked at 140°C for 30 minutes. After baking, it was left to stand for 3 days at 23°C and 50% RH.

[0127] (Accelerated weathering test) After standing, accelerated weathering tests were performed using a "Dew Panel Weather Meter (DPW)" (manufactured by Suga Test Instruments Co., Ltd.). The gloss retention rate was calculated after 1100 hours or 1250 hours of accelerated weathering testing.

[0128] (Gloss retention rate) The gloss retention rate was calculated based on the following formula. The gloss level was measured in accordance with JIS Z8741. Gloss retention rate (%) = (Gloss level after accelerated weathering test) ÷ (Gloss level before accelerated weathering test) × 100

[0129] The conditions for measuring glossiness are as follows: Equipment used: "FDP / DPWL-5W" (manufactured by Suga Test Instruments Co., Ltd.) Light source: Ultraviolet fluorescent lamp: "SUGA-FS40" (wavelength 313nm) Conditions: The following cycle operation: irradiation (4 hours), darkness + humidification (4 hours). During irradiation Black panel temperature: 60℃ Humidity not set Irradiation intensity 30W / m 2 Darkness + Wet Black panel temperature: 40℃ Humidity 100% Irradiance: Not set

[0130] The weather resistance was evaluated using the calculated gloss retention rate according to the following criteria. A higher gloss retention rate indicated better weather resistance (evaluations a and b), while a lower gloss retention rate indicated poor weather resistance (evaluation c).

[0131] (Evaluation Criteria) a: When the gloss retention rate is 95% or higher even after 1250 hours. b: When the gloss retention rate after 1250 hours is less than 95%, and the gloss retention rate after 1100 hours is 95% or more. c: If the gloss retention rate after 1100 hours is less than 95%

[0132] [Production Example 1: Polyisocyanate p-1] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was placed under a nitrogen atmosphere. Next, 100 parts by mass of PDI were added to the flask, and the flask temperature was maintained at 60°C under stirring. Then, a 5% n-butanol solution of tetramethylammonium fluoride tetrahydrate was added as a catalyst component at a concentration of 110 ppm by mass relative to the total mass of PDI. Subsequently, the flask temperature was maintained below 70°C under stirring, and when the isocyanate group concentration of the reaction solution reached 46.4% by mass, the reaction was stopped by adding dibutyl phosphate at a concentration of 660 ppm by mass relative to the total mass of PDI. The resulting reaction solution was filtered, and unreacted PDI was removed using a thin-film evaporator to obtain polyisocyanate p-1. The physical properties of the obtained polyisocyanate p-1 are shown in Table 1A below.

[0133] [Manufacturing Example 2: Polyisocyanate p-2] Polyisocyanate p-2 was obtained in the same manner as described in Production Example 1, except that the temperature inside the flask was maintained at 60°C under stirring, 400 ppm by mass of a 70% isopropanol solution of tetrabutylphosphonium hydrogen difluoride was added as a catalyst component, and the reaction was stopped by adding a 40% isopropanol solution of p-toluenesulfonic acid when the isocyanate group concentration in the reaction solution reached 47.3% by mass. The physical properties of the obtained polyisocyanate p-2 are shown in Table 1A below.

[0134] [Manufacturing Example 3: Polyisocyanate p-3] Polyisocyanate p-3 was obtained in the same manner as described in Production Example 1, except that the flask temperature was maintained at 60°C under stirring, 100 ppm by mass of an 8% 2-ethylhexanol solution of tetrabutylammonium acetate was added as a catalyst component relative to the total mass of PDI, 0.2 parts by mass of n-butanol was added as a hydroxyl group-containing compound, and the reaction was stopped by adding phosphoric acid when the isocyanate group concentration in the reaction solution reached 46.4% by mass. The physical properties of the obtained polyisocyanate p-3 are shown in Table 1A below.

[0135] [Production Example 4: Polyisocyanate p-4] Polyisocyanate p-4 was obtained in the same manner as described in Production Example 3, except that the flask temperature was maintained at 60°C under stirring, 200 ppm by mass of an 8% 2-ethylhexanol solution of tetrabutylammonium acetate was added as a catalyst component relative to the total mass of PDI, 0.39 parts by mass of n-butanol was added as a hydroxyl group-containing compound, and the reaction was stopped by adding phosphoric acid when the NCO content of the reaction solution reached 41.0% by mass. The physical properties of the obtained polyisocyanate p-4 are shown in Table 1B below.

[0136] [Manufacturing Example 5: Polyisocyanate p-5] Polyisocyanate p-5 was obtained in the same manner as described in Production Example 1, except that the temperature inside the flask was maintained at 60°C under stirring, 10,000 ppm by mass of tri-n-butylphosphine was added as a catalyst component, and the reaction was stopped by adding methyl-p-toluenesulfonate when the NCO content of the reaction solution reached 42.5% by mass. The physical properties of the obtained polyisocyanate p-5 are shown in Table 1B below.

[0137] [Manufacturing Example 6: Polyisocyanate p-6] Polyisocyanate p-6 was obtained in the same manner as described in Production Example 1, except that 100 parts by mass of HDI was charged, a 10% 2-ethylhexanol solution of tetrabutylammonium acetate was added at 140 ppm by mass relative to the total mass of HDI as a catalyst component, 0.29 parts by mass of n-butanol was added as a hydroxyl group-containing compound, and the reaction was stopped by adding phosphoric acid when the NCO content of the reaction solution reached 39.4% by mass. The physical properties of the obtained polyisocyanate p-6 are shown in Table 1B below.

[0138] [Production Example 7: Polyisocyanate p-7] Polyisocyanate p-7 was obtained in the same manner as described in Production Example 1, except that HDI was used instead of PDI, a 5% n-butanol solution of tetramethylammonium fluoride tetrahydrate was added as a catalyst component at a rate of 120 ppm by mass relative to the total mass of HDI, and dibutyl phosphate was added at a rate of 720 ppm by mass relative to the total mass of HDI when the isocyanate group concentration in the reaction solution reached 43.0% by mass. The physical properties of the obtained polyisocyanate p-7 are shown in Table 1B below.

[0139] [Table 1A]

[0140] [Table 1B]

[0141] [Manufacturing Example 8: Acrylic Polyol Ac1] First, the following monomer components and initiator were added to a plastic container and mixed to form a mixture.

[0142] (Monomer components) Styrene: 10 parts by mass, n-butyl methacrylate: 36 parts by mass, n-butyl acrylate: 12 parts by mass, 2-hydroxyethyl acrylate: 21 parts by mass, 4-hydroxybutyl acrylate: 20 parts by mass, acrylic acid: 1 part by mass.

[0143] (Initiator) tert-butylperoxy-2-ethylhexanoate: 20 parts by mass (product name: Perbutyl O, manufactured by Nippon Oil & Fats Co., Ltd.)

[0144] Next, a four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel was placed under a nitrogen atmosphere. 15 parts by mass of propylene glycol monomethyl ether acetate and 8 parts by mass of solvent naphtha were added to the flask, and the solvent was heated to 140°C. After raising the temperature, the above mixture was added dropwise to the solvent from a dropping funnel over a period of 1.5 hours. After the addition was complete, the solvent to which the mixture had been added was held at 140°C for 1.5 hours. Subsequently, the solvent to which the mixture had been added was cooled to obtain acrylic polyol Ac1. The physical properties of the obtained acrylic polyol Ac1 were: solid content: 70% by mass, viscosity at 25°C: 800 mPa·s, and resin hydroxyl value: 180 mgKOH / g.

[0145] [Example 1: Production of Polyisocyanate Composition P-1] A four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube was placed under a nitrogen atmosphere. 50 parts by mass of polyisocyanate p-1 and 50 parts by mass of polyisocyanate p-5 were added to the flask and stirred at 50°C for 1 hour to obtain polyisocyanate composition P-1. The physical properties of the obtained polyisocyanate composition P-1 are shown in Table 2.

[0146] [Examples 2-7: Production of polyisocyanate compositions P-2-P-7] Polyisocyanate compositions P-2 to P-7 were obtained in the same manner as described in Example 1, except that the composition of the polyisocyanate composition was as shown in Table 2. The physical properties of the obtained polyisocyanate compositions P-2 to P-7 are shown in Table 2.

[0147] [Comparative Examples 1-5: Production of Polyisocyanate Compositions Q-1-Q-5] Polyisocyanate compositions Q-1 to Q-5 were obtained in the same manner as described in Example 1, except that the composition of the polyisocyanate composition was as shown in Table 3. The physical properties of the obtained polyisocyanate compositions Q-1 to Q-5 are shown in Table 3.

[0148] The results of evaluating the reduction in solvent usage during paint viscosity adjustment, curability, solvent resistance, and weather resistance of the polyisocyanate compositions of Examples 1-7 and Comparative Examples 1-5 are shown in Tables 2 and 3 below.

[0149] [Table 2]

[0150] [Table 3]

[0151] As shown in Table 2 above, the polyisocyanate compositions of Examples 1 to 7 (P-1 to 7) were found to reduce the amount of solvent used when adjusting the viscosity of the paint, and to exhibit excellent curability, solvent resistance, and weather resistance when formed into a coating film.

[0152] On the other hand, as shown in Table 3 above, the polyisocyanate compositions of Comparative Examples 1 to 5 (Q-1 to 5) were all poor, with at least one evaluation selected from the group consisting of solvent usage during paint viscosity adjustment, curability when formed into a coating film, solvent resistance when formed into a coating film, and weather resistance when formed into a coating film, all of which were rated as c.

[0153] As shown in Table 2 above, the polyisocyanate compositions of Examples 1, 2, 4, and 5 (P-1, 2, 4, and 5), in which the specific molar ratio 1 is 0.18 or more and 0.42 or less, were found to be able to reduce the amount of solvent used when adjusting the viscosity of paints more effectively than the polyisocyanate compositions of Examples 4, 6, and 7 (P-4, 6, and 7), in which the specific molar ratio 1 is 0.04 or more and 0.10 or less.

[0154] As shown in Table 2 above, the polyisocyanate compositions of Examples 1-3 and 7 (P-1-3, 7), in which a specific molar ratio 1 is 0.10 or more and 0.35 or less, and a specific molar ratio 2 is 0.92 or more and 0.96 or less, were found to have superior weather resistance when used as a coating film compared to the polyisocyanate compositions of Examples 4-6 (P-4-6), in which a specific molar ratio 1 is 0.04 or more and 0.42 or less, and a specific molar ratio 2 is 0.65 or more and 0.95 or less.

[0155] As shown in Table 3 above, the polyisocyanate composition (Q-1) of Comparative Example 1, which had an average number of isocyanate groups of 3.5, a specific molar ratio of 1 of 0.01, and a specific molar ratio of 2 of 0.98, received a poor evaluation of c for the amount of solvent used when adjusting the viscosity of the paint.

[0156] As shown in Table 3 above, the polyisocyanate composition (Q-2) of Comparative Example 2, which had an average number of isocyanate groups of 2.3 and a specific molar ratio of 0.23, received a rating of c for poor curability and weather resistance when used as a coating film.

[0157] As shown in Table 3 above, the polyisocyanate composition of Comparative Example 3 (Q-3), in which the specific molar ratio 1 was 0.52, and the polyisocyanate composition of Comparative Example 4 (Q-4), in which the specific molar ratio 2 was 0.44, both received a poor weather resistance rating of c when used as a coating film.

[0158] As shown in Table 3 above, the polyisocyanate composition of Comparative Example 5 (Q-5) did not contain PDI, and therefore its solvent resistance evaluation when used as a coating film was poor, rated as c. [Industrial applicability]

[0159] The polyisocyanate composition according to the present invention is useful in a wide range of fields, including new car paints, automotive refinish paints, and plastic paints. In particular, the polyisocyanate composition according to the present invention can be suitably used as a high-solid paint, a clear paint that does not contain pigments, or a paint with excellent acid rain resistance or weather resistance.

Claims

1. Obtained from an aliphatic diisocyanate containing 1,5-pentamethylene diisocyanate and a hydroxyl group-containing compound, The specific molar ratio 1 represented by the following formula (1) is 0.02 or more and 0.50 or less, The specific molar ratio 2 represented by the following formula (2) is 0.60 or more and 0.96 or less, and the average number of isocyanate groups is 2.7 or more and 3.4 or less. Polyisocyanate composition. Specific molar ratio 1 = B / (A + B + C + D + E) (1) Specific molar ratio 2 = (A + B) / (A + B + C + D + E) (2) (In formulas (1) and (2), A represents the content (mol%) of isocyanurate groups represented by formula (I) below, B represents the content (mol%) of iminooxadiazinedione groups represented by formula (II) below, C represents the content (mol%) of uretdione groups represented by formula (III) below, D represents the content (mol%) of allophanate groups represented by formula (IV) below, and E represents the content (mol%) of burette groups represented by formula (V) below.) 【Chemistry 1】

2. The polyisocyanate composition according to claim 1, wherein the specific molar ratio 3 represented by the following formula (3) is 0.25 or more and 0.95 or less. Specific molar ratio 3 = A / (A + B + C + D + E) (3) (In formula (3), A, B, C, D, and E are the same as those shown in formulas (1) and (2) above.)

3. The polyisocyanate composition according to claim 1 or 2, wherein the specific molar ratio 4 represented by the following formula (4) is 0.01 or more and 0.10 or less. Specific molar ratio 4 = D / (A + B + C + D + E) (4) (In formula (4), A, B, C, D, and E are the same as those shown in formulas (1) and (2) above.)

4. The polyisocyanate composition according to claim 1 or 2, wherein the concentration of isocyanate groups relative to the total mass of the polyisocyanate composition is 23.0% by mass or more and 27.0% by mass or less.

5. A coating composition comprising the polyisocyanate composition according to claim 1 or 2 and a polyvalent active hydrogen compound.

6. A coating film obtained by curing the coating composition according to claim 5.

7. A painted article comprising the coating film described in claim 6.

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