JP2023101150A - Blocked polyisocyanate composition, resin composition, resin film and laminate - Google Patents

Abstract

To provide a blocked polyisocyanate composition that gives an aqueous resin composition having high dispersibility, and also improves the pot life of a coating, has good curability when baked at a low temperature of 90°C or less, and also gives a coating layer having high water resistance.SOLUTION: A blocked polyisocyanate composition contains a blocked polyisocyanate which is derived from a polyisocyanate compound obtainable from an aliphatic isocyanate and/or an alicyclic isocyanate, a hydrophilic compound, an imidazole-based blocker (b1) represented by the formula (I) and a blocker (b2) other than (b1). Relative to 100 mol of isocyanate groups of the polyisocyanate compound, active hydrogen groups of the hydrophilic compound is 1 mol or more and 30 mol or less. The molar ratio of b1 to b2 (b1/b2) is 95/5-5/95.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a blocked polyisocyanate composition, a resin composition, a resin film and a laminate.

Conventionally, polyurethane resin paints have very good abrasion resistance, chemical resistance and stain resistance. In particular, polyurethane resin coatings using polyisocyanates obtained from aliphatic diisocyanates or alicyclic diisocyanates are more excellent in weather resistance, and their demand tends to increase. However, since polyurethane resin paints are generally two-component, their use is extremely inconvenient. That is, ordinary polyurethane resin paints are composed of two components, polyol and polyisocyanate, and it is necessary to store polyol and polyisocyanate separately and mix them at the time of painting. In addition, once the two are mixed, the paint gels in a short period of time and becomes unusable. Since polyurethane resin paints have such problems, they are extremely difficult to use for automatic painting in the field of line painting such as automobile painting or weak electric painting. In addition, isocyanate readily reacts with water, so that it cannot be used in water-based paints such as electrodeposition paints. Furthermore, when a paint containing isocyanate is used, it is necessary to thoroughly wash the coating machine and the coating tank after finishing the work, which significantly reduces the work efficiency.

In order to solve the above problems, it has been conventionally proposed to use a blocked polyisocyanate in which all active isocyanate groups are blocked with a blocking agent. This blocked polyisocyanate does not react with polyols at room temperature. However, the heating dissociates the blocking agent, regenerates the active isocyanate group, reacts with the polyol, and causes a cross-linking reaction, so that the above problem can be improved. Therefore, many blocking agents have been studied, and typical blocking agents include phenol and methyl ethyl ketoxime.

However, when blocked polyisocyanates containing these blocking agents are used, a baking temperature as high as 140° C. or higher is generally required. Requiring baking at a high temperature is not only disadvantageous in terms of energy, but also requires heat resistance of the base material, which is a factor limiting its application.

On the other hand, as a low-temperature baking type blocked polyisocyanate, studies have been made on blocked polyisocyanates using active methylene compounds such as acetoacetic esters and malonic acid diesters. For example, Patent Documents 1 and 2 propose blocked polyisocyanate compositions that cure at 90°C.

Moreover, from the viewpoint of global environmental protection, there is an increasing need for water-based resin compositions. In order to ensure dispersibility in the water-based resin composition, for example, Patent Document 3 discloses a technique of modifying a block polyisocyanate with a hydrophilic group to improve dispersibility in the water-based resin composition.
Patent Document 4 discloses, as a dissociation type blocked polyisocyanate, an imidazole-based blocked polyisocyanate composition modified with a nonionic hydrophilic group compound.

Japanese Patent Application Laid-Open No. 2002-322238 JP 2006-335954 A Japanese Patent No. 3947260 Japanese Patent No. 6025507

Physical properties required for block polyisocyanate include curability when baked at a low temperature of 90° C. or less, dispersibility in water-based resin compositions, and storage stability as water-based resin compositions. It also has water resistance when used as a coating film. However, it is very difficult to satisfy all of these.

The present invention has been made in view of the above circumstances, and has excellent dispersibility when made into a water-based resin composition, excellent pot life of the paint, and curability when baked at a low temperature of 90 ° C. or less. Provided are a blocked polyisocyanate composition which is excellent in water resistance when formed into a coating film, and a resin composition, a resin film and a laminate using the blocked polyisocyanate composition.

That is, the present invention includes the following aspects.
(1) Polyisocyanate compounds obtained from aliphatic isocyanates and/or alicyclic isocyanates, hydrophilic compounds, imidazole-based blocking agents (b1) having a structure represented by the following general formula (I) and blocking agents other than b1 (b2) containing a blocked polyisocyanate derived from (b2), the ratio of the active hydrogen groups of the hydrophilic compound to 100 mol of the isocyanate groups of the polyisocyanate compound is 1 mol or more and 30 mol or less, and the mol of b1 and b2 A blocked polyisocyanate composition having a ratio (b1/b2) of 95/5 to 5/95.

(In general formula (I), R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom or an alkyl optionally containing one or more substituents selected from the group consisting of a hydroxy group and an amino group. The total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is 1 or more and 20 or less.)

(2) The block polyisocyanate composition according to (1) above, wherein the hydrophilic compound is a polyoxyethylene compound having a number average molecular weight of 200 or more and 2,000 or less.
(3) The blocked polyisocyanate composition according to (1) or (2) above, wherein the blocking agent (b2) other than b1 is a pyrazole compound or an oxime compound.
(4) A resin composition comprising the blocked polyisocyanate composition according to any one of (1) to (3) above and a polyhydric hydroxy compound.
(5) A resin film obtained by curing the resin composition according to (4) above.
(6) A laminate obtained by laminating one or more layers of the resin film according to (5) above on a substrate, wherein the thickness of each layer of the resin film is 1 μm or more and 50 μm or less. body.

According to the blocked polyisocyanate composition of the above aspect, when it is made into a water-based resin composition, it has excellent dispersibility, excellent pot life of the coating, excellent curability when baked at a low temperature of 90 ° C. or less, and excellent coating. It is possible to provide a blocked polyisocyanate composition that is excellent in water resistance when formed into a film. A water-based resin composition containing the above-mentioned blocked polyisocyanate composition is excellent in low-temperature curability, and thus is suitable for coating materials with low heat resistance.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail. In addition, the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate changes within the scope of its gist.

As used herein, "polyol" means a compound having two or more hydroxy groups (--OH).
As used herein, "polyisocyanate" means a reactant in which a plurality of monomeric compounds having one or more isocyanate groups (--NCO) are bonded.

As used herein, the term "structural unit" means a structure resulting from one molecule of a monomer in a structure constituting a polyisocyanate or a blocked polyisocyanate. For example, a structural unit derived from a malonic acid ester indicates a structure resulting from one molecule of the malonic acid ester in the block polyisocyanate. The structural unit may be a unit directly formed by a (co)polymerization reaction of monomers, or may be a unit in which a part of the unit is converted to another structure by treating the (co)polymer. There may be.

<<Blocked polyisocyanate composition>>
Each component contained in the blocked polyisocyanate composition of the present embodiment will be described in detail below.

The blocked polyisocyanate composition of the present embodiment comprises a polyisocyanate compound obtained from an aliphatic isocyanate and/or an alicyclic isocyanate, a hydrophilic compound, and an imidazole-based blocking agent ( b1) and a blocked polyisocyanate derived from a blocking agent (b2) other than b1, wherein the proportion of active hydrogen groups of the hydrophilic compound is 1 mol or more and 30 mol or less with respect to 100 mol of isocyanate groups of the polyisocyanate compound. and the molar ratio (b1/b2) of b1 and b2 is 95/5 to 5/95.

(In general formula (I), R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom or an alkyl optionally containing one or more substituents selected from the group consisting of a hydroxy group and an amino group. The total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is 1 or more and 20 or less.)

[Hydrophilic compound]
The hydrophilic compound used in the blocked polyisocyanate composition is not particularly limited as long as it is a compound capable of imparting hydrophilicity to the blocked polyisocyanate composition. Examples include nonionic hydrophilic compounds, cationic hydrophilic compounds, and anionic hydrophilic compounds. compound. These hydrophilic compounds may be used singly or in combination of two or more. Among them, the hydrophilic compound is preferably a nonionic hydrophilic compound because it is excellent in dispersibility when used as a water-based resin composition.
As the hydrophilic compound, an anionic hydrophilic compound is preferable from the viewpoint of suppressing a decrease in hardness and strength of the resulting resin film and from the viewpoint of improving the emulsifiability.
These hydrophilic compounds have, in addition to the hydrophilic group, one or more active hydrogen groups for reacting with the isocyanate group per molecule of the hydrophilic compound. Specific examples of active hydrogen groups include hydroxyl groups, mercapto groups, carboxylic acid groups, amino groups, and thiol groups.

(Nonionic hydrophilic compound)
Specific examples of nonionic hydrophilic compounds include monoalcohols and compounds obtained by adding ethylene oxide to hydroxyl groups of alcohols. Monoalcohols include, for example, methanol, ethanol, butanol, and the like. Examples of the compound obtained by adding ethylene oxide to the hydroxyl group of alcohol include ethylene glycol, diethylene glycol, and polyethylene glycol.

Among them, polyethylene glycol monoalkyl ether obtained by adding ethylene oxide to the hydroxyl group of monoalcohol is preferable as the nonionic hydrophilic compound because it can improve the water dispersibility of the blocked polyisocyanate composition with a small amount used.

The addition number of ethylene oxide in the nonionic hydrophilic compound to which ethylene oxide is added is preferably 4 or more and 30 or less, more preferably 4 or more and 25 or less. When the number of ethylene oxide additions is at least the above lower limit, the blocked polyisocyanate composition tends to be more effectively imparted with water dispersibility. There is a tendency that deposits of the blocked polyisocyanate composition are less likely to occur during low-temperature storage.

(Cationic hydrophilic compound)
Specific examples of cationic hydrophilic compounds include compounds having both a cationic hydrophilic group and an active hydrogen group. A compound having an active hydrogen group such as a glycidyl group and a compound having a cationic hydrophilic group such as sulfide or phosphine may be combined as a hydrophilic compound. In this case, a compound having an isocyanate group and a compound having an active hydrogen group are reacted in advance to add a functional group such as a glycidyl group, and then a compound such as sulfide or phosphine is reacted. A compound having both a cationic hydrophilic group and an active hydrogen group is preferred from the viewpoint of ease of production.

Specific examples of compounds having both a cationic hydrophilic group and an active hydrogen group include dimethylethanolamine, diethylethanolamine, diethanolamine, and methyldiethanolamine. Tertiary amino groups added using these compounds can also be quaternized with, for example, dimethyl sulfate and diethyl sulfate.

The cationic hydrophilic compound and the aliphatic isocyanate and/or the alicyclic isocyanate can be reacted in the presence of a solvent. The solvent in this case preferably does not contain an active hydrogen group, and specific examples thereof include ethyl acetate, propylene glycol monomethyl ether acetate, dipropylene glycol dimethyl ether, and the like.

The cationic hydrophilic groups added to the blocked polyisocyanate are preferably neutralized with a compound having an anionic group. Specific examples of the anionic group include a carboxy group, a sulfonic acid group, a phosphoric acid group, a halogen group, and a sulfuric acid group.

Specific examples of compounds having a carboxy group include formic acid, acetic acid, propionic acid, butyric acid, and lactic acid.

Specific examples of compounds having a sulfonic acid group include ethanesulfonic acid and the like.

Specific examples of compounds having a phosphoric acid group include phosphoric acid and acidic phosphoric acid esters.

Specific examples of compounds having a halogen group include hydrochloric acid and the like.

Specific examples of compounds having a sulfate group include sulfuric acid.

Among them, the compound having an anionic group is preferably a compound having a carboxy group, and more preferably acetic acid, propionic acid or butyric acid.

(Anionic hydrophilic compound)
Specific examples of anionic hydrophilic groups include a carboxy group, a sulfonic acid group, a phosphoric acid group, a halogen group, and a sulfuric acid group.

Specific examples of anionic hydrophilic compounds include compounds having both an anionic group and an active hydrogen group. compounds having as a sexual group.

Examples of monohydroxycarboxylic acids include 1-hydroxyacetic acid, 3-hydroxypropanoic acid, 12-hydroxy-9-octadecanoic acid, hydroxypivalic acid (hydroxypivalic acid), lactic acid and the like.

Examples of compounds having a carboxy group of polyhydroxycarboxylic acid as an anionic group include dimethylolacetic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, dimethylolpropionic acid, and the like. .

Also included are compounds having both a sulfonic acid group and an active hydrogen group, more specifically, for example, isethionic acid.

Among them, hydroxypivalic acid or dimethylolpropionic acid is preferable as a compound having both an anionic group and an active hydrogen group.

The anionic hydrophilic group added to the blocked polyisocyanate is preferably neutralized with an amine compound, which is a basic substance.

Specific examples of amine compounds include ammonia and water-soluble amino compounds.

Specific examples of water-soluble amino compounds include monoethanolamine, ethylamine, dimethylamine, diethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, triethanolamine, butylamine, dibutylamine, 2- Ethylhexylamine, ethylenediamine, propylenediamine, methylethanolamine, dimethylethanolamine, diethylethanolamine, morpholine and the like. Further, tertiary amines such as triethylamine and dimethylethanolamine are also included, and these can also be used. These amine compounds may be used singly or in combination of two or more.

(Percentage of active hydrogen groups in hydrophilic compound)
In the blocked polyisocyanate composition of the present embodiment, the ratio of the active hydrogen groups of the hydrophilic compound to 100 mol of the isocyanate groups of the polyisocyanate compound is 1 mol or more and 30 mol or less. The hydrophilic group-modified amount of the polyisocyanate compound is such that the ratio of the active hydrogen groups of the hydrophilic compound is 1 mol or more and 30 mol or less with respect to 100 mol of the isocyanate groups. The modified amount is preferably 2 mol or more and 25 mol or less, more preferably 3 mol or more and 20 mol or less, and even more preferably 5 mol or more and 15 mol or less.
When the modified amount is 1 mol or more, the dispersibility of the water-based coating composition can be maintained well, and when it is 30 mol or less, the water resistance of the resulting coating film can be maintained well. can be done.

(Number average molecular weight of polyoxyethylene compound)
The hydrophilic compound used in the block polyisocyanate composition of the present embodiment is preferably a polyoxyethylene compound having a number average molecular weight of 200 or more and 2000 or less.
The number average molecular weight is more preferably 300 or more and 1500 or less, even more preferably 350 or more and 1200 or less, and most preferably 400 or more and 1000 or less.
When the number average molecular weight of the polyoxyethylene compound is 200 or more, the dispersibility of the aqueous coating composition can be maintained, and when it is 2000 or less, the water resistance of the resulting coating film is maintained well. be able to.
A "polyoxyethylene compound" means a hydrophilic compound to which ethylene oxide is added, and is preferably a nonionic hydrophilic compound to which ethylene oxide is added.

<Blocking agent component>
The blocked polyisocyanate composition is a block polyisocyanate compound derived from a polyisocyanate compound, a hydrophilic compound, an imidazole-based blocking agent (b1) having a structure represented by the following general formula (I), and a blocking agent (b2) other than b1. It contains isocyanate and the molar ratio of b1 and b2 (b1/b2) is from 95/5 to 5/95.

[Imidazole-based blocking agent (b1)]
A blocked polyisocyanate component is formed by blocking with an imidazole-based blocking agent (b1) represented by the following general formula (I).

(In general formula (I), R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom or an alkyl optionally containing one or more substituents selected from the group consisting of a hydroxy group and an amino group. The total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is 1 or more and 20 or less.)

(R ¹¹ , R ¹² and R ¹³ )
From the viewpoint of compatibility, the alkyl group for R ¹¹ , R ¹² and R ¹³ preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and 1 to 6 carbon atoms. is more preferable, and 1 or more and 4 or less is particularly preferable.

Specific examples of alkyl groups having no substituents include methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, isobutyl and n-pentyl groups. , isopentyl group, neopentyl group, tert-pentyl group, 1-methylbutyl group, n-hexyl group, 2-methylpentyl group, 3-methylpentyl group, 2,2-dimethylbutyl group, 2,3-dimethylbutyl group, n-heptyl group, 2-methylhexyl group, 3-methylhexyl group, 2,2-dimethylpentyl group, 2,3-dimethylpentyl group, 2,4-dimethylpentyl group, 3,3-dimethylpentyl group, 3 -ethylpentyl group, 2,2,3-trimethylbutyl group, n-octyl group, isooctyl group, 2-ethylhexyl group, nonyl group, decyl group and the like.

When R ¹¹ , R ¹² and R ¹³ are substituted alkyl groups, the substituents are hydroxy or amino groups.

Examples of the alkyl group containing a hydroxy group as a substituent include a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group and the like.

Examples of the alkyl group containing an amino group as a substituent include aminomethyl group, aminoethyl group, aminopropyl group, aminobutyl group and the like.

Alkyl groups containing a hydroxy group and an amino group as substituents include, for example, a hydroxyaminomethyl group, a hydroxyaminoethyl group, and a hydroxyaminopropyl group.

Among them, from the viewpoint of compatibility of the blocked polyisocyanate composition, one or more of R ¹¹ , R ¹² and R ¹³ is preferably an alkyl group, and from the viewpoint of low-temperature curability, only R ¹¹ is an alkyl group. is more preferable. Further, from the viewpoint of industrial availability, it is more preferable that R ¹² and R ¹³ are hydrogen atoms and R ¹¹ is a methyl group or an ethyl group.

[Blocking agents other than b1 (b2)]
The blocking agent (b2) other than b1 used in the blocked polyisocyanate composition is a dissociation type blocking agent other than imidazole compounds.

More specifically, the following are mentioned.
1) triazole compounds, 2) pyrazole compounds, 3) alcohol compounds, 4) alkylphenol compounds, 5) phenol compounds, 6) mercaptan compounds, 7) acid amide compounds, 8) acid imide compounds, 9) urea-based compounds, 10) oxime-based compounds, 11) amine-based compounds, 12) imine-based compounds, 13) bisulfites, and the like. These blocking agents may be used alone or in combination of two or more.

1) Triazole compounds: 1,2,4-triazole, 1,2,3-triazole.
2) Pyrazole compounds: pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole.
3) alcohol compounds: alcohols such as methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol;

4) Alkylphenol compounds: mono- and dialkylphenols having alkyl groups of 4 or more carbon atoms as substituents. Specific examples of alkylphenol compounds include n-propylphenol, iso-propylphenol, n-butylphenol, sec-butylphenol, tert-butylphenol, n-hexylphenol, 2-ethylhexylphenol, n-octylphenol and n-nonylphenol. monoalkylphenols such as di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol, di-tert-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, dialkylphenols such as di-n-nonylphenol;

5) Phenolic compounds: phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester and the like.
6) Mercaptan compounds: butyl mercaptan, dodecyl mercaptan and the like.
7) Acid amide compounds: acetanilide, acetic amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam and the like.
8) Acid imide compounds: succinimide, maleic imide and the like.
9) Urea-based compounds: urea, thiourea, ethylene urea, and the like.

10) Oxime compounds: formaldoxime, acetoaldoxime, acetoxime, methylethylketoxime, cyclohexanone oxime and the like.
11) Amine compounds: diphenylamine, aniline, carbazole, di-n-propylamine, diisopropylamine, isopropylethylamine and the like.
12) imine compounds: ethyleneimine, polyethyleneimine and the like;
13) Bisulfite compounds: sodium bisulfite and the like.

Among them, 1) triazole-based compounds, 2) pyrazole-based compounds, and 10) oxime-based compounds are preferable, and 2) pyrazole-based compounds and 10) oxime-based compounds are more preferable from the viewpoint of low-temperature curability and dispersibility. 2) pyrazole-based compounds are even more preferred.
Among pyrazole compounds, 3-methylpyrazole and 3,5-dimethylpyrazole are preferred, and 3,5-dimethylpyrazole is more preferred.

[Other blocking agents]
As the blocking agent, in addition to the blocking agent (b1) and the blocking agent (b2) described above, within a range that does not hinder the storage stability of the resin composition and the low-temperature curability of the resin film, Other blocking agents may be included.

Other blocking agents include active methylene compounds. Specific examples of the blocking agent include those shown below. These blocking agents may be used alone or in combination of two or more.

More specifically, the following are mentioned.
Active methylene compounds: malonic diesters (dimethyl malonate, diethyl malonate, diisopropyl malonate, di-t-butyl malonate), acetoacetates (methyl acetoacetate, ethyl acetoacetate, methyl isobutanoyl acetate, ethyl isobutanoyl acetate) ), acetylacetone and the like.

[b1/b2 molar ratio]
The molar ratio of imidazole-based blocking agent (b1) and blocking agent (b2) other than b1, which are blocking agents used in the blocked polyisocyanate composition, is b1/b2=95/5 to 5/95. Preferably, it is from 93/7 to 30/70, even more preferably from 90/10 to 50/50, most preferably from 85/15 to 70/30.

<Polyisocyanate>
The polyisocyanate used in the blocked polyisocyanate composition of the present embodiment is obtained by reacting a plurality of monomer compounds (hereinafter sometimes referred to as "isocyanate monomers") having one or more isocyanate groups (--NCO). The resulting reactant.

As the isocyanate monomer, those having 4 to 30 carbon atoms are preferable. Specific examples of isocyanate monomers include the following. These isocyanate monomers may be used alone or in combination of two or more.

(1) 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (hereinafter sometimes referred to as "HDI"), 2,2,4-trimethyl-1,6-diisocyanatohexane, 2, Aliphatic diisocyanates such as 4,4-trimethyl-1,6-hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate (MPDI) and lysine diisocyanate (hereinafter sometimes referred to as "LDI").
(2) Fats such as isophorone diisocyanate (hereinafter sometimes referred to as "IPDI"), 1,3-bis(diisocyanatomethyl)cyclohexane, 4,4'-dicyclohexylmethane diisocyanate, diisocyanatonorbornane, di(isocyanatomethyl)norbornane, etc. Cyclic diisocyanate.
(3) 4-isocyanatomethyl-1,8-octamethylene diisocyanate (hereinafter sometimes referred to as "NTI"), 1,3,6-hexamethylene triisocyanate (hereinafter sometimes referred to as "HTI") , bis(2-isocyanatoethyl) 2-isocyanatoglutarate (hereinafter sometimes referred to as "GTI"), lysine triisocyanate (hereinafter sometimes referred to as "LTI") and other aliphatic triisocyanates and / or an alicyclic triisocyanate.

In the present invention, the isocyanate monomer is an aliphatic isocyanate and/or an alicyclic isocyanate, preferably an aliphatic diisocyanate and/or an alicyclic diisocyanate. By using an aliphatic isocyanate and/or an alicyclic isocyanate as the isocyanate monomer, a coating film having excellent weather resistance can be obtained. As the isocyanate monomer, HDI or IPDI is more preferable from the viewpoint of industrial availability. Moreover, as the isocyanate monomer, HDI is more preferable from the viewpoint of making the block polyisocyanate component low in viscosity.

In addition, as the isocyanate monomer used for producing the polyisocyanate, either an aliphatic isocyanate or an alicyclic isocyanate may be used alone, or an aliphatic diisocyanate or an alicyclic diisocyanate may be used alone. However, it is preferable to use an aliphatic diisocyanate and an alicyclic diisocyanate in combination, and it is particularly preferable to use HDI and IPDI. By using an aliphatic diisocyanate and an alicyclic diisocyanate, the toughness and hardness of a coating film can be further improved.

In the polyisocyanate, from the viewpoint of improving the coating film hardness and strength, the mass ratio of the structural unit derived from the aliphatic isocyanate to the structural unit derived from the alicyclic isocyanate (structural unit derived from the aliphatic isocyanate / to the alicyclic isocyanate derived structural unit) is preferably 50/50 or more and 95/5 or less, more preferably 55/45 or more and 93/7 or less, further preferably 60/40 or more and 91/9 or less, and 65/35 or more and 90/10 or less. is more preferred.
When the mass ratio of the structural unit derived from the aliphatic isocyanate to the structural unit derived from the alicyclic isocyanate is at least the above lower limit, the decrease in flexibility when used as a coating film is more effectively suppressed. can do. On the other hand, when it is equal to or less than the above upper limit, the hardness of the coating film can be further improved.

The mass ratio of structural units derived from an aliphatic isocyanate to structural units derived from an alicyclic isocyanate can be calculated, for example, using the following method. First, from the unreacted isocyanate mass after the reaction and the aliphatic isocyanate concentration and the alicyclic isocyanate concentration in this unreacted isocyanate obtained by gas chromatographic measurement, the mass of the unreacted aliphatic isocyanate and the unreacted alicyclic isocyanate Calculate the mass of Then, after subtracting the mass of the unreacted aliphatic isocyanate and the mass of the unreacted alicyclic isocyanate calculated above from the mass of the charged aliphatic isocyanate and the mass of the alicyclic isocyanate, respectively, the difference obtained is The mass of structural units derived from group isocyanates and the mass of structural units derived from alicyclic isocyanates. Then, by dividing the mass of the structural unit derived from the aliphatic isocyanate by the mass of the structural unit derived from the alicyclic isocyanate, the mass of the structural unit derived from the aliphatic isocyanate relative to the structural unit derived from the alicyclic isocyanate A ratio is obtained.

(polyol)
The polyisocyanate is preferably derived from the isocyanate monomer described above and a polyol having an average hydroxyl functional group number of 3.0 or more and 8.0 or less. Thereby, the average number of isocyanate groups of the resulting polyisocyanate can be increased. In the polyisocyanate, urethane groups are formed by reaction between the hydroxyl groups of the polyol and the isocyanate groups of the isocyanate monomer.

The average hydroxyl functional group number of the polyol is preferably 3.0 or more and 8.0 or less, more preferably 3 or more and 6 or less, still more preferably 3 or more and 5 or less, and particularly preferably 3 or 4. The average hydroxyl functional group number of polyol as used herein is the number of hydroxyl groups present in one polyol molecule.

The number average molecular weight of the polyol is preferably 100 or more and 1000 or less, preferably 100 or more and 900 or less, more preferably 100 or more and 600 or less, more preferably 100 or more and 570 or less, more preferably 100 or more, from the viewpoint of improving the coating film hardness and strength. It is more preferably 500 or less, even more preferably 100 or more and 400 or less, particularly preferably 100 or more and 350 or less, and most preferably 100 or more and 250 or less.
When the number average molecular weight of the polyol is within the above range, the blocked polyisocyanate composition is excellent in low-temperature curability when used as a coating film, and is particularly excellent in hardness and strength. The number average molecular weight Mn of the polyol is, for example, a polystyrene-based number average molecular weight measured by GPC.

Such polyols include, for example, trimethylolpropane, glycerol, and polycaprolactone polyols derived from trihydric or higher polyhydric alcohols and ε-caprolactone.

Examples of commercially available polycaprolactone polyols include Daicel's "PLAXEL 303" (number average molecular weight: 300), "PLAXEL 305" (number average molecular weight: 550), "PLAXEL 308" (number average molecular weight: 850), and "PLAXEL 309". ” (number average molecular weight 900).

(Method for producing polyisocyanate)
The details of the method for producing the polyisocyanate are described below.
Polyisocyanate is, for example, an allophanatization reaction to form an allophanate group, an uretdiionization reaction to form an uretdione group, an iminooxadiazinedionization reaction to form an iminooxadiazinedione group, and an isocyanurate reaction to form an isocyanurate group. A reaction, a urethanization reaction to form a urethane group, and a biuretization reaction to form a biuret group are produced at once in the presence of excess isocyanate monomer, and after completion of the reaction, unreacted isocyanate monomer is removed. be able to. That is, the polyisocyanate obtained by the above reaction is one in which a plurality of the above-mentioned isocyanate monomers are bonded, and the group consisting of allophanate group, uretdione group, iminooxadiazinedione group, isocyanurate group, urethane group and biuret group It is a reactant having one or more selected from.
Alternatively, the above reactions may be carried out separately and the resulting polyisocyanates may be mixed in specific proportions.
For ease of production, it is preferable to carry out the above reaction at once to obtain a polyisocyanate, and from the viewpoint of freely adjusting the molar ratio of each functional group, it is preferable to mix after producing separately.

(1) Method for producing allophanate group-containing polyisocyanate Allophanate group-containing polyisocyanate is obtained by adding an alcohol to an isocyanate monomer and using an allophanatization reaction catalyst.
Alcohols used to form allophanate groups are preferably alcohols formed only from carbon, hydrogen and oxygen.
Specific examples of the alcohol include, but are not limited to, monoalcohols, dialcohols, and the like. These alcohols may be used individually by 1 type, and may be used in combination of 2 or more types.
Examples of monoalcohols include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol and the like.
Examples of dialcohols include ethylene glycol, 1,3-butanediol, neopentyl glycol, 2-ethylhexanediol and the like.
Among them, the alcohol is preferably a monoalcohol, more preferably a monoalcohol having a molecular weight of 200 or less.

Examples of the allophanatization reaction catalyst include, but are not limited to, alkyl carboxylates of tin, lead, zinc, bismuth, zirconium, zirconyl, and the like.
Examples of alkyl carboxylates of tin (organotin compounds) include tin 2-ethylhexanoate and dibutyltin dilaurate.
Examples of lead alkyl carboxylates (organic lead compounds) include lead 2-ethylhexanoate.
Examples of zinc alkylcarboxylates (organozinc compounds) include zinc 2-ethylhexanoate and the like.
Bismuth alkyl carboxylates include, for example, bismuth 2-ethylhexanoate.
Examples of alkyl carboxylates of zirconium include zirconium 2-ethylhexanoate and the like.
Alkyl carboxylates of zirconyl include, for example, zirconyl 2-ethylhexanoate. These catalysts can be used alone or in combination of two or more.
In addition, an isocyanurate-forming reaction catalyst, which will be described later, can also be an allophanat-forming reaction catalyst. When the allophanatization reaction is performed using the isocyanurate reaction catalyst described later, an isocyanurate group-containing polyisocyanate (hereinafter sometimes referred to as "isocyanurate-type polyisocyanate") is naturally produced.
Among them, it is preferable from the standpoint of economic production to perform the allophanatization reaction and the isocyanuration reaction using an isocyanuration reaction catalyst, which will be described later, as the allophanatization reaction catalyst.

The lower limit of the amount of the allophanatization reaction catalyst described above is preferably 10 mass ppm, more preferably 20 mass ppm, and 40 mass ppm relative to the mass of the charged isocyanate monomer. More preferably, it is particularly preferably 80 mass ppm.
The upper limit of the amount of the allophanatization reaction catalyst described above is preferably 1000 mass ppm, more preferably 800 mass ppm, and 600 mass ppm relative to the mass of the charged isocyanate monomer. More preferably, it is particularly preferably 500 mass ppm.
That is, the amount of the allophanate reaction catalyst used is preferably 10 mass ppm or more and 1000 mass ppm or less, and more preferably 20 mass ppm or more and 800 mass ppm or less, relative to the mass of the charged isocyanate monomer. It is preferably 40 mass ppm or more and 600 mass ppm or less, and particularly preferably 80 mass ppm or more and 500 mass ppm or less.

The lower limit of the allophanatization reaction temperature is preferably 40°C, more preferably 60°C, still more preferably 80°C, and particularly preferably 100°C.
The upper limit of the allophanatization reaction temperature is preferably 180°C, more preferably 160°C, and even more preferably 140°C.
That is, the allophanatization reaction temperature is preferably 40 ° C. or higher and 180 ° C. or lower, more preferably 60 ° C. or higher and 160 ° C. or lower, further preferably 80 ° C. or higher and 140 ° C. or lower, and 100 ° C. or higher. 140° C. or lower is particularly preferable.
When the allophanatization reaction temperature is at least the above lower limit, it is possible to further improve the reaction rate. When the allophanatization reaction temperature is equal to or lower than the above upper limit, it tends to be possible to more effectively suppress the coloring of the polyisocyanate.

(2) Method for producing uretdione group-containing polyisocyanate When a polyisocyanate having uretdione groups is derived from an isocyanate monomer, for example, the isocyanate monomer is multimerized using a uretdione reaction catalyst or by heat. can be manufactured.
The uretdione reaction catalyst is not particularly limited, but examples thereof include tertiary phosphines such as trialkylphosphine, tris(dialkylamino)phosphine and cycloalkylphosphine, and Lewis acids.
Examples of trialkylphosphine include tri-n-butylphosphine and tri-n-octylphosphine.
Examples of tris(dialkylamino)phosphine include tris-(dimethylamino)phosphine and the like.
Cycloalkylphosphine includes, for example, cyclohexyl-di-n-hexylphosphine.
Lewis acids include, for example, boron trifluoride and zinc oxychloride.

Many of the uretdiionization reaction catalysts can also promote the isocyanuration reaction at the same time.
When a uretdione reaction catalyst is used, the uretdione reaction catalyst can be stopped by adding a deactivator for the uretdione reaction catalyst such as phosphoric acid or methyl p-toluenesulfonate when the desired yield is achieved. preferable.
When obtaining a polyisocyanate having a uretdione group by heating one or more diisocyanates selected from the group consisting of the aliphatic diisocyanates and the alicyclic diisocyanates without using a uretdione reaction catalyst, the heating temperature is , 120° C. or higher, and more preferably 150° C. or higher and 170° C. or lower. Moreover, the heating time is preferably 1 hour or more and 4 hours or less.

(3) Method for producing iminooxadiazinedione group-containing polyisocyanate When an iminooxadiazinedione group-containing polyisocyanate is derived from an isocyanate monomer, an iminooxadiazinedione reaction catalyst is usually used.
Examples of iminooxadiazine dionization catalysts include those shown in 1) or 2) below.

1) A (poly)hydrogen fluoride compound represented by the general formula M[F _n ] or M[F _n (HF) _m ].
(Where m and n are integers satisfying the relationship m/n>0. M is an n-charged cation (mixture) or one or more radicals with a total of n valences.)

2) a compound represented by the general formula R ¹ -CR' ₂ -C(O)O- or the general formula R ² =CR'-C(O)O- and a quaternary ammonium cation or and a quaternary phosphonium cation.
(wherein R ¹ is a linear, branched or cyclic saturated or unsaturated perfluoroalkyl group having 1 to 30 carbon atoms; R ² is a linear, branched or cyclic , a saturated or unsaturated perfluoroalkylidene group having 1 to 30 carbon atoms, and a plurality of R' are each independently a hydrogen atom, or an alkyl group or aryl having 1 to 20 carbon atoms which may contain a heteroatom. base.)

Specific examples of the compound ((poly)hydrogen fluoride compound) of 1) include tetramethylammonium fluoride hydrate and tetraethylammonium fluoride.
Specific examples of the compound of 2) include 3,3,3-trifluorocarboxylic acid, 4,4,4,3,3-pentafluorobutanoic acid, 5,5,5,4,4,3, 3-heptafluoropentanoic acid, 3,3-difluoroprop-2-enoic acid and the like.
Among them, as the iminooxadiazine dionization reaction catalyst, 1) is preferable from the viewpoint of availability, and 2) is preferable from the viewpoint of safety.

The lower limit of the amount of the iminooxadiazine dionization catalyst to be used is not particularly limited, but from the viewpoint of reactivity, it is preferably 5 ppm, more preferably 10 ppm, in mass ratio relative to the raw material isocyanate monomer such as HDI. , 20 ppm is more preferred.
The upper limit of the amount of the iminooxadiazine dionization catalyst to be used is preferably 5000 ppm in mass ratio with respect to the raw material isocyanate monomer such as HDI from the viewpoint of suppressing coloring and discoloration of the product and controlling the reaction. 2000 ppm is more preferred, and 500 ppm is even more preferred.
That is, the amount of the iminooxadiazine dionization catalyst used is preferably 5 ppm or more and 5000 ppm or less, more preferably 10 ppm or more and 2000 ppm or less, and 20 ppm or more in terms of mass ratio with respect to the raw material isocyanate monomer such as HDI. 500 ppm or less is more preferable.

Although the lower limit of the reaction temperature for iminooxadiazine dionization is not particularly limited, it is preferably 40°C, more preferably 50°C, and even more preferably 60°C from the viewpoint of reaction rate.
The upper limit of the reaction temperature for iminooxadiazine dionization is preferably 150°C, more preferably 120°C, and even more preferably 110°C, from the viewpoint of suppressing coloring and discoloration of the product.
That is, the reaction temperature for iminooxadiazine dionization is preferably 40° C. or higher and 150° C. or lower, more preferably 50° C. or higher and 120° C. or lower, even more preferably 60° C. or higher and 110° C. or lower.

Once the iminooxadiazinedione formation reaction reaches the desired iminooxadiazinedione group content, the iminooxadiazinedione formation reaction can be stopped. The iminooxadiazine dionization reaction can be terminated, for example, by adding an acidic compound to the reaction solution. Examples of acidic compounds include phosphoric acid, acidic phosphate esters, sulfuric acid, hydrochloric acid, and sulfonic acid compounds. As a result, the iminooxadiazine dionization reaction catalyst is neutralized or deactivated by thermal decomposition, chemical decomposition, or the like. After stopping the reaction, if necessary, perform filtration.

(4) Method for Producing Isocyanurate Group-Containing Polyisocyanate The catalyst for deriving the isocyanurate group-containing polyisocyanate from the isocyanate monomer includes commonly used isocyanurate reaction catalysts.

Although the isocyanurate-forming reaction catalyst is not particularly limited, it is generally preferred to have basicity. Specific examples of the isocyanurate reaction catalyst include those shown below.
1) Hydroxides of tetraalkylammonium such as tetramethylammonium, tetraethylammonium and tetrabutylammonium, and acetates, propionates, octylates, caprates, myristates and benzoates of the tetraalkylammonium Weak organic acid salts such as
2) Hydroxides of aryltrialkylammonium such as benzyltrimethylammonium and trimethylphenylammonium, and acetates, propionates, octylates, caprates, myristates, benzoates, etc. of the above aryltrialkylammoniums organic weak acid salt of .
3) Hydroxides of hydroxyalkylammonium such as trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium and triethylhydroxypropylammonium, and acetates, propionates, octylates and capric acid of said hydroxyalkylammoniums Organic weak acid salts such as salt, myristate, benzoate and the like.
4) Metal salts such as tin, zinc and lead of alkylcarboxylic acids such as acetic acid, propionic acid, caproic acid, octylic acid, capric acid and myristic acid.
5) Metal alcoholates such as sodium and potassium.
6) Aminosilyl group-containing compounds such as hexamethylenedisilazane.
7) Mannich bases.
8) Mixtures of tertiary amines and epoxy compounds.
9) Phosphorus compounds such as tributylphosphine.

Among them, the isocyanurate-forming reaction catalyst is preferably a quaternary ammonium hydroxide or a quaternary ammonium organic weak acid salt, from the viewpoint of less generation of unnecessary by-products, tetraalkylammonium hydroxide, More preferably, it is a weak organic acid salt of tetraalkylammonium, a hydroxide of aryltrialkylammonium, or a weak organic acid salt of aryltrialkylammonium.

The upper limit of the amount of the isocyanurate reaction catalyst used is preferably 1000 ppm by mass, more preferably 500 ppm by mass, and 100 ppm by mass relative to the mass of the charged isocyanate monomer. is more preferred.
On the other hand, the lower limit of the amount of the isocyanurate reaction catalyst used is not particularly limited, but may be, for example, 10 mass ppm.

The isocyanurate-forming reaction temperature is preferably 50° C. or higher and 120° C. or lower, more preferably 60° C. or higher and 90° C. or lower. When the isocyanurate-forming reaction temperature is equal to or lower than the above upper limit, it tends to be possible to more effectively suppress the coloring of the polyisocyanate.

When the desired conversion rate (ratio of the mass of the polyisocyanate produced in the isocyanurate reaction to the mass of the charged isocyanate monomer) is reached, the isocyanurate reaction is performed with an acidic compound (e.g., phosphoric acid, acidic phosphoric acid ester, etc.).
In addition, in order to obtain a polyisocyanate, it is necessary to stop the progress of the reaction at an early stage. However, since the initial reaction rate of the isocyanurate reaction is very fast, it is difficult to stop the progress of the reaction at an early stage, and it is necessary to carefully select the reaction conditions, especially the amount and method of addition of the catalyst. be. For example, a method of adding the catalyst in portions at fixed time intervals is recommended as a suitable method.

Therefore, the conversion rate of the isocyanurate reaction for obtaining the polyisocyanate is preferably 10% or more and 60% or less, more preferably 15% or more and 55% or less, and 20% or more and 50% or less. is more preferred.
The block polyisocyanate component can have a lower viscosity when the conversion rate of the isocyanurate-forming reaction is equal to or lower than the above upper limit. Further, when the conversion rate of the isocyanurate-forming reaction is equal to or higher than the above lower limit, the reaction termination operation can be performed more easily.

Moreover, when deriving a polyisocyanate containing an isocyanurate group, an alcohol having a valence of 1 or more and 6 or less can be used in addition to the isocyanate monomer.
Examples of usable monovalent to hexavalent alcohols include non-polymerizable alcohols and polymerizable alcohols. "Non-polymerizable alcohol" as used herein means an alcohol having no polymerizable group. On the other hand, "polymerizable alcohol" means an alcohol obtained by polymerizing a monomer having a polymerizable group and a hydroxyl group.

Examples of non-polymerizable alcohols include polyhydric alcohols such as monoalcohols, diols, triols, and tetraols.
Examples of monoalcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, n-hexanol, n-octanol, n-nonanol, and 2-ethylbutanol. , 2,2-dimethylhexanol, 2-ethylhexanol, cyclohexanol, methylcyclohexanol, ethylcyclohexanol, and the like.
Diols include, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1, 3-butanediol, 1,4-butanediol, 2,3-butanediol, 2-methyl-1,2-propanediol, 1,5-pentanediol, 2-methyl-2,3-butanediol, 1, 6-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2-methyl-2,4-pentanediol, 2,3-dimethyl-2,3-butanediol, 2-ethyl-hexanediol, 1,2-octanediol, 1,2-decanediol, 2,2,4-trimethylpentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propane and diols.
Examples of triols include glycerin and trimethylolpropane.
Examples of tetraols include pentaerythritol and the like.

Examples of the polymerizable alcohol include, but are not particularly limited to, polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, and the like.

Examples of polyester polyols include, but are not particularly limited to, products obtained by a condensation reaction between a dibasic acid alone or in mixture and a polyhydric alcohol alone or in mixture.
The dibasic acid is not particularly limited, but for example, at least one selected from the group consisting of carboxylic acids such as succinic acid, adipic acid, sebacic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, and terephthalic acid. species diacids.
Examples of polyhydric alcohols include, but are not limited to, at least one polyhydric alcohol selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, trimethylolpropane, and glycerin.
Examples of polyester polyols include polycaprolactones obtained by ring-opening polymerization of ε-caprolactone using the polyhydric alcohol.

The polyether polyols are not particularly limited, but for example, an alkali metal hydroxide or a strongly basic catalyst is used to add an alkylene oxide alone or a mixture to a polyhydric alcohol alone or in a mixture. polyether polyols obtained by reacting polyamine compounds with alkylene oxides, and so-called polymer polyols obtained by polymerizing acrylamide or the like using the above polyethers as a medium.

Alkali metals include, for example, lithium, sodium, potassium and the like.

Examples of strongly basic catalysts include alcoholates, alkylamines, and the like.

Examples of the polyhydric alcohol include those exemplified in the above polyester polyols.

Examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide.

Examples of polyamine compounds include ethylenediamines and the like.

The acrylic polyols are not particularly limited. or copolymerized with a mixture.

Examples of ethylenically unsaturated bond-containing monomers having a hydroxyl group include, but are not limited to, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxy methacrylate butyl and the like.

Other ethylenically unsaturated bond-containing monomers copolymerizable with the ethylenically unsaturated bond-containing monomer having a hydroxyl group are not particularly limited, but examples include acrylic acid esters, methacrylic acid esters, and unsaturated carboxylic acids. , unsaturated amides, vinyl-based monomers, and vinyl-based monomers having a hydrolyzable silyl group.

Examples of acrylic esters include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, and 2-acrylate. -ethylhexyl, lauryl acrylate, benzyl acrylate, phenyl acrylate and the like.

Examples of methacrylates include methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, methacrylate-2. -ethylhexyl, lauryl methacrylate, benzyl methacrylate, phenyl methacrylate and the like.

Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, and itaconic acid.

Examples of unsaturated amides include acrylamide, methacrylamide, N,N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, maleic acid amide, and maleimide.

Examples of vinyl-based monomers include glycidyl methacrylate, styrene, vinyl toluene, vinyl acetate, acrylonitrile, dibutyl fumarate and the like.

Vinyl monomers having a hydrolyzable silyl group include, for example, vinyltrimethoxysilane, vinylmethyldimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, and the like.

Polyolefin polyols include, for example, hydroxyl-terminated polybutadiene and hydrogenated products thereof.

(5) Method for producing urethane group-containing polyisocyanate When deriving a polyisocyanate containing a urethane group from an isocyanate monomer, for example, an excess isocyanate monomer, the above polyol, and, if necessary, an alcohol other than the above polyol, can be produced by mixing and, if necessary, adding a urethanization reaction catalyst.

Examples of the polyol include those exemplified in the above "polyol".

Examples of alcohols other than the polyol include those exemplified in the above "Method for producing isocyanurate group-containing polyisocyanate" excluding those exemplified in the above "polyol".

The urethanization reaction catalyst is not particularly limited, but examples thereof include tin-based compounds, zinc-based compounds, and amine-based compounds.

The urethanization reaction temperature is preferably 50° C. or higher and 160° C. or lower, more preferably 60° C. or higher and 120° C. or lower.

When the urethanization reaction temperature is equal to or lower than the above upper limit, it tends to be possible to more effectively suppress the coloring of the polyisocyanate.

The urethanization reaction time is preferably 30 minutes or more and 4 hours or less, more preferably 1 hour or more and 3 hours or less, and even more preferably 1 hour or more and 2 hours or less.

The ratio of the molar amount of isocyanate groups of the isocyanate monomer to the molar amount of hydroxyl groups of the polyol (and alcohol other than the polyol, if necessary) is preferably 2/1 or more and 50/1 or less. When the molar ratio is equal to or higher than the above lower limit, the viscosity of the polyisocyanate can be made lower. When the molar ratio is equal to or less than the above upper limit, the yield of the urethane group-containing polyisocyanate can be further increased.

(6) Method for producing biuret group-containing polyisocyanate The biuret agent for deriving a biuret group-containing polyisocyanate from an isocyanate monomer is not particularly limited, but examples include water, monohydric tertiary alcohol, and formic acid. , organic primary monoamines, organic primary diamines, and the like.
The amount of isocyanate groups is preferably 6 mol or more, more preferably 10 mol or more, and even more preferably 10 mol or more and 80 mol or less per 1 mol of the biuretizing agent. If the molar amount of isocyanate groups per 1 mol of the biuretizing agent is at least the above lower limit, the polyisocyanate will have a sufficiently low viscosity, and if it is below the above upper limit, the low-temperature curability of the resin film will be further improved. do.

A solvent may also be used during the biuret-forming reaction. Any solvent may be used as long as it dissolves the isocyanate monomer and the biuretizing agent such as water and forms a homogeneous phase under the reaction conditions.

Specific examples of the solvent include ethylene glycol-based solvents and phosphoric acid-based solvents.

Examples of ethylene glycol solvents include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol mono-n-butyl ether acetate, and ethylene glycol. Diacetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, ethylene glycol di-n-butyl ether, ethylene glycol methyl ethyl ether, ethylene glycol methyl isopropyl ether, ethylene glycol methyl- n-butyl ether, ethylene glycol ethyl-n-propyl ether, ethylene glycol ethyl isopropyl ether, ethylene glycol ethyl-n-butyl ether, ethylene glycol-n-propyl-n-butyl ether, ethylene glycol isopropyl-n-butyl ether, diethylene glycol monomethyl ether acetate , diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-propyl ether acetate, diethylene glycol monoisopropyl ether acetate, diethylene glycol mono-n-butyl ether acetate, diethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether, diethylene glycol Diisopropyl ether, diethylene glycol di-n-butyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl isopropyl ether, diethylene glycol methyl-n-propyl ether, diethylene glycol methyl-n-butyl ether, diethylene glycol ethyl isopropyl ether, diethylene glycol ethyl-n-propyl ether, diethylene glycol ethyl -n-butyl ether, diethylene glycol-n-propyl-n-butyl ether, diethylene glycol isopropyl-n-butyl ether and the like.

Examples of phosphoric acid solvents include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tributyl phosphate.

These solvents may be used alone or in combination of two or more.
Among them, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate and diethylene glycol dimethyl ether are preferable as the ethylene glycol solvent.

Moreover, trimethyl phosphate or triethyl phosphate is preferable as the phosphoric acid-based solvent.

The biuret-forming reaction temperature is preferably 70° C. or higher and 200° C. or lower, more preferably 90° C. or higher and 180° C. or lower. When the content is equal to or less than the above upper limit, there is a tendency that the coloring of the polyisocyanate can be prevented more effectively.

The allophanatization reaction, uretodionization reaction, iminooxadiazinedionization reaction, isocyanurate reaction, urethanization reaction, and biuretization reaction described above may be carried out sequentially, or some of them may be carried out in parallel. good too.
The polyisocyanate can be obtained by removing the unreacted isocyanate monomer from the reaction solution after completion of the reaction by thin film distillation, extraction, or the like.

Moreover, for the purpose of suppressing coloration during storage, an antioxidant or an ultraviolet absorber may be added to the obtained polyisocyanate.
Examples of antioxidants include hindered phenols such as 2,6-di-tert-butyl-p-cresol. Examples of ultraviolet absorbers include benzotriazole and benzophenone. These antioxidants and UV absorbers may be used alone or in combination of two or more. The amount of these added is preferably 10 mass ppm or more and 500 mass ppm or less with respect to the mass of the polyisocyanate.

(Average number of isocyanate groups of polyisocyanate)
The average number of isocyanate groups of the polyisocyanate used in the present embodiment is preferably 2.0 or more in terms of improving the low-temperature curability when forming a resin film, and the low-temperature curability and polyvalent 3.0 or more and 20.0 or less are more preferable, 3.2 or more and 10.0 or less are still more preferable, and 3.4 or more and 8.0 or less are particularly preferable, from the viewpoint of compatibility with the hydroxy compound. 5 or more and 6.0 or less is most preferable.
The average number of isocyanate functional groups of the polyisocyanate can be measured using the method described in Examples below.

[Method for producing blocked polyisocyanate composition]
Although the blocked polyisocyanate composition of the present embodiment is not particularly limited, the polyisocyanate compound, the hydrophilic compound, the imidazole-based blocking agent (b1) having the structure represented by the general formula (I), and blocks other than b1 It is obtained by reacting the agents (b2) respectively.

The reaction between the polyisocyanate and the hydrophilic compound and the reaction between the polyisocyanate and the blocking agent can be carried out at the same time, or any reaction can be carried out in advance and then the second and subsequent reactions can be carried out. Among them, the polyisocyanate and the hydrophilic compound are first reacted to obtain a hydrophilic compound-modified polyisocyanate modified with a hydrophilic compound, and then the obtained hydrophilic compound-modified polyisocyanate is reacted with the blocking agent. preferably.

The reaction between the polyisocyanate and the hydrophilic compound may be carried out using an organic metal salt, a tertiary amine compound, or an alkali metal alcoholate as a catalyst. Examples of metals constituting the organic metal salt include tin, zinc, and lead. Examples of the alkali metals include sodium and the like.

The reaction temperature between the polyisocyanate and the hydrophilic compound is preferably −20° C. or higher and 150° C. or lower, more preferably 30° C. or higher and 130° C. or lower. When the reaction temperature is equal to or higher than the above lower limit, the reactivity tends to be higher. Further, when the reaction temperature is equal to or lower than the above upper limit, side reactions tend to be more effectively suppressed.
It is preferable to completely react with the polyisocyanate so that the hydrophilic compound does not remain unreacted. By not remaining in an unreacted state, there is a tendency to more effectively suppress the deterioration of the water dispersion stability of the blocked polyisocyanate composition and the low-temperature curability when formed into a resin film.

The hydrophilic compound-modified polyisocyanate obtained by the above reaction, the imidazole-based blocking agent (b1), and the blocking agent (b2) other than b1 can be reacted at the same time. Eye reactions can also be performed.
Among them, in order to prevent the imidazole-based blocking agent (b1) from remaining in an unreacted state, it is preferable to first react the imidazole-based blocking agent (b1) and then react the blocking agent (b2) other than b1. .

The amount of the blocking agent added is usually 80 mol% or more and 200 mol% or less, and may be 90 mol% or more and 150 mol% or less with respect to the total molar amount of isocyanate groups in the polyisocyanate after modifying the hydrophilic group compound. is preferred.
Moreover, when using a solvent, a solvent inert to an isocyanate group may be used.

When a solvent is used, the content of nonvolatile matter derived from the polyisocyanate and the blocking agent relative to 100 parts by mass of the blocked polyisocyanate composition may usually be 10 parts by mass or more and 95 parts by mass or less, and may be 20 parts by mass or more and 80 parts by mass. It is preferably no more than 30 parts by mass and more preferably 30 parts by mass or more and 75 parts by mass or less.

In the blocking reaction, organometallic salts such as tin, zinc and lead, tertiary amine compounds, alcoholates of alkali metals such as sodium, and the like may be used as catalysts.

The amount of the catalyst to be added varies depending on the temperature of the blocking reaction and the like. It is preferable that it is more than 1.0 mass part or less.

The blocking reaction can generally be carried out at -20°C or higher and 120°C or lower, preferably at 0°C or higher and 100°C or lower, more preferably at 10°C or higher and 80°C or lower, and 30°C or higher and 70°C or lower. is even more preferred. When the temperature of the blocking reaction is equal to or higher than the above lower limit, the reaction rate can be further increased, and when it is equal to or lower than the above upper limit, side reactions can be further suppressed.

After the blocking reaction, a neutralization treatment may be performed by adding an acidic compound or the like.

As said acidic compound, an inorganic acid may be used and an organic acid may be used. Examples of inorganic acids include hydrochloric acid, phosphorous acid, and phosphoric acid. Examples of organic acids include methanesulfonic acid, p-toluenesulfonic acid, dioctyl phthalate, dibutyl phthalate and the like.

In the blocking reaction, organometallic salts such as tin, zinc and lead, tertiary amine compounds, alcoholates of alkali metals such as sodium, and the like may be used as catalysts.

<Other components>
The blocked polyisocyanate composition of the present embodiment can further contain additives such as solvents in addition to the blocked polyisocyanate component.

Examples of solvents include 1-methylpyrrolidone, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy-3-methyl- 1-butanol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether (DPDM), propylene glycol dimethyl ether, methyl ethyl ketone, acetone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, ethanol, methanol, iso-propanol, 1-propanol, iso-butanol, 1-butanol, tert-butanol, 2-ethylhexanol, cyclohexanol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol , 1,3-butanediol, ethyl acetate, isopropyl acetate, butyl acetate, toluene, xylene, pentane, iso-pentane, hexane, iso-hexane, cyclohexane, solvent naphtha, mineral spirits and the like. These solvents may be used singly or in combination of two or more. From the viewpoint of dispersibility in water, the solvent preferably has a solubility in water of 5% by mass or more, and specifically, DPDM is preferred.

(Average number of isocyanate groups of blocked polyisocyanate composition)
The average number of isocyanate groups of the blocked polyisocyanate composition used in the present embodiment is preferably 2.0 or more from the viewpoint of improving the low-temperature curability of the resin film, and the low-temperature curability of the resin film and , From the viewpoint of compatibility with the polyhydroxy compound, it is more preferably 2.4 or more and 20.0 or less, more preferably 2.6 or more and 10.0 or less, and particularly preferably 2.7 or more and 8.0 or less. , 3.0 or more and 6.0 or less.
The average number of isocyanate functional groups of the blocked polyisocyanate composition can be measured using the method described in the examples below.

(Effective NCO content of blocked polyisocyanate composition)
The effective NCO content of the blocked polyisocyanate composition used in the present embodiment is the solid content (non-volatile content) from the viewpoint of compatibility with water resistance and polyvalent hydroxy compounds when it is made into a resin film. The value of 70% by mass is preferably 3% by mass or more and 15.0% by mass or less, more preferably 3.5% by mass or more and 13.0% by mass or less, and further 4.0% by mass or more and 11.5% by mass or less. It is preferably 5.0% by mass or more and 10.0% by mass or less is particularly preferable.
The effective NCO content of the blocked polyisocyanate composition can be measured using the method described in Examples below.

<Method for producing blocked polyisocyanate composition>
The blocked polyisocyanate composition of the present embodiment is obtained by mixing a blocked polyisocyanate component and, if necessary, other components such as a solvent.
Alternatively, a block polyisocyanate composition may be produced by mixing a block polyisocyanate component and, if necessary, other constituent components such as a solvent, respectively, when formulating a coating material.
Among them, it is preferable to mix the block polyisocyanate component and, if necessary, other components such as a solvent in advance to produce a block polyisocyanate composition.

<<Resin composition>>
The resin composition of this embodiment contains the above-described blocked polyisocyanate composition and a polyhydric hydroxy compound. The resin composition of this embodiment can also be said to be a one-liquid resin composition containing a curing agent component and a main agent component.

By including the blocked polyisocyanate composition, the resin composition of the present embodiment has excellent curability when baked at a low temperature of 90° C. or less immediately after production and after storage immediately after production, and is stored immediately after production. The decrease in pH at the time is suppressed.

Further, the resin composition of the present embodiment is excellent in storage stability when made into a water-based resin composition, and thus is particularly suitably used as a water-based resin composition.

The constituent components of the resin composition of this embodiment will be described in detail below.

<Polyvalent hydroxy compound>
As used herein, the term "polyhydric hydroxy compound" means a compound having at least two hydroxy groups (hydroxyl groups) in one molecule, and is also called a "polyol".
Specific examples of the polyhydric hydroxy compounds include aliphatic hydrocarbon polyols, polyether polyols, polyester polyols, epoxy resins, fluorine-containing polyols, and acrylic polyols.
Among them, polyester polyols, fluorine-containing polyols or acrylic polyols are preferable as the polyhydric hydroxy compound.

[Aliphatic Hydrocarbon Polyols]
Examples of the aliphatic hydrocarbon polyols include hydroxyl-terminated polybutadiene and hydrogenated products thereof.

[Polyether polyols]
Examples of the polyether polyols include those obtained by using any one of the following methods (1) to (3).
(1) Polyether polyols or polytetramethylene glycols obtained by adding alkylene oxides alone or in mixtures to polyhydric alcohols alone or in mixtures.
(2) Polyether polyols obtained by reacting an alkylene oxide with a polyfunctional compound.
(3) So-called polymer polyols obtained by polymerizing acrylamide or the like using the polyether polyols obtained in (1) or (2) as a medium.

Examples of the polyhydric alcohol include glycerol and propylene glycol.
Examples of the alkylene oxide include ethylene oxide and propylene oxide.
Examples of the polyfunctional compound include ethylenediamine and ethanolamines.

[Polyester polyols]
Examples of the polyester polyols include the following polyester polyols (1) or (2).
(1) Polyester polyol resins obtained by a condensation reaction between a dibasic acid alone or a mixture of two or more kinds and a polyhydric alcohol alone or a mixture of two or more kinds.
(2) Polycaprolactones obtained by ring-opening polymerization of ε-caprolactone with a polyhydric alcohol.

Examples of the dibasic acid include carboxylic acids such as succinic acid, adipic acid, dimer acid, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, and 1,4-cyclohexanedicarboxylic acid.
Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, trimethylpentanediol, cyclohexanediol, trimethylolpropane, glycerol, and pentaerythritol. , 2-methylolpropanediol, ethoxylated trimethylolpropane, and the like.

[Epoxy resins]
Examples of the epoxy resins include novolac type epoxy resins, β-methylepichloro type epoxy resins, cyclic oxirane type epoxy resins, glycidyl ether type epoxy resins, glycol ether type epoxy resins, epoxy type aliphatic unsaturated compounds, and epoxidized fatty acids. Epoxy resins such as esters, ester-type polycarboxylic acids, aminoglycidyl-type epoxy resins, halogenated epoxy resins, resorcinol-type epoxy resins, and resins obtained by modifying these epoxy resins with amino compounds, polyamide compounds, etc. be done.

[Fluorinated polyols]
Examples of the fluorine-containing polyols include fluoroolefins, cyclohexyl vinyl ethers, hydroxy Examples thereof include copolymers of alkyl vinyl ethers, monocarboxylic acid vinyl esters, and the like.

[Acrylic polyols]
The acrylic polyols are, for example, polymerizable monomers having one or more active hydrogens in one molecule, or polymerizable monomers having one or more active hydrogens in one molecule, and optionally , obtained by copolymerizing the polymerizable monomer and another copolymerizable monomer.

Examples of the polymerizable monomer having one or more active hydrogens in one molecule include those shown in (i) to (iii) below. These may be used individually by 1 type, and may be used in combination of 2 or more type.
(i) acrylic acid esters having active hydrogen such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and 2-hydroxybutyl acrylate;
(ii) methacrylic acid esters having active hydrogen such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate and 2-hydroxybutyl methacrylate;
(iii) (meth)acrylic acid esters having polyvalent active hydrogen, such as glycerol monoester acrylate or methacrylate, trimethylolpropane monoester acrylate or methacrylate;

Other monomers copolymerizable with the polymerizable monomer include, for example, the following (i) to (v). These may be used individually by 1 type, and may be used in combination of 2 or more type.
(i) acrylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate and 2-ethylhexyl acrylate;
(ii) methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, lauryl methacrylate, and glycidyl methacrylate .
(iii) unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid;
(iv) unsaturated amides such as acrylamide, N-methylol acrylamide, diacetone acrylamide;
(v) styrene, vinyl toluene, vinyl acetate, acrylonitrile, and the like;

In addition, acrylic polyols obtained by copolymerizing polymerizable UV-stable monomers disclosed in Reference Document 4 (JP-A-1-261409) and Reference Document 5 (JP-A-3-006273), etc. and the like.

Specific examples of the polymerizable UV-stable monomer include 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6 ,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 2-hydroxy-4-(3-methacryloxy-2-hydroxypropoxy)benzophenone and the like. be done.

For example, the above monomer components are 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 obtaining a water-based base acrylic polyol, it can be produced by a known method such as solution polymerization of an olefinic unsaturated compound and conversion to an aqueous layer, or emulsion polymerization. In that case, water-solubility or water-dispersibility can be imparted by neutralizing acidic moieties such as carboxylic acid-containing monomers such as acrylic acid and methacrylic acid and sulfonic acid-containing monomers with amines or ammonia.

[Hydroxyl value and acid value of polyhydric hydroxy compound]
The hydroxyl value of the polyhydric hydroxy compound contained in the resin composition of the present embodiment is preferably 5 mgKOH/g or more and 300 mgKOH/g or less, more preferably 10 mgKOH/g or more and 280 mgKOH/g or less, and 30 mgKOH/g. more preferably 250 mgKOH/g or less. When the hydroxyl value of the polyhydric hydroxy compound is within the above range, it is possible to obtain a resin film that is more excellent in various physical properties such as tensile strength. Specifically, when the number of hydroxyl groups in the polyhydroxy compound is at least the above lower limit, the crosslink density of urethane due to the reaction with polyisocyanate is further increased, and the function of urethane bonds is more likely to be exhibited. On the other hand, when the number of hydroxyl groups in the polyhydric hydroxy compound is not more than the above upper limit, the crosslink density does not increase excessively and the mechanical properties of the resin film become better. The hydroxyl value of the polyvalent hydroxy compound is measured, for example, by potentiometric titration, and calculated as a value relative to the solid content in the polyvalent hydroxy compound.

[Glass transition temperature Tg of polyhydric hydroxy compound]
The glass transition temperature Tg of the polyhydroxy compound contained in the resin composition of the present embodiment is preferably 0°C or higher and 100°C or lower, more preferably 0°C or higher and 90°C or lower, and 0°C or higher and 80°C. It is more preferably 5° C. or higher and 70° C. or lower, particularly preferably 5° C. or higher and 70° C. or lower. When the glass transition temperature of the polyhydric hydroxy compound is within the above range, a resin film with superior tensile strength can be obtained. The glass transition temperature of the polyhydric hydroxy compound can be measured using, for example, a differential scanning calorimeter (DSC) measuring device.

[Weight average molecular weight Mw of polyhydroxy compound]
The weight average molecular weight Mw of the polyhydric hydroxy compound is preferably 5.0×10 ³ or more and 2.0×10 ⁵ or less, more preferably 5.0×10 ³ or more and 1.5×10 ⁵ or less. It is more preferably 5.0×10 ³ or more and 1.0×10 ⁵ or less. When the weight average molecular weight Mw of the polyhydric hydroxy compound is within the above range, it is possible to obtain a resin film that is more excellent in various physical properties such as tensile strength. The weight average molecular weight Mw of the polyhydric hydroxy compound is the polystyrene-based weight average molecular weight measured by gel permeation chromatography (GPC).

[NCO/OH]
The molar equivalent ratio (NCO/OH) of the isocyanate groups of the blocked polyisocyanate composition to the hydroxyl groups of the polyhydric hydroxy compound contained in the resin composition of the present embodiment is determined according to the required physical properties of the resin film, but is usually , 0.01 to 10.0, preferably 0.1 to 5.0, more preferably 0.2 to 3.0, even more preferably 0.25 to 2.0.

[Content of blocked polyisocyanate composition]
In the resin composition of the present embodiment, the content of the blocked polyisocyanate may be any amount as long as the molar equivalent ratio of the isocyanate groups of the blocked polyisocyanate to the hydroxyl groups of the polyhydroxy compound is within the above range. It is preferably 1 part by mass or more and 200 parts by mass or less, more preferably 5 parts by mass or more and 180 parts by mass or less, and even more preferably 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the hydroxy compound. When the content of the blocked polyisocyanate is within the above range, a resin film having excellent properties such as tensile strength can be obtained. The content of the blocked polyisocyanate can be calculated, for example, from the compounded amount, or identified and quantified using nuclear magnetic resonance (NMR) method and gas chromatography/mass spectrometry (GC/MS method). can also be calculated by

<Other additives>
The resin composition of this embodiment may further contain other additives.
Other additives include, for example, curing agents that can react with crosslinkable functional groups in polyhydroxy compounds, curing catalysts, solvents, pigments (extender pigments, coloring pigments, metallic pigments, etc.), UV absorbers, light stabilizers. agents, radical stabilizers, anti-yellowing agents for suppressing coloration during the baking process, coating surface modifiers, fluidity modifiers, pigment dispersants, antifoaming agents, thickeners, film-forming aids, and the like.

Examples of the curing agent include melamine resins, urea resins, epoxy group-containing compounds or resins, carboxyl group-containing compounds or resins, acid anhydrides, alkoxysilane group-containing compounds or resins, and hydrazide compounds.

The curing catalyst may be a basic compound or a Lewis acidic compound.
Examples of the basic compound include metal hydroxides, metal alkoxides, metal carboxylates, metal acetylacetinates, hydroxides of onium salts, onium carboxylates, halides of onium salts, metal salts of active methylene compounds, Examples include onium salts of active methylene compounds, aminosilanes, amines, phosphines, and the like. As the onium salt, an ammonium salt, a phosphonium salt or a sulfonium salt is suitable.
Examples of the Lewis acidic compound include organic tin compounds, organic zinc compounds, organic titanium compounds, organic zirconium compounds, and the like.

Examples of the solvent include those exemplified for the block polyisocyanate composition.

In addition, pigments (extender pigments, color pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, coating surface conditioners, flow control agents, pigments As the dispersant, antifoaming agent, thickener and film-forming aid, known ones can be appropriately selected and used.

<Method for producing resin composition>
The resin composition of the present embodiment can be used both as a solvent-based resin composition and as a water-based resin composition, but is preferably used as a water-based resin composition.
At this time, in the block polyisocyanate composition, other constituents such as a solvent may be added to the polyhydric hydroxy compound, which is the main ingredient, if necessary.
Above all, it is preferable to add a block polyisocyanate composition and, if necessary, a mixture of other components such as a solvent in advance to the polyvalent hydroxy compound as the main ingredient.

When producing an aqueous-based resin composition (aqueous resin composition), first, a polyvalent hydroxy compound or an aqueous dispersion or water solution thereof is added, if necessary, to a crosslinkable functional group in the polyvalent hydroxy compound. curing agents, curing catalysts, solvents, pigments (extender pigments, colored pigments, metallic pigments, etc.), ultraviolet absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, Additives such as coating surface modifiers, fluidity modifiers, pigment dispersants, antifoaming agents, thickeners and film forming aids are added. Next, the block polyisocyanate composition or its aqueous dispersion is added as a curing agent, and if necessary, water or a solvent is further added to adjust the viscosity. Then, a water-based resin composition (water-based resin composition) can be obtained by forcibly stirring with a stirring device.

When producing a solvent-based resin composition, first, a polyvalent hydroxy compound or a solvent-diluted product thereof is added, if necessary, with a curing agent capable of reacting with a crosslinkable functional group in the polyvalent hydroxy compound, and a curing catalyst. , Solvents, Pigments (extender pigments, colored pigments, metallic pigments, etc.), UV absorbers, light stabilizers, radical stabilizers, anti-yellowing agents that suppress coloring during the baking process, coating surface modifiers, flow modifiers, Additives such as a pigment dispersant, an antifoaming agent, a thickener, and a film forming aid are added. Next, the block polyisocyanate composition is added as a curing agent, and if necessary, a solvent is further added to adjust the viscosity. A solvent-based resin composition can then be obtained by stirring by hand or by using a stirring device such as a mazeler.

≪Resin film≫
The resin film of this embodiment is obtained by curing the resin composition. The resin film of this embodiment is excellent in water resistance.

The resin film of the present embodiment is obtained by coating the resin composition on a base material using a known method such as roll coating, curtain flow coating, spray coating, bell coating, electrostatic coating, and curing by heating. obtained by

The heating temperature is preferably about 70° C. or higher and about 120° C. or lower, more preferably about 70° C. or higher and about 110° C. or lower, and even more preferably about 75° C. or higher and about 100° C. or lower, from the viewpoint of energy saving and heat resistance of the substrate.
The heating time is preferably from about 1 minute to about 60 minutes, more preferably from about 2 minutes to about 40 minutes, from the viewpoint of energy saving and heat resistance of the substrate.

The base material is not particularly limited. For example, the outer panel of automobile bodies such as passenger cars, trucks, motorcycles, and buses; automobile parts such as bumpers; the outer panels of home appliances such as mobile phones and audio equipment. Part: Various films can be mentioned, and among them, an outer plate part of an automobile body or an automobile part is preferable.

The material of the substrate is not particularly limited, and examples include iron, aluminum, brass, copper, tinplate, stainless steel, galvanized steel, and zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.) plating. Metal materials such as steel; resins such as polyethylene resin, polypropylene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin, various FRPs, etc. plastic materials; inorganic materials such as glass, cement and concrete; wood; fibrous materials such as paper and cloth;

The base material is the surface of the metal material, or the surface of a metal body such as a car body molded from the metal material, which is subjected to surface treatment such as phosphate treatment, chromate treatment, and composite oxide treatment. It may also be one on which a coating film is formed. The base material on which the paint film is formed may be a substrate that has been subjected to surface treatment as necessary and has an undercoat film formed thereon, such as a vehicle body on which the undercoat film is formed with an electrodeposition paint. good. The base material may be the surface of the plastic material, or the surface of the plastic such as automobile parts molded from the metal material, which is subjected to a desired surface treatment. Also, the substrate may be a combination of a plastic material and a metal material.

Since the resin film of the present embodiment is excellent in low-temperature curability, it can be suitably used as a coating film for materials with low heat resistance and products in various fields where energy saving is required.

≪Laminate≫
The laminate of the present embodiment is obtained by laminating one or more layers of the resin film on a substrate.
The thickness of one layer of the resin film is 1 μm or more and 50 μm or less.

The laminate of the present embodiment may include two or more layers of the resin films having the same composition, or may include two or more layers of the resin films having different compositions.

Further, examples of the base material include those exemplified in the above "resin film".

In the laminate of the present embodiment, the resin composition is coated on a substrate using a known method such as roll coating, curtain flow coating, spray coating, bell coating, and electrostatic coating, and cured by heating. Alternatively, it can be obtained by heating and hardening all the layers together after coating.

In addition to the base material and the resin film, the laminate of the present embodiment can include layers made of other known components such as a primer layer, an adhesive layer, and a decorative layer.

The present embodiment will be described in more detail below based on examples and comparative examples, but the present embodiment is not limited by the following examples.

<Test item>
The polyisocyanates and blocked polyisocyanate components obtained in Synthesis Examples, and the blocked polyisocyanate compositions obtained in Examples and Comparative Examples were measured for their physical properties according to the methods described below, and evaluated. gone.

[Physical properties A]
(Isocyanate group (NCO) content)
In order to measure the NCO content of polyisocyanate, polyisocyanate before blocking with a blocking agent was used as a measurement sample.

First, 2 g or more and 3 g or less of a measurement sample was accurately weighed in a flask (Wg). Then, 20 mL of toluene was added to dissolve the measurement sample. Next, 20 mL of a toluene solution of 2N di-n-butylamine was added, and after mixing, the mixture was allowed to stand at room temperature for 15 minutes. Then 70 mL of isopropyl alcohol was added and mixed. Then, this liquid was titrated with an indicator with a 1N hydrochloric acid solution (Factor F). The obtained titration value was defined as V2 mL. The titration value obtained without the polyisocyanate sample was then taken as V1 ml. Then, the isocyanate group (NCO) content (% by mass) of the polyisocyanate was calculated from the following formula.

Isocyanate group (NCO) content (% by mass) = (V1-V2) x F x 42/(W x 1000) x 100

[Physical properties 2]
(Effective NCO content)
Also, the effective NCO content of the block polyisocyanate composition was calculated by the following formula.

Effective NCO content [mass%]
= {100 x (mass of isocyanate groups in solid content of polyisocyanate used in blocking reaction)}/(mass of blocked polyisocyanate composition after blocking reaction)

[Physical properties B]
(Number average molecular weight and weight average molecular weight)
The number-average molecular weight and weight-average molecular weight are the polystyrene-based number-average molecular weight and weight-average molecular weight measured by gel permeation chromatography (GPC) using the following equipment.
In order to measure the number average molecular weight of polyisocyanate, polyisocyanate before blocking with a blocking agent was used as a measurement sample.
For the number average molecular weight of the blocked polyisocyanate composition and the weight average molecular weight of the polyhydroxy compound, the blocked polyisocyanate composition or the polyhydroxy compound was used as it was as a measurement sample. Measurement conditions are shown below.

(Measurement condition)
Apparatus: HLC-802A manufactured by Tosoh Corporation
Column: G1000HXL x 1, manufactured by Tosoh Corporation
G2000HXL x 1
G3000HXL x 1 Carrier: Tetrahydrofuran Detection method: Differential refractometer

[Physical properties 3]
(Average number of isocyanate groups)
The average number of isocyanate groups (average number of NCOs) of polyisocyanate and blocked polyisocyanate composition was determined by the following formula. In the formula, "Mn" is the number average molecular weight of the polyisocyanate and the blocked polyisocyanate composition, and the value measured in "Physical properties B" above was used for both. "NCO content" is the isocyanate group content of polyisocyanate measured before blocking with a blocking agent, and the value calculated in the above "Physical property A" was used. For the "effective NCO content", the value calculated in [Physical properties 2] was used.

Average number of isocyanate groups of polyisocyanate = (Mn x NCO content x 0.01)/42

Average number of isocyanate groups in blocked polyisocyanate composition = (Mn x effective NCO content x 0.01)/42

[Physical properties 1]
(Blocked polyisocyanate component or non-volatile content of composition)
The nonvolatile content of the blocked polyisocyanate component or composition was determined as follows.
First, an aluminum dish with a bottom diameter of 38 mm was precisely weighed. Next, about 1 g of the blocked polyisocyanate compositions produced in Examples and Comparative Examples were placed on an aluminum dish and weighed accurately (W1). The blocked polyisocyanate composition was then adjusted to a uniform thickness. Next, the blocked polyisocyanate composition placed on an aluminum dish was held in an oven at 105° C. for 1 hour. Then, after the aluminum dish reached room temperature, the blocked polyisocyanate composition remaining in the aluminum dish was precisely weighed (W2). Then, the non-volatile content (% by mass) of the blocked polyisocyanate composition was calculated from the following formula.

Non-volatile content (% by mass) of blocked polyisocyanate composition = W2/W1 x 100

[Preparation of water-based resin composition]
Water-based main acrylic polyol (manufactured by Nuplex, "Setaqua (registered trademark) 6522" (trade name), OH (mass%) (on solids) = 2.4, Acid value (mgKOH/g) = 20, solid content 42 mass %) and each block polyisocyanate composition were blended so that the ratio of the molar amount of isocyanate groups to the molar amount of hydroxyl groups (isocyanate groups/hydroxyl groups) was 1.0. Further, ion-exchanged water was blended and a small amount of triethylamine was added to adjust the pH to about 8.0 or more and 8.5 or less and the solid content to 47% by mass. Then, the solution was stirred at 1000 rpm for 15 minutes using a homodisper to obtain a water-based resin composition after defoaming.

[Evaluation 1]
(pot life)
Immediately after production, the water-based resin composition obtained in the above "preparation of water-based resin composition" was stored at 40°C for 10 days. Before and after storage, the state of the coating liquid was observed and evaluated according to the following evaluation criteria.

(Evaluation criteria)
◯: Gelation, thickening, and sedimentation are not observed.
Δ: Increased viscosity and partial sedimentation were observed.
x: The coating liquid gelled within 10 days at 40°C.

[Evaluation 2]
(dispersibility)
The resin composition obtained in the above "preparation of water-based resin composition" was coated on a glass plate immediately after production so that the dry film thickness was 40 μm, and then dried by heating at 85° C. for 30 minutes to obtain a resin film.
The appearance of the resulting coating film was observed and judged according to the following evaluation criteria.

(Evaluation criteria)
◯: White turbidity of the coating film cannot be seen △: Overall white turbidity of the coating film ×: Cracks and cissing are observed.

[Evaluation 3]
(low temperature curing)
Immediately after the resin composition obtained in the above "Preparation of water-based resin composition" was coated on a polypropylene (PP) plate so that the dry film thickness was 40 μm, the resin film was dried by heating at 85° C. for 30 minutes. Obtained. The percentage (% by mass) of the value obtained by dividing the undissolved portion mass when the obtained resin film was immersed in acetone at 23° C. for 24 hours by the mass before immersion was obtained as the gel fraction. Using the calculated gel fraction, low-temperature curability was evaluated according to the following evaluation criteria.

(Evaluation criteria)
◎: Gel fraction is 90% by mass or more ○: Gel fraction is 85% by mass or more and less than 90% △: Gel fraction is 80% by mass or more and less than 85% ×: Gel fraction is less than 80% by mass

[Evaluation 4]
(water resistant)
The resin composition obtained in the above "preparation of water-based resin composition" was coated on a glass plate immediately after production so that the dry film thickness was 40 μm, and then dried by heating at 85° C. for 30 minutes to obtain a resin film.
The obtained coating film was immersed in deionized water at 30° C. for 24 hours, and the surface of the coating film after taking it out was lightly wiped off with a kimtowel.

(Evaluation criteria)
A: No difference between the immersed portion and the non-immersed portion.
◯: A small lump is seen in a part of the immersion part.
Δ: Blisters are observed in the entire immersion portion.
x: Swelling and partial peeling of the coating film are observed.

<Synthesis of polyisocyanate>
[Synthesis Example 1]
(Synthesis of polyisocyanate P-1)
A four-necked flask equipped with a thermometer, a stirring blade and a reflux condenser was charged with 100 parts by mass of HDI under a nitrogen stream, and the temperature inside the reactor was maintained at 60°C under stirring to produce trimethylbenzylammonium hydroxide. 0.095 parts by mass was added, and after 4.5 hours, when the conversion reached 40% by mass, 0.02 parts by mass of phosphoric acid was added to terminate the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P-1"). The obtained polyisocyanate P-1 had an NCO content of 22.0% by mass, a number average molecular weight of 655, and an average number of isocyanate groups of 3.4. Further, the obtained polyisocyanate P-1 was subjected to ¹ H-NMR analysis to confirm the presence of isocyanurate groups.

[Synthesis Example 2]
(Synthesis of polyisocyanate P-2)
In a four-necked flask equipped with a thermometer, a stirring blade and a reflux condenser, 100 parts by mass of HDI and a polyester polyol (polycaprolactone triol) derived from a trihydric alcohol and ε-caprolactone are placed under a nitrogen stream. ("PLAXEL 303" (trade name) manufactured by Daicel Chemical Industries, average number of functional groups: 3, number average molecular weight: 300): 5.3 parts by mass were charged, and the temperature in the reactor was maintained at 89°C for 1 hour while stirring. reaction was carried out. After that, the temperature inside the reactor was kept at 63° C., an isocyanurate-forming catalyst, tetramethylammonium capriate, was added, and when the yield reached 52% by mass, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed using a thin film evaporator to obtain an isocyanurate-type polyisocyanate (hereinafter sometimes referred to as "polyisocyanate P-2").
The resulting polyisocyanate P-2 had an NCO content of 18.6% by mass, a number average molecular weight of 1220, and an average number of isocyanate groups of 5.4. Further, the polyisocyanate P-2 thus obtained was subjected to ¹ H-NMR analysis to confirm the presence of isocyanurate groups.

<Production of blocked polyisocyanate composition (A)>
[Example 1]
(Production of blocked polyisocyanate composition A-1)
In a four-necked flask equipped with a thermometer, stirring blades and a reflux condenser, polyisocyanate P-1 obtained in Synthesis Example 1: 100 parts by mass and 2-ethylhexyl acid phosphate (Johoku Kagaku Kogyo Co., Ltd.) are added under a nitrogen stream. Company, "JP-508T" (trade name)): 0.01 parts by mass, and methoxypolyethylene glycol (M400, number average molecular weight: 400, manufactured by NOF Corporation): 25.1 parts by mass (polyisocyanate P 12 mol % with respect to 100 mol % of the isocyanate group of -1) was mixed and reacted at 120° C. for 3 hours. The reaction solution was cooled to 60° C., and 72.6 parts of dipropylene glycol dimethyl ether (DPDM) and 2-ethylimidazole were charged so as to be 70 mol % with respect to 100 mol % of the isocyanate groups of polyisocyanate P-1, The external bath was adjusted so that the solution temperature was 60° C., and the blocking reaction was carried out at 60° C. for 90 minutes. After that, 3,5-dimethylpyrazole was charged so as to be 18 mol% with respect to 100 mol% of the isocyanate groups of polyisocyanate P-1, and the external bath was adjusted so that the solution temperature was 60°C, and further 60°C. for 60 minutes. The disappearance of the isocyanate group peak was confirmed by infrared spectroscopy (IR) to obtain a blocked polyisocyanate composition A-1. Using the block polyisocyanate composition thus obtained, physical properties 1 to 3 were calculated and evaluations 1 to 4 were performed, and the results are shown in Table 2.

[Examples 2 to 12, Comparative Examples 1 to 4]
(Production of blocked polyisocyanate compositions A-2 to A-12 and B-1 to B-4)
Block polyisocyanate compositions A-2 to A-12 and B-1 to B-4 were obtained in the same manner as in Example 1 except for the items listed in Table 1. Using the obtained blocked polyisocyanate compositions A-2 to A-12 and B-1 to B-4, physical properties 1 to 3 were calculated and evaluations 1 to 4 were performed, and the results are shown in Table 2. .

Hydrophilic compound M400: methoxypolyethylene glycol (number average molecular weight: 400, manufactured by NOF Corporation)
・ MPG081: methoxy polyethylene glycol (number average molecular weight: 690, manufactured by Nippon Nyukazai Co., Ltd.)
・M1000: Methoxy polyethylene glycol (number average molecular weight: 1,000, manufactured by NOF Corporation)

Blocking agent (b1)
・2EZ: 2-ethylimidazole ・4MZ: 4-methylimidazole

Blocking agent (b2)
・3,5DMP: 3,5-dimethylpyrazole ・MEKOx: methyl ethyl ketoxime

Solvent/DPDM: Dipropylene glycol dimethyl ether

According to the blocked polyisocyanate composition of the present embodiment, it has excellent dispersibility when made into a water-based resin composition, has excellent pot life of the paint, and has excellent curability when baked at a low temperature of 90 ° C. or less, It is possible to provide a blocked polyisocyanate composition which is excellent in water resistance when used as a coating film. A water-based resin composition containing the above-mentioned blocked polyisocyanate composition is excellent in low-temperature curability, and thus is suitable for coating materials with low heat resistance.

Claims (6)

A polyisocyanate compound obtained from an aliphatic isocyanate and/or an alicyclic isocyanate, a hydrophilic compound, an imidazole-based blocking agent (b1) having a structure represented by the following general formula (I), and a blocking agent (b2) other than b1 a blocked polyisocyanate derived from
The ratio of the active hydrogen groups of the hydrophilic compound to 100 mol of the isocyanate groups of the polyisocyanate compound is 1 mol or more and 30 mol or less,
A blocked polyisocyanate composition in which the molar ratio (b1/b2) of b1 and b2 is from 95/5 to 5/95.

(In general formula (I), R ¹¹ , R ¹² and R ¹³ are each independently a hydrogen atom or an alkyl optionally containing one or more substituents selected from the group consisting of a hydroxy group and an amino group. The total number of carbon atoms of R ¹¹ , R ¹² and R ¹³ is 1 or more and 20 or less.) 2. The block polyisocyanate composition according to claim 1, wherein said hydrophilic compound is a polyoxyethylene compound having a number average molecular weight of 200 or more and 2000 or less. 3. The blocked polyisocyanate composition according to claim 1, wherein the blocking agent (b2) other than b1 is a pyrazole compound or an oxime compound. A resin composition comprising the blocked polyisocyanate composition according to any one of claims 1 to 3 and a polyhydric hydroxy compound. A resin film obtained by curing the resin composition according to claim 4 . A laminate obtained by laminating one or more layers of the resin film according to claim 5 on a substrate,
A layered product, wherein the resin film has a thickness of 1 μm or more and 50 μm or less per layer.