JP6591241B2 - Block polyisocyanate composition, one-pack type coating composition, coating film, and painted article - Google Patents

Description

  The present invention relates to a block polyisocyanate composition, a one-component coating composition, a coating film, and a coated article.

  A polyisocyanate is widely used for baking coating as a heat-crosslinking type curing agent together with a melamine curing agent. 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., polyisocyanates blocked with blocking agents (block polyisocyanates) have attracted attention. Yes.

  Conventionally, oximes, phenols, alcohols, and lactams are known as blocking agents for blocked polyisocyanates.

  As the block polyisocyanate composition capable of lowering the baking temperature, a block polyisocyanate composition containing malonic acid diester as a blocking agent (see, for example, Patent Document 1), diethyl malonate and ethyl acetoacetate as a blocking agent The block polyisocyanate composition (for example, refer patent document 2 and 3) etc. is proposed.

JP 57-121065 A JP-A-8-225630 JP-A-9-255915

  However, since the block polyisocyanate composition formed using the conventional blocking agent generally requires a high baking temperature of 140 ° C. or higher, the energy cost is very high. Moreover, there is a limitation that a block polyisocyanate composition that requires high-temperature baking cannot be used for processing into a plastic having low heat resistance.

  In applications such as painting of new automobiles, a coating layer such as a clear layer may be further laminated on a coating layer using a conventional block polyisocyanate composition. As a 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 less and having good adhesion when laminated is desired.

  On the other hand, although the block polyisocyanate composition disclosed in Patent Documents 1 to 3 can form a crosslinked coating film at a temperature of 100 ° C. or lower, the coating layer using these block polyisocyanate compositions is used. Furthermore, it has a further problem in the adhesion when the coating film is laminated. Moreover, when these block polyisocyanate compositions are used, the compatibility with some polyols may be insufficient.

  Therefore, the present invention provides a block polyisocyanate composition that is excellent in adhesion to an upper layer coating film and excellent in compatibility with a polyol when the coating layer is laminated while maintaining low temperature curability. With the goal.

  As a result of diligent research, the present inventor has surprisingly found that a block polyisocyanate composition containing a specific isocyanate-malonic acid diester bond structure in a specific range ratio retains low-temperature curability while maintaining the upper layer coating. It has been found that the adhesion with the film is remarkably improved and the compatibility with the polyol is excellent, and the present invention has been completed.

（式（Ｉ）中、Ｒ₁及びＲ₂は、各々独立に、炭素数１〜８個のアルキル基、フェニル基、又はベンジル基を示す。）
［２］
前記ブロック剤は、前記マロン酸ジエステル化合物以外のブロック剤をさらに含む、［１］に記載のブロックポリイソシアネート組成物。
［３］
前記ブロック剤において、前記マロン酸ジエステル化合物以外のブロック剤に対する前記マロン酸ジエステル化合物のモル比が、１．０以上である、［２］に記載のブロックポリイソシアネート組成物。
［４］
１価アルコール化合物をさらに含み、
前記ブロックポリイソシアネート組成物のブロックポリイソシアネート基に対する前記１価アルコール化合物のモル比が、０．２以上１０以下である、［１］〜［３］のいずれかに記載のブロックポリイソシアネート組成物。
［５］
［１］〜［４］のいずれかに記載のブロックポリイソシアネート組成物と、ポリオールと、を含む一液型コーティング組成物。
［６］
［５］に記載の一液型コーティング組成物により形成された塗膜。
［７］
［５］に記載の一液型コーティング組成物により塗装された塗装物品。 That is, the present invention has the following configuration.
[1]
A block polyisocyanate obtained from a polyisocyanate derived from at least one diisocyanate selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate, and a blocking agent,
The blocking agent includes a malonic acid diester compound,
The block polyisocyanate composition whose ratio of the methane tetracarbonyl structure shown by following formula (I) with respect to the total amount of an isocyanate-malonic acid diester bond structure is 0.5 mol% or more and 10 mol% or less.

(In formula (I), R ₁ and R ₂ each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a benzyl group.)
[2]
The block polyisocyanate composition according to [1], wherein the blocking agent further includes a blocking agent other than the malonic acid diester compound.
[3]
The block polyisocyanate composition according to [2], wherein in the blocking agent, a molar ratio of the malonic acid diester compound to a blocking agent other than the malonic acid diester compound is 1.0 or more.
[4]
Further comprising a monohydric alcohol compound,
The block polyisocyanate composition according to any one of [1] to [3], wherein a molar ratio of the monohydric alcohol compound to a block polyisocyanate group of the block polyisocyanate composition is 0.2 or more and 10 or less.
[5]
A one-component coating composition comprising the block polyisocyanate composition according to any one of [1] to [4] and a polyol.
[6]
The coating film formed with the one-pack type coating composition as described in [5].
[7]
[5] A coated article coated with the one-component coating composition according to [5].

  According to the block polyisocyanate composition according to the present invention, the low-temperature curability is maintained, the adhesiveness with the upper layer coating film is excellent, and the compatibility with the polyol is also excellent.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.

[Block polyisocyanate composition]
The block polyisocyanate composition of the present embodiment includes a block polyisocyanate obtained from a polyisocyanate derived from at least one diisocyanate selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate, and a blocking agent. . The blocking agent contains a malonic acid diester compound. Furthermore, in the block polyisocyanate composition, the ratio of the methane tetracarbonyl structure represented by the following formula (I) to the total amount (100 mol%) of the isocyanate-malonic acid diester bond structure is 0.5 mol% or more and 10 mol%. It is as follows.

式（Ｉ）中のＲ₁、及びＲ₂は、各々独立に、炭素数１〜８個のアルキル基、フェニル基、又はベンジル基を示す。Ｒ₁、及びＲ₂は同一でも構わないし、異なっていても構わない。Ｒ₁、及びＲ₂が、各々独立に、炭素数８以下のアルキル基、フェニル基、又はベンジル基を示すメタンテトラカルボニル構造であることで、有効ＮＣＯ含有率の低下が抑制されるとともに、塗料としたときの主剤等との相溶性を良好にすることができる傾向にあり、好ましい。これらの中でも、Ｒ₁、及びＲ₂は、各々独立に炭素数１〜８のアルキル基を示すメタンテトラカルボニル構造であることが好ましく、より好ましくは炭素数１〜４のアルキル基を示すメタンテトラカルボニル構造であり、さらに好ましくはエチル基、ｎ−プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基を示すメタンテトラカルボニル構造である。 The block polyisocyanate composition of the present embodiment has a methane tetracarbonyl structure represented by the following formula (I).

R _1, and R ₂ in the formula (I) each independently represents, a 1-8C alkyl group carbon atoms, a phenyl group, or a benzyl group. R ₁ and R ₂ may be the same or different. R ₁ and R ₂ are each independently a methanetetracarbonyl structure having an alkyl group having 8 or less carbon atoms, a phenyl group, or a benzyl group, so that a decrease in the effective NCO content is suppressed, and a paint It tends to be able to improve the compatibility with the main agent and the like, and is preferable. Among these, R _1, and R ₂ is preferably a tetra carbonyl structure an alkyl group having 1 to 8 carbon atoms each independently, more preferably tetra represents an alkyl group having 1 to 4 carbon atoms A carbonyl structure, more preferably a methane tetracarbonyl structure showing an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group.

  In the block polyisocyanate composition, the ratio of the methane tetracarbonyl structure represented by the above formula (I) to the total amount (100 mol%) of the isocyanate-malonic acid diester bond structure is 0.5 mol% or more and 10 mol% or less. . The lower limit of the ratio is preferably 0.7 mol%, more preferably 1.0 mol%, still more preferably 1.5 mol%, still more preferably 2.0 mol%. is there. The upper limit of the ratio is preferably 8.0 mol%, more preferably 6.0 mol%, still more preferably 5.0 mol%, still more preferably 4.0 mol%. is there. When the ratio is 0.5 mol% or more, the coating layer using the block polyisocyanate composition of the present embodiment can further exhibit adhesion to the coated upper layer coating film, and When the ratio is 10 mol% or less, compatibility with the polyol can be maintained. The said ratio can be measured by the method as described in the Example mentioned later.

  The isocyanate-malonic acid diester bond structure indicates a structure in which an isocyanate group and a malonic acid diester are chemically bonded, and examples thereof include a methanetricarbonyl structure (keto form, enol form) and a methanetetracarbonyl structure.

  In this embodiment, by containing a specific range amount of the methanetetracarbonyl structure represented by the formula (I), not only low-temperature curability but also adhesiveness with the upper layer coating film is exhibited, and compatibility with polyol It was surprising that a blocked polyisocyanate composition was also obtained.

  It is preferable that the block polyisocyanate composition of this embodiment further contains a monohydric alcohol compound. In the block polyisocyanate composition, the molar ratio of the monohydric alcohol compound to the block polyisocyanate group in the block polyisocyanate composition is more preferably from 0.2 to 10.

  Although it does not specifically limit as said monohydric alcohol type compound, For example, monohydric alcohol type compounds, such as aliphatic, alicyclic, and aromatic, are mentioned, Among them, it is an aliphatic monohydric alcohol type compound. preferable. Although an aliphatic monohydric alcohol compound is not specifically limited, It is more preferable that it is a C1-C20 monohydric alcohol type compound. Although it does not specifically limit as a C1-C20 monohydric alcohol type compound, For example, methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, t-butanol, 2-ethyl-1-propanol N-amyl alcohol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 2, Examples include saturated alcohols such as 2-dimethyl-1-propanol; ether alcohols such as 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, and 3,6-dioxa-1-heptanol.

  The molar ratio of the monohydric alcohol compound to the blocked isocyanate group contained in the block polyisocyanate composition is more preferably 0.2 or more and 10 or less. The lower limit of the molar ratio is more preferably 0.4, even more preferably 0.7, and still more preferably 1.0. Further, the upper limit value of the molar ratio is more preferably 7.0, still more preferably 5.0, and still more preferably 3.0. When the molar ratio is 0.2 or more, the storage stability when a one-component coating composition is obtained tends to be ensured, and when the molar ratio is 10 or less, the effective NCO content is It tends to be possible to suppress the decrease of

  The solid content concentration of the block polyisocyanate composition is not particularly limited, but is preferably 40% by mass or more and 80% by mass or less, and more preferably 50% by mass or more and 70% by mass or less. When the solid content concentration is 40% by mass or more, the amount of volatilization during baking tends to be reduced, and when the solid content concentration is 80% by mass or less, workability when blending the block polyisocyanate composition is good. Tend to be. In order to obtain a polyisocyanate having a solid content concentration of 40% by mass or more and 80% by mass or less, a solvent may be added before and after the synthesis of the block polyisocyanate composition so as to obtain the solid content concentration. The solid content concentration can be measured by the method described in Examples described later.

  The effective NCO content of the block polyisocyanate composition is not particularly limited, but is preferably 8.0% by mass or more and 20% by mass or less, more preferably 10%, based on the total amount of solid content (100% by mass). It is not less than 15% by mass. When the effective NCO content is 8.0% by mass or more with respect to the total solid content (100% by mass), the crosslinking density after baking tends to be maintained well, and the effective NCO content is 20% by mass. It exists in the tendency which will ensure the smoothness of the coating film after baking by being below. In order to obtain a block polyisocyanate composition having an effective NCO content of 8.0% by mass or more and 20% by mass or less with respect to the total solid content (100% by mass), for example, the NCO content is 15% by mass. A polyisocyanate of 25% by mass or less may be used as a raw material. Effective NCO content rate can be measured by the method as described in the Example mentioned later.

<Polyisocyanate>
The polyisocyanate of this embodiment is derived from at least one diisocyanate selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates.

  Although it does not specifically limit as aliphatic diisocyanate, The thing of carbon number 4.0 or more and 30 or less is preferable, for example, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (henceforth "HDI"), 2 2,4-trimethyl-1,6-diisocyanatohexane, lysine diisocyanate. Among these, HDI is more preferable from the viewpoint of industrial availability. Aliphatic diisocyanates may be used alone or in combination of two or more.

  Although it does not specifically limit as alicyclic diisocyanate, A C8 or more and 30 or less thing is preferable, for example, isophorone diisocyanate (henceforth "IPDI"), 1,3-bis (isocyanatomethyl). ) -Cyclohexane, 4,4′-dicyclohexylmethane diisocyanate, norbornene diisocyanate, and hydrogenated xylylene diisocyanate. Among these, IPDI is more preferable from the viewpoint of weather resistance and industrial availability. An alicyclic diisocyanate may be used independently and may use 2 or more types together.

  The polyisocyanate derived from the above-mentioned diisocyanate is not particularly limited. For example, a biuret bond, a urea bond, an isocyanurate bond, a uretdione bond, a urethane bond, and an allophanate may be added to the aliphatic diisocyanate and / or the alicyclic diisocyanate. Examples thereof include diisocyanate di- to 20-mer oligomers produced by forming bonds, oxadiazinetrione bonds, and the like. The polyisocyanate having a biuret bond is, for example, a so-called biuretizing agent such as water, t-butanol or urea and a diisocyanate at a molar ratio of the biuretizing agent to the isocyanate group of the diisocyanate of about 1/2 to about 1/100. After the reaction, it is obtained by removing and purifying unreacted diisocyanate. A polyisocyanate having an isocyanurate bond is obtained by, for example, carrying out a cyclic trimerization reaction with a catalyst or the like, stopping the reaction when the conversion rate is about 5 to about 80% by mass, and removing and purifying unreacted diisocyanate. . In this case, a 1-6 valent alcohol compound such as 1,3-butanediol or trimethylolpropane can be used in combination.

As the catalyst for producing the polyisocyanate having an isocyanurate bond, a catalyst having basicity is generally preferable. Examples of such catalysts include
(1) Tetraalkylammonium hydroxides such as tetramethylammonium, tetraethylammonium, tetrabutylammonium and trimethylbenzylammonium, and weak organic acid salts such as acetic acid and capric acid,
(2) Hydroxyalkylammonium hydroxides such as trimethylhydroxypropylammonium, trimethylhydroxyethylammonium, triethylhydroxypropylammonium and triethylhydroxyethylammonium, and weak organic acid salts such as acetic acid and capric acid,
(3) alkyl metal salts of alkyl carboxylic acids such as tin, zinc, lead and the like,
(4) Metal alcoholates such as sodium and potassium,
(5) Aminosilyl group-containing compound such as hexamethyldisilazane,
(6) Mannich bases,
(7) Combined use of tertiary amines and epoxy compounds,
(8) Phosphorus compounds such as tributylphosphine may be mentioned, and two or more of these may be used in combination.

  When the catalyst may adversely affect the properties of the paint or coating film, it is preferable to neutralize the catalyst with an acidic compound or the like. The acidic compound in this case is not particularly limited. For example, inorganic acids such as hydrochloric acid, phosphorous acid, phosphoric acid; methanesulfonic acid, p-toluenesulfonic acid, p-toluenesulfonic acid methyl ester, p-toluenesulfonic acid ethyl Sulfonic acids such as esters or derivatives thereof; ethyl phosphate, diethyl phosphate, isopropyl phosphate, diisopropyl phosphate, butyl phosphate, dibutyl phosphate, 2-ethylhexyl phosphate, di (2-ethylhexyl) phosphate, isodecyl phosphate, diisodecyl phosphate, oleyl acid phosphate, Examples include tetracosyl acid phosphate, ethyl glycol acid phosphate, butyl pyrophosphate, and butyl phosphite, and two or more of these may be used in combination.

  The polyisocyanate having a urethane bond is, for example, a di-isocyanate and a bivalent to hexavalent alcohol compound such as trimethylolpropane, and the molar ratio of the hydroxyl group of the alcohol compound to the isocyanate group of the diisocyanate is about 1/2 to about 1 /. After reacting at 100, unreacted diisocyanate can be removed and purified.

  The number average molecular weight of the polyisocyanate is not particularly limited, but is preferably 500 or more and 1500 or less, and more preferably 600 or more and 1300 or less. When the number average molecular weight is 500 or more, the flexibility of the coating film after baking tends to be secured favorably, and when the number average molecular weight is 1500 or less, the crosslinking density of the coating film after baking tends to be secured favorably. is there. In order to obtain a polyisocyanate having a number average molecular weight of 500 or more and 1500 or less, for example, the addition rate of the isocyanuration reaction may be set to 5.0 mass% to 80 mass%. The number average molecular weight can be measured by the method described in Examples described later.

  The viscosity of the polyisocyanate is not particularly limited, but is preferably 100 mPa · s or more and 100,000 mPa · s or less, more preferably 300 mPa · s or more and 50,000 mPa · s or less. When the viscosity is 100 mPa · s or more, there is a tendency to ensure good crosslinkability during baking, and when the viscosity is 100,000 mPa · s or less, the coating film smoothness after baking is maintained well. It tends to be possible. In order to obtain a polyisocyanate having a viscosity of 100 mPa · s or more and 100,000 mPa · s or less, a method of appropriately using a divalent to hexavalent alcohol compound at an appropriate conversion rate may be used. A viscosity can be measured by the method as described in the Example mentioned later.

  The isocyanate content of the polyisocyanate is not particularly limited, but is preferably 15% by mass or more and 25% by mass or less, more preferably 17% by mass or more and 24% by mass with respect to the total amount of solid content (100% by mass). It is as follows. When the isocyanate content is 15% by mass or more, the crosslinking density of the coating film after baking tends to be secured, and when the isocyanate content is 25% by mass or less, the flexibility of the coating film after baking is secured. Tend to be. In order to obtain a polyisocyanate having an isocyanate content of 15% by mass or more and 25% by mass or less with respect to the total amount (100% by mass) of the solid content, an appropriate 2 to 6-valent alcohol compound is appropriately converted. The method to use etc. are mentioned. The isocyanate content can be measured by the method described in Examples described later.

  The HDI monomer concentration of the polyisocyanate is not particularly limited, but is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, still more preferably 0.7% by mass or less, and even more. Preferably it is 0.5 mass% or less. When the HDI monomer concentration is 2.0% by mass or less, the danger during handling can be further reduced, and the curability of the coating composition can be further improved. In order to obtain a polyisocyanate having an HDI monomer concentration of 2.0% by mass or less, the polyisocyanate may be removed by evaporating a thin film, extracting, or the like after the polyisocyanate production. The HDI monomer concentration can be measured by the method described in Examples described later.

  The average number of isocyanate groups of the polyisocyanate formed from one or more selected from these polyisocyanates is preferably 2.0 or more and 20 or less. The lower limit of the average number of isocyanate groups is more preferably 2.3, still more preferably 2.5, and even more preferably 3.0. The upper limit of the average number of isocyanate groups is more preferably 15 and even more preferably 10. When the average number of isocyanate groups is 2.0 or more, the crosslinkability is improved, and when a blocked polyisocyanate is obtained, low temperature curability tends to be exhibited. On the other hand, when the average number of isocyanate groups is 20 or less, the viscosity is prevented from becoming too high, and a polyisocyanate having good workability tends to be obtained.

The average number of isocyanate groups is determined by the following formula. The number average molecular weight and isocyanate group mass% in the following formula are the above-described number average molecular weight and isocyanate content (mass%).

<Blocking agent>
In the block polyisocyanate composition of the present embodiment, the blocking agent contains a malonic acid diester compound. The malonic acid diester compound is preferably a compound represented by the following formula (II).

式（ＩＩ）中、Ｒ₃、及びＲ₄は、各々独立に、炭素数１〜８のアルキル基、フェニル基、又はベンジル基を示す。 In formula (II), R < ₃ > and R < ₄ > show a C1-C8 alkyl group, a phenyl group, or a benzyl group each independently. R ₃ and R ₄ may be the same or different, but are preferably the same from the standpoint of availability. By being a malonic acid diester compound in which R ₃ and R ₄ represent an alkyl group having 8 or less carbon atoms, a decrease in the effective NCO content is suppressed, and compatibility with the main agent when used as a paint is reduced. It tends to be able to be suppressed. Among these, it is more preferable that it is a malonic acid diester compound which shows a C1-C8 alkyl group, More preferably, it is a malonic acid diester compound which shows a C1-C4 alkyl group, More preferably, it is a methyl group. Or it is a malonic acid diester compound which shows an ethyl group, More preferably, it is a malonic acid diester compound which shows an ethyl group. Here, the effective NCO content is an isocyanate content (mass%) potentially present with respect to the total amount (100 mass%) of the block polyisocyanate composition.

In formula (II), R < ₃ > and R < ₄ > show a C1-C8 alkyl group, a phenyl group, or a benzyl group each independently.

  Specific examples of the malonic acid diester compound are not particularly limited, and examples thereof include, for example, dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, and diester malonate. Examples include t-butyl, methyl t-butyl malonate, di-n-hexyl malonate, di-2-ethylhexyl malonate, diphenyl malonate, and dibenzyl malonate. Among them, dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, di-t-butyl malonate, methyl t-butyl malonate, malonic acid Di n-hexyl and di-2-ethylhexyl malonate are preferred. More preferably, dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, di-t-butyl malonate, and methyl t-butyl malonate More preferably dimethyl malonate and diethyl malonate, and even more preferably diethyl malonate. The malonic acid diester shown above can be used alone or in combination of two or more.

  The blocking agent of this embodiment may further include a blocking agent other than the malonic acid diester compound (hereinafter also referred to as “other blocking agent”). The other blocking agent is not particularly limited, but is preferably a compound having one active hydrogen in the molecule. Although it does not specifically limit as a compound which has one active hydrogen in a molecule | numerator, For example, active methylene type | system | groups other than a malonic acid diester compound, mercaptan type | system | group, acid amide type | system | group, acid imide type | system | group, imidazole type | system | group, urea type | system | group, oxime type | system | group, Examples include amine-based, imide-based and pyrazole-based compounds.

As other specific blocking agents,
(1) Active methylenes other than malonic acid diester compounds; β-ketoester compounds such as methyl acetoacetate, ethyl acetoacetate, methyl isobutanoyl acetate, ethyl isobutanoyl acetate, acetylacetone, etc.
(2) Mercaptans: butyl mercaptan, dodecyl mercaptan, etc.
(3) Acid amide system: acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc.
(4) Acid imide type; succinimide, maleic imide, etc.
(5) Imidazole series; imidazole, 2-methylimidazole, etc.
(6) Urea system; urea, thiourea, ethylene urea, etc.
(7) Oxime type: formaldoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime (MEKO), cyclohexanone oxime, etc.
(8) Amine type; diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, diisobutylamine, di (2-butylamine), di (t-butyl) amine, dicyclohexylamine, Nt- Butylcyclohexylamine, 2-methylpiperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, etc.
(9) Imine type; ethyleneimine, polyethyleneimine, etc.
(10) Pyrazole type; pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like can be mentioned.

  Other preferable blocking agents are not particularly limited, but are at least one selected from active methylene-based and pyrazole-based blocking agents other than oxime-based, amine-based, acid amide-based, malonic acid diester compounds, and more preferably, At least one selected from active methylene-based and pyrazole-based blocking agents other than oxime-based and malonic acid diester compounds, and more preferably at least one selected from active methylene-based blocking agents other than malonic acid diester compounds A seed, and even more preferably an acetoacetate.

  In the blocking agent of this embodiment, the molar ratio of the malonic acid diester compound to the blocking agent other than the malonic acid diester compound is not particularly limited, but is preferably 1.0 or more. The lower limit of the molar ratio is preferably 1.0, more preferably 1.5, still more preferably 2.0, and even more preferably 3.0. Further, the upper limit of the molar ratio is more preferably 50, still more preferably 33, still more preferably 20, and still more preferably 10. When the lower limit value is 1.0 or more, the low temperature curability tends to be better, and when the upper limit value is 50 or less, the crystallinity at low temperatures can be further suppressed. It is in.

[Method for producing block polyisocyanate composition]
The manufacturing method of the block polyisocyanate composition of this embodiment is demonstrated. The production method of the block polyisocyanate composition of the present embodiment is roughly classified into, for example, two production methods (hereinafter referred to as “production method 1” and “production method 2”).

  First, production method 1 includes a polyisocyanate derived from at least one diisocyanate selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, a malonic acid diester compound represented by the following formula (II), and According to the method, a block polyisocyanate composition is produced by simultaneously forming a methanetetracarbonyl structure represented by the following formula (I) at the stage of producing a block polyisocyanate from a blocking agent other than the malonic acid diester compound. .

  On the other hand, the production method 2 includes a polyisocyanate derived from at least one diisocyanate selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate, a malonic acid diester compound, and if necessary, other than the malonic acid diester compound. A block polyisocyanate composition produced by mixing a block polyisocyanate containing a large amount of a methanetetracarbonyl structure represented by the following formula (I) separately from the block polyisocyanate produced from the block agent. is there.

式（Ｉ）中、Ｒ₁、及びＲ₂は、各々独立に、炭素数１〜８個のアルキル基、フェニル基、又はベンジル基を示す。）

式（ＩＩ）中、Ｒ₃、及びＲ₄は、各々独立に、炭素数１〜８のアルキル基、フェニル基、又はベンジル基を示す。

In formula (I), R _1, and R ₂ each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a benzyl group. )

In formula (II), R < ₃ > and R < ₄ > show a C1-C8 alkyl group, a phenyl group, or a benzyl group each independently.

<Manufacturing method 1>
From the viewpoint of ease of production, production method 1 is more preferable. Hereinafter, the production method 1 will be described in more detail.

  Production method 1 comprises a polyisocyanate derived from at least one diisocyanate selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate, a malonic acid diester compound, and if necessary, a blocking agent other than the malonic acid diester compound The first step of obtaining a blocked polyisocyanate and the subsequent second step of transesterifying the blocked polyisocyanate and monoalcohol are provided.

  The 1st process of the manufacturing method 1 is demonstrated. Furthermore, in the first step of production method 1, a case where a blocking agent other than the malonic acid diester compound is included as a blocking agent will be described. The molar ratio of the malonic acid diester compound to the blocking agent other than the malonic acid diester compound is not particularly limited, but the lower limit of the molar ratio is preferably 1.0, more preferably 1.5, Preferably it is 2.0, and even more preferably it is 3.0. The upper limit of the molar ratio is preferably 50, more preferably 33, still more preferably 20, and still more preferably 10. When the lower limit of the molar ratio is 1.0 or more, the low-temperature curability tends to be better, and when the upper limit of the molar ratio is 50 or less, the crystallinity at low temperatures It tends to be possible to suppress more.

The malonic acid diester compound in the 1st process of the manufacturing method 1 is a compound shown by the formula (II) mentioned above. In formula (II), R < ₃ > and R < ₄ > show a C1-C8 alkyl group, a phenyl group, or a benzyl group each independently. R ₃ and R ₄ may be the same or different, but R ₃ and R ₄ are preferably the same for ease of availability. When R ₃ and R ₄ are each independently an alkyl group having 8 or less carbon atoms, the decrease in the effective NCO content is suppressed, and the deterioration in compatibility with the main agent and the like when used as a paint is suppressed. Tend to be able to. Among these, it is preferable that R < ₃ > and R < ₄ > are respectively independently a C1-C8 alkyl group, More preferably, it is a C1-C4 alkyl group, More preferably, a methyl group and An ethyl group, and more preferably an ethyl group. Here, the effective NCO content is the content (mass%) of isocyanate groups potentially present with respect to the total quantity (100 mass%) of the block polyisocyanate composition.

  Specific examples of the malonic acid diester are not particularly limited. For example, dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, di-t malonate -Butyl, methyl t-butyl malonate, di-n-hexyl malonate, di-2-ethylhexyl malonate, diphenyl malonate, and dibenzyl malonate. Among them, dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, di-t-butyl malonate, methyl t-butyl malonate, malonic acid Di n-hexyl and di-2-ethylhexyl malonate are preferred, more preferably dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, malon Di-t-butyl acid and methyl malonate t-butyl ester, more preferably dimethyl malonate and diethyl malonate, and even more preferably diethyl malonate. The malonic acid diester shown above can be used alone or in combination of two or more.

  The blocking agent other than the malonic acid diester compound in the first step of production method 1 (hereinafter also referred to as “other block”) is not particularly limited, but is preferably a compound having one active hydrogen in the molecule. . Although it does not specifically limit as a compound which has one active hydrogen in a molecule | numerator, For example, active methylene type | system | groups other than a malonic acid diester compound, mercaptan type | system | group, acid amide type | system | group, acid imide type | system | group, imidazole type | system | group, urea type | system | group, oxime type | system | group, Examples include amine-based, imide-based and pyrazole-based compounds.

As other specific blocking agents,
(1) Active methylenes other than malonic acid diester compounds; β-ketoester compounds such as methyl acetoacetate, ethyl acetoacetate, methyl isobutanoyl acetate, ethyl isobutanoyl acetate, acetylacetone, etc.
(2) Mercaptans: butyl mercaptan, dodecyl mercaptan, etc.
(3) Acid amide system: acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc.
(4) Acid imide type; succinimide, maleic imide, etc.
(5) Imidazole series; imidazole, 2-methylimidazole, etc.
(6) Urea system; urea, thiourea, ethylene urea, etc.
(7) Oxime series: formaldoxime, acetaldoxime, acetoxime, methylethylketoxime, cyclohexanone oxime, etc.
(8) Amine type; diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine, diisobutylamine, di (2-butylamine), di (t-butyl) amine, dicyclohexylamine, Nt- Butylcyclohexylamine, 2-methylpiperidine, 2,6-dimethylpiperidine, 2,2,6,6-tetramethylpiperidine, etc.
(9) Imine type; ethyleneimine, polyethyleneimine, etc.
(10) Pyrazole type; pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like can be mentioned.

Preferable other blocking agents are not particularly limited, but are at least one selected from active methylene-based and pyrazole-based blocking agents other than oxime-based, amine-based, acid amide-based, and malonic acid diester compounds, and more preferably , At least one selected from active methylene-based and pyrazole-based blocking agents other than oxime-based and malonic acid diester compounds, and more preferably at least selected from active methylene-based blocking agents other than malonic acid diester compounds 1 type, and even more preferably an acetoacetate.
In the first step of production method 1, the malonic acid diester compound and the blocking agent other than the malonic acid diester compound may be reacted with the polyisocyanate at the same time. After reacting, the other blocking agent may be reacted.

  In the present embodiment, the blocking reaction (reaction between polyisocyanate and blocking agent) is preferably performed so as to block all isocyanate groups of the polyisocyanate. From this viewpoint, the molar ratio of the blocking agent to the isocyanate group in the polyisocyanate ((total number of moles of blocking agent) / (number of moles of isocyanate group in the polyisocyanate)) is 1.0 or more and 1.5 or less. preferable. The lower limit of the molar ratio is more preferably 1.015, still more preferably 1.030, and still more preferably 1.045. The upper limit of the molar ratio is more preferably 1.35, further preferably 1.20, and still more preferably 1.10. By setting the lower limit of the molar ratio to 1.0, the low-temperature curability of the block polyisocyanate tends to be expressed more, and by setting the upper limit of the molar ratio to 1.5 or less, coating There exists a tendency which can suppress the fall of subsequent drying property.

  The reaction in the first step can be performed regardless of the presence or absence of a solvent. When using a solvent, it is preferable to use a solvent which is inert with respect to the isocyanate group. Although it does not specifically limit as the solvent, For example, aromatic hydrocarbons, such as toluene and xylene; Ketones, such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Esters, such as ethyl acetate, acetic acid-n-butyl, and cellosolve acetate; From the group of ether solvents such as propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether, a solvent can be appropriately selected and used according to the purpose and application. These solvents may be used alone or in combination of two or more.

  In the blocking reaction in the first step, a reaction catalyst can be used. Although it does not specifically limit as a specific reaction catalyst, For example, organometallic salt, such as tin, zinc, lead, metal alcoholate, and tertiary amine are mentioned.

  In order to ensure the production amount of the methanetetracarbonyl structure of this embodiment, it is preferable that the reaction catalyst is continuously added over time. The time for dropping is preferably from 2.0 minutes to 120 minutes. The lower limit of the time is more preferably 3.0 minutes, further preferably 5.0 minutes, and still more preferably 7.0 minutes. The upper limit of the time is more preferably 90 minutes, still more preferably 60 minutes, and even more preferably 30 minutes. By setting the lower limit of the time to 2.0 minutes or more, it tends to be easy to adjust to the range of the present embodiment by increasing the amount of methane tetracarbonyl structure generated, and the upper limit of the time By setting the value to 120 minutes or less, the amount of methane tetracarbonyl structure produced does not become too large, and can easily be adjusted within the range of the present embodiment, and further, the reaction time can be prevented from extending.

  When the reaction catalyst used may adversely affect the properties of the paint or coating film, it is preferable to deactivate the reaction catalyst with an acidic compound or the like. The acidic compound in this case is not particularly limited. For example, inorganic acids such as hydrochloric acid, phosphorous acid, phosphoric acid; methanesulfonic acid, p-toluenesulfonic acid, p-toluenesulfonic acid methyl ester, p-toluenesulfonic acid ethyl Sulfonic acids such as esters or derivatives thereof; monoethyl phosphate, diethyl phosphate, monoisopropyl phosphate, diisopropyl phosphate, monobutyl phosphate, dibutyl phosphate, mono (2-ethylhexyl) phosphate, di (2-ethylhexyl) phosphate, monoisodecyl phosphate, diisodecyl phosphate, Examples include oleyl acid phosphate, tetracosyl acid phosphate, ethyl glycol acid phosphate, butyl pyrophosphate, and butyl phosphite. Two or more of these acidic compounds may be used in combination.

  The reaction temperature in the first step is generally preferably −20 ° C. or higher and 150 ° C. or lower, more preferably 0 ° C. or higher and 100 ° C. or lower, and further preferably 40 ° C. or higher and 80 ° C. or lower. By performing the reaction at a reaction temperature of 150 ° C. or lower, side reactions tend to be suppressed, and by performing the reaction at a reaction temperature of −20 ° C. or higher, the reaction rate tends to be maintained high.

  Next, the 2nd process of the manufacturing method 1 is demonstrated. The second step is a step of reacting the block polyisocyanate obtained in the first step with a monohydric alcohol compound.

  The block polyisocyanate composition of the present embodiment includes a block polyisocyanate composition of the present embodiment in order to improve storage stability when blended with at least one selected from the group consisting of polyols, polyamines and alkanolamines. As the step of mixing and reacting with the monohydric alcohol compound, the second step is preferably performed.

  The mixing temperature in the second step is preferably -20 ° C or higher and 150 ° C or lower, more preferably 0 ° C or higher and 100 ° C or lower, and further preferably 40 ° C or higher and 80 ° C or lower. Side reaction tends to be suppressed by carrying out the reaction at a mixing temperature of 150 ° C. or lower, and the mixing time tends to be shortened by carrying out the reaction at a mixing temperature of −20 ° C. or higher. .

<Manufacturing method 2>
In the production method 2, for example, the block polyisocyanate obtained by the same steps as the first step and the second step of the production method 1 is separately produced as a third step having a high methanetetracarbonyl structure content ratio. The block polyisocyanate thus obtained is mixed to adjust the methanetetracarbonyl structure content ratio of the entire block polyisocyanate composition obtained.

  A block polyisocyanate having a high methanetetracarbonyl structure content ratio obtained separately is prepared by adjusting the molar ratio of the malonic acid diester compound to 0.5 or less and 0.9 or less of the isocyanate group of the polyisocyanate. It can manufacture by performing the process similar to 1 process. The lower limit of the molar ratio is more preferably 0.55, still more preferably 0.60, and still more preferably 0.65. The upper limit of the molar ratio is more preferably 0.85, further preferably 0.80, and still more preferably 0.75. By setting the lower limit of the molar ratio to 0.5 or more, gelation during the reaction tends to be suppressed. By setting the upper limit of the molar ratio to 1.0 or less, methanetetracarbonyl There is a tendency that the generation amount of the structure can be increased.

  Further, it is preferable that the block polyisocyanate having a high methanetetracarbonyl structure ratio is mixed and reacted with a monohydric alcohol compound as the second step of the production method 1 after the reaction of the polyisocyanate and the malonic acid diester compound. .

  The average number of isocyanate groups of the polyisocyanate used for the block polyisocyanate having a high methanetetracarbonyl structure content ratio is preferably 1.0 or more and 4.0 or less. The lower limit of the average number of isocyanate groups is more preferably 1.5, still more preferably 1.7, and even more preferably 1.9. The upper limit of the average number of isocyanate groups is more preferably 3.0, still more preferably 2.5, and even more preferably 2.0. When the lower limit value of the average number of isocyanate groups is 1.0 or more, the production ratio of the methanetetracarbonyl structure tends to be increased, and the upper limit value of the average number of isocyanate groups is 4.0 or less. There is a tendency that gelation during the production of the methanetetracarbonyl structure can be suppressed.

  Moreover, the thing similar to the compound described in the said manufacturing process 1 can be used for the malonic acid diester compound and monohydric alcohol compound used at the time of block polyisocyanate production with a high methanetetracarbonyl structure content rate.

  The mixing temperature in the third step is preferably -20 ° C or higher and 150 ° C or lower, more preferably 0 ° C or higher and 100 ° C or lower, more preferably 40 ° C or higher and 80 ° C or lower. The side reaction tends to be suppressed by mixing at a mixing temperature of 150 ° C. or lower, and the mixing time tends to be shortened by mixing at −20 ° C. or higher.

[One-pack type coating composition]
The one-component coating composition of the present embodiment includes the block polyisocyanate composition of the present embodiment and at least one of a polyol, a polyamine, and an alkanolamine. Moreover, it is preferable that a one-pack type coating composition contains a polyol at least. In order to improve the storage stability of the one-component coating composition, it is preferable that the block polyisocyanate composition of the present embodiment further contains the above-described monohydric alcohol compound.

  The block polyisocyanate composition is preferably a main component of the one-part coating composition together with at least one of polyol, polyamine and alkanolamine.

  Specific examples of the polyol are not particularly limited, and examples thereof include polyester polyol, acrylic polyol, polyether polyol, polyolefin polyol, fluorine polyol, polycarbonate polyol, and polyurethane polyol.

  Polyester polyol is not particularly limited, but for example, a dibasic acid selected from the group of succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid carboxylic acid alone Or a polyester polyol obtained by a condensation reaction of a mixture and a polyhydric alcohol selected from the group of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, and glycerin alone or in a mixture, and a polyhydric alcohol. Examples thereof include polycaprolactones obtained by ring-opening polymerization of ε-caprolactone used.

  The acrylic polyol is not particularly limited, but for example, an ethylenically unsaturated bond-containing monomer having a hydroxyl group alone or a mixture thereof, and another ethylenically unsaturated bond-containing monomer copolymerizable therewith or It is obtained by copolymerizing with a mixture.

  The polyether polyols are not particularly limited, but for example, using a polybasic hydroxy compound alone or in a mixture, a hydroxide such as lithium, sodium or potassium, an alcoholate, or a strongly basic catalyst such as an alkylamine, Polyether polyols obtained by adding a single or mixture of alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, styrene oxide or the like; polyalkylene compounds obtained by reacting alkylene oxide with a polyfunctional compound such as ethylenediamine Ether polyols; so-called polymer polyols obtained by polymerizing acrylamide or the like using these polyether polyols as media.

  The polyolefin polyol is not particularly limited, and examples thereof include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene. The number of hydroxyl groups (average number of hydroxyl groups) possessed by one statistical molecule of polyol is preferably 2.0 or more. It exists in the tendency which can suppress the fall of the crosslinking density of the obtained coating film because the hydroxyl group average number of a polyol is 2.0 or more.

  The fluorine polyol is a polyol containing fluorine in the molecule and is not particularly limited. For example, fluoroolefins, cyclovinyl ethers, hydroxyalkyls disclosed in JP-A-57-34107 and JP-A-61-275111. Examples thereof include copolymers such as vinyl ether and vinyl monocarboxylic acid.

  Polycarbonate polyols are not particularly limited. For example, low molecular carbonate compounds such as dialkyl carbonates such as dimethyl carbonate, alkylene carbonates such as ethylene carbonate, diaryl carbonates such as diphenyl carbonate, and the low molecular weight compounds used in the above-described polyester polyols. Examples thereof include those obtained by condensation polymerization of polyols.

  Although a polyurethane polyol is not specifically limited, For example, it can be obtained by making a polyol and polyisocyanate react.

  The hydroxyl value per resin of the polyol is preferably 10 mgKOH / resin g or more and 300 mgKOH / resin g or less. When the hydroxyl value per resin is 10 mgKOH / resin g or more, the crosslinking density is suppressed from decreasing, and the target physical properties of this embodiment tend to be sufficiently achieved. On the other hand, when the hydroxyl value per resin is 300 mgKOH / resin g or less, the crosslinking density is prevented from excessively increasing, and the mechanical properties of the coating film tend to be maintained at a high level.

  The acid value per resin of the polyol is preferably 5.0 mg KOH / resin g or more and 150 mg KOH / resin g or less, more preferably 8.0 mg KOH / resin g or more and 120 mg KOH / resin g or less, and further preferably 10 mg KOH / resin or less. The resin g is 100 mgKOH / resin g or less. When the acid value is 5.0 mgKOH / resin g or more, the water dispersibility tends to be kept high, and when it is 150 mgKOH / resin g or less, the decrease in water resistance of the coating film is suppressed. It tends to be possible.

  Among the polyols listed above, acrylic polyol and polyester polyol are more preferable. In the coating composition in the case of using a polyol, the equivalent ratio of the blocked isocyanate group to the hydroxyl group of the polyol is preferably set to 10: 1 to 1:10.

  As the polyamine, those having two or more primary amino groups or secondary amino groups in one molecule are preferably used, and those having three or more in one molecule are more preferable.

  Moreover, alkanolamine here means the compound which has an amino group and a hydroxyl group in 1 molecule. The alkanolamine is not particularly limited, and examples thereof include monoethanolamine, diethanolamine, aminoethylethanolamine, N- (2-hydroxypropyl) ethylenediamine, mono-, di- (n- or iso-) propanolamine, and ethylene glycol. -Bis-propylamine, neopentanolamine, and methylethanolamine.

  A known melamine resin, epoxy resin, or polyurethane resin can be contained in the one-pack type coating composition of the present embodiment. Moreover, when the polyol mentioned above has a carboxyl group, an oxazoline group containing compound and a carbodiimide group containing compound can be contained. Moreover, when the polyol mentioned above has a carbonyl group, a hydrazide group containing compound and a semicarbazide group containing compound can be contained. These compounds can be blended not only alone but also two or more compounds.

  The one-component coating composition of the present embodiment is optionally provided with, for example, hindered phenol as an antioxidant, benzotriazole, benzophenone, etc. as an ultraviolet absorber, and as a pigment, for example, titanium oxide, carbon black, indigo, Quinacridone, pearl mica, etc., metal powder pigments such as aluminum, etc., rheology control agents such as hydroxyethyl cellulose, urea compounds, microgels, etc., and curing accelerators such as tin compounds, zinc compounds, amine compounds, etc. may be included.

[Coated article]
The coated article of this embodiment is coated with the one-component coating composition of this embodiment. For example, with the one-part coating composition of the present embodiment, by roll coating, curtain flow coating, spray coating, electrostatic coating, bell coating, etc., it can be made into materials such as steel, surface-treated steel plates and other metals and plastics, inorganic materials, etc. , Primer, intermediate coating, or top coating is suitably applied to obtain a coated article. This one-pack type coating composition further imparts cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, adhesion, etc. to pre-coated metal, automobile coating, plastic coating, etc. including rust-proof steel sheets. Is preferably used. The one-pack type coating composition is also useful as a urethane raw material for adhesives, pressure-sensitive adhesives, elastomers, foams, surface treatment agents and the like.

[Coating]
The coating film of this embodiment is formed by the one-component coating composition of this embodiment. That is, the one-component coating composition of the present embodiment forms a coating film of the present embodiment through a baking process after coating by roll coating, curtain flow coating, spray coating, electrostatic coating, bell coating, etc. Can do. The one-pack type coating composition (coating composition) used for forming this coating film is preferably subjected to a baking step to form a crosslinked coating film. The crosslinked coating film after curing of the one-pack type coating composition has polar groups such as amide bonds and ester bonds derived from blocked isocyanate groups, as well as urethane bonds derived from polyisocyanates before blocking reaction. Therefore, the cross-linked coating film formed from the one-pack type coating composition of the present embodiment is subjected to layer coating or recoating in addition to chemical resistance, heat resistance, water resistance, etc., which are characteristics of general urethane cross-linked coating films. When performed, hydrogen bonding between layers becomes possible, and the adhesion between layers is excellent. Even in the coating film in which the crosslinked structure is not completely formed after the baking step, the coating film has the above polar group, so that it is excellent in adhesion as well as the crosslinked coating film at the time of lamination coating or recoating.

  In addition, when several layers of coating liquid are laminated by wet-on-wet as in the coating of a new car line of an automobile, an organic amine compound is present in the coating composition of this embodiment or in the crosslinked coating film after curing. There is also the possibility of acting as a catalyst for the crosslinking reaction of the lower layer or the upper layer.

  Hereinafter, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to these examples. First, measurement and evaluation methods for various physical properties will be described.

(Physical property 1) Number average molecular weight The number average molecular weight of polyisocyanate was calculated | required by the number average molecular weight of the polystyrene reference | standard by the gel permeation chromatograph (henceforth "GPC") measurement using the following apparatus.
Equipment: “HLC-8120GPC” (trade name) manufactured by Tosoh Corporation
Column: "TSKgel SuperH1000" (product name) x 1 manufactured by Tosoh Corporation
"TSKgel SuperH2000" (trade name) x 1
"TSKgel SuperH3000" (trade name) x 1 Carrier: Tetrahydrofuran Detection method: Differential refractometer

Moreover, the number average molecular weight of the polyol was calculated | required by the number average molecular weight of the polystyrene reference | standard by the following GPC measurement.
Equipment: “HLC-8120GPC” (trade name) manufactured by Tosoh Corporation
Column: “TSKgel SuperHM-H” (trade name) x 2 manufactured by Tosoh Corporation Carrier: N, N-dimethylformamide Detection method: differential refractometer

(Physical property 2) Viscosity (mPa · s)
The viscosity of the polyisocyanate was measured at 25 ° C. using an E-type viscometer (manufactured by Tokimec). In the measurement, a standard rotor (1 ° 34 ′ × R24) was used. The number of rotations was as follows.
100 rpm (when less than 128 mPa · s)
50 rpm (128 mPa · s or more and less than 256 mPa · s)
20 rpm (256 mPa · s or more and less than 640 mPa · s)
10 rpm (in the case of 640 mPa · s or more and less than 1280 mPa · s)
5 rpm (in the case of 1280 mPa · s or more and less than 2560 mPa · s)

(Physical property 3) NCO content (mass%)
The NCO content (isocyanate content, mass%) of the polyisocyanate was determined by back titration with 1N hydrochloric acid after neutralizing the isocyanate group in the measurement sample with an excess of 2N amine. In addition, the non-volatile content of the polyisocyanate composition produced by the Example and comparative example which are mentioned later was investigated by the method mentioned above, and the thing whose value was 98 mass% or more was measured as it was.

(Physical property 4) HDI monomer concentration (% by mass)
The HDI monomer concentration of the polyisocyanate was determined as follows. First, a 20 mL sample bottle was placed on a digital balance, and about 1 g of the sample was precisely weighed. Next, 0.03 to 0.04 g of nitrobenzene (internal standard solution) was added and precisely weighed. Finally, after adding about 9 mL of ethyl acetate, the lid was tightly mixed well to prepare the sample. The adjustment liquid was quantitatively analyzed by gas chromatography under the following conditions.
Equipment: “GC-8A” (trade name) manufactured by SHIMADZU
Column: “Silicon OV-17” (trade name) manufactured by Shinwa Kako Co., Ltd.
Column oven temperature: 120 ° C
Injection / detector temperature: 160 ° C

(Physical property 5) Average number of isocyanate groups The average number of isocyanate groups of the polyisocyanate was calculated by the following general formula from the number average molecular weight of (Physical property 1) and the NCO content (isocyanate concentration) of (Physical property 3).

(Physical property 6) Solid content concentration (mass%)
After precisely weighing an aluminum dish having a bottom diameter of 38 mm, the block polyisocyanate composition of Example or Comparative Example was precisely weighed with about 1 g on the aluminum dish (W1), and the block polyisocyanate composition was made to a uniform thickness. After adjustment, it was kept in an oven at 105 ° C. for 1 hour. After the aluminum dish reached room temperature, the block polyisocyanate composition remaining on the aluminum dish was precisely weighed (W2).
Solid concentration = W2 / W1 × 100

(Physical property 7) Effective NCO content (mass%)
The effective NCO content of the block polyisocyanate was determined as follows. Here, the effective NCO content (% by mass) is to quantify the amount of blocked isocyanate groups that can participate in the crosslinking reaction present in the blocked polyisocyanate composition after the blocking reaction. Expressed as mass%, it was calculated by the following formula.
{(Solid content (mass%) of block polyisocyanate composition) × (mass of polyisocyanate used in reaction × isocyanate group content% of precursor polyisocyanate)} / (block polyisocyanate composition after blocking reaction) Resin mass)
In addition, when the sample was diluted with a solvent etc., the value in the diluted state was described.

(Physical property 8) Methanetetracarbonyl structure ratio (mol%)
The methanetetracarbonyl structure ratio of the block polyisocyanate composition was determined as follows. By measurement of ¹ H-NMR using “Avance 600” (trade name) manufactured by Bruker Biospin, methane tetracarbonyl structure / (methane tetracarbonyl structure + keto form of methane tricarbonyl structure + enol form of methane tricarbonyl structure) The molar ratio was determined. Specific measurement conditions were as follows.
Apparatus: “Avance600” (trade name) manufactured by BrukerBiospin
Solvent: Deuterated chloroform Accumulated number: 256 Sample concentration: 5.0% by mass
Chemical shift standard: Tetramethylsilane was 0 ppm.

・メタントリカルボニル構造（下記式（ＩＶ）で示される構造）のエノール体ＮＨプロトン：９．８ｐｐｍ付近：積分値÷１

・メタンテトラカルボニル構造（下記式（Ｉ）で示される構造）のＮＨプロトン：８．０ｐｐｍ付近：積分値÷２

The integral values of the following signals were divided by the number of carbons being measured, and each molar ratio was determined from the value.
-Keto NH proton of methanetricarbonyl structure (structure represented by the following formula (III)): around 7.3 ppm: integral value / 1

Enol NH proton of methanetricarbonyl structure (structure represented by the following formula (IV)): around 9.8 ppm: integral value / 1

-NH proton of methanetetracarbonyl structure (structure represented by the following formula (I)): around 8.0 ppm: integral value / 2

(Evaluation 1) Low-temperature curability “Setalux 1152” (acrylic polyol, trade name manufactured by Nuplex Resins, hydroxyl value 138 mg KOH / resin g, solid content concentration 51 mass%) and block polyisocyanate composition, NCO / OH = 1 0 and blended with butyl acetate for Ford Cup No. 4 was adjusted to 20 seconds / 23 ° C. to obtain an α coating solution.

  The obtained α coating solution was applied to a PP plate with an air spray gun to a dry film thickness of 40 μm, dried at a temperature of 23 ° C. for 30 minutes, and baked at 90 ° C. for 20 minutes to obtain a cured coating film. .

The obtained cured coating film was baked, left at 20 ° C. for 1 hour, peeled off from the PP plate, immersed in acetone at 20 ° C. for 24 hours, and the value (gel fraction) of the undissolved part mass relative to the mass before immersion. Calculated and evaluated according to the following criteria.
◎: Gel fraction is 90% or more ○: Gel fraction is 80% or more and less than 90% △: Gel fraction is 70% or more and less than 80% ×: Gel fraction is less than 70%

(Evaluation 2) Adhesiveness with upper coating film The α coating solution obtained in the above (Evaluation 1) was applied to a mild steel plate with an air spray gun so that the dry film thickness was 40 μm, and the temperature was 23 ° C. After drying for 20 minutes, baking was performed at 90 ° C. for 20 minutes to obtain an α coating layer 1. The adhesion test with the mild steel sheet of the α coating layer 1 was performed according to JIS K5600-5-6. As a result, no peeling was observed, including some floats.

  “Setalux 1767” (acrylic polyol, trade name of Nuplex Resins, hydroxyl value 150 mg KOH / resin g, solid content 65 mass%) 70 parts, hexamethoxymethylated melamine resin “Cymel (registered trademark) 300” manufactured by Nippon Cytec Co., Ltd. After mixing 30 parts by mass and 1 part by mass of p-toluenesulfonic acid, the Ford Cup No. 4 was adjusted to 20 seconds / 23 ° C. to obtain a β coating solution.

Separately, the α coating solution obtained in the above (Evaluation 1) was applied to a mild steel plate with an air spray gun to a dry film thickness of 40 μm, dried at a temperature of 23 ° C. for 30 minutes, and then at 90 ° C. for 20 minutes. Baking was performed to obtain an α coating layer 2. The α coating layer 2 is coated with a β coating solution so as to have a dry film thickness of 40 μm, dried at a temperature of 23 ° C. for 30 minutes, and then baked at 14 ° C. for 30 minutes to form a multilayer coating having an α layer and a β layer. A membrane was obtained. The adhesion test of the multilayer coating film having the α layer and the β layer was conducted according to JIS K5600-5-6. Evaluation was made according to the following criteria.
◎: Peeling paint film, no lift ○: Partly lifted at the cut part △: Less than half peeled film ×: Half or more peeled film

(Evaluation 3) Compatibility The α coating solution obtained in the above (Evaluation 1) was applied to a glass plate with an air spray gun so as to have a dry film thickness of 80 μm. The film was dried at a temperature of 23 ° C. for 30 minutes, baked at 90 ° C. for 20 minutes, and then cooled. It observed visually and evaluated on the following reference | standard.
○: Transparent △: Slightly cloudy ×: Strongly cloudy

<Production Example 1> Polyisocyanate P-1
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen blowing tube, and dropping funnel is placed in a nitrogen atmosphere, charged with 1100 parts by mass of HDI and 1.2 parts by mass of 1,3-butanediol, and reacted with stirring. The internal temperature was maintained at 80 ° C. for 2 hours. Thereafter, the temperature in the reactor was kept at 60 ° C., tetrabutylammonium acetate was added, and phosphoric acid was added when the NCO content of the reaction solution reached 41.3 mass% to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin film evaporator, the viscosity at 25 ° C. was 3800 mPas, the isocyanate content was 21.0%, the HDI monomer concentration was 0.2% by mass, and the average number of isocyanate groups was 3. .6 polyisocyanate P-1 was obtained.

<Production Example 2> Polyisocyanate P-2
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen blowing tube is placed in a nitrogen atmosphere, charged with 100 parts by mass of HDI and 3.3 parts by mass of trimethylolpropane. Hold for 2 hours at ° C. Thereafter, the temperature in the reactor was maintained at 60 ° C., tetrabutylammonium acetate was added, and phosphoric acid was added to stop the reaction when the NCO content of the reaction solution reached 36.3% by mass. After the reaction solution was filtered, unreacted HDI was removed using a thin film evaporator. Polyisocyanate P-2 having a viscosity at 25 ° C. of 25000 mPas, an isocyanate content of 19.5%, an HDI monomer concentration of 0.2% by mass, and an average number of isocyanate groups of 5.1 was obtained.

<Production Example 3> Polyisocyanate P-3
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen blowing tube is placed in a nitrogen atmosphere, charged with 100 parts of HDI, maintained in the reactor at 60 ° C. with stirring, and added tetrabutylammonium acetate. When the NCO content of the reaction solution reached 43.8% by mass, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin film evaporator, the viscosity at 25 ° C. was 1700 mPas, the isocyanate content was 23.0%, the HDI monomer concentration was 0.2 mass%, and the average number of isocyanate groups was 3. 2. An isocyanurate type polyisocyanate P-3 was obtained.

<Production Example 4> Block polyisocyanate M-1 having a high methanetetracarbonyl structure ratio
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen blowing tube is placed in a nitrogen atmosphere, and 100 parts by mass of hexamethylene diisocyanate monomer and 131 parts by mass of diethyl malonate ((molar ratio of diethyl malonate) / (Molar ratio of isocyanate group) = 0.77 times), 82 parts by mass of butyl acetate were added, 0.7 part by mass of 28% sodium methylate solution was added at room temperature, and the reaction was performed at 60 ° C. for 6 hours. Sampling was performed at this point, and ¹ H-NMR was conducted. As a result, the methanetetracarbonyl structure: 50 mol%, the methanetricarbonyl structure: 45 mol%, and the diethyl malonate: 5 mol% were obtained. In addition, the quantification of diethyl malonate was calculated from the peak detected at 3.4 ppm / 2 by ¹ H-NMR measurement. Thereafter, 60 parts by mass of 1-butanol was added, and stirring was continued at that temperature for 1 hour. Thereto was added 0.7 part by mass of 2-ethylhexyl acid phosphate, and the mixture was stirred for 30 minutes and then cooled. When ¹ H-NMR was performed again, the methane tetracarbonyl structure: 26 mol%, the methanetricarbonyl structure: 69 mol%, diethyl malonate: 60% resin content containing 5 mol%, the effective NCO content: 6. 4 mass%, block polyisocyanate M-1 containing a methanetetracarbonyl structure was obtained.

<Example 1>
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen blowing tube is placed in a nitrogen atmosphere, 100 parts by mass of polyisocyanate P-1, 67 parts by mass of diethyl malonate, 14 parts by mass of ethyl acetoacetate, 39 parts by mass of n-butyl acetate was charged, 0.8 part by mass of a 28% sodium methylate solution was added at a rate of 0.16 parts by mass / minute at room temperature, and reacted at 60 ° C. for 6 hours. Thereafter, 74 parts by mass of 1-butanol was added and stirring was continued at that temperature for 2 hours. Thereto was added 0.8 part by mass of mono (2-ethylhexyl) phosphate to obtain a block polyisocyanate composition B-1 having a resin content of 60% by mass and an effective NCO content of 7.1% by mass. ¹ H-NMR measurement of the obtained block polyisocyanate composition B-1 was carried out, and the methanetetracarbonyl structure ratio in the isocyanate-malonic acid diester bond structure was quantified. Moreover, the above-described evaluations (Evaluation 1) to (Evaluation 3) were performed. The obtained results are shown in Table 1.

<Examples 2-4, 6-7, Comparative Examples 1-2>
In Examples 2 to 4, 6 to 7 and Comparative Examples 1 and 2, the block polyisocyanate compositions B-2 to B-4 and B6 to B were used in the same manner as in Example 1 except that the formulations shown in Table 1 were used. B9 was obtained. Tables 1 and 2 show physical property values and evaluation results of the obtained block polyisocyanate composition. In Tables 1 and 2, methyl ethyl ketoxime is indicated as “MEKO”.

<Example 5>
A four-necked flask equipped with a stirrer, thermometer, reflux condenser, and nitrogen blowing tube is placed in a nitrogen atmosphere, 100 parts by mass of polyisocyanate P-1, 67 parts by mass of diethyl malonate, 14 parts by mass of ethyl acetoacetate, 39 parts by mass of n-butyl acetate was charged, 0.8 part by mass of a 28% sodium methylate solution was added at a rate of 0.8 part by mass / minute at room temperature, and the reaction was carried out at 60 ° C. for 6 hours. Thereafter, 74 parts by mass of 1-butanol was added, and stirring was continued at that temperature for 2 hours. Thereto was added 0.8 part by mass of mono (2-ethylhexyl) phosphate. Thereafter, 50 parts by mass of block polyisocyanate M-1 containing methanetetracarbonyl structure was added, and block poly having a resin content of 60% by mass, an effective NCO content of 7.0% by mass, and an isocyanate-malonic acid diester bond structure ratio of 83% by mol. Isocyanate composition B-5 was obtained. ¹ H-NMR measurement of the obtained B-5 was performed, and the methanetetracarbonyl structure ratio in the isocyanate-malonic acid diester bond structure was quantified. Moreover, the above-described evaluations (Evaluation 1) to (Evaluation 3) were performed. The obtained results are shown in Table 1.

<Comparative Example 3>
A block polyisocyanate composition B-10 was obtained in the same manner as in Example 5 except that the composition shown in Table 1 was used. Table 2 shows the physical properties and evaluation results of the obtained block polyisocyanate composition B-10.

  From the results of the above examples and comparative examples, the block polyisocyanate composition of the present embodiment has a low-temperature curability that can be cross-linked at a baking temperature of 100 ° C. or lower, while maintaining adhesion to the upper coating film. It was found to be excellent and compatible with polyol.

  The block polyisocyanate composition according to the present invention can be suitably used as a one-pack type coating composition excellent in low-temperature curability, adhesion to the upper layer, and compatibility with polyol.

Claims (8)

A block polyisocyanate obtained from a polyisocyanate derived from at least one diisocyanate selected from the group consisting of an aliphatic diisocyanate and an alicyclic diisocyanate, and a blocking agent,
The blocking agent includes a malonic acid diester compound,
The malonic acid diester compound includes diethyl malonate,
The block polyisocyanate composition whose ratio of the methane tetracarbonyl structure shown by following formula (I) with respect to the total amount of an isocyanate-malonic acid diester bond structure is 0.5 mol% or more and 10 mol% or less.

(In formula (I), R ₁ and R ₂ each independently represents an alkyl group having 1 to 8 carbon atoms, a phenyl group, or a benzyl group.)   The blocked polyisocyanate composition according to claim 1, wherein the blocking agent further comprises a blocking agent other than the malonic acid diester compound.   The block polyisocyanate composition according to claim 2, wherein in the blocking agent, a molar ratio of the malonic acid diester compound to a blocking agent other than the malonic acid diester compound is 1.0 or more.   The block polyisocyanate composition according to claim 2 or 3, wherein the blocking agent other than the malonic acid diester compound contains ethyl acetoacetate. Further comprising a monohydric alcohol compound,
The block polyisocyanate composition according to any one of claims 1 to 4 , wherein a molar ratio of the monohydric alcohol compound to a block polyisocyanate group of the block polyisocyanate composition is 0.2 or more and 10 or less. The one-pack type coating composition containing the block polyisocyanate composition as described in any one of Claims 1-5 , and a polyol. A coating film formed from the one-component coating composition according to claim 6 . A coated article coated with the one-component coating composition according to claim 6 .