JP2022178395A - Encapsulated blocked polyisocyanate and use thereof - Google Patents

Abstract

To provide an encapsulated blocked polyisocyanate that can give a coating composition having high storage stability, and can also give a coating film having excellent low-temperature curability and excoriation resistance.SOLUTION: An encapsulated blocked polyisocyanate is composed of a blocked polyisocyanate coated with at least one crosslinked coating film selected from a group consisting of a polyurea film, a polyurethane film, and an acryl copolymer film.SELECTED DRAWING: None

Description

The present invention relates to encapsulated blocked polyisocyanates and their uses. Specifically, the present invention relates to encapsulated blocked polyisocyanates, aqueous dispersions of encapsulated blocked polyisocyanates, solvent-based one-component coating compositions, water-based one-component coating compositions, coatings and coated articles.

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, by heating, the blocking agent is dissociated, the active isocyanate group is regenerated, and reacts with the polyol to cause a cross-linking reaction, which can solve the above problems. Therefore, many blocking agents have been studied, and representative blocking agents include phenol and methyl ethyl ketoxime.

However, when blocked polyisocyanates containing these blocking agents are used, baking temperatures as high as 140° C. or higher are 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.
Further, for example, Patent Document 3 proposes, as a dissociation-type blocked polyisocyanate, a water-dispersible blocked polyisocyanate using an imidazole compound as a blocking agent.

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

However, when the blocked polyisocyanate compositions described in Patent Documents 1 to 3 and the like are used, although curing progresses at a low temperature of about 100° C., the storage stability may be insufficient.

The present invention has been made in view of the above circumstances, and provides an encapsulated block polyisocyanate that provides a coating composition with excellent storage stability and a coating film that is excellent in low-temperature curability and scratch resistance. offer. Also provided are an aqueous dispersion of an encapsulated block polyisocyanate, a solvent-based one-component coating composition, a water-based one-component coating composition, a coating film, and a coated article using the encapsulated block polyisocyanate.

That is, the present invention includes the following aspects.
(1) An encapsulated block polyisocyanate comprising a block polyisocyanate coated with one or more cross-linked coating films selected from the group consisting of polyurea films, polyurethane films, and acrylic copolymer films.
(2) The encapsulated block polyisocyanate according to (1), wherein the crosslinked coating film is a polyurea film.
(3) An aqueous dispersion of encapsulated block polyisocyanate, which is obtained by dispersing the encapsulated block polyisocyanate according to (1) or (2) in water.
(4) the encapsulated block polyisocyanate according to (1) or (2);
a polyvalent active hydrogen compound;
A solvent-based one-part coating composition containing
(5) an aqueous dispersion of the encapsulated block polyisocyanate according to (3);
a polyvalent active hydrogen compound;
A water-based one-liquid coating composition containing
(6) A coating film obtained by curing the solvent-based one-component coating composition according to (4).
(7) A coating film obtained by curing the water-based one-component coating composition according to (5).
(8) A coated article comprising the coating film according to (6) or (7).

According to the encapsulated block polyisocyanate of the above-described aspect, it is possible to provide an encapsulated block polyisocyanate capable of obtaining a coating composition having excellent storage stability and a coating film having excellent low-temperature curability and scratch resistance. can.

EMBODIMENT OF THE INVENTION Hereinafter, the form (only henceforth "this embodiment") for implementing this invention is demonstrated in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be appropriately modified and implemented within the scope of the gist thereof.

As used herein, "polyol" means a compound having two or more hydroxy groups (--OH).
As used herein, the term “polyisocyanate” means a reactant in which a plurality of monomeric compounds (hereinafter abbreviated as “isocyanate monomers”) having one or more isocyanate groups (—NCO) are bonded.

≪Encapsulated block polyisocyanate≫
The encapsulated block polyisocyanate of this embodiment consists of a block polyisocyanate coated with one or more cross-linked coating films selected from the group consisting of polyurea films, polyurethane films, and acrylic copolymer films. In other words, the encapsulated blocked polyisocyanate of the present embodiment is a polymer particle having a core-shell structure in which the core layer is the blocked polyisocyanate and the shell layer is the crosslinked coating film.

The encapsulated blocked polyisocyanate of the present embodiment is a block polyisocyanate exhibiting low-temperature curability that is coated with the above-described crosslinked coating film. Dissociation of the blocking agent can be suppressed, and good storage stability can be maintained. On the other hand, when the coating composition containing the encapsulated blocked polyisocyanate of the present embodiment is used to form a coating film, the shell layer is cleaved or swelled by heat, thereby releasing the blocked polyisocyanate into the coating liquid. By doing so, the curability at a low temperature of about 60° C. or higher and 120° C. or lower (hereinafter also referred to as “low temperature curability”) can be improved. Furthermore, the obtained coating film can exhibit excellent scratch resistance, probably due to the presence of the crosslinked coating film derived from the shell layer of the encapsulated block polyisocyanate in the cured coating film.

The constituent components of the encapsulated block polyisocyanate of this embodiment are described in detail below.

<Crosslinked coating film>
The crosslinked coating film is one or more crosslinked films selected from the group consisting of polyurea films, polyurethane films, and acrylic copolymer films.

[Polyurea film]
Polyurea films are derived from polyamine compounds and polyisocyanates, ie, the reaction product of polyamine compounds and polyisocyanates.

(Polyamine compound)
The polyamine compound is not particularly limited, but has one or more primary amino groups or secondary amino groups per molecule and two or more functional groups that can react with isocyanate groups per molecule. is.

That is, polyamine compounds include polyamines having only primary or secondary amino groups, and alkanolamines having primary or secondary amino groups and hydroxyl groups.

Specific examples of polyamines include those shown in (1) to (3) below.
(1) Diamines such as ethylenediamine, propylenediamine, butylenediamine, triethylenediamine, hexamethylenediamine, 4,4′-diaminodicyclohexylmethane, piperazine, 2-methylpiperazine, and isophoronediamine;
(2) Chain polyamines having three or more amino groups, such as bishexamethylenetriamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentamethylenehexamine, and tetrapropylenepentamine;
(3) 1,4,7,10,13,16-hexaazacyclooctadecane, 1,4,7,10-tetraazacyclodecane, 1,4,8,12-tetraazacyclopentadecane, 1,4, Cyclic polyamines such as 8,11-tetraazacyclotetradecane.

Specific examples of alkanolamine include monoethanolamine, diethanolamine, aminoethylethanolamine, N-(2-hydroxypropyl)ethylenediamine, mono-, di-(n- or iso-)propanolamine, ethylene glycol-bis - propylamine, neopentanolamine, methylethanolamine, and the like.

Among them, as the polyamine compound, a polyamine having only a primary amino group or a secondary amino group is preferable. is more preferred, and polyamines having two secondary amino groups per molecule are more preferred.

Examples of polyamines having two or more secondary amino groups in one molecule include compounds represented by the following general formula (I) (hereinafter sometimes referred to as "compound (I)").

In the general formula (I), ^X11 is an n-valent organic group obtained by removing a primary amino group of an n11-valent polyamine. R ¹¹ and R ¹² are the same or different organic groups which are inert towards isocyanate groups under the reaction conditions. n11 is an integer of 2 or more.

X ¹¹ in formula (I) is not particularly limited, but from the viewpoint of yellowing resistance, it is preferably an organic group based on an aliphatic and/or alicyclic polyamine having no aromatic group. n11-valent polyamine selected from the following group: ethylenediamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 2,5-diamino-2,5- dimethylhexane, 2,2,4- and/or 2,4,4-trimethyl-1,6-diaminohexane, 1,11-diaminoundecane, 1,12-diaminododecane, 1-amino-3,3,5 -trimethyl-5-aminomethylcyclohexane, 2,4- and/or 2,6-hexahydrotolylenediamine, 2,4'- and/or 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl- 4,4'-diaminodicyclohexylmethane, 2,4,4'-triamino-5-methyldicyclohexylmethane, and poly(poly) having a number average molecular weight of 148 or more and 6000 or less, in which primary amino groups are aliphatically bonded It is an organic group based on ether polyamines and the like.
Among them, X ¹¹ is 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 2,2,4- and/or 2,4,4-trimethyl-1,6-diamino organic groups based on hexane, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane, 4,4'-diaminodicyclohexylmethane, or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane; Preferably. More preferably, it is an organic group based on 4,4'-diaminodicyclohexylmethane or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

“Inactive to isocyanate groups under reaction conditions” defined for R ¹¹ and R ¹² in formula (I) means that these groups are Zerewitinoff-active hydrogens such as hydroxyl, amino, or thiol groups. It means having no containing group (CH acidic compound).
R ¹¹ and R ¹² are each independently preferably an alkyl group having 1 to 10 carbon atoms, more preferably a methyl group, an ethyl group, or a butyl group.

n11 in formula (I) is preferably an integer of 2 or more and 6 or less, more preferably an integer of 2 or more and 4 or less, and still more preferably 2.

Preferred compounds (I) include, for example, aspartic acid ester compounds derived from two molecules of aspartic acid having a secondary amino group and one molecule of 4,4'-diaminodicyclohexylmethane.

Although the method for producing compound (I) is not particularly limited, for example, by reacting a primary polyamine represented by the following formula (II) with a maleic acid ester or fumaric acid ester represented by the following formula (III) manufactured.

X ¹¹ -[NH ₂ ] _n11 (II)
R ¹¹ OOC-CH=CH-COOR ¹² (III)

(In the above formula, X ¹¹ , R ¹¹ , R ¹² and n11 have the same meanings as those represented by formula (I).)

Suitable polyamines include, but are not limited to, the diamines mentioned above as the basis for ^X11 .

^Suitable maleic acid ^esters or fumaric acid esters ^are not particularly limited ^. is an ester. Among them, maleic acid esters or fumaric acid esters in which R ¹¹ and R ¹² are alkyl groups having 1 to 10 carbon atoms are preferred, such as dimethyl maleate, diethyl maleate, dibutyl maleate, dimethyl fumarate, diethyl fumarate, or Dibutyl fumarate is more preferred.

The preparation of the aspartate compounds from the starting materials described is preferably carried out in the temperature range from 0°C to 100°C. The starting materials are used in proportions such that in each primary amino group there is at least one, preferably only one, olefinic double bond. If desired, excess starting materials can be removed by distillation after the reaction. The reaction can be carried out in bulk or in the presence of a suitable solvent such as, but not limited to, methanol, ethanol, propanol or dioxane, or mixtures of such solvents.

(polyisocyanate)
A polyisocyanate is a reactant obtained by reacting multiple isocyanate monomers.
As the isocyanate monomer, those having 4 to 30 carbon atoms are preferable. Specific examples of the isocyanate monomer include the following. These isocyanate monomers may be used singly or in combination of two or more.
(1) Diphenylmethane-4,4'-diisocyanate (hereinafter sometimes referred to as "MDI"), 1,5-naphthalene diisocyanate, tolylene diisocyanate (hereinafter sometimes referred to as "TDI"), xylylene diisocyanate , m-tetramethylxylylene diisocyanate (hereinafter sometimes referred to as "TMXDI") and other aromatic diisocyanates;
(2) 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate (hereinafter sometimes referred to as "HDI"), 2,2,4-trimethyl-1,6-diisocyanatohexane, 2, 4,4-trimethyl-1,6-hexamethylene diisocyanate, 2-methylpentane-1,5-diisocyanate (hereinafter sometimes referred to as "MPDI"), lysine diisocyanate (hereinafter referred to as "LDI" There are) aliphatic diisocyanates such as;
(3) 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:
(4) 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 triisocyanates.

Among them, the isocyanate monomer is preferably one or more diisocyanates selected from the group consisting of aliphatic diisocyanates and alicyclic diisocyanates, since the obtained coating film has better weather resistance. Moreover, the isocyanate monomer is more preferably HDI or IPDI from the standpoint of industrial availability.

As the isocyanate monomer, either an aliphatic diisocyanate or an alicyclic diisocyanate may be used alone, or they may be used in combination. Among them, it is preferable to use an aliphatic diisocyanate alone or to use a combination of an aliphatic diisocyanate and an alicyclic diisocyanate, and it is more preferable to use HDI alone or a combination of HDI and IPDI. By using the aliphatic diisocyanate and the alicyclic diisocyanate in combination, the toughness and elasticity of the coating film can be further improved.

In the polyisocyanate, when the aliphatic diisocyanate and the alicyclic diisocyanate are used in combination, the mass ratio of the structural unit derived from the aliphatic diisocyanate to the structural unit derived from the alicyclic diisocyanate is 50/50 or more and 95/ 5 or less is preferable, 60/40 or more and 90/10 or less is more preferable, and 70/30 or more and 80/20 or less is even more preferable.
When the mass ratio of the structural unit derived from the aliphatic diisocyanate to the structural unit derived from the alicyclic diisocyanate 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 the content is equal to or less than the above upper limit, the hardness of the coating film can be further improved.

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

Specific examples of polyisocyanates derived from the above isocyanate monomers include, but are not limited to, the following (1) to (8).
(1) A polyisocyanate compound having a uretdione structure obtained by cyclodimerizing two isocyanate groups.
(2) A polyisocyanate compound having an isocyanurate structure and an iminooxadiazinedione structure obtained by cyclotrimerization of three isocyanate groups.
(3) A polyisocyanate compound having a biuret structure obtained by reacting three isocyanate groups with one water molecule.
(4) A polyisocyanate compound having an oxadiazinetrione structure obtained by reacting two isocyanate groups with one molecule of carbon dioxide.
(5) A polyisocyanate compound having a plurality of urethane groups obtained by reacting one isocyanate group with one hydroxyl group.
(6) A polyisocyanate compound having an allophanate structure obtained by reacting two isocyanate groups with one hydroxyl group.
(7) A polyisocyanate compound having an acyl urea group obtained by reacting one isocyanate group with one carboxyl group.
(8) A polyisocyanate compound having a urea structure obtained by reacting one isocyanate group with one primary or secondary amine.

That is, the polyisocyanate is obtained by reacting a plurality of isocyanate monomers with a compound other than the isocyanate monomer (for example, alcohol, water, amine, etc.) in addition to the polyisocyanate derived from the above isocyanate monomer. It contains polyisocyanates that are reactants that are used.

(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.
Monoalcohols include, for example, methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol and the like.
Examples of dialcohols include ethylene glycol, 1,3-butanediol, neopentyl glycol, and 2-ethylhexanediol.
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 tin alkylcarboxylates (organotin compounds) include tin 2-ethylhexanoate and dibutyltin dilaurate.
Examples of lead alkyl carboxylates (organic lead compounds) include lead 2-ethylhexanoate.
Alkyl carboxylates of zinc (organozinc compounds) include, for example, zinc 2-ethylhexanoate.
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 carried out using an isocyanurate reaction catalyst, which will be described later, an 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-containing 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. It can be manufactured by
The uretdione reaction catalyst is not particularly limited, but examples thereof include tertiary phosphines such as trialkylphosphines, tris(dialkylamino)phosphines, cycloalkylphosphines, 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 obtained. 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) (poly)hydrogen fluoride represented by the general formula M[Fn] or the general formula M[Fn(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 R1-CR'2-C(O)O- or the general formula R2=CR'-C(O)O- and a quaternary ammonium cation or a quaternary A compound consisting of a phosphonium cation.
(In the formula, R1 and R2 are each independently a linear, branched or cyclic saturated or unsaturated perfluoroalkyl group having 1 to 30 carbon atoms. It is selected from the group consisting of a hydrogen atom, and an alkyl group and an aryl group having 1 to 20 carbon atoms which may contain a heteroatom.)

Specific examples of the compound ((poly)hydrogen fluoride) 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, the mass ratio to the mass of the charged isocyanate monomer is preferably 5 ppm, more preferably 10 ppm, and 20 ppm. is more preferred.
The upper limit of the amount of the iminooxadiazine dionization catalyst to be used is preferably 5000 ppm, more preferably 2000 ppm, in terms of mass ratio with respect to the mass of the charged isocyanate monomer, from the viewpoint of suppressing the coloring and discoloration of the product and controlling the reaction. More preferably, 500 ppm is even more preferable.
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 and 500 ppm or less, in terms of mass ratio with respect to the mass of the charged isocyanate monomer. is more preferred.

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 terminated. 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) Tetraalkylammonium hydroxides such as tetramethylammonium, tetraethylammonium and tetrabutylammonium, and the tetraalkylammonium acetates, propionates, octylates, caprates, myristates and benzoic acid Organic weak acid salts such as salts.
(2) Hydroxides of aryltrialkylammonium such as benzyltrimethylammonium and trimethylphenylammonium, and acetates, propionates, octylates, caprates, myristates and benzoates of the aryltrialkylammonium Weak organic acid salts such as
(3) Hydroxyalkylammonium hydroxides such as trimethylhydroxyethylammonium, trimethylhydroxypropylammonium, triethylhydroxyethylammonium and triethylhydroxypropylammonium, and acetates, propionates, octylates, and caprine of the hydroxyalkylammonium weak organic acid salts such as acid salts, myristates and benzoates;
(4) Metal salts of alkylcarboxylic acids such as acetic acid, propionic acid, caproic acid, octylic acid, capric acid and myristic acid, such as tin, zinc and lead.
(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 an organic weak acid salt, and a tetraalkylammonium hydroxide, a tetraalkylammonium hydroxide, or a tetraalkylammonium hydroxide. It is more preferably an organic weak acid salt, an aryltrialkylammonium hydroxide or an aryltrialkylammonium weak organic acid salt.

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 polyisocyanate is preferably 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 55% by mass or less, and 20% by mass or more. It is more preferably 50% by mass or less.
When the conversion rate of the isocyanurate reaction is equal to or less than the above upper limit, the polyisocyanate can be made to have a lower viscosity. 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.

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.

The polymerizable alcohol is not particularly limited, but for example, the average number of hydroxyl groups of the polymerizable alcohol is preferably 3 or more and 8 or less, more preferably 3 or more and 6 or less, further preferably 3 or more and 5 or less, and particularly 3 or 4. preferable.
Specific examples of polymerizable alcohols include polyester polyols, polyether polyols, acrylic polyols, and polyolefin polyols.

A polyester polyol can be obtained, for example, by condensation reaction of 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.
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, glycerin, and pentaerythritol. , 2-methylolpropanediol, ethoxylated trimethylolpropane, and the like.

As a specific method for producing the polyester polyol, for example, the above components are mixed and heated at about 160° C. or higher and 220° C. or lower to carry out a condensation reaction. Alternatively, for example, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone using a polyhydric alcohol can also be used as polyester polyols.
The polyester polyol obtained by the above-described production method should be modified using an aliphatic diisocyanate, an alicyclic diisocyanate, a compound obtained from these, etc., from the viewpoint of the weather resistance and yellowing resistance of the resulting coating film. is preferred.

The polyether polyol can be obtained, for example, using any one of the following methods (1) to (3).
(1) A method of randomly or block-adding an alkylene oxide alone or a mixture to a polyhydric hydroxy compound alone or a mixture using a catalyst to obtain polyether polyols.
Examples of the catalyst include hydroxides of lithium, sodium, potassium, etc., strongly basic catalysts, double metal cyanide complexes, and the like. Examples of strongly basic catalysts include alcoholates and alkylamines. Examples of double metal cyanide complexes include metal porphyrins and zinc hexacyanocobaltate complexes.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide.
(2) A method of reacting a polyamine compound with an alkylene oxide to obtain a polyether polyol.
Examples of the polyamine compound include ethylenediamines.
Examples of the alkylene oxide include those exemplified in (1).
(3) A method of obtaining so-called polymer polyols by polymerizing acrylamide or the like using the polyether polyols obtained in (1) or (2) as a medium.

Examples of the polyvalent hydroxy compound include those shown in (i) to (vi) below.
(i) diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol, etc.;
(ii) sugar alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol, rhamnitol;
(iii) monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose, ribodesose;
(iv) disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, melibiose;
(v) trisaccharides such as raffinose, gentianose, melezitose;
(vi) tetrasaccharides such as stachyose;

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.

Among them, the polymerizable alcohol is preferably a polyester polyol, and more preferably a polycaprolactone polyol obtained by ring-opening polymerization of ε-caprolactone using a low-molecular-weight polyol.

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

Examples of the alcohol include those exemplified in the above "Method for producing isocyanurate group-containing polyisocyanate".

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 the isocyanate groups of the isocyanate monomer to the molar amount of the hydroxyl groups of the alcohol 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 curability will be higher when it is used as a coating composition. improves.

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.

Further, when producing a polyisocyanate derived from an isocyanate monomer and a polymerizable alcohol, for example, the polyisocyanate can be obtained by reacting the isocyanate group of the isocyanate monomer with the hydroxyl group of the polyol.

The molar ratio (NCO/OH) of the isocyanate groups of the diisocyanate to the hydroxyl groups of the polyol is preferably 3/1 or more and 30/1 or less, more preferably 10/1 or more and 20/1 or less. When the NCO/OH ratio is at least the above lower limit value, it is possible to effectively suppress an excessive increase in the viscosity of the polyisocyanate composition to be obtained. On the other hand, when the NCO/OH is equal to or less than the above upper limit, it is possible to effectively suppress the decrease in the productivity of the obtained polyisocyanate composition.

The reaction temperature is preferably 50° C. or higher and 200° C. or lower, more preferably 50° C. or higher and 150° C. or lower. When the reaction temperature is at least the above lower limit, the reaction proceeds more efficiently. can be suppressed. The reaction time is preferably in the range of 0.5 hours or more and 5 hours or less.

After or simultaneously with the reaction between the isocyanate group of the diisocyanate and the hydroxyl group of the polyol, the allophanatization reaction, the uretodionization reaction, the iminooxadiazinedionization reaction, the isocyanurate reaction, the urethanization reaction, and the biuret At least one reaction selected from the group consisting of conversion reactions can be carried out, and among them, the isocyanurate conversion reaction is preferably carried out. By carrying out the isocyanurate-forming reaction, the hardness of the coating film can be further improved.

Polyisocyanate can be obtained by removing the unreacted isocyanate monomer from the reaction solution after completion of the various reactions described above by thin film distillation, extraction, or the like.

(Water-dispersible polyisocyanate)
In addition, since the encapsulated block polyisocyanate of the present embodiment is preferably produced by an interfacial polymerization method in which a polyurea film is formed in water and at the interface of oil droplets, the polyisocyanate exhibits water dispersibility, That is, it is preferably a water-dispersible polyisocyanate. A water-dispersible polyisocyanate is derived from a polyisocyanate and a hydrophilic compound, ie, a reaction product of a polyisocyanate and a hydrophilic compound. The water-dispersible polyisocyanate has a hydrophilic group introduced by forming a bond between at least a portion of the isocyanate group of the polyisocyanate and the functional group of the hydrophilic compound. In other words, at least some isocyanate groups of the polyisocyanate are modified with a hydrophilic compound.

Among the isocyanate groups of the water-dispersible polyisocyanate, the proportion modified with a hydrophilic compound, that is, the modification rate is 0.5 mol% or more and 50 mol% or less with respect to 100 mol% of the isocyanate groups of the raw polyisocyanate. is preferably 1 mol% or more and 30 mol% or less, more preferably 2 mol% or more and 20 mol% or less, and particularly preferably 3 mol% or more and 15 mol% or less. . When the modification rate is equal to or higher than the above lower limit value, it is possible to ensure more sufficient water dispersibility.

1. Hydrophilic compound A hydrophilic compound is a compound having a hydrophilic group. and preferably have one or more. Specific examples of active hydrogen groups include hydroxyl groups, mercapto groups, carboxylic acid groups, amino groups, and thiol groups.

Hydrophilic groups include nonionic hydrophilic groups, cationic hydrophilic groups, and anionic hydrophilic groups. One type of these hydrophilic groups may be used alone, or two or more types may be used in combination. Among them, nonionic hydrophilic groups are preferable as the hydrophilic groups from the viewpoint of availability and resistance to electrical interaction with the formulation.

(1) Hydrophilic compound having a nonionic hydrophilic group As a hydrophilic compound having a nonionic hydrophilic group (hereinafter sometimes referred to as "nonionic hydrophilic compound"), specifically, monoalcohol, alcohol and a compound obtained by adding ethylene oxide to the hydroxyl group of . 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. These nonionic hydrophilic compounds also have active hydrogen groups that react with isocyanate groups.
Among them, as the nonionic hydrophilic compound, a polyalkylene glycol monoalkyl ether obtained by adding an alkylene oxide to the hydroxyl group of a monoalcohol is preferable because it can improve the water dispersibility of the water-dispersible polyisocyanate with a small amount used. Alkyl ethers are more preferred, and polyethylene glycol monomethyl ether is even more preferred.

The number of ethylene oxide additions in the compound to which ethylene oxide is added is preferably 4 or more and 30 or less, more preferably 4 or more and 20 or less. When the number of ethylene oxide additions is at least the above lower limit, there is a tendency to more effectively impart water dispersibility to the water-dispersible polyisocyanate. The water-dispersible polyisocyanate deposit tends to be less likely to occur during low-temperature storage.

The lower limit of the amount of nonionic hydrophilic groups added to the polyisocyanate (hereinafter sometimes referred to as "nonionic hydrophilic group content") is from the viewpoint of the water dispersion stability of the water-dispersible polyisocyanate. , preferably 1% by mass, more preferably 3% by mass, still more preferably 4% by mass, and particularly preferably 4.5% by mass, relative to the mass of the solid content of the water-dispersible polyisocyanate.
Further, the upper limit of the content of the nonionic hydrophilic group is preferably 30% by mass, and 20% by mass based on the mass of the solid content of the water-dispersible polyisocyanate, from the viewpoint of the water resistance of the resulting coating film. More preferably, 10% by mass is even more preferable, and 8% by mass is particularly preferable.
That is, the upper limit of the content of the nonionic hydrophilic group is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less, relative to the mass of the solid content of the water-dispersible polyisocyanate. It is preferably 4% by mass or more and 10% by mass or less, and particularly preferably 4.5% by mass or more and 8% by mass or less.
When the content of the nonionic hydrophilic group is within the above range, the water-dispersible polyisocyanate is more dispersed in water, and the resulting coating film tends to have improved water resistance.

(2) Hydrophilic compound having a cationic hydrophilic group As a hydrophilic compound having a cationic hydrophilic group (hereinafter sometimes referred to as a "cationic hydrophilic compound"), specifically, a cationic hydrophilic and a compound having both a group and an active hydrogen group. Also, 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 preferable 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 polyisocyanate 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 polyisocyanate are preferably neutralized with a compound having an anionic group. Specific examples of this anionic group include a carboxy group, a sulfonic acid group, a phosphoric acid group, a halogen group, a sulfate group, and the like.
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.

(3) Hydrophilic Compound Having Anionic Hydrophilic Group Specific examples of the anionic hydrophilic group include a carboxy group, a sulfonic acid group, a phosphoric acid group, a halogen group, and a sulfate group.

Specific examples of hydrophilic compounds having an anionic hydrophilic group (hereinafter sometimes referred to as "anionic hydrophilic compounds") include compounds having both an anionic group and an active hydrogen group, More specific examples include compounds having a carboxy group of monohydroxycarboxylic acid or polyhydroxycarboxylic acid as an anionic 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 polyisocyanate is preferably neutralized with an amine compound, which is a basic substance.
Specific examples of amine-based 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. In addition, tertiary amines such as triethylamine and dimethylethanolamine can also be used. These amine compounds can be used singly or in combination of two or more.

Moreover, an antioxidant or an ultraviolet absorber may be added to the obtained polyisocyanate, for example, for the purpose of suppressing coloration during storage.
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.

(Method for producing water-dispersible polyisocyanate)
A water-dispersible polyisocyanate is obtained, for example, by reacting a polyisocyanate with a hydrophilic compound.

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 100° 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, the water-dispersible polyisocyanate tends to more effectively suppress deterioration in the water-dispersion stability and the low-temperature curability of the coating composition containing the encapsulated block polyisocyanate of the present embodiment. It is in.

(Physical properties of polyisocyanate)
The isocyanate group content (NCO%) of the polyisocyanate (preferably water-dispersible polyisocyanate) is preferably 5.0% by mass or more and 30.0% by mass or less, and 7.0% by mass or more and 25.0% by mass. It is more preferably not more than 9.0% by mass and even more preferably 9.0% by mass or more and 20.0% by mass or less. When the isocyanate group content (NCO%) is at least the above lower limit, the strength of the polyurea film can be sufficiently maintained. The blocked polyisocyanate contained in the encapsulated blocked polyisocyanate can exhibit more properties as a curing agent.

The average functional group number of the polyisocyanate (preferably water-dispersible polyisocyanate) is preferably 2.5 or more and 4.5 or less, more preferably 2.8 or more and 4.0 or less, and 3.0. It is more preferable that it is more than or equal to 3.5 or less. When the average number of functional groups is at least the above lower limit, the strength of the resulting polyurea film can be more sufficiently maintained. The blocked polyisocyanate contained in the polyisocyanate can exhibit more properties as a curing agent.

The average number of functional groups is the number of isocyanate functional groups statistically possessed by one polyisocyanate molecule, and is calculated using the following formula from the number average molecular weight (Mn) of polyisocyanate and the isocyanate group content (NCO%). be able to.

(Average functional group number) = Mn x NCO%/4200

[Polyurethane film]
Polyurethane films are derived from polyols and polyisocyanates, ie, the reaction products of polyols and polyisocyanates.
As the polyisocyanate, the polyisocyanate described in the above "polyurea film" or the water-dispersible polyisocyanate can be used.

(polyol)
A polyol has two or more hydroxyl groups in one molecule that can react with an isocyanate group.
Examples of polyols include polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, fluorine polyols, polycarbonate polyols, and polyurethane polyols. These polyols may be contained singly or in combination of two or more.
Among these polyols, polyester polyols and acrylic polyols are preferable.

1. Polyester Polyol Polyester polyol can be obtained, for example, by condensing 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.

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, glycerin, and pentaerythritol. , 2-methylolpropanediol, ethoxylated trimethylolpropane, and the like.

Alternatively, for example, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone using a polyhydric alcohol can also be used as polyester polyols.

2. Polyether Polyol Polyether polyols are not particularly limited, and examples thereof include those shown in (1) to (3) below.
(1) Polyether polyols obtained by random or block addition of an alkylene oxide, alone or in mixture, to a polyhydric hydroxy compound, alone or in mixture, using a catalyst.
Examples of the catalyst include hydroxides (lithium, sodium, potassium, etc.), strongly basic catalysts (alcoholates, alkylamines, etc.), composite metal cyanide complexes (metal porphyrin, zinc hexacyanocobaltate complex, etc.), and the like. be done.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide.
(2) Polyether polyols obtained by reacting a polyamine compound with an alkylene oxide.
Examples of the polyamine compound include ethylenediamines.
Examples of the alkylene oxide include those exemplified in (1).
(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 polyvalent hydroxy compound include those shown in (i) to (vi) below.
(i) diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol and the like;
(ii) Sugar alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol and rhamnitol.
(iii) monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose and ribodesource;
(iv) Disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose and melibiose.
(v) trisaccharides such as raffinose, gentianose and melezitose;
(vi) tetrasaccharides such as stachyose;

3. Acrylic polyol The acrylic polyol is not particularly limited, but for example, an ethylenically unsaturated bond-containing monomer having a hydroxyl group or a mixture thereof, and other ethylenically unsaturated bond-containing monomers copolymerizable therewith alone or in a mixture, and those obtained by copolymerizing.

Examples of the ethylenically unsaturated bond-containing monomer having a hydroxy group include, but are not limited to, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and methacryl. and hydroxybutyl acid. These may be used alone or in combination of two or more. Among them, hydroxyethyl acrylate or hydroxyethyl methacrylate is preferable.

Other ethylenically unsaturated bond-containing monomers copolymerizable with the above monomers include, for example, the following (1) to (6). These may be used alone or in combination of two or more.
(1) Methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, acrylic acid acrylic acid esters such as lauryl, benzyl acrylate and phenyl acrylate;
(2) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid methacrylic acid esters such as lauryl, benzyl methacrylate and phenyl methacrylate;
(3) unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid;
(4) Unsaturated amides such as acrylamide, methacrylamide, N,N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, maleic acid amide and maleimide.
(5) Vinyl monomers such as glycidyl methacrylate, styrene, vinyl toluene, vinyl acetate, acrylonitrile, and dibutyl fumarate.
(6) Vinyl monomers having a hydrolyzable silyl group such as vinyltrimethoxysilane, vinylmethyldimethoxysilane and γ-(meth)acryloxypropyltrimethoxysilane.

4. Polyolefin Polyol The polyolefin polyol is not particularly limited, and examples thereof include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

The number of hydroxyl groups statistically possessed by one molecule of the polyol (hereinafter sometimes referred to as "average number of hydroxyl groups") is preferably 2 or more. When the average number of hydroxyl groups of the polyol is 2 or more, it tends to be possible to further suppress the decrease in the crosslink density of the coating film obtained by curing the one-component coating composition of the present embodiment.

5. Fluoropolyol As used herein, the term “fluoropolyol” means a polyol containing fluorine in its molecule. Specific examples of fluoropolyols include fluoroolefins, cyclovinyl ethers, hydroxy Examples thereof include copolymers of alkyl vinyl ethers, monocarboxylic acid vinyl esters, and the like.

6. Polycarbonate Polyol Polycarbonate polyols are not particularly limited, but include, for example, those shown in (1) to (4) below.
(1) dialkyl carbonate such as dimethyl carbonate;
(2) alkylene carbonates such as ethylene carbonate;
(3) diaryl carbonates such as diphenyl carbonate;
(4) Those obtained by polycondensation of low-molecular-weight carbonate compounds such as the above (1) to (3).

7. Polyurethane Polyol The polyurethane polyol is not particularly limited, but can be obtained, for example, by reacting a polyol containing no carboxy group with an isocyanate component by a conventional method.
Examples of polyols containing no carboxyl group include ethylene glycol, propylene glycol, and the like as low-molecular-weight polyols. Moreover, acrylic polyols, polyester polyols, polyether polyols, and the like are exemplified as high-molecular-weight polyols.

(Hydroxyl value of polyol)
Although the hydroxyl value of the polyol per resin is not particularly limited, it is preferably 10 mgKOH/g of resin or more and 300 mgKOH/g of resin or less.
When the hydroxyl value per resin is equal to or higher than the above lower limit, it tends to be possible to suppress the decrease in the crosslink density and more sufficiently achieve the desired physical properties. When the hydroxyl value per resin is equal to or less than the above upper limit, excessive increase in crosslink density is suppressed, and the mechanical properties of the coating film obtained by curing the one-component coating composition described later are further improved. tend to be able to
The hydroxyl value of polyol can be measured according to JIS K1557.

[Acrylic copolymer film]
Acrylic copolymer films are obtained by polymerizing acrylic monomers at the interface of oil droplets in water or in a low-polar solvent.
As the acrylic monomer, those described in "3. Acrylic polyol" in the "polyol" of the above "polyurethane film" are used.
As a specific production method, the method described in JP-A-2020-509930 (reference document 3) is exemplified.

<Blocked polyisocyanate>
Blocked polyisocyanates are derived from polyisocyanates and blocking agents. That is, a blocked polyisocyanate is a reaction product of a polyisocyanate and a blocking agent, and at least a portion (preferably all) of the isocyanate groups of the polyisocyanate are blocked by the blocking agent.

The polyisocyanate used as a raw material for the blocked polyisocyanate and the method for producing the same include those exemplified in the above "polyurea film".
The average number of functional groups of the polyisocyanate, which is the raw material of the blocked polyisocyanate, is not particularly limited, but is preferably 2.5 or more and 20.0 or less, preferably 2.8 or more and 10.0 or less. It is more preferably 0 or more and 8.0 or less, and most preferably 3.5 or more and 6.0 or less. When the average number of functional groups is at least the above lower limit, the resulting encapsulated block polyisocyanate can exhibit low-temperature curability. Storage stability can be expressed.

[Blocking agent]
Although the blocking agent is not particularly limited, for example, (1) alcohol compounds, (2) alkylphenol compounds, (3) phenol compounds, (4) active methylene compounds, (5) mercaptan compounds, (6) acid amide compound, (7) acid imide compound, (8) imidazole compound, (9) urea compound, (10) oxime compound, (11) amine compound, (12) imide compound, (13) ) bisulfite, (14) pyrazole compound, (15) pyridine compound, (16) guanidine compound, (17) imidazoline compound, (18) pyrimidine compound, (19) triazole compound, (20) Examples include tetrazole compounds. Specific examples of the blocking agent include those shown below.

(1) alcohol compounds: alcohols such as methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol and 2-butoxyethanol .
(2) Alkylphenol-based compounds: mono- and dialkylphenols having an alkyl group having 4 or more carbon atoms as a substituent. 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;
(3) Phenolic compounds: phenol, cresol, ethylphenol, styrenated phenol, hydroxybenzoic acid ester and the like.
(4) Active methylene compounds: dimethyl malonate, diethyl malonate, diisopropyl malonate, di-tert-butyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone.
(5) Mercaptan compounds: butyl mercaptan, dodecyl mercaptan and the like.
(6) acid amide compounds: acetanilide, acetic amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam and the like.
(7) acid imide compounds: succinimide, maleic imide and the like;
(8) Imidazole compounds: imidazole, 2-methylimidazole, 2-ethylimidazole, 4-methylimidazole, benzimidazole 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.
(14) Pyrazole compounds: pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like.
(15) Pyridine compounds: 2-(methylamino)pyridine, 4-hydroxypyridine, 2-hydroxypyridine and the like.
(16) Guanidine compounds: 3,3-dimethylguanidine, 1,1,3,3-tetramethylguanidine and the like.
(17) Imidazoline compounds: 2-methylimidazoline, 2-phenylimidazoline and the like.
(18) Pyrimidine compounds: 2-methyl-1,4,5,6-tetrahydropyrimidine and the like.
(19) Triazole compounds: 1,2,4-triazole, 1,2,3-triazole, 3,5-dimethyl-1,2,4-triazole and the like.
(20) Tetrazole compounds: 1H-1,2,3,4-tetrazole and the like.

Among them, the blocking agent preferably contains at least one compound selected from the group consisting of oxime-based compounds, amine-based compounds, triazole-based compounds, pyrazole-based compounds, imidazole-based compounds, and active methylene-based compounds. More preferably, a triazole-based compound, a pyrazole-based compound, or an imidazole-based compound is included, and more preferably an imidazole-based compound is included.

Among the triazole compounds, 1,2,4-triazole, 1,2,3-triazole and 3,5-dimethyl-1,2,4-triazole are preferred.

Among pyrazole compounds, 3,5-dimethylpyrazole is preferred.

Among imidazole compounds, 2-methylimidazole or 2-ethylimidazole is preferred.

[Method for producing blocked polyisocyanate]
When the blocked polyisocyanate is a blocked polyisocyanate derived from a polyisocyanate and a blocking agent, the blocked polyisocyanate can be obtained, for example, by reacting the polyisocyanate with the blocking agent.

The blocking reaction between the polyisocyanate and the blocking agent can be carried out with or without the presence of a solvent to give a blocked polyisocyanate.

From the viewpoint of the storage stability of the one-component coating composition, the mixing ratio of the polyisocyanate and the blocking agent is the molar ratio of the active hydrogen groups contained in the blocking agent when the isocyanate group contained in the polyisocyanate is set to 1. is preferably 0.5 or more and 3.0 or less, more preferably 0.8 or more and 2.0 or less, and further preferably 1 or more and 1.5 or less.

In the reaction step, the reaction temperature and reaction time are appropriately determined according to the progress of the reaction. The reaction temperature is preferably 0° C. or higher and 150° C. or lower, and the reaction time is preferably 0.5 hours or longer and 24 hours or shorter.

When two types of blocking agents are used in combination, the blocking reaction with two types of blocking agents may be carried out simultaneously, and free isocyanate groups remaining after first blocking with one blocking agent are blocked with the other blocking agent. You may

Moreover, in the reaction, if necessary, a known normal catalyst may be used. The catalyst is not particularly limited, but includes, for example, the following (1) to (6). You may use the catalyst shown below individually or in mixture.
(1) Tin octoate, tin 2-ethyl-1-hexanoate, tin ethylcaproate, tin laurate, tin palmitate, dibutyltin oxide, dibutyltin dichloride, dibutyltin diacetate, dibutyltin dimalate, dibutyltin dilaurate, dioctyltindi Organotin compounds such as acetate and dioctyltin dilaurate;
(2) organic zinc compounds such as zinc chloride, zinc octanoate, zinc 2-ethyl-1-hexanoate, zinc 2-ethylcaproate, zinc stearate, zinc naphthenate, zinc acetylacetonate;
(3) organotitanium compounds;
(4) organic zirconium compounds;
(5) tertiary amines such as triethylamine, tributylamine, N,N-diisopropylethylamine, N,N-dimethylethanolamine;
(6) diamines such as triethylenediamine, tetramethylethylenediamine, 1,4-diazabicyclo[2.2.2]octane;

The completion of the reaction can be determined, for example, by confirming the disappearance or reduction of isocyanate groups using infrared spectroscopy or the like.

Moreover, when using a solvent, a solvent inert to an isocyanate group may be used.
When a solvent is used, the content of solids derived from the polyisocyanate and the blocking agent relative to 100 parts by mass of the blocked polyisocyanate component 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. parts by mass or less, and more preferably 30 parts by mass or more and 70 parts by mass or less.

Alternatively, when the blocked polyisocyanate is a blocked polyisocyanate derived from a polyisocyanate, a hydrophilic compound and a blocking agent, it can be obtained, for example, by reacting the polyisocyanate, the hydrophilic compound and the blocking agent.

The reaction between the isocyanate groups of 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 one of the reactions can be carried out in advance and then the second reaction can be carried out. can also Among them, the isocyanate group and a hydrophilic compound are first reacted to obtain a polyisocyanate modified with a hydrophilic compound (hereinafter sometimes referred to as "modified polyisocyanate"), and then the obtained modified polyisocyanate and a blocking agent.

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 100° 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, the blocked isocyanate composition of the present embodiment tends to more effectively suppress deterioration in water dispersion stability and low-temperature curability when used as a coating composition.

The blocking reaction between a polyisocyanate or modified polyisocyanate and a blocking agent can be carried out with or without the presence of a solvent to give a blocked polyisocyanate.

The blocking reaction can be carried out by the reaction exemplified in the manufacturing method when the above-mentioned blocked polyisocyanate is a blocked polyisocyanate derived from a polyisocyanate and a blocking agent.

When using water or a solvent, a solvent inert to isocyanate groups may be used.
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, 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, 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.

When a solvent is used, the content of solids derived from the polyisocyanate and the blocking agent relative to 100 parts by mass of the blocked polyisocyanate component 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. parts by mass or less, and more preferably 30 parts by mass or more and 70 parts by mass or less.

When water is used, it is preferable to divide a predetermined amount or add it dropwise. In the case of division, it is preferable to divide the predetermined amount into 4 or more and 8 or less. In addition, when the blocked polyisocyanate concentration in water is 55% by mass or more, the liquid temperature is kept at 50°C or higher, at 45% by mass or higher and lower than 55% by weight, at 45°C or higher and 50°C or lower, and at lower than 45% by weight, the liquid temperature is lower than 50°C. preferable.
When water is added all at once or when the liquid temperature is 80°C or higher and lower than 20°C, the average particle size (average dispersed particle size) of the aqueous dispersion of the blocked polyisocyanate increases, causing precipitation and separation. The stability of the aqueous dispersion may decrease, such as occurrence of Therefore, the blocked polyisocyanate concentration of the aqueous dispersion composition thus obtained is preferably 10% by mass or more and 40% by mass or less.

<Method for producing encapsulated block polyisocyanate>
The method for producing the encapsulated block polyisocyanate of this embodiment will be described in detail below.
The capsule component (also referred to as shell layer) of the encapsulated block polyisocyanate comprises one or more crosslinked coating films selected from the group consisting of polyurea films, polyurethane films and acrylic copolymer films.

[Method for forming polyurea film]
A polyurea film is formed by the reaction of a polyamine compound and a polyisocyanate.

In addition, in the reaction between the polyamine compound and the polyisocyanate, the molar ratio of the amine group (amine group/isocyanate group) derived from the polyamine compound to the isocyanate group of the polyisocyanate is not particularly limited, but the molar ratio of the amine group/isocyanate group is 0. It is preferably 0.2 or more and 5 or less, more preferably 0.33 or more and 4 or less, further preferably 0.5 or more and 2.5 or less, and 0.6 or more and 1.5. Especially preferred. When the molar ratio of amine group/isocyanate group is at least the above lower limit, the polyurea film can be formed more sufficiently, while at the above upper limit or less, the blocked polyisocyanate forming the core layer. better separation after encapsulation of

Although the method for forming the polyurea film is not particularly limited, it is preferable to use an interfacial polymerization method.
Specifically, as a method for producing the encapsulated block polyisocyanate of the present embodiment, a method including the following steps is preferably exemplified.
A step of mixing a blocked polyisocyanate that forms the core layer and a water-dispersible polyisocyanate that is a raw material of the shell layer to prepare a mixture (hereinafter sometimes referred to as “step 1”):
A step of dispersing the mixture in water to prepare a dispersed aqueous solution (hereinafter sometimes referred to as “step 2”);
A step of dropping a polyamine compound into the dispersion aqueous solution to form a polyurea film derived from the water-dispersible polyisocyanate and the polyamine compound by an interfacial polymerization method, and coating the blocked polyisocyanate with the polyurea film. (Hereinafter, it may be called "process 3").

In step 1, a block polyisocyanate and a water-dispersible polyisocyanate are uniformly mixed to prepare a mixture.
At this time, if necessary, a solvent is added. The type of solvent and the amount of the solvent to be added can be appropriately selected so that the above components are uniformly dispersed in the mixture. Among them, a hydrophobic solvent is preferable as the solvent. Hydrophobic solvents include, for example, toluene, xylene, and butyl acetate.

In step 2, the mixture is dispersed in water to prepare a dispersion solution in which the organic components containing the blocked polyisocyanate and the water-dispersible polyisocyanate are dispersed in water. A method for preparing the dispersion solution is not particularly limited, but an example thereof includes a method of stirring the mixture while dropping it into water. The dropping speed is not particularly limited, and can be appropriately adjusted so that the oil droplets composed of the organic component have a desired size. The temperature is not particularly limited, either, and for example, it can be carried out at room temperature (about 5° C. or higher and 35° C. or lower). After the dropwise addition is completed, a dispersion solution in which the organic component is uniformly dispersed can be obtained by stirring for 1 minute or more and 30 minutes or less.

In step 3, the dispersion solution is stirred while the polyamine compound is added dropwise. As a result, the polyamine compound added to the reaction system is dispersed in water, approaches and reacts with the oil droplets containing the water-dispersible polyisocyanate, and forms a polyurea film at the interface between the oil droplets and water.

Although the temperature at which the polyamine compound is added is not particularly limited, it is preferably 0° C. or higher and 80° C. or lower, more preferably 20° C. or higher and 40° C. or lower. When the temperature is equal to or higher than the above lower limit, the formation rate of the polyurea film can be more sufficiently maintained, while when the temperature is equal to or lower than the above upper limit, local reactions are suppressed and finer capsules are formed. can do.

Further, the reaction time after the addition of the polyamine compound is preferably 30 minutes or more and 360 minutes or less, more preferably 60 minutes or more and 240 minutes or less.

[Method for Forming Polyurethane Film]
Polyurethane films are formed by the reaction of polyols and polyisocyanates.

In addition, in the reaction between the polyol and the polyisocyanate, the molar ratio of the hydroxyl groups derived from the polyol to the isocyanate groups of the polyisocyanate (hydroxyl groups/isocyanate groups) is not particularly limited. is preferably 0.33 or more and 4 or less, more preferably 0.5 or more and 2.5 or less, and particularly preferably 0.6 or more and 1.5. When the hydroxyl group/isocyanate group molar ratio is at least the above lower limit, a polyurethane film can be formed more satisfactorily. Better isolation after encapsulation.

A method for forming the polyurethane film is not particularly limited, but it is preferable to use an interfacial polymerization method.
Specifically, as a method for producing the encapsulated block polyisocyanate of the present embodiment, a method including the following steps is preferably exemplified.
A step of mixing a blocked polyisocyanate that forms the core layer and a water-dispersible polyisocyanate that is a raw material of the shell layer to prepare a mixture (hereinafter sometimes referred to as “step 1”):
A step of dispersing the mixture in water to prepare a dispersed aqueous solution (hereinafter sometimes referred to as “step 2”);
A step of dropping a polyol into the dispersion aqueous solution to form a polyurethane film derived from the water-dispersible polyisocyanate and the polyol by an interfacial polymerization method, and coating the blocked polyisocyanate with the polyurethane film (hereinafter referred to as , may be referred to as “Step 3”).

In step 1, a block polyisocyanate and a water-dispersible polyisocyanate are uniformly mixed to prepare a mixture.
At this time, if necessary, a solvent is added. The type of solvent and the amount of the solvent to be added can be appropriately selected so that the above components are uniformly dispersed in the mixture. Among them, a hydrophobic solvent is preferable as the solvent. Hydrophobic solvents include, for example, toluene, xylene, and butyl acetate.

In step 2, the mixture is dispersed in water to prepare a dispersion solution in which the organic components containing the blocked polyisocyanate and the water-dispersible polyisocyanate are dispersed in water. A method for preparing the dispersion solution is not particularly limited, but an example thereof includes a method of stirring the mixture while dropping it into water. The dropping speed is not particularly limited, and can be appropriately adjusted so that the oil droplets composed of the organic component have a desired size. The temperature is not particularly limited, either, and for example, it can be carried out at room temperature (about 5° C. or higher and 35° C. or lower). After the dropwise addition is completed, a dispersion solution in which the organic component is uniformly dispersed can be obtained by stirring for 1 minute or more and 30 minutes or less.

In step 3, the dispersion solution is stirred while the polyol is added dropwise. As a result, the polyol added to the reaction system is dispersed in water, approaches and reacts with the oil droplets containing the water-dispersible polyisocyanate, and forms a polyurethane film at the interface between the oil droplets and water.

Although the temperature at which the polyol is added is not particularly limited, it is preferably 0° C. or higher and 80° C. or lower, more preferably 20° C. or higher and 40° C. or lower. When the temperature is equal to or higher than the above lower limit, the formation rate of the polyurethane film can be more sufficiently maintained. can do.

The reaction time after the addition of the polyol is preferably 2 hours or more and 24 hours or less, more preferably 4 hours or more and 20 hours or less, and even more preferably 6 hours or more and 15 hours or less.

[Method for Forming Acrylic Copolymer Film]
Although the method for forming the acrylic copolymer film is not particularly limited, it is preferable to use an interfacial polymerization method.
Specifically, as a method for producing the encapsulated block polyisocyanate of the present embodiment, a method including the following steps is preferably exemplified.
A step of mixing a blocked polyisocyanate that forms the core layer and a plurality of acrylic monomers that are raw materials of the shell layer to prepare a mixture (hereinafter sometimes referred to as “step 1”):
A step of dispersing the mixture in water to prepare a dispersed aqueous solution (hereinafter sometimes referred to as “step 2”);
A polymerization initiator is added dropwise to the dispersed aqueous solution, and an acrylic copolymer film derived from the acrylic monomer is formed at the interface between the blocked polyisocyanate and water by an interfacial polymerization method, thereby converting the blocked polyisocyanate into the A step of coating with an acrylic copolymer film (hereinafter sometimes referred to as “step 3”).

In step 1, an acrylic monomer and a blocked polyisocyanate are uniformly mixed to prepare a mixture.
At this time, if necessary, a solvent is added. The type of solvent and the amount of the solvent to be added can be appropriately selected so that the above components are uniformly dispersed in the mixture. Among them, a hydrophobic solvent is preferable as the solvent. Hydrophobic solvents include, for example, toluene, xylene, and butyl acetate.

In step 2, the mixture is dispersed in water to prepare a dispersion solution in which the acrylic monomer and the organic component containing the blocked polyisocyanate are dispersed in water. A method for preparing the dispersion solution is not particularly limited, but an example thereof includes a method of stirring the mixture while dropping it into water. The dropping speed is not particularly limited, and can be appropriately adjusted so that the oil droplets composed of the organic component have a desired size. The temperature is not particularly limited, either, and for example, it can be carried out at room temperature (about 5° C. or higher and 35° C. or lower). After the dropwise addition is completed, a dispersion solution in which the organic component is uniformly dispersed can be obtained by stirring for 1 minute or more and 30 minutes or less.

In step 3, the dispersion solution is stirred while the polymerization initiator is added dropwise. As a result, the polymerization initiator added to the reaction system is dispersed in water, approaches the oil droplets, and forms an acrylic copolymer film at the interface between the oil droplets and water where the blocked polyisocyanate is present.

The temperature at which the polymerization initiator is added is not particularly limited, but is preferably 0° C. or higher and 100° C. or lower, more preferably 30° C. or higher and 80° C. or lower, and 40° C. or higher and 60° C. or lower. More preferred. When the temperature is at least the above lower limit, the rate of formation of the acrylic copolymer film can be more sufficiently maintained, while at the above upper limit or less, local reactions are suppressed and finer capsules are formed. can be formed.

Further, the reaction time after addition of the polymerization initiator is preferably 1 hour or more and 24 hours or less, more preferably 2 hours or more and 15 hours or less, and further preferably 3 hours or more and 10 hours or less. .

<Physical properties of encapsulated block polyisocyanate>
The median diameter of the encapsulated blocked polyisocyanate of the present embodiment is preferably 10 nm or more and 5 μm or less, more preferably 30 nm or more and 4 μm or less, and even more preferably 50 nm or more and 2 μm or less. When the median diameter is equal to or greater than the above lower limit, the aggregation stability can be further maintained, while when the median diameter is equal to or less than the above upper limit, sedimentation in the coating liquid can be suppressed.
The median diameter referred to here is the 50% diameter ( _d50 ).

In the encapsulated blocked polyisocyanate of the present embodiment, the content of the blocked polyisocyanate, which is an active ingredient, is, for example, 1% by mass or more and 80% by mass or less with respect to the total mass of the solid content of the encapsulated blocked polyisocyanate. 5% by mass or more and 70% by mass or less, 10% by mass or more and 65% by mass or less, or 20% by mass or more and 60% by mass or less.

<<Dispersion of encapsulated block polyisocyanate>>
The above-described encapsulated block polyisocyanate can be used in a state of being dispersed in water or an organic solvent such as toluene, xylene or butyl acetate. In particular, by using it in a state of being dispersed in water, a water-based one-component coating composition, which will be described later, can be obtained. That is, in one embodiment, the present invention provides an aqueous dispersion of encapsulated blocked polyisocyanate, which is obtained by dispersing the above-described encapsulated blocked polyisocyanate in water.
In addition, by using it in a state of being dispersed in an organic solvent, a solvent-based one-liquid coating composition to be described later can be obtained.

The content of the encapsulated block polyisocyanate in the dispersion may be, for example, 1% by mass or more and 80% by mass or less, and may be 5% by mass or more and 75% by mass or less, relative to the total mass of the dispersion. can be 10% by mass or more and 70% by mass or less, and can be 20% by mass or more and 60% by mass or less.

<Other ingredients>
The dispersion of encapsulated block polyisocyanate may further contain one or more selected from the group consisting of other curing agents, antioxidants, light stabilizers, polymerization inhibitors and surfactants. Among them, it is preferable to further contain a surfactant.

Other curing agents include, for example, melamine resins, urea resins, epoxy group-containing compounds or resins, carboxy group-containing compounds or resins, acid anhydrides, alkoxysilane group-containing compounds or resins, hydrazide compounds, and the like.

Antioxidants and light stabilizers include, for example, aliphatic, aromatic or alkyl-substituted aromatic esters of phosphoric acid or phosphorous acid, hypophosphorous acid derivatives; phenylphosphonic acid, phenylphosphinic acid, diphenylphosphonic acid, polyphosphonates, Phosphorus compounds such as dialkylpentaerythritol diphosphite and dialkylbisphenol A diphosphite; Sulfur-containing compounds such as propionate; and tin-based compounds such as tin malate and dibutyltin monoxide. These may be contained singly or in combination of two or more.

Examples of polymerization inhibitors include hydroquinones, phenols, cresols, catechols, and benzoquinones. Specific examples of polymerization inhibitors include benzoquinone, p-benzoquinone, p-toluquinone, p-xyloquinone, naphthoquinone, 2,6-dichloroquinone, hydroquinone, trimethylhydroquinone, catechol, p-tert-butylcatechol, 2, 5-di-tert-butyl hydroquinone, monomethyl hydroquinone, p-methoxyphenol, 2,6-di-tert-butyl-p-cresol, hydroquinone monomethyl ether and the like. These may be contained singly or in combination of two or more.

Examples of surfactants include known anionic surfactants, cationic surfactants, and amphoteric surfactants.

≪Coating composition≫
Hereinafter, solvent-based one-component coating compositions and water-based one-component coating compositions may be collectively referred to as coating compositions.

<Content of encapsulated block polyisocyanate>
The coating composition of this embodiment contains the above-described encapsulated block polyisocyanate. Since the coating composition of the present embodiment contains the above-described encapsulated block polyisocyanate, a coating film having excellent storage stability, low-temperature curability, and scratch resistance can be obtained.
The content of the encapsulated blocked polyisocyanate in the coating composition of the present embodiment is not particularly limited. A/B is preferably 0.1 or more and 10 or less, more preferably 0.2 or more and 5 or less, and 0.3 or more and 3 or less. is more preferably 0.4 or more and 2 or less.
When the content of the encapsulated block polyisocyanate is at least the above lower limit, the low-temperature curability and scratch resistance of the coating film can be improved. On the other hand, when it is equal to or less than the above upper limit, the low-temperature curability can be further improved.

<One-component coating composition>
The solvent-based one-component coating composition of the present embodiment contains the above-described encapsulated blocked polyisocyanate (preferably an organic solvent dispersion of encapsulated blocked polyisocyanate) and a polyvalent active hydrogen compound.

Further, the water-based one-liquid coating composition of the present embodiment contains the water dispersion of the above-described encapsulated block polyisocyanate and a polyvalent active hydrogen compound.

Each constituent component of the one-liquid type coating composition of the present embodiment will be described in detail below.

[Polyvalent active hydrogen compound]
Examples of polyvalent active hydrogen compounds include, but are not limited to, polyols, polyamines, alkanolamines, and the like. These polyvalent active hydrogen compounds may be contained singly or in combination of two or more. Among them, the polyvalent active hydrogen compound is preferably a polyol.

(polyol)
Examples include polyester polyols, polyether polyols, acrylic polyols, polyolefin polyols, fluorine polyols, polycarbonate polyols, and polyurethane polyols. These polyols may be contained singly or in combination of two or more.
Among these polyols, polyester polyols and acrylic polyols are preferable.

1. Polyester Polyol The polyester polyol can be obtained, for example, by condensation reaction of 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.

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, glycerin, and pentaerythritol. , 2-methylolpropanediol, ethoxylated trimethylolpropane, and the like.

Alternatively, for example, polycaprolactones obtained by ring-opening polymerization of lactones such as ε-caprolactone using a polyhydric alcohol can also be used as polyester polyols.

2. Polyether Polyol Polyether polyols are not particularly limited, and examples thereof include those shown in (1) to (3) below.
(1) Polyether polyols obtained by random or block addition of an alkylene oxide, alone or in mixture, to a polyhydric hydroxy compound, alone or in mixture, using a catalyst.
Examples of the catalyst include hydroxides (lithium, sodium, potassium, etc.), strongly basic catalysts (alcoholates, alkylamines, etc.), composite metal cyanide complexes (metal porphyrin, zinc hexacyanocobaltate complex, etc.), and the like. be done.
Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, cyclohexene oxide, and styrene oxide.
(2) Polyether polyols obtained by reacting a polyamine compound with an alkylene oxide.
Examples of the polyamine compound include ethylenediamines.
Examples of the alkylene oxide include those exemplified in (1).
(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 polyvalent hydroxy compound include those shown in (i) to (vi) below.
(i) diglycerin, ditrimethylolpropane, pentaerythritol, dipentaerythritol and the like;
(ii) Sugar alcohol compounds such as erythritol, D-threitol, L-arabinitol, ribitol, xylitol, sorbitol, mannitol, galactitol and rhamnitol.
(iii) monosaccharides such as arabinose, ribose, xylose, glucose, mannose, galactose, fructose, sorbose, rhamnose, fucose and ribodesource;
(iv) Disaccharides such as trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose and melibiose.
(v) trisaccharides such as raffinose, gentianose and melezitose;
(vi) tetrasaccharides such as stachyose;

3. Acrylic polyol The acrylic polyol is not particularly limited, but for example, an ethylenically unsaturated bond-containing monomer having a hydroxyl group or a mixture thereof, and other ethylenically unsaturated bond-containing monomers copolymerizable therewith alone or in a mixture, and those obtained by copolymerizing.

Examples of the ethylenically unsaturated bond-containing monomer having a hydroxy group include, but are not limited to, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, and methacryl. and hydroxybutyl acid. These may be used alone or in combination of two or more. Among them, hydroxyethyl acrylate or hydroxyethyl methacrylate is preferable.

Other ethylenically unsaturated bond-containing monomers copolymerizable with the above monomers include, for example, the following (1) to (6). These may be used alone or in combination of two or more.
(1) Methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, acrylic acid acrylic acid esters such as lauryl, benzyl acrylate and phenyl acrylate;
(2) Methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid methacrylic acid esters such as lauryl, benzyl methacrylate and phenyl methacrylate;
(3) unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid;
(4) Unsaturated amides such as acrylamide, methacrylamide, N,N-methylenebisacrylamide, diacetone acrylamide, diacetone methacrylamide, maleic acid amide and maleimide.
(5) Vinyl monomers such as glycidyl methacrylate, styrene, vinyl toluene, vinyl acetate, acrylonitrile, and dibutyl fumarate.
(6) Vinyl monomers having a hydrolyzable silyl group such as vinyltrimethoxysilane, vinylmethyldimethoxysilane and γ-(meth)acryloxypropyltrimethoxysilane.

4. Polyolefin Polyol The polyolefin polyol is not particularly limited, and examples thereof include polybutadiene having two or more hydroxyl groups, hydrogenated polybutadiene, polyisoprene, and hydrogenated polyisoprene.

The number of hydroxyl groups statistically possessed by one molecule of the polyol (hereinafter sometimes referred to as "average number of hydroxyl groups") is preferably 2 or more. When the average number of hydroxyl groups of the polyol is 2 or more, the decrease in the crosslink density of the coating film obtained by curing the one-component coating composition of the present embodiment tends to be more suppressed.

5. Fluoropolyol As used herein, the term “fluoropolyol” means a polyol containing fluorine in its molecule. Specific examples of fluoropolyols include fluoroolefins, cyclovinyl ethers, hydroxy Examples thereof include copolymers of alkyl vinyl ethers, monocarboxylic acid vinyl esters, and the like.

6. Polycarbonate Polyol Polycarbonate polyols are not particularly limited, but include, for example, those shown in (1) to (4) below.
(1) dialkyl carbonate such as dimethyl carbonate;
(2) alkylene carbonates such as ethylene carbonate;
(3) diaryl carbonates such as diphenyl carbonate;
(4) Those obtained by polycondensation of low-molecular-weight carbonate compounds such as the above (1) to (3).

7. Polyurethane Polyol The polyurethane polyol is not particularly limited, but can be obtained, for example, by reacting a polyol containing no carboxy group with an isocyanate component by a conventional method.
Examples of polyols containing no carboxyl group include ethylene glycol, propylene glycol, and the like as low-molecular-weight polyols. Moreover, acrylic polyols, polyester polyols, polyether polyols, and the like are exemplified as high-molecular-weight polyols.

(Hydroxyl value of polyol)
Although the hydroxyl value of the polyol per resin is not particularly limited, it is preferably 10 mgKOH/g of resin or more and 300 mgKOH/g of resin or less.
When the hydroxyl value per resin is equal to or higher than the above lower limit, it tends to be possible to suppress the decrease in the crosslink density and more sufficiently achieve the intended physical properties. When the hydroxyl value per resin is equal to or less than the above upper limit, excessive increase in the crosslink density is suppressed, and the mechanical properties of the coating film obtained by curing the one-component coating composition of the present embodiment are improved. It tends to be improved.
The hydroxyl value of polyol can be measured according to JIS K1557.

(polyamine)
Polyamines are not particularly limited, but those having two or more primary amino groups or secondary amino groups per molecule are preferred, and those having three or more primary amino groups or secondary amino groups per molecule are more preferred. preferable.
Specific examples of polyamines include those shown in (1) to (3) below.
(1) Diamines such as ethylenediamine, propylenediamine, butylenediamine, triethylenediamine, hexamethylenediamine, 4,4'-diaminodicyclohexylmethane, piperazine, 2-methylpiperazine, and isophoronediamine;
(2) Chain polyamines having three or more amino groups, such as bishexamethylenetriamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentamethylenehexamine, and tetrapropylenepentamine;
(3) 1,4,7,10,13,16-hexaazacyclooctadecane, 1,4,7,10-tetraazacyclodecane, 1,4,8,12-tetraazacyclopentadecane, 1,4, cyclic polyamines such as 8,11-tetraazacyclotetradecane;

(Alkanolamine)
As used herein, "alkanolamine" means a compound having an amino group and a hydroxyl group in one molecule.
Specific examples of alkanolamine include monoethanolamine, diethanolamine, aminoethylethanolamine, N-(2-hydroxypropyl)ethylenediamine, mono-, di-(n- or iso-)propanolamine, ethylene glycol-bis - propylamine, neopentanolamine, methylethanolamine, and the like.

[Other urethanization catalysts]
The one-component coating composition of the present embodiment can further comprise other urethanization catalysts within a range that does not adversely affect storage stability.

The urethanization catalyst may be a basic compound or a Lewis acidic compound.

Examples of basic compounds include metal hydroxides, metal alkoxides, metal acetylacetinates, hydroxides of onium salts, halides of onium salts, metal salts of active methylene compounds, onium salts of active methylene compounds, aminosilanes, Amines, phosphines and the like can be mentioned. As onium salts, ammonium salts, phosphonium salts or sulfonium salts are suitable.

Examples of the Lewis acidic compound include organic tin compounds, organic zinc compounds, organic titanium compounds, organic zirconium compounds, and the like.

[Other resin components]
The one-component coating composition of the present embodiment can further comprise other resin components such as existing melamine resins, epoxy resins, polyurethane resins, etc., if necessary.

[Other additives]
When the one-component coating composition of the present embodiment comprises a polyol having a carboxyl group, it may further comprise other curing agents such as oxazoline group-containing compounds and carbodiimide group-containing compounds as curing agent components. These compounds may be contained individually by 1 type, and may be contained in combination of 2 or more types.

When the one-component coating composition of the present embodiment comprises a polyol having a carbonyl group, it can further comprise other curing agents such as hydrazide group-containing compounds and semicarbazide group-containing compounds as curing agent components. These compounds may be contained individually by 1 type, and may be contained in combination of 2 or more types.

The one-component coating composition of the present embodiment may optionally contain antioxidants, ultraviolet absorbers (light stabilizers), pigments, metal powder pigments, rheology control agents, curing accelerators, surfactants, solvents, etc. may further comprise other additives.
Antioxidants, light stabilizers, surfactants, and solvents are the same as those exemplified in the above-mentioned "encapsulated block polyisocyanate".
Examples of pigments include titanium oxide, carbon black, indigo, quinacridone, and pearl mica.
Examples of metal powder pigments include aluminum.
Rheology control agents include, for example, hydroxyethyl cellulose, urea compounds, microgels and the like.
Examples of curing accelerators include organometallic compounds other than the above urethanization catalysts. Metal species constituting the organometallic compound include, for example, tin, zinc, and lead.

<Method for producing coating composition>
To prepare the solvent-based one-liquid coating composition of the present embodiment, first, a polyvalent active hydrogen compound or its solvent-diluted product is added with other resin components and other additives, if necessary. Next, the encapsulated block polyisocyanate or its organic solvent dispersion is added as a curing agent component, and if necessary, a solvent is further added to adjust the viscosity. Then, the mixture is stirred by hand or by using a stirring device such as a masher to obtain a solvent-based one-component coating composition.

In the water-based one-liquid coating composition of the present embodiment, first, a polyvalent active hydrogen compound or its aqueous dispersion or aqueous solution is added with other resin components, other additives, and the like, if necessary. Next, an aqueous dispersion of the encapsulated block polyisocyanate is added as a curing agent component, and if necessary, water or a solvent is further added to adjust the viscosity. Then, by forcibly stirring with a stirring device, a water-based one-component coating composition can be obtained.

<Application>
The coating composition of the present embodiment can be applied to metals such as steel plates and surface-treated steel plates, plastics, inorganic materials, etc. by roll coating, curtain flow coating, spray coating, electrostatic coating, bell coating, immersion, roller coating, brush coating, etc. It is suitable for use as a primer, intermediate coat or top coat on ceramics, glass and concrete.
The coating composition of the present embodiment imparts cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, adhesion, etc. to pre-coated metals containing rust-proof steel plates, automobile painted parts, plastic painted parts, etc. It is preferably used for
The coating composition of this embodiment is also useful as an adhesive, adhesive, elastomer, foam, surface treatment agent, and the like.

≪Paint film≫
The coating film of this embodiment is obtained by curing the coating composition described above. The coating film of this embodiment is excellent in low-temperature curability and scratch resistance. The coating film of the present embodiment is obtained by coating the coating composition described above using a known method such as roll coating, curtain flow coating, spray coating, bell coating, and electrostatic coating, followed by normal temperature drying or baking, Obtained by curing.
The coating film obtained by curing the coating composition has urethane bonds. Therefore, the coating film of the present embodiment formed from the above coating composition tends to be excellent in chemical resistance, heat resistance, water resistance, etc., which are characteristics of general urethane crosslinked coating films.

≪Painted goods≫
The coated article of this embodiment comprises the coating film described above. The coated article of the present embodiment is excellent in low-temperature curability and scratch resistance by being provided with the coating film described above.

The coated article of the present embodiment is provided with the above coating film that is excellent in chemical resistance, heat resistance, water resistance, etc., and is further imparted with cosmetic properties, acid resistance, rust resistance, chipping resistance, adhesion, etc. ing.

EXAMPLES The present embodiment will be described in more detail below with reference to Examples, but the present embodiment is not limited to these Examples.

Methods for measuring various physical properties and evaluating various properties are described below. "Parts" and "%" mean "mass parts" and "mass%" unless otherwise specified.

[Physical properties 1]
(Isocyanate group (NCO) content of polyisocyanate)
About 1 g to 3 g of polyisocyanate was precisely weighed (Wg) in an Erlenmeyer flask. Then, 20 mL of toluene was added to dissolve the polyisocyanate. Next, 10 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. Then, the same operation was performed without polyisocyanate, and the obtained titration value was defined as V1 ml. Then, the isocyanate group (NCO) content of the polyisocyanate was calculated from the following formula.

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

[Physical properties 2]
(Solids content of (encapsulated) blocked polyisocyanate)
The solid content of the (encapsulated) blocked polyisocyanate was determined as follows.
First, an aluminum dish with a bottom diameter of 38 mm was precisely weighed. Next, while about 1 g was placed on an aluminum dish, the (encapsulated) block polyisocyanates produced in Synthesis Examples, Examples and Comparative Examples were accurately weighed (W1). The (encapsulated) blocked polyisocyanate was then adjusted to a uniform thickness. Then, the (encapsulated) blocked polyisocyanate placed on an aluminum dish was held in an oven at 105° C. for 1 hour. After the aluminum dish reached room temperature, the (encapsulated) blocked polyisocyanate remaining in the aluminum dish was accurately weighed (W2). Next, the solid content of the (encapsulated) block polyisocyanate was calculated from the following formula.

Solid content of (encapsulated) blocked polyisocyanate [% by mass]
= W2/W1 x 100

[Physical properties 3]
(Effective isocyanate group (NCO) content of blocked polyisocyanate)
The effective isocyanate group (NCO) content of the blocked polyisocyanate was determined as follows.
The term "effective isocyanate group (NCO) content" as used herein refers to the quantification of the amount of blocked isocyanate groups present in the blocked polyisocyanate component after the blocking reaction and capable of participating in the cross-linking reaction. It is expressed in mass % of isocyanate groups.
The effective NCO content was calculated by the following formula. In the following formula, "NCO %" and "solid content of blocked polyisocyanate" are the values calculated in the physical properties 1 and 2 above, respectively. In addition, when the sample was diluted with a solvent or the like, the value in the diluted state was calculated.

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

[Physical properties 4]
(Effective isocyanate group (NCO) content of encapsulated block polyisocyanate)
The effective isocyanate group (NCO) content of the encapsulated blocked polyisocyanate was calculated by the following formula, where Z is the effective isocyanate group (NCO) content of the above-described blocked polyisocyanate.
Effective NCO content [mass%]
= [Z x (mass of blocked polyisocyanate)]/(mass of encapsulated polyisocyanate after encapsulation reaction)

[Physical properties 5]
(Median diameter _D50 of encapsulated block polyisocyanate)
An aqueous dispersion of encapsulated block polyisocyanate obtained by diluting the obtained encapsulated block polyisocyanate median diameter D ₅₀ with deionized water to a concentration of 1% by mass was used as a sample, and UPA-EX150 (manufactured by Microtrac Bell Co., Ltd. ) was used.

[Evaluation 1]
(Low-temperature curability of one-liquid coating composition)
Each one-liquid type coating composition produced in Examples and Comparative Examples was applied to a polypropylene (PP) plate with an air spray gun so that the dry film thickness was 30 μm. It was then dried at 23°C for 15 minutes. Then, it was baked at a predetermined temperature for 30 minutes to obtain a cured coating film. The resulting cured coating film was left at 23° C. for 1 hour and peeled off from the PP plate. Then, after accurately weighing the mass (hereinafter referred to as "mass before immersion"), the sample was immersed in acetone at 20°C for 24 hours. Next, the mass after immersion (hereinafter referred to as "undissolved mass") was accurately weighed. Next, the ratio of the undissolved mass to the mass before immersion (gel fraction) was calculated. Then, the calculated gel fraction was evaluated for low-temperature curability based on the following evaluation criteria.

(Evaluation criteria)
◎: 80% by mass or more gel fraction at 90°C ○: 80% by mass or more gel fraction at 105°C △: 80% by mass or more gel fraction at 120°C ×: Less than 80% by mass gel fraction at 120°C

[Evaluation 2]
(Storage stability of one-component coating composition)
The appearance of each one-liquid coating composition after storage at 40° C. for 10 days was evaluated for storage stability based on the following evaluation criteria.

(Evaluation criteria)
○: When no significant change is observed △: Uniform but thickening is observed, or when clear separation is observed ×: Gelation

[Evaluation 3]
(Scratch resistance)
Each one-liquid type coating composition produced in Examples and Comparative Examples was applied to a polypropylene (PP) plate with an air spray gun so that the dry film thickness was 30 μm. It was then dried at 23°C for 15 minutes. Then, it was baked at 120° C. for 30 minutes to obtain a cured coating film. First, the initial gloss (G0) was measured for each coating film obtained. Then, on the painted surface (where the initial gloss (G0) was measured), using a 4-line brass brush manufactured by Industry Kowa, parallel to the handle, weight: 600 g, stroke speed: 30 cm / Seconds, stroke width: 20 reciprocations of 5 cm to make a scratch.
Next, the sample used in the scratch resistance evaluation was left in a constant temperature room at 23° C. for 24 hours. After 24 hours, the gloss (G1) of the scratched area was measured. Then, the gloss retention rate was calculated using the following formula, and the scratch resistance was evaluated according to the following evaluation criteria.

Gloss retention rate [%] = (G1/G0) x 100

(Evaluation criteria)
○: Gloss retention rate of 90% or more △: Gloss retention rate of 80% or more and less than 90% ×: Gloss retention rate of less than 80%

<Synthesis of polyisocyanate>
[Synthesis Example 1-1]
(Synthesis of polyisocyanate P-1)
A four-necked flask equipped with a thermometer, stirring blades and a reflux condenser was charged with 1000 parts by mass of HDI and 2 parts by mass of 2-ethylhexane-1,3-diol under a nitrogen stream and stirred. The temperature inside the reactor was kept at 70° C. while the temperature was low. Tetramethylammonium hydroxide was added thereto, and when the NCO content of the reaction liquid at 25° C. reached 38.7% by mass, phosphoric acid was added to stop the reaction. After filtering the reaction solution, unreacted HDI was removed by a thin film distillation apparatus to obtain polyisocyanate P-1 having an NCO content of 21.8% by mass. The number average molecular weight was 670 and the average number of isocyanate groups was 3.5.

[Synthesis Example 1-2]
(Synthesis of polyisocyanate P-2)
In a four-necked flask equipped with a thermometer, a stirring blade and a reflux condenser, HDI: 1000 parts by mass and a polyester polyol derived from a trihydric alcohol and ε-caprolactone (manufactured by Daicel Chemical Industries, Ltd.) are added under a nitrogen stream. , "PLAXEL 303" (trade name), average number of hydroxyl functional groups: 3, number average molecular weight: 300): 52 parts by mass were charged, and the temperature inside the reactor was kept at 88°C for 1 hour under stirring to carry out a urethanization reaction. Thereafter, the temperature inside the reactor was maintained at 62° C., and an isocyanurate-forming catalyst, tetramethylammonium capriate, was added, and when the NCO content of the reaction liquid reached 34.1 mass %, phosphoric acid was added to terminate the reaction. After filtering the reaction solution, unreacted HDI was removed by a thin film distillation apparatus to obtain polyisocyanate P-2 having an NCO content of 18.8% by mass. The number average molecular weight was 1180 and the average number of isocyanate groups was 5.3.

[Synthesis Example 1-3]
(Synthesis of water-dispersible polyisocyanate P-3)
In a four-necked flask equipped with a thermometer, stirring blades and a reflux condenser, under a nitrogen stream, polyisocyanate P-1 obtained in Synthesis Example 1-1: 100 parts by mass, the average number of ethylene oxide repeating units 9.0 polyethylene glycol monomethyl ether (manufactured by Nippon Nyukazai Co., Ltd., trade name "MPG-130"): 15.5 parts by mass was added, and the reaction was carried out by stirring at 100°C for 4 hours under nitrogen. After completion of the reaction, a water-dispersible polyisocyanate P-3 having an NCO content of 17.5% by mass was obtained.

[Synthesis Example 1-4]
(Synthesis of water-dispersible polyisocyanate P-4)
In a four-necked flask equipped with a thermometer, stirring blades and a reflux condenser, isophorone diisocyanate-based polyisocyanurate (manufactured by Evonik, trade name "T1890/100"): 100 parts by mass, dipropylene glycol Dimethyl ether (manufactured by Dow Chemical Company, trade name “DMM”): 64 parts by mass, and polyethylene glycol monomethyl ether having an average number of ethylene oxide repeating units of 9.0 (manufactured by Nippon Nyukazai Co., Ltd., trade name “MPG-130”) : 12.3 parts by mass were added, and the reaction was carried out by stirring at 100°C for 4 hours under nitrogen. After completion of the reaction, a water-dispersible polyisocyanate P-4 having an NCO content of 9.1% by mass was obtained.

<Synthesis of block polyisocyanate component>
[Synthesis Example 2-1]
(Production of blocked polyisocyanate component BL-1)
A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen blowing tube was set to a nitrogen atmosphere, and the polyisocyanate P-1 obtained in Synthesis Example 1-1: 100 parts by mass, and toluene: 97.7 parts by mass. 4 parts by mass was added, then 3,5-dimethylpyrazole: 52.3 parts by mass was gradually added, and the mixture was stirred for 3 hours at a temperature of 50°C or less for a blocking reaction to obtain an effective NCO%. A blocked polyisocyanate component BL-1 having a solid content of 8.7 mass % and a solid content of 60 mass % was obtained.

[Synthesis Example 2-2]
(Production of blocked polyisocyanate component BL-2)
A stirrer, a thermometer, a reflux condenser, a four-necked flask equipped with a nitrogen blowing tube was set to a nitrogen atmosphere, and the polyisocyanate P-1 obtained in Synthesis Example 1-1: 100 parts by mass and toluene 97.4 2-Ethylimidazole: 52.3 parts by mass was gradually added, and the mixture was stirred for 3 hours under temperature conditions of 50°C or less for blocking reaction, and the effective NCO% was 8.7 mass. , to obtain a blocked polyisocyanate component BL-2 having a solid content of 60% by mass.

[Synthesis Example 2-3]
(Production of blocked polyisocyanate component BL-3)
A stirrer, a thermometer, a reflux condenser, and a four-necked flask equipped with a nitrogen blowing tube are set to a nitrogen atmosphere, and the polyisocyanate P-2 obtained in Synthesis Example 1-2: 100 parts by mass and toluene 93.1 2-ethylimidazole: 45.1 parts by mass was gradually added, and the mixture was stirred for 3 hours under a temperature condition of 50°C or less for blocking reaction, and the effective NCO% was 7.9 mass. , to obtain a blocked polyisocyanate component BL-3 having a solid content of 60% by mass.

[Synthesis Example 2-4]
(Production of blocked polyisocyanate component BL-4)
A stirrer, a thermometer, a reflux condenser, and a four-necked flask equipped with a nitrogen blowing tube were set to a nitrogen atmosphere, and the polyisocyanate P-2 obtained in Synthesis Example 1-2: 100 parts by mass and toluene 90.7 30.0 parts by mass of 2-ethylimidazole and 10.9 parts of 1.2.4-triazole are gradually added, and the mixture is stirred for 3 hours under a temperature condition of 50°C or less to form a block. A reaction was carried out to obtain a blocked polyisocyanate component BL-4 having an effective NCO % of 7.9 mass % and a solid content of 60 mass %.

[Synthesis Example 2-5]
(Production of blocked polyisocyanate component BL-5)
A four-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen blowing tube was set to a nitrogen atmosphere, and the polyisocyanate P-1 obtained in Synthesis Example 1-1: 100 parts by mass, toluene 109.1 parts by mass , and methoxypolyethylene glycol (MPG-081, ethylene oxide repeating unit: 15, manufactured by Nippon Nyukazai Co., Ltd.): 22.2 parts by mass were added, and the mixture was maintained at 120° C. for 2 hours while being heated and stirred. After that, the mixture is cooled to 40°C with stirring, and 47.1 parts by mass of 2-ethylimidazole is gradually added, and the mixture is stirred for 3 hours at a temperature of 50°C or less for blocking reaction to obtain effective NCO%. A blocked polyisocyanate component BL-5 having a weight of 7.0% and a solid content of 60% by weight was obtained.

<Production of encapsulated block polyisocyanate>
[Example 1-1]
(Production of encapsulated block polyisocyanate C-1, encapsulated block polyisocyanate butyl acetate dispersion C-1-50SB, encapsulated block polyisocyanate aqueous dispersion C-1-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-1: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-3: 29.7 parts by mass are stirred to prepare a pre-mixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. Then, polyaspartic acid ester compound (manufactured by Covestro, trade name "Desmophen 1420", amine value 201 mg KOH/resin g) (hereinafter sometimes abbreviated as "D1420"): 34.3 parts by mass over 10 minutes After completion of the dropping, the solution was stirred for 4 hours to obtain an aqueous solution of encapsulated block polyisocyanate C-1 (solid content: 23.6% by mass). The median diameter of the obtained C-1 was 200 nm.

Thereafter, ion-exchanged water is further added to the resulting encapsulated blocked polyisocyanate C-1 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and the capsule components. rice field. Thereafter, the aqueous layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass), followed by stirring for 10 minutes to obtain an encapsulated block polyisocyanate butyl acetate dispersion. C-1-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-1-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-2]
(Production of encapsulated block polyisocyanate C-2, encapsulated block polyisocyanate butyl acetate dispersion C-2-50SB, encapsulated block polyisocyanate aqueous dispersion C-2-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-2: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-4: 57.1 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. Then, D1420: 34.3 parts by mass was added dropwise over 10 minutes, and after the dropwise addition was completed, the solution was stirred for 4 hours to obtain an aqueous encapsulated block polyisocyanate C-2 solution (solid content: 23.7% by mass). . The median diameter of the obtained C-2 was 110 nm.

Thereafter, ion-exchanged water is further added to the resulting encapsulated blocked polyisocyanate C-2 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and capsule components. rice field. Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-2-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-2-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-3]
(Production of encapsulated block polyisocyanate C-3, encapsulated block polyisocyanate butyl acetate dispersion C-3-50SB, encapsulated block polyisocyanate aqueous dispersion C-3-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-2: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-4: 57.1 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. After that, polyester polyol (manufactured by Daicel Corporation, trade name “PLAXEL 305”, hydroxyl value 305 mg KOH/g of resin) (hereinafter sometimes abbreviated as “PL305”): 23.9 parts by mass was added dropwise over 10 minutes. After completion of dropping, the mixture was stirred for 10 hours to obtain an aqueous solution of encapsulated block polyisocyanate C-3 (solid content: 22.3% by mass). The median diameter of the obtained C-3 was 120 nm.

After that, ion-exchanged water is further added to the resulting encapsulated block polyisocyanate C-3 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and the capsule component. rice field. Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-3-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-3-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-4]
(Production of encapsulated block polyisocyanate C-4, encapsulated block polyisocyanate butyl acetate dispersion C-4-50SB, encapsulated block polyisocyanate aqueous dispersion C-4-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-3: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-3: 29.7 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. Then, D1420: 34.3 parts by mass was added dropwise over 10 minutes, and after the dropwise addition was completed, the mixture was stirred for 4 hours to obtain an aqueous solution of encapsulated block polyisocyanate C-4 (solid content: 23.6% by mass). . The median diameter of the obtained C-4 was 180 nm.

Thereafter, ion-exchanged water is further added to the resulting encapsulated blocked polyisocyanate C-4 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and capsule components. rice field. Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-4-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-4-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-5]
(Production of Encapsulated Blocked Polyisocyanate C-5, Encapsulated Blocked Polyisocyanate Butyl Acetate Dispersion C-5-50SB, and Encapsulated Blocked Polyisocyanate Aqueous Dispersion C-5-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-3: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-4: 57.1 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. Thereafter, D1420: 34.3 parts by mass was added dropwise over 10 minutes, and after the dropwise addition was completed, the solution was stirred for 4 hours to obtain an aqueous encapsulated block polyisocyanate C-5 solution (solid content: 23.7% by mass). . The median diameter of the obtained C-5 was 80 nm.

Thereafter, ion-exchanged water was further added to the resulting encapsulated blocked polyisocyanate C-4 aqueous solution C-5, diluted to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to remove the water layer and capsule components. separated into Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-5-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-5-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-6]
(Production of encapsulated block polyisocyanate C-6, encapsulated block polyisocyanate butyl acetate dispersion C-6-50SB, encapsulated block polyisocyanate aqueous dispersion C-6-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-3: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-4: 57.1 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. After that, PL305: 23.9 parts by mass was added dropwise over 10 minutes, and after the dropwise addition was completed, the solution was stirred for 10 hours to obtain an aqueous encapsulated block polyisocyanate C-6 solution (solid content: 22.3% by mass). . The median diameter of the obtained C-6 was 90 nm.

Thereafter, ion-exchanged water is further added to the resulting encapsulated blocked polyisocyanate C-6 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and the capsule component. rice field. Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-6-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-6-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-7]
(Production of Encapsulated Blocked Polyisocyanate C-7, Encapsulated Blocked Polyisocyanate Butyl Acetate Dispersion C-7-50SB, and Encapsulated Blocked Polyisocyanate Aqueous Dispersion C-7-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-4: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-4: 57.1 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. Then, D1420: 34.3 parts by mass was added dropwise over 10 minutes, and after the dropwise addition was completed, the solution was stirred for 4 hours to obtain an aqueous solution of encapsulated block polyisocyanate C-7 (solid content: 23.7% by mass). . The median diameter of the obtained C-7 was 80 nm.

After that, ion-exchanged water is further added to the resulting encapsulated block polyisocyanate C-7 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and the capsule component. rice field. Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-7-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-7-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-8]
(Production of Encapsulated Blocked Polyisocyanate C-8, Encapsulated Blocked Polyisocyanate Butyl Acetate Dispersion C-8-50SB, and Encapsulated Blocked Polyisocyanate Aqueous Dispersion C-8-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-2: 100 parts by mass, toluene: 60 parts by mass, and polyisocyanate P-4: 57.1 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water. Thereafter, 2,2'-diaminodiethylamine: 4.2 parts by mass was added dropwise over 10 minutes, and after the dropwise addition was completed, the solution was stirred for 4 hours, and an aqueous solution of encapsulated block polyisocyanate C-8 (solid content: 19.3) was added. mass %) was obtained. The median diameter of the obtained C-8 was 300 nm.

Thereafter, ion-exchanged water is further added to the resulting encapsulated blocked polyisocyanate C-8 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and capsule components. rice field. Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-8-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-8-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

[Example 1-9]
(Production of encapsulated block polyisocyanate C-9, encapsulated block polyisocyanate butyl acetate dispersion C-9-50SB, encapsulated block polyisocyanate aqueous dispersion C-9-50W)
In a four-necked flask equipped with a stirrer, a thermometer, and a reflux condenser, ion-exchanged water: 300 parts by mass, and an anionic surfactant (manufactured by Nippon Nyukazai Co., Ltd., product name "Newcol N2320-SN") (hereinafter , sometimes abbreviated as “N2320-SN”): 2.5 parts by mass were added and stirred to prepare a reaction system. Next, block polyisocyanate component BL-1: 100 parts by mass, toluene: 20 parts by mass, and polyisocyanate P-3: 29.7 parts by mass are stirred to prepare a premixed organic mixture, and then react. The mixture was added dropwise to the system over 30 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes to disperse the organic liquid mixture in water.
After that, 1,4-butanediol diacrylate: 3 parts by mass, methyl methacrylate: 17 parts by mass, and methacrylic anhydride: 13 parts by mass are stirred and mixed in advance to prepare an organic mixed liquid, and then in the reaction system. was added dropwise over 10 minutes, and after the dropwise addition was completed, the mixture was stirred for 10 minutes. Next, 0.7 parts by mass of a 75% by mass toluene solution of tert-butyl perpivalate was added over 60 minutes, followed by stirring at 50° C. for 4 hours. Next, a 10% by mass aqueous solution of tert-butyl hydroperoxide was added, followed by stirring at 20° C. for 60 minutes to obtain an aqueous encapsulated block polyisocyanate C-9 solution (solid content: 20.4% by mass). The median diameter of the obtained C-9 was 3800 nm.

After that, ion-exchanged water is further added to the resulting encapsulated block polyisocyanate C-9 aqueous solution to dilute it to a solid content of 10% by mass, and centrifuged at 50,000 rpm for 30 minutes to separate the water layer and the capsule component. rice field. Thereafter, the water layer was removed, and 8 parts by mass of butyl acetate was added to 10 parts by mass of the resulting capsule component (solid content: 90% by mass) and stirred for 10 minutes to disperse the encapsulated block polyisocyanate in butyl acetate. Body C-9-50SB (solid content: 50% by mass) was obtained.
Further, to the obtained capsule component (solid content: 90 parts by mass): 10 parts by mass, distilled water: 8 parts by mass was added and stirred for 10 minutes to obtain a water dispersion C-9-50W of encapsulated block polyisocyanate. (Solid content: 50% by mass) was obtained.

<Production of solvent-based one-part coating composition>
[Example 2-1]
(Production of solvent-based one-component coating composition Sa2-1)
Acrylic polyol (manufactured by Allnex, "Setalux 1767" (trade name), hydroxyl group concentration 4.5% by mass (based on resin), solid content concentration 65% by mass): 10.0 parts by mass, butyl acetate: 11.4 parts by mass was added, and then 50% by mass of encapsulated block polyisocyanate butyl acetate solution: C-1-50SB: 20.6 parts by mass was added and stirred for 5 minutes to prepare a solvent-based one-liquid coating composition Sa2-1. Obtained.

[Examples 2-2 to 2-4 and Comparative Example 2-1]
(Production of solvent-based one-component coating compositions Sa2-2 to Sa2-4 and Sb2-1)
Each solvent-based one-component coating composition was produced in the same manner as in Example 2-1, except that the compositions and blending amounts shown in Table 5 were used.

Table 5 below shows the results of evaluation by the evaluation method described above using each solvent-based one-liquid coating composition.

From Table 5, the solvent-based one-component coating compositions Sa2-1 to Sa2-4 (Examples 2-1 to 2-4) containing encapsulated block polyisocyanate have storage stability, and when formed into a coating film, Both low-temperature curability and scratch resistance were good.
Sa2-2 to Sa2-4 (Examples 2-2 to 2-4) using 2-ethylimidazole as a blocking agent for the encapsulated blocked polyisocyanate are Sa2 whose blocking agent is 3,5-dimethylpyrazole. -1 (Example 2-1) tended to be more excellent in low-temperature curability.
In addition, Sa2-1 to Sa2-3 (Examples 2-1 to 2-3) in which the shell layer is a polyurea film have higher scratch resistance than Sa2-4 (Example 2-4), which is a polyurethane film. A trend toward improvement was observed.

On the other hand, in the solvent-based one-part coating composition Sb2-1 (Comparative Example 2-1) to which an unencapsulated blocked polyisocyanate was added, the low-temperature curability when made into a coating film was better, but storage Poor stability.

<Production of water-based one-component coating composition>
[Example 3-1]
(Production of water-based one-component coating composition Wa3-1)
Ion-exchanged water: 3.4 parts by mass, surfactant (manufactured by Nippon Nyukazai Co., Ltd., "New Call 2320SN" (trade name)) (hereinafter sometimes referred to as "N2320-SN"): 0.5 parts by mass was added and stirred with a squirrel motor. 10.0 parts by mass of acrylic dispersion (manufactured by Allnex, "SETAQUA6515" (trade name), hydroxyl group concentration 3.3% by mass (based on resin), solid content concentration 45% by mass) was added thereto while stirring. Then, 10.4 parts by mass of encapsulated block polyisocyanate C-1-50W was added over 10 minutes and stirred for 10 minutes to obtain a water-based one-liquid coating composition Wa3-1.

[Examples 3-2 to 3-9 and Comparative Example 3-1]
(Production of water-based one-component coating compositions Wa3-2 to Wa3-9 and Wb3-1)
Each water-based one-liquid coating composition was produced in the same manner as in Example 3-1, except that the compositions and blending amounts shown in Tables 6 and 7 were used.

Tables 6 and 7 below show the results of evaluation by the evaluation method described above using each water-based one-liquid coating composition.

From Tables 6 and 7, the water-based one-component coating compositions Wa3-1 to Wa3-9 (Examples 3-1 to 3-9) containing encapsulated block polyisocyanate have storage stability and Both the low-temperature curability and the scratch resistance were good.
Wa3-2 to Wa3-8 (Examples 3-2 to 3-8) using 2-ethylimidazole as the blocking agent for the encapsulation block polyisocyanate are Wa3 in which the blocking agent is 3,5-dimethylpyrazole. -1 (Example 3-1) and Wa3-9 (Example 3-9) tended to be more excellent in low-temperature curability.
Furthermore, among them, Wa3-4 to Wa3-6 (Examples 3-4 to 3-6) using a polyisocyanate having a higher average number of functional groups as the polyisocyanate of the encapsulating block polyisocyanate have low-temperature curability. A particularly good tendency was observed.
In addition, Wa3-2 to Wa3-3 (Examples 3-2 to 3-3) and Wa3-5 to Wa3-7 (Examples 3-5 to 3-3) in which the median diameter of the encapsulated block polyisocyanate is 150 nm or less -7) is more storage stable than Wa3-1 (Example 3-1), Wa3-4 (Example 3-4), and Wa3-8 to 3-9 (Examples 3-8 to 3-9) tended to be better.
In addition, Wa3-1 to Wa3-2 (Examples 3-1 to 3-2), Wa3-4 to Wa3-5 (Examples 3-4 to 3-5), and Wa3- where the shell layer is a polyurea film 7 to 3-8 (Examples 3-7 to 3-8) are polyurethane films Wa3-3 (Example 3-3) and Wa3-6 (Example 3-6), and an acrylic copolymer film Wa3-9 (Example 3-9) tended to be more excellent in scratch resistance.

On the other hand, in the water-based one-liquid coating composition Wb3-1 (Comparative Example 3-1) to which unencapsulated blocked polyisocyanate BL-5 was added, the low-temperature curability was good, but the storage stability and scratch resistance were good. was of poor quality.

According to the encapsulated block polyisocyanate of the present embodiment, a coating composition having excellent storage stability can be obtained, and a coating film having excellent low-temperature curability and scratch resistance can be obtained. The coating composition of the present embodiment contains the encapsulated block polyisocyanate, and provides a coating film that is excellent in storage stability, low-temperature curability, and scratch resistance. The coating composition of the present embodiment is suitably used as a primer, an intermediate coat, or a top coat on materials such as metals, plastics and inorganic materials. The coating composition of the present embodiment provides cosmetic properties, weather resistance, acid resistance, rust resistance, chipping resistance, adhesion, etc. to pre-coated metals containing rust-proof steel plates, painted parts of automobiles, painted parts of plastics, etc. It is preferably used for imparting The coating composition of the present embodiment is also useful as a urethane raw material for adhesives, adhesives, elastomers, foams, surface treatment agents, and the like.

Claims (8)

An encapsulated block polyisocyanate comprising a block polyisocyanate coated with one or more crosslinked coating films selected from the group consisting of polyurea films, polyurethane films and acrylic copolymer films. 2. The encapsulated blocked polyisocyanate according to claim 1, wherein said crosslinked coating film is a polyurea film. An aqueous dispersion of an encapsulated blocked polyisocyanate, which is obtained by dispersing the encapsulated blocked polyisocyanate according to claim 1 or 2 in water. An encapsulated blocked polyisocyanate according to claim 1 or 2;
a polyvalent active hydrogen compound;
A solvent-based one-part coating composition containing an aqueous dispersion of the encapsulated blocked polyisocyanate according to claim 3;
a polyvalent active hydrogen compound;
A water-based one-liquid coating composition containing A coating film obtained by curing the solvent-based one-component coating composition according to claim 4. A coating film obtained by curing the water-based one-component coating composition according to claim 5 . A coated article comprising the coating film according to claim 6 or 7.