Catalyst composition, blocked polyisocyanate composition, coating composition, coating film, and method for forming coating film

Abstract

A catalyst composition for dissociating a blocking agent from a blocked polyisocyanate, the catalyst composition containing a quaternary ammonium salt and a diester carbonate compound.

Description

Technical Field

[0001] This disclosure relates to catalyst compositions, end-capped polyisocyanate compositions, coating compositions, coating films, and methods for forming coating films. Background Technology

[0002] Polyisocyanates have been known as curing agents used in coatings and the like. For example, polyurethane resin coatings made by combining polyols and polyisocyanates are known to have excellent abrasion resistance, chemical resistance, and stain resistance.

[0003] Coatings using polyisocyanates as curing agents are generally two-component compositions, in which the main agent (e.g., polyol) and the polyisocyanate are stored separately and mixed during application. However, once mixed, the coating cures quickly, resulting in problems such as short usability and workability during application. Furthermore, because polyisocyanates readily react with water, it is impossible to use these coatings in water-based coatings such as electrodeposited coatings.

[0004] As a solution to these problems, a method is known to deactivate polyisocyanates by reacting them with a capping agent. The capped polyisocyanates obtained by this method do not react with the main agent (polyol, etc.) at room temperature, but upon heating, the capping agent dissociates and regenerates isocyanate groups, which then react with the main agent to form crosslinks. Therefore, according to the above method, the main agent and curing agent can be pre-mixed for coating without being limited by the usable period, and polyisocyanates can also be used in water-based coatings.

[0005] As a catalyst for dissociating the capping agent from the capping polyisocyanate (capping agent dissociation catalyst), quaternary ammonium salts are known, for example (see Patent Document 1).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 08-170048 Summary of the Invention

[0009] The problem the invention aims to solve

[0010] Based on the aforementioned quaternary ammonium salt, low-temperature curing properties can be imparted to coating compositions containing end-capped polyisocyanates. On the other hand, quaternary ammonium salts are prone to color changes (e.g., yellowing) over time, and the color-changed quaternary ammonium salt may discolor the coating film. Patent Document 1 describes that curing resins using specific quaternary ammonium salts exhibit superior resistance to yellowing compared to curing resins using organometallic catalysts, but it does not describe the color change of quaternary ammonium salts over time.

[0011] Therefore, in one aspect of this disclosure, the objective is to provide a catalyst composition that not only imparts low-temperature curing properties to coating compositions containing end-capped polyisocyanates, but also is less prone to color changes over time.

[0012] Solution for solving the problem

[0013] Through research conducted by the inventors of this disclosure, it was surprisingly discovered that the color change of the quaternary ammonium salt over time is suppressed in mixtures of quaternary ammonium salts and diester compounds. This disclosure is based on the aforementioned discovery of the inventors.

[0014] This disclosure provides at least the following[1]~

[12] . [1]

[0016] A catalyst composition for dissociating a capping agent from a capped polyisocyanate.

[0017] It contains quaternary ammonium salts and carbonate diester compounds. [2]

[0019] According to the catalyst composition described in [1], the ratio of the content of the aforementioned diester compound to the content of the aforementioned quaternary ammonium salt is 0.05 to 50 by mass. [3]

[0021] According to the catalyst composition described in [1] or [2], wherein the aforementioned quaternary ammonium salt comprises the quaternary ammonium cation represented by the following formula (1).

[0022]

[0023] In equation (1), R 1 R represents an alkyl group having 1 to 16 carbon atoms, optionally having a hydroxyl, amino, or alkoxy group as a substituent. 2 ~R 4 Each can independently represent an alkyl group having 1 to 8 carbon atoms. [4]

[0025] The catalyst composition according to any one of [1] to [3], wherein the aforementioned diester compound comprises the compound shown in formula (2) below.

[0026]

[0027] In equation (2), R 5 and R 6 Each independently represents an aliphatic saturated hydrocarbon group having 1 to 16 carbon atoms, R 5 With R 6 They can be arbitrarily connected to form a loop. [5]

[0029] The catalyst composition according to any one of [1] to [4] further contains an alcohol compound. [6]

[0031] A capped polyisocyanate composition comprising a capped polyisocyanate and a catalyst composition as described in any one of [1] to [5]. [7]

[0033] According to the capped polyisocyanate composition described in [6], the content of the aforementioned quaternary ammonium salt is 0.0001 to 40 parts by weight relative to 100 parts by weight of the aforementioned capped polyisocyanate. [8]

[0035] The end-capped polyisocyanate composition according to [6] or [7], wherein the aforementioned end-capped polyisocyanate comprises a structure derived from an aliphatic polyisocyanate having 4 to 6 carbon atoms or a derivative thereof. [9]

[0037] The end-capped polyisocyanate composition according to any one of [6] to [8], wherein the aforementioned end-capped polyisocyanate has at least one group selected from the group consisting of isocyanate groups end-capped with oxime-based end-capping agents and isocyanate groups end-capped with pyrazole-based end-capping agents.

[10]

[0039] A coating composition comprising a base agent and a curing agent.

[0040] The aforementioned curing agent comprises a capped polyisocyanate, and the aforementioned main agent or curing agent comprises any one of the catalyst compositions described in [1] to [5], or,

[0041] The aforementioned curing agent comprises any one of the end-capped polyisocyanate compositions described in [6] to [9].

[11]

[0043] A coating film formed from the coating composition described in

[10] .

[12]

[0045] A method for forming a coating film includes applying the coating composition described in

[10] to a substrate and heating it at 60 to 100°C to cure the coating film formed by the aforementioned coating composition.

[0046] The effects of the invention

[0047] According to one aspect of this disclosure, a catalyst composition can be provided that not only imparts low-temperature curing properties to coating compositions containing end-capped polyisocyanates, but also is less prone to color changes over time. Detailed Implementation

[0048] In the following description, exemplary embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. It should be noted that in this specification, the numerical range represented by "~" indicates the range in which the values ​​before and after "~" are respectively the minimum and maximum values. In addition, unless otherwise specified, the units of the values ​​before and after "~" are the same. Furthermore, the upper and lower limits individually described can be arbitrarily combined.

[0049] <Catalyst Composition>

[0050] One embodiment of this disclosure is a catalyst composition containing a quaternary ammonium salt and a diester compound. This catalyst composition is used to dissociate a capping agent from a capped polyisocyanate.

[0051] According to the above catalyst composition, low-temperature curing properties can be imparted to coating compositions containing end-capped polyisocyanates. Furthermore, the above catalyst composition is less prone to color changes over time (e.g., yellowing), and it can also help reduce color changes during the manufacturing process of the coating film (before and after curing). Therefore, according to the above catalyst composition, a coating film with minimal coloration can be easily formed.

[0052] (Quaternary ammonium salt)

[0053] Quaternary ammonium salts contain quaternary ammonium cations as cationic groups. Known compounds that serve as end-capping agents and dissociation catalysts can be used as quaternary ammonium salts.

[0054] Quaternary ammonium cations are represented, for example, by the following formula (1).

[0055]

[0056] In equation (1), R 1 ~R 4 Each group independently represents a hydrocarbon group. R 1 ~R 4 They can be the same as each other, or they can be different from each other.

[0057] The hydrocarbon group can be an aliphatic hydrocarbon group (e.g., alkyl or cycloalkyl) or an aromatic hydrocarbon group (e.g., aryl). From the viewpoint of improving low-temperature curing properties and reducing color changes and coating coloration over time, the hydrocarbon group can be an aliphatic hydrocarbon group. When the aliphatic hydrocarbon group is alkyl, the aforementioned effects tend to be further enhanced.

[0058] When the hydrocarbon group is an aliphatic hydrocarbon group, its carbon number is, for example, 1 to 16. The aliphatic hydrocarbon group can have 3 or more carbons, or 12 or less carbons, or 8 or less carbons. When the hydrocarbon group is an aromatic hydrocarbon group, its carbon number is, for example, 6 to 16. The aromatic hydrocarbon group can have 8 or more carbons, or 10 or more carbons, or 14 or less carbons, or 12 or less carbons.

[0059] The hydrocarbon group may have substituents. Examples of substituents include hydroxyl, amino, and alkoxy groups. The number of carbon atoms in the alkoxy group can be, for example, 1-8, 1-6, 1-4, or 1-2. Examples of alkoxy groups include methoxy, ethoxy, butoxy, propoxy, pentoxy, and hexoxy groups. The number of substituents can be, for example, 0-3. It should be noted that the number of carbon atoms in the substituent is included in the number of carbon atoms in the hydrocarbon group.

[0060] In one embodiment, R in equation (1) 1 R represents an alkyl group having 1 to 16 carbon atoms, optionally having a hydroxyl, amino, or alkoxy group as a substituent. 2 ~R 4 Each alkyl group independently represents a carbon group with 1 to 8 carbon atoms. When using this quaternary ammonium salt, coating compositions with superior low-temperature curing properties can be easily obtained.

[0061] As R 1 Specific examples of the alkyl groups may include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, 2-propylheptyl, nonyl, decyl, isodecyl, dodecyl, hexadecyl, etc. These groups may be substituted by one or more substituents (e.g., hydroxyl, amino, or alkoxy).

[0062] From the viewpoint that it is easy to obtain coating compositions with even better low-temperature curing properties, R in formula (1) 1 It can be an alkyl or hydroxyalkyl group with 1 to 16 carbon atoms without substituents. Wherein, R 1 When the alkyl group having 1 to 16 carbon atoms is unsubstituent, the improvement in low-temperature curing properties tends to be even greater. From the viewpoint of further improving this effect, alkyl groups having 1 to 10 carbon atoms are preferred as unsubstituent alkyl groups having 1 to 16 carbon atoms. When the unsubstituent alkyl group having 1 to 16 carbon atoms is an alkyl group having 1 to 4 carbon atoms, the above effect becomes more significant. On the other hand, when the unsubstituent alkyl group having 1 to 16 carbon atoms is an alkyl group having 4 to 8 carbon atoms, the effect of reducing color change over time and coloring of the coating tends to be even greater. This tendency is significant when the alkyl group has 6 to 8 carbon atoms (especially n-octyl).

[0063] As R 2 ~R 4Specific examples of the alkyl groups represented include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, etc.

[0064] From the viewpoint that it is easy to obtain coating compositions with even better low-temperature curing properties, R in formula (1) 2 ~R 4 It can be an alkyl group with 1 to 4 carbon atoms. From the viewpoint of further improving the low-temperature curing property, the alkyl group with 1 to 4 carbon atoms is preferably an alkyl group with 1 to 2 carbon atoms, and more preferably a methyl group.

[0065] Based on the above viewpoints, the quaternary ammonium cation can be R in formula (1). 1 It is an alkyl group with 1 to 10 carbon atoms, R 2 ~R 4 It is a cation of an alkyl group having 1 to 4 carbon atoms. Preferred examples of such cations include trimethyl mono-n-octylammonium cation, trimethyl mono-n-butylammonium cation, tetramethylammonium cation, and tetrabutylammonium cation, with trimethyl mono-n-octylammonium cation being the most preferred.

[0066] The anionic group of a quaternary ammonium salt can be a group derived from the anions of acids such as organic acids and inorganic acids, or a group derived from the anions of esters such as carbonates. The anionic group of a quaternary ammonium salt can also be a group that does not belong to any of these groups (e.g., hydroxyl group (hydroxyl ion)).

[0067] Examples of fatty acid radicals (organic acid groups) derived from the anions of organic acids include fatty acid radicals. The number of carbon atoms in a fatty acid radical (aliphatic monocarboxylic acid radical) can be, for example, 1 to 12, 1 to 7, or 1 to 3. Specific examples of fatty acid radicals include formate, acetate, 2-ethylhexanoate (octanoate), laurate, cyclohexanecarboxylate, and neopentanoate.

[0068] Examples of groups (inorganic acid radicals) formed from the anions of inorganic acids include halogen groups (fluorine, chlorine, bromine, etc.), bicarbonate, and carbonate.

[0069] Examples of monoalkyl carbonates (ester groups) derived from the anion of esters include monoalkyl carbonates. The alkyl group in a monoalkyl carbonate can have, for example, 1 to 8 carbon atoms, or 1 to 4 or 1 to 2 carbon atoms. Specific examples of monoalkyl carbonates include methyl carbonate, ethyl carbonate, propyl carbonate, and butyl carbonate.

[0070] From the viewpoint of easily obtaining coating compositions with superior low-temperature curing properties, the anionic group of the quaternary ammonium salt can be a fatty acid ion with 1 to 12 carbon atoms, a monoalkyl carbonate ion with 1 to 8 carbon atoms, or a hydroxyl group. From the viewpoint of further improving the low-temperature curing properties, the anionic group can be a fatty acid ion with 1 to 7 carbon atoms or a monoalkyl carbonate ion with 1 to 4 carbon atoms. From the viewpoint of further improving this effect, it can be a monoalkyl carbonate ion with 1 to 2 carbon atoms.

[0071] Based on the above viewpoint, quaternary ammonium salts can be composed of a combination of a quaternary ammonium cation and a fatty acid ion having 1 to 12 carbon atoms, a monoalkyl carbonate ion having 1 to 8 carbon atoms, or a hydroxyl group, wherein the quaternary ammonium cation is the quaternary ammonium cation represented by formula (1) above, and R in formula (1) 1 R represents an alkyl group having 1 to 16 carbon atoms, optionally having a hydroxyl, amino, or alkoxy group as a substituent. 2 ~R 4 Each alkyl group independently represents an alkyl group having 1 to 8 carbon atoms. Preferably, R is used. 1 It is an alkyl group with 1 to 10 carbon atoms, R 2 ~R 4 It is a combination of an alkyl cation having 1 to 4 carbon atoms and a monoalkyl carbonate or hydroxyl group having 1 to 8 carbon atoms; more preferably, it is R. 1 It is an alkyl group with 4 to 8 carbon atoms, R 2 ~R 4 It is a combination of an alkyl cation having 1 to 2 carbon atoms and a monoalkyl carbonate having 1 to 8 carbon atoms.

[0072] Specific examples of quaternary ammonium salts include trimethyl mono-n-octylammonium bicarbonate, trimethyl mono-n-octylammonium methyl carbonate, trimethyl mono-n-octylammonium carbonate, trimethyl mono-n-butylammonium methyl carbonate, trimethyl mono-n-butylammonium acetate, tetramethylammonium acetate, hexadecyltrimethylammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, trimethyl(2-hydroxypropyl)ammonium 2-ethylhexanoate, tetramethylammonium bicarbonate, tetraethylammonium bicarbonate, and tetrapropylammonium carbonate. Bicarbonate, tetra-n-butylammonium bicarbonate, triethylmonomethylammonium bicarbonate, tri-n-propylmonomethylammonium bicarbonate, tri-n-butylmonomethylammonium bicarbonate, tri-n-butylmonoethylammonium bicarbonate, tetramethylammonium monomethyl carbonate, tetraethylammonium monoethyl carbonate, tetra-n-butylammonium monobutyl carbonate, triethylmonomethylammonium monomethyl carbonate, tri-n-propylmonomethylammonium monomethyl carbonate, tri-n-butylmonomethylammonium monomethyl carbonate, tri-n-butylmonoethylammonium monoethyl carbonate, tetramethylammonium carbonate, tetra-n-butylammonium carbonate.

[0073] The catalyst composition may contain one or more quaternary ammonium salts.

[0074] From the viewpoint of easily obtaining coating compositions with superior low-temperature curing properties, the quaternary ammonium salt content, based on the total mass of the catalyst composition, can be 1% by mass or more, or 5% by mass or more, 10% by mass or more, 20% by mass or more, or 30% by mass or more. From the viewpoint of further reducing color change over time and coating film tinting, the quaternary ammonium salt content, based on the total mass of the catalyst composition, can be 99% by mass or less, or 95% by mass or less, 90% by mass or less, 60% by mass or less, 40% by mass or less, 20% by mass or less, or 10% by mass or less. From these viewpoints, the quaternary ammonium salt content, based on the total mass of the catalyst composition, can be, for example, 1-99% by mass, 5-99% by mass, 10-99% by mass, 20-95% by mass, 30-90% by mass, 1-60% by mass, 1-40% by mass, 1-20% by mass, or 1-10% by mass.

[0075] (diesel carbonate compound)

[0076] Dicarbonate compounds are, for example, compounds represented by the following formula (2).

[0077]

[0078] In equation (2), R 5 and R 6 Each independently represents a hydrocarbon group, R 5 With R 6 They can be arbitrarily connected to form a loop. R 5 With R 6 They can be the same as each other, or they can be different from each other.

[0079] The hydrocarbon group can be an aliphatic hydrocarbon group (e.g., alkyl, alkylene, cycloalkyl, or cycloalkylene) or an aromatic hydrocarbon group (e.g., aryl or arylene). When the hydrocarbon group is aliphatic, the effect of reducing color change over time and improving the coloration of the coating is more pronounced. From the viewpoint of further enhancing this effect, the hydrocarbon group can be an aliphatic saturated hydrocarbon group.

[0080] When the hydrocarbon group is an aliphatic hydrocarbon group, its carbon number is, for example, 1 to 16. The aliphatic hydrocarbon group can have 1 or more carbons, or 12 or less carbons, or 8 or less carbons. When the hydrocarbon group is an aromatic hydrocarbon group, its carbon number is, for example, 6 to 16. The aromatic hydrocarbon group can have 8 or more carbons, or 10 or more carbons, or 14 or less carbons, or 12 or less carbons.

[0081] The hydrocarbon group may have substituents. Examples of substituents include hydroxyl, amino, and alkoxy groups. The number of carbon atoms in the alkoxy group can be, for example, 1 to 8, 1 to 6, 1 to 4, or 1 to 2. Examples of alkoxy groups include methoxy, ethoxy, butoxy, propoxy, pentoxy, and hexoxy groups. The number of substituents can be, for example, 0 to 3.

[0082] In one embodiment, R in equation (2) 5 and R 6 Each group consists of an aliphatic saturated hydrocarbon group with 1 to 16 carbon atoms. Using this carbonate diester compound can further reduce color changes over time and the coloring of the coating.

[0083] R 5 and R 6 The aliphatic saturated hydrocarbon group can be an alkyl group. Specific examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, 2-propylheptyl, nonyl, decyl, isodecyl, dodecyl, hexadecyl, etc.

[0084] R 5 With R 6 Aliphatic saturated hydrocarbon groups can be linked together to form alkylene groups. As a result of R... 5 With R 6 Specific examples of alkylene groups formed by their interconnection include ethylene, 1,2-propylene, 1,2-butylene, 2,3-butylene, etc.

[0085] From the perspective of improving and reducing color changes over time and the colorfastness of the coating, R 5 and R 6 Each can be an alkyl group having 1 to 4 carbon atoms (methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, or tert-butyl). R 5 and R 6 When the alkyl group has 1 to 2 carbon atoms (methyl or ethyl), the above effect tends to be enhanced. 5 and R 6 When the substance is methyl, the above effects tend to be further enhanced.

[0086] Specific examples of carbonate diester compounds include dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate, diisopropyl carbonate, diisobutyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, methyl butyl carbonate, ethyl propyl carbonate, ethyl butyl carbonate, ethylene carbonate, propylene carbonate, butyl carbonate, 2,3-butylene carbonate, and diphenyl carbonate.

[0087] The catalyst composition may contain one or more carbonate compounds.

[0088] The ratio of the content of the carbonate diester compound to the content of the quaternary ammonium salt (content of carbonate diester compound / content of quaternary ammonium salt) by mass can be 0.05 to 50. When the above ratio is 0.05 or higher, the color of the coating film tends to be reduced more, and when the above ratio is 50 or lower, it is easy to obtain a coating composition with better low-temperature curing properties. From these viewpoints, the above ratio can be 0.1 or higher, 0.3 or higher, 1 or higher, 2 or higher, 3 or higher, 4 or higher, 5 or higher, or 10 or higher; it can be 40 or lower, 30 or lower, 20 or lower, 10 or lower, 6 or lower, 5.5 or lower, or 5 or lower; it can be 0.1 to 40, 0.3 to 30, 1 to 20, 2 to 10, 3 to 6, 3 to 5.5, 3 to 5, 4 to 50, 5 to 50, or 10 to 50. Using R in formula (1) as the quaternary ammonium cation represented by the above formula (1). 1 It is an alkyl group with 4 to 8 carbon atoms, R 2 ~R 4 When a quaternary ammonium salt (e.g., trimethyl mono-n-octylammonium cation or trimethyl mono-n-butylammonium cation) is formed by combining an alkyl cation having 1 to 4 carbon atoms with a monoalkyl carbonate having 1 to 8 carbon atoms, if the above ratio is 4 or more, there is a tendency to further improve the effect of reducing color change over time and the coloring of the coating film.

[0089] (Other ingredients)

[0090] The catalyst composition may also contain components other than quaternary ammonium salts and carbonate diester compounds. Alcohol compounds can be listed as such components. By using alcohol compounds, there is a tendency to improve the effects of suppressing color changes of quaternary ammonium salts, reducing coating coloration, and improving low-temperature curing properties. The reason for this effect is not yet clear, but it is speculated that the alcohol compounds act as solvents in the catalyst composition, dissolving the quaternary ammonium salts and carbonate diester compounds. This facilitates the effect of the carbonate diester compounds on the quaternary ammonium salts, and the dissolution of the quaternary ammonium salts and carbonate diester compounds improves the homogeneity of the reaction system, thereby enhancing the catalyst activity.

[0091] Alcohol compounds can be monohydric alcohols (compounds with one hydroxyl group) or polyhydric alcohols (compounds with two or more hydroxyl groups). When using monohydric alcohols as alcohol compounds, there is a tendency to improve the low-temperature curing properties and reduce the coloring of the coating film.

[0092] The molecular weight of the alcohol compound can be, for example, 18~1000, 18~700, or 18~500. When the molecular weight of the alcohol compound is below 500, the improvement in low-temperature curing properties and the reduction in coating color tend to be more pronounced.

[0093] From the viewpoint of further reducing the coloration of the catalyst composition and coating, the alcohol compound can be an aliphatic alcohol. Aliphatic alcohols can be linear or branched. The number of carbon atoms in aliphatic alcohols can be 1-30, 1-10, 1-6, or 1-4.

[0094] Specific examples of alcohol compounds include methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, 2-ethylhexanol, 3,3,5-trimethyl-1-hexanol, n-tridecanool, 2-tridecanool, 2-octyldodecanool, pentadecanool, palmitol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol, cyclohexane-methanol, dodecanool, hexacosanol, ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 1,6-Hexanediol, 3-Methyl-1,5-pentanediol, 1,8-Octanediol, 1,9-Nonanediol, 1,10-Decanediol, Neopentanediol, 2,2-Diethyl-1,3-propanediol, 2-n-Butyl-2-ethyl-1,3-propanediol, 2,2,4-Trimethyl-1,3-pentanediol, 2-Ethyl-1,3-hexanediol, 2-n-Hexadecane-1,2-ethylenediol, 2-n-Eicosane-1,2-ethylenediol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, etc. Among these, the use of methanol tends to further enhance the improvement in low-temperature curing properties and reduce the coloration of the coating film.

[0095] The catalyst composition may contain one or more alcohol compounds.

[0096] The ratio of alcohol content to quaternary ammonium salt content (alcohol content / quaternary ammonium salt content) by mass can be 0.05 to 50. When the above ratio is 0.05 to 50, it becomes easier to obtain a coating composition with better low-temperature curing properties, and there is a greater tendency for color change and film coloring over time to be reduced. From the viewpoint of obtaining this effect more significantly, the above ratio can be 0.1 or more, 1 or more, 5 or more, or 10 or more; it can be 40 or less, 30 or less, or 20 or less; and it can be 0.05 to 40, 0.1 to 50, 1 to 30, 5 to 20, or 10 to 20.

[0097] From the perspective of suppressing the color change of quaternary ammonium salts, reducing the coloration of the coating film, and further improving the low-temperature curing properties, the content of alcohol compounds can be 80-98% by mass, based on the total mass of the catalyst composition. Similarly, from the same perspective, the content of alcohol compounds can be 80% or more by mass, or 85% or more by mass, or 98% or less by mass, or 97% or less by mass, or 80-97% or 85-98% by mass, based on the total mass of the catalyst composition.

[0098] The catalyst composition may contain end-capping agent dissociation catalyst other than quaternary ammonium salt. The content of end-capping agent dissociation catalyst other than quaternary ammonium salt in the catalyst composition is based on the total mass of end-capping agent dissociation catalyst and may be 0 to 0.5% by mass, or less than 0.2% by mass or less than 0.1% by mass.

[0099] The catalyst composition can be modulated by mixing quaternary ammonium salts, diester compounds, and any other components included.

[0100] <Capped Polyisocyanate Compositions>

[0101] One embodiment of this disclosure is a terminal polyisocyanate composition comprising a terminal polyisocyanate, a quaternary ammonium salt, and a carbonate diester compound. The terminal polyisocyanate composition may include the catalyst composition of the above embodiment. That is, the terminal polyisocyanate composition may be a composition comprising a terminal polyisocyanate and the catalyst composition of the above embodiment.

[0102] Since the above-mentioned end-capped polyisocyanate composition contains quaternary ammonium salts and carbonate diester compounds, it can impart low-temperature curing properties to the coating composition. Furthermore, for the same reason, based on the above-mentioned end-capped polyisocyanate composition, a coating composition that does not easily undergo color change during the manufacturing process of the coating film (before and after the coating film cures) can be obtained.

[0103] (Terminated polyisocyanate)

[0104] End-capped polyisocyanates are compounds derived from polyisocyanates that do not have isocyanate groups capped by an end-capping agent (hereinafter also referred to as "unend-capped polyisocyanates"), and have at least a structure derived from unend-capped polyisocyanates and isocyanate groups capped by an end-capping agent (hereinafter also referred to as "end-capped polyisocyanates").

[0105] [Unclosed polyisocyanates]

[0106] Unclosed polyisocyanates are compounds having multiple isocyanate groups (free isocyanate groups). Examples of unclosed polyisocyanates include aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and their polyisocyanate derivatives. Examples of derivatives include isocyanurate, allophanate, and biuret.

[0107] From the perspective of improving the yellowing resistance of cured coatings, uncapped polyisocyanates do not necessarily have aromatic rings. That is, uncapped polyisocyanates can be non-aromatic polyisocyanates. Examples of non-aromatic polyisocyanates include aliphatic polyisocyanates such as hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine triisocyanate, and trioxane-ethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated tetramethylxylene diisocyanate; and their derivatives. Examples of derivatives include isocyanurate esters, urea-formate esters, and biuret esters. The derivative can be an isocyanate-containing prepolymer obtained by reacting the above-mentioned polyisocyanate with a polyol, or a derivative of the prepolymer (e.g., isocyanurate, urea-formate, biuret, etc.). As the polyol, a diol having 2 to 9 carbon atoms can be used, for example. Examples of such diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol.

[0108] From the perspective of further improving low-temperature curing properties, uncapped polyisocyanates can contain aliphatic polyisocyanates or their derivatives with 4 to 6 carbon atoms. From the perspective of further improving low-temperature curing properties, uncapped polyisocyanates can contain hexamethylene diisocyanate or its derivatives. In other words, capped polyisocyanates can have a structure derived from aliphatic polyisocyanates or their derivatives with 4 to 6 carbon atoms, or they can have a structure derived from hexamethylene diisocyanate or its derivatives. Derivatives of aliphatic polyisocyanates with 4 to 6 carbon atoms (e.g., hexamethylene diisocyanate) can be at least one selected from the group consisting of isocyanurates, ureaformates, and biuret. These derivatives can be derivatives of the aforementioned isocyanate-containing prepolymers. When the derivative of hexamethylene diisocyanate is an isocyanurate, there is a tendency to obtain higher coating film hardness. When uncapped polyisocyanates contain isocyanurate groups, from the perspective of further improving coating film hardness, based on the total mass of the uncapped polyisocyanates, the content of isocyanurate trimers (isocyanurate trimer content) can be 50% by mass or more, and the content of isocyanurate groups relative to the total (100 mol%) of isocyanurate groups and urea-formate groups in the uncapped polyisocyanates (isocyanurate group content) can be greater than 80 mol%. The upper limit of the above-mentioned isocyanurate trimer content can be 80% by mass, and the upper limit of the above-mentioned isocyanurate group content can be 99 mol.

[0109] [Terminated isocyanate group]

[0110] The capped isocyanate group is an isocyanate group that is capped by a capping agent and has a structure derived from the capping agent.

[0111] Examples of end-capping agents include, for instance, alcohol-based end-capping agents such as methanol, ethanol, n-butanol, isobutanol, 2-ethylhexanol, butyl cellosolve, propylene glycol monomethyl ether, ethylene glycol, and benzyl alcohol; phenol-based end-capping agents such as phenol, cresol, ethylphenol, butylphenol, and 2-hydroxypyridine; lactam-based end-capping agents such as ε-caprolactam, δ-valerolactam, and γ-butyrolactam; oxime-based end-capping agents such as formaldehyde oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, methyl isobutyl ketone oxime, and cyclohexanone oxime; and imidazole, 2-methylimidazole, 4-methylimidazole, 2,4-dimethylimidazole, and 2-ethylhexanol. Imidazole-based end-capping agents include 2-propylimidazole, 2-isopropylimidazole, 4-methyl-2-propylimidazole, 2-phenylimidazole, 4-phenylimidazole, 5-phenylimidazole, 2-methyl-4-phenylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, and 2-heptadecanylimidazole; pyrazole-based end-capping agents include 3,5-dimethylpyrazole, 3-methylpyrazole, and pyrazole; amine-based end-capping agents include diphenylamine, diisopropylamine, and isopropylethylamine; and triazole-based end-capping agents include triazole, 1,2,4-triazole, and 3,5-dimethyl-1,2,4-triazole. From the viewpoint of storage stability, oxime-based end-capping agents can be used. Methylethyl ketone oxime is preferred as an oxime-based end-capping agent. From the viewpoint of curability, pyrazole-based end-capping agents can be used. 3,5-dimethylpyrazole is preferred as a pyrazole-based end-capping agent.

[0112] Based on the above viewpoint, in one embodiment, the capped polyisocyanate may have at least one group selected from the group consisting of isocyanate groups capped with oxime-based capping agents and isocyanate groups capped with pyrazole-based capping agents.

[0113] Terminal polyisocyanates can have free isocyanate groups, but the absence of free isocyanate groups in terminal polyisocyanates can further improve storage stability. From the perspective of further improving storage stability, all effective isocyanate groups in terminal polyisocyanates can be terminal isocyanate groups. Here, effective isocyanate groups refer to both free isocyanate groups and terminal isocyanate groups.

[0114] End-capped polyisocyanates can be obtained, for example, by reacting an unend-capped polyisocyanate or other polyisocyanate with a free isocyanate group with the end-capping agent. That is, the end-capped polyisocyanate can be the reaction product of a polyisocyanate with a free isocyanate group and the end-capping agent. The polyisocyanate with a free isocyanate group and the end-capping agent can each be used alone or in combination of two or more. However, when aromatic polyisocyanates are not used as the polyisocyanate with a free isocyanate group, the yellowing resistance of the cured coating film can be further improved.

[0115] Terminally capped polyisocyanates can be compounds derived from the reaction product of a polyisocyanate having a free isocyanate group and a capping agent. Terminally capped polyisocyanates can be compounds obtained, for example, by reacting the reaction product of a polyisocyanate having a free isocyanate group and a capping agent with a compound capable of reacting with the free isocyanate group in the reaction product (e.g., a compound containing an active hydrogen group).

[0116] The reaction of polyisocyanates with free isocyanate groups with end-capping agents can be carried out under typical end-capping reaction conditions. This reaction can be conducted at room temperature or under heating. Regardless of heating, the temperature of the reaction solution can be, for example, 20–200 °C.

[0117] Terminal polyisocyanates can be used alone or in combination of two or more. For example, two or more terminal polyisocyanates derived from different types of unterminated polyisocyanates can be used in combination.

[0118] From the viewpoint of easily obtaining coating compositions with superior low-temperature curing properties, the content of capped polyisocyanates can be 40% by mass or more, or 60% by mass or more, or 80% by mass or more, based on the total solid content of the capped polyisocyanate composition. From the viewpoint of improving the storage stability of coatings, the content of capped polyisocyanates can be less than 100% by mass, or 95% by mass or less, or 90% by mass or less, based on the total solid content of the capped polyisocyanate composition. From these viewpoints, the content of capped polyisocyanates can be, for example, 40% by mass or more and less than 100% by mass, or 60-95% by mass or 80-90% by mass, based on the total solid content of the capped polyisocyanate composition. It should be noted that the so-called total solid content of the capped polyisocyanate composition, when the capped polyisocyanate composition contains solvent, refers to the amount obtained by subtracting the amount of solvent from the total amount of the capped polyisocyanate composition; when the capped polyisocyanate composition does not contain solvent, it refers to the total amount of the capped polyisocyanate composition.

[0119] (Quaternary ammonium salts and diester compounds)

[0120] The details of the quaternary ammonium salt and the diester compound are the same as those of the quaternary ammonium salt and the diester compound contained in the catalyst composition. Furthermore, the ratio of the diester compound content to the quaternary ammonium salt content can be the same range exemplified by the ratio of the diester compound content to the quaternary ammonium salt content in the catalyst composition.

[0121] From the viewpoint of easily obtaining coating compositions with superior low-temperature curing properties, the content of the quaternary ammonium salt relative to 100 parts by weight of the capped polyisocyanate can be 0.0001 parts by weight or more, or 0.001 parts by weight or more, 0.01 parts by weight or more, 0.1 parts by weight or more, or 1 part by weight or more. From the viewpoint of improving the storage stability of the coating, the content of the quaternary ammonium salt relative to 100 parts by weight of the capped polyisocyanate can be 40 parts by weight or less, 30 parts by weight or less, 20 parts by weight or less, 10 parts by weight or less, or 5 parts by weight or less. From these viewpoints, the content of the quaternary ammonium salt relative to 100 parts by weight of the capped polyisocyanate can be, for example, 0.0001 to 40 parts by weight, 0.001 to 30 parts by weight, 0.01 to 20 parts by weight, 0.1 to 10 parts by weight, or 1 to 5 parts by weight. When the capped polyisocyanate composition contains a catalyst composition, the content of the catalyst composition can be adjusted so that the content of the quaternary ammonium salt falls within the above-mentioned ranges.

[0122] (Other ingredients)

[0123] The capped polyisocyanate composition may further include components other than the capped polyisocyanate, quaternary ammonium salt, and carbonate diester compound as other components. Examples of other components include, for instance, pigments, dispersants, viscosity modifiers, leveling agents, anti-gelling agents, light stabilizers, antioxidants, UV absorbers, heat resistance improvers, inorganic and organic fillers, plasticizers, lubricants, antistatic agents, reinforcing materials, catalysts, and other additives.

[0124] The capped polyisocyanate composition may also contain alcohol compounds as other components. Details of the alcohol compounds are the same as those described in the above embodiments.

[0125] The capped polyisocyanate composition may also contain solvents as other components. Examples of solvents include benzene, toluene, xylene, cyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, n-butyl acetate, acetic acid cellosolve, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, and 1,4-dioxane. These solvents may be used alone or in combination of two or more. Based on the total mass of the capped polyisocyanate composition, the solvent content may be 0-95% by mass, 5-90% by mass, or 10-80% by mass.

[0126] The capped polyisocyanate composition may contain uncapped polyisocyanates (e.g., polyisocyanates remaining as unreacted material) or unreacted capping agents. Based on the total solids content of the capped polyisocyanate composition, the content of uncapped polyisocyanates in the capped polyisocyanate composition may be less than 5% by mass or 0% by mass. Based on the total solids content of the capped polyisocyanate composition, the content of unreacted capping agents in the capped polyisocyanate composition may be less than 5% by mass or 0% by mass.

[0127] From the perspective of further improving the curing properties of coatings, the effective isocyanate group content (hereinafter referred to as "effective NCO content") of the end-capped polyisocyanate composition can be 4~28% by mass, 5~22% by mass, or 6~16% by mass. Here, the effective NCO content refers to the isocyanate groups present in the end-capped polyisocyanate composition that can participate in the crosslinking reaction, expressed as a percentage by mass. It can also be referred to as the content of free isocyanate groups in the polyisocyanate composition obtained by dissociating the end-capping agent from the end-capped polyisocyanate relative to the total mass of the end-capped polyisocyanate composition (free NCO content). This free NCO content can be determined by reacting the isocyanate groups in the test sample (the polyisocyanate composition obtained by dissociating the end-capping agent from the end-capped polyisocyanate) with an excess of secondary amine, and then back-titrifying the unreacted secondary amine with hydrochloric acid.

[0128] The terminated polyisocyanate composition described above can be prepared by mixing the aforementioned terminated polyisocyanate, the pre-prepared catalyst composition, and other ingredients as needed. The terminated polyisocyanate composition can also be prepared by mixing the terminated polyisocyanate, quaternary ammonium salt, diester compound, and other ingredients as needed. The terminated polyisocyanate composition can be used as a curing agent for, for example, coating compositions (e.g., low-temperature curing coating compositions). That is, another embodiment of this disclosure is a curing agent for coatings (e.g., low-temperature curing coatings) formed from the aforementioned terminated polyisocyanate composition.

[0129] <Coating Composition>

[0130] Another embodiment of this disclosure is a coating composition comprising a main agent and a curing agent, which includes a capped polyisocyanate and the catalyst composition of the above embodiments. This coating composition may contain the above-described capped polyisocyanate composition. The details of the capped polyisocyanate contained in the coating composition are the same as those of the capped polyisocyanate contained in the above-described capped polyisocyanate composition.

[0131] The coating composition described above can be a single-component composition in which all constituent components are contained in a single component, or a multi-component composition in which the constituent components are separately present in multiple components. The multi-component composition may include a first component containing a main agent and a second component containing a curing agent. The terminated polyisocyanate is included in the second component as a curing agent, and the catalyst composition may be included in either the first or the second component. Similarly, when the coating composition includes other components that can be included in the terminated polyisocyanate composition described above, these components may be included in either the first or the second component. When the catalyst composition is included in the second component, the terminated polyisocyanate composition of the above embodiments may serve as the second component.

[0132] Because the above-described coating composition contains a terminated polyisocyanate and the catalyst composition of the above-described embodiments, it exhibits excellent low-temperature curing properties. For the same reason, according to the above-described coating composition, a coating film that does not easily undergo color change and has minimal coloration during the manufacturing process (before and after curing) can be easily formed.

[0133] The main agent contains, for example, a compound containing active hydrogen groups. Examples of active hydrogen groups include hydroxyl groups and amino groups. The average number of functional groups (average number of active hydrogen groups) of the compound containing active hydrogen groups is 2 or more, for example, 2 to 50. Examples of active hydrogen-containing compounds having this average number of functional groups include polyols, polyamines, and amino alcohols. When the main agent contains a polyol as a compound containing active hydrogen groups, it is easy to obtain superior low-temperature curing properties and a coating film with less coloring.

[0134] The number-average molecular weight of compounds containing active hydrogen groups is, for example, 500 to 20,000, or possibly 500 to 10,000. Examples of compounds containing active hydrogen groups with such a number-average molecular weight include polyurethane resins, polyamide resins, saturated or unsaturated polyester resins, alkyd resins modified with saturated or unsaturated fatty acids, acrylic resins, fluororesins, epoxy resins, and cellulose resins (all of which contain active hydrogen groups). From the viewpoint of coating performance such as gloss, fullness, hardness, durability, softness, and drying properties, as well as cost, at least one compound selected from the group consisting of saturated or unsaturated polyester resins, alkyd resins modified with saturated or unsaturated fatty acids, and acrylic resins can be used.

[0135] The mixing ratio of the base agent and the curing agent in the coating composition can be adjusted based on the ratio of the total amount of effective isocyanate groups in the curing agent to the total amount of active hydrogen groups in the base agent. This ratio, expressed as a molar ratio, can be 1 / 9 to 9 / 1 or 2 / 8 to 8 / 2. Better curing properties can be obtained when the molar ratio is within the above range.

[0136] The content of the catalyst composition in the coating composition can be the same as the content of the catalyst composition in the above-mentioned end-capped polyisocyanate composition, and the content of the quaternary ammonium salt can be adjusted in such a way that the content of the quaternary ammonium salt relative to 100 parts by weight of end-capped polyisocyanate is within the above range (e.g., 0.0001 to 40 parts by weight).

[0137] The coating composition can be used as a surface coating and intermediate coating for automobiles, crack-resistant coatings, electrodeposition coatings, coatings for automotive parts, coatings for automotive repair, pre-coated metal / rust-proof steel plates for metal products such as household appliances / office equipment, coatings for building materials, coatings for plastics, adhesives, adhesion promoters, sealants, etc.

[0138] <Coatings and Methods for Coating Formation>

[0139] Another embodiment of this disclosure provides a coating film formed from the coating composition of the above-described embodiments. Additionally, another embodiment of this disclosure provides a method for forming a coating film, comprising the steps of applying the coating composition of the above-described embodiments to a workpiece and curing the coating film (uncured coating film) formed from the coating composition.

[0140] The coating film can be an uncured coating film formed from a mixture of the main agent and the curing agent in the coating composition of the above embodiments, or it can be a coating film formed by curing the uncured coating film (cured coating film). The thickness of the coating film is, for example, 5 to 40 μm. The coating film can be a thin film with a thickness of less than 20 μm.

[0141] The coating composition can be applied using known methods such as roller coating, curtain coating, spraying, electrostatic coating, rotary cup coating, and electrodeposition coating. The coating amount and coating thickness can be appropriately determined based on the material of the surface to be coated.

[0142] The curing of the coating film (uncured coating film) formed by the coating composition can be carried out by heating the coating film. The heating temperature (baking temperature) can be, for example, below 200°C, and the heating time (baking time) can be, for example, 10 to 180 minutes. According to the coating composition of this embodiment, even when baked at a low temperature below 100°C (for example, 60 to 100°C), a cured coating film with good hardness can be formed.

[0143] Examples of materials that can be coated include molded bodies formed from preforms of stainless steel, phosphate-treated steel, zinc steel, iron, copper, aluminum, brass, glass, acrylic polyols, polycarbonate resins, polyethylene terephthalate resins, polyethylene naphthalate resins, polybutylene phthalate resins, polystyrene resins, styrene-acrylonitrile copolymer resins (AS resins), acrylonitrile-butadiene-styrene copolymer resins (ABS resins), polycarbonate-ABS resins, 6-nylon resins, 6,6-nylon resins, MXD6 nylon resins, polyvinyl chloride resins, polyvinyl alcohol resins, polyurethane resins, phenolic resins, melamine resins, polyacetal resins, chlorinated polyolefin resins, polyolefin resins, polyamide resins, polyetheretherketone resins, polyphenylene sulfide resins, NBR resins, chloroprene resins, SBR resins, SEBS resins, etc., as well as surface-treated versions of these molded bodies. Surface-treated versions can be molded bodies of polyethylene, polypropylene, or other olefin resins that have undergone surface treatments such as corona discharge treatment (surface-treated molded bodies).

[0144] Example

[0145] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0146] <Synthesis example 1>

[0147] (Synthesis of quaternary ammonium salts)

[0148] 15.4 g of dimethyl mono-n-octylamine (manufactured by Tokyo Chemical Industry Co., Ltd.), 13.2 g of dimethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd.), and 31.4 g of methanol (manufactured by Kishida Chemical Co., Ltd.) were charged into a 200 ml autoclave and stirred at 110 °C for 12 hours to allow the reaction to proceed. The reaction solution was then transferred to a container (single-necked flask), and the internal pressure of the container was reduced to 30 °C to remove unreacted dimethyl carbonate and methanol, thereby yielding 24.2 g of trimethyl mono-n-octylamine monomethyl carbonate (hereinafter referred to as "TMOA-MC").

[0149] <Synthesis example 2>

[0150] (Synthesis of polyisocyanates)

[0151] In a four-necked flask equipped with a stirrer, thermometer, heating device, nitrogen-sealed tube, and condenser, 995 g of hexamethylene diisocyanate (hereinafter referred to as HDI), 5.0 g of 1,3-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.3 g of phenol (manufactured by Tokyo Chemical Industry Co., Ltd.) were added. The urethane esterification reaction was carried out at 80°C for 2 hours under a nitrogen atmosphere. Then, 0.04 g of potassium 2-ethylhexanoate (manufactured by Tokyo Chemical Industry Co., Ltd.) was added as a catalyst for isocyanurate esterification, and the isocyanurate esterification reaction was carried out at 70°C for 2 hours. After the NCO content reached 40.0% by mass, 0.15 g of JP-508 (manufactured by Johoku Chemical Industry Co., Ltd.) was added to terminate the reaction, and the reaction solution was cooled to room temperature. The reaction solution was subjected to thin-film distillation at 130°C and 0.04 kPa to remove unreacted HDI, yielding purified polyisocyanate (hereinafter referred to as "polyisocyanate A-1"). Polyisocyanate A-1 has an NCO content of 21.8% by mass and a viscosity of approximately 2500 mPa·s at 25°C.

[0152] ( 1 H-NMR: Determination of isocyanurate group content)

[0153] Perform polyisocyanate A-1 1 The isocyanurate group content (the content of isocyanurate groups relative to the total of isocyanurate and urethane groups (100 mol%)) was determined by ¹H-NMR determination. Specifically, the isocyanurate group content was calculated from the area of ​​the hydrogen atom signal of the methylene group adjacent to the nitrogen atom of the isocyanurate group at around 3.7 ppm and the area of ​​the hydrogen atom signal of the nitrogen atom of the urethane group at around 8.5 ppm. The isocyanurate group content was 89 mol%. It should be noted that... 1 The H-NMR measurements were performed under the following conditions.

[0154] [Measurement Conditions]

[0155] (1) Measuring device: ECX400M (manufactured by Nippon Electronics Corporation, Japan) 1 H-NMR)

[0156] (2) Measurement temperature: 23℃

[0157] (3) Sample concentration: 0.1 g / 1 ml

[0158] (4) Total number of times: 16

[0159] (5) Relaxation time: 5 seconds

[0160] (6) Solvent: Deuterated dimethyl sulfoxide

[0161] (7) Chemical shift reference: hydrogen atom signal of methyl group in deuterated dimethyl sulfoxide (2.5 ppm)

[0162] <Examples 1-8 and Comparative Example 1>

[0163] (Modification of the catalyst composition)

[0164] Dimethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd., "DMC" in the table), which is a carbonate diester compound, and TMOA-MC, which is a quaternary ammonium salt, were mixed in the mass ratio [a / b] (quaternary ammonium salt / carbonate diester compound) shown in Table 1 below to prepare the catalyst compositions of Examples 1 to 8 (catalyst compositions 1 to 8). It should be noted that in Comparative Example 1, the carbonate diester compound was not used, and TMOA-MC was used directly as the catalyst.

[0165] (Evaluation of colorfastness)

[0166] Catalyst compositions 1-8 were stored at 80°C for 48 hours. Using a COH7700 spectrophotometer manufactured by Nippon Denshoku Kogyo Co., Ltd., the b* values ​​of the catalyst compositions in the CIE Lab standard were measured before and after storage. The "rate of change of b* value" was calculated from the b* values ​​before and after storage (initial b* value and b* value after storage) using the following formula. This rate of change was used as a benchmark to evaluate the catalyst compositions' resistance to discoloration over time (discoloration resistance). Similarly, the discoloration resistance of the catalyst (TMOA-MC) of Comparative Example 1 was also evaluated.

[0167] Rate of change of b* value (unit: %) = 100 × (b* value after saving - initial b* value) / initial b* value

[0168] The evaluation criteria are shown below, and the results are presented in Table 1. If the evaluation is B, the catalyst composition is considered to have sufficient resistance to discoloration.

[0169] A: The rate of change of the b* value is greater than 0% and less than 30%.

[0170] B: The rate of change of the b* value is greater than 30% and less than 60%.

[0171] C: The rate of change of b* value is over 60%.

[0172] (Preparation of capped polyisocyanate compositions)

[0173] Using catalyst compositions 1-8 and the catalyst of Comparative Example 1 respectively, the end-capped polyisocyanate compositions (end-capped polyisocyanate compositions 1-9) of Examples 1-8 and Comparative Example 1 were prepared by the following method.

[0174] In a four-necked flask equipped with a stirrer, thermometer, heating device, nitrogen-sealed tube, and condenser, 515 g of polyisocyanate A-1 and 250 g of butyl acetate were added. After stirring for 30 minutes, 234 g of methyl ethyl ketone oxime (manufactured by Ube Industries, Ltd., listed as "MEKO") (equivalent ratio to the mixed amount of polyisocyanate A-1 was 1.0) was added in three portions, ensuring the temperature did not exceed 80°C. The reaction was then carried out at 70°C for 2 hours. In the infrared absorption spectrum (IR measurement), the peak of the NCO group (2270 cm⁻¹) was observed. -1 When the quaternary ammonium salt disappears (nearby), cool to room temperature, and add catalyst compositions 1-8 or the catalyst of Comparative Example 1 in such a way that the amount of quaternary ammonium salt added is 22.5 g, and stir for 30 minutes. Through the above operation, end-capped polyisocyanate compositions 1-9 are obtained respectively.

[0175] (Preparation of coating composition)

[0176] Paint compositions (paint compositions 1-9) of Examples 1-8 and Comparative Example 1 were prepared using end-capped polyisocyanate compositions 1-9, respectively. Specifically, the paint compositions were prepared by mixing ACRYDIC A-801 (manufactured by DIC Corporation, acrylic polyol, solid content concentration 50% by mass, hydroxyl value 50 mg KOH / g, trade name "A801" in the table) as the main agent, the end-capped polyisocyanate composition ("BPI" in the table) as the curing agent, and butyl acetate (manufactured by Kishida Chemical Co., Ltd., "BtAc" in the table). The mixing amounts of each component are shown in Table 1.

[0177] (Coating manufacturing and color evaluation)

[0178] Under the following conditions, coating compositions 1 to 9 were applied to the substrate and allowed to cure, resulting in coatings (cured coatings) as in Examples 1 to 8 and Comparative Example 1, respectively. The b* value of the cured coating in the CIE Lab standard was measured using a colorimeter (product name: SPECTRO2GUIDE) manufactured by BYK-GARDNER. The results are shown in Table 1. It should be noted that a colored steel sheet (white) (manufactured by Yutaka Panel Service, 0.8 mm thick) was used as the substrate.

[0179] [condition]

[0180] • Painting method: Use an applicator

[0181] Humidity conditions: 50%RH

[0182] Temperature conditions: 23℃

[0183] • Drying (curing) conditions: Forced drying at 160℃ for 1 hour

[0184] • Film thickness: Approximately 20 μm

[0185] (Evaluation of low-temperature curing properties: Measurement of coating hardness)

[0186] Under the following conditions, coating compositions 1 to 9 were applied to a substrate and allowed to cure, resulting in coatings (cured coatings) of Examples 1 to 8 and Comparative Example 1, respectively. The substrate used was a white colored steel sheet (manufactured by Yutaka Panel Service Co., Ltd., 0.8 mm thick).

[0187] [condition]

[0188] • Painting method: Use an applicator

[0189] Humidity conditions: 50%RH

[0190] Temperature conditions: 23℃

[0191] • Drying (curing) conditions: Forced drying at 80℃ for 20 minutes

[0192] • Film thickness: Approximately 20 μm

[0193] The hardness of the coating (cured coating) obtained above was determined under the following conditions according to ISO 14577. The results are shown in Table 1.

[0194] [condition]

[0195] • Test setup: Fischerscope HM2000 (manufactured by Fischer Instruments)

[0196] Indenter: Vickers hardness diamond

[0197] • Test load: 5mN

[0198] • Test temperature: 25℃

[0199] <Example 9>

[0200] (Preparation of capped polyisocyanate compositions)

[0201] In a four-necked flask equipped with a stirrer, thermometer, heating device, nitrogen sealing tube, and condenser, 500g of polyisocyanate A-1 and 250g of butyl acetate were added. After stirring for 30 minutes, 249g of 3,5-dimethylpyrazole (manufactured by Tokyo Chemical Industry Co., Ltd., listed as "DMP" in the table) (with an equivalent ratio of 1.0 to the mixed amount of polyisocyanate A-1) was added in three portions, ensuring the temperature did not exceed 80°C. The reaction was then carried out at 70°C for 2 hours. In the infrared absorption spectrum (IR measurement), the peak of the NCO group (2270 cm⁻¹) was observed. -1 When the concentration of quaternary ammonium salt (near) disappears, cool to room temperature, and add 22.5 g of the catalyst composition of Example 4 (catalyst composition 4) in such a way that the amount of quaternary ammonium salt added is 22.5 g, and stir for 30 minutes. Through the above operation, the end-capped polyisocyanate composition 10 is obtained.

[0202] (Preparation of coating compositions, fabrication and evaluation of coating films)

[0203] The coating composition 10 was prepared in the same manner as in Example 1, except that the formulation amounts of each component were adjusted to those described in Table 1, and the coating composition 10 was used instead of the coating composition 10. Furthermore, a coating film (cured coating film) was manufactured in the same manner as in Example 1, except that the color evaluation (b* determination) and hardness determination of the coating film were performed. The results are shown in Table 1.

[0204] <Example 10>

[0205] The catalyst composition 11 was prepared in the same manner as in Example 2, except that a 10% by mass methanol solution of tetramethylammonium hydroxide (hereinafter referred to as "TMA-OH") (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of TMOA-MC, and the mixing mass ratio of each component "quaternary ammonium salt (TMA-OH) / diesel carbonate compound (DMC) / alcohol compound (methanol)" (mass ratio [a / b / c] in the table) was adjusted to 1 / 0.5 / 9. The colorfastness of the catalyst composition 11 was evaluated. The results are shown in Table 2.

[0206] Catalyst composition 11 was used instead of catalyst composition 1, and the preparation of the end-capped polyisocyanate composition 11 was carried out in the same manner as in Example 1. The mixing amounts of each component were adjusted as described in Table 2. The coating composition 11 was then prepared in the same manner as in Example 1. Furthermore, coating composition 11 was used instead of coating composition 1, and the preparation of a coating film was carried out in the same manner as in Example 1. The color evaluation and hardness determination of the coating film were then performed. The results are shown in Table 2.

[0207] <Examples 11-12>

[0208] Catalyst compositions 12-13 were prepared in the same manner as in Example 10, except that diethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd., "DEC" in the table) or diethyl carbonate (manufactured by Tokyo Chemical Industry Co., Ltd., "EC" in the table) were used instead of dimethyl carbonate, and the colorfastness of catalyst compositions 12-13 was evaluated. The results are shown in Table 2.

[0209] Catalyst compositions 12-13 were used instead of catalyst composition 1, and the preparation of end-capped polyisocyanate compositions 12-13 was carried out in the same manner as in Example 1. The mixing amounts of each component were adjusted as described in Table 2. Coating compositions 12-13 were then prepared in the same manner as in Example 1. Furthermore, coating films were manufactured using coating compositions 12-13 instead of coating composition 1, and the color evaluation and hardness determination of the coating films were performed. The results are shown in Table 2.

[0210] <Example 13>

[0211] In addition to TMOA-MC and DMC, methanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was also mixed in, and the mixing mass ratio of each component "quaternary ammonium salt (TMA-OH) / diesel carbonate compound (DMC) / alcohol compound (methanol)" (mass ratio [a / b / c] in the table) was adjusted to 1 / 0.5 / 9. Otherwise, the catalyst composition 14 was prepared in the same manner as in Example 1, and the colorfastness of the catalyst composition 14 was evaluated. The results are shown in Table 2.

[0212] Catalyst composition 14 was used instead of catalyst composition 1, and the preparation of the end-capped polyisocyanate composition 14 was carried out in the same manner as in Example 1. The mixing amounts of each component were adjusted as described in Table 2. The coating composition 14 was then prepared in the same manner as in Example 1. Furthermore, coating composition 14 was used instead of coating composition 1, and the preparation of a coating film was carried out in the same manner as in Example 1. The color evaluation and hardness determination of the coating film were then performed. The results are shown in Table 2.

[0213] <Example 14>

[0214] The mass ratio of the components in the catalyst composition “quaternary ammonium salt (TMA-OH) / diesel carbonate compound (DMC) / alcohol compound (methanol)” (mass ratio [a / b / c] in the table) was adjusted to 1 / 0.5 / 18. Otherwise, the same procedure as in Example 13 was followed to prepare catalyst composition 15, and the discoloration resistance of catalyst composition 15 was evaluated. The results are shown in Table 2.

[0215] Catalyst composition 15 was used instead of catalyst composition 1, and the preparation of the end-capped polyisocyanate composition 15 was carried out in the same manner as in Example 1. The mixing amounts of each component were adjusted as described in Table 2. The coating composition 15 was then prepared in the same manner as in Example 1. Furthermore, coating composition 15 was used instead of coating composition 1, and the preparation of a coating film was carried out in the same manner as in Example 1. The color evaluation and hardness determination of the coating film were then performed. The results are shown in Table 2.

[0216] <Comparative Example 2>

[0217] Using TMA-OH directly as a catalyst, the end-capped polyisocyanate composition 16 was prepared in the same manner as in Comparative Example 1, except that end-capped polyisocyanate composition 16 was used instead of end-capped polyisocyanate composition 1, and the mixing amounts of each component were adjusted as described in Table 2. The coating composition 16 was prepared in the same manner as in Example 1. Furthermore, coating composition 16 was used instead of coating composition 1, and a coating film was manufactured in the same manner as in Example 1. The hardness of the coating film was measured. The results are shown in Table 2.

[0218] [Table 1]

[0219]

[0220] [Table 2]

[0221]

Claims

1. A catalyst composition, which is a catalyst composition for dissociating a blocking agent from a blocked polyisocyanate, containing a quaternary ammonium salt and a carbonic acid diester compound.

2. The catalyst composition of claim 1, wherein, The content ratio of the carbonic acid diester compound to the quaternary ammonium salt is 0.05 to 50 in terms of mass ratio.

3. The catalyst composition of claim 1, wherein, The quaternary ammonium salt contains a quaternary ammonium cation represented by the following formula (1), In formula (1), R 1 represents an alkyl group having 1 to 16 carbons optionally having a hydroxyl group, an amino group, or an alkoxy group as a substituent, R 2 ~R 4 each independently represents an alkyl group having 1 to 8 carbons.

4. The catalyst composition of claim 1, wherein, The carbonic acid diester compound contains a compound represented by the following formula (2), In formula (2), R 5 and R 6 each independently represents an aliphatic saturated hydrocarbon group having a carbon number of 1 to 16, R 5 and R 6 are optionally linked to each other to form a ring.

5. The catalyst composition according to claim 1, further containing an alcohol compound.

6. A blocked polyisocyanate composition comprising a blocked polyisocyanate and the catalyst composition according to any one of claims 1 to 5.

7. The blocked polyisocyanate composition of claim 6, wherein, The content of the quaternary ammonium salt is 0.0001 to 40 parts by mass relative to 100 parts by mass of the blocked polyisocyanate.

8. The blocked polyisocyanate composition of claim 6, wherein, The blocked polyisocyanate contains a structure derived from an aliphatic polyisocyanate having a carbon number of 4 to 6 or a derivative thereof.

9. The blocked polyisocyanate composition of claim 6, wherein, The blocked polyisocyanate has at least one group selected from the group consisting of an isocyanate group blocked with an oxime-based blocking agent and an isocyanate group blocked with a pyrazole-based blocking agent.

10. A coating composition, which is a coating composition comprising a main agent and a curing agent, The curing agent contains a blocked polyisocyanate, The main agent or the curing agent contains the catalyst composition according to any one of claims 1 to 5.

11. A coated film formed from the coating composition according to claim 10.

12. A method for forming a coated film, comprising a step of applying the coating composition according to claim 10 to an object to be coated, heating at 60 to 100°C, and curing a coated film formed from the coating composition.

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