CATALYST COMPOSITION, BLOCKED POLYISOCYANATE COMPOSITION, COATING ... FILM, AND METHOD FOR FORMING COATING FILM

Abstract

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

Description

[Technical field]

[0001] The present disclosure relates to a catalyst composition, a blocked polyisocyanate composition, a coating composition, a coating film, and a method for forming a coating film. [Background technology]

[0002] Polyisocyanates have been known as curing agents used in paints, etc. For example, polyurethane resin paints that combine polyols and polyisocyanates are known to have very good abrasion resistance, chemical resistance, and stain resistance.

[0003] Paints using polyisocyanate as a curing agent are generally two-liquid compositions, in which the base agent (e.g., polyol) and polyisocyanate are stored separately and mixed when used for painting. However, once mixed, the paint hardens in a short time, so the pot life is short, and there are problems with workability when painting. In addition, since polyisocyanate easily reacts with water, it was impossible to use the above-mentioned paint in water-based paints such as electrodeposition paints.

[0004] As a method for dealing with these problems, a method is known in which polyisocyanate is inactivated by reacting it with a blocking agent. The blocked polyisocyanate obtained by this method does not react with the base agent (polyol, etc.) at room temperature, but when heated, the blocking agent dissociates, regenerating the isocyanate group, which then reacts with the base agent to form a crosslink. Therefore, according to the above method, the pot life is not limited, and it is possible to mix the base agent and the curing agent in advance to form a paint, and it is also possible to apply polyisocyanate to water-based paints.

[0005] As a catalyst for dissociating a blocking agent from a blocked polyisocyanate (blocking agent dissociation catalyst), for example, a quaternary ammonium salt is known (see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 08-170048 Summary of the Invention [Problem to be solved by the invention]

[0007] The above-mentioned quaternary ammonium salt can impart low-temperature curing properties to a coating composition containing a blocked polyisocyanate. On the other hand, the quaternary ammonium salt is prone to color change (e.g., yellowing) over time, and the quaternary ammonium salt after color change may cause coloring of the coating film. The above-mentioned Patent Document 1 describes that a cured resin using a specific quaternary ammonium salt has excellent yellowing resistance compared to a cured resin using an organometallic catalyst, but does not describe the color change of the quaternary ammonium salt over time.

[0008] Therefore, one aspect of the present disclosure has an object to provide a catalyst composition that is not only capable of imparting low-temperature curing properties to a coating composition containing a blocked polyisocyanate, but also is less likely to undergo color change over time. [Means for solving the problem]

[0009] As a result of the investigations by the inventors of the present disclosure, it was surprisingly found that in a mixture of a quaternary ammonium salt and a carbonic acid diester compound, the color change of the quaternary ammonium salt over time is suppressed. The present disclosure has been made based on the findings of the inventors.

[0010] The present disclosure provides at least the following [1] to

[12] .

[0011] [1] A catalyst composition for use in dissociating a blocking agent from a blocked polyisocyanate, comprising: A catalyst composition comprising a quaternary ammonium salt and a carbonate diester compound.

[0012] [2] The catalyst composition according to [1], wherein a ratio of the content of the carbonate diester compound to the content of the quaternary ammonium salt is 0.05 to 50 in terms of mass ratio.

[0013] [3] The catalyst composition according to [1] or [2], wherein the quaternary ammonium salt contains a quaternary ammonium cation represented by the following formula (1): [ka] [In formula (1), R 1 represents an alkyl group having 1 to 16 carbon atoms which may have a hydroxy 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 carbon atoms.]

[0014] [4] The catalyst composition according to any one of [1] to [3], wherein the carbonate diester compound comprises a compound represented by the following formula (2): [ka] [In formula (2), R 5 and R 6 each independently represents an aliphatic saturated hydrocarbon group having 1 to 16 carbon atoms; R 5 and R 6 may be linked to each other to form a ring.

[0015] [5] The catalyst composition according to any one of [1] to [4], further comprising an alcohol compound.

[0016] [6] A blocked polyisocyanate composition comprising a blocked polyisocyanate and the catalyst composition according to any one of [1] to [5].

[0017] [7] The blocked polyisocyanate composition according to [6], wherein the content of the quaternary ammonium salt is 0.0001 to 40 parts by mass based on 100 parts by mass of the blocked polyisocyanate.

[0018] [8] The blocked polyisocyanate composition according to [6] or [7], wherein the blocked polyisocyanate contains a structure derived from an aliphatic polyisocyanate having 4 to 6 carbon atoms or a derivative thereof.

[0019] [9] The blocked polyisocyanate composition according to any one of [6] to [8], 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.

[0020]

[10] A coating composition comprising a base agent and a curing agent, The curing agent contains a blocked polyisocyanate, and the base agent or the curing agent contains the catalyst composition according to any one of [1] to [5], or A coating composition, wherein the curing agent comprises the blocked polyisocyanate composition according to any one of [6] to [9].

[0021]

[11] A coating film formed from the coating composition according to

[10] .

[0022]

[12] A method for forming a coating film, comprising the steps of applying the coating composition according to

[10] to a substrate and heating the substrate at 60 to 100°C to cure the coating film made of the coating composition. Effect of the Invention

[0023] According to one aspect of the present disclosure, it is possible to provide a catalyst composition that not only can impart low-temperature curing properties to a coating composition containing a blocked polyisocyanate, but also is less likely to undergo color change over time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, exemplary embodiments of the present disclosure will be described. However, the present disclosure is not limited to the following embodiments. In this specification, a numerical range indicated using "~" indicates a range including the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In addition, unless specifically stated otherwise, the units of the numerical values ​​before and after "~" are the same. In addition, the upper limit and lower limit values ​​individually stated can be combined in any combination.

[0025] <Catalyst composition> One embodiment of the present disclosure is a catalyst composition containing a quaternary ammonium salt and a carbonic acid diester compound, which is used to dissociate a blocking agent from a blocked polyisocyanate.

[0026] The catalyst composition can impart low-temperature curing properties to a coating composition containing a blocked polyisocyanate. Furthermore, the catalyst composition is less likely to cause color change (e.g., yellowing) over time, and can contribute to reducing color change during the preparation of a coating film (before and after the coating film is cured). Therefore, the catalyst composition can easily form a coating film with little coloring.

[0027] (Quaternary ammonium salts) The quaternary ammonium salt contains a quaternary ammonium cation as a cationic group. As the quaternary ammonium salt, a compound known as a blocking agent dissociation catalyst can be used.

[0028] The quaternary ammonium cation is represented, for example, by the following formula (1). [ka]

[0029] In formula (1), R 1 ~R 4 R each independently represents a hydrocarbon group. 1 ~R4 may be the same or different from each other.

[0030] The hydrocarbon group may be an aliphatic hydrocarbon group (e.g., an alkyl group or a cycloalkyl group) or an aromatic hydrocarbon group (e.g., an aryl group). From the viewpoint of enhancing the effect of improving low-temperature curing properties and enhancing the effect of reducing color change over time and coloring of the coating film, the hydrocarbon group may be an aliphatic hydrocarbon group. In particular, when the aliphatic hydrocarbon group is an alkyl group, the above effects tend to be enhanced.

[0031] When the hydrocarbon group is an aliphatic hydrocarbon group, the number of carbon atoms is, for example, 1 to 16. The number of carbon atoms in the aliphatic hydrocarbon group may be 3 or more or 6 or more, and 12 or less or 8 or less. When the hydrocarbon group is an aromatic hydrocarbon group, the number of carbon atoms is, for example, 6 to 16. The number of carbon atoms in the aromatic hydrocarbon group may be 8 or more or 10 or more, and 14 or less or 12 or less.

[0032] The hydrocarbon group may have a substituent. Examples of the substituent include a hydroxy group, an amino group, and an alkoxy group. The number of carbon atoms in the alkoxy group may be, for example, 1 to 8, 1 to 6, 1 to 4, or 1 to 2. Examples of the alkoxy group include a methoxy group, an ethoxy group, a butoxy group, a propyloxy group, a pentyloxy group, and a hexyloxy group. The number of the substituent may be, for example, 0 to 3. The number of carbon atoms in the substituent is included in the number of carbon atoms in the hydrocarbon group.

[0033] In one embodiment, R in formula (1) 1 represents an alkyl group having 1 to 16 carbon atoms which may have a hydroxy 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 carbon atoms. When such a quaternary ammonium salt is used, a coating composition having excellent low-temperature curing properties is likely to be obtained.

[0034] R 1Specific examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, a 2-propylheptyl group, a nonyl group, a decyl group, an isodecyl group, a dodecyl group, a hexadecyl group, etc. These groups may be substituted with one or more substituents (for example, a hydroxy group, an amino group, or an alkoxy group).

[0035] From the viewpoint of making it easier to obtain a coating composition with even better low-temperature curing properties, R 1 may be an unsubstituted alkyl group or hydroxyalkyl group having 1 to 16 carbon atoms. 1 When the alkyl group having 1 to 16 carbon atoms is an unsubstituted alkyl group having 1 to 16 carbon atoms, the effect of improving low-temperature curing tends to be enhanced. From the viewpoint of further enhancing this effect, the unsubstituted alkyl group having 1 to 16 carbon atoms is preferably an alkyl group having 1 to 10 carbon atoms. When the unsubstituted alkyl group having 1 to 16 carbon atoms is an alkyl group having 1 to 4 carbon atoms, the above effect becomes more remarkable. On the other hand, when the unsubstituted 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 film tends to be enhanced. This tendency is remarkable when the alkyl group is an alkyl group having 6 to 8 carbon atoms (particularly an n-octyl group).

[0036] R 2 ~R 4 Specific examples of the alkyl group represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, and a 2-ethylhexyl group.

[0037] From the viewpoint of making it easier to obtain a coating composition with even better low-temperature curing properties, R 2 ~R 4may be an alkyl group having 1 to 4 carbon atoms. From the viewpoint of further enhancing the effect of improving low temperature curing property, the alkyl group having 1 to 4 carbon atoms is preferably an alkyl group having 1 to 2 carbon atoms, and more preferably a methyl group.

[0038] In view of the above, the quaternary ammonium cation is represented by R 1 is an alkyl group having 1 to 10 carbon atoms, and R 2 ~R 4 may be a cation in which the alkyl group has 1 to 4 carbon atoms. Specific examples of suitable cations include trimethylmono-n-octylammonium cation, trimethylmono-n-butylammonium cation, tetramethylammonium cation, and tetrabutylammonium cation, and among these, the trimethylmono-n-octylammonium cation is preferred.

[0039] The anion group of the quaternary ammonium salt may be a group consisting of an anion derived from an acid such as an organic acid or an inorganic acid, or may be a group consisting of an anion derived from an ester such as a carbonate ester. The anion group of the quaternary ammonium salt may be a group that does not fall into any of these categories (for example, a hydroxyl group (hydroxide ion)).

[0040] Examples of groups (organic acid groups) consisting of anions derived from organic acids include fatty acid groups. The number of carbon atoms in the fatty acid group (aliphatic monocarboxylic acid group) may be, for example, 1 to 12, or 1 to 7 or 1 to 3. Specific examples of the fatty acid group include a formic acid group, an acetic acid group, a 2-ethylhexanoic acid group (octylic acid group), a lauric acid group, a cyclohexanecarboxylic acid group, and a pivalic acid group.

[0041] Examples of groups consisting of anions derived from inorganic acids (inorganic acid groups) include halogen groups (fluoro, chloro, bromo, etc.), hydrogen carbonate groups, and carbonate groups.

[0042] An example of a group consisting of an anion derived from an ester (ester group) is a monoalkyl carbonate group. The number of carbon atoms in the alkyl group in the monoalkyl carbonate group may be, for example, 1 to 8, or 1 to 4 or 1 to 2. Specific examples of the monoalkyl carbonate group include a methyl carbonate group, an ethyl carbonate group, a propyl carbonate group, and a butyl carbonate group.

[0043] The anion group of the quaternary ammonium salt may be a fatty acid group having 1 to 12 carbon atoms, a monoalkyl carbonate group having an alkyl group having 1 to 8 carbon atoms, or a hydroxyl group, from the viewpoint of easily obtaining a coating composition having excellent low-temperature curing properties. The anion group may be a fatty acid group having 1 to 7 carbon atoms or a monoalkyl carbonate group having an alkyl group having 1 to 4 carbon atoms, from the viewpoint of further enhancing the effect of improving low-temperature curing properties, and may be a monoalkyl carbonate group having an alkyl group having 1 to 2 carbon atoms, from the viewpoint of further enhancing said effect.

[0044] In view of the above, the quaternary ammonium salt is a quaternary ammonium cation represented by the above formula (1), 1 represents an alkyl group having 1 to 16 carbon atoms which may have a hydroxy group, an amino group or an alkoxy group as a substituent; R 2 ~R 4 may be a combination of a quaternary ammonium cation, each of which independently represents an alkyl group having 1 to 8 carbon atoms, and a fatty acid group having 1 to 12 carbon atoms, a monoalkyl carbonate group having an alkyl group having 1 to 8 carbon atoms, or a hydroxyl group. 1 is an alkyl group having 1 to 10 carbon atoms, and R 2 ~R 4 is a C1-4 alkyl group, and a monoalkyl carbonate group or hydroxyl group having an alkyl group having a C1-8 carbon atom are preferred. 1 is an alkyl group having 4 to 8 carbon atoms, and R 2 ~R 4 A combination of a cation which is an alkyl group having 1 to 2 carbon atoms and a monoalkylcarbonate group having an alkyl group having 1 to 8 carbon atoms is more preferable.

[0045] Specific examples of quaternary ammonium salts include trimethyl mono n-octyl ammonium hydrogen carbonate, trimethyl mono n-octyl ammonium methyl carbonate, trimethyl mono n-octyl ammonium carbonate, trimethyl mono n-butyl ammonium methyl carbonate, trimethyl mono n-butyl ammonium acetate, tetramethyl ammonium acetate, hexadecyl trimethyl ammonium hydroxide, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide, tetrabutyl ammonium hydroxide, trimethyl (2-hydroxypropyl) ammonium 2-ethyl hexanoate, tetramethyl ammonium hydrogen carbonate, tetraethyl ammonium hydrogen carbonate, tetra-n-propyl ammonium hydroxide, tetramethyl ... Examples of the hydrogen carbonate salt include ammonium hydrogen carbonate, tetra-n-butylammonium hydrogen carbonate, triethyl monomethyl ammonium hydrogen carbonate, tri-n-propyl monomethyl ammonium hydrogen carbonate, tri-n-butyl monomethyl ammonium hydrogen carbonate, tri-n-butyl monoethyl ammonium hydrogen carbonate, tetramethyl ammonium monomethyl carbonate, tetraethyl ammonium monoethyl carbonate, tetra-n-butyl ammonium monobutyl carbonate, triethyl monomethyl ammonium monomethyl carbonate, tri-n-propyl monomethyl ammonium monomethyl carbonate, tri-n-butyl monomethyl ammonium monomethyl carbonate, tri-n-butyl monoethyl ammonium monoethyl carbonate, tetramethyl ammonium carbonate, and tetra-n-butyl ammonium carbonate.

[0046] The catalyst composition may contain one or more types of quaternary ammonium salt.

[0047] The content of the quaternary ammonium salt may be 1% by mass or more, 5% by mass or more, 10% by mass or more, 20% by mass or more, or 30% by mass or more, based on the total mass of the catalyst composition, from the viewpoint of easily obtaining a coating composition having excellent low-temperature curing properties. The content of the quaternary ammonium salt may be 99% by mass or less, 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, based on the total mass of the catalyst composition, from the viewpoint of further reducing color change over time and coloring of the coating film. From these viewpoints, the content of the quaternary ammonium salt may be, for example, 1 to 99% by mass, 5 to 99% by mass, 10 to 99% by mass, 20 to 95% by mass, 30 to 90% by mass, 1 to 60% by mass, 1 to 40% by mass, 1 to 20% by mass, or 1 to 10% by mass, based on the total mass of the catalyst composition.

[0048] (carbonate diester compound) The carbonate diester compound is, for example, a compound represented by the following formula (2). [ka]

[0049] In formula (2), R 5 and R 6 each independently represents a hydrocarbon group; R 5 and R 6 may be linked together to form a ring. 5 and R 6 may be the same or different from each other.

[0050] The hydrocarbon group may be an aliphatic hydrocarbon group (e.g., an alkyl group, an alkylene group, a cycloalkyl group, or a cycloalkylene group), or an aromatic hydrocarbon group (e.g., an aryl group or an arylene group). In particular, when the hydrocarbon group is an aliphatic hydrocarbon group, the effect of reducing color change over time and coloring of the coating film tends to be enhanced. From the viewpoint of further enhancing this effect, the hydrocarbon group may be an aliphatic saturated hydrocarbon group.

[0051] When the hydrocarbon group is an aliphatic hydrocarbon group, the number of carbon atoms is, for example, 1 to 16. The number of carbon atoms in the aliphatic hydrocarbon group may be 1 or more or 2 or more, and may be 12 or less or 8 or less. When the hydrocarbon group is an aromatic hydrocarbon group, the number of carbon atoms is, for example, 6 to 16. The number of carbon atoms in the aromatic hydrocarbon group may be 8 or more or 10 or more, and may be 14 or less or 12 or less.

[0052] The hydrocarbon group may have a substituent. Examples of the substituent include a hydroxy group, an amino group, and an alkoxy group. The number of carbon atoms in the alkoxy group may be, for example, 1 to 8, 1 to 6, 1 to 4, or 1 to 2. Examples of the alkoxy group include a methoxy group, an ethoxy group, a butoxy group, a propyloxy group, a pentyloxy group, and a hexyloxy group. The number of the substituent may be, for example, 0 to 3.

[0053] In one embodiment, R in formula (2) 5 and R 6 are each independently an aliphatic saturated hydrocarbon group having a carbon number of 1 to 16. When such a carbonic acid diester compound is used, the color change over time and the coloring of the coating film can be further reduced.

[0054] R 5 and R 6 The aliphatic saturated hydrocarbon group may be an alkyl group. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a s-butyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, a 2-propylheptyl group, a nonyl group, a decyl group, an isodecyl group, a dodecyl group, and a hexadecyl group.

[0055] R 5 and R 6 The aliphatic saturated hydrocarbon groups may be linked to each other to form an alkylene group. 5 and R 6Specific examples of the alkylene group formed by linking together include an ethylene group, a 1,2-propylene group, a 1,2-butylene group, and a 2,3-butylene group.

[0056] From the viewpoint of improving the effect of reducing color change over time and coloring of the coating film, R 5 and R 6 may each independently be an alkyl group having 1 to 4 carbon atoms (such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, an s-butyl group, or a t-butyl group). 5 and R 6 is an alkyl group having 1 to 2 carbon atoms (methyl group or ethyl group), the tendency is higher. 5 and R 6 The tendency is even higher when the group is a methyl group.

[0057] Specific examples of the carbonate diester compound 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, butylene carbonate, 2,3-butylene carbonate, and diphenyl carbonate.

[0058] The catalyst composition may contain one or more types of carbonate diester compounds.

[0059] The ratio of the content of the carbonic acid diester compound to the content of the quaternary ammonium salt (the content of the carbonic acid diester compound / the content of the quaternary ammonium salt) may be 0.05 to 50 in mass ratio. When the ratio is 0.05 or more, the coloring of the coating film tends to be further reduced, and when the ratio is 50 or less, a coating composition having excellent low-temperature curing properties is easily obtained. From these viewpoints, the ratio may be 0.1 or more, 0.3 or more, 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, or 10 or more, and may be 40 or less, 30 or less, 20 or less, 10 or less, 6 or less, 5.5 or less, or 5 or less, and may 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. The quaternary ammonium cation represented by the above formula (1), wherein R in formula (1) 1 is an alkyl group having 4 to 8 carbon atoms, and R 2 ~R 4 is an alkyl cation having 1 to 4 carbon atoms (e.g., trimethylmono n-octylammonium cation or trimethylmono n-butylammonium cation) and a monoalkylcarbonate group having an alkyl group having 1 to 8 carbon atoms. Salt When used, if the above ratio is 4 or more, the effect of reducing color change over time and coloring of the coating film tends to be enhanced.

[0060] (Other ingredients) The catalyst composition may further contain components other than the quaternary ammonium salt and the carbonic acid diester compound. Examples of such components include alcohol compounds. The use of alcohol compounds tends to enhance the effect of suppressing the color change of the quaternary ammonium salt, the effect of reducing the coloring of the coating film, and the effect of improving low-temperature curing. The reason why such effects are obtained is not clear, but it is speculated that the alcohol compound functions as a solvent in the catalyst composition, dissolving the quaternary ammonium salt and the carbonic acid diester compound, which makes it easier for the carbonic acid diester compound to act on the quaternary ammonium salt, and the dissolution of the quaternary ammonium salt and the carbonic acid diester compound improves the uniformity of the reaction system and enhances the catalytic activity.

[0061] The alcohol compound may be a monoalcohol (a compound having one hydroxyl group) or a polyol (a compound having two or more hydroxyl groups). When a monoalcohol is used as the alcohol compound, the effect of improving low-temperature curing and the effect of reducing coloring of the coating film tend to be more pronounced.

[0062] The molecular weight of the alcohol compound may be, for example, from 18 to 1000, from 18 to 700, or from 18 to 500. When the molecular weight of the alcohol compound is 500 or less, the effect of improving low-temperature curing properties and the effect of reducing coloration of the coating film tend to be enhanced.

[0063] The alcohol compound may be an aliphatic alcohol from the viewpoint of further reducing coloration of the catalyst composition and the coating film. The aliphatic alcohol may be linear or branched. The number of carbon atoms in the aliphatic alcohol may be 1 to 30, 1 to 10, 1 to 6, or 1 to 4.

[0064] Specific examples of alcohol compounds include methanol, ethanol, propanol, butanol, pentanol, hexanol, octanol, 2-ethylhexanol, 3,3,5-trimethyl-1-hexanol, n-tridecanol, 2-tridecanol, 2-octyldodecanol, pentadecanol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol, cyclohexanemethanol, heneicosanol, ceryl alcohol, ethylene glycol, 1,2-propanediol, 1,3-butanediol, and 1,4-butanediol. , 1,5-propanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, neopentyl glycol, 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-ethylene glycol, 2-n-eicosane-1,2-ethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, pentaerythritol, etc. Among them, when methanol is used, the effect of improving low-temperature curing and the effect of reducing coloring of the coating film tend to be more enhanced.

[0065] The catalyst composition may contain one or more types of alcohol compounds.

[0066] The ratio of the content of the alcohol compound to the content of the quaternary ammonium salt (content of the alcohol compound / content of the quaternary ammonium salt) may be 0.05 to 50 by mass. When the ratio is 0.05 to 50, a coating composition having excellent low-temperature curing properties is easily obtained, and color change over time and coloring of the coating film tend to be further reduced. From the viewpoint of obtaining such effects more significantly, the ratio may be 0.1 or more, 1 or more, 5 or more, or 10 or more, and may be 40 or less, 30 or less, or 20 or less, or may be 0.05 to 40, 0.1 to 50, 1 to 30, 5 to 20, or 10 to 20.

[0067] The content of the alcohol compound may be 80 to 98 mass% based on the total mass of the catalyst composition from the viewpoint of further enhancing the effect of suppressing color change of the quaternary ammonium salt, the effect of reducing coloration of the coating film, and the effect of improving low-temperature curing. From the same viewpoint, the content of the alcohol compound may be 80 mass% or more or 85 mass% or more, 98 mass% or less or 97 mass% or less, or 80 to 97 mass% or 85 to 98 mass% based on the total mass of the catalyst composition.

[0068] The catalyst composition may contain a blocking agent dissociating catalyst other than the quaternary ammonium salt. The content of the blocking agent dissociating catalyst other than the quaternary ammonium salt in the catalyst composition may be 0 to 0.5 mass %, or may be 0.2 mass % or less, or 0.1 mass % or less, based on the total mass of the blocking agent dissociating catalyst.

[0069] The catalyst composition can be prepared by mixing the quaternary ammonium salt, the carbonate diester compound, and any other optional ingredients.

[0070] <Blocked polyisocyanate composition> One embodiment of the present disclosure is a blocked polyisocyanate composition comprising a blocked polyisocyanate, a quaternary ammonium salt, and a carbonic acid diester compound. The blocked polyisocyanate composition may comprise the catalyst composition of the above embodiment. That is, the blocked polyisocyanate composition may be a composition comprising a blocked polyisocyanate and the catalyst composition of the above embodiment.

[0071] The above-mentioned blocked polyisocyanate composition contains a quaternary ammonium salt and a carbonic acid diester compound, and therefore can impart low-temperature curing properties to the coating composition. For the same reason, the above-mentioned blocked polyisocyanate composition can provide a coating composition that is less likely to undergo color change during the preparation of the coating film (before and after the coating film is cured).

[0072] (Blocked polyisocyanate) A blocked polyisocyanate is a compound derived from a polyisocyanate that does not have an isocyanate group blocked with a blocking agent (hereinafter also referred to as an "unblocked polyisocyanate"), and has at least a structure derived from the unblocked polyisocyanate and an isocyanate group blocked with a blocking agent (hereinafter also referred to as a "blocked isocyanate group").

[0073] [Unblocked polyisocyanate] The unblocked polyisocyanate is a compound having a plurality of isocyanate groups (free isocyanate groups). Examples of the unblocked polyisocyanate include aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates, and polyisocyanate derivatives thereof. Examples of the derivatives include isocyanurates, allophanates, biurets, and the like.

[0074] The unblocked polyisocyanate may not have an aromatic ring in order to improve the yellowing resistance of the cured coating film. That is, the unblocked polyisocyanate may be a non-aromatic polyisocyanate. Examples of the non-aromatic polyisocyanate include aliphatic polyisocyanates such as hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine triisocyanate, and trioxyethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated tetramethylxylene diisocyanate, and derivatives thereof. Examples of the derivative include isocyanurates, allophanates, and biuret. The derivative may be an isocyanate group-containing prepolymer obtained by reacting the polyisocyanate with a polyol, or may be a derivative of the prepolymer (e.g., isocyanurates, allophanates, and biuret). As the polyol, for example, a diol having 2 to 9 carbon atoms is used. 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.

[0075] The unblocked polyisocyanate may contain an aliphatic polyisocyanate having 4 to 6 carbon atoms or a derivative thereof from the viewpoint of further improving low-temperature curing properties, and may contain hexamethylene diisocyanate or a derivative thereof from the viewpoint of further improving low-temperature curing properties. In other words, the blocked polyisocyanate may have a structure derived from an aliphatic polyisocyanate having 4 to 6 carbon atoms or a derivative thereof, or may have a structure derived from hexamethylene diisocyanate or a derivative thereof. The derivative of an aliphatic polyisocyanate having 4 to 6 carbon atoms (for example, hexamethylene diisocyanate) may be at least one selected from the group consisting of an isocyanurate, an allophanate, and a biuret. These derivatives may be derivatives of the above-mentioned isocyanate group-containing prepolymer. Among these, when the derivative of hexamethylene diisocyanate is an isocyanurate, a higher coating hardness tends to be obtained. When the unblocked polyisocyanate contains an isocyanurate, from the viewpoint of further improving the hardness of the coating film, the content of the isocyanurate trimer based on the total mass of the unblocked polyisocyanate (isocyanurate trimer content) may be 50% by mass or more, and the content of the isocyanurate group relative to the total (100 mol%) of the isocyanurate group and allophanate group in the unblocked polyisocyanate (isocyanurate group content) may be more than 80 mol%. The upper limit of the isocyanurate trimer content may be 80% by mass, and the upper limit of the isocyanurate group content may be 99 mol%.

[0076] [Blocked isocyanate group] The blocked isocyanate group is an isocyanate group blocked with a blocking agent and has a structure derived from the blocking agent.

[0077] Examples of blocking agents include alcohol-based blocking agents such as methanol, ethanol, n-butanol, isobutanol, 2-ethylhexanol, butyl cellosolve, propylene glycol monomethyl ether, ethylene glycol, and benzyl alcohol; phenol-based blocking agents such as phenol, cresol, ethylphenol, butylphenol, and 2-hydroxypyridine; lactam-based blocking agents such as ε-caprolactam, δ-valerolactam, and γ-butyrolactam; oxime-based blocking agents such as formaldoxime, acetaldoxime, acetoneoxime, methylethylketoxime, methylisobutylketoxime, and cyclohexanoneoxime; imidazole, 2-methylimidazole, 4-methylimidazole, 2,4-dimethylimidazole, and the like. Examples of the blocking agent include imidazole-based blocking agents such as imidazole, 2-ethylimidazole, 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-heptadecylimidazole; pyrazole-based blocking agents such as 3,5-dimethylpyrazole, 3-methylpyrazole, and pyrazole; amine-based blocking agents such as diphenylamine, diisopropylamine, and isopropylethylamine; and triazole-based blocking agents such as triazole, 1,2,4-triazole, and 3,5-dimethyl-1,2,4-triazole. From the viewpoint of storage stability, an oxime-based blocking agent may be used. As the oxime-based blocking agent, methyl ethyl ketoxime is preferable. From the viewpoint of curability, a pyrazole-based blocking agent may be used. A preferred pyrazole blocking agent is 3,5-dimethylpyrazole.

[0078] In view of the above, in one embodiment, the blocked polyisocyanate may have 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.

[0079] The blocked polyisocyanate may have a free isocyanate group, but when the blocked polyisocyanate does not have a free isocyanate group, the storage stability can be further improved. From the viewpoint of further improving the storage stability, all of the effective isocyanate groups in the blocked polyisocyanate may be blocked isocyanate groups. Here, the effective isocyanate group means both the free isocyanate group and the blocked isocyanate group.

[0080] The blocked polyisocyanate can be obtained, for example, by reacting a polyisocyanate having a free isocyanate group, such as the unblocked polyisocyanate, with the blocking agent. That is, the blocked polyisocyanate can be a reaction product of a polyisocyanate having a free isocyanate group and the blocking agent. The polyisocyanate having a free isocyanate group and the blocking agent may each be used alone or in combination of two or more. However, when an aromatic polyisocyanate is not used as the polyisocyanate having a free isocyanate group, the yellowing resistance of the cured coating film can be further improved.

[0081] The blocked polyisocyanate may be a compound derived from a reaction product of a polyisocyanate having a free isocyanate group and a blocking agent. For example, the blocked polyisocyanate may be a compound obtained by reacting a reaction product of a polyisocyanate having a free isocyanate group and a blocking agent with a compound capable of reacting with the free isocyanate group in the reaction product (e.g., an active hydrogen group-containing compound, etc.).

[0082] The reaction between the polyisocyanate having a free isocyanate group and the blocking agent can be carried out according to the reaction conditions for a typical blocking reaction. The reaction may be carried out at room temperature or with heating. Regardless of whether or not heating is carried out, the temperature of the reaction solution may be, for example, 20 to 200°C.

[0083] The blocked polyisocyanates may be used alone or in combination of two or more. For example, two or more blocked polyisocyanates derived from different types of unblocked polyisocyanates may be used in combination.

[0084] The content of the block polyisocyanate may be 40% by mass or more, 60% by mass or more, or 80% by mass or more based on the total solid content of the block polyisocyanate composition from the viewpoint of easily obtaining a coating composition having excellent low-temperature curing properties. The content of the block polyisocyanate may be less than 100% by mass, 95% by mass or less, or 90% by mass or less based on the total solid content of the block polyisocyanate composition from the viewpoint of improving the storage stability of the coating. From these viewpoints, the content of the block polyisocyanate may be, for example, 40% by mass or more and less than 100% by mass, or 60 to 95% by mass or 80 to 90% by mass based on the total solid content of the block polyisocyanate composition. Note that, when the block polyisocyanate composition contains a solvent, the total solid content of the block polyisocyanate composition means the amount obtained by excluding the amount of the solvent from the total amount of the block polyisocyanate composition, and when the block polyisocyanate composition does not contain a solvent, it means the total amount of the block polyisocyanate composition.

[0085] (Quaternary ammonium salts and carbonate diester compounds) The details of the quaternary ammonium salt and the carbonate diester compound are the same as those of the quaternary ammonium salt and the carbonate diester compound contained in the catalyst composition. The ratio of the content of the carbonate diester compound to the content of the quaternary ammonium salt may be in the same range as the range exemplified as the ratio of the content of the carbonate diester compound to the content of the quaternary ammonium salt in the catalyst composition.

[0086] The content of the quaternary ammonium salt may be 0.0001 parts by mass or more, 0.001 parts by mass or more, 0.01 parts by mass or more, 0.1 parts by mass or more, or 1 part by mass or more, relative to 100 parts by mass of the blocked polyisocyanate, from the viewpoint of easily obtaining a coating composition having excellent low-temperature curing properties. The content of the quaternary ammonium salt may be 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less, relative to 100 parts by mass of the blocked polyisocyanate, from the viewpoint of improving the storage stability of the coating. From these viewpoints, the content of the quaternary ammonium salt may be, for example, 0.0001 to 40 parts by mass, 0.001 to 30 parts by mass, 0.01 to 20 parts by mass, 0.1 to 10 parts by mass, or 1 to 5 parts by mass, relative to 100 parts by mass of the blocked polyisocyanate. When the blocked polyisocyanate composition contains a catalyst composition, the content of the catalyst composition may be adjusted so that the content of the quaternary ammonium salt falls within the above range.

[0087] (Other Ingredients) The blocked polyisocyanate composition may further contain, as other components, components other than the blocked polyisocyanate, the quaternary ammonium salt, and the carbonate diester compound, such as additives such as pigments, dispersion stabilizers, viscosity modifiers, leveling agents, antigelling agents, light stabilizers, antioxidants, UV absorbers, heat resistance improvers, inorganic and organic fillers, plasticizers, lubricants, antistatic agents, reinforcing materials, and catalysts.

[0088] The blocked polyisocyanate composition may contain an alcohol compound as another component. The details of the alcohol compound are the same as those in the above embodiment.

[0089] The blocked polyisocyanate composition may contain a solvent as another component. Examples of the solvent include benzene, toluene, xylene, cyclohexane, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, n-butyl acetate, cellosolve acetate, 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. The content of the solvent may be 0 to 95% by mass, 5 to 90% by mass, or 10 to 80% by mass based on the total mass of the blocked polyisocyanate composition.

[0090] The blocked polyisocyanate composition may contain an unblocked polyisocyanate (e.g., polyisocyanate remaining as an unreacted product) or an unreacted blocking agent. The content of the unblocked polyisocyanate contained in the blocked polyisocyanate composition may be 5% by mass or less, or may be 0% by mass, based on the total solid content of the blocked polyisocyanate composition. The content of the unreacted blocking agent contained in the blocked polyisocyanate composition may be 5% by mass or less, or may be 0% by mass, based on the total solid content of the blocked polyisocyanate composition.

[0091] The effective isocyanate group content of the blocked polyisocyanate composition (hereinafter referred to as "effective NCO content") may be 4 to 28 mass%, 5 to 22 mass%, or 6 to 16 mass% from the viewpoint of further enhancing the curability of the coating material. Here, the effective NCO content is the isocyanate group present in the blocked polyisocyanate composition that can participate in a crosslinking reaction expressed in mass%, and can be rephrased as the content (free NCO content) of the free isocyanate group in the polyisocyanate composition obtained by dissociating the blocking agent from the blocked polyisocyanate relative to the total mass of the blocked polyisocyanate composition. The free NCO content can be determined by reacting the isocyanate group in the measurement sample (polyisocyanate composition obtained by dissociating the blocking agent from the blocked polyisocyanate) with an excess of secondary amine, and then back titrating the unreacted secondary amine with hydrochloric acid.

[0092] The above-described blocked polyisocyanate composition can be prepared by mixing the blocked polyisocyanate, the previously prepared catalyst composition, and other components that are optionally included. The blocked polyisocyanate composition can also be prepared by mixing the blocked polyisocyanate, a quaternary ammonium salt, a carbonic acid diester compound, and other components that are optionally included. The blocked polyisocyanate composition is used, for example, as a curing agent for a paint composition (e.g., a low-temperature curing paint composition). That is, another embodiment of the present disclosure is a curing agent for a paint (e.g., a low-temperature curing paint) that is composed of the blocked polyisocyanate composition.

[0093] <Paint composition> Another embodiment of the present disclosure is a coating composition containing a base agent and a curing agent, the coating composition containing a blocked polyisocyanate and the catalyst composition of the above embodiment. The coating composition may contain the above-mentioned blocked polyisocyanate composition. The details of the blocked polyisocyanate contained in the coating composition are the same as the details of the blocked polyisocyanate contained in the above-mentioned blocked polyisocyanate composition.

[0094] The coating composition may be a one-liquid type composition in which all of the components are contained in one liquid, or a multi-liquid type composition in which the components are present separately in multiple liquids. The multi-liquid type coating composition may comprise a first liquid containing a base agent and a second liquid containing a curing agent. The blocked polyisocyanate is contained in the second liquid as a curing agent, but the catalyst composition may be contained in either the first liquid or the second liquid. Similarly, when the coating composition contains other components that can be contained in the blocked polyisocyanate composition, these components may be contained in either the first liquid or the second liquid. When the catalyst composition is contained in the second liquid, the blocked polyisocyanate composition of the above embodiment may be the second liquid.

[0095] The coating composition contains a blocked polyisocyanate and the catalyst composition of the embodiment, and therefore has excellent low-temperature curing properties. For the same reason, the coating composition is less likely to cause color changes during the preparation of the coating film (before and after the coating film is cured), and a coating film with little coloring can be easily formed.

[0096] The base agent contains, for example, an active hydrogen group-containing compound. Examples of the active hydrogen group include a hydroxy group and an amino group. The active hydrogen group-containing compound has an average number of functional groups (average number of active hydrogen groups) of 2 or more, for example, 2 to 50. Examples of active hydrogen-containing compounds having such an average number of functional groups include polyols, polyamines, and amino alcohols. In particular, when the base agent contains a polyol as the active hydrogen group-containing compound, it is easy to obtain better low-temperature curing properties and a coating film with less coloring.

[0097] The number average molecular weight of the active hydrogen group-containing compound is, for example, 500 to 20,000, and may be 500 to 10,000. Examples of active hydrogen group-containing compounds having 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 are resins having active hydrogen groups). From the viewpoints of coating film performance such as gloss, body feel, hardness, durability, flexibility, and drying properties, and 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 may be used.

[0098] The blending ratio of the base agent and the curing agent in the coating composition may 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. 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 may be 1 / 9 to 9 / 1, or 2 / 8 to 8 / 2, in terms of molar ratio. When the molar ratio is within the above range, better curability can be obtained.

[0099] The content of the catalyst composition in the coating composition may be adjusted so that the content of the quaternary ammonium salt per 100 parts by mass of the blocked polyisocyanate falls within the above-mentioned range (e.g., 0.0001 to 40 parts by mass), similar to the content of the catalyst composition in the blocked polyisocyanate composition.

[0100] The coating composition can be used as an automotive topcoat paint, anti-chipping paint, electrodeposition paint, paint for automotive parts, paint for automotive repair, pre-coated metal and rust-proof steel plate for metal products such as home appliances and office equipment, paint for building materials, paint for plastics, adhesive, adhesion promoter, sealant, etc.

[0101] <Coating film and coating film formation method> Another embodiment of the present disclosure is a coating film formed from the coating composition of the above embodiment. Also, another embodiment of the present disclosure is a method for forming a coating film, comprising the steps of applying the coating composition of the above embodiment to a substrate and curing the coating film (uncured coating film) made of the coating composition.

[0102] The coating film may be an uncured coating film made of a mixture of the base agent and the curing agent in the coating composition of the above embodiment, or may be a coating film (cured coating film) formed by curing the uncured coating film. The thickness of the coating film is, for example, 5 to 40 μm. The coating film may be a thin film with a thickness of less than 20 μm.

[0103] The coating composition may be applied by a known method such as roll coating, curtain flow coating, spray coating, electrostatic coating, bell coating, electrodeposition coating, etc. The amount of coating composition to be applied, the thickness of the coating film, etc. may be appropriately determined depending on the material of the surface to be coated, etc.

[0104] The coating film (uncured coating film) made of the coating composition may be cured by heating the coating film. The heating temperature (baking temperature) may be, for example, 200° C. or lower, and the heating time (baking time) may be, for example, 10 to 180 minutes. According to the coating composition of this embodiment, even when baking is performed at a low temperature of 100° C. or lower (for example, 60 to 100° C.), a cured coating film having good hardness can be formed.

[0105] Examples of the substrate include molded articles made of materials such as stainless steel, phosphate-treated steel, zinc-coated steel, iron, copper, aluminum, brass, glass, acrylic polyol, polycarbonate resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene phthalate resin, polystyrene resin, AS resin, ABS resin, polycarbonate-ABS resin, 6-nylon resin, 6,6-nylon resin, MXD6 nylon resin, polyvinyl chloride resin, polyvinyl alcohol resin, polyurethane resin, phenol resin, melamine resin, polyacetal resin, chlorinated polyolefin resin, polyolefin resin, polyamide resin, polyether ether ketone resin, polyphenylene sulfide resin, NBR resin, chloroprene resin, SBR resin, and SEBS resin, and surface-treated articles of the molded articles. The surface-treated article may be a molded article (surface-treated molded article) made of an olefin resin such as polyethylene or polypropylene that has been subjected to a surface treatment such as a corona discharge treatment. EXAMPLES

[0106] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0107] <Synthesis Example 1> (Synthesis of quaternary ammonium salts) A 200 ml autoclave was charged with 15.4 g of dimethylmono n-octylamine (Tokyo Chemical Industry Co., Ltd.), 13.2 g of dimethyl carbonate (Tokyo Chemical Industry Co., Ltd.), and 31.4 g of methanol (Kishida Chemical Co., Ltd.), and the mixture was stirred at 110° C. for 12 hours to react. The reaction liquid was collected in a container (one-necked eggplant flask), and the pressure in the container was reduced to 30° C. to remove unreacted dimethyl carbonate and methanol, yielding 24.2 g of trimethylmono n-octylammonium monomethyl carbonate (hereinafter referred to as “TMOA-MC”).

[0108] <Synthesis Example 2> (Synthesis of Polyisocyanate) In a four-neck flask equipped with a stirrer, a thermometer, a heating device, a nitrogen seal tube, and a cooling tube, 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 charged, and a urethane reaction was carried out for 2 hours at 80°C under a nitrogen stream. Then, 0.04 g of potassium 2-ethylhexanoate (manufactured by Tokyo Chemical Industry Co., Ltd.), which is an isocyanurate catalyst, was added, and an isocyanurate reaction was carried out for 2 hours at 70°C. After the NCO content reached 40.0 mass%, 0.15 g of JP-508 (manufactured by Johoku Chemical Industry Co., Ltd.) was added, a termination reaction was carried out, and the reaction liquid was cooled to room temperature. This reaction liquid was subjected to thin-film distillation at a temperature of 130°C and a pressure of 0.04 kPa to remove unreacted HDI, thereby obtaining a purified polyisocyanate (hereinafter referred to as "Polyisocyanate A-1"). The NCO content of Polyisocyanate A-1 was 21.8% by mass, and the viscosity at 25°C was approximately 2,500 mPa s.

[0109] ( 1 H-NMR: Measurement of isocyanurate group content) Polyisocyanate A-1 1 H-NMR measurement was carried out to determine the isocyanurate group content (the content of isocyanurate groups relative to the total of isocyanurate groups and allophanate groups (100 mol%)). Specifically, the isocyanurate group content was calculated from the area of ​​the signal of the hydrogen atom of the methylene group adjacent to the nitrogen atom of the isocyanurate group at around 3.7 ppm and the signal of the hydrogen atom bonded to the nitrogen atom of the allophanate group at around 8.5 ppm. The isocyanurate group content was 89 mol%. 1 H-NMR measurements were performed under the following conditions. [Measurement conditions] (1) Measuring device: ECX400M (manufactured by JEOL Ltd., 1 H-NMR) (2) Measurement temperature: 23℃ (3) Sample concentration: 0.1 g / 1 ml (4) Number of times accumulated: 16 (5) Relaxation time: 5 seconds (6) Solvent: Deuterium dimethyl sulfoxide (7) Chemical shift standard: hydrogen atom signal of methyl group in deuterium dimethyl sulfoxide (2.5 ppm)

[0110] <Examples 1 to 8 and Comparative Example 1> (Preparation of Catalyst Composition) The catalyst compositions (catalyst compositions 1 to 8) of Examples 1 to 8 were prepared by mixing 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, in the mass ratio [a / b] (quaternary ammonium salt / carbonate diester compound) shown in the following Table 1. In Comparative Example 1, no carbonate diester compound was used, and TMOA-MC was used as it is as a catalyst.

[0111] (Evaluation of color fastness) Catalyst compositions 1 to 8 were stored at 80°C for 48 hours, and the b* values ​​of the catalyst compositions according to the CIE Lab standard were measured before and after storage using a spectrophotometer COH7700 manufactured by Nippon Denshoku Kogyo Co., Ltd. The "rate of change in b* value" was calculated from the b* values ​​before and after storage (initial b* value and b* value after storage) using the following formula, and the resistance of the catalyst compositions to discoloration over time (discoloration resistance) was evaluated based on the rate of change. In the same manner, the discoloration resistance of the catalyst of Comparative Example 1 (TMOA-MC) was also evaluated. Rate of change in b* value (unit: %) = 100 x (b* value after storage - initial b* value) / initial b* value

[0112] The evaluation criteria are shown below, and the results are shown in Table 1. If the evaluation was B, the catalyst composition was evaluated to have sufficient discoloration resistance. A: The rate of change in b* value is between 0% and 30% B: The change in b* value is between 30% and 60% C: Change in b* value is 60% or more

[0113] (Preparation of Blocked Polyisocyanate Composition) Blocked polyisocyanate compositions of Examples 1 to 8 and Comparative Example 1 (blocked polyisocyanate compositions 1 to 9) were prepared using the catalyst compositions 1 to 8 and the catalyst of Comparative Example 1, respectively, by the following method.

[0114] 515 g of polyisocyanate A-1 and 250 g of butyl acetate were charged into a four-neck flask equipped with a stirrer, thermometer, heating device, nitrogen seal tube, and cooling tube, and stirred for 30 minutes. Then, 234 g of methyl ethyl ketoxime (manufactured by Ube Industries, "MEKO" in the table) (equivalent ratio to the amount of polyisocyanate A-1 mixed is 1.0) was charged in three separate portions so that the temperature did not exceed 80°C. After that, the reaction was carried out at 70°C for 2 hours, and the infrared absorption spectrum (IR measurement) showed that the NCO group peak (2270 cm -1 When the vapor (around 100% water) disappeared, the mixture was cooled to room temperature, and catalyst compositions 1 to 8 or the catalyst of Comparative Example 1 were added so that the amount of quaternary ammonium salt added was 22.5 g, followed by stirring for 30 minutes. By the above operations, blocked polyisocyanate compositions 1 to 9 were obtained, respectively.

[0115] (Preparation of Coating Composition) Using the blocked polyisocyanate compositions 1 to 9, coating compositions (coating compositions 1 to 9) of Examples 1 to 8 and Comparative Example 1 were prepared. Specifically, the coating compositions were prepared by mixing Acrydic A-801 (manufactured by DIC Corporation, acrylic polyol, solid content concentration 50 mass%, hydroxyl value 50 mgKOH / g, product name, "A801" in the table) as the main agent, the blocked polyisocyanate composition ("BPI" in the table) as the curing agent, and butyl acetate (manufactured by Kishida Chemical Co., Ltd., "BtAc" in the table). The blending amount of each component was as shown in Table 1.

[0116] (Paint film preparation and coloring evaluation) Coating compositions 1 to 9 were applied to substrates under the following conditions and cured to obtain coating films (cured coating films) of Examples 1 to 8 and Comparative Example 1, respectively. At this time, a BYK-GARDNER colorimeter (product name: SPECTRO2GUIDE) was used to measure the b* value of the cured coating film according to the CIE Lab standard. The results are shown in Table 1. The substrate used was a color steel plate (white) (manufactured by Yutaka Panel Service, 0.8 mm thick). [conditions] - Application method: Use applicator ·Humidity condition: 50%RH ·Temperature conditions: 23℃ Drying (curing) conditions: Forced drying at 160℃ for 1 hour Film thickness: approx. 20μm

[0117] (Evaluation of low-temperature curing: Measurement of coating hardness) Coating compositions 1 to 9 were applied to substrates under the following conditions and cured to obtain coating films (cured coating films) of Examples 1 to 8 and Comparative Example 1. A color steel plate (white) (manufactured by Yutaka Panel Service Co., Ltd., 0.8 mm thick) was used as the substrate. [conditions] - Application method: Use applicator ·Humidity condition: 50%RH ·Temperature conditions: 23℃ Drying (curing) conditions: Forced drying at 80℃ for 20 minutes Film thickness: approx. 20μm

[0118] The hardness of the coating film obtained above (cured coating film) was measured under the following conditions in accordance with ISO 14577. The results are shown in Table 1. [conditions] Test equipment: Fischerscope HM2000 (manufactured by Fisher Instruments) Indenter: Vickers diamond Test load: 5mN Test temperature: 25℃

[0119] <Example 9> (Preparation of Blocked Polyisocyanate Composition) 500 g of polyisocyanate A-1 and 250 g of butyl acetate were charged into a four-neck flask equipped with a stirrer, a thermometer, a heating device, a nitrogen seal tube, and a cooling tube, and the mixture was stirred for 30 minutes. Then, 249 g of 3,5-dimethylpyrazole (manufactured by Tokyo Chemical Industry Co., Ltd., "DMP" in the table) (equivalent ratio to the amount of polyisocyanate A-1 mixed is 1.0) was charged in three separate portions so that the temperature did not exceed 80°C. The mixture was then reacted at 70°C for 2 hours, and the infrared absorption spectrum (IR measurement) showed a peak of the NCO group (2270 cm -1When the mixture had disappeared (around 1000 g), it was cooled to room temperature, and 22.5 g of the catalyst composition of Example 4 (catalyst composition 4) was added so that the amount of the quaternary ammonium salt added was 22.5 g, and the mixture was stirred for 30 minutes. By the above operations, a blocked polyisocyanate composition 10 was obtained.

[0120] (Preparation of coating composition, production and evaluation of coating film) Coating composition 10 was prepared in the same manner as in Example 1, except that blocked polyisocyanate composition 10 was used instead of blocked polyisocyanate composition 1, and the amounts of each component were as shown in Table 1. In addition, a coating film (cured coating film) was prepared in the same manner as in Example 1, except that coating composition 10 was used instead of coating composition 1, and the coating film coloring evaluation (measurement of b*) and coating film hardness were measured. The results are shown in Table 1.

[0121] <Example 10> Catalyst composition 11 was prepared in the same manner as in Example 2, except that a 10 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 mixed mass ratio of each component "quaternary ammonium salt (TMA-OH) / carbonic acid diester compound (DMC) / alcohol compound (methanol)" (mass ratio [a / b / c] in the table) was set to 1 / 0.5 / 9, and the discoloration resistance of catalyst composition 11 was evaluated. The results are shown in Table 2.

[0122] Blocked polyisocyanate composition 11 was prepared in the same manner as in Example 1, except that catalyst composition 11 was used instead of catalyst composition 1, and coating composition 11 was prepared in the same manner as in Example 1, except that blocked polyisocyanate composition 11 was used instead of blocked polyisocyanate composition 1, and the blending amounts of each component were as shown in Table 2. In addition, a coating film was prepared in the same manner as in Example 1, except that coating composition 11 was used instead of coating composition 1, and the coloring evaluation and hardness measurement of the coating film were performed. The results are shown in Table 2.

[0123] <Examples 11 to 12> Instead of dimethyl carbonate, diethyl carbonate (Tokyo Chemical Industry Co., Ltd., "DEC" in the table) or ethylene Catalyst compositions 12 to 13 were prepared in the same manner as in Example 10, except that carbonate (manufactured by Tokyo Chemical Industry Co., Ltd., "EC" in the table) was used, and the discoloration resistance of catalyst compositions 12 to 13 was evaluated. The results are shown in Table 2.

[0124] Block polyisocyanate compositions 12 to 13 were prepared in the same manner as in Example 1, except that catalyst compositions 12 to 13 were used instead of catalyst composition 1, and coating compositions 12 to 13 were prepared in the same manner as in Example 1, except that block polyisocyanate compositions 12 to 13 were used instead of block polyisocyanate composition 1, and the blending amounts of each component were as shown in Table 2. In addition, coating films were produced in the same manner as in Example 1, except that coating compositions 12 to 13 were used instead of coating composition 1, and the coloring evaluation and hardness measurement of the coating films were performed. The results are shown in Table 2.

[0125] <Example 13> Catalyst composition 14 was prepared in the same manner as in Example 1, except that methanol (manufactured by Tokyo Chemical Industry Co., Ltd.) was mixed in addition to TMOA-MC and DMC, and the mixing mass ratio of each component "quaternary ammonium salt (TMA-OH) / carbonic acid diester compound (DMC) / alcohol compound (methanol)" (mass ratio [a / b / c] in the table) was set to 1 / 0.5 / 9, and the discoloration resistance of catalyst composition 14 was evaluated. The results are shown in Table 2.

[0126] Blocked polyisocyanate composition 14 was prepared in the same manner as in Example 1, except that catalyst composition 14 was used instead of catalyst composition 1, and coating composition 14 was prepared in the same manner as in Example 1, except that blocked polyisocyanate composition 14 was used instead of blocked polyisocyanate composition 1, and the blending amounts of each component were as shown in Table 2. In addition, a coating film was produced in the same manner as in Example 1, except that coating composition 14 was used instead of coating composition 1, and the coloring evaluation and hardness measurement of the coating film were performed. The results are shown in Table 2.

[0127] <Example 14> Catalyst composition 15 was prepared in the same manner as in Example 13, except that the mixture mass ratio of the components in the catalyst composition, "quaternary ammonium salt (TMA-OH) / carbonic acid diester compound (DMC) / alcohol compound (methanol)" (mass ratio [a / b / c] in the table) was set to 1 / 0.5 / 18, and the discoloration resistance of catalyst composition 15 was evaluated. The results are shown in Table 2.

[0128] Blocked polyisocyanate composition 15 was prepared in the same manner as in Example 1, except that catalyst composition 15 was used instead of catalyst composition 1, and coating composition 15 was prepared in the same manner as in Example 1, except that blocked polyisocyanate composition 15 was used instead of blocked polyisocyanate composition 1, and the blending amounts of each component were as shown in Table 2. In addition, a coating film was produced in the same manner as in Example 1, except that coating composition 15 was used instead of coating composition 1, and the coloring evaluation and hardness measurement of the coating film were performed. The results are shown in Table 2.

[0129] <Comparative Example 2> Blocked polyisocyanate composition 16 was prepared in the same manner as in Comparative Example 1, except that TMA-OH was used as it was as a catalyst, and coating composition 16 was prepared in the same manner as in Example 1, except that blocked polyisocyanate composition 16 was used instead of blocked polyisocyanate composition 1, and the amounts of each component were as shown in Table 2. In addition, a coating film was produced in the same manner as in Example 1, except that coating composition 16 was used instead of coating composition 1, and the coating film hardness was measured. The results are shown in Table 2.

[0130] [Table 1]

[0131] [Table 2]

Claims

1. A catalyst composition for use in dissociating a blocking agent from a blocked polyisocyanate, comprising: A catalyst composition comprising a quaternary ammonium salt and a carbonate diester compound.

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

3. 2. The catalyst composition of claim 1, wherein the quaternary ammonium salt comprises a quaternary ammonium cation represented by formula (1): 【Chemistry 1】 [In formula (1), R １ represents an alkyl group having 1 to 16 carbon atoms which may have a hydroxy 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 carbon atoms.

4. The catalyst composition according to claim 1 , wherein the carbonate diester compound comprises a compound represented by the following formula (2): 【Chemistry 2】 [In formula (2), R ５ and R ６ each independently represents an aliphatic saturated hydrocarbon group having 1 to 16 carbon atoms; R ５ and R ６ may be linked to each other to form a ring.

5. The catalyst composition of claim 1 further comprising 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 according to claim 6, wherein the content of the quaternary ammonium salt is 0.0001 to 40 parts by mass per 100 parts by mass of the blocked polyisocyanate.

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

9. 7. The blocked polyisocyanate composition according to 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 comprising a base agent and a curing agent, the curing agent comprises a blocked polyisocyanate; A coating composition, wherein the base agent or the curing agent comprises the catalyst composition according to any one of claims 1 to 5.

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

12. A method for forming a coating film, comprising the steps of applying the coating composition according to claim 10 to a substrate and heating the substrate at 60 to 100°C to cure the coating film made of the coating composition.