JP6765276B2 - Block isocyanate composition, one-component paint composition and coating film - Google Patents

Description

The present invention relates to blocked isocyanate compositions, one-component coating compositions and coatings.

The polyisocyanate composition, together with a melamine-based curing agent, is widely used as a heat-crosslinking type curing agent for baking paints. In recent years, it has been pointed out that formalin is generated when a melamine-based curing agent is used, and from the viewpoints of the global environment, safety, hygiene, etc., a polyisocyanate (blocked polyisocyanate) composition blocked by a blocking agent is drawing attention. Has been done.
Conventionally, oximes, phenols, alcohols, and lactams are known as blocking agents for the blocked polyisocyanate composition.
Examples of the blocked polyisocyanate composition capable of forming a crosslinked coating film at a relatively low temperature include a pyrazole-based block polyisocyanate composition (see, for example, Patent Document 1) and an aliphatic secondary amine-based block polyisocyanate composition (see Patent Document 1). For example, Patent Document 2) is disclosed.
Examples of the blocked polyisocyanate composition capable of further lowering the baking temperature include a blocked polyisocyanate composition containing a malonic acid diester compound as a blocking agent (see, for example, Patent Document 3), diethyl malonate and ethyl acetoacetate. Blocked polyisocyanate compositions using and as a blocking agent (see, for example, Patent Documents 4 and 5) and the like have been proposed.

European Patent Application Publication No. 159117 JP-A-59-4658 JP-A-57-121065 Japanese Patent Application Laid-Open No. 8-225630 JP-A-9-255915

However, the blocked polyisocyanate composition formed by using the conventional blocking agent generally requires a high baking temperature of 140 ° C. or higher, so that the energy cost becomes very high. Further, there is a problem that a block polyisocyanate composition that requires high-temperature baking cannot be used for processing into a plastic having low heat resistance.
In the blocked polyisocyanate composition as described in Patent Documents 1 and 2, a baking temperature of about 120 ° C. is required, and further reduction of the baking temperature is desired.
Further, in applications such as painting of new automobiles, a coating film such as a clear layer may be further laminated on a coating film layer using a conventional block polyisocyanate composition. As the block polyisocyanate composition used in such a case, a block polyisocyanate composition capable of forming a crosslinked coating film at a temperature of 100 ° C. or lower and having good adhesion when laminated is desired.
On the other hand, the blocked polyisocyanate compositions as described in Patent Documents 3, 4 and 5 can form a crosslinked coating film at a temperature of 100 ° C. or lower, but these blocked polyisocyanate compositions were used. There is a further problem in adhesion when a coating film is further laminated on the coating film layer.

Therefore, an object of the present invention is to provide a blocked isocyanate composition having excellent low-temperature curability and excellent adhesion to an upper coating film when the coating film is laminated.

As a result of diligent research, the present inventors have discovered that a blocked isocyanate composition having a specific structure can achieve the above-mentioned problems, and have completed the present invention.
That is, the present invention is as follows.

[1] A blocked isocyanate compound obtained from a triisocyanate compound represented by the following general formula (I) and a blocking agent is contained, and the blocking agent comprises a malonic acid diester compound represented by the following general formula (II). see contains at least one selected from the group, isocyanate group contained in the triisocyanate compound, 80 equivalent% or more is blocked by the malonic acid diester compound, blocked isocyanate composition.

［一般式（Ｉ）中、複数あるＹ^１は、それぞれ独立に、単結合、あるいは、エステル構造及び／又はエーテル構造を含んでもよい炭素数１〜２０の２価の炭化水素基である。複数あるＹ^１は、それぞれ同一であってもよく異なっていてもよい。Ｒ^１は、水素原子又は炭素数１〜１２の１価の炭化水素基である。］

[In the general formula (I), plural Y ¹ are each independently a single bond or a divalent hydrocarbon group having ester structure and / or which may having 1 to 20 carbon atoms contain an ether structure. Plurality of Y ¹ may be different from each other may be the same. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. ]

［一般式（ＩＩ）中、Ｒ^２及びＲ^３は、それぞれ独立に、炭素数１〜８個のアルキル基、シクロアルキル基、フェニル基、またはベンジル基を示す。Ｒ^２及びＲ^３は、同一であってもよく、異なっていてもよい。］

[In the general formula (II), R ² and R ³ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, or a benzyl group. R ² and R ³ may be the same or different. ]

[2] The blocked isocyanate composition according to [1], wherein the blocking agent further comprises at least one selected from the group consisting of β-ketoester compounds represented by the following general formula (III).

［一般式（ＩＩＩ）中、Ｒ^４及びＲ^５は、それぞれ独立に、炭素数１〜８個のアルキル基、シクロアルキル基、フェニル基、またはベンジル基を示す。Ｒ^４及びＲ^５は、同一であってもよく、異なっていてもよい。］

[In the general formula (III), R ⁴ and R ⁵ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, or a benzyl group. R ⁴ and R ⁵ may be the same or different. ]

[3] The blocked isocyanate composition according to [2], wherein the molar ratio of the malonic acid diester compound to the β-ketoester compound exceeds 1.0.
[4] A one-component coating composition containing the blocked isocyanate composition according to any one of [1] to [3] and a polyol.
[5] A coating film obtained by curing the one-component coating composition according to [4].

According to the present invention, it is possible to provide a blocked isocyanate composition having excellent low-temperature curability and excellent adhesion to an upper coating film when the coating film is laminated.

Hereinafter, embodiments for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

As used herein, the term "polyisocyanate" refers to a polymer in which a plurality of monomers having one or more isocyanate groups (-NCO) are bonded.
As used herein, the term "polypoly" refers to a compound having two or more hydroxy groups (-OH).
In the present specification, unless otherwise specified, "(meth) acrylic" includes methacrylic and acrylic, and "(meth) acrylate" includes methacrylate and acrylate.

<Blocked isocyanate composition>
The blocked isocyanate composition of the present invention contains a blocked isocyanate compound obtained from a triisocyanate compound represented by the general formula (I), a blocking agent, and the like.

≪Blocked isocyanate compound≫
In the present embodiment, the blocked isocyanate compound is obtained from the triisocyanate compound represented by the following general formula (I) and the blocking agent.

［一般式（Ｉ）中、複数あるＹ^１は、それぞれ独立に、単結合、あるいは、エステル構造及び／又はエーテル構造を含んでもよい炭素数１〜２０の２価の炭化水素基である。複数あるＹ^１は、それぞれ同一であってもよく異なっていてもよい。Ｒ^１は、水素原子又は炭素数１〜１２の１価の炭化水素基である。］

[In the general formula (I), plural Y ¹ are each independently a single bond or a divalent hydrocarbon group having ester structure and / or which may having 1 to 20 carbon atoms contain an ether structure. Plurality of Y ¹ may be different from each other may be the same. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. ]

[Triisocyanate compound represented by the general formula (I)]
・ General formula (I)
[Y ¹ ]
In the general formula (I), Y ¹ there are a plurality, each independently represent a single bond or a divalent hydrocarbon group having ester structure and / or which may having 1 to 20 carbon atoms contain an ether structure. Y ¹ existing in plural numbers may be different from each other may be the same.
The divalent hydrocarbon group having 1 to 20 carbon atoms which may contain an ester structure and / or an ether structure includes a group represented by − (CH ₂ ) _n1 −X− (CH ₂ ) _n2 − (n1 and n2). Are independently integers of 0 to 10. However, neither n1 nor n2 becomes 0, and it is preferable that the side of n1 and n2 that is bound to NCO is 1 or more. X is an ester group or an ether group).
When it is desired to increase the reaction rate, it is preferable that X is an ester group.
n1 and n2 are preferably 0 to 4, more preferably 0 to 2. As the combination of n1 and n2, for example, a combination of n1 = 0 and n2 = 2 and a combination of n1 = 2 and n2 = 2 are preferable.

[R ¹ ]
R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. The hydrocarbon group in R ¹ is not particularly limited, and examples thereof include an alkyl group, an alkenyl group, and an alkynyl group. A hydrogen atom is preferable as R ¹ .

Since the triisocyanate [A] used in the present invention has a low viscosity, it is preferable that a plurality of hydrocarbon groups in Y ¹ have an aliphatic group and / or an aromatic group.
Further, R ¹ is preferably hydrogen. Further, R ³¹ is preferably hydrogen.
Further, in order to improve the weather resistance when used as a curing agent for a coating composition, it is preferable that a plurality of hydrocarbon groups in Y ¹ have an aliphatic group and / or an alicyclic group.

Separately, at least one of Y ¹ there are multiple for holding the heat resistance, it is preferred to have an ester group. Examples of examples corresponding to these classifications are 4-isocyanate methyl-1,8-octamethylene diisocyanate (hereinafter referred to as NTI, molecular weight 251) disclosed in Japanese Patent Publication No. 63-15264, JP-A-57-. 1,3,6-hexamethylene triisocyanate (hereinafter referred to as HTI, molecular weight 209) disclosed in Japanese Patent Publication No. 198760, bis (2-isocyanatoethyl) 2 disclosed in Japanese Patent Publication No. 4-1033. -Isocyanatoglutarate (hereinafter referred to as GTI, molecular weight 311), lysine triisocyanate disclosed in JP-A-53-135931 (hereinafter referred to as LTI, molecular weight 267) and the like can be mentioned.
Among these, NTI, GTI or LTI is preferable, NTI or LTI is more preferable, and LTI is particularly preferable, from the viewpoint of further improving the reactivity of the isocyanate group.

Further, in order to keep the hydrolysis resistance, at least one preferably contain only hydrocarbon group, all of the hydrocarbon groups of Y ¹ there are a plurality of Y ¹ there are a plurality of It is more preferable that it is composed of only.
Examples of examples corresponding to this classification include 4-isocyanate methyl-1,8-octamethylene diisocyanate (hereinafter referred to as NTI, molecular weight 251) disclosed in Japanese Patent No. 1468856, JP-A-57-198760. , 1,3,6-hexamethylene triisocyanate (hereinafter referred to as HTI, molecular weight 209) and the like disclosed in the above.

It preferably contains an ester structure in order to enhance the reactivity of the isocyanate group when used as a curing agent in the coating composition.
Examples of cases corresponding to this classification include bis (2-isocyanatoethyl) 2-isocyanatoglutarate (hereinafter referred to as GTI, molecular weight 311) disclosed in JP-A-4-1033, and Japanese Patent Application Laid-Open No. Examples thereof include lysine triisocyanate (hereinafter referred to as LTI, molecular weight 267) disclosed in Japanese Patent Application Laid-Open No. 53-135931.

The triisocyanate used in this embodiment can be obtained by, for example, isocyanate-forming an amino acid derivative or an amine such as an ether amine or an alkyl triamine. As the amino acid derivative, for example, 2,5-diaminovaleric acid, 2,6-diaminohexanoic acid, aspartic acid, glutamic acid and the like can be used. Since these amino acids are diamine monocarboxylic acids or monoamine dicarboxylic acids, the carboxyl groups are esterified with alkanolamines such as ethanolamine. The triamine having an ester group thus obtained can be made into a triisocyanate containing an ester structure by phosgenation or the like.

Examples of the ether amine include the trade name "D403" of Mitsui Chemicals Fine Co., Ltd., which is a polyoxyalkylene triamine. These are triamines and can be made into triisocyanates containing an ether structure by phosgenation of amines or the like.
Examples of the alkyl triamine include triisocyanatononane (4-aminomethyl-1,8-octanediamine and the like. These are triamines, and the triisocyanate contains only a hydrocarbon by phosgenization of the amine or the like. Can be done.

The molecular weight of the triisocyanate used in this embodiment is preferably 139 to 1000. The lower limit of the molecular weight is preferably 150, more preferably 180, and particularly preferably 200. The upper limit of the molecular weight is preferably 800, more preferably 600, and particularly preferably 400. When the molecular weight is at least the above lower limit value, crystallinity can be suppressed, and when it is at least the above upper limit value, low viscosity can be achieved.

[Blocking agent]
In the blocked isocyanate composition of the present embodiment, as the blocking agent, at least one selected from the group consisting of malonic acid diester compounds represented by the following formula (II) (hereinafter, also simply referred to as "malonic acid diester compounds"). including.

［一般式（ＩＩ）中、Ｒ^２及びＲ^３は、それぞれ独立に、炭素数１〜８個のアルキル基、シクロアルキル基、フェニル基、またはベンジル基を示す。Ｒ^２及びＲ^３は、同一であってもよく、異なっていてもよい。］

[In the general formula (II), R ² and R ³ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, or a benzyl group. R ² and R ³ may be the same or different. ]

In the above general formula (II), R ² and R ³ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, and a benzyl group. R ² and R ³ may be the same or different, but are preferably the same because of their availability.
When R ² and R ³ represent an alkyl group or a cycloalkyl group having 8 or less carbon atoms, the effective NCO content can be increased and the compatibility with the main agent or the like when used as a coating material is improved. Tends to be able to.
Among these, those showing an alkyl group having 1 to 8 carbon atoms are preferable, and an alkyl group having 1 to 4 carbon atoms is preferable. More specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or an n-butyl group is preferable, a methyl group or an ethyl group is more preferable, and an ethyl group is particularly preferable. Here, the effective NCO content is an isocyanate content (mass%) that is potentially present with respect to the total amount (100% by mass) of the blocked isocyanate composition.

In the blocked isocyanate composition of the present embodiment, a part of the isocyanate groups (located at the terminal) contained in the triisocyanate is blocked (protected) with a blocking agent.

As the blocking agent of the present embodiment, at least one selected from the group consisting of malonic acid diester compounds is used. When the isocyanate group is blocked by these malonic acid diester compounds, the blocked isocyanate group has an amide structure as shown in the following general formula (II-1) or an isomer thereof.

［一般式（ＩＩ−１）中、Ｒ^０はトリイソシアネート残基、Ｒ^２及びＲ^３は各々独立に、炭素数１〜８のアルキル基、シクロアルキル基、フェニル基、ベンジル基を示す。Ｒ^２及びＲ^３は同一であってもよく、異なっていてもよい］

[In the general formula (II-1), R ⁰ represents a triisocyanate residue, and R ² and R ³ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, and a benzyl group. R ² and R ³ may be the same or different]

Specific examples of the malonic acid diester compound are not particularly limited, but for example, dimethyl malonate, diethyl malonate, din-propyl malonic acid, diisopropyl malonic acid, din-butyl malonic acid, diisobutyl malonate, dimalonic acid di. Examples thereof include t-butyl, methyl malonic acid t-butyl ester, din-hexyl malonic acid, di2-ethylhexyl malonic acid, diphenyl malonate, and dibenzyl malonate. Among them, dimethyl malonate, diethyl malonate, din-propyl malonate, diisopropyl malonate, din-butyl malonate, diisobutyl malonate, dit-butyl malonate, methyl t-butyl ester malonic acid, malonic acid Din-hexyl and di2-ethylhexyl malonate are preferred. More preferably, it is dimethyl malonate, diethyl malonate, di-propyl malonate, diisopropyl malonate, and di-butyl malonate, more preferably dimethyl malonate, and diethyl malonate, and even more preferably. Diethyl malonate. The malonic acid diester compounds shown above may be used alone or in combination of two or more.

From the viewpoint of low temperature curability, the isocyanate group contained in the triisocyanate is preferably blocked by 50 equivalent% or more with the malonic acid diester compound, more preferably 60 equivalent% or more, and particularly preferably 80 equivalent% or more.

In the blocked isocyanate composition of the present embodiment, the blocking agent is composed of a group consisting of a malonic acid diester compound and a β-ketoester compound represented by the following formula (III) (hereinafter, also simply referred to as “β-ketoester compound”). It is preferable to include at least one selected from the viewpoint of crystallinity at low temperature.

［一般式（ＩＩＩ）中、Ｒ^４及びＲ^５は、それぞれ独立に、炭素数１〜８個のアルキル基、シクロアルキル基、フェニル基、またはベンジル基を示す。Ｒ^４及びＲ^５は、同一であってもよく、異なっていてもよい。］

[In the general formula (III), R ⁴ and R ⁵ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, or a benzyl group. R ⁴ and R ⁵ may be the same or different. ]

In the general formula (III), the description of the alkyl group having 1 to 8 carbon atoms, the cycloalkyl group, the phenyl group, or the benzyl group of R ⁴ and R ⁵ is the same as that of R ² and R ³ .

In the above formula (III), R ² and R ³ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, and a benzyl group. R ² and R ³ may be the same or different, but are preferably the same because of their availability.
When R ² and R ³ represent an alkyl group or a cycloalkyl group having 8 or less carbon atoms, the effective NCO content can be increased and the compatibility with the main agent or the like when used as a coating material is improved. Tends to be able to.
Among these, an alkyl group having 1 to 8 carbon atoms is preferable, and an alkyl group having 1 to 4 carbon atoms is more preferable. More specifically, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or an n-butyl group is preferable, a methyl group or an ethyl group is more preferable, and an ethyl group is particularly preferable. Here, the effective NCO content is an isocyanate content (mass%) that is potentially present with respect to the total amount (100% by mass) of the blocked isocyanate composition.

Specific examples of the β-ketoester compound include, but are not limited to, methyl acetoacetate, ethyl acetoacetate, methyl isobutanoyl acetate, ethyl isobutanoyl acetate, and acetylacetone. Among them, methyl acetoacetate, ethyl acetoacetate, methyl isobutanoyl acetate, and ethyl isobutanoyl acetate are preferable. More preferably, it is methyl acetoacetate and ethyl acetoacetate, and even more preferably ethyl acetoacetate. The β-ketoester compounds shown above can be used alone or in combination of two or more.

Examples of the β-ketoester compound include isopropyl acetate, n-propyl acetoacetic acid, t-butyl acetoacetic acid, n-butyl acetoacetic acid, and phenyl acetate.

From the viewpoint of low-temperature curability and suppression of seizure yellowing, the isocyanate group blocked by the β-ketoester compound is preferably 50 equivalent% or less, more preferably 40 equivalent% or less, and 30 equivalent% or less of the isocyanate group contained in the triisocyanate. Equivalent% or less is particularly preferable, and 20 equivalent% or less is particularly preferable.

From the viewpoint of more reliably achieving the desired action and effect of the present invention, the above-mentioned malonic acid diester compound is preferably diethyl malonate, and the above-mentioned β-ketoester compound is preferably an acetoacetic acid ester compound. , Ethyl acetoacetate is more preferred.

In the blocking agent of the present embodiment, the molar ratio of the malonic acid diester compound to the β-ketoester compound is not particularly limited, but is preferably more than 1.0. The molar ratio is more preferably 1.5 or more, particularly preferably 2.0 or more, and particularly preferably 3.0 or more.
The molar ratio is preferably 50 or less, more preferably 33 or less, particularly preferably 20 or less, and even more preferably 10 or less.
When the molar ratio exceeds the above lower limit value, the low temperature curability tends to be improved. On the other hand, when the molar ratio is not more than the above upper limit value, the crystallinity at low temperature tends to be suppressed.

The blocking agent of the present embodiment may further contain a blocking agent other than the above-mentioned malonic acid diester compound and β-ketoester compound (hereinafter, also referred to as “other blocking agent”). Specific examples of the other blocking agent are not particularly limited, but for example, a compound having one active hydrogen in the molecule is preferable. The compound having one active hydrogen in the molecule is not particularly limited, and for example, active methylene-based, mercaptan-based, acid amide-based, acidimide-based, imidazole-based, and urea-based compounds other than malonic acid diester compound and β-ketoester compound. , Oxime-based, amine-based, imide-based, and pyrazole-based compounds.

In addition, examples of other blocking agents include alcohol-based, alkylphenol-based, and phenol-based compounds.
More specific other blocking agents include (1) active oxime compounds other than malonic acid diester compounds and β-ketoester compounds; acylketone compounds such as acetylacetone, (2) mercaptans; butyl mercaptans, dodecyl mercaptans, etc., (3) acids. Amid-based; acetanilide, acetate amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc., (4) acid-imide-based; succinateimide, maleateimide, etc., (5) imidazole-based; imidazole, 2-methylimidazole Etc., (6) urea-based; urea, thiourea, ethylene urea, etc., (7) oxime-based; formaldehyde, acetoaldoxime, acetoxime, methylethylketooxime (hereinafter abbreviated as MEKO), cyclohexanone oxime, etc., (8) ) Amines; diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, diisobutylamine, di (2-butylamine), di (t-butyl) amine, dicyclohexylamine, N-t-butylcyclohexyl Amine, 2-methylpiperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, etc., (9) oxime-based; ethyleneimine, polyethyleneimine, etc., (10) pyrazole-based; pyrazole, 3- Examples thereof include methylpyrazole and 3,5-dimethylpyrazole.

Among these, other preferable blocking agents are not particularly limited, but at least selected from active methylene-based and pyrazole-based blocking agents other than oxime-based, amine-based, acid amide-based, malonic acid diester compounds and β-ketoester compounds. It is one kind, more preferably at least one kind selected from active methylene-based and pyrazole-based blocking agents other than oxime-based, malonic acid diester compound and β-ketoester compound, and more preferably malonic acid diester compound and β. It is at least one selected from active methylene-based blocking agents other than ketoester compounds.

<Manufacturing method of blocked isocyanate composition>
A method for producing the blocked isocyanate composition of the present embodiment will be described. The method for producing a blocked isocyanate composition of the present embodiment is a first step of obtaining a blocked isocyanate from a triisocyanate and a blocking agent such as a malonic acid diester compound, followed by the obtained blocked isocyanate and a monoalcohol (1). It has two steps, a second step of causing a transesterification reaction with a valent alcohol compound).

In the first step of the present production method, a blocking agent such as a malonic acid diester compound may be reacted with triisocyanate at the same time, and after reacting either blocking agent with the triisocyanate first. , The other blocking agent may be reacted.

In the blocking reaction (reaction between triisocyanate and blocking agent) in the present embodiment, it is preferable to react so as to block all isocyanate groups of triisocyanate. From this point of view, the molar ratio of the blocking agent to the isocyanate group in triisocyanate ((total number of moles of blocking agent) / (number of moles of isocyanate group in triisocyanate)) is 1.0 or more and 1.5 or less. preferable. The lower limit of the molar ratio is more preferably 1.015, particularly preferably 1.03 or more, and even more preferably 1.045 or more.
The upper limit of the molar ratio is more preferably 1.35, particularly preferably 1.2 or less, and even more preferably 1.1 or less. By setting the lower limit of the molar ratio to the above specific value, the low temperature curability of the blocked isocyanate tends to be more reliably exhibited. On the other hand, by setting the upper limit of the molar ratio to the above-mentioned specific value or less, it tends to be possible to suppress a decrease in dryness after painting.

The reaction in the first step can be carried out with or without the presence of a solvent. When a solvent is used, it is preferable to use a solvent that is inert to the isocyanate group. Specific examples of the solvent are not particularly limited, but for example, aromatic hydrocarbons such as toluene and xylene; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; ethyl acetate, n-butyl acetate, cellosolve acetate and the like. Esters: A solvent can be appropriately selected and used from the group of ethers such as propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether according to the purpose and application. These solvents may be used alone or in combination of two or more.

A reaction catalyst (hereinafter, also referred to as “blocking reaction catalyst”, simply referred to as “catalyst”) can be used in the blocking reaction of the first step. Specific reaction catalysts are not particularly limited, and examples thereof include organometallic salts such as tin, zinc, and lead; metal alcoholates; and tertiary amines.

The blocking reaction catalyst is preferably a basic compound, for example, a metal alcoholate such as sodium methylate, sodium ethylarat, sodium phenolate or potassium methylate; or tetraalkylammonium such as tetramethylammonium, tetraethylammonium or tetrabutylammonium. Hydrooxides and organic weak salts such as acetates, octylates, myristates, benzoates; alkali metal salts of alkylcarboxylic acids such as acetic acid, caproic acid, octyl acid, myristic acid; acetic acid, caproic acid , Metal salts of alkylcarboxylic acids such as octylic acid and myristic acid such as tin, zinc and lead; aminosilyl group-containing compounds such as hexamethylene disilazane; hydroxides of alkali metals such as lithium, sodium and potassium. ..

The amount of the catalyst added is not limited, but is generally preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.05% by mass or more and 3% by mass or less, and 0.1% by mass or more with respect to triisocyanate. 2% by mass or less is particularly preferable.
When the amount of the catalyst added is reduced, the remaining amount of isocyanate groups that are not blocked during the blocking reaction tends to increase. The reaction between the triisocyanate and a blocking agent such as a malonic acid diester compound can be carried out regardless of the presence or absence of a solvent.

When the reaction catalyst used may adversely affect the physical properties of the paint or coating film, it is preferable to inactivate the reaction catalyst with an acidic compound or the like. Specific examples of the acidic compound in this case are not particularly limited, but for example, inorganic acids such as hydrochloric acid, phosphite, and phosphoric acid; methanesulfonic acid, p-toluenesulfonic acid, p-toluenesulfonic acid methyl ester, and p-toluene. Sulphonic acid such as ethyl sulfonic acid or a derivative thereof; monoethyl phosphate, diethyl phosphate, monoisopropyl phosphate, diisopropyl phosphate, monobutyl phosphate, dibutyl phosphate, mono (2-ethylhexyl) phosphate, di (2-ethylhexyl) phosphate, monoisodecyl phosphate, Examples thereof include diisodecyl phosphate, oleyl acid phosphate, tetracosyl acid phosphate, ethyl glycol acid phosphate, butyl pyrophosphate, and butyl phosphite. These acidic compounds can be used alone or in combination of two or more.

The reaction temperature of the first step is preferably −20 ° C. or higher and 150 ° C. or lower, more preferably 0 ° C. or higher and 120 ° C. or lower, and particularly 40 ° C. or higher and 100 ° C. or lower, from the viewpoint of suppressing side reactions and reaction efficiency. preferable. By carrying out the reaction at a reaction temperature of the above upper limit or less, side reactions can be suppressed, and the remaining amount of isocyanate groups that are not blocked during the blocking reaction tends to increase. Further, by carrying out the reaction at a reaction temperature equal to or higher than the above lower limit value, the reaction rate tends to be maintained high.

The reaction time between the triisocyanate and the blocking agent such as the malonic acid diester compound can generally be 0.1 hour or more and 6 hours or less, but from the viewpoint of optimizing the amount of urethane bond structure to be produced, 0. It is preferably 5 hours or more and 4 hours or less. When the reaction time is shortened, the remaining amount of isocyanate groups that are not blocked during the blocking reaction tends to increase.

Further, the reaction temperature and reaction time are preferably set to, for example, 50 ° C. or higher and 180 ° C. or lower, 10 minutes or longer and 480 minutes or lower.
Next, the second step will be described. The second step is a step of reacting the blocked isocyanate obtained in the first step with the monohydric alcohol compound.

The blocked isocyanate composition of the present embodiment contains a blocked isocyanate composition and a monohydric alcohol compound in order to improve storage stability when blended with at least one selected from the group consisting of polyols, polyamines and alkanolamines. It is preferable to carry out the second step as a step of mixing and reacting the two.

The mixing temperature of the second step is preferably −20 ° C. or higher and 150 ° C. or lower, more preferably 0 ° C. or higher and 120 ° C. or lower, and particularly preferably 40 ° C. or higher and 100 ° C. or lower. By carrying out the reaction at a mixing temperature of 150 ° C. or lower, side reactions tend to be suppressed. Further, the mixing time tends to be shortened by carrying out the reaction at a mixing temperature of −20 ° C. or higher.

<Other compounds>
The blocked isocyanate composition of the present embodiment contains one or more compounds selected from the group consisting of unsaturated bond-containing compounds, inert compounds, metal atoms, basic amino compounds, and carbon dioxide, based on the blocked isocyanate compound. It is preferable to contain 0.0 mass ppm or more and 1.0 × 10 ⁴ mass ppm or less from the viewpoint of preventing coloration during long-term storage and improving long-term storage stability. The lower limit of the content range is more preferably 3.0 mass ppm or more, further preferably 5.0 mass ppm or more, further preferably 10 mass ppm or more, and the content. The upper limit of the range is more preferably 5.0 × 10 ³ mass ppm or less, further preferably 3.0 × 10 ³ mass ppm or less, and 1.0 × 10 ³ mass ppm or less. Even more preferable.

The unsaturated bond-containing compound of the present embodiment is preferably a compound in which the unsaturated bond is a carbon-carbon unsaturated bond, a carbon-nitrogen unsaturated bond, or a carbon-oxygen unsaturated bond. is there. From the viewpoint of compound stability, the unsaturated bond is preferably a double bond compound, with a carbon-carbon double bond (C = C) or a carbon-oxygen double bond (C = O). More preferred. Moreover, it is preferable that the carbon atom constituting the compound is bonded to three or more atoms.
In general, the carbon-carbon double bond may be a carbon-carbon double bond constituting an aromatic ring, but the unsaturated bond contained in the unsaturated bond-containing compound of the present embodiment is It does not contain carbon-carbon double bonds that make up the aromatic ring.
Examples of the compound having a carbon-oxygen double bond include a carbonic acid derivative. Examples of the carbonic acid derivative include a urea compound, a carbonic acid ester, an N-unsubstituted carbamic acid ester, and an N-substituted carbamic acid ester.

The Inactive compound of the present embodiment is classified into the following compounds A to G.
The hydrocarbon compound is in compounds A and B, the ether compound and sulfide compound are in the following compounds C to E, and the halogenated hydrocarbon compound is in the following compound F. Silicon-containing hydrocarbon compound, silicon-containing ether compound and silicon-containing sulfide compound Are classified into the following compounds G, respectively. The compounds A to G listed here do not contain an unsaturated bond other than the aromatic ring, and do not contain the above-mentioned compounds having an unsaturated bond.
Compound A: An aliphatic hydrocarbon compound having a linear, branched or cyclic structure.
Compound B: An aromatic hydrocarbon compound that may be substituted with an aliphatic hydrocarbon group.
Compound C: A compound having an ether bond or a sulfide bond and an aliphatic hydrocarbon group, in which the same or different aliphatic hydrocarbon compounds are bonded via an ether bond or a sulfide bond.
Compound D: A compound having an ether bond or a sulfide bond and an aromatic hydrocarbon group, in which the same or different aromatic hydrocarbon compounds are bonded via an ether bond or a sulfide bond.
Compound E: A compound having an ether bond or a sulfide bond, an aliphatic hydrocarbon group, and an aromatic hydrocarbon group.
Compound F: A halide in which at least one hydrogen atom constituting an aliphatic hydrocarbon compound or at least one hydrogen atom constituting an aromatic hydrocarbon compound is replaced with a halogen atom.
Compound G: A compound in which some or all of the carbon atoms of the above compounds A to E are replaced with silicon atoms.

The metal atom of the present embodiment may exist as a metal ion or as a single metal atom. It may be one kind of metal atom, or a plurality of kinds of metal atoms may be combined. As the metal atom, a metal atom having a divalent to tetravalent valence is preferable, and among them, one or more kinds of metals selected from iron, cobalt, nickel, zinc, tin, copper and titanium are more preferable.

The basic amino compound of the present embodiment is a derivative of ammonia, in which one hydrogen is substituted with an alkyl group or an aryl group (primary), a compound in which two hydrogens are substituted (secondary), and three. There are always substituted compounds (tertiary). The basic amino compounds that can be preferably used in the present invention are secondary and tertiary amino compounds, and aliphatic amines, aromatic amines, heterocyclic amines, and basic amino acids can be preferably used.

Carbon dioxide may be dissolved in isocyanate at normal pressure, or may be placed in a pressure vessel and dissolved in a pressurized state. Since the use of carbon dioxide containing water may cause hydrolysis of isocyanate, it is preferable to control the amount of water contained in carbon dioxide as necessary.

The halogen atom content of the blocked isocyanate composition of the present embodiment is preferably 1.0 × 10 ² mass ppm or less from the viewpoint of preventing coloration. The halogen atom is not particularly limited, but chlorine and / or bromine is preferable, and it may be at least one ion and / or compound selected from chlorine ion, bromine ion, hydrolyzable chlorine, and hydrolyzable bromine. More preferred. Examples of the hydrolyzable chlorine include a carbamoyl chloride compound in which hydrogen chloride is added to an isocyanate group, and examples of the hydrolyzable bromine include a carbamoyl bromide compound in which hydrogen bromide is added to an isocyanate group.

<One-component paint composition>
The blocked isocyanate composition of the present embodiment can also be suitably used as a curing agent or the like for a one-component coating composition. That is, it can be a one-component coating composition containing the blocked isocyanate composition of the present embodiment. The resin component of the one-component coating composition preferably contains a compound having two or more active hydrogens having reactivity with an isocyanate group in the molecule. Examples of the compound having two or more active hydrogens in the molecule include polyols, polyamines, polythiols and the like. Among these, polyol is preferable. Specific examples of the polyol include polyester polyol, polyether polyol, acrylic polyol, polyolefin polyol, fluorine polyol and the like.
The one-component coating composition using the blocked isocyanate composition of the present embodiment can be used for both solvent-based and water-based coatings.

In the case of a solvent-based one-component coating composition, a resin containing a compound having two or more active hydrogens in the molecule, or a solvent-diluted product thereof, and other resins, catalysts, pigments, if necessary, can be used. The blocked isocyanate composition of the present embodiment is added as a curing agent to an additive such as a leveling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, and a surfactant, and if necessary. A solvent-based coating composition can be obtained by further adding a solvent to adjust the viscosity and then stirring by hand or using a stirring device such as Magellar.

In the case of an aqueous-based one-component coating composition, an aqueous dispersion of a resin containing a compound having two or more active hydrogens in the molecule, or a water-soluble substance, and other resins, catalysts, etc., if necessary. The blocked isocyanate composition of the present embodiment is added as a curing agent to an additive such as a pigment, a leveling agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a plasticizer, and a surfactant, and is required. Therefore, a water-based coating composition can be obtained by further adding water or a solvent and then forcibly stirring with a stirring device.

The polyester polyol is, for example, a single or a mixture of dibasic acids such as succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, and carboxylic acids such as 1,4-cyclohexanedicarboxylic acid. , Ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, trimethylolpropane, glycerin, pentaerythritol, 2-methylolpropanediol, It can be obtained by subjecting a polyhydric alcohol such as ethoxylated trimethylolpropane alone or a mixture to a condensation reaction. For example, the condensation reaction can be carried out by combining the above components and heating at about 160-220 ° C. Further, for example, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone with a polyhydric alcohol can also be used as the polyester polyol. These polyester polyols can be modified with aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, and polyisocyanates obtained from them. In this case, an aliphatic diisocyanate, an alicyclic diisocyanate, and a polyisocyanate obtained from these are particularly preferable from the viewpoint of weather resistance, yellowing resistance, and the like. When used as a water-based base paint, it is water-soluble or water-dispersible by leaving a part of carboxylic acid such as dibasic acid left and neutralizing it with a base such as amine or ammonia. It can be a resin.

Examples of the polyether polyol include, for example, a hydroxide (lithium, sodium, potassium, etc.), a strongly basic catalyst (alcolate, alkylamine, etc.), and a composite metal cyan compound complex (metal) in a single or mixture of polyvalent hydroxy compounds. Random or block addition of alkylene oxides (ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide, etc.) alone or in admixture to polyvalent hydroxy compounds using porphyrin, zinc hexacyanocobalate complex, etc.) , The obtained polyether polyols; the polyether polyols obtained by reacting a polyamine compound (ethylenediamine, etc.) with an alkylene oxide; and the so-called polymer polyol obtained by polymerizing acrylamide or the like using these polyether polyols as a medium. Kind and the like.

Examples of the polyvalent hydroxy compound include (i) diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol and the like, and (ii) for example, erythritol, D-trateol, L-arabinitol, ribitol, xylitol, sorbitol, etc. Sugar-alcohol compounds such as mannitol, galactitol, ramnitol, (iii) for example, monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, ribodesource, (iv) for example, trehalose. , Disaccharides such as sucrose, maltose, cellobiose, gentiobiose, lactose, melibiose, (v) trisaccharides such as raffinose, gentianose, meletitose, (vi) tetrasaccharides such as stakiose, and the like.

The acrylic polyol can be obtained, for example, by copolymerizing a polymerizable monomer having one or more active hydrogens in one molecule and another monomer copolymerizable with the polymerizable monomer.

The acrylic polyol is, for example, acrylic acid esters having active hydrogen (-2-hydroxyethyl acrylate, -2-hydroxypropyl acrylate, -2-hydroxybutyl acrylate, etc.), or methacrylic acid esters having active hydrogen. (-2-Hydroxyethyl methacrylate, -2-hydroxypropyl methacrylate, -2-hydroxybutyl methacrylate, -3-hydroxypropyl methacrylate, -4-hydroxybutyl methacrylate, etc.), glycerin, trimethylolpropane, etc. (Meth) acrylic acid esters having polyvalent active hydrogen such as triol (meth) acrylic acid monoester; polyether polyols (polyethylene glycol, polypropylene glycol, polybutylene glycol, etc.) and the above-mentioned active hydrogen (meth). ) Monoether with acrylic acid esters; adducts of glycidyl (meth) acrylate and monobasic acids such as acetic acid, propionic acid, p-tert-butylbenzoic acid; (meth) acrylic acid ester having the above-mentioned active hydrogen. As an essential component, one or more selected from the group consisting of additives obtained by ring-opening polymerization of lactones (ε-caprolactam, γ-valerolactone, etc.) with active hydrogen of the same kind as necessary (meth) Acrylic acid esters (methyl acrylate, ethyl acrylate, isopropyl acrylate, -n-butyl acrylate, -2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, -n-butyl methacrylate, Isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, glycidyl methacrylate, etc.), unsaturated carboxylic acids (acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc.), unsaturated amides (acrylamide) , N-methylolacrylamide, diacetoneacrylamide, etc.), or vinyl monomers having a hydrolyzable silyl group (vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ- (meth) acrylopropyltrimethoxysilane, etc.), and others. It can be obtained by copolymerizing at least one selected from the group consisting of polymerizable monomers (styrene, vinyl toluene, vinyl acetate, acrylic nitrile, dibutyl fumarate, etc.) by a conventional method.

For example, the above monomer component is solution-polymerized in the presence of a known radical polymerization initiator such as a peroxide or an azo compound, and diluted with an organic solvent or the like as necessary to obtain an acrylic polyol. Can be done. When an aqueous-based acrylic polyol is obtained, it can be produced by a known method such as a method of solution-polymerizing an olefinically unsaturated compound to convert it into an aqueous layer or emulsion polymerization. In that case, water solubility or water dispersibility can be imparted by neutralizing an acidic portion such as a carboxylic acid-containing monomer such as acrylic acid or methacrylic acid or a sulfonic acid-containing monomer with amine or ammonia.

The fluorine polyol is a polyol containing fluorine in the molecule, and for example, fluoroolefins, cyclovinyl ethers, hydroxyalkyl vinyl ethers disclosed in JP-A-57-34107, JP-A-61-215311 and the like. Examples thereof include copolymers such as monocarboxylic acid vinyl ester.

The hydroxyl value of the polyol is not particularly limited, but is preferably 10 mgKOH / g or more and 200 mgKOH / g or less. Among them, the lower limit is more preferably 20 mgKOH / g, and particularly preferably 30 mgKOH / g or more. The acid value of the polyol is preferably 0 mgKOH / g or more and 30 mgKOH / g or less. The hydroxyl value and acid value can be measured according to JIS K1557.

Among the above, as the polyol, an acrylic polyol is preferable from the viewpoint of weather resistance, chemical resistance, and hardness, and a polyester polyol is preferable from the viewpoint of mechanical strength and oil resistance.

The equivalent ratio (NCO / OH ratio) of the isocyanate groups of the blocked isocyanate composition of the present embodiment to the hydroxyl groups of the compound having two or more active hydrogens in the molecule is preferably 0.2 or more and 5.0 or less. It is more preferably 0.4 or more and 3.0 or less, and particularly preferably 0.5 or more and 2.0 or less. When the equivalent amount ratio is equal to or higher than the above lower limit value, a tougher coating film can be obtained. When the equivalent amount ratio is not more than the above upper limit value, the smoothness of the coating film can be further improved.

A melamine-based curing agent such as a completely alkyl type, a methylol type alkyl, or an imino group type alkyl can be added to the one-component coating composition, if necessary.

The compound having two or more active hydrogens in the molecule, the blocked isocyanate composition of the present embodiment, and the one-component coating composition can all be used by mixing with an organic solvent. The organic solvent preferably does not have a functional group that reacts with a hydroxyl group and an isocyanate group. Further, it is preferable to be compatible with the blocked isocyanate composition. Examples of such organic solvents include ester compounds, ether compounds, ketone compounds, aromatic compounds, ethylene glycol dialkyl ether compounds, polyethylene glycol dicarboxylate compounds, and hydrocarbon solvents that are generally used as paint solvents. , Aromatic solvents and the like.

The compound having two or more active hydrogens in the molecule, the blocked isocyanate composition of the present embodiment, and the one-component coating composition are all within a range that does not impair the effects of the present embodiment according to the purpose and application thereof. Therefore, various additives used in the art such as catalysts, pigments, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, plasticizers, and surfactants can be mixed and used.

Examples of catalysts for promoting curing include metal salts such as dibutyltin dilaurate, tin 2-ethylhexanoate, zinc 2-ethylhexanoate, cobalt salt, etc .; triethylamine, pyridine, methylpyridine, benzyldimethylamine, N, N- Examples thereof include tertiary amines such as dimethylcyclohexylamine, N-methylpiperidin, pentamethyldiethylenetriamine, N, N'-endoethylenepiperazine, N, N'-dimethylpiperazine, and the like.

The one-component coating composition using the blocked isocyanate composition of the present embodiment as a curing agent can be used as a coating material for roll coating, curtain flow coating, spray coating, bell coating, electrostatic coating and the like. For example, it is useful as a primer or a top coat paint for materials such as metals (steel plates, surface-treated steel plates, etc.), plastics, wood, films, and inorganic materials. It is also useful as a paint for imparting cosmetic properties, weather resistance, acid resistance, rust prevention properties, chipping resistance, etc. to pre-coated metals including rust-preventive steel sheets, automobile coatings, and the like. It is also useful as a urethane raw material for adhesives, pressure-sensitive adhesives, elastomers, foams, surface treatment agents and the like.

<Coating film>
The present invention is a coating film obtained by curing the above-mentioned one-component coating composition of the present invention.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. However, Example 6 is a reference example.

(Physical properties 1) Effective NCO content (mass%)
The effective NCO content of blocked isocyanate was determined as follows. The effective NCO content (mass%) here is for quantifying the amount of blocked isocyanate groups present in the blocked isocyanate composition after the blocking reaction and which can be involved in the crosslinking reaction, and is the mass of the isocyanate groups. Expressed as% and calculated by the following formula.
{(Solid content of blocked isocyanate composition (mass%)) x (mass of polyisocyanate used in reaction x isocyanate group content of precursor polyisocyanate)} / (resin of blocked isocyanate composition after blocking reaction) mass)
When the sample was diluted with a solvent or the like, the value in the diluted state is described.

(Physical properties 2) Solid content concentration (mass%)
After precisely weighing an aluminum dish with a bottom diameter of 38 mm, the blocked isocyanate composition of Example or Comparative Example is precisely weighed with about 1 g placed on the aluminum dish (W1), and the blocked isocyanate composition is adjusted to a uniform thickness. , 105 ° C. for 1 hour. After the aluminum dish reached room temperature, the blocked isocyanate composition remaining on the aluminum dish was precisely weighed (W2).
Solid content concentration = W2 / W1 × 100

(Evaluation 1) Low-temperature crystallinity The obtained blocked isocyanate composition was stored at 5 ° C. The appearance at that time was confirmed and evaluated according to the following criteria.
⊚: Not crystallized even after 1 month ○: Crystallized within 1 month over 1 week Δ: Crystallized within 1 week over 1 day ×: Crystallized within 1 day

(Evaluation 2) Low-temperature curability "Setalux 1152" (acrylic polyol, trade name manufactured by Nuplex Resins, hydroxyl value 138 mgKOH / resin g, solid content concentration 51% by mass) and blocked isocyanate composition were combined with NCO / OH = 1. Formulate to 0, and add butyl acetate to Ford Cup No. The temperature was adjusted to 20 seconds / 23 ° C. in 4 to obtain an α-paint solution.
The obtained α-paint solution was coated on a glass plate with an air spray gun so as to have a dry film thickness of 40 μm, dried at 23 ° C. for 30 minutes, and then baked at 90 ° C. for 20 minutes to obtain a cured coating film.
After baking the obtained cured coating film, the König hardness was measured at 20 ° C. with a pendulum type hardness tester manufactured by BYK Chemie, and evaluated according to the following criteria.
⊚: König hardness is 80 or more ○: König hardness is 70 or more and less than 80,
Δ: König hardness is 60 or more and less than 70 ×: König hardness is less than 60

(Evaluation 3) Anti-seizure yellowing The α paint solution obtained in (Evaluation 2) above was applied to a glass plate with an air spray gun so that the dry film thickness was 40 μm, and at 140 ° C for 30 minutes, and at 160 ° C. A total of two bakings were performed for 30 minutes. The obtained coating film was left at 20 ° C. for 1 hour, and the difference between the coated plate b value measured and the glass plate b value before baking using a color difference meter (digital automatic color difference meter manufactured by Suga Test Instruments Co., Ltd.) ( Δb) was defined as yellowing resistance.
◯: Δb is less than 1.0 Δ: Δb is 1.0 or more and less than 1.5 ×: Δb is 1.5 or more

(Evaluation 4) Adhesion to the upper coating film The α-paint solution obtained in (Evaluation 2) above was applied to a mild steel plate with an air spray gun so that the dry film thickness was 40 μm, and dried at 23 ° C. for 30 minutes. , 90 ° C. for 20 minutes to obtain an α coating film layer 1. The adhesion test of the α coating layer 1 with the mild steel plate was performed according to JIS K5600-5-6. As a result, no peeling was observed, including some floating.
70 parts of "Setalux 1767" (acrylic polyol, trade name manufactured by Nuplex Resins, hydroxyl value 150 mgKOH / resin g, solid content 65% by mass), hexamethoxymethylated melamine resin "Simel (registered trademark) 300" manufactured by Nippon Cytec Co., Ltd. After mixing 30 parts by mass and 1 part by mass of p-toluenesulfonic acid, with butyl acetate, Ford Cup No. The temperature was adjusted to 20 seconds / 23 ° C. in 4 to obtain a β-paint solution.
Separately, the α-paint solution obtained in the above (evaluation 2) was applied to a mild steel plate with an air spray gun so that the dry film thickness was 40 μm, dried at 23 ° C. for 30 minutes, and then baked at 90 ° C. for 20 minutes. The α coating layer 2 was obtained. The α coating film layer 2 is coated with a β coating solution with an air spray gun so as to have a dry film thickness of 40 μm, dried at 23 ° C. for 30 minutes, and then baked at 140 ° C. for 30 minutes to have an α layer and a β layer. A layer coating was obtained. The adhesion test of the obtained multi-layer coating film was performed according to JIS K5600-5-6. It was evaluated according to the following criteria.
◯: No peeling coating film, no floating △: Less than half of the peeling coating film available ×: More than half of the release coating film available

(Synthesis Example 1) Synthesis of NTI In a four-necked flask equipped with a stirrer, a thermometer, and a gas introduction tube, 1060 g of 4-aminomethyl-1,8-octamethylenediamine (hereinafter referred to as triamine) is converted to 1500 g of methanol. It was dissolved, and 1800 ml of 35% concentrated hydrochloric acid was gradually added dropwise to the solution while cooling. Methanol and water were removed under reduced pressure, concentrated, and dried at 60 ° C./5 mmHg for 24 hours to obtain a white solid triamine hydrochloride. 650 g of the obtained triamine hydrochloride was suspended in 5000 g of o-dichlorobenzene as a fine powder, the temperature of the reaction solution was raised while stirring, and when the temperature reached 100 ° C., phosgene began to be blown at a rate of 200 g / Hr. The temperature was further raised to 180 ° C., and phosgene was continuously blown for 12 hours. Dissolved phosgene and solvent are distilled off under reduced pressure, and then vacuum distillation is performed to obtain a colorless and transparent 4-isocyanate methyl-1,8-octanemethylene diisocyanate having a boiling point of 161 to 163 ° C./1.2 mmHg (hereinafter referred to as "NTI"). 420 g was obtained. The NCO content of this product was 50.0% by weight.

(Synthesis Example 2) Synthesis of LTI 122.2 g of ethanolamine, 100 ml of o-dichlorobenzene and 420 ml of toluene are placed in a 4-necked flask equipped with a stirrer, a thermometer and a gas introduction tube, and ice-cooled hydrogen chloride gas is added. It was introduced and converted ethanolamine to hydrochloride. Next, 182.5 g of lysine hydrochloride was added, the reaction solution was heated to 80 ° C., ethanolamine hydrochloride was dissolved, and hydrogen chloride gas was introduced to obtain lysine dihydrochloride. Further, hydrogen chloride gas was passed at 20 to 30 ml / min, the reaction solution was heated to 116 ° C., and this temperature was maintained until water stopped distilling. The resulting reaction mixture was recrystallized in a mixed solution of methanol and ethanol to obtain 165 g of lysine β-aminoethyl ester trihydrochloride. 100 g of this lysine β-aminoethyl ester trihydrochloride was suspended in 1200 ml of o-dichlorobenzene as a fine powder, the temperature of the reaction solution was raised while stirring, and when the temperature reached 120 ° C., phosgene was added at 0.4 mol / hour. The blowing was started at a rate, held for 10 hours, and then the temperature was raised to 150 ° C. The suspension was almost dissolved. After cooling, the mixture was filtered, dissolved phosgene and a solvent were distilled off under reduced pressure, and then vacuum distillation was performed to obtain 80.4 g of colorless and transparent LTI having a boiling point of 155 to 157 ° C./0.022 mmHg. The NCO content of this product was 47.1% by weight.

(Synthesis Example 3) Synthesis of GTI 275 g of glutamate hydrochloride, 800 g of ethanolamine hydrochloride and 150 ml of toluene are placed in a 4-necked flask equipped with a stirrer, thermometer and gas introduction tube, and water is blown while blowing hydrogen chloride gas. The mixture was heated under reflux at 110 ° C. for 24 hours until it stopped azeotropically boiling. The resulting reaction mixture was recrystallized in a mixed solution of methanol and ethanol to obtain 270 g of bis (2-aminoethyl) glutamate trihydrochloride. 85 g of this bis (2-aminoethyl) glutamate trihydrochloride was suspended in 680 g of o-dichlorobenzene, the temperature of the reaction solution was raised while stirring, and when the temperature reached 135 ° C., phosgene was added at a rate of 0.8 mol / hour. GTI was obtained by filtering the reaction product, concentrating it under reduced pressure, and further purifying it in a thin-film evaporator. The NCO content was 39.8% by weight.

(Example 1) Synthesis of B-1 The inside of a four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen blowing tube is made into a nitrogen atmosphere, and NTI is 100 parts by mass, diethyl malonate is 201 parts by mass, and acetate. 49 parts by mass of n-butyl was charged, 1.0 part by mass of a 28% sodium methylate solution was added, and the reaction was carried out at 60 ° C. for 6 hours. Then, 49 parts by mass of 1-butanol was added, and stirring was continued at that temperature for 2 hours. 1.0 part by mass of monophosphate (2-ethylhexyl) was added thereto to obtain a blocked isocyanate composition B-1 having an effective NCO content of 12.5% and a solid content concentration of 75% by mass. The obtained blocked isocyanate composition B-1 was evaluated in (Evaluation 1) to (Evaluation 4) described above. The results obtained are shown in Table 1.
In Table 1 below, "TPA-100" is an HDI-based polyisocyanate "Duranate TPA-100" (trade name: manufactured by Asahi Kasei Corporation, isocyanurate type).

(Examples 2 to 10 and Comparative Examples 1 to 3)
Blocked Isocyanate Compositions B-2 to B-10 and B-11 to B- in the same manner as in Example 1 except that the formulations shown in Table 1 are used in Examples 2 to 10 and Comparative Examples 1 to 3. I got 13. Table 1 shows the physical property values and evaluation results of the obtained blocked isocyanate composition.

(Example 11)
0.03 g of 2,2,4-trimethylpentane was added to 300 g of NTI to obtain an isocyanate composition. A blocked isocyanate composition was obtained by the same operation as in Example 1.
The evaluation results of this blocked isocyanate composition were the same as in Example 1.

(Example 12)
0.03 g of hexadecane was added to 300 g of NTI to obtain an isocyanate composition. A blocked isocyanate composition was obtained by the same operation as in Example 1.
The evaluation results of this blocked isocyanate composition were the same as in Example 1.

(Synthesis Example 4)
The inside of a 4-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen blowing tube is made into a nitrogen atmosphere, 20 g of NTI is charged, heated to 60 ° C., 7.7 g of methanol is added, and 4 while stirring. After holding for a long time, N-substituted carbamic acid ester C-1 was obtained.

(Example 14)
0.03 g of N-substituted carbamic acid ester C-1 was added to 300 g of NTI to obtain an isocyanate composition. A blocked isocyanate composition was obtained by the same operation as in Example 1.
The evaluation results of this blocked isocyanate composition were the same as in Example 1.

As shown in the above results, Examples 1 to 10 to which the present invention was applied were excellent in low temperature curability and excellent adhesion to the upper coating film when the coating film was laminated.

The one-component coating composition using the blocked isocyanate composition of the present invention as a curing agent can be used as a coating material for roll coating, curtain flow coating, spray coating, bell coating, electrostatic coating and the like. Further, it can be used as a primer or an intermediate coating paint for metals such as steel plates and surface-treated steel plates, and materials such as plastics, wood, films and inorganic materials. Further, it is also useful as a pre-coated metal containing a rust-preventive steel plate, a paint for imparting heat resistance, cosmetic properties (surface smoothness, sharpness), etc. to automobile coatings and the like. Furthermore, it is also useful as a urethane raw material for adhesives, pressure-sensitive adhesives, elastomers, foams, surface treatment agents and the like.

Claims (5)

The blocking agent contains a blocked isocyanate compound obtained from a triisocyanate compound represented by the following general formula (I) and a blocking agent, and the blocking agent is selected from the group consisting of a malonic acid diester compound represented by the following general formula (II). at least one only containing, isocyanate groups contained in the triisocyanate compound, 80 equivalent% or more is blocked by the malonic acid diester compound, blocked isocyanate composition.

[In the general formula (I), plural Y ¹ are each independently a single bond or a divalent hydrocarbon group having ester structure and / or which may having 1 to 20 carbon atoms contain an ether structure. Plurality of Y ¹ may be different from each other may be the same. R ¹ is a hydrogen atom or a monovalent hydrocarbon group having 1 to 12 carbon atoms. ]

[In the general formula (II), R ² and R ³ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, or a benzyl group. R ² and R ³ may be the same or different. ] The blocked isocyanate composition according to claim 1, wherein the blocking agent further comprises at least one selected from the group consisting of β-ketoester compounds represented by the following general formula (III).

[In the general formula (III), R ⁴ and R ⁵ each independently represent an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group, a phenyl group, or a benzyl group. R ⁴ and R ⁵ may be the same or different. ] The blocked isocyanate composition according to claim 2, wherein the molar ratio of the malonic acid diester compound to the β-ketoester compound exceeds 1.0. A one-component coating composition containing the blocked isocyanate composition according to any one of claims 1 to 3 and a polyol. A coating film obtained by curing the one-component coating composition according to claim 4.